Zinc composite anode for batteries with solid electrolyte

Energy Technology Data Exchange (ETDEWEB)

Tedjar, F.; Melki, T.; Zerroual, L. (Setif Univ. (Algeria). Unite de Recherche Electrochimie)

1992-05-01

A new negative composite anode for batteries with a solid electrolyte is studied. Using a complex of zinc ammonium chloride mixed with zinc metal powder, the advantage of the Zn/Zn[sup 2+] electrode (e = -760 mV) is kept while the energy density and the shelf-life of the battery are increased. (orig.).

Friction stir processed Al - Metal oxide surface composites: Anodization and optical appearance

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Jensen, Flemming; Canulescu, Stela

2014-01-01

Multiple-pass friction stir processing (FSP) was employed to impregnate metal oxide (TiO2, Y2O3 and CeO2) particles into the surface of an Aluminium alloy. The surface composites were then anodized in a sulphuric acid electrolyte. The effect of anodizing parameters on the resulting optical...... dark to greyish white. This is attributed to the localized microstructural and morphological differences around the metal oxide particles incorporated into the anodic alumina matrix. The metal oxide particles in the FSP zone electrochemically shadowed the underlying Al matrix and modified the local...

Boron oxide–tin oxide/graphene composite as anode materials for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Wen, Lina [Department of chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Qin, Xue, E-mail: qinxue@tju.edu.cn [Department of chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071 (China); Meng, Wei; Cao, Ning; Song, Zhonghai [Department of chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China)

2016-11-15

Highlights: • B{sub 2}O{sub 3}–SnO{sub 2}/G anode material is prepared by chemical heat solvent method for LIBs. • B{sub 2}O{sub 3}–SnO{sub 2}/G shows much improved cycling performance and rate capability. • B{sub 2}O{sub 3} plays an important role in improving the performance. - Abstract: B{sub 2}O{sub 3}–SnO{sub 2}/graphene (B{sub 2}O{sub 3}–SnO{sub 2}/G) composite is fabricated via a chemical heat solvent method and utilized as anode material for lithium ion batteries. The added B{sub 2}O{sub 3} dramatically improves the electrochemical performance of lithium ion batteries compared to the SnO{sub 2}/G composite. The B{sub 2}O{sub 3}–SnO{sub 2}/G composites as anode show an outstanding discharge capacity of 1404.9 mAh g{sup −1} at 500 mA g{sup −1} after 200 cycles and an excellent rate capacity, which apparently outperforms the previously reported SnO{sub 2}-based anode material. These improved electrochemical performance characteristics are due to the B{sub 2}O{sub 3} played a buffering role, which are easily beneficial for accommodating the volume change during the lithium ions insertion/extraction processes. Furthermore, boron atoms can accept electrons for its electron-deficient nature and boron ions could release electrons, which lead to electrons' increased density and conductivity are increased. The results indicate that the B{sub 2}O{sub 3}–SnO{sub 2}/G composite is a promising anode material for lithium ion batteries.

Preparation and Anodizing of SiCp/Al Composites with Relatively High Fraction of SiCp.

Science.gov (United States)

Wang, Bin; Qu, Shengguan; Li, Xiaoqiang

2018-01-01

By properly proportioned SiC particles with different sizes and using squeeze infiltration process, SiCp/Al composites with high volume fraction of SiC content (Vp = 60.0%, 61.2%, 63.5%, 67.4%, and 68.0%) were achieved for optical application. The flexural strength of the prepared SiC p /Al composites was higher than 483 MPa and the elastic modulus was increased from 174.2 to 206.2 GPa. With an increase in SiC volume fraction, the flexural strength and Poisson's ratio decreased with the increase in elastic modulus. After the anodic oxidation treatment, an oxidation film with porous structure was prepared on the surface of the composite and the oxidation film was uniformly distributed. The anodic oxide growth rate of composite decreased with SiC content increased and linearly increased with anodizing time.

Preparation and Anodizing of SiCp/Al Composites with Relatively High Fraction of SiCp

Directory of Open Access Journals (Sweden)

Bin Wang

2018-01-01

Full Text Available By properly proportioned SiC particles with different sizes and using squeeze infiltration process, SiCp/Al composites with high volume fraction of SiC content (Vp = 60.0%, 61.2%, 63.5%, 67.4%, and 68.0% were achieved for optical application. The flexural strength of the prepared SiCp/Al composites was higher than 483 MPa and the elastic modulus was increased from 174.2 to 206.2 GPa. With an increase in SiC volume fraction, the flexural strength and Poisson’s ratio decreased with the increase in elastic modulus. After the anodic oxidation treatment, an oxidation film with porous structure was prepared on the surface of the composite and the oxidation film was uniformly distributed. The anodic oxide growth rate of composite decreased with SiC content increased and linearly increased with anodizing time.

Preparation and Anodizing of SiCp/Al Composites with Relatively High Fraction of SiCp

Science.gov (United States)

2018-01-01

By properly proportioned SiC particles with different sizes and using squeeze infiltration process, SiCp/Al composites with high volume fraction of SiC content (Vp = 60.0%, 61.2%, 63.5%, 67.4%, and 68.0%) were achieved for optical application. The flexural strength of the prepared SiCp/Al composites was higher than 483 MPa and the elastic modulus was increased from 174.2 to 206.2 GPa. With an increase in SiC volume fraction, the flexural strength and Poisson's ratio decreased with the increase in elastic modulus. After the anodic oxidation treatment, an oxidation film with porous structure was prepared on the surface of the composite and the oxidation film was uniformly distributed. The anodic oxide growth rate of composite decreased with SiC content increased and linearly increased with anodizing time. PMID:29682145

MnO-carbon hybrid nanofiber composites as superior anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Wang, Jian-Gan; Yang, Ying; Huang, Zheng-Hong; Kang, Feiyu

2015-01-01

MnO-carbon hybrid nanofiber composites are fabricated by electrospinning polyimide/manganese acetylacetonate precursor and a subsequent carbonization process. The composition, phase structure and morphology of the composites are characterized by scanning and transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. The results indicate that the composites exhibit good nanofibrous morphology with MnO nanoparticles uniformly encapsulated by carbon nanofibers. The hybrid nanofiber composites are used directly as freestanding anodes for lithium-ion batteries to evaluate their electrochemical properties. It is found that the optimized MnO-carbon nanofiber composite can deliver a high reversible capacity of 663 mAh g −1 , along with excellent cycling stability and good rate capability. The superior performance enables the composites to be promising candidates as an anode alternative for high-performance lithium-ion batteries

Microstructure and optical appearance of anodized friction stir processed Al - Metal oxide surface composites

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Jensen, Flemming; Bordo, Kirill

2014-01-01

Multiple-pass friction stir processing (FSP) was employed to impregnate Ti, Y and Ce oxide powders into the surface of an Aluminium alloy. The FSP processed surface composite was subsequently anodized with an aim to develop optical effects in the anodized layer owing to the presence of incorporated...... oxide particles which will influence the scattering of light. This paper presents the investigations on relation between microstructure of the FSP zone and optical appearance of the anodized layer due to incorporation of metal oxide particles and modification of the oxide particles due to the anodizing...

Anodization Mechanism on SiC Nanoparticle Reinforced Al Matrix Composites Produced by Power Metallurgy

OpenAIRE

Ferreira, Sonia C.; Conde, Ana; Arenas, Mar?a A.; Rocha, Luis A.; Velhinho, Alexandre

2014-01-01

Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050) anodi...

Hard carbon coated nano-Si/graphite composite as a high performance anode for Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Jeong, Sookyung; Li, Xiaolin; Zheng, Jianming; Yan, Pengfei; Cao, Ruiguo; Jung, Hee Joon; Wang, Chong M.; Liu, Jun; Zhang, Jiguang

2016-08-27

With the ever increasing demands on Li-ion batteries with higher energy densities, alternative anode with higher reversible capacity is required to replace the conventional graphite anode. Here, we demonstrate a cost-effective hydrothermal-carbonization approach to prepare the hard carbon coated nano-Si/graphite (HC-nSi/G) composite as a high performance anode for Li-ion batteries. In this hierarchical structured composite, the hard carbon coating layer not only provides an efficient pathway for electron transfer, but also alleviates the volume variation of silicon during charge/discharge processes. The HC-nSi/G composite electrode shows excellent electrochemical performances including a high specific capacity of 878.6 mAh g-1 based on the total weight of composite, good rate performance and a decent cycling stability, which is promising for practical applications.

Anode Fall Formation in a Hall Thruster

International Nuclear Information System (INIS)

Dorf, Leonid A.; Raitses, Yevgeny F.; Smirnov, Artem N.; Fisch, Nathaniel J.

2004-01-01

As was reported in our previous work, accurate, nondisturbing near-anode measurements of the plasma density, electron temperature, and plasma potential performed with biased and emissive probes allowed the first experimental identification of both electron-repelling (negative anode fall) and electron-attracting (positive anode fall) anode sheaths in Hall thrusters. An interesting new phenomenon revealed by the probe measurements is that the anode fall changes from positive to negative upon removal of the dielectric coating, which appears on the anode surface during the course of Hall thruster operation. As reported in the present work, energy dispersion spectroscopy analysis of the chemical composition of the anode dielectric coating indicates that the coating layer consists essentially of an oxide of the anode material (stainless steel). However, it is still unclear how oxygen gets into the thruster channel. Most importantly, possible mechanisms of anode fall formation in a Hall thruster with a clean and a coated anodes are analyzed in this work; practical implication of understanding the general structure of the electron-attracting anode sheath in the case of a coated anode is also discussed

A Combined Thermodynamics & Computational Method to Assess Lithium Composition in Anode and Cathode of Lithium Ion Batteries

International Nuclear Information System (INIS)

Zhang, Wenyu; Jiang, Lianlian; Van Durmen, Pauline; Saadat, Somaye; Yazami, Rachid

2016-01-01

With aim to address the open question of accurate determination of lithium composition in anode and cathode at a defined state of charge (SOC) of lithium ion batteries (LIB), we developed a method combining electrochemical thermodynamic measurements (ETM) and computational data fitting protocol. It is a common knowledge that in a lithium ion battery the SOC of anode and cathode differ from the SOC of the full-cell. Differences are in large part due to irreversible lithium losses within cell and to electrode mass unbalance. This implies that the lithium composition range in anode and in cathode during full charge and discharge cycle in full-cell is different from the composition range achieved in lithium half-cells of anode and cathode over their respective full SOC ranges. To the authors knowledge there is no unequivocal and practical method to determine the actual lithium composition of electrodes in a LIB, hence their SOC. Yet, accurate lithium composition assessment is fundamental not only for understanding the physics of electrodes but also for optimizing cell performances, particularly energy density and cycle life.

Carbon Cryogel Silicon Composite Anode Materials for Lithium Ion Batteries

Science.gov (United States)

Woodworth James; Baldwin, Richard; Bennett, William

2010-01-01

A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. 10 One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nano-foams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. 1-4,9 Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

Novel Lead dioxide-Graphite-Polymer composite anode for electrochemical chlorine generation

Czech Academy of Sciences Publication Activity Database

Gedam, N.; Neti, R.N.; Kormunda, M.; Šubrt, Jan; Bakardjieva, Snejana

2015-01-01

Roč. 169, JUL (2015), s. 109-116 ISSN 0013-4686 Institutional support: RVO:61388980 Keywords : beta-Lead dioxide * Graphite * Polymer composite anode * Chlorine generation * Cyclic voltammetry Subject RIV: CG - Electrochemistry Impact factor: 4.803, year: 2015

Experimental Studies of the Effects of Anode Composition and Process Parameters on Anode Slime Adhesion and Cathode Copper Purity by Performing Copper Electrorefining in a Pilot-Scale Cell

Science.gov (United States)

Zeng, Weizhi; Wang, Shijie; Free, Michael L.

2016-10-01

Copper electrorefining tests were conducted in a pilot-scale cell under commercial tankhouse environment to study the effects of anode compositions, current density, cathode blank width, and flow rate on anode slime behavior and cathode copper purity. Three different types of anodes (high, mid, and low impurity levels) were used in the tests and were analyzed under SEM/EDS. The harvested copper cathodes were weighed and analyzed for impurities concentrations using DC Arc. The adhered slimes and released slimes were collected, weighed, and analyzed for compositions using ICP. It was shown that the lead-to-arsenic ratio in the anodes affects the sintering and coalescence of slime particles. High current density condition can improve anode slime adhesion and cathode purity by intensifying slime particles' coalescence and dissolving part of the particles. Wide cathode blanks can raise the anodic current densities significantly and result in massive release of large slime particle aggregates, which are not likely to contaminate the cathode copper. Low flow rate can cause anode passivation and increase local temperatures in front of the anode, which leads to very intense sintering and coalescence of slime particles. The results and analyses of the tests present potential solutions for industrial copper electrorefining process.

Optical appearance of AC anodized Al/TiO2 composite coatings

DEFF Research Database (Denmark)

Bordo, Kirill; Gudla, Visweswara Chakravarthy; Ambat, Rajan

2014-01-01

amplitudes. The microstructure and composition of the obtained anodic films were determined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The optical appearance of the films was characterized by optical reflectance spectroscopy...

Graphene encapsulated Fe3O4 nanorods assembled into a mesoporous hybrid composite used as a high-performance lithium-ion battery anode material

DEFF Research Database (Denmark)

Huang, Wei; Xiao, Xinxin; Engelbrekt, Christian

2017-01-01

The discovery of new anode materials and engineering their fine structures are the core elements in the development of new-generation lithium ion batteries (LIBs). To this end, we herein report a novel nanostructured composite consisting of approximately 75% Fe3O4 nanorods and 25% reduced graphene...

Medium-chain-length poly-3-hydroxyalkanoates-carbon nanotubes composite anode enhances the performance of microbial fuel cell.

Science.gov (United States)

Hindatu, Y; Annuar, M S M; Subramaniam, R; Gumel, A M

2017-06-01

Insufficient power generation from a microbial fuel cell (MFC) hampers its progress towards utility-scale development. Electrode modification with biopolymeric materials could potentially address this issue. In this study, medium-chain-length poly-3-hydroxyalkanoates (PHA)/carbon nanotubes (C) composite (CPHA) was successfully applied to modify the surface of carbon cloth (CC) anode in MFC. Characterization of the functional groups on the anodic surface and its morphology was carried out. The CC-CPHA composite anode recorded maximum power density of 254 mW/m 2 , which was 15-53% higher than the MFC operated with CC-C (214 mW/m 2 ) and pristine CC (119 mW/m 2 ) as the anode in a double-chambered MFC operated with Escherichia coli as the biocatalyst. Electrochemical impedance spectroscopy and cyclic voltammetry showed that power enhancement was attributed to better electron transfer capability by the bacteria for the MFC setup with CC-CPHA anode.

Effects of the Formulations of Silicon-Based Composite Anodes on their Mechanical, Storage, and Electrochemical Properties.

Science.gov (United States)

Assresahegn, Birhanu Desalegn; Bélanger, Daniel

2017-10-23

In this work, the effects of the formulation of silicon-based composite anodes on their mechanical, storage, and electrochemical properties were investigated. The electrode formulation was changed through the use of hydrogenated or modified (through the covalent attachment of a binding additive such as polyacrylic acid) silicon and acetylene black or graphene sheets as conducting additives. A composite anode with a covalently grafted binder had the highest elongation without breakages and strong adhesion to the current collector. These mechanical properties depend significantly on the conductive carbon additive used and the use of graphene sheets instead of acetylene black can improve elongation and adhesion significantly. After 180 days of storage under ambient conditions, the electronic conductivity and discharge capacity of the modified silicon electrode showed much smaller decreases in these properties than those of the hydrogenated silicon composite electrode, indicating that the modification can result in passivation and a constant composition of the active material. Moreover, the composite Si anode has a high packing density. Consequently, thin-film electrodes with very high material loadings can be prepared without decreased electrochemical performance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

In-situ study of the gas-phase composition and temperature of an intermediate-temperature solid oxide fuel cell anode surface fed by reformate natural gas

Science.gov (United States)

Santoni, F.; Silva Mosqueda, D. M.; Pumiglia, D.; Viceconti, E.; Conti, B.; Boigues Muñoz, C.; Bosio, B.; Ulgiati, S.; McPhail, S. J.

2017-12-01

An innovative experimental setup is used for in-depth and in-operando characterization of solid oxide fuel cell anodic processes. This work focuses on the heterogeneous reactions taking place on a 121 cm2 anode-supported cell (ASC) running with a H2, CH4, CO2, CO and steam gas mixture as a fuel, using an operating temperature of 923 K. The results have been obtained by analyzing the gas composition and temperature profiles along the anode surface in different conditions: open circuit voltage (OCV) and under two different current densities, 165 mA cm-2 and 330 mA cm-2, corresponding to 27% and 54% of fuel utilization, respectively. The gas composition and temperature analysis results are consistent, allowing to monitor the evolution of the principal chemical and electrochemical reactions along the anode surface. A possible competition between CO2 and H2O in methane internal reforming is shown under OCV condition and low current density values, leading to two different types of methane reforming: Steam Reforming and Dry Reforming. Under a current load of 40 A, the dominance of exothermic reactions leads to a more marked increase of temperature in the portion of the cell close to the inlet revealing that current density is not uniform along the anode surface.

Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

Science.gov (United States)

Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

2018-06-05

Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

Embedded Si/Graphene Composite Fabricated by Magnesium-Thermal Reduction as Anode Material for Lithium-Ion Batteries

Science.gov (United States)

Zhu, Jiangliu; Ren, Yurong; Yang, Bo; Chen, Wenkai; Ding, Jianning

2017-12-01

Embedded Si/graphene composite was fabricated by a novel method, which was in situ generated SiO2 particles on graphene sheets followed by magnesium-thermal reduction. The tetraethyl orthosilicate (TEOS) and flake graphite was used as original materials. On the one hand, the unique structure of as-obtained composite accommodated the large volume change to some extent. Simultaneously, it enhanced electronic conductivity during Li-ion insertion/extraction. The MR-Si/G composite is used as the anode material for lithium ion batteries, which shows high reversible capacity and ascendant cycling stability reach to 950 mAh·g-1 at a current density of 50 mA·g-1 after 60 cycles. These may be conducive to the further advancement of Si-based composite anode design.

Facile synthesis and lithium storage properties of a porous NiSi2/Si/carbon composite anode material for lithium-ion batteries.

Science.gov (United States)

Jia, Haiping; Stock, Christoph; Kloepsch, Richard; He, Xin; Badillo, Juan Pablo; Fromm, Olga; Vortmann, Britta; Winter, Martin; Placke, Tobias

2015-01-28

In this work, a novel, porous structured NiSi2/Si composite material with a core-shell morphology was successfully prepared using a facile ball-milling method. Furthermore, the chemical vapor deposition (CVD) method is deployed to coat the NiSi2/Si phase with a thin carbon layer to further enhance the surface electronic conductivity and to mechanically stabilize the whole composite structure. The morphology and porosity of the composite material was evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption measurements (BJH analysis). The as-prepared composite material consists of NiSi2, silicon, and carbon phases, in which the NiSi2 phase is embedded in a silicon matrix having homogeneously distributed pores, while the surface of this composite is coated with a carbon layer. The electrochemical characterization shows that the porous and core-shell structure of the composite anode material can effectively absorb and buffer the immense volume changes of silicon during the lithiation/delithiation process. The obtained NiSi2/Si/carbon composite anode material displays an outstanding electrochemical performance, which gives a stable capacity of 1272 mAh g(-1) for 200 cycles at a charge/discharge rate of 1C and a good rate capability with a reversible capacity of 740 mAh g(-1) at a rate of 5C.

Lanthanum doped strontium titanate - ceria anodes: deconvolution of impedance spectra and relationship with composition and microstructure

Science.gov (United States)

Burnat, Dariusz; Nasdaurk, Gunnar; Holzer, Lorenz; Kopecki, Michal; Heel, Andre

2018-05-01

Electrochemical performance of ceramic (Ni-free) SOFC anodes based on La0.2Sr0.7TiO3-δ (LST) and Gd0.1Ce0.9O1.95-δ (CGO) is thoroughly investigated. Microstructures and compositions are systematically varied around the percolation thresholds of both phases by modification of phase volume fractions, particle size distributions and firing temperature. Differential impedance spectroscopy was performed while varying gas composition, electrical potential and operating temperature, which allows determining four distinct electrode processes. Significant anode impedances are measured at low frequencies, which in contrast to the literature cannot be linked with gas concentration impedance. The dominant low frequency process (∼1 Hz) is attributed to the chemical capacitance. Combined EIS and microstructure investigations show that the chemical capacitance correlates inversely with the available surface area of CGO, indicating CGO surface reactions as the kinetic limitation for the dominant anode process and for the associated chemical capacitance. In anodes with a fine-grained microstructure this limitation is significantly smaller, which results in an impressive power output as high as 0.34 Wcm-2. The anodes show high redox stability by not only withstanding 30 isothermal redox cycles, but even improving the performance. Hence, compared to conventional Ni-cermet anodes the new LST-CGO material represents an interesting alternative with much improved redox-stability.

Porous Silicon–Carbon Composite Materials Engineered by Simultaneous Alkaline Etching for High-Capacity Lithium Storage Anodes

International Nuclear Information System (INIS)

Sohn, Myungbeom; Kim, Dae Sik; Park, Hyeong-Il; Kim, Jae-Hun; Kim, Hansu

2016-01-01

Highlights: • A porous Si–C anode is obtained by alkaline etching of a non-porous Si–C composite. • The pores in the carbon frame are created by simultaneous etching of Si and carbon. • The cycle life is greatly improved after the alkaline treatment. • The porous Si–C composite electrode shows high dimensional stability during cycling. - Abstract: Porous silicon–carbon (Si–C) composite materials have attracted a great deal of attention as high-performance anode materials for Li-ion batteries (LIBs), but their use suffers from the complex and limited synthetic routes for their preparation. Herein we demonstrate a scalable and nontoxic method to synthesize porous Si–C composite materials by means of simultaneous chemical etching of Si and carbon phases using alkaline solution. The resulting porous Si–C composite material showed greatly improved cycle performance, good rate capability, and high dimensional stability during cycling. Porous Si–C electrode showed an expansion of the height by about 22% after the first lithiation and only 16% after the first cycle. The material synthesis concept and scalable simultaneous etching approach presented here represent a means of improving the electrochemical properties of Si-based porous anode materials for use in commercial LIBs.

Nanostructured Si/TiC composite anode for Li-ion batteries

International Nuclear Information System (INIS)

Zeng, Z.Y.; Tu, J.P.; Yang, Y.Z.; Xiang, J.Y.; Huang, X.H.; Mao, F.; Ma, M.

2008-01-01

Si/TiC nanocomposite anode was synthesized by a surface sol-gel method in combination with a following heat-treatment process. Through this process, nanosized Si was homogeneously distributed in a titanium carbide matrix. The electrochemically less active TiC working as a buffer matrix successfully prevented Si from cracking/crumbling during the charging/discharging process. The interspaces in the Si/TiC nanocomposite could offer convenient channels for Li ions to react with active Si. The Si/TiC composite exhibited a reversible charge/discharge capacity of about 1000 mAh g -1 with average discharge capacity fading of 1.8 mAh g -1 (0.18%) from 2nd to 100th cycle, indicating its excellent cyclability when used as anode materials for lithium-ion batteries

Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Jin Zhang

2017-01-01

Full Text Available The copper oxide (CuO nanowires/functionalized graphene (f-graphene composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group “–(CH25COOH”, and the CuO nanowires (NWs were well dispersed in the f-graphene sheets. When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g−1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes.

Infiltrated SrTiO₃:FeCr‐based Anodes for Metal‐Supported SOFC

DEFF Research Database (Denmark)

Blennow Tullmar, Peter; Reddy Sudireddy, Bhaskar; Persson, Åsa Helen

2013-01-01

The concept of using electronically conducting anode backbones with subsequent infiltration of electrocatalytic active materials has been used to develop an alternative solid oxide fuel cell (SOFC) design based on a ferritic stainless steel support. The anode backbone consists of a composite made...

Embedded Si/Graphene Composite Fabricated by Magnesium-Thermal Reduction as Anode Material for Lithium-Ion Batteries.

Science.gov (United States)

Zhu, Jiangliu; Ren, Yurong; Yang, Bo; Chen, Wenkai; Ding, Jianning

2017-12-16

Embedded Si/graphene composite was fabricated by a novel method, which was in situ generated SiO 2 particles on graphene sheets followed by magnesium-thermal reduction. The tetraethyl orthosilicate (TEOS) and flake graphite was used as original materials. On the one hand, the unique structure of as-obtained composite accommodated the large volume change to some extent. Simultaneously, it enhanced electronic conductivity during Li-ion insertion/extraction. The MR-Si/G composite is used as the anode material for lithium ion batteries, which shows high reversible capacity and ascendant cycling stability reach to 950 mAh·g -1 at a current density of 50 mA·g -1 after 60 cycles. These may be conducive to the further advancement of Si-based composite anode design.

Crystalline and Amorphous Phosphorus – Carbon Nanotube Composites as Promising Anodes for Lithium-Ion Batteries

KAUST Repository

Smajic, Jasmin

2016-05-04

Battery research has been going full steam and with that the search for alternative anodes. Among many proposed electrode materials, little attention has been given to phosphorus. Phosphorus boasts the third highest gravimetric charge capacity and the highest volumetric charge capacity of all elements. Because of that, it would be an attractive battery anode material were it not for its poor cyclability with significant capacity loss immediately after the first cycle. This is known to be the consequence of considerable volume changes of phosphorus during charge/discharge cycles. In this work, we propose circumventing this issue by mixing amorphous red phosphorus with carbon nanotubes. By employing a non-destructive sublimation-deposition method, we have synthesized composites where the synergetic effect between phosphorus and carbon nanotubes allow for an improvement in the electrochemical performance of battery anodes. In fact, it has been shown that carbon nanotubes can act as an effective buffer to phosphorus volumetric expansions and contractions during charging and discharging of the half-cells [1]. By modifying the synthesis parameters, we have also been able to change the degree of crystallinity of the phosphorus matrix in the composites. In fact, the less common phase of red phosphorus, named fibrous phosphorus, was obtained, and that explains some of the varying electrochemical performances observed in the composites. Overall, it is found that a higher surface area of amorphous phosphorus allows for a better anode material when using single-walled carbon nanotubes as fillers.

Automotive assessment of carbon-silicon composite anodes and methods of fabrication

Science.gov (United States)

Karulkar, Mohan; Blaser, Rachel; Kudla, Bob

2015-01-01

To assess the potential of carbon silicon composite anodes for automotive applications, C-Si anodes were fabricated and certain improvements employed. The use of a PVDF buffer layer is demonstrated for the first time with a C-Si composite material. The buffer layer increases adhesion by 89%, and increases capacity by 50-80%. Also, a limited capacity range is employed to improve cycle life by up to 200%, and enable currents as high as 2 mA cm-1. The combined use of a buffer layer and limited capacity range has not been reported before. A model is also presented for comparing C-Si performance with real-world automotive targets from USABC, including energy density, power density, specific energy, and specific power. The analysis reveals a capacity penalty that arises from pairing C-Si with a traditional cathode (NCA), and which prevents the cell from meeting all targets. Scenarios are presented in which a higher-capacity cathode (250 mAh g-1) allows all targets to be hypothetically met.

SiOx/C composite from rice husks as an anode material for lithium-ion batteries

International Nuclear Information System (INIS)

Ju, Yanming; Tang, Joel A.; Zhu, Kai; Meng, Yuan; Wang, Chunzhong; Chen, Gang; Wei, Yingjin; Gao, Yu

2016-01-01

Highlights: • Rice husks were utilized to prepare SiO x /C as an anode material for lithium ion battery. • SiO x /C composite was prepared by a two-step fire process. • SiO x /C contains low valence silicon owing to thermal treatment at argon/hydrogen atmosphere. • SiO x /C exhibits a high specific capacity of nearly 600 mAh g −1 at 100 mA g −1 current density after 100 cycles. - Abstract: SiO x /C composite material derived directly from agricultural rice husk byproducts through an economically viable and environmentally benign approach has been explored to be used as an anode for rechargeable lithium batteries. Rice husks were converted into a SiO x /C composite directly by heat treatment under argon/hydrogen atmosphere, at a temperature of 900 °C. The composite contains SiO x surrounded by an amorphous carbon matrix. A steady state reversible capacity of nearly 600 mAh g −1 was delivered at 100 mA g −1 current density after 100 cycles. The improved performance of the SiO x /C composite anode over other agricultural byproduct derived carbon materials is believed to be due to the presence of low valence silicon. The filth-to-wealth conversion of rice husks to battery material is a highly energy efficient process with great economic and environmental benefits.

Electrochemical performance of SnO{sub 2}/modified graphite composite material as anode of lithium ion battery

Energy Technology Data Exchange (ETDEWEB)

Wang, Hong-Qiang [Guangxi Key Laboratory of Low Carbon Energy Materials, School of Chemical and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004 (China); Hubei Key Laboratory for Processing and Application of Catalytic Materials, Huanggang Normal University, Huanggang 438000 (China); Yang, Guan-Hua; Huang, You-Guo; Zhang, Xiao-Hui; Yan, Zhi-Xiong [Guangxi Key Laboratory of Low Carbon Energy Materials, School of Chemical and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004 (China); Li, Qing-Yu, E-mail: liqingyu62@126.com [Guangxi Key Laboratory of Low Carbon Energy Materials, School of Chemical and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004 (China)

2015-11-01

In this report, we synthesized SnO{sub 2}/modified graphite anode composite material by a simple reflux method using SnCl{sub 4}·5H{sub 2}O as tin source and modified graphite as carbon source. The as-obtained composite was investigated with the help of X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic cycling tests. The results show that the composite has a wave-shaped fold structure and the SnO{sub 2} nanoparticles on it have an average size of about 50 nm. Compared to pure modified graphite, the SnO{sub 2}/modified graphite exhibits a better electrochemical performance with a reversible specific capacity of 581.7 mAh g{sup −1} after 80 cycles, owing to high mechanical stress and elasticity of modified graphite could hinder the volume effect of SnO{sub 2} nanoparticles during the Li{sup +} insertion/extraction process. All these favourable characters reveal that the composite is a great potential anode material in high-performance lithium ion batteries. - Highlights: • A simple synthetic method of SnO{sub 2}/modified graphite composite as anode. • The as-prepared composite with layered structure alleviates the huge reunion of SnO{sub 2}. • The composite exhibits a good capacity retention rate of 85.8% after 25 cycles.

Synthesis and electrochemical characteristics of Sn-Sb-Ni alloy composite anode for Li-ion rechargeable batteries

International Nuclear Information System (INIS)

Guo Hong; Zhao Hailei; Jia Xidi; Qiu Weihua; Cui Fenge

2007-01-01

Micro-scaled Sn-Sb-Ni alloy composite was synthesized from oxides of Sn, Sb and Ni via carbothermal reduction. The phase composition and electrochemical properties of the Sn-Sb-Ni alloy composite anode material were studied. The prepared alloy composite electrode exhibits a high specific capacity and a good cycling stability. The lithiation capacity was 530 mAh g -1 in the first cycle and maintained at 370-380 mAh g -1 in the following cycles. The good electrochemical performance may be attributed to its relatively large particle size and multi-phase characteristics. The former reason leads to the lower surface impurity and thus the lower initial capacity loss, while the latter results in a stepwise lithiation/delithiation behavior and a smooth volume change of electrode in cycles. The Sn-Sb-Ni alloy composite material shows a good candidate anode material for the rechargeable lithium ion batteries

Stable cyclic performance of nickel oxide–carbon composite anode for lithium-ion batteries

International Nuclear Information System (INIS)

Susantyoko, Rahmat Agung; Wang, Xinghui; Fan, Yu; Xiao, Qizhen; Fitzgerald, Eugene; Pey, Kin Leong; Zhang, Qing

2014-01-01

Nickel oxide (NiO) directly grown on nickel foam is regarded as a promising lithium ion battery anode material which shows good cyclic and rate performances with a theoretical specific capacity of 718 mA h g −1 . In this study, we demonstrated a carbon-incorporated NiO anode (NiO–C) with a capacity per unit area of 2.11 mA h cm −2 and 1.76 mA h cm −2 at 0.2 C and 0.5 C rates, respectively, fabricated by thermal oxidation of carbon coated nickel foam. The specific capacity of our NiO–C composite samples at 0.5 C rate is found to be typically 389.16 mA h g −1 , with a stable cyclic performance up to more than 100 cycles. This remarkable performance is apparently superior to the control samples of pure NiO samples. The improved performance is contributed to carbon incorporation which serves as a fluent channel for electrons and a flexible network preventing NiO nanostructures from structural deformation during charge and discharge processes. The advantage of using our approach is the easy preparation of the NiO–C composite using a simple two-step process: chemical vapor deposition of ethanol and annealing in air. - Highlights: • We demonstrated a directly grown NiO–C anode on nickel foam substrate. • NiO–C anode was made using simple processes: CVD of ethanol and annealing in air. • The NiO–C anode has a stable cycle life up to 102 cycles. • It has an acceptable areal capacity (1.76 mA h cm −2 at 0.5 C rate) for practical use. • Carbon provides electrons path and buffering matrix preventing NiO pulverization

Mesostructured niobium-doped titanium oxide-carbon (Nb-TiO2-C) composite as an anode for high-performance lithium-ion batteries

Science.gov (United States)

Hwang, Keebum; Sohn, Hiesang; Yoon, Songhun

2018-02-01

Mesostructured niobium (Nb)-doped TiO2-carbon (Nb-TiO2-C) composites are synthesized by a hydrothermal process for application as anode materials in Li-ion batteries. The composites have a hierarchical porous structure with the Nb-TiO2 nanoparticles homogenously distributed throughout the porous carbon matrix. The Nb content is controlled (0-10 wt%) to investigate its effect on the physico-chemical properties and electrochemical performance of the composite. While the crystalline/surface structure varied with the addition of Nb (d-spacing of TiO2: 0.34-0.36 nm), the morphology of the composite remained unaffected. The electrochemical performance (cycle stability and rate capability) of the Nb-TiO2-C composite anode with 1 wt% Nb doping improved significantly. First, a full cut-off potential (0-2.5 V vs. Li/Li+) of Nb-doped composite anode (1 wt%) provides a higher energy utilization than that of the un-doped TiO2-C anode. Second, Nb-TiO2-C composite anode (1 wt%) exhibits an excellent long-term cycle stability (100% capacity retention, 297 mAh/g at 0.5 C after 100 cycles and 221 mAh/g at 2 C after 500 cycles) and improved rate-capability (192 mAh/g at 5 C), respectively (1 C: 150 mA/g). The superior electrochemical performance of Nb-TiO2-C (1 wt%) could be attributed to the synergistic effect of improved electronic conductivity induced by optimal Nb doping (1 wt%) and lithium-ion penetration (high diffusion kinetics) through unique pore structures.

Fabrication and Characterization of SnO2/Graphene Composites as High Capacity Anodes for Li-Ion Batteries

Directory of Open Access Journals (Sweden)

Abirami Dhanabalan

2013-11-01

Full Text Available Tin-oxide and graphene (TG composites were fabricated using the Electrostatic Spray Deposition (ESD technique, and tested as anode materials for Li-ion batteries. The electrochemical performance of the as-deposited TG composites were compared to heat-treated TG composites along with pure tin-oxide films. The heat-treated composites exhibited superior specific capacity and energy density than both the as-deposited TG composites and tin oxide samples. At the 70th cycle, the specific capacities of the as-deposited and post heat-treated samples were 534 and 737 mA·h/g, respectively, and the corresponding energy densities of the as-deposited and heat-treated composites were 1240 and 1760 W·h/kg, respectively. This improvement in the electrochemical performance of the TG composite anodes as compared to the pure tin oxide samples is attributed to the synergy between tin oxide and graphene, which increases the electrical conductivity of tin oxide and helps alleviate volumetric changes in tin-oxide during cycling.

Methods for making anodes for lithium ion batteries

Science.gov (United States)

Xu, Wu; Canfield, Nathan L.; Zhang, Ji-Guang; Liu, Wei; Xiao, Jie; Wang, Deyu; Yang, Z. Gary

2015-05-26

Methods for making composite anodes, such as macroporous composite anodes, are disclosed. Embodiments of the methods may include forming a tape from a slurry including a substrate metal precursor, an anode active material, a pore-forming agent, a binder, and a solvent. A laminated structure may be prepared from the tape and sintered to produce a porous structure, such as a macroporous structure. The macroporous structure may be heated to reduce a substrate metal precursor and/or anode active material. Macroporous composite anodes formed by some embodiments of the disclosed methods comprise a porous metal and an anode active material, wherein the anode active material is both externally and internally incorporated throughout and on the surface of the macroporous structure.

Electrochemical performance of Si@TiN composite anode synthesized in a liquid ammonia for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Tu, Jiguo; Wang, Wei [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Jiao, Shuqiang, E-mail: sjiao@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Hou, Jungang; Huang, Kai [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhu, Hongmin, E-mail: hzhu@metall.ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

2012-10-15

High-efficiency Si@TiN composite anode was synthesized by a homogeneous reduction reaction in the liquid ammonia, then calcinated at 950 Degree-Sign C for 2 h in vacuum. The crystal structure and morphology of the obtained in-situ coated composites were characterized by XRD, FESEM. The results showed that the micron-sized Si particles were almost coated by the TiN nanoparticles with the average size of 50 nm, while the morphology of Si@TiN composite was almost unchanged over 50 discharge-charge cycles. The electrochemical performances of Si@TiN composite anode were studied by galvanostatic discharge-charge tests, cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The CV curves showed that the two redox peaks remained stable and were attributed to the alloying/dealloying process of Li with active Si particles. It could be seen from the EIS curves that the charge transfer resistance (R{sub ct}) for fresh was larger than that for the 50th cycle, which was mainly because the electrons and Li ions conducted on the electrode surface more difficultly for fresh. The cycle stability of the as-prepared Si@TiN composite anode was investigated, with the result showing that the cycling performance was stable and optimal at a rate of 0.2 C. The initial charge capacity was as high as 3226.99 mAh g{sup -1}, which was kept as 467.02 mAh g{sup -1} over 50 cycles. -- Highlights: Black-Right-Pointing-Pointer Si@TiN composite anode was synthesized in-situ in a liquid ammonia. Black-Right-Pointing-Pointer The size of TiN nanoparticles was about 50 nm. Black-Right-Pointing-Pointer The initial charge capacity was as high as 3226.99 mAh g{sup -1}.

What makes lithium substituted polyacrylic acid a better binder than polyacrylic acid for silicon-graphite composite anodes?

Science.gov (United States)

Hays, Kevin A.; Ruther, Rose E.; Kukay, Alexander J.; Cao, Pengfei; Saito, Tomonori; Wood, David L.; Li, Jianlin

2018-04-01

Lithium substituted polyacrylic acid (LiPAA) has previously been demonstrated as a superior binder over polyacrylic acid (PAA) for Si anodes, but from where does this enhanced performance arise? In this study, full cells are assembled with PAA and LiPAA based Si-graphite composite anodes that dried at temperatures from 100 °C to 200 °C. The performance of full cells containing PAA based Si-graphite anodes largely depend on the secondary drying temperature, as decomposition of the binder is correlated to increased electrode moisture and a rise in cell impedance. Full cells containing LiPAA based Si-graphite composite electrodes display better Coulombic efficiency than those with PAA, because of the electrochemical reduction of the PAA binder. This is identified by attenuated total reflectance Fourier transform infrared spectrometry and observed gassing during the electrochemical reaction. Coulombic losses from the PAA and Si SEI, along with depletion of the Si capacity in the anode results in progressive underutilization of the cathode and full cell capacity loss.

Graphene nanoribbon and nanostructured SnO2 composite anodes for lithium ion batteries.

Science.gov (United States)

Lin, Jian; Peng, Zhiwei; Xiang, Changsheng; Ruan, Gedeng; Yan, Zheng; Natelson, Douglas; Tour, James M

2013-07-23

A composite made from graphene nanoribbons (GNRs) and tin oxide (SnO2) nanoparticles (NPs) is synthesized and used as the anode material for lithium ion batteries (LIBs). The conductive GNRs, prepared using sodium/potassium unzipping of multiwall carbon nanotubes, can boost the lithium storage performance of SnO2 NPs. The composite, as an anode material for LIBs, exhibits reversible capacities of over 1520 and 1130 mAh/g for the first discharge and charge, respectively, which is more than the theoretical capacity of SnO2. The reversible capacity retains ~825 mAh/g at a current density of 100 mA/g with a Coulombic efficiency of 98% after 50 cycles. Further, the composite shows good power performance with a reversible capacity of ~580 mAh/g at the current density of 2 A/g. The high capacity, good power performance and retention can be attributed to uniformly distributed SnO2 NPs along the high-aspect-ratio GNRs. The GNRs act as conductive additives that buffer the volume changes of SnO2 during cycling. This work provides a starting point for exploring the composites made from GNRs and other transition metal oxides for lithium storage applications.

Si/C composite lithium-ion battery anodes synthesized using silicon nanoparticles from porous silicon

International Nuclear Information System (INIS)

Park, Jung-Bae; Lee, Kwan-Hee; Jeon, Young-Jun; Lim, Sung-Hwan; Lee, Sung-Man

2014-01-01

The synthesis of Si nanoparticles by ultrasonication processing of porous Si powder and a novel method for preparing a high-capacity Si/C composite using this technique is reported. The porous Si powder is prepared by selectively etching the silicide phase of a Ti 24 Si 76 alloy consisting of Si and silicide phases. The particle size of the nanocrystalline Si is determined by the crystallite size of the Si and silicide phases in the alloy powder. Ultrasonication of the porous Si obtained from the mechanically alloyed Ti 24 Si 76 alloy generates nanocrystalline Si particles of size about 5 nm. Growth of the Si and silicide phases in the alloy is induced by annealing of the mechanically alloyed sample, with a consequent increase in the size of the Si particles obtained after ultrasonication. Application of the ultrasonication process to the fabrication of Si/C composite anode materials generates nanometer-scale Si particles in situ that are distributed in the matrix. Analysis of the phases obtained and evaluation of the distribution of the nanometer-scale Si particles in the composites via XRD/TEM measurements show that the nanometer-scale Si particles are effectively synthesized and uniformly distributed in the carbon matrix, leading to enhanced electrochemical performance of the Si/C composites

Deposition of Ni-CGO composite anodes by electrostatic assisted ultrasonic spray pyrolysis method

International Nuclear Information System (INIS)

Chen, J.-C.; Chang, C.-L.; Hsu, C.-S.; Hwang, B.-H.

2007-01-01

Deposition of composite films of Ni and Gd-doped ceria was carried out using the electrostatic assisted ultrasonic spray pyrolysis method for the first time. The composite films were highly homogeneous, as revealed by element mapping via energy-dispersive spectrometry. Scanning electron microscope examinations revealed that deposition temperature and electric field strength had profound influence on resultant microstructure, while composition of the precursor solution had little effect. A highly porous cauliflower structure ideal for solid oxide fuel cell anode performance was obtained with a deposition temperature of 450 deg. C under an electric field introduced by an applied voltage of 12 kV. Films obtained with a lower deposition temperature of 250 deg. C or a higher applied voltage of 15 kV resulted in denser films with low porosity, while lower applied voltages of 7 or 5 kV resulted in thinner or discontinuous films due to the insufficient electrostatic attraction on the aerosol droplets. As revealed by AC impedance measurement, the area specific resistances of the Ni-CGO anode with porous cauliflower structure were rather low and a value of 0.09 Ω cm 2 at 550 deg. C was obtained

Vacuum-Assisted Self-Assembly of Polymer Derived Siliconoxycarbide-Graphene Composite as Li-ion Battery Anode

Science.gov (United States)

David, Lamuel; Singh, Gurpreet

2013-03-01

Exfoliated graphene oxide (GO) and polysiloxane were blended and pyrolyzed to synthesize freestanding SiOC-graphene composite papers (~ 10 μm thick). The structural and chemical characterization of the composite prepared with varying ceramic concentrations was carried out using electron microscopy, XRD, XPS and FT-infrared spectroscopy. High resolution microscopy images shows layer by layer stacking of GO sheets and an increase in interlayer spacing was observed by X-ray analysis. FTIR peaks at 3400 cm-1 (O-H), 1720 cm-1 (C =O), 1600 cm-1 (graphene), 3056 cm-1 (Si-CH =CH2) and 1034 cm-1 (Si-O-Si) confirmed the successful functionalization of SiOC with GO. Thermo-gravimetric analysis showed enhanced thermodynamic stability of the composite paper up to at least 700 °C in flowing air. The SiOC/Graphene composite paper anodes showed stable electrochemical capacity of approx. 500 mAh/g which was twice that of free standing graphene anodes. The average coulombic efficiency (second cycle onwards) was observed to be approx. 97%.

Stable silicon/3D porous N-doped graphene composite for lithium-ion battery anodes with self-assembly

Science.gov (United States)

Tang, Xiaofu; Wen, Guangwu; Song, Yan

2018-04-01

We fabricate a novel 3D N-doped graphene/silicon composite for lithium-ion battery anodes, with Si nanoparticles uniformly dispersed and thoroughly embedded in the N-doped graphene matrix. The favorable structure of the composite results in a BET surface area and an average mesopore diameter of 189.2 m2 g-1 and 3.82 nm, respectively. The composite delivers reversible capacities as high as 1132 mA h g-1 after 100 cycles under a current of 5 A g-1 and 1017 mA h g-1 after 200 cycles at 1 A g-1, and exhibits an improved rate capability. The present approach shows promise for the preparation of other high-performance anode materials for lithium-ion batteries.

Electrodeposited Germanium/Carbon Composite as an Anode Material for Lithium Ion Batteries

International Nuclear Information System (INIS)

Kim, Sang-Wan; Ngo, Duc Tung; Heo, Jaeyeong; Park, Choong-Nyeon; Park, Chan-Jin

2017-01-01

Highlights: • Electrodeposition was applied for the synthesis of Ge/C composite. • High coulombic efficiency of ∼85% in the first cycle was attained for Ge/C composite. • Full cell of Ge/C-LiCoO 2 exhibits excellent electrochemical performance, without pre-lithiation of Ge/C. - Abstract: We demonstrate the synthesis of nano Ge/C composite using a facile and cost-effective electrochemical deposition method, and its application as an anode material in Li-ion batteries. Nano Ge/C composite is electrodeposited directly on Cu foil in ethylene glycol containing GeCl 4 and carbon black. The Ge particles with an average size of ∼20 nm are uniformly covered with carbon. Compared with the pure Ge electrode, the Ge/C electrode exhibits a higher first reversible capacity of 1224 mA g −1 , and maintains a capacity of 1095 mAh g −1 at 0.1C over 50 cycles. Even at the high rate of 2C, the capacity of the Ge/C electrode is still high at 972 mAh g −1 . The presence of carbon black and pores in the Ge/C electrode improves the conductivity of the electrode, and mitigates the stress inside the electrode by supplying buffer volume, leading to the enhanced electrochemical characteristics of the electrode. Further, the full Li-ion cell composed of Ge/C anode and LiCoO 2 cathode exhibits good cyclability, rate capability, and coulombic efficiency.

Interweaved Si@C/CNTs and CNFs composites as anode materials for Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Zhang, Miao [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Hou, Xianhua, E-mail: houxh@scnu.edu.cn [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Engineering Research Center of Materials and Technology for Electrochemical Energy Storage Ministry of Education, Guangzhou 510006 (China); Wang, Jie; Li, Min [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Hu, Shejun [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Engineering Research Center of Materials and Technology for Electrochemical Energy Storage Ministry of Education, Guangzhou 510006 (China); Shao, Zongping [Nanjing University of Technology, College of Chemistry and Chemical Engineering, Nanjing 210009 (China); Liu, Xiang [Institute of Advanced Materials, Nanjing University of Technology, Nanjing 210009 (China)

2014-03-05

Graphical abstract: In summary, a serious of high-energy wet ball milling, closed spray drying and subsequent chemical vapor deposition methods were introduced successfully to fabricated novel Si@C/CNTs and CNFs composites with carbon nanotubes and carbon nanofibres interweaved with carbon coated silicon spherical composites as superior anodes in lithium-ion batteries. The core-shell structure of Si@C composites can accommodate the volume change of electrode during charge and discharge. Meanwhile, the citric acid pyrolyzed carbon was coated on the surface of the silicon perfectly and constructs the connection network of nano silicon particles. Moreover, the carbon nanotubes and carbon nanofibres, which is interweaved with nano-silicon, also allows high electrical conductivity, improved solid–electrolyte interface formation and structural integrity. Compared with pure silicon and Si@C composites, the novel Si@C/CNTs and CNFs composites had the best combination of reversible capacity and cycleablity, and this anode materials exhibited excellent electrochemical performance. The Si/C composite had a fairly high initial discharge capacity of 2168.7 mA h g{sup −1} with an efficiency of 73%, and the discharge capacity of the 50th cycle maintained surprisingly of 1194.9 mA h g{sup −1}. Meanwhile, spray drying and chemical vapor deposition are environmentally friendly, economical, and relatively high-yield method for the production of the Si@C/CNTs and CNFs composites in large quantities. Consequently, the novel Si@C/CNTs and CNFs composite electrodes may be a potential alternative to graphite for high energy density lithium ion batteries. Highlights: • The core/shell structured silicon/carbon composites were prepared by a facile way. • The as-prepared Si@C/CNTs and CNFs composites shows excellent electrochemical performance. • The preparation method has mild experiment conditions and high production rate. • The structure benefited electronic transfer and

Synthesis and Performance of Tungsten Disulfide/Carbon (WS2/C) Composite as Anode Material

Science.gov (United States)

Yuan, Zhengyong; Jiang, Qiang; Feng, Chuanqi; Chen, Xiao; Guo, Zaiping

2018-01-01

The precursors of an amorphous WS2/C composite were synthesized by a simple hydrothermal method using Na2WO4·2H2O and CH3CSNH2 as raw materials, polyethylene glycol as dispersant, and glucose as the carbon source. The as-synthesized precursors were further annealed at a low temperature in flowing argon to obtain the final materials (WS2/C composite). The structure and morphology of the WS2/C composite were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, and scanning electron microscopy. The electrochemical properties were tested by galvanostatic charge/discharge testing and alternating current (AC) impedance measurements. The results show that the as-prepared amorphous WS2/C composite features both high specific capacity and good cycling performance at room temperature within the potential window from 3.0 V to 0.01 V (versus Li+/Li) at current density of 100 mAg-1. The achieved initial discharge capacity was 1080 mAhg-1, and 786 mAhg-1 was retained after 170 cycles. Furthermore, the amorphous WS2/C composite exhibited a lower charge/discharge plateau than bare WS2, which is more beneficial for use as an anode. The cyclic voltammetry and AC impedance testing further confirmed the change in the plateau and the decrease in the charge transfer resistance in the WS2/C composite. The chemical formation process and the electrochemical mechanism of the WS2/C composite are also presented. The amorphous WS2/C composite can be used as a new anode material for future applications.

Nanoporous titanium niobium oxide and titanium tantalum oxide compositions and their use in anodes of lithium ion batteries

Science.gov (United States)

Dai, Sheng; Guo, Bingkun; Sun, Xiao-Guang; Qiao, Zhenan

2017-10-31

Nanoporous metal oxide framework compositions useful as anodic materials in a lithium ion battery, the composition comprising metal oxide nanocrystals interconnected in a nanoporous framework and having interconnected channels, wherein the metal in said metal oxide comprises titanium and at least one metal selected from niobium and tantalum, e.g., TiNb.sub.2-x Ta.sub.xO.sub.y (wherein x is a value from 0 to 2, and y is a value from 7 to 10) and Ti.sub.2Nb.sub.10-vTa.sub.vO.sub.w (wherein v is a value from 0 to 2, and w is a value from 27 to 29). A novel sol gel method is also described in which sol gel reactive precursors are combined with a templating agent under sol gel reaction conditions to produce a hybrid precursor, and the precursor calcined to form the anodic composition. The invention is also directed to lithium ion batteries in which the nanoporous framework material is incorporated in an anode of the battery.

Self-standing paper based anodes prepared from siliconcarbonitride-MoS2 composite for Li-ion battery applications

Science.gov (United States)

David, Lamuel; Singh, Gurpreet

2013-03-01

We study synthesis of free-standing polymer derived SiCN/ MoS2 composite paper anode for Li-ion battery application. This was achieved following a two-step approach: First, polysilazane was interfaced with exfoliated MoS2 nanosheets which upon pyrolysis resulted in SiCN/MoS2 composite. Second, dispersion of SiCN/MoS2 in isopropanol was vacuum filtered resulting in formation of a self-standing composite paper. Physical and chemical characterization of the composite was carried out by use of electron microscopy, Fourier transform infrared spectroscopy (FT-IR) and Thermo-gravimetric analysis (TGA). FT-IR data indicated complete conversion of polysilazane precursor to SiCN ceramic, while electron microscopy confirmed layered structure of the paper. Thermo-gravimetric analysis showed enhanced thermodynamic stability of the composite paper up to 800 °C. Electrochemical analysis of SiCN/MoS2 composite paper anodes showed that Li-ion can reversible intercalate in the voltage range of 0-2.5 V with a first cycle discharge capacity of 770 mAh/g at a current density of 100 mA/g.

Carbon Cryogel and Carbon Paper-Based Silicon Composite Anode Materials for Lithium-Ion Batteries

Science.gov (United States)

Woodworth, James; Baldwin, Richard; Bennett, William

2010-01-01

A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. 6 One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nano-foams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. 1-5 Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

Carbonate fuel cell anodes

Science.gov (United States)

Donado, Rafael A.; Hrdina, Kenneth E.; Remick, Robert J.

1993-01-01

A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process for production of the lithium ferrite containing anode by slipcasting.

Microbial community composition is unaffected by anode potential

KAUST Repository

Zhu, Xiuping

2014-01-21

There is great controversy on how different set anode potentials affect the performance of a bioelectrochemical system (BES). It is often reported that more positive potentials improve acclimation and performance of exoelectrogenic biofilms, and alter microbial community structure, while in other studies relatively more negative potentials were needed to achieve higher current densities. To address this issue, the biomass, electroactivity, and community structure of anodic biofilms were examined over a wide range of set anode potentials (-0.25, -0.09, 0.21, 0.51, and 0.81 V vs a standard hydrogen electrode, SHE) in single-chamber microbial electrolysis cells. Maximum currents produced using a wastewater inoculum increased with anode potentials in the range of -0.25 to 0.21 V, but decreased at 0.51 and 0.81 V. The maximum currents were positively correlated with increasing biofilm biomass. Pyrosequencing indicated biofilm communities were all similar and dominated by bacteria most similar to Geobacter sulfurreducens. Differences in anode performance with various set potentials suggest that the exoelectrogenic communities self-regulate their exocellular electron transfer pathways to adapt to different anode potentials. © 2013 American Chemical Society.

Microbial community composition is unaffected by anode potential

KAUST Repository

Zhu, Xiuping; Yates, Matthew D.; Hatzell, Marta C.; Rao, Hari Ananda; Saikaly, Pascal; Logan, Bruce E.

2014-01-01

There is great controversy on how different set anode potentials affect the performance of a bioelectrochemical system (BES). It is often reported that more positive potentials improve acclimation and performance of exoelectrogenic biofilms, and alter microbial community structure, while in other studies relatively more negative potentials were needed to achieve higher current densities. To address this issue, the biomass, electroactivity, and community structure of anodic biofilms were examined over a wide range of set anode potentials (-0.25, -0.09, 0.21, 0.51, and 0.81 V vs a standard hydrogen electrode, SHE) in single-chamber microbial electrolysis cells. Maximum currents produced using a wastewater inoculum increased with anode potentials in the range of -0.25 to 0.21 V, but decreased at 0.51 and 0.81 V. The maximum currents were positively correlated with increasing biofilm biomass. Pyrosequencing indicated biofilm communities were all similar and dominated by bacteria most similar to Geobacter sulfurreducens. Differences in anode performance with various set potentials suggest that the exoelectrogenic communities self-regulate their exocellular electron transfer pathways to adapt to different anode potentials. © 2013 American Chemical Society.

Fabrication of porous anodic alumina films by using two-step anodization process

International Nuclear Information System (INIS)

Xu Zhan; Zhou Bin; Xu Xiang; Wang Xiaoli; Wu Di; Shen Jun

2006-01-01

This article introduces the fabrication of the porous anodic alumina films which have ordered pore arrangement by using a two-step anodization process. The films have a parallel channel structure which nanopore diameter can be 20-100 nm, and depth can reach 50 μm. The change of pore structure in the first and second anodization, moving the alumina layer, widening process was analysed. The effect of the parameters such as different electrolytes, anodization temperature and the voltage on the nanopore structure was studied. The surface and profile structure through FE-SEM (field emission scanning electron microscope), the element composition in tiny area of the anodic aluminum oxide (AAO) surface were studied. The result indicates the pore diameter of AAO which is anodized in oxalic acid solution is larger than which anodized in sulfuric acid solution. The anodization temperature and voltage can enlarge the nanopore diameter of AAO in a range. (authors)

Electrotransport of Uranium from a Liquid Cadmium Anode to a Solid Cathode

International Nuclear Information System (INIS)

Ahluwalia, Rajesh K.; Hua, Thanh Q.

2002-01-01

During anodic dissolution of irradiated binary Experimental Breeder Reactor-II fuel, a portion of the electrorefined uranium collects in the underlying cadmium pool. It is periodically recovered by setting up a cell configuration in which the pool is made the anode and uranium is electrodeposited on a solid cathode mandrel. A theoretical model is used to determine the current structure of the liquid cadmium anode. The model is validated by comparing against the measured composition of the cathode deposits. Multinodal simulations are conducted to explain the bell shape of deposits observed with this mode of electrotransport. The simulations also determine the dependence of collection efficiency on the electrical charge passed that is functionally consistent with the experimental data. Finally, a simplified operating map of the electrorefiner is presented that can be used to determine the conditions for growing cathode deposits of target composition

Polymer-derived Ceramic SiCN-MoS2 Nanosheet Composite for Lithium Ion Battery Anodes

Science.gov (United States)

Bhandavat, Romil; Singh, Gurpreet

2012-02-01

We demonstrate synthesis of a novel SiCN-MoS2 nanosheet composite for use as Li-ion battery anode for high power applications. The nanosheet composite was prepared by thermal decomposition of polysilazane (SiCN precursor) on exfoliated MoS2 surfaces. The morphology and chemical structure was studied using a range of spectroscopy techniques that revealed a sidewall functionalization of exfoliated MoS2 by the polymeric precursor. The thermodynamic stability of SiCN-MoS2 nanosheets was also confirmed by thermo-gravimetric analysis (1000 degree C). Batteries assembled using MoS2-SiCN nanosheets as active anode material showed that lithium can be reversibly intercalated in the voltage range of 0-2.5 V with first cycle discharge capacity of 620 mAh/g at a current density of 100 mA/g.

Application of anodizing and CAR processes for manufacturing Al/Al{sub 2}O{sub 3} composite

Energy Technology Data Exchange (ETDEWEB)

Jamaati, Roohollah, E-mail: r.jamaatikenari@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Toroghinejad, Mohammad Reza; Najafizadeh, Abbas [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2010-06-25

In this study, an anodizing process with different conditions was used to grow four different thicknesses of alumina on the surface of aluminum strips. Then, a continual annealing and roll-bonding (CAR) process was done to produce an aluminum matrix composite dispersed with four different volume fractions of alumina particles. The results demonstrate that when the number of cycles was increased, the distribution of alumina particles in the aluminum matrix improved, the particles became finer, and the tensile strength of the composites increased. The microstructure of the fabricated composites after 8 CAR cycles also showed an excellent distribution of alumina particles in the matrix. Moreover, it was observed that increasing alumina quantities through longer anodizing times enhanced the tensile strength of the composite to become 1.65 times higher than that of the monolithic aluminum produced by the same method, while negligible reductions were observed in the elongation value. Fracture surfaces after tensile tests were observed by scanning electron microscopy (SEM) to investigate the failure mode. Observations reveal that the failure mode in both CAR-processed composites and monolithic aluminum was the typical ductile fracture showing deep equiaxed dimples.

An Amorphous Carbon Nitride Composite Derived from ZIF-8 as Anode Material for Sodium-Ion Batteries.

Science.gov (United States)

Fan, Jing-Min; Chen, Jia-Jia; Zhang, Qian; Chen, Bin-Bin; Zang, Jun; Zheng, Ming-Sen; Dong, Quan-Feng

2015-06-08

An composite comprising amorphous carbon nitride (ACN) and zinc oxide is derived from ZIF-8 by pyrolysis. The composite is a promising anode material for sodium-ion batteries. The nitrogen content of the ACN composite is as high as 20.4 %, and the bonding state of nitrogen is mostly pyridinic, as determined by X-ray photoelectron spectroscopy (XPS). The composite exhibits an excellent Na(+) storage performance with a reversible capacity of 430 mA h g(-1) and 146 mA h g(-1) at current densities of 83 mA g(-1) and 8.33 A g(-1) , respectively. A specific capacity of 175 mA h g(-1) was maintained after 2000 cycles at 1.67 A g(-1) , with only 0.016 % capacity degradation per cycle. Moreover, an accelerating rate calorimetry (ARC) test demonstrates the excellent thermal stability of the composite, with a low self heating rate and high onset temperature (210 °C). These results shows its promise as a candidate material for high-capacity, high-rate anodes for sodium-ion batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An excellent performance anode of ZnFe2O4/flake graphite composite for lithium ion battery

International Nuclear Information System (INIS)

Yao, Lingmin; Hou, Xianhua; Hu, Shejun; Tang, Xiaoqin; Liu, Xiang; Ru, Qiang

2014-01-01

Highlights: • ZnFe 2 O 4 /flake graphite composite was synthesized by hydrothermal method. • The ZnFe 2 O 4 /flake graphite anode demonstrated high initial coulombic efficiency of 87.7%. • The initial discharge /charge capacity was 848 mA h g −1 and 744 mA h g −1 . • The high capacity retention of 98% was obtained for the ZnFe 2 O 4 /flake graphite anode. -- Abstract: An approach of hydrothermal reaction for lithium ion battery was adopted, by which ZnFe 2 O 4 /flake graphite composites with excellent performance could be prepared as anode materials for lithium ion batteries. With nano-sized ZnFe 2 O 4 particles coating on the electrochemical active matrix of flake graphite, the special composites allowed improved electronic conductivity and constructed an expressway for the transport of charges and lithium ions. Thus the ZnFe 2 O 4 /flake graphite anode became a compromise between capacity and cycle ability. The initial discharge–charge capacity was 848 mA h g −1 and 744 mA h g −1 at a constant current density of 100 mA g −1 , respectively. As high as 87.7% of the initial coulombic efficiency was obtained. Additionally, the charge capacity maintained constantly in the range of 720–735 mA h g −1 in following cycles. And a high reversible charge capacity of 730 mA h g −1 could be attained after 100 cycles, with the reversible capacity retention of 98%

Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

International Nuclear Information System (INIS)

Jeon, Bup Ju; Lee, Joong Kee

2014-01-01

Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH 4 /SiH 4 mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH 4 and SiH 4 precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium

Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Jeon, Bup Ju [Department of Energy Resources, Shinhan University, 233-1, Sangpae-dong, Dongducheon, Gyeonggi-do, 483-777 (Korea, Republic of); Lee, Joong Kee, E-mail: leejk@kist.re.kr [Advanced Energy Materials Processing Laboratory, Center for Energy Convergence Research, Green City Technology Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

2014-03-25

Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH{sub 4}/SiH{sub 4} mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH{sub 4} and SiH{sub 4} precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium.

Investigation of mechanism of anode plasma formation in ion diode with dielectric anode

International Nuclear Information System (INIS)

Pushkarev, A.

2015-01-01

The results of investigation of the anode plasma formation in a diode with a passive anode in magnetic insulation mode are presented. The experiments have been conducted using the BIPPAB-450 ion accelerator (350–400 kV, 6–8 kA, 80 ns) with a focusing conical diode with B r external magnetic field (a barrel diode). For analysis of plasma formation at the anode and the distribution of the ions beam energy density, infrared imaging diagnostics (spatial resolution of 1–2 mm) is used. For analysis of the ion beam composition, time-of-flight diagnostics (temporal resolution of 1 ns) were used. Our studies have shown that when the magnetic induction in the A-C gap is much larger than the critical value, the ion beam energy density is close to the one-dimensional Child-Langmuir limit on the entire working surface of the diode. Formation of anode plasma takes place only by the flashover of the dielectric anode surface. In this mode, the ion beam consists primarily of singly ionized carbon ions, and the delay of the start of formation of the anode plasma is 10–15 ns. By reducing the magnetic induction in the A-C gap to a value close to the critical one, the ion beam energy density is 3–6 times higher than that calculated by the one-dimensional Child-Langmuir limit, but the energy density of the ion beam is non-uniform in cross-section. In this mode, the anode plasma formation occurs due to ionization of the anode material with accelerated electrons. In this mode, also, the delay in the start of the formation of the anode plasma is much smaller and the degree of ionization of carbon ions is higher. In all modes occurred effective suppression of the electronic component of the total current, and the diode impedance was 20–30 times higher than the values calculated for the mode without magnetic insulation of the electrons. The divergence of the ion beam was 4.5°–6°

Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

Science.gov (United States)

Surawathanawises, Krissada; Cheng, Xuanhong

2014-01-01

Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

Silicon Composite Anode Materials for Lithium Ion Batteries Based on Carbon Cryogels and Carbon Paper

Science.gov (United States)

Woodworth, James; Baldwin, Richard; Bennett, William

2010-01-01

A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nanofoams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

Photo-electrochemical and impedance investigation of passive layers grown anodically on titanium alloys

Energy Technology Data Exchange (ETDEWEB)

Oliveira, N.T.C. [Departamento de Quimica, Universidade Federal de Sao Carlos, CP 676, 13560-970 Sao Carlos, SP (Brazil); Biaggio, S.R. [Departamento de Quimica, Universidade Federal de Sao Carlos, CP 676, 13560-970 Sao Carlos, SP (Brazil); Piazza, S. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)]. E-mail: piazza@dicpm.unipa.it; Sunseri, C. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Di Quarto, F. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)

2004-10-15

The anodic behaviour of two titanium cast alloys, obtained by fusion in a voltaic arc under argon atmosphere, was analyzed in aerated aqueous solutions having different pH values. In all solutions the alloys, having nominal compositions Ti-50Zr at.% and Ti-13Zr-13Nb wt.%, displayed a valve-metal behaviour, owing to the formation of barrier-type oxide films. Passive films, grown potentiodynamically up to about 9 V, were investigated by photocurrent spectroscopy (PCS) and electrochemical impedance spectroscopy (EIS). These passive layers show photoactivity under anodic polarizations, with optical gaps close to 3.55 and 3.25 eV for the binary and the ternary alloy, respectively, independent of the anodizing electrolyte. Films grown on the binary alloy present insulating behaviour and anodic impedance spectra with one time constant; this was interpreted in terms of a single-layer mixed Ti-Zr oxide enriched in Ti with respect to the alloy composition. Also for the ternary alloy the results are consistent with the formation, upon anodization, of Ti-Nb-Zr mixed oxide films, but they display n-type semiconducting behaviour, owing to their poor content of ZrO{sub 2} groups.

Anode sheath transition in an anodic arc for synthesis of nanomaterials

Science.gov (United States)

Nemchinsky, V. A.; Raitses, Y.

2016-06-01

The arc discharge with ablating anode or so-called anodic arc is widely used for synthesis of nanomaterials, including carbon nanotubes and fullerens, metal nanoparticles etc. We present the model of this arc, which confirms the existence of the two different modes of the arc operation with two different anode sheath regimes, namely, with negative anode sheath and with positive anode sheath. It was previously suggested that these regimes are associated with two different anode ablating modes—low ablation mode with constant ablation rate and the enhanced ablation mode (Fetterman et al 2008 Carbon 46 1322). The transition of the arc operation from low ablation mode to high ablation mode is determined by the current density at the anode. The model can be used to self-consistently determine the distribution of the electric field, electron density and electron temperature in the near-anode region of the arc discharge. Simulations of the carbon arc predict that for low arc ablating modes, the current is driven mainly by the electron diffusion to the anode. For positive anode sheath, the anode voltage is close to the ionization potential of anode material, while for negative anode sheath, the anode voltage is an order of magnitude smaller. It is also shown that the near-anode plasma, is far from the ionization equilibrium.

Anode sheath transition in an anodic arc for synthesis of nanomaterials

International Nuclear Information System (INIS)

Nemchinsky, V A; Raitses, Y

2016-01-01

The arc discharge with ablating anode or so-called anodic arc is widely used for synthesis of nanomaterials, including carbon nanotubes and fullerens, metal nanoparticles etc. We present the model of this arc, which confirms the existence of the two different modes of the arc operation with two different anode sheath regimes, namely, with negative anode sheath and with positive anode sheath. It was previously suggested that these regimes are associated with two different anode ablating modes—low ablation mode with constant ablation rate and the enhanced ablation mode (Fetterman et al 2008 Carbon 46 1322). The transition of the arc operation from low ablation mode to high ablation mode is determined by the current density at the anode. The model can be used to self-consistently determine the distribution of the electric field, electron density and electron temperature in the near-anode region of the arc discharge. Simulations of the carbon arc predict that for low arc ablating modes, the current is driven mainly by the electron diffusion to the anode. For positive anode sheath, the anode voltage is close to the ionization potential of anode material, while for negative anode sheath, the anode voltage is an order of magnitude smaller. It is also shown that the near-anode plasma, is far from the ionization equilibrium. (paper)

Graphene oxide-multiwalled carbon nanotubes composite as an anode for lithium ion batteries

Directory of Open Access Journals (Sweden)

Majchrzycki Łukasz

2016-09-01

Full Text Available Nowadays reduced graphene oxide (rGO is regarded as a highly interesting material which is appropriate for possible applications in electrochemistry, especially in lithium-ion batteries (LIBs. Several methods were proposed for the preparation of rGO-based electrodes, resulting in high-capacity LIBs anodes. However, the mechanism of lithium storage in rGO and related materials is still not well understood. In this work we focused on the proposed mechanism of favorable bonding sites induced by additional functionalities attached to the graphene planes. This mechanism might increase the capacity of electrodes. In order to verify this hypothesis the composite of non-reduced graphene oxide (GO with multiwalled carbon nanotubes electrodes was fabricated. Electrochemical properties of GO composite anodes were studied in comparison with similarly prepared electrodes based on rGO. This allowed us to estimate the impact of functional groups on the reversible capacity changes. As a result, it was shown that oxygen containing functional groups of GO do not create, in noticeable way, additional active sites for the electrochemical reactions of lithium storage, contrary to what has been postulated previously.

Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

Science.gov (United States)

Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

2014-12-01

Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

Facile and large-scale preparation of sandwich-structured graphene-metal oxide composites as anode materials for Li-ion batteries

International Nuclear Information System (INIS)

Fang, Hongmei; Zhao, Li; Yue, Wenbo; Wang, Yuan; Jiang, Yang; Zhang, Yuan

2015-01-01

Graphene-based metal oxides are desirable as potential anode materials for lithium-ion batteries (LIBs) owing to their superior electrochemical properties. In this work, sandwich-structured graphene-metal oxide (ZnO, NiO) composites are facilely synthesized on a large scale through self-assembly of graphene oxide nanosheets and metal ammine complexes, and then thermal decomposition of the self-assembled products. ZnO or NiO nanoparticles with diameters of 5∼10 nm are immobilized between the layers of graphene nanosheets, which may provide the space for accommodating the volume change of metal oxides during cycles, and highly improve the electronic conductivity of the composites. Accordingly, these sandwich-structured composites exhibit enhanced electrochemical performances compared to metal oxide particles or stacked graphene nanosheets. This facile synthesis method is very suitable for the large-scale production of three-dimensional graphene-based composites as high-performance anodes for LIBs.

An Insoluble Titanium-Lead Anode for Sulfate Electrolytes

Energy Technology Data Exchange (ETDEWEB)

Ferdman, Alla

2005-05-11

The project is devoted to the development of novel insoluble anodes for copper electrowinning and electrolytic manganese dioxide (EMD) production. The anodes are made of titanium-lead composite material produced by techniques of powder metallurgy, compaction of titanium powder, sintering and subsequent lead infiltration. The titanium-lead anode combines beneficial electrochemical behavior of a lead anode with high mechanical properties and corrosion resistance of a titanium anode. In the titanium-lead anode, the titanium stabilizes the lead, preventing it from spalling, and the lead sheathes the titanium, protecting it from passivation. Interconnections between manufacturing process, structure, composition and properties of the titanium-lead composite material were investigated. The material containing 20-30 vol.% of lead had optimal combination of mechanical and electrochemical properties. Optimal process parameters to manufacture the anodes were identified. Prototypes having optimized composition and structure were produced for testing in operating conditions of copper electrowinning and EMD production. Bench-scale, mini-pilot scale and pilot scale tests were performed. The test anodes were of both a plate design and a flow-through cylindrical design. The cylindrical anodes were composed of cylinders containing titanium inner rods and fitting over titanium-lead bushings. The cylindrical design allows the electrolyte to flow through the anode, which enhances diffusion of the electrolyte reactants. The cylindrical anodes demonstrate higher mass transport capabilities and increased electrical efficiency compared to the plate anodes. Copper electrowinning represents the primary target market for the titanium-lead anode. A full-size cylindrical anode performance in copper electrowinning conditions was monitored over a year. The test anode to cathode voltage was stable in the 1.8 to 2.0 volt range. Copper cathode morphology was very smooth and uniform. There was no

High Performance Li4Ti5O12/Si Composite Anodes for Li-Ion Batteries

Directory of Open Access Journals (Sweden)

Chunhui Chen

2015-08-01

Full Text Available Improving the energy capacity of spinel Li4Ti5O12 (LTO is very important to utilize it as a high-performance Li-ion battery (LIB electrode. In this work, LTO/Si composites with different weight ratios were prepared and tested as anodes. The anodic and cathodic peaks from both LTO and silicon were apparent in the composites, indicating that each component was active upon Li+ insertion and extraction. The composites with higher Si contents (LTO:Si = 35:35 exhibited superior specific capacity (1004 mAh·g−1 at lower current densities (0.22 A·g−1 but the capacity deteriorated at higher current densities. On the other hand, the electrodes with moderate Si contents (LTO:Si = 50:20 were able to deliver stable capacity (100 mAh·g−1 with good cycling performance, even at a very high current density of 7 A·g−1. The improvement in specific capacity and rate performance was a direct result of the synergy between LTO and Si; the former can alleviate the stresses from volumetric changes in Si upon cycling, while Si can add to the capacity of the composite. Therefore, it has been demonstrated that the addition of Si and concentration optimization is an easy yet an effective way to produce high performance LTO-based electrodes for lithium-ion batteries.

In situ synthesis of α-MoO3/graphene composites as anode materials for lithium ion battery

International Nuclear Information System (INIS)

Liu, Chun-Ling; Wang, Yan; Zhang, Chen; Li, Xiao-Shan; Dong, Wen-Sheng

2014-01-01

The α-MoO 3 /graphene composites (MoO 3 /G) were prepared via an in situ hydrothermal synthesis. The composites were characterized using various characterization techniques including powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and the electrochemical performance test. The results show that these MoO 3 /G composites exhibit high capacity and good cycle stability when used as the lithium-ion battery anode. Among all the samples, the MoO 3 /G-27 reveals the best electrochemical performance with an initial charge capacity of 977.7 mAh g −1 at a current density of 50 mA g −1 , the first coulombic efficiency of 69.5%. After eighty cycles the electrode still maintains a capacity of 869.2 mAh g −1 , giving high capacity retention of 88.9%. The good electrochemical performance of the composite anode is close related to its structure, in which the MoO 3 nanobelts are not only homogeneously anchored on the surface but also embedded in the interlayer of the graphene sheets; hence the volume change and aggregation of the MoO 3 nanobelts during lithium ion insertion/extraction process can be effectively hindered. On the other hand, graphene itself is an electronic conductor; the graphene and MoO 3 nanobelts connect closely, which offers large electrode/electrolyte contacting area, short path length for Li + transporting during lithium insertion and extraction. - Highlights: • The α-MoO 3 /graphene composites were prepared via an in situ hydrothermal synthesis. • The MoO 3 /G-27 anode delivers an initial reversible capacity of 977.7 mAh g −1 . • After 80 cycles it has a reversible capacity of 869.2 mAh g −1 at 50 mA g −1

Effect of the anode feeding composition on the performance of a continuous-flow methane-producing microbial electrolysis cell.

Science.gov (United States)

Zeppilli, Marco; Villano, Marianna; Aulenta, Federico; Lampis, Silvia; Vallini, Giovanni; Majone, Mauro

2015-05-01

A methane-producing microbial electrolysis cell (MEC) was continuously fed at the anode with a synthetic solution of soluble organic compounds simulating the composition of the soluble fraction of a municipal wastewater. The MEC performance was assessed at different anode potentials in terms of chemical oxygen demand (COD) removal efficiency, methane production, and energy efficiency. As a main result, about 72-80% of the removed substrate was converted into current at the anode, and about 84-86% of the current was converted into methane at the cathode. Moreover, even though both COD removed and methane production slightly decreased as the applied anode potential decreased, the energy efficiency (i.e., the energy recovered as methane with respect to the energy input into the system) increased from 54 to 63%. Denaturing gradient gel electrophoresis (DGGE) analyses revealed a high diversity in the anodic bacterial community with the presence of both fermentative (Proteiniphilum acetatigenes and Petrimonas sulphurifila) and aerobic (Rhodococcus qingshengii) microorganisms, whereas only two microorganisms (Methanobrevibacter arboriphilus and Methanosarcina mazei), both assignable to methanogens, were observed in the cathodic community.

Highly reversible lead-carbon battery anode with lead grafting on the carbon surface

KAUST Repository

Yin, Jian; Lin, Nan; Zhang, Wenli; Lin, Zheqi; Zhang, Ziqing; Wang, Yue; Shi, Jun; Bao, Jinpeng; Lin, Haibo

2018-01-01

A novel C/Pb composite has been successfully prepared by electroless plating to reduce the hydrogen evolution and achieve the high reversibility of the anode of lead-carbon battery (LCB). The deposited lead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Because lead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogen evolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead. Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge–discharge reversibility, which is attributed to the good connection between carbon additives and lead that has been stuck on the surface of C/Pb composite during the preparation process. The addition of C/Pb composite maintains a solid anode structure with high specific surface area and power volume, and thereby, it plays a significant role in the highly reversible lead-carbon anode.

Highly reversible lead-carbon battery anode with lead grafting on the carbon surface

KAUST Repository

Yin, Jian

2018-03-27

A novel C/Pb composite has been successfully prepared by electroless plating to reduce the hydrogen evolution and achieve the high reversibility of the anode of lead-carbon battery (LCB). The deposited lead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Because lead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogen evolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead. Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge–discharge reversibility, which is attributed to the good connection between carbon additives and lead that has been stuck on the surface of C/Pb composite during the preparation process. The addition of C/Pb composite maintains a solid anode structure with high specific surface area and power volume, and thereby, it plays a significant role in the highly reversible lead-carbon anode.

Scalable synthesis of interconnected porous silicon/carbon composites by the Rochow reaction as high-performance anodes of lithium ion batteries.

Science.gov (United States)

Zhang, Zailei; Wang, Yanhong; Ren, Wenfeng; Tan, Qiangqiang; Chen, Yunfa; Li, Hong; Zhong, Ziyi; Su, Fabing

2014-05-12

Despite the promising application of porous Si-based anodes in future Li ion batteries, the large-scale synthesis of these materials is still a great challenge. A scalable synthesis of porous Si materials is presented by the Rochow reaction, which is commonly used to produce organosilane monomers for synthesizing organosilane products in chemical industry. Commercial Si microparticles reacted with gas CH3 Cl over various Cu-based catalyst particles to substantially create macropores within the unreacted Si accompanying with carbon deposition to generate porous Si/C composites. Taking advantage of the interconnected porous structure and conductive carbon-coated layer after simple post treatment, these composites as anodes exhibit high reversible capacity and long cycle life. It is expected that by integrating the organosilane synthesis process and controlling reaction conditions, the manufacture of porous Si-based anodes on an industrial scale is highly possible. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

International Nuclear Information System (INIS)

Abd-Elnaiem, Alaa M.; Mebed, A.M.; El-Said, Waleed Ahmed; Abdel-Rahim, M.A.

2014-01-01

Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes

Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

Energy Technology Data Exchange (ETDEWEB)

Abd-Elnaiem, Alaa M., E-mail: alaa.abd-elnaiem@science.au.edu.eg [KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Mebed, A.M. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Department of Physics, Faculty of Science, Al-Jouf University, Sakaka 2014 (Saudi Arabia); El-Said, Waleed Ahmed [Department of Chemistry, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Abdel-Rahim, M.A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

2014-11-03

Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes.

Anode pattern formation in atmospheric pressure air glow discharges with water anode

NARCIS (Netherlands)

Verreycken, T.; Bruggeman, P.J.; Leys, C.

2009-01-01

Pattern formation in the anode layer at a water electrode in atmospheric pressure glow discharges in air is studied. With increasing current a sequence of different anode spot structures occurs from a constricted homogeneous spot in the case of small currents to a pattern consisting of small

Fabrication of Si Nanoparticles@Carbon Fibers Composites from Natural Nanoclay as an Advanced Lithium-Ion Battery Flexible Anode

Directory of Open Access Journals (Sweden)

Sainan Liu

2018-04-01

Full Text Available In this paper, a cost-effective strategy for fabricating silicon-carbon composites was designed to further improve the electrochemical performance and commercialization prospects of Si anodes for lithium-ion batteries (LIBs. Silicon-carbon fibers (CFs were prepared by loading Si nanoparticles (SiNPs on interconnected carbon fibers via an electrospinning technique (SiNPs@CFs. The Si nanoparticles were obtained by the reduction reaction of natural clay minerals. As a flexible anode for LIBs, the SiNPs@CFs anode demonstrated a reversible capacity of 1238.1 mAh·g−1 and a capacity retention of 77% after 300 cycles (in contrast to the second cycle at a current density of 0.5 A·g−1. With a higher current density of 5.0 A·g−1, the electrode showed a specific capacity of 528.3 mAh·g−1 after 1000 cycles and exhibited a superior rate capability compared to Si nanoparticles. The excellent electrochemical properties were attributed to the construction of flexible electrodes and the composite comprising carbon fibers, which lessened the volume expansion and improved the conductivity of the system.

A novel high performance composite anode with in situ growth of Fe-Ni alloy nanoparticles for intermediate solid oxide fuel cells

International Nuclear Information System (INIS)

Li, Jingcheng; Yu, Yan; Yin, Yi-Mei; Zhou, Ning; Ma, Zi-Feng

2017-01-01

Highlights: • A composite anode with endogenous Fe-Ni alloy nanoparticles has been prepared. • The redox reversibility of the anode has been confirmed by XRD. • The E_a of H_2 oxidation at the anode is much smaller than that at Ni-YSZ anode. • A ScSZ supported cell achieves MPD of 0.71 Wcm"−"2 and R_p of 0.16 Ω cm"2 at 800 °C. • The single cell shows stable output during 105 h testing at 800 °C 0.7 V in wet H_2". - Abstract: A redox reversible composite anode with Fe-Ni alloy nanoparticles in situ growth on SrLaFeO_4-type and LaFeO_3-type oxide substrates has been prepared for intermediate temperature solid oxide fuel cell (IT-SOFC) by reducing perovskite precursor La_0_._4Sr_0_._6Fe_0_._7_5Ni_0_._1Nb_0_._1_5O_3_-_δ (LSFNNb) in wet H_2 at 900 °C for 1 h. The anode has shown an excellent electrochemical catalytic activity for oxidation of hydrogen with much smaller E_a (25.1 ∼ 68.9 kJ mol"−"1) than the value (>160 kJ mol"−"1) at Ni-YSZ anode. A scandium stabilized zirconia (ScSZ) electrolyte supported SOFC with the anode achieves maximum power densities of 0.71, 0.52, 0.35, and 0.21 W cm"−"2 at 800, 750, 700 and 650 °C, respectively in wet H_2 (3% H_2O), and the corresponding R_p of 0.16, 0.21, 0.35, and 0.60 Ω cm"2 under OCV. Moreover, the single cell shows stable power output during ∼105 h operation at 800 °C under 0.7 V in wet H_2 after a initial degradation, indicating that R-LSFNNb is an excellent candidate as anode of IT-SOFC.

Rotating anode X-ray source

International Nuclear Information System (INIS)

Wittry, D.B.

1979-01-01

A rotating anode x-ray source is described which consists of a rotary anode disc including a target ring and a chamber within the anode disc. Liquid is evaporated into the chamber from the target ring to cool the target and a method is provided of removing the latent heat of the vapor. (U.K.)

A mesoporous WO3−X/graphene composite as a high-performance Li-ion battery anode

International Nuclear Information System (INIS)

Liu, Fei; Kim, Jong Gu; Lee, Chul Wee; Im, Ji Sun

2014-01-01

Graphical abstract: The highly flexible and conductive graphene layer can enhance electron transfer, protect metal oxides against disintegration and aggregation and buffer the strain induced by volume expansion during cycles. The mesoporous surface layer provides an open network for Li+ diffusion. - Highlights: • Novel cocktail effects of 2D mesoporous WO 3−X /graphene for lithium ion battery. • New approach for lithium ion battery by easy and unique synthesis method. • Mechanism study with proper data for understanding a reaction on anode surface. - Abstract: A novel mesoporous WO 3−X /graphene composite was developed. This material allowed rapid electron and Li + ion diffusion when used as a Li-ion battery (LIB) anode material. Remarkably, the graphene support protected WO 3−X from changing volume during the electrochemical cycling process; this process generally induces capacity loss. The current work describes a high-performance anode material for LIB that has highly dense WO 3−X , as well as high capacity, rate capability and stability

Synthesis and electrochemical performance of mesoporous SiO{sub 2}–carbon nanofibers composite as anode materials for lithium secondary batteries

Energy Technology Data Exchange (ETDEWEB)

Hyun, Yura; Choi, Jin-Yeong [Department of Chemistry, Keimyung University (Korea, Republic of); Park, Heai-Ku [Department of Chemical Engineering, Keimyung University (Korea, Republic of); Bae, Jae Young [Department of Chemistry, Keimyung University (Korea, Republic of); Lee, Chang-Seop, E-mail: surfkm@kmu.ac.kr [Department of Chemistry, Keimyung University (Korea, Republic of)

2016-10-15

Highlights: • Mesoporous SiO{sub 2}–carbon nanofibers composite synthesized on Ni foam without any binder. • This composite was directly applied as anode material of Li secondary batteries. • Showed the highest initial (2420 mAh/g) and discharging (2092 mAh/g) capacity. • This material achieved a retention rate of 86.4% after 30 cycles. - Abstract: In this study, carbon nanofibers (CNFs) and mesoporous SiO{sub 2}–carbon nanofibers composite were synthesized and applied as the anode materials in lithium secondary batteries. CNFs and mesoporous SiO{sub 2}–CNFs composite were grown via chemical vapor deposition method with iron-copper catalysts. Mesoporous SiO{sub 2} materials were prepared by sol–gel method using tetraethylorthosilicate as the silica source and cetyltrimethylammoniumchloride as the template. Ethylene was used as the carbon source and passes into a quartz reactor of a tube furnace heated to 600 °C, and the temperature was maintained at 600 °C for 10 min to synthesize CNFs and mesoporous SiO{sub 2}–CNFs composite. The electrochemical characteristics of the as-prepared CNFs and mesoporous SiO{sub 2}–CNFs composite as the anode of lithium secondary batteries were investigated using a three-electrode cell. In particular, the mesoporous SiO{sub 2}–CNFs composites synthesized without binder after depositing mesoporous SiO{sub 2} on Ni foam showed the highest charging and discharging capacity and retention rate. The initial capacity (2420 mAh/g) of mesoporous SiO{sub 2}–CNFs composites decreased to 2092 mAh/g after 30 cycles at a retention rate of 86.4%.

Silver-incorporated composites of Fe2O3 carbon nanofibers as anodes for high-performance lithium batteries

Science.gov (United States)

Zou, Mingzhong; Li, Jiaxin; Wen, WeiWei; Chen, Luzhuo; Guan, Lunhui; Lai, Heng; Huang, Zhigao

2014-12-01

Composites of Ag-incorporated carbon nanofibers (CNFs) confined with Fe2O3 nanoparticles (Ag-Fe2O3/CNFs) have been synthesized through an electrospinning method and evaluated as anodes for lithium batteries (LIBs). The obtained Ag-Fe2O3/CNF anodes show good LIB performance with a capacity of 630 mAh g-1 tested at 800 mA g-1 after 150 cycles with almost no capacity loss and superb rate performance. The obtained properties for Ag-Fe2O3/CNF anodes are much better than Fe2O3/CNF anodes without Ag-incorporating. In addition, the low-temperature LIB performances for Ag-Fe2O3/CNF anodes have been investigated for revealing the enhanced mechanism of Ag-incorporating. The superior electrochemical performances of the Ag-Fe2O3/CNFs are associated with a synergistic effect of the CNF matrix and the highly conducting Ag incorporating. This unique configuration not only facilitates electron conduction especially at a relative temperature, but also maintains the structural integrity of active materials. Meanwhile, the related analysis of the AC impedance spectroscopy and the corresponding hypothesis for DC impedance confirm that such configuration can effectively enhance the charge-transfer efficiency and the lithium diffusion coefficient. Therefore, CNF-supported coupled with Ag incorporating synthesis supplied a promising route to obtain Fe2O3 based anodes with high-performance LIBs especially at low temperature.

Effect of ageing in the electrolyte and water on porous anodic films on zirconium

Energy Technology Data Exchange (ETDEWEB)

Muratore, F.; Hashimoto, T.; Skeldon, P., E-mail: peter.skeldon@manchester.ac.uk; Thompson, G.E.

2011-06-15

Highlights: Porous anodic films are formed on zirconium consisting of nanotubes embedded in a fluoride-rich matrix. {yields}Ageing in the formation electrolyte transforms the films from porous to nanotubular. Ageing causes losses of zirconium and fluorine, due to dissolution of the matrix. Ageing in water has negligible influence on the film composition and the film morphology. - Abstract: The present study demonstrates the significant influence of ageing in the formation electrolyte on the morphology and composition of anodic films grown on zirconium in 0.35 M ammonium fluoride in glycerol. Ageing after anodizing, by immersion in the electrolyte for 1 h, is shown to promote a transition from a porous to a nanotubular morphology, due to the dissolution of the fluoride-rich intratubular material in which the nanotubes are embedded. The morphological change is accompanied by a significant loss of zirconium and fluorine from the film. In contrast, ageing in deionized water has little influence on the films.

Self-assembly silicon/porous reduced graphene oxide composite film as a binder-free and flexible anode for lithium-ion batteries

International Nuclear Information System (INIS)

Tang, H.; Zhang, Y.J.; Xiong, Q.Q.; Cheng, J.D.; Zhang, Q.; Wang, X.L.; Gu, C.D.; Tu, J.P.

2015-01-01

A Si/porous reduced graphene oxide (rGO) composite film synthesized by evaporation and leavening method are developed as a high-performance anode material for lithium ion batteries. The porous structure as buffer base can effectively release the volume expansion of the silicon particles, increase the electrical conductivity and reduce the transfer resistance of Li ions. The Si/porous rGO composite film presents high specific capacity and good cycling stability (1261 mA h g −1 at 50 mA g −1 up to 70 cycles), as well as enhanced rate capability. This approach to prepare such a unique structure is a low-cost and facile route for the silicon-based anode materials

Fabrication and Characterization of Graded Anodes for Anode-Supported Solid Oxide Fuel Cells by Tape Casting and Lamination

DEFF Research Database (Denmark)

Beltran-Lopez, J.F.; Laguna-Bercero, M.A.; Gurauskis, Jonas

2014-01-01

Graded anodes for anode-supported solid oxide fuel cells (SOFCs) are fabricated by tape casting and subsequent cold lamination of plates using different compositions. Rheological parameters are adjusted to obtain stable suspensions for tape casting. The conditions for the tape casting and laminat......Graded anodes for anode-supported solid oxide fuel cells (SOFCs) are fabricated by tape casting and subsequent cold lamination of plates using different compositions. Rheological parameters are adjusted to obtain stable suspensions for tape casting. The conditions for the tape casting...... and lamination will be described. Flexural strength of the reduced cermets measured using three-point bending configuration is 468±37MPa. The graded anode supports are characterized by scanning electron microscope observations, mercury porosimetry intrusion, and resistivity measurements, showing an adequate...... of tapes at room temperature without using plasticizers. This is made by the combination of two different binders with varying Tg (glass transition temperature) which resulted in plastic deformation at room temperature. Those results indicate that the proposed process is a cost-effective method...

One-step solution combustion synthesis of Fe{sub 2}O{sub 3}/C nano-composites as anode materials for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Li, Peiyang; Deng, Jiachun; Li, Ying [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Liang, Wei, E-mail: liangwei@tyut.edu.cn [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Kun [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Kang, Litao, E-mail: kangltxy@gmail.com [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zeng, Shaozhong; Yin, Shanhui; Zhao, Zhigang [Chery Automobile Co. Ltd., Wuhu 241006 (China); Liu, Xuguang; Yang, Yongzhen [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Gao, Feng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)

2014-03-25

Highlights: • Fe{sub 2}O{sub 3}/C composite anode materials were prepared by a solution combustion process. • The carbon content could be adjusted by regulating the ratio of oxidizer/fuel. • The Fe{sub 2}O{sub 3}/C composite showed capacity 470 mA h g{sup −1} at the 80th cycle at 125 mA g{sup −1}. -- Abstract: This article describes a one-step solution combustion route (within 30 min at 350 °C in air) to prepare Fe{sub 2}O{sub 3} anode materials for lithium ion batteries (LIBs) from Fe(NO{sub 3}){sub 3}⋅9H{sub 2}O solution with citric acid. XRD, SEM-EDX and TEM showed that the product consisted a mixture of nano-sized α-Fe{sub 2}O{sub 3} and γ-Fe{sub 2}O{sub 3} crystals that agglomerated into porous particles. Significantly, in situ formed carbon could be introduced into the product (i.e., Fe{sub 2}O{sub 3}/C nano-composites) by simply increasing the dosage of citric acid in the precursor solution. The as-prepared Fe{sub 2}O{sub 3}/C nano-composite exhibited high reversible capacities of 470 and 419 mA h g{sup −1} at the 80th and 200th cycles with a current density of 125 mA g{sup −1}, which are much higher than those of counterparts without carbon (i.e., Fe{sub 2}O{sub 3} nano-particles). Comparison experiments correlated with the performance improvement of Fe{sub 2}O{sub 3}/C nano-composites with in situ formed carbon, well-developed mesopores and relatively high specific surface areas.

Cu particles decorated pomegranate-structured SnO2@C composites as anode for lithium ion batteries with enhanced performance

International Nuclear Information System (INIS)

Wen, WeiWei; Zou, Mingzhong; Feng, Qian; Li, Jiaxin; Guan, Lunhui; Lai, Heng; Huang, Zhigao

2015-01-01

In this paper, homogeneous composites of pomegranate-structured SnO 2 @C/Cu have been prepared by a simple hydrothermal reaction coupled with wet-chemical reduction, and directly used as anode materials for lithium ion batteries (LIBs). These SnO 2 @C/Cu anodes with an unique architecture show good LIB performance with a capacity of 660 mAh g −1 tested at 600 mA g −1 after 50 cycles and good rate performance at room temperature. Compared with the pure SnO 2 and SnO 2 @C, SnO 2 @C/Cu anodes exhibit much better low-temperature electrochemical performance including reversible capacity, cycling performance, and rate performance. The good LIB performance of SnO 2 @C/Cu anodes should be associated with carbon shell and the conducting Cu particles. This unique configuration can prevent the agglomeration of active materials and facilitate electron conduction especially at a relative low temperature, and obtain the capacity stability in cycling process for LIBs.

Electrochemical characterization of silicon/graphene/MWCNT hybrid lithium-ion battery anodes produced via RF magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Toçoğlu, Ubeyd, E-mail: utocoglu@sakarya.edu.tr; Hatipoğlu, Gizem; Alaf, Miraç; Kayış, Fuat; Akbulut, Hatem

2016-12-15

Graphical abstract: Silicon/graphene/MWCNT hybrid composite anodes were produced via RF magnetron sputtering technique. CR2016 type coin cells were assembled for electrochemical characterization of anodes. Electrochemical characterizations of anodes were conducted via galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy techniques. - Highlights: • Silicon/graphene/MWCNT hybrid negative lithium ion battery anodes were produced via magnetron sputtering. • Structural and electrochemical characterizations of composite anodes were conducted comprehensively. • The capacity values exhibited by composite anodes were found to be almost more than two times compared to thin film anodes after 100 cycles. - Abstract: In this study it was aimed to enhance cycling performance of silicon lithium ion battery anodes via producing flexible Silicon/Graphene/MWCNT composite structures. The volumetric expansions, which are the primary obstacle that hinders the practical usage of silicon anodes, were tried to suppress using flexible graphene/MWCNT paper substrates. Moreover to achieve lightweight and high electrical conductive anodes, the advantage of graphene was aimed to be exploited. Silicon/graphene/MWCNT flexible composite anodes were produced via radio frequency (RF) magnetron sputtering technique. Graphene/MWCNT papers were produced with vacuum filtration technique as substrate for sputtering process. At coating process of papers constant sputtering power was applied. Phase analysis was conducted with X-ray diffraction (XRD) technique and Raman spectroscopy. Field emission scanning electron microscopy (FESEM). Cyclic voltammetry (CV) tests were carried out to reveal reversible reactions between silicon and lithium. Galvanostatic charge/discharge technique was employed to determine the cyclic performance of anodes. Electrochemical impedance spectroscopy technique was used to understand the relation between cyclic performance and

Electrochemical characterization of silicon/graphene/MWCNT hybrid lithium-ion battery anodes produced via RF magnetron sputtering

International Nuclear Information System (INIS)

Toçoğlu, Ubeyd; Hatipoğlu, Gizem; Alaf, Miraç; Kayış, Fuat; Akbulut, Hatem

2016-01-01

Graphical abstract: Silicon/graphene/MWCNT hybrid composite anodes were produced via RF magnetron sputtering technique. CR2016 type coin cells were assembled for electrochemical characterization of anodes. Electrochemical characterizations of anodes were conducted via galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy techniques. - Highlights: • Silicon/graphene/MWCNT hybrid negative lithium ion battery anodes were produced via magnetron sputtering. • Structural and electrochemical characterizations of composite anodes were conducted comprehensively. • The capacity values exhibited by composite anodes were found to be almost more than two times compared to thin film anodes after 100 cycles. - Abstract: In this study it was aimed to enhance cycling performance of silicon lithium ion battery anodes via producing flexible Silicon/Graphene/MWCNT composite structures. The volumetric expansions, which are the primary obstacle that hinders the practical usage of silicon anodes, were tried to suppress using flexible graphene/MWCNT paper substrates. Moreover to achieve lightweight and high electrical conductive anodes, the advantage of graphene was aimed to be exploited. Silicon/graphene/MWCNT flexible composite anodes were produced via radio frequency (RF) magnetron sputtering technique. Graphene/MWCNT papers were produced with vacuum filtration technique as substrate for sputtering process. At coating process of papers constant sputtering power was applied. Phase analysis was conducted with X-ray diffraction (XRD) technique and Raman spectroscopy. Field emission scanning electron microscopy (FESEM). Cyclic voltammetry (CV) tests were carried out to reveal reversible reactions between silicon and lithium. Galvanostatic charge/discharge technique was employed to determine the cyclic performance of anodes. Electrochemical impedance spectroscopy technique was used to understand the relation between cyclic performance and

PEO of pre-anodized Al–Si alloys: Corrosion properties and influence of sealings

Energy Technology Data Exchange (ETDEWEB)

Mohedano, M., E-mail: marta.mohedano@hzg.de [Helmholtz Zentrum Geesthacht, Magnesium Innovation Centre, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A. [Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid (Spain)

2015-08-15

Highlights: • A356 gravity-cast and rheocast pre-anodized aluminium alloys were coated by PEO. • Different sealing techniques were applied after the coating process. • Iron-rich constituents of the substrate occlude the continuity of the porous anodic film. • PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. • Post-treatments improved both hydrophobic and corrosion properties. - Abstract: Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

Ni modified ceramic anodes for direct-methane solid oxide fuel cells

Science.gov (United States)

Xiao, Guoliang; Chen, Fanglin

2016-01-19

In accordance with certain embodiments of the present disclosure, a method for fabricating a solid oxide fuel cell is described. The method includes synthesizing a composition having a perovskite present therein. The method further includes applying the composition on an electrolyte support to form an anode and applying Ni to the composition on the anode.

One-step synthesis of continuous free-standing Carbon Nanotubes-Titanium oxide composite films as anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Gao, Hongxu; Hou, Feng; Wan, Zhipeng; Zhao, Sha; Yang, Deming; Liu, Jiachen; Guo, Anran; Gong, Yuxuan

2015-01-01

Highlights: • CNTs/TiO 2 compoiste films synthesized are continuous and free-standing. • The film can be directly used as flexible, binder-free Lithium-Ion Battery electrode. • The CNTs/TiO 2 electrodes exhibit excellent rate capacity and cyclic stability. • Our strategy is readily applicable to fabricate other CNTs-based composite films. - Abstract: Continuous free-standing Carbon Nanotubes (CNTs)/Titanium oxide (TiO 2 ) composite films were fabricated in a vertical CVD gas flow reactor with water sealing by the One-Step Chemical Vapor Deposition (CVD) approach. The composite films consist of multiple layers of conductive carbon nanotube networks with titanium oxide nanoparticles decorating on carbon nanotube surface. The as-synthesized flexible and transferrable composite films show excellent electrochemical properties, when the content of tetrabutyl titanate is 19.0 wt.%, which can be promising as binder-free anodes for Lithium-Ion Battery (LIB) applications. It demonstrates remarkably high rate capacity of 150 mAh g −1 , as well as excellent high rate cyclic stability over 500 cycles (current density of 3000 mA g −1 ). Such observations can be attributed to the relatively larger surface area and pore volume comparing with pristine CNT films. Great potentials of CNTs/TiO 2 composite films for large-scale production and application in energy devices were shown

Effect of solvent composition on the limiting current of anodic dissolution of tungsten in aqueous-ethanol solutions of alkali

International Nuclear Information System (INIS)

Konoplyantseva, N.A.; L'vova, L.A.; Davydov, A.D.; AN SSSR, Moscow. Inst. Ehlektrokhimii)

1987-01-01

The effect of quantitative composition of solvent on tungsten anodic dissolution in aqueous-ethanol solutions of KOH is studied. It is shown that with an increase in ethanol content in aqueous-ethanol solutions of alkali the limiting current of tungsten anodic dissolution decreases. An increase in KOH concentration in certain limits (in ethanol solutions it is the range between 0.75 and 1.0 M KOH) results in the increase of the limiting current; with further increase in solution concentration the limiting current decreases, which can be related to the change of the limiting stage. An assumption is made that total reaction of tungsten anodic dissolution and the main reasons for the limiting current appearance do not change from aqueous to aqueous-ethanol and ethanol solutions of alkali

Flexible organic light-emitting diodes consisting of a platinum doped indium tin oxide anode

International Nuclear Information System (INIS)

Hsu, C-M; Huang, C-Y; Cheng, H-E; Wu, W-T

2009-01-01

This paper demonstrates that a flexible organic light-emitting diode (OLED) with a platinum (Pt)-doped indium tin oxide (ITO) anode could show superior electro-optical characteristics to those of a conventional device. The threshold voltage and turn-on voltage of an OLED device consisting of an aluminium/lithium fluoride/tris(8-hydroxyquinoline) aluminium/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4, 4'-diamine/Pt-doped ITO/ITO structure were reduced by 1.2 V and 0.8 V, respectively. Current efficiency was found improved for a driving voltage of less than 6.5 V as a result of the enhanced hole-injection rate, attributed mainly to the elevated surface work function and partly reduced surface roughness of ITO by the incorporated Pt atoms in the ITO matrix.

Insight into effects of graphene in Li4Ti5O12/carbon composite with high rate capability as anode materials for lithium ion batteries

International Nuclear Information System (INIS)

Ding, Y.; Li, G.R.; Xiao, C.W.; Gao, X.P.

2013-01-01

Li 4 Ti 5 O 12 /carbon composites have shown promising high rate capability as anode materials for lithium ion batteries. In this paper, unique effects of graphene in Li 4 Ti 5 O 12 /carbon composites on electrochemical performances are focused by means of comparing Li 4 Ti 5 O 12 /graphene with Li 4 Ti 5 O 12 /conductive carbon black (CCB) and Li 4 Ti 5 O 12 . The investigated anode materials are synthesized by a facile hydrothermal method. The amount of graphene or CCB in the Li 4 Ti 5 O 12 /carbon composites is about 3 wt% measured by thermogravimetric (TG) analysis. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that Li 4 Ti 5 O 12 /graphene consists of small sized Li 4 Ti 5 O 12 nanocrystals supported on graphene nanosheets, while Li 4 Ti 5 O 12 /CCB comprises Li 4 Ti 5 O 12 nanocrystal aggregates coated nearly by graphited carbon. The electrochemical performances of these samples as anode materials for lithium ion batteries are investigated by galvanostatic charge–discharge method. Li 4 Ti 5 O 12 /graphene provides a superior rate capability. At the high current density of 1600 mA g −1 , the reversible capacity after 200 cycles is still more than 120 mAh g −1 , which is about 40% higher than that of Li 4 Ti 5 O 12 /CCB. Cyclic voltammetry (CV) demonstrates that stronger pseudocapacitive effect occurs on Li 4 Ti 5 O 12 /graphene than on Li 4 Ti 5 O 12 /CCB. This derived from the structure features that graphene-supported small Li 4 Ti 5 O 12 nanocrystals provide more surface active sites for the lithium ion insertion/extraction. The strong pseudocapacitive effect is responsible for the improvements of capacity and high-rate capability. Further, electrochemical impedance spectra (EIS) show that Li 4 Ti 5 O 12 /graphene electrode have lower charge transfer resistance and smaller diffusion impedance, indicating the obvious advantages in electrode kinetics over Li 4 Ti 5 O 12 and Li 4 Ti 5 O 12

Anodization and Optical Appearance of Sputter Deposited Al-Zr Coatings

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara

2014-01-01

of the anodized layer. The microstructure of the coating is found to influence the appearance of anodized layer owing to the presence of completely or partially dissolved second phases during anodizing process. Oxidation status of the second phase particles in the coatings affected the light absorption......Anodized Al alloy components are extensively used in various applications like architectural, decorative and automobiles for corrosion protection and/or decorative optical appearance. However, tailoring the anodized layer for specific optical appearance is limited due to variation in composition...... and microstructure of the commercial alloys, and even more difficult with recycled alloys. Sputter coating methods promise to control the chemical composition of the Al alloy surfaces and eventually modify the microstructure of the surfaces with heat treatments thus enabling the freedom on the substrate quality...

N-doped graphene/graphite composite as a conductive agent-free anode material for lithium ion batteries with greatly enhanced electrochemical performance

International Nuclear Information System (INIS)

Guanghui, Wu; Ruiyi, Li; Zaijun, Li; Junkang, Liu; Zhiguo, Gu; Guangli, Wang

2015-01-01

Graphical abstract: The study reported a novel N-doped graphene/graphite anode material for lithium ion batteries. The composite exhibits a largely enhanced electrochemical performance. The study also provides an attractive approach for the fabrication of various graphite-based materials for high power batteries. Display Omitted -- Highlights: • The paper developed a new N-doped graphene/graphite composite for lithium ion battery • The composite contains a three-dimensional graphene framework with rich of open pores • The hybrid offers a higher electrical conductivity when compared with pristine graphite • The hybrid electrode provides a greatly enhanced electrochemical performance • The study provides a prominent approach for fabrication of graphite-based materials -- ABSTRACT: Present graphite anode cannot meet the increasing requirement of electronic devices and electric vehicles due to its low specific capacity, poor cycle stability and low rate capability. The study reported a promising N-doped graphene/graphite composite as a conductive agent-free anode material for lithium ion batteries. Herein, graphite oxide and urea were dispersed in ultrapure water and partly reduced by ascorbic acid. Followed by mixing with graphite and hydrothermal treatment to produce graphene oxide/graphite hydrogel. The hydrogel was dried and finally annealed in Ar/H 2 to obtain N-doped graphene/graphite composite. The result shows that all of graphite particles was dispersed in three-dimensional graphene framework with a rich of open pores. The open pore accelerates the electrolyte transport. The graphene framework works as a conductive agent and graphite particle connector and improves the electron transfer. Electrical conductivity of the composite reaches 5912 S m −1 , which is much better than that of the pristine graphite (4018 S m −1 ). The graphene framework also acts as an expansion absorber in the anodes of lithium ion battery to relieve the large strains

Synthesis of Fe3O4 cluster microspheres/graphene aerogels composite as anode for high-performance lithium ion battery

Science.gov (United States)

Zhou, Shuai; Zhou, Yu; Jiang, Wei; Guo, Huajun; Wang, Zhixing; Li, Xinhai

2018-05-01

Iron oxides are considered as attractive electrode materials because of their capability of lithium storage, but their poor conductivity and large volume expansion lead to unsatisfactory cycling stability. We designed and synthesized a novel Fe3O4 cluster microspheres/Graphene aerogels composite (Fe3O4/GAs), where Fe3O4 nanoparticles were assembled into cluster microspheres and then embedded in 3D graphene aerogels framework. In the spheres, the sufficient free space between Fe3O4 nanoparticles could accommodate the volume change during cycling process. Graphene aerogel works as flexible and conductive matrix, which can not only significantly increase the mechanical stress, but also further improve the storage properties. The Fe3O4/GAs composite as an anode material exhibits high reversible capability and excellent cyclic capacity for lithium ion batteries (LIBs). A reversible capability of 650 mAh g-1 after 500 cycles at a current density of 1 A g-1 can be maintained. The superior storage capabilities of the composites make them potential anode materials for LIBs.

A facile strategy to construct binder-free flexible carbonate composite anode at low temperature with high performances for lithium-ion batteries

International Nuclear Information System (INIS)

Shi, Shaojun; Zhang, Ming; Deng, Tingting; Wang, Ting; Yang, Gang

2017-01-01

Graphical abstract: The schematic illustration of the strategy for preparations and the mechanism for the stability of structure Display Omitted -- Highlights: •A facile strategy is applied to construct flexible carbonate composite anode. •Carbon nano-fiber matrix serves as fast charge channel and efficient buffer. •High specific capacity of 958 mAh g −1 at 100 mA g −1 is obtained. •After 200 cycles at 1 A g −1 , there is not obvious capacity decline. •The mechanism for stress release is further analyzed. -- Abstract: High temperature is usually necessary for carbon modification or electrospinning to obtain flexible anode with excellent conductivity and stability. However, due to the unstable instinct of carbonate, it’s hard to obtain carbonate when any of the synthesis process undergoes high temperature treatment. Thus, a facile strategy is applied to construct binder-free flexible carbonate composite anode at low temperature with high electrochemical performances. The carbon nano-fiber matrix is first synthesized through electrospinning followed by a facile solvothermal process to in-situ grow carbonate on carbon nano-fibers to form a well combinative flexible anode. The carbon nano-fiber matrix serves not only as a fast channel for charge transfer, but also as an efficient buffer to release the stress resulting from the hysteresis of lithiation for carbonate particles during repeated charge/discharge cycles. Owing to the synergistic effect of carbon nano-fiber and the carbonate, the flexible anode exhibits high specific capacity of 958 mAh g −1 . And after 200 cycles at 1 A g −1 , no obvious capacity decline. The reaction mechanism for stress release is also well analyzed to display the merit of our strategy. It is considered as one of the most promising way to get binder-free flexible carbonate anode with remarkable properties.

Rational Design of Si@SiO2/C Composites Using Sustainable Cellulose as a Carbon Resource for Anodes in Lithium-Ion Batteries.

Science.gov (United States)

Shen, Dazhi; Huang, Chaofan; Gan, Lihui; Liu, Jian; Gong, Zhengliang; Long, Minnan

2018-03-07

In this work, we propose a novel and facile route for the rational design of Si@SiO 2 /C anode materials by using sustainable and environment-friendly cellulose as a carbon resource. To simultaneously obtain a SiO 2 layer and a carbon scaffold, a specially designed homogeneous cellulose solution and commercial Si nanopowder are used as the starting materials, and the cellulose/Si composite is directly assembled by an in situ regenerating method. Subsequently, Si@SiO 2 /C composite is obtained after carbonization. As expected, Si@SiO 2 is homogeneously encapsulated in the cellulose-derived carbon network. The obtained Si@SiO 2 /C composite shows a high reversible capacity of 1071 mA h g -1 at a current density of 420 mA g -1 and 70% capacity retention after 200 cycles. This novel, sustainable, and effective design is a promising approach to obtain high-performance and cost-effective composite anodes for practical applications.

Anode plasma and focusing reb diodes

International Nuclear Information System (INIS)

Goldstein, S.A.; Swain, D.W.; Hadley, G.R.; Mix, L.P.

1975-01-01

The use of electrical, optical, x-ray, and particle diagnostics to characterize the production of anode plasma and to monitor its influence on beam generation and focusing is reviewed. Studies using the Nereus accelerator show that after cathode turn-on, deposition of several kJ/gm on the anode is necessary before ions from hydrocarbons, adsorbed gases, and heavier metallic species are detected. The actual time at which ions are liberated depends on several factors, one of which is the specific heat of the anode substrate. Once formed, anode ions cross the A-K gap (with an energy equal to the diode voltage) and interact with the cathode to produce an axially peaked beam profile, a ''pinch'' which does not follow the critical current criterion. Experiments with externally generated anode plasma show that this type of pinch can be attracted to localized areas on the anode. Preliminary observations on Hydra indicate the anode plasma composition is similar to that on Nereus. The effect of this plasma on pinch dynamics currently is under investigation

Microwave Plasma Chemical Vapor Deposition of Nano-Structured Sn/C Composite Thin-Film Anodes for Li-ion Batteries

Energy Technology Data Exchange (ETDEWEB)

Stevenson, Cynthia; Marcinek, M.; Hardwick, L.J.; Richardson, T.J.; Song, X.; Kostecki, R.

2008-02-01

In this paper we report results of a novel synthesis method of thin-film composite Sn/C anodes for lithium batteries. Thin layers of graphitic carbon decorated with uniformly distributed Sn nanoparticles were synthesized from a solid organic precursor Sn(IV) tert-butoxide by a one step microwave plasma chemical vapor deposition (MPCVD). The thin-film Sn/C electrodes were electrochemically tested in lithium half cells and produced a reversible capacity of 440 and 297 mAhg{sup -1} at C/25 and 5C discharge rates, respectively. A long term cycling of the Sn/C nanocomposite anodes showed 40% capacity loss after 500 cycles at 1C rate.

New High-Energy Nanofiber Anode Materials

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiangwu [North Carolina State Univ., Raleigh, NC (United States); Fedkiw, Peter [North Carolina State Univ., Raleigh, NC (United States); Khan, Saad [North Carolina State Univ., Raleigh, NC (United States); Huang, Alex [North Carolina State Univ., Raleigh, NC (United States); Fan, Jiang [North Carolina State Univ., Raleigh, NC (United States)

2013-11-15

The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 μm or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

Stainless steel anodes for alkaline water electrolysis and methods of making

Science.gov (United States)

Soloveichik, Grigorii Lev

2014-01-21

The corrosion resistance of stainless steel anodes for use in alkaline water electrolysis was increased by immersion of the stainless steel anode into a caustic solution prior to electrolysis. Also disclosed herein are electrolyzers employing the so-treated stainless steel anodes. The pre-treatment process provides a stainless steel anode that has a higher corrosion resistance than an untreated stainless steel anode of the same composition.

Anodization of cast aluminium alloys produced by different casting methods

Directory of Open Access Journals (Sweden)

K. Labisz

2008-08-01

Full Text Available In this paper the usability of two casting methods, of sand and high pressure cast for the anodization of AlSi12 and AlSi9Cu3 aluminium cast alloys was investigated. With defined anodization parameters like electrolyte composition and temperature, current type and value a anodic alumina surface layer was produced. The quality, size and properties of the anodic layer was investigated after the anodization of the chosen aluminium cast alloys. The Alumina layer was observed used light microscope, also the mechanical properties were measured as well the abrasive wear test was made with using ABR-8251 equipment. The researches included analyze of the influence of chemical composition, geometry and roughness of anodic layer obtained on aluminum casts. Conducted investigations shows the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminum casting alloys, for example in the range of raising resistance on corrosion to achieve a suitable anodic surface layer on elements for increasing applications in the aggressive environment for example as materials on working building constructions, elements in electronics and construction parts in air and automotive industry.

Microwave Derived Facile Approach to Sn/Graphene Composite Anodes for, Lithium-Ion Batteries

International Nuclear Information System (INIS)

Beck, Faith R.; Epur, Rigved; Hong, Daeho; Manivannan, Ayyakkannu; Kumta, Prashant N.

2014-01-01

Graphical abstract: Tin particles embedded in graphene (G) sheet have been synthesized by microwave reduction of tin halide (SnCl 2 ) and graphite oxide (GO) followed by annealing in argon. The microwave reaction resulted in the formation of tin oxide embedded in graphene sheets. Annealing in argon at elevated temperatures initiated carbothermal reduction culminating in the formation of tin decorated graphene sheet composites that were employed as anodes for lithium-ion batteries. X-ray diffraction analysis of the final composite showed the presence of crystalline tin combined with a very small diffraction peak corresponding to (002) plane of graphite. Scanning electron microscopy (SEM) revealed decorated graphene layers with tin droplets. X-ray Photoelectron Spectroscopy (XPS) confirmed the presence of graphene and graphene oxide in the composite. Electrochemical cycling response indicated that the tin/graphene composite exhibited initial discharge capacities varying from 790 mAh/g to 850 mAh/g depending on the composition, while a stable reversible capacity of ∼500 mAh/g was achieved for optimized compositions when cycled at a current density of ∼100 mA/g in the voltage window of 0.02 to 1.2 V vs. Li + /Li. Carbon coating of the Sn/G composite ultimately achieved by decomposition of dextrose using microwave heating significantly improved the electrochemical cycling stability. - Highlights: • Tin embedded graphene sheets have been synthesized by microwave reduction. • Tin oxide and graphene formed was carbothermally reduced to Sn/graphene. • XPS confirmed presence of graphene and graphene oxide in the composite. • Electrochemical response indicated capacities in 790 mAh/g to 850 mAh/g range. • Carbon coated composite yielded stable reversible capacity ∼500 mAh/g. - Abstract: Tin particles embedded in graphene (G) sheets have been synthesized by microwave reduction of tin halide (SnCl 2 .2H 2 O) and graphite oxide (GO) followed by annealing in argon

Preparation of titanium dioxide films on etched aluminum foil by vacuum infiltration and anodizing

Energy Technology Data Exchange (ETDEWEB)

Xiang, Lian, E-mail: xianglian93@163.com; Park, Sang-Shik, E-mail: parkss@knu.ac.kr

2016-12-01

Highlights: • Al{sub 2}O{sub 3}–TiO{sub 2} composite films were prepared onto high voltage Al etching foil. • The coated and anodized samples showed multi-layer structures. • The capacitances of TiO{sub 2} coated samples showed an increase of 42%. • The increase in capacitance was mainly due to the Al–Ti composite layer. - Abstract: Al{sub 2}O{sub 3}–TiO{sub 2} (Al–Ti) composite oxide films are a promising dielectric material for future use in capacitors. In this study, TiO{sub 2} films were prepared on etched Al foils by vacuum infiltration. TiO{sub 2} films prepared using a sol–gel process were annealed at various temperatures (450, 500, and 550 °C) for different time durations (10, 30, and 60 min) for 4 cycles, and then anodized at 100 V. The specimens were characterized using X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy. The results show that the tunnels of the specimens feature a multi-layer structure consisting of an Al{sub 2}O{sub 3} outer layer, an Al–Ti composite oxide middle layer, and an aluminum hydrate inner layer. The electrical properties of the specimens, such as the withstanding voltage and specific capacitance, were also measured. Compared to specimens without TiO{sub 2} coating, the specific capacitances of the TiO{sub 2}-coated specimens are increased. The specific capacitance of the anode Al foil with TiO{sub 2} coating increased by 42% compared to that of a specimen without TiO{sub 2} coating when annealed at 550 °C for 10 min. These composite oxide films could enhance the specific capacitance of anode Al foils used in dielectric materials.

Silicon oxide based high capacity anode materials for lithium ion batteries

Science.gov (United States)

Deng, Haixia; Han, Yongbong; Masarapu, Charan; Anguchamy, Yogesh Kumar; Lopez, Herman A.; Kumar, Sujeet

2017-03-21

Silicon oxide based materials, including composites with various electrical conductive compositions, are formulated into desirable anodes. The anodes can be effectively combined into lithium ion batteries with high capacity cathode materials. In some formulations, supplemental lithium can be used to stabilize cycling as well as to reduce effects of first cycle irreversible capacity loss. Batteries are described with surprisingly good cycling properties with good specific capacities with respect to both cathode active weights and anode active weights.

A mesoporous WO{sub 3−X}/graphene composite as a high-performance Li-ion battery anode

Energy Technology Data Exchange (ETDEWEB)

Liu, Fei [C-Industry Incubation Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600 (Korea, Republic of); Kim, Jong Gu [C-Industry Incubation Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600 (Korea, Republic of); Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lee, Chul Wee [C-Industry Incubation Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600 (Korea, Republic of); University of Science and Technology (UST), Gajeong-ro, Yuseong-gu, Daejeon 305-333 (Korea, Republic of); Im, Ji Sun, E-mail: jsim@krict.re.kr [C-Industry Incubation Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600 (Korea, Republic of); University of Science and Technology (UST), Gajeong-ro, Yuseong-gu, Daejeon 305-333 (Korea, Republic of)

2014-10-15

Graphical abstract: The highly flexible and conductive graphene layer can enhance electron transfer, protect metal oxides against disintegration and aggregation and buffer the strain induced by volume expansion during cycles. The mesoporous surface layer provides an open network for Li+ diffusion. - Highlights: • Novel cocktail effects of 2D mesoporous WO{sub 3−X}/graphene for lithium ion battery. • New approach for lithium ion battery by easy and unique synthesis method. • Mechanism study with proper data for understanding a reaction on anode surface. - Abstract: A novel mesoporous WO{sub 3−X}/graphene composite was developed. This material allowed rapid electron and Li{sup +} ion diffusion when used as a Li-ion battery (LIB) anode material. Remarkably, the graphene support protected WO{sub 3−X} from changing volume during the electrochemical cycling process; this process generally induces capacity loss. The current work describes a high-performance anode material for LIB that has highly dense WO{sub 3−X}, as well as high capacity, rate capability and stability.

Improving the Tribological Properties of Spark-Anodized Titanium by Magnetron Sputtered Diamond-Like Carbon

Directory of Open Access Journals (Sweden)

Zhaoxiang Chen

2018-02-01

Full Text Available Spark-anodization of titanium can produce adherent and wear-resistant TiO2 film on the surface, but the spark-anodized titanium has lots of surface micro-pores, resulting in an unstable and high friction coefficient against many counterparts. In this study, the diamond-like carbon (DLC was introduced into the micro-pores of spark-anodized titanium by the magnetron sputtering technique and a TiO2/DLC composite coating was fabricated. The microstructure and tribological properties of TiO2/DLC composite coating were investigated and compared with the anodic TiO2 mono-film and DLC mono-film. Results show that the DLC deposition significantly decreased the surface roughness and porosity of spark-anodized titanium. The fabricated TiO2/DLC composite coating exhibited a more stable and much lower friction coefficient than anodic TiO2 mono-film. Although the friction coefficient of the composite coating and the DLC mono-film was similar under both light load and heavy load conditions, the wear life of the composite coating was about 43% longer than that of DLC mono-film under heavy load condition. The wear rate of titanium with protective composite coating was much lower than that of titanium with DLC mono-film. The superior low friction coefficient and wear rate of the TiO2/DLC composite coating make it a good candidate as protective coating on titanium alloys.

Advanced structures in electrodeposited tin base anodes for lithium ion batteries

International Nuclear Information System (INIS)

Zhao Haipeng; Jiang Changyin; He Xiangming; Ren Jianguo; Wan Chunrong

2007-01-01

A novel composite anode material consisted of electrodeposited Sn dispersing in a conductive micro-porous carbon membrane, which was directly coated on Cu current collector, was investigated. The composite material was prepared by: (1) casting a polyacrylonitrile (PAN)/dimethylformamide (DMF) solution that contained silica particles on a copper foil, (2) removing the solvent by evaporation, (3) dissolving the silica particles by immersing the copper foil into an alkaline solution, (4) drying the copper foil coated by micro-porous membrane, (5) electrodepositing Sn onto the copper foil through the micro-pores in the micro-porous membrane, and (6) annealing as-obtained composite material. This method provided the composite material with high decentralization of Sn and supporting medium purpose of conductive carbon membrane deriving from pyrolysis of PAN. SEM, XRD and EDS analysis confirmed this structure. The characteristic structure was beneficial to inhibit the aggregation between Sn micro-particles, to relax the volume expansion during cycling, and to improve the cycleability of electrode. Galvanostatic tests indicated the discharge capacity of the composite material remained over 550 mAh g -1 and 71.4% of charge retention after 30 cycles, while that of the electrode prepared by electrodepositing Sn on a bare Cu foil decreased seriously to 82.5 mAh g -1 and 13%. These results show that the composite material is a promising anode material with larger specific capacity and long cycle life for lithium ion batteries

PEO of pre-anodized Al-Si alloys: Corrosion properties and influence of sealings

Science.gov (United States)

Mohedano, M.; Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A.

2015-08-01

Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al2O3, γ-Al2O3 and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

Nanostructured palladium-La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3}/Y{sub 2}O{sub 3}-ZrO{sub 2} composite anodes for direct methane and ethanol solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Jiang, San Ping; Ye, Yinmei; He, Tianmin; Ho, See Boon [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2008-10-15

A palladium-impregnated La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}}/yttria-stabilized zirconia (LSCM/YSZ) composite anode is investigated for the direct utilization of methane and ethanol fuels in solid oxide fuel cells (SOFCs). Impregnation of Pd nanoparticles significantly enhances the electrocatalytic activity of LSCM/YSZ composite anodes for the methane and ethanol electrooxidation reaction. At 800 C, the maximum power density is increased by two and eight times with methane and ethanol fuels, respectively, for a cell with the Pd-impregnated LSCM/YSZ composite anode, as compared with that using a pure LSCM/YSZ anode. No carbon deposition is observed during the reaction of methane and ethanol fuels on the Pd-impregnated LSCM/YSZ composite anode. The results show the promises of nanostructured Pd-impregnated LSCM/YSZ composites as effective anodes for direct methane and ethanol SOFCs. (author)

Active and inactive buffering effect on the electrochemical behavior of Sn–Ni/MWCNT composite anodes prepared by pulse electrodeposition for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Uysal, Mehmet, E-mail: mehmet_uys@yahoo.com; Cetinkaya, Tugrul; Alp, Ahmet; Akbulut, Hatem

2015-10-05

Highlights: • Sn–Ni/MWCNT anodes were produced by pulse electrodeposition. • The effect of MWCNT studied on electrochemical properties of composite electrodes. • A high reversible capacity, and good cyclability were achieved for Sn–Ni/MWCNT (10 g L{sup −1}). - Abstract: Cycling stability of pure tin electrodes was aimed to improve by using suitable combination of nickel and multiwalled carbon nanotubes (MWCNTs). Nanocrystalline Sn–Ni/MWCNT composite was prepared by ultrasonic-pulse electrodeposition on a copper substrate in a pyrophosphate bath containing different concentrations of multi-walled carbon nanotubes. Surface morphology of produced Sn–Ni/MWCNT composites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) was conducted to understand the elemental surface composition of composites. X-ray diffraction analysis was carried out to investigate structure of Sn–Ni/MWCNT composites. The electrochemical performances of Sn–Ni/MWCNT composite electrodes have been investigated by charge/discharge tests, cyclic voltammetric experiments and the ac impedance technique. These cells discharge capacity cyclically tested by a battery tester at a constant current in voltage range between 0.02 V and 1.5 V. The concentrations of MWCNTs were shown to be a crucial factor to improve Sn–Ni/MWCNT composite anodes for cyclability and reversible capacity.

Facile synthesis of one-dimensional hollow Sb2O3@TiO2 composites as anode materials for lithium ion batteries

Science.gov (United States)

Wang, Zhaomin; Cheng, Yong; Li, Qian; Chang, Limin; Wang, Limin

2018-06-01

Metallic Sb is deemed as a promising anode material for lithium ion batteries (LIBs) due to its flat voltage platform and high security. Nevertheless, the limited capacity restricts its large-scale application. Therefore, a simple and effective method to explore novel antimony trioxide with high capacity used as anode material for LIBs is imperative. In this work, we report a facile and efficient strategy to fabricate 1D hollow Sb2O3@TiO2 composites by using the Kirkendall effect. When used as an anode material for LIBs, the optimal Sb2O3@TiO2 composite displays a high reversible discharge capacity of 593 mAh g-1 at a current density of 100 mA g-1 after 100 cycles and a relatively superior discharge capacity of 439 mAh g-1 at a current density of 500 mA g-1 even after 600 cycles. In addition, a reversible discharge capacity of 334 mAh g-1 can also be obtained even at a current density of 2000 mA g-1. The excellent cycling stability and rate performance of the Sb2O3@TiO2 composite can be attributed to the synergistic effect of TiO2 shell and hollow structure of Sb2O3, both of which can effectively buffer the volume expansion and maintain the integrity of the electrode during the repeated charge-discharge cycles.

Nano-composite of PtRu alloy electrocatalyst and electronically conducting polymer for use as the anode in a direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Jongho Choi; Kyungwon Park; Hyekyung Lee; Youngmin Kim; Jaesuk Lee; Yungeun Sung [Kwangju Inst. of Science and Technology, Dept. of Materials Science and Engineering, Gwangju (Korea)

2003-08-15

Nano-composites comprised of PtRu alloy nanoparticles and an electronically conducting polymer for the anode electrode in direct methanol fuel cell (DMFC) were prepared. Two conducting polymers of poly(N-vinyl carbazole) and poly(9-(4-vinyl-phenyl)carbazole) were used for the nano-composite electrodes. Structural analyses were carried out using Fourier transform nuclear magnetic resonance spectroscopy, AC impedance spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Electrocatalytic activities were investigated by voltammetry and chronoamperometry in a 2 M CH{sub 3}OH/{sub 0.5} M H{sub 2}SO{sub 4} solution and the data compared with a carbon-supported PtRu electrode. XRD patterns indicated good alloy formation and nano-composite formation was confirmed by TEM. Electrochemical measurements and DMFC unit-cell tests indicate that the nano-composites could be useful in a DMFC, but its performance would be slightly lower than that of a carbon-supported electrode. The interfacial property between the PtRu-polymer nano-composite anode and the polymer electrolyte was good, as evidenced by scanning electron microscopy. For better performance in a DMFC, a higher electric conductivity of the polymer and a lower catalyst loss are needed in nano-composite electrodes. (Author)

Assembly of core–shell structured porous carbon–graphene composites as anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Guo, Rong; Zhao, Li; Yue, Wenbo

2015-01-01

As potential anode materials for lithium-ion batteries, mesoporous carbons such as CMK-3 and CMK-8 usually show stable cycling performances but only slightly higher reversible capacities than commercial graphite. Graphene has much higher theoretical capacity than that of graphite in theory. However, its electrochemical behavior is not as good as expected due to the aggregation of graphene nanosheets. Herein we describe a novel strategy for the preparation of core–shell structured porous carbon–graphene composites. Compared to pure porous carbons or pure graphene nanosheets, these novel composites exhibit superior electrochemical performances including higher reversible capacities and better cycle/rate performances. This core–shell structure can avoid the aggregation of graphene nanosheets as well as may stabilize the mesostructure of porous carbon, which is beneficial to improving the electrochemical performances of the composites

Preparation of titanium dioxide films on etched aluminum foil by vacuum infiltration and anodizing

Science.gov (United States)

Xiang, Lian; Park, Sang-Shik

2016-12-01

Al2O3-TiO2 (Al-Ti) composite oxide films are a promising dielectric material for future use in capacitors. In this study, TiO2 films were prepared on etched Al foils by vacuum infiltration. TiO2 films prepared using a sol-gel process were annealed at various temperatures (450, 500, and 550 °C) for different time durations (10, 30, and 60 min) for 4 cycles, and then anodized at 100 V. The specimens were characterized using X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy. The results show that the tunnels of the specimens feature a multi-layer structure consisting of an Al2O3 outer layer, an Al-Ti composite oxide middle layer, and an aluminum hydrate inner layer. The electrical properties of the specimens, such as the withstanding voltage and specific capacitance, were also measured. Compared to specimens without TiO2 coating, the specific capacitances of the TiO2-coated specimens are increased. The specific capacitance of the anode Al foil with TiO2 coating increased by 42% compared to that of a specimen without TiO2 coating when annealed at 550 °C for 10 min. These composite oxide films could enhance the specific capacitance of anode Al foils used in dielectric materials.

One-Pot Synthesis of CoSex -rGO Composite Powders by Spray Pyrolysis and Their Application as Anode Material for Sodium-Ion Batteries.

Science.gov (United States)

Park, Gi Dae; Kang, Yun Chan

2016-03-14

A simple one-pot synthesis of metal selenide/reduced graphene oxide (rGO) composite powders for application as anode materials in sodium-ion batteries was developed. The detailed mechanism of formation of the CoSe(x)-rGO composite powders that were selected as the first target material in the spray pyrolysis process was studied. The crumple-structured CoSe(x)-rGO composite powders prepared by spray pyrolysis at 800 °C had a crystal structure consisting mainly of Co0.85 Se with a minor phase of CoSe2. The bare CoSe(x) powders prepared for comparison had a spherical shape and hollow structure. The discharge capacities of the CoSe(x)-rGO composite and bare CoSe(x) powders in the 50th cycle at a constant current density of 0.3 A g(-1) were 420 and 215 mA h g(-1), respectively, and their capacity retentions measured from the second cycle were 80 and 46%, respectively. The high structural stability of the CoSe(x)-rGO composite powders for repeated sodium-ion charge and discharge processes resulted in superior sodium-ion storage properties compared to those of the bare CoSe(x) powders. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

International Nuclear Information System (INIS)

Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

2014-01-01

Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm 2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

SnTe-TiC-C composites as high-performance anodes for Li-ion batteries

Science.gov (United States)

Son, Seung Yeon; Hur, Jaehyun; Kim, Kwang Ho; Son, Hyung Bin; Lee, Seung Geol; Kim, Il Tae

2017-10-01

Intermetallic SnTe composites dispersed in a conductive TiC/C hybrid matrix are synthesized by high-energy ball milling (HEBM). The electrochemical performances of the composites as potential anodes for Li-ion batteries are evaluated. The structural and morphological characteristics of the SnTe-TiC-C composites with various TiC contents are investigated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy, which reveal that SnTe and TiC are uniformly dispersed in a carbon matrix. The electrochemical performance is significantly improved by introducing TiC to the SnTe-C composite; higher TiC contents result in better performances. Among the prepared composites, the SnTe-TiC (30%)-C and SnTe-TiC (40%)-C electrodes exhibit the best electrochemical performance, showing the reversible capacities of, respectively, 652 mAh cm-3 and 588 mAh cm-3 after 400 cycles and high rate capabilities with the capacity retentions of 75.4% for SnTe-TiC (30%)-C and 82.2% for SnTe-TiC (40%)-C at 10 A g-1. Furthermore, the Li storage reaction mechanisms of Te or Sn in the SnTe-TiC-C electrodes are confirmed by ex situ XRD.

Carbon-covered Fe_3O_4 hollow cubic hierarchical porous composite as the anode material for lithium-ion batteries

International Nuclear Information System (INIS)

Chen, Shouhui; Zhou, Rihui; Chen, Yaqin; Fu, Yuanyuan; Li, Ping; Song, Yonghai; Wang, Li

2017-01-01

In this work, Prussian blue nanocrystals, a kind of cubic metal-organic frameworks, was firstly covered by a uniform layer of resorcinol-formaldehyde (RF) resin, and then followed with heat treatment at different pyrolysis temperatures. The effects of pyrolysis temperature on the morphologies, phase, pore size, and electrochemical performance of the pyrolysis products were studied in this work. The composite generated at 600 "∘C, FexC600, was a hollow cubic composite of Fe_3O_4 covered by a thin RF-derived carbon layer. The carbon layer on FexC600 was a robust and conductive protective layer, which can accommodate Fe_3O_4 NPs and withstand the huge volume change of Fe_3O_4 during the process of discharge and charge. When used as anodes for lithium-ion batteries, FexC600 showed excellent electrochemical performance. It delivered a discharge capacity of 1126 mAh g"−"1 with a coulombic efficiency of 98.8% at the current density of 100 mA g"−"1 after 100 times discharge/charge cycling. It even delivered a capacity of 492 mAh g"−"1 at the current density of 500 mA g"−"1. This cubic hollow composite would be a promising alternative anode material for lithium-ion batteries.

Fabrication of porous anodic alumina using normal anodization and pulse anodization

Science.gov (United States)

Chin, I. K.; Yam, F. K.; Hassan, Z.

2015-05-01

This article reports on the fabrication of porous anodic alumina (PAA) by two-step anodizing the low purity commercial aluminum sheets at room temperature. Different variations of the second-step anodization were conducted: normal anodization (NA) with direct current potential difference; pulse anodization (PA) alternate between potential differences of 10 V and 0 V; hybrid pulse anodization (HPA) alternate between potential differences of 10 V and -2 V. The method influenced the film homogeneity of the PAA and the most homogeneous structure was obtained via PA. The morphological properties are further elucidated using measured current-transient profiles. The absent of current rise profile in PA indicates the anodization temperature and dissolution of the PAA structure were greatly reduced by alternating potential differences.

Improved Anode for a Direct Methanol Fuel Cell

Science.gov (United States)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the

A highly stable (SnOx-Sn)@few layered graphene composite anode of sodium-ion batteries synthesized by oxygen plasma assisted milling

Science.gov (United States)

Cheng, Deliang; Liu, Jiangwen; Li, Xiang; Hu, Renzong; Zeng, Meiqing; Yang, Lichun; Zhu, Min

2017-05-01

The (SnOx-Sn)@few layered graphene ((SnOx-Sn)@FLG) composite has been synthesized by oxygen plasma-assisted milling. Owing to the synergistic effect of rapid plasma heating and ball mill grinding, SnOx (1 ≤ x ≤ 2) nanoparticles generated from the reaction of Sn with oxygen are tightly wrapped by FLG nanosheets which are simultaneously exfoliated from expanded graphite, forming secondary micro granules. Inside the granules, the small size of the SnOx nanoparticles enables the fast kinetics for Na+ transfer. The in-situ formed FLG and residual Sn nanoparticles improve the electrical conductivity of the composite, meanwhile alleviate the aggregation of SnOx nanoparticles and relieve the volume change during the cycling, which is beneficial for the cyclic stability for the Na+ storage. As an anode material for sodium-ion batteries, the (SnOx-Sn)@FLG composite exhibits a high reversible capacity of 448 mAh g-1 at a current density of 100 mA g-1 in the first cycle, with 82.6% capacity retention after 250 cycles. Even when the current density increases to 1000 mA g-1, this composite retains 316.5 mAh g-1 after 250 cycles. With superior Na+ storage stability, the (SnOx-Sn)@FLG composite can be a promising anode material for high performance sodium-ion batteries.

Synthesis and characterisation of Co-Co(OH)2 composite anode material on Cu current collector for energy storage devices

Science.gov (United States)

Yavuz, Abdulcabbar; Yakup Hacıibrahimoğlu, M.; Bedir, Metin

2017-04-01

A Co-Co(OH)2 modified electrode on inexpensive Cu substrate was synthesized at room temperature and demonstrated to be a promising anode material for energy storage devices. A modified Co film was obtained potentiostatically and was then potentiodynamically treated with KOH solution to form Co(OH)2. Co-Co(OH)2 coatings were obtained and were dominated by Co(OH)2 at the oxidized side, whereas Co dominant Co-Co(OH)2 occurred at the reduced side (-1.1 V). As OH- ions were able to diffuse into (out of) the film during oxidation (reduction) and did not react with the Cu current collector, the Co-Co(OH)2 electrode can be used as an anode material in energy storage devices. Although the specific capacitance of the electrodes varied depending on thickness, the redox reaction between the modified electrode and KOH electrolyte remained the same consisting of a surface-controlled and diffusion-controlled mechanism which had a desirable fast charge and discharge property. Capacity values remained constant after 250 cycles as the film evolved. Overall capacity retention was 84% for the film after 450 scans. A specific capacitance of 549 F g-1 was obtained for the Co-Co(OH)2 composite electrode in 6 M KOH at a scan rate of 5 mV s-1 and 73% of capacitance was retained when the scan rate was increased to 100 mV s-1.

Ternary CNTs@TiO₂/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries.

Science.gov (United States)

Madian, Mahmoud; Ummethala, Raghunandan; Naga, Ahmed Osama Abo El; Ismail, Nahla; Rümmeli, Mark Hermann; Eychmüller, Alexander; Giebeler, Lars

2017-06-20

TiO₂ nanotubes (NTs) synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li⁺ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs)@TiO₂/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO₂/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO₂ and TiO₂/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li⁺ ion diffusivity, promoting a strongly favored lithium insertion into the TiO₂/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability.

Cu-SnO2 nanostructures obtained via galvanic replacement control as high performance anodes for lithium-ion storage

Science.gov (United States)

Nguyen, Tuan Loi; Park, Duckshin; Hur, Jaehyun; Son, Hyung Bin; Park, Min Sang; Lee, Seung Geol; Kim, Ji Hyeon; Kim, Il Tae

2018-01-01

SnO2 has been considered as a promising anode material for lithium ion batteries (LIBs) because of its high theoretical capacity (782 mAh g-1). However, the reaction between lithium ions and Sn causes a large volume change, resulting in the pulverization of the anode, a loss of contact with the current collector, and a deterioration in electrochemical performance. Several strategies have been proposed to mitigate the drastic volume changes to extend the cyclic life of SnO2 materials. Herein, novel composites consisting of Cu and SnO2 were developed via the galvanic replacement reaction. The reaction was carried out at 180 °C for different durations and triethylene glycol was used as the medium solvent. The structure, morphology, and composition of the composites were analyzed by X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy. The reaction time affected the particle size, which in turn affected the reaction kinetics. Furthermore, the novel nanostructures contained an inactive metal phase (Cu), which acted both as the buffer space against the volume change of Sn during the alloying reaction and as the electron conductor, resulting in a lower impedance of the composites. When evaluated as potential anodes for LIBs, the composite electrodes displayed extraordinary electrochemical performance with a high capacity and Coulombic efficiency, an excellent cycling stability, and a superior rate capability compared to a Sn electrode.

Metal-based anode for high performance bioelectrochemical systems through photo-electrochemical interaction

Science.gov (United States)

Liang, Yuxiang; Feng, Huajun; Shen, Dongsheng; Long, Yuyang; Li, Na; Zhou, Yuyang; Ying, Xianbin; Gu, Yuan; Wang, Yanfeng

2016-08-01

This paper introduces a novel composite anode that uses light to enhance current generation and accelerate biofilm formation in bioelectrochemical systems. The composite anode is composed of 316L stainless steel substrate and a nanostructured α-Fe2O3 photocatalyst (PSS). The electrode properties, current generation, and biofilm properties of the anode are investigated. In terms of photocurrent, the optimal deposition and heat-treatment times are found to be 30 min and 2 min, respectively, which result in a maximum photocurrent of 0.6 A m-2. The start-up time of the PSS is 1.2 days and the maximum current density is 2.8 A m-2, twice and 25 times that of unmodified anode, respectively. The current density of the PSS remains stable during 20 days of illumination. Confocal laser scanning microscope images show that the PSS could benefit biofilm formation, while electrochemical impedance spectroscopy indicates that the PSS reduce the charge-transfer resistance of the anode. Our findings show that photo-electrochemical interaction is a promising way to enhance the biocompatibility of metal anodes for bioelectrochemical systems.

Anodizing And Sealing Aluminum In Nonchromated Solutions

Science.gov (United States)

Emmons, John R.; Kallenborn, Kelli J.

1995-01-01

Improved process for anodizing and sealing aluminum involves use of 5 volume percent sulfuric acid in water as anodizing solution, and 1.5 to 2.0 volume percent nickel acetate in water as sealing solution. Replaces process in which sulfuric acid used at concentrations of 10 to 20 percent. Improved process yields thinner coats offering resistance to corrosion, fatigue life, and alloy-to-alloy consistency equal to or superior to those of anodized coats produced with chromated solutions.

Designing Si/porous-C composite with buffering voids as high capacity anode for lithium-ion batteries

International Nuclear Information System (INIS)

Yue, Lu; Zhang, Wenhui; Yang, Jingfeng; Zhang, Lingzhi

2014-01-01

A novel Si/porous-C composite with buffering voids was prepared by the co-assembly of phenol-formaldehyde resin, SiO 2 and Si nanoparticles, followed by a carbonizing process and subsequent removal of SiO 2 template. Si nanoparticle was coated with a layer of porous carbon shell with rationally designed void in between which provides the accommodating space for the volume change of Si over cycling. The as-prepared composite electrode exhibited good electrochemical performances as an anode material in lithium-ion cells, showing a stable reversible capacity of 980 mAh g −1 over 80 cycles with small capacity fade of 0.17%/cycle and high rate capability (721 mAh g −1 at 2000 mA g −1 )

Coaxial silicon/multi-walled carbon nanotube nanocomposite anodes for long cycle life lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Tocoglu, Ubeyd, E-mail: utocoglu@sakarya.edu.tr; Cevher, Ozgur; Guler, M. Oguz; Akbulut, Hatem

2014-06-01

Abstract: In this work silicon/multi walled carbon nanotube (MWCNT) composite anodes were produced via direct current (DC) magnetron sputtering of silicon onto carbon nanotube papers (buckypapers). The amount of silicon in the composite anodes was varied by using different sputtering powers of 150 W, 175 W, 200 W and the effect on the cell performance was studied. Phase analysis was conducted with X-ray diffraction (XRD) technique and Raman spectroscopy. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses were employed for morphological characterization of anodes. Energy dispersive spectroscopy (EDS) mapping was used to observe silicon distribution on the buckypapers. Cyclic voltammetry (CV) tests were carried out to reveal reversible reactions between silicon and lithium. Galvanostatic charge/discharge technique was employed to determine the cyclic performance of anodes. Electrochemical impedance spectroscopy technique was used to understand the relation between cyclic performance and internal resistance of cells. The results showed capacity retention of silicon anodes was improved with composite structure and higher capacity values were achieved than graphite anodes. The silicon/carbon nanotube composite produced with 150 W showed the best cycle stability after 100 cycles of galvanostatic charge/discharge tests with capacity value of 620 mAh g{sup −1}.

Intergrown SnO{sub 2}–TiO{sub 2}@graphene ternary composite as high-performance lithium-ion battery anodes

Energy Technology Data Exchange (ETDEWEB)

Jiao, Zheng; Gao, Renmei [Shanghai University, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering (China); Tao, Haihua [Inspection Center of Industrial Products and Raw Materials of SHCIQ (China); Yuan, Shuai [Shanghai University, Research Center of Nanoscience and Nanotechnology (China); Xu, Laiqiang; Xia, Saisai; Zhang, Haijiao, E-mail: hjzhang128@shu.edu.cn [Shanghai University, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering (China)

2016-10-15

In recent years, a lot of metal oxides with high theoretical capacity have widely investigated as the high-performance anode materials for lithium-ion batteries (LIBs). In this work, a simple, facile and effective one-pot hydrothermal strategy toward ternary SnO{sub 2}–TiO{sub 2}@graphene composite has been developed by using SnCl{sub 2} and TiOSO{sub 4} as the starting materials. The obtained composite demonstrates a unique structure and high surface areas, in which both SnO{sub 2} and TiO{sub 2} nanoparticles are well grown on the surface of graphene. More interestingly, the SnO{sub 2} and TiO{sub 2} nanoparticles are intergrowth together, totally different with the traditional ternary hybrids. When used as anode material for LIBs, the introduction of TiO{sub 2} plays a crucial role in maintaining the structural stability of the electrode during Li{sup +} insertion/extraction, which can effectively prevent the aggregation of SnO{sub 2} nanoparticles. The electrochemical tests indicate that as-prepared SnO{sub 2}–TiO{sub 2}@graphene composite exhibits a high capacity of 1276 mA h g{sup −1} after 200 cycles at the current density of 200 mA g{sup −1}. Furthermore, the composite also maintains the specific capacity of 611 mA h g{sup −1} at an ultrahigh current density of 2000 mA g{sup −1}, which is superior to those of the reported SnO{sub 2} and SnO{sub 2}/graphene hybrids. Accordingly, the remarkable electrochemical performance of ternary SnO{sub 2}–TiO{sub 2}@graphene composites is mainly attributed to their unique nanostructure, high surface areas, and the synergistic effect not only between graphene and metal oxides but also between the intergrown SnO{sub 2} and TiO{sub 2} nanoparticles.Graphical abstractIntergrown SnO{sub 2} and TiO{sub 2} nanoparticles have been successfully anchored onto the graphene nanosheets as high-performance lithium-ion battery anodes.

Preparation and electrochemical properties of nanocable-like Nb2O5/surface-modified carbon nanotubes composites for anode materials in lithium ion batteries

International Nuclear Information System (INIS)

Shi, Chongfu; Xiang, Kaixiong; Zhu, Yirong; Chen, Xianhong; Zhou, Wei; Chen, Han

2017-01-01

Highlights: •The acid pretreatment for CNTs is a key factor to fabricate nanocable-like Nb 2 O 5 /SMCNTs composites. •The polar functional groups can induce the symmetrical growth of Nb 2 O 5 nanoparticitles on the surface of SMCNTs. •SMCNTs can provide sufficient conductive contacts for composites and abundant active sites for electrochemical reaction. -- Abstract: Uniform nanocable-like Nb 2 O 5 /surface-modified carbon nanotubes (SMCNTs) composites for anode materials in lithium ion batteries were synthesized by hydrothermal method. It was indicated that Nb 2 O 5 nanoparticles were tightly and uniformly cultivated on carbon nanotubes when CNTs were pretreated with concentrated H 2 SO 4 . As a result, Nb 2 O 5 /SMCNTs composite materials showed remarkable electrochemical performance as anode materials for lithium-ion batteries. It delivered a high reversible capacity of 441 mA h g −1 cycled at the current density of 40 mA g −1 after 100 cycles and an excellent rate capacity of 185 mA h g −1 at the high current density of 5000 mA g −1 after 200 cycles.

Graphene–sponges as high-performance low-cost anodes for microbial fuel cells

KAUST Repository

Xie, Xing; Yu, Guihua; Liu, Nian; Bao, Zhenan; Criddle, Craig S.; Cui, Yi

2012-01-01

A high-performance microbial fuel cell (MFC) anode was constructed from inexpensive materials. Key components were a graphene-sponge (G-S) composite and a stainless-steel (SS) current collector. Anode fabrication is simple, scalable

Fabrication of flower-like tin/carbon composite microspheres as long-lasting anode materials for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Kang, Tae-Woo [Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Lim, Hyung-Seok [Department of WCU Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Park, Seong-Jin [Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Sun, Yang-Kook [Department of WCU Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of); Suh, Kyung-Do, E-mail: kdsuh@hanyang.ac.kr [Department of Chemical Engineering, College of Engineering, Hanyang University, Seoul, 133-791 (Korea, Republic of)

2017-01-01

In this work, we report the fabrication of the flower-like tin/carbon (Sn/C) composite microspheres using sulfonated semi-interpenetrating polystyrene (SPS) microspheres as a carbon precursor. The sulfonation degree of SPS has great effects on the resulting particle size, morphology, amount of introduced Sn, and the carbonization yield of the microspheres after heat treatment. The obtained Sn/C composite microspheres were characterized by scanning electron microscopy (SEM), focused-ion beam SEM, and X-ray diffraction. The flower-like Sn/C composite electrodes exhibited higher charge-discharge capacities than those of graphite as an anode material for a lithium ion battery. In addition, they show a long lasting cyclability, even through 400 cycles. - Highlights: • Tin nanocrystals are introduced in flower-like carbon spheres with many ripples. • Long lasting cyclability is exhibited at 1 C rate up to 400 cycles. • Tin content of composite spheres depends on chemical treatment of polymer microspheres.

FIB-SEM investigation of trapped intermetallic particles in anodic oxide films on AA1050 aluminium

DEFF Research Database (Denmark)

Jariyaboon, Manthana; Møller, Per; Dunin-Borkowski, Rafal E.

2011-01-01

-containing intermetallic particles incorporated into the anodic oxide films on industrially pure aluminium (AA1050, 99.5 per cent) has been investigated. AA1050 aluminium was anodized in a 100?ml/l sulphuric acid bath with an applied voltage of 14?V at 20°C ±2°C for 10 or 120?min. The anodic film subsequently was analyzed......Purpose - The purpose of this investigation is to understand the structure of trapped intermetallics particles and localized composition changes in the anodized anodic oxide film on AA1050 aluminium substrates. Design/methodology/approach - The morphology and composition of Fe......-shaped particles were embedded in the anodic oxide film as a thin strip structure and located near the top surface of the film, whereas the round-shaped particles were trapped in the film with a spherical structure, but partially dissolved and were located throughout the thickness of the anodic film. The Fe...

The design of a Li-ion full cell battery using a nano silicon and nano multi-layer graphene composite anode

Science.gov (United States)

Eom, KwangSup; Joshi, Tapesh; Bordes, Arnaud; Do, Inhwan; Fuller, Thomas F.

2014-03-01

In this study, a Si-graphene composite, which is composed of nano Si particles and nano-sized multi-layer graphene particles, and micro-sized multi-layer graphene plate conductor, was used as the anode for Li-ion battery. The Si-graphene electrode showed the high capacity and stable cyclability at charge/discharge rate of C/2 in half cell tests. Nickel cobalt aluminum material (NCA) was used as a cathode in the full cell to evaluate the practicality of the new Si-graphene material. Although the Si-graphene anode has more capacity than the NCA cathode in this designed full cell, the Si-graphene anode had a greater effect on the full-cell performance due to its large initial irreversible capacity loss and continuous SEI formation during cycling. When fluoro-ethylene carbonate was added to the electrolyte, the cyclability of the full cell was much improved due to less SEI formation, which was confirmed by the decreases in the 1st irreversible capacity loss, overpotential for the 1st lithiation, and the resistance of the SEI.

Anodic Materials for Lithium-ion Batteries: TiO2-rGO Composites for High Power Applications

International Nuclear Information System (INIS)

Minella, M.; Versaci, D.; Casino, S.; Di Lupo, F.; Minero, C.; Battiato, A.; Penazzi, N.; Bodoardo, S.

2017-01-01

Titanium dioxide/reduced graphene oxide (TiO 2 -rGO) composites were synthesized at different loadings of carbonaceous phase, characterized and used as anode materials in Lithium-ion cells, focusing not only on the high rate capability but also on the simplicity and low cost of the electrode production. It was therefore chosen to use commercial TiO 2 , GO was synthesized from graphite, adsorbed onto TiO 2 and reduced to rGO following a chemical, a photocatalytic and an in situ photocatalytic procedure. The synthesized materials were in-depth characterized with a multi-technique approach and the electrochemical performances were correlated i) to an effective reduction of the GO oxidized moieties and ii) to the maintenance of the 2D geometry of the final graphenic structure observed. TiO 2 -rGO obtained with the first two procedures showed good cycle stability, high capacity and impressive rate capability particularly at 10% GO loading. The photocatalytic reduction applied in situ on preassembled electrodes showed similarly good results reaching the goal of a further simplification of the anode production.

Ternary CNTs@TiO2/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries

Science.gov (United States)

Madian, Mahmoud; Ummethala, Raghunandan; Abo El Naga, Ahmed Osama; Ismail, Nahla; Rümmeli, Mark Hermann; Eychmüller, Alexander; Giebeler, Lars

2017-01-01

TiO2 nanotubes (NTs) synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li+ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs)@TiO2/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO2/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO2 and TiO2/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li+ ion diffusivity, promoting a strongly favored lithium insertion into the TiO2/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability. PMID:28773032

Ternary CNTs@TiO2/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Mahmoud Madian

2017-06-01

Full Text Available TiO2 nanotubes (NTs synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li+ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs@TiO2/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO2/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO2 and TiO2/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li+ ion diffusivity, promoting a strongly favored lithium insertion into the TiO2/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability.

Facile fabrication of composited Mn_3O_4/Fe_3O_4 nanoflowers with high electrochemical performance as anode material for lithium ion batteries

International Nuclear Information System (INIS)

Zhao, Dianyun; Hao, Qin; Xu, Caixia

2015-01-01

Graphical abstract: Mn_3O_4/Fe_3O_4 nanoflowers are successfully prepared through one step dealloying of Mn_5Fe_5Al_9_0 alloy at room temperature. This hierarchical flower-like structure with consists of a packed array of uniform regular hexagon-like nanoslices. Combined with the specific hierarchical flower-like architecture and the synergistic effect exerted by Mn_3O_4 and Fe_3O_4, the nanocomposite exhibits enhanced performance as anode material for lithium ion batteries than pure Mn_3O_4 and Fe_3O_4 anode. - Highlights: • Mn_3O_4/Fe_3O_4 nanoflowers are easily prepared by one step dealloying method. • The nanoflowers consist of packed regular nanoslices with interconnected voids. • Mn_3O_4/Fe_3O_4 nanoflowers deliver higher discharge capacity than Mn_3O_4 and Fe_3O_4. • Mn_3O_4/Fe_3O_4 nanoflowers show lower initial irreversible loss than Mn_3O_4 anode. - Abstract: Mn_3O_4/Fe_3O_4 nanoflowers with controllable components are simply fabricated through one step etching of the Mn_5Fe_5Al_9_0 ternary alloy. The as-made hierarchical flower-like structure with interconnected voids consists of a packed array of uniform regular hexagon-like nanoslices. Based on the simple dealloying strategy the target metals are directly converted to uniform nanocomposite composed of Mn_3O_4 and Fe_3O_4 species. With the unique hierarchical flower-like structure and the synergistic effects between Mn_3O_4 and Fe_3O_4, the nanocomposite exhibits higher performance as anode material for lithium ion batteries than that of pure Mn_3O_4 and Fe_3O_4 anodes. The Mn_3O_4/Fe_3O_4 nanocomposite deliver much higher discharge capacity and lower initial irreversible loss than Mn_3O_4 anode. The Mn_3O_4/Fe_3O_4 anode material also shows an excellent cycling stability at the high rate of 1500 mA g"−"1 with outstanding rate capability. With the advantages of simple preparation and excellent electrochemical performance, Mn_3O_4/Fe_3O_4 nanoflowers manifest great application potential as

Effects of half-wave and full-wave power source on the anodic oxidation process on AZ91D magnesium alloy

Science.gov (United States)

Wang, Ximei; Zhu, Liqun; Li, Weiping; Liu, Huicong; Li, Yihong

2009-03-01

Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na 2SiO 3 with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg 2SiO 4 and amorphous SiO 2.

Effects of half-wave and full-wave power source on the anodic oxidation process on AZ91D magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Wang Ximei [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)], E-mail: wangximei126@126.com; Zhu Liqun; Li Weiping; Liu Huicong; Li Yihong [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)

2009-03-15

Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na{sub 2}SiO{sub 3} with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg{sub 2}SiO{sub 4} and amorphous SiO{sub 2}.

Characteristics from Recycled of Zinc Anode used as a Corrosion Preventing Material on Board Ship

Science.gov (United States)

Barokah, B.; Semin, S.; Kaligis, D. D.; Huwae, J.; Fanani, M. Z.; Rompas, P. T. D.

2018-02-01

The objective of this research is to obtain the values of chemical composition, electrochemical potential and electrochemical efficiency. Methods used were experiment with physical tests conducted in metallurgical laboratory and DNV-RP-B401 cathode protection design DNV (Det Norske Veritas) standard. The results showed that the composition of chemical as Zinc (Zn), Aluminium, Cadmium, Plumbumb, Copper and Indium is suitable of standard. The values of electrochemical potential and electrochemical efficiency were respectively. However it can be concluded that the normal meaning of recycled zinc anode with increasing melting temperature can produce zinc anode better than original zinc anode and can be used as cathode protection on board ships. This research can assist in the management of used zinc anode waste, the supply of zinc anodes for consumers at relatively low prices, and recommendations of using zinc anodes for the prevention of corrosion on board ship.

Binder-free graphene and manganese oxide coated carbon felt anode for high-performance microbial fuel cell.

Science.gov (United States)

Zhang, Changyong; Liang, Peng; Yang, Xufei; Jiang, Yong; Bian, Yanhong; Chen, Chengmeng; Zhang, Xiaoyuan; Huang, Xia

2016-07-15

A novel anode was developed by coating reduced graphene oxide (rGO) and manganese oxide (MnO2) composite on the carbon felt (CF) surface. With a large surface area and excellent electrical conductivity, this binder-free anode was found to effectively enhance the enrichment and growth of electrochemically active bacteria and facilitate the extracellular electron transfer from the bacteria to the anode. A microbial fuel cell (MFC) equipped with the rGO/MnO2/CF anode delivered a maximum power density of 2065mWm(-2), 154% higher than that with a bare CF anode. The internal resistance of the MFC with this novel anode was 79Ω, 66% lower than the regular one's (234Ω). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses affirmed that the rGO/MnO2 composite significantly increased the anodic reaction rates and facilitated the electron transfer from the bacteria to the anode. The findings from this study suggest that the rGO/MnO2/CF anode, fabricated via a simple dip-coating and electro-deposition process, could be a promising anode material for high-performance MFC applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Anode and cathode geometry and shielding gas interdependence in GTAW

International Nuclear Information System (INIS)

Key, J.F.

1979-01-01

Parametric analyses and high-speed photography of the interdependence of electrode (cathode) tip geometry, shielding gas composition, and groove (anode) geometry indicate that spot-on-plate tests show that blunt cathode shapes have penetration effects similar to addition of a high ionization potential inert gas (such as helium) to the argon shielding gas. Electrode shape and shielding gas composition effects are not synergistic. The time required to develop a given penetration is a function of anode and cathode geometry and shielding gas composition, in addition to other essential welding variables. Spot-on-plate tests are a valid analysis of radical pulsed GTAW. Bead-on-plate tests are a valid analysis of mild pulsed or constant current GTAW

Graphene–sponges as high-performance low-cost anodes for microbial fuel cells

KAUST Repository

Xie, Xing

2012-01-01

A high-performance microbial fuel cell (MFC) anode was constructed from inexpensive materials. Key components were a graphene-sponge (G-S) composite and a stainless-steel (SS) current collector. Anode fabrication is simple, scalable, and environmentally friendly, with low energy inputs. The SS current collector improved electrode conductivity and decreased voltage drop and power loss. The resulting G-S-SS composite electrode appears promising for large-scale applications. © 2012 The Royal Society of Chemistry.

A novel ZnO@Ag@Polypyrrole hybrid composite evaluated as anode material for zinc-based secondary cell

Science.gov (United States)

Huang, Jianhang; Yang, Zhanhong; Feng, Zhaobin; Xie, Xiaoe; Wen, Xing

2016-04-01

A novel ZnO@Ag@Polypyrrole nano-hybrid composite has been synthesized with a one-step approach, in which silver-ammonia complex ion serves as oxidant to polymerize the pyrrole monomer. X-ray diffraction (XRD) and infrared spectroscopy (IR) show the existence of metallic silver and polypyrrole. The structure of nano-hybrid composites are characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), which demonstrates that the surface of ZnO is decorated with nano silver grain coated with polypyrrole. When evaluated as anode material, the silver grain and polypyrrole layer not only suppress the dissolution of discharge product, but also helps to uniform electrodeposition due to substrate effect and its good conductivity, thus shows better cycling performance than bare ZnO electrode does.

Study on preparation of SnO2-TiO2/Nano-graphite composite anode and electro-catalytic degradation of ceftriaxone sodium.

Science.gov (United States)

Guo, Xiaolei; Wan, Jiafeng; Yu, Xiujuan; Lin, Yuhui

2016-12-01

In order to improve the electro-catalytic activity and catalytic reaction rate of graphite-like material, Tin dioxide-Titanium dioxide/Nano-graphite (SnO 2 -TiO 2 /Nano-G) composite was synthesized by a sol-gel method and SnO 2 -TiO 2 /Nano-G electrode was prepared in hot-press approach. The composite was characterized by X-ray photoelectron spectroscopy, fourier transform infrared, Raman, N 2 adsorption-desorption, scanning electrons microscopy, transmission electron microscopy and X-ray diffraction. The electrochemical performance of the SnO 2 -TiO 2 /Nano-G anode electrode was investigated via cyclic voltammetry and electrochemical impedance spectroscopy. The electro-catalytic performance was evaluated by the degradation of ceftriaxone sodium and the yield of ·OH radicals in the reaction system. The results demonstrated that TiO 2 , SnO 2 and Nano-G were composited successfully, and TiO 2 and SnO 2 particles dispersed on the surface and interlamination of the Nano-G uniformly. The specific surface area of SnO 2 modified anode was higher than that of TiO 2 /Nano-G anode and the degradation rate of ceftriaxone sodium within 120 min on SnO 2 -TiO 2 /Nano-G electrode was 98.7% at applied bias of 2.0 V. The highly efficient electro-chemical property of SnO 2 -TiO 2 /Nano-G electrode was attributed to the admirable conductive property of the Nano-G and SnO 2 -TiO 2 /Nano-G electrode. Moreover, the contribution of reactive species ·OH was detected, indicating the considerable electro-catalytic activity of SnO 2 -TiO 2 /Nano-G electrode. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mass-producible method for preparation of a carbon-coated graphite@plasma nano-silicon@carbon composite with enhanced performance as lithium ion battery anode

International Nuclear Information System (INIS)

Chen, Hedong; Wang, Zhoulu; Hou, Xianhua; Fu, Lijun; Wang, Shaofeng; Hu, Xiaoqiao; Qin, Haiqing; Wu, Yuping

2017-01-01

Carbon-coated core-shell structure artificial graphite@plasma nano-silicon@carbon (AG@PNSi@C) composite, applying as lithium ion battery anode material, has been prepared via spray drying method. The plasma nano-silicon (<100 nm), which contained amorphous silicon, was synthesized by radio frequency induction plasma system with the high temperatures processing capability and high quench rates. The artificial graphite in the composite acts as the core which supports the particle and provides electroconductivity, while PNSi attached on the surface of the core, enhances the specific capacity of the composite. The as prepared composite shows superior performance as anode in lithium-ion batteries, regarding to the initial Coulombic efficiency and cycle life. The initial Coulombic efficiency of AG@PNSi@C electrode is 81.0% with a discharge capacity of 553 mAh g −1 and a recharge capacity of 448 mAh g −1 . During cycling, AG@PNSi@C exhibits excellent performance with a very low capacity fading that the discharge capacity maintains 498.2 mAh g −1 and 449.4 mAh g −1 after 250 cycles and 500 cycles. AG@PNSi@C also shows enhanced resistance against high current density. Besides the remarkable electrochemical performances, the facile and mass-producible synthesis process makes the AG@PNSi@C composite very promising for its application in lithium-ion batteries.

Ni-SDC cermet anode for medium-temperature solid oxide fuel cell with lanthanum gallate electrolyte

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xinge; Ohara, Satoshi; Maric, R.; Mukai, Kazuo; Fukui, Takehisa [Japan Fine Ceramics Center, Nagoya (Japan); Yoshida, Hiroyuki; Nishimura, Masayoshi; Inagaki, Toru [Kansai Electr. Power Co. Inc., Hyogo (Japan); Miura, Kazuhiro [Kanden Kakou, Amagasaki (Japan)

1999-10-01

The polarization properties and microstructure of Ni-SDC (samaria-doped ceria) cermet anodes prepared from spray pyrolysis (SP) composite powder, and element interface diffusion between the anode and a La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM) electrolyte are investigated as a function of anode sintering temperature. The anode sintered at 1250 C displays minimum anode polarization (with anode ohmic loss), while the anode prepared at 1300 C has the best electrochemical overpotential, viz., 27 mV at 300 mA cm{sup -2} operating at 800 C. The anode ohmic loss gradually increases with increase in the sintering temperature at levels below 1300 C, and sharply increases at 1350 C. Electron micrographs show a clear grain growth at sintering temperatures higher than 1300 C. The anode microstructure appears to be optimized at 1300 C, in which nickel particles form a network with well-connected SDC particles finely distributed over the surfaces of the nickel particles. The anode sintered at 1350 C has severe grain growth and an apparent interface diffusion of nickel from the anode to the electrolyte. The nickel interface diffusion is assumed to be the main reason for the increment in ohmic loss, and the resulting loss in anode performance. The findings suggest that sintering Ni-SDC composite powder near 1250 C is the best method to prepare the anode on a LSGM electrolyte. (orig.)

Ni-SDC cermet anode for medium-temperature solid oxide fuel cell with lanthanum gallate electrolyte

Science.gov (United States)

Zhang, Xinge; Ohara, Satoshi; Maric, Radenka; Mukai, Kazuo; Fukui, Takehisa; Yoshida, Hiroyuki; Nishimura, Masayoshi; Inagaki, Toru; Miura, Kazuhiro

The polarization properties and microstructure of Ni-SDC (samaria-doped ceria) cermet anodes prepared from spray pyrolysis (SP) composite powder, and element interface diffusion between the anode and a La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ (LSGM) electrolyte are investigated as a function of anode sintering temperature. The anode sintered at 1250°C displays minimum anode polarization (with anode ohmic loss), while the anode prepared at 1300°C has the best electrochemical overpotential, viz., 27 mV at 300 mA cm -2 operating at 800°C. The anode ohmic loss gradually increases with increase in the sintering temperature at levels below 1300°C, and sharply increases at 1350°C. Electron micrographs show a clear grain growth at sintering temperatures higher than 1300°C. The anode microstructure appears to be optimized at 1300°C, in which nickel particles form a network with well-connected SDC particles finely distributed over the surfaces of the nickel particles. The anode sintered at 1350°C has severe grain growth and an apparent interface diffusion of nickel from the anode to the electrolyte. The nickel interface diffusion is assumed to be the main reason for the increment in ohmic loss, and the resulting loss in anode performance. The findings suggest that sintering Ni-SDC composite powder near 1250°C is the best method to prepare the anode on a LSGM electrolyte.

Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells

Directory of Open Access Journals (Sweden)

Henry Fonda Aritonang

2017-05-01

Full Text Available Highly dispersed platinum (Pt nanoparticles / multiwalled carbon nanotubes (MWCNTs on bacterial cellulose (BC as anode catalysts for proton exchange membrane fuel cells (PEMFC were prepared with various precursors and their electro-catalytic activities towards hydrogen oxidation at 70 oC under non-humidified conditions. The composite was prepared by deposition of Pt nanoparticles and MWCNTs on BC gel by impregnation method using a water solution of metal precursors and MWCNTs followed by reducing reaction using a hydrogen gas. The composite was characterized by using TEM (transmission electron microscopy, EDS (energy dispersive spectroscopy, and XRD (X-ray diffractometry techniques. TEM images and XRD patterns both lead to the observation of spherical metallic Pt nanoparticles with mean diameter of 3-11 nm well impregnated into the BC fibrils. Preliminary tests on a single cell indicate that renewable BC is a good prospect to be explored as a membrane in fuel cell field. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 26th February 2017; Accepted: 27th February 2017 How to Cite: Aritonang, H.F., Kamu, V.S., Ciptati, C., Onggo, D., Radiman, C.L. (2017. Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 287-292 (doi:10.9767/bcrec.12.2.803.287-292 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.803.287-292

Metal hydride compositions and lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Young, Kwo; Nei, Jean

2018-04-24

Heterogeneous metal hydride (MH) compositions comprising a main region comprising a first metal hydride and a secondary region comprising one or more additional components selected from the group consisting of second metal hydrides, metals, metal alloys and further metal compounds are suitable as anode materials for lithium ion cells. The first metal hydride is for example MgH.sub.2. Methods for preparing the composition include coating, mechanical grinding, sintering, heat treatment and quenching techniques.

Fe3O4/C composite with hollow spheres in porous 3D-nanostructure as anode material for the lithium-ion batteries

Science.gov (United States)

Yang, Zhao; Su, Danyang; Yang, Jinping; Wang, Jing

2017-09-01

3d transition-metal oxides, especially Fe3O4, as anode materials for the lithium-ion batteries have been attracting intensive attentions in recent years due to their high energy capacity and low toxicity. A new Fe3O4/C composite with hollow spheres in porous three-dimensional (3D) nanostructure, which was synthesized by a facile solvothermal method using FeCl3·6H2O and porous spongy carbon as raw materials. The specific surface area and microstructures of composite were characterized by nitrogen adsorption-desorption isotherm method, FE-SEM and HR-TEM. A homogeneous distribution of hollow Fe3O4 spheres (diameter ranges from 120 nm to 150 nm) in the spongy carbon (pore size > 200 nm) conductive 3D-network significantly reduced the lithium-ion diffusion length and increased the electrochemical reaction area, and further more enhanced the lithium ion battery performance, such as discharge capacity and cycle life. As an anode material for the lithium-ion battery, the title composite exhibit excellent electrochemical properties. The Fe3O4/C composite electrode achieved a relatively high reversible specific capacity of 1450.1 mA h g-1 in the first cycle at 100 mA g-1, and excellent rate capability (69% retention at 1000 mA g-1) with good cycle stability (only 10% loss after 100 cycles).

Iron-antimony-based hybrid oxides as high-performance anodes for lithium-ion storage

Science.gov (United States)

Nguyen, Tuan Loi; Kim, Doo Soo; Hur, Jaehyun; Park, Min Sang; Yoon, Sukeun; Kim, Il Tae

2018-06-01

We report a facile approach to synthesize Fe-Sb-based hybrid oxides nanocomposites consisting of Sb, Sb2O3, and Fe3O4 for use as new anode materials for lithium-ion batteries. The composites are synthesized via galvanic replacement between Fe3+ and Sb at high temperature in triethylene glycol medium. The phase, morphology, and composition changes of the composites involved in the various stages of the replacement reaction are characterized using X-ray diffractometry, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The as-prepared composites have different compositions with very small particle sizes (interfacial contact area between the nanocomposite and electrolyte, stable structure of the composites owing to a mixture of inactive phases generated by the conversion reaction between Li+ and oxide metal-whose structure serves as an electron conductor, inhibits agglomeration of Sb particles, and acts as an effective buffer against volume change of Sb during cycling-and high Li+ diffusion ability.

Characterization of electrical discharges during spark anodization of zirconium in different electrolytes

International Nuclear Information System (INIS)

Santos, Janaina S.; Lemos, Sherlan G.; Gonçalves, Wesley N.; Bruno, Odemir M.; Pereira, Ernesto C.

2014-01-01

The evolution of the electrical discharges parameters during spark anodization of metallic Zr under galvanostatic regime have been investigated by image analysis in phosphoric and oxalic acid electrolytes. The experiments were recorder using a high-speed video camera during the entire anodization with a resolution of 1.7 ms for determination of discharge lifetime and a standard resolution of 33 ms (real-time imaging) for determination of the average area and discharge population density. The discharge behavior was dependent of the current density, electrolyte composition and anodization time. During breakdown process, sparks discharges are progressively turned to micro-arcs, which can be seen by enlargement of discharge area, gradual increase of lifetime and reduction of discharge population density. A factorial design was used to estimate the effects of experimental conditions on the discharge behavior. The current density and electrolyte composition were the most important factors that affected the discharge population density. The anodization time and the electrolyte composition were the main factor that influenced the discharge area and lifetime. In comparison with the voltage vs. time curve, the results demonstrate important features of the process and the changes of the electrical discharges characteristics during the experiments

Effects of anodizing conditions and annealing temperature on the morphology and crystalline structure of anodic oxide layers grown on iron

Science.gov (United States)

Pawlik, Anna; Hnida, Katarzyna; Socha, Robert P.; Wiercigroch, Ewelina; Małek, Kamilla; Sulka, Grzegorz D.

2017-12-01

Anodic iron oxide layers were formed by anodization of the iron foil in an ethylene glycol-based electrolyte containing 0.2 M NH4F and 0.5 M H2O at 40 V for 1 h. The anodizing conditions such as electrolyte composition and applied potential were optimized. In order to examine the influence of electrolyte stirring and applied magnetic field, the anodic samples were prepared under the dynamic and static conditions in the presence or absence of magnetic field. It was shown that ordered iron oxide nanopore arrays could be obtained at lower anodizing temperatures (10 and 20 °C) at the static conditions without the magnetic field or at the dynamic conditions with the applied magnetic field. Since the as-prepared anodic layers are amorphous in nature, the samples were annealed in air at different temperatures (200-500 °C) for a fixed duration of time (1 h). The morphology and crystal phases developed after anodization and subsequent annealing were characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The results proved that the annealing process transforms the amorphous layer into magnetite and hematite phases. In addition, the heat treatment results in a substantial decrease in the fluorine content and increase in the oxygen content.

Mesoporous Silicon-Based Anodes for High Capacity, High Performance Li-ion Batteries, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A new high capacity anode composite based on mesoporous silicon is proposed. By virtue of a structure that resembles a pseudo one-dimensional phase, the active anode...

Investigation of anodic TiO2 nanotube composition with high spatial resolution AES and ToF SIMS

Science.gov (United States)

Dronov, Alexey; Gavrilin, Ilya; Kirilenko, Elena; Dronova, Daria; Gavrilov, Sergey

2018-03-01

High resolution Scanning Auger Electron Spectroscopy (AES) and Time-of-Flight Secondary Ion Mass-Spectrometry (ToF SIMS) were used to investigate structure and elemental composition variation of both across an array of TiO2 nanotubes (NTs) and single tube of an array. The TiO2 NT array was grown by anodic oxidation of Ti foil in fluorine-containing ethylene glycol electrolyte. It was found that the studied anodic TiO2 nanotubes have a layered structure with rather sharp interfaces. The differences in AES depth profiling results of a single tube with the focused primary electron beam (point analysis) and over an area of 75 μm in diameter of a nanotube array with the defocused primary electron beam are discussed. Depth profiling by ToF SIMS was carried out over approximately the same size of a nanotube array to determine possible ionic fragments in the structure. The analysis results show that the combination of both mentioned methods is useful for a detailed analysis of nanostructures with complex morphology and multi-layered nature.

Preparation and characterization of Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide formed by cathodic electroplating and anodizing

Energy Technology Data Exchange (ETDEWEB)

Jang, Joo-Hee; Kim, Tae-Yoo; Kim, Nam-Jeong; Lee, Chang-Hyoung; Park, Eun-Mi [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, Chan [Division of Materials Science and Engineering, Pukyong National University, Busan 608-739 (Korea, Republic of); Suh, Su-Jeong, E-mail: suhsj@skku.ac.kr [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Advanced Materials and Process Research Center for IT, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2011-11-15

Highlights: > We fabricate Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3}/Al film for high performance thin film capacitor. > The optimum condition of electrolyte composition will coat NbO{sub x} on Al without corrosion of Al during the cathodic electroplating. > Increasing annealing temperature will form Nb{sub 2}O{sub 5} crystalline. > The Al{sub 2}O{sub 3} layer will form between Nb{sub 2}O{sub 5} layer and metal Al after anodizing and the thin film capacitor with Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3}/Al improve dielectric properties. - Abstract: Al foil was coated with niobium oxide by cathodic electroplating and anodized in a neutral boric acid solution to achieve high capacitance in a thin film capacitor. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed the niobium oxide layer on Al to be a hydroxide-rich amorphous phase. The film was crystalline and had stoichiometric stability after annealing at temperatures up to 600 deg. C followed by anodizing at 500 V, and the specific capacitance of the Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide was approximately 27% higher than that of Al{sub 2}O{sub 3} without a Nb{sub 2}O{sub 5} layer. The capacitance was quite stable to the resonance frequency. Overall, the Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide film is a suitable material for thin film capacitors.

Carbon-covered Fe{sub 3}O{sub 4} hollow cubic hierarchical porous composite as the anode material for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Chen, Shouhui, E-mail: csh2k@jxnu.edu.cn; Zhou, Rihui; Chen, Yaqin; Fu, Yuanyuan; Li, Ping; Song, Yonghai; Wang, Li, E-mail: lwanggroup@aliyun.com [Jiangxi Normal University, College of Chemistry and Chemical Engineering (China)

2017-04-15

In this work, Prussian blue nanocrystals, a kind of cubic metal-organic frameworks, was firstly covered by a uniform layer of resorcinol-formaldehyde (RF) resin, and then followed with heat treatment at different pyrolysis temperatures. The effects of pyrolysis temperature on the morphologies, phase, pore size, and electrochemical performance of the pyrolysis products were studied in this work. The composite generated at 600 {sup ∘}C, FexC600, was a hollow cubic composite of Fe{sub 3}O{sub 4} covered by a thin RF-derived carbon layer. The carbon layer on FexC600 was a robust and conductive protective layer, which can accommodate Fe{sub 3}O{sub 4} NPs and withstand the huge volume change of Fe{sub 3}O{sub 4} during the process of discharge and charge. When used as anodes for lithium-ion batteries, FexC600 showed excellent electrochemical performance. It delivered a discharge capacity of 1126 mAh g{sup −1} with a coulombic efficiency of 98.8% at the current density of 100 mA g{sup −1} after 100 times discharge/charge cycling. It even delivered a capacity of 492 mAh g{sup −1} at the current density of 500 mA g{sup −1}. This cubic hollow composite would be a promising alternative anode material for lithium-ion batteries.

Effect of anodic surface treatment on PAN-based carbon fiber and its relationship to the fracture toughness of the carbon fiber-reinforced polymer composites

DEFF Research Database (Denmark)

Sarraf, Hamid; Skarpova, Ludmila

2008-01-01

The effect of anodic surface treatment on the polyacrylonitrile (PAN)-based carbon fibers surface properties and the mechanical behavior of the resulting carbon fiber-polymer composites has been studied in terms of the contact angle measurements of fibers and the fracture toughness of composites...... in the fiber surface nature and the mechanical interfacial properties between the carbon fiber and epoxy resin matrix of the resulting composites, i.e., the fracture toughness. We suggest that good wetting plays an important role in improving the degree of adhesion at interfaces between fibers and matrices...

Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

Science.gov (United States)

Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg

2017-02-07

The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

Synthesis of novel spherical Fe_3O_4@Ni_3S_2 composite as improved anode material for rechargeable nickel-iron batteries

International Nuclear Information System (INIS)

Li, Jing; Guo, Litan; Shangguan, Enbo; Yue, Mingzhu; Xu, Min; Wang, Dong; Chang, Zhaorong; Li, Quanmin

2017-01-01

Highlights: • Fe_3O_4@Ni_3S_2 microspheres are fabricated through a facile method for the first time. • Fe_3O_4@Ni_3S_2 is firstly proposed as alkaline anode materials for Ni/Fe batteries. • Fe_3O_4@Ni_3S_2 shows enhanced high-rate capability and improved cycle stability. • Ni_3S_2 can suppress the passivation and hydrogen evolution behavior of the iron anode. - Abstract: Fe_3O_4@Ni_3S_2 microspheres as a novel alkaline anode material have been successfully fabricated through a four-step process for the first time. In this composite, Ni_3S_2 nanoparticles are coated tightly on the surface of Fe_3O_4 microspheres. Compared with the pure Fe_3O_4 and Fe_3O_4@NiO microspheres, the proposed Fe_3O_4@Ni_3S_2 delivers a significantly improved high-rate performance and enhanced cycling stability. At a high discharge rate of 1200 mA g"−"1, the specific capacity of the Fe_3O_4@Ni_3S_2 is ∼481.2 mAh g"−"1 in comparison with ∼83.7 mAh g"−"1 for the pure Fe_3O_4. After 100 cycles at 120 mA g"−"1, the Fe_3O_4@Ni_3S_2 can achieve a capacity retention of 95.1%, while the value for the pure Fe_3O_4 electrode is only 52.5%. The favorable electrochemical performance of the Fe_3O_4@Ni_3S_2 is mainly attributed to the beneficial impact of Ni_3S_2. The Ni_3S_2 layer as a useful additive is significantly conducive to lessening the formation of Fe(OH)_2 passivation layer, enhancing the electronic conductivity, improving the reaction reversibility and suppressing the hydrogen evolution reaction of the alkaline iron anode. Owing to its outstanding electrochemical properties, we believe that the novel Fe_3O_4@Ni_3S_2 composite is potentially a promising candidate for anode material of alkaline iron-based batteries.

Copper based anodes for bio-ethanol fueled low-temperature solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Kondakindi, R.R.; Karan, K. [Queen' s Univ., Kingston, ON (Canada)

2003-07-01

Laboratory studies have been conducted to develop a low-temperature solid oxide fuel cell (SOFC) fueled by bio-ethanol. SOFCs are considered to be a potential source for clean and efficient electricity. The use of bio-ethanol to power the SOFC contributes even further to reducing CO{sub 2} emissions. The main barrier towards the development of the proposed SOFC is the identification of a suitable anode catalyst that prevents coking during electro-oxidation of ethanol while yielding good electrical performance. Copper was selected as the catalyst for this study. Composite anodes consisting of copper catalysts and gadolinium-doped ceria (GDC) electrolytes were prepared using screen printing of GDC and copper oxide on dense GDC electrolytes and by wet impregnation of copper nitrate in porous GDC electrolytes followed by calcination and sintering. The electrical conductivity of the prepared anodes was characterized to determine the percolation threshold. Temperature-programmed reduction and the Brunner Emmett Teller (BET) methods were used to quantify the catalyst dispersion and surface area. Electrochemical performance of the single-cell SOFC with a hydrogen-air system was used to assess the catalytic activities. Electrochemical Impedance Spectroscopy was used to probe the electrode kinetics.

Plasma synthesis of titanium nitride, carbide and carbonitride nanoparticles by means of reactive anodic arc evaporation from solid titanium

International Nuclear Information System (INIS)

Kiesler, D.; Bastuck, T.; Theissmann, R.; Kruis, F. E.

2015-01-01

Plasma methods using the direct evaporation of a transition metal are well suited for the cost-efficient production of ceramic nanoparticles. In this paper, we report on the development of a simple setup for the production of titanium-ceramics by reactive anodic arc evaporation and the characterization of the aerosol as well as the nanopowder. It is the first report on TiC X N 1 − X synthesis in a simple anodic arc plasma. By means of extensive variations of the gas composition, it is shown that the composition of the particles can be tuned from titanium nitride over a titanium carbonitride phase (TiC X N 1 − X ) to titanium carbide as proven by XRD data. The composition of the plasma gas especially a very low concentration of hydrocarbons around 0.2 % of the total plasma gas is crucial to tune the composition and to avoid the formation of free carbon. Examination of the particles by HR-TEM shows that the material consists mostly of cubic single crystalline particles with mean sizes between 8 and 27 nm

Composition consisting of a dendrimer and an active substance

NARCIS (Netherlands)

1995-01-01

The invention relates to a composition consisting of a dendrimer provided with blocking agents and an active substance occluded in the dendrimer. According to the invention a blocking agent is a compound which is sterically of sufficient size, which readily enters into a chemical bond with the

Anodic oxidation of InP in pure water

International Nuclear Information System (INIS)

Robach, Y.; Joseph, J.; Bergignat, E.; Hollinger, G.

1989-01-01

It is shown that thin InP native oxide films can be grown by anodization of InP in pure water. An interfacial phosphorus-rich In(PO 3 ) 3 -like condensed phosphate is obtained this way. This condensed phosphate has good passivating properties and can be used in electronic device technology. The chemical composition of these native oxides was found similar to that of an anodic oxide grown in an anodization in glycol and water (AGW) electrolyte. From the similarity between the two depth profiles observed in pure water and AGW electrolyte, they can conclude that dissolution phenomena do not seem to play a major role. The oxide growth seems to be controlled by the drift of ionic species under the electric field

Promising Ni-Fe-LSGMC anode compatible with lanthanum gallate electrolyte

Energy Technology Data Exchange (ETDEWEB)

Wang Shizhong [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)], E-mail: shizwang@sohu.com; He, Qiong [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu Meilin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)], E-mail: meilin.liu@mse.gatech.edu

2009-06-01

A number of composite materials in the Ni-Fe-LSGMC family have been studied as potential anodes for solid oxide fuel cells (SOFCs) based on strontium, magnesium, and cobalt doped lanthanum gallate electrolyte (LSGMC). The results show that Ni reacts with LSGMC especially under reducing conditions at high temperatures, resulting in high contact resistance, large electrode polarization, and poor performance. The reaction between Ni and LSGMC depends strongly on the composition and pre-sintering temperature of LSGMC, the concentration of iron in the electrode, and the processing and operating temperatures. Under proper conditions, Ni-Fe-LSGMC5 could be a promising high-performance anode with good compatibility with LSGMC5 electrolyte.

Promising Ni-Fe-LSGMC anode compatible with lanthanum gallate electrolyte

International Nuclear Information System (INIS)

Wang Shizhong; He, Qiong; Liu Meilin

2009-01-01

A number of composite materials in the Ni-Fe-LSGMC family have been studied as potential anodes for solid oxide fuel cells (SOFCs) based on strontium, magnesium, and cobalt doped lanthanum gallate electrolyte (LSGMC). The results show that Ni reacts with LSGMC especially under reducing conditions at high temperatures, resulting in high contact resistance, large electrode polarization, and poor performance. The reaction between Ni and LSGMC depends strongly on the composition and pre-sintering temperature of LSGMC, the concentration of iron in the electrode, and the processing and operating temperatures. Under proper conditions, Ni-Fe-LSGMC5 could be a promising high-performance anode with good compatibility with LSGMC5 electrolyte.

Facile synthesis and stable cycling ability of hollow submicron silicon oxide–carbon composite anode material for Li-ion battery

Energy Technology Data Exchange (ETDEWEB)

Kim, Joong-Yeon; Nguyen, Dan Thien [Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kang, Joon-Sup [Department of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Song, Seung-Wan, E-mail: swsong@cnu.ac.kr [Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Department of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2015-06-05

Highlights: • Hollow submicron SiO{sub 2}–carbon composite material was synthesized using Si{sup 4+}-citrate chelation. • Composite material possessed a homogeneous distribution of SiO{sub 2} and carbon. • Composite electrode delivered ⩾600 mAh/g with a stable cycling stability. • This materials design and synthesis provides a useful platform for scalable production. - Abstract: Advanced SiO{sub 2}–carbon composite anode active material for lithium-ion battery has been synthesized through a simple chelation of silicon cation with citrate in a glyme-based solvent. The resultant composite material demonstrates a homogeneous distribution of constituents over the submicron particles and a unique hollow spherical microstructure, which provides an enhanced electrical conductivity and better accommodation of volume change of silicon during electrochemical charge–discharge cycling, respectively. As a result, the composite electrode exhibits a high cycling stability delivering the capacity retention of 91% at the 100th cycle and discharge capacities of 662–602 mAh/g and coulombic efficiencies of 99.8%. This material synthesis is scalable and cost-effective in preparing various submicron or micron composite electrode materials.

Carbon paint anode for reinforced concrete bridges in coastal environments

Energy Technology Data Exchange (ETDEWEB)

Cramer, Stephen D.; Bullard, Sophie J.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Cryer, C.B. (ODOT); Laylor, H.M. (ODOT)

2002-01-01

Solvent-based acrylic carbon paint anodes were installed on the north approach spans of the Yaquina Bay Bridge (Newport OR) in 1985. The anodes continue to perform satisfactorily after more than 15 years service. The anodes were inexpensive to apply and field repairs are easily made. Depolarization potentials are consistently above 100 mV with long-term current densities around 2 mA/m 2. Bond strength remains adequate, averaging 0.50 MPa (73 psi). Some deterioration of the anode-concrete interface has occurred in the form of cracks and about 4% of the bond strength measurements indicated low or no bond. Carbon anode consumption appears low. The dominant long-term anode reaction appears to be chlorine evolution, which results in limited further acidification of the anode-concrete interface. Chloride profiles were depressed compared to some other coastal bridges suggesting chloride extraction by the CP system. Further evidence of outward chloride migration was a flat chloride profile between the anode and the outer rebar.

Chromic acid anodizing of aluminum foil

Science.gov (United States)

Dursch, H.

1988-01-01

The success of the Space Station graphite/epoxy truss structure depends on its ability to endure long-term exposure to the LEO environment, primarily the effects of atomic oxygen and the temperture cycling resulting from the 94 minute orbit. This report describes the development and evaluation of chromic acid anodized (CAA) aluminum foil as protective coatings for these composite tubes. Included are: development of solar absorptance and thermal emittance properties required of Al foil and development of CAA parameters to achieve these optical properties; developing techniques to CAA 25 ft lengths of Al foil; developing bonding processes for wrapping the Al foil to graphite/epoxy tubes; and atomic oxygen testing of the CAA Al foil. Two specifications were developed and are included in the report: Chromic Acid Anodizing of Aluminum Foil Process Specification and Bonding of Anodized Aluminum Foil to Graphite/Epoxy Tubes. Results show that CAA Al foil provides and excellent protective and thermal control coating for the Space Station truss structure.

Air plasma spray processing and electrochemical characterization of Cu-SDC coatings for use in solid oxide fuel cell anodes

Energy Technology Data Exchange (ETDEWEB)

Benoved, Nir [Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Sciences Lane, Vancouver, British Columbia (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario (Canada)

2009-09-05

Air plasma spraying has been used to produce porous composite anodes based on Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9} (SDC) and Cu for use in solid oxide fuel cells (SOFCs). Preliminarily, a range of plasma conditions has been examined for the production of composite coatings from pre-mixed SDC and CuO powders. Plasma gas compositions were varied to obtain a range of plasma temperatures. After reduction in H{sub 2}, coatings were characterized for composition and microstructure using EDX and SEM. As a result of these tests, symmetrical sintered electrolyte-supported anode-anode cells were fabricated by air plasma spraying of the anodes, followed by in situ reduction of the CuO to Cu. Full cells deposited on SS430 porous substrates were then produced in one integrated process. Fine CuO and SDC powders have been used to produce homogeneously mixed anode coatings with higher surface area microstructures, resulting in area-specific polarization resistances of 4.8 {omega} cm{sup 2} in impedance tests in hydrogen at 712 C. (author)

Air plasma spray processing and electrochemical characterization of Cu-SDC coatings for use in solid oxide fuel cell anodes

Science.gov (United States)

Benoved, Nir; Kesler, O.

Air plasma spraying has been used to produce porous composite anodes based on Ce 0.8Sm 0.2O 1.9 (SDC) and Cu for use in solid oxide fuel cells (SOFCs). Preliminarily, a range of plasma conditions has been examined for the production of composite coatings from pre-mixed SDC and CuO powders. Plasma gas compositions were varied to obtain a range of plasma temperatures. After reduction in H 2, coatings were characterized for composition and microstructure using EDX and SEM. As a result of these tests, symmetrical sintered electrolyte-supported anode-anode cells were fabricated by air plasma spraying of the anodes, followed by in situ reduction of the CuO to Cu. Full cells deposited on SS430 porous substrates were then produced in one integrated process. Fine CuO and SDC powders have been used to produce homogeneously mixed anode coatings with higher surface area microstructures, resulting in area-specific polarization resistances of 4.8 Ω cm 2 in impedance tests in hydrogen at 712 °C.

Online gas composition estimation in solid oxide fuel cell systems with anode off-gas recycle configuration

Science.gov (United States)

Dolenc, B.; Vrečko, D.; Juričić, Ð.; Pohjoranta, A.; Pianese, C.

2017-03-01

Degradation and poisoning of solid oxide fuel cell (SOFC) stacks are continuously shortening the lifespan of SOFC systems. Poisoning mechanisms, such as carbon deposition, form a coating layer, hence rapidly decreasing the efficiency of the fuel cells. Gas composition of inlet gases is known to have great impact on the rate of coke formation. Therefore, monitoring of these variables can be of great benefit for overall management of SOFCs. Although measuring the gas composition of the gas stream is feasible, it is too costly for commercial applications. This paper proposes three distinct approaches for the design of gas composition estimators of an SOFC system in anode off-gas recycle configuration which are (i.) accurate, and (ii.) easy to implement on a programmable logic controller. Firstly, a classical approach is briefly revisited and problems related to implementation complexity are discussed. Secondly, the model is simplified and adapted for easy implementation. Further, an alternative data-driven approach for gas composition estimation is developed. Finally, a hybrid estimator employing experimental data and 1st-principles is proposed. Despite the structural simplicity of the estimators, the experimental validation shows a high precision for all of the approaches. Experimental validation is performed on a 10 kW SOFC system.

Atomic Layer Deposition of SnO2 on MXene for Li-Ion Battery Anodes

KAUST Repository

Ahmed, Bilal; Anjum, Dalaver H.; Gogotsi, Yury; Alshareef, Husam N.

2017-01-01

In this report, we show that oxide battery anodes can be grown on two-dimensional titanium carbide sheets (MXenes) by atomic layer deposition. Using this approach, we have fabricated a composite SnO2/MXene anode for Li-ion battery applications

Phase III Advanced Anodes and Cathodes Utilized in Energy Efficient Aluminum Production Cells; FINAL

International Nuclear Information System (INIS)

Christini, R.A.; Dawless, R.K.; Ray, S.P.; Weirauch, D.A. Jr.

2001-01-01

During Phase I of the present program, Alcoa developed a commercial cell concept that has been estimated to save 30% of the energy required for aluminum smelting. Phase ii involved the construction of a pilot facility and operation of two pilots. Phase iii of the Advanced Anodes and Cathodes Program was aimed at bench experiments to permit the resolution of certain questions to be followed by three pilot cells. All of the milestones related to materials, in particular metal purity, were attained with distinct improvements over work in previous phases of the program. NiO additions to the ceramic phase and Ag additions to the Cu metal phase of the cermet improved corrosion resistance sufficiently that the bench scale pencil anodes met the purity milestones. Some excellent metal purity results have been obtained with anodes of the following composition: Further improvements in anode material composition appear to be dependent on a better understanding of oxide solubilities in molten cryolite. For that reason, work was commissioned with an outside consultant to model the MeO - cryolite systems. That work has led to a better understanding of which oxides can be used to substitute into the NiO-Fe2O3 ceramic phase to stabilize the ferrites and reduce their solubility in molten cryolite. An extensive number of vertical plate bench electrolysis cells were run to try to find conditions where high current efficiencies could be attained. TiB2-G plates were very inconsistent and led to poor wetting and drainage. Pure TiB2 did produce good current efficiencies at small overlaps (shadowing) between the anodes and cathodes. This bench work with vertical plate anodes and cathodes reinforced the importance of good cathode wetting to attain high current efficiencies. Because of those conclusions, new wetting work was commissioned and became a major component of the research during the third year of Phase III. While significant progress was made in several areas, much work needs to be

Compositionally graded SiCu thin film anode by magnetron sputtering for lithium ion battery

Energy Technology Data Exchange (ETDEWEB)

Polat, B.D., E-mail: bpolat@itu.edu.tr [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, Istanbul 34469 (Turkey); Eryilmaz, O.L. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Keleş, O., E-mail: ozgulkeles@itu.edu.tr [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, Istanbul 34469 (Turkey); Erdemir, A. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Amine, K. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2015-12-01

Compositionally graded and non-graded composite SiCu thin films were deposited by magnetron sputtering technique on Cu disks for investigation of their potentials in lithium ion battery applications. The compositionally graded thin film electrodes with 30 at.% Cu delivered a 1400 mAh g{sup −1} capacity with 80% Coulombic efficiency in the first cycle and still retained its capacity at around 600 mAh g{sup −1} (with 99.9% Coulombic efficiency) even after 100 cycles. On the other hand, the non-graded thin film electrodes with 30 at.% Cu exhibited 1100 mAh g{sup −1} as the first discharge capacity with 78% Coulombic efficiency but the cycle life of this film degraded very quickly, delivering only 250 mAh g{sup −1} capacity after 100th cycles. Not only the Cu content but also the graded film thickness were believed to be the main contributors to the much superior performance of the compositionally graded SiCu films. We also believe that the Cu-rich region of the graded film helped reduce internal stress build-up and thus prevented film delamination during cycling. In particular, the decrease of Cu content from interface region to the top of the coating reduced the possibility of stress build-up across the film during cycling, thus leading to a high electrochemical performance.b - Highlights: • Highly adherent SiCu films are deposited by magnetron sputtering. • Compositionally graded SiCu film is produced and characterized. • Decrease of Cu content diverted the propagation of stress in the anode. • Cu rich layer at the bottom improves the adherence of the film.

Thin composite films consisting of polypyrrole and polyparaphenylene

International Nuclear Information System (INIS)

Golovtsov, I.; Bereznev, S.; Traksmaa, R.; Opik, A.

2007-01-01

This study demonstrates that the combined method for the formation of thin composite films, consisting of polypyrrole (PPy) as a film forming agent and polyparaphenylene (PPP) with controlled electrical properties and high stability, enables one to avoid the low processability of PPP and to extend the possibilities for the development of electronic devices. The high temperature (250-600 deg. C) doping method was used for PPP preparation. The crystallinity and grindability of PPP was found to be increasing with the thermochemical modification. Thin composite films were prepared onto the light transparent substrates using the simple electropolymerization technique. The properties of films were characterized by the optical transmittance and temperature-dependent conductivity measurements. The morphology and thickness of the prepared films were determined using the scanning electron microscopy. The composite films showed a better adhesion to an inorganic substrate. It was found to be connected mostly with the improved properties of the high temperature doped PPP. The current-voltage characteristics of indium tin oxide/film/Au hybrid organic-inorganic structures showed the influence of the doping conditions of PPP inclusions in the obtained films

An in situ method of creating metal oxide–carbon composites and their application as anode materials for lithium-ion batteries

KAUST Repository

Yang, Zichao

2011-01-01

Transition metal oxides are actively investigated as anode materials for lithium-ion batteries (LIBs), and their nanocomposites with carbon frequently show better performance in galvanostatic cycling studies, compared to the pristine metal oxide. An in situ, scalable method for creating a variety of transition metal oxide-carbon nanocomposites has been developed based on free-radical polymerization and cross-linking of poly(acrylonitrile) in the presence of the metal oxide precursor containing vinyl groups. The approach yields a cross-linked polymer network, which uniformly incorporates nanometre-sized transition metal oxide particles. Thermal treatment of the organic-inorganic hybrid material produces nearly monodisperse metal oxide nanoparticles uniformly embedded in a porous carbon matrix. Cyclic voltammetry and galvanostatic cycling electrochemical measurements in a lithium half-cell are used to evaluate the electrochemical properties of a Fe3O 4-carbon composite created using this approach. These measurements reveal that when used as the anode in a lithium battery, the material exhibits stable cycling performance at both low and high current densities. We further show that the polymer/nanoparticle copolymerization approach can be readily adapted to synthesize metal oxide/carbon nanocomposites based on different particle chemistries for applications in both the anode and cathode of LIBs. © 2011 The Royal Society of Chemistry.

The characteristics of anodic coating of Al-alloy claddings

International Nuclear Information System (INIS)

Yang Yong; Zou Benhui; Guo Hong; Du Yanhua; Bai Zhiyong; Cai Zhenfang

2014-01-01

Aluminum alloy claddings of research reactor fuel elements should be corroded by sodium hydroxide solution and anodized in sulfuric acid solution, but there are often some uneven color phenomena on surfaces, and sometimes regions of 'black and white stripes' appear. In order to study the relationship of colorful stripes on coatings and the surface morphology of aluminum alloy claddings corroded by sodium hydroxide solution, surface microstructures and second phase particles of the aluminum alloy claddings, which were corroded by sodium hydroxide solution, are investigated metallographically and via SEM analysis; Meanwhile, thickness, microstructure, chemical composition and construction of anodic oxidation coatings on aluminum coatings are analyzed. It is shown that: 1) the darker the surface color of corroded aluminum alloy claddings is, the darker of anodic oxidation coating; 2) there are many micro-pores on anodized oxidation coatings, which is much similar to that of corroded aluminum alloy claddings according to the morphology and distribution. So, it can be deduced that the surface morphology of anodic coatings is inherited from the corroded surfaces. (authors)

Hierarchical carambola-like Li4Ti5O12-TiO2 composites as advanced anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Zhang, Yu; Zhang, Yun; Huang, Ling; Zhou, Zhongfu; Wang, Jingfeng; Liu, Heng; Wu, Hao

2016-01-01

Hierarchically structured Li 4 Ti 5 O 12 -TiO 2 (LTO-TiO 2 ) composites are synthesized using a facile hydrothermal approach upon reaction time control. With control over the time of hydrothermal reaction at 18 h, a hierarchical dual-phase LTO-TiO 2 composite with appropriate amount of anatase TiO 2 can be obtained, and it possesses a uniform carambola-like framework assembled by numerous ultrathin nanosheets, which enable a relatively large specific surface area, along with abundant interlayer channels to favor electrolyte penetration. When used as anode materials for lithium-ion batteries, such carambola-like LTO-TiO 2 composite exhibits remarkably improved capacity, high-rate capability, and cycling stability over other LTO-TiO 2 samples, which are synthesized at different time of hydrothermal reaction. Specifically, it deliveries a discharge capacity as high as 115.1 and 91.2 mAh g −1 at a very high current rate of 20 and 40C, respectively, while a stable reversible capacity of 171.7 mAh g −1 can be retained after 200 charge-discharge cycles at 1C, corresponding to 88.6% capacity retention. The excellent electrochemical performances benefit from the unique hierarchical carambola-like structure together with the mutually complementary intrinsic advantages between LTO and TiO 2 . The robust and porous nanosheets-assembled LTO-TiO 2 framework not only offers a shorter transport pathway for electron and Li-ion migration within this composite material, but also is able to alleviate the structure distortion during the fast Li-ion insertion/extraction process. The work described here shows that the hierarchical carambola-like LTO-TiO 2 composite is a promising anode material for high-power and long-life lithium-ion batteries.

Aerosol assisted synthesis of hierarchical tin–carbon composites and their application as lithium battery anode materials

KAUST Repository

Guo, Juchen

2013-01-01

We report a method for synthesizing hierarchically structured tin-carbon (Sn-C) composites via aerosol spray pyrolysis. In this method, an aqueous precursor solution containing tin(ii) chloride and sucrose is atomized, and the resultant aerosol droplets carried by an inert gas are pyrolyzed in a high-temperature tubular furnace. Owing to the unique combination of high reaction temperature and short reaction time, this method is able to achieve a hetero-structure in which small Sn particles (15 nm) are uniformly embedded in a secondary carbon particle. This procedure allows the size and size distribution of the primary Sn particles to be tuned, as well as control over the size of the secondary carbon particles by addition of polymeric surfactant in the precursor solution. When evaluated as anode materials for lithium-ion batteries, the resultant Sn-C composites demonstrate attractive electrochemical performance in terms of overall capacity, electrochemical stability, and coulombic efficiency. © 2013 The Royal Society of Chemistry.

Lithium batteries, anodes, and methods of anode fabrication

KAUST Repository

Li, Lain-Jong

2016-12-29

Prelithiation of a battery anode carried out using controlled lithium metal vapor deposition. Lithium metal can be avoided in the final battery. This prelithiated electrode is used as potential anode for Li- ion or high energy Li-S battery. The prelithiation of lithium metal onto or into the anode reduces hazardous risk, is cost effective, and improves the overall capacity. The battery containing such an anode exhibits remarkably high specific capacity and a long cycle life with excellent reversibility.

Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

OpenAIRE

Kikuchi, Tatsuya; Yamamoto, Tsuyoshi; Natsui, Shungo; Suzuki, Ryosuke O.

2014-01-01

The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M squaric acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200-400...

Designing self-standing silicon-copper composite helices as anodes for lithium ion batteries

International Nuclear Information System (INIS)

Polat, B.D.; Keles, O.

2016-01-01

In this study, we have fabricated helical thin films to be used as an anode material in lithium ion batteries (LIB). The thin films having various Cu−Si atomic ratios (30–70%, 20–80%, and 10–90%) are prepared by using ion-assisted glancing angle co-deposition. Cu plays a crucial role in holding the electrode together, minimizing overall capacity loss and enabling faster electron transfer thus, improving the electrochemical performances of the electrodes. Increasing the Cu/Si atomic ratio affects the structure of the helices and their alignment. Implementing ion assisted deposition at the beginning of the film deposition helps to improve film adhesion. The Si-20 at.% Cu anode delivers 1885 mAh g"−"1 initially with 98% coulombic efficiency and retains 77% of the capacity after 100 cycles at 100 mA g"−"1. - Highlights: • Highly adherent SiCu helices are deposited by ion assisted glancing angle deposition. • Cu content in the SiCu helices affects the helice' morphology and structure. • SiCu helices with different Cu contents have been used as anodes for LIB. • Helices being like microsprings, improve the mechanical resistance of the anode.

Three-dimensional sandwich-structured NiMn2O4@reduced graphene oxide nanocomposites for highly reversible Li-ion battery anodes

Science.gov (United States)

Huang, Jiarui; Wang, Wei; Lin, Xirong; Gu, Cuiping; Liu, Jinyun

2018-02-01

A sandwich-structured NiMn2O4@reduced graphene oxide (NiMn2O4@rGO) nanocomposite consisting of ultrathin NiMn2O4 sheets uniformly anchored on both sides of a three-dimensional (3D) porous rGO is presented. The NiMn2O4@rGO nanocomposites prepared through a dipping process combining with a hydrothermal method show a good electrochemical performance including a high reversible capability of 1384 mAh g-1 at 1000 mA g-1 over 1620 cycles, and an superior rate performance. Thus, a full cell consisting of a commercial LiCoO2 cathode and the NiMn2O4@rGO anode delivers a stable capacity of about 1046 mAh g-1 (anode basis) after cycling at 50 mA g-1 for 60 times. It is demonstrated that the 3D porous composite structure accommodates the volume change during the Li+ insertion/extraction process and facilitates the rapid transport of ions and electrons. The high performance would enable the presented NiMn2O4@rGO nanocomposite a promising anode candidate for practical applications in Li-ion batteries.

Influence of fluorozirconic acid on sulfuric acid anodizing of aluminum

OpenAIRE

Elaish, R.; Curioni, M.; Gowers, K.; Kasuga, A.; Habazaki, H.; Hashimoto, T.; Skeldon, P.

2017-01-01

The effects of additions of fluorozirconic acid to sulfuric acid on the anodizing behavior of aluminum have been investigated under a constant voltage at temperatures of 0 and 20◦C. The fluoroacid increased the rate of film growth, with a dependence on the fluoroacid concentration, the electrolyte temperature and the anodizing time. Compositional analyses showed that fluorine species were present in the films. However, zirconium species were absent. The fluoroacid generally enhanced film diss...

Spectra of luminescence due to microdischarges on an aluminum valve anode

International Nuclear Information System (INIS)

Sizikov, A.M.; Vol'f, V.G.; Bugaenko, L.T.

1995-01-01

The spectrum of visible and near-UV luminescence due to a microdischarge on an AMg-6 aluminum alloy was studied under conditions of valve anodization in solutions of sodium carbonate and other electrolytes. It was shown that emission spectra exhibit lines that characterize anodic (aluminum and magnesium) and electrolytic (sodium) components. The dependence of the temperature of the microdischarge on the electrolyte concentration and composition is discussed

Mechanochemical approaches to employ silicon as a lithium-ion battery anode

International Nuclear Information System (INIS)

Shimoi, Norihiro; Bahena-Garrido, Sharon; Tanaka, Yasumitsu; Qiwu, Zhang

2015-01-01

Silicon is essential as an active material in lithium-ion batteries because it provides both high-charge and optimal cycle characteristics. The authors attempted to realize a composite by a simple mechanochemical grinding approach of individual silicon (Si) particles and copper monoxide (CuO) particles to serve as an active material in the anode and optimize the charge-discharge characteristics of a lithium-ion battery. The composite with Si and CuO allowed for a homogenous dispersion with nano-scale Si grains, nano-scale copper-silicon alloy grains and silicon monoxide oxidized the oxide from CuO. The authors successfully achieved the synthesis of an active composite unites the structural features of an active material based on silicon composite as an anode in Li-ion battery with high capacity and cyclic reversible charge properties of 3256 mAh g −1 after 200 cycles

Freestanding rGO-SWNT-STN Composite Film as an Anode for Li Ion Batteries with High Energy and Power Densities

Directory of Open Access Journals (Sweden)

Taeseup Song

2015-12-01

Full Text Available Freestanding Si-Ti-Ni alloy particles/reduced graphene oxide/single wall carbon nanotube composites have been prepared as an anode for lithium ion batteries via a simple filtration method. This composite electrode showed a 9% increase in reversible capacity, a two-fold higher cycle retention at 50 cycles and a two-fold higher rate capability at 2 C compared to pristine Si-Ti-Ni (STN alloy electrodes. These improvements were attributed to the suppression of the pulverization of the STN active material by the excellent mechanical properties of the reduced graphene oxide-single wall carbon nanotube networks and the enhanced kinetics associated with both electron and Li ion transport.

Si/C composite lithium-ion battery anodes synthesized from coarse silicon and citric acid through combined ball milling and thermal pyrolysis

International Nuclear Information System (INIS)

Gu Peng; Cai Rui; Zhou Yingke; Shao Zongping

2010-01-01

Silicon and related materials have recently received considerable attention as potential anodes in Li-ion batteries for their high theoretical specific capacities. To overcome the problem of volume variations during the Li insertion/extraction process, in this work, Si/C composites with low carbon content were synthesized from cheap coarse silicon and citric acid by simple ball milling and subsequent thermal treatment. The effects of ball milling time and calcination temperature on the structure, composition and morphology of the composites were systematically investigated by the determination of specific surface area (BET) and particle-size distribution, X-ray diffraction (XRD), O 2 -TPO, and scanning electron microscopy (SEM). The capacity and cycling stability of the composites were systematically evaluated by electrochemical charge/discharge tests. It was found that both the initial capacity and the cycling stability of the composites were dependent on the milling and calcination conditions, and attractive overall electrochemical performance could be obtained by optimizing the synthesis process.

High quality NMP exfoliated graphene nanosheet-SnO2 composite anode material for lithium ion battery.

Science.gov (United States)

Ravikumar, Raman; Gopukumar, Sukumaran

2013-03-21

A graphene nanosheet-SnO(2) (GNS-SnO(2)) composite is prepared using N-methylpyrrolidone as a solvent to exfoliate graphene from graphite bar with the aid of CTAB by single phase co-precipitation method. The synthesized composites has been characterised physically by powder XRD which confirms the formation of the composite tetragonal SnO(2) crystal system with the low intense broad 002 plane for GNS. The sandwiched morphology of GNS-SnO(2) and the formation of nanosized particles (around 20 nm) have been confirmed by SEM and TEM images. The presence of sp(2) carbon in the GNS is clear by the highly intense G than D band in laser Raman spectroscopy analysis; furthermore, a single chemical shift has been observed at 132.14 ppm from solid-state (13)C NMR analysis. The synthesized composite has been electrochemically characterized using charge-discharge and EIS analysis. The capacity retentions at the end of the first 10 cycles is 57% (100 mA g(-1) rate), the second 10 cycles is 77.83% (200 mA g(-1)), and the final 10 cycles (300 mA g(-1)) is 81.5%. Moreover the impedance analysis clearly explains the low resistance pathway for Li(+) insertion after 30 cycles when compared with the initial cycle. This superior characteristic of GNS-SnO(2) composite suggests that it is a promising candidate for lithium ion battery anode.

Performance of lithium alloy/lithium and calcium/lithium anodes in thionyl chloride cells

Energy Technology Data Exchange (ETDEWEB)

Keister, P.; Greenwood, J.M.; Holmes, C.F.; Mead, R.T.

1985-08-01

A laminar composite anode construction comprising an inner metal completely surrounded by Li foil was studied as a means of obtaining an end-of-life indicator in a thionyl chloride cell. Inner metals of Ca, 14-2.9 at.% Ca in Li alloys, and 6.7-2.1 at.% Mg in Li alloys were evaluated. Discharge characteristics of cells using these sandwich anodes as well as cells containing the inner anode material alone were determined. It was concluded that cells made with inner anode materials of Ca and Ca/Li alloys containing more than 7 at.% Ca showed promise as a means of obtaining a reliable end-of-life indication. (orig.).

Solution-Grown Silicon Nanowires for Lithium-Ion Battery Anodes

KAUST Repository

Chan, Candace K.; Patel, Reken N.; O’ Connell, Michael J.; Korgel, Brian A.; Cui, Yi

2010-01-01

Composite electrodes composed of silicon nanowires synthesized using the supercritical fluid-liquid-solid (SFLS) method mixed with amorphous carbon or carbon nanotubes were evaluated as Li-ion battery anodes. Carbon coating of the silicon nanowires

Synthesis and superior anode performances of TiO2-carbon-rGO composites in lithium-ion batteries.

Science.gov (United States)

Ren, Yameng; Zhang, Juan; Liu, Yanyan; Li, Hongbian; Wei, Huijuan; Li, Baojun; Wang, Xiangyu

2012-09-26

In this article, TiO(2)-Carbon-rGO (GCT) three-component composite material has been constructed by anchoring TiO(2) nanoparticles (NPs) encapsulated in carbon shells onto reduced graphene oxide (rGO) sheets. The structure of GCT was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N(2) adsorption-desorption isotherms, and transmission electron microscopy (TEM). This material shows a superior retention as the anode materials in lithium ion battery with a specific discharge capacity of 188 mA h g(-1) in the initial cycle and 158 mA h g(-1) after 100 cycles.

The kinetics of anodic dissolution of rhenium in aqueous electrolyte solutions

International Nuclear Information System (INIS)

Atanasyants, A.G.; Kornienko, V.A.

1986-01-01

The kinetics of anodic rhenium dissolution was investigated by means of potentiodynamic and potentiostatic polarization curves recorded at temperature from 293 to 333 K in different media (NaOH, KOH, NaCl, NaBr, HCl, H 2 SO 4 ) using the rotating disc technique. It is shown that the kinetics of anodic rhenium dissolution and effective activation energy depend not only on the composition and pH value of the solutions but also on the structure of the dissolving rhenium surface. The investigation of the anodic behaviour of the rhenium monocrystal revealed the existence of anisotropy of the monocrystal electrochemical properties. The experimental results point to an important role of adsorption processes in anodic rhenium dissolution. Rhenium dissolution proceeds with formation of intermediate surface adsorption complexes between the metal and the components of the solution

A rationally designed composite of alternating strata of Si nanoparticles and graphene: a high-performance lithium-ion battery anode.

Science.gov (United States)

Sun, Fu; Huang, Kai; Qi, Xiang; Gao, Tian; Liu, Yuping; Zou, Xianghua; Wei, Xiaolin; Zhong, Jianxin

2013-09-21

We have successfully fabricated a free-standing Si-re-G (reduced graphene) alternating stratum structure composite through a repeated process of filtering liquid exfoliated graphene oxide and uniformly dispersed Si solution, followed by the reduction of graphene oxide. The as-prepared free-standing flexible alternating stratum structure composite was directly evaluated as the anode for rechargeable lithium half-cells without adding any polymer binder, conductive additives or using current collectors. The half cells based on this new alternating structure composite exhibit an unexpected capacity of 1500 mA h g(-1) after 100 cycles at 1.35 A g(-1). Our rationally proposed strategy has incorporated the long cycle life of carbon and the high lithium-storage capacity of Si into one entity using the feasible and scalable vacuum filtration technique, rendering this new protocol as a readily applicable means of addressing the practical application challenges associated with the next generation of rechargeable lithium-ion batteries.

Ultrathin molybdenum diselenide nanosheets anchored on multi-walled carbon nanotubes as anode composites for high performance sodium-ion batteries

Science.gov (United States)

Zhang, Zhian; Yang, Xing; Fu, Yun; Du, Ke

2015-11-01

Ultrathin molybdenum diselenide nanosheets are decorated on the surface of multi-walled carbon nanotubes (MWCNT) via a one-step hydrothermal method. Uniform MoSe2 nanosheets are firmly anchored on MWCNT according to the characterizations of scanning electron microscope (SEM), transmission electron microscope (TEM). When evaluated as anodes for sodium storage, the MoSe2@MWCNT composites deliver a reversible specific capacity of 459 mAh g-1 at a current of 200 mA g-1 over 90 cycles, and a specific capacity of 385 mAh g-1 even at a current rate of 2000 mAh g-1, which is better than the MoSe2 nanosheets. The enhanced electrochemical performance of the MoSe2@MWCNT composites can be ascribed to the synergic effects of MoSe2 nanosheets and MWCNT. The high capacity and good rate performance reveal that the MoSe2@MWCNT composites are very promising for applications in sodium-ion batteries.

Electronic properties of electrolyte/anodic alumina junction during porous anodizing

Energy Technology Data Exchange (ETDEWEB)

Vrublevsky, I. [Department of Microelectronics, Belarusian State University of Informatics and Radioelectronics, 6 Brovka Street, Minsk 220013 (Belarus)]. E-mail: nil-4-2@bsuir.edu.by; Jagminas, A. [Institute of Chemistry, A. Gostauto 9, LT-01108 Vilnius (Lithuania); Schreckenbach, J. [Institut fuer Chemie, Technische Universitaet Chemnitz, Chemnitz D-09107 (Germany); InnoMat GmbH, Chemnitz (Germany); Goedel, Werner A. [Institut fuer Chemie, Technische Universitaet Chemnitz, Chemnitz D-09107 (Germany)

2007-03-15

The growth of porous oxide films on aluminum (99.99% purity), formed in 4% phosphoric acid was studied as a function of the anodizing voltage (23-53 V) using a re-anodizing technique and transmission electron microscopy (TEM) study. The chemical dissolution behavior of freshly anodized and annealed at 200 deg. C porous alumina films was studied. The obtained results indicate that porous alumina has n-type semiconductive behavior during anodizing in 4% phosphoric acid. During anodising, up to 39 V in the barrier layer of porous films, one obtains an accumulation layer (the thickness does not exceed 1 nm) where the excess electrons have been injected into the solid producing a downward bending of the conductive and valence band towards the interface. The charge on the surface of anodic oxide is negative and decreases with growing anodizing voltage. At the anodizing voltage of about 39 V, the charge on the surface of anodic oxide equals to zero. Above 39 V, anodic alumina/electrolyte junction injects protons from the electrolyte. These immobile positive charges in the surface layer of oxide together with an ionic layer of hydroxyl ions concentrated near the interface create a field, which produces an upward bending of the bands.

Low voltage aluminium anodes. Optimization of the insert-anode bond

Energy Technology Data Exchange (ETDEWEB)

Le Guyader, Herve; Debout, Valerie; Grolleau, Anne-Marie [DCN Cherbourg, Departement 2EI, Place Bruat, BP 440, 50104 Cherbourg-Octeville (France); Pautasso, Jean-Pierre [DGA/CTA 16 bis, avenue Prieur de la Cote D' Or, 94 114 Arcueil Cedex (France)

2004-07-01

Zinc or Al/Zn/In sacrificial anodes are widely used to protect submerged marine structures from corrosion. Their Open Circuit Potential range from - 1 V vs. Ag/AgCl for Zn anodes to -1.1 V vs. Ag/AgCl for Al/Zn/In. These potentials are sufficiently electronegative as to reduce the threshold for stress corrosion cracking and/or hydrogen embrittlement, KISCC, especially in the presence of high strength alloys. In the 90's, an extensive research programme was initiated by DGA/DCN to implement a new low voltage material. Laboratory and full scale marine tests performed on industrial castings, as previously reported, led to the development of a new patented Al- 0.1%Ga alloy having a working potential of - 0.80 to - 0.83 V vs. Ag/AgCl. This alloy was also evaluated at full scale at the Naval Research Laboratory anode qualification site in Key West, Fl, and gave satisfactory results. Around 500 cylindrical AlGa anodes were then installed on a submerged marine structure replacing the classical zinc anode. A first inspection, carried out after a few months of service, showed that some of the anodes had not operated as expected, which led to further investigations. The examinations performed indicated that the problem was due to a bad metallurgical compatibility between the insert and the sacrificial materials inducing a poor bond between the anode and the plain rod insert. Progressive loss of contact between the anode and the structure to be protected was then induced by penetration of sea water and corrosion at the anode-insert interface. This phenomenon was aggravated by seawater pressure. Additional studies were therefore launched with two aims: (1) find temporary remedies for the anodes already installed on the structure; (2) correct the anode original design and/or manufacturing process to achieve the maximum performance on new anodes lots. This paper describes the various solutions investigated to improve the insert-anode bond: design of the anode, rugosity and

Binders and Hosts for High-Capacity Lithium-ion Battery Anodes

Science.gov (United States)

Dufficy, Martin Kyle

Lithium-ion batteries (LIBs) are universal electrochemical energy storage devices that have revolutionized our mobile society. Nonetheless, societal and technological advances drive consumer demand for LIBs with enhanced electrochemical performance, such as higher charge capacity and longer life, compared to conventional LIBs. One method to enhance LIB performance is to replace graphite, the industry standard anode since commercialization of LIBs in 1991, with high-charge capacity materials. Implementing high-capacity anode materials such as tin, silicon, and manganese vanadates, to LIBs presents challenges; Li-insertion is destructive to anode framework, and increasing capacity increases structural strains that pulverize anode materials and results in a short-cycle life. This thesis reports on various methods to extended the cycle life of high-capacity materials. Most of the work is conducted on nano-sized anode materials to reduce Li and electron transport pathway length (facilitating charge-transfer) and reduce strains from volume expansions (preserving anode structure). The first method involves encapsulating tin particles into a graphene-containing carbon nanofiber (CNF) matrix. The composite-CNF matrix houses tin particles to assume strains from tin-volume expansions and produces favorable surface-electrolyte chemistries for stable charge-discharge cycling. Before tin addition, graphene-containing CNFs are produced and assessed as anode materials for LIBs. Graphene addition to CNFs improves electronic and mechanical properties of CNFs. Furthermore, the 2-D nature of graphene provides Li-binding sites to enhance composite-CNF both first-cycle and high-rate capacities > 150% when compared to CNFs in the absence of graphene. With addition of Sn, we vary loadings and thermal production temperature to elucidate structure-composition relationships of tin and graphene-containing CNF electrodes that lead to increased capacity retention. Of note, electrodes containing

Mesoporous Tin-Based Oxide Nanospheres/Reduced Graphene Composites as Advanced Anodes for Lithium-Ion Half/Full Cells and Sodium-Ion Batteries.

Science.gov (United States)

He, Yanyan; Li, Aihua; Dong, Caifu; Li, Chuanchuan; Xu, Liqiang

2017-10-04

The large volume variations of tin-based oxides hinder their extensive application in the field of lithium-ion batteries (LIBs). In this study, structure design, hybrid fabrication, and carbon-coating approaches have been simultaneously adopted to address these shortcomings. To this end, uniform mesoporous NiO/SnO 2 @rGO, Ni-Sn oxide@rGO, and SnO 2 @rGO nanosphere composites have been selectively fabricated. Among them, the obtained NiO/SnO 2 @rGO composite exhibited a high capacity of 800 mAh g -1 at 1000 mA g -1 after 400 cycles. The electrochemical mechanism of NiO/SnO 2 as an anode for LIBs has been preliminarily investigated by ex situ XRD pattern analysis. Furthermore, an NiO/SnO 2 @rGO-LiCoO 2 lithium-ion full cell showed a high capacity of 467.8 mAh g -1 at 500 mA g -1 after 100 cycles. Notably, the NiO/SnO 2 @rGO composite also showed good performance when investigated as an anode for sodium-ion batteries (SIBs). It is believed that the unique mesoporous nanospherical framework, synergistic effects between the various components, and uniform rGO wrapping of NiO/SnO 2 shorten the Li + ion diffusion pathways, maintain sufficient contact between the active material and the electrolyte, mitigate volume changes, and finally improve the electrical conductivity of the electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical degradation of diuron in chloride medium using DSA® based anodes

International Nuclear Information System (INIS)

Pipi, Angelo R. F.; Aquino Neto, Sidney; Andrade, Adalgisa R. de

2013-01-01

This work presents a study of the electrochemical degradation of the herbicide diuron using Ti/Ru x Ti (1-x) O 2 and Ti/Ir x Ti (1-x) O 2 (x 0.3, 0.5 and 0.7) anodes. The investigation of the degradation was conducted in the presence and in the absence of chloride. The study of the herbicide removal as a function of the current density in the absence of chloride yielded 41 and 49% COD (chemical oxygen demand) removals and 10 and 14% TOC (total organic carbon) removal at 100 mA cm -2 , respectively. By keeping the electrolysis time constant (4 h), Ti/Ru 0.7 Ti 0.3 O 2 anode composition was determined as the most active for removal of diuron and its byproduct. The maximum removal value achieved after 4 h was 58%. Addition of chloride doubled the removal ratio, and 100% COD removal was obtained for Ti/Ru 0.3 Ti 0.7 O 2 . High-performance liquid chromatography (HPLC) analysis confirmed the total removal of the herbicide in chloride medium and indicated the formation of byproducts. The generated byproducts presented as function of the applied current density and the anode composition. Ir-based anodes promoted milder oxidation and furnished more byproducts in aqueous medium. (author)

Electrocnecical behaviour of zirconium during its anodic polarization in nitrate solutions

International Nuclear Information System (INIS)

Stabrovskij, A.I.; Karasev, A.F.

1983-01-01

Electrochemical behaviour of zirconium during its anodic polarization in nitrate solutions is investigated in detail to find the method of its complete dissolution. A study has been made of the influence of varioUs factors: current density electric potential, composition and temperature of the solution, anodic polarization duration on the Zr anodic polarization in nitric acid, on the maximum permissible current density and on the zirconium yield to the solution. The zirconium polarization decreases with an acid concentration and temperature increase and increases with the current density. Iron nitrate additions to nitric acid decrease, while ammonium fluoride additions increase zirconium yield into the solution

High performance anode for advanced Li batteries

Energy Technology Data Exchange (ETDEWEB)

Lake, Carla [Applied Sciences, Inc., Cedarville, OH (United States)

2015-11-02

The overall objective of this Phase I SBIR effort was to advance the manufacturing technology for ASI’s Si-CNF high-performance anode by creating a framework for large volume production and utilization of low-cost Si-coated carbon nanofibers (Si-CNF) for the battery industry. This project explores the use of nano-structured silicon which is deposited on a nano-scale carbon filament to achieve the benefits of high cycle life and high charge capacity without the consequent fading of, or failure in the capacity resulting from stress-induced fracturing of the Si particles and de-coupling from the electrode. ASI’s patented coating process distinguishes itself from others, in that it is highly reproducible, readily scalable and results in a Si-CNF composite structure containing 25-30% silicon, with a compositionally graded interface at the Si-CNF interface that significantly improve cycling stability and enhances adhesion of silicon to the carbon fiber support. In Phase I, the team demonstrated the production of the Si-CNF anode material can successfully be transitioned from a static bench-scale reactor into a fluidized bed reactor. In addition, ASI made significant progress in the development of low cost, quick testing methods which can be performed on silicon coated CNFs as a means of quality control. To date, weight change, density, and cycling performance were the key metrics used to validate the high performance anode material. Under this effort, ASI made strides to establish a quality control protocol for the large volume production of Si-CNFs and has identified several key technical thrusts for future work. Using the results of this Phase I effort as a foundation, ASI has defined a path forward to commercialize and deliver high volume and low-cost production of SI-CNF material for anodes in Li-ion batteries.

Vacuum arc anode phenomena

International Nuclear Information System (INIS)

Miller, H.C.

1976-01-01

A brief review of anode phenomena in vacuum arcs is presented. Discussed in succession are: the transition of the arc into the anode spot mode; the temperature of the anode before, during and after the anode spot forms; and anode ions. Characteristically the anode spot has a temperature of the order of the atmospheric boiling point of the anode material and is a copious source of vapor and energetic ions. The dominant mechanism controlling the transition of the vacuum arc into the anode spot mode appears to depend upon the electrode geometry, the electrode material, and the current waveform of the particular vacuum arc being considered. Either magnetic constriction in the gap plasma or gross anode melting can trigger the transition; indeed, a combination of the two is a common cause of anode spot formation

Use of a Soluble Anode in Electrodeposition of Thick Bismuth Telluride Layers

Science.gov (United States)

Maas, M.; Diliberto, S.; de Vaulx, C.; Azzouz, K.; Boulanger, C.

2014-10-01

Integration of thermoelectric devices within an automotive heat exchanger could enable conversion of lost heat into electrical energy, contributing to improved total output from the engine. For this purpose, synthesis of thick bismuth telluride (Bi2Te3) films is required. Bismuth telluride has been produced by an electrochemical method in nitric acid with a sacrificial bismuth telluride anode as the source of cations. The binary layer grows on the working electrode while the counter-electrode, a Bi2Te3 disk obtained by high frequency melting, is oxidized to BiIII and TeIV. This process leads to auto-regeneration of the solution without modification of its composition. The thickness of films deposited by use of the Bi2Te3 anode was approximately 10 times that without. To demonstrate the utility of a soluble anode in electrochemical deposition, we report characterization of the composition and morphology of the films obtained under different experimental conditions. Perfectly dense and regular Bi2Te3 films (˜400 μm) with low internal stress and uniform composition across the cross-section were prepared. Their thermoelectric properties were assessed.

Electrical transport through single-wall carbon nanotube-anodic aluminum oxide-aluminum heterostructures

International Nuclear Information System (INIS)

Kukkola, Jarmo; Rautio, Aatto; Sala, Giovanni; Pino, Flavio; Toth, Geza; Leino, Anne-Riikka; Maeklin, Jani; Jantunen, Heli; Uusimaeki, Antti; Kordas, Krisztian; Gracia, Eduardo; Terrones, Mauricio; Shchukarev, Andrey; Mikkola, Jyri-Pekka

2010-01-01

Aluminum foils were anodized in sulfuric acid solution to form thick porous anodic aluminum oxide (AAO) films of thickness ∼6 μm. Electrodes of carboxyl-functionalized single-wall carbon nanotube (SWCNT) thin films were inkjet printed on the anodic oxide layer and the electrical characteristics of the as-obtained SWCNT-AAO-Al structures were studied. Nonlinear current-voltage transport and strong temperature dependence of conduction through the structure was measured. The microstructure and chemical composition of the anodic oxide layer was analyzed using transmission and scanning electron microscopy as well as x-ray photoelectron spectroscopy. Schottky emission at the SWCNT-AAO and AAO-Al interfaces allowed by impurity states in the anodic aluminum oxide film together with ionic surface conduction on the pore walls of AAO gives a reasonable explanation for the measured electrical conduction. Calcined AAO is proposed as a dielectric material for SWCNT-field effect transistors.

Solid-solution-like ZnO/C composites as excellent anode materials for lithium ion batteries

International Nuclear Information System (INIS)

Zhang, Guanhua; Zhang, Hang; Zhang, Xiang; Zeng, Wei; Su, Qingmei; Du, Gaohui; Duan, Huigao

2015-01-01

Exploring advanced anode materials to maximize the capacity of lithium ion batteries has been an active research area for decades. Constructing composites materials has been proved to be one of the most effective methods to achieve higher capacity due to the synergistic effect. In this work, we proposed and demonstrated a concept of solid-solution-like ZnO/C composites to approach the largest possible synergistic effect by introducing the most interfaces and minimizing the pulverization. The solid-solution-like ZnO/C electrode could achieve a high reversible capacity of 813.3 mAh g −1 at a current density of 100 mA g −1 after 100 cycles with a decrease rate of only 0.4% per cycle. Moreover, the discharge capacity still maintained 53.5% of the original value even when the current density increased to 40 times as much as the original, showing a distinguished rate performance. In addition, such solid-solution-like nanofibers can be easily prepared because of their compatibility with the existing industrial PAN-based spinning process. This may pave the way to mass produce lithium ion batteries with significantly enhanced performance using existing low-cost commercial facilities and recipes.

Improving the Tribological Properties of Spark-Anodized Titanium by Magnetron Sputtered Diamond-Like Carbon

OpenAIRE

Zhaoxiang Chen; Xipeng Ren; Limei Ren; Tengchao Wang; Xiaowen Qi; Yulin Yang

2018-01-01

Spark-anodization of titanium can produce adherent and wear-resistant TiO2 film on the surface, but the spark-anodized titanium has lots of surface micro-pores, resulting in an unstable and high friction coefficient against many counterparts. In this study, the diamond-like carbon (DLC) was introduced into the micro-pores of spark-anodized titanium by the magnetron sputtering technique and a TiO2/DLC composite coating was fabricated. The microstructure and tribological properties of TiO2/DLC ...

Properties of nanostructures obtained by anodization of aluminum in phosphoric acid at moderate potentials

Energy Technology Data Exchange (ETDEWEB)

Zaraska, L; Jaskula, M [Department of Physical Chemistry and Electrochemistry, Jagiellonian University, Ingardena 3, 30060 Krakow (Poland); Sulka, G D, E-mail: sulka@chemia.uj.edu.pl

2009-01-01

The influence of the process duration, anodizing potential and methanol addition on the structural features of porous anodic alumina formed in a 0.3 M H{sub 3}PO{sub 4} solutions by twostep self-organized anodizing was investigated for potentials ranging from 100 to 170 V. The structural features of porous structures including pore diameter and interpore distance were evaluated from FE-SEM top-view images for samples anodized in the presence and absence of methanol. For the highest studied anodizing time and methanol volume fraction, an excellent agreement between experimental values of the interpore distance and theoretical predictions was observed. The pore arrangement regularity was analyzed for various electrolyte compositions and anodizing potentials. It was found that the regularity ratio of porous alumina increases linearly with increasing anodizing potential and time. The addition of methanol improves the quality of nanostructures and especially better uniformity of pore sizes is observed in the presence of the highest studied methanol content.

Properties of nanostructures obtained by anodization of aluminum in phosphoric acid at moderate potentials

Science.gov (United States)

Zaraska, L.; Sulka, G. D.; Jaskuła, M.

2009-01-01

The influence of the process duration, anodizing potential and methanol addition on the structural features of porous anodic alumina formed in a 0.3 M H3PO4 solutions by twostep self-organized anodizing was investigated for potentials ranging from 100 to 170 V. The structural features of porous structures including pore diameter and interpore distance were evaluated from FE-SEM top-view images for samples anodized in the presence and absence of methanol. For the highest studied anodizing time and methanol volume fraction, an excellent agreement between experimental values of the interpore distance and theoretical predictions was observed. The pore arrangement regularity was analyzed for various electrolyte compositions and anodizing potentials. It was found that the regularity ratio of porous alumina increases linearly with increasing anodizing potential and time. The addition of methanol improves the quality of nanostructures and especially better uniformity of pore sizes is observed in the presence of the highest studied methanol content.

ORDERED POROUS ANODIC ALUMINUM OXIDE FILMS MADE BY TWO-STEP ANODIZATION

OpenAIRE

HANSONG XUE; HUAJI LI; YU YI; HUIFANG HU

2007-01-01

Porous Anodic Aluminum Oxide (AAO) films were prepared by two-step anodizing in sulfuric and oxalic acid solutions and observed by transmission electron microscope (TEM) and X-ray diffraction. The results show that the form of AAO film is affected by the varieties and concentrations of electrolyte, anodizing voltage, and the anodizing time; the formation and evolution processes of the AAO film are relative with the anodizing voltage severely, and the appropriate voltage is helpful to the orde...

Nitrogen-Doped Carbon for Red Phosphorous Based Anode Materials for Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Jiaoyang Li

2018-01-01

Full Text Available Serving as conductive matrix and stress buffer, the carbon matrix plays a pivotal role in enabling red phosphorus to be a promising anode material for high capacity lithium ion batteries and sodium ion batteries. In this paper, nitrogen-doping is proved to effective enhance the interface interaction between carbon and red phosphorus. In detail, the adsorption energy between phosphorus atoms and oxygen-containing functional groups on the carbon is significantly reduced by nitrogen doping, as verified by X-ray photoelectron spectroscopy. The adsorption mechanisms are further revealed on the basis of DFT (the first density functional theory calculations. The RPNC (red phosphorus/nitrogen-doped carbon composite material shows higher cycling stability and higher capacity than that of RPC (red phosphorus/carbon composite anode. After 100 cycles, the RPNC still keeps discharge capacity of 1453 mAh g−1 at the current density of 300 mA g−1 (the discharge capacity of RPC after 100 cycles is 1348 mAh g−1. Even at 1200 mA g−1, the RPNC composite still delivers a capacity of 1178 mAh g−1. This work provides insight information about the interface interactions between composite materials, as well as new technology develops high performance phosphorus based anode materials.

Characterization of Raw and Decopperized Anode Slimes from a Chilean Refinery

Science.gov (United States)

Melo Aguilera, Evelyn; Hernández Vera, María Cecilia; Viñals, Joan; Graber Seguel, Teófilo

2016-04-01

This work characterizes raw and decopperized slimes, with the objective of identifying the phases in these two sub-products. The main phases in copper anodes are metallic copper, including CuO, which are present in free form or associated with the presence of copper selenide or tellurides (Cu2(Se,Te)) and several Cu-Pb-Sb-As-Bi oxides. During electrorefining, the impurities in the anode release and are not deposited in the cathode, part of them dissolving and concentrated in the electrolyte, and others form a raw anode slime that contains Au, Ag, Cu, As, Se, Te and PGM, depending on the composition of the anode. There are several recovery processes, most of which involve acid leaching in the first step to dissolve copper, whose product is decopperized anode slime. SEM analysis revealed that the mineralogical species present in the raw anode slime under study were mainly eucarite (CuAgSe), naumannite (Ag2Se), antimony arsenate (SbAsO4), and lead sulfate (PbSO4). In the case of decopperized slime, the particles were mainly composed of SbAsO4 (crystalline appearance), non-stoichiometric silver selenide (Ag(2- x)Se), and chlorargyrite (AgCl).

Physico-Chemical and Electrochemical Properties of Nanoparticulate NiO/C Composites for High Performance Lithium and Sodium Ion Battery Anodes

Directory of Open Access Journals (Sweden)

Amaia Iturrondobeitia

2017-12-01

Full Text Available Nanoparticulate NiO and NiO/C composites with different carbon proportions have been prepared for anode application in lithium and sodium ion batteries. Structural characterization demonstrated the presence of metallic Ni in the composites. Morphological study revealed that the NiO and Ni nanoparticles were well dispersed in the matrix of amorphous carbon. The electrochemical study showed that the lithium ion batteries (LIBs, containing composites with carbon, have promising electrochemical performances, delivering specific discharge capacities of 550 mAh/g after operating for 100 cycles at 1C. These excellent results could be explained by the homogeneity of particle size and structure, as well as the uniform distribution of NiO/Ni nanoparticles in the in situ generated amorphous carbon matrix. On the other hand, the sodium ion battery (NIB with the NiO/C composite revealed a poor cycling stability. Post-mortem analyses revealed that this fact could be ascribed to the absence of a stable Solid Electrolyte Interface (SEI or passivation layer upon cycling.

Diversity and function of the microbial community on anodes of sediment microbial fuel cells fueled by root exudates

Energy Technology Data Exchange (ETDEWEB)

Cabezas da Rosa, Angela

2010-11-26

Anode microbial communities are essential for current production in microbial fuel cells. Anode reducing bacteria are capable of using the anode as final electron acceptor in their respiratory chain. The electrons delivered to the anode travel through a circuit to the cathode where they reduce oxygen to water generating an electric current. A novel type of sediment microbial fuel cell (SMFC) harvest energy from photosynthetically derived compounds released through the roots. Nothing is known about anode microbial communities of this type of microbial fuel cell. This work consists of three parts. The first part focuses on the study of bacterial and archaeal community compositions on anodes of SMFCs fueled by rice root exudates. By using terminal restriction fragment length polymorphism (T-RFLP), a profiling technique, and cloning / sequencing of 16S rRNA, we determined that the support type used for the plant (vermiculite, potting soil or rice field soil) is an important factor determining the composition of the microbial community. Finally, by comparing microbial communities of current producing anodes and non-current producing controls we determined that Desulfobulbus- and Geobacter-related populations were probably most important for current production in potting soil and rice field soil SMFCs, respectively. However, {delta}-proteobacterial Anaeromyxobacter spp., unclassified {delta}-proteobacteria and Anaerolineae were also part of the anode biofilm in rice field soil SMFCs and these populations might also play a role in current production. Moreover, distinct clusters of Geobacter and Anaeromyxobacter populations were stimulated by rice root exudates. Regarding Archaea, uncultured Euryarchaea were abundant on anodes of potting soil SMFCs indicating a potential role in current production. In both, rice field soil and potting soil SMFCs, a decrease of Methanosaeta, an acetotrophic methanogen, was detected on current producing anodes. In the second part we focused

Synthesis and optimization of tin dioxide/functionalized multi-walled carbon nanotube composites as anode in lithium-ion battery

Energy Technology Data Exchange (ETDEWEB)

Xu, Xiao-Bing; Geng, Hong-Zhang, E-mail: genghz@tjpu.edu.cn; Meng, Yan; Ding, Er-Xiong; Wang, Yan; Zhang, Ze-Chen; Wang, Wen-Yi

2015-03-01

In this paper, nanocomposite electrodes for rechargeable Lithium-ion battery composed of tin dioxide (SnO{sub 2}) and multi-walled carbon nanotubes (MWCNTs) were prepared using the chemical deposition method with a subsequent sintering process. The as-prepared hybrids were characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The results showed that the size of pure SnO{sub 2} particles was ∼5 nm and hybrids presented a uniform dispersion of SnO{sub 2} nanoparticles on the surfaces of the MWCNTs. The electrochemical properties of the composites were researched through a cyclic voltammetry and a galvanostatic charge–discharge test. It was found that the electrochemical performance of the composite was strongly dependent on the content of MWCNTs in the composites. The SnO{sub 2}/MWCNT composite with 18.40 wt% MWCNTs gave the best performance, exhibiting a relatively higher reversible capacity of 475 mAh g{sup −1} and an extended capacity retention of 65% even after 30 cycles at a current density of 78.2 mA g{sup −1}. - Highlights: • SnO{sub 2}/MWCNT nanocomposites were prepared using chemical deposition method. • SnO{sub 2} nanoparticles presented a uniformly dispersion on the surfaces of MWCNTs. • SnO{sub 2}/MWCNT composite anode exhibited high reversible capacity for rechargeable Li-ion battery.

Synthesis and optimization of tin dioxide/functionalized multi-walled carbon nanotube composites as anode in lithium-ion battery

International Nuclear Information System (INIS)

Xu, Xiao-Bing; Geng, Hong-Zhang; Meng, Yan; Ding, Er-Xiong; Wang, Yan; Zhang, Ze-Chen; Wang, Wen-Yi

2015-01-01

In this paper, nanocomposite electrodes for rechargeable Lithium-ion battery composed of tin dioxide (SnO 2 ) and multi-walled carbon nanotubes (MWCNTs) were prepared using the chemical deposition method with a subsequent sintering process. The as-prepared hybrids were characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The results showed that the size of pure SnO 2 particles was ∼5 nm and hybrids presented a uniform dispersion of SnO 2 nanoparticles on the surfaces of the MWCNTs. The electrochemical properties of the composites were researched through a cyclic voltammetry and a galvanostatic charge–discharge test. It was found that the electrochemical performance of the composite was strongly dependent on the content of MWCNTs in the composites. The SnO 2 /MWCNT composite with 18.40 wt% MWCNTs gave the best performance, exhibiting a relatively higher reversible capacity of 475 mAh g −1 and an extended capacity retention of 65% even after 30 cycles at a current density of 78.2 mA g −1 . - Highlights: • SnO 2 /MWCNT nanocomposites were prepared using chemical deposition method. • SnO 2 nanoparticles presented a uniformly dispersion on the surfaces of MWCNTs. • SnO 2 /MWCNT composite anode exhibited high reversible capacity for rechargeable Li-ion battery

Anodic polarization of carbon graphite electrodes in chloride fluoride melts zirconium containing

International Nuclear Information System (INIS)

Lyapustin, A.A.; Kanashin, Yu.P.; Nichkov, I.F.; Smyshlyaev, V.Yu.

1985-01-01

Polarization of carbon graphite anodes in zircorium containing chloride fluoride melts of the KCl-K 2 ZrF 6 -KF composition at molar ratios [F]:[Zr] being equal to 6, 12, 18, 24, 30 has been studied. K 2 ZrF 6 concentration constitutes 25; 18.9; 15.2; 12.7; 11.8% (by mass), correspondingly. Vitreous carbon (VC-2500), high purity graphite and graphite EhG-0 have been used as anodic materials. Anodic polarization curves have been obtained under electrotype steady-state conditions at 973, 1023, 1073 K. Influence of concentration of fluorine ions in melt on polarization of carbon graphite anodes is shown. Content growth of fluorine ions in melt leads to shift of steady-state anode potentials to their negative values regardless a graphite mark. The most con siderable potential shift on 0.5 V takes plase at molar ratio [F]:[Zr] increasing from 6 to 12. Temperature increase, as measurements showed, doesn't influence greatly on polarization curve shape

The effect of sulfuric acid on pore initiation in anodic alumina formed in oxalic acid

Directory of Open Access Journals (Sweden)

Behnam Hafezi

2014-07-01

Full Text Available In this work, a tracer study on pore initiation in anodic alumina in oxalic acid was performed. Effects of some experimental parameters such as applied electrical potential, electrolyte composition and heat pretreatment were evaluated. Electrochemical and morphological experiments were performed using potentiostatic anodizing and scanning electron microscopy (SEM techniques, respectively. Effect of electrolyte composition on current density was discussed. In various electrical potentials, electrolyte composition had different effects on current density. Addition of sulfuric acid into oxalic acid increased porosity. Also, distribution of pore size and pore diameter were influenced by presence of sulfuric acid. Effect of electrolyte composition on the morphology of aluminum surface layer depended on the electric potential. Current density and porosity of aluminum surface layer was decreased by heat pretreatment.

The impact of steam and current density on carbon formation from biomass gasification tar on Ni/YSZ, and Ni/CGO solid oxide fuel cell anodes

Science.gov (United States)

Mermelstein, Joshua; Millan, Marcos; Brandon, Nigel

The combination of solid oxide fuel cells (SOFCs) and biomass gasification has the potential to become an attractive technology for the production of clean renewable energy. However the impact of tars, formed during biomass gasification, on the performance and durability of SOFC anodes has not been well established experimentally. This paper reports an experimental study on the mitigation of carbon formation arising from the exposure of the commonly used Ni/YSZ (yttria stabilized zirconia) and Ni/CGO (gadolinium-doped ceria) SOFC anodes to biomass gasification tars. Carbon formation and cell degradation was reduced through means of steam reforming of the tar over the nickel anode, and partial oxidation of benzene model tar via the transport of oxygen ions to the anode while operating the fuel cell under load. Thermodynamic calculations suggest that a threshold current density of 365 mA cm -2 was required to suppress carbon formation in dry conditions, which was consistent with the results of experiments conducted in this study. The importance of both anode microstructure and composition towards carbon deposition was seen in the comparison of Ni/YSZ and Ni/CGO anodes exposed to the biomass gasification tar. Under steam concentrations greater than the thermodynamic threshold for carbon deposition, Ni/YSZ anodes still exhibited cell degradation, as shown by increased polarization resistances, and carbon formation was seen using SEM imaging. Ni/CGO anodes were found to be more resilient to carbon formation than Ni/YSZ anodes, and displayed increased performance after each subsequent exposure to tar, likely due to continued reforming of condensed tar on the anode.

Pd-Pt loaded graphene aerogel on nickel foam composite as binder-free anode for a direct glucose fuel cell unit

Science.gov (United States)

Tsang, Chi Him A.; Leung, D. Y. C.

2017-09-01

Fabrication of electrocatalyst for direct glucose fuel cell (DGFC) operation involves destructive preparation methods with the use of stabilizer like binder, which may cause activity depreciation. Binder-free electrocatalytic electrode becomes a possible solution to the above problem. Binder-free bimetallic Pd-Pt loaded graphene aerogel on nickel foam plates with different Pd/Pt ratios (1:2.32, 1:1.62, and 1:0.98) are successfully fabricated through a green one-step mild reduction process producing a Pd-Pt/GO/nickel form plate (NFP) composite. Anode with the binder-free electrocatalysts exhibit a strong activity in a batch type DGFC unit under room temperature. The effects of glucose and KOH concentrations, and the Pd/Pt ratios of the electrocatalyst on the DGFC performance are also studied. Maximum power density output of 1.25 mW cm-2 is recorded with 0.5 M glucose/3 M KOH as the anodic fuel, and Pd1Pt0.98/GA/NFP as catalyst, which is the highest obtained so far among other types of electrocatalyst.

Anodic dissolution of samarium in acetonitrile solution of acetylacetone

International Nuclear Information System (INIS)

Kostyuk, N.N.; Dik, T.A.; Trebnikov, A.G.; Shirokij, V.L.

2003-01-01

Electrochemical dissolution of metal samarium in acetonitrile medium in the presence of 0.1 M tetraethylammoniumbromide and 0.9 M acetylacetone (HAA) in argon atmosphere under a voltage of 3 V was considered for studying feasibility of electrochemical synthesis of samarium β-diketonates. Using IR and mass spectrometry, thermal and elementary analyses it was ascertained that, depending on cathode and anode areas ratio, anodic dissolution of samarium can give rise to formation of complexes of bi- and trivalent samarium featuring the composition Sm 4 (AA) 8 · 3HAA, Sm(AA) 3 · HAA and Sm(AA) 3 · 4HAA [ru

Solvent transfer of graphene oxide for synthesis of tin mono-sulfide graphene composite and application as anode of lithium-ion battery

Energy Technology Data Exchange (ETDEWEB)

Tripathi, Alok M., E-mail: alokmani@iitb.ac.in; Mitra, Sagar

2016-11-15

Graphical abstract: Destabilization of graphene oxide colloid and SnS graphene composite preparation for lithium-ion battery. - Abstract: Tin mono sulfide (SnS) graphene composite has been synthesized for anode of lithium-ion battery. For synthesis of composite, graphene oxide (GO)-water (H{sub 2}O) colloid has been destabilized and ensured the complete transfer of graphene oxide into another organic solvent N, N-dimethyl formamide (DMF). Mechanism for the destabilization of GO-H{sub 2}O colloid is established. Surface to surface attachment of SnS on graphene sheet is achieved by solvothermal solution phase assembly of graphene sheets and SnS nanoparticles in DMF solvent. Graphene plays role in nanoparticle formation in composite. Such confined composite has been cycled reversibly at current rate of 160 mA g{sup −1}, in voltage region of 0.01–2.5 V and exhibit a superior discharge capacity of 630 mAh g{sup −1} after 50th cycle. Ex situ TEM analysis of used electrode reveal that the SnS nanoparticle-graphene composite with CMC binder perform better due to proper shape retention of electroactive materials during electrochemical cycling.

Solvent transfer of graphene oxide for synthesis of tin mono-sulfide graphene composite and application as anode of lithium-ion battery

International Nuclear Information System (INIS)

Tripathi, Alok M.; Mitra, Sagar

2016-01-01

Graphical abstract: Destabilization of graphene oxide colloid and SnS graphene composite preparation for lithium-ion battery. - Abstract: Tin mono sulfide (SnS) graphene composite has been synthesized for anode of lithium-ion battery. For synthesis of composite, graphene oxide (GO)-water (H_2O) colloid has been destabilized and ensured the complete transfer of graphene oxide into another organic solvent N, N-dimethyl formamide (DMF). Mechanism for the destabilization of GO-H_2O colloid is established. Surface to surface attachment of SnS on graphene sheet is achieved by solvothermal solution phase assembly of graphene sheets and SnS nanoparticles in DMF solvent. Graphene plays role in nanoparticle formation in composite. Such confined composite has been cycled reversibly at current rate of 160 mA g"−"1, in voltage region of 0.01–2.5 V and exhibit a superior discharge capacity of 630 mAh g"−"1 after 50th cycle. Ex situ TEM analysis of used electrode reveal that the SnS nanoparticle-graphene composite with CMC binder perform better due to proper shape retention of electroactive materials during electrochemical cycling.

Nano-Sized Structurally Disordered Metal Oxide Composite Aerogels as High-Power Anodes in Hybrid Supercapacitors.

Science.gov (United States)

Huang, Haijian; Wang, Xing; Tervoort, Elena; Zeng, Guobo; Liu, Tian; Chen, Xi; Sologubenko, Alla; Niederberger, Markus

2018-03-27

A general method for preparing nano-sized metal oxide nanoparticles with highly disordered crystal structure and their processing into stable aqueous dispersions is presented. With these nanoparticles as building blocks, a series of nanoparticles@reduced graphene oxide (rGO) composite aerogels are fabricated and directly used as high-power anodes for lithium-ion hybrid supercapacitors (Li-HSCs). To clarify the effect of the degree of disorder, control samples of crystalline nanoparticles with similar particle size are prepared. The results indicate that the structurally disordered samples show a significantly enhanced electrochemical performance compared to the crystalline counterparts. In particular, structurally disordered Ni x Fe y O z @rGO delivers a capacity of 388 mAh g -1 at 5 A g -1 , which is 6 times that of the crystalline sample. Disordered Ni x Fe y O z @rGO is taken as an example to study the reasons for the enhanced performance. Compared with the crystalline sample, density functional theory calculations reveal a smaller volume expansion during Li + insertion for the structurally disordered Ni x Fe y O z nanoparticles, and they are found to exhibit larger pseudocapacitive effects. Combined with an activated carbon (AC) cathode, full-cell tests of the lithium-ion hybrid supercapacitors are performed, demonstrating that the structurally disordered metal oxide nanoparticles@rGO||AC hybrid systems deliver high energy and power densities within the voltage range of 1.0-4.0 V. These results indicate that structurally disordered nanomaterials might be interesting candidates for exploring high-power anodes for Li-HSCs.

Impact de la preparation des anodes crues et des conditions de cuisson sur la fissuration dans des anodes denses

Science.gov (United States)

Amrani, Salah

fabriquees industriellement. Cette technique a consiste a determiner le profil des differentes proprietes physiques. En effet, la methode basee sur la mesure de la distribution de la resistivite electrique sur la totalite de l'echantillon est la technique qui a ete utilisee pour localiser la fissuration et les macro-pores. La microscopie optique et l'analyse d'image ont, quant a elles, permis de caracteriser les zones fissurees tout en determinant la structure des echantillons analyses a l'echelle microscopique. D'autres tests ont ete menes, et ils ont consiste a etudier des echantillons cylindriques d'anodes de 50 mm de diametre et de 130 mm de longueur. Ces derniers ont ete cuits dans un four a UQAC a differents taux de chauffage dans le but de pouvoir determiner l'influence des parametres de cuisson sur la formation de la fissuration dans ce genre de carottes. La caracterisation des echantillons d'anodes cuites a ete faite a l'aide de la microscopie electronique a balayage et de l'ultrason. La derniere partie des travaux realises a l'UQAC contient une etude sur la caracterisation des anodes fabriquees au laboratoire sous differentes conditions d'operation. L'evolution de la qualite de ces anodes a ete faite par l'utilisation de plusieurs techniques. L'evolution de la temperature de refroidissement des anodes crues de laboratoire a ete mesuree; et un modele mathematique a ete developpe et valide avec les donnees experimentales. Cela a pour objectif d'estimer la vitesse de refroidissement ainsi que le stress thermique. Toutes les anodes fabriquees ont ete caracterisees avant la cuisson par la determination de certaines proprietes physiques (resistivite electrique, densite apparente, densite optique et pourcentage de defauts). La tomographie et la distribution de la resistivite electrique, qui sont des techniques non destructives, ont ete employees pour evaluer les defauts internes des anodes. Pendant la cuisson des anodes de laboratoire, l'evolution de la resistivite

Plant-scale anodic dissolution of unirradiated IFR fuel pins

International Nuclear Information System (INIS)

Gay, E.C.; Tomczuk, Z.; Miller, W.E.

1993-01-01

This report discusses anodic dissolution which is a major operation in the pyrometallurgical process for recycling spent metal fuels from the Integral Fast Reactor (IFR), an advanced reactor design developed at Argonne National Laboratory. This process involves electrorefining the heavy metals (uranium and plutonium) from chopped, steel-clad fuel segments. The heavy metals are electrotransported from anodic dissolution baskets to solid and liquid cathodes in a molten salt electrolyte (LiCl-KCI) at 500 degrees C. Uranium is recovered on a solid cathode mandrel, while a uranium-plutonium mixture is recovered in a liquid cadmium cathode. The anode configuration consists of four baskets mounted on an anode shaft. These baskets provide parallel circuits in the electrolyte and salt flow through the chopped fuelbed as the baskets are rotated. The baskets for the engineering-scale tests were sized to contain up to 2.5 kg of heavy metal. Anodic dissolution of 10 kg batches of chopped, steel-clad simulated tuel (U-10% Zr and U-Zr-Fs alloy) was demonstrated

Silicon/Wolfram Carbide@Graphene composite: enhancing conductivity and structure stability in amorphous-silicon for high lithium storage performance

International Nuclear Information System (INIS)

Sun, Wei; Hu, Renzong; Liu, Hui; Zhang, Hanying; Liu, Jiangwen; Yang, Lichun; Wang, Haihui; Zhu, Min

2016-01-01

Highlights: • Two-step ball milling was used to produce an amorphous-Si/WC@Graphene(SW@G) composite. • Concrete-like core-shell structure with high stability was designed. • Multiscale WC particle strengthen the inside structure. • Graphene coating outside much enhanced the cycling stability and conductivity. • The SW@G anode exhibited long cycle life and superior volumetric capacity. - Abstract: Improving the electron conductivity and lithiated structure stability for Si anodes can result in high stable capacity in cells. A Silicon/Wolfram Carbide@Graphene (SW@G) composite anode is designed and produced by a simple two-step ball milling the mixture of coarse-grained Si with good conductive wolfram carbide (WC) and graphite. The SW@G composite consists of multiple-scale WC particles, which are uniformly distributed in amorphous Si matrices, and wrapped by graphene nanosheets (GNs) on the outside. Owing to the unique concrete-like core-shell structure, the wrapping of GNs on the Si improves the conductivity and structural stability of the composite. The inner WC particles which tightly connect the Si and graphene act as the cornerstone to resist large volumetric expansion of Si during charge/discharge, and in particular serve as the high-speed channels of electrons as well as provide more interface paths for Li + to accelerate their transfer inside the Si. These contribute to the excellent electrochemical properties of SW@G composite anode, including high volumetric capacity (three times higher than that of graphite), superior rate capability, and long-life stable cycleability. The synthetic method developed in this work paves the way for large-scale manufacturing of high performance Li storage anodes using commercially available materials and technologies.

Electrochemical properties of SnO2/carbon composite materials as anode material for lithium-ion batteries

International Nuclear Information System (INIS)

Wang Jie; Zhao Hailei; Liu Xiaotong; Wang Jing; Wang Chunmei

2011-01-01

Highlights: → SnO 2 /carbon powders with a cauliflower-like particle structure were synthesized. → Post-annealing can improve the electrochemical properties of SnO 2 /C composite. → The 500 deg. C-annealed SnO 2 /C shows the best electrochemical performance. → The lithium ion diffusion coefficients of the SnO 2 /C electrodes were calculated. - Abstract: SnO 2 /carbon composite anode materials were synthesized from SnCl 4 .5H 2 O and sucrose via a hydrothermal route and a post heat-treatment. The synthesized spherical SnO 2 /carbon powders show a cauliflower-like micro-sized structure. High annealing temperature results in partial reduction of SnO 2 . Metallic Sn starts to emerge at 500 deg. C. High Sn content in SnO 2 /carbon composite is favorable for the increase of initial coulombic efficiency but not for the cycling stability. The SnO 2 /carbon annealed at 500 deg. C exhibits high specific capacity (∼400 mAh g -1 ), stable cycling performance and good rate capability. The generation of Li 2 O in the first lithiation process can prevent the aggregation of active Sn, while the carbon component can buffer the big volume change caused by lithiation/delithiation of active Sn. Both of them make contribution to the better cycle stability.

Three-Dimensional Carbon Nanotube−Textile Anode for High-Performance Microbial Fuel Cells

KAUST Repository

Xie, Xing; Hu, Liangbing; Pasta, Mauro; Wells, George F.; Kong, Desheng; Criddle, Craig S.; Cui, Yi

2011-01-01

Microbial fuel cells (MFCs) harness the metabolism of microorganisms, converting chemical energy into electrical energy. Anode performance is an important factor limiting the power density of MFCs for practical application. Improving the anode design is thus important for enhancing the MFC performance, but only a little development has been reported. Here, we describe a biocompatible, highly conductive, two-scale porous anode fabricated from a carbon nanotube-textile (CNT-textile) composite for high-performance MFCs. The macroscale porous structure of the intertwined CNT-textile fibers creates an open 3D space for efficient substrate transport and internal colonization by a diverse microflora, resulting in a 10-fold-larger anolyte-biofilm-anode interfacial area than the projective surface area of the CNT-textile. The conformally coated microscale porous CNT layer displays strong interaction with the microbial biofilm, facilitating electron transfer from exoelectrogens to the CNT-textile anode. An MFC equipped with a CNT-textile anode has a 10-fold-lower charge-transfer resistance and achieves considerably better performance than one equipped with a traditional carbon cloth anode: the maximum current density is 157% higher, the maximum power density is 68% higher, and the energy recovery is 141% greater. © 2011 American Chemical Society.

Three-Dimensional Carbon Nanotube−Textile Anode for High-Performance Microbial Fuel Cells

KAUST Repository

Xie, Xing

2011-01-12

Microbial fuel cells (MFCs) harness the metabolism of microorganisms, converting chemical energy into electrical energy. Anode performance is an important factor limiting the power density of MFCs for practical application. Improving the anode design is thus important for enhancing the MFC performance, but only a little development has been reported. Here, we describe a biocompatible, highly conductive, two-scale porous anode fabricated from a carbon nanotube-textile (CNT-textile) composite for high-performance MFCs. The macroscale porous structure of the intertwined CNT-textile fibers creates an open 3D space for efficient substrate transport and internal colonization by a diverse microflora, resulting in a 10-fold-larger anolyte-biofilm-anode interfacial area than the projective surface area of the CNT-textile. The conformally coated microscale porous CNT layer displays strong interaction with the microbial biofilm, facilitating electron transfer from exoelectrogens to the CNT-textile anode. An MFC equipped with a CNT-textile anode has a 10-fold-lower charge-transfer resistance and achieves considerably better performance than one equipped with a traditional carbon cloth anode: the maximum current density is 157% higher, the maximum power density is 68% higher, and the energy recovery is 141% greater. © 2011 American Chemical Society.

Defect-rich TiO2-δ nanocrystals confined in a mooncake-shaped porous carbon matrix as an advanced Na ion battery anode

Science.gov (United States)

He, Hanna; Zhang, Qi; Wang, Haiyan; Zhang, Hehe; Li, Jiadong; Peng, Zhiguang; Tang, Yougen; Shao, Minhua

2017-06-01

Inferior electronic conductivity and sluggish sodium ion diffusion are still two big challenges for TiO2 anode material for Na ion batteries (SIBs). Herein, we synthesize TiO2/C composites by the pyrolysis of MIL-125(Ti) precursor and successfully introduce defects to TiO2/C composite by a simple magnesium reduction. The as-prepared defect-rich TiO2-δ/C composite shows mooncake-shaped morphology consisting of TiO2-δ nanocrystals with an average particle size of 5 nm well dispersed in the carbon matrix. When used as a SIBs anode, the defect-rich TiO2-δ/C composite exhibits a high reversible capacity of 330.2 mAh g-1 at 50 mA g-1 at the voltage range of 0.001-3.0 V and long-term cycling stability with negligible decay after 5000 cycles. Compared with other four TiO2/C samples, the electrochemical performance of defect-rich TiO2-δ/C is highly improved, which may benefit from the enhanced electronic/ionic conductivities owing to the defect-rich features, high surface area rendering shortened electronic and ionic diffusion path, and the suppress of the TiO2 crystal aggregation during sodiation and desodiation process by the carbon matrix.

Bending-Tolerant Anodes for Lithium-Metal Batteries.

Science.gov (United States)

Wang, Aoxuan; Tang, Shan; Kong, Debin; Liu, Shan; Chiou, Kevin; Zhi, Linjie; Huang, Jiaxing; Xia, Yong-Yao; Luo, Jiayan

2018-01-01

Bendable energy-storage systems with high energy density are demanded for conformal electronics. Lithium-metal batteries including lithium-sulfur and lithium-oxygen cells have much higher theoretical energy density than lithium-ion batteries. Reckoned as the ideal anode, however, Li has many challenges when directly used, especially its tendency to form dendrite. Under bending conditions, the Li-dendrite growth can be further aggravated due to bending-induced local plastic deformation and Li-filaments pulverization. Here, the Li-metal anodes are made bending tolerant by integrating Li into bendable scaffolds such as reduced graphene oxide (r-GO) films. In the composites, the bending stress is largely dissipated by the scaffolds. The scaffolds have increased available surface for homogeneous Li plating and minimize volume fluctuation of Li electrodes during cycling. Significantly improved cycling performance under bending conditions is achieved. With the bending-tolerant r-GO/Li-metal anode, bendable lithium-sulfur and lithium-oxygen batteries with long cycling stability are realized. A bendable integrated solar cell-battery system charged by light with stable output and a series connected bendable battery pack with higher voltage is also demonstrated. It is anticipated that this bending-tolerant anode can be combined with further electrolytes and cathodes to develop new bendable energy systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Graphene composites as anode materials in lithium-ion batteries

Science.gov (United States)

Mazar Atabaki, M.; Kovacevic, R.

2013-03-01

Since the world of mobile phones and laptops has significantly altered by a big designer named Steve Jobs, the electronic industries have strived to prepare smaller, thinner and lower weight products. The giant electronic companies, therefore, compete in developing more efficient hardware such as batteries used inside the small metallic or polymeric frame. One of the most important materials in the production lines is the lithium-based batteries which is so famous for its ability in recharging as many times as a user needs. However, this is not an indication of being long lasted, as many of the electronic devices are frequently being used for a long time. The performance, chemistry, safety and above all cost of the lithium ion batteries should be considered when the design of the compounds are at the top concern of the engineers. To increase the efficiency of the batteries a combination of graphene and nanoparticles is recently introduced and it has shown to have enormous technological effect in enhancing the durability of the batteries. However, due to very high electronic conductivity, these materials can be thought of as preparing the anode electrode in the lithiumion battery. In this paper, the various approaches to characterize different types of graphene/nanoparticles and the process of preparing the anode for the lithium-ion batteries as well as their electrical properties are discussed.

Diagnostic Setup for Characterization of Near-Anode Processes in Hall Thrusters

International Nuclear Information System (INIS)

Dorf, L.; Raitses, Y.; Fisch, N.J.

2003-01-01

A diagnostic setup for characterization of near-anode processes in Hall-current plasma thrusters consisting of biased and emissive electrostatic probes, high-precision positioning system and low-noise electronic circuitry was developed and tested. Experimental results show that radial probe insertion does not cause perturbations to the discharge and therefore can be used for accurate near-anode measurements

High Performance Lithium-Ion Hybrid Capacitors Employing Fe3O4-Graphene Composite Anode and Activated Carbon Cathode.

Science.gov (United States)

Zhang, Shijia; Li, Chen; Zhang, Xiong; Sun, Xianzhong; Wang, Kai; Ma, Yanwei

2017-05-24

Lithium-ion capacitors (LICs) are considered as promising energy storage devices to realize excellent electrochemical performance, with high energy-power output. In this work, we employed a simple method to synthesize a composite electrode material consisting of Fe 3 O 4 nanocrystallites mechanically anchored among the layers of three-dimensional arrays of graphene (Fe 3 O 4 -G), which exhibits several advantages compared with other traditional electrode materials, such as high Li storage capacity (820 mAh g -1 at 0.1 A g -1 ), high electrical conductivity, and improved electrochemical stability. Furthermore, on the basis of the appropriated charge balance between cathode and anode, we successfully fabricated Fe 3 O 4 -G//activated carbon (AC) soft-packaging LICs with a high energy density of 120.0 Wh kg -1 , an outstanding power density of 45.4 kW kg -1 (achieved at 60.5 Wh kg -1 ), and an excellent capacity retention of up to 94.1% after 1000 cycles and 81.4% after 10 000 cycles. The energy density of the Fe 3 O 4 -G//AC hybrid device is comparable with Ni-metal hydride batteries, and its capacitive power capability and cycle life is on par with supercapacitors (SCs). Therefore, this lithium-ion hybrid capacitor is expected to bridge the gap between Li-ion battery and SCs and gain bright prospects in next-generation energy storage fields.

Reduced Graphene Oxide-Wrapped FeS2 Composite as Anode for High-Performance Sodium-Ion Batteries

Science.gov (United States)

Wang, Qinghong; Guo, Can; Zhu, Yuxuan; He, Jiapeng; Wang, Hongqiang

2018-06-01

Iron disulfide is considered to be a potential anode material for sodium-ion batteries due to its high theoretical capacity. However, its applications are seriously limited by the weak conductivity and large volume change, which results in low reversible capacity and poor cycling stability. Herein, reduced graphene oxide-wrapped FeS2 (FeS2/rGO) composite was fabricated to achieve excellent electrochemical performance via a facile two-step method. The introduction of rGO effectively improved the conductivity, BET surface area, and structural stability of the FeS2 active material, thus endowing it with high specific capacity, good rate capability, as well as excellent cycling stability. Electrochemical measurements show that the FeS2/rGO composite had a high initial discharge capacity of 1263.2 mAh g-1 at 100 mA g-1 and a high discharge capacity of 344 mAh g-1 at 10 A g-1, demonstrating superior rate performance. After 100 cycles at 100 mA g-1, the discharge capacity remained at 609.5 mAh g-1, indicating the excellent cycling stability of the FeS2/rGO electrode.

One-pot synthesis of NiO/C composite nanoparticles as anode materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lipeng, E-mail: lipeng.zhang@jcu.edu.au [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China); College of Science, Technology and Engineering, James Cook University, Douglas, Queensland 4811 (Australia); Mu, Jiechen; Wang, Zhao; Li, Guomin; Zhang, Yanling [School of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China); He, Yinghe, E-mail: yinghe.he@jcu.edu.au [College of Science, Technology and Engineering, James Cook University, Douglas, Queensland 4811 (Australia)

2016-06-25

Nanostructured NiO/C composite particles with controlled carbon content for lithium-ion battery anode were prepared via a one-pot hydrothermal approach and subsequent calcination in a high purity nitrogen atmosphere. The composites were composed of amorphous carbon and nanocrystalline NiO. The structure of the NiO crystals was determined with X-ray diffraction (XRD) analysis and the content of carbon was calculated from the energy dispersive spectroscopy (EDS) results. Scanning electron microscopy (SEM) images showed a relatively narrow distribution of particle size for both the neat NiO and NiO/C nanoparticles. Electrochemical performance measurements demonstrated that, after 50 cycles, NiO/C nanocomposites maintained a high reversible capacity of 585.9 mAh g{sup −1}, much higher than that of 356.1 mAh g{sup −1} of the neat NiO nanoparticles without carbon. The NiO/C nanoparticles also exhibited a remarkable discharge capacity, a high charge/discharge rate and an excellent cycle stability. The improvements can be attributed to the even carbon coating on the NiO particles, which significantly enhances the conductivity and improves the structural stability of the electrode. - Highlights: • NiO/C nanocomposite material is prepared via a one-pot hydrothermal approach. • Both NiO and NiO/C composite have a narrow particle size distribution. • Carbon in the NiO/C enhanced the conductivity and suppressed particle aggregation. • NiO/C composites maintained a reversible capacity of 585.9 mAh g{sup −1} after 50 cycles.

Lithium batteries, anodes, and methods of anode fabrication

KAUST Repository

Li, Lain-Jong; Wu, Feng-Yu; Kumar, Pushpendra; Ming, Jun

2016-01-01

Prelithiation of a battery anode carried out using controlled lithium metal vapor deposition. Lithium metal can be avoided in the final battery. This prelithiated electrode is used as potential anode for Li- ion or high energy Li-S battery

Structural comparison of anodic nanoporous-titania fabricated from single-step and three-step of anodization using two paralleled-electrodes anodizing cell

Directory of Open Access Journals (Sweden)

Mallika Thabuot

2016-02-01

Full Text Available Anodization of Ti sheet in the ethylene glycol electrolyte containing 0.38wt% NH4F with the addition of 1.79wt% H2O at room temperature was studied. Applied potential of 10-60 V and anodizing time of 1-3 h were conducted by single-step and three-step of anodization within the two paralleled-electrodes anodizing cell. Their structural and textural properties were investigated by X-ray diffraction (XRD and scanning electron microscopy (SEM. After annealing at 600°C in the air furnace for 3 h, TiO2-nanotubes was transformed to the higher proportion of anatase crystal phase. Also crystallization of anatase phase was enhanced as the duration of anodization as the final step increased. By using single-step of anodization, pore texture of oxide film was started to reveal at the applied potential of 30 V. Better orderly arrangement of the TiO2-nanotubes array with larger pore size was obtained with the increase of applied potential. The applied potential of 60 V was selected for the three-step of anodization with anodizing time of 1-3 h. Results showed that the well-smooth surface coverage with higher density of porous-TiO2 was achieved using prolonging time at the first and second step, however, discontinuity tube in length was produced instead of the long-vertical tube. Layer thickness of anodic oxide film depended on the anodizing time at the last step of anodization. More well arrangement of nanostructured-TiO2 was produced using three-step of anodization under 60 V with 3 h for each step.

Recovery Of Valuable Metals In Tin-Based Anodic Slimes By Carbothermic Reaction

OpenAIRE

Han Chulwoong; Kim Young-Min; Son Seong Ho; Choi Hanshin; Kim Tae Bum; Kim Yong Hwan

2015-01-01

This study investigated the recovery of anodic slimes by carbothermic reaction in the temperature range of 973~1,273K and amount of carbon as a function of time. Tin anodic slime samples were collected from the bottom of the electrolytic cells during the electro-refining of tin. The anodic slimes are consisted of high concentrated tin, silver, copper and lead oxides. The kinetics of reduction were determined by means of the weight-loss measurement technique. In order to understand in detail o...

Sandwiched Thin-Film Anode of Chemically Bonded Black Phosphorus/Graphene Hybrid for Lithium-Ion Battery.

Science.gov (United States)

Liu, Hanwen; Zou, Yuqin; Tao, Li; Ma, Zhaoling; Liu, Dongdong; Zhou, Peng; Liu, Hongbo; Wang, Shuangyin

2017-09-01

A facile vacuum filtration method is applied for the first time to construct sandwich-structure anode. Two layers of graphene stacks sandwich a composite of black phosphorus (BP), which not only protect BP from quickly degenerating but also serve as current collector instead of copper foil. The BP composite, reduced graphene oxide coated on BP via chemical bonding, is simply synthesized by solvothermal reaction at 140 °C. The sandwiched film anode used for lithium-ion battery exhibits reversible capacities of 1401 mAh g -1 during the 200th cycle at current density of 100 mA g -1 indicating superior cycle performance. Besides, this facile vacuum filtration method may also be available for other anode material with well dispersion in N-methyl pyrrolidone (NMP). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrothermal fabrication of Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube composite films on Ni anode and application in photoassisted water electrolysis

Energy Technology Data Exchange (ETDEWEB)

He, Hongbo; Chen, Aiping, E-mail: apchen@ecust.edu.cn; Lv, Hui; Dong, Haijun; Chang, Ming; Li, Chunzhong

2013-10-15

Highlights: •Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube photocatalysts were synthesized on Ni by hydrothermal method. •Structure of Ni{sub 3}S{sub 2} wrapped by TiO{sub 2} nanotubes improves remarkably stability of Ni{sub 3}S{sub 2}. •Ni{sub 3}S{sub 2}/TiO{sub 2} film on Ni has better H{sub 2} production performance than TiO{sub 2}-modified anode. -- Abstract: Nanostructured films of rhombohedral Ni{sub 3}S{sub 2} were hydrothermally synthesized on Ni and TiO{sub 2} nanotube layer, as substrates. A possible mechanism is proposed to explain the formation of rhombohedral Ni{sub 3}S{sub 2} nanostructures. The results of UV–vis spectrophotometric studies indicate that optical absorption spectrum of Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube composites could be extended to the visible region. As-synthesized Ni{sub 3}S{sub 2}/TiO{sub 2} nanotube composite films on Ni substrate had better (by about 40%) hydrogen production performance under the visible light irradiation, in comparison with the Ni anode modified by TiO{sub 2} nanotubes.

A Facile Electrophoretic Deposition Route to the Fe3O4/CNTs/rGO Composite Electrode as a Binder-Free Anode for Lithium Ion Battery.

Science.gov (United States)

Yang, Yang; Li, Jiaqi; Chen, Dingqiong; Zhao, Jinbao

2016-10-12

Fe 3 O 4 is regarded as an attractive anode material for lithium ion batteries (LIBs) due to its high theoretical capacity, natural abundance, and low cost. However, the poor cyclic performance resulting from the low conductivity and huge volume change during cycling impedes its application. Here we have developed a facile electrophoretic deposition route to fabricate the Fe 3 O 4 /CNTs (carbon nanotubes)/rGO (reduced graphene oxide) composite electrode, simultaneously achieving material synthesis and electrode assembling. Even without binders, the adhesion and mechanical firmness of the electrode are strong enough to be used for LIB anode. In this specific structure, Fe 3 O 4 nanoparticles (NPs) interconnected by CNTs are sandwiched by rGO layers to form a robust network with good conductivity. The resulting Fe 3 O 4 /CNTs/rGO composite electrode exhibits much improved electrochemical performance (high reversible capacity of 540 mAh g -1 at a very high current density of 10 A g -1 , and a remarkable capacity of 1080 mAh g -1 can be maintained after 450 cycles at 1 A g -1 ) compared with that of commercial Fe 3 O 4 NPs electrode.

Anodized aluminum on LDEF

Science.gov (United States)

Golden, Johnny L.

1993-01-01

A compilation of reported analyses and results obtained for anodized aluminum flown on the Long Duration Exposure Facility (LDEF) was prepared. Chromic acid, sulfuric acid, and dyed sulfuric acid anodized surfaces were exposed to the space environment. The vast majority of the anodized surface on LDEF was chromic acid anodize because of its selection as a thermal control coating for use on the spacecraft primary structure, trays, tray clamps, and space end thermal covers. Reports indicate that the chromic acid anodize was stable in solar absorptance and thermal emittance, but that contamination effects caused increases in absorptance on surfaces exposed to low atomic oxygen fluences. There were some discrepancies, however, in that some chromic acid anodized specimens exhibited significant increases in absorptance. Sulfuric acid anodized surfaces also appeared stable, although very little surface area was available for evaluation. One type of dyed sulfuric acid anodize was assessed as an optical baffle coating and was observed to have improved infrared absorptance characteristics with exposure on LDEF.

Improving pitting corrosion resistance of aluminum by anodizing process

International Nuclear Information System (INIS)

John, P.; Khan, I.U.

2013-01-01

Summary: Anodizing of aluminum was studied in sulphuric/citric/boric acid electrolyte system to improve pitting corrosion resistance. Maximum oxide film thickness was obtained using 5% sulphuric acid, 3% citric acid and 0.5% boric acid electrolyte composition. The corrosion resistance of aluminum sample was determined to find the effectiveness of oxide coating by potentiodynamic polarization test. The surface morphology of aluminum samples was investigated using scanning electron microscope (SEM) before and after corrosion test. It was found that the coated aluminum sample obtained by anodizing in sulphuric/citric/boric acid electrolyte system exhibited better pitting corrosion resistance with no significant difference in surface morphology. (author)

An in situ carbonization-replication method to synthesize mesostructured WO3/C composite as nonprecious-metal anode catalyst in PEMFC.

Science.gov (United States)

Cui, Xiangzhi; Hua, Zile; Wei, Chenyang; Shu, Zhu; Zhang, Liangxia; Chen, Hangrong; Shi, Jianlin

2013-02-01

A meostructured WO(3)/C composite with crystalline framework and high electric conductivity has been synthesized by a new in situ carbonization-replication route using the block copolymer (poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)) present in situ in the pore channels of mesoporous silica template as carbon source. X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, thermogravimetry differential thermal analysis, and N(2) adsorption techniques were adopted for the structural characterization. Cyclic voltammetry, chronoamperometry, and single-cell test for hydrogen electrochemical oxidation were adopted to characterize the electrochemical activities of the mesoporous WO(3)/C composite. The carbon content and consequent electric conductivity of these high-surface-area (108-130 m(2) g(-1)) mesostructured WO(3)/C composite materials can be tuned by variation of the duration of heat treatment, and the composites exhibited high and stable electrochemical catalytic activity. The single-cell test results indicated that the mesostructured WO(3)/C composites showed clear electrochemical catalytic activity toward hydrogen oxidation at 25 °C, which makes them potential non-precious-metal anode catalysts in proton exchange membrane fuel cell. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anode plasma dynamics in an extraction applied-B ion diode: effects on divergence, ion species and parasitic load

International Nuclear Information System (INIS)

Greenly, J.B.; Appartaim, R.K.; Olson, J.C.

1996-01-01

Analysis of data from the LION (1.2 MV, 300 kA, 40 ns) extraction applied-B diode allows a number of inferences regarding the effect of anode plasma dynamics on ion beam divergence, ion species composition, and diode impedance and power coupling. The two dominant features of anode plasma dynamics observed on LION are (1) plasma expansion away from the solid anode surface and into the accelerating gap during the beam pulse, and (2) evolution of the composition of the plasma during the pulse. The data presented in this paper characterize the plasma expansion, and suggest a possible picture of the mechanism of the plasma dynamics that could produce these basic features. (J.U.). 2 figs., 5 refs

Anode plasma dynamics in an extraction applied-B ion diode: effects on divergence, ion species and parasitic load

Energy Technology Data Exchange (ETDEWEB)

Greenly, J B; Appartaim, R K; Olson, J C [Cornell Univ., Ithaca, NY (United States). Lab. of Plasma Studies

1997-12-31

Analysis of data from the LION (1.2 MV, 300 kA, 40 ns) extraction applied-B diode allows a number of inferences regarding the effect of anode plasma dynamics on ion beam divergence, ion species composition, and diode impedance and power coupling. The two dominant features of anode plasma dynamics observed on LION are (1) plasma expansion away from the solid anode surface and into the accelerating gap during the beam pulse, and (2) evolution of the composition of the plasma during the pulse. The data presented in this paper characterize the plasma expansion, and suggest a possible picture of the mechanism of the plasma dynamics that could produce these basic features. (J.U.). 2 figs., 5 refs.

MnO{sub 2} nanorods/3D-rGO composite as high performance anode materials for Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongdong; Hu, Zhongli; Su, Yongyao; Ruan, Haibo; Hu, Rong [Research Institute for New Materials Technology, Chongqing University of Arts and Sciences, Chongqing 402160 (China); Zhang, Lei, E-mail: leizhang0215@126.com [College of Life Science, Chongqing Normal University, Chongqing 401331 (China)

2017-01-15

Highlights: • MnO{sub 2} nanorods/3D-rGO composite has been synthesized by a simple in situ hydrothermal methord. • MnO{sub 2} nanorods/3D-rGO composite exhibits high reversible capacity, outstanding rate capacity and excellent cyclic stability. • Building metal oxides/3D-rGO composite is an effective way for improving the electrochemical performance of Li-ion batteries. - Abstract: MnO{sub 2} nanorods/three-dimensional reduced graphene oxide (3D-rGO) composite has been synthesized by a simple in situ hydrothermal methord. The X-ray diffraction (XRD) pattern of the as-prepared composite reveals tetragonal structure of α-MnO{sub 2.} Raman spectroscopic and X-ray photoelectron spectroscopy (XPS) of the samples confirm the coexistence of MnO{sub 2} and graphene. The Brunauer-Emmett-Teller (BET) analysis shows the large surface area of the composite. The electron microscopy images of the as-synthesized products reveals the MnO{sub 2} nanorods are homogeneously grown on 3D-rGO matrix. Electrochemical characterization exhibits the MnO{sub 2} nanorods/3D-rGO composite with large reversible capacity (595 mA h g{sup −1} over 60 cycles at 100 mA g{sup −1}), high coulombic efficiency (above 99%), excellent rate capability and good cyclic stability. The superior electrochemical performance can be attributed to the turf-like nanostructure of composite, high capacity of MnO{sub 2} and superior electrical conductivity of 3D-rGO. It suggests that MnO{sub 2} nanorods/3D-rGO composite will be a promising anode material for Li-ion batteries.

Anodic oxidation

CERN Document Server

Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

2013-01-01

Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

The Optimized Tin Dioxide-Carbon Nanocomposites as High-performance Anode for Lithium ion Battery with a long cycle life

International Nuclear Information System (INIS)

Wan, Yuanxin; Sha, Ye; Deng, Weijia; Zhu, Qing; Chen, Zhen; Wang, Xiaoliang; Chen, Wei; Xue, Gi; Zhou, Dongshan

2015-01-01

Tin dioxide (SnO 2 ) is one of the most promising anode materials for the next generation Li-ion batteries due to its high capacity. To solve the problems caused by the large volume change (over 300%) and the aggregation of the tin particles formed during cycling, nano SnO 2 /C composites are proved to be ideal anode materials for high performance Li-ion batteries. However, it is still a challenge to disperse ultrasmall (<6 nm) SnO 2 nanoparticles with uniform size in carbon matrix. Here, we report a facile hydrothermal way to get such optimized nano SnO 2 /C composite, in which well dispersed ultrasmall SnO 2 nanocrystals (3∼5 nm) are embedded in a conductive carbon matrix. With this anode, we demonstrate a high stable capacity of 928 mAh g −1 based on the total mass of the composite at a current density of 500 mA g −1 . At high current density of 2 A g −1 , this composite anode shows a capacity of 853 mAh g −1 in the first charge, in such high current density, we can even get a capacity retention of more than 91% (779 mAh g −1 ) after 1000 cycles

Hybrid lithium-ion capacitor with LiFePO4/AC composite cathode - Long term cycle life study, rate effect and charge sharing analysis

Science.gov (United States)

Shellikeri, A.; Yturriaga, S.; Zheng, J. S.; Cao, W.; Hagen, M.; Read, J. A.; Jow, T. R.; Zheng, J. P.

2018-07-01

Energy storage devices, which can combine the advantages of lithium-ion battery with that of electric double layer capacitor, are of prime interest. Recently, composite cathodes, which combine a battery material with capacitor material, have shown promise in enhancing life cycle and energy/power performances. Lithium-ion capacitor (LIC), with unique charge storage mechanism of combining a pre-lithiated battery anode with a capacitor cathode, is one such device which has the potential to synergistically incorporate the composite cathode to enhance capacity and cycle life. We report here a hybrid LIC consisting of a lithium iron phosphate (LiFePO4-LFP)/Activated Carbon composite cathode in combination with a hard carbon anode, by integrating the cycle life and capacity enhancing strategies of a dry method of electrode fabrication, anode pre-lithiation and a 3:1 anode to cathode capacity ratio, demonstrating a long cycle life, while elaborating on the charge sharing between the faradaic and non-faradaic mechanism in the battery and capacitor materials, respectively in the composite cathode. An excellent cell capacity retention of 94% (1000 cycles at 1C) and 92% (100,000 cycles at 60C) were demonstrated, while retaining 78% (over 6000 cycles at 2.7C) and 67% (over 70,000 cycles at 43C) of the LFP capacity in the composite cathode.

The iron and cerium oxide influence on the electric conductivity and the corrosion resistance of anodized aluminium

International Nuclear Information System (INIS)

Souza, Kellie Provazi de

2006-01-01

The influence of different treatments on the aluminum system covered with aluminum oxide is investigated. The aluminum anodization in sulphuric media and in mixed sulphuric and phosphoric media was used to alter the corrosion resistance, thickness, coverage degree and microhardness of the anodic oxide. Iron electrodeposition inside the anodic oxide was used to change its electric conductivity and corrosion resistance. Direct and pulsed current were used for iron electrodeposition and the Fe(SO 4 ) 2 (NH 4 ) 2 .6H 2 O electrolyte composition was changed with the addition of boric and ascorbic acids. To the sealing treatment the CeCl 3 composition was varied. The energy dispersive x-ray (EDS), the x-ray fluorescence spectroscopy (FRX) and the morphologic analysis by scanning electronic microscopy (SEM) allowed to verify that, the pulsed current increase the iron content inside the anodic layer and that the use of the additives inhibits the iron oxidation. The chronopotentiometric curves obtained during iron electrodeposition indicated that the boric and ascorbic acids mixture increased the electrodeposition process efficiency. The electrochemical impedance spectroscopy (EIE), the Vickers (Hv) microhardness measurements and morphologic analysis evidenced that the sealing treatment improves the corrosion resistance of the anodic film modified with iron. The electrical impedance (EI) technique allowed to prove the electric conductivity increase of the anodized aluminum with iron electrodeposited even after the cerium low concentration treatment. Iron nanowires were prepared by using the anodic oxide pores as template. (author)

Comparison of microbial electrolysis cells operated with added voltage or by setting the anode potential

KAUST Repository

Nam, Joo-Youn

2011-08-01

Hydrogen production in a microbial electrolysis cell (MEC) can be achieved by either setting the anode potential with a potentiostat, or by adding voltage to the circuit with a power source. In batch tests the largest total gas production (46 ± 3 mL), lowest energy input (2.3 ± 0.3 kWh/m 3 of H2 generated), and best overall energy recovery (E+S = 58 ± 6%) was achieved at a set anode potential of EAn = -0.2 V (vs Ag/AgCl), compared to set potentials of -0.4 V, 0 V and 0.2 V, or an added voltage of Eap = 0.6 V. Gas production was 1.4 times higher with EAn = -0.2 V than with Eap = 0.6 V. Methane production was also reduced at set anode potentials of -0.2 V and higher than the other operating conditions. Continuous flow operation of the MECs at the optimum condition of EAn = -0.2 V initially maintained stable hydrogen gas production, with 68% H2 and 21% CH4, but after 39 days the gas composition shifted to 55% H2 and 34% CH 4. Methane production was not primarily anode-associated, as methane was reduced to low levels by placing the anode into a new MEC housing. These results suggest that MEC performance can be optimized in terms of hydrogen production rates and gas composition by setting an anode potential of -0.2 V, but that methanogen proliferation must be better controlled on non-anodic surfaces. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Modelling the growth process of porous aluminum oxide film during anodization

International Nuclear Information System (INIS)

Aryslanova, E M; Alfimov, A V; Chivilikhin, S A

2015-01-01

Currently it has become important for the development of metamaterials and nanotechnology to obtain regular self-assembled structures. One such structure is porous anodic alumina film that consists of hexagonally packed cylindrical pores. In this work we consider the anodization process, our model takes into account the influence of layers of aluminum and electrolyte on the rate of growth of aluminum oxide, as well as the effect of surface diffusion. In present work we consider those effects. And as a result of our model we obtain the minimum distance between centers of alumina pores in the beginning of anodizing process. (paper)

Modelling the growth process of porous aluminum oxide film during anodization

Science.gov (United States)

Aryslanova, E. M.; Alfimov, A. V.; Chivilikhin, S. A.

2015-11-01

Currently it has become important for the development of metamaterials and nanotechnology to obtain regular self-assembled structures. One such structure is porous anodic alumina film that consists of hexagonally packed cylindrical pores. In this work we consider the anodization process, our model takes into account the influence of layers of aluminum and electrolyte on the rate of growth of aluminum oxide, as well as the effect of surface diffusion. In present work we consider those effects. And as a result of our model we obtain the minimum distance between centers of alumina pores in the beginning of anodizing process.

Carbon nanotube-wrapped Fe2O3 anode with improved performance for lithium-ion batteries

Directory of Open Access Journals (Sweden)

Guoliang Gao

2017-03-01

Full Text Available Metall oxides have been proven to be potential candidates for the anode material of lithium-ion batteries (LIBs because they offer high theoretical capacities, and are environmentally friendly and widely available. However, the low electronic conductivity and severe irreversible lithium storage have hindered a practical application. Herein, we employed ethanolamine as precursor to prepare Fe2O3/COOH-MWCNT composites through a simple hydrothermal synthesis. When these composites were used as electrode material in lithium-ion batteries, a reversible capacity of 711.2 mAh·g−1 at a current density of 500 mA·g−1 after 400 cycles was obtained. The result indicated that Fe2O3/COOH-MWCNT composite is a potential anode material for lithium-ion batteries.

Elaboration, physical and electrochemical characterizations of CO tolerant PEMFC anode materials. Study of platinum-molybdenum and platinum-tungsten alloys and composites; Elaborations et caracterisations electrochimiques et physiques de materiaux d'anode de PEMFC peu sensibles a l'empoisonnement par CO: etude d'alliages et de composites a base de platine-molybdene et de platine-tungstene

Energy Technology Data Exchange (ETDEWEB)

Peyrelade, E.

2005-06-15

PEMFC development is hindered by the CO poisoning ability of the anode platinum catalyst. It has been previously shown that the oxidation potential of carbon monoxide adsorbed on the platinum atoms can be lowered using specific Pt based catalysts, either metallic alloys or composites. The objective is then to realize a catalyst for which the CO oxidation is compatible with the working potential of a PEMFC anode. In our approach, to enhance the CO tolerance of platinum based catalyst supported on carbon, we studied platinum-tungsten and platinum-molybdenum alloys and platinum-metal oxide materials (Pt-WO{sub x} and Pt-MoO{sub x}). The platinum based alloys demonstrate a small effect of the second metal towards the oxidation of carbon monoxide. The platinum composites show a better tolerance to carbon monoxide. Electrochemical studies on both Pt-MoO{sub x} and Pt-WO{sub x} demonstrate the ability of the metal-oxides to promote the ability of Pt to oxidize CO at low potentials. However, chrono-amperometric tests reveal a bigger influence of the tungsten oxide. Complex chemistry reactions on the molybdenum oxide surface make it more difficult to observe. (author)

Cracking in Si-based anodes for Li-ion batteries

NARCIS (Netherlands)

Aifantis, KE; Dempsey, JP; Hackney, SA

2005-01-01

In attempts to increase the anode capacity of rechargeable Li-ion batteries, composite materials with micro- and nano-scale domains of Li active material surrounded by Li inactive material are being investigated. Materials such as Si, Al and Sn that provide capacities between 900 and 4000 mAh g(-1)

Effect of anodization on the surface characteristics and electrochemical behaviour of zirconium in artificial saliva.

Science.gov (United States)

Romonti, Daniela E; Gomez Sanchez, Andrea V; Milošev, Ingrid; Demetrescu, Ioana; Ceré, Silvia

2016-05-01

The paper is focused on elaboration of ZrO2 films on pure zirconium via anodizing in phosphoric acid with and without fluoride at constant potentials of 30 V and 60 V. The structure and composition of the films were investigated using scanning electronic microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The composition of the oxides formed at both potentials can be identified as monoclinic ZrO2. In addition to Zr and O, the layers formed in phosphoric acid contain phosphorus originating from the phosphoric acid. When the phosphoric acid solution contains NaF, fluorine is also incorporated into the oxide layer. The oxides formed at a higher voltage have greater roughness than those formed at 30 V. Anodized samples exhibit smaller current densities during anodic polarization compared to the as-received zirconium covered with native oxide. Copyright © 2016 Elsevier B.V. All rights reserved.

Construction of SnO2-Graphene Composite with Half-Supported Cluster Structure as Anode toward Superior Lithium Storage Properties.

Science.gov (United States)

Zhu, Chengling; Chen, Zhixin; Zhu, Shenmin; Li, Yao; Pan, Hui; Meng, Xin; Imtiaz, Muhammad; Zhang, Di

2017-06-12

Inspired by nature, herein we designed a novel construction of SnO 2 anodes with an extremely high lithium storage performance. By utilizing small sheets of graphene oxide, the partitioned-pomegranate-like structure was constructed (SnO 2 @C@half-rGO), in which the porous clusters of SnO 2 nanoparticles are partially supported by reduced graphene oxide sheets while the rest part is exposed (half-supported), like partitioned pomegranates. When served as anode for lithium-ion batteries, SnO 2 @C@half-rGO exhibited considerably high specific capacity (1034.5 mAh g -1 after 200 cycles at 100 mA g -1 ), superior rate performance and remarkable durability (370.3 mAh g -1 after 10000 cycles at 5 A g -1 ). When coupled with graphitized porous carbon cathode for lithium-ion hybrid capacitors, the fabricated devices delivered a high energy density of 257 Wh kg -1 at ∼200 W kg -1 and maintained 79 Wh kg -1 at a super-high power density of ∼20 kW kg -1 within a wide voltage window up to 4 V. This facile and scalable approach demonstrates a new architecture for graphene-based composite for practical use in energy storage with high performance.

Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium

Energy Technology Data Exchange (ETDEWEB)

Sowa, Maciej; Greń, Katarzyna [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Kukharenko, Andrey I. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Ural Federal University, Mira Street 19, 620002 Yekaterinburg, Mira str. 19 (Russian Federation); Korotin, Danila M. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Michalska, Joanna [Faculty of Materials Engineering and Metallurgy, Silesian University of Technology, Krasińskiego Street 8, 40-019 Katowice (Poland); Szyk-Warszyńska, Lilianna; Mosiałek, Michał [Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek Street 8, 30-239 Kraków (Poland); Żak, Jerzy [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Pamuła, Elżbieta [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza Avenue 30, 30-059 Kraków (Poland); Kurmaev, Ernst Z. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Cholakh, Seif O. [Ural Federal University, Mira Street 19, 620002 Yekaterinburg, Mira str. 19 (Russian Federation); Simka, Wojciech, E-mail: wojciech.simka@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland)

2014-09-01

The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1 mol dm{sup −3} phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species. - Highlights: • Pure niobium was electropolished and subsequently anodised in a H{sub 3}PO{sub 4} solution. • Phosphorus was successfully introduced into the oxide layers after the treatment. • Corrosion resistance of niobium in Ringer's solution was improved after anodising.

Effect of Silica Sol on Boric-sulfuric Acid Anodic Oxidation of LY12CZ Aluminum Alloy

Directory of Open Access Journals (Sweden)

LIU Hui-cong

2016-07-01

Full Text Available Aluminum alloy anodizing coatings were prepared for LY12CZ in the boric-sulfuric acid solution (45g/L sulfuric acid,8g/L boric acid with the addition of 10%,20%,30% (volume fractionsilica sol,with the gradient voltage of 15V. The current and voltage transients of the anodizing process were collected by data collection instrument. The surface morphologies,microstructure and chemical composition of the anodic coatings were characterized by scanning electron microscopy (SEM. The corrosion resistance was examined by neutral salt spray,electrochemical impedance spectroscopy (EIS test and titrating test. The results show that the different concentration of silica sol addition can influence the forming and dissolution of anodizing coatings,improve the compactness smoothness and corrosion resistance during the anodizing process in the boric-sulfuric acid solution.

Structural Engineering of Nanoporous Anodic Alumina Photonic Crystals by Sawtooth-like Pulse Anodization.

Science.gov (United States)

Law, Cheryl Suwen; Santos, Abel; Nemati, Mahdieh; Losic, Dusan

2016-06-01

This study presents a sawtooth-like pulse anodization approach aiming to create a new type of photonic crystal structure based on nanoporous anodic alumina. This nanofabrication approach enables the engineering of the effective medium of nanoporous anodic alumina in a sawtooth-like manner with precision. The manipulation of various anodization parameters such as anodization period, anodization amplitude, number of anodization pulses, ramp ratio and pore widening time allows a precise control and fine-tuning of the optical properties (i.e., characteristic transmission peaks and interferometric colors) exhibited by nanoporous anodic alumina photonic crystals (NAA-PCs). The effect of these anodization parameters on the photonic properties of NAA-PCs is systematically evaluated for the establishment of a fabrication methodology toward NAA-PCs with tunable optical properties. The effective medium of the resulting NAA-PCs is demonstrated to be optimal for the development of optical sensing platforms in combination with reflectometric interference spectroscopy (RIfS). This application is demonstrated by monitoring in real-time the formation of monolayers of thiol molecules (11-mercaptoundecanoic acid) on the surface of gold-coated NAA-PCs. The obtained results reveal that the adsorption mechanism between thiol molecules and gold-coated NAA-PCs follows a Langmuir isotherm model, indicating a monolayer sorption mechanism.

Post-mortem analysis on LiFePO4|Graphite cells describing the evolution & composition of covering layer on anode and their impact on cell performance

Science.gov (United States)

Lewerenz, Meinert; Warnecke, Alexander; Sauer, Dirk Uwe

2017-11-01

During cyclic aging of lithium-ion batteries the formation of a μm-thick covering layer on top of the anode facing the separator is found on top of the anode. In this work several post-mortem analyses of cyclic aged cylindrical LFP|Graphite cells are evaluated to give a detailed characterization of the covering layer and to find possible causes for the evolution of such a layer. The analyses of the layer with different methods return that it consists to high percentage of plated active lithium, deposited Fe and products of a solid electrolyte interphase (SEI). The deposition is located mainly in the center of the cell symmetrical to the coating direction. The origin of these depositions is assumed in locally overcharged particles, Fe deposition or inhomogeneous distribution of capacity density. As a secondary effect the deposition on one side increases the thickness locally; thereafter a pressure-induced overcharging due to charge agglomeration of the back side of the anode occurs. Finally a compact and dense covering layer in a late state of aging leads to deactivation of the covered parts of the anode and cathode due to suppressed lithium-ion conductivity. This leads to increasing slope of capacity fade and increase of internal resistance.

In situ characterization of nanoscale catalysts during anodic redox processes

Energy Technology Data Exchange (ETDEWEB)

Sharma, Renu [National Institute of Standards and Technology; Crozier, Peter [Arizona State University; Adams, James [Arizona State University

2013-09-19

Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

Electrochemical properties of SnO{sub 2}/carbon composite materials as anode material for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Wang Jie [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhao Hailei, E-mail: hlzhao@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Lab of New Energy Materials and Technologies, Beijing 100083 (China); Liu Xiaotong; Wang Jing; Wang Chunmei [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

2011-07-15

Highlights: > SnO{sub 2}/carbon powders with a cauliflower-like particle structure were synthesized. > Post-annealing can improve the electrochemical properties of SnO{sub 2}/C composite. > The 500 deg. C-annealed SnO{sub 2}/C shows the best electrochemical performance. > The lithium ion diffusion coefficients of the SnO{sub 2}/C electrodes were calculated. - Abstract: SnO{sub 2}/carbon composite anode materials were synthesized from SnCl{sub 4}.5H{sub 2}O and sucrose via a hydrothermal route and a post heat-treatment. The synthesized spherical SnO{sub 2}/carbon powders show a cauliflower-like micro-sized structure. High annealing temperature results in partial reduction of SnO{sub 2}. Metallic Sn starts to emerge at 500 deg. C. High Sn content in SnO{sub 2}/carbon composite is favorable for the increase of initial coulombic efficiency but not for the cycling stability. The SnO{sub 2}/carbon annealed at 500 deg. C exhibits high specific capacity ({approx}400 mAh g{sup -1}), stable cycling performance and good rate capability. The generation of Li{sub 2}O in the first lithiation process can prevent the aggregation of active Sn, while the carbon component can buffer the big volume change caused by lithiation/delithiation of active Sn. Both of them make contribution to the better cycle stability.

Effectiveness of anode in a solid oxide fuel cell with hydrogen/oxygen mixed gases

Energy Technology Data Exchange (ETDEWEB)

Kellogg, Isaiah D. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO (United States); Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO (United States); Koylu, Umit O. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO (United States); Petrovsky, Vladimir; Dogan, Fatih [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO (United States)

2009-06-15

A porous Ni/YSZ cermet in mixed hydrogen and oxygen was investigated for its ability to decrease oxygen activity as the anode of a single chamber SOFC. A cell with a dense 300 {mu}m YSZ electrolyte was operated in a double chamber configuration. The Ni-YSZ anode was exposed to a mixture of hydrogen and oxygen of varying compositions while the cathode was exposed to oxygen. Double chamber tests with mixed gas on the anode revealed voltage oscillations linked to lowered power generation and increased resistance. Resistance measurements of the anode during operation revealed a Ni/NiO redox cycle causing the voltage oscillations. The results of these tests, and future tests of similar format, could be useful in the development of single chamber SOFC using hydrogen as fuel. (author)

Modelling of structure and properties of soft carbons with application to carbon anode baking

Energy Technology Data Exchange (ETDEWEB)

Gundersen, Oeyvind

1998-11-01

This work deals with topics related to modelling and control of ring furnaces for the baking of carbon anodes used in aluminium electrolysis. Anodes made of a granular coke and coal tar pitch are used in aluminium electrolysis. The anode properties are imperative for successful operation of the aluminium smelters. After mixing and forming the anode paste, heat treatment of the carbon blocks takes place in so-called ring furnaces. A ring furnace consists of a series of heat treatment sections where each section is loaded with a batch of anodes. The heat treatment of the anodes in a section consumes a lot of energy, and the anode properties partly depend on the heat treatment program. Previous work in the field of ring furnace modelling, operation and control is shortly reviewed. Both petroleum coke and coal tar pitch belong to the group of soft carbons. Models for structural parameters and porosity of soft carbons are developed. Furthermore, a new model for pyrolysis of coal tar pitch is proposed. Based on the models for pyrolysis, structure and porosity, new models for properties of single phase carbons and composite anodes are developed. These models are suitable for use in optimization of the baking process. A detailed mathematical model of a part of the heat treatment process is formulated in three spatial dimensions. The model is based on first principle descriptions of fundamental physical and chemical phenomena and the resulting model appears as a set of partial differential equations. The spatial differential operators are discretized by using the finite volume approach. In this way, a high dimensional nonlinear state space model is obtained. The model has been simulated using the method of lines. A vector of quantities which describes the anode properties is defined. This property vector constitutes a systematic definition of anode quality where the quality parameters are calculated as nonlinear transformations of the state space vector. Models are derived

Modelling of structure and properties of soft carbons with application to carbon anode baking

Energy Technology Data Exchange (ETDEWEB)

Gundersen, Oeyvind

1998-11-01

This work deals with topics related to modelling and control of ring furnaces for the baking of carbon anodes used in aluminium electrolysis. Anodes made of a granular coke and coal tar pitch are used in aluminium electrolysis. The anode properties are imperative for successful operation of the aluminium smelters. After mixing and forming the anode paste, heat treatment of the carbon blocks takes place in so-called ring furnaces. A ring furnace consists of a series of heat treatment sections where each section is loaded with a batch of anodes. The heat treatment of the anodes in a section consumes a lot of energy, and the anode properties partly depend on the heat treatment program. Previous work in the field of ring furnace modelling, operation and control is shortly reviewed. Both petroleum coke and coal tar pitch belong to the group of soft carbons. Models for structural parameters and porosity of soft carbons are developed. Furthermore, a new model for pyrolysis of coal tar pitch is proposed. Based on the models for pyrolysis, structure and porosity, new models for properties of single phase carbons and composite anodes are developed. These models are suitable for use in optimization of the baking process. A detailed mathematical model of a part of the heat treatment process is formulated in three spatial dimensions. The model is based on first principle descriptions of fundamental physical and chemical phenomena and the resulting model appears as a set of partial differential equations. The spatial differential operators are discretized by using the finite volume approach. In this way, a high dimensional nonlinear state space model is obtained. The model has been simulated using the method of lines. A vector of quantities which describes the anode properties is defined. This property vector constitutes a systematic definition of anode quality where the quality parameters are calculated as nonlinear transformations of the state space vector. Models are derived

The spectral emissivity of the anode of a carbon arc.

Science.gov (United States)

Schurer, K

1968-03-01

Data in the literature on the spectral emissivity of carbon and graphite show a great divergence, ranging from 0.75 to 0.99 in the visible region. A new determination has been undertaken at a number of wavelengths using an integrating sphere and modulated light. Emissivities ranging from 0.99 in the visible to 0.96 at 0.28 micro and 1.7 micro have been found for several different graphite anodes; the values for lampblack anodes are about 0.005 lower. There is a good agreement with the highest values thus far published. Most of the literature data on the spectral radiance of the anode are consistent with the emissivities found by the present author.

Lifetime of anode polymer in magnetically insulated ion diodes for high-intensity pulsed ion beam generation

International Nuclear Information System (INIS)

Zhu, X. P.; Dong, Z. H.; Han, X. G.; Xin, J. P.; Lei, M. K.

2007-01-01

Generation of high-intensity pulsed ion beam (HIPIB) has been studied experimentally using polyethylene as the anode polymer in magnetically insulated ion diodes (MIDs) with an external magnetic field. The HIPIB is extracted from the anode plasma produced during the surface discharging process on polyethylene under the electrical and magnetic fields in MIDs, i.e., high-voltage surface breakdown (flashover) with bombardments by electrons. The surface morphology and the microstructure of the anode polymer are characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The surface roughening of the anode polymer results from the explosive release of trapped gases or newly formed gases under the high-voltage discharging, leaving fractured surfaces with bubble formation. The polyethylene in the surface layer degrades into low-molecular-weight polymers such as polyethylene wax and paraffin under the discharging process. Both the surface roughness and the fraction of low molecular polymers apparently increase as the discharging times are prolonged for multipulse HIPIB generation. The changes in the surface morphology and the composition of anode polymer lead to a noticeable decrease in the output of ion beam intensity, i.e., ion current density and diode voltage, accompanied with an increase in instability of the parameters with the prolonged discharge times. The diode voltage (or surface breakdown voltage of polymer) mainly depends on the surface morphology (or roughness) of anode polymers, and the ion current density on the composition of anode polymers, which account for the two stages of anode polymer degradation observed experimentally, i.e., stage I which has a steady decrease of the two parameters and stage II which shows a slow decrease, but with an enhanced fluctuation of the two parameters with increasing pulses of HIPIB generation

Silicon-Encapsulated Hollow Carbon Nanofiber Networks as Binder-Free Anodes for Lithium Ion Battery

Directory of Open Access Journals (Sweden)

Ding Nan

2014-01-01

Full Text Available Silicon-encapsulated hollow carbon nanofiber networks with ample space around the Si nanoparticles (hollow Si/C composites were successfully synthesized by dip-coating phenolic resin onto the surface of electrospun Si/PVA nanofibers along with the subsequent solidification and carbonization. More importantly, the structure and Si content of hollow Si/C composite nanofibers can be effectively tuned by merely varying the concentration of dip solution. As-synthesized hollow Si/C composites show excellent electrochemical performance when they are used as binder-free anodes for Li-ion batteries (LIBs. In particular, when the concentration of resol/ethanol solution is 3.0%, the product exhibits a large capacity of 841 mAh g−1 in the first cycle, prominent cycling stability, and good rate capability. The discharge capacity retention of it was ~90%, with 745 mAh g−1 after 50 cycles. The results demonstrate that the hollow Si/C composites are very promising as alternative anode candidates for high-performance LIBs.

Anodic composite deposition of RuO2/reduced graphene oxide/carbon nanotube for advanced supercapacitors

Science.gov (United States)

Hu, Chi-Chang; Wang, Chia-Wei; Chang, Kuo-Hsin; Chen, Ming-Guan

2015-07-01

Anodic composite deposition is demonstrated to be a unique method for fabricating a ternary ruthenium dioxide/reduced graphene oxide/carbon nanotube (RuO2 · xH2O/rGO/CNT, denoted as RGC) nanocomposite onto Ti as an advanced electrode material for supercapacitors. The rGO/CNT composite in RGCs acts as a conductive backbone to facilitate the electron transport between current collector and RuO2 · xH2O nanoparticles (NPs), revealed by the high total specific capacitance (CS,T = 808 F g-1) of RGC without annealing. The contact resistance among RuO2 · xH2O NPs is improved by low-temperature annealing at 150 °C (RGC-150), which renders slight sintering and enhances the specific capacitance of RuO2 · xH2O to achieve 1200 F g-1. The desirable nanocomposite microstructure of RGC-150 builds up the smooth pathways of both protons and electrons to access the active oxy-ruthenium species. This nanocomposite exhibits an extremely high CS,T of 973 F g-1 at 25 mV s-1 (much higher than 435 F g-1 of an annealed RuO2 · xH2O deposit) and good capacitance retention (60.5% with scan rate varying from 5 to 500 mV s-1), revealing an advanced electrode material for high-performance supercapacitors.

Hierarchical structured graphene/metal oxide/porous carbon composites as anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Guo, Rong; Yue, Wenbo; Ren, Yu; Zhou, Wuzong

2016-01-01

Highlights: • CeO 2 and Co 3 O 4 nanoparticles display different behavior within CMK-3. • CMK-3-CeO 2 and Co 3 O 4 show various electrochemical properties • CMK-3-CeO 2 and Co 3 O 4 are further wrapped by graphene nanosheets. • Graphene-encapsulated composites show better electrochemical performances. - Abstract: As a novel anode material for lithium-ion batteries, CeO 2 displays imperceptible volumetric and morphological changes during the lithium insertion and extraction processes, and thereby exhibits good cycling stability. However, the low theoretical capacity and poor electronic conductivity of CeO 2 hinder its practical application. In contrast, Co 3 O 4 possesses high theoretical capacity, but undergoes huge volume change during cycling. To overcome these issues, CeO 2 and Co 3 O 4 nanoparticles are formed inside the pores of CMK-3 and display various electrochemical behaviors due to the different morphological structures of CeO 2 and Co 3 O 4 within CMK-3. Moreover, the graphene/metal oxide/CMK-3 composites with a hierarchical structure are then prepared and exhibit better electrochemical performances than metal oxides with or without CMK-3. This novel synthesis strategy is hopefully employed in the electrode materials design for Li-ion batteries or other energy conversion and storage devices.

Growth behavior of anodic oxide formed by aluminum anodizing in glutaric and its derivative acid electrolytes

Science.gov (United States)

Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2014-12-01

The growth behavior of anodic oxide films formed via anodizing in glutaric and its derivative acid solutions was investigated based on the acid dissociation constants of electrolytes. High-purity aluminum foils were anodized in glutaric, ketoglutaric, and acetonedicarboxylic acid solutions under various electrochemical conditions. A thin barrier anodic oxide film grew uniformly on the aluminum substrate by glutaric acid anodizing, and further anodizing caused the film to breakdown due to a high electric field. In contrast, an anodic porous alumina film with a submicrometer-scale cell diameter was successfully formed by ketoglutaric acid anodizing at 293 K. However, the increase and decrease in the temperature of the ketoglutaric acid resulted in non-uniform oxide growth and localized pitting corrosion of the aluminum substrate. An anodic porous alumina film could also be fabricated by acetonedicarboxylic acid anodizing due to the relatively low dissociation constants associated with the acid. Acid dissociation constants are an important factor for the fabrication of anodic porous alumina films.

Processing of copper anodic-slimes for extraction of valuable metals.

Science.gov (United States)

Amer, A M

2003-01-01

This work focuses on processing of anodic slimes obtained from an Egyptian copper electrorefining plant. The anodic slimes are characterized by high concentrations of copper, lead, tin and silver. The proposed hydrometallurgical process consists of two leaching stages for the extraction of copper (H(2)SO(4)-O(2)) and silver (thiourea-Fe3+), and pyrometallurgical treatment of the remaining slimes for production of Pb-Sn soldering alloy. Factors affecting both the leaching and smelting stages were studied.

Composition, structure and electrical properties of alumina barrier layers grown in fluoride-containing oxalic acid solutions

Energy Technology Data Exchange (ETDEWEB)

Jagminas, A. [Institute of Chemistry, A. Gostauto 9, LT-01108 Vilnius (Lithuania)], E-mail: jagmin@ktl.mii.lt; Vrublevsky, I. [Department of Microelectricals, Belarusian State University of Informatics and Radioelectricals, 6 Brovka Street, Minsk 220013 (Belarus); Kuzmarskyte, J.; Jasulaitiene, V. [Institute of Chemistry, A. Gostauto 9, LT-01108 Vilnius (Lithuania)

2008-04-15

The composition, structure and electrical properties of alumina barrier layers grown by anodic oxidation in F{sup -}-containing (FC) and F{sup -}-free (FF) oxalic acid solutions were studied using the re-anodizing/dissolution technique, Fourier-transformed infrared and X-ray photoelectron spectroscopy. These results confirmed formation in FC anodizing solutions of films structurally different from ones grown in FF oxalic acid baths. It was found that the barrier layer of FC alumina films is composed of two layers differing in the dissolution rate. These differences are related to the formation in the FC electrolyte of a barrier layer composed of a more microporous outer part and a thin, non-porous and non-scalloped inner part consisting of aluminum oxide and aluminum fluoride.

Conductive Polymeric Binder for Lithium-Ion Battery Anode

Science.gov (United States)

Gao, Tianxiang

Tin (Sn) has a high-specific capacity (993 mAhg-1) as an anode material for Li-ion batteries. To overcome the poor cycling performance issue caused by its large volume expansion and pulverization during the charging and discharging process, many researchers put efforts into it. Most of the strategies are through nanostructured material design and introducing conductive polymer binders that serve as matrix of the active material in anode. This thesis aims for developing a novel method for preparing the anode to improve the capacity retention rate. This would require the anode to have high electrical conductivity, high ionic conductivity, and good mechanical properties, especially elasticity. Here the incorporation of a conducting polymer and a conductive hydrogel in Sn-based anodes using a one-step electrochemical deposition via a 3-electrode cell method is reported: the Sn particles and conductive component can be electrochemically synthesized and simultaneously deposited into a hybrid thin film onto the working electrode directly forming the anode. A well-defined three dimensional network structure consisting of Sn nanoparticles coated by conducting polymers is achieved. Such a conductive polymer-hydrogel network has multiple advantageous features: meshporous polymeric structure can offer the pathway for lithium ion transfer between the anode and electrolyte; the continuous electrically conductive polypyrrole network, with the electrostatic interaction with elastic, porous hydrogel, poly (2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile) (PAMPS) as both the crosslinker and doping anion for polypyrrole (PPy) can decrease the volume expansion by creating porous scaffold and softening the system itself. Furthermore, by increasing the amount of PAMPS and creating an interval can improve the cycling performance, resulting in improved capacity retention about 80% after 20 cycles, compared with only 54% of that of the control sample without PAMPS. The cycle

The Roles of Biofilm Conductivity and Donor Substrate Kinetics in a Mixed-Culture Biofilm Anod

Science.gov (United States)

We experimentally assessed kinetics and thermodynamics of electron transfer (ET) from the donor substrate (acetate) to the anode for a mixed-culture biofilm anode. We interpreted the results with a modified biofilm-conduction model consisting of three ET steps: (1) intracellular...

Electrochemical degradation of diuron in chloride medium using DSA Registered-Sign based anodes

Energy Technology Data Exchange (ETDEWEB)

Pipi, Angelo R. F.; Aquino Neto, Sidney; Andrade, Adalgisa R. de, E-mail: ardandra@ffclrp.usp.br [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto-SP (Brazil)

2013-07-15

This work presents a study of the electrochemical degradation of the herbicide diuron using Ti/Ru{sub x}Ti{sub (1-x)}O{sub 2} and Ti/Ir{sub x}Ti{sub (1-x)}O{sub 2} (x 0.3, 0.5 and 0.7) anodes. The investigation of the degradation was conducted in the presence and in the absence of chloride. The study of the herbicide removal as a function of the current density in the absence of chloride yielded 41 and 49% COD (chemical oxygen demand) removals and 10 and 14% TOC (total organic carbon) removal at 100 mA cm{sup -2}, respectively. By keeping the electrolysis time constant (4 h), Ti/Ru{sub 0.7}Ti{sub 0.3}O{sub 2} anode composition was determined as the most active for removal of diuron and its byproduct. The maximum removal value achieved after 4 h was 58%. Addition of chloride doubled the removal ratio, and 100% COD removal was obtained for Ti/Ru{sub 0.3}Ti{sub 0.7}O{sub 2} . High-performance liquid chromatography (HPLC) analysis confirmed the total removal of the herbicide in chloride medium and indicated the formation of byproducts. The generated byproducts presented as function of the applied current density and the anode composition. Ir-based anodes promoted milder oxidation and furnished more byproducts in aqueous medium. (author)

Electrical and stability performance of anode-supported solid oxide fuel cells with strontium- and magnesium-doped lanthanum gallate thin electrolyte

International Nuclear Information System (INIS)

Guo Weimin; Liu Jiang; Zhang Yaohui

2008-01-01

Anode-supported solid oxide fuel cells (SOFCs) comprising NiO-samarium-doped ceria (SDC) (Sm 0.2 Ce 0.8 O 1.9 ) composite anode, thin tri-layer electrolyte, and La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 (LSCF)-La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ (LSGM) composite cathode were fabricated. The thin tri-layer consisting of an 11-μm thick LSGM electrolyte layer and a 12-μm thick La 0.4 Ce 0.6 O 1.8 (LDC) layer on each side of the LSGM was prepared by centrifugal casting and co-firing technique. The performance of the cells operated with humidified H 2 as fuel and ambient air as oxidant showed a maximum power density of 1.23 W cm -2 at 800 deg. C. A stability test of about 100 h was carried out and some deterioration of output power was observed, while the open circuit voltage (OCV) kept unchanged. Impedance measurements showed that both the electrolyte ohmic resistance and the electrode polarization increased with time and the latter dominated the degradation

Effect of anodizing voltage on the sorption of water molecules on porous alumina

Energy Technology Data Exchange (ETDEWEB)

Vrublevsky, I., E-mail: vrublevsky@bsuir.edu.by [Belarusian State University of Informatics and Radioelectronics, Department of Micro and Nanoelectronics, 220013 Minsk (Belarus); Chernyakova, K. [Belarusian State University of Informatics and Radioelectronics, Department of Micro and Nanoelectronics, 220013 Minsk (Belarus); Bund, A.; Ispas, A.; Schmidt, U. [Fachgebiet Elektrochemie und Galvanotechnik, Technische Universitaet Ilmenau, 98693 Ilmenau (Germany)

2012-05-01

The amount of water adsorbed on different centers on the surface of oxalic acid alumina films is a function of the anodizing voltage. It is decreased with increasing the anodizing voltage from 20 up to 50 V, came up to maximum value at 20-30 V and slightly increased at voltages above 50 V. Water adsorption by oxide films formed at voltages below 50 V can be due to the negative surface charge that is present on the alumina surface. The negative surface charge disappears in the films formed at voltages higher than 50 V, and thus, the water is adsorbed on aluminum ions in a tetrahedral and octahedral environment. The correlation between anodizing conditions of aluminum in oxalic acid and the structure and composition of anodic alumina was established by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), thermogravimetric and differential thermal analyses (TG/DTA).

Anodized dental implant surface

Directory of Open Access Journals (Sweden)

Sunil Kumar Mishra

2017-01-01

Full Text Available Purpose: Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. Materials and Methods: A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. Results: The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. Conclusions: The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

A Combined Self-Consistent Method to Estimate the Effective Properties of Polypropylene/Calcium Carbonate Composites

Directory of Open Access Journals (Sweden)

Zhongqiang Xiong

2018-01-01

Full Text Available In this work, trying to avoid difficulty of application due to the irregular filler shapes in experiments, self-consistent and differential self-consistent methods were combined to obtain a decoupled equation. The combined method suggests a tenor γ independent of filler-contents being an important connection between high and low filler-contents. On one hand, the constant parameter can be calculated by Eshelby’s inclusion theory or the Mori–Tanaka method to predict effective properties of composites coinciding with its hypothesis. On the other hand, the parameter can be calculated with several experimental results to estimate the effective properties of prepared composites of other different contents. In addition, an evaluation index σ f ′ of the interactional strength between matrix and fillers is proposed based on experiments. In experiments, a hyper-dispersant was synthesized to prepare polypropylene/calcium carbonate (PP/CaCO3 composites up to 70 wt % of filler-content with dispersion, whose dosage was only 5 wt % of the CaCO3 contents. Based on several verifications, it is hoped that the combined self-consistent method is valid for other two-phase composites in experiments with the same application progress as in this work.

Anode-supported SOFC operated under single-chamber conditions at intermediate temperatures

Energy Technology Data Exchange (ETDEWEB)

Morales, M.; Roa, J.J.; Segarra, M. [Department of Materials Science and Metallurgical Engineering, University of Barcelona, E-08028, Barcelona (Spain); Capdevila, X.G. [Center of Design and Optimization in Avanced Materials, Parc Cientific of Barcelona, E-08028, Barcelona (Spain); Pinol, S. [Institute of Materials Science of Barcelona (CSIC), Campus of the UAB, Bellaterra E-08193, Barcelona (Spain)

2011-02-15

Anode-supported SOFC was fabricated using gadolinia doped ceria (GDC) as the electrolyte (15 {mu}m of thickness), Ni-GDC as the anode and La{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}}-GDC as the cathode. Catalytic activities of the electrodes and electrical properties of the cell were determined, using mixtures of methane + air, under single-chamber conditions. This work assessed with special and wide emphasis the effect of temperature, gas composition and total flow rate on the cell performance. As a result, operational temperature range of the fuel cell was approximately between 700 and 800 C, which agrees with the results corresponding to the catalytic activities of electrodes. While Ni-GDC anode was enough active towards methane partial oxidation at cell temperatures higher than 700 C, the LSC-GDC cathode was enough inactive towards partial and total oxidation of methane at cell temperatures lower than 800 C. Under optimised gas compositions (CH{sub 4}/O{sub 2}) ratio (1) and total flow rate (530 mL min {sup -1}), power densities of 145 and 235 mW cm {sup -2} were obtained at 705 and 764 C, respectively. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Chemical compatibility and properties of suspension plasma-sprayed SrTiO3-based anodes for intermediate-temperature solid oxide fuel cells

Science.gov (United States)

Zhang, Shan-Lin; Li, Cheng-Xin; Li, Chang-Jiu

2014-10-01

La-doped strontium titanate (LST) is a promising, redox-stable perovskite material for direct hydrocarbon oxidation anodes in intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this study, nano-sized LST and Sm-doped ceria (SDC) powders are produced by the sol-gel and glycine-nitrate processes, respectively. The chemical compatibility between LST and electrolyte materials is studied. A LST-SDC composite anode is prepared by suspension plasma spraying (SPS). The effects of annealing conditions on the phase structure, microstructure, and chemical stability of the LST-SDC composite anode are investigated. The results indicate that the suspension plasma-sprayed LST-SDC anode has the same phase structure as the original powders. LST exhibits a good chemical compatibility with SDC and Mg/Sr-doped lanthanum gallate (LSGM). The anode has a porosity of ∼40% with a finely porous structure that provides high gas permeability and a long three-phase boundary for the anode reaction. Single cells assembled with the LST-SDC anode, La0.8Sr0.2Ga0.8Mg0.2O3 electrolyte, and La0.8Sr0.2CoO3-SDC cathode show a good performance at 650-800 °C. The annealing reduces the impedances due to the enhancement in the bonding between the particles in the anode and interface of anode and LSGM electrolyte, thus improving the output performance of the cell.

Atomic Layer Deposition of SnO2 on MXene for Li-Ion Battery Anodes

KAUST Repository

Ahmed, Bilal

2017-02-24

In this report, we show that oxide battery anodes can be grown on two-dimensional titanium carbide sheets (MXenes) by atomic layer deposition. Using this approach, we have fabricated a composite SnO2/MXene anode for Li-ion battery applications. The SnO2/MXene anode exploits the high Li-ion capacity offered by SnO2, while maintaining the structural and mechanical integrity by the conductive MXene platform. The atomic layer deposition (ALD) conditions used to deposit SnO2 on MXene terminated with oxygen, fluorine, and hydroxyl-groups were found to be critical for preventing MXene degradation during ALD. We demonstrate that SnO2/MXene electrodes exhibit excellent electrochemical performance as Li-ion battery anodes, where conductive MXene sheets act to buffer the volume changes associated with lithiation and delithiation of SnO2. The cyclic performance of the anodes is further improved by depositing a very thin passivation layer of HfO2, in the same ALD reactor, on the SnO2/MXene anode. This is shown by high-resolution transmission electron microscopy to also improve the structural integrity of SnO2 anode during cycling. The HfO2 coated SnO2/MXene electrodes demonstrate a stable specific capacity of 843 mAh/g when used as Li-ion battery anodes.

Influence of molybdate species on the tartaric acid/sulphuric acid anodic films grown on AA2024 T3 aerospace alloy

Energy Technology Data Exchange (ETDEWEB)

Garcia-Rubio, M. [Departamento de Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Department of Surface Technologies, Engineering of Materials and Processes, Airbus Spain, Av. John Lennon s/n 28906 Getafe (Spain); Ocon, P. [Departamento de Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, 28049 Madrid (Spain)], E-mail: pilar.ocon@uam.es; Climent-Font, A. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid (UAM), 28049 Madrid (Spain); Centro de Micro-Analisis de Materiales (CMAM), Universidad Autonoma de Madrid (UAM), 28049 Madrid (Spain); Smith, R.W. [Unidad de Microanalisis de Materiales, Parque Cientifico de Madrid (PCM), Campus de Cantoblanco, 28049 Madrid (Spain); Curioni, M.; Thompson, G.E.; Skeldon, P. [Corrosion and Protection Centre, School of Materials, University of Manchester, M60 1QD England (United Kingdom); Lavia, A.; Garcia, I. [Department of Surface Technologies, Engineering of Materials and Processes, Airbus Spain, Av. John Lennon s/n 28906 Getafe (Spain)

2009-09-15

AA2024 T3 alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.

Influence of molybdate species on the tartaric acid/sulphuric acid anodic films grown on AA2024 T3 aerospace alloy

International Nuclear Information System (INIS)

Garcia-Rubio, M.; Ocon, P.; Climent-Font, A.; Smith, R.W.; Curioni, M.; Thompson, G.E.; Skeldon, P.; Lavia, A.; Garcia, I.

2009-01-01

AA2024 T3 alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.

Effect of hydrogen on stresses in anodic oxide film on titanium

International Nuclear Information System (INIS)

Kim, Joong-Do; Pyun, Su-Il; Seo, Masahiro

2003-01-01

Stresses in anodic oxide film on titanium thin film/glass electrode in pH 8.4 borate solution were investigated by a bending beam method. The increases in compressive stress observed with cathodic potential sweeps after formation of anodic oxide film were attributed to the volume expansion due to the compositional change of anodic oxide film from TiO 2 to TiO 2-x (OH) x . The instantaneous responses of changes in stress, Δσ, in the anodic oxide film to potential steps demonstrated the reversible characteristic of the TiO 2-x (OH) x formation reaction. In contrast, the transient feature of Δσ for the titanium without anodic oxide film represented the irreversible formation of TiH x at the metal/oxide interphase. The large difference in stress between with and without the oxide film, has suggested that most of stresses generated during the hydrogen absorption/desorption reside in the anodic oxide film. A linear relationship between changes in stress, Δ(Δσ) des , and electric charge, ΔQ des , during hydrogen desorption was found from the current and stress transients, manifesting that the stress changes were crucially determined by the amount of hydrogen desorbed from the oxide film. The increasing tendency of -Δ(Δσ) des with increasing number of potential steps and film formation potential were discussed in connection with the increase in desorption amount of hydrogen in the oxide film with increasing absorption/desorption cycles and oxide film thickness

High capacity anode materials for lithium ion batteries

Science.gov (United States)

Lopez, Herman A.; Anguchamy, Yogesh Kumar; Deng, Haixia; Han, Yongbon; Masarapu, Charan; Venkatachalam, Subramanian; Kumar, Suject

2015-11-19

High capacity silicon based anode active materials are described for lithium ion batteries. These materials are shown to be effective in combination with high capacity lithium rich cathode active materials. Supplemental lithium is shown to improve the cycling performance and reduce irreversible capacity loss for at least certain silicon based active materials. In particular silicon based active materials can be formed in composites with electrically conductive coatings, such as pyrolytic carbon coatings or metal coatings, and composites can also be formed with other electrically conductive carbon components, such as carbon nanofibers and carbon nanoparticles. Additional alloys with silicon are explored.

Yolk-shell structured Sb@C anodes for high energy Na-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Song, Junhua; Yan, Pengfei; Luo, Langli; Qi, Xingguo; Rong, Xiaohui; Zheng, Jianming; Xiao, Biwei; Feng, Shuo; Wang, Chongmin; Hu, Yong-Sheng; Lin, Yuehe; Sprenkle, Vincent L.; Li, Xiaolin

2017-10-01

Despite great advances in sodium-ion battery developments, the search for high energy and stable anode materials remains a challenge. Alloy or conversion-typed anode materials are attractive candidates of high specific capacity and low voltage potential, yet their applications are hampered by the large volume expansion and hence poor electrochemical reversibility and fast capacity fade. Here, we use antimony (Sb) as an example to demonstrate the use of yolk-shell structured anodes for high energy Na-ion batteries. The Sb@C yolk-shell structure prepared by controlled reduction and selective removal of Sb2O3 from carbon coated Sb2O3 nanoparticles can accommodate the Sb swelling upon sodiation and improve the structural/electrical integrity against pulverization. It delivers a high specific capacity of ~554 mAh•g-1, good rate capability (315 mhA•g-1 at 10C rate) and long cyclability (92% capacity retention over 200 cycles). Full-cells of O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2 cathodes and Sb@C-hard carbon composite anodes demonstrate a high specific energy of ~130 Wh•kg-1 (based on the total mass of cathode and anode) in the voltage range of 2.0-4.0 V, ~1.5 times energy of full-cells with similar design using hard carbon anodes.

Light-Weight Free-Standing Carbon Nanotube-Silicon Films for Anodes of Lithium Ion Batteries

KAUST Repository

Cui, Li-Feng

2010-07-27

Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the infiltrated CNT network functions as both mechanical support and electrical conductor and Si as a high capacity anode material for Li-ion battery. Such free-standing film has a low sheet resistance of ∼30 Ohm/sq. It shows a high specific charge storage capacity (∼2000 mAh/g) and a good cycling life, superior to pure sputtered-on silicon films with similar thicknesses. Scanning electron micrographs show that Si is still connected by the CNT network even when small breaking or cracks appear in the film after cycling. The film can also "ripple up" to release the strain of a large volume change during lithium intercalation. The conductive composite film can function as both anode active material and current collector. It offers ∼10 times improvement in specific capacity compared with widely used graphite/copper anode sheets. © 2010 American Chemical Society.

Confined SnO2 quantum-dot clusters in graphene sheets as high-performance anodes for lithium-ion batteries.

Science.gov (United States)

Zhu, Chengling; Zhu, Shenmin; Zhang, Kai; Hui, Zeyu; Pan, Hui; Chen, Zhixin; Li, Yao; Zhang, Di; Wang, Da-Wei

2016-05-16

Construction of metal oxide nanoparticles as anodes is of special interest for next-generation lithium-ion batteries. The main challenge lies in their rapid capacity fading caused by the structural degradation and instability of solid-electrolyte interphase (SEI) layer during charge/discharge process. Herein, we address these problems by constructing a novel-structured SnO2-based anode. The novel structure consists of mesoporous clusters of SnO2 quantum dots (SnO2 QDs), which are wrapped with reduced graphene oxide (RGO) sheets. The mesopores inside the clusters provide enough room for the expansion and contraction of SnO2 QDs during charge/discharge process while the integral structure of the clusters can be maintained. The wrapping RGO sheets act as electrolyte barrier and conductive reinforcement. When used as an anode, the resultant composite (MQDC-SnO2/RGO) shows an extremely high reversible capacity of 924 mAh g(-1) after 200 cycles at 100 mA g(-1), superior capacity retention (96%), and outstanding rate performance (505 mAh g(-1) after 1000 cycles at 1000 mA g(-1)). Importantly, the materials can be easily scaled up under mild conditions. Our findings pave a new way for the development of metal oxide towards enhanced lithium storage performance.

The anodization synthesis of copper oxide nanosheet arrays and their photoelectrochemical properties

Energy Technology Data Exchange (ETDEWEB)

Shu, Xia [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zheng, Hongmei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Xu, Guangqing, E-mail: gqxu1979@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Zhao, Jiebo [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Cui, Lihua [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Materials Science and Engineering, Beifang University of Nationalities, Yinchuan 750021 (China); Cui, Jiewu; Qin, Yongqiang; Wang, Yan [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Yong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Wu, Yucheng, E-mail: ycwu@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China)

2017-08-01

Graphical abstract: Current-time and potential-time curves of the copper foil anodization process, CV of copper substrate in anodization solution and SEM morphologies of anodization products on Cu substrates obtained at different time. - Highlights: • Copper oxides nanosheet arrays were achieved via anodization method. • The growth mechanisms of the copper anodization process were studied. • Photoelectrochemical performances of copper oxides NSAs were studied. - Abstract: We studied the growth of copper oxide nanosheet arrays on copper foil via a simple anodization method. The structures, morphologies, and elemental compositions of the specimens were characterized with an X-ray diffractometer, scanning electron microscope, high resolution transmission electron microscope, and X-ray photoelectron spectrometer. The copper oxide (Cu{sub 2}O and CuO) nanosheet arrays were comprised of 30-nm-thick nanosheets that stand vertically on the Cu substrate. The anodizing parameters, such as the current density, temperature, and polyethylene glycol concentration, were optimized to obtain the regular nanosheet arrays. The optical absorption properties of the anodized products were evaluated using a diffuse reflectance spectrometer, and broad and strong optical absorption bands arising from the UV to visible region were observed. The photoelectrochemical performance of the nanosheet arrays was measured with chronoamperometry and cyclic voltammetry on an electrochemical workstation equipped with a Xe lamp (wavelength >400 nm). A negative photocurrent was obtained due to the p-type semiconductor of the copper oxides. The copper oxide nanosheet arrays achieve the highest photocurrent of 0.4 mA/cm{sup 2} at the current density of 1.0 A/dm{sup 2}, temperature of 70 °C, and polyethylene glycol concentration of 0.5 g/L.

Fabrication of a novel aluminum surface covered by numerous high-aspect-ratio anodic alumina nanofibers

Science.gov (United States)

Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

2015-11-01

The formation behavior of anodic alumina nanofibers via anodizing in a concentrated pyrophosphoric acid under various conditions was investigated using electrochemical measurements and SEM/TEM observations. Pyrophosphoric acid anodizing at 293 K resulted in the formation of numerous anodic alumina nanofibers on an aluminum substrate through a thin barrier oxide and honeycomb oxide with narrow walls. However, long-term anodizing led to the chemical dissolution of the alumina nanofibers. The density of the anodic alumina nanofibers decreased as the applied voltage increased in the 10-75 V range. However, active electrochemical dissolution of the aluminum substrate occurred at a higher voltage of 90 V. Low temperature anodizing at 273 K resulted in the formation of long alumina nanofibers measuring several micrometers in length, even though a long processing time was required due to the low current density during the low temperature anodizing. In contrast, high temperature anodizing easily resulted in the formation and chemical dissolution of alumina nanofibers. The structural nanofeatures of the anodic alumina nanofibers were controlled by choosing of the appropriate electrochemical conditions, and numerous high-aspect-ratio alumina nanofibers (>100) can be successfully fabricated. The anodic alumina nanofibers consisted of a pure amorphous aluminum oxide without anions from the employed electrolyte.

Preparation of Si/TiO2 Composite by the Sol-Gel Method Using As the Lithium-Ion Battery Anode

Science.gov (United States)

Wang, Quanwei; Ban, Yueqin; Zhou, Hengwei; Zhang, Lili; Huang, Yineng; Shao, Weiquan; Chen, Shaou

2017-10-01

Si was a promising anode material for next-generation LIBs due to its extremely large capacity of 4200mAh/g (Li4.4Si phase). However, during repeated lithium insertion/extraction processes, the accompanied huge volume change (400%) induced the structural failure of the active material and resulted in rapid capacity fading. To overcome this problem, Si/TiO2 composite with different mole ratio were prepared by the sol-gel method. The inclusion of TiO2 not only worked as a stable electric conductive pathway but also buffered the volume expansion of the Si during the process of charging and discharging. The Si/TiO2 composite with different mole ratio of 1:2, 1:3, 1:4 electrode reaches 480mAh/g, 2590mAh/g and 980mAh/g, and it delivered a charge capacity of 461mAh/g, 2510mAh/g and 891mAh/g at the first cycle, corresponding to an initial coulombic efficiency of 96%, 96% and 91%. In contrast, the cell with the pure Si nanoparticle exhibited an initial discharge/charge capacity of 48 and 33mAh/g, respectively, which was much lower than the Si/TiO2 composite electrode.

Lanthanum Nitrate As Electrolyte Additive To Stabilize the Surface Morphology of Lithium Anode for Lithium-Sulfur Battery.

Science.gov (United States)

Liu, Sheng; Li, Guo-Ran; Gao, Xue-Ping

2016-03-01

Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries. However, the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li-S battery. In this work, lanthanum nitrate, as electrolyte additive, is introduced into Li-S battery to stabilize the surface of lithium anode. By introducing lanthanum nitrate into electrolyte, a composite passivation film of lanthanum/lithium sulfides can be formed on metallic lithium anode, which is beneficial to decrease the reducibility of metallic lithium and slow down the electrochemical dissolution/deposition reaction on lithium anode for stabilizing the surface morphology of metallic Li anode in lithium-sulfur battery. Meanwhile, the cycle stability of the fabricated Li-S cell is improved by introducing lanthanum nitrate into electrolyte. Apparently, lanthanum nitrate is an effective additive for the protection of lithium anode and the cycling stability of Li-S battery.

Process of film formation by anodizing AZ91D magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Qian Jiangang; Li Di; Zhang Feng [School of Materials Science and Engineering, Beijing Univ. of Aeronautics and Astronautics (China)

2005-07-01

The kinetics of film-forming process by anodizing AZ91D Mg alloy has been studied by ways of voltage-time and thickness-time curve, and the surface morphology, structure, composition and valence of element, phase constituent of anodic films have been analyzed by SEM, EDS, XPS and XRD respectively. The results show that the film-forming course can be divided into four stages. Formation of dense layer before sparking is the first stage. Formation of porous layer accompanied with a bit of small sparking is the second stage. Porous layer fast growth along with middle sparking is the third stage. Porous layer slowly-growth along with bigger sparking is the fourth stage. The anodic films contains approximately Mg,O,Si and B, which is composed mainly of MgO, MgSiO{sub 3} and Mg{sub 3}B{sub 2}O{sub 6}. (orig.)

Progress in Metal-Supported Axial-Injection Plasma Sprayed Solid Oxide Fuel Cells Using Nanostructured NiO-Y0.15Zr0.85O1.925 Dry Powder Anode Feedstock

Science.gov (United States)

Metcalfe, C.; Harris, J.; Kuhn, J.; Marr, M.; Kesler, O.

2013-06-01

A composite NiO-Y0.15Zr0.85O1.925 (YSZ) agglomerated feedstock having nanoscale NiO and YSZ primary particles was used to fabricate anodes having sub-micrometer structure. These anodes were incorporated into two different metal-supported SOFC architectures, which differ in the order of electrode deposition. The composition of the composite Ni-YSZ anodes is controllable by selection of the agglomerate size fraction and standoff distance, while the porosity is controllable by selection of agglomerate size fraction and addition of a sacrificial pore-forming material. A bi-layer anode was fabricated having a total porosity of 33% for the diffusion layer and 23% porosity for the functional layer. A power density of 630 mW/cm2 was obtained at 750 °C in humidified H2 with cells having the bi-layer anode deposited on the metal support. Cells having the cathode deposited on the metal support showed poor performance due to a significant number of vertical cracks through the electrolyte, allowing excessive gas cross-over between the anode and the cathode compartments.

Study of the phase composition of nanostructures produced by the local anodic oxidation of titanium films

International Nuclear Information System (INIS)

Avilov, V. I.; Ageev, O. A.; Konoplev, B. G.; Smirnov, V. A.; Solodovnik, M. S.; Tsukanova, O. G.

2016-01-01

The results of experimental studies of the phase composition of oxide nanostructures formed by the local anodic oxidation of a titanium thin film are reported. The data of the phase analysis of titanium-oxide nanostructures are obtained by X-ray photoelectron spectroscopy in the ion profiling mode of measurements. It is established that the surface of titanium-oxide nanostructures 4.5 ± 0.2 nm in height possesses a binding energy of core levels characteristic of TiO_2 (458.4 eV). By analyzing the titanium-oxide nanostructures in depth by X-ray photoelectron spectroscopy, the formation of phases with binding energies of core levels characteristic of Ti_2O_3 (456.6 eV) and TiO (454.8 eV) is established. The results can be used in developing the technological processes of the formation of a future electronic-component base for nanoelectronics on the basis of titanium-oxide nanostructures and probe nanotechnologies.

Development of Plasma-Sprayed Molybdenum Carbide-Based Anode Layers with Various Metal Oxides for SOFC

Science.gov (United States)

Faisal, N. H.; Ahmed, R.; Katikaneni, S. P.; Souentie, S.; Goosen, M. F. A.

2015-12-01

Air plasma-sprayed (APS) coatings provide an ability to deposit a range of novel fuel cell materials at competitive costs. This work develops three separate types of composite anodes (Mo-Mo2C/Al2O3, Mo-Mo2C/ZrO2, Mo-Mo2C/TiO2) using a combination of APS process parameters on Hastelloy®X for application in intermediate temperature proton-conducting solid oxide fuel cells. Commercially available carbide of molybdenum powder catalyst (Mo-Mo2C) and three metal oxides (Al2O3, ZrO2, TiO2) was used to prepare three separate composite feedstock powders to fabricate three different anodes. Each of the modified composition anode feedstock powders included a stoichiometric weight ratio of 0.8:0.2. The coatings were characterized by scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, nanoindentation, and conductivity. We report herein that three optimized anode layers of thicknesses between 200 and 300 µm and porosity as high as 20% for Mo-Mo2C/Al2O3 (250-µm thick) and Mo-Mo2C/TiO2 (300 µm thick) and 17% for Mo-Mo2C/ZrO2 (220-µm thick), controllable by a selection of the APS process parameters with no addition of sacrificial pore-forming material. The nanohardness results indicate the upper layers of the coatings have higher values than the subsurface layers in coatings with some effect of the deposition on the substrate. Mo-Mo2C/ZrO2 shows high electrical conductivity.

Effects of an anode sheath on energy and momentum transfer in vacuum arcs

International Nuclear Information System (INIS)

Wang, Zhenxing; Zhou, Zhipeng; Tian, Yunbo; Wang, Haoran; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

2017-01-01

Anode phenomena under high-current vacuum arcs have a significant impact on the interrupting capacity of vacuum interrupters. However, the vacuum arc energy flux and momentum flux on the anode—which are necessary boundary conditions for simulations—are either set to an imaginary distribution or calculated using simple formulas without considering anode sheath regulatory effects. The objective of this paper is to reveal the anode sheath effects on regulating the energy and momentum transfer from the arc column to the anode surface in vacuum arcs. A particle-in-cell model for the anode sheath is developed. The required input parameters are obtained from a magnetohydrodynamic model for the arc column. From the results, there exists a sheath near the anode with a negative voltage drop. Both the electron density and the ion density significantly decline in the anode sheath region. The kinetic energy of the ions absorbed by the anode consists of directed kinetic energy, random kinetic energy, and sheath acceleration energy. The sheath acceleration energy contribution is the largest, and the random kinetic energy also accounts for a large part that cannot be ignored. The arc pressure on the anode surface is mainly caused by ion impact, and the accelerating effect of the anode sheath on the ions cannot be neglected in pressure calculations. In addition, in the case of an arc current at 15 kA, the input energy and momentum upon the anode surface is not obviously affected by the evaporated atoms at surface temperatures of 1600 K and 2000 K. (paper)

Highly ordered porous alumina with tailor-made pore structures fabricated by pulse anodization

International Nuclear Information System (INIS)

Lee, Woo; Kim, Jae-Cheon

2010-01-01

A new anodization method for the preparation of nanoporous anodic aluminum oxide (AAO) with pattern-addressed pore structure was developed. The approach is based on pulse anodization of aluminum employing a series of potential waves that consist of two or more different pulses with designated periods and amplitudes, and provides unique tailoring capability of the internal pore structure of anodic alumina. Pores of the resulting AAOs exhibit a high degree of directional coherency along the pore axes without branching, and thus are suitable for fabricating novel nanowires or nanotubes, whose diameter modulation patterns are predefined by the internal pore geometry of AAO. It is found from microscopic analysis on pulse anodized AAOs that the effective electric field strength at the pore base is a key controlling parameter, governing not only the size of pores, but also the detailed geometry of the barrier oxide layer.

Carbon deposition thresholds on nickel-based solid oxide fuel cell anodes I. Fuel utilization

Science.gov (United States)

Kuhn, J.; Kesler, O.

2015-03-01

In the first of a two part publication, the effect of fuel utilization (Uf) on carbon deposition rates in solid oxide fuel cell nickel-based anodes was studied. Representative 5-component CH4 reformate compositions (CH4, H2, CO, H2O, & CO2) were selected graphically by plotting the solutions to a system of mass-balance constraint equations. The centroid of the solution space was chosen to represent a typical anode gas mixture for each nominal Uf value. Selected 5-component and 3-component gas mixtures were then delivered to anode-supported cells for 10 h, followed by determination of the resulting deposited carbon mass. The empirical carbon deposition thresholds were affected by atomic carbon (C), hydrogen (H), and oxygen (O) fractions of the delivered gas mixtures and temperature. It was also found that CH4-rich gas mixtures caused irreversible damage, whereas atomically equivalent CO-rich compositions did not. The coking threshold predicted by thermodynamic equilibrium calculations employing graphite for the solid carbon phase agreed well with empirical thresholds at 700 °C (Uf ≈ 32%); however, at 600 °C, poor agreement was observed with the empirical threshold of ∼36%. Finally, cell operating temperatures correlated well with the difference in enthalpy between the supplied anode gas mixtures and their resulting thermodynamic equilibrium gas mixtures.

Challenges in Accommodating Volume Change of Si Anodes for Li-Ion Batteries.

Science.gov (United States)

Ko, Minseong; Chae, Sujong; Cho, Jaephil

2015-11-01

Si has been considered as a promising alternative anode for next-generation Li-ion batteries (LIBs) because of its high theoretical energy density, relatively low working potential, and abundance in nature. However, Si anodes exhibit rapid capacity decay and an increase in the internal resistance, which are caused by the large volume changes upon Li insertion and extraction. This unfortunately limits their practical applications. Therefore, managing the total volume change remains a critical challenge for effectively alleviating the mechanical fractures and instability of solid-electrolyte-interphase products. In this regard, we review the recent progress in volume-change-accommodating Si electrodes and investigate their ingenious structures with significant improvements in the battery performance, including size-controlled materials, patterned thin films, porous structures, shape-preserving shell designs, and graphene composites. These representative approaches potentially overcome the large morphologic changes in the volume of Si anodes by securing the strain relaxation and structural integrity in the entire electrode. Finally, we propose perspectives and future challenges to realize the practical application of Si anodes in LIB systems.

The simulation of the temperature effects on the microhardness of anodic alumina oxide layers

Directory of Open Access Journals (Sweden)

M. Gombár

2014-01-01

Full Text Available In order to improve the mechanical properties of the layer deposited by anodic oxidation of aluminum on the material EN AW-1050 H24, in the contribution was investigated the microhardness of the deposited layer as a function of the physic-chemical factors affecting in the process of anodic oxidation at the constant anodic current density J = 3 A.dm-2 in electrolyte formed by sulfuric acid and oxalic acid, with the emphasis on the influence of electrolyte temperature in the range – 1,78 °C to 45,78 °C. The model of the studied dependence was compiled based on mathematical and statistical analysis of matrix from experimental obtained data from composite rotation plan of experiment with five independent variable factors (amount of sulfuric acid in the electrolyte, the amount of oxalic acid in the electrolyte, electrolyte, anodizing time and applied voltage.

Hierarchical structured graphene/metal oxide/porous carbon composites as anode materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Guo, Rong [Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Yue, Wenbo, E-mail: wbyue@bnu.edu.cn [Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Ren, Yu [National Institute of Clean-and-Low-Carbon Energy, Beijing 102209 (China); Zhou, Wuzong [School of Chemistry, University of St. Andrews, St. Andrews, Fite KY16 9ST (United Kingdom)

2016-01-15

Highlights: • CeO{sub 2} and Co{sub 3}O{sub 4} nanoparticles display different behavior within CMK-3. • CMK-3-CeO{sub 2} and Co{sub 3}O{sub 4} show various electrochemical properties • CMK-3-CeO{sub 2} and Co{sub 3}O{sub 4} are further wrapped by graphene nanosheets. • Graphene-encapsulated composites show better electrochemical performances. - Abstract: As a novel anode material for lithium-ion batteries, CeO{sub 2} displays imperceptible volumetric and morphological changes during the lithium insertion and extraction processes, and thereby exhibits good cycling stability. However, the low theoretical capacity and poor electronic conductivity of CeO{sub 2} hinder its practical application. In contrast, Co{sub 3}O{sub 4} possesses high theoretical capacity, but undergoes huge volume change during cycling. To overcome these issues, CeO{sub 2} and Co{sub 3}O{sub 4} nanoparticles are formed inside the pores of CMK-3 and display various electrochemical behaviors due to the different morphological structures of CeO{sub 2} and Co{sub 3}O{sub 4} within CMK-3. Moreover, the graphene/metal oxide/CMK-3 composites with a hierarchical structure are then prepared and exhibit better electrochemical performances than metal oxides with or without CMK-3. This novel synthesis strategy is hopefully employed in the electrode materials design for Li-ion batteries or other energy conversion and storage devices.

Fabrication of Well-Ordered, Anodic Aluminum Oxide Membrane Using Hybrid Anodization.

Science.gov (United States)

Kim, Jungyoon; Ganorkar, Shraddha; Choi, Jinnil; Kim, Young-Hwan; Kim, Seong-II

2017-01-01

Anodic Aluminum Oxide (AAO) is one of the most favorable candidates for fabrication of nano-meshed membrane for various applications due to its controllable pore size and self-ordered structure. The mechanism of AAO membrane is a simple and has been studied by many research groups, however the actual fabrication of membrane has several difficulties owing to its sensitivity of ordering, long anodizing time and unclearness of the pore. In this work, we have demonstrated enhanced process of fabrication symmetric AAO membrane by using “hybrid anodizing” (Hyb-A) method which include mild anodization (MA) followed by hard anodization (HA). This Hyb-A process can give highly ordered membrane with more vivid pore than two-step anodizing process. HA was implemented on the Al plate which has been already textured by MA for more ordered structure and HA plays a key role for formation of more obvious pore in Hyb-A. Our experimental results indicate that Hyb-A with proper process sequence would be one of the fast and useful fabrication methods for the AAO membrane.

Electrically conductive anodized aluminum coatings

Science.gov (United States)

Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

2001-01-01

A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

Electrochemical characterization of anode passivation mechanisms in copper electrorefining

Science.gov (United States)

Moats, Michael Scott

Anode passivation can decrease productivity and quality while increasing costs in modern copper electrorefineries. This investigation utilized electrochemical techniques to characterize the passivation behavior of anode samples from ten different operating companies. It is believed that this collection of anodes is the most diverse set ever to be assembled to study the effect of anode composition on passivation. Chronopotentiometry was the main electrochemical technique, employing a current density of 3820 A m-2. From statistical analysis of the passivation characteristics, increasing selenium, tellurium, silver, lead and nickel were shown to accelerate passivation. Arsenic was the only anode impurity that inhibited passivation. Oxygen was shown to accelerate passivation when increased from 500 to 1500 ppm, but further increases did not adversely affect passivation. Nine electrolyte variables were also examined. Increasing the copper, sulfuric acid or sulfate concentration of the electrolyte accelerated passivation. Arsenic in the electrolyte had no effect on passivation. Chloride and optimal concentrations of thiourea and glue delayed passivation. Linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy provided complementary information. Analysis of the electrochemical results led to the development of a unified passivation mechanism. Anode passivation results from the formation of inhibiting films. Careful examination of the potential details, especially those found in the oscillations just prior to passivation, demonstrated the importance of slimes, copper sulfate and copper oxide. Slimes confine dissolution to their pores and inhibit diffusion. This can lead to copper sulfate precipitation, which blocks more of the surface area. Copper oxide forms because of the resulting increase in potential at the interface between the copper sulfate and anode. Ultimate passivation occurs when the anode potential is high enough to stabilize the oxide film in

Fabrication of sacrificial anode cathodic protection through casting method

International Nuclear Information System (INIS)

Mohd Sharif Sattar; Muhamad Daud; Siti Radiah Mohd Kamarudin; Azali Muhamad; Zaiton Selamat; Rusni Rejab

2007-01-01

Aluminum is one of the few metals that can be cast by all of the processes used in casting metals. These processes consist of die casting, permanent mold casting, sand casting (green sand and dry sand), plaster casting, investment casting, and continuous casting. Other processes such as lost foam, squeeze casting, and hot isostatic pressing are also used. Permanent mold casting method was selected in which used for fabricating of sacrificial anode cathodic protection. This product was ground for surface finished and fabricated in the cylindrical form and reinforced with carbon steel at a center of the anode. (Author)

Recovery Of Valuable Metals In Tin-Based Anodic Slimes By Carbothermic Reaction

Directory of Open Access Journals (Sweden)

Han Chulwoong

2015-06-01

Full Text Available This study investigated the recovery of anodic slimes by carbothermic reaction in the temperature range of 973~1,273K and amount of carbon as a function of time. Tin anodic slime samples were collected from the bottom of the electrolytic cells during the electro-refining of tin. The anodic slimes are consisted of high concentrated tin, silver, copper and lead oxides. The kinetics of reduction were determined by means of the weight-loss measurement technique. In order to understand in detail of carbothermic reaction, thermodynamic calculation was carried out and compared with experiments. From thermodynamic calculation and experiment, it was confirmed that Sn-based anodic slime could be reduced by controlling temperature and amount of carbon. However, any tendency between the reduction temperature and carbon content for the reduction reaction was not observed.

Enhancing hybrid direct carbon fuel cell anode performance using Ag2O

DEFF Research Database (Denmark)

Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

2015-01-01

A hybrid-direct carbon fuel cell (HDCFC), consisting of a molten slurry of solid carbon black and (Li-K)2CO3 added to the anode chamber of a solid oxide fuel cell, was characterized using current-potential-power density curves, electrochemical impedance spectroscopy, and cyclic voltammetry. Two...... types of experimental setups were employed in this study, an anode-supported full cell configuration (two electrodes, two atmospheres setup) and a 3-electrode electrolyte-supported half-cell setup (single atmosphere). Anode processes with and without catalysts were investigated as a function...... of temperature (700-800 °C) and anode sweep gas (N2, 4-100% CO2 in N2-CO2). It was shown that the addition of silver based catalysts (Ag, Ag2O, Ag2CO3) into the carbon-carbonate slurry enhanced the performance of the HDCFC....

Process for anodizing aluminum foil

International Nuclear Information System (INIS)

Ball, J.A.; Scott, J.W.

1984-01-01

In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 80 0 C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V

Resistometric studies of anodic dissolution and passivation of chromium in weakly acid solutions

International Nuclear Information System (INIS)

Shlepakov, M.N.; Sukhotin, A.M.

1984-01-01

The method of calculating the rate of Cr anodic solution according to the change of electric resistance of chromium anodes under the effect of potentiostatic polarization, is applied. The maximum corresponding to ranges of active-passive transition is absent in weakly acid solutions with pH>3. The range of existence of active-passive transition is expanded to pH approximately 5.2. The existence of a dissolving section in Cr in the chemical mechanism is proved. Cr passivation mechanism with the formation of passivating oxide of a complex composition is suggested

For cermet inert anode containing oxide and metal phases useful for the electrolytic production of metals

Science.gov (United States)

Ray, Siba P.; Liu, Xinghua; Weirauch, Douglas A.

2002-01-01

A cermet inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode comprises a ceramic phase including an oxide of Ni, Fe and M, where M is at least one metal selected from Zn, Co, Al, Li, Cu, Ti, V, Cr, Zr, Nb, Ta, W, Mo, Hf and rare earths, preferably Zn and/or Co. Preferred ceramic compositions comprise Fe.sub.2 O.sub.3, NiO and ZnO or CoO. The cermet inert anode also comprises a metal phase such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. A preferred metal phase comprises Cu and Ag. The cermet inert anodes may be used in electrolytic reduction cells for the production of commercial purity aluminum as well as other metals.

Quantitative relationship between nanotube length and anodizing current during constant current anodization

International Nuclear Information System (INIS)

Zhang, Yulian; Cheng, Weijie; Du, Fei; Zhang, Shaoyu; Ma, Weihua; Li, Dongdong; Song, Ye; Zhu, Xufei

2015-01-01

Highlights: • Ti anodization was performed by constant current rather than constant voltage. • The nanotube length was controlled by ionic current rather than dissolution current. • Electronic current can be estimated by the nanotube length and the anodizing current. • Dissolution reaction hardly contributes electric current across the barrier layer. - Abstract: The growth kinetics of anodic TiO 2 nanotubes (ATNTs) still remains unclear. ATNTs are generally fabricated under potentiostatic conditions rather than galvanostatic ones. The quantitative relationship between nanotube length and anodizing current (J total ) is difficult to determine, because the variable J total includes ionic current (J ion ) (also called oxide growth current J grow =J ion ) and electronic current (J e ), which cannot be separated from each other. One successful approach to achieve this objective is to use constant current anodization rather than constant voltage anodization, that is, through quantitative comparison between the nanotube length and the known J total during constant current anodization, we can estimate the relative magnitudes of J grow and J e . The nanotubes with lengths of 1.24, 2.23, 3.51 and 4.70 μm, were formed under constant currents (J total ) of 15, 20, 25 and 30 mA, respectively. The relationship between nanotube length (y) and anodizing current (x =J total =J grow +J e ) can be expressed by a fitting equation: y=0.23(x-10.13), from which J grow (J grow = x -10.13) and J e (∼10.13 mA) could be inferred under the present conditions. Meanwhile, the same conclusion could also be deduced from the oxide volume data. These results indicate that the nanotube growth is attributed to the oxide growth current rather than the dissolution current.

Self-ordering behavior of nanoporous anodic aluminum oxide (AAO) in malonic acid anodization

International Nuclear Information System (INIS)

Lee, W; Nielsch, K; Goesele, U

2007-01-01

The self-ordering behavior of anodic aluminum oxide (AAO) has been investigated for anodization of aluminum in malonic acid (H 4 C 3 O 4 ) solution. In the present study it is found that a porous oxide layer formed on the surface of aluminum can effectively suppress catastrophic local events (such as breakdown of the oxide film and plastic deformation of the aluminum substrate), and enables stable fast anodic oxidation under a high electric field of 110-140 V and ∼100 mA cm -2 . Studies on the self-ordering behavior of AAO indicated that the cell homogeneity of AAO increases dramatically as the anodization voltage gets higher than 120 V. Highly ordered AAO with a hexagonal arrangement of the nanopores could be obtained in a voltage range 125-140 V. The current density (i.e., the electric field strength (E) at the bottom of a pore) is an important parameter governing the self-ordering of the nanopores as well as the interpore distance (D int ) for a given anodization potential (U) during malonic acid anodization

A novel compensation method for the anode gain non-uniformity of multi-anode photomultiplier tubes.

Science.gov (United States)

Lee, Chan Mi; Il Kwon, Sun; Ko, Guen Bae; Ito, Mikiko; Yoon, Hyun Suk; Lee, Dong Soo; Hong, Seong Jong; Lee, Jae Sung

2012-01-07

The position-sensitive multi-anode photomultiplier tube (MA-PMT) is widely used in high-resolution scintillation detectors. However, the anode gain nonuniformity of this device is a limiting factor that degrades the intrinsic performance of the detector module. The aim of this work was to develop a gain compensation method for the MA-PMT and evaluate the resulting enhancement in the performance of the detector. The method employs a circuit that is composed only of resistors and is placed between the MA-PMT and a resistive charge division network (RCN) used for position encoding. The goal of the circuit is to divide the output current from each anode, so the same current flows into the RCN regardless of the anode gain. The current division is controlled by the combination of a fixed-value series resistor with an output impedance that is much larger than the input impedance of the RCN, and a parallel resistor, which detours part of the current to ground. PSpice simulations of the compensation circuit and the RCN were performed to determine optimal values for the compensation resistors when used with Hamamatsu H8500 MAPMTs. The intrinsic characteristics of a detector module consisting of this MA-PMT and a lutetium-gadolinium-oxyorthosilicate (LGSO) crystal array were tested with and without the gain compensation method. In simulation, the average coefficient of variation and max/min ratio decreased from 15.7% to 2.7% and 2.0 to 1.2, respectively. In the flood map of the LGSO-H8500 detector, the uniformity of the photopeak position for individual crystals and the energy resolution were much improved. The feasibility of the method was shown by applying it to an octagonal prototype positron emission tomography scanner.

Incorporation of transition metal ions and oxygen generation during anodizing of aluminium alloys

International Nuclear Information System (INIS)

Habazaki, H.; Konno, H.; Shimizu, K.; Nagata, S.; Skeldon, P.; Thompson, G.E.

2004-01-01

Enrichment of nickel at the alloy/film interface and incorporation of nickel species into the anodic film have been examined for a sputtering-deposited Al-1.2at.%Ni alloy in order to assist understanding of oxygen generation in barrier anodic alumina films. Anodizing of the alloy proceeds in two stages similarly to other dilute aluminium alloys, for example Al-Cr and Al-Cu alloys, where the Gibbs free energies per equivalent for formation of alloying element oxide exceeds the value for alumina. In the first stage, a nickel-free alumina film is formed, with nickel enriching in an alloy layer, 2 nm thick, immediately beneath the anodic oxide film. In the second stage, nickel atoms are oxidized together with aluminium, with oxygen generation forming gas bubbles within the anodic oxide film. This stage commences after accumulation of about 5.4 x 10 15 nickel atoms cm -2 in the enriched alloy layer. Oxygen generation also occurs when a thin layer of the alloy, containing about 2.0 x 10 19 nickel atoms m -2 , on electropolished aluminium, is completely anodized, contrasting with thin Al-Cr and Al-Cu alloy layers on electropolished aluminium, for which oxygen generation is essentially absent. A mechanism of oxygen generation, based on electron impurity levels of amorphous alumina and local oxide compositions, is discussed in order to explain the observations

SiC Nanofibers as Long-Life Lithium-Ion Battery Anode Materials

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Xuejiao Sun

2018-05-01

Full Text Available The development of high energy lithium-ion batteries (LIBs has spurred the designing and production of novel anode materials to substitute currently commercial using graphitic materials. Herein, twisted SiC nanofibers toward LIBs anode materials, containing 92.5 wt% cubic β-SiC and 7.5 wt% amorphous C, were successfully synthesized from resin-silica composites. The electrochemical measurements showed that the SiC-based electrode delivered a stable reversible capacity of 254.5 mAh g−1 after 250 cycles at a current density of 0.1 A g−1. It is interesting that a high discharge capacity of 540.1 mAh g−1 was achieved after 500 cycles at an even higher current density of 0.3 A g−1, which is higher than the theoretical capacity of graphite. The results imply that SiC nanomaterials are potential anode candidate for LIBs with high stability due to their high structure stability as supported with the transmission electron microscopy images.

SiC Nanofibers as Long-Life Lithium-Ion Battery Anode Materials.

Science.gov (United States)

Sun, Xuejiao; Shao, Changzhen; Zhang, Feng; Li, Yi; Wu, Qi-Hui; Yang, Yonggang

2018-01-01

The development of high energy lithium-ion batteries (LIBs) has spurred the designing and production of novel anode materials to substitute currently commercial using graphitic materials. Herein, twisted SiC nanofibers toward LIBs anode materials, containing 92.5 wt% cubic β-SiC and 7.5 wt% amorphous C, were successfully synthesized from resin-silica composites. The electrochemical measurements showed that the SiC-based electrode delivered a stable reversible capacity of 254.5 mAh g -1 after 250 cycles at a current density of 0.1 A g -1 . It is interesting that a high discharge capacity of 540.1 mAh g -1 was achieved after 500 cycles at an even higher current density of 0.3 A g -1 , which is higher than the theoretical capacity of graphite. The results imply that SiC nanomaterials are potential anode candidate for LIBs with high stability due to their high structure stability as supported with the transmission electron microscopy images.

X-ray spectral determination of chemical state of phosphorus and sulfur in anodic oxide films on niobium

International Nuclear Information System (INIS)

Bokij, L.P.; Kostikov, Yu.P.

1989-01-01

Chemical forms of phosphorus and sulfur in niobium oxide anodic film, obtained by electrochemical technique using niobium in H 2 SO 4 and H 3 PO 4 aqueous solutions, are determined using data on chemical shifts of X-ray emission lines. Films represent Nb 2 O 5(1-γ) (SO 4 ) 5γ and Nb 2 O 5(1-γ) (PO 4 ) 10γ/3 (γ -share of oxygen substituted by acid anion) composition oxosalts. Electrolyte role in formation of niobium anodic oxide structure and effect of phosphorus and sulfur compounds on anodic film conductivity are determined

Structural study of anodic films formed on aluminum in nitric acid electrolyte

Energy Technology Data Exchange (ETDEWEB)

Yakovleva, N.M.; Anicai, L.; Yakovlev, A.N.; Dima, L.; Khanina, E.Ya.; Buda, M.; Chupakhina, E.A

2002-09-02

The paper presents the results of investigations of porous Al anodic films formed in HNO{sub 3} electrolytes carried out by means of electrochemical techniques and X-ray diffraction as well as scanning electron microscopy (SEM). It was assumed that both electrochemical formation of a porous oxide and anodic dissolution of metal take place at Al/oxide interface at the same time. The analysis of short-range order (SRO) parameters for relatively high current density, 1x10{sup 3} A/m{sup 2}, and anodizing time, 10 min, leads to the conclusion that films mainly consist of amorphous alumina with {gamma}'-Al{sub 2}O{sub 3}-like SRO and a small amount ({approx}10%) of amorphous aluminum oxyhydroxide. SEM investigation of the films revealed strong dependence of the surface relief on different applied forming conditions. This marked change in the surface relief is discussed taking into account the relatively complex behavior of Al during anodization in HNO{sub 3} electrolytes, that involves both electrochemical growth and dissolution processes of anodic film associated with an electrochemical dissolution of aluminum substrate.

Structural study of anodic films formed on aluminum in nitric acid electrolyte

International Nuclear Information System (INIS)

Yakovleva, N.M.; Anicai, L.; Yakovlev, A.N.; Dima, L.; Khanina, E.Ya.; Buda, M.; Chupakhina, E.A.

2002-01-01

The paper presents the results of investigations of porous Al anodic films formed in HNO 3 electrolytes carried out by means of electrochemical techniques and X-ray diffraction as well as scanning electron microscopy (SEM). It was assumed that both electrochemical formation of a porous oxide and anodic dissolution of metal take place at Al/oxide interface at the same time. The analysis of short-range order (SRO) parameters for relatively high current density, 1x10 3 A/m 2 , and anodizing time, 10 min, leads to the conclusion that films mainly consist of amorphous alumina with γ'-Al 2 O 3 -like SRO and a small amount (∼10%) of amorphous aluminum oxyhydroxide. SEM investigation of the films revealed strong dependence of the surface relief on different applied forming conditions. This marked change in the surface relief is discussed taking into account the relatively complex behavior of Al during anodization in HNO 3 electrolytes, that involves both electrochemical growth and dissolution processes of anodic film associated with an electrochemical dissolution of aluminum substrate

Preparation of Cotton-Wool-Like Poly(lactic acid-Based Composites Consisting of Core-Shell-Type Fibers

Directory of Open Access Journals (Sweden)

Jian Wang

2015-11-01

Full Text Available In previous works, we reported the fabrication of cotton-wool-like composites consisting of siloxane-doped vaterite and poly(l-lactic acid (SiVPCs. Various irregularly shaped bone voids can be filled with the composite, which effectively supplies calcium and silicate ions, enhancing the bone formation by stimulating the cells. The composites, however, were brittle and showed an initial burst release of ions. In the present work, to improve the mechanical flexibility and ion release, the composite fiber was coated with a soft, thin layer consisting of poly(d,l-lactic-co-glycolic acid (PLGA. A coaxial electrospinning technique was used to prepare a cotton-wool-like material comprising “core-shell”-type fibers with a diameter of ~12 µm. The fibers, which consisted of SiVPC coated with a ~2-µm-thick PLGA layer, were mechanically flexible; even under a uniaxial compressive load of 1.5 kPa, the cotton-wool-like material did not exhibit fracture of the fibers and, after removing the load, showed a ~60% recovery. In Tris buffer solution, the initial burst release of calcium and silicate ions from the “core-shell”-type fibers was effectively controlled, and the ions were slowly released after one day. Thus, the mechanical flexibility and ion-release behavior of the composites were drastically improved by the thin PLGA coating.

Consistency and Stability of Italian Children's Spelling in Dictation versus Composition Assessments

Science.gov (United States)

Bigozzi, Lucia; Tarchi, Christian; Pinto, Giuliana

2017-01-01

The purpose of this study was to investigate consistency in spelling skills across 2 different tasks of written production (dictation vs. composition) and stability of performance across 4 different grades. We assessed 2nd, 3rd, 4th, and 5th graders' spelling performance through 4 tasks: 2 dictation tasks (passage and sentences) and 2 composition…

Characterization of silicon- and carbon-based composite anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Khomenko, Volodymyr G.; Barsukov, Viacheslav Z.

2007-01-01

In recent years development of active materials for negative electrodes has been of great interest. Special attention has been focused on the active materials possessing higher reversible capacity than that of conventional graphite. In the present work the electrochemical performance of some carbon/silicon-based materials has been analyzed. For this purpose various silicon-based composites were prepared using such carbon materials as graphite, hard carbon and graphitized carbon black. An analysis of charging-discharging processes at electrodes based on different carbon materials has shown that graphite modified with silicon is the most promising anode material. It has also been revealed that the irreversible capacity mainly depends on the content of Si. An optimum content of Si has been determined with taking into account that high irreversible capacity is not suitable for practical application in lithium-ion batteries. This content falls within the range of 8-10 wt%. The reversible capacity of graphite modified with 8 wt% carbon-coated Si was as high as 604 mAh g -1 . The irreversible capacity loss with this material was as low as 8.1%. The small irreversible capacity of the material allowed developing full lithium-ion rechargeable cells in the 2016 coin cell configuration. Lithium-ion batteries based on graphite modified with silicon show gravimetric and volumetric specific energy densities which are higher by approximately 20% than those for a lithium-ion battery based on natural graphite

Electrical and stability performance of anode-supported solid oxide fuel cells with strontium- and magnesium-doped lanthanum gallate thin electrolyte

Energy Technology Data Exchange (ETDEWEB)

Guo Weimin [College of Chemistry, South China University of Technology, Guangzhou 510640, Guangdong (China); Liu Jiang [College of Chemistry, South China University of Technology, Guangzhou 510640, Guangdong (China)], E-mail: jiangliu@scut.edu.cn; Zhang Yaohui [College of Chemistry, South China University of Technology, Guangzhou 510640, Guangdong (China)

2008-05-20

Anode-supported solid oxide fuel cells (SOFCs) comprising NiO-samarium-doped ceria (SDC) (Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9}) composite anode, thin tri-layer electrolyte, and La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3} (LSCF)-La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM) composite cathode were fabricated. The thin tri-layer consisting of an 11-{mu}m thick LSGM electrolyte layer and a 12-{mu}m thick La{sub 0.4}Ce{sub 0.6}O{sub 1.8} (LDC) layer on each side of the LSGM was prepared by centrifugal casting and co-firing technique. The performance of the cells operated with humidified H{sub 2} as fuel and ambient air as oxidant showed a maximum power density of 1.23 W cm{sup -2} at 800 deg. C. A stability test of about 100 h was carried out and some deterioration of output power was observed, while the open circuit voltage (OCV) kept unchanged. Impedance measurements showed that both the electrolyte ohmic resistance and the electrode polarization increased with time and the latter dominated the degradation.

Anodic oxidation of benzoquinone using diamond anode.

Science.gov (United States)

Panizza, Marco

2014-01-01

The anodic degradation of 1,4-benzoquinone (BQ), one of the most toxic xenobiotic, was investigated by electrochemical oxidation at boron-doped diamond anode. The electrolyses have been performed in a single-compartment flow cell in galvanostatic conditions. The influence of applied current (0.5-2 A), BQ concentration (1-2 g dm(-3)), temperature (20-45 °C) and flow rate (100-300 dm(3) h(-1)) has been studied. BQ decay kinetic, the evolution of its oxidation intermediates and the mineralization of the aqueous solutions were monitored during the electrolysis by high-performance liquid chromatograph (HPLC) and chemical oxygen demand (COD) measurements. The results obtained show that the use of diamond anode leads to total mineralization of BQ in any experimental conditions due to the production of oxidant hydroxyl radicals electrogenerated from water discharge. The decay kinetics of BQ removal follows a pseudo-first-order reaction, and the rate constant increases with rising current density. The COD removal rate was favoured by increasing of applied current, recirculating flow rate and it is almost unaffected by solution temperature.

Percolation effect on electrical, mechanical, and electrochemical properties of Sr{sub 0.8}La{sub 0.2}TiO{sub 3}–Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} composite anodes for solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Koo, Ji-Hoon [Division of Advanced Materials Engineering, Chonbuk National University, Jeonbuk, 561-756 (Korea, Republic of); Lee, Ki-Tae, E-mail: ktlee71@jbnu.ac.kr [Division of Advanced Materials Engineering, Chonbuk National University, Jeonbuk, 561-756 (Korea, Republic of); Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonbuk, 561-756 (Korea, Republic of)

2016-05-15

Both the electrical conductivity and mechanical strength of a Sr{sub 0.8}La{sub 0.2}TiO{sub 3}–Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (SLT-GDC) composite decreased non-linearly as the GDC content increased. In the GDC percolation region, the electrical conductivity and the mechanical strength decreased significantly. Because the carbon deposition rate increased with increasing GDC content, the redox stability decreased. The area specific resistance (ASR) of the SLT-GDC composite anode at 800 °C in H{sub 2} decreased up to 15 vol.% GDC (SLT-GDC15) and then increased at the SLT-GDC20 and the SLT-GDC33 compositions, due to the high electro–catalytic activity and low electrical conductivity of GDC. Consequently, the SLT-GDC15 composition within the mixed region below SLT and GDC percolation limit exhibited the best electrochemical performance due to the optimized electronic and ionic conduction network. - Highlights: • SLT-GDC composite anodes can be designed by percolation theory. • Incorporation of GDC improves catalytic activity. • Composite within SLT percolation threshold exhibits high mechanical strength. • Composite within the mixed percolation region exhibits the best catalytic activity. • Redox stability of the SLT-GDC composite is correlated with GDC volume.

Battery designs with high capacity anode materials and cathode materials

Energy Technology Data Exchange (ETDEWEB)

Masarapu, Charan; Anguchamy, Yogesh Kumar; Han, Yongbong; Deng, Haixia; Kumar, Sujeet; Lopez, Herman A.

2017-10-03

Improved high energy capacity designs for lithium ion batteries are described that take advantage of the properties of high specific capacity anode active compositions and high specific capacity cathode active compositions. In particular, specific electrode designs provide for achieving very high energy densities. Furthermore, the complex behavior of the active materials is used advantageously in a radical electrode balancing design that significantly reduced wasted electrode capacity in either electrode when cycling under realistic conditions of moderate to high discharge rates and/or over a reduced depth of discharge.

Combinatorial investigation of Pt-Ru-Sn alloys as an anode electrocatalysts for direct alcohol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Chu, Young Hwan [Department of New Energy.Resource Engineering, College of Science and Engineering, Sangji University, 124, Sangjidae-gil, Wonju-si, Gangwon-Do 220-702 (Korea); Shul, Yong Gun [Department of Chemical and Biomolecular Engineering, Yonsei University, 134, Shinchon-Dong, Seodaemun-Gu, Seoul 120-749 (Korea)

2010-10-15

Low-temperature direct alcohol fuel cells fed with different kinds of alcohol (methanol, ethanol and 2-propanol) have been investigated by employing ternary electrocatalysts (Pt-Ru-Sn) as anode catalysts. Combinatorial chemistry has been applied to screen the 66-PtRuSn-anode arrays at the same time to reduce cost, time, and effort when we select the optimum composition of electrocatalysts for DAFCs (Direct Alcohol Fuel Cells). PtRuSn (80:20:0) showed the lowest onset potential for methanol electro-oxidation, PtRuSn (50:0:50) for ethanol, and PtRuSn (20:70:10) for 2-propanol in CV results respectively, and single cell performance test indicated that Ru is more suitable for direct methanol fuel cell system, Sn for direct ethanol fuel cell system, and 2-propanol could be applied as fuel with low platinum composition anode electrocatalyst. The single cell performance results and electrochemical results (CV) were well matched with the combinatorial electrochemical results. As a result, we could verify the availability of combinatorial chemistry by comparing the results of each extreme electrocatalysts compositions as follows: PtRuSn (80:20:0) for methanol, PtRuSn (50:0:50) for ethanol and PtRuSn (20:70:10) for 2-propanol. (author)

Iron migration from the anode surface in alumina electrolysis

Energy Technology Data Exchange (ETDEWEB)

Zhuravleva, Elena N.; Drozdova, Tatiana N.; Ponomareva, Svetlana V. [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Kirik, Sergei D., E-mail: kiriksd@yandex.ru [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Institute of Chemistry and Chemical Technology SB RAS, Krasnoyarsk, 660036 (Russian Federation)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Corrosion destruction of two-component iron-based alloys in high-temperature aluminum electrolysis in the cryolite alumina melt has been studied. Black-Right-Pointing-Pointer It was found that at the first stage oxidative polarization of iron atoms on the anode surface into Fe{sup 2+} takes place. Black-Right-Pointing-Pointer Fe{sup 2+} interacts with cryolite melt producing FeF{sub 2}. Black-Right-Pointing-Pointer FeF{sub 2} gives oxides FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Black-Right-Pointing-Pointer The participation of oxygen in the corrosion has not been observed. - Abstract: Corrosion destruction of two-component iron-based alloys used as an anode in high-temperature alumina electrolysis in the melt of NaF/KF/AlF{sub 3} electrolyte has been considered. Ni, Si, Cu, Cr, Mn, Al, Ti in the amount of up to 10% have been tested as the dopants to an anode alloys. The composition of the corrosion products has been studied using X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It has been established that the anode corrosion is induced by a surface electrochemical polarization and iron atom oxidation. Iron ions come into an exchange interaction with the fluoride components of the melted electrolyte, producing FeF{sub 2}. The last interacts with oxyfluoride species transforming into the oxide forms: FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Due to the low solubility, the iron oxides are accumulated in the near-electrode sheath. The only small part of iron from anode migrates to cathode that makes an production of high purity aluminum of a real task. The alloy dopants are also subjected to corrosion in accordance with electromotive series resulting corrosion tunnels on the anode surface. The oxides are final compounds which collect in the same area. The corrosion products form an anode shell which is electronic conductor at electrolysis temperature. The

Nano-MnO2@TiO2 microspheres: A novel structure and excellent performance as anode of lithium-ion batteries

Science.gov (United States)

Cao, Zhiguang; Chen, Xiaoqiao; Xing, Lidang; Liao, Youhao; Xu, Mengqing; Li, Xiaoping; Liu, Xiang; Li, Weishan

2018-03-01

A structurally hierarchical MnO2/TiO2 composite (Nano-MnO2@TiO2) is fabricated by calcining MnCO3 microspheres and coating a thin layer of TiO2 through the heat decomposition of tetrabutyl titanate, and evaluated as anode of gravimetrically and volumetrically high energy density lithium ion battery. The characterizations from FESEM, TEM, HRTEM and XRD, indicate that the resulting Nano-MnO2@TiO2 takes a spherical morphology with a core of about 2 μm in diameter, consisting of compact MnO2 nanoparticles, and a shell of 60 nm thick, consisting of smaller TiO2 nanoparticles. The charge/discharge tests demonstrate that Nano-MnO2@TiO2 exhibits excellent performance as anode of lithium ion battery, delivering a capacity of 938 mAh g-1 at 300 mA g-1 after 200 cycles, compared to the 103 mAh g-1 of the uncoated sample. The microsphere consisting of compact nanoparticles provides Nano-MnO2@TiO2 with high specific gravity. The dimensionally and structurally stable TiO2 maintains the integrity of MnO2 microspheres and facilitates lithium insertion/extraction. This unique structure yields the excellent cyclic stability and rate capability of Nano-MnO2@TiO2.

Li-ion batteries from LiFePO{sub 4} cathode and anatase/graphene composite anode for stationary energy storage

Energy Technology Data Exchange (ETDEWEB)

Choi, Daiwon; Wang, Donghai; Viswanathan, Vish V.; Wang, Wei; Nie, Zimin; Zhang, Ji-Guang; Graff, Gordon L.; Liu, Jun; Yang, Zhenguo [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, WA 99352 (United States); Bae, In-Tae [Small Scale Systems Integration and Packaging Center, State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Duong, Tien [US Departments of Energy, 1000 Independence Ave., Washington, DC 20858 (United States)

2010-03-15

Li-ion batteries made from LiFePO{sub 4} cathode and anatase TiO{sub 2}/graphene composite anode were investigated for potential application in stationary energy storage. Fine-structured LiFePO{sub 4} was synthesized by a novel molten surfactant approach whereas anatase TiO{sub 2}/graphene nanocomposite was prepared via self-assembly method. The full cell that operated at 1.6 V demonstrated negligible fade even after more than 700 cycles at measured 1 C rate. While with relative lower energy density than traditional Li-ion chemistries interested for vehicle applications, the Li-ion batteries based on LiFePO{sub 4}/TiO{sub 2} combination potentially offers long life and low cost, along with safety, all which are critical to the stationary applications. (author)

Optical constants of anodic aluminum oxide films formed in oxalic acid solution

Energy Technology Data Exchange (ETDEWEB)

Wang Jian [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Wang Chengwei [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: cwwang@nwnu.edu.cn; Li Yan [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Liu Weimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2008-09-01

The anodic aluminum oxide (AAO) films with highly ordered nanopore arrays were prepared in oxalic acid solution under different anodizing voltage and time, its surface and cross section appearances were characterized by using field emission scanning electron microscopy, the transmission spectra with the interference fringes were measured at normal incidence over the wavelength range 200 to 2500 nm. Then the modified Swanepoel method was used for the determination of the optical constants and thickness of the free standing AAO films. The results indicate that the refractive index increases with the increase of anodizing voltage and the decrease of anodizing time, which is mainly due to the content of Al{sub 2}O{sub 3} with octahedron increases in the AAO films. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model, and the energy dependence of the absorption coefficient can be described using the direct transition model proposed by Tauc. Likewise, the optical energy gap E{sub g} is derived from Tauc's extrapolation, and E{sub g} increases from 4.178 to 4.256 eV with the anodizing voltage, but is weakly dependent on anodizing time. All the results are self-consistent in the paper.

Detailed characterization of anode-supported SOFCs by impedance spectroscopy

DEFF Research Database (Denmark)

Barfod, R.; Mogensen, Mogens Bjerg; Klemensø, Trine

2007-01-01

Anode-supported thin electrolyte cells are studied by electrochemical impedance spectroscopy (EIS). The aim is to describe how the losses of this type of cells are distributed at low current density (around open-circuit voltage) as a function of temperature. An equivalent circuit consisting...

Anodic behavior of Al-Zn-In sacrificial anodes at different concentration of zinc and indium

Energy Technology Data Exchange (ETDEWEB)

Keyvani, Ahmad [Shahrekord Univ. (Iran, Islamic Republic of). Dept. of Materials Engineering; Tehran Univ. (Iran, Islamic Republic of). School of Metallurgy and Materials; Saremi, Mohsen [Tehran Univ. (Iran, Islamic Republic of). School of Metallurgy and Materials; Saeri, Mohammad Reza [Shahrekord Univ. (Iran, Islamic Republic of). Dept. of Materials Engineering

2012-12-15

Al-Zn-In anodes show better performance due to the beneficial effects of Zn and In on prevention of aluminum passivity and producing a homogeneous structure for uniform corrosion of the anodes. However, there are different views about the optimum concentration of each element in the anode. In this study, the anodic behavior of Al-Zn-In alloy with different concentrations of zinc from 1 to 6wt.% and indium from 0.01 to 0.05wt.% are studied. The NACE efficiency test and polarization are used in 3wt.% NaCl solution for corrosion characterization. The results showed that zinc and indium change the anode potential to more active potentials and improve the microstructure uniformity of anodes. The latter leads to more uniform corrosion. Optimum concentrations of zinc (5wt.%) and indium (0.02wt.%) were found in this respect. (orig.)

Facile Synthesis of Carbon-Coated Spinel Li4Ti5O12/Rutile-TiO2 Composites as an Improved Anode Material in Full Lithium-Ion Batteries with LiFePO4@N-Doped Carbon Cathode.

Science.gov (United States)

Wang, Ping; Zhang, Geng; Cheng, Jian; You, Ya; Li, Yong-Ke; Ding, Cong; Gu, Jiang-Jiang; Zheng, Xin-Sheng; Zhang, Chao-Feng; Cao, Fei-Fei

2017-02-22

The spinel Li 4 Ti 5 O 12 /rutile-TiO 2 @carbon (LTO-RTO@C) composites were fabricated via a hydrothermal method combined with calcination treatment employing glucose as carbon source. The carbon coating layer and the in situ formed rutile-TiO 2 can effectively enhance the electric conductivity and provide quick Li + diffusion pathways for Li 4 Ti 5 O 12 . When used as an anode material for lithium-ion batteries, the rate capability and cycling stability of LTO-RTO@C composites were improved in comparison with those of pure Li 4 Ti 5 O 12 or Li 4 Ti 5 O 12 /rutile-TiO 2 . Moreover, the potential of approximately 1.8 V rechargeable full lithium-ion batteries has been achieved by utilizing an LTO-RTO@C anode and a LiFePO 4 @N-doped carbon cathode.

Advanced ceramic matrix composites for high energy x-ray generation

International Nuclear Information System (INIS)

Khan, Amir Azam; Labbe, Jean Claude

2011-01-01

High energy x-ray targets are the anodes used in high performance tubes, designed to work for long operating times and at high power. Such tubes are used in computed tomography (CT) scan machines. Usually the tubes used in CT scanners have to continuously work at high temperatures and for longer scan durations in order to get maximum information during a single scan. These anodes are composed of a refractory substrate which supports a refractory metallic coating. The present work is a review of the development of a ceramic metal composite based on aluminium nitride (AlN) and molybdenum for potential application as the substrate. This composite is surface engineered by coating with tungsten, the most popular material for high energy x-ray targets. To spray metallic coatings on the surface of ceramic matrix composites dc blown arc plasma is employed. The objective is to increase the performance and the life of an x-ray tube. Aluminium nitride-molybdenum ceramic matrix composites were produced by uniaxial hotpressing mixtures of AlN and Mo powders. These composites were characterized for their mechanical, thermal, electrical and micro-structural properties. An optimized composition was selected which contained 25 vol.% of metallic phase dispersed in the AlN matrix. These composites were produced in the actual size of an anode and coated with tungsten through dc blown arc plasma spraying. The results have shown that sintering of large size anodes is possible through uniaxial pressing, using a modified sintering cycle

Anodic composite deposition of RuO_2/reduced graphene oxide/carbon nanotube for advanced supercapacitors

International Nuclear Information System (INIS)

Hu, Chi-Chang; Wang, Chia-Wei; Chang, Kuo-Hsin; Chen, Ming-Guan

2015-01-01

Anodic composite deposition is demonstrated to be a unique method for fabricating a ternary ruthenium dioxide/reduced graphene oxide/carbon nanotube (RuO_2 · xH_2O/rGO/CNT, denoted as RGC) nanocomposite onto Ti as an advanced electrode material for supercapacitors. The rGO/CNT composite in RGCs acts as a conductive backbone to facilitate the electron transport between current collector and RuO_2 · xH_2O nanoparticles (NPs), revealed by the high total specific capacitance (C_S_,_T = 808 F g"−"1) of RGC without annealing. The contact resistance among RuO_2 · xH_2O NPs is improved by low-temperature annealing at 150 °C (RGC-150), which renders slight sintering and enhances the specific capacitance of RuO_2 · xH_2O to achieve 1200 F g"−"1. The desirable nanocomposite microstructure of RGC-150 builds up the smooth pathways of both protons and electrons to access the active oxy-ruthenium species. This nanocomposite exhibits an extremely high C_S_,_T of 973 F g"−"1 at 25 mV s"−"1 (much higher than 435 F g"−"1 of an annealed RuO_2 · xH_2O deposit) and good capacitance retention (60.5% with scan rate varying from 5 to 500 mV s"−"1), revealing an advanced electrode material for high-performance supercapacitors. (paper)

Confined SnO2 quantum-dot clusters in graphene sheets as high-performance anodes for lithium-ion batteries

Science.gov (United States)

Zhu, Chengling; Zhu, Shenmin; Zhang, Kai; Hui, Zeyu; Pan, Hui; Chen, Zhixin; Li, Yao; Zhang, Di; Wang, Da-Wei

2016-01-01

Construction of metal oxide nanoparticles as anodes is of special interest for next-generation lithium-ion batteries. The main challenge lies in their rapid capacity fading caused by the structural degradation and instability of solid-electrolyte interphase (SEI) layer during charge/discharge process. Herein, we address these problems by constructing a novel-structured SnO2-based anode. The novel structure consists of mesoporous clusters of SnO2 quantum dots (SnO2 QDs), which are wrapped with reduced graphene oxide (RGO) sheets. The mesopores inside the clusters provide enough room for the expansion and contraction of SnO2 QDs during charge/discharge process while the integral structure of the clusters can be maintained. The wrapping RGO sheets act as electrolyte barrier and conductive reinforcement. When used as an anode, the resultant composite (MQDC-SnO2/RGO) shows an extremely high reversible capacity of 924 mAh g−1 after 200 cycles at 100 mA g−1, superior capacity retention (96%), and outstanding rate performance (505 mAh g−1 after 1000 cycles at 1000 mA g−1). Importantly, the materials can be easily scaled up under mild conditions. Our findings pave a new way for the development of metal oxide towards enhanced lithium storage performance. PMID:27181691

Type I Clathrates as Novel Silicon Anodes: An Electrochemical and Structural Investigation

Science.gov (United States)

Li, Ying; Raghavan, Rahul; Wagner, Nicholas A.; Davidowski, Stephen K.; Baggetto, Loïc; Zhao, Ran; Cheng, Qian; Yarger, Jeffery L.; Veith, Gabriel M.; Ellis‐Terrell, Carol; Miller, Michael A.; Chan, Kwai S.

2015-01-01

Silicon clathrates contain cage‐like structures that can encapsulate various guest atoms or molecules. An electrochemical evaluation of type I silicon clathrates based on Ba8AlySi46−y as the anode material for lithium‐ion batteries is presented here. Postcycling characterization with nuclear magnetic resonance and X‐ray diffraction shows no discernible structural or volume changes even after electrochemical insertion of 44 Li (≈1 Li/Si) into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from large volume changes. The electrochemical reactions are proposed to occur as single phase reactions at approximately 0.2 and 0.4 V versus Li/Li+ during lithiation and delithiation, respectively, distinct from diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g−1 at a 5 mA g−1 rate were observed for silicon clathrate with composition Ba8Al8.54Si37.46, corresponding to ≈1.18 Li/Si. These results show that silicon clathrates could be promising durable anodes for lithium‐ion batteries. PMID:27980951

Consistent microscopic and phenomenological analysis of composite particle opticle potential

International Nuclear Information System (INIS)

Mukhopadhyay, Sheela; Srivastava, D.K.; Ganguly, N.K.

1976-01-01

A microscopic calculation of composits particle optical potential has been done using a realistic nucleon-helion interaction and folding it with the density distribution of the targets. The second order effects were simulated by introducing a scaling factor which was searched on to reproduce the experimental scattering results. Composite particle optical potential was also derived from the nucleon-nucleus optical potential. The second order term was explicitly treated as a parameter. Elastic scattering of 20 MeV 3 H on targets ranging from 40 Ca to 208 Pb to 208 Pb have also been analysed using phenomenological optical model. Agreement of these results with the above calculations verified the consistency of the microscopic theory. But the equivalent sharp radius calculated with n-helion interaction was observed to be smaller than phenomenological value. This was attributed to the absence of saturation effects in the density-independent interaction used. Saturation has been introduced by a density dependent term of the form (1-c zetasup(2/3)), where zeta is the compound density of the target helion system. (author)

Synthesis, Characterization, and Optimization of Novel Solid Oxide Fuel Cell Anodes

Science.gov (United States)

Miller, Elizabeth C.

This dissertation presents research on the development of novel materials and fabrication procedures for solid oxide fuel cell (SOFC) anodes. The work discussed here is divided into three main categories: all-oxide anodes, catalyst exsolution oxide anodes, and Ni-infiltrated anodes. The all-oxide and catalyst exsolution anodes presented here are further classi?ed as Ni-free anodes operating at the standard 700-800°C SOFC temperature while the Ni-infiltrated anodes operate at intermediate temperatures (≤650°C). Compared with the current state-of-the-art Ni-based cermets, all-oxide, Ni-free SOFC anodes offer fewer coking issues in carbon-containing fuels, reduced degradation due to fuel contaminants, and improved stability during redox cycling. However, electrochemical performance has proven inferior to Ni-based anodes. The perovskite oxide Fe-substituted strontium titanate (STF) has shown potential as an anode material both as a single phase electrode and when combined with Gd-doped ceria (GDC) in a composite electrode. In this work, STF is synthesized using a modified Pechini processes with the aim of reducing STF particle size and increasing the electrochemically active area in the anode. The Pechini method produced particles ? 750 nm in diameter, which is signi°Cantly smaller than the typically micron-sized solid state reaction powder. In the first iteration of anode fabrication with the Pechini powder, issues with over-sintering of the small STF particles limited gas di?usion in the anode. However, after modifying the anode firing temperature, the Pechini cells produced power density comparable to solid state reaction based cells from previous work by Cho et al. Catalyst exsolution anodes, in which metal cations exsolve out of the lattice under reducing conditions and form nanoparticles on the oxide surface, are another Ni-free option for standard operating temperature SOFCs. Little information is known about the onset of nanoparticle formation, which

Fe_3C@carbon nanocapsules/expanded graphite as anode materials for lithium ion batteries

International Nuclear Information System (INIS)

Huang, You-Guo; Lin, Xi-Le; Zhang, Xiao-Hui; Pan, Qi-Chang; Yan, Zhi-Xiong; Wang, Hong-Qiang; Chen, Jian-Jun; Li, Qing-Yu

2015-01-01

ABSTRACT: Fe_3C@carbonnanocapsules(*)/expanded graphite composite was successfully prepared by a new and facile method, including mix of starting materials and heat treatment of the precursor. It is featured by unique 3-D structure, where expanded graphite acts as scaffold to ensure a continuous entity, and Fe_3C particles coated by carbon nanocapsules are embedded intimately. The Fe_3C nanoparticles encased in carbon nanocapsules act as catalyst in the modification of SEI film during the cycles. The interesting 3-D architecture which aligns the conductivity paths in the planar direction with expanded graphite and in the axial direction with carbon nanocapsules minimizes the resistance and enhances the reversible capacity. The prepared composite exhibits a high reversible capacity and excellent rate performance as an anode material for lithium ion batteries. The composite maintains a reversible capacity of 1226.2 mAh/g after 75 cycles at 66 mA/g. When the current density increases to 200 mA/g, the reversible capacity maintains 451.5 mAh/g. The facile synthesis method and excellent electrochemical performances make the composite expected to be one of the most potential anode material for lithium ion batteries.

Computer Simulations of Composite Electrodes in Solid-Oxide Fuel-Cells

Energy Technology Data Exchange (ETDEWEB)

Sunde, Svein

1999-07-01

Fuel cells are devices for converting the combined chemical (free) energy of fuels and oxygen (air) directly to electrical energy without relying on the dynamic action of steam heated by reacting fuel-oxygen mixtures, like in steam turbines, or of the reacting gas mixtures themselves, like in gas turbines. The basic rationale for fuel cells is their high efficiencies as compared to indirect-conversion methods. Fuel cells are currently being considered for a number of applications, among them de-centralised power supply. Fuel cells come in five basic types and are usually classified according to the type of electrolyte used, which in turn to a significant degree limits the options for anode and cathode materials. The solid-oxide fuel-cell (SOFC) , with which this thesis is concerned, is thus named after its oxide electrolyte, typically the oxide-ion conducting material yttria-stabilised zirconia (YSZ). While the cathode of an SOFC is often uniform in chemical composition (or at least intended to be), various problems of delamination, cracking etc. associated with the use of metallic anode electrocatalysts led to the development of composite SOFC anodes. Porous anodes consisting of Ni and YSZ particles in roughly 50/50 wt-% mixtures are now almost standard with any SOFC-development programme. The designer of composite SOFC electrodes is faced with at least three, interrelated questions: (1) What will be the optimum microstructure and composition of the composite electrode? (2) If the structure changes during operation, as is often observed, what will be the consequences for the internal losses in the cell? (3) How do we interpret electrochemical and conductivity measurements with regard to structure and composition? It is the primary purpose of this thesis to provide a framework for modelling the electrochemical and transport properties of composite electrodes for SOFC, and to arrive at some new insights that cannot be offered by experiment alone. Emphasis is put on

Synthesis and electrochemical performances of amorphous carbon-coated Sn Sb particles as anode material for lithium-ion batteries

Science.gov (United States)

Wang, Zhong; Tian, Wenhuai; Liu, Xiaohe; Yang, Rong; Li, Xingguo

2007-12-01

The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn-Sb alloy and carbon alone. This amorphous carbon-coated Sn-Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use.

Nano structural anodes for radiation detectors

Science.gov (United States)

Cordaro, Joseph V.; Serkiz, Steven M.; McWhorter, Christopher S.; Sexton, Lindsay T.; Retterer, Scott T.

2015-07-07

Anodes for proportional radiation counters and a process of making the anodes is provided. The nano-sized anodes when present within an anode array provide: significantly higher detection efficiencies due to the inherently higher electric field, are amenable to miniaturization, have low power requirements, and exhibit a small electromagnetic field signal. The nano-sized anodes with the incorporation of neutron absorbing elements (e.g., .sup.10B) allow the use of neutron detectors that do not use .sup.3He.

Rapid fabrication of self-ordered porous alumina with 10-/sub-10-nm-scale nanostructures by selenic acid anodizing

Science.gov (United States)

Nishinaga, Osamu; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2013-01-01

Anodic porous alumina has been widely investigated and used as a nanostructure template in various nanoapplications. The porous structure consists of numerous hexagonal cells perpendicular to the aluminum substrate and each cell has several tens or hundreds of nanoscale pores at its center. Because the nanomorphology of anodic porous alumina is limited by the electrolyte during anodizing, the discovery of additional electrolytes would expand the applicability of porous alumina. In this study, we report a new self-ordered nanoporous alumina formed by selenic acid (H2SeO4) anodizing. By optimizing the anodizing conditions, anodic alumina possessing 10-nm-scale pores was rapidly assembled (within 1 h) during selenic acid anodizing without any special electrochemical equipment. Novel sub-10-nm-scale spacing can also be achieved by selenic acid anodizing and metal sputter deposition. Our new nanoporous alumina can be used as a nanotemplate for various nanostructures in 10-/sub-10-nm-scale manufacturing. PMID:24067318

Interelectrode plasma evolution in a hot refractory anode vacuum arc: Theory and comparison with experiment

International Nuclear Information System (INIS)

Beilis, I.I.; Goldsmith, S.; Boxman, R.L.

2002-01-01

In this paper a theoretical study of a hot refractory anode vacuum arc, which was previously investigated experimentally [Phys. Plasmas 7, 3068 (2000)], is presented. The arc was sustained between a thermally isolated refractory anode and a water-cooled copper cathode. The arc started as a multicathode-spot (MCS) vacuum arc and then switched to the hot refractory anode vacuum arc (HRAVA) mode. In the MCS mode, the cathodic plasma jet deposits a film of the cathode material on the anode. Simultaneously, the temperature of the thermally isolated anode begins to rise, reaching eventually a sufficiently high temperature to re-evaporate the deposited material, which is subsequently ionized in the interelectrode gap. The transition to the HRAVA mode is completed when the density of the interelectrode plasma consists mostly of ionized re-evaporated atoms--the anode plasma. The evolution of the HRAVA mode is characterized by the propagation of a luminous plasma plume from the anode to the cathode. The time dependent model of the various physical processes taking place during the transition to the HRAVA mode is represented by a system of equations describing atom re-evaporation, atom ionization through the interaction of the cathode jet and the interelectrode plasma with the anode vapor, plasma plume propagation, plasma radial expansion, plasma energy, and heavy particle density balance. The time dependence of the anode heat flux and the effective anode voltage were obtained by solving these equations. In addition, the time dependent plasma electron temperature, plasma density, anode potential drop, arc voltage, and anode temperature distribution were calculated and compared with previous measurements. It was shown that the observed decrease of the effective anode voltage with time during the mode transition is due to decrease of the heat flux incident on the anode surface from the cathode spot jets

°Enhancing High Temperature Anode Performance with 2° Anchoring Phases

Energy Technology Data Exchange (ETDEWEB)

Walker, Robert A. [Montana State Univ., Bozeman, MT (United States); Sofie, Stephen W. [Montana State Univ., Bozeman, MT (United States); Amendola, Roberta [Montana State Univ., Bozeman, MT (United States)

2015-10-01

Project accomplishments included developing and optimizing strength testing of aluminum titanate (ALT)-doped Ni-YSZ materials and identified the dopant levels that optimized mechanical strength and enhanced electrochemical performance. We also optimized our ability to fabricate electrolyte supported button cells with anodes consisting of powders provided by Fuel Cell Energy. In several instances, those anodes were infiltrated with ALT and tested with hydrogen for 30 hours at 800°C at an applied potential of 0.4 V. Our research activities were focused in three areas: 1) mechanical strength testing on as prepared and reducced nickel-YSZ structures that were either free of a dopant or prepared by mechanically mixing in ALT at various weight percents (up to 10 wt%); 2) 24-hour electrochemical testing of electroylte supported cells having anodes made from Ni/YSZ and Ni/YSZ/ALT anodes with specific attention focused on modeling degradation rates; and 3) operando EIS and optical testing of both in-house fabricated devices as well as membrane electrode assemblies that were acquired from commercial vendors.

Electrostatic spray deposition of porous SnO₂/graphene anode films and their enhanced lithium-storage properties.

Science.gov (United States)

Jiang, Yinzhu; Yuan, Tianzhi; Sun, Wenping; Yan, Mi

2012-11-01

Porous SnO₂/graphene composite thin films are prepared as anodes for lithium ion batteries by the electrostatic spray deposition technique. Reticular-structured SnO₂ is formed on both the nickel foam substrate and the surface of graphene sheets according to the scanning electron microscopy (SEM) results. Such an assembly mode of graphene and SnO₂ is highly beneficial to the electrochemical performance improvement by increasing the electrical conductivity and releasing the volume change of the anode. The novel engineered anode possesses 2134.3 mA h g⁻¹ of initial discharge capacity and good capacity retention of 551.0 mA h g⁻¹ up to the 100th cycle at a current density of 200 mA g⁻¹. This anode also exhibits excellent rate capability, with a reversible capacity of 507.7 mA h g⁻¹ after 100 cycles at a current density of 800 mA g⁻¹. The results demonstrate that such a film-type hybrid anode shows great potential for application in high-energy lithium-ion batteries.

Single-walled carbon nanotubes as stabilizing agents in red phosphorus Li-ion battery anodes

KAUST Repository

Smajic, Jasmin; Alazmi, Amira; Patole, Shashikant P.; Da Costa, Pedro M. F. J.

2017-01-01

improvement in the electrochemical stability of battery anodes. In contrast to the average 40% loss of capacity after 50 cycles for other phosphorus–carbon composites in the literature, our material shows losses of just 22% under analogous cycling conditions.

Chemical compositions, methods of making the chemical compositions, and structures made from the chemical compositions

Science.gov (United States)

Yang, Lei; Cheng, Zhe; Liu, Ze; Liu, Meilin

2015-01-13

Embodiments of the present disclosure include chemical compositions, structures, anodes, cathodes, electrolytes for solid oxide fuel cells, solid oxide fuel cells, fuel cells, fuel cell membranes, separation membranes, catalytic membranes, sensors, coatings for electrolytes, electrodes, membranes, and catalysts, and the like, are disclosed.

Structural analysis of highly-durable Si-O-C composite anode prepared by electrodeposition for lithium secondary batteries

International Nuclear Information System (INIS)

Nara, Hiroki; Yokoshima, Tokihiko; Otaki, Mitsutoshi; Momma, Toshiyuki; Osaka, Tetsuya

2013-01-01

The structure of the highly durable silicon-based anode prepared by electrodeposition was investigated for volume change and chemical structure. With repeated charge–discharge cycles, the volume change resulting from the anode film thickness decreased, and, after 100 cycles, essentially no difference was observed between the charged and discharged states. The buffering effect of the volume change was considered to be achieved by the formation of Li 2 O, Li 2 CO 3 , and lithium silicates such as Li 4 SiO 4 , whose existence were supported by STEM, EELS, and XPS analyses. From the structural analyses, the main reactions related to the capacity of the silicon-based anode were considered to be the formation of Li x Si and Li 2 Si 2 O 5 . Li x Si and Li 2 Si 2 O 5 can be delithiated into Si and SiO 2 , respectively

A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions.

Science.gov (United States)

Li, Y J; Wang, Y G; An, B; Xu, H; Liu, Y; Zhang, L C; Ma, H Y; Wang, W M

2016-01-01

A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials.

Variation of nanopore diameter along porous anodic alumina channels by multi-step anodization.

Science.gov (United States)

Lee, Kwang Hong; Lim, Xin Yuan; Wai, Kah Wing; Romanato, Filippo; Wong, Chee Cheong

2011-02-01

In order to form tapered nanocapillaries, we investigated a method to vary the nanopore diameter along the porous anodic alumina (PAA) channels using multi-step anodization. By anodizing the aluminum in either single acid (H3PO4) or multi-acid (H2SO4, oxalic acid and H3PO4) with increasing or decreasing voltage, the diameter of the nanopore along the PAA channel can be varied systematically corresponding to the applied voltages. The pore size along the channel can be enlarged or shrunken in the range of 20 nm to 200 nm. Structural engineering of the template along the film growth direction can be achieved by deliberately designing a suitable voltage and electrolyte together with anodization time.

Reactions on carbon anodes in aluminium electrolysis

Energy Technology Data Exchange (ETDEWEB)

Eidet, Trygve

1997-12-31

The consumption of carbon anodes and energy in aluminium electrolysis is higher than what is required theoretically. This thesis studies the most important of the reactions that consume anode materials. These reactions are the electrochemical anode reaction and the airburn and carboxy reactions. The first part of the thesis deals with the kinetics and mechanism of the electrochemical anode reaction using electrochemical impedance spectroscopy. The second part deals with air and carboxy reactivity of carbon anodes and studies the effects of inorganic impurities on the reactivity of carbon anodes in the aluminium industry. Special attention is given to sulphur since its effect on the carbon gasification is not well understood. Sulphur is always present in anodes, and it is expected that the sulphur content of available anode cokes will increase in the future. It has also been suggested that sulphur poisons catalyzing impurities in the anodes. Other impurities that were investigated are iron, nickel and vanadium, which are common impurities in anodes which have been reported to catalyze carbon gasification. 88 refs., 92 figs., 24 tabs.

Effects of Alclad Layer and Anodizing Time on Sulfuric Acid Anodizing and Film Properties of 2E12 Aluminum Alloy

Directory of Open Access Journals (Sweden)

CHEN Gao-hong

2017-07-01

Full Text Available Alclad and unclad 2E12 aerospace aluminum alloy were treated by sulfuric acid anodic oxidation. The effects of alclad layer and anodizing time on the anodization behaviour and corrosion resistance of anodic oxide layer on 2E12 aluminum alloy were studied. Surface and cross-section morphology of anodic oxide films were observed by scanning electron microscopy. The electrochemical properties of anodic oxide films were analyzed by potentiodynamic polarization curve and electrochemical impedance spectroscopy. The results show that the protective anodic oxide layers are formed on alclad and unclad 2E12 aluminum alloy. The film thickness increases with anodizing time extending. The copper rich second phase particles lead to more cavity defects and even micro cracks on anodic oxide films of unclad 2E12 aluminum alloy. The anodic oxide films on alclad 2E12 aluminum alloy are thicker and have fewer cavity defects, resulting in better corrosion resistance. The films obtained after 30min and 45min anodic oxidation treatment exhibit lower corrosion current and higher impedance of the porous layer than other anodizing time.

Growth Mechanism of γ-MnS Nanorod-Arrays by Hydrothermal Method on Anodic Aluminum Oxide Template

International Nuclear Information System (INIS)

Huang, Jianming; Liu, Weifeng; Lv, Yong; Yao, Lianzeng

2010-01-01

Hydrothermal method is a general, low-cost and convenience method which was utilized for synthesis of nanomaterials. Our research group has reported that oriented MnS nanorods on anodic aluminum oxide template were synthesized under a hydrothermal condition and demonstrated the effect of precursor content on the morphology evolution of as-samples. In order to research the growth mechanism of the arrays, herein we synthesized MnS nanorod arrays by combination of anodic aluminum oxide template and hydrothermal method on different substrates. Through-hole anodic aluminum oxide templates were prepared using Al foil (99.999%) via a two-step anodization process as described in literature. To investigate the effect of different substrates on the morphology of the-products, different substrates including anodic aluminum oxide template (sample A), one-step anodization Al foil (sample B, which was prepared by first anodizing Al foil for 10h and then removing the alumina layer with the mixed acid (0.6 M H 3 PO 4 and 0.15 M H 2 CrO 4 ), where the foil still kept the close-packed concave nano-pits consistently with the nanopole of anodic aluminum oxide template), Al foil (sample C, dipped in HNO 3 solution and covered by a compact alumina layer), Si wafer (sample D) respectively were put into Teflon-lined stainless steel autoclaves of 20 mL capacity filled with 16 mL mixed solution consisting of 2 mol/L MnCl 4 and 2 mol/L thiourea. We kept the reaction at 150 .deg. C for 20 h. When reactions completed the products were washed three times with distilled water and absolute ethanol, respectively. Then the products were dried in an oven at 60 .deg. C

Growth Mechanism of γ-MnS Nanorod-Arrays by Hydrothermal Method on Anodic Aluminum Oxide Template

Energy Technology Data Exchange (ETDEWEB)

Huang, Jianming; Liu, Weifeng; Lv, Yong; Yao, Lianzeng [Chinese Academy of Science, Hefei, Anhui (China)

2010-09-15

Hydrothermal method is a general, low-cost and convenience method which was utilized for synthesis of nanomaterials. Our research group has reported that oriented MnS nanorods on anodic aluminum oxide template were synthesized under a hydrothermal condition and demonstrated the effect of precursor content on the morphology evolution of as-samples. In order to research the growth mechanism of the arrays, herein we synthesized MnS nanorod arrays by combination of anodic aluminum oxide template and hydrothermal method on different substrates. Through-hole anodic aluminum oxide templates were prepared using Al foil (99.999%) via a two-step anodization process as described in literature. To investigate the effect of different substrates on the morphology of the-products, different substrates including anodic aluminum oxide template (sample A), one-step anodization Al foil (sample B, which was prepared by first anodizing Al foil for 10h and then removing the alumina layer with the mixed acid (0.6 M H{sub 3}PO{sub 4} and 0.15 M H{sub 2}CrO{sub 4}), where the foil still kept the close-packed concave nano-pits consistently with the nanopole of anodic aluminum oxide template), Al foil (sample C, dipped in HNO{sub 3} solution and covered by a compact alumina layer), Si wafer (sample D) respectively were put into Teflon-lined stainless steel autoclaves of 20 mL capacity filled with 16 mL mixed solution consisting of 2 mol/L MnCl{sub 4} and 2 mol/L thiourea. We kept the reaction at 150 .deg. C for 20 h. When reactions completed the products were washed three times with distilled water and absolute ethanol, respectively. Then the products were dried in an oven at 60 .deg. C.

Processing of composites based on NiO, samarium-doped ceria and carbonates (NiO-SDCC as anode support for solid oxide fuel cells

Directory of Open Access Journals (Sweden)

Lily Siong Mahmud

2017-09-01

Full Text Available NiO-SDCC composites consisting of NiO mixed with Sm-doped ceria (SDC and carbonates (Li2CO3 and Na2CO3 were sintered at different temperatures and reduced at 550 °C. The influence of reduction on structure of the NiO-SDCC anode support for solid oxide fuel cells (SOFCs was investigated. Raman spectra of the NiO-SDCC samples sintered at 500, 600 and 700 °C showed that after reducing at 550 °C NiO was reduced to Ni. In addition, SDC and carbonates (Li2CO3 and Na2CO3 did not undergo chemical transformation after reduction and were still detected in the samples. However, no Raman modes of carbonates were identified in the NiO-SDCC pellet sintered at 1000 °C and reduced at 550 °C. It is suspected that carbonates were decomposed at high sintering temperature and eliminated due to the reaction between the CO32– and hydrogen ions during reduction in humidified gases at 550 °C. The carbonate decomposition increased porosity in the Ni-SDCC pellets and consequently caused formation of brittle and fragile structure unappropriated for SOFC application. Because of that composite NiO-SDC samples without carbonates were also analysed to determine the factors affecting the crack formation. In addition, it was shown that the different reduction temperatures also influenced the microstructure and porosity of the pellets. Thus, it was observed that Ni-SDC pellet reduced at 800 °C has higher electrical conductivity of well-connected microstructures and sufficient porosity than the pellet reduced at 550 °C.

The Incorporation of Lithium Alloying Metals into Carbon Matrices for Lithium Ion Battery Anodes

Science.gov (United States)

Hays, Kevin A.

arsenic particles that were synthesized on melt away carbon nanotubes by akalide reduction. The performance of these anodes proved sensitive to electrolyte composition, which was significantly improved by using fluorinated ethylene carbonate. Additionally, further gains in capacity retention can be made by limiting the loading voltage to 0.75 V vs lithium metal. The arsenic and melt away carbon nanotube composite was found to have excellent cycle life and capacity at high mass loading (80% arsenic) when the nanoparticles were directly synthesized on the melt away carbon nanotubes. Gallium arsenide is well known for its semiconducting properties, but its performance as in Li-ion battery anodes is first reported here. Gallium is a metal with a low melting point that has been touted as a possible self-healing material for lithium ion anodes. Alone, gallium proves to be unstable as a lithium ion battery anode, but when synthesized as gallium arsenide nanoparticles and mixed with melt away carbon nanotubes it can charge and discharge in a battery 100 times with approximately twice the capacity of graphite anodes. This first study of gallium arsenide shows dramatic cycle life improvements by using nanoscale rather that micron size gallium arsenide.

Enhanced performance of microbial fuel cells by using MnO_2/Halloysite nanotubes to modify carbon cloth anodes

International Nuclear Information System (INIS)

Chen, Yingwen; Chen, Liuliu; Li, Peiwen; Xu, Yuan; Fan, Mengjie; Zhu, Shemin; Shen, Shubao

2016-01-01

The modification of anode materials is important to enhance the power generation of MFCs (microbial fuel cells). A novel and cost-effective modified anode that is fabricated by dispersing manganese dioxide (MnO_2) and HNTs (Halloysite nanotubes) on carbon cloth to improve the MFCs' power production was reported. The results show that the MnO_2/HNT anodes acquire more bacteria and provide greater kinetic activity and power density compared to the unmodified anode. Among all modified anodes, 75 wt% MnO_2/HNT exhibits the highest electrochemical performance. The maximum power density is 767.3 mWm"−"2, which 21.6 higher than the unmodified anode (631 mW/m"2). Besides, CE (Coulombic efficiency) was improved 20.7, indicating that more chemical energy transformed to electricity. XRD (X-Ray powder diffraction) and FTIR (Fourier transform infrared spectroscopy) are used to characterize the structure and functional groups of the anode. CV (cyclic voltammetry) scans and SEM (scanning electron microscope) images demonstrate that the measured power density is associated with the attachment of bacteria, the microorganism morphology differed between the modified and the original anode. These findings demonstrate that MnO_2/HNT nanocomposites can alter the characteristics of carbon cloth anodes to effectively modify the anode for practical MFC applications. - Highlights: • Different contents of MnO_2/HNT composites were prepared and used to modify anodes in MFCs. • The performance of MFCs was improved by the anode modification. • 75% wt MnO_2/HNT modified anode showed the better capacity on power density. • Water contact angle, CV, SEM were determined to figure out the effect of modification on MFCs. • MnO_2/HNT modified anode in MFCs was first studied to push MFCs technology forward.

Sodium fluoride-assisted modulation of anodized TiO₂ nanotube for dye-sensitized solar cells application.

Science.gov (United States)

Yun, Jung-Ho; Ng, Yun Hau; Ye, Changhui; Mozer, Attila J; Wallace, Gordon G; Amal, Rose

2011-05-01

This work reports the use of sodium fluoride (in ethylene glycol electrolyte) as the replacement of hydrofluoric acid and ammonium fluoride to fabricate long and perpendicularly well-aligned TiO₂ nanotube (TNT) (up to 21 μm) using anodization. Anodizing duration, applied voltage and electrolyte composition influenced the geometry and surface morphologies of TNT. The growth mechanism of TNT is interpreted by analyzing the current transient profile and the total charge density generated during anodization. The system with low water content (2 wt %) yielded a membrane-like mesoporous TiO₂ film, whereas high anodizing voltage (70 V) resulted in the unstable film of TNT arrays. An optimized condition using 5 wt % water content and 60 V of anodizing voltage gave a stable array of nanotube with controllable length and pore diameter. Upon photoexcitation, TNTs synthesized under this condition exhibited a slower charge recombination rate as nanotube length increased. When made into cis-diisothiocyanato-bis(2,2̀-bipyridyl-4,4̀-dicarboxylato) ruthenium(II) bis (tetrabutyl-ammonium)(N719) dye-sensitized solar cells, good device efficiency at 3.33 % based on the optimized TNT arrays was achieved with longer electron time compared with most mesoporous TiO₂ films.

Anodic behavior of stainless-steel substrate in organic electrolyte solutions containing different lithium salts

International Nuclear Information System (INIS)

Furukawa, Kazuki; Yoshimoto, Nobuko; Egashira, Minato; Morita, Masayuki

2014-01-01

Highlights: • We investigated anodic behavior of stainless-steel in organic electrolytes for advanced capacitor. • Anion of the electrolyte affected the anodic stability of the alloy. • Anodic passivation occurs in LiPF 6 solution but pitting or active dissolution proceeds in other electrolyte solutions. • Fluoride source in the solution contributes to forming a stable surface layer on the stainless steel. - Abstract: The anodic behavior of austenitic stainless-steel, SUS304, as a current collector of positive electrode in lithium-ion battery/capacitor has been investigated in organic electrolyte solutions based on a mixed alkyl carbonate solvent with different lithium salts. Stable passivation characteristics were observed for the stainless-steel in the LiPF 6 solution, but pitting corrosion or active dissolution proceeded in the solutions containing other anions, BF 4 - , (CF 3 SO 2 ) 2 N - (TFSA - ) and ClO 4 - . The mass ratios of the dissolved metal species in the solutions of LiTFSA and LiClO 4 were equivalent to that of the alloy composition, which suggests that no preferential dissolution occurs during the anodic polarization in these electrolyte solutions. An HF component formed by decomposition of PF 6 - with the contaminate water will act as an F - source for the formation of a surface fluoride layer, that will contribute to the anodic stability of SUS304 in the LiPF 6 solution. The anodic corrosion in the LiTFSA solution was suppressed in part by mixing the PF 6 salt or adding HF in the electrolyte

Microscopic observation of pattern attack by aggressive ions on finished surface of aluminium alloy sacrificial anode

International Nuclear Information System (INIS)

Zaifol Samsu; Muhammad Daud; Siti Radiah Mohd Kamarudin; Nur Ubaidah Saidin; Azali Muhammad; Mohd Shaari Ripin; Rusni Rejab; Mohd Shariff Sattar

2010-01-01

This paper presents the results of a microscopic observation on submerged finished surface of aluminium alloy sacrificial anode. Experimental tests were carried out on polished surface aluminium anode exposed to seawater containing aggressive ions in order to observe of pattern corrosion attack on corroding surface of anode. Results have shown, at least under the present testing condition, that surface of sacrificial anode were attack by an aggressive ion such as chloride along grain boundaries. In addition, results of microanalysis showed that the corrosion products on surface of aluminium alloy have Al, Zn and O element for all sample and within the pit was consists of Al, Zn, O and Cl element. (author)

Method for providing uranium articles with a corrosion resistant anodized coating

International Nuclear Information System (INIS)

Waldrop, F.B.; Washington, C.A.

1982-01-01

Uranium articles are provided with anodized oxide coatings in an aqueous solution of an electrolyte selected from the group consisting of potassium phosphate, potassium hydroxide, ammonium hydroxide, and a mixture of potassium tetraborate and boric acid. The uranium articles are anodized at a temperature greater than about 75 degrees C. With a current flow of less than about 0.036 A/cm2 of surface area while the Ph of the solution is maintained in a range of about 2 to 11.5. The Ph values of the aqueous solution and the low current density utilized during the electrolysis prevent excessive dissolution of the uranium and porosity in the film or watering. The relatively high temperature of the electrolyte bath inhibits hydration and the attendant deleterious pitting so as to enhance corrosion resistance of the anodized coating

High performance electrodes for reduced temperature solid oxide fuel cells with doped lanthanum gallate electrolyte. I. Ni-SDC cermet anode

Science.gov (United States)

Ohara, S.; Maric, R.; Zhang, X.; Mukai, K.; Fukui, T.; Yoshida, H.; Inagaki, T.; Miura, K.

A Ni-samaria-doped ceria (SDC) cermet was selected as the anode material for reduced temperature (800°C) solid oxide fuel cells. The NiO-SDC composite powder, synthesized by spray pyrolysis, was employed as the starting anode powder in this study. The influence of Ni content in Ni-SDC cermets on the electrode performance was investigated in order to create the most suitable microstructures. It was found that anodic polarization was strongly influenced by the Ni content in Ni-SDC cermets. The best results were obtained for anode cermets with Ni content of around 50 vol.%; anodic polarization was about 30 mV at a current density of 300 mA/cm 2. This high performance seems to be attributable to the microstructure, in which Ni grains form a skeleton with well-connected SDC grains finely distributed over the Ni grains surfaces; such microstructure was also conducive to high stability of the anode.

Tin phosphide-based anodes for sodium-ion batteries: synthesis via solvothermal transformation of Sn metal and phase-dependent Na storage performance

Science.gov (United States)

Shin, Hyun-Seop; Jung, Kyu-Nam; Jo, Yong Nam; Park, Min-Sik; Kim, Hansung; Lee, Jong-Won

2016-01-01

There is a great deal of current interest in the development of rechargeable sodium (Na)-ion batteries (SIBs) for low-cost, large-scale stationary energy storage systems. For the commercial success of this technology, significant progress should be made in developing robust anode (negative electrode) materials with high capacity and long cycle life. Sn-P compounds are considered promising anode materials that have considerable potential to meet the required performance of SIBs, and they have been typically prepared by high-energy mechanical milling. Here, we report Sn-P-based anodes synthesised through solvothermal transformation of Sn metal and their electrochemical Na storage properties. The temperature and time period used for solvothermal treatment play a crucial role in determining the phase, microstructure, and composition of the Sn-P compound and thus its electrochemical performance. The Sn-P compound prepared under an optimised solvothermal condition shows excellent electrochemical performance as an SIB anode, as evidenced by a high reversible capacity of ~560 mAh g−1 at a current density of 100 mA g−1 and cycling stability for 100 cycles. The solvothermal route provides an effective approach to synthesising Sn-P anodes with controlled phases and compositions, thus tailoring their Na storage behaviour. PMID:27189834

Copper Antimonide Nanowire Array Lithium Ion Anodes Stabilized by Electrolyte Additives.

Science.gov (United States)

Jackson, Everett D; Prieto, Amy L

2016-11-09

Nanowires of electrochemically active electrode materials for lithium ion batteries represent a unique system that allows for intensive investigations of surface phenomena. In particular, highly ordered nanowire arrays produced by electrodeposition into anodic aluminum oxide templates can lead to new insights into a material's electrochemical performance by providing a high-surface-area electrode with negligible volume expansion induced pulverization. Here we show that for the Li-Cu x Sb ternary system, stabilizing the surface chemistry is the most critical factor for promoting long electrode life. The resulting solid electrolyte interphase is analyzed using a mix of electron microscopy, X-ray photoelectron spectroscopy, and lithium ion battery half-cell testing to provide a better understanding of the importance of electrolyte composition on this multicomponent alloy anode material.

Electrochemical performance of 2D polyaniline anchored CuS/Graphene nano-active composite as anode material for lithium-ion battery.

Science.gov (United States)

Iqbal, Shahid; Bahadur, Ali; Saeed, Aamer; Zhou, Kebin; Shoaib, Muhammad; Waqas, Muhammad

2017-09-15

Lithium-ion battery (LIB) is a revolutionary step in the electric energy storage technology for making green environment. In the present communication, a LIB anode material was constructed by using graphene/polyaniline/CuS nanocomposite (GR/PANI/CuS NC) as a high-performance electrode. Initially, pure covellite CuS nanoplates (NPs) of the hexagonal structure were synthesized by hydrothermal route and then GR/PANI/CuS NC was fabricated by in-situ polymerization of aniline in the presence of CuS NPs and graphene nanosheets (GR NSs) as host matrix. GR/PANI/CuS NC-based LIB has shown the superior reversible current capacity of 1255mAhg -1 , a high cycling stability with more than 99% coulombic efficiency over 250 cycles even at a high current density of 5Ag -1 , low volume expansion, and excellent power capabilities. Galvanostatic charge/discharge tests and cyclic voltammetry analysis were used to investigate electrochemical properties. The electrochemical test proves that GR/PANI/CuS NC is promising anode material for LIB. The crystal phases and purity of the GR/PANI/CuS NC were confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) were employed to examine the morphology, size, chemical composition, and phase structure of the synthesized GR/PANI/CuS NC. Copyright © 2017. Published by Elsevier Inc.

Anodic behavior of alloy 22 in bicarbonate containing media: Effect of alloying

International Nuclear Information System (INIS)

Zadorozne, N S; Giordano, C M; Rebak, R B; Ares, A E; Carranza, R M

2012-01-01

Alloy 22 is one of the candidates for the manufacture of high level nuclear waste containers. These containers provide services in natural environments characterized by multi-ionic solutions.It is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (specifically crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate and chloride ions is necessary to produce cracking, . It has also been determined that the susceptibility to SCC could be related to the occurrence of an anodic peak in the polarization curves in these media at potentials below transpassivity. The aim of this work is to study the effect of alloying elements on the anodic behavior of Alloy 22 in media containing bicarbonate and chloride ions at different concentrations and temperatures. Polarization curves were made on alloy 22 (Ni-22% Cr-13% Mo), Ni-Mo (Ni-28, 5% Mo) and Ni-Cr (Ni-20% Cr) in the following solutions: 1 mol/L NaCl at 90 o C, and 1.148 mol/L NaHCO 3 ; 1.148 mol/L NaHCO 3 + 1 mol/L NaCl; 1.148 mol/L NaHCO 3 + 0.1 mol/L NaCl, at 90 o C, 75 o C, 60 o C and 25 o C. It was found that alloy 22 has a anodic current density peak at potentials below transpassivity, only in the presence of bicarbonate ions. Curves performed in 1 mol/L NaCl did not show any anodic peak, in any of the tested alloys. The curves made on alloys Ni-Mo and Ni-Cr in the presence of bicarbonate ions, allowed to determine that Cr, is responsible for the appearance of the anodic peak in alloy 22. The curves of alloy Ni-Mo showed no anodic peak in the studied conditions. The potential at which the anodic peak appears in alloy 22 and Ni-Cr alloy, increases with decreasing temperature. The anodic peak was also affected by solution composition. When chloride ion is added to bicarbonate solutions, the anodic peak is shifted to higher potential and current densities, depending on the concentration of added chloride ions (author)

Based on Cu as framework constructed nanoporous CuO/Cu composites by a dealloy method for sodium-ion battery anode

Science.gov (United States)

Zheng, Tian; Li, Guangda; Li, Deming; Meng, Xiangeng

2018-05-01

Nanoporous CuO/Cu composites with a continuous channel structure were fabricated through a corroding Cu-Al alloy process. The width of the continuous channels was about 20 50 nm. Nanoporous structure could effectively sustain the volume expansion during the Na+ insertion/extraction process and shorten the Na+ diffusion length as well, which thus helps improve the Na+ storage performance. Moreover, the nanoporous structure can improve the contact area between the electrolyte and the electrode, leading to an increment in the number of Na+ insertion/extraction sites. When used as the anode for sodium-ion batteries, the CuO/Cu exhibited an initial capacity of 580 mAh g-1, and the capacity is maintained at 200 mAh g-1 after 200 cycles at a current density of 500 mA g-1.

Novel structure formation at the bottom surface of porous anodic alumina fabricated by single step anodization process.

Science.gov (United States)

Ali, Ghafar; Ahmad, Maqsood; Akhter, Javed Iqbal; Maqbool, Muhammad; Cho, Sung Oh

2010-08-01

A simple approach for the growth of long-range highly ordered nanoporous anodic alumina film in H(2)SO(4) electrolyte through a single step anodization without any additional pre-anodizing procedure is reported. Free-standing porous anodic alumina film of 180 microm thickness with through hole morphology was obtained. A simple and single step process was used for the detachment of alumina from aluminum substrate. The effect of anodizing conditions, such as anodizing voltage and time on the pore diameter and pore ordering is discussed. The metal/oxide and oxide/electrolyte interfaces were examined by high resolution scanning transmission electron microscope. The arrangement of pores on metal/oxide interface was well ordered with smaller diameters than that of the oxide/electrolyte interface. The inter-pore distance was larger in metal/oxide interface as compared to the oxide/electrolyte interface. The size of the ordered domain was found to depend strongly upon anodizing voltage and time. (c) 2010 Elsevier Ltd. All rights reserved.

Advances in aluminum anodizing

Science.gov (United States)

Dale, K. H.

1969-01-01

White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

Solvent anode for plutonium purification

International Nuclear Information System (INIS)

Bowersox, D.F.; Fife, K.W.; Christensen, D.C.

1986-01-01

The purpose of this study is to develop a technique to allow complete oxidation of plutonium from the anode during plutonium electrorefining. This will eliminate the generation of a ''spent'' anode heel which requires further treatment for recovery. Our approach is to employ a solvent metal in the anode to provide a liquid anode pool throughout electrorefining. We use molten salts and metals in ceramic crucibles at 700 0 C. Our goal is to produce plutonium metal at 99.9% purity with oxidation and transfer of more than 98% of the impure plutonium feed metal from the anode into the salt and product phases. We have met these criteria in experiments on the 100 to 1000 g scale. We plan to scale our operations to 4 kg of feed plutonium and to optimize the process parameters

Study on the influences of reduction temperature on nickel-yttria-stabilized zirconia solid oxide fuel cell anode using nickel oxide-film electrode

Science.gov (United States)

Jiao, Zhenjun; Ueno, Ai; Suzuki, Yuji; Shikazono, Naoki

2016-10-01

In this study, the reduction processes of nickel oxide at different temperatures were investigated using nickel-film anode to study the influences of reduction temperature on the initial performances and stability of nickel-yttria-stabilized zirconia anode. Compared to conventional nickel-yttria-stabilized zirconia composite cermet anode, nickel-film anode has the advantage of direct observation at nickel-yttria-stabilized zirconia interface. The microstructural changes were characterized by scanning electron microscopy. The reduction process of nickel oxide is considered to be determined by the competition between the mechanisms of volume reduction in nickel oxide-nickel reaction and nickel sintering. Electrochemical impedance spectroscopy was applied to analyze the time variation of the nickel-film anode electrochemical characteristics. The anode performances and microstructural changes before and after 100 hours discharging and open circuit operations were analyzed. The degradation of nickel-film anode is considered to be determined by the co-effect between the nickel sintering and the change of nickel-yttria-stabilized zirconia interface bonding condition.

Photoelectric method for determination of the moment of formation of an anodic spot

International Nuclear Information System (INIS)

Barinov, V.N.; Goncharov, V.K.; Smirnov, A.V.

1986-01-01

In studying the problem of the effect of the amplitude and form of discharge current pulses on the time for transition from a diffuse discharge form to a contracted one and on the value of the threshold current I /SUB As/ for formation of an anodic spot, the authors used a photoelectric method for determination of the moment of appearance of the anodic spot based on determination of the spectral composition of the plasma at different moments of time after the beginning of discharge initiation. The photoelectric method can be used in studying emission processes on a cathode and also in those cases where both electrodes are made of the same material. An example shows synchronous oscillograms of I /SUB p/ (tau) and J /SUB i/ (tau) for copper electrodes. It is evident that during transition of the discharge to a contracted form with an anodic spot there was a sharp increase of the intensity of deexcitation of the ionic copper line. At the moment of extinction of the anodic spot, the amplitude values of J /SUB i/ (tau) corresponded to a level characteristic of the diffuse form of arc burning

Efficient reduced graphene oxide grafted porous Fe3O4 composite as a high performance anode material for Li-ion batteries.

Science.gov (United States)

Bhuvaneswari, Subramani; Pratheeksha, Parakandy Muzhikara; Anandan, Srinivasan; Rangappa, Dinesh; Gopalan, Raghavan; Rao, Tata Narasinga

2014-03-21

Here, we report facile fabrication of Fe3O4-reduced graphene oxide (Fe3O4-RGO) composite by a novel approach, i.e., microwave assisted combustion synthesis of porous Fe3O4 particles followed by decoration of Fe3O4 by RGO. The characterization studies of Fe3O4-RGO composite demonstrate formation of face centered cubic hexagonal crystalline Fe3O4, and homogeneous grafting of Fe3O4 particles by RGO. The nitrogen adsorption-desorption isotherm shows presence of a porous structure with a surface area and a pore volume of 81.67 m(2) g(-1), and 0.106 cm(3) g(-1) respectively. Raman spectroscopic studies of Fe3O4-RGO composite confirm the existence of graphitic carbon. Electrochemical studies reveal that the composite exhibits high reversible Li-ion storage capacity with enhanced cycle life and high coulombic efficiency. The Fe3O4-RGO composite showed a reversible capacity ∼612, 543, and ∼446 mA h g(-1) at current rates of 1 C, 3 C and 5 C, respectively, with a coulombic efficiency of 98% after 50 cycles, which is higher than graphite, and Fe3O4-carbon composite. The cyclic voltammetry experiment reveals the irreversible and reversible Li-ion storage in Fe3O4-RGO composite during the starting and subsequent cycles. The results emphasize the importance of our strategy which exhibited promising electrochemical performance in terms of high capacity retention and good cycling stability. The synergistic properties, (i) improved ionic diffusion by porous Fe3O4 particles with a high surface area and pore volume, and (ii) increased electronic conductivity by RGO grafting attributed to the excellent electrochemical performance of Fe3O4, which make this material attractive to use as anode materials for lithium ion storage.

Standard test method for laboratory evaluation of magnesium sacrificial anode test specimens for underground applications

CERN Document Server

American Society for Testing and Materials. Philadelphia

1997-01-01

1.1 This test method covers a laboratory procedure that measures the two fundamental performance properties of magnesium sacrificial anode test specimens operating in a saturated calcium sulfate, saturated magnesium hydroxide environment. The two fundamental properties are electrode (oxidation potential) and ampere hours (Ah) obtained per unit mass of specimen consumed. Magnesium anodes installed underground are usually surrounded by a backfill material that typically consists of 75 % gypsum (CaSO4·2H2O), 20 % bentonite clay, and 5 % sodium sulfate (Na2SO4). The calcium sulfate, magnesium hydroxide test electrolyte simulates the long term environment around an anode installed in the gypsum-bentonite-sodium sulfate backfill. 1.2 This test method is intended to be used for quality assurance by anode manufacturers or anode users. However, long term field performance properties may not be identical to property measurements obtained using this laboratory test. Note 1—Refer to Terminology G 15 for terms used ...

Enhanced cycle stability of micro-sized Si/C anode material with low carbon content fabricated via spray drying and in situ carbonization

Energy Technology Data Exchange (ETDEWEB)

Wang, Dingsheng; Gao, Mingxia, E-mail: gaomx@zju.edu.cn; Pan, Hongge; Liu, Yongfeng; Wang, Junhua; Li, Shouquan; Ge, Hongwei

2014-08-01

Highlights: • Micro-sized Si/C composites were fabricated via. spray drying and carbonization. • Multi-morphology carbon was formed in the Si/C composites. • Si/C composite with 5.6 wt.% C provides significant improved cycling stability. • Multi-morphology carbon plays effective role in improving the electrochemical property. • The method provides potential for mass production of superior Si-based anode materials. - Abstract: Micro-sized Si/C composites with in situ introduced carbon of multi-morphology were fabricated via spray drying a suspension of commercial micro-sized Si and citric acid followed by a carbonization. Different ratios of Si to citric acid were used to optimize the composition and structure of the composites and thus the electrochemical performance. Carbon flakes including crooked and flat ones were well dispersed in between the Si particles, forming Si/C composites. Floc-like carbon layers and carbon fragments were also found to cover partially the Si particles. The Si/C composite with a low carbon content of 5.6 wt.% provides an initial reversible capacity of 2700 mA h/g and a capacity of 1860 mA h/g after 60 cycles at a current density of 100 mA/g as anode material for lithium-ion batteries (LIBs), which are much higher than those of pristine Si and the Si/C composites with higher carbon content. The mechanism of the enhancement of electrochemical performance of the micro-sized Si/C composite is discussed. The fabrication method and the structure design of the composites offer valuable potential in developing adaptable Si-based anode materials for industrial applications.

Characterisation and behaviour of Ti/TiO2/noble metal anodes

International Nuclear Information System (INIS)

Gueneau de Mussy, Jean-Paul; Macpherson, Julie V.; Delplancke, Jean-Luc

2003-01-01

The morphology, composition and the electrical and electrochemical behaviour of the anodic microporous layer, prepared by the galvanostatic anodisation of Ti after sparking, followed by galvanostatic deposition of Pt or Ir have been investigated. These electrodes are proposed to function as dimensionally stable anodes (DSAs). For Ti/TiO 2 /Pt electrodes, Pt is deposited within some of the micropores of the oxide film. In contrast, for Ti/TiO 2 /Ir, the metal is deposited preferentially on the top surface. This difference is thought to result from the position of the metal deposition potential with respect to the flat band potential of n-TiO 2 . Optical imaging of both types of DSA suggests that only a few sites on the surface are responsible for electron exchange at the DSA-electrolyte interface. C-AFM measurements of Ti/TiO 2 /Pt samples subjected to long-term anodic polarisation, suggest that the Ti-noble metal contact is progressively insulated by thickening of the TiO 2 barrier layer, promoting passivation of the DSA. For Ir coated anodes, catalytic activity is directly related to the presence of Ir and to the stability of the catalytic oxide layer. Under Cu electrowinning conditions, the electrochemically formed hydrated Ir oxide was found to be catalytically less stable, than the iridium oxide film subjected to a heat treatment

In-situ grown CNTs modified SiO2/C composites as anode with improved cycling stability and rate capability for lithium storage