Method of processing a substrate

DOEpatents

Babayan, Steven E [Huntington Beach, CA; Hicks, Robert F [Los Angeles, CA

2008-02-12

The invention is embodied in a plasma flow device or reactor having a housing that contains conductive electrodes with openings to allow gas to flow through or around them, where one or more of the electrodes are powered by an RF source and one or more are grounded, and a substrate or work piece is placed in the gas flow downstream of the electrodes, such that said substrate or work piece is substantially uniformly contacted across a large surface area with the reactive gases emanating therefrom. The invention is also embodied in a plasma flow device or reactor having a housing that contains conductive electrodes with openings to allow gas to flow through or around them, where one or more of the electrodes are powered by an RF source and one or more are grounded, and one of the grounded electrodes contains a means of mixing in other chemical precursors to combine with the plasma stream, and a substrate or work piece placed in the gas flow downstream of the electrodes, such that said substrate or work piece is contacted by the reactive gases emanating therefrom. In one embodiment, the plasma flow device removes organic materials from a substrate or work piece, and is a stripping or cleaning device. In another embodiment, the plasma flow device kills biological microorganisms on a substrate or work piece, and is a sterilization device. In another embodiment, the plasma flow device activates the surface of a substrate or work piece, and is a surface activation device. In another embodiment, the plasma flow device etches materials from a substrate or work piece, and is a plasma etcher. In another embodiment, the plasma flow device deposits thin films onto a substrate or work piece, and is a plasma-enhanced chemical vapor deposition device or reactor.

Device for providing high-intensity ion or electron beam

DOEpatents

McClanahan, Edwin D.; Moss, Ronald W.

1977-01-01

A thin film of a low-thermionic-work-function material is maintained on the cathode of a device for producing a high-current, low-pressure gas discharge by means of sputter deposition from an auxiliary electrode. The auxiliary electrode includes a surface with a low-work-function material, such as thorium, uranium, plutonium or one of the rare earth elements, facing the cathode but at a disposition and electrical potential so as to extract ions from the gas discharge and sputter the low-work-function material onto the cathode. By continuously replenishing the cathode film, high thermionic emissions and ion plasmas can be realized and maintained over extended operating periods.

Performance-Enhanced Activated Carbon Electrodes for Supercapacitors Combining Both Graphene-Modified Current Collectors and Graphene Conductive Additive.

PubMed

Wang, Rubing; Qian, Yuting; Li, Weiwei; Zhu, Shoupu; Liu, Fengkui; Guo, Yufen; Chen, Mingliang; Li, Qi; Liu, Liwei

2018-05-15

Graphene has been widely used in the active material, conductive agent, binder or current collector for supercapacitors, due to its large specific surface area, high conductivity, and electron mobility. However, works simultaneously employing graphene as conductive agent and current collector were rarely reported. Here, we report improved activated carbon (AC) electrodes (AC@G@NiF/G) simultaneously combining chemical vapor deposition (CVD) graphene-modified nickel foams (NiF/Gs) current collectors and high quality few-layer graphene conductive additive instead of carbon black (CB). The synergistic effect of NiF/Gs and graphene additive makes the performances of AC@G@NiF/G electrodes superior to those of electrodes with CB or with nickel foam current collectors. The performances of AC@G@NiF/G electrodes show that for the few-layer graphene addition exists an optimum value around 5 wt %, rather than a larger addition of graphene, works out better. A symmetric supercapacitor assembled by AC@G@NiF/G electrodes exhibits excellent cycling stability. We attribute improved performances to graphene-enhanced conductivity of electrode materials and NiF/Gs with 3D graphene conductive network and lower oxidation, largely improving the electrical contact between active materials and current collectors.

Performance-Enhanced Activated Carbon Electrodes for Supercapacitors Combining Both Graphene-Modified Current Collectors and Graphene Conductive Additive

PubMed Central

Wang, Rubing; Qian, Yuting; Li, Weiwei; Zhu, Shoupu; Liu, Fengkui; Guo, Yufen; Chen, Mingliang; Li, Qi; Liu, Liwei

2018-01-01

Graphene has been widely used in the active material, conductive agent, binder or current collector for supercapacitors, due to its large specific surface area, high conductivity, and electron mobility. However, works simultaneously employing graphene as conductive agent and current collector were rarely reported. Here, we report improved activated carbon (AC) electrodes (AC@G@NiF/G) simultaneously combining chemical vapor deposition (CVD) graphene-modified nickel foams (NiF/Gs) current collectors and high quality few-layer graphene conductive additive instead of carbon black (CB). The synergistic effect of NiF/Gs and graphene additive makes the performances of AC@G@NiF/G electrodes superior to those of electrodes with CB or with nickel foam current collectors. The performances of AC@G@NiF/G electrodes show that for the few-layer graphene addition exists an optimum value around 5 wt %, rather than a larger addition of graphene, works out better. A symmetric supercapacitor assembled by AC@G@NiF/G electrodes exhibits excellent cycling stability. We attribute improved performances to graphene-enhanced conductivity of electrode materials and NiF/Gs with 3D graphene conductive network and lower oxidation, largely improving the electrical contact between active materials and current collectors. PMID:29762528

All-phosphorus flexible devices with non-collinear electrodes: a first principles study.

PubMed

Li, Junjun; Ruan, Lufeng; Wu, Zewen; Zhang, Guiling; Wang, Yin

2018-03-07

With the continuous expansion of the family of two-dimensional (2D) materials, flexible electronics based on 2D materials have quickly emerged. Theoretically, predicting the transport properties of the flexible devices made up of 2D materials using first principles is of great importance. Using density functional theory combined with the non-equilibrium Green's function formalism, we calculated the transport properties of all-phosphorus flexible devices with non-collinear electrodes, and the results predicted that the device with compressed metallic phosphorene electrodes sandwiching a P-type semiconducting phosphorene shows a better and robust conducting behavior against the bending of the semiconducting region when the angle between the two electrodes is less than 45°, which indicates that this system is very promising for flexible electronics. The calculation of a quantum transport system with non-collinear electrodes demonstrated in this work will provide more interesting information on mesoscopic material systems and related devices.

High-capacity FeTiO3/C negative electrode for sodium-ion batteries with ultralong cycle life

NASA Astrophysics Data System (ADS)

Ding, Changsheng; Nohira, Toshiyuki; Hagiwara, Rika

2018-06-01

The development of electrode materials which improve both the energy density and cycle life is one of the most challenging issues facing the practical application of sodium-ion batteries today. In this work, FeTiO3/C nanoparticles are synthesized as negative electrode materials for sodium-ion batteries. The electrochemical performance and charge-discharge mechanism of the FeTiO3/C negative electrode are investigated in an ionic liquid electrolyte at 90 °C. The FeTiO3/C negative electrode delivers a high reversible capacity of 403 mAh g-1 at a current rate of 10 mA g-1, and exhibits high rate capability and excellent cycling stability for up to 2000 cycles. The results indicate that FeTiO3/C is a promising negative electrode material for sodium-ion batteries.

Effects of Carbonization Temperature on Nature of Nanostructured Electrode Materials Derived from Fe-MOF for Supercapacitors

NASA Astrophysics Data System (ADS)

Sui, Yanwei; Zhang, Dongling; Han, Yongpeng; Sun, Zhi; Qi, Jiqiu; Wei, Fuxiang; He, Yezeng; Meng, Qingkun

2018-05-01

This work successfully demonstrates various temperature carbonization of iron based metal organic framework to derive electrode materials for supercapacitors. Furthermore, impacts of calcined temperatures on the nature of as-prepared products are reported, and samples obtained at 300, 400, 500, 600 and 700 °C were investigated respectively. The products reveals excellent electrochemical performance. Carbonized at 600 °C, the composite materials display the highest specific capacitance of 972 F/g at a current density of 1 A/g. Carbonized at 500 °C, the capacitance retention of materials reach up to 93%. The high specific capacitance and excellent cyclic stability of the developed materials would exhibit nice prospect for the practical utilization of electrode materials.

Amperometric Detection in Microchip Electrophoresis Devices: Effect of Electrode Material and Alignment on Analytical Performance

PubMed Central

Fischer, David J.; Hulvey, Matthew K.; Regel, Anne R.; Lunte, Susan M.

2012-01-01

The fabrication and evaluation of different electrode materials and electrode alignments for microchip electrophoresis with electrochemical (EC) detection is described. The influences of electrode material, both metal and carbon-based, on sensitivity and limits of detection (LOD) were examined. In addition, the effects of working electrode alignment on analytical performance (in terms of peak shape, resolution, sensitivity, and LOD) were directly compared. Using dopamine (DA), norepinephrine (NE), and catechol (CAT) as test analytes, it was found that pyrolyzed photoresist electrodes with end-channel alignment yielded the lowest limit of detection (35 nM for DA). In addition to being easier to implement, end-channel alignment also offered better analytical performance than off-channel alignment for the detection of all three analytes. In-channel electrode alignment resulted in a 3.6-fold reduction in peak skew and reduced peak tailing by a factor of 2.1 for catechol in comparison to end-channel alignment. PMID:19802847

Construction and Testing of Coin Cells of Lithium Ion Batteries

PubMed Central

Kayyar, Archana; Huang, Jiajia; Samiee, Mojtaba; Luo, Jian

2012-01-01

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles1 or even electrical grid stabilization systems2. All these applications simulate a dramatic increase in the research and development of battery materials3-7, including new materials3,8, doping9, nanostructuring10-13, coatings or surface modifications14-17 and novel binders18. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students. In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials14. Third, better binders (other than PVDF) have also developed and used18. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes7. PMID:22895280

Construction and testing of coin cells of lithium ion batteries.

PubMed

Kayyar, Archana; Huang, Jiajia; Samiee, Mojtaba; Luo, Jian

2012-08-02

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles or even electrical grid stabilization systems. All these applications simulate a dramatic increase in the research and development of battery materials, including new materials, doping, nanostructuring, coatings or surface modifications and novel binders. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students. In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials. Third, better binders (other than PVDF) have also developed and used. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes.

Electrochemical micro sensor

DOEpatents

Setter, Joseph R.; Maclay, G. Jordan

1989-09-12

A micro-amperometric electrochemical sensor for detecting the presence of a pre-determined species in a fluid material is disclosed. The sensor includes a smooth substrate having a thin coating of solid electrolytic material deposited thereon. The working and counter electrodes are deposited on the surface of the solid electrolytic material and adhere thereto. Electrical leads connect the working and counter electrodes to a potential source and an apparatus for measuring the change in an electrical signal caused by the electrochemical oxidation or reduction of the species. Alternatively, the sensor may be fabricated in a sandwich structure and also may be cylindrical, spherical or other shapes.

Regulated Breathing Effect of Silicon Negative Electrode for Dramatically Enhanced Performance of Li-Ion Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Xingcheng; Zhou, Weidong; Kim, Youngnam

Si is an attractive negative electrode material for lithium ion batteries due to its high specifi c capacity (≈3600 mAh g –1 ). However, the huge volume swelling and shrinking during cycling, which mimics a breathing effect at the material/electrode/cell level, leads to several coupled issues including fracture of Si particles, unstable solid electrolyte interphase, and low Coulombic effi ciency. In this work, the regulation of the breathing effect is reported by using Si–C yolk–shell nanocomposite which has been well-developed by other researchers. The focus is on understanding how the nanoscaled materials design impacts the mechanical and electrochemical response atmore » electrode level. For the fi rst time, it is possible to observe one order of magnitude of reduction on breathing effect at the electrode level during cycling: the electrode thickness variation reduced down to 10%, comparing with 100% in the electrode with Si nanoparticles as active materials. The Si–C yolk–shell nanocomposite electrode exhibits excellent capacity retention and high cycle effi ciency. In situ transmission electron microscopy and fi nite element simulations consistently reveals that the dramatically enhanced performance is associated with the regulated breathing of the Si in the new composite, therefore the suppression of the overall electrode expansion.« less

A Comparative evaluation of Graphene oxide based materials for Electrochemical non-enzymatic sensing of Curcumin

NASA Astrophysics Data System (ADS)

Dey, Nibedita; Devasena, T.; Sivalingam, Tamilarasu

2018-02-01

This work reports a comparative study on the development of a sensitive voltammetric method for the assay of diferuloylmethane which is fabricated using cost-effective sensing material graphene oxide (GO modified electrode) and reduced graphene oxide (rGO modified electrode) modified on glassy carbon electrode respectively. The prepared materials were characterized using SEM, XRD, FTIR, and Raman techniques to understand the formation. Between the both modified electrodes, rGO modified electrode demonstrated a lower limit detection of 0.9 pM and good signal quality. But, the better linear dynamic range for detection was found to be 1 nm to 100 nM for GO and 0.1 nM to 10 nM for rGO modified electrodes respectively. The repeatability is checked for seven cycles and interference studies were also performed for checking the sensors’ selectivity to curcumin. rGO modified electrode and GO modified electrode both shows specific signals for Diferuloylmethane under conditions similar to physiology. But, with better properties over GO modified electrode, rGO modified electrode is suggested a better candidate for real-time usability in sensing. The detection limit reported is the lowest till date for the given plant drug using any sensing assay.

Sol-gel derived electrode materials for supercapacitor applications

NASA Astrophysics Data System (ADS)

Lin, Chuan

1998-12-01

Electrochemical capacitors have been receiving increasing interest in recent years for use in energy storage systems because of their high energy and power density and long cycle lifes. Possible applications of electrochemical capacitors include high power pulsed lasers, hybrid power system for electric vehicles, etc. In this dissertation, the preparation of electrode materials for use as electrochemical capacitors has been studied using the sol-gel process. The high surface area electrode materials explored in this work include a synthetic carbon xerogel for use in a double-layer capacitor, a cobalt oxide xerogel for use in a pseudocapacitor, and a carbon-ruthenium xerogel composite, which utilizes both double-layer and faradaic capacitances. The preparation conditions of these materials were investigated in detail to maximize the surface area and optimize the pore size so that more energy could be stored while minimizing mass transfer limitations. The microstructures of the materials were also correlated with their performance as electrochemical capacitors to improve their energy and power densities. Finally, an idealistic mathematical model, including both double-layer and faradaic processes, was developed and solved numerically. This model can be used to perform the parametric studies of an electrochemical capacitor so as to gain a better understanding of how the capacitor works and also how to improve cell operations and electrode materials design.

The effects of electron and hole transport layer with the electrode work function on perovskite solar cells

NASA Astrophysics Data System (ADS)

Deng, Quanrong; Li, Yiqi; Chen, Lian; Wang, Shenggao; Wang, Geming; Sheng, Yonglong; Shao, Guosheng

2016-09-01

The effects of electron and hole transport layer with the electrode work function on perovskite solar cells with the interface defects were simulated by using analysis of microelectronic and photonic structures-one-dimensional (AMPS-1D) software. The simulation results suggest that TiO2 electron transport layer provides best device performance with conversion efficiency of 25.9% compared with ZnO and CdS. The threshold value of back electrode work function for Spiro-OMeTAD, NiO, CuI and Cu2O hole transport layer are calculated to be 4.9, 4.8, 4.7 and 4.9 eV, respectively, to reach the highest conversion efficiency. The mechanisms of device physics with various electron and hole transport materials are discussed in details. The device performance deteriorates gradually as the increased density of interface defects located at ETM/absorber or absorber/HTM. This research results can provide helpful guidance for materials and metal electrode choice for perovskite solar cells.

Synthesis of Ammonia-Assisted Porous Nickel Ferrite (NiFe₂O₄) Nanostructures as an Electrode Material for Supercapacitors.

PubMed

Bhojane, Prateek; Sharma, Alfa; Pusty, Manojit; Kumar, Yogendra; Sen, Somaditya; Shirage, Parasharam

2017-02-01

In this work, we report a low cost, facile synthesis method for Nickel ferrite (NiFe₂O₄) nanostructures obtained by chemical bath deposition method for alternate transition metal oxide electrode material as a solution for clean energy. We developed a template free ammonia assisted method for obtaining porous structure which offering better supercapacitive performance of NiFe₂O₄ electrode material than previously reported for pure NiFe₂O₄. Here we explore the physical characterizations X-ray diffraction, FESEM, HRTEM performed to under-stand its crystal structure and morphology as well as the electrochemical measurements was performed to understand the electrochemical behaviour of the material. Here ammonia plays an important role in governing the structure/morphology of the material and enhances the electrochemical performance. The specific capacitance of 541 Fg⁻¹ is achieved at 2 mVs⁻¹ scan rate which is highest for the pure NiFe₂O₄ electrode material without using any addition of carbon based material, heterostructure or template based method.

Electrochemical and Capacitive Properties of Carbon Dots/Reduced Graphene Oxide Supercapacitors.

PubMed

Dang, Yong-Qiang; Ren, Shao-Zhao; Liu, Guoyang; Cai, Jiangtao; Zhang, Yating; Qiu, Jieshan

2016-11-14

There is much recent interest in graphene-based composite electrode materials because of their excellent mechanical strengths, high electron mobilities, and large specific surface areas. These materials are good candidates for applications in supercapacitors. In this work, a new graphene-based electrode material for supercapacitors was fabricated by anchoring carbon dots (CDs) on reduced graphene oxide (rGO). The capacitive properties of electrodes in aqueous electrolytes were systematically studied by galvanostatic charge-discharge measurements, cyclic voltammetry, and electrochemical impedance spectroscopy. The capacitance of rGO was improved when an appropriate amount of CDs were added to the material. The CD/rGO electrode exhibited a good reversibility, excellent rate capability, fast charge transfer, and high specific capacitance in 1 M H₂SO₄. Its capacitance was as high as 211.9 F/g at a current density of 0.5 A/g. This capacitance was 74.3% higher than that of a pristine rGO electrode (121.6 F/g), and the capacitance of the CD/rGO electrode retained 92.8% of its original value after 1000 cycles at a CDs-to-rGO ratio of 5:1.

Oriented Polyaniline Nanowire Arrays Grown on Dendrimer (PAMAM) Functionalized Multiwalled Carbon Nanotubes as Supercapacitor Electrode Materials.

PubMed

Jin, Lin; Jiang, Yu; Zhang, Mengjie; Li, Honglong; Xiao, Linghan; Li, Ming; Ao, Yuhui

2018-04-19

At present, PANI/MWNT composites have been paid more attention as promising electrode materials in supercapacitors. Yet some shortcomings still limit the widely application of PANI/MWNT electrolytes. In this work, in order to improve capacitance ability and long-term stability of electrode, a multi-amino dendrimer (PAMAM) had been covalently linked onto multi-walled carbon nanotubes (MWNT) as a bridge to facilitating covalent graft of polyaniline (PANI), affording P-MWNT/PANI electrode composites for supercapacitor. Surprisingly, ordered arrays of PANI nanowires on MWNT (setaria-like morphology) had been observed by scanning electron microscopy (SEM). Electrochemical properties of P-MWNT/PANI electrode had been characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge technique. The specific capacitance and long cycle life of P-MWNT-PANI electrode material were both much higher than MWNT/PANI. These interesting results indicate that multi-amino dendrimer, PAMAM, covalently linked on MWNT provides more reaction sites for in-situ polymerization of ordered PANI, which could efficiently shorten the ion diffusion length in electrolytes and lead to making fully use of conducting materials.

High performance aqueous symmetric supercapacitors based on advanced carbon electrodes and hydrophilic poly(vinylidene fluoride) porous separator

NASA Astrophysics Data System (ADS)

Xie, Qinxing; Huang, Xiaolin; Zhang, Yufeng; Wu, Shihua; Zhao, Peng

2018-06-01

The main components of a supercapacitor include two electrodes, electrolyte, and a separator, which are all essential to specify the energy storage capability of the device. In this work, two kinds of porous carbon materials have been fabricated via different routes using pomelo peel as raw material. The specific surface area are 1187 m2 g-1 for the nanosized worm-like carbon, and 1744 m2 g-1 for the nitrogen-enriched microsized carbon. Both carbon materials demonstrate excellent energy storage capability as electrodes for aqueous supercapacitors. According to the three-electrode measurements, the worm-like carbon exhibits a high specific capacitance of 316 F g-1 at 0.2 A g-1 in 6 M KOH, while the other exhibits 471 F g-1 due to the highly enriched nitrogen atoms in structure. In addition, two-electrode coin-type cells have been assembled with the carbon materials as electrodes and hydrophilic poly(vinylidene fluoride) porous membrane as the separator. The assembled cells exhibit high specific capacitances, excellent rate performance and superior cycling durability because of a synergistic effect of the high performance carbon electrodes and hydrophilic porous separator.

Pseudocapacitive and hierarchically ordered porous electrode materials supercapacitors

NASA Astrophysics Data System (ADS)

Saruhan, B.; Gönüllü, Y.; Arndt, B.

2013-05-01

Commercially available double layer capacitors store energy in an electrostatic field. This forms in the form of a double layer by charged particles arranged on two electrodes consisting mostly of active carbon. Such double layer capacitors exhibit a low energy density, so that components with large capacity according to large electrode areas are required. Our research focuses on the development of new electrode materials to realize the production of electrical energy storage systems with high energy density and high power density. Metal oxide based electrodes increase the energy density and the capacitance by addition of pseudo capacitance to the static capacitance present by the double layer super-capacitor electrodes. The so-called hybrid asymmetric cell capacitors combine both types of energy storage in a single component. In this work, the production routes followed in our laboratories for synthesis of nano-porous and aligned metal oxide electrodes using the electrochemical and sputter deposition as well as anodization methods will be described. Our characterisation studies concentrate on electrodes having redox metal-oxides (e.g. MnOx and WOx) and hierarchically aligned nano-porous Li-doped TiO2-NTs. The material specific and electrochemical properties achieved with these electrodes will be presented.

Facile synthesis of nanostructured transition metal oxides as electrodes for Li-ion batteries

NASA Astrophysics Data System (ADS)

Opra, Denis P.; Gnedenkov, Sergey V.; Sokolov, Alexander A.; Minaev, Alexander N.; Kuryavyi, Valery G.; Sinebryukhov, Sergey L.

2017-09-01

At all times, energy storage is one of the greatest scientific challenge. Recently, Li-ion batteries are under special attention due to high working voltage, long cycle life, low self-discharge, reliability, no-memory effect. However, commercial LIBs usage in medium- and large-scale energy storage are limited by the capacity of lithiated metal oxide cathode and unsafety of graphite anode at high-rate charge. In this way, new electrode materials with higher electrochemical performance should be designed to satisfy a requirement in both energy and power. As it known, nanostructured transition metal oxides are promising electrode materials because of their elevated specific capacity and high potential vs. Li/Li+. In this work, the perspective of an original facile technique of pulsed high-voltage plasma discharge in synthesis of nanostructured transition metal oxides as electrodes for lithium-ion batteries has been demonstrated.

Temperature-dependent electrochemical capacitive performance of the α-Fe2O3 hollow nanoshuttles as supercapacitor electrodes.

PubMed

Zheng, Xin; Yan, Xiaoqin; Sun, Yihui; Yu, Yinsheng; Zhang, Guangjie; Shen, Yanwei; Liang, Qijie; Liao, Qingliang; Zhang, Yue

2016-03-15

The design and optimization of supercapacitors electrodes nanostructures are critically important since the properties of supercapacitors can be dramatically enhanced by tunable ion transport channels. Herein, we demonstrate high-performance supercapacitor electrodes materials based on α-Fe2O3 by rationally designing the electrode microstructure. The large solid-liquid reaction interfaces induced by hollow nanoshuttle-like structures not only provide more active sites for faradic reactions but also facilitate the diffusion of the electrolyte into electrodes. These result in the optimized electrodes with high capacitance of 249 F g(-1) at a discharging current density of 0.5 A g(-1) as well as good cycle stability. In addition, the relationship between charge storage and the operating temperature has been researched. The specific capacitance has no significant change when the working temperature increased from 20 °C to 60 °C (e.g. 203 F g(-1) and 234 F g(-1) at 20 °C and 60 °C, respectively), manifesting the electrodes can work stably in a wide temperature range. These findings here elucidate the α-Fe2O3 hollow nanoshuttles can be applied as a promising supercapacitor electrode material for the efficient energy storage at various potential temperatures. Copyright © 2015 Elsevier Inc. All rights reserved.

Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review.

PubMed

Jia, Baoping; Zhang, Wei

2016-12-01

As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed.

Boron-Doped Nanocrystalline Diamond Electrodes for Neural Interfaces: In vivo Biocompatibility Evaluation

PubMed Central

Alcaide, María; Taylor, Andrew; Fjorback, Morten; Zachar, Vladimir; Pennisi, Cristian P.

2016-01-01

Boron-doped nanocrystalline diamond (BDD) electrodes have recently attracted attention as materials for neural electrodes due to their superior physical and electrochemical properties, however their biocompatibility remains largely unexplored. In this work, we aim to investigate the in vivo biocompatibility of BDD electrodes in relation to conventional titanium nitride (TiN) electrodes using a rat subcutaneous implantation model. High quality BDD films were synthesized on electrodes intended for use as an implantable neurostimulation device. After implantation for 2 and 4 weeks, tissue sections adjacent to the electrodes were obtained for histological analysis. Both types of implants were contained in a thin fibrous encapsulation layer, the thickness of which decreased with time. Although the level of neovascularization around the implants was similar, BDD electrodes elicited significantly thinner fibrous capsules and a milder inflammatory reaction at both time points. These results suggest that BDD films may constitute an appropriate material to support stable performance of implantable neural electrodes over time. PMID:27013949

Anode energy transfer in a transient arc

NASA Astrophysics Data System (ADS)

Valensi, F.; Ratovoson, P.; Razafinimanana, M.; Gleizes, A.

2017-04-01

This work deals with experimental investigation of a transient arc. Arc configuration and electrode erosion were studied in order to quantify the energy transfer to the electrodes as a function of maximal current, time constant and electrodes material. Experiments with two consecutive arcs allow demonstrating non stationary behaviour of the arc electrode interaction. This is due to the fact that while the duration of the experiments is far larger than plasma phenomena time constants, it is comparable to those of electrode heating and melting processes.

Novel electrode systems for amperometric sensing: the case of titanium

NASA Astrophysics Data System (ADS)

Terzi, F.; Pigani, L.; Zanardi, C.; Zanfrognini, B.; Ruggeri, S.; Maccaferri, G.; Seeber, R.

2014-10-01

After working for years on organic materials, e.g., polythiophenes and relevant composites with metal nanoparticles, we shifted our attention to unusual metals, chosen as candidates to effective amperometric sensing on the basis of the atomic structure and crystalline properties. The present contribution aims at proposing an electrode material rarely employed in electroanalysis, namely Ti. We have experimented that the peculiar nature of Ti leads to electrochemical behavior quite different with respect to the conventional electrode materials, including those based on TiO2 (nano)particles. Our work focuses on the determination of strong oxidizing species, namely H2O2 and HClO, and noble metal ions, namely Au(III). Strong oxidizing species are commodity chemicals employed in a number of different industrial processes, in which usually high concentration levels should be monitored. The procedures proposed have been successfully applied also in complex matrices, such as detergent samples. As to Au(III) determination, it also constitutes a crucial tool in order to increase the efficiency of hydrometallurgic processes and of the recovery of precious materials from electronic waste. Ti electrodes allow the determination of dissolved Au species in the presence of other metal ions. In any cases the electrodes exhibit reproducible and repeatable electrochemical responses, even in the presence of high concentration of organic fouling species typical of bio-sorption processes.

Thermoelectricity in fullerene-metal heterojunctions.

PubMed

Yee, Shannon K; Malen, Jonathan A; Majumdar, Arun; Segalman, Rachel A

2011-10-12

Thermoelectricty in heterojunctions, where a single-molecule is trapped between metal electrodes, has been used to understand transport properties at organic-inorganic interfaces. (1) The transport in these systems is highly dependent on the energy level alignment between the molecular orbitals and the Fermi level (or work function) of the metal contacts. To date, the majority of single-molecule measurements have focused on simple small molecules where transport is dominated through the highest occupied molecular orbital. (2, 3) In these systems, energy level alignment is limited by the absence of electrode materials with low Fermi levels (i.e., large work functions). Alternatively, more controllable alignment between molecular orbitals and the Fermi level can be achieved with molecules whose transport is dominated by the lowest unoccupied molecular orbital (LUMO) because of readily available metals with lower work functions. Herein, we report molecular junction thermoelectric measurements of fullerene molecules (i.e., C(60), PCBM, and C(70)) trapped between metallic electrodes (i.e., Pt, Au, Ag). Fullerene junctions demonstrate the first strongly n-type molecular thermopower corresponding to transport through the LUMO, and the highest measured magnitude of molecular thermopower to date. While the electronic conductance of fullerenes is highly variable, due to fullerene's variable bonding geometries with the electrodes, the thermopower shows predictable trends based on the alignment of the LUMO with the work function of the electrodes. Both the magnitude and trend of the thermopower suggest that heterostructuring organic and inorganic materials at the nanoscale can further enhance thermoelectric performance, therein providing a new pathway for designing thermoelectric materials.

Fabrication and surface characterization of composite refractory compounds suitable for thermionic converters

NASA Technical Reports Server (NTRS)

Davis, P. R.; Swanson, L. W.

1979-01-01

The techniques of fabricating and characterizing the surface properties of electrode materials were investigated. The basic surface properties of these materials were studied with respect to their utilization as thermionic energy converter electrodes. Emphasis was placed on those factors (e.g, cesium disorption kinetic and mechanisms of low work function production) which are of primary concern to thermionic converter performance.

Assessment of Wound Therapy Systems.

DTIC Science & Technology

1983-10-06

electrodes in vinyl foam (mfr: Healthco) (for potential measurements), sticky carbon-impregnated pads (commonly used * for transcutaneous electrical nerve...improved product is a conductive material, applied to the target surface as a liquid (in which an electrode can be embedded); this liquid material then gels... conducted with two grades of collagen hydrolysate (gelatins) which have been cross-linked in situ from water solu- tion. This work clearly shows that stable

EME 192 Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mora, J.; Pascall, A.; Dudoff, J.

I spent the quarter working in Lawrence Livermore National Laboratory’s (LLNL) Materials Engineering Division. The group I have been working with (I’ve been here for two summers already) focuses on advanced manufacturing techniques such as stereolithography, electrophoretic deposition, and the printing of silicon based inks. Part of the goal of what is done in our group is to create designer materials not by altering the composition but by altering the micro-architecture. Our technology can create shapes that are not possible with traditional manufacturing techniques. This allows us to create structures that are light, yet very strong and stiff. It alsomore » allows us to create materials with property gradients. In other words, we can make structures and parts that are stronger in some locations than others. I have been working with electrophoretic deposition for the duration of my stay and have focused on advancing the technology from a thin-film technique to a true additive manufacturing paradigm. Put succinctly, electrophoretic deposition is the deposition of particles in suspension with electric fields. Particles have a potential on the surface which allows them to be driven to an electrode using an electric field. The particles then deposit onto the conductive regions of the substrate, traditionally, the entire surface. Electrophoretic deposition is powerful in that it can handle a wide variety of materials (ceramics, metals, bacteria), create material gradients in the deposits, and create layered deposition of multiple materials. A drawback of traditional electrophoretic deposition is that patterned deposits are only possible with a non-reconfigurable patterned electrode. A technique was developed at LLNL that allows for the arbitrary patterning of the electric field using photoconductive electrodes and light. This way, you can create interesting shapes and reconfigure the pattern of the deposit using the same electrode. A photoconductive electrode is made by hydrothermally growing titania nanorods onto a transparent current collector. A photomask is used to block incoming some light and only allow the desired pattern of light through. The photoconductive electrode then activates when and where the light hits, once an electric field is applied. Particles will migrate to the areas of illumation and deposit.« less

Design of nanostructured-based glucose biosensors

NASA Astrophysics Data System (ADS)

Komirisetty, Archana; Williams, Frances; Pradhan, Aswini; Konda, Rajini B.; Dondapati, Hareesh; Samantaray, Diptirani

2012-04-01

This paper presents the design of glucose sensors that will be integrated with advanced nano-materials, bio-coatings and electronics to create novel devices that are highly sensitive, inexpensive, accurate, and reliable. In the work presented, a glucose biosensor and its fabrication process flow have been designed. The device is based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nano-rods. Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability which are very crucial parameters to achieve high sensitivity. Amperometric enzyme electrodes based on glucose oxidase (GOx) are used due to their stability and high selectivity to glucose. The device also consists of silicon dioxide and titanium layers as well as platinum working and counter electrodes and a silver/silver chloride reference electrode. Currently, the biosensors are being fabricated using the process flow developed. Once completed, the sensors will be bio-functionalized and tested to characterize their performance, including their sensitivity and stability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pezeshki, Alan M.; Sacci, Robert L.; Veith, Gabriel M.

Here, we demonstrate a novel method to accelerate electrode degradation in redox flow batteries and apply this method to the all-vanadium chemistry. Electrode performance degradation occurred seven times faster than in a typical cycling experiment, enabling rapid evaluation of materials. This method also enables the steady-state study of electrodes. In this manner, it is possible to delineate whether specific operating conditions induce performance degradation; we found that both aggressively charging and discharging result in performance loss. Post-mortem x-ray photoelectron spectroscopy of the degraded electrodes was used to resolve the effects of state of charge (SoC) and current on the electrodemore » surface chemistry. For the electrode material tested in this work, we found evidence that a loss of oxygen content on the negative electrode cannot explain decreased cell performance. Furthermore, the effects of decreased electrode and membrane performance on capacity fade in a typical cycling battery were decoupled from crossover; electrode and membrane performance decay were responsible for a 22% fade in capacity, while crossover caused a 12% fade.« less

Roll-to-Roll Laser-Printed Graphene-Graphitic Carbon Electrodes for High-Performance Supercapacitors.

PubMed

Kang, Sangmin; Lim, Kyungmi; Park, Hyeokjun; Park, Jong Bo; Park, Seong Chae; Cho, Sung-Pyo; Kang, Kisuk; Hong, Byung Hee

2018-01-10

Carbon electrodes including graphene and thin graphite films have been utilized for various energy and sensor applications, where the patterning of electrodes is essentially included. Laser scribing in a DVD writer and inkjet printing were used to pattern the graphene-like materials, but the size and speed of fabrication has been limited for practical applications. In this work, we devise a simple strategy to use conventional laser-printer toner materials as precursors for graphitic carbon electrodes. The toner was laser-printed on metal foils, followed by thermal annealing in hydrogen environment, finally resulting in the patterned thin graphitic carbon or graphene electrodes for supercapacitors. The electrochemical cells made of the graphene-graphitic carbon electrodes show remarkably higher energy and power performance compared to conventional supercapacitors. Furthermore, considering the simplicity and scalability of roll-to-roll (R2R) electrode patterning processes, the proposed method would enable cheaper and larger-scale synthesis and patterning of graphene-graphitic carbon electrodes for various energy applications in the future.

Covalently functionalized single-walled carbon nanotubes and graphene composite electrodes for pseudocapacitor application

NASA Astrophysics Data System (ADS)

Le Barny, Pierre; Servet, Bernard; Campidelli, Stéphane; Bondavalli, Paolo; Galindo, Christophe

2013-09-01

The use of carbon-based materials in electrochemical double-layer supercapacitors (EDLC) is currently being the focus of much research. Even though activated carbon (AC) is the state of the art electrode material, AC suffers from some drawbacks including its limited electrical conductivity, the need for a binder to ensure the expected electrode cohesion and its limited accessibility of its pores to solvated ions of the electrolyte. Owing to their unique physical properties, carbon nanotubes (CNTs) or graphene could overcome these drawbacks. It has been demonstrated that high specific capacitance could be obtained when the carbon accessible surface area of the electrode was finely tailored by using graphene combined with other carbonaceous nanoparticles such as CNTs12.In this work, to further increase the specific capacitance of the electrode, we have covalently grafted onto the surface of single-walled carbon nanotubes (SWCNTs), exfoliated graphite or graphene oxide (GO), anthraquinone (AQ) derivatives which are electrochemically active materials. The modified SWCNTs and graphene-like materials have been characterized by Raman spectroscopy, X-ray photoemission and cyclic voltammetry . Then suspensions based on mixtures of modified SWCNTs and modified graphene-like materials have been prepared and transformed into electrodes either by spray coating or by filtration. These electrodes have been characterized by SEM and by cyclic voltammetry in 0.1M H2S04 electrolyte.

Effects of proton irradiation on structural and electrochemical charge storage properties of TiO 2 nanotube electrodes for lithium-ion batteries

DOE PAGES

Smith, Kassiopeia A.; Savva, Andreas I.; Deng, Changjian; ...

2017-03-23

The effects of proton irradiation on nanostructured metal oxides have been investigated. Recent studies suggest that the presence of structural defects (e.g. vacancies and interstitials) in metal oxides may enhance the material's electrochemical charge storage capacity. A new approach to introduce defects in electrode materials is to use ion irradiation as it can produce a supersaturation of point defects in the target material. In this work we report the effect of low-energy proton irradiation on amorphous TiO 2 nanotube electrodes at both room temperature and high temperature (250 °C). Upon room temperature irradiation the nanotubes demonstrate an irradiation-induced phase transformationmore » to a mixture of amorphous, anatase, and rutile domains while showing a 35% reduction in capacity compared to anatase TiO 2. On the other hand, the high temperature proton irradiation induced a disordered rutile phase within the nanotubes as characterized by Raman spectroscopy and transmission electron microscopy, which displays an improved capacity by 20% at ~240 mA h g –1 as well as improved rate capability compared to an unirradiated anatase sample. Voltammetric sweep data were used to determine the contributions from diffusion-limited intercalation and capacitive processes and it was found that the electrodes after irradiation had more contributions from diffusion in lithium charge storage. Finally, our work suggests that tailoring the defect generation through ion irradiation within metal oxide electrodes could present a new avenue for designing advanced electrode materials.« less

Effects of proton irradiation on structural and electrochemical charge storage properties of TiO 2 nanotube electrodes for lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Kassiopeia A.; Savva, Andreas I.; Deng, Changjian

The effects of proton irradiation on nanostructured metal oxides have been investigated. Recent studies suggest that the presence of structural defects (e.g. vacancies and interstitials) in metal oxides may enhance the material's electrochemical charge storage capacity. A new approach to introduce defects in electrode materials is to use ion irradiation as it can produce a supersaturation of point defects in the target material. In this work we report the effect of low-energy proton irradiation on amorphous TiO 2 nanotube electrodes at both room temperature and high temperature (250 °C). Upon room temperature irradiation the nanotubes demonstrate an irradiation-induced phase transformationmore » to a mixture of amorphous, anatase, and rutile domains while showing a 35% reduction in capacity compared to anatase TiO 2. On the other hand, the high temperature proton irradiation induced a disordered rutile phase within the nanotubes as characterized by Raman spectroscopy and transmission electron microscopy, which displays an improved capacity by 20% at ~240 mA h g –1 as well as improved rate capability compared to an unirradiated anatase sample. Voltammetric sweep data were used to determine the contributions from diffusion-limited intercalation and capacitive processes and it was found that the electrodes after irradiation had more contributions from diffusion in lithium charge storage. Finally, our work suggests that tailoring the defect generation through ion irradiation within metal oxide electrodes could present a new avenue for designing advanced electrode materials.« less

Lignin as a Binder Material for Eco-Friendly Li-Ion Batteries

PubMed Central

Lu, Huiran; Cornell, Ann; Alvarado, Fernando; Behm, Mårten; Leijonmarck, Simon; Li, Jiebing; Tomani, Per; Lindbergh, Göran

2016-01-01

The industrial lignin used here is a byproduct from Kraft pulp mills, extracted from black liquor. Since lignin is inexpensive, abundant and renewable, its utilization has attracted more and more attention. In this work, lignin was used for the first time as binder material for LiFePO4 positive and graphite negative electrodes in Li-ion batteries. A procedure for pretreatment of lignin, where low-molecular fractions were removed by leaching, was necessary to obtain good battery performance. The lignin was analyzed for molecular mass distribution and thermal behavior prior to and after the pretreatment. Electrodes containing active material, conductive particles and lignin were cast on metal foils, acting as current collectors and characterized using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge cycles. Good reversible capacities were obtained, 148 mAh·g−1 for the positive electrode and 305 mAh·g−1 for the negative electrode. Fairly good rate capabilities were found for both the positive electrode with 117 mAh·g−1 and the negative electrode with 160 mAh·g−1 at 1C. Low ohmic resistance also indicated good binder functionality. The results show that lignin is a promising candidate as binder material for electrodes in eco-friendly Li-ion batteries. PMID:28773252

Integration of Microchip Electrophoresis with Electrochemical Detection Using an Epoxy-Based Molding Method to Embed Multiple Electrode Materials

PubMed Central

Johnson, Alicia S.; Selimovic, Asmira; Martin, R. Scott

2012-01-01

This paper describes the use of epoxy-encapsulated electrodes to integrate microchip-based electrophoresis with electrochemical detection. Devices with various electrode combinations can easily be developed. This includes a palladium decoupler with a downstream working electrode material of either gold, mercury/gold, platinum, glassy carbon, or a carbon fiber bundle. Additional device components such as the platinum wires for the electrophoresis separation and the counter electrode for detection can also be integrated into the epoxy base. The effect of the decoupler configuration was studied in terms of the separation performance, detector noise, and the ability to analyze samples of a high ionic strength. The ability of both glassy carbon and carbon fiber bundle electrodes to analyze a complex mixture was demonstrated. It was also shown that a PDMS-based valving microchip can be used along with the epoxy embedded electrodes to integrate microdialysis sampling with microchip electrophoresis and electrochemical detection, with the microdialysis tubing also being embedded in the epoxy substrate. This approach enables one to vary the detection electrode material as desired in a manner where the electrodes can be polished and modified in a similar fashion to electrochemical flow cells used in liquid chromatography. PMID:22038707

Battery Electrode Materials with High Cycle Lifetimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prof. Brent Fultz

2001-06-29

In an effort to understand the capacity fade of nickel-metal hydride (Ni-MH) batteries, we performed a systematic study of the effects of solute additions on the cycle life of metal hydride electrodes. We also performed a series of measurements on hydrogen absorption capacities of novel carbon and graphite-based materials including graphite nanofibers and single-walled carbon nanotubes. Towards the end of this project we turned our attention to work on Li-ion cells with a focus on anode materials.

Advances in lightweight nickel electrode technology

NASA Technical Reports Server (NTRS)

Coates, Dwaine; Paul, Gary; Daugherty, Paul

1989-01-01

Studies are currently underway to further the development of lightweight nickel electrode technology. Work is focused primarily on the space nickel-hydrogen system and nickel-iron system but is also applicable to the nickel-cadmium and nickel-zinc systems. The goal is to reduce electrode weight while maintaining or improving performance, thereby increasing electrode energy density. Two basic electrode structures are being investigated. The first is the traditional nickel sponge produced from sintered nickel-carbonyl powder. The second is a new material for this application which consists of a non-woven mat of nickel fiber. Electrodes are being manufactured, tested, and evaluated at the electrode and cell level.

Advances in lightweight nickel electrode technology

NASA Technical Reports Server (NTRS)

Coates, Dwaine; Paul, Gary; Wheeler, James R.; Daugherty, Paul

1989-01-01

Studies are currently underway to further the development of lightweight nickel electrode technology. Work is focused primarily on the space nickel-hydrogen system and nickel-iron system but is also applicable to the nickel-cadmium and nickel-zinc systems. The goal is to reduce electrode weight while maintaining or improving performance thereby increasing electrode energy density. Two basic electrode structures are being investigated. The first is the traditional nickel sponge produced from sintered nickel-carbonyl powder and the second is a new material for this application which consists of a non-woven mat of nickel fiber. Electrodes are being manufactured, tested and evaluated at the electrode and cell level.

Determination of platinum in mineral raw materials by switching chronoamperometry

NASA Astrophysics Data System (ADS)

Pakrieva, E.; Oskina, Y.; Ustinova, E.

2014-08-01

The technique of platinum (IV) determination in mineral raw materials with the application of switching chronoamperometry has been offered. The graphite electrode impregnated with polyethylene was used as the working electrode. The hydrolytic precipitation method with 3% NaOH solution has been developed to separate platinum from the sample matrix. The use of switching chronoamperometry applied to the assessment of the platinum content in geological objects has been demonstrated.

Spectro-Electrochemical Examination of the Formation of Dimethyl Carbonate from CO and Methanol at Different Electrode Materials

PubMed Central

2017-01-01

In this work, we report a fundamental mechanistic study of the electrochemical oxidative carbonylation of methanol with CO for the synthesis of dimethyl carbonate on metallic electrodes at low overpotentials. For the first time, the reaction was shown to take place on the metallic catalysts without need of oxidized metals or additives. Moreover, in-situ spectroelectrochemical techniques were applied to this electrosynthesis reaction in order to reveal the reaction intermediates and to shed light into the reaction mechanism. Fourier transformed infrared spectroscopy was used with different electrode materials (Au, Pd, Pt, and Ag) to assess the effect of the electrode material on the reaction and the dependence of products and intermediates on the applied potentials. It was observed that the dimethyl carbonate is only formed when the electrode is able to decompose/oxidize MeOH to form (adsorbed) methoxy groups that can further react with CO to dimethyl carbonate. Furthermore, the electrode needs to adsorb CO not too strongly; otherwise, further reaction will be inhibited because of surface poisoning by CO. PMID:28929754

The cell-in-series method: A technique for accelerated electrode degradation in redox flow batteries

DOE PAGES

Pezeshki, Alan M.; Sacci, Robert L.; Veith, Gabriel M.; ...

2015-11-21

Here, we demonstrate a novel method to accelerate electrode degradation in redox flow batteries and apply this method to the all-vanadium chemistry. Electrode performance degradation occurred seven times faster than in a typical cycling experiment, enabling rapid evaluation of materials. This method also enables the steady-state study of electrodes. In this manner, it is possible to delineate whether specific operating conditions induce performance degradation; we found that both aggressively charging and discharging result in performance loss. Post-mortem x-ray photoelectron spectroscopy of the degraded electrodes was used to resolve the effects of state of charge (SoC) and current on the electrodemore » surface chemistry. For the electrode material tested in this work, we found evidence that a loss of oxygen content on the negative electrode cannot explain decreased cell performance. Furthermore, the effects of decreased electrode and membrane performance on capacity fade in a typical cycling battery were decoupled from crossover; electrode and membrane performance decay were responsible for a 22% fade in capacity, while crossover caused a 12% fade.« less

A difference in using atomic layer deposition or physical vapour deposition TiN as electrode material in metal-insulator-metal and metal-insulator-silicon capacitors.

PubMed

Groenland, A W; Wolters, R A M; Kovalgin, A Y; Schmitz, J

2011-09-01

In this work, metal-insulator-metal (MIM) and metal-insulator-silicon (MIS) capacitors are studied using titanium nitride (TiN) as the electrode material. The effect of structural defects on the electrical properties on MIS and MIM capacitors is studied for various electrode configurations. In the MIM capacitors the bottom electrode is a patterned 100 nm TiN layer (called BE type 1), deposited via sputtering, while MIS capacitors have a flat bottom electrode (called BE type 2-silicon substrate). A high quality 50-100 nm thick SiO2 layer, made by inductively-coupled plasma CVD at 150 degrees C, is deposited as a dielectric on top of both types of bottom electrodes. BE type 1 (MIM) capacitors have a varying from low to high concentration of structural defects in the SiO2 layer. BE type 2 (MIS) capacitors have a low concentration of structural defects and are used as a reference. Two sets of each capacitor design are fabricated with the TiN top electrode deposited either via physical vapour deposition (PVD, i.e., sputtering) or atomic layer deposition (ALD). The MIM and MIS capacitors are electrically characterized in terms of the leakage current at an electric field of 0.1 MV/cm (I leak) and for different structural defect concentrations. It is shown that the structural defects only show up in the electrical characteristics of BE type 1 capacitors with an ALD TiN-based top electrode. This is due to the excellent step coverage of the ALD process. This work clearly demonstrates the sensitivity to process-induced structural defects, when ALD is used as a step in process integration of conductors on insulation materials.

High performance symmetric supercapacitor based on zinc hydroxychloride nanosheets and 3D graphene-nickel foam composite

NASA Astrophysics Data System (ADS)

Khamlich, S.; Abdullaeva, Z.; Kennedy, J. V.; Maaza, M.

2017-05-01

In this work, zinc hydroxychloride nanosheets (ZHCNs) were deposited on 3d graphene-nickel foam (NiF-G) by employing a simple hydrothermal synthesis method to form NiF-G/ZHCNs composite electrode materials. The fabricated NiF-G/ZHCNs electrode revealed a well-developed pore structures with high specific surface area of 119 m2 g-1, and used as electrode materials for symmetric supercapacitor with aqueous alkaline electrolyte. The specific areal capacitance and electron charge transfer resistance (Rct) were 222 mF cm-2 (at current density of 1.0 mA cm-2) and 1.63 Ω, respectively, in a symmetric two-electrode system. After 5000 cycles with galvanostatic charge/discharge, the device can maintain 96% of its initial capacitance under 1.0 mA cm-2 and showed low Rct of about 9.84 Ω. These results indicate that NiF-G/ZHCNs composite is an excellent electrode material for electrochemical energy storage devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobb, Corie L.; Solberg, Scott E.

3-dimensional (3D) electrode architectures have been explored as a means to decouple power and energy trade-offs in thick battery electrodes. Limited work has been published which systematically examines the impact of these architectures at the pouch cell level. This paper conducts an analysis on the potential capacity gains that can be realized with thick co-extruded electrodes in a pouch cell. Moreover, our findings show that despite lower active material composition for each cathode layer, the effective gain in thickness and active material loading enables pouch cell capacity gains greater than 10% with a Lithium Nickel Manganese Cobalt Oxide (NMC) materialsmore » system.« less

CTAB-Aided Synthesis of Stacked V2O5 Nanosheets: Morphology, Electrochemical Features and Asymmetric Device Performance

NASA Astrophysics Data System (ADS)

Saravanakumar, B.; Maruthamuthu, S.; Umadevi, V.; Saravanan, V.

To accomplish superior performance in supercapacitors, a fresh class of electrode materials with advantageous structures is essential. Owing to its rich electrochemical activity, vanadium oxides are considered to be an attractive electrode material for energy storing devices. In this work, vanadium pentoxide (V2O5) nanostructures were prepared using surfactant (CTAB)-assisted hydrothermal route. Stacked V2O5 sheets enable additional channels for electrolyte ion intercalation. These stacked V2O5 nanosheets show highest specific capacitance of 466Fg-1 at 0.5Ag-1. In addition, it exhibits good rate capacity, lower value of charge transfer resistance and good stability when used as an electrode material for supercapacitors. Further, an asymmetric supercapacitor device was assembled utilizing the stacked V2O5 sheets and activated carbon as electrodes. The electrochemical features of the device are also discussed.

Stress and Strain in Silicon Electrode Models

DOE PAGES

Higa, Kenneth; Srinivasan, Venkat

2015-03-24

While the high capacity of silicon makes it an attractive negative electrode for Li-ion batteries, the associated large volume change results in fracture and capacity fade. Composite electrodes incorporating silicon have additional complexity, as active material is attached to surrounding material which must likewise experience significant volume change. In this paper, a finite-deformation model is used to explore, for the first time, mechanical interactions between a silicon particle undergoing lithium insertion, and attached binder material. Simulations employ an axisymmetric model system in which solutions vary in two spatial directions and shear stresses develop at interfaces between materials. The mechanical responsemore » of the amorphous active material is dependent on lithium concentration, and an equation of state incorporating reported volume expansion data is used. Simulations explore the influence of active material size and binder stiffness, and suggest delamination as an additional mode of material damage. Computed strain energies and von Mises equivalent stresses are in physically-relevant ranges, comparable to reported yield stresses and adhesion energies, and predicted trends are largely consistent with reported experimental results. It is hoped that insights from this work will support the design of more robust silicon composite electrodes.« less

Fabrication and testing of an electrochemical microcell for in situ soft X-ray microspectroscopy measurements

NASA Astrophysics Data System (ADS)

Gianoncelli, A.; Kaulich, B.; Kiskinova, M.; Mele, C.; Prasciolu, M.; Sgura, I.; Bozzini, B.

2013-03-01

In this paper we report on the fabrication and testing of a novel concept of electrochemical microcell for in-situ soft X-ray microspectroscopy in transmission. The microcell, fabricated by electron-beam lithography, implements an improved electrode design, with optimal current density distribution and minimised ohmic drop, allowing the same three-electrode electrochemical control achievable with traditional cells. Moreover standard electroanalytical measurements, such as cyclic voltammetry, can be routinely performed. As far as the electrolyte is concerned, we selected a room-temperature ionic-liquid. Some of the materials belonging to this class, in addition to a broad range of outstanding electrochemical properties, feature two highlights that are crucial for in situ, soft X-ray transmission work: spinnability, enabling accurate thickness control, and stability to UHV, allowing operation of an open cell in the analysis chamber vacuum (10-6 mbar). The cell can, of course, be used also with non-vacuum stable electrolytes in the sealed version developed in previous work in our group. In this study, the microcell designed, fabricated and tested in situ by applying an anodic polarisation to a Au electrode and following the formation of a distribution of corrosion features. This specific material combination presented in this work does not limit the cell concept, that can implement any electrodic material grown by lithography, any liquid electrolyte and any spinnable solid electrolyte.

Influence of carbon electrode material on energy recovery from winery wastewater using a dual-chamber microbial fuel cell.

PubMed

Penteado, Eduardo D; Fernandez-Marchante, Carmen M; Zaiat, Marcelo; Gonzalez, Ernesto R; Rodrigo, Manuel A

2017-06-01

The aim of this work was to evaluate three carbon materials as anodes in microbial fuel cells (MFCs), clarifying their influence on the generation of electricity and on the treatability of winery wastewater, a highly organic-loaded waste. The electrode materials tested were carbon felt, carbon cloth and carbon paper and they were used at the same time as anode and cathode in the tests. The MFC equipped with carbon felt reached the highest voltage and power (72 mV and 420 mW m -2 , respectively), while the lowest values were observed when carbon paper was used as electrode (0.2 mV and 8.37·10 -6  mW m -2 , respectively). Chemical oxygen demand (COD) removal from the wastewater was observed to depend on the electrode material, as well. When carbon felt was used, the MFC showed the highest average organic matter consumption rate (650 mg COD L -1  d -1 ), whereas by using carbon paper the rate decreased to 270 mg COD L -1  d -1 . Therefore, both electricity generation and organic matter removal are strongly related not to the chemical composition of the electrode (which was graphite carbon in the three electrodes), but to its surface features and, consequently, to the amount of biomass adhered to the electrode surface.

Sulphured Polyacrylonitrile Composite Analysed by in operando UV-Visible Spectroscopy and 4-electrode Swagelok Cell.

PubMed

Dominko, Robert; Patel, Manu U M; Bele, Marjan; Pejovnik, Stane

2016-01-01

The electrochemical characteristics of sulfurized polyacrylonitrile composite (PAN/S) cathodes were compared with the commonly used carbon/S-based composite material. The difference in the working mechanism of these composites was examined. Analytical investigations were performed on both kinds of cathode electrode composites by using two reliable analytical techniques, in-situ UV-Visible spectroscopy and a four-electrode Swagelok cell. This study differentiates the working mechanisms of PAN/S composites from conventional elemental sulphur/carbon composite and also sheds light on factors that could be responsible for capacity fading in the case of PAN/S composites.

Doped polymer semiconductors with ultrahigh and ultralow work functions for ohmic contacts.

PubMed

Tang, Cindy G; Ang, Mervin C Y; Choo, Kim-Kian; Keerthi, Venu; Tan, Jun-Kai; Syafiqah, Mazlan Nur; Kugler, Thomas; Burroughes, Jeremy H; Png, Rui-Qi; Chua, Lay-Lay; Ho, Peter K H

2016-11-24

To make high-performance semiconductor devices, a good ohmic contact between the electrode and the semiconductor layer is required to inject the maximum current density across the contact. Achieving ohmic contacts requires electrodes with high and low work functions to inject holes and electrons respectively, where the work function is the minimum energy required to remove an electron from the Fermi level of the electrode to the vacuum level. However, it is challenging to produce electrically conducting films with sufficiently high or low work functions, especially for solution-processed semiconductor devices. Hole-doped polymer organic semiconductors are available in a limited work-function range, but hole-doped materials with ultrahigh work functions and, especially, electron-doped materials with low to ultralow work functions are not yet available. The key challenges are stabilizing the thin films against de-doping and suppressing dopant migration. Here we report a general strategy to overcome these limitations and achieve solution-processed doped films over a wide range of work functions (3.0-5.8 electronvolts), by charge-doping of conjugated polyelectrolytes and then internal ion-exchange to give self-compensated heavily doped polymers. Mobile carriers on the polymer backbone in these materials are compensated by covalently bonded counter-ions. Although our self-compensated doped polymers superficially resemble self-doped polymers, they are generated by separate charge-carrier doping and compensation steps, which enables the use of strong dopants to access extreme work functions. We demonstrate solution-processed ohmic contacts for high-performance organic light-emitting diodes, solar cells, photodiodes and transistors, including ohmic injection of both carrier types into polyfluorene-the benchmark wide-bandgap blue-light-emitting polymer organic semiconductor. We also show that metal electrodes can be transformed into highly efficient hole- and electron-injection contacts via the self-assembly of these doped polyelectrolytes. This consequently allows ambipolar field-effect transistors to be transformed into high-performance p- and n-channel transistors. Our strategy provides a method for producing ohmic contacts not only for organic semiconductors, but potentially for other advanced semiconductors as well, including perovskites, quantum dots, nanotubes and two-dimensional materials.

Effective recycling of manganese oxide cathodes for lithium based batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poyraz, Altug S.; Huang, Jianping; Cheng, Shaobo

Rechargeable lithium ion batteries (LIBs) occupy a prominent consumer presence due to their high cell potential and gravimetric energy density, there are also limited opportunities for electrode recycling. Currently used or proposed cathode recycling processes are multistep procedures which involve sequences of mechanical, thermal, and chemical leaching, where only the base material is recovered and significant processing is required to generate a recycled electrode structure. Another significant issue facing lithium based batteries is capacity fade due to structural degradation of the electroactive material upon extending cycling. Herein, inspired by heterogeneous catalyst thermal regeneration strategies, we present a new facile cathodemore » recycling process, where previously used cathodes are removed from a cell, heat treated, and then inserted into a new cell restoring the delivered capacity and cycle life. An environmentally sustainable manganese based material is employed, where binder-free self-supporting (BFSS) electrodes are prepared using a fibrous, high aspect ratio manganese oxide active material. After 200 discharge–charge cycles, the recycled BFSS electrodes display restored crystallinity and oxidation state of the manganese centers with the resulting electrochemistry (capacity and coulombic efficiency) reminiscent of freshly prepared BFSS cathodes. Of note, the BFSS electrode structure is robust with no degradation during the cell disassembly, electrode recovery, washing, and heat treatment steps; thus no post-processing is required for the recycled electrode. Furthermore, this work shows for the first time that a thermal regeneration method previously employed in catalyst systems can fully restore battery electrochemical performance, demonstrating a novel electrode recycling process which could open up new possibilities for energy storage devices with extended electrode lifecycles.« less

Effective recycling of manganese oxide cathodes for lithium based batteries

DOE PAGES

Poyraz, Altug S.; Huang, Jianping; Cheng, Shaobo; ...

2016-02-29

Rechargeable lithium ion batteries (LIBs) occupy a prominent consumer presence due to their high cell potential and gravimetric energy density, there are also limited opportunities for electrode recycling. Currently used or proposed cathode recycling processes are multistep procedures which involve sequences of mechanical, thermal, and chemical leaching, where only the base material is recovered and significant processing is required to generate a recycled electrode structure. Another significant issue facing lithium based batteries is capacity fade due to structural degradation of the electroactive material upon extending cycling. Herein, inspired by heterogeneous catalyst thermal regeneration strategies, we present a new facile cathodemore » recycling process, where previously used cathodes are removed from a cell, heat treated, and then inserted into a new cell restoring the delivered capacity and cycle life. An environmentally sustainable manganese based material is employed, where binder-free self-supporting (BFSS) electrodes are prepared using a fibrous, high aspect ratio manganese oxide active material. After 200 discharge–charge cycles, the recycled BFSS electrodes display restored crystallinity and oxidation state of the manganese centers with the resulting electrochemistry (capacity and coulombic efficiency) reminiscent of freshly prepared BFSS cathodes. Of note, the BFSS electrode structure is robust with no degradation during the cell disassembly, electrode recovery, washing, and heat treatment steps; thus no post-processing is required for the recycled electrode. Furthermore, this work shows for the first time that a thermal regeneration method previously employed in catalyst systems can fully restore battery electrochemical performance, demonstrating a novel electrode recycling process which could open up new possibilities for energy storage devices with extended electrode lifecycles.« less

Material for electrodes of low temperature plasma generators

DOEpatents

Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich

2008-12-09

Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron: 3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, and municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

Material for electrodes of low temperature plasma generators

DOEpatents

Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich; Shiryaev, Vasili Nikolaevich

2010-03-02

Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron:3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

Pencil Graphite Electrodes: A Versatile Tool in Electroanalysis

PubMed Central

2017-01-01

Due to their electrochemical and economical characteristics, pencil graphite electrodes (PGEs) gained in recent years a large applicability to the analysis of various types of inorganic and organic compounds from very different matrices. The electrode material of this type of working electrodes is constituted by the well-known and easy commercially available graphite pencil leads. Thus, PGEs are cheap and user-friendly and can be employed as disposable electrodes avoiding the time-consuming step of solid electrodes surface cleaning between measurements. When compared to other working electrodes PGEs present lower background currents, higher sensitivity, good reproducibility, and an adjustable electroactive surface area, permitting the analysis of low concentrations and small sample volumes without any deposition/preconcentration step. Therefore, this paper presents a detailed overview of the PGEs characteristics, designs and applications of bare, and electrochemically pretreated and chemically modified PGEs along with the corresponding performance characteristics like linear range and detection limit. Techniques used for bare or modified PGEs surface characterization are also reviewed. PMID:28255500

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Fang; Yao, Yuze; Wang, Haiyan

Rational and precise control of the structure and dimension of electrode materials is an efficient way to improve their electrochemical performance. In this work, solvothermal or co-precipitation method is used to synthesize lithium-rich layered oxide materials of Li1.2Mn0.56Co0.12Ni0.12O2 (LLO) with various morphologies and structures, including microspheres, microrods, nanoplates, and irregular nanoparticles. These materials exhibit strong structure- dependent electrochemical properties. The porous hierarchical structured LLO microrods exhibit the best performance, delivering a discharge capacity of 264.6 mAh g(-1) at 0.5 C with over 91% retention after 100 cycles. At a high rate of 5 C, a high discharge capacity of 173.6more » mAh g(-1) can be achieved. This work reveals the relationship between the morphologies and electrochemical properties of LLO cathode materials, and provides a feasible approach to fabricating robust and high-performance electrode materials for lithium-ion batteries.« less

Review—Multifunctional Materials for Enhanced Li-Ion Batteries Durability: A Brief Review of Practical Options

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Anjan; Shilina, Yuliya; Ziv, Baruch

Transition metal (TM) ions dissolution from positive electrodes, migration to and deposition on negative electrodes, followed by Mn-catalyzed reactions of solvents and anions, with loss of Li+ ions, is a major degradation (DMDCR) mechanism in Li-ion batteries (LIBs) with spinel positive electrode materials. While the details of the DMDCR mechanism are still under debate, it is clear that HF and other acid species’ attack is the main cause in solutions with LiPF6 electrolyte. We first review the work on various mitigation measures for the DMDCR mechanism, now spanning more than two decades. We then discuss recent progress on our understandingmore » of Mn species in electrolyte solutions and the extension of a mitigation measure first proposed by Tarascon and coworkers in 1999, namely chelation of TM cations, to Mn cation trapping, HF scavenging, and alkali metal ions dispensing multi-functional materials. We focus on practicable, drop-in technical solutions, based on placing such materials in the inter-electrode space, with significant benefits for LIBs performance: increased capacity retention during operation at room and above-ambient temperatures as well as robust (both maximally ionically conducting and electronically insulating) solid-electrolyte interfaces, having reduced charge transfer and film resistances at both negative and positive electrodes. We illustrate the multifunctional materials approach with both new and previously published data. We also discuss and offer our evaluation regarding the merits and drawbacks of the various mitigation measures, with an eye for practically relevant technical solutions capable to meet both the performance requirements and cost constraints for commercial LIBs, and end with recommendations for future work.« less

Synthesis of a highly efficient 3D graphene-CNT-MnO2-PANI nanocomposite as a binder free electrode material for supercapacitors.

PubMed

Asif, Muhammad; Tan, Yi; Pan, Lujun; Rashad, Muhammad; Li, Jiayan; Fu, Xin; Cui, Ruixue

2016-09-29

Graphene based nanocomposites have been investigated intensively, as electrode materials for energy storage applications. In the current work, a graphene-CNT-MnO 2 -PANI (GCM@PANI) nanocomposite has been synthesized on 3D graphene grown on nickel foam, as a highly efficient binder free electrode material for supercapacitors. Interestingly, the specific capacitance of the synthesized electrode increases up to the first 1500 charge-discharge cycles, and is thus referred to as an electrode activation process. The activated GCM@PANI nanocomposite electrode exhibits an extraordinary galvanostatic specific capacitance of 3037 F g -1 at a current density of 8 A g -1 . The synthesized nanocomposite exhibits an excellent cyclic stability with a capacitance retention of 83% over 12 000 charge-discharge cycles, and a high rate capability by retaining a specific capacitance of 84.6% at a current density of 20 A g -1 . The structural and electrochemical analysis of the synthesized nanocomposite suggests that the astonishing electrochemical performance might be attributed to the growth of a novel PANI nanoparticle layer and the synergistic effect of CNT/MnO 2 nanostructures.

Vertically aligned single-walled carbon nanotubes as low-cost and high electrocatalytic counter electrode for dye-sensitized solar cells.

PubMed

Dong, Pei; Pint, Cary L; Hainey, Mel; Mirri, Francesca; Zhan, Yongjie; Zhang, Jing; Pasquali, Matteo; Hauge, Robert H; Verduzco, Rafael; Jiang, Mian; Lin, Hong; Lou, Jun

2011-08-01

A novel dye-sensitized solar cell (DSSC) structure using vertically aligned single-walled carbon nanotubes (VASWCNTs) as the counter electrode has been developed. In this design, the VASWCNTs serve as a stable high surface area and highly active electrocatalytic counter-electrode that could be a promising alternative to the conventional Pt analogue. Utilizing a scalable dry transfer approach to form a VASWCNTs conductive electrode, the DSSCs with various lengths of VASWCNTs were studied. VASWCNTs-DSSC with 34 μm original length was found to be the optimal choice in the present study. The highest conversion efficiencies of VASWCNTs-DSSC achieved 5.5%, which rivals that of the reference Pt DSSC. From the electrochemical impedance spectroscopy analysis, it shows that the new DSSC offers lower interface resistance between the electrolyte and the counter electrode. This reproducible work emphasizes the promise of VASWCNTs as efficient and stable counter electrode materials in DSSC device design, especially taking into account the low-cost merit of this promising material.

Facial synthesis of nanostructured ZnCo2O4 on carbon cloth for supercapacitor application

NASA Astrophysics Data System (ADS)

Patil, Swati J.; Park, Jungsung; Lee, Dong-Weon

2017-12-01

In this work, we have synthesized the ZnCo2O4 electrode by a facial one-step hydrothermal method on a carbon cloth for the supercapacitor application. The structural and phase purity of the prepared electrode material was confirmed by X-ray diffraction (XRD) technique. The surface morphology and elemental stoichiometry were studied using field emission scanning electron microscopy (FE-SEM). The FE-SEM micrograph illustrates that the ZnCo2O4 material is composed of microstrips with a ~0.5 μm width and length in micron uniformly covered the carbon cloth surface. The ZnCo2O4 electrode material further investigated for electrochemical analyses. The cyclic voltammetry results showed that the ZnCo2O4 microstrips electrode exhibited the highest specific capacitance of 1084 F/g at 2 mV/s scan rate. Remarkably, a maximum energy density of 12.5 Wh/kg was attained at a current density of 2 mA/cm2 with the power density of 3.6 kW/kg for the ZnCo2O4 microstrips electrode. Furthermore, the 96.2 % capacitive retention is obtained at a higher scan rate of 100 mV/s after 1000 CV cycles, indicating excellent cycling stability of the ZnCo2O4 microstrips electrode. The frequency-dependent rate capability and an ideal capacitive behaviour of the ZnCo2O4 microstrips electrode were analyzed using impedance analyses; a representing the ion diffusion structure of the material. These results show that the ZnCo2O4 microstrips electrode could be a promising material for supercapacitor application.

Characteristics of Sputtered Cr Thin Films and Application as a Working Electrode in Transparent Conductive Oxide-Less Dye-Sensitized Solar Cells.

PubMed

Park, Yong Seob; Kang, Ki-Noh; Kim, Young-Baek; Hwang, Sung Hwan; Lee, Jaehyeong

2018-09-01

Cr metal electrode was suggested as the working electrode material to fabricate DSSCs without the TCO, and thin films were fabricated by an unbalanced magnetron sputtering system. The surface morphologies show uniform and smooth surfaces regardless of various film thicknesses, and the small crystallites of various sizes were showed with the vertical direction on the surface of Cr thin films with the increase of film thickness. And also, the root mean square (RMS) surface roughness value of Cr thin films increased, and the sheet resistance is decreased with the increase of film thickness. The maximum cell efficiency of the TCO-less DSSC was observed when a Cr working electrode with a thickness of 80 nm was applied to the TCO-less DSSC. Consequently, these results are related to the result of the optimization of conduction characteristics, transmission properties and surface properties of Cr thin films.

Understanding Fundamentals and Reaction Mechanisms of Electrode Materials for Na-Ion Batteries.

PubMed

Yu, Linghui; Wang, Luyuan Paul; Liao, Hanbin; Wang, Jingxian; Feng, Zhenxing; Lev, Ovadia; Loo, Joachim S C; Sougrati, Moulay Tahar; Xu, Zhichuan J

2018-04-01

Development of efficient, affordable, and sustainable energy storage technologies has become an area of interest due to the worsening environmental issues and rising technological dependence on Li-ion batteries. Na-ion batteries (NIBs) have been receiving intensive research efforts during the last few years. Owing to their potentially low cost and relatively high energy density, NIBs are promising energy storage devices, especially for stationary applications. A fundamental understanding of electrode properties during electrochemical reactions is important for the development of low cost, high-energy density, and long shelf life NIBs. This Review aims to summarize and discuss reaction mechanisms of the major types of NIB electrode materials reported. By appreciating how the material works and the fundamental flaws it possesses, it is hoped that this Review will assist readers in coming up with innovative solutions for designing better materials for NIBs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Template-free synthesis of renewable macroporous carbon via yeast cells for high-performance supercapacitor electrode materials.

PubMed

Sun, Hongmei; He, Wenhui; Zong, Chenghua; Lu, Lehui

2013-03-01

The urgent need for sustainable development has forced material scientists to explore novel materials for next-generation energy storage devices through a green and facile strategy. In this context, yeast, which is a large group of single cell fungi widely distributed in nature environments, will be an ideal candidate for developing effective electrode materials with fascinating structures for high-performance supercapacitors. With this in mind, herein, we present the first example of creating three-dimensional (3D) interpenetrating macroporous carbon materials via a template-free method, using the green, renewable, and widespread yeast cells as the precursors. Remarkably, when the as-prepared materials are used as the electrode materials for supercapacitors, they exhibit outstanding performance with high specific capacitance of 330 F g(-1) at a current density of 1 A g(-1), and good stability, even after 1000 charge/discharge cycles. The approach developed in this work provides a new view of making full use of sustainable resources endowed by nature, opening the avenue to designing and producing robust materials with great promising applications in high-performance energy-storage devices.

Low-cost electrodes for stable perovskite solar cells

NASA Astrophysics Data System (ADS)

Bastos, João P.; Manghooli, Sara; Jaysankar, Manoj; Tait, Jeffrey G.; Qiu, Weiming; Gehlhaar, Robert; De Volder, Michael; Uytterhoeven, Griet; Poortmans, Jef; Paetzold, Ulrich W.

2017-06-01

Cost-effective production of perovskite solar cells on an industrial scale requires the utilization of exclusively inexpensive materials. However, to date, highly efficient and stable perovskite solar cells rely on expensive gold electrodes since other metal electrodes are known to cause degradation of the devices. Finding a low-cost electrode that can replace gold and ensure both efficiency and long-term stability is essential for the success of the perovskite-based solar cell technology. In this work, we systematically compare three types of electrode materials: multi-walled carbon nanotubes (MWCNTs), alternative metals (silver, aluminum, and copper), and transparent oxides [indium tin oxide (ITO)] in terms of efficiency, stability, and cost. We show that multi-walled carbon nanotubes are the only electrode that is both more cost-effective and stable than gold. Devices with multi-walled carbon nanotube electrodes present remarkable shelf-life stability, with no decrease in the efficiency even after 180 h of storage in 77% relative humidity (RH). Furthermore, we demonstrate the potential of devices with multi-walled carbon nanotube electrodes to achieve high efficiencies. These developments are an important step forward to mass produce perovskite photovoltaics in a commercially viable way.

Low work function materials for microminiature energy conversion and recovery applications

DOEpatents

Zavadil, Kevin R.; Ruffner, Judith A.; King, Donald B.

2003-05-13

Low work function materials are disclosed together with methods for their manufacture and integration with electrodes used in thermionic conversion applications (specifically microminiature thermionic conversion applications). The materials include a mixed oxide system and metal in a compositionally modulated structure comprised of localized discontinuous structures of material that are deposited using techniques suited to IC manufacture, such as rf sputtering or CVD. The structures, which can include layers are then heated to coalescence yielding a thin film that is both durable and capable of electron emission under thermionic conversion conditions used for microminiature thermionic converters. Using the principles of the invention, thin film electrodes (emitters and collectors) required for microconverter technology are manufactured using a single process deposition so as to allow for full fabrication integration consistent with batch processing, and tailoring of emission/collection properties. In the preferred embodiment, the individual layers include mixed BaSrCaO, scandium oxide and tungsten.

Application of polymer sensitive MRI sequence to localization of EEG electrodes.

PubMed

Butler, Russell; Gilbert, Guillaume; Descoteaux, Maxime; Bernier, Pierre-Michel; Whittingstall, Kevin

2017-02-15

The growing popularity of simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) opens up the possibility of imaging EEG electrodes while the subject is in the scanner. Such information could be useful for improving the fusion of EEG-fMRI datasets. Here, we report for the first time how an ultra-short echo time (UTE) MR sequence can image the materials of an MR-compatible EEG cap, finding that electrodes and some parts of the wiring are visible in a high resolution UTE. Using these images, we developed a segmentation procedure to obtain electrode coordinates based on voxel intensity from the raw UTE, using hand labeled coordinates as the starting point. We were able to visualize and segment 95% of EEG electrodes using a short (3.5min) UTE sequence. We provide scripts and template images so this approach can now be easily implemented to obtain precise, subject-specific EEG electrode positions while adding minimal acquisition time to the simultaneous EEG-fMRI protocol. T1 gel artifacts are not robust enough to localize all electrodes across subjects, the polymers composing Brainvision cap electrodes are not visible on a T1, and adding T1 visible materials to the EEG cap is not always possible. We therefore consider our method superior to existing methods for obtaining electrode positions in the scanner, as it is hardware free and should work on a wide range of materials (caps). EEG electrode positions are obtained with high precision and no additional hardware. Copyright © 2016 Elsevier B.V. All rights reserved.

Functional Carbon Materials for Electrochemical Energy Storage

NASA Astrophysics Data System (ADS)

Zhou, Huihui

The ability to harvest and convert solar energy has been associated with the evolution of human civilization. The increasing consumption of fossil fuels since the industrial revolution, however, has brought to concerns in ecological deterioration and depletion of the fossil fuels. Facing these challenges, humankind is forced to seek for clean, sustainable and renewable energy resources, such as biofuels, hydraulic power, wind power, geothermal energy and other kinds of alternative energies. However, most alternative energy sources, generally in the form of electrical energy, could not be made available on a continuous basis. It is, therefore, essential to store such energy into chemical energy, which are portable and various applications. In this context, electrochemical energy-storage devices hold great promises towards this goal. The most common electrochemical energy-storage devices are electrochemical capacitors (ECs, also called supercapacitors) and batteries. In comparison to batteries, ECs posses high power density, high efficiency, long cycling life and low cost. ECs commonly utilize carbon as both (symmetric) or one of the electrodes (asymmetric), of which their performance is generally limited by the capacitance of the carbon electrodes. Therefore, developing better carbon materials with high energy density has been emerging as one the most essential challenges in the field. The primary objective of this dissertation is to design and synthesize functional carbon materials with high energy density at both aqueous and organic electrolyte systems. The energy density (E) of ECs are governed by E = CV 2/2, where C is the total capacitance and V is the voltage of the devices. Carbon electrodes with high capacitance and high working voltage should lead to high energy density. In the first part of this thesis, a new class of nanoporous carbons were synthesized for symmetric supercapacitors using aqueous Li2SO4 as the electrolyte. A unique precursor was adopted to create uniformly distributed nanopores with large surface area, leading to high-performance electrodes with high capacitance, excellent rate performance and stable cycling, even under a high working voltage of 1.6V. The second part of this dissertation work further improved the capacitance of the carbon electrodes by fluorine doping. This doping process enhances the affinity of the carbon surface with organic electrolytes, leading to further improved capacitance and energy density. In the third part, carbon materials were synthesized with high surface area, capacitance and working voltage of 4V in organic electrolyte, leading to the construction of prototyped devices with energy density comparable to those of the current lead-acid batteries. Besides the abovementioned research, hierarchical graphitic carbons were also explored for lithium ion batteries and supercapacitors. Overall, through rational design of carbons with optimized pore configuration and surface chemistry, carbon electrodes with improved energy density and rate performance were improved significantly. Collectively, this thesis work systematically unveils simple yet effective strategies to achieve high performance carbon-based supercapacitors with high power density and high energy density, including the following aspects: 1) Constructed electrodes with high capacitance through building favorable ion/electron transportation pathways, tuning pore structure and pore size. 2) Improved the capacitance through enhancing the affinity between the carbon electrodes and electrolytes by doping the carbons with heteroatoms. 3) Explored and understand the roles of heteroatom doping in the capacitive behavior by both experimental measurement and computational modeling. 4) Improved energy density of carbon electrodes by enlarging their working voltage in aqueous and organic electrolyte. 5) Scalable and effective production of hierarchically porous graphite particles through aerosol process for use as the anode materials of lithium ion batteries. These strategies can be extended as a general design platform for other high-performance energy storage materials such as fuel cells and lithium-ion batteries.

Performance and Surface Integrity of Ti6Al4V After Sinking EDM with Special Graphite Electrodes

NASA Astrophysics Data System (ADS)

Amorim, Fred L.; Stedile, Leandro J.; Torres, Ricardo D.; Soares, Paulo C.; Henning Laurindo, Carlos A.

2014-04-01

Titanium and its alloys have high chemical reactivity with most of the cutting tools. This makes it difficult to work with these alloys using conventional machining processes. Electrical discharge machining (EDM) emerges as an alternative technique to machining these materials. In this work, it is investigated the performance of three special grades of graphite as electrodes when ED-Machining Ti6Al4V samples under three different regimes. The main influences of electrical parameters are discussed for the samples material removal rate, volumetric relative wear and surface roughness. The samples surfaces were evaluated using SEM images, microhardness measurements, and x-ray diffraction. It was found that the best results for samples material removal rate, surface roughness, and volumetric relative wear were obtained for the graphite electrode with 10-μm particle size and negative polarity. For all samples machined by EDM and characterized by x-ray (XRD), it was identified the presence of titanium carbides. For the finish EDM regimes, the recast layer presents an increased amount of titanium carbides compared to semi-finish and rough regimes.

Hierarchically structured materials for lithium batteries

NASA Astrophysics Data System (ADS)

Xiao, Jie; Zheng, Jianming; Li, Xiaolin; Shao, Yuyan; Zhang, Ji-Guang

2013-10-01

The lithium-ion battery (LIB) is one of the most promising power sources to be deployed in electric vehicles, including solely battery powered vehicles, plug-in hybrid electric vehicles, and hybrid electric vehicles. With the increasing demand for devices of high-energy densities (>500 Wh kg-1), new energy storage systems, such as lithium-oxygen (Li-O2) batteries and other emerging systems beyond the conventional LIB, have attracted worldwide interest for both transportation and grid energy storage applications in recent years. It is well known that the electrochemical performance of these energy storage systems depends not only on the composition of the materials, but also on the structure of the electrode materials used in the batteries. Although the desired performance characteristics of batteries often have conflicting requirements with the micro/nano-structure of electrodes, hierarchically designed electrodes can be tailored to satisfy these conflicting requirements. This work will review hierarchically structured materials that have been successfully used in LIB and Li-O2 batteries. Our goal is to elucidate (1) how to realize the full potential of energy materials through the manipulation of morphologies, and (2) how the hierarchical structure benefits the charge transport, promotes the interfacial properties and prolongs the electrode stability and battery lifetime.

Doping as a means to probe the potential dependence of dopamine adsorption on carbon-based surfaces: A first-principles study

NASA Astrophysics Data System (ADS)

Aarva, Anja; Laurila, Tomi; Caro, Miguel A.

2017-06-01

In this work, we study the adsorption characteristics of dopamine (DA), ascorbic acid (AA), and dopaminequinone (DAox) on carbonaceous electrodes. Our goal is to obtain a better understanding of the adsorption behavior of these analytes in order to promote the development of new carbon-based electrode materials for sensitive and selective detection of dopamine in vivo. Here we employ density functional theory-based simulations to reach a level of detail that cannot be achieved experimentally. To get a broader understanding of carbonaceous surfaces with different morphological characteristics, we compare three materials: graphene, diamond, and amorphous carbon (a-C). Effects of solvation on adsorption characteristics are taken into account via a continuum solvent model. Potential changes that take place during electrochemical measurements, such as cyclic voltammetry, can also alter the adsorption behavior. In this study, we have utilized doping as an indirect method to simulate these changes by shifting the work function of the electrode material. We demonstrate that sp2- and sp3-rich materials, as well as a-C, respond markedly different to doping. Also the adsorption behavior of the molecules studied here differs depending on the surface material and the change in the surface potential. In all cases, adsorption is spontaneous, but covalent bonding is not detected in vacuum. The aqueous medium has a large effect on the adsorption behavior of DAox, which reaches its highest adsorption energy on diamond when the potential is shifted to more negative values. In all cases, inclusion of the solvent enhances the charge transfer between the slab and DAox. Largest differences in adsorption energy between DA and AA are obtained on graphene. Gaining better understanding of the behavior of the different forms of carbon when used as electrode materials provides a means to rationalize the observed complex phenomena taking place at the electrodes during electrochemical oxidation/reduction of these biomolecules.

All 2D, high mobility, flexible, transparent thin film transistor

DOEpatents

Das, Saptarshi; Sumant, Anirudha V.; Roelofs, Andreas

2017-01-17

A two-dimensional thin film transistor and a method for manufacturing a two-dimensional thin film transistor includes layering a semiconducting channel material on a substrate, providing a first electrode material on top of the semiconducting channel material, patterning a source metal electrode and a drain metal electrode at opposite ends of the semiconducting channel material from the first electrode material, opening a window between the source metal electrode and the drain metal electrode, removing the first electrode material from the window located above the semiconducting channel material providing a gate dielectric above the semiconducting channel material, and providing a top gate above the gate dielectric, the top gate formed from a second electrode material. The semiconducting channel material is made of tungsten diselenide, the first electrode material and the second electrode material are made of graphene, and the gate dielectric is made of hexagonal boron nitride.

Communication—Analysis of Thick Co-Extruded Cathodes for Higher-Energy-and-Power Lithium-Ion Batteries

DOE PAGES

Cobb, Corie L.; Solberg, Scott E.

2017-04-29

3-dimensional (3D) electrode architectures have been explored as a means to decouple power and energy trade-offs in thick battery electrodes. Limited work has been published which systematically examines the impact of these architectures at the pouch cell level. This paper conducts an analysis on the potential capacity gains that can be realized with thick co-extruded electrodes in a pouch cell. Moreover, our findings show that despite lower active material composition for each cathode layer, the effective gain in thickness and active material loading enables pouch cell capacity gains greater than 10% with a Lithium Nickel Manganese Cobalt Oxide (NMC) materialsmore » system.« less

The research of structure and mechanical properties of superhard electro-spark coatings for hardwearing mining tools

NASA Astrophysics Data System (ADS)

Bajin, P. A.; Chijikov, A. P.; Leybo, D. V.; Chuprunov, K. O.; Yudin, A. G.; Alymov, M. A.; Kuznetsov, D. V.

2016-01-01

The development of low cost and hardwearing mining tools is one of the most important areas in mining industry. It is especially important for technologies of rare and rare earth metals mining due to high hardness of related ores. Coatings for electrodes, produced by extrusion of self-propagating high temperature synthesis (SHS) products from hard-alloyed materials with nanosized structure, for further application in processes of electrospark alloying and deposition were studied in this work. The results of microstructure and properties of deposited layers, interaction of support with SHS produced electrodes, comparison of frictional properties of obtained materials as well as some industrial testing results are presented in this work.

Work function determination of promising electrode materials for thermionic converters

NASA Technical Reports Server (NTRS)

Jacobson, D.

1977-01-01

Work performed on this contract was primarily for the evaluation of selected electrode materials for thermionic energy converters. The original objective was to characterize selected nickel based superalloys up to temperatures of 1400 K. It was found that an early selection, Inconel 800 produced a high vapor pressure which interfered with the vacuum emission measurements. The program then shifted to two other areas. The first area was to obtain emission from the superalloys in a cesiated atmosphere. The cesium plasma helps to suppress the vaporization interference. The second area involved characterization of the Lanthanum-Boron series as thermionic emitters. These final two areas resulted in three journal publications which are attached to this report.

Aerosol jet printed silver nanowire transparent electrode for flexible electronic application

NASA Astrophysics Data System (ADS)

Tu, Li; Yuan, Sijian; Zhang, Huotian; Wang, Pengfei; Cui, Xiaolei; Wang, Jiao; Zhan, Yi-Qiang; Zheng, Li-Rong

2018-05-01

Aerosol jet printing technology enables fine feature deposition of electronic materials onto low-temperature, non-planar substrates without masks. In this work, silver nanowires (AgNWs) are proposed to be printed into transparent flexible electrodes using a Maskless Mesoscale Material Deposition Aerosol Jet® printing system on a glass substrate. The influence of the most significant process parameters, including printing cycles, printing speed, and nozzle size, on the performance of AgNW electrodes was systematically studied. The morphologies of printed patterns were characterized by scanning electron microscopy, and the transmittance was evaluated using an ultraviolet-visible spectrophotometer. Under optimum conditions, high transparent AgNW electrodes with a sheet resistance of 57.68 Ω/sq and a linewidth of 50.9 μm were obtained, which is an important step towards a higher performance goal for flexible electronic applications.

Polyaniline silver nanoparticle coffee waste extracted porous graphene oxide nanocomposite structures as novel electrode material for rechargeable batteries

NASA Astrophysics Data System (ADS)

Sundriyal, Poonam; Bhattacharya, Shantanu

2017-03-01

The exploration of new and advanced electrode materials are required in electronic and electrical devices for power storage applications. Also, there has been a continuous endeavour to formulate strategies for extraction of high performance electrode materials from naturally obtained waste products. In this work, we have developed an in situ hybrid nanocomposite from coffee waste extracted porous graphene oxide (CEPG), polyaniline (PANI) and silver nanoparticles (Ag) and have found this novel composite to serve as an efficient electrode material for batteries. The successful interaction among the three phases of the nano-composite i.e. CEPG-PANI-Ag have been thoroughly understood through RAMAN, Fourier transform infrared and x-ray diffraction spectroscopy, morphological studies through field emission scanning electron microscope and transmission electron microscope. Thermo-gravimetric analysis of the nano-composite demonstrates higher thermal stability up-to a temperature of 495 °C. Further BET studies through nitrogen adsorption-desorption isotherms confirm the presence of micro/meso and macro-pores in the nanocomposite sample. The cyclic-voltammetry (CV) analysis performed on CEPG-PANI-Ag nanocomposite exhibits a purely faradic behaviour using nickel foam as a current collector thus suggests the prepared nanocomposite as a battery electrode material. The nanocomposite reports a maximum specific capacity of 1428 C g-1 and excellent cyclic stability up-to 5000 cycles.

Direct conversion of CO 2 to meso/macro-porous frameworks of surface-microporous graphene for efficient asymmetrical supercapacitors

DOE PAGES

Chang, Liang; Stacchiola, Dario J.; Hu, Yun Hang

2017-10-11

CO 2 conversion to useful materials is the most attractive approach to control its content in the atmosphere. An ideal electrode material for supercapacitors should possess suitable meso/macro-pores as electrolyte reservoirs and rich micro-pores as places for the adsorption of electrolyte ions. In this paper, we designed and synthesized such an ideal material, meso/macro-porous frameworks of surface-microporous graphene (MFSMG), from CO 2via its one-step exothermic reaction with potassium. Furthermore, the MFSMG electrode exhibited a high gravimetric capacitance of 178 F g -1 at 0.2 A g -1 in 2 M KOH and retained 85% capacitance after increasing current density bymore » 50 times. The combination of the MFSMG electrode and the activated carbon (AC) electrode constructed an asymmetrical AC//MFSMG capacitor, leading to a high capacitance of 242.4 F g -1 for MFSMG and 97.4 F g -1 for AC. With the extended potential, the asymmetrical capacitor achieved an improved energy density of 9.43 W h kg -1 and a power density of 3504 W kg -1. Finally, this work provides a novel solution to solve the CO 2 issue and creates an efficient electrode material for supercapacitors.« less

Materials system for intermediate temperature solid oxide fuel cells based on doped lanthanum-gallate electrolyte

NASA Astrophysics Data System (ADS)

Gong, Wenquan

2005-07-01

The objective of this work was to identify a materials system for intermediate temperature solid oxide fuel cells (IT-SOFCs). Towards this goal, alternating current complex impedance spectroscopy was employed as a tool to study electrode polarization effects in symmetrical cells employing strontium and magnesium doped lanthanum gallate (LSGM) electrolyte. Several cathode materials were investigated including strontium doped lanthanum manganite (LSM), Strontium and iron doped lanthanum cobaltate (LSCF), LSM-LSGM, and LSCF-LSGM composites. Investigated Anode materials included nickel-gadolinium or lanthanum doped cerium oxide (Ni-GDC, or Ni-LDC) composites. The ohmic and the polarization resistances of the symmetrical cells were obtained as a function of temperature, time, thickness, and the composition of the electrodes. Based on these studies, the single phase LSM electrode had the highest polarization resistance among the cathode materials. The mixed-conducting LSCF electrode had polarization resistance orders of magnitude lower than that of the LSM-LSGM composite electrodes. Although incorporating LSGM in the LSCF electrode did not reduce the cell polarization resistance significantly, it could reduce the thermal expansion coefficient mismatch between the LSCF electrodes and LSGM electrolyte. Moreover, the polarization resistance of the LSCF electrode decreased asymptotically as the electrode thickness was increased thus suggesting that the electrode thickness needed not be thicker than this asymptotic limit. On the anode side of the IT-SOFC, Ni reacted with LSGM electrolyte, and lanthanum diffusion occurred from the LSGM electrolyte to the GDC barrier layer, which was between the LSGM electrolyte and the Ni-composite anode. However, LDC served as an effective barrier layer. Ni-LDC (70 v% Ni) anode had the largest polarization resistance, while all other anode materials, i.e. Ni-LDC (50 v% Ni), Ni-GDC (70 v% NO, and Ni-GDC (50 v% Ni), had similar polarization resistances. Ni-LDC (50 v% NO was selected to be the anode for the LSGM electrolyte with a thin LDC barrier layer. Finally, the performance of complete LSGM electrolyte-supported IT-SOFCs with the selected cathode (LSCF-LSGM) and anode (Ni-LDC) materials coupled with the LDC barrier layer was evaluated at 600--800°C. The simulated cell performance of the anode-supported cell based on LSGM electrolyte was promising.

Fabrication of graphene/polydopamine/copper foam composite material and its application as supercapacitor electrode

NASA Astrophysics Data System (ADS)

Zheng, Y.; Lu, S. X.; Xu, W. G.; He, G.; Cheng, Y. Y.; Xiao, F. Y.; Zhang, Y.

2018-01-01

In this work, a composite electrode was fabricated by chemical deposition of polydopamine (PDA) and graphene oxide (GO) on the copper foam (CF) surface, followed by annealing treatment. Owing to the cohesive effect of the PDA middle film, GO was coated on CF surface successfully, and then reduced simultaneously while annealing. The resulted rGO/PDA/CF composite electrode was directly used as a supercapacitor electrode and exhibited excellent electrochemical performance, with a high specific capacitance of 1250 F g-1 at 2 A g-1 and favorable cycle stability.

Polypyrrole electrodes doped with sulfanilic acid azochromotrop for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Chen, S.; Zhitomirsky, I.

2013-12-01

In this work we demonstrate the feasibility of deposition of polypyrrole (PPy) films by electropolymerization on stainless steel substrates and fabrication of PPy powders by chemical polymerization using sulfanilic acid azochromotrop (SPADNS) as a new anionic dopant. The problem of low adhesion of PPy films to stainless steel substrates is addressed by the use of SPADNS, which exhibits chelating properties, promoting film formation. The use of fine particles, prepared by the chemical polymerization method, allows impregnation of Ni foams and fabrication of porous electrodes with high materials loading for electrochemical supercapacitors (ES). PPy films and Ni foam based PPy electrodes show capacitive behaviour in Na2SO4 electrolyte. The electron microscopy studies, impedance spectroscopy data and analysis of the SPADNS structure provide an insight into the factors, controlling capacitive behaviour. The Ni foam based electrodes offer advantages of improved capacitive behaviour at high materials loadings and good cycling stability. The area normalized and volume normalized specific capacitances are as high as 5.43 F cm-2 and 93.6 F cm-3, respectively, for materials loading of 35.4 mg cm-2. The capacitance retention of Ni foam based electrodes is 91.5% after 1000 cycles. The Ni foam based PPy electrodes are promising for application in ES.

Exploring the electrochemical performance of graphitic paste electrodes: graphene vs. graphite.

PubMed

Figueiredo-Filho, Luiz C S; Brownson, Dale A C; Gómez-Mingot, Maria; Iniesta, Jesús; Fatibello-Filho, Orlando; Banks, Craig E

2013-11-07

We report the fabrication, characterisation (SEM, TEM, XPS and Raman spectroscopy) and electrochemical implementation of a graphene paste electrode. The paste electrodes utilised are constructed by simply mixing graphene with mineral oil (which acts as a binder) prior to loading the resultant paste into a piston-driven polymeric-tubing electrode-shell, where this electrode configuration allows for rapid renewal of the electrode surface. The fabricated paste electrode is electrochemically characterised using both inner-sphere and outer-sphere redox probes, namely potassium ferrocyanide(ii), hexaammine-ruthenium(iii) chloride and hexachloroiridate(iii), in addition to the biologically relevant and electroactive analytes, l-ascorbic acid (AA) and uric acid (UA). Comparisons are made with a graphite paste alternative and the benefits of graphene implementation as a paste electrode within electrochemistry are explored, as well as the characterisation of their electroanalytical performances. We reveal no observable differences in the electrochemical performance and thus suggest that there are no advantages of using graphene over graphite in the fabrication of paste electrodes. Such work is highly important and informative for those working in the field of electroanalysis where electrochemistry can provide portable, rapid, reliable and accurate sensing protocols (bringing the laboratory into the field), with particular relevance to those searching for new electrode materials.

Non-destructive control of graphite electrodes with use of current displacement effect

NASA Astrophysics Data System (ADS)

Myatezh, A. V.; Malozyomov, B. V.; Smirnov, M. A.

2017-10-01

The work is devoted to methods of nondestructive diagnostics and their use for solving the problem of diagnosing various defects in solid surface of graphite electrodes used in steelmaking furnaces. Various non-destructive control methods of materials are analyzed. In the article, methods of eddy-current defectoscopy of graphite electrodes are considered. Rationalization of the sensitivity increase of the method and localization of damage is described. Imitating modeling of electromagnetic processes was executed; results were made and conclusions were drawn.

Hierarchical porous carbon materials derived from petroleum pitch for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Abudu, Patiman; Wang, Luxiang; Xu, Mengjiao; Jia, Dianzeng; Wang, Xingchao; Jia, Lixia

2018-06-01

In this work, a honeycomb-like carbon material derived from petroleum pitch was synthesized by a simple one-step carbonization/activation method using silica nanospheres as the hard templates. The obtained hierarchical porous carbon materials (HPCs) with a large specific surface area and uniform macropore distribution provide abundant active sites and sufficient ion migration channels. When used as an electrode material for supercapacitors, the HPCs exhibit a high specific capacitance of 341.0 F g-1 at 1 A g-1, excellent rate capability with a capacitance retention of 55.6% at 50 A g-1 (189.5 F g-1), and outstanding cycling performance in the three-electrode system.

Research and analysis on electrochemical performances of α-Fe{sub 2}O{sub 3} electrode in Li-ion battery with different current collectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lihong, E-mail: huang.lihong@foxmail.com; Min, Zhonghua; Zhang, Qinyong

2015-06-15

Highlights: • We achieved a reversible capacity of 415 mAh g{sup −1} after 30 cycles for α-Fe{sub 2}O{sub 3} electrode in Li-ion battery. • Better electrical performance was obtained when using Cu foam as current collector. • As current collector for α-Fe{sub 2}O{sub 3} electrode, Cu foam is better than Cu foil and Ni foam. • It could avoid the active materials falling off from the current collector during cycling. • It is owe to smaller surface film resistance, charge-transfer resistance, etc. - Abstract: In this work, we reported a simple synthesis of submicron α-Fe{sub 2}O{sub 3} with rod-like structure.more » When it evaluated as electrode material for lithium ion battery, comparing with Cu foil and Ni foam, the as-prepared α-Fe{sub 2}O{sub 3} electrodes with Cu foam current collector exhibited higher reversible capacity of 415 mAh g{sup −1} and more stable cycle performance after 30 cycles. Comparative researches on electrochemical performances of the α-Fe{sub 2}O{sub 3} employing different current collectors (Cu foil, Cu foam and Ni foam) were discussed here in detail. According to our results, the improved electrochemical behaviors of α-Fe{sub 2}O{sub 3} electrode with Cu foam current collector could be attributed to its particular electrode structure, i.e., porous, good electric conductivity, closed adhere to the electrode materials. Just because of that, it may make sure an easy accessibility of electrolytes and fast transportation of lithium ions, importantly, it could avoid the active materials falling off from the current collector on account of volume expansion.« less

Ag Nanoparticles-Modified 3D Graphene Foam for Binder-Free Electrodes of Electrochemical Sensors.

PubMed

Han, Tao; Jin, Jianli; Wang, Congxu; Sun, Youyi; Zhang, Yinghe; Liu, Yaqing

2017-02-16

Ag nanoparticles-modified 3D graphene foam was synthesized through a one-step in-situ approach and then directly applied as the electrode of an electrochemical sensor. The composite foam electrode exhibited electrocatalytic activity towards Hg(II) oxidation with high limit of detection and sensitivity of 0.11 μM and 8.0 μA/μM, respectively. Moreover, the composite foam electrode for the sensor exhibited high cycling stability, long-term durability and reproducibility. These results were attributed to the unique porous structure of the composite foam electrode, which enabled the surface of Ag nanoparticles modified reduced graphene oxide (Ag NPs modified rGO) foam to become highly accessible to the metal ion and provided more void volume for the reaction with metal ion. This work not only proved that the composite foam has great potential application in heavy metal ions sensors, but also provided a facile method of gram scale synthesis 3D electrode materials based on rGO foam and other electrical active materials for various applications.

Ag Nanoparticles-Modified 3D Graphene Foam for Binder-Free Electrodes of Electrochemical Sensors

PubMed Central

Han, Tao; Jin, Jianli; Wang, Congxu; Sun, Youyi; Zhang, Yinghe; Liu, Yaqing

2017-01-01

Ag nanoparticles-modified 3D graphene foam was synthesized through a one-step in-situ approach and then directly applied as the electrode of an electrochemical sensor. The composite foam electrode exhibited electrocatalytic activity towards Hg(II) oxidation with high limit of detection and sensitivity of 0.11 µM and 8.0 µA/µM, respectively. Moreover, the composite foam electrode for the sensor exhibited high cycling stability, long-term durability and reproducibility. These results were attributed to the unique porous structure of the composite foam electrode, which enabled the surface of Ag nanoparticles modified reduced graphene oxide (Ag NPs modified rGO) foam to become highly accessible to the metal ion and provided more void volume for the reaction with metal ion. This work not only proved that the composite foam has great potential application in heavy metal ions sensors, but also provided a facile method of gram scale synthesis 3D electrode materials based on rGO foam and other electrical active materials for various applications. PMID:28336878

Electrical characterization of conductive textile materials and its evaluation as electrodes for venous occlusion plethysmography.

PubMed

Goy, C B; Dominguez, J M; Gómez López, M A; Madrid, R E; Herrera, M C

2013-08-01

The ambulatory monitoring of biosignals involves the use of sensors, electrodes, actuators, processing tools and wireless communication modules. When a garment includes these elements with the purpose of recording vital signs and responding to specific situations it is call a 'Smart Wearable System'. Over the last years several authors have suggested that conductive textile material (e-textiles) could perform as electrode for these systems. This work aims at implementing an electrical characterization of e-textiles and an evaluation of their ability to act as textile electrodes for lower extremity venous occlusion plethysmography (LEVOP). The e-textile electrical characterization is carried out using two experimental set-ups (in vitro evaluation). Besides, LEVOP records are obtained from healthy volunteers (in vivo evaluation). Standard Ag/AgCl electrodes are used for comparison in all tests. Results shown that the proposed e-textiles are suitable for LEVOP recording and a good agreement between evaluations (in vivo and in vitro) is found.

High surface area, low weight composite nickel fiber electrodes

NASA Technical Reports Server (NTRS)

Johnson, Bradley A.; Ferro, Richard E.; Swain, Greg M.; Tatarchuk, Bruce J.

1993-01-01

The energy density and power density of light weight aerospace batteries utilizing the nickel oxide electrode are often limited by the microstructures of both the collector and the resulting active deposit in/on the collector. Heretofore, these two microstructures were intimately linked to one another by the materials used to prepare the collector grid as well as the methods and conditions used to deposit the active material. Significant weight and performance advantages were demonstrated by Britton and Reid at NASA-LeRC using FIBREX nickel mats of ca. 28-32 microns diameter. Work in our laboratory investigated the potential performance advantages offered by nickel fiber composite electrodes containing a mixture of fibers as small as 2 microns diameter (Available from Memtec America Corporation). These electrode collectors possess in excess of an order of magnitude more surface area per gram of collector than FIBREX nickel. The increase in surface area of the collector roughly translates into an order of magnitude thinner layer of active material. Performance data and advantages of these thin layer structures are presented. Attributes and limitations of their electrode microstructure to independently control void volume, pore structure of the Ni(OH)2 deposition, and resulting electrical properties are discussed.

Three dimensional separation trap based on dielectrophoresis and use thereof

DOEpatents

Mariella, Jr., Raymond P.

2004-05-04

An apparatus is adapted to separate target materials from other materials in a flow containing the target materials and other materials. A dielectrophoretic trap is adapted to receive the target materials and the other materials. At least one electrode system is provided in the trap. The electrode system has a three-dimensional configuration. The electrode system includes a first electrode and a second electrode that are shaped and positioned relative to each such that application of an electrical voltage to the first electrode and the second electrode creates a dielectrophoretic force and said dielectrophoretic force does not reach zero between the first electrode and the second electrode.

Sol-gel thin-film based mesoporous silica and carbon nanotubes for the determination of dopamine, uric acid and paracetamol in urine.

PubMed

Canevari, Thiago C; Raymundo-Pereira, Paulo A; Landers, Richard; Benvenutti, Edilson V; Machado, Sérgio A S

2013-11-15

This work describes the preparation, characterization and application of a hybrid material composed of disordered mesoporous silica (SiO2) modified with multiwalled carbon nanotubes (MWCNTs), obtained by the sol-gel process using HF as the catalyst. This hybrid material was characterized by N2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HR-TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This new hybrid material was used for the construction of a thin film on a glassy carbon electrode. The modified electrode using this material was designated SiO2/MWCNT/GCE. The electrocatalytic properties of the electrode toward dopamine, uric acid and paracetamol oxidation were studied by differential pulse voltammetry. Well-defined and separated oxidation peaks were observed in phosphate buffer solution at pH 7.0, in contrast with the ill-defined peaks observed with unmodified glassy carbon electrodes. The electrode had high sensitivity for the determination of dopamine, uric acid and paracetamol, with the limits of detection obtained using statistical methods, at 0.014, 0.068 and 0.098 µmol L(-1), respectively. The electrode presented some important advantages, including enhanced physical rigidity, surface renewability by polishing and high sensitivity, allowing the simultaneous determination of these three analytes in a human urine sample. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Ferromagnetic, folded electrode composite as a soft interface to the skin for long-term electrophysiological recording.

PubMed

Jang, Kyung-In; Jung, Han Na; Lee, Jung Woo; Xu, Sheng; Liu, Yu Hao; Ma, Yinji; Jeong, Jae-Woong; Song, Young Min; Kim, Jeonghyun; Kim, Bong Hun; Banks, Anthony; Kwak, Jean Won; Yang, Yiyuan; Shi, Dawei; Wei, Zijun; Feng, Xue; Paik, Ungyu; Huang, Yonggang; Ghaffari, Roozbeh; Rogers, John A

2016-10-25

This paper introduces a class of ferromagnetic, folded, soft composite material for skin-interfaced electrodes with releasable interfaces to stretchable, wireless electronic measurement systems. These electrodes establish intimate, adhesive contacts to the skin, in dimensionally stable formats compatible with multiple days of continuous operation, with several key advantages over conventional hydrogel based alternatives. The reported studies focus on aspects ranging from ferromagnetic and mechanical behavior of the materials systems, to electrical properties associated with their skin interface, to system-level integration for advanced electrophysiological monitoring applications. The work combines experimental measurement and theoretical modeling to establish the key design considerations. These concepts have potential uses across a diverse set of skin-integrated electronic technologies.

Simultaneous control of thermoelectric properties in p- and n-type materials by electric double-layer gating: New design for thermoelectric device

NASA Astrophysics Data System (ADS)

Takayanagi, Ryohei; Fujii, Takenori; Asamitsu, Atsushi

2015-05-01

We report a novel design of a thermoelectric device that can control the thermoelectric properties of p- and n-type materials simultaneously by electric double-layer gating. Here, p-type Cu2O and n-type ZnO were used as the positive and negative electrodes of the electric double-layer capacitor structure. When a gate voltage was applied between the two electrodes, holes and electrons accumulated on the surfaces of Cu2O and ZnO, respectively. The thermopower was measured by applying a thermal gradient along the accumulated layer on the electrodes. We demonstrate here that the accumulated layers worked as a p-n pair of the thermoelectric device.

From Rome to Como: 20 years of active research on carbon-based electrodes for lithium batteries at INP-Grenoble

NASA Astrophysics Data System (ADS)

Yazami, Rachid

This paper reviews the main areas of research performed at different Laboratories of the Institut National Polytechnique de Grenoble (INPG) over the past 20 years, specifically on cabonaceous materials for electrode applications in lithium batteries. The most significant event was the discovery in the early 1980s of reversible lithium intercalation into graphite in polymer electrolytes, which led to the use of this material in today's lithium-ion batteries. Important work was also carried out on positive electrode for primary and secondary batteries, especially graphite oxide and graphite fluoride. Most of these results were presented at the 10 IMLB series Symposia, which started in Rome in 1982 and were back to Como, Italy, in 2000.

Piezo-Electrochemical Energy Harvesting with Lithium-Intercalating Carbon Fibers.

PubMed

Jacques, Eric; Lindbergh, Göran; Zenkert, Dan; Leijonmarck, Simon; Kjell, Maria Hellqvist

2015-07-01

The mechanical and electrochemical properties are coupled through a piezo-electrochemical effect in Li-intercalated carbon fibers. It is demonstrated that this piezo-electrochemical effect makes it possible to harvest electrical energy from mechanical work. Continuous polyacrylonitrile-based carbon fibers that can work both as electrodes for Li-ion batteries and structural reinforcement for composites materials are used in this study. Applying a tensile force to carbon fiber bundles used as Li-intercalating electrodes results in a response of the electrode potential of a few millivolts which allows, at low current densities, lithiation at higher electrode potential than delithiation. More electrical energy is thereby released from the cell at discharge than provided at charge, harvesting energy from the mechanical work of the applied force. The measured harvested specific electrical power is in the order of 1 μW/g for current densities in the order of 1 mA/g, but this has a potential of being increased significantly.

Recycling positive-electrode material of a lithium-ion battery

DOEpatents

Sloop, Steven E.

2017-11-21

Examples are disclosed of methods to recycle positive-electrode material of a lithium-ion battery. In one example, the positive-electrode material is heated under pressure in a concentrated lithium hydroxide solution. After heating, the positive-electrode material is separated from the concentrated lithium hydroxide solution. After separating, the positive electrode material is rinsed in a basic liquid. After rinsing, the positive-electrode material is dried and sintered.

Sol-gel spin coated well adhered MoO3 thin films as an alternative counter electrode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Mutta, Geeta R.; Popuri, Srinivasa R.; Wilson, John I. B.; Bennett, Nick S.

2016-11-01

In this work, we aim to develop a viable, inexpensive and non-toxic material for counter electrodes in dye sensitized solar cells (DSSCs). We employed an ultra-simple synthesis process to deposit MoO3 thin films at low temperature by sol-gel spin coating technique. These MoO3 films showed good transparency. It is predicted that there will be 150 times reduction of precursors cost by realizing MoO3 thin films as a counter electrode in DSSCs compared to commercial Pt. We achieved a device efficiency of about 20 times higher than that of the previous reported values. In summary we develop a simple low cost preparation of MoO3 films with an easily scaled up process along with good device efficiency. This work encourages the development of novel and relatively new materials and paves the way for massive reduction of industrial costs which is a prime step for commercialization of DSSCs.

Low contact resistance of the MWCNTs ohmic contact to p-GaN and its application for high power LED

NASA Astrophysics Data System (ADS)

Yokogawa, Toshiya; Miyake, Syota

2017-08-01

A low contact resistance electrode for p-GaN was obtained using the metallic multi-wall carbon nanotubes (MWCNTs) as the electrode material. The work function of the metallic MWCNTs was confirmed to be 4.84 eV as large as that of Au, Pd and Ni which are generally used for the p-GaN electrode material. Consequently the specific contact resistance was obtained to be as low as 2×10-3 Ωcm2 by optimizing the GaN surface treatment using hydrochloric acid because of the large work function of the MWCNTs. We also characterized the properties of LEDs using the MWCNTs ohmic contact for p-GaN. Low operation voltage and high optical output power was successfully obtained. Threshold voltage was about 2.7 V, and optical output power was about 0.8 W for the 1×1 mm2 size LED chip.

Conductive polymer/reduced graphene oxide/Au nano particles as efficient composite materials in electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Shabani Shayeh, J.; Ehsani, A.; Ganjali, M. R.; Norouzi, P.; Jaleh, B.

2015-10-01

Polyaniline/reduced graphene oxide/Au nano particles (PANI/rGO/AuNPs) as a hybrid supercapacitor were deposited on a glassy carbon electrode (GCE) by cyclic voltammetry (CV) method as ternary composites and their electrochemical performance was evaluated in acidic medium. Scanning electron micrographs clearly revealed the formation of nanocomposites on the surface of the working electrode. Scanning electron micrographs (SEM) clearly revealed the formation of nanocomposites on the surface of working electrode. Different electrochemical methods including galvanostatic charge-discharge (CD) experiments, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out in order to investigate the applicability of the system as a supercapacitor. Based on the cyclic voltammogram results obtained, PANI/rGO/AuNPs gave higher specific capacitance, power and energy values than PANI at a current density of 1 mA cm-2. Specific capacitance (SC) of PANI and PANI/rGO/AuNPs electrodes calculated using CV method are 190 and 303 F g-1, respectively. The present study introduces new nanocomposite materials for electrochemical redox capacitors with advantages including long life cycle and stability due to synergistic effects of each component.

High-performance NiO/Ag/NiO transparent electrodes for flexible organic photovoltaic cells.

PubMed

Xue, Zhichao; Liu, Xingyuan; Zhang, Nan; Chen, Hong; Zheng, Xuanming; Wang, Haiyu; Guo, Xiaoyang

2014-09-24

Transparent electrodes with a dielectric-metal-dielectric (DMD) structure can be implemented in a simple manufacturing process and have good optical and electrical properties. In this study, nickel oxide (NiO) is introduced into the DMD structure as a more appropriate dielectric material that has a high conduction band for electron blocking and a low valence band for efficient hole transport. The indium-free NiO/Ag/NiO (NAN) transparent electrode exhibits an adjustable high transmittance of ∼82% combined with a low sheet resistance of ∼7.6 Ω·s·q(-1) and a work function of 5.3 eV after UVO treatment. The NAN electrode shows excellent surface morphology and good thermal, humidity, and environmental stabilities. Only a small change in sheet resistance can be found after NAN electrode is preserved in air for 1 year. The power conversion efficiencies of organic photovoltaic cells with NAN electrodes deposited on glass and polyethylene terephthalate (PET) substrates are 6.07 and 5.55%, respectively, which are competitive with those of indium tin oxide (ITO)-based devices. Good photoelectric properties, the low-cost material, and the room-temperature deposition process imply that NAN electrode is a striking candidate for low-cost and flexible transparent electrode for efficient flexible optoelectronic devices.

Digested sludge-derived three-dimensional hierarchical porous carbon for high-performance supercapacitor electrode.

PubMed

Zhang, Jia-Jia; Fan, Hao-Xiang; Dai, Xiao-Hu; Yuan, Shi-Jie

2018-04-01

Digested sludge, as the main by-product of the sewage sludge anaerobic digestion process, still contains considerable organic compounds. In this protocol, we report a facile method for preparing digested sludge-derived self-doped porous carbon material for high-performance supercapacitor electrodes via a sustainable pyrolysis/activation process. The obtained digested sludge-derived carbon material (HPDSC) exhibits versatile O-, N-doped hierarchical porous framework, high specific surface area (2103.6 m 2  g -1 ) and partial graphitization phase, which can facilitate ion transport, provide more storage sites for electrolyte ions and enhance the conductivity of active electrode materials. The HPDSC-based supercapacitor electrodes show favourable energy storage performance, with a specific capacitance of 245 F g -1 at 1.0 A g -1 in 0.5 M Na 2 SO 4 ; outstanding cycling stability, with 98.4% capacitance retention after 2000 cycles; and good rate performance (211 F g -1 at 11 A g -1 ). This work provides a unique self-doped three-dimensional hierarchical porous carbon material with a favourable charge storage capacity and at the same time finds a high value-added and environment-friendly strategy for disposal and recycling of digested sludge.

Digested sludge-derived three-dimensional hierarchical porous carbon for high-performance supercapacitor electrode

NASA Astrophysics Data System (ADS)

Zhang, Jia-Jia; Fan, Hao-Xiang; Dai, Xiao-Hu; Yuan, Shi-Jie

2018-04-01

Digested sludge, as the main by-product of the sewage sludge anaerobic digestion process, still contains considerable organic compounds. In this protocol, we report a facile method for preparing digested sludge-derived self-doped porous carbon material for high-performance supercapacitor electrodes via a sustainable pyrolysis/activation process. The obtained digested sludge-derived carbon material (HPDSC) exhibits versatile O-, N-doped hierarchical porous framework, high specific surface area (2103.6 m2 g-1) and partial graphitization phase, which can facilitate ion transport, provide more storage sites for electrolyte ions and enhance the conductivity of active electrode materials. The HPDSC-based supercapacitor electrodes show favourable energy storage performance, with a specific capacitance of 245 F g-1 at 1.0 A g-1 in 0.5 M Na2SO4; outstanding cycling stability, with 98.4% capacitance retention after 2000 cycles; and good rate performance (211 F g-1 at 11 A g-1). This work provides a unique self-doped three-dimensional hierarchical porous carbon material with a favourable charge storage capacity and at the same time finds a high value-added and environment-friendly strategy for disposal and recycling of digested sludge.

A rationally designed self-standing V2O5 electrode for high voltage non-aqueous all-solid-state symmetric (2.0 V) and asymmetric (2.8 V) supercapacitors.

PubMed

Ghosh, Meena; Vijayakumar, Vidyanand; Soni, Roby; Kurungot, Sreekumar

2018-05-10

The maximum capacitive potential window of certain pseudocapacitive materials cannot be accessed in aqueous electrolytes owing to the low dissociation potential of 1.2 V possessed by water molecules. However, the inferior pseudocapacitance exhibited by the commonly used electrode materials when integrated with non-aqueous electrolytes still remains a challenge in the development of supercapacitors (SC). Proper selection of materials for the electrode and a rational design process are indeed important to overcome these practical intricacies so that such systems can perform well with non-aqueous electrolytes. We address this challenge by fabricating a prototype all-solid-state device designed with high-capacitive V2O5 as the electrode material along with a Li-ion conducting organic electrolyte. V2O5 is synthesized on a pre-treated carbon-fibre paper by adopting an electrochemical deposition technique that effects an improved contact resistance. A judicious electrode preparation strategy makes it possible to overcome the constraints of the low ionic and electrical conductivities imposed by the electrolyte and electrode material, respectively. The device, assembled in a symmetrical fashion, achieves a high specific capacitance of 406 F g-1 (at 1 A g-1). The profitable aspect of using an organic electrolyte is also demonstrated with an asymmetric configuration by using activated carbon as the positive and V2O5 as the negative electrode materials, respectively. The asymmetric device displays a wide working-voltage window of 2.8 V and delivers a high energy density of 102.68 W h kg-1 at a power density of 1.49 kW kg-1. Moreover, the low equivalent series resistance of 9.9 Ω and negligible charge transfer resistance are observed in the impedance spectra, which is a key factor that accounts for such an exemplary performance.

Electrode architectures for efficient electronic and ionic transport pathways in high power lithium ion batteries

NASA Astrophysics Data System (ADS)

Faulkner, Ankita Shah

As the demand for clean energy sources increases, large investments have supported R&D programs aimed at developing high power lithium ion batteries for electric vehicles, military, grid storage and space applications. State of the art lithium ion technology cannot meet power demands for these applications due to high internal resistances in the cell. These resistances are mainly comprised of ionic and electronic resistance in the electrode and electrolyte. Recently, much attention has been focused on the use of nanoscale lithium ion active materials on the premise that these materials shorten the diffusion length of lithium ions and increase the surface area for electrochemical charge transfer. While, nanomaterials have allowed significant improvements in the power density of the cell, they are not a complete solution for commercial batteries. Due to their large surface area, they introduce new challenges such as a poor electrode packing densities, high electrolyte reactivity, and expensive synthesis procedures. Since greater than 70% of the cost of the electric vehicle is due to the cost of the battery, a cost-efficient battery design is most critical. To address the limitations of nanomaterials, efficient transport pathways must be engineered in the bulk electrode. As a part of nanomanufacturing research being conducted the Center for High-rate Nanomanufacturing at Northeastern University, the first aim of the proposed work is to develop electrode architectures that enhance electronic and ionic transport pathways in large and small area lithium ion electrodes. These architectures will utilize the unique electronic and mechanical properties of carbon nanotubes to create robust electrode scaffolding that improves electrochemical charge transfer. Using extensive physical and electrochemical characterization, the second aim is to investigate the effect of electrode parameters on electrochemical performance and evaluate the performance against standard commercial electrodes. These parameters include surface morphology, electrode composition, electrode density, and operating temperature. Finally, the third aim is to investigate commercial viability of the electrode architecture. This will be accomplished by developing pouch cell prototypes using a high-rate and low cost scale-up process. Through this work, we aim to realize a commercially viable high-power electrode technology.

Low-threshold field emission in planar cathodes with nanocarbon materials

NASA Astrophysics Data System (ADS)

Zhigalov, V.; Petukhov, V.; Emelianov, A.; Timoshenkov, V.; Chaplygin, Yu.; Pavlov, A.; Shamanaev, A.

2016-12-01

Nanocarbon materials are of great interest as field emission cathodes due to their low threshold voltage. In this work current-voltage characteristics of nanocarbon electrodes were studied. Low-threshold emission was found in planar samples where field enhancement is negligible (<10). Electron work function values, calculated by Fowler-Nordheim theory, are anomalous low (<1 eV) and come into collision with directly measured work function values in fabricated planar samples (4.1-4.4 eV). Non-applicability of Fowler-Nordheim theory for the nanocarbon materials was confirmed. The reasons of low-threshold emission in nanocarbon materials are discussed.

Nitrogen-doped carbon spheres: A new high-energy-density and long-life pseudo-capacitive electrode material for electrochemical flow capacitor.

PubMed

Hou, Shujin; Wang, Miao; Xu, Xingtao; Li, Yandong; Li, Yanjiang; Lu, Ting; Pan, Likun

2017-04-01

One of the most challenging issues in developing electrochemical flow capacitor (EFC) technology is the design and synthesis of active electrode materials with high energy density and long cycle life. However, in practical cases, the energy density and cycle ability obtained currently cannot meet the practical need. In this work, we propose a new active material, nitrogen-doped carbon spheres (NCSs), as flowable electrodes for EFC application. The NCSs were prepared via one-pot hydrothermal synthesis in the presence of resorcinol/formaldehyde as carbon precursors and melamine as nitrogen precursor, followed by carbonization in nitrogen flow at various temperatures. The results of EFC experiments demonstrate that NCSs obtained at 800°C exhibit a high energy density of 13.5Whkg -1 and an excellent cycle ability, indicating the superiority of NCSs for EFC application. Copyright © 2016 Elsevier Inc. All rights reserved.

Tetra-heteroatom self-doped carbon nanosheets derived from silkworm excrement for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Lei, Shuijin; Chen, Lianfu; Zhou, Wei; Deng, Peiqin; Liu, Yan; Fei, Linfeng; Lu, Wei; Xiao, Yanhe; Cheng, Baochang

2018-03-01

Carbon materials are deemed to be competitive candidate electrode materials for energy storage systems. It is still a great challenge to explore advanced carbon-based electrode materials for high-performance supercapacitors by a facile, economical and efficient method. In this work, N-, P-, S-, O-self-doped carbon nanosheets with high surface area and well-developed porosity are successfully prepared by pyrolysis carbonization and post KOH activation from silkworm excrement, a novel abundant, low-cost and eco-friendly agricultural waste. Thanks to their unique multi-heteroatom doping and porous structure, the obtained carbon materials exhibit high charge storage capacity with a specific capacitance of 401 F g-1 at a current density of 0.5 A g-1 in 6 M KOH and good cycling stability with a capacitance retention of 93.8% over 10000 cycles. A symmetric supercapacitor device using 1 M Na2SO4 aqueous solution as the electrolyte can deliver a specific capacitance of 41.7 F g-1 at a current density of 0.5 A g-1, and a high energy density of 23.17 Wh kg-1 at a power density of 500 W kg-1 with a wide voltage window of 2.0 V. This work develops a new strategy to produce favorable carbon-based electrode materials for supercapacitors with high electrochemical performances.

2D nanosheet molybdenum disulphide (MoS2) modified electrodes explored towards the hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Rowley-Neale, Samuel J.; Brownson, Dale A. C.; Smith, Graham C.; Sawtell, David A. G.; Kelly, Peter J.; Banks, Craig E.

2015-10-01

We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite electrodes (SPE), we critically evaluate the reported electrocatalytic performance of unmodified and MoS2 modified electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underlying support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet modified electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD electrodes compared to their unmodified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrode's individual electron transfer kinetics/properties and is thus distinct. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER.We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite electrodes (SPE), we critically evaluate the reported electrocatalytic performance of unmodified and MoS2 modified electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underlying support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet modified electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD electrodes compared to their unmodified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrode's individual electron transfer kinetics/properties and is thus distinct. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05164a|ART

Molecular Engineering with Organic Carbonyl Electrode Materials for Advanced Stationary and Redox Flow Rechargeable Batteries.

PubMed

Zhao, Qing; Zhu, Zhiqiang; Chen, Jun

2017-12-01

Organic carbonyl electrode materials that have the advantages of high capacity, low cost and being environmentally friendly, are regarded as powerful candidates for next-generation stationary and redox flow rechargeable batteries (RFBs). However, low carbonyl utilization, poor electronic conductivity and undesired dissolution in electrolyte are urgent issues to be solved. Here, we summarize a molecular engineering approach for tuning the capacity, working potential, concentration of active species, kinetics, and stability of stationary and redox flow batteries, which well resolves the problems of organic carbonyl electrode materials. As an example, in stationary batteries, 9,10-anthraquinone (AQ) with two carbonyls delivers a capacity of 257 mAh g -1 (2.27 V vs Li + /Li), while increasing the number of carbonyls to four with the formation of 5,7,12,14-pentacenetetrone results in a higher capacity of 317 mAh g -1 (2.60 V vs Li + /Li). In RFBs, AQ, which is less soluble in aqueous electrolyte, reaches 1 M by grafting -SO 3 H with the formation of 9,10-anthraquinone-2,7-disulphonic acid, resulting in a power density exceeding 0.6 W cm -2 with long cycling life. Therefore, through regulating substituent groups, conjugated structures, Coulomb interactions, and the molecular weight, the electrochemical performance of carbonyl electrode materials can be rationally optimized. This review offers fundamental principles and insight into designing advanced carbonyl materials for the electrodes of next-generation rechargeable batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Construction of porous CuCo2S4 nanorod arrays via anion exchange for high-performance asymmetric supercapacitor.

PubMed

Cheng, Siyi; Shi, Tielin; Chen, Chen; Zhong, Yan; Huang, Yuanyuan; Tao, Xiangxu; Li, Junjie; Liao, Guanglan; Tang, Zirong

2017-07-27

To push the energy density limit of supercapacitors, proper pseudocapacitive materials with favorable nanostructures are urgently pursued. Ternary transition metal sulfides are promising electrode materials due to the better conductivity and higher electrochemical activity in comparison to the single element sulfides and transition metal oxides. In this work, we have successfully synthesized porous CuCo 2 S 4 nanorod array (NRAs) on carbon textile through a stepwise hydrothermal method, including the growth of the Cu-Co precursor nanowire arrays and subsequent conversion into CuCo 2 S 4 NRAs via anion exchange reaction. The CuCo 2 S 4 NRAs electrode exhibits a greatly enhanced specific capacitance and an outstanding cycling stability. Moreover, an asymmetric supercapacitor using the CuCo 2 S 4 NRAs as positive electrode and activated carbon as negative electrode delivers a high energy density of 56.96 W h kg -1 . Such superior performance demonstrate that the CuCo 2 S 4 NRAs are promising materials for future energy storage applications.

Dye Wastewater Cleanup by Graphene Composite Paper for Tailorable Supercapacitors.

PubMed

Yu, Dandan; Wang, Hua; Yang, Jie; Niu, Zhiqiang; Lu, Huiting; Yang, Yun; Cheng, Liwei; Guo, Lin

2017-06-28

Currently, the energy crisis and environmental pollution are two critical challenges confronted by humans. The development of smart strategies to address the above-mentioned issues simultaneously is significant. As the main accomplices for water pollution, several kinds of organic dyes with intrinsic redox functional groups such as phenothiazines derivatives, anthraquinone, and indigoid dyes are potential candidates for the replacement of the conventional pseudocapacitive materials. In this work, three typical organic dyes can be efficiently removed by a facile adsorption procedure using reduced graphene oxide coated cellulose fiber (rGO@CF) paper. Flexible supercapacitors based on dye/rGO@CF electrodes exhibit excellent electrochemical performances that are superior to or comparable with those of conventional pseudocapacitive materials based devices, presenting a new type of promising electrode materials. Moreover, benefiting from the high flexibility and considerable mechanical strength of the graphene composite paper, the operating potential and capacitance of the devices can be easily adjusted by tailoring the hybrid electrodes into different specific shapes followed by rational integrating. The smart design of these dye/rGO@CF paper based electrodes shows that energy storage and environmental remediation can be achieved simultaneously.

Double-shell CuS nanocages as advanced supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

Guo, Jinxue; Zhang, Xinqun; Sun, Yanfang; Zhang, Xiaohong; Tang, Lin; Zhang, Xiao

2017-07-01

Metal sulfides hollow structures are advanced materials for energy storage applications of lithium-ion batteries and supercapacitors. However, constructing hollow metal sulfides with specific features, such as multi-shell and non-spherical shape, still remains great challenge. In this work, we firstly demonstrate the synthesis of CuS double-shell hollow nanocages using Cu2O nanocubes as precursors. The synthesis processes involve the repeated anion exchange reaction with Na2S and the controllable etching using hydrochloric acid. The whole synthesis processes are well revealed and the obtained double-shell CuS is tested as pseudocapacitive electrode material for supercapacitors. As expected, the CuS double-shell hollow nanocages deliver high specific capacitance, good rate performance and excellent cycling stability due to their unique nano-architecture. The present work contributes greatly to the exploration of hollow metal sulfides with complex architecture and non-spherical shape, as well as their promising application in high-performance electrochemical supercapacitors.

First-principles study of mixed eldfellite compounds Nax(Fe1/2M1/2) (SO4)2 (x=0-2, M = Mn, Co, Ni): A new family of high electrode potential cathodes for the sodium-ion battery

NASA Astrophysics Data System (ADS)

Ri, Gum-Chol; Choe, Song-Hyok; Yu, Chol-Jun

2018-02-01

Natural abundance of sodium and its similar behavior to lithium triggered recent extensive studies of cost-effective sodium-ion batteries (SIBs) for large-scale energy storage systems. A challenge is to develop electrode materials with a high electrode potential, specific capacity and a good rate capability. In this work we propose mixed eldfellite compounds Nax(Fe1/2M1/2) (SO4)2 (x = 0-2, M = Mn, Co, Ni) as a new family of high electrode potential cathodes of SIBs and present their material properties predicted by first-principles calculations. The structural optimizations show that these materials have significantly small volume expansion rates below 5% upon Na insertion/desertion with negative Na binding energies. Through the electronic structure calculations, we find band insulating properties and hole (and/or electron) polaron hoping as a possible mechanism for the charge transfer. Especially we confirm the high electrode voltages over 4 V with reasonably high specific capacities. We also investigate the sodium ion mobility by estimating plausible diffusion pathways and calculating the corresponding activation barriers, demonstrating the reasonably fast migrations of sodium ions during the operation. Our calculation results indicate that these mixed eldfellite compounds can be suitable materials for high performance SIB cathodes.

Copper Mesh Templated by Breath-Figure Polymer Films as Flexible Transparent Electrodes for Organic Photovoltaic Devices.

PubMed

Zhou, Weixin; Chen, Jun; Li, Yi; Wang, Danbei; Chen, Jianyu; Feng, Xiaomiao; Huang, Zhendong; Liu, Ruiqing; Lin, Xiujing; Zhang, Hongmei; Mi, Baoxiu; Ma, Yanwen

2016-05-04

Metal mesh is a significant candidate of flexible transparent electrodes to substitute the current state-of-the-art material indium tin oxide (ITO) for future flexible electronics. However, there remains a challenge to fabricate metal mesh with order patterns by a bottom-up approach. In this work, high-quality Cu mesh transparent electrodes with ordered pore arrays are prepared by using breath-figure polymer films as template. The optimal Cu mesh films present a sheet resistance of 28.7 Ω·sq(-1) at a transparency of 83.5%. The work function of Cu mesh electrode is tuned from 4.6 to 5.1 eV by Ag deposition and the following short-time UV-ozone treatment, matching well with the PSS (5.2 eV) hole extraction layer. The modified Cu mesh electrodes show remarkable potential as a substitute of ITO/PET in the flexible OPV and OLED devices. The OPV cells constructed on our Cu mesh electrodes present a similar power conversion efficiency of 2.04% as those on ITO/PET electrodes. The flexible OLED prototype devices can achieve a brightness of 10 000 cd at an operation voltage of 8 V.

Effects of pulse ON and OFF time and electrode types on the material removal rate and tool wear rate of the Ti-6Al-4V Alloy using EDM machining with reverse polarity

NASA Astrophysics Data System (ADS)

Praveen, L.; Geeta Krishna, P.; Venugopal, L.; Prasad, N. E. C.

2018-03-01

Electrical Discharge Machining (EDM) is an unconventional metal removal process that is extensively used for removing the difficult-to-machine metal such as Ti alloys, super alloys and metal matrix composites. This paper investigates the effects of pulse (ON/OFF) time on EDM machining characteristics of Ti-6Al-4V alloy using copper and graphite as electrodes in reverse polarity condition. Full factorial design method was used to design the experiments. Two variables (Pulse On and OFF) with three levels are considered. The output variables are the tool wear rate and the material removal rate. The important findings from the present work are: (1) the material removal rate (MRR) increases gradually with an increase of the Pulse ON time whereas the change is insignificant with an increase of the Pulse OFF time, (2) Between copper and graphite electrodes, the copper electrode is proved to be good in terms of MRR, (3) a combination of high pulse ON time and OFF time is desirable for high MRR rate in the Cu electrode whereas for the graphite electrode, a combination of high pulse ON time and low pulse OFF time is desirable for high MRR rate, (4) the tool wear rate (TWR) reduces with the Pulse On or OFF time, the rate of TWR is uniform for the graphite electrode in contrast to abrupt decrease from 25 to 50 μs (pulse ON time) in the copper electrode, (5) In order to keep the TWR as minimum possible, it is desirable to have a combination of high pulse ON time and OFF time for both the copper and the graphite electrode.

2D nanosheet molybdenum disulphide (MoS2) modified electrodes explored towards the hydrogen evolution reaction.

PubMed

Rowley-Neale, Samuel J; Brownson, Dale A C; Smith, Graham C; Sawtell, David A G; Kelly, Peter J; Banks, Craig E

2015-11-21

We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite electrodes (SPE), we critically evaluate the reported electrocatalytic performance of unmodified and MoS2 modified electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underlying support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet modified electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD electrodes compared to their unmodified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrode's individual electron transfer kinetics/properties and is thus distinct. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER.

Electrode Nanostructures in Lithium‐Based Batteries

PubMed Central

Mahmood, Nasir

2014-01-01

Lithium‐based batteries possessing energy densities much higher than those of the conventional batteries belong to the most promising class of future energy devices. However, there are some fundamental issues related to their electrodes which are big roadblocks in their applications to electric vehicles (EVs). Nanochemistry has advantageous roles to overcome these problems by defining new nanostructures of electrode materials. This review article will highlight the challenges associated with these chemistries both to bring high performance and longevity upon considering the working principles of the various types of lithium‐based (Li‐ion, Li‐air and Li‐S) batteries. Further, the review discusses the advantages and challenges of nanomaterials in nanostructured electrodes of lithium‐based batteries, concerns with lithium metal anode and the recent advancement in electrode nanostructures. PMID:27980896

Electrode Nanostructures in Lithium-Based Batteries.

PubMed

Mahmood, Nasir; Hou, Yanglong

2014-12-01

Lithium-based batteries possessing energy densities much higher than those of the conventional batteries belong to the most promising class of future energy devices. However, there are some fundamental issues related to their electrodes which are big roadblocks in their applications to electric vehicles (EVs). Nanochemistry has advantageous roles to overcome these problems by defining new nanostructures of electrode materials. This review article will highlight the challenges associated with these chemistries both to bring high performance and longevity upon considering the working principles of the various types of lithium-based (Li-ion, Li-air and Li-S) batteries. Further, the review discusses the advantages and challenges of nanomaterials in nanostructured electrodes of lithium-based batteries, concerns with lithium metal anode and the recent advancement in electrode nanostructures.

Dilute phosphide nitride materials as photocathodes for electrochemical solar energy conversion

NASA Astrophysics Data System (ADS)

Parameshwaran, Vijay; Xu, Xiaoqing; Kang, Yangsen; Harris, James; Wong, H.-S. Philip; Clemens, Bruce

2013-03-01

Dilute nitride materials have been used in a variety of III-V photonic devices, but have not been significantly explored in photoelectrochemical applications. This work focuses on using dilute phosphide nitride materials of the form (Al,In)P1-xNx as photocathodes for the generation of hydrogen fuel from solar energy. Heteroepitaxial MOCVD growth of AlPN thin films on GaP yields high quality material with a direct bandgap energy of 2.218 eV. Aligned epitaxial growth of InP and GaP nanowires on InP and Si substrates, respectively, provides a template for designing nanostructured photocathodes over a large area. Electrochemical testing of a AlPN/GaP heterostructure electrode yields up to a sixfold increase in photocurrent enhancement under blue light illumination as compared to a GaP electrode. Additionally, the AlPN/GaP electrodes exhibit no degradation in performance after galvanostatic biasing over time. These results show that (Al,In)P1-xNx is a promising materials system for use in nanoscale photocathode structures.

Method of measuring interface area of activated carbons in condensed phase

NASA Astrophysics Data System (ADS)

Dmitriyev, D. S.; Agafonov, D. V.; Kiseleva, E. A.; Mikryukova, M. A.

2018-01-01

In this work, we investigated the correlation between the heat of wetting of super-capacitor electrode material (activated carbon) with condensed phases (electrolytes based on homologous series of phosphoric acid esters) and the capacity of the supercapacitor. The surface area of the electrode-electrolyte interface was calculated according to the obtained correlations using the conventional formula for calculating the capacitance of a capacitor.

Probing potential Li-ion battery electrolyte through first principles simulation of atomic clusters

NASA Astrophysics Data System (ADS)

Kushwaha, Anoop Kumar; Sahoo, Mihir Ranjan; Nayak, Saroj

2018-04-01

Li-ion battery has wide area of application starting from low power consumer electronics to high power electric vehicles. However, their large scale application in electric vehicles requires further improvement due to their low specific power density which is an essential parameter and is closely related to the working potential windows of the battery system. Several studies have found that these parameters can be taken care of by considering different cathode/anode materials and electrolytes. Recently, a unique approach has been reported on the basis of cluster size in which the use of Li3 cluster has been suggested as a potential component of the battery electrode material. The cluster based approach significantly enhances the working electrode potential up to 0.6V in the acetonitrile solvent. In the present work, using ab-initio quantum chemical calculation and the dielectric continuum model, we have investigated various dielectric solvent medium for the suitable electrolyte for the potential component Li3 cluster. This study suggests that high dielectric electrolytic solvent (ethylene carbonate and propylene carbonate) could be better for lithium cluster due to improvement in the total electrode potential in comparison to the other dielectric solvent.

Modification of Glucose Oxidase biofuel cell by multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Lotfi, Ladan; Farahbakhsh, Afshin; Aghili, Sina

2018-01-01

Biofuel cells are a subset of fuel cells that employ biocatalysts. Enzyme-based biofuel cells (EBFCs) generate electrical energy from biofuels such as glucose and ethanol, which are renewable and sustainable energy sources. Glucose biofuel cells (GBFCs) are particularly interesting nowadays due to continuous harvesting of oxygen and glucose from bioavailable substrates, activity inside the human body, and environmental benign, which generate electricity through oxidation of glucose on the anode and reduction of oxygen on the cathode. Promoting the electron transfer of redox enzymes at modified electrode utilizing Nano size materials, such as carbon nanotubes (CNT), to achieve the direct electrochemistry of enzymes has been reported. The polypyrrole-MWCNTs-glucose oxidase (PY-CNT-GOx) electrode has been investigated in the present work. Cyclic voltammetry tests were performed in a three-electrode electrochemical set-up with modified electrode (Pt/PPy/MWCNTs/GOx) was used as working electrode. Platinum flat and Ag/AgCl (saturated KCl) were used as counter electrode and the reference electrode, respectively. The biofuel cells probe was prepared by immobilizing MWCNTs at the tip of a platinum (Pt) electrode (0.5 cm2) with PPy as the support matrix We have demonstrated a well-dispersed nanomaterial PPy/MWNT, which is able to immobilize GOx firmly under the condition of the absence of any other cross-linking agent.

Electroencephalogram measurement using polymer-based dry microneedle electrode

NASA Astrophysics Data System (ADS)

Arai, Miyako; Nishinaka, Yuya; Miki, Norihisa

2015-06-01

In this paper, we report a successful electroencephalogram (EEG) measurement using polymer-based dry microneedle electrodes. The electrodes consist of needle-shaped substrates of SU-8, a silver film, and a nanoporous parylene protective film. Differently from conventional wet electrodes, microneedle electrodes do not require skin preparation and a conductive gel. SU-8 is superior as a structural material to poly(dimethylsiloxane) (PDMS; Dow Corning Toray Sylgard 184) in terms of hardness, which was used in our previous work, and facilitates the penetration of needles through the stratum corneum. SU-8 microneedles can be successfully inserted into the skin without breaking and could maintain a sufficiently low skin-electrode contact impedance for EEG measurement. The electrodes successfully measured EEG from the frontal pole, and the quality of acquired signals was verified to be as high as those obtained using commercially available wet electrodes without any skin preparation or a conductive gel. The electrodes are readily applicable to record brain activities for a long period with little stress involved in skin preparation to the users.

Biomass-Derived Nitrogen-Doped Carbon Nanofiber Network: A Facile Template for Decoration of Ultrathin Nickel-Cobalt Layered Double Hydroxide Nanosheets as High-Performance Asymmetric Supercapacitor Electrode.

PubMed

Lai, Feili; Miao, Yue-E; Zuo, Lizeng; Lu, Hengyi; Huang, Yunpeng; Liu, Tianxi

2016-06-01

The development of biomass-based energy storage devices is an emerging trend to reduce the ever-increasing consumption of non-renewable resources. Here, nitrogen-doped carbonized bacterial cellulose (CBC-N) nanofibers are obtained by one-step carbonization of polyaniline coated bacterial cellulose (BC) nanofibers, which not only display excellent capacitive performance as the supercapacitor electrode, but also act as 3D bio-template for further deposition of ultrathin nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets. The as-obtained CBC-N@LDH composite electrodes exhibit significantly enhanced specific capacitance (1949.5 F g(-1) at a discharge current density of 1 A g(-1) , based on active materials), high capacitance retention of 54.7% even at a high discharge current density of 10 A g(-1) and excellent cycling stability of 74.4% retention after 5000 cycles. Furthermore, asymmetric supercapacitors (ASCs) are constructed using CBC-N@LDH composites as positive electrode materials and CBC-N nanofibers as negative electrode materials. By virtue of the intrinsic pseudocapacitive characteristics of CBC-N@LDH composites and 3D nitrogen-doped carbon nanofiber networks, the developed ASC exhibits high energy density of 36.3 Wh kg(-1) at the power density of 800.2 W kg(-1) . Therefore, this work presents a novel protocol for the large-scale production of biomass-derived high-performance electrode materials in practical supercapacitor applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancing capacitive deionization technology as an effective method for water treatment using commercially available graphene.

PubMed

Dursun, Derya; Ozkul, Selin; Yuksel, Recep; Unalan, Husnu Emrah

2017-02-01

In recent years, capacitive deionization (CDI) has been reported as one of the emerging technologies developed with the purpose of water desalination. This work is aimed at the integration of supercapacitor electrodes for efficient removal of ions from water, and thus to achieve an energy efficient, and cost-effective water treatment process. Our objective is to transfer the vast knowledge of supercapacitors and advanced materials in area of water treatment to enhance the knowledge of the CDI process. Towards the main purpose, graphene-based supercapacitor electrodes were developed from commercially available, cost-effective graphene and the use of these new materials for deionization was explored in detail. The porosity, morphology and electrochemical characteristics of the active materials were confirmed by Brunauer-Emmett-Teller method, scanning electron microscopy, Raman spectroscopy and chronoamperometry. Furthermore, the deionization performances of the graphene electrodes were evaluated by a laboratory scale CDI unit. The ion sorption behavior of the electrode was analyzed at different electrical potentials and flow rates. Impact of operating parameters on the sorption capacity was determined. At 20 mL/min flow rate and 2.0 V potential, the electrosorptive capacity of commercially available graphene electrodes could reach 12.5 μmol/g. Our results indicated the ability to use commercially available graphene for deionization purpose.

Field-Induced Alignment of Polar Bent-Ccore Smectic A Liquid Crystals

NASA Astrophysics Data System (ADS)

Shen, Yongqiang; Goodhew, Lisa; Shao, Renfan; Maclennan, Joseph; Clark, Noel; Rudquist, Per

2014-03-01

The SmAPF phase is a promising phase modulator mode. To use the SmAPF materials for applications, we need to obtain uniform, large-area alignment of the samples. However, bent-core liquid crystals are notoriously difficult to align with conventional surface treatment methods because most of them have no nematic phase. We have developed a powerful, new method using in-plane applied electric fields that allows us to create a perfect bookshelf alignment of orthogonal bent-core smectics. By using an interdigitated, finger-like electrode arrangement on one of the cell surfaces, we can align the materials by applying in-plane electric fields. This stripe geometry, which produces curved field lines, allows for only one smectic layer orientation, normal both to the cell walls and to the finger electrodes. After alignment, the cell can be operated in the conventional way by connecting the finger electrodes together to make one effective electrode, opposing continuous, common electrode on the opposite side of the cell. This alignment method opens up the use of these materials in perfectly aligned cells for both amplitude and phase-only modulation applications. This work was supported by NSF MRSEC Grant No. DMR-0820579, by NSF Grant No. DMR-1008300, and by Swedish Research Council (VR) Grant No. 621-2009-3621.

Freestanding hierarchically porous carbon framework decorated by polyaniline as binder-free electrodes for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Miao, Fujun; Shao, Changlu; Li, Xinghua; Wang, Kexin; Lu, Na; Liu, Yichun

2016-10-01

Freestanding hierarchically porous carbon electrode materials with favorable features of large surface areas, hierarchical porosity and continuous conducting pathways are very attractive for practical applications in electrochemical devices. Herein, three-dimensional freestanding hierarchically porous carbon (HPC) materials have been fabricated successfully mainly by the facile phase separation method. In order to further improve the energy storage ability, polyaniline (PANI) with high pseudocapacitance has been decorated on HPC through in situ chemical polymerization of aniline monomers. Benefiting from the synergistic effects between HPC and PANI, the resulting HPC/PANI composites as electrode materials present dramatic electrochemical performance with high specific capacitance up to 290 F g-1 at 0.5 A g-1 and good rate capability with ∼86% (248 F g-1) capacitance retention at 64 A g-1 of initial capacitance in three-electrode configuration. Moreover, the as-assembled symmetric supercapacitor based on HPC/PANI composites also demonstrates good capacitive properties with high energy density of 9.6 Wh kg-1 at 223 W kg-1 and long-term cycling stability with 78% capacitance retention after 10 000 cycles. Therefore, this work provides a new approach for designing high-performance electrodes with exceptional electrochemical performance, which are very promising for practical application in the energy storage field.

Short-range contacts govern the performance of industry-relevant battery cathodes

NASA Astrophysics Data System (ADS)

Morelly, Samantha L.; Alvarez, Nicolas J.; Tang, Maureen H.

2018-05-01

Fundamental understanding of how processing affects composite battery electrode structure and performance is still lacking, especially for industry-relevant electrodes with low fractions of inactive material. This work combines rheology, electronic conductivity measurements, and battery rate capability tests to prove that short-range electronic contacts are more important to cathode rate capability than either ion transport or long-range electronic conductivity. LiNi0.33Mn0.33Co0.33O2, carbon black, and polyvinylidene difluoride in 1-methyl-2-pyrrolidinone represent a typical commercial electrode with <5.5 wt% inactive material. Dry-mixing carbon black with active material decreases the relative fraction of bulk (free) carbon, as shown by small angle oscillatory shear and microscopy. More free carbon leads to a stronger gel network (more long-range particle contacts) and higher electronic conductivity of the dried films. Improvements in battery rate capability at constant electrode porosity do not correlate to electronic conductivity, but rather show an optimum fraction of free carbon. Simple comparison of rate capability in electrodes with increased total carbon loading (3 wt%) shows improvement for all fractions of free carbon. These results clearly indicate that ion transport cannot be limiting and highlight the critical importance of short-range electronic contacts for controlling battery performance.

Highly Flexible Freestanding Porous Carbon Nanofibers for Electrodes Materials of High-Performance All-Carbon Supercapacitors.

PubMed

Liu, Ying; Zhou, Jinyuan; Chen, Lulu; Zhang, Peng; Fu, Wenbin; Zhao, Hao; Ma, Yufang; Pan, Xiaojun; Zhang, Zhenxing; Han, Weihua; Xie, Erqing

2015-10-28

Highly flexible porous carbon nanofibers (P-CNFs) were fabricated by electrospining technique combining with metal ion-assistant acid corrosion process. The resultant fibers display high conductivity and outstanding mechanical flexibility, whereas little change in their resistance can be observed under repeatedly bending, even to 180°. Further results indicate that the improved flexibility of P-CNFs can be due to the high graphitization degree caused by Co ions. In view of electrode materials for high-performance supercapacitors, this type of porous nanostructure and high graphitization degree could synergistically facilitate the electrolyte ion diffusion and electron transportation. In the three electrodes testing system, the resultant P-CNFs electrodes can exhibit a specific capacitance of 104.5 F g(-1) (0.2 A g(-1)), high rate capability (remain 56.5% at 10 A g(-1)), and capacitance retention of ∼94% after 2000 cycles. Furthermore, the assembled symmetric supercapacitors showed a high flexibility and can deliver an energy density of 3.22 Wh kg(-1) at power density of 600 W kg(-1). This work might open a way to improve the mechanical properties of carbon fibers and suggests that this type of freestanding P-CNFs be used as effective electrode materials for flexible all-carbon supercapacitors.

Automatic control and detector for three-terminal resistance measurement

DOEpatents

Fasching, George E.

1976-10-26

A device is provided for automatic control and detection in a three-terminal resistance measuring instrument. The invention is useful for the rapid measurement of the resistivity of various bulk material with a three-terminal electrode system. The device maintains the current through the sample at a fixed level while measuring the voltage across the sample to detect the sample resistance. The three-electrode system contacts the bulk material and the current through the sample is held constant by means of a control circuit connected to a first of the three electrodes and works in conjunction with a feedback controlled amplifier to null the voltage between the first electrode and a second electrode connected to the controlled amplifier output. An A.C. oscillator provides a source of sinusoidal reference voltage of the frequency at which the measurement is to be executed. Synchronous reference pulses for synchronous detectors in the control circuit and an output detector circuit are provided by a synchronous pulse generator. The output of the controlled amplifier circuit is sampled by an output detector circuit to develop at an output terminal thereof a D.C. voltage which is proportional to the sample resistance R. The sample resistance is that segment of the sample between the area of the first electrode and the third electrode, which is connected to ground potential.

All Inkjet-Printed Amperometric Multiplexed Biosensors Based on Nanostructured Conductive Hydrogel Electrodes.

PubMed

Li, Lanlan; Pan, Lijia; Ma, Zhong; Yan, Ke; Cheng, Wen; Shi, Yi; Yu, Guihua

2018-06-13

Multiplexing, one of the main trends in biosensors, aims to detect several analytes simultaneously by integrating miniature sensors on a chip. However, precisely depositing electrode materials and selective enzymes on distinct microelectrode arrays remains an obstacle to massively produced multiplexed sensors. Here, we report on a "drop-on-demand" inkjet printing process to fabricate multiplexed biosensors based on nanostructured conductive hydrogels in which the electrode material and several kinds of enzymes were printed on the electrode arrays one by one by employing a multinozzle inkjet system. The whole inkjet printing process can be finished within three rounds of printing and only one round of alignment. For a page of sensor arrays containing 96 working electrodes, the printing process took merely ∼5 min. The multiplexed assays can detect glucose, lactate, and triglycerides in real time with good selectivity and high sensitivity, and the results in phosphate buffer solutions and calibration serum samples are comparable. The inkjet printing process exhibited advantages of high efficiency and accuracy, which opens substantial possibilities for massive fabrication of integrated multiplexed biosensors for human health monitoring.

Microengineered Conductive Elastomeric Electrodes for Long-Term Electrophysiological Measurements with Consistent Impedance under Stretch

PubMed Central

Hu, Dinglong; Cheng, Tin Kei; Xie, Kai; Lam, Raymond H. W.

2015-01-01

In this research, we develop a micro-engineered conductive elastomeric electrode for measurements of human bio-potentials with the absence of conductive pastes. Mixing the biocompatible polydimethylsiloxane (PDMS) silicone with other biocompatible conductive nano-particles further provides the material with an electrical conductivity. We apply micro-replica mold casting for the micro-structures, which are arrays of micro-pillars embedded between two bulk conductive-PDMS layers. These micro-structures can reduce the micro-structural deformations along the direction of signal transmission; therefore the corresponding electrical impedance under the physical stretch by the movement of the human body can be maintained. Additionally, we conduct experiments to compare the electrical properties between the bulk conductive-PDMS material and the microengineered electrodes under stretch. We also demonstrate the working performance of these micro-engineered electrodes in the acquisition of the 12-lead electrocardiographs (ECG) of a healthy subject. Together, the presented gel-less microengineered electrodes can provide a more convenient and stable bio-potential measurement platform, making tele-medical care more achievable with reduced technical barriers for instrument installation performed by patients/users themselves. PMID:26512662

Electrostatic atomization: Effect of electrode materials on electrostatic atomizer performance

NASA Astrophysics Data System (ADS)

Sankaran, Abhilash; Staszel, Christopher; Kashir, Babak; Perri, Anthony; Mashayek, Farzad; Yarin, Alexander

2016-11-01

Electrostatic atomization was studied experimentally with a pointed electrode in a converging nozzle. Experiments were carried out on poorly conductive canola oil where it was observed that electrode material may affect charge transfer. This points at the possible faradaic reactions that can occur at the surfaces of the electrodes. The supply voltage is applied to the sharp electrode and the grounded nozzle body constitutes the counter-electrode. The charge transfer is controlled by the electrochemical reactions on both the electrodes. The electrical performance study of the atomizer issuing a charged oil jet was conducted using three different nozzle body materials - brass, copper and stainless steel. Also, two sharp electrode materials - brass and stainless steel - were tested. The experimental results revealed that both the nozzle body material, as well as the sharp electrode material affected the spray and leak currents. Moreover, the effect of the sharp electrode material is quite significant. This research is supported by NSF Grant 1505276.

Highly ordered mesoporous carbons as electrode material for the construction of electrochemical dehydrogenase- and oxidase-based biosensors.

PubMed

Zhou, Ming; Shang, Li; Li, Bingling; Huang, Lijian; Dong, Shaojun

2008-11-15

In this work, the excellent catalytic activity of highly ordered mesoporous carbons (OMCs) to the electrooxidation of nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H(2)O(2)) was described for the construction of electrochemical alcohol dehydrogenase (ADH) and glucose oxidase (GOD)-based biosensors. The high density of edge-plane-like defective sites and high specific surface area of OMCs could be responsible for the electrocatalytic behavior at OMCs modified glassy carbon electrode (OMCs/GE), which induced a substantial decrease in the overpotential of NADH and H(2)O(2) oxidation reaction compared to carbon nanotubes modified glassy carbon electrode (CNTs/GE). Such ability of OMCs permits effective low-potential amperometric biosensing of ethanol and glucose, respectively, at Nafion/ADH-OMCs/GE and Nafion/GOD-OMCs/GE. Especially, as an amperometric glucose biosensor, Nafion/GOD-OMCs/GE showed large determination range (500-15,000 micromoll(-1)), high sensitivity (0.053 nA micromol(-1)), fast (9+/-1s) and stable response (amperometric response retained 90% of the initial activity after 10h stirring of 2 mmoll(-1) glucose solution) to glucose as well as the effective discrimination to the possible interferences, which may make it to readily satisfy the need for the routine clinical diagnosis of diabetes. By comparing the electrochemical performance of OMCs with that of CNTs as electrode material for the construction of ADH- and GOD-biosensors in this work, we reveal that OMCs could be a favorable and promising carbon electrode material for constructing other electrochemical dehydrogenase- and oxidase-based biosensors, which may have wide potential applications in biocatalysis, bioelectronics and biofuel cells.

Metal electrode for amorphous silicon solar cells

DOEpatents

Williams, Richard

1983-01-01

An amorphous silicon solar cell having an N-type region wherein the contact to the N-type region is composed of a material having a work function of about 3.7 electron volts or less. Suitable materials include strontium, barium and magnesium and rare earth metals such as gadolinium and yttrium.

Carbon Quantum Dot Surface-Engineered VO2 Interwoven Nanowires: A Flexible Cathode Material for Lithium and Sodium Ion Batteries.

PubMed

Balogun, Muhammad-Sadeeq; Luo, Yang; Lyu, Feiyi; Wang, Fuxin; Yang, Hao; Li, Haibo; Liang, Chaolun; Huang, Miao; Huang, Yongchao; Tong, Yexiang

2016-04-20

The use of electrode materials in their powdery form requires binders and conductive additives for the fabrication of the cells, which leads to unsatisfactory energy storage performance. Recently, a new strategy to design flexible, binder-, and additive-free three-dimensional electrodes with nanoscale surface engineering has been exploited in boosting the storage performance of electrode materials. In this paper, we design a new type of free-standing carbon quantum dot coated VO2 interwoven nanowires through a simple fabrication process and demonstrate its potential to be used as cathode material for lithium and sodium ion batteries. The versatile carbon quantum dots that are vastly flexible for surface engineering serve the function of protecting the nanowire surface and play an important role in the diffusion of electrons. Also, the three-dimensional carbon cloth coated with VO2 interwoven nanowires assisted in the diffusion of ions through the inner and the outer surface. With this unique architecture, the carbon quantum dot nanosurface engineered VO2 electrode exhibited capacities of 420 and 328 mAh g(-1) at current density rate of 0.3 C for lithium and sodium storage, respectively. This work serves as a milestone for the potential replacement of lithium ion batteries and next generation postbatteries.

Electrochemical Ultracapacitors Using Graphitic Nanostacks

NASA Technical Reports Server (NTRS)

Marotta, Christopher

2012-01-01

Electrochemical ultracapacitors (ECs) have been developed using graphitic nanostacks as the electrode material. The advantages of this technology will be the reduction of device size due to superior power densities and relative powers compared to traditional activated carbon electrodes. External testing showed that these materials display reduced discharge response times compared to state-of-the-art materials. Such applications are advantageous for pulsed power applications such as burst communications (satellites, cell phones), electromechanical actuators, and battery load leveling in electric vehicles. These carbon nanostructures are highly conductive and offer an ordered mesopore network. These attributes will provide more complete electrolyte wetting, and faster release of stored charge compared to activated carbon. Electrochemical capacitor (EC) electrode materials were developed using commercially available nanomaterials and modifying them to exploit their energy storage properties. These materials would be an improvement over current ECs that employ activated carbon as the electrode material. Commercially available graphite nanofibers (GNFs) are used as precursor materials for the synthesis of graphitic nanostacks (GNSs). These materials offer much greater surface area than graphite flakes. Additionally, these materials offer a superior electrical conductivity and a greater average pore size compared to activated carbon electrodes. The state of the art in EC development uses activated carbon (AC) as the electrode material. AC has a high surface area, but its small average pore size inhibits electrolyte ingress/egress. Additionally, AC has a higher resistivity, which generates parasitic heating in high-power applications. This work focuses on fabricating EC from carbon that has a very different structure by increasing the surface area of the GNF by intercalation or exfoliation of the graphitic basal planes. Additionally, various functionalities to the GNS surface will be added that can exhibit pseudocapacitance. This pseudocapacitance exhibits faradaic (charge transfer) properties that can further increase the overall relative and volumetric capacitance of the material. A process is also proposed to use GNF as a precursor material to fabricate GNS that will be used as EC electrodes. This results in much better electrical conductivity than activated carbon. This is advantageous for high-pulsed-power applications to reduce parasitic heating. Larger average pore size allows more complete electrolyte wetting (faster charge transfer kinetics). These properties contribute to a lowered equivalent series resistance (ESR), increased specific power, shorter charging times, and decreased parasitic heating. The high density of basal plane edges provides nucleation sites for activation (addition of hydrophilic functional groups) that facilitate electrolyte wetting, and will contribute to pseudocapacitance.

Electrochemical cell

DOEpatents

Nagy, Z.; Yonco, R.M.; You, H.; Melendres, C.A.

1992-08-25

An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90[degree] in either direction while maintaining the working and counter electrodes submerged in the electrolyte. 5 figs.

Electrochemical cell

DOEpatents

Nagy, Zoltan; Yonco, Robert M.; You, Hoydoo; Melendres, Carlos A.

1992-01-01

An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90.degree. in either direction while maintaining the working and counter electrodes submerged in the electrolyte.

Highly conductive porous Na-embedded carbon nanowalls for high-performance capacitive deionization

NASA Astrophysics Data System (ADS)

Chang, Liang; Hu, Yun Hang

2018-05-01

Highly conductive porous Na-embedded carbon nanowalls (Na@C), which were recently invented, have exhibited excellent performance for dye-sensitized solar cells and electric double-layer capacitors. In this work, Na@C was demonstrated as an excellent electrode material for capacitive deionization (CDI). In a three-electrode configuration system, the specific capacity of the Na@C electrodes can achieve 306.4 F/g at current density of 0.2 A/g in 1 M NaCl, which is higher than that (235.2 F/g) of activated carbon (AC) electrodes. Furthermore, a high electrosorption capacity of 8.75 mg g-1 in 100 mg/L NaCl was obtained with the Na@C electrodes in a batch-mode capacitive deionization cell. It exceeds the electrosorption capacity (4.08 mg g-1) of AC electrodes. The Na@C electrode also showed a promising cycle stability. The excellent performance of Na@C electrode for capacitive deionization (CDI) can be attributed to its high electrical conductivity and large accessible surface area.

Electrode Materials, Electrolytes, and Challenges in Nonaqueous Lithium-Ion Capacitors.

PubMed

Li, Bing; Zheng, Junsheng; Zhang, Hongyou; Jin, Liming; Yang, Daijun; Lv, Hong; Shen, Chao; Shellikeri, Annadanesh; Zheng, Yiran; Gong, Ruiqi; Zheng, Jim P; Zhang, Cunman

2018-04-01

Among the various energy-storage systems, lithium-ion capacitors (LICs) are receiving intensive attention due to their high energy density, high power density, long lifetime, and good stability. As a hybrid of lithium-ion batteries and supercapacitors, LICs are composed of a battery-type electrode and a capacitor-type electrode and can potentially combine the advantages of the high energy density of batteries and the large power density of capacitors. Here, the working principle of LICs is discussed, and the recent advances in LIC electrode materials, particularly activated carbon and lithium titanate, as well as in electrolyte development are reviewed. The charge-storage mechanisms for intercalative pseudocapacitive behavior, battery behavior, and conventional pseudocapacitive behavior are classified and compared. Finally, the prospects and challenges associated with LICs are discussed. The overall aim is to provide deep insights into the LIC field for continuing research and development of second-generation energy-storage technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Galvanostatic Intermittent Titration and Performance Based Analysis of LiNi 0.5 Co 0.2 Mn 0.3 O 2 Cathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Ankit; Smith, Kandler; Santhanagopalan, Shriram

Galvanostatic intermittent titration technique (GITT) - a popular method for characterizing kinetic and transport properties of battery electrodes - is predicated on the proper evaluation of electrode active area. LiNi 0.5044Co 0.1986Mn 0.2970O 2 (NCM523) material exhibits a complex morphology in which sub-micron primary particles aggregate to form secondary particle agglomerates. Our work proposes a new active area formulation for primary/secondary particle agglomerate materials to better mimic the morphology of NCM532 electrodes. Furthermore, this formulation is then coupled with macro-homogeneous models to simulate GITT and half-cell performance of NCM523 electrodes. Subsequently, the model results are compared against the experimental resultsmore » to refine the area formulation. A single parameter, the surface roughness factor, is proposed to mimic the change in interfacial area, diffusivity and exchange current density simultaneously and detailed modeling results are presented to provide valuable insights into the efficacy of the formulation.« less

Galvanostatic Intermittent Titration and Performance Based Analysis of LiNi 0.5Co 0.2 Mn 0.3O 2Cathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Ankit; Smith, Kandler; Santhanagopalan, Shriram

Galvanostatic intermittent titration technique (GITT) – a popular method for characterizing kinetic and transport properties of battery electrodes – is predicated on the proper evaluation of electrode active area. LiNi0.5044Co0.1986Mn0.2970O2 (NCM523) material exhibits a complex morphology in which sub-micron primary particles aggregate to form secondary particle agglomerates. This work proposes a new active area formulation for primary/secondary particle agglomerate materials to better mimic the morphology of NCM532 electrodes. This formulation is then coupled with macro-homogeneous models to simulate GITT and half-cell performance of NCM523 electrodes. Subsequently, the model results are compared against the experimental results to refine the area formulation.more » A single parameter, the surface roughness factor, is proposed to mimic the change in interfacial area, diffusivity and exchange current density simultaneously and detailed modeling results are presented to provide valuable insights into the efficacy of the formulation.« less

Screen-Printed Electrodes Modified with “Green” Metals for Electrochemical Stripping Analysis of Toxic Elements

PubMed Central

Economou, Anastasios

2018-01-01

This work reviews the field of screen-printed electrodes (SPEs) modified with “green” metals for electrochemical stripping analysis of toxic elements. Electrochemical stripping analysis has been established as a useful trace analysis technique offering many advantages compared to competing optical techniques. Although mercury has been the preferred electrode material for stripping analysis, the toxicity of mercury and the associated legal requirements in its use and disposal have prompted research towards the development of “green” metals as alternative electrode materials. When combined with the screen-printing technology, such environment-friendly metals can lead to disposable sensors for trace metal analysis with excellent operational characteristics. This review focuses on SPEs modified with Au, Bi, Sb, and Sn for stripping analysis of toxic elements. Different modification approaches (electroplating, bulk modification, use of metal precursors, microengineering techniques) are considered and representative applications are described. A developing related field, namely biosensing based on stripping analysis of metallic nanoprobe labels, is also briefly mentioned. PMID:29596391

Screen-Printed Electrodes Modified with "Green" Metals for Electrochemical Stripping Analysis of Toxic Elements.

PubMed

Economou, Anastasios

2018-03-29

This work reviews the field of screen-printed electrodes (SPEs) modified with "green" metals for electrochemical stripping analysis of toxic elements. Electrochemical stripping analysis has been established as a useful trace analysis technique offering many advantages compared to competing optical techniques. Although mercury has been the preferred electrode material for stripping analysis, the toxicity of mercury and the associated legal requirements in its use and disposal have prompted research towards the development of "green" metals as alternative electrode materials. When combined with the screen-printing technology, such environment-friendly metals can lead to disposable sensors for trace metal analysis with excellent operational characteristics. This review focuses on SPEs modified with Au, Bi, Sb, and Sn for stripping analysis of toxic elements. Different modification approaches (electroplating, bulk modification, use of metal precursors, microengineering techniques) are considered and representative applications are described. A developing related field, namely biosensing based on stripping analysis of metallic nanoprobe labels, is also briefly mentioned.

Engineering Redox Potential of Lithium Clusters for Electrode Material in Lithium-Ion Batteries

DOE PAGES

Kushwaha, Anoop Kumar; Sahoo, Mihir Ranjan; Nanda, Jagjit; ...

2017-07-01

Low negative electrode potential and high reactivity makes lithium (Li) ideal candidate for obtaining highest possible energy density among other materials. Here, we show a novel route with which the overall electrode potential could significantly be enhanced through selection of cluster size. In using first principles density functional theory and continuum dielectric model, we studied free energy and redox potential as well as investigated relative stability of Li n (n ≤ 8) clusters in both gas phase and solution. We found that Li 3 has the lowest negative redox potential (thereby highest overall electrode potential) suggesting that cluster based approachmore » could provide a novel way of engineering the next generation battery technology. The microscopic origin of Li 3 cluster’s superior performance is related to two major factors: gas phase ionization and difference between solvation free energy for neutral and positive ion. Taken together, our study provides insight into the engineering of redox potential in battery and could stimulate further work in this direction.« less

High-Performance Supercapacitor Electrode Materials from Cellulose-Derived Carbon Nanofibers.

PubMed

Cai, Jie; Niu, Haitao; Li, Zhenyu; Du, Yong; Cizek, Pavel; Xie, Zongli; Xiong, Hanguo; Lin, Tong

2015-07-15

Nitrogen-functionalized carbon nanofibers (N-CNFs) were prepared by carbonizing polypyrrole (PPy)-coated cellulose NFs, which were obtained by electrospinning, deacetylation of electrospun cellulose acetate NFs, and PPy polymerization. Supercapacitor electrodes prepared from N-CNFs and a mixture of N-CNFs and Ni(OH)2 showed specific capacitances of ∼236 and ∼1045 F g(-1), respectively. An asymmetric supercapacitor was further fabricated using N-CNFs/Ni(OH)2 and N-CNFs as positive and negative electrodes. The supercapacitor device had a working voltage of 1.6 V in aqueous KOH solution (6.0 M) with an energy density as high as ∼51 (W h) kg(-1) and a maximum power density of ∼117 kW kg(-1). The device had excellent cycle lifetime, which retained ∼84% specific capacitance after 5000 cycles of cyclic voltammetry scans. N-CNFs derived from electrospun cellulose may be useful as an electrode material for development of high-performance supercapacitors and other energy storage devices.

Engineering Redox Potential of Lithium Clusters for Electrode Material in Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kushwaha, Anoop Kumar; Sahoo, Mihir Ranjan; Nanda, Jagjit

Low negative electrode potential and high reactivity makes lithium (Li) ideal candidate for obtaining highest possible energy density among other materials. Here, we show a novel route with which the overall electrode potential could significantly be enhanced through selection of cluster size. In using first principles density functional theory and continuum dielectric model, we studied free energy and redox potential as well as investigated relative stability of Li n (n ≤ 8) clusters in both gas phase and solution. We found that Li 3 has the lowest negative redox potential (thereby highest overall electrode potential) suggesting that cluster based approachmore » could provide a novel way of engineering the next generation battery technology. The microscopic origin of Li 3 cluster’s superior performance is related to two major factors: gas phase ionization and difference between solvation free energy for neutral and positive ion. Taken together, our study provides insight into the engineering of redox potential in battery and could stimulate further work in this direction.« less

Galvanostatic Intermittent Titration and Performance Based Analysis of LiNi 0.5 Co 0.2 Mn 0.3 O 2 Cathode

DOE PAGES

Verma, Ankit; Smith, Kandler; Santhanagopalan, Shriram; ...

2017-11-03

Galvanostatic intermittent titration technique (GITT) - a popular method for characterizing kinetic and transport properties of battery electrodes - is predicated on the proper evaluation of electrode active area. LiNi 0.5044Co 0.1986Mn 0.2970O 2 (NCM523) material exhibits a complex morphology in which sub-micron primary particles aggregate to form secondary particle agglomerates. Our work proposes a new active area formulation for primary/secondary particle agglomerate materials to better mimic the morphology of NCM532 electrodes. Furthermore, this formulation is then coupled with macro-homogeneous models to simulate GITT and half-cell performance of NCM523 electrodes. Subsequently, the model results are compared against the experimental resultsmore » to refine the area formulation. A single parameter, the surface roughness factor, is proposed to mimic the change in interfacial area, diffusivity and exchange current density simultaneously and detailed modeling results are presented to provide valuable insights into the efficacy of the formulation.« less

Factors that Influence RF Breakdown in Antenna Systems

NASA Astrophysics Data System (ADS)

Caughman, J. B. O.; Baity, F. W.; Rasmussen, D. A.; Aghazarian, M.; Castano Giraldo, C. H.; Ruzic, David

2007-11-01

One of the main power-limiting factors in antenna systems is the maximum voltage that the antenna or vacuum transmission line can sustain before breaking down. The factors that influence RF breakdown are being studied in a resonant 1/4-wavelength section of vacuum transmission line terminated with an open circuit electrode structure. Breakdown can be initiated via electron emission by high electric fields and by plasma formation in the structure, depending on the gas pressure. Recent experiments have shown that a 1 kG magnetic field can influence plasma formation at pressures as low as 8x10-5 Torr at moderate voltage levels (<5 kV). Ultraviolet light, with energies near the work function of the electrode material, can induce a multipactor discharge and limit power transmission. Details of these experimental results, including the effect of electrode materials (Ni and Cu), will be presented. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725. Work supported by USDOE with grant DE-FG02-04ER54765

Study on effect of tool electrodes on surface finish during electrical discharge machining of Nitinol

NASA Astrophysics Data System (ADS)

Sahu, Anshuman Kumar; Chatterjee, Suman; Nayak, Praveen Kumar; Sankar Mahapatra, Siba

2018-03-01

Electrical discharge machining (EDM) is a non-traditional machining process which is widely used in machining of difficult-to-machine materials. EDM process can produce complex and intrinsic shaped component made of difficult-to-machine materials, largely applied in aerospace, biomedical, die and mold making industries. To meet the required applications, the EDMed components need to possess high accuracy and excellent surface finish. In this work, EDM process is performed using Nitinol as work piece material and AlSiMg prepared by selective laser sintering (SLS) as tool electrode along with conventional copper and graphite electrodes. The SLS is a rapid prototyping (RP) method to produce complex metallic parts by additive manufacturing (AM) process. Experiments have been carried out varying different process parameters like open circuit voltage (V), discharge current (Ip), duty cycle (τ), pulse-on-time (Ton) and tool material. The surface roughness parameter like average roughness (Ra), maximum height of the profile (Rt) and average height of the profile (Rz) are measured using surface roughness measuring instrument (Talysurf). To reduce the number of experiments, design of experiment (DOE) approach like Taguchi’s L27 orthogonal array has been chosen. The surface properties of the EDM specimen are optimized by desirability function approach and the best parametric setting is reported for the EDM process. Type of tool happens to be the most significant parameter followed by interaction of tool type and duty cycle, duty cycle, discharge current and voltage. Better surface finish of EDMed specimen can be obtained with low value of voltage (V), discharge current (Ip), duty cycle (τ) and pulse on time (Ton) along with the use of AlSiMg RP electrode.

Supercapacitors specialities - Materials review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Obreja, Vasile V. N.

The electrode material is a key component for supercapacitor cell performance. As it is known, performance comparison of commercial available batteries and supercapacitors reveals significantly lower energy storage capability for supercapacitor devices. The energy density of commercial supercapacitor cells is limited to 10 Wh/kg whereas that of common lead acid batteries reaches 35-40 Wh/kg. For lithium ion batteries a value higher than 100 Wh/kg is easily available. Nevertheless, supercapacitors also known as ultracapacitors or electrochemical capacitors have other advantages in comparison with batteries. As a consequence, many efforts have been made in the last years to increase the storage energymore » density of electrochemical capacitors. A lot of results from published work (research and review papers, patents and reports) are available at this time. The purpose of this review is a presentation of the progress to date for the use of new materials and approaches for supercapacitor electrodes, with focus on the energy storage capability for practical applications. Many reported results refer to nanostructured carbon based materials and the related composites, used for the manufacture of experimental electrodes. A specific capacitance and a specific energy are seldom revealed as the main result of the performed investigation. Thus for nanoprous (activated) carbon based electrodes a specific capacitance up to 200-220 F/g is mentioned for organic electrolyte, whereas for aqueous electrolyte, the value is limited to 400-500 F/g. Significant contribution to specific capacitance is possible from fast faradaic reactions at the electrode-electrolyte interface in addition to the electric double layer effect. The corresponding energy density is limited to 30-50 Wh/kg for organic electrolyte and to 12-17 Wh/kg for aqueous electrolyte. However such performance indicators are given only for the carbon material used in electrodes. For a supercapacitor cell, where two electrodes and also other materials for cell assembling and packaging are used, the above mentioned values have to be divided by a factor higher than four. As a consequence, the specific energy of a prototype cell, hardly could exceed 10 Wh/kg because of difficulties with the existing manufacturing technology. Graphene based materials and carbon nanotubes and different composites have been used in many experiments reported in the last years. Nevertheless in spite of the outstanding properties of these materials, significant increase of the specific capacitance or of the specific energy in comparison with activated or nanoporous carbon is not achieved. Use of redox materials as metal oxides or conducting polymers in combination with different nanostructured carbon materials (nanocomposite electrodes) has been found to contribute to further increase of the specific capacitance or of the specific energy. Nevertheless, few results are reported for practical cells with such materials. Many results are reported only for a three electrode system and significant difference is possible when the electrode is used in a practical supercapacitor cell. Further improvement in the electrode manufacture and more experiments with supercapacitor cells with the known electrochemical storage materials are required. Device prototypes and commercial products with an energy density towards 15-20 Wh/kg could be realized. These may be a milestone for further supercapacitor device research and development, to narrow the storage energy gap between batteries and supercapacitors.« less

Supercapacitors specialities - Materials review

NASA Astrophysics Data System (ADS)

Obreja, Vasile V. N.

2014-06-01

The electrode material is a key component for supercapacitor cell performance. As it is known, performance comparison of commercial available batteries and supercapacitors reveals significantly lower energy storage capability for supercapacitor devices. The energy density of commercial supercapacitor cells is limited to 10 Wh/kg whereas that of common lead acid batteries reaches 35-40 Wh/kg. For lithium ion batteries a value higher than 100 Wh/kg is easily available. Nevertheless, supercapacitors also known as ultracapacitors or electrochemical capacitors have other advantages in comparison with batteries. As a consequence, many efforts have been made in the last years to increase the storage energy density of electrochemical capacitors. A lot of results from published work (research and review papers, patents and reports) are available at this time. The purpose of this review is a presentation of the progress to date for the use of new materials and approaches for supercapacitor electrodes, with focus on the energy storage capability for practical applications. Many reported results refer to nanostructured carbon based materials and the related composites, used for the manufacture of experimental electrodes. A specific capacitance and a specific energy are seldom revealed as the main result of the performed investigation. Thus for nanoprous (activated) carbon based electrodes a specific capacitance up to 200-220 F/g is mentioned for organic electrolyte, whereas for aqueous electrolyte, the value is limited to 400-500 F/g. Significant contribution to specific capacitance is possible from fast faradaic reactions at the electrode-electrolyte interface in addition to the electric double layer effect. The corresponding energy density is limited to 30-50 Wh/kg for organic electrolyte and to 12-17 Wh/kg for aqueous electrolyte. However such performance indicators are given only for the carbon material used in electrodes. For a supercapacitor cell, where two electrodes and also other materials for cell assembling and packaging are used, the above mentioned values have to be divided by a factor higher than four. As a consequence, the specific energy of a prototype cell, hardly could exceed 10 Wh/kg because of difficulties with the existing manufacturing technology. Graphene based materials and carbon nanotubes and different composites have been used in many experiments reported in the last years. Nevertheless in spite of the outstanding properties of these materials, significant increase of the specific capacitance or of the specific energy in comparison with activated or nanoporous carbon is not achieved. Use of redox materials as metal oxides or conducting polymers in combination with different nanostructured carbon materials (nanocomposite electrodes) has been found to contribute to further increase of the specific capacitance or of the specific energy. Nevertheless, few results are reported for practical cells with such materials. Many results are reported only for a three electrode system and significant difference is possible when the electrode is used in a practical supercapacitor cell. Further improvement in the electrode manufacture and more experiments with supercapacitor cells with the known electrochemical storage materials are required. Device prototypes and commercial products with an energy density towards 15-20 Wh/kg could be realized. These may be a milestone for further supercapacitor device research and development, to narrow the storage energy gap between batteries and supercapacitors.

Electro-optic device with gap-coupled electrode

DOEpatents

Deri, Robert J.; Rhodes, Mark A.; Bayramian, Andrew J.; Caird, John A.; Henesian, Mark A.; Ebbers, Christopher A.

2013-08-20

An electro-optic device includes an electro-optic crystal having a predetermined thickness, a first face and a second face. The electro-optic device also includes a first electrode substrate disposed opposing the first face. The first electrode substrate includes a first substrate material having a first thickness and a first electrode coating coupled to the first substrate material. The electro-optic device further includes a second electrode substrate disposed opposing the second face. The second electrode substrate includes a second substrate material having a second thickness and a second electrode coating coupled to the second substrate material. The electro-optic device additionally includes a voltage source electrically coupled to the first electrode coating and the second electrode coating.

Inductive dielectric analyzer

NASA Astrophysics Data System (ADS)

Agranovich, Daniel; Polygalov, Eugene; Popov, Ivan; Ben Ishai, Paul; Feldman, Yuri

2017-03-01

One of the approaches to bypass the problem of electrode polarization in dielectric measurements is the free electrode method. The advantage of this technique is that, the probing electric field in the material is not supplied by contact electrodes, but rather by electromagnetic induction. We have designed an inductive dielectric analyzer based on a sensor comprising two concentric toroidal coils. In this work, we present an analytic derivation of the relationship between the impedance measured by the sensor and the complex dielectric permittivity of the sample. The obtained relationship was successfully employed to measure the dielectric permittivity and conductivity of various alcohols and aqueous salt solutions.

Emerging Prototype Sodium-Ion Full Cells with Nanostructured Electrode Materials.

PubMed

Ren, Wenhao; Zhu, Zixuan; An, Qinyou; Mai, Liqiang

2017-06-01

Due to steadily increasing energy consumption, the demand of renewable energy sources is more urgent than ever. Sodium-ion batteries (SIBs) have emerged as a cost-effective alternative because of the earth abundance of Na resources and their competitive electrochemical behaviors. Before practical application, it is essential to establish a bridge between the sodium half-cell and the commercial battery from a full cell perspective. An overview of the major challenges, most recent advances, and outlooks of non-aqueous and aqueous sodium-ion full cells (SIFCs) is presented. Considering the intimate relationship between SIFCs and electrode materials, including structure, composition and mutual matching principle, both the advance of various prototype SIFCs and the electrochemistry development of nanostructured electrode materials are reviewed. It is noted that a series of SIFCs combined with layered oxides and hard carbon are capable of providing a high specific gravimetric energy above 200 Wh kg -1 , and an NaCrO 2 //hard carbon full cell is able to deliver a high rate capability over 100 C. To achieve industrialization of SIBs, more systematic work should focus on electrode construction, component compatibility, and battery technologies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

PubMed Central

Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

2013-01-01

Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10–40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage. PMID:24145684

Asymmetric supercapacitors utilizing highly porous metal-organic framework derived Co3O4 nanosheets grown on Ni foam and polyaniline hydrogel derived N-doped nanocarbon electrode materials

NASA Astrophysics Data System (ADS)

Fan, Xin; Chen, Weiliang; Pang, Shuhua; Lu, Wei; Zhao, Yu; Liu, Zheng; Fang, Dong

2017-12-01

In the present work, asymmetric supercapacitors (ASCs) are assembled using a highly conductive N-doped nanocarbon (NDC) material derived from a polyaniline hydrogel as a cathode, and Ni foam covered with flower-like Co3O4 nanosheets (Co3O4-Ni) prepared from a zeolitic imidazolate metal-organic framework as a single precursor serves as a high gravimetric capacitance anode. At a current of 0.2 A g-1, the Co3O4-Ni electrode provides a gravimetric capacitance of 637.7 F g-1, and the NDC electrode provides a gravimetric capacitance of 359.6 F g-1. The ASC assembled with an optimal active material loading operates within a wide potential window of 0-1.1 V, and provides a high areal capacitance of 25.7 mF cm-2. The proposed ASC represents a promising strategy for designing high-performance supercapacitors.

Surface engineered porous silicon for stable, high performance electrochemical supercapacitors.

PubMed

Oakes, Landon; Westover, Andrew; Mares, Jeremy W; Chatterjee, Shahana; Erwin, William R; Bardhan, Rizia; Weiss, Sharon M; Pint, Cary L

2013-10-22

Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10-40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage.

Surface engineered porous silicon for stable, high performance electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Oakes, Landon; Westover, Andrew; Mares, Jeremy W.; Chatterjee, Shahana; Erwin, William R.; Bardhan, Rizia; Weiss, Sharon M.; Pint, Cary L.

2013-10-01

Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped silicon materials boast a low mass density, excellent conductivity, a controllably etched nanoporous structure, and combined earth abundance and technological presence appealing to diverse energy storage frameworks. Here, we demonstrate a universal route to transform porous silicon (P-Si) into stable electrodes for electrochemical devices through growth of an ultra-thin, conformal graphene coating on the P-Si surface. This graphene coating simultaneously passivates surface charge traps and provides an ideal electrode-electrolyte electrochemical interface. This leads to 10-40X improvement in energy density, and a 2X wider electrochemical window compared to identically-structured unpassivated P-Si. This work demonstrates a technique generalizable to mesoporous and nanoporous materials that decouples the engineering of electrode structure and electrochemical surface stability to engineer performance in electrochemical environments. Specifically, we demonstrate P-Si as a promising new platform for grid-scale and integrated electrochemical energy storage.

Nanostructured carbon and carbon nanocomposites for electrochemical energy storage applications.

PubMed

Su, Dang Sheng; Schlögl, Robert

2010-02-22

Electrochemical energy storage is one of the important technologies for a sustainable future of our society, in times of energy crisis. Lithium-ion batteries and supercapacitors with their high energy or power densities, portability, and promising cycling life are the cores of future technologies. This Review describes some materials science aspects on nanocarbon-based materials for these applications. Nanostructuring (decreasing dimensions) and nanoarchitecturing (combining or assembling several nanometer-scale building blocks) are landmarks in the development of high-performance electrodes for with long cycle lifes and high safety. Numerous works reviewed herein have shown higher performances for such electrodes, but mostly give diverse values that show no converging tendency towards future development. The lack of knowledge about interface processes and defect dynamics of electrodes, as well as the missing cooperation between material scientists, electrochemists, and battery engineers, are reasons for the currently widespread trial-and-error strategy of experiments. A concerted action between all of these disciplines is a prerequisite for the future development of electrochemical energy storage devices.

Fully Packaged Carbon Nanotube Supercapacitors by Direct Ink Writing on Flexible Substrates.

PubMed

Chen, Bolin; Jiang, Yizhou; Tang, Xiaohui; Pan, Yayue; Hu, Shan

2017-08-30

The ability to print fully packaged integrated energy storage components (e.g., supercapacitors) is of critical importance for practical applications of printed electronics. Due to the limited variety of printable materials, most studies on printed supercapacitors focus on printing the electrode materials but rarely the full-packaged cell. This work presents for the first time the printing of a fully packaged single-wall carbon nanotube-based supercapacitor with direct ink writing (DIW) technology. Enabled by the developed ink formula, DIW setup, and cell architecture, the whole printing process is mask free, transfer free, and alignment free with precise and repeatable control on the spatial distribution of all constituent materials. Studies on cell design show that a wider electrode pattern and narrower gap distance between electrodes lead to higher specific capacitance. The as-printed fully packaged supercapacitors have energy and power performances that are among the best in recently reported planar carbon-based supercapacitors that are only partially printed or nonprinted.

A 3D Microfluidic Chip for Electrochemical Detection of Hydrolysed Nucleic Bases by a Modified Glassy Carbon Electrode

PubMed Central

Vlachova, Jana; Tmejova, Katerina; Kopel, Pavel; Korabik, Maria; Zitka, Jan; Hynek, David; Kynicky, Jindrich; Adam, Vojtech; Kizek, Rene

2015-01-01

Modification of carbon materials, especially graphene-based materials, has wide applications in electrochemical detection such as electrochemical lab-on-chip devices. A glassy carbon electrode (GCE) modified with chemically alternated graphene oxide was used as a working electrode (glassy carbon modified by graphene oxide with sulphur containing compounds and Nafion) for detection of nucleobases in hydrolysed samples (HCl pH = 2.9, 100 °C, 1 h, neutralization by NaOH). It was found out that modification, especially with trithiocyanuric acid, increased the sensitivity of detection in comparison with pure GCE. All processes were finally implemented in a microfluidic chip formed with a 3D printer by fused deposition modelling technology. As a material for chip fabrication, acrylonitrile butadiene styrene was chosen because of its mechanical and chemical stability. The chip contained the one chamber for the hydrolysis of the nucleic acid and another for the electrochemical detection by the modified GCE. This chamber was fabricated to allow for replacement of the GCE. PMID:25621613

A 3D microfluidic chip for electrochemical detection of hydrolysed nucleic bases by a modified glassy carbon electrode.

PubMed

Vlachova, Jana; Tmejova, Katerina; Kopel, Pavel; Korabik, Maria; Zitka, Jan; Hynek, David; Kynicky, Jindrich; Adam, Vojtech; Kizek, Rene

2015-01-22

Modification of carbon materials, especially graphene-based materials, has wide applications in electrochemical detection such as electrochemical lab-on-chip devices. A glassy carbon electrode (GCE) modified with chemically alternated graphene oxide was used as a working electrode (glassy carbon modified by graphene oxide with sulphur containing compounds and Nafion) for detection of nucleobases in hydrolysed samples (HCl pH = 2.9, 100 °C, 1 h, neutralization by NaOH). It was found out that modification, especially with trithiocyanuric acid, increased the sensitivity of detection in comparison with pure GCE. All processes were finally implemented in a microfluidic chip formed with a 3D printer by fused deposition modelling technology. As a material for chip fabrication, acrylonitrile butadiene styrene was chosen because of its mechanical and chemical stability. The chip contained the one chamber for the hydrolysis of the nucleic acid and another for the electrochemical detection by the modified GCE. This chamber was fabricated to allow for replacement of the GCE.

Efficient electricity production and simultaneously wastewater treatment via a high-performance photocatalytic fuel cell.

PubMed

Liu, Yanbiao; Li, Jinhua; Zhou, Baoxue; Li, Xuejin; Chen, Hongchong; Chen, Quanpeng; Wang, Zhongsheng; Li, Lei; Wang, Jiulin; Cai, Weimin

2011-07-01

A great quantity of wastewater were discharged into water body, causing serious environmental pollution. Meanwhile, the organic compounds in wastewater are important sources of energy. In this work, a high-performance short TiO(2) nanotube array (STNA) electrode was applied as photoanode material in a novel photocatalytic fuel cell (PFC) system for electricity production and simultaneously wastewater treatment. The results of current work demonstrate that various model compounds as well as real wastewater samples can be used as substrates for the PFC system. As a representative of model compounds, the acetic acid solution produces the highest cell performance with short-circuit current density 1.42 mA cm(-2), open-circuit voltage 1.48 V and maximum power density output 0.67 mW cm(-2). The STNA photoanode reveals obviously enhanced cell performance compared with TiO(2) nanoparticulate film electrode or other long nanotubes electrode. Moreover, the photoanode material, electrolyte concentration, pH of the initial solution, and cathode material were found to be important factors influencing the system performance of PFC. Therefore, the proposed fuel cell system provides a novel way of energy conversion and effective disposal mode of organics and serves well as a promising technology for wastewater treatment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Facile synthesis of birnessite-type manganese oxide nanoparticles as supercapacitor electrode materials.

PubMed

Liu, Lihu; Luo, Yao; Tan, Wenfeng; Zhang, Yashan; Liu, Fan; Qiu, Guohong

2016-11-15

Manganese oxides are environmentally benign supercapacitor electrode materials and, in particular, birnessite-type structure shows very promising electrochemical performance. In this work, nanostructured birnessite was facilely prepared by adding dropwise NH2OH·HCl to KMnO4 solution under ambient temperature and pressure. In order to fully exploit the potential of birnessite-type manganese oxide electrode materials, the effects of specific surface area, pore size, content of K(+), and manganese average oxidation state (Mn AOS) on their electrochemical performance were studied. The results showed that with the increase of NH2OH·HCl, the Mn AOS decreased and the corresponding pore sizes and specific surface area of birnessite increased. The synthesized nanostructured birnessite showed the highest specific capacitance of 245Fg(-1) at a current density of 0.1Ag(-1) within a potential range of 0-0.9V, and excellent cycle stability with a capacitance retention rate of 92% after 3000 cycles at a current density of 1.0Ag(-1). The present work implies that specific capacitance is mainly affected by specific surface area and pore volume, and provides a new method for the facile preparation of birnessite-type manganese oxide with excellent capacitive performance. Copyright © 2016 Elsevier Inc. All rights reserved.

Carbon/ λ-MnO 2 composites for supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Malak-Polaczyk, A.; Matei-Ghimbeu, C.; Vix-Guterl, C.; Frackowiak, E.

2010-04-01

In the present work a composite of carbon with λ-MnO 2 have been synthesized by a simple two-step route. In the first step, to obtain LiMn 2O 4/carbon material, mesoporous activated carbon was impregnated with the solution of precursor metal salts and heated subsequently. As-prepared materials were acid treated which resulted in the formation of λ-MnO 2/carbon. Physical properties, structure and specific surface area of electrode materials were studied by TEM, X-ray diffraction and nitrogen sorption measurements. Voltammetry cycling, galvanostatic charge/discharge and impedance spectroscopy measurements performed in two- and three-electrode cells have been applied in order to measure electrochemical parameters. TEM images confirmed well dispersed λ-MnO 2 particles on the surface of carbon material. The carbon in the composite plays an important role as the surface area enhancing component and a support of pseudocapacitive material. Furthermore, the through-connected porosity serves as a continuous pathway for electrolyte transport. A synergetic effect of the porous carbon framework and of the redox properties of the λ-MnO 2 is at the origin of improvement of specific capacitance values which has been observed for composites after delithiation.

Thorium-Free Versus Thoriated Plasma Gun Electrodes: Statistical Evaluation of Coating Properties

NASA Astrophysics Data System (ADS)

Colmenares-Angulo, Jose; Molz, Ronald; Hawley, David; Seshadri, Ramachandran Chidambaram

2016-04-01

Industries throughout the world today have an increased awareness of environmental, health, and safety issues. This, together with recent Nuclear Regulatory Commission changes concerning source material (e.g., thorium) has added complexity in the supply chain of thoriated tungsten commonly used in plasma spray gun spares. In the interest of a safer and more sustainable work environment, Oerlikon Metco has developed thorium-free material solutions proven to have longer service life than conventional thoriated spares. This work reports on the effect, if any, caused by tungsten compositional changes and extended service life in coating properties. Microstructure, coating efficiency parameters, hardness, particle state, in situ coating stress, and ex situ modulus are evaluated over the service life duration of the nozzle, comparing coatings with thoriated and non-thoriated nozzles and electrodes with the same spray parameters.

Mixed ionic-electronic conductors for electrodes of barium cerate-based SOFCS

NASA Astrophysics Data System (ADS)

Wu, Zhonglin

Gadolinium doped barium cerates (BCGs) have been identified as promising electrolyte materials for intermediate-temperature solid oxide fuel cells (SOFCs). It is crucial to develop compatible electrode materials for such electrolytes. Mixed ionic-electronic conductor (MIEC) electrode materials developed for SOFCs based on yttrium-stabilized zirconia (YSZ) may be used as electrode materials for BCG-based SOFCs; but a careful re-evaluation is required due to the intrinsic differences between BCG and YSZ. The performance of these electrode materials depends critically the transport of ionic and electronic species as well as gas. Accordingly, a profound understanding of transport in MIEC electrodes is imperative to effective design of high performance SOFCs. In this thesis, ambipolar transport in composite MIEC electrodes has been modeled using percolation theory to predict the effect of volume fractions of constituent phases and porosity on ambipolar conductivity. Transport and electrode kinetics of homogeneous MIEC electrodes have also been formulated under a steady-state condition to predict the distributions of ionic defects and current carried by each defect in such electrodes. Effects of catalytic properties, transport properties, and microstructure of porous electrodes and interfaces on the electrode performance are investigated. Under the guidelines of the theoretical modeling, several MIEC electrode materials are developed. Lasb{1-x}Srsb{x}Cosb{1-x}Fesb{y}Osb{3-delta} homogeneous materials are studied as cathode materials. However, the interfacial resistance seems too high due to the lack of catalytic activity at intermediate temperatures. Results indicate that Ag-Bisb{1.5}Ysb{0.5}Osb3 composite MIECs are good cathode materials when the volume fractions of constituent phases and porosity are carefully controlled. Such electrodes have low interfacial resistance, better binding strength, and smaller thermal mismatch with the BCG electrolyte, compared to other metal electrodes (such as Pt and Ag). Ni-BCG composite MIECs are studied as anode materials. It is found that electrodes prepared from NiO and reduced to Ni in situ is not catalytically active because of diffusion of NiO into BCG, which forms a resistive layer. Electrodes prepared from Ni metal and fired in an inert or reducing atmosphere exhibit low interfacial resistance and good compatibility with BCG electrolyte. Stability of these developed electrode materials is investigated under conditions pertinent to SOFCs.

Enhanced tolerance to stretch-induced performance degradation of stretchable MnO2-based supercapacitors.

PubMed

Huang, Yan; Huang, Yang; Meng, Wenjun; Zhu, Minshen; Xue, Hongtao; Lee, Chun-Sing; Zhi, Chunyi

2015-02-04

The performance of many stretchable electronics, such as energy storage devices and strain sensors, is highly limited by the structural breakdown arising from the stretch imposed. In this article, we focus on a detailed study on materials matching between functional materials and their conductive substrate, as well as enhancement of the tolerance to stretch-induced performance degradation of stretchable supercapacitors, which are essential for the design of a stretchable device. It is revealed that, being widely utilized as the electrode material of the stretchable supercapacitor, metal oxides such as MnO2 nanosheets have serious strain-induced performance degradation due to their rigid structure. In comparison, with conducting polymers like a polypyrrole (PPy) film as the electrochemically active material, the performance of stretchable supercapacitors can be well preserved under strain. Therefore, a smart design is to combine PPy with MnO2 nanosheets to achieve enhanced tolerance to strain-induced performance degradation of MnO2-based supercapacitors, which is realized by fabricating an electrode of PPy-penetrated MnO2 nanosheets. The composite electrodes exhibit a remarkable enhanced tolerance to strain-induced performance degradation with well-preserved performance over 93% under strain. The detailed morphology and electrochemical impedance variations are investigated for the mechanism analyses. Our work presents a systematic investigation on the selection and matching of electrode materials for stretchable supercapacitors to achieve high performance and great tolerance to strain, which may guide the selection of functional materials and their substrate materials for the next-generation of stretchable electronics.

Dye sensitized solar cell (DSSC) with natural dyes extracted from Jatropha leaves and purple Chrysanthemum flowers as sensitizer

NASA Astrophysics Data System (ADS)

Tahir, Dahlang; Satriani, Wilda; Gareso, P. L.; Abdullah, B.

2018-03-01

DSSC (Dye-Sensitized Solar Cell) prototype has been investigated using Jatropha leaves and purple Chrysanthemum flowers as natural dyes. DSSC consists of working electrode and counter electrode. A working electrode composed of semiconductor nanoparticles TiO2 that has been coated with dye molecules. Dye molecules serve as light photon catchers, while semiconductor nanoparticles TiO2 function to absorb and forward photons into electrons. In the electrode counter given catalyst carbon, serves to accelerate the reaction kinetics of triiodide reduction process on transparent conductive oxide (TCO). DSSC using TiO2 as a semiconductor material and natural dyes as sensitizer from Jatropha leaves and purple Chrysanthemum flowers are successful produced. The physical properties of the working electrode have been determined by using XRD and the chemical properties of the TiO2 powder and dye powder using FTIR and dye solution using UV-Vis. The resulted fabrications are also examined its I-V characteristics. The best performance is generated by mixed dye 1.91 x 10-3 % compared than those DSSC for dye extracted from Jatropha leaves or purple Chrysanthemum. The characterization results show that the higher of the absorption wavelength of the DSSC efficiency is high.

Hurdles to organic quinone flow cells. Electrode passivation by quinone reduction in acetonitrile Li electrolytes

NASA Astrophysics Data System (ADS)

Rueda-García, D.; Dubal, D. P.; Huguenin, F.; Gómez-Romero, P.

2017-05-01

The uses of quinones in Redox Flow Batteries (RFBs) has been mainly circumscribed to aqueous solutions (of derivatives with polar groups) despite a larger solubility and wider electrochemical window provided by organic media. The redox mechanism of quinones in protic media is simpler and better known than in aprotic media, where radical species are involved. This paper reports the behaviour of methyl-p-benzoquinone (MBQ) under electrochemical reduction conditions in a LiClO4sbnd CH3CN electrolyte and various working electrodes. We detected the reversible generation of a bright green coating on the working electrode and the subsequent formation of a polymer (the nature of which depends on the presence or absence of oxygen). These coatings prevent the regular redox process of methyl-p-benzoquinone from taking place on the surface of the electrode and is generated regardless of the electrode material used or the presence of O2 in solution. In addition to MBQ, the green passivating layer was also found for less sterically hindered quinones such as p-benzoquinone or 1,4-naphthoquinone, but not for anthraquinone. We have also shown the central role of Li+ in the formation of this green layer. This work provides important guidelines for the final use of quinones in RFBs with organic electrolytes.

Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance

NASA Astrophysics Data System (ADS)

Asfaw, Habtom D.; Roberts, Matthew R.; Tai, Cheuk-Wai; Younesi, Reza; Valvo, Mario; Nyholm, Leif; Edström, Kristina

2014-07-01

In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm-2 at 0.1 mA cm-2 (lowest rate) and 1.1 mA h cm-2 at 6 mA cm-2 (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm-2 at 0.1 mA cm-2 (lowest rate) and 1.1 mA h cm-2 at 6 mA cm-2 (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01682c

Battery structures, self-organizing structures, and related methods

DOEpatents

Chiang, Yet-Ming; Moorehead, William Douglas

2013-11-19

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling forve on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionicaily conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery Structures, self-organizing structures, and related methods

DOEpatents

Chiang, Yet-Ming; Moorehead, William Douglas

2013-11-12

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet-Ming [Framingham, MA; Moorehead, William Douglas [Virginia Beach, VA

2012-06-26

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet Ming [Framingham, MA; Moorehead, William Douglas [Virginia Beach, VA; Gozdz, Antoni S [Marlborough, MA; Holman, Richard K [Belmont, MA; Loxley, Andrew [Somerville, MA; Riley, Jr., Gilbert N.; Viola, Michael S [Burlington, MA

2009-08-25

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet-Ming [Framingham, MA; Moorehead, William D [Virginia Beach, VA; Gozdz, Antoni S [Marlborough, MA; Holman, Richard K [Belmont, MA; Loxley, Andrew L [Roslindale, MA; Riley, Jr., Gilbert N.; Viola, Michael S [Burlington, MA

2012-05-01

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet-Ming [Framingham, MA; Moorehead, William D [Virginia Beach, VA; Gozdz, Antoni S [Marlborough, MA; Holman, Richard K [Belmont, MA; Loxley, Andrew L [Roslindale, MA; Riley, Jr., Gilbert N.; Viola, Michael S [Burlington, MA

2011-08-02

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Complaint liquid metal electrodes for dielectric elastomer actuators

NASA Astrophysics Data System (ADS)

Finkenauer, Lauren R.; Majidi, Carmel

2014-03-01

This work presents a liquid-phase metal electrode to be used with poly(dimethylsiloxane) (PDMS) for a dielectric elastomer actuator (DEA). DEAs are favorable for soft-matter applications where high efficiency and response times are desirable. A consistent challenge faced during the fabrication of these devices is the selection and deposition of electrode material. While numerous designs have been demonstrated with a variety of conductive elastomers and greases, these materials have significant and often intrinsic shortcomings, e.g. low conductivity, hysteresis, incapability of large deformations, and complex fabrication requirements. The liquid metal alloy eutectic Gallium-Indium (EGaIn) is a promising alternative to existing compliant electrodes, having both high conductivity and complete soft-matter functionality. The liquid electrode shares almost the same electrical conductivity as conventional metal wiring and provides no mechanical resistance to bending or stretching of the DEA. This research establishes a straightforward and effective method for quickly depositing EGaIn electrodes, which can be adapted for batch fabrication, and demonstrates the successful actuation of sample curved cantilever elastomer actuators using these electrodes. As with the vast majority of electrostatically actuated elastomer devices, the voltage requirements for these curved DEAs are still quite significant, though modifications to the fabrication process show some improved electrical properties. The ease and speed with which this method can be implemented suggests that the development of a more electronically efficient device is realistic and worthwhile.

Experimental and Theoretical Studies of Nanostructured Electrodes for Use in Dye-Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Gong, Jiawei

Among various photovoltaic technologies available in the emerging market, dye-sensitized solar cells (DSSCs) are deemed as an effective, competitive solution to the increasing demand for high-efficiency PV devices. To move towards full commercialization, challenges remain in further improvement of device stability as well as reduction of material and manufacturing costs. This study aims at rational synthesis and photovoltaic characterization of two nanostructured electrode materials (i.e. SnO2 nanofibers and activated graphene nanoplatelets) for use as photoanode and counter electrode in dye-sensitized solar cells. The main objective is to explore the favorable charge transport features of SnO2 nanofiber network and simultaneously replace the high-priced conventional electrocatalytic nanomaterials (e.g. Pt nanoparticles) used in existing counter electrode of DSSCs. To achieve this objective, a multiphysics model of electrode kinetics was developed to optimize various design parameters and cell configurations. The porous hollow SnO2 nanofibers were successfully synthesized via a facile route consisting of electrospinning precursor polymer nanofibers, followed by controlled carbonization. The novel SnO2/TiO2 composite photoanode materials carry advantages of SnO2 nanofiber network (e.g. nanostructural continuity, high electron mobility) and TiO2 nanoparticles (e.g. high specific area), and therefore show excellent photovoltaic properties including improved short-circuit current and fill factors. In addition, hydrothermally activated graphene nanoplatelets (aGNP) were used as a catalytic counter electrode material to substitute for conventionally used platinum nanoparticles. Improved catalytic performance of aGNP electrode was achieved through increased surface area and better control of morphology. Dye-sensitized solar cells using these aGNP electrodes had power conversion efficiencies comparable to those using platinum nanoparticles with I-/I3- redox mediators. Moreover, a multiphysics model at the device level was developed to predict the power output characteristics of DSSC using different electrode materials. The developed model was validated by the experimental data acquired from lab-fabricated DSSCs. Further, parametric simulation was conducted to analyze the effect of series resistance, shunt resistance, interfacial overpotential, as well as difference between the conduction band and formal redox potentials on device performance. This model correlates the maximum power output of DSSC devices to various design and operating parameters, and it also provides insight into the working principles of newly designed devices.

Electrophoretic deposition of thermites onto micro-engineered electrodes prepared by direct-ink writing.

PubMed

Sullivan, K T; Zhu, C; Tanaka, D J; Kuntz, J D; Duoss, E B; Gash, A E

2013-02-14

This work combines electrophoretic deposition (EPD) with direct-ink writing (DIW) to prepare thin films of Al/CuO thermites onto patterned two- and three-dimensional silver electrodes. DIW was used to write the electrodes using a silver nanoparticle ink, and EPD was performed in a subsequent step to deposit the thermite onto the conductive electrodes. Unlike conventional lithographic techniques, DIW is a low-cost and versatile alternative to print fine-featured electrodes, and adds the benefit of printing self-supported three-dimensional structures. EPD provides a method for depositing the composite thermite only onto the conductive electrodes, and with controlled thicknesses, which provides fine spatial and mass control, respectively. EPD has previously been shown to produce well-mixed thermite composites which can pack to reasonably high densities without the need for any postprocessing. Homogeneous mixing is particularly important in reactive composities, where good mixing can enhance the reaction kinetics by decreasing the transport distance between the components. Several two- and three-dimensional designs were investigated to highlight the versatility of using DIW and EPD together. In addition to energetic applications, we anticipate that this combination of techniques will have a variety of other applications, which would benefit from the controlled placement of a thin film of one material onto a conductive architecture of a second material.

A Novel Ni/WOX/W Resistive Random Access Memory with Excellent Retention and Low Switching Current

NASA Astrophysics Data System (ADS)

Chien, Wei-Chih; Chen, Yi-Chou; Lee, Feng-Ming; Lin, Yu-Yu; Lai, Erh-Kun; Yao, Yeong-Der; Gong, Jeng; Horng, Sheng-Fu; Yeh, Chiao-Wen; Tsai, Shih-Chang; Lee, Ching-Hsiung; Huang, Yu-Kai; Chen, Chun-Fu; Kao, Hsiao-Feng; Shih, Yen-Hao; Hsieh, Kuang-Yeu; Lu, Chih-Yuan

2011-04-01

The behavior of WOX resistive random access memory (ReRAM) is a strong function of the top electrode material, which controls the conduction mechanism and the forming process. When using a top electrode with low work function, the current conduction is limited by space charges. On the other hand, the mechanism becomes thermionic emission for devices with a high work function top electrode. These (thermionic) devices are also found to have higher initial resistance, reduced forming current, and larger resistance window. Based on these insights and considering the compatibility to complementary metal-oxide-semiconductor (CMOS) process, we proposed to use Ni as the top electrode for high performance WOX ReRAM devices. The new Ni/WOX/W device can be switched at a low current density less than 8×105 A/cm2, with RESET/SET resistance ratio greater than 100, and extremely good data retention of more than 300 years at 85 °C.

Silicone-Based Triboelectric Nanogenerator for Water Wave Energy Harvesting.

PubMed

Xiao, Tian Xiao; Jiang, Tao; Zhu, Jian Xiong; Liang, Xi; Xu, Liang; Shao, Jia Jia; Zhang, Chun Lei; Wang, Jie; Wang, Zhong Lin

2018-01-31

Triboelectric nanogenerator (TENG) has been proven to be efficient for harvesting water wave energy, which is one of the most promising renewable energy sources. In this work, a TENG with a silicone rubber/carbon black composite electrode was designed for converting the water wave energy into electricity. The silicone-based electrode with a soft texture provides a better contact with the dielectric film. Furthermore, a spring structure is introduced to transform low-frequency water wave motions into high-frequency vibrations. They together improve the output performance and efficiency of TENG. The output performances of TENGs are further enhanced by optimizing the triboelectric material pair and tribo-surface area. A spring-assisted TENG device with the segmented silicone rubber-based electrode structure was sealed into a waterproof box, which delivers a maximum power density of 2.40 W m -3 , as triggered by the water waves. The present work provides a new strategy for fabricating high-performance TENG devices by coupling flexible electrodes and spring structure for harvesting water wave energy.

Recent research progress on iron- and manganese-based positive electrode materials for rechargeable sodium batteries

PubMed Central

Yabuuchi, Naoaki; Komaba, Shinichi

2014-01-01

Large-scale high-energy batteries with electrode materials made from the Earth-abundant elements are needed to achieve sustainable energy development. On the basis of material abundance, rechargeable sodium batteries with iron- and manganese-based positive electrode materials are the ideal candidates for large-scale batteries. In this review, iron- and manganese-based electrode materials, oxides, phosphates, fluorides, etc, as positive electrodes for rechargeable sodium batteries are reviewed. Iron and manganese compounds with sodium ions provide high structural flexibility. Two layered polymorphs, O3- and P2-type layered structures, show different electrode performance in Na cells related to the different phase transition and sodium migration processes on sodium extraction/insertion. Similar to layered oxides, iron/manganese phosphates and pyrophosphates also provide the different framework structures, which are used as sodium insertion host materials. Electrode performance and reaction mechanisms of the iron- and manganese-based electrode materials in Na cells are described and the similarities and differences with lithium counterparts are also discussed. Together with these results, the possibility of the high-energy battery system with electrode materials made from only Earth-abundant elements is reviewed. PMID:27877694

Recent research progress on iron- and manganese-based positive electrode materials for rechargeable sodium batteries.

PubMed

Yabuuchi, Naoaki; Komaba, Shinichi

2014-08-01

Large-scale high-energy batteries with electrode materials made from the Earth-abundant elements are needed to achieve sustainable energy development. On the basis of material abundance, rechargeable sodium batteries with iron- and manganese-based positive electrode materials are the ideal candidates for large-scale batteries. In this review, iron- and manganese-based electrode materials, oxides, phosphates, fluorides, etc, as positive electrodes for rechargeable sodium batteries are reviewed. Iron and manganese compounds with sodium ions provide high structural flexibility. Two layered polymorphs, O3- and P2-type layered structures, show different electrode performance in Na cells related to the different phase transition and sodium migration processes on sodium extraction/insertion. Similar to layered oxides, iron/manganese phosphates and pyrophosphates also provide the different framework structures, which are used as sodium insertion host materials. Electrode performance and reaction mechanisms of the iron- and manganese-based electrode materials in Na cells are described and the similarities and differences with lithium counterparts are also discussed. Together with these results, the possibility of the high-energy battery system with electrode materials made from only Earth-abundant elements is reviewed.

Organic thin film transistor with a simplified planar structure

NASA Astrophysics Data System (ADS)

Zhang, Lei; Yu, Jungsheng; Zhong, Jian; Jiang, Yadong

2009-05-01

Organic thin film transistor (OTFT) with a simplified planar structure is described. The gate electrode and the source/drain electrodes of OTFT are processed in one planar structure. And these three electrodes are deposited on the glass substrate by DC sputtering technology using Cr/Ni target. Then the electrode layouts of different width length ratio are made by photolithography technology at the same time. Only one step of deposition and one step of photolithography is needed while conventional process takes at least two steps of deposition and two steps of photolithography. Metal is first prepared on the other side of glass substrate and electrode is formed by photolithography. Then source/drain electrode is prepared by deposition and photolithography on the side with the insulation layer. Compared to conventional process of OTFTs, the process in this work is simplified. After three electrodes prepared, the insulation layer is made by spin coating method. The organic material of polyimide is used as the insulation layer. A small molecular material of pentacene is evaporated on the insulation layer using vacuum deposition as the active layer. The process of OTFTs needs only three steps totally. A semi-auto probe stage is used to connect the three electrodes and the probe of the test instrument. A charge carrier mobility of 0.3 cm2 /V s, is obtained from OTFTs on glass substrates with and on/off current ratio of 105. The OTFTs with the planar structure using simplified process can simplify the device process and reduce the fabrication cost.

Electrochemical Determination of Chlorpyrifos on a Nano-TiO₂Cellulose Acetate Composite Modified Glassy Carbon Electrode.

PubMed

Kumaravel, Ammasai; Chandrasekaran, Maruthai

2015-07-15

A rapid and simple method of determination of chlorpyrifos is important in environmental monitoring and quality control. Electrochemical methods for the determination of pesticides are fast, sensitive, reproducible, and cost-effective. The key factor in electrochemical methods is the choice of suitable electrode materials. The electrode materials should have good stability, reproducibility, more sensitivity, and easy method of preparation. Mercury-based electrodes have been widely used for the determination of chlorpyrifos. From an environmental point of view mercury cannot be used. In this study a biocompatible nano-TiO2/cellulose acetate modified glassy carbon electrode was prepared by a simple method and used for the electrochemical sensing of chlorpyrifos in aqueous methanolic solution. Electroanalytical techniques such as cyclic voltammetry, differential pulse voltammetry, and amperometry were used in this work. This electrode showed very good stability, reproducibility, and sensitivity. A well-defined peak was obtained for the reduction of chlorpyrifos in cyclic voltammetry and differential pulse voltammetry. A smooth noise-free current response was obtained in amperometric analysis. The peak current obtained was proportional to the concentration of chlorpyrifos and was used to determine the unknown concentration of chlorpyrifos in the samples. Analytical parameters such as LOD, LOQ, and linear range were estimated. Analysis of real samples was also carried out. The results were validated through HPLC. This composite electrode can be used as an alternative to mercury electrodes reported in the literature.

Hierarchical Fe₃O₄@Fe₂O₃ Core-Shell Nanorod Arrays as High-Performance Anodes for Asymmetric Supercapacitors.

PubMed

Tang, Xiao; Jia, Ruyue; Zhai, Teng; Xia, Hui

2015-12-16

Anode materials with relatively low capacitance remain a great challenge for asymmetric supercapacitors (ASCs) to pursue high energy density. Hematite (α-Fe2O3) has attracted intensive attention as anode material for ASCs, because of its suitable reversible redox reactions in a negative potential window (from 0 V to -1 V vs Ag/AgCl), high theoretical capacitance, rich abundance, and nontoxic features. Nevertheless, the Fe2O3 electrode cannot deliver large volumetric capacitance at a high rate, because of its poor electrical conductivity (∼10(-14) S/cm), resulting in low power density and low energy density. In this work, a hierarchical heterostructure comprising Fe3O4@Fe2O3 core-shell nanorod arrays (NRAs) is presented and investigated as the negative electrode for ASCs. Consequently, the Fe3O4@Fe2O3 electrode exhibits superior supercapacitive performance, compared to the bare Fe2O3 and Fe3O4 NRAs electrodes, demonstrating large volumetric capacitance (up to 1206 F/cm(3) with a mass loading of 1.25 mg/cm(2)), as well as good rate capability and cycling stability. The hybrid electrode design is also adopted to prepare Fe3O4@MnO2 core-shell NRAs as the positive electrode for ASCs. Significantly, the as-assembled 2 V ASC device delivered a high energy density of 0.83 mWh/cm(3) at a power density of 15.6 mW/cm(3). This work constitutes the first demonstration of Fe3O4 as the conductive supports for Fe2O3 to address the concerns about its poor electronic and ionic transport.

Graphene oxide/graphene vertical heterostructure electrodes for highly efficient and flexible organic light emitting diodes

NASA Astrophysics Data System (ADS)

Jia, S.; Sun, H. D.; Du, J. H.; Zhang, Z. K.; Zhang, D. D.; Ma, L. P.; Chen, J. S.; Ma, D. G.; Cheng, H. M.; Ren, W. C.

2016-05-01

The relatively high sheet resistance, low work function and poor compatibility with hole injection layers (HILs) seriously limit the applications of graphene as transparent conductive electrodes (TCEs) for organic light emitting diodes (OLEDs). Here, a graphene oxide/graphene (GO/G) vertical heterostructure is developed as TCEs for high-performance OLEDs, by directly oxidizing the top layer of three-layer graphene films with ozone treatment. Such GO/G heterostructure electrodes show greatly improved optical transmittance, a large work function, high stability, and good compatibility with HIL materials (MoO3 in this work). Moreover, the conductivity of the heterostructure is not sacrificed compared to the pristine three-layer graphene electrodes, but is significantly higher than that of pristine two-layer graphene films. In addition to high flexibility, OLEDs with different emission colors based on the GO/G heterostructure TCEs show much better performance than those based on indium tin oxide (ITO) anodes. Green OLEDs with GO/G heterostructure electrodes have the maximum current efficiency and power efficiency, as high as 82.0 cd A-1 and 98.2 lm W-1, respectively, which are 36.7% (14.8%) and 59.2% (15.0%) higher than those with pristine graphene (ITO) anodes. These findings open up the possibility of using graphene for next generation high-performance flexible and wearable optoelectronics with high stability.The relatively high sheet resistance, low work function and poor compatibility with hole injection layers (HILs) seriously limit the applications of graphene as transparent conductive electrodes (TCEs) for organic light emitting diodes (OLEDs). Here, a graphene oxide/graphene (GO/G) vertical heterostructure is developed as TCEs for high-performance OLEDs, by directly oxidizing the top layer of three-layer graphene films with ozone treatment. Such GO/G heterostructure electrodes show greatly improved optical transmittance, a large work function, high stability, and good compatibility with HIL materials (MoO3 in this work). Moreover, the conductivity of the heterostructure is not sacrificed compared to the pristine three-layer graphene electrodes, but is significantly higher than that of pristine two-layer graphene films. In addition to high flexibility, OLEDs with different emission colors based on the GO/G heterostructure TCEs show much better performance than those based on indium tin oxide (ITO) anodes. Green OLEDs with GO/G heterostructure electrodes have the maximum current efficiency and power efficiency, as high as 82.0 cd A-1 and 98.2 lm W-1, respectively, which are 36.7% (14.8%) and 59.2% (15.0%) higher than those with pristine graphene (ITO) anodes. These findings open up the possibility of using graphene for next generation high-performance flexible and wearable optoelectronics with high stability. Electronic supplementary information (ESI) available: XPS spectra, Raman spectra, sheet resistance and transmittance of graphene films with different numbers of layers and different ozone treatment times, doping effect of MoO3 on graphene and GO/G electrodes, performance of green OLEDs with different graphene anodes, a movie showing the flexibility of device. See DOI: 10.1039/c6nr01649a

Segmentally structured disk triboelectric nanogenerator

DOEpatents

Wang, Zhong Lin; Zhu, Guang; Lin, Long; Wang, Sihong; Chen, Jun

2016-11-01

A generator includes a disc shaped first unit, a disc shaped second unit and an axle. The first unit includes a substrate layer, a double complementary electrode layer and an electrification material layer. The electrode layer includes a first electrode member and a second electrode member. The first electrode member includes evenly spaced apart first electrode legs extending inwardly. The second electrode member is complementary in shape to the first electrode member. The legs of the first electrode member and the second electrode member are interleaved with each other and define a continuous gap therebetween. The electrification material includes a first material that is in a first position on the triboelectric series. The second unit defines elongated openings and corresponding elongated leg portions, and includes a second material that is at a second position on a triboelectric series, different than the first position.

Novel air electrode for metal-air battery with new carbon material and method of making same

DOEpatents

Ross, Jr., Philip N.

1990-01-01

A novel carbonaceous electrode support material is disclosed characterized by a corrosion rate of 0.03 wt. %/hour or less when measured a5 550 millivolts vs. a Hg/HgO electrode in a 30 wt. % KOH electrolyte a5 30.degree. C. The electrode support material comprises a preselected carbon black material which has been heat-treated by heating the material to a temperature of from about 2500.degree. to about 3000.degree. C. over a period of from about 1 to about 5 hours in an inert atmosphere and then maintaining the preselected carbon black material at this temperature for a period of at least about 1 hour, and preferably about 2 hours, in the inert atmosphere. A carbonaceous electrode suitable for use as an air electrode in a metal-air cell may be made from the electrode support material by shaping and forming it into a catalyst support and then impregnating it with a catalytically active material capable of catalyzing the reaction with oxygen at the air electrode of metal-air cell.

Nuclear Fusion Blast and Electrode Lifetimes in a PJMIF Reactor

NASA Astrophysics Data System (ADS)

Thio, Y. C. Francis; Witherspoon, F. D.; Case, A.; Brockington, S.; Cruz, E.; Luna, M.; Hsu, S. C.

2017-10-01

We present an analysis and numerical simulation of the nuclear blast from the micro-explosion following the completion of the fusion burn for a baseline design of a PJMIF fusion reactor with a fusion gain of 20. The stagnation pressure from the blast against the chamber wall defines the engineering requirement for the structural design of the first wall and the plasma guns. We also present an analysis of the lifetimes of the electrodes of the plasma guns which are exposed to (1) the high current, and (2) the neutron produced by the fusion reactions. We anticipate that the gun electrodes are made of tungsten alloys as plasma facing components reinforced structurally by appropriate steel alloys. Making reasonable assumptions about the electrode erosion rate (100 ng/C transfer), the electrode lifetime limited by the erosion rate is estimated to be between 19 and 24 million pulses before replacement. Based on known neutron radiation effects on structural materials such as steel alloys and plasma facing component materials such as tungsten alloys, the plasma guns are expected to survive some 22 million shots. At 1 Hz, this equal to about 6 months of continuous operation before they need to be replaced. Work supported by Strong Atomics, LLC.

A Novel In-situ Electrochemical Cell for Neutron Diffraction Studies of Phase Transitions in Small Volume Electrodes of Li-ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vadlamani, Bhaskar S; An, Ke; Jagannathan, M.

2014-01-01

The design and performance of a novel in-situ electrochemical cell that greatly facilitates the neutron diffraction study of complex phase transitions in small volume electrodes of Li-ion cells, is presented in this work. Diffraction patterns that are Rietveld-refinable could be obtained simultaneously for all the electrodes, which demonstrates that the cell is best suited to explore electrode phase transitions driven by the lithiation and delithiation processes. This has been facilitated by the use of single crystal (100) Si sheets as casing material and the planar cell configuration, giving improved signal-to-noise ratio relative to other casing materials. The in-situ cell hasmore » also been designed for easy assembly and to facilitate rapid experiments. The effectiveness of cell is demonstrated by tracking the neutron diffraction patterns during the charging of graphite/LiCoO2 and graphite/LiMn2O4 cells. It is shown that good quality neutron diffraction data can be obtained and that most of the finer details of the phase transitions, and the associated changes in crystallographic parameters in these electrodes, can be captured.« less

Improved performance of organic solar cells with solution processed hole transport layer

NASA Astrophysics Data System (ADS)

Bhargav, Ranoo; Gairola, S. P.; Patra, Asit; Naqvi, Samya; Dhawan, S. K.

2018-06-01

This work is based on Cobalt Oxide as solution processed, inexpensive and effective hole transport layer (HTL) for efficient organic photovoltaic applications (OPVs). In Organic solar cell (OSC) devices ITO coated glass substrate used as a transparent anode electrode for light incident, HTL material Co3O4 dissolve in DMF solvent deposited on anode electrode, after that active layer material (donor/acceptor) deposited on to HTL and finally Al were deposited by thermal evaporation used as cathode electrode. These devices were fabricated with PCDTBT well known low band gap donor material in OSCs and blended with PC71BM as an acceptor material using simplest device structure ITO/Co3O4/active layer/Al at ambient conditions. The power conversion efficiencies (PCEs) based on Co3O4 and PEDOT:PSS have been achieved to up to 3.21% and 1.47% with PCDTBT respectively. In this study we reported that the devices fabricated with Co3O4 showed better performance as compare to the devices fabricated with well known and most studied solution processed HTL material PEDOT:PSS under identical environmental conditions. The surface morphology of the HTL film was characterized by (AFM). Lastly, we have provided Co3O4 as an efficient hole transport material HTL for solution processed organic photovoltaic applications.

X-ray Absorption Spectroscopy Characterization of Electrochemical Processes in Renewable Energy Storage and Conversion Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmand, Maryam

2013-05-19

The development of better energy conversion and storage devices, such as fuel cells and batteries, is crucial for reduction of our global carbon footprint and improving the quality of the air we breathe. However, both of these technologies face important challenges. The development of lower cost and better electrode materials, which are more durable and allow more control over the electrochemical reactions occurring at the electrode/electrolyte interface, is perhaps most important for meeting these challenges. Hence, full characterization of the electrochemical processes that occur at the electrodes is vital for intelligent design of more energy efficient electrodes. X-ray absorption spectroscopymore » (XAS) is a short-range order, element specific technique that can be utilized to probe the processes occurring at operating electrode surfaces, as well for studying the amorphous materials and nano-particles making up the electrodes. It has been increasingly used in recent years to study fuel cell catalysts through application of the and #916; and mgr; XANES technique, in combination with the more traditional X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) techniques. The and #916; and mgr; XANES data analysis technique, previously developed and applied to heterogeneous catalysts and fuel cell electrocatalysts by the GWU group, was extended in this work to provide for the first time space resolved adsorbate coverages on both electrodes of a direct methanol fuel cell. Even more importantly, the and #916; and mgr; technique was applied for the first time to battery relevant materials, where bulk properties such as the oxidation state and local geometry of a cathode are followed.« less

In situ electrochemical high-energy X-ray diffraction using a capillary working electrode cell geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, Matthias J.; Bedford, Nicholas M.; Jiang, Naisheng

The ability to generate new electrochemically active materials for energy generation and storage with improved properties will likely be derived from an understanding of atomic-scale structure/function relationships during electrochemical events. Here, the design and implementation of a new capillary electrochemical cell designed specifically forin situhigh-energy X-ray diffraction measurements is described. By increasing the amount of electrochemically active material in the X-ray path while implementing low-Zcell materials with anisotropic scattering profiles, an order of magnitude enhancement in diffracted X-ray signal over traditional cell geometries for multiple electrochemically active materials is demonstrated. This signal improvement is crucial for high-energy X-ray diffraction measurementsmore » and subsequent Fourier transformation into atomic pair distribution functions for atomic-scale structural analysis. As an example, clear structural changes in LiCoO 2under reductive and oxidative conditions using the capillary cell are demonstrated, which agree with prior studies. Accurate modeling of the LiCoO 2diffraction data using reverse Monte Carlo simulations further verifies accurate background subtraction and strong signal from the electrochemically active material, enabled by the capillary working electrode geometry.« less

Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

PubMed

Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

2014-01-01

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al2O3 ceramic.

Transition metal oxide as anode interface buffer for impedance spectroscopy

NASA Astrophysics Data System (ADS)

Xu, Hui; Tang, Chao; Wang, Xu-Liang; Zhai, Wen-Juan; Liu, Rui-Lan; Rong, Zhou; Pang, Zong-Qiang; Jiang, Bing; Fan, Qu-Li; Huang, Wei

2015-12-01

Impedance spectroscopy is a strong method in electric measurement, which also shows powerful function in research of carrier dynamics in organic semiconductors when suitable mathematical physical models are used. Apart from this, another requirement is that the contact interface between the electrode and materials should at least be quasi-ohmic contact. So in this report, three different transitional metal oxides, V2O5, MoO3 and WO3 were used as hole injection buffer for interface of ITO/NPB. Through the impedance spectroscopy and PSO algorithm, the carrier mobilities and I-V characteristics of the NPB in different devices were measured. Then the data curves were compared with the single layer device without the interface layer in order to investigate the influence of transitional metal oxides on the carrier mobility. The careful research showed that when the work function (WF) of the buffer material was just between the work function of anode and the HOMO of the organic material, such interface material could work as a good bridge for carrier injection. Under such condition, the carrier mobility measured through impedance spectroscopy should be close to the intrinsic value. Considering that the HOMO (or LUMO) of most organic semiconductors did not match with the work function of the electrode, this report also provides a method for wide application of impedance spectroscopy to the research of carrier dynamics.

Electrochemical and mechanical polishing and shaping method and system

NASA Technical Reports Server (NTRS)

Engelhaupt, Darell E. (Inventor); Gubarev, Mikhail V. (Inventor); Jones, William David (Inventor); Ramsey, Brian D. (Inventor); Benson, Carl M. (Inventor)

2011-01-01

A method and system are provided for the shaping and polishing of the surface of a material selected from the group consisting of electrically semi-conductive materials and conductive materials. An electrically non-conductive polishing lap incorporates a conductive electrode such that, when the polishing lap is placed on the material's surface, the electrode is placed in spaced-apart juxtaposition with respect to the material's surface. A liquid electrolyte is disposed between the material's surface and the electrode. The electrolyte has an electrochemical stability constant such that cathodic material deposition on the electrode is not supported when a current flows through the electrode, the electrolyte and the material. As the polishing lap and the material surface experience relative movement, current flows through the electrode based on (i) adherence to Faraday's Law, and (ii) a pre-processing profile of the surface and a desired post-processing profile of the surface.

Organic photosensitive cells grown on rough electrode with nano-scale morphology control

DOEpatents

Yang, Fan [Piscataway, NJ; Forrest, Stephen R [Ann Arbor, MI

2011-06-07

An optoelectronic device and a method for fabricating the optoelectronic device includes a first electrode disposed on a substrate, an exposed surface of the first electrode having a root mean square roughness of at least 30 nm and a height variation of at least 200 nm, the first electrode being transparent. A conformal layer of a first organic semiconductor material is deposited onto the first electrode by organic vapor phase deposition, the first organic semiconductor material being a small molecule material. A layer of a second organic semiconductor material is deposited over the conformal layer. At least some of the layer of the second organic semiconductor material directly contacts the conformal layer. A second electrode is deposited over the layer of the second organic semiconductor material. The first organic semiconductor material is of a donor-type or an acceptor-type relative to the second organic semiconductor material, which is of the other material type.

Layer-by-layer self-assembled two-dimensional MXene/layered double hydroxide composites as cathode for alkaline hybrid batteries

NASA Astrophysics Data System (ADS)

Dong, Xiaowan; Zhang, Yadi; Ding, Bing; Hao, Xiaodong; Dou, Hui; Zhang, Xiaogang

2018-06-01

Multifarious layered materials have received extensive concern in the field of energy storage due to their distinctive two-dimensional (2D) structure. However, the natural tendency to be re-superimposed and the inherent disadvantages of a single 2D material significantly limit their performance. In this work, the delaminated Ti3C2Tx (d-Ti3C2Tx)/cobalt-aluminum layered double hydroxide (Ti3C2Tx/CoAl-LDH) composites are prepared by layer-by-layer self-assembly driven by electrostatic interaction. The alternate Ti3C2Tx and CoAl-LDH layers prevent each other from restacking and the obtained Ti3C2Tx/CoAl-LDH heterostructure combine the advantages of high electron conductivity of Ti3C2Tx and high electrochemical activity of CoAl-LDH, thus effectively improving the electrochemical reactivity of electrode materials and accelerating the kinetics of Faraday reaction. As a consequence, as a cathode for alkaline hybrid battery, the Ti3C2Tx/CoAl-LDH electrode exhibits a high specific capacity of 106 mAh g-1 at a current density of 0.5 A g-1 and excellent rate capability (78% at 10 A g-1), with an excellent cycling stability of 90% retention after 5000 cycles at 4 A g-1. This work provides an alternative route to design advanced 2D electrode materials, thus exploiting their full potentials for alkaline hybrid batteries.

Application of Light-cured Dental Adhesive Resin for Mounting Electrodes or Microdialysis Probes in Chronic Experiments

PubMed Central

Okumura, Tetsu; Okanoya, Kazuo; Tani, Jun

2007-01-01

In chronic recording experiments, self-curing dental acrylic resins have been used as a mounting base of electrodes or microdialysis-probes. Since these acrylics do not bond to the bone, screws have been used as anchors. However, in small experimental animals like finches or mouse, their craniums are very fragile and can not successfully hold the anchors. In this report, we propose a new application of light-curing dental resins for mounting base of electrodes or microdialysis probes in chronic experiments. This material allows direct bonding to the cranium. Therefore, anchor screws are not required and surgical field can be reduced considerably. Past experiences show that the bonding effect maintains more than 2 months. Conventional resin's window of time when the materials are pliable and workable is a few minutes. However, the window of working time for these dental adhesives is significantly wider and adjustable. PMID:18997897

Solid expellant plasma generator

NASA Technical Reports Server (NTRS)

Stone, Nobie H. (Inventor); Poe, Garrett D. (Inventor); Rood, Robert (Inventor)

2010-01-01

An improved solid expellant plasma generator has been developed. The plasma generator includes a support housing, an electrode rod located in the central portion of the housing, and a mass of solid expellant material that surrounds the electrode rod within the support housing. The electrode rod and the solid expellant material are made of separate materials that are selected so that the electrode and the solid expellant material decompose at the same rate when the plasma generator is ignited. This maintains a point of discharge of the plasma at the interface between the electrode and the solid expellant material.

Composite electrode for use in electrochemical cells

DOEpatents

Vanderborgh, N.E.; Huff, J.R.; Leddy, J.

1987-10-16

A porous composite electrode for use in electrochemical cells. The electrode has a first face and a second face defining a relatively thin section therebetween. The electrode is comprised of an ion conducting material, an electron conducting material, and an electrocatalyst. The volume concentration of the ion conducting material is greatest at the first face and is decreased across the section, while the volume concentration of the electron conducting material is greatest at the second face and decreases across the section of the electrode. Substantially all of the electrocatalyst is positioned within the electrode section in a relatively narrow zone where the rate of electron transport of the electrode is approximately equal to the rate of ion transport of the electrode. 4 figs., 1 tab.

Composite electrode for use in electrochemical cells

DOEpatents

Vanderborgh, Nicholas E.; Huff, James R.; Leddy, Johna

1989-01-01

A porous composite electrode for use in electrochemical cells. The electrode has a first face and a second face defining a relatively thin section therebetween. The electrode is comprised of an ion conducting material, an electron conducting material, and an electrocatalyst. The volume concentration of the ion conducting material is greatest at the first face and is decreased across the section, while the volume concentration of the electron conducting material is greatest at the second face and decreases across the section of the electrode. Substantially all of the electrocatalyst is positioned within the electrode section in a relatively narrow zone where the rate of electron transport of the electrode is approximately equal to the rate of ion transport of the electrode.

Assessment of capacitor electrodes for intracortical neural stimulation.

PubMed

Rose, T L; Kelliher, E M; Robblee, L S

1985-01-01

Capacitor electrodes offer the potential for the safest method of stimulation of neural tissue because they operate without any faradaic process occurring at the electrode-electrolyte interface. Their use eliminates problems associated with metal dissolution or water electrolysis which may occur with electrodes of noble metals. This paper reviews recent work aimed at increasing the charge storage density of capacitor electrodes to allow their application with the small areas of 10(-4) mm2 required for intracortical stimulation of single neurons. Increased charge storage with electrodes using anodic films such as TiO2 and Ta2O5 has been obtained by increasing the real surface area of microelectrodes. Experiments have also been done with BaTiO3 films which have a much higher dielectric constant than the anodic film dielectrics. State-of-the-art electrodes made with these materials, however, have a charge storage density which at best is comparable to that obtained with Pt and is considerably lower than electrochemically safe charge densities that have been reported for activated Ir. It is concluded that for very small intracortical electrodes, capacitor electrodes will not be competitive with electrodes which operate using surface localized faradaic reactions.

Investigations of Effect of Rotary EDM Electrode on Machining Performance of Al6061 Alloy

NASA Astrophysics Data System (ADS)

Robinson Smart, D. S.; Jenish Smart, Joses; Periasamy, C.; Ratna Kumar, P. S. Samuel

2018-04-01

Electric Discharge Machining is an essential process which is being used for machining desired shape using electrical discharges which creates sparks. There will be electrodes subjected to electric voltage and which are separated by a dielectric liquid. Removing of material will be due to the continuous and rapid current discharges between two electrodes.. The spark is very carefully controlled and localized so that it only affects the surface of the material. Usually in order to prevent the defects which are arising due to the conventional machining, the Electric Discharge Machining (EDM) machining is preferred. Also intricate and complicated shapes can be machined effectively by use of Electric Discharge Machining (EDM). The EDM process usually does not affect the heat treat below the surface. This research work focus on the design and fabrication of rotary EDM tool for machining Al6061alloy and investigation of effect of rotary tool on surface finish, material removal rate and tool wear rate. Also the effect of machining parameters of EDM such as pulse on & off time, current on material Removal Rate (MRR), Surface Roughness (SR) and Electrode wear rate (EWR) have studied. Al6061 alloy can be used for marine and offshore applications by reinforcing some other elements. The investigations have revealed that MRR (material removal rate), surface roughness (Ra) have been improved with the reduction in the tool wear rate (TWR) when the tool is rotating instead of stationary. It was clear that as rotary speed of the tool is increasing the material removal rate is increasing with the reduction of surface finish and tool wear rate.

Electrochemical Evaluations of Fractal Microelectrodes for Energy Efficient Neurostimulation.

PubMed

Park, Hyunsu; Takmakov, Pavel; Lee, Hyowon

2018-03-12

Advancements in microfabrication has enabled manufacturing of microscopic neurostimulation electrodes with smaller footprint than ever possible. The smaller electrodes can potentially reduce tissue damage and allow better spatial resolution for neural stimulation. Although electrodes of any shape can easily be fabricated, substantial effort have been focused on identification and characterization of new materials and surface morphology for efficient charge injection, while maintaining simple circular or rectangular Euclidean electrode geometries. In this work we provide a systematic electrochemical evaluation of charge injection capacities of serpentine and fractal-shaped platinum microelectrodes and compare their performance with traditional circular microelectrodes. Our findings indicate that the increase in electrode perimeter leads to an increase in maximum charge injection capacity. Furthermore, we found that the electrode geometry can have even more significant impact on electrode performance than having a larger perimeter for a given surface area. The fractal-shaped microelectrodes, despite having smaller perimeter than other designs, demonstrated superior charge injection capacity. Our results suggest that electrode design can significantly affect both Faradaic and non-Faradaic electrochemical processes, which may be optimized to enable a more energy efficient design for neurostimulation.

Method of making a layered composite electrode/electrolyte

DOEpatents

Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

2005-01-25

An electrode/electrolyte structure is prepared by a plurality of methods. An unsintered (possibly bisque fired) moderately catalytic electronically-conductive or homogeneous mixed ionic electronic conductive electrode material is deposited on a layer composed of a sintered or unsintered ionically-conductive electrolyte material prior to being sintered. A layer of particulate electrode material is deposited on an unsintered ("green") layer of electrolyte material and the electrode and electrolyte layers are sintered simultaneously, sometimes referred to as "co-firing," under conditions suitable to fully densify the electrolyte while the electrode retains porosity. Or, the layer of particulate electrode material is deposited on a previously sintered layer of electrolyte, and then sintered. Subsequently, a catalytic material is added to the electrode structure by infiltration of an electrolcatalyst precursor (e.g., a metal salt such as a transition metal nitrate). This may be followed by low temperature firing to convert the precursor to catalyst. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in an ionic (electrochemical) device such as fuel cells and electrolytic gas separation systems.

Recirculating electric air filter

DOEpatents

Bergman, W.

1985-01-09

An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

PubMed

Hao, Zhibin; Wang, Guozhu; Li, Wenbin; Zhang, Junguo; Kan, Jiangming

2015-01-01

The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended.

Electrochemical cell having an alkali-metal-nitrate electrode

DOEpatents

Roche, M.F.; Preto, S.K.

1982-06-04

A power-producing secondary electrochemical cell includes a molten alkali metal as the negative-electrode material and a molten-nitrate salt as the positive-electrode material. The molten material in the respective electrodes are separated by a solid barrier of alkali-metal-ion conducting material. A typical cell includes active materials of molten sodium separated from molten sodium nitrate and other nitrates in mixture by a layer of sodium ..beta..'' alumina.

Performance of Multi Walled Carbon Nanotubes Grown on Conductive Substrates as Supercapacitors Electrodes using Organic and Ionic liquid electrolytes

NASA Astrophysics Data System (ADS)

Winchester, Andrew; Ghosh, Sujoy; Turner, Ben; Zhang, X. F.; Talapatra, Saikat

2012-02-01

In this work we will present the use of Multi Walled Carbon Nanotubes (MWNT) directly grown on inconel substrates via chemical vapor deposition, as electrode materials for electrochemical double layer capacitors (EDLC). The performance of the MWNT EDLC electrodes were investigated using two electrolytes, an organic electrolyte, tetraethylammonium tetrafluoroborate in propylene carbonate (Et4NBF4 in PC), and a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements to obtain values for the capacitance and internal resistance of these devices will be presented and compared.

Atmospheric pressure plasma processing of polymeric materials utilizing close proximity indirect exposure

DOEpatents

Paulauskas, Felix L.; Bonds, Truman

2016-09-20

A plasma treatment method that includes providing treatment chamber including an intermediate heating volume and an interior treatment volume. The interior treatment volume contains an electrode assembly for generating a plasma and the intermediate heating volume heats the interior treatment volume. A work piece is traversed through the treatment chamber. A process gas is introduced to the interior treatment volume of the treatment chamber. A plasma is formed with the electrode assembly from the process gas, wherein a reactive species of the plasma is accelerated towards the fiber tow by flow vortices produced in the interior treatment volume by the electrode assembly.

Bus electrode having same thermal expansion coefficient as crystalline silicon solar cell

NASA Astrophysics Data System (ADS)

Kato, T.; Morita, H.; Nakano, H.; Washida, H.; Onoe, A.; Inomata, K.; Mori, F.; Sugai, S.

1982-01-01

It is well known that the bus electrode plays a main role in series resistance of solar cells. Bus electrodes composed of bare leads, were investigated for which thermal expansion coefficients are less than those of the cell and which are coated with highly conducting metals. These leads exhibited the lower expansion coefficient than expected by empirical law, and the origins of these phenomena were explained. Work hardening effect on the expansion coefficient was then measured. Solar cell fabrication with these leads and rigid solders rationalized assembly processing. Cell characteristics proved to be excellent compared with conventional ones. Finally, lead costs were compared for various materials.

Voltammetric analysis of ordnance materials. Part 2: A portable digital voltammeter for use with a silver wire working electrode

NASA Astrophysics Data System (ADS)

Fine, D. A.; Reeve, D. A.; Dickus, R. A.

1984-12-01

An inexpensive, portable, digital voltammeter has been designed and built at NWC. The instrument is intended for use with a silver wire working electrode. The voltammeter was built in response to a need on the part of Navy facilities for the monitoring of effluent water from the carbon column cleanup process used to remove propyleneglycoldinitrate from Otto fuel waste water. The instrument may also be used for the monitoring of contaminants such as nitroglycerin, dinitrotoluene, trinitrotoluene and nitroguanidine. This report describes in detail the construction, circuitry, software and operational features of the instrument.

All dispenser printed flexible 3D structured thermoelectric generators

NASA Astrophysics Data System (ADS)

Cao, Z.; Shi, J. J.; Torah, R. N.; Tudor, M. J.; Beeby, S. P.

2015-12-01

This work presents a vertically fabricated 3D thermoelectric generator (TEG) by dispenser printing on flexible polyimide substrate. This direct-write technology only involves printing of electrodes, thermoelectric active materials and structure material, which needs no masks to transfer the patterns onto the substrate. The dimension for single thermoelectric element is 2 mm × 2 mm × 0.5 mm while the distance between adjacent cubes is 1.2 mm. The polymer structure layer was used to support the electrodes which are printed to connect the top ends of the thermoelectric material and ensure the flexibility as well. The advantages and the limitations of the dispenser printed 3D TEGs will also be evaluated in this paper. The proposed method is potential to be a low-cost and scalable fabrication solution for TEGs.

Work function measurements of copper nanoparticle intercalated polyaniline nanocomposite thin films

NASA Astrophysics Data System (ADS)

Patil, U. V.; Ramgir, Niranjan S.; Bhogale, A.; Debnath, A. K.; Muthe, K. P.; Gadkari, S. C.; Kothari, D. C.

2017-05-01

The nature of contact between the electrode and the sensing material plays a crucial role in governing the sensing mechanism. Thin films of polyaniline (PANI) and copper-polyaniline nanocomposite (NC) have been deposited at room temperatures by in-situ oxidative polymerization of aniline in the presence of Cu nanoparticles. For sensing applications a thin film Au (gold) ˜100 nm is deposited and used as a conducting electrode. To understand the nature of contact (i.e., ohmic or Schottky) the work function of the conducting polyaniline and nanocomposite films were measured using Kelvin Probe method. I-V characteristics of PANI and NC films investigated at room temperatures further corroborates and confirms the formation of Ohmic contact as evident from work function measurements.

Covalent bonding of YIGSR and RGD to PEDOT/PSS/MWCNT-COOH composite material to improve the neural interface.

PubMed

Wang, Kun; Tang, Rong-Yu; Zhao, Xiao-Bo; Li, Jun-Jie; Lang, Yi-Ran; Jiang, Xiao-Xia; Sun, Hong-Ji; Lin, Qiu-Xia; Wang, Chang-Yong

2015-11-28

The development of coating materials for neural interfaces has been a pursued to improve the electrical, mechanical and biological performances. For these goals, a bioactive coating was developed in this work featuring a poly(3,4-ethylenedioxythiophene) (PEDOT)/carbon nanotube (CNT) composite and covalently bonded YIGSR and RGD. Its biological effect and electrical characteristics were assessed in vivo on microwire arrays (MWA). The coated electrodes exhibited a significantly higher charge storage capacity (CSC) and lower electrochemical impedance at 1 kHz which are desired to improve the stimulating and recording performances, respectively. Acute neural recording experiments revealed that coated MWA possess a higher signal/noise ratio capturing spikes undetected by uncoated electrodes. Moreover, coated MWA possessed more active sites and single units, and the noise floor of coated electrodes was lower than that of uncoated electrodes. There is little information in the literature concerning the chronic performance of bioactively modified neural interfaces in vivo. Therefore in this work, chronic in vivo tests were conducted and the PEDOT/PSS/MWCNT-polypeptide coated arrays exhibited excellent performances with the highest mean maximal amplitude from day 4 to day 12 during which the acute response severely compromised the performance of the electrodes. In brief, we developed a simple method of covalently bonding YIGSR and RGD to a PEDOT/PSS/MWCNT-COOH composite improving both the biocompatibility and electrical performance of the neural interface. Our findings suggest that YIGSR and RGD modified PEDOT/PSS/MWCNT is a promising bioactivated composite coating for neural recording and stimulating.

Method for starting operation of a resistance melter

DOEpatents

Chapman, Christopher Charles

1977-01-01

A method for starting the operation of a resistance furnace, where heating occurs by passing a current through the charge between two furnace electrodes and the charge is a material which is essentially electrically nonconductive when in a solid physical state but which becomes more electrically conductive when in a molten physical state, by connecting electrical resistance heating wire between the furnace electrodes, placing the wire in contact with the charge material between the electrodes and passing a current through the wire to heat the wire to a temperature sufficient to melt the material between the furnace electrodes so that as the material melts, current begins to pass between the electrodes through the melted material, further heating and melting more material until all current between the electrodes passes through the charge material without the aid or presence of the resistance element.

Electrode-active material for electrochemical batteries and method of preparation

DOEpatents

Varma, R.

1983-11-07

A battery electrode material comprises a non-stoichiometric electrode-active material which forms a redox pair with the battery electrolyte, an electrically conductive polymer present in the range of from about 2% by weight to about 5% by weight of the electrode-active material, and a binder. The conductive polymer provides improved proton or ion conductivity and is a ligand resulting in metal ion or negative ion vacancies of less than about 0.1 atom percent. Specific electrodes of nickel and lead are disclosed.

Electrode-active material for electrochemical batteries and method of preparation

DOEpatents

Varma, Ravi

1987-01-01

A battery electrode material comprising a non-stoichiometric electrode-active material which forms a redox pair with the battery electrolyte, an electrically conductive polymer present in the range of from about 2% by weight to about 5% by weight of the electrode-active material, and a binder. The conductive polymer provides improved proton or ion conductivity and is a ligand resulting in metal ion or negative ion vacancies of less than about 0.1 atom percent. Specific electrodes of nickel and lead are disclosed.

Monte Carlo modelling the dosimetric effects of electrode material on diamond detectors.

PubMed

Baluti, Florentina; Deloar, Hossain M; Lansley, Stuart P; Meyer, Juergen

2015-03-01

Diamond detectors for radiation dosimetry were modelled using the EGSnrc Monte Carlo code to investigate the influence of electrode material and detector orientation on the absorbed dose. The small dimensions of the electrode/diamond/electrode detector structure required very thin voxels and the use of non-standard DOSXYZnrc Monte Carlo model parameters. The interface phenomena was investigated by simulating a 6 MV beam and detectors with different electrode materials, namely Al, Ag, Cu and Au, with thickens of 0.1 µm for the electrodes and 0.1 mm for the diamond, in both perpendicular and parallel detector orientation with regards to the incident beam. The smallest perturbations were observed for the parallel detector orientation and Al electrodes (Z = 13). In summary, EGSnrc Monte Carlo code is well suited for modelling small detector geometries. The Monte Carlo model developed is a useful tool to investigate the dosimetric effects caused by different electrode materials. To minimise perturbations cause by the detector electrodes, it is recommended that the electrodes should be made from a low-atomic number material and placed parallel to the beam direction.

Development of an Eco-Friendly Electrical Discharge Machine (E-EDM) Using TRIZ Approach

NASA Astrophysics Data System (ADS)

Sreebalaji, V. S.; Saravanan, R.

Electrical Discharge Machine (EDM) is one of the non-traditional machining processes. EDM process is based on thermoelectric energy between the work and an electrode. A pulse discharge occurs in a small gap between the work piece and the electrode and removes the unwanted material from the parent metal through melting and vaporization. The electrode and the work piece must have an electrical conductivity in order to generate the spark. Dielectric fluid acts as a spark conductor, concentrating the energy to a very narrow region. There are various types of products can be produced and finished using EDM such as Moulds, Dies, Parts of Aerodynamics, Automotives and Surgical components. This research work reveals how an Eco friendly EDM (E-EDM) can be modeled to replace die electric fluid and introducing ozonised oxygen in to EDM to eliminate harmful effects generated while machining by using dielectric, to make pollution free machining environment through a new design of EEDM using TRIZ (a Russian acronym for Theory of Inventive Problem Solving) approach, since Eco friendly design is the need of the hour.

High-performance single CdS nanowire (nanobelt) Schottky junction solar cells with Au/graphene Schottky electrodes.

PubMed

Ye, Yu; Dai, Yu; Dai, Lun; Shi, Zujin; Liu, Nan; Wang, Fei; Fu, Lei; Peng, Ruomin; Wen, Xiaonan; Chen, Zhijian; Liu, Zhongfan; Qin, Guogang

2010-12-01

High-performance single CdS nanowire (NW) as well as nanobelt (NB) Schottky junction solar cells were fabricated. Au (5 nm)/graphene combined layers were used as the Schottky contact electrodes to the NWs (NBs). Typical as-fabricated NW solar cell shows excellent photovoltaic behavior with an open circuit voltage of ∼0.15 V, a short circuit current of ∼275.0 pA, and an energy conversion efficiency of up to ∼1.65%. The physical mechanism of the combined Schottky electrode was discussed. We attribute the prominent capability of the devices to the high-performance Schottky combined electrode, which has the merits of low series resistance, high transparency, and good Schottky contact to the CdS NW (NB). Besides, a promising site-controllable patterned graphene transfer method, which has the advantages of economizing graphene material and free from additional etching process, was demonstrated in this work. Our results suggest that semiconductor NWs (NBs) are promising materials for novel solar cells, which have potential application in integrated nano-optoelectronic systems.

Alternate electrode materials for the SP100 reactor

NASA Astrophysics Data System (ADS)

Randich, E.

1992-05-01

This work was performed in response to a request by the Astro-Space Division of the General Electric Co. to develop alternate electrodes materials for the electrodes of the PD2 modules to be used in the SP100 thermoelectric power conversion system. Initially, the project consisted of four tasks: (1) development of a ZrB2 (C) CVD coating on SiMo substrates; (2) development of a ZrB2 (C) CVD coating on SiGe substrates; (3) development of CVI W for porous graphite electrodes; and (4) technology transfer of pertinent developed processes. The project evolved initially into developing only ZrB2 coatings on SiGe and graphite substrates, and later into developing ZrB2 coatings only on graphite substrates. Several sizes of graphite and pyrolytic carbon-coated graphite substrates were coated with ZrB2 during the project. For budgetary reasons, the project was terminated after half the allotted time had passed. Apart from the production of coated specimens for evaluation, the major accomplishment of the project was the development of the CVD processing to produce the desired coatings.

Evaluating the Field Emission Characteristics of Aluminum for DC High Voltage Photo-Electron Guns

NASA Astrophysics Data System (ADS)

Taus, Rhys; Poelker, Matthew; Forman, Eric; Mamun, Abdullah

2014-03-01

High current photoguns require high power laser light, but only a small portion of the laser light illuminating the photocathode produces electron beam. Most of the laser light (~ 65%) simply serves to heat the photocathode, which leads to evaporation of the chemicals required to create the negative electron affinity condition necessary for photoemission. Photocathode cooling techniques have been employed to address this problem, but active cooling of the photocathode is complicated because the cooling apparatus must float at high voltage. This work evaluates the field emission characteristics of cathode electrodes manufactured from materials with high thermal conductivity: aluminum and copper. These electrodes could serve as effective heat sinks, to passively cool the photocathode that resides within such a structure. However, literature suggests ``soft'' materials like aluminum and copper are ill suited for photogun applications, due to excessive field emission when biased at high voltage. This work provides an evaluation of aluminum and copper electrodes inside a high voltage field emission test stand, before and after coating with titanium nitride (TiN), a coating that enhances surface hardness. National Science Foundation Award Number: 1062320 and the Department of Defence ASSURE program.

Utilizing Waste Thermocol Sheets and Rusted Iron Wires to Fabricate Carbon-Fe3O4 Nanocomposite Based Supercapacitors: Turning Wastes into Value-Added Materials.

PubMed

Vadiyar, Madagonda M; Liu, Xudong; Ye, Zhibin

2018-05-14

In the present work, we demonstrate the synthesis of porous activated carbon (specific surface area, 1,883 m2 g-1), Fe3O4 nanoparticles, and carbon-Fe3O4 nanocomposites using local waste thermocol sheets and rusted iron wires. The resulting carbon, Fe3O4 nanoparticles, and carbon-Fe3O4 composites are used as electrode materials for supercapacitor application. In particular, C-Fe3O4 composite electrodes exhibit a high specific capacitance of 1,375 F g-1 at 1 A g-1 and longer cyclic stability with 98 % of capacitance retention over 10,000 cycles. Subsequently, asymmetric supercapacitor, i. e., C-Fe3O4//Ni(OH)2/CNT device exhibits a high energy density of 91.1 Wh kg-1 and a remarkable cyclic stability, showing 98% of capacitance retention over 10,000 cycles. Thus, this work has important implications not only for the fabrication of low-cost electrodes for high-performance supercapacitors but also for the recycling of waste thermocol sheets and rust iron wires for value-added reuse. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile Synthesis of Flower-Like Copper-Cobalt Sulfide as Binder-Free Faradaic Electrodes for Supercapacitors with Improved Electrochemical Properties

PubMed Central

Wang, Tianlei; Liu, Meitang; Ma, Hongwen

2017-01-01

Supercapacitors have been one of the highest potential candidates for energy storage because of their significant advantages beyond rechargeable batteries in terms of large power density, short recharging time, and long cycle lifespan. In this work, Cu–Co sulfides with uniform flower-like structure have been successfully obtained via a traditional two-step hydrothermal method. The as-fabricated Cu–Co sulfide vulcanized from precursor (P–Cu–Co sulfide) is able to deliver superior specific capacitance of 592 F g−1 at 1 A g−1 and 518 F g−1 at 10 A g−1 which are surprisingly about 1.44 times and 2.39 times higher than those of Cu–Co oxide electrode, respectively. At the same time, excellent cycling stability of P–Cu–Co sulfide is indicated by 90.4% capacitance retention at high current density of 10 A g−1 after 3000 cycles. Because of the introduction of sulfur during the vulcanization process, these new developed sulfides can get more flexible structure and larger reaction surface area, and will own richer redox reaction sites between the interfaces of active material/electrolyte. The uniform flower-like P–Cu–Co sulfide electrode materials will have more potential alternatives for oxides electrode materials in the future. PMID:28590417

One-step synthesis of Nickle Iron-layered double hydroxide/reduced graphene oxide/carbon nanofibres composite as electrode materials for asymmetric supercapacitor.

PubMed

Wang, Feifei; Wang, Ting; Sun, Shiguo; Xu, Yongqian; Yu, Ruijin; Li, Hongjuan

2018-06-11

A novel NiFe-LDH/RGO/CNFs composite was produced by using a facile one-step hydrothermal method as electrode for supercapacitor. Compared with NiFe-LDH/CNFs, NiFe-LDH/CNTs and NiFe-LDH/RGO, NiFe-LDH/RGO/CNFs demonstrated a high specific capacitance of 1330.2 F g -1 at 1 A g -1 and a super rate capability of 64.2% from 1 to 20 A g -1 , indicating great potential for supercapacitor application. Additionally, an asymmetric supercapacitor using NiFe-LDH/RGO/CNFs composite as positive electrode material and activated carbon as negative electrode material was assembled. The asymmetric supercapacitor can work in the voltage range of 0-1.57 V. It displayed high energy density of 33.7 W h kg -1 at power density of 785.8 W kg -1 and excellent cycling stability with 97.1% of the initial capacitance after 2500 cycles at 8 A g -1 . Two flexible AC//LDH-RGO-CNFs ASC devices connected in series were able to light up a red LED indicator after being fully charged. The results demonstrate that the AC//LDH-RGO-CNFs ASC has a promising potential in commercial application.

Porous, Hyper-cross-linked, Three-Dimensional Polymer as Stable, High Rate Capability Electrode for Lithium-Ion Battery.

PubMed

Mukherjee, Debdyuti; Gowda Y K, Guruprasada; Makri Nimbegondi Kotresh, Harish; Sampath, S

2017-06-14

Organic materials containing active carbonyl groups have attracted considerable attention as electrodes in Li-ion batteries due to their reversible redox activity, ability to retain capacity, and, in addition, their ecofriendly nature. Introduction of porosity will help accommodate as well as store small ions and molecules reversibly. In the present work, we introduce a mesoporous triptycene-related, rigid network polymer with high specific surface area as an electrode material for rechargeable Li-ion battery. The designed polymer with a three-dimensional (3D), rigid porous network allows free movement of ions/electrolyte as well as helps in interacting with the active anhydride moieties (containing two carbonyl groups). Considerable intake of Li + ions giving rise to very high specific capacity of 1100 mA h g -1 at a discharge current of 50 mA g -1 and ∼120 mA h g -1 at a high discharge current of 3 A g -1 are observed with excellent cyclability up to 1000 cycles. This remarkable rate capability, which is one of the highest among the reported organic porous polymers to date, makes the triptycene-related rigid 3D network a very good choice for Li-ion batteries and opens up a new method to design polymer-based electrode materials for metal-ion battery technology.

Facile Synthesis of Flower-Like Copper-Cobalt Sulfide as Binder-Free Faradaic Electrodes for Supercapacitors with Improved Electrochemical Properties.

PubMed

Wang, Tianlei; Liu, Meitang; Ma, Hongwen

2017-06-07

Supercapacitors have been one of the highest potential candidates for energy storage because of their significant advantages beyond rechargeable batteries in terms of large power density, short recharging time, and long cycle lifespan. In this work, Cu-Co sulfides with uniform flower-like structure have been successfully obtained via a traditional two-step hydrothermal method. The as-fabricated Cu-Co sulfide vulcanized from precursor (P-Cu-Co sulfide) is able to deliver superior specific capacitance of 592 F g -1 at 1 A g -1 and 518 F g -1 at 10 A g -1 which are surprisingly about 1.44 times and 2.39 times higher than those of Cu-Co oxide electrode, respectively. At the same time, excellent cycling stability of P-Cu-Co sulfide is indicated by 90.4% capacitance retention at high current density of 10 A g -1 after 3000 cycles. Because of the introduction of sulfur during the vulcanization process, these new developed sulfides can get more flexible structure and larger reaction surface area, and will own richer redox reaction sites between the interfaces of active material/electrolyte. The uniform flower-like P-Cu-Co sulfide electrode materials will have more potential alternatives for oxides electrode materials in the future.

Electrode/workpiece combinations

NASA Astrophysics Data System (ADS)

Benedict, J. J.

1989-10-01

Of the many machine tool operations available in the shop today, plunge cut Electrical Discharge Machining (EDM) has become an increasingly useful method of materials fabrication. It is a necessary tool for the research and development type of work performed at the Lawrence Livermore National Laboratory (LLNL). With advancing technology, plunge cut EDMs are more efficient, faster, have greater accuracy and are able to produce better surface finishes. They have been in the past and will continue to be an important part of the production of quality parts in both the Precision and NC Shop. It should be kept in mind that as a non-traditional machining process, EDMing is a time consuming process that can be a very expensive method of producing parts. For this reason, it must be used in the most efficient manner in order to make it a cost-effective means of fabrication, although technology has advanced to the point of state-of-the-art equipment, there is currently a void in available technical information needed for use with this process. The type of information sought after concerns the area of electrode/workpiece combinations. This is in reference to the task of choosing the correct electrode material for the specific workpiece material encountered. A brief description of the EDM process will help in understanding the electrode/workpiece relationship.

Surface-Embedded Stretchable Electrodes by Direct Printing and their Uses to Fabricate Ultrathin Vibration Sensors and Circuits for 3D Structures.

PubMed

Song, Jun Hyuk; Kim, Young-Tae; Cho, Sunghwan; Song, Woo-Jin; Moon, Sungmin; Park, Chan-Gyung; Park, Soojin; Myoung, Jae Min; Jeong, Unyong

2017-11-01

Printing is one of the easy and quick ways to make a stretchable wearable electronics. Conventional printing methods deposit conductive materials "on" or "inside" a rubber substrate. The conductors made by such printing methods cannot be used as device electrodes because of the large surface topology, poor stretchability, or weak adhesion between the substrate and the conducting material. Here, a method is presented by which conductive materials are printed in the way of being surface-embedded in the rubber substrate; hence, the conductors can be widely used as device electrodes and circuits. The printing process involves a direct printing of a metal precursor solution in a block-copolymer rubber substrate and chemical reduction of the precursor into metal nanoparticles. The electrical conductivity and sensitivity to the mechanical deformation can be controlled by adjusting the number of printing operations. The fabrication of highly sensitive vibration sensors is thus presented, which can detect weak pulses and sound waves. In addition, this work takes advantage of the viscoelasticity of the composite conductor to fabricate highly conductive stretchable circuits for complicated 3D structures. The printed electrodes are also used to fabricate a stretchable electrochemiluminescence display. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toward greener lithium-ion batteries: Aqueous binder-based LiNi0.4Co0.2Mn0.4O2 cathode material with superior electrochemical performance

NASA Astrophysics Data System (ADS)

Chen, Zhen; Kim, Guk-Tae; Chao, Dongliang; Loeffler, Nicholas; Copley, Mark; Lin, Jianyi; Shen, Zexiang; Passerini, Stefano

2017-12-01

This work reports the performance of LiNi0.4Co0.2Mn0.4O2 electrodes employing sodium carboxymethyl cellulose as the binder (CMC/NCM). Compared with conventional organic PVDF-based electrodes, the CMC/NCM electrodes display very uniform distribution of NCM and carbon particles together with strong adhesion among the particles and with the current collector, leading to significantly mitigated crack formation and delamination of the electrode upon repeated delithiation/lithiation processes. Additionally, these electrodes offer enhanced Li+ diffusion kinetics, reduced polarization, therefore, excellent high C-rate capability, and extremely stable cycling performance even at elevated temperature (60 °C). Benefiting from the features of low cost, environmentally friendliness, and easy disposability-recyclability, the water-soluble CMC is a promising binder for practical application in energy storage systems.

Stacked 3D RRAM Array with Graphene/CNT as Edge Electrodes

PubMed Central

Bai, Yue; Wu, Huaqiang; Wang, Kun; Wu, Riga; Song, Lin; Li, Tianyi; Wang, Jiangtao; Yu, Zhiping; Qian, He

2015-01-01

There are two critical challenges which determine the array density of 3D RRAM: 1) the scaling limit in both horizontal and vertical directions; 2) the integration of selector devices in 3D structure. In this work, we present a novel 3D RRAM structure using low-dimensional materials, including 2D graphene and 1D carbon nanotube (CNT), as the edge electrodes. A two-layer 3D RRAM with monolayer graphene as edge electrode is demonstrated. The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale. Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized. Furthermore, the discussion of high array density potential is presented. PMID:26348797

Stacked 3D RRAM Array with Graphene/CNT as Edge Electrodes.

PubMed

Bai, Yue; Wu, Huaqiang; Wang, Kun; Wu, Riga; Song, Lin; Li, Tianyi; Wang, Jiangtao; Yu, Zhiping; Qian, He

2015-09-08

There are two critical challenges which determine the array density of 3D RRAM: 1) the scaling limit in both horizontal and vertical directions; 2) the integration of selector devices in 3D structure. In this work, we present a novel 3D RRAM structure using low-dimensional materials, including 2D graphene and 1D carbon nanotube (CNT), as the edge electrodes. A two-layer 3D RRAM with monolayer graphene as edge electrode is demonstrated. The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale. Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized. Furthermore, the discussion of high array density potential is presented.

Modeling, design, packing and experimental analysis of liquid-phase shear-horizontal surface acoustic wave sensors

NASA Astrophysics Data System (ADS)

Pollard, Thomas B

Recent advances in microbiology, computational capabilities, and microelectromechanical-system fabrication techniques permit modeling, design, and fabrication of low-cost, miniature, sensitive and selective liquid-phase sensors and lab-on-a-chip systems. Such devices are expected to replace expensive, time-consuming, and bulky laboratory-based testing equipment. Potential applications for devices include: fluid characterization for material science and industry; chemical analysis in medicine and pharmacology; study of biological processes; food analysis; chemical kinetics analysis; and environmental monitoring. When combined with liquid-phase packaging, sensors based on surface-acoustic-wave (SAW) technology are considered strong candidates. For this reason such devices are focused on in this work; emphasis placed on device modeling and packaging for liquid-phase operation. Regarding modeling, topics considered include mode excitation efficiency of transducers; mode sensitivity based on guiding structure materials/geometries; and use of new piezoelectric materials. On packaging, topics considered include package interfacing with SAW devices, and minimization of packaging effects on device performance. In this work novel numerical models are theoretically developed and implemented to study propagation and transduction characteristics of sensor designs using wave/constitutive equations, Green's functions, and boundary/finite element methods. Using developed simulation tools that consider finite-thickness of all device electrodes, transduction efficiency for SAW transducers with neighboring uniform or periodic guiding electrodes is reported for the first time. Results indicate finite electrode thickness strongly affects efficiency. Using dense electrodes, efficiency is shown to approach 92% and 100% for uniform and periodic electrode guiding, respectively; yielding improved sensor detection limits. A numerical sensitivity analysis is presented targeting viscosity using uniform-electrode and shear-horizontal mode configurations on potassium-niobate, langasite, and quartz substrates. Optimum configurations are determined yielding maximum sensitivity. Results show mode propagation-loss and sensitivity to viscosity are correlated by a factor independent of substrate material. The analysis is useful for designing devices meeting sensitivity and signal level requirements. A novel, rapid and precise microfluidic chamber alignment/bonding method was developed for SAW platforms. The package is shown to have little effect on device performance and permits simple macrofluidic interfacing. Lastly, prototypes were designed, fabricated, and tested for viscosity and biosensor applications; results show ability to detect as low as 1% glycerol in water and surface-bound DNA crosslinking.

Improving Electrode Durability of PEF Chamber by selecting suitable material

USDA-ARS?s Scientific Manuscript database

Corrosion resistance of four materials - titanium, platinized titanium, stainless steel, and boron carbide - as electrodes in a Pulsed Electric Field (PEF) system was studied to reduce electrode material migration into the food by electrode corrosion. The PEF process conditions were 28 kV/cm field s...

Composite electrodes for advanced electrochemical applications. Quarterly report for the period October 1, - December 31, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovach, Chris

The electrochemical industry is one of the most highly energy intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating costs, and the proprietary nature of the technology. In addition, DSAs experience problems that include: contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from underattack,more » generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.« less

Composite electrodes for advanced electrochemical applications. Quarterly report for the period July 1 - September 30, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovach, Chris

The electrochemical industry is one of the most highly energy-intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating cost, and the proprietary nature of the technology. In addition, DSAs experience problems that include contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from under attack,more » generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy-efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.« less

A study of room-temperature LixMn1.5Ni0.5O4 solid solutions

NASA Astrophysics Data System (ADS)

Saravanan, Kuppan; Jarry, Angelique; Kostecki, Robert; Chen, Guoying

2015-01-01

Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature LixMn1.5Ni0.5O4 solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of LixMn1.5Ni0.5O4 (0 <= x <= 1) cathode material consisting of three cubic phases: LiMn1.5Ni0.5O4 (Phase I), Li0.5Mn1.5Ni0.5O4 (Phase II) and Mn1.5Ni0.5O4 (Phase III). A phase diagram capturing the structural changes as functions of both temperature and Li content was established. The work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance.

Photoelectrochemistry of III-V epitaxial layers and nanowires for solar energy conversion

NASA Astrophysics Data System (ADS)

Parameshwaran, Vijay; Enck, Ryan; Chung, Roy; Kelley, Stephen; Sampath, Anand; Reed, Meredith; Xu, Xiaoqing; Clemens, Bruce

2017-05-01

III-V materials, which exhibit high absorption coefficients and charge carrier mobility, are ideal templates for solar energy conversion applications. This work describes the photoelectrochemistry research in several IIIV/electrolyte junctions as an enabler for device design for solar chemical reactions. By designing lattice-matched epitaxial growth of InGaP and GaP on GaAs and Si, respectively, extended depletion region electrodes achieve photovoltages which provide an additional boost to the underlying substrate photovoltage. The InGaP/GaAs and GaP/Si electrodes drive hydrogen evolution currents under aqueous conditions. By using nanowires of InN and InP under carefully controlled growth conditions, current and capacitance measurements are obtained to reveal the nature of the nanowire-electrolyte interface and how light is translated into photocurrent for InP and a photovoltage in InN. The materials system is expanded into the III-V nitride semiconductors, in which it is shown that varying the morphology of GaN on silicon yields insights to how the interface and light conversion is modulated as a basis for future designs. Current extensions of this work address growth and tuning of the III-V nitride electrodes with doping and polarization engineering for efficient coupling to solar-driven chemical reactions, and rapid-throughput methods for III-V nanomaterials synthesis in this materials space.

Compressive Sensing Cluster Expansion Studies of Lithium Intercalation and Phase Transformation in MoS2 for Energy Storage

NASA Astrophysics Data System (ADS)

Liu, Chi-Ping; Zhou, Fei; Ozolins, Vidvuds; University of California, Los Angeles Collaboration; Lawrence livermore national laboratory Collaboration

2015-03-01

Bulk molybdenum disulfide (MoS2) is a good electrode material candidate for energy storage applications, such as lithium ion batteries and supercapacitors due to its high theoretical energy and power density. First-principles density-functional theory (DFT) calculations combined with cluster expansion are an effective method to study thermodynamic and kinetic properties of electrode materials. In order to construct accurate models for cluster expansion, it is important to effectively choose clusters with significant contributions. In this work, we employ a compressive sensing based technique to select relevant clusters in order to build an accurate Hamiltonian for cluster expansion, enabling the study of Li intercalation in MoS2. We find that the 2H MoS2 structure is only stable at low Li content while 1T MoS2 is the preferred phase at high Li content. The results show that the 2H MoS2 phase transforms into the disordered 1T phase and the disordered 1T structure remains after the first Li insertion/deinsertion cycle suggesting that disordered 1T MoS2 is stable even at dilute Li content. This work also highlights that cluster expansion treated with compressive sensing is an effective and powerful tool for model construction and can be applied to advanced battery and supercapacitor electrode materials.

CMOS compatible electrode materials selection in oxide-based memory devices

NASA Astrophysics Data System (ADS)

Zhuo, V. Y.-Q.; Li, M.; Guo, Y.; Wang, W.; Yang, Y.; Jiang, Y.; Robertson, J.

2016-07-01

Electrode materials selection guidelines for oxide-based memory devices are constructed from the combined knowledge of observed device operation characteristics, ab-initio calculations, and nano-material characterization. It is demonstrated that changing the top electrode material from Ge to Cr to Ta in the Ta2O5-based memory devices resulted in a reduction of the operation voltages and current. Energy Dispersed X-ray (EDX) Spectrometer analysis clearly shows that the different top electrode materials scavenge oxygen ions from the Ta2O5 memory layer at various degrees, leading to different oxygen vacancy concentrations within the Ta2O5, thus the observed trends in the device performance. Replacing the Pt bottom electrode material with CMOS compatible materials (Ru and Ir) further reduces the power consumption and can be attributed to the modification of the Schottky barrier height and oxygen vacancy concentration at the electrode/oxide interface. Both trends in the device performance and EDX results are corroborated by the ab-initio calculations which reveal that the electrode material tunes the oxygen vacancy concentration via the oxygen chemical potential and defect formation energy. This experimental-theoretical approach strongly suggests that the proper selection of CMOS compatible electrode materials will create the critical oxygen vacancy concentration to attain low power memory performance.

Insights into the Surface Reactivity of Cermet and Perovskite Electrodes in Oxidizing, Reducing, and Humid Environments.

PubMed

Paloukis, Fotios; Papazisi, Kalliopi M; Dintzer, Thierry; Papaefthimiou, Vasiliki; Saveleva, Viktoriia A; Balomenou, Stella P; Tsiplakides, Dimitrios; Bournel, Fabrice; Gallet, Jean-Jacques; Zafeiratos, Spyridon

2017-08-02

Understanding the surface chemistry of electrode materials under gas environments is important in order to control their performance during electrochemical and catalytic applications. This work compares the surface reactivity of Ni/YSZ and La 0.75 Sr 0.25 Cr 0.9 Fe 0.1 O 3 , which are commonly used types of electrodes in solid oxide electrochemical devices. In situ synchrotron-based near-ambient pressure photoemission and absorption spectroscopy experiments, assisted by theoretical spectral simulations and combined with microscopy and electrochemical measurements, are used to monitor the effect of the gas atmosphere on the chemical state, the morphology, and the electrical conductivity of the electrodes. It is shown that the surface of both electrode types readjusts fast to the reactive gas atmosphere and their surface composition is notably modified. In the case of Ni/YSZ, this is followed by evident changes in the oxidation state of nickel, while for La 0.75 Sr 0.25 Cr 0.9 Fe 0.1 O 3 , a fine adjustment of the Cr valence and strong Sr segregation is observed. An important difference between the two electrodes is their capacity to maintain adsorbed hydroxyl groups on their surface, which is expected to be critical for the electrocatalytic properties of the materials. The insight gained from the surface analysis may serve as a paradigm for understanding the effect of the gas environment on the electrochemical performance and the electrical conductivity of the electrodes.

Thick electrodes including nanoparticles having electroactive materials and methods of making same

DOEpatents

Xiao, Jie; Lu, Dongping; Liu, Jun; Zhang, Jiguang; Graff, Gordon L.

2017-02-21

Electrodes having nanostructure and/or utilizing nanoparticles of active materials and having high mass loadings of the active materials can be made to be physically robust and free of cracks and pinholes. The electrodes include nanoparticles having electroactive material, which nanoparticles are aggregated with carbon into larger secondary particles. The secondary particles can be bound with a binder to form the electrode.

Creating 3D Hierarchical Carbon Architectures with Micro-, Meso-, and Macropores via a Simple Self-Blowing Strategy for a Flow-through Deionization Capacitor.

PubMed

Zhao, Shanshan; Yan, Tingting; Wang, Hui; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong

2016-07-20

In this work, 3D hierarchical carbon architectures (3DHCAs) with micro-, meso-, and macropores were prepared via a simple self-blowing strategy as highly efficient electrodes for a flow-through deionization capacitor (FTDC). The obtained 3DHCAs have a hierarchically porous structure, large accessible specific surface area (2061 m(2) g(-1)), and good wettability. The electrochemical tests show that the 3DHCA electrode has a high specific capacitance and good electric conductivity. The deionization experiments demonstrate that the 3DHCA electrodes possess a high deionization capacity of 17.83 mg g(-1) in a 500 mg L(-1) NaCl solution at 1.2 V. Moreover, the 3DHCA electrodes present a fast deionization rate in 100-500 mg L(-1) NaCl solutions at 0.8-1.4 V. The 3DHCA electrodes also present a good regeneration behavior in the reiterative regeneration test. These above factors render the 3DHCAs a promising FTDC electrode material.

Influence of electrode preparation on the electrochemical performance of LiNi0.8Co0.15Al0.05O2 composite electrodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Tran, Hai Yen; Greco, Giorgia; Täubert, Corina; Wohlfahrt-Mehrens, Margret; Haselrieder, Wolfgang; Kwade, Arno

2012-07-01

The electrode manufacturing for lithium-ion batteries is based on a complex process chain with several influencing factors. A proper tailoring of the electrodes can greatly improve both the electrochemical performances and the energy density of the battery. In the present work, some significant parameters during the preparation of LiNi0.8Co0.15Al0.05O2-based cathodes were investigated. The active material was mixed with a PVDF-binder and two conductive additives in different ratios. The electrode thickness, the degree of compacting and the conductive agent type and mixing ratio have proven to have a strong impact on the electrochemical performances of the composite electrodes, especially on their behaviour at high C-rates. Further it has been shown that the compacting has an essential influence on the mechanical properties of NCA coatings, according to their total, ductile and elastic deformation behaviour.

Monolithic quasi-solid-state dye-sensitized solar cells based on graphene-modified mesoscopic carbon-counter electrodes

NASA Astrophysics Data System (ADS)

Rong, Yaoguang; Han, Hongwei

2013-01-01

A monolithic quasi-solid-state dye-sensitized solar cell (DSSC) based on graphene-modified mesoscopic carbon-counter electrode is developed. A TiO2-working electrode layer, ZrO2 spacer layer, and carbon counter electrode layer were constructed on a single conducting glass substrate by screen printing. The quasi-solid-state polymer gel electrolyte employed a polymer composite as the gelator, and effectively infiltrated the porous layers. Fabricated with normal carbon-counter electrode (NC-CE) containing graphite and carbon black, the DSSC had a power conversion efficiency (PCE) of 5.09% with the fill factor of 0.63 at 100 mW cm-2 AM1.5 illumination. When the NC-CE was modified with graphene sheets, the PCE and fill factor were enhanced to 6.27% and 0.71, respectively. This improvement indicates excellent conductivity and high electrocatalytic activity of the graphene sheets, which have been considered as a promising platinum-free electrode material for DSSCs.

On the hydrophilicity of electrodes for capacitive energy extraction

NASA Astrophysics Data System (ADS)

Lian, Cheng; Kong, Xian; Liu, Honglai; Wu, Jianzhong

2016-11-01

The so-called Capmix technique for energy extraction is based on the cyclic expansion of electrical double layers to harvest dissipative energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the electrical potentials for the charging and discharging processes, which must be matched with the pore characteristics of the electrode materials. While a number of recent studies have examined the effects of the electrode pore size and geometry on the capacitive energy extraction processes, there is little knowledge on how the surface properties of the electrodes affect the thermodynamic efficiency. In this work, we investigate the Capmix processes using the classical density functional theory for a realistic model of electrolyte solutions. The theoretical predictions allow us to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different surface hydrophobicity. In agreement with recent experiments, we find that the thermodynamic efficiency can be much improved by using most hydrophilic electrodes.

Microbial Biofilm Voltammetry: Direct Electrochemical Characterization of Catalytic Electrode-Attached Biofilms▿ †

PubMed Central

Marsili, Enrico; Rollefson, Janet B.; Baron, Daniel B.; Hozalski, Raymond M.; Bond, Daniel R.

2008-01-01

While electrochemical characterization of enzymes immobilized on electrodes has become common, there is still a need for reliable quantitative methods for study of electron transfer between living cells and conductive surfaces. This work describes growth of thin (<20 μm) Geobacter sulfurreducens biofilms on polished glassy carbon electrodes, using stirred three-electrode anaerobic bioreactors controlled by potentiostats and nondestructive voltammetry techniques for characterization of viable biofilms. Routine in vivo analysis of electron transfer between bacterial cells and electrodes was performed, providing insight into the main redox-active species participating in electron transfer to electrodes. At low scan rates, cyclic voltammetry revealed catalytic electron transfer between cells and the electrode, similar to what has been observed for pure enzymes attached to electrodes under continuous turnover conditions. Differential pulse voltammetry and electrochemical impedance spectroscopy also revealed features that were consistent with electron transfer being mediated by an adsorbed catalyst. Multiple redox-active species were detected, revealing complexity at the outer surfaces of this bacterium. These techniques provide the basis for cataloging quantifiable, defined electron transfer phenotypes as a function of potential, electrode material, growth phase, and culture conditions and provide a framework for comparisons with other species or communities. PMID:18849456

Electro-Active Transducer Using Radial Electric Field To Produce/Motion Sense Out-Of-Plane Transducer

NASA Technical Reports Server (NTRS)

Bryant, Robert G. (Inventor); Fox, Robert L. (Inventor)

2006-01-01

An electro-active transducer includes a ferroelectric material sandwiched by first and second electrode patterns. When the device is used as an actuator, the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when voltage is applied to the electrode patterns. When the device is used as a sensor. the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when the ferroelectric material experiences deflection in a direction substantially perpendicular thereto. In each case, the electrode patterns are designed to cause the electric field to: i) originate at a region of the ferroelectric material between the first and second electrode patterns. and ii) extend radially outward from the region of the ferroelectric material (at which the electric field originates) and substantially parallel to the ferroelectric material s plane.

Development of a semigraphitic sulfur-doped ordered mesoporous carbon material for electroanalytical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maluta, Jaqueline R.; Machado, Sergio A. S.; Chaudhary, Umesh

The modification of traditional electrodes with mesoporous carbons is a promising strategy to produce high performance electrodes for electrochemical sensing. The high surface area of mesoporous carbons provides a large number of electroactive sites for binding analytes. Controlling the pore size and structure of mesoporous carbons and modifying their electronic properties via doping offers additional benefits like maximizing transport and tuning the electrochemical processes associated with analyte detection. This work reports a facile method to produce sulfur-doped ordered mesoporous carbon materials (S-OMC) with uniform pore structure, large pore volume, high surface area and semigraphitic structure. The synthesis used thiophenol asmore » a single source of carbon and sulfur, and iron as a catalyst for low temperature carbonization. The S-OMC material was deposited on a glassy carbon electrode and used as a sensor with high sensitivity (11.7 A L mol-1) and selectivity for chloramphenicol detection in presence of other antibiotics. As a proof-of-concept, the sensor was applied to the direct analysis of the drug in reconstituted powdered milk and in commercial eye drops.« less

Development of a semigraphitic sulfur-doped ordered mesoporous carbon material for electroanalytical applications

DOE PAGES

Maluta, Jaqueline R.; Machado, Sergio A. S.; Chaudhary, Umesh; ...

2017-10-29

The modification of traditional electrodes with mesoporous carbons is a promising strategy to produce high performance electrodes for electrochemical sensing. The high surface area of mesoporous carbons provides a large number of electroactive sites for binding analytes. Controlling the pore size and structure of mesoporous carbons and modifying their electronic properties via doping offers additional benefits like maximizing transport and tuning the electrochemical processes associated with analyte detection. This work reports a facile method to produce sulfur-doped ordered mesoporous carbon materials (S-OMC) with uniform pore structure, large pore volume, high surface area and semigraphitic structure. The synthesis used thiophenol asmore » a single source of carbon and sulfur, and iron as a catalyst for low temperature carbonization. The S-OMC material was deposited on a glassy carbon electrode and used as a sensor with high sensitivity (11.7 A L mol-1) and selectivity for chloramphenicol detection in presence of other antibiotics. As a proof-of-concept, the sensor was applied to the direct analysis of the drug in reconstituted powdered milk and in commercial eye drops.« less

Heat-treated stainless steel felt as scalable anode material for bioelectrochemical systems.

PubMed

Guo, Kun; Soeriyadi, Alexander H; Feng, Huajun; Prévoteau, Antonin; Patil, Sunil A; Gooding, J Justin; Rabaey, Korneel

2015-11-01

This work reports a simple and scalable method to convert stainless steel (SS) felt into an effective anode for bioelectrochemical systems (BESs) by means of heat treatment. X-ray photoelectron spectroscopy and cyclic voltammetry elucidated that the heat treatment generated an iron oxide rich layer on the SS felt surface. The iron oxide layer dramatically enhanced the electroactive biofilm formation on SS felt surface in BESs. Consequently, the sustained current densities achieved on the treated electrodes (1 cm(2)) were around 1.5±0.13 mA/cm(2), which was seven times higher than the untreated electrodes (0.22±0.04 mA/cm(2)). To test the scalability of this material, the heat-treated SS felt was scaled up to 150 cm(2) and similar current density (1.5 mA/cm(2)) was achieved on the larger electrode. The low cost, straightforwardness of the treatment, high conductivity and high bioelectrocatalytic performance make heat-treated SS felt a scalable anodic material for BESs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reduced graphene oxide and vertically aligned carbon nanotubes superhydrophilic films for supercapacitors devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanin, H., E-mail: hudsonzanin@gmail.com; Departamento de Semicondutores, Instrumentos e Fotônica, Faculdade de Engenharia Elétrica e Computação, Universidade Estadual de Campinas, UNICAMP, Campinas 13083-970; Saito, E., E-mail: esaito135@gmail.com

2014-01-01

Graphical abstract: - Highlights: • Graphene nanosheets were produced onto wire rods. • RGO and VACNT-O were evaluated and compared as supercapacitor electrode. • RGO and VACNT-O have structural and electrochemical properties quite similars. • The materials present good specific capacitance, energy storage and power delivery. - Abstract: Reduced graphene oxide (RGO) and vertically aligned carbon nanotubes (VACNT) superhydrophilic films were prepared by chemical vapor deposition techniques for electrical energy storage investigations. These electrodes were characterized in terms of their material and electrochemical properties by scanning electron microscopy (SEM), surface wettability, Fourier transform infrared spectroscopy (FTIR), energy dispersive and Ramanmore » spectroscopies, cyclic voltammetry (CV) and galvanostatic charge–discharge. We observed several physical structural and electrochemical similarities between these carbon-based materials with particular attention to very good specific capacitance, ultra-high energy storage and fast power delivery. Our results showed that the main difference between specific capacitance values is attributed to pseudocapacitive contribution and high density of multiwall nanotubes tips. In this work we have tested a supercapacitor device using the VACNT electrodes.« less

Oxygen-incorporated MoS2 microspheres with tunable interiors as novel electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Sun, Tianhua; Li, Zhangpeng; Liu, Xiaohong; Ma, Limin; Wang, Jinqing; Yang, Shengrong

2017-06-01

In this work, a simple and facile one-step hydrothermal method is developed to synthesize oxygen-incorporated molybdenum disulphide (O-MoS2) microspheres with tunable interiors (solid, yolk-shell and hollow microstructures) by using carbon disulfide (CS2) as soft template and sulfur source simultaneously. The synthesized O-MoS2 microspheres with enlarged interlayer spacing of ca. 9.8 Å show remarkable electrochemical performances as novel electrode materials for supercapacitors (SCs). Specifically, O-MoS2 hollow microsphere exhibits optimal electrochemical performances with a high specific capacitance of 744.2 F g-1 at a current density of 1 A g-1 and a good cycling stability with ca. 77.8% capacitance retention after 10 K continuous charge-discharge cycles at a high current density of 5 A g-1, thus making it a promising electrode material for high-performance SCs. The excellent electrochemical performances are mainly attributed to the enlarged interlayer spacing and the reduced band gap owing to the oxygen incorporation in MoS2 and the hollow microstructure.

Self-template synthesis of double shelled ZnS-NiS1.97 hollow spheres for electrochemical energy storage

NASA Astrophysics Data System (ADS)

Wei, Chengzhen; Ru, Qinglong; Kang, Xiaoting; Hou, Haiyan; Cheng, Cheng; Zhang, Daojun

2018-03-01

In this work, double shelled ZnS-NiS1.97 hollow spheres have been achieved via a simple self-template route, which involves the synthesis of Zn-Ni solid spheres precursors as the self-template and then transformation into double shelled ZnS-NiS1.97 hollow spheres by sulfidation treatment. The as-prepared double shelled ZnS-NiS1.97 hollow spheres possess a high surface area (105.26 m2 g-1) and porous structures. Benefiting from the combined characteristics of novel structures, multi-component, high surface area and porous. When applied as electrode materials for supercapacitors, the double shelled ZnS-NiS1.97hollow spheres deliver a large specific capacitance of 696.8C g-1 at 5.0 A g-1 and a remarkable long lifespan cycling stability (less 5.5% loss after 6000 cycles). Moreover, an asymmetric supercapacitor (ASC) was assembled by utilizing ZnS-NiS1.97 (positive electrode) and activated carbon (negative electrode) as electrode materials. The as-assembled device possesses an energy density of 36 W h kg-1, which can be yet retained 25.6 W h kg-1 even at a power density of 2173.8 W Kg-1, indicating its promising applications in electrochemical energy storage. More importantly, the self-template route is a simple and versatile strategy for the preparation of metal sulfides electrode materials with desired structures, chemical compositions and electrochemical performances.

Metal coordination polymer derived mesoporous Co3O4 nanorods with uniform TiO2 coating as advanced anodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Geng, Hongbo; Ang, Huixiang; Ding, Xianguang; Tan, Huiteng; Guo, Guile; Qu, Genlong; Yang, Yonggang; Zheng, Junwei; Yan, Qingyu; Gu, Hongwei

2016-01-01

In this work, a one-dimensional Co3O4@TiO2 core-shell electrode material with superior electrochemical performance is fabricated by a convenient and controllable route. The approach involves two main steps: the homogeneous deposition of polydopamine and TiO2 layers in sequence on the cobalt coordination polymer and the thermal decomposition of the polymer matrix. The as-prepared electrode material can achieve excellent electrochemical properties and stability as an anode material for lithium ion batteries, such as a high specific capacity of 1279 mA h g-1, good cycling stability (around 803 mA h g-1 at a current density of 200 mA g-1 after 100 cycles), and stable rate performance (around 520 mA h g-1 at a current density of 1000 mA g-1). This dramatic electrochemical performance is mainly attributed to the excellent structural characteristics, which could improve the electrical conductivity and lithium ion mobility, as well as electrolyte permeability and architectural stability during cycling.In this work, a one-dimensional Co3O4@TiO2 core-shell electrode material with superior electrochemical performance is fabricated by a convenient and controllable route. The approach involves two main steps: the homogeneous deposition of polydopamine and TiO2 layers in sequence on the cobalt coordination polymer and the thermal decomposition of the polymer matrix. The as-prepared electrode material can achieve excellent electrochemical properties and stability as an anode material for lithium ion batteries, such as a high specific capacity of 1279 mA h g-1, good cycling stability (around 803 mA h g-1 at a current density of 200 mA g-1 after 100 cycles), and stable rate performance (around 520 mA h g-1 at a current density of 1000 mA g-1). This dramatic electrochemical performance is mainly attributed to the excellent structural characteristics, which could improve the electrical conductivity and lithium ion mobility, as well as electrolyte permeability and architectural stability during cycling. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08570e

Demonstration of Noncorrosive, Capacitance- Based Water-Treatment Technology for Chilled-Water Cooling Systems

DTIC Science & Technology

2014-09-01

monitors were Daniel J. Dunmire [OUSD(AT&L)], Bernie Rodri- guez (IMPW-FM), and Valerie D. Hines (DAIM-ODF). The work was performed by the Materials and...the electrode, a large voltage po- tential is created between the two plates of the capacitor (i.e., the electrode and the grounded steel of the...return (CWR) piping of each condenser. To install the capacitor rods, 1.5 in. mild steel thread-o-lets* were welded into a pipe elbow. Figure 5 shows

Synthesis and characterization of nanostructured electrodes for solid state ionic devices

NASA Astrophysics Data System (ADS)

Zhang, Yuelan

Solid-state electrochemical energy conversion and storage technologies such as fuel cells and lithium ion batteries will influence the way we use energy and the environment we live in. The demands for advanced power sources with high energy efficiency, minimum environmental impact, and low cost have been the impetus for the development of a new generation of batteries and fuel cells. Currently, lithium ion battery technology's greatest disadvantages are long-term cycling stability and high charge/discharge rate capabilities. On the other hand, fuel cell technology's greatest disadvantage is cost. It is found that these problems could be attenuated by the incorporation of nano-structured materials. But, we are still far away from possessing a solid scientific understanding of what goes on at the nanoscale inside these solid state ionic devices, and what is the relationship between nano-structures and their electrochemical properties, especially between the microstructure and electrode polarization and degradation. Electrode polarization represents a voltage loss in an electrochemical energy conversion process. Such understanding is critical for further progress in solid state ionic devices. This thesis focused on the design, fabrication, and characterization of nanostructured porous electrodes with desired composition and microstructure to minimize electrode polarization losses in the application of fuel cells and lithium ion batteries. Various chemical methods such as sol-gel, hydrothermal, surfactant, colloidal and polymer template-assisted processes have been applied in this work. And various characterization techniques have been used to explore the understanding of the microscopic features with electrochemical interfacial properties of the electrodes. Solid-state diffusion often limits the utilization and rate capability of electrode materials in a lithium-ion battery, especially at high charge/discharge rates. When the fluxes of Li+ insertion or extraction exceeds the diffusion-limited rate of Li+ transport within the bulk phase of an electrode, concentration polarization occurs. Further, large volume changes associated with Li+ insertion or extraction could induce stresses in bulk electrodes, potentially leading to mechanical failure. Porous electrodes with high surface-to-volume ratio would increase the electrochemical reaction surface and suppress the mechanical stress. But porous electrodes also increase the tortuosity of mass transport within solid electrodes. Interconnected porous materials would decrease the percolation threshold for porous electrodes. In this work, electrodes with unique architecture for lithium ion batteries have been fabricated to improve the cycleability, rate capability and capacity retention. Spinel LiMn2O4 with interconnected macropores was created using a glycine-nitrate combustion process. Both microstructure and phase crystallinity were optimized by adjusting the fuel/oxidant ratio. This macroporous LiMn2O4 positive electrode exhibited better capacity retention and rate capability than those with larger particle size prepared by solid state reaction. Detailed electrode kinetic studies indicated that the macroporous microstructure promoted lithium diffusion and the overall reaction process was not controlled by lithium diffusion. Nanostructured tin oxide thin films with columnar grains less than 20 nm were deposited on Au/Si substrate using a combustion CVD method. The microstructure was highly porous and open, and thus was easily accessible to liquid electrolyte. In addition, the microstructure with vertical and radial connectivity of active materials led to decreased tortuosity for mass transport within solid electrodes. Nanoparticles accommodated the large volume change during cycling. These thin film electrodes exhibited highly reversible specific capacity and good capacity retention. It is about 93% after 80 cycles at a charge/discharge rate of 0.3 mA/cm2. When discharged at 0.9 mA/cm2, the obtained capacity retention was about 64% of the capacity at 0.3 mA/cm2. Cathodic interfacial polarization represents the predominant loss in a low-temperature SOFC. In this thesis, several porous nanocomposite electrodes of mixed ionic and electronic conductors (MIEC) with high surface areas were designed and fabricated to improve to minimize the polarization resistance. For the first time, regular, homogeneous and dual porous MIEC electrodes were successfully fabricated using breath figure templating, which is self-assembly of the water droplets in polymer solution. The homogeneous macropores promoted rapid mass transport by decreasing the tortuosity. Further, mesoporous microstructure provided more surface areas for gas adsorption and more TPBs for the electrochemical reactions. The interfacial polarization resistances were 0.94 and 0.39 Ocm 2 at 700 and 750°C, respectively. Furthermore, electrodes consisting of strontium doped lanthanum manganite (LSM) and gadolinium doped ceria (GDC) were developed with a modified sol-gel process for honeycomb SOFCs based on stabilized zirconia electrolytes. The sol gel derived cathodes with fine grain size and large specific surface area, showed much lower interfacial polarization resistances than those prepared by other processing methods. And this process developed strong bonding between the electrode and electrolyte even at low temperatures. The interfacial polarization resistances were 0.65 and 0.16 Ocm 2 at 650 and 750°C, respectively. The mesoscopic regime of overlapping space charge effects had a positive effect on the electrode kinetics. Ceria is a very important catalytic material for fuel reforming in SOFCs and CO poisoning in PEM fuel cells. Especially, the design of a new generation SOFC requires the in-situ reforming of hydrocarbon fuels. In this work, nanostructured ceria was developed via a controlled hydrothermal process in a mixed water-ethanol medium. The microstructure, formation mechanism, and their surface catalytic properties were investigated.

Recent Progress in Iron-Based Electrode Materials for Grid-Scale Sodium-Ion Batteries.

PubMed

Fang, Yongjin; Chen, Zhongxue; Xiao, Lifen; Ai, Xinping; Cao, Yuliang; Yang, Hanxi

2018-03-01

Grid-scale energy storage batteries with electrode materials made from low-cost, earth-abundant elements are needed to meet the requirements of sustainable energy systems. Sodium-ion batteries (SIBs) with iron-based electrodes offer an attractive combination of low cost, plentiful structural diversity and high stability, making them ideal candidates for grid-scale energy storage systems. Although various iron-based cathode and anode materials have been synthesized and evaluated for sodium storage, further improvements are still required in terms of energy/power density and long cyclic stability for commercialization. In this Review, progress in iron-based electrode materials for SIBs, including oxides, polyanions, ferrocyanides, and sulfides, is briefly summarized. In addition, the reaction mechanisms, electrochemical performance enhancements, structure-composition-performance relationships, merits and drawbacks of iron-based electrode materials for SIBs are discussed. Such iron-based electrode materials will be competitive and attractive electrodes for next-generation energy storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Graphene-passivated cobalt as a spin-polarized electrode: growth and application to organic spintronics

NASA Astrophysics Data System (ADS)

Zhou, Guoqing; Tang, Guoqiang; Li, Tian; Pan, Guoxing; Deng, Zanhong; Zhang, Fapei

2017-03-01

The ferromagnetic electrode on which a clean high-quality electrode/interlayer interface is formed, is critical to achieve efficient injection of spin-dependent electrons in spintronic devices. In this work, we report on the preparation of graphene-passivated cobalt electrodes for application in vertical spin valves (SVs). In this strategy, high-quality monolayer and bi-layer graphene sheets have been grown directly on the crystal Co film substrates in a controllable process by chemical vapor deposition. The electrode is oxidation resistant and ensures a clean crystalline graphene/Co interface. The AlO x -based magnetic junction devices using such bottom electrodes, exhibit a negative tunnel magneto-resistance (TMR) of ca. 1.0% in the range of 5 K-300 K. Furthermore, we have also fabricated organic-based SVs employing a thin layer of fullerene C60 or an N-type polymeric semiconductor as the interlayer. The devices of both materials show a tunneling behavior of spin-polarized electron transport as well as appreciable TMR effect, demonstrating the high potential of such graphene-coated Co electrodes for organic-based spintronics.

Performance of lightweight nickel electrodes

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1988-01-01

The NASA Lewis Research Center is currently developing nickel electrodes for nickel-hydrogen (Ni-H2) batteries. These electrodes are lighter in weight and have higher energy densities than the heavier state-of-the-art (SOA) sintered nickel electrodes. In the present approach, lightweight materials or plaques are used as conductive supports for the nickel hydroxide active material. These plaques (fiber and felt, nickel plated plastic and graphite) are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. Evaluation is performed in half cells structured in the bipolar configuration. Initial performance tests include capacity measurements at five discharge levels, C/2, 1.0C 1.37C, 2.0C and 2.74C. The electrodes that pass the initial tests are life cycle tested in a low Earth orbit regime at 80 percent depth of discharge. Different formulations of nickel fiber materials obtained from several manufacturers are currently being tested as possible candidates for nickel electrodes. One particular lightweight fiber mat electrode has accumulated over 3000 cycles to date, with stable capacity and voltage. Life and performance data of this electrode were investigated and presented. Good dimensional stability and active material adherence have been demonstrated in electrodes made from this lightweight plaque.

Electrochemical slurry compositions and methods for preparing the same

DOEpatents

Doherty, Tristan; Limthongkul, Pimpa; Butros, Asli; Duduta, Mihai; Cross, III, James C.

2016-11-01

Embodiments described herein generally relate to semi-solid suspensions, and more particularly to systems and methods for preparing semi-solid suspensions for use as electrodes in electrochemical devices such as, for example batteries. In some embodiments, a method for preparing a semi-solid electrode includes combining a quantity of an active material with a quantity of an electrolyte to form an intermediate material. The intermediate material is then combined with a conductive additive to form an electrode material. The electrode material is mixed to form a suspension having a mixing index of at least about 0.80 and is then formed into a semi-solid electrode.

Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

DOEpatents

Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

2015-10-27

Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqeuous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

Three-Dimensional Honeycomb-Structural LiAlO2-Modified LiMnPO4 Composite with Superior High Rate Capability as Li-Ion Battery Cathodes.

PubMed

Li, Junzhe; Luo, Shaohua; Ding, Xueyong; Wang, Qing; He, Ping

2018-04-04

In the efforts toward the rapidly increasing demands for high-power application, cathode materials with three-dimensional (3D) architectures have been proposed. Here, we report the construction of the 3D LiAlO 2 -LiMnPO 4 /C cathode materials for lithium-ion batteries in an innovation way. The as-prepared 3D active materials LiMnPO 4 /C and the honeycomb-like Li-ion conductor LiAlO 2 framework are used as working electrode directly without additional usage of polymeric binder. The electrochemical performance has been improved significantly due to the special designed core-shell architectures of LiMnPO 4 /C@LiAlO 2 . The 3D binder-free electrode exhibits high rate capability as well as superior cycling stability with a capability of ∼105 mAh g -1 and 98.4% capacity retention after 100 cycles at a high discharge rate of 10 C. Such synthesis method adopted in our work can be further extended to other promising candidates and would also inspire new avenues of development of 3D materials for lithium-ion batteries.

Hybrid supercapacitor-battery materials for fast electrochemical charge storage

PubMed Central

Vlad, A.; Singh, N.; Rolland, J.; Melinte, S.; Ajayan, P. M.; Gohy, J.-F.

2014-01-01

High energy and high power electrochemical energy storage devices rely on different fundamental working principles - bulk vs. surface ion diffusion and electron conduction. Meeting both characteristics within a single or a pair of materials has been under intense investigations yet, severely hindered by intrinsic materials limitations. Here, we provide a solution to this issue and present an approach to design high energy and high power battery electrodes by hybridizing a nitroxide-polymer redox supercapacitor (PTMA) with a Li-ion battery material (LiFePO4). The PTMA constituent dominates the hybrid battery charge process and postpones the LiFePO4 voltage rise by virtue of its ultra-fast electrochemical response and higher working potential. We detail on a unique sequential charging mechanism in the hybrid electrode: PTMA undergoes oxidation to form high-potential redox species, which subsequently relax and charge the LiFePO4 by an internal charge transfer process. A rate capability equivalent to full battery recharge in less than 5 minutes is demonstrated. As a result of hybrid's components synergy, enhanced power and energy density as well as superior cycling stability are obtained, otherwise difficult to achieve from separate constituents. PMID:24603843

The anodic emitter effect and its inversion demonstrated by temperature measurements at doped and undoped tungsten electrodes

NASA Astrophysics Data System (ADS)

Hoebing, T.; Bergner, A.; Hermanns, P.; Mentel, J.; Awakowicz, P.

2016-04-01

The admixture of a small amount of emitter oxides, e.g. \\text{Th}{{\\text{O}}2} , \\text{L}{{\\text{a}}2}{{\\text{O}}3} or \\text{C}{{\\text{e}}2}{{\\text{O}}3} to tungsten generates the so-called emitter effect. It reduces the work function of tungsten cathodes, that are applied in high intensity discharge (HID) lamps. After leaving the electrode bulk and moving to the surface, a monolayer of Th, La, or Ce atoms is formed on the surface, which reduces the effective work function ϕ. Depending on the coverage of the electrode, the effective reduction in ϕ is subjected to the thermal desorption of the monolayer from the hot electrode surface. The thermal desorption of emitter atoms from the cathode is compensated not only by the supply from the interior of the electrode and by surface diffusion of the emitter material to its tip, but also to a large extent by a repatriation of the emitter ions from the plasma by the strong electric field in front of the cathode. Yet, an emitter ion current from the arc discharge to the anode may only be present, if the anode is cold enough to refrain from thermionic emission. Therefore, the ability of emitter oxides to reduce the temperature of tungsten anodes is only given for a moderate temperature so that the thermal desorption is low and an additional ion current is present in front of the anode. A higher electrode temperature leads to their evaporation and to an inversion of the emitter effect, which increases the temperature of the respective anodes in comparison with pure tungsten anodes. Within this article, the emitter effect of doped tungsten anodes and the transition to its inversion is investigated for thoriated, lanthanated, and ceriated tungsten electrodes by measurements of the electrode temperature in dependence on the discharge current. It is shown for a lanthanated and a ceriated anode that the emitter effect is sustained by an ion current at anode temperatures at which the thermal evaporation of emitter material is completed.

Method of making electrodes for electrochemical cell

DOEpatents

Kaun, Thomas D.; Kilsdonk, Dennis J.

1983-01-01

A method of making an electrode for an electrochemical cell in which particulate electrode-active material is mixed with a liquid organic carrier chemically inert with respect to the electrode-active material, mixing the liquid carrier to form an extrudable slurry. The liquid carrier is present in an amount of from about 10 to about 50 percent by volume of the slurry, and then the carrier is removed from the slurry leaving the electrode-active material.

High-Performance Asymmetric Supercapacitors of MnCo2O4 Nanofibers and N-Doped Reduced Graphene Oxide Aerogel.

PubMed

Pettong, Tanut; Iamprasertkun, Pawin; Krittayavathananon, Atiweena; Sukha, Phansiri; Sirisinudomkit, Pichamon; Seubsai, Anusorn; Chareonpanich, Metta; Kongkachuichay, Paisan; Limtrakul, Jumras; Sawangphruk, Montree

2016-12-14

The working potential of symmetric supercapacitors is not so wide because one type of material used for the supercapacitor electrodes prefers either positive or negative charge to both charges. To address this problem, a novel asymmetrical supercapacitor (ASC) of battery-type MnCo 2 O 4 nanofibers (NFs)//N-doped reduced graphene oxide aerogel (N-rGO AE ) was fabricated in this work. The MnCo 2 O 4 NFs at the positive electrode store the negative charges, i.e., solvated OH - , while the N-rGO AE at the negative electrode stores the positive charges, i.e., solvated K + . An as-fabricated aqueous-based MnCo 2 O 4 //N-rGO AE ASC device can provide a wide operating potential of 1.8 V and high energy density and power density at 54 W h kg -1 and 9851 W kg -1 , respectively, with 85.2% capacity retention over 3000 cycles. To understand the charge storage reaction mechanism of the MnCo 2 O 4 , the synchrotron-based X-ray absorption spectroscopy (XAS) technique was also used to determine the oxidation states of Co and Mn at the MnCo 2 O 4 electrode after being electrochemically tested. The oxidation number of Co is oxidized from +2.76 to +2.85 after charging and reduced back to +2.75 after discharging. On the other hand, the oxidation state of Mn is reduced from +3.62 to +3.44 after charging and oxidized to +3.58 after discharging. Understanding in the oxidation states of Co and Mn at the MnCo 2 O 4 electrode here leads to the awareness of the uncertain charge storage mechanism of the spinel-type oxide materials. High-performance ASC here in this work may be practically used in high-power applications.

Influence of electrolyte ion-solvent interactions on the performances of supercapacitors porous carbon electrodes

NASA Astrophysics Data System (ADS)

Decaux, C.; Matei Ghimbeu, C.; Dahbi, M.; Anouti, M.; Lemordant, D.; Béguin, F.; Vix-Guterl, C.; Raymundo-Piñero, E.

2014-10-01

The development of advanced and safe electrochemical supercapacitors or hybrid supercapacitors combining a battery electrode material such as graphite and a porous carbon electrode implies the use of new electrolytes containing a tetra-alkylammonium or lithium salt dissolved preferentially in a safe and environmentally friendly solvent such as alkylcarbonates. In those systems, the carbon porosity of the activated carbon electrode controls the electrochemical behavior of the whole device. In this work, it is demonstrated that electrolytes containing highly polarizing ions such as Li+ dissolved in polar solvents such as alkylcarbonates do not completely loss their solvation shell at the opposite of what is observed for poorly solvated cations like TEABF4. As a consequence, the optimal carbon pore size for obtaining the largest energy density, while keeping a high power density, is wider when strongly solvated cations, like Li+ are used than for conventional organic electrolytes using acetonitrile as solvent and TEA+ as salt cations. TEA+ cations are easily desolvated and hence are able to penetrate in small pores matching the dimensions of bare ions. The dissimilarity of behavior of alkylcarbonates and acetonitrile based electrolytes highlights the importance of ion-solvent interactions when searching the optimal porous texture for the electrode material.

A novel route for electrosynthesis of CuCr(2)O(4) nanocomposite with p-type conductive polymer as a high performance material for electrochemical supercapacitors.

PubMed

Shayeh, Javad Shabani; Sadeghinia, Mohammad; Siadat, Seyed Omid Ranaei; Ehsani, Ali; Rezaei, Mehran; Omidi, Meisam

2017-06-15

In this work, supercapacitive performance of polypyrrole copper chromate nano particles (Ppy/CuCr 2 O 4 NPs) was studied. CuCr 2 O 4 NPs with the average size of 20nm were synthesized simply by hydrothermal method and the composite electrodes were then electropolymerized on the surface of glassy carbon electrode. Common surface analysis techniques such as scanning electron microscopy (SEM), transmission electron microscopy(TEM) and Fourier transform infrared (FTIR) were used to study the morphology and structure of the composite. Furthermore, for electrochemical evaluation of composite electrodes, techniques including cyclic voltammetry (CV), galvanostatic charge discharge (CD) and impedance spectroscopy (EIS) were used. Using cyclic voltammetry, the specific capacitance values of Ppy and Ppy/CuCr 2 O 4 NPs were calculated to be 109 and 508 F g -1 , respectively. Results show that using CuCr 2 O 4 NPs in the structure of polymeric films led to increased specific capacitance of composite electrodes more than four times that of poly pyrrole. Increasing the conductivity and stability of composite electrodes through continuous cycles are the other advantages of using CuCr 2 O 4 NPs as active materials in a polymeric structure. Copyright © 2017 Elsevier Inc. All rights reserved.

Honeycomb-Like Interconnected Network of Nickel Phosphide Heteronanoparticles with Superior Electrochemical Performance for Supercapacitors.

PubMed

Liu, Shude; Sankar, Kalimuthu Vijaya; Kundu, Aniruddha; Ma, Ming; Kwon, Jang-Yeon; Jun, Seong Chan

2017-07-05

Transition-metal-based heteronanoparticles are attracting extensive attention in electrode material design for supercapacitors owing to their large surface-to-volume ratios and inherent synergies of individual components; however, they still suffer from limited interior capacity and cycling stability due to simple geometric configurations, low electrochemical activity of the surface, and poor structural integrity. Developing an elaborate architecture that endows a larger surface area, high conductivity, and mechanically robust structure is a pressing need to tackle the existing challenges of electrode materials. This work presents a supercapacitor electrode consisting of honeycomb-like biphasic Ni 5 P 4 -Ni 2 P (Ni x P y ) nanosheets, which are interleaved by large quantities of nanoparticles. The optimized Ni x P y delivers an ultrahigh specific capacity of 1272 C g -1 at a current density of 2 A g -1 , high rate capability, and stability. An asymmetric supercapacitor employing as-synthesized Ni x P y as the positive electrode and activated carbon as the negative electrode exhibits significantly high power and energy densities (67.2 W h kg -1 at 0.75 kW kg -1 ; 20.4 W h kg -1 at 15 kW kg -1 ). These results demonstrate that the novel nanostructured Ni x P y can be potentially applied in high-performance supercapacitors.

Effective dose in the manufacturing process of rutile covered welding electrodes.

PubMed

Herranz, M; Rozas, S; Pérez, C; Idoeta, R; Núñez-Lagos, R; Legarda, F

2013-03-01

Shielded metal arc welding using covered electrodes is the most common welding process. Sometimes the covering contains naturally occurring radioactive materials (NORMs). In Spain the most used electrodes are those covered with rutile mixed with other materials. Rutile contains some detectable natural radionuclides, so it can be considered a NORM. This paper mainly focuses on the use of MCNP (Monte Carlo N-Particle Transport Code) as a predictive tool to obtain doses in a factory which produces this type of electrode and assess the radiological impact in a specific facility after estimating the internal dose.To do this, in the facility, areas of highest radiation and positions of workers were identified, radioactive content of rutile and rutile covered electrodes was measured, and, considering a worst possible scenario, external dose at working points has been calculated using MCNP. This procedure has been validated comparing the results obtained with those from a pressurised ionisation chamber and TLD dosimeters. The internal dose has been calculated using DCAL (dose and risk calculation). The doses range between 8.8 and 394 μSv yr(-1), always lower than the effective dose limit for the public, 1 mSv yr(-1). The highest dose corresponds to the mixing area.

Comparative study of graphene and its derivative materials as an electrode in OLEDs

NASA Astrophysics Data System (ADS)

Srivastava, Anshika; Kumar, Brijesh

2018-04-01

In current scenario, the organic materials have given a revolutionary evolution in the electronics industry. As, the organic light emitting diodes (OLEDs) have almost replaced the conventional technologies due to the use of organic based materials. However, the next generations OLEDs are intensively desired nowadays for high definition display technology. There are various concern involved in the successful design of OLEDs. Electrodes are one of the electrical conductors, which play a vital role in the construction of OLEDs. The performance of OLED is majorly affected by the material used for electrodes. Due to the requirement of transparent, flexible and inexpensive anodes in bottom emissive OLEDs, ITO was replaced by graphene material. Graphene is a single layer 2-dimensional transparent carbon allotrope which showed prodigious potential to escalate the device performance. Although graphene demonstrated impressive characteristics in various applications, it showed unfavorable work function for many other devices. Thus, derivative materials of graphene such as graphene oxide, graphane and β - graphdiyne were synthesized by several researchers. By comparing graphene and its derivatives as an anode of OLEDs, it has been found that graphene oxide showed the preeminent performance among all. In this paper, all the comparisons are investigated by using a standard device constructed by piling layers of anode/ m_MTDATA/ NPB/ Alq3: QAD/ Alq3/ cathode in TCAD ATLAS device simulator.

Ionic Liquid Directed Mesoporous Carbon Nanoflakes as an Effiencient Electrode material

NASA Astrophysics Data System (ADS)

Kong, Lirong; Chen, Wei

2015-12-01

Supercapacitors are considered to be the most promising approach to meet the pressing requirements for energy storage devices. The electrode materials for supercapacitors have close relationship with their electrochemical properties and thus become the key point to improve their energy storage efficiency. Herein, by using poly (vinylidene fluoride-co-hexafluoropropylene) and ionic liquid as the dual templates, polyacrylonitrile as the carbon precursor, a flake-like carbon material was prepared by a direct carbonization method. In this method, poly (vinylidene fluoride-co-hexafluoropropylene) worked as the separator for the formation of isolated carbon flakes while aggregated ionic liquid worked as the pore template. The obtained carbon flakes exhibited a specific capacitance of 170 F/g at 0.1 A/g, a high energy density of 12.2 Wh/kg and a high power density of 5 kW/kg at the current of 10 A/g. It also maintained a high capacitance retention capability with almost no declination after 500 charge-discharge cycles. The ionic liquid directed method developed here also provided a new idea for the preparation of hierarchically porous carbon nanomaterials.

Dielectric elastomers with novel highly-conducting electrodes

NASA Astrophysics Data System (ADS)

Böse, Holger; Uhl, Detlev

2013-04-01

Beside the characteristics of the elastomer material itself, the performance of dielectric elastomers in actuator, sensor as well as generator applications depends also on the properties of the electrode material. Various electrode materials based on metallic particles dispersed in a silicone matrix were manufactured and investigated. Anisotropic particles such as silver-coated copper flakes and silver-coated glass flakes were used for the preparation of the electrodes. The concentration of the metallic particles and the thickness of the electrode layers were varied. Specific conductivities derived from resistance measurements reached about 100 S/cm and surmount those of the reference materials based on graphite and carbon black by up to three orders of magnitude. The high conductivities of the new electrode materials can be maintained even at very large stretch deformations up to 200 %.

The Weinstein conjecture with multiplicities on spherizations

NASA Astrophysics Data System (ADS)

Hertzberg, Benjamin J.

2011-07-01

Si-based anodes have recently received considerable attention for use in Li-ion batteries, due to their extremely high specific capacity---an order of magnitude beyond that offered by conventional graphite anode materials. However, during the lithiation process, Si-based anodes undergo extreme increases in volume, potentially by more than 300 %. The stresses produced within the electrode by these volume changes can damage the electrode binder, the active Si particles and the solid electrolyte interphase (SEI), causing the electrode to rapidly fail and lose capacity. These problems can be overcome by producing new anode materials incorporating both Si and C, which may offer a favorable combination of the best properties of both materials, and which can be designed with internal porosity, thereby buffering the high strains produced during battery charge and discharge with minimal overall volume changes. However, in order to develop useful anode materials, we must gain a thorough understanding of the structural, microstructural and chemical changes occurring within the electrode during the lithiation and delithiation process, and we must develop new processes for synthesizing composite anode particles which can survive the extreme strains produced during lithium intercalation of Si and exhibit no volume changes in spite of the volume changes in Si. In this work we have developed several novel synthesis processes for producing internally porous Si-C nanocomposite anode materials for Li-ion batteries. These nanocomposites possess excellent specific capacity, Coulombic efficiency, cycle lifetime, and rate capability. We have also investigated the influence of a range of different parameters on the electrochemical performance of these materials, including pore size and shape, carbon and silicon film thickness and microstructure, and binder chemistry.

3D Interconnected and Multiwalled Carbon@MoS2 @Carbon Hollow Nanocables as Outstanding Anodes for Na-Ion Batteries.

PubMed

Wang, Yan; Qu, Qunting; Li, Guangchao; Gao, Tian; Qian, Feng; Shao, Jie; Liu, Weijie; Shi, Qiang; Zheng, Honghe

2016-11-01

Currently, the specific capacity and cycling performance of various MoS 2 /carbon-based anode materials for Na-ion storage are far from satisfactory due to the insufficient structural stability of the electrode, incomplete protection of MoS 2 by carbon, difficult access of electrolyte to the electrode interior, as well as inactivity of the adopted carbon matrix. To address these issues, this work presents the rational design and synthesis of 3D interconnected and hollow nanocables composed of multiwalled carbon@MoS 2 @carbon. In this architecture, (i) the 3D nanoweb-like structure brings about excellent mechanical property of the electrode, (ii) the ultrathin MoS 2 nanosheets are sandwiched between and doubly protected by two layers of porous carbon, (iii) the hollow structure of the primary nanofibers facilitates the access of electrolyte to the electrode interior, (iv) the porous and nitrogen-doping properties of the two carbon materials lead to synergistic Na-storage of carbon and MoS 2 . As a result, this hybrid material as the anode material of Na-ion battery exhibits fast charge-transfer reaction, high utilization efficiency, and ultrastability. Outstanding reversible capacity (1045 mAh g -1 ), excellent rate behavior (817 mAh g -1 at 7000 mA g -1 ), and good cycling performance (747 mAh g -1 after 200 cycles at 700 mA g -1 ) are obtained. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Materiais a base de oxidos com estrutura do tipo perovskite e compositos como anodos de PCES: Propriedades Funcionais e Comportamento Eletroquimico em Celulas com Eletrolitos Solidos a Base de Galatos e Silicatos

NASA Astrophysics Data System (ADS)

Kolotygin, Vladislav

This work was focused on the analysis of transport, thermomechanical and electrochemical properties of a series of perovskite-like oxide materials and composites for potential applications as anodes of intermediate-temperature solid oxide fuel cells (SOFCs) with lanthanum gallate and silicate solid electrolytes. The primary attention was centered on A(Mn,Nb)O3-delta (A = Sr, Ca) and (La,Sr)(Mn,Ti)O3-based systems, lanthanum chromite substituted with acceptor-type and variable-valence cations, and various Ni-containing cermets. Emphasis was given to phase stability of the materials, their crystal structure, microstructure of porous electrode layers and dense ceramics, electronic conductivity, Seebeck coefficient, oxygen permeability, thermal and chemical induced expansion, and anodic overpotentials of the electrodes deposited onto (La,Sr)(Ga,Mg)O3- and La10(Si,Al)6O27-based electrolyte membranes. In selected cases, roles of oxygen diffusivity, states of the transition metal cations relevant for the electronic transport, catalytically active additives and doped ceria protective interlayers introduced in the model electrochemical cells were assessed. The correlations between transport properties of the electrode materials and electrochemical behavior of porous electrodes showed that the principal factors governing anode performance include, in particular, electronic conduction of the anode compositions and cation interdiffusion between the electrodes and solid electrolytes. The latter is critically important for the silicatebased electrolyte membranes, leading to substantially worse anode properties compared to the electrochemical cells with lanthanum gallate solid electrolyte. The results made it possible to select several anode compositions exhibiting lower area-specific electrode resistivity compared to known analogues, such as (La,Sr)(Cr,Mn)O3-delta.

In situ preparation of NiS2/CoS2 composite electrocatalytic materials on conductive glass substrates with electronic modulation for high-performance counter electrodes of dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Li, Faxin; Wang, Jiali; Zheng, Li; Zhao, Yaqiang; Huang, Niu; Sun, Panpan; Fang, Liang; Wang, Lei; Sun, Xiaohua

2018-04-01

The electrocatalytic composite materials of honeycomb structure NiS2 nanosheets loaded with metallic CoS2 nanoparticles are in situ prepared on F doped SnO2 conductive glass (FTO) substrates used as counter electrodes of DSSCs through chemical bath deposition (CBD) and sulfidizing process. Single crystalline NiS2 honeycomb structure array lay a foundation for the large surface area of NiS2/CoS2 composite CEs. The formed NiS2/CoS2 nanointerface modulates electronic structure of composite CEs from the synergetic interactions between CoS2 nanoparticles and NiS2 nanosheets, which dramatically improves the electrocatalytic activity of NiS2/CoS2 composite CEs; Metallic CoS2 nanoparticles covering NiS2 nanosheets electrodes adjusts the electrodes' structure and then reduces the series resistance (Rs) and the Nernst diffusion resistance (Zw) of counter electrodes. The improvement of these areas greatly enhances the electrocatalytic performance of CEs and the short circuit current density (Jsc) and Fill factor (FF) of DSSCs. Impressively, the DSSC based on NiS2/CoS2-0.1 CE shows the best photovoltaic performance with photovoltaic conversion efficiency of 8.22%, which is 24.36% higher than that (6.61%) of the DSSC with Pt CE. And the NiS2/CoS2-0.1 CE also displays a good stability in the iodine based electrolyte. This work indicates that rational construction of composite electrocatalytic materials paves an avenue for high-performance counter electrodes of DSSCs.

Electrodes for microfluidic applications

DOEpatents

Crocker, Robert W [Fremont, CA; Harnett, Cindy K [Livermore, CA; Rognlien, Judith L [Livermore, CA

2006-08-22

An electrode device for high pressure applications. These electrodes, designed to withstand pressure of greater than 10,000 psi, are adapted for use in microfluidic devices that employ electrokinetic or electrophoretic flow. The electrode is composed, generally, of an outer electrically insulating tubular body having a porous ceramic frit material disposed in one end of the outer body. The pores of the porous ceramic material are filled with an ion conductive polymer resin. A conductive material situated on the upper surface of the porous ceramic frit material and, thus isolated from direct contact with the electrolyte, forms a gas diffusion electrode. A metal current collector, in contact with the gas diffusion electrode, provides connection to a voltage source.

HSPES membrane electrode assembly

NASA Technical Reports Server (NTRS)

Kindler, Andrew (Inventor); Yen, Shiao-Ping (Inventor)

2000-01-01

An improved fuel cell electrode, as well as fuel cells and membrane electrode assemblies that include such an electrode, in which the electrode includes a backing layer having a sintered layer thereon, and a non-sintered free-catalyst layer. The invention also features a method of forming the electrode by sintering a backing material with a catalyst material and then applying a free-catalyst layer.

High-Capacity Cathode Material with High Voltage for Li-Ion Batteries

DOE PAGES

Shi, Ji -Lei; Xiao, Dong -Dong; Ge, Mingyuan; ...

2018-01-15

Electrochemical energy storage devices with a high energy density are an important technology in modern society, especially for electric vehicles. The most effective approach to improve the energy density of batteries is to search for high-capacity electrode materials. According to the concept of energy quality, a high-voltage battery delivers a highly useful energy, thus providing a new insight to improve energy density. Based on this concept, a novel and successful strategy to increase the energy density and energy quality by increasing the discharge voltage of cathode materials and preserving high capacity is proposed. The proposal is realized in high-capacity Li-richmore » cathode materials. The average discharge voltage is increased from 3.5 to 3.8 V by increasing the nickel content and applying a simple after-treatment, and the specific energy is improved from 912 to 1033 Wh kg-1. The current work provides an insightful universal principle for developing, designing, and screening electrode materials for high energy density and energy quality.« less

Recent Progress on Flexible and Wearable Supercapacitors.

PubMed

Xue, Qi; Sun, Jinfeng; Huang, Yan; Zhu, Minshen; Pei, Zengxia; Li, Hongfei; Wang, Yukun; Li, Na; Zhang, Haiyan; Zhi, Chunyi

2017-12-01

Recently, wearable electronic devices including electrical sensors, flexible displays, and health monitors have received considerable attention and experienced rapid progress. Wearable supercapacitors attract tremendous attention mainly due to their high stability, low cost, fast charging/discharging, and high efficiency; properties that render them value for developing fully flexible devices. In this Concept, the recent achievements and advances made in flexible and wearable supercapacitors are presented, especially highlighting the promising performances of yarn/fiber-shaped and planar supercapacitors. On the basis of their working mechanism, electrode materials including carbon-based materials, metal oxide-based materials, and conductive polymers with an emphasis on the performance-optimization method are introduced. The latest representative techniques and active materials of recently developed supercapacitors with superior performance are summarized. Furthermore, the designs of 1D and 2D electrodes are discussed according to their electrically conductive supporting materials. Finally, conclusions, challenges, and perspective in optimizing and developing the electrochemical performance and function of wearable supercapacitors for their practical utility are addressed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-Capacity Cathode Material with High Voltage for Li-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Ji -Lei; Xiao, Dong -Dong; Ge, Mingyuan

Electrochemical energy storage devices with a high energy density are an important technology in modern society, especially for electric vehicles. The most effective approach to improve the energy density of batteries is to search for high-capacity electrode materials. According to the concept of energy quality, a high-voltage battery delivers a highly useful energy, thus providing a new insight to improve energy density. Based on this concept, a novel and successful strategy to increase the energy density and energy quality by increasing the discharge voltage of cathode materials and preserving high capacity is proposed. The proposal is realized in high-capacity Li-richmore » cathode materials. The average discharge voltage is increased from 3.5 to 3.8 V by increasing the nickel content and applying a simple after-treatment, and the specific energy is improved from 912 to 1033 Wh kg-1. The current work provides an insightful universal principle for developing, designing, and screening electrode materials for high energy density and energy quality.« less

All-graphene-battery: bridging the gap between supercapacitors and lithium ion batteries

NASA Astrophysics Data System (ADS)

Kim, Haegyeom; Park, Kyu-Young; Hong, Jihyun; Kang, Kisuk

2014-06-01

Herein, we propose an advanced energy-storage system: all-graphene-battery. It operates based on fast surface-reactions in both electrodes, thus delivering a remarkably high power density of 6,450 W kg-1total electrode while also retaining a high energy density of 225 Wh kg-1total electrode, which is comparable to that of conventional lithium ion battery. The performance and operating mechanism of all-graphene-battery resemble those of both supercapacitors and batteries, thereby blurring the conventional distinction between supercapacitors and batteries. This work demonstrates that the energy storage system made with carbonaceous materials in both the anode and cathode are promising alternative energy-storage devices.

All-graphene-battery: bridging the gap between supercapacitors and lithium ion batteries.

PubMed

Kim, Haegyeom; Park, Kyu-Young; Hong, Jihyun; Kang, Kisuk

2014-06-13

Herein, we propose an advanced energy-storage system: all-graphene-battery. It operates based on fast surface-reactions in both electrodes, thus delivering a remarkably high power density of 6,450 W kg(-1)(total electrode) while also retaining a high energy density of 225 Wh kg(-1)(total electrode), which is comparable to that of conventional lithium ion battery. The performance and operating mechanism of all-graphene-battery resemble those of both supercapacitors and batteries, thereby blurring the conventional distinction between supercapacitors and batteries. This work demonstrates that the energy storage system made with carbonaceous materials in both the anode and cathode are promising alternative energy-storage devices.

All-graphene-battery: bridging the gap between supercapacitors and lithium ion batteries

PubMed Central

Kim, Haegyeom; Park, Kyu-Young; Hong, Jihyun; Kang, Kisuk

2014-01-01

Herein, we propose an advanced energy-storage system: all-graphene-battery. It operates based on fast surface-reactions in both electrodes, thus delivering a remarkably high power density of 6,450 W kg−1total electrode while also retaining a high energy density of 225 Wh kg−1total electrode, which is comparable to that of conventional lithium ion battery. The performance and operating mechanism of all-graphene-battery resemble those of both supercapacitors and batteries, thereby blurring the conventional distinction between supercapacitors and batteries. This work demonstrates that the energy storage system made with carbonaceous materials in both the anode and cathode are promising alternative energy-storage devices. PMID:24923290

Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center and Reaction Center Plus Light Harvesting Complexes

NASA Astrophysics Data System (ADS)

Yaghoubi, Houman

Harvesting solar energy can potentially be a promising solution to the energy crisis now and in the future. However, material and processing costs continue to be the most important limitations for the commercial devices. A key solution to these problems might lie within the development of bio-hybrid solar cells that seeks to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. The bio-photoelectrochemical cell technologies exploit biomimetic means of energy conversion by utilizing plant-derived photosystems which can be inexpensive and ultimately the most sustainable alternative. Plants and photosynthetic bacteria harvest light, through special proteins called reaction centers (RCs), with high efficiency and convert it into electrochemical energy. In theory, photosynthetic RCs can be used in a device to harvest solar energy and generate 1.1 V open circuit voltage and ~1 mA cm-2 short circuit photocurrent. Considering the nearly perfect quantum yield of photo-induced charge separation, efficiency of a protein-based solar cell might exceed 20%. In practice, the efficiency of fabricated devices has been limited mainly due to the challenges in the electron transfer between the protein complex and the device electrodes as well as limited light absorption. The overarching goal of this work is to increase the power conversion efficiency in protein-based solar cells by addressing those issues (i.e. electron transfer and light absorption). This work presents several approaches to increase the charge transfer rate between the photosynthetic RC and underlying electrode as well as increasing the light absorption to eventually enhance the external quantum efficiency (EQE) of bio-hybrid solar cells. The first approach is to decrease the electron transfer distance between one of the redox active sites in the RC and the underlying electrode by direct attachment of the of protein complex onto Au electrodes via surface exposed cysteine residues. This resulted in photocurrent densities as large as ~600 nA cm-2 while still the incident photon to generated electron quantum efficiency was as low as %3 x 10-4. 2- The second approach is to immobilize wild type RCs of Rhodobacter sphaeroides on the surface of a Au underlying electrode using self-assembled monolayers of carboxylic acid terminated oligomers and cytochrome c charge mediating layers, with a preferential orientation from the primary electron donor site. This approach resulted in EQE of up to 0.06%, which showed 200 times efficiency improvement comparing to the first approach. In the third approach, instead of isolated protein complexes, RCs plus light harvesting (LH) complexes were employed for a better photon absorption. Direct attachment of RC-LH1 complexes on Au working electrodes, resulted in 0.21% EQE which showed 3.5 times efficiency improvement over the second approach (700 times higher than the first approach). The main impact of this work is the harnessing of biological RCs for efficient energy harvesting in man-made structures. Specifically, the results in this work will advance the application of RCs in devices for energy harvesting and will enable a better understanding of bio and nanomaterial interfaces, thereby advancing the application of biological materials in electronic devices. At the end, this work offers general guidelines that can serve to improve the performance of bio-hybrid solar cells.

Nanocrystal solar cells processed from solution

DOEpatents

Alivisatos, A. Paul; Gur, Ilan; Milliron, Delia

2013-05-14

A photovoltaic device having a first electrode layer, a high resistivity transparent film disposed on the first electrode, a second electrode layer, and an inorganic photoactive layer disposed between the first and second electrode layers, wherein the inorganic photoactive layer is disposed in at least partial electrical contact with the high resistivity transparent film, and in at least partial electrical contact with the second electrode. The photoactive layer has a first inorganic material and a second inorganic material different from the first inorganic material, wherein the first and second inorganic materials exhibit a type II band offset energy profile, and wherein the photoactive layer has a first population of nanostructures of a first inorganic material and a second population of nanostructures of a second inorganic material.

Effects of addition of different carbon materials on the electrochemical performance of nickel hydroxide electrode

NASA Astrophysics Data System (ADS)

Sierczynska, Agnieszka; Lota, Katarzyna; Lota, Grzegorz

Nickel hydroxide is used as an active material in positive electrodes of rechargeable alkaline batteries. The capacity of nickel-metal hydride (Ni-MH) batteries depends on the specific capacity of the positive electrode and utilization of the active material because of the Ni(OH) 2/NiOOH electrode capacity limitation. The practical capacity of the positive nickel electrode depends on the efficiency of the conductive network connecting the Ni(OH) 2 particle with the current collector. As β-Ni(OH) 2 is a kind of semiconductor, the additives are necessary to improve the conductivity between the active material and the current collector. In this study the effect of adding different carbon materials (flake graphite, multi-walled carbon nanotubes (MWNT)) on the electrochemical performance of pasted nickel-foam electrode was established. A method of production of MWNT special type of catalysts had an influence on the performance of the nickel electrodes. The electrochemical tests showed that the electrode with added MWNT (110-170 nm diameter) exhibited better electrochemical properties in the chargeability, specific discharge capacity, active material utilization, discharge voltage and cycling stability. The nickel electrodes with MWNT addition (110-170 nm diameter) have exhibited a specific capacity close to 280 mAh g -1 of Ni(OH) 2, and the degree of active material utilization was ∼96%.

Optimization of the Negative Electrode in Organic Photovoltaic Devices

NASA Astrophysics Data System (ADS)

Reese, Matthew; White, Matthew; Rumbles, Garry; Ginley, David; Shaheen, Sean

2007-03-01

A blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) is used as the active layer in a series of bulk heterojunction organic solar cells. This polymer blend serves as a test-bed to explore the significant effects on device performance of using low work function metals and/or alkali metal halides as the top, negative electrode. Work function values reported in the literature are compared with those measured for our thin films. A series of contact materials are investigated including Al, Ca/Al, Ba/Al, LiF/Al; many devices are prepared with each contact type to validate the statistical significance of the results.

Method of fabricating electrodes including high-capacity, binder-free anodes for lithium-ion batteries

DOEpatents

Ban, Chunmei; Wu, Zhuangchun; Dillon, Anne C.

2017-01-10

An electrode (110) is provided that may be used in an electrochemical device (100) such as an energy storage/discharge device, e.g., a lithium-ion battery, or an electrochromic device, e.g., a smart window. Hydrothermal techniques and vacuum filtration methods were applied to fabricate the electrode (110). The electrode (110) includes an active portion (140) that is made up of electrochemically active nanoparticles, with one embodiment utilizing 3d-transition metal oxides to provide the electrochemical capacity of the electrode (110). The active material (140) may include other electrochemical materials, such as silicon, tin, lithium manganese oxide, and lithium iron phosphate. The electrode (110) also includes a matrix or net (170) of electrically conductive nanomaterial that acts to connect and/or bind the active nanoparticles (140) such that no binder material is required in the electrode (110), which allows more active materials (140) to be included to improve energy density and other desirable characteristics of the electrode. The matrix material (170) may take the form of carbon nanotubes, such as single-wall, double-wall, and/or multi-wall nanotubes, and be provided as about 2 to 30 percent weight of the electrode (110) with the rest being the active material (140).

Electrode Induced Removal and Recovery of Uranium (VI) from Acidic Subsurfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gregory, Kelvin

2013-08-12

The overarching objective of this research is to provide an improved understanding of how aqueous geochemical conditions impact the removal of U and Tc from groundwater and how engineering design may be utilized to optimize removal of these radionuclides. Experiments were designed to address the unique conditions in Area 3 of ORNL while also providing broader insight into the geochemical effectors of the removal rates and extent for U and Tc. The specific tasks of this work were to: 1) quantify the impact of common aqueous geochemical and operational conditions on the rate and extent of U removal and recoverymore » from water, 2) investigate the removal of Tc with polarized graphite electrode, and determine the influence of geochemical and operational conditions on Tc removal and recovery, 3) determine whether U and Tc may be treated simultaneous from Area 3 groundwater, and examine the bench-scale performance of electrode-based treatment, and 4) determine the capacity of graphite electrodes for U(VI) removal and develop a mathematical, kinetic model for the removal of U(VI) from aqueous solution. Overall the body of work suggests that an electrode-based approach for the remediation of acidic subsurface environments, such as those observed in Area 3 of ORNL may be successful for the removal for both U(VI) and Tc. Carbonaceous (graphite) electrode materials are likely to be the least costly means to maximize removal rates and efficiency by maximizing the electrode surface area.« less

Electrochemical cell method

DOEpatents

Kaun, T.D.; Eshman, P.F.

1980-05-09

A secondary electrochemical cell is prepared by providing positive and negative electrodes having outer enclosures of rigid perforated electrically conductive material defining an internal compartment containing the electrode material in porous solid form. The electrodes are each immersed in molten electrolyte salt prior to cell assembly to incorporate the cell electrolyte. Following solidification of the electrolyte substantially throughout the porous volume of the electrode material, the electrodes are arranged in an alternating positive-negative array with interelectrode separators of porous frangible electrically insulative material. The completed array is assembled into the cell housing and sealed such that on heating the solidified electrolyte flows into the interelectrode separator.

Extrusion of electrode material by liquid injection into extruder barrel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keller, David Gerard; Giovannoni, Richard Thomas; MacFadden, Kenneth Orville

An electrode sheet product is formed using an extruder having a feed throat and a downstream section by separately mixing an active electrode material and a solid polymer electrolyte composition that contains lithium salt. The active electrode material is fed into the feed throat of the extruder, while a portion of at least one fluid component of the solid polymer electrolyte composition is introduced to the downstream section. The active electrode material and the solid polymer electrolyte composition are compounded in a downstream end of the extruder. The extruded sheets, adhered to current collectors, can be formed into battery cells.

Fabrication of hollow nanorod electrodes based on RuO2//Fe2O3 for an asymmetric supercapacitor.

PubMed

Wang, Qiufan; Liang, Xiao; Ma, Yun; Zhang, Daohong

2018-06-12

In this work, hollow RuO2 nanotube arrays were successfully grown on carbon cloth by using a facile two-step method to fabricate a binder-free electrode. The well-aligned electrode displays excellent electrochemical performance. By using RuO2 hollow nanotube arrays as the positive electrode and Fe2O3 as the negative electrode, a flexible solid-state asymmetric supercapacitor (ASC) has been fabricated which exhibited excellent electrochemical performance, such as a high capacitance of 4.9 F cm-3, a high energy density of 1.5 mW h cm-3 and a high power density of 9.1 mW cm-3. In addition, the two-electrode SC shows high cycling stability with 97% capacitance retention after 5000 charge-discharge cycles. These excellent electrochemical performances are ascribed to the unique hollow structural design of electrodes, which can shorten the ion diffusion length, provide a fast ion transport channel, and offer a large electrode/electrolyte interface for the charge-transfer reaction. The structural design and the synthesis approach are general and can be extended to synthesizing a broad range of materials systems.

Organic solar cells with graphene electrodes and vapor printed poly(3,4-ethylenedioxythiophene) as the hole transporting layers.

PubMed

Park, Hyesung; Howden, Rachel M; Barr, Miles C; Bulović, Vladimir; Gleason, Karen; Kong, Jing

2012-07-24

For the successful integration of graphene as a transparent conducting electrode in organic solar cells, proper energy level alignment at the interface between the graphene and the adjacent organic layer is critical. The role of a hole transporting layer (HTL) thus becomes more significant due to the generally lower work function of graphene compared to ITO. A commonly used HTL material with ITO anodes is poly(3,4-ethylenedioxythiophene) (PEDOT) with poly(styrenesulfonate) (PSS) as the solid-state dopant. However, graphene's hydrophobic surface renders uniform coverage of PEDOT:PSS (aqueous solution) by spin-casting very challenging. Here, we introduce a novel, yet simple, vapor printing method for creating patterned HTL PEDOT layers directly onto the graphene surface. Vapor printing represents the implementation of shadow masking in combination with oxidative chemical vapor deposition (oCVD). The oCVD method was developed for the formation of blanket (i.e., unpatterened) layers of pure PEDOT (i.e., no PSS) with systematically variable work function. In the unmasked regions, vapor printing produces complete, uniform, smooth layers of pure PEDOT over graphene. Graphene electrodes were synthesized under low-pressure chemical vapor deposition (LPCVD) using a copper catalyst. The use of another electron donor material, tetraphenyldibenzoperiflanthene, instead of copper phthalocyanine in the organic solar cells also improves the power conversion efficiency. With the vapor printed HTL, the devices using graphene electrodes yield comparable performances to the ITO reference devices (η(p,LPCVD) = 3.01%, and η(p,ITO) = 3.20%).

Bulk-Type All-Solid-State Lithium-Ion Batteries: Remarkable Performances of a Carbon Nanofiber-Supported MgH2 Composite Electrode.

PubMed

Zeng, Liang; Ichikawa, Takayuki; Kawahito, Koji; Miyaoka, Hiroki; Kojima, Yoshitsugu

2017-01-25

Magnesium hydride, MgH 2 , a recently developed compound for lithium-ion batteries, is considered to be a promising conversion-type negative electrode material due to its high theoretical lithium storage capacity of over 2000 mA h g -1 , suitable working potential, and relatively small volume expansion. Nevertheless, it suffers from unsatisfactory cyclability, poor reversibility, and slow kinetics in conventional nonaqueous electrolyte systems, which greatly limit the practical application of MgH 2 . In this work, a vapor-grown carbon nanofiber was used to enhance the electrical conductivity of MgH 2 using LiBH 4 as the solid-state electrolyte. It shows that a reversible capacity of over 1200 mA h g -1 with an average voltage of 0.5 V (vs Li/Li + ) can be obtained after 50 cycles at a current density of 1000 mA g -1 . In addition, the capacity of MgH 2 retains over 1100 mA h g -1 at a high current density of 8000 mA g -1 , which indicates the possibility of using MgH 2 as a negative electrode material for high power and high capacity lithium-ion batteries in future practical applications. Moreover, the widely studied sulfide-based solid electrolyte was also used to assemble battery cells with MgH 2 electrode in the same system, and the electrochemical performance was as good as that using LiBH 4 electrolyte.

Point-of-need simultaneous electrochemical detection of lead and cadmium using low-cost stencil-printed transparency electrodes.

PubMed

Martín-Yerga, Daniel; Álvarez-Martos, Isabel; Blanco-López, M Carmen; Henry, Charles S; Fernández-Abedul, M Teresa

2017-08-15

In this work, we report a simple and yet efficient stencil-printed electrochemical platform that can be integrated into the caps of sample containers and thus, allows in-field quantification of Cd(II) and Pb(II) in river water samples. The device exploits the low-cost features of carbon (as electrode material) and paper/polyester transparency sheets (as substrate). Electrochemical analysis of the working electrodes prepared on different substrates (polyester transparency sheets, chromatographic, tracing and office papers) with hexaammineruthenium(III) showed that their electroactive area and electron transfer kinetics are highly affected by the porosity of the material. Electrodes prepared on transparency substrates showed the best electroanalytical performance for the simultaneous determination of Cd(II) and Pb(II) by square-wave anodic stripping voltammetry. Interestingly, the temperature and time at which the carbon ink was cured had significant effect on the electrochemical response, especially the capacitive current. The amount of Cd and Pb on the electrode surface can be increased about 20% by in situ electrodeposition of bismuth. The electrochemical platform showed a linear range comprised between 1 and 200 μg/L for both metals, sensitivity of analysis of 0.22 and 0.087 μA/ppb and limits of detection of 0.2 and 0.3 μg/L for Cd(II) and Pb(II), respectively. The analysis of river water samples was done directly in the container where the sample was collected, which simplifies the procedure and approaches field analysis. The developed point-of-need detection system allowed simultaneous determination of Cd(II) and Pb(II) in those samples using the standard addition method with precise and accurate results. Copyright © 2017 Elsevier B.V. All rights reserved.

Recent advances in material science for developing enzyme electrodes.

PubMed

Sarma, Anil Kumar; Vatsyayan, Preety; Goswami, Pranab; Minteer, Shelley D

2009-04-15

The enzyme-modified electrode is the fundamental component of amperometric biosensors and biofuel cells. The selection of appropriate combinations of materials, such as: enzyme, electron transport mediator, binding and encapsulation materials, conductive support matrix and solid support, for construction of enzyme-modified electrodes governs the efficiency of the electrodes in terms of electron transfer kinetics, mass transport, stability, and reproducibility. This review investigates the varieties of materials that can be used for these purposes. Recent innovation in conductive electro-active polymers, functionalized polymers, biocompatible composite materials, composites of transition metal-based complexes and organometallic compounds, sol-gel and hydro-gel materials, nanomaterials, other nano-metal composites, and nano-metal oxides are reviewed and discussed here. In addition, the critical issues related to the construction of enzyme electrodes and their application for biosensor and biofuel cell applications are also highlighted in this article. Effort has been made to cover the recent literature on the advancement of materials sciences to develop enzyme electrodes and their potential applications for the construction of biosensors and biofuel cells.

Hydrogen-based electrochemical energy storage

DOEpatents

Simpson, Lin Jay

2013-08-06

An energy storage device (100) providing high storage densities via hydrogen storage. The device (100) includes a counter electrode (110), a storage electrode (130), and an ion conducting membrane (120) positioned between the counter electrode (110) and the storage electrode (130). The counter electrode (110) is formed of one or more materials with an affinity for hydrogen and includes an exchange matrix for elements/materials selected from the non-noble materials that have an affinity for hydrogen. The storage electrode (130) is loaded with hydrogen such as atomic or mono-hydrogen that is adsorbed by a hydrogen storage material such that the hydrogen (132, 134) may be stored with low chemical bonding. The hydrogen storage material is typically formed of a lightweight material such as carbon or boron with a network of passage-ways or intercalants for storing and conducting mono-hydrogen, protons, or the like. The hydrogen storage material may store at least ten percent by weight hydrogen (132, 134) at ambient temperature and pressure.

Surface Chemistry and Precursor Material Effects on the Performance of Pyrolyzed Nanofibers as Anodes for Lithium-ion Batteries

NASA Astrophysics Data System (ADS)

Loebl, Andrew James

Next-generation lithium-ion batteries to meet consumer demands and new applications require the development of new electrode materials. Electrospinning of polymers is a simple and effective method to create one-dimensional, self-supporting materials, with no inactive components after pyrolysis. Composites of these nanofibers and high-capacity lithium materials have been demonstrated to possess superior reversible capacity than state-of-the-art commercial anodes. Despite impressive reversible discharge capacities polyacrylonitrile-based composites are not ready for adoption in commercial applications. These materials suffer from irreversible losses of Li to formation on the electrode of the solid electrolyte interphase during the first charge of the cell. This thesis work has taken two approaches to engineer high-performing nanofiber-based electrodes. First, the chemistry at the interface of the electrode and the electrolyte has been changed by depositing new surfaces. Attempts to create a graphitic fiber surface via plasma enhanced chemical vapor deposition did not result in an improvement of the irreversible losses. However, the experiments did demonstrate the growth of large surface area carbon nanowalls on the pyrolyzed electrospun fibers, creating a material which could serve as a substrate in catalysis or as an electrode for composite ultra-capacitors. Additionally, passivation surfaces were deposited by atomic layer deposition and molecular layer deposition. These new surfaces were employed to reduce the irreversible consumption of lithium by moving the charge transfer reaction to the interface of the carbon and the new material. The removal the lithium from the solvent prior to charge transfer limits the irreversible reduction of solvent by metallic lithium. Alumina films grown by atomic layer deposition reduced lithium losses to the solid electrolyte interphase by up to 42% for twenty deposition cycles. This large improvement in irreversible capacity resulted in a nearly 50% reduction in reversible lithium storage. Thinner coatings of alumina had a less dramatic effect on both the irreversible capacity losses and the reversible discharge capacity. A coating of ten cycles of alumina at a temperature of 150 °C resulted in a 17% reduction in irreversible capacity with negligible impact on the reversible capacity. Hybrid aluminum-organic films grown by molecular layer deposition also reduced irreversible lithium losses. The largest reduction was 23% for electrodes coated with 40 cycles of the alucone material. For all thicknesses studied these hybrid films delivered less improvement than the alumina grown by atomic layer deposition, with poor reversible lithium storage capacity available at high charging and discharging currents. Second, polyacrylonitrile has served as the precursor for electrospun composite electrodes because of its ease of processing and well-known carbonization process. Polyimides represent a family of polymers for which the material properties can be tailored by careful monomer selection. These polymers were used as the non-woven matrix to create materials capable of delivering a larger percentage of their maximum reversible capacities at high currents when compared to polyacrylonitrile-based electrodes. These materials had a more graphitic structure based on Raman spectroscopy, and resulted in lower irreversible capacity losses than polyacrylonitrile-based fibers for fibers based on pyromellitic dianhydride and p-phenylene diamine.

Recirculating electric air filter

DOEpatents

Bergman, Werner

1986-01-01

An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors

PubMed Central

2017-01-01

The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest. PMID:28745040

Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors.

PubMed

Torabi, Solmaz; Cherry, Megan; Duijnstee, Elisabeth A; Le Corre, Vincent M; Qiu, Li; Hummelen, Jan C; Palasantzas, George; Koster, L Jan Anton

2017-08-16

The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest.

Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doe, Robert E.; Downie, Craig M.; Fischer, Christopher

2016-01-19

Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negativemore » electrode active material is described.« less

Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher

2016-07-26

Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negativemore » electrode active material is described.« less

Lithium potential variations for metastable materials: case study of nanocrystalline and amorphous LiFePO4.

PubMed

Zhu, Changbao; Mu, Xiaoke; Popovic, Jelena; Weichert, Katja; van Aken, Peter A; Yu, Yan; Maier, Joachim

2014-09-10

Much attention has been paid to metastable materials in the lithium battery field, especially to nanocrystalline and amorphous materials. Nonetheless, fundamental issues such as lithium potential variations have not been pertinently addressed. Using LiFePO4 as a model system, we inspect such lithium potential variations for various lithium storage modes and evaluate them thermodynamically. The conclusions of this work are essential for an adequate understanding of the behavior of electrode materials and even helpful in the search for new energy materials.

Roll-to-roll light directed electrophoretic deposition system and method

DOEpatents

Pascall, Andrew J.; Kuntz, Joshua

2017-06-06

A roll-to-roll light directed electrophoretic deposition system and method advances a roll of a flexible electrode web substrate along a roll-to-roll process path, where a material source is positioned to provide on the flexible electrode web substrate a thin film colloidal dispersion of electrically charged colloidal material dispersed in a fluid. A counter electrode is also positioned to come in contact with the thin film colloidal dispersion opposite the flexible electrode web substrate, where one of the counter electrode and the flexible electrode web substrate is a photoconductive electrode. A voltage source is connected to produce an electric potential between the counter electrode and the flexible electrode web substrate to induce electrophoretic deposition on the flexible electrode web substrate when the photoconductive electrode is rendered conductive, and a patterned light source is arranged to illuminate the photoconductive electrode with a light pattern and render conductive illuminated areas of the photoconductive electrode so that a patterned deposit of the electrically charged colloidal material is formed on the flexible electrode web substrate.

Method of making electrodes for electrochemical cell. [Li-Al alloy

DOEpatents

Kaun, T.D.; Kilsdonk, D.J.

1981-07-29

A method is described for making an electrode for an electrochemical cell in which particulate electrode-active material is mixed with a liquid organic carrier chemically inert with respect to the electrode-active material, mixing the liquid carrier to form an extrudable slurry. The liquid carrier is present in an amount of from about 10 to about 50% by volume of the slurry, and then the carrier is removed from the slurry leaving the electrode-active material. The method is particularly suited for making a lithium-aluminum alloy negative electrode for a high-temperature cell.

Final Report. Novel Behavior of Ferromagnet/Superconductor Hybrid Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birge, Norman

Final report for grant DE-FG02-06ER46341. This work has produced a most convincing experimental demonstration that spin-triplet supercurrent can appear in Josephson junctions containing ferromagnetic materials, even when the superconducting electrodes are conventional, spin-singlet superconductors.

Influence of Electrical Resistivity and Machining Parameters on Electrical Discharge Machining Performance of Engineering Ceramics

PubMed Central

Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

2014-01-01

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al2O3 ceramic. PMID:25364912

Rotational magneto-acousto-electric tomography (MAET): theory and experimental validation

PubMed Central

Kunyansky, L; Ingram, C P; Witte, R S

2017-01-01

We present a novel two-dimensional (2D) MAET scanner, with a rotating object of interest and two fixed pairs of electrodes. Such an acquisition scheme, with our novel reconstruction techniques, recovers the boundaries of the regions of constant conductivity uniformly well, regardless of their orientation. We also present a general image reconstruction algorithm for the 2D MAET in a circular chamber with point-like electrodes immersed into the saline surrounding the object. An alternative linearized reconstruction procedure is developed, suitable for recovering the material interfaces (boundaries) when a non-ideal piezoelectric transducer is used for acoustic excitation. The work of the scanner and the linearized reconstruction algorithm is demonstrated using several phantoms made of high-contrast materials and a biological sample. PMID:28323633

Materials Science of Electrodes and Interfaces for High-Performance Organic Photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marks, Tobin

The science of organic photovoltaic (OPV) cells has made dramatic advances over the past three years with power conversion efficiencies (PCEs) now reaching ~12%. The upper PCE limit of light-to-electrical power conversion for single-junction OPVs as predicted by theory is ~23%. With further basic research, the vision of such devices, composed of non-toxic, earth-abundant, readily easily processed materials replacing/supplementing current-generation inorganic solar cells may become a reality. Organic cells offer potentially low-cost, roll-to-roll manufacturable, and durable solar power for diverse in-door and out-door applications. Importantly, further gains in efficiency and durability, to that competitive with inorganic PVs, will require fundamental,more » understanding-based advances in transparent electrode and interfacial materials science and engineering. This team-science research effort brought together an experienced and highly collaborative interdisciplinary group with expertise in hard and soft matter materials chemistry, materials electronic structure theory, solar cell fabrication and characterization, microstructure characterization, and low temperature materials processing. We addressed in unconventional ways critical electrode-interfacial issues underlying OPV performance -- controlling band offsets between transparent electrodes and organic active-materials, addressing current loss/leakage phenomena at interfaces, and new techniques in cost-effective low temperature and large area cell fabrication. The research foci were: 1) Theory-guided design and synthesis of advanced crystalline and amorphous transparent conducting oxide (TCO) layers which test our basic understanding of TCO structure-transport property relationships, and have high conductivity, transparency, and tunable work functions but without (or minimizing) the dependence on indium. 2) Development of theory-based understanding of optimum configurations for the interfaces between oxide electrodes/interfacial layers and OPV active layer organic molecules/polymers. 3) Exploration and perfection of new processing strategies and cell architectures for the next-generation, large-area flexible OPVs. The goal has been to develop for the solar energy community the fundamental scientific understanding needed to design, fabricate, prototype, and ultimately test high-efficiency cells incorporating these new concepts. We achieved success in all of these directions.« less

CO₂ and O₂ evolution at high voltage cathode materials of Li-ion batteries: a differential electrochemical mass spectrometry study.

PubMed

Wang, Hongsen; Rus, Eric; Sakuraba, Takahito; Kikuchi, Jun; Kiya, Yasuyuki; Abruña, Héctor D

2014-07-01

A three-electrode differential electrochemical mass spectrometry (DEMS) cell has been developed to study the oxidative decomposition of electrolytes at high voltage cathode materials of Li-ion batteries. In this DEMS cell, the working electrode used was the same as the cathode electrode in real Li-ion batteries, i.e., a lithium metal oxide deposited on a porous aluminum foil current collector. A charged LiCoO2 or LiMn2O4 was used as the reference electrode, because of their insensitivity to air, when compared to lithium. A lithium sheet was used as the counter electrode. This DEMS cell closely approaches real Li-ion battery conditions, and thus the results obtained can be readily correlated with reactions occurring in real Li-ion batteries. Using DEMS, the oxidative stability of three electrolytes (1 M LiPF6 in EC/DEC, EC/DMC, and PC) at three cathode materials including LiCoO2, LiMn2O4, and LiNi(0.5)Mn(1.5)O4 were studied. We found that 1 M LiPF6 + EC/DMC electrolyte is quite stable up to 5.0 V, when LiNi(0.5)Mn(1.5)O4 is used as the cathode material. The EC/DMC solvent mixture was found to be the most stable for the three cathode materials, while EC/DEC was the least stable. The oxidative decomposition of the EC/DEC mixture solvent could be readily observed under operating conditions in our cell even at potentials as low as 4.4 V in 1 M LiPF6 + EC/DEC electrolyte on a LiCoO2 cathode, as indicated by CO2 and O2 evolution. The features of this DEMS cell to unveil solvent and electrolyte decomposition pathways are also described.

Graphene-conducting polymer nanocomposite as novel electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Gómez, Humberto; Ram, Manoj K.; Alvi, Farah.; Villalba, P.; Stefanakos, Elias (Lee); Kumar, Ashok

A novel graphene-polyaniline nanocomposite material synthesized using chemical precipitation technique is reported as an electrode for supercapacitors. The graphene (G)-polyaniline (PANI) nanocomposite film was dissolved in N-Methyl-2-pyrrolidone (NMP) and characterized using Raman, FTIR, Scanning Electron Microscopy, Transmission Electron Microscopy, and cyclic voltammetry (CV) techniques. The interesting composite structure could be observed using different ratios of graphene and aniline monomer. The supercapacitor is fabricated using G-PANI in N-Methyl-2-pyrrolidone (NMP) and G-PANI-Nafion films on graphite electrodes. A specific capacitance of 300-500 F g -1 at a current density of 0.1 A g -1 is observed over graphene-PANI nanocomposite materials. The aim of this study is to tailor the properties of the capacitors through the optimization of their components, and packaging towards a qualification for portable systems applications. Based on experimental data shown in this work, conducting polymer nanocomposite capacitor technology could be viable, and could also surpass existing technologies when such a novel approach is used.

Detection of mercury ions using L-cysteine modified electrodes by anodic stripping voltammetric method

NASA Astrophysics Data System (ADS)

Vanitha, M.; Balasubramanian, N.; Joni, I. Made; Panatarani, Camellia

2018-02-01

The detection of contaminants in wastewater is of massive importance in today's situation as they pose a serious threat to the environment as well as humans. One such vital contaminants is mercury and its compound, the reported mercury detectors grieve from low sensitivity, high cost and slow response. In the present work graphene based electrode material is developed for sensing mercury contaminants in wastewater using electrochemical technique. The synthesized material graphene oxide (GO) modified with L-Cysteine in presence of polyvinylpyrrolidone (PVP) as capping agent was characterized using SEM, TEM and Raman Spectroscopic analysis. It is ascertained from the morphological characterization that the nanocomposite exhibits a spherical morphology. The L-cysteine modified graphene oxide electrode is electrochemically characterized using redox couple [Fe(CN)63-/4-] and electrochemical impedance spectroscopic (EIS) analysis. Electrochemical sensing of Hg (II) ions in solution was done using Square wave anodic stripping voltammetry (SWASV). The incorporation of graphene significantly increases the sensitivity and selectivity towards mercury sensing.

Direct view on the phase evolution in individual LiFePO4 nanoparticles during Li-ion battery cycling.

PubMed

Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P; Brownrigg, Alex; Wright, Jonathan P; van Dijk, Niels H; Wagemaker, Marnix

2015-09-23

Phase transitions in Li-ion electrode materials during (dis)charge are decisive for battery performance, limiting high-rate capabilities and playing a crucial role in the cycle life of Li-ion batteries. However, the difficulty to probe the phase nucleation and growth in individual grains is hindering fundamental understanding and progress. Here we use synchrotron microbeam diffraction to disclose the cycling rate-dependent phase transition mechanism within individual particles of LiFePO4, a key Li-ion electrode material. At low (dis)charge rates well-defined nanometer thin plate-shaped domains co-exist and transform much slower and concurrent as compared with the commonly assumed mosaic transformation mechanism. As the (dis)charge rate increases phase boundaries become diffuse speeding up the transformation rates of individual grains. Direct observation of the transformation of individual grains reveals that local current densities significantly differ from what has previously been assumed, giving new insights in the working of Li-ion battery electrodes and their potential improvements.

Direct view on the phase evolution in individual LiFePO4 nanoparticles during Li-ion battery cycling

PubMed Central

Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P.; Brownrigg, Alex; Wright, Jonathan P.; van Dijk, Niels H.; Wagemaker, Marnix

2015-01-01

Phase transitions in Li-ion electrode materials during (dis)charge are decisive for battery performance, limiting high-rate capabilities and playing a crucial role in the cycle life of Li-ion batteries. However, the difficulty to probe the phase nucleation and growth in individual grains is hindering fundamental understanding and progress. Here we use synchrotron microbeam diffraction to disclose the cycling rate-dependent phase transition mechanism within individual particles of LiFePO4, a key Li-ion electrode material. At low (dis)charge rates well-defined nanometer thin plate-shaped domains co-exist and transform much slower and concurrent as compared with the commonly assumed mosaic transformation mechanism. As the (dis)charge rate increases phase boundaries become diffuse speeding up the transformation rates of individual grains. Direct observation of the transformation of individual grains reveals that local current densities significantly differ from what has previously been assumed, giving new insights in the working of Li-ion battery electrodes and their potential improvements. PMID:26395323

Evaluation of in-channel amperometric detection using a dual-channel microchip electrophoresis device and a two-electrode potentiostat for reverse polarity separations

PubMed Central

Meneses, Diogenes; Gunasekara, Dulan B.; Pichetsurnthorn, Pann; da Silva, José A. F.; de Abreu, Fabiane C.; Lunte, Susan M.

2015-01-01

In-channel amperometric detection combined with dual-channel microchip electrophoresis is evaluated using a two-electrode isolated potentiostat for reverse polarity separations. The device consists of two separate channels with the working and reference electrodes placed at identical positions relative to the end of the channel, enabling noise subtraction. In previous reports of this configuration, normal polarity and a three-electrode detection system were used. In the two-electrode detection system described here, the electrode in the reference channel acts as both the counter and reference. The effect of electrode placement in the channels on noise and detector response was investigated using nitrite, tyrosine, and hydrogen peroxide as model compounds. The effects of electrode material and size and type of reference electrode on noise and the potential shift of hydrodynamic voltammograms for the model compounds were determined. In addition, the performance of two- and three-electrode configurations using Pt and Ag/AgCl reference electrodes was compared. Although the signal was attenuated with the Pt reference, the noise was also significantly reduced. It was found that lower LOD were obtained for all three compounds with the dual-channel configuration compared to single-channel, in-channel detection. The dual-channel method was then used for the detection of nitrite in a dermal microdialysis sample obtained from a sheep following nitroglycerin administration. PMID:25256669

Advanced thermionic converter development

NASA Technical Reports Server (NTRS)

Huffman, F. N.; Lieb, D.; Briere, T. R.; Sommer, A. H.; Rufeh, F.

1976-01-01

Recent progress at Thermo Electron in developing advanced thermionic converters is summarized with particular attention paid to the development of electrodes, diodes, and triodes. It is found that one class of materials (ZnO, BaO and SrO) provides interesting cesiated work functions (1.3-1.4 eV) without additional oxygen. The second class of materials studied (rare earth oxides and hexaborides) gives cesiated/oxygenated work functions of less than 1.2 eV. Five techniques of oxygen addition to thermionic converters are discussed. Vapor deposited tungsten oxide collector diodes and the reflux converter are considered.

Electro-catalytic biodiesel production from canola oil in methanolic and ethanolic solutions with low cost stainless steel and hybrid ion-exchange resin grafted electrodes

NASA Astrophysics Data System (ADS)

Allioux, Francois-Marie; Holland, Brendan J.; Kong, Lingxue; Dumée, Ludovic F.

2017-07-01

Biodiesel is a growing alternative to petroleum fuels and is produced by the catalysed transesterification of fats in presence of an alcohol base. Transesterification processes using homogeneous catalysts are considered to be amongst the most efficient methods but rely on the feedstock quality and low water content in order to avoid undesirable saponification reactions. In this work, the electro-catalytic conversion of canola oil to biodiesel in a 1% aqueous methanolic and ethanolic reaction mixture was performed without the addition of external catalyst or co-solvent. An inexpensive stainless steel electrode and a hybrid stainless steel electrode coated with an ion-exchange resin catalyst were used as cathode materials while the anode was composed of a plain carbon paper. The cell voltages were varied from 10 to 40 V and the reaction temperature maintained at 20 or 40°C. The canola oil conversion rates were found to be superior at 40°C without saponification reactions for cell voltages below 30 V. The conversion rates were as high as 87% for the hybrid electrode and 81% for the plain stainless steel electrode. This work could inspire new process development for the conversion of high water content feedstock for the production of second-generation biodiesel.

Design of activated carbon/activated carbon asymmetric capacitors

NASA Astrophysics Data System (ADS)

Piñeiro-Prado, Isabel; Salinas-Torres, David; Ruiz Rosas, Ramiro; Morallon, Emilia; Cazorla-Amoros, Diego

2016-03-01

Supercapacitors are energy storage devices that offer a high power density and a low energy density in comparison with batteries. Their limited energy density can be overcome by using asymmetric configuration in mass electrodes, where each electrode works within their maximum available potential window, rendering the maximum voltage output of the system. Such asymmetric capacitors must be optimized through careful electrochemical characterization of the electrodes for accurate determination of the capacitance and the potential stability limits. The results of the characterization are then used for optimizing mass ratio of the electrodes from the balance of stored charge. The reliability of the design largely depends on the approach taken for the electrochemical characterization. Therefore, the performance could be lower than expected and even the system could break down, if a well thought out procedure is not followed. In this work, a procedure for the development of asymmetric supercapacitors based on activated carbons is detailed. Three activated carbon materials with different textural properties and surface chemistry have been systematically characterized in neutral aqueous electrolyte. The asymmetric configuration of the masses of both electrodes in the supercapacitor has allowed to cover a higher potential window, resulting in an increase of the energy density of the three devices studied when compared with the symmetric systems, and an improved cycle life.

Electrochemical cell with powdered electrically insulative material as a separator

DOEpatents

Mathers, James P.; Olszanski, Theodore W.; Boquist, Carl W.

1978-01-01

A secondary electrochemical cell includes electrodes separated by a layer of electrically insulative powder. The powder includes refractory materials selected from the oxides and nitrides of metals and metaloids. The powdered refractory material, blended with electrolyte particles, can be compacted in layers with electrode materials to form an integral electrode structure or separately assembled into the cell. The assembled cell is heated to operating temperature leaving porous layers of electrically insulative, refractory particles, containing molten electrolyte between the electrodes.

Biotic and abiotic characterization of bioanodes formed on oxidized carbon electrodes as a basis to predict their performance.

PubMed

Cercado, Bibiana; Cházaro-Ruiz, Luis Felipe; Ruiz, Vianey; López-Prieto, Israel de Jesús; Buitrón, Germán; Razo-Flores, Elías

2013-12-15

Bioelectrochemical systems (BESs) are based on the catalytic activity of biofilm on electrodes, or the so-called bioelectrodes, to produce electricity and other valuable products. In order to increase bioanode performance, diverse electrode materials and modification methods have been implemented; however, the factors directly affecting performance are yet unclear. In this work carbon cloth electrodes were modified by thermal, chemical, and electrochemical oxidation to enhance oxygenated surface groups, to modify the electrode texture, and consequently the electron transfer rate and biofilm adhesion. The oxidized electrodes were physically, chemically, and electrochemically characterized, then bioanodes were formed at +0.1 V vs. Ag/AgCl using domestic wastewater amended with acetate. The bioanode performance was evaluated according to the current and charge generated. The efficacy of the treatments were in the order Thermal>Electrochemical>Untreated>Chemical oxidation. The maximum current observed with untreated electrode was 0.152±0.026 mA (380±92 mA m(-2)), and it was increased by 78% and 28% with thermal and electrochemical oxidized electrodes, respectively. Moreover, the volatile solids correlated significantly with the maximum current obtained, and the electrode texture was revealed as a critical factor for increasing the bioanode performance. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis and Modeling of Boundary Layer Separation Method (BLSM).

PubMed

Pethő, Dóra; Horváth, Géza; Liszi, János; Tóth, Imre; Paor, Dávid

2010-09-01

Nowadays rules of environmental protection strictly regulate pollution material emission into environment. To keep the environmental protection laws recycling is one of the useful methods of waste material treatment. We have developed a new method for the treatment of industrial waste water and named it boundary layer separation method (BLSM). We apply the phenomena that ions can be enriched in the boundary layer of the electrically charged electrode surface compared to the bulk liquid phase. The main point of the method is that the boundary layer at correctly chosen movement velocity can be taken out of the waste water without being damaged, and the ion-enriched boundary layer can be recycled. Electrosorption is a surface phenomenon. It can be used with high efficiency in case of large electrochemically active surface of electrodes. During our research work two high surface area nickel electrodes have been prepared. The value of electrochemically active surface area of electrodes has been estimated. The existence of diffusion part of the double layer has been experimentally approved. The electrical double layer capacity has been determined. Ion transport by boundary layer separation has been introduced. Finally we have tried to estimate the relative significance of physical adsorption and electrosorption.

Na/beta-alumina/NaAlCl4, Cl2/C circulating cell

NASA Technical Reports Server (NTRS)

Cherng, Jing-Yih; Bennion, Douglas N.

1987-01-01

A study was made of a high specific energy battery based on a sodium negative electrode and a chlorine positive electrode with molten AlCl3-NaCl electrolyte and a solid beta alumina separator. The basic performance of a Na beta-alumina NaAlCl4, Cl2/C circulating cell at 200 C was demonstrated. This cell can be started at 150 C. The use of melting sodium chloroaluminate electrolyte overcomes some of the material problems associated with the high working temperatures of present molten salt systems, such as Na/S and LiAl/FeS, and retains the advantages of high energy density and relatively efficient electrode processes. Preliminary investigations were conducted on a sodium-chlorine static cell, material compability, electrode design, wetting, and theoretical calculations to assure a better chance of success before assembling a Na/Cl2 circulating cell. Mathematical models provide a theoretical explanation for the performance of the NaCl2 battery. The results of mathematical models match the experimental results very well. According to the result of the mathematical modeling, an output at 180 mA/sq cm and 3.2 V can be obtained with optimized cell design.

Combining phase-field crystal methods with a Cahn-Hilliard model for binary alloys

NASA Astrophysics Data System (ADS)

Balakrishna, Ananya Renuka; Carter, W. Craig

2018-04-01

Diffusion-induced phase transitions typically change the lattice symmetry of the host material. In battery electrodes, for example, Li ions (diffusing species) are inserted between layers in a crystalline electrode material (host). This diffusion induces lattice distortions and defect formations in the electrode. The structural changes to the lattice symmetry affect the host material's properties. Here, we propose a 2D theoretical framework that couples a Cahn-Hilliard (CH) model, which describes the composition field of a diffusing species, with a phase-field crystal (PFC) model, which describes the host-material lattice symmetry. We couple the two continuum models via coordinate transformation coefficients. We introduce the transformation coefficients in the PFC method to describe affine lattice deformations. These transformation coefficients are modeled as functions of the composition field. Using this coupled approach, we explore the effects of coarse-grained lattice symmetry and distortions on a diffusion-induced phase transition process. In this paper, we demonstrate the working of the CH-PFC model through three representative examples: First, we describe base cases with hexagonal and square symmetries for two composition fields. Next, we illustrate how the CH-PFC method interpolates lattice symmetry across a diffuse phase boundary. Finally, we compute a Cahn-Hilliard type of diffusion and model the accompanying changes to lattice symmetry during a phase transition process.

A study of room-temperature LixMn1.5Ni0.5O4 solid solutions

PubMed Central

Saravanan, Kuppan; Jarry, Angelique; Kostecki, Robert; Chen, Guoying

2015-01-01

Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature LixMn1.5Ni0.5O4 solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of LixMn1.5Ni0.5O4 (0 ≤ x ≤ 1) cathode material consisting of three cubic phases: LiMn1.5Ni0.5O4 (Phase I), Li0.5Mn1.5Ni0.5O4 (Phase II) and Mn1.5Ni0.5O4 (Phase III). A phase diagram capturing the structural changes as functions of both temperature and Li content was established. The work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance. PMID:25619504

A study of room-temperature Li xMn 1.5Ni 0.5O 4 solid solutions

DOE PAGES

Saravanan, Kuppan; Jarry, Angelique; Kostecki, Robert; ...

2015-01-26

Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature Li xMn 1.5Ni 0.5O 4 solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of Li xMn 1.5Ni 0.5O 4 (0 ≤ x ≤ 1) cathode material consisting of three cubic phases: LiMn 1.5Ni 0.5O 4 (Phase I), Li 0.5Mnmore » 1.5Ni 0.5O 4 (Phase II) and Mn 1.5Ni 0.5O 4 (Phase III). A phase diagram capturing the structural changes as functions of both temperature and Li content was established. In conclusion, the work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance.« less

Novel GO-LaSmO2 Nanocomposite as an Effective Electrode Material for Hydrogen Fuel Cells

NASA Astrophysics Data System (ADS)

El-Amin, Ayman A.; Othman, Abdelhameed M.

2016-04-01

Nano-composites of lanthanum-samarium oxide (LaSmO2) were prepared in the absence and presence of graphene oxide (GO) and characterized as an effective electrode material for hydrogen fuel cells. X-ray and scanning electron microscope investigations revealed grain sizes of 8 nm for LaSmO2 and 12 nm for GO-LaSmO2 composites. The x-ray diffraction pattern showed sharp peaks, indicating a well-crystallized phase indexable to a rhombohedral structure with space group R 3 C , and their structural refinement performed in the hexagonal mode. The ionic conductivity of LaSmO2 was found to be 4.12 × 10-5 S/cm, while in the presence of GO it was enhanced to 5.32 × 10-5 S/cm. The mechanism of conduction in the proposed nano-materials was investigated based on frequency exponent S. The values of S were observed to decrease with increasing temperature. This result was found to be in good agreement with the correlated barrier hopping (CBH) model. The present work revealed GO to be a conductivity enhancer that caused the GO-LaSmO2 composite to be an effective electrode material for hydrogen fuel cells.

Extrusion of electrode material by liquid injection into extruder barrel

DOEpatents

Keller, D.G.; Giovannoni, R.T.; MacFadden, K.O.

1998-03-10

An electrode sheet product is formed using an extruder having a feed throat and a downstream section by separately mixing an active electrode material and a solid polymer electrolyte composition that contains lithium salt. The active electrode material is fed into the feed throat of the extruder, while a portion of at least one fluid component of the solid polymer electrolyte composition is introduced to the downstream section. The active electrode material and the solid polymer electrolyte composition are compounded in a downstream end of the extruder. The extruded sheets, adhered to current collectors, can be formed into battery cells. 1 fig.

Method for manufacturing an electrochemical cell

DOEpatents

Kaun, Thomas D.; Eshman, Paul F.

1982-01-01

A secondary electrochemical cell is prepared by providing positive and negative electrodes having outer enclosures of rigid perforated electrically conductive material defining an internal compartment containing the electrode material in porous solid form. The electrodes are each immersed in molten electrolyte salt prior to cell assembly to incorporate the cell electrolyte. Following solidification of the electrolyte substantially throughout the porous volume of the electrode material, the electrodes are arranged in an alternating positive-negative array with interelectrode separators of porous frangible electrically insulative material. The completed array is assembled into the cell housing and sealed such that on heating the solidified electrolyte flows into the interelectrode separator.

Extrusion of electrode material by liquid injection into extruder barrel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keller, D.G.; Giovannoni, R.T.; MacFadden, K.O.

An electrode sheet product is formed using an extruder having a feed throat and a downstream section by separately mixing an active electrode material and a solid polymer electrolyte composition that contains lithium salt. The active electrode material is fed into the feed throat of the extruder, while a portion of at least one fluid component of the solid polymer electrolyte composition is introduced to the downstream section. The active electrode material and the solid polymer electrolyte composition are compounded in a downstream end of the extruder. The extruded sheets, adhered to current collectors, can be formed into battery cells.more » 1 fig.« less

A Step toward High-Energy Silicon-Based Thin Film Lithium Ion Batteries.

PubMed

Reyes Jiménez, Antonia; Klöpsch, Richard; Wagner, Ralf; Rodehorst, Uta C; Kolek, Martin; Nölle, Roman; Winter, Martin; Placke, Tobias

2017-05-23

The next generation of lithium ion batteries (LIBs) with increased energy density for large-scale applications, such as electric mobility, and also for small electronic devices, such as microbatteries and on-chip batteries, requires advanced electrode active materials with enhanced specific and volumetric capacities. In this regard, silicon as anode material has attracted much attention due to its high specific capacity. However, the enormous volume changes during lithiation/delithiation are still a main obstacle avoiding the broad commercial use of Si-based electrodes. In this work, Si-based thin film electrodes, prepared by magnetron sputtering, are studied. Herein, we present a sophisticated surface design and electrode structure modification by amorphous carbon layers to increase the mechanical integrity and, thus, the electrochemical performance. Therefore, the influence of amorphous C thin film layers, either deposited on top (C/Si) or incorporated between the amorphous Si thin film layers (Si/C/Si), was characterized according to their physical and electrochemical properties. The thin film electrodes were thoroughly studied by means of electrochemical impedance spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. We can show that the silicon thin film electrodes with an amorphous C layer showed a remarkably improved electrochemical performance in terms of capacity retention and Coulombic efficiency. The C layer is able to mitigate the mechanical stress during lithiation of the Si thin film by buffering the volume changes and to reduce the loss of active lithium during solid electrolyte interphase formation and cycling.

Stable N-CuInSe.sub.2 /iodide-iodine photoelectrochemical cell

DOEpatents

Cahen, David; Chen, Yih W.

1985-01-01

In a photoelectrochemical solar cell, stable output and solar efficiency in excess of 10% are achieved with a photoanode of n-CuInSe.sub.2 electrode material and an iodine/iodide redox couple used in a liquid electrolyte. The photoanode is prepared by treating the electrode material by chemical etching, for example in Br.sub.2 /MeOH; heating the etched electrode material in air or oxygen; depositing a surface film coating of indium on the electrode material after the initial heating; and thereafter again heating the electrode material in air or oxygen to oxidize the indium. The electrolyte is treated by the addition of Cu.sup.+ or Cu.sup.2+ salts and In.sup.3+ salts.

Stable n-CuInSe/sub 2/iodide-iodine photoelectrochemical cell

DOEpatents

Cahen, D.; Chen, Y.W.

1984-09-20

In a photoelectrochemical solar cell, stable output and solar efficiency in excess of 10% are achieved with a photoanode of n-CuInSe/sub 2/ electrode material and an iodine/iodide redox couple used in a liquid electrolyte. The photoanode is prepared by treating the electrode material by chemical etching, for example in Br/sub 2//MeOH; heating the etched electrode material in air or oxygen; depositing a surface film coating of indium on the electrode material after the initial heating; and thereafter again heating the electrode material in air or oxygen to oxidize the indium. The electrolyte is treated by the addition of Cu/sup +/ or Cu/sup 2 +/ salts and in In/sup 3 +/ salts.

Voltammetric analysis apparatus and method

DOEpatents

Almon, A.C.

1993-06-08

An apparatus and method is described for electrochemical analysis of elements in solution. An auxiliary electrode, a reference electrode, and five working electrodes are positioned in a container containing a sample solution. The working electrodes are spaced apart evenly from each other and the auxiliary electrode to minimize any inter-electrode interference that may occur during analysis. An electric potential is applied between the auxiliary electrode and each of the working electrodes. Simultaneous measurements taken of the current flow through each of the working electrodes for each given potential in a potential range are used for identifying chemical elements present in the sample solution and their respective concentrations. Multiple working electrodes enable a more positive identification to be made by providing unique data characteristic of chemical elements present in the sample solution.

Recent progress in hollow sphere-based electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhao, Yan; Chen, Min; Wu, Limin

2016-08-01

Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

Recent progress in hollow sphere-based electrodes for high-performance supercapacitors.

PubMed

Zhao, Yan; Chen, Min; Wu, Limin

2016-08-26

Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

Electrospray ion source with reduced analyte electrochemistry

DOEpatents

Kertesz, Vilmos [Knoxville, TN; Van Berkel, Gary [Clinton, TN

2011-08-23

An electrospray ion (ESI) source and method capable of ionizing an analyte molecule without oxidizing or reducing the analyte of interest. The ESI source can include an emitter having a liquid conduit, a working electrode having a liquid contacting surface, a spray tip, a secondary working electrode, and a charge storage coating covering partially or fully the liquid contacting surface of the working electrode. The liquid conduit, the working electrode and the secondary working electrode can be in liquid communication. The electrospray ion source can also include a counter electrode proximate to, but separated from, said spray tip. The electrospray ion source can also include a power system for applying a voltage difference between the working electrodes and a counter-electrode. The power system can deliver pulsed voltage changes to the working electrodes during operation of said electrospray ion source to minimize the surface potential of the charge storage coating.

Electrospray ion source with reduced analyte electrochemistry

DOEpatents

Kertesz, Vilmos; Van Berkel, Gary J

2013-07-30

An electrospray ion (ESI) source and method capable of ionizing an analyte molecule without oxidizing or reducing the analyte of interest. The ESI source can include an emitter having a liquid conduit, a working electrode having a liquid contacting surface, a spray tip, a secondary working electrode, and a charge storage coating covering partially or fully the liquid contacting surface of the working electrode. The liquid conduit, the working electrode and the secondary working electrode can be in liquid communication. The electrospray ion source can also include a counter electrode proximate to, but separated from, said spray tip. The electrospray ion source can also include a power system for applying a voltage difference between the working electrodes and a counter-electrode. The power system can deliver pulsed voltage changes to the working electrodes during operation of said electrospray ion source to minimize the surface potential of the charge storage coating.

Hydrogen evolution reaction catalyst

DOEpatents

Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

2016-02-09

Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

Polarization study on doped lanthanum gallate electrolyte using impedance spectroscopy

NASA Astrophysics Data System (ADS)

Gong, Wenquan; Gopalan, Srikanth; Pal, Uday B.

2004-06-01

Alternating current complex impedance spectroscopy studies were conducted on symmetrical cells of the type [gas, electrode/La1-x Sr x Ga1-y Mg y O3 (LSGM) electrolyte/electrode, gas]. The electrode materials were slurry-coated on both sides of the LSGM electrolyte support. The electrodes selected for this investigation are candidate materials for solid oxide fuel cell (SOFC) electrodes. Cathode materials include La1-x Sr x MnO3 (LSM), La1-x Sr x Co y Fe1-y O3 (LSCF), a two-phase particulate composite consisting of LSM and doped-lanthanum gallate (LSGM), and LSCF + LSGM. Pt metal electrodes were also used for the purpose of comparison. Anode material investigated was the Ni + Ce0.85Gd0.15O2 composite. The study revealed important details pertaining to the charge-transfer reactions that occur in such electrodes. The information obtained can be used to design electrodes for intermediate temperature SOFCs based on LSGM electrolytes.

Neutron scattering study on cathode LiMn2O4 and solid electrolyte 5(Li2O)(P2O5)

NASA Astrophysics Data System (ADS)

Kartini, E.; Putra, Teguh P.; Jahya, A. K.; Insani, A.; Adams, S.

2014-09-01

Neutron scattering is very important technique in order to investigate the energy storage materials such as lithium-ion battery. The unique advantages, neutron can see the light atoms such as Hydrogen, Lithium, and Oxygen, where those elements are negligible by other corresponding X-ray method. On the other hand, the energy storage materials, such as lithium ion battery is very important for the application in the electric vehicles, electronic devices or home appliances. The battery contains electrodes (anode and cathode), and the electrolyte materials. There are many challenging to improve the existing lithium ion battery materials, in order to increase their life time, cyclic ability and also its stability. One of the most scientific challenging is to investigate the crystal structure of both electrode and electrolyte, such as cathodes LiCoO2, LiMn2O4 and LiFePO4, and solid electrolyte Li3PO4. Since all those battery materials contain Lithium ions and Oxygen, the used of neutron scattering techniques to study their structure and related properties are very important and indispensable. This article will review some works of investigating electrodes and electrolytes, LiMn2O4 and 5(Li2O)(P2O5), by using a high resolution powder diffraction (HRPD) at the multipurpose research reactor, RSG-Sywabessy of the National Nuclear Energy Agency (BATAN), Indonesia.

Tunnel structured manganese oxide nanowires as redox active electrodes for hybrid capacitive deionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byles, Bryan W.; Cullen, David A.; More, Karren Leslie

We report that hybrid capacitive deionization (HCDI), which combines a capacitive carbon electrode and a redox active electrode in a single device, has emerged as a promising method for water desalination, enabling higher ion removal capacity than devices containing two carbon electrodes. However, to date, the desalination performance of few redox active materials has been reported. For the first time, we present the electrochemical behavior of manganese oxide nanowires with four different tunnel crystal structures as faradaic electrodes in HCDI cells. Two of these phases are square tunnel structured manganese oxides, α-MnO 2 and todorokite-MnO 2. The other two phasesmore » have novel structures that cross-sectional scanning transmission electron microscopy analysis revealed to have ordered and disordered combinations of structural tunnels with different dimensions. The ion removal performance of the nanowires was evaluated not only in NaCl solution, which is traditionally used in laboratory experiments, but also in KCl and MgCl 2 solutions, providing better understanding of the behavior of these materials for desalination of brackish water that contains multiple cation species. High ion removal capacities (as large as 27.8 mg g -1, 44.4 mg g -1, and 43.1 mg g -1 in NaCl, KCl, and MgCl 2 solutions, respectively) and high ion removal rates (as large as 0.112 mg g -1 s -1, 0.165 mg g -1 s -1, and 0.164 mg g -1 s -1 in NaCl, KCl, and MgCl 2 solutions, respectively) were achieved. By comparing ion removal capacity to structural tunnel size, it was found that smaller tunnels do not favor the removal of cations with larger hydrated radii, and more efficient removal of larger hydrated cations can be achieved by utilizing manganese oxides with larger structural tunnels. Extended HCDI cycling and ex situ X-ray diffraction analysis revealed the excellent stability of the manganese oxide electrodes in repeated ion removal/ion release cycles, and compositional analysis of the electrodes indicated that ion removal is achieved through both surface redox reactions and intercalation of ions into the structural tunnels. In conclusion, this work contributes to the understanding of the behavior of faradaic materials in electrochemical water desalination and elucidates the relationship between the electrode material crystal structure and the ion removal capacity/ion removal rate in various salt solutions.« less

Tunnel structured manganese oxide nanowires as redox active electrodes for hybrid capacitive deionization

DOE PAGES

Byles, Bryan W.; Cullen, David A.; More, Karren Leslie; ...

2017-12-18

We report that hybrid capacitive deionization (HCDI), which combines a capacitive carbon electrode and a redox active electrode in a single device, has emerged as a promising method for water desalination, enabling higher ion removal capacity than devices containing two carbon electrodes. However, to date, the desalination performance of few redox active materials has been reported. For the first time, we present the electrochemical behavior of manganese oxide nanowires with four different tunnel crystal structures as faradaic electrodes in HCDI cells. Two of these phases are square tunnel structured manganese oxides, α-MnO 2 and todorokite-MnO 2. The other two phasesmore » have novel structures that cross-sectional scanning transmission electron microscopy analysis revealed to have ordered and disordered combinations of structural tunnels with different dimensions. The ion removal performance of the nanowires was evaluated not only in NaCl solution, which is traditionally used in laboratory experiments, but also in KCl and MgCl 2 solutions, providing better understanding of the behavior of these materials for desalination of brackish water that contains multiple cation species. High ion removal capacities (as large as 27.8 mg g -1, 44.4 mg g -1, and 43.1 mg g -1 in NaCl, KCl, and MgCl 2 solutions, respectively) and high ion removal rates (as large as 0.112 mg g -1 s -1, 0.165 mg g -1 s -1, and 0.164 mg g -1 s -1 in NaCl, KCl, and MgCl 2 solutions, respectively) were achieved. By comparing ion removal capacity to structural tunnel size, it was found that smaller tunnels do not favor the removal of cations with larger hydrated radii, and more efficient removal of larger hydrated cations can be achieved by utilizing manganese oxides with larger structural tunnels. Extended HCDI cycling and ex situ X-ray diffraction analysis revealed the excellent stability of the manganese oxide electrodes in repeated ion removal/ion release cycles, and compositional analysis of the electrodes indicated that ion removal is achieved through both surface redox reactions and intercalation of ions into the structural tunnels. In conclusion, this work contributes to the understanding of the behavior of faradaic materials in electrochemical water desalination and elucidates the relationship between the electrode material crystal structure and the ion removal capacity/ion removal rate in various salt solutions.« less

Perylene-Based All-Organic Redox Battery with Excellent Cycling Stability.

PubMed

Iordache, Adriana; Delhorbe, Virginie; Bardet, Michel; Dubois, Lionel; Gutel, Thibaut; Picard, Lionel

2016-09-07

Organic materials derived from biomass can constitute a viable option as replacements for inorganic materials in lithium-ion battery electrodes owing to their low production costs, recyclability, and structural diversity. Among them, conjugated carbonyls have become the most promising type of organic electrode material as they present high theoretical capacity, fast reaction kinetics, and quasi-infinite structural diversity. In this letter, we report a new perylene-based all-organic redox battery comprising two aromatic conjugated carbonyl electrode materials, the prelithiated tetra-lithium perylene-3,4,9,10-tetracarboxylate (PTCLi6) as negative electrode material and the poly(N-n-hexyl-3,4,9,10-perylene tetracarboxylic)imide (PTCI) as positive electrode material. The resulting battery shows promising long-term cycling stability up to 200 cycles. In view of the enhanced cycling performances, the two organic materials studied herein are proposed as suitable candidates for the development of new all-organic lithium-ion batteries.

Kerr electro-optic field mapping study of the effect of charge injection on the impulse breakdown strength of transformer oil

NASA Astrophysics Data System (ADS)

Zhang, X.; Zahn, M.

2013-10-01

The smart use of charge injection to improve breakdown strength in transformer oil is demonstrated in this paper. Hypothetically, bipolar homo-charge injection with reduced electric field at both electrodes may allow higher voltage operation without insulation failure, since electrical breakdown usually initiates at the electrode-dielectric interfaces. To find experimental evidence, the applicability and limitation of the hypothesis is first analyzed. Impulse breakdown tests and Kerr electro-optic field mapping measurements are then conducted with different combinations of parallel-plate aluminum and brass electrodes stressed by millisecond duration impulse. It is found that the breakdown voltage of brass anode and aluminum cathode is ˜50% higher than that of aluminum anode and brass cathode. This can be explained by charge injection patterns from Kerr measurements under a lower voltage, where aluminum and brass electrodes inject negative and positive charges, respectively. This work provides a feasible approach to investigating the effect of electrode material on breakdown strength.

Characterization of screen-printed electrodes for dielectric elastomer (DE) membranes: influence of screen dimensions and electrode thickness on actuator performance

NASA Astrophysics Data System (ADS)

Fasolt, Bettina; Hodgins, Micah; Seelecke, Stefan

2016-04-01

Screen printing is used as a method for printing electrodes on silicone thin films for the fabrication of dielectric elastomer transducers (DET). This method can be used to manufacture a multitude of patternable designs for actuator and sensor applications, implementing the same method for prototyping as well as large-scale production. The fabrication of DETs does not only require the development of a flexible, highly conductive electrode material, which adheres to a stretched and unstretched silicone film, but also calls for a thorough understanding of the effects of the different printing parameters. This work studies the influence of screen dimensions (open area, mesh thickness) as well as the influence of multiple-layer- printing on the electrode stiffness, electrical resistance and capacitance as well as actuator performance. The investigation was conducted in a custom-built testing device, which enabled an electro-mechanical characterization of the DET, simultaneously measuring parameters such as strain, voltage, current, force, sheet resistance, capacitance and membrane thickness. Magnified pictures of the electrodes will additionally illustrate the effects of the different printing parameters.

Porous WO3/graphene/polyester textile electrode materials with enhanced electrochemical performance for flexible solid-state supercapacitors.

PubMed

Jin, Li-Na; Liu, Ping; Jin, Chun; Zhang, Jia-Nan; Bian, Shao-Wei

2018-01-15

In this work, a flexible and porous WO 3 /grapheme/polyester (WO 3 /G/PT) textile electrode was successfully prepared by in situ growing WO 3 on the fiber surface inside G/PT composite fabrics. The unique electrode structure facilitates to enhance the energy storage performance because the 3D conductive network constructed by the G/PT increase the electron transportation rate, nanotructured WO 3 exposed enhanced electrochemically active surface area and the hierarchically porous structure improved the electrolyte ion diffusion rate. The optimized WO 3 /G/PT textile electrode exhibited good electrochemical performance with a high areal capacitance of 308.2mFcm -2 at a scan rate of 2mVs -1 and excellent cycling stability. A flexible asymmetric supercapacitor (ASC) device was further fabricated by using the WO 3 /G/PT electrode and G/PT electrode, which exhibited a good specific capacitance of 167.6mFcm -3 and high energy density of 60μWhcm -3 at the power density of 2320 μWcm -3 . Copyright © 2017 Elsevier Inc. All rights reserved.

Monolithic quasi-solid-state dye-sensitized solar cells based on graphene modified mesoscopic carbon counter electrodes

NASA Astrophysics Data System (ADS)

Rong, Yaoguang; Li, Xiong; Liu, Guanghui; Wang, Heng; Ku, Zhiliang; Xu, Mi; Liu, Linfeng; Hu, Min; Yang, Ying; Han, Hongwei

2013-03-01

We have developed a monolithic quasi-solid-state dye-sensitized solar cell (DSSC) based on graphene modified mesoscopic carbon counter electrode (GC-CE), which offers a promising prospect for commercial applications. Based on the design of a triple layer structure, the TiO2 working electrode layer, ZrO2 spacer layer and carbon counter electrode (CE) layer are constructed on a single conducting glass substrate by screen-printing. The quasi-solid-state polymer gel electrolyte employs a polymer composite as the gelator and could effectively infiltrate into the porous layers. Fabricated with normal carbon counter electrode (NC-CE) containing graphite and carbon black, the device shows a power conversion efficiency (PCE) of 5.09% with the fill factor (FF) of 0.63 at 100 mW cm-2 AM1.5 illumination. When the NC-CE is modified with graphene sheets, the PCE and FF could be enhanced to 6.27% and 0.71, respectively. This improvement indicates excellent conductivity and high electrocatalytic activity of the graphene sheets, which have been considered as a promising platinum-free electrode material for DSSCs.

Enabling aqueous processing for crack-free thick electrodes

DOE PAGES

Du, Zhijia; Rollag, K. M.; Li, J.; ...

2017-04-14

Aqueous processing of thick electrodes for Li-ion cells promises to increase energy density due to increased volume fraction of active materials, and to reduce cost due to the elimination of the toxic solvents. Here in this paper this work reports the processing and characterization of aqueous processed electrodes with high areal loading and associated full pouch cell performance. Cracking of the electrode coatings becomes a critical issue for aqueous processing of the positive electrode as areal loading increases above 20–25 mg/cm 2 (~4 mAh/cm 2). Crack initiation and propagation, which was observed during drying via optical microscopy, is related tomore » the build-up of capillary pressure during the drying process. The surface tension of water was reduced by the addition of isopropyl alcohol (IPA), which led to improved wettability and decreased capillary pressure during drying. The critical thickness (areal loading) without cracking increased gradually with increasing IPA content. The electrochemical performance was evaluated in pouch cells. Electrodes processed with water/IPA (80/20 wt%) mixture exhibited good structural integrity with good rate performance and cycling performance.« less

Electroreduction of Er 3+ in nonaqueous solvents

DOE PAGES

Small, Leo J.; Sears, Jeremiah M.; Lambert, Timothy N.; ...

2016-09-15

Here, the electroreduction of Er 3+ in propylene carbonate, N,N-dimethylformamide, or a variety of quaternary ammonium ionic liquids (ILs) was investigated using [Er(OTf) 3] and [Er(NTf 2) 3]. Systematic variation of the ILs' cation and anion, Er 3+ salt, and electrode material revealed a disparity in electrochemical interactions not previously seen. For most ILs at a platinum electrode, cyclic voltammetry exhibits irreversible interactions between Er 3+ salts and the electrode at potentials significantly less than the theoretical reduction potential for Er 3+. Throughout all solvent–salt systems tested, a deposit could be formed on the electrode, though obtaining a high purity,more » crystalline Er 0 deposit is challenging due to the extreme reactivity of the deposit and resulting chemical interactions, often resulting in the formation of a complex, amorphous solid–electrolyte interface that slowed deposition rates. Comparison of platinum, gold, nickel, and glassy carbon (GC) working electrodes revealed oxidation processes unique to the platinum surface. While no appreciable reduction current was observed on GC at the potentials investigated, deposits were seen on platinum, gold, and nickel electrodes.« less

Biosensing with Paper-Based Miniaturized Printed Electrodes-A Modern Trend.

PubMed

Silveira, Célia M; Monteiro, Tiago; Almeida, Maria Gabriela

2016-09-28

From the bench-mark work on microfluidics from the Whitesides's group in 2007, paper technology has experienced significant growth, particularly regarding applications in biomedical research and clinical diagnostics. Besides the structural properties supporting microfluidics, other advantageous features of paper materials, including their versatility, disposability and low cost, show off the great potential for the development of advanced and eco-friendly analytical tools. Consequently, paper was quickly employed in the field of electrochemical sensors, being an ideal material for producing custom, tailored and miniaturized devices. Stencil-, inkjet-, or screen-printing are the preferential techniques for electrode manufacturing. Not surprisingly, we witnessed a rapid increase in the number of publications on paper based screen-printed sensors at the turn of the past decade. Among the sensing strategies, various biosensors, coupling electrochemical detectors with biomolecules, have been proposed. This work provides a critical review and a discussion on the future progress of paper technology in the context of miniaturized printed electrochemical biosensors.

Lightweight fibrous nickel electrodes for nickel-hydrogen batteries

NASA Technical Reports Server (NTRS)

Britton, Doris L.

1989-01-01

The NASA Lewis Research Center is currently developing nickel electrodes for nickel-hydrogen batteries. These electrodes are lighter in weight and have higher energy densities than the heavier state-of-the-art sintered nickel electrodes. Lightweight fibrous materials or plaques are used as conductive supports for the nickel hydroxide active material. These materials are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. Evaluation is performed in half cells structured in the bipolar configuration. Initial performance tests include capacity measurements at five discharge levels, C/2, 1.0C, 1.37C, 2.0C, and 2.74C. The electrodes that pass the initial tests are life cycle-tested in a low Earth orbit regime at 80 percent depth of discharge.

Treating of solid earthen material and a method for measuring moisture content and resistivity of solid earthen material

DOEpatents

Heath, William; Richardson, Richard; Goheen, Steven

1994-01-01

The present invention includes a method of treating solid earthen material having volatile, semi-volatile and non-volatile contaminants. Six electrodes are inserted into a region of earthen material to be treated in a substantially equilateral hexagonal arrangement. Six phases of voltages are applied to corresponding electrodes. The voltages are adjusted within a first range of voltages to create multiple current paths between pairs of the electrodes. The current paths are evenly distributed throughout the region defined by the electrodes and therefore uniformly heat the region. The region of earthen material is heated to a temperature sufficient to substantially remove volatile and semi-volatile contaminants. This temperature is less than a melting temperature of the earthen material. The voltages are then increased to a second range of voltages effective to create dry regions around the electrodes. The dry regions have a perimeter which define a boundary between the dry regions and the earthen material exterior to the dry regions. Corona discharge occurs at the boundaries of the dry regions. As voltages are increased further, the dry regions move radially outward from the electrodes through the entire region. The corona boundaries decompose the non-volatilized contaminants remaining in the region. The hexagonal arrangement of electrodes is also preferable for measuring resistivity and moisture content of the earthen material. The electric field created between the electrodes is readily discernable and therefore facilitates accurate measurements.

Structure and Modification of Electrode Materials for Protein Electrochemistry.

PubMed

Jeuken, Lars J C

The interactions between proteins and electrode surfaces are of fundamental importance in bioelectrochemistry, including photobioelectrochemistry. In order to optimise the interaction between electrode and redox protein, either the electrode or the protein can be engineered, with the former being the most adopted approach. This tutorial review provides a basic description of the most commonly used electrode materials in bioelectrochemistry and discusses approaches to modify these surfaces. Carbon, gold and transparent electrodes (e.g. indium tin oxide) are covered, while approaches to form meso- and macroporous structured electrodes are also described. Electrode modifications include the chemical modification with (self-assembled) monolayers and the use of conducting polymers in which the protein is imbedded. The proteins themselves can either be in solution, electrostatically adsorbed on the surface or covalently bound to the electrode. Drawbacks and benefits of each material and its modifications are discussed. Where examples exist of applications in photobioelectrochemistry, these are highlighted.

Negative electrodes for Na-ion batteries.

PubMed

Dahbi, Mouad; Yabuuchi, Naoaki; Kubota, Kei; Tokiwa, Kazuyasu; Komaba, Shinichi

2014-08-07

Research interest in Na-ion batteries has increased rapidly because of the environmental friendliness of sodium compared to lithium. Throughout this Perspective paper, we report and review recent scientific advances in the field of negative electrode materials used for Na-ion batteries. This paper sheds light on negative electrode materials for Na-ion batteries: carbonaceous materials, oxides/phosphates (as sodium insertion materials), sodium alloy/compounds and so on. These electrode materials have different reaction mechanisms for electrochemical sodiation/desodiation processes. Moreover, not only sodiation-active materials but also binders, current collectors, electrolytes and electrode/electrolyte interphase and its stabilization are essential for long cycle life Na-ion batteries. This paper also addresses the prospect of Na-ion batteries as low-cost and long-life batteries with relatively high-energy density as their potential competitive edge over the commercialized Li-ion batteries.

Electro-active device using radial electric field piezo-diaphragm for sonic applications

NASA Technical Reports Server (NTRS)

Bryant, Robert G. (Inventor); Fox, Robert L. (Inventor)

2005-01-01

An electro-active transducer for sonic applications includes a ferroelectric material sandwiched by first and second electrode patterns to form a piezo-diaphragm coupled to a mounting frame. When the device is used as a sonic actuator, the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when voltage is applied to the electrode patterns. When the device is used as a sonic sensor, the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when the ferroelectric material experiences deflection in a direction substantially perpendicular thereto. In each case, the electrode patterns are designed to cause the electric field to: i) originate at a region of the ferroelectric material between the first and second electrode patterns, and ii) extend radially outward from the region of the ferroelectric material (at which the electric field originates) and substantially parallel to the plane of the ferroelectric material. The mounting frame perimetrically surrounds the peizo-diaphragm and enables attachment of the piezo-diaphragm to a housing.

Facile hydrothermal synthesis of one-dimensional nanostructured α-MnO2 for supercapacitors

NASA Astrophysics Data System (ADS)

Wei, Hongmei; Wang, Jinxing; Yang, Shengwei; Zhang, Yangyang; Li, Tengfei; Zhao, Shuoqing

2016-09-01

α-MnO2 recently becomes a promising candidate of electrode materials for high effective supercapacitors in which it possesses of unique structure of 2×2 tunnels that can provide more electrons and ions diffusion paths. In this work, different morphologies MnO2 with α-phase crystalline structure have been prepared via a one-step facile hydrothermal method by adding various reagents. Compositions, microstructures and morphologies of these as-synthesized materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and electrochemical properties of α-MnO2 electrodes were studied by the cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) in 1 M Na2SO4 aqueous solution. The specific capacitance of nanowires were 158 F g-1 while the specific capacitance of nanorods were 106 F g-1 at current density of 4 A g-1, and improved performance of the wire-like electrode material was probably ascribed to the larger specific surface area that can provide relatively more active sites for high capacity. Meanwhile, both the nanowires and nanorods of MnO2 presented fine cycle stability after continuous multiple charge/discharge times.

Facile Synthesis of Flowerlike LiFe5O8 Microspheres for Electrochemical Supercapacitors.

PubMed

Lin, Ying; Dong, Jingjing; Dai, Jingjing; Wang, Jingping; Yang, Haibo; Zong, Hanwen

2017-12-18

Facile synthesis of porous and hollow spinel materials is very urgent due to their extensive applications in the field of energy storage. In present work, flowerlike porous LiFe 5 O 8 microspheres etched for 15, 30, and 45 min (named as p-LFO-15, p-LFO-30, and p-LFO-45, respectively) are successfully synthesized through a facile chemical etching method based on bulk LiFe 5 O 8 (LFO) particles as precursors, and they are applied as electrode materials for high-performance electrochemical capacitors. In particular, the specific surface area of p-LFO-45 reaches 46.13 m 2 g -1 , which is 112 times greater than that of the unetched counterpart. Therefore, the p-LFO-45 electrode can achieve a higher capacitance of 278 F g -1 at a scan rate of 5 mV s -1 than the unetched counterpart. Furthermore, the p-LFO-45 electrode presents a good cycling stability with 78.3% of capacitive retention after 2000 cycles, which is much higher than that of the unetched LFO particles (66%). Therefore, the flowerlike porous LFO microspheres are very promising candidate materials for supercapacitor applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Gui -Liang; Sheng, Tian; Chong, Lina

Sodium-ion batteries (SIBs) have been considered as one of the promising power source candidates for the stationary storage industries owing to the much lower cost of sodium than lithium. It is well-known that the electrode materials largely determine the energy density of the battery systems. However, recent discoveries on the electrode materials showed that most of them present distinct lithium and sodium storage performance, which is not yet well understood. In this work, we performed a comparative understanding on the structural changes of porous cobalt oxide during its electrochemical lithiation and sodiation process by in operando synchrotron small angel X-raymore » scattering, X-ray diffraction, and X-ray absorption spectroscopy. It was found that compared to the lithiation process, the porous cobalt oxide undergoes less pore structure changes, oxidation state, and local structure changes as well as crystal structure evolution during its sodiation process, which is attributed to the intrinsic low sodiation activity of cobalt oxide as evidenced by ab initio molecular dynamics simulations. Moreover, it was indicated that the sodiation activity of metal sulfides is higher than that of metal oxides, indicating a better candidate for SIBs. Furthermore, such understanding is crucial for future design and improvement of high-performance electrode materials for SIBs.« less

A novel carbon electrode material for highly improved EDLC performance.

PubMed

Fang, Baizeng; Binder, Leo

2006-04-20

Porous materials, developed by grafting functional groups through chemical surface modification with a surfactant, represent an innovative concept in energy storage. This work reports, in detail, the first practical realization of a novel carbon electrode based on grafting of vinyltrimethoxysilane (vtmos) functional group for energy storage in electric double layer capacitor (EDLC). Surface modification with surfactant vtmos enhances the hydrophobisation of activated carbon and the affinity toward propylene carbonate (PC) solvent, which improves the wettability of activated carbon in the electrolyte solution based on PC solvent, resulting in not only a lower resistance to the transport of electrolyte ions within micropores of activated carbon but also more usable surface area for the formation of electric double layer, and accordingly, higher specific capacitance, energy density, and power capability available from the capacitor based on modified carbon. Especially, the effects from surface modification become superior at higher discharge rate, at which much better EDLC performance (i.e., much higher energy density and power capability) has been achieved by the modified carbon, suggesting that the modified carbon is a novel and very promising electrode material of EDLC for large current applications where both high energy density and power capability are required.

Flexible 3D porous CuO nanowire arrays for enzymeless glucose sensing: in situ engineered versus ex situ piled

NASA Astrophysics Data System (ADS)

Huang, Jianfei; Zhu, Yihua; Yang, Xiaoling; Chen, Wei; Zhou, Ying; Li, Chunzhong

2014-12-01

Convenient determination of glucose in a sensitive, reliable and cost-effective way has aroused sustained research passion, bringing along assiduous investigation of high-performance electroactive nanomaterials to build enzymeless sensors. In addition to the intrinsic electrocatalytic capability of the sensing materials, electrode architecture at the microscale is also crucial for fully enhancing the performance. In this work, free-standing porous CuO nanowire (NW) was taken as a model sensing material to illustrate this point, where an in situ formed 3D CuO nanowire array (NWA) and CuO nanowires pile (NWP) immobilized with polymer binder by conventional drop-casting technique were both studied for enzymeless glucose sensing. The NWA electrode exhibited greatly promoted electrochemistry characterized by decreased overpotential for electro-oxidation of glucose and over 5-fold higher sensitivity compared to the NWP counterpart, benefiting from the binder-free nanoarray structure. Besides, its sensing performance was also satisfying in terms of rapidness, selectivity and durability. Further, the CuO NWA was utilized to fabricate a flexible sensor which showed excellent performance stability against mechanical bending. Thanks to its favorable electrode architecture, the CuO NWA is believed to offer opportunities for building high-efficiency flexible electrochemical devices.Convenient determination of glucose in a sensitive, reliable and cost-effective way has aroused sustained research passion, bringing along assiduous investigation of high-performance electroactive nanomaterials to build enzymeless sensors. In addition to the intrinsic electrocatalytic capability of the sensing materials, electrode architecture at the microscale is also crucial for fully enhancing the performance. In this work, free-standing porous CuO nanowire (NW) was taken as a model sensing material to illustrate this point, where an in situ formed 3D CuO nanowire array (NWA) and CuO nanowires pile (NWP) immobilized with polymer binder by conventional drop-casting technique were both studied for enzymeless glucose sensing. The NWA electrode exhibited greatly promoted electrochemistry characterized by decreased overpotential for electro-oxidation of glucose and over 5-fold higher sensitivity compared to the NWP counterpart, benefiting from the binder-free nanoarray structure. Besides, its sensing performance was also satisfying in terms of rapidness, selectivity and durability. Further, the CuO NWA was utilized to fabricate a flexible sensor which showed excellent performance stability against mechanical bending. Thanks to its favorable electrode architecture, the CuO NWA is believed to offer opportunities for building high-efficiency flexible electrochemical devices. Electronic supplementary information (ESI) available: TEM images of CuO nanowires. SEM images of the composite film of CuO NWs in the Nafion binder. Flowchart of electrodes fabrication procedures. Current response time to addition of the glucose. Amperometric i-t test for the NWP under +0.35 V. Nyquist plot of the electrodes. SEM images of fractured parts of CuO nanowires at the NWP-Nafion film. Parameter comparison of enzymeless sensors for glucose detection. See DOI: 10.1039/c4nr05620e

Dual-protection of a graphene-sulfur composite by a compact graphene skin and an atomic layer deposited oxide coating for a lithium-sulfur battery

NASA Astrophysics Data System (ADS)

Yu, Mingpeng; Wang, Aiji; Tian, Fuyang; Song, Hongquan; Wang, Yinshu; Li, Chun; Hong, Jong-Dal; Shi, Gaoquan

2015-03-01

A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g-1 at a current density of 0.2 C. A high capacity of 846 mA h g-1 was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g-1 and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%.A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g-1 at a current density of 0.2 C. A high capacity of 846 mA h g-1 was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g-1 and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%. Electronic supplementary information (ESI) available: Procedures of ALD operation, supplementary figures and details of theoretical simulations. See DOI: 10.1039/c5nr00166h

Micro supercapacitors based on a 3D structure with symmetric graphene or activated carbon electrodes

NASA Astrophysics Data System (ADS)

Li, Siwei; Wang, Xiaohong; Xing, Hexin; Shen, Caiwei

2013-11-01

This paper presents three-dimensional (3D) micro supercapacitors with thick interdigital electrodes supported and separated by SU-8. Nanoporous carbon materials including graphene and activated carbon (AC) are used as active materials in self-supporting composites to build the electrodes. The SU-8 separators provide mechanical support for thick electrodes and allow a considerable amount of material to be loaded in a limited footprint area. The prototypes have been accomplished by a simple microelectromechanical systems (MEMS) fabrication process and sealed by polydimethylsiloxane (PDMS) caps with ionic liquid electrolytes injected into the electrode area. Electrochemical tests demonstrate that the graphene-based prototype with 100 µm thick electrodes shows good power performance and provides a considerable specific capacitance of about 60 mF cm-2. Two AC-based prototypes show larger capacitance of 160 mF cm-2 and 311 mF cm-2 with 100 µm and 200 µm thick electrodes respectively, because of higher volume density of the material. The results demonstrate that both thick 3D electrode structure and volume capacitance of the electrode material are key factors for high-performance micro supercapacitors, which can be potentially used in specific applications such as power suppliers and storage components for harvesters.

Effect of Polymer Electrode Morphology on Performance of a Lithium/Polypyrrole Battery. M.S. Thesis

NASA Technical Reports Server (NTRS)

Nicholson, Marjorie Anne

1991-01-01

A variety of conducting polymer batteries were described in the recent literature. In this work, a Li/Polypyrrole secondary battery is described. The effect of controlling the morphology of the polymer on enhancement of counterion diffusion in the polymer phase is explored. A method of preparing conducting polymers was developed which yields high surface area per unit volume of electrode material. A porous membrane is used as a template in which to electrochemically polymerize pyrrole, then the membrane is dissolved, leaving the polymer in a fibrillar form. Conventionally, the polymer is electrochemically polymerized as a dense polymer film on a smooth Pt disk electrode. Previous work has shown that when the polymer is electrochemically polymerized in fribrillar form, charge transport rates are faster and charge capacities are greater than for dense, conventionally grown films containing the same amount of polymer. The purpose is to expand previous work by further investigating the possibilities of the optimization of transport rates in polypyrrole films by controlling the morphology of the films. The utility of fibrillar polypyrrole as a cathode material in a lithium/polymer secondary battery is then assessed. The performance of the fibrillar battery is compared to the performance of an analogous battery which employed a conventionally grown polypyrrole film. The study includes a comparison of cyclic voltammetry, shape of charge/discharge curves, discharge time and voltage, cycle life, coulombic efficiencies, charge capacities, energy densities, and energy efficiencies.

Soft actuator based on Kraton with GO/Ag/Pani composite electrodes for robotic applications

NASA Astrophysics Data System (ADS)

Khan, Ajahar; Kant Jain, Ravi; Banerjee, Priyabrata; Inamuddin; Asiri, Abdullah M.

2017-11-01

In this work, electrochemically-driven Kraton/graphene oxide/Ag/polyaniline (Kraton/GO/Ag/Pani) polymer composite based ionic polymer metal composite (IPMC) was fabricated as a soft actuator. Silver nanopowder with polyaniline coating used as an electrode material is a novel approach in the fabrication of IPMC, which gives new opportunities for development of the electrode on ionic polymer actuator surfaces directly without electroless plating of Pt or Au metal. The Kraton/GO/Ag/Pani membrane showed much higher water-uptake (WU), ion exchange capacity (IEC), proton conductivity than those of several reported IPMC membranes. The enhanced actuation performance indicates that the Kraton/GO/Ag/Pani is a better alternative to the highly expensive commercialized IPMC actuator.

Voltametric analysis apparatus and method

DOEpatents

Almon, Amy C.

1993-01-01

An apparatus and method for electrochemical analysis of elements in solution. An auxiliary electrode 14, a reference electrode 18, and five working electrodes 20, 22, 26, 28, and 30 are positioned in a container 12 containing a sample solution 34. The working electrodes are spaced apart evenly from each other and auxiliary electrode 14 to minimize any inter-electrode interference that may occur during analysis. An electric potential is applied between auxiliary electrode 14 and each of the working electrodes 20, 22, 26, 28, and 30. Simultaneous measurements taken of the current flow through each of the working electrodes for each given potential in a potential range are used for identifying chemical elements present in sample solution 34 and their respective concentrations. Multiple working electrodes enable a more positive identification to be made by providing unique data characteristic of chemical elements present in the sample solution.

Effects of Different Materials Used for Internal Floating Electrode on the Photovoltaic Properties of Tandem Type Organic Solar Cell

NASA Astrophysics Data System (ADS)

Triyana, Kuwat; Yasuda, Takeshi; Fujita, Katsuhiko; Tsutsui, Tetsuo

2004-04-01

Three thin heterojunctions sandwiched between indium tin oxide (ITO) and the top electrode as triple-heterojunction organic solar cells have been fabricated. Each heterojunction cell consists of CuPc as a donor layer and perilene tetracrboxylic-bis-benzimidazole (PTCBI) as an acceptor layer. Ultra thin (1 nm average thickness) layers of Ag or Au have been inserted between two heterojunctions as an internal electrode. Ag and Au were chosen as materials both for internal floating and top electrodes. Influences of different deposition sequences of the organic layer in each heterojunction cell and different electrode materials were also investigated. The optimum devices were obtained when the same material was used both as an internal electrode and a top electrode. When the deposition sequence of the heterojunction is PTCBI/CuPc, the most suitable electrode is Au and the ITO is negative relative to the top electrode. Meanwhile, Ag is suitable for an electrode when the deposition sequence is CuPc/PTCBI. In this second deposition sequence, the ITO is positive relative to the top electrode. The open circuit voltage (Voc) of both optimum devices is on the order of 1.35-1.5 V. These values are approximately three times higher than that in single-heterojunction organic solar cells.

Electroless-plated Ni pattern with catalyst printing on indium-gallium-zinc oxide surface

NASA Astrophysics Data System (ADS)

Onoue, Miki; Ogura, Shintaro; Kusaka, Yasuyuki; Fukuda, Nobuko; Yamamoto, Noritaka; Kojima, Keisuke; Chikama, Katsumi; Ushijima, Hirobumi

2017-05-01

Electroless plated metals have been used for wiring and electrodes in the manufacture of electronic devices. To obtain plated patterns, etching and photoresist are generally used. However, through catalyst patterning by printing, we can obtain metal patterns without etching and photoresists by electroless plating. Solution-processed indium-gallium-zinc oxide (IGZO) has received significant attention for showing high performance and ease of preparation in air atmosphere. In this study, we prepared an electroless plated pattern by catalyst printing as electrodes of IGZO TFT. There are few reports on the application of plated metal electrodes prepared by catalyst printing to the source and drain electrodes of IGZO TFT. The prepared IGZO TFT exhibits a typical current-voltage (I-V) curve. The plated electrodes caused many problems such as performance degradation. However, our result showed that the plated metal electrodes can drive IGZO TFT. In addition, we confirm plated metal growth into the catalyst layer by cross sectional scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS) of the plated Ni. We discuss the relevance of the measured work function (WF) of the electrode materials and the performance of IGZO TFT.

Au-modified three-dimensional In2O3 inverse opals: synthesis and improved performance for acetone sensing toward diagnosis of diabetes

NASA Astrophysics Data System (ADS)

Xing, Ruiqing; Li, Qingling; Xia, Lei; Song, Jian; Xu, Lin; Zhang, Jiahuan; Xie, Yi; Song, Hongwei

2015-07-01

Analyzing the volatile organic compounds (VOCs) in exhaled breath effectively is crucial to medical treatment, which can provide a fast and noninvasive way to diagnose disease. Well-designed materials with controlled structures have great influence on the sensing performance. In this work, the ordered three dimensional inverse opal (3DIO) macroporous In2O3 films with additional via-hole architectures were fabricated and different amounts of gold nanoparticles (Au NPs) were loaded on the In2O3 films aiming at enhancing their electrical responses. The gas sensing to acetone toward diabetes diagnosis in exhaled breath was performed with different Au/In2O3 electrodes. Representatively, the best 3DIO Au/In2O3 sensor can detect acetone effectively at 340 °C with response of 42.4 to 5 ppm, the actual detection limit is as low as 20 ppb, and it holds a dynamic response of 11 s and a good selectivity. Moreover, clinical tests proved that the as-prepared 3DIO Au/In2O3 IO sensor could distinguish acetone biomarkers in human breath clearly. The excellent gas sensing properties of the Au/In2O3 electrodes were attributed to the ``spillover effects'' between Au and In2O3 and the special 3DIO structure. This work indicates that 3DIO Au/In2O3 composite is a promising electrode material for actual application in the monitoring and detection of diabetes through exhaled breath.Analyzing the volatile organic compounds (VOCs) in exhaled breath effectively is crucial to medical treatment, which can provide a fast and noninvasive way to diagnose disease. Well-designed materials with controlled structures have great influence on the sensing performance. In this work, the ordered three dimensional inverse opal (3DIO) macroporous In2O3 films with additional via-hole architectures were fabricated and different amounts of gold nanoparticles (Au NPs) were loaded on the In2O3 films aiming at enhancing their electrical responses. The gas sensing to acetone toward diabetes diagnosis in exhaled breath was performed with different Au/In2O3 electrodes. Representatively, the best 3DIO Au/In2O3 sensor can detect acetone effectively at 340 °C with response of 42.4 to 5 ppm, the actual detection limit is as low as 20 ppb, and it holds a dynamic response of 11 s and a good selectivity. Moreover, clinical tests proved that the as-prepared 3DIO Au/In2O3 IO sensor could distinguish acetone biomarkers in human breath clearly. The excellent gas sensing properties of the Au/In2O3 electrodes were attributed to the ``spillover effects'' between Au and In2O3 and the special 3DIO structure. This work indicates that 3DIO Au/In2O3 composite is a promising electrode material for actual application in the monitoring and detection of diabetes through exhaled breath. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02709h

Electrical performance of PEDOT:PSS-based textile electrodes for wearable ECG monitoring: a comparative study.

PubMed

Castrillón, Reinel; Pérez, Jairo J; Andrade-Caicedo, Henry

2018-04-02

Wearable textile electrodes for the detection of biopotentials are a promising tool for the monitoring and early diagnosis of chronic diseases. We present a comparative study of the electrical characteristics of four textile electrodes manufactured from common fabrics treated with a conductive polymer, a commercial fabric, and disposable Ag/AgCl electrodes. These characteristics will allow identifying the performance of the materials when used as ECG electrodes. The electrodes were subjected to different electrical tests, and complemented with conductivity calculations and microscopic images to determine their feasibility in the detection of ECG signals. We evaluated four electrical characteristics: contact impedance, electrode polarization, noise, and long-term performance. We analyzed PEDOT:PSS treated fabrics based on cotton, cotton-polyester, lycra and polyester; also a commercial fabric made of silver-plated nylon Shielde® Med-Tex P130, and commercial Ag/AgCl electrodes. We calculated conductivity from the surface resistance and, analyzed their surface at a microscopic level. Rwizard was used in the statistical analysis. The results showed that textile electrodes treated with PEDOT:PSS are suitable for the detection of ECG signals. The error detecting features of the ECG signal was lower than 2% and the electrodes kept working properly after 36 h of continuous use. Even though the contact impedance and the polarization level in textile electrodes were greater than in commercial electrodes, these parameters did not affect the acquisition of the ECG signals. Fabrics conductivity calculations were consistent to the contact impedance.

Modified Gold Electrode and Hollow Mn3O4 Nanoparticles as Electrode Materials for Microbial Fuel Cell Applications

NASA Astrophysics Data System (ADS)

Dhungana, Pramod

Microbial fuel cell (MFC) technology has attracted great attention in the scientific community as it offers the possibility of extraction of electricity from wide range of soluble and dissolved organic waste or renewable biomass, including sludge, waste water and cellulosic biomass. Microbial fuel cells are devices that utilize microbial metabolic processes to convert chemical energy via the oxidation of organic substances to produce electric current. MFCs consist of two chambers, an anode and cathode, separated by ion-permeable materials. The efficiency of producing electricity using the MFC depends on several factors such as immobilization of microorganisms on anode, mode of electron transfer, types of substrate/fuel and effectiveness of cathode materials for oxygen reduction reaction (ORR). In this work, in order to immobilize the microorganisms on anode materials, we have investigated the surface modification of gold electrode (anode) using alkyl dithiol and aryl thiol with glucose. The modification processes were characterized by using contact angle measurements and proton nuclear magnetic resonance (NMR). In order to study the effectiveness of cathode materials for ORR, we have synthesized hollow Mn3O 4 nanoparticles which are electrically very poor. Therefore, the hollow nanoparticles were mixed with electrically conductive multi-walled carbon nanotube as support and optimized the mixing process. This composite material shows enhanced ORR activity in all types of pH conditions. In future, we will focus to integrate anode and cathode in MFC to check its efficiency to produce electricity.

Ultrahigh volumetric capacitance and cyclic stability of fluorine and nitrogen co-doped carbon microspheres

NASA Astrophysics Data System (ADS)

Zhou, Junshuang; Lian, Jie; Hou, Li; Zhang, Junchuan; Gou, Huiyang; Xia, Meirong; Zhao, Yufeng; Strobel, Timothy A.; Tao, Lu; Gao, Faming

2015-09-01

Highly porous nanostructures with large surface areas are typically employed for electrical double-layer capacitors to improve gravimetric energy storage capacity; however, high surface area carbon-based electrodes result in poor volumetric capacitance because of the low packing density of porous materials. Here, we demonstrate ultrahigh volumetric capacitance of 521 F cm-3 in aqueous electrolytes for non-porous carbon microsphere electrodes co-doped with fluorine and nitrogen synthesized by low-temperature solvothermal route, rivaling expensive RuO2 or MnO2 pseudo-capacitors. The new electrodes also exhibit excellent cyclic stability without capacitance loss after 10,000 cycles in both acidic and basic electrolytes at a high charge current of 5 A g-1. This work provides a new approach for designing high-performance electrodes with exceptional volumetric capacitance with high mass loadings and charge rates for long-lived electrochemical energy storage systems.

Porous CrN thin films by selectively etching CrCuN for symmetric supercapacitors

NASA Astrophysics Data System (ADS)

Wei, Binbin; Mei, Gui; Liang, Hanfeng; Qi, Zhengbing; Zhang, Dongfang; Shen, Hao; Wang, Zhoucheng

2018-05-01

Transition metal nitrides are regarded as a new class of excellent electrode materials for high-performance supercapacitors due to their superior chemical stability and excellent electrical conductivity. We synthesize successfully the porous CrN thin films for binder-free supercapacitor electrodes by reactive magnetron co-sputtering and selective chemical etching. The porous CrN thin film electrodes exhibit high-capacitance performance (31.3 mF cm-2 at 1.0 mA cm-2) and reasonable cycling stability (94% retention after 20000 cycles). Moreover, the specific capacitance is more than two-fold higher than that of the CrN thin film electrodes in previous work. In addition, a symmetric supercapacitor device with a maximum energy density of 14.4 mWh cm-3 and a maximum power density of 6.6 W cm-3 is achieved. These findings demonstrate that the porous CrN thin films will have potential applications in supercapacitors.

In situ prepared transparent polyaniline electrode and its application in bifacial dye-sensitized solar cells.

PubMed

Tai, Qidong; Chen, Bolei; Guo, Feng; Xu, Sheng; Hu, Hao; Sebo, Bobby; Zhao, Xing-Zhong

2011-05-24

Highly uniform and transparent polyaniline (PANI) electrodes that can be used as counter electrodes in dye-sensitized solar cells (DSSCs) were prepared by a facile in situ polymerization method. They were used to fabricate a novel bifacially active transparent DSSC, which showed conversion efficiencies of 6.54 and 4.26% corresponding to front- and rear-side illumination, respectively. Meanwhile, the efficiency of the same photoanode employing a Pt counter electrode was 6.69%. Compared to conventional Pt-based DSSCs, the design of the bifacial DSSC fabricated in this work would help to bring down the cost of energy production due to the lower cost of the materials and the higher power-generating efficiency of such devices for their capabilities of utilizing the light from both sides. These promising results highlight the potential application of PANI in cost-effective, transparent DSSCs.

High performance flexible pH sensor based on polyaniline nanopillar array electrode.

PubMed

Yoon, Jo Hee; Hong, Seok Bok; Yun, Seok-Oh; Lee, Seok Jae; Lee, Tae Jae; Lee, Kyoung G; Choi, Bong Gill

2017-03-15

Flexible pH sensor technologies have attracted a great deal of attention in many applications, such as, wearable health care devices and monitors for chemical and biological processes. Here, we fabricated flexible and thin pH sensors using a two electrode configuration comprised of a polyaniline nanopillar (PAN) array working electrode and an Ag/AgCl reference electrode. In order to provide nanostructure, soft lithography using a polymeric blend was employed to create a flexible nanopillar backbone film. Polyaniline-sensing materials were deposited on a patterned-nanopillar array by electrochemical deposition. The pH sensors produced exhibited a near-Nernstian response (∼60.3mV/pH), which was maintained in a bent state. In addition, pH sensors showed other excellent sensor performances in terms of response time, reversibility, repeatability, selectivity, and stability. Copyright © 2016 Elsevier Inc. All rights reserved.

Novel Signal-Amplified Fenitrothion Electrochemical Assay, Based on Glassy Carbon Electrode Modified with Dispersed Graphene Oxide

NASA Astrophysics Data System (ADS)

Wang, Limin; Dong, Jinbo; Wang, Yulong; Cheng, Qi; Yang, Mingming; Cai, Jia; Liu, Fengquan

2016-03-01

A novel signal-amplified electrochemical assay for the determination of fenitrothion was developed, based on the redox behaviour of organophosphorus pesticides on a glassy carbon working electrode. The electrode was modified using graphene oxide dispersion. The electrochemical response of fenitrothion at the modified electrode was investigated using cyclic voltammetry, current-time curves, and square-wave voltammetry. Experimental parameters, namely the accumulation conditions, pH value, and volume of dispersed material, were optimised. Under the optimum conditions, a good linear relationship was obtained between the oxidation peak current and the fenitrothion concentration. The linear range was 1-400 ng·mL-1, with a detection limit of 0.1 ng·mL-1 (signal-to-nose ratio = 3). The high sensitivity of the sensor was demonstrated by determining fenitrothion in pakchoi samples.

High Density Polymer-Based Integrated Electgrode Array

DOEpatents

Maghribi, Mariam N.; Krulevitch, Peter A.; Davidson, James Courtney; Hamilton, Julie K.

2006-04-25

A high density polymer-based integrated electrode apparatus that comprises a central electrode body and a multiplicity of arms extending from the electrode body. The central electrode body and the multiplicity of arms are comprised of a silicone material with metal features in said silicone material that comprise electronic circuits.

Designed Electroresponsive Biomaterials: Sequence-Controlled Behavior

DTIC Science & Technology

2010-06-29

protein of the M13 . Traditional phage and yeast display methodologies indicate that peptide sequences with high affinities for electrode materials...drug delivery. The original vision for this work was to employ combinatorial tools such as phage and yeast display under electrical selection pressure...and drug delivery. The original vision for this work was to employ combinatorial tools such as phage and yeast display under electrical selection

Making a commercial carbon fiber cloth having comparable capacitances to carbon nanotubes and graphene in supercapacitors through a "top-down" approach.

PubMed

Zhang, Tianchang; Kim, Christine H J; Cheng, Yingwen; Ma, Yanwen; Zhang, Hongbo; Liu, Jie

2015-02-21

A "top-down" and scalable approach for processing carbon fiber cloth (CFC) into flexible and all-carbon electrodes with remarkable areal capacity and cyclic stability was developed. CFC is commercially available in large quantities but its use as an electrode material in supercapacitors is not satisfactory. The approach demonstrated in this work is based on the sequential treatment of CFC with KOH activation and high temperature annealing that can effectively improve its specific surface area to a remarkable 2780 m(2) g(-1) while at the same time achieving a good electrical conductivity of 320 S m(-1) without sacrificing its intrinsic mechanical strength and flexibility. The processed CFC can be directly used as an electrode for supercapacitors without any binders, conductive additives and current collectors while avoiding elaborate electrode processing steps to deliver a specific capacitance of ∼0.5 F cm(-2) and ∼197 F g(-1) with remarkable rate performance and excellent cyclic stability. The properties of these processed CFCs are comparable or better than graphene and carbon nanotube based electrodes. We further demonstrate symmetric solid-state supercapacitors based on these processed CFCs with very good flexibility. This "top-down" and scalable approach can be readily applied to other types of commercially available carbon materials and therefore can have a substantial significance for high performance supercapacitor devices.

Ruthenium-based, inert oxide electrodes for impregnating active materials in nickel plaques

NASA Astrophysics Data System (ADS)

Manoharan, R.; Uma, M.

Titanium electrodes coated with mixed ruthenium-iridium-titanium oxides are tested as inert counter electrodes for impregnating active materials in porous nickel plaques. The latter are to be used as the positive electrodes in nickel/cadmium cells. Weight losses and variations in bath voltage have been monitored while using these electrodes in the impregnation bath. A 2.85 Ah nickel/cadmium cell has been constructed using nickel electrodes developed by employing the coated electrodes of this study. The performances of these coated electrodes are compared with those of platinum electrodes that are currently employed by nickel/cadmium battery manufacturers. The results are found to be satisfactory.

Actinide ion sensor for pyroprocess monitoring

DOEpatents

Jue, Jan-fong; Li, Shelly X.

2014-06-03

An apparatus for real-time, in-situ monitoring of actinide ion concentrations which comprises a working electrode, a reference electrode, a container, a working electrolyte, a separator, a reference electrolyte, and a voltmeter. The container holds the working electrolyte. The voltmeter is electrically connected to the working electrode and the reference electrode and measures the voltage between those electrodes. The working electrode contacts the working electrolyte. The working electrolyte comprises an actinide ion of interest. The reference electrode contacts the reference electrolyte. The reference electrolyte is separated from the working electrolyte by the separator. The separator contacts both the working electrolyte and the reference electrolyte. The separator is ionically conductive to the actinide ion of interest. The reference electrolyte comprises a known concentration of the actinide ion of interest. The separator comprises a beta double prime alumina exchanged with the actinide ion of interest.

Method of preparing electrodes with porous current collector structures and solid reactants for secondary electrochemical cells

DOEpatents

Gay, Eddie C.; Martino, Fredric J.

1976-01-01

Particulate electrode reactants, for instance transition metal sulfides for the positive electrodes and lithium alloys for the negative electrodes, are vibratorily compacted into porous, electrically conductive structures. Structures of high porosity support sufficient reactant material to provide high cell capacity per unit weight while serving as an electrical current collector to improve the utilization of reactant materials. Pore sizes of the structure and particle sizes of the reactant material are selected to permit uniform vibratory loading of the substrate without settling of the reactant material during cycling.

Electrode structures and surfaces for Li batteries

DOEpatents

Thackeray, Michael M.; Kang, Sun-Ho; Balasubramanian, Mahalingam; Croy, Jason

2017-03-14

This invention relates to methods of preparing positive electrode materials for electrochemical cells and batteries. It relates, in particular, to a method for fabricating lithium-metal-oxide electrode materials for lithium cells and batteries. The method comprises contacting a hydrogen-lithium-manganese-oxide material with one or more metal ions, preferably in an acidic solution, to insert the one or more metal ions into the hydrogen-lithium-manganese-oxide material; heat-treating the resulting product to form a powdered metal oxide composition; and forming an electrode from the powdered metal oxide composition.

Advanced 3D Ni(OH)2/CNT Gel Composite Electrodes for Supercapacitors

NASA Astrophysics Data System (ADS)

Cheng, Hanlin; Duong, Hai Minh

2015-03-01

In order to enhance the performance of supercapacitors, advanced 3D Porous CNT/Ni(OH)2 gel composite electrodes are developed in this work. Compared with previously reported graphene gel supercapacitors, our electrodes using 1D CNTs have smaller diffusion resistance due to a shorter ion transport path. The developed 3D xerogel composite electrodes demonstrate the success of a careful engineered guest/host materials interface. Initially, the CNT gels are coated on the nickel foam to form a 3D scaffold, which serves as a microscopic electrical conductive network. Then Ni(OH)2 are incorporated using a traditional electrodeposition method. In this work, two types of the 3D CNT-coated nickel foams are investigated. The gels can be used directly as hydrogels or dried in air to form xerogels. Both hydrogels and xerogels present 3D tangled CNT networks. It shows that the hydrogel composite electrodes with unbundled CNTs, though presenting high capacitances of 1400 F/g at low discharge rate, possess lower capacitances at higher discharge rate and a poor cycling performance of less than 23% retention. In contrast, the xerogel composite electrodes can overcome these limitations in terms of a satisfied discharge performance of 1200 F/g and a good cycling retention more than 85% due to a stronger Ni(OH)2/CNT interface. The CNT bundles in the xerogel electrodes formed during the drying process can give a flat surface with small curvature, which facilitate the Ni(OH)2 nucleation and growth. Thanks for the support from the A star R-265-000-424-305.

Determination of Cd2+ in aqueous solution using polyindole-Ce(IV) vanadophosphate conductive nanocomposite ion-selective membrane electrode

NASA Astrophysics Data System (ADS)

Khan, Asif Ali; Quasim Khan, Mohd; Hussain, Rizwan

2017-09-01

In the present study an organic-inorganic nanocomposite ion exchanger Polyindole-Ce(IV) vanadophosphate (PIn-CVP) was synthesized via sol-gel process showing excellent ion exchange capacity (IEC‒1.90 meqg-1). The material was characterized by SEM, TEM, XRD, FTIR, and TGA. A heterogeneous ion exchange membrane of PIn-CVP (IEC‒0.90 meqg-1) was also prepared by solution casting method. PIn-CVP shows high electrical conductivity (5.5  ×  10-2 S cm-1) and it is stable up to 120 °C under ambient conditions. Cd2+ selective membrane electrode was fabricated and its linear working range (3.98  ×  10-7 M to 1.0  ×  10-1 M), response time (25 s), Nerstian slope 25.00 mV dec-1 and working pH range (4-7) were calculated. It was employed as an indicator electrode in the potentiometric titration of Cd2+.

Next generation solar cells using flexible transparent electrodes based on silver nanowires and grapheme

NASA Astrophysics Data System (ADS)

Alomairy, Sultan

Organic photovoltaic (OPV) devices have been developed extensively and optimised due to the use of nanomaterials in their construction. More recently, the demand for such devices to be flexible and mechanically robust has been a major area of research. Presently, Indium Tin Oxide (ITO) is the material that is used almost exclusively for transparent electrode. However, it has several drawbacks such as brittleness, high refractive index and high processing temperature. Furthermore, the price of ITO has been highly volatile due to scarcity of indium resources and the increased consumption of the material. Therefore, cheap, flexible and solution-processed transparent conductors are required for emerging optoelectronic devices with flexible construction which can be promising for wearable or environmentally adaptable devices purposes such as flexible solar cells and displays. Therefore, over the past decade an alternative material has been sought intensively, particularly in the need for producing large area flexible transparent electrodes. Many materials have been investigated but most investigations have focused on carbon nanotube (CNT), graphene flakes and metallic nanowires. Silver nanowires (Ag NWs) networks have been proven to show a high electrical conductivity with high optical transmittance. This special characteristic is desirable in transparent conductive electrodes in optoelectronic applications such as solar cells, light emitting diodes, and touch screen. On the other hand, Polymeric substrates that act as a non-brittle scaffold as well as protective packaging of the OPV are an essential element for such an “All-plastic” device. However, for such applications where the coating should be relatively hard a bottleneck to fabricating large area homogeneous films is associated with the formation of cracks as a result of local mismatches in mechanical properties during film formation. In this work, the fabrication and characterization of flexible transparent electrodes of Ag NWs on flexible substrates by spray deposition technique have been described. Furthermore, a way to enhance the electrical and mechanical properties of the Ag NWs transparent electrodes by incorporating a low density ensemble of graphene on top of the metal electrode networks using the Langmuir-Schafer has been achieved. Interestingly, the electrical conductivity in these hybrid electrodes is stable over relatively large strains during mechanical agitation indicating that such electrodes may have important application in future applications. Finally, producing crack-free monolayer latex over large area has been fabricated and characterised. Therefore, the polymer latex thin film has promising applications as purposes of hard coatings.

Lanthanum manganite-based air electrode for solid oxide fuel cells

DOEpatents

Ruka, Roswell J.; Kuo, Lewis; Li, Baozhen

1999-01-01

An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La.sub.w Ca.sub.x Ln.sub.y Ce.sub.z MnO.sub.3, wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics.

Few-layered CoHPO4.3H2O ultrathin nanosheets for high performance of electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Pang, Huan; Wang, Shaomei; Shao, Weifang; Zhao, Shanshan; Yan, Bo; Li, Xinran; Li, Sujuan; Chen, Jing; Du, Weimin

2013-06-01

Ultrathin cobalt phosphate (CoHPO4.3H2O) nanosheets are successfully synthesized by a one pot hydrothermal method. Novel CoHPO4.3H2O ultrathin nanosheets are assembled for constructing the electrodes of supercapacitors. Benefiting from the nanostructures, the as-prepared electrode shows a specific capacitance of 413 F g-1, and no obvious decay even after 3000 charge-discharge cycles. Such a quasi-two-dimensional material is a new kind of supercapacitor electrode material with high performance.Ultrathin cobalt phosphate (CoHPO4.3H2O) nanosheets are successfully synthesized by a one pot hydrothermal method. Novel CoHPO4.3H2O ultrathin nanosheets are assembled for constructing the electrodes of supercapacitors. Benefiting from the nanostructures, the as-prepared electrode shows a specific capacitance of 413 F g-1, and no obvious decay even after 3000 charge-discharge cycles. Such a quasi-two-dimensional material is a new kind of supercapacitor electrode material with high performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01460f

Lanthanum manganite-based air electrode for solid oxide fuel cells

DOEpatents

Ruka, R.J.; Kuo, L.; Li, B.

1999-06-29

An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO[sub 3]. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La[sub w]Ca[sub x]Ln[sub y]Ce[sub z]MnO[sub 3], wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics. 10 figs.

Energy band alignment of antiferroelectric (Pb,La)(Zr,Sn,Ti)O3

NASA Astrophysics Data System (ADS)

Klein, Andreas; Lohaus, Christian; Reiser, Patrick; Dimesso, Lucangelo; Wang, Xiucai; Yang, Tongqing

2017-06-01

The energy band alignment of antiferroelectric (Pb,La)(Zr,Sn,Ti)O3 is studied with photoelectron spectroscopy using interfaces with high work function RuO2 and low work function Sn-doped In2O3 (ITO). It is demonstrated how spectral deconvolution can be used to determine absolute Schottky barrier heights for insulating materials with a high accuracy. Using this approach it is found that the valence band maximum energy of (Pb,La)(Zr,Sn,Ti)O3 is found to be comparable to that of Pb- and Bi-containing ferroelectric materials, which is ∼1 eV higher than that of BaTiO3. The results provide additional evidence for the occupation of the 6s orbitals as origin of the higher valence band maximum, which is directly related to the electrical properties of such compounds. The results also verify that the energy band alignment determined by photoelectron spectroscopy of as-deposited electrodes is not influenced by polarisation. The electronic structure of (Pb,La)(Zr,Sn,Ti)O3 should enable doping of the material without strongly modifying its insulating properties, which is crucial for high energy density capacitors. Moreover, the position of the energy bands should result in a great freedom of selecting electrode materials in terms of avoiding charge injection.

Roles of surface chemistry on safety and electrochemistry in lithium ion batteries.

PubMed

Lee, Kyu Tae; Jeong, Sookyung; Cho, Jaephil

2013-05-21

Motivated by new applications including electric vehicles and the smart grid, interest in advanced lithium ion batteries has increased significantly over the past decade. Therefore, research in this field has intensified to produce safer devices with better electrochemical performance. Most research has focused on the development of new electrode materials through the optimization of bulk properties such as crystal structure, ionic diffusivity, and electric conductivity. More recently, researchers have also considered the surface properties of electrodes as critical factors for optimizing performance. In particular, the electrolyte decomposition at the electrode surface relates to both a lithium ion battery's electrochemical performance and safety. In this Account, we give an overview of the major developments in the area of surface chemistry for lithium ion batteries. These ideas will provide the basis for the design of advanced electrode materials. Initially, we present a brief background to lithium ion batteries such as major chemical components and reactions that occur in lithium ion batteries. Then, we highlight the role of surface chemistry in the safety of lithium ion batteries. We examine the thermal stability of cathode materials: For example, we discuss the oxygen generation from cathode materials and describe how cells can swell and heat up in response to specific conditions. We also demonstrate how coating the surfaces of electrodes can improve safety. The surface chemistry can also affect the electrochemistry of lithium ion batteries. The surface coating strategy improved the energy density and cycle performance for layered LiCoO2, xLi2MnO3·(1 - x)LiMO2 (M = Mn, Ni, Co, and their combinations), and LiMn2O4 spinel materials, and we describe a working mechanism for these enhancements. Although coating the surfaces of cathodes with inorganic materials such as metal oxides and phosphates improves the electrochemical performance and safety properties of batteries, the microstructure of the coating layers and the mechanism of action are not fully understood. Therefore, researchers will need to further investigate the surface coating strategy during the development of new lithium ion batteries.

Improved zinc electrode and rechargeable zinc-air battery

DOEpatents

Ross, P.N. Jr.

1988-06-21

The invention comprises an improved rechargeable zinc-air cell/battery having recirculating alkaline electrolyte and a zinc electrode comprising a porous foam support material which carries the active zinc electrode material. 5 figs.

Recent developments in nickel electrode analysis

NASA Technical Reports Server (NTRS)

Whiteley, Richard V.; Daman, M. E.; Kaiser, E. Q.

1991-01-01

Three aspects of nickel electrode analysis for Nickel-Hydrogen and Nickel-Cadmium battery cell applications are addressed: (1) the determination of active material; (2) charged state nickel (as NiOOH + CoOOH); and (3) potassium ion content in the electrode. Four deloading procedures are compared for completeness of active material removal, and deloading conditions for efficient active material analyses are established. Two methods for charged state nickel analysis are compared: the current NASA procedure and a new procedure based on the oxidation of sodium oxalate by the charged material. Finally, a method for determining potassium content in an electrode sample by flame photometry is presented along with analytical results illustrating differences in potassium levels from vendor to vendor and the effects of stress testing on potassium content in the electrode. The relevance of these analytical procedures to electrode performance is reviewed.

The impact of electrode materials on 1/f noise in piezoelectric AlN contour mode resonators

NASA Astrophysics Data System (ADS)

Kim, Hoe Joon; Jung, Soon In; Segovia-Fernandez, Jeronimo; Piazza, Gianluca

2018-05-01

This paper presents a detailed analysis on the impact of electrode materials and dimensions on flicker frequency (1/f) noise in piezoelectric aluminum nitride (AlN) contour mode resonators (CMRs). Flicker frequency noise is a fundamental noise mechanism present in any vibrating mechanical structure, whose sources are not generally well understood. 1 GHz AlN CMRs with three different top electrode materials (Al, Au, and Pt) along with various electrode lengths and widths are fabricated to control the overall damping acting on the device. Specifically, the use of different electrode materials allows control of thermoelastic damping (TED), which is the dominant damping mechanism for high frequency AlN CMRs and largely depends on the thermal properties (i.e. thermal diffusivities and expansion coefficients) of the metal electrode rather than the piezoelectric film. We have measured Q and 1/f noise of 68 resonators and the results show that 1/f noise decreases with increasing Q, with a power law dependence that is about 1/Q4. Interestingly, the noise level also depends on the type of electrode materials. Devices with Pt top electrode demonstrate the best noise performance. Our results help unveiling some of the sources of 1/f noise in these resonators, and indicate that a careful selection of the electrode material and dimensions could reduce 1/f noise not only in AlN-CMRs, but also in various classes of resonators, and thus enable ultra-low noise mechanical resonators for sensing and radio frequency applications.

Interlinked multiphase Fe-doped MnO2 nanostructures: a novel design for enhanced pseudocapacitive performance

NASA Astrophysics Data System (ADS)

Wang, Ziya; Wang, Fengping; Li, Yan; Hu, Jianlin; Lu, Yanzhen; Xu, Mei

2016-03-01

Structure designing and morphology control can lead to high performance pseudocapacitive materials for supercapacitors. In this work, we have designed interlinked multiphase Fe-doped MnO2 nanostructures (α-MnO2/R-MnO2/ε-MnO2) to enhance the electrochemical properties by a facile method. These hierarchical hollow microspheres assembled by interconnected nanoflakes, and with plenty of porous nanorods radiating from the spherical shells were hydrothermally obtained. The supercapacitor electrode prepared from the unique construction exhibits outstanding specific capacitance of 267.0 F g-1 even under a high mass loading (~5 mg cm-2). Obviously improved performances compared to pure MnO2 are also demonstrated with a good rate capability, high energy density (1.30 mW h cm-3) and excellent cycling stability of 100% capacitance retention after 2000 cycles at 2 A g-1. The synergistic effects of alternative crystal structures, appropriate crystallinity and optimal morphology are identified to be responsible for the observations. This rational multiphase composite strategy provides a promising idea for materials scientists to design and prepare scalable electrode materials for energy storage devices.Structure designing and morphology control can lead to high performance pseudocapacitive materials for supercapacitors. In this work, we have designed interlinked multiphase Fe-doped MnO2 nanostructures (α-MnO2/R-MnO2/ε-MnO2) to enhance the electrochemical properties by a facile method. These hierarchical hollow microspheres assembled by interconnected nanoflakes, and with plenty of porous nanorods radiating from the spherical shells were hydrothermally obtained. The supercapacitor electrode prepared from the unique construction exhibits outstanding specific capacitance of 267.0 F g-1 even under a high mass loading (~5 mg cm-2). Obviously improved performances compared to pure MnO2 are also demonstrated with a good rate capability, high energy density (1.30 mW h cm-3) and excellent cycling stability of 100% capacitance retention after 2000 cycles at 2 A g-1. The synergistic effects of alternative crystal structures, appropriate crystallinity and optimal morphology are identified to be responsible for the observations. This rational multiphase composite strategy provides a promising idea for materials scientists to design and prepare scalable electrode materials for energy storage devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08857g

Chemical insights into the roles of nanowire cores on the growth and supercapacitor performances of Ni-Co-O/Ni(OH)2 core/shell electrodes

PubMed Central

Yin, Xuesong; Tang, Chunhua; Zhang, Liuyang; Yu, Zhi Gen; Gong, Hao

2016-01-01

Nanostructured core/shell electrodes have been experimentally demonstrated promising for high-performance electrochemical energy storage devices. However, chemical insights into the significant roles of nanowire cores on the growth of shells and their supercapacitor behaviors still remain as a research shortfall. In this work, by substituting 1/3 cobalt in the Co3O4 nanowire core with nickel, a 61% enhancement of the specific mass-loading of the Ni(OH)2 shell, a tremendous 93% increase of the volumetric capacitance and a superior cyclability were achieved in a novel NiCo2O4/Ni(OH)2 core/shell electrode in contrast to a Co3O4/Ni(OH)2 one. A comparative study suggested that not only the growth of Ni(OH)2 shells but also the contribution of cores were attributed to the overall performances. Importantly, their chemical origins were revealed through a theoretical simulation of the core/shell interfacial energy changes. Besides, asymmetric supercapacitor devices and applications were also explored. The scientific clues and practical potentials obtained in this work are helpful for the design and analysis of alternative core/shell electrode materials. PMID:26857606

Chemical insights into the roles of nanowire cores on the growth and supercapacitor performances of Ni-Co-O/Ni(OH)₂ core/shell electrodes.

PubMed

Yin, Xuesong; Tang, Chunhua; Zhang, Liuyang; Yu, Zhi Gen; Gong, Hao

2016-02-09

Nanostructured core/shell electrodes have been experimentally demonstrated promising for high-performance electrochemical energy storage devices. However, chemical insights into the significant roles of nanowire cores on the growth of shells and their supercapacitor behaviors still remain as a research shortfall. In this work, by substituting 1/3 cobalt in the Co3O4 nanowire core with nickel, a 61% enhancement of the specific mass-loading of the Ni(OH)2 shell, a tremendous 93% increase of the volumetric capacitance and a superior cyclability were achieved in a novel NiCo2O4/Ni(OH)2 core/shell electrode in contrast to a Co3O4/Ni(OH)2 one. A comparative study suggested that not only the growth of Ni(OH)2 shells but also the contribution of cores were attributed to the overall performances. Importantly, their chemical origins were revealed through a theoretical simulation of the core/shell interfacial energy changes. Besides, asymmetric supercapacitor devices and applications were also explored. The scientific clues and practical potentials obtained in this work are helpful for the design and analysis of alternative core/shell electrode materials.

3D polypyrrole structures as a sensing material for glucose detection

NASA Astrophysics Data System (ADS)

Cysewska, Karolina; Szymańska, Magdalena; Jasiński, Piotr

2016-11-01

In this work, 3D polypyrrole (PPy) structures as material for glucose detection is proposed. Polypyrrole was electrochemically polymerized on platinum screen-printed electrode from an aqueous solution of lithium perchlorate and pyrrole. The growth mechanism of such PPy structures was studied by ex-situ scanning electron microscopy. Preliminary studies show that studied here PPy film is a good candidate as a sensing material for glucose biosensor. It exhibits very high sensitivity (28.5 mA·mM-1·cm-2) and can work without any additional dopants, mediators or enzymes. It was also shown that glucose detection depends on the PPy morphology. The same PPy material was immobilized with the glucose oxidase enzyme. Such material exhibited higher signal response, however it lost its stability very fast.

3D-printed conductive static mixers enable all-vanadium redox flow battery using slurry electrodes

NASA Astrophysics Data System (ADS)

Percin, Korcan; Rommerskirchen, Alexandra; Sengpiel, Robert; Gendel, Youri; Wessling, Matthias

2018-03-01

State-of-the-art all-vanadium redox flow batteries employ porous carbonaceous materials as electrodes. The battery cells possess non-scalable fixed electrodes inserted into a cell stack. In contrast, a conductive particle network dispersed in the electrolyte, known as slurry electrode, may be beneficial for a scalable redox flow battery. In this work, slurry electrodes are successfully introduced to an all-vanadium redox flow battery. Activated carbon and graphite powder particles are dispersed up to 20 wt% in the vanadium electrolyte and charge-discharge behavior is inspected via polarization studies. Graphite powder slurry is superior over activated carbon with a polarization behavior closer to the standard graphite felt electrodes. 3D-printed conductive static mixers introduced to the slurry channel improve the charge transfer via intensified slurry mixing and increased surface area. Consequently, a significant increase in the coulombic efficiency up to 95% and energy efficiency up to 65% is obtained. Our results show that slurry electrodes supported by conductive static mixers can be competitive to state-of-the-art electrodes yielding an additional degree of freedom in battery design. Research into carbon properties (particle size, internal surface area, pore size distribution) tailored to the electrolyte system and optimization of the mixer geometry may yield even better battery properties.

Electrochemical Reduction of Carbon Dioxide to Methanol by Direct Injection of Electrons into Immobilized Enzymes on a Modified Electrode.

PubMed

Schlager, Stefanie; Dumitru, Liviu Mihai; Haberbauer, Marianne; Fuchsbauer, Anita; Neugebauer, Helmut; Hiemetsberger, Daniela; Wagner, Annika; Portenkirchner, Engelbert; Sariciftci, Niyazi Serdar

2016-03-21

We present results for direct bio-electrocatalytic reduction of CO2 to C1 products using electrodes with immobilized enzymes. Enzymatic reduction reactions are well known from biological systems where CO2 is selectively reduced to formate, formaldehyde, or methanol at room temperature and ambient pressure. In the past, the use of such enzymatic reductions for CO2 was limited due to the necessity of a sacrificial co-enzyme, such as nicotinamide adenine dinucleotide (NADH), to supply electrons and the hydrogen equivalent. The method reported here in this paper operates without the co-enzyme NADH by directly injecting electrons from electrodes into immobilized enzymes. We demonstrate the immobilization of formate, formaldehyde, and alcohol dehydrogenases on one-and-the-same electrode for direct CO2 reduction. Carbon felt is used as working electrode material. An alginate-silicate hybrid gel matrix is used for the immobilization of the enzymes on the electrode. Generation of methanol is observed for the six-electron reduction with Faradaic efficiencies of around 10%. This method of immobilization of enzymes on electrodes offers the opportunity for electrochemical application of enzymatic electrodes to many reactions in which a substitution of the expensive sacrificial co-enzyme NADH is desired. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low resistivity contacts to YBa2Cu3O(7-x) superconductors

NASA Technical Reports Server (NTRS)

Hsi, Chi-Shiung; Haertling, Gene H.

1991-01-01

Silver, gold, platinum, and palladium metals were investigated as electroding materials for the YBa2Cu3O(7-x) superconductors. Painting, embedding, and melting techniques were used to apply the electrodes. Contact resistivities were determined by: (1) type of electrode; (2) firing conditions; and (3) application method. Electrodes fired for long times exhibited lower contact resistivities than those fired for short times. Low-resistivity contacts were found for silver and gold electrodes. Silver, which made good ohmic contact to the YBa2Cu3O(7-x) superconductor with low contact resistivities was found to be the best electroding material among the materials evaluated in this investigation.

White light-emitting organic electroluminescent devices

DOEpatents

Shiang, Joseph John; Duggal, Anil Raj; Parthasarathy, Gautam

2006-06-20

A light-emitting device comprises a light-emitting member, which comprises two electrodes, at least two organic electroluminescent ("EL") materials disposed between the electrodes, a charge blocking material disposed between the electrodes, and at least one photoluminescent ("PL") material. The light-emitting member emits electromagnetic ("EM") radiation having a first spectrum in response to a voltage applied across the two electrodes. The PL material absorbs a portion of the EM radiation emitted by the light-emitting member and emits EM radiation having second spectrum different than the first spectrum. Each of the organic EL materials emits EM radiation having a wavelength range selected from the group consisting of blue and red wavelength ranges.

MC3T3-E1 Cell Response to Ti1-xAgx and Ag-TiNx Electrodes Deposited on Piezoelectric Poly(vinylidene fluoride) Substrates for Sensor Applications.

PubMed

Marques, S M; Rico, P; Carvalho, I; Gómez Ribelles, J L; Fialho, L; Lanceros-Méndez, S; Henriques, M; Carvalho, S

2016-02-17

In the sensors field, titanium based coatings are being used for the acquisition/application of electrical signals from/to piezoelectric materials. In this particular case, sensors are used to detect dynamic mechanical loads at early stages after intervention of problems associated with prostheses implantation. The aim of this work is to select an adequate electrode for sensor applications capable, in an initial stage to avoid bone cell adhesion, but at a long stage, permit osteointegration and osteoinduction. This work reports on the evaluation of osteoblast MC3T3-E1 cells behavior in terms of proliferation, adhesion and long-term differentiation of two different systems used as sensor electrodes: Ti1-xAgx and Ag-TiNx deposited by d.c. and pulsed magnetron sputtering at room temperature on poly(vinylidene fluoride) (PVDF). The results indicated an improved effect of Ag-TiNx electrodes compared with Ti1-xAgx and TiN, in terms of diminished cell adhesion and proliferation at an initial cell culture stage. Nevertheless, when cell culture time is longer, cells grown onto Ag-TiNx electrodes are capable to proliferate and also differentiate at proper rates, indicating the suitability of this coating for sensor application in prostheses devices. Thus, the Ag-TiNx system was considered the most promising electrode for tissue engineering applications in the design of sensors for prostheses to detect dynamic mechanical loads.

Pt-Al2O3 dual layer atomic layer deposition coating in high aspect ratio nanopores.

PubMed

Pardon, Gaspard; Gatty, Hithesh K; Stemme, Göran; van der Wijngaart, Wouter; Roxhed, Niclas

2013-01-11

Functional nanoporous materials are promising for a number of applications ranging from selective biofiltration to fuel cell electrodes. This work reports the functionalization of nanoporous membranes using atomic layer deposition (ALD). ALD is used to conformally deposit platinum (Pt) and aluminum oxide (Al(2)O(3)) on Pt in nanopores to form a metal-insulator stack inside the nanopore. Deposition of these materials inside nanopores allows the addition of extra functionalities to nanoporous materials such as anodic aluminum oxide (AAO) membranes. Conformal deposition of Pt on such materials enables increased performances for electrochemical sensing applications or fuel cell electrodes. An additional conformal Al(2)O(3) layer on such a Pt film forms a metal-insulator-electrolyte system, enabling field effect control of the nanofluidic properties of the membrane. This opens novel possibilities in electrically controlled biofiltration. In this work, the deposition of these two materials on AAO membranes is investigated theoretically and experimentally. Successful process parameters are proposed for a reliable and cost-effective conformal deposition on high aspect ratio three-dimensional nanostructures. A device consisting of a silicon chip supporting an AAO membrane of 6 mm diameter and 1.3 μm thickness with 80 nm diameter pores is fabricated. The pore diameter is reduced to 40 nm by a conformal deposition of 11 nm Pt and 9 nm Al(2)O(3) using ALD.

Pt-Al2O3 dual layer atomic layer deposition coating in high aspect ratio nanopores

NASA Astrophysics Data System (ADS)

Pardon, Gaspard; Gatty, Hithesh K.; Stemme, Göran; van der Wijngaart, Wouter; Roxhed, Niclas

2013-01-01

Functional nanoporous materials are promising for a number of applications ranging from selective biofiltration to fuel cell electrodes. This work reports the functionalization of nanoporous membranes using atomic layer deposition (ALD). ALD is used to conformally deposit platinum (Pt) and aluminum oxide (Al2O3) on Pt in nanopores to form a metal-insulator stack inside the nanopore. Deposition of these materials inside nanopores allows the addition of extra functionalities to nanoporous materials such as anodic aluminum oxide (AAO) membranes. Conformal deposition of Pt on such materials enables increased performances for electrochemical sensing applications or fuel cell electrodes. An additional conformal Al2O3 layer on such a Pt film forms a metal-insulator-electrolyte system, enabling field effect control of the nanofluidic properties of the membrane. This opens novel possibilities in electrically controlled biofiltration. In this work, the deposition of these two materials on AAO membranes is investigated theoretically and experimentally. Successful process parameters are proposed for a reliable and cost-effective conformal deposition on high aspect ratio three-dimensional nanostructures. A device consisting of a silicon chip supporting an AAO membrane of 6 mm diameter and 1.3 μm thickness with 80 nm diameter pores is fabricated. The pore diameter is reduced to 40 nm by a conformal deposition of 11 nm Pt and 9 nm Al2O3 using ALD.

Long Life Nickel Electrodes for Nickel-Hydrogen Cells: Fiber Substrates Nickel Electrodes

NASA Technical Reports Server (NTRS)

Rogers, Howard H.

2000-01-01

Samples of nickel fiber mat electrodes were investigated over a wide range of fiber diameters, electrode thickness, porosity and active material loading levels. Thickness' were 0.040, 0.060 and 0.080 inches for the plaque: fiber diameters were primarily 2, 4, and 8 micron and porosity was 85, 90, and 95%. Capacities of 3.5 in. diameter electrodes were determined in the flooded condition with both 26 and 31% potassium hydroxide solution. These capacity tests indicated that the highest capacities per unit weight were obtained at the 90% porosity level with a 4 micron diameter fiber plaque. It appeared that the thinner electrodes had somewhat better performance, consistent with sintered electrode history. Limited testing with two-positive-electrode boiler plate cells was also carried out. Considerable difficulty with constructing the cells was encountered with short circuits the major problem. Nevertheless, four cells were tested. The cell with 95% porosity electrodes failed during conditioning cycling due to high voltage during charge. Discharge showed that this cell had lost nearly all of its capacity. The other three cells after 20 conditioning cycles showed capacities consistent with the flooded capacities of the electrodes. Positive electrodes made from fiber substrates may well show a weight advantage of standard sintered electrodes, but need considerably more work to prove this statement. A major problem to be investigated is the lower strength of the substrate compared to standard sintered electrodes. Problems with welding of leads were significant and implications that the electrodes would expand more than sintered electrodes need to be investigated. Loading levels were lower than had been expected based on sintered electrode experiences and the lower loading led to lower capacity values. However, lower loading causes less expansion and contraction during cycling so that stress on the substrate is reduced.

High work function materials for source/drain contacts in printed polymer thin film transistors

NASA Astrophysics Data System (ADS)

Sholin, V.; Carter, S. A.; Street, R. A.; Arias, A. C.

2008-02-01

Studies of materials for source-drain electrodes in ink-jet printed polymer-based thin film transistors (TFTs) are reported. Two systems are studied: a blend of Ag nanoparticles with poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and an ethylene glycol-doped PEDOT:PSS solution (modified-PEDOT). The semiconductor used is the polythiophene derivative poly [5,5'-bis(3-dodecyl-2-thienyl)-2,2,2'-bithiophene]. PEDOT:Ag blends and modified-PEDOT yield TFTs with mobilities around 10-2 and 10-3cm2/Vs, respectively, subthreshold slopes around 1.6V/decade and on-to-off current ratios of 106-107. Both systems show considerable improvement over printed TFTs with Ag nanoparticle source-drain electrodes. Results on film resistivity and morphology are discussed along with device characteristic analysis.

Coated carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

2006-12-12

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

Coated carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng [Newton, MA; Wen, Jian [Newton, MA; Chen, Jinghua [Chestnut Hill, MA; Huang, Zhongping [Belmont, MA; Wang, Dezhi [Wellesley, MA

2008-10-28

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

System for harvesting water wave energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhong Lin; Su, Yanjie; Zhu, Guang

A generator for harvesting energy from water in motion includes a sheet of a hydrophobic material, having a first side and an opposite second side, that is triboelectrically more negative than water. A first electrode sheet is disposed on the second side of the sheet of a hydrophobic material. A second electrode sheet is disposed on the second side of the sheet of a hydrophobic material and is spaced apart from the first electrode sheet. Movement of the water across the first side induces an electrical potential imbalance between the first electrode sheet and the second electrode sheet.

Facile Synthesis of Mixed Metal Organic Frameworks: Electrode Materials for Supercapacitor with Excellent Areal Capacitance and Operational Stability.

PubMed

Kazemi, Sayed Habib; Hosseinzadeh, Batoul; Kazemi, Hojjat; Kiani, Mohammad Ali; Hajati, Shaaker

2018-06-08

Electrode materials with high surface area, tailored pore size and efficient capability for ion insertion and enhanced transport of electrons and ions are needed for advanced supercapacitors. In the present study, a mixed metal organic framework (cobalt and manganese based MOF) was synthesized through a simple one pot solvothermal method and employed as the electrode material for supercapacitor. Notably, Co-Mn MOF electrode displayed a large surface area and excellent cycling stability (over 95% capacitance retention after 1500 cycles). Also, superior pseudocapacitive behavior was observed for Co-Mn MOF electrode in KOH electrolyte with an exceptional areal capacitance of 1.318 F cm-2. Moreover, an asymmetric supercapacitor was assembled using Co-Mn MOF and activated carbon electrode as positive and negative electrodes, respectively. The fabricated supercapacitor showed specific capacitances of 106.7 F g-1 at a scan rate of 10 mV s-1 and delivered maximum energy density of 30 Wh kg-1 at 2285.7 W kg-1. Our studies suggest the Co-Mn MOF as promising electrode materials for supercapacitor applications.

Nanoporous carbon-based electrodes for high strain ionomeric bending actuators

NASA Astrophysics Data System (ADS)

Palmre, Viljar; Brandell, Daniel; Mäeorg, Uno; Torop, Janno; Volobujeva, Olga; Punning, Andres; Johanson, Urmas; Kruusmaa, Maarja; Aabloo, Alvo

2009-09-01

Ionic polymer metal composites (IPMCs) are electroactive material devices that bend at low applied voltage (1-4 V). Inversely, a voltage is generated when the materials are deformed, which makes them useful both as sensors and actuators. In this paper, we propose two new highly porous carbon materials as electrodes for IPMC actuators, generating a high specific area, and compare their electromechanical performance with recently reported RuO2 electrodes and conventional IPMCs. Using a direct assembly process (DAP), we synthesize ionic liquid (Emi-Tf) actuators with either carbide-derived carbon (CDC) or coconut-shell-based activated carbon-based electrodes. The carbon electrodes were applied onto ionic liquid-swollen Nafion membranes using a direct assembly process. The study demonstrates that actuators based on carbon electrodes derived from TiC have the greatest peak-to-peak strain output, reaching up to 20.4 mɛ (equivalent to>2%) at a 2 V actuation signal, exceeding that of the RuO2 electrodes by more than 100%. The electrodes synthesized from TiC-derived carbon also exhibit significantly higher maximum strain rate. The differences between the materials are discussed in terms of molecular interactions and mechanisms upon actuation in the different electrodes.

Ion-plasma gun for ion-milling machine

DOEpatents

Kaminsky, Manfred S.; Campana, Jr., Thomas J.

1976-01-01

An ion gun includes an elongated electrode with a hollow end portion closed by a perforated end plate. The end plate is positioned parallel to a perforated flat electrode of opposite electrical polarity. An insulated sleeve encompasses the elongated electrode and extends outwardly from the perforated end towards the flat electrode. The sleeve length is separated into two portions of different materials. The first is formed of a high-temperature material that extends over the hollow portion of the elongated electrode where the arc is initiated by a point source electrode. The second sleeve portion extending over the remainder of the elongated electrode is of a resilient material for enhanced seal-forming ability and retention of plasma gas. Perforations are arranged in the flat electrode in a mutually opposing triangular pattern to project a plasma beam having a generally flat current profile towards a target requiring precision milling.

A polyoxovanadate as an advanced electrode material for supercapacitors.

PubMed

Chen, Han-Yi; Wee, Grace; Al-Oweini, Rami; Friedl, Jochen; Tan, Kim Soon; Wang, Yuxi; Wong, Chui Ling; Kortz, Ulrich; Stimming, Ulrich; Srinivasan, Madhavi

2014-07-21

Polyoxovanadate Na(6)V(10)O(28) is investigated for the first time as electrode material for supercapacitors (SCs). The electrochemical properties of Na(6)V(10)O(28) electrodes are studied in Li(+) -containing organic electrolyte (1 M LiClO(4) in propylene carbonate) by galvanostatic charge/discharge and cyclic voltammetry in a three-electrode configuration. Na(6)V(10)O(28) electrodes exhibit high specific capacitances of up to 354 F g(-1). An asymmetric SC with activated carbon as positive electrode and Na(6)V(10)O(28) as negative electrode is fabricated and exhibits a high energy density of 73 Wh kg(-1) with a power density of 312 W kg(-1), which successfully demonstrates that Na(6)V(10)O(28) is a promising electrode material for high-energy SC applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoporous materials for reducing the over potential of creating hydrogen by water electrolysis

DOEpatents

Anderson, Marc A.; Leonard, Kevin C.

2016-06-14

Disclosed is an electrolyzer including an electrode including a nanoporous oxide-coated conducting material. Also disclosed is a method of producing a gas through electrolysis by contacting an aqueous solution with an electrode connected to an electrical power source, wherein the electrode includes a nanoporous oxide-coated conducting material.

Reversibly immobilized biological materials in monolayer films on electrodes

DOEpatents

Weaver, P.F.; Frank, A.J.

1993-05-04

Methods and techniques are described for reversibly binding charged biological particles in a fluid medium to an electrode surface. The methods are useful in a variety of applications. The biological materials may include microbes, proteins, and viruses. The electrode surface may consist of reversibly electroactive materials such as polyvinylferrocene, silicon-linked ferrocene or quinone.

Reversibly immobilized biological materials in monolayer films on electrodes

DOEpatents

Weaver, Paul F.; Frank, Arthur J.

1993-01-01

Methods and techniques are described for reversibly binding charged biological particles in a fluid medium to an electrode surface. The methods are useful in a variety of applications. The biological materials may include microbes, proteins, and viruses. The electrode surface may consist of reversibly electroactive materials such as polyvinylferrocene, silicon-linked ferrocene or quinone.

New, Efficient, and Reliable Air Electrode Material for Proton-Conducting Reversible Solid Oxide Cells.

PubMed

Huan, Daoming; Shi, Nai; Zhang, Lu; Tan, Wenzhou; Xie, Yun; Wang, Wanhua; Xia, Changrong; Peng, Ranran; Lu, Yalin

2018-01-17

Driven by the demand to minimize fluctuation in common renewable energies, reversible solid oxide cells (RSOCs) have drawn increasing attention for they can operate either as fuel cells to produce electricity or as electrolysis cells to store electricity. Unfortunately, development of proton-conducting RSOCs (P-RSOCs) faces a major challenge of poor reliability because of the high content of steam involved in air electrode reactions, which could seriously decay the lifetime of air electrode materials. In this work, a very stable and efficient air electrode, SrEu 2 Fe 1.8 Co 0.2 O 7-δ (SEFC) with layer structure, is designed and deployed in P-RSOCs. X-ray diffraction analysis and High-angle annular dark-filed scanning transmission electron microscopy images of SEFC reveal that Sr atoms occupy the center of perovskite slabs, whereas Eu atoms arrange orderly in the rock-salt layer. Such a special structure of SEFC largely depresses its Lewis basicity and therefore its reactivity with steam. Applying the SEFC air electrode, our button switches smoothly between both fuel cell and electrolysis cell (EC) modes with no obvious degradation over a 135 h long-term test under wet H 2 (∼3% H 2 O) and 10% H 2 O-air atmospheres. A record of over 230 h is achieved in the long-term stability test in the EC mode, doubling the longest test that had been previously reported. Besides good stability, SEFC demonstrates great catalytic activity toward air electrode reactions when compared with traditional La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ air electrodes. This research highlights the potential of stable and efficient P-RSOCs as an important part in a sustainable new energy power system.

Theoretical Considerations for Improving the Pulse Power of a Battery through the Addition of a Second Electrochemically Active Material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knehr, K. W.; West, Alan C.

Here, porous electrode theory is used to conduct case studies for when the addition of a second electrochemically active material can improve the pulse-power performance of an electrode. Case studies are conducted for the positive electrode of a sodium metal-halide battery and the graphite negative electrode of a lithium “rocking chair” battery. The replacement of a fraction of the nickel chloride capacity with iron chloride in a sodium metal-halide electrode and the replacement of a fraction of the graphite capacity with carbon black in a lithium-ion negative electrode were both predicted to increase the maximum pulse power by up tomore » 40%. In general, whether or not a second electrochemically active material increases the pulse power depends on the relative importance of ohmic-to-charge transfer resistances within the porous structure, the capacity fraction of the second electrochemically active material, and the kinetic and thermodynamic parameters of the two active materials.« less

Theoretical Considerations for Improving the Pulse Power of a Battery through the Addition of a Second Electrochemically Active Material

DOE PAGES

Knehr, K. W.; West, Alan C.

2016-05-26

Here, porous electrode theory is used to conduct case studies for when the addition of a second electrochemically active material can improve the pulse-power performance of an electrode. Case studies are conducted for the positive electrode of a sodium metal-halide battery and the graphite negative electrode of a lithium “rocking chair” battery. The replacement of a fraction of the nickel chloride capacity with iron chloride in a sodium metal-halide electrode and the replacement of a fraction of the graphite capacity with carbon black in a lithium-ion negative electrode were both predicted to increase the maximum pulse power by up tomore » 40%. In general, whether or not a second electrochemically active material increases the pulse power depends on the relative importance of ohmic-to-charge transfer resistances within the porous structure, the capacity fraction of the second electrochemically active material, and the kinetic and thermodynamic parameters of the two active materials.« less

Solid state photosensitive devices which employ isolated photosynthetic complexes

DOEpatents

Peumans, Peter; Forrest, Stephen R.

2009-09-22

Solid state photosensitive devices including photovoltaic devices are provided which comprise a first electrode and a second electrode in superposed relation; and at least one isolated Light Harvesting Complex (LHC) between the electrodes. Preferred photosensitive devices comprise an electron transport layer formed of a first photoconductive organic semiconductor material, adjacent to the LHC, disposed between the first electrode and the LHC; and a hole transport layer formed of a second photoconductive organic semiconductor material, adjacent to the LHC, disposed between the second electrode and the LHC. Solid state photosensitive devices of the present invention may comprise at least one additional layer of photoconductive organic semiconductor material disposed between the first electrode and the electron transport layer; and at least one additional layer of photoconductive organic semiconductor material, disposed between the second electrode and the hole transport layer. Methods of generating photocurrent are provided which comprise exposing a photovoltaic device of the present invention to light. Electronic devices are provided which comprise a solid state photosensitive device of the present invention.

Architecture engineering of supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

Chen, Kunfeng; Li, Gong; Xue, Dongfeng

2016-02-01

The biggest challenge for today’s supercapacitor systems readily possessing high power density is their low energy density. Their electrode materials with controllable structure, specific surface area, electronic conductivity, and oxidation state, have long been highlighted. Architecture engineering of functional electrode materials toward powerful supercapacitor systems is becoming a big fashion in the community. The construction of ion-accessible tunnel structures can microscopically increase the specific capacitance and materials utilization; stiff 3D structures with high specific surface area can macroscopically assure high specific capacitance. Many exciting findings in electrode materials mainly focus on the construction of ice-folded graphene paper, in situ functionalized graphene, in situ crystallizing colloidal ionic particles and polymorphic metal oxides. This feature paper highlights some recent architecture engineering strategies toward high-energy supercapacitor electrode systems, including electric double-layer capacitance (EDLC) and pseudocapacitance.

High-Capacity, High-Voltage Composite Oxide Cathode Materials

NASA Technical Reports Server (NTRS)

Hagh, Nader M.

2015-01-01

This SBIR project integrates theoretical and experimental work to enable a new generation of high-capacity, high-voltage cathode materials that will lead to high-performance, robust energy storage systems. At low operating temperatures, commercially available electrode materials for lithium-ion (Li-ion) batteries do not meet energy and power requirements for NASA's planned exploration activities. NEI Corporation, in partnership with the University of California, San Diego, has developed layered composite cathode materials that increase power and energy densities at temperatures as low as 0 degC and considerably reduce the overall volume and weight of battery packs. In Phase I of the project, through innovations in the structure and morphology of composite electrode particles, the partners successfully demonstrated an energy density exceeding 1,000 Wh/kg at 4 V at room temperature. In Phase II, the team enhanced the kinetics of Li-ion transport and electronic conductivity at 0 degC. An important feature of the composite cathode is that it has at least two components that are structurally integrated. The layered material is electrochemically inactive; however, upon structural integration with a spinel material, the layered material can be electrochemically activated and deliver a large amount of energy with stable cycling.

Efficient Supercapacitor Energy Storage Using Conjugated Microporous Polymer Networks Synthesized from Buchwald-Hartwig Coupling.

PubMed

Liao, Yaozu; Wang, Haige; Zhu, Meifang; Thomas, Arne

2018-03-01

Supercapacitors have received increasing interest as energy storage devices due to their rapid charge-discharge rates, high power densities, and high durability. In this work, novel conjugated microporous polymer (CMP) networks are presented for supercapacitor energy storage, namely 3D polyaminoanthraquinone (PAQ) networks synthesized via Buchwald-Hartwig coupling between 2,6-diaminoanthraquinone and aryl bromides. PAQs exhibit surface areas up to 600 m 2 g -1 , good dispersibility in polar solvents, and can be processed to flexible electrodes. The PAQs exhibit a three-electrode specific capacitance of 576 F g -1 in 0.5 m H 2 SO 4 at a current of 1 A g -1 retaining 80-85% capacitances and nearly 100% Coulombic efficiencies (95-98%) upon 6000 cycles at a current density of 2 A g -1 . Asymmetric two-electrode supercapacitors assembled by PAQs show a capacitance of 168 F g -1 of total electrode materials, an energy density of 60 Wh kg -1 at a power density of 1300 W kg -1 , and a wide working potential window (0-1.6 V). The asymmetric supercapacitors show Coulombic efficiencies up to 97% and can retain 95.5% of initial capacitance undergo 2000 cycles. This work thus presents novel promising CMP networks for charge energy storage. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lightweight, durable lead-acid batteries

DOEpatents

Lara-Curzio, Edgar [Lenoir City, TN; An, Ke [Knoxville, TX; Kiggans, Jr., James O.; Dudney, Nancy J [Knoxville, TN; Contescu, Cristian I [Knoxville, TN; Baker, Frederick S [Oak Ridge, TN; Armstrong, Beth L [Clinton, TN

2011-09-13

A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

Lightweight, durable lead-acid batteries

DOEpatents

Lara-Curzio, Edgar; An, Ke; Kiggans, Jr., James O; Dudney, Nancy J; Contescu, Cristian I; Baker, Frederick S; Armstrong, Beth L

2013-05-21

A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

Materials and fabrication of electrode scaffolds for deposition of MnO2 and their true performance in supercapacitors

NASA Astrophysics Data System (ADS)

Cao, Jianyun; Li, Xiaohong; Wang, Yaming; Walsh, Frank C.; Ouyang, Jia-Hu; Jia, Dechang; Zhou, Yu

2015-10-01

MnO2 is a promising electrode material for high energy supercapacitors because of its large pseudo-capacitance. However, MnO2 suffers from low electronic conductivity and poor cation diffusivity, which results in poor utilization and limited rate performance of traditional MnO2 powder electrodes, obtained by pressing a mixed paste of MnO2 powder, conductive additive and polymer binder onto metallic current collectors. Developing binder-free MnO2 electrodes by loading nanoscale MnO2 deposits on pre-fabricated device-ready electrode scaffolds is an effective way to achieve both high power and energy performance. These electrode scaffolds, with interconnected skeletons and pore structures, will not only provide mechanical support and electron collection as traditional current collectors but also fast ion transfer tunnels, leading to high MnO2 utilization and rate performance. This review covers design strategies, materials and fabrication methods for the electrode scaffolds. Rational evaluation of the true performance of these electrodes is carried out, which clarifies that some of the electrodes with as-claimed exceptional performances lack potential in practical applications due to poor mass loading of MnO2 and large dead volume of inert scaffold materials/void spaces in the electrode structure. Possible ways to meet this challenge and bring MnO2 electrodes from laboratory studies to real-world applications are considered.

Drazenka Svedruzic | NREL

Science.gov Websites

intrinsically and extrinsically strained materials Electrochemical and biochemical CO2 reduction and C-C bond reduction, and C-C bond formation. Svedruzic started her career at NREL as a postdoctoral researcher working -electrochemistry and fuel-forming mechano-electrocatalysis on spring electrodes," J. Phys. Chem. C. (2014

NREL Develops High-Speed Scanner to Monitor Fuel Cell Material Defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

2015-09-01

This highlight describes results of recent work in which polymer electrolyte membrane fuel cell electrodes with intentionally introduced known defects were imaged and analyzed using a fuel cell scanner recently developed at NREL. The highlight is being developed for the September 2015 Alliance S&T Board meeting.

Neural electrode resilience against dielectric damage may be improved by use of highly doped silicon as a conductive material.

PubMed

Caldwell, Ryan; Sharma, Rohit; Takmakov, Pavel; Street, Matthew G; Solzbacher, Florian; Tathireddy, Prashant; Rieth, Loren

2018-01-01

Dielectric damage occurring in vivo to neural electrodes, leading to conductive material exposure and impedance reduction over time, limits the functional lifetime and clinical viability of neuroprosthetics. We used silicon micromachined Utah Electrode Arrays (UEAs) with iridium oxide (IrO x ) tip metallization and parylene C dielectric encapsulation to understand the factors affecting device resilience and drive improvements. In vitro impedance measurements and finite element analyses were conducted to evaluate how exposed surface area of silicon and IrO x affect UEA properties. Through an aggressive in vitro reactive accelerated aging (RAA) protocol, in vivo parylene degradation was simulated on UEAs to explore agreement with our models. Electrochemical properties of silicon and other common electrode materials were compared to help inform material choice in future neural electrode designs. Exposure of silicon on UEAs was found to primarily affect impedance at frequencies >1kHz, while characteristics at 1 kHz and below were largely unchanged. Post-RAA impedance reduction of UEAs was mitigated in cases where dielectric damage was more likely to expose silicon instead of IrO x . Silicon was found to have a per-area electrochemical impedance >10×higher than many common electrode materials regardless of doping level and resistivity, making it best suited for use as a low-shunting conductor. Non-semiconductor electrode materials commonly used in neural electrode design are more susceptible to shunting neural interface signals through dielectric defects, compared to highly doped silicon. Strategic use of silicon and similar materials may increase neural electrode robustness against encapsulation failures. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbon Nanotube Based Light Sensor

NASA Technical Reports Server (NTRS)

Wincheski, russell A. (Inventor); Smits, Jan M. (Inventor); Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Ingram, JoAnne L. (Inventor)

2006-01-01

A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of electrically non-conductive material with the CNT-based conductors being distributed in a spaced apart fashion about a periphery of the first electrode. Each CNT-based conductor is coupled on one end thereof to the first electrode and extends away from the first electrode to terminate at a second free end. A second or gate electrode is positioned on the non-conductive material layer and is spaced apart from the second free end of each CNT-based conductor. Coupled to the first and second electrode is a device for detecting electron transfer along the CNT-based conductors resulting from light impinging on the CNT-based conductors.

Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance.

PubMed

Asfaw, Habtom D; Roberts, Matthew R; Tai, Cheuk-Wai; Younesi, Reza; Valvo, Mario; Nyholm, Leif; Edström, Kristina

2014-08-07

In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm(-2) at 0.1 mA cm(-2) (lowest rate) and 1.1 mA h cm(-2) at 6 mA cm(-2) (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

Development of high-performance supercapacitor electrode derived from sugar industry spent wash waste.

PubMed

Mahto, Ashesh; Gupta, Rajeev; Ghara, Krishna Kanta; Srivastava, Divesh N; Maiti, Pratyush; D, Kalpana; Rivera, Paul-Zavala; Meena, R; Nataraj, S K

2017-10-15

This study aims at developing supercapacitor materials from sugar and distillery industry wastes, thereby mediating waste disposal problem through reuse. In a two-step process, biomethanated spent wash (BMSW) was acid treated to produce solid waste sludge and waste water with significantly reduced total organic carbon (TOC) and biological oxygen demand (BOD) content. Further, waste sludge was directly calcined in presence of activating agent ZnCl 2 in inert atmosphere resulting in high surface area (730-900m 2 g -1 ) carbon of unique hexagonal morphology. Present technique resulted in achieving two-faceted target of liquid-solid waste remediation and production of high-performance carbon material. The resulted high surface area carbon was tested in both three and two electrode systems. Electrochemical tests viz. cyclic voltammetry, galvanostatic charge-discharge and impedance measurement were carried out in aqueous KOH electrolyte yielding specific capacitance as high as 120Fg -1 , whereas all solid supercapacitor devised using PVA/H 3 PO 4 polyelectrolyte showed stable capacitance of 105Fg -1 at 0.2Ag -1 . The presence of transition metal particles and hetero-atoms on carbon surface were confirmed by XPS, EDX and TEM analysis which enhanced the conductivity and imparted pseudocapacitance to some extent into the working electrode. The present study successfully demonstrated production of high-performance electrode material from dirtiest wastewater making process green, sustainable and economically viable. Copyright © 2017. Published by Elsevier B.V.

Machining of AISI D2 Tool Steel with Multiple Hole Electrodes by EDM Process

NASA Astrophysics Data System (ADS)

Prasad Prathipati, R.; Devuri, Venkateswarlu; Cheepu, Muralimohan; Gudimetla, Kondaiah; Uzwal Kiran, R.

2018-03-01

In recent years, with the increasing of technology the demand for machining processes is increasing for the newly developed materials. The conventional machining processes are not adequate to meet the accuracy of the machining of these materials. The non-conventional machining processes of electrical discharge machining is one of the most efficient machining processes is being widely used to machining of high accuracy products of various industries. The optimum selection of process parameters is very important in machining processes as that of an electrical discharge machining as they determine surface quality and dimensional precision of the obtained parts, even though time consumption rate is higher for machining of large dimension features. In this work, D2 high carbon and chromium tool steel has been machined using electrical discharge machining with the multiple hole electrode technique. The D2 steel has several applications such as forming dies, extrusion dies and thread rolling. But the machining of this tool steel is very hard because of it shard alloyed elements of V, Cr and Mo which enhance its strength and wear properties. However, the machining is possible by using electrical discharge machining process and the present study implemented a new technique to reduce the machining time using a multiple hole copper electrode. In this technique, while machining with multiple holes electrode, fin like projections are obtained, which can be removed easily by chipping. Then the finishing is done by using solid electrode. The machining time is reduced to around 50% while using multiple hole electrode technique for electrical discharge machining.

Towards uniformly dispersed battery electrode composite materials: Characteristics and performance

DOE PAGES

Yo Han Kwon; Takeuchi, Esther S.; Huie, Matthew M.; ...

2016-01-14

Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches formore » improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. In conclusion, the study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials.« less

Towards uniformly dispersed battery electrode composite materials: Characteristics and performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yo Han Kwon; Takeuchi, Esther S.; Huie, Matthew M.

Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches formore » improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. In conclusion, the study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials.« less

Aqueous processing of composite lithium ion electrode material

DOEpatents

Li, Jianlin; Armstrong, Beth L.; Daniel, Claus; Wood, III, David L.

2017-06-20

A method of making a battery electrode includes the steps of dispersing an active electrode material and a conductive additive in water with at least one dispersant to create a mixed dispersion; treating a surface of a current collector to raise the surface energy of the surface to at least the surface tension of the mixed dispersion; depositing the dispersed active electrode material and conductive additive on a current collector; and heating the coated surface to remove water from the coating.

Aqueous processing of composite lithium ion electrode material

DOEpatents

Li, Jianlin; Armstrong, Beth L; Daniel, Claus; Wood, III, David L

2015-02-17

A method of making a battery electrode includes the steps of dispersing an active electrode material and a conductive additive in water with at least one dispersant to create a mixed dispersion; treating a surface of a current collector to raise the surface energy of the surface to at least the surface tension of the mixed dispersion; depositing the dispersed active electrode material and conductive additive on a current collector; and heating the coated surface to remove water from the coating.

Modified lithium vanadium oxide electrode materials products and methods

DOEpatents

Thackeray, Michael M.; Kahaian, Arthur J.; Visser, Donald R.; Dees, Dennis W.; Benedek, Roy

1999-12-21

A method of improving certain vanadium oxide formulations is presented. The method concerns fluorine doping formulations having a nominal formula of LiV.sub.3 O.sub.8. Preferred average formulations are provided wherein the average oxidation state of the vanadium is at least 4.6. Herein preferred fluorine doped vanadium oxide materials, electrodes using such materials, and batteries including at least one electrode therein comprising such materials are provided.

Characterization and Simulation of a New Design Parallel-Plate Ionization Chamber for CT Dosimetry at Calibration Laboratories

NASA Astrophysics Data System (ADS)

Perini, Ana P.; Neves, Lucio P.; Maia, Ana F.; Caldas, Linda V. E.

2013-12-01

In this work, a new extended-length parallel-plate ionization chamber was tested in the standard radiation qualities for computed tomography established according to the half-value layers defined at the IEC 61267 standard, at the Calibration Laboratory of the Instituto de Pesquisas Energéticas e Nucleares (IPEN). The experimental characterization was made following the IEC 61674 standard recommendations. The experimental results obtained with the ionization chamber studied in this work were compared to those obtained with a commercial pencil ionization chamber, showing a good agreement. With the use of the PENELOPE Monte Carlo code, simulations were undertaken to evaluate the influence of the cables, insulator, PMMA body, collecting electrode, guard ring, screws, as well as different materials and geometrical arrangements, on the energy deposited on the ionization chamber sensitive volume. The maximum influence observed was 13.3% for the collecting electrode, and regarding the use of different materials and design, the substitutions showed that the original project presented the most suitable configuration. The experimental and simulated results obtained in this work show that this ionization chamber has appropriate characteristics to be used at calibration laboratories, for dosimetry in standard computed tomography and diagnostic radiology quality beams.

Structural investigation of MF, RF and DC sputtered Mo thin films for backside photovoltaic electrode

NASA Astrophysics Data System (ADS)

Małek, Anna K.; Marszałek, Konstanty W.; Rydosz, Artur M.

2016-12-01

Recently photovoltaics attracts much attention of research and industry. The multidirectional studies are carried out in order to improve solar cells performance, the innovative materials are still searched and existing materials and technology are optimized. In the multilayer structure of CIGS solar cells molybdenum (Mo) layer is used as a back contact. Mo layers meet all requirements for back side electrode: low resistivity, good adhesion to the substrate, high optical reflection in the visible range, columnar structure for Na ions diffusion, formation of an ohmic contact with the ptype CIGS absorber layer, and high stability during the corrosive selenization process. The high adhesion to the substrate and low resistivity in single Mo layer is difficult to be achieved because both properties depend on the deposition parameters, particularly on working gas pressure. Therefore Mo bilayers are applied as a back contact for CIGS solar cells. In this work the Mo layers were deposited by medium frequency sputtering at different process parameters. The effect of substrate temperature within the range of 50°C-200°C and working gas pressure from 0.7 mTorr to 7 mTorr on crystalline structure of Mo layers was studied.

Electrolytic dissolver

DOEpatents

Wheelwright, E.J.; Fox, R.D.

1975-08-26

This patent related to an electrolytic dissolver wherein dissolution occurs by solution contact including a vessel of electrically insulative material, a fixed first electrode, a movable second electrode, means for insulating the electrodes from the material to be dissolved while permitting a free flow of electrolyte therebetween, means for passing a direct current between the electrodes and means for circulating electrolyte through the dissolver. (auth)

Visualizing the Zero-Potential Line of Bipolar Electrodes with Arbitrary Geometry.

PubMed

Li, Meng; Liu, Shasha; Jiang, Yingyan; Wang, Wei

2018-06-05

In a typical bipolar electrochemistry (BPE) configuration, voltage applied between the two driving electrodes induced a potential drop through solution filled in the microchannel, resulting in an interfacial potential difference between solution and BPE varied along the BPE. In the present work, we employed a recently developed plasmonic imaging technique to map the distribution of surface potential of bipolar electrodes with various geometries including round, triangle, hexagon, star, and rhombus shapes under the nonfaradaic charging process, from which the line of zero potential (LZP) was visualized and determined. We further investigated the dependence of LZP on electrode geometry and the distribution of external electric field and explained the experimental results with a charge balance mechanism. The triangular and star-shaped BPEs show quite different LZP features from the other ones with symmetrical geometry. These experimentally obtained potential distributions are all in good agreement with electromagnetic simulations. Finally, the line of zero overpotential (LZO) of the triangular-shaped BPE under faradaic reactions were investigated. The results confirm the shift of LZO when faradaic reactions occurred at the corresponding ends of BPE. The present work demonstrates the first experimental capability to map the potential distribution of BPE with arbitrary geometry under an arbitrary driving field. It is anticipated to help the design and optimization on the geometry of electrodes and microchannels with implications for boosting their applications in chemical sensing and materials synthesis.

Method for fabrication of electrodes

DOEpatents

Jankowski, Alan F.; Morse, Jeffrey D.; Barksdale, Randy

2004-06-22

Described herein is a method to fabricate porous thin-film electrodes for fuel cells and fuel cell stacks. Furthermore, the method can be used for all fuel cell electrolyte materials which utilize a continuous electrolyte layer. An electrode layer is deposited on a porous host structure by flowing gas (for example, Argon) from the bottomside of the host structure while simultaneously depositing a conductive material onto the topside of the host structure. By controlling the gas flow rate through the pores, along with the process conditions and deposition rate of the thin-film electrode material, a film of a pre-determined thickness can be formed. Once the porous electrode is formed, a continuous electrolyte thin-film is deposited, followed by a second porous electrode to complete the fuel cell structure.

Conjugated Polymer Zwitterions: Efficient Interlayer Materials in Organic Electronics.

PubMed

Liu, Yao; Duzhko, Volodimyr V; Page, Zachariah A; Emrick, Todd; Russell, Thomas P

2016-11-15

Conjugated polymer zwitterions (CPZs) are neutral, hydrophilic, polymer semiconductors. The pendent zwitterions, viewed as side chain dipoles, impart solubility in polar solvents for solution processing, and open opportunities as interfacial components of optoelectronic devices, for example, between metal electrodes and organic semiconductor active layers. Such interlayers are crucial for defining the performance of organic electronic devices, e.g., field-effect transistors (OFETs), light-emitting diodes (OLEDs), and photovoltaics (OPVs), all of which consist of multilayer structures. The interlayers reduce the Schottky barrier height and thus improve charge injection in OFETs and OLEDs. In OPVs, the interlayers serve to increase the built-in electric potential difference (V bi ) across the active layer, ensuring efficient extraction of photogenerated charge carriers. In general, polar and even charged electronically active polymers have gained recognition for their ability to modify metal/semiconductor interfaces to the benefit of organic electronics. While conjugated polyelectrolytes (CPEs) as interlayer materials are well-documented, open questions remain about the role of mobile counterions in CPE-containing devices. CPZs possess the processing advantages of CPEs, but as neutral molecules lack any potential complications associated with counterions. The electronic implications of CPZs on metal electrodes stem from the orientation of the zwitterion dipole moment in close proximity to the metal surface, and the resultant surface-induced polarization. This generates an interfacial dipole (Δ) at the CPZ/metal interface, altering the work function of the electrode, as confirmed by ultraviolet photoelectron spectroscopy (UPS), and improving device performance. An ideal cathode interlayer would reduce electrode work function, have orthogonal processability to the active layer, exhibit good film forming properties (i.e., wettability/uniformity), prevent exciton quenching, possess optimal electron affinity that neither limits the work function reduction nor impedes the charge extraction, transport electrons selectively, and exhibit long-term stability. Our recent discoveries show that CPZs achieve many of these attributes, and are poised for further expansion and development in the interfacial science of organic electronics. This Account reviews a recent collaboration that began with the synthesis of CPZs and a study of their structural and electronic properties on metals, then extended to their application as interlayer materials for OPVs. We discuss CPZ structure-property relationships based on several material platforms, ranging from homopolymers to copolymers, and from materials with intrinsic p-type conjugated backbones to those with intrinsic n-type conjugated backbones. We discuss key components of such interlayers, including (i) the origin of work function reduction of CPZ interlayers on metals; (ii) the role of the frontier molecular orbital energy levels and their trade-offs in optimizing electronic and device properties; and (iii) the role of polymer conductivity type and the magnitude of charge carrier mobility. Our motivation is to present our prior use and current understanding of CPZs as interlayer materials in organic electronics, and describe outstanding issues and future potential directions.

Electrode materials for rechargeable batteries

DOEpatents

Abouimrane, Ali; Amine, Khalil

2015-04-14

Selenium or selenium-containing compounds may be used as electroactive materials in electrodes or electrochemical devices. The selenium or selenium-containing compound is mixed with a carbon material.

Perovskite electrodes and method of making the same

DOEpatents

Seabaugh, Matthew M [Columbus, OH; Swartz, Scott L [Columbus, OH

2009-09-22

The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

Perovskite electrodes and method of making the same

DOEpatents

Seabaugh, Matthew M.; Swartz, Scott L.

2005-09-20

The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

Materials for suspension (semi-solid) electrodes for energy and water technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hatzell, Kelsey B.; Boota, Muhammad; Gogotsi, Yury

2015-01-01

Suspension or semi-solid electrodes have recently gained increased attention for large-scale applications such as grid energy storage, capacitive water deionization, and wastewater treatment. A suspension electrode is a multiphase material system comprised of an active (charge storing) material suspended in ionic solution (electrolyte). Gravimetrically, the electrolyte is the majority component and aids in physical transport of the active material. For the first time, this principle enables, scalability of electrochemical energy storage devices (supercapacitors and batteries) previously limited to small and medium scale applications. This critical review describes the ongoing material challenges encompassing suspension-based systems. The research described here combines classicalmore » aspects of electrochemistry, colloidal science, material science, fluid mechanics, and rheology to describe ion and charge percolation, adsorption of ions, and redox charge storage processes in suspension electrodes. Our review summarizes the growing inventory of material systems, methods and practices used to characterize suspension electrodes, and describes universal material system properties (rheological, electrical, and electrochemical) that are pivotal in the design of high performing systems. We include a discussion of the primary challenges and future research directions.« less

Nanostructured mesophase electrode materials: modulating charge-storage behavior by thermal treatment.

PubMed

Kong, Hye Jeong; Kim, Saerona; Le, Thanh-Hai; Kim, Yukyung; Park, Geunsu; Park, Chul Soon; Kwon, Oh Seok; Yoon, Hyeonseok

2017-11-16

3D nanostructured carbonaceous electrode materials with tunable capacitive phases were successfully developed using graphene/particulate polypyrrole (PPy) nanohybrid (GPNH) precursors without a separate process for incorporating heterogeneous species. The electrode material, namely carbonized GPNHs (CGPNHs) featured a mesophase capacitance consisting of both electric double-layer (EDL) capacitive and pseudocapacitive elements at the molecular level. The ratio of EDL capacitive element to pseudocapacitive element (E-to-P) in the mesophase electrode materials was controlled by varying the PPy-to-graphite weight (P w /G w ) ratio and by heat treatment (T H ), which was demonstrated by characterizing the CGPNHs with elemental analysis, cyclic voltammetry, and a charge/discharge test. The concept of the E-to-P ratio (EPR) index was first proposed to easily identify the capacitive characteristics of the mesophase electrode using a numerical algorithm, which was reasonably consistent with the experimental findings. Finally, the CGPNHs were integrated into symmetric two-electrode capacitor cells, which rendered excellent energy and power densities in both aqueous and ionic liquid electrolytes. It is anticipated that our approach could be widely extended to fabricating versatile hybrid electrode materials with estimation of their capacitive characteristics.

Repair welding of cast iron coated electrodes

NASA Astrophysics Data System (ADS)

Żuk, M.; Górka, J.; Dojka, R.; Czupryński, A.

2017-08-01

Welding cast iron is a complex production procedure. Repair welding was used to repair damaged or poorly made castings. This is due to a tendency to cracking of the material during welding as well as after it. Welding cast iron can be carried out on hot or on cold. Hot welding requires high heat material and the use of welding material in the form of cast iron. In the case of cold welding, it is possible to use different materials. Mostly used filler metals are nickel and copper based. The work shows the course of research concerning repairmen of ductile iron with arc welding method. For the reparation process four types of ESAB company coated electrodes dedicated for cast iron were used with diameter 3.2 and 4 mm: ES 18-8-6B (4mm), EB 150 (4mm), OK NiCl, EŻM. In the cast iron examined during the testing grooves were made using plasma methods, in order to simulate the removed casting flaws. Then the welding process with coated electrodes was executed. The process utilized low welding current row of 100A, so there would only be a small amount of heat delivered to the heat affected zone (HAZ). Short stitches were made, after welding it was hammered, in order to remove stresses. After the repair welding the part of studies commenced which purpose was finding surface defects using visual testing (VT) and penetration testing (PT). In the second part, a series of macro and microscopic studies were executed witch the purpose of disclosuring the structure. Then the hardness tests for welds cross sections were performed. An important aspect of welding cast iron is the colour of the padding weld after welding, more precisely the difference between the base material and padding weld, the use of different materials extra gives the extra ability to select the best variant. The research of four types of coated electrode was executed, based on the demands the best option in terms of aesthetic, strength and hardness.

Free-standing three-dimensional graphene/manganese oxide hybrids as binder-free electrode materials for energy storage applications.

PubMed

Zhu, Xiaoli; Zhang, Peng; Xu, Shan; Yan, Xingbin; Xue, Qunji

2014-07-23

Novel three-dimensional (3D) hybrid materials, i.e., free-standing 3D graphene-supported MnO2 nanosheets, are prepared by a simple and controllable solution-phase assembly process. Characterization results show that MnO2 nanosheets are uniformly anchored on a 3D graphene framework with strong adhesion and the integral hybrids show desirable mechanical strength. Such unique structure of 3D graphene/MnO2 hybrids thus provides the right characteristics of binder-free electrode materials and could enable the design of different kinds of high-performance energy storage devices. Especially, an advanced asymmetric supercapacitor is built by using a 3D graphene/MnO2 hybrid and a 3D graphene as two electrodes, and it is able to work reversibly in a full operation voltage region of 0-3.5 V in an ionic liquid electrolyte and thus exhibits a high energy density of 68.4 Wh/kg. As the cathode materials for Li-O2 and Li-MnO2 batteries, the 3D graphene/MnO2 hybrids exhibit outstanding performances, including good catalytic capability, high reversible capacity and desirable cycling stability. The results presented here may pave a way for new promising applications of such 3D graphene/MnO2 hybrids in advanced electrochemical energy storage devices.

Micro-Intertexture Carbon-Free Iron Sulfides as Advanced High Tap Density Anodes for Rechargeable Batteries.

PubMed

Xiao, Ying; Hwang, Jang-Yeon; Sun, Yang-Kook

2017-11-15

Numerous materials have been considered as promising electrode materials for rechargeable batteries; however, developing efficient materials to achieving good cycling performance and high volumetric energy capacity simultaneously remains a great challenge. Considering the appealing properties of iron sulfides, which include low cost, high theoretical capacity, and favorable electrochemical conversion mechanism, in this work, we demonstrate the feasibility of carbon-free microscale Fe 1-x S as high-efficiency anode materials for rechargeable batteries by designing hierarchical intertexture architecture. The as-prepared intertexture Fe 1-x S microspheres constructed from nanoscale units take advantage of both the long cycle life of nanoscale units and the high tap density (1.13 g cm -3 ) of the micro-intertexture Fe 1-x S. As a result, high capacities of 1089.2 mA h g -1 (1230.8 mA h cm -3 ) and 624.7 mA h g -1 (705.9 mA h cm -3 ) were obtained after 100 cycles at 1 A g -1 in Li-ion and Na-ion batteries, respectively, demonstrating one of the best performances for iron sulfide-based electrodes. Even after deep cycling at 20 A g -1 , satisfactory capacities could be retained. Related results promote the practical application of metal sulfides as high-capacity electrodes with high rate capability for next-generation rechargeable batteries.

Improvements to Zirconia Thick-Film Oxygen Sensors

NASA Astrophysics Data System (ADS)

Maskell, William C.; Brett, Daniel J. L.; Brandon, Nigel P.

2013-06-01

Thick-film zirconia gas sensors are normally screen-printed onto a planar substrate. A sandwich of electrode-electrolyte-electrode is fired at a temperature sufficient to instigate sintering of the zirconia electrolyte. The resulting porous zirconia film acts as both the electrolyte and as the diffusion barrier through which oxygen diffuses. The high sintering temperature results in de-activation of the electrodes so that sensors must be operated at around 800 °C for measurements in the percentage range of oxygen concentration. This work shows that the use of cobalt oxide as a sintering aid allows reduction of the sensor operating temperature by 100-200 °C with clear benefits. Furthermore, an interesting and new technique is presented for the investigation of the influence of dopants and of the through-porosity of ionically-conducting materials.

Fabrication and RF characterization of zinc oxide based Film Bulk Acoustic Resonator

NASA Astrophysics Data System (ADS)

Patel, Raju; Bansal, Deepak; Agrawal, Vimal Kumar; Rangra, Kamaljit; Boolchandani, Dharmendar

2018-06-01

This work reports fabrication and characterization of Film Bulk Acoustic Resonator (FBAR) to improve the performance characteristics for RF filter and sensing application. Zinc oxide as a piezoelectric (PZE) material was deposited on an aluminum bottom electrode using an RF magnetron sputtering, at room temperature, and gold as top electrode for the resonator. Tetramethyl ammonium hydroxide (TMAH) setup was used for bulk silicon etching to make back side cavity to confine the acoustic signals. The transmission characteristics show that the FBARs have a central frequency at 1.77 GHz with a return loss of -10.7 dB.

Electrochemical and kinetic studies of ultrafast laser structured LiFePO4 electrodes

NASA Astrophysics Data System (ADS)

Mangang, M.; Gotcu-Freis, P.; Seifert, H. J.; Pfleging, W.

2015-03-01

Due to a growing demand of cost-efficient lithium-ion batteries with an increased energy and power density as well as an increased life-time, the focus is set on intercalation cathode materials like LiFePO4. It has a high practical capacity, is environmentally friendly and has low material costs. However, its low electrical conductivity and low ionic diffusivity are major drawbacks for its use in electrochemical storage devices or electric vehicles. By adding conductive agents, the electrical conductivity can be enhanced. By increasing the surface of the cathode material which is in direct contact with the liquid electrolyte the lithium-ion diffusion kinetics can be improved. A new approach to increase the surface of the active material without changing the active particle packing density or the weight proportion of carbon black is the laser-assisted generation of 3D surface structures in electrode materials. In this work, ultrafast laser radiation was used to create a defined surface structure in LiFePO4 electrodes. It was shown that by using ultrashort laser pulses instead of nanosecond laser pulses, the ablation efficiency could be significantly increased. Furthermore, melting and debris formation were reduced. To investigate the diffusion kinetics, electrochemical methods such as cyclic voltammetry and galvanostatic intermittent titration technique were applied. It could be shown that due to a laser generated 3D structure, the lithium-ion diffusion kinetic, the capacity retention and cell life-time can be significantly improved.

Interfaces and Materials in Lithium Ion Batteries: Challenges for Theoretical Electrochemistry.

PubMed

Kasnatscheew, Johannes; Wagner, Ralf; Winter, Martin; Cekic-Laskovic, Isidora

2018-04-18

Energy storage is considered a key technology for successful realization of renewable energies and electrification of the powertrain. This review discusses the lithium ion battery as the leading electrochemical storage technology, focusing on its main components, namely electrode(s) as active and electrolyte as inactive materials. State-of-the-art (SOTA) cathode and anode materials are reviewed, emphasizing viable approaches towards advancement of the overall performance and reliability of lithium ion batteries; however, existing challenges are not neglected. Liquid aprotic electrolytes for lithium ion batteries comprise a lithium ion conducting salt, a mixture of solvents and various additives. Due to its complexity and its role in a given cell chemistry, electrolyte, besides the cathode materials, is identified as most susceptible, as well as the most promising, component for further improvement of lithium ion batteries. The working principle of the most important commercial electrolyte additives is also discussed. With regard to new applications and new cell chemistries, e.g., operation at high temperature and high voltage, further improvements of both active and inactive materials are inevitable. In this regard, theoretical support by means of modeling, calculation and simulation approaches can be very helpful to ex ante pre-select and identify the aforementioned components suitable for a given cell chemistry as well as to understand degradation phenomena at the electrolyte/electrode interface. This overview highlights the advantages and limitations of SOTA lithium battery systems, aiming to encourage researchers to carry forward and strengthen the research towards advanced lithium ion batteries, tailored for specific applications.

Electrode structure and methods of making same

DOEpatents

Ruud, James Anthony; Browall, Kenneth Walter; Rehg, Timothy Joseph; Renou, Stephane; Striker, Todd-Michael

2010-04-06

A method of making an electrode structure is provided. The method includes disposing an electrocatalytic material on an electrode, applying heat to the electrocatalytic material to form a volatile oxide of the electrocatalytic material, and applying a voltage to the electrode to reduce the volatile oxide to provide a number of nano-sized electrocatalytic particles on or proximate to a triple phase boundary, where the number of nano-sized electrocatalytic particles is greater on or proximate to the triple phase boundary than in an area that is not on or proximate to the triple phase boundary, and where the triple phase boundary is disposed on the electrode.

Preparation of Carbon-Chitosan-Polyvinyl Chloride (CC-PVC) Material and its Application to Electrochemical Degradation of Methylene Blue in Sodium Chloride Solution

NASA Astrophysics Data System (ADS)

Riyanto; Prawidha, A. D.

2018-01-01

Electrochemical degradation of methylene blue using Carbon-Chitosan-Polyvinyl Chloride (CC-PVC) electrode in sodium chloride have been done. The aim of this work was to degradation of methylene blue using Carbon-Chitosan-Polyvinyl Chloride (CC-PVC). Carbon chitosan composite electrode was preparing by Carbon and Chitosan powder and PVC in 4 mL tetrahydrofuran (THF) solvent and swirled flatly to homogeneous followed by drying in an oven at 100 °C for 3 h. The mixture was placed in stainless steel mould and pressed at 10 ton/cm2. Sodium chloride was used electrolyte solution. The effects of the current and electrolysis time were investigated using spectrophotometer UV-Visible. The experimental results showed that the carbon-chitosan composite electrode have higher effect in the electrochemical degradation of methylene blue in sodium chloride. Based on UV-visible spectra analysis shows current and electrolysis time has high effect to degradation of methylene blue in sodium chloride. Chitosan and polyvinyl chloride can strengthen the bond between the carbons so that the material has the high stability and conductivity. As conclusions is Carbon-Chitosan-Polyvinyl Chloride (CC-PVC) electrode have a high electrochemical activity for degradation of methylene blue in sodium chloride.

Trace level voltammetric determination of heavy metals and total mercury in tea matrices (Camellia sinensis).

PubMed

Melucci, Dora; Locatelli, Marcello; Locatelli, Clinio

2013-12-01

An analytical procedure regarding the voltammetric determination of mercury(II), copper(II), lead(II), cadmium(II) and zinc(II) by square wave anodic stripping voltammetry (SWASV) in matrices involved in food chain is proposed. In particular, tea leaves were analyzed as real samples. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture; 0.01 mol L(-1) EDTA-Na2+ 0.15 mol L(-1) NaCl + 0.5 mol L(-1) HCl was employed as the supporting electrolyte. The voltammetric measurements were carried out using a conventional three electrode cell, employing, as working electrodes, a gold electrode (GE) and a stationary hanging mercury drop electrode (HMDE). The analytical procedure has been verified on the standard reference materials Spinach Leaves NIST-SRM 1570a, Tomato Leaves NIST-SRM 1573a and Apple Leaves NIST-SRM 1515. For all the elements, the precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3-5%, while the trueness, expressed as relative error (e) was of the order of 3-7%. Once set up on the standard reference materials, the analytical procedure was applied to commercial tea leaves samples. A critical comparison with spectroscopic measurements is also discussed.

Transitions from near-surface to interior redox upon lithiation in conversion electrode materials.

PubMed

He, Kai; Xin, Huolin L; Zhao, Kejie; Yu, Xiqian; Nordlund, Dennis; Weng, Tsu-Chien; Li, Jing; Jiang, Yi; Cadigan, Christopher A; Richards, Ryan M; Doeff, Marca M; Yang, Xiao-Qing; Stach, Eric A; Li, Ju; Lin, Feng; Su, Dong

2015-02-11

Nanoparticle electrodes in lithium-ion batteries have both near-surface and interior contributions to their redox capacity, each with distinct rate capabilities. Using combined electron microscopy, synchrotron X-ray methods and ab initio calculations, we have investigated the lithiation pathways that occur in NiO electrodes. We find that the near-surface electroactive (Ni(2+) → Ni(0)) sites saturated very quickly, and then encounter unexpected difficulty in propagating the phase transition into the electrode (referred to as a "shrinking-core" mode). However, the interior capacity for Ni(2+) → Ni(0) can be accessed efficiently following the nucleation of lithiation "fingers" that propagate into the sample bulk, but only after a certain incubation time. Our microstructural observations of the transition from a slow shrinking-core mode to a faster lithiation finger mode corroborate with synchrotron characterization of large-format batteries and can be rationalized by stress effects on transport at high-rate discharge. The finite incubation time of the lithiation fingers sets the intrinsic limitation for the rate capability (and thus the power) of NiO for electrochemical energy storage devices. The present work unravels the link between the nanoscale reaction pathways and the C-rate-dependent capacity loss and provides guidance for the further design of battery materials that favors high C-rate charging.

Electrode Slurry Particle Density Mapping Using X-ray Radiography

DOE PAGES

Higa, Kenneth; Zhao, Hui; Parkinson, Dilworth Y.; ...

2017-01-05

The internal structure of a porous electrode strongly influences battery performance. Understanding the dynamics of electrode slurry drying could aid in engineering electrodes with desired properties. For instance, one might monitor the dynamic, spatially-varying thickness near the edge of a slurry coating, as it should lead to non-uniform thickness of the dried film. This work examines the dynamic behavior of drying slurry drops consisting of SiO x and carbon black particles in a solution of carboxymethylcellulose and deionized water, as an experimental model of drying behavior near the edge of a slurry coating. An X-ray radiography-based procedure is developed tomore » calculate the evolving spatial distribution of active material particles from images of the drying slurry drops. To the authors’ knowledge, this study is the first to use radiography to investigate battery slurry drying, as well as the first to determine particle distributions from radiography images of drying suspensions. The dynamic results are consistent with tomography reconstructions of the static, fully-dried films. It is found that active material particles can rapidly become non-uniformly distributed within the drops. Heating can promote distribution uniformity, but seemingly must be applied very soon after slurry deposition. Higher slurry viscosity is found to strongly restrain particle redistribution.« less

Characterization of honeycomb-like "β-Ni(OH) 2" thin films synthesized by chemical bath deposition method and their supercapacitor application

NASA Astrophysics Data System (ADS)

Patil, U. M.; Gurav, K. V.; Fulari, V. J.; Lokhande, C. D.; Joo, Oh Shim

Nanostructured nickel hydroxide thin films are synthesized via a simple chemical bath deposition (CBD) method using nickel nitrate Ni(NO 3) 2 as the starting material. The deposition process is based on the thermal decomposition of ammonia-complexed nickel ions at 333 K. The structural, surface morphological, optical, electrical and electrochemical properties of the films are examined. The nanocrystalline "β" phase of Ni(OH) 2 is confirmed by the X-ray diffraction analysis. Scanning electron microscopy reveals a macroporous and interconnected honeycomb-like morphology. Optical absorption studies show that "β-Ni(OH) 2" has a wide optical band-gap of 3.95 eV. The negative temperature coefficient of the electrical resistance of "β-Ni(OH) 2", is attributed to the semiconducting nature of the material. The electrochemical properties of "β-Ni(OH) 2" in KOH electrolyte are examined by cyclic voltammetric (CV) measurements. The scan-rate dependent voltammograms demonstrate pseudocapacitive behaviour when "β-Ni(OH) 2" is employed as a working electrode in a three-electrode electrochemical cell containing 2 M KOH electrolyte with a platinum counter electrode and a saturated calomel reference electrodes. A specific capacitance of ∼398 × 10 3 F kg -1 is obtained.

Exploration of Gas Discharges with GaAs, GaP and ZnSe Electrodes Under Atmospheric Pressure

NASA Astrophysics Data System (ADS)

Kurt, H. Hilal

2018-03-01

This work reports on the electrical and optical characterization of the atmospheric pressure glow discharge regimes for different semiconductor electrodes made of GaAs, GaP and ZnSe. The discharge cell is driven by DC feeding voltages at a wide pressure range of 0.66-120 kPa in argon and air media for different interelectrode gaps. The discharge phenomena including different stages of discharges such as glow and Townsend breakdown have been examined. In addition, the infrared sensitivities of the semiconducting materials are evaluated in the micro-discharge cell and discharge light emission measurements have been performed. The qualities of the semiconducting electrode samples can be determined by seeking the homogeneity of the discharge light emission for the optoelectronic device applications. Operation of optical devices under atmospheric pressures gives certain advantages for manufacturing of the devices including the material processing and surface treatment procedures. Besides, finite element analyses of the overall experimental system have been performed for the abovementioned semiconductors. The electron densities and potential patterns have been determined on the discharge cell plane between the electrodes. The findings have proven that the electron densities along the plasma cell depend on both the semiconductor type and plasma parameters.

Enhancing pseudocapacitive charge storage in polymer templated mesoporous materials.

PubMed

Rauda, Iris E; Augustyn, Veronica; Dunn, Bruce; Tolbert, Sarah H

2013-05-21

Growing global energy demands coupled with environmental concerns have increased the need for renewable energy sources. For intermittent renewable sources like solar and wind to become available on demand will require the use of energy storage devices. Batteries and supercapacitors, also known as electrochemical capacitors (ECs), represent the most widely used energy storage devices. Supercapacitors are frequently overlooked as an energy storage technology, however, despite the fact that these devices provide greater power, much faster response times, and longer cycle life than batteries. Their limitation is that the energy density of ECs is significantly lower than that of batteries, and this has limited their potential applications. This Account reviews our recent work on improving pseudocapacitive energy storage performance by tailoring the electrode architecture. We report our studies of mesoporous transition metal oxide architectures that store charge through surface or near-surface redox reactions, a phenomenon termed pseudocapacitance. The faradaic nature of pseudocapacitance leads to significant increases in energy density and thus represents an exciting future direction for ECs. We show that both the choice of material and electrode architecture is important for producing the ideal pseudocapacitor device. Here we first briefly review the current state of electrode architectures for pseudocapacitors, from slurry electrodes to carbon/metal oxide composites. We then describe the synthesis of mesoporous films made with amphiphilic diblock copolymer templating agents, specifically those optimized for pseudocapacitive charge storage. These include films synthesized from nanoparticle building blocks and films made from traditional battery materials. In the case of more traditional battery materials, we focus on using flexible architectures to minimize the strain associated with lithium intercalation, that is, the accumulation of lithium ions or atoms between the layers of cathode or anode materials that occurs as batteries charge and discharge. Electrochemical analysis of these mesoporous films allows for a detailed understanding of the origin of charge storage by separating capacitive contributions from traditional diffusion-controlled intercalation processes. We also discuss methods to separate the two contributions to capacitance: double-layer capacitance and pseudocapacitance. Understanding these contributions should allow the selection of materials with an optimized architecture that maximize the contribution from pseudocapacitance. From our studies, we show that nanocrystal-based nanoporous materials offer an architecture optimized for high levels of redox or surface pseudocapacitance. Interestingly, in some cases, materials engineered to minimize the strain associated with lithium insertion can also show intercalation pseudocapacitance, which is a process where insertion processes become so kinetically facile that they appear capacitive. Finally, we conclude with a summary of simple design rules that should result in high-power, high-energy-density electrode architectures. These design rules include assembling small, nanosized building blocks to maximize electrode surface area; maintaining an interconnected, open mesoporosity to facilitate solvent diffusion; seeking flexibility in electrode structure to facilitate volume expansion during lithium insertion; optimizing crystalline domain size and orientation; and creating effective electron transport pathways.

Tailoring gas-phase CO2 electroreduction selectivity to hydrocarbons at Cu nanoparticles

NASA Astrophysics Data System (ADS)

Merino-Garcia, I.; Albo, J.; Irabien, A.

2018-01-01

Copper-based surfaces appear as the most active catalysts for CO2 electroreduction to hydrocarbons, even though formation rates and efficiencies still need to be improved. The aim of the present work is to evaluate the continuous gas-phase CO2 electroreduction to hydrocarbons (i.e. ethylene and methane) at copper nanoparticulated-based surfaces, paying attention to particle size influence (ranging from 25-80 nm) on reaction productivity, selectivity, and Faraday efficiency (FE) for CO2 conversion. The effect of the current density and the presence of a microporous layer within the working electrode are then evaluated. Copper-based gas diffusion electrodes are prepared by airbrushing the catalytic ink onto carbon supports, which are then coupled to a cation exchange membrane (Nafion) in a membrane electrode assembly. The results show that the use of smaller copper nanoparticles (25 nm) leads to a higher ethylene production (1148 μmol m-2 s-1) with a remarkable high FE (92.8%), at the same time, diminishing the competitive hydrogen evolution reaction in terms of FE. This work demonstrates the importance of nanoparticle size on reaction selectivity, which may be of help to design enhanced electrocatalytic materials for CO2 valorization to hydrocarbons.

Electrochemical Detection of the Molecules of Life

NASA Technical Reports Server (NTRS)

Thomson, Seamus; Quinn, Richard; Koehne, Jessica

2017-01-01

All forms of life on Earth contain cellular machinery that can transform and regulate chemical energy through metabolic pathways. These processes are oxidation-reduction reactions that are performed by four key classes of molecules: flavins, nicotinamaides, porphyrins, and quinones. By detecting the electrochemical interaction of these redox-active molecules with an electrode, a method of differentiating them by their class could be established and incorporated into future life-detecting missions. This body of work investigates the electrochemistry of ubiquitous molecules found in life and how they may be detected. Molecules can oxidise or reduce the surface of an electrode - giving or receiving electrons - and these interactions are represented by changes in current with respect to an applied voltage. This relationship varies with: electrolyte type and concentration, working electrode material, the redox-active molecule itself, and scan rate. Flavin adenine dinucleotide (FAD), riboflavin, nicotinamide adenine dinucleotide (NADH), and anthraquinone are all molecules found intracellularly in almost all living organisms. An organism-synthesised extracellular redox-active molecule, Plumbagin, was also selected as part of this study. The goal of this work is to detect these molecules in seawater and assess its application in searching for life on Ocean Worlds.

Synchrotron x-ray diffraction studies of the structural properties of electrode materials in operating battery cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thurston, T.R.; Jisrawi, N.M.; Mukerjee, S.

Hard x rays from a synchrotron source were utilized in diffraction experiments which probed the bulk of electrode materials while they were operating {ital in} {ital situ} in battery cells. Two technologically relevant electrode materials were examined; an {ital AB}{sub 2}-type anode in a nickel{endash}metal{endash}hydride cell and a LiMn{sub 2}O{sub 4} cathode in a Li-ion {open_quote}{open_quote}rocking chair{close_quote}{close_quote} cell. Structural features such as lattice expansions and contractions, phase transitions, and the formation of multiple phases were easily observed as either hydrogen or lithium was electrochemically intercalated in and out of the electrode materials. The relevance of this technique for future studiesmore » of battery electrode materials is discussed. {copyright} {ital 1996 American Institute of Physics.}« less

Carbon materials modified by plasma treatment as electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Lota, Grzegorz; Tyczkowski, Jacek; Kapica, Ryszard; Lota, Katarzyna; Frackowiak, Elzbieta

The carbon material was modified by RF plasma with various reactive gases: O 2, Ar and CO 2. Physicochemical properties of the final carbon products were characterized using different techniques such as gas adsorption method and XPS. Plasma modified materials enriched in oxygen functionalities were investigated as electrodes for supercapacitors in acidic medium. The electrochemical measurements have been carried out using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy. The electrochemical measurements have confirmed that capacity characteristics are closely connected with a type of plasma exposition. Modification processes have an influence on the kind and amount of surface functional groups in the carbon matrix. The moderate increase of capacity of carbon materials modified by plasma has been observed using symmetric two-electrode systems. Whereas investigations made in three-electrode system proved that the suitable selection of plasma modification parameters allows to obtain promising negative and positive electrode materials for supercapacitor application.