Science.gov

Sample records for electrode negative dans

  1. Negative electrode composition

    DOEpatents

    Kaun, Thomas D.; Chilenskas, Albert A.

    1982-01-01

    A secondary electrochemical cell and a negative electrode composition for use therewith comprising a positive electrode containing an active material of a chalcogen or a transiton metal chalcogenide, a negative electrode containing a lithium-aluminum alloy and an amount of a ternary alloy sufficient to provide at least about 5 percent overcharge capacity relative to a negative electrode solely of the lithium-aluminum alloy, the ternary alloy comprising lithium, aluminum, and iron or cobalt, and an electrolyte containing lithium ions in contact with both of the positive and the negative electrodes. The ternary alloy is present in the electrode in the range of from about 5 percent to about 50 percent by weight of the electrode composition and may include lithium-aluminum-nickel alloy in combination with either the ternary iron or cobalt alloys. A plurality of series connected cells having overcharge capacity can be equalized on the discharge side without expensive electrical equipment.

  2. Electrochemical cell and negative electrode therefor

    DOEpatents

    Kaun, Thomas D.

    1982-01-01

    A secondary electrochemical cell with the positive and negative electrodes separated by a molten salt electrolyte with the negative electrode comprising a particulate mixture of lithium-aluminum alloy and electrolyte and an additive selected from graphitized carbon, Raney iron or mixtures thereof. The lithium-aluminum alloy is present in the range of from about 45 to about 80 percent by volume of the negative electrode, and the electrolyte is present in an amount not less than about 10 percent by volume of the negative electrode. The additive of graphitized carbon is present in the range of from about 1 to about 10 percent by volume of the negative electrode, and the Raney iron additive is present in the range of from about 3 to about 10 percent by volume of the negative electrode.

  3. Negative electrodes for lithium cells and batteries

    DOEpatents

    Vaughey, John T.; Fransson, Linda M.; Thackeray, Michael M.

    2005-02-15

    A negative electrode is disclosed for a non-aqueous electrochemical cell. The electrode has an intermetallic compound as its basic structural unit with the formula M.sub.2 M' in which M and M' are selected from two or more metal elements including Si, and the M.sub.2 M' structure is a Cu.sub.2 Sb-type structure. Preferably M is Cu, Mn and/or Li, and M' is Sb. Also disclosed is a non-aqueous electrochemical cell having a negative electrode of the type described, an electrolyte and a positive electrode. A plurality of cells may be arranged to form a battery.

  4. 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.

  5. Negative Electrodes for Li-Ion Batteries

    SciTech Connect

    Kinoshita, Kim; Zaghib, Karim

    2001-10-01

    Graphitized carbons have played a key role in the successful commercialization of Li-ion batteries. The physicochemical properties of carbon cover a wide range; therefore identifying the optimum active electrode material can be time consuming. The significant physical properties of negative electrodes for Li-ion batteries are summarized, and the relationship of these properties to their electrochemical performance in nonaqueous electrolytes, are discussed in this paper.

  6. Negative Electrode For An Alkaline Cell

    DOEpatents

    Coco, Isabelle; Cocciantelli, Jean-Michel; Villenave, Jean-Jacques

    1998-07-14

    The present invention concerns a negative electrode for an alkaline cell, comprising a current collector supporting a paste containing an electrochemically active material and a binder, characterized in that said binder is a polymer containing hydrophilic and hydrophobic groups, said polymer being selected from an acrylic homopolymer, copolymer and terpolymer, an unsaturated organic acid copolymer and an unsaturated acid anhydride copolymer.

  7. Anodes - Materials for negative electrodes in electrochemical energy technology

    NASA Astrophysics Data System (ADS)

    Holze, Rudolf

    2014-06-01

    The basic concepts of electrodes and electrochemical cells (including both galvanic and electrolytic ones) are introduced and illustrated with practical examples. Particular attention is paid to negative electrodes in primary and secondary cells, fuel cell electrodes and electrodes in redox flow batteries. General features and arguments pertaining to selection, optimization and further development are highlighted.

  8. Redox battery including a bromine positive electrode and a chromium ion negative electrode and method

    SciTech Connect

    Giner, J.D.; Stark, H.H.

    1984-09-04

    A redox flow battery with a positive half-cell compartment containing bromide ion, bromine and a complexing organic liquid for bromine, and a negative electrode half-cell compartment containing chromium ion, and including electrolyte fluid communication therebetween.

  9. Low-bias negative differential conductance controlled by electrode separation

    NASA Astrophysics Data System (ADS)

    Yi, Xiao-Hua; Liu, Ran; Bi, Jun-Jie; Jiao, Yang; Wang, Chuan-Kui; Li, Zong-Liang

    2016-12-01

    The electronic transport properties of a single thiolated arylethynylene molecule with 9,10-dihydroanthracene core, denoted as TADHA, is studied by using non-equilibrium Green’s function formalism combined with ab initio calculations. The numerical results show that the TADHA molecule exhibits excellent negative differential conductance (NDC) behavior at lower bias regime as probed experimentally. The NDC behavior of TADHA molecule originates from the Stark effect of the applied bias voltage, by which the highest occupied molecular orbital (HOMO) and the HOMO-1 are pulled apart and become localized. The NDC behavior of TADHA molecular system is tunable by changing the electrode distance. Shortening the electrode separation can enhance the NDC effect which is attributed to the possible increase of coupling between the two branches of TADHA molecule. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374195 and 11405098) and the Natural Science Foundation of Shandong Province, China (Grant No. ZR2013FM006).

  10. Lithium aluminum/iron sulfide battery having lithium aluminum and silicon as negative electrode

    DOEpatents

    Gilbert, Marian; Kaun, Thomas D.

    1984-01-01

    A method of making a negative electrode, the electrode made thereby and a secondary electrochemical cell using the electrode. Silicon powder is mixed with powdered electroactive material, such as the lithium-aluminum eutectic, to provide an improved electrode and cell.

  11. Effect due to plasma electrode adsorbates upon the negative ion current and electron current extracted from a negative ion source

    NASA Astrophysics Data System (ADS)

    Bacal, M.; Wada, M.

    2017-08-01

    The intensity of negative hydrogen (H-) ion current and that of electron current extracted from a negative ion source show different characteristics against the change in plasma electrode bias depending upon the material covering the plasma electrode surface. The knowledge of these characteristics is of importance for a proper design of an efficient H- ion source. This paper discusses this subject based upon two kind of experiments i) experiments with plasma electrodes covered with tungsten or tantalum evaporated from filaments made of these metals ii) experiments with caesium covered plasma electrode. The tantalum and caesium covered plasma electrodes lead to an enhancement of the extracted H- ion current by a factor of 2 compared to the tungsten coverage on the plasma electrode. The electron current is also affected by the material covering the plasma electrode. The reasons for observing these characteristics are also elucidated.

  12. Intermetallic compounds as negative electrodes of Ni/MH batteries

    NASA Astrophysics Data System (ADS)

    Cuevas, F.; Joubert, J.-M.; Latroche, M.; Percheron-Guégan, A.

    2001-04-01

    This review is devoted to the main families of thermodynamically stable intermetallic compounds (AB5-, AB2- and AB-type alloys) that have been researched in the last thirty years as materials for negative electrodes in nickel-metal hydride batteries. The crystal structure of these compounds and their hydrides is widely described. Their solid-gas hydrogenation properties and, particularly, the related desorption isotherm curves are examined as a useful criterion for the selection of suitable battery materials. The electrochemical performances obtained with these alloys are reported and the given solutions to common problems such as corrosion, passivation, decrepitation and short cycle life are discussed. Only AB5-based compounds have achieved, up to now, enough development for being widely present on the market, and exhibit improved battery performances in comparison with the polluting Ni/Cd batteries. The high capacity of AB2-based compounds and the remarkable electrochemical activity of some AB-based alloys make, however, further research on all the reviewed families still valuable.

  13. Intermetallic negative electrodes for non-aqueous lithium cells and batteries

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Johnson, Christopher S.; Fransson, Linda M.; Edstrom, Ester Kristina; Henriksen, Gary

    2004-05-04

    A method of operating an electrochemical cell is disclosed. The cell has an intermetallic negative electrode of Cu.sub.6-x M.sub.x Sn.sub.5, wherein x is .ltoreq.3 and M is one or more metals including Si and a positive electrode containing Li in which Li is shuttled between the positive electrode and the negative electrode during charge and discharge to form a lithiated intermetallic negative electrode during charge. The voltage of the electrochemical cell is controlled during the charge portion of the charge-discharge cycles so that the potential of the lithiated intermetallic negative electrode in the fully charged electrochemical cell is less than 0.2 V but greater than 0 V versus metallic lithium.

  14. Lithium ion battery cells under abusive discharge conditions: Electrode potential development and interactions between positive and negative electrode

    NASA Astrophysics Data System (ADS)

    Kasnatscheew, Johannes; Börner, Markus; Streipert, Benjamin; Meister, Paul; Wagner, Ralf; Cekic Laskovic, Isidora; Winter, Martin

    2017-09-01

    Increasing specific energy of lithium ion battery cells (LIBs) and their cycle life requires deeper understanding of complex processes taking place during the cell operation. This work focuses on the electrode potential development and the interactions between negative and positive electrode in a quasi LIB full cell by applying over-discharge conditions. By analysis of the potential profiles, a characteristic potential plateau at ≈ 3.56 V vs. Li/Li+ was detected at the graphite negative electrode, which can be assigned to the Cu oxidation process of the negative electrode current collector. Also at the positive electrode, a time shifted potential plateau was observed, which could be attributed to a competitive reaction between conventional discharge (lithiation) and parasitic Cu reduction (plating) on the positive electrode surface. The proposed mechanism involving the presence of elemental Cu on the positive electrode surface was confirmed by SEM-EDX mapping experiments. The relevance of Cu dissolution and deposition as well as possible solution approaches are discussed.

  15. Negative-Electrode Catalysts for Fe/Cr Redox Cells

    NASA Technical Reports Server (NTRS)

    Gahn, R. F.; Hagedorn, N.

    1987-01-01

    Electrodes perform more consistently and less expensive. Surfaces catalyzed by bismuth and bismuth/lead developed for application on chromium electrode in iron/chromium redox electrochemical energy storage system. NASA Fe/Cr storage system incorporates two soluble electrodes consisting of acidified solutions of iron chloride (FeC13 and FeC12) and chromium chloride (CrC13 and CrC12) oxidized and reduced in power-conversion unit to store and produce electricity. Electrolytes circulated with pumps and stored in external tanks.

  16. High voltage, rechargeable lithium batteries using newly-developed carbon for negative electrode material

    NASA Astrophysics Data System (ADS)

    Yamaura, Junichi; Ozaki, Yoshiyuki; Morita, Akiyoshi; Ohta, Akira

    1993-03-01

    Carbon is a good candidate for negative electrodes because it can take the form of lithium intercalation compounds. We discussed the characteristics of typical carbon materials which have been studied as negative electrode materials. We have found that the mesophase pitch-based carbon microbead (MCMB) of high graphitization stage which have been graphitized at a high temperature such as 2800 C gives good characteristics as a negative electrode for rechargeable lithium batteries. The cylindrical 'AA-size' batteries of our trial products using LiCoO2 as the positive electrode and the M CMB graphitized at 2800 C as the negative electrode have been found to provide large capacities of 500 mA h and high voltages of 3.7 V with high energy densities of 240 W h/l, 100 W h/kg.

  17. Design of interpenetrated network MWCNT/poly(1,5-DAN) on interdigital electrode: toward NO2 gas sensing.

    PubMed

    Nguyen, Dzung Tuan; Nguyen, My Thanh; Ho, Giang Truong; Nguyen, Toan Ngoc; Reisberg, S; Piro, B; Pham, M C

    2013-10-15

    In this paper, poly(1,5-diaminonaphthalene) was interpenetrated into the network made of multiwalled carbon nanotubes (MWCNT) on platinum interdigital electrode (IDE) by electro-polymerization of 1,5-diaminonaphthalene (1,5-DAN). The electro-polymerization process of 1,5-DAN on MWCNT was controlled by scanning the cyclic voltage at 50 mV s(-1) scan rate between -0.1 V and +0.95 V vs. saturated calomel electrode (SCE). The results of voltammetric responses and Raman spectroscopy represented that the films MWCNT/poly(1,5-DAN) were successfully created by this polymerization process. The films MWCNT/poly(1,5-DAN) were investigated for gas-sensing to NO2 at low concentration level. The gas-sensing results showed that the response-recovery times were long and strongly affected by thickness of the film MWCNT/poly(1,5-DAN). Nevertheless, these films represented auspicious results for gas sensors operating at room temperature.

  18. Method of preparing a negative electrode including lithium alloy for use within a secondary electrochemical cell

    DOEpatents

    Tomczuk, Zygmunt; Olszanski, Theodore W.; Battles, James E.

    1977-03-08

    A negative electrode that includes a lithium alloy as active material is prepared by briefly submerging a porous, electrically conductive substrate within a melt of the alloy. Prior to solidification, excess melt can be removed by vibrating or otherwise manipulating the filled substrate to expose interstitial surfaces. Electrodes of such as solid lithium-aluminum filled within a substrate of metal foam are provided.

  19. High performance lithium insertion negative electrode materials for electrochemical devices

    NASA Astrophysics Data System (ADS)

    Channu, V. S. Reddy; Rambabu, B.; Kumari, Kusum; Kalluru, Rajmohan R.; Holze, Rudolf

    2016-11-01

    Spinel LiCrTiO4 oxides to be used as electrode materials for a lithium ion battery and an asymmetric supercapacitor were synthesized using a soft-chemical method with and without chelating agents followed by calcination at 700 °C for 10 h. Structural and morphological properties were studied with powder X-ray diffraction, scanning electron and transmission electron microscopy. Particles of 50-10 nm in size are observed in the microscopic images. The presence of Cr and Ti is confirmed from the EDS spectrum. Electrochemical properties of LiCrTiO4 electrode were examined in a lithium ion battery. The electrode prepared with oxalic acid-assisted LiCrTiO4 shows higher specific capacity.This LiCrTiO4 is also used as anode material for an asymmetric hybrid supercapacitor. The cell exhibits a specific capacity of 65 mAh/g at 1 mA/cm2. The specific capacity decreases with increasing current densities.

  20. Electrode Engineering of Conversion-based Negative Electrodes for Na-ion Batteries.

    PubMed

    Vogt, Leonie O; Marino, Cyril; Villevieille, Claire

    2015-01-01

    Due to lower costs and higher abundance of sodium, Na-ion battery technology can offer a good alternative to Li-ion batteries. Much research is focusing on developing new cathode and anode materials but the importance of the electrode engineering on the electrochemical performance is often neglected. The electrode composition is especially crucial for conversion reaction-based materials where the composite electrode (active material, conducting additive and binder) has to buffer the huge volume change occurring upon cycling. This work highlights the differences observed on Sn-CMC electrode performance by using different Sn particle sizes (micro- and nanoparticles) and evaluating the role of the conductive additive in the electrode. Carbon fibers (VGCF) demonstrate a good ability to surround micrometer particles but not especially nanometer particles leading to an improvement in the performance of microparticles but not of nanoparticles. For a high loading electrode suitable for full cell applications (>3.5 mg/cm(2) of active material), nanometer particles show limited performance for long-term cycling. The combination of VGCF with micrometer particles seems to be the most promising composition to obtain good performances for conversion reaction based-materials.

  1. Tungsten oxide@polypyrrole core-shell nanowire arrays as novel negative electrodes for asymmetric supercapacitors.

    PubMed

    Wang, Fengmei; Zhan, Xueying; Cheng, Zhongzhou; Wang, Zhenxing; Wang, Qisheng; Xu, Kai; Safdar, Muhammad; He, Jun

    2015-02-11

    Among active pseudocapacitive materials, polypyrrole (PPy) is a promising electrode material in electrochemical capacitors. PPy-based materials research has thus far focused on its electrochemical performance as a positive electrode rather than as a negative electrode for asymmetric supercapacitors (ASCs). Here high-performance electrochemical supercapacitors are designed with tungsten oxide@PPy (WO3 @PPy) core-shell nanowire arrays and Co(OH)2 nanowires grown on carbon fibers. The WO3 @PPy core-shell nanowire electrode exhibits a high capacitance (253 mF/cm2) in negative potentials (-1.0-0.0 V). The ASCs packaged with CF-Co(OH)2 as a positive electrode and CF-WO3 @PPy as a negative electrode display a high volumetric capacitance up to 2.865 F/cm3 based on volume of the device, an energy density of 1.02 mWh/cm3 , and very good stability performance. These findings promote the application of PPy-based nanostructures as advanced negative electrodes for ASCs.

  2. A negative working potential supercapacitor electrode consisting of a continuous nanoporous Fe-Ni network

    NASA Astrophysics Data System (ADS)

    Xie, Yunsong; Chen, Yunpeng; Zhou, Yang; Unruh, Karl M.; Xiao, John Q.

    2016-06-01

    A new class of electrochemical electrodes operating in a negative voltage window has been developed by sintering chemically prepared Fe-Ni nanoparticles into a porous nanoscale mixture of an Fe-rich BCC Fe(Ni) phase and a Ni-rich FCC Fe-Ni phase. The selective conversion of the Fe-rich phase to hydroxides provides the electrochemically active component of the electrodes while the Ni-rich phase provides high conductivity and structural stability. The compositionally optimized electrodes exhibit a specific capacitance in excess of 350 F g-1 (all normalizations are to the total electrode mass rather than the much smaller electrochemically active mass) and retain more than 85% of their maximum specific capacitance after 2000 charging/discharging cycles. In addition to their inexpensive constituents, these electrodes are self-supporting and their thickness and mass loading density of about 65 μm and 20 mg cm-2 are compatible with the established manufacturing processes. This desirable combination of physical and electrochemical properties suggests that these electrodes may be useful as the negative electrode in high performance asymmetric supercapacitors.A new class of electrochemical electrodes operating in a negative voltage window has been developed by sintering chemically prepared Fe-Ni nanoparticles into a porous nanoscale mixture of an Fe-rich BCC Fe(Ni) phase and a Ni-rich FCC Fe-Ni phase. The selective conversion of the Fe-rich phase to hydroxides provides the electrochemically active component of the electrodes while the Ni-rich phase provides high conductivity and structural stability. The compositionally optimized electrodes exhibit a specific capacitance in excess of 350 F g-1 (all normalizations are to the total electrode mass rather than the much smaller electrochemically active mass) and retain more than 85% of their maximum specific capacitance after 2000 charging/discharging cycles. In addition to their inexpensive constituents, these electrodes are

  3. Thermodynamic analysis and effect of crystallinity for silicon monoxide negative electrode for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Yasuda, Kouji; Kashitani, Yusuke; Kizaki, Shingo; Takeshita, Kohki; Fujita, Takehisa; Shimosaki, Shinji

    2016-10-01

    The electrochemical behavior of SiO negative electrodes for lithium ion batteries is thermodynamically and experimentally investigated. The analysis of the reaction pathway and the calculation of the reaction potentials during the Li insertion/extraction reactions are carried out by the construction of the ternary phase diagram for the Li-Si-O system. In the initial reaction of Li insertion, metallic Si and lithium silicates are formed above 0.37 V vs. Li/Li+ as a conversion reaction of the SiO negative electrode. Further Li insertion produces Li-Si alloys as reversible reaction phases. The decomposition of the Li4SiO4 phase begins before the formation of the Li-Si alloy is completed. The measured electrode behavior of the SiO negative electrode basically agrees with the thermodynamic calculations, especially at a low reaction rate; deviations can be ascribed to kinetic factors and electrode resistance. The values of over 1898 mA h g-1 and 71.0% were obtained for the discharge capacity and the coulombic efficiency, respectively. Furthermore, the overvoltage for an amorphous SiO electrode was smaller than that for a disproportionated SiO electrode into Si and SiO2 phases.

  4. Enhanced surface production in H{sup -} ion sources by introducing a negatively biased secondary electrode

    SciTech Connect

    An, Young Hwa; Jung, Bong Ki; Hwang, Y. S.

    2010-02-15

    A transformer coupled plasma negative hydrogen ion source with an external rf antenna has been developed at SNU, which is capable of continuous operation with long lifetime. A positively biased plasma electrode (PE) has been successfully used for the optimization of H{sup -} extraction. With molybdenum-coated stainless steel PE, the enhancement of H{sup -} production at the electrode surface was observed at the bias voltage lower than the plasma potential. However, the low bias voltage is unfavorable to H{sup -} beam extraction since the negative ions are repelled. A second electrode is inserted in front of the PE to enhance H{sup -} production at the electrode surface without impeding beam extraction. By biasing the secondary electrode (SE) more negatively, H{sup -} production is clearly enhanced although the SE itself reduces H{sup -} beam currents because of suppressed electron transport in front of the PE. In this configuration enhancement of surface productions is most pronounced in tantalum electrode among various electrode materials.

  5. Actively cooled plasma electrode for long pulse operations in a cesium-seeded negative ion source

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yukio; Watanabe, Kazuhiro; Okumura, Yoshikazu; Trainham, Rusty; Jacquot, Claude

    2005-01-01

    An actively cooled plasma electrode has been developed for long pulse operation in a cesium-seeded negative ion source. To keep the electrode temperature at about 300°C, which is the optimum range of temperature to enhance cesium effects, the electrode cooling structure has been designed using three-dimensional numerical simulation assuming that the heat flux from the source plasma was 15W/cm2. Water cooling tubes were brazed to the plasma electrode substrate with spacers made of stainless steel, which acts as a thermal resistance. The fabricated plasma electrode has been tested in a cesium-seeded volume negative ion source called Kamaboko source. The temperature of the electrode reached 280°C for the arc power of 41kW, which is the operating condition required for producing D- beams with current densities exceeding 20mA/cm2. It was demonstrated that the actively cooled plasma electrode is applicable to long pulse operations, meeting the temperature requirement for optimizing the surface-production process of negative ions in the cesium-seeded ion source.

  6. Involvement of flocculin in negative potential-applied ITO electrode adhesion of yeast cells

    PubMed Central

    Koyama, Sumihiro; Tsubouchi, Taishi; Usui, Keiko; Uematsu, Katsuyuki; Tame, Akihiro; Nogi, Yuichi; Ohta, Yukari; Hatada, Yuji; Kato, Chiaki; Miwa, Tetsuya; Toyofuku, Takashi; Nagahama, Takehiko; Konishi, Masaaki; Nagano, Yuriko; Abe, Fumiyoshi

    2015-01-01

    The purpose of this study was to develop novel methods for attachment and cultivation of specifically positioned single yeast cells on a microelectrode surface with the application of a weak electrical potential. Saccharomyces cerevisiae diploid strains attached to an indium tin oxide/glass (ITO) electrode to which a negative potential between −0.2 and −0.4 V vs. Ag/AgCl was applied, while they did not adhere to a gallium-doped zinc oxide/glass electrode surface. The yeast cells attached to the negative potential-applied ITO electrodes showed normal cell proliferation. We found that the flocculin FLO10 gene-disrupted diploid BY4743 mutant strain (flo10Δ /flo10Δ) almost completely lost the ability to adhere to the negative potential-applied ITO electrode. Our results indicate that the mechanisms of diploid BY4743 S. cerevisiae adhesion involve interaction between the negative potential-applied ITO electrode and the Flo10 protein on the cell wall surface. A combination of micropatterning techniques of living single yeast cell on the ITO electrode and omics technologies holds potential of novel, highly parallelized, microchip-based single-cell analysis that will contribute to new screening concepts and applications. PMID:26187908

  7. Method of preparing a negative electrode including lithium alloy for use within a secondary electrochemical cell

    DOEpatents

    Tomczuk, Z.; Olszanski, W.; Battles, J.E.

    1975-12-09

    A negative electrode that includes a lithium alloy as active material is prepared by briefly submerging a porous, electrically conductive substrate within a melt of the alloy. Prior to solidification, excess melt can be removed by vibrating or otherwise manipulating the filled substrate to expose interstitial surfaces. Electrodes of such a solid lithium--aluminum filled within a substrate of metal foam are provided. 1 figure, 1 table.

  8. Negative Differential Resistance in ZnO Nanowires Bridging Two Metallic Electrodes

    PubMed Central

    2010-01-01

    The electrical transport through nanoscale contacts of ZnO nanowires bridging the interdigitated Au electrodes shows the negative differential resistance (NDR) effect. The NDR peaks strongly depend on the starting sweep voltage. The origin of NDR through nanoscale contacts between ZnO nanowires and metal electrodes is the electron charging and discharging of the parasitic capacitor due to the weak contact, rather than the conventional resonant tunneling mechanism. PMID:20730121

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

    SciTech Connect

    Xiao, Xingcheng; Zhou, Weidong; Kim, Youngnam; Ryu, Ill; Gu, Meng; Wang, Chong M.; Liu, Gao; Liu, Zhongyi; Gao, Huajian

    2015-03-01

    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 at 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.

  10. MgO-templated carbon as a negative electrode material for Na-ion capacitors

    NASA Astrophysics Data System (ADS)

    Kado, Yuya; Soneda, Yasushi

    2016-12-01

    In this study, MgO-templated carbon with different pore structures was investigated as a negative electrode material for Na-ion capacitors. With increasing the Brunauer-Emmett-Teller surface area, the irreversible capacity increased, and the coulombic efficiency of the 1st cycle decreased because of the formation of solid electrolyte interface layers. MgO-templated carbon annealed at 1000 °C exhibited the highest capacity and best rate performance, suggesting that an appropriate balance between surface area and crystallinity is imperative for fast Na-ion storage, attributed to the storage mechanism: combination of non-faradaic electric double-layer capacitance and faradaic Na intercalation in the carbon layers. Finally, a Na-ion capacitor cell using MgO-templated carbon and activated carbon as the negative and positive electrodes, respectively, exhibited an energy density at high power density significantly greater than that exhibited by the cell using a commercial hard carbon negative electrode.

  11. A stable graphite negative electrode for the lithium-sulfur battery.

    PubMed

    Jeschull, Fabian; Brandell, Daniel; Edström, Kristina; Lacey, Matthew J

    2015-12-14

    Efficient, reversible lithium intercalation into graphite in ether-based electrolytes is enabled through a protective electrode binder, polyacrylic acid sodium salt (PAA-Na). In turn, this enables the creation of a stable "lithium-ion-sulfur" cell, using a lithiated graphite negative electrode with a sulfur positive electrode, using the common DME:DOL solvent system suited to the electrochemistry of the lithium-sulfur battery. Graphite-sulfur lithium-ion cells show average coulombic efficiencies of ∼99.5%, compared with <95% for lithium-sulfur cells, and significantly better capacity retention, taking into account cell balancing considerations. The high efficiency derives from the considerably better interfacial stability of the graphite electrode, which suppresses the polysulfide redox shuttle and self-discharge.

  12. Numerical modelling of needle-grid electrodes for negative surface corona charging system

    NASA Astrophysics Data System (ADS)

    Zhuang, Y.; Chen, G.; Rotaru, M.

    2011-08-01

    Surface potential decay measurement is a simple and low cost tool to examine electrical properties of insulation materials. During the corona charging stage, a needle-grid electrodes system is often used to achieve uniform charge distribution on the surface of the sample. In this paper, a model using COMSOL Multiphysics has been developed to simulate the gas discharge. A well-known hydrodynamic drift-diffusion model was used. The model consists of a set of continuity equations accounting for the movement, generation and loss of charge carriers (electrons, positive and negative ions) coupled with Poisson's equation to take into account the effect of space and surface charges on the electric field. Four models with the grid electrode in different positions and several mesh sizes are compared with a model that only has the needle electrode. The results for impulse current and surface charge density on the sample clearly show the effect of the extra grid electrode with various positions.

  13. Unusual Passivation Ability of Superconcentrated Electrolytes toward Hard Carbon Negative Electrodes in Sodium-Ion Batteries.

    PubMed

    Takada, Koji; Yamada, Yuki; Watanabe, Eriko; Wang, Jianhui; Sodeyama, Keitaro; Tateyama, Yoshitaka; Hirata, Kazuhisa; Kawase, Takeo; Yamada, Atsuo

    2017-10-04

    The passivation of negative electrodes is key to achieving prolonged charge-discharge cycling with Na-ion batteries. Here, we report the unusual passivation ability of superconcentrated Na-salt electrolytes. For example, a 50 mol % sodium bis(fluorosulfonyl)amide (NaFSA)/succinonitrile (SN) electrolyte enables highly reversible Na(+) insertion into a hard carbon negative electrode without any electrolyte additive, functional binder, or electrode pretreatment. Importantly, an anion-derived passivation film is formed via preferential reduction of the anion upon charging, which can effectively suppress further electrolyte reduction. As a structural characteristic of the electrolyte, most anions are coordinated to multiple Na(+) cations at high concentration, which shifts the lowest unoccupied molecular orbitals of the anions downward, resulting in preferential anion reduction. The present work provides a new understanding of the passivation mechanism with respect to the coordination state of the anion.

  14. Graphite felt modified with bismuth nanoparticles as negative electrode in a vanadium redox flow battery.

    PubMed

    Suárez, David J; González, Zoraida; Blanco, Clara; Granda, Marcos; Menéndez, Rosa; Santamaría, Ricardo

    2014-03-01

    A graphite felt decorated with bismuth nanoparticles was studied as negative electrode in a vanadium redox flow battery (VRFB). The results confirm the excellent electrochemical performance of the bismuth modified electrode in terms of the reversibility of the V(3+) /V(2+) redox reactions and its long-term cycling performance. Moreover a mechanism that explains the role that Bi nanoparticles play in the redox reactions in this negative half-cell is proposed. Bi nanoparticles favor the formation of BiHx , an intermediate that reduces V(3+) to V(2+) and, therefore, inhibits the competitive irreversible reaction of hydrogen formation (responsible for the commonly observed loss of Coulombic efficiency of VRFBs). Thus, the total charge consumed during the cathodic sweep in this electrode is used to reduce V(3+) to V(2+) , resulting in a highly reversible and efficient process.

  15. Engineering study on TiSnSb-based composite negative electrode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Wilhelm, H. A.; Marino, C.; Darwiche, A.; Soudan, P.; Morcrette, M.; Monconduit, L.; Lestriez, B.

    2015-01-01

    Micrometric TiSnSb is a promising negative electrode material for Li-ion batteries when formulated with carboxymethyl cellulose (CMC) binder and a mixture of carbon black and carbon nanofibers, and cycled in a fluoroethylene carbonate (FEC)-containing electrolyte. Here, other binder systems were evaluated, polyacrylic acid (PAAH) mixed with CMC, CMC in buffered solution at pH 3 and amylopectin. However CMC showed the better performance in terms of cycle life of the electrode. Whatever the binder, cycle life decreases with increasing the active mass loading, which is attributed to both the precipitation of liquid electrolyte degradation products and to the loss of electrical contacts within the composite electrode and with the current collector as a consequence of the active particles volume variations. Furthermore, calendaring the electrode unfortunately decreases the cycle life. The rate performance was studied as a function of the active mass loading and was shown to be determined by the electrode polarization resistance. Finally, full cells cycling tests with Li1Ni1/3Co1/3Mn1/3O2 at the positive electrode were done. 60% of the capacity is retained after 200 cycles at the surface capacity of 2.7 mAh cm-2.

  16. Review on α-Fe2O3 based negative electrode for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Nithya, V. D.; Arul, N. Sabari

    2016-09-01

    Supercapacitor is an electrochemical energy storage device which has drawn attention of the researchers in recent years due to its high power density and long cycle life. Recently, an enormous effort has been imposed to improve the energy density of supercapacitor and might be attained through asymmetric cell configuration that offer wider potential window. Until now, a significant advancement has been achieved in the fabrication of positive electrodes for asymmetric cell. Nevertheless, the electrochemical performance of negative electrode materials is less explored, especially Hematite (α-Fe2O3). The α-Fe2O3 has been proved to be a promising negative electrode in supercapacitor application due to its wide operating potential, high redox activity, low cost, abundant availability and eco-friendliness. In this review, we have chosen α-Fe2O3 as the negative electrode and discussed its latest research progress with emphasis on various surface engineering synthesis strategies such as, carbon, polymer, metal-metal oxide, and ternary based α-Fe2O3 composites for supercapacitor. Besides, the importance of their synergistic effects over the supercapacitive performance in terms of specific capacitance, energy density, power density, cycling life and rate capability are highlighted. Also, an extensive analysis of the literature about its symmetric/asymmetric cell performance is explored.

  17. Improvement of electrochemical characteristics of natural graphite negative electrode coated with polyacrylic acid in pure propylene carbonate electrolyte

    NASA Astrophysics Data System (ADS)

    Ui, Koichi; Kikuchi, Shinei; Mikami, Fuminobu; Kadoma, Yoshihiro; Kumagai, Naoaki

    In order to improve the negative electrode characteristics of a graphite electrode in a propylene carbonate (PC)-containing electrolyte, we have prepared a graphite negative electrode coated with a water-soluble anionic polymer as a binder for composite graphite electrodes. The electrochemical characteristics of the coated graphite were evaluated by cyclic voltammetry and charge-discharge cycle tests. The coated graphite negative electrode showed a stable Li + ion intercalation/deintercalation reaction without the exfoliation of the graphene layers caused by the co-intercalation of the PC solvent in the LiClO 4/PC solution. The charge-discharge characteristic of the coated graphite negative electrode in a PC-containing electrolyte was almost the same as that in ethylene carbonate-based electrolyte.

  18. Influence of the active mass particle suspension in electrolyte upon corrosion of negative electrode of a lead-acid battery

    NASA Astrophysics Data System (ADS)

    Kamenev, Yu.; Shtompel, G.; Ostapenko, E.; Leonov, V.

    2014-07-01

    The influence of the suspension of positive active mass particles in the electrolyte on the performance of the negative electrode in a lead-acid battery is studied. A significant increase in the rate of corrosion of the lead electrode is shown when slime particles get in contact with its surface, which may result in the rise of macro-defects on the lugs of the negative electrodes.

  19. Study of the influence of carbon on the negative lead-acid battery electrodes

    NASA Astrophysics Data System (ADS)

    Bača, Petr; Micka, Karel; Křivík, Petr; Tonar, Karel; Tošer, Pavel

    Experiments were made with negative lead-acid battery electrodes doped with different concentrations of powdered carbon. It turned out that the rate of formation decreased with the rising concentration of carbon added into the active material. During accelerated cycling in the PSoC regime, the cycle life showed a maximum at a concentration of carbon near 1%, whereas at lower or higher concentrations the cycle life was profoundly lower. A marked increase of the active mass resistance with the cycle number was recorded at carbon concentrations above 2%. Orientation experiments showed that compression of the lead-acid laboratory cells caused an increase of the cycle life of the negative electrode in the studied regime.

  20. Low energy milling method, low crystallinity alloy, and negative electrode composition

    DOEpatents

    Le, Dihn B; Obrovac, Mark N; Kube, Robert Y; Landucci, James R

    2012-10-16

    A method of making nanostructured alloy particles includes milling a millbase in a pebble mill containing milling media. The millbase comprises: (i) silicon, and (ii) at least one of carbon or a transition metal, and wherein the nanostructured alloy particles are substantially free of crystalline domains greater than 50 nanometers in size. A method of making a negative electrode composition for a lithium ion battery including the nanostructured alloy particles is also disclosed.

  1. Hydridable material for the negative electrode in a nickel-metal hydride storage battery

    DOEpatents

    Knosp, Bernard; Bouet, Jacques; Jordy, Christian; Mimoun, Michel; Gicquel, Daniel

    1997-01-01

    A monophase hydridable material for the negative electrode of a nickel-metal hydride storage battery with a "Lave's phase" structure of hexagonal C14 type (MgZn.sub.2) has the general formula: Zr.sub.1-x Ti.sub.x Ni.sub.a Mn.sub.b Al.sub.c Co.sub.d V.sub.e where ##EQU1##

  2. Phase-separated silicon-tin nanocomposites for high capacity negative electrodes in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Xiao, Xingcheng; Wang, John S.; Liu, Ping; Sachdev, Anil K.; Verbrugge, Mark W.; Haddad, Daad; Balogh, Michael P.

    2012-09-01

    Both silicon and tin have a high specific capacity (3600 mAh g-1 for Li15Si4 and 992 mAh g-1 for Li22Sn5 respectively) and are among the most attractive materials for potential negative electrodes in lithium ion batteries. However, mechanical degradation induced by the large volume expansion during the cycling has limited their practical application. In this work, we developed a new class of Si-Sn nanocomposites with unique phase-separated nanostructure, where the amorphous Si nanoparticles are thermodynamically precipitated out from Si-Sn alloy and embedded within the Sn matrix. The phase separation-induced nanostructure provides the capability to mitigate the mechanical degradation, by preventing the nucleation and propagation of microcracks during lithiation. The nanocomposite electrode exhibits relative high capacity (1400 mAh g-1) and excellent cycling stability with the optimum composition and nanostructure.

  3. Negatively strain-dependent electrical resistance of magnetically arranged nickel composites: application to highly stretchable electrodes and stretchable lighting devices.

    PubMed

    Kim, Sangwoo; Byun, Junghwan; Choi, Seongdae; Kim, Donghyun; Kim, Taehoon; Chung, Seungjun; Hong, Yongtaek

    2014-05-21

    A novel property of the negatively strain-dependent electrical resistance change of nickel conductive composites is presented. The composite shows negatively strain-dependent resistance change when magnetically arranged, while most conductive materials show opposite behavior. This negative dependency is utilized to produce highly stretchable electrodes and to demonstrate a new conceptual resolution-sustainable stretchable lighting/display device.

  4. In situ Raman investigation of electrolyte solutions in the vicinity of graphite negative electrodes.

    PubMed

    Song, Hee-Youb; Fukutsuka, Tomokazu; Miyazaki, Kohei; Abe, Takeshi

    2016-10-05

    The structure of electrolyte solutions plays an important role in the lithium-ion intercalation reaction at graphite negative electrodes. The solvation structure of an electrolyte solution in bulk has been investigated previously. However, the structure of an electrolyte solution at the graphite negative electrode/electrolyte solution interface, where the lithium-ion intercalation reaction occurs is more important. In this study, the structure of electrolyte solutions in the vicinity of a graphite negative electrode was investigated using in situ Raman spectroscopy during the 1st reduction process in 1 mol dm(-3) LiClO4/ethylene carbonate (EC) + diethyl carbonate (DEC) (1 : 1 volume ratio), 1 mol dm(-3) LiCF3SO3/propylene carbonate (PC), and 1 mol dm(-3) LiCF3SO3/PC + tetraethylene glycol dimethyl ether (tetraglyme) (20 : 1 volume ratio). As a result, in the electrolyte solutions in which the lithium-ion intercalation reaction can occur (LiClO4/EC + DEC and LiCF3SO3/PC + tetraglyme), the Raman spectra of free solvent molecules (EC or PC) and anions showed a positive vibrational frequency shift during the co-intercalation reaction, and these shifts returned to their original positions during the lithium-ion intercalation reaction. On the other hand, there is no vibrational frequency shift in LiCF3SO3/PC, an electrolyte in which the lithium-ion intercalation reaction cannot occur. Based on our results, the relationship between the Raman shift and the solid electrolyte interphase (SEI) formation process was discussed.

  5. Manufacturing of industry-relevant silicon negative composite electrodes for lithium ion-cells

    NASA Astrophysics Data System (ADS)

    Nguyen, B. P. N.; Chazelle, S.; Cerbelaud, M.; Porcher, W.; Lestriez, B.

    2014-09-01

    In this paper, Poly (acrylic-co-maleic) acid (PAMA) is used as a dispersant to improve the stability of electrodes slurries for large scale processing of Silicon based negative composite electrode. The stability and homogeneity of the slurries are characterized using different techniques. Sedimentation test, electrical measurement, SEM-EDX observations as well as rheological measurements show that a more homogeneous distribution of carbon black (CB) inside the stack of Si particles is reached with presence of PAMA. However, the amount of PAMA is limited due to the competition in the adsorption of PAMA and Carboxylmethyl cellulose (CMC) at the surface of the CB particles. Upon cycling with capacity limitation, the optimized electrode formulation at lab scale could achieve more than 400 cycles with surface capacity ∼2.5-3.3 mAh cm-2. At the pilot scale, the improvement of adhesion of the tape to the current collector by using Styrene-co-Butadiene rubber copolymer latex (SB) helps to maintain long cycle life while calendaring is detrimental to electrochemical properties.

  6. New Ti3C2 aerogel as promising negative electrode materials for asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Lu; Zhang, Mingyi; Zhang, Xitian; Zhang, Zhiguo

    2017-10-01

    Novel 3D Ti3C2 aerogel has been first synthesized by a simple EDA-assisted self-assembly process. Its inside are channels and pores structure. The interconnected aerogel structure could efficiently restrain restacking of Ti3C2 flakes. Thus, it exhibits a large specific surface area as high as 176.3 m2 g-1. The electrochemical performances have been measured. The Ti3C2 aerogel achieves a quite high areal capacitance of 1012.5 mF cm-2 for the mass loading of 15 mg at a scan rate of 2 mV s-1 in 1 M KOH electrolyte. An asymmetric supercapacitor (ASC) has been assembled by using the Ti3C2 aerogel electrode as the negative electrode and electrospinning carbon nanofiber film as the positive electrode. The device can deliver a high energy density of 120.0 μWh cm-2 and a maximum power density of 26123 μW cm-2. A lamp panel with nineteen red light-emitting diodes has been powered by two ASCs in series.

  7. In situ EC-AFM study of effect of lignin on performance of negative electrodes in lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Ban, I.; Yamaguchi, Y.; Nakayama, Y.; Hirai, N.; Hara, S.

    The effect of lignin, which is an important additive for the negative electrode in lead-acid batteries, is studied on lead electrodes in sulfuric acid by means of potentiostatic transient measurements and in situ electrochemical atomic force microscope (EC-AFM) observations. During oxidation of the electrodes, it is confirmed that the current transition in electrolyte with 20 ppm lignin gives a broad, hill-like curve, while that in electrolyte without lignin is a sharp peak. Nevertheless, there is little difference in electrode capacity in each electrolyte throughout the whole oxidation. In electrolyte with lignin, in situ EC-AFM examination reveals a uniform deposition of lead sulfate crystals after oxidation of the electrode. These results suggest that lignin adsorbs on the electrode surface and promotes uniform diffusion of lead ions near the surface during oxidation.

  8. The effect of asymmetrical electrode form after negative bias illuminated stress in amorphous IGZO thin film transistors

    NASA Astrophysics Data System (ADS)

    Su, Wan-Ching; Chang, Ting-Chang; Liao, Po-Yung; Chen, Yu-Jia; Chen, Bo-Wei; Hsieh, Tien-Yu; Yang, Chung-I.; Huang, Yen-Yu; Chang, Hsi-Ming; Chiang, Shin-Chuan; Chang, Kuan-Chang; Tsai, Tsung-Ming

    2017-03-01

    This paper investigates the degradation behavior of InGaZnO thin film transistors (TFTs) under negative bias illumination stress (NBIS). TFT devices with two different source and drain layouts were exanimated: one having a parallel format electrode and the other with UI format electrode. UI means that source/drain electrodes shapes is defined as a forked-shaped structure. The I-V curve of the parallel electrode exhibited a symmetric degradation under forward and reverse sweeping in the saturation region after 1000 s NBIS. In contrast, the I-V curve of the UI electrode structure under similar conditions was asymmetric. The UI electrode structure also shows a stretch-out phenomenon in its C-V measurement. Finally, this work utilizes the ISE-Technology Computer Aided Design (ISE-TCAD) system simulations, which simulate the electron field and IV curves, to analyze the mechanisms dominating the parallel and UI device degradation behaviors.

  9. Room temperature performance of 4 V aqueous hybrid supercapacitor using multi-layered lithium-doped carbon negative electrode

    NASA Astrophysics Data System (ADS)

    Makino, Sho; Yamamoto, Rie; Sugimoto, Shigeyuki; Sugimoto, Wataru

    2016-09-01

    Water-stable multi-layered lithium-doped carbon (LixC6) negative electrode using poly(ethylene oxide) (PEO)-lithium bis(trifluoromethansulfonyl)imide (LiTFSI) polymer electrolyte containing N-methyl-N-propylpiperidinium bis(trifluoromethansulfonyl)imide (PP13TFSI) ionic liquid was developed. Electrochemical properties at 60 °C of the aqueous hybrid supercapacitor using activated carbon positive electrode and a multi-layered LixC6 negative electrode (LixC6 | PEO-LiTFSI | LTAP) without PP13TFSI exhibited performance similar to that using Li anode (Li | PEO-LiTFSI | LTAP). A drastic decrease in ESR was achieved by the addition of PP13TFSI to PEO-LiTFSI, allowing room temperature operation. The ESR of the multi-layered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI at 25 °C was 801 Ω cm2, which is 1/6 the value of the multi-layered Li negative electrode with PEO-LiTFSI (5014 Ω cm2). Charge/discharge test of the aqueous hybrid supercapacitor using multi-layered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI at 25 °C afforded specific capacity of 20.6 mAh (g-activated carbon)-1 with a working voltage of 2.7-3.7 V, and good long-term capability up to 3000 cycles. Furthermore, an aqueous hybrid supercapacitor consisting of a high capacitance RuO2 nanosheet positive electrode and multi-layered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI showed specific capacity of 196 mAh (g-RuO2)-1 and specific energy of 625 Wh (kg-RuO2)-1 in 2.0 M acetic acid-lithium acetate buffered solution at 25 °C.

  10. Surface-modified Mg{sub 2}Ni-type negative electrode materials for Ni-MH battery

    SciTech Connect

    Cui, N.; Luan, B.; Bradhurst, D.; Liu, H.K.; Dou, S.X.

    1997-12-01

    In order to further improve the electrode performance of Mg{sub 1.9}Y{sub 0.1}Ni{sub 0.9}Al{sub 0.1} alloy at ambient temperature, its surface was modified by an ultrasound pretreatment in the alkaline solution and microencapsulation with Ni-P coating. The effects of various surface modifications on the microstructure and electrochemical performance of the alloy electrodes were investigated and compared in this paper. It was found that the modification with ultrasound pretreatment significantly improved the electrocatalytic activity of the negative electrode and then reduced the overpotential of charging/discharging, resulting in a remarkable increase of electrode capacity and high-rate discharge capability but having little influence on the cycle life. However, the electrode fabricated from the microencapsulated alloy powder showed a higher discharge capacity, better high-rate discharge capability and longer cycle life as well.

  11. Modeling of the Plasma Electrode Bias in the Negative Ion Sources with 1D PIC Method

    SciTech Connect

    Matsushita, D.; Kuppel, S.; Hatayama, A.; Fukano, A.; Bacal, M.

    2009-03-12

    The effect of the plasma electrode bias voltage in the negative ion sources is modeled and investigated with one-dimensional plasma simulation. A particle-in-cell (PIC) method is applied to simulate the motion of charged particles in their self-consistent electric field. In the simulation, the electron current density is fixed to produce the bias voltage. The tendency of current-voltage characteristics obtained in the simulation show agreement with the one obtained from a simple probe theory. In addition, the H{sup -} ion density peak appears at the bias voltage close to the plasma potential as observed in the experiment. The physical mechanism of this peak H{sup -} ion density is discussed.

  12. Method for the continuous fabrication of hydrogen storage alloy negative electrodes

    SciTech Connect

    Wolff, M.; Nuss, M.A.; Fetcenko, M.A.; Lijoi, A.L.

    1989-04-11

    A method is described for substantially continuously fabricating a large area, metal hydride electrochemical hydrogen storage alloy negative electrode for use in a rechargeable nickel-metal hydride battery, the method comprising the steps of: providing a continuous, wire mesh screen substrate; providing a measured amount of powdered metal hydride electrochemical hydrogen storage alloy material; continuously disposing a layer of the hydrogen storage alloy material into contact with the wire mesh screen substrate, in a substantially inert atmosphere; compacting the hydrogen storage alloy material into the wire mesh screen so as to form a green deposit thereof; pre-heating the green deposit of hydrogen storage alloy wire mesh screen; sintering the green deposit of hydrogen storage alloy wire mesh screen in an anhydrous, substantially oxygen free inert atmosphere so as to liberate moisture therefrom; and cooling the sintered hydrogen stage alloy wire mesh screen in a controlled hydrogen atmosphere so as to impart a partial charge thereto.

  13. Metal hydrides used as negative electrode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Sartori, Sabrina; Cuevas, Fermin; Latroche, Michel

    2016-02-01

    Energy is a key issue for future generation. Researches are conducted worldwide to develop new efficient means for energy conversion and storage. Electrochemical storage is foreseen as an efficient way to handle intermittent renewable energy production. The most advanced batteries are nowadays based on lithium-ion technology though their specific capacities should be significantly increased to bring solution to mass storage. Conversion reactions are one way to step forward larger capacities at the anode. We here review the possibility to use metallic or complex hydrides as negative electrode using conversion reaction of hydride with lithium. Moreover, promising alloying of lithium with the metallic species might provide additional reversible capacities. Both binary and ternary systems are reviewed and results are compared in the frame of the electrochemical application.

  14. Nano-composite Si particle formation by plasma spraying for negative electrode of Li ion batteries

    NASA Astrophysics Data System (ADS)

    Kambara, M.; Kitayama, A.; Homma, K.; Hideshima, T.; Kaga, M.; Sheem, K.-Y.; Ishida, S.; Yoshida, T.

    2014-04-01

    Nano-composite silicon powders have been produced at a maximum process throughput of 6 g/min by plasma spraying with metallurgical grade silicon powder as raw material. The obtained powders are found to be fundamentally composed of crystalline silicon particles of 20-40 nm in diameter, and are coated with an ˜5-nm-thick amorphous carbonous layer when methane gas is additionally introduced during plasma spraying. The performance of half-cell batteries containing the powders as negative electrodes has shown that the capacity decay observed for the raw Si coarse particles is significantly improved by plasma treatment. The carbonous coating potentially contributes to an improvement in capacity retention, although coexisting SiC particles that inevitably form during high-temperature processing reduce the overall capacity.

  15. Silicon micropowder negative electrode endures more than 1000 cycles when a surface-roughened clad current collector is used

    NASA Astrophysics Data System (ADS)

    Kataoka, Riki; Oda, Yoshimitsu; Inoue, Ryouji; Kawasaki, Norioki; Takeichi, Nobuhiko; Kiyobayashi, Tetsu

    2017-04-01

    A surface-roughened clad (S-clad) current collector significantly extends the cycle-life of the lithium ion negative electrode composed of a silicon micropowder and an aqueous binder. The high tensile strength of the S-clad is also proved to be important for improving the battery performance of the electrode by comparison to a surface-roughened pure Cu current collector. Moreover, adding 10 vol.% fluoroethylene carbonate to the electrolyte further extends the cycle-life of the Si electrode. The synergic effect of the high adhesive and tensile strength of the S-clad current collector as well as the electrolyte additive results in maintaining the reversible capacity of 1000 mA h g-1 for more than 1000 cycles, in which 1.0-1.2 mg cm-2 of the active material is loaded on the electrode.

  16. Electrochemical performance of Na2Ti3O7/C negative electrode in ionic liquid electrolyte for sodium secondary batteries

    NASA Astrophysics Data System (ADS)

    Ding, Changsheng; Nohira, Toshiyuki; Hagiwara, Rika

    2017-06-01

    In this study, carbon-coated Na2Ti3O7 (Na2Ti3O7/C) is synthesized by a solid-state reaction method, and its charge-discharge characteristics as a negative electrode material in an ionic liquid electrolyte, Na[FSA]-[C3C1pyrr][FSA] (FSA = bis(fluorosulfonyl)amide; C3C1pyrr = N-methyl-N-propylpyrrolidinium), are investigated at 363 K. The Na2Ti3O7/C negative electrode shows an initial discharge capacity of 215 mAh (g-Na2Ti3O7/C)-1 at a current rate of 20 mA (g-Na2Ti3O7/C)-1 in the voltage range 0.01-2.5 V. The high discharge capacity of the Na2Ti3O7/C negative electrode is attributed to the high operation temperature in the Na[FSA]-[C3C1pyrr][FSA] ionic liquid electrolyte. Although high discharge capacity is achieved, the Na2Ti3O7/C negative electrode shows relatively poor cycle performance because of the irreversible insertion of some Na ions and the formation of cracks.

  17. Electrode

    SciTech Connect

    Clere, T.M.

    1983-08-30

    A 3-dimensional electrode is disclosed having substantially coplanar and substantially flat portions and ribbon-like curved portions, said curved portions being symmetrical and alternating in rows above and below said substantially coplanar, substantially flat portions, respectively, and a geometric configuration presenting in one sectional aspect the appearance of a series of ribbon-like oblate spheroids interrupted by said flat portions and in another sectional aspect, 90/sup 0/ from said one aspect, the appearance of a square wave pattern.

  18. Corrosion behavior of surface treated steel in liquid sodium negative electrode of liquid metal battery

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghyeon; Shin, Sang Hun; Lee, Jung Ki; Choi, Sungyeol; Kim, Ji Hyun

    2016-03-01

    While liquid metal batteries are attractive options for grid-scale energy storage applications as they have flexible siting capacities and small footprints, the compatibility between structural materials such as current collectors and negative electrode such as sodium is one of major issues for liquid metal batteries. Non-metallic elements such as carbon, oxygen, and nitrogen in the liquid sodium influence the material behaviors of the cell construction materials in the battery system. In this study, the compatibility of structural materials with sodium is investigated in high temperature liquid sodium, and electrochemical impedance spectroscopy (EIS) is used to monitor in-situ the corrosion behavior at the surface of materials in sodium. Chemical vapor deposition (CVD) coatings of SiC and Si3N4 are applied as protective barriers against dissolution and corrosion on the steel surface. The results show that CVD coating of Si compounds can delay corrosion of steel in high temperature liquid sodium comparing to the result of as-received specimens, while SiC coating is more durable than Si3N4 coating in high temperature liquid sodium.

  19. Rationalizing thermal reactions of C6Lix negative electrode with nonaqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Mukai, Kazuhiko; Inoue, Takao; Hasegawa, Madoka

    2017-10-01

    Exothermic reactions at elevated temperatures (T) between Li-intercalated C6Lix negative electrodes and nonaqueous electrolytes play a crucial role in the thermal runaway of lithium-ion batteries. However, despite intensive studies so far, the origin of the reactions has not been fully understood, particularly from the viewpoint of a material balance. In this paper, we performed differential scanning calorimetry (DSC) analyses up to 450 °C for samples with x = 0.22, 0.45, 0.67, and 0.89, which were prepared from a graphited mesophase-pitch-based carbon fiber. The DSC profiles for C6Lix with 1 M LiPF6 dissolved in ethylene carbonate (EC)/diethylene carbonate (DEC) solution (EC/DEC = 3/7 by volume) were found to be divided into four different T regions regardless of x. That is, Region (I) below 150 °C, Region (II) for 150 °C < T ≤ 240 °C, Region (III) for 240 °C < T ≤ 270 °C, and Region (IV) above 270 °C. By combining with results for X-ray diffraction measurements and scanning electron microscopic analyses, we have rationalized the change in enthalpy (ΔH) of each Region taking into account the given material balance. Strategies for inhibiting the thermal runaway of LIBs are also discussed.

  20. CuSbS2 as a negative electrode material for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Marino, C.; Block, T.; Pöttgen, R.; Villevieille, C.

    2017-02-01

    CuSbS2 was tested as a negative electrode material for sodium-ion batteries. The material synthesized by ball milling offers a specific charge of 730 mAh g-1, close to the theoretical value (751 mAh g-1), over a few cycles. The reaction mechanism was investigated by means of operando X-ray diffraction, 121Sb Mössbauer spectroscopy, and Cu K-edge X-ray absorption spectroscopy. These studies reveal a sodiation mechanism that involves an original conversion reaction in two steps, through the formation of a ternary phase, CuSb(1-x)S(2-y), as well as a NaxS alloy and Sb, followed by an alloying reaction involving the previously formed Sb. The desodiation process ends with the reformation of the ternary phase, CuSb(1-x‧)S(2-y‧), deficient in Sb and S; this phase is responsible for the good reversibility observed upon cycling.

  1. Sodium titanate nanotubes as negative electrode materials for sodium-ion capacitors.

    PubMed

    Yin, Jiao; Qi, Li; Wang, Hongyu

    2012-05-01

    The lithium-based energy storage technology is currently being considered for electric automotive industry and even electric grid storage. However, the hungry demand for vast energy sources in the modern society will conflict with the shortage of lithium resources on the earth. The first alternative choice may be sodium-related materials. Herein, we propose an electric energy storage system (sodium-ion capacitor) based on porous carbon and sodium titanate nanotubes (Na-TNT, Na(+)-insertion compounds) as positive and negative electrode materials, respectively, in conjunction with Na(+)-containing non-aqueous electrolytes. As a low-voltage (0.1-2 V) sodium insertion nanomaterial, Na-TNT was synthesized via a simple hydrothermal reaction. Compared with bulk sodium titanate, the predominance of Na-TNT is the excellent rate performance, which exactly caters to the need for electrochemical capacitors. The sodium-ion capacitors exhibited desirable energy density and power density (34 Wh kg(-1), 889 W kg(-1)). Furthermore, the sodium-ion capacitors had long cycling life (1000 cycles) and high coulombic efficiency (≈ 98 % after the second cycle). More importantly, the conception of sodium-ion capacitor has been put forward.

  2. Hybrid supercapacitor devices based on MnCo2O4 as the positive electrode and FeMn2O4 as the negative electrode

    NASA Astrophysics Data System (ADS)

    Nagamuthu, Sadayappan; Vijayakumar, Subbukalai; Lee, Seong-Hun; Ryu, Kwang-Sun

    2016-12-01

    MnCo2O4 nanosheets and FeMn2O4 nanospheres were synthesized using a hydrothermal method. Choline chloride was used as the capping agent during the preparation of the nanoparticles. XRD patterns confirmed the spinel structure of MnCo2O4 and FeMn2O4. XPS measurements were used to determine the oxidation state of the prepared spinel metal oxides. HRTEM images revealed the formation of hexagonal nanosheets of MnCo2O4 and nanospheres of FeMn2O4. Electrochemical measurements were made for both positive and negative electrodes using three electrode systems. MnCo2O4 Exhibits 282C g-1 and FeMn2O4 yields 110C g-1 at a specific current of 1 A g-1. Hybrid supercapacitor device was fabricated using MnCo2O4 as the positive and FeMn2O4 as the negative electrode material. The hybrid supercapacitor device was delivered a maximum power of 37.57 kW kg-1.

  3. Evidence of Negative Capacitance in Piezoelectric ZnO Thin Films Sputtered on Interdigital Electrodes.

    PubMed

    Laurenti, Marco; Verna, Alessio; Chiolerio, Alessandro

    2015-11-11

    The scaling paradigm known as Moore's Law, with the shrinking of transistors and their doubling on a chip every two years, is going to reach a painful end. Another less-known paradigm, the so-called Koomey's Law, stating that the computing efficiency doubles every 1.57 years, poses other important challenges, since the efficiency of rechargeable energy sources is substantially constant, and any other evolution is based on device architecture only. How can we still increase the computational power/reduce the power consumption of our electronic environments? A first answer to this question comes from the quest for new functionalities. Within this aim, negative capacitance (NC) is becoming one of the most intriguing and studied phenomena since it can be exploited for reducing the aforementioned limiting effects in the downscaling of electronic devices. Here we report the evidence of negative capacitance in 80 nm thick ZnO thin films sputtered on Au interdigital electrodes (IDEs). Highly (002)-oriented ZnO thin films, with a fine-grained surface nanostructure and the desired chemical composition, are deposited at room temperature on different IDEs structures. Direct-current electrical measurements highlighted the semiconducting nature of ZnO (current density in the order of 1 × 10(-3) A/cm(2)). When turned into the alternating current regime (from 20 Hz to 2 MHz) the presence of NC values is observed in the low-frequency range (20-120 Hz). The loss of metal/semiconductor interface charge states under forward bias conditions, together with the presence of oxygen vacancies and piezoelectric/electrostriction effects, is believed to be at the basis of the observed negative behavior, suggesting that ZnO thin-film-based field-effect transistors can be a powerful instrument to go beyond the Boltzmann limit and the downscaling of integrated circuit elements required for the fabrication of portable and miniaturized electronic devices, especially for electric household

  4. Controllable Negative Differential Resistance Behavior of an Azobenzene Molecular Device Induced by Different Molecule-Electrode Distances

    NASA Astrophysics Data System (ADS)

    Fan, Zhi-Qiang; Zhang, Zhen-Hua; Qiu, Ming; Deng, Xiao-Qing; Tang, Gui-Ping

    2012-07-01

    We report the ab initio calculations of transport behaviors of an azobenzene molecular device which is similar to the experimental configurations. The calculated results show that the transport behaviors of the device are sensitive to the molecule-electrode distance and the currents will drop rapidly when the molecule-electrode distance changes from 1.7 Å to 2.0 Å. More interestingly, the negative differential resistance behavior can be found in our device. Nevertheless, it is not the inherent property of an azobenzene molecular device but an effect of the molecule-electrode distance. Detailed analyses of the molecular projected self-consistent Hamiltonian states and the transmission spectra of the system reveal the physical mechanism of these behaviors.

  5. Si–Cu alloy nanowires grown by oblique angle deposition as a stable negative electrode for Li-ion batteries

    SciTech Connect

    Polat, B. D.; Keles, O.; Chen, Z. H.; Amine, K.

    2016-03-29

    Thin films having nanocolumnar arrays made of various Si–Cu atomic ratios (90–10, 80–20, 70–30 %) are fabricated by an ion-assisted oblique angle co-deposition technique to produce stable negative electrodes for lithium-ion batteries. Cu is added into the electrode because of its ductility and electron conductivity. Cu plays a crucial role in holding the electrode together, minimizing overall capacity loss and enabling faster electron transfer. Plus, Cu is inactive versus Li?; therefore, Si–Cu variation is expected to affect the electrochemical performances of the electrodes. In this work, the effect of Si–Cu atomic ratios on the morphologies and the structures of the electrodes are studied. Plus, the uses of these nanocolumns with different Cu contents are evaluated as anodes by electrochemical tests. The morphological analyses demonstrate that an increase in Si–Cu atomic ratio affects the width of the nanocolumns and the homogeneity of the thin film morphology. The increase in Cu content dramatically improves the capacity retention of Si–Cu anodes, whereas it decreases the initial discharge capacity.

  6. Li-Metal-Free Prelithiation of Si-Based Negative Electrodes for Full Li-Ion Batteries.

    PubMed

    Zhou, Haitao; Wang, Xuehang; Chen, De

    2015-08-24

    Most of the high-capacity positive-electrode materials [for example, S, O2 (air), and MOx (M: V, Mn, Fe, etc.)] are Li-deficient and require the use of a Li-metal electrode or prelithiation. Herein, we report a novel electrolytic cell in which the Si electrode can be prelithiated in a well-controlled manner from Li-containing aqueous solution in a Li-metal-free way. MnOx/Si and S/Si Li-ion full cells were assembled by using the prelithiated Si negative electrodes, which resulted in high specific energies of 349 and 732 Wh kg(-1), respectively. The MnOx/Si full cell still retains 138 Wh kg(-1) even at a high specific power of 1710 W kg(-1). This is the first report of a whole process of making a full Li-ion battery with both Li-deficient electrodes without the use of Li metal as the Li source. This novel prelithiation process, with high controllability, no short circuiting, and an abundant Li source, is expected to contribute significantly to the development of safe, green, and powerful Li-ion batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Charge-discharge characteristics of all-solid-state thin-filmed lithium-ion batteries using amorphous Nb 2O 5 negative electrodes

    NASA Astrophysics Data System (ADS)

    Nakazawa, Hiromi; Sano, Kimihiro; Abe, Takashi; Baba, Mamoru; Kumagai, Naoaki

    All-solid-state thin-filmed lithium-ion rechargeable batteries composed of amorphous Nb 2O 5 negative electrode with the thickness of 50-300 nm and amorphous Li 2Mn 2O 4 positive electrode with a constant thickness of 200 nm, and amorphous Li 3PO 4- xN x electrolyte (100 nm thickness), have been fabricated on glass substrates with a 50 mm × 50 mm size by a sputtering method, and their electrochemical characteristics were investigated. The charge-discharge capacity based on the volume of positive electrode increased with increasing thickness of negative electrode, reaching about 600 mAh cm -3 for the battery with the negative electrode thickness of 200 nm. But the capacity based on the volume of both the positive and negative electrodes was the maximum value of about 310 mAh cm -3 for the battery with the negative electrode thickness of 100 nm. The shape of charge-discharge curve consisted of a two-step for the batteries with the negative electrode thickness more than 200 nm, but that with the thickness of 100 nm was a smooth S-shape curve during 500 cycles.

  8. Improved electrochemical performance of boron-doped SiO negative electrode materials in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Woo, Jihoon; Baek, Seong-Ho; Park, Jung-Soo; Jeong, Young-Min; Kim, Jae Hyun

    2015-12-01

    We introduce a one-step process that consists of thermal disproportionation and impurity doping to enhance the reversible capacity and electrical conductivity of silicon monoxide (SiO)-based negative electrode materials in Li-ion batteries. Transmission electron microscope (TEM) results reveal that thermally treated SiO at 900 °C (H-SiO) consists of uniformly dispersed nano-crystalline Si (nc-Si) in an amorphous silicon oxide (SiOx) matrix. Compared to that of prinstine SiO, the electrochemical performance of H-SiO shows improved specific capacity, due mainly to the increased reversible capacity by nc-Si and to the reduced volume expansion by thermally disproportionated SiOx matrix. Further electrochemical improvements can be obtained by boron-doping on SiO (HB-SiO) using solution dopant during thermal disproportionation. HB-SiO electrode without carbon coating exhibits significantly enhanced specific capacity superior to that of undoped H-SiO electrode, having 947 mAh g-1 at 0.5C rate and excellent capacity retention of 93.3% over 100 cycles. Electrochemical impedance spectroscopy (EIS) measurement reveals that the internal resistance of the HB-SiO electrode is significantly reduced by boron doping.

  9. Transition-Metal Carbodiimides as Molecular Negative Electrode Materials for Lithium- and Sodium-Ion Batteries with Excellent Cycling Properties

    SciTech Connect

    Sougrati, Moulay T.; Darwiche, Ali; Liu, Xiaohiu; Mahmoud, Abdelfattah; Hermann, Raphael P.; Jouen, Samuel; Monconduit, Laure; Dronskowski, Richard; Stievano, Lorenzo

    2016-03-16

    Here we report evidence for the electrochemical activity of transition-metal carbodiimides versus lithium and sodium. In particular, iron carbodiimide, FeNCN, can be efficiently used as a negative electrode material for alkali-metal-ion batteries, similar to its oxide analogue FeO. Based on 57Fe M ssbauer and infrared spectroscopy (IR) data, the electrochemical reaction mechanism can be explained by the reversible transformation of the Fe NCN into Li/Na NCN bonds during discharge and charge. These new electrode materials exhibit higher capacity compared to well-established negative electrode references such as graphite or hard carbon. Contrary to its oxide analogue, iron carbodiimide does not require heavy treatments (nanoscale tailoring, sophisticated textures, coating etc.) to obtain long cycle life with density current as high as 9 A/g-1 for hundreds of charge/discharge cycles. Similar to the iron compound, several other transition-metal carbodiimides Mx(NCN)y with M = Mn, Cr, Zn can cycle successfully versus lithium and sodium. Ultimately, their electrochemical activity and performances open the way to the design of a novel family of anode materials.

  10. Transition-Metal Carbodiimides as Molecular Negative Electrode Materials for Lithium- and Sodium-Ion Batteries with Excellent Cycling Properties.

    PubMed

    Sougrati, Moulay T; Darwiche, Ali; Liu, Xiaohiu; Mahmoud, Abdelfattah; Hermann, Raphael P; Jouen, Samuel; Monconduit, Laure; Dronskowski, Richard; Stievano, Lorenzo

    2016-04-11

    We report evidence for the electrochemical activity of transition-metal carbodiimides versus lithium and sodium. In particular, iron carbodiimide, FeNCN, can be efficiently used as negative electrode material for alkali-metal-ion batteries, similar to its oxide analogue FeO. Based on (57)Fe Mössbauer and infrared spectroscopy (IR) data, the electrochemical reaction mechanism can be explained by the reversible transformation of the Fe-NCN into Li/Na-NCN bonds during discharge and charge. These new electrode materials exhibit higher capacity compared to well-established negative electrode references such as graphite or hard carbon. Contrary to its oxide analogue, iron carbodiimide does not require heavy treatments (such as nanoscale tailoring, sophisticated textures, or coating) to obtain long cycle life with current density as high as 9 A g(-1) for hundreds of charge-discharge cycles. Similar to the iron compound, several other transition-metal carbodiimides M(x)(NCN)y with M=Mn, Cr, Zn can cycle successfully versus lithium and sodium. Their electrochemical activity and performance open the way to the design of a novel family of anode materials.

  11. Transition-Metal Carbodiimides as Molecular Negative Electrode Materials for Lithium- and Sodium-Ion Batteries with Excellent Cycling Properties

    DOE PAGES

    Sougrati, Moulay T.; Darwiche, Ali; Liu, Xiaohiu; ...

    2016-03-16

    Here we report evidence for the electrochemical activity of transition-metal carbodiimides versus lithium and sodium. In particular, iron carbodiimide, FeNCN, can be efficiently used as a negative electrode material for alkali-metal-ion batteries, similar to its oxide analogue FeO. Based on 57Fe M ssbauer and infrared spectroscopy (IR) data, the electrochemical reaction mechanism can be explained by the reversible transformation of the Fe NCN into Li/Na NCN bonds during discharge and charge. These new electrode materials exhibit higher capacity compared to well-established negative electrode references such as graphite or hard carbon. Contrary to its oxide analogue, iron carbodiimide does not requiremore » heavy treatments (nanoscale tailoring, sophisticated textures, coating etc.) to obtain long cycle life with density current as high as 9 A/g-1 for hundreds of charge/discharge cycles. Similar to the iron compound, several other transition-metal carbodiimides Mx(NCN)y with M = Mn, Cr, Zn can cycle successfully versus lithium and sodium. Ultimately, their electrochemical activity and performances open the way to the design of a novel family of anode materials.« less

  12. Ultra-fast dry microwave preparation of SnSb used as negative electrode material for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Antitomaso, P.; Fraisse, B.; Sougrati, M. T.; Morato-Lallemand, F.; Biscaglia, S.; Aymé-Perrot, D.; Girard, P.; Monconduit, L.

    2016-09-01

    Tin antimonide alloy was obtained for the first time using a very simple dry microwave route. Up to 1 g of well crystallized SnSb can be easily prepared in 90 s under air in an open crucible. A full characterization by X-ray diffraction and 119Sn Mössbauer spectroscopy demonstrated the benefit of carbon as susceptor, which avoid any oxide contamination. The microwave-prepared SnSb was tested as negative electrode material in Li batteries. Interesting results in terms of capacity and rate capability were obtained with up to 700 mAh/g sustained after 50 cycles at variable current. These results pave the way for the introduction of microwave synthesis as realistic route for a rapid, low cost and up-scalable production of electrode material for Li batteries or other large scale application types.

  13. A structural study of solid electrolyte interface on negative electrode of lithium-Ion battery by electron microscopy.

    PubMed

    Matsushita, Tadashi; Watanabe, Jiro; Nakao, Tatsuya; Yamashita, Seiichi

    2014-11-01

    For the last decades, the performance of the lithium-ion battery (LIB) has been significantly improved and its applications have been expanding rapidly. However, its performance has yet to be enhanced.In the lithium-ion battery development, it is important to elucidate the electrode structure change in detail during the charge and discharge cycling. In particular, solid electrolyte interface (SEI) formed by decomposition of the electrolytes on the graphite negative electrode surface should play an important role for battery properties. Therefore, it is essential to control the structure and composition of SEI to improve the battery performance. Here, we conducted a scanning electron microscope (SEM) and transmission electron microscope (TEM) study to elucidate the structures of the SEI during the charge and discharge process using LiNi1/3Co1/3Mn1/3O2 [1] cathode and graphite anode. [2] Since SEI is a lithium-containing compound with high activity, it was observed without being exposed to the atmosphere. The electrodes including SEI were sampled after dismantling batteries with cutoff voltages of 3V and 4.2V for the charge process and 3V for the discharge process. Fig.1 shows SEM images of the graphite electrode surface during the charge and discharge process. The change of the SEI structure during the process was clearly observed. Further, TEM images showed that the SEI grew thicker during the charge process and becomes thinner when discharged. These results with regard to the reversible SEI structure could give a new insight for the battery development.jmicro;63/suppl_1/i21/DFU056F1F1DFU056F1Fig. 1.SEM images of the graphite electrode surface:(a) before charge process;(b) with charge-cutoff voltage of 3.0V; (c) with charge-cutoff voltage of 4.2V; (d) with discharge-cutoff voltage of 3.0V.

  14. Properties of a carbon negative electrode in completely inorganic thin film Li-ion batteries with a LiCoO{sub 2} positive electrode

    SciTech Connect

    Goldner, R.B.; Slaven, S.; Liu, T.Y.

    1995-10-01

    Completely inorganic thin film lithium ion battery cells have been prepared by vapor deposition processes (vacuum evaporation and sputtering). The negative and positive electrodes were films of disordered carbon and lithium cobalt oxide, respectively. The results of battery charging/discharging and other measurements (e.g., in-situ lithium chemical diffusion constant measurements for the carbon films) indicate that disordered carbon films have a relatively high reversible charge capacity, (> 160 mC/cm{sup 2}-{mu}m, and possibly higher than 360 mC/cm{sup 2}-{mu}m, or > 296 and possibly 667 mAh/g, respectively, assuming the measured film density of 1.5g/cm{sup 3}), and a lithium chemical diffusion constant at room temperature {approximately}10{sup -9} cm{sup 2}/s. These results suggest that disordered carbon films should be good substitutes for metallic lithium in thin film rechargeable batteries.

  15. Reinstating lead for high-loaded efficient negative electrode for rechargeable sodium-ion battery

    NASA Astrophysics Data System (ADS)

    Darwiche, Ali; Dugas, Romain; Fraisse, Bernard; Monconduit, Laure

    2016-02-01

    Due to its weight and toxicity, Pb is usually not considered as possible anode for Li- and Na-ion (NIBs) batteries. Nevertheless the toxicity is related to specific applications and its recycling is more than 99% which is one of the highest recycling rates on the planet where no other power source is utilized in more applications with such sustainability. For this reason, we have investigated micrometric lead particles as electrode for NIBs in an ether-based electrolyte (1 M NaPF6 in diglyme). The cyclability, coulombic efficiency and rate capability of lead were unexpected. A high loaded lead electrode with 98%wt of Pb and only 1% of carbon additive showed i) a capacity retention of 464 mA h/g after 50 cycles with only 1.5% of capacity loss, which represents a high volumetric capacity of 5289 mA h/cm3 due to the high density of Pb and ii) a very interesting capacity retention even at high current rate (1950 mA/g). In situ XRD study confirmed a sodiation-desodiation process in four steps. Preliminary tests in Pb//Na3V2(PO4)2F3 full cells showed promising results demonstrating that Pb could be a practical candidate for future high energy density Na-ion batteries with an efficient sodiated or non sodiated positive electrode.

  16. Negligible "negative space-charge layer effects" at oxide-electrolyte/electrode interfaces of thin-film batteries.

    PubMed

    Haruta, Masakazu; Shiraki, Susumu; Suzuki, Tohru; Kumatani, Akichika; Ohsawa, Takeo; Takagi, Yoshitaka; Shimizu, Ryota; Hitosugi, Taro

    2015-03-11

    In this paper, we report the surprisingly low electrolyte/electrode interface resistance of 8.6 Ω cm(2) observed in thin-film batteries. This value is an order of magnitude smaller than that presented in previous reports on all-solid-state lithium batteries. The value is also smaller than that found in a liquid electrolyte-based batteries. The low interface resistance indicates that the negative space-charge layer effects at the Li3PO(4-x)N(x)/LiCoO2 interface are negligible and demonstrates that it is possible to fabricate all-solid state batteries with faster charging/discharging properties.

  17. Resolving Losses at the Negative Electrode in All-Vanadium Redox Flow Batteries Using Electrochemical Impedance Spectroscopy

    SciTech Connect

    Sun, Che Nan; Delnick, Frank M; Aaron, D; Mench, Matthew M; Zawodzinski, Thomas A

    2014-01-01

    We present an in situ electrochemical technique for the quantitative measurement and resolution of the ohmic, charge transfer and diffusion overvoltages at the negative electrode of an all-vanadium redox flow battery (VRFB) using electrochemical impedance spectroscopy (EIS). The mathematics describing the complex impedance of the V+2/V+3 redox reaction is derived and matches the experimental data. The voltage losses contributed by each process have been resolved and quantified at various flow rates and electrode thicknesses as a function of current density during anodic and cathodic polarization. The diffusion overvoltage was affected strongly by flow rate while the charge transfer and ohmic losses were invariant. On the other hand, adopting a thicker electrode significantly changed both the charge transfer and diffusion losses due to increased surface area. Furthermore, the Tafel plot obtained from the impedance resolved charge transfer overvoltage yielded the geometric exchange current density, anodic and cathodic Tafel slopes (135 5 and 121 5 mV/decade respectively) and corresponding transfer coefficients = 0.45 0.02 and = 0.50 0.02 in an operating cell.

  18. Biomimetic nanostructuring of copper thin films enhances adhesion to the negative electrode laminate in lithium-ion batteries.

    PubMed

    Zheng, Ziyan; Wang, Zhihui; Song, Xiangyun; Xun, Shidi; Battaglia, Vincent; Liu, Gao

    2014-10-01

    Thin films of copper are widely used as current collectors for the negative electrodes in lithium-ion batteries. However, a major cause of battery failure is delamination between the current collector and the graphite anode. When silicon or tin is used as active material, delamination becomes a key issue owing to the large volume changes of these materials during lithation and delithation processes. Learning from Nature, we developed a new biomimetic approach based on the adhesion properties of the feet of geckos. The biomimetic approach improves adhesion between the laminate and the copper surface by introducing an array of Cu(OH)2 nanorods, which increases the surface area of the current collector. When graphite anode laminate is casted onto regular and a modified copper surfaces, the modified current collector displays superior adhesion to graphite and the PVDF binder-based electrode. The electrochemical performance of the batteries using these electrodes is not compromised by the additional chemistry of the Cu(OH)2 on the copper surface. The technique can lead to enhanced battery lifetimes over long-term cycling.

  19. 2LiH + M (M = Mg, Ti): New concept of negative electrode for rechargeable lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Oumellal, Y.; Rougier, A.; Tarascon, J.-M.; Aymard, L.

    xLiH + M composites, where M = Mg or Ti, are suggested as new candidates for negative electrode for Li-ion batteries. For this purpose, the xLiH + M electrode is prepared using the mechanochemical reaction: MH x + xLi → xLiH + M or by simply grinding a xLiH + M mixture. The most promising electrochemical behaviour is obtained with the (2LiH + Mg) composite prepared via a mechanochemical reaction between MgH 2 and metallic Li leading to a very divided composite in which Mg crystallites of 20 nm size are embedded in a LiH matrix. Reversible capacities of 1064 mAh g -1 (three times as much as the one of graphite) and 600 mAh g -1 are reached for these phase mixtures after 1 and 28 h of grinding in vertical and planetary mill, respectively. The (2LiH + Ti) mixture prepared via the mechanochemical reaction between TiH 2 and Li exhibits a reversible capacity of 428 mAh g -1. From X-ray diffraction measurements, the performances of the electrodes are attributed to the electrochemical conversion reaction: M + xLiH ↔ MH x + xLi + + xe - (M = Mg, Ti) followed for M = Mg by an alloying process where M reacts with lithium ions to form Mg 1- xLi x alloys.

  20. Wen-dan decoction improves negative emotions in sleep-deprived rats by regulating orexin-a and leptin expression.

    PubMed

    Wu, Fengzhi; Song, Yuehan; Li, Feng; He, Xin; Ma, Jie; Feng, Ting; Guan, Binghe; Wang, Liye; Li, Sinai; Liu, Xiaolan; Liu, Yan; Mao, Meng; Liu, Jing; Bai, Shijing; Song, Cai

    2014-01-01

    Wen-Dan Decoction (WDD), a formula of traditional Chinese medicine, has been clinically used for treating insomnia for approximately 800 years. However, the therapeutic mechanisms of WDD remain unclear. Orexin-A plays a key role in the sleep-wake cycle, while leptin function is opposite to orexin-A. Thus, orexin-A and leptin may be important factors in sleep disorders. In this study, 48 rats were divided into control, model, WDD-treated, and diazepam-treated groups. The model of insomnia was produced by sleep deprivation (SD) for 14 days. The expressions of orexin-A, leptin, and their receptors in blood serum, prefrontal cortex, and hypothalamus were detected by enzyme-linked immunosorbent assay, immunohistochemistry, and real time PCR. Open field tests showed that SD increased both crossing movement (Cm) and rearing-movement (Rm) times. Orexin-A and leptin levels in blood serum increased after SD but decreased in brain compared to the control group. mRNA expressions of orexin receptor 1 and leptin receptor after SD were decreased in the prefrontal cortex but were increased in hypothalamus. WDD treatment normalized the behavior and upregulated orexin-A, leptin, orexin receptor 1 and leptin receptor in brain. The findings suggest that WDD treatment may regulate SD-induced negative emotions by regulating orexin-A and leptin expression.

  1. A Commercial Conducting Polymer as Both Binder and Conductive Additive for Silicon Nanoparticle-Based Lithium-Ion Battery Negative Electrodes.

    PubMed

    Higgins, Thomas M; Park, Sang-Hoon; King, Paul J; Zhang, Chuanfang John; McEvoy, Niall; Berner, Nina C; Daly, Dermot; Shmeliov, Aleksey; Khan, Umar; Duesberg, Georg; Nicolosi, Valeria; Coleman, Jonathan N

    2016-03-22

    This work describes silicon nanoparticle-based lithium-ion battery negative electrodes where multiple nonactive electrode additives (usually carbon black and an inert polymer binder) are replaced with a single conductive binder, in this case, the conducting polymer PSS. While enabling the production of well-mixed slurry-cast electrodes with high silicon content (up to 95 wt %), this combination eliminates the well-known occurrence of capacity losses due to physical separation of the silicon and traditional inorganic conductive additives during repeated lithiation/delithiation processes. Using an in situ secondary doping treatment of the PSS with small quantities of formic acid, electrodes containing 80 wt % SiNPs can be prepared with electrical conductivity as high as 4.2 S/cm. Even at the relatively high areal loading of 1 mg/cm(2), this system demonstrated a first cycle lithiation capacity of 3685 mA·h/g (based on the SiNP mass) and a first cycle efficiency of ∼78%. After 100 repeated cycles at 1 A/g this electrode was still able to store an impressive 1950 mA·h/g normalized to Si mass (∼75% capacity retention), corresponding to 1542 mA·h/g when the capacity is normalized by the total electrode mass. At the maximum electrode thickness studied (∼1.5 mg/cm(2)), a high areal capacity of 3 mA·h/cm(2) was achieved. Importantly, these electrodes are based on commercially available components and are produced by the standard slurry coating methods required for large-scale electrode production. Hence, the results presented here are highly relevant for the realization of commercial LiB negative electrodes that surpass the performance of current graphite-based negative electrode systems.

  2. Improved electrochemical performance of SnO2-mesoporous carbon hybrid as a negative electrode for lithium ion battery applications.

    PubMed

    Srinivasan, N R; Mitra, Sagar; Bandyopadhyaya, Rajdip

    2014-04-14

    To utilize the high specific capacity of SnO2 as an anode material in lithium-ion batteries, one has to overcome its poor cycling performance and rate capability, which result from large volume expansion (∼300%) of SnO2 during charging-discharging cycles. Hence, to accommodate the volume change during cycling, SnO2 nanoparticles of 6 nm diameter were synthesized specifically only on the outer surface of the mesopores, present within mesoporous carbon (CMK-5) particles, resulting in an effective buffering layer. To that end, the synthesis process first involves the formation of 3.5 nm SnO2 nanoparticles inside the mesopores of mesoporous silica (SBA-15), the latter being used as a template subsequently to obtain SnO2-CMK-5 hybrid particles. SnO2-CMK-5 exhibits superior rate capabilities, e.g. after 30 cycles, a specific discharge capacity of 598 mA h g(-1), at a current density of 178 mA g(-1). Electrochemical impedance spectroscopy reveals that the SnO2-CMK-5 electrode undergoes a significant reduction in solid-electrolyte interfacial and charge transfer resistances, with a simultaneous increase in the diffusion coefficient of lithium ions, all these in comparison to an electrode made of only SnO2 nanoparticles. This enhances the potential of using the SnO2-CMK-5 hybrid as a negative electrode, in terms of improved discharge capacity and cycling stability, compared to other electrodes, such as only SnO2 or only CMK-5.

  3. Electrical discharge occurring between a negatively charged particle cloud and a grounded sphere electrode

    NASA Astrophysics Data System (ADS)

    Higashiyama, Y.; Migita, S.; Toki, K.; Sugimoto, T.

    2008-12-01

    Electrostatic discharge occurring between a space-charge cloud and a grounded object was investigated using a large-scale charged particle cloud formed by using three set of cloud generators consisting of a blower and corona charger. The ejecting velocity of the particles affects the formation of the charged cloud. At the lower velocity, the charged cloud spread due to electrostatic repulsion force, while at the higher velocity cloud forms an elongated conical shape. To cause electrostatic discharge between the cloud and a grounded object, a grounded sphere electrode with 100 mm in diameter was set at the inside or outside of the cloud. The brush-like discharge channels reached the maximum length of 0.55 m. The discharge current has a waveform with single or multi-peak, a current peak of several amperes, the maximum charge quantity of 2 μC, and the duration of several microseconds. The relationship between the charge quantity and the current peak or the duration in each discharge was examined. The discharge between the cloud and the electrode placed at the outside of the cloud has relatively longer channels and multi-peak current with the longer duration, while that at the inside of the cloud has the lower charge quantity with single peak.

  4. Synthesis and properties of Li3VO4 - Carbon composite as negative electrode for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Narumi, Kengo; Mori, Tomoya; Kumasaka, Rei; Tojo, Tomohiro; Inada, Ryoji; Sakurai, Yoji

    2017-07-01

    Lithium vanadate Li3VO4 (LVO) is known to be as one of the attractive candidates for negative electrode of lithium-ion battery (LIB) with high safety. Although theoretical capacity of LVO attains to 400 mAh g-1, the actual charge and discharge capacities are far below due to its low electrical and ionic conductivity. In this study, we synthesized carbon-coated LVO (C-LVO) via one-step solid state reaction method and examined its properties as a negative electrode for LIB. From XRD measurements and SEM observation, crystal structure of C-LVO was nearly identical with non-coated one but grain size of former was much smaller than latter with same annealing temperature, suggesting that introduction of carbon source in starting materials effectively helps to suppress LVO grain growth during annealing. TEM observation of C-LVO also shows that amorphous carbon layer with its thickness of several ten nm was formed on the surface of LVO grain. In electrochemical testing, C-LVO shows much higher charge and discharge capacities than non-coated LVO.

  5. Evaluation and Testing of Commercially-Available Carbon Nanotubes as Negative Electrodes for Lithium Ion Cells

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    2007-01-01

    Rechargeable lithium ion (Li-ion) battery technology offers significant performance advantages over the nickel-based technologies used for energy storage for the majority of NASA's missions. Specifically Li-ion technology offers a threefold to fourfold increase in gravimetric and volumetric energy densities and produces voltages in excess of three times the value of typical nickel-based battery systems. As part of the Advanced Battery Technology program at NASA Glenn Research Center (GRC), a program on the evaluation of anodes for Li-ion cells and batteries was conducted. This study focused on the feasibility of using carbon nanotubes as anodes in Li-Ion cells. Candidate materials from multiple sources were evaluated. Their performance was compared to a standard anode comprised of mesocarbon microbeads. In all cases, the standard MCMB electrode exhibited superior performance. The details and results of the study are presented.

  6. Amorçage d'une décharge dans le vide entre deux electrodes d'argent ou des alliages argent-nickel

    NASA Astrophysics Data System (ADS)

    Zouache, N.; Lefort, A.

    1997-03-01

    Comparison of the characteristics of an electric are breakdown in vacuum between two silver or silver-nickel alloy electrodes prompted us to study the evolution of the breakdown voltage with electrode separation, with resistance value placed between the anode and the high voltage supply used for the breakdown, and with the effect of conditionning by heating in vacuum. The measurement of the commutation time and delay time, and the observations by a metallographic microscope of the electrodes surfaces after one breakdown, enabled us to evidence the origin of the electric arc for each of the studied materials. La comparaison des caractéristiques de l'amorçage d'un arc électrique dans le vide entre deux électrodes bombées de 8mm de diamètre et de rayon de courbure en surface de 16mm, constituées d'argent ou de son alliage avec le nickel, nous a amené à étudier l'évolution de la tension d'amorçage avec plusieurs paramètres : la distance inter-électrodes, les valeurs de la résistance intercalée entre la source haute tension servant au claquage et les électrodes et le conditionnement par chauffage sous vide des électrodes. La mesure du temps de commutation, du temps de retard et les observations au microscope métallographique de la surface des électrodes après un amorçage donnent des informations sur l'origine de l'arc électrique concernant chaque matériau étudié.

  7. A new method to study Li-ion cell safety: laser beam initiated reactions on both charged negative and positive electrodes

    NASA Astrophysics Data System (ADS)

    Pérès, J. P.; Perton, F.; Audry, C.; Biensan, Ph; de Guibert, A.; Blanc, G.; Broussely, M.

    The improvement of Li-ion batteries safety in abuse use is one of the key issues for their establishment in future hybrid or electrical vehicles. Such a challenge requires a perfect understanding of phenomena which could occur in abuse situation. A new technique for a better understanding of Li-ion cell safety has been so investigated. Reactions between electrolyte and charged electrodes (positive and negative just recovered from dismantled charged 4/5A cells) have been initiated by a laser beam, having a monitored intensity and time pulse. From such a device, a strong and controlled heating can be generated, in a very short time scale, on a defined electrode surface area. This localized heating, which is supposed to be similar to that could occur from a cell internal short-circuit, is able to initiate "self-propagation reactions" on charged negative and positive electrodes. This new technique has allowed a ranking of charged electrodes in terms of "self-propagation ability". This range of new data has been compared to results obtained from classical thermal characterization methods (DSC, DTA) and results obtained from normalized abuse tests. Global charged negative and positive electrodes degradation mechanisms have been proposed in good agreement with the whole results. The safety of a done Li-ion cell seems mainly related to active negative and positive active materials, but also to other components of the electrodes, and especially additive carbons and aluminum collector of the positive side.

  8. TiO 2-B nanowires as negative electrodes for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Armstrong, A. Robert; Armstrong, Graham; Canales, Jesus; Bruce, Peter G.

    TiO 2-B nanowires (20-40 nm diameter) may be prepared in high yield by a simple synthetic procedure. Lithium may be intercalated up to Li 0.91TiO 2-B corresponding to a capacity of 305 mAh g -1 and at a potential of 1.6 V versus Li + (1 M)/Li. This can be compared with 160 mAh g -1 for Li 4Ti 5O 12 and 165 mAh g -1 for TiO 2-anatase. Following a small irreversible capacity on the first cycle, capacity retention is excellent corresponding to a fade of <0.1% per cycle at a rate of 50 mA g -1. A capacity of 160 mAh g -1 is sustained at a rate of 500 mA g -1 in electrodes that were not optimised for rate capability. Results to date indicate that the small irreversible loss of capacity on the first cycle is not associated with a SEI layer.

  9. TiO2(B) nanoribbons as negative electrode material for lithium ion batteries with high rate performance.

    PubMed

    Beuvier, Thomas; Richard-Plouet, Mireille; Mancini-Le Granvalet, Maryline; Brousse, Thierry; Crosnier, Olivier; Brohan, Luc

    2010-09-20

    Nanosized TiO(2)(B) has been investigated as a possible candidate to replace Li(4)Ti(5)O(12) or graphite as the negative electrode for a Li-ion battery. Nanoribbon precursors, classically synthesized in autogenous conditions at temperatures higher than 170 °C in alkaline medium, have been obtained, under reflux (T ∼ 120 °C, P = 1 bar). After ionic exchange, these nanoribbons exhibit a surface area of 140 m(2) g(-1), larger than those obtained under autogenous conditions or by solid state chemistry. These nanoparticles transform after annealing to isomorphic titanium dioxide. They mainly crystallize as the TiO(2)(B) variety with only 5% of anatase. This quantification of the anatase/TiO(2)(B) ratio was deduced from Raman spectroscopy measurement. TEM analysis highlights the excellent crystallinity of the nanosized TiO(2)(B), crystallizing as 6 nm thin nanoribbons. These characteristics are essential in lithium batteries for a fast lithium ion solid state diffusion into the active material. In lithium batteries, the TiO(2)(B) nanoribbons exhibit a good capacity and an excellent rate capability (reversible capacity of 200 mA h g(-1) at C/3 rate (111 mA g(-1)), 100 mA h g(-1) at 15C rate (5030 mA g(-1)) for a 50% carbon black loaded electrode). The electrode formulation study highlights the importance of the electronic and ionic connection around the active particles. The cycleability of the nano-TiO(2)(B) is another interesting point with a capacity loss of 5% only, over 500 cycles at 3C.

  10. Dependence of image flickering of negative dielectric anisotropy liquid crystal on the flexoelectric coefficient ratio and the interdigitated electrode structure

    NASA Astrophysics Data System (ADS)

    Lee, Hyojin; Kim, Hyungmin; Kim, Jongyoon; Lee, Ji-Hoon

    2016-02-01

    We experimentally measured the splay (e s) and the bend flexoelectric coefficients (e b) of liquid crystal (LC) mixtures with negative dielectric anisotropy and investigated their effect on the image flicker of the LC mixtures driven with a low frequency electric field. Using the experimentally measured e s and e b, we simulated the transmittance (TR) response with the continuum model. First, we confirmed that the TR simulation results were approximated to the experimental data with only small variation. Second, we varied the simulation parameters of e s , e b, the separation (S), and the width (W) of the interdigitated electrodes and tried to find the optimum condition showing the least image flicker. Given W  =  3.0 μm and e b  =  5.7 pC m-1, it was found that the image flicker could be minimized when the e s /e b value was about 2.4 and the S/W ratio was about 1.5. Because the e s /e b value of the rod-like LC material is generally less than 1, it is desirable to design an interdigitated electrode structure to minimize the image flicker effect.

  11. Electrochemical Study of Hollow Carbon Nanospheres as High-Rate and Low Temperature Negative Electrodes for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Cox, Jonathan David

    The continued advancements in portable electronics have demanded more advanced power sources. To date, lithium ion batteries have been the state-of-the-art for portable devices. One significant drawback of lithium ion batteries is the slow charging times and their performance at low temperatures. In this dissertation, we explore the electrochemical behavior of a new lithium ion, negative electrode active material, hollow carbon nanospheres (HCNS). HCNS are ˜50 nm in diameter hollow spheres with ˜5 - 10 nm graphic walls which have a nominal reversible capacity of ˜220 mAh/g. We assembled and cycled HCNS as a lithium ion anode material and compared it to graphite, currently used as the anode material in most commercial lithium ion batteries. The charging mechanism of HCNS is an intercalation of the lithium ions into the graphitic walls of the spheres, similar to graphite, determined by diffraction and electroanalytical techniques. However, the HCNS electrodes cycled at much higher charge and discharge rates than graphite. Additionally, we demonstrated HCNS cycling at low temperatures (-20 *C) in electrolytes not obtainable by graphite due to material exfoliation during cycling. Although, due to the large surface area of HCNS, the first cycle coulombic losses are very high. This work has resulted in an understanding of a potentially new lithium ion battery anode material with significantly better cycling attributes than the current anode material.

  12. The ternary MnFe2O4/graphene/polyaniline hybrid composite as negative electrode for supercapacitors

    NASA Astrophysics Data System (ADS)

    Sankar, Kalimuthu Vijaya; Selvan, Ramakrishnan Kalai

    2015-02-01

    The ternary MnFe2O4/graphene/polyaniline (PANI) composite was successfully prepared for the negative electrode in hybrid supercapacitors. The MnFe2O4 particles are synthesized by polymer assisted solution combustion method without any high temperature calcinations. Similarly, the flexible graphene and PANI are prepared by eco-friendly hydrothermal and in situ polymerization method, respectively. The presence of possible functional groups and the existence of individual constituents in the composite were identified through Fourier transform infra-red spectra (FT-IR) and Raman spectra. Transmission electron microscope (TEM) image reveals that the MnFe2O4 particles are dispersed on the flexible graphene sheet and are wrapped by PANI. The ternary composite electrode delivered a specific capacitance of 241 F g-1 at 0.5 mA cm-2, which was 7.5 times higher than MnFe2O4. The calculated b-value elucidates that the charge storage mechanism in the ternary system is based on the capacitive behavior rather than intercalation. The increase in ratio between capacitive and intercalation current with respect to scan rate corroborates that the pseudocapacitive charge storage mechanism is dominant. Further, the fabricated hybrid supercapacitor provides the maximum specific capacitance and energy density of 48.5 F g-1 at 0.5 mA cm-2 and 17 Wh kg-1, respectively. In addition, the hybrid supercapacitor exhibits excellent cyclic stability of up to 5000 successive cycles.

  13. Electrochemical modification of a pyrolytic graphite sheet for improved negative electrode performance in the vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Kabir, Humayun; Gyan, Isaiah O.; Francis Cheng, I.

    2017-02-01

    The vanadium redox flow battery is a promising technology for buffering renewable energies. It is recognized that negative electrode is the limitation in this device where there are problems of slow heterogeneous electron transfer (HET) of V3+/2+ and parasitic H2 evolution. Any methods aimed at addressing one of these barriers must assess the effects on the other. We examine electrochemical enhancement of a common commercially available material. Treatment of Panasonic pyrolytic graphite sheets is through oxidation at 2.1 V vs. Ag/AgCl for 1 min in 1 M H2SO4. This increases the standard HET rate for V3+/2+ from 3.2 × 10-7 to 1 × 10-3 cm/s, one of the highest in literature and shifts voltammetric reductive peak potential from -1.0 V to -0.65 V in 50 mM V3+ in 1 M H2SO4. Infrared analysis of the surfaces indicates formation of Csbnd OH, Cdbnd O, and Csbnd O functionalities. These groups catalyze HET with V3+/2+ as hypothesized by Skyllas-Kasacos. Also of significance is that electrode modification decreases the fraction of the current directed towards H2 evolution. This proportion decreases by two orders of a magnitude from 12% to 0.1% as measured at the respective voltammetric peak potentials of -1.0 V (pristine) and -0.65 V (modified).

  14. 119Sn Mössbauer parameters as predictive tool for future Sn-based negative electrode materials

    NASA Astrophysics Data System (ADS)

    Naille, S.; Jumas, J.-C.; Lippens, P.-E.; Olivier-Fourcade, J.

    Thanks to the 119Sn Mössbauer hyperfine parameters, it is possible to analyze and predict Li reaction mechanisms with Sn-based negative electrodes for Li-ion batteries. The present approach is based on the interpretation of the 119Sn Mössbauer hyperfine parameters: isomer shift (δ) and quadrupole splitting (Δ) by considering: (i) the analysis of the 119Sn Mössbauer hyperfine parameters of the Li-Sn alloys used as model compounds, (ii) their interpretation from some physicochemical parameters (Li/Sn ratio, crystal structure, electronic density as defined by Hume-Rothery), and (iii) the proposition of an experimental based model to understand Li lithiation/delithiation mechanisms and predict electrochemical performances for Sn-based compounds including the effects of volume variations, particle coalescence or SEI formation.

  15. Li-rich Li-Si alloy as a lithium-containing negative electrode material towards high energy lithium-ion batteries.

    PubMed

    Iwamura, Shinichiroh; Nishihara, Hirotomo; Ono, Yoshitaka; Morito, Haruhiko; Yamane, Hisanori; Nara, Hiroki; Osaka, Tetsuya; Kyotani, Takashi

    2015-01-28

    Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

  16. Li-Rich Li-Si Alloy As A Lithium-Containing Negative Electrode Material Towards High Energy Lithium-Ion Batteries

    PubMed Central

    Iwamura, Shinichiroh; Nishihara, Hirotomo; Ono, Yoshitaka; Morito, Haruhiko; Yamane, Hisanori; Nara, Hiroki; Osaka, Tetsuya; Kyotani, Takashi

    2015-01-01

    Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell. PMID:25626879

  17. Molybdenum dioxide-anchored graphene foam as a negative electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Mu, Xuemei; Liu, Xiaozhi; Zhang, Ke; Li, Jian; Zhou, Jinyuan; Xie, Erqing; Zhang, Zhenxing

    2016-03-01

    Molybdenum dioxide nanoparticles of diameter 100 nm were anchored uniformly to a three-dimensional (3D) graphene foam using an ultrasonication-assisted deposition method. X-ray diffraction and Raman spectroscopy indicated that the molybdenum dioxide nanoparticles had a monoclinic crystal structure. The 3D graphene/MoO2 nanoparticle composite showed excellent pseudocapacitive ability as its specific capacitance reached 404 F g-1 at a scan rate of 2 mV s-1 in the negative potential range, -1.0 to -0.2 V, in a neutral solution. Overall, the 3D graphene/MoO2 nanoparticle composite has great potential as an anode material for the next generation of high-performance supercapacitors. [Figure not available: see fulltext.

  18. Auditory event-related potentials over medial frontal electrodes express both negative and positive prediction errors.

    PubMed

    Hsu, Yi-Fang; Hämäläinen, Jarmo A; Moutsopoulou, Karolina; Waszak, Florian

    2015-03-01

    While the neuronal activation in the medial frontal cortex is thought to reflect higher-order evaluation processes of reward prediction errors when a reward deviates from our expectation, there is increasing evidence that the medial frontal activity might express prediction errors in general. However, given that several studies examined the medial frontal event-related potentials (ERPs) by comparing signals triggered by different stimuli and different anticipations, it remains an open question whether the medial frontal signals are sensitive to the valence of prediction errors. Here we orthogonally manipulated expectation magnitude (i.e., large/small expectation) and expectation confirmation (i.e., fulfilled/violated expectation) in a target detection task with rewards. We found that the medial frontal ERPs were more negative-going for unexpected outcomes in comparison with expected outcomes, regardless of whether a large/small reward was expected. The result supports the idea that the medial frontal signals express prediction errors in general regardless of their valence. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Charge Kondo effect in negative-U quantum dots with superconducting electrodes

    NASA Astrophysics Data System (ADS)

    Fang, Tie-Feng; Guo, Ai-Min; Lu, Han-Tao; Luo, Hong-Gang; Sun, Qing-Feng

    2017-08-01

    Recent experimental realization of superconducting quantum dot devices with intradot attraction U [Nature (London) 521, 196 (2015), 10.1038/nature14398; Phys. Rev. X 6, 041042 (2016), 10.1103/PhysRevX.6.041042] offers unique opportunities to study the charge Kondo effect in a superconducting environment. In such devices pseudospin flips are caused by two tunneling processes. One is the cotunneling of normal electrons which generates near-gap Kondo resonances in the single-electron spectral density. This negative-U charge Kondo effect is more robust than the conventional spin Kondo effect against the suppression by the superconductivity. The other tunneling is the mean-field Cooper-pair tunneling which produces a zero-energy bound state in the pair spectral density. Interesting crossover physics from the strongly-correlated Kondo screening to the mean-field polarization of local pseudospin is demonstrated. Due to the interplay of these two tunnelings, the supercurrent is suppressed for intermediate couplings, but it can increase to the unitary limits both in the strong and weak coupling regimes. We obtain the magnetic field-dependent supercurrent which is consistent with the key experimental findings.

  20. Tailoring the potential window of negative electrodes: A diagnostic method for understanding parasitic oxidation reactions in cells with 5 V LiNi0.5Mn1.5O4 positive electrodes

    NASA Astrophysics Data System (ADS)

    Levi, Mikhael D.; Dargel, Vadim; Shilina, Yuliya; Borgel, Valentina; Aurbach, Doron; Halalay, Ion C.

    2015-03-01

    We present herein a diagnostic method which provides insights into the interactions between parasitic reactions at battery electrodes and their consequences for battery performance degradation. We also provide a cautionary tale about misinterpreting or misrepresenting the significance of test data, as is sometimes found in the peer-reviewed literature or in developers' claims. Reversible cycling of the LiNi0.5Mn1.5O4 positive electrode in a full cell with an electrolyte solution containing no additives may appear achievable through tailoring of the operating potential window of the cell. Self-discharging of the negative stems from parasitic oxidation products formed on the positive. We show that either excess negative electrode capacity over the positive or initial pre-lithiation of the negative suppresses their detrimental effect on capacity retention. Simultaneous monitoring the potentials of the two electrodes vs. Li/Li+ during galvanostatic cycling of a full cell shows, however, that self-discharging of the negative still takes place. The latter process was tracked by the drift of the average potential of the cell towards higher values and leads to two characteristic patterns in the failure of full cells during their long-term cycling, depending on whether a cut-off voltage or a capacity limit is used as the control criterion during cycling.

  1. Lithium-ion capacitors using carbide-derived carbon as the positive electrode - A comparison of cells with graphite and Li4Ti5O12 as the negative electrode

    NASA Astrophysics Data System (ADS)

    Rauhala, Taina; Leis, Jaan; Kallio, Tanja; Vuorilehto, Kai

    2016-11-01

    The use of carbide-derived carbon (CDC) as the positive electrode material for lithium-ion capacitors (LICs) is investigated. CDC based LIC cells are studied utilizing two different negative electrode materials: graphite and lithium titanate Li4Ti5O12 (LTO). The graphite electrodes are prelithiated before assembling the LICs, and LTO containing cells are studied with and without prelithiation. The rate capability and cycle life stability during 1000 cycles are evaluated by galvanostatic cycling at current densities of 0.4-4 mA cm-2. The CDC shows a specific capacitance of 120 F g-1 in the organic lithium-containing electrolyte, and the LICs demonstrate a good stability over 1000 charge-discharge cycles. The choice of the negative electrode is found to have an effect on the utilization of the CDC positive electrode during cycling and on the specific energy of the device. The graphite/CDC cell delivers a maximum specific discharge energy of 90 Wh kg-1 based on the total mass of active material in the cell. Both the prelithiated and non-prelithiated LTO/CDC cells show a specific energy of around 30 Wh kg-1.

  2. TiO 2(B) as a promising high potential negative electrode for large-size lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Inaba, Minoru; Oba, Yasuyuki; Niina, Fumiharu; Murota, Yosuke; Ogino, Yasuyuki; Tasaka, Akimasa; Hirota, Ken

    Needle-like TiO 2(B) powder was obtained from K 2Ti 4O 9 precursor by ion exchange to protons, followed by dehydration. The charge and discharge characteristics of the TiO 2(B) powder were investigated as a high potential negative electrode in lithium-ion batteries. It had a high discharge capacity of 200-250 mAh g -1 at around 1.6 V vs. Li/Li +, which was comparable with that of TiO 2(B) nanowires and nanotubes prepared via a hydrothermal reaction in alkaline solution. It showed very good cycleability, and gave a discharge capacity of 170 mAh g -1 even in the 650th cycle. It also had a high rate capability, and gave a discharge capacity of 106 mAh g -1 even at 10 °C. In most of ethylene carbonate-based solutions, the TiO 2(B) powder exhibited good charge and discharge characteristics. However, it showed a poor compatibility with LiBF 4, propylene carbonate, and γ-butyrolactone. The TiO 2(B) powder showed good cycle performance in the presence of a non-flammable additive, trimethyl phosphate, up to 20 vol.%, and a high tolerance to water up to 1000 ppm. It was also found that inexpensive Al foil can be used as a current collector of the TiO 2(B) powder instead of Cu foil without sacrificing the performance.

  3. Fabrication of Si negative electrodes for Li-ion batteries (LIBs) using cross-linked polymer binders

    NASA Astrophysics Data System (ADS)

    Jang, Suk-Yong; Han, Sien-Ho

    2016-12-01

    Currently, Si as an active material for LIBs has been attracting much attention due to its high theoretical specific capacity (3572 mAh g-1). However, a disadvantage when using a Si negative electrode for LIBs is the abrupt drop of its capabilities during the cycling process. Therefore, there have been a few studies of polymers such as poly(vinylidene fluoride) (PVdF), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR) and polyacrylic acid (PAA) given that the robust structure of a polymeric binder to LIBs anodes is a promising means by which to enhance the performance of high-capacity anodes. These studies essentially focused mainly on modifying of the linear-polymer component or on copolymers dissolved in solvents. Cross-linking polymers as a binder may be preferred due to their good scratch resistance, excellent chemical resistance and high levels of adhesion and resilience. However, because these types of polymers (with a rigid structure and cross-linking points) are also insoluble in general organic solvents, applying these types in this capacity is virtually impossible.

  4. Fabrication of Si negative electrodes for Li-ion batteries (LIBs) using cross-linked polymer binders

    PubMed Central

    Jang, Suk-Yong; Han, Sien-Ho

    2016-01-01

    Currently, Si as an active material for LIBs has been attracting much attention due to its high theoretical specific capacity (3572 mAh g−1). However, a disadvantage when using a Si negative electrode for LIBs is the abrupt drop of its capabilities during the cycling process. Therefore, there have been a few studies of polymers such as poly(vinylidene fluoride) (PVdF), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR) and polyacrylic acid (PAA) given that the robust structure of a polymeric binder to LIBs anodes is a promising means by which to enhance the performance of high-capacity anodes. These studies essentially focused mainly on modifying of the linear-polymer component or on copolymers dissolved in solvents. Cross-linking polymers as a binder may be preferred due to their good scratch resistance, excellent chemical resistance and high levels of adhesion and resilience. However, because these types of polymers (with a rigid structure and cross-linking points) are also insoluble in general organic solvents, applying these types in this capacity is virtually impossible. PMID:27991497

  5. Design of an electrolyte composition for stable and rapid charging-discharging of a graphite negative electrode in a bis(fluorosulfonyl)imide-based ionic liquid

    NASA Astrophysics Data System (ADS)

    Matsui, Yukiko; Yamagata, Masaki; Murakami, Satoshi; Saito, Yasuteru; Higashizaki, Tetsuya; Ishiko, Eriko; Kono, Michiyuki; Ishikawa, Masashi

    2015-04-01

    We evaluate the effects of lithium salt on the charge-discharge performance of a graphite negative electrode in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMImFSI) ionic liquid-based electrolytes. Although the graphite negative electrode exhibits good cyclability and rate capability in both 0.43 mol dm-3 LiFSI/EMImFSI and LiTFSI/EMImFSI (TFSI- = bis(trifluoromethylsulfonyl)imide) at room temperature, only the LiFSI/EMImFSI system enables the graphite electrode to be operated with sufficient discharge capacity at the low temperature of 0 °C, even though there is no noticeable difference in ionic conductivity, compared with LiTFSI/EMImFSI. Furthermore, a clear difference in the low-temperature behaviors of the two cells composed of EMImFSI with a high-concentration of lithium salts is observed. Additionally, charge-discharge operation of the graphite electrode at C-rate of over 5.0 can be achieved using of the high-concentration LiFSI/EMImFSI electrolyte. Considering the low-temperature characteristics in both high-concentration electrolytes, the stable and rapid charge-discharge operation in the high-concentration LiFSI/EMImFSI is presumably attributed to a suitable electrode/electrolyte interface with low resistivity. These results suggest that optimization of the electrolyte composition can realize safe and high-performance lithium-ion batteries that utilize ionic liquid-based electrolytes.

  6. Development of non-flammable lithium secondary battery with room-temperature ionic liquid electrolyte: Performance of electroplated Al film negative electrode

    NASA Astrophysics Data System (ADS)

    Ui, Koichi; Yamamoto, Keigo; Ishikawa, Kohei; Minami, Takuto; Takeuchi, Ken; Itagaki, Masayuki; Watanabe, Kunihiro; Koura, Nobuyuki

    The negative electrode performance of the electroplated Al film electrode in the LiCl saturated AlCl 3-1-ethyl-3-methylimizadolium chloride (EMIC) + SOCl 2 melt as the electrolyte for use in non-flammable lithium secondary batteries was evaluated. In the cyclic voltammogram of the electroplated Al film electrode in the melt, the oxidation and reduction waves corresponding to the electrochemical insertion/extraction reactions of the Li + ion were observed at 0-0.80 V vs. Li +/Li, which suggested that the electroplated Al film electrode operated well in the electrolyte. The almost flat potential profiles at about 0.40 V vs. Li +/Li on discharging were shown. The discharge capacity and charge-discharge efficiency was 236 mAh g -1 and 79.2% for the 1st cycle and it maintained 232 mAh g -1 and 77.9% after the 10th cycle. In addition, the initial charge-discharge efficiencies of the electroplated Al film electrode were higher than that of carbon electrodes. The main cathodic polarization reaction was the insertion of Li + ions, and side reactions hardly occurred due to the decomposition reaction of the melt because the Li content corresponding to the electricity was almost totally inserted into the film after charging.

  7. Ti-substituted tunnel-type Na0.44MnO2 oxide as a negative electrode for aqueous sodium-ion batteries

    DOE PAGES

    Wang, Yuesheng; Liu, Jue; Lee, Byungju; ...

    2015-03-25

    The aqueous sodium-ion battery system is a safe and low-cost solution for large-scale energy storage, due to the abundance of sodium and inexpensive aqueous electrolytes. Although several positive electrode materials, e.g., Na0.44MnO2, were proposed, few negative electrode materials, e.g., activated carbon and NaTi2(PO4)3, are available. Here we show that Ti-substituted Na0.44MnO2 (Na0.44[Mn1-xTix]O2) with tunnel structure can be used as a negative electrode material for aqueous sodium-ion batteries. This material exhibits superior cyclability even without the special treatment of oxygen removal from the aqueous solution. Atomic-scale characterizations based on spherical aberration-corrected electron microscopy and ab initio calculations are utilized to accuratelymore » identify the Ti substitution sites and sodium storage mechanism. Ti substitution tunes the charge ordering property and reaction pathway, significantly smoothing the discharge/charge profiles and lowering the storage voltage. Both the fundamental understanding and practical demonstrations suggest that Na0.44[Mn1-xTix]O2 is a promising negative electrode material for aqueous sodium-ion batteries.« less

  8. Porous MoO2 nanowires as stable and high-rate negative electrodes for electrochemical capacitors.

    PubMed

    Zheng, Dezhou; Feng, Haobin; Zhang, Xiyue; He, Xinjun; Yu, Minghao; Lu, Xihong; Tong, Yexiang

    2017-04-04

    Free-standing porous MoO2 nanowires with extraordinary capacitive performance are developed as high-performance electrodes for electrochemical capacitors. The as-obtained MoO2 electrode exhibits a remarkable capacitance of 424.4 mF cm(-2) with excellent electrochemical durability (no capacitance decay after 10 000 cycles at various scan rates).

  9. Controlling the shape change and dendritic growth in Zn negative electrodes for application in Zn/Ni batteries

    NASA Astrophysics Data System (ADS)

    Caldeira, Vincent; Rouget, Robert; Fourgeot, Fabrice; Thiel, Julien; Lacoste, François; Dubau, Laetitia; Chatenet, Marian

    2017-05-01

    Porous zinc electrodes are elaborated, assembled in Zn/Ni 3-4 Ah prismatic batteries and monitored upon charge/discharge cycling (150 cycles at C/3 rate followed by 150 cycles at 1C rate). Migration of zinc within the thickness of the zinc electrodes is revealed by X-Ray radiography, scanning electron microscopy, and X-EDS elemental cartography. Electrodes using either zinc oxide plus calcium hydroxide or directly calcium zincate as active material show similar behavior: neither dendrite formation nor morphological shape changes are observed after 300 charge/discharge cycles. Upon cycling, zinc accumulates at the core of the porous electrode, in the vicinity of the primary current collector and not at the surface, therefore avoiding any risk of dendrite formation. This suggest that the electrode operation is controlled by a core-shell mechanism, with a core of active zinc in the vicinity of the primary current collector, trapped in an electrode shell which is created by the outer portion of the electrode (active material, conductive additives, binder …). However, changing from C/3 to 1C rate after 150 cycles significantly improves the capacity of batteries using calcium zincate; this is correlated to its initial atomic homogeneity associated with higher porosity and an optimal electronic percolation.

  10. Preparation of three-dimensional nanoporous Si using dealloying by metallic melt and application as a lithium-ion rechargeable battery negative electrode

    NASA Astrophysics Data System (ADS)

    Wada, Takeshi; Yamada, Junpei; Kato, Hidemi

    2016-02-01

    Silicon is a promising material for negative electrode in Li-ion batteries because of high gravimetric capacity. A Si nanomaterial that can accommodate volume expansion accompanied by lithiation is needed for practical application in Li-ion batteries. We prepare three-dimensional nanoporous interconnected silicon material with controlled pore and ligament sizes by dealloying using an Mg-Si precursor and Bi melt. The Mg atoms in the precursor selectively dissolve into Bi, and the remaining Si atoms self-organize into a nanoporous structure with characteristic length ranging from several ten to hundred nanometer. The Li-ion battery electrodes made from nanoporous silicon exhibit higher capacities, increased cycle lives, and improved rate performances compared with those made from commercial Si nanoparticles. Measurements on the electrical resistivity and electrode thickness change by lithiation/delithiation suggest that the superior performance of nanoporous Si electrode originates from the following: (1) The nanoporous Si has much lower electrical resistivity compared with that of the nanoparticle Si owing to the n-type dopant incorporated during dealloying. (2) The nanoporous Si-based electrode has higher porosity owing to the presence of intra-particle pores, which can accommodate Si expansion up to higher levels of lithiation.

  11. Spin-Filtering Rectifying and Negative Differential Resistance Behaviors in Co(dmit)2 Molecular Devices with Monatomic (C, Fe, Au) Electrodes

    NASA Astrophysics Data System (ADS)

    Yan, Shenlang; Long, Mengqiu; Zhang, Xiaojiao; He, Jun; Xu, Hui; Gao, Yongli

    2014-09-01

    Using nonequilibrium Green's functions (NEGFs) combined with the density functional theory (DFT), we study the electronic transport properties of a single molecule magnet Co(dmit)2, which is sandwiched between two monatomic chain electrodes, and the different electrode materials carbon, iron and gold, have been considered. The results show that the electrodes play a crucial role in the spin-dependent transport of the Co(dmit)2 molecular device, and some interesting phenomenon, such as perfect spin-filtering effect, rectifying and negative differential resistance (NDR) can be observed. We demonstrated that the magnetic Fe electrode can lead to high spin-flittering effect, and the different hybridization and alignment of energy levels between the molecule and the electrodes may be responsible for the rectification performance, and the distributions (delocalization or localization) of the frontier molecular orbitals under different bias result in the NDR behaviors. These characteristics could be used in the study of spin physics and the realization of nanospintronic devices.

  12. Beneficial effects of activated carbon additives on the performance of negative lead-acid battery electrode for high-rate partial-state-of-charge operation

    NASA Astrophysics Data System (ADS)

    Xiang, Jiayuan; Ding, Ping; Zhang, Hao; Wu, Xianzhang; Chen, Jian; Yang, Yusheng

    2013-11-01

    Experiments are made with negative electrode of 2 V cell and 12 V lead-acid battery doped with typical activated carbon additives. It turns out that the negative electrode containing tens-of-micron-sized carbon particles in NAM exhibits markedly increased HRPSoC cycle life than the one containing carbon particles with much smaller size of several microns or the one containing no activated carbon. The improved performance is mainly attributed to the optimized NAM microstructure and the enhanced electrode reaction kinetics by introducing appropriate activated carbon. The beneficial effects can be briefly summarized from three aspects. First, activated carbon acts as new porous-skeleton builder to increase the porosity and active surface of NAM, and thus facilitates the electrolyte diffusion from surface to inner and provides more sites for crystallization/dissolution of lead sulfate; second, activated carbon plays the role of electrolyte supplier to provide sufficient H2SO4 in the inner of plate when the diffusion of H2SO4 from plate surface cannot keep pace of the electrode reaction; Third, activated carbon acts as capacitive buffer to absorb excess charge current which would otherwise lead to insufficient NAM conversion and hydrogen evolution.

  13. Influence of the structure of the anion in an ionic liquid electrolyte on the electrochemical performance of a silicon negative electrode for a lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Kazuki; Domi, Yasuhiro; Usui, Hiroyuki; Shimizu, Masahiro; Matsumoto, Kuninobu; Nokami, Toshiki; Itoh, Toshiyuki; Sakaguchi, Hiroki

    2017-01-01

    We investigated the influence of the anions in ionic liquid electrolytes on the electrochemical performance of a silicon (Si) negative electrode for a lithium-ion battery. While the electrode exhibited poor cycle stability in tetrafluoroborate-based and propylene carbonate-based electrolytes, better cycle performance was achieved in bis(fluorosulfonyl)amide (FSA-)- and bis(trifluoromethanesulfonyl)amide (TFSA-)-based electrolytes, in which the discharge capacity of a Si electrode was more than 1000 mA h g-1 at the 100th cycle. It is considered that a surface film derived from FSA-- and TFSA--based electrolytes effectively suppressed continuous decomposition of the electrolyte. In a capacity limitation test, a discharge capacity of 1000 mA h g-1 was maintained even after about the 1600th cycle in the FSA--based electrolyte, which corresponds to a cycle life almost twice as long as that in TFSA--based electrolyte. This result should be explained by the high structural stability of FSA--derived surface film. In addition, better rate capability with a discharge capacity of 700 mA h g-1 was obtained at a high current rate of 6 C (21 A g-1) in FSA--based electrolyte, which was 7-fold higher than that in TFSA--based electrolyte. These results clarified that FSA--based ionic liquid electrolyte is the most promising candidate for Si-based negative electrodes.

  14. Performance of the “SiO”-carbon composite-negative electrodes for high-capacity lithium-ion batteries; prototype 14500 batteries

    NASA Astrophysics Data System (ADS)

    Yamada, Masayuki; Uchitomi, Kazutaka; Ueda, Atsushi; Matsumoto, Kazunobu; Ohzuku, Tsutomu

    2013-03-01

    Prototype 14500 batteries (14 mm dia. and 50 mm hgt.; AA size) consisted of the “SiO”-carbon composite-negative and LiCo1/3Ni1/3Mn1/3O2/LiCoO2 (7/3 by weight)-positive electrodes were designed, fabricated and examined in voltage ranging from 2.5 to 4.2 V at -20, -10, 0, and +23 °C. The batteries were stored and delivered 1 Ah at 200 mA and 0.96 Ah at 2 A, and the capacity remained after 300 cycles at 23 °C was 0.7 Ah. Abuse tests, such as overcharging to 12 V, nail penetration, and heating of fully charged batteries in an oven at 150 °C, were also carried out and shown that the batteries showed neither smoke nor fire for all the tests examined. The battery performance was compared to that of conventional batteries with graphite-negative electrodes in the same size and the characteristic features of the lithium-ion batteries with the SiO-carbon composite-negative electrodes were discussed from the experimental results.

  15. Surface properties and graphitization of polyacrylonitrile based fiber electrodes affecting the negative half-cell reaction in vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Langner, J.; Bruns, M.; Dixon, D.; Nefedov, A.; Wöll, Ch.; Scheiba, F.; Ehrenberg, H.; Roth, C.; Melke, J.

    2016-07-01

    Carbon felt electrodes for vanadium redox flow batteries are obtained by the graphitization of polyacrylonitrile based felts at different temperatures. Subsequently, the surface of the felts is modified via thermal oxidation at various temperatures. A single-cell experiment shows that the voltage efficiency is increased by this treatment. Electrode potentials measured with reference electrode setup show that this voltage efficiency increase is caused mainly by a reduction of the overpotential of the negative half-cell reaction. Consequently, this reaction is investigated further by cyclic voltammetry and the electrode activity is correlated with structural and surface chemical properties of the carbon fibers. By Raman, X-ray photoelectron and near edge X-ray absorption fine structure spectroscopy the role of edge sites and oxygen containing functional groups (OCFs) for the electrochemical activity are elucidated. A significant activity increase is observed in correlation with these two characteristics. The amount of OCFs is correlated with structural defects (e.g. edge sites) of the carbon fibers and therefore decreases with an increasing graphitization degree. Thus, for the same thermal oxidation temperature carbon fibers graphitized at a lower temperature show higher activities than those graphitized at a higher temperature.

  16. The synergistic effects of combining the high energy mechanical milling and wet milling on Si negative electrode materials for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Hou, Shang-Chieh; Su, Yuh-Fan; Chang, Chia-Chin; Hu, Chih-Wei; Chen, Tsan-Yao; Yang, Shun-Min; Huang, Jow-Lay

    2017-05-01

    The submicro-sized and nanostructured Si aggregated powder is prepared by combinational routes of high energy mechanical milling (HEMM) and wet milling. Milled Si powder is investigated by particle size analyzer, SEM, TEM, XPS and XRD as well as the control ones. Its electrode is also investigated by in situ XRD and electrochemical performance. Morphology reveals that combining the high energy mechanical milling and wet milling not only fracture primary Si particles but also form submicro-sized Si aggregates constructed by amorphous and nanocrystalline phases. Moreover, XPS shows that wet milling in ethanol trigger Sisbnd Osbnd CH2CH3 bonding on Si surface might enhance the SEI formation. In situ XRD analysis shows negative electrode made of submicro-sized Si aggregated powder can effectively suppress formation of crystalline Li15Si4 during lithiation and delithiation due to amorphous and nanocrystalline construction. Thus, the submicro-sized Si powder with synergistic effects combining the high energy mechanical milling and wet milling in ethanol as negative electrode performs better capacity retention.

  17. Metal hydride-based materials towards high performance negative electrodes for all-solid-state lithium-ion batteries.

    PubMed

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

    2015-06-18

    Electrode performances of MgH2-LiBH4 composite materials for lithium-ion batteries have been studied using LiBH4 as the solid-state electrolyte, which shows a high reversible capacity of 1650 mA h g(-1) with an extremely low polarization of 0.05 V, durable cyclability and robust rate capability.

  18. Asymmetric Paper Supercapacitor Based on Amorphous Porous Mn3O4 Negative Electrode and Ni(OH)2 Positive Electrode: A Novel and High-Performance Flexible Electrochemical Energy Storage Device.

    PubMed

    Feng, Jin-Xian; Ye, Sheng-Hua; Lu, Xue-Feng; Tong, Ye-Xiang; Li, Gao-Ren

    2015-06-03

    Here we synthesize novel asymmetric all-solid-state paper supercapacitors (APSCs) based on amorphous porous Mn3O4 grown on conducting paper (NGP) (Mn3O4/NGP) negative electrode and Ni(OH)2 grown on NGP (Ni(OH)2/NGP) as positive electrode, and they have attracted intensive research interest owing to their outstanding properties such as being flexible, ultrathin, and lightweight. The fabricated APSCs exhibit a high areal Csp of 3.05 F/cm3 and superior cycling stability. The novel asymmetric APSCs also exhibit high energy density of 0.35 mW h/cm3, high power density of 32.5 mW/cm3, and superior cycling performance (<17% capacitance loss after 12,000 cycles at a high scan rate of 100 mV/s). This work shows the first example of amorphous porous metal oxide/NGP electrodes for the asymmetric APSCs, and these systems hold great potential for future flexible electronic devices.

  19. Spin-filtering, giant magnetoresistance, rectifying and negative differential resistance effects in planar four-coordinate Fe complex with graphene nanoribbon electrodes

    NASA Astrophysics Data System (ADS)

    Zhao, P.; Wu, Q. H.; Liu, D. S.; Chen, G.

    2014-01-01

    By using the nonequilibrium Green's function formalism combined with the density functional theory, we have investigated the spin-polarized transport properties of a planar four-coordinate Fe complex sandwiched between two zigzag-edge graphene nanoribbon (ZGNR) electrodes, where the ZGNRs are modulated by external magnetic field. The results show that the system can exhibit perfect dual spin-filtering and spin-rectifying effects at a wide bias range, giant magnetoresistance effect with large magnetoresistance ratio at small bias, and obvious negative differential resistance behavior. The mechanisms are proposed for these phenomena.

  20. Conductive Polymer Binder for High-Tap-Density Nanosilicon Material for Lithium-Ion Battery Negative Electrode Application.

    PubMed

    Zhao, Hui; Wei, Yang; Qiao, Ruimin; Zhu, Chenhui; Zheng, Ziyan; Ling, Min; Jia, Zhe; Bai, Ying; Fu, Yanbao; Lei, Jinglei; Song, Xiangyun; Battaglia, Vincent S; Yang, Wanli; Messersmith, Phillip B; Liu, Gao

    2015-12-09

    High-tap-density silicon nanomaterials are highly desirable as anodes for lithium ion batteries, due to their small surface area and minimum first-cycle loss. However, this material poses formidable challenges to polymeric binder design. Binders adhere on to the small surface area to sustain the drastic volume changes during cycling; also the low porosities and small pore size resulting from this material are detrimental to lithium ion transport. This study introduces a new binder, poly(1-pyrenemethyl methacrylate-co-methacrylic acid) (PPyMAA), for a high-tap-density nanosilicon electrode cycled in a stable manner with a first cycle efficiency of 82%-a value that is further improved to 87% when combined with graphite material. Incorporating the MAA acid functionalities does not change the lowest unoccupied molecular orbital (LUMO) features or lower the adhesion performance of the PPy homopolymer. Our single-molecule force microscopy measurement of PPyMAA reveals similar adhesion strength between polymer binder and anode surface when compared with conventional polymer such as homopolyacrylic acid (PAA), while being electronically conductive. The combined conductivity and adhesion afforded by the MAA and pyrene copolymer results in good cycling performance for the high-tap-density Si electrode.

  1. Spray drying method for large-scale and high-performance silicon negative electrodes in Li-ion batteries.

    PubMed

    Jung, Dae Soo; Hwang, Tae Hoon; Park, Seung Bin; Choi, Jang Wook

    2013-05-08

    Nanostructured silicon electrodes have shown great potential as lithium ion battery anodes because they can address capacity fading mechanisms originating from large volume changes of silicon alloys while delivering extraordinarily large gravimetric capacities. Nonetheless, synthesis of well-defined silicon nanostructures in an industrially adaptable scale still remains as a challenge. Herein, we adopt an industrially established spray drying process to enable scalable synthesis of silicon-carbon composite particles in which silicon nanoparticles are embedded in porous carbon particles. The void space existing in the porous carbon accommodates the volume expansion of silicon and thus addresses the chronic fading mechanisms of silicon anodes. The composite electrodes exhibit excellent electrochemical performance, such as 1956 mAh/g at 0.05C rate and 91% capacity retention after 150 cycles. Moreover, the spray drying method requires only 2 s for the formation of each particle and allows a production capability of ~10 g/h even with an ultrasonic-based lab-scale equipment. This investigation suggests that established industrial processes could be adaptable to the production of battery active materials that require sophisticated nanostructures as well as large quantity syntheses.

  2. Characteristics of coke carbon modified with mesophase-pitch as a negative electrode for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Sato, Yuichi; Kikuchi, Yasuo; Nakano, Takeshi; Okuno, Gaku; Kobayakawa, Koichi; Kawai, Takanobu; Yokoyama, Akira

    To increase the charge-discharge capacity of carbon electrodes for lithium ion secondary batteries, coke carbon, a relatively cheap material, was modified with mesophase-pitch carbon by a heat treatment. While coke carbon powder, mesophase-pitch, and a mixture thereof (4:1 by weight) supplied between 0 and 1.5 V vs. Li/Li + an initial discharge capacity of about 295 mAh/g, 310 mAh/g, and 310 mAh/g, respectively, the modified coke deintercalated 400 mA h/g of lithium with a high degree of reversibility. The difference in capacity between the modified carbon and mixture are discussed based on the shape of their current-potential curves and their galvanostatic charge-discharge curves.

  3. Hierarchical self-assembled structures based on nitrogen-doped carbon nanotubes as advanced negative electrodes for Li-ion batteries and 3D microbatteries

    NASA Astrophysics Data System (ADS)

    Sharifi, Tiva; Valvo, Mario; Gracia-Espino, Eduardo; Sandström, Robin; Edström, Kristina; Wågberg, Thomas

    2015-04-01

    Hierarchical structures based on carbon paper and multi-walled nitrogen-doped carbon nanotubes were fabricated and subsequently decorated with hematite nanorods to obtain advanced 3D architectures for Li-ion battery negative electrodes. The carbon paper provides a versatile metal-free 3D current collector ensuring a good electrical contact of the active materials to its carbon fiber network. Firstly, the nitrogen-doped carbon nanotubes onto the carbon paper were studied and a high footprint area capacity of 2.1 mAh cm-2 at 0.1 mA cm-2 was obtained. The Li can be stored in the inter-wall regions of the nanotubes, mediated by the defects formed on their walls by the nitrogen atoms. Secondly, the incorporation of hematite nanorods raised the footprint area capacity to 2.25 mAh cm-2 at 0.1 mA cm-2. However, the repeated conversion/de-conversion of Fe2O3 limited both coulombic and energy efficiencies for these electrodes, which did not perform as well as those including only the N-doped carbon nanotubes at higher current densities. Thirdly, long-cycling tests showed the robust Li insertion mechanism in these N-doped carbonaceous structures, which yielded an unmatched footprint area capacity enhancement up to 1.95 mAh cm-2 after 60 cycles at 0.3 mA cm-2 and an overall capacity of 204 mAh g-1 referred to the mass of the entire electrode.

  4. Superior performance of asymmetric supercapacitor based on reduced graphene oxide-manganese carbonate as positive and sono-chemically reduced graphene oxide as negative electrode materials

    NASA Astrophysics Data System (ADS)

    Jana, Milan; Kumar, J. Sharath; Khanra, Partha; Samanta, Pranab; Koo, Hyeyoung; Murmu, Naresh Chandra; Kuila, Tapas

    2016-01-01

    A novel strategy to synthesize hierarchical rod like MnCO3 on the reduced graphene oxide (RGO) sheets by a facile and cost-effective hydrothermal method is demonstrated. The chelating action of citric acid facilitates the formation a complex intermediate of Mn2+ and citrate ions, which finally results a 3D MnCO3/RGO (MRGO) composite with high electrical conductivity (∼1056 S m-1), good surface area (59 m2 g-1) and high pore volume (0.3 cm3 g-1). The specific capacitance (SC) of the MRGO composite is ∼1120 F g-1 at a current density of 2 A g-1 in three electrode system. An asymmetric device has been designed with MRGO as positive and sono-chemically reduced RGO (SRGO) as negative electrode material. The asymmetric device (MRGO//SRGO) shows the SC of ∼318 F g-1 (at 2 A g-1) and energy density of ∼113 W h kg-1 (at 1600 W kg-1). The true energy density (1.7 W h kg-1) has been calculated considering the total weight of the device. The MRGO//SRGO device can power a wall clock for ∼13 min after full charging. The Nyquist plot of the asymmetric cell has been simulated with Z-View software to measure the solution resistance, charge-transfer resistance and Warburg elements.

  5. Three-dimensional modeling of a negative ion source with a magnetic filter: impact of biasing the plasma electrode on the plasma asymmetry

    NASA Astrophysics Data System (ADS)

    Fubiani, G.; Boeuf, J. P.

    2015-10-01

    The effect on the plasma characteristics of biasing positively the plasma electrode (PE) in negative ion sources with a magnetic filter is analysed using a 3D particle-in-cell model with Monte-Carlo collisions (PIC-MCC). We specialize to the one driver (i.e. one inductively coupled radio-frequency discharge) BATMAN negative ion source and the 4-drivers (large volume) ELISE device. Both are ITER prototype high power tandem-type negative ion sources developed for the neutral beam injector (NBI) system. The plasma is generated in the driver and diffuses inside the second chamber which is magnetized. Asymmetric plasma profiles originate from the formation of an electric field transverse to the electron current flowing through the magnetic filter (Hall effect). The model shows that the importance of the asymmetry increases with the PE bias potential, i.e. with the electron flow from the driver to the extraction region and depends on the shape of the magnetic filter field. We find that although the plasma density and potential profiles may be more or less asymmetric depending on the filter field configuration, the electron current to the plasma grid is always strongly asymmetric.

  6. Influence of the electron cross-field diffusion in negative ion sources with the transverse magnetic field and the plasma-electrode bias

    SciTech Connect

    Kuppel, S.; Matsushita, D.; Hatayama, A.; Bacal, M.

    2010-02-15

    The physical mechanisms involved in the extraction of H{sup -} ions from the negative ion source are studied with a PIC 2D3V code. The effect of a weak magnetic field transverse to the extraction direction is taken into account, along with a variable bias voltage applied on the plasma electrode (PE). In addition to previous modeling works, the electron diffusion across the magnetic field is taken into account as a simple one-dimensional random-walk process. The results show that without PE bias, the value of the diffusion coefficient has a significant influence upon the value of the extracted H{sup -} current. However, the value of this coefficient does not affect qualitatively the mechanism leading to the peak of extracted H{sup -} ion current observed for an optimum value of the PE bias.

  7. Alternating electric fields combined with activated carbon for disinfection of Gram negative and Gram positive bacteria in fluidized bed electrode system.

    PubMed

    Racyte, Justina; Bernard, Séverine; Paulitsch-Fuchs, Astrid H; Yntema, Doekle R; Bruning, Harry; Rijnaarts, Huub H M

    2013-10-15

    Strong electric fields for disinfection of wastewaters have been employed already for several decades. An innovative approach combining low strength (7 V/cm) alternating electric fields with a granular activated carbon fluidized bed electrode (FBE) for disinfection was presented recently. For disinfection performance of FBE several pure microbial cultures were tested: Bacillus subtilis, Bacillus subtilis subsp. subtilis, Enterococcus faecalis as representatives from Gram positive bacteria and Erwinia carotovora, Pseudomonas luteola, Pseudomonas fluorescens and Escherichia coli YMc10 as representatives from Gram negative bacteria. The alternating electric field amplitude and shape were kept constant. Only the effect of alternating electric field frequency on disinfection performance was investigated. From the bacteria tested, the Gram negative strains were more susceptible and the Gram positive microorganisms were more resistant to FBE disinfection. The collected data indicate that the efficiency of disinfection is frequency and strain dependent. During 6 h of disinfection, the decrease above 2 Log units was achieved with P. luteola and E. coli at 10 kHz and at dual frequency shift keying (FSK) modulated signal with frequencies of 10 kHz and 140 kHz. FBE technology appears to offer a new way for selective bacterial disinfection, however further optimizations are needed on treatment duration, and energy input, to improve effectiveness.

  8. Uncharged positive electrode composition

    DOEpatents

    Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

    1977-03-08

    An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

  9. Effects of the extraction voltage applied by the puller-electrode on the H- extraction in the Linac4 negative ion source

    NASA Astrophysics Data System (ADS)

    Abe, S.; Nishioka, S.; Mattei, S.; Hatayama, A.; Lettry, J.

    2017-08-01

    In order to understand the H- extraction mechanism and investigate the effect of the extraction voltage applied by the puller-electrode on the H- extraction in the Linac4 negative ion source, we are developing a 2D3V-PIC (two dimensions in the real space and three dimensions in the velocity space, Particle in Cell) model with volume produced H- ions. It is shown that how to take the magnetic filter field direction is important for the 2D modeling to take into account the important 3D effect of electron E×B drift. It is also shown that the meniscus formation is not symmetric due to the electron E×B drift in the extraction region and the divergence of the H- beam is asymmetric. In order to make more quantitative comparison of the extracted H- and electron currents with the experiments and 3D modeling, further improvements, especially the electron loss along the magnetic filter field line will be needed.

  10. X-ray photoelectron spectroscopy of negative electrodes from high-power lithium-ion cells showing various levels of power fade

    SciTech Connect

    Herstedt, Marie; Abraham, Daniel P.; Kerr, John B.

    2004-02-28

    High-power lithium-ion cells for transportation applications are being developed and studied at Argonne National Laboratory. The current generation of cells containing LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}-based cathodes, graphite-based anodes, and LiPF6-based electrolytes show loss of capacity and power during accelerated testing at elevated temperatures. Negative electrode samples harvested from some cells that showed varying degrees of power and capacity fade were examined by X-ray photoelectron spectroscopy (XPS). The samples exhibited a surface film on the graphite, which was thicker on samples from cells that showed higher fade. Furthermore, solvent-based compounds were dominant on samples from low power fade cells, whereas LiPF{sub 6}-based products were dominant on samples from high power fade cells. The effect of sample rinsing and air exposure is discussed. Mechanisms are proposed to explain the formation of compounds suggested by the XPS data.

  11. New chemical approach to obtain dense layer phosphate-based ionic conductor coating on negative electrode material surface: Synthesis way, outgassing and improvement of C-rate capability

    NASA Astrophysics Data System (ADS)

    Fleutot, Benoit; Davoisne, Carine; Gachot, Grégory; Cavalaglio, Sébastien; Grugeon, Sylvie; Viallet, Virginie

    2017-04-01

    Li4Ti5O12 (LTO) based batteries have severe gassing behavior during charge/discharge and storage process, due to interfacial reactions between active material and electrolyte solution. In the same time, the electronic and ionic conductivity of pristine LTO is very poor and induces the use of nanoparticles which increase the outgassing phenomena. The coating of LTO particles could be a solution. For this the LTO spinel particles are modified with ionic conductor Li3PO4 coating using a spray-drying method. For the first time a homogeneous thin dense layer phosphate based conductor is obtained without nanoparticles, as a thin film material. It is so possible to study the influence of ionic conductor deposited on the negative electrode material on performances by the controlled layer thickness. This coating was characterized by XRD, SEM, XPS and TEM. The electrochemical performance of Li3PO4 coated Li4Ti5O12 is improved at high C-rate by the surface modification (improvement of 30 mAh g-1 at 5 C-rate compared to pristine LTO for 5 nm of coating), inducing by a modification of surface energy. An optimum coating thickness was studied. This type of coating allows a significant decrease of outgassing phenomena due the conformal coating and opens the way to a great number of studies and new technologies.

  12. Protein-mediated layer-by-layer synthesis of TiO₂(B)/anatase/carbon coating on nickel foam as negative electrode material for lithium-ion battery.

    PubMed

    Wang, Xiaobo; Yan, Yong; Hao, Bo; Chen, Ge

    2013-05-01

    Through an aqueous, protein-mediated layer-by-layer titania deposition process, we have fabricated a protamine/titania composite layer on nickel foam. The coating was composed of amorphous carbon and TiO2(B)/anatase nanoparticles and formed upon organic pyrolysis under a reducing atmosphere (5% H2-Ar mixture). X-ray diffraction analyses, Auger electron spectroscopy, and high-resolution transmission electron microscopy revealed that the obtained coatings contained fine monoclinic TiO2(B) and anatase nanocrystals, along with amorphous carbon. Moreover, the coating can be used as a binder-free negative electrode material for lithium-ion batteries and exhibits high reversible capacity and fast charge-discharge properties; a reversible capacity of 245 mAh g(-1) was obtained at a current density of 50 mA g(-1), and capacities of 167 and 143 mAh g(-1) were obtained at current densities of 1 and 2 A g(-1), respectively.

  13. Ti-substituted tunnel-type Na0.44MnO2 oxide as a negative electrode for aqueous sodium-ion batteries

    SciTech Connect

    Wang, Yuesheng; Liu, Jue; Lee, Byungju; Qiao, Ruimin; Yang, Zhenzhong; Xu, Shuyin; Yu, Xiqian; Gu, Lin; Hu, Yong-Sheng; Yang, Wanli; Kang, Kisuk; Li, Hong; Yang, Xiao-Qing; Chen, Liquan; Huang, Xuejie

    2015-03-25

    The aqueous sodium-ion battery system is a safe and low-cost solution for large-scale energy storage, due to the abundance of sodium and inexpensive aqueous electrolytes. Although several positive electrode materials, e.g., Na0.44MnO2, were proposed, few negative electrode materials, e.g., activated carbon and NaTi2(PO4)3, are available. Here we show that Ti-substituted Na0.44MnO2 (Na0.44[Mn1-xTix]O2) with tunnel structure can be used as a negative electrode material for aqueous sodium-ion batteries. This material exhibits superior cyclability even without the special treatment of oxygen removal from the aqueous solution. Atomic-scale characterizations based on spherical aberration-corrected electron microscopy and ab initio calculations are utilized to accurately identify the Ti substitution sites and sodium storage mechanism. Ti substitution tunes the charge ordering property and reaction pathway, significantly smoothing the discharge/charge profiles and lowering the storage voltage. Both the fundamental understanding and practical demonstrations suggest that Na0.44[Mn1-xTix]O2 is a promising negative electrode material for aqueous sodium-ion batteries.

  14. Analytical modeling and simulation of electrochemical charge/discharge behavior of Si thin film negative electrodes in Li-ion cells

    NASA Astrophysics Data System (ADS)

    Jagannathan, M.; Chandran, K. S. Ravi

    2014-02-01

    Physically-based analytical models that provide insights into the diffusion and/or interface charge transfer effects in bulk (lithiating/delithiating) electrodes are needed to truly assess the performance/limitations of electrode materials for Li-ion batteries. In this context, an analytical modeling framework is constructed here to predict the electrochemical charge-discharge characteristics during lithiation and delithiation of solid amorphous Si (a-Si) thin film electrodes. The framework includes analytical expressions that satisfy Fick's second law for Li transport and the requisite flux boundary conditions of lithiation and delithiation steps. The expressions are derived here by the method of separation of variables. They enable the determination of transient Li concentration profiles in the thin film electrode as a function of state of charge/discharge. The time-dependent electrode surface concentrations (at the electrode-electrolyte interface) obtained from these profiles were used to determine the activation overpotentials and thus, the non-equilibrium cell potentials, as a function of state of charge/discharge using Butler-Volmer kinetics. The simulated charge/discharge characteristics agreed well with the experimental data of a-Si thin film electrodes obtained at different C-rates. The model offers insights into how the charge-discharge behavior is controlled by diffusion limitation within electrode and/or the activation overpotentials at the interface. The analytical framework is also shown to predict successfully the hysteretic behavior of lithiation/delithiation voltage curves.

  15. NiCd battery electrodes, C-150

    NASA Technical Reports Server (NTRS)

    Holleck, G.; Turchan, M.; Hopkins, J.

    1972-01-01

    Electrodes for a nongassing negative limited nickel-cadmium cell are discussed. The key element is the development of cadmium electrodes with high hydrogen overvoltage. For this, the following electrode structures were manufactured and their physical and electrochemical characteristics were evaluated: (1) silver-sinter-based Cd electrodes, (2) Teflon-bonded Cd electrodes, (3) electrodeposited Cd sponge, and (4) Cd-sinter structures.

  16. HIGH VOLTAGE ELECTRODES

    DOEpatents

    Murray, J.J.

    1963-04-23

    S>This patent relates to electrode structure for creating an intense direct current electric field which may have a field strength of the order of two to three times that heretofore obtained, with automatic suppression of arcing. The positive electrode is a conventional conductive material such as copper while the negative electrode is made from a special material having a resistivity greater than that of good conductors and less than that of good insulators. When an incipient arc occurs, the moderate resistivity of the negative electrode causes a momentary, localized decrease in the electric field intensity, thus suppressing the flow of electrons and avoiding arcing. Heated glass may be utilized for the negative electrode, since it provides the desired combination of resistivity, capacity, dielectric strength, mechani-cal strength, and thermal stability. (AEC)

  17. Electrophoretic deposition of ligand-free platinum nanoparticles on neural electrodes affects their impedance in vitro and in vivo with no negative effect on reactive gliosis.

    PubMed

    Angelov, Svilen D; Koenen, Sven; Jakobi, Jurij; Heissler, Hans E; Alam, Mesbah; Schwabe, Kerstin; Barcikowski, Stephan; Krauss, Joachim K

    2016-01-12

    Electrodes for neural stimulation and recording are used for the treatment of neurological disorders. Their features critically depend on impedance and interaction with brain tissue. The effect of surface modification on electrode impedance was examined in vitro and in vivo after intracranial implantation in rats. Electrodes coated by electrophoretic deposition with platinum nanoparticles (NP; <10 and 50 nm) as well as uncoated references were implanted into the rat's subthalamic nucleus. After postoperative recovery, rats were electrostimulated for 3 weeks. Impedance was measured before implantation, after recovery and then weekly during stimulation. Finally, local field potential was recorded and tissue-to-implant reaction was immunohistochemically studied. Coating with NP significantly increased electrode's impedance in vitro. Postoperatively, the impedance of all electrodes was temporarily further increased. This effect was lowest for the electrodes coated with particles <10 nm, which also showed the most stable impedance dynamics during stimulation for 3 weeks and the lowest total power of local field potential during neuronal activity recording. Histological analysis revealed that NP-coating did not affect glial reactions or neural cell-count. Coating with NP <10 nm may improve electrode's impedance stability without affecting biocompatibility. Increased impedance after NP-coating may improve neural recording due to better signal-to-noise ratio.

  18. DAN DORNEY

    NASA Image and Video Library

    2016-03-16

    CHIEF ENGINEER OF THE LAUNCH VEHICLE FOR NASA'S COMMERCIAL CREW PROGRAM, DAN DORNEY GUIDES THE TEAM EVALUATING THE VEHICLES CREATED BY INDUSTRY PARTNERS AND ENSURES THE ROCKETS MEET THE REQUIREMENTS TO SAFELY CARRY ASTRONAUTS TO THE INTERNATIONAL SPACE STATION.

  19. The chemical changes occurring upon cycling of a SnO 2 negative electrode for lithium ion cell: In situ Mössbauer investigation

    NASA Astrophysics Data System (ADS)

    Sandu, I.; Brousse, T.; Schleich, D. M.; Danot, M.

    2006-02-01

    Electrochemical reduction of a SnO 2 electrode for a lithium ion cell is known to result in formation of Li 4.4Sn alloy+2Li 2O. In order to determine to which extent such an electrode can be considered as reversible, we studied the electrochemical oxidation of a previously reduced SnO 2 electrode, using in situ 119Sn Mössbauer spectroscopy. Contrary to what could be expected, the first step does not consist in extraction of lithium from Li 4.4Sn for β-Sn to be obtained. In fact, simple lithium extraction proceeds only down to the Li 1.4Sn composition. Further oxidation (second step) involves formation of unusual species (Sn(0) and oxygen-surrounded Sn(II), both probably in interaction with Li 2O). Then (third step), red SnO-like Sn(II) species are formed, along with some Sn(IV). Especially during the second and third steps, the working electrode is far from thermodynamic equilibrium despite the low oxidation rate. This non-equilibrium behavior is probably related to the ultrafine particle size resulting from electrochemical grinding.

  20. The Cerberus/Dan-family protein Charon is a negative regulator of Nodal signaling during left-right patterning in zebrafish.

    PubMed

    Hashimoto, Hisashi; Rebagliati, Michael; Ahmad, Nadira; Muraoka, Osamu; Kurokawa, Tadahide; Hibi, Masahiko; Suzuki, Tohru

    2004-04-01

    We have isolated a novel gene, charon, that encodes a member of the Cerberus/Dan family of secreted factors. In zebrafish, Fugu and flounder, charon is expressed in regions embracing Kupffer's vesicle, which is considered to be the teleost fish equivalent to the region of the mouse definitive node that is required for left-right (L/R) patterning. Misexpression of Charon elicited phenotypes similar to those of mutant embryos defective in Nodal signaling or embryos overexpressing Antivin(Atv)/Lefty1, an inhibitor for Nodal and Activin. Charon also suppressed the dorsalizing activity of all three of the known zebrafish Nodal-related proteins (Cyclops, Squint and Southpaw), indicating that Charon can antagonize Nodal signaling. Because Southpaw functions in the L/R patterning of lateral plate mesoderm and the diencephalon, we asked whether Charon is involved in regulating L/R asymmetry. Inhibition of Charon's function by antisense morpholino oligonucleotides (MOs) led to a loss of L/R polarity, as evidenced by bilateral expression of the left side-specific genes in the lateral plate mesoderm (southpaw, cyclops, atv/lefty1, lefty2 and pitx2) and diencephalon (cyclops, atv/lefty1 and pitx2), and defects in early (heart jogging) and late (heart looping) asymmetric heart development, but did not disturb the notochord development or the atv/lefty1-mediated midline barrier function. MO-mediated inhibition of both Charon and Southpaw led to a reduction in or loss of the expression of the left side-specific genes, suggesting that Southpaw is epistatic to Charon in left-side formation. These data indicate that antagonistic interactions between Charon and Nodal (Southpaw), which take place in regions adjacent to Kupffer's vesicle, play an important role in L/R patterning in zebrafish.

  1. Exploration of Ca0.5Ti2(PO4)3@carbon Nanocomposite as the High-Rate Negative Electrode for Na-Ion Batteries.

    PubMed

    Wei, Zhixuan; Meng, Xing; Yao, Ye; Liu, Qiang; Wang, Chunzhong; Wei, Yingjin; Du, Fei; Chen, Gang

    2016-12-28

    Exploring suitable electrode materials with high specific capacity and high-rate capability is a challenging goal for the development of Na-ion batteries. Here, we report a NASICON-structured compound, Ca0.5Ti2(PO4)3, with respect to its synthesis and electrochemical properties. The electrode is found to enable fast Na(+) ion diffusion owing to the rich crystallographic vacancies, affording a reversible capacity of 264 mA h g(-1) between 3.0 and 0.01 V. In particular, the hybrid Ca0.5Ti2(PO4)3@carbon exhibits remarkable rate performance with a discharge capacity of nearly 45 mA h g(-1) at a current density of 20 A g(-1), which is attributed to the pseudocapacitive effect.

  2. Unipolar model of negative corona discharge: Comparison of calculated and experimental I-V characteristics for the sphere-plane electrode system

    NASA Astrophysics Data System (ADS)

    Mel'nikova, N. V.; Samusenko, A. V.; Safronova, I. F.

    2017-08-01

    Substantial computational resources and time are needed for computer simulation of the corona discharge with allowance for the sheath processes. This circumstance necessitates a search for and development of simplified models in which the processes in the sheath of corona discharge are reduced to the boundary condition at the surface of active electrode. A unipolar model that takes into account only one type of carriers is considered, and the boundary condition on the discharge electrode describes the rate of variations in the electron-flux density from the sheath. The calculated I-V characteristics are compared with experimental data for interelectrode distances ranging from several millimeters to several centimeters to reveal the applicability of the model. The simulated and experimental results are in good agreement at interelectrode distances of greater than 1 cm.

  3. NiCd battery electrodes

    NASA Technical Reports Server (NTRS)

    Holleck, G.; Turchan, M.; Hopkins, J.

    1972-01-01

    The objective of this research program was to develop and evaluate electrodes for a negative limited nickel-cadmium cell and to prove its feasibility. The program consisted of three phases: (1) the development of cadmium electrodes with high hydrogen overvoltage characteristics, (2) the testing of positive and negative plates, and (3) the fabrication and testing of complete negative limited NiCd cells. The following electrode structures were manufactured and their physical and electrochemical characteristics were evaluated: (1) silver sinter-based Cd electrodes, (2) Teflon-bonded Cd electrodes, (3) electrodeposited Cd sponge, and (4) Cd-sinter structures. All cadmium electrode structures showed a sharp increase in potential at the end of charge, with the advent of hydrogen evolution occurring at approximately -1.3 V versus Hg/HgO. The hydrogen advent potentials on pure cadmium structures were 50 to 70 mV more cathodic than those of their silver-containing counterparts.

  4. Electrode for electrochemical cell

    DOEpatents

    Kaun, T.D.; Nelson, P.A.; Miller, W.E.

    1980-05-09

    An electrode structure for a secondary electrochemical cell includes an outer enclosure defining a compartment containing electrochemical active material. The enclosure includes a rigid electrically conductive metal sheet with perforated openings over major side surfaces. The enclosure can be assembled as first and second trays each with a rigid sheet of perforated electrically conductive metal at major side surfaces and normally extending flanges at parametric margins. The trays can be pressed together with moldable active material between the two to form an expandable electrode. A plurality of positive and negative electrodes thus formed are arranged in an alternating array with porous frangible interelectrode separators within the housing of the secondary electrochemical cell.

  5. Electrode for electrochemical cell

    DOEpatents

    Kaun, Thomas D.; Nelson, Paul A.; Miller, William E.

    1981-01-01

    An electrode structure for a secondary electrochemical cell includes an outer enclosure defining a compartment containing electrochemical active material. The enclosure includes a rigid electrically conductive metal sheet with perforated openings over major side surfaces. The enclosure can be assembled as first and second trays each with a rigid sheet of perforated electrically conductive metal at major side surfaces and normally extending flanges at parametric margins. The trays can be pressed together with moldable active material between the two to form an expandable electrode. A plurality of positive and negative electrodes thus formed are arranged in an alternating array with porous frangible interelectrode separators within the housing of the secondary electrochemical cell.

  6. Combustion synthesis of MgFe{sub 2}O{sub 4}/graphene nanocomposite as a high-performance negative electrode for lithium ion batteries

    SciTech Connect

    Rai, Alok Kumar; Thi, Trang Vu; Gim, Jihyeon; Kim, Jaekook

    2014-09-15

    We present a facile and cost-effective urea-assisted auto-combustion method for synthesizing pure MgFe{sub 2}O{sub 4} nanoparticle and MgFe{sub 2}O{sub 4}/graphene nanocomposite samples followed by annealing at 600 °C for 5 h under N{sub 2} atmosphere. The X-ray diffraction pattern confirmed the single phase formation for both samples. The obtained morphology of the nanocomposite sample shows that the MgFe{sub 2}O{sub 4} nanoparticles are highly dispersed on conductive graphene nanosheets with particle size in the range of 50–100 nm. When applied as an anode material, MgFe{sub 2}O{sub 4}/graphene nanocomposite electrode shows a high reversible charge capacity of 764.4 mAh g{sup −1} at 0.04 C over 60 charge/discharge cycles and in spite of that it also retained a capacity of 219.9 mAh g{sup −1} at high current rate of 4.2 C. The obtained result is much better than the synthesized pure MgFe{sub 2}O{sub 4} nanoparticle electrode. The excellent electrochemical performance of the MgFe{sub 2}O{sub 4}/graphene nanocomposite electrode can be attributed to the strong favorable synergistic interaction between MgFe{sub 2}O{sub 4} and reduced graphene nanosheets, which supplied a large number of accessible active sites for Li{sup +}-ion insertion and short diffusion length for both Li{sup +} ions and electrons. In addition, the graphene nanosheets in the nanocomposite electrode provide high conductivity and accommodate the large volume expansion/contraction during cycling, resulting in high capacity and long cycling stability. - Highlights: • MgFe{sub 2}O{sub 4}/graphene nanocomposite was synthesized by facile urea-assisted method. • Such well-designed structure results in fine and strong interfacial interaction. • Nanocomposite anode shows high rate capability and long cycling stability. • Better performance is due to synergistic effect between MgFe{sub 2}O{sub 4} and graphene. • Simple, low cost and fast synthesis is attractive for large scale applications.

  7. Evaluation program for secondary spacecraft cells. Initial evaluation tests of General Electric Company standard and teflonated negative electrode 20.0 ampere-hour, nickel-cadmium spacecraft cells with auxiliary electrodes

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The standard plate cells exhibited higher average end-of-charge (EOC) voltages than the cells with teflonated negative plates; they also delivered a higher capacity output in ampere hours following these charges. All the cells reached a pressure of 20 psia before reaching the voltage limit of 1.550 volts during the pressure versus capacity test. The average ampere hours in and voltages at this pressure were 33.6 and 1.505 volts respectively for the teflonated negative plate cells and 35.5 and 1.523 volts for the standard plate cells. All cells exhibited pressure decay in the range of 1 to 7 psia during the last 30 minutes of the 1-hour open circuit stand. Average capacity out for the teflonated and standard negative plate cells was 29.4 and 29.9 ampere hours respectively.

  8. Group IVA Element (Si, Ge, Sn)-Based Alloying/Dealloying Anodes as Negative Electrodes for Full-Cell Lithium-Ion Batteries.

    PubMed

    Liu, Dequan; Liu, Zheng Jiao; Li, Xiuwan; Xie, Wenhe; Wang, Qi; Liu, Qiming; Fu, Yujun; He, Deyan

    2017-10-10

    To satisfy the increasing energy demands of portable electronics, electric vehicles, and miniaturized energy storage devices, improvements to lithium-ion batteries (LIBs) are required to provide higher energy/power densities and longer cycle lives. Group IVA element (Si, Ge, Sn)-based alloying/dealloying anodes are promising candidates for use as electrodes in next-generation LIBs owing to their extremely high gravimetric and volumetric capacities, low working voltages, and natural abundances. However, due to the violent volume changes that occur during lithium-ion insertion/extraction and the formation of an unstable solid electrolyte interface, the use of Group IVA element-based anodes in commercial LIBs is still a great challenge. Evaluating the electrochemical performance of an anode in a full-cell configuration is a key step in investigating the possible application of the active material in LIBs. In this regard, the recent progress and important approaches to overcoming and alleviating the drawbacks of Group IVA element-based anode materials are reviewed, such as the severe volume variations during cycling and the relatively brittle electrode/electrolyte interface in full-cell LIBs. Finally, perspectives and future challenges in achieving the practical application of Group IVA element-based anodes in high-energy and high-power-density LIB systems are proposed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

    An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

  10. Electrode compositions

    DOEpatents

    Block, Jacob; Fan, Xiyun

    1998-01-01

    An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

  11. Magnetohydrodynamic electrode

    DOEpatents

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

    A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.

  12. Co3O4 negative electrode material for rechargeable sodium ion batteries: An investigation of conversion reaction mechanism and morphology-performances correlations

    NASA Astrophysics Data System (ADS)

    Longoni, Gianluca; Fiore, Michele; Kim, Joo-Hyung; Jung, Young Hwa; Kim, Do Kyung; Mari, Claudio M.; Ruffo, Riccardo

    2016-11-01

    Transition metal oxides have recently aroused a renewed and increasing interest as conversion anode materials for sodium ion batteries. Being their electrochemical performances strongly dependent on morphological aspects, has been here proposed a straightforward approach to modulate morphological characteristics of a transition metal oxide (Co3O4) using a low cost synthetic route. The as obtained optimized morphology allows the realization of high practical specific capacities, higher than 500 mAh g-1 after 50 cycles, and represents a valid candidate for further optimization. In addition to the morphology-performance correlations, the reaction mechanism beyond the electrochemical behavior was also investigated revealing the role of the CoO phase in the charge/discharge process. Finally, an electrode pre-sodiation treatment for conversion materials is presented: it has been indeed demonstrated that it sensibly decreases the irreversible capacity correlated to the first cycle and improves cycle ability.

  13. Li-alloy electrode for Li-alloy/metal sulfide cells

    DOEpatents

    Kaun, Thomas D.

    1996-01-01

    A method of making a negative electrode, the electrode made thereby and a secondary electrochemical cell using the electrode. Lithium, silicon and nickel is alloyed in a prescribed proportion forming an electroactive material, to provide an improved electrode and cell.

  14. Hydrogen-Treated Rutile TiO2 Shell in Graphite-Core Structure as a Negative Electrode for High-Performance Vanadium Redox Flow Batteries.

    PubMed

    Vázquez-Galván, Javier; Flox, Cristina; Fàbrega, Cristian; Ventosa, Edgar; Parra, Andres; Andreu, Teresa; Morante, Joan Ramón

    2017-05-09

    Hydrogen-treated TiO2 as an electrocatalyst has shown to boost the capacity of high-performance all-vanadium redox flow batteries (VRFBs) as a simple and eco-friendly strategy. The graphite felt-based GF@TiO2 :H electrode is able to inhibit the hydrogen evolution reaction (HER), which is a critical barrier for operating at high rate for long-term cycling in VRFBs. Significant improvements in charge/discharge and electron-transfer processes for the V(3+) /V(2+) reaction on the surface of reduced TiO2 were achieved as a consequence of the formation of oxygen functional groups and oxygen vacancies in the lattice structure. Key performance indicators of VRFB have been improved, such as high capability rates and electrolyte-utilization ratios (82 % at 200 mA cm(-2) ). Additionally, high coulombic efficiencies (ca. 100 % up to the 96th cycle, afterwards >97 %) were obtained, demonstrating the feasibility of achieving long-term stability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Monodisperse SnO2 anchored reduced graphene oxide nanocomposites as negative electrode with high rate capability and long cyclability for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Guo, Jinxue; Jiang, Bin; Zhang, Xiao; Liu, Hongtian

    2014-09-01

    In this manuscript, we present a facile and friendly wet chemical method to prepare monodisperse SnO2 nanocrystals assembled on reduced graphene oxide (RGO). Aided with sodium dodecyl sulfonate, small SnO2 nanoparticles (∼5 nm) are deposited onto the flexible support evenly and tightly. A cheap compound, urea, is used for the controlled precipitation of SnO2 and the reduction of graphene oxide. When tested as the anode material, the hybrid composite electrode delivers excellent cyclability at high current density, such as high reversible capacity over 1000 mAh g-1 after 400 cycles at 0.5 A g-1 and ∼560 mAh g-1 after 400 cycles at 1 A g-1. The composites also exhibit superior rate capability varying from 0.1 to 4 A g-1, and possess capacity of 423 mAh g-1 at 4 A g-1. This synthesis strategy seems to be suitable for industrial production and can also be extended to produce a variety of metal oxide/RGO composites.

  16. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  17. Capacitive carbon and electrochemical lead electrode systems at the negative plates of lead-acid batteries and elementary processes on cycling

    NASA Astrophysics Data System (ADS)

    Pavlov, D.; Nikolov, P.

    2013-11-01

    Batteries in hybrid electric vehicles operate in High-Rate Partial-State-of-Charge (HRPSoC) cycling duty. To make lead-acid batteries suitable for this duty, carbon is added to the negative active material. As a result of this technological change, two electrical systems form at the negative plates: (a) a capacitive carbon system comprising high-rate charging and discharging of the electric double layer; low Ah capacity, and (b) a lead electrochemical system, comprising oxidation of Pb to PbSO4 during discharge and vice versa during charge; this system is slow to accept charge, but has high Ah capacity. Through cycling lead-acid cells under HRPSoC conditions with short current pulses of various durations we have established that the processes involved in the capacitive system proceed highly reversibly and complete hundreds of thousands HRPSoC cycles. The number of cycles achieved by the electrochemical system is limited to tens of thousands and lead to progressive sulfation. Carbon added to the negative active material changes the latter's structure. The specific surface of NAM increases and the median pore radius decreases. Some carbon additives may reduce the radius of the pores in NAM to membrane sizes, which may change the chemistry of the electrochemical system.

  18. α-Na2Ni2Fe(PO4)3: a dual positive/negative electrode material for sodium ion batteries.

    PubMed

    Essehli, R; Belharouak, I; Ben Yahia, H; Chamoun, R; Orayech, B; El Bali, B; Bouziane, K; Zhou, X L; Zhou, Z

    2015-03-14

    A new orthophosphate α-Na2Ni2Fe(PO4)3 was synthesized using a solid state reaction route, and its crystal structure was determined from powder X-ray diffraction data. The physical properties of α-Na2Ni2Fe(PO4)3 were studied by magnetic and electrochemical measurements and by Mössbauer and Raman spectroscopy. α-Na2Ni2Fe(PO4)3 crystallizes according to a stuffed α-CrPO4-type structure with the space group Imma and the cell parameters a = 10.42821(12), b = 13.19862(15), c = 6.47634(8) Å, and Z = 4. The structure consists of a 3D-framework of octahedra and tetrahedra sharing corners and/or edges with channels along [100] and [010], in which the sodium atoms are located. The (57)Fe Mössbauer spectrum indicates that the Fe(3+) cation is distributed over two crystallographic sites implying the presence of a Ni(2+)/Fe(3+) statistical disorder. Magnetic susceptibility follows the Curie-Weiss behavior above 100 K with θ = -114.3 K indicating the occurrence of predominant antiferromagnetic interactions. Electrochemical tests indicate that during the first discharge to 1 V vs. Na(+)/Na in a sodium cell, one Na(+) ion could be inserted into the α-Na2Ni2Fe(PO4)3 structure. This has led to the formation of a new phase Na3Ni2Fe(PO4)3 which was found to be promising as a positive electrode material for sodium batteries. When α-Na2Ni2Fe(PO4)3 is further discharged to 0.03 V, it delivers a capacity of 960 mA h g(-1). This corresponds to the intercalation of more than seven sodium atoms per formula unit which is an indication of a conversion-type behaviour with the formation of metallic Fe and Ni. When cycled in the voltage range 0.03-3 V vs. Na(+)/Na, at 20 °C, under the current rates of 50, 100, 200, and 400 mA g(-1), reversible capacities of 238, 196, 153, and 115 mA h g(-1), were obtained, respectively.

  19. NiCd battery electrodes, C-150

    NASA Technical Reports Server (NTRS)

    Holleck, G.

    1971-01-01

    A research program to develop and evaluate electrodes for a nongassing negative limited nickel-cadmium cell is described. The concept of the negative limited cell and its implications on electrode structure are discussed. The key element is the development of a cadmium electrode with high hydrogen overvoltage. For this, Teflon-bonded Cd electrodes and silver-sinter based Gc electrodes were manufactured and in preliminary experiments their physical and electrochemical characteristics were evaluated. Hydrogen evolution on cadmium was found to occur approximately 100 mV more cathodic than on silver. Both electrode structures exhibit a fairly sharp potential rise at the end of the charging cycle and the advent of gas evolution occurs at potentials between -1.2 and -1.3 V versus a Hg/HgO reference electrode. These results are compared with conventional Ni-sinter based Cd electrodes.

  20. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  1. NASICON-Type Mg0.5Ti2(PO4)3 Negative Electrode Material Exhibits Different Electrochemical Energy Storage Mechanisms in Na-Ion and Li-Ion Batteries.

    PubMed

    Zhao, Yingying; Wei, Zhixuan; Pang, Qiang; Wei, Yingjin; Cai, Yongmao; Fu, Qiang; Du, Fei; Sarapulova, Angelina; Ehrenberg, Helmut; Liu, Bingbing; Chen, Gang

    2017-02-08

    A carbon-coated Mg0.5Ti2(PO4)3 polyanion material was prepared by the sol-gel method and then studied as the negative electrode materials for lithium-ion and sodium-ion batteries. The material showed a specific capacity of 268.6 mAh g(-1) in the voltage window of 0.01-3.0 V vs Na(+)/Na(0). Due to the fast diffusion of Na(+) in the NASICON framework, the material exhibited superior rate capability with a specific capacity of 94.4 mAh g(-1) at a current density of 5A g(-1). Additionally, 99.1% capacity retention was achieved after 300 cycles, demonstrating excellent cycle stability. By comparison, Mg0.5Ti2(PO4)3 delivered 629.2 mAh g(-1) in 0.01-3.0 V vs Li(+)/Li(0), much higher than that of the sodium-ion cells. During the first discharge, the material decomposed to Ti/Mg nanoparticles, which were encapsulated in an amorphous SEI and Li3PO4 matrix. Li(+) ions were stored in the Li3PO4 matrix and the SEI film formed/decomposed in subsequent cycles, contributing to the large Li(+) capacity of Mg0.5Ti2(PO4)3. However, the lithium-ion cells exhibited inferior rate capability and cycle stability compared to the sodium-ion cells due to the sluggish electrochemical kinetics of the electrode.

  2. Optimization of reference electrode position in a three-electrode cell for impedance measurements in lithium-ion rechargeable battery by finite element method

    NASA Astrophysics Data System (ADS)

    Hoshi, Yoshinao; Narita, Yuki; Honda, Keiichiro; Ohtaki, Tomomi; Shitanda, Isao; Itagaki, Masayuki

    2015-08-01

    We determine the proper placement of the reference electrode for impedance measurements in lithium-ion rechargeable batteries with a three-electrode cell. Calculations of the impedance spectra of the positive and negative electrodes and simulations of the current and potential distributions between them are performed using the finite element method. In the simulation, the positive and negative electrodes are symmetrical face to face. Distortions of the loops and artifact inductive loops are observed in the impedance spectra of the positive and negative electrodes when the reference electrode is between or at the edges of the electrodes. These distortions and the diameter of the artifact inductive loops become small when the reference electrode is positioned outside the area between the positive and negative electrodes. Simulations also demonstrate that current from the positive electrode can flow to the reference electrode and then the negative electrode, i.e., part of the reference electrode facing the positive electrode becomes cathode and part of the reference electrode facing the negative electrode becomes anode. Therefore, the dissolution of reference electrode occurs during impedance measurements in a three-electrode cell and the reference electrode should be placed outside of the area between electrodes, where there is no potential modulation and gradient.

  3. Subdural Electrodes

    PubMed Central

    Lesser, Ronald P.; Crone, Nathan E.; Webber, W.R.S.

    2010-01-01

    Subdural electrodes are frequently used to aid in the neurophysiological assessment of patients with intractable seizures. We review the indications for these, their uses for localizing epileptogenic regions and for localizing cortical regions supporting movement, sensation, and language. PMID:20573543

  4. Meet EPA's Dan Nelson

    EPA Pesticide Factsheets

    EPA’s Dan Nelson is the Director of the Human Research Protocol Office at the National Health and Environmental Effect Research Laboratory, Dan works to protect the rights and welfare of EPA’s research participants.

  5. Magnetohydrodynamic electrode

    DOEpatents

    Marchant, David D.; Killpatrick, Don H.

    1978-01-01

    An electrode capable of withstanding high temperatures and suitable for use as a current collector in the channel of a magnetohydrodynamic (MHD) generator consists of a sintered powdered metal base portion, the upper surface of the base being coated with a first layer of nickel aluminide, an intermediate layer of a mixture of nickel aluminide - refractory ceramic on the first layer and a third or outer layer of a refractory ceramic material on the intermediate layer. The sintered powdered metal base resists spalling by the ceramic coatings and permits greater electrode compliance to thermal shock. The density of the powdered metal base can be varied to allow optimization of the thermal conductivity of the electrode and prevent excess heat loss from the channel.

  6. Cermet electrode

    DOEpatents

    Maskalick, Nicholas J.

    1988-08-30

    Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

  7. Photoelectrochemical electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Rembaum, A. (Inventor)

    1983-01-01

    The surface of a moderate band gap semiconductor such as p-type molybdenum sulfide is modified to contain an adherent film of charge mediating ionene polymer containing an electroactive unit such as bipyridimium. Electron transport between the electrode and the mediator film is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles of catalyst such as platinum within the film provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition crosslinking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.

  8. Electrochemistry of Carbon Dioxide on Carbon Electrodes.

    PubMed

    Yang, Nianjun; Waldvogel, Siegfried R; Jiang, Xin

    2016-01-04

    Carbon electrodes have the advantages of being chemically inert at negative potential ranges in all media and high offset potentials for hydrogen evolution in comparison to metal electrodes, and therefore are the most suitable electrodes for electrochemistry and electrochemical conversion of CO2 into valuable chemicals. Herein we summarize on carbon electrodes the voltammetry, electrochemical and electrocatalytic CO2 reduction, as well as electron synthesis using CO2 and carbon electrodes. The electrocatalytic CO2 reduction using carbocatalyts and the future activities about electrochemical CO2 conversion are highlighted.

  9. Microvoltammetric Electrodes.

    DTIC Science & Technology

    1985-09-25

    Microvoltammetric Electrodes, J. 0. Howell, R. M. Wightman, Anal. Chem., 56, 524-529 (1984). 2. Flow Rate Independent Amperometric Cell , W. L. Caudill...Electroanal. Chem., 182, 113-122 (1985). C. List of all publications 1. Flow Rate Independent Amperometric Cell , W. L. Caudill, J. 0. Howell, R. M

  10. Capacitance enhancement via electrode patterning

    NASA Astrophysics Data System (ADS)

    Ho, Tuan A.; Striolo, Alberto

    2013-11-01

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  11. Capacitance enhancement via electrode patterning

    SciTech Connect

    Ho, Tuan A.; Striolo, Alberto

    2013-11-28

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  12. Shielded capacitive electrode

    DOEpatents

    Kireeff Covo, Michel

    2013-07-09

    A device is described, which is sensitive to electric fields, but is insensitive to stray electrons/ions and unlike a bare, exposed conductor, it measures capacitively coupled current while rejecting currents due to charged particle collected or emitted. A charged particle beam establishes an electric field inside the beam pipe. A grounded metallic box with an aperture is placed in a drift region near the beam tube radius. The produced electric field that crosses the aperture generates a fringe field that terminates in the back surface of the front of the box and induces an image charge. An electrode is placed inside the grounded box and near the aperture, where the fringe fields terminate, in order to couple with the beam. The electrode is negatively biased to suppress collection of electrons and is protected behind the front of the box, so the beam halo cannot directly hit the electrode and produce electrons. The measured signal shows the net potential (positive ion beam plus negative electrons) variation with time, as it shall be observed from the beam pipe wall.

  13. Sn x[BPO 4] 1-x composites as negative electrodes for lithium ion cells: Comparison with amorphous SnB 0.6P 0.4O 2.9 and effect of composition

    NASA Astrophysics Data System (ADS)

    Conte, Donato Ercole; Aboulaich, Abdelmaula; Robert, Florent; Olivier-Fourcade, Josette; Jumas, Jean-Claude; Jordy, Christian; Willmann, Patrick

    2010-01-01

    A comparative study of two Sn-based composite materials as negative electrode for Li-ion accumulators is presented. The former SnB 0.6P 0.4O 2.9 obtained by in-situ dispersion of SnO in an oxide matrix is shown to be an amorphous tin composite oxide (ATCO). The latter Sn 0.72[BPO 4] 0.28 obtained by ex-situ dispersion of Sn in a borophosphate matrix consists of Sn particles embedded in a crystalline BPO 4 matrix. The electrochemical responses of ATCO and Sn 0.72[BPO 4] 0.28 composite in galvanostatic mode show reversible capacities of about 450 and 530 mAh g -1, respectively, with different irreversible capacities (60% and 29%). Analysis of these composite materials by 119Sn Mössbauer spectroscopy in transmission (TMS) and emission (CEMS) modes confirms that ATCO is an amorphous Sn II composite oxide and shows that in the case of Sn 0.72[BPO 4] 0.28, the surface of the tin clusters is mainly formed by Sn II in an amorphous interface whereas the bulk of the clusters is mainly formed by Sn 0. The determination of the recoilless free fractions f (Lamb-Mössbauer factors) leads to the effective fraction of both Sn 0 and Sn II species in such composites. The influence of chemical composition and especially of the surface-to-bulk tin species ratio on the electrochemical behaviour has been analysed for several Sn x[BPO 4] 1-x composite materials (0.17< x<0.91). The cell using the compound Sn 0.72[BPO 4] 0.28 as active material exhibits interesting electrochemical performances (reversible capacity of 500 mAh g -1 at C/5 rate).

  14. Lithium-aluminum-magnesium electrode composition

    DOEpatents

    Melendres, Carlos A.; Siegel, Stanley

    1978-01-01

    A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

  15. Platinum electrodes for electrochemical detection of bacteria

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.

    1979-01-01

    Bacteria is detected electro-chemically by measuring evolution of hydrogen in test system with platinum and reference electrode. Using system, electrodes of platinum are used to detect and enumerate varieties of gram-positive and gram-negative organisms compared in different media.

  16. Evaluation of electrode polarity on defibrillation efficacy.

    PubMed

    Bardy, G H; Ivey, T D; Allen, M D; Johnson, G; Greene, H L

    1989-02-15

    The effect of electrode polarity on defibrillation thresholds in humans is unknown. This prospective, randomized evaluation of electrode polarity on defibrillation thresholds was performed in 21 survivors of ventricular fibrillation (VF) undergoing cardiac surgery. Defibrillation was always performed with 2 identical large rectangular, wire mesh electrodes positioned over the anterior wall of the right ventricle and the posterolateral wall of the left ventricle. The initial electrode polarity for the left ventricular (LV) electrode was chosen randomly for determination of the defibrillation threshold. Subsequently, electrode polarity was reversed. The defibrillation threshold was defined as the lowest pulse amplitude that would effectively terminate VF with a single discharge delivered 10 seconds after initiation of an episode of VF with alternating current. For each defibrillation pulse, voltage, current, resistance and delivered energy were recorded. Of the 21 patients, 15 (71%) had a lower defibrillation threshold when the LV electrode was positive, 2 patients (10%) had a lower defibrillation threshold when the LV electrode was negative and 4 patients (19%) had equal defibrillation thresholds (within 0.5 J) regardless of polarity. The mean leading edge defibrillation threshold voltage was 370 +/- 88 volts when the LV electrode was negative and 320 +/- 109 volts (14% less) when the LV electrode was positive (p = 0.014). Mean leading edge defibrillation threshold current was 9.3 +/- 3.1 amps when the LV electrode was negative compared to 7.7 +/- 3.1 amps (17% less) when the LV electrode was positive (p = 0.0033). There were no differences in resistance with the 2 configurations.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Enhancement of dielectrophoresis using fractal gold nanostructured electrodes.

    PubMed

    Koklu, Anil; Sabuncu, Ahmet C; Beskok, Ali

    2017-06-01

    Dielectrophoretic motions of Saccharomyces cerevisiae (yeast) cells and colloidal gold are investigated using electrochemically modified electrodes exhibiting fractal topology. Electrodeposition of gold on electrodes generated repeated patterns with a fern-leaf type self-similarity. A particle tracking algorithm is used to extract dielectrophoretic particle velocities using fractal and planar electrodes in two different medium conductivities. The results show increased dielectrophoretic force when using fractal electrodes. Strong negative dielectrophoresis of yeast cells in high-conductivity media (1.5 S/m) is observed using fractal electrodes, while no significant motion is present using planar electrodes. Electrical impedance at the electrode/electrolyte interface is measured using impedance spectroscopy technique. Stronger electrode polarization (EP) effects are reported for planar electrodes. Decreased EP in fractal electrodes is considered as a reason for enhanced dielectrophoretic response. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Unitary plate electrode

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor); Clough, Thomas J. (Inventor); Josefowicz, Jack Y. (Inventor); Sibert, John W. (Inventor)

    1985-01-01

    The unitary electrode (10) comprises a porous sheet (12) of fiberglass the strands (14) of which contain a coating (16) of conductive tin oxide. The lower portion of the sheet contains a layer (18) of resin and the upper layer (20) contains lead dioxide forming a positive active electrode on an electrolyte-impervious layer. The strands (14) form a continuous conduction path through both layers (16, 18). Tin oxide is prevented from reduction by coating the surface of the plate facing the negative electrode with a conductive, impervious layer resistant to reduction such as a thin film (130) of lead or graphite filled resin adhered to the plate with a layer (31) of conductive adhesive. The plate (10) can be formed by casting a molten resin from kettle (60) onto a sheet of glass wool (56) overlying a sheet of lead foil and then applying positive active paste from hopper (64) into the upper layer (68). The plate can also be formed by passing an assembly of a sheet ( 80) of resin, a sheet (86) of sintered glass and a sheet (90) of lead between the nip (92) of heated rollers (93, 95) and then filling lead oxide into the pores (116) of the upper layer (118).

  19. Layered P3-NaxCo1/3Ni1/3Mn1/3O2 versus Spinel Li4Ti5O12 as a Positive and a Negative Electrode in a Full Sodium-Lithium Cell.

    PubMed

    Ivanova, Svetlana; Zhecheva, Ekaterina; Kukeva, Rositsa; Nihtianova, Diana; Mihaylov, Lyuben; Atanasova, Genoveva; Stoyanova, Radostina

    2016-07-13

    The development of lithium and sodium ion batteries without using lithium and sodium metal as anodes gives the impetus for elaboration of low-cost and environmentally friendly energy storage devices. In this contribution we demonstrate the design and construction of a new type of hybrid sodium-lithium ion cell by using unique electrode combination (Li4Ti5O12 spinel as a negative electrode and layered Na3/4Co1/3Ni1/3Mn1/3O2 as a positive electrode) and conventional lithium electrolyte (LiPF6 salt dissolved in EC/DMC). The cell operates at an average potential of 2.35 V by delivering a reversible capacity of about 100 mAh/g. The mechanism of the electrochemical reaction in the full sodium-lithium ion cell is studied by means of postmortem analysis, as well as ex situ X-ray diffraction analysis, HR-TEM, and electron paramagnetic resonance spectroscopy (EPR). The changes in the surface composition of electrodes are examined by ex situ X-ray photoelectron spectroscopy (XPS).

  20. Lithium-aluminum-iron electrode composition

    DOEpatents

    Kaun, Thomas D.

    1979-01-01

    A negative electrode composition is presented for use in a secondary electrochemical cell. The cell also includes an electrolyte with lithium ions such as a molten salt of alkali metal halides or alkaline earth metal halides that can be used in high-temperature cells. The cell's positive electrode contains a a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent in an alloy of aluminum-iron. Various binary and ternary intermetallic phases of lithium, aluminum and iron are formed. The lithium within the intermetallic phase of Al.sub.5 Fe.sub.2 exhibits increased activity over that of lithium within a lithium-aluminum alloy to provide an increased cell potential of up to about 0.25 volt.

  1. Fabrication of a 3 dimensional dielectrophoresis electrode by a metal inkjet printing method

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hyun; Yun, Gyu-Young; Koh, Yul; Lee, Sang-Ho; Kim, Yong-Kweon

    2013-12-01

    We proposed a micro electrode fabrication method by a metal inkjet printing technology for the bio-applications of dielectrophoresis (DEP). The electrodes are composed of bottom planar gold (Au) electrodes and three dimensional (3D) silver (Ag) electrodes fabricated locally on the Au electrode through metal inkjet printing. We observed the negative DEP characteristics of the 4 μm polystyrene beads on the both electrodes at the 500 kHz, AC 20 Vpp point. The number of beads trapped on the printed Ag electrode is 79 and 25 on the planar Au electrode because of spatially larger electric field in a 3D electrode system.

  2. Use of platinum electrodes for the electrochemical detection of bacteria

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.

    1978-01-01

    Platinum electrodes with surface area ratios of four to one were used to detect and enumerate a variety of gram-positive and gram-negative organisms. Linear relationships were established between inoculum size and detection time. End points for platinum electrodes were similar to those obtained with a platinum-reference electrode combination. Shape of the overall response curves and length of detection times for gram-positive organisms were markedly different than those for the majority of gram-negative species. Platinum electrodes are better than the platinum-reference electrode combination because of cost, ease of handling, and clearer definition of the end point.

  3. Use of platinum electrodes for the electrochemical detection of bacteria

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.

    1978-01-01

    Platinum electrodes with surface area ratios of four to one were used to detect and enumerate a variety of gram-positive and gram-negative organisms. Linear relationships were established between inoculum size and detection time. End points for platinum electrodes were similar to those obtained with a platinum-reference electrode combination. Shape of the overall response curves and length of detection times for gram-positive organisms were markedly different than those for the majority of gram-negative species. Platinum electrodes are better than the platinum-reference electrode combination because of cost, ease of handling, and clearer definition of the end point.

  4. resterilizable electrode for electrosurgery

    NASA Technical Reports Server (NTRS)

    Engstrom, E. R.; Houge, J. C.

    1979-01-01

    Required properties of flexibility, electrical conductivity, tensile strength, and tear resistance of electrosurgical electrodes is retained through utilization of flexible-polymer/conductive particle composites for electrodes.

  5. Considerations for Estimating Electrode Performance in Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Bennett, William R.

    2012-01-01

    Advanced electrode materials with increased specific capacity and voltage performance are critical to the development of Li-ion batteries with increased specific energy and energy density. Although performance metrics for individual electrodes are critically important, a fundamental understanding of the interactions of electrodes in a full cell is essential to achieving the desired performance, and for establishing meaningful goals for electrode performance. This paper presents practical design considerations for matching positive and negative electrodes in a viable design. Methods for predicting cell-level discharge voltage, based on laboratory data for individual electrodes, are presented and discussed.

  6. Improved lithium-ion battery performance of LiNi0.5Mn1.5-xTixO4 high voltage spinel in full-cells paired with graphite and Li4Ti5O12 negative electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Hyun; Pieczonka, Nicholas P. W.; Sun, Yang-Kook; Powell, Bob R.

    2014-09-01

    The effect of Ti-substitution on the electrochemical properties of LiNi0.5Mn1.5-xTixO4 was investigated by using half-cells paired with lithium metal, and full-cells paired with either graphite or Li4Ti5O12 (LTO) negative electrodes. In half-cells, Ti-substitution increased the operation voltage, but reduced the specific capacity. While some improvements in performance, such as higher operation voltage and less self-discharge, could be measured in the half-cells, the critical advantages of the Ti-substitution were readily observed in full-cell cycling. Compared with Ti-free LiNi0.5Mn1.5O4, the LiNi0.5Mn1.5-xTixO4 electrodes delivered improved full-cell performance whether paired with graphite or LTO negative electrodes; greater cycle life, higher cell operating voltage, and lower voltage polarization on charging/discharging. Based on relatively low self-discharge and high Coulombic efficiency, it is suggested that the Ti-substitution in LiNi0.5Mn1.5-xTixO4 retards electrolyte oxidation. In addition, scanning electron microscopy (SEM) images revealed that cycle-aged LiNi0.5Mn1.2Ti0.3O4 particle surfaces remained relatively clean compared with those of LiNi0.5Mn1.5O4 particles. These results are consistent with the hypothesis that Ti-substitution reduces electrolyte oxidation and retards or prevents some of the degradative parasitic reactions at the electrode/electrolyte interfaces during battery cell operation.

  7. A synchrotron x-ray diffraction and hard x-ray photoelectron spectroscopy study of Zn negative electrodes at different charge and discharge states of Zn/MnO2 batteries using an ionic liquid-based gel polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Abad, José; Santos, Florencio; Tafur, Juan P.; Urbina, Antonio; Román, Elisa; González-Martínez, J. F.; Rubio-Zuazo, J.; Castro, G. R.; Fernández Romero, Antonio J.

    2017-09-01

    Zn/MnO2 batteries including an ionic liquid-based gel polymer electrolyte (IL-GPE) have been discharged or discharged and then recharged reaching different states of charge. The Zn electrodes used in these Zn/MnO2 batteries are studied by HAXPES and synchrotron XRD techniques. Besides, HAXPES measurements are compared with the results obtained by a conventional XPS. Formation of Zn(OH)2 and ZnO is found in intermediate states of charge during charging and discharging. However, only ZnO is observed in the anode when a full discharging was carried out. Conversely, an entire charging process produces a complete reduction of all Zn2+ species to metallic Zn. In addition, various techniques have confirmed the entrance of Triflate anions and NMP solvent molecules in the electrode, accompanying the Zn2+ cations movement during the charging.

  8. Ion-Selective Electrodes.

    ERIC Educational Resources Information Center

    Arnold, Mark A.; Meyerhoff, Mark E.

    1984-01-01

    Literature on ion-selective electrodes (ISEs) is reviewed in seven sections: books, conferences, reviews; potentiometric membrane electrodes; glass and solid-state membrane electrodes; liquid and polymer membrane ISEs; coated wire electrodes, ion-selective field effect transistors, and microelectrodes; gas sensors and selective bioelectrode…

  9. Ion-Selective Electrodes.

    ERIC Educational Resources Information Center

    Arnold, Mark A.; Meyerhoff, Mark E.

    1984-01-01

    Literature on ion-selective electrodes (ISEs) is reviewed in seven sections: books, conferences, reviews; potentiometric membrane electrodes; glass and solid-state membrane electrodes; liquid and polymer membrane ISEs; coated wire electrodes, ion-selective field effect transistors, and microelectrodes; gas sensors and selective bioelectrode…

  10. 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.

  11. Dan Johnson the mentor

    NASA Astrophysics Data System (ADS)

    McKinley, Richard

    2003-04-01

    I first met Dan Johnson in early 1975 as I was interviewing for an engineering job with Henning von Gierke's bioengineering and bionics laboratory at Wright-Patterson Air Force Base. From the very beginning Dan was always direct and forthright. Over the ensuing next 27 years my knowledge and respect of Dan constantly grew. This presentation will review Dan's technical and personal contributions while at the laboratory at Wright-Patterson Air Force Base. He was instrumental in the development of a national noise exposure criteria with the equal-energy-rule, an accurate single number hearing protector attenuation measure based on ``C-A,'' an impulse noise exposure criteria, a longitudinal study of hearing loss in children, development of noise dosimeters, and description of hearing damage risk from nonoccupational noise exposures such as disco's, bowling alleys, lawn mowers, and school buses. Dan has had a significant effect on my career. I and the many people who knew him at the laboratory miss him greatly.

  12. Li-alloy electrode for Li-alloy/metal sulfide cells

    DOEpatents

    Kaun, T.D.

    1996-07-16

    A method of making a negative electrode is described, the electrode made thereby and a secondary electrochemical cell using the electrode. Lithium, silicon and nickel is alloyed in a prescribed proportion forming an electroactive material, to provide an improved electrode and cell. 7 figs.

  13. Controlled porosity in electrodes

    DOEpatents

    Chiang, Yet-Ming; Bae, Chang-Jun; Halloran, John William; Fu, Qiang; Tomsia, Antoni P.; Erdonmez, Can K.

    2015-06-23

    Porous electrodes in which the porosity has a low tortuosity are generally provided. In some embodiments, the porous electrodes can be designed to be filled with electrolyte and used in batteries, and can include low tortuosity in the primary direction of ion transport during charge and discharge of the battery. In some embodiments, the electrodes can have a high volume fraction of electrode active material (i.e., low porosity). The attributes outlined above can allow the electrodes to be fabricated with a higher energy density, higher capacity per unit area of electrode (mAh/cm.sup.2), and greater thickness than comparable electrodes while still providing high utilization of the active material in the battery during use. Accordingly, the electrodes can be used to produce batteries with high energy densities, high power, or both compared to batteries using electrodes of conventional design with relatively highly tortuous pores.

  14. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  15. High frequency reference electrode

    DOEpatents

    Kronberg, James W.

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  16. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  17. Micromachined electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.

    2007-12-11

    An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

  18. High performance cermet electrodes

    DOEpatents

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

  19. Redox polymer electrodes for advanced batteries

    DOEpatents

    Gregg, Brian A.; Taylor, A. Michael

    1998-01-01

    Advanced batteries having a long cycle lifetime are provided. More specifically, the present invention relates to electrodes made from redox polymer films and batteries in which either the positive electrode, the negative electrode, or both, comprise redox polymers. Suitable redox polymers for this purpose include pyridyl or polypyridyl complexes of transition metals like iron, ruthenium, osmium, chromium, tungsten and nickel; porphyrins (either free base or metallo derivatives); phthalocyanines (either free base or metallo derivatives); metal complexes of cyclams, such as tetraazacyclotetradecane; metal complexes of crown ethers and metallocenes such as ferrocene, cobaltocene and ruthenocene.

  20. Redox polymer electrodes for advanced batteries

    DOEpatents

    Gregg, B.A.; Taylor, A.M.

    1998-11-24

    Advanced batteries having a long cycle lifetime are provided. More specifically, the present invention relates to electrodes made from redox polymer films and batteries in which either the positive electrode, the negative electrode, or both, comprise redox polymers. Suitable redox polymers for this purpose include pyridyl or polypyridyl complexes of transition metals like iron, ruthenium, osmium, chromium, tungsten and nickel; porphyrins (either free base or metallo derivatives); phthalocyanines (either free base or metallo derivatives); metal complexes of cyclams, such as tetraazacyclotetradecane; metal complexes of crown ethers and metallocenes such as ferrocene, cobaltocene and ruthenocene. 2 figs.

  1. Electronically conductive polymer binder for lithium-ion battery electrode

    DOEpatents

    Liu, Gao; Xun, Shidi; Battaglia, Vincent S; Zheng, Honghe

    2014-10-07

    A family of carboxylic acid group containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

  2. Electronically conductive polymer binder for lithium-ion battery electrode

    DOEpatents

    Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe

    2017-05-16

    A family of carboxylic acid group containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

  3. Corneal-shaping electrode

    DOEpatents

    Doss, James D.; Hutson, Richard L.

    1982-01-01

    The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.

  4. Which Disposable Chest Electrode?

    PubMed Central

    Hubner, P. J. B.

    1969-01-01

    Chest electrodes are preferred to limb electrodes for cardiac monitoring, as limb movements are not restricted and produce less interference of the E.C.G. trace. Eight types of disposable chest electrodes were investigated to compare their performance, skin reactions, cost, ease of application, size, and skin–electrode impedance. Elema-Schonander electrodes were found to be the most efficient and the most expensive. In their application care was required to avoid severe skin reactions. Dracard electrodes were simple to attach, worked well without severe skin reactions, and were cheap. They are recommended for routine use. Smith and Nephew electrodes, a type of “multipoint electrodes” which do not require electrode jelly, frequently produced severe skin reactions, making them unsuitable for monitoring for periods exceeding 12 hours. PMID:5801347

  5. Corrugated battery electrode

    NASA Technical Reports Server (NTRS)

    Mccallum, J.

    1974-01-01

    Performance of porous electrodes in batteries and other electrochemical cells is greatly improved when supports for active material have pores of uniform size, extending completely through electrodes, from side to side, with no interconnections between pores.

  6. FUEL CELL ELECTRODE MATERIALS

    DTIC Science & Technology

    FUEL CELL ELECTRODE MATERIALS. RAW MATERIAL SELECTION INFLUENCES POLARIZATION BUT IS NOT A SINGLE CONTROLLING FACTOR. AVAILABLE...DATA INDICATES THAT AN INTERRELATIONSHIP OF POROSITY, AVERAGE PORE VOLUME, AND PERMEABILITY CONTRIBUTES TO ELECTRODE FUEL CELL BEHAVIOR.

  7. Improved biomedical electrode

    NASA Technical Reports Server (NTRS)

    Frost, J. D., Jr.

    1972-01-01

    Newly designed electrode is prefilled, disposable, electrolyte-saturated spong. New design permits longe periods of storage without deterioration, and readiness in matter of seconds. Electrodes supply signals for electroencephalogram, electro-oculogram, and electrocardiogram.

  8. The CMG Nickel Electrode

    NASA Technical Reports Server (NTRS)

    Depaul, R. A.; Gutridge, I.

    1981-01-01

    The development and design of the Controlled Microgeometry electrode are described. Advantages of the electrode over others in existance include a higher number of ampere hours per kilogram and the ability to make them over a wide range of thicknesses. The parameters that control the performance of the electrode can be individually controlled over a wide range. Therefore, the electrode may be designed to give the optimum performance for a given duty cycle.

  9. Compartmented electrode structure

    DOEpatents

    Vissers, Donald R.; Shimotake, Hiroshi; Gay, Eddie C.; Martino, Fredric J.

    1977-06-14

    Electrodes for secondary electrochemical cells are provided with compartments for containing particles of the electrode reactant. The compartments are defined by partitions that are generally impenetrable to the particles of reactant and, in some instances, to the liquid electrolyte used in the cell. During cycling of the cell, reactant material initially loaded into a particular compartment is prevented from migrating and concentrating within the lower portion of the electrode or those portions of the electrode that exhibit reduced electrical resistance.

  10. Low resistance fuel electrodes

    DOEpatents

    Maskalick, Nichols J.; Folser, George R.

    1989-01-01

    An electrode 6 bonded to a solid, ion conducting electrolyte 5 is made, where the electrode 6 comprises a ceramic metal oxide 18, metal particles 17, and heat stable metal fibers 19, where the metal fibers provide a matrix structure for the electrode. The electrolyte 5 can be bonded to an air electrode cathode 4, to provide an electrochemical cell 2, preferably of tubular design.

  11. Advanced screening of electrode couples

    NASA Technical Reports Server (NTRS)

    Giner, J. D.; Cahill, K.

    1980-01-01

    The chromium (Cr(3+)/Cr(2+)) redox couple (electrolyte and electrode) was investigated to determine its suitability as negative electrode for the iron (Fe(3+)/Fe(2+))-chromium (Cr(3+)/Cr(2+)) redox flow battery. Literature search and laboratory investigation established that the solubility and stability of aqueous acidic solutions of chromium(3) chloride and chromium(2) chloride are sufficient for redox battery application. Four categories of electrode materials were tested; namely, metals and metalloid materials (elements and compounds), alloys, plated materials, and Teflon-bonded materials. In all, the relative performance of 26 candidate electrode materials was evaluated on the basis of slow scan rate linear sweep voltammetry in stirred solution. No single material tested gave both acceptable anodic an acceptable cathodic performance. However, the identification of lead as a good cathodic electrocatalyst and gold as a good anodic electrocatalyst led to the invention of the lead/gold combination electrocatalyst. This type of catalyst can be fabricated in several ways and appears to offer the advantages of each metal without the disadvantages associated with their use as single materials. This lead/gold electrocatalyst was tested by NASA-Lewis Research Center in complete, flowing, redox batteries comprising a stack of several cells. A large improvement in the battery's coulombic and energy efficiency was observed.

  12. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg [East Lansing, MI; Fischer, Anne [Arlington, VA; Bennett, Jason [Lansing, MI; Lowe, Michael [Holt, MI

    2009-05-19

    An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

  13. Aerospace electrode line

    NASA Astrophysics Data System (ADS)

    Miller, L.

    1980-04-01

    A facility which produces electrodes for spacecraft power supplies is described. The electrode assembly procedures are discussed. A number of design features in the production process are reported including a batch operation mode and an independent equipment module design approach for transfering the electrode materials from process tank to process tank.

  14. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  15. Insulated ECG electrodes

    NASA Technical Reports Server (NTRS)

    Portnoy, W. M.; David, R. M.

    1973-01-01

    Insulated, capacitively coupled electrode does not require electrolyte paste for attachment. Other features of electrode include wide range of nontoxic material that may be employed for dielectric because of sputtering technique used. Also, electrode size is reduced because there is no need for external compensating networks with FET operational amplifier.

  16. Fuel cell electrodes

    DOEpatents

    Strmcnik, Dusan; Cuesta, Angel; Stamenkovic, Vojislav; Markovic, Nenad

    2015-06-23

    A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

  17. A Simple Hydrogen Electrode

    ERIC Educational Resources Information Center

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  18. A Simple Hydrogen Electrode

    ERIC Educational Resources Information Center

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  19. Microresonator electrode design

    DOEpatents

    Olsson, III, Roy H.; Wojciechowski, Kenneth; Branch, Darren W.

    2016-05-10

    A microresonator with an input electrode and an output electrode patterned thereon is described. The input electrode includes a series of stubs that are configured to isolate acoustic waves, such that the waves are not reflected into the microresonator. Such design results in reduction of spurious modes corresponding to the microresonator.

  20. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  1. Damage cost of the Dan River coal ash spill

    Treesearch

    A. Dennis Lemly

    2015-01-01

    The recent coal ash spill on the Dan River in North Carolina, USA has caused several negative effects on the environment and the public. In this analysis, I report a monetized value for these effects after the first 6 months following the spill. The combined cost of ecological damage, recreational impacts, effects on human health and consumptive use, and esthetic value...

  2. Igniter electrode life control

    SciTech Connect

    Scott, J.C.

    1985-10-07

    The prevention of electrode material erosion by undercutting in the outer electrode shell of igniter electrodes of jet engine ignition systems is prevented by the application of an electrical insulation coating. The coating is applied to the surface of the outer electrode shell which faces the ceramic insulation around the center electrode where erosion patterns are known to occur. The insulation material is selected from electrical insulation substances such as oxides of aluminum, tungsten, magnesium, beryllium or zirconium by choosing a non-porous electrical-insulating substance with thermal-expansion characteristics approximately equalling those of the outer electrode shell. Since a typical outer electrode shell is composed of 446 stainless steel, an optimum choice for the electrical insulation coating is Al/sub 2/O/sub 3/ deposited with a coating thickness of between 5 and 10 mils.

  3. Nanodisperse transition metal electrodes (NTME) for electrochemical cells

    SciTech Connect

    Striebel, Kathryn A.; Wen, Shi-Jie

    1998-12-01

    Disclosed are transition metal electrodes for electrochemical cells using gel-state and solid-state polymers. The electrodes are suitable for use in primary and secondary cells. The electrodes (either negative electrode or positive electrode) are characterized by uniform dispersion of the transition metal at the nanoscale in the polymer. The transition metal moiety is structurally amorphous, so no capacity fade should occur due to lattice expansion/contraction mechanisms. The small grain size, amorphous structure and homogeneous distribution provide improved charge/discharge cycling performance, and a higher initial discharge rate capability. The cells can be cycled at high current densities, limited only by the electrolyte conductivity. A method of making the electrodes (positive and negative), and their usage in electrochemical cells are disclosed.

  4. Nanodisperse transition metal electrodes (NTME) for electrochemical cells

    DOEpatents

    Striebel, Kathryn A.; Wen, Shi-Jie

    2000-01-01

    Disclosed are transition metal electrodes for electrochemical cells using gel-state and solid-state polymers. The electrodes are suitable for use in primary and secondary cells. The electrodes (either negative electrode or positive electrode) are characterized by uniform dispersion of the transition metal at the nanoscale in the polymer. The transition metal moiety is structurally amorphous, so no capacity fade should occur due to lattice expansion/contraction mechanisms. The small grain size, amorphous structure and homogeneous distribution provide improved charge/discharge cycling performance, and a higher initial discharge rate capability. The cells can be cycled at high current densities, limited only by the electrolyte conductivity. A method of making the electrodes (positive and negative), and their usage in electrochemical cells are disclosed.

  5. Thai Negation.

    ERIC Educational Resources Information Center

    Alam, Samsul

    A study analyzed the structure of negative sentences in the Thai language, based on data gathered from two native speakers. It is shown that the Thai negative marker generally occurs between the noun phrase (subject) and the verb phrase in simple active sentences and in passive sentences. Negation of noun phrases is also allowed in Thai, with a…

  6. Virtual electrode effects in myocardial fibers.

    PubMed Central

    Knisley, S B; Hill, B C; Ideker, R E

    1994-01-01

    The changes in transmembrane potential during a stimulation pulse in the heart are not known. We have used transmembrane potential sensitive dye fluorescence to measure changes in transmembrane potential along fibers in an anisotropic arterially perfused rabbit epicardial layer. Cathodal or anodal extracellular point stimulation produced changes in transmembrane potential within 60 microns of the electrode that were positive or negative, respectively. The changes in transmembrane potential did not simply decrease to zero with increasing distance, as would occur with a theoretical fiber space constant, but instead became reversed beyond approximately 1 mm from the electrode consistent with a virtual electrode effect. Even stimulation from a line of terminals perpendicular to the fibers produced negative changes in transmembrane potential for cathodal stimulation with the largest negative changes during a 50-ms pulse at 3-4 mm from the electrode terminals. Negative changes as large as the amplitude of the action potential rising phase occurred during a 50-ms pulse for 20-volt cathodal stimulation. Switching to anodal stimulation reversed the directions of changes in transmembrane potential at most recording spots, however for stimulation during the refractory period negative changes in transmembrane potential were significantly larger than positive changes in transmembrane potential. Anodal stimulation during diastole with 3-ms pulses produced excitation in the region of depolarization that accelerated when the stimulation strength was increased to > 3 times the anodal threshold strength. Thus, virtual electrode effects of unipolar stimulation occur in myocardial fibers, and for sufficiently strong stimuli the virtual electrode effects may influence electrical behavior of the myocardium. PMID:8011903

  7. 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.

  8. The cadmium electrode: Review of the status of research

    NASA Technical Reports Server (NTRS)

    Gross, S.; Glockling, R. J.

    1976-01-01

    Investigations characterizing the negative cadmium electrode used in a nickel cadmium battery cell are summarized with citations to references where more detailed information is available. Emphasis is placed on data pertinent to aerospace applications. An evaluation of some of the published results of cadmium electrode research is included.

  9. Nongassing nickel-cadmium battery electrodes and cells

    NASA Technical Reports Server (NTRS)

    Luksha, E.; Gordy, D. J.

    1972-01-01

    The failure of nickel-cadmium storage batteries due to severe gassing during charging is discussed. In order to increase the life of such cells, nongassing positive and negative electrodes are used. The gassing characteristics of nickel electrodes were evaluated as a function of their loading, charge rate, and charge temperature.

  10. Bifunctional alkaline oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  11. Nanoscopic electrode molecular probes

    DOEpatents

    Krstic, Predrag S [Knoxville, TN; Meunier, Vincent [Knoxville, TN

    2012-05-22

    The present invention relates to a method and apparatus for enhancing the electron transport property measurements of a molecule when the molecule is placed between chemically functionalized carbon-based nanoscopic electrodes to which a suitable voltage bias is applied. The invention includes selecting a dopant atom for the nanoscopic electrodes, the dopant atoms being chemically similar to atoms present in the molecule, and functionalizing the outer surface and terminations of the electrodes with the dopant atoms.

  12. MALDI-MS analysis and imaging of small molecule metabolites with 1,5-diaminonaphthalene (DAN)

    SciTech Connect

    Korte, Andrew R; Lee, Young Jin

    2014-07-08

    1,5-diaminonaphthalene (DAN) has previously been reported as an effective matrix for matrix-assisted laser desorption ionization-mass spectrometry of phospholipids. In the current work, we investigate the use of DAN as a matrix for small metabolite analysis in negative ion mode. DAN was found to provide superior ionization to the compared matrices for MW < ~400 Da; however, 9-aminoacridine (9-AA) was found to be superior for a uridine diphosphate standard (MW 566 Da). DAN was also found to provide a more representative profile of a natural phospholipid mixture than 9-AA. Finally, DAN and 9-AA were applied for imaging of metabolites directly from corn leaf sections. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  13. Pocket ECG electrode

    NASA Technical Reports Server (NTRS)

    Lund, Gordon F. (Inventor)

    1982-01-01

    A low-noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free-ranging subject. The electrode comprises a pocket-shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

  14. Pocket ECG electrode

    NASA Technical Reports Server (NTRS)

    Lund, G. F. (Inventor)

    1980-01-01

    A low noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free ranging subject is described. The electrode comprises a pocket shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member, remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

  15. Negative hydrogen ion production mechanisms

    SciTech Connect

    Bacal, M.; Wada, M.

    2015-06-15

    Negative hydrogen/deuterium ions can be formed by processes occurring in the plasma volume and on surfaces facing the plasma. The principal mechanisms leading to the formation of these negative ions are dissociative electron attachment to ro-vibrationally excited hydrogen/deuterium molecules when the reaction takes place in the plasma volume, and the direct electron transfer from the low work function metal surface to the hydrogen/deuterium atoms when formation occurs on the surface. The existing theoretical models and reported experimental results on these two mechanisms are summarized. Performance of the negative hydrogen/deuterium ion sources that emerged from studies of these mechanisms is reviewed. Contemporary negative ion sources do not have negative ion production electrodes of original surface type sources but are operated with caesium with their structures nearly identical to volume production type sources. Reasons for enhanced negative ion current due to caesium addition to these sources are discussed.

  16. Negative hydrogen ion production mechanisms

    NASA Astrophysics Data System (ADS)

    Bacal, M.; Wada, M.

    2015-06-01

    Negative hydrogen/deuterium ions can be formed by processes occurring in the plasma volume and on surfaces facing the plasma. The principal mechanisms leading to the formation of these negative ions are dissociative electron attachment to ro-vibrationally excited hydrogen/deuterium molecules when the reaction takes place in the plasma volume, and the direct electron transfer from the low work function metal surface to the hydrogen/deuterium atoms when formation occurs on the surface. The existing theoretical models and reported experimental results on these two mechanisms are summarized. Performance of the negative hydrogen/deuterium ion sources that emerged from studies of these mechanisms is reviewed. Contemporary negative ion sources do not have negative ion production electrodes of original surface type sources but are operated with caesium with their structures nearly identical to volume production type sources. Reasons for enhanced negative ion current due to caesium addition to these sources are discussed.

  17. Energy storage systems having an electrode comprising Li.sub.xS.sub.y

    SciTech Connect

    Xiao, Jie; Zhang, Jiguang; Graff, Gordon L.; Liu, Jun; Wang, Wei; Zheng, Jianming; Xu, Wu; Shao, Yuyan; Yang, Zhenguo

    2016-08-02

    Improved lithium-sulfur energy storage systems can utilizes Li.sub.xS.sub.y as a component in an electrode of the system. For example, the energy storage system can include a first electrode current collector, a second electrode current collector, and an ion-permeable separator separating the first and second electrode current collectors. A second electrode is arranged between the second electrode current collector and the separator. A first electrode is arranged between the first electrode current collector and the separator and comprises a first condensed-phase fluid comprising Li.sub.xS.sub.y. The energy storage system can be arranged such that the first electrode functions as a positive or a negative electrode.

  18. Non-gassing nickel-cadmium battery electrodes and cells

    NASA Technical Reports Server (NTRS)

    Luksha, E.; Gordy, D. J.

    1972-01-01

    Supposedly long-lived nickel-cadmium batteries often fail due to severe gassing on charge. In order to increase the lives of such cells attempts are being made to construct nongassing positive and negative electrodes. The gassing characteristics of both electrodes in negative limited cells were determined as a function of charge rate, charge temperature, and loading. Cycle life tests, up to 70 cycles, of some of the cells show they operate in a nongassing manner with very low degradation rates.

  19. Electrode stabilizing materials

    DOEpatents

    Amine, Khalil; Abouimrane, Ali; Moore, Jeffrey S.; Odom, Susan A.

    2015-11-03

    An electrolyte includes a polar aprotic solvent; an alkali metal salt; and an electrode stabilizing compound that is a monomer, which when polymerized forms an electrically conductive polymer. The electrode stabilizing compound is a thiophene, a imidazole, a anilines, a benzene, a azulene, a carbazole, or a thiol. Electrochemical devices may incorporate such electrolytes.

  20. Long term flight electrodes

    NASA Technical Reports Server (NTRS)

    Mosier, B.

    1975-01-01

    The reproducibility, stability, and methods of preparation for the various types and forms of biomedical electrodes are discussed. A critical and selective compilation of information on biological and/or physiological electrodes is presented. A discussion of plant hydrocolloids, clays, hydrophyllic colloids, synthetic waxes, and acrylic polymers is included.

  1. Amperometric Enzyme Electrodes

    DTIC Science & Technology

    1989-12-01

    and C. Lyons. "Electrode systems for continuous monitoring in cardiomuscula murgery," Ann. NY Acad. Sci.. 102 (1962). 20-45. [6]. 1. J. Updike mid G...Chemistry, John Wiley & Sons: New York (1980). 197-236. [2]. L D. Mell and J. T. Maloy, "A Model for the Amperometric Enzyme Electrode Obtained through

  2. Membrane Bioprobe Electrodes

    ERIC Educational Resources Information Center

    Rechnitz, Garry A.

    1975-01-01

    Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

  3. Membrane Bioprobe Electrodes

    ERIC Educational Resources Information Center

    Rechnitz, Garry A.

    1975-01-01

    Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

  4. Electrolysis-reducing electrodes for electrokinetic devices.

    PubMed

    Erlandsson, Per G; Robinson, Nathaniel D

    2011-03-01

    Direct current electrokinetic systems generally require Faradaic reactions to occur at a pair of electrodes to maintain an electric field in an electrolyte connecting them. The vast majority of such systems, e.g. electrophoretic separations (capillary electrophoresis) or electroosmotic pumps (EOPs), employ electrolysis of the solvent in these reactions. In many cases, the electrolytic products, such as H+ and OH⁻ in the case of water, can negatively influence the chemical or biological species being transported or separated, and gaseous products such as O₂ and H₂ can break the electrochemical circuit in microfluidic devices. This article presents an EOP that employs the oxidation/reduction of the conjugated polymer poly(3,4-ethylenedioxythiophene), rather than electrolysis of a solvent, to drive flow in a capillary. Devices made with poly(3,4-ethylenedioxythiophene) electrodes are compared with devices made with Pt electrodes in terms of flow and local pH change at the electrodes. Furthermore, we demonstrate that flow is driven for applied potentials under 2 V, and the electrodes are stable for potentials of at least 100 V. Electrochemically active electrodes like those presented here minimize the disadvantage of integrated EOP in, e.g. lab-on-a-chip applications, and may open new possibilities, especially for battery-powered disposable point-of-care devices. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Bifunctional catalytic electrode

    NASA Technical Reports Server (NTRS)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  6. Uphill transport membrane electrodes

    SciTech Connect

    Uto, M.; Yoshida, H.; Sugawara, M.; Umezawa, Y.

    1986-07-01

    A new membrane electrode was constructed in which carrier-mediated uphill transport of analytes is incorporated. The electrode can boost selectively virtual concentration of specific analytes by uphill transport against their concentration gradient across a built-in liquid membrane into its inner filling solution, whose volume is purposely made very small. Cd(II), UO/sub 2//sup 2 +/, and Cu(II) ion uphill transport membrane electrodes constructed here as illustrative examples utilize three different types of input energies, i.e., complexation, concentration gradient, and redox, respectively, for uphill transport of each analyte. Voltammetric detections were demonstrated for Cd(II) and UO/sub 2//sup 2 +/ ion uphill transport electrodes, and a potentiometric detection for a Cu(II) ion uphill transport membrane electrode is also described in terms of fundamental behaviors and a possible use for a new type of electrochemical sensor.

  7. Electrodes for microfluidic applications

    DOEpatents

    Crocker, Robert W.; Harnett, Cindy K.; Rognlien, Judith L.

    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.

  8. Optimization and fabrication of porous carbon electrodes for Fe/Cr redox flow calls

    NASA Astrophysics Data System (ADS)

    Jalan, V.; Morriseau, B.; Swette, L.

    1982-07-01

    Negative electrode development for the NASA chromous/ferric Redox battery is reported. The effects of substrate material, gold/lead catalyst composition and loading, and catalyzation procedures on the performance of the chromium electrode were investigated. Three alternative catalyst systems were also examined, and 1/3 square foot size electrodes were fabricated and delivered to NASA at the conclusion of the program.

  9. Bacterial and fungal killing by iontophoresis with long-lived electrodes.

    PubMed Central

    Davis, C P; Wagle, N; Anderson, M D; Warren, M M

    1991-01-01

    Iontophoresis with gold, carbon, and platinum electrodes was shown to effectively reduce or eliminate gram-positive, gram-negative, and Candida albicans inocula in synthetic urine. Platinum and gold electrodes were more effective than carbon electrodes, but platinum showed the best longevity and may reduce or eliminate microbial colonization of catheters. PMID:1759837

  10. Optimization and fabrication of porous carbon electrodes for Fe/Cr redox flow cells

    NASA Technical Reports Server (NTRS)

    Jalan, V.; Morriseau, B.; Swette, L.

    1982-01-01

    Negative electrode development for the NASA chromous/ferric Redox battery is reported. The effects of substrate material, gold/lead catalyst composition and loading, and catalyzation procedures on the performance of the chromium electrode were investigated. Three alternative catalyst systems were also examined, and 1/3 square foot size electrodes were fabricated and delivered to NASA at the conclusion of the program.

  11. Lithium electrode and an electrical energy storage device containing the same

    DOEpatents

    Lai, San-Cheng

    1976-07-13

    An improved lithium electrode structure comprises an alloy of lithium and silicon in specified proportions and a supporting current-collecting matrix in intimate contact with said alloy. The lithium electrode of the present invention is utilized as the negative electrode in a rechargeable electrochemical cell.

  12. Method of preparing a positive electrode for an electrochemical cell

    DOEpatents

    Tomczuk, Zygmunt

    1979-01-01

    A method of preparing an electrochemical cell including a metal sulfide as the positive electrode reactant and lithium alloy as the negative electrochemical reactant with an alkali metal, molten salt electrolyte is disclosed which permits the assembly to be accomplished in air. The electrode reactants are introduced in the most part as a sulfide of lithium and the positive electrode metal in a single-phase compound. For instance, Li.sub.2 FeS.sub.2 is a single-phase compound that is produced by the reaction of Li.sub.2 S and FeS. This compound is an intermediate in the positive electrode cycle from FeS.sub.2 to Fe and Li.sub.2 S. Its use minimizes volumetric changes from the assembled to the charged and discharged conditions of the electrode and minimizes electrode material interaction with air and moisture during assembly.

  13. Electrodes for sealed secondary batteries

    NASA Technical Reports Server (NTRS)

    Boies, D. B.; Child, F. T.

    1972-01-01

    Self-supporting membrane electrode structures, in which active ingredients and graphite are incorporated in a polymeric matrix, improve performance of electrodes in miniature, sealed, alkaline storage batteries.

  14. Layered electrode for electrochemical cells

    DOEpatents

    Swathirajan, Swathy; Mikhail, Youssef M.

    2001-01-01

    There is provided an electrode structure comprising a current collector sheet and first and second layers of electrode material. Together, the layers improve catalyst utilization and water management.

  15. Measuring electrode assembly

    DOEpatents

    Bordenick, John E.

    1989-01-01

    A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture.

  16. Measuring electrode assembly

    DOEpatents

    Bordenick, J.E.

    1988-04-26

    A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture. 2 figs.

  17. Electrode-electrolyte interface model of tripolar concentric ring electrode and electrode paste.

    PubMed

    Nasrollaholhosseini, Seyed Hadi; Steele, Preston; Besio, Walter G

    2016-08-01

    Electrodes are used to transform ionic currents to electrical currents in biological systems. Modeling the electrode-electrolyte interface could help to optimize the performance of the electrode interface to achieve higher signal to noise ratios. There are previous reports of accurate models for single-element biomedical electrodes. In this paper we develop a model for the electrode-electrolyte interface for tripolar concentric ring electrodes (TCRE) that are used to record brain signals.

  18. Multifunctional reference electrode

    DOEpatents

    Redey, L.; Vissers, D.R.

    1981-12-30

    A multifunctional, low mass reference electrode of a nickel tube, thermocouple means inside the nickel tube electrically insulated therefrom for measuring the temperature thereof, a housing surrounding the nickel tube, an electrolyte having a fixed sulfide ion activity between the housing and the outer surface of the nickel tube forming the nickel/nickel sulfide/sulfide half-cell are described. An ion diffusion barrier is associated with the housing in contact with the electrolyte. Also disclosed is a cell using the reference electrode to measure characteristics of a working electrode.

  19. Multifunctional reference electrode

    DOEpatents

    Redey, Laszlo; Vissers, Donald R.

    1983-01-01

    A multifunctional, low mass reference electrode of a nickel tube, thermocouple means inside the nickel tube electrically insulated therefrom for measuring the temperature thereof, a housing surrounding the nickel tube, an electrolyte having a fixed sulfide ion activity between the housing and the outer surface of the nickel tube forming the nickel/nickel sulfide/sulfide half-cell. An ion diffusion barrier is associated with the housing in contact with the electrolyte. Also disclosed is a cell using the reference electrode to measure characteristics of a working electrode.

  20. Operating a redox flow battery with a negative electrolyte imbalance

    DOEpatents

    Pham, Quoc; Chang, On; Durairaj, Sumitha

    2015-03-31

    Loss of flow battery electrode catalyst layers during self-discharge or charge reversal may be prevented by establishing and maintaining a negative electrolyte imbalance during at least parts of a flow battery's operation. Negative imbalance may be established and/or maintained actively, passively or both. Actively establishing a negative imbalance may involve detecting an imbalance that is less negative than a desired threshold, and processing one or both electrolytes until the imbalance reaches a desired negative level. Negative imbalance may be effectively established and maintained passively within a cell by constructing a cell with a negative electrode chamber that is larger than the cell's positive electrode chamber, thereby providing a larger quantity of negative electrolyte for reaction with positive electrolyte.

  1. Electrochemical cell having cylindrical electrode elements

    DOEpatents

    Nelson, Paul A.; Shimotake, Hiroshi

    1982-01-01

    A secondary, high temperature electrochemical cell especially adapted for lithium alloy negative electrodes, transition metal chalcogenide positive electrodes and alkali metal halide or alkaline earth metal halide electrolyte is disclosed. The cell is held within an elongated cylindrical container in which one of the active materials is filled around the outside surfaces of a plurality of perforate tubular current collectors along the length of the container. Each of the current collector tubes contain a concentric tubular layer of electrically insulative ceramic as an interelectrode separator. The active material of opposite polarity in elongated pin shape is positioned longitudinally within the separator layer. A second electrically conductive tube with perforate walls can be swagged or otherwise bonded to the outer surface of the pin as a current collector and the electrically insulative ceramic layer can be coated or otherwise layered onto the outer surface of this second current collector. Alternatively, the central pin electrode can include an axial core as a current collector.

  2. Layered electrodes for lithium cells and batteries

    DOEpatents

    Johnson; Christopher S. , Thackeray; Michael M. , Vaughey; John T. , Kahaian; Arthur J. , Kim; Jeom-Soo

    2008-04-15

    Lithium metal oxide compounds of nominal formula Li.sub.2MO.sub.2, in which M represents two or more positively charged metal ions, selected predominantly and preferably from the first row of transition metals are disclosed herein. The Li.sub.2MO.sub.2 compounds have a layered-type structure, which can be used as positive electrodes for lithium electrochemical cells, or as a precursor for the in-situ electrochemical fabrication of LiMO.sub.2 electrodes. The Li.sub.2MO.sub.2 compounds of the invention may have additional functions in lithium cells, for example, as end-of-discharge indicators, or as negative electrodes for lithium cells.

  3. Layered electrodes for lithium cells and batteries

    DOEpatents

    Johnson, Christopher S [Naperville, IL; Thackeray, Michael M [Naperville, IL; Vaughey, John T [Elmhurst, IL; Kahaian, Arthur J [Chicago, IL; Kim, Jeom-Soo [Naperville, IL

    2008-04-15

    Lithium metal oxide compounds of nominal formula Li.sub.2MO.sub.2, in which M represents two or more positively charged metal ions, selected predominantly and preferably from the first row of transition metals are disclosed herein. The Li.sub.2MO.sub.2 compounds have a layered-type structure, which can be used as positive electrodes for lithium electrochemical cells, or as a precursor for the in-situ electrochemical fabrication of LiMO.sub.2 electrodes. The Li.sub.2MO.sub.2 compounds of the invention may have additional functions in lithium cells, for example, as end-of-discharge indicators, or as negative electrodes for lithium cells.

  4. Electrochemical performance of platinum electrodes within the multi-electrode spiral nerve cuff.

    PubMed

    Rozman, Janez; Pečlin, Polona; Mehle, Andraž; Šala, Martin

    2014-09-01

    In this study, the electrochemical performance of platinum electrodes within a multi-electrode spiral cuff to be used for selective nerve stimulation was investigated. The original cuff, simplified into a half-cuff, contained a single row of nine electrodes (0.5 × 2 mm) at a distance of 2 mm from its inner surface. Cyclic voltammetry was used to investigate the electrochemical reactions at the electrode-electrolyte interface, to define a potential window within which the electrode could be safely used in selective nerve stimulation, to calculate the charge injection capacity and cathodal charge storage capacity. Voltage transients retrieved during excitation with quasitrapezoidal biphasic current pulses, tested by selective nerve stimulation of the isolated porcine left cervical vagus nerve segment, were used to determine the maximum polarization across the electrode-electrolyte interface and to calculate cathodic charge injection capacity of the electrode. The results show that the most negative and most positive potentials across the electrode-electrolyte interface reached -0.54 and 0.59 V; these did not exceed the safe potential limits for water electrolysis. Furthermore, the time integral of the cathodic current by cyclic voltammetry measured over the potential range of water electrolysis, actually representing the cathodal charge storage capacity, was approximately -4 mC cm(-2). The charge injection capacity, representing the maximum charge density injected in a current stimulation pulse, using only reversible processes, however, was around 75 µC cm(-2). In conclusion, both, the tested stimulation pulse and electrode are suitable for efficient and safe selective nerve stimulation.

  5. Improved capacitive EKG electrode

    NASA Technical Reports Server (NTRS)

    Day, J. L.; Griffith, M. E.; Portnox, W. M.; Stotts, L. J.

    1979-01-01

    Light, compact electrode monitors heart signals through burn ointment and requires no electrolyte paste for coupling to skin. Innovation is useful because of its ability to monitor heart condition of burn victims.

  6. Improved capacitive EKG electrode

    NASA Technical Reports Server (NTRS)

    Day, J. L.; Griffith, M. E.; Portnox, W. M.; Stotts, L. J.

    1979-01-01

    Light, compact electrode monitors heart signals through burn ointment and requires no electrolyte paste for coupling to skin. Innovation is useful because of its ability to monitor heart condition of burn victims.

  7. Giant-electrode welder

    NASA Technical Reports Server (NTRS)

    Atkins, B. R.; Chihoski, R. A.; Yashiro, F.

    1979-01-01

    Welder produces spot-welds in place of rivets and saves time and money. Unit comprised of concical copper electrode base diameter of 11.5 ft is also capable of welding very thin, hard aluminum alloys.

  8. Negative Certainty

    ERIC Educational Resources Information Center

    Ariso, José María

    2017-01-01

    The definitions of "negative knowledge" and the studies in this regard published to date have not considered the categorial distinction Wittgenstein established between knowledge and certainty. Hence, the important role that certainty, despite its omission, should have in these definitions and studies has not yet been shown. In this…

  9. Negative Certainty

    ERIC Educational Resources Information Center

    Ariso, José María

    2017-01-01

    The definitions of "negative knowledge" and the studies in this regard published to date have not considered the categorial distinction Wittgenstein established between knowledge and certainty. Hence, the important role that certainty, despite its omission, should have in these definitions and studies has not yet been shown. In this…

  10. Negative Numbers

    ERIC Educational Resources Information Center

    Galbraith, Mary J.

    1974-01-01

    Examination of models for representing integers demonstrates that formal operational thought is required for establishing the operations on integers. Advocated is the use of many models for introducing negative numbers but, apart from addition, it is recommended that operations on integers be delayed until the formal operations stage. (JP)

  11. Techniques of Electrode Fabrication

    NASA Astrophysics Data System (ADS)

    Guo, Liang; Li, Xinyong; Chen, Guohua

    Electrochemical applications using many kinds of electrode materials as an advanced oxidation/reduction technique have been a focus of research by a number of groups during the last two decades. The electrochemical approach has been adopted successfully to develop various environmental applications, mainly including water and wastewater treatment, aqueous system monitoring, and solid surface analysis. In this chapter, a number of methods for the fabrication of film-structured electrode materials were selectively reviewed. Firstly, the thermal decomposition method is briefly described, followed by introducing chemical vapor deposition (CVD) strategy. Especially, much attention was focused on introducing the methods to produce diamond novel film electrode owing to its unique physical and chemical properties. The principle and influence factors of hot filament CVD and plasma enhanced CVD preparation were interpreted by refereeing recent reports. Finally, recent developments that address electro-oxidation/reduction issues and novel electrodes such as nano-electrode and boron-doped diamond electrode (BDD) are presented in the overview.

  12. Conducting polymer electrodes for electroencephalography.

    PubMed

    Leleux, Pierre; Badier, Jean-Michel; Rivnay, Jonathan; Bénar, Christian; Hervé, Thierry; Chauvel, Patrick; Malliaras, George G

    2014-04-01

    Conducting polymer electrodes are developed on a flexible substrate for electroencephalography applications. These electrodes yield higher quality recordings than dry electrodes made from metal. Their performance is equivalent to commercial gel-assisted electrodes, paving the way for non-invasive, long-term monitoring of the human brain.

  13. Density impact on performance of composite Si/graphite electrodes

    SciTech Connect

    Dufek, Eric J.; Picker, Michael; Petkovic, Lucia M.

    2016-01-27

    The ability of alkali-substituted binders for composite Si and graphite negative electrodes to minimize capacity fade for lithium ion batteries is investigated. Polymer films and electrodes are described and characterized by FTIR following immersion in electrolyte (1:2 EC:DMC) for 24 h. FTIR analysis following electrode formation displayed similar alkali-ion dependent shifts in peak location suggesting that changes in the vibrational structure of the binder are maintained after electrode formation. The Si and graphite composite electrodes prepared using the alkali-substituted polyacrylates were also exposed to electrochemical cycling and it has been found that the performance of the Na-substituted binder is superior to a comparable density K-substituted system. However, in comparing performance across many different electrode densities attention needs to be placed on making comparisons at similar densities, as low density electrodes tend to exhibit lower capacity fade over cycling. This is highlighted by a 6% difference between a low density K-substituted electrode and a high density Na-substituted sample. As a result, this low variance between the two systems makes it difficult to quickly make a direct evaluation of binder performance unless electrode density is tightly controlled.

  14. Density impact on performance of composite Si/graphite electrodes

    DOE PAGES

    Dufek, Eric J.; Picker, Michael; Petkovic, Lucia M.

    2016-01-27

    The ability of alkali-substituted binders for composite Si and graphite negative electrodes to minimize capacity fade for lithium ion batteries is investigated. Polymer films and electrodes are described and characterized by FTIR following immersion in electrolyte (1:2 EC:DMC) for 24 h. FTIR analysis following electrode formation displayed similar alkali-ion dependent shifts in peak location suggesting that changes in the vibrational structure of the binder are maintained after electrode formation. The Si and graphite composite electrodes prepared using the alkali-substituted polyacrylates were also exposed to electrochemical cycling and it has been found that the performance of the Na-substituted binder is superiormore » to a comparable density K-substituted system. However, in comparing performance across many different electrode densities attention needs to be placed on making comparisons at similar densities, as low density electrodes tend to exhibit lower capacity fade over cycling. This is highlighted by a 6% difference between a low density K-substituted electrode and a high density Na-substituted sample. As a result, this low variance between the two systems makes it difficult to quickly make a direct evaluation of binder performance unless electrode density is tightly controlled.« less

  15. Capacitive de-ionization electrode

    DOEpatents

    Daily, III, William D.

    2013-03-19

    An electrode "cell" for use in a capacitive deionization (CDI) reactor consists of the electrode support structure, a non-reactive conductive material, the electrode accompaniment or substrate and a flow through screen/separator. These "layers" are repeated and the electrodes are sealed together with gaskets between two end plates to create stacked sets of alternating anode and cathode electrodes in the CDI reactor.

  16. Electrode screening by ionic liquids.

    PubMed

    Lynden-Bell, R M; Frolov, A I; Fedorov, M V

    2012-02-28

    In this work we are concerned with the short-range screening provided by the ionic liquid dimethylimidazolium chloride near a charged wall. We study the free energy profiles (or potentials of mean force) for charged and neutral solutes as a function of distance from a charged wall. Four different wall charge densities are used in addition to a wall with zero charge. The highest magnitude of the charge densities is ±1 e nm(-2) which is close to the maximum limit of charge densities accessible in experiments, while the intermediate charges ±0.5 e nm(-2) are in the range of densities typically used in most of the experimental studies. Positively and negatively charged solutes of approximately the size of a BF ion and a Cl(-) ion are used as probes. We find that the ionic liquid provides excellent electrostatic screening at a distance of 1-2 nm. The free energy profiles show minima which are due to layering in the ionic liquid near the electrodes. This indicates that the solute ions tend to displace ionic liquid ions in the layers when approaching the electrode. The important role of non-electrostatic forces is demonstrated by the oscillations in the free energy profiles of uncharged solutes as a function of distance from the wall.

  17. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions

    DOEpatents

    Mrazek, Franklin C.; Smaga, John A.; Battles, James E.

    1983-01-01

    A positive electrode for a secondary electrochemical cell wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

  18. NPPy With Dan DeVito

    NASA Image and Video Library

    The NPP mission mascot NPPy was found by the NPP Ground Project Manager Dan DeVito in a place called Svalbard, located 600 miles from the North Pole. Since then, Dan and other people on the NPP pro...

  19. Metal hydrides as negative electrode materials for Ni- MH batteries

    NASA Astrophysics Data System (ADS)

    Yartys, V.; Noreus, D.; Latroche, M.

    2016-01-01

    Structural, thermodynamical and electrochemical properties of metallic hydrides belonging to the pseudo-binary family A-Mg-Ni ( A: rare earths) are reviewed and compared. Technology aspects of bipolar cells are also discussed.

  20. Weld electrode cooling study

    NASA Astrophysics Data System (ADS)

    Masters, Robert C.; Simon, Daniel L.

    1999-03-01

    The U.S. auto/truck industry has been mandated by the Federal government to continuously improve their fleet average gas mileage, measured in miles per gallon. Several techniques are typically used to meet these mandates, one of which is to reduce the overall mass of cars and trucks. To help accomplish this goal, lighter weight sheet metal parts, with smaller weld flanges, have been designed and fabricated. This paper will examine the cooling characteristics of various water cooled weld electrodes and shanks used in resistance spot welding applications. The smaller weld flanges utilized in modern vehicle sheet metal fabrications have increased industry's interest in using one size of weld electrode (1/2 inch diameter) for certain spot welding operations. The welding community wants more data about the cooling characteristics of these 1/2 inch weld electrodes. To hep define the cooling characteristics, an infrared radiometer thermal vision system (TVS) was used to capture images (thermograms) of the heating and cooling cycles of several size combinations of weld electrodes under typical production conditions. Tests results will show why the open ended shanks are more suitable for cooling the weld electrode assembly then closed ended shanks.

  1. Nickel gradient electrode

    SciTech Connect

    Zimmerman, A.H.

    1988-03-31

    This invention relates generally to rechargeable batteries, and, in particular, relates to batteries that use nickel electrodes. It provides an improved nickel electrode with a selected gradient of additive materials. The concentration of additives in the impregnating solution are controlled during impregnation such that an additive gradient is generated. In the situation where the highest ionic conductivity is needed at the current collector boundary with the active material, the electrochemical impregnating solution is initially high in additive, and at the end of impregnation has been adjusted to significantly lower additive concentration. For chemical impregnation, the electrodes are similarly dipped in solutions that are initially high in additive. This invention is suitable for conventional additives such as cobalt, cadmium, barium, manganese, and zinc. It is therefore one objective of the invention to provide an improved nickel electrode of a battery cell with an additive in the active material to increase the life of the battery cell. Another objective is to provide for an improved nickel electrode having a greater concentration of additive near the current collector of nickel.

  2. Electronically conductive polymer binder for lithium-ion battery electrode

    DOEpatents

    Liu, Gao; Battaglia, Vincent S.; Park, Sang -Jae

    2015-10-06

    A family of carboxylic acid groups containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. Triethyleneoxide side chains provide improved adhesion to materials such as, graphite, silicon, silicon alloy, tin, tin alloy. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

  3. Electronically conductive polymer binder for lithium-ion battery electrode

    DOEpatents

    Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe; Wu, Mingyan

    2015-07-07

    A family of carboxylic acid groups containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. Triethyleneoxide side chains provide improved adhesion to materials such as, graphite, silicon, silicon alloy, tin, tin alloy. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

  4. Electronically conductive polymer binder for lithium-ion battery electrode

    DOEpatents

    Liu, Gao; Xun, Shidi; Battaglia, Vincent S.; Zheng, Honghe; Wu, Mingyan

    2017-08-01

    A family of carboxylic acid groups containing fluorene/fluorenon copolymers is disclosed as binders of silicon particles in the fabrication of negative electrodes for use with lithium ion batteries. Triethyleneoxide side chains provide improved adhesion to materials such as, graphite, silicon, silicon alloy, tin, tin alloy. These binders enable the use of silicon as an electrode material as they significantly improve the cycle-ability of silicon by preventing electrode degradation over time. In particular, these polymers, which become conductive on first charge, bind to the silicon particles of the electrode, are flexible so as to better accommodate the expansion and contraction of the electrode during charge/discharge, and being conductive promote the flow battery current.

  5. Multi-component intermetallic electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M; Trahey, Lynn; Vaughey, John T

    2015-03-10

    Multi-component intermetallic negative electrodes prepared by electrochemical deposition for non-aqueous lithium cells and batteries are disclosed. More specifically, the invention relates to composite intermetallic electrodes comprising two or more compounds containing metallic or metaloid elements, at least one element of which can react with lithium to form binary, ternary, quaternary or higher order compounds, these compounds being in combination with one or more other metals that are essentially inactive toward lithium and act predominantly, but not necessarily exclusively, to the electronic conductivity of, and as current collection agent for, the electrode. The invention relates more specifically to negative electrode materials that provide an operating potential between 0.05 and 2.0 V vs. metallic lithium.

  6. Positive-electrode current collector for liquid-metal cells

    DOEpatents

    Shimotake, H.; Bartholme, L.G.

    1982-09-27

    A current collector for the positive electrode of an electrochemical cell with a positive electrode including a sulfide. The cell also has a negative electrode and a molten salt electrolyte including halides of a metal selected from the alkali metals and the alkaline earth metals in contact with both the positive and negative electrodes. The current collector has a base metal of copper, silver, gold, aluminum or alloys thereof with a coating thereon of iron, nickel, chromium or alloys thereof. The current collector when subjected to cell voltage forms a sulfur-containing compound on the surface thereby substantially protecting the current collector from further attack by sulfur ions during cell operation. Both electroless and electrolytic processes may be used to deposit coatings.

  7. Positive electrode current collector for liquid metal cells

    DOEpatents

    Shimotake, Hiroshi; Bartholme, Louis G.

    1984-01-01

    A current collector for the positive electrode of an electrochemical cell with a positive electrode including a sulfide. The cell also has a negative electrode and a molten salt electrolyte including halides of a metal selected from the alkali metals and the alkaline earth metals in contact with both the positive and negative electrodes. The current collector has a base metal of copper, silver, gold, aluminum or alloys thereof with a coating thereon of iron, nickel, chromium or alloys thereof. The current collector when subjected to cell voltage forms a sulfur-containing compound on the surface thereby substantially protecting the current collector from further attack by sulfur ions during cell operation. Both electroless and electrolytic processes may be used to deposit coatings.

  8. Porous electrode preparation method

    DOEpatents

    Arons, R.M.; Dusek, J.T.

    1983-10-18

    A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity. 2 figs.

  9. Porous electrode preparation method

    DOEpatents

    Arons, Richard M.; Dusek, Joseph T.

    1983-01-01

    A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity.

  10. Fuel cell electrode

    SciTech Connect

    Struthers, R. C.

    1985-03-05

    A flat, laminated fuel cell gas electrode arranged between and separating gas and liquid mediums in a fuel cell. The electrode includes a flat, perforated sheet metal support and electric conductor part with a rear surface disposed toward the gas medium, a flat, hydrophobic gas permeable membrane with a rear surface in contact with a front surface of said part, a flat liquid and gas permeable metallic current collector with a rear surface spaced from a front surface of said membrane and with a front surface disposed toward the liquid medium, a catalytic barrier structure of bonded together particulate catalytic material and metal conductor filaments by and in electric conducting contact with the collector and having a rear surface in contact with the front surface of the membrane and a plurality of spaced apart electric conducting fasteners engaged with and between said part and collector securing the parts of the electrode in assembled relationship and electrically connecting the current collector with said part.

  11. Liquid-permeable electrode

    DOEpatents

    Folser, George R.

    1980-01-01

    Electrodes for use in an electrolytic cell, which are liquid-permeable and have low electrical resistance and high internal surface area are provided of a rigid, porous, carbonaceous matrix having activated carbon uniformly embedded throughout. The activated carbon may be catalyzed with platinum for improved electron transfer between electrode and electrolyte. Activated carbon is mixed with a powdered thermosetting phenolic resin and compacted to the desired shape in a heated mold to melt the resin and form the green electrode. The compact is then heated to a pyrolyzing temperature to carbonize and volatilize the resin, forming a rigid, porous structure. The permeable structure and high internal surface area are useful in electrolytic cells where it is necessary to continuously remove the products of the electrochemical reaction.

  12. Composite carbon foam electrode

    DOEpatents

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1997-05-06

    Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  13. Composite carbon foam electrode

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    1997-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

  14. MHD generator electrode development

    NASA Astrophysics Data System (ADS)

    Retallick, F. D.; Dietrick, D. L.; Lloyd, I.; Rossing, B. R.; Smith, R.

    1981-08-01

    Metallurgical and engineering understanding of cold metallic electrode alternatives to the continued use of platinum as an anode clad material is discussed. The results of evaluating materials for MHD electrodes through use of a laboratory electrochemical and arc test are presented. Results for standard available materials as well as for some specially fabricated ones are presented. The development of a high temperature (11000 C to 14000 C) electrochemical test is outlined. Initial operation of the Westinghouse Electrode Systems Test Facility (WESTF), since major modification to include a magnet, is reported for a test section designed to operate as a small scale MHD generator and for test sections designed for the purpose of materials test evaluation in the operating MHD plasma environment.

  15. Lateralization of cortical negative motor areas.

    PubMed

    Borggraefe, Ingo; Catarino, Claudia B; Rémi, Jan; Vollmar, Christian; Peraud, Aurelia; Winkler, Peter A; Noachtar, Soheyl

    2016-10-01

    The lateral and mesial aspects of the central and frontal cortex were studied by direct electrical stimulation of the cortex in epilepsy surgery candidates in order to determine the localization of unilateral and bilateral negative motor responses. Results of electrical cortical stimulation were examined in epilepsy surgery candidates in whom invasive electrodes were implanted. The exact localization of subdural electrodes was defined by fusion of 3-dimensional reconstructed MRI and CT images in 13 patients and by analysis of plane skull X-rays and intraoperative visual localization of the electrodes in another 7 patients. Results of electrical stimulation of the cortex were evaluated in a total of 128 patients in whom invasive electrodes were implanted for planning resective epilepsy surgery. Twenty patients, in whom negative motor responses were obtained, were included in the study. Bilateral upper limb negative motor responses were more often elicited from stimulation of the mesial frontal cortex whereas stimulation of the lateral central cortex leads to contralateral upper limb negative motor responses (p<0.0001). Bilateral negative motor responses were exclusively found in the superior frontal gyrus whereas contralateral negative motor responses localized predominantly in the anterior part of the precentral gyrus (p<0.0001). Exact localization using 3-D fusion methods revealed that negative motor areas are widely distributed throughout the precentral gyrus and the mesial fronto-central cortex showing functional differences with regard to unilateral and bilateral upper limb representation. The lateral fronto-central negative motor area serves predominantly contralateral upper limb motor control whereas the mesial frontal negative motor area represents bilateral upper limb movement control. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  16. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.

    1979-01-01

    A ceramic component suitable for preparing MHD generator electrodes consists of HfO.sub.2 and sufficient Tb.sub.4 O.sub.7 to stabilize at least 60 volume percent of the HfO.sub.2 into the cubic structure. The ceramic component may also contain a small amount of PrO.sub.2, Yb.sub.2 O.sub.3 or a mixture of both to improve stability and electronic conductivity of the electrode. The component is highly resistant to corrosion by molten potassium seed and molten coal slag in the MHD fluid and exhibits both ionic and electronic conductivity.

  17. Sandwich-type electrode

    DOEpatents

    Lu, Wen-Tong P.; Garcia, Earl R.

    1983-01-01

    Disclosed is an improvement on a method of making an electrode wherein a suspension in a liquid is prepared of a powdered catalyst containing a noble metal, carbon powder and a binder, and the suspension is poured over a carbon substrate dried, compressed and sintered to form a solid catalyst layer bonded to the carbon substrate. The improvement is placing a carbon paper on the catalyst layer prior to compressing. The improved electrode can be used as either a cathode or an anode in a sulfur dioxide depolarized electrolyzer in a process for producing hydrogen from water.

  18. Aluminum reference electrode

    DOEpatents

    Sadoway, D.R.

    1988-08-16

    A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.

  19. Aluminum reference electrode

    DOEpatents

    Sadoway, Donald R.

    1988-01-01

    A stable reference electrode for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na.sub.3 AlF.sub.6, wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution.

  20. Electrical properties of textile electrodes.

    PubMed

    Rattfalt, Linda; Chedid, Michel; Hult, Peter; Lindén, Maria; Ask, Per

    2007-01-01

    In this study we aim to explain the behavior of textile electrodes due to their construction techniques. Three textile electrodes were tested for electrode impedance and polarization potentials. The multifilament yarn (A) is favorable for its low thread resistance. Although, when knitted into electrodes, the staple fiber yarn (B) showed a comparable and satisfiable electrode impedance. The multifilament yarn had however a lower polarization potential drift then the other specimens. The monofilament yarn (C) had high electrode impedance and varying mean polarization potentials due to its conductive material and small contact area with the skin.

  1. Dual porosity gas evolving electrode

    DOEpatents

    Townsend, Carl W.

    1994-01-01

    A dual porosity electrode for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

  2. Dual porosity gas evolving electrode

    DOEpatents

    Townsend, C.W.

    1994-11-15

    A dual porosity electrode is described for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

  3. Oligonucleotide probes functionalization of nanogap electrodes.

    PubMed

    Zaffino, Rosa Letizia; Mir, Mònica; Samitier, Josep

    2017-05-15

    Nanogap electrodes have attracted a lot of consideration as promising platform for molecular electronic and biomolecules detection. This is mainly for their higher aspect ratio, and because their electrical properties are easily accessed by current-voltage measurements. Nevertheless, application of standard current-voltages measurements used to characterize nanogap response, and/or to modify specific nanogap electrodes properties, represents an issue. Since the strength of electrical fields in nanoscaled devices can reach high values, even at low voltages. Here, we analyzed the effects induced by different methods of surface modification of nanogap electrodes, in test-voltage application, employed for the electrical detection of a desoxyribonucleic acid (DNA) target. Nanogap electrodes were functionalized with two antisymmetric oligo-probes designed to have 20 terminal bases complementary to the edges of the target, which after hybridization bridges the nanogap, closing the electrical circuit. Two methods of functionalization were studied for this purpose; a random self-assembling of a mixture of the two oligo-probes (OPs) used in the platform, and a selective method that controls the position of each OP at selected side of nanogap electrodes. We used for this aim, the electrophoretic effect induced on negatively charged probes by the application of an external direct current voltage. The results obtained with both functionalization methods where characterized and compared in terms of electrode surface covering, calculated by using voltammetry analysis. Moreover, we contrasted the electrical detection of a DNA target in the nanogap platform either in site-selective and in randomly assembled nanogap. According to our results, a denser, although not selective surface functionalization, is advantageous for such kind of applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Virtual electrodes for high-density electrode arrays

    DOEpatents

    Cela, Carlos J.; Lazzi, Gianluca

    2015-10-13

    The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.

  5. Electrode Migration in Patients with Perimodiolar Cochlear Implant Electrodes.

    PubMed

    Mittmann, Philipp; Rademacher, Grit; Mutze, Sven; Ernst, Arneborg; Todt, Ingo

    2015-01-01

    Migration of a cochlear implant electrode is a hitherto uncommon complication. So far, array migration has only been observed in lateral wall electrodes. Between 1999 and 2014, a total of 27 patients received bilateral perimodiolar electrode arrays at our institution. The insertion depth angle was estimated on the initial postoperative scans and compared with the insertion depth angle of the postoperative scans performed after contralateral cochlear implantation. Seven (25.93%) patients were found to have an electrode array migration of more than 15°. Electrode migration in perimodiolar electrodes seems to be less frequent and to occur to a lower extent than in lateral wall electrodes. Electrode migration was clinically asymptomatic in all cases. © 2015 S. Karger AG, Basel.

  6. Virtual electrodes for high-density electrode arrays

    DOEpatents

    Cela, Carlos Jose; Lazzi, Gianluca

    2017-05-23

    The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.

  7. Flexible electrode belt for EIT using nanofiber web dry electrodes.

    PubMed

    Oh, Tong In; Kim, Tae Eui; Yoon, Sun; Kim, Kap Jin; Woo, Eung Je; Sadleir, Rosalind J

    2012-10-01

    Efficient connection of multiple electrodes to the body for impedance measurement and voltage monitoring applications is of critical importance to measurement quality and practicality. Electrical impedance tomography (EIT) experiments have generally required a cumbersome procedure to attach the multiple electrodes needed in EIT. Once placed, these electrodes must then maintain good contact with the skin during measurements that may last several hours. There is usually also the need to manage the wires that run between the electrodes and the EIT system. These problems become more severe as the number of electrodes increases, and may limit the practicality and portability of this imaging method. There have been several trials describing human-electrode interfaces using configurations such as electrode belts, helmets or rings. In this paper, we describe an electrode belt we developed for long-term EIT monitoring of human lung ventilation. The belt included 16 embossed electrodes that were designed to make good contact with the skin. The electrodes were fabricated using an Ag-plated PVDF nanofiber web and metallic threads. A large contact area and padding were used behind each electrode to improve subject comfort and reduce contact impedances. The electrodes were incorporated, equally spaced, into an elasticated fabric belt. We tested the electrode belt in conjunction with the KHU Mark1 multi-frequency EIT system, and demonstrate time-difference images of phantoms and human subjects during normal breathing and running. We found that the Ag-plated PVDF nanofiber web electrodes were suitable for long-term measurement because of their flexibility and durability. Moreover, the contact impedance and stability of the Ag-plated PVDF nanofiber web electrodes were found to be comparable to similarly tested Ag/AgCl electrodes.

  8. Development of electrodes for the NASA iron/chromium

    NASA Astrophysics Data System (ADS)

    Swette, L.; Jalan, V.

    1984-06-01

    This program was directed primarily to the development of the negative (Cr3+/Cr2+) electrode for the NASA chromous/ferric Redox battery. The investigation of the effects of substrate processing and gold/lead catalyzation parameters on electrochemical performance were continued. In addition, the effects of reactant cross-mixing, acidity level, and temperature were examined for both Redox couples. Finally, the performance of optimized electrodes was tested in system hardware (1/3 square foot single cell). The major findings are discussed: (1) The recommended processing temperature for the carbon felt, as a substrate for the negative electrode, is 1650 to 1750 C, (2) The recommended gold catalyzation procedure is essentially the published NASA procedure (NASA TM-82724, Nov. 1981) based on deposition from aqueous methanol solution, with the imposition of a few controls such as temperature (25 C) and precatalyzation pH of the felt (7), (3) Experimental observations of the gold catalyzation process and subsequent electron microscopy indicate that the gold is deposited from the colloidal state, induced by contact of the solution with the carbon felt, (4) Electrodeposited lead appears to be present as a thin uniform layer over the entire surface of the carbon fibers, rather than an discrete particles, and (5) Cross-mixing of reactants (Fe-2+ in negative electrode solution or Cr-3+ in the positive electrode solution) did not appear to produce significant interference at either electrode.

  9. Development of electrodes for the NASA iron/chromium

    NASA Technical Reports Server (NTRS)

    Swette, L.; Jalan, V.

    1984-01-01

    This program was directed primarily to the development of the negative (Cr3+/Cr2+) electrode for the NASA chromous/ferric Redox battery. The investigation of the effects of substrate processing and gold/lead catalyzation parameters on electrochemical performance were continued. In addition, the effects of reactant cross-mixing, acidity level, and temperature were examined for both Redox couples. Finally, the performance of optimized electrodes was tested in system hardware (1/3 square foot single cell). The major findings are discussed: (1) The recommended processing temperature for the carbon felt, as a substrate for the negative electrode, is 1650 to 1750 C, (2) The recommended gold catalyzation procedure is essentially the published NASA procedure (NASA TM-82724, Nov. 1981) based on deposition from aqueous methanol solution, with the imposition of a few controls such as temperature (25 C) and precatalyzation pH of the felt (7), (3) Experimental observations of the gold catalyzation process and subsequent electron microscopy indicate that the gold is deposited from the colloidal state, induced by contact of the solution with the carbon felt, (4) Electrodeposited lead appears to be present as a thin uniform layer over the entire surface of the carbon fibers, rather than an discrete particles, and (5) Cross-mixing of reactants (Fe-2+ in negative electrode solution or Cr-3+ in the positive electrode solution) did not appear to produce significant interference at either electrode.

  10. 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.

  11. The standardized EEG electrode array of the IFCN.

    PubMed

    Seeck, Margitta; Koessler, Laurent; Bast, Thomas; Leijten, Frans; Michel, Christoph; Baumgartner, Christoph; He, Bin; Beniczky, Sándor

    2017-10-01

    Standardized EEG electrode positions are essential for both clinical applications and research. The aim of this guideline is to update and expand the unifying nomenclature and standardized positioning for EEG scalp electrodes. Electrode positions were based on 20% and 10% of standardized measurements from anatomical landmarks on the skull. However, standard recordings do not cover the anterior and basal temporal lobes, which is the most frequent source of epileptogenic activity. Here, we propose a basic array of 25 electrodes including the inferior temporal chain, which should be used for all standard clinical recordings. The nomenclature in the basic array is consistent with the 10-10-system. High-density scalp EEG arrays (64-256 electrodes) allow source imaging with even sub-lobar precision. This supplementary exam should be requested whenever necessary, e.g. search for epileptogenic activity in negative standard EEG or for presurgical evaluation. In the near future, nomenclature for high density electrodes arrays beyond the 10-10 system needs to be defined, to allow comparison and standardized recordings across centers. Contrary to the established belief that smaller heads needs less electrodes, in young children at least as many electrodes as in adults should be applied due to smaller skull thickness and the risk of spatial aliasing. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  12. Flower-like Palladium Nanoclusters Decorated Graphene Electrodes for Ultrasensitive and Flexible Hydrogen Gas Sensing

    NASA Astrophysics Data System (ADS)

    Shin, Dong Hoon; Lee, Jun Seop; Jun, Jaemoon; An, Ji Hyun; Kim, Sung Gun; Cho, Kyung Hee; Jang, Jyongsik

    2015-07-01

    Flower-like palladium nanoclusters (FPNCs) are electrodeposited onto graphene electrode that are prepared by chemical vapor deposition (CVD). The CVD graphene layer is transferred onto a poly(ethylene naphthalate) (PEN) film to provide a mechanical stability and flexibility. The surface of the CVD graphene is functionalized with diaminonaphthalene (DAN) to form flower shapes. Palladium nanoparticles act as templates to mediate the formation of FPNCs, which increase in size with reaction time. The population of FPNCs can be controlled by adjusting the DAN concentration as functionalization solution. These FPNCs_CG electrodes are sensitive to hydrogen gas at room temperature. The sensitivity and response time as a function of the FPNCs population are investigated, resulted in improved performance with increasing population. Furthermore, the minimum detectable level (MDL) of hydrogen is 0.1 ppm, which is at least 2 orders of magnitude lower than that of chemical sensors based on other Pd-based hybrid materials.

  13. Battery electrode growth accommodation

    DOEpatents

    Bowen, Gerald K.; Andrew, Michael G.; Eskra, Michael D.

    1992-01-01

    An electrode for a lead acid flow through battery, the grids including a plastic frame, a plate suspended from the top of the frame to hang freely in the plastic frame and a paste applied to the plate, the paste being free to allow for expansion in the planar direction of the grid.

  14. Photoelectrosynthesis at semiconductor electrodes

    SciTech Connect

    Nozik, A. J.

    1980-12-01

    The general principles of photoelectrochemistry and photoelectrosynthesis are reviewed and some new developments in photoelectrosynthesis are discussed. Topics include energetics of semiconductor-electrolyte interfaces(band-edge unpinning); hot carrier injection at illuminated semiconductor-electrolyte junctions; derivatized semiconductor electrodes; particulate photoelectrochemical systems; layered compounds and other new materials; and dye sensitization. (WHK)

  15. Capacitive electrodes in electroencephalography.

    PubMed

    von Ellenrieder, Nicolás; Spinelli, Enrique; Muravchik, Carlos H

    2006-01-01

    We present a forward problem formulation for computing biopotentials measured with dry or capacitive electrodes. This formulation is not quasistatic and has mixed boundary conditions. Our results show that simple approximations to the measurements based on capacitive coupling are adequate in most situations. We study the range of validity and errors committed in the EEG forward and inverse problems when using this approximation.

  16. Dry EEG Electrodes

    PubMed Central

    Lopez-Gordo, M. A.; Sanchez-Morillo, D.; Valle, F. Pelayo

    2014-01-01

    Electroencephalography (EEG) emerged in the second decade of the 20th century as a technique for recording the neurophysiological response. Since then, there has been little variation in the physical principles that sustain the signal acquisition probes, otherwise called electrodes. Currently, new advances in technology have brought new unexpected fields of applications apart from the clinical, for which new aspects such as usability and gel-free operation are first order priorities. Thanks to new advances in materials and integrated electronic systems technologies, a new generation of dry electrodes has been developed to fulfill the need. In this manuscript, we review current approaches to develop dry EEG electrodes for clinical and other applications, including information about measurement methods and evaluation reports. We conclude that, although a broad and non-homogeneous diversity of approaches has been evaluated without a consensus in procedures and methodology, their performances are not far from those obtained with wet electrodes, which are considered the gold standard, thus enabling the former to be a useful tool in a variety of novel applications. PMID:25046013

  17. Enhanced surface production in H- ion sources by introducing a negatively biased secondary electrodea)

    NASA Astrophysics Data System (ADS)

    An, YoungHwa; Jung, BongKi; Hwang, Y. S.

    2010-02-01

    A transformer coupled plasma negative hydrogen ion source with an external rf antenna has been developed at SNU, which is capable of continuous operation with long lifetime. A positively biased plasma electrode (PE) has been successfully used for the optimization of H- extraction. With molybdenum-coated stainless steel PE, the enhancement of H- production at the electrode surface was observed at the bias voltage lower than the plasma potential. However, the low bias voltage is unfavorable to H- beam extraction since the negative ions are repelled. A second electrode is inserted in front of the PE to enhance H- production at the electrode surface without impeding beam extraction. By biasing the secondary electrode (SE) more negatively, H- production is clearly enhanced although the SE itself reduces H- beam currents because of suppressed electron transport in front of the PE. In this configuration enhancement of surface productions is most pronounced in tantalum electrode among various electrode materials.

  18. Robust Molecular Anchoring to Graphene Electrodes.

    PubMed

    Sadeghi, Hatef; Sangtarash, Sara; Lambert, Colin

    2017-08-09

    Recent advances in the engineering of picoscale gaps between electroburnt graphene electrodes provide new opportunities for studying electron transport through electrostatically gated single molecules. But first we need to understand and develop strategies for anchoring single molecules to such electrodes. Here, for the first time we present a systematic theoretical study of transport properties using four different modes of anchoring zinc-porphyrin monomer, dimer, and trimer molecular wires to graphene electrodes. These involve either amine anchor groups, covalent C-C bonds to the edges of the graphene, or coupling via π-π stacking of planar polyaromatic hydrocarbons formed from pyrene or tetrabenzofluorene (TBF). π-π stacked pyrene anchors are particularly stable, which may be advantageous for forming robust single-molecule transistors. Despite their planar, multiatom coupling to the electrodes, pyrene anchors can exhibit both destructive interference and different degrees of constructive interference, depending on their connectivity to the porphyrin wire, which makes them attractive also for thermoelectricity. TBF anchors are more weakly coupled to both the graphene and the porphyrin wires and induce negative differential conductance at finite source-drain voltages. Furthermore, although direct C-C covalent bonding to the edges of graphene electrodes yields the highest electrical conductance, electron transport is significantly affected by the shape and size of the graphene electrodes because the local density of states at the carbon atoms connecting the electrode edges to the molecule is sensitive to the electrode surface shape. This sensitivity suggests that direct C-C bonding may be the most desirable for sensing applications. The ordering of the low-bias electrical conductances with different anchors is as follows: direct C-C coupling > π-π stacking with the pyrene anchors > direct coupling via amine anchors > π-π stacking with TBF anchors. Despite

  19. Zinc electrode in alkaline electrolyte

    SciTech Connect

    McBreen, J.

    1995-12-31

    The zinc electrode in alkaline electrolyte is unusual in that supersaturated zincate solutions can form during discharge and spongy or mossy zinc deposits can form on charge at low overvoltages. The effect of additives on regular pasted ZnO electrodes and calcium zincate electrodes is discussed. The paper also reports on in situ x-ray absorption (XAS) results on mossy zinc deposits.

  20. Corner Office: Google's Dan Clancy

    ERIC Educational Resources Information Center

    Albanese, Andrew Richard; Oder, Norman

    2009-01-01

    This article presents an interview with Dan Clancy, engineering director for Google Book Search. In this interview, Clancy talks about the pending Google Book Search settlement, involving millions of volumes digitized from libraries, which drew a lawsuit from the Association of American Publishers and the Authors Guild. He also discusses pricing,…

  1. Corner Office: Google's Dan Clancy

    ERIC Educational Resources Information Center

    Albanese, Andrew Richard; Oder, Norman

    2009-01-01

    This article presents an interview with Dan Clancy, engineering director for Google Book Search. In this interview, Clancy talks about the pending Google Book Search settlement, involving millions of volumes digitized from libraries, which drew a lawsuit from the Association of American Publishers and the Authors Guild. He also discusses pricing,…

  2. Electroformed Electrodes for Electrical-Discharge Machining

    NASA Technical Reports Server (NTRS)

    Werner, A.; Cassidenti, M.

    1984-01-01

    Copper electrodes replace graphite electrodes in many instances of electrical-discharge machining (EDM) of complex shapes. Copper electrodes wear longer and cause less contamination of EDM dielectric fluid than do graphite electrodes.

  3. Hydrogenase electrodes for fuel cells.

    PubMed

    Karyakin, A A; Morozov, S V; Karyakina, E E; Zorin, N A; Perelygin, V V; Cosnier, S

    2005-02-01

    Considering crucial problems that limit use of platinum-based fuel cells, i.e. cost and availability, poisoning by fuel impurities and low selectivity, we propose electrocatalysis by enzymes as a valuable alternative to noble metals. Hydrogenase electrodes in neutral media achieve hydrogen equilibrium potential (providing 100% energy conversion), and display high activity in H(2) electrooxidation, which is similar to that of Pt-based electrodes in sulphuric acid. In contrast with platinum, enzyme electrodes are highly selective for their substrates, and are not poisoned by fuel impurities. Hydrogenase electrodes are capable of consuming hydrogen directly from microbial media, which ensures their use as fuel electrodes in treatment of organic wastes.

  4. Catalyzed enzyme electrodes

    DOEpatents

    Zawodzinski, Thomas A.; Wilson, Mahlon S.; Rishpon, Judith; Gottesfeld, Shimshon

    1993-01-01

    An enzyme electrode is prepared with a composite coating on an electrical conductor. The composite coating is formed from a casting solution of a perfluorosulfonic acid polymer, an enzyme, and a carbon supported catalyst. The solution may be cast directly on the conductor surface or may be formed as a membrane and applied to the surface. The perfluorosulfonic acid ionomer formed from the casting solution provides an insoluble biocompatible protective matrix for the enzyme and acts to retain the enzyme for long term availability in the electrode structure. The carbon supported catalyst provides catalytic sites throughout the layer for the oxidation of hydrogen peroxide from the enzyme reactions. The carbon support then provides a conductive path for establishing an electrical signal to the electrical conductor. In one embodiment, the electrical conductor is a carbon cloth that permits oxygen or other gas to be introduced to the perfluorosulfonic polymer to promote the enzyme reaction independent of oxygen in the solution being tested.

  5. Inert electrode connection

    SciTech Connect

    Weyand, John D.; Woods, Robert W.; DeYoung, David H.; Ray, Siba P.

    1985-01-01

    An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000-20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1200.degree.-1500.degree. C.

  6. Inert electrode connection

    DOEpatents

    Weyand, J.D.; Woods, R.W.; DeYoung, D.H.; Ray, S.P.

    1985-02-19

    An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000--20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1,200--1,500 C. 5 figs.

  7. Magnetohydrodynamic generator electrode

    DOEpatents

    Marchant, David D.; Killpatrick, Don H.; Herman, Harold; Kuczen, Kenneth D.

    1979-01-01

    An improved electrode for use as a current collector in the channel of a magnetohydrodynamid (MHD) generator utilizes an elongated monolithic cap of dense refractory material compliantly mounted to the MHD channel frame for collecting the current. The cap has a central longitudinal channel which contains a first layer of porous refractory ceramic as a high-temperature current leadout from the cap and a second layer of resilient wire mesh in contact with the first layer as a low-temperature current leadout between the first layer and the frame. Also described is a monolithic ceramic insulator compliantly mounted to the frame parallel to the electrode by a plurality of flexible metal strips.

  8. Long life reference electrode

    DOEpatents

    Yonco, Robert M.; Nagy, Zoltan

    1989-01-01

    An external, reference electrode is provided for long term use with a high temperature, high pressure system. The electrode is arranged in a vertical, electrically insulative tube with an upper portion serving as an electrolyte reservior and a lower portion in electrolytic communication with the system to be monitored. The lower end portion includes a flow restriction such as a porous plug to limit the electrolyte release into the system. A piston equalized to the system pressure is fitted into the upper portion of the tube to impart a small incremental pressure to the electrolyte. The piston is selected of suitable size and weight to cause only a slight flow of electrolyte through the porous plug into the high pressure system. This prevents contamination of the electrolyte but is of such small flow rate that operating intervals of a month or more can be achieved.

  9. Long life reference electrode

    DOEpatents

    Yonco, R.M.; Nagy, Z.

    1987-07-30

    An external, reference electrode is provided for long term use with a high temperature, high pressure system. The electrode is arranged in a vertical, electrically insulative tube with an upper portion serving as an electrolyte reservoir and a lower portion in electrolytic communication with the system to be monitored. The lower end portion includes a flow restriction such as a porous plug to limit the electrolyte release into the system. A piston equalized to the system pressure is fitted into the upper portion of the tube to impart a small incremental pressure to the electrolyte. The piston is selected of suitable size and weight to cause only a slight flow of electrolyte through the porous plug into the high pressure system. This prevents contamination of the electrolyte but is of such small flow rate that operating intervals of a month or more can be achieved. 2 figs.

  10. Long life reference electrode

    DOEpatents

    Yonco, R.M.; Nagy, Z.

    1989-04-04

    An external, reference electrode is provided for long term use with a high temperature, high pressure system. The electrode is arranged in a vertical, electrically insulative tube with an upper portion serving as an electrolyte reservoir and a lower portion in electrolytic communication with the system to be monitored. The lower end portion includes a flow restriction such as a porous plug to limit the electrolyte release into the system. A piston equalized to the system pressure is fitted into the upper portion of the tube to impart a small incremental pressure to the electrolyte. The piston is selected of suitable size and weight to cause only a slight flow of electrolyte through the porous plug into the high pressure system. This prevents contamination of the electrolyte but is of such small flow rate that operating intervals of a month or more can be achieved. 2 figs.

  11. Ice electrode electrolytic cell

    DOEpatents

    Glenn, David F.; Suciu, Dan F.; Harris, Taryl L.; Ingram, Jani C.

    1993-01-01

    This invention relates to a method and apparatus for removing heavy metals from waste water, soils, or process streams by electrolytic cell means. The method includes cooling a cell cathode to form an ice layer over the cathode and then applying an electric current to deposit a layer of the heavy metal over the ice. The metal is then easily removed after melting the ice. In a second embodiment, the same ice-covered electrode can be employed to form powdered metals.

  12. Nickel anode electrode

    DOEpatents

    Singh, Prabhakar; Benedict, Mark

    1987-01-01

    A nickel anode electrode fabricated by oxidizing a nickel alloying material to produce a material whose exterior contains nickel oxide and whose interior contains nickel metal throughout which is dispersed the oxide of the alloying material and by reducing and sintering the oxidized material to form a product having a nickel metal exterior and an interior containing nickel metal throughout which is dispersed the oxide of the alloying material.

  13. Fuel cell oxygen electrode

    DOEpatents

    Shanks, H.R.; Bevolo, A.J.; Danielson, G.C.; Weber, M.F.

    An oxygen electrode for a fuel cell utilizing an acid electrolyte has a substrate of an alkali metal tungsten bronze of the formula: A/sub x/WO/sub 3/ where A is an alkali metal and x is at least 0.2, which is covered with a thin layer of platinum tungsten bronze of the formula: Pt/sub y/WO/sub 3/ where y is at least 0.8.

  14. Fuel cell oxygen electrode

    DOEpatents

    Shanks, Howard R.; Bevolo, Albert J.; Danielson, Gordon C.; Weber, Michael F.

    1980-11-04

    An oxygen electrode for a fuel cell utilizing an acid electrolyte has a substrate of an alkali metal tungsten bronze of the formula: A.sub.x WO.sub.3 where A is an alkali metal and x is at least 0.2, which is covered with a thin layer of platinum tungsten bronze of the formula: Pt.sub.y WO.sub.3 where y is at least 0.8.

  15. Ice electrode electrolytic cell

    DOEpatents

    Glenn, D.F.; Suciu, D.F.; Harris, T.L.; Ingram, J.C.

    1993-04-06

    This invention relates to a method and apparatus for removing heavy metals from waste water, soils, or process streams by electrolytic cell means. The method includes cooling a cell cathode to form an ice layer over the cathode and then applying an electric current to deposit a layer of the heavy metal over the ice. The metal is then easily removed after melting the ice. In a second embodiment, the same ice-covered electrode can be employed to form powdered metals.

  16. Electrostatic Levitator Electrode Layout

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Schematic of Electrostatic Levitator (ESL) electrodes and controls system. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  17. Membrane reference electrode

    DOEpatents

    Redey, L.; Bloom, I.D.

    1988-01-21

    A reference electrode utilizes a small thin, flat membrane of a highly conductive glass placed on a small diameter insulator tube having a reference material inside in contact with an internal voltage lead. When the sensor is placed in a non-aqueous ionic electrolytic solution, the concentration difference across the glass membrane generates a low voltage signal in precise relationship to the concentration of the species to be measured, with high spatial resolution. 2 figs.

  18. Membrane reference electrode

    DOEpatents

    Redey, Laszlo; Bloom, Ira D.

    1989-01-01

    A reference electrode utilizes a small thin, flat membrane of a highly conductive glass placed on a small diameter insulator tube having a reference material inside in contact with an internal voltage lead. When the sensor is placed in a non-aqueous ionic electrolytic solution, the concentration difference across the glass membrane generates a low voltage signal in precise relationship to the concentration of the species to be measured with high spatial resolution.

  19. Electrocatalysts for oxygen electrodes

    SciTech Connect

    Yeager, E.B. )

    1991-10-01

    The objectives of the research were: to develop further understanding of the factors controlling O{sub 2} reduction and generation on various electrocatalysts, including transition metal macrocycles and oxides: to use this understanding to identify and develop much higher activity catalysts, both monofunction and bifunction; and to establish how catalytic activity for a given O{sub 2} electrocatalyst depends on catalyst-support interactions and to identify stable catalyst supports for bifunctional electrodes.

  20. Ice electrode electrolytic cell

    SciTech Connect

    Glenn, D.F.; Suciu, D.F.; Harris, T.L.; Ingram, J.C.

    1992-12-31

    This invention relates to a method and apparatus for removing heavy metals from waste water, soils, or process streams by electrolytic cell means. The method includes cooling a cell cathode to form an ice layer over the cathode and then applying an electric current to deposit a layer of the heavy metal over the ice. The metal is then easily removed after melting the ice. In a second embodiment, the same ice-covered electrode can be employed to form powdered metals.

  1. Electrostatic Levitator Electrode Layout

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Schematic of Electrostatic Levitator (ESL) electrodes and controls system. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  2. Transparent electrode for optical switch

    DOEpatents

    Goldhar, Julius; Henesian, Mark A.

    1986-01-01

    A low pressure gas electrode utilizing ionized gas in a glow discharge regime forms a transparent electrode for electro-optical switches. The transparent electrode comprises a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the electrode is a transparent electrode. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. The plasma can be created either by the main high voltage pulser used to charge up the crystal or by auxiliary discharges or external sources of ionization. A typical configuration utilizes 10 torr argon in the discharge region adjacent to each crystal face.

  3. Electrode array for neural stimulation

    DOEpatents

    Wessendorf, Kurt O.; Okandan, Murat; Stein, David J.; Yang, Pin; Cesarano, III, Joseph; Dellinger, Jennifer

    2011-08-16

    An electrode array for neural stimulation is disclosed which has particular applications for use in a retinal prosthesis. The electrode array can be formed as a hermetically-sealed two-part ceramic package which includes an electronic circuit such as a demultiplexer circuit encapsulated therein. A relatively large number (up to 1000 or more) of individually-addressable electrodes are provided on a curved surface of a ceramic base portion the electrode array, while a much smaller number of electrical connections are provided on a ceramic lid of the electrode array. The base and lid can be attached using a metal-to-metal seal formed by laser brazing. Electrical connections to the electrode array can be provided by a flexible ribbon cable which can also be used to secure the electrode array in place.

  4. Exploring electrolyte organization in supercapacitor electrodes with solid-state NMR

    NASA Astrophysics Data System (ADS)

    Deschamps, Michaël; Gilbert, Edouard; Azais, Philippe; Raymundo-Piñero, Encarnación; Ammar, Mohammed Ramzi; Simon, Patrick; Massiot, Dominique; Béguin, François

    2013-04-01

    Supercapacitors are electrochemical energy-storage devices that exploit the electrostatic interaction between high-surface-area nanoporous electrodes and electrolyte ions. Insight into the molecular mechanisms at work inside supercapacitor carbon electrodes is obtained with 13C and 11B ex situ magic-angle spinning nuclear magnetic resonance (MAS-NMR). In activated carbons soaked with an electrolyte solution, two distinct adsorption sites are detected by NMR, both undergoing chemical exchange with the free electrolyte molecules. On charging, anions are substituted by cations in the negative carbon electrode and cations by anions in the positive electrode, and their proportions in each electrode are quantified by NMR. Moreover, acetonitrile molecules are expelled from the adsorption sites at the negative electrode alone. Two nanoporous carbon materials were tested, with different nanotexture orders (using Raman and 13C MAS-NMR spectroscopies), and the more disordered carbon shows a better capacitance and a better tolerance to high voltages.

  5. Carbon cloth supported electrode

    DOEpatents

    Lu, Wen-Tong P.; Ammon, Robert L.

    1982-01-01

    A flow-by anode is disclosed made by preparing a liquid suspension of about to about 18% by weight solids, the solids comprising about 3.5 to about 8% of a powdered catalyst of platinum, palladium, palladium oxide, or mixtures thereof; about 60 to about 76% carbon powder (support) having a particle size less than about 20 m.mu.m and about 20 to about 33% of an inert binder having a particle size of less than about 500 m.mu.m. A sufficient amount of the suspension is poured over a carbon cloth to form a layer of solids about 0.01 to about 0.05 cm thick on the carbon cloth when the electrode is completed. A vacuum was applied to the opposite side of the carbon cloth to remove the liquid and the catalyst layer/cloth assembly is dried and compressed at about 10 to about 50 MPa's. The binder is then sintered in an inert atmosphere to complete the electrode. The electrode is used for the oxidation of sulfur dioxide in a sulfur based hybrid cycle for the decomposition of water.

  6. Effects of the electrolyte composition on the electrode characteristics of rechargeable lithium batteries

    SciTech Connect

    Morita, Masayuki; Ishikawa, Masashi; Matsuda, Yoshiharu

    1995-12-31

    A variety of organic solvent-based electrolytes have been studied for ambient temperature, rechargeable lithium (ion) batteries. The ionic behavior of the electrolyte system was investigated through conductivity measurements. The electrochemical characteristics of carbon-based materials (carbon fiber and graphite) as the negative electrode were examined in different compositions of the organic electrolytes. The electrolyte composition as well as the structure of the electrode material greatly influenced the charge/discharge profiles of the electrode.

  7. Interaction of red blood cells with a polarized electrode: evidence of long-range intermolecular forces.

    PubMed Central

    Gingell, D; Fornes, J A

    1976-01-01

    We have investigated the electrostatic interaction of glutaraldehyde-fixed human red cells with a polarizable electrode carrying a defined surface charge density which can be varied continuously through a wide range. Cells in a dilute salt solution are unable to adhere to the electrode at high negative charge, but at lower negative charge densities they are reversibly adherent and can be forced off by increasing the negative polarization. Near zero electrode charge they become irreversibly stuck to the electrode and cannot be evicted even at maximum electrode polarization. Calculation of the electrostatic repulsive force using measured charge densities indicates the existence of an attractive force which may be acting over several hundred angstroms. PMID:822894

  8. Interaction of red blood cells with a polarized electrode: evidence of long-range intermolecular forces.

    PubMed

    Gingell, D; Fornes, J A

    1976-10-01

    We have investigated the electrostatic interaction of glutaraldehyde-fixed human red cells with a polarizable electrode carrying a defined surface charge density which can be varied continuously through a wide range. Cells in a dilute salt solution are unable to adhere to the electrode at high negative charge, but at lower negative charge densities they are reversibly adherent and can be forced off by increasing the negative polarization. Near zero electrode charge they become irreversibly stuck to the electrode and cannot be evicted even at maximum electrode polarization. Calculation of the electrostatic repulsive force using measured charge densities indicates the existence of an attractive force which may be acting over several hundred angstroms.

  9. Negative and positive cesium ion studies

    NASA Technical Reports Server (NTRS)

    Kuehn, D. G.; Sutliff, D. E.; Chanin, L. M.

    1978-01-01

    Mass spectrometric analyses have been performed on the positive and negative species from discharges in Cs, He-Cs, and He-H2-Cs mixtures. Sampling was conducted through the electrodes of normal glow discharges and from close-spaced heated-cathode conditions, which approximate a cesium thermionic converter. No negative Cs ions were observed for Cs pressures less than .01 torr. Identified species included Cs(+), Cs2(+), Cs(-), and what appeared to be multiply charged ions. Low-mass negative and positive ions attributed to H2 were observed when an He-H2 mixture was also present in the discharge region.

  10. The microstructures and electrochemical performances of La0.6Gd0.2Mg0.2Ni3.0Co0.5-xAlx (x=0-0.5) hydrogen storage alloys as negative electrodes for nickel/metal hydride secondary batteries

    NASA Astrophysics Data System (ADS)

    Li, Rongfeng; Xu, Peizhen; Zhao, Yamin; Wan, Jing; Liu, Xiaofang; Yu, Ronghai

    2014-12-01

    La0.6Gd0.2Mg0.2Ni3.0Co0.5-xAlx (x = 0-0.5) hydrogen storage alloys were prepared by induction melting followed by annealing treatment at 1173 K for 8 h. The effects of substitution Al for Co on the microstructures and electrochemical performances were studied systematically. The structure analyses show that all alloys consist of multiphase structures such as (La, Mg)2Ni7 phase, (La, Mg) Ni3 phase and LaNi5 phase. The abundance of (La, Mg)2Ni7 phase decreases while the abundance of LaNi5 phase and (La, Mg)Ni3 phase increases directly as the Al content increasing. The electrochemical tests show that the maximum discharge capacity of alloy electrodes are almost unchanged when x ≤ 0.2 while the cyclic stability of the alloy electrode are improved significantly after proper amount of Al substitution for Co. The alloy electrode with x = 0.1 exhibits the better balance between discharge capacity and cycling life than any others. Moreover, at the discharge current density of 900 mA g-1, the high rate dischargeability (HRD) of the alloy electrodes decreases with increasing Al substitution and the relative analyses reveal that the charge transfer on alloy surface is more important than the hydrogen diffusion in alloy bulk for the kinetic properties of the alloy electrodes.

  11. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.; Bates, J. Lambert

    1980-01-01

    A ceramic component suitable for preparing MHD generator electrodes having the compositional formula: Y.sub.x (Mg.sub.y Cr.sub.z).sub.w Al.sub.(1-w) O.sub.3 where x=0.9 to 1.05, y=0.02 to 0.2, z=0.8 to 1.05 and w=1.0 to 0.5. The component is resistant to the formation of hydration products in an MHD environment, has good electrical conductivity and exhibits a lower electrochemical corrosion rate than do comparable compositions of lanthanum chromite.

  12. Enzyme nanoband electrodes

    SciTech Connect

    Wang, J.; Naser, N. ); Renschler, C.L. )

    1993-07-01

    Enzyme nanoelectrodes have been constructed by immobilizing glucose oxidase, alcohol oxidase or tyrosinase onto ultrathin carbon films (of 35-50 nm thickness). The enzyme immobilization is accomplished via entrapment within electropolymerized poly(o-phenylenediamine) coatings. Cyclic voltammetry and controlled-potential amperometry are used to characterize the performance of the new nanoscopic biosensors under different preparation and operation conditions. The resulting electrodes offer convenient and rapid measurements of millimolar substrate concentrations, and (to the best of the authors' knowledge) are the smallest enzyme probes reported to date. 10 refs., 7 figs.

  13. Electrodynamic Arrays Having Nanomaterial Electrodes

    NASA Technical Reports Server (NTRS)

    Trigwell, Steven (Inventor); Biris, Alexandru S. (Inventor); Calle, Carlos I. (Inventor)

    2013-01-01

    An electrodynamic array of conductive nanomaterial electrodes and a method of making such an electrodynamic array. In one embodiment, a liquid solution containing nanomaterials is deposited as an array of conductive electrodes on a substrate, including rigid or flexible substrates such as fabrics, and opaque or transparent substrates. The nanomaterial electrodes may also be grown in situ. The nanomaterials may include carbon nanomaterials, other organic or inorganic nanomaterials or mixtures.

  14. Low-Noise Implantable Electrode

    NASA Technical Reports Server (NTRS)

    Lund, G. F.

    1982-01-01

    New implantable electrocardiogram electrode much less sensitive than previous designs to spurious biological potentials. Designed in novel "pocket" configuration, new electrode is intended as sensor for radiotelemetry of biological parameters in experiments on unrestrained subjects. Electrode is esentially squashed cylinder that admits body fluid into interior. Cylinder and electrical lead are made of stainless steel. Spot welding and crimping are used for assembly, rather than soldering.

  15. Electrodes for Semiconductor Gas Sensors.

    PubMed

    Lee, Sung Pil

    2017-03-25

    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode-semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode-semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect.

  16. 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.

  17. 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.

  18. 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.

  19. Molecular dynamics simulations of atomically flat and nanoporous electrodes with a molten salt electrolyte.

    PubMed

    Vatamanu, Jenel; Borodin, Oleg; Smith, Grant D

    2010-01-07

    The electric double layer (EDL) structure and capacitance have been studied for atomically flat and nanoporous conductive electrodes with a molten LiCl electrolyte using an electroactive interface molecular dynamics simulation methodology. For the atomically flat electrodes the electrolyte was observed to form a multilayer structure near the electrode described by exponentially decaying sinusoidal oscillations in ion and charge densities perpendicular to the electrode/electrolyte interface. The differential EDL capacitance vs. electrode potential was found to exhibit "U-shaped" behavior while the EDL capacitance exhibited complex dependence on electrode potential including regions of negative capacitance near zero electrode potential. Increased capacitance and an enhanced degree of electrode-electrolyte interface structure were observed with decreasing temperature. For nanoporous electrodes with both slit and cylindrical pore geometries, the electrolyte was observed to form highly structured alternating charged layers within the electrode nanopores. A maximum in the normalized (per unit electrode area) EDL capacitance was found for pore widths that accommodate several charged layers inside the pores. The observed dependence of capacitance on pore size appears to be a compromise between increasing structure/charge imbalance and decreasing ion density with decreasing pore width/diameter.

  20. Subcutaneous electrode structure

    NASA Technical Reports Server (NTRS)

    Lund, G. F. (Inventor)

    1980-01-01

    A subcutaneous electrode structure suitable for a chronic implant and for taking a low noise electrocardiogram of an active animal, comprises a thin inflexible, smooth disc of stainless steel having a diameter as of 5 to 30 mm, which is sutured in place to the animal being monitored. The disc electrode includes a radially directed slot extending in from the periphery of the disc for approximately 1/3 of the diameter. Electrical connection is made to the disc by means of a flexible lead wire that extends longitudinally of the slot and is woven through apertures in the disc and held at the terminal end by means of a spot welded tab. Within the slot, an electrically insulative sleeve, such as silicone rubber, is placed over the wire. The wire with the sleeve mounted thereon is captured in the plane of the disc and within the slot by means of crimping tabs extending laterally of the slot and over the insulative wire. The marginal lip of the slot area is apertured and an electrically insulative potting material such as silicone rubber, is potted in place overlaying the wire slot region and through the apertures.

  1. Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds.

    PubMed

    DeVries, Lindsay; Scheperle, Rachel; Bierer, Julie Arenberg

    2016-06-01

    Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes.

  2. Electrical stimulation and electrode properties. Part 2: pure metal electrodes.

    PubMed

    Stevenson, Matthew; Baylor, Kelly; Netherton, Brett L; Stecker, Mark M

    2010-12-01

    Electrical stimulation can cause significant damage to clinical electrodes as well as patient injury. In this study, the effects of stimulation on pure metal electrodes were investigated without the complexities introduced by the multiple elements that make up the clinical electrode. As with the clinical electrodes, there was significant decomposition of pure stainless steel anodes with no associated significant changes in the cathodes when stimulation employed long pulse durations. Effects of stimulation were greater when the anode and cathode were closer under constant voltage stimulation but were distance independent under constant current stimulation. High ionic content of the solution also increased the degree of damage to the anode as did the presence of chloride in the solution. Electrode composition also influenced the amount damage to the anode. Platinum and platinum-iridium electrodes showed no damage with any stimulus while stainless steel showed the lowest resistance to corrosion for direct current (DC) stimulation. Tungsten electrodes behaved very differently than stainless steel, decomposing with pulse stimulation and resisting decomposition during DC stimulation because of the formation of surface protective layers. Because platinum was able to maintain high levels of current over time, prolonged stimulation produced dramatic increases in the temperature of the solution; however, even short periods of stimulation were sufficient to produce dramatic changes in pH in the neighborhood of the electrode.

  3. 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.

  4. 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.

  5. Surface analysis of supercapacitor electrodes after long-lasting constant current tests

    NASA Astrophysics Data System (ADS)

    Jänes, Alar; Eskusson, Jaanus; Lust, Enn

    2013-12-01

    FIB-SEM, XPS, TOF-SIMS and electrochemical methods have been used for the characterisation of physical properties and chemical composition of microporous carbide derived carbon electrodes, prepared from TiC at 950 °C (noted as TiC-CDC) after 40000 charge/discharge cycles. Changes in surface chemical composition of TiC-CDC electrodes, includes partial contamination with reaction intermediates (F2, CHO-, CN-, organic radicals), and Al current collectors, like partial dissolution of Al from positively charged electrode and deposition of Al onto the negatively charged TiC-CDC electrode surface, have been analysed.

  6. Radiations cosmiques : danger dans l'Espace

    NASA Astrophysics Data System (ADS)

    Bonnet-Bidaud, J. M.; Dzitko, H.

    2000-06-01

    Au sol, l'atmosphere nous protege plus ou moins bien. Mais dans l'espace ou a bord des avions de ligne, l'homme est directement expose aux rayonnements cosmiques qui peuvent etre mortels. Un veritable frein a la presence humaine prolongee dans l'espace. Une menace que les agences spatiales prennent tres au serieux.

  7. EDM Electrode for Internal Grooves

    NASA Technical Reports Server (NTRS)

    Ramani, V.; Werner, A.

    1985-01-01

    Electroerosive process inexpensive alternative to broaching. Hollow brass electrodes, soldered at one end to stainless-steel holding ring, held in grooves in mandrel. These electrodes used to machine grooves electrically in stainless-steel tube three-eights inch (9.5 millimeters) in diameter. Tool used on tubes already in place in equipment.

  8. Electrochemical photovoltaic cells and electrodes

    DOEpatents

    Skotheim, Terje A.

    1984-01-01

    Improved electrochemical photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes filling pinholes or porous openings in the coatings by electrochemical oxidation of selected monomers to deposit insulating polymer in the openings.

  9. Carbon Cloth Supports Catalytic Electrodes

    NASA Technical Reports Server (NTRS)

    Lu, W. T. P.; Ammon, R. L.

    1983-01-01

    Carbon cloth is starting material for promising new catalytic electrodes. Carbon-cloth electrodes are more efficient than sintered-carbon configuration previously used. Are also chemically stable and require less catalyst--an important economic advantage when catalyst is metal such as platinum.

  10. ELECTROCHEMISTRY OF FUEL CELL ELECTRODES.

    DTIC Science & Technology

    optimization of fuel cell electrodes. Hydrogen oxidation and reduction, the reduction of oxygen, and the oxidation of formic acid, a soluble organic...substance, were selected for these studiees because of their relevance to fuel cell systems and because of their relative simplicity. The electrodes

  11. Reaction profiles in porous electrodes

    NASA Astrophysics Data System (ADS)

    Katan, T.; Carlen, P. J.

    1985-05-01

    An experimental program was conducted to ascertain causes of alkaline zinc electrode shape change and to determine the development of reaction profiles within the pores of porous zinc electrodes. Various analog electrochemical cells were operated to isolate and evaluate the individual processes occurring during charge and discharge. It was found that both edge effects and osmosis can be responsible for the shape change phenomenon.

  12. Activated transport in AMTEC electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kikkert, S.

    1992-01-01

    Transport of alkali, metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. The temperature dependence of the diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and preexponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process.

  13. Non-gassing nickel-cadmium battery electrodes and cells

    NASA Technical Reports Server (NTRS)

    Luksha, E.; Gordy, D. J.

    1972-01-01

    The concept of a negative limited nongassing nickel-cadmium battery was demonstrated by constructing and testing practical size experimental cells of approximately 25 Ah capacity. These batteries operated in a gas-free manner and had measured energy densities of 10-11 Wh/lb. Thirty cells were constructed for extensive testing. Some small cells were tested for over 200 cycles at 100% depth. For example, a small cell with an electrodeposited cadmium active mass on a silver screen still had 55% of its theoretical capacity (initial efficiency was 85%). There was no evidence of deterioration of gassing properties with cycling of the nickel electrodes. The charge temperature was observed to be the most critical variable governing nickel electrode gassing. This variable was shown to be age dependent. Four types of cadmium electrodes were tested: an electrodeposited cadmium active mass on a cadmium or silver substrate, a porous sintered silver substrate based electrode, and a Teflon bonded pressed cadmium electrode. The electrodeposited cadmium mass on a silver screen was found to be the best all-around electrode from a performance point of view and from the point of view of manufacturing them in a size required for a 25 Ah size battery.

  14. Arc/gas electrode

    NASA Technical Reports Server (NTRS)

    Poorman, Richard M. (Inventor); Weeks, Jack L. (Inventor)

    1992-01-01

    A gas/arc electrode is disclosed for use under vacuum conditions where a first housing encloses a second housing, with an end of the second housing extending through an opening in the first housing and having an outlet orifice. Provisions are made for circulating a coolant through the first housing to surround and cool the second housing. An electrical current and a gas, such as argon, as passed through the second housing, with the current flowing through a narrow stream of the ionized gas flowing through the outlet orifice to a workpiece to be treated. The second housing forms a chamber which has a cross sectional area, in a plane perpendicular to the direction of gas flow, of at least ten times the cross sectional area of the outlet orifice such that a gas pressure can be maintained in the chamber to reduce erosion of the chamber walls.

  15. Ribbed electrode substrates

    DOEpatents

    Breault, Richard D.; Goller, Glen J.

    1983-01-01

    A ribbed substrate for an electrochemical cell electrode is made from a mixture of carbon fibers and carbonizable resin and has a mean pore size in the ribs which is 60-75% of the mean pore size of the web portions of the substrate which interconnect the ribs. Preferably the mean pore size of the web portion is 25-45 microns; and, if the substrate includes edge seals parallel to the ribs, the edge seals preferably have a mean pore size no greater than about ten microns. Most preferably the substrate has the same ratio of carbon fibers to polymeric carbon in all areas, including the ribs, webs, and edge seals. A substrate according to the present invention will have better overall performance than prior art substrates and minimizes the substrate thickness required for the substrate to perform all its functions well.

  16. Low resistance electrode construction

    DOEpatents

    Redey, Laszlo; Karell, Eric J.

    2002-01-01

    An electrochemical cell having a cathode and an anode in contact with an electrolyte. Both electrodes or one of them has an electrically conducting non-metal receptacle defining a chamber with a first metal having a melting point in the range of from about room temperature to about 800.degree. C. inside said receptacle chamber. A second metal with a melting point greater than about 800.degree. C. is in contact with the first metal inside the receptacle chamber and extends outside of the receptacle chamber to form a terminal for the anode. The electrolyte may include the oxides, halides or mixtures thereof of one or more of Li, V, U, Al and the lanthanides. Metal may be produced at the cathode during operation of the cell and oxygen or chlorine at the anode.

  17. Electrochromic counter electrode

    DOEpatents

    Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland; Jorgensen, Gary J.

    2005-02-22

    The present invention discloses an amorphous material comprising nickel oxide doped with tantalum that is an anodically coloring electrochromic material. The material of the present invention is prepared in the form of an electrode (200) having a thin film (202) of an electrochromic material of the present invention residing on a transparent conductive film (203). The material of the present invention is also incorporated into an electrochromic device (100) as a thin film (102) in conjunction with a cathodically coloring prior art electrochromic material layer (104) such that the devices contain both anodically coloring (102) and cathodically coloring (104) layers. The materials of the electrochromic layers in these devices exhibit broadband optical complimentary behavior, ionic species complimentary behavior, and coloration efficiency complimentary behavior in their operation.

  18. Gel electrolytes and electrodes

    DOEpatents

    Fleischmann, Sven; Bunte, Christine; Mikhaylik, Yuriy V.; Viner, Veronika G.

    2017-09-05

    Gel electrolytes, especially gel electrolytes for electrochemical cells, are generally described. In some embodiments, the gel electrolyte layers comprise components a) to c). Component a) may be at least one layer of at least one polymer comprising polymerized units of: a1) at least one monomer containing an ethylenically unsaturated unit and an amido group and a2) at least one crosslinker. Component b) may be at least one conducting salt and component c) may be at least one solvent. Electrodes may comprise the components a), d) and e), wherein component a) may be at least one layer of at least one polymer as described herein. Component d) may be at least one electroactive layer and component e) may be at least one ceramic layer. Furthermore, electrochemical cells comprising component a) which may be at least one layer of at least one polymer as described herein, are also provided.

  19. Three-electrode plasma reactor for the removal of toxic gases

    NASA Astrophysics Data System (ADS)

    Gallego, J. L.; Giuliani, L.; Grondona, D.; Minotti, F.

    2015-03-01

    Electrical and spectroscopic measurement for the characterization of a novel three- electrode plasma reactor for the treatment of toxic gases is presented. The three-electrode discharge consists in a dielectric barrier discharge (DBD) combined with a corona discharge (CD). The DBD is generated by applying an alternating high voltage signal between two circular aluminium plate electrodes attached to opposite sides of a disk made of dielectric material. The CD is generated applying a continuous negative high voltage to an external cylindrical mesh electrode, coaxial with the DBD electrode system. The gap between the edge of the DBD system and the mesh electrode is approximately 20 mm wide. Up to five DBD electrode systems can be connected in parallel inside the reactor, axially separated from each other by 30 mm. The electrical characterization consisted in the measurement of the current between the DBD system and the external mesh, and the voltages of the electrodes. In order to understand the dynamics of the streamers, a theoretical determination of the laplacian electric field generated by the biased electrodes was done. Optical emission spectroscopy was performed in the range of wavelengths 280-480 nm, containing the typical spectral bands 2nd positive and 1st negative systems of molecular nitrogen.

  20. Surface-treated carbon electrodes with modified potential of zero charge for capacitive deionization.

    PubMed

    Wu, Tingting; Wang, Gang; Zhan, Fei; Dong, Qiang; Ren, Qidi; Wang, Jianren; Qiu, Jieshan

    2016-04-15

    The potential of zero charge (Epzc) of electrodes can greatly influence the salt removal capacity, charge efficiency and cyclic stability of capacitive deionization (CDI). Thus optimizing the Epzc of CDI electrodes is of great importance. A simple strategy to negatively shift the Epzc of CDI electrodes by modifying commercial activated carbon with quaternized poly (4-vinylpyridine) (AC-QPVP) is reported in this work. The Epzc of the prepared AC-QPVP composite electrode is as negative as -0.745 V vs. Ag/AgCl. Benefiting from the optimized Epzc of electrodes, the asymmetric CDI cell which consists of the AC-QPVP electrode and a nitric acid treated activated carbon (AC-HNO3) electrode exhibits excellent CDI performance. For inverted CDI, the working potential window of the asymmetric CDI cell can reach 1.4 V, and its salt removal capacity can be as high as 9.6 mg/g. For extended voltage CDI, the salt removal capacity of the asymmetric CDI cell at 1.2/-1.2 V is 20.6 mg/g, which is comparable to that of membrane CDI using pristine activated carbon as the electrodes (19.5 mg/g). The present work provides a simple method to prepare highly positively charged CDI electrodes and may pave the way for the development of high-performance CDI cells.

  1. Evaluation of electrode materials for all-copper hybrid flow batteries

    NASA Astrophysics Data System (ADS)

    Leung, Puiki; Palma, Jesus; Garcia-Quismondo, Enrique; Sanz, Laura; Mohamed, M. R.; Anderson, Marc

    2016-04-01

    This work evaluates a number of two- and three-dimensional electrodes for the reactions of an all-copper hybrid flow battery. Half- and full-cell experiments are conducted by minimizing the crossover effect of the copper(II) species. The battery incorporates a Nafion® cation exchange membrane and the negative electrolyte is maintained at the monovalent (colourless) state by the incorporating copper turnings in the electrolyte reservoir. Under such conditions, the half-cell coulombic efficiencies of the negative electrode reactions are all higher than 90% regardless of electrode materials and the state-of-charge (SOC). With charge-discharge cycling the half-cell from a 0% SOC, the coulombic efficiencies of the positive electrode reactions are lower than 76% with the planar carbon electrode, which further decrease in shorter charge-discharge cycles. Polarization and half-cell charge-discharge experiments suggest that the high-surface-area electrodes effectively reduce the overpotentials and improve the coulombic efficiencies of both electrode reactions. When copper fibres and carbon felt are used as the negative and positive electrodes, the average coulombic and voltage efficiencies of an all-copper flow battery are as high as c.a. 99% and c.a. 60% at 50 mA cm-2 for 35 cycles.

  2. Electrode for a lithium cell

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2008-10-14

    This invention relates to a positive electrode for an electrochemical cell or battery, and to an electrochemical cell or battery; the invention relates more specifically to a positive electrode for a non-aqueous lithium cell or battery when the electrode is used therein. The positive electrode includes a composite metal oxide containing AgV.sub.3O.sub.8 as one component and one or more other components consisting of LiV.sub.3O.sub.8, Ag.sub.2V.sub.4O.sub.11, MnO.sub.2, CF.sub.x, AgF or Ag.sub.2O to increase the energy density of the cell, optionally in the presence of silver powder and/or silver foil to assist in current collection at the electrode and to improve the power capability of the cell or battery.

  3. 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.

  4. Composite electrode/electrolyte structure

    DOEpatents

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

    2004-01-27

    Provided is an electrode fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. Onto this electrode in the green state, a green ionic (e.g., electrolyte) film is deposited and the assembly is co-fired at a temperature suitable to fully densify the film while the substrate retains porosity. Subsequently, a catalytic material is added to the electrode structure by infiltration of a metal salt and subsequent low temperature firing. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems.

  5. Smooth electrode and method of fabricating same

    SciTech Connect

    Weaver, Stanton Earl; Kennerly, Stacey Joy; Aimi, Marco Francesco

    2012-08-14

    A smooth electrode is provided. The smooth electrode includes at least one metal layer having thickness greater than about 1 micron; wherein an average surface roughness of the smooth electrode is less than about 10 nm.

  6. Electrodes including a polyphosphazene cyclomatrix, methods of forming the electrodes, and related electrochemical cells

    SciTech Connect

    Gering, Kevin L; Stewart, Frederick F; Wilson, Aaron D; Stone, Mark L

    2014-10-28

    An electrode comprising a polyphosphazene cyclomatrix and particles within pores of the polyphosphazene cyclomatrix. The polyphosphazene cyclomatrix comprises a plurality of phosphazene compounds and a plurality of cross-linkages. Each phosphazene compound of the plurality of phosphazene compounds comprises a plurality of phosphorus-nitrogen units, and at least one pendant group bonded to each phosphorus atom of the plurality of phosphorus-nitrogen units. Each phosphorus-nitrogen unit is bonded to an adjacent phosphorus-nitrogen unit. Each cross-linkage of the plurality of cross-linkages bonds at least one pendant group of one phosphazene compound of the plurality of phosphazene compounds with the at least one pendant group of another phosphazene compound of the plurality of phosphazene compounds. A method of forming a negative electrode and an electrochemical cell are also described.

  7. Advantage of four-electrode over two-electrode defibrillators

    NASA Astrophysics Data System (ADS)

    Bragard, J.; Šimić, A.; Laroze, D.; Elorza, J.

    2015-12-01

    Defibrillation is the standard clinical treatment used to stop ventricular fibrillation. An electrical device delivers a controlled amount of electrical energy via a pair of electrodes in order to reestablish a normal heart rate. We propose a technique that is a combination of biphasic shocks applied with a four-electrode system rather than the standard two-electrode system. We use a numerical model of a one-dimensional ring of cardiac tissue in order to test and evaluate the benefit of this technique. We compare three different shock protocols, namely a monophasic and two types of biphasic shocks. The results obtained by using a four-electrode system are compared quantitatively with those obtained with the standard two-electrode system. We find that a huge reduction in defibrillation threshold is achieved with the four-electrode system. For the most efficient protocol (asymmetric biphasic), we obtain a reduction in excess of 80% in the energy required for a defibrillation success rate of 90%. The mechanisms of successful defibrillation are also analyzed. This reveals that the advantage of asymmetric biphasic shocks with four electrodes lies in the duration of the cathodal and anodal phase of the shock.

  8. Hydrophilic Electrode For An Alkaline Electrochemical Cell, And Method Of Manufacture

    DOEpatents

    Senyarich, Stephane; Cocciantelli, Jean-Michel

    2000-03-07

    A negative electrode for an alkaline electrochemical cell. The electrode comprises an active material and a hydrophilic agent constituted by small cylindrical rods of polyolefin provided with hydrophilic groups. The mean length of the rods is less than 50 microns and the mean diameter thereof is less than 20 microns. A method of manufacturing a negative electrode in which hydrophilic rods are made by fragmenting long polyolefin fibers having a mean diameter of less than 20 microns by oxidizing them, with the rods being mixed with the active material and the mixture being applied to a current conductor.

  9. Reversible and irreversible dilation of lithium-ion battery electrodes investigated by in-situ dilatometry

    NASA Astrophysics Data System (ADS)

    Sauerteig, Daniel; Ivanov, Svetlozar; Reinshagen, Holger; Bund, Andreas

    2017-02-01

    The technique of electrochemical in-situ dilatometry is applied to study the intercalation induced macroscopic expansion of electrodes for lithium-ion batteries. A full cell setup is used to investigate the expansion under real conditions. This method enables in-situ measurement of expansion under defined pressure, using conventional electrodes, separators and electrolytes. To understand the influence of the microstructure, the swelling behavior of different LiNi1/3 Mn1/3 Co1/3 O2 (NMC) positive electrodes and graphite negative electrodes is measured and systematically analyzed. A theoretical approach for assessment of reversible electrode displacement in a full cell is developed, by using a low number of material specific input parameters. Electrochemical in-situ dilatometry is able to show differences in irreversible dilation depending on electrode design and therefore it is a powerful technique for stability and lifetime assessment.

  10. Electrode-distance dependent after-effects of transcranial direct and random noise stimulation with extracephalic reference electrodes.

    PubMed

    Moliadze, Vera; Antal, Andrea; Paulus, Walter

    2010-12-01

    To evaluate the importance of the distance between stimulation electrodes, in various montages, on the ability to induce sustained cortical excitability changes using transcranial direct and random noise stimulation. Twelve healthy subjects participated in four different experimental conditions. The stimulation electrode was always placed over the primary motor cortex; the reference electrode was placed at the contralateral orbit or at the ipsilateral/contralateral arm. MEPs were recorded in order to measure changes in cortical excitability over time. The distance between the two electrodes correlates negatively with the duration and magnitude of induced after-effects. In particular when using extracephalic reference electrodes with transcranial electric stimulation techniques, the stimulation intensity has to be adapted to account for interelectrode distance. Electrode distance plays a critical role in the induction for stimulation after-effects in tDCS and tRNS studies, and must be taken into account in future studies and also when making comparisons with the published literature. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  11. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions. [Patent application

    DOEpatents

    Mrazek, F.C.; Smaga, J.A.; Battles, J.E.

    1981-01-19

    A positive electrode for a secondary electrochemical cell is described wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

  12. Modified carbon surfaces as "organic electrodes" that exhibit conductance switching.

    PubMed

    Solak, Ali Osman; Eichorst, Laura R; Clark, William J; McCreery, Richard L

    2003-01-15

    Glassy carbon (GC) surfaces modified with monolayers of biphenyl and nitrobiphenyl molecules were examined as voltammetric electrodes for ferrocene, benzoquinone, and tetracyanoquinodimethane electrochemistry in acetonitrile. The modified electrodes exhibited slower electron transfer than unmodified GC, by factors that varied with the monolayer and redox system. However, after a negative potential excursion to approximately -2.0 V versus Ag+/Ag, the modified electrodes exhibited much faster electron-transfer kinetics, approaching those observed on unmodified GC. The effect is attributed to an apparently irreversible structural change in the biphenyl or nitrobiphenyl monolayer, which increases the rate of electron tunneling. The transition to the "ON" state is associated with electron injection into the monolayer similar to that observed in previous spectroscopic investigations and causes a significant decrease in the calculated HOMO-LUMO gap for the monolayer molecule. Once the monolayer is switched ON, it supports rapid electron exchange with outer-sphere redox systems, but not with dopamine, which requires adsorption to the GC surface. The increase in electron-transfer rate with electron injection is consistent with an increase in electron tunneling rate through the monolayer, caused by a significant decrease in tunneling barrier height. The ON electrode can reduce biphenyl- or nitrobiphenyldiazonium reagent in solution to permit formation of a second modification layer of biphenyl or nitrobiphenyl molecules. This "double derivatization" procedure was used to prepare tetraphenyl- and nitrotetraphenyl-modified electrodes, which exhibit significantly slower electron transfer than their biphenyl and nitrobiphenyl counterparts. A "switching" electrode may have useful properties for electroanalytical applications and possibly in electrocatalysis. In addition, the ON state represents an "organic electrode" in which electron transfer occurs at an interface between an

  13. Preset Electrodes for Electrical-Discharge Machining

    NASA Technical Reports Server (NTRS)

    Coker, Bill E.

    1987-01-01

    New electrode holder for electrical-discharge machining (EDM) provides for repeatable loading and setting of many electrodes. New holder is rotating-index tool carrying six, eight, or more electrodes. Before use, all electrodes set with aid of ring surrounding tool, and locked in position with screws. When electrode replaced, EDM operator pulls spring-loaded pin on tool so it rotates about center pin. Fresh electrode then rotated into position against workpiece.

  14. Etude de la génération de bulles dans les hydrocarbures liquides générées par les impulsio.ns de Trichel

    NASA Astrophysics Data System (ADS)

    Kattan, R.; Bonifaci, N.; Denat, A.

    1991-07-01

    The electrical conduction of purified non polar liquids with point-plane electrode geometry was studied as a function of various parameters. For negative polarity of the point a pulse regime have been observed which bears a great similarity with the Trichel pulses. Below the critical pressure of the liquids, bubble formation was correlated with current pulse. In this paper we present a study of the generation and dynamics of the bubble as function of various parameters: injected energy, liquid pressure, liquid properties. The transition to a streamer phenomenon is also investigated. Une étude de la conduction électrique des liquides non polaires très purs, dans une géométrie pointe-plan, a mis en évidence l'apparition d'un régime très régulier d'impulsions de courant en polarité négative de la pointe. Ce régime s'explique par un mécanisme d'avalanches électroniques en phase liquide dans la zone de champ intense qui induit la formation d'une bulle unique. L'énergie injectée est uniquement fonction du rayon de courbure de la pointe. On présente une étude de la génération et de la dynamique de cette bulle en fonction de la nature du liquide, de la pression hydrostatique et de l'énergie injectée. On montre que la dynamique de la bulle est contrôlée par l'inertie du liquide, que sa taille maximale est proportionnelle à l'énergie injectée pour une pression donnée et que cette énergie sert essentiellement à vaporiser le liquide. Dans les conditions où la durée de vie de la bulle et donc sa taille sont élevées, l'impulsion initiale de courant est suivie par des décharges électriques dans la bulle et il y a début de propagation d'un canal gazeux vers le plan (streamer !).

  15. Porous carbonaceous electrode structure and method for secondary electrochemical cell

    DOEpatents

    Kaun, Thomas D.

    1977-03-08

    Positive and negative electrodes are provided as rigid, porous carbonaceous matrices with particulate active material fixedly embedded. Active material such as metal chalcogenides, solid alloys of alkali metal or alkaline earth metals along with other metals and their oxides in particulate form are blended with a thermosetting resin and a solid volatile to form a paste mixture. Various electrically conductive powders or current collector structures can be blended or embedded into the paste mixture which can be molded to the desired electrode shape. The molded paste is heated to a temperature at which the volatile transforms into vapor to impart porosity as the resin begins to cure into a rigid solid structure.

  16. Current collector geometry and mixing in liquid metal electrodes

    NASA Astrophysics Data System (ADS)

    Ashour, Rakan; Kelley, Douglas

    2015-11-01

    Liquid metal batteries are emerging as an efficient and cost effective technology for large-scale energy storage on electrical grids. In these batteries, critical performance related factors such as the limiting current density and life cycle are strongly influenced by fluid mixing and transport of electrochemical species to and from the electrode-electrolyte interface. In this work, ultrasound velocimetry is used to investigate the role of negative current collector location on the induced velocity, flow pattern, and mixing time in liquid metal electrodes. Ultrasound velocity measurements are obtained at a range of operating current densities. Furthermore, a comparison between velocity profiles produced by current collectors with different sizes is also presented.

  17. Electronic Transport of a Molecular Photoswitch with Graphene Nanoribbon Electrodes

    NASA Astrophysics Data System (ADS)

    Wu, Qiu-Hua; Zhao, Peng; Liu, De-Sheng

    2014-05-01

    Based on non-equilibrium Green's function formalism and density functional theory calculations, we investigate the electronic transport properties of 15,16-dinitrile dihydropyrene/cyclophanediene bridged between two zigzag graphene nanoribbon electrodes. Our results demonstrate that the system can exhibit good switching behavior with the maximum on-off ratio high up to 146 which is improved dramatically compared with the case of gold electrodes. Moreover, an obvious negative differential resistance behavior occurs at 0.3 V, making the system have more potential in near future molecular circuits.

  18. MHD Electrode and wall constructions

    DOEpatents

    Way, Stewart; Lempert, Joseph

    1984-01-01

    Electrode and wall constructions for the walls of a channel transmitting the hot plasma in a magnetohydrodynamic generator. The electrodes and walls are made of a plurality of similar modules which are spaced from one another along the channel. The electrodes can be metallic or ceramic, and each module includes one or more electrodes which are exposed to the plasma and a metallic cooling bar which is spaced from the plasma and which has passages through which a cooling fluid flows to remove heat transmitted from the electrode to the cooling bar. Each electrode module is spaced from and electrically insulated from each adjacent module while interconnected by the cooling fluid which serially flows among selected modules. A wall module includes an electrically insulating ceramic body exposed to the plasma and affixed, preferably by mechanical clips or by brazing, to a metallic cooling bar spaced from the plasma and having cooling fluid passages. Each wall module is, similar to the electrode modules, electrically insulated from the adjacent modules and serially interconnected to other modules by the cooling fluid.

  19. In vivo electrode implanting system

    NASA Technical Reports Server (NTRS)

    Collins, Jr., Earl R. (Inventor)

    1989-01-01

    A cylindrical intramuscular implantable electrode is provided with a strip of fabric secured around it. The fabric is woven from a polyester fiber having loops of the fiber protruding. The end of the main cylindrical body is provided with a blunt conductive nose, and the opposite end is provided with a smaller diameter rear section with an annular groove to receive tips of fingers extending from a release tube. The fingers are formed to spring outwardly and move the fingertips out of the annular groove in order to release the electrode from the release tube when a sheath over the electrode is drawn back sufficiently. The sheath compresses the fingers of the release tube and the fabric loops until it is drawn back. Muscle tissue grows into the loops to secure the electrode in place after the sheath is drawn back. The entire assembly of electrode, release tube and sheath can be inserted into the patient's muscle to the desired position through a hypodermic needle. The release tube may be used to manipulate the electrode in the patient's muscle to an optimum position before the electrode is released.

  20. Arc electrode interaction study

    NASA Technical Reports Server (NTRS)

    Zhou, X.; Berns, D.; Heberlein, J.

    1994-01-01

    The project consisted of two parts: (1) the cathode interaction studies which were a continuation of previous work and had the objective of increasing our understanding of the microscopic phenomena controlling cathode erosion in arc jet thrusters, and (2) the studies of the anode attachment in arc jet thrusters. The cathode interaction studies consisted of (1) a continuation of some modeling work in which the previously derived model for the cathode heating was applied to some specific gases and electrode materials, and (2) experimental work in which various diagnostics was applied to the cathode. The specific diagnostics used were observation of the cathode tip during arcing using a Laser Strobe Video system in conjunction with a tele-microscope, a monochromator with an optical multichannel analyzer for the determination of the cathode temperature distribution, and various ex situ materials analysis methods. The emphasis of our effort was shifted to the cathode materials analysis because a parallel project was in place during the second half of 1993 with a visiting scientist pursuing arc electrode materials studies. As a consequence, the diagnostic investigations of the arc in front of the cathode had to be postponed to the first half of 1994, and we are presently preparing these measurements. The results of last year's study showed some unexpected effects influencing the cathode erosion behavior, such as increased erosion away from the cathode tip, and our understanding of these effects should improve our ability to control cathode erosion. The arc jet anode attachment studies concentrated on diagnostics of the instabilities in subsonic anode attachment arc jet thrusters, and were supplemental measurements to work which was performed by one of the authors who spent the summer as an intern at NASA Lewis Research Center. A summary of the results obtained during the internship are included because they formed an integral part of the study. Two tasks for 1994, the

  1. Activated transport in AMTEC electrodes

    SciTech Connect

    Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O`Connor, D.; Kikkert, S.

    1992-07-01

    Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

  2. Activated transport in AMTEC electrodes

    SciTech Connect

    Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O'Connor, D.; Kikkert, S.

    1992-01-01

    Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

  3. Conductive lithium storage electrode

    DOEpatents

    Chiang, Yet-Ming; Chung, Sung-Yoon; Bloking, Jason T; Andersson, Anna M

    2014-10-07

    A compound comprising a composition A.sub.x(M'.sub.1-aM''.sub.a).sub.y(XD.sub.4).sub.z, A.sub.x(M'.sub.1-aM''.sub.a).sub.y(DXD.sub.4).sub.z, or A.sub.x(M'.sub.1-aM''.sub.a).sub.y(X.sub.2D.sub.7).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(XD.sub.4).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(DXD.sub.4).sub.z, or (A.sub.1-aM''.sub.a).sub.xM'.sub.y(X.sub.2D.sub.7).sub.z. In the compound, A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen, 0.0001electrodes and storage batteries.

  4. Lead acid battery performance and cycle life increased through addition of discrete carbon nanotubes to both electrodes

    NASA Astrophysics Data System (ADS)

    Sugumaran, Nanjan; Everill, Paul; Swogger, Steven W.; Dubey, D. P.

    2015-04-01

    Contemporary applications are changing the failure mechanisms of lead acid batteries. Sulfation at the negative electrode, acid stratification, and dendrite formation now precede positive electrode failures such as grid corrosion and active material shedding. To attenuate these failures, carbon has been explored as a negative electrode additive to increase charge acceptance, eliminate sulfation, and extend cycle life. Frequently, however, carbon incorporation decreases paste density and hinders manufacturability. Discrete carbon nanotubes (dCNT), also known as Molecular Rebar®, are lead acid battery additives which can be stably incorporated into either electrode to increase charge acceptance and cycle life with no change to paste density and without impeding the manufacturing process. Here, full-scale automotive batteries containing dCNT in the negative electrode or both negative and positive electrodes are compared to control batteries. dCNT batteries show little change to Reserve Capacity, improved Cold Cranking, increased charge acceptance, and enhanced overall system efficiency. Life cycle tests show >60% increases when dCNT are incorporated into the negative electrode (HRPSoC/SBA) and up to 500% when incorporated into both electrodes (SBA), with water loss per cycle reduced >20%. Failure modes of cycled batteries are discussed and a hypothesis of dCNT action is introduced: the dCNT/Had Overcharge Reaction Mechanism.

  5. Apparatus for focused electrode induced polarization logging

    SciTech Connect

    Vinegar, H.J.; Waxman, M.H.

    1986-04-15

    An induced polarization logging tool is described for measuring parameters of a formation surrounding a borehole. The logging tool consists of: a non-conductive logging sonde; a plurality of electrodes disposed on the sonde, the electrodes including at least a survey current electrode and guard electrodes disposed on opposite sides of the survey current electrode, a non-polarizing voltage measuring electrode, a non-polarizing voltage reference electrode and a current return electrode, both the voltage reference and current return electrodes being located a greater distance from the survey current electrode than the guard electrodes; means connected to the survey current electrode and the guard electrodes for generating a signal representative of the potential difference in the formation between the survey current electrode and the guard electrodes; first control means directly coupled to the survey current electrode, the first control means controlling the current flow to the survey current electrode in response to the potential difference signal; a second control means directly coupled to the guard electrodes to control the current flow to the guard electrodes in response to the potential difference signal; a source of alternating current located at the surface, one end of the source being coupled to the two control means and the other to the current return electrode, the source supplying alternating current at various discrete frequencies between substantially 0.01 and 100 Hz; measurement means directly coupled to the voltage measurement and survey current electrodes to measure the amplitude and phase of the voltage induced in the formation and the amplitude and phase of the current flow to the survey electrode; and transmission means for transmitting the measurements to the surface.

  6. All-solid electrodes with mixed conductor matrix

    DOEpatents

    Huggins, Robert A.; Boukamp, Bernard A.

    1984-01-01

    Alkali metal based electrochemical cells offer a great deal of promise for applications in many areas such as electric vehicles and load leveling purposes in stationary power plants. Lithium is an attractive candidate as the electroactive species in such cells since lithium is very electropositive, abundant and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and normally is operated at elevated temperatures. The subject invention provides an electrochemical cell in one embodiment of which lithium is the electroactive species. The cell comprises an electrolyte, a positive electrode, and a negative electrode, either or both of which is an all-solid, composite microstructural electrode containing both a reactant phase and a mixed ionic-electronic conducting phase. The cells of the subject invention exhibit improved kinetic features, current and power densities. Repeated charging and discharging of these cells can be accomplished without appreciable loss of capacity.

  7. Cycling behavior of NCM523/graphite lithium-ion cells in the 3–4.4 V range: Diagnostic studies of full cells and harvested electrodes

    SciTech Connect

    Gilbert, James A.; Bareño, Javier; Spila, Timothy; Trask, Stephen E.; Miller, Dean J.; Polzin, Bryant J.; Jansen, Andrew N.; Abraham, Daniel P

    2016-09-22

    Energy density of full cells containing layered-oxide positive electrodes can be increased by raising the upper cutoff voltage above the current 4.2 V limit. In this article we examine aging behavior of cells, containing LiNi0.5Co0.2Mn0.3O2 (NCM523)-based positive and graphite-based negative electrodes, which underwent up to ~400 cycles in the 3-4.4 V range. Electrochemistry results from electrodes harvested from the cycled cells were obtained to identify causes of cell performance loss; these results were complemented with data from X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) measurements. Our experiments indicate that the full cell capacity fade increases linearly with cycle number and results from irreversible lithium loss in the negative electrode solid electrolyte interphase (SEI) layer. The accompanying electrode potential shift reduces utilization of active material in both electrodes and causes the positive electrode to cycle at higher states-of-charge. Here, full cell impedance rise on aging arises primarily at the positive electrode and results mainly from changes at the electrode-electrolyte interface; the small growth in negative electrode impedance reflects changes in the SEI layer. Our results indicate that cell performance loss could be mitigated by modifying the electrode-electrolyte interfaces through use of appropriate electrode coatings and/or electrolyte additives.

  8. Cycling behavior of NCM523/graphite lithium-ion cells in the 3–4.4 V range: Diagnostic studies of full cells and harvested electrodes

    DOE PAGES

    Gilbert, James A.; Bareno, Javier; Spila, Timothy; ...

    2016-09-22

    Energy density of full cells containing layered-oxide positive electrodes can be increased by raising the upper cutoff voltage above the current 4.2 V limit. In this article we examine aging behavior of cells, containing LiNi0.5Co0.2Mn0.3O2 (NCM523)-based positive and graphite-based negative electrodes, which underwent up to ~400 cycles in the 3-4.4 V range. Electrochemistry results from electrodes harvested from the cycled cells were obtained to identify causes of cell performance loss; these results were complemented with data from X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) measurements. Our experiments indicate that the full cell capacity fade increases linearly withmore » cycle number and results from irreversible lithium loss in the negative electrode solid electrolyte interphase (SEI) layer. The accompanying electrode potential shift reduces utilization of active material in both electrodes and causes the positive electrode to cycle at higher states-of-charge. Here, full cell impedance rise on aging arises primarily at the positive electrode and results mainly from changes at the electrode-electrolyte interface; the small growth in negative electrode impedance reflects changes in the SEI layer. Our results indicate that cell performance loss could be mitigated by modifying the electrode-electrolyte interfaces through use of appropriate electrode coatings and/or electrolyte additives.« less

  9. Thin metal electrode for AMTEC

    NASA Technical Reports Server (NTRS)

    Williams, Roger M. (Inventor); Wheeler, Bob L. (Inventor); Jefferies-Nakamura, Barbara (Inventor); Lamb, James L. (Inventor); Bankston, C. Perry (Inventor); Cole, Terry (Inventor)

    1989-01-01

    An electrode having higher power output is formed of a thin, porous film (less than 1 micrometer) applied to a beta-alumina solid electrolyte (BASE). The electrode includes an open grid, current collector such as a series of thin, parallel, grid lines applied to the thin film and a plurality of cross-members such as loop of metal wire surrounding the BASE tube. The loops are electrically connected by a bus wire. The overall impedance of the electrode considering both the contributions from the bulk BASE and the porous electrode BASE interface is low, about 0.5 OHM/cm.sup.2 and power densities of over 0.3 watt/cm.sup.2 for extended periods.

  10. Research on rechargeable oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Giner, J.; Malachesky, P. A.; Holleck, G.

    1971-01-01

    Studies were carried out on a number of factors which may influence the behavior of the platinum electrocatalyst of oxygen electrodes for use in rechargeable metal-oxygen batteries or hydrogen-oxygen fuel cells. The effects of pretreatments for various potentials and added ionic species, which could be present in such systems, were studied with reguard to: (1) the state of surface oxidation, (2) platinum dissolution, (3) the kinetics of oxygen evolution and reduction (including the role of hydrogen peroxide), and (4) changes in porous electrode structure. These studies were carried out on smooth platinum, platinized platinum, and Teflon-bonded platinum black electrodes in carefully purified electrolyte solutions. The main factors which appear to affect rechargeable oxygen electrode performance and life are: (1) the buildup of a refractory anodic layer on extended cycling, and (2) the dissolution of platinum.

  11. Method of making biocompatible electrodes

    DOEpatents

    Wollam, John S.

    1992-01-01

    A process of improving the sensing function of biocompatible electrodes and the product so made are disclosed. The process is designed to alter the surfaces of the electrodes at their tips to provide increased surface area and therefore decreased contact resistance at the electrode-tissue interface for increased sensitivity and essentially includes rendering the tips atomically clean by exposing them to bombardment by ions of an inert gas, depositing an adhesion layer on the cleaned tips, forming a hillocked layer on the adhesion layer by increasing the temperature of the tips, and applying a biocompatible coating on the hillocked layer. The resultant biocompatible electrode is characterized by improved sensitivity, minimum voltage requirement for organ stimulation and a longer battery life for the device in which it is employed.

  12. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, B.; Bolstad, J.J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the present invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process. 4 figs.

  13. The secondary alkaline zinc electrode

    NASA Astrophysics Data System (ADS)

    McLarnon, Frank R.; Cairns, Elton J.

    1991-02-01

    The worldwide studies conducted between 1975 and 1990 with the aim of improving cell lifetimes of secondary alkaline zinc electrodes are overviewed. Attention is given the design features and characteristics of various secondary alkaline zinc cells, including four types of zinc/nickel oxide cell designs (vented static-electrolyte, sealed static-electrolyte, vibrating-electrode, and flowing-electrolyte); two types of zinc/air cells (mechanically rechargeable consolidated-electrode and mechanically rechargeable particulate-electrode); zinc/silver oxide battery; zinc/manganese dioxide cell; and zinc/ferric cyanide battery. Particular consideration is given to recent research in the fields of cell thermodynamics, zinc electrodeposition, zinc electrodissolution, zinc corrosion, electrolyte properties, mathematical and phenomenological models, osmotic pumping, nonuniform current distribution, and cell cycle-life perforamnce.

  14. Thin film fuel cell electrodes.

    NASA Technical Reports Server (NTRS)

    Asher, W. J.; Batzold, J. S.

    1972-01-01

    Earlier work shows that fuel cell electrodes prepared by sputtering thin films of platinum on porous vycor substrates avoid diffusion limitations even at high current densities. The presented study shows that the specific activity of sputtered platinum is not unusually high. Performance limitations are found to be controlled by physical processes, even at low loadings. Catalyst activity is strongly influenced by platinum sputtering parameters, which seemingly change the surface area of the catalyst layer. The use of porous nickel as a substrate shows that pore size of the substrate is an important parameter. It is noted that electrode performance increases with increasing loading for catalyst layers up to two microns thick, thus showing the physical properties of the sputtered layer to be different from platinum foil. Electrode performance is also sensitive to changing differential pressure across the electrode. The application of sputtered catalyst layers to fuel cell matrices for the purpose of obtaining thin total cells appears feasible.

  15. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, Bora; Bolstad, James J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the pesent invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process.

  16. 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.

  17. On Multiplying Negative Numbers.

    ERIC Educational Resources Information Center

    Crowley, Mary L.; Dunn, Kenneth A.

    1985-01-01

    Comments on the history of negative numbers, some methods that can be used to introduce the multiplication of negative numbers to students, and an explanation of why the product of two negative numbers is a positive number are included. (MNS)

  18. Eight electrode optical readout gap

    DOEpatents

    Boettcher, Gordon E.; Crain, Robert W.

    1985-01-01

    A protective device for a plurality of electrical circuits includes a pluity of isolated electrodes forming a gap with a common electrode. An output signal, electrically isolated from the circuits being monitored, is obtained by a photosensor viewing the discharge gap through an optical window. Radioactive stabilization of discharge characteristics is provided for slowly changing voltages and carbon tipped dynamic starters provide desirable discharge characteristics for rapidly varying voltages. A hydrogen permeation barrier is provided on external surfaces of the device.

  19. Electrochemistry at Very Small Electrodes.

    DTIC Science & Technology

    1985-09-01

    Contract N00014-79-C-0862. This contract has a peculiar history. It originated in 1979. under the title "Studies in Cathodic Stripping Voltammetry and...The second category involved studies of cathodic stripping voltammetry of various materials, primarily at silver electrodes. Work carried out... Cathodic Stripping Voltammetry at a Rotating Disc Electrode", K. Shimizu and R.A. Osteryoung, February, 1981. * 4. "Electrochemical Behavior of Sulfide

  20. Bifunctional oxygen/air electrodes

    NASA Astrophysics Data System (ADS)

    Jörissen, Ludwig

    A selective review on the materials and construction principles used for bifunctional oxygen/air electrodes is given. The discussion emphasizes the catalytically active materials used for the construction of these electrodes, which are a key component in electrically rechargeable air breathing electrochemical systems. Whereas, in acid electrolytes normally noble metal catalysts must be used, there is a possibility to use less expensive transition metal oxides in alkaline electrolytes. Typical transition metal oxides have the perovskite, pyrochlore and spinel structure.

  1. Nanosecond plasma-mediated electrosurgery with elongated electrodes

    NASA Astrophysics Data System (ADS)

    Vankov, Alexander; Palanker, Daniel

    2007-06-01

    Progress in interventional medicine is associated with the development of more delicate and less invasive surgical procedures, which requires more precise and less traumatic, yet affordable, surgical instruments. Previously we reported on the development of the pulsed electron avalanche knife for dissection of soft tissue in liquid media using the 100 ns plasma-mediated electric discharges applied via a 25 μm disk microelectrode. Cavitation bubbles accompanying explosive vaporization of the liquid medium in front of such a pointed electrode produced a series of craters that did not always merge into a continuous cut. In addition, this approach of surface ablation provided a limited depth of cutting. Application of an elongated electrode capable of cutting with its edge rather than just with its pointed apex faces a problem of nonuniformity of the electric field on a nonspherical electrode. In this article we explore dynamics of the plasma-mediated nanosecond discharges in liquid medium in positive and negative polarities and describe the geometry of an electrode that provides a sufficiently uniform electric field along an extended edge of a surgical probe. A highly enhanced and uniform electric field was obtained on very sharp (2.5 μm) exposed edges of a planar electrode insulated on its flat sides. Uniform ionization and simultaneous vaporization was obtained along the whole edge of such a blade with 100 ns pulses at 4-6 kV. A continuous cutting rate of 1 mm/s in the retina and in soft membranes was achieved at a pulse repetition rate of 100 Hz. The collateral damage zone at the edges of incision did not exceed 80 μm. Negative polarity was found advantageous due to the lower rate of electrode erosion and due to better spatial confinement of the plasma-mediated discharge in liquid.

  2. New β-Cyclodextrin Entrapped in Polyethyleneimine Film-Modified Electrodes for Pharmaceutical Compounds Determination

    PubMed Central

    Fritea, Luminţa; Tertiş, Mihaela; Cristea, Cecilia; Săndulescu, Robert

    2013-01-01

    The electrochemical behavior of ascorbic acid and uric acid on glassy carbon bare electrodes and ones modified with β-cyclodextrin entrapped in polyethyleneimine film has been investigated using square wave voltammetry. The electrode modification was achieved in order to separate the voltammetric peaks of ascorbic acid and uric acid when present in the same solution. On the modified electrodes the potential of the oxidation peak of the ascorbic acid was shifted to more negative values by over 0.3 V, while in the case of uric acid, the negative potential shift was about 0.15 V compared to the bare glassy carbon electrode. When the two compounds were found together in the solution, on the bare electrode only a single broad signal was observed, while on the modified electrode the peak potentials of these two compounds were separated by 0.4 V. When the uric acid concentration remained constant, the peak intensity of the ascorbic acid is increased linearly with the concentration (r2 = 0.996) and when the ascorbic acid concentration remains constant, the peak intensity of the uric acid increased linearly with the concentration (r2 = 0.992). FTIR measurements supported the formation of inclusion complexes. In order to characterize the modification of the electrodes microscopic studies were performed. The modified electrodes were successfully employed for the determination of ascorbic acid in pharmaceutical formulations with a detection limit of 0.22 μM. PMID:24287544

  3. Plasma driven by helical electrodes

    NASA Astrophysics Data System (ADS)

    Akcay, Cihan; Finn, John; Nebel, Richard; Barnes, Daniel

    2016-10-01

    A novel plasma state, obtained by applying a helical voltage at the wall with a uniform axial magnetic field, is studied by means of zero-pressure resistive MHD simulations in a periodic cylinder. The radial magnetic field at the wall is taken to be zero. For a small helical electrode voltage, the helical perturbation in the plasma is small and localized to the edge. Beyond a critical electrode voltage, there is a bifurcation to the newly discovered state, which is a single-helicity Ohmic equilibrium with the same helicity as the electrodes, i.e., the fields depend only on radius and mθ - nφ , where θ and φ = z / R are the poloidal and toroidal angles. For electrostatic driving with m = 1 , the mean magnetic field (m = n = 0) has field line safety factor q(r) equal to the pitch of the electrodes m / n = 1 / n except near the edge, where it monotonically increases an amount of order unity. The plasma is force-free in the interior. Near the edge, however, the current crosses the field lines to enter and exit through the helical electrodes. A large helical plasma flow related Pfirsch-Schlüter-like currents exist in this edge vicinity. Applications to current drive in tokamaks, as well as to straight plasmas with endcap electrodes are discussed.

  4. Electrode kinetics of oxygen reduction - A theoretical and experimental analysis of the rotating ring-disc electrode method

    NASA Technical Reports Server (NTRS)

    Hsueh, K.-L.; Chin, D.-T.; Srinivasan, S.

    1983-01-01

    In order to calculate most of the rate constants for the intermediate formation of H2O2 in the electroreduction of O2 to H2O, the theoretical treatments of the rotating ring-disc electrode method by Damjanovic et al. (1966, 1967), Bagotskii et al. (1968, 1969), and Wroblowa et al. (1976) are modified. Rotating ring-disc electrode experimental data obtained for O2 reduction in Pt in 0.55 M H2SO4 are used to illustrate the calculations of rate constants according to the above theoretical treatments. A simple reaction model as proposed by the first author is consistent with the experimental data. The results indicate that O2 (97 percent) reduces to H2O in a direct four-electron transfer reaction. The adsorption of O2 is probably the rate-determining step in the potential region more negative than 0.5 V vs. reversible hydrogen electrode.

  5. Electrode kinetics of oxygen reduction - A theoretical and experimental analysis of the rotating ring-disc electrode method

    NASA Technical Reports Server (NTRS)

    Hsueh, K.-L.; Chin, D.-T.; Srinivasan, S.

    1983-01-01

    In order to calculate most of the rate constants for the intermediate formation of H2O2 in the electroreduction of O2 to H2O, the theoretical treatments of the rotating ring-disc electrode method by Damjanovic et al. (1966, 1967), Bagotskii et al. (1968, 1969), and Wroblowa et al. (1976) are modified. Rotating ring-disc electrode experimental data obtained for O2 reduction in Pt in 0.55 M H2SO4 are used to illustrate the calculations of rate constants according to the above theoretical treatments. A simple reaction model as proposed by the first author is consistent with the experimental data. The results indicate that O2 (97 percent) reduces to H2O in a direct four-electron transfer reaction. The adsorption of O2 is probably the rate-determining step in the potential region more negative than 0.5 V vs. reversible hydrogen electrode.

  6. 21 CFR 882.1340 - Nasopharyngeal electrode.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nasopharyngeal electrode. 882.1340 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1340 Nasopharyngeal electrode. (a) Identification. A nasopharyngeal electrode is an electrode which is temporarily placed in the...

  7. 21 CFR 882.1340 - Nasopharyngeal electrode.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nasopharyngeal electrode. 882.1340 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1340 Nasopharyngeal electrode. (a) Identification. A nasopharyngeal electrode is an electrode which is temporarily placed in the...

  8. 21 CFR 882.1340 - Nasopharyngeal electrode.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nasopharyngeal electrode. 882.1340 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1340 Nasopharyngeal electrode. (a) Identification. A nasopharyngeal electrode is an electrode which is temporarily placed in the...

  9. 21 CFR 882.1320 - Cutaneous electrode.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cutaneous electrode. 882.1320 Section 882.1320...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1320 Cutaneous electrode. (a) Identification. A cutaneous electrode is an electrode that is applied directly to a patient's skin either to...

  10. 21 CFR 882.1340 - Nasopharyngeal electrode.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nasopharyngeal electrode. 882.1340 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1340 Nasopharyngeal electrode. (a) Identification. A nasopharyngeal electrode is an electrode which is temporarily placed in the...

  11. 21 CFR 882.1340 - Nasopharyngeal electrode.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nasopharyngeal electrode. 882.1340 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1340 Nasopharyngeal electrode. (a) Identification. A nasopharyngeal electrode is an electrode which is temporarily placed in the...

  12. Characteristic electron transport on pyridine-linked molecular devices with graphene nanoribbons electrodes and gold electrodes

    NASA Astrophysics Data System (ADS)

    Li, Jie; Zhou, Yi; Zhang, Leining; Li, Hui

    2016-09-01

    The electrodes in the molecular devices play a crucial role in creating functional organic electronic devices. We employed the first-principles calculations to investigate the conjugated pyridine-terminated molecule-4, 4‧-vinylenedipyridine attached to monolayer zigzag graphene nanoribbons (ZGNRs) and Au electrodes. Results show that the ZGNRs-based device exhibits excellent electrical properties. It has larger equilibrium conductance or stronger transmission capacity due to higher strength of individual channel and stronger delocalization of electronic states at the Fermi level. The transmission of two devices near the Fermi level is influenced by resonant electron transport through the discrete energy and the edge states. Comparatively, different from the rising trend of gold-based device with the increasing voltage, the current of the device with ZGNRs electrodes changes in a completely different way with the augment of the applied voltage, exhibiting a negative differential resistance effect unexpectedly. The changing trends of the current through two devices are elucidated by the evolution of the transmission peak nearest to the Fermi level.

  13. Cyclic voltammetry of aquocobalamin on clay-modified electrodes

    SciTech Connect

    Borek, V.; Morra, M.J.

    1998-07-15

    Halogenated synthetic compounds are widespread contaminants of the environment. Although corrinoids reductively dehalogenate synthetic contaminants in solution, the redox behavior of sorbed tetrapyrroles has received limited attention. Colloidal clay suspensions were prepared as Ca{sup 2+} forms of hectorite (SHCa-1), montmorillonite (SWy-1, Syn-1, and SAz-1), and vermiculite (VTx-1) and spin coated on platinum electrodes. Cyclic voltammetry was performed with the clay-modified electrodes immersed in buffered solutions containing 1.0 mM aquocobalamin. Aquocobalamin in the presence of vermiculite-coated electrodes displayed the same cathodic and anodic peak potentials as unmodified electrodes immersed in aquocobalamin solutions. All other clay-modified electrodes shifted cathodic peaks to more negative values, while anodic peak shifts varied with the clay. Hectorite caused the largest shift in formal redox potential as compared to aquocobalamin in solution. The redox behavior of aquocobalamin as modified by sorption to clay minerals potentially affects dehalogenation rates of synthetic organic compounds in the environment. Clays lowering the formal redox potential of the tetrapyrrole create a potentially more efficient catalyst for pollutant degradation. However, thermodynamic data as obtained using cyclic voltammetry cannot be used to make definitive predictions about the kinetics of contaminant dehalogenation. Reductive dehalogenation will be a function of altered electrochemical properties of the tetrapyrrole as well as rates of contaminant diffusion to the site of tetrapyrrole sorption.

  14. A study on electrode gels for skin conductance measurements.

    PubMed

    Tronstad, Christian; Johnsen, Gorm Krogh; Grimnes, Sverre; Martinsen, Ørjan G

    2010-10-01

    Low-frequency skin conductance is used within several clinical applications and is mainly sensitive to sweating and the moisture content of the stratum corneum, but also how electrodes introduce changes in the electrical properties. Four electrode gels were investigated with regard to sorption characteristics and electrical properties. Skin conductance time series were collected from 18 test subjects during relaxation, exercise and recovery, wearing different pairs of electrodes contralaterally on the hypothenar and the T9 dermatome. Pressure test was applied on the T9 electrodes. Impedance frequency sweeps were taken on the T9 electrodes the same day and the next, parameterized to the Cole model. ANOVA on the initial skin conductance level change, exercise response amplitude, recovery offset and pressure-induced changes revealed significant differences among gel types. The wetter gels caused a higher positive level change, a greater response amplitude, larger recovery offset and greater pressure-induced artifacts compared to the solid gels. Sweating on the T9 site led to negative skin conductance responses for the wetter gels. Correlations were found between the desorption measurements and the initial skin conductance level change (hypothenar: R = 0.988 T9: R = 0.901) RM-ANOVA on the Cole parameters revealed a significant decrease in R(s) of the most resistive gel. Clinical implications are discussed.

  15. Cell separation technique in dilectrophoretic chip with bulk electrode

    NASA Astrophysics Data System (ADS)

    Iliescu, Ciprian; Tay, Francis E. H.; Xu, Guolin; Yu, Liming

    2006-01-01

    This paper presents a new technique for separation of two cell populations in a dielectrophoretic chip with bulk silicon electrode. A characteristic of the dielectrophoretic chip is its "sandwich" structure: glass/silicon/glass that generates a unique definition of the microfluidic channel with conductive walls (silicon) and isolating floor and ceiling (glass). The structure confers the opportunity to use the electrodes not only to generate a gradient of the electric field but also to generate a gradient of velocity of the fluid inside the channel. This interesting combination gives rise to a new solution for dielectrophoretic separation of two cell populations. The separation method consists of four steps. First, the microchannel is field with the cells mixture. Second, the cells are trapped in different locations of the microfluidic channel, the cell population which exhibits positive dielectrophoresis is trapped in the area where the distance between the electrodes is the minimum whilst, the other population that exhibit negative dielectrophoresis is trapped where the distance between electrodes is the maximum. In the next step, increasing the flow in the microchannel will result in an increased hydrodynamic force that sweeps the cells trapped by positive dielectrophoresis out of the chip. In the last step, the electric field is removed and the second population is sweep out and collected at the outlet. The device was tested for separation of dead yeast cells from live yeast cells. The paper presents analytical aspects of the separation method a comparative study between different electrode profiles and experimental results.

  16. Electrodes for solid state gas sensor

    DOEpatents

    Mukundan, Rangachary; Brosha, Eric L.; Garzon, Fernando

    2007-05-08

    A mixed potential electrochemical sensor for the detection of gases has a ceria-based electrolyte with a surface for exposing to the gases to be detected, and with a reference wire electrode and a sensing wire electrode extending through the surface and fixed within the electrolyte as the electrolyte is compressed and sintered. The electrochemical sensor is formed by placing a wire reference electrode and a wire sensing electrode in a die, where each electrode has a first compressed planar section and a second section depending from the first section with the second section of each electrode extending axially within the die. The die is filled with an oxide-electrolyte powder and the powder is pressed within the die with the wire electrodes. The wire-electrodes and the pressed oxide-electrolyte powder are sintered to form a ceramic electrolyte base with a reference wire electrode and a sensing wire electrode depending therefrom.

  17. Electrodes for solid state gas sensor

    DOEpatents

    Mukundan, Rangachary; Brosha, Eric L.; Garzon, Fernando

    2003-08-12

    A mixed potential electrochemical sensor for the detection of gases has a ceria-based electrolyte with a surface for exposing to the gases to be detected, and with a reference wire electrode and a sensing wire electrode extending through the surface and fixed within the electrolyte as the electrolyte is compressed and sintered. The electrochemical sensor is formed by placing a wire reference electrode and a wire sensing electrode in a die, where each electrode has a first compressed planar section and a second section depending from the first section with the second section of each electrode extending axially within the die. The die is filled with an oxide-electrolyte powder and the powder is pressed within the die with the wire electrodes. The wire-electrodes and the pressed oxide-electrolyte powder are sintered to form a ceramic electrolyte base with a reference wire electrode and a sensing wire electrode depending therefrom.

  18. Implanted electrodes for multi-month EEG.

    PubMed

    Jochum, Thomas; Engdahl, Susannah; Kolls, Brad J; Wolf, Patrick

    2014-01-01

    An implanted electroencephalogram (EEG) recorder would help diagnose infrequent seizure-like events. A proof-of-concept study quantified the electrical characteristics of the electrodes planned for the proposed recorder. The electrodes were implanted in an ovine model for eight weeks. Electrode impedance was less than 800 Ohms throughout the study. A frequency-domain determination of sedation performed similarly for surface versus implanted electrodes throughout the study. The time-domain correlation between an implanted electrode and a surface electrode was almost as high as between two surface electrodes (0.86 versus 0.92). EEG-certified clinicians judged that the implanted electrode quality was adequate to excellent and that the implanted electrodes provided the same clinical information as surface electrodes except for a noticeable amplitude difference. No significant issues were found that would stop development of the EEG recorder.

  19. Magnetic field effects on the open circuit potential of ferromagnetic electrodes in corroding solutions.

    PubMed

    Dass, Amala; Counsil, Joseph A; Gao, Xuerong; Leventis, Nicholas

    2005-06-02

    Magnetic fields shift the open circuit potential (OCP) of ferromagnetic electrodes (Fe, Co, and Ni) in corroding solutions. The OCP changes we observe (a) follow the series Fe>Co>Ni; (b) increase with the magnetic flux density; (c) reach a maximum with disk electrodes approximately 1 mm in diameter; and (d) depend on the orientation of the electrode. We report that when the surface of the electrode is oriented parallel (theta = 90 degrees) or perpendicular (theta = 0 degrees) to the magnetic field, the open circuit potential moves in opposite directions (positive and negative, respectively) with the largest changes occurring when the electrode surface is parallel to the magnetic field. Nonconvective sleeve electrodes produce the same behavior. The overall experimental evidence suggests that the magnetic field changes the OCP by modifying the surface concentrations of the paramagnetic participants in the corrosion process of the ferromagnetic electrode by species in solution; this in turn is accomplished by imposing a field-gradient driven mode of mass transfer upon paramagnetic species in solution (magnetophoresis). Simulations of the magnetic field around the ferromagnetic electrode at the two extreme orientations considered here show that in one case (theta = 90 degrees) field gradients actually repel, while in the other case (theta = 0 degrees) they attract paramagnetic species in the vicinity of the electrode.

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

    SciTech Connect

    Pezeshki, Alan M.; Sacci, Robert L.; Veith, Gabriel M.; Zawodzinski, Thomas A.; Mench, Matthew 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 electrode 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.

  1. Extraction electrode geometry for a calutron

    DOEpatents

    Veach, A.M.; Bell, W.A. Jr.

    1975-09-23

    This patent relates to an improved geometry for the extraction electrode and the ground electrode utilized in the operation of a calutron. The improved electrodes are constructed in a partial-picture-frame fashion with the slits of both electrodes formed by two tungsten elongated rods. Additional parallel spaced-apart rods in each electrode are used to establish equipotential surfaces over the rest of the front of the ion source. (auth)

  2. Porous silicon as a neural electrode material.

    PubMed

    Persson, Jörgen; Danielsen, Nils; Wallman, Lars

    2007-01-01

    The electrical properties of the solid state/fluid (Ringer solution) interface for phosphorous- and boron-doped porous silicon are reported and the benefits of using porous silicon as neural recording electrodes are discussed. The impedance, reactance and resistance for doped porous and planar silicon, in Ringer solution, were compared to gold electrodes. Planar silicon displayed approximately a three times higher reactance than porous electrodes. The phosphorous-doped porous electrodes displayed a similar reactance compared to the gold electrodes.

  3. Considerations for a high-performance thermionic energy conversion device based on a negative electron affinity emitter

    NASA Astrophysics Data System (ADS)

    Smith, Joshua Ryan; Bilbro, Griff L.; Nemanich, Robert J.

    2007-12-01

    A theory is developed to model the effect a negative electron affinity (NEA) emitter electrode has on the negative space charge effect of a vacuum thermionic energy conversion device (TEC). The theory is derived by treating the electrons in the interelectrode space as a collisionless gas and self-consistently solving the Boltzmann transport equation and Poisson equation. The theory determines the point on the voltage-current characteristic such that the maximum motive due to space charge is at the same level as the conduction band minimum. It is shown that emitter electrodes with an NEA significantly mitigate the negative space charge effect; therefore a TEC employing such an electrode will outperfrom a similar TEC with conventional electrodes in terms of output power. Additionally, it is shown that a TEC with an NEA emitter electrode can have a greater interelectrode spacing than a TEC with conventional electrodes operating under similar conditions where the outputs of both TEC’s are comparable.

  4. Optically transparent multi-suction electrode arrays

    PubMed Central

    Nagarah, John M.; Stowasser, Annette; Parker, Rell L.; Asari, Hiroki; Wagenaar, Daniel A.

    2015-01-01

    Multielectrode arrays (MEAs) allow for acquisition of multisite electrophysiological activity with submillisecond temporal resolution from neural preparations. The signal to noise ratio from such arrays has recently been improved by substrate perforations that allow negative pressure to be applied to the tissue; however, such arrays are not optically transparent, limiting their potential to be combined with optical-based technologies. We present here multi-suction electrode arrays (MSEAs) in quartz that yield a substantial increase in the detected number of units and in signal to noise ratio from mouse cortico-hippocampal slices and mouse retina explants. This enables the visualization of stronger cross correlations between the firing rates of the various sources. Additionally, the MSEA's transparency allows us to record voltage sensitive dye activity from a leech ganglion with single neuron resolution using widefield microscopy simultaneously with the electrode array recordings. The combination of enhanced electrical signals and compatibility with optical-based technologies should make the MSEA a valuable tool for investigating neuronal circuits. PMID:26539078

  5. Conductive lithium storage electrode

    DOEpatents

    Chiang, Yet-Ming [Framingham, MA; Chung, Sung-Yoon [Incheon, KR; Bloking, Jason T [Mountain View, CA; Andersson, Anna M [Vasteras, SE

    2012-04-03

    A compound comprising a composition A.sub.x(M'.sub.1-aM''.sub.a).sub.y(XD.sub.4).sub.z, A.sub.x(M'.sub.1-aM''.sub.a).sub.y(DXD.sub.4).sub.z, or A.sub.x(M'.sub.1-aM''.sub.a).sub.y(X.sub.2D.sub.7).sub.z, and have values such that x, plus y(1-a) times a formal valence or valences of M', plus ya times a formal valence or valence of M'', is equal to z times a formal valence of the XD.sub.4, X.sub.2D.sub.7, or DXD.sub.4 group; or a compound comprising a composition (A.sub.1-aM''.sub.a).sub.xM'.sub.y(XD.sub.4).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(DXD.sub.4).sub.z (A.sub.1-aM''.sub.a).sub.xM'.sub.y(X.sub.2D.sub.7).sub.z and have values such that (1-a).sub.x plus the quantity ax times the formal valence or valences of M'' plus y times the formal valence or valences of M' is equal to z times the formal valence of the XD.sub.4, X.sub.2D.sub.7 or DXD.sub.4 group. In the compound, A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen, 0.0001electrodes and storage batteries and can have a gravimetric capacity of at least about 80 mAh/g while being charged/discharged at greater than about C rate of the compound.

  6. Conductive lithium storage electrode

    DOEpatents

    Chiang, Yet-Ming [Framingham, MA; Chung, Sung-Yoon [Seoul, KR; Bloking, Jason T [Cambridge, MA; Andersson, Anna M [Uppsala, SE

    2008-03-18

    A compound comprising a composition A.sub.x(M'.sub.1-aM''.sub.a).sub.y(XD.sub.4).sub.z, A.sub.x(M'.sub.1-aM''.sub.a).sub.y(DXD.sub.4).sub.z, or A.sub.x(M'.sub.1-aM''.sub.a).sub.y(X.sub.2D.sub.7).sub.z, and have values such that x, plus y(1-a) times a formal valence or valences of M', plus ya times a formal valence or valence of M'', is equal to z times a formal valence of the XD.sub.4, X.sub.2D.sub.7, or DXD.sub.4 group; or a compound comprising a composition (A.sub.1-aM''.sub.a).sub.xM'.sub.y(XD.sub.4).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(DXD.sub.4).sub.z(A.sub.1-aM''.sub.a).s- ub.xM'.sub.y(X.sub.2D.sub.7).sub.z and have values such that (1-a).sub.x plus the quantity ax times the formal valence or valences of M'' plus y times the formal valence or valences of M' is equal to z times the formal valence of the XD.sub.4, X.sub.2D.sub.7 or DXD.sub.4 group. In the compound, A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen, 0.0001electrodes and storage batteries and can have a gravimetric capacity of at least about 80 mAh/g while being charged/discharged at greater than about C rate of the compound.

  7. Patternable Solvent-Processed Thermoplastic Graphite Electrodes.

    PubMed

    Klunder, Kevin J; Nilsson, Zach; Sambur, Justin B; Henry, Charles S

    2017-09-13

    Since their invention in the 1950s, composite carbon electrodes have been employed in a wide variety of applications, ranging from batteries and fuel cells to chemical sensors, because they are easy to make and pattern at millimeter scales. Despite their widespread use, traditional carbon composite electrodes have substandard electrochemistry relative to metallic and glassy carbon electrodes. As a result, there is a critical need for new composite carbon electrodes that are highly electrochemically active, have universal and easy fabrication into complex geometries, are highly conductive, and are low cost. Herein, a new solvent-based method is presented for making low-cost composite graphite electrodes containing a thermoplastic binder. The electrodes, which are termed thermoplastic electrodes (TPEs), are easy to fabricate and pattern, give excellent electrochemical performance, and have high conductivity (700 S m(-1)). The thermoplastic binder enables the electrodes to be hot embossed, molded, templated, and/or cut with a CO2 laser into a variety of intricate patterns. Crucially, these electrodes show a marked improvement in peak current, peak separation, and resistance to charge transfer over traditional carbon electrodes. The impact of electrode composition, surface treatment (sanding, polishing, plasma treatment), and graphite source were found to significantly impact fabrication, patterning, conductivity, and electrochemical performance. Under optimized conditions, electrodes generated responses similar to more expensive and difficult to fabricate graphene and highly oriented pyrolytic graphite electrodes. The TPE electrode system reported here provides a new approach for fabricating high performance carbon electrodes with utility in applications ranging from sensing to batteries.

  8. Detection of chlorinated quinones using interdigitated electrodes coupled with capillary electrophoresis.

    PubMed

    Male, Keith B; Luong, John H T

    2003-03-01

    An array of eight interdigitated microband gold electrodes (IDEs) has been developed together with electrophoretic separation for analysis of chlorinated hydroquinones (ClHQs) and benzoquinones (ClBQs). The IDE chip positioned very close to the separation capillary outlet served as an amplification/detection system without the requirement for frequent "capillary-electrode" alignment. ClHQs, electrophoretically migrating to the IDE surface, were oxidized at +1.1 V by seven electrodes of the array and then detected by the remaining electrode, poised at -0.1 V. Conversely, ClBQs were detected at +1.1 V by the detecting electrode after having been reduced at the 7 adjacent electrodes poised at -0.1 V. There was an amplification effect on both the detecting electrode as well as the adjacent electrodes because of the recycle between ClHQs and ClBQs. The detecting "amplification" current response was dependent on the potentials applied, the position of the detecting electrode on the array, the number of adjacent electrodes being used for recycling and the distance between the oxidative and reductive electrodes. Micellar electrokinetic chromatography (MEKC) separation of the analytes was achieved using 30 mM sodium dodecyl sulfate (SDS) with a detection limit in the range of 2-20 micro M. In addition to a facile "capillary-electrode" alignment, the important aspect described here was the capability of detecting through recycling a reduced compound (in the case of ClHQs) at a negative potential to circumvent fouling and electroactive interferences. An appealing feature was also the concurrent oxidation/reduction detection for each compound to ascertain peak assignment, as interfering compounds are less likely to exhibit the same oxidative/reductive characteristics and electrophoretic mobilities as the target analytes.

  9. Raman spectroelectrochemical study of electrochemical decomposition of poly(neutral red) at a gold electrode.

    PubMed

    Mazeikiene, R; Niaura, G; Malinauskas, A

    2009-08-01

    A gold electrode, modified with poly(neutral red), has been studied with surface-enhanced resonance Raman spectroscopy at 676.4 nm excitation. It has been shown that both qualitative and quantitative changes in Raman spectra occur during prolonged holding of the modified electrode in pH 7.0 solution at a controlled electrode potential ranging from -0.6 to -0.2V vs. Ag/AgCl, indicating that a decomposition of the poly(neutral red) layer proceeds. The decomposition proceeds slower at a more negative electrode potential. From kinetic data obtained, first-order decomposition rate constants have been calculated, ranging from 9.17x10(-4) to 1.09x10(-2) min(-1) for electrode potential ranging from -0.6 to -0.2 V.

  10. Fabrication and characterization of solid mercury amalgam electrodes for protein analysis.

    PubMed

    Jusková, Petra; Ostatná, Veronika; Palecek, Emil; Foret, Frantisek

    2010-04-01

    Gold and carbon electrodes have been largely used as transducers in protein and DNA sensors and arrays. Liquid mercury electrodes, with potential windows allowing detection of DNA and protein reduction processes at highly negative potentials, were considered as useless in such arrays. Here, we show that solid amalgam electrode (SAE) arrays can be prepared as a substitution of liquid mercury in the analysis of the above biomacromolecules. Vacuum metal sputtering on a glass substrate, photolithography, and galvanic mercury amalgam formation were used for fabrication of an inexpensive disposable electrode array. The resulting ultrathin (less than 1 microm) amalgam microelectrodes were characterized with respect to influence of the electrode composition and size on the reproducibility and stability of electrochemical signals. Further characterization was performed using electron microscopy and the well-established ruthenium electrochemistry. Final, optimized, design was applied in protein analysis employing the recently described electrocatalytic chronopotentiometric peak H.

  11. [Electrocochleography using Transtympanic, Ear Drum and Ear Canal Electrode in Diagnosis of Morbus Menière].

    PubMed

    Tiefenbach, M; Shehata-Dieler, W; Cebulla, M

    2015-10-01

    Aim of this study was to explore the clinical value of non-invasive recordings of electrocochleography in comparison to the use of invasive electrodes for the diagnosis of endolymphatic hydrops in patients with suspicious Morbus Menière. 15 patients with clinical suspicion of Morbus Menière underwent electrocochleography with transtympanic needle-electrode as well as tympanic membrane electrode. 10 patients received electrocochleography with transtympanic needle-electrode and ear canal electrode. A control group of 12 healthy adults was evaluated using tympanic membrane electrode. The negative electrode was placed on the ipsilateral mastoid, the ground electrode in the middle of the forehead. For stimulation broadband click stimulus as well as long tone bursts of 1, 2 and 4 kHz were applied. In addition the impedance of the electrode was registered. While transtympanic electrocochleography gave reliable results in 100% of these cases, extratympanic recordings often manifested poor wave morphology. The electrocochleographic measures following stimulation with 1 and 2 kHz long tone bursts were the best measures to identify endolymphatic hydrops. This was the case with transtympanic as well as with tympanic membrane electrodes. There was no correlation between impedance and wave morphology. For the evaluation of Morbus Menière non-invasive electrocochleography showed good results using a tympanic canal electrode with 1 and 2 kHz tone bursts. Yet in unclear cases transtympanic electrocochleography should be preferred. © Georg Thieme Verlag KG Stuttgart · New York.

  12. Investigations of negative and positive cesium ion species

    NASA Technical Reports Server (NTRS)

    Chanin, L. M.

    1978-01-01

    A direct test is provided of the hypothesis of negative ion creation at the anode or collector of a diode operating under conditions simulating a cesium thermionic converter. The experimental technique involves using direct ion sampling through the collector electrode with mass analysis using a quadrupole mass analyzer. Similar measurements are undertaken on positive ions extracted through the emitter electrode. Measurements were made on a variety of gases including pure cesium, helium-cesium mixtures and cesium-hydrogen as well as cesium-xenon mixtures. The gas additive was used primarily to aid in understanding the negative ion formation processes. Measurements were conducted using emitter (cathode) temperatures up to about 1000 F. The major negative ion identified through the collector was Cs(-) with minor negative ion peaks tentatively identified as H(-), H2(-), H3(-), He(-) and a mass 66. Positive ions detected were believed to be Cs(+), Cs2(+) and Cs3(+).

  13. Control of edge effects of oxidant electrode

    DOEpatents

    Carr, Peter; Chi, Chen H.

    1981-09-08

    Described is an electrode assembly comprising; a. a porous electrode having a first and second exterior face with a cavity formed in the interior between said exterior faces thereby having first and second interior faces positioned opposite the first and second exterior faces; b. a counter electrode positioned facing each of the first and second exterior faces of the porous electrode; c. means for passing an oxidant through said porous electrode; and d. screening means for blocking the interior face of the porous electrode a greater amount than the blocking of the respective exterior face of the porous electrode, thereby maintaining a differential of oxidant electrode surface between the interior face and the exterior face. The electrode assembly is useful in a metal, halogen, halogen hydrate electrical energy storage device.

  14. Porous-electrode preparation method

    DOEpatents

    Arons, R.M.; Dusek, J.T.

    1981-09-17

    A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity.

  15. Multiplexed DNA-modified electrodes.

    PubMed

    Slinker, Jason D; Muren, Natalie B; Gorodetsky, Alon A; Barton, Jacqueline K

    2010-03-03

    We report the use of silicon chips with 16 DNA-modified electrodes (DME chips) utilizing DNA-mediated charge transport for multiplexed detection of DNA and DNA-binding protein targets. Four DNA sequences were simultaneously distinguished on a single DME chip with 4-fold redundancy, including one incorporating a single base mismatch. These chips also enabled investigation of the sequence-specific activity of the restriction enzyme Alu1. DME chips supported dense DNA monolayer formation with high reproducibility, as confirmed by statistical comparison to commercially available rod electrodes. The working electrode areas on the chips were reduced to 10 microm in diameter, revealing microelectrode behavior that is beneficial for high sensitivity and rapid kinetic analysis. These results illustrate how DME chips facilitate sensitive and selective detection of DNA and DNA-binding protein targets in a robust and internally standardized multiplexed format.

  16. Multiplexed DNA-Modified Electrodes

    PubMed Central

    Slinker, Jason D.; Muren, Natalie B.; Gorodetsky, Alon A.; Barton, Jacqueline K.

    2011-01-01

    We report the use of silicon chips with 16 DNA-modified electrodes (DME chips) utilizing DNA-mediated charge transport for multiplexed detection of DNA and DNA-binding protein targets. Four DNA sequences were simultaneously distinguished on a single DME chip with fourfold redundancy, including one incorporating a single base mismatch. These chips also enabled investigation of the sequence-specific activity of the restriction enzyme Alu1. DME chips supported dense DNA monolayer formation with high reproducibility, as confirmed by statistical comparison to commercially available rod electrodes. The working electrode areas on the chips were reduced to 10 µm in diameter, revealing microelectrode behavior that is beneficial for high sensitivity and rapid kinetic analysis. These results illustrate how DME chips facilitate sensitive and selective detection of DNA and DNA-binding protein targets in a robust and internally standardized multiplexed format. PMID:20131780

  17. Composite Electrodes for Electrochemical Supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Jun; Yang, Quan Min; Zhitomirsky, Igor

    2010-03-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4-6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7-15 mg cm-2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g-1 was obtained at a scan rate of 2 mV s-1 for mass loading of 7 mg cm-2. The SC decreased with increasing scan rate and increasing electrode mass.

  18. Neural stimulation and recording electrodes.

    PubMed

    Cogan, Stuart F

    2008-01-01

    Electrical stimulation of nerve tissue and recording of neural electrical activity are the basis of emerging prostheses and treatments for spinal cord injury, stroke, sensory deficits, and neurological disorders. An understanding of the electrochemical mechanisms underlying the behavior of neural stimulation and recording electrodes is important for the development of chronically implanted devices, particularly those employing large numbers of microelectrodes. For stimulation, materials that support charge injection by capacitive and faradaic mechanisms are available. These include titanium nitride, platinum, and iridium oxide, each with certain advantages and limitations. The use of charge-balanced waveforms and maximum electrochemical potential excursions as criteria for reversible charge injection with these electrode materials are described and critiqued. Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.

  19. Silver-silver sulfate reference electrodes for use in lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Ruetschi, Paul

    Electrochemical properties of silver-silver sulfate reference electrodes for lead-acid batteries are described, and the following possible applications discussed: Determination of individual capacities of positive and negative plates. Monitoring individual electrode behavior during deep discharge and cell reversal. Optimization charge or discharge parameters, by controlling the current such that pre-determined limits of positive or negative half-cell potential are respected. Observation of acid concentration differences, for example due to acid stratification, by measuring diffusion potentials (concentration-cell voltages). Detection of defective cells, and defective plate sets, in a string of cells, at the end of their service life. Silver-silver sulfate reference electrodes, permanently installed in lead-acid cells, may be a means to improve battery management, and therewith to improve reliability and service life. In vented batteries, reference electrodes may be used to limit positive plate polarization during charge, or float-charge. Limiting the positive half-cell potential to an upper, pre-set value would permit to keep anodic corrosion as low as possible. During cycling, discharge could be terminated when the half-cell potential of the positive electrode has dropped to a pre-set limit. This would prevent excessive discharge of the positive electrodes, which could result in an improvement of cycle life. In valve-regulated batteries, reference electrodes may be used to adjust float-charge conditions such as to assure sufficient cathodic polarization of the negative electrodes, in order to avoid sulfation. The use of such reference electrodes could be beneficial particularly in multi-cell batteries, with overall voltages above 12 V, operated in a partial-state-of-charge.

  20. Nanofiber membrane-electrode-assembly and method of fabricating same

    SciTech Connect

    Pintauro, Peter N.; Ballengee, Jason; Brodt, Matthew

    2016-02-02

    In one aspect of the present invention, a fuel cell membrane-electrode-assembly (MEA) has an anode electrode, a cathode electrode, and a membrane disposed between the anode electrode and the cathode electrode. At least one of the anode electrode, the cathode electrode and the membrane is formed of electrospun nanofibers.

  1. Quasi-Monopolar Stimulation: A Novel Electrode Design Configuration for Performance Optimization of a Retinal Neuroprosthesis

    PubMed Central

    Khalili Moghadam, Gita; Wilke, Robert; Suaning, Gregg J.; Lovell, Nigel H.; Dokos, Socrates

    2013-01-01

    In retinal neuroprostheses, spatial interaction between electric fields from various electrodes – electric crosstalk – may occur in multielectrode arrays during simultaneous stimulation of the retina. Depending on the electrode design and placement, this crosstalk can either enhance or degrade the functional characteristics of a visual prosthesis. To optimize the device performance, a balance must be satisfied between the constructive interference of crosstalk on dynamic range and power consumption and its negative effect on artificial visual acuity. In the present computational modeling study, we have examined the trade-off in these positive and negative effects using a range of currently available electrode array configurations, compared to a recently proposed stimulation strategy – the quasi monopolar (QMP) configuration – in which the return current is shared between local bipolar guards and a distant monopolar electrode. We evaluate the performance of the QMP configuration with respect to the implantation site and electrode geometry parameters. Our simulation results demonstrate that the beneficial effects of QMP are only significant at electrode-to-cell distances greater than the electrode dimensions. Possessing a relatively lower activation threshold, QMP was found to be superior to the bipolar configuration in terms of providing a relatively higher visual acuity. However, the threshold for QMP was more sensitive to the topological location of the electrode in the array, which may need to be considered when programming the manner in which electrode are simultaneously activated. This drawback can be offset with a wider dynamic range and lower power consumption of QMP. Furthermore, the ratio of monopolar return current to total return can be used to adjust the functional performance of QMP for a given implantation site and electrode parameters. We conclude that the QMP configuration can be used to improve visual information-to-stimulation mapping in a

  2. Dielectrophoretic Manipulation and Separation of Microparticles Using Microarray Dot Electrodes

    PubMed Central

    Yafouz, Bashar; Kadri, Nahrizul Adib; Ibrahim, Fatimah

    2014-01-01

    This paper introduces a dielectrophoretic system for the manipulation and separation of microparticles. The system is composed of five layers and utilizes microarray dot electrodes. We validated our system by conducting size-dependent manipulation and separation experiments on 1, 5 and 15 μm polystyrene particles. Our findings confirm the capability of the proposed device to rapidly and efficiently manipulate and separate microparticles of various dimensions, utilizing positive and negative dielectrophoresis (DEP) effects. Larger size particles were repelled and concentrated in the center of the dot by negative DEP, while the smaller sizes were attracted and collected by the edge of the dot by positive DEP. PMID:24705632

  3. Electrodes for Semiconductor Gas Sensors

    PubMed Central

    Lee, Sung Pil

    2017-01-01

    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. PMID:28346349

  4. Ceramic component for MHD electrode

    DOEpatents

    Marchant, David D.; Bates, Junior L.

    1981-01-01

    A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hf.sub.x In.sub.y A.sub.z O.sub.2 where x=0.1 to 0.4, y=0.3 to 0.6, z=0.1 to 0.4 and A is a lanthanide rare earth or yttrium. The component is suitable for use in the fabrication of MHD electrodes or as the current leadout portion of a composite electrode with other ceramic components.

  5. Ceramic components for MHD electrode

    DOEpatents

    Marchant, D.D.

    A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hf/sub x/In/sub y/A/sub z/O/sub 2/ where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a lanthanide rare earth or yttrium. The component is suitable for use in the fabrication of MHD electrodes or as the current leadout portion of a composite electrode with other ceramic components.

  6. Nanoengineered membrane electrode assembly interface

    DOEpatents

    Song, Yujiang; Shelnutt, John A

    2013-08-06

    A membrane electrode structure suitable for use in a membrane electrode assembly (MEA) that comprises membrane-affixed metal nanoparticles whose formation is controlled by a photochemical process that controls deposition of the metal nanoparticles using a photocatalyst integrated with a polymer electrolyte membrane, such as an ionomer membrane. Impregnation of the polymer membrane with the photocatalyst prior to metal deposition greatly reduces the required amount of metal precursor in the deposition reaction solution by restricting metal reduction substantially to the formation of metal nanoparticles affixed on or near the surface of the polymer membrane with minimal formation of metallic particles not directly associated with the membrane.

  7. Method for manufacturing magnetohydrodynamic electrodes

    DOEpatents

    Killpatrick, D.H.; Thresh, H.R.

    1980-06-24

    A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator is described comprising the steps of preparing a billet having a core of a first metal, a tubular sleeve of a second metal, and an outer sheath of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MHD channel frame. The method forms a bond between the first metal of the core and the second metal of the sleeve strong enough to withstand a hot and corrosive environment.

  8. Reference electrode for electrolytic cell

    DOEpatents

    Kessie, R.W.

    1988-07-28

    A reference electrode device is provided for a high temperature electrolytic cell used to electrolytically recover uranium from spent reactor fuel dissolved in an anode pool, the device having a glass tube to enclose the electrode and electrolyte and serve as a conductive membrane with the cell electrolyte, and an outer metal tube about the glass tube to serve as a shield and basket for any glass sections broken by handling of the tube to prevent their contact with the anode pool, the metal tube having perforations to provide access between the bulk of the cell electrolyte and glass membrane. 4 figs.

  9. Conducting polyaniline nanowire electrode junction

    NASA Astrophysics Data System (ADS)

    Gaikwad, Sumedh; Bodkhe, Gajanan; Deshmukh, Megha; Patil, Harshada; Rushi, Arti; Shirsat, Mahendra D.; Koinkar, Pankaj; Kim, Yun-Hae; Mulchandani, Ashok

    2015-03-01

    In this paper, a synthesis of conducting polyaniline nanowires electrode junction (CPNEJ) has been reported. Conducting polyaniline nanowires electrode junction on Si/SiO2 substrate (having 3 μm gap between two gold microelectrodes) is prepared. Polyaniline nanowires with diameter (ca. 140 nm to 160 nm) were synthesized by one step electrochemical polymerization using galvanostatic (constant current) technique to bridge this gap. The surface morphology of CPNEJ was studied by scanning electron microscope (SEM). The synthesized CPNEJ is an excellent platform for biosensor applications.

  10. Production method of nickel electrode

    NASA Technical Reports Server (NTRS)

    Ikeda, H.; Ohira, T.

    1982-01-01

    A nickel electrode having improved charging efficiency, an increased coefficient of discharging utilization, and large capacity is disclosed. Nickel hydroxide or nickel oxide is retained in a porous nickel substrate which is immersed in an aqueous solution of cobalt acetate with a pH 4.0 to 6.8. The electrode thus obtained is then immersed in an alkaline solution or heated to change cobalt acetate into cobalt hydroxide or cobalt oxide whereby the surface of nickel active material is covered with cobalt crystals and alloying of cobalt and nickel is promoted at the same time.

  11. Electrolytic cell with reference electrode

    DOEpatents

    Kessie, Robert W.

    1989-01-01

    A reference electrode device is provided for a high temperature electrolytic cell used to electrolytically recover uranium from spent reactor fuel dissolved in an anode pool, the device having a glass tube to enclose the electrode and electrolyte and serve as a conductive membrane with the cell electrolyte, and an outer metal tube about the glass tube to serve as a shield and basket for any glass sections broken by handling of the tube to prevent their contact with the anode pool, the metal tube having perforations to provide access between the bulk of the cell electrolyte and glass membrane.

  12. Protected electrode structures and methods

    DOEpatents

    Mikhaylik, Yuriy V.; Laramie, Michael G.; Kopera, John Joseph Christopher

    2017-08-08

    An electrode structure and its method of manufacture are disclosed. The disclosed electrode structures may be manufactured by depositing a first release layer on a first carrier substrate. A first protective layer may be deposited on a surface of the first release layer and a first electroactive material layer may then be deposited on the first protective layer. The first release layer may have a low mean peak to valley surface roughness, which may enable the formation of a thin protective layer with a low mean peak to valley surface roughness.

  13. A CHAT with Dan Johnson

    NASA Astrophysics Data System (ADS)

    Bertrand, Robert A.

    2003-04-01

    Dan's preoccupation with preventing NIHL is well known. For those of us who had the occasion to CHAT with him, we often heard him say ``if ears would bleed when exposed to noise, people would pay more attention to the harmful effect of noise upon hearing.'' His objective, as he often stated, was to eradicate NIHL so that in a few decades, it would become a historical footnote. Among his many preoccupations in his illustrious career, approaches and techniques to prevent NIHL were of primordial importance. One approach he advocated is the use of TTS instead of the STS in HCP's. His intention was to use the identification of TTS as an easy approach to introduce appropriate measures to prevent NIHL at a stage of reversibility rather than waiting for a confirmed permanent hearing loss, as noted with a confirmed STS. One of his last projects was developing the CHAT (Change of Hearing Audio Test) for easy use both in industrial and environmental settings to identify subjects with a TTS. Several groups are interested in pursuing his aim of using the TTS in HCP's, hoping to fulfill his comment that in a few decades, NIHL will become a historical footnote.

  14. Electrochemical reduction of an anion for ionic-liquid molecules on a lithium electrode studied by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Ando, Yasunobu; Kawamura, Yoshiumi; Ikeshoji, Tamio; Otani, Minoru

    2014-09-01

    We report ab initio molecular dynamics studies with electric field that reveal chemical stability of room temperature ionic liquid for charge transfer from lithium and nickel electrodes. Bis(trifluoromethanesulfonyl)imide (TFSI) is oxidized on the nickel electrode under a high positive bias condition as expected. However, TFSI is reduced on the lithium electrode under both positive and negative bias conditions, because the lithium electrode acts as a strong reductant. The decomposition of TFSI anion might induce the formation of LiF as a solid electrolyte interphase, which could restrain the TFSI reduction. The stability of an cation under reductant conditions is presented.

  15. The development of insulated electrocardiogram electrodes

    NASA Technical Reports Server (NTRS)

    Portnoy, W. M.; David, R. M.

    1971-01-01

    An integrated system was developed, consisting of an insulated electrode and an impedance transformer, which can be used for the acquisition of electrocardiographic data. The electrode consists of a thin layer of dielectric material deposited onto a silicon substrate. The impedance transformer is an operational amplifier used in the unity gain configuration. Both electrode and impedance transformer are contained in a plastic housing identical to that used with the NASA Apollo-type electrode. The lower cut off frequency of the electrode system is between 0.01 and 1.0 Hz, depending on the dielectric used and its thickness. Clinical quality electrocardiograms were obtained with these electrodes.

  16. Electrode assembly for a fluidized bed apparatus

    DOEpatents

    Schora, Jr., Frank C.; Matthews, Charles W.; Knowlton, Ted M.

    1976-11-23

    An electrode assembly comprising a high voltage electrode having a generally cylindrical shape and being electrically connected to a high voltage source, where the cylinder walls may be open to flow of fluids and solids; an electrically grounded support electrode supporting said high voltage electrode by an electrically insulating support where both of the electrically grounded and electrically insulating support may be hollow; and an electrically grounded liner electrode arranged concentrically around both the high voltage and support electrodes. This assembly is specifically adapted for use in a fluidized bed chemical reactor as an improved heating means therefor.

  17. Dan Johnson's impact on hearing research

    NASA Astrophysics Data System (ADS)

    Shotland, Lawrence I.

    2003-04-01

    Daniel L. Johnson is well known for his many technical contributions to noise research. Throughout a long and distinguished career at Wright-Patterson Air Force Base, Dan published the results of several significant experiments, including his landmark experiments on asymptotic threshold shift and exposure to impulse noise. His work in the area of noise exposure laid much of the groundwork for a greater understanding of the physiologic response to hazardous noise, much of which has since been incorporated in national and international standards. Dan is highly regarded for his tireless work on technical and advisory committees in noise, and most recently, ototoxicity. Throughout his career, Dan has adhered to a self-imposed standard of intellectual honesty and discovery. Dan's most recent endeavor, the development of a personal noise dosimeter designed for self-monitoring by the employee, is characteristic of his creativity and energy. Perhaps less well known are his contributions over the years to the success of his younger colleagues. He has accomplished this in an unselfish and egalitarian manner, oftentimes challenging and even contradicting his own research. The focus of this talk will elaborate on these facets of Dan's professional contributions.

  18. The effect of electrode temperature on the sparking voltage of short spark gaps

    NASA Technical Reports Server (NTRS)

    Silsbee, F B

    1924-01-01

    This report presents the results of an investigation to determine what effect the temperature of spark plug electrodes might have on the voltage at which a spark occurred. A spark gap was set up so that one electrode could be heated to temperatures up to 700 degrees C., while the other electrode and the air in the gap were maintained at room temperature. The sparking voltages were measured both with direct voltage and with voltage impulse from ignition coil. It was found that the sparking voltage of the gap decreased materially with increase of temperature. This change was more marked when the hot electrode was of negative polarity. The phenomena observed can be explained by the ionic theory of gaseous conduction, and serve to account for certain hitherto unexplained actions in the operation of internal combustion engines. These results indicate that the ignition spark will pass more readily when the spark-plug design is such as to make the electrodes run hot. This possible gain is, however, very closely limited by the danger of producing preignition. These experiments also show that sparking is somewhat easier when the hot electrode (which is almost always the central electrode) is negative than when the polarity is reversed.

  19. Corrosion resistant positive electrode for high-temperature, secondary electrochemical cell

    DOEpatents

    Otto, Neil C.; Warner, Barry T.; Smaga, John A.; Battles, James E.

    1983-01-01

    The corrosion rate of low carbon steel within a positive electrode of a high-temperature, secondary electrochemical cell that includes FeS as active material is substantially reduced by incorporating therein finely divided iron powder in stoichiometric excess to the amount required to form FeS in the fully charged electrode. The cell typically includes an alkali metal or alkaline earth metal as negative electrode active material and a molten metal halide salt as electrolyte. The excess iron permits use of inexpensive carbon steel alloys that are substantially free of the costly corrosion resistant elements chromium, nickel and molybdenum while avoiding shorten cell life resulting from high corrosion rates.

  20. Corrosion resistant positive electrode for high-temperature, secondary electrochemical cell

    DOEpatents

    Otto, N.C.; Warner, B.T.; Smaga, J.A.; Battles, J.E.

    1982-07-07

    The corrosion rate of low carbon steel within a positive electrode of a high-temperature, secondary electrochemical cell that includes FeS as active material is substantially reduced by incorporating therein finely divided iron powder in stoichiometric excess to the amount required to form FeS in the fully charged electrode. The cell typically includes an alkali metal or alkaline earth metal as negative electrode active material and a molten metal halide salt as electrolyte. The excess iron permits use of inexpensive carbon steel alloys that are substantially free of the costly corrosion resistant elements chromium, nickel and molybdenum while avoiding shorten cell life resulting from high corrosion rates.

  1. 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.

  2. IR Near-Field Study of the Solid Electrolyte Interphase on a Tin Electrode.

    PubMed

    Ayache, Maurice; Lux, Simon Franz; Kostecki, Robert

    2015-04-02

    There has been a dearth of suitable techniques for studying the chemical composition of solid electrolyte interphase (SEI) on Li-ion negative electrodes at a resolution of its basic building blocks' length scale. Infrared apertureless near-field scanning optical microscopy (IR aNSOM) is an emerging tool in the chemical characterization of interfacial layers on the nanometer scale. This work demonstrates an IR aNSOM imaging of the SEI layer on a model Sn electrode. IR aNSOM images reveal significant chemical contrast variations tied to specific topographic features and possible corresponding distribution of lithium carbonate and lithium ethylene dicarbonate on the Sn electrode surface.

  3. Influence of Electric Fields on Biofouling of Carbonaceous Electrodes.

    PubMed

    Pandit, Soumya; Shanbhag, Sneha; Mauter, Meagan; Oren, Yoram; Herzberg, Moshe

    2017-09-05

    Biofouling commonly occurs on carbonaceous capacitive deionization electrodes in the process of treating natural waters. Although previous work reported the effect of electric fields on bacterial mortality for a variety of medical and engineered applications, the effect of electrode surface properties and the magnitude and polarity of applied electric fields on biofilm development has not been comprehensively investigated. This paper studies the formation of a Pseudomonas aeruginosa biofilm on a Papyex graphite (PA) and a carbon aerogel (CA) in the presence and the absence of an electric field. The experiments were conducted using a two-electrode flow cell with a voltage window of ±0.9 V. The CA was less susceptible to biofilm formation compared to the PA due to its lower surface roughness, lower hydrophobicity, and significant antimicrobial properties. For both positive and negative applied potentials, we observed an inverse relationship between biofilm formation and the magnitude of the applied potential. The effect is particularly strong for the CA electrodes and may be a result of cumulative effects between material toxicity and the stress experienced by cells at high applied potentials. Under the applied potentials for both electrodes, high production of endogenous reactive oxygen species (ROS) was indicative of bacterial stress. For both electrodes, the elevated specific ROS activity was lowest for the open circuit potential condition, elevated when cathodically and anodically polarized, and highest for the ±0.9 V cases. These high applied potentials are believed to affect the redox potential across the cell membrane and disrupt redox homeostasis, thereby inhibiting bacterial growth.

  4. Culture-negative endocarditis

    MedlinePlus

    ... inflammation of the lining of one or more heart valves, but no endocarditis-causing germs can be found ... the heart, where they can settle on damaged heart valves. Alternative Names Endocarditis (culture-negative) Images Culture-negative ...

  5. A new method to induce molecular low bias negative differential resistance with multi-peaks

    NASA Astrophysics Data System (ADS)

    Min, Y.; Zhong, C. G.; Dong, Z. C.; Zhao, Z. Y.; Zhou, P. X.; Yao, K. L.

    2016-02-01

    According to a first-principles study of the transport properties of two thiolated anthracene-9,10-diono molecules sandwiching ethyl, a new method to induce molecular low bias negative differential resistance with multi-peaks for strong n- or p-type molecules is proposed. The anthracene-9,10-diono molecule shows strong n-type characteristics when in contact with Au and Ag electrodes via a thiolate. The multiple negative differential resistance effect originated from the molecule-electrode couple is different between Ag and Au electrodes. Our investigations may promise potential for applications in molecular devices with low power dissipation and multifunction in the future.

  6. [Negative symptoms: which antipsychotics?].

    PubMed

    Maurel, M; Belzeaux, R; Adida, M; Azorin, J-M

    2015-12-01

    Treating negative symptoms of schizophrenia is a major issue and a challenge for the functional and social prognosis of the disease, to which they are closely linked. First- and second-generation antipsychotics allow a reduction of all negative symptoms. The hope of acting directly on primary negative symptoms with any antipsychotic is not supported by the literature. However, the effectiveness of first- and second-generation antipsychotics is demonstrated on secondary negative symptoms. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  7. Negative ion generator

    DOEpatents

    Stinnett, Regan W.

    1984-01-01

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions.

  8. Negative ion generator

    DOEpatents

    Stinnett, R.W.

    1984-05-08

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions. 8 figs.

  9. Management of Cochlear Implant Electrode Migration.

    PubMed

    Rader, Tobias; Baumann, Uwe; Stöver, Timo; Weissgerber, Tobias; Adel, Youssef; Leinung, Martin; Helbig, Silke

    2016-10-01

    The present study reviewed a cochlear implant (CI) patient population after surgery, which received a free-fitting electrode carrier designed for hearing preservation. The aim was to determine the rate of electrode migration of the CI electrodes and present clinical and surgical implications. Retrospective patient review. Tertiary referral university hospital. Two hundred seventy-eight patients implanted uni- or bilaterally with lateral wall electrodes designed for hearing preservation (358 implants). The control group was 323 patients implanted uni- or bilaterally with preformed perimodiolar electrodes (468 implants). Determination of CI electrode migration was conducted according to a clinical test protocol. Revision surgery was offered in confirmed patients of electrode migration. A bone groove was considered to improve the fixation of the electrode. Audiological testing including speech audiometry, subjective sound quality rating, and bilateral pitch comparison in bilateral patients, as well as radiological examinations, were conducted. Electrode migration was observed solely in patients implanted with lateral wall electrodes; 10 of 358 patients with free-fitting electrodes (2.8%) had electrode migration, which was successfully confirmed by the proposed clinical test protocol. Nine of the 10 confirmed patients underwent reinsertion surgery. Mean perception score decreased from 75.0% to 62.1% after electrode migration and recovered completely after reinsertion surgery. A flowchart to detect electrode migration was designed for clinical practice. Although electrode migration is a rare complication in CI surgery, long-term follow-up diagnostics should include a test protocol to detect electrode shifts of lateral wall electrode arrays. A reinsertion surgery should be conducted in confirmed patients to recover speech perception.

  10. Rough Gold Electrodes for Decreasing Impedance at the Electrolyte/Electrode Interface.

    PubMed

    Koklu, Anil; Sabuncu, Ahmet C; Beskok, Ali

    2016-07-01

    Electrode polarization at the electrolyte/electrode interface is often undesirable for bio-sensing applications, where charge accumulated over an electrode at constant potential causes large potential drop at the interface and low measurement sensitivity. In this study, novel rough electrodes were developed for decreasing electrical impedance at the interface. The electrodes were fabricated using electrochemical deposition of gold and sintering of gold nanoparticles. The performances of the gold electrodes were compared with platinum black electrodes. A constant phase element model was used to describe the interfacial impedance. Hundred folds of decrease in interfacial impedance were observed for fractal gold electrodes and platinum black. Biotoxicity, contact angle, and surface morphology of the electrodes were investigated. Relatively low toxicity and hydrophilic nature of the fractal and granulated gold electrodes make them suitable for bioimpedance and cell electromanipulation studies compared to platinum black electrodes which are both hydrophobic and toxic.

  11. Rough Gold Electrodes for Decreasing Impedance at the Electrolyte/Electrode Interface

    PubMed Central

    Koklu, Anil; Sabuncu, Ahmet C.; Beskok, Ali

    2016-01-01

    Electrode polarization at the electrolyte/electrode interface is often undesirable for bio-sensing applications, where charge accumulated over an electrode at constant potential causes large potential drop at the interface and low measurement sensitivity. In this study, novel rough electrodes were developed for decreasing electrical impedance at the interface. The electrodes were fabricated using electrochemical deposition of gold and sintering of gold nanoparticles. The performances of the gold electrodes were compared with platinum black electrodes. A constant phase element model was used to describe the interfacial impedance. Hundred folds of decrease in interfacial impedance were observed for fractal gold electrodes and platinum black. Biotoxicity, contact angle, and surface morphology of the electrodes were investigated. Relatively low toxicity and hydrophilic nature of the fractal and granulated gold electrodes make them suitable for bioimpedance and cell electromanipulation studies compared to platinum black electrodes which are both hydrophobic and toxic. PMID:27695132

  12. Analysis of SOFCs Using Reference Electrodes

    SciTech Connect

    Finklea, H.; Chen, X.; Gerdes, K.; Pakalapati, S.; Celik, I.

    2013-01-01

    Reference electrodes are frequently applied to isolate the performance of one electrode in a solid oxide fuel cell. However, reference electrode simulations raise doubt to veracity of data collected using reference electrodes. The simulations predict that the reported performance for the one electrode will frequently contain performance of both electrodes. Nonetheless, recent reports persistently treat data so collected as ideally isolated. This work confirms the predictions of the reference electrode simulations on two SOFC designs, and to provides a method of validating the data measured in the 3-electrode configuration. Validation is based on the assumption that a change in gas composition to one electrode does not affect the impedance of the other electrode at open circuit voltage. This assumption is supported by a full physics simulation of the SOFC. Three configurations of reference electrode and cell design are experimentally examined using various gas flows and two temperatures. Impedance data are subjected to deconvolution analysis and equivalent circuit fitting and approximate polarization resistances of the cathode and anode are determined. The results demonstrate that the utility of reference electrodes is limited and often wholly inappropriate. Reported impedances and single electrode polarization values must be scrutinized on this basis.

  13. Sentential Negation in English

    ERIC Educational Resources Information Center

    Mowarin, Macaulay

    2009-01-01

    This paper undertakes a detailed analysis of sentential negation in the English language with Chomsky's Government-Binding theory of Transformational Grammar as theoretical model. It distinguishes between constituent and sentential negation in English. The essay identifies the exact position of Negation phrase in an English clause structure. It…

  14. Sentential Negation in English

    ERIC Educational Resources Information Center

    Mowarin, Macaulay

    2009-01-01

    This paper undertakes a detailed analysis of sentential negation in the English language with Chomsky's Government-Binding theory of Transformational Grammar as theoretical model. It distinguishes between constituent and sentential negation in English. The essay identifies the exact position of Negation phrase in an English clause structure. It…

  15. Selecting electrode configurations for image-guided cochlear implant programming using template matching

    NASA Astrophysics Data System (ADS)

    Zhang, Dongqing; Zhao, Yiyuan; Noble, Jack H.; Dawant, Benoit M.

    2017-03-01

    Cochlear implants (CIs) are used to treat patients with severe-to-profound hearing loss. In surgery, an electrode array is implanted in the cochlea. After implantation, the CI processor is programmed by an audiologist. One factor that negatively impacts outcomes and can be addressed by programming is cross-electrode neural stimulation overlap (NSO). In the recent past, we have proposed a system to assist the audiologist in programming the CI that we call Image-Guided CI Programming (IGCIP). IGCIP permits using CT images to detect NSO and recommend which subset of electrodes should be active to avoid NSO. In an ongoing clinical study, we have shown that IGCIP leads to significant improvement in hearing outcomes. Most of the IGCIP steps are robustly automated but electrode configuration selection still sometimes requires expert intervention. With expertise, Distance-Vs-Frequency (DVF) curves, which are a way to visualize the spatial relationship learned from CT between the electrodes and the nerves they stimulate, can be used to select the electrode configuration. In this work, we propose an automated technique for electrode configuration selection. It relies on matching new patients' DVF curves to a library of DVF curves for which electrode configurations are known. We compare this approach to one we have previously proposed. We show that, generally, our new method produces results that are as good as those obtained with our previous one while being generic and requiring fewer parameters.

  16. 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

  17. Negative Correlations in Visual Cortical Networks

    PubMed Central

    Chelaru, Mircea I.; Dragoi, Valentin

    2016-01-01

    The amount of information encoded by cortical circuits depends critically on the capacity of nearby neurons to exhibit trial-to-trial (noise) correlations in their responses. Depending on their sign and relationship to signal correlations, noise correlations can either increase or decrease the population code accuracy relative to uncorrelated neuronal firing. Whereas positive noise correlations have been extensively studied using experimental and theoretical tools, the functional role of negative correlations in cortical circuits has remained elusive. We addressed this issue by performing multiple-electrode recording in the superficial layers of the primary visual cortex (V1) of alert monkey. Despite the fact that positive noise correlations decayed exponentially with the difference in the orientation preference between cells, negative correlations were uniformly distributed across the population. Using a statistical model for Fisher Information estimation, we found that a mild increase in negative correlations causes a sharp increase in network accuracy even when mean correlations were held constant. To examine the variables controlling the strength of negative correlations, we implemented a recurrent spiking network model of V1. We found that increasing local inhibition and reducing excitation causes a decrease in the firing rates of neurons while increasing the negative noise correlations, which in turn increase the population signal-to-noise ratio and network accuracy. Altogether, these results contribute to our understanding of the neuronal mechanism involved in the generation of negative correlations and their beneficial impact on cortical circuit function. PMID:25217468

  18. A new dry biomedical electrode

    NASA Technical Reports Server (NTRS)

    Luce, R. S.; Cleveland, G. J.

    1973-01-01

    Electronic circuitry contains new operational amplifier which incorporates monolithic super-gain transistors. Electrode does not provide voltage amplification; instead, it acts as current amplifier to make it possible to pick up electrical potentials from surface of highly resistant dry skin.

  19. Multiple input electrode gap controller

    DOEpatents

    Hysinger, Christopher L.; Beaman, Joseph J.; Melgaard, David K.; Williamson, Rodney L.

    1999-01-01

    A method and apparatus for controlling vacuum arc remelting (VAR) furnaces by estimation of electrode gap based on a plurality of secondary estimates derived from furnace outputs. The estimation is preferably performed by Kalman filter. Adaptive gain techniques may be employed, as well as detection of process anomalies such as glows.

  20. Multiple input electrode gap controller

    DOEpatents

    Hysinger, C.L.; Beaman, J.J.; Melgaard, D.K.; Williamson, R.L.

    1999-07-27

    A method and apparatus for controlling vacuum arc remelting (VAR) furnaces by estimation of electrode gap based on a plurality of secondary estimates derived from furnace outputs. The estimation is preferably performed by Kalman filter. Adaptive gain techniques may be employed, as well as detection of process anomalies such as glows. 17 figs.