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Shimshon Gottesfeld

Other affiliations: Los Alamos National Laboratory
Bio: Shimshon Gottesfeld is an academic researcher from University of Delaware. The author has contributed to research in topics: Membrane & Anode. The author has an hindex of 52, co-authored 113 publications receiving 19813 citations. Previous affiliations of Shimshon Gottesfeld include Los Alamos National Laboratory.


Papers
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Journal ArticleDOI
TL;DR: On resout le probleme de l'empoisonnement du catalyseur platine par la presence de CO a 100 ppm dans le gaz d'alimentation par l'injection d'O 2 a 4,5% dans l'gaz de alimentation constitue d'hydrogene as discussed by the authors.
Abstract: On resout le probleme de l'empoisonnement du catalyseur platine par la presence de CO a 100 ppm dans le gaz d'alimentation par l'injection d'O 2 a 4,5% dans le gaz d'alimentation constitue d'hydrogene

358 citations

Journal ArticleDOI
TL;DR: In this paper, the diffusion coefficient and conductivity of each of these membranes were determined as functions of membrane water content and contact angle measurements indicated that the surface of a perfluorosulfonic acid membrane exposed to water vapor is quite hydrophobic, even in the presence of saturated water vapor.

355 citations

Journal ArticleDOI
TL;DR: In this article, the effect of variation of temperature on DMFC cathode potential was studied. But the authors focused on the long-term stability of the anode, and crossover of methanol.

278 citations

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TL;DR: McBreen et al. as mentioned in this paper showed that voltage losses associated with CO poisoning are significantly amplified with diluted hydrogen feed streams and particularly so under high fuel utilization, and made projections on improvements required, qualitative and quantitative, in the physical parameters of the anode catalyst surface chemistry to significantly improve CO tolerance.
Abstract: We describe a polymer electrolyte fuel cell model emphasizing operation on hydrocarbon reformate, i.e., the anode feed stream consists of dry H 2 concentrations as low as 40%, inlet CO levels of 10-100 ppm, and hydrogen fuel utilization as high as 90%. Refinements of interfacial kinetics equations used in our previous work on CO effects in H 2 anodes have yielded a better quantitative fit to the measured dependence of voltage loss on inlet CO level [in Electrode Materials and Processes for Energy Conversion and Storage, J. McBreen, S. Mukerjee, and S. Srinivasan, Editors, PV 97-13, pp. 15-24, The Electrochemical Society Proceedings Series, Pennington, NJ (1997)]. We calculate anode potential losses by coupling such interfacial kinetic processes to reactant diffusion limitations and ionic resistance in the catalyst layer, and by accounting for the drop in local hydrogen concentration along the flow channel due to significant fuel utilization. As a result of internal readjustment of cell overpotentials when hydrogen concentration drops along the flow channel, we show that loss of current, or power, under the realistic condition of constant cell voltage is smaller than loss of current at constant anode potential. We show that voltage losses associated with CO poisoning are significantly amplified with diluted hydrogen feed streams and particularly so under high fuel utilization. We make projections on improvements required, qualitative and quantitative, in the physical parameters of the anode catalyst surface chemistry to significantly improve CO tolerance.

269 citations

Journal ArticleDOI
TL;DR: In this paper, an in-situ probe of surface composition for a direct methanol fuel cell (DMFC) catalyst is presented, based on voltammetry of CO adsorbed at bulk PtRu alloy electrode surfaces.

267 citations


Cited by
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TL;DR: This work has shown that combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries.
Abstract: Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

14,213 citations

Journal ArticleDOI
TL;DR: Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density.
Abstract: In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

7,642 citations

Journal ArticleDOI
15 Nov 2001-Nature
TL;DR: Recent progress in the search and development of innovative alternative materials in the development of fuel-cell stack is summarized.
Abstract: Fuel cells convert chemical energy directly into electrical energy with high efficiency and low emission of pollutants. However, before fuel-cell technology can gain a significant share of the electrical power market, important issues have to be addressed. These issues include optimal choice of fuel, and the development of alternative materials in the fuel-cell stack. Present fuel-cell prototypes often use materials selected more than 25 years ago. Commercialization aspects, including cost and durability, have revealed inadequacies in some of these materials. Here we summarize recent progress in the search and development of innovative alternative materials.

6,938 citations

Journal ArticleDOI
24 Jun 2011-Science
TL;DR: This work synthesized a porous carbon with a Brunauer-Emmett-Teller surface area, a high electrical conductivity, and a low oxygen and hydrogen content that has high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes.
Abstract: Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

5,486 citations