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Title: Critical survey on electrode aging in molten carbonate fuel cells

Abstract

To evaluate potential electrodes for molten carbonate fuel cells, we reviewed the literature pertaining to these cells and interviewed investigators working in fuel cell technology. In this critical survey, the effect of three electrode aging processes - corrosion or oxidation, sintering, and poisoning - on these potential fuel-cell electrodes is presented. It is concluded that anodes of stabilized nickel and cathodes of lithium-doped NiO are the most promising electrode materials for molten carbonate fuel cells, but that further research and development of these electrodes are needed. In particular, the effect of contaminants such as H/sub 2/S and HCl on the nickel anode must be investigated, and methods to improve the physical strength and to increase the conductivity of NiO cathodes must be explored. Recommendations are given on areas of applied electrode research that should accelerate the commercialization of the molten carbonate fuel cell. 153 references.

Authors:
Publication Date:
Research Org.:
Argonne National Lab., IL (USA)
OSTI Identifier:
5625338
Report Number(s):
ANL-79-55
DOE Contract Number:
W-31-109-ENG-38
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; ELECTRODES; AGING; CORROSION; POISONING; SINTERING; HIGH-TEMPERATURE FUEL CELLS; ADDITIVES; ANODES; CARBONATES; CATHODES; COBALT; CONTAMINATION; COPPER; DATA; ELECTRIC CONDUCTIVITY; EVALUATION; HIGH TEMPERATURE; HYDROCHLORIC ACID; HYDROGEN SULFIDES; IRON; MATERIALS; MOLTEN SALTS; NICKEL; NICKEL ALLOYS; NICKEL OXIDES; OXIDATION; PERFORMANCE; REVIEWS; SILVER; STAINLESS STEELS; ALLOYS; CARBON COMPOUNDS; CHALCOGENIDES; CHEMICAL REACTIONS; CHROMIUM ALLOYS; CORROSION RESISTANT ALLOYS; DIRECT ENERGY CONVERTERS; DOCUMENT TYPES; ELECTRICAL PROPERTIES; ELECTROCHEMICAL CELLS; ELEMENTS; FABRICATION; FUEL CELLS; HYDROGEN COMPOUNDS; INFORMATION; INORGANIC ACIDS; IRON ALLOYS; IRON BASE ALLOYS; METALS; NICKEL COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; SALTS; STEELS; SULFIDES; SULFUR COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; 300503* - Fuel Cells- Materials, Components, & Auxiliaries

Citation Formats

Kinoshita, K. Critical survey on electrode aging in molten carbonate fuel cells. United States: N. p., 1979. Web. doi:10.2172/5625338.
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Kinoshita, K. Critical survey on electrode aging in molten carbonate fuel cells. United States. doi:10.2172/5625338.
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Kinoshita, K. Sat . "Critical survey on electrode aging in molten carbonate fuel cells". United States. doi:10.2172/5625338. https://www.osti.gov/servlets/purl/5625338.
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@article{osti_5625338,
title = {Critical survey on electrode aging in molten carbonate fuel cells},
author = {Kinoshita, K.},
abstractNote = {To evaluate potential electrodes for molten carbonate fuel cells, we reviewed the literature pertaining to these cells and interviewed investigators working in fuel cell technology. In this critical survey, the effect of three electrode aging processes - corrosion or oxidation, sintering, and poisoning - on these potential fuel-cell electrodes is presented. It is concluded that anodes of stabilized nickel and cathodes of lithium-doped NiO are the most promising electrode materials for molten carbonate fuel cells, but that further research and development of these electrodes are needed. In particular, the effect of contaminants such as H/sub 2/S and HCl on the nickel anode must be investigated, and methods to improve the physical strength and to increase the conductivity of NiO cathodes must be explored. Recommendations are given on areas of applied electrode research that should accelerate the commercialization of the molten carbonate fuel cell. 153 references.},
doi = {10.2172/5625338},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Dec 01 00:00:00 EST 1979},
month = {Sat Dec 01 00:00:00 EST 1979}
}
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Technical Report:
View Technical Report (3.50 MB)
DOI:  10.2172/5625338
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  • Fuel cell models developed so far can be grouped into two categories: performance models and electrode models. Performance models use a resistance concept. They are useful for determining effects of flow rates, temperature, geometry, etc., on fuel cell performance. A useful electrode model called an agglomerate model was developed for the phosphoric acid cell. Such models were used to improve electrode structures. Electrode modeling of molten carbonate fuel cells is, as yet, in a very primitive state.

  • ; ; ; ...
    The high temperature apparatus for investigations of electrode kinetics of oxygen reduction on test electrodes in molten carbonates was tested using Li/sub 2/CO/sub 3/ melt and a gold flag test electrode. Potential sweep data for oxygen reduction reaction at the gold electrode in Li/sub 2/CO/sub 3/ melt were obtained and the results were found to be in agreement with the available data in literature. AC impedance measurements, as a function of frequency, are in progress to evaluate the kinetic parameters for peroxide reduction in Li/sub 2/CO/sub 3/melt. A complex nonlinear least square parameter estimation program, based on equivalent circuit model,more » is employed to analyze the ac impedance data. One of the designs being considered for the microelectrode (to be used to determine the transport parameters of the intermediate species (O/sub 2/- and O/sub 2//sup 2/-) and the electrode kinetic parameters for oxygen reduction in molten carbonates) is a fine wire (diameter of 25 ..mu..m or less) anchored on an alumina tube with a ceramic adhesive. This design is being initially tested for oxygen reduction in an aqueous medium. For this purpose, a cylindrical microelectrode of gold is being used in aqueous KOH solution for the simultaneous determination of diffusion coefficient and solubility of oxygen from the transient measurements of the potential step experiments. Several ceramic adhesives are being evaluated for their stability in molten carbonate environment. The stable ceramic adhesive will be utilized for leak-proof sealing of the test electrode (fine wire) to the open end of the alumina tube. 9 figs.« less

  • ; ;
    The oxygen cathode of the molten carbonate fuel cell is still not well understood because of the uncertain nature of the reaction mechanism. The objectives of this project include a study to examine the kinetics of oxygen reduction in molten carbonate fuel cells by unambiguous methods that allow the determination of the rate determining steps and the reaction parameters. The data from such kinetic studies require sophisticated analytical techniques for obtaining the kinetic mechanism that best fits the data and, consequently, the best estimates of the reaction parameters. 1. A program has been written to simulate the reaction sequences formore » oxygen reduction in a molten carbonate fuel cell at a rotating disk electrode. 2. The reaction sequence for the superoxide mechanism was simulated using assumed and literature values for the reaction parameters.« less

  • ; ; ; ...
    The high temperature equipment necessary for the investigation of oxygen reduction kinetics using microelectrodes was set up. Three types of microelectrodes were designed and fabricated. Experiments are underway to examine the microelectrodes in respect to (1) their stability in the molten carbonate environment; (2) oxygen reduction kinetics and mass transport parameters in aqueous electrolytes for comparison with similar results using other techniques; and (3) oxygen reduction kinetics and mass transport parameters in molten carbonate electrolytes. The reaction sequences for oxygen reduction in melts of various carbonate mixtures were simulated on the basis of a postulated kinetic model involving the reductionmore » of O/sub 2//sup 2/minus// and O/sub 2/minus// ions at the electrode. Auto-catalytic reactions involving the reaction of O/sub 2//sup 2/minus// and O/sub 2/minus// species with O/sub 2/ and the neutralization reaction of O /sup 2/minus// ions by CO/sub 2/ in the melt were taken into account. Enhancement of oxygen reduction currents occurs at high rates of oxygen dissolution in the melt. Changes in the auto-catalytic reaction rates of O/sub 2//sup 2/minus// and O/sub 2/minus// affect the polarization curves significantly only in the presence of dissolved oxygen in the melt. 8 figs.« less

  • ; ; ; ...
    The oxygen reduction reaction on a gold electrode in lithium carbonate melt was investigated to determine the influence of partial pressure of carbon dioxide and and temperature on electrode kinetic and oxygen solubility by using cyclic voltammetry and impedance analysis techniques. During this quarter, the impedance data were analyzed by a Complex Nonlinear Least Square (CNLS) parameter estimation program to determine the kinetic and the mass transfer related parameters such as charge transfer resistance, double layer capacitance solution resistance, and Warburg coefficient. The estimated parameters were used to obtain the CO{sub 2} reaction orders and apparent activation energies for themore » exchange current density and the mass transfer parameter (D{sub O}{sup 1/2}C{sub O}*). 7 refs., 11 figs., 4 tabs.« less