Electrochemical characteristics of acid electrolytes for fuel cells. Final report, January 1, 1989-June 30, 1991
The electrochemical evaluation of new perfluorinated fuel cell electrolytes provided by GRI contractors at Clemson and Iowa shows the kinetics for O2 reduction on Pt improves with these acids compared to with phosphoric acid. The improvement is mainly due to the lesser tendency of these acids to adsorb on Pt. Kinetics do not have a strong dependence on pH or O2 solubility when mass transport is not involved. Concentrated sulfonyl acids were usually found to wet Teflon resulting in the flooding of Teflon-bonded gas fed electrodes and poor performance at high current densities. These perfluorinated electrolytes were, however, found to be useful as performance enhancing additives to concentrated phosphoric acid in some cases. The alpha,omega-bis-phosphonic acid with a perfluoroethylene bridge gave superior performance compared to phosphoric acid at elevated temperatures (up to 200 degrees C) for 500 hours. Bis-phosphonic acids with higher CF2 to PO3H2 ratios dehydrated more readily at elevated temperatures, resulting in resistive voltage losses. New perfluorinated phosphonic acid containing olefins were found to be polymerizable. This suggests that with a reasonable synthetic effort, new kinds of ionomer membranes are attainable, and these may be superior to Nafion for fuel cell applications.
- Research Organization:
- Case Western Reserve Univ., Cleveland, OH (United States). Case Center for Electrochemical Sciences
- OSTI ID:
- 7002953
- Report Number(s):
- PB-93-124907/XAB; CNN: GRI-5084-260-1108
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
300502 -- Fuel Cells-- Performance & Testing
300505* -- Fuel Cells-- Electrochemistry
Mass Transfer & Thermodynamics
ADDITIVES
CATHODES
CHEMICAL REACTIONS
CHEMISTRY
DIRECT ENERGY CONVERTERS
ELECTROCHEMICAL CELLS
ELECTROCHEMISTRY
ELECTRODES
ELECTROLYTES
EVALUATION
FLUORINATED ALIPHATIC HYDROCARBONS
FLUORINE COMPOUNDS
FUEL CELLS
HALOGEN COMPOUNDS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
KINETICS
LOSSES
MASS
MATERIALS
MEMBRANES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PERFORMANCE
PETROCHEMICALS
PETROLEUM PRODUCTS
PHOSPHONIC ACIDS
PHOSPHORIC ACID
PLASTICS
POLY
POLYETHYLENES
POLYTETRAFLUOROETHYLENE
REACTION KINETICS
REDUCTION
SOLUBILITY
SYNTHETIC MATERIALS
TEFLON
TRANSPORT