Optimization of Carbon-Supported Platinum Catalysts for Fuel Cell Electrodes

摘要

The objective of this program was to optimize electrodes using the carbon-supported platinum catalysts at the operating conditions required for use in methanol-air, phosphoric-acid electrolyte, fuel cell power plants for U.S. Army applications. Cathodes using proprietary, supported-platinum catalyst, GSA-6, were fabricated with various degrees of hydrophobicity by adjusting the Teflon content in the catalyst layer and by changing the Teflon sintering cycle. These cathodes were tested with supported-platinum anodes in eighteen subscale cells at the Army power plant operating conditions for periods exceeding 5000 hours. The optimum structure, on the basis of peak cell voltage, endurance stability, and manufacturing reproducibility was found to be one containing 47.5% Teflon. A standard United proprietary anode catalyst showed satisfactory peak performance and endurance stability. The cells with optimized electrodes exceeded the program 500-hour performance goal of 0.620V at 200 mA/cubic centimeters by 0.020V. The 6000-hour performance goal of 0.590 V at 200 mA/cubic centimeters was projected to be exceeded by 0.036 to 0.038 V (based on over 4000 hours of operation).