HIGH-ENERGY EFFICIENCY AND HIGH-POWER DENSITY PROTON-EXCHANGE MEMBRANE FUEL-CELLS - ELECTRODE-KINETICS AND MASS-TRANSPORT

The development of proton exchange membrane (PEM) fuel cell power plants with high energy efficiencies and high power densities is gaining momentum because of the vital need of such high levels of performance for extraterrestrial (space, underwater) and terrestrial (power source for electric vehicles) applications. Since 1987, considerable progress has been made in achieving energy efficiencies of about 60% at a current density of 200 mA/cm2 and high power densities (> 1 W/cm2) in PEM fuel cells with high (4 mg/cm2) or low (0.4 mg/cm2) platinum loadings in electrodes. This article focuses on: (i) methods to obtain these high levels of performance with low Pt loading electrodes - by proton conductor impregnation into electrodes, localization of Pt near front surface; (ii) a novel microelectrode technique which yields electrode kinetic parameters for oxygen reduction and mass transport parameters; (iii) demonstration of lack of water transport from anode to cathode; (iv) modeling analysis of PEM fuel cell for comparison with experimental results and predicting further improvements in performance; (v) recommendations of needed R&D for achieving the above goals.