Research and Development on Direct Polymer Electrolyte Fuel Cells

Direct fuel cells using a liquid fuel are ideal power sources for use in mobile electronics and transportation. Research and development on direct fuel cells (direct-fueled fuel cells) using a polymer electrolyte membrane were carried out. Biomass fuels, including L-ascorbic acid, ethanol and D-glucose, were studied as fuels. A direct L-ascorbic acid fuel cell could be operated even without an anode catalyst. The maximum power density of direct ethanol and glucose fuel cells was significantly increased by the use of an anion-exchange membrane. Hydrazine and borohydride were studied as carbon-free fuels. An anion-exchange membrane was needed in the direct hydrazine PEM fuel cell to suppress the crossover of hydrazinium cation. A rhodium porphyrin molecular catalyst was developed as an anode catalyst for use in direct borohydride fuel cells. Rhodium porphyrin catalysts suppress the generation of hydrogen due to the hydrolysis of borohydride much more than a platinum catalyst.