A method for preparing polybenzimidazole or polybenzimidazole blend membranes
and
fabricating gas diffusion electrodes and membrane-electrode assemblies is provided
for a high temperature polymer electrolyte membrane fuel cell. Blend polymer electrolyte
membranes based on PBI and various thermoplastc polymers for high temperature polymer
electrolyte fuel cells have also been developed. Miscible blends are used for solution
casting of polymer membranes (solid electrolytes). High conductivity and enhanced
mechanical strength were obtained for the blend polymer solid electrolytes. With
the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole
and other thermoplastics as binder, the carbon-supported noble metal catalyst is
tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture,
electrodes are assembled with an acid doped solid electrolyte membrane by hot-press.
The fuel cell can operate at temperatures up to at least 200 C. with hydrogen-rich
fuel containing high ratios of carbon monoxide such as 3 vol % carbon monoxide
or more, compared to the carbon monoxide tolerance of 10-20 ppm level for Nafion-based
polymer electrolyte fuel cells.