AN ADVANCED GAS-DIFFUSION ELECTRODE FOR HIGH-PERFORMANCE PHOSPHORIC-ACID FUEL-CELLS

An extremely thin fluorinated polyethylene (FPE) film was prepared on a carbon black (CB) surface and the properties were studied. It was fo und that polyethylene as the precursor can cover the whole surface of the CB particles with a thin film different from the conventional Tefl on dispersion (PTFE), and it can be fluorinated easily to produce a Te flon-like hydrophobic material. The resulting FPE/CB material showed a distinctive hydrophobic property and a comparable thermal stability c ompared with PTFE under the operating conditions for phosphoric acid f uel cells (PAFCs). An advanced gas diffusion electrode for PAFCs is pr oposed in which a new design concept of the electrode structure is app lied where the functions of electrolyte network and gas network are as signed completely to catalyzed CB and FPE/CB. The cathode optimized in the structure with the new FPE/CB exhibited a high performance for ox ygen reduction compared with cathodes using conventional PTFE owing to the improved catalyst utilization and gas permeability, and showed a potential for long operational life owing to less performance degradat ion resulting from the prevention of flooding of the gas network with electrolyte during operation.