Polyphosphazene-based polymer electrolyte membrane fuel cells

The newly developed polyphosphazene (POP)-based proton conducting membranes to be used on polymer electrolyte membrane fuel cells (DMFC) was studied. Sulfonated and phosphonated POP had significant increases in conductivity with increasing temperature, although these values remained lower than that of Nafion 117. The results for the methanol permeability measurements of sulfonated and phosphonated POP at ambient temperatures showed significantly lower capacity for methanol cross-over when compared to Nafion 117, leading to promising candidates for further DMFC testing. Sulfonated POP was superior (in terms of selectivity) to Nafion 117 at below 85°C, while the phosphonated POP was superior to Nafion 117 at 22°-125°C. The maximum power density for the sulfonimide POP-based fuel cell was comparable to the Nafion-based MEA, as well as to the results of Wilson and Gottesfeld for Nafion 117 based fuel cells.