Novel evaluation method for degradation rate of polymer electrolytes in fuel cells

A simple and new method has been developed to evaluate the degradation rate of polymer electrolytes caused by the cross-leakage of H2 or O2 in PEFCs. Mixed gas of H2 and air with a constant composition was supplied to a sample powder suspended in water, e.g., consisting of Pt supporting carbon black coated with a perfluorosulfonated acid electrolyte. Fluoride ion released from the electrolyte into the water was quantitatively analyzed as a function of time. The electrolyte was decomposed only when H2, O2, and Pt coexisted. The present method enables to compare the durability of different electrolyte polymers directly under the same controlled environment within a short period.