Long-term performance of polyetheretherketone-based polymer electrolyte membrane in fuel cells at 95C

Chen, J.; Zhai, M.*; Asano, Masaharu; Huang, L.*; Maekawa, Yasunari

A poly(styrenesulfonic acid)-grafted polyetheretherketone (ssPEEK) polymer electrolyte membrane was developed by radiation grafting of ethyl styrenesulfonate (ETSS) onto PEEK film and subsequent hydrolysis. The long-term durability of the ssPEEK membrane was tested in a fuel cell, and it exhibited a lifetime of more than 1,000 h and a slow voltage degradation. After durability test, the catalyst layers were analyzed by XRD and TEM; the membrane was investigated by determining the change in thickness, proton conductivity and amounts of sulfonic acid groups. It was concluded that the degradation of performance in fuel cell was due to the thermal aging of the hydrocarbon membrane exposed to the electrochemical environment using the pure oxygen as the oxidant gas, as well as the Nafion-based catalyst layer being subject to high temperature for a long time, where the Pt catalyst was aggregated and sintered.