Phosphoric acid doped triazole-containing cross-linked polymer electrolytes with enhanced stability for high-temperature proton exchange membrane fuel cells

Phosphoric acid (PA) leaching is one of the endurance issues for the use of PA-doped polymer electrolytes in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). A chemical cross-linking approach is presented that adequately addresses this issue. The cross-linked membrane (XTPPO) was synthesized from poly (2,6-dimethyl-1,4-phenylene oxide) containing triazole groups (TPPO) on the side chains by in situ casting and click reaction with 1,7-octadiyne. XTPPO exhibited more than 90% of the membrane retained after gel fraction test. The cross-linked membrane showed high thermal stability with TD5% = 325 °C. Cross-linking also led to enhanced oxidative and mechanical stability. PA doping was controlled with the amount of triazole and the degree of cross-linking. The highest proton conductivity measured in the anhydrous condition was 64 mS/cm at 180 °C.