Durability of novel sulfonated poly(arylene ether) membrane in PEFC operation

A novel proton conducting polymer electrolyte membrane, poly(arylene ether) ionomer containing sulfofluorenyl groups (SPE-1), was subjected to long term fuel cell operation. High durability of the SPE-1 membrane was confirmed by single cell test at 80 °C and at a constant current density of 0.2 A/cm2. Under 90% RH operation, superior hydrolytic stability of the SPE-1 membrane was demonstrated even after 5000 h with no noticeable degradations with respect to cell performances, ion exchange capacity, thickness, and molecular weight. Under 60% RH operation, some change in the molecular weight was observed after 2350 h presumably due to the oxidative degradation caused by the increased cross-over of reactant gases through the membrane.