Effect of catalyst layer on fatigue life and fracture mechanisms of fuel cell membrane

Abstract Perfluorosulfonic acid (PFSA) membrane in polymer‐electrolyte fuel cells bears cyclic mechanical stress during humidity cycles under actual operation conditions, and its durability severely influences the life of fuel cells. However, the fatigue failure mechanisms of membranes are still not clear. In order to investigate the effect of catalyst layer on the fatigue life and fatigue fracture mechanisms of PFSA membranes, fatigue tests of Nafion 212 membranes and two catalyst‐coated membranes (CCMs) are conducted. The morphologies of membranes at different stages of fatigue crack initiation and propagation are identified. It is found that crack initiates from both surfaces of Nafion 212 membrane. Compared with Nafion 212 membrane, the fatigue life of single‐sided CCM increases by more than three times, while that of double‐sided CCM increases by 13 times. Such a phenomenon is ascribed to the protection of catalyst layer on membrane surface, which delays fatigue cracks initiation.