Perfluorinated sulfonic acid ionomer degradation after a combined chemical and mechanical accelerated stress test to evaluate membrane durability for polymer electrolyte fuel cells

Investigating the chemical and mechanical degradation phenomena of polymer electrolyte membranes (PEMs) is crucial, as they significantly influence the electrochemical performance and lifetime of fuel cell electric vehicles. For this, the combined use of chemical and mechanical accelerated stress test (AST) protocols has proven effective and reliable in evaluating PEMs durability within a relatively short period. However, it remains unclear whether the combined AST protocols exclusively affect PEMs durability, since the AST evaluation is performed not in the membrane states but in the membrane-electrode assembly (MEA) state. To address this question, a combined AST protocol consisting of a single cycle involving a chemical degradation phase followed by a mechanical degradation phase, was applied. The influence of the combined AST on both the membrane and electrodes was investigated using a variety of electrochemical evaluations conducted after each cycle. Additionally, the study includes changes in the physical characteristics of each MEA component.