Effects of cycle duration and test hardware in relative humidity cycling of a polymer electrolyte membrane

Abstract

In this study, relative humidity (RH) cycling accelerated stress testing (AST) is pursued on a supplier's catalyst coated membrane (CCM). The experimental design includes three RH cycles and two test cell/membrane electrode assembly (MEA) formats. All three cycles tested are shorter than the Department of Energy (DOE) protocol and model simulations indicate that deep and fast hydration swings could still be retained. Edge failure is observed in one test cell, which is in part responsible for the shorter lifetime in RH cycling as compared to using another test cell and suggests a test hardware harmonization if the lifetime is referenced to a target or compared between different materials. Nevertheless, the trends of H2 crossover versus the number of cycles and overall test time remain consistent for two hardware formats. This finding suggests that RH cycling could be effectively used to investigate a control factor, such as cycle duration, based on a single hardware and material, towards the development of system strategies on a fuel cell vehicle. Furthermore, since the H2 crossover versus RH cycling test time plots exhibit clear separation for three cycles, the frequency and duration of cycles both play a role in determining the membrane lifetime.