Mechanical durability characterization and modeling of ionomeric membranes

Abstract Many of the premature failures in proton exchange membrane (PEM) fuel cells are attributed to the crossover of reactant gases through cracks developing in the membrane during fuel cell operation. Postmortem analysis of membranes subjected to fuel cell humidity cycling tests in the absence of electrochemical reaction suggests that membrane cracks are driven by the in‐plane tensile stress state that develop within the membrane during cyclic hygrothermal loading. This article presents an effort to develop a suite of analytical and experimental methods within a framework of viscoelasticity to characterize the mechanical stresses, constitutive properties, strength, and durability/lifetime of proton exchange membranes. The success obtained in accounting for a range of observed phenomena suggests the applicability and usefulness of this framework.