Modeling the membrane/CL delamination with the existence of CL crack under RH cycling conditions of PEM fuel cell

Relative humidity (RH) cycling during the frequent startup/shutdown (SUSD) process may lead to the generation and propagation of mechanical defects in the polymer electrolyte membrane (PEM) fuel cell. In this study, a 2D finite element model for the evolution of internal defects in PEM fuel cell is established, and the interfacial behavior of the membrane/catalyst layer (CL) is simulated based on the cohesive zone model (CZM), focusing on the RH cycling effect on the membrane/CL delamination evolution. Emphasis is placed on the evolution of membrane/CL delamination when cracks have been generated in the CL. The results show that the existence of the CL crack aggravates the membrane/CL delamination, and the more the position of the CL crack is off-center, the more serious the delamination propagation is. The initial delamination length (IDL) and interface length synergistically affect the interface behavior of membrane/CL. Higher frequency (or shorter period) and greater amplitude of the RH cycle intensify the membrane/CL delamination.