Crack evolution during the film drying process of fuel cell microporous layer ink

Study on the film crack formation process of microporous layer (MPL) in fuel cells is necessary as the size of cracks substantially affects fuel cell durability. In-situ characterization of crack evolution in the full MPL ink drying process is essential to understand the crack formation mechanism. In this work, quasi in-situ crack evolution in the full MPL ink drying process under different stages is comprehensively investigated using ESEM, PLM , and regular SEM . A crack formation with subsequent crack healing mechanisms is discovered. Physiochemical characterizations indicated that the crack formation process is related to the evaporation of isopropanol, whereas the crack healing process is related to the subsequent evaporation of water. Experiments on solvent composition further indicate that the final crack size depends on the ink dispersion during the drying process. Furthermore, the optimal 1/2 IPA/water weight ratio formulation is proposed for the resulting MPL with fewer cracks.