Effect of non-active area on the performance of subgasketed MEAs in PEMFC

Subgaskets are usually applied to a catalyst-coated membrane (CCM) for the edge-protection of the electrolyte membrane and easy handling. They cover the peripheral region (non-active area) of CCM and have a defined window (active area) for accommodating the electrode. In this study, three subgasketed CCMs with different configurations were designed with a laboratory-scale 5 cm² fuel cell and the effects of the components underneath the subgaskets on the electrochemical properties of CCMs and cell performance were investigated by several electrochemical techniques. The results reveal that part of the catalyst layer under the subgaskets is activated for reaction area, leading to slightly higher electrochemical surface area (ESA), higher H₂ crossover, and smaller shorting resistance. The non-active region of subgasketed CCM has little impact on proton resistance in the catalyst layer, oxygen reduction reaction (ORR) kinetics, and limiting current, but has adverse effects on cell performance in the low current region under dry conditions due to increased hydrogen crossover. The findings could provide guidelines for subgasket design and application in laboratory-scale fuel cells.