Comparative Analysis of Degradation Characteristics in a Proton Exchange Membrane Fuel Cell under High-Current-Density (HCD)

Proton exchange membrane fuel cells (PEMFCs) face commercialization barriers mainly due to power density limitations and durability concerns. It necessitates durability analysis under high current density (HCD) operating conditions to advance PEMFC large-scale applications. In this study, a single PEMFC is subjected to 500 h durability tests at current densities of 3000 mA cm –2 and 1000 mA cm –2, respectively, and the degradation characteristics of PEMFC under HCD are investigated. The results show that the PEMFC operated at HCD exhibited a more severe degradation, including a 21.82% maximum power decline and 20.12% electrochemical active surface area (ECSA) reduction, even reaching its end of life (EOL). In comparison, the corresponding degradation at low current density (LCD) is 2.23% and 11.69%, respectively. The predominant degradation mechanisms at HCD are attributed to exacerbated water flooding, which induces catalyst layer (CL) structural degradation and Pt catalyst agglomeration. Furthermore, the degradation under HCD conditions is less uniform both temporally and spatially compared to the corresponding degradation at LCD. These findings emphasize that effective water management strategies are essential for achieving sustainable long-term operation of high-power-density PEMFCs.