Early-stage performance degradation mechanisms of proton-exchange membrane water electrolysis under high operating current densities

Boosting the operating current density in proton-exchange membrane water electrolysis (PEMWE) systems is a promising approach to reduce equipment cost and operational expenses. However, the rapid voltage loss at high current densities during the initial operational phase is often overlooked by mistakenly considered as a mere "conditioning stage", which significantly diminishes its actual impact. Gaining a deeper understanding of these early-stage degradation mechanisms is crucial for enhancing the durability and performance of PEMWE systems. This research conducts a comprehensive analysis of PEMWE degradation mechanisms during the critical first 168 h of operation, particularly at high current densities. The durability test revealed a degradation rate of 1.14 mV/h when operating at a current density of 3 A/cm2. The presence of both reversible and irreversible degradation types is elucidated through recovery experiments. The irreversible voltage loss, primarily due to changes in the pore structure of the anode catalyst layer (ACL), accounts for 68.23 % of the total voltage loss. The reversible voltage loss, mainly attributed to bubble aggregation within the ACL pores, contributing to the rest. This study provides a new perspective to mitigate these effects, ensuring the practical and economic viability of PEMWE systems in the transition to green hydrogen production.