Severing the “Switch” of Reverse Current Decay Grants Dynamic Adaptability to Proton Exchange Membrane Electrolyzers

Abstract The direct integration of proton exchange membrane water electrolyzers (PEMWEs) with intermittent renewable energy sources induces severe degradation during frequent start-stop cycling. Although operational strategies can alleviate generic power fluctuations, the intrinsic failure mechanisms of PEMWEs under stepwise dynamic conditions have not been fully clarified. In this study, we investigate the multi-pathway degradation behavior of PEMWEs under high-frequency current step variations and examine the possible contribution of zero-current intervals to degradation. We further reveal that zero-current intervals involve reverse current associated with electrochemical processes, accompanied by residual gases, catalyst structural deterioration, and membrane degradation. To mitigate this degradation, we introduce a titanium mesh-reinforced anode configuration that improves mechanical stability and mitigates localized voltage overshoot. Benefiting from this structural optimization, the PEMWE enables stable operation for 300 h under high-frequency stepwise fluctuations, with a low degradation rate of 0.18 mV h–1. Crucially, a seven-day photovoltaic-electrolysis field test further confirms stable start-stop operation of the optimized electrolyzer under real-world solar irradiance. By elucidating the interplay between electrochemical dynamics and structural evolution, this work proposes a practical engineering strategy verified via laboratory accelerated aging tests and outdoor photovoltaic-electrolysis field tests, which supports the development of applicable green hydrogen systems.