Experimental study on the degradation of proton exchange membrane water electrolyzers under different dynamic loads and flow field configurations

Proton exchange membrane water electrolyzer (PEMWE) has shown promising potential in green hydrogen production due to high efficiency and pollution-free characteristics. However, their relatively poor lifetime and durability have hindered their widespread commercialization. This study designs experiments to investigate the degradation of PEMWE equipped with two different flow fields under cyclic testing with three different dynamic load combinations, after 60 h of operation. The results of the study indicate that the voltage degradation rate of PEMWE is highest under step load cycling, followed by multi-step load cycling, with the least degradation observed under constant current density conditions. On the other hand, PEMWE equipped with triple serpentine flow field (TSFF) experiences greater degradation compared to parallel flow field (PFF), with the average voltage degradation rate at a current density of 1 A/cm2 being 29% higher for the former than the latter. The Electrochemical impedance spectroscopy (EIS) curves were analyzed using both equivalent circuit fitting and distribution of relaxation times (DRT) methods. The results indicate that the primary factor contributing to the degradation of PEMWE is the increase in charge transfer resistance due to catalyst layer degradation, particularly at the anode. Furthermore, when using the TSFF flow field, the increase rate of the anode charge transfer resistance in PEMWE is 30.41%, which is significantly higher than the 18.28% observed when using the PFF flow field. The conclusions of this study may provide valuable insights into the factors influencing the degradation of PEMWE.