Mechanism model for long-term degradation failure of PEM water electrolyzers

Abstract One of the bottlenecks restricting the large-scale commercialization of proton exchange membrane (PEM) electrolyzers lies in their poor durability. Due to numerous degradation categories and complex degradation mechanisms within electrolyzers, it is still difficult to quantify the ratio of one single mechanism on the overall degradation through experiments, making it impossible to fully understand the degradation characteristics. A mechanistic model for simulating the degradation process in PEM electrolyzers is proposed in this study. It describes three dominant degradation processes, including ionomer degradation, IrO 2 dissolution, and titanium passivation and corrosion. Then, these three degradation sub-models are coupled into a three-dimensional full-electrolyzer model to reveal the mechanism of long-term operation failure of electrolyzers. It captures the coupling mechanism between degradation and internal heat and mass transfer process, revealing the rapid electrolyzer degradation in the early stage is mainly caused by titanium and ionomer degradation. Increasing the temperature and current density accelerate degradation, that is, temperature primarily accelerates IrO 2 and ionomer degradation, while current density mainly accelerates IrO 2 and Ti degradation. Under low-temperature and low-current-density conditions, electrolyzer failure is mainly due to the voltage reaching the failure criterion; in contrast, electrolyzer failure is more likely caused by IrO 2 dissolution under high-temperature and high-current-density conditions. The developed model provides a foundation for understanding the mechanism of PEM water electrolyzer’s degradation and enhancing the application durability.