Dynamic Lumped Cell-Level Model of Chemical Membrane Degradation in PEM Electrolysis: Impact of Pressure and Time Dependence

Chemical membrane degradation has a significant impact on the lifetime of PEM electrolyzers. For a comprehensive understanding of chemical membrane degradation, cell-level models are useful. However, existing cell-level models ignore the dynamic degradation process of PFSA membranes and do not consider the influence of operating parameters, such as pressure. To address these limitations, we present a dynamic cell-level model in which chemical membrane degradation is represented by the fluoride release rate (FRR). The model is lumped (0D in space), and parameters are estimated with literature data using a pseudo–steady-state approach. The model is then applied to investigate the influence of pressure. The results show increased FRR and H2O2 concentrations at higher pressures due to enhanced O2 crossover. A maximum in the degradation rate arises at intermediate current densities due to the interplay of electro-osmotic drag and back-diffusion, which maximizes in-membrane radical (•OH) concentrations, while at higher current densities washout and Fe2+ limitation reduce them. Time-dependent simulations with full dynamics further indicate that the maximum is reached only after several thousand hours.