Membrane degradation in PEM water electrolyzer: Numerical modeling and experimental evidence of the influence of temperature and current density

In this work, a 1D polymer electrolyte membrane water electrolyzer (PEMWE) model that incorporates chemical degradation of the membrane is developed to study the influence of temperature and current density on the membrane degradation. In the 1D performance model, electronic and ionic transports through the different cell components are considered together with the electrochemical behavior of the anodic and cathodic catalyst layers. The membrane degradation model describes the oxygen cross-over from the anode to the cathode side, the formation of hydrogen peroxyde at the cathode side together with the subsequent formation of radicals via Fenton reactions involving metal-ion impurities and the membrane degradation. The development of the model is supported by specific single cell experiments to both validate the different modeling assumptions and determine some of the physical parameters involved in the performance and degradation models. The single-cell degradation tests confirm that most of the membrane degradation occurs at the cathode side and also show the strong influence of the temperature on the degradation rate. The effect of the current density on the degradation rate is more complex and presents a maximum at quite low current density. This phenomena, observed in the experiments, is well captured by the model. The model is then used to study the time evolution of the membrane thickness. The coupling between the performance and the chemical degradation models allows to capture the acceleration of membrane thinning.