Internal kinetic process revelation of electrochemical impedance spectroscopy of proton exchange membrane water electrolyzer by the impedance dimension model and distribution of relaxation times

Electrochemical impedance spectroscopy (EIS) is an effective tool for analyzing performance of proton exchange membrane water electrolyzer (PEMWE). Currently, there is a lack of research on the allocation of kinetic process from the perspective of mechanistic models. To reveal the correspondence between the kinetic processes of PEMWE and EIS, a 2-D impedance model of PEMWE is developed in this study. Based on this model, the relationship is decoupled by configuring system dynamics and distribution of relaxation times method. It is found that the inductive effect caused by water transport in membrane leads to a 14.9% underestimation of the mass transfer impedance. Accordingly, an EIS analysis method combining the distribution of relaxation times and the equivalent circuit model is proposed. This work decouples different electrochemical kinetic processes from a mechanistic perspective and provide improved guidance for the application and analysis of EIS.