Analyses on the structure and dynamics of polymer electrolyte membranes

Abstract Polymer electrolyte membranes (PEMs), such as Nafion, have been widely employed as separators between the anode and cathode electrodes in various fuel cells and electrolyzers due to their excellent ionic conductivity and durability. However, several critical aspects of PEMs, including the mechanisms of proton conduction, remain poorly understood. Moreover, the native, degraded, and regenerated states of PEMs require further investigation to enhance their performance. Consequently, comprehensive integrated analyses, particularly those integrating multiscale and multiple time-scale techniques, are essential not only for understanding the behavior of PEMs but also for improving their functional properties. In this context, we briefly overview various analytical methods used for structural and dynamical characterization of PEMs, including the self-diffusion and translational dynamics of ions. The application of solid-state nuclear magnetic resonance spectroscopy to the study of PEMs is also reviewed. In addition, in-situ/operando analyses and the integration of artificial intelligence (AI) or machine learning with accumulated analytical data are discussed as emerging strategies for developing new design concepts for PEMs.