The effect of cell position in a PEM electrolyzer stack: Impedance and numerical analysis to explore the role of inductance

This study presents an electrochemical impedance analysis of eight proton exchange membrane (PEM) water electrolysis cells connected in series. By adopting a more comprehensive equivalent circuit model that explicitly accounts for low-frequency inductive behavior, the experimental impedance data were fitted with improved accuracy. In addition to conventional Nyquist and Bode representations, an alternative visualization of the impedance response is employed to facilitate the visual deconvolution of the different model contributions. The impedance spectra of individual cells exhibit distinct differences, primarily associated with operational variations such as temperature gradients and anodic fluid flow velocity, which were obtained from simulations performed using COMSOL Multiphysics. The results highlight the potential of impedance-based analysis as a non-intrusive method to access both cell-specific information and contributions from individual components within each cell, providing a potential pathway toward real-time monitoring of performance and degradation.