Characterization of A Typical Alkaline Hydrogen Electrolyzer Using Electrochemical Impedance Spectroscopy

This research presents a comprehensive electrochemical characterization of the Teledyne HMXT-100 alkaline hydrogen electrolyzer through electrochemical impedance spectroscopy (EIS) analysis conducted across a frequency range of 10 kHz to 100 mHz, with systematic evaluation of equivalent circuit model (ECM) parameters under varying operational current densities. The study investigates the electrolyzer's impedance behavior at six distinct current levels (221.8 A, 210.3 A, 199.6 A, 172.2 A, 147.3 A, and 125.1 A), enabling detailed analysis of how current density variations affect the electrochemical processes within the alkaline electrolysis system. EIS measurements reveal characteristic impedance signatures that provide insights into ohmic resistance, charge transfer kinetics, and mass transport phenomena, with the equivalent circuit model successfully identifying individual contributions from electrolyte resistance, electrode kinetics, and bubble formation effects across the tested current range. The characterization demonstrates that current density significantly influences the electrolyzer's impedance response, with higher currents generally reducing charge transfer resistance while potentially increasing mass transport limitations due to enhanced gas bubble formation. The developed ECM framework enables quantitative separation of individual loss mechanisms, providing valuable diagnostic capabilities for understanding alkaline electrolyzer performance optimization and degradation patterns. This systematic approach to electrolyzer characterization through wide-frequency EIS analysis offers practical insights for improving alkaline water electrolysis efficiency and establishing robust operating parameters for hydrogen production systems, contributing to the advancement of sustainable energy conversion technologies.