In-operando impedance spectroscopy study for accelerated lifetime studies of dynamic alkaline water electrolysis under industrial conditions

Dynamic alkaline water electrolysis is positioned to provide high volume, economical green hydrogen when coupled to renewable energy sources. Accelerated lifetime testing (ALTs) reduces development time, but the degradation pathways must be known under industrial operating conditions to establish a meaningful relationship to real-life degradation. In-operando electrochemical impedance spectroscopy (EIS) was run throughout a dynamic range of current densities spanning 0.1–1.5 A cm⁻² under different current profiles simulating steady-state, renewable cycling, and square-wave in 30 wt% potassium hydroxide. The two cells: either a Raney Ni or non-platinum group metal (PGM) anode, exhibited distinct impedance behavior under renewable and square-wave conditions compared to normal steady-state operation. The change of impedance was quantified to derive square-wave acceleration factors of 1.5x for Raney Ni and 2.1x for non-PGM, but for different profiles. These findings highlight the need to develop more purposeful ALTs and how in-operando EIS can be used to study and quantify degradation modes for developing them.