Challenges and important considerations when benchmarking single-cell alkaline electrolyzers

This study outlines an approach to identifying the difficulties associated with the benchmarking of alkaline single cells under real electrolyzer conditions. A challenging task in the testing and comparison of different catalysts is obtaining reliable and meaningful benchmarks for these conditions. Negative effects on reproducibility were observed due to the reduction in conditioning time. On the anode side, a stable passivation layer of NiO can be formed by annealing of the Ni foams, which is even stable during long-term operation. Electrical contact resistance and impedance measurements showed that most of the contact resistance derived from the annealed Ni foam. Additionally, analysis of various overvoltages indicated that most of the total overvoltage comes from the anode and cathode activation overpotential. Different morphologies of the substrate material exhibited an influence on the performance of the alkaline single cell, based on an increase in the ohmic resistance.