Water electrolysis allows the production of green hydrogen, which will play a key role in the future energy system. While research takes place in small laboratory‐scale electrolysis cells, the findings shall be applied to large industrial‐scale electrolyzer stacks. What conclusions about the behavior of large stacks can be drawn from small lab cell experiments? In this work, the concept of a differential electrolysis cell was developed to answer this question. The novel cell allows control of relevant operating conditions, most importantly the gas content in the electrolyte and the mechanical contact pressure between electrodes and separator, which is hardly possible with existing standard test cells. We demonstrate that both parameters have an important influence on cell performance. The new test cell will allow in‐depth investigation of the observed effects. The cell is configured as an alkaline electrolysis cell, but the concept can be transferred to other types of electrochemical cells. This paves the way to understand and possibly predict the overall performance and limitations of a stack and crucial scaling parameters through small‐scale laboratory experiments.
Ritz et al. (Fri,) studied this question.