Degradation Mechanisms in PEM Electrolyzers – Occurrence, Relevance and How We Can Measure Them

Polymer Electrolyte Membrane (PEM) electrolyzers are a promising technology for the production of green hydrogen especially for the use with variable renewable energy sources. One remaining challenge is the degradation of the electrolyzer during long-term operation. A multitude of degradation mechanisms can affect the different components of the electrolyzer, as can be seen in Figure 1. In addition, the interaction between different components and mechanisms leads to a high complexity. A lack of harmonized testing protocols impedes comparison between different studies. While membrane thinning and anode catalyst dissolution tend to be most discussed in literature, it remains unclear whether these results accurately reflect the mechanisms that operators find most concerning. For this reason, we conducted a survey among PEM electrolysis experts in both academia and industry, with almost 50 total participants. Based on this survey supplemented with literature analysis, we developed indicators of measurements independent from electrochemical analysis. These allow for the quantification of likely degradation mechanisms contributing to the loss of efficiency or failure of an electrolyzer, as well as mechanisms that occur less frequently but have a significant negative impact on the operability of the electrolyzer. Additional monitoring during operation and post-mortem analysis can contribute greatly towards the development of PEM electrolyzers with stable and efficient long-term operation.