Influence of the operation mode on PEM water electrolysis degradation

This paper compares the performance over time of seven different operation modes with the scope of investigating realistic degradation responses of a polymer electrolyte membrane water electrolysis (PEM WE) to different operation modes for grid-balancing services. Among these modes are constant current and constant voltage operations at different temperatures and current cycling operations, including a solar profile. It was found that faster current cycling improved the overall cell performance over the test period of 500 h, mainly due to a decrease in total ohmic resistance, which is also observed during the break-in phase preceding the experiments. Dynamic operation led to more severe fluoride emission from the catalyst binder, which improved the performance in terms of cell potential but could be a concern for long term degradation as membrane thinning promotes higher gas crossover. All other operation modes on the other hand suffered from an increase in total ohmic resistance, leading to an overall performance decrease, which is suspected to be due to the passivation of the Ti components. Higher operating temperatures were found to enhance cell performance, but are detrimental from a durability point of view since they exacerbate both membrane thinning and passivation processes.