Performance Losses and Recovery from Cation Contaminants in PEM Water Electrolysis

Water contaminants are extremely common cause of failure for polymer electrolyte membrane (PEM) electrolyzers, potentially accounting for >90% of electrolyzer failures in the field. [1] Water contaminants also commonly impact PEM electrolysis devices in a research setting, confusing measurements of cell performance and durability if they are not recognized and properly addressed. Despite this, relatively little published literature has systematically investigated contaminants in PEM electrolysis cells specifically. Better understanding of contaminant impacts may lead to improved strategies to mitigate or recover performance losses as well as improve the consistency and rigor of electrolysis research. Here we will present an investigation of the performance impacts of cation contaminants and their recoverability. This investigation focuses on cation contaminants that are abundant in tap/ground water, which may enter the cell through a failure of the water processing subsystem, and transition metals that may leach out of system components. We will report performance impacts for a representative selection of cations as a function of water concentration and accumulated contaminant dose, with impedance spectroscopy used to understand the origin of performance losses. We will also present multiple diagnostic signatures to help identify presence of contaminants in PEM electrolysis cells. Finally, we will address the recovery of cells with different contaminants and the prospects for improved recovery procedures. [1] Capuano, Chris “Manufacturing Challenges, Opportunities, and Successes for PEM Electrolysis at Scale”, 3rd International Conference on Electrolysis, Golden, CO, 2022.