Model-Based Investigation of Recombination Interlayers in PEM Water Electrolysis: Concentration Profiles, Efficiency, and Operational Limits

Abstract

Platinum-based recombination interlayers (ILs) are a promising approach to mitigate hydrogen and oxygen crossover during proton exchange membrane (PEM) electrolysis. Until now, there are only experimental investigations on this topic, which demonstrate the integral behavior of a PEM electrolysis cell with an IL but do not resolve local effects. This paper addresses these issues by proposing a first model-based approach to investigate the effects of ILs in PEM water electrolysis cells. We focus on local concentration profiles, crossover fluxes, Faraday efficiency, operational limits, and heat generation. The experimentally validated model shows that the IL substantially affects the local concentrations of dissolved hydrogen and oxygen. Depending on pressure condition and current density, different species can limit the recombination reaction in the IL. The results show that ILs can extend the operational window even for high cathode pressures and thin membranes if enough oxygen is present in the IL to recombine the permeating hydrogen. Additionally, we demonstrate that ILs do not influence the Faraday efficiency of the cell due to two counteracting loss mechanisms. Finally, our simulations indicate that the heat generation from the recombination reaction in the IL has almost no effect on the temperature distribution in the cell.