Impact of Pressure and Temperature on Hydrogen Permeation in PEM Water Electrolyzers Operated at Asymmetric Pressure Conditions

The present work investigates the hydrogen permeation through a polymer electrolyte membrane (PEM) of a fumea EF-40 catalyst coated membrane (CCM) during water electrolysis. The permeation rate is measured at different cell temperatures and different pressure gradients across the membrane. The determined permeation fluxes show a quadratic dependence on pressure difference. This can be described qualitatively very well with a permeation model that considers a diffusive and convective hydrogen transport through the membrane. The determined diffusive permeability coefficient KeffP,diff = 2.95E-14 mol/(m s Pa) at 60 °C and its temperature dependence agrees very well with comparable literature values. The proposed convective permeability coefficient KeffP,conv = 9.02E-21 mol/(m s Pa²) at 60 °C indicates a high hydraulic permeability for the investigated EF-40 in comparison with recently reported values for Nafion membranes.