Mathematical Modelling of Cation Contamination in a Proton-exchange Membrane

Transport phenomena in an ion‐exchange membrane containing both H⁺ and K⁺ are described using multicomponent diffusion equations (Stefan–Maxwell). A model is developed for transport through a Nafion 112 membrane in a hydrogen‐pump setup. The model results are analysed to quantify the impact of cation contamination on cell potential. It is shown that limiting current densities can result due to a decrease in proton concentration caused by the build‐up of contaminant ions. An average cation concentration of 30 to 40% is required for appreciable effects to be noticed under typical steady‐state operating conditions.