Electrochemical Measurement of the Oxygen Permeation Rate through Polymer Electrolyte Membranes

An electrochemical method is developed for the measurement of the oxygen permeation rate through perfluorosulfonic acid (PFSA) membranes at various temperatures and relative humidities (RH) using a fuel cell setup. The oxygen permeability is determined from the oxygen-crossover-rate limited oxygen reduction reaction (ORR) current. The current vs. applied voltage relationship during the oxygen permeation rate measurement can be fully explained by a kinetic model accounting for the anode and cathode reactions, oxygen transport through the membrane, and oxygen diffusion from the cathode electrode to cathode flow channel. While demonstrated for a PFSA membrane, the presented electrochemical method to quantify the oxygen permeability is also applicable to any other types of proton or hydroxide conducting ionomeric membranes.