A simplified measurement method for gas permeability in multilayer polymer electrolyte membranes

Polymer electrolyte membranes (PEMs) play a crucial role in determining the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs), particularly by regulating gas crossover and facilitating ion conduction. In this study, a simple measurement setup was developed using galvanic and semiconductor sensors to evaluate the oxygen and hydrogen permeabilities of multilayer PEMs under various humidity and temperature conditions. A sandwich-structured membrane (SSM), composed of a high-gas-barrier layer of poly(vinyl alcohol)/poly(vinyl sulfonic acid) (PVA/PVS) between two Nafion layers, was compared with a conventional Nafion membrane. The SSM exhibited reduced oxygen permeability and enhanced chemical durability by suppressing radical formation. Under identical conditions (90 °C, 30% relative humidity), oxygen permeability was reduced to approximately one-third that of the conventional Nafion membrane. However, under high humidity, the permeability increased owing to the swelling of the PVA/PVS interlayer. These findings emphasize the need to optimize the interlayer structure and polymer composition to address the challenges posed by humid operating conditions. The proposed measurement method provides a simple and practical approach for quantitatively evaluating gas transport in PEMs, thereby supporting the accelerated development of advanced membrane materials for PEMFC applications.