Sulfonated polyimide membrane coated with crosslinkable layer for direct methanol fuel cell

The system composed of hydrocarbon membrane and Nafion-based electrode usually exhibits poor interfacial stability between the membrane and the electrode. In this work, to enhance interfacial stability, crosslinkable materials were coated on sulfonated polyimide membrane and they were crosslinked at the interface during the hot-pressing process of membrane/electrode assembly (MEA). The introduction of crosslinkable layer increased open circuit voltage by reducing methanol crossover, however, it reduced electrochemical active surface area (EAS) of the catalyst. With the enhancement in interfacial adhesion, new MEA with the crosslinked layer could maintain the stable interface after long-term operation compared to the conventionally manufactured MEA without crosslinkable layer.