Improving stability of reinforced composite membrane with hydrophilic interlayer coating

Coating a reinforced composite membrane with a hydrophilic Pt layer can substantially improve the durability of polymer membranes used in fuel cell applications. In this study, we investigated the performance and durability of Aquivion/expanded polytetrafluoroethylene (ePTFE)-reinforced composite membranes with varying Pt contents. We introduced a Pt coating onto ePTFE via magnetron sputtering and characterized the Pt layer using scanning electron microscopy and X-ray photoelectron spectroscopy. As the amount of Pt coating increased, the surface of ePTFE became more hydrophilic; thus, the Pt-impregnated composite membrane was better than the bare composite membrane. We evaluated the fuel cell performance through a single-cell test following membrane electrode assembly fabrication, and performed an accelerated degradation test by maintaining the cell at an open circuit voltage at 90 °C and low humidity (30% relative humidity) for 144 h. Compared to the pure composite membrane, the Pt-coated composite membrane showed less degradation and a lower fluorine emission rate. These results indicated that Pt-coated composite membranes are potentially suitable candidates for use in proton exchange membrane fuel cells.