750 EW Perfluorosulfonic Acid Composite Membranes With Stabilized Phosphotungstic Acid for High Temperature/Low Relative Humidity PEM Fuel Cells

750 EW perfluorosulfonic acid composite membranes with 15% phosphotungstic acid (FSEC3) were prepared and characterized for high temperature/low relative humidity PEM fuel cell. The membranes at different stages of fabrication, i.e., as cast, Cs treated, and protonated were evaluated with FTIR, XRD, TGA, water uptake, TEM and SEM. By using a low relative humidity atmosphere during the fabrication process, particle sizes of ~20 nm for Cs-PTA within the membrane were achieved. At 30{degree sign}C and 80% relative humidity a conductivity of 80 mS/cm for FSEC3 membrane was measured, which is 2.5 times higher than Nafiona^ 112 conductivity at the same conditions and exceeds the current DOE milestone of 70mS/cm.