A high conductivity Cs2.5H0.5PMo12O40/polybenzimidazole (PBI)/H3PO4 composite membrane for proton-exchange membrane fuel cells operating at high temperature

A high conductivity composite proton-exchange membrane Cs2.5H0.5PMo12O40 (CsPOM)/polybenzimidazole (PBI) for use in hydrogen proton-exchange fuel cells has been prepared. The CsPOM composite membrane is insoluble in water. The composite membrane doped with H3PO4 showed high-proton conductivity (>0.15 S cm−1) and good thermal stability. 31P NMR analysis has suggested the formation of a chemical bond between the CsPOM and PBI in the composite membrane. The performance of the membrane in a high-temperature proton-exchange membrane fuel cell (PEMFC) fueled with hydrogen was better than that with a phosphoric acid-doped PBI membrane under the same conditions and at temperatures greater than 150 °C. The CsPOM/PBI composite would appear to be a promising material for high-temperature PEMFC applications.