Preparation of intermediate-temperature proton conducting materials utilizing reaction of phosphate glass and organic molecules

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An intermediate-temperature proton-conducting amorphous material was prepared utilizing the reaction of zinc metaphosphate glass powders with benzimidazole (BIm). The anhydrous material showed almost no decrease in weight even after heating at 200℃. It showed electrical conductivities of 10-100 pS-cml at the intermediate temperatures of 170-230℃: the activation energy for electrical conduction (~1.0 eV) was larger than that for proton transport between benzimidazole molecules. For improving the electrical conductivities, nanometer-sized zirconium phosphate particles with mobile protons at their surface were hybridized with the amorphous materials. The resulting materials showed two-order magnitude larger conductivities than those before hybridization, and small activation energy of ~16 kJ/mol. NMR analysis implied that the strength of hydrogen bonding and the amount of mobile protons increased at around the surface of the nano-particles. MEA (membrane-electrode-assembly) using the material as the electrolyte worked with a maximum power density of 111 mW cm' when utilized in an H2/02 fuel cell at 150℃.