Proton conduction in ionic liquid-modified P2O5–SiO2 glasses

Abstract For use as an electrolyte of the H 2 /O 2 fuel cells operating in the intermediate temperature range under anhydrous conditions, P 2 O 5 –SiO 2 glasses membranes containing ionic liquid were prepared using tetramethoxysilane, methyl-trimethoxysilane, trimethylphosphate and 1-ethyl-3 methylimidazolium-bis (trifluoromethanesulfonyl) imide (EMITFSI) ionic liquid as precursors. The proton conductivity was high 2 × 10 − 3 S/cm at 100 °C and no decrease was observed up to 200 °C under anhydrous condition. We discovered that the EMITFSI molecules are confined in the small-sized pores of the matrix glasses and act to increase the proton transfer in the hybrid membranes. The effect of EMITFSI on the proton conductivities was investigated from the high-resolution 1 H magic-angle-spinning NMR spectra. The protons in EMITFSI molecule exhibit short relaxation times and low activation energies for relaxation, which allow the proton conductivities increase. It was also found that the freezing temperature of EMITFSI decreases to below the normal freezing temperature of pure EMITFSI, which contributes to high conductivities at low temperatures.