Proton conduction of MO-P2O5 glasses (M = Zn, Ba) containing a large amount of water

•Zinc phosphate glasses melted at 800 °C contained a large amount of water.•Proton conductivity was measured to be 1 × 10−3 S/cm at 250 °C.•Maximum power density was 1.2 mW/cm2 at 200 °C for a fuel cell with zinc phosphate.

Zinc and barium phosphate glasses show good proton conductivity at intermediate temperature around 200 °C. Infrared spectra and 1H magic angle spinning-nuclear magnetic resonance (MAS–NMR) spectra proposed that a 30 mol%ZnO-70 mol%P2O5 glass melted at 800 °C has a large amount of ‘mobile’ protons. The proton conductivity at 250 °C was measured to be 1 × 10−3 S/cm. A H2-air fuel cell using the ZnO–P2O5 glass electrolyte of 1.8 mm in thickness showed the maximum power density of 1.2 mW/cm2 at 200 °C.

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