A stable NH4PO3-glass proton conductor for intermediate temperature fuel cells

A stable and conductive composite material based on NH4PO3 and amorphous oxides (SiO2–P2O5) has been prepared by a wet-chemical route following with firing in ammonia. The composite showed high proton conductivity in both ambient air and humidified 5% H2/Ar. A total conductivity of 6.0–19 mS/cm in the temperature range of 150–250 °C has been achieved. The conductivity (about 19 mS/cm) is stable in humidified 5% H2/Ar during ageing at 175 °C for over 100 h. This material is a potential electrolyte for intermediate temperature fuel cells and other electrochemical devices.