Intermediate Temperature Fuel Cell Using CsH₂PO₄/ZrO₂-Based Composite Electrolytes

Proton conductors operating at intermediate temperatures are receiving significant attention due to their advantages over conventionally used materials in proton exchange membrane fuel cells. CsH 2 PO 4 has proven to be proton conducting above 230°C, however within a narrow temperature range of the superprotonic phase. In the present work CsH 2 PO 4 -ZrO 2 composite electrolytes were prepared and investigated in the temperature range from 120°C to 300°C. As a result of improved thermal and mechanical stability the composite electrolyte exhibited high proton conductivities preserved to higher temperatures up to 280°C under low atmospheric humidification. Higher open circuit voltage and stability in the extended temperature range were achieved with composite electrolytes with a CsH 2 PO 4 to ZrO 2 molar ratio of 2.