Fabrication of high-performance proton-conducting electrolytes from microwave prepared ultrafine powders for solid oxide fuel cells

The microwave sintering method is found to have advantages over the conventional thermal treatment method for preparing BaZr0.1Ce0.7Y0.2O3-δ powder. Comparing with the conventional thermal treatment, the microwave sintering method allows the solid material to be self-heated, enabling the formation of pure phase BaZr0.1Ce0.7Y0.2O3-δ powder at a relatively low temperature (900 °C) with a short dwell time of 1 h, while the same pure phase can only be formed at 1000 °C in an electric furnace. Importantly, the grain size for the microwave prepared BaZr0.1Ce0.7Y0.2O3-δ powder is much smaller than that of the conventionally thermal treated BaZr0.1Ce0.7Y0.2O3-δ powder. The small powder grain size is found to be beneficial for the densification and grain growth of the resultant electrolyte membrane during the electrolyte sintering procedure. A fuel cell fabricated using this electrolyte membrane with a conductivity of 7 × 10−3 S cm−1 delivers a power output of 791 mW cm−2 at 700 °C.