Characteristics of YCoO₃-type perovskite oxide and application as an SOFC cathode

YCoO₃is discussed as a novel cathode material for solid oxide fuel cells (SOFCs). One of the major issues for SOFC development is the side reactions that occur at the electrode and electrolyte interfaces. Characteristics such as the phase stability, reactivity against YSZ, electrical conductivity, and thermal expansion coefficients (TECs) of YCoO₃were investigated. YCoO₃was produced by the sol-gel method below 975 °C, and the fewest impurities were observed at a Y molar ratio of 0.96 (YCO-096). YCO-096 did not react significantly with the YSZ electrolyte when fired at 975 °C for 1 h. The main charge carrier of YCO-096 was confirmed to be electron-holes, h⁺, and the maximum conductivity was estimated to be 700 S cm⁻¹at 900 °C. The TECs of YCO-096 were in the range of 16.5-44.2 × 10⁻⁶°C⁻¹from room temperature to 900 °C. The YCO-096 cathode was stable in the YSZ electrolyte SOFC. Oxygen defects formed at the surfaces of particle YCO-096 were considered to significantly improve the cathodic performance.