Basic properties of low thermal expansion coefficient (Y0.5Ca0.5)1−xInxBaCo3ZnO7+δ (x=0, 0.1, 0.2, 0.3) solid solutions for solid oxide fuel cell cathode materials

Abstract

• A series of YCI x BCZ cathodes have been studied systematically. • Thermal expansion coefficients of YCI x BCZ are lower than some cobalt-containing cathodes. • The YCI x BCZ cathodes show active catalysis on oxygen reduction reaction. • The YCI 0.2 BCZ cathode displays excellent phase stability and CO 2 tolerance. In this investigation, In-doped (Y 0.5 Ca 0.5 ) 1−x In x BaCo 3 ZnO 7+δ (x=0, 0.1, 0.2, and 0.3, abbreviated as YCI x BCZ) swedenborgite oxides are successfully prepared, and the effects of In-doping on phase structure, electrical conductivity, TEC, thermal stability and electrochemical properties are investigated thoroughly. The partial substitution of In for Y and Ca has a slight effect on the phase structure, electrical conductivity, TEC and area-specific resistance (ASR) of YCI x BCZ. All the YCI x BCZ samples investigated show an excellent tolerance to CO 2 at 800 °C. Additionally, the YCI 0.2 BCZ phase are stable after 72 h exposure to air at 600, 700, and 800 °C, separately, while YCI x BCZ (x=0, 0.1 and 0.3) show instability at 700 °C in air. The optimal composition, YCI 0.2 BCZ, exhibits a relatively low ASR value (0.048 Ω cm 2 at 800°C) and a high power density (345 mW cm −2 at 800°C). The current results demonstrate that YCI 0.2 BCZ is promising cathode material for IT-SOFCs.