Effect of Co doping on the properties of Sr0.8Ce0.2MnO3−δ cathode for intermediate-temperature solid-oxide fuel cells

The effect of the Co doping on the structure, electrical conductivity and electrochemical properties of Sr0.8Ce0.2MnO3−δ was investigated. The Co doping decreased the sintering temperature by about 100 °C and cubic structure was synthesized for Sr0.8Ce0.2Mn0.8Co0.2O3−δ. The electrical conductivity of Sr0.8Ce0.2Mn0.8Co0.2O3−δ reached 102 S cm−1 at 700 °C, which was sufficient to provide low ohmic losses at the cathode. In comparison with Sr0.8Ce0.2MnO3−δ, the area-specific resistance of Sr0.8Ce0.2Mn0.8Co0.2O3−δ was 0.10 Ω cm2 at 750 °C, which was about 20 times lower than that of Sr0.8Ce0.2MnO3−δ. While the exchange current density i0 of Sr0.8Ce0.2Mn0.8Co0.2O3−δ was 0.49 A cm−2 at 800 °C, that for Sr0.8Ce0.2MnO3−δ was 0.11 A cm−2. The results show that the Sr0.8Ce0.2Mn0.8Co0.2O3−δ cathode had high catalytic activity for oxygen reduction reaction in the temperature range of 700–800 °C.