Investigation of Ba1−xSrxCo0.8Fe0.2O3−δ as cathodes for low-temperature solid oxide fuel cells both in the absence and presence of CO2

Ba1−xSrxCo0.8Fe0.2O3−δ (BSCF)(0 ≤ x ≤ 1) composite oxides were prepared and tested as cathodes for low-temperature solid oxide fuel cells (SOFCs) both in the absence and presence of CO2. It is found that the BSCF cathodes in the whole range of strontium doping levels show promising performance at 500–600 °C in the absence of CO2, among which the SrCo0.8Fe0.2O3−δ (SCF) cathode gives the highest power density while BaCo0.8Fe0.2O3−δ (BCF) cathode shows the lowest performance. The impedance analysis reveals that both the ohmic resistance and polarization resistance of the fuel cell increases when the strontium content decreases. It is believed that the microstructure and electrical conductivity simultaneously affect the process of oxygen reduction. The presence of CO2 deteriorates the BSCF performance by adsorbing on the cathode surface and thus obstructing the oxygen surface exchange reaction. The CO2 exerts a more intense influence on BSCF with higher barium content.