Characterization and electrochemical performance of (Ba0.6Sr0.4)1−xLaxCo0.6Fe0.4O3−δ (x = 0, 0.1) cathode for intermediate temperature solid oxide fuel cells

La-doped Ba0.6Sr0.4Co0.6Fe0.4O3−δ perovskites were synthesized and investigated as new cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). The structural characteristics, thermal expansion coefficient (TEC), electrical conductivity and electrochemical properties were characterized by X-ray diffraction (XRD), dilatometry, DC four-terminal method, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The TEC of (Ba0.6Sr0.4)0.9La0.1Co0.4Fe0.6O3−δ (BSLCF) was 14.9 × 10−6 K−1 at 30–800 °C, lower than Ba0.6Sr0.4Co0.4Fe0.6O3−δ (BSCF) of 15.6 × 10−6 K−1. The electrical conductivity of BSCF was improved by La-doping, e.g. a value of 122 S cm−1 for BSLCF vs. 52 S cm−1 for BSCF at 500°C, respectively. In addition, La-doping enhanced the electrochemical activity for oxygen reduction reaction. The polarization resistance of BSLCF was 0.18 Ω cm2 at 700 °C, about a quarter lower than that of BSCF. The improved electrochemical performance of BSLCF should be ascribed to the higher conductivity as well as the improved oxygen adsorption/desorption and oxygen ions diffusion processes.