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

Abstract La-doped Ba 0.6 Sr 0.4 Co 0.6 Fe 0.4 O 3− 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 (Ba 0.6 Sr 0.4 ) 0.9 La 0.1 Co 0.4 Fe 0.6 O 3− δ (BSLCF) was 14.9 × 10 −6 K −1 at 30–800 °C, lower than Ba 0.6 Sr 0.4 Co 0.4 Fe 0.6 O 3− 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 cm 2 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.