Conductivity and electrochemical performance of (Ba0.5Sr0.5)0.8La0.2CoO3−δ cathode for intermediate-temperature solid oxide fuel cell

This study reports the successful preparation of a single-phase cubic (Ba0.5Sr0.5)0.8La0.2CoO3−δ perovskite by the citrate-EDTA complexing method. Its crystal structure, thermogravimetry, coefficient of thermal expansion, electric conductivity, and electrochemical performance were investigated to determine its suitability as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Its coefficient of thermal expansion shows abnormal expansion at 300 °C, which is associated with the loss of lattice oxygen. The maximum conductivity of a (Ba0.5Sr0.5)0.8La0.2CoO3−δ electrode is 689 S/cm at 300 °C. Above 300 °C, the electronic conductivity of (Ba0.5Sr0.5)0.8La0.2CoO3−δ decreases due to the formation of oxygen vacancies. The charge-transfer resistance and gas phase diffusion resistance of a (Ba0.5Sr0.5)0.8La0.2CoO3−δ-Ce0.8Sm0.2O1.9 composite cathode are 0.045 Ω cm2 and 0.28 Ω cm2, respectively, at 750 °C.