Evaluation of A-site Ba-deficient PrBa0.5-xSr0.5Co2O5+δ (x = 0, 0.04 and 0.08) as cathode materials for solid oxide fuel cells

•Ba-deficient PrBa0.5-xSr0.5Co2O5+δ perovskites were studied as IT-SOFC cathode.•Introduction of Ba deficiency promotes the formation of oxygen vacancies.•PB0.5-xSCO oxides have good chemical compatibility with LSGM electrolyte.•Ba deficiency is beneficial to the electrochemical performance of PB0.5-xSCO. Ba-deficient PrBa0.5-xSr0.5Co2O5+δ (PB0.5-xSCO, x = 0, 0.04 and 0.08) perovskites are synthesized. The effects of Ba deficiency on the phase structure, thermal expansion, electrical and electrochemical characteristics of PB0.5-xSCO are investigated. PB0.5-xSCO samples are chemically compatible with LSGM electrolyte at 1000 °С. Slightly decrement of TECs with the rise of Ba deficiency content in PB0.5-xSCO is observed. The introduction of Ba deficiency promotes the formation of additional oxygen vacancies, which is responsible for the decrement of electrical conductivity and improvement of electrochemical performance of PB0.5-xSCO samples. The electrical conductivity is higher than 580 Scm−1 for PB0.5-xSCO perovskites within 50–800 °C. The electrochemical performance is promoted significantly by introducing Ba deficiency in PB0.5-xSCO. The ASRs of the Ba-deficient PB0.5-xSCO decreased by more than 60% in comparison with the sample without Ba-deficiency, indicating the introduction of Ba deficiency is an effective way to improve the electrochemical characteristic of PB0.5-xSCO cathodes.