Antimony-doped strontium cobalt oxide as promising cathode for low-temperature solid oxide fuel cell with excellent carbon dioxide tolerance

[Display omitted] •Antimony doping stabilizes cubic perovskite structure of SrCoO3-δ.•Remarkable oxygen reduction reaction activity is achieved.•The charge-transfer is confirmed as the rate-determining step.•Antimony doping enables perfect performance recovering from CO2 erosion.•The CO2 tolerance mechanism is revealed via experimental computational results. The cathode destruction by CO2 erosion has emerged as great obstacle to solid oxide fuel cells (SOFCs) application. In this work, replacing 18.75 % cobalt with antimony in SrCoO3-δ demonstrates substantial improvements in CO2 tolerance and perfect performance recovering from 10 vol% CO2 is achieved with symmetrical and single cell test. Both experimental and computational results prove the weakened CO2 adsorption strength. In addition, outstanding oxygen transport properties is obtained with chemical oxygen surface exchange coefficient of 1.97 × 10−3 cm s-1 at 600 °C, two orders of magnitude higher than the state-of-art cathode material La0.6Sr0.4Co0.2Fe0.8O3-δ. The single phase electrode shows brilliant oxygen reduction reaction activity with electrode resistance of 0.185 Ω cm2 at 600 °C, which is attributed to the accelerated charge transfer rate and augmented adsorbed oxygen species. The combination of exceptional electrochemical activity and excellent CO2 tolerance demonstrates its significant advantage for practical applications as promising cathode for low-temperature SOFCs.