Characterization of PrBa0.92CoCuO6−δ as a potential cathode material of intermediate-temperature solid oxide fuel cell

Abstract

PrBa0.92CoCuO6−δ (PB0.92CoCu), a layered perovskite oxide with Ba2+-deficiency at A-site and Cu2+ doping at B-site was synthesized and characterized as cathode material of intermediate-temperature solid oxide fuel cell (IT-SOFC) in comparison with performance of the parent oxide of PrBaCo2O6−δ (PBCoO). PB0.92CoCu had the same phase structure as that of PBCoO but showed a slight lattice expansion. Results of iodometric titration and thermogravimetry (TG) measurements demonstrated that PB0.92CoCu had a higher concentration of oxygen vacancy than PBCoO did. Electrical conductivities of PB0.92CoCu ranged from 255 S cm−1 at 400 °C to 134 S cm−1 at 800 °C in air, meeting the requirement for the cathode of SOFCs. Thermal expansion coefficient (TEC) of PB0.92CoCu was about one quarter decreased compared with TEC of PBCoO. PB0.92CoCu showed improved electrochemical performance than PBCoO characterized by low area specific resistances (ASRs) ranging from 0.12 Ω cm2 at 600 °C to 0.017 Ω cm2 at 750 °C. High peak power densities, 1541 mW cm−2 at 800 °C, 1228 mW cm−2 at 750 °C and 930 mW cm−2 at 700 °C were achieved in a single cell using the PB0.92CoCu cathode. This single cell also showed an operational stability using hydrogen fuel at 650 °C without any decay for 100 h. These results have demonstrated that PB0.92CoCu is a promising cathode material of IT-SOFCs.