A new oxygen reduction electrocatalyst of barium lanthanide cobaltate for composite cathodes of proton-conducting ceramic fuel cells

This is the first report of the application of the barium lanthanide cobaltate of Ba4Sr2Sm2Co4O15 (BSSC) as an oxygen reduction electrocatalyst of proton-conducting ceramic fuel cells. In this study, composite cathodes of Ba4Sr2Sm2Co4O15-BaCe0.5Pr0.3Y0.2O3-delta (BSSC-BCPY) were developed by varying the mixing ratio. The BSSC-BCPY composite with the optimal composition exhibited a polarization resistance of 0.19 Omega cm(2), 0.31 Omega cm(2), and 0.59 Omega cm(2) at 600 degrees C, 550 degrees C, and 500 degrees C, respectively, for the symmetrical cell test in 3% humidified synthetic air. Its activation energy was evaluated to be 68.5 kJ mol(-1). In this composite system, BSSC appeared to serve as an active phase for the dissociative adsorption of oxygen. The operation of the anode-supported cell employing the optimized cathode was successfully demonstrated at 600 degrees C, and a maximum power density of 197 mW cm(-2) was achieved upon feeding synthetic air and humidified hydrogen to the cathode and anode, respectively. Finally, the chemical stability of the BSSC-BCPY composite in a CO2-containing atmosphere was evaluated.