Investigating barium cobaltite system to discover highly active and robust oxygen reduction reaction catalyst in solid oxide fuel cells

Abstract

Solid oxide fuel cells (SOFCs) has garnered attention as energy conversion devices with high efficiency and eco-friendliness. However, high working temperature causes rapid degradation of performance and consumption of substantial energy and time to operate the device. Accordingly, a lot research has been devoted to lowering the operation temperature. However, due to the increasing resistance of the device with decreasing temperature, the performance of the SOFCs is significantly degraded. In order to address the problem, novel electrocatalyst toward oxygen reduction reaction (ORR), which is known to be notoriously sluggish, is presented in this research. Among the various material groups, BaCoO$_{3-δ}$ (BCO) perovskite system has attracted scant attention due to the unstable crystal structure. However, cubic BCO brings about distinct characteristic compared with the other material, such as cheap price of barium and high concentrations of oxygen vacancies. For this reason, revisiting the BCO system again, we tried to figure out the relationship between crystal structure and ORR activity. Finally, through the electrochemical evaluation with single cell employing the best material among the candidates, it was proved that high-performance and high durable SOFC can be feasible by BCO cathodes.