Protonic ceramic electrochemical cells (PCECs) have received considerable attention owing to their ability to reversibly convert chemical fuels into electricity and vice versa on demand at low temperatures below 600 °C. Unfortunately, the sluggish kinetics at the oxygen electrode induces the poor reaction activity and stability of cells. Hence, the development of a highly active oxygen electrode is greatly needed for the realization of high-performance PCECs. One effective strategy is to bimetal doping high-valence cations in the SrCoO3- 𝛿 lattice to improve the oxygen permeability and stability of the oxygen electrode. However, Sr-containing perovskites still have durability issues related to Sr segregation under water vapor conditions. In this regard, BaCoO3- 𝛿 based perovskite oxides have attracted attention as Sr-free oxygen electrodes for many reasons such as large ionic radii, low electronegativity, and cost-effective of Ba compared to that of Sr. Inspired by recent studies, we present bimetal-doped BaCoO3- 𝛿 based perovskite oxides as a highly active and durable oxygen electrode. The bimetal doping strategy of high valence cations in BaCoO3- 𝛿 lattice can be expected to effectively stabilize the structure to form a cubic perovskite phase as well as a higher oxygen vacancy concentration. Through this work, we showcase the bimetal-doping strategy for BaCoO3- 𝛿 perovskite oxides as an oxygen electrode for high-performance PCECs.
