Bimetal-Doped BaCoO_3-δ Materials As Oxygen Electrodes for High-Performance Protonic Ceramic Electrochemical Cells

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.