Multivalent metal perovskite YbCoO₃ as a novel proton-conducting electrolyte for solid oxide fuel cells

For solid oxide fuel cells, an electrolyte with good stability and high ion conductivity is highly desired but difficult to obtain. Recently, a novel hydrogenation mechanism other than water dissociation have been reported in multivalent metal-based oxides, which provide a new route to increase proton concentration as well as proton conductivity. In this computational study, we propose the multivalent metal perovskite YbCoO₃ as a promising proton-conducting electrolyte due to its good thermodynamic and chemical stability, semiconductor characteristics, high-concentration proton incorporation, and low proton migration barrier. Our findings also reveal that charge compensation of the multivalent metal is crucial for the high-concentration proton incorporation. On the other hand, both the shortening of the O-O distance and the Co-H repulsion play key roles in determining the energy barrier to proton migration, where local structural deformations are responsible for facilitating intra- and inter-octahedron proton transfer in YbCoO₃. Our results might assist in the development of high-performance proton-conducting electrolytes for advanced solid oxide fuel cells.