First-Principles Computational Design and Discovery of Solid-Oxide Proton Conductors

Solid-oxide proton-conducting materials
are key components for
hydrogen-based energy devices, including solid-oxide fuel cells, electrolyzers,
hydrogen separation membranes, and novel electronic computing devices.
The further development of these devices requires proton-conducting
materials with high proton conductivity and good stability with hydrogen
and water under the device-operating environment. In this study, we
perform a systematic first-principles computational study on a wide
range of ternary oxide materials to identify new proton conductor
materials and to understand the role of both cations and compositions
on material stability and proton conductivity. By analyzing the computational
results of over 5000 oxide materials, we reveal how the cation species and mole fraction affect
water stability and hydrogen insertion capability. By studying proton
diffusion in many different materials, our analyses show that oxide
materials with connected BO6 octahedra are optimal for
fast proton diffusion. Following the understanding, a high-throughput
computation identifies a dozen oxide materials with good water stability,
good proton incorporation capability, and fast proton diffusion. This
study provides fundamental understanding and design principles to
develop oxide materials with fast proton diffusion and good stability.