First-Principles Computational Design and Discovery of Novel Double-Perovskite Proton Conductors

Solid ceramic proton conductors are a crucial component for hydrogen-based energy devices, such as solid oxide fuel cells, electrolyzers, hydrogen separation membranes, and novel electronic computing devices. Perovskite oxide materials in a wide range of cation combinations, especially those with mixed cations, have been developed as solid proton conductors. To rationally guide the future development of these perovskite proton conductors, we perform first-principles computation to systematically investigate a wide range of perovskite and double-perovskite materials and to reveal the effects of different cations and their combinations on proton diffusion and hydrogen incorporation. We observe that lower barrier proton migration can be achieved in perovskites with B-site cations with a lower oxidation state and smaller ionic radii. By studying different mixing of B-site cations, we find that double perovskites with certain B-cations in the layered B-site ordering can simultaneously achieve high proton incorporation and fast proton diffusion without a proton-trapping effect. Our high-throughput computation discovers a number of layered double-perovskite materials with good proton incorporation capability and fast proton diffusion. Our results provide design principles for cation mixing in perovskite proton conductors and provide new research directions for novel double-perovskite proton conductors for novel energy or electronic devices.