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.