High-Throughput Discovery of Superionic Conductors Featuring Symmetrically Equivalent Interstitial Sites

Abstract

Superionic conductors exhibit exceptionally high ionic conductivity, making them crucial in next-generation solid-state batteries and solid oxide fuel cells. However, their scarcity remains an obstacle to practical applications, and current discovery strategies are largely guided by chemistry-specific design principles. Here, we observed that the low-temperature phases of a few well-known superionic conductors contain interstitial sites that possess nearly identical local chemical environments to those of lattice sites, which become activated at elevated temperatures and facilitate ion transport. Based on this insight, we proposed a symmetry-based strategy to identify materials containing symmetry-equivalent interstitial sites that satisfy similarity in local chemical environments. By integrating high-throughput screening with molecular dynamics simulations based on a universal machine-learning force field, we identified five, four, and three new oxygen-based, lithium-based, and sodium-based superionic conductors with ionic diffusion properties comparable to leading materials, respectively. Diffusion pathway analysis confirms that these interstitial sites contribute to forming interconnected conduction channels at elevated temperatures. Our work introduces a general design principle and a computationally efficient approach for accelerating the discovery of superionic conductors.