Crystal Structural Framework of Lithium Super-Ionic Conductors

摘要

As technologically important materials for solid-state batteries, Li super-ionic conductors are a class of materials exhibiting exceptionally high ionic conductivity at room temperature. These materials have unique crystal structural frameworks hosting a highly conductive Li sublattice. However, it is not understood why certain crystal structures of the super-ionic conductors lead to high conductivity in the Li sublattice. In this study, using topological analysis and ab initio molecular dynamics simulations, the crystal structures of all Li-conducting oxides and sulfides are studied systematically and the key features pertaining to fast-ion conduction are quantified. In particular, a unique feature of enlarged Li sites caused by large local spaces in the crystal structural framework is identified, promoting fast conduction in the Li-ion sublattice. Based on these quantified features, the high-throughput screening identifies many new structures as fast Li-ion conductors, which are further confirmed by ab initio molecular dynamics simulations. This study provides new insights and a systematic quantitative understanding of the crystal structural frameworks of fast ion-conductor materials and motivates future experimental and computational studies on new fast-ion conductors.