First-principles study on lattice structures and electronic properties of Li1/2La1/2TiO3/Li2S interface

Abstract

The interface structure and electrical properties of solid electrolyte material (Li1/2La1/2TiO3) and positive electrode material (Li2S) in all-solid-state lithium‑sulfur batteries were systematically studied by using the first-principles calculation method based on density functional theory. Li1/2La1/2TiO3/Li2S is a coherent interface with the lattice mismatch of only 3.99%. When the interface distance is 1.890 Å, the interface binding energy is −0.64 J/m2. By analyzing the lattice structures, it is found that the interface expands the transport path of lithium-ion and improves its transport capacity. There is a hybridization of electron orbitals at the interface, which is beneficial to the interface combination. The interface states, the density of states at the interface improve the electrical conductivity and the ion conversion efficiency in the charging and discharging process. The Difference charge and Bader charge at the interface show that there is an obvious charge transfer at the interface. Exchange energy calculation illustrates that the interface can effectively inhibit sulfur passing through the interface and maintains stable chemical stability.