Lattice Structures, Electronic Properties and Lithium-ion Transport Dynamics of Li10SnP2S12/Li interface

Abstract

All-solid-state lithium-sulfur batteries (ASSLSBs) are considered one of the most desirable battery technologies thanks to their ultra-high theoretical capacity, low cost, and environmental friendliness. Li10GeP2S12 (LGPS), the existing solid electrolyte with the highest lithium-ion conductivity, is supposed to be replaced by Li10SnP2S12 (LSPS). Current LSPS-related applications and researches focus on structural properties, electrochemical performance, and interface regulation, while such topics as surface properties, interface properties, and the lithium-ion transport mechanism of LSPS interface with metal Li anode are rarely mentioned. Therefore, this paper investigates the interfacial structure, electrical properties, and lithium-ion transport of the LSPS/Li interface using the first-principles calculation method, observing the formation of a interface layer between LSPS and Li, which blocks the conduction of electrons, accelerates the diffusion of lithium-ion, and undermines their surface structures. Ab initio molecular dynamics (AIMD) simulations confirm that the interface benefits Li+ conduction. In addition, S and P in the surface layer of LSPS experience rapid diffusion and eventually penetrate deep into the metal Li anode to dent its integrity, which indicates less active material, disrupted anode surface structure, worse battery performance, and safety issues. This paper may theoretically guide the future application of LSPS in practical engineering.