Electronic and Li-ion diffusion properties in Fe0.875M0.125S2 (M = Ti, V)(001)|Li2S(110) interface by the first-principles study

Abstract

The structure and nature of the interface between the electrode and the discharge product have an important impact on the performance of Lithium‑sulfur (LiS) batteries. We investigated the effects of transition metals Ti and V doped into FeS₂ on the high-rate performance of the interface formed with Li₂S(110). Using the first-principles calculations, we have investigated the interface between FeS₂(001) with doping transition metal Ti and V, and Li₂S(110). The investigation covered aspects such as lattice structure, electrochemical properties, diffusion of Li⁺ at the interface, distribution of charge, and work function. The results indicate that doping with transition metals Ti and V reduces the Li⁺ diffusion barrier. The interfacial density of states introduces metallic properties. Additionally, analysis of work function revealed that Ti doping promotes the establishment of an internal electric field in the interfacial structure which accelerates cycling and migration of Li⁺. This study enhances our understanding of interfacial structure and electrochemical properties between cathode host material and Li₂S.