First-Principles Design of Highly Functional Sulfide Electrolyte of Li_{10<i>−x</i>}SnP₂S_{12−<i>x</i>}Cl_<i>x</i> for All Solid-State Li-Ion Battery Applications

Abstract

Using first-principles density functional theory calculations and ab initio molecular dynamic simulations, we propose Li10-xSnP2S12-xClx as a highly functional solid electrolyte for a Li ion battery. The underlying mechanisms of excellent Li ion conductivity and electrochemical stability are 2-fold: (i) complete replacement of expensive Ge4+ with relatively cheaper Sn4+ species and (ii) partial substitution of Cl– for S2– to form body-centered cubic anionic framework. The rationally controlled doping levels of the halide Cl atoms play a vital role to enlarge Li ion diffusion channel sizes. The unique feature of the electronic structure in Li10-xSnP2S12-xClx ensures its superior electrochemical durability in comparison to the conventional LGPS counterpart. We propose a design principle to crank up the stability even more, as high as 8 V, via forming passivating Li–Cl layers at the Li-metal anode surface. We propose Li10-xSnP2S12-xClx as a promising electrolyte material to facilitate a wide commercialization of all solid-state Li ion batteries.