First-Principles Design of Highly Functional Sulfide Electrolyte of Li_{10 -x}SnP₂S_{12- x}Cl_x for All Solid-State Li-Ion Battery Applications

Using first-principles density functional theory calculations and ab initio molecular dynamic simulations, we propose Li_10-xSnP₂S_12-xCl_x 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 S^2- 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 Li_10-xSnP₂S_12-xCl_x 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 Li_10-xSnP₂S_12-xCl_x as a promising electrolyte material to facilitate a wide commercialization of all solid-state Li ion batteries.