Li_9.9SnP₂S_11.8Cl_0.1O_0.1: A Novel Sulfide Solid-State Electrolyte with High Ionic Conductivity and Air Stability

The high ionic conductivity and favorable mechanical properties of sulfide solid-state electrolytes have attracted extensive research attention in the field of all-solid-state lithium batteries. However, these materials encounter obstacles related to inadequate air stability and limited compatibility with lithium metal. This study prepared a Cl and O-codoped Li10SnP2S12-type solid-state electrolyte, where the ionic conductivity exhibited a notable enhancement, rising from 1.58 to 2.94 mS cm–1. The introduction of Cl can introduce Li vacancies, while codoping Cl and O can introduce an S–Cl–O mixed anion framework, reducing the electrostatic attraction to Li and enlarging the lattice volume. Density functional theory calculations show that the synergistic modulation of Cl and O can reduce the lithium diffusion barrier and provide effective diffusion space. Consequently, this facilitates a heightened rate of lithium-ion migration, thus elucidating the observed enhancement in ionic conductivity. After doping, the electrolyte demonstrates enhanced air stability and compatibility with lithium metal. The all-solid-state battery using Li9.9SnP2S11.8Cl0.1O0.1 as the electrolyte shows higher initial discharge specific capacity and good cycling stability.