Cl-Doped Li₁₀SnP₂S₁₂ with Enhanced Ionic Conductivity and Lower Li-Ion Migration Barrier

All-solid-state lithium batteries based on sulfide solid electrolytes have attracted much attention because of their high ionic conductivity. Li10SnP2S12 (LSPS) has the same structure as Li10GeP2S12, and there is little difference in ionic conductivity between them, but the preparation cost of LSPS is lower. Here, Cl doping is used to improve the electrochemical stability of the LSPS to the anode and the Li-ion transport performance. Among them, Li9.9SnP2S11.9Cl0.1 had a high ion conductivity of 2.62 mS cm–1 after cold pressure. On the crystal structure, X-ray diffraction Rietveld refinement indicated that the Cl-substituted portion S is successfully incorporated into the lattice of the LSPS, increasing Li-ion vacancies and reducing the distance between adjacent Li-ion distributed along the c-axis, these are conducive to Li-ion transmission. The temperature-dependent AC impedance experiment and density functional theory calculation show that doping with Cl makes Li9.9SnP2S11.9Cl0.1 have a lower activation energy. The assembled lithium symmetric batteries show that the doping of Cl promotes the stability of the interface between LSPS and the lithium metal anode. The charge–discharge tests of all-solid-state batteries using Li9.9SnP2S11.9Cl0.1 as electrolyte have confirmed that Cl doping can improve the electrochemical performance of LSPS, which have a higher specific capacity and cycle life.