LiAlClS: a low-cost and high-performance solid electrolyte for solid-state batteries.

Solid electrolytes (SEs) are crucial for advancing next-generation rechargeable battery technologies, but their commercial viability is partially limited by expensive precursors, unscalable synthesis, or low ionic conductivity. Lithium tetrahaloaluminates offer an economical option but exhibit low Li conductivities with high activation energy barriers. This study reports the synthesis of lithium aluminum chalcohalide (LiAlClS) using inexpensive precursors one-step mechanochemical milling. The resulting Cl-S mixed-anion sublattice significantly improves the ionic conductivity from 0.008 mS cm for LiAlCl to 0.18 mS cm for LiAlClS at 25 °C. Structural refinement of the high-resolution XRD patterns and Li magic-angle-spinning (MAS) NMR quantitative analysis reveals the formation of tetrahedrally-coordinated, face- and edge-shared LiCl S octahedra that facilitate 3D Li transport. molecular dynamics (AIMD) simulations on LiAlClS support an enhanced 3D network for Li migration with increased diffusivity. All-solid-state battery (ASSB) half-cells using LiAlClS exhibit high-rate and long-term stable cycling performance. This work highlights the potential of LiAlClS as a cost-effective and high-performance SE for ASSBs.