Cl-Doped Cubic K₃SbS₄ as a Solid-State Electrolyte for K-Ion Batteries with Ultrafast Ionic Conductivity

Developing high-performance solid-state electrolytes (SSEs) is of great significance for addressing the foundational scientific issues of K-ion batteries and accelerating their transition to practical applications. The complex experimental explorations are time-consuming and labor-intensive, and the technical barriers in phase synthesis have hindered the development speed of potassium SSEs. In this study, we studied the effect of Cl-doping on the K-ion diffusion rate of K3SbS4 via deep molecular dynamics. To reduce the quantum fluctuation phenomena during the simulation process, we simulated a system composed of approximately 3400 atoms for 500 ps and averaged the results over five runs. The results of the MD simulation show that Cl doping can induce the generation of potassium vacancies, and a small amount of doping can convert K3SbS4 from an ionic insulator to a superionic conductor with an ionic conductivity of 14.8 mS/cm at 300 K. The cubic K3–xSbS4–xClx is a promising candidate for potassium SSEs for K-ions.