Theoretical Study on Ion Diffusion Mechanism in W-Doped K₃SbS₄ as Solid-State Electrolyte for K-Ion Batteries

The development of a solid-state electrolyte (SSE) is crucial for overcoming the side reactions of metal potassium anodes and advancing the progress of K-ion batteries (KIBs). Exploring the diffusion mechanism of the K ion in SSE is important for deepening our understanding and promoting its development. In this study, we conducted static calculations and utilized deep potential molecular dynamics (DeepMD) to investigate the behavior of cubic K₃SbS₄. The original K₃SbS₄ exhibited poor ionic conductivity, but we discovered that introducing heterovalent tungsten doping created vacancies, which significantly reduced the activation energy to 0.12 eV and enhanced the ionic conductivity to 1.80 × 10^-2 S/cm. The diffusion of K-ions in K₃SbS₄ primarily occurs through the exchange of positions with K vacancies. This research provides insights into the design of SSE with high ionic conductivity. Furthermore, it highlights the effectiveness of DeepMD as a powerful tool for studying the SSE.