Phonon Transport in K₃SbS₄ Solid-State Battery Incorporating an Ion Diffusion Mechanism Using Machine Learning

Understanding the mechanisms behind potassium-ion transport is essential for designing rational strategies for advancing the field of solid-state batteries. Although phonon transport is at play in the exceptionally low thermal conductivity of solid-state batteries, the relationship between ionic transport and thermal properties has remained elusive. Here, we discuss ion diffusion and lattice dynamics in K₃SbS₄ using molecular dynamics simulations powered by a machine-learning interatomic potential with DFT level accuracy. Our analysis reveals that the contribution of coherence terms to thermal conductivity increases substantially because of the liquid-like movement of potassium atoms. Our study provides insight into the intricate atomic dynamics that governs transport in superionic conductors.