Crystallization Mechanism of β-Li ₃ PS ₄ Solid Electrolyte

The crystallization of solid-state electrolytes is crucial for their ionic transport and practical applicability in all-solid-state batteries. β-Li3PS4 is a key thiophosphate electrolyte, yet its crystallization mechanism remains unclear. Using machine-learning molecular dynamics simulations with enhanced sampling, we reveal atomistic crystallization pathways of β-Li3PS4 from amorphous and liquid states. We evaluate nucleation free-energy barriers, assess the relevance of classical nucleation theory, and predict crystallization pathways using classification-based machine learning. Our results reveal that local ordering of PS4 tetrahedra is the key precursor for β-Li3PS4 nucleation, while the rearrangement ability of P within PS4 tetrahedra predicts the sequence of structural transformations.