Atomistic Assessments of Lithium-Ion Conduction Behavior in Glass–Ceramic Lithium Thiophosphates

We
determined the interatomic potentials of the Li-[PS43–] building block in (Li2S)0.75(P2S5)0.25 (LPS) and predicted the
Li-ion conductivity (σLi) of glass–ceramic
LPS from molecular dynamics. The Li-ion conduction characteristics
in the crystalline/interfacial/glassy structure were decomposed by
considering the structural ordering differences. The superior σLi of the glassy LPS could be attributed to the fact that ∼40%
of its structure consists of the short-ranged cubic S-sublattice instead
of the hexagonally close-packed γ-phase. This glassy LPS has
a σLi of 4.08 × 10–1 mS cm–1, an improvement of ∼100 times relative to
that of the γ-phase, which is in agreement with the experiments.

本研究确定了(Li₂S)₀.₇₅(P₂S₅)₀.₂₅（简称LPS）中Li-[PS₄]³⁻结构基元的原子间势，并通过分子动力学模拟预测了该玻璃陶瓷LPS的锂离子电导率（σ_Li）。研究通过考量结构有序度差异，对晶态、界面及玻璃态结构中的锂离子传导特性进行了分解分析。玻璃态LPS具备优异锂离子电导率的原因可归结为：其约40%的结构由短程立方硫亚晶格构成，而非六方密堆γ相。该玻璃态LPS的锂离子电导率可达4.08×10⁻¹ mS·cm⁻¹，相较于γ相提升约100倍，与实验结果一致。