Solid-state electrolytes with high ionic conductivity will be crucial for future energy storage systems. Among many possible materials, thiophosphates offer both favourable mechanical properties and fast ionic transport. β-Li₃PS₄, as a member of the thiophosphate family, has gained recent attention, due to its remarkable increase in Li⁺ ionic conductivity when prepared via solvent-assisted synthesis. Despite earlier studies, the lithium ion migration processes causing the increased conductivity remain, however, still uncertain. Here, we study both long-range cation transport and local Li⁺ jump processes by broadband impedance spectroscopy and nuclear magnetic resonance (NMR), respectively. In particular, we focus on the comparison between mechanochemical and solvent-assisted synthesis to determine the origin of the increased ionic conductivity observed in the latter. Our measurements reproduce the previously reported high ionic conductivity and reveal that synthesis conditions significantly affect the Arrhenius pre-exponential factor governing ionic conductivity. Diffusion-controlled ⁷Li (and ³¹P) NMR spin relaxation rates confirm rapid, anisotropic lithium ion hopping that is characterized by timescale-dependent activation energies E_a ranging from 0.40 eV (long-range transport, as also seen by conductivity spectroscopy) to values down to 0.09 eV (local barriers).

中文翻译：

---

溶剂辅助合成制备的 X 射线非晶和结晶 Li3PS4 中形态依赖性的 Li+ 离子动力学


具有高离子电导率的固态电解质对于未来的储能系统至关重要。在许多可能的材料中，硫代磷酸盐具有良好的机械性能和快速的离子传输。β-Li₃PS₄ 作为硫代磷酸盐家族的一员，由于通过溶剂辅助合成制备时 Li⁺ 离子电导率的显著增加，最近受到了关注。尽管进行了早期研究，但导致电导率增加的锂离子迁移过程仍然不确定。在这里，我们分别通过宽带阻抗谱和核磁共振 （NMR） 研究了长程阳离子传输和局部 Li⁺ 跳跃过程。特别是，我们关注机械化学和溶剂辅助合成之间的比较，以确定在后者中观察到的离子电导率增加的来源。我们的测量再现了先前报道的高离子电导率，并揭示了合成条件显着影响控制离子电导率的 Arrhenius 指数前因子。扩散控制的 ⁷Li（和 ³¹P）NMR 自旋弛豫速率证实了快速、各向异性的锂离子跳跃，其特征是依赖于时间尺度的活化能 E_a，范围从 0.40 eV（长距离传输，也可通过电导波谱看到）到低至 0.09 eV（局部势垒）的值。