Sodium (translational) and thiophosphate (rotational) dynamics in the plastic crystalline electrolyte Na3PS4

We have recently discovered a high-temperature polymorph of the promising Na-ion conductor, Na3PS4. The new polymorph exhibits plastic crystallinity, with very high sodium (translational) diffusivity and thiophosphate (rotational) diffusivity. These dynamics are expected to be observable by QENS, incoherent for the Na (expected in the 100s of μeV) and coherent for S (expected in the 10s of μeV). Investigating the interplay between anion and cation dynamics, and understanding the how to stabilize such plastic-crystalline ion conductors at lower temperatures would be most impactful in the context of their application as electrolytes for advanced electrochemical devices, in particular batteries.

我们近期发现了一种极具前景的钠离子导体（Na-ion conductor）Na3PS4的高温多晶型物。这种新型多晶型物具有塑性结晶性，同时具备极高的钠（平移）扩散系数与硫代磷酸盐（旋转）扩散系数。这些动力学行为有望通过准弹性中子散射（Quasi-Elastic Neutron Scattering，QENS）观测到：其中钠的信号为非相干散射（预期能量范围为数百微电子伏特），而硫的信号为相干散射（预期能量范围为数十微电子伏特）。研究阴离子与阳离子动力学之间的相互作用，以及探索如何在较低温度下稳定此类塑性结晶离子导体，对于将其应用于先进电化学器件（尤其是电池）的电解质而言，具有至关重要的意义。