Structural Insights and 3D Diffusion Pathways within the Lithium Superionic Conductor Li10GeP2S12

Inspired by the ongoing debate about the ion dynamics in the lithium superionic conductor Li10GeP2S12 (LGPS), we present neutron powder diffraction data in combination with analyses of differential bond valence and nuclear density maps to elucidate the underlying diffusion pathways in Li10GeP2S12. LGPS exhibits quasi-isotropic three-dimensional lithium diffusion pathways, which is a combination of one-dimensional diffusion channels crossing two diffusion planes. Furthermore, ultrasonic speeds of sound measurements are used to understand the lattice dynamics and obtain the Debye temperature of LGPS. Temperature dependent X-ray diffraction is performed in order to understand the local temperature-dependent behavior of the prevalent structural backbone, as well as the thermal stability of the material. At elevated temperatures, the superionic conducting Li10GeP2S12 phase partially decomposes into Li4P2S6, explaining the deterioration of the ionic conductivity upon heating.

受锂超离子导体Li₁₀GeP₂S₁₂（LGPS）中离子动力学相关持续学术争论的启发，本研究结合中子粉末衍射（neutron powder diffraction）数据与差分键价、核密度图分析，阐明了Li₁₀GeP₂S₁₂内在的锂扩散路径。LGPS具备准各向同性的三维锂扩散通道，该通道由交叉于两个扩散平面的一维扩散通道组合而成。此外，本研究通过超声声速测量（ultrasonic speeds of sound measurements）表征晶格动力学，并获取了LGPS的德拜温度（Debye temperature）。为解析主流结构骨架的温度依赖局部行为，同时明确该材料的热稳定性，本研究开展了变温X射线衍射（temperature dependent X-ray diffraction）实验。在高温环境下，超离子导电相Li₁₀GeP₂S₁₂会部分分解为Li₄P₂S₆，这一现象解释了升温过程中离子电导率衰减的原因。