A new LGPS structure ordering and Li ion dynamics unveiled in Li4GeS4-Li3PS4 superionic conductors-a solid-state NMR study.
A new LGPS structure ordering and Li ion dynamics unveiled in Li4GeS4-Li3PS4 superionic conductors-a solid-state NMR study.
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DOI：
10.1021/acsami.0c03290
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发表时间：
2020-05
影响因子：
9.5
通讯作者：
Xinmiao Liang;Yangming Jiang;Wuyao Cai;Shuaishuai Wu;Liying Wang;Zhenyu Lei;Junfei Chen;Youyi Lei;Li Yang-;Jiwen Feng
中科院分区：
文献类型：
--
作者：
Xinmiao Liang;Yangming Jiang;Wuyao Cai;Shuaishuai Wu;Liying Wang;Zhenyu Lei;Junfei Chen;Youyi Lei;Li Yang-;Jiwen Feng
Li_（10）GeP_（2S）_（12）（LGPS）结构的超导体由于其在晶体中的快速Li离子通道而具有非常高的离子电导率。成分调整有望提高电导率。用~ 7 Li和~（31）P固体核磁共振方法研究了xLi 4GeS 4-yLi 3 PS4（4/1 ≥ x/y ≥ 1/2）系列固溶体的相行为、微观结构和离子动力学。Li_（10）GeP_（2S）_（1/2）（Ge/P = x/y = 1/2）是无序LGPS结构中最小的x/y。随着Ge/P比的增加，室温Li离子电导率先增加，在x/y = 1/1.2时达到最大值，然后减小。同时，无序的LGPS相转变为新的有序的LGPS'相，这与离子电导率的降低是同步的。局域结构的无序有利于快速的离子导电。据此重构了Li_4GeS_4-Li_3PS_4相图。有序LGPS ′和无序LGPS都表现出类似的二维和一维Li扩散路径。但无序LGPS结构有利于快速的离子导电性，其根源在于其快速的二维Li+扩散在ab平面，而不是一维扩散沿着c-轴。在LGPS的结构中观察到两个高温弛豫过程，表明快速和慢速的异质二维跳跃。而LGPS相只有一个均匀的二维跳跃过程。我们的研究结果为理解超离子材料的结构-电导率关系提供了见解，并为优化广泛的固体电解质材料的离子电导率提供了指导。
Superionic conductors of Li10GeP2S12(LGPS) structure presented extraordinary high ionic conductivities attribute to its fast Li ion pathways in crystal. Composition tuning is expected to improve the conductivity. Phase behavior, microstructure and ion dynamics of a series of solid solutions of xLi4GeS4-yLi3PS4 (4/1 ≥ x/y ≥ 1/2) were studied by multiple 7Li and 31P solid-state NMR methods. Li10GeP2S12 (Ge/P = x/y = 1/2) is the smallest x/y of disordered LGPS structure. With the Ge/P ratio rising, room-temperature Li ion conductivity first increases to a maximal at x/y = 1/1.2 and then decreases. Meanwhile, a disordered LGPS phase transforms into a new ordered LGPS' phase synchronously with the reduction in ion conductivity. The disorder of local structure profits fast ionic conductivity. Li4GeS4-Li3PS4 phase diagram was reconstructed accordingly. Both ordered LGPS' and disordered LGPS exhibit similar 2D and 1D Li diffusion paths. But the disordered LGPS structure profits fast ionic conductivity, rooting in its fast 2D Li+ diffusion in ab plane rather than 1D diffusion along c- axis. Two high-temperature relaxation processes are observed in LGPS' structure, suggesting heterogeneous 2D jumps of rapid and slow rates. Whereas only single homogeneous 2D jump process in LGPS phase. Our findings provide insight into understanding the structure-conductivity relationship of superionic materials, and offer guidelines to optimize the ionic conductivity for extensive solid electrolyte materials more than LGPS materials.