Cooperative transport enabling fast Li-ion diffusion in Thio-LISICON Li10SiP2S12 solid electrolyte
Cooperative transport enabling fast Li-ion diffusion in Thio-LISICON Li10SiP2S12 solid electrolyte
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DOI：
10.1016/j.nanoen.2019.05.085
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发表时间：
2019-08
期刊：
影响因子：
17.6
通讯作者：
Bingkai Zhang;Luyi Yang;Lin-wang Wang;F. Pan
中科院分区：
文献类型：
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作者：
Bingkai Zhang;Luyi Yang;Lin-wang Wang;F. Pan
LISICON类材料作为新型锂离子导体，在全固态锂离子电池中具有潜在的应用前景，正引起人们的关注。虽然以前已经讨论过合作扩散机制的概念，但对这种材料的扩散过程还缺乏详细的了解。在这里，利用先进的模拟技术对基于Li10SiP2S12(LSPs)的体系进行原子尺度的研究为了解其锂离子导电机制提供了有价值的见解。通过分子动力学轨迹分析和势垒计算，我们发现LSP中锂离子的导电是通过间隙锂离子和晶格锂离子的协同运动来实现的。合作迁移的原因是存在一个低势垒步骤，通过这个步骤，一个锂离子的迁移通过互惠的S原子弛豫和静电相互作用帮助相邻的另一个锂离子迁移。协同迁移发生在LiS4四面体通过Li-Li相互作用和双Li位连接形成的通道中。由于更灵活的PS3Cl和较大的Li振荡性，CL掺杂可以通过一种新的低势垒步骤来促进合作迁移，从而平滑了Li势能面，增强了合作迁移。
LISICON-like materials are attracting attention as promising new Li-ion conductors with potential use in all-solid-state Li-ion batteries. Although the concept of cooperative diffusion mechanism has been discussed before, a detail understanding of the diffusion process is still lacking for this material. Here, an atomic-scale investigation of the Li10SiP2S12(LSPS)-based system using advanced simulation techniques provides valuable insights into its Li-ion conducting mechanisms. We find that Li-ion conduction in LSPS occurs through a concerted motion of interstitial and lattice Li-ions, evidenced both from molecular dynamics trajectory analysis and energy barrier calculations. The cause for the cooperative migration is the existence of a low-barrier step, by which one Li-ion's migration helps another adjacent Li-ion's migration through mutually beneficial S atoms relaxation and electrostatic interaction. Cooperative migration occurs in the channels formed by connected LiS4tetrahedrons through Li–Li interaction as well as dual-Li-sites. Cl-doping can enhance cooperative migration by a new low-barrier step due to more flexible PS3Cl and large oscillation of Li, which smoothes Li potential energy surface and enhances cooperative migration.