Handy Joseph V, Luo Yuting, Andrews Justin L, Bhuvanesh Nattamai, Banerjee Sarbajit
Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA.
Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA.
Angew Chem Int Ed Engl. 2020 Sep 14;59(38):16385-16392. doi: 10.1002/anie.202005513. Epub 2020 Jul 21.
The diffusion pathways of Li-ions as they traverse cathode structures in the course of insertion reactions underpin many questions fundamental to the functionality of Li-ion batteries. Much current knowledge derives from computational models or the imaging of lithiation behavior at larger length scales; however, it remains difficult to experimentally image Li-ion diffusion at the atomistic level. Here, by using topochemical Li-ion insertion and extraction to induce single-crystal-to-single-crystal transformations in a tunnel-structured V O polymorph, coupled with operando powder X-ray diffraction, we leverage single-crystal X-ray diffraction to identify the sequence of lattice interstitial sites preferred by Li-ions to high depths of discharge, and use electron density maps to create a snapshot of ion diffusion in a metastable phase. Our methods enable the atomistic imaging of Li-ions in this cathode material in kinetic states and provide an experimentally validated angstrom-level 3D picture of atomic pathways thus far only conjectured through DFT calculations.
锂离子在嵌入反应过程中穿过阴极结构时的扩散路径，是锂离子电池功能许多基本问题的基础。目前的许多知识来自计算模型或更大长度尺度下锂化行为的成像；然而，在原子水平上通过实验成像锂离子扩散仍然很困难。在这里，通过使用拓扑化学锂离子嵌入和脱嵌来诱导隧道结构V O多晶型物中的单晶到单晶转变，并结合原位粉末X射线衍射，我们利用单晶X射线衍射来确定锂离子在高放电深度时优先占据的晶格间隙位置序列，并使用电子密度图来创建亚稳相中离子扩散的快照。我们的方法能够对这种阴极材料中处于动力学状态的锂离子进行原子水平成像，并提供一个经过实验验证的埃级三维原子路径图，迄今为止，该图仅通过密度泛函理论（DFT）计算推测得出。
