Direct Visualization of Li Dendrite Effect on LiCoO2 Cathode by In Situ TEM

In this study, using in situ transmission electron microscopy, the interaction of Li metal with well ‐defined, epitaxial thin films of LiCoO2, the most widely used cathode material, is directly visualized at an atomic scale. It is shown that a spontaneous and prompt chemical reaction is triggered once Li contact is made, leading to expansion and pulverization of LiCoO2 and ending with the final reaction products of Li2O and Co metal. A topotactic phase transition is identified close to the reaction front, resulting in the formation of CoO as a metastable intermediate. Dynamic structural and chemical imaging, in combination with ab initio simulations, reveal that a high density of grain and antiphase boundaries is formed at the reaction front, which are critical for enabling the short ‐range topotactic reactions and long‐range Li propagation. The fundamental insights are of general importance in mitigating Li dendrites related issues and guiding the design principle for more robust energy materials.

Source: Small - November 6, 2018 Category: Nanotechnology Authors: Zhenzhong Yang, Phuong ‐Vu Ong, Yang He, Le Wang, Mark E. Bowden, Wu Xu, Timothy C. Droubay, Chongmin Wang, Peter V. Sushko, Yingge Du Tags: Full Paper Source Type: research