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Title: Direct Visualization of Li Dendrite Effect on LiCoO 2 Cathode by In Situ TEM

Abstract

Li dendrites are known to cause deterious, and in many cases catastrophic, effect on the performance of Li rechargeable batteries. However, the mechanistic failure mechanism of cathodes upon in contact with Li metal is far from clear. In this study, using in situ transmission electron microscopy, we directly visualize at an atomic scale the interaction of Li dendrites with well-defined, epitaxial thin films of LiCoO2, the most widely used cathode material. We show that a spontaneous and prompt chemical reaction is trigged once the Li contact is made, leading to expansion and amorphization of the LiCoO2 structure, with Li2O and Co metal being the final reaction products. 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 inito simulations reveal that a high density of antiphase grain boundaries are 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.

Authors:
ORCiD logo [1];  [1];  [2];  [1];  [2];  [3];  [1];  [2];  [1];  [1]
  1. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA
  2. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA
  3. Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1501615
Report Number(s):
PNNL-SA-135382
Journal ID: ISSN 1613-6810
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Small
Additional Journal Information:
Journal Volume: 14; Journal Issue: 52; Journal ID: ISSN 1613-6810
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
In situ transmission electron microscopy (TEM), LiCoO2, STEM, Lithium dendrite, Phase transition

Citation Formats

Yang, Zhenzhong, Ong, Phuong-Vu, He, Yang, Wang, Le, Bowden, Mark E., Xu, Wu, Droubay, Timothy C., Wang, Chongmin, Sushko, Peter V., and Du, Yingge. Direct Visualization of Li Dendrite Effect on LiCoO 2 Cathode by In Situ TEM. United States: N. p., 2018. Web. doi:10.1002/smll.201803108.
Yang, Zhenzhong, Ong, Phuong-Vu, He, Yang, Wang, Le, Bowden, Mark E., Xu, Wu, Droubay, Timothy C., Wang, Chongmin, Sushko, Peter V., & Du, Yingge. Direct Visualization of Li Dendrite Effect on LiCoO 2 Cathode by In Situ TEM. United States. doi:10.1002/smll.201803108.
Yang, Zhenzhong, Ong, Phuong-Vu, He, Yang, Wang, Le, Bowden, Mark E., Xu, Wu, Droubay, Timothy C., Wang, Chongmin, Sushko, Peter V., and Du, Yingge. Tue . "Direct Visualization of Li Dendrite Effect on LiCoO 2 Cathode by In Situ TEM". United States. doi:10.1002/smll.201803108.
@article{osti_1501615,
title = {Direct Visualization of Li Dendrite Effect on LiCoO 2 Cathode by In Situ TEM},
author = {Yang, Zhenzhong and Ong, Phuong-Vu and He, Yang and Wang, Le and Bowden, Mark E. and Xu, Wu and Droubay, Timothy C. and Wang, Chongmin and Sushko, Peter V. and Du, Yingge},
abstractNote = {Li dendrites are known to cause deterious, and in many cases catastrophic, effect on the performance of Li rechargeable batteries. However, the mechanistic failure mechanism of cathodes upon in contact with Li metal is far from clear. In this study, using in situ transmission electron microscopy, we directly visualize at an atomic scale the interaction of Li dendrites with well-defined, epitaxial thin films of LiCoO2, the most widely used cathode material. We show that a spontaneous and prompt chemical reaction is trigged once the Li contact is made, leading to expansion and amorphization of the LiCoO2 structure, with Li2O and Co metal being the final reaction products. 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 inito simulations reveal that a high density of antiphase grain boundaries are 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.},
doi = {10.1002/smll.201803108},
journal = {Small},
issn = {1613-6810},
number = 52,
volume = 14,
place = {United States},
year = {2018},
month = {11}
}