Insight into the Effects of Cation Disorder and Surface Chemical Residues on the Initial Coulombic Efficiency of Layered Oxide Cathode

Authors

Jin-Li Liu, 1. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, P. R. China;2. China National Quality Supervision Testing Center for Industrial Explosive Materials, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu P.R. China;
Han-Feng Wu, 1. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, P. R. China;3. School of Chemical & Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China;
Zhi-Bei Liu, 1. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, P. R. China;
Ying-Qiang Wu, 1. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, P. R. China;Follow
Li Wang, 1. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, P. R. China;
Feng-Li Bei, 2. China National Quality Supervision Testing Center for Industrial Explosive Materials, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu P.R. China;
Xiang-Ming He, 1. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, P. R. China;Follow

Corresponding Author

Ying-Qiang Wu(yqwu02@tsinghua.edu.cn);
Xiang-Ming He(hexm@mail.tsinghua.edu.cn)

Abstract

Lithium layered oxide LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) is one of the most promising cathode materials in high-energy lithium-ion batteries for electric vehicles. However, one drawback for NCM622 is that its initial coulombic efficiency (ICE) is only about 87%, which is at least 6% lower than that of LiCoO₂ or LiFePO₄. In this work, we investigated the effects of surface chemical residues (e.g., LiOH and Li₂CO₃) and Li/Ni cation disorder resulted during the sintering on the ICE. We found that the ICE of the as-prepared samples could be boosted from 80.80% to 86.68% as the sintering temperatures were increased from 825 to 900 oC. The corresponding Li/Ni cation disorder and surface chemical residues were also reduced with the increasing sintering temperatures. Furthermore, the ICE of the sample sintered at 825 oC could be enhanced by 3.57% after washing with HNO₃ solution to remove the surface residues despite the Li/Ni cation disorder being increased. These results demonstrate that minimizing the amount of surface residuals and the degree of Li/Ni cation disorder through an appropriate sintering process and post-treatment technology is critical to achieve a high ICE and improve the electrochemical performances of NCM622.

Graphical Abstract

Keywords

lithium layered oxide cathode, initial coulombic efficiency, surface chemical residues, Li/Ni cation disorder

DOI Link

https://doi.org/10.13208/j.electrochem.2219001

Publication Date

2022-11-28

Online Available Date

2022-10-31

Revised Date

2022-09-27

Received Date

2022-08-21

Recommended Citation

Jin-Li Liu, Han-Feng Wu, Zhi-Bei Liu, Ying-Qiang Wu, Li Wang, Feng-Li Bei, Xiang-Ming He. Insight into the Effects of Cation Disorder and Surface Chemical Residues on the Initial Coulombic Efficiency of Layered Oxide Cathode[J]. Journal of Electrochemistry, 2022 , 28(11): 2219001.
DOI: 10.13208/j.electrochem.2219001
Available at: https://jelectrochem.xmu.edu.cn/journal/vol28/iss11/8