Electrochemical Performance Improvement of Li₂MnO₃ Cathode Materials by MgF₂ Coating

Authors

Du-dan WANG, 1. Light Alloy Research Institute, Central South University, Changsha 410083, Hunan, China;
Fei WANG, 2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China;
Huan-huan ZHAI, 1. Light Alloy Research Institute, Central South University, Changsha 410083, Hunan, China;
Yu-peng LI, 2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China;
Na-chuan YANG, 2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China;
Kang-hua CHEN, 1. Light Alloy Research Institute, Central South University, Changsha 410083, Hunan, China;2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China;Follow

Corresponding Author

Kang-hua CHEN(kanghuachen@csu.edu.cn)

Abstract

Cathode material Li₂MnO₃ has received more and more attention owing to its high theoretical capacity (459 mAh·g ^-1). However, the low initial coulombic efficiency and the poor cycle stability hamper its practical application in lithium-ion batteries. Herein, we investigated the crystal structure and electrochemical performance of Li₂MnO₃ by introducing MgF₂ coating layer. The results indicated that the conversion of partial layer Li₂MnO₃ to spinel phase induced by MgF₂ coating could reduce the initial irreversible capacity and improve the first cycle efficiency. The initial coulombic efficiencies of the 0.5wt.%, 1.0wt.%, and 2.0wt.% MgF₂-coated electrodes were 70.1%, 77.5% and 84.9%, respectively, compared with 57.7% of the pristine cathode. The charge-discharge curves showed that the 1.0wt.% MgF₂-modified Li₂MnO₃ delivered the highest charge and discharge capacities, and exhibited the best cycle stability. The capacity retention rate of the 1.0wt.% MgF₂-coated sample was 81% after the 40th cycles, which was much higher than that of the pristine sample (53.6%). The electrochemical impedance spectroscopic data revealed that the MgF₂ coating reduced the rapid deposition of the resistive component and improved the cycle stability of the electrodes.

Graphical Abstract

Keywords

Li2MnO3 cathode, MgF2 coating, cycle stability, coulombic efficiency

DOI Link

https://doi.org/10.13208/j.electrochem.190524

Publication Date

2020-04-28

Online Available Date

2020-04-28

Revised Date

2019-07-08

Received Date

2019-05-23

Recommended Citation

Du-dan WANG, Fei WANG, Huan-huan ZHAI, Yu-peng LI, Na-chuan YANG, Kang-hua CHEN. Electrochemical Performance Improvement of Li₂MnO₃ Cathode Materials by MgF₂ Coating[J]. Journal of Electrochemistry, 2020 , 26(2): 289-297.
DOI: 10.13208/j.electrochem.190524
Available at: https://jelectrochem.xmu.edu.cn/journal/vol26/iss2/12