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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

Publication Date

2020-04-28

Online Available Date

2020-04-28

Revised Date

2019-07-08

Received Date

2019-05-23

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