Conformal Coating of a High-Voltage Spinel to Stabilize LiCoO2 at 4.6 V

Mingwei Zan; Suting Weng; Haoyi Yang; Junyang Wang; Lufeng Yang; Sichen Jiao; Penghao Chen; Xuefeng Wang; Jie-Nan Zhang; Xiqian Yu; Hong Li

doi:10.1021/acsami.2c21006

Conformal Coating of a High-Voltage Spinel to Stabilize LiCoO₂ at 4.6 V

ACS Appl Mater Interfaces. 2023 Feb 1;15(4):5326-5335. doi: 10.1021/acsami.2c21006. Epub 2023 Jan 23.

Authors

Mingwei Zan^{1

2

3}, Suting Weng^{1

2}, Haoyi Yang^{2

3}, Junyang Wang^{1

2

3}, Lufeng Yang^{1

2

3}, Sichen Jiao^{1

2

3}, Penghao Chen^{1

2}, Xuefeng Wang^{1

2}, Jie-Nan Zhang^{1

3}, Xiqian Yu^{1

2

3}, Hong Li^{1

2

3}

Affiliations

¹ Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
³ Beijing Frontier Research Center on Clean Energy, Huairou Division, Institute of Physics, Chinese Academy of Sciences, Beijing 101400, China.

PMID: 36690409
DOI: 10.1021/acsami.2c21006

Abstract

The ever-growing demand for portable electronic devices has put forward higher requirements on the energy density of layered LiCoO₂ (LCO). The unstable surface structure and side reactions with electrolytes at high voltages (>4.5 V) however hinder its practical applications. Here, considering the high-voltage stability and three-dimensional lithium-ion transport channel of the high-voltage Li-containing spinel (M = Ni and Co) LiM_xMn_2-xO₄, we design a conformal and integral LiNi_xCo_yMn_2-x-yO₄ spinel coating on the surface of LCO via a sol-gel method. The accurate structure of the coating layer is identified to be a spinel solid solution with gradient element distribution, which compactly covers the LCO particle. The coated LCO exhibits significantly improved cycle performance (86% capacity remained after 100 cycles at 0.5C in 3-4.6 V) and rate performance (150 mAh/g at a high rate of 5C). The characterizations of the electrodes from the bulk to surface suggest that the conformal spinel coating acts as a physical barrier to inhibit the side reactions and stabilize the cathode-electrolyte interface (CEI). In addition, the artificially designed spinel coating layer is well preserved on the surface of LCO after prolonged cycling, preventing the formation of an electrochemically inert Co₃O₄ phase and ensuring fast lithium transport kinetics. This work provides a facile and effective method for solving the surface problems of LCO operated at high voltages.

Keywords: high energy density; lithium cobalt oxide; lithium-ion batteries; spinel coating; surface chemistry.