Volume 60, Issue 52 pp. 27102-27112
Research Article

Tailoring Co3d and O2p Band Centers to Inhibit Oxygen Escape for Stable 4.6 V LiCoO2 Cathodes

Weijin Kong

Weijin Kong

Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing, 100049 P. R. China

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Jicheng Zhang

Jicheng Zhang

Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing, 100049 P. R. China

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Deniz Wong

Deniz Wong

Helmholtz-Center Berlin for Materials and Energy, Hahn-Meitner-Platz 1, 14109 Berlin, Germany

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Wenyun Yang

Wenyun Yang

State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871 China

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Jinbo Yang

Jinbo Yang

State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871 China

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Christian Schulz

Christian Schulz

Helmholtz-Center Berlin for Materials and Energy, Hahn-Meitner-Platz 1, 14109 Berlin, Germany

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Xiangfeng Liu

Corresponding Author

Xiangfeng Liu

Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing, 100049 P. R. China

CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100190 China

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First published: 19 October 2021
Citations: 172

Graphical Abstract

The escape of surface oxygen and Li-insulator Co3O4 formation are the main causes for the capacity fading of 4.6 V LiCoO2 cathode. The oxygen escape is significantly inhibited by tailoring the Co3d and O2p band centers and enlarging their band gap with MgF2 doping, which enables a stable cycling of 4.6 V LiCoO2 cathode.

Abstract

High-voltage LiCoO2 delivers a high capacity but sharp fading is a critical issue, and the capacity decay mechanism is also poorly understood. Herein, we clarify that the escape of surface oxygen and Li-insulator Co3O4 formation are the main causes for the capacity fading of 4.6 V LiCoO2. We propose the inhibition of the oxygen escape for achieving stable 4.6 V LiCoO2 by tailoring the Co3d and O2p band center and enlarging their band gap with MgF2 doping. This enhances the ionicity of the Co−O bond and the redox activity of Co and improves cation migration reversibility. The inhibition of oxygen escape suppresses the formation of Li-insulator Co3O4 and maintains the surface structure integrity. Mg acts as a pillar, providing a stable and enlarged channel for fast Li+ intercalation/extraction. The modulated LiCoO2 shows almost zero strain and achieves a record capacity retention at 4.6 V: 92 % after 100 cycles at 1C and 86.4 % after 1000 cycles at 5C.

Conflict of interest

The authors declare no conflict of interest.

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