Adjusting the Redox Coupling Effect via Li/Co Anti-Site Defect for Stable High-Voltage LiCoO2 Cathode

Weijin Kong; Dong Zhou; Qinghua Zhang; Deniz Wong; Ke An; Christian Schulz; Nian Zhang; Jicheng Zhang; Xiangfeng Liu

doi:10.1002/adfm.202211033

Adjusting the Redox Coupling Effect via Li/Co Anti-Site Defect for Stable High-Voltage LiCoO₂ Cathode

Weijin Kong, Dong Zhou, Qinghua Zhang, Deniz Wong, Ke An, Christian Schulz, Nian Zhang, Jicheng Zhang, Xiangfeng Liu

Materials Engineering

Research output: Contribution to journal › Article › peer-review

18 Scopus citations

Abstract

High-voltage LiCoO₂ (LCO) is pressingly required for the portable electronics. But the O→Co charge transfer and the oxygen redox at high delithiation induce the issues of irreversible Co reduction, oxygen release, and unfavored phase transformation. Herein, it is proposed to tune the O→Co charge transfer via regulating Li/Co anti-site defect with Mg²⁺ and (PO₄)³⁻ co-doping to achieve a stable high-voltage LiCoO₂ cathode. The appropriately regulated Li/Co anti-site defect enhances the redox activity of the Co-ions, and inhibits the irreversibility of the oxygen redox and the coupled Co reduction. The increase of the formation energy of oxygen vacancies in the modified cathode at deep delithiation inhibits oxygen escape. Moreover, (PO₄)³⁻ doping also stabilizes oxygen-packed framework due to its strong bond energy with transition metal. These functions enhance the structural stability and the reversible Co/O redox ability. The improved cathode delivers a high capacity and long-cycle capacity retention on both 4.5 and 4.6 V. This study provides some insights into adjusting the redox coupling effect and enhancing the oxygen redox reversibility by Li/Co anti-site regulation.

Original language	English
Article number	2211033
Journal	Advanced Functional Materials
Volume	33
Issue number	8
DOIs	https://doi.org/10.1002/adfm.202211033
State	Published - Feb 16 2023

Funding

This work was supported by National Natural Science Foundation of China (grant no. 11975238, 22005302, and 11575192), the Scientific Instrument Developing Project (grant no. ZDKYYQ20170001), the Strategic Priority Research Program (grant no. XDB28000000), and the International Partnership Program (grant no. 211211KYSB20170060 and 211211KYSB20180020) of the Chinese Academy of Sciences, of the Chinese Academy of Sciences. This work was also supported by the Fundamental Research Funds for the Central Universities, the China Postdoctoral Science Foundation (2020M680648), and Shandong Weiqiao Pioneering Group Company Limited.

Keywords

Li/Co anti-sites
formation energy
high voltage LiCoO
oxygen escape
redox coupling

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1002/adfm.202211033

Cite this

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title = "Adjusting the Redox Coupling Effect via Li/Co Anti-Site Defect for Stable High-Voltage LiCoO2 Cathode",

abstract = "High-voltage LiCoO2 (LCO) is pressingly required for the portable electronics. But the O→Co charge transfer and the oxygen redox at high delithiation induce the issues of irreversible Co reduction, oxygen release, and unfavored phase transformation. Herein, it is proposed to tune the O→Co charge transfer via regulating Li/Co anti-site defect with Mg2+ and (PO4)3− co-doping to achieve a stable high-voltage LiCoO2 cathode. The appropriately regulated Li/Co anti-site defect enhances the redox activity of the Co-ions, and inhibits the irreversibility of the oxygen redox and the coupled Co reduction. The increase of the formation energy of oxygen vacancies in the modified cathode at deep delithiation inhibits oxygen escape. Moreover, (PO4)3− doping also stabilizes oxygen-packed framework due to its strong bond energy with transition metal. These functions enhance the structural stability and the reversible Co/O redox ability. The improved cathode delivers a high capacity and long-cycle capacity retention on both 4.5 and 4.6 V. This study provides some insights into adjusting the redox coupling effect and enhancing the oxygen redox reversibility by Li/Co anti-site regulation.",

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AU - Wong, Deniz

AU - An, Ke

AU - Schulz, Christian

AU - Zhang, Nian

AU - Zhang, Jicheng

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N2 - High-voltage LiCoO2 (LCO) is pressingly required for the portable electronics. But the O→Co charge transfer and the oxygen redox at high delithiation induce the issues of irreversible Co reduction, oxygen release, and unfavored phase transformation. Herein, it is proposed to tune the O→Co charge transfer via regulating Li/Co anti-site defect with Mg2+ and (PO4)3− co-doping to achieve a stable high-voltage LiCoO2 cathode. The appropriately regulated Li/Co anti-site defect enhances the redox activity of the Co-ions, and inhibits the irreversibility of the oxygen redox and the coupled Co reduction. The increase of the formation energy of oxygen vacancies in the modified cathode at deep delithiation inhibits oxygen escape. Moreover, (PO4)3− doping also stabilizes oxygen-packed framework due to its strong bond energy with transition metal. These functions enhance the structural stability and the reversible Co/O redox ability. The improved cathode delivers a high capacity and long-cycle capacity retention on both 4.5 and 4.6 V. This study provides some insights into adjusting the redox coupling effect and enhancing the oxygen redox reversibility by Li/Co anti-site regulation.

AB - High-voltage LiCoO2 (LCO) is pressingly required for the portable electronics. But the O→Co charge transfer and the oxygen redox at high delithiation induce the issues of irreversible Co reduction, oxygen release, and unfavored phase transformation. Herein, it is proposed to tune the O→Co charge transfer via regulating Li/Co anti-site defect with Mg2+ and (PO4)3− co-doping to achieve a stable high-voltage LiCoO2 cathode. The appropriately regulated Li/Co anti-site defect enhances the redox activity of the Co-ions, and inhibits the irreversibility of the oxygen redox and the coupled Co reduction. The increase of the formation energy of oxygen vacancies in the modified cathode at deep delithiation inhibits oxygen escape. Moreover, (PO4)3− doping also stabilizes oxygen-packed framework due to its strong bond energy with transition metal. These functions enhance the structural stability and the reversible Co/O redox ability. The improved cathode delivers a high capacity and long-cycle capacity retention on both 4.5 and 4.6 V. This study provides some insights into adjusting the redox coupling effect and enhancing the oxygen redox reversibility by Li/Co anti-site regulation.

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