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A Novel Cathode Material with a Concentration-Gradient for High-Energy and Safe Lithium-Ion Batteries

Authors

  • Yang-Kook Sun,

    Corresponding author
    1. Department of Chemical Engineering Hanyang University Seoul 133-791(Republic of Korea)
    • Department of Chemical Engineering Hanyang University Seoul 133-791(Republic of Korea).
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  • Dong-Hui Kim,

    1. Department of Chemical Engineering Hanyang University Seoul 133-791(Republic of Korea)
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  • Chong Seung Yoon,

    1. Department of Materials Science and Engineering Hanyang University Seoul 133-791(Republic of Korea)
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  • Seung-Taek Myung,

    1. Department of Chemical Engineering Iwate University 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan)
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  • Jai Prakash,

    1. Department of Chemical and Biological Engineering Illinois Institute of Technology 10 W. 33rd Street, Chicago, IL (USA)
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  • Khalil Amine

    Corresponding author
    1. Electrochemical Technology Program Chemical Sciences and Engineering Division Argonne National Laboratory 9700 South Cass Avenue, Argonne, IL 60439 (USA)
    • Electrochemical Technology Program Chemical Sciences and Engineering Division Argonne National Laboratory 9700 South Cass Avenue, Argonne, IL 60439 (USA).
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Abstract

A high-energy functional cathode material with an average composition of Li[Ni0.72Co0.18Mn0.10]O2, mainly comprising a core material Li[Ni0.8Co0.2]O2 encapsulated completely within a stable manganese-rich concentration-gradient shell is successfully synthesized by a co-precipitation process. The Li[Ni0.72Co0.18Mn0.10]O2 with a concentration-gradient shell has a shell thickness of about 1 µm and an outer shell composition rich in manganese, Li[Ni0.55Co0.15Mn0.30]O2. The core material can deliver a very high capacity of over 200 mA h g−1, while the manganese-rich concentration-gradient shell improves the cycling and thermal stability of the material. These improvements are caused by a gradual and continuous increase of the stable tetravalent Mn in the concentration-gradient shell layer. The electrochemical and thermal properties of this cathode material are found to be far superior to those of the core Li[Ni0.8Co0.2]O2 material alone. Electron microscopy also reveals that the original crystal structure of this material remains intact after cycling.

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