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Achieving Stable Cycling of LiCoO 2 at 4.6 V by Multilayer Surface Modification
Author(s) -
Cheng Tao,
Ma Zhongtao,
Qian Ruicheng,
Wang Yeting,
Cheng Qin,
Lyu Yingchun,
Nie Anmin,
Guo Bingkun
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202001974
Subject(s) - materials science , surface modification , electrolyte , cathode , coating , chemical engineering , layer (electronics) , doping , nanotechnology , electrode , optoelectronics , electrical engineering , chemistry , engineering
LiCoO 2 , which was first proposed as a cathode in 1980 by Prof. John B. Goodenough, is still one of the most popular commercial cathodes for lithium‐ion batteries. Tremendous efforts have been invested in increasing the capacity of LiCoO 2 by charging to high voltage. However, a series of issues, such as structural instability and dramatic side reactions with electrolytes, can emerge as cut‐off voltage above 4.5 V (vs Li/Li + ). Here, a surface modification strategy with a multilayer structure is provided, involving a Zn‐rich surface coating layer, rock‐salt phase buffer layer and surface gradient Al doping layer, to overcome the detrimental issues and achieve stable cycling of LiCoO 2 at 4.6 V. The complete coating of the modification layer restrains the interfacial side reactions with electrolyte and inhibits the impedance growth. The phenomenon of quasi‐epitaxial growth demonstrates that the multilayer structure significantly reduces the lattice mismatch between host LiCoO 2 and surface coating layer and enhances the stability of the Zn‐rich outside layer, which promote the long‐term effectiveness of the modification. Furthermore, the disordered rock‐salt phase layer and Al surface doping also enhance the structural stability. All of these synergistically lead to the stable cycling of LiCoO 2 at 4.6 V with a capacity retention of 65.7% after 500 cycles.