Acta Phys. -Chim. Sin. ›› 2021, Vol. 37 ›› Issue (11): 2011007.doi: 10.3866/PKU.WHXB202011007

Special Issue: Energy and Materials Chemistry

• REVIEW • Previous Articles     Next Articles

Localized Surface Doping for Improved Stability of High Energy Cathode Materials

Sidong Zhang1,2, Yuan Liu1,3, Muyao Qi1,2, Anmin Cao1,2,*()   

  1. 1 CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
    2 University of Chinese Academy of Sciences, Beijing 100049, China
    3 Nanozyme Medical Center, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China
  • Received:2020-11-02 Accepted:2020-11-27 Published:2020-12-03
  • Contact: Anmin Cao E-mail:anmin_cao@iccas.ac.cn
  • About author:Anmin Cao, Email: anmin_cao@iccas.ac.cn
  • Supported by:
    the Key Research Program of Frontier Sciences, CAS(ZDBS-LY-SLH020);the Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202010);the National Natural Science Foundation of China(22025507);the National Natural Science Foundation of China(21931012);the Innovation Team for R&D and industrialization of High Energy Density Si-based Power Batteries(2018607219003)

Abstract:

Lithium ion batteries (LIBs) have broad applications in a wide variety of a fields pertaining to energy storage devices. In line with the increasing demand in emerging areas such as long-range electric vehicles and smart grids, there is a continuous effort to achieve high energy by maximizing the reversible capacity of electrode materials, particularly cathode materials. However, in recent years, with the continuous enhancement of battery energy density, safety issues have increasingly attracted the attention of researchers, becoming a non-negligible factor in determining whether the electric vehicle industry has a foothold. The key issue in the development of battery systems with high specific energies is the intrinsic instability of the cathode, with the accompanying question of safety. The failure mechanism and stability of high-specific-capacity cathode materials for the next generation of LIBs, including nickel-rich cathodes, high-voltage spinel cathodes, and lithium-rich layered cathodes, have attracted extensive research attention. Systematic studies related to the intrinsic physical and chemical properties of different cathodes are crucial to elucidate the instability mechanisms of positive active materials. Factors that these studies must address include the stability under extended electrochemical cycles with respect to dissolution of metal ions in LiPF6-based electrolytes due to HF corrosion of the electrode; cation mixing due to the similarity in radius between Li+ and Ni2+; oxygen evolution when the cathode is charged to a high voltage; the origin of cracks generated during repeated charge/discharge processes arising from the anisotropy of the cell parameters; and electrolyte decomposition when traces of water are present. Regulating the surface nanostructure and bulk crystal lattice of electrode materials is an effective way to meet the demand for cathode materials with high energy density and outstanding stability. Surface modification treatment of positive active materials can slow side reactions and the loss of active material, thereby extending the life of the cathode material and improving the safety of the battery. This review is targeted at the failure mechanisms related to the electrochemical cycle, and a synthetic strategy to ameliorate the properties of cathode surface locations, with the electrochemical performance optimized by accurate surface control. From the perspective of the main stability and safety issues of high-energy cathode materials during the electrochemical cycle, a detailed discussion is presented on the current understanding of the mechanism of performance failure. It is crucial to seek out favorable strategies in response to the failures. Considering the surface structure of the cathode in relation to the stability issue, a newly developed protocol, known as surface-localized doping, which can exist in different states to modify the surface properties of high-energy cathodes, is discussed as a means of ensuring significantly improved stability and safety. Finally, we envision the future challenges and possible research directions related to the stability control of next-generation high-energy cathode materials.

Key words: Lithium ion battery, High energy cathode materials, Localized surface doping, Uniform coating, Stability

MSC2000: 

  • O646