Energy Storage Science and Technology ›› 2020, Vol. 9 ›› Issue (6): 1702-1713.doi: 10.19799/j.cnki.2095-4239.2020.0149

• Energy Storage Materials and Devices • Previous Articles     Next Articles

Synthesis of single-crystal LiNi0.8Co0.1Mn0.1O2 by flux method

Sijia REN1,2(), Leiwu TIAN1,2, Qinjun SHAO1,2, Jian CHEN1()   

  1. 1.Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
    2.University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2020-04-19 Revised:2020-04-27 Online:2020-11-05 Published:2020-10-28
  • Contact: Jian CHEN E-mail:rensijia@dicp.ac.cn;chenjian@dicp.ac.cn

Abstract:

The nickel-rich ternary material LiNi0.8Co0.1Mn0.1O2 (NCM811) is one of the cathode material candidates for new-generation high-energy density lithium-ion batteries due to its advantages of high specific capacity, low cost, and high safety. However, the inter-granular fracture cannot be avoided in polycrystalline NCM811 materials due to the contraction and expansion of the lattice volume during the charge and discharge processes, which causes an unsatisfied cycling life of the materials. Compared to polycrystalline materials, single-crystal materials have better mechanical property and thermal and cycle stabilities. In this work, the LiNO3-LiOH mixed flux with a low-melting point is applied to prepare the single-crystal LiNi0.8Co0.1Mn0.1O2 (NCM811) material. The influence of the synthesis conditions on the structure, morphology, and electrochemical performances of the final products (e.g., flux dosage) and the sintering temperature are systematically investigated through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and electrochemical measurements. The results show that the molar ratio of flux in the mixture of the precursors and the flux is optimized to be 90 mol%, and the optimized sintering temperature is 800 °C. The as-prepared NCM811 material measuring 1-2 μm exhibits an excellent electrochemical performance. Furthermore, the Mg-doped single-crystal NCM 811 material achieves a large discharge specific capacity of 165.4 mA·h/g and a capacity retention of 97.7% after 100 cycles at 1 °C. For comparison, the discharge specific capacity of the polycrystalline NCM811 material synthesized from the commodity precursors is only 132.9 mA·h/g, and the capacity retention is 75.0% after 100 cycles at 1 °C. In conclusion, the electrochemical performance and the cycling capability of the single-crystal NCM811 material are superior to those of the polycrystalline NCM811 material.

Key words: single crystal nickel-rich ternary material, flux method, element doping, lithium-ion batteries

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