Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (5): 1604-1615.doi: 10.19799/j.cnki.2095-4239.2023.0072

• Energy Storage Materials and Devices • Previous Articles     Next Articles

Tailoring LiPF6-base electrolyte solvation structure toward a stable Lithium-rich manganese-based cathode interface

Chuan HU1(), Zhiwei HU2, Zhendong LI2, Shuai LI1, Hao WANG1, Liping WANG1()   

  1. 1.University of Electronic Science and Technology, Chengdu 611731, Sichuan, China
    2.Tianmu Lake Institute of Advanced Energy Storage Technologies, Changzhou 213300, Jiangsu, China
  • Received:2023-02-14 Revised:2023-03-12 Online:2023-05-05 Published:2023-05-29
  • Contact: Liping WANG E-mail:2130388134@qq.com;lipingwang@uestc.edu.cn

Abstract:

Li-rich Mn-based cathode has the advantages of high specific capacity and low cost, which is expected to be the cathode material for the next generation of high-energy density Li-metal batteries. However, in practical applications, its charging cutoff voltage is 4.8 V versus Li, leading to the failure of electrolyte oxygenation decompositions, thereby deteriorating the interface between the cathode and electrolyte, making stable battery cycling challenging. A novel high-voltage electrolyte based on LiPF6 is developed, in which 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropylether (TTE) is used as a solvent to promote coordination. The experimental and characterization results show that many Li anions participate in the solvated structure of Li+ coordination after introducing appropriate TTE in the electrolyte, which can form a 5-nm-thick fluorine-rich cathode electrolyte interphase (CEI) on the surface of the cathode, stabilizing its interface and inhibiting the degradation of the cathode layer structure. The Li-rich Mn-based cathode Li-metal battery with the new electrolyte has an 83.9% capacity retention rate after 400 cycles with an average efficiency of 99.8% (0.5 C). The 1.25-Ah Li-rich Mn-based cathode Li-metal battery pouch cell can provide 370 Wh/kg mass-energy density at 0.04 C and still has an 80% capacity retention rate after 45 cycles at 0.08 C, showing a good application prospect. This study is helpful to promote the application of Li-rich Mn-based cathode and provide an experimental basis for the research and development of high energy density Li-metal batteries.

Key words: lithium-rich manganese-based cathode, high voltage, electrolyte solvent, cathode-electrolyte interphase, layered structure, lithium metal pouch cell

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