Journal of Energy Chemistry ›› 2023, Vol. 79 ›› Issue (4): 201-210.DOI: 10.1016/j.jechem.2022.12.060

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Moderately concentrated electrolyte enabling high-performance lithium metal batteries with a wide working temperature range

Sisi Wang, Zhichen Xue, Fulu Chu, Zengqiang Guan, Jie Lei*, Feixiang Wu*   

  1. School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy, State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan, China
  • Received:2022-11-08 Revised:2022-12-15 Accepted:2022-12-31 Online:2023-04-15 Published:2023-05-30
  • Contact: * E-mail addresses: jielei@xmu.edu.cn (J. Lei), feixiang.wu@csu.edu.cn (F. Wu).

Abstract: The electrolyte integrated with lithium metal anodes is subjected to the issues of interfacial compatibility and stability, which strongly influence the performances of high-energy lithium metal batteries. Here, we report a new electrolyte recipe viz. a moderately concentrated electrolyte comprising of 2.4 M lithium bis (fluorosulfonyl)imide (LiFSI) in a cosolvent mixture of fluorinated ethylene carbonate (FEC) and dimethyl carbonate (DMC) with relatively high ion conductivity. Owing to the preferential decomposition of LiFSI and FEC, an inorganic-rich interphase with abundant Li2O and LiF nanocrystals is formed on lithium metal with improved robustness and ion transfer kinetics, enabling lithium plating/stripping with an extremely low overpotential of ~ 8 mV and the average CE of 97%. When tested in Li||LiFePO4 cell, this electrolyte provides long-term cycling with a capacity retention of 98.3% after 1000 cycles at 1 C and an excellent rate performance of 20 C, as well as an areal capacity of 1.35 mA h cm-2 at the cathode areal loading of 9 mg cm-2. Moreover, the Li||LiFePO4 cell exhibits excellent wide-temperature performances (-40 ~ 60 ℃), including long-term cycling stability over 2600 cycles without visible capacity fading at 0 ℃, as well as extremely high average CEs of 99.6% and 99.8% over 400 cycles under —20 ℃ and 45 ℃.

Key words: Moderately concentrated electrolyte, Wide temperature range, LiFePO4 cathode, Lithium metal battery, Solid electrolyte interphase