Unique double-layer solid electrolyte interphase formed with fluorinated ether-based electrolytes for high-voltage lithium metal batteries

Ruo Wang, Jiawei Li, Bing Han, Qingrong Wang, Ruohong Ke, Tong Zhang, Xiaohu Ao, Guangzhao Zhang*, Zhongbo Liu, Yunxian Qian, Fangfang Pan, Iseult Lynch*, Jun Wang*, Yonghong Deng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Li metal batteries using high-voltage layered oxides cathodes are of particular interest due to their high energy density. However, they suffer from short lifespan and extreme safety concerns, which are attributed to the degradation of layered oxides and the decomposition of electrolyte at high voltage, as well as the high reactivity of metallic Li. The key is the development of stable electrolytes against both high-voltage cathodes and Li with the formation of robust interphase films on the surfaces. Herein, we report a highly fluorinated ether, 1,1,1-trifluoro-2-[(2,2,2-trifluoroethoxy) methoxy] ethane (TTME), as a co-solvent, which not only functions as a diluent forming a localized high concentration electrolyte (LHCE), but also participates in the construction of the inner solvation structure. The TTME-based electrolyte is stable itself at high voltage and induces the formation of a unique double-layer solid electrolyte interphase (SEI) film, which is embodied as one layer rich in crystalline structural components for enhanced mechanical strength and another amorphous layer with a higher concentration of organic components for enhanced flexibility. The Li||Cu cells display a noticeably high Coulombic efficiency of 99.28% after 300 cycles and Li symmetric cells maintain stable cycling more than 3200 h at 0.5 mA/cm2 and 1.0 mAh/cm2. In addition, lithium metal cells using LiNi0.8Co0.1Mn0.1O2 and LiCoO2 cathodes (both loadings ∼3.0 mAh/cm2) realize capacity retentions of >85% over 240 cycles with a charge cut-off voltage of 4.4 V and 90% for 170 cycles with a charge cut-off voltage of 4.5 V, respectively. This study offers a bifunctional ether-based electrolyte solvent beneficial for high-voltage Li metal batteries.

Original languageEnglish
Pages (from-to)532-542
Number of pages11
JournalJournal of Energy Chemistry
Volume88
Early online date13 Oct 2023
DOIs
Publication statusPublished - Jan 2024

Bibliographical note

Funding Information:
The authors are grateful for the financial supports from the Key-Area Research and Development Program of Guangdong Province (2020B090919001), the National Natural Science Foundation of China (22078144) and the Guangdong Natural Science Foundation for Basic and Applied Basic Research (2021A1515010138 and 2023A1515010686).

Publisher Copyright:
© 2023 Science Press

Keywords

  • Cathode electrolyte interphase
  • Fluorinated ether-based electrolytes
  • High-voltage layered oxides
  • Lithium metal batteries
  • Solid electrolyte interphase

ASJC Scopus subject areas

  • Fuel Technology
  • Energy Engineering and Power Technology
  • Energy (miscellaneous)
  • Electrochemistry

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