Page 188 - Read Online

Wang et al. Energy Mater 2023;3:300040 https://dx.doi.org/10.20517/energymater.2023.28 Page 13 of 14

films on the surfaces of the cycled LCO and NCM811 cathodes with the carbonate electrolyte system have
an average thickness of 11.5 nm on the surface of the cycled LCO and reaches 18.2 nm at the thickest part
on the surface of the cycled NCM811. Besides, the overall distribution of the CEI films formed with the
carbonate electrolyte system is not uniform, and there are thick areas and bare areas observed on the
surface. What is worse, the irregular zigzag areas are observed on the surface of the cycled cathodes,
indicating the structural deterioration of the cathode materials at high voltage.

CONCLUSION
In this work, a highly fluorinated ether, namely TTME, was added to the DME/LiFSI electrolyte system to
obtain a fluorinated ether electrolyte. This electrolyte avoided the problem of co-intercalation of DME with
graphite and stabilized the performance of the Li||graphite cells (91.7% capacity retention for 300 cycles).
Additionally, the electrolyte also overcame the challenge of high-voltage cathodes by providing a stable CEI.
Both the NCM811||graphite cells and the LCO||graphite cells delivered excellent cycling performance at
high charge cut-off voltages. Through multiple characterizations, it could be concluded that the dense and
strong SEI and CEI formed by the fluorinated ether electrolyte on the anode and cathode sides, respectively,
are the essential guarantee for stable cycling. These results have provided design principles for the
application of ether electrolytes in high-voltage LIBs.

DECLARATIONS
Authors’ contributions
Made substantial contributions to the conception and design of the study and performed data analysis and
interpretation: Wang R, Zhang G, Wang J, Lynch I, Deng Y
Performed data acquisition and provided administrative, technical, and material support: Wang H, Zhao H,
Yuan M, Liu Z, Zhang T, Qian Y

Availability of data and materials
All data are available in the manuscript and the Supplementary Material.

Financial support and sponsorship
This work was supported by 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).

Conflicts of interest
All authors declared that there are no conflicts of interest.

Ethical approval and consent to participate
Not applicable.

Consent for publication
Not applicable.

Copyright
© The Author(s) 2023.