Publication Date

1-22-2026

Document Type

Article

Publication Title

Frontiers in Chemistry

Volume

14

DOI

10.3389/fchem.2026.1744630

Abstract

For aqueous lithium-ion batteries (A-LIBs), the hydrogen evolution reaction (HER) poses a significant challenge, as it competes with the primary electrochemical processes of the anode, resulting in capacity loss and reduced cycling stability. In this study, we investigate the use of fluorine-based additives in anodes to mitigate HER in LIBs with aqueous electrolytes including low or high amounts of salt (water-in-salt electrolytes (WiSE)). We synthesized and incorporated three distinct materials into TiO2(B) anodes: aluminum fluoride (AlF3), lithium fluoride (LiF), and 1H,1H,2H, 2H-perfluorooctyltriethoxysilane (FAS) using a solution-based method. Among these fluorides containing composite anodes, FAS containing anodes delayed HER onset potentials of WiSE by 45–160 mV (1.2 m (molality) or 21 m (Lithium bis (trifluoromethanesulfonyl) imide in H2O)) compared to the bare TiO2 (B) anodes. Among these fluorides, FAS demonstrated the highest HER delay with the smallest amount of additives due to its hydrophobic nature. These findings underscore the effect of fluorine-based passivation layers in mitigating the HER, potentially expanding the energy density, and improving the operational stability of anodes in A-LIBs, thereby paving the way for their broader application in sustainable energy storage.

Funding Number

DE-AC02-05CH11231

Funding Sponsor

Basic Energy Sciences

Keywords

aqueous lithium-ion batteries, fluorides, hydrogen evolution reaction, silanization, TiO2 nanorods, water-in-salt electrolytes

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Chemical and Materials Engineering

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