BFE {Bis(2-fluoroethyl) Ether, >99.0%} as Battery Electrolyte Co-Solvent and Additive, 5-25 g/bottle, CBESABFE

Bis(2-fluoroethyl) ether (commonly designated as BFE) is a symmetrically fluorinated linear ether engineered as an advanced co-solvent, solvation-sheath modifier, and interphase-directing additive for next-generation lithium-metal and lithium-sulfur batteries. By introducing a single fluorine atom onto each terminal ethyl group of a traditional diethyl ether backbone, BFE strikes a balanced compromise between the high solvation strength of unfluorinated glymes and the exceptional electrochemical stability of heavily perfluorinated ethers.

Its functional roles in electrolyte engineering are: (1) Balanced Solvation Sheath Modification: BFE coordinates effectively with lithium ions (Li+) while promoting dynamic exchange within the primary solvation shell. This prevents excessive solvent-separated ion pairing and facilitates beneficial counter-anion incorporation into the inner coordination sphere. (2) Anion-Derived Solid Electrolyte Interphase (SEI) Formation: Due to its tailored reduction potential, BFE participates in early-stage electrochemical reduction on reactive lithium or sodium metal anodes. This reductive breakdown assists in constructing a robust, inorganic-rich SEI layer heavily enriched with metal fluorides (LiF), mitigating dendrite propagation and dead lithium formation. (3) Oxidative Stability Enhancement: The presence of the terminal fluorine atoms lowers the Highest Occupied Molecular Orbital (HOMO) energy level compared to standard diethyl ether, elevating the anodic stability threshold and suppressing premature oxidation during high-voltage operation. (4) Polysulfide Solvation Control (Li-S Systems): BFE exhibits moderate dissolving power toward lithium polysulfide intermediates, helping restrain the destructive polysulfide shuttle effect while maintaining active charge-transfer kinetics in sulfur cathodes.

The primary electrochemical domains are: (1) High-Performance Lithium-Metal Batteries (LMBs): Paired with high-capacity lithium anodes and advanced fluorosulfonylimide salts to achieve high Coulombic efficiencies and extended cycle life under lean-electrolyte configurations. (2) Lithium-Sulfur (Li-S) Chemistries: Integrated as a functional co-solvent to suppress self-discharge, improve calendar life, and balance mass transport parameters in low- and high-sulfur-loading electrodes.

Part Number	CBESABFE (C-BESA-BFE)
CAS	373-21-7
Chemical Formula	C4H8F2O
Appearance	Colorless liquid
Purity	>99.0%
Molecular Weight	110.10 g/mol
Package Size	5 g, 10 g, and 25 g/bottle

Notes: Please store the BFE liquid in the dry place (glovebox is the best).

References: 

1. G. Zhang, et al. A monofluoride ether-based electrolyte solution for fast-charging and low-temperature non-aqueous lithium metal batteries, Nature Communications, 2023, 14, 1081
2. Y. Lin, et al. Impact of the fluorination degree of ether-based electrolyte solvents on Li-metal battery performance, J. Mater. Chem. A (2024) 12 (5): 2986–2993.