BTFE {Bis(2,2,2-trifluoroethyl) ether, >99.5%} as Battery Electrolyte Co-Solvent, 10-50 g/bottle, CBESBTFE

Bis(2,2,2-trifluoroethyl) ether (BTFE, formula CF3CH2-O-CH2CF3) is a symmetrical fluorinated ether co-solvent / diluent widely utilized in non-aqueous electrolytes for lithium-metal, high-voltage lithium-ion, and localized high-concentration electrolytes (LHCEs). It combines two strongly electron-withdrawing trifluoromethyl (-CF3) groups attached to an ether backbone, fundamentally altering its solvation capability, flammability, and electrochemical window compared to standard unfluorinated ethers like DME or DEE.

Non-Solvating Diluent in LHCEs: BTFE is a classic "diluent" solvent used to formulate Localized High-Concentration Electrolyte (LHCE) systems: (1) Solvation Behavior: Because of the strong electron-withdrawing effect of the six fluorine atoms, the oxygen atom in BTFE has extremely low donor power (low Gutmann Donor Number). As a result, BTFE does not dissolve lithium salts directly and does not participate in the primary Li+ solvation sheath. (2) Microstructure Preservation: When added to a high-concentration salt/solvent mixture (e.g., 4M LiFSI in DME), BTFE dilutes the bulk viscosity and enhances ionic transport without breaking up the localized salt-solvent contact ion pair (CIP) and aggregate (AGG) clusters.

High Oxidation Stability for High-Voltage Cathodes: Unfluorinated ethers typically decompose at potentials above 4.0 V vs. Li/Li+. The high fluorine content significantly lowers the Highest Occupied Molecular Orbital (HOMO) energy level of BTFE. This expands the anodic oxidation stability window beyond 4.5-5.0 V, making ether-based electrolytes compatible with nickel-rich cathodes (NMC811, NMC955) and high-voltage cobalt systems.

Inorganic-Rich Interphase Formation & Flammability Reduction: Anode Stability: Under reductive potentials at the Li metal anode, BTFE undergoes sacrificial decomposition to yield a dense, mechanically robust, lithium fluoride (LiF)-rich Solid Electrolyte Interphase (SEI). Safety: The high fluorine-to-carbon ratio drastically elevates the flash point and suppresses flame propagation, imparting non-flammable or self-extinguishing properties to carbonate and ether electrolyte formulations.

Part Number	CBESBTFE (C-BES-BTFE)
CAS	333-36-8
Chemical Formula	(CF3CH2)2O
Appearance	Colorless Liquid
Purity	>99.5% (Battery Grade)
Molecular Weight	182.06 g/mol
Boiling Point	~62-63 °C (lit.)
Density	1.404 g/mL at 25 °C (lit.)
Package Size	10 g, 25 g, and 50 g/bottle

Notes: Please try to store the BTFE liquid in a dry place (glovebox is the best)

References: 

1. R. May, et al. Fluorinated ether decomposition in localized high concentration electrolytes, Journal of Power Sources, 2023, 553, 232299.
2. M. L. Gordin, et al. Bis(2,2,2-trifluoroethyl) Ether As an Electrolyte Co-solvent for Mitigating Self-Discharge in Lithium–Sulfur Batteries, ACS Appl. Mater. Interfaces (2014) 6 (11): 8006–8010.