TFTFE (1,1,2,2-Tetrafluoroethyl 2,2,2-trifluoroethyl ether, >99.95%) as Battery Electrolyte Solvent, 50-200 g/bottle, CBESTFTFE

TFTFE (1,1,2,2-Tetrafluoroethyl 2,2,2-trifluoroethyl ether, or HFE-347), is an asymmetric fluorinated ether used primarily as a non-solvating diluent / co-solvent in localized high-concentration electrolytes (LHCEs) and high-voltage lithium-metal battery systems. It combines a tetrafluoroethyl tail (-CF2CHF2) on one side of the ether oxygen and a trifluoroethyl tail (-CH2CF3) on the other, creating an asymmetric fluorination pattern that balances low viscosity, low volatility, and high anodic oxidation stability.

Weak Solvation / Non-Solvating Diluent in LHCEs: Like its symmetric counterparts (BTFE and TTE), TFTFE serves as a key diluent for Localized High-Concentration Electrolytes (LHCE): (1) Low Donor Power: The presence of seven fluorine atoms strongly withdraws electron density from the central ether oxygen. Consequently, TFTFE has an extremely low Gutmann Donor Number (DN) and cannot dissolve lithium salts directly. (2) Preservation of CIP/AGG Solvation Clusters: When added to a concentrated salt-in-solvent mixture (e.g., LiFSI in DME or trimethyl phosphate), TFTFE dilutes the bulk liquid to lower macroscopic viscosity without disrupting the beneficial Contact Ion Pair (CIP) and Aggregate (AGG) networks surrounding Li+ ions.

Sacrificial Anode Passivation (LiF-Rich SEI): Under the strongly reductive potentials of metallic lithium or graphite anodes (<0.5 V vs. Li/Li+), TFTFE undergoes sacrificial chemical/electrochemical decomposition: It releases fluorinated species that convert the surface interphase into a dense, mechanically robust, lithium fluoride (LiF)-rich Solid Electrolyte Interphase (SEI). This high-LiF interphase suppresses continuous parasitic solvent consumption and prevents non-uniform lithium electrodeposition and dendrite growth.

Wide Oxidation Window & Reduced Flammability: (1) High Oxidation Threshold: The strongly electron-withdrawing fluorinated groups lower the Highest Occupied Molecular Orbital (HOMO) energy level of TFTFE, pushing its anodic oxidation stability window beyond 4.8-5.0 V vs. Li/Li+. This allows ether-based electrolyte formulations to operate safely with high-voltage nickel-rich cathodes (such as NMC811 or NMC955). (2) Thermal Safety: TFTFE features a high fluorine-to-carbon ratio, which elevates its flash point, suppresses vapor flammability, and reduces overall heat generation during extreme thermal abuse scenarios.

Part Number	CBESTFTFE (C-BES-TFTFE)
CAS	406-78-0
Chemical Formula	C4H3F7O
Appearance	Colorless Liquid
Purity	>99.5%
Molecular Weight	200.05 g/mol
Density	1.49 g/mL
Boling Point	56 °C
Package Size	50 g, 100 g, and 200 g/bottle

Notes: Please store the TFTFE solution in the glovebox due to its sensitivity to humidity and oxygen 

References: 

1. H. Lu, et al. Application of Partially Fluorinated Ether for Improving Performance of Lithium/Sulfur Batteries, J. Electrochem. Soc., 2015, 162, A1460.
2. W. Yao, et al. Inner–Outer Sheath Synergistic Shielding of Polysulfides in Asymmetric Solvent-Based Electrolytes for Stable Sodium–Sulfur Batteries, J. Am. Chem. Soc.,  2025, 147, 14, 12061–12074.