F6DEE {1,2-Bis(2,2,2-trifluoroethoxy)ethane, >99.0%} as Battery Electrolyte Co-Solvent and Additive, 5-25 g/bottle, CBESAF6DEE

F6DEE (1,2-bis(2,2,2-trifluoroethoxy)ethane, widely known in literature as BTFE) is a symmetric, heavily fluorinated diether engineered as a high-performance co-solvent, structural diluent, and interphase-directing additive for next-generation lithium-metal and high-voltage lithium-ion batteries. By flanking a central ethylene glycol backbone with two fully fluorinated 2,2,2-trifluoroethyl groups (totaling six fluorine atoms), F6DEE achieves exceptional resistance to oxidation at the expense of moderated solvation strength compared to lower-fluorinated homologues.

Its functional roles in electrolyte engineering are: (1) Localized High-Concentration Electrolyte (LHCE) Diluent: F6DEE is predominantly deployed as an inert or weakly interacting diluent. It expands the free-solvent volume and lowers bulk liquid viscosity, enabling rapid separator wetting and facile ionic transport while keeping concentrated salt clusters intact. (2) Oxidative Stability Enhancement: Because of its heavy fluorination, F6DEE exhibits superior anodic stability, effectively suppressing oxidative decomposition and electrolyte breakdown when operating high-voltage transition metal oxide cathodes.  (3) Anion-Derived Solid Electrolyte Interphase (SEI) Passivation: F6DEE actively promotes the reductive decomposition of counter-anions (such as FSI- from LiFSI) alongside its own breakdown during early-stage cycling. This yields a dense, inorganic-rich Solid Electrolyte Interphase (SEI) heavily enriched with lithium fluoride (LiF) on reactive lithium metal anodes. (4) Mitigation of Conduction Penalties via Balancing: While high fluorination degrees maximize oxidative stability, they can restrict bulk ionic conductivity if over-utilized. Consequently, F6DEE is structurally benchmarked against lower-fluorinated ethers (like F4DEE and F5DEE) to balance interfacial protection with rapid charge-transfer kinetics.

The primary electrochemical domains are: (1) High-Performance Lithium-Metal Batteries (LMBs): Paired with high-capacity lithium anodes and concentrated salt solutions to achieve high Coulombic efficiencies, suppress dendrite propagation, and prevent dead lithium accumulation under lean-electrolyte conditions. (2) High-Voltage Full Cells: Integrated into formulations coupled with nickel-rich layered oxide cathodes (such as NMC811) operating above 4.3 V to prevent transition-metal dissolution and parasitic oxidative side reactions.

Part Number	CBESAF6DEE (C-BESA-F6DEE)
CAS	80054-75-7
Chemical Formula	C6H8F6O2
Appearance	Colorless liquid
Purity	>99.0%
Molecular Weight	226.12 g/mol
Package Size	5 g, 10 g, and 25 g/bottle

Notes: Please store the F6DEE liquid in the dry place (glovebox is the best).

References: 

1. Z. Yu, et al. Rational solvent molecule tuning for high-performance lithium metal battery electrolytes, Nature Energy, 2022, 7, 94–106.
2. X. Gao, et al. Electrolytes with moderate lithium polysulfide solubility for high-performance long-calendar-life lithium–sulfur batteries, 2023, DOI: 10.1073/pnas.2301260120