F5DEE {2-[2-(2, 2-Difluoroethoxy)ethoxy]-1,1,1-Trifluoroethane, >99.0%} as Battery Electrolyte Co-Solvent and Additive, 5-25 g/bottle, CBESAF5DEE

F5DEE (2-[2-(2,2-difluoroethoxy)ethoxy]-1,1,1-trifluoroethane) is an advanced asymmetric fluorinated diether engineered as a high-performance co-solvent, diluent, and interphase-directing additive for next-generation lithium-metal and high-voltage lithium-ion batteries. By integrating a diethylene glycol backbone terminated by two distinct fluorinated alkyl groups (one trifluoroethyl and one difluoroethyl unit), F5DEE achieves a unique blend of solvation capacity, oxidative stability, and interfacial passivation.

Its functional roles in electrolyte engineering are: (1) Solvation Sheath & Anion Coordination: F5DEE modifies the primary lithium-ion coordination shell by discouraging solvent-separated ion pairing and encouraging inner-sphere anion incorporation, which is critical for forming stable, highly conductive interphases. (2) Multifacial Interphase (SEI/CEI) Passivation: Due to its asymmetric fluorination profile, F5DEE undergoes preferential electrochemical reduction during initial formation cycles on the anode—yielding a dense, inorganic-rich Solid Electrolyte Interphase (SEI) heavily enriched with lithium fluoride (LiF)—while also helping passivate high-voltage transition metal oxide cathodes. (3) Localized High-Concentration Electrolyte (LHCE) Integration: When deployed as a structural co-solvent or diluent, F5DEE expands free-solvent volume, lowers bulk liquid viscosity, and enhances separator wettability without disrupting the primary ion-solvent clusters of concentrated salt solutions. (4) Oxidative Stability Enhancement: The terminal fluorinated groups lower the Highest Occupied Molecular Orbital (HOMO) energy level, elevating the anodic stability threshold and suppressing electrolyte degradation during high-voltage operation.

The primary electrochemical domains are: (1) High-Performance Lithium-Metal Batteries (LMBs): Paired with high-capacity lithium anodes and advanced salts (e.g., LiFSI) to achieve high Coulombic efficiencies, suppress dendrite propagation, and extend cycle longevity under lean-electrolyte conditions. (2) High-Voltage Full Cells: Integrated into formulations paired with nickel-rich layered oxide cathodes (such as NMC811) operating above 4.3 V to minimize parasitic side reactions and transition-metal dissolution. (3) Anode-Free and Advanced Systems: Utilized to support uniform plating/stripping behavior on bare current collectors, improving practical energy density.

Part Number	CBESAF5DEE (C-BESA-F5DEE)
CAS	2863676-48-4
Chemical Formula	C6H9F5O2
Appearance	Colorless liquid
Purity	>99.0%
Molecular Weight	208.13 g/mol
Package Size	5 g, 10 g, and 25 g/bottle

Notes: Please store the F5DEE liquid in the dry place (glovebox is the best).

References: 

1. J. Kim, et al. Generative Electrolyte Solvent and Formulation Discovery, JACS Au (2026) 6 (4): 2288–2302.
2. S. T. Oyakhire, et al. Proximity Matters: Interfacial Solvation Dictates Solid Electrolyte Interphase Composition, Nano Lett. (2023) 23 (16): 7524–7531.