[BMIM][TFSI] (1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, >99.0%) Ionic Liquid as Electrolyte Solvent and Additive, CESAILBMIMTFSI

[BMIM][TFSI] (1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) is one of the most versatile and commercially popular hydrophobic ionic liquids in modern electrochemistry. It is prized for its combination of a wide electrochemical stability window, high thermal stability, and significantly lower viscosity compared to other [BMIM]-based salts like [BMIM][PF6].

Lithium-Ion and Lithium-Metal Batteries: [BMIM][TFSI] is used both as a co-solvent and a safety additive. (1) Flame Retardancy: Even at 10–20% concentration in carbonate electrolytes, it drastically reduces flammability and vapor pressure, preventing "thermal runaway." (2) Interfacial Stability: It helps in the formation of a robust Solid Electrolyte Interphase (SEI). Unlike [EMIM]+ (which can exfoliate graphite), the bulkier [BMIM]+ cation is generally more compatible with carbon-based anodes when paired with appropriate film-forming additives like Vinylene Carbonate (VC). (3) Lithium-Sulfur (Li-S) Batteries: It is a preferred solvent for Li-S systems because it has low polysulfide solubility, which helps suppress the "shuttle effect" that usually kills the cycle life of these batteries.

CO2 Electroreduction (CO2RR): In CO2 reduction, [BMIM][TFSI] is often used in gas-diffusion electrode (GDE) setups. (1) Water Management: Its hydrophobic nature creates a "water-lean" interface. This is crucial for suppressing the competing Hydrogen Evolution Reaction (HER), allowing for much higher Faradaic Efficiencies toward Carbon Monoxide (CO) or Ethylene. (2) CO2 Solubility: CO2 is significantly more soluble in [BMIM][TFSI] than in water, which helps overcome the mass-transport limitations that often restrict current density in aqueous cells.

Supercapacitors (EDLCs): It is a leading electrolyte for high-voltage supercapacitors. By moving from aqueous electrolytes to [BMIM][TFSI], the cell voltage can be increased from 1.2 V to 3.2 V. Because it doesn't freeze or boil easily, [BMIM][TFSI] allows supercapacitors to operate in extreme environments (e.g., -20°C to 100°C) where water-based systems would fail.

Part Number	CESAILBMIMTFSI (C-ESA-ILBMIMTFSI) Also named as [BMIM][Tf2N]
CAS	174899-83-3
Chemical Formula	C10H15F6N3O4S2
Appearance	Colorless liquid
Purity	>99.0% (Battery Grade) Water level: <500 ppm
Molecular Weight	419.36 g/mol
Density	1.45 g/cm3
Package Size	25 or 100 g/bottle

Notes: Please try to store the [BMIM][TFSI] ionic liquid in the dry place. 

References: 

1. H. Tu, et al. Solvation and interfacial chemistry in ionic liquid based electrolytes toward rechargeable lithium-metal batteries, J. Mater. Chem. A, 2024, 12, 33362-33391.
2. B. Ratschmeier, et al. Cations of Ionic Liquid Electrolytes Can Act as a Promoter for CO2 Electrocatalysis through Reactive Intermediates and Electrostatic Stabilization, J. Phys. Chem. C 2021, 125, 30, 16498–16507. 
3. B. J. McNicholas, et al., Electrocatalysis of CO2 Reduction in Brush Polymer Ion Gels, J. Am. Chem. Soc. 2016, 138, 35, 11160–11163.
4. L. Sun, et al., Ionic Liquid-Based Redox Active Electrolytes for Supercapacitors, Adv. Funct. Mater., 2022, 32, 2203611.