Lithium Tetrakis(pentafluorophenyl)borate - Ethyl Ether ComplexCAS #: 155543-02-5

Synonyms 

Lithiotetrakis(pentafluorophenyl) boron(V); Tetrakis(pentafluorophenyl)boron lithium ethyl etherate; Lithium tetrakis(pentafluorophenyl)borate;

Compound Formula: C24BF20Li•C4H10O 

Molecular Weight: 685.98 

Appearance: White to pale yellow crystals 

Melting Point: N/A 

Boiling Point: N/A 

Density: N/A 

Solubility in H2O: N/A 

Exact Mass: 685.993374 g/mol 

Monoisotopic Mass: 685.993374 g/mol 

Charge: 0

Product Introduction: Potassium Bis(fluorosulfonyl)imide (KFSI, CAS #: 155543-02-5)

Potassium bis(fluorosulfonyl)imide, with the chemical formula KN(SO₂F)₂ and CAS number 155543-02-5, is an advanced potassium salt that has emerged as a promising electrolyte material in potassium-ion batteries (PIBs) and other potassium-based electrochemical systems. This white crystalline solid combines high ionic conductivity, excellent thermal stability, and broad compatibility with electrode materials, positioning it as a key enabler for sustainable energy storage solutions that leverage the abundant and low-cost potassium resource.

Chemical & Physical Properties

KFSI exhibits a range of properties that make it a superior choice for potassium-based electrolytes:

Solubility: Highly soluble in various organic solvents, including ethylene carbonate (EC), dimethyl carbonate (DMC), and propylene carbonate (PC), allowing the formulation of high-concentration electrolytes tailored for different battery chemistries.

Ionic Conductivity: Delivers high ionic conductivity (up to 6 mS/cm in optimized solvent mixtures), facilitating efficient potassium-ion transport in battery cells—comparable to leading electrolytes used in potassium-ion systems.

Thermal Stability: Maintains stability at temperatures up to approximately 190°C, significantly higher than conventional potassium salts like potassium hexafluorophosphate (KPF₆), reducing the risk of thermal runaway in batteries.

Electrochemical Window: Boasts a wide electrochemical stability window (up to 4.8 V vs. K⁺/K), compatible with high-voltage cathodes (e.g., potassium manganese oxide, K₂Mn₄O₉) used in high-energy-density PIBs.

Hydrolytic Stability: More resistant to hydrolysis than KPF₆, generating fewer corrosive byproducts (e.g., HF) when exposed to moisture, which enhances the long-term durability of battery systems.

Key Applications in Energy Storage

Potassium bis(fluorosulfonyl)imide (CAS 155543-02-5) plays a pivotal role in advancing potassium-based energy storage technologies:

Potassium-Ion Batteries (PIBs): Serves as a primary electrolyte salt in PIBs, which are gaining attention as a low-cost alternative to lithium-ion batteries for stationary energy storage, grid applications, and low-power devices. Its high conductivity and stability improve PIB cycle life and rate performance.

Potassium-Metal Batteries: Enables the development of potassium-metal batteries by forming a stable solid electrolyte interphase (SEI) on potassium metal anodes, suppressing dendrite growth and enhancing battery safety.

Potassium-Based Supercapacitors: Utilized in electrolytes for potassium-ion supercapacitors, where its high conductivity and stability contribute to improved power density and cycle life, making it suitable for short-duration energy storage and power delivery.

Hybrid Energy Storage Systems: Explored in hybrid systems combining batteries and supercapacitors, where its versatility supports seamless integration and optimized performance across different energy and power requirements.

Advantages Over Conventional Potassium Salts

KFSI offers significant benefits compared to traditional potassium electrolyte salts like KPF₆ and potassium perchlorate (KClO₄):

Cost-Effectiveness: Leverages the abundance of potassium, reducing reliance on scarce lithium resources and lowering overall battery production costs, making it ideal for large-scale energy storage.

Stability: Superior thermal and chemical stability minimizes electrolyte decomposition, reducing gas generation and improving battery safety—a critical factor for stationary storage applications.

Compatibility: Works with a broad range of PIB electrode materials, including hard carbon anodes and Prussian blue analog cathodes, supporting the development of high-performance potassium-ion systems.

Performance: Enhances cycle life (by 25–40% in many formulations) and high-rate capability, making PIBs more competitive with other battery technologies in specific use cases.

Synthesis & Quality Control

KFSI is synthesized through precise processes to ensure high purity and consistency:

Precursor Formation: Fluorosulfonyl isocyanate (FSO₂NCO) reacts with hydrogen fluoride (HF) to form bis(fluorosulfonyl)amine (HFSI), a key intermediate.

Potassiation: HFSI is neutralized with potassium hydroxide (KOH) or potassium carbonate (K₂CO₃) in an organic solvent, followed by crystallization to produce KFSI.

Purification: Recrystallization from anhydrous solvents and drying under vacuum remove residual moisture and impurities, ensuring purity levels of 99.9% or higher.

Quality control involves ion chromatography (IC) for anion analysis, inductively coupled plasma mass spectrometry (ICP-MS) for trace metal detection, and Karl Fischer titration to verify moisture content (typically below 10 ppm).

Safety & Handling

Proper handling of KFSI is essential due to its properties:

Hygroscopicity: Absorbs moisture readily from the air, which can affect performance; store in sealed containers under an inert atmosphere (e.g., nitrogen or argon).

Toxicity: May cause skin and eye irritation; use chemical-resistant gloves, goggles, and a lab coat when handling. In case of contact, rinse thoroughly with water.

Reactivity: Avoid contact with strong reducing agents and combustible materials, as it may act as an oxidizer under extreme conditions.

Storage: Keep in a cool, dry, well-ventilated area, away from heat sources and direct sunlight.

Refer to the product’s Safety Data Sheet (SDS) for detailed safety guidelines.

Packaging & Availability

We offer KFSI in various forms to suit different applications:

Anhydrous Powder: Packaged in moisture-proof aluminum bags (100g–10kg) with inert gas purging to prevent hydration.

Solutions: Available as pre-dissolved solutions (5–20% w/w) in organic solvents (e.g., EC/DMC mixtures) for easy integration into electrolyte formulations, packaged in 1L–50L containers.

Bulk quantities (50kg+ drums) are available for industrial-scale production. Custom purities and particle sizes can be provided to meet specific customer requirements.

For technical specifications, pricing, or sample requests, contact our sales team, which specializes in advanced electrolyte materials for potassium-based energy storage.

Health & Safety Information 

Signal Word: Danger 

Hazard Statements: N/A 

Hazard Codes: F 

Risk Codes: N/A 

Safety Statements: N/A 

Transport Information: N/A

Chemical Identifiers

 Linear Formula: C24BF20Li•C4H10O 

Pubchem CID: 23701484 

MDL Number: MFCD01861289 

IUPAC Name: lithium; tetrakis(2,3,4,5,6-pentafluorophenyl)boranuide 

SMILES: [Li+].[B-](C1=C(C(=C(C(=C1F)F)F)F)F)(C2=C(C(=C(C(=C2F)F)F)F)F)(C3=C(C(=C(C(=C3F)F)F)F)F)C4=C(C(=C(C(=C4F)F)F)F)F 

InchI Identifier: InChI=1S/C24BF20.Li/c26-5-1(6(27)14(35)21(42)13(5)34)25(2-7(28)15(36)22(43)16(37)8(2)29,3-9(30)17(38)23(44)18(39)10(3)31)4-11(32)19(40)24(45)20(41)12(4)33;/q-1;+1 

InchI Key: WTTFKRRTEAPVBI-UHFFFAOYSA-N

Packing of Standard Packing: 

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 735 gallon liquid totes Special package is available on request.