Lithium Salicylate MonohydrateCAS #: 75575-50-7

Synonyms

 Salicylic Acid Lithium Salt Monohydrate

Compound Formula: C7H7LiO4

 Molecular Weight: 162.07 

Appearance: White powder or crystals 

Melting Point: N/A 

Boiling Point: N/A 

Density: N/A 

Solubility in H2O: N/A 

Exact Mass: 162.050438 g/mol 

Monoisotopic Mass: 162.050438 g/mol 

Charge: 0

Product Introduction: Potassium Bis(fluorosulfonyl)imide (KFSI, CAS #: 75575-50-7)

Potassium bis(fluorosulfonyl)imide, with the chemical formula K[N(SO₂F)₂] and CAS number 75575-50-7, is an advanced fluorinated salt gaining prominence in next-generation energy storage and specialty chemical applications. Composed of potassium cations (K⁺) and bis(fluorosulfonyl)imide anions ([N(SO₂F)₂]⁻), this white crystalline compound combines exceptional thermal stability, high ionic conductivity, and low hygroscopicity—properties that address key limitations of traditional electrolytes like potassium hexafluorophosphate (KPF₆). As demand grows for high-performance potassium-ion batteries (PIBs) and safer energy storage systems, KFSI has emerged as a critical material, offering a balance of performance, safety, and compatibility with emerging electrode chemistries.

Chemical & Physical Properties

KFSI’s unique molecular structure endows it with properties that set it apart from conventional potassium salts:

Solubility: Highly soluble in polar organic solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC), forming electrolytes with concentrations up to 1.2 M. This solubility enables ionic conductivities of 10–14 mS/cm in optimized blends—surpassing KPF₆ in high-power applications.

Thermal Stability: Exhibits exceptional thermal stability, decomposing above 300°C—far higher than KPF₆ (decomposes >200°C) and many other fluorinated salts. This stability reduces the risk of thermal runaway in batteries, a critical safety advantage.

Hygroscopicity: Low hygroscopicity compared to KPF₆, with minimal reaction with moisture even at 50% relative humidity. This simplifies manufacturing and storage, reducing the need for strict moisture control (moisture tolerance up to 100 ppm in electrolytes).

Density & Structure: Has a density of 2.3 g/cm³ and a molar mass of 244.27 g/mol, with a layered crystal structure that facilitates efficient ion dissociation in solution.

Electrochemical Window: Boasts a wide electrochemical stability window up to 5.2 V vs. K⁺/K, compatible with high-voltage PIB cathodes such as Prussian blue analogs and Na₂Mn[Fe(CN)₆]—enabling higher energy densities than KPF₆-based systems.

Key Applications

Potassium bis(fluorosulfonyl)imide (CAS 75575-50-7) is revolutionizing energy storage and specialty chemistry:

Potassium-Ion Batteries (PIBs): Serves as a premium electrolyte salt in PIBs, where its high conductivity and stability enhance cycle life and rate performance. In laboratory tests, KFSI-based electrolytes enable PIBs with hard carbon anodes to achieve 3,000+ cycles with 80% capacity retention—double the lifespan of KPF₆-based systems. Its ability to form a robust solid electrolyte interphase (SEI) layer, rich in KF and organic fluorides, minimizes electrolyte decomposition and dendrite growth.

Hybrid Ion Batteries: Used in Li-K and Na-K hybrid batteries to stabilize ion transport across mixed cation systems. KFSI’s compatibility with both lithium and sodium ions allows these hybrids to achieve energy densities exceeding 350 Wh/kg while reducing reliance on lithium.

Ionic Liquid Synthesis: Acts as a precursor in the preparation of potassium-based ionic liquids, which are used as non-flammable electrolytes in high-temperature batteries and as solvents in green chemical synthesis. These ionic liquids exhibit low volatility and high thermal stability, making them suitable for industrial processes.

Electrochemical Devices: Employed in supercapacitors and fuel cells to improve ion mobility and reduce internal resistance. In supercapacitors, KFSI electrolytes enhance power density by 20% compared to traditional aqueous electrolytes.

Catalysis: Functions as a Lewis acid catalyst in fluorination reactions, facilitating the synthesis of pharmaceutical intermediates and agrochemicals with high selectivity (up to 95% yield in certain fluorination steps).

Advantages & Limitations

KFSI offers significant benefits over traditional potassium salts, with a few considerations:

Safety Profile: Superior thermal stability and low toxicity reduce fire and explosion risks in batteries, making it ideal for consumer electronics and electric vehicles. Its low HF generation upon hydrolysis (compared to KPF₆) minimizes corrosion of battery components.

Performance Metrics: Higher ionic conductivity and wider electrochemical window enable higher energy and power densities, addressing key bottlenecks in PIB commercialization.

Compatibility: Works with a broader range of electrode materials, including high-voltage cathodes and alloy-based anodes, expanding the design space for advanced batteries.

Limitations: Higher production costs than KPF₆ (approximately 2–3x) due to complex synthesis, limiting large-scale adoption in cost-sensitive applications. While less hygroscopic than KPF₆, it still requires dry handling to maintain purity.

Synthesis & Quality Control

KFSI is produced via multi-step processes to ensure high purity:

Sulfonylation: Fluorosulfonic acid (HSO₃F) reacts with ammonia (NH₃) to form bis(fluorosulfonyl)amine (H[N(SO₂F)₂]).

Neutralization: The amine is neutralized with potassium hydroxide (KOH) or potassium carbonate (K₂CO₃) in anhydrous solvent: H[N(SO₂F)₂] + KOH → K[N(SO₂F)₂] + H₂O.

Purification: Recrystallization from anhydrous acetonitrile or dimethylformamide (DMF) removes impurities, achieving purity levels of 99.9% for battery-grade material.

Quality control includes:

Ion chromatography to verify anion purity and detect residual sulfates or fluorides.

Inductively coupled plasma mass spectrometry (ICP-MS) to measure trace metals (Fe, Na, Ca <5 ppm).

Thermogravimetric analysis (TGA) to confirm thermal stability (>300°C decomposition onset).

Safety & Handling

Proper handling of KFSI is guided by its chemical properties:

Toxicity: Low acute toxicity, but inhalation of dust or contact with moisture can release trace amounts of HF, causing mild irritation. Chronic exposure to fluoride ions may affect bone health.

Handling: Use in well-ventilated fume hoods with moisture levels <10% RH. Wear PTFE gloves, splash goggles, and a dust respirator to prevent contact.

Storage: Keep in airtight, moisture-proof containers (e.g., stainless steel or HDPE) in a cool, dry area, separated from strong acids and reducing agents.

Disposal: Classified as a hazardous waste due to fluoride content; dispose of in accordance with local regulations (e.g., EPA RCRA in the U.S.). Neutralize spills with calcium carbonate to form insoluble CaF₂.

Refer to the product’s Safety Data Sheet (SDS) for detailed emergency protocols.

Packaging & Availability

KFSI is available in forms tailored to research and industrial needs:

Battery Grade: 1kg–25kg sealed aluminum drums with argon purging, suitable for electrolyte production.

Research Grade: 100g–5kg bottles in moisture-barrier packaging for laboratory use, with ultra-low metal impurities.

Solution Form: Pre-dissolved in organic solvent blends (e.g., 1.0 M in EC/DMC) in 1L–20L containers for immediate use in battery assembly.

Global production is led by manufacturers in China, Japan, and Europe, with annual capacity exceeding 500 tons and growing to meet PIB demand. High-purity grades (99.99%) are available for advanced electronics and catalysis applications.

For technical specifications, custom formulations, or supply chain insights, contact our team specializing in advanced electrolytes and fluorinated materials.

Health & Safety Information

 Signal Word: Warning 

Hazard Statements: H315-H319 

Hazard Codes: N/A 

Risk Codes: N/A 

Safety Statements: N/A 

Transport Information: N/A

Chemical Identifiers

 Linear Formula: C7H5LiO3• xH2O 

Pubchem CID: 91886581 

IUPAC Name: lithium; 2-hydroxybenzoate; hydrate 

SMILES: [Li+].C1=CC=C(C(=C1)C(=O)[O-])O.O 

InchI Identifier: InChI=1S/C7H6O3.Li.H2O/c8-6-4-2-1-3-5(6)7(9)10;;/h1-4,8H,(H,9,10);;1H2/q;+1;/p-1 

InchI Key: SKQWWJVTSPXPSF-UHFFFAOYSA-M

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.