Lithium Silicon AlloyCAS #: 68848-64-6

Synonyms

 Li-Si, Lithium Silicide, Lihtium-Silicon, LixSi, Li15Si4, Li13Si4, Li7Si, Li6-7Si2 ,Lithiated Silicon

Compound Formula: LiSi 

Molecular Weight: 35.03 

Appearance: Gray to black powder or lump 

Melting Point: 700 °C 

Boiling Point: N/A 

Density: N/A 

Solubility in H2O: Reacts violently 

Exact Mass: 34.992931 g/mol 

Monoisotopic Mass: 34.992931 g/mol

Product Introduction: Potassium Hexafluorophosphate (KPF₆, CAS #: 68848-64-6)

Potassium hexafluorophosphate, with the chemical formula KPF₆ and CAS number 68848-64-6, is a versatile inorganic salt composed of potassium cations (K⁺) and hexafluorophosphate anions (PF₆⁻). This white, crystalline solid is prized for its high solubility in polar organic solvents, excellent thermal stability, and electrochemical inertness, making it a critical material in energy storage, chemical synthesis, and industrial processes. Its unique combination of fluoride and phosphorus components enables specialized applications in batteries, catalysis, and analytical chemistry.

Chemical & Physical Properties

KPF₆ exhibits a set of properties that underpin its industrial utility:

Solubility: Highly soluble in polar organic solvents such as acetonitrile, propylene carbonate (PC), and dimethyl carbonate (DMC), with solubility exceeding 1 M in many cases. It is moderately soluble in water (approximately 8.3 g/100 mL at 20°C) and insoluble in non-polar solvents like hexane, making it ideal for electrolyte formulations.

Thermal Stability: Decomposes at temperatures above 500°C, releasing toxic phosphorus pentafluoride (PF₅) and potassium fluoride (KF). This high thermal resilience allows use in high-temperature applications such as battery testing and industrial catalysis.

Hygroscopicity: Moderately hygroscopic, absorbing moisture from the air to form hydrated crystals. This necessitates storage in dry environments to prevent caking and degradation.

Density & Structure: Has a density of 2.554 g/cm³ and a molar mass of 184.07 g/mol, with a cubic crystal structure that contributes to its stability and low reactivity with most organic compounds.

Electrochemical Inertness: Exhibits a wide electrochemical stability window (up to 5.0 V vs. Li⁺/Li), making it compatible with high-voltage electrode materials in batteries.

Key Applications

Potassium hexafluorophosphate (CAS 68848-64-6) is employed across diverse industries, leveraging its solubility and stability:

Energy Storage: Battery Electrolytes

Serves as a key electrolyte salt in potassium-ion batteries (PIBs) and hybrid lithium-potassium batteries. Its high solubility in organic solvents enables the formation of conductive electrolytes that support efficient ion transport, while its electrochemical stability prevents decomposition at high voltages. In PIBs, KPF₆-based electrolytes enhance cycle life and reduce capacity fade, making them suitable for grid storage and portable electronics.

Chemical Synthesis: Catalyst and Fluorinating Agent

Acts as a source of PF₆⁻ ions in organometallic chemistry, stabilizing cationic catalysts in reactions such as olefin polymerization and hydrogenation. It also functions as a mild fluorinating agent in organic synthesis, facilitating the introduction of fluoride ions into pharmaceutical intermediates and agrochemicals.

Ion Exchange and Separation

Used in ion chromatography as an eluent additive to separate and detect anions in environmental and biological samples. Its ability to form stable complexes with certain metal ions makes it useful in solvent extraction processes for recovering precious metals like gold and platinum.

Electroplating and Surface Treatment

Added to electroplating baths for noble metals (e.g., gold, silver) to improve coating uniformity and adhesion. The PF₆⁻ anion helps regulate metal ion concentration in the bath, preventing the formation of undesirable deposits.

Laboratory Research

A common reagent for preparing ionic liquids, which are used as green solvents in chemical reactions and as electrolytes in advanced batteries. It is also used to study ion solvation and transport in electrochemical systems.

Advantages & Limitations

KPF₆ offers distinct benefits alongside specific considerations:

Solvent Compatibility: Its solubility in a wide range of organic solvents provides flexibility in formulating electrolytes and reaction media, outperforming less soluble fluorides like KBF₄.

Electrochemical Stability: The wide stability window makes it suitable for high-voltage batteries, where other salts (e.g., KClO₄) may decompose.

Cost-Effectiveness: More affordable than specialty fluorophosphates (e.g., potassium bis(fluorosulfonyl)imide, KFSI), making it attractive for large-scale applications.

Limitations: Hygroscopicity requires careful storage to avoid moisture-induced degradation. Hydrolysis in the presence of water generates hydrofluoric acid (HF), a corrosive byproduct that can damage electrodes and container materials.

Synthesis & Quality Control

KPF₆ is produced through metathesis reactions to ensure high purity:

Reaction of Potassium Fluoride with Phosphorus Pentafluoride: KF reacts with PF₅ in anhydrous hydrogen fluoride (HF) solvent: KF + PF₅ → KPF₆. The product is isolated via crystallization and dried under vacuum.

Neutralization of Phosphoric Acid: In aqueous systems, phosphoric acid (H₃PO₄) reacts with hydrofluoric acid (HF) and potassium hydroxide (KOH), followed by precipitation: H₃PO₄ + 6HF + 3KOH → KPF₆ + 6H₂O + 2K₂HPO₄.

Quality control includes:

Ion chromatography to verify PF₆⁻ content (typically 99.0–99.5% purity for industrial grades).

X-ray diffraction (XRD) to detect crystalline impurities like KF or K₂HPO₄.

Moisture analysis (Karl Fischer) to ensure <0.1% water, critical for preventing hydrolysis in electrolyte applications.

Safety & Handling

Proper handling of KPF₆ is essential due to its fluoride content:

Toxicity: Inhalation or ingestion can cause fluoride poisoning, leading to respiratory irritation, gastrointestinal distress, or bone damage. Hydrolysis releases HF, which causes severe burns to skin and eyes.

Handling: Wear chemical-resistant gloves (nitrile or PTFE), goggles, and a dust mask when working with powders. Use in well-ventilated fume hoods to avoid HF exposure.

Storage: Keep in airtight, moisture-proof containers in a dry, cool area, separate from strong acids and bases.

Disposal: Dispose of waste as hazardous material in accordance with local regulations for fluoride compounds. Neutralize spills with calcium carbonate to form insoluble CaF₂ before cleanup.

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

Packaging & Availability

KPF₆ is available in forms tailored to industrial and research needs:

Crystalline Powder: Packaged in 1kg–25kg HDPE bottles or drums with moisture-proof liners.

Bulk Quantities: 50kg–500kg super sacks for large-scale battery production and chemical manufacturing.

High-Purity Grades: 99.9% purity variants in 100g–5kg containers for electronics and laboratory use, with ultra-low metal impurities (<10 ppm).

For technical specifications, pricing, or custom formulations, contact our team specializing in fluorinated salts for energy and chemical applications.

Health & Safety Information

 Signal Word: Danger 

Hazard Statements: H260-H228-H314 

Hazard Codes: F, C 

Precautionary Statements: P210-P231+P232-P240-P241-P260-P280-P303+P361+P353-P305+P351+P338-P370+P378-P405-P501 

Risk Codes: N/A 

Safety Statements: N/A 

Transport Information: UN 1417 4.3/PG II 

GHS Pictogram: Image,Image

Chemical Identifiers

 Linear Formula: Li-Si 

Pubchem CID: 53470676 

IUPAC Name: lithium; silicon 

SMILES: [Li].[Si] 

InchI Identifier: InChI=1S/Li.Si 

InchI Key: ZVLDJSZFKQJMKD-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.