Lithium SeleniteCAS #: 15593-51-8

Synonyms

 dilithium selenite

Compound Formula: Li2O3Se 

Molecular Weight: 140.84 

Appearance: solid 

Melting Point: N/A 

Boiling Point: N/A 

Density: N/A 

Solubility in H2O: N/A 

Exact Mass: 141.933274 

Monoisotopic Mass: 141.933274

Product Introduction: Lithium Hexafluorophosphate (LiPF₆, CAS #: 15593-51-8)

Lithium hexafluorophosphate, with the chemical formula LiPF₆ and CAS number 15593-51-8, is a key inorganic salt widely recognized as the dominant electrolyte material in commercial lithium-ion batteries (LIBs). Composed of lithium cations (Li⁺) and hexafluorophosphate anions (PF₆⁻), this white crystalline powder exhibits exceptional ionic conductivity in organic solvents, making it indispensable for enabling efficient ion transport between battery electrodes. Its unique combination of electrochemical stability, solubility, and compatibility with electrode materials has solidified its role as a cornerstone of modern energy storage technologies, powering devices from smartphones to electric vehicles (EVs).

Chemical & Physical Properties

LiPF₆’s performance in battery systems is defined by its distinctive properties:

Solubility: Highly soluble in polar organic solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC), forming electrolytes with concentrations typically ranging from 0.8 to 1.2 M. This solubility ensures high ionic conductivity (10–15 mS/cm in optimized blends), critical for fast-charging and high-power applications.

Thermal Stability: Decomposes gradually above 80°C, with rapid decomposition occurring above 150°C, releasing toxic phosphorus pentafluoride (PF₅) and lithium fluoride (LiF). While less thermally stable than some alternatives, its decomposition products (LiF) contribute to forming a protective solid electrolyte interphase (SEI) on graphite anodes, enhancing battery safety.

Hygroscopicity: Highly hygroscopic, reacting vigorously with moisture to form hydrofluoric acid (HF), lithium phosphate (Li₃PO₄), and other byproducts. This necessitates strict moisture control during synthesis, storage, and battery assembly (typically <20 ppm water in electrolytes).

Density & Structure: Has a density of 1.50 g/cm³ and a molar mass of 151.91 g/mol, with a cubic crystal structure that ensures stability in dry conditions.

Electrochemical Window: Exhibits a stable electrochemical window up to 4.5 V vs. Li⁺/Li, compatible with most commercial cathodes (e.g., LiCoO₂, NCM, LFP), though it decomposes at higher voltages (>5 V), limiting use in next-generation high-voltage systems.

Key Applications

Lithium hexafluorophosphate (CAS 15593-51-8) is primarily utilized in energy storage, with secondary applications in specialty chemistry:

Lithium-Ion Batteries (LIBs): Serves as the primary electrolyte salt in nearly all commercial LIBs. In EV batteries, it enables energy densities exceeding 250 Wh/kg and cycle lives of 1,000+ charges, while in consumer electronics, it supports miniaturization and high-power performance. Its ability to form a stable SEI on graphite anodes reduces irreversible capacity loss, a critical factor in battery longevity.

Electrolyte Formulations: Blended with co-solvents (e.g., EC/DMC) and additives (e.g., vinylene carbonate, VC) to tailor performance. For example, adding LiPF₆ to electrolytes improves low-temperature operation (-20°C) in EVs by reducing viscosity and maintaining conductivity.

Chemical Synthesis: Acts as a fluorinating agent in organic chemistry, facilitating the introduction of fluoride groups into pharmaceutical intermediates and agrochemicals. It also serves as a catalyst in polymerization reactions, particularly for fluorinated polymers.

Research & Development: Used as a reference electrolyte in studies of new battery chemistries, including solid-state batteries and lithium-sulfur systems, providing a baseline for evaluating alternative salts.

Advantages & Limitations

LiPF₆’s dominance in batteries stems from its balanced performance, despite key limitations:

Ionic Conductivity: Outperforms early alternatives (e.g., LiClO₄, LiBF₄) in organic solvents, enabling higher power densities and faster charging—critical for EVs and power tools.

SEI Formation: Decomposition byproducts (LiF) contribute to a dense, stable SEI layer on anodes, preventing electrolyte further decomposition and extending cycle life.

Cost-Effectiveness: Scalable synthesis and mature production processes make it more affordable than specialty salts (e.g., LiFSI, LiTFSI), supporting mass adoption of LIBs.

Limitations: High hygroscopicity increases manufacturing complexity and costs due to moisture control requirements. Thermal decomposition at elevated temperatures poses safety risks in battery thermal runaway scenarios. Its incompatibility with high-voltage cathodes (>4.5 V) drives research into alternatives for next-generation batteries.

Synthesis & Quality Control

LiPF₆ is produced via specialized processes to ensure high purity:

Direct Reaction: Lithium fluoride (LiF) reacts with phosphorus pentafluoride (PF₅) in anhydrous hydrogen fluoride (HF) solvent: LiF + PF₅ → LiPF₆. The product is isolated by crystallizing from HF and drying under vacuum to remove residual solvent.

Purification: Crude LiPF₆ undergoes recrystallization from anhydrous organic solvents (e.g., EC) to reduce impurities (e.g., LiF, PF₅, metal ions) to <100 ppm, critical for preventing battery performance degradation.

Quality control includes:

Ion chromatography to verify PF₆⁻ content (typically 99.9% purity for battery grades).

Inductively coupled plasma mass spectrometry (ICP-MS) to detect trace metals (Fe, Na, K <1 ppm).

Karl Fischer titration to ensure moisture content <50 ppm, as excess water triggers HF formation.

Safety & Handling

Due to its reactivity with moisture and toxicity, LiPF₆ requires rigorous safety protocols:

Toxicity: Inhalation of dust or contact with moisture releases HF, causing severe burns to skin, eyes, and respiratory tracts. Chronic exposure to fluoride ions may damage bones and teeth.

Handling: Use in dry, inert gas-purged glove boxes or fume hoods with moisture levels <1% RH. Wear PTFE gloves, splash goggles, and a respirator rated for HF exposure.

Storage: Keep in airtight, moisture-proof containers (e.g., stainless steel drums) in a cool, dry area, separated from water, acids, and bases.

Spill Response: Neutralize spills with calcium carbonate (CaCO₃) to form insoluble CaF₂, avoiding water, which accelerates HF release. Dispose of waste as hazardous material per local regulations (e.g., EPA RCRA in the U.S.).

Refer to the product’s Safety Data Sheet (SDS) for emergency procedures, including first aid for HF exposure (use calcium gluconate gel).

Packaging & Availability

LiPF₆ is supplied in formats tailored to battery manufacturing and research:

Battery Grade: 20kg–50kg sealed steel drums with moisture barriers, suitable for large-scale electrolyte production.

Research Grade: 100g–5kg bottles in argon-purged aluminum bags, ensuring ultra-low moisture content (<10 ppm) for laboratory use.

Electrolyte Solutions: Pre-dissolved in solvent blends (e.g., 1.0 M in EC/DMC) in 1L–20L containers, used in small-batch battery assembly.

Global production is dominated by companies in China, Japan, and South Korea, with annual capacity exceeding 100,000 tons to meet EV and energy storage demand. High-purity grades (99.99%) with ultra-low metal impurities are available for advanced research.

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

Health & Safety Information

 Signal Word: N/A 

Hazard Statements: N/A 

Hazard Codes: N/A 

Risk Codes: N/A 

Safety Statements: N/A 

Transport Information: N/A

Chemical Identifiers 

Linear Formula: Li2SeO3 

Pubchem CID: 167310 

MDL Number: N/A 

EC No.: 239-666-4

IUPAC Name: N/A 

Beilstein/Reaxys No.: N/A 

SMILES: [Li+].[Li+].[O-][Se]([O-])=O 

InchI Identifier: InChI=1S/2Li.H2O3Se/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2 

InchI Key: SMVMOIXTOKYXAN-UHFFFAOYSA-L

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.