Lithium hexafluorophosphate is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the formula Li PF₆. It is a white crystalline powder.

Production

LiPF6 is manufactured by reacting

phosphorus pentachloride Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive and moist ...

with

hydrogen fluoride Hydrogen fluoride (fluorane) is an inorganic compound with the chemical formula . This colorless gas or liquid is the principal industrial source of fluorine, often as an aqueous solution called hydrofluoric acid. It is an important feedstock i ...

and

lithium fluoride Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid, that transitions to white with decreasing crystal size. Although odorless, lithium fluoride has a bitter-saline taste. Its structure is analogous to ...

:PCl₅ + LiF + 5 HF → LiPF₆ + 5 HCl Suppliers include

Targray Targray Technology International Inc., commonly referred to as Targray, is a Canadian multinational materials distributor headquartered in Kirkland, Quebec that provides commodities and supply chain solutions to the international pulses, biofuel, ...

and Morita Chemical Industries Co., Ltd

Chemistry

The salt is relatively stable thermally, but loses 50% weight at 200 °C (392 °F). It hydrolyzes near 70 °C (158 °F) according to the following equation forming highly toxic HF gas: :LiPF₆ + H₂O → HF + PF₅ + LiOH Owing to the

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

ity of the Li⁺ ions, LiPF₆ also catalyses the

tetrahydropyran Tetrahydropyran (THP) is the organic compound consisting of a saturated six-membered ring containing five carbon atoms and one oxygen atom. It is named by reference to pyran, which contains two double bonds, and may be produced from it by addi ...

ylation of

tertiary alcohol In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), whic ...

s. In

lithium-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...

, LiPF₆ reacts with Li₂CO₃, which may be catalysed by small amounts of HF: :LiPF₆ + Li₂CO₃ → POF₃ + CO₂ + 3 LiF

Application

The main use of LiPF₆ is in commercial secondary batteries, an application that exploits its high solubility in

polar aprotic solvents A polar aprotic solvent is a solvent that lacks an acidic proton and is polar. Such solvents lack hydroxyl and amine groups. In contrast to protic solvents, these solvents do not serve as proton donors in hydrogen bonding In chemistry, a hydro ...

. Specifically, solutions of lithium hexafluorophosphate in carbonate blends of

ethylene carbonate Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tran ...

dimethyl carbonate Dimethyl carbonate (DMC) is an organic compound with the formula OC(OCH3)2. It is a colourless, flammable liquid. It is classified as a carbonate ester. This compound has found use as a methylating agent and more recently as a solvent that is ...

diethyl carbonate Diethyl carbonate (sometimes abbreviated DEC) is an ester of carbonic acid and ethanol with the formula OC(OCH2CH3)2. At room temperature (25 °C) diethyl carbonate is a colorless liquid with a low flash point. Diethyl carbonate is used as ...

and/or ethyl methyl carbonate, with a small amount of one or many additives such as fluoroethylene carbonate and

vinylene carbonate Vinylene carbonate (VC) or 1,3-dioxol-2-one, is the simplest unsaturated cyclic carbonic acid ester. Vinylene carbonate can also be thought of as the cyclic carbonate of the hypothetical (''Z'')-ethene-1,2-diol. The activated double bond in this f ...

, serve as state-of-the-art

electrolytes An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon di ...

. This application also exploits the inertness of the hexafluorophosphate anion toward strong reducing agents, such as lithium metal.

References

{{Hexafluorophosphates Lithium salts Hexafluorophosphates Electrolytes