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 chemi ...
with the formula
Li PF6. It is a white crystalline powder.
Production
LiPF6 is manufactured by reacting
phosphorus pentachloride with
hydrogen fluoride 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 ...
:PCl
5 + LiF + 5 HF → LiPF
6 + 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, biofue ...
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:
:LiPF
6 + H
2O → HF + PF
5 + 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, LiPF
6 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 alcohols.
In
lithium-ion batteries, LiPF
6 reacts with Li
2CO
3, which may be catalysed by small amounts of HF:
:LiPF
6 + Li
2CO
3 → POF
3 + CO
2 + 3 LiF
Application
The main use of LiPF
6 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,
dimethyl carbonate,
diethyl carbonate and/or ethyl methyl carbonate, with a small amount of one or many additives such as fluoroethylene carbonate and
vinylene carbonate, serve as state-of-the-art
electrolytes in
lithium-ion batteries.
This application also exploits the inertness of the hexafluorophosphate anion toward strong reducing agents, such as lithium metal.
References
{{Hexafluorophosphates
Lithium salts
Hexafluorophosphates
Electrolytes