How to make electrolyte with LiPF6 and what else it can make?
| Jerry Huang
Lithium hexafluorophosphate is an inorganic compound with the formula LiPF6. It is a white crystalline powder. It is used in commercial secondary batteries, an application that exploits its high solubility in non-aqueous, polar solvents. 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.
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 acidity of the Li-ions, LiPF6 also catalyses the tetrahydropyranylation of tertiary alcohols.
In lithium-ion batteries, LiPF6 reacts with Li2CO3, which may be catalysed by small amounts of HF: LiPF6 + Li2CO3 → POF3 + CO2 + 3 LiF
Furthermore, lithium hexafluorophosphate is also used in ceramic industries and for welding electrode manufacturing. It is also used in prism spectrometer and x-ray monochromator.