synthesis
The first is the wet method. In the method, lithium salt is dissolved in
anhydrous hydrofluoric acid to form LiF·HF solution, and then PF5 gas
is introduced for reaction to produce lithium hexafluorophosphate
crystals. After separation and drying, the product is obtained; the
second is dry method. The method is to treat LiF with anhydrous HF to
form porous LiF, and then pass PF5 gas for reaction to obtain the
product. The third is the solvent method. The method is to make lithium
salt react with alkali metal salt, ammonium salt or organic amine salt
of fluorophosphoric acid in an organic solvent to crystallize, thereby
preparing lithium hexafluorophosphate product.
Chemical Properties
white crystalline powder
Physical properties
The isentropic bulk modulus Ks of solutions of Lithium hexafluorophosphate (LiPF6) in mixtures of cyclic (PC) and linear (EMC) carbonate solvents has been measured as a function of ternary composition and temperature. The bulk modulus was found to vary from 1–3 GPa across the composition and temperature ranges tested here, which are pertinent to conventional lithium-ion batteries
[1].
Uses
The solutions of LiPF
6 in alkyl carbonates find applications as electrolytes in lithium ion batteries and the use of high quality battery grade electrolytes having extremely low water (<15 ppm) and hydrogen fluoride (<50 ppm) contents are critical for achieving high electrochemical performance.
Uses
Lithium hexafluorophosphate (LiPF6) is the most widely used solute in liquid and gelled-type electrolytes，which has good solubility in various solvents such as PC (propylene carbonate) .
Uses
Used as an electrolyte in Li-ion batteries.Lithium hexafluorophosphate is used as an electrolyte in lithium batteries, ceramic industries and for welding electrode manufacturing. It is also used in commercial secondary batteries, prism spectrometer and x-ray monochromator. Further, it catalyzes the tetrahydropyranylation of tertiary alcohol.
Definition
ChEBI: Lithium hexafluorophosphate is an inorganic lithium salt having hexafluorophosphate(1-) as the counterion. It is an electrolyte used in lithium-ion batteries. It contains a hexafluorophosphate(1-).
General Description
Lithium hexafluorophosphate solution in ethylene carbonate and ethyl methyl carbonate is a class of electrolytic solution that can be used in the fabrication of lithium-ion batteries. Lithium-ion batteries consist of anode, cathode, and electrolyte with a charge-discharge cycle. These materials enable the formation of greener and sustainable batteries for electrical energy storage.
Flammability and Explosibility
Non flammable
Battery Materials
Lithium hexafluorophosphate (LiPF6) is the most widely used salt in the electrolytes for commercial Li-ion cells. It is commonly used as the electrolytic solution in lithium-ion rechargeable batteries. It is hydrolyzed by the small amounts of water contained in the electrolytic solution to produce fluoride and other ions.
According to the ionics studies on the limiting properties in various solvents, this excellent conductivity results from the combination of its ionic mobility and dissociation constant, although in neither category does LiPF6 stand at the most outstanding position:
Average ion mobility: LiBF4 > LiClO4 > LiPF6 > LiAsF6 > LiTf >
LiIm Dissociation constant: LiTf < LiBF4 < LiClO4 < LiPF6 < LiAsF6 < LiIm
The reversed order in the above two properties clearly demonstrates the conflicting nature of the requirements and the advantage of the well-balanced properties of LiPF6.
Lithium hexafluorophosphate is one of the most used electrolyte salt in the production of lithium ion batteries. Electrolyte Lithium Hexafluorophosphate for Lithium-ion Batteries has the ability of dissolving in binary and ternary solvents which cyclic carbonates and linear carbonates can be given as example. After lithium hexafluorophosphate dissolves in these solvents, it shows high electrolytic conductivity and thermal stability which is a desired property for lithium ion batteries.
Toxics Screening Level
The initial threshold screening level (ITSL) for lithium hexafluorophosphate (CAS #21324-40-3) is 0.1 μg/m3 based on an annual averaging time.
References
[1] Wang, A. A., Persa, D., Helin, S., Smith, K. P., Raymond, J. L., & Monroe, C. W. (2023). Compressibility of Lithium Hexafluorophosphate Solutions in Two Carbonate Solvents. Journal of Chemical & Engineering Data, 68 4, 805–812.
https://doi.org/10.1021/acs.jced.2c00711
