Lithium tetrafluoroborate

Lithium tetrafluoroborate is an inorganic compound with the formula LiBF₄. It is a white crystalline powder. It has been extensively tested for use in commercial secondary batteries, an application that exploits its high solubility in nonpolar solvents.^[2]

Lithium tetrafluoroborate

Names
IUPAC name Lithium tetrafluoroborate
Other names Borate(1-), tetrafluoro-, lithium
Identifiers
CAS Number	14283-07-9 Y
3D model (JSmol)	Interactive image
ChemSpider	3504162 Y
ECHA InfoCard	100.034.692
PubChem CID	4298216
UNII	AF751CNK2N Y
CompTox Dashboard (EPA)	DTXSID00884741
InChI InChI=1S/BF4.Li/c2-1(3,4)5;/q-1;+1 Y Key: UFXJWFBILHTTET-UHFFFAOYSA-N Y InChI=1/BF4.Li/c2-1(3,4)5;/q-1;+1 Key: UFXJWFBILHTTET-UHFFFAOYAL
SMILES [Li+].F[B-](F)(F)F
Properties
Chemical formula	LiBF4
Molar mass	93.746 g/mol
Appearance	White/grey crystalline solid
Odor	odorless
Density	0.852 g/cm3 solid
Melting point	296.5 °C (565.7 °F; 569.6 K)
Boiling point	decomposes
Solubility in water	Very soluble[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Harmful, causes burns, hygroscopic.
NFPA 704 (fire diamond)	1 0 1
Safety data sheet (SDS)	External MSDS
Related compounds
Other anions	Tetrafluoroborate,
Related compounds	Nitrosyl tetrafluoroborate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Applications

Although BF₄⁻ has high ionic mobility, solutions of its Li⁺ salt are less conductive than other less associated salts.^[2] As an electrolyte in lithium-ion batteries, LiBF₄ offers some advantages relative to the more common LiPF₆. It exhibits greater thermal stability^[3] and moisture tolerance.^[4] For example, LiBF₄ can tolerate a moisture content up to 620 ppm at room temperature whereas LiPF₆ readily hydrolyzes into toxic POF₃ and HF gases, often destroying the battery's electrode materials. Disadvantages of the electrolyte include a relatively low conductivity and difficulties forming a stable solid electrolyte interface with graphite electrodes.

Thermal stability

Because LiBF₄ and other alkali-metal salts thermally decompose to evolve boron trifluoride, the salt is commonly used as a convenient source of the chemical at the laboratory scale:^[5]

LiBF₄ → LiF + BF₃

Production

LiBF₄ is a byproduct in the industrial synthesis of diborane:^[5][6]

8 BF₃ + 6 LiH → B₂H₆ + 6 LiBF₄

LiBF₄ can also be synthesized from LiF and BF₃ in an appropriate solvent that is resistant to fluorination by BF₃ (e.g. HF, BrF₃, or liquified SO₂):^[5]

LiF + BF₃ → LiBF₄