lithium tetrafluoroborate
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 438560736
| Name = Lithium tetrafluoroborate
| ImageFileL1 = Li+.svg
| ImageSizeL1 = 30px
| ImageFileR1 = Tetrafluoroborat-Ion.svg
| ImageSizeR1 = 120px
| IUPACName = Lithium tetrafluoroborate
| OtherNames = Borate(1-), tetrafluoro-, lithium
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 3504162
| InChI = 1/BF4.Li/c2-1(3,4)5;/q-1;+1
| InChIKey = UFXJWFBILHTTET-UHFFFAOYAL
| SMILES = [Li+].F[B-](F)(F)F
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/BF4.Li/c2-1(3,4)5;/q-1;+1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = UFXJWFBILHTTET-UHFFFAOYSA-N
| CASNo = 14283-07-9
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = AF751CNK2N
| RTECS =
| PubChem = 4298216
}}
|Section2={{Chembox Properties
| Formula = LiBF4
| MolarMass = 93.746 g/mol
| Appearance = White/grey crystalline solid
| Odor = odorless
| Density = 0.852 g/cm3 solid
| Solubility = Very soluble[http://www.gfschemicals.com/Search/MSDS/A4476MSDS.PDF GFS-CHEMICALS] {{webarchive|url=https://web.archive.org/web/20060316211507/http://www.gfschemicals.com/Search/MSDS/A4476MSDS.PDF |date=2006-03-16 }}
| MeltingPtC = 296.5
| BoilingPt = decomposes
}}
|Section3={{Chembox Structure
| Coordination =
| CrystalStruct =
| Dipole =
}}
|Section7={{Chembox Hazards
| ExternalSDS = [http://www.gfschemicals.com/Search/MSDS/A4476MSDS.PDF External MSDS]
| MainHazards = Harmful, causes burns,
hygroscopic.
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 1
}}
|Section8={{Chembox Related
| OtherAnions = Tetrafluoroborate,
| OtherCompounds = Nitrosyl 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.Xu, Kang. "Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries."Chemical Reviews 2004, volume 104, pp. 4303-418. {{doi|10.1021/cr030203g}}
Applications
Although BF4− has high ionic mobility, solutions of its Li+ salt are less conductive than other less associated salts. As an electrolyte in lithium-ion batteries, LiBF4 offers some advantages relative to the more common LiPF6. It exhibits greater thermal stability{{cite journal|author1=S. Zhang |author2=K. Xu |author3=T. Jow |title=Low-temperature performance of Li-ion cells with a LiBF4-based electrolyte|journal=Journal of Solid State Electrochemistry|year=2003|volume=7|issue=3|pages=147–151|doi=10.1007/s10008-002-0300-9|s2cid=96775286 |url=https://www.researchgate.net/publication/241026936|access-date=16 February 2014}} and moisture tolerance.{{cite journal|author1=S. S. Zhang |author2=z K. Xu |author3=T. R. Jow |name-list-style=amp |title=Study of LiBF4 as an Electrolyte Salt for a Li-Ion Battery|journal=Journal of the Electrochemical Society|year=2002|volume=149|issue=5|pages=A586–A590|doi=10.1149/1.1466857|bibcode=2002JElS..149A.586Z |url=https://www.researchgate.net/publication/244478865|access-date=16 February 2014}} 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:{{cite book |author1=Robert Brotherton |author2=Joseph Weber |author3=Clarence Guibert |author4=John Little |name-list-style=amp |section =Boron Compounds |year=2000 |title=Ullmann's Encyclopedia of Industrial Chemistry |page=10 |doi=10.1002/14356007.a04_309 |isbn=3527306730 }}
Production
LiBF4 is a byproduct in the industrial synthesis of diborane:{{cite book|last=Brauer|first=Georg|title=Handbook of Preparative Inorganic Chemistry Vol. 1, 2nd Ed|year=1963|publisher=Academic Press|location=New York|isbn=978-0121266011|page=773|url=https://books.google.com/books?id=TLYatwAACAAJ&q=Handbook+of+Preparative+Inorganic+Chemistry}}
: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):
: LiF + BF3 → LiBF4
References
{{reflist}}
{{Lithium compounds}}
{{tetrafluoroborates}}
{{inorganic-compound-stub}}
{{electrochem-stub}}