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by | Mar 16, 2018 | Hosta

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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]

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

References

  1. ^ GFS-CHEMICALS Archived 2006-03-16 at the Wayback Machine
  2. ^ a b Xu, Kang. "Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries."Chemical Reviews 2004, volume 104, pp. 4303-418. doi:10.1021/cr030203g
  3. ^ S. Zhang; K. Xu; T. Jow (2003). "Low-temperature performance of Li-ion cells with a LiBF4-based electrolyte". Journal of Solid State Electrochemistry. 7 (3): 147–151. doi:10.1007/s10008-002-0300-9. S2CID 96775286. Retrieved 16 February 2014.
  4. ^ S. S. Zhang; z K. Xu & T. R. Jow (2002). "Study of LiBF4 as an Electrolyte Salt for a Li-Ion Battery". Journal of the Electrochemical Society. 149 (5): A586–A590. Bibcode:2002JElS..149A.586Z. doi:10.1149/1.1466857. Retrieved 16 February 2014.
  5. ^ a b c Robert Brotherton; Joseph Weber; Clarence Guibert & John Little (2000). "Boron Compounds". Ullmann's Encyclopedia of Industrial Chemistry. p. 10. doi:10.1002/14356007.a04_309. ISBN 3527306730.
  6. ^ Brauer, Georg (1963). Handbook of Preparative Inorganic Chemistry Vol. 1, 2nd Ed. New York: Academic Press. p. 773. ISBN 978-0121266011.


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