Lithium hexafluorophosphate
Lithium hexafluorophosphate.png
Names
IUPAC name
lithium hexafluorophosphate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.040.289 Edit this at Wikidata
UNII
  • InChI=1S/F6P.Li/c1-7(2,3,4,5)6;/q-1;+1 checkY
    Key: AXPLOJNSKRXQPA-UHFFFAOYSA-N checkY
  • InChI=1/F6P.Li/c1-7(2,3,4,5)6;/q-1;+1
    Key: AXPLOJNSKRXQPA-UHFFFAOYAJ
  • [Li+].F[P-](F)(F)(F)(F)F
Properties
LiPF6
Molar mass 151.905 g/mol
Appearance white powder
Density 2.84 g/cm3
Melting point 200 °C (392 °F; 473 K)
soluble
Hazards
GHS labelling:
GHS05: Corrosive
Danger
H314
P280, P305+P351+P338, P310
Flash point Non-flammable
Safety data sheet (SDS) External MSDS
Related compounds
Other anions
Lithium tetrafluoroborate
Other cations
Sodium hexafluorophosphate
Potassium hexafluorophosphate
Ammonium hexafluorophosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Lithium hexafluorophosphate is an inorganic compound with the formula LiPF6. It is a white crystalline powder.

Production

LiPF6 is manufactured by reacting phosphorus pentachloride with hydrogen fluoride and lithium fluoride[1] [2]

PCl5 + LiF + 5 HF → LiPF6 + 5 HCl

Suppliers include Targray and Morita Chemical Industries Co., Ltd

Chemistry

The salt is relatively stable thermally, but loses 50% weight at 200 °C (392 °F). It hydrolyzes near 70 °C (158 °F)[3] 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.[4]

In lithium-ion batteries, LiPF6 reacts with Li2CO3, which may be catalysed by small amounts of HF:[5]

LiPF6 + Li2CO3 → POF3 + CO2 + 3 LiF

Application

The main use of LiPF6 is in commercial secondary batteries, an application that exploits its high solubility in polar aprotic 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.[6][7][8] This application also exploits the inertness of the hexafluorophosphate anion toward strong reducing agents, such as lithium metal.

References

  1. ^ Dunn, JB; Gaines, L; Barnes, M; Sullivan, J; Wang M (Sep 2014). "Material and Energy Flows in the Materials Production, Assembly, and End-of-Life Stages of the Automotive Lithium-Ion Battery Life Cycle". p. 28. Retrieved 5 December 2020.
  2. ^ O'Leary, Brian (11 May 2011). "High-Volume Manufacturing of LiPF6, A Critical Lithium-ion Battery Material" (PDF). p. 5. Retrieved 5 December 2020.
  3. ^ Xu, Kang (October 2004). "Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries". Chemical Reviews. 104 (10): 4303–4418. doi:10.1021/cr030203g. PMID 15669157. S2CID 33074301.
  4. ^ Nao Hamada; Sato Tsuneo (2004). "Lithium Hexafluorophosphate-Catalyzed Efficient Tetrahydropyranylation of Tertiary Alcohols under Mild Reaction Conditions". Synlett (10): 1802–1804. doi:10.1055/s-2004-829550.
  5. ^ Bi, Yujing; Wang, Tao; Liu, Meng; Du, Rui; Yang, Wenchao; Liu, Zixuan; Peng, Zhe; Liu, Yang; Wang, Deyu; Sun, Xueliang (2016). "Stability of Li2CO3 in cathode of lithium ion battery and its influence on electrochemical performance". RSC Advances. 6 (23): 19233–19237. Bibcode:2016RSCAd...619233B. doi:10.1039/C6RA00648E. ISSN 2046-2069.
  6. ^ Goodenough, John B.; Kim, Youngsik (9 February 2010). "Challenges for Rechargeable Li Batteries". Chemistry of Materials. 22 (3): 587–603. doi:10.1021/cm901452z.
  7. ^ Qian, Yunxian; Hu, Shiguang; Zou, Xianshuai; Deng, Zhaohui; Xu, Yuqun; Cao, Zongze; Kang, Yuanyuan; Deng, Yuanfu; Shi, Qiao; Xu, Kang; Deng, Yonghong (2019). "How electrolyte additives work in Li-ion batteries". Energy Storage Materials. 20: 208–215. doi:10.1016/j.ensm.2018.11.015. ISSN 2405-8297. S2CID 139865927.
  8. ^ Jow, T. Richard; Borodin, Oleg; Ue, Makoto; Xu, Kang (2014). Electrolytes for Lithium and Lithium-Ion Batteries. Springer: New York. ISBN 9781493903023.