Lithium hexafluorophosphate

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Lithium hexafluorophosphate
Lithium hexafluorophosphate.png
Names
IUPAC name
lithium hexafluorophosphate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.040.289 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/F6P.Li/c1-7(2,3,4,5)6;/q-1;+1 Yes check.svgY
    Key: AXPLOJNSKRXQPA-UHFFFAOYSA-N Yes check.svgY
  • 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
Appearancewhite powder
Density 2.84 g/cm3
Melting point 200 °C (392 °F; 473 K)
soluble
Hazards
GHS labelling:
GHS-pictogram-acid.svg
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).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Lithium hexafluorophosphate is an inorganic compound with the formula Li PF6. It is a white crystalline powder.

Contents

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 + 4 H2O → LiF + 5 HF + H3PO4

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 takes advantage of the inertness of the hexafluorophosphate anion toward strong reducing agents, such as lithium metal, as well as of the ability of [PF6-] to passivate the positive aluminium current collector. [9]

Related Research Articles

<span class="mw-page-title-main">Electrode</span> Electrical conductor used to make contact with nonmetallic parts of a circuit

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit. Electrodes are essential parts of batteries that can consist of a variety of materials depending on the type of battery.

<span class="mw-page-title-main">Lithium-ion battery</span> Rechargeable battery type

A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. In comparison with other commercial rechargeable batteries, Li-ion batteries are characterized by higher specific energy, higher energy density, higher energy efficiency, a longer cycle life, and a longer calendar life. Also noteworthy is a dramatic improvement in lithium-ion battery properties after their market introduction in 1991: within the next 30 years, their volumetric energy density increased threefold while their cost dropped tenfold.

<span class="mw-page-title-main">Lithium polymer battery</span> Lithium-ion battery using a polymer electrolyte

A lithium polymer battery, or more correctly lithium-ion polymer battery, is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electrolyte. Highly conductive semisolid (gel) polymers form this electrolyte. These batteries provide higher specific energy than other lithium battery types and are used in applications where weight is a critical feature, such as mobile devices, radio-controlled aircraft and some electric vehicles.

<span class="mw-page-title-main">Lithium fluoride</span> Chemical compound

Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid that transitions to white with decreasing crystal size. Its structure is analogous to that of sodium chloride, but it is much less soluble in water. It is mainly used as a component of molten salts. Partly because Li and F are both light elements, and partly because F2 is highly reactive, formation of LiF from the elements releases one of the highest energies per mass of reactants, second only to that of BeO.

<span class="mw-page-title-main">Lithium tetrafluoroborate</span> Chemical compound

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.

<span class="mw-page-title-main">Hexafluorophosphate</span> Anion with the chemical formula PF6–

Hexafluorophosphate is an anion with chemical formula of [PF6]. It is an octahedral species that imparts no color to its salts. [PF6] is isoelectronic with sulfur hexafluoride, SF6, and the hexafluorosilicate dianion, [SiF6]2−, and hexafluoroantimonate [SbF6]. In this anion, phosphorus has a valence of 5. Being poorly nucleophilic, hexafluorophosphate is classified as a non-coordinating anion.

<span class="mw-page-title-main">Sodium hexafluorophosphate</span> Chemical compound

Sodium hexafluorophosphate is an inorganic compound with the chemical formula NaPF6.

<span class="mw-page-title-main">Lithium–sulfur battery</span> Type of rechargeable battery

The lithium–sulfur battery is a type of rechargeable battery. It is notable for its high specific energy. The low atomic weight of lithium and moderate atomic weight of sulfur means that Li–S batteries are relatively light. They were used on the longest and highest-altitude unmanned solar-powered aeroplane flight by Zephyr 6 in August 2008.

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<span class="mw-page-title-main">Sodium-ion battery</span> Type of rechargeable battery

Sodium-ion batteries (NIBs, SIBs, or Na-ion batteries) are several types of rechargeable batteries, which use sodium ions (Na+) as its charge carriers. In some cases, its working principle and cell construction are similar to those of lithium-ion battery (LIB) types, but it replaces lithium with sodium as the intercalating ion. Sodium belongs to the same group in the periodic table as lithium and thus has similar chemical properties. Although, in some cases (such as aqueous Na-ion batteries) they are quite different from Li-ion batteries.

Aluminium-ion batteries are a class of rechargeable battery in which aluminium ions serve as charge carriers. Aluminium can exchange three electrons per ion. This means that insertion of one Al3+ is equivalent to three Li+ ions. Thus, since the ionic radii of Al3+ (0.54 Å) and Li+ (0.76 Å) are similar, significantly higher numbers of electrons and Al3+ ions can be accepted by cathodes with little damage. Al has 50 times (23.5 megawatt-hours m-3) the energy density of Li and is even higher than coal.

Research in lithium-ion batteries has produced many proposed refinements of lithium-ion batteries. Areas of research interest have focused on improving energy density, safety, rate capability, cycle durability, flexibility, and cost.

Lithium–silicon batteries are lithium-ion battery that employ a silicon-based anode and lithium ions as the charge carriers. Silicon based materials generally have a much larger specific capacity, for example 3600 mAh/g for pristine silicon, relative to the standard anode material graphite, which is limited to a maximum theoretical capacity of 372 mAh/g for the fully lithiated state LiC6.

<span class="mw-page-title-main">Lithium bis(trifluoromethanesulfonyl)imide</span> Chemical compound

Lithium bis(trifluoromethanesulfonyl)imide, often simply referred to as LiTFSI, is a hydrophilic salt with the chemical formula LiC2F6NO4S2. It is commonly used as Li-ion source in electrolytes for Li-ion batteries as a safer alternative to commonly used lithium hexafluorophosphate. It is made up of one Li cation and a bistriflimide anion.

An aqueous lithium-ion battery is a lithium-ion battery (Li-ion) that uses a concentrated saline solution as an electrolyte to facilitate the transfer of lithium ions between electrodes and induce an electrical current. In contrast to non-aqueous lithium-ion batteries, aqueous Li-ion batteries are nonflammable and do not pose any significant risks of explosion, because of the water-based nature of their electrolyte. They also lack the poisonous chemicals and environmental risks associated with their non-aqueous counterparts.

Calcium (ion) batteries are energy storage and delivery technologies (i.e., electro–chemical energy storage) that employ calcium ions (cations), Ca2+, as the active charge carrier. Calcium (ion) batteries remain an active area of research, with studies and work persisting in the discovery and development of electrodes and electrolytes that enable stable, long-term battery operation.

<span class="mw-page-title-main">Solid-state electrolyte</span> Type of solid ionic conductor electrolyte

A solid-state electrolyte (SSE) is a solid ionic conductor and electron-insulating material and it is the characteristic component of the solid-state battery. It is useful for applications in electrical energy storage (EES) in substitution of the liquid electrolytes found in particular in lithium-ion battery. The main advantages are the absolute safety, no issues of leakages of toxic organic solvents, low flammability, non-volatility, mechanical and thermal stability, easy processability, low self-discharge, higher achievable power density and cyclability. This makes possible, for example, the use of a lithium metal anode in a practical device, without the intrinsic limitations of a liquid electrolyte thanks to the property of lithium dendrite suppression in the presence of a solid-state electrolyte membrane. The use of a high capacity anode and low reduction potential, like lithium with a specific capacity of 3860 mAh g−1 and a reduction potential of -3.04 V vs SHE, in substitution of the traditional low capacity graphite, which exhibits a theoretical capacity of 372 mAh g−1 in its fully lithiated state of LiC6, is the first step in the realization of a lighter, thinner and cheaper rechargeable battery. Moreover, this allows the reach of gravimetric and volumetric energy densities, high enough to achieve 500 miles per single charge in an electric vehicle. Despite the promising advantages, there are still many limitations that are hindering the transition of SSEs from academia research to large-scale production, depending mainly on the poor ionic conductivity compared to that of liquid counterparts. However, many car OEMs (Toyota, BMW, Honda, Hyundai) expect to integrate these systems into viable devices and to commercialize solid-state battery-based electric vehicles by 2025.

<span class="mw-page-title-main">History of the lithium-ion battery</span> Overview of the events of the development of lithium-ion battery

This is a history of the lithium-ion battery.

Fluoride-ion batteries are rechargeable battery technology based on the shuttle of fluoride ions as ionic charge carriers.

Superconcentrated electrolytes, also known as water-in-salt or solvent-in-salt liquids, usually refer to chemical systems, which are liquid near room temperature and consist of a solvent-to-dissoved salt in a molar ratio near or smaller than ca. 4-8, i.e. where all solvent molecules are coordinated to cations, and no free solvent molecules remain. Since ca. 2010 such liquid electrolytes found several applications, primarily for batteries. In the case of lithium metal batteries and lithium-ion batteries most commonly used anions for superconcentrated electrolytes are those, that are large, asymmetric and rotationally-vibrationally flexible, such bis(trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide. Noteworthy, lithium chloride and sodium perchlorate also form water-in-salt solutions.

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.
  9. Corrosion inhibition of aluminum current collector with molybdate conversion coating in commercial LiPF6-esters electrolytes. 2021. Corrosion Sci. 190/11. S.L. Yang, S.M. Li, Y.B. Meng, M. Yu, J.H. Liu, B. Li. doi: 10.1016/j.corsci.2021.109632.