Lithium hexafluorophosphate LiPF6

spore: profile
id: lithium-hexafluorophosphate
spore_version: 0.2
family: lithium
name: Lithium hexafluorophosphate
abbreviation: LiPF6
role: conducting salt (electrolyte)
category: energy
type: electrolytes
summary: |
  Lithium hexafluorophosphate (LiPF6) is the lithium salt dissolved in the organic carbonate liquids of most lithium-ion cells, where it carries lithium ions between the electrodes. A 1.0 M solution in ethylene carbonate and dimethyl carbonate (1:1 by weight) conducts about 10.8 to 12.9 mS/cm at 20 to 30 degC, but conductivity collapses below 0.1 mS/cm under -20 degC in a similar commercial mixture. The salt is unstable: dry, it splits into LiF and PF5 gas, and with water it gives HF and POF3, which is why cells that burn can release 20 to 200 mg of HF per Wh.
best_for: A conductive, widely used salt for carbonate electrolytes (10.8 to 12.9 mS/cm for a 1.0 M solution at 20 to 30 degC)
weakest_at: 'Heat and moisture: it decomposes from about 380 K dry, earlier with water, and gives off toxic HF'
identity:
  formula: LiPF6
  cas: 21324-40-3
  source: pubchem-lipf6
  where: Compound record CID 23688915 (formula F6LiP, CAS 21324-40-3); the supplier safety data sheet (Stanford Advanced Materials) section 1 gives the same CAS
tags:
  environments: []
  stresses:
    - extreme-cold
    - extreme-heat
    - thermal-cycling
  applications:
    - batteries
properties:
  - benchmark: molar_mass
    label: Molar mass
    value: 151.9
    unit: g/mol
    scope: material
    conditions:
      basis: computed from the formula F6LiP, not measured
      computed_by: PubChem 2.2
    method: Value computed by PubChem from the molecular formula
    status: calculated
    source: pubchem-lipf6
    where: Computed Properties > Molecular Weight
  - benchmark: density
    label: Density of the solid salt
    value: 1.5
    unit: g/cm3
    scope: material
    conditions:
      temperature: 25 degC
      form: solid salt
      listing: PAC Chemical Database (US Department of Energy), reproduced in PubChem
    method: Value listed in a database record (measurement method not stated)
    status: ground
    note: The Stanford Advanced Materials safety data sheet also lists 1.5 g/cm3 at 20 degC. Both are one-digit values.
    source: pubchem-lipf6
    where: Experimental Properties > Density
  - benchmark: melting_point
    label: Melting point (with decomposition)
    value: 200
    unit: degC
    scope: material
    conditions:
      form: powder
      marked: (dec), meaning it decomposes
      atmosphere: not stated
    method: Value listed in the supplier safety data sheet
    status: ground
    note: PubChem also lists 200 degC (from the DOE PAC database). The thermogravimetry papers below find dry LiPF6 already splitting into LiF and PF5 at far lower temperatures (380 K, about 107 degC, in Yang et al.), so 200 degC is not a stability limit.
    source: sa-sds
    where: Section 9, Melting point/Melting range
  - benchmark: salt_stability_limit_dry
    label: Highest temperature at which dry LiPF6 is stable
    value: 380
    unit: K
    bound: lower
    scope: material
    conditions:
      sample: neat LiPF6 salt
      atmosphere: dry inert carrier gas, water below 10 ppm
      method_rate: TGA at 10 K/min
      decomposition_product: LiF solid and PF5 gas (LiPF6 to LiF + PF5)
    method: Thermogravimetric analysis with on-line FTIR of the gases
    status: ground
    note: The abstract states the salt is stable up to 380 K. In the text, dry isothermal runs showed no mass change in 1 h at 343 K or 363 K, and 3.2% mass loss after one more hour at 383 K. FTIR showed PF5 as the only gas-phase product from 380 to 540 K.
    source: yang2006
    where: Abstract; Results (TG of LiPF6 at isothermal conditions, Fig. 4)
  - benchmark: mass_loss_383k_dry_1h
    label: Mass lost by dry LiPF6 after one hour at 383 K
    value: 3.2
    unit: '% of initial mass'
    scope: material
    conditions:
      sample: neat LiPF6 salt
      atmosphere: dry gas, water below 10 ppm
      history: no mass change in 1 h at 343 K or in 1 h at 363 K before this hour
      temperature: 383 K
    method: Isothermal thermogravimetry
    status: ground
    note: The paper reads the isothermal onset of about 383 K as agreeing with the non-isothermal run. Mass-loss reporting error in the paper is +/-1%.
    uncertainty: +/-1% mass-loss reporting error stated in the Experimental section
    source: yang2006
    where: Results, isothermal TG paragraph (Fig. 4); Experimental
  - benchmark: salt_onset_dry_tgams
    label: Decomposition onset of dry LiPF6 (TGA-MS)
    value: 165
    unit: degC
    scope: material
    conditions:
      sample: about 150 mg LiPF6 in a sapphire crucible, dried at 70 degC for 18 h
      protocol: 1 h hold at 120 degC in dry Ar, then ramp of 10 K/min to 350 degC
      detection: mass loss and mass-spectrometer gas signals
    method: Thermogravimetry coupled to mass spectrometry
    status: ground
    note: Mass loss was 83%, equal to the theoretical loss for full conversion to LiF (Eq. 1 of the paper). The paper also states, from the literature, that dry LiPF6 thermal dissociation occurs between 100 and 200 degC depending on conditions, and the 165 degC figure is higher than the 380 K (about 107 degC) of Yang et al., so the onset depends on the pre-treatment, holds and detection.
    source: solchenbach2018
    where: Results, Thermal decomposition of dry and wet LiPF6 (Fig. 2); Conclusions
  - benchmark: salt_onset_wet_tgams
    label: Decomposition onset of water-exposed LiPF6 (TGA-MS)
    value: 90
    unit: degC
    scope: material
    conditions:
      sample: LiPF6 pre-exposed for 1 h to water-saturated Ar (dew point about 20 degC), mass gain about 24%
      protocol: ramp of 10 K/min to 350 degC
      product: POF3 only, no PF5 signal
    method: Thermogravimetry coupled to mass spectrometry
    status: ground
    note: About 75 degC below the dry salt. Final mass loss was only 49% against 83% for dry LiPF6, which the authors attribute to formation of LiPO2F2. HF could not be traced in their set-up because its mass overlaps with argon.
    source: solchenbach2018
    where: Results, Thermal decomposition of dry and wet LiPF6 (Fig. 3); Conclusions
  - benchmark: onset_shift_300ppm_water
    label: Lowering of the decomposition onset by 300 ppm water vapour
    value: 27
    unit: K
    scope: material
    conditions:
      sample: neat LiPF6 salt
      carrier_gas: argon with 300 ppm water vapour, against dry gas below 10 ppm
      rate: 10 K/min
    method: Derivative thermogravimetry (DTG) onset, with on-line FTIR showing HF and POF3 before PF5
    status: ground
    note: The paper states the onset drops by ca. 27 K and concludes that the water reaction forms POF3 and HF directly, LiPF6 + H2O to LiF + POF3 + 2HF.
    source: yang2006
    where: Results, TG of neat LiPF6 (Fig. 1, inset); FTIR section (Fig. 3 inset)
  - benchmark: residual_mass_lif_dry
    label: Mass remaining after dry LiPF6 decomposed
    value: 17.1
    unit: '% of initial mass'
    scope: material
    conditions:
      sample: neat LiPF6 salt
      atmosphere: dry carrier gas
      end_of_run: about 530 K, 10 K/min
    method: Thermogravimetry
    status: ground
    note: The authors say this matches the calculated LiF to LiPF6 mass ratio for LiPF6 giving LiF + PF5.
    source: yang2006
    where: Results, FTIR and TG section (text after Fig. 3)
  - benchmark: hydrolysis_none_seen_to_temp
    label: Highest temperature with no detected hydrolysis of LiPF6 in a wet EC electrolyte
    value: 40
    unit: degC
    bound: lower
    scope: material
    conditions:
      electrolyte: 1.5 M LiPF6 in ethylene carbonate with 5000 ppm H2O
      steps: 10, 25, 40, 60 degC for 3 h each, then 80 degC for 12 h
      detection: online mass spectrometry of POF3 and CO2
    method: Online electrochemical mass spectrometry (OEMS) of the headspace
    status: ground
    note: At 60 degC and above POF3 was seen (below 2000 ppm) and CO2 above 12000 ppm at 60 and 80 degC. The abstract concludes the kinetics for the hydrolysis of LiPF6 with water at room temperature are too slow to be detectable, and that acidic species made by solvent oxidation, not water alone, shift PF6- to PF5 and HF. 5000 ppm methanesulfonic acid gave about 1000 ppm POF3 at 25 degC.
    source: solchenbach2018
    where: Abstract; Results, Fig. 7b and 7c
  - benchmark: ionic_conductivity
    label: Ionic conductivity, 1.0 M LiPF6 in EC:DMC (1:1 w:w)
    value: 10.8
    value_high: 12.9
    bound: range
    unit: mS/cm
    scope: material
    conditions:
      solvent: 'ethylene carbonate : dimethyl carbonate 1:1 by weight'
      concentration: 1.0 M LiPF6
      temperature: 20 to 30 degC
      cell: Pt microelectrode conductivity cell (rhd TSC 1600), cell constant 20 +/- 0.2 per cm
    method: Impedance spectroscopy (85 kHz to 1 kHz, 100 mV)
    status: ground
    uncertainty: error bars of 3% for the cell constant, filling and fitting (Fig. 8 caption)
    note: The paper compares this with 11.9 mS/cm at 25 degC from Farkhondeh et al. and with the BASF specification sheet for LP30 and LP57 (Supporting Information Fig. S2), and finds good agreement. This is a research-grade electrolyte, not a space-qualified one.
    source: landesfeind2019
    where: Results, Concentration and temperature dependent description of kappa (page A3090); Fig. 8a
  - benchmark: ionic_conductivity_50c
    label: Ionic conductivity, 1.0 M LiPF6 in EC:DMC (1:1 w:w), warm
    value: 17
    unit: mS/cm
    scope: material
    conditions:
      solvent: EC:DMC 1:1 by weight
      concentration: 1.0 M LiPF6
      temperature: +50 degC
      reading: stated as about 17 mS/cm, the top of the range for all electrolytes measured
    method: Impedance spectroscopy in a Pt microelectrode conductivity cell
    status: ground
    note: The paper writes the figure with a tilde (about 17 mS/cm). Highest conductivities occur between about 0.75 M at -10 degC and about 1 M at +50 degC.
    source: landesfeind2019
    where: Results, text on conductivity (page A3090); Fig. 8a
  - benchmark: ionic_conductivity_3m_cold
    label: Ionic conductivity, 3.0 M LiPF6 at -10 degC (lowest of the measured range)
    value: 0.5
    unit: mS/cm
    scope: material
    conditions:
      concentration: 3.0 M LiPF6
      temperature: '-10 degC'
      solvents: the paper states this as the low end of the range for its three solvent mixtures (EC:DMC, EC:EMC, EMC:FEC); the exact solvent is not named in the sentence
    method: Impedance spectroscopy in a Pt microelectrode conductivity cell
    status: ground
    note: Shows that more salt does not mean more conductivity. Highest conductivity sits near 0.75 to 1 M.
    source: landesfeind2019
    where: Results, text on conductivity (page A3090); Fig. 8
  - benchmark: conductivity_peak_concentration
    label: Salt concentration giving the highest conductivity (EC:DMC and EC:EMC)
    value: 0.75
    value_high: 1
    bound: range
    unit: mol/L
    scope: material
    conditions:
      solvents: EC:DMC 1:1 w:w and EC:EMC 3:7 w:w
      temperature: about 0.75 M at -10 degC, about 1 M at +50 degC
      range_tested: 0.1 to 3.0 M LiPF6
    method: Impedance spectroscopy in a Pt microelectrode conductivity cell
    status: ground
    note: The EC-free electrolyte (EMC:FEC 19:1 w:w) peaked at higher concentration, about 1.25 M at -10 degC to about 1.6 M at +50 degC.
    source: landesfeind2019
    where: Results, text on conductivity (page A3090); Fig. 8
  - benchmark: conductivity_cold_upper_bound
    label: Ionic conductivity of a commercial 1 M LiPF6 EC/DMC electrolyte below -20 degC
    value: 0.1
    unit: mS/cm
    bound: upper
    scope: material
    conditions:
      electrolyte: commercial reference electrolyte, 1 M LiPF6 in EC/DMC 1:1 (the paper's Com. Ele.)
      temperature: below -20 degC
      sweep: '-90 to 70 degC in 10 degC steps'
    method: DC conductivity from a broadband dielectric/impedance spectrometer (Novocontrol)
    status: ground
    note: The text only gives the upper bound ('generally lower than 0.1 mS/cm'); exact points are in Fig. 1A and were not read. Read through a web summary of the open article, not from the PDF.
    source: zhao2020
    where: Results, Regulating Kinetics of Electrolytes by the Solvent; Fig. 1A; Methods
  - benchmark: min_service_temp
    label: Lowest temperature in NASA/JPL low-temperature cell tests with 1.0 M LiPF6 electrolytes
    value: -70
    unit: degC
    scope: cell
    conditions:
      electrolyte: 1.0 M LiPF6 in five alkyl-carbonate/ester mixtures (1EC+1EMC+8MB, 8EB, 8MP, 1EC+1EMC+8EV, 1EC+9EMC by volume)
      cell: carbon anode, LiNi0.8Co0.2O2 cathode
      statement: improved performance in cells at temperatures as low as -70 degC
    method: Low-temperature electrical performance tests of laboratory Li-ion cells, as summarised in a NASA Tech Brief
    status: ground
    note: A cell result, not a property of the salt. The brief says the cells with the MB and MP mixtures performed best. No capacity or rate figures are given in the brief. Not a flight result.
    source: nasa-techbrief-2005
    where: Tech Brief 'Ester-Based Electrolytes for Low-Temperature Li-Ion Cells' (NPO-41097), page 25
  - benchmark: hf_emitted_in_cell_fire
    label: Hydrogen fluoride released when commercial Li-ion cells burned
    value: 20
    value_high: 200
    bound: range
    unit: mg/Wh of nominal energy
    scope: cell
    conditions:
      cells: seven types of commercial Li-ion batteries, all electrolytes contained LiPF6
      state_of_charge: 0 to 100% (several SOC values)
      test: fire test with real-time FTIR, cross-checked with gas-washing bottles
      per_type_ranges: type A 15-25, type B 150-198, type G 15 mg/Wh in Table 2
    method: Fire tests of cells with FTIR and gas-washing measurements of HF
    status: ground
    note: HF can also come from fluorine in binders, separators and flame retardants, not only LiPF6; the paper says the electrolyte is typically the primary fluorine source. The abstract gives the range as 20 to 200 mg/Wh, while Table 2 rows start lower (as low as 12 mg/Wh for type D).
    source: larsson2017
    where: Abstract; Table 2; Results (Fig. 2a)
  - benchmark: pof3_emitted_in_cell_fire
    label: Phosphoryl fluoride (POF3) released in some cell fire tests
    value: 15
    value_high: 22
    bound: range
    unit: mg/Wh of nominal energy
    scope: cell
    conditions:
      cells: commercial Li-ion cells containing LiPF6
      test: fire tests with FTIR, measured in some tests only
    method: Fire tests with FTIR
    status: ground
    source: larsson2017
    where: Abstract; Results (POF3 paragraph)
corrosion:
  - environment: Water and moisture
    headline: Water makes LiPF6 give off HF and POF3; in a cell electrolyte at room temperature this reaction was too slow to detect.
    effect: The supplier safety data sheet names water and moisture as incompatible, says the product is moisture sensitive and lists hydrogen fluoride as a hazardous decomposition product. In thermogravimetry, 300 ppm water vapour lowered the decomposition onset by ca. 27 K and gave HF and POF3. In a wet 1.5 M LiPF6 in ethylene carbonate electrolyte with 5000 ppm H2O, no POF3 was seen up to 40 degC, but acids (methanesulfonic acid) quickly pushed PF6- toward PF5 and HF.
    rating: moderate
    conditions:
      sds: Stanford Advanced Materials, revised 17 November 2022, section 10
      thermogravimetry: 300 ppm water vapour, 10 K/min
      electrolyte_test: 5000 ppm H2O in 1.5 M LiPF6 in EC, up to 80 degC
    source: sa-sds
    where: Sections 7 and 10; Yang et al. Abstract and Fig. 1; Solchenbach et al. Fig. 7
  - environment: Acids and oxidising agents
    headline: The safety data sheet lists acids, oxidising agents and heat as incompatible.
    effect: Section 10 lists acids, water/moisture, oxidising agents and heat as incompatible materials, and the salt reacts with strong oxidising agents. No rate or test is given.
    rating: unknown
    conditions:
      basis: supplier safety data sheet, no quantitative test
    source: sa-sds
    where: Section 10
risks:
  hazards:
    - text: 'PubChem aggregates 296 reports from 22 ECHA C&L Inventory notifications: signal word Danger. H314 (causes severe skin burns and eye damage) is given by 100% of notifiers, H372 (damage to organs through prolonged or repeated exposure) by 81.8%, H301 (toxic if swallowed) by 79.7%, H318 (serious eye damage) by 69.9%, H302 (harmful if swallowed) by 20.3% and H311 (toxic in contact with skin) by 16.2%. The classifications differ between notifiers.'
      ghs:
        - H314
        - H372
        - H301
        - H318
        - H302
        - H311
      source: pubchem-lipf6
      where: Safety and Hazards > Hazards Identification > GHS Classification (aggregated ECHA C&L data)
    - text: The Stanford Advanced Materials safety data sheet (revised 17 November 2022) classifies it as Acute Tox. 3 (H311), Skin Corr. 1B (H314), Eye Dam. 1 (H318) and Acute Tox. 4 (H302), signal word Danger, with pictograms GHS05 and GHS06. It says swallowing causes strong corrosion of mouth and throat with danger of perforation, and skin contact is dangerous through absorption. It lists no LD50/LC50 data and, unlike PubChem, 'No effects known' for repeated-exposure organ toxicity.
      ghs:
        - H302
        - H311
        - H314
        - H318
      source: sa-sds
      where: Sections 2 and 11
    - text: The salt is not flammable but if involved in a fire it releases hydrogen fluoride, phosphorus oxides and lithium oxide. Firefighters need a self-contained respirator and a fully protective impervious suit.
      ghs: []
      source: sa-sds
      where: Sections 5 and 10
  failure_risks:
    - mode: Hydrogen fluoride and POF3 release when a cell burns
      trigger: Fire of a commercial Li-ion cell whose electrolyte contains LiPF6
      consequence: Fire tests of seven commercial cell types measured 20 to 200 mg of HF per Wh of nominal capacity, plus 15 to 22 mg/Wh of POF3 in some tests. The authors say fluoride gas emission can pose a serious toxic threat, notably for large battery packs and confined spaces such as a spacecraft.
      severity: high
      source: larsson2017
      where: Abstract; Introduction; Table 2
    - mode: Thermal decomposition of the salt
      trigger: Heating the dry salt to about 380 K or more, or earlier if water or acid is present
      consequence: LiPF6 splits into solid LiF and PF5 gas; with 300 ppm water the onset falls by ca. 27 K and HF and POF3 form first. In thermogravimetry on wet salt the onset was about 90 degC.
      severity: moderate
      source: yang2006
      where: Abstract; Results; Solchenbach et al. Fig. 3
    - mode: Acid-driven breakdown inside the electrolyte
      trigger: Acidic species, for example from oxidation of ethylene carbonate or an added strong acid
      consequence: Protons shift PF6- toward PF5 and HF; 5000 ppm methanesulfonic acid in EC with 1.5 M LiPF6 gave POF3 near 1000 ppm at 25 degC and about 11000 ppm at 80 degC.
      severity: moderate
      source: solchenbach2018
      where: Results, Fig. 7b and Abstract
    - mode: Loss of conductivity when cold
      trigger: Cooling a 1 M LiPF6 EC/DMC electrolyte below -20 degC
      consequence: The commercial reference electrolyte conducted generally less than 0.1 mS/cm below -20 degC, far below the 10.8 to 12.9 mS/cm of a similar 1.0 M solution at 20 to 30 degC.
      severity: moderate
      source: zhao2020
      where: Results, Fig. 1A
  side_effects:
    - text: PF5 produced by dry decomposition reacts with trace water to give POF3, and the authors note PF5 reacts with water in the carrier gas in their set-up, so the gases seen depend on how dry the test was.
      affects: Interpretation of decomposition measurements
      source: yang2006
      where: Results (FTIR section, text before reaction [1])
    - text: In an online mass-spectrometry cell all PF5 was detected as POF3, which the authors treat as an analysis effect, so earlier PF5-versus-POF3 assignments may be affected.
      affects: Reading of gas-analysis data
      source: solchenbach2018
      where: Results (Figs. 4 and 5)
  handling:
    - text: Handle under dry protective gas, keep the container tightly sealed, store under dry inert gas away from water, moisture, heat, acids and oxidising agents. The sheet marks it moisture sensitive and says to refrigerate.
      source: sa-sds
      where: Section 7
    - text: Work in a properly operating chemical fume hood (average face velocity at least 100 feet per minute); use impervious gloves, for example nitrile rubber 0.11 mm with a stated breakthrough of 480 minutes.
      source: sa-sds
      where: Section 8
    - text: A Sony product safety data sheet for the US18650VT cell (23 March 2007) lists only 'Lithium Salt' in organic solvent as electrolyte, states the contents of an opened cell can irritate lungs, skin and eyes, and advises not to open, crush or burn the cell.
      source: sony-sds
      where: Sections hazardous ingredients, health hazard data, handling
  mitigations:
    - text: Take off contaminated clothing at once and rinse skin with water; if in eyes rinse cautiously with water for several minutes and remove contact lenses if easy; store locked up; use a neutralising agent for spills and keep it out of drains.
      source: sa-sds
      where: Sections 2 and 6 (P303+P361+P353, P305+P351+P338, P361, P405)
uses:
  - application: batteries
    device: Conducting salt in the electrolytes of commercial lithium-ion cells
    example: The LBNL study states LiPF6 is the most widely used salt in the electrolytes for commercial Li-ion cells, and every one of the seven commercial cell types in the Larsson fire study had a LiPF6 electrolyte.
    source: yang2006
    where: Introduction; Larsson et al. Results
  - application: batteries
    device: NASA/JPL laboratory Li-ion cells for low-temperature operation
    example: JPL tested 1.0 M LiPF6 in five carbonate/ester solvent mixtures in cells with carbon anodes and LiNi0.8Co0.2O2 cathodes down to -70 degC (ground tests only).
    source: nasa-techbrief-2005
    where: Tech Brief NPO-41097, page 25
documents:
  - title: 'PubChem compound record: Lithium hexafluorophosphate (CID 23688915)'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23688915
    year: 2026
  - title: 'Stanford Advanced Materials safety data sheet: Lithium Hexafluorophosphate'
    type: sds
    url: https://samaterials.com/tds/1697120063-2019-lithium-hexafluorophosphate-powder-sds.pdf
    year: 2022
  - title: Sony Energy Devices product safety data sheet, US18650VT (23 March 2007)
    type: sds
    url: https://support.blackanddecker.com/hc/en-us/article_attachments/360012464837
    year: 2007
  - title: Thermal Stability of LiPF6 Salt and Li-ion Battery Electrolytes Containing LiPF6 (LBNL)
    type: paper
    url: https://www.osti.gov/biblio/898281
    year: 2006
  - title: Quantification of PF5 and POF3 from Side Reactions of LiPF6 in Li-Ion Batteries (open access)
    type: paper
    url: https://iopscience.iop.org/article/10.1149/2.0481813jes
    year: 2018
  - title: Temperature and Concentration Dependence of the Ionic Transport Properties of Lithium-Ion Battery Electrolytes (open access)
    type: paper
    url: https://iopscience.iop.org/article/10.1149/2.0571912jes
    year: 2019
  - title: Toxic fluoride gas emissions from lithium-ion battery fires (open access)
    type: paper
    url: https://www.nature.com/articles/s41598-017-09784-z
    year: 2017
  - title: 'NASA Tech Briefs, December 2005: Ester-Based Electrolytes for Low-Temperature Li-Ion Cells'
    type: report
    url: https://ntrs.nasa.gov/citations/20110016439
    year: 2005
  - title: USGS Mineral Commodity Summaries 2026, Fluorspar
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    year: 2026
  - title: NIST Atomic Weights and Isotopic Compositions (lithium, phosphorus, fluorine)
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Li&ascii=html&isotype=some
  - title: Lithium hexafluorophosphate (Wikipedia)
    type: database
    url: https://en.wikipedia.org/wiki/Lithium_hexafluorophosphate
gaps:
  - The Sony safety data sheet that lists LiPF6 at 2% was not found. The Sony sheet that was opened (US18650VT, 23 March 2007) names only 'Lithium Salt' and gives no percentage, so the 2% figure is not entered.
  - No ECHA registration dossier or harmonised classification was opened; GHS rests on PubChem's aggregate of ECHA notifications and one supplier safety data sheet, which disagree on repeated-exposure toxicity (H372).
  - Acute toxicity figures (LD50/LC50) are not given in the supplier sheet ('No data'); none were found.
  - Exact conductivity values at 25 degC for 1.0 M LiPF6 in EC:EMC 3:7 were only shown as a literature curve; Table II fit parameters of Landesfeind and Gasteiger were not entered.
  - Conductivity of LiPF6 in the solvent blends used on spacecraft (for example the JPL ester mixtures) was not found; the NASA Tech Brief gives no conductivity or capacity numbers.
  - No vacuum outgassing, radiation-dose, or flight data for LiPF6 itself was found; every number is ground-laboratory.
  - The Netzsch application note on electrolyte thermal stability and a DFT preprint arguing that POF3 forms mainly via Li2CO3 were only seen as search snippets, not opened, and are not used.
  - Solubility in water or in carbonate solvents (g per 100 g) and vapour pressure were not found in an opened source (the safety data sheet says only 'soluble' in water).
  - Hydrolysis rates at elevated temperature were not quantified beyond the POF3 and CO2 levels read from Solchenbach et al. Fig. 7.
  - The Zhao et al. conductivity bound and the Solchenbach et al. values were read through a web summary of the open article, not from a downloaded PDF (the publisher blocked automated PDF download for Solchenbach).
  - No LiPF6 producer, production volume or price was found on an opened page; the USGS fluorspar summary covers the feedstock only.
  - A source that states the LiF plus PF5 synthesis route was not opened. Wikipedia gives the route as phosphorus pentachloride with lithium fluoride and hydrogen fluoride; Yang et al. give the reverse decomposition (LiPF6 to LiF and PF5).
sources:
  pubchem-lipf6:
    title: 'PubChem compound record: Lithium hexafluorophosphate (CID 23688915)'
    id: CID 23688915; CAS 21324-40-3; EC 244-334-7
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23688915
    year: 2026
    kind: database
    license: public domain (NCBI)
  sa-sds:
    title: 'Safety Data Sheet: Lithium Hexafluorophosphate (Stanford Advanced Materials)'
    id: revised 17 November 2022, accessed 25 August 2023 per the sheet
    url: https://samaterials.com/tds/1697120063-2019-lithium-hexafluorophosphate-powder-sds.pdf
    year: 2022
    kind: datasheet
    license: manufacturer document, linked not reproduced
  sony-sds:
    title: Product Safety Data Sheet, Sony Energy Devices US18650VT lithium-ion rechargeable battery
    id: Sony Energy Devices Corp. Koriyama Plant, prepared 23 March 2007
    url: https://support.blackanddecker.com/hc/en-us/article_attachments/360012464837
    year: 2007
    kind: datasheet
    license: manufacturer document, linked not reproduced
  yang2006:
    title: Thermal Stability of LiPF6 Salt and Li-ion Battery Electrolytes Containing LiPF6
    id: Yang, Zhuang and Ross, Lawrence Berkeley National Laboratory; OSTI 898281; J. Power Sources 161, 573 (2006)
    url: https://www.osti.gov/biblio/898281
    year: 2006
    kind: paper
    license: US Department of Energy national laboratory report (OSTI)
  solchenbach2018:
    title: Quantification of PF5 and POF3 from Side Reactions of LiPF6 in Li-Ion Batteries
    id: doi:10.1149/2.0481813jes (J. Electrochem. Soc. 165, A3022)
    url: https://iopscience.iop.org/article/10.1149/2.0481813jes
    year: 2018
    kind: paper
    license: CC BY 4.0
  landesfeind2019:
    title: Temperature and Concentration Dependence of the Ionic Transport Properties of Lithium-Ion Battery Electrolytes
    id: doi:10.1149/2.0571912jes (J. Electrochem. Soc. 166, A3079)
    url: https://iopscience.iop.org/article/10.1149/2.0571912jes
    year: 2019
    kind: paper
    license: CC BY-NC-ND 4.0
  zhao2020:
    title: Designing electrolytes with polymerlike glass-forming properties and fast ion transport at low temperatures
    id: doi:10.1073/pnas.2004576117 (PNAS 117, 26053)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC7585027/
    year: 2020
    kind: paper
    license: PNAS license (page states 'Published under the PNAS license')
  larsson2017:
    title: Toxic fluoride gas emissions from lithium-ion battery fires
    id: doi:10.1038/s41598-017-09784-z (Scientific Reports 7, 10018)
    url: https://www.nature.com/articles/s41598-017-09784-z
    year: 2017
    kind: paper
    license: open access (Creative Commons; exact licence not checked)
  nasa-techbrief-2005:
    title: Ester-Based Electrolytes for Low-Temperature Li-Ion Cells (NASA Tech Briefs, December 2005, NPO-41097)
    id: NASA Tech Briefs December 2005, page 25; NTRS 20110016439
    url: https://ntrs.nasa.gov/citations/20110016439
    year: 2005
    kind: report
    license: public domain (NASA)
  usgs-fluorspar-2026:
    title: Mineral Commodity Summaries 2026, Fluorspar
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    year: 2026
    kind: report
  nist-atomic-weights:
    title: NIST Atomic Weights and Isotopic Compositions, lithium, phosphorus and fluorine pages
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Li&ascii=html&isotype=some
    kind: database
  wiki-lipf6:
    title: Lithium hexafluorophosphate (Wikipedia, production and chemistry)
    url: https://en.wikipedia.org/wiki/Lithium_hexafluorophosphate
    kind: web
license: CC-BY-4.0
updated: '2026-10-17'
review:
  status: draft
  method: assistant
  checked_values: 18
  unreachable: 0
  caveats: 6
  note: Written by an AI assistant on 2026-10-17. Values from Yang et al., Landesfeind and Gasteiger, Larsson et al., the Stanford Advanced Materials sheet, the Sony sheet and the NASA Tech Brief were read in text extracted from the source PDFs; PubChem values were read from its JSON record. The Solchenbach et al. values and the Zhao et al. bound were read through a web summary of the open article. 6 values carry caveats noted in the file. No values were taken from memory.
story:
  risk_groups:
    - title: For people
      level: 3
      verdict: Corrosive; toxic; makes HF
      lead: The pure salt is a corrosive, toxic powder, and it gives off hydrogen fluoride when it meets water or heat.
      points:
        - label: The powder
          line: 'A supplier safety data sheet (revised 17 November 2022) gives signal word Danger: toxic in contact with skin (H311), causes severe skin burns and eye damage (H314), serious eye damage (H318) and harmful if swallowed (H302). PubChem''s aggregated ECHA data also lists H372 (organ damage from repeated exposure) at 81.8% of notifications, which the supplier sheet does not.'
        - label: Moisture
          line: The salt is moisture sensitive. With water it gives off hydrogen fluoride (HF) and phosphoryl fluoride (POF3). The sheet lists hydrogen fluoride as a hazardous decomposition product.
        - label: In a fire
          line: Fire tests of seven commercial cell types, all with LiPF6 electrolytes, measured 20 to 200 mg of HF per Wh of nominal capacity, and 15 to 22 mg/Wh of POF3 in some tests. The authors name a spacecraft among confined places where this could be a serious threat.
    - title: If it fails
      lead: These results come from laboratory heating and fire tests, not from spacecraft failures.
      points:
        - label: Heating the salt
          line: Dry LiPF6 was stable up to 380 K, then split into solid LiF and PF5 gas. With 300 ppm of water vapour the onset dropped by about 27 K and HF and POF3 formed first.
        - label: Acid in the cell
          line: In ethylene carbonate with 1.5 M LiPF6, water alone gave no detectable POF3 up to 40 °C, but 5000 ppm of methanesulfonic acid gave about 1000 ppm at 25 °C. The authors conclude acidic species, not water alone, drive the breakdown.
        - label: Cold
          line: A commercial 1 M LiPF6 electrolyte in EC and DMC conducted generally less than 0.1 mS/cm below -20 °C.
    - title: Handling and storage
      points:
        - label: Storage
          line: Handle and store under dry inert gas, tightly sealed, refrigerated, away from water, heat, acids and oxidising agents.
        - label: Protection
          line: Use a chemical fume hood and impervious gloves (nitrile rubber 0.11 mm, stated breakthrough 480 minutes). Wash skin and rinse eyes with water if exposed.
        - label: Spills
          line: Use a neutralising agent and keep the material out of drains.
  why: 'Lithium hexafluorophosphate (LiPF6) is a salt: a solid made of lithium ions (Li+) and hexafluorophosphate ions (PF6-), a phosphorus atom surrounded by six fluorine atoms. A lithium-ion cell needs a liquid that lets lithium ions travel between its two electrodes, and the usual recipe is this salt dissolved in organic carbonate solvents such as ethylene carbonate (EC) and dimethyl carbonate (DMC). A Lawrence Berkeley paper calls it the most widely used salt in commercial Li-ion cells. It is chosen because the solution conducts well: a 1.0 M solution (one mole of salt per litre) in EC and DMC conducts 10.8 to 12.9 mS/cm at 20 to 30 °C. The weak point is the salt itself. It is chemically fragile, splitting into lithium fluoride (LiF) and phosphorus pentafluoride (PF5) when heated, and making hydrogen fluoride (HF) and POF3 when water or acid is present. That is why cells are kept dry, and why cells that burn can release toxic fluoride gases.'
  uses:
    - where: Commercial lithium-ion cells
      line: LiPF6 is the most widely used salt in the electrolytes of commercial Li-ion cells, according to Yang and colleagues. All seven commercial cell types in a Swedish fire study had LiPF6 electrolytes.
    - where: NASA low-temperature cells
      line: NASA's Jet Propulsion Laboratory tested 1.0 M LiPF6 in five carbonate and ester solvent mixtures in cells with carbon anodes and LiNi0.8Co0.2O2 cathodes, reporting improved performance at temperatures as low as -70 °C. These were laboratory cells, not flight batteries.
  can_do:
    - label: Conducting lithium ions
      value: 10.8 to 12.9 mS/cm
      benchmark: ionic_conductivity
      line: A 1.0 M solution of LiPF6 in EC and DMC (1:1 by weight) measured 10.8 to 12.9 mS/cm between 20 and 30 °C by impedance spectroscopy, and about 17 mS/cm at +50 °C. Conductivity peaks near 0.75 M at -10 °C and 1 M at +50 °C, and falls to about 0.5 mS/cm at 3.0 M and -10 °C.
    - label: Staying stable when dry
      value: Stable to 380 K
      benchmark: salt_stability_limit_dry
      line: Neat LiPF6 in dry gas showed no mass change in an hour at 343 K or 363 K, then 3.2% mass loss after another hour at 383 K. The other thermogravimetry study found a decomposition onset of 165 °C after a hold at 120 °C, so the onset depends on the method.
    - label: Low temperature
      value: Under 0.1 mS/cm below -20 °C
      benchmark: conductivity_cold_upper_bound
      line: A commercial 1 M LiPF6 EC/DMC electrolyte conducted generally less than 0.1 mS/cm below -20 °C. The NASA brief reports better performance in cells with ester-containing mixtures at temperatures as low as -70 °C, with no numbers given.
  compare: Dry LiPF6 begins to break down at 380 K (about 107 °C) in one study and 165 °C in another, while with water vapour the onset falls by about 27 K in the first and to about 90 °C in the second. The supplier datasheet lists a melting point of 200 °C with decomposition, so none of these studies supports treating 200 °C as a safe limit. No source in this record compares LiPF6 with other lithium salts such as LiBF4 or LiFSI, so no such comparison is made.
  handling:
    - Keep it dry and sealed, under dry inert gas, refrigerated, away from heat, acids and oxidising agents.
    - It is corrosive and toxic; use a fume hood and impervious gloves.
    - Water and acid give hydrogen fluoride, so keep moisture out of cells and the glovebox.
    - Fire releases HF; firefighters need a self-contained respirator and a fully protective suit.
  good_for:
    - Ion transport. A 1.0 M solution in EC and DMC conducts 10.8 to 12.9 mS/cm at 20 to 30 °C.
    - Wide use. It is the most widely used salt in commercial Li-ion cell electrolytes, per a Berkeley Lab paper.
  watch_out:
    - Heat. Dry salt splits into LiF and PF5 above about 380 K in one study, and earlier if water is present.
    - Moisture and acid. They give HF and POF3, and 300 ppm of water vapour lowered the onset by about 27 K.
    - Fire. Burning commercial cells released 20 to 200 mg of HF per Wh.
    - Cold. Conductivity of a commercial 1 M EC/DMC electrolyte fell below 0.1 mS/cm under -20 °C.
  verdict: 'LiPF6 is the dependable, highly conductive default salt for carbonate electrolytes, but it is chemically fragile: heat, water and acid turn it into HF and POF3, and its solutions lose most conductivity below -20 °C. All numbers here are ground laboratory results; no flight data for the salt itself was found.'
  compare_rows:
    - label: Density
      benchmark: density
      scope: material
    - label: Melting point
      benchmark: melting_point
      scope: material
    - label: Molar mass
      benchmark: molar_mass
      scope: material
  recipe:
    line: Lithium hexafluorophosphate is one lithium ion (Li+) and one hexafluorophosphate ion (PF6-), which is a phosphorus atom surrounded by six fluorine atoms. Atomic weights are NIST standard values. Wikipedia describes manufacture by reacting phosphorus pentachloride with lithium fluoride and hydrogen fluoride, which gives LiPF6 and hydrogen chloride. Heating or wetting the salt reverses the chemistry toward lithium fluoride and phosphorus pentafluoride, which is why it is kept dry.
    parts:
      - name: Lithium
        symbol: Li
        atoms: 1
        atomic_weight: 6.938
        role: The charge carrier that moves between the electrodes. NIST gives lithium as an interval; the lower bound is entered.
      - name: Phosphorus
        symbol: P
        atoms: 1
        atomic_weight: 30.974
        role: Sits at the centre of the anion, bonded to six fluorines.
      - name: Fluorine
        symbol: F
        atoms: 6
        atomic_weight: 18.998
        role: Six fluorines surround the phosphorus. They are the source of hydrogen fluoride when the salt meets water.
supply:
  - subject: Fluorspar (calcium fluoride), feedstock for hydrogen fluoride, which is the starting point for LiPF6
    abundance: World reserves 330,000 thousand t (2025 table); world mine production 10,000 thousand t in 2025. The US was 100% net import reliant on fluorspar
    producers:
      - country: China
        share_percent: 60
        year: 2025
      - country: Mongolia
        share_percent: 15
        year: 2025
      - country: Mexico
        share_percent: 15
        year: 2025
    critical_lists: []
    recycling: Primary aluminum producers recycle HF and fluorides from smelting operations.
    substitutes:
      - Fluorosilicic acid recovered from phosphate rock processing has been used as an alternative to fluorspar in making aluminum fluoride and HF.
    source: usgs-fluorspar-2026
    where: World Mine Production and Reserves table (2025; shares calculated by Space Mushroom from the 10,000 thousand t world total); Salient Statistics; Domestic Production and Use; Substitutes