Aqueous electrolytes with bis(fluorosulfonyl)imide salt electrolyte and ionic liquid system and batteries using the electrolyte system

Patent metadata

Field	Value
Publication number	US-10868339-B2
Application number	US-201715831781-A
Country	US
Kind code	B2
Filing date	Dec 5, 2017
Priority date	Dec 5, 2017
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

An aqueous electrolyte composition suitable for a lithium secondary battery is provided. The aqueous electrolyte composition contains water; lithium bis(fluorosulfonyl) imide (LiFSI); and an ionic liquid comprising an organic cation and a bis(fluorosulfonyl) imide anion (FSI); wherein the ionic liquid is a liquid at 20° C. A lithium secondary battery containing the aqueous electrolyte and a vehicle at least partially powered by the battery are also provided.

First claim

The invention claimed is:

1. An aqueous electrolyte for a lithium-ion secondary battery comprising:
water;
lithium bis(fluorosulfonyl) imide (LiFSI); and
an ionic liquid comprising an organic cation and a bis(fluorosulfonyl) imide anion (FSI);
wherein
the organic cation of the ionic liquid is selected from the group consisting of an alkyl-ammonium cation, an alkylpiperidinium cation, an alkylpyrrolidinium cation, an alkylimidazolium cation and an alkylphosphonium cation,
a content of the LiFSI is from 3 M to 20 M,
a mole ratio of the LiFSI, water and the ionic liquid is such that for 1 mole of the LiFSI, there are 0.1 to 20 mole of the ionic liquid and 0.1 to 10 mole water, and the ionic liquid is a liquid at 20° C.

2. The aqueous electrolyte for a lithium secondary battery according to claim 1 , wherein the organic cation is selected from the group consisting of formulae (I), (II), (III), (IV) and (V) and mixtures thereof:

wherein R 1 to R 4 are each independently H or a linear, branched, cyclic or alicyclic hydrocarbon group having 1 to 18 carbon atoms, optionally substituted with an ether oxygen, with the proviso that at least one of R 1 to R 4 cannot be H.

3. The aqueous electrolyte for a lithium secondary battery according to claim 1 , wherein a concentration of the LiFSI is from 4 M to 20 M.

4. The aqueous electrolyte for a lithium secondary battery according to claim 1 , further comprising a lithium salt of an anion comprising a fluoroalkylsulfonyl group of formula (I):
R—SO2—  (I)

wherein R is a perfluoroalkyl group of 1-5 carbons;
wherein a molar ratio of the lithium fluoroalkylsulfonyl group anion salt to total moles of LiFSI and the lithium fluoroalkylsulfonyl group anion salt is less than ½.

5. The aqueous electrolyte for a lithium secondary battery according to claim 4 , wherein a total concentration of the LiFSI and the lithium fluoroalkylsulfonyl group anion salt is from 3 M to 20 M.

6. A lithium secondary battery comprising:
an anode capable of intercalation and de-intercalation of lithium ions;
a cathode capable of intercalation and de-intercalation lithium ions; and
an aqueous electrolyte according to claim 1 in contact with the anode and cathode.

7. The lithium secondary battery according to claim 6 , wherein the cation is selected from the group consisting of formulae (I), (II), (III), (IV) and (V) and mixtures thereof:

wherein R 1 to R 4 are each independently H or a linear, branched, cyclic or alicyclic hydrocarbon group having 1 to 18 carbon atoms, optionally substituted with an ether oxygen, with the proviso that at least one of R 1 to R 4 cannot be H.

8. The lithium secondary battery according to claim 6 , wherein a concentration of the LiFSI is from 4 M to 20 M.

9. The lithium secondary battery according to claim 6 , further comprising a lithium salt of an anion comprising a fluoroalkylsulfonyl group of formula (I):
R—SO 2 —  (I)

wherein R is a perfluoroalkyl group of 1-5 carbons;
wherein a molar ratio of the lithium fluoroalkylsulfonyl group anion salt to total moles of LiFSI and the lithium fluoroalkylsulfonyl group anion salt is less than ½.

10. The lithium secondary battery according to claim 9 , wherein a total concentration of the LiFSI and the lithium fluoroalkylsulfonyl group anion salt is from 3 M to 20 M.

11. The lithium secondary battery of claim 6 , wherein the cathode capable of intercalation and de-intercalation lithium ions comprises at least one compound selected from the group consisting of LiMn 2 O 4 , LiCoO 2 , LiFe 2 (PO 4 ), LiMn 1/3 Ni 1/3 Co 1/3 O 2 , LiNi 0.5 Mn 1.5 O 4 and LiCoPO 4 .

12. The lithium secondary battery of claim 6 , wherein the anode capable of intercalation and de-intercalation of lithium ions is stable to water and has a redox potential greater than 0.5 V vs Li/Li+.

13. The lithium secondary battery of claim 6 , wherein the anode capable of intercalation and de-intercalation of lithium ions comprises at least one compound selected from the group consisting of Li 4 Ti 5 O 12 , elemental Sulfur, Mo 6 S 8 , Cu 2 V 2 O 7 , TiS 4 , NbS 5 and Li terephthalate.

14. A vehicle, comprising the lithium secondary battery of claim 6 .

Assignees

• Toyota Eng & Mfg North America

Inventors

• Takechi Kensuke
• Yang Ruidong

Classifications

• C07F9/5407

  Acyclic saturated phosphonium compounds · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M4/5815

  Sulfides · CPC title

• H01M4/131

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title