Stable electrolyte based on a fluorinated ionic liquid and its use in high current rate lithium-air batteries

Patent metadata

Field	Value
Publication number	US-12166177-B2
Application number	US-201917437534-A
Country	US
Kind code	B2
Filing date	Mar 11, 2019
Priority date	Mar 11, 2019
Publication date	Dec 10, 2024
Grant date	Dec 10, 2024

Abstract

An electrolyte composition, for use in particular in a lithium-air battery, includes
(A) a fluorinated cation of structure R 1 R 2 R 3 N + -(linker 1 )-O-(linker 2 )-(FC), wherein R 1 , R 2 and R 3 are C1-C6 linear or branched alkyl groups, linkers linker 1 and linker 2 contain alkylene or oxyalkylene chains and FC is a fluorinated alkyl group; (B) an anion; (C) a solvent containing at least one —O—CH 2 —CH 2 —O— or —O—CH 2 —CHMe-O— group, an ϵ-caprolactone oligomer, or a dialkyl sulfoxide; and (D) a lithium salt.

First claim

The invention claimed is:

1. An electrolyte composition comprising:
(A) a cation having the following structural formula (1):
R 1 R 2 R 3 N + -(linker 1 )-O-(linker 2 )-(FC)  (1)

wherein:
R 1 and R 2 are both C1-C6 linear or branched alkyl groups;
R 3 is a C1-C6 linear or branched alkyl group;
the linker 1 consists of: an alkylene chain —(CH 2 ) n — wherein n≥1, or a chain of formula —(CH 2 —O—CH 2 —) p wherein p≥1;
the linker 2 consists of an alkylene chain —(CH 2 ) m — wherein m≥1, or a chain of formula —(CH 2 —O—CH 2 —) q wherein q≥1;
the group FC is a fluorinated alkyl group of formula C a H b F c wherein b+c=2a+1, where c is at least 1 and at most 2a+1 and where a is at least 1 and at most 10;
(B) an anion, wherein the anion (B) is selected from the group consisting of:
dicyanamide; halides; and bis(pentafluoroethyl)trifluorophosphate;
(C) at least 8% and at most 50% by weight, with respect to 100% by weight constituted by all the components of the electrolyte composition, of a solvent, wherein the solvent is one containing at least one —O—CH 2 —CH 2 —O— or —O—CH 2 —CHMe-O— group, an ϵ-caprolactone oligomer, or a dialkyl sulfoxide; and
(D) a lithium salt in an amount of at least 0.1 mol·kg −1 and at most 0.9 mol·kg −1 with respect to the electrolyte composition as a whole.

2. The electrolyte composition according to claim 1 , wherein the solvent containing at least one —O—CH 2 —CH 2 —O— or —O—CH 2 —CHMe-O— group shows end-capping —O-Me groups.

3. The electrolyte composition according to claim 1 , wherein the solvent containing at least one —O—CH 2 —CH 2 —O— or —O—CH 2 —CHMe-O— group has a molecular weight Mw of not more than 225 g·mol −1 .

4. The electrolyte composition according to claim 1 , wherein the solvent containing at least one —O—CH 2 —CH 2 —O— or —O—CH 2 —CHMe-O— group is selected from the group consisting of: dimethoxyethane (DME), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme, TEGDME), and tetraethylene glycol dimethyl ether (tetraglyme).

5. The electrolyte composition according to claim 1 , wherein the solvent containing at least one —O—CH 2 —CH 2 —O— or —O—CH 2 —CHMe-O— group is dimethoxyethane (DME).

6. The electrolyte composition according to claim 1 , wherein with respect to 100% by weight constituted by all the components of the electrolyte composition, the amount of solvent (C) is at least 13% and at most 40%.

7. The electrolyte composition according to claim 1 , wherein the lithium salt (D) is selected from the group consisting of: LiTFSI, LiPF 6 , LiBF 4 , LiCIO 4 , LiFSI, LiBOB LiAsF 6 , LiFAP, LiTriflate, LiDMSI, LiHPSI, LiBETI, LiDFOB, LiBFMB, LiBison, LiDCTA, LiTDI, LIPDI.

8. The electrolyte composition according to claim 1 , wherein the lithium salt (D) is LiTFSI.

9. The electrolyte composition according to claim 1 , wherein the lithium salt (D) is present in an amount of at least 0.25 mol·kg −1 and at most 0.50 mol·kg −1 with respect to the electrolyte composition as a whole.

10. The electrolyte composition according to claim 1 , wherein in linker 1 :
n is at most 10;
p is at most 5;
and in linker 2 :
m is at most 10; and
q is at most 5.

11. The electrolyte composition according to claim 1 , wherein the linker group linker 1 is ethylene —CH 2 —CH 2 —.

12. The electrolyte composition according to claim 1 , wherein the linker group linker 2 is methylene —CH 2 —.

13. The electrolyte composition according to claim 1 , wherein c>b in the fluorinated alkyl group FC.

14. The electrolyte composition according to claim 1 , wherein the linker group linker 1 is ethylene —CH 2 —CH 2 —, the linker group linker 2 is methylene —CH 2 —, R 1 and R 2 are ethyl and R 3 is methyl, and FC is CF 3 .

15. The electrolyte composition according to claim 1 , wherein anion (B) is: C n F 2n+1 —SO 2 —N—SO 2 —C m F 2m+1 − , C n F 2n+1 COO − and/or C n F 2n+1 SO 3 − , wherein n and m are at least 1 and at most 10; PF 6 − , BF 4 − .

16. The electrolyte composition according to claim 1 , wherein anion (B) is F 3 C—SO 2 —(N − )—SO 2 —CF 3 .

17. The electrolyte composition according to claim 1 , wherein cation (A) and anion (B) are together N,N-diethyl-N-methyl-N-((trifluoroethoxy)ethyl)ammonium bis(trifluoromethanesulfonyl)imide:

18. A lithium-air battery comprising:
a negative electrode containing a negative-electrode active material;
a positive electrode using oxygen as a positive-electrode active material; and
an electrolyte medium arranged between the negative electrode and the positive electrode;
wherein the electrolyte medium comprises the electrolyte composition according to claim 1 .

Assignees

• Toyota Motor Europe
• Toyota Motor Co Ltd

Inventors

• Castro Laurent
• Bardé Fanny

Classifications

• H01M2300/0037

  Mixture of solvents · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2300/0045

  Room temperature molten salts comprising at least one organic ion · CPC title