Aqueous electrolyte solution and aqueous lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-2019067747-A1
Application number	US-201816035787-A
Country	US
Kind code	A1
Filing date	Jul 16, 2018
Priority date	Aug 30, 2017
Publication date	Feb 28, 2019
Grant date	—

Abstract

Disclosed is an aqueous electrolyte solution that is difficult to be reduced to be decomposed, and that can improve properties of a lithium ion secondary battery when the solution is applied to the battery. The aqueous electrolyte solution for a lithium ion secondary battery includes: water; a lithium ion; a TFSI anion; and a cation that can form an ionic liquid when the cation forms a salt along with the TSFI anion in an atmospheric atmosphere, the cation being at least one selected from the group consisting of an ammonium cation, a piperidinium cation, a phosphonium cation, and an imidazolium cation.

First claim

What is claimed is:

1 . An aqueous electrolyte solution for a lithium ion secondary battery comprising:
water; a lithium ion; a TFSI anion; and a cation that can form an ionic liquid when the cation forms a salt along with the TSFI anion in an atmospheric atmosphere, the cation being at least one selected from the group consisting of an ammonium cation, a piperidinium cation, a phosphonium cation, and an imidazolium cation.

2 . The aqueous electrolyte solution according to claim 1 , wherein
no less than 1 mol of the lithium ions, and no less than 1 mol of the TFSI anions are included per kilogram of the water.

3 . The aqueous electrolyte solution according to claim 1 , wherein the cation is at least the imidazolium cation.

4 . An aqueous lithium ion secondary battery comprising:
a cathode; an anode; and the aqueous electrolyte solution according to claim 1 .

5 . The aqueous lithium ion secondary battery according to claim 4 , wherein the anode contains Li 4 Ti 5 O 12 as an anode active material.

6 . A method for producing an aqueous electrolyte solution for a lithium ion secondary battery, the method comprising:
mixing water, LiTFSI, and an ionic liquid, wherein the ionic liquid is a salt of a cation and a TFSI anion, the cation being at least one selected from the group consisting of an ammonium cation, a piperidinium cation, a phosphonium cation, and an imidazolium cation.

7 . The method according to claim 6 , wherein the content of the LiTFSI is no less than 1 mol per kilogram of the water.

8 . The method according to claim 6 , wherein the ionic liquid is a salt of the imidazolium cation and the TFSI anion.

9 . A method for producing an aqueous lithium ion secondary battery, the method comprising:
producing an aqueous electrolyte solution by the method according to of claim 6 ; producing a cathode; producing an anode; and storing the aqueous electrolyte solution, the cathode, and the anode in a battery case.

10 . The method according to claim 9 , wherein Li 4 Ti 5 O 12 is used as an anode active material in the anode.

Assignees

• Toyota Motor Co Ltd

Inventors

• Nakayama Hideki
• Suyama Hiroshi

Classifications

• H01M4/485

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• C25C3/02 Primary

  of alkali or alkaline earth metals · CPC title

• H01M4/621

  Binders · CPC title

• H01M4/5825

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M2300/0045

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