Lithium ion secondary battery and method of manufacturing same

Patent metadata

Field	Value
Publication number	US-11056713-B2
Application number	US-201815934408-A
Country	US
Kind code	B2
Filing date	Mar 23, 2018
Priority date	Apr 3, 2017
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A lithium ion secondary battery at least includes a positive electrode, a negative electrode, and an electrolyte solution. The positive electrode at least includes a positive electrode active material and a binder. The positive electrode active material includes more than or equal to 0.08 mass % of a lithium carbonate and a remainder of a lithium complex oxide. The binder is at least one selected from a group consisting of polytetrafluoroethylene, polyethylene oxide, and carboxymethylcellulose. The electrolyte solution at least includes a solvent and a lithium salt. The solvent is at least one of N,N-dimethylformamide and dimethylacetamide. A concentration of the lithium salt in the electrolyte solution is more than or equal to 1.9 mol/l and less than or equal to 2.3 mol/l.

First claim

What is claimed is:

1. A lithium ion secondary battery at least comprising a positive electrode, a negative electrode, and an electrolyte solution,
the positive electrode at least including a positive electrode active material and a binder,
the positive electrode active material including from 0.10 mass % to 0.2 mass % of a lithium carbonate and a remainder of a lithium complex oxide,
the binder being at least one selected from a group consisting of polytetrafluoroethylene, polyethylene oxide, and carboxymethylcellulose,
the electrolyte solution at least including a solvent and a lithium salt,
the solvent being at least one of N,N-dimethylformamide and dimethylacetamide,
a concentration of the lithium salt in the electrolyte solution being more than or equal to 1.9 mol/l and less than or equal to 2.3 mol/l.

2. The lithium ion secondary battery according to claim 1 , wherein the lithium complex oxide has a lamellar rock salt type structure.

3. The lithium ion secondary battery according to claim 1 , wherein the electrolyte solution has an electric conductivity of more than or equal to 9.73 mS/cm and less than or equal to 19.84 mS/cm.

4. The lithium ion secondary battery according to claim 1 , wherein the lithium complex oxide has the following formula (I):
LiNi x Co y Me z O 2   (I)

where Me is Mn or Al, and
x, y, and z satisfy 0<x<1, 0<y<1, 0<z<1, and x+y+z=1.

5. The lithium ion secondary battery according to claim 4 , wherein x, y, and z satisfy 0.2≤x≤0.4, 0.2≤y≤0.4, 0.2≤z≤0.4.

6. The lithium ion secondary battery according to claim 4 , wherein x, y, and z satisfy 0.5≤x≤0.9, 0.09≤y≤0.3, 0.01≤z≤0.2.

7. The lithium ion secondary battery according to claim 1 , wherein the positive electrode active material includes from 0.14 mass % to 0.2 mass % of the lithium carbonate and a remainder of the lithium complex oxide.

8. The lithium ion secondary battery according to claim 1 , wherein the lithium complex oxide is in the form of secondary particles having an average particle size of 1 to 30 μm.

9. The lithium ion secondary battery according to claim 1 , wherein the lithium complex oxide is at least one of LiFePO 4 and a ternary lithium complex oxide.

10. The lithium ion secondary battery according to claim 1 , wherein the electrolyte solution has an electric conductivity of more than or equal to 15.93 mS/cm and less than or equal to 19.84 mS/cm.

11. The lithium ion secondary battery according to claim 1 , wherein the binder is at least polytetrafluoroethylene.

12. The lithium ion secondary battery according to claim 1 , wherein the binder is at least polyethylene oxide.

13. The lithium ion secondary battery according to claim 1 , wherein the binder is at least carboxymethylcellulose.

14. The lithium ion secondary battery according to claim 1 , wherein the solvent is at least N,N-dimethylformamide.

15. The lithium ion secondary battery according to claim 1 , wherein the solvent is at least dimethylacetamide.

16. A method of manufacturing a lithium ion secondary battery, the method comprising:
preparing a positive electrode active material by exposing a lithium complex oxide to carbon dioxide;
preparing a positive electrode paste by at least mixing the positive electrode active material, a binder, and water;
manufacturing a positive electrode by drying the positive electrode paste;
manufacturing a negative electrode;
preparing an electrolyte solution at least including a solvent and a lithium salt; and
manufacturing a lithium ion secondary battery at least including the positive electrode, the negative electrode, and the electrolyte solution,
the positive electrode active material being prepared to include from 0.10 mass % to 0.2 mass % of a lithium carbonate and a remainder of the lithium complex oxide,
the binder being at least one selected from a group consisting of polytetrafluoroethylene, polyethylene oxide, and carboxymethylcellulose,
the electrolyte solution being prepared such that the solvent is at least one of N,N-dimethylformamide and dimethylacetamide and a concentration of the lithium salt is more than or equal to 1.9 mol/l and less than or equal to 2.3 mol/l.

Assignees

• Toyota Motor Co Ltd

Inventors

• Okuda Koji

Classifications

• H01M50/466

  U-shaped, bag-shaped or folded · CPC title

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title

• H01M10/0569

  characterised by the solvents · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title