Nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-11984618-B2
Application number	US-202217979108-A
Country	US
Kind code	B2
Filing date	Nov 2, 2022
Priority date	Apr 9, 2019
Publication date	May 14, 2024
Grant date	May 14, 2024

Abstract

A nonaqueous electrolyte secondary battery includes a positive electrode including a positive electrode collector, a positive electrode active material layer on part of the surface of the positive electrode collector, and an insulating layer on another part of the surface of the positive electrode collector; a negative electrode including a negative electrode collector; and a negative electrode active material layer on part of the surface of the negative electrode collector; a separator that insulates the positive and negative electrodes; and a nonaqueous electrolyte. A width of the negative electrode active material layer is wider than the positive electrode active material layer. The insulating layer protrudes from the negative electrode active material layer; and exhibits a thermal shrinkage factor of 13% or less in a direction parallel to the surface of a square insulating layer sample having a side length of 5 cm and heated at 150° C. for 1 hour.

First claim

What is claimed is:

1. A nonaqueous electrolyte secondary battery, comprising:
a positive electrode; a negative electrode; a separator that insulates the positive electrode and the negative electrode; and a nonaqueous electrolyte,
wherein the positive electrode includes:
a positive electrode collector;
a positive electrode active material layer containing a positive electrode active material and provided on part of a surface of the positive electrode collector; and
an insulating layer provided on another part of the surface of the positive electrode collector, so as to be adjacent to the positive electrode active material layer;

the negative electrode includes:
a negative electrode collector; and
a negative electrode active material layer containing a negative electrode active material and provided on part of a surface of the negative electrode collector;

a width of the negative electrode active material layer is wider than a width of the positive electrode active material layer,
the insulating layer contains an inorganic filler and a binder; protrudes outward in a width direction from the negative electrode active material layer; and is configured to exhibit a value of 8% or less of a thermal shrinkage factor in a direction parallel to a surface of an evaluation sample of an insulating layer formed to a square shape having a length of each side of 5 cm and heated at 150° C. for 1 hour, and
the insulating layer contains Li 3 PO 4 .

2. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the inorganic filler is at least either one of boehmite powder and alumina powder.

3. The nonaqueous electrolyte secondary battery according to claim 1 , wherein, in the insulating layer, the proportion of the binder relative to the total of the inorganic filler and the binder is lower than 30 mass %.

4. The nonaqueous electrolyte secondary battery according to claim 1 , wherein an average thickness of the insulating layer is smaller than 10 μm.

5. The nonaqueous electrolyte secondary battery according to claim 1 , wherein an average thickness of the insulating layer is 5 μm or less.

6. The nonaqueous electrolyte secondary battery according to claim 1 , wherein an average thickness of the positive electrode active material layer is 10 μm or more and 50 μm or less.

7. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the inorganic filler contains boehmite.

8. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the inorganic filler contains plate-shaped particles having an average aspect ratio of 8 or higher, and the insulating layer is configured to exhibit a value of 4% or less of a thermal shrinkage factor.

9. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the binder in the insulating layer comprises polyvinylidene fluoride.

10. The nonaqueous electrolyte secondary battery according to claim 1 , wherein a proportion of the binder contained in the insulating layer is 15 mass % or less.

11. The nonaqueous electrolyte secondary battery according to claim 1 , wherein a ratio T1/T2, where T1 denotes an average thickness of the insulating layer and T2 denotes an average thickness of the positive electrode active material layer, is 1/3 or lower.

12. The nonaqueous electrolyte secondary battery according to claim 11 , wherein the ratio T1/T2 is 1/4 or lower.

13. The nonaqueous electrolyte secondary battery according to claim 11 , wherein the ratio T1/T2 is 1/5 or lower.

14. The nonaqueous electrolyte secondary battery according to claim 1 , wherein a basis weight of the insulating layer is 0.5 mg/cm 2 or more and 1.5 mg/cm 2 or less.

15. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the inorganic filler contains plate-shaped particles having an average aspect ratio of 5 or higher.

16. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the Li 3 PO 4 in the insulating layer has a specific surface area of 0.9 to 20.3 m 2 /g and an average particle size of 1 μm or more and 10 μm or less.

17. The nonaqueous electrolyte secondary battery according to claim 1 , wherein an average particle size of the inorganic filler in the insulating layer is less than an average particle size of the Li 3 PO 4 in the insulating layer, and the average particle size of the Li 3 PO 4 in the insulating layer is less than an average particle size of the positive electrode active material.

18. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the positive electrode active material layer comprises Li 3 PO 4 .

19. The nonaqueous electrolyte secondary battery according to claim 18 , wherein the positive electrode active material layer comprises Li 3 PO 4 in an amount of 0.88 to 8.8 parts by mass relative to 100 parts by mass of the positive electrode active material.

20. The nonaqueous electrolyte secondary battery according to claim 18 , wherein the Li 3 PO 4 in the positive electrode active material layer has a specific surface area of 0.9 to 20.3 m 2 /g, an average particle size of 1 μm or more and 30 μm or less, a D 90 of 60 μm or less, a D 10 of 0.3 μm or more, and a D max of 80 μm or less.

Assignees

• Toyota Motor Co Ltd

Inventors

• Yamada Takanobu
• Kaneko Tetsuya

Classifications

• H01M50/46 Primary

  Separators, membranes or diaphragms characterised by their combination with electrodes · CPC title

• H01M4/13 Primary

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• H01M4/366

  as layered products · CPC title

• H01M4/628

  Inhibitors, e.g. gassing inhibitors, corrosion inhibitors · CPC title

• H01M10/0525

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