Positive electrode sheet and secondary battery including the same, battery module, battery pack, and electrical apparatus

Patent metadata

Field	Value
Publication number	US-11901561-B2
Application number	US-202218069067-A
Country	US
Kind code	B2
Filing date	Dec 20, 2022
Priority date	Dec 1, 2021
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A positive electrode sheet includes a current collector including a coating region and a non-coating region, a resistance layer disposed on the current collector and including a conductive agent, a first binder, and a first positive electrode active material, and a positive electrode active material layer including a second positive electrode active material, a conductive agent, and a second binder. A resistance of the resistance layer is greater than a resistance of the positive electrode active material layer. In a cross section of the positive electrode sheet, a projection of at least a part of the positive electrode active material layer on the current collector and a projection of the resistance layer on the current collector do not overlap. A polarization parameter P of the positive electrode sheet is in a range of 0.4-65.0 and equals ((1−S)/S)·(R1/R2).

First claim

The invention claimed is:

1. A positive electrode sheet for a secondary battery, comprising:
a current collector comprising a coating region and a non-coating region other than the coating region;
a resistance layer disposed on the current collector and comprising a conductive agent, a first binder, and a first positive electrode active material; and
a positive electrode active material layer comprising a second positive electrode active material, a conductive agent, and a second binder;
wherein:
a resistance of the resistance layer is greater than a resistance of the positive electrode active material layer;
in a cross section of the positive electrode sheet, a projection of at least a part of the positive electrode active material layer on the current collector and a projection of the resistance layer on the current collector do not overlap, and
a polarization parameter P of the positive electrode sheet is in a range of 0.4-65.0, and the polarization parameter P=((1−S)/S)·(R1/R2), wherein S is an area ratio of the resistance layer relative to the coating region of the current collector, R1 is a film resistance value of the positive electrode sheet in a part where the resistance layer is provided, and R2 is a film resistance value of the positive electrode sheet in a part of the coating region where the resistance layer is not provided.

2. The positive electrode sheet according to claim 1 , wherein P is in a range of 0.5-36.0.

3. The positive electrode sheet according to claim 1 , wherein P is in a range of 1.5-8.0.

4. The positive electrode sheet according to claim 1 , wherein S is in a range of 0.15-0.85.

5. The positive electrode sheet according to claim 1 , wherein S is in a range of 0.40-0.60.

6. The positive electrode sheet according to claim 1 , wherein a projection of a part of the positive electrode active material layer on the current collector overlaps the projection of the resistance layer on the current collector.

7. The positive electrode sheet according to claim 1 , wherein a projection of the positive electrode active material layer on the current collector and the projection of the resistance layer on the current collector do not overlap at all.

8. The positive electrode sheet according to claim 1 , wherein in the resistance layer:
a mass content of the first binder is 10.0-85.0 wt % based on a total weight of the resistance layer;
a mass content of the first positive electrode active material is 10.0-70.0 wt % based on the total weight of the resistance layer; and/or
a mass content of the conductive agent is 5.0-20.0 wt % based on the total weight of the resistance layer.

9. The positive electrode sheet according to claim 1 , wherein R1/R2 is in a range of 1.15-26.00.

10. The positive electrode sheet according to claim 9 , wherein:
R1 is in a range of 0.3-8.0Ω; and/or
R2 is in a range of 0.3-4.0Ω.

11. The positive electrode sheet according to claim 1 , wherein: the first positive electrode active material and the second positive electrode active material each comprise one or more selected from lithium cobalt oxide, lithium manganate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminium oxide, lithium iron phosphate, or lithium manganese nickel oxide; the conductive agent comprises one or more selected from graphite, carbon black, acetylene black, graphene or carbon nanotubes; and the first binder and the second binder each comprise one or more selected from polyvinylidene fluoride, polyacrylic acid, polytetrafluoroethylene, or polyimide.

12. The positive electrode sheet according to claim 1 , wherein: the first positive electrode active material and the second positive electrode active material each comprise one or more selected from layered transition metal oxide, polyanionic compound, Prussian blue compound, sulfide, nitride, carbide, or titanate; the conductive agent comprises one or more selected from graphite, carbon black, acetylene black, graphene, or carbon nanotubes; and the first binder and the second binder each comprise one or more selected from polyvinylidene fluoride, polyacrylic acid, polytetrafluoroethylene or polyimide.

13. The positive electrode sheet according to claim 1 , wherein a compaction density of the positive electrode sheet is 2.0-4.0 g/cm 3 .

14. The positive electrode sheet according to claim 1 , wherein a compaction density of the positive electrode sheet is 2.3-4.0 g/cm 3 .

15. The positive electrode sheet according to claim 1 , wherein:
a thickness of the current collector is 8-14 μm;
a thickness of the positive electrode sheet is 100-200 μm; and/or
a thickness of the resistance layer is 1-30 μm.

16. The positive electrode sheet according to claim 1 , wherein D v 50 of at least one of the first positive electrode active material or the second positive electrode active material is 1-20 μm.

17. A secondary battery, comprising:
a positive electrode comprising a positive electrode sheet, the positive electrode sheet comprising:
a current collector comprising a coating region and a non-coating region other than the coating region;
a resistance layer disposed on the current collector and comprising a conductive agent, a first binder, and a first positive electrode active material; and
a positive electrode active material layer comprising a second positive electrode active material, a conductive agent, and a second binder;
wherein:
a resistance of the resistance layer is greater than a resistance of the positive electrode active material layer;
in a cross section of the positive electrode sheet, a projection of at least a part of the positive electrode active material layer on the current collector and a projection of the resistance layer on the current collector do not overlap, and
a polarization parameter P of the positive electrode sheet is in a range of 0.4-65.0, and the polarization parameter P=((1−S)/S)·(R1/R2), wherein S is an area ratio of the resistance layer relative to the coating region of the current collector, R1 is a film resistance value of the positive electrode sheet in a part where the resistance layer is provided, and R2 is a film resistance value of the positive electrode sheet in a part of the coating region where the resistance layer is not provided.

18. An electrical apparatus, comprising at least one of the secondary battery according to claim 17 .

19. A battery module, comprising:
a secondary battery comprising a positive electrode, the positive electrode comprising a positive electrode sheet, and the positive electrode sheet comprising:
a current collector comprising a coating region and a non-coating region other than the coating region;
a resistance layer disposed on the current collector and comprising a conductive agent, a first binder, and a first positive electrode active material; and
a positive electrode active material layer comprising a second positive electrode active material, a conductive agent, and a second binder;
wherein:
a resistance of the resistance layer is greater than a resistance of the positive electrode active material layer;
in a cross section of the positive electrode sheet, a projection of at least a part of the positive electrode active material layer on the current collector and a projection of the resistance layer on the current collector do not overlap, and
a polarization parameter P of the positive electrode sheet is in a range of 0.4-65.0, and the polarization parameter P=((1−S)/S)·(R1/R2), wherein S is an area ratio of the resistance layer relative to the coating region of the

Assignees

• Contemporary Amperex Technology Co Ltd

Inventors

• Li Quanguo
• Ye Yonghuang
• Shi Songjun
• Liu Qian
• Peng Jun
• Huang Fajun

Classifications

• H01M4/628 Primary

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

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M4/623

  fluorinated polymers · CPC title

• H01M4/625

  Carbon or graphite · CPC title