Positive electrode plate, secondary battery, battery module, battery pack, and electrical device

Patent metadata

Field	Value
Publication number	US-12062783-B2
Application number	US-202318331246-A
Country	US
Kind code	B2
Filing date	Jun 8, 2023
Priority date	Jan 14, 2022
Publication date	Aug 13, 2024
Grant date	Aug 13, 2024

Abstract

A positive electrode plate, a secondary battery, a battery module, a battery pack, and an electrical device are disclosed. The positive electrode plate includes a positive current collector, and a positive active material layer disposed on at least one surface of the positive current collector. The positive active material layer includes a first active material layer and a second active material layer that are sequentially stacked in a direction away from the surface. The first active material layer includes a first composite particle. The first composite particle includes a first lithium iron phosphate particle and a first carbon layer that coats a surface of the first lithium iron phosphate particle. The second active material layer includes a second composite particle. The second composite particle includes a second lithium iron phosphate particle and a second carbon layer that coats a surface of the second lithium iron phosphate particle.

First claim

What is claimed is:

1. A positive electrode plate, comprising:
a positive current collector; and
a positive active material layer disposed on at least one surface of the positive current collector,
wherein the positive active material layer comprises a first active material layer and a second active material layer that are sequentially stacked in a direction away from the surface, the first active material layer comprises a first composite particle, the first composite particle comprises a first lithium iron phosphate particle and a first carbon layer that coats a surface of the first lithium iron phosphate particle, the second active material layer comprises a second composite particle, the second composite particle comprises a second lithium iron phosphate particle and a second carbon layer that coats a surface of the second lithium iron phosphate particle, and
wherein a graphitization degree of the first composite particle is 0.3 to 0.5, and a graphitization degree of the second composite particle is 0.1 to 0.2.

2. The positive electrode plate according to claim 1 , wherein
the first composite particle comprises a primary particle,
the second composite particle comprises a secondary particle formed by aggregating a plurality of primary particles, and an average particle diameter Ds of the first composite particle is less than an average particle diameter D 50 of the second composite particle.

3. The positive electrode plate according to claim 2 , wherein
the average particle diameter D 50 of the first composite particle is 1 μm to 4 μm; and/or
the average particle diameter D 50 of the second composite particle is 6 μm to 12 μm.

4. The positive electrode plate according to claim 2 , wherein the secondary particle is of a spherical or quasi-spherical morphology.

5. The positive electrode plate according to claim 1 , wherein
a specific surface area of the first composite particle is 10 m 2 /g to 15 m 2 /g; and/or
a specific surface area of the second composite particle is 5 m 2 /g to 10 m 2 /g.

6. The positive electrode plate according to claim 1 , wherein
a ratio of a coating weight CW1 of the first active material layer to a coating weight CW2 of the second active material layer is 0.8 to 1.2.

7. The positive electrode plate according to claim 6 , wherein
the coating weight CW1 of the first active material layer satisfies 0.115 mg/cm 2 ≤ CW1≤ 0.195 mg/cm 2 ; and/or
the coating weight CW2 of the second active material layer satisfies 0.115 mg/cm 2 ≤ CW2≤ 0.195 mg/cm 2 .

8. The positive electrode plate according to claim 1 , wherein
the first active material layer comprises a first conductive agent, and, on a basis that a total weight of the first active material layer is 100%, a mass percent of the first conductive agent is A; and
the second active material layer comprises a second conductive agent, and, on a basis that a total weight of the second active material layer is 100%, a mass percent of the second conductive agent is B, wherein
A<B, and 1 wt %≤B−A≤3 wt %.

9. The positive electrode plate according to claim 1 , wherein
a powder compaction density of the first active material layer under a pressure of 600 MPa is 2.4 g/cc to 2.65 g/cc; and/or
a powder compaction density of the second active material layer under a pressure of 600 MPa is 2.2 g/cc to 2.45 g/cc.

10. A secondary battery, comprising a positive electrode plate, a separator, and a negative electrode plate, wherein the positive electrode plate is the positive electrode plate according to claim 1 .

11. A battery module, comprising the secondary battery according to claim 10 .

12. A battery pack, comprising the battery module according to claim 11 .

13. An electrical device, comprising the battery pack according to claim 12 .

Assignees

• Contemporary Amperex Technology Co Ltd

Inventors

• Pu Jingjing
• Wu Yanying
• Wang Xinghui

Classifications

• H01M10/0525

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

• H01M4/136 Primary

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/5825

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

• H01M4/366 Primary

  as layered products · CPC title