CN-122000572-A - Secondary battery, preparation method thereof, negative electrode plate and power utilization device

Abstract

The application provides a secondary battery and a preparation method thereof, a negative electrode plate and an electric device, wherein the secondary battery comprises a negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises a carbon material; at least part of the surface of the carbon material is coated with fiber, and the rebound rate of the negative electrode plate is 20% -40%.

Inventors

• ZHANG MENG
• Shi changchuan
• ZHANG LEI
• ZHENG YI
• SUN CHENGDONG

Assignees

• 宁德时代新能源科技股份有限公司

Dates

Publication Date

20260508

Application Date

20241101

Claims (16)

1. 1. The secondary battery is characterized by comprising a negative electrode plate, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises a carbon material; At least part of the surface of the carbon material is coated with fibers, and the rebound rate of the negative electrode plate is 20% -40%, preferably 25% -35%.
2. 2. The secondary battery according to claim 1, wherein the carbon material comprises at least one of graphite and a hard carbon material.
3. 3. The secondary battery according to claim 1 or 2, wherein the volume distribution particle diameter Dv50 of the carbon material is 10 μm to 20 μm.
4. 4. The secondary battery according to claim 1 or 2, wherein the tensile strength of the fiber is 550MPa to 2500MPa.
5. 5. The secondary battery according to claim 1 or 2, wherein the diameter of the fiber is 10nm to 1000nm.
6. 6. The secondary battery according to any one of claims 1 to 2, wherein the diameter of the fiber is 20nm to 150nm.
7. 7. The secondary battery according to any one of claims 1 to 2, wherein the length of the fiber is 200nm to 1mm.
8. 8. The secondary battery according to any one of claims 1 to 2, wherein the length of the fiber is 1 μm-100 μm.
9. 9. The secondary battery according to any one of claims 1 to 8, wherein the mass content of the fiber is 0.1wt% to 10wt% based on the mass of the anode active material.
10. 10. The secondary battery according to claim 9, wherein the mass content of the fiber is 0.5% -2%.
11. 11. The secondary battery according to any one of claims 1 to 10, wherein the fiber comprises one or more of carbon nanotubes, carbon fibers, glass fibers, metal fibers, polymer fibers, natural fibers.
12. 12. The secondary battery according to any one of claims 1 to 10, wherein the fibers include one or more of aramid fibers, lignocellulose fibers.
13. 13. A method of manufacturing a secondary battery, comprising: Fiber coating, namely drying the mixed slurry containing the anode active material and the fiber to obtain fiber coated anode active material particles, Preparing a negative electrode plate, namely coating the negative electrode slurry containing the fiber-coated negative electrode active material particles on at least one surface of a negative electrode current collector to obtain the negative electrode plate, Wherein the rebound rate of the negative electrode plate is 20% -40%; A secondary battery is prepared by assembling an electrode assembly including a negative electrode tab into a secondary battery.
14. 14. The method according to claim 13, wherein the drying process comprises any one of spray drying, freeze drying, and oven drying, optionally spray drying.
15. 15. The negative electrode plate is characterized by comprising a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises a carbon material; at least part of the surface of the carbon material is coated with fibers, and the rebound rate of the negative electrode plate is 20% -40%.
16. 16. An electric device comprising the secondary battery according to any one of claims 1 to 12 or the secondary battery obtained by the production method according to any one of claims 13 to 14 or the negative electrode sheet according to claim 15.

Description

Secondary battery, preparation method thereof, negative electrode plate and power utilization device Technical Field The application relates to the technical field of secondary batteries, in particular to a secondary battery, a preparation method thereof, a negative electrode plate and an electric device. Background In recent years, secondary batteries are widely used in energy storage power supply systems such as hydraulic power, thermal power, wind power and solar power stations, and in various fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace, and the like. In the circulation process of the secondary battery, the negative electrode carbon material has volume expansion, pulverization of the material is brought, pole piece rebound is brought by the volume expansion of the material, the corners of the pole pieces are broken, the safety risk of the secondary battery is increased, meanwhile, the capacity is quickly attenuated due to the fact that the materials lose electrical contact with each other, and the circulation stability of the battery is poor. How to reduce the volume expansion of the cathode carbon material in the circulation process, reduce the rebound rate of the pole piece, and improve the circulation performance and the safety performance of the battery is a technical problem to be solved in the current secondary battery application field. Disclosure of Invention The present application has been made in view of the above problems, and an object of the present application is to provide a secondary battery, a negative electrode tab, and an electric device, in which the negative electrode tab of the secondary battery has a low rebound rate, and the secondary battery thus produced has excellent cycle performance and safety performance. In order to achieve the above object, a first aspect of the present application provides a secondary battery comprising a negative electrode tab including a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, the negative electrode film layer including a negative electrode active material including a carbon material; at least part of the surface of the carbon material is coated with fibers, and the rebound rate of the negative electrode plate is 20% -40%. In any embodiment, the rebound rate of the negative electrode plate is 25% -35%. In the scheme, the fiber is wound on the carbon material to bind the carbon material, so that the volume change of the carbon material in the process of removing and embedding active ions can be effectively restrained, the rebound rate of the pole piece is reduced, the possibility of fracture of the corner of the pole piece is reduced, the safety performance of the battery is improved, meanwhile, the pulverization phenomenon in the circulation process of the carbon material can be reduced, the laminating property between materials is improved, and therefore, the circulation stability of the pole piece is improved, and the service life of the battery is prolonged. In any embodiment, the carbon material comprises at least one of graphite, a hard carbon material. In any embodiment, the fibers have a tensile strength of 550MPa to 2500MPa. The tensile strength of the fiber is in a proper range, so that the aim of restraining the volume expansion of the matrix material can be fulfilled, the rebound rate of the pole piece is reduced, and the cycle performance and the safety performance of the battery are improved. In any embodiment, the fibers have a diameter of 10nm to 1000nm, alternatively 20nm to 150nm. The diameter of the fiber is in a proper range, so that the fiber has proper strength, the tight wrapping of the carbon material is realized, the aim of inhibiting the volume expansion of the carbon material is fulfilled, the rebound rate of the pole piece is reduced, and the cycle performance and the safety performance of the battery are improved. In any embodiment, the length of the fibers is 200nm-1mm, optionally 1 μm to 100 μm. The length of the fiber is in a proper range, so that the fiber can achieve the purposes of winding on a carbon material and inhibiting the volume expansion of the carbon material, the rebound rate of the pole piece is reduced, the cycle performance and the safety performance of the battery are improved, meanwhile, the negative electrode slurry has proper dispersibility and filterability, the process window of the negative electrode slurry and the negative electrode pole piece is widened, the uniformity of components such as a negative electrode active material, a conductive agent and the like in the negative electrode pole piece is improved, and the cycle performance of the battery is improved. In any embodiment, the mass content of the fiber is 0.1% -10%, optionally 0.5% -2%, based on the mass of the anode active material. The mass content of th