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CN-121983546-A - Negative plate, battery and battery pack

CN121983546ACN 121983546 ACN121983546 ACN 121983546ACN-121983546-A

Abstract

The embodiment of the application provides a negative plate, a battery and a battery pack, and relates to the technical field of secondary batteries. The negative electrode sheet includes a current collector, a tab connected to one side of the current collector, a first active material layer, and a second active material layer. The first active material layer is coated on the front and back surfaces of the current collector, and the thickness of the first active material layer from one side of the tab to one side far away from the tab is gradually thickened and then gradually thinned. The second active material layer is coated on the outer side of the first active material layer, and the second active material layer extends from one side of the tab to one side far away from the tab, gradually thins in thickness and then gradually thickens. The particle size distribution of the first active material layer is larger than that of the second active material layer. The application can solve the problem of lithium precipitation of the negative electrode plate.

Inventors

  • LIU JIAN
  • HUANG HAINING

Assignees

  • 兰钧新能源科技有限公司

Dates

Publication Date
20260505
Application Date
20231113

Claims (10)

  1. 1. A negative electrode sheet, comprising: A current collector (110); A tab (130) connected to one side of the current collector (110), the tab (130) being configured to be electrically connected to a post of an electrical core; The first active material layer (150), the first active material layer (150) coats the front and back of the current collector (110), and the thickness of the first active material layer (150) from one side of the tab (130) to one side far away from the tab (130) is gradually thickened and then gradually thinned; And a second active material layer (170), the second active material layer (170) being coated on the outer side of the first active material layer (150), and the second active material layer (170) extending from one side of the tab (130) toward the side far from the tab (130) and having a thickness that gradually becomes thinner and then thicker; The first active material layer (150) has a particle size distribution greater than that of the second active material layer (170).
  2. 2. The negative electrode sheet according to claim 1, wherein the second active material layer (170) has a higher degree of graphitization than the first active material layer (150) and a larger specific surface area.
  3. 3. The negative electrode sheet according to claim 1, wherein the first active material layer (150) is a high specific energy active material layer, and the second active material layer (170) has a kinetic property that is greater than that of the first active material layer (150).
  4. 4. The negative electrode sheet according to claim 1, wherein the slurry of the first active material layer (150) is prepared by blending graphite with small particles, a binder, a conductive agent and a first solvent in a certain proportion, and the slurry of the second active material layer (170) is prepared by blending graphite with small particles, a binder, a conductive agent and a second solvent in a certain proportion.
  5. 5. The negative electrode sheet according to claim 1, wherein the thickness of the first active material layer (150) and the sum of the thicknesses of the second active material layers (170) are equal at any position of the current collector (110).
  6. 6. The negative electrode sheet according to claim 1, wherein a ratio of a thickness of the first active material layer (150) to a thickness of the second active material layer (170) is X, and a value of X is 0<X≤10.
  7. 7. The negative electrode sheet according to claim 6, wherein X gradually increases from a side of the tab (130) toward a side away from the tab (130) and gradually decreases again.
  8. 8. The negative electrode sheet according to claim 1 or 2, characterized in that the first active material layer (150) and the second active material layer (170) are of an asymmetric structure in the extending direction of the tab (130).
  9. 9. A battery comprises a shell (310), a bare cell and a pole (330), and is characterized in that, The bare cell comprises a positive plate, a diaphragm and the negative plate of any one of claims 1-8; The positive plate, the diaphragm, the negative plate and the diaphragm are sequentially laminated; The bare cell is mounted in the shell (310), and the tab (130) is electrically connected with the pole (330).
  10. 10. A battery pack comprising a plurality of the batteries of claim 9, a plurality of the batteries being connected in parallel or in series.

Description

Negative plate, battery and battery pack The invention is a divisional application of patent application with the application number 2023115065826, the application date 2023, 11 and 13 and the invention name of 'negative plate, battery and battery pack'. Technical Field The invention relates to the field of secondary batteries, in particular to a negative plate, a battery and a battery pack. Background Secondary batteries, also called rechargeable batteries or secondary batteries, are batteries that can be used continuously by activating active materials by charging after the battery is discharged. By utilizing the reversibility of chemical reactions, a new battery can be built, namely, after one chemical reaction is converted into electric energy, the chemical system can be repaired by using the electric energy, and then the chemical reaction is converted into the electric energy. Is widely applied to new energy automobiles, energy storage equipment and the like. Along with the development of quick charge technology, when the existing lithium battery is charged at a high rate, metal lithium deposition is easy to occur on the side of the negative electrode tab corresponding to the positive electrode tab and the negative electrode tab, lithium dendrite is easier to form, and then the risk of thermal runaway of the battery is possibly increased. Disclosure of Invention The object of the present invention includes, for example, providing a negative electrode sheet, a battery, and a battery pack, which can improve the problem of lithium precipitation of the negative electrode sheet. Embodiments of the invention may be implemented as follows: in a first aspect, the present application provides a negative electrode sheet comprising: A current collector; The electrode lug is connected to one side of the current collector and is used for being electrically connected with the electrode post of the battery cell; The first active material layer is coated on the front surface and the back surface of the current collector, and the thickness of the first active material layer from one side of the tab to one side far away from the tab is gradually thickened and then gradually thinned; And a second active material layer coated on the outer side of the first active material layer, wherein the second active material layer extends from one side of the tab to one side far away from the tab, and the thickness of the second active material layer is gradually thinned and then gradually thickened; The first active material layer has a particle size distribution greater than that of the second active material layer. In an alternative embodiment, the second active material layer (170) has a higher degree of graphitization than the first active material layer and a larger specific surface area. In an alternative embodiment, the first active material layer is a high specific energy active material layer, and the second active material layer has a kinetic property that is greater than the kinetic property of the first active material layer. In an alternative embodiment, the slurry of the first active material layer is prepared by blending graphite with particles, a binder, a conductive agent and a first solvent according to a certain proportion, and the slurry of the second active material layer is prepared by blending graphite with particles, a binder, a conductive agent and a second solvent according to a certain proportion. In an alternative embodiment, the thickness of the first active material layer is equal to the sum of the thicknesses of the second active material layer at any position of the current collector. In an alternative embodiment, the ratio of the thickness of the first active material layer to the thickness of the second active material layer is X, and the value range of X is 0<X-10. In an alternative embodiment, the X gradually increases from the side of the tab toward the side away from the tab, and then gradually decreases. In an alternative embodiment, the first active material layer and the second active material layer have an asymmetric structure in the extending direction of the tab. In a second aspect, the present embodiment further provides a battery, including a housing, a bare cell, and a post, where the bare cell includes a positive electrode sheet, a separator, and a negative electrode sheet according to any one of the foregoing optional embodiments; The positive plate, the diaphragm, the negative plate and the diaphragm are sequentially laminated; the bare cell is installed in the shell, and the tab is electrically connected with the pole. In a third aspect, the present embodiment further provides a battery pack including a plurality of the batteries described in the above alternative embodiments, and a plurality of the batteries are connected in parallel or in series. The negative plate, the battery and the battery pack provided by the embodiment of the invention have the beneficial effects that: Accor