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CN-122025632-A - Battery cell, battery device and electricity utilization device

CN122025632ACN 122025632 ACN122025632 ACN 122025632ACN-122025632-A

Abstract

The application relates to the technical field of batteries, in particular to a battery cell, a battery device and an electric device, wherein the battery cell 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 surface of the negative electrode current collector, the negative electrode film layer comprises an adhesive, the negative electrode film layer sequentially comprises a first negative electrode film layer to an n-th negative electrode film layer from the direction away from the negative electrode current collector to the direction close to the negative electrode current collector, n is a positive integer greater than or equal to 2, and the mass ratio of the adhesive in the n-1-th negative electrode film layer is smaller than the mass ratio in the n-th negative electrode film layer. The negative pole piece has low full charge rebound rate and is suitable for the battery cells with high energy density and high group margin.

Inventors

  • ZHENG SONGHAI
  • TANG DAICHUN

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20241112

Claims (16)

  1. 1. The battery cell is characterized by comprising 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 surface of the negative electrode current collector; the negative electrode film layer comprises a binder; The negative electrode film layer sequentially comprises a first negative electrode film layer, a second negative electrode film layer and a third negative electrode film layer from the direction away from the negative electrode current collector to the direction close to the negative electrode current collector, wherein n is a positive integer greater than or equal to 2; The mass ratio of the binder in the n-1 negative electrode film layer is smaller than that in the n negative electrode film layer.
  2. 2. The battery cell of claim 1, wherein the binder comprises one or more of a first binder, a second binder, optionally a first binder or a combination of a first binder and a second binder; wherein the first binder comprises polyacrylic acid compounds, and can be selected from polyacrylic acid compounds modified by carbon nano tubes; The second binder comprises any one or a combination of at least two of styrene-butadiene rubber, styrene-acrylic rubber or pure acrylic rubber.
  3. 3. The battery cell of claim 2, wherein the polyacrylic acid compound comprises any one or a combination of at least two of polyacrylic acid, polymethacrylic acid, polyacrylate, or acrylic acid type copolymer.
  4. 4. The battery cell according to any one of claims 1 to 3, wherein the total mass of the binder is greater than 0% and equal to or less than 8% based on 100% of the total mass of the negative electrode film layer.
  5. 5. The battery cell according to any one of claims 2 to 4, wherein the binder comprises a first binder, and the negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer in sequence from a direction away from the negative electrode current collector to a direction close to the negative electrode current collector; the mass content of the first binder is more than 0% and less than or equal to 3% based on the mass of the first negative electrode film layer; the mass content of the first binder is greater than 0% and less than or equal to 5% based on the mass of the second anode film layer.
  6. 6. The battery cell of any one of claims 2-5, wherein the binder comprises a combination of a first binder and a second binder; The negative electrode film layer sequentially comprises a first negative electrode film layer, a second negative electrode film layer and a third negative electrode film layer from the direction away from the negative electrode current collector to the direction close to the negative electrode current collector, wherein n is a positive integer greater than or equal to 2; The mass ratio of the first binder in the n-1 negative electrode film layer is smaller than that of the first binder in the n negative electrode film layer.
  7. 7. The battery cell according to claim 6, wherein the total mass of the first binder is greater than 0% and equal to or less than 3.5% based on 100% of the total mass of the negative electrode film layer; The total mass of the second binder is more than 0% and less than or equal to 4.5%.
  8. 8. The battery cell according to claim 6 or 7, wherein the negative electrode film layer sequentially comprises a first negative electrode film layer and a second negative electrode film layer from a direction away from the negative electrode current collector to a direction close to the negative electrode current collector; based on the mass of the first negative electrode film layer, the mass content of the first binder is more than 0% and less than or equal to 1%, and the mass content of the second binder is more than 0% and less than or equal to 3%; Based on the mass of the second negative electrode film layer, the mass content of the first binder is more than 0% and less than or equal to 2%, and the mass content of the second binder is more than 0% and less than or equal to 3%.
  9. 9. The battery cell of any one of claims 1-8, wherein the negative electrode film further comprises a conductive agent having a mass ratio in the n-1 negative electrode film that is greater than the mass ratio in the n-th negative electrode film.
  10. 10. The battery cell according to claim 9, wherein the total mass of the conductive agent is greater than 0% and equal to or less than 2% based on 100% of the total mass of the negative electrode film layer.
  11. 11. The battery cell according to claim 9 or 10, wherein the negative electrode film layer sequentially comprises a first negative electrode film layer and a second negative electrode film layer from a direction away from the negative electrode current collector to a direction close to the negative electrode current collector; Based on the mass of the first negative electrode film layer, the mass content of the conductive agent is more than 0% and less than or equal to 1.2%; The mass content of the conductive agent is greater than 0% and less than or equal to 0.8% based on the mass of the second negative electrode film layer.
  12. 12. The battery cell of any one of claims 1-11, wherein the negative electrode tab has a full charge bounce rate of less than 20%, optionally 8% -15%.
  13. 13. The battery cell of any one of claims 1-12, wherein the battery cell has a shell group entry margin of 91% -95%.
  14. 14. The battery cell of any one of claims 1-13, wherein the negative current collector comprises a polymeric material base layer and a metal layer disposed on at least one surface of the polymeric material base layer.
  15. 15. A battery device, characterized in that it comprises a plurality of battery cells according to any one of claims 1-14.
  16. 16. An electrical device comprising a battery cell according to any one of claims 1 to 14, or a battery device according to claim 15.

Description

Battery cell, battery device and electricity utilization device Technical Field The application relates to the field of batteries, in particular to a battery cell, a battery device and an electricity utilization device. Background The battery monomer is widely applied in a plurality of fields, and in the prior art, the full-charge rebound rate of the negative electrode plate of the battery monomer is higher, and the battery monomer cannot be suitable for the battery monomer with high shell group margin, so that the energy density of the battery monomer is influenced. Therefore, it is important to develop a battery cell that overcomes the above-described drawbacks. Disclosure of Invention In view of the above problems, the present application provides a battery cell, a battery device and an electric device, in which the negative electrode tab has a low full charge rebound rate, and is suitable for a battery cell with high energy density and high group margin. In a first aspect, the present application provides a battery cell comprising a negative electrode tab; the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector; the negative electrode film layer comprises a binder; The negative electrode film layer sequentially comprises a first negative electrode film layer, a second negative electrode film layer and a third negative electrode film layer from the direction away from the negative electrode current collector to the direction close to the negative electrode current collector, wherein n is a positive integer greater than or equal to 2; The mass ratio of the binder in the n-1 negative electrode film layer is smaller than that in the n negative electrode film layer. In the negative pole piece compacting process, under the same acting force, the pressure born by the n-th negative pole film layer (lower layer) is larger than the pressure born by the n-1-th negative pole film layer (upper layer), and the compacting rebound of the lower layer negative pole film layer is more serious than the compacting rebound of the upper layer negative pole film layer. In the technical scheme of the embodiment of the application, the mass ratio of the binder in each film layer is gradually increased from the direction from the negative electrode current collector to the direction from the negative electrode current collector, the binding force of the n-th negative electrode film layer (lower layer) is larger than that of the n-1-th negative electrode film layer (upper layer), and compared with the upper layer film layer with high binding force, the application adopts the lower layer film layer with high binding force, so that the rebound effect of the pole piece is more remarkable, the compaction rebound of the pole piece can be better reduced, the full charge rebound rate of the battery is favorably reduced, and the possibility is provided for the battery with high group margin and high energy density. In some embodiments, the binder comprises one or more of a first binder, a second binder, optionally a first binder or a combination of a first binder and a second binder; wherein the first binder comprises polyacrylic acid compounds, and can be selected from polyacrylic acid compounds modified by carbon nano tubes; The second binder comprises any one or a combination of at least two of styrene-butadiene rubber, styrene-acrylic rubber or pure acrylic rubber. In the technical scheme of the embodiment of the application, one or more of the first binder or the second binder can be selected according to the requirement. As an example, the binder is selected from a first binder, and the polyacrylic compound structure contains a large amount of carboxyl groups, which can interact with other components such as a negative electrode active material or a conductive agent, so that the binding force is strong, the full charge rebound rate of the negative electrode plate can be well reduced, the possibility is provided for providing a battery with high group margin and high energy density, and the binder is particularly suitable for the negative electrode plate which is easy to generate full charge rebound. As an example, the binder is selected from a combination of a first binder and a second binder, and the second binder has lower cost, and can partially replace the first binder with higher cost, and the two binders are matched with each other, so that the full charge rebound rate of the negative electrode plate can be reduced to a certain extent, and the possibility is provided for providing a battery with high group margin and high energy density, for example, the binder can be suitable for a high-silicon material system. The polyacrylic acid compound is a modified polyacrylic acid compound of a carbon nano tube, compared with an unmodified polyacrylic acid compound, the carbon nano tube modified polyacr