Search

CN-122000298-A - Negative plate, preparation method thereof, battery and power utilization device

CN122000298ACN 122000298 ACN122000298 ACN 122000298ACN-122000298-A

Abstract

The application provides a negative plate, a preparation method thereof, a battery and an electric device, wherein the negative plate comprises a negative current collector and a negative active layer positioned on the surface of the negative current collector, the negative electrode active layer includes a negative electrode active material, a binder, and a conductive agent, wherein the binder includes an aqueous polyurethane binder and a three-dimensional network polymer binder having an ester group. The negative plate comprises a three-dimensional network polymer binder with ester groups and a water-based polyurethane binder, so that the binder has high binding force, excellent mechanical strength and flexibility, and can effectively improve the problem of volume expansion of an active material, and further the corresponding battery has high capacity, high initial efficiency and long cycle performance.

Inventors

  • MENG CHAO
  • JIANG YONG
  • Ling Peiquan
  • WANG QUNFENG
  • GU XIAOYU
  • LI JIN

Assignees

  • 广汽埃安新能源汽车股份有限公司

Dates

Publication Date
20260508
Application Date
20260305

Claims (13)

  1. 1. The negative electrode plate is characterized by comprising a negative electrode current collector and a negative electrode active layer positioned on the surface of the negative electrode current collector, wherein the negative electrode active layer comprises a negative electrode active material, a binder and a conductive agent, and the binder comprises an aqueous polyurethane binder and a three-dimensional network polymer binder with an ester group.
  2. 2. The negative electrode sheet according to claim 1, wherein the negative electrode active material comprises a silicon-based material, the aqueous polyurethane binder is a linear aqueous polyurethane binder, and the aqueous polyurethane binder is interposed in the three-dimensional network polymer binder.
  3. 3. The negative plate according to claim 2, wherein the mass ratio of the aqueous polyurethane binder to the three-dimensional network polymer binder is (1.5-2.5): 3, or/and the molecular weight of the aqueous polyurethane binder is 20000-100000.
  4. 4. The negative electrode sheet of claim 2, wherein the three-dimensional network polymer binder comprises a first polymer binder comprising at least one of polyacrylic acid, polymethacrylic acid, and polyglutamic acid, and a second polymer binder comprising at least one of carboxymethyl cellulose, polyvinyl alcohol, and sodium alginate.
  5. 5. The negative electrode sheet according to claim 4, wherein the first polymer binder is selected from the group consisting of polyacrylic acid and has a molecular weight of 100000 to 300000, and the second polymer binder is selected from the group consisting of carboxymethyl cellulose and has a molecular weight of 400000 to 650000.
  6. 6. The negative electrode sheet according to claim 4, wherein the mass ratio of the first polymer binder to the second polymer binder is (0.8 to 1.2): 1.
  7. 7. The negative electrode sheet according to any one of claims 1 to 6, wherein a mass ratio of the negative electrode active material to the binder is (90 to 95): 4 to 6, or/and a mass ratio of the negative electrode active material to the conductive agent is (90 to 95): 1 to 2.
  8. 8. The method for preparing the negative electrode sheet according to any one of claims 1 to 7, comprising the steps of: Mixing a negative electrode active material, a first polymer binder with carboxyl, a second polymer binder with hydroxyl, a linear aqueous polyurethane binder, a conductive agent and water, wherein the negative electrode active material comprises a silicon-based material, so as to obtain negative electrode slurry; And then carrying out heat treatment on the negative plate intermediate under vacuum condition to enable the first polymer binder and the second polymer binder to be in-situ crosslinked to form the three-dimensional network polymer binder, and synchronously enabling the aqueous polyurethane binder to be inserted into the formed three-dimensional network polymer binder to obtain the negative plate.
  9. 9. The method according to claim 8, further comprising, before the step of performing the heat treatment, performing a drying treatment on the negative electrode sheet intermediate, wherein the temperature of the drying treatment is less than the temperature of the heat treatment to remove moisture in the negative electrode sheet intermediate.
  10. 10. The method according to claim 9, wherein the treatment temperature is 50 ℃ to 80 ℃ during the drying treatment, and the treatment temperature is 110 ℃ to 140 ℃ during the heat treatment.
  11. 11. The method according to any one of claims 8 to 10, wherein the first polymer binder is selected from polyacrylic acid, the second polymer binder is selected from carboxymethyl cellulose, and the step of mixing treatment includes: Dissolving the carboxymethyl cellulose in water to obtain carboxymethyl cellulose solution; Adding the polyacrylic acid, the aqueous polyurethane binder and the conductive agent into the carboxymethyl cellulose solution and mixing to obtain a slurry intermediate; and adding the anode active material into the slurry intermediate and mixing to obtain anode slurry.
  12. 12. A battery comprising the negative electrode sheet according to any one of claims 1 to 7.
  13. 13. An electrical device comprising the battery of claim 12.

Description

Negative plate, preparation method thereof, battery and power utilization device Technical Field The application relates to the technical field of battery manufacturing, in particular to a negative plate, a preparation method thereof, a battery and an electric device. Background At present, the cathode active material has large volume change in the charge and discharge process, especially the silicon-based material with ultrahigh theoretical specific capacity, which is easy to cause pulverization of the material, so that irreversible attenuation is generated in the electrode capacity, and the comprehensive electrical performance of the corresponding battery is poor. Based on this, the skilled artisan has conceived the problem of improving the volume expansion of the material from the binder level, specifically, the existing conventional binders are capable of forming hydrogen bonds or covalent bonds with the active material, etc., thereby improving the volume expansion of the active material to some extent, but the improvement effect of these conventional binders is poor, so that the capacity, initial efficiency, cycle performance, etc. of the corresponding battery are still poor. Disclosure of Invention The application aims to provide a negative plate, a preparation method thereof, a battery and an electric device, wherein the negative plate comprises a three-dimensional network polymer binder with ester groups and a water-based polyurethane binder, so that the binder has high binding force, excellent mechanical strength and flexibility, and can effectively improve the problem of volume expansion of an active material, thereby enabling a corresponding battery to have high capacity, high initial efficiency and long cycle performance. Embodiments of the present application are implemented as follows: In a first aspect, an embodiment of the present application provides a negative electrode sheet, where the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer located on a surface of the negative electrode current collector, and the negative electrode active layer includes a negative electrode active material, a binder, and a conductive agent, where the binder includes an aqueous polyurethane binder and a three-dimensional network polymer binder having an ester group. In the technical scheme, the binder in the negative plate comprises the aqueous polyurethane binder and the three-dimensional network polymer binder with the ester group, wherein the three-dimensional network polymer binder with the ester group has high binding power, excellent mechanical strength and deformation resistance, the aqueous polyurethane binder has high binding power and high flexibility, the composite binder formed by the two binders has high binding power, excellent mechanical strength and flexibility, and the problem of volume expansion of an active material can be effectively improved, so that a corresponding battery has high capacity, high first efficiency and long cycle performance. In some alternative embodiments, the negative electrode active material comprises a silicon-based material, the aqueous polyurethane binder is a linear aqueous polyurethane binder, and the aqueous polyurethane binder is interspersed with the three-dimensional network polymer binder. In the technical scheme, the problem of volume expansion of the silicon-based material in the charge and discharge process is serious, the silicon-based material and the composite binder are matched for use, the problem of serious volume expansion of the silicon-based material can be effectively solved, a battery corresponding to a material system has high capacity, high initial efficiency and long cycle performance, in addition, the binder is a linear aqueous polyurethane binder and is inserted into a three-dimensional network polymer binder, the composite binder forms a semi-interpenetrating network-like structure, and the composite binder with the structural characteristics has higher binding force, excellent mechanical strength and flexibility, so that the problem of serious volume expansion of the silicon-based active material is further improved. In some alternative embodiments, the mass ratio of the aqueous polyurethane binder to the three-dimensional network polymer binder is (1.5-2.5): 3, or/and the molecular weight of the aqueous polyurethane binder is 20000-100000. In the technical scheme, the mass ratio of the aqueous polyurethane binder to the three-dimensional network polymer binder is limited in the range, so that the aqueous polyurethane binder and the three-dimensional network polymer binder have proper mass ratio, the corresponding binder has proper mechanical strength and flexibility, and the problem of volume expansion of the silicon-based material is better improved, the molecular weight of the aqueous polyurethane is limited in the range, and the composite binder has excellent flexibility when