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CN-121991632-A - Negative electrode binder, secondary battery, and electricity device

CN121991632ACN 121991632 ACN121991632 ACN 121991632ACN-121991632-A

Abstract

The application provides a negative electrode binder, a secondary battery and an electric device, and belongs to the technical field of battery materials. The negative electrode binder of the present application comprises a hydroxyl group, a carboxyl group, an amino group, an ester group and a benzene ring structure, and the use of the negative electrode binder comprising a hydroxyl group, a carboxyl group, an amino group, an ester group and a benzene ring structure for a secondary battery can improve the cycle performance and the rate capability of the secondary battery.

Inventors

  • SHEN WENBIN
  • LIU XIANG
  • LEI JING

Assignees

  • 欣旺达动力科技股份有限公司

Dates

Publication Date
20260508
Application Date
20260115

Claims (14)

  1. 1. A negative electrode binder, characterized in that the negative electrode binder comprises a hydroxyl group, a carboxyl group, an amino group, an ester group, and a benzene ring structure.
  2. 2. The negative electrode binder according to claim 1, wherein the molar ratio of the hydroxyl group to the benzene ring is 1 (0.04 to 0.36).
  3. 3. The anode binder of claim 1, wherein the anode binder has the structural formula: , wherein m=3000 to 10000.
  4. 4. The negative electrode binder of claim 1, wherein the negative electrode binder has a tensile strength of 2.8-3.6 mpa and a strain of 18-24%.
  5. 5. The anode binder of claim 1, wherein the anode binder is formed mainly from polymerization of gamma-polyglutamic acid, para-aminobiphenyl, gallic acid, and sorbitol.
  6. 6. The negative electrode binder according to claim 5, wherein a molar ratio of the gamma-polyglutamic acid to the p-aminobiphenyl is 1 (0.05 to 0.35); and/or the molar ratio of the gamma-polyglutamic acid to the gallic acid is 1 (0.02-0.25); and/or the molar ratio of the gamma-polyglutamic acid to the sorbitol is 1 (0.02-0.18); and/or the molecular weight of the gamma-polyglutamic acid is 70-200 ten thousand.
  7. 7. A secondary battery comprising a negative electrode tab, wherein the negative electrode tab comprises a negative electrode current collector and a negative electrode active layer disposed on at least one side surface of the negative electrode current collector, the negative electrode active layer comprising a binder, the binder comprising the negative electrode binder of any one of claims 1-6.
  8. 8. The secondary battery of claim 7, wherein the binder further comprises a second binder comprising at least one of PAA, CMC, SBR, PVDF.
  9. 9. The secondary battery according to claim 8, wherein the second binder comprises CMC and SBR.
  10. 10. The secondary battery according to claim 9, wherein the mass percentage of the negative electrode binder is 60 to 80%, the mass percentage of the CMC is 10 to 20%, and the mass percentage of the SBR is 15 to 25%, based on the mass of the binder.
  11. 11. The secondary battery according to claim 10, wherein in the negative electrode tab, the SBR is more than the CMC in mass percentage.
  12. 12. The secondary battery according to claim 7, wherein the anode active layer further comprises an anode active material, the anode active material comprising a silicon-based material.
  13. 13. The secondary battery according to any one of claims 7 to 11, wherein the mass percentage of the binder is 3% to 8% based on the mass of the anode active layer.
  14. 14. An electric device comprising the secondary battery according to any one of claims 7 to 13.

Description

Negative electrode binder, secondary battery, and electricity device Technical Field The application relates to the technical field of battery materials, in particular to a negative electrode binder, a secondary battery and an electric device. Background In recent years, with the increasing severity of energy crisis and environmental pollution problems, the development of new energy technologies has received widespread attention worldwide. Among many new energy technologies, secondary batteries have become a hot spot for research and application due to their advantages of high energy density, long life, no memory effect, and the like. However, conventional graphite anode materials have approached the limit of their theoretical capacity and have failed to meet the increasing high energy density requirements. Therefore, the silicon-based anode material is an ideal choice for replacing graphite because of its high theoretical specific capacity (about 4200mAh/g, ten times more than that of graphite). However, silicon-based anode materials undergo significant volume changes during charge and discharge, which results in destruction of the electrode structure and degradation of cycle performance. In the secondary battery, the adhesive can bond the active substance (such as silicon-based anode material) and the conductive agent with the current collector, thereby reducing the adverse effect on the pole piece caused by the volume change in the process of removing and inserting lithium from the electrode material and stabilizing the internal structure of the pole piece. The commonly used silicon-based negative electrode binder mainly comprises CMC (carboxymethyl cellulose), PAA (polyacrylic acid), PVDF (polyvinylidene fluoride) and the like, the acting force between the PVDF and silicon particles is weak, and when the volume of the silicon particles is obviously expanded, the PVDF binder is easily damaged, so that the electrode structure is unstable, and the cycle performance of a battery is further influenced. The CMC contains a rigid six-membered heterocyclic structure in the molecular chain, resulting in relatively poor flexibility of CMC. In the charge and discharge process of the battery, the rigid structure easily causes the pole piece to crack, thereby influencing the cycle stability of the battery. The PAA has the advantages that the PAA has larger brittleness, a polymer chain is fragile, the PAA is easy to break in the charge and discharge process of the battery, once the PAA binder is subjected to the action of external force, the PAA binder is easy to permanently deform, active substances are agglomerated, the capacity exertion of the active substances is influenced, the rate performance of the battery is reduced, and the cycle stability of the battery is also adversely affected. Disclosure of Invention The application aims to overcome the defects of the prior art and provides a negative electrode binder, a secondary battery and an electric device. In order to achieve the purpose, the application adopts the technical scheme that in the first aspect, the negative electrode binder is provided, and the negative electrode binder comprises hydroxyl, carboxyl, amino, ester and benzene ring structures. In some embodiments, the molar ratio of the hydroxyl groups to the benzene rings is 1 (0.04-0.36). In some embodiments, the negative electrode binder has the following structural formula: , wherein m=3000 to 10000. In some embodiments, the tensile strength of the negative electrode binder is 2.8-3.6 mpa and the strain is 18-24%. In some embodiments, the negative electrode binder is formed from polymerization of gamma-polyglutamic acid, para-aminobiphenyl, gallic acid, and sorbitol. In some embodiments, the molar ratio of the gamma-polyglutamic acid to the para-aminobiphenyl is 1 (0.05-0.35). In some embodiments, the molar ratio of the gamma-polyglutamic acid to the para-aminobiphenyl is 1 (0.02-0.25). In some embodiments, the molar ratio of the gamma-polyglutamic acid to the sorbitol is 1 (0.02-0.18). In some embodiments, the molecular weight of the gamma-polyglutamic acid is 70-200 ten thousand. In a second aspect, a secondary battery is provided, including a negative electrode tab including a negative electrode current collector and a negative electrode active layer disposed on at least one side surface of the negative electrode current collector, the negative electrode active layer including a binder, the binder including the negative electrode binder. In some embodiments, the adhesive further comprises a second adhesive comprising at least one of PAA, CMC, SBR, PVDF. In some embodiments, the second binder comprises CMC and SBR. In some embodiments, the negative electrode binder is 60-80% by mass, the CMC is 5-20% by mass, and the SBR is 15-25% by mass, based on the mass of the binder. In some embodiments, in the negative electrode tab, the SBR is present in a mass percent greater than the CMC. In some embodimen