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CN-122011965-A - Adhesive and preparation method thereof, negative electrode slurry, negative electrode plate and battery

CN122011965ACN 122011965 ACN122011965 ACN 122011965ACN-122011965-A

Abstract

The invention provides a binder, a preparation method thereof, negative electrode slurry, a negative electrode plate and a battery. The adhesive comprises ester-based modified styrene-butadiene rubber, wherein the ester-based modified styrene-butadiene rubber comprises a main chain framework and a plurality of branched chains, the main chain framework is of a main chain structure of the styrene-butadiene rubber, and the branched chains are obtained by polymerizing acrylate monomers. The branched chain containing the ester group is grafted and introduced on the main chain of the styrene-butadiene rubber, so that a lithium ion transmission channel can be effectively constructed in the binder, the ion conductivity is improved, and the transmission of lithium ions is promoted.

Inventors

  • JIANG JUNJIE
  • PAN XUELING
  • ZHANG LIN

Assignees

  • 惠州亿纬动力电池有限公司

Dates

Publication Date
20260512
Application Date
20260204

Claims (14)

  1. 1. The adhesive is characterized by comprising ester-based modified styrene-butadiene rubber, wherein the ester-based modified styrene-butadiene rubber comprises a main chain skeleton and a plurality of branched chains connected with the main chain skeleton, the main chain skeleton is of a main chain structure of the styrene-butadiene rubber, and the branched chains are obtained by polymerizing acrylate monomers.
  2. 2. The adhesive according to claim 1, wherein the ester-based modified styrene-butadiene rubber is polymerized from the styrene-butadiene rubber and the acrylate monomer.
  3. 3. The adhesive of claim 1 or 2, wherein the acrylate monomer comprises at least one of butyl acrylate, methyl methacrylate, ethyl acrylate, hydroxyethyl methacrylate, glycidyl methacrylate.
  4. 4. The adhesive according to claim 1 or 2, wherein the glass transition temperature of the ester-based modified styrene-butadiene rubber is-15 ℃ to 5 ℃.
  5. 5. The adhesive according to claim 1 or 2, further comprising styrene-butadiene rubber, an emulsifier, a crosslinking agent and a dispersion medium, Optionally, based on the total mass of the styrene-butadiene rubber, the ester-based modified styrene-butadiene rubber, the emulsifier, and the cross-linking agent, comprising: 45% -90% of styrene-butadiene rubber; 5% -50% of ester-modified styrene-butadiene rubber; 0.5% -3% of emulsifying agent; 0.1-2% of cross-linking agent.
  6. 6. A method of preparing the adhesive of any one of claims 1 to 5, comprising: Uniformly dispersing acrylate monomers and emulsifying agents in a dispersing medium to obtain functional monomer emulsion; Mixing styrene-butadiene rubber emulsion with the functional monomer emulsion, adding an initiator into the mixture, and carrying out copolymerization reaction to obtain a polymer mixed solution containing ester-based modified styrene-butadiene rubber; And adding a cross-linking agent into the polymer mixed solution, and obtaining the binder after a cross-linking reaction.
  7. 7. The method of claim 6, further comprising adding a reducing agent to the polymer blend prior to adding the crosslinking agent to remove unreacted acrylate monomer, And/or, after the crosslinking reaction, adding an alkaline neutralizing agent into the mixed solution, and adjusting the pH to 6-8.
  8. 8. The method according to claim 6 or 7, characterized in that at least one of the following conditions is fulfilled: the mass ratio of the acrylate monomer to the styrene-butadiene rubber in the styrene-butadiene rubber emulsion is (1:5) - (1:1), The mass ratio of the acrylic ester monomer to the emulsifier is (5-30) (0.5-2); The solid content of the styrene-butadiene rubber emulsion is 40% -50%; The consumption of the cross-linking agent is 0.5% -3% of the total mass of the polymerizable monomers in the reaction system; the dosage of the initiator is 0.1% -1.0% of the total mass of the polymerizable monomers in the reaction system.
  9. 9. The method according to claim 6 or 7, wherein the temperature of the copolymerization reaction is 50-80 ℃ for 4-12 hours; And/or the temperature of the crosslinking reaction is 60-80 ℃ and the time is 1-3 hours.
  10. 10. The negative electrode slurry is characterized by comprising an active substance, a conductive agent, a first binder and a solvent, wherein the first binder is the binder according to any one of claims 1-5 or the binder prepared by the method according to any one of claims 6-9.
  11. 11. The anode slurry according to claim 10, wherein the solid content of the first binder is 35% to 45%.
  12. 12. The anode slurry according to claim 10 or 11, wherein the first binder is used in an amount of 1 to 3% based on the total weight of the remaining components of the anode slurry after the solvent is removed.
  13. 13. A negative electrode sheet comprising a current collector and a negative electrode active layer on at least one surface of the current collector, the negative electrode active layer being prepared from the negative electrode slurry according to any one of claims 10 to 12.
  14. 14. A battery comprising the negative electrode tab of claim 13.

Description

Adhesive and preparation method thereof, negative electrode slurry, negative electrode plate and battery Technical Field The invention relates to the technical field of batteries, in particular to a binder, a preparation method thereof, negative electrode slurry, a negative electrode plate and a battery. Background The current commonly used negative electrode binder is a Styrene Butadiene Rubber (SBR) system, but the binder of the system has technical defects and defects when facing to high-power application scenes, for example, the ion transmission efficiency of the traditional SBR binder is low, so that polarization is serious when a large current passes through, internal resistance is increased, and high-power performance is influenced. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a binder having a better ion conduction function, which is beneficial to reducing the internal resistance of the battery. In one aspect of the invention, the invention provides an adhesive. According to an embodiment of the invention, the adhesive comprises an ester-based modified styrene-butadiene rubber, wherein the ester-based modified styrene-butadiene rubber comprises a main chain skeleton and a plurality of branched chains connected with the main chain skeleton, the main chain skeleton is a main chain structure of the styrene-butadiene rubber, and the branched chains are obtained by polymerizing acrylate monomers. Therefore, by grafting and introducing a branched chain containing an ester group (-COOR) polar functional group on the main chain of the styrene-butadiene rubber, the ester group has a certain solvation effect on lithium ions (Li +), a lithium ion transmission channel can be effectively constructed in a binder, the ion conductivity is improved, the transmission of lithium ions is promoted, and the styrene-butadiene rubber is used in a battery. According to an embodiment of the present invention, the ester-based modified styrene-butadiene rubber is polymerized from the styrene-butadiene rubber and the acrylate monomer. According to an embodiment of the present invention, the acrylate monomer includes at least one of butyl acrylate, methyl methacrylate, ethyl acrylate, hydroxyethyl methacrylate, glycidyl methacrylate. According to the embodiment of the invention, the glass transition temperature of the ester-based modified styrene-butadiene rubber is-15 ℃ to 5 ℃. According to the embodiment of the invention, the adhesive further comprises styrene-butadiene rubber, an emulsifying agent, a cross-linking agent and a dispersing medium, and optionally, the adhesive comprises 45% -90% of styrene-butadiene rubber, 5% -30% of ester-modified styrene-butadiene rubber, 0.5% -2% of emulsifying agent and 0.1% -1% of cross-linking agent based on the total mass of the styrene-butadiene rubber, the ester-modified styrene-butadiene rubber, the emulsifying agent and the cross-linking agent. In another aspect of the invention, the invention provides a method of preparing the aforementioned binder. According to the embodiment of the invention, the method for preparing the bonding comprises the steps of uniformly dispersing acrylate monomers and emulsifying agents in a dispersing medium to obtain functional monomer emulsion, mixing styrene-butadiene rubber emulsion with the functional monomer emulsion, adding an initiator into the mixture to carry out copolymerization reaction to obtain polymer mixed solution containing ester modified styrene-butadiene rubber, and adding a cross-linking agent into the polymer mixed solution to carry out cross-linking reaction to obtain the bonding agent. According to the preparation method, the branched chain containing the ester group (-COOR) polar functional group is grafted and introduced on the main chain of the styrene-butadiene rubber, the ester group has a certain solvation effect on lithium ions (Li +), a lithium ion transmission channel can be effectively constructed in the binder, the ion conductivity is improved, the binder can be used in a battery, the quick charge performance and the high-rate discharge performance of the battery can be remarkably improved, meanwhile, the ester group-modified styrene-butadiene rubber can still keep the original high adhesive strength, flexibility and high elasticity of the styrene-butadiene rubber, in the ester group-modified styrene-butadiene rubber, the cross-linking of the branched chain is beneficial to constructing a network structure, so that the ester group-modified styrene-butadiene rubber can effectively buffer the volume change of a silicon-based material, the rebound of a pole piece is restrained, the stability of an electrode structure is improved, and compared with the unmodified styrene-butadiene rubber, the ester group-modified styrene-butadiene rubber can better wet electrolyte and promote th