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CN-122011982-A - SBR adhesive and preparation method and application thereof

CN122011982ACN 122011982 ACN122011982 ACN 122011982ACN-122011982-A

Abstract

The invention belongs to the technical field of lithium ion battery materials, and particularly relates to an SBR adhesive, a preparation method and application thereof. The SBR adhesive comprises a core layer and a shell layer, wherein the core layer comprises main raw materials of butadiene, styrene and hydroxy acrylic ester, and the shell layer comprises main raw materials of isooctyl acrylate, beta-hydroxyethyl methacrylate, itaconic acid and N-vinyl pyrrolidone. The modified polymer is prepared by core layer prepolymerization, shell layer gradient polymerization and dynamic crosslinking modification. The SBR adhesive provided by the invention balances cohesive force and interfacial adhesion, and has the advantages of controllable preparation process and good repeatability. The SBR adhesive is used in the battery, so that the structural integrity and the cycling stability of the electrode are improved.

Inventors

  • LIU CHUNXIN
  • WANG XUAN
  • ZHANG ZHENGUO
  • WANG YANGANG
  • ZHANG ZHONGCHAO

Assignees

  • 山东瑞丰高分子材料股份有限公司

Dates

Publication Date
20260512
Application Date
20260415

Claims (10)

  1. 1. The SBR adhesive is characterized by comprising a core layer and a shell layer, wherein the core layer comprises main raw materials of butadiene, styrene and hydroxy acrylic ester, the shell layer comprises main raw materials of isooctyl acrylate, beta-hydroxyethyl methacrylate, itaconic acid and N-vinyl pyrrolidone, and the core layer and the shell layer also respectively comprise an emulsifier and an initiator.
  2. 2. The SBR adhesive according to claim 1, wherein the core layer comprises, by weight, 30-45 parts of butadiene, 25-35 parts of styrene and 5-10 parts of hydroxyacrylate.
  3. 3. The SBR adhesive according to claim 1, wherein the shell comprises, by weight, 10-20 parts of isooctyl acrylate, 3-8 parts of beta-hydroxyethyl methacrylate, 2-5 parts of itaconic acid and 1-4 parts of N-vinyl pyrrolidone.
  4. 4. The SBR adhesive of claim 1, wherein the emulsifier of the core layer is sodium dodecyl benzene sulfonate and fatty alcohol-polyoxyethylene ether are compounded according to a mass ratio of 1-3:1, and the emulsifier of the shell layer is sodium dodecyl sulfate.
  5. 5. The SBR adhesive of claim 1, wherein the initiator of the core layer and the initiator of the shell layer are ammonium persulfate or potassium persulfate.
  6. 6. A method for preparing the SBR adhesive of any of claims 1 to 5, comprising the steps of: (1) The preparation method comprises the steps of (1) pre-polymerizing a nuclear layer, namely dissolving an emulsifying agent in water, adding butadiene, styrene and hydroxy acrylic ester to obtain a pre-emulsion, heating, carrying out heat preservation seed polymerization on part of the pre-emulsion and part of an aqueous solution of an initiator, dropwise adding the rest of the pre-emulsion and the rest of the initiator, and carrying out heat preservation after the dropwise adding is finished to obtain a nuclear layer latex; (2) Dissolving isooctyl acrylate and beta-hydroxyethyl methacrylate in an emulsifier to obtain a pre-emulsion A, dissolving itaconic acid and N-vinyl pyrrolidone in the emulsifier, adding an initiator aqueous solution to obtain a solution B, dropwise adding the pre-emulsion A into the nuclear layer latex solution obtained in the step (1), carrying out heat preservation reaction, and dropwise adding the solution B for heat preservation reaction to obtain the functionalized SBR latex particles; (3) And (3) dynamic crosslinking modification, namely regulating the pH value of the functionalized SBR latex particles to 6.5-7.5, dropwise adding a dynamic crosslinking agent ethanol solution, carrying out heat preservation reaction, and carrying out aftertreatment to obtain the SBR adhesive.
  7. 7. The method of claim 6, wherein the dynamic cross-linking agent is a condensation product of 3, 5-dihydroxyphenylboronic acid and ethylene glycol diglycidyl ether.
  8. 8. The method for preparing SBR adhesive according to claim 7, wherein the addition amount of the dynamic cross-linking agent is 2-8wt% of dry weight of the functionalized SBR latex particles.
  9. 9. The method for preparing SBR adhesive according to claim 6, wherein the reaction temperature of the core layer is 75-85 ℃, the reaction temperature of the shell layer gradient polymerization is 65-75 ℃, and the reaction temperature of the dynamic crosslinking modification is 40-50 ℃.
  10. 10. The SBR adhesive of any one of claims 1 to 5, wherein the SBR adhesive is used for preparing a positive electrode and/or a negative electrode of a lithium ion battery, the addition amount of the SBR adhesive is 2-8wt% of the mass of an active material, the active material of the negative electrode is Si, siO, si/C or a graphite-silicon composite material, and the active material of the positive electrode is NCM811, NCM90100 or lithium iron phosphate.

Description

SBR adhesive and preparation method and application thereof Technical Field The invention belongs to the technical field of lithium ion battery materials, and particularly relates to an SBR adhesive, a preparation method and application thereof. Background In the process of upgrading the lithium ion battery to high energy density, a silicon-based negative electrode and a high-nickel ternary positive electrode become a key material system, but the electrode brings along remarkable volume effect and interface stress in charge-discharge cycle, and the composite requirements of high cohesion, strong adhesion, dynamic self-adaption and high-temperature stability are provided for the aqueous adhesive. Styrene Butadiene Rubber (SBR) is the main choice of the water-based binder of the negative electrode by virtue of the advantages of low cost, good dispersibility, moderate bonding strength and the like, and is widely applied to the preparation of graphite, silicon-based and ternary system electrodes. However, the conventional SBR adhesive has inherent contradiction that cohesive force and cohesiveness are difficult to be compatible, namely, the brittleness of the pole piece is increased and the flexibility is reduced due to the fact that the crosslinking density is simply increased, and the pole piece is easy to fall off powder and insufficient in peeling strength due to the fact that the crosslinking density is reduced. Meanwhile, the traditional SBR molecular chain lacks a functional group capable of dynamically responding, the cross-linked network is of a static irreversible structure, microcracks generated in the circulation process cannot be repaired, stress concentration caused by large-scale volume expansion of the silicon-based negative electrode is difficult to buffer, and electrode breakage, pulverization and shedding are easy to cause. In addition, SBR is easy to swell and degrade under the working conditions of high temperature and high voltage, so that the electrode structure is invalid, the battery circulation and the safety performance are attenuated, and the large-scale application of the SBR in the high-energy-density lithium ion battery is severely limited. In order to improve the properties of SBR binders, a great deal of modification studies have been carried out in the prior art. For example, CN113555558A discloses a core-shell structure SBR latex adhesive, the adhesive and mechanical properties are improved through the design of a core layer high cohesive chain segment and a shell layer polar functional group, but the shell layer is of a conventional copolymerization structure, a gradient grafting strategy is not adopted, continuous transition from flexible adhesive to polar anchoring cannot be realized, interface suitability is still insufficient, a dynamic crosslinking network is not constructed only by means of hydrogen bond and physical entanglement, and self-repairing and stress relaxation capabilities are limited. CN121555116a proposes a self-healing polyacrylic acid binder based on dynamic borate bond, and utilizes boric acid-hydroxyl reversible reaction to realize network repair, but its matrix is polyacrylic acid system, not core-shell structure SBR, and has the problems of poor compatibility with electrode slurry, insufficient flexibility, poor processability, etc., and the interface and body performance are synergistically optimized without combining gradient grafting structure. The prior SBR modification technology has the defects that the core-shell structure is mainly formed by two-stage simple copolymerization, gradient grafting design is lacked, cohesive force, cohesiveness and interface gradient adaptability cannot be balanced synchronously, a crosslinking system mainly adopts static covalent bonds or physical effects, a reversible dynamic crosslinking network does not exist, self-repairing and stress self-adaption capabilities are not provided, the matching performance of a functional monomer and a crosslinking agent is poor, the stability is insufficient at high temperature and high voltage, and the long-term service requirements of a silicon-based anode and a high-nickel anode are difficult to meet. Disclosure of Invention The technical problem to be solved by the invention is to overcome the defects in the prior art, and provide the SBR adhesive and the preparation method thereof, wherein the prepared SBR adhesive balances cohesive force and interfacial adhesion, and the preparation method has controllable process and good repeatability. The invention also provides application of the SBR adhesive, and the structural integrity and the cycling stability of the electrode are improved. The SBR adhesive comprises a core layer and a shell layer, wherein the core layer comprises main raw materials of butadiene, styrene and hydroxy acrylic ester, and the shell layer comprises main raw materials of isooctyl acrylate, beta-hydroxyethyl methacrylate, itaconic acid and N-vinyl pyrroli