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CN-122011981-A - High-viscosity SBR (styrene butadiene rubber) -based battery glue for lithium ion battery cathode and preparation method thereof

CN122011981ACN 122011981 ACN122011981 ACN 122011981ACN-122011981-A

Abstract

The invention belongs to the technical field of battery glue, and particularly relates to high-viscosity SBR-based battery glue for a lithium ion battery cathode and a preparation method thereof. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode comprises the following steps of mixing SBR emulsion, DVB, an emulsifying agent, a coupling agent and deionized water, emulsifying under the action of an initiator to obtain a nuclear layer pre-emulsion, heating and dropwise adding a functional layer mixed solution for reaction, dropwise adding a shell layer mixed solution for reaction, preserving heat for reaction, and finally cooling, regulating pH and filtering to obtain the SBR-based battery glue. The invention provides a preparation method of high-viscosity SBR-based battery glue for a lithium ion battery cathode, which adopts a segmented emulsion polymerization method, a core layer is crosslinked with SBR to form a stable framework through DVB, a shell layer is introduced with a modifier to act synergistically with nano silicon dioxide, the glue solution viscosity is obviously improved, the compatibility of the glue solution is further optimized, and the prepared SBR-based battery glue has high cohesiveness and high stability.

Inventors

  • LIU CHUNXIN
  • WANG YEFAN
  • JIAO SHUYUAN
  • ZHOU JIAN
  • CHEN CHAO

Assignees

  • 山东瑞丰高分子材料股份有限公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode is characterized by comprising the following steps of: (1) Mixing styrene-butadiene rubber emulsion, divinylbenzene, an emulsifier, a coupling agent and deionized water, adding an initiator, and stirring and emulsifying at 50-70 ℃ to obtain a nuclear layer pre-emulsion; (2) Heating the nuclear layer pre-emulsion in the step (1) to 65-75 ℃, adding a functional layer mixed solution containing hydroxyethyl methacrylate, methacrylic acid and an initiator, and carrying out heat preservation reaction for 0.5-1h after the dripping is finished; (3) After the reaction of the step (2), heating the reaction liquid to 75-85 ℃, adding a shell mixed liquid containing acrylate compounds, nano silicon dioxide dispersion liquid, a cross-linking agent and a modifier, and carrying out heat preservation reaction for 0.5-1h after the dripping is finished; (4) And (3) after the reaction is finished, cooling, regulating the pH of the system to be neutral by using an ammonia water solution with the concentration of 25-28wt.%, and filtering to obtain the high-viscosity SBR-based battery glue for the lithium ion battery cathode.
  2. 2. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode according to claim 1, wherein the emulsifier is sodium dodecyl sulfate, the coupling agent is vinyl trimethoxy silane A-171, the initiator is ammonium persulfate, and the initiator dosage in the step (1) is 0.3-0.5% of the total mass of the styrene-butadiene rubber emulsion and divinylbenzene.
  3. 3. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode, which is disclosed in claim 1, is characterized in that the core layer pre-emulsion comprises, by mass, 30-50 parts of styrene-butadiene rubber emulsion, 5-15 parts of divinylbenzene, 1-5 parts of emulsifier, 0.5-3 parts of coupling agent and 40-60 parts of deionized water.
  4. 4. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode according to claim 3, wherein the styrene-butadiene rubber emulsion is prepared by emulsion polymerization of styrene and butadiene, and the preparation process comprises the steps of adding 30-40 parts of styrene, 60-70 parts of butadiene, 2-5 parts of sodium dodecyl sulfate, 0.3-0.8 part of ammonium persulfate and 100-150 parts of deionized water into a reaction kettle according to parts by weight, stirring and emulsifying at 60-70 ℃, carrying out polymerization for 6-8 hours, cooling and filtering to obtain the styrene-butadiene rubber emulsion with the solid content of 45-50 wt%.
  5. 5. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode, which is disclosed in claim 1, is characterized in that the functional layer mixed solution in the step (2) comprises the following raw materials, by mass, 10-20 parts of hydroxyethyl methacrylate, 5-15 parts of methacrylic acid and 0.2-1 part of an initiator.
  6. 6. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode according to claim 1, wherein in the step (3), one or more of polyurethane dispersoid, phosphate plasticizer and antioxidant is/are added into the shell layer mixed solution, and the addition amount of the high-viscosity SBR-based battery glue is 1-5 parts by weight of polyurethane dispersoid, 0.5-3 parts by weight of phosphate plasticizer and 0.1-1 part by weight of antioxidant.
  7. 7. The method for preparing the high-viscosity SBR-based battery glue for the lithium ion battery cathode according to claim 1, wherein the acrylic ester compound is a mixture of butyl acrylate and 2, 2-trifluoroethyl acrylate, and the mass ratio of the butyl acrylate to the 2, 2-trifluoroethyl acrylate is (5-10): 1.
  8. 8. The method for preparing the high-viscosity SBR-based battery glue for the lithium ion battery cathode according to claim 1, wherein the modifier is methacryloxypropyl heptaisobutyl cage-shaped polysilsesquioxane, and the crosslinking agent is N-methylolacrylamide.
  9. 9. The preparation method of the high-viscosity SBR-based battery glue for the lithium ion battery cathode according to claim 1, wherein in the step (3), the raw materials comprise, by mass, 20-40 parts of an acrylic acid ester compound, 5-15 parts of a nano silicon dioxide dispersion liquid, 1-5 parts of a cross-linking agent and 0.5-3 parts of a modifying agent.
  10. 10. A high viscosity SBR-based battery paste for a negative electrode of a lithium ion battery, characterized by being prepared by the preparation method according to any one of claims 1 to 9.

Description

High-viscosity SBR (styrene butadiene rubber) -based battery glue for lithium ion battery cathode and preparation method thereof Technical Field The invention belongs to the technical field of battery glue, and particularly relates to high-viscosity SBR-based battery glue for a lithium ion battery cathode and a preparation method thereof. Background The lithium ion battery is used as a core carrier of new energy industry, is widely applied to the fields of new energy automobiles, energy storage systems, consumer electronics and the like, and the performance of the lithium ion battery directly determines the core competitiveness of downstream products. The cathode is used as a key electrode for realizing charge-discharge cycle of the lithium ion battery, and bears core functions of lithium ion intercalation and deintercalation and electron conduction, and cathode battery glue (also called as cathode binder) is an indispensable key auxiliary material in cathode preparation. The early-stage lithium ion battery cathode mainly adopts an oily binder polyvinylidene fluoride (PVDF), has good electrochemical stability, but has the defects of high cost, environment friendliness due to the use of an organic solvent (NMP), difficulty in adapting to the volume expansion of a silicon-based cathode and the like, and is gradually replaced by an aqueous binder. At present, an aqueous binder has become a mainstream of industry, and mainly comprises Styrene Butadiene Rubber (SBR), sodium carboxymethylcellulose (CMC), polyacrylic acid (PAA) and the like, wherein a CMC and SBR compound system is widely applied to a graphite negative electrode, and the advantages of environmental protection, low cost and good dispersibility are dominant in the market. The CN109638286A discloses a carboxymethyl cellulose-based binder suitable for a lithium battery and application thereof, the main components of the binder are sodium carboxymethyl cellulose, modified SBR-SiO 2 mucilage, tea saponin, a thickening agent and a diluent auxiliary agent, the diluent auxiliary agent permeates the sodium carboxymethyl cellulose to form a premix during preparation, then the modified SBR and the tea saponin are sequentially added and stirred at a high speed, and finally the thickening agent is added and stirred, the binder solves the problems of large particles, insufficient pole piece softness and more surface defects in the process of mixing the traditional sodium carboxymethyl cellulose with multiple components, has the characteristics of fine particle size and good intersolubility, can reduce the pole piece surface defects, improve the pole piece softness and avoid pole piece cracking, but the binder mainly depends on CMC as the thickening agent to regulate the rheological property of the glue solution, has a single tackifying mechanism and is difficult to meet the high-load negative electrode coating requirement, and meanwhile, the binder is mainly prepared in a physical blending or simple grafting mode through introducing SiO 2 to modify, and is lack of powerful chemical bond bridging, and the inorganic phase and organic phase are easy to separate in the process of high-temperature circulation of the battery, so that a colloid network collapses. CN115850591A discloses a preparation method of an emulsion type binder and application of the emulsion type binder in a lithium ion battery cathode, the binder is designed in a core-shell structure, a core layer is prepared by pre-emulsifying and polymerizing vinyl aromatic monomers, alkyl acrylate monomers and the like, the glass transition temperature is higher, the structural stability of the lithium ion battery under the immersion condition of electrolyte is guaranteed, the shell layer contains the alkyl acrylate monomers, cyano monomers and the like, the glass transition temperature is lower, good binding force, slurry dispersibility and film forming property are provided, the core-shell pre-emulsion and initiator solution are synchronously dripped through stepwise pre-emulsifying, seed polymerizing and neutralizing and filtering during the preparation, the binder shell layer is rich in carboxyl groups, the emulsifier can participate in polymerization to reduce small molecule residues, the cross-linking density difference design of the core-shell layer gives consideration to mechanical strength and flexibility, the emulsion type binder is suitable for cathode active materials such as artificial graphite, silicon carbon and the like, the high-temperature performance, the cycle life and the low-temperature conductivity of the lithium battery can be improved, the emulsion type binder prepared by the method mainly relies on the difference of monomer composition to form, the core-shell layer lacks high-efficient interface chemical bridging, the electrolyte is immersed in the battery, the electrolyte long-time cycle condition of the electrolyte is easy to be immersed, the core-shell layer is easy to absorb the