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CN-122011976-A - Adhesive, and preparation method and application thereof

CN122011976ACN 122011976 ACN122011976 ACN 122011976ACN-122011976-A

Abstract

The application relates to a binder, a preparation method and application thereof, wherein the binder comprises 69.5-79.5% of polyacrylic acid matrix, 10-15% of conductive polymer, 5-15% of functional nanoparticle and 0.3-1% of crosslinking agent, wherein the functional nanoparticle is nanoparticle with amino-modified surface. According to the scheme provided by the application, the adhesive has excellent conductivity, high-pressure oxidation resistance and compatibility with residual lithium on the surface of the high-nickel positive electrode, so that the interface binding force with the high-nickel positive electrode active material can be improved, the contact resistance of the positive electrode interface can be reduced, and the battery can have excellent cycle performance and multiplying power performance.

Inventors

  • JIANG BING
  • LIU GUANXIN
  • LIAO XINGQUN

Assignees

  • 深圳市豪鹏科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260316

Claims (10)

  1. 1. A binder, which is characterized by comprising a polyacrylic acid matrix, a conductive polymer, functional nano particles and a crosslinking agent; The mass fraction of the polyacrylic acid matrix in the binder is 69.5% -79.5%, the mass fraction of the conductive polymer in the binder is 10% -15%, the mass fraction of the functional nano particles in the binder is 5% -15%, and the mass fraction of the crosslinking agent in the binder is 0.3% -1%; wherein the functional nano particles are nano particles with amino modified surfaces.
  2. 2. The adhesive of claim 1, wherein the polyacrylic acid matrix has a structural formula shown in formula 1: 1 (1) Wherein, n is m= (8.5:1.5) - (9.5:0.5); and/or the polyacrylic acid matrix has a molecular weight of 5X 10 4 g/mol~8×10 4 g/mol; and/or the hydroxyl content in the polyacrylic acid matrix is 1.2 mmol/g-1.5 mmol/g.
  3. 3. The binder of claim 1 wherein the conductive polymer comprises at least one of poly (3, 4-ethylenedioxythiophene) -poly (sodium styrenesulfonate), polyethylene glycol modified poly (3, 4-ethylenedioxythiophene), poly (3, 4-ethylenedioxythiophene) -poly (sodium styrenesulfonate), carboxyl functionalized poly (3, 4-ethylenedioxythiophene); And/or the conductivity of the conductive polymer aqueous solution with the mass fraction of 1.0-1.5 wt% is not less than 100S/m.
  4. 4. The binder of claim 1 wherein the functional nanoparticle comprises at least one of ceria having an amino modification on a surface, alumina having an amino modification on a surface, titania having an amino modification on a surface, zirconia having an amino modification on a surface, and ferroferric oxide having an amino modification on a surface; and/or the particle size of the functional nano particles is 20 nm-50 nm; And/or the amino content in the functional nano particles is 0.8 mmol/g-1.2 mmol/g; And/or the electrochemical stability window of the functional nanoparticle is not less than 4.8V; And/or the cross-linking agent comprises at least one of adipic acid dihydrazide, polyethylene glycol dihydrazide and succinic acid dihydrazide.
  5. 5. A method of preparing the adhesive according to any one of claims 1 to 4, comprising the steps of: Mixing the polyacrylic acid matrix, the conductive polymer, the functional nano particles and the cross-linking agent in a water solvent according to the corresponding mass fraction to obtain the binder; The mixing temperature of the mixing treatment is 50-70 ℃ and the mixing time is 1-3 h.
  6. 6. The method of preparing a binder of claim 5 wherein the polyacrylic acid matrix is prepared by: adding an initiator into an aqueous solution containing acrylic acid and 2-hydroxyethyl acrylate, and performing polymerization treatment to obtain the polyacrylic acid matrix; Preferably, the initiator comprises at least one of ammonium persulfate, sodium persulfate and potassium persulfate; Preferably, the mass fraction of the initiator in the aqueous solution comprising the acrylic acid and the 2-hydroxyethyl acrylate is 0.1% -0.8%; Preferably, the reaction temperature of the polymerization reaction is 60-70 ℃ and the reaction time is 1-5 h.
  7. 7. A positive electrode sheet comprising a positive electrode current collector and a positive electrode coating layer supported on at least one side of the positive electrode current collector, the positive electrode coating layer comprising the binder according to any one of claims 1 to 4 or the binder produced by the binder production method according to any one of claims 5 to 6.
  8. 8. The positive plate according to claim 7, wherein the positive coating comprises a positive active material, a conductive agent and a binder, and the mass ratio of the positive active material to the conductive agent to the binder is (90-94): 3-5): 2-4; Preferably, the chemical formula of the positive electrode active material is LiNi x Co y Mn 1-x-y O 2 , and x is more than or equal to 0.8.
  9. 9. The positive electrode sheet according to claim 7, wherein the peel strength of the positive electrode coating layer from the positive electrode current collector is not lower than 2N/m; and/or the interface contact resistance between the positive electrode coating and the positive electrode current collector is not higher than 30mΩ cm 2 ; And/or, the positive electrode slurry used for preparing the positive electrode coating layer has a viscosity change rate of less than 5% after being stored for 72 hours by standing.
  10. 10. A battery comprising the positive electrode sheet according to any one of claims 7 to 9.

Description

Adhesive, and preparation method and application thereof Technical Field The application relates to the technical field of batteries, in particular to a binder, a preparation method and application thereof. Background The lithium ion battery is widely applied to the fields of 3C digital codes, electric tools, aerospace, energy storage, power automobiles and the like due to the advantages of high specific energy, no memory effect, long cycle life and the like, and the rapid development of electronic information technology and consumer products puts forward higher requirements on the electrochemical performance of the lithium ion battery. The positive electrode sheet is prepared by coating a positive electrode slurry containing a binder on a positive electrode current collector, wherein the binder is critical to maintaining the stability of the coating. The traditional fluorine-based binder (such as PVDF) not only faces serious environmental protection and energy consumption challenges due to dependence on toxic N-methyl pyrrolidone (NMP) solvent and a high-temperature drying process, but also has the inherent defects of weak interfacial bonding force with a high-nickel positive electrode (such as NCM 811), poor high-pressure oxidation resistance, rapid increase of cyclic resistance and the like, and is extremely easy to cause stripping of electrode active materials and aggravation of side reactions, and the electrode active materials and the high-nickel surface residual lithium are easy to cause dehydrofluorination reaction to cause advanced gelation of positive electrode slurry, so that coating uniformity and coating integrity are damaged, and the long-cycle and high-rate performance of a battery are obviously deteriorated due to the synergistic effect of multiple failure mechanisms, so that the binder becomes a key bottleneck for limiting breakthrough of next-generation high-energy lithium electric technology. Therefore, development of a novel binder is needed to synergistically improve the cycle performance and rate performance of the nickel-rich battery. Disclosure of Invention In order to solve or partially solve the problems in the related art, the application provides a binder, a preparation method and application thereof, wherein the binder has excellent conductivity, high-pressure oxidation resistance and compatibility with residual lithium on the surface of a high-nickel positive electrode, can improve the interfacial binding force with a high-nickel positive electrode active material, and reduces the contact resistance of the positive electrode interface, so that the battery has excellent cycle performance and rate performance. The first aspect of the application provides a binder, wherein the binder comprises a polyacrylic acid matrix, a conductive polymer, functional nano particles and a crosslinking agent; The mass fraction of the polyacrylic acid matrix in the binder is 69.5% -79.5%, the mass fraction of the conductive polymer in the binder is 10% -15%, the mass fraction of the functional nano particles in the binder is 5% -15%, and the mass fraction of the crosslinking agent in the binder is 0.3% -1%; wherein the functional nano particles are nano particles with amino modified surfaces. The adhesive of the first aspect, wherein the polyacrylic acid matrix has a structural formula shown in formula 1: 1 (1) Wherein, n is m= (8.5:1.5) - (9.5:0.5); and/or the polyacrylic acid matrix has a molecular weight of 5X 10 4g/mol~8×104 g/mol; and/or the hydroxyl content in the polyacrylic acid matrix is 1.2 mmol/g-1.5 mmol/g. The binder of the first aspect, wherein the conductive polymer comprises at least one of poly (3, 4-ethylenedioxythiophene) -poly (sodium styrenesulfonate), polyethylene glycol modified poly (3, 4-ethylenedioxythiophene), poly (3, 4-ethylenedioxythiophene) -poly (sodium styrenesulfonate), carboxyl functionalized poly (3, 4-ethylenedioxythiophene); And/or the conductivity of the conductive polymer aqueous solution with the mass fraction of 1.0-1.5 wt% is not less than 100S/m. The binder of the first aspect, wherein the functional nanoparticle comprises at least one of ceria with amino modification on a surface, alumina with amino modification on a surface, titania with amino modification on a surface, zirconia with amino modification on a surface, and ferroferric oxide with amino modification on a surface; and/or the particle size of the functional nano particles is 20 nm-50 nm; And/or the amino content in the functional nano particles is 0.8 mmol/g-1.2 mmol/g; And/or the electrochemical stability window of the functional nanoparticle is not less than 4.8V; And/or the cross-linking agent comprises at least one of adipic acid dihydrazide, polyethylene glycol dihydrazide and succinic acid dihydrazide. A second aspect of the present application provides a method for preparing the binder according to the first aspect, comprising the steps of: Mixing the polyacrylic acid matrix, the conduc