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CN-122011977-A - Aqueous binder for lithium battery and preparation method thereof

CN122011977ACN 122011977 ACN122011977 ACN 122011977ACN-122011977-A

Abstract

The invention belongs to the technical field of lithium ion battery materials, and discloses a lithium battery water-based binder and a preparation method thereof. The adhesive is prepared by copolymerizing 20-40% of polar monomer, 59.5-79.5% of nonpolar monomer and 0.1-0.7% of crosslinking monomer, and the glass transition temperature of the adhesive is-9.2-58.8 ℃. The preparation method comprises the steps of (1) adding a polar monomer, a nonpolar monomer, a crosslinking monomer, an emulsifier and deionized water into a reaction container, stirring and mixing uniformly to obtain a mixed solution, and (2) heating the mixed solution to a reaction temperature of 50-90 ℃ after deoxidizing nitrogen, dropwise adding an initiator for reaction, cooling after the reaction is finished, and adding alkali liquor for neutralization until the pH value is 6-8 to obtain the product. The water-based adhesive can completely replace the traditional carboxymethyl cellulose and styrene-butadiene emulsion, and has the advantages of high cost efficiency, environmental friendliness and good adhesive property and electrical property.

Inventors

  • Pang Hongchuan
  • LI HONGMIAO
  • XIAO CHUANGHONG
  • HU XIANLEI

Assignees

  • 广州天赐高新材料股份有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. The lithium battery water-based adhesive is characterized by being obtained by copolymerizing 20% -40% of polar monomers, 59.5% -79.5% of nonpolar monomers and 0.1% -0.7% of crosslinking monomers in percentage by weight, and the glass transition temperature of the lithium battery water-based adhesive is-9.2-58.8 ℃.
  2. 2. The lithium battery water-based adhesive according to claim 1, wherein the lithium battery water-based adhesive is obtained by copolymerizing 20-30% of polar monomer, 69.5-79.5% of nonpolar monomer and 0.3-0.5% of crosslinking monomer in percentage by weight, and the glass transition temperature of the lithium battery water-based adhesive is-9.2-49.6 ℃.
  3. 3. The aqueous binder for lithium batteries according to claim 1, wherein the polar monomer is at least one of acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylonitrile, methacrylonitrile, 2-acetoxyacrylonitrile, 3-methoxyacrylonitrile, 3- (benzenesulfonyl) acrylonitrile, acrylamide, methacrylamide, methylolacrylamide, vinyl acetate, vinyl propionate, vinyl butyrate, N-vinylpyrrolidone, vinylpyridine, vinylimidazole, sodium p-styrenesulfonate, potassium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and allyl polyether.
  4. 4. The aqueous binder for lithium batteries according to claim 1, wherein the nonpolar monomer is at least one of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N-bis allyl dodecyl acrylate, octadecyl polyethylene glycol methacrylate, polyethylene glycol methoxyacrylate, vinyl methacrylate, alkoxyphenol acrylate, and isodecyl methacrylate.
  5. 5. The aqueous binder for lithium batteries according to claim 1, wherein the crosslinking monomer is at least one of divinylbenzene, diallyl phthalate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexamethylacrylate, divinyl glycol, diallyl itaconate, diallyl maleate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, ethoxylated bisphenol a dimethacrylate.
  6. 6. The aqueous binder for lithium batteries according to any one of claims 1 to 5, wherein the aqueous binder for lithium batteries has a weight average molecular weight of 10w to 50w.
  7. 7. The method for preparing the aqueous binder for the lithium battery as claimed in any one of claims 1 to 6, which is characterized by comprising the following preparation steps: (1) Adding a polar monomer, a nonpolar monomer, a crosslinking monomer, an emulsifier and deionized water into a reaction container, and uniformly stirring and mixing to obtain a mixed solution; (2) And heating the mixed solution to the reaction temperature of 50-90 ℃ after deoxidizing the nitrogen, dropwise adding an initiator to react, cooling to normal temperature after the reaction is completed, and adding alkali liquor to neutralize until the pH value is 6-8 to obtain the lithium battery water-based binder.
  8. 8. The method for preparing a lithium battery water-based binder according to claim 7, wherein the emulsifier is one or a mixture of more than one of an anionic emulsifier, a nonionic emulsifier and a reactive emulsifier, wherein the anionic emulsifier comprises at least one of higher alcohol sulfate, alkylbenzenesulfonate, alkyldiphenyloxide disulfonate, aliphatic sulfonate, aliphatic carboxylate and sulfate of a nonionic surfactant, the nonionic emulsifier comprises at least one of polyethylene glycol alkyl ester, alkylphenyl ether and alkyl ether, and the reactive emulsifier comprises at least one of sodium methallyl sulfonate, sodium allylsulfonate and sodium p-styrenesulfonate.
  9. 9. The method according to claim 7, wherein the initiator is a radical polymerization initiator, the radical polymerization initiator comprises at least one of a water-soluble polymerization initiator and a redox reaction polymerization initiator, the water-soluble polymerization initiator comprises at least one of potassium persulfate, sodium persulfate and ammonium persulfate, the redox reaction polymerization initiator comprises an oxidizing agent and a reducing agent, the oxidizing agent comprises at least one of potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, tert-butyl hydroperoxide, acetyl peroxide and dicumyl hydroperoxide, and the reducing agent comprises at least one of isoascorbic acid, ferrous ion salt, sodium sulfite and sodium bisulfite.
  10. 10. The preparation method of the lithium battery water-based adhesive, which is disclosed in claim 7, is characterized in that the reaction time is 0.5-6 h, and the alkali liquor is lithium hydroxide or sodium hydroxide solution.

Description

Aqueous binder for lithium battery and preparation method thereof Technical Field The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a lithium battery water-based binder and a preparation method thereof. Background As a battery with high performance and high energy density, a lithium battery has been widely used in the fields of electric vehicles, portable devices, energy storage systems, and the like. The preparation process of the anode material has an important influence on the battery performance. The current commonly used lithium battery cathode mainly comprises a cathode active material, a conductive additive, a binder, a current collector and the like, wherein the binder is an important component of the lithium battery cathode, the binder can tightly attach active substances and the conductive agent to the current collector to form a complete electrode, the active substances are prevented from falling off and stripping in the charging and discharging process, and meanwhile, the binder can uniformly disperse the active substances and the conductive agent, so that a good electron and ion transmission network is formed, high-efficiency transmission of electrons and lithium ions is realized, and the structural stability and electrochemical performance of the battery cathode are ensured. The conventional binder mainly uses carboxymethyl cellulose (CMC) and styrene-butadiene emulsion (SBR), however, there are some disadvantages in using CMC and SBR as a lithium battery anode binder, and the use process thereof is relatively complicated. Batch addition is required during battery manufacturing, which not only increases the number of manufacturing steps, but may also lead to uneven distribution of materials, affecting the overall performance of the battery. In addition, this batch addition may also result in reduced line efficiency and increased production costs. Secondly, CMC and SBR have limitations in their own performance as binders, and their binding performance is relatively low, which may cause the active material inside the battery to fall off during charge and discharge, affecting the cycle life and safety of the battery. In addition, both materials perform poorly in low temperature environments, which limits the application of lithium batteries in cold regions. The novel adhesive mainly comprises polyurethane, polyether, polyester, polyacrylate and the like, wherein the polyacrylate adhesive has good adhesive force and high temperature resistance and is widely applied. However, the glass transition temperature of the conventional polyacrylate binder is generally higher (above 60 ℃), the low-temperature discharge performance of the conventional polyacrylate binder needs to be further improved, and meanwhile, the conventional polyacrylate binder is low in flexibility and easy to crack in the process of high-speed coating and cell crimping in industrial production, so that the electrode performance and the production efficiency are affected. Disclosure of Invention Aiming at the defects of the existing lithium battery binder, the primary purpose of the invention is to provide a lithium battery water-based binder. The aqueous binder is a novel polyacrylic acid (PAA) lithium battery binder, can completely replace traditional carboxymethyl cellulose and styrene-butadiene emulsion, and can improve the binding performance and the low-temperature performance while simplifying the production process compared with the traditional carboxymethyl cellulose and styrene-butadiene emulsion. Through innovative chemical formula and process design, the novel adhesive can be added at one time, so that the production steps are reduced, and the production efficiency is improved. Meanwhile, the novel adhesive has higher bonding strength and better low-temperature stability, so that the overall performance and reliability of the lithium battery are improved. By the invention, the development of lithium battery technology is expected to be promoted, and the increasing energy storage requirement is met. Another object of the present invention is to provide a method for preparing the aqueous binder for lithium batteries. The invention aims at realizing the following technical scheme: A lithium battery water-based adhesive is obtained by copolymerizing 20-40% of polar monomer, 59.5-79.5% of nonpolar monomer and 0.1-0.7% of crosslinking monomer, wherein the glass transition temperature (Tg) of the lithium battery water-based adhesive is-9.2-58.8 ℃. Preferably, the lithium battery water-based adhesive is obtained by copolymerizing 20-30% of polar monomer, 69.5-79.5% of nonpolar monomer and 0.3-0.5% of crosslinking monomer in percentage by weight, and the glass transition temperature of the lithium battery water-based adhesive is-9.2-49.6 ℃. In the adhesive of the present invention, the polar monomer mainly provides the adhesive effect, the nonpolar monomer adjusts to lower t