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CN-121975462-A - Flexible polyethoxylated acrylic ester negative electrode binder and preparation method and application thereof

CN121975462ACN 121975462 ACN121975462 ACN 121975462ACN-121975462-A

Abstract

The invention relates to a flexible polyethoxylated acrylic acid ester negative electrode binder, a preparation method and application thereof, wherein the binder comprises the following components in percentage by weight of 30% -60% of flexible units and 40% -70% of rigid units. The flexible unit is ethoxylation acrylic ester monomer, and the rigid unit is one or more of acrylic acid and acrylamide. The adhesive can realize the characteristics of hardness and softness, not only ensures the adhesion, but also has certain flexibility, can effectively inhibit the volume expansion of silicon, and can increase the usage amount of silicon-based materials to more than 60 percent.

Inventors

  • SHAO JUNJIE
  • MA XIN
  • Bai Linming
  • CHEN GUOZHEN
  • ZHENG PING
  • LEI WENTAO
  • Fu Tianji
  • WANG SIYU

Assignees

  • 湖北航天化学技术研究所

Dates

Publication Date
20260505
Application Date
20260205

Claims (10)

  1. 1. A flexible polyethoxylated acrylic acid ester negative electrode binder is characterized by comprising, by weight, 30% -60% of flexible units and 40% -70% of rigid units.
  2. 2. The flexible polyethoxylated acrylic acid ester negative electrode binder according to claim 1, wherein the weight proportion of each component is 35% -50% of flexible units and 50% -65% of rigid units.
  3. 3. The flexible polyethoxylated acrylic acid ester negative electrode binder of claim 1 or 2, wherein the flexible unit is an ethoxylated acrylic acid ester monomer, and the ethoxylated acrylic acid ester monomer is one or more of an ethoxyethoxyethyl acrylic acid ester monomer, an ethoxylated lauryl alcohol acrylic acid ester monomer with different ethoxy substitution numbers and a polyethylene glycol diacrylate monomer; the rigid unit is one or more of acrylic monomer and acrylamide monomer.
  4. 4. A flexible polyethoxylated acrylic negative electrode binder according to claim 3 wherein the ethoxylated lauryl acrylate monomer has an ethoxy substitution number of 0-10.
  5. 5. The preparation method of the flexible polyethoxylated acrylic acid ester negative electrode binder is characterized by comprising the following steps of: Preparing alkali liquor, namely dissolving 11-22 parts by mass of sodium hydroxide into 220-440 parts by mass of water, and equally dividing into two parts for later use; preparing an initiator solution, namely dissolving 0.5-2 parts by mass of an initiator in 100-400 parts by mass of water to obtain an initiator aqueous solution; Step three, adding 20-40 parts by mass of acrylic acid monomer and 80-160 parts by mass of water into a reactor, introducing argon, dropwise adding half of alkali liquor in the step one under stirring for neutralization, then adding 30-60 parts by mass of ethoxylated acrylic ester monomer, 10-40 parts by mass of acrylamide monomer and 0.5-2 parts by mass of auxiliary agent, and heating to 50-80 ℃ under the argon atmosphere; step four, dropwise adding the initiator aqueous solution in the step two to polymerize for 1-10 h after the temperature is constant; And fifthly, cooling to room temperature, adding the other half of alkali liquor, stirring uniformly, pouring the mixture into 700-1100 parts by mass of water, and mixing uniformly to obtain the flexible polyethoxylated acrylic ester negative electrode binder.
  6. 6. The method for preparing the flexible polyethoxylated acrylic acid ester negative electrode binder of claim 5, wherein, The initiator is a water-soluble initiator, the water-soluble initiator is at least one of ammonium persulfate, potassium persulfate and sodium persulfate, and the use amount of the initiator is 0.5% -2% of the total weight of the flexible monomer and the rigid monomer; The auxiliary agent is at least one of a redox initiator and a chain transfer agent, and the dosage of the auxiliary agent accounts for 0.5% -2% of the total weight of the flexible monomer and the rigid monomer.
  7. 7. The preparation method of the flexible silicon-based negative electrode plate is characterized by comprising the following steps of: adding 250-500 parts by mass of sodium carboxymethyl cellulose aqueous solution into a stirring kettle, then adding 45-50 parts by mass of first conductive agent, and mixing to obtain conductive slurry; adding 300-400 parts by mass of silicon-based negative electrode and 0-100 parts by mass of graphite negative electrode into the conductive paste, and fully stirring to obtain silicon-based paste; adding 125-250 parts by mass of a second conductive agent into the silicon-based slurry, and fully stirring to obtain mixed slurry; Sequentially adding 658-783 parts by mass of the flexible polyethoxylated acrylic acid ester negative electrode binder in any one of claims 1-4 and 50-100 parts by mass of water into the mixed slurry, and fully stirring to obtain negative electrode slurry; and fifthly, sequentially coating the negative electrode slurry on the front and back sides of the current collector copper foil, and drying to obtain the flexible silicon-based negative electrode plate.
  8. 8. The method for preparing a flexible silicon-based negative electrode sheet according to claim 7, wherein the silicon-based material is a silicon-carbon material or a silicon-oxygen material; the graphite material is any one or more of artificial graphite, modified natural graphite, hard carbon and mesophase carbon microsphere materials.
  9. 9. The preparation method of the flexible silicon-based negative electrode piece according to claim 7, wherein the first conductive agent is conductive carbon black, and the second conductive agent is a carbon nano tube aqueous solution with the solid content of 0.4%; the solid content of the sodium carboxymethyl cellulose aqueous solution is 2.0+/-0.2%, and the solid content of the flexible polyethoxylated acrylic acid ester negative electrode binder is 6.0+/-0.5%.
  10. 10. A flexible lithium ion battery comprising a flexible negative electrode sheet prepared by the method of any one of claims 7-9.

Description

Flexible polyethoxylated acrylic ester negative electrode binder and preparation method and application thereof Technical Field The invention belongs to the technical field of lithium batteries, and particularly relates to a flexible polyethoxylated acrylic acid ester negative electrode binder, and a preparation method and application thereof. Background Flexible lithium batteries are an emerging energy storage technology with the core advantage of being flexible, foldable, and even stretchable. The method can break through the shape limitation of the traditional rigid battery and provide support for various innovative devices and application scenes. However, it still faces some challenges in terms of energy density, cycle life and cost. Silicon has a high theoretical lithium storage capacity (4200 mAh/g), making it a negative electrode material for high energy density flexible lithium batteries. As the silicon volume expands and contracts repeatedly, a series of adverse effects occur successively, resulting in damage to the electrode structure. At present, the binder of the silicon-based negative electrode is mainly polyacrylic acid, the glass transition temperature of the polyacrylic acid binder is high, when the content of silicon-based materials exceeds 60%, the pole piece is brittle, the processing performance is poor, and the polyacrylic acid cannot inhibit volume expansion in the circulating process, so that the battery has poor circulating performance. Therefore, there is a need to develop a binder that combines hardness and softness, while ensuring adhesion and flexibility, and while effectively inhibiting the volumetric expansion of silicon. Disclosure of Invention In view of the above, the invention aims to provide a flexible polyethoxylated acrylic acid ester negative electrode binder which is used for solving the problem of volume expansion after the content of silicon-based materials exceeds 60% and realizing stable long cycle of a lithium ion battery. The invention further aims at providing a preparation method of the flexible polyethoxylated acrylic acid ester negative electrode binder. The invention further aims at providing a preparation method of the flexible silicon-based negative electrode plate. Another object of the present invention is to provide a flexible lithium ion battery. In order to achieve the purpose, the technical scheme is that the flexible polyethoxylated acrylic acid ester negative electrode binder comprises, by weight, 30% -60% of flexible units and 40% -70% of rigid units. Further, the weight ratio of each component is as follows, 35% -50% of flexible units and 50% -65% of rigid units. Further, the flexible unit is an ethoxylated acrylic ester monomer, and the ethoxylated acrylic ester monomer is one or more of an ethoxyethoxy ethyl acrylic ester monomer, ethoxylated lauryl alcohol acrylic ester monomers with different ethoxysubstitution numbers and polyethylene glycol diacrylate monomers; the rigid unit is one or more of acrylic monomer and acrylamide monomer. Further, the number of ethoxy substitutions of the ethoxylated lauryl acrylate monomer is 0-10. A preparation method of a flexible polyethoxylated acrylic acid ester negative electrode binder comprises the following steps: Preparing alkali liquor, namely dissolving 11-22 parts by mass of sodium hydroxide into 220-440 parts by mass of water, and equally dividing into two parts for later use; preparing an initiator solution, namely dissolving 0.5-2 parts by mass of an initiator in 100-400 parts by mass of water to obtain an initiator aqueous solution; Step three, adding 20-40 parts by mass of acrylic acid monomer and 80-160 parts by mass of water into a reactor, introducing argon, dropwise adding half of alkali liquor in the step one under stirring for neutralization, then adding 30-60 parts by mass of ethoxylated acrylic ester monomer, 10-40 parts by mass of acrylamide monomer and 0.5-2 parts by mass of auxiliary agent, and heating to 50-80 ℃ under the argon atmosphere; step four, dropwise adding the initiator aqueous solution in the step two to polymerize for 1-10 h after the temperature is constant; And fifthly, cooling to room temperature, adding the other half of alkali liquor, stirring uniformly, pouring the mixture into 700-1100 parts by mass of water, and mixing uniformly to obtain the flexible polyethoxylated acrylic ester negative electrode binder. Further, the initiator is a water-soluble initiator, the water-soluble initiator is at least one of ammonium persulfate, potassium persulfate and sodium persulfate, and the use amount of the initiator is 0.5% -2% of the total weight of the flexible monomer and the rigid monomer; The auxiliary agent is at least one of a redox initiator and a chain transfer agent, and the dosage of the auxiliary agent accounts for 0.5% -2% of the total weight of the flexible monomer and the rigid monomer. A preparation method of a flexible silicon-based negative electrode plate