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CN-121975459-A - High-toughness binder for lithium battery and preparation method thereof

CN121975459ACN 121975459 ACN121975459 ACN 121975459ACN-121975459-A

Abstract

The invention relates to the field of binders, in particular to a high-toughness binder for a lithium battery and a preparation method thereof, which are used for solving the problems of poor toughness, insufficient compatibility and weak electrolyte resistance stability of the existing lithium battery binder; N-methyl pyrrolidone and acetone are added into a reaction kettle to be stirred, then core-shell microsphere dispersion liquid is dripped into the reaction kettle to be stirred, matrix polymer and elastic modifier are sequentially added to be stirred after the dripping is finished, then bis (trifluoromethanesulfonyl) imide lithium is added to be continuously stirred, polyethylene glycol diglycidyl ether is added to be stirred for reaction after the heating is finished, the reaction is naturally cooled to room temperature, and a screen mesh is used to obtain a high-toughness adhesive.

Inventors

  • LIU SHUAI
  • LI YIQIONG
  • LI CHENGEN

Assignees

  • 安徽豪能新材料科技有限公司

Dates

Publication Date
20260505
Application Date
20260227

Claims (9)

  1. 1. The high-toughness adhesive for the lithium battery is characterized by comprising the following components in parts by weight: 1300-1900 parts of N-methylpyrrolidone, 433-633 parts of acetone, 83-88 parts of core-shell microsphere dispersion liquid, 35-50 parts of matrix polymer, 25-40 parts of elastic modifier, 3-8 parts of lithium bis (trifluoromethanesulfonyl) imide and 10-20 parts of polyethylene glycol diglycidyl ether; Wherein, the elastic modifier is prepared by the following steps: step a1, mixing absolute ethyl alcohol and 12-hydroxystearic acid, stirring for reaction, adding nano titanium dioxide for continuous stirring, adding gamma-aminopropyl triethoxysilane for continuous stirring, adding deionized water for continuous stirring for reaction, adjusting pH, stirring for reaction, cooling, vacuum filtration, washing, vacuum filtration, vacuum drying, grinding and sieving to obtain hybrid powder; step a2, mixing deionized water and the hybrid powder, stirring for reaction, then performing ultrasonic dispersion to obtain hybrid powder dispersion liquid, adding emulsion polymerized styrene-butadiene rubber into the hybrid powder dispersion liquid for continuous stirring, adding polyquaternary ammonium salt for stirring, standing, adding natural latex for stirring, performing vacuum filtration, washing, then performing vacuum drying and grinding to obtain master batch; Step a3, adding master batch into an internal mixer, sequentially adding zinc oxide, N-isopropyl-N '-phenyl paraphenylenediamine and stearic acid, continuously banburying, cooling, then adding into an open mill, stabilizing for 5min after the complete roll wrapping of the sizing material, sequentially adding elemental sulfur, N-cyclohexyl-2-benzothiazole sulfenamide and 2,2' -dibenzothiazyl disulfide, mixing, cooling, standing, vulcanizing, and cooling to obtain a composite material blank; and a4, adding the composite material blank into absolute ethyl alcohol, grinding, and then drying in vacuum to obtain the elastic modifier.
  2. 2. The high-toughness binder for lithium batteries according to claim 1, wherein the dosage ratio of the absolute ethyl alcohol, the 12-hydroxystearic acid, the nano titanium dioxide, the gamma-aminopropyl triethoxysilane and the deionized water in the step a1 is 300-420mL, 2.70-3.78g, 22.0-30.8g, 5-7g, 100-140mL, and the dosage ratio of the deionized water, the hybrid powder, the emulsion styrene-butadiene rubber, the polyquaternium and the natural latex in the step a2 is 200-250mL, 20-25g, 250-312g, 8-10g, 60-75g.
  3. 3. The high-toughness binder for lithium batteries according to claim 1, wherein the nano-titania in step a1 has a particle size of 50-100nm.
  4. 4. The high-toughness adhesive for lithium batteries according to claim 1, wherein the dosage ratio of the masterbatch, zinc oxide, N-isopropyl-N '-phenyl-p-phenylenediamine, stearic acid, elemental sulfur, N-cyclohexyl-2-benzothiazole sulfenamide and 2,2' -dibenzothiazyl disulfide in the step a3 is 100.0-116.6g:5.00-5.83g:1.50-1.75g:2.0-2.3g:1.8-2.1g:1.2-1.4g:0.80-0.93g, and the dosage ratio of the composite blank and absolute ethyl alcohol in the step a4 is 100-110g:300-330mL.
  5. 5. The high-toughness binder for lithium batteries according to claim 1, wherein said core-shell microsphere dispersion is prepared by the steps of: step b1, adding nano titanium dioxide into absolute ethyl alcohol, performing ultrasonic dispersion and grinding to obtain pretreated titanium dioxide; Step b2, mixing N, N-dimethylformamide and absolute ethyl alcohol, adding polyethylene glycol, stirring, adding pretreated titanium dioxide, stirring, starting an ultrasonic dispersing instrument, carrying out ultrasonic stirring for cooperative treatment, adding polyvinylidene fluoride, continuously stirring, regulating pH, continuously stirring for reaction, cooling, centrifuging, washing precipitate, drying, grinding and sieving to obtain titanium dioxide core-polyvinylidene fluoride shell core-shell microspheres; And b3, adding N-methyl pyrrolidone and acetone into a beaker, stirring, adding titanium dioxide core-polyvinylidene fluoride shell core-shell microspheres, stirring, performing ultrasonic dispersion, and continuing stirring to obtain a core-shell microsphere dispersion liquid.
  6. 6. The high-toughness binder for lithium batteries according to claim 5, wherein the dosage ratio of nano titanium dioxide to absolute ethyl alcohol in the step b1 is 8-10g:50.0-62.5mL, the dosage ratio of N, N-dimethylformamide, absolute ethyl alcohol, polyethylene glycol, pretreated titanium dioxide and polyvinylidene fluoride in the step b2 is 100-200mL:50-100mL:0.5-1.0g:8-10g:2-4g, and the dosage ratio of N-methylpyrrolidone, acetone and titanium dioxide core-polyvinylidene fluoride shell core-shell microspheres in the step b3 is 37.5-43.5mL:12.5-14.5mL:35-46g.
  7. 7. The high-toughness binder for lithium batteries according to claim 5, wherein the nano-titania in step b1 has a particle size of 30-60nm.
  8. 8. A method for preparing the high-toughness binder for lithium batteries, which is used for preparing the high-toughness binder for lithium batteries according to any one of claims 1 to 7, comprising the following steps: Weighing 1300-1900 parts of N-methylpyrrolidone, 433-633 parts of acetone, 83-88 parts of core-shell microsphere dispersion liquid, 35-50 parts of matrix polymer, 25-40 parts of elastic modifier, 3-8 parts of lithium bis (trifluoromethanesulfonyl) imide and 10-20 parts of polyethylene glycol diglycidyl ether according to parts by weight for later use; Adding N-methyl pyrrolidone and acetone into a reaction kettle, stirring, dripping core-shell microsphere dispersion liquid into the reaction kettle, stirring, adding a matrix polymer, stirring, adding an elastic modifier, stirring, adding lithium bistrifluoromethane sulfonyl imide, continuously stirring, heating, adding polyethylene glycol diglycidyl ether, stirring for reaction, cooling, and sieving to obtain the high-toughness adhesive.
  9. 9. The method for preparing the high-toughness binder for the lithium battery, according to claim 8, wherein the matrix polymer in the second step is formed by mixing polyvinylidene fluoride and polyacrylic acid according to the dosage ratio of 2g to 1 g.

Description

High-toughness binder for lithium battery and preparation method thereof Technical Field The invention relates to the field of binders, in particular to a high-toughness binder for a lithium battery and a preparation method thereof. Background The lithium battery has high energy density, long cycle life and environmental protection, and is widely applied to the fields of new energy automobiles, portable electronic equipment, energy storage systems and the like. The binder is a key component of the lithium battery pole piece, and has the core function of firmly binding the active substance, the conductive agent and the current collector to form a stable pole piece structure, and meanwhile, the volume expansion of the pole piece in the charge-discharge cycle is required to be adapted, so that cracking and powder removal are prevented, and the long-acting cycle stability of the battery is ensured. The main current binder of the negative electrode of the current lithium battery is polyvinylidene fluoride, and although the chemical stability and electrolyte resistance are good, the main current binder is strong in rigidity and poor in toughness, and is difficult to buffer the volume expansion of the graphite negative electrode when lithium is intercalated, so that the binder is easy to crack and the pole piece is easy to break, the capacity of the battery is fast attenuated, and the cycle life is shortened. In addition, the existing modified adhesive is poor in electrolyte resistance stability, and is easy to expand and degrade after being soaked for a long time, so that the failure of the pole piece is aggravated. Therefore, the development of the adhesive which has high toughness, high bonding strength and excellent electrolyte stability and is suitable for the cyclic volume change of the pole piece is important to the improvement of the performance of the lithium battery. Disclosure of Invention In order to overcome the technical problems, the invention aims to provide a high-toughness adhesive for a lithium battery and a preparation method thereof. The aim of the invention can be achieved by the following technical scheme: in a first aspect, the application provides a high-toughness binder for a lithium battery, which comprises the following components in parts by weight: 1300-1900 parts of N-methylpyrrolidone, 433-633 parts of acetone, 83-88 parts of core-shell microsphere dispersion liquid, 35-50 parts of matrix polymer, 25-40 parts of elastic modifier, 3-8 parts of lithium bis (trifluoromethanesulfonyl) imide and 10-20 parts of polyethylene glycol diglycidyl ether; Wherein, the elastic modifier is prepared by the following steps: adding absolute ethyl alcohol and 12-hydroxystearic acid into a three-neck flask provided with a stirrer, a thermometer, an air duct and a constant pressure dropping funnel, introducing nitrogen for protection, stirring and reacting for 40-50min under the conditions of the temperature of 45-50 ℃ and the stirring speed of 280-300r/min, adding nano titanium dioxide, continuing stirring for 20-22min, adding gamma-aminopropyl triethoxysilane, continuing stirring for 15-17min, adding deionized water dropwise while stirring, controlling the dropping speed to be 1-2 drops/s, continuing stirring and reacting for 10-12min after the dropwise adding, then gradually adjusting the pH value to be 10 by ammonia water, transferring the three-neck flask into a magnetic water bath stirring pot, stirring and reacting for 6h under the conditions of the temperature of 55-60 ℃ and the stirring speed of 750-800r/min, naturally cooling the reaction to room temperature after the reaction, vacuum suction filtering, washing the filter cake by ethanol solution for 3 times, transferring the filter cake to a vacuum drying box, drying for 3h under the conditions of the temperature of 75-80 ℃ and the vacuum degree of-0.09 MPa, taking out the filter cake for 3h under the conditions of the vacuum filtering speed of 3 r/min, and granulating for 3h by a ball mill, and grinding the ball mill at the speed of 300r/min to obtain a ball mill, wherein the mixed powder is obtained after the ball mill speed is subjected to the ball grinding for 1-grinding; Adding deionized water and hybrid powder into a beaker, stirring and reacting for 30-35min under the condition of stirring speed of 480-500r/min, then ultrasonically dispersing for 15-17min under the condition of power of 280-300W to obtain hybrid powder dispersion, maintaining the stirring speed of 480-500r/min, adding emulsion polymerized styrene-butadiene rubber into the hybrid powder dispersion liquid, dropwise adding 1-2 drops/s, continuously stirring for 60-70min after dropwise adding, reducing the stirring speed to 280-300r/min, adding polyquaternium, stirring for 30-32min, stopping stirring and standing for layering for 20min, adding natural latex, stirring for 40-42min under the condition of stirring speed of 180-200r/min, vacuum suction filtering, washing a fil