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CN-122025657-A - Carbon-coated aluminum foil process and preparation method thereof, and lithium ion battery

CN122025657ACN 122025657 ACN122025657 ACN 122025657ACN-122025657-A

Abstract

The invention relates to a carbon-coated aluminum foil process, a preparation method thereof and a lithium ion battery, which comprise an aluminum foil substrate, wherein a conductive composite layer which is coated and cured is arranged on the surface of the aluminum foil substrate, the conductive composite layer comprises, by weight, 5-7 parts of conductive carbon black, 3-5 parts of conductive graphite, 0.8-1.2 parts of functional auxiliary agent, 1.2-2.0 parts of dispersing agent and 40-50 parts of adhesive, and the thickness of the conductive composite layer is 0.4-1.8 mu m. The conductive network has high construction efficiency and strong overall conductivity, no toxic waste gas is discharged in the production process, no matched NMP recovery equipment is needed, and the production environmental protection cost and the safety risk are greatly reduced.

Inventors

  • CHEN GUANRONG
  • WENG BOMING

Assignees

  • 浙江博明环保节能科技有限公司

Dates

Publication Date
20260512
Application Date
20260226

Claims (9)

  1. 1. A carbon-coated aluminum foil process comprises an aluminum foil substrate and is characterized in that a conductive composite layer which is formed by coating and three-stage gradient drying and curing is arranged on the surface of the aluminum foil substrate, the thickness of the conductive composite layer is 0.4-1.8 mu m, the conductive composite layer comprises the following components, by weight, conductive carbon black, conductive graphite, a functional additive, a compound dispersing agent, and 40-60, 50-120, and 100-140.
  2. 2. The carbon-coated aluminum foil process of claim 1, wherein the conductive carbon black is acetylene black, the particle size is 21 nm-55 nm, the conductive graphite is reduced graphene oxide, and the thickness d of the sheet is less than or equal to 4.5nm.
  3. 3. The carbon-coated aluminum foil process of claim 1, wherein the binder is one of an acrylic resin, an aqueous styrene-acrylic emulsion, or a mixture thereof.
  4. 4. The carbon-coated aluminum foil process of claim 1, wherein the compound dispersant is composed of PVP and CMC-Li, wherein the weight ratio of PVP to CMC-Li is 1.6:1.
  5. 5. The method for preparing the carbon-coated aluminum foil according to any one of claims 1 to 4, comprising the following steps: step one, preparing carbon-coated slurry according to the component proportion; and step two, coating the carbon-coated slurry prepared in the step one on the surface of an aluminum foil substrate by adopting a micro-gravure, and carrying out three-stage gradient drying, curing and forming to obtain the carbon-coated aluminum foil with the conductive composite layer.
  6. 6. The method for preparing a carbon-coated aluminum foil according to claim 5, wherein the preparing the carbon-coated slurry in the first step sequentially comprises the following steps: S1, preparing a premix solvent, namely adding a dispersing agent PVP and deionized water into a dispersing kettle, and stirring at a high speed of 1200rpm for 5min until the PVP and the deionized water are completely dissolved to obtain the premix solvent; S2, conducting agent premixing and dispersing, namely uniformly mixing dispersant CMC-Li and 1/3 weight of conductive carbon black in a dry mode to obtain a mixture I, keeping high-speed stirring at 1500rpm of a dispersing kettle, scattering a small amount of the mixture I into a premixing solvent for many times, and continuing stirring for 15min after scattering is finished until the materials are completely dispersed; S3, conducting agent supplementary dispersion, namely adding the rest 2/3 weight of conductive carbon black and conductive graphite into a dispersion kettle, stirring at a low speed of 800rpm for 5min for preliminary uniform mixing, and then dispersing at a high speed of 1800rpm for 10min to obtain a mixture II; s4, conducting slurry sanding, namely transferring the mixture II into a sand mill, and performing sand milling treatment for 2-3 hours at 2500rpm, wherein the particle size D50 of the slurry is controlled to be less than or equal to 0.8 mu m; S5, conducting slurry stabilization and dispersion, namely cooling the sanded slurry to below 35 ℃, stirring at a low speed of 500rpm, slowly dripping a binder into the slurry, and continuing stirring for 20min to be uniform after dripping is finished to prevent the slurry from demulsification and gelation; S6, regulating the viscosity of the slurry, namely adding a functional additive into the slurry, stirring at a low speed of 500rpm for 10min until the functional additive is uniformly dispersed, and adding a small amount of deionized water to regulate the viscosity of the slurry at 25 ℃ to 2200 mPas-2800 mPas; s7, filtering and defoaming, namely filtering the regulated slurry through a 200-mesh filter screen, removing impurities and agglomerated particles, and standing and defoaming for 15 minutes after filtering to obtain the coatable carbon-coated slurry.
  7. 7. The method for preparing a carbon-coated aluminum foil as recited in claim 6, wherein the conductive carbon black in S2 is SP conductive carbon black, and the binder in S5 is aqueous acrylic resin.
  8. 8. The preparation method of the carbon-coated aluminum foil according to claim 6, wherein the functional auxiliary agent in the S6 is formed by mixing a rheological regulator, a coupling agent and an antifoaming agent, and the rheological regulator accounts for 10% -20%, the coupling agent accounts for 40% -50% and the antifoaming agent accounts for 30% -40% of the total weight of the functional auxiliary agent.
  9. 9. A lithium ion battery characterized in that a positive current collector of the battery is the carbon-coated aluminum foil of any one of claims 1 to 4, which is prepared by the method of any one of claims 5 to 8.

Description

Carbon-coated aluminum foil process and preparation method thereof, and lithium ion battery Technical Field The invention relates to the technical field of carbon-coated aluminum foils, in particular to a carbon-coated aluminum foil process and a preparation method thereof, and a lithium ion battery. Background With the deepening of application of lithium ion batteries in the field of new energy sources, carbon-coated aluminum foils are used as key materials of positive electrode current collectors, and the performance of the carbon-coated aluminum foils directly influences the energy density, the cycle life and the safety of the batteries. The aluminum foil is used as a current collector of the lithium ion battery, plays an important role in the battery, the surface of the aluminum foil carries active substances, electrons generated by the active substances of the positive electrode are converged to an external circuit to form current, and the functional coating is used for carrying out surface treatment on the current collector of the positive electrode of the battery, so that the adhesion between the active substances and the current collector and the capability of the positive electrode for collecting micro-current of the active substances can be improved, and the purpose of improving the multiplying power performance of the battery is achieved. One Chinese patent document with publication number of CN115621469A in the prior art discloses a carbon-coated layer slurry for improving conductivity and viscosity and a drying and forming process thereof, wherein 10 parts of graphene powder, 10 parts of carbon nano tubes, 10 parts of sodium carboxymethylcellulose and 200 parts of water are weighed according to parts by weight and added into a flask to be mixed to prepare a mixed slurry, wherein the particle size of the graphene powder is smaller than 120-150 mu m, the mixed slurry is placed into an ultrasonic disperser, ultrasonic treatment is carried out for 3 hours to obtain the conductive slurry, and 10 parts of polyvinylidene fluoride are dissolved in 100 parts of N-methylpyrrolidone to prepare the adhesive slurry. The carbon-coated aluminum foil is prepared by adopting single graphene as a conductive phase, and the graphene powder has good dispersibility, but single conductive agent is easy to agglomerate, the conductive network is low in construction efficiency, the overall conductive performance of the prepared carbon-coated aluminum foil is weak, a large amount of N-methylpyrrolidone (NMP) organic solvent is used in the carbon-coated slurry, the NMP is toxic and volatile, environmental protection and potential safety hazards exist in production, the solvent recovery process is complex, the cost is high, and the current lithium battery green manufacturing requirement is not met. Disclosure of Invention The invention aims to solve the technical problems of providing a carbon-coated aluminum foil process, a preparation method thereof and a lithium ion battery, wherein the conductive network has high construction efficiency, strong overall conductivity, no toxic exhaust emission in the production process, no need of matching NMP recovery equipment and great reduction of production environmental protection cost and safety risk. In order to solve the technical problems, the invention is realized by the following technical scheme: A carbon-coated aluminum foil process comprises an aluminum foil substrate, wherein a conductive composite layer which is formed by coating and three-stage gradient drying and curing is arranged on the surface of the aluminum foil substrate, the thickness of the conductive composite layer is 0.4-1.8 mu m, the conductive composite layer comprises the following components, by weight, conductive carbon black, conductive graphite, a functional auxiliary agent, a compound dispersing agent, an adhesive= (5-7), 0.8-1.2, 1.2-2.0 and 40-50, the three-stage gradient drying temperature is 40-60 ℃, 80-120 ℃, 50-70 ℃ and the curing temperature is 100-140 ℃. In one embodiment, the compound conductive phase is composed of conductive carbon black and conductive graphite, wherein the conductive carbon black is 5-7 parts by weight, and the conductive graphite is 3-5 parts by weight. For example, the conductive carbon black may be 5 parts, 6 parts, 7 parts, and the conductive graphite may be 3 parts, 4 parts, 5 parts, and specific point values between the above point values, and the present application is not intended to be exhaustive of the specific point values included in the range for brevity and conciseness. In one embodiment, the functional auxiliary agent is 0.8-1.2 parts by weight, for example, 0.8 part, 0.9 part, 1.0 part and 1.2 parts, and the functional auxiliary agent is formed by compounding a rheology regulator, a coupling agent and a defoaming agent, wherein the rheology regulator improves coating leveling property, the coupling agent enhances interface combination of a conductive phase