An aluminum foil coating material and its preparation method

Abstract

This invention provides an aluminum foil coating material and its preparation method, relating to the field of aluminum foil technology. The aluminum foil coating material comprises the following raw materials in parts by weight: 3-8 parts activated carbon, 5-12 parts graphene, 10-20 parts water-based conductive resin, 1-5 parts polyaniline, 1-5 parts eucommia gum, 1-5 parts N-methylpyrrolidone, 0.5-1.5 parts coupling agent, 0.1-1 parts adhesive, and 30-50 parts solvent. The aluminum foil coating material exhibits strong adhesion, high conductivity, and good corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of aluminum foil technology, and more specifically, to an aluminum foil coating material and its preparation method. Background Technology

[0002] Current collectors play a crucial role in battery design, serving to support the active material layer and connect internal and external circuits. Their geometry and surface properties affect the rate of electron transfer. The interfacial characteristics between the current collector and the active material layer significantly impact battery capacity, rate performance, and cycle life. According to the requirements of lithium-ion battery manufacturing processes, current collectors should possess high conductivity, chemical inertness in the electrolyte, sufficient mechanical strength, thinness, and good contact with the electrode material layers.

[0003] When aluminum foil is used as the positive electrode current collector, it is susceptible to localized anodic corrosion during charging and discharging. This increases the interfacial contact resistance between the electrode material layer and the current collector, weakens the bonding strength between them, and consequently increases the battery's internal resistance, ultimately leading to performance degradation in lithium-ion batteries. To prevent corrosion of the aluminum foil current collector and enhance the adhesion between the aluminum foil and the electrode material layer, surface modification of the aluminum foil can be performed. Currently, this is mainly achieved by coating the aluminum foil surface with a conductive carbon layer. This increases the contact area between the current collector and the active material, reducing polarization, and also prevents direct contact between the current collector and the electrolyte, thus reducing corrosion. However, the use of grease during aluminum foil production for demolding and the easy oxidation of the aluminum foil by oxygen during storage to form a dense oxide film affect its adhesion to the conductive carbon layer and its own electrical properties. Summary of the Invention

[0004] The purpose of this invention is to provide an aluminum foil coating material with strong adhesion, high conductivity, and good corrosion resistance.

[0005] Another objective of this invention is to provide a method for preparing an aluminum foil coating material, which can improve the conductivity and corrosion resistance of the aluminum foil and enhance its adhesion to the positive electrode material of the battery.

[0006] The embodiments of the present invention are achieved through the following technical solutions:

[0007] An aluminum foil coating material comprises the following raw materials in parts by weight: 3-8 parts activated carbon, 5-12 parts graphene, 10-20 parts water-based conductive resin, 1-5 parts polyaniline, 1-5 parts eucommia gum, 1-5 parts N-methylpyrrolidone, 0.5-1.5 parts coupling agent, 0.1-1 parts adhesive, and 30-50 parts solvent.

[0008] A method for preparing an aluminum foil coating material includes the following steps:

[0009] S1. Mix graphene and solvent, stir ultrasonically, add activated carbon, and continue stirring to obtain the first slurry;

[0010] S2. Mix water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir to obtain the second slurry;

[0011] S3. Add the first slurry to the second slurry, ultrasonically stir, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

[0012] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0013] In this invention, activated carbon particles possess abundant pore structures and a large specific surface area; activated carbon microspheres have a high specific surface area and a unique spherical lamellar structure; and activated carbon fibers possess a unique pore structure, abundant surface functional groups, high specific surface utilization, a disordered graphite structure, and a hierarchical pore distribution structure. Graphene possesses a very high specific surface area, high specific capacity, excellent mechanical properties, excellent electrical and thermal conductivity, and stable physicochemical properties. Through the encapsulation / coating of activated carbon microspheres and graphene on the surface of activated carbon particles, and the electrical connections between different particles formed by activated carbon fibers, a three-dimensional conductive network can be constructed. Through the effective synergistic effect of multiple carbon materials, the conductivity, pore structure, and pore size distribution of the material are all improved.

[0014] Waterborne conductive resins possess excellent corrosion resistance, film-forming properties, and adhesion. Polyaniline contains a large number of conjugated π-electron systems, providing charge carriers such as holes or electrons, ensuring the conductivity of the coated material layer. Eucommia ulmoides gum exhibits good acid and alkali resistance and hydrophobicity. Coupling agents can act as crosslinking agents and also enhance the density of the coating material. Waterborne conductive resins, polyaniline, and eucommia ulmoides gum, under the action of coupling agents and N-methylpyrrolidone, can crosslink or coalesce to form a blended composite system. The waterborne conductive resin improves the material's adhesion and corrosion resistance, the polyaniline improves the material's conductivity, and the eucommia ulmoides gum improves the material's acid and alkali resistance and hydrophobicity. The coupling agent also increases the density of the coating, thereby significantly improving the material's performance.

[0015] The first slurry is added to the second slurry to encapsulate / coat the first slurry, forming a composite structure. This prevents the agglomeration and precipitation between graphene and activated carbon. At the same time, polyaniline and water-based conductive resin can graft and modify the graphene, generating a larger electric double layer on the graphene surface, improving the conductivity of graphene, and enhancing the adhesion of graphene and activated carbon to aluminum foil. Then, an adhesive is added to improve the interaction force between the second slurry and the first slurry, making the three-dimensional conductive network constructed by graphene and activated carbon more stable, improving the conductivity of aluminum foil, and enhancing its adhesion to the battery cathode material. Detailed Implementation

[0016] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0017] An aluminum foil coating material comprises the following raw materials in parts by weight: 3-8 parts activated carbon, 5-12 parts graphene, 10-20 parts water-based conductive resin, 1-5 parts polyaniline, 1-5 parts eucommia gum, 1-5 parts N-methylpyrrolidone, 0.5-1.5 parts coupling agent, 0.1-1 parts adhesive, and 30-50 parts solvent.

[0018] Activated carbon comprises activated carbon particles, activated carbon microspheres, and activated carbon fibers, with a weight ratio of 2:1:1. Activated carbon particles are black, porous solid carbonaceous materials produced by carbonizing and activating bio-derived organic matter. During activation, their microcrystalline structure, with its orderly arrangement, generates carbon defects, forming abundant pores and a large specific surface area. Activated carbon microspheres are spherical activated carbon materials with a high specific surface area. Interphase carbon microspheres not only possess the general properties of carbon materials but also exhibit unique morphological characteristics such as a spherical lamellar structure. Activated carbon fibers are made from phenolic fibers through carbonization and activation, exhibiting high carbonization yield, large pore size, good conductivity, and high mechanical strength. Activated carbon fibers possess a unique pore structure, abundant surface functional groups, low density, and can generate a high specific capacity. They also possess a disordered graphite structure and a hierarchical pore distribution structure, which is beneficial for sufficient electrolyte wetting and effective charge adsorption. Furthermore, they have a high specific surface utilization rate, forming a conductive network and improving electrode conductivity. At this ratio, activated carbon particles can be fully embedded into the spherical lamellar structure of activated carbon microspheres, enhancing the encapsulation effect of the microspheres on the activated carbon particles. This allows the microspheres to regulate the pore structure and pore size distribution of the activated carbon particles, improving the porosity utilization rate and effectively converting the high specific surface area of ​​the activated carbon particles into high energy storage density, thus enhancing the conductivity of the activated carbon particles. Simultaneously, activated carbon fibers enable electrical connections between the activated carbon particles encapsulated by the microspheres and between the microspheres themselves, thereby constructing a three-dimensional conductive network between the activated carbon fibers, activated carbon particles, and activated carbon microspheres. The rich surface functional groups and low density of the activated carbon fibers enhance the specific capacity of the three-dimensional conductive network. Through the effective synergistic effect of the multi-element carbon materials, the conductivity, pore structure, and pore size distribution of the material are all improved.

[0019] Graphene possesses a very high specific surface area, high specific capacity, excellent mechanical properties, excellent electrical and thermal conductivity, and stable physicochemical properties. By using graphene in combination with activated carbon, the edge activity of graphene can be reduced, the aggregation / stacking of graphene can be decreased, and the actual specific surface area of ​​graphene can be increased.

[0020] Waterborne conductive resins include waterborne acrylic resin, waterborne polyurethane dispersion, and waterborne epoxy resin, with a weight ratio of 2:1:3. Waterborne acrylic resin exhibits good flexibility, leveling properties, and adaptability, improving coating adhesion and forming a dense protective film on the aluminum foil surface. It also possesses excellent hydrophilicity and corrosion resistance, effectively protecting the aluminum foil from environmental erosion and extending its service life. The main function of the waterborne polyurethane dispersion is to better bridge the aqueous / oil phases, adjust the system's viscosity and rheological properties, and lower the minimum film-forming temperature, exhibiting excellent film-forming and mechanical properties. Waterborne epoxy resin possesses excellent anti-corrosion properties, forming a robust protective film with the aluminum foil, effectively resisting the erosion of various chemicals and protecting the aluminum foil from corrosion.

[0021] By improving the rheological properties of the material and lowering the Tg of the dispersion through waterborne polyurethane dispersion, waterborne acrylic resin, waterborne epoxy resin and waterborne polyurethane dispersion can have enough time to aggregate with each other, forming a coating film with interpenetrating molecular chain segments, thus giving the coating better sealing performance.

[0022] Polyaniline, with its backbone containing alternating benzene rings and nitrogen atoms, is a unique conductive polymer exhibiting excellent electrochemical activity and environmental stability. As a conjugated conductive polymer, polyaniline's π electrons, while possessing delocalization capabilities, are not free electrons. The conjugated structure in the molecule increases the π electron system, enhancing electron delocalization and expanding their mobility. When the conjugated structure reaches a sufficiently large size, the compound can donate free electrons, thus enabling conductivity. Polyaniline possesses high electrical conductivity, is environmentally friendly, and has a unique doping mechanism. It can be crosslinked with aqueous conductive resins to form composite structures.

[0023] Eucommia gum is a natural polymer material with excellent properties of both rubber and plastic, and it has good resistance to acids and alkalis and hydrophobicity.

[0024] Furthermore, the coupling agent includes titanate coupling agents and silane coupling agents, with a weight ratio of 1:2-4. The silane coupling agent includes one or more of KH550, KH560, KH570, KH580, KH590, KH602, and KH792. The hydroxyl groups generated after hydrolysis of the silane coupling agent can combine with hydroxyl groups on the metal surface, forming a protective coating with good corrosion resistance. Titanate coupling agents have the characteristic of connecting organic and inorganic phases and are often used as molecular bridges, connecting one end to the organic phase and the other end to the inorganic phase. They also possess a large spatial molecular structure. When silane coupling agents and titanate coupling agents are used in combination, the sealing layer can change from a single silane small molecule structure to a state where titanate large molecule structures and silane small molecule structures coexist, effectively increasing the density of the sealing layer and thus increasing its corrosion resistance. Titanate coupling agents can also be linked to graphene / activated carbon at one end and eucommia gum at the other end to form an inorganic-organic composite system with a macromolecular structure, which improves the dispersion of graphene in the material and makes the material easier to bond with the aluminum foil surface, thereby enhancing the bonding strength between the material and the aluminum foil.

[0025] Furthermore, the adhesive includes one or more of polyvinylidene fluoride (PVDF), polyacrylic acid, and polyvinyl alcohol (PVA). PVDF can improve the adhesion of materials to the aluminum foil, preventing the active material from detaching or agglomerating during charge-discharge cycles, maintaining electrode structural stability, and improving the overall performance of the battery. It also promotes the wettability of the electrolyte within the electrode, facilitating lithium-ion transport between active materials and improving the battery's rate performance and cycle life. Polyacrylic acid, as a water-soluble polymer, has excellent bonding properties, reducing the contact resistance between the positive and negative electrode materials and the current collector, improving their adhesion. It can form strong interactions with the active material and the aluminum foil, helping to form a stable solid electrolyte interface, thereby improving the battery's cycle stability. The hydrogen bonds in the PVA molecule can interact with the hydroxyl groups in the alumina film on the aluminum foil surface, forming strong chemical bonds, thus forming a thin film on the aluminum foil surface that is difficult to separate, improving the coating's wear resistance, high-temperature resistance, and corrosion resistance. In addition, PVA can enhance the barrier properties of the aluminum foil against gases and water vapor. The combination of these factors can improve the adhesion between the coating material and the aluminum foil, as well as the adhesion between the aluminum foil and the battery positive electrode material.

[0026] Furthermore, the solvent includes water and ethylene glycol, with a weight ratio of 3-5:1. Using this solvent allows graphene to be dispersed uniformly and is less prone to aggregation and precipitation, thus improving the dispersion ability of graphene.

[0027] A method for preparing an aluminum foil coating material includes the following steps:

[0028] S1. Mix graphene and solvent, stir ultrasonically, add activated carbon, and continue stirring to obtain the first slurry;

[0029] S2. Mix water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir to obtain the second slurry;

[0030] S3. Add the first slurry to the second slurry, ultrasonically stir, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

[0031] Graphene is uniformly dispersed in a solvent to prevent graphene agglomeration. Activated carbon is added, and a three-dimensional conductive network can be constructed through the encapsulation / coating of activated carbon microspheres and graphene on the surface of activated carbon particles, as well as the electrical connections between different activated carbon fibers. Through the effective synergistic effect of multiple carbon materials, the conductivity, pore structure and pore size distribution of the material are improved.

[0032] Aqueous conductive resin, polyaniline, and eucommia gum can crosslink or coalesce to form a blended composite system under the action of coupling agents and N-methylpyrrolidone. The aqueous conductive resin improves the material's adhesion and corrosion resistance, polyaniline improves conductivity, and eucommia gum improves acid and alkali resistance and hydrophobicity. The coupling agent also increases the density of the coating, thus significantly improving material performance. Adding a first slurry to a second slurry, which then encapsulates / coats the first slurry to form a composite structure, prevents agglomeration and precipitation between graphene and activated carbon, and improves the adhesion of graphene and activated carbon to aluminum foil. Adding an adhesive further enhances the interaction between the second and first slurries, making the three-dimensional conductive network constructed by graphene and activated carbon more stable, improving the conductivity of the aluminum foil, and enhancing its adhesion to the battery's positive electrode material.

[0033] Furthermore, ultrasonic stirring was performed sequentially at 1000 r / min, 800 r / min, and 500 r / min for 60 min, 40 min, and 30 min, respectively.

[0034] Furthermore, before using graphene and activated carbon, the process includes mechanical dispersion and grinding of the graphene and activated carbon. The mechanical dispersion speed is 2000-6000 r / min for 30-90 min, and the grinding speed is 1000-2000 r / min for 30-120 min. Mechanical dispersion and grinding of the activated carbon and graphene improve their uniformity in the system and prevent them from agglomerating and precipitating.

[0035] Example 1

[0036] A method for preparing an aluminum foil coating material includes the following steps:

[0037] Raw materials: 3g activated carbon, 5g graphene, 10g waterborne conductive resin, 1g polyaniline, 1g eucommia gum, 1g N-methylpyrrolidone, 0.5g coupling agent, 0.1g adhesive, and 30g solvent; wherein, the activated carbon includes activated carbon particles, activated carbon microspheres, and activated carbon fibers in a mass ratio of 2:1:1; the waterborne conductive resin includes waterborne polyacrylic resin, waterborne polyurethane dispersion, and waterborne epoxy resin in a mass ratio of 2:1:3; the coupling agent includes titanate coupling agent and silane coupling agent in a mass ratio of 1:2; the adhesive is polyvinylidene fluoride; and the solvent includes water and ethylene glycol in a mass ratio of 3:1.

[0038] S1. Graphene and activated carbon are mechanically dispersed and ground. The mechanical dispersion speed is 2000 r / min and the time is 30 min. The grinding speed is 1000 r / min and the time is 30 min.

[0039] S2. Mix graphene and solvent, ultrasonically stir at 1000 r / min for 60 min, then add activated carbon and continue stirring to obtain the first slurry;

[0040] S3. Mix the water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir at 800 r / min for 40 min to obtain the second slurry;

[0041] S4. Add the first slurry to the second slurry, ultrasonically stir at 500 r / min for 30 min, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

[0042] Example 2

[0043] A method for preparing an aluminum foil coating material includes the following steps:

[0044] Raw materials: 5g activated carbon, 8g graphene, 15g waterborne conductive resin, 3g polyaniline, 2g eucommia gum, 3g N-methylpyrrolidone, 0.8g coupling agent, 0.5g adhesive, and 35g solvent; wherein, the activated carbon includes activated carbon particles, activated carbon microspheres, and activated carbon fibers in a mass ratio of 2:1:1; the waterborne conductive resin includes waterborne polyacrylic acid resin, waterborne polyurethane dispersion, and waterborne epoxy resin in a mass ratio of 2:1:3; the coupling agent includes titanate coupling agent and silane coupling agent in a mass ratio of 1:2.5; the adhesive is polyacrylic acid; and the solvent includes water and ethylene glycol in a mass ratio of 3.5:1.

[0045] S1. Graphene and activated carbon are mechanically dispersed and ground. The mechanical dispersion speed is 3000 r / min and the time is 40 min. The grinding speed is 1200 r / min and the time is 40 min.

[0046] S2. Mix graphene and solvent, ultrasonically stir at 1000 r / min for 60 min, then add activated carbon and continue stirring to obtain the first slurry;

[0047] S3. Mix the water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir at 800 r / min for 40 min to obtain the second slurry;

[0048] S4. Add the first slurry to the second slurry, ultrasonically stir at 500 r / min for 30 min, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

[0049] Example 3

[0050] A method for preparing an aluminum foil coating material includes the following steps:

[0051] Raw materials: 7g activated carbon, 10g graphene, 18g waterborne conductive resin, 2g polyaniline, 4g eucommia gum, 3g N-methylpyrrolidone, 1.2g coupling agent, 0.8g adhesive, and 40g solvent; wherein, the activated carbon includes activated carbon particles, activated carbon microspheres, and activated carbon fibers in a mass ratio of 2:1:1; the waterborne conductive resin includes waterborne polyacrylic resin, waterborne polyurethane dispersion, and waterborne epoxy resin in a mass ratio of 2:1:3; the coupling agent includes titanate coupling agent and silane coupling agent in a mass ratio of 1:3; the adhesive is polyvinyl alcohol; and the solvent includes water and ethylene glycol in a mass ratio of 4:1.

[0052] S1. Graphene and activated carbon are mechanically dispersed and ground. The mechanical dispersion speed is 5000 r / min and the time is 50 min. The grinding speed is 1500 r / min and the time is 60 min.

[0053] S2. Mix graphene and solvent, ultrasonically stir at 1000 r / min for 60 min, then add activated carbon and continue stirring to obtain the first slurry;

[0054] S3. Mix the water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir at 800 r / min for 40 min to obtain the second slurry;

[0055] S4. Add the first slurry to the second slurry, ultrasonically stir at 500 r / min for 30 min, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

[0056] Example 4

[0057] A method for preparing an aluminum foil coating material includes the following steps:

[0058] Raw materials: 8g activated carbon, 12g graphene, 20g waterborne conductive resin, 5g polyaniline, 5g eucommia gum, 5g N-methylpyrrolidone, 1.5g coupling agent, 1g adhesive, and 50g solvent; wherein, the activated carbon includes activated carbon particles, activated carbon microspheres, and activated carbon fibers in a mass ratio of 2:1:1; the waterborne conductive resin includes waterborne polyacrylic acid resin, waterborne polyurethane dispersion, and waterborne epoxy resin in a mass ratio of 2:1:3; the coupling agent includes titanate coupling agent and silane coupling agent in a mass ratio of 1:4; the adhesive is polyvinylidene fluoride, polyacrylic acid, and polyvinyl alcohol; and the solvent includes water and ethylene glycol in a mass ratio of 5:1.

[0059] S1. Graphene and activated carbon are mechanically dispersed and ground. The mechanical dispersion speed is 6000 r / min and the time is 90 min. The grinding speed is 2000 r / min and the time is 120 min.

[0060] S2. Mix graphene and solvent, ultrasonically stir at 1000 r / min for 60 min, then add activated carbon and continue stirring to obtain the first slurry;

[0061] S3. Mix the water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir at 800 r / min for 40 min to obtain the second slurry;

[0062] S4. Add the first slurry to the second slurry, ultrasonically stir at 500 r / min for 30 min, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

[0063] Example 5

[0064] A method for preparing an aluminum foil coating material includes the following steps:

[0065] S1. Mix graphene and solvent, ultrasonically stir at 1000 r / min for 60 min, then add activated carbon and continue stirring to obtain the first slurry;

[0066] S2. Mix the water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir at 800 r / min for 40 min to obtain the second slurry;

[0067] S3. Add the first slurry to the second slurry, ultrasonically stir at 500 r / min for 30 min, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

[0068] The raw materials for the aluminum foil coating material in this embodiment are the same as those in Example 4.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that the activated carbon in this example only includes activated carbon particles.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that the activated carbon in this example consists only of activated carbon microspheres.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 1 is that the activated carbon in this example only includes activated carbon fibers.

[0075] Comparative Example 4

[0076] The difference between this comparative example and Example 1 is that the aluminum foil coating material does not include activated carbon.

[0077] Comparative Example 5

[0078] The difference between this comparative example and Example 1 is that the aluminum foil coating material does not include graphene.

[0079] Comparative Example 6

[0080] The difference between this comparative example and Example 1 is that the aluminum foil coating material does not include polyaniline.

[0081] Comparative Example 7

[0082] The difference between this comparative example and Example 1 is that the aluminum foil coating material does not include water-based conductive resin.

[0083] Comparative Example 8

[0084] The difference between this comparative example and Example 1 is that the mass ratio of activated carbon particles, activated carbon microspheres and activated carbon fibers in the activated carbon is 1:1:1.

[0085] Comparative Example 9

[0086] The difference between this comparative example and Example 1 is that the mass ratio of activated carbon particles, activated carbon microspheres and activated carbon fibers in the activated carbon is 1:1:2.

[0087] Test results

[0088] The performance tests of the finished products from the examples and comparative examples are as follows:

[0089] 1. Electrode conductivity

[0090] The coating materials of the examples and comparative examples were uniformly coated on PET film, cut into small circular pieces, and the actual conductivity on the electrode was simulated and tested.

[0091] 2. Adhesion to the current collector

[0092] The coating materials of the examples and comparative examples were uniformly coated onto aluminum foil to form simulated electrodes, and peel strength tests were conducted.

[0093] 3. Electrode tolerance

[0094] The coating materials of the examples and comparative examples were uniformly coated on aluminum foil to form simulated electrodes. The electrodes were baked in an oven at 105°C for 20 minutes, then removed and placed in a glove box. The surface of the electrodes was wiped with a cotton ball dipped in electrolyte or N-methylpyrrolidone solution until the aluminum foil was visible.

[0095] 4. Dispersion stability

[0096] Dispersion stability test method: At a temperature of 25℃, 1L of sample is placed in a 1.5L graduated glass beaker and stirred for 10min. Then, it is allowed to stand for 30d, and samples are taken from the top and bottom of the sample at the initial, 7d, 15d, 20d, and 30d to test the average particle size.

[0097] Table 1 Test Results

[0098]

[0099]

[0100] As shown in Table 1, the embodiments exhibit higher conductivity, peel strength, and abrasion resistance compared to the comparative examples, indicating that the coating material of the embodiments has better electrochemical performance, adhesion, and corrosion resistance. Notably, the electrodes showed greater peel strength after immersion in the electrolyte. This is because the swelling of the aqueous conductive resin and adhesive by the electrolyte causes entanglement or van der Waals forces, gradually fusing them together, resulting in superior electrochemical performance of the battery.

[0101] Compared to Example 1, Comparative Examples 1-3 showed decreased conductivity, peel strength, and number of wiping cycles. This indicates that diversification of activated carbon can optimize material performance. Comparative Examples 4-9 showed lower conductivity, peel strength, and number of wiping cycles compared to Example 1. This indicates that there is a synergistic effect between the raw materials, which can enhance material performance.

[0102] Table 2 Results of dispersion stability test

[0103]

[0104]

[0105] As shown in Table 2, the average particle size at the top of the sample decreased gradually over time, while the average particle size at the bottom of the sample increased gradually over time. This is because activated carbon and graphene in the material agglomerate and gradually precipitate, resulting in a decrease in the average particle size at the top and an increase in the average particle size at the bottom. Specifically, after 30 days of standing, the average particle size at the top of the coated material decreased by 0.08-0.11 μm, while the average particle size at the bottom increased by 0.11-0.17 μm. The small change in average particle size indicates that the graphene and activated carbon in the material did not agglomerate significantly, demonstrating the advantage of stable dispersion.

[0106] Compared to Example 1, Comparative Examples 1-5 showed a greater reduction in average particle size at the top of the samples and a greater increase in average particle size at the bottom, indicating that the combination of activated carbon and graphene can reduce their agglomeration and settling. Comparative Examples 6-9, compared to Example 1, showed a significant reduction in average particle size at the top of the samples and a significant increase in average particle size at the bottom. This indicates that the ratio of polyaniline, waterborne conductive resin, and activated carbon can reduce the agglomeration of activated carbon and graphene, and improve the uniformity of their dispersion in the material.

[0107] In summary, this invention provides an aluminum foil coating material with strong adhesion, high conductivity, good mechanical properties, and excellent solvent resistance. Its application in aluminum foil coatings has a positive and beneficial effect on improving the cycle life of lithium batteries, increasing the energy density of lithium batteries, and enhancing the rate performance of lithium batteries.

[0108] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An aluminum foil coating material, characterized in that: It includes the following raw materials by weight: 3-8 parts activated carbon, 5-12 parts graphene, 10-20 parts water-based conductive resin, 1-5 parts polyaniline, 1-5 parts eucommia gum, 1-5 parts N-methylpyrrolidone, 0.5-1.5 parts coupling agent, 0.1-1 part adhesive and 30-50 parts solvent; The activated carbon includes activated carbon particles, activated carbon microspheres and activated carbon fibers, and the weight ratio of the three is 2:1:1; The waterborne conductive resin includes waterborne acrylic resin, waterborne polyurethane dispersion and waterborne epoxy resin, and the weight ratio of the three is 2:1:

3.

2. The aluminum foil coating material according to claim 1, characterized in that: The coupling agent includes titanate coupling agent and silane coupling agent, and the weight ratio of the two is 1:2-4. The silane coupling agent includes one or more of KH550, KH560, KH570, KH580, KH590, KH602 and KH792.

3. The aluminum foil coating material according to claim 1, characterized in that: The adhesive includes one or more of polyvinylidene fluoride, polyacrylic acid, and polyvinyl alcohol.

4. The aluminum foil coating material according to claim 1, characterized in that: The solvent includes water and ethylene glycol, and the weight ratio of the two is 3-5:

1.

5. The method for preparing the aluminum foil coating material according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Mix graphene and solvent, stir ultrasonically, add activated carbon, and continue stirring to obtain the first slurry; S2. Mix water-based conductive resin, polyaniline, eucommia gum, N-methylpyrrolidone and coupling agent, and ultrasonically stir to obtain the second slurry; S3. Add the first slurry to the second slurry, ultrasonically stir, add the remaining raw materials, stir and mix to obtain the aluminum foil coating material.

6. The method for preparing the aluminum foil coating material according to claim 5, characterized in that: The ultrasonic stirring was performed at 1000 r / min, 800 r / min, and 500 r / min for 60 min, 40 min, and 30 min, respectively.

7. The method for preparing the aluminum foil coating material according to claim 5, characterized in that: Before using graphene and activated carbon, the process also includes mechanical dispersion and grinding of graphene and activated carbon. The mechanical dispersion speed is 2000-6000 r / min and the time is 30-90 min. The grinding speed is 1000-2000 r / min and the time is 30-120 min.

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