Preparation method of carbon-coated aluminum foil conductive carbon paste for power battery
By optimizing the composition of conductive carbon paste and the coating process, the defects of water-based carbon-coated aluminum foil in the coating process were solved, resulting in high-performance carbon-coated aluminum foil and improving the battery performance and stability of lithium-ion batteries.
Patent Information
- Application Number
- CN202511317541.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2026-02-03
AI Technical Summary
Existing water-based conductive carbon paste for coated aluminum foil is prone to problems such as pinholes and sagging during coating and drying, mainly due to the high surface tension of water, resulting in poor wettability with the aluminum foil substrate.
A formulation containing binder, conductive carbon material, solvent and substrate wetting agent is used to prepare conductive carbon paste by stirring and sand milling. After coating on the surface of aluminum foil, it is dried to optimize the rheology and adhesion of the paste. The substrate wetting agent is used to reduce interfacial tension and solve coating defects.
The prepared carbon-coated aluminum foil has a uniform and defect-free surface, low contact resistance, and high peel strength, which improves the performance and stability of lithium-ion batteries and extends their service life.
Smart Images
Figure BDA0005597520320000061
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium-ion power battery, and relates to a preparation method of conductive carbon paste for carbon-coated aluminum foil. BACKGROUND
[0002] The current collector plays a crucial role in lithium-ion batteries. In the positive electrode of a lithium-ion battery, the performance of the current collector directly affects the overall performance of the battery. Carbon-coated aluminum foil, as an innovative current collector material, has the advantage of coating conductive carbon material on the surface of aluminum foil, thereby achieving multiple performance improvements. First, carbon-coated aluminum foil provides excellent static conductivity. Due to the addition of conductive carbon material, the conductivity of the aluminum foil surface is significantly enhanced, which enables the battery to transmit current more efficiently during charging and discharging. This not only improves the output power of the battery, but also reduces the internal resistance of the battery, thereby prolonging the service life of the battery. Second, carbon-coated aluminum foil can significantly reduce the contact resistance between the positive active material and the current collector. The contact between the traditional current collector and the active material often has a large resistance, which will cause the performance of the battery to decrease. Carbon-coated aluminum foil effectively reduces the contact resistance by increasing the contact area between the conductive carbon material and the active material, so that the battery can make full use of the energy storage capacity of the active material. In addition, carbon-coated aluminum foil also increases the wettability and adhesion of the positive active material. The improvement of wettability enables the electrolyte to be more uniformly distributed on the surface of the active material, thereby improving the charging and discharging efficiency of the battery. The enhancement of adhesion ensures that the active material will not fall off from the current collector during charging and discharging, ensuring the stability and reliability of the battery. Finally, the use of carbon-coated aluminum foil can also improve the consistency of the battery. Since carbon-coated aluminum foil can be uniformly coated on the surface of the aluminum foil, the performance of the current collector in each battery cell is relatively stable, which enables the battery pack to exhibit better consistency when used in parallel or series. This is of great significance to improve the overall performance of the battery pack and prolong the service life of the battery pack.
[0003] The technical indicators for carbon-coated aluminum foil conductive carbon paste mainly include contact angle, carbon paste adhesion, electrolyte resistance, peeling strength (between the positive active material and the current collector), and surface contact resistance. The existing water-based carbon-coated aluminum foil conductive carbon paste is mainly composed of three materials: binder, conductive carbon material, and solvent. It can generally meet the customer's requirements for stability, adhesion, electrolyte resistance, surface contact resistance, and peeling strength performance.
[0004] However, the water-based carbon-coated aluminum foil conductive carbon paste has many problems such as shrinkage and sagging during coating and drying. The main reason is that the surface tension of water is relatively large (about 7.2 x 10 -4 N / m), while the aluminum foil tension is (3.0-4.0) x 10 -4The surface tension of the conductive carbon paste needs to be reduced to between N / m. To maintain the wettability of the paste with the aluminum foil substrate, a substrate wetting agent needs to be added as an additive to reduce the surface tension of the conductive carbon paste and maintain wetting and stability during the evaporation of moisture. Therefore, it is essential to develop a carbon-coated aluminum foil coating with good wettability with the aluminum foil substrate. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing conductive carbon paste for carbon-coated aluminum foil, and the carbon-coated aluminum foil made from the conductive carbon paste has excellent performance.
[0006] The preparation method of the conductive carbon paste in this invention is as follows:
[0007] A conductive paste for carbon-coated aluminum foil is prepared from the following components in parts by weight: 3-7 parts binder, 3-7 parts conductive carbon material, 84.7-94.7 parts solvent, and 0.1-2.5 parts substrate wetting agent, wherein:
[0008] The adhesive is one or more of the following: water-soluble acrylic resin, waterborne polyurethane, styrene-butadiene rubber emulsion, carboxymethyl cellulose, polyvinyl alcohol, epoxidized natural rubber, and sodium alginate.
[0009] The conductive carbon material is one or more of the following: conductive carbon black Super P, Ketjen black, highly conductive graphite nanosheets, graphene, multi-walled carbon nanotubes, acetylene black, and carbon quantum dots.
[0010] The solvent is composed of water and an organic solvent, including one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol. The water comprises 69.7-79.7 parts by weight, and the organic solvent comprises 10-20 parts by weight.
[0011] The wetting agent is one or more of the following: SN-250, SN-262, Disper850, X1070, X-1040, and L-303. It is mainly a polyether siloxane copolymer, a fluorocarbon wetting agent, and a polyether; the addition amount is 1.5-2.5 parts.
[0012] The water-based adhesive and substrate wetting agent are dissolved in a solvent while stirring. Then, the conductive carbon material is slowly added. After the mixture is well dispersed, it is added to a sand mill and ground until the particle size meets the requirements to obtain conductive carbon slurry.
[0013] Furthermore, the carbon-coated aluminum foil consists of an aluminum foil substrate and a carbon coating layer. The carbon coating layer is obtained by coating the surface of the aluminum foil substrate with conductive carbon paste. The water-based conductive carbon paste for carbon-coated aluminum foil is coated onto the current collector aluminum foil using a gravure or micro-gravure printing plate. After coating, it is dried at a temperature of 100-130°C to obtain the carbon-coated aluminum foil.
[0014] In conductive carbon paste formulations, the addition of wetting agents is a crucial step in optimizing paste rheology, substrate adhesion, and printing / coating performance. Its core function is to reduce the interfacial tension between the carbon paste and the substrate, especially aluminum foil, thus resolving issues such as pinholes, pores, and edge warping caused by carbon powder (or conductive fillers like carbon nanotubes and graphene) agglomeration. Simultaneously, it assists dispersants in improving the dispersion stability of conductive fillers. The following detailed explanation covers the addition logic, key points, common types, and precautions to help achieve superior conductive carbon paste performance.
[0015] The main components of conductive carbon paste are conductive fillers (carbon powder, CNT, graphene, etc.), binders (resins), solvents, and dispersants. The core value of wetting agents is their "bridging role": improving the "solid-liquid-gas" three-phase interface and reducing the surface tension of the carbon paste (liquid), enabling it to spread quickly and evenly on the surface of the substrate (solid), thus avoiding the "ink-not-sticking" phenomenon caused by the low surface energy of the substrate (such as PET).
[0016] Assisted dispersion and stabilization: In synergy with dispersants, it penetrates into the interior of conductive filler agglomerates, weakens the van der Waals forces between particles, and reduces the probability of secondary agglomeration after dispersion; Optimized processing performance: Reduces "screen clogging" and "line breakage" during printing (such as screen printing and gravure printing), or "stripes" during coating (such as scraping and roller coating), ensuring the uniformity of carbon paste film formation (directly affecting the consistency of conductivity); Improved film adhesion: Promotes interfacial bonding between resin and substrate, and avoids film peeling after curing due to "weak interfacial bonding".
[0017] Key points for adding wetting agents: Follow the "effective concentration range" to avoid excessive side effects. The amount of wetting agent added to conductive carbon paste is generally 0.1% to 2% of the total mass of carbon paste. Specific surface area of conductive fillers: The larger the specific surface area (e.g., carbon nanotubes, graphene, specific surface area > 500m²), the better. 2 For carbon black (e.g., acetylene black, with a specific surface area of approximately 100 m² / g), more wetting agent is needed to cover the particle surface, and the addition amount can be increased to 0.5%–2%; for conventional conductive carbon black (e.g., acetylene black, with a specific surface area of approximately 100 m² / g), more wetting agent is needed to cover the particle surface, and the addition amount can be increased to 0.5%–2%; 2 / g), 0.1% to 0.8% is sufficient.
[0018] Compared with the prior art, the beneficial effects of this invention are reflected in the following: the conductive carbon paste disclosed in this invention includes a substrate wetting agent, and by adding the substrate wetting agent, this invention prepares a high-performance carbon-coated aluminum foil. The surface contact resistance range of the carbon-coated aluminum foil for lithium-ion batteries prepared in this application is 3.9-0.3mΩ; its peel strength with the positive electrode active material of the lithium battery ranges from 153.7 to 207.6 N / m; and the carbon-coated aluminum foil for lithium batteries prepared in this application has a fine and uniform surface without obvious defects. Detailed Implementation
[0019] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.
[0020] Example 1
[0021] Preparation of conductive carbon paste for carbon-coated aluminum foil:
[0022] Dissolve 5 parts of water-based adhesive and 0.3 parts of substrate wetting agent SN-250 in 89.7 parts of solvent while stirring. Then slowly add 5 parts of conductive carbon material. After the mixture is well dispersed, add it to a sand mill and grind it to a fineness of 15μm to obtain conductive carbon slurry.
[0023] Preparation of carbon-coated aluminum foil:
[0024] Conductive carbon paste is coated onto current collector aluminum foil using a gravure or microgravure coating equipment, dried at a drying temperature of 100-130℃, and cured to obtain carbon-coated aluminum foil, which is marked as S1.
[0025] Example 2
[0026] Preparation of conductive carbon paste for carbon-coated aluminum foil:
[0027] Dissolve 5 parts of water-based adhesive and 0.3 parts of substrate wetting agent SN-262 in 89.7 parts of solvent while stirring. Then slowly add 5 parts of conductive carbon material. After the mixture is well dispersed, add it to a sand mill and grind it to a fineness of 15μm to obtain conductive carbon slurry.
[0028] Preparation of carbon-coated aluminum foil:
[0029] Conductive carbon paste is coated onto current collector aluminum foil using a gravure or micro-gravure coating equipment, dried at a drying temperature of 100-130℃, and cured to obtain carbon-coated aluminum foil, marked as S2.
[0030] Example 3
[0031] Preparation of conductive carbon paste for carbon-coated aluminum foil:
[0032] Dissolve 5 parts of water-based adhesive and 0.3 parts of substrate wetting agent Disper850 in 89.7 parts of solvent while stirring. Then slowly add 5 parts of conductive carbon material. After the mixture is well dispersed, add it to a sand mill and grind it to a fineness of 15μm to obtain conductive carbon slurry.
[0033] Preparation of carbon-coated aluminum foil:
[0034] Conductive carbon paste is coated onto current collector aluminum foil using a gravure or micro-gravure coating equipment, dried at a drying temperature of 100-130℃, and cured to obtain carbon-coated aluminum foil, marked as S3.
[0035] Example 4
[0036] Preparation of conductive carbon paste for carbon-coated aluminum foil:
[0037] Dissolve 5 parts of water-based adhesive and 0.3 parts of substrate wetting agent X1070 in 89.7 parts of solvent while stirring. Then slowly add 5 parts of conductive carbon material. After the mixture is well dispersed, add it to a sand mill and grind it to a fineness of 15μm to obtain conductive carbon slurry.
[0038] Preparation of carbon-coated aluminum foil:
[0039] Conductive carbon paste is coated onto current collector aluminum foil using a gravure or microgravure coating equipment, dried at a drying temperature of 100-130℃, and cured to obtain carbon-coated aluminum foil, marked as S4.
[0040] Example 5
[0041] Preparation of conductive carbon paste for carbon-coated aluminum foil:
[0042] Dissolve 5 parts of water-based adhesive and 0.3 parts of substrate wetting agent X-1040 in 89.7 parts of solvent while stirring. Then slowly add 5 parts of conductive carbon material. After the mixture is well dispersed, add it to a sand mill and grind it to a fineness of 15μm to obtain conductive carbon slurry.
[0043] Preparation of carbon-coated aluminum foil:
[0044] Conductive carbon paste is coated onto current collector aluminum foil using a gravure or micro-gravure coating equipment, dried at a drying temperature of 100-130℃, and cured to obtain carbon-coated aluminum foil, marked as S5.
[0045] Example 6
[0046] Preparation of conductive carbon paste for carbon-coated aluminum foil:
[0047] Dissolve 5 parts of water-based adhesive and 0.3 parts of substrate wetting agent L-303 in 89.7 parts of solvent while stirring. Then slowly add 5 parts of conductive carbon material. After the mixture is well dispersed, add it to a sand mill and grind it to a fineness of 15μm to obtain conductive carbon slurry.
[0048] Preparation of carbon-coated aluminum foil:
[0049] Conductive carbon paste is coated onto current collector aluminum foil using a gravure or microgravure coating equipment, dried at a drying temperature of 100-130℃, and cured to obtain carbon-coated aluminum foil, marked as S6.
[0050] Comparative Example 1
[0051] Preparation of conductive carbon paste for carbon-coated aluminum foil:
[0052] Dissolve 5 parts of water-based adhesive in 90 parts of solvent while stirring, then slowly add 5 parts of conductive carbon material. After the mixture is well dispersed, add it to a sand mill and grind it to a fineness of 15μm to obtain conductive carbon slurry.
[0053] Preparation of carbon-coated aluminum foil:
[0054] Conductive carbon paste is coated onto current collector aluminum foil using a gravure or microgravure coating equipment, dried at a drying temperature of 100-130℃, and cured to obtain carbon-coated aluminum foil, marked as X1.
[0055] Performance testing experiment
[0056] The carbon-coated aluminum foils prepared in the above embodiments and comparative examples were subjected to the following performance tests:
[0057] Peel strength: The lithium iron phosphate cathode slurry was sequentially coated onto the carbon-coated aluminum foil for lithium batteries. After drying, the tensile strength was tested using a tensile tester according to the method shown in GB2792-2014 and converted to N / m. The test results are shown in Table 1.
[0058] Electrolyte resistance test: The above-mentioned carbon-coated aluminum foil for lithium batteries was wiped with a cotton swab dipped in electrolyte according to the standard number of wiping cycles. The number of electrolyte wiping cycles was tested and the test results are shown in Table 1.
[0059] Surface contact resistance: The surface contact resistance of the positive electrode water-based carbon-coated aluminum foil coating was tested using an ST-2258C four-probe tester. The test results are shown in Table 1.
[0060] Contact angle: The resistance of the carbon-coated aluminum foil for the lithium battery was measured using an SZ-CAMC33 contact angle measuring instrument. The results are shown in Table 1.
[0061] Table 1 Sample Test Results
[0062]
Claims
1. A conductive carbon paste for power batteries with carbon-coated aluminum foil, characterized in that, The conductive carbon paste is prepared from the following components in parts by weight: 3-7 parts binder; 3-7 parts conductive carbon material; 84.7-94.7 parts solvent; and 0.1-2.5 parts substrate wetting agent.
2. The conductive carbon paste for carbon-coated aluminum foil according to claim 1, characterized in that, The adhesive includes one or more of the following: water-soluble acrylic resin, waterborne polyurethane, styrene-butadiene rubber emulsion, carboxymethyl cellulose, polyvinyl alcohol, epoxidized natural rubber, and sodium alginate.
3. The conductive carbon paste for carbon-coated aluminum foil according to claim 2, characterized in that, The conductive carbon material includes one or more of the following: conductive carbon black Super P, Ketjen black, highly conductive graphite nanosheets, graphene, multi-walled carbon nanotubes, acetylene black, and carbon quantum dots.
4. The conductive carbon paste for carbon-coated aluminum foil according to claim 3, characterized in that, The solvent includes water and an organic solvent. The organic solvent includes one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol. The water comprises 69.7-79.7 parts by weight, and the organic solvent comprises 10-20 parts by weight.
5. The conductive carbon paste for carbon-coated aluminum foil according to claim 4, characterized in that, The wetting agent is one or more of the following: SN-250, SN-262, Disper850, X1070, X-1040, and L-303.
6. The conductive carbon paste for carbon-coated aluminum foil according to claim 5, characterized in that, The amount of the wetting agent added is 0.1-1.0%.
7. The method for preparing conductive carbon paste for carbon-coated aluminum foil according to any one of claims 1 to 6, characterized in that: Includes the following steps: The water-based adhesive and substrate wetting agent are dissolved in a solvent under stirring, and then the conductive carbon material is slowly added. After the mixture is well dispersed, it is added to a sand mill and ground until the particle size meets the requirements to obtain conductive carbon paste. The water-based carbon-coated aluminum foil conductive carbon paste is coated onto the current collector aluminum foil using a gravure or micro-gravure plate. After coating, it is dried at a temperature of 100-130℃ to obtain carbon-coated aluminum foil.
8. The method for preparing conductive carbon paste for carbon-coated aluminum foil according to any one of claims 1 to 6, characterized in that: The wetting agent is a polyether siloxane copolymer, a fluorocarbon wetting agent, or a polyether; the addition amount is 1.5-2.5 parts.