A carbon-coated aluminum foil with high adhesion and a preparation method and application thereof

Abstract

The application discloses carbon-coated aluminum foil with high adhesive force and a preparation method and application thereof. The carbon-coated aluminum foil with high adhesive force comprises a carbon-coated layer, the carbon-coated layer contains carbon conductive agent, nano-cellulose and nano-cellulose composite material, and the nano-cellulose composite material is formed by compounding raw materials containing nano-cellulose and heat-conducting and conductive nano-materials. The application adds conventional nano-cellulose and nano-cellulose composite material in carbon-coated slurry, decomposes the nano-cellulose composite material through high-temperature baking, leaves the position of cellulose on the surface of the decomposed carbon-coated aluminum foil, increases the roughness of the surface of the carbon-coated aluminum foil, and when the positive active material is coated on the surface of the carbon-coated aluminum foil, the positive active material and the carbon-coated layer are embedded together after rolling, and the combination is more compact, that is, the adhesive force between the positive active material and the carbon-coated layer is increased.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a carbon-coated aluminum foil with high adhesion, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries (LIBs) have been widely adopted in various fields such as consumer electronics, transportation, power tools, and energy storage. Aluminum foil current collectors refer to the process of combining aluminum foil with other materials (such as paper, plastic film, coatings, etc.) to form a composite material. This technology can endow aluminum foil with new properties and functions to meet the needs of different industries. To improve the performance of lithium batteries, the lithium battery industry employs a strategy of carbon-coated current collectors to increase the rate of operation and overall performance.

[0003] However, the low adhesion and low toughness of carbonized aluminum foil current collectors affect subsequent operations such as slitting, rewinding, and coating of positive electrode active materials. Therefore, it is necessary to develop and manufacture a carbonized aluminum foil with high adhesion to ensure a series of operations such as slitting, rewinding, and coating of positive electrode slurry after carbonization. Summary of the Invention

[0004] To improve the adhesion of carbon-coated aluminum foil, this invention provides a carbon-coated aluminum foil with high adhesion, its preparation method, and its application. The technical solution adopted by this invention is as follows:

[0005] A carbon-coated aluminum foil with high adhesion, the carbon-coated aluminum foil comprising a carbon coating layer, the carbon coating layer containing a carbon conductive agent, nanocellulose and a nanocellulose composite material, the nanocellulose composite material being formed by combining raw materials containing nanocellulose and thermally and electrically conductive nanomaterials;

[0006] The weight of the nanocellulose is 5-15% of the weight of the carbon conductive agent;

[0007] The weight ratio of the nanocellulose and the nanocellulose composite material is 1:0.2~0.67;

[0008] The thermally and electrically conductive nanomaterials are at least one of carbon nanotubes, transition metal dichalcogenides, boron nitride nanomaterials, and graphene.

[0009] Preferably, the nanocellulose composite material is composed of nanocellulose and carbon nanotubes;

[0010] Preferably, the weight ratio of nanocellulose to carbon nanotubes in the nanocellulose composite material is 1:(1.5~5);

[0011] Preferably, the weight ratio of nanocellulose to carbon nanotubes in the nanocellulose composite material is 1:3;

[0012] Preferably, the carbon nanotubes are single-walled carbon nanotubes.

[0013] Optionally, the carbon conductive agent comprises carbon powder;

[0014] Preferably, the carbon conductive agent comprises carbon powder and graphite powder, wherein the weight ratio of carbon powder to graphite powder is 7~9:1~3.

[0015] A method for preparing carbon-coated aluminum foil with high adhesion includes the following steps:

[0016] Step 1) Combining nanocellulose with thermally and electrically conductive nanomaterials to prepare nanocellulose composite materials;

[0017] Step 2) Mix the raw materials containing nanocellulose composite material, nanocellulose, carbon conductive agent and binder evenly to obtain carbon coating slurry;

[0018] Step 3) Apply the carbon coating slurry onto the aluminum foil to form a carbon coating layer, thus obtaining carbon-coated aluminum foil.

[0019] Optionally, the nanocellulose is prepared by using plant cellulose as raw material and through an acid treatment method.

[0020] Optionally, step one) of preparing a nanocellulose composite material by combining nanocellulose and thermally and electrically conductive nanomaterials includes the following steps:

[0021] Nanocellulose and thermally and electrically conductive nanomaterials are mixed and ground; then the ground mixture is ultrasonically treated in a solvent to obtain a nanocellulose composite material.

[0022] Preferably, the thermally and electrically conductive nanomaterial is a carbon nanotube;

[0023] Preferably, the diameter of the carbon nanotube is 1-5 nm and the length of the carbon nanotube is 40-120 nm;

[0024] Preferably, nanocellulose and carbon nanotubes are mixed and ball-milled at 800-1200 r / min for 40-80 min, with the size of the ball-milled zircon beads being 0.05-0.5 mm; then the milled mixture is ultrasonically treated in a solvent for 90-150 min at an ultrasonic frequency of 2000-4500 Hz to obtain a nanocellulose composite material.

[0025] Optionally, the raw materials in step two may further include a binder;

[0026] Preferably, step two) involves uniformly mixing the raw materials comprising nanocellulose composite material, nanocellulose, carbon conductive agent, and binder, including the following steps:

[0027] a) Mix the binder and a portion of the carbon conductive agent evenly to obtain mixture I; then add nanocellulose to mixture I and mix evenly to obtain mixture II;

[0028] b) Add the remaining carbon conductive agent to mixture II to obtain mixture III, and then add the nanocellulose composite material to mixture III to obtain mixture IV;

[0029] c) Adjust the pH of mixture IV to 5-7 to obtain the carbon-coated slurry;

[0030] Preferably, the adhesive is at least one selected from acrylate, polyacrylic acid, modified polyacrylic acid, and waterborne polyurethane;

[0031] Preferably, in step a), the adhesive is diluted with water and then mixed evenly with a portion of the carbon conductive agent to obtain mixture I.

[0032] Optionally, step two may further include:

[0033] d) Add a wetting agent to the carbon coating slurry and mix thoroughly, wherein the wetting agent comprises at least one of polyether siloxane, modified polyether siloxane, and alcohol-based wetting agents;

[0034] Preferably, the amount of wetting agent added is 5-10% of the mass of the carbon coating slurry;

[0035] Preferably, step two further includes: homogenizing the carbon coating slurry.

[0036] The present invention also proposes the application of the above-mentioned carbon-coated aluminum foil with high adhesion in the preparation of battery cathodes.

[0037] A method for preparing a battery positive electrode includes the following steps:

[0038] The positive electrode material is coated onto a carbonized aluminum foil with high adhesion, then pressed together, and then heated to decompose and volatilize the nanocellulose composite material in the carbonized layer.

[0039] Preferably, the heating temperature of the heat treatment is 120~150℃, and the time is 6-8 minutes;

[0040] Preferably, the heating treatment is performed using an oven.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] This invention employs a strategy of adding conventional nanocellulose and nanocellulose composites to the carbon coating slurry. The nanocellulose composite is decomposed through high-temperature baking, leaving cellulose sites on the surface of the carbonized aluminum foil after decomposition, thus increasing the surface roughness of the carbonized aluminum foil. When the positive electrode active material is coated onto the carbonized aluminum foil surface, after rolling, the positive electrode active material becomes embedded in the carbonized layer, resulting in a tighter bond and increased adhesion between the positive electrode active material and the carbonized layer. Furthermore, this invention also contains a portion of conventional nanocellulose in the carbonized layer. The pyrolysis of this nanocellulose requires a high temperature; after oven drying, only the nanocellulose composite is decomposed, while the remaining conventional nanocellulose remains in the carbonized layer, reducing the deformation of the carbonized aluminum foil and increasing the toughness of the carbonized layer. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 A micrograph of the surface of the carbon-coated aluminum foil of Example 1 after heat treatment.

[0045] Figure 2 A micrograph of the surface of the carbon-coated aluminum foil in Comparative Example 3 after heat treatment.

[0046] Figure 3 The graph shows the thermogravimetric analysis results of the carbon-coated aluminum foil in Example 1. Detailed Implementation

[0047] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0048] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0049] All raw materials used in this invention are commercially available products. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention.

[0050] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0051] This invention proposes a carbon-coated aluminum foil with high adhesion, wherein the carbon-coated aluminum foil with high adhesion comprises a carbon coating layer, wherein the carbon coating layer contains a carbon conductive agent, nanocellulose and a nanocellulose composite material, wherein the nanocellulose composite material contains nanocellulose and thermally and electrically conductive nanomaterials.

[0052] The weight of the nanocellulose is 10% of the weight of the carbon conductive agent;

[0053] The weight ratio of the nanocellulose and the nanocellulose composite material is 1:0.2~0.67;

[0054] The carbon conductive agent comprises carbon powder; more preferably, the carbon conductive agent comprises carbon powder and graphite powder, wherein the weight ratio of carbon powder to graphite powder is 7~9:1~3.

[0055] This invention employs a strategy of adding conventional nanocellulose and nanocellulose composites to the carbon coating slurry. The nanocellulose composites are decomposed through high-temperature baking, leaving cellulose sites on the surface of the carbonized aluminum foil. This increases the surface roughness of the carbonized aluminum foil. When the positive electrode active material is coated onto the carbonized aluminum foil surface, after rolling, the positive electrode active material embeds itself into the carbonized layer, resulting in a tighter bond and increased adhesion between the positive electrode active material and the carbonized layer. Additionally, the carbonized layer contains a portion of conventional nanocellulose. These nanocelluloses have a high thermal decomposition rate; after oven drying, only the nanocellulose composite material decomposes, while the remaining conventional nanocellulose remains in the carbonized layer. This reduces the deformation of the carbonized aluminum foil and increases the toughness of the carbonized layer.

[0056] Nanocellulose is a novel biomaterial obtained by nanoprocessing plant cellulose. It possesses excellent mechanical properties, thermal stability, and biocompatibility, and is widely used in biomedicine, food, paper, textiles, building materials, and other fields.

[0057] The nanocellulose composite material of this invention achieves low-temperature decomposition of nanocellulose through a strategy of synthesizing thermally and electrically conductive nanomaterials. Due to the unique properties of thermally and electrically conductive nanomaterials, taking carbon nanotubes (CNTs) as an example: 1. High thermal conductivity: CNTs possess high thermal conductivity, enabling rapid heat transfer and accelerating the decomposition of nanocellulose bound to them. 2. High surface area: CNTs have a high surface area, providing ample contact area, promoting the interaction between nanocellulose and CNTs, and lowering the temperature required for nanocellulose decomposition. 3. Electronic conductivity: CNTs possess electronic conductivity, which can influence the electronic structure of nanocellulose, further reducing its decomposition temperature. Therefore, combining thermally and electrically conductive nanomaterials such as carbon nanotubes with nanocellulose can yield nanocellulose composite materials with low pyrolysis temperatures.

[0058] The above-mentioned method for preparing carbon-coated aluminum foil with high adhesion includes the following steps:

[0059] Step 1) Composite nanocellulose and thermally and electrically conductive nanomaterials are combined to obtain a nanocellulose composite material; the nanocellulose is prepared from plant cellulose through an acid treatment method. The composite method of nanocellulose and thermally and electrically conductive nanomaterials includes the following steps:

[0060] Nanocellulose and thermally and electrically conductive nanomaterials are mixed and ground; then the ground mixture is ultrasonically treated in a solvent to obtain a nanocellulose composite material. The binder is at least one of the following water-based materials: acrylate, polyacrylic acid, modified polyacrylic acid, or waterborne polyurethane.

[0061] Step 2) Mix the raw materials containing nanocellulose composite material, nanocellulose, carbon conductive agent and binder evenly to obtain carbon coating slurry; specifically including:

[0062] a) Mix the binder and a portion of the carbon conductive agent evenly to obtain mixture I; then add nanocellulose to mixture I and mix evenly to obtain mixture II;

[0063] b) Add the remaining carbon conductive agent to mixture II to obtain mixture III, and then add the nanocellulose composite material to mixture III to obtain mixture IV;

[0064] c) Adjust the pH of mixture IV to 5-7;

[0065] d) Then add a wetting agent to the carbon coating slurry and mix evenly. The wetting agent includes at least one of polyether siloxane, modified polyether siloxane, and alcohol wetting agent. Then homogenize twice using a homogenizer to obtain the carbon coating slurry.

[0066] Step 3) Apply the carbon coating slurry onto the aluminum foil to form a carbon coating layer, thus obtaining carbon-coated aluminum foil.

[0067] More preferably, in step one), the adhesive is diluted with water and then mixed evenly with a portion of the carbon conductive agent to obtain mixture I.

[0068] The present invention also proposes the application of the above-mentioned carbon-coated aluminum foil with high adhesion in the preparation of battery cathodes.

[0069] This invention improves the adhesion between the carbonized aluminum foil and the positive electrode material by increasing the surface roughness of the carbonized coating layer. Increasing the surface roughness of the coating effectively increases the amount of positive electrode material coated on the carbonized layer. After rolling, the two materials have greater interlocking force, resulting in greater electrode peeling force. This increase in surface roughness is achieved by decomposing the nanocellulose composite material present within the carbonized layer. The nanocellulose is mixed in the carbon slurry and coated onto the aluminum foil surface; the nanocellulose composite material is thus present in the carbonized layer. The carbonized aluminum foil is then passed through an oven at a temperature set at the decomposition and volatilization temperature of the nanocellulose composite material, typically 120-150°C. The oven length should be greater than 10m, and the heating time is 6-8 minutes. After baking, the nanocellulose in the coating decomposes and volatilizes. This results in textures left by the nanocellulose composite material appearing on the carbonized layer, both on the surface and within the coating. This significantly increases the roughness of the coating, greatly increasing the interlocking force between the positive electrode active material and the coating after rolling.

[0070] This invention improves the toughness of carbonized aluminum foil by adding conventional nanocellulose. The principle behind nanocellulose increasing the toughness of carbonized aluminum foil is based on: 1. The high strength and stiffness of nanocellulose: Nanocellulose possesses high strength and stiffness, providing strong mechanical support and improving the material's toughness. 2. The high surface area of ​​nanocellulose: Nanocellulose has a high surface area, providing a large contact area, promoting the interaction between materials, and improving the material's toughness. The pyrolysis temperature of conventional nanocellulose is 200-250℃. Therefore, after passing through a 120℃ oven, conventional nanocellulose is not affected and will still exist within the carbonized aluminum foil, playing a role in increasing the toughness of the carbonized aluminum foil.

[0071] The raw materials used in the following examples are as follows: PAA was purchased from Sinopharm Group, model AR (Shanghai Trial), ≥99.0% 500mL, Sinopharm code 80001418. Carbon powder was purchased from Shanghai Buding Chemical, model CABOT high abrasion-resistant carbon black N330. Graphite powder was purchased from Maclean Group, model: G810361 graphite powder, 99.95% metals basis. Graphene was purchased from Sinopharm Group, model 97% (Wokai) 500mg, Sinopharm code XW011034343980012.

[0072] Example 1

[0073] A method for preparing carbon-coated aluminum foil with high adhesion includes the following steps:

[0074] Step 1) Preparation of nanocellulose and nanocellulose composite materials:

[0075] This embodiment prepares nanocellulose by chemically corroding plant cellulose with a strong acid. Acid treatment is a commonly used chemical method for obtaining nanocellulose. The principle of acid treatment is to use acid to hydrolyze the glycosidic bonds of plant cellulose, destroying the crystalline structure of cellulose, thereby obtaining nanoscale cellulose. First, the plant cellulose is ground for 1 hour at a speed of 1000 rpm using 20 0.1 mm beads to pulverize the plant cellulose into small particles, increasing its surface area. Then, the plant cellulose powder is mixed with sulfuric acid (0.5 mM / L) at a weight ratio of 2:1 (sulfuric acid to cellulose). The reaction is carried out at room temperature (20°C) for 9 hours. After the reaction, the acid is neutralized, and the mixture is washed with deionized water to remove residual acid and other impurities. After drying at 50°C for 12 hours, nanocellulose is obtained.

[0076] Preparation of Nanocellulose Composite Material: The nanocellulose composite material of this invention utilizes a strategy of synthesizing thermally and electrically conductive nanomaterials to decompose nanocellulose at lower temperatures. The carbon nanotubes used are Merck Chemicals single-walled carbon nanotubes, 750522, 98% (Semiconducting). The nanocellulose composite material is prepared using a simple material processing method: ball milling and ultrasonic synthesis. The prepared nanocellulose and single-walled carbon nanotubes are mixed at a weight ratio of 1:3, ball-milled at 1000 r / min for 60 min, using 20 0.1 mm beads. The milled mixture is placed in a beaker and ultrasonically sonicated for 120 min at a frequency of 3500 Hz. The treated sample is then dried in a drying oven at 50°C for 12 hours to obtain the nanocellulose composite material for later use.

[0077] Step 2) S1 Mix deionized water and water-based PAA at a weight ratio of 3:1 to reduce the solid content of the adhesive; obtain diluted adhesive with a volume of 100L and a mass of 90kg.

[0078] S2 Add 1.5 kg of carbon powder and 1.5 kg of graphite powder to the diluted binder, and disperse at high speed of 2000-2600 rpm / min for 30 min in a 200L double-star mixing tank.

[0079] Add 0.15 kg of nanocellulose to S3 and disperse it in a 200 L double-star mixing tank at 1000-1500 rpm / min for 30 min.

[0080] Add 1.5 kg of carbon powder and 1.5 kg of graphite powder to S4 and disperse at high speed of 2000-2600 rpm / min for 60 min in a 200L double-star mixing tank.

[0081] Add 15kg of deionized water to S5 to reduce the slurry concentration, and disperse at high speed for 30 minutes in a 200L twin-star mixing tank at 2000-2600rpm / min.

[0082] Add NaOH solution to S6 and adjust the pH to 6, which is weakly acidic.

[0083] After the exothermic reaction is complete, add 0.1 kg of nanocellulose composite material and disperse it in a 200 L double-star stirred tank at 1000-1500 rpm / min for 60 min.

[0084] Add 9 kg of isopropanol as a wetting agent to S8, and stir at a low speed of 10-15 rpm / min for 30-45 minutes in a 200L double-star mixing tank before discharging.

[0085] S9 Homogenize the slurry twice in a homogenizer at a pressure of 300 bar to obtain a carbon-coated slurry.

[0086] Step 3) Apply the carbon coating slurry onto the aluminum foil to form a carbon coating layer with a thickness of 2 μm. This yields the carbon-coated aluminum foil.

[0087] The nanocellulose composite material in the aforementioned carbonized aluminum foil coating will decompose and volatilize after baking, such as... Figure 1 As shown, the texture left by the nanocellulose composite material will appear on the carbon coating layer. Figure 1 The black area inside the frame is the trace pattern left after the cellulose decomposes and curls up. These patterns exist not only on the surface of the coating but also inside the coating, which can greatly increase the roughness of the coating. After the positive electrode active material and the coating are rolled together, the interlocking force between the two will be greatly increased.

[0088] Thermogravimetric analysis was performed on the above-mentioned nanocellulose composite material, and the test results are as follows: Figure 3 As shown. Thermogravimetric analysis indicates that the carbon nanotube-cellulose nanocomposite can decompose at relatively low temperatures of around 100°C. The carbon nanotube-cellulose nanocomposite of this invention can decompose significantly at lower temperatures. The main principles are as follows: strong interfacial interactions (such as hydrogen bonds, van der Waals forces, or π-π stacking) form between carbon nanotubes and cellulose nanocomposite. These interactions may lead to localized stress concentration in the cellulose nanocomposite segments, causing thermal decomposition at lower temperatures. The addition of carbon nanotubes disrupts the ordered structure of cellulose nanocomposite, leading to a decrease in its thermal stability. Carbon nanotubes (CNTs) have high thermal conductivity, enabling rapid heat transfer and accelerating the decomposition of the cellulose nanocomposite to them. The high surface area of ​​both carbon nanotubes and CNTs provides a large contact area, promoting the interaction between cellulose nanocomposite and CNTs and lowering the temperature required for cellulose nanocomposite decomposition.

[0089] Example 2

[0090] Compared with Example 1, in step two of this example, the amount of conventional nanocellulose added is increased, so that the addition ratio of conventional nanocellulose: nanocellulose composite material is 3:1, and the other steps are the same as in Example 1.

[0091] Example 3

[0092] Compared with Example 1, in step two of this example, the amount of conventional nanocellulose added is increased, so that the addition ratio of conventional nanocellulose: nanocellulose composite material is 4:1, and the other steps are the same as in Example 1.

[0093] Example 4

[0094] Compared with Example 1, in step two of this example, the amount of conventional nanocellulose added is increased, so that the addition ratio of conventional nanocellulose: nanocellulose composite material is 5:1, and the other steps are the same as in Example 1.

[0095] Example 5

[0096] Compared to Example 1, in step one of this example, carbon nanotubes are replaced with an equal weight of graphene. The remaining steps are the same as in Example 1.

[0097] Example 6

[0098] Compared to Example 1, in step one of this example, carbon nanotubes are replaced with an equal weight of molybdenum disulfide. The remaining steps are the same as in Example 1.

[0099] Comparative Example 1

[0100] Compared to Example 1, no conventional nanocellulose was added in step two. The remaining steps were the same as in Example 1.

[0101] Comparative Example 2

[0102] Compared to Example 1, step two does not involve the addition of conventional nanocellulose or nanocellulose composite materials. The remaining steps are the same as in Example 1.

[0103] Comparative Example 3

[0104] Compared to Example 1, step two) did not involve the addition of nanocellulose composite material. The remaining steps were the same as in Example 1. Microscopic images of the carbonized aluminum foil coating of this comparative example after baking are shown below. Figure 2 As shown, compared with Example 1, the surface of this comparative example lacks the traces and patterns left by the decomposition and curling of cellulose formed in Example 1, and has a lower surface roughness, which will result in insufficient adhesion after rolling.

[0105] Test example:

[0106] The cathode material was coated onto the carbon coating layer of each embodiment and comparative example, and then passed through an oven at a temperature set to the solvent temperature of the nanocellulose composite material. The oven temperature was set to 120°C, the oven length needed to be greater than 10m, and the heating time was 7min. After baking, the nanocellulose in the coating was decomposed and volatilized. The cathode was then formed by roll pressing, with a compaction density of 2.35g / cm³. 2 .

[0107] After preparation, the electrode peel force and tensile strength of each embodiment and comparative sample were tested. The electrode peel force test method was as follows: the rolled electrode was cut into 10 x 2 cm pieces. An electronic peel tester was used. The cut electrode sample was attached to the stainless steel test plate using 2 cm wide 3M tape, and one side of the electrode was peeled off to perform a 180° electrode peel test. After the test, the experimental parameters were recorded.

[0108] Tensile strength test method: The experiment was conducted using a Tesla universal tensile testing machine. Carbon-coated foil was cut into 15 x 1.5 cm strips, which were then clamped onto the machine. The tensile speed was 100 mm / min. The experimental data were recorded after the test. The test results are shown in Table 1.

[0109] Table 1 Test Results

[0110]

[0111] Based on the performance comparison of the above embodiments and comparative examples, it can be seen that the added nanocellulose composite material will decompose and volatilize after baking, which can significantly increase the roughness of the coating. After the positive electrode active material and the coating are rolled together, the interlocking force between the two will be greatly increased. The comparative electrode without the addition of nanocellulose composite material has a lower peeling force.

[0112] Adding conventional nanocellulose can significantly improve the toughness of aluminum foil, while the tensile strength of the comparative sample without nanocellulose is significantly lower.

[0113] The above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a battery positive electrode, characterized by, The method comprises the following steps: The positive electrode material is coated on the carbon-coated layer of the carbon-coated aluminum foil with high adhesion, then is pressed and heated to decompose and volatilize the nanocellulose in the nanocellulose composite in the carbon-coated layer; The carbon-coated aluminum foil with high adhesion comprises a carbon-coated layer containing a carbon conductive agent, nanocellulose and a nanocellulose composite formed by compounding raw materials containing nanocellulose and a thermally and electrically conductive nanomaterial; The compounding of the nanocellulose and the thermally and electrically conductive nanomaterial comprises the following steps: mixing the nanocellulose and the thermally and electrically conductive nanomaterial and then grinding; and then ultrasonic treating the grinded mixture in a solvent to obtain the nanocellulose composite; The nanocellulose in the nanocellulose composite can be decomposed and volatilized after baking; The weight of the nanocellulose is 5-15% of the weight of the carbon conductive agent; The weight ratio of the nanocellulose to the nanocellulose composite is 1:0.2-0.67; The thermally and electrically conductive nanomaterial is carbon nanotube; and the weight ratio of the nanocellulose to the carbon nanotube in the nanocellulose composite is 1:1.5-5.

2. The production method according to claim 1, characterized by, The carbon conductive agent comprises carbon powder; or the carbon conductive agent comprises carbon powder and graphite powder, and the weight ratio of the carbon powder to the graphite powder is 7-9:1-3.

3. The production method according to claim 1, characterized by, The preparation method of the carbon-coated aluminum foil with high adhesion comprises the following steps: Step one) compounding the nanocellulose and the thermally and electrically conductive nanomaterial to obtain a nanocellulose composite; Step two) uniformly mixing raw materials containing the nanocellulose composite, nanocellulose and a carbon conductive agent to obtain carbon-coated slurry; Step three) coating the carbon-coated slurry on an aluminum foil to form a carbon-coated layer, thereby obtaining the carbon-coated aluminum foil.

4. The production method according to claim 1, characterized by, The nanocellulose is prepared by an acid treatment method using plant cellulose as raw material.

5. The preparation method according to claim 1, characterized in that, The diameter of the carbon nanotube is 1-5 nm, and the length of the carbon nanotube is 40-120 nm; and / or The nanocellulose and the carbon nanotube are mixed at 800-1200 r / min and ball-milled for 40-80 min, and the size of the ball-milling zirconium beads is 0.05-0.5 mm; then the grinded mixture is ultrasonic treated in a solvent for 90-150 min, and the ultrasonic frequency is 2000-4500 Hz, thereby obtaining the nanocellulose composite.

6. The preparation method according to claim 3, characterized in that, The raw materials in step two) further comprise a binder; and / or The way of uniformly mixing the raw materials containing the nanocellulose composite, nanocellulose and a carbon conductive agent in step two) comprises the following steps: Step a) uniformly mixing the binder and a part of the carbon conductive agent to obtain a mixture I; then adding the nanocellulose into the mixture I to obtain a mixture II; Step b) adding the remaining carbon conductive agent into the mixture II to obtain a mixture III, and then adding the nanocellulose composite into the mixture III to obtain a mixture IV; Step c) adjusting the pH of the mixture IV to 5-7 to obtain the carbon-coated slurry; and / or The binder uses at least one of acrylate, polyacrylic acid, modified polyacrylic acid, water-based polyurethane; and / or In step a), the binder is diluted with water, and then mixed with a part of the carbon conductive agent to obtain a mixture I.

7. The production method according to claim 6, characterized by, In step two), it further includes: d) adding a wetting agent to the carbon coating slurry and mixing uniformly, wherein the wetting agent comprises at least one of polyether siloxane, modified polyether siloxane, and alcohol wetting agent; and / or The addition amount of the wetting agent is 5-10% of the mass of the carbon coating slurry; and / or In step two), it further includes: homogenizing the carbon coating slurry.

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