A battery aluminum foil and a method for manufacturing the same

Abstract

The application provides a battery aluminum foil and a preparation method thereof, and relates to the technical field of battery aluminum foils.The preparation method is as follows: S1, hot rolling of an aluminum foil blank to obtain an aluminum foil intermediate body with a thickness of 3.5-4.1 mm; S2, multi-pass cold rolling of the aluminum foil intermediate body under ultrasonic vibration system using lubricating oil to obtain a foil rolling blank with a thickness of 0.35-0.45 mm, wherein, when the cold rolling is rolled to an intermediate pass thickness of 0.6-0.9 mm, complete recrystallization annealing is carried out under nitrogen protection, and the annealing temperature is 400-450 DEG C; S3, foil rolling of the foil rolling blank to obtain an aluminum foil with a thickness of 0.01-0.015 mm; and S4, corona treatment of the aluminum foil, coating of modified paint on the surface of the aluminum foil, drying, and obtaining of the battery aluminum foil.The battery aluminum foil has excellent electrochemical performance, high strength, and high surface roughness.

Description

Technical Field

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

[0002] Developing new energy vehicles is an important measure to address climate change and promote green development. Currently, new energy vehicles are more energy-efficient and pollution-free than traditional gasoline-powered vehicles. In particular, pure electric vehicles powered by batteries have received unanimous praise from users.

[0003] The power source for electric vehicles is primarily lithium-ion batteries, which are mobile energy sources composed of an anode, a cathode, and an electrolyte. The positive electrode requires aluminum foil, and the quality of the aluminum foil directly affects the battery's performance and lifespan.

[0004] Existing battery aluminum foils suffer from poor electrochemical performance, low strength, and poor surface quality, failing to meet the requirements of power batteries. Therefore, it is necessary to provide a method for preparing battery aluminum foil and a suitable battery aluminum foil to address these issues. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing battery aluminum foil, which has excellent electrochemical properties, high strength, and high surface roughness.

[0006] Another objective of this invention is to provide a battery aluminum foil that can meet the requirements of power batteries for battery aluminum foil, thereby improving battery performance and extending battery life.

[0007] The embodiments of the present invention are achieved through the following technical solutions: A method for preparing battery aluminum foil includes the following steps: S1. The aluminum foil blank is hot-rolled to obtain an aluminum foil intermediate with a thickness of 3.5-4.1 mm, wherein the hot-rolling temperature is 300-330℃; S2. The aluminum foil intermediate is cold rolled in multiple passes using lubricating oil under an ultrasonic vibration system at a vibration frequency of 35-40kHz to obtain a foil blank with a thickness of 0.35-0.45mm. When the thickness of the intermediate pass is 0.6-0.9mm after cold rolling, it is fully recrystallized and annealed under nitrogen protection at a temperature of 400-450℃. S3. The foil blank is subjected to foil rolling to obtain an aluminum foil with a thickness of 0.01-0.015 mm, wherein the foil rolling speed is 400-600 m / min; S4. The aluminum foil is subjected to corona treatment, and then a modified coating is applied to the surface of the aluminum foil. It is then vacuum dried at a temperature of 75-85℃ for 1-2 hours, and then the temperature is raised to 130-150℃ for 2-3 hours.

[0008] A battery aluminum foil, made by the above-described method for preparing battery aluminum foil.

[0009] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects: In this invention, the aluminum foil blank is hot-rolled at 300-330℃. Under pressure, the blank's microstructure is adjusted, resulting in a more uniform structure, smaller grains, and improved mechanical properties, especially tensile strength and plasticity. It also increases the material's hardness and toughness, providing good wear and corrosion resistance. The surface strength is reduced, decreasing processing quantity and time, thus lowering processing costs. Surface gloss is also improved. The use of lubricating oil prevents aluminum adhesion and surface damage. Cold rolling under ultrasonic vibration conditions optimizes aluminum foil quality through microscopic control. Specifically, it improves the reaction between metallic and non-metallic phases, promotes nanocrystallization, reduces surface energy, and thus obtains smaller particle sizes, improving the aluminum foil's processing and mechanical properties. Multiple cold rolling processes deform and thin the aluminum foil while increasing its surface smoothness, resulting in a uniform thickness and smooth edges. Full recrystallization annealing at 400-450℃ under nitrogen protection eliminates the deformation strengthening effect of aluminum foil, restoring it to a more flexible state, facilitating subsequent processing, improving its formability and processing performance, reducing the risk of breakage and cracking, and increasing product yield and quality. Foil rolling allows for further thinning of the aluminum foil to achieve predetermined thickness and width.

[0010] Aluminum foil surfaces can be modified by combining corona treatment, modified coatings, and baking, increasing surface roughness and enhancing electrode adhesion. The modified coating, filling the space between the active material and the aluminum foil, increases the contact area between the positive electrode active material and the current collector, reducing interfacial resistance and improving battery internal resistance consistency. Furthermore, it enhances internal current conduction, improves the rate performance of lithium batteries, provides good heat dissipation, reduces the impact of high temperatures on the active material, and offers a certain shielding effect against corrosive media, improving corrosion resistance. Vacuum drying at 75-85℃ for 1-2 hours, followed by drying at 130-150℃ for 2-3 hours, can improve the adhesion of the modified coating to the aluminum foil surface. Detailed Implementation

[0011] 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.

[0012] A method for preparing battery aluminum foil includes the following steps: S1. The aluminum foil blank is hot-rolled to obtain an aluminum foil intermediate with a thickness of 3.5-4.1mm. The hot-rolling temperature is 300-330℃. When the aluminum foil blank is hot-rolled at 300-330℃, the blank is subjected to pressure, and its microstructure will be adjusted, making the microstructure more uniform, the grains smaller, and improving the mechanical properties, especially tensile strength and plasticity. It can also improve the hardness and toughness of the material, and has good wear resistance and corrosion resistance. It reduces the surface strength of the material, reduces the amount of processing and time, and lowers the processing cost. It also improves the surface gloss.

[0013] S2. The aluminum foil intermediate is cold-rolled multiple times under an ultrasonic vibration system using lubricating oil. The vibration frequency is 35-40kHz, resulting in a foil blank with a thickness of 0.35-0.45mm. When the thickness reaches 0.6-0.9mm in the intermediate passes, it undergoes complete recrystallization annealing under nitrogen protection at a temperature of 400-450℃. The use of lubricating oil prevents aluminum adhesion and surface damage. Cold rolling under ultrasonic vibration conditions allows for microscopic control to optimize aluminum foil quality. Specifically, it improves the reaction between the metallic and non-metallic phases, promotes nanocrystallization, reduces surface energy, resulting in smaller particle sizes and improved processing and mechanical properties of the aluminum foil. Multiple cold rolling processes deform and thin the aluminum foil, while increasing its surface smoothness, resulting in a uniform thickness and smooth edges. Complete recrystallization annealing at 400-450℃ under nitrogen protection can eliminate the deformation strengthening effect of aluminum foil, restore the aluminum foil to a relatively soft state, facilitate subsequent processing, improve the formability and processing performance of aluminum foil, reduce the risk of breakage and cracking, and improve the yield and quality of products.

[0014] S3. The foil blank is subjected to foil rolling to obtain an aluminum foil with a thickness of 0.01-0.015 mm, wherein the rolling speed of the foil rolling is 400-600 m / min; foil rolling can further thin the aluminum foil to achieve a predetermined thickness and width.

[0015] S4. The aluminum foil is subjected to corona treatment, and then a modified coating is applied to the surface of the aluminum foil. It is then vacuum dried at a temperature of 75-85℃ for 1-2 hours, and then the temperature is raised to 130-150℃ for 2-3 hours.

[0016] By combining corona treatment, modified coating, and baking, the surface of aluminum foil can be modified, increasing its surface roughness and enhancing electrode adhesion. The modified coating, filling the space between the active material and the aluminum foil, increases the contact area between the positive electrode active material and the current collector, reducing interfacial resistance and improving the consistency of battery internal resistance. Furthermore, it enhances internal current conduction, improves the rate performance of lithium batteries, provides good heat dissipation, reduces the impact of high temperatures on the active material, and offers a certain shielding effect against corrosive media, improving corrosion resistance. Drying at specific temperatures further enhances the adhesion of the modified coating to the aluminum foil surface.

[0017] Furthermore, the lubricating oil includes a base oil and lauric acid, wherein the mass of the lauric acid is 10-12% of the mass of the base oil. As an additive, lauric acid can enhance the lubrication effect of the base oil during the cold rolling process of the aluminum foil intermediate, prevent the aluminum foil intermediate from sticking together, and prevent damage to the surface of the aluminum foil intermediate during the cold rolling process.

[0018] Furthermore, in step S4, the corona power is 10kW and the speed is 100m / min. The corona treatment can modify the surface of the aluminum foil, enhance the adhesion between the aluminum foil and the active material, and increase the contact area between the aluminum foil and the active material.

[0019] Furthermore, the modified coating comprises, by weight, 5-15 parts graphene oxide, 5-10 parts nano carbon black, 20-60 parts alkylamine, 10-20 parts maleic anhydride-grafted polypropylene, and 100-200 parts sodium carboxymethyl cellulose.

[0020] Graphene possesses advantages such as large specific surface area, good conductivity, and light weight, along with thinness and strong adhesion, making it highly effective in improving the performance of lithium-ion batteries. Coating with graphene nanosheets not only increases the contact area between the electrode material and aluminum foil but also enhances their adhesion, facilitating electrical contact and charge transport, and inhibiting aluminum foil corrosion during long-term cycling. However, excessive graphene nanosheet coverage can reduce battery performance due to increased interlayer contact. Combining carbon black nanoparticles with graphene to form a co-conductive network effectively compensates for the low interlayer conductivity of graphene nanosheets.

[0021] Because graphene oxide contains a large number of active oxygen-containing functional groups (hydroxyl, carboxyl, and epoxy groups) on its surface and edges, it exhibits good compatibility with water and certain organic solvents. However, it also possesses a high specific surface area and strong van der Waals forces, making it prone to agglomeration in some weakly polar polymers, thus affecting its performance. Therefore, alkylamines are selected as modifiers to combine with graphene oxide. Through the intercalation of long-chain alkanes, the interlayer spacing of graphene oxide is increased, effectively preventing stacking, aggregation, and agglomeration, thereby improving its compatibility with weakly polar matrices. The active oxygen-containing functional groups of graphene oxide serve as grafting sites, reacting chemically with compounds rich in active groups to form covalent bonds.

[0022] Maleic anhydride-grafted polypropylene, used as an adhesive, enhances the adhesion of graphene oxide and nano-carbon black to aluminum foil surfaces. Sodium carboxymethyl cellulose, as an aqueous solvent, allows for direct blending of the raw materials before coating onto the aluminum foil surface, a simple and convenient process. Furthermore, maleic anhydride-grafted polypropylene can also be grafted and composited with graphene oxide to improve the barrier properties of the material.

[0023] The graphene oxide matrix helps increase the loading and dispersibility of the modified material, thereby improving its performance. The embedding of carbon black nanoparticles into the graphene oxide matrix endows the modified material with ion exchange capabilities, enabling applications in water treatment and ion separation. Due to the conductivity of graphene oxide and the electrochemical activity of carbon black nanoparticles, it can be used as an electrochemical electrode material in supercapacitors and lithium-ion batteries. The combination of graphene oxide and carbon black nanoparticles can enhance catalytic activity and selectivity, exhibiting strong adsorption properties.

[0024] By coating aluminum foil with a modified coating to form a cover layer, the contact area between the electrode material and the aluminum foil is increased. It also acts as a buffer layer, enhancing adhesion between the two and effectively reducing resistance, thus suppressing the increase in resistance during charging and discharging. Furthermore, it prevents corrosion of the aluminum foil, improving the overall performance of the lithium-ion battery, such as higher charge-discharge rate performance, better safety, and longer cycle life.

[0025] Furthermore, the preparation method of the modified coating is as follows: graphene oxide is prepared into a dispersion using an organic solvent, alkylamine is added, stirred, sonicated for 1 hour, reacted at 100-120℃ for 20 hours, centrifuged, washed with ethanol until neutral, and dried to obtain material A; sodium carboxymethyl cellulose is prepared into a solution, maleic anhydride-grafted polypropylene is added, sonicated for 1-2 hours, and then material A and nano carbon black are added, and sonicated for 2-4 hours.

[0026] When preparing a dispersion of graphene oxide: graphene oxide and an organic solvent are mixed and sonicated at room temperature for 0.5 hours to obtain a uniformly dispersed graphene oxide dispersion. By blending graphene oxide aerogel with alkylamines and then sonicating, graphene oxide can be modified to possess abundant hydrophobic alkane chains and a special sheet-like structure similar to graphene. This provides a certain shielding effect against corrosive media and adhesion to metal substrates, resulting in superior coating performance.

[0027] Furthermore, the preparation method of graphene oxide is as follows: natural graphene powder is mixed with concentrated sulfuric acid, sodium pernitrate and potassium permanganate are added, and the mixture is reacted at 0℃ for 1-3 hours, then heated to 30-35℃ for 2-4 hours, and further heated to 60℃ for 1 hour. Hydrogen peroxide is added and the mixture is allowed to stand for 12 hours. After filtration, the mixture is washed with distilled water until neutral to obtain a graphene oxide slurry. This slurry is then rapidly frozen with liquid nitrogen and placed in a freeze dryer for 2 days to obtain a graphene oxide aerogel. The liquid nitrogen freezing temperature is -196℃, and the freeze dryer temperature is 55℃. This method can increase the number of active functional groups on graphene oxide, increase the number of active modification grafting sites, and improve the modification effect of graphene oxide.

[0028] Furthermore, the organic solvent is N,N-dimethylformamide or N-methylpyrrolidone. The ratio of organic solvent to graphene oxide is (10-15) ml : (0.05-0.1) g. In the above organic solvent, the graphene oxide is dispersed more uniformly.

[0029] Furthermore, alkylamines include one or more of dodecylamine, hexadecylamine, and octadecylamine.

[0030] The battery aluminum foil of this application exhibits significantly enhanced electrochemical performance in terms of internal resistance, specific capacity, rate performance, and cycle stability.

[0031] Example 1 A method for preparing battery aluminum foil includes the following steps: S1. The aluminum foil blank is hot-rolled to obtain an aluminum foil intermediate with a thickness of 3.5 mm, wherein the hot-rolling temperature is 300℃; S2. The aluminum foil intermediate is cold rolled in multiple passes using lubricating oil under an ultrasonic vibration system at a vibration frequency of 35kHz to obtain a foil blank with a thickness of 0.35mm. When the thickness of the intermediate pass is 0.6mm after cold rolling, it is fully recrystallized and annealed under nitrogen protection at a temperature of 400℃. S3. The foil blank is subjected to foil rolling to obtain an aluminum foil with a thickness of 0.01 mm, wherein the foil rolling speed is 400 m / min; S4. The aluminum foil is subjected to corona treatment with a power of 10kW and a speed of 100m / min. Then, a modified coating is applied to the surface of the aluminum foil, and it is vacuum dried at a temperature of 75℃ for 1 hour, followed by drying at 130℃ for 2 hours.

[0032] The modified coating includes: 5g of graphene oxide, 5g of nano carbon black, 20g of dodecylamine, 10g of maleic anhydride-grafted polypropylene, and 100g of sodium carboxymethyl cellulose. The modified coating is prepared as follows: graphene oxide and N,N-dimethylformamide are mixed and sonicated at room temperature for 0.5 h to obtain a uniformly dispersed graphene oxide dispersion. Dodecylamine is added, stirred, sonicated for 1 h, reacted at 100℃ for 20 h, centrifuged, washed with ethanol until neutral, and dried to obtain material A; sodium carboxymethyl cellulose is prepared into a solution, maleic anhydride-grafted polypropylene is added, sonicated for 1 h, and then material A and nano carbon black are added and sonicated for 2 h. The preparation method of graphene oxide is as follows: natural graphene powder is mixed with concentrated sulfuric acid, sodium pernitrate and potassium permanganate are added, and the mixture is reacted at 0℃ for 1 h, heated to 30℃ for 2 h, and then heated to 60℃ for 1 h. Hydrogen peroxide is added and the mixture is allowed to stand for 12 h. The mixture is filtered, washed with distilled water until neutral, and graphene oxide slurry is obtained. The slurry is then rapidly frozen with liquid nitrogen (-196℃) and placed in a freeze dryer (55℃) for 2 days to obtain graphene oxide aerogel.

[0033] Example 2 A method for preparing battery aluminum foil includes the following steps: S1. The aluminum foil blank is hot-rolled to obtain an aluminum foil intermediate with a thickness of 3.6 mm, wherein the hot-rolling temperature is 310℃; S2. The aluminum foil intermediate is cold rolled in multiple passes using lubricating oil under an ultrasonic vibration system at a vibration frequency of 36kHz to obtain a foil blank with a thickness of 0.38mm. When the thickness of the intermediate pass is 0.7mm after cold rolling, it is fully recrystallized and annealed under nitrogen protection at a temperature of 410℃. S3. The foil blank is subjected to foil rolling to obtain an aluminum foil with a thickness of 0.012 mm, wherein the foil rolling speed is 450 m / min; S4. The aluminum foil is subjected to corona treatment with a power of 10kW and a speed of 100m / min. Then, a modified coating is applied to the surface of the aluminum foil, and it is vacuum dried at a temperature of 78℃ for 1.2h, followed by drying at 135℃ for 2.2h.

[0034] The modified coating includes: 8g of graphene oxide, 6g of nano carbon black, 25g of dodecylamine, 12g of maleic anhydride-grafted polypropylene, and 120g of sodium carboxymethyl cellulose. The modified coating is prepared as follows: graphene oxide and N-methylpyrrolidone are mixed and sonicated at room temperature for 0.5 h to obtain a uniformly dispersed graphene oxide dispersion. Dodecylamine is added, stirred, sonicated for 1 h, reacted at 105℃ for 20 h, centrifuged, washed with ethanol until neutral, and dried to obtain material A; sodium carboxymethyl cellulose is prepared into a solution, maleic anhydride-grafted polypropylene is added, sonicated for 1.2 h, and then material A and nano carbon black are added and sonicated for 2.5 h. The preparation method of graphene oxide is as follows: natural graphene powder is mixed with concentrated sulfuric acid, sodium pernitrate and potassium permanganate are added, and the mixture is reacted at 0℃ for 1.2h, heated to 33℃ for 2.5h, and then heated to 60℃ for 1h. Hydrogen peroxide is added and the mixture is allowed to stand for 12h. The mixture is filtered, washed with distilled water until neutral, and graphene oxide slurry is obtained. After being rapidly frozen with liquid nitrogen (-196℃), the slurry is placed in a freeze dryer (55℃) and frozen for 2d to obtain graphene oxide aerogel.

[0035] Example 3 A method for preparing battery aluminum foil includes the following steps: S1. The aluminum foil blank is hot-rolled to obtain an aluminum foil intermediate with a thickness of 4mm, wherein the hot-rolling temperature is 320℃; S2. The aluminum foil intermediate is cold rolled in multiple passes using lubricating oil under an ultrasonic vibration system at a vibration frequency of 38kHz to obtain a foil blank with a thickness of 0.4mm. When the thickness of the intermediate pass is 0.8mm after cold rolling, it is fully recrystallized and annealed under nitrogen protection at a temperature of 440℃. S3. The foil blank is subjected to foil rolling to obtain an aluminum foil with a thickness of 0.014 mm, wherein the foil rolling speed is 500 m / min; S4. The aluminum foil is subjected to corona treatment with a power of 10kW and a speed of 100m / min. Then, a modified coating is applied to the surface of the aluminum foil, and it is vacuum dried at a temperature of 80℃ for 1.8h. After that, the temperature is raised to 145℃ and dried for 2.5h.

[0036] The modified coating includes: 12g of graphene oxide, 8g of nano carbon black, 50g of hexadecylamine, 15g of maleic anhydride-grafted polypropylene, and 180g of sodium carboxymethyl cellulose. The modified coating is prepared as follows: graphene oxide and N,N-dimethylformamide are mixed and sonicated at room temperature for 0.5 h to obtain a uniformly dispersed graphene oxide dispersion. Hexadecylamine is added, stirred, sonicated for 1 h, reacted at 115℃ for 20 h, centrifuged, washed with ethanol until neutral, and dried to obtain material A; sodium carboxymethyl cellulose is prepared into a solution, maleic anhydride-grafted polypropylene is added, sonicated for 1.8 h, and then material A and nano carbon black are added and sonicated for 3 h. The preparation method of graphene oxide is as follows: natural graphene powder is mixed with concentrated sulfuric acid, sodium pernitrate and potassium permanganate are added, and the mixture is reacted at 0℃ for 2 hours, heated to 33℃ for 3 hours, and then heated to 60℃ for 1 hour. Hydrogen peroxide is added and the mixture is allowed to stand for 12 hours. The mixture is filtered, washed with distilled water until neutral, and graphene oxide slurry is obtained. The slurry is then rapidly frozen with liquid nitrogen (-196℃) and placed in a freeze dryer (55℃) for 2 days to obtain graphene oxide aerogel.

[0037] Example 4 A method for preparing battery aluminum foil includes the following steps: S1. The aluminum foil blank is hot-rolled to obtain an aluminum foil intermediate with a thickness of 4.1 mm. The hot-rolling temperature is 330°C. S2. The aluminum foil intermediate is cold rolled in multiple passes using lubricating oil under an ultrasonic vibration system at a vibration frequency of 40kHz to obtain a foil blank with a thickness of 0.45mm. When the thickness of the intermediate pass is 0.9mm after cold rolling, it is fully recrystallized and annealed under nitrogen protection at a temperature of 450℃. S3. The foil blank is subjected to foil rolling to obtain an aluminum foil with a thickness of 0.015 mm, wherein the foil rolling speed is 600 m / min; S4. The aluminum foil is subjected to corona treatment with a power of 10kW and a speed of 100m / min. Then, a modified coating is applied to the surface of the aluminum foil, and it is vacuum dried at a temperature of 85℃ for 2 hours, followed by drying at 150℃ for 3 hours.

[0038] The modified coating includes: 15g of graphene oxide, 10g of nano carbon black, 60g of octadecylamine, 20g of maleic anhydride-grafted polypropylene, and 200g of sodium carboxymethyl cellulose. The modified coating is prepared as follows: graphene oxide and N-methylpyrrolidone are mixed and sonicated at room temperature for 0.5 h to obtain a uniformly dispersed graphene oxide dispersion. Octadecylamine is added, stirred, sonicated for 1 h, reacted at 120℃ for 20 h, centrifuged, washed with ethanol until neutral, and dried to obtain material A; sodium carboxymethyl cellulose is prepared into a solution, maleic anhydride-grafted polypropylene is added, sonicated for 2 h, and then material A and nano carbon black are added and sonicated for 4 h. The preparation method of graphene oxide is as follows: natural graphene powder is mixed with concentrated sulfuric acid, sodium pernitrate and potassium permanganate are added, and the mixture is reacted at 0℃ for 3 hours, heated to 35℃ for 4 hours, and then heated to 60℃ for 1 hour. Hydrogen peroxide is added and the mixture is allowed to stand for 12 hours. The mixture is filtered, washed with distilled water until neutral, and graphene oxide slurry is obtained. The slurry is then rapidly frozen with liquid nitrogen (-196℃) and placed in a freeze dryer (55℃) for 2 days to obtain graphene oxide aerogel.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that no modified coating was applied; in this case, the aluminum foil surface was modified by corona discharge and baking.

[0040] Comparative Example 2 The difference between this comparative example and Example 1 is that no corona treatment was performed.

[0041] Comparative Example 3 The difference between this comparative example and Example 1 is that the graphene oxide in the modified coating is replaced with natural graphene.

[0042] Comparative Example 4 The difference between this comparative example and Example 1 is that no nano-carbon black is added to the modified coating.

[0043] Comparative Example 5 The difference between this comparative example and Example 1 is that no graphene oxide is added to the modified coating.

[0044] Comparative Example 6 The difference between this comparative example and Example 1 is that the graphene oxide is not modified; instead, the raw materials of the modified coating are directly mixed and then subjected to ultrasonic treatment.

[0045] Comparative Example 7 The difference between this comparative example and Example 1 is that ultrasonic vibration is not used in the cold rolling process.

[0046] Test results The battery aluminum foils prepared in the examples and comparative examples were tested, and the results are as follows: Roughness: The surface roughness of the battery aluminum foil was tested using a Mitutoyo SJ-210 roughness tester from Japan.

[0047] Electrode adhesion: The adhesion between the active coating of the electrode and the aluminum foil was tested using a Dongguan Lixian HZ-1007C tensile testing machine. Test method: Electrode strips with a length of 250 mm and a width of 180 mm were prepared. The electrode coating was adhered to the strips using 3M tape, and the strips were peeled off at 180° for a distance of 100 m.

[0048] Battery internal resistance: The AC internal resistance (ACR) of the battery at 30% SOC was tested using a Changzhou Hepu Electronics HP3554 battery internal resistance tester.

[0049] The corrosion resistance, tensile strength and total elongation at break of aluminum foil were tested in accordance with GB / T 3198-2010 "Aluminum Foil".

[0050] Table 1 Performance Testing

[0051] As shown in Table 1, the battery aluminum foils prepared in Examples 1-4 have high surface roughness, large electrode adhesion, low battery internal resistance, good tensile strength, total elongation at break, and corrosion resistance.

[0052] Compared to Example 1, Comparative Example 1 showed poorer surface roughness, electrode adhesion, total elongation at break, and corrosion resistance. This indicates that the modified coating can enhance the surface properties of the aluminum foil. Compared to Example 1, Comparative Example 2 showed poorer surface roughness and electrode adhesion. This indicates that corona treatment can enhance the surface roughness of the aluminum foil and electrode adhesion. Comparative Examples 1-2, compared to the examples, show that the combination of corona treatment and modified coating can enhance the surface roughness of the aluminum foil and electrode adhesion.

[0053] Compared with Example 1, Comparative Example 3 showed poorer electrode adhesion, battery internal resistance, and corrosion resistance. This indicates that graphene oxide can enhance electrode adhesion, reduce battery internal resistance, and improve corrosion resistance. The reason may be that graphene oxide has a large number of active functional groups, which can form a network structure with alkylamines and maleic anhydride-grafted polypropylene, enabling it to load more nano-carbon black and facilitate the formation of a stable separator film on the aluminum foil surface.

[0054] Comparative Examples 4-5, compared to Example 1, show that the combination of nano-carbon black and graphene oxide can reduce the internal resistance of the battery and improve the corrosion resistance of the aluminum foil. Comparative Example 6, compared to Example 1, shows that the preparation method used in the examples can enhance the modification effect of the modified coating on the aluminum foil, resulting in superior aluminum foil performance. Comparative Example 7, compared to Example 1, shows that using ultrasonic vibration-assisted rolling can enhance the mechanical properties of the aluminum foil.

[0055] In summary, this application provides a battery aluminum foil with high surface roughness, large electrode adhesion, low battery internal resistance, and good tensile strength, total elongation at break, and corrosion resistance.

[0056] 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. A method for preparing battery aluminum foil, characterized in that, Includes the following steps: S1. The aluminum foil blank is hot-rolled to obtain an aluminum foil intermediate with a thickness of 3.5-4.1 mm, wherein the hot-rolling temperature is 300-330℃; S2. The aluminum foil intermediate is cold rolled in multiple passes using lubricating oil under an ultrasonic vibration system at a vibration frequency of 35-40kHz to obtain a foil blank with a thickness of 0.35-0.45mm. When the thickness of the intermediate pass is 0.6-0.9mm after cold rolling, it is fully recrystallized and annealed under nitrogen protection at a temperature of 400-450℃. S3. The foil blank is subjected to foil rolling to obtain an aluminum foil with a thickness of 0.01-0.015 mm, wherein the foil rolling speed is 400-600 m / min; S4. The aluminum foil is subjected to corona treatment, and then a modified coating is applied to the surface of the aluminum foil. It is then vacuum dried at a temperature of 75-85℃ for 1-2 hours, and then heated to 130-150℃ for 2-3 hours to obtain the battery aluminum foil. The modified coating comprises, by weight, 5-15 parts graphene oxide, 5-10 parts nano carbon black, 20-60 parts alkylamine, 10-20 parts maleic anhydride-grafted polypropylene, and 100-200 parts sodium carboxymethyl cellulose.

2. The method for preparing battery aluminum foil according to claim 1, characterized in that, The lubricating oil comprises a base oil and lauric acid, wherein the mass of the lauric acid is 10-12% of the mass of the base oil.

3. The method for preparing battery aluminum foil according to claim 1, characterized in that, In step S4, the corona power is 10kW and the speed is 100m / min.

4. The method for preparing battery aluminum foil according to claim 1, characterized in that, The modified coating is prepared as follows: graphene oxide is prepared into a dispersion using an organic solvent, alkylamine is added, stirred, sonicated for 1 hour, reacted at 100-120℃ for 20 hours, centrifuged, washed with ethanol until neutral, and dried to obtain material A; sodium carboxymethyl cellulose is prepared into a solution, maleic anhydride-grafted polypropylene is added, sonicated for 1-2 hours, and then material A and nano carbon black are added, and sonicated for 2-4 hours.

5. The method for preparing battery aluminum foil according to claim 1, characterized in that, The preparation method of the graphene oxide is as follows: natural graphene powder is mixed with concentrated sulfuric acid, sodium pernitrate and potassium permanganate are added, and the mixture is reacted at 0℃ for 1-3 hours, heated to 30-35℃ for 2-4 hours, and then heated to 60℃ for 1 hour. Hydrogen peroxide is added and the mixture is allowed to stand for 12 hours. The mixture is then filtered, washed with distilled water until neutral, and graphene oxide slurry is obtained. After being rapidly frozen with liquid nitrogen, the slurry is placed in a freeze dryer and frozen for 2 days to obtain graphene oxide aerogel.

6. The method for preparing battery aluminum foil according to claim 4, characterized in that, The organic solvent is N,N-dimethylformamide or N-methylpyrrolidone.

7. The method for preparing battery aluminum foil according to claim 1, characterized in that, The alkylamines include one or more of dodecylamine, hexadecylamine, and octadecylamine.

8. A battery aluminum foil, characterized in that, It is made by the method of preparing battery aluminum foil according to any one of claims 1-7.

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