Antioxidant lithium battery copper foil and preparation method thereof

Abstract

The invention discloses an antioxidant lithium battery copper foil and a preparation method thereof, and relates to the technical field of current collector preparation. The anti-oxidation liquid has a corrosion inhibition effect on copper, mercaptobenzothiazole and sodium molybdate can be in bridge connection with metal copper ions through chemical bonds and can be adsorbed on the surface of a metal copper layer, a compact and uniform organic protective film is formed on the copper surface under the participation of triethanolamine, the permeability of oxygen or water can be reduced, the copper surface can be effectively prevented from being oxidized, and the corrosion resistance of the copper surface is improved. The anti-oxidation liquid does not contain zinc ions or chromium and other elements, so that the performance and safety requirements of high-end lithium battery manufacturers can be met; the anti-oxidation liquid in the invention is colorless, does not need to be squeezed by an extrusion roller for cleaning, can be directly washed by water, has no liquid medicine residue on the surface of the foil, can effectively improve the abnormal appearance such as floating and whitening of the composite copper foil, has no different color on the film surface after high-temperature baking, can effectively improve the product quality and the product performance, and further improves the stability of the composite current collector; the service life and the safety performance of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of current collector preparation technology, specifically an antioxidant lithium battery copper foil and its preparation method. Background Technology

[0002] The rapid development of new energy and electronic technologies has made battery cycle life, safety performance, and energy density paramount. The current collector, which gathers the current generated by the battery's active materials to form a larger current output, is a crucial component of the battery, and its performance directly affects the battery's cycle life, safety performance, and energy density.

[0003] In current technologies, copper and aluminum foils are mostly used as current collectors for the positive and negative electrodes in lithium-ion and sodium-ion batteries. While these materials offer high quality, they are also expensive, which is detrimental to controlling battery costs and improving energy density. Therefore, composite foils offer significant advantages over traditional foils. Composite foil current collectors typically have a sandwich structure, with a polymer layer on the inner layer and metal conductive layers on both sides. Because the surface metal layer is thinner and the inner polymer layer is lighter, the overall weight of the current collector can be significantly reduced, increasing the energy density of the lithium-ion battery. Furthermore, the metal layer is more likely to break during thermal runaway in lithium-ion batteries compared to traditional foil current collectors, isolating the active material from the current collector and preventing thermal runaway.

[0004] Although composite foils have the advantages of low cost and light weight, most composite copper foils currently use electroplating to thicken the copper layer. After the electroplating layer meets customer requirements, it is treated with antioxidant chemical solutions. However, most of the chemicals on the market contain zinc ions or chromium and other elements, which have weak antioxidant capacity. They must be squeezed out and cleaned by extrusion rollers, which can easily cause chemical residues, contaminating the composite copper foil. This often results in abnormal appearances such as foil discoloration and whitening. After high-temperature baking, the film surface becomes discolored, affecting product performance and also posing safety issues to the battery.

[0005] Therefore, we propose an antioxidant lithium-ion battery copper foil and its preparation method, which enables the composite foil current collector to have good antioxidant and conductive effects. Summary of the Invention

[0006] The purpose of this invention is to provide an antioxidant lithium battery copper foil and its preparation method to solve the problems raised in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing antioxidant lithium battery copper foil, comprising the following steps: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in the copper plating solution, and perform electroplating to form a copper plating layer. Step 3: Immerse the polypropylene film with copper plating in an antioxidant solution for 5-10 seconds to form an antioxidant film and obtain antioxidant lithium battery copper foil.

[0008] Furthermore, in step 1, the thickness of the polypropylene film is 4 μm; The thickness of the transition copper layer is 60 nm; The thickness of the copper plating layer is 1 μm.

[0009] Furthermore, in step 1, the process conditions for magnetron sputtering are: sputtering power 40~60W, gas pressure 10~20Pa.

[0010] Furthermore, in step 2, the copper plating solution comprises the following components by mass: copper sulfate 10~20g / L, sodium hypophosphite 1~3g / L, and citric acid 45~65g / L; The solvent for the copper plating solution is deionized water; The pH value of the copper plating solution is 11-13.

[0011] Furthermore, in step 2, the electroplating process conditions are: temperature 35~45℃, current 1.0~1.6A, voltage 0.8~1.0V, and time 6~10min.

[0012] Furthermore, in step 3, the antioxidant liquid comprises the following components: by mass percentage, 2-mercaptobenzothiazole 2.2-2.5%, ethanol 7-9%, triethanolamine 0.6-0.8%, and sodium molybdate 0.3-0.5%; The antioxidant solution is made from deionized water.

[0013] Furthermore, in step 3, the antioxidant solution has a mass fraction of 3-5%.

[0014] Furthermore, the antioxidant liquid also contains modified carbon nanotubes, which are prepared by the following process: Thiol-modified carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide were mixed, ultrasonically treated, and irradiated with ultraviolet light. After the reaction was completed, the mixture was washed and dried to obtain modified carbon nanotubes.

[0015] Furthermore, the mass ratio of mercapto-modified carbon nanotubes, double-bonded fluorinated siloxanes, photoinitiators, and N,N-dimethylformamide is 1:(0.08~0.12):(0.01~0.03):(3~5).

[0016] Furthermore, the ultrasonic treatment process conditions are: frequency 40~60kHz, time 30~50min.

[0017] Furthermore, the process conditions for ultraviolet light irradiation are: ultraviolet wavelength 355~365nm, irradiation time 30~60min.

[0018] Furthermore, the drying process conditions are: temperature 70~80℃, time 30~50min.

[0019] Furthermore, the modified carbon nanotubes account for 2.5% to 4.5% of the mass of the antioxidant solution; Furthermore, the thiolized carbon nanotubes are prepared by the following process: Carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol were mixed, stirred until homogeneous, and heated under reflux. After the reaction was completed, the mixture was washed and dried to obtain mercaptolated carbon nanotubes.

[0020] Furthermore, the mass ratio of carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol is 1:(0.15~0.25):(5~10).

[0021] Furthermore, the process conditions for the heating and reflux reaction are: temperature 80~100℃, time 4~6h.

[0022] Furthermore, the drying process conditions are: temperature 70~80℃, time 30~50min.

[0023] Furthermore, the double-bonded fluorosiloxane is prepared by the following process: Propyltriethoxysilane isocyanate, 2-allyl-6-fluorophenol, toluene, and dibutyltin dilaurate are mixed and heated to react. The vacuum is adjusted to 5-10 kPa, and the reaction is continued for 1-2 hours to obtain a fluorinated siloxane with double bonds.

[0024] Furthermore, the molar ratio of propyltriethoxysilane isocyanate to 2-allyl-6-fluorophenol is (0.5~1.5):(1~3). The mass ratio of propyltriethoxysilane isocyanate, toluene, and dibutyltin dilaurate is 1:(5~10):(0.03~0.05).

[0025] Furthermore, the process conditions for the heating reaction are: temperature 70~80℃, time 4~6h.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. The antioxidant solution in this invention has a corrosion inhibitory effect on copper. The antioxidant solution does not contain zinc ions or chromium and other elements, which can meet the performance and safety requirements of high-end lithium battery manufacturers. The reagents used to prepare the antioxidant solution have low toxicity and good solderability, and subsequent wastewater treatment is relatively easy. The antioxidant liquid in this invention is colorless and does not require squeezing and cleaning with extrusion rollers. It can be directly washed with water, leaving no chemical residue on the foil surface. It can effectively improve the appearance abnormalities such as discoloration and whitening of composite copper foil. After high-temperature baking, the film surface is colorless. It can be stored for at least 6 months under normal temperature and humidity control conditions. It can effectively improve product quality and performance, thereby enhancing the stability of composite current collectors and improving the battery's lifespan and safety performance.

[0027] 2. The antioxidant liquid in this invention also contains modified carbon nanotubes. Carbon nanotubes have extremely high conductivity and form a continuous conductive path, which can improve the rate performance of the battery. However, carbon nanotubes have poor dispersion in the antioxidant liquid, resulting in an uneven antioxidant film. Therefore, they are modified. Modified carbon nanotubes are obtained by a mercapto-alkene click reaction of mercapto-methylated carbon nanotubes and double-bonded fluorinated siloxanes. The double-bonded fluorinated siloxanes can improve the dispersibility of carbon nanotubes in antioxidant solutions and reduce agglomeration. Mercapto-methylated carbon nanotubes are obtained by esterification of the carboxyl groups of carboxylated carbon nanotubes with the hydroxyl groups of 1,4-dimercapto-2,3-butanediol, thereby introducing mercapto groups. 1,4-dimercapto-2,3-butanediol contains two mercapto groups. One mercapto group is used for the click reaction with the double-bonded fluorinated siloxane, and the other mercapto group can form a complexation reaction with the copper ions in the copper plating layer, thereby enhancing the bonding force between the antioxidant film and the copper plating layer and comprehensively improving the performance of the antioxidant film. The double-bonded fluorinated siloxane is formed by the hydrolysis and condensation of the trimethoxysilane group of propyltriethoxysilane to form a siloxane skeleton. The isocyanate group reacts with the phenolic hydroxyl group of 2-allyl-6-fluorophenol under the action of a catalyst to introduce double bonds and fluorine. The fluorine migrates to the surface of the antioxidant film, achieving hydrophobic and electrolyte-resistant effects and extending the service life of the current collector. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the following specific implementation, The polypropylene film thickness is 4μm; The photoinitiator is 2,2-dimethoxy-2-acetophenone; Carboxylated carbon nanotubes, 4 nm in diameter; Copper target material, 99.99% purity.

[0030] Example 1: A method for preparing antioxidant lithium-ion battery copper foil, comprising the following processes: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a 60nm thick transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in a copper plating solution, and perform electroplating to form a 1μm thick copper plating layer; Step 3: Immerse the polypropylene film with the copper plating layer in a 5% (w / w) antioxidant solution for 10s to form an antioxidant film, obtaining an antioxidant lithium battery copper foil; In Step 1, the magnetron sputtering process conditions are: sputtering power 60W, gas pressure 20Pa; Step 2 In step 2, the copper plating solution comprises the following components by mass: 20 g / L copper sulfate, 3 g / L sodium hypophosphite, and 65 g / L citric acid; the solvent for the copper plating solution is deionized water; the pH value of the copper plating solution is 13; in step 3, the electroplating process conditions are: temperature 45℃, current 1.6A, voltage 1.0V, and time 10 min; in step 4, the antioxidant solution comprises the following components by mass percentage: 2.5% 2-mercaptobenzothiazole, 9% ethanol, 0.8% triethanolamine, and 0.5% sodium molybdate; the solvent for the antioxidant solution is deionized water.

[0031] Example 2: A method for preparing antioxidant lithium-ion battery copper foil, comprising the following processes: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a 60nm thick transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in a copper plating solution, and perform electroplating to form a 1μm thick copper plating layer; Step 3: Immerse the polypropylene film with the copper plating layer in a 4% (w / w) antioxidant solution for 8 seconds to form an antioxidant film, obtaining an antioxidant lithium battery copper foil; In Step 1, the magnetron sputtering process conditions are: sputtering power 50W, gas pressure 15Pa; Step 2 In step 2, the copper plating solution comprises the following components by mass: 15 g / L copper sulfate, 2 g / L sodium hypophosphite, and 55 g / L citric acid; the solvent for the copper plating solution is deionized water; the pH value of the copper plating solution is 12; in step 3, the electroplating process conditions are: temperature 40℃, current 1.3A, voltage 0.9V, and time 8 min; in step 4, the antioxidant solution comprises the following components by mass percentage: 2.3% 2-mercaptobenzothiazole, 8% ethanol, 0.7% triethanolamine, and 0.4% sodium molybdate; the solvent for the antioxidant solution is deionized water.

[0032] Example 3: A method for preparing antioxidant lithium-ion battery copper foil, comprising the following processes: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a 60nm thick transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in a copper plating solution, and perform electroplating to form a 1μm thick copper plating layer; Step 3: Immerse the polypropylene film with the copper plating layer in a 3% (w / w) antioxidant solution for 5s to form an antioxidant film, obtaining an antioxidant lithium battery copper foil; In Step 1, the magnetron sputtering process conditions are: sputtering power 40W, gas pressure 10Pa; Step 2 In step 2, the copper plating solution comprises the following components by mass: 10 g / L copper sulfate, 1 g / L sodium hypophosphite, and 45 g / L citric acid; the solvent for the copper plating solution is deionized water; the pH value of the copper plating solution is 11; in step 3, the electroplating process conditions are: temperature 35℃, current 1.0A, voltage 0.8V, and time 6 min; in step 4, the antioxidant solution comprises the following components by mass percentage: 2.2% 2-mercaptobenzothiazole, 7% ethanol, 0.6% triethanolamine, and 0.3% sodium molybdate; the solvent for the antioxidant solution is deionized water.

[0033] Example 4: A method for preparing antioxidant lithium-ion battery copper foil, comprising the following processes: (1) Preparation of modified carbon nanotubes: Carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol were mixed, stirred until homogeneous, and heated under reflux. After the reaction was completed, the mixture was washed and dried to obtain mercaptolated carbon nanotubes. The mass ratio of carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol was 1:0.25:10. The reflux reaction conditions were: temperature 100℃, time 6h; and the drying conditions were: temperature 80℃, time 50min. Propyltriethoxysilane isocyanate, 2-allyl-6-fluorophenol, toluene, and dibutyltin dilaurate were mixed and heated to react. The vacuum was adjusted to 10 kPa, and the reaction was continued for 2 hours to obtain a fluorosiloxane with double bonds. The molar ratio of propyltriethoxysilane to 2-allyl-6-fluorophenol was 1.5:3. The mass ratio of propyltriethoxysilane isocyanate, toluene, and dibutyltin dilaurate is 1:10:0.05; the process conditions for the heating reaction are: temperature 80℃, time 6h; Thiolized carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide were mixed, ultrasonically treated, and irradiated with ultraviolet light. After the reaction, the mixture was washed and dried to obtain modified carbon nanotubes. The mass ratio of thiolized carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide was 1:0.12:0.03:5. The ultrasonic treatment conditions were: frequency 60 kHz, time 50 min; the ultraviolet irradiation conditions were: ultraviolet wavelength 365 nm, irradiation time 60 min; and the drying conditions were: temperature 80℃, time 50 min. (2) Preparation of antioxidant lithium battery copper foil: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a 60nm thick transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in a copper plating solution, and perform electroplating to form a 1μm thick copper plating layer; Step 3: Immerse the polypropylene film with the copper plating layer in a 5% (w / w) antioxidant solution for 10s to form an antioxidant film, obtaining an antioxidant lithium battery copper foil; In Step 1, the magnetron sputtering process conditions are: sputtering power 60W, gas pressure 20Pa; In Step 2, the copper plating solution includes... The following components are included by mass: copper sulfate 20 g / L, sodium hypophosphite 3 g / L, citric acid 65 g / L; the solvent for the copper plating solution is deionized water; the pH value of the copper plating solution is 13; in step 2, the electroplating process conditions are: temperature 45℃, current 1.6A, voltage 1.0V, time 10 min; in step 3, the antioxidant solution includes the following components by mass percentage: 2-mercaptobenzothiazole 2.5%, ethanol 9%, triethanolamine 0.8%, sodium molybdate 0.5%, modified carbon nanotubes 4.5%; the solvent for the antioxidant solution is deionized water.

[0034] Example 5: A method for preparing antioxidant lithium-ion battery copper foil, comprising the following processes: (1) Preparation of modified carbon nanotubes: Carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol were mixed, stirred until homogeneous, and heated under reflux. After the reaction was completed, the mixture was washed and dried to obtain mercaptolated carbon nanotubes. The mass ratio of carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol was 1:0.20:8. The reflux reaction conditions were: temperature 90℃, time 5h; and the drying conditions were: temperature 75℃, time 40min. Propyltriethoxysilane isocyanate, 2-allyl-6-fluorophenol, toluene, and dibutyltin dilaurate were mixed and heated to react. The vacuum was adjusted to 8 kPa, and the reaction was continued for 1.5 h to obtain a fluorosiloxane with double bonds. The molar ratio of propyltriethoxysilane isocyanate to 2-allyl-6-fluorophenol was 1.0:2. The mass ratio of propyltriethoxysilane isocyanate, toluene, and dibutyltin dilaurate is 1:8:0.04; the process conditions for the heating reaction are: temperature 75℃, time 5h; Thiolized carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide were mixed, ultrasonically treated, and irradiated with ultraviolet light. After the reaction, the mixture was washed and dried to obtain modified carbon nanotubes. The mass ratio of thiolized carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide was 1:0.10:0.02:4. The ultrasonic treatment conditions were: frequency 50 kHz, time 40 min; the ultraviolet irradiation conditions were: ultraviolet wavelength 360 nm, irradiation time 45 min; and the drying conditions were: temperature 75℃, time 40 min. (2) Preparation of antioxidant lithium battery copper foil: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a 60nm thick transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in a copper plating solution, and perform electroplating to form a 1μm thick copper plating layer; Step 3: Immerse the polypropylene film with the copper plating layer in a 4% (w / w) antioxidant solution for 8 seconds to form an antioxidant film, obtaining an antioxidant lithium battery copper foil; In Step 1, the magnetron sputtering process conditions are: sputtering power 50W, gas pressure 15Pa; In Step 2, the copper plating solution includes... The following components are included by mass: copper sulfate 15 g / L, sodium hypophosphite 2 g / L, citric acid 55 g / L; the solvent of the copper plating solution is deionized water; the pH value of the copper plating solution is 12; in step 2, the electroplating process conditions are: temperature 40℃, current 1.3A, voltage 0.9V, time 8min; in step 3, the antioxidant solution includes the following components by mass percentage: 2-mercaptobenzothiazole 2.3%, ethanol 8%, triethanolamine 0.7%, sodium molybdate 0.4%, modified carbon nanotubes 3.5%; the solvent of the antioxidant solution is deionized water.

[0035] Example 6: A method for preparing antioxidant lithium-ion battery copper foil, comprising the following processes: (1) Preparation of modified carbon nanotubes: Carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol were mixed, stirred until homogeneous, and heated under reflux. After the reaction was completed, the mixture was washed and dried to obtain mercaptolated carbon nanotubes. The mass ratio of carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol was 1:0.15:5. The reflux reaction conditions were: temperature 80℃, time 4h; the drying conditions were: temperature 70℃, time 30min. Propyltriethoxysilane isocyanate, 2-allyl-6-fluorophenol, toluene, and dibutyltin dilaurate were mixed and heated to react. The vacuum was adjusted to 5 kPa, and the reaction was continued for 1 h to obtain a fluorosiloxane with double bonds. The molar ratio of propyltriethoxysilane to 2-allyl-6-fluorophenol was 0.5:1. The mass ratio of propyltriethoxysilane isocyanate, toluene, and dibutyltin dilaurate is 1:5:0.03; the process conditions for the heating reaction are: temperature 70℃, time 4h; Thiolized carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide were mixed, ultrasonically treated, and irradiated with ultraviolet light. After the reaction, the mixture was washed and dried to obtain modified carbon nanotubes. The mass ratio of thiolized carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide was 1:0.08:0.01:3. The ultrasonic treatment conditions were: frequency 40 kHz, time 30 min; the ultraviolet irradiation conditions were: ultraviolet wavelength 355 nm, irradiation time 30 min; and the drying conditions were: temperature 70℃, time 30 min. (2) Preparation of antioxidant lithium battery copper foil: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a 60nm thick transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in a copper plating solution, and perform electroplating to form a 1μm thick copper plating layer; Step 3: Immerse the polypropylene film with the copper plating layer in a 3% (w / w) antioxidant solution for 5 seconds to form an antioxidant film, obtaining an antioxidant lithium battery copper foil; In Step 1, the magnetron sputtering process conditions are: sputtering power 40W, gas pressure 10Pa; In Step 2, the copper plating solution includes... The following components are included by mass: copper sulfate 10 g / L, sodium hypophosphite 1 g / L, citric acid 45 g / L; the solvent of the copper plating solution is deionized water; the pH value of the copper plating solution is 11; in step 2, the electroplating process conditions are: temperature 35℃, current 1.0A, voltage 0.8V, time 6min; in step 3, the antioxidant solution includes the following components by mass percentage: 2-mercaptobenzothiazole 2.2%, ethanol 7%, triethanolamine 0.6%, sodium molybdate 0.3%, modified carbon nanotubes 2.5%; the solvent of the antioxidant solution is deionized water.

[0036] Comparative Example 1: Compared with Example 1, 2-mercaptobenzothiazole was replaced with benzotriazole, while the other conditions remained unchanged.

[0037] Comparative Example 2: Compared with Example 1, triethanolamine was replaced with sodium hydroxide, while other conditions remained unchanged.

[0038] Comparative Example 3: Compared with Example 1, sodium molybdate was replaced with potassium molybdate, while other conditions remained unchanged.

[0039] Comparative Example 4: Compared with Example 1, the mass fraction of the antioxidant solution was adjusted to 1%, while the other conditions remained unchanged.

[0040] Comparative Example 5: Compared with Example 4, the double-bonded fluorinated siloxane was replaced with 3-aminopropyltriethoxysilane, while the other conditions remained unchanged.

[0041] Comparative Example 6: Compared with Example 4, no modification was made to the carbon nanotubes, and all other conditions remained unchanged.

[0042] Experiment: The antioxidant lithium battery copper foils obtained in the examples and comparative examples were tested for various properties; Appearance defect rate: Take the anti-oxidation lithium battery copper foil, bake it at 145℃ for 15 minutes, and inspect it visually. The standard is that there are no oxidation marks such as mottled appearance or color difference. Room temperature storage time: Take the anti-oxidation lithium battery copper foil and place it in an environment with a temperature of 25℃ and a humidity of 50%, without PE film wrapping protection, and test its longest storage time in the non-oxidized state; Resistivity: The resistivity of the anti-oxidation lithium battery copper foil was measured using a DC resistance meter.

[0043]

[0044] Based on the data in the table above, the following conclusions can be drawn: Compared with Example 1, the appearance defect rate of Comparative Examples 1-3 increased significantly, the room temperature storage time decreased, and the resistivity increased. This is because mercaptobenzothiazole and sodium molybdate can bridge copper ions through chemical bonds and can be adsorbed on the surface of the copper layer. With the participation of triethanolamine, a dense and uniform organic protective film is formed on the copper surface, which can reduce the permeability of oxygen or water, effectively prevent copper surface oxidation, improve product quality and performance, and thus improve the stability of the composite current collector, improve the battery life and safety performance. Compared with Example 1, Comparative Example 4 adjusted the mass fraction of the antioxidant solution to 1%, and the room temperature standing time decreased while the resistivity increased, indicating that the mass fraction of the antioxidant solution in this application is optimal when controlled at 3~5%. Compared with Example 4, Comparative Example 5 replaced the double-bonded fluorinated siloxane with 3-aminopropyltriethoxysilane. The room temperature standing time decreased and the resistivity increased. This is because the double bonds in the double-bonded fluorinated siloxane react with the mercaptoized carbon nanotubes under the action of the initiator, thereby enhancing the dispersibility of the carbon nanotubes, making the antioxidant film denser, and fluorine will migrate to the surface of the antioxidant film, achieving the effects of hydrophobicity and electrolyte resistance, and extending the service life of the current collector. Compared with Example 4, Comparative Example 6 did not modify the carbon nanotubes, and the resistivity increased because the carbon nanotubes were poorly dispersed in the antioxidant solution. Without modification, the density of the antioxidant film would decrease. In summary, the formulation of the antioxidant solution in this application can enhance the overall performance of the prepared antioxidant lithium battery copper foil.

[0045] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing antioxidant lithium-ion battery copper foil, characterized in that: Includes the following steps: Step 1: Take a polypropylene film and use a copper target to perform magnetron sputtering on its upper and lower surfaces to form a transition copper layer; Step 2: Take the polypropylene film with the sputtered transition copper layer, place it in the copper plating solution, and perform electroplating to form a copper plating layer. Step 3: Immerse the polypropylene film with copper plating in an antioxidant solution for 5-10 seconds to form an antioxidant film and obtain antioxidant lithium battery copper foil; In step 3, the antioxidant liquid comprises the following components: by mass percentage, 2-mercaptobenzothiazole 2.2~2.5%, ethanol 7~9%, triethanolamine 0.6~0.8%, and sodium molybdate 0.3~0.5%.

2. The method for preparing an antioxidant lithium battery copper foil according to claim 1, characterized in that: In step 3, the antioxidant solution has a mass fraction of 3-5%.

3. The method for preparing an antioxidant lithium battery copper foil according to claim 2, characterized in that: In step 1, the polypropylene film has a thickness of 4 μm; The thickness of the transition copper layer is 60 nm; The thickness of the copper plating layer is 1 μm.

4. The method for preparing an antioxidant lithium-ion battery copper foil according to claim 3, characterized in that: In step 1, the process conditions for magnetron sputtering are: sputtering power 40~60W, gas pressure 10~20Pa.

5. The method for preparing an antioxidant lithium battery copper foil according to claim 4, characterized in that: In step 2, the copper plating solution includes the following components by mass: copper sulfate 10~20g / L, sodium hypophosphite 1~3g / L, and citric acid 45~65g / L; The solvent for the copper plating solution is deionized water; The pH value of the copper plating solution is 11-13.

6. The method for preparing an antioxidant lithium battery copper foil according to claim 5, characterized in that: In step 2, the electroplating process conditions are: temperature 35~45℃, current 1.0~1.6A, voltage 0.8~1.0V, and time 6~10min.

7. The method for preparing an antioxidant lithium battery copper foil according to claim 1, characterized in that: The antioxidant liquid also contains modified carbon nanotubes, which are prepared by the following process: Thiol-modified carbon nanotubes, double-bonded fluorosiloxanes, photoinitiators, and N,N-dimethylformamide were mixed, ultrasonically treated, and irradiated with ultraviolet light. After the reaction was completed, the mixture was washed and dried to obtain modified carbon nanotubes.

8. The method for preparing an antioxidant lithium battery copper foil according to claim 7, characterized in that: The thiolized carbon nanotubes are prepared by the following process: Carboxylated carbon nanotubes, deionized water, and 1,4-dimercapto-2,3-butanediol were mixed, stirred until homogeneous, and heated under reflux. After the reaction was completed, the mixture was washed and dried to obtain mercaptolated carbon nanotubes.

9. The method for preparing an antioxidant lithium battery copper foil according to claim 7, characterized in that: The double-bonded fluorinated siloxane is prepared by the following process: Propyltriethoxysilane isocyanate, 2-allyl-6-fluorophenol, toluene, and dibutyltin dilaurate are mixed and heated to react. The vacuum is adjusted to 5-10 kPa, and the reaction is continued for 1-2 hours to obtain a fluorinated siloxane with double bonds.

10. An antioxidant copper foil for lithium batteries, characterized in that: The preparation method according to any one of claims 1 to 9 is used.

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