A thin film aluminum-plated composite current collector and a preparation method thereof

Abstract

The application discloses a thin film aluminum-plated composite current collector and a preparation method thereof, and relates to the technical field of current collectors. The application firstly performs low-temperature plasma treatment on a base film to introduce hydroxyl groups, then immerses the base film into a modified liquid containing an acylhydrazone bond intermediate A, and forms a modified base film containing a dynamic covalent bond through heating and epoxy ring opening crosslinking; subsequently, a micron-level aluminum layer is deposited on both sides of the base film through magnetron sputtering and vacuum evaporation; finally, the aluminum layer is subjected to gradient heat treatment assisted by a magnetic field to optimize the grain orientation and refine the grains of the aluminum layer; the dynamic covalent bond layer forms a coordination bond with aluminum atoms through a nitrogen-containing functional group to improve the interface bonding strength, and the dynamic covalent bond and the crosslinking network endow the base film with excellent stability and electrolyte blocking ability; the gradient heat treatment assisted by the magnetic field optimizes the electrical conductivity and mechanical properties of the aluminum layer in cooperation, and also releases the internal stress of the film, effectively avoiding product curling or cracking. The thin film aluminum-plated composite current collector prepared by the application has the effects of good electrical conductivity, high interface bonding and excellent electrochemical stability.

Description

Technical Field

[0001] This invention relates to the field of current collector technology, specifically to a thin-film aluminum-coated composite current collector and its preparation method. Background Technology

[0002] This invention relates to the field of current collector technology, specifically to thin-film aluminized composite current collectors. Composite current collectors, due to their advantages of being lightweight, highly conductive, and having good flexibility, have broad application prospects in energy storage fields such as lithium-ion batteries. Among them, thin-film aluminized composite current collectors have become a research hotspot due to their controllable manufacturing costs and excellent conductivity.

[0003] However, existing thin-film aluminized composite current collector fabrication technologies generally suffer from insufficient interfacial bonding strength between the polymer base film and the aluminum layer, leading to easy detachment and peeling of the aluminum layer. Simultaneously, the base film exhibits poor stability, allowing electrolyte to easily penetrate and corrode it, thus affecting the current collector's lifespan. Furthermore, the disordered grain orientation and uneven size of the aluminized layer limit its conductivity and mechanical properties, and the fabrication process easily generates internal stress, causing product curling and cracking, severely restricting its large-scale application in high-performance energy storage devices. Therefore, developing a thin-film aluminized composite current collector fabrication technology with strong interfacial bonding, excellent electrochemical stability, and superior conductivity has become a pressing technical challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a thin-film aluminum-coated composite current collector and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a thin-film aluminum-coated composite current collector, comprising the following steps: (1) Terephthalaldehyde, oxaloyl dihydrazine and organic solvent are mixed in a mass ratio of 1~2:1:20. Under a nitrogen atmosphere, the mixture is heated to 60~80℃ and stirred at 500rpm for 1~3h. After naturally cooling to room temperature, a solution containing intermediate A is obtained. Then, a crosslinking agent of 2~3 times the mass of terephthalaldehyde and a catalyst of 0.01 times the total mass of the reaction solution are added. The mixture is stirred at 500rpm for 30min to obtain the self-made modified solution. (2) The pretreated polymer base film is subjected to low-temperature plasma treatment for 1~3 min to obtain a surface-activated base film, which is then immersed in a self-made modification solution for 30 min, slowly pulled out, and placed in a vacuum oven at 100℃ for 1 h to obtain a modified base film. (3) After the modified base film is deposited with aluminum layer by magnetron sputtering on both sides, it is then vacuum evaporated until the total thickness of the aluminum layer on both sides is 1~2μm. After evaporation is stopped, the film is cooled to room temperature to obtain a double-sided aluminum base film. The film is then placed in a vertical magnetic field and subjected to gradient heating heat treatment under nitrogen atmosphere. After natural cooling to room temperature, a thin film aluminum composite current collector is obtained.

[0006] Furthermore, the organic solvent in step (1) is DMF.

[0007] Furthermore, the crosslinking agent in step (1) is 4,4'-diaminodiphenylmethane diglycidyl ether.

[0008] Furthermore, the catalyst in step (1) is triethylamine.

[0009] Furthermore, the polymer base film in step (2) is a PET film with a thickness of 5 μm.

[0010] Furthermore, the plasma in step (2) is oxygen.

[0011] Furthermore, the slow lifting speed described in step (2) is 2 mm / s.

[0012] Furthermore, the thickness of the deposited aluminum layer in step (3) is 100 nm.

[0013] Furthermore, the vertical magnetic field strength in step (3) is 0.5T.

[0014] Further, the gradient heating process in step (3) is as follows: heating to 120°C at a heating rate of 5°C / min and holding for 30 min; then heating to 150°C at a heating rate of 3°C / min and holding for 1 h; finally heating to 180°C at a heating rate of 2°C / min and holding for 30 min.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention uses a self-made modified base film to deposit an aluminum-coated layer, followed by magnetic field-assisted gradient heat treatment, to achieve good conductivity, high interfacial bonding, and excellent electrochemical stability.

[0016] This invention first introduces active groups into a pretreated polymer base film material through low-temperature plasma treatment, then immerses it in a self-made modification solution prepared by mixing intermediate A (containing acylhydrazone bonds) formed by the condensation of terephthalaldehyde and oxalohydrazide, 4,4'-diaminodiphenylmethane diglycidyl ether, and a catalyst. After heating and epoxy ring-opening crosslinking, a modified base film containing dynamic covalent bonds is obtained. Then, aluminum layers are deposited on both sides of the modified base film using magnetron sputtering technology. After vacuum evaporation to thicken to the micrometer level, the aluminum layer is subjected to gradient heat treatment under magnetic field assistance to obtain a thin-film aluminum-coated composite current collector. The polymer base film material is surface-activated by introducing hydroxyl groups through low-temperature plasma treatment. The aluminum atoms form a dynamic covalent bond layer through ring-opening crosslinking with the epoxy groups in the self-made modified liquid. During the subsequent aluminum plating process, the aluminum atoms are in a highly active state and can form coordination bonds with the lone pairs of electrons of the nitrogen-containing functional groups in the dynamic covalent bond layer, thereby significantly improving the interfacial bonding strength. At the same time, the reversibility of the dynamic covalent bond and the crosslinking network synergistically endow the base film with good thermal stability and act as a barrier to prevent the electrolyte from penetrating the base film. Finally, with the assistance of a magnetic field, the orientation of the aluminum layer grains is controlled to optimize its electrical and mechanical properties. The gradient heat treatment process refines the aluminum layer grains, further enhances the interfacial chemical bonding, and can also release the internal stress of the film to avoid curling or cracking. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The testing methods for various indicators of the sunscreen and antioxidant cosmetics prepared in the following embodiments are as follows: Interfacial adhesion test: A vertical tensile testing machine was used to perform a coating pull-out test on the composite current collector to evaluate the interfacial adhesion of the resistive composite current collector. The test method is as follows: 3M double-sided tape (150mm long, 20mm wide) and composite current collector samples (160mm long, 30mm wide) prepared in Examples 1-5 and Comparative Examples 1-6 were sequentially pasted onto a stainless steel plate. A 1kg pressure roller was used to roll the 3M 681 single-sided tape on the surface of the stainless steel plate three times at a uniform speed in the same direction to ensure that the composite current collector sample was fully adhered to the 3M double-sided tape on the stainless steel plate. Then, 3M 681 single-sided tape (60mm long, 20mm wide) was adhered to the surface of the finished product. The end of the 3M 681 single-sided tape was connected to a strip of white paper (150mm long, 20mm wide) 5mm from the end to be fixed to the fixture. The stainless steel plate was horizontally fixed on the tensile testing machine fixture, and a 180° coating pull-out test was performed at a speed of 500mm / min. Electrochemical stability test: The electrochemical stability test of the composite current collector was carried out by immersion experiment using TC-E8633S high-temperature electrolyte. 2cm×2cm composite current collector samples prepared in Examples 1-5 and Comparative Examples 1-6 were cut off (ensuring no burrs on the cut edges) and placed in a cut and semi-sealed aluminum-plastic film. 10mL of the above electrolyte and an appropriate amount of water (water content 200ppm, i.e., 200μg of water in 1ml of electrolyte) were added and then sealed. The film was placed in an oven at 60°C. The coating peeling was checked after 1 day, 3 days and 7 days. Conductivity test: The sheet resistance was used for characterization. The flat composite current collector samples prepared in Examples 1-5 and Comparative Examples 1-6 were placed on the sample stage, and the sheet resistance of the samples was tested using a four-probe sheet resistance meter. Example 1

[0019] (1) Cut a PET base film with a thickness of 5 μm into a square sample of 10 cm × 10 cm, put it into an ultrasonic cleaner, and ultrasonically clean it with anhydrous ethanol and deionized water for 15 min in sequence. The ultrasonic power is 150 W. After cleaning, place the base film in an oven at 60 °C and a vacuum of -0.09 MPa for 2 h to dry. Then, perform low-temperature plasma treatment for 1 min to obtain a surface-activated base film. The plasma is oxygen, the gas flow rate is 20 sccm, the reaction chamber pressure is 10 Pa, and the treatment power is 100 W to introduce hydroxyl groups on the surface of the base film. (2) Terephthalaldehyde, oxaloyl dihydrazide and DMF were mixed in a mass ratio of 1:1:20. Under a nitrogen atmosphere, the mixture was heated to 60°C and stirred at 500 rpm for 1 h. After naturally cooling to room temperature, a solution containing intermediate A was obtained. Then, 4,4'-diaminodiphenylmethane diglycidyl ether with a mass of 2 times that of terephthalaldehyde and triethylamine with a mass of 0.01 times that of the total reaction solution were added. The mixture was stirred at 500 rpm for 30 min to obtain the self-made modified solution. (3) Immerse the surface-activated base film completely in the self-made modification liquid, ensuring that no air bubbles adhere to the base film. Soak for 30 minutes, then slowly lift it out at a speed of 2 mm / s to make the liquid film uniform. Place it in an oven at 100℃ and a vacuum of -0.09 MPa for 1 hour to obtain the modified base film. (4) Place the modified base film into a magnetron sputtering coating machine and evacuate the cavity until the vacuum level reaches 5×10⁻⁶. -4 Pa, sputtering parameters were set as follows: target material was 99.99% high-purity aluminum target, sputtering gas was argon, gas flow rate was 30 sccm, sputtering power was 150 W, substrate temperature was room temperature. Pre-sputtering was performed for 5 minutes to remove the oxide layer on the aluminum target surface. Then, a 100 nm thick aluminum layer was sputtered onto one side of the substrate film. After single-sided deposition, the substrate film was flipped, and the same parameters were used to sputter and deposit an aluminum layer on the other side. After sputtering, the deposition chamber was kept under vacuum for 5 minutes, then slowly vented to atmospheric pressure. The sample was removed and placed in the sample chamber of the vacuum evaporator, and the vacuum was evacuated to 2 × 10⁻⁶. -5 Pa, set the evaporation parameters: the evaporation source is 99.99% high-purity aluminum wire, the evaporation temperature is 1200℃, the evaporation rate is 0.5nm / s, and continue evaporation until the total thickness of the double-sided aluminum coating is 1μm. Then stop evaporation, maintain the cavity in a vacuum state for 10min, and then cool to room temperature at a rate of 5℃ / min. Slowly release the gas to normal pressure to obtain a double-sided aluminum base film. (5) Place the double-sided aluminum-coated base film in a magnetic field-assisted heat treatment furnace. Under a nitrogen atmosphere, set the magnetic field strength to 0.5T and the magnetic field direction to be perpendicular to the plane of the base film. Heat the film to 120℃ at a heating rate of 5℃ / min and hold for 30min. Then heat the film to 150℃ at a heating rate of 3℃ / min and hold for 1h. Finally, heat the film to 180℃ at a heating rate of 2℃ / min and hold for 30min. After naturally cooling to room temperature, the thin film aluminum-coated composite current collector is obtained. Example 2

[0020] (1) Cut a PET base film with a thickness of 5 μm into a square sample of 10 cm × 10 cm, put it into an ultrasonic cleaner, and ultrasonically clean it with anhydrous ethanol and deionized water for 15 min in sequence. The ultrasonic power is 150 W. After cleaning, place the base film in an oven at 60 °C and a vacuum of -0.09 MPa for 2 h to dry. Then, perform low-temperature plasma treatment for 1.5 min to obtain a surface-activated base film. The plasma is oxygen, the gas flow rate is 20 sccm, the reaction chamber pressure is 10 Pa, and the treatment power is 100 W to introduce hydroxyl groups on the surface of the base film. (2) Terephthalaldehyde, oxaloyl dihydrazide and DMF were mixed in a mass ratio of 1.2:1:20. Under a nitrogen atmosphere, the mixture was heated to 65°C and stirred at 500 rpm for 1.5 h. After naturally cooling to room temperature, a solution containing intermediate A was obtained. Then, 4,4'-diaminodiphenylmethane diglycidyl ether (2.2 times the mass of terephthalaldehyde) and triethylamine (0.01 times the total mass of the reaction solution) were added. The mixture was stirred at 500 rpm for 30 min to obtain the self-made modified solution. (3) Immerse the surface-activated base film completely in the self-made modification liquid, ensuring that no air bubbles adhere to the base film. Soak for 30 minutes, then slowly lift it out at a speed of 2 mm / s to make the liquid film uniform. Place it in an oven at 100℃ and a vacuum of -0.09 MPa for 1 hour to obtain the modified base film. (4) Place the modified base film into a magnetron sputtering coating machine and evacuate the cavity until the vacuum level reaches 5×10⁻⁶. -4 Pa, sputtering parameters were set as follows: target material was 99.99% high-purity aluminum target, sputtering gas was argon, gas flow rate was 30 sccm, sputtering power was 150 W, substrate temperature was room temperature. Pre-sputtering was performed for 5 minutes to remove the oxide layer on the aluminum target surface. Then, a 100 nm thick aluminum layer was sputtered onto one side of the substrate film. After single-sided deposition, the substrate film was flipped, and the same parameters were used to sputter and deposit an aluminum layer on the other side. After sputtering, the deposition chamber was kept under vacuum for 5 minutes, then slowly vented to atmospheric pressure. The sample was removed and placed in the sample chamber of the vacuum evaporator, and the vacuum was evacuated to 2 × 10⁻⁶. -5 Pa, set the evaporation parameters: the evaporation source is 99.99% high-purity aluminum wire, the evaporation temperature is 1200℃, the evaporation rate is 0.5nm / s, and continue evaporation until the total thickness of the double-sided aluminum coating is 1.2μm on each side. Then stop evaporation, maintain the cavity in a vacuum state for 10min, and then cool to room temperature at a rate of 5℃ / min. Slowly release the gas to normal pressure to obtain a double-sided aluminum base film. (5) Place the double-sided aluminum-coated base film in a magnetic field-assisted heat treatment furnace. Under a nitrogen atmosphere, set the magnetic field strength to 0.5T and the magnetic field direction to be perpendicular to the plane of the base film. Heat the film to 120℃ at a heating rate of 5℃ / min and hold for 30min. Then heat the film to 150℃ at a heating rate of 3℃ / min and hold for 1h. Finally, heat the film to 180℃ at a heating rate of 2℃ / min and hold for 30min. After naturally cooling to room temperature, the thin film aluminum-coated composite current collector is obtained. Example 3

[0021] (1) Cut a PET base film with a thickness of 5 μm into a square sample of 10 cm × 10 cm, put it into an ultrasonic cleaner, and ultrasonically clean it with anhydrous ethanol and deionized water for 15 min in sequence. The ultrasonic power is 150 W. After cleaning, place the base film in an oven at 60 °C and a vacuum of -0.09 MPa for 2 h to dry. Then, perform low-temperature plasma treatment for 2 min to obtain a surface-activated base film. The plasma is oxygen, the gas flow rate is 20 sccm, the reaction chamber pressure is 10 Pa, and the treatment power is 100 W to introduce hydroxyl groups on the surface of the base film. (2) Terephthalaldehyde, oxaloyl dihydrazide and DMF were mixed in a mass ratio of 1.5:1:20. Under a nitrogen atmosphere, the mixture was heated to 70°C and stirred at 500 rpm for 2 h. After naturally cooling to room temperature, a solution containing intermediate A was obtained. Then, 4,4'-diaminodiphenylmethane diglycidyl ether (2.5 times the mass of terephthalaldehyde) and triethylamine (0.01 times the total mass of the reaction solution) were added. The mixture was stirred at 500 rpm for 30 min to obtain the self-made modified solution. (3) Immerse the surface-activated base film completely in the self-made modification liquid, ensuring that no air bubbles adhere to the base film. Soak for 30 minutes, then slowly lift it out at a speed of 2 mm / s to make the liquid film uniform. Place it in an oven at 100℃ and a vacuum of -0.09 MPa for 1 hour to obtain the modified base film. (4) Place the modified base film into a magnetron sputtering coating machine and evacuate the cavity until the vacuum level reaches 5×10⁻⁶. -4 Pa, sputtering parameters were set as follows: target material was 99.99% high-purity aluminum target, sputtering gas was argon, gas flow rate was 30 sccm, sputtering power was 150 W, substrate temperature was room temperature. Pre-sputtering was performed for 5 minutes to remove the oxide layer on the aluminum target surface. Then, a 100 nm thick aluminum layer was sputtered onto one side of the substrate film. After single-sided deposition, the substrate film was flipped, and the same parameters were used to sputter and deposit an aluminum layer on the other side. After sputtering, the deposition chamber was kept under vacuum for 5 minutes, then slowly vented to atmospheric pressure. The sample was removed and placed in the sample chamber of the vacuum evaporator, and the vacuum was evacuated to 2 × 10⁻⁶. -5 Pa, set the evaporation parameters: the evaporation source is 99.99% high-purity aluminum wire, the evaporation temperature is 1200℃, the evaporation rate is 0.5nm / s, and continue evaporation until the total thickness of the double-sided aluminum coating is 1.5μm. Then stop evaporation, maintain the cavity in a vacuum state for 10min, and then cool to room temperature at a rate of 5℃ / min. Slowly release the gas to normal pressure to obtain a double-sided aluminum base film. (5) Place the double-sided aluminum-coated base film in a magnetic field-assisted heat treatment furnace. Under a nitrogen atmosphere, set the magnetic field strength to 0.5T and the magnetic field direction to be perpendicular to the plane of the base film. Heat the film to 120℃ at a heating rate of 5℃ / min and hold for 30min. Then heat the film to 150℃ at a heating rate of 3℃ / min and hold for 1h. Finally, heat the film to 180℃ at a heating rate of 2℃ / min and hold for 30min. After naturally cooling to room temperature, the thin film aluminum-coated composite current collector is obtained. Example 4

[0022] (1) Cut a PET base film with a thickness of 5 μm into a square sample of 10 cm × 10 cm, put it into an ultrasonic cleaner, and ultrasonically clean it with anhydrous ethanol and deionized water for 15 min in sequence. The ultrasonic power is 150 W. After cleaning, place the base film in an oven at 60 °C and a vacuum of -0.09 MPa for 2 h to dry. Then, perform low-temperature plasma treatment for 2.5 min to obtain a surface-activated base film. The plasma is oxygen, the gas flow rate is 20 sccm, the reaction chamber pressure is 10 Pa, and the treatment power is 100 W to introduce hydroxyl groups on the surface of the base film. (2) Terephthalaldehyde, oxaloyl dihydrazide and DMF were mixed in a mass ratio of 1.8:1:20. Under a nitrogen atmosphere, the mixture was heated to 75°C and stirred at 500 rpm for 2.5 h. After naturally cooling to room temperature, a solution containing intermediate A was obtained. Then, 4,4'-diaminodiphenylmethane diglycidyl ether (2.8 times the mass of terephthalaldehyde) and triethylamine (0.01 times the total mass of the reaction solution) were added. The mixture was stirred at 500 rpm for 30 min to obtain the self-made modified solution. (3) Immerse the surface-activated base film completely in the self-made modification liquid, ensuring that no air bubbles adhere to the base film. Soak for 30 minutes, then slowly lift it out at a speed of 2 mm / s to make the liquid film uniform. Place it in an oven at 100℃ and a vacuum of -0.09 MPa for 1 hour to obtain the modified base film. (4) Place the modified base film into a magnetron sputtering coating machine and evacuate the cavity until the vacuum level reaches 5×10⁻⁶. -4 Pa, sputtering parameters were set as follows: target material was 99.99% high-purity aluminum target, sputtering gas was argon, gas flow rate was 30 sccm, sputtering power was 150 W, substrate temperature was room temperature. Pre-sputtering was performed for 5 minutes to remove the oxide layer on the aluminum target surface. Then, a 100 nm thick aluminum layer was sputtered onto one side of the substrate film. After single-sided deposition, the substrate film was flipped, and the same parameters were used to sputter and deposit an aluminum layer on the other side. After sputtering, the deposition chamber was kept under vacuum for 5 minutes, then slowly vented to atmospheric pressure. The sample was removed and placed in the sample chamber of the vacuum evaporator, and the vacuum was evacuated to 2 × 10⁻⁶. -5Pa, set the evaporation parameters: the evaporation source is 99.99% high-purity aluminum wire, the evaporation temperature is 1200℃, the evaporation rate is 0.5nm / s, and continue evaporation until the total thickness of the double-sided aluminum coating is 1.8μm. Then stop evaporation, maintain the cavity in a vacuum state for 10min, and then cool to room temperature at a rate of 5℃ / min. Slowly release the gas to normal pressure to obtain a double-sided aluminum base film. (5) Place the double-sided aluminum-coated base film in a magnetic field-assisted heat treatment furnace. Under a nitrogen atmosphere, set the magnetic field strength to 0.5T and the magnetic field direction to be perpendicular to the plane of the base film. Heat the film to 120℃ at a heating rate of 5℃ / min and hold for 30min. Then heat the film to 150℃ at a heating rate of 3℃ / min and hold for 1h. Finally, heat the film to 180℃ at a heating rate of 2℃ / min and hold for 30min. After naturally cooling to room temperature, the thin film aluminum-coated composite current collector is obtained. Example 5

[0023] (1) Cut a PET base film with a thickness of 5 μm into a square sample of 10 cm × 10 cm, put it into an ultrasonic cleaner, and ultrasonically clean it with anhydrous ethanol and deionized water for 15 min in sequence. The ultrasonic power is 150 W. After cleaning, place the base film in an oven at 60 °C and a vacuum of -0.09 MPa for 2 h to dry. Then, perform low-temperature plasma treatment for 3 min to obtain a surface-activated base film. The plasma is oxygen, the gas flow rate is 20 sccm, the reaction chamber pressure is 10 Pa, and the treatment power is 100 W to introduce hydroxyl groups on the surface of the base film. (2) Terephthalaldehyde, oxaloyl dihydrazide and DMF were mixed in a mass ratio of 2:1:20. Under a nitrogen atmosphere, the mixture was heated to 80°C and stirred at 500 rpm for 3 hours. After naturally cooling to room temperature, a solution containing intermediate A was obtained. Then, 4,4'-diaminodiphenylmethane diglycidyl ether (3 times the mass of terephthalaldehyde) and triethylamine (0.01 times the total mass of the reaction solution) were added. The mixture was stirred at 500 rpm for 30 minutes to obtain the self-made modified solution. (3) Immerse the surface-activated base film completely in the self-made modification liquid, ensuring that no air bubbles adhere to the base film. Soak for 30 minutes, then slowly lift it out at a speed of 2 mm / s to make the liquid film uniform. Place it in an oven at 100℃ and a vacuum of -0.09 MPa for 1 hour to obtain the modified base film. (4) Place the modified base film into a magnetron sputtering coating machine and evacuate the cavity until the vacuum level reaches 5×10⁻⁶. -4Pa, sputtering parameters were set as follows: target material was 99.99% high-purity aluminum target, sputtering gas was argon, gas flow rate was 30 sccm, sputtering power was 150 W, substrate temperature was room temperature. Pre-sputtering was performed for 5 minutes to remove the oxide layer on the aluminum target surface. Then, a 100 nm thick aluminum layer was sputtered onto one side of the substrate film. After single-sided deposition, the substrate film was flipped, and the same parameters were used to sputter and deposit an aluminum layer on the other side. After sputtering, the deposition chamber was kept under vacuum for 5 minutes, then slowly vented to atmospheric pressure. The sample was removed and placed in the sample chamber of the vacuum evaporator, and the vacuum was evacuated to 2 × 10⁻⁶. -5 Pa, set the evaporation parameters: the evaporation source is 99.99% high-purity aluminum wire, the evaporation temperature is 1200℃, the evaporation rate is 0.5nm / s, and continue evaporation until the total thickness of the double-sided aluminum coating is 2μm. Then stop evaporation, maintain the cavity in a vacuum state for 10min, and then cool to room temperature at a rate of 5℃ / min. Slowly release the gas to normal pressure to obtain a double-sided aluminum base film. (5) Place the double-sided aluminum-coated base film in a magnetic field-assisted heat treatment furnace. Under a nitrogen atmosphere, set the magnetic field strength to 0.5T and the magnetic field direction to be perpendicular to the plane of the base film. Heat the film to 120℃ at a heating rate of 5℃ / min and hold for 30min. Then heat the film to 150℃ at a heating rate of 3℃ / min and hold for 1h. Finally, heat the film to 180℃ at a heating rate of 2℃ / min and hold for 30min. After naturally cooling to room temperature, the thin film aluminum-coated composite current collector is obtained.

[0024] Comparative Example 1 The difference between Comparative Example 1 and Example 3 lies in step (1). Step (1) is changed to: cutting a PET base film with a thickness of 5 μm into a square sample of 10 cm × 10 cm, and performing low-temperature plasma treatment for 2 min to obtain a surface-activated base film. The plasma is oxygen, the gas flow rate is 20 sccm, the reaction chamber pressure is 10 Pa, and the treatment power is 100 W, so as to introduce hydroxyl groups on the surface of the base film. The remaining steps are the same as in Example 3.

[0025] Comparative Example 2 The difference between Comparative Example 2 and Example 3 lies in step (1). Step (1) is changed to: cut a PET base film with a thickness of 5 μm into a square sample of 10 cm × 10 cm, put it into an ultrasonic cleaner, and ultrasonically clean it with anhydrous ethanol and deionized water for 15 min in sequence. The ultrasonic power is 150 W. After cleaning, the base film is placed in an oven at 60 °C and a vacuum degree of -0.09 MPa for 2 h to obtain a surface-activated base film. The remaining steps are the same as in Example 3.

[0026] Comparative Example 3 The difference between Comparative Example 3 and Example 3 lies in step (2). Step (2) is changed to: terephthalaldehyde and DMF are mixed at a mass ratio of 1.5:20, heated to 70°C under a nitrogen atmosphere, stirred at 500 rpm for 2 hours, and then cooled naturally to room temperature. Then, 4,4'-diaminodiphenylmethane diglycidyl ether at 2.5 times the mass of terephthalaldehyde and triethylamine at 0.01 times the total mass of the reaction solution are added. The mixture is stirred at 500 rpm for 30 minutes to obtain the self-made modified solution. The remaining steps are the same as in Example 3.

[0027] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that steps (2) and (3) are removed, and the surface-activated base film from step (1) is used directly to replace the modified base film for step (4). The remaining steps are the same as in Example 3.

[0028] Comparative Example 5 The difference between Comparative Example 5 and Example 3 lies in step (5). Step (5) is changed to: placing the double-sided aluminum-coated base film into a heat treatment furnace, heating it to 120°C at a heating rate of 5°C / min under a nitrogen atmosphere, and holding it at that temperature for 30 min; then heating it to 150°C at a heating rate of 3°C / min and holding it at that temperature for 1 h; finally heating it to 180°C at a heating rate of 2°C / min and holding it at that temperature for 30 min, and then naturally cooling it to room temperature to obtain the thin film aluminum-coated composite current collector. The remaining steps are the same as in Example 3.

[0029] Comparative Example 6 The difference between Comparative Example 6 and Example 3 is that step (5) is omitted, and step (4) is changed to: placing the modified base film into a magnetron sputtering coating machine and evacuating the vacuum in the cavity to a degree of 5 × 10⁻⁶. -4 Pa, sputtering parameters were set as follows: target material was 99.99% high-purity aluminum target, sputtering gas was argon, gas flow rate was 30 sccm, sputtering power was 150 W, substrate temperature was room temperature. Pre-sputtering was performed for 5 minutes to remove the oxide layer on the aluminum target surface. Then, a 100 nm thick aluminum layer was sputtered onto one side of the substrate film. After single-sided deposition, the substrate film was flipped, and the same parameters were used to sputter and deposit an aluminum layer on the other side. After sputtering, the deposition chamber was kept under vacuum for 5 minutes, then slowly vented to atmospheric pressure. The sample was removed and placed in the sample chamber of the vacuum evaporator, and the vacuum was evacuated to 2 × 10⁻⁶. -5 Pa, set the evaporation parameters: the evaporation source is 99.99% high-purity aluminum wire, the evaporation temperature is 1200℃, the evaporation rate is 0.5nm / s, and continue evaporation until the total thickness of the double-sided aluminum coating is 1.5μm. Then stop evaporation, maintain the cavity in a vacuum state for 10min, and then cool to room temperature at a rate of 5℃ / min. Slowly release the gas to normal pressure to obtain a thin film aluminum-coated composite current collector. The remaining steps are the same as in Example 3.

[0030] Example of effect Table 1 below presents the performance analysis results of the thin-film aluminum-coated composite current collectors using Examples 1 to 5 and Comparative Examples 1 to 6 of the present invention.

[0031] Table 1

[0032] A comparison of the experimental data on peel strength between the examples and comparative examples reveals that the present invention first subjectes the base film to low-temperature plasma treatment to introduce hydroxyl groups, then immerses it in a modification solution containing acylhydrazone intermediate A, followed by heating and epoxy ring-opening crosslinking to form a modified base film containing dynamic covalent bonds. Subsequently, micron-scale aluminum layers are deposited on both sides of the base film by magnetron sputtering and vacuum evaporation. Finally, magnetic field-assisted gradient heat treatment optimizes the grain orientation of the aluminum layer and refines the grains. The dynamic covalent bond layer enhances the interfacial bonding strength by forming coordination bonds with aluminum atoms through nitrogen-containing functional groups. The magnetic field assistance and gradient heat treatment synergistically further enhance the interfacial chemical bonding. A comparison of the experimental data on coating peeling between the examples and comparative examples reveals that the reversible dynamic covalent bond layer and crosslinking network in the present invention synergistically endow the base film with good thermal stability and act as a barrier to prevent electrolyte penetration into the base film. A comparison of the experimental data on sheet resistance between the examples and comparative examples reveals that the magnetic field assistance and gradient heat treatment in the present invention synergistically optimize the electrical conductivity and mechanical properties of the aluminum layer.

[0033] 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 its spirit or essential characteristics. 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, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A thin-film aluminum-coated composite current collector, characterized in that, Includes the following steps: (1) Terephthalaldehyde, oxaloyl dihydrazine and organic solvent are mixed in a mass ratio of 1~2:1:

20. Under a nitrogen atmosphere, the mixture is heated to 60~80℃ and stirred at 500rpm for 1~3h. After naturally cooling to room temperature, a solution containing intermediate A is obtained. Then, a crosslinking agent of 2~3 times the mass of terephthalaldehyde and a catalyst of 0.01 times the total mass of the reaction solution are added. The mixture is stirred at 500rpm for 30min to obtain the self-made modified solution. (2) The pretreated polymer base film is subjected to low-temperature plasma treatment for 1~3 min to obtain a surface-activated base film, which is then immersed in a self-made modification solution for 30 min, slowly pulled out, and placed in a vacuum oven at 100℃ for 1 h to obtain a modified base film. (3) After the modified base film is deposited with aluminum layer by magnetron sputtering on both sides, it is then vacuum evaporated until the total thickness of the aluminum layer on both sides is 1~2μm. After evaporation is stopped, the film is cooled to room temperature to obtain a double-sided aluminum base film. The film is then placed in a vertical magnetic field and subjected to gradient heating heat treatment under nitrogen atmosphere. After natural cooling to room temperature, a thin film aluminum composite current collector is obtained.

2. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The organic solvent mentioned in step (1) is DMF.

3. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The crosslinking agent in step (1) is 4,4'-diaminodiphenylmethane diglycidyl ether.

4. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The catalyst mentioned in step (1) is triethylamine.

5. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The polymer base film in step (2) is a PET film with a thickness of 5 μm.

6. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The plasma mentioned in step (2) is oxygen.

7. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The slow lifting speed described in step (2) is 2 mm / s.

8. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The thickness of the deposited aluminum layer in step (3) is 100 nm.

9. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The vertical magnetic field strength in step (3) is 0.5T.

10. The thin-film aluminum-coated composite current collector according to claim 1, characterized in that, The gradient heating process in step (3) is as follows: heat up to 120°C at a heating rate of 5°C / min and hold for 30 min; then heat up to 150°C at a heating rate of 3°C / min and hold for 1 h; finally heat up to 180°C at a heating rate of 2°C / min and hold for 30 min.

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