A multilayer aluminized composite current collector and a method for preparing the same

Abstract

This invention discloses a multilayer aluminum-coated composite current collector and its preparation method, relating to the field of composite current collector technology. The invention first coats a PET substrate surface with polyurethane containing silver nanowires. The silver nanowires construct a three-dimensional conductive pathway within the polyurethane, reducing sheet resistance. Then, oxygen plasma treatment is used to introduce oxygen-containing functional groups into the coating, which can act as highly active chemical sites, reacting chemically with aluminum atoms / ions in the sputtering environment. Next, a first layer of alumina is prepared by magnetron sputtering aluminum in an oxygen-containing atmosphere, embedding the silver nanowires into this first alumina film. Then, a second layer of aluminum nitride is prepared by magnetron sputtering aluminum in a nitrogen atmosphere. The thermal expansion coefficient of aluminum nitride is between that of alumina and aluminum, avoiding excessive shear stress between layers that could lead to delamination. The two layers of alumina / aluminum nitride form a multi-element aluminum layer, which effectively prevents lithium dendrite penetration. Finally, metallic aluminum is vapor-deposited onto the surface of the multi-element aluminum layer to ensure efficient conductivity of the current collector.

Description

Technical Field

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

[0002] In pursuit of higher energy density and safety, the lithium battery industry has developed an innovative technology called composite current collector. It abandons the heavy pure metal (copper / aluminum) current collector and instead employs a "sandwich" structure: using a lightweight polymer material (such as PET, PP, PI) as the base film, with metal layers deposited on both sides. This design successfully achieves weight reduction and optimizes conductivity and thermal stability.

[0003] However, innovation hides serious challenges. Because the base film of the composite current collector is a non-polar polymer material, its properties differ greatly from those of metal materials, resulting in weak bonding between the base film and the metal film. During subsequent electrolyte immersion, defects such as metal film detachment, cracking, and bulging are easily caused, leading to lithium battery failure, short lifespan, and even more serious battery safety issues. Summary of the Invention

[0004] The purpose of this invention is to provide a multilayer aluminum-plated 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 multi-layer aluminum-plated composite current collector, wherein the multi-layer aluminum-plated composite current collector is prepared by first coating a coating containing silver nanowires on both sides of a substrate, activating it by plasma, then magnetron sputtering a multi-element aluminum layer on the coating, and finally evaporating aluminum on the multi-element aluminum layer. The multi-element aluminum layer comprises a first aluminum oxide film and a second aluminum nitride film obtained by magnetron sputtering aluminum in an oxygen atmosphere and a nitrogen atmosphere, respectively.

[0006] Furthermore, the substrate is PET.

[0007] Furthermore, the coating comprises polyurethane and N,N-dimethylformamide solvent.

[0008] Furthermore, a method for preparing a multilayer aluminum-plated composite current collector includes the following preparation steps: (1) Select a PET substrate with a thickness of 3~12μm, remove oil and other impurities attached to the outer surface after cleaning process, coat the cleaned surface with a coating containing silver nanowires, dry at 100℃ for 30s, and treat with plasma to obtain a pretreated substrate. (2) The pretreated substrate is placed in the magnetron sputtering chamber, and an oxygen-containing atmosphere is introduced. An alumina coating is formed on the surface of the pretreated substrate by magnetron sputtering to obtain a substrate with an alumina film. (3) Place the substrate with aluminum oxide film in the magnetron sputtering chamber, introduce nitrogen gas, and form an aluminum nitride layer on the surface of the substrate with aluminum oxide film by magnetron sputtering to obtain a substrate with a multi-element aluminum layer. (4) Place the substrate with the multi-element aluminum layer in the coating equipment and deposit the aluminum layer onto the surface of the multi-element aluminum layer by vacuum evaporation until the aluminum layer of the target thickness is obtained, thus producing a multi-layer aluminum composite current collector.

[0009] Furthermore, in step (1), the coating comprises silver nanowires, polyurethane, and N,N-dimethylformamide solvent in a mass ratio of 2:5:93, and the coating thickness is 15~20nm.

[0010] Furthermore, in step (1), the atmosphere for plasma treatment is an argon / oxygen mixture with a volume ratio of 5:1, the power is 5~30W, and the time is 1~3min.

[0011] Furthermore, the process parameters for magnetron sputtering in step (2) are as follows: the gas flow rate of the oxygen-containing atmosphere is 40~60 mL / min, the volume ratio of oxygen to inert gas in the oxygen-containing atmosphere is 2:1, and the sputtering power density is 30~50 W / cm³. 2 The vacuum degree is 4×10 -4 ~5×10 -4 Pa.

[0012] Furthermore, the process parameters for magnetron sputtering in step (3) are: nitrogen gas flow rate of 40~60 mL / min, sputtering power density of 30~50 W / cm³. 2 The vacuum degree is 4×10 -4 ~5×10 -4 Pa.

[0013] Furthermore, the process parameters for vacuum evaporation in step (4) are: evaporation temperature of 700℃, vacuum degree of 0.002~0.005Pa, and coating speed of 80~120m / min.

[0014] Furthermore, in step (4), the target thickness is 100 nm to 5000 nm.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention prepares a multilayer aluminum-coated composite current collector by first coating a PET substrate with polyurethane containing silver nanowires, then magnetron sputtering a multi-element aluminum layer on the polyurethane, and finally evaporating aluminum on the multi-element aluminum layer. This effectively enhances the bonding force between the PET substrate and the aluminum film, thereby improving the battery cycle life and safety performance.

[0016] In the preparation of the composite current collector, a polyurethane coating containing silver nanowires is first coated on the surface of a PET substrate. The silver nanowires construct three-dimensional conductive pathways within the polyurethane, reducing the surface resistivity. Then, oxygen plasma treatment is used to introduce oxygen-containing functional groups into the coating. These functional groups act as highly active chemical sites, reacting with aluminum atoms / ions in the sputtering environment to form strong chemical bonds, thereby inducing the nucleation and growth of the alumina film and enhancing interfacial adhesion. Finally, the first alumina film is prepared by magnetron sputtering aluminum in an oxygen-containing atmosphere, and the silver nanowires are then... The first layer of aluminum oxide film is embedded in the first layer of aluminum oxide film. Then, aluminum is magnetron sputtered in a nitrogen atmosphere to prepare a second layer of aluminum nitride film. The thermal expansion coefficient of aluminum nitride is between that of aluminum oxide and aluminum, which suppresses the volume expansion of the current collector during charging and discharging and avoids excessive shear stress between layers that could lead to delamination. The two layers of aluminum oxide / aluminum nitride form a multi-element aluminum layer, which can effectively prevent lithium dendrite penetration and improve the safety performance of the battery. Finally, metallic aluminum is evaporated on the surface of the multi-element aluminum layer to prepare a multi-layer aluminum-plated composite current collector, which provides a low-resistance electron transport channel and ensures efficient conductivity of the current collector.

[0017] The multilayer aluminum-plated composite current collector prepared by this invention has a conductivity of up to 3.9 × 10⁻⁶. 6 With a surface energy of 72 dynes / cm and an internal resistance as low as 20mΩ, the battery retains a capacity of up to 93% after 1000 cycles. This invention, through multi-layer structural design and key process control, not only enhances the bonding force between the substrate and the aluminum layer, but also significantly improves the conductivity, interface stability, and anti-dendrying ability of the current collector, effectively extending the battery's cycle life and improving its safety. Detailed Implementation

[0018] 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.

[0019] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The test methods for various indicators of the multilayer aluminum-plated composite current collector prepared in the following embodiments are as follows: Example 1

[0020] A method for preparing a multilayer aluminum-plated composite current collector includes the following preparation steps: (1) Select a PET substrate with a thickness of 3μm, remove oil and other impurities attached to the outer surface after cleaning, coat the cleaned surface with a coating containing silver nanowires, dry at 100℃ for 30s, and treat with plasma to obtain a pretreated substrate; the coating includes silver nanowires, polyurethane and N,N-dimethylformamide solvent in a mass ratio of 2:5:93, and the coating thickness is 15nm; the atmosphere of the plasma treatment is an argon / oxygen mixture with a volume ratio of 5:1, the power is 5W, and the time is 1min; (2) The pretreated substrate is placed in a magnetron sputtering chamber, and an oxygen-containing atmosphere is introduced. An alumina coating is formed on the surface of the pretreated substrate by magnetron sputtering. The coating thickness is 0.1 nm, and an alumina-coated substrate is obtained. The process parameters of the magnetron sputtering are: the gas flow rate of the oxygen-containing atmosphere is 40 mL / min, the volume ratio of oxygen to inert gas in the oxygen-containing atmosphere is 2:1, and the sputtering power density is 30 W / cm³. 2 The vacuum degree is 4×10 -4 Pa; (3) The substrate with the alumina film is placed in the magnetron sputtering chamber, nitrogen gas is introduced, and an aluminum nitride layer is formed on the surface of the substrate with the alumina film by magnetron sputtering. The coating thickness is 0.1 nm, and a substrate with a multi-element aluminum layer is obtained. The process parameters of the magnetron sputtering are: nitrogen gas flow rate of 40 mL / min, sputtering power density of 30 W / cm. 2 The vacuum degree is 4×10 -4 Pa; (4) The substrate with the multi-element aluminum layer is placed in the coating equipment, and the aluminum layer is deposited on the surface of the multi-element aluminum layer by vacuum evaporation until the aluminum layer of the target thickness is obtained, so as to make a multi-layer aluminum composite current collector; the process parameters of the vacuum evaporation are: evaporation temperature is 700℃, vacuum degree is 0.002Pa, coating speed is 80m / min; the target thickness is 100nm. Example 2

[0021] A method for preparing a multilayer aluminum-plated composite current collector includes the following preparation steps: (1) Select a PET substrate with a thickness of 6μm, remove oil and other impurities attached to the outer surface after cleaning, coat the cleaned surface with a coating containing silver nanowires, dry at 100℃ for 30s, and treat with plasma to obtain a pretreated substrate; the coating includes silver nanowires, polyurethane and N,N-dimethylformamide solvent in a mass ratio of 2:5:93, and the coating thickness is 16nm; the atmosphere of the plasma treatment is an argon / oxygen mixture with a volume ratio of 5:1, the power is 15W, and the time is 2min; (2) The pretreated substrate is placed in a magnetron sputtering chamber, and an oxygen-containing atmosphere is introduced. An alumina coating is formed on the surface of the pretreated substrate by magnetron sputtering with a coating thickness of 0.4 nm, thus obtaining a substrate with an alumina film. The process parameters of the magnetron sputtering are as follows: the gas flow rate of the oxygen-containing atmosphere is 45 mL / min, the volume ratio of oxygen to inert gas in the oxygen-containing atmosphere is 2:1, and the sputtering power density is 35 W / cm³. 2 The vacuum degree is 4.2 × 10⁻⁶. -4 Pa; (3) The substrate with the alumina film is placed in the magnetron sputtering chamber, nitrogen gas is introduced, and an aluminum nitride layer is formed on the surface of the substrate with the alumina film by magnetron sputtering. The coating thickness is 0.4 nm, and a substrate with a multi-element aluminum layer is obtained. The process parameters of the magnetron sputtering are: nitrogen gas flow rate of 45 mL / min, sputtering power density of 35 W / cm. 2 The vacuum degree is 4.5 × 10⁻⁶. -4 Pa; (4) The substrate with the multi-element aluminum layer is placed in the coating equipment, and the aluminum layer is deposited on the surface of the multi-element aluminum layer by vacuum evaporation until the aluminum layer of the target thickness is obtained, so as to make a multi-layer aluminum composite current collector; the process parameters of the vacuum evaporation are: evaporation temperature is 700℃, vacuum degree is 0.003Pa, coating speed is 90m / min; the target thickness is 1000nm. Example 3

[0022] A method for preparing a multilayer aluminum-plated composite current collector includes the following preparation steps: (1) Select a PET substrate with a thickness of 8μm, remove oil and other impurities attached to the outer surface after cleaning, coat the cleaned surface with a coating containing silver nanowires, dry at 100℃ for 30s, and treat with plasma to obtain a pretreated substrate; the coating includes silver nanowires, polyurethane and N,N-dimethylformamide solvent in a mass ratio of 2:5:93, and the coating thickness is 18nm; the atmosphere of the plasma treatment is an argon / oxygen mixture with a volume ratio of 5:1, the power is 20W, and the time is 2min; (2) The pretreated substrate is placed in a magnetron sputtering chamber, and an oxygen-containing atmosphere is introduced. An alumina coating is formed on the surface of the pretreated substrate by magnetron sputtering. The coating thickness is 0.6 nm, and an alumina-coated substrate is obtained. The process parameters of the magnetron sputtering are: the gas flow rate of the oxygen-containing atmosphere is 50 mL / min, the volume ratio of oxygen to inert gas in the oxygen-containing atmosphere is 2:1, and the sputtering power density is 40 W / cm. 2 The vacuum degree is 4.5 × 10⁻⁶. -4 Pa; (3) The substrate with the alumina film is placed in the magnetron sputtering chamber, nitrogen gas is introduced, and an aluminum nitride layer is formed on the surface of the substrate with the alumina film by magnetron sputtering. The coating thickness is 0.6 nm, and a substrate with a multi-element aluminum layer is obtained. The process parameters of the magnetron sputtering are: nitrogen gas flow rate of 50 mL / min, sputtering power density of 40 W / cm. 2 The vacuum degree is 4.5 × 10⁻⁶. -4 Pa; (4) The substrate with the multi-element aluminum layer is placed in the coating equipment, and the aluminum layer is deposited on the surface of the multi-element aluminum layer by vacuum evaporation until the aluminum layer of the target thickness is obtained, so as to make a multi-layer aluminum composite current collector; the process parameters of the vacuum evaporation are: evaporation temperature of 700℃, vacuum degree of 0.004Pa, coating speed of 100m / min; the target thickness is 2500nm. Example 4

[0023] A method for preparing a multilayer aluminum-plated composite current collector includes the following preparation steps: (1) Select a PET substrate with a thickness of 10 μm, remove oil and other impurities attached to the outer surface after cleaning, coat the cleaned surface with a coating containing silver nanowires, dry at 100°C for 30 s, and treat with plasma to obtain a pretreated substrate; the coating includes silver nanowires, polyurethane and N,N-dimethylformamide solvent in a mass ratio of 2:5:93, and the coating thickness is 18 nm; the atmosphere of the plasma treatment is an argon / oxygen mixture with a volume ratio of 5:1, the power is 25 W, and the time is 3 min; (2) The pretreated substrate is placed in a magnetron sputtering chamber, and an oxygen-containing atmosphere is introduced. An alumina coating is formed on the surface of the pretreated substrate by magnetron sputtering with a coating thickness of 0.8 nm, thus obtaining a substrate with an alumina film. The process parameters of the magnetron sputtering are: the gas flow rate of the oxygen-containing atmosphere is 55 mL / min, the volume ratio of oxygen to inert gas in the oxygen-containing atmosphere is 2:1, and the sputtering power density is 45 W / cm². 2 The vacuum degree is 4.8 × 10⁻⁶. -4 Pa; (3) The substrate with the alumina film is placed in the magnetron sputtering chamber, nitrogen gas is introduced, and an aluminum nitride layer is formed on the surface of the substrate with the alumina film by magnetron sputtering. The coating thickness is 0.1 nm to 1 nm, and a substrate with a multi-element aluminum layer is obtained. The process parameters of the magnetron sputtering are: nitrogen gas flow rate of 55 mL / min, sputtering power density of 45 W / cm. 2 The vacuum degree is 4.8 × 10⁻⁶. -4 Pa; (4) The substrate with the multi-element aluminum layer is placed in the coating equipment, and the aluminum layer is deposited on the surface of the multi-element aluminum layer by vacuum evaporation until the aluminum layer of the target thickness is obtained, so as to make a multi-layer aluminum composite current collector; the process parameters of the vacuum evaporation are: evaporation temperature of 700℃, vacuum degree of 0.004Pa, coating speed of 110m / min; the target thickness is 3000nm. Example 5

[0024] A method for preparing a multilayer aluminum-plated composite current collector includes the following preparation steps: (1) Select a PET substrate with a thickness of 12μm, remove oil and other impurities attached to the outer surface after cleaning, coat the cleaned surface with a coating containing silver nanowires, dry at 100℃ for 30s, and treat with plasma to obtain a pretreated substrate; the coating includes silver nanowires, polyurethane and N,N-dimethylformamide solvent in a mass ratio of 2:5:93, and the coating thickness is 20nm; the atmosphere of the plasma treatment is an argon / oxygen mixture with a volume ratio of 5:1, the power is 30W, and the time is 3min. (2) The pretreated substrate is placed in a magnetron sputtering chamber, and an oxygen-containing atmosphere is introduced. An alumina coating is formed on the surface of the pretreated substrate by magnetron sputtering. The coating thickness is 1 nm, and an alumina-coated substrate is obtained. The process parameters of the magnetron sputtering are: the gas flow rate of the oxygen-containing atmosphere is 60 mL / min, the volume ratio of oxygen to inert gas in the oxygen-containing atmosphere is 2:1, and the sputtering power density is 50 W / cm. 2 The vacuum degree is 5×10 -4 Pa; (3) The substrate with the alumina film is placed in the magnetron sputtering chamber, nitrogen gas is introduced, and an aluminum nitride layer is formed on the surface of the substrate with the alumina film by magnetron sputtering. The coating thickness is 1 nm, and a substrate with a multi-element aluminum layer is obtained. The process parameters of the magnetron sputtering are: nitrogen gas flow rate of 60 mL / min, sputtering power density of 50 W / cm. 2 The vacuum degree is 5×10 -4 Pa; (4) The substrate with the multi-element aluminum layer is placed in the coating equipment, and the aluminum layer is deposited on the surface of the multi-element aluminum layer by vacuum evaporation until the aluminum layer of the target thickness is obtained, so as to make a multi-layer aluminum composite current collector; the process parameters of the vacuum evaporation are: evaporation temperature is 700℃, vacuum degree is 0.005Pa, coating speed is 120m / min; the target thickness is 5000nm.

[0025] Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that step (1) is different. Step (1) is changed to: select a PET substrate with a thickness of 8μm, and remove oil stains and other impurities attached to the outer surface after cleaning process; the rest of the steps are the same as in Example 3.

[0026] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that step (2) is omitted, and the substrate for the alumina film in step (3) is replaced with a pretreated substrate; the remaining steps are the same as in Example 3.

[0027] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that step (3) is omitted, and the substrate in step (4) with the multi-element aluminum layer is replaced with a substrate with an aluminum oxide film; the remaining steps are the same as in Example 3.

[0028] The performance of the composite current collectors obtained in the above embodiments and comparative examples was tested, and the test results are shown in Table 1 below. A four-probe tester was used to test the conductivity of the single-sided aluminum plating layer, and a dyne pen was used to test the surface energy of the aluminum plating layer. The composite current collector was combined with the positive electrode active material to obtain a positive electrode sheet, which was then assembled with a negative electrode sheet, electrolyte, and separator to form a lithium battery. The internal resistance of the lithium battery (capacity 50Ah) and the capacity retention rate after 1000 cycles were tested.

[0029] Table 1. Comparison of physical properties of composite current collectors in the examples and comparative examples.

[0030] A comparison of experimental data from the examples and comparative examples reveals that, in the preparation process of the composite current collector, the present invention first coats a polyurethane coating containing silver nanowires onto the surface of a PET substrate. The silver nanowires construct a three-dimensional conductive pathway within the polyurethane, reducing the surface resistivity. Then, oxygen plasma treatment is used to introduce oxygen-containing functional groups into the coating. These functional groups can act as highly active chemical sites, reacting chemically with aluminum atoms / ions in the sputtering environment to form strong chemical bonds, thereby inducing the nucleation and growth of the alumina film and enhancing interfacial adhesion. Finally, magnetron sputtering is performed in an oxygen-containing atmosphere. The process involves: first, preparing an aluminum oxide film by magnetron sputtering, and then embedding silver nanowires into the first aluminum oxide film; second, preparing a second aluminum nitride film by magnetron sputtering aluminum in a nitrogen atmosphere. The thermal expansion coefficient of aluminum nitride is between that of aluminum oxide and aluminum, which suppresses the volume expansion of the current collector during charging and discharging, and avoids excessive shear stress between layers that could lead to delamination. The two aluminum oxide / aluminum nitride layers form a multi-element aluminum layer, which can effectively prevent lithium dendrite penetration; finally, multi-layer aluminum-plated composite current collector is prepared by evaporating metallic aluminum on the surface of the multi-element aluminum layer, providing a low-resistance electron transport channel and ensuring efficient conductivity of the current collector.

[0031] 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 multilayer aluminum-plated composite current collector, characterized in that, The multi-layer aluminum-plated composite current collector is prepared by first coating the two sides of the substrate with a coating containing silver nanowires, activating it with plasma, then magnetron sputtering a multi-element aluminum layer on the coating, and finally evaporating aluminum on the multi-element aluminum layer. The multi-element aluminum layer comprises a first aluminum oxide film and a second aluminum nitride film obtained by magnetron sputtering aluminum in an oxygen atmosphere and a nitrogen atmosphere, respectively.

2. The multilayer aluminum-plated composite current collector according to claim 1, characterized in that, The substrate is PET.

3. The multilayer aluminum-plated composite current collector according to claim 2, characterized in that, The coating comprises polyurethane and N,N-dimethylformamide solvent.

4. A method for preparing a multilayer aluminum-plated composite current collector, characterized in that, The preparation steps include the following: (1) Select a PET substrate with a thickness of 3~12μm, remove oil and other impurities attached to the outer surface after cleaning process, coat the cleaned surface with a coating containing silver nanowires, dry at 100℃ for 30s, and treat with oxygen plasma to obtain a pretreated substrate. (2) The pretreated substrate is placed in the magnetron sputtering chamber, and an oxygen-containing atmosphere is introduced. An alumina coating is formed on the surface of the pretreated substrate by magnetron sputtering to obtain a substrate with an alumina film. (3) Place the substrate with aluminum oxide film in the magnetron sputtering chamber, introduce nitrogen gas, and form an aluminum nitride layer on the surface of the substrate with aluminum oxide film by magnetron sputtering to obtain a substrate with a multi-element aluminum layer. (4) Place the substrate with the multi-element aluminum layer in the coating equipment and deposit the aluminum layer onto the surface of the multi-element aluminum layer by vacuum evaporation until the aluminum layer of the target thickness is obtained, thus producing a multi-layer aluminum composite current collector.

5. The method for preparing a multilayer aluminum-plated composite current collector according to claim 4, characterized in that, The coating in step (1) includes silver nanowires, polyurethane and N,N-dimethylformamide solvent in a mass ratio of 2:5:93, and the coating thickness is 15~20nm.

6. The method for preparing a multilayer aluminum-plated composite current collector according to claim 4, characterized in that, In step (1), the plasma treatment atmosphere is an argon / oxygen mixture with a volume ratio of 5:1, the power is 5~30W, and the time is 1~3min.

7. The method for preparing a multilayer aluminum-plated composite current collector according to claim 4, characterized in that, The process parameters for magnetron sputtering in step (2) are as follows: the gas flow rate of the oxygen-containing atmosphere is 40~60 mL / min, the volume ratio of oxygen to inert gas in the oxygen-containing atmosphere is 2:1, and the sputtering power density is 30~50 W / cm³. 2 The vacuum degree is 4×10 -4 ~5×10 -4 Pa.

8. The method for preparing a multilayer aluminum-plated composite current collector according to claim 4, characterized in that, The process parameters for magnetron sputtering in step (3) are: nitrogen gas flow rate of 40~60 mL / min, sputtering power density of 30~50 W / cm³. 2 The vacuum degree is 4×10 -4 ~5×10 -4 Pa.

9. The method for preparing a multilayer aluminum-plated composite current collector according to claim 4, characterized in that, The process parameters for vacuum evaporation in step (4) are: evaporation temperature of 700℃, vacuum degree of 0.002~0.005Pa, and coating speed of 80~120m / min.

10. The method for preparing a multilayer aluminum-plated composite current collector according to claim 4, characterized in that, The target thickness in step (4) is 100nm to 5000nm.

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