Multilayer functional copper current collector and preparation method thereof

Abstract

The invention discloses a multi-layer functional copper current collector and a preparation method thereof, and relates to the technical field of functional current collectors. The preparation method comprises the following steps: carrying out plasma cleaning on a macromolecular base membrane, and then immersing into a NaOH solution for activation; depositing copper through magnetron sputtering to form a copper seed layer so as to obtain a pretreated functional current collector; immersing the pretreated functional current collector into pyrophosphate copper plating liquid, adjusting pH, depositing pyrophosphate copper to form a pyrophosphate copper layer, and drying to obtain a pyrophosphate copper functional current collector; immersing the pyrophosphate copper functional current collector into an acidic sulfate copper plating solution to deposit copper, and thickening a copper layer to obtain a multi-layer functional copper current collector; the pyrophosphate copper transition layer is introduced between the magnetron sputtering seed layer and the acid sulfate copper plating solution thickening layer, so that the interface structure and the deposition dynamics are optimized, and the performance and the preparation efficiency of the composite copper current collector are comprehensively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional current collector, in particular to a multi-layer functional copper current collector and a preparation method thereof. BACKGROUND

[0002] As a new generation of battery key material, the functional current collector realizes lighter weight and thinner thickness than traditional metal foil through the functional metal layer on the surface of the lightweight polymer substrate, and has better safety performance and cost advantage. The functional copper current collector as an innovative scheme of lithium battery negative electrode current collector usually adopts a sandwich structure of "copper layer-polymer layer-copper layer", and the middle layer is a polymer film made of organic PET, PP, PI and the like. Through a two-step method of "magnetron sputtering + acidic water plating", a thin copper layer is first sputtered on both sides of the base film, and then the copper layer is thickened to about 1 μm through the water plating process.

[0003] In the prior art, the two-step method of "magnetron sputtering + acidic water plating" has the problems of high investment of magnetron sputtering equipment, "cold welding" defects caused by insufficient adhesion between the seed layer and the plated layer, and corrosion risk of the acidic plating solution to the polymer substrate. Especially under the background of strict environmental regulations, the traditional cyanide copper plating process has been restricted, and the industry urgently needs to develop a new pre-plating technology scheme with environmental friendliness and high adhesion. Therefore, the present application provides a multi-layer functional copper current collector and a preparation method thereof to solve the above technical problems. SUMMARY

[0004] The present application aims to provide a multi-layer functional copper current collector and a preparation method thereof to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: A multi-layer functional copper current collector, comprising the following structure: a polymer base film layer, a copper seed layer, a cuprous copper layer, and a copper layer, the copper layer is arranged on the upper surface and the lower surface of the polymer base film layer, the cuprous copper layer is arranged between the copper seed layer and the copper layer, and the copper seed layer is arranged between the polymer base film layer and the cuprous copper layer.

[0006] Further, the thickness of the polymer base film layer is 3-8 μm.

[0007] Further, the polymer base film is any one of PET (polyethylene terephthalate) and PP (polypropylene).

[0008] A preparation method of a multi-layer functional copper current collector, comprising the following steps: S1: magnetron sputtering deposition of copper on the upper surface and the lower surface of the polymer base film to form a copper seed layer, and obtain a pretreated functional current collector; S2: Immerse the pretreated functional current collector in a pyrophosphate copper plating solution, adjust the pH, deposit pyrophosphate copper to form a pyrophosphate copper layer, and dry to obtain a pyrophosphate copper functional current collector. S3: Immerse the pyrometallurgical copper current collector in an acidic sulfate copper plating solution to deposit copper, thicken the copper layer, and obtain a multilayer functional copper current collector.

[0009] Furthermore, the polymer base film undergoes plasma cleaning before use. In the plasma cleaning process, the power is 5~10kW and an argon atmosphere is used.

[0010] Furthermore, before magnetron sputtering, the polymer base film is immersed in an alkaline solution for weak alkaline etching to further activate the surface.

[0011] Furthermore, the weak alkaline etching process involves immersing the polymer base film in a 5-10 wt% NaOH solution at 40-50°C for 30-40 seconds.

[0012] Furthermore, the preparation process of the copper seed layer is as follows: The polymer base film is loaded into a magnetron sputtering device, a vacuum is drawn, and argon gas is introduced as the working gas at a pressure of 0.5~1.0 Pa. A pure copper target is used, and copper is deposited on the upper and lower surfaces of the polymer base film by magnetron sputtering under the conditions of DC power of 5~8 kW and polymer base film temperature of 60~80℃ to form a copper seed layer.

[0013] Furthermore, the thickness of the copper seed layer is 20~50nm.

[0014] Furthermore, in step S3, the thickness of the copper plating layer is 0.2~0.5μm.

[0015] Furthermore, in step S3, the pH adjustment process is as follows: the pH is adjusted to 8.5~9.0 using ammonia or potassium hydroxide solution.

[0016] Furthermore, in step S3, the temperature for depositing copper plating is controlled at 50~55℃, and a pulsed current is used with a current density of 0.5~1.5A / dm³. 2 Duty cycle 30%, frequency 1000Hz, deposition time 3~8min.

[0017] Furthermore, in step S4, the copper layer is thickened to 0.8~1.2μm.

[0018] Furthermore, the pyrophosphate copper plating solution comprises the following components by mass: 60-80 g / L copper pyrophosphate, 300-400 g / L potassium pyrophosphate, 20-30 g / L potassium nitrate, 30-40 g / L ammonium citrate, 0.1-0.3 g / L 2-mercaptobenzimidazole, and 0.2-0.5 g / L EDTA.

[0019] Furthermore, the acidic sulfate copper plating solution comprises the following components by mass: 250-260 g / L copper sulfate (CuSO4·5H2O), 50-60 g / L sulfuric acid (H2SO4), and 60-80 ppm chloride ions (Cl). - ), 0.5-0.8% of additives.

[0020] Furthermore, the chloride ions are derived from either high-purity hydrochloric acid or sodium chloride.

[0021] Furthermore, the additive includes the following components: polyether carrier, organosulfur compound brightener, and nitrogen-containing heterocyclic leveling agent.

[0022] In the above technical solution, the present invention introduces a coke transition layer between the magnetron sputtering seed layer and the thickened layer of the acidic sulfate copper plating solution, thereby optimizing the interface structure and deposition kinetics and comprehensively improving the performance and preparation efficiency of the composite copper current collector.

[0023] Furthermore, the polymer base film undergoes surface treatment, the specific process of which is as follows: Step 1: Add lignin to anhydrous ethanol, disperse, then add tetraethyl orthosilicate, adjust the pH to 8-10, stir evenly to obtain composite lignin; Step 2: Add the composite lignin to the dopamine hydrochloride solution, disperse, heat to react, centrifuge, and dry to obtain the modified organic filler; Step 3: Mix the modified organic filler with carboxylated carbon nanotubes, add anhydrous ethanol, disperse, then add polyacrylic acid, acetylacetonate diol, and sodium carboxymethyl cellulose, stir evenly to obtain the modified slurry; Step 4: Coat the upper and lower surfaces of the polymer base film with the modified slurry, and dry to obtain the composite polymer base film.

[0024] Furthermore, in step four, the coating amount of the modified slurry is 100~150g / m². 2 .

[0025] In the above technical solution, this invention enhances the chemical corrosion resistance of the polymer base film by surface treatment, thus solving the risk of corrosion of the base film by electroplating solution during subsequent copper deposition. Adding modified organic fillers to the modified slurry effectively enhances the mechanical properties and corrosion resistance of the polymer base film. Compared to conventional organic fillers such as benzotriazole and polyaniline, lignin is a greener, more environmentally friendly, non-toxic, and harmless organic filler. Lignin is a natural polyphenolic wood fiber derivative, a highly heterogeneous polymer composed of three different phenylpropane units. By combining lignin with silica, the high specific surface area of ​​amorphous silica significantly increases the corrosion and wear resistance of lignin, thereby improving the chemical corrosion resistance of the polymer base film in the electrolyte. Adding carboxylated carbon nanotubes increases interfacial compatibility with the copper seed layer, reduces thermal stress, and the surface carboxyl groups improve the dispersibility of the modified organic filler in the slurry, increasing the uniformity of the coating and avoiding the risk of delamination. Polyacrylic acid acts as a binder, enhancing the bonding strength between the modified slurry and the copper layer. Alkyne glycol and sodium carboxymethyl cellulose adjust the wettability and viscosity of the slurry.

[0026] Furthermore, the mass ratio of lignin, tetraethyl orthosilicate, and anhydrous ethanol is 1:(0.1~0.3):(10~20).

[0027] Furthermore, the mass ratio of the composite lignin to the dopamine hydrochloride solution is 1:(5~10).

[0028] Furthermore, the concentration of the dopamine hydrochloride solution is 18-22 mM.

[0029] Furthermore, the modified slurry comprises the following components by weight: 10-20 parts of modified organic filler, 1-5 parts of carboxylated carbon nanotubes, 5-15 parts of polyacrylic acid, 0.5-2 parts of acetylacetonate diol, and 1-3 parts of sodium carboxymethyl cellulose.

[0030] Furthermore, in step three, the solid content of the modified slurry is 10-30%.

[0031] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention optimizes the interface structure and deposition kinetics by depositing copper layers on the upper and lower surfaces of a polymer base film and introducing a pyrocopper transition layer between the magnetron sputtering seed layer and the thickened layer of the acidic sulfate copper plating solution, thereby comprehensively improving the performance and preparation efficiency of the composite copper current collector.

[0032] 2. This invention enhances the chemical corrosion resistance of the polymer base film by surface treatment and coating it with a modified slurry.

[0033] 3. This invention effectively enhances the mechanical properties and corrosion resistance of polymer base films by adding modified organic fillers to modified slurries. By combining lignin with silica, the high specific surface area of ​​amorphous silica significantly increases the corrosion and wear resistance of lignin, thereby improving the chemical corrosion resistance of the polymer base film layer in the electrolyte. By adding carboxylated carbon nanotubes, the interfacial compatibility with the copper seed layer is increased, thermal stress is reduced, and the surface carboxyl groups can improve the dispersibility of modified organic fillers in the slurry, increase the uniformity of the coating layer, and avoid the risk of delamination. Detailed Implementation

[0034] 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.

[0035] In the following specific implementation, PET (polyethylene terephthalate), 4.5μm thick, DuPont, USA, model 530; PP (polypropylene), 4.5μm thick, Toray Industries, Japan; Sodium carboxymethyl cellulose, model DSL-1220; Carboxylated carbon nanotubes, with an average particle size of 40 nm; The acetylenic diol is 2,7-dimethyl-3,5-octadiyne-2,7-diol, CAS: 5929-72-6; The concentration of dopamine hydrochloride solution is 20 mM; The additives include the following components: polyether carriers, organosulfur compound brighteners, and nitrogen-containing heterocyclic leveling agents; Polyether carrier, model MT-480; The brightener is sodium 3-mercapto-1-propanesulfonate, CAS: 17636-10-1; The leveling agent is N,N-diethylthiourea, CAS:105-55-5. Example 1:

[0036] A method for preparing a multilayer functional copper current collector includes the following steps: S1: The PET film is plasma cleaned and then immersed in a 5wt% NaOH solution for activation to obtain a pretreated PET film; S2: Copper is deposited by magnetron sputtering on the upper and lower surfaces of the pretreated PET film to form a copper seed layer, thus obtaining the pretreated functional current collector; the magnetron sputtering process parameters are: vacuum degree 2×10 -5mbar, argon atmosphere, working pressure 0.5Pa, copper target purity 99.99%, DC power 8kW, temperature 80℃, copper seed layer thickness 30nm; S3: Immerse the pretreated functional current collector in a pyrophosphate copper plating solution, adjust the pH to 8.8 with 25 wt% ammonia, deposit pyrophosphate copper to form a pyrophosphate copper layer, and dry to obtain the pyrophosphate copper functional current collector; the process parameters for depositing pyrophosphate copper are: temperature 52℃, pulse power supply, and forward current density 1.2 A / dm³. 2 Reverse current density 0.4 A / dm 2 A pyrocopper functional current collector with a thickness of 0.3 μm was obtained by using a frequency of 1000 Hz, a duty cycle of 30%, and a time of 5 min. S4: The pyrometallurgical copper current collector is immersed in an acidic sulfate copper plating solution to deposit copper, thickening the copper layer to 1 μm to obtain a multilayer functional copper current collector; the current density is 3 A / dm. 2 Temperature 25℃, time 8min, cathode movement during electroplating, frequency 15 times / min, amplitude 50mm; The thickness of the PET base film is 4.5 μm; The copper pyrophosphate plating solution comprises the following components by mass: 70 g / L copper pyrophosphate, 350 g / L potassium pyrophosphate, 25 g / L potassium nitrate, 35 g / L ammonium citrate, 0.1 g / L 2-mercaptobenzimidazole, and 0.2 g / L EDTA (ethylenediaminetetraacetic acid). The acidic sulfate copper plating solution comprises the following components by mass: 250 g / L copper sulfate (CuSO4·5H2O), 50 g / L sulfuric acid (H2SO4), and 60 ppm chloride ions (Cl). - ), 0.5% additives; Chloride ions are derived from sodium chloride, with a purity of 99.995%. Example 2:

[0037] This embodiment provides a method for preparing a multilayer functional copper current collector, using PP as the polymer base film, and the magnetron sputtering process conditions are: sputtering temperature 55℃, sputtering power 5kW, and copper seed layer thickness 25nm; The copper pyrophosphate plating solution comprises the following components by mass: 70 g / L copper pyrophosphate, 380 g / L potassium pyrophosphate, 25 g / L potassium nitrate, 35 g / L ammonium citrate, 0.1 g / L 2-mercaptobenzimidazole, and 0.2 g / L EDTA (ethylenediaminetetraacetic acid). Process conditions for depositing copper plating: temperature 48℃, DC electroplating, current density 0.8A / dm³ 2 After 8 minutes, the thickness of the copper plating layer was 0.25 μm. In step S4, the current density drops to 2 A / dm.2 The time was 12 minutes, and the copper layer was thickened to 1 μm; the rest of the method was the same as in Example 1. Example 3:

[0038] This embodiment provides a method for preparing a multilayer functional copper current collector. The PET base film undergoes surface treatment, and the specific process is as follows: Step 1: Add lignin to anhydrous ethanol, disperse, then add tetraethyl orthosilicate, adjust the pH to 8 with 25 wt% ammonia, stir evenly to obtain composite lignin; the mass ratio of lignin, tetraethyl orthosilicate and anhydrous ethanol is 1:0.1:10. Step 2: Add the composite lignin to the dopamine hydrochloride solution, disperse, react at 40~60℃ for 4h, centrifuge, and dry to obtain the modified organic filler; the mass ratio of composite lignin to dopamine hydrochloride solution is 1:5; Step 3: Mix the modified organic filler with carboxylated carbon nanotubes, add anhydrous ethanol, disperse, then add polyacrylic acid, acetylacetonate diol, and sodium carboxymethyl cellulose, stir evenly to obtain the modified slurry; Step 4: Coat the upper and lower surfaces of the PET base film with the modified slurry, and dry to obtain the composite polymer base film; the coating amount of the modified slurry is 100g / m². 2 ; The modified slurry comprises the following components by weight: 10 parts modified organic filler, 1 part carboxylated carbon nanotubes, 5 parts polyacrylic acid, 0.5 parts acetylenic diol, and 1 part sodium carboxymethyl cellulose; the solid content of the modified slurry is 10%; the remaining methods are the same as in Example 1. Example 4:

[0039] This embodiment provides a method for preparing a multilayer functional copper current collector. The PET base film undergoes surface treatment, and the specific process is as follows: Step 1: Add lignin to anhydrous ethanol, disperse, then add tetraethyl orthosilicate, adjust the pH to 8.5 with 25 wt% ammonia, stir evenly to obtain composite lignin; the mass ratio of lignin, tetraethyl orthosilicate and anhydrous ethanol is 1:0.1:10. Step 2: Add the composite lignin to the dopamine hydrochloride solution, disperse, react at 40℃ for 4 hours, centrifuge, and dry to obtain the modified organic filler; the mass ratio of composite lignin to dopamine hydrochloride solution is 1:8. Step 3: Mix the modified organic filler with carboxylated carbon nanotubes, add anhydrous ethanol, disperse, then add polyacrylic acid, acetylacetonate diol, and sodium carboxymethyl cellulose, stir evenly to obtain the modified slurry; Step 4: Coat the upper and lower surfaces of the PET base film with the modified slurry, and dry to obtain the composite polymer base film; the coating amount of the modified slurry is 120 g / m².2 ; The modified slurry comprises the following components by weight: 15 parts modified organic filler, 3 parts carboxylated carbon nanotubes, 10 parts polyacrylic acid, 1 part acetylacetonate, and 2 parts sodium carboxymethyl cellulose; the solid content of the modified slurry is 20%; the remaining methods are the same as in Example 1. Example 5:

[0040] This embodiment provides a method for preparing a multilayer functional copper current collector. The PET base film undergoes surface treatment, and the specific process is as follows: Step 1: Add lignin to anhydrous ethanol and disperse it. Then add tetraethyl orthosilicate and adjust the pH to 10 with 25 wt% ammonia. Stir well to obtain composite lignin. The mass ratio of lignin, tetraethyl orthosilicate and anhydrous ethanol is 1:0.3:20. Step 2: Add the composite lignin to the dopamine hydrochloride solution, disperse, react at 60℃ for 6 hours, centrifuge, and dry to obtain the modified organic filler; the mass ratio of composite lignin to dopamine hydrochloride solution is 1:10. Step 3: Mix the modified organic filler with carboxylated carbon nanotubes, add anhydrous ethanol, disperse, then add polyacrylic acid, acetylacetonate diol, and sodium carboxymethyl cellulose, stir evenly to obtain the modified slurry; Step 4: Coat the upper and lower surfaces of the PET base film with the modified slurry, and dry to obtain the composite polymer base film; the coating amount of the modified slurry is 150 g / m². 2 ; The modified slurry comprises the following components by weight: 20 parts modified organic filler, 5 parts carboxylated carbon nanotubes, 15 parts polyacrylic acid, 2 parts acetylacetonate, and 3 parts sodium carboxymethyl cellulose; the solid content of the modified slurry is 30%; the remaining methods are the same as in Example 1.

[0041] Comparative Example 1: This comparative example provides a method for preparing a multilayer functional copper current collector. The pretreated functional current collector does not undergo pyrophosphate copper plating solution deposition of pyrophosphate copper, and the remaining methods are the same as in Example 1.

[0042] Comparative Example 2: This comparative example provides a method for preparing a multilayer functional copper current collector. The pretreated functional current collector does not undergo pyrophosphate copper plating solution deposition of pyrophosphate copper, and the remaining methods are the same as in Example 2.

[0043] Comparative Example 3: This comparative example provides a method for preparing a multilayer functional copper current collector. The polymer base film undergoes surface treatment, and the specific process is as follows: Step 1: Add lignin to anhydrous ethanol, disperse, then add tetraethyl orthosilicate, adjust the pH to 8, stir evenly, and obtain composite lignin; Step 2: Add the composite lignin to anhydrous ethanol and disperse it. Then add polyacrylic acid, acetylacetonate diol, and sodium carboxymethyl cellulose and stir evenly to obtain the modified slurry. Step 3: Coat the upper and lower surfaces of the polymer base film with the modified slurry and dry to obtain the composite polymer base film; the modified slurry includes the following components by mass: 15 parts of composite lignin, 5 parts of polyacrylic acid, 0.5 parts of acetylenic diol, and 1 part of sodium carboxymethyl cellulose; the solid content of the modified slurry is 10%; the rest of the method is the same as in Example 3.

[0044] Comparative Example 4: This comparative example provides a method for preparing a multilayer functional copper current collector. The polymer base film undergoes surface treatment, and the specific process is as follows: Step 1: Add lignin to anhydrous ethanol and disperse it. Then add polyacrylic acid, acetylacetonate diol, and sodium carboxymethyl cellulose and stir evenly to obtain the modified slurry. Step 2: Coat the upper and lower surfaces of the polymer base film with the modified slurry and dry to obtain the composite polymer base film; the modified slurry includes the following components by mass: 15 parts lignin, 5 parts polyacrylic acid, 0.5 parts acetylenic diol, and 1 part sodium carboxymethyl cellulose; the solid content of the modified slurry is 10%; the rest of the method is the same as in Example 3.

[0045] experiment: Samples were prepared from the functional current collectors obtained in Examples 1-5 and Comparative Examples 1-4, and their performance was tested and the test results were recorded.

[0046] Tensile strength and elongation at break: GB / T1040.3-2006 was used as the reference standard. An electronic universal testing machine was used. The test conditions were: gauge length 10 mm, tensile speed 100 mm / min, width 15 mm. Tensile strength and elongation at break were determined. Sheet resistance test: The four-probe method is used to measure the surface current and voltage of the current collector using a sheet resistance meter, and the sheet resistance value is calculated. Interlayer peel force test: Fix the sample at both ends of the tensile tester, start the tensile tester to peel the sample, and test its interlayer peel force; Areal density uniformity test: In a dark room, the composite current collector sample prepared above is placed close to a regular flat backlight with a brightness of 1200 Lux. The sample size is larger than the backlight panel, which is 30cm*30cm in size. A photo taken at a vertical angle shows that the light-transmitting area is a non-dense area and the opaque area is a dense area of ​​copper layer. The deviation between the areal density of a local area of ​​the sample and the average areal density of the entire material is tested to evaluate its areal density uniformity.

[0047] Performance Comparison Table

[0048] Based on the data in the table above, the following conclusions can be clearly drawn: The multilayer copper functional current collectors obtained in Examples 1-5 are compared with the functional current collectors obtained in Comparative Examples 1-4. The test results show that: Compared with Examples 1-2, the functional current collectors obtained in Comparative Examples 1-2 do not undergo pyrophosphate copper plating solution deposition of pyrophosphate copper, resulting in decreased tensile strength and elongation at break, increased sheet resistance, decreased peel force, and poor uniformity. This indicates that the present invention introduces a pyrophosphate copper transition layer between the magnetron sputtering seed layer and the thickened layer of acidic sulfate copper plating solution, which can significantly improve the performance of the functional copper current collector, demonstrating the technical advantages of the present invention in preparing multilayer functional copper current collectors.

[0049] Compared with Example 3, the functional copper current collector obtained in Comparative Example 3 does not have lignin complexed with dopamine, and no carboxylated carbon nanotubes are added to the modified slurry. The tensile strength and elongation at break are significantly reduced, the sheet resistance is increased, and the areal density uniformity is reduced. It can be seen that by adding carboxylated carbon nanotubes, the interfacial compatibility with the copper seed layer is increased, the thermal stress is reduced, and the surface carboxyl groups can improve the dispersibility of the modified organic filler in the slurry and increase the uniformity of the coating layer, which reflects the technical advantages of adding carboxylated carbon nanotubes in this invention.

[0050] Compared to Example 3, the functional current collector obtained in Comparative Example 4, without composite treatment of lignin, exhibited reduced tensile strength, elongation at break, increased sheet resistance, and decreased interlayer peeling force. This indicates that by combining lignin with silica, a composite lignin is formed. Amorphous silica has a high specific surface area, which significantly increases the corrosion and wear resistance of lignin, thereby improving the chemical corrosion resistance of the polymer base film layer in the electrolyte, reducing the contact resistance at the interface of the functional current collector, and thus enhancing the interfacial bonding strength and uniformity of the current collector.

[0051] 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 a multilayer functional copper current collector, characterized in that: Includes the following steps: S1: Copper is deposited by magnetron sputtering on the upper and lower surfaces of the polymer base film to form a copper seed layer, thus obtaining a pretreated functional current collector; S2: Immerse the pretreated functional current collector in a pyrophosphate copper plating solution, adjust the pH, deposit pyrophosphate copper to form a pyrophosphate copper layer, and dry to obtain a pyrophosphate copper functional current collector. S3: Immerse the pyrometallurgical copper current collector in an acidic sulfate copper plating solution to deposit copper, thicken the copper layer, and obtain a multilayer functional copper current collector.

2. The method for preparing a multilayer functional copper current collector according to claim 1, characterized in that: The preparation process of the copper seed layer is as follows: a polymer base film is loaded into a magnetron sputtering device, a vacuum is drawn, argon gas is introduced as the working gas, the pressure is 0.5~1.0Pa, a pure copper target is used, and copper is deposited on the upper and lower surfaces of the polymer base film by magnetron sputtering under the conditions of DC power of 5~8kW and polymer base film temperature of 60~80℃ to form a copper seed layer.

3. The method for preparing a multilayer functional copper current collector according to claim 1, characterized in that: The polymer base film is plasma cleaned before use, and then immersed in an alkaline solution for weak alkaline etching.

4. The method for preparing a multilayer functional copper current collector according to claim 1, characterized in that: The copper pyrophosphate plating solution comprises the following components by mass: 60-80 g / L copper pyrophosphate, 300-400 g / L potassium pyrophosphate, 20-30 g / L potassium nitrate, 30-40 g / L ammonium citrate, 0.1-0.3 g / L 2-mercaptobenzimidazole, and 0.2-0.5 g / L ethylenediaminetetraacetic acid.

5. The method for preparing a multilayer functional copper current collector according to claim 1, characterized in that: The acidic sulfate copper plating solution comprises the following components by mass: 250-260 g / L copper sulfate, 50-60 g / L sulfuric acid, 60-80 ppm chloride ions, and 0.5-0.8% additives.

6. The method for preparing a multilayer functional copper current collector according to claim 1, characterized in that: The thickness of the copper seed layer is 20~50nm; the thickness of the pyrocopper layer is 0.2~0.5μm; in step S3, the copper layer is thickened to 0.8~1.2μm; the thickness of the polymer base film layer is 3~8μm; the polymer base film is any one of polyethylene terephthalate and polypropylene.

7. The method for preparing a multilayer functional copper current collector according to claim 1, characterized in that: The polymer base film undergoes surface treatment, the specific process of which is as follows: Step 1: Add lignin to anhydrous ethanol, disperse, then add tetraethyl orthosilicate, adjust the pH, stir evenly, and obtain composite lignin; Step 2: Add the composite lignin to the dopamine hydrochloride solution, disperse, heat to react, centrifuge, and dry to obtain the modified organic filler; Step 3: Mix the modified organic filler with carboxylated carbon nanotubes, add anhydrous ethanol, disperse, then add polyacrylic acid, acetylacetonate diol, and sodium carboxymethyl cellulose, stir evenly to obtain the modified slurry; Step 4: Coat the upper and lower surfaces of the polymer base film with the modified slurry, and dry to obtain the composite polymer base film.

8. The method for preparing a multilayer functional copper current collector according to claim 7, characterized in that: The modified slurry comprises the following components by weight: 10-20 parts of modified organic filler, 1-5 parts of carboxylated carbon nanotubes, 5-15 parts of polyacrylic acid, 0.5-2 parts of acetylacetonate, and 1-3 parts of sodium carboxymethyl cellulose; the solid content of the modified slurry is 10-30%.

9. The method for preparing a multilayer functional copper current collector according to claim 7, characterized in that: In step four, the coating amount of the modified slurry is 100~150g / m². 2 .

10. A multilayer functional copper current collector, characterized in that: The multilayer functional copper current collector is prepared according to any one of claims 1-9.

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