Polypropylene-based composite copper foil and preparation method and application thereof
By treating the surface of polypropylene film using a gel grafting method, the problems of long grafting time and uneven copper plating in PP film were solved, and a stable polypropylene-based composite copper foil was prepared, which is suitable for lithium battery negative electrode current collectors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
- Filing Date
- 2024-02-06
- Publication Date
- 2026-06-12
AI Technical Summary
Existing PP film grafting technology requires long-term online processing, which makes industrial production difficult. In addition, traditional methods have problems such as uneven copper plating and complex processes.
The surface of a polypropylene membrane was treated using a gel grafting method. A gel was formed by mixing isobutanol, acrylic acid, and functional substances. After aging, the membrane was sensitized in SnCl2 and silver ammonia solution, and then electroless copper plating was performed to form a uniform copper layer.
Offline grafting of polypropylene film surface was achieved, shortening the processing time and producing polypropylene-based composite copper foil with uniform copper layer and strong bonding with the substrate, which is suitable for lithium battery negative electrode current collector.
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Figure CN117947411B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of copper foil preparation technology, and relates to a polypropylene-based composite copper foil and its preparation method, specifically to a method and application of gel grafting treatment of polypropylene film surface to prepare polypropylene-based composite copper foil. Background Technology
[0002] Composite copper foil with polymer film as the substrate has been widely studied as a negative electrode current collector for lithium batteries in recent years due to its advantages of lightweight and low cost, as well as its excellent performance in improving the puncture resistance of batteries. Compared with polyethylene terephthalate (PET), polypropylene (PP) has better thermal stability and is less prone to degradation in lithium batteries, exhibiting very stable performance. However, PP film itself also has certain disadvantages, such as poor surface hydrophilicity and few functional groups, making copper plating on its surface extremely difficult.
[0003] Traditional methods such as ultraviolet (UV) and solution grafting can be used to graft PP film surfaces, and while the results are significant, existing PP film grafting technologies require very long online processing times, ranging from several minutes to several hours, making these methods difficult to apply in industrial production. Furthermore, the UV method suffers from uneven illumination, leading to uneven grafting and subsequent copper plating. Solution grafting requires relatively high temperatures, causing some substances in the system to volatilize, necessitating the addition of a condensation reflux device, making the entire process very complex.
[0004] Therefore, one of the prerequisites for the industrial production of PP composite copper foil is to shorten the online processing time consumed by grafting on the PP film surface and simplify the process flow. This has been a long-term goal for researchers in the industry. Summary of the Invention
[0005] The main objective of this invention is to provide a method and application for gel grafting treatment of polypropylene film surface and preparation of polypropylene-based composite copper foil, so as to overcome the shortcomings of the prior art.
[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:
[0007] This invention provides a method for preparing polypropylene-based composite copper foil, comprising:
[0008] The mixture containing isobutanol, acrylic acid, selected functional substances and water is thoroughly stirred and mixed to form a gel. The selected functional substances include any one or a combination of two or more of cellulose, guar gum and gum arabic.
[0009] The gel was applied to the surface of a polypropylene film and aged to obtain a surface-carboxylated polypropylene film.
[0010] The surface-carboxylated polypropylene film is sequentially immersed in SnCl2 aqueous solution and silver ammonia solution, and then immersed in copper plating solution for chemical copper plating treatment, thereby depositing a copper layer on the surface of the polypropylene film to obtain polypropylene-based composite copper foil.
[0011] In some embodiments, the copper immersion solution comprises a mixture of copper sulfate, EDTA-2Na, and formaldehyde.
[0012] This invention also provides a polypropylene-based composite copper foil, which is prepared by the aforementioned method.
[0013] Furthermore, the polypropylene-based composite copper foil includes a polypropylene film as a substrate and a copper layer tightly bonded to the surface of the polypropylene film.
[0014] This invention also provides the application of the aforementioned polypropylene-based composite copper foil in the preparation of lithium battery negative electrode current collectors.
[0015] Compared with the prior art, the beneficial effects of the present invention include:
[0016] The method for gel grafting treatment of polypropylene film surface and preparation of polypropylene-based composite copper foil provided by this invention enables offline grafting of polypropylene film surface, greatly shortening the online processing time of the product and transforming the online process into an offline process. This makes it industrially possible to treat the surface of polypropylene film through chemical grafting. Furthermore, the prepared polypropylene-based composite copper foil is very stable, with a uniform copper layer and strong adhesion to the substrate, exhibiting excellent bonding strength. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram illustrating the principle of a method for gel grafting polypropylene membrane surface treatment and preparing polypropylene-based composite copper foil in a typical embodiment of the present invention.
[0019] Figure 2 This is the infrared spectrum of the polypropylene film surface after gel grafting in Example 3 of the present invention;
[0020] Figure 3This is a photograph of the polypropylene film before grafting in Embodiment 3 of the present invention;
[0021] Figure 4 This is a photograph of the gel-grafted polypropylene film in Example 3 of the present invention.
[0022] Figure 5 This is a physical image of the polypropylene-based composite copper foil obtained by chemical copper plating after gel grafting in Example 3 of the present invention. Detailed Implementation
[0023] Given the shortcomings of existing PP (polypropylene) film grafting technologies, which all require very long online processing times, the inventors of this invention, after extensive research and numerous experiments, have proposed this technical solution. This solution primarily provides a novel PP film grafting technique for the preparation of composite copper foil, employing a novel chemical grafting method for the surface of polypropylene films. This method has not been reported in any previous literature. Because the PP films used are very thin, the area of PP film that the production line needs to process per unit time is very large, depending on production capacity requirements. If the online processing time is too long, it is impossible to construct such a long growth line. The gel grafting technology provided by this invention transforms the online grafting process of PP films into an offline process. It only requires coating the PP film surface with a specially formulated gel, after which it can be rolled up and stored at a rated temperature for a period of time. After this process, the PP film surface exhibits carboxylation. Subsequent chemical copper plating can achieve twice the result with half the effort. The resulting PP-based composite copper foil has the advantages of uniform copper plating and strong adhesion between the copper layer and the substrate.
[0024] The following will provide a further explanation of the technical solution, its implementation process, and its principles.
[0025] As one aspect of the technical solution of this invention, a method for preparing a polypropylene-based composite copper foil includes:
[0026] The mixture containing isobutanol, acrylic acid, selected functional substances and water is thoroughly stirred and mixed to form a gel;
[0027] The gel was applied to the surface of a polypropylene film and aged to obtain a surface-carboxylated polypropylene film.
[0028] The surface-carboxylated polypropylene film is sequentially immersed in SnCl2 aqueous solution and silver ammonia solution, and then immersed in copper plating solution for chemical copper plating treatment, thereby depositing a copper layer on the surface of the polypropylene film to obtain polypropylene-based composite copper foil.
[0029] In some embodiments, the selected functional substance includes any one or a combination of two or more of cellulose, guar gum, and gum arabic. The role of cellulose, guar gum, and gum arabic is to form a gel matrix, transforming the solution system into a gel system.
[0030] In some embodiments, the isobutanol content in the mixed slurry is 0–90 g / L.
[0031] In some embodiments, the acrylic acid content in the mixed slurry is 2 to 300 g / L.
[0032] In some embodiments, the total content of the selected functional substances in the mixed slurry is 1 to 200 g / L.
[0033] In some embodiments, the temperature of the mixed slurry during stirring is 0–90°C, and the stirring time is 10 min–72 h.
[0034] In some embodiments, the preparation method includes coating the gel onto the surface of a polypropylene film with a coating thickness of 5 μm to 10 mm.
[0035] In some embodiments, the preparation method includes: winding up a polypropylene film and placing it in a constant temperature environment for the aging treatment, wherein the temperature is 0 to 150°C and the time is 20 min to 96 h.
[0036] In some embodiments, the concentration of the SnCl2 aqueous solution is 1–20 g / L.
[0037] Furthermore, the polypropylene film is immersed in SnCl2 aqueous solution for 10 seconds to 30 minutes. The purpose of immersing the surface-carboxylated polypropylene film in SnCl2 is to sensitize it, facilitating the subsequent deposition of silver ions on the modified polypropylene film.
[0038] In some embodiments, the concentration of the silver ammonia solution is 0.1–5 wt%.
[0039] Furthermore, the polypropylene film is immersed in the silver ammonia solution for 2 to 30 minutes, which allows the surface of the treated polypropylene film to adsorb a layer of silver ions, giving the substrate surface catalytic activity and enabling the rapid and uniform formation of a copper layer on the substrate surface.
[0040] In some embodiments, the copper immersion solution comprises a mixture of copper salt, EDTA-2Na, and formaldehyde.
[0041] Specifically, the concentration of copper salt in the copper precipitation solution is 0.01 mol / L to 2 mol / L, the concentration of EDTA-2Na is 0.02 mol / L to 1 mol / L, and the formaldehyde content is 5 mL / L to 30 mL / L.
[0042] Furthermore, the copper salt may be copper sulfate, but is not limited thereto.
[0043] In some embodiments, the temperature of the copper plating solution is 20°C to 80°C during the chemical copper plating process.
[0044] Furthermore, the time for the chemical copper plating treatment is 30 seconds to 1 hour.
[0045] Please see Figure 1 As shown, the preparation mechanism of this invention is as follows: a novel gel grafting method is used to graft polypropylene (PP) film surface. Utilizing the property of gels to fix liquid molecules and prevent volatile substances, the grafting solution remains on the PP film surface for a long time. First, a mixture containing water, isobutanol, acrylic acid, cellulose, guar gum, and gum arabic is stirred to form a gel, which is then uniformly coated on the PP film surface. The film is then wound up and aged under a set stable condition for a period of time to carboxylate the PP film surface. Afterward, the treated PP film is washed clean and successively immersed in SnCl2 aqueous solution and silver ammonia solution. Finally, it undergoes chemical copper plating in a mixed solution of EDTA-2Na, copper sulfate, and formaldehyde to obtain PP-based composite copper foil.
[0046] In one of the more preferred embodiments, a method for gel grafting polypropylene film surface treatment and preparing composite copper foil includes the following steps:
[0047] Step 1: Add isobutanol, acrylic acid, cellulose, guar gum, and gum arabic to water and stir until homogeneous. In this aqueous slurry, the isobutanol content is between 0 and 90 g / L, and the acrylic acid content is between 2 and 300 g / L. Cellulose, guar gum, and gum arabic can be added in their entirety, or one or two can be added, with the total amount added in the slurry between 1 and 200 g / L; the slurry temperature during stirring is between 0 and 90°C, and the stirring time is between 10 minutes and 72 hours.
[0048] Step 2: The well-stirred slurry will eventually become a gel. Coat the surface of the polypropylene film with a thickness between 5 μm and 10 mm. Roll up the polypropylene film and place it in a constant temperature environment between 0 and 150°C for 20 min to 96 h.
[0049] Step 3: Remove the polypropylene film after placement and wash off the gel on the surface; then soak it in an aqueous SnCl2 solution with a SnCl2 concentration between 1 and 20 g / L and a soaking time between 10 seconds and 30 minutes.
[0050] Step 4: Remove the polypropylene film and immerse it again in a silver ammonia solution. The concentration of Ag(NH3)2OH in the silver ammonia solution is between 0.1 wt% and 5 wt%, and the immersion time is between 2 min and 30 min.
[0051] Step 5: Remove the treated polypropylene film and immerse it in a chemical copper plating solution. The copper plating solution consists of: copper sulfate concentration between 0.01 mol / L and 2 mol / L, EDTA-2Na concentration between 0.02 mol / L and 1 mol / L, and formaldehyde concentration between 5 mL / L and 30 mL / L. The temperature of the copper plating solution is between 20℃ and 80℃, and the copper plating time is between 30 seconds and 1 hour. Afterward, the polypropylene-based composite copper foil material is obtained.
[0052] In summary, this invention employs a novel gel coating method that overcomes the disadvantage of long online processing times in traditional polypropylene membrane surface grafting. By using an offline processing method for membrane surface grafting, the online processing time is significantly shortened, transforming an online process into an offline one. This makes chemical grafting a viable method for functionalizing polypropylene membrane surfaces in industrial production. Based on this, a polypropylene-based composite copper foil with a uniform copper layer and strong adhesion to the substrate is prepared through chemical plating. The hydrophilicity of the polypropylene membrane surface after gel grafting treatment is significantly enhanced, and the number of functional groups is significantly increased, providing a good foundation for subsequent chemical copper plating.
[0053] As another aspect of the technical solution of the present invention, it also relates to a polypropylene-based composite copper foil, which is prepared by the aforementioned preparation method.
[0054] Furthermore, the polypropylene-based composite copper foil includes a polypropylene film as a substrate and a copper layer tightly bonded to the surface of the polypropylene film.
[0055] Furthermore, the thickness of the copper layer is 0.1 μm to 10 μm.
[0056] Furthermore, the peel strength of the polypropylene-based composite copper foil is 2 MPa to 10 MPa.
[0057] The polypropylene-based composite copper foil prepared by this invention is very stable, and the copper layer has good adhesion to the substrate.
[0058] This invention also provides applications of the aforementioned polypropylene-based composite copper foil. For example, the polypropylene-based composite copper foil can be used as a current collector for lithium battery anodes, and has good application prospects in the preparation of lithium battery anodes.
[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; all modifications conceived of or derived from the content disclosed herein are considered to be within the scope of protection of this invention.
[0060] Example 1
[0061] Acrylic acid, cellulose, guar gum, and gum arabic were mixed with water until homogeneous. The acrylic acid content in this aqueous slurry was 2 g / L. Cellulose, guar gum, and gum arabic were all added, with a total added content of 200 g / L in the slurry. The slurry temperature was 90℃, and the mixing time was 72 h. The homogeneous slurry eventually formed a gel, which was then coated onto the surface of a polypropylene film to a thickness of 5 μm. The polypropylene film was rolled up and placed in a constant temperature environment at 150℃ for 20 min. After the placement, the polypropylene film was removed, and the gel on the surface was washed off. Then, it was immersed in a SnCl2 aqueous solution with a SnCl2 concentration of 20 g / L for 10 s. The polypropylene film was then removed and immersed again in a silver ammonia solution with a silver ammonia concentration of 0.1 wt% for 10 min. Finally, the treated polypropylene film was removed and immersed in a chemical copper plating solution. The copper immersion solution consisted of: 0.01 mol / L copper sulfate, 0.02 mol / L EDTA-2Na, and 5 mL / L formaldehyde. The solution was heated to 20°C and the immersion time was 1 hour, after which polypropylene-based composite copper foil material was obtained.
[0062] Example 2
[0063] Isobutanol, acrylic acid, and cellulose were mixed with water until homogeneous. The isobutanol content in this aqueous slurry was 90 g / L, and the acrylic acid content was 300 g / L. The total amount of cellulose added to the slurry was 1 g / L. The slurry temperature was 0°C, and the mixing time was 10 min. The homogeneous slurry eventually became a gel, which was then coated onto the surface of a polypropylene film to a thickness of 10 mm. The polypropylene film was rolled up and placed in a constant temperature environment at 0°C for 96 h. After the storage period, the polypropylene film was removed, and the gel on the surface was washed off. Then, it was immersed in a SnCl2 aqueous solution with a SnCl2 concentration of 1 g / L for 30 min. The polypropylene film was then removed and immersed again in a silver ammonia solution with an Ag(NH3)2OH concentration of 5 wt% for 30 min. Finally, the treated polypropylene film was removed and immersed in a chemical copper plating solution. The copper immersion solution consisted of 2 mol / L copper sulfate, 1 mol / L EDTA-2Na, and 30 mL / L formaldehyde. The solution temperature was 80℃, and the immersion time was 30 seconds, after which polypropylene-based composite copper foil material was obtained.
[0064] Example 3
[0065] Isobutanol, acrylic acid, and cellulose were mixed with water until homogeneous. In this aqueous slurry, the content of isobutanol was 20 g / L, and the content of acrylic acid was 90 g / L. The total amount of cellulose added to the slurry was 12 g / L. The slurry temperature during mixing was 25℃, and the mixing time was 40 min. The homogeneous slurry eventually became a gel. This gel was coated onto the surface of a polypropylene film to a thickness of 2 mm. The infrared spectrum of the polypropylene film surface after gel grafting is shown below. Figure 2 As shown in the picture, the actual product is as follows. Figure 4 As shown, a milky white grafted layer appears on the surface. A photograph of the polypropylene film before grafting is shown below. Figure 3 As shown, the polypropylene film is transparent. The film was rolled up and placed in a constant temperature environment (80℃) for 12 hours. After placement, the polypropylene film was removed and the surface gel was washed off. It was then immersed in a SnCl2 aqueous solution (7 g / L) for 10 minutes. The film was then removed and immersed again in a silver ammonia solution (3 wt% Ag(NH3)2OH) for 2 minutes. The treated polypropylene film was then immersed in a chemical copper plating solution. The copper plating solution consisted of 0.5 mol / L copper sulfate, 0.3 mol / L EDTA-2Na, and 15 mL / L formaldehyde. The solution temperature was 50℃, and the plating time was 2 minutes. This yielded a polypropylene-based composite copper foil material.
[0066] The actual image of the polypropylene-based composite copper foil obtained by electroless copper plating after gel grafting in this embodiment is shown in the figure below. Figure 5 As shown, its thickness is 1 μm and its peel strength is 5 MPa.
[0067] Example 4
[0068] Isobutanol, acrylic acid, cellulose, and guar gum were mixed with water until homogeneous. The isobutanol content in this aqueous slurry was 50 g / L, and the acrylic acid content was 200 g / L. The total amount of cellulose and guar gum in the slurry was 10 g / L. The slurry temperature was 20°C, and the mixing time was 30 min. The homogeneous slurry eventually formed a gel, which was then coated onto the surface of a polypropylene film to a thickness of 5 mm. The polypropylene film was rolled up and placed in a constant temperature environment at 80°C for 48 h. After the storage period, the polypropylene film was removed, and the gel on the surface was washed off. Then, it was immersed in a SnCl2 aqueous solution with a SnCl2 concentration of 10 g / L for 20 min. The polypropylene film was then removed and immersed again in a silver ammonia solution with an Ag(NH3)2OH concentration of 3 wt% for 10 min. Finally, the treated polypropylene film was removed and immersed in a chemical copper plating solution. The copper immersion solution consisted of 1 mol / L copper sulfate, 0.1 mol / L EDTA-2Na, and 15 mL / L formaldehyde. The solution temperature was 50℃, and the immersion time was 30 min. This yielded a polypropylene-based composite copper foil material with a thickness of 0.1 μm and a peel strength of 2 MPa.
[0069] Example 5
[0070] Isobutanol, acrylic acid, guar gum, and gum arabic were mixed with water until homogeneous. The isobutanol content in this aqueous slurry was 30 g / L, and the acrylic acid content was 50 g / L. The total amount of guar gum and gum arabic in the slurry was 100 g / L. The slurry temperature was 30°C, and the mixing time was 24 h. The homogeneous slurry eventually became a gel, which was then coated onto the surface of a polypropylene film to a thickness of 2 mm. The polypropylene film was rolled up and placed in a constant temperature environment (25°C) for 68 h. After the storage period, the polypropylene film was removed, and the gel on the surface was washed off. Then, it was immersed in a SnCl2 aqueous solution (5 g / L) for 25 min. The polypropylene film was then removed and immersed again in a silver ammonia solution (0.5 wt% Ag(NH3)2OH) for 20 min. Finally, the treated polypropylene film was immersed in a chemical copper plating solution. The copper plating solution consisted of: 0.1 mol / L copper sulfate, 0.5 mol / L EDTA-2Na, and 10 mL / L formaldehyde. The solution temperature was 60℃, and the plating time was 40 min. This yielded a polypropylene-based composite copper foil material with a thickness of 3 μm and a peel strength of 6 MPa.
[0071] Compare with Example 1
[0072] The difference between this comparative example and Example 1 is that no cellulose, guar gum, or gum arabic was added to the aqueous slurry.
[0073] Without the addition of the aforementioned cellulose, guar gum, gum arabic, and other components, this control example cannot retain water, causing the water in the system to evaporate rapidly at high temperatures, rendering the grafting scheme ineffective.
[0074] Compare with Example 2
[0075] The difference between this comparative example and Example 1 is that the step of soaking in an aqueous SnCl2 solution is omitted.
[0076] This comparative example lacks a sensitization process, which prevents the polymer surface from effectively adsorbing silver ions and thus prevents the deposition of a copper layer.
[0077] Compare with Example 3
[0078] The difference between this comparative example and Example 1 is that the step of soaking in silver ammonia solution is omitted.
[0079] This comparative example lacks an activation process, which prevents the polymer surface from effectively adsorbing silver ions and thus hinders the deposition of a copper layer. Therefore, both sensitization and activation steps are indispensable for the deposition of a copper layer.
[0080] In addition, the inventors of this case also conducted experiments with other raw materials and conditions listed in this specification, referring to Examples 1-5, and similarly obtained polypropylene-based composite copper foil with uniform copper layer and strong adhesion to the substrate.
[0081] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.
[0082] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.
Claims
1. A method for preparing a polypropylene-based composite copper foil, characterized in that, include: A slurry containing isobutanol, acrylic acid, selected functional substances and water is thoroughly stirred and mixed to form a gel. The selected functional substances include any one or more combinations of cellulose, guar gum and gum arabic. The content of isobutanol in the slurry is 20-90 g / L, the content of acrylic acid is 2-300 g / L, and the total content of the selected functional substances is 1-200 g / L. The gel is coated on the surface of a polypropylene film with a coating thickness of 5 μm to 10 mm. The coated polypropylene film is then rolled up and placed in a constant temperature environment for aging treatment. The temperature is 0 to 150 °C and the time is 20 min to 96 h to obtain a surface carboxylated polypropylene film. The surface-carboxylated polypropylene film is sequentially immersed in SnCl2 aqueous solution and silver ammonia solution, and then immersed in copper plating solution for chemical copper plating treatment, thereby depositing a copper layer on the surface of the polypropylene film to obtain polypropylene-based composite copper foil.
2. The preparation method according to claim 1, characterized in that: The temperature of the mixed slurry during stirring is 0–90°C, and the stirring time is 10 min–72 h.
3. The preparation method according to claim 1, characterized in that: The concentration of the SnCl2 aqueous solution is 1–20 g / L.
4. The preparation method according to claim 1, characterized in that: The polypropylene film was immersed in SnCl2 aqueous solution for 10 s to 30 min.
5. The preparation method according to claim 1, characterized in that: The concentration of the silver ammonia solution is 0.1–5 wt%.
6. The preparation method according to claim 1, characterized in that: The polypropylene film was immersed in silver ammonia solution for 2–30 min.
7. The preparation method according to claim 1, characterized in that: The copper immersion solution comprises a mixture of copper salt, EDTA-2Na, and formaldehyde. The concentration of copper salt in the copper immersion solution is 0.01 mol / L to 2 mol / L, the concentration of EDTA-2Na is 0.02 mol / L to 1 mol / L, and the content of formaldehyde is 5 mL / L to 30 mL / L.
8. The preparation method according to claim 7, characterized in that: The copper salt includes copper sulfate.
9. The preparation method according to claim 1, characterized in that: When performing chemical copper plating, the temperature of the copper plating solution is 20℃~80℃; and / or, the time of the chemical copper plating is 30 s~1 h.
10. A polypropylene-based composite copper foil, characterized in that, The polypropylene-based composite copper foil is prepared by the preparation method according to any one of claims 1-9, and the polypropylene-based composite copper foil includes a polypropylene film as a substrate and a copper layer tightly bonded to the surface of the polypropylene film.
11. The polypropylene-based composite copper foil according to claim 10, characterized in that: The thickness of the copper layer is 0.1µm to 10µm.
12. The polypropylene-based composite copper foil according to claim 10, characterized in that: The peel strength of the polypropylene-based composite copper foil is 2 MPa to 10 MPa.
13. The application of the polypropylene-based composite copper foil according to any one of claims 10-12 in the preparation of a negative electrode current collector for lithium batteries.