Composite current collector, preparation method therefor and use thereof

Abstract

The present invention relates to a composite current collector, a preparation method therefor and a use thereof. The composite current collector comprises a polymer-based film layer and a metal layer provided on at least one surface of the polymer-based film layer; the polymer-based film layer comprises a metal embedded layer in contact with the metal layer; a strength factor A of the composite current collector is formula (1); and formula (2). In the present invention, a strength factor of the composite current collector is controlled within a certain range, so that the tensile strength of the composite current collector can be significantly improved relative to the tensile strength of the base film. In addition, the composite current collector of the present invention also has good peel strength and low sheet resistance.

Description

A composite current collector, its preparation method and application Technical Field

[0001] This invention relates to the field of electronic components, and more specifically, to a composite current collector, its preparation method, and its application. Background Technology

[0002] Composite current collectors are high-performance conductive materials, typically composed of two metal layers (e.g., copper) and a polymer substrate layer (e.g., PET, PP, PI, etc.). As an alternative to electrolytic copper foil used in lithium batteries, composite current collectors offer advantages such as low cost, thinness, high safety performance, and high energy density, and are widely used in flexible electronic devices, film capacitors, electromagnetic shielding, and other fields.

[0003] Despite the excellent performance of composite current collectors in many aspects, their peel strength between the metal layer and the base film, as well as their tensile strength, still need further improvement. Since composite current collectors are composite structures, good peel strength is a fundamental requirement. During battery manufacturing and daily use, composite current collectors must withstand various forces, including internal electrolyte pressure and external mechanical impacts; therefore, improving their tensile strength is essential.

[0004] The tensile strength of composite current collectors is affected by the tensile strength of the base film itself and the composite process. Existing composite processes are prone to damaging the base film, resulting in no significant improvement in the tensile strength of the composite current collector compared to the base film, and sometimes even lower strength. If the tensile strength of the composite current collector is lower than that of the base film, it will negatively impact product yield and may also affect the durability and safety of high-performance batteries.

[0005] Patent CN117497687A discloses a method for preparing a composite copper foil current collector. The copper layer sputtered by magnetron sputtering has poor adhesion to the polymer base film. Furthermore, the high temperature during magnetron sputtering can cause perforation and damage to the polymer base film, resulting in no significant improvement in the tensile strength of the composite copper foil current collector relative to the base film. Summary of the Invention

[0006] The primary objective of this invention is to overcome the problems of existing composite current collectors having no significant improvement in tensile strength relative to the base film and further improved peel strength, and to provide a composite current collector.

[0007] A further objective of this invention is to provide a method for preparing a composite current collector.

[0008] A further objective of this invention is to provide the application of the aforementioned composite current collector in the preparation of lithium-ion battery anodes.

[0009] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0010] A composite current collector includes a polymer base film layer and a metal layer disposed on at least one surface of the polymer base film layer, wherein the polymer base film layer includes a metal embedded layer in contact with the metal layer;

[0011] The intensity factor of the composite current collector for The

[0012] Where D is the thickness of the metal layer, D0 is the thickness of the polymer base film layer, and d is the thickness of the metal embedding layer.

[0013] In this invention, the thickness D of the metal layer, the thickness D0 of the polymer base film layer, and the thickness d of the metal-embedded layer are all measured in the same units. The metal-embedded layer refers to a layer where polymer and metal coexist, formed when metal is embedded into the pores of the polymer base film. The thickness d of the metal-embedded layer refers to the shortest distance from the deepest copper embedded in the polymer base film to the surface of the polymer base film layer.

[0014] The inventors of this invention have discovered that by controlling the strength factor of the composite current collector within a certain range, the tensile strength of the composite current collector relative to the tensile strength of the polymer base film can be significantly improved. Specifically, within this range, the tensile strength of the composite current collector... R0 represents the tensile strength of the polymer-based film. Furthermore, by adjusting the strength factor, the composite current collector can also exhibit good peel strength.

[0015] If the strength factor is too small or a metal embedding layer is not provided, the tensile strength of the composite current collector will not be significantly improved relative to the tensile strength of the base film, and the peel strength of the composite current collector will also be poor. The strength factor should also not be too large, because the thinness and lightness of the composite current collector is one of the main reasons for its replacement of traditional metal foils (such as electrolytic copper foil). If the strength factor is too large, the thickness D of the metal layer will be too large, thus negating the thinness and lightness advantage of the composite current collector, and increasing manufacturing costs, making it unsuitable as a replacement for traditional metal foils.

[0016] In this invention, the intensity factor of the composite current collector Specifically, the values ​​can be 0.3, 0.33, 0.37, 0.40, 0.47, 0.50, 0.56, 0.6, 0.7, 0.78, 0.80, 0.86, 0.90, 1.00, 1.07, 1.10, 1.15, 1.17, or 1.2.

[0017] Preferably, the intensity factor of the composite current collector... for

[0018] More preferably, the intensity factor of the composite current collector... for

[0019] More preferably, the intensity factor of the composite current collector... for

[0020] Optionally, the thickness of the metal layer is: 0.5μm≤D≤1.5μm.

[0021] Preferably, the thickness of the metal layer is: 1μm≤D≤1.5μm.

[0022] Optionally, the thickness of the polymer-based film layer is: 2μm≤D0≤8μm.

[0023] Preferably, the thickness of the polymer base film layer is: 3μm≤D0≤5μm.

[0024] More preferably, the thickness of the polymer base film layer is: 3μm≤D0≤3.5μm.

[0025] Optionally, the thickness of the metal embedding layer is: 0.1 μm ≤ d ≤ D0 / 2 μm. Wherein, "D0 / 2" refers to the value obtained by dividing the thickness D0 of the polymer base film by 2.

[0026] Preferably, the thickness of the metal embedding layer is: 0.1μm≤d≤1.5μm.

[0027] More preferably, the thickness of the metal embedding layer is: 0.5μm≤d≤1.5μm.

[0028] Optionally, the polymer material of the polymer base film layer is at least one of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, or polypropylene.

[0029] Optionally, the material of the metal layer is at least one of copper, copper alloy, nickel, nickel alloy, silver, or silver alloy.

[0030] Optionally, the metal in the metal embedding layer is at least one of copper, copper alloy, nickel, nickel alloy, silver, or silver alloy.

[0031] Optionally, the number of metal layers is two, which are respectively disposed on the two surfaces of the polymer base film layer.

[0032] Preferably, the porosity of the polymer base film in the polymer base film layer is 5-70%.

[0033] More preferably, the porosity of the polymer base film in the polymer base film layer is 20-50%.

[0034] More preferably, the porosity of the polymer-based membrane is 30-50%.

[0035] Optionally, the average pore size of the polymer base film in the polymer base film layer is 20–100 nm.

[0036] Optionally, the tensile strength of the polymer base film in the polymer base film layer is 200-380 MPa.

[0037] Preferably, the tensile strength of the polymer base film of the polymer base film layer is 210-360 MPa.

[0038] More preferably, the polymer base film of the polymer base film layer has a tensile strength of 320-360 MPa.

[0039] A method for preparing a composite current collector includes the following steps:

[0040] S1. The polymer base film is subjected to plasma treatment, sensitization treatment and activation treatment to obtain a pretreated polymer base film;

[0041] S2. Perform chemical plating on the pretreated polymer base film to form a metal intercalation layer in the polymer base film, thereby obtaining a metallized base film;

[0042] S3. Electroplating is performed on the metallized base film to form a metal layer, thus obtaining the composite current collector.

[0043] The chemical plating and electroplating method of this invention, which combines a polymer base film and a metal layer, not only forms a metal intercalation layer within the polymer base film, but also does not damage the polymer base film. This results in a significant increase in the tensile strength of the composite current collector relative to the tensile strength of the base film, while also improving the peel strength of the composite current collector. Furthermore, the preparation method of this invention is applicable not only to commonly used polymer base films made of PP and PET, but also to polymer base films made of PE.

[0044] Optionally, the porosity of the polymer-based membrane in step S1 is 5% to 70%; specifically, it can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, or 70%.

[0045] Preferably, the porosity of the polymer-based membrane in step S1 is 20-50%.

[0046] More preferably, the porosity of the polymer-based membrane in step S1 is 30-50%.

[0047] Optionally, the average pore size of the polymer-based film in step S1 is 20–100 nm.

[0048] Optionally, the plasma treatment in step S1 has a power of 50-200W and a time of 60-300s.

[0049] Optionally, the sensitizing solution used in step S1 includes the following components at the following concentrations: SnCl2 5-25 g / L and HCl 10-35 ml / L.

[0050] Optionally, the sensitization treatment in step S1 takes 0.5 to 3 minutes.

[0051] Optionally, after the sensitization treatment in step S1 and before the activation treatment, a cleaning step is also included.

[0052] Optionally, the cleaning agent used for cleaning is water.

[0053] Optionally, the cleaning time is 5 to 15 seconds.

[0054] Optionally, the activation solution used in step S1 includes the following concentrations: PdCl2 0.5-2 g / L and HCl 8-20 ml / L.

[0055] Optionally, the activation treatment time in step S1 is 0.5 to 3 minutes.

[0056] Optionally, the activation process in step S1 further includes a drying step.

[0057] Optionally, the chemical plating in step S2 can be performed once or twice.

[0058] Optionally, when the electroless plating is performed once, the electroless plating solution includes the following components at the following concentrations: copper sulfate 5-10 g / L, disodium EDTA 30-60 g / L, bipyridine 5-20 mg / L, sodium hydroxide 3-8 g / L, and formaldehyde 5-10 g / L; the electroless plating time is 6-8 min.

[0059] Preferably, when the electroless plating is performed twice, the electroless plating sequentially includes a first electroless plating and a second electroless plating; the electroless plating solution for the first electroless plating includes the following components at the following concentrations: copper sulfate 5-10 g / L, disodium EDTA 30-60 g / L, bipyridine 5-20 mg / L, sodium hydroxide 3-8 g / L, and formaldehyde 5-10 g / L; the electroless plating solution for the second electroless plating includes the following components at the following concentrations: copper sulfate 5-15 g / L, disodium EDTA 5-10 g / L, potassium sodium tartrate 20-40 g / L, bipyridine 5-20 mg / L, sodium hydroxide 5-10 g / L, and formaldehyde 5-20 g / L.

[0060] Compared to single-pass electroless plating, double-pass electroless plating, through the combination of the first and second electroless plating processes, can achieve the same thickness of the metal inlay layer in a shorter time, resulting in higher efficiency.

[0061] Optionally, the first electroless plating time is 1 to 3 minutes; the second electroless plating time is 1 to 2 minutes.

[0062] Optionally, the electroplating in step S2 is a multi-segment electroplating.

[0063] Optionally, step S2 may further include a corrosion inhibition treatment step after electroplating.

[0064] Optionally, the corrosion inhibition treatment is performed by immersion in a corrosion inhibitor solution.

[0065] Optionally, the immersion time in the corrosion inhibitor is 2 to 5 minutes, and the temperature is 30 to 70°C.

[0066] Optionally, the corrosion inhibitor used for immersion includes components with the following concentrations: BTA 5-20 mg / L and ammonium molybdate 2-30 mg / L.

[0067] The application of the aforementioned composite current collector in the preparation of lithium-ion battery anodes is also within the scope of protection of this invention.

[0068] Compared with the prior art, the beneficial effects of the present invention are:

[0069] (1) This invention regulates the strength factor of the composite current collector within a certain range, which significantly improves the tensile strength of the composite current collector relative to the tensile strength of the base film; at the same time, regulating the strength factor also gives the composite current collector good peel strength. In addition, the composite current collector of this invention also has low sheet resistance.

[0070] (2) By using the chemical plating + electroplating method of the present invention to composite the polymer base film and the metal layer, a metal embedding layer can be formed in the polymer base film without damaging the polymer base film. This significantly improves the tensile strength of the composite current collector relative to the tensile strength of the base film, and also enhances the peel strength of the composite current collector. Furthermore, the preparation method of the present invention is applicable not only to commonly used polymer base films made of PP and PET, but also to polymer base films made of PE. Attached Figure Description

[0071] Figure 1 is a schematic diagram of the composite current collector in Example 2.

[0072] Figure 2 is a SEM image of the surface of the composite current collector in Example 2.

[0073] Figure 3 is a SEM image of the cross-section of the composite current collector in Example 2. Detailed Implementation

[0074] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0075] Example 1

[0076] This embodiment provides a composite current collector, which includes a polymer base film layer 1 and a metal layer 2 disposed on both surfaces of the polymer base film layer 1. The polymer base film layer 1 includes a metal embedding layer 11 in contact with the metal layer. The thickness D0 of the polymer base film layer 1 is 3 μm, the thickness D of the metal layer 2 is 1 μm, and the thickness d of the metal embedding layer 11 is 1.5 μm. The polymer material of the polymer base film layer 1 is polyethylene, the material of the metal layer 2 is copper, and the polymer material of the metal embedding layer 11 is polyethylene, and the metal in the metal embedding layer 11 is copper. The porosity of the polymer base film of the polymer base film layer 1 is 30%.

[0077] The preparation method of the composite current collector in this embodiment includes the following steps:

[0078] 1) A PE membrane with a porosity of 30%, an average pore diameter of 80 nm, and a thickness of 3 μm was selected as the polymer base membrane. The base membrane was first subjected to low-pressure plasma treatment, then immersed in a prepared sensitization solution for 2 min, followed by washing in deionized water for 10 s. After washing, it was immersed in an activation solution for 2 min, and then dried at 60℃ for 2 min to obtain the pretreated polymer base membrane. The plasma treatment conditions were: power 50 W, time 80 s, and argon as the plasma treatment gas; the sensitization solution consisted of SnCl2 20 g / L, HCl 30 ml / L, and deionized water as the solvent; the activation solution consisted of PdCl2 1.0 g / L, HCl 10 ml / L, and deionized water as the solvent.

[0079] 2) Immerse the pretreated polymer base film in the first chemical plating solution for 3 minutes, stirring continuously during the immersion process. Then immerse it in the second chemical plating solution for 1 minute, stirring continuously during the immersion process. Remove the film to obtain the metallized film. The composition of the first chemical plating solution is: copper sulfate 6 g / L, disodium EDTA 50 g / L, bipyridine 15 mg / L, sodium hydroxide 6 g / L, formaldehyde 5 g / L, and deionized water as the solvent. The composition of the second chemical plating solution is: copper sulfate 8 g / L, disodium EDTA 5 g / L, potassium sodium tartrate 40 g / L, bipyridine 10 mg / L, sodium hydroxide 8 g / L, formaldehyde 15 g / L, and deionized water as the solvent.

[0080] 3) The metallized film is electroplated in multiple stages until a metal layer with a thickness of 1 μm is formed on both sides; then it is immersed in a corrosion inhibitor at 45°C for 2 minutes, rinsed with deionized water, and dried with hot air at 60°C to obtain the composite current collector. The corrosion inhibitor consists of: BTA 10 mg / L, ammonium molybdate 15 mg / L, and deionized water as the solvent.

[0081] Examples 2-5

[0082] The composite current collectors of Examples 2-5 differ from those of Example 1 in that the thickness d of the metal embedding layer 11 is different, as shown in Table 1. A schematic diagram of Example 2 is shown in Figure 1.

[0083] The preparation methods of the composite current collectors in Examples 2-5 differ from those in Example 1 in that the immersion times of the first and second chemical plating solutions in step 2) are different. The immersion times of the first chemical plating solution in Examples 2-5 are 2.5 min, 2 min, 1.6 min, and 1.0 min, respectively, and the immersion times of the second chemical plating solution in Examples 2-5 are 1.25 min, 1.5 min, 1.7 min, and 2.0 min, respectively.

[0084] Examples 6-7

[0085] The composite current collectors of Examples 6 and 7 differ from those of Example 3 in that the porosity of the polymer base film 1 is different, as shown in Table 1.

[0086] The preparation methods of the composite current collectors in Examples 6 and 7 differ from those in Example 3 in that, in step 1), the porosities of the selected PE membranes are 20% and 50%, respectively.

[0087] Examples 8-9

[0088] The composite current collectors of Examples 8 and 9 differ from those of Example 1 in that the thickness D of the metal layer 2 is different, as shown in Table 1.

[0089] The method for preparing the composite current collector in Example 8 differs from that in Example 1 in that, in step 3), the thickness of the metal layer formed on both sides of the metallized film is 1.2 μm by controlling the time of the multi-stage electroplating.

[0090] The method for preparing the composite current collector in Example 9 differs from that in Example 1 in that, in step 3), the thickness of the metal layer formed on both sides of the metallized film is 1.5 μm by controlling the time of the multi-stage electroplating.

[0091] Examples 10-11

[0092] The composite current collectors of Examples 10-11 differ from those of Example 1 in that the thickness D0 of the polymer base film layer 1 is different, as shown in Table 1.

[0093] The preparation methods of the composite current collectors in Examples 10 and 11 differ from those in Example 1 in that: in step 1), the thicknesses of the selected PE films are 3.5 μm and 4.5 μm, respectively.

[0094] Comparative Example 1

[0095] The composite current collector of Comparative Example 1 differs from the composite current collector of Example 1 in that the thickness D0 of the polymer base film layer 1 and the thickness d of the metal embedded layer 11 are different, as shown in Table 1.

[0096] The preparation method of the composite current collector in Comparative Example 1 differs from that in Example 1 in that: in step 1), the thickness of the PE film used is 4.5 μm; in step 2), it is not immersed in the first chemical plating solution, but only in the second chemical plating solution, and the immersion time is 2.5 min.

[0097] Comparative Example 2

[0098] The composite current collector of Comparative Example 2 differs from the composite current collector of Example 1 in that the thicknesses of the polymer base film layer 1 (D0), the metal layer 2 (D), and the metal embedding layer 11 (d) are different, as detailed in Table 1.

[0099] The preparation method of the composite current collector in Comparative Example 2 differs from that in Example 1 in that: in step 1), the thickness of the PE film used is 2.5 μm; in step 2), the chemical plating process involves immersing the pretreated base film in the first chemical plating solution for 3 minutes, and then immersing it in the second chemical plating solution for 1 minute; in step 3), by controlling the time of the multi-stage electroplating, the thickness of the metal layer formed on both sides is 2 μm.

[0100] Comparative Example 3

[0101] The composite current collector of Comparative Example 3 differs from the composite current collector of Example 1 in that: no metal embedding layer 11 is provided, that is, the thickness d of the metal embedding layer 11 is 0, and the porosity of the polymer base film of the polymer base film layer 1 is different, as shown in Table 1.

[0102] The preparation method of the composite current collector in Comparative Example 3 differs from that in Example 1 in that: in step 1), the porosity of the PE membrane used is 0.

[0103] Sample characterization and performance testing

[0104] 1. Cross-section and surface morphology

[0105] Images were taken using a scanning electron microscope (SEM). The surface and cross-sectional morphology of the sample were tested after gold sputtering. Gold sputtering was used to improve the conductivity of the sample and obtain clear images. The gold-plated film formed by sputtering is approximately 10–30 nm thick and does not affect the morphology observation. Furthermore, imaging was conducted under low voltage conditions to avoid burning the base film material. The surface and cross-section of the composite current collector in Example 2 are shown in Figures 2 and 3. Figure 2 shows that the chemical plating + electroplating method of this invention forms a metal embedding layer and a metal layer without damaging the polymer base film, which contributes to a significantly higher tensile strength in the resulting composite current collector compared to the polymer base film. Figure 3 shows that the chemical plating method of this invention forms a metal embedding layer on the base film, and the formation of the metal embedding layer contributes to a significantly higher tensile strength in the resulting composite current collector compared to the polymer base film.

[0106] 2. Thickness

[0107] SEM cross-sectional analysis allows for direct measurement of the thickness of the polymer base film (D0), the metal embedding layer (d), and the metal layer (D), as detailed in Table 1. The thickness d of the metal embedding layer refers to the shortest distance from the deepest copper layer embedded in the polymer base film to the surface of the polymer base film.

[0108] 3. Tensile strength

[0109] Tensile strength tests were performed on the polymer-based films and composite current collectors of each embodiment and comparative example. A Shimadzu AGS-X-10kN electronic universal testing machine was used, with a sample length of 150mm*15mm, a test interval of 8mm, and a tensile speed of 50mm / min.

[0110] 4. Peel strength

[0111] The peel strength of the composite current collectors in each embodiment and comparative example was tested. A flat composite current collector sample was cut into specimens 24 mm wide and 300 mm long. One end of the cut specimen was folded over with adhesive tape to form a folded layer approximately 12 mm long. The other end of the specimen was glued to one end of a steel plate and rolled twice with an adhesive tape roller at a speed of 600 mm / min. The specimen was then placed in an electronic peel tester with a test speed of 250 mm / min and a specimen width of 24 mm. The equipment automatically recorded the force values ​​during the peeling process and reported the peel strength of the specimen accordingly.

[0112] 5. Shear resistance test

[0113] The sheet resistance of the composite current collectors in each embodiment and comparative example was tested. A Kejing four-probe tester was used, and the correction coefficient was set according to the test requirements. After selecting the measurement category, the instrument was switched to the measurement mode. The sample was placed on the test stage, and the probe was pressed down to ensure good contact with the sample. The test results were then read.

[0114] The results of sample characterization and performance testing are shown in Table 1 below.

[0115] Table 1

[0116] In Table 1: R0 is the tensile strength of the polymer-based film, in MPa. The units of D0, D, and d are all μm. It is an intensity factor. Dimensionless unit. R m R is the tensile strength of the composite current collector, measured in MPa. X represents the improvement in tensile strength of the composite current collector relative to the tensile strength of the base film, calculated as X = ((R m -R0) / R0)*100%. Peel strength is measured in N / m. Sheet resistance is measured in mΩ / □.

[0117] As can be seen from Table 1:

[0118] The tensile strength of the composite current collectors in Examples 1-11 increased by more than 9.7% relative to the tensile strength of the base film, indicating that the strength factor of the composite current collector can be controlled. Within a certain range, the tensile strength of the composite current collector can be significantly improved relative to the tensile strength of the polymer base film. Simultaneously, the peel strength of the composite current collectors in Examples 1-11 is all above 550 N / m, indicating that adjusting the strength factor of the composite current collector can also give it good peel strength. Furthermore, adjusting the strength factor of the composite current collector... Within a certain range, composite current collectors can also have low sheet resistance (all below 17mΩ / □).

[0119] Comparing Examples 1-5, it can be seen that as d increases, the tensile strength of the composite current collector relative to the tensile strength of the base film gradually increases, the tensile strength and peel strength of the composite current collector gradually increase, and the sheet resistance gradually decreases. Among them, compared with Examples 2-5, the sheet resistance of Example 1 decreases significantly, which is due to the interconnection of the metal embedded layers on both sides of the base film in Example 1.

[0120] Comparing Examples 3 and 6-7, it can be seen that as the porosity of the base film increases, the intensity factor... The tensile strength of the composite current collector initially increases and then decreases relative to the tensile strength of the base film.

[0121] Comparing Examples 1, 8, and 9, it can be seen that as the thickness of the metal layer increases, the strength factor... As the tensile strength of the composite current collector gradually increases relative to the tensile strength of the base film, the tensile strength of the composite current collector is improved while its sheet resistance performance is reduced.

[0122] Comparing Examples 1, 10, and 11, it can be seen that as the thickness of the base film (polymer base film layer) increases, the increase in tensile strength of the composite current collector relative to the tensile strength of the base film gradually decreases, while the tensile strength and sheet resistance of the composite current collector gradually increase.

[0123] In Comparative Example 1, the strength factor was not controlled within a suitable range, the tensile strength of the composite current collector was not significantly improved relative to the tensile strength of the base film, and the peel strength of the composite current collector was insufficient.

[0124] The strength factor of Comparative Example 2 is too large. Although the tensile strength of its composite current collector is significantly improved relative to the tensile strength of the base film, the metal layer thickness is too large. This results in the composite current collector losing its advantage of being thin and light, and the manufacturing cost is high, making it unsuitable to replace traditional metal foils (such as electrolytic copper foil).

[0125] The composite current collector in Comparative Example 3 lacks a metal embedding layer, and the tensile strength of the composite current collector is only slightly improved relative to the tensile strength of the base film; moreover, its peel strength is significantly insufficient and does not meet industry requirements.

[0126] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A composite current collector, characterized in that, It includes a polymer base film layer and a metal layer disposed on at least one surface of the polymer base film layer, wherein the polymer base film layer includes a metal embedded layer in contact with the metal layer; The intensity factor of the composite current collector for The Where D is the thickness of the metal layer, D0 is the thickness of the polymer base film layer, and d is the thickness of the metal embedding layer.

2. The composite current collector according to claim 1, characterized in that, The intensity factor of the composite current collector for 3. The composite current collector according to claim 2, characterized in that, The intensity factor of the composite current collector for 4. The composite current collector according to claim 3, characterized in that, The intensity factor of the composite current collector for 5. The composite current collector according to claim 1, characterized in that, The thickness of the metal layer is: 0.5μm≤D≤1.5μm.

6. The composite current collector according to claim 5, characterized in that, The thickness of the metal layer is: 1.0μm≤D≤1.5μm.

7. The composite current collector according to claim 1, characterized in that, The thickness of the polymer-based film layer is: 2μm≤D0≤8μm.

8. The composite current collector according to claim 7, characterized in that, The thickness of the polymer-based film layer is: 3μm≤D0≤3.5μm.

9. The composite current collector according to claim 1, characterized in that, The thickness of the metal embedding layer is: 0.1μm≤d≤D0 / 2μm.

10. The composite current collector according to claim 9, characterized in that, The thickness of the metal embedding layer is: 0.1μm≤d≤1.5μm.

11. The composite current collector according to claim 1, characterized in that, The polymer material of the polymer base film layer is at least one of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, or polypropylene.

12. The composite current collector according to claim 1, characterized in that, The material of the metal layer is at least one of copper, copper alloy, nickel, nickel alloy, silver, or silver alloy.

13. The composite current collector according to claim 1, characterized in that, The metal in the metal embedding layer is at least one of copper, copper alloy, nickel, nickel alloy, silver, or silver alloy.

14. The composite current collector according to claim 1, characterized in that, The metal layer consists of two layers, which are respectively disposed on the two surfaces of the polymer base film layer.

15. The composite current collector according to claim 1, characterized in that, The polymer base film of the polymer base film layer has a porosity of 5-70%.

16. The composite current collector according to claim 15, characterized in that, The polymer base film of the polymer base film layer has a porosity of 20-50%.

17. The composite current collector according to claim 1, characterized in that, The average pore size of the polymer base film in the polymer base film layer is 20–100 nm.

18. A method for preparing a composite current collector, characterized in that, Includes the following steps: S1. The polymer base film is subjected to plasma treatment, sensitization treatment and activation treatment to obtain a pretreated polymer base film; S2. Perform chemical plating on the pretreated polymer base film to form a metal intercalation layer in the polymer base film, thereby obtaining a metallized base film; S3. Electroplating is performed on the metallized base film to form a metal layer, thus obtaining the composite current collector.

19. The preparation method according to claim 18, characterized in that, The plasma treatment in step S1 has a power of 50-200W and a time of 60-300s.

20. The preparation method according to claim 18, characterized in that, The sensitization solution used in step S1 includes the following components at the following concentrations: SnCl2 5-25 g / L and HCl 10-35 ml / L.

21. The preparation method according to claim 18 or 20, characterized in that, The sensitization treatment time in step S1 is 0.5 to 3 minutes.

22. The preparation method according to claim 18, characterized in that, The activation solution used in step S1 includes the following concentrations: PdCl2 0.5-2 g / L and HCl 8-20 ml / L.

23. The preparation method according to claim 18 or 22, characterized in that, The activation treatment time in step S1 is 0.5 to 3 minutes.

24. The preparation method according to claim 18, characterized in that, The number of times the chemical plating is performed in step S2 can be 1 or 2.

25. The preparation method according to claim 24, characterized in that, When the electroless plating is performed once, the electroless plating solution contains the following components at the following concentrations: copper sulfate 5-10 g / L, disodium EDTA 30-60 g / L, bipyridine 5-20 mg / L, sodium hydroxide 3-8 g / L, and formaldehyde 5-10 g / L; the electroless plating time is 6-8 min.

26. The preparation method according to claim 24, characterized in that, When the electroless plating is performed twice, the electroless plating sequentially includes a first electroless plating and a second electroless plating; the electroless plating solution for the first electroless plating includes the following components at the following concentrations: copper sulfate 5-10 g / L, disodium EDTA 30-60 g / L, bipyridine 5-20 mg / L, sodium hydroxide 3-8 g / L, and formaldehyde 5-10 g / L; the electroless plating solution for the second electroless plating includes the following components at the following concentrations: copper sulfate 5-15 g / L, disodium EDTA 5-10 g / L, potassium sodium tartrate 20-40 g / L, bipyridine 5-20 mg / L, sodium hydroxide 5-10 g / L, and formaldehyde 5-20 g / L.

27. The preparation method according to claim 26, characterized in that, The first electroless plating time is 1 to 3 minutes; the second electroless plating time is 1 to 2 minutes.

28. The preparation method according to claim 18, characterized in that, The electroplating process also includes a corrosion inhibition treatment step.

29. The application of the composite current collector according to any one of claims 1 to 17 in the preparation of a lithium-ion battery anode.

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