Negative current collector, method for manufacturing the same, negative electrode sheet, and secondary battery

Abstract

This application discloses a negative electrode current collector and its preparation method, a negative electrode sheet, and a secondary battery. The negative electrode current collector includes an aramid film and a metal material. The metal material is loaded on both surfaces of the aramid film and fills the pores of the aramid film. The aramid film includes a base film and aramid fibers, with the aramid fibers grown on the first surface of the base film. The aforementioned negative electrode current collector forms an asymmetric current collector structure, increasing the metallization area per unit area on the first surface. This results in more metal contacting the tabs during welding, and the rough first surface also provides a larger contact area with the tabs, achieving better welding results. In the aforementioned negative electrode current collector, the porous aramid film has complete metallization on its inner surface, resulting in better conductivity between its two sides and achieving a balance between the metal material loading and the electron / ion permeability of the current collector.

Description

Technical Field

[0001] This application relates to the field of battery current collector technology, and in particular to a negative electrode current collector and its preparation method, a negative electrode sheet, and a secondary battery. Background Technology

[0002] Lithium-ion batteries are the core power source for electric aircraft, drones, and other devices, and their energy density and safety directly affect the device's range and reliability. While traditional lithium-ion batteries are widely used, their energy density remains limited by factors such as the capacity of the positive and negative electrode active materials and the current collector structure. Developing higher energy density and safer lithium battery systems has become a core direction for the industry. Negative-electrode lithium metal batteries, by eliminating the negative electrode active material coating process, directly utilize lithium ions from the positive electrode to form a metallic lithium negative electrode in the negative electrode current collector during the first charge, theoretically potentially breaking through the energy density limits of traditional batteries.

[0003] Traditional electrodeless lithium metal batteries generally use copper foil as the negative electrode, which has the following technical drawbacks: the smooth surface of copper foil limits the contact area with the active material layer, resulting in low electron transport efficiency. Especially under high-rate charge and discharge scenarios, it is prone to local overheating and lithium dendrites piercing the separator, leading to short circuits in the battery, requiring additional pressure to suppress volume expansion; copper foil has a large unit area mass, resulting in a high overall battery mass. To address the issue of high copper foil mass, in recent years, composite current collectors obtained by metallizing copper with lightweight polymers have shown good energy density improvement effects. However, further design optimization is needed in terms of interface bonding with lithium metal and weldability.

[0004] In summary, there is an urgent need to develop a composite current collector to effectively improve the compatibility issues between lithium metal and the current collector interface, as well as the electrode tab welding issues, suppress lithium dendrite growth under high-rate charge and discharge scenarios, and increase battery cycle life, so as to adapt to the application of negative electrodeless batteries in the aerospace field. Summary of the Invention

[0005] This invention provides a negative electrode current collector and its preparation method, a negative electrode sheet, and a secondary battery to solve the technical problems of interface compatibility between lithium metal and negative electrode current collector and the inability to weld tabs to the negative electrode current collector in the prior art.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a negative electrode current collector comprising an aramid membrane and a metal material, wherein the metal material is loaded on two surfaces of the aramid membrane and fills the pores of the aramid membrane; the aramid membrane comprises a base membrane and aramid fibers, wherein the aramid fibers are grown on a first surface of the base membrane.

[0007] Furthermore, the diameter of the aramid fiber is 1.35 μm to 1.50 μm.

[0008] Furthermore, the roughness of the first surface of the base film is 2.77 to 2.94, and the roughness of the second surface of the base film opposite to the first surface is 1.83 to 1.98.

[0009] Furthermore, the loading of the metallic material in the aramid film is 1.1 mg / cm³. 2 ~5.1mg / cm 2 .

[0010] Furthermore, the metallic material is selected from one or more of copper, zinc, nickel, and silver.

[0011] Furthermore, the porosity of the aramid membrane is 30% to 80%, the pore size of the aramid membrane is 0.8 μm to 39.52 μm, and the thickness of the aramid membrane is 6.0 μm to 20.0 μm.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned negative electrode current collector, comprising the following steps: S1. The aramid membrane is activated by immersing it in an activation solution, and then the activated aramid membrane is immersed in an alkaline solution; S2. The aramid membrane processed in step S1 is laid flat on the surface of the porous membrane, and the aramid membrane and the porous membrane are placed in a Buchner funnel, with the aramid membrane located above the porous membrane. S3. Pour the plating solution into the Buchner funnel so that the plating solution flows through the aramid membrane and the porous membrane. After filtration, take out the aramid membrane after the plating solution treatment to obtain the negative electrode current collector.

[0013] Furthermore, in step S3, the filtered plating solution is circulated into the Buchner funnel for unidirectional filtration, and the plating solution treats the aramid membrane for 2 to 10 minutes.

[0014] Furthermore, the activating solution in step S1 includes a basic colloidal palladium.

[0015] In a third aspect, the present invention provides a negative electrode sheet comprising the negative current collector described above or the negative current collector prepared by the above preparation method.

[0016] In a fourth aspect, the present invention provides a secondary battery comprising the aforementioned negative electrode sheet.

[0017] The negative electrode current collector provided by this invention has a metal material filling the voids in an aramid membrane and loaded onto the surface of the aramid membrane. Aramid fibers are grown on the first surface of the base membrane, forming an asymmetric current collector structure. This increases the metallization area per unit area on the first surface, resulting in more metal contacting the electrode tabs during welding. Furthermore, the rough first surface provides a larger contact area with the electrode tabs, achieving better welding results. In addition, the porous aramid membrane in the above-mentioned negative electrode current collector is fully metallized on its inner surface, resulting in better conductivity between its two sides, achieving a balance between the metal material loading and the electron / ion permeability of the current collector. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a planar SEM image of the negative electrode current collector in Embodiment 1 of this application; Figure 2 This is a SEM image of the cross-section of the negative electrode current collector in Embodiment 1 of this application; Figure 3 The XRD diffraction patterns of the negative electrode current collectors of Example 1 and Comparative Example 2 are shown below. Figure 4 Comparison of coulombic efficiency between the half-cell using pure copper foil as the negative electrode current collector and the half-cell using Example 1 as the negative electrode current collector; Figure 5 Comparison of nucleation overpotential between the half-cell with pure copper foil as the negative electrode current collector and the half-cell with Example 1 as the negative electrode current collector; Figure 6 As the half-cell used in Example 1 as the negative electrode current collector, at 4 mAh / cm 2 Cyclic performance and coulombic efficiency at high capacity density; Figure 7 A comparison of the rate performance of a lithium-rich manganese-based positive electrode soft-pack full cell with pure copper foil as the negative electrode current collector and a lithium-rich manganese-based positive electrode soft-pack full cell with Example 1 as the negative electrode current collector. Figure 8 Comparison of the cycling performance of a lithium-rich manganese-based positive electrode soft-pack full cell with pure copper foil as the negative electrode current collector and a lithium-rich manganese-based positive electrode soft-pack full cell with Example 1 as the negative electrode current collector at 0.3C rate. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] A first aspect of this application provides a negative electrode current collector, comprising an aramid membrane and a metal material, wherein the metal material is loaded on both surfaces of the aramid membrane and fills the pores of the aramid membrane; the aramid membrane comprises a base membrane and aramid fibers, wherein the aramid fibers are grown on the first surface of the base membrane. Specifically, the diameter of the aramid fibers is 1.35 μm to 1.50 μm.

[0022] In the negative electrode current collector of this application, metal material fills the pores of the aramid membrane and is loaded onto the surface of the aramid membrane. Aramid fibers are grown on the first surface of the base membrane, forming an asymmetric current collector structure. This increases the metallization area per unit area of ​​the first surface, resulting in more metal contacting the electrode tabs during welding. Furthermore, the rough first surface provides a larger contact area with the electrode tabs, achieving better welding results. Additionally, the complete metallization of the porous aramid membrane surface in the negative electrode current collector improves conductivity between its two sides, achieving a balance between metal material loading and electron / ion permeability of the current collector. In this application embodiment, the surface where aramid fibers are grown is defined as the first surface.

[0023] The negative electrode current collector of this application embodiment, by means of the 3D structure of metal material and aramid film, can effectively reduce volume expansion, improve lithium-ion transport efficiency, and thus improve battery cycle performance and rate performance.

[0024] In this embodiment, the porosity of the aramid membrane is strictly controlled to be between 30% and 80% to avoid problems such as poor local conductivity and dendrite hotspots caused by uneven pore size. This porosity can control the porosity of the negative electrode current collector. The pore size of the aramid membrane is 0.8 μm to 39.52 μm, and the thickness is 6.0 μm to 20.0 μm.

[0025] In some embodiments, the roughness of the first surface of the base film is 2.77–2.94, and the roughness of the second surface of the base film opposite to the first surface is 1.83–1.98. In the embodiments of this application, the two surfaces of the base film have different roughnesses, which enables a more secure welding to the tabs and improves electronic conductivity; the larger surface area of ​​the first surface is beneficial for uniform electric field and reduces non-uniform lithium deposition. The rougher first surface is microscopically porous and has a certain three-dimensional structure, which helps to alleviate the volume expansion of lithium deposition and improve the cycle stability of the battery.

[0026] In some embodiments, the loading of the metallic material in the aramid film is 1.1 mg / cm³. 2 ~5.1mg / cm 2 In this embodiment, the amount of metal per unit area of ​​the aramid membrane affects the welding effect, and the welding effect is optimal when the metal material load is within the aforementioned range. Furthermore, excessively high metal content per unit area may lead to pore blockage in the aramid membrane, reduced ion transport rate, and increased weight per unit area, thus reducing battery energy density.

[0027] Specifically, the aforementioned metallic materials are selected from one or more of copper, zinc, nickel, and silver.

[0028] A second aspect of this application provides a method for preparing the above-mentioned negative electrode current collector, comprising the following steps: S1, immersing an aramid membrane in an activation solution for activation, and then immersing the activated aramid membrane in an alkaline solution; S2, spreading the aramid membrane treated in step S1 flat on the surface of a porous membrane, and placing the aramid membrane and the porous membrane in a Buchner funnel, with the aramid membrane positioned above the porous membrane; S3, pouring a plating solution into the Buchner funnel to allow the plating solution to flow through the aramid membrane and the porous membrane, filtering, and then removing the aramid membrane after plating solution treatment to obtain the negative electrode current collector.

[0029] The method for preparing the negative electrode current collector in this embodiment utilizes electroless plating to not only load metal materials onto the surface of the aramid membrane but also fill the pores within it. Unlike conventional electroless plating processes, this application introduces a unidirectional filtration step during the plating process. This unidirectional liquid flow achieves the asymmetric structure of the aramid membrane; that is, the unidirectional flow causes the aramid fibers on the first surface to form a certain angle with the base membrane plane, without affecting the second surface as described above. Furthermore, it improves the uniformity of metal deposition within the complex internal structure of the aramid membrane, optimizes the potential for membrane clogging, maintains appropriate permeability, and facilitates subsequent ion transport in the battery.

[0030] In the negative electrode current collector of this application embodiment, a unidirectional vacuum filtration electroless plating method is used in the preparation process. This not only makes the metallization of the inner surface of the aramid membrane more complete, that is, the conductivity between the two sides is better; at the same time, this liquid flow is a dynamic deposition process, which maintains the permeability of the aramid membrane, so that it can pass well through the electrolyte in the battery, that is, it has good ion permeability.

[0031] In this embodiment, the plating solution is a commonly used copper plating solution in a formaldehyde system. The porous membrane can be filter paper, which serves as the substrate material for preparing the negative electrode current collector.

[0032] In some embodiments, in step S3, the filtered plating solution is circulated into a Buchner funnel for further filtration, and the plating solution treatment time for the aramid membrane is 2 to 10 minutes. In the embodiments of this application, the longer the plating solution treatment time, the more metal will be loaded onto the aramid membrane; the above-mentioned treatment time range is preferred, as excessive time may cause blockage of micropores due to excessive metal loading, reducing the permeability between the two sides of the aramid membrane.

[0033] A third aspect of this application provides a negative electrode sheet, including the aforementioned negative current collector.

[0034] A fourth aspect of the embodiments of this application provides a secondary battery, including the above-described negative electrode sheet.

[0035] The present application will be further described below through specific embodiments. All reagents in the following embodiments are commercially available.

[0036] Example 1 A negative electrode current collector includes an aramid membrane and copper, wherein copper is loaded on both surfaces of the aramid membrane and fills the pores of the aramid membrane. The aramid membrane includes a base membrane and aramid fibers, wherein the aramid fibers are grown on the first surface of the base membrane, and the diameter of the aramid fibers is 1.35 μm to 1.50 μm.

[0037] The roughness of the first surface of the base film is 2.89 (multi-point average), and the roughness of the second surface of the base film opposite the first surface is 1.90 (multi-point average). The copper loading in the aramid film is 2.9 mg / cm². 2 The porosity of the aramid membrane is 60%, and the pore size of the aramid membrane is 0.8μm to 36.82μm; the thickness of the aramid membrane is 6.5μm.

[0038] The above-mentioned method for preparing the negative electrode current collector includes the following steps: 1. Cut and clean, removing oil: Cut the aramid membrane into rectangles 15cm long and 8cm wide using a utility knife; then place it in pure water and sonicate for 10 minutes.

[0039] 2. Activation and acceleration: Immerse the above-treated aramid membrane in a basic colloidal palladium activation solution for 2 minutes (solution temperature 45℃, volume 500mL), and then rinse with deionized water. Then immerse it in a 5% sodium hydroxide solution for 2 minutes (solution temperature 45℃, volume 500mL).

[0040] 3. Preparation of plating solution: Mix 100 mL of 14 g / L copper sulfate solution with 100 mL of a mixture of sodium hydroxide, potassium sodium tartrate, and sodium carbonate. The concentrations of sodium hydroxide, potassium sodium tartrate, and sodium carbonate in this mixture are 9 g / L, 44.5 g / L, and 4.2 g / L, respectively. After mixing, add 20 mL of formaldehyde, followed by 12 mL of 0.1 g / L potassium ferrocyanide solution to obtain the plating solution.

[0041] 4. Chemical Plating: Spread the aramid membrane treated in step 2 evenly on the surface of a porous membrane with a pore size of 1 mm, and then place both in a Buchner funnel, with the aramid membrane on top of the porous membrane. Pour the plating solution prepared in step 3 into the Buchner funnel, and use a circulating pump to filter the solution below the funnel. The filtered solution is then returned to the Buchner funnel for circulation, ensuring unidirectional flow of the solution within the aramid membrane. Control the filtration speed, maintain the solution temperature at 45℃, and the chemical plating time at 5 minutes.

[0042] 5. Take out the aramid membrane after step 4, wash it 3 times with deionized water, wash it once with anhydrous ethanol, and dry it completely to obtain the above negative electrode current collector.

[0043] The negative electrode current collector was characterized using scanning electron microscopy, and its planar SEM image is shown below. Figure 1 Cross-sectional SEM image reference Figure 2 .from Figure 1 As can be seen, the negative electrode current collector has a 3D fibrous through-pore structure, composed of filamentous fibers. From Figure 2 As can be seen, the thickness of the negative electrode current collector is approximately 6.5 μm.

[0044] Example 2 The negative electrode current collector in this embodiment is basically the same as that in Embodiment 1, except that the metal material is zinc.

[0045] The preparation method of the negative electrode current collector in this embodiment is basically the same as that in Example 1, except that the time for treating the aramid film with the plating solution, i.e., the time for chemical plating, is 2 minutes.

[0046] Example 3 The negative electrode current collector in this embodiment is basically the same as that in Embodiment 1, except that the metal material is aluminum.

[0047] The preparation method of the negative electrode current collector in this embodiment is basically the same as that in Example 1, except that the time for treating the aramid film with the plating solution, i.e., the time for chemical plating, is 10 minutes.

[0048] Comparative Example 1 The preparation method of the negative electrode current collector in this comparative example is basically the same as that in Example 1, except that the chemical plating method of vacuum filtration cycle is changed to immersing the treated aramid film in the plating solution for 5 minutes.

[0049] Comparative Example 2 The method for preparing a negative electrode current collector includes the following steps: 1. The coating is completed using a magnetron sputtering coating machine. Turn on the instrument, set the cooling water temperature, start the air compressor, set the pressure reducing valve to 0.2 MPa, and open the vent valve to release pressure and vent air from the chamber.

[0050] 2. Fix the aramid membrane on the rotating substrate stage, turn on the vacuum pump, and when the vacuum gauge reading is below 5 Pa, start the molecular pump to evacuate to a magnetron sputtering background vacuum of 8.0 × 10⁻⁶. −4 .

[0051] 3. Set the substrate rotation speed to 15 r / min, the flow limiting valve angle to 0 degrees, the argon flow rate to 8 sccm, the vacuum sputtering pressure to 0.3 Pa, the sputtering power corresponding to the Cu target to 100 W, start the sputtering power supply, and set the dual-target thin film deposition rate to 4 a / s.

[0052] 4. The film thickness is calculated by accumulating the sputtering time. The sputtering time is set to 60 min, at which time the sputtered Cu thickness is approximately 2 μm.

[0053] The negative electrode current collectors of Examples 1 to 3, Comparative Examples 1 and 2, and pure copper foil were used as negative electrodes to assemble electrodeless lithium metal batteries, and their electrochemical performance was tested. The test results are shown in Table 1. Additionally, Figure 3 The XRD diffraction patterns of the negative electrode current collectors of Example 1 and Comparative Example 2 show that the surface of the aramid film was successfully loaded with metallic copper in both methods. Figure 4 The coulombic efficiency of the half-cell with pure copper foil as the negative electrode current collector was compared with that of the half-cell with Example 1 as the negative electrode current collector. Compared with pure copper foil, the coulombic efficiency of Example 1 was improved by 0.31%, and the cycle life was increased from less than 50 cycles to more than 200 cycles.

[0054] Figure 5 The nucleation overpotential of the half-cell with pure copper foil as the negative electrode current collector was compared with that of the half-cell with Example 1 as the negative electrode current collector. Compared with pure copper foil, the nucleation overpotential of Example 1 was significantly reduced, which proves that the excellent surface properties of Example 1 reduced the nucleation barrier and the lithium deposition was more uniform.

[0055] Figure 6 As the half-cell used in Example 1 as the negative electrode current collector, at 4 mAh / cm 2 The cycling performance and coulombic efficiency diagram at high capacity density show that the average coulombic efficiency is increased to 99.02%, and no coulombic efficiency fluctuation is observed after more than 80 stable cycles, proving that Example 1 has a very high possibility of being directly applied as a negative electrode current collector to a negative electrode-less lithium metal battery.

[0056] Figure 7This paper compares the rate performance of a lithium-rich manganese-based pouch cell with pure copper foil as the negative electrode current collector with that of Example 1 with pure copper foil as the negative electrode current collector. As shown in the figure, Example 1 exhibits significantly superior capacity performance at 0.1C, 0.3C, 0.5C, 1C, and 2C rates compared to pure copper foil, and it can cycle stably at 1C, demonstrating that the rate performance of Example 1 is superior to that of pure copper foil.

[0057] Figure 8 A comparison of the cycling performance of a lithium-rich manganese-based pouch cell with pure copper foil as the negative electrode current collector and a lithium-rich manganese-based pouch cell with Example 1 as the negative electrode current collector at 0.3C rate. As shown in the figure, the capacity retention of the pure copper foil cell drops below 70% after only about 30 cycles, while Example 1 retains approximately 80% of its capacity after more than 200 cycles. This demonstrates that the cycling performance of Example 1 is superior to that of the pure copper foil cell.

[0058] The battery assembly process is as follows: The process of preparing a lithium copper half-cell is as follows: the negative electrode current collector and the pure copper current collector are cut into circular pieces with a diameter of 14mm using a punching machine. The button half-cell is assembled in the following order: negative electrode shell - spring piece - gasket - 14mm diameter lithium metal - separator - negative electrode current collector or pure copper current collector - electrolyte - positive electrode shell. The cell is then charged and discharged according to different lithium deposition areal densities.

[0059] The process of preparing a negative electrode-free soft-pack full battery is as follows: The soft-pack battery cells are assembled, injected with electrolyte, and packaged using a Z-shaped stacking process in the order of positive electrode-separator-negative electrode (referring to the negative electrode current collector). After 0.1C formation, constant current and constant voltage charge-discharge cycles are performed at different rates.

[0060] Table 1 Performance results of negative electrode current collector assembled batteries in Examples 1 to 3 and Comparative Examples 1 and 2 Table 1 shows that, comparing Examples 1 to 3, the electroless plating time directly affects the density of the metal material in the aramid film (i.e., the metal loading). In Example 1, the metal material density was optimal, maintaining good conductivity while preserving the porosity within the aramid film, providing a good ion transport pathway, and thus exhibiting the best electrochemical performance. In Example 3, the higher metal material density in the negative electrode current collector reduced the porosity within the aramid film, decreased the ion transport rate, and increased the weight of the negative electrode current collector, thus lowering the theoretical energy density of the battery. In Example 2, the lower metal material density in the negative electrode current collector reduced the overall weight and achieved the highest theoretical energy density, but slightly reduced conductivity and a relatively slight decrease in electrochemical performance.

[0061] In Table 1, pure copper foil was used as the negative electrode current collector. Although the copper surface density was close to that of Example 3, its surface was flat and the rigidity of copper was high, which could not provide a good effect for the uniform deposition of lithium. Therefore, its electrochemical performance was the worst.

[0062] Compared with Comparative Examples 1 and 2, Examples 1 to 3 show that the negative electrode current collector in Example 1 has an asymmetric structure (the first surface is relatively loose, and the second surface is relatively flat). In Comparative Example 1, the negative electrode current collector prepared using conventional chemical plating methods has relatively flat surfaces on both sides, which cannot provide a larger bonding area for welding. Therefore, its welding with the tab is not strong, leading to subsequent degradation of electrochemical performance. In Comparative Example 2, the negative electrode current collector prepared by magnetron sputtering has copper mostly distributed on the surface of the aramid film, with low metallization and uneven distribution of its internal pores, making it unable to form a tight bond when welded to the tab.

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A negative electrode current collector, characterized in that, The negative electrode current collector includes an aramid membrane and a metal material. The metal material is loaded on both surfaces of the aramid membrane and fills the pores of the aramid membrane. The aramid membrane includes a base membrane and aramid fibers. The aramid fibers are grown on the first surface of the base membrane.

2. The negative electrode current collector according to claim 1, characterized in that, The roughness of the first surface of the base film is 2.77–2.94, and the roughness of the second surface of the base film opposite to the first surface is 1.83–1.98; and / or, The diameter of the aramid fiber is 1.35μm to 1.50μm.

3. The negative electrode current collector according to claim 1 or 2, characterized in that, The loading of the metallic material in the aramid film is 1.1 mg / cm³. 2 ~5.1mg / cm 2 .

4. The negative electrode current collector according to claim 1 or 2, characterized in that, The metallic material is selected from one or more of copper, zinc, nickel, and silver.

5. The negative electrode current collector according to claim 1 or 2, characterized in that, The aramid membrane has a porosity of 30% to 80%, a pore size of 0.8 μm to 39.52 μm, and a thickness of 6.0 μm to 20.0 μm.

6. The method for preparing the negative electrode current collector according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. The aramid membrane is activated by immersing it in an activation solution, and then the activated aramid membrane is immersed in an alkaline solution; S2. The aramid membrane processed in step S1 is laid flat on the surface of the porous membrane, and the aramid membrane and the porous membrane are placed in a Buchner funnel, with the aramid membrane located above the porous membrane. S3. Pour the plating solution into the Buchner funnel so that the plating solution flows through the aramid membrane and the porous membrane. After filtration, take out the aramid membrane after the plating solution treatment to obtain the negative electrode current collector.

7. The method for preparing the negative electrode current collector according to claim 6, characterized in that, In step S3, the filtered plating solution is circulated into the Buchner funnel for unidirectional filtration, and the plating solution treats the aramid membrane for 2 to 10 minutes.

8. The method for preparing the negative electrode current collector according to claim 6 or 7, characterized in that, The activation solution in step S1 includes basic colloidal palladium.

9. A negative electrode sheet, characterized in that, The negative electrode current collector includes the negative electrode current collector as described in any one of claims 1 to 5 or the negative electrode current collector prepared by the preparation method described in any one of claims 6 to 8.

10. A secondary battery, characterized in that, Includes the negative electrode sheet as described in claim 9.

Images