Copper foil current collector, preparation method and electrode plate

Abstract

The invention provides a copper foil current collector, a preparation method and an electrode plate, and belongs to the technical field of batteries. The preparation method of the copper foil current collector comprises the following steps: providing copper powder; mixing the copper powder with an N-methyl pyrrolidone solvent and polyacrylonitrile (PAN) to obtain a membrane casting solution; performing film pressing and curing treatment on the film casting solution to obtain a 3D porous copper film green body; performing solid-phase sintering on the 3D porous copper film green body to obtain the 3D porous copper film; preparing a nano active material; and processing the nano active material and the 3D porous copper film to obtain the copper foil current collector. According to the scheme, the loading capacity of the nano active material is improved, electrolyte infiltration is facilitated, the contact area of an electrode and electrolyte is increased, the transport distance of electrons / ions in the electrochemical process is shortened, the electrochemical power is enhanced, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and particularly to a copper foil current collector, a preparation method thereof, and an electrode sheet. Background Art

[0002] As a carrier of electrode active substances in lithium ion batteries, the current collector can collect the current generated by the active substances and output it externally. Therefore, the current collector and the active substances should be in close contact and have a small internal resistance. The traditional two-dimensional planar copper foil current collector is prone to the shedding of nano-active materials, resulting in the formation of a large amount of lithium deposition. The insulating and inactive corrosion film generated on its surface will increase the internal resistance of the battery. In addition, the traditional process uses an inactive and insulating binder, which not only makes the electrode preparation process lengthy, but also cannot provide a buffer space for the volume expansion of nano-active materials during charge and discharge; its adhesive force is not sufficient to support a large volume expansion, ultimately causing the separation of nano-active substances from the current collector, reducing the battery capacity and the battery cycle life. Therefore, the traditional planar current collector can no longer meet the use requirements of current electrode materials, and it is necessary to optimize the structure of the current collector. Summary of the Invention

[0003] The present invention provides a copper foil current collector, a preparation method thereof, and an electrode sheet, which solve the problem of reduced battery cycle life caused by the traditional two-dimensional planar copper foil current collector.

[0004] To solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A preparation method of a copper foil current collector, the method comprising:

[0006] Providing copper powder;

[0007] Mixing the copper powder with an N-methylpyrrolidone solvent and polyacrylonitrile PAN to obtain a casting solution;

[0008] Performing film pressing and curing treatments on the casting solution to obtain a 3D porous copper film green body;

[0009] Performing solid-phase sintering on the 3D porous copper film green body to obtain a 3D porous copper film;

[0010] Preparing nano-active materials;

[0011] Treating the nano-active materials and the 3D porous copper film to obtain a copper foil current collector.

[0012] Optionally, mixing the copper powder with an N-methylpyrrolidone solvent and polyacrylonitrile PAN to obtain a casting solution, comprising:

[0013] Mix copper powder of a first preset quality with an N-methylpyrrolidone solvent of a second preset quality to dissolve the copper powder to form a mixed solution;

[0014] Stir and mix polyacrylonitrile PAN of a third preset quality with the mixed solution to form a casting solution.

[0015] Optionally, press and cure the casting solution to obtain a green body of a 3D porous copper film, including:

[0016] Pour the casting solution onto a flat object and use a film scraper to scrape the casting solution to form a flat film on the flat object;

[0017] Place the flat object with the flat film in distilled water for a conversion reaction, and after the conversion reaction ends, dry and press the flat film to obtain a green body of a 3D porous copper film.

[0018] Optionally, perform solid-phase sintering on the green body of the 3D porous copper film to obtain a 3D porous copper film, including:

[0019] Place the green body of the 3D porous copper film in a furnace, heat it to a first preset temperature at a first preset heating rate and hold for a first period of time;

[0020] Cool the furnace. When the temperature in the furnace drops below a second preset temperature, heat it to the second preset temperature at a second preset heating rate and introduce argon;

[0021] When the temperature in the furnace is within a first temperature range, introduce hydrogen and hold for a second period of time;

[0022] Cool the furnace. When the temperature in the furnace drops below the second preset temperature, turn off hydrogen and introduce argon. After the temperature in the furnace drops to room temperature, obtain the 3D porous copper film.

[0023] Optionally, the preparation of the nano-active material includes:

[0024] Perform ball milling on the graphite raw material to obtain nano-scale graphite;

[0025] Pour the nano-scale graphite, carbon black and polyvinylidene fluoride into an N-methylpyrrolidone solvent and stir to obtain the nano-active material.

[0026] Optionally, the treatment of the nano-active material and the 3D porous copper film to obtain a copper foil current collector includes:

[0027] Put the 3D porous copper film into the nano-active material for ultrasonic treatment to obtain an electrode sheet raw material;

[0028] Remove the excess nano-active material on the surface of the electrode sheet raw material, and place it in a vacuum drying oven for drying to obtain the 3D porous copper foil current collector.

[0029] An embodiment of the present invention further provides a copper foil current collector, which is prepared by the above method. Among them, active substances are distributed on the surface of the copper foil current collector; the interior of the copper foil current collector is a 3D porous structure, and the 3D porous structure is filled with active substances.

[0030] Optionally, the pore diameter of the pores is 3 μm to 10 μm.

[0031] Optionally, the active substance is the nano-active material, and the carbon element content of the nano-active material is more than 98%.

[0032] An embodiment of the present invention further provides an electrode sheet, including the above copper foil current collector, and the copper foil current collector is a copper foil current collector with a preset thickness.

[0033] The beneficial effects of the above technical solutions of the present invention are as follows:

[0034] By mixing the copper powder with N-methylpyrrolidone solvent and polyacrylonitrile PAN, a casting solution is obtained; the casting solution is subjected to film pressing and curing treatments to obtain a 3D porous copper film green body; the 3D porous copper film green body is subjected to solid-phase sintering to increase the porosity and obtain a 3D porous copper film; a nano-active material is prepared; the nano-active material and the 3D porous copper film are processed to obtain a copper foil current collector; active substances are distributed on the surface and internal pores of the current collector at the same time, increasing the loading amount of the nano-active material, and the porosity of the 3D porous structure is relatively high, which is beneficial to the infiltration of the electrolyte and provides a large electrode-electrolyte contact area, shortening the transport distance of electrons / ions in the electrochemical process, enhancing the electrochemical driving force, and increasing the battery cycle life. Description of the Drawings

[0035] Figure 1 It is a schematic flow chart of the preparation method of the copper foil current collector according to the embodiment of the present invention. Detailed Embodiments

[0036] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as a limitation to the present invention.

[0037] As Figure 1 shown, the present invention provides a preparation method of a copper foil current collector, including:

[0038] Step 11, providing copper powder;

[0039] Step 12: Mix the copper powder with N-methylpyrrolidone solvent and polyacrylonitrile (PAN) to obtain a casting solution.

[0040] Step 13: Perform film pressing and curing on the casting solution to obtain a green body of the 3D porous copper film.

[0041] Step 14: Perform solid-phase sintering on the green body of the 3D porous copper film to obtain the 3D porous copper film.

[0042] Step 15: Prepare the nano active material.

[0043] Step 16: Treat the nano active material and the 3D porous copper film to obtain a copper foil current collector.

[0044] In this embodiment of the present invention, by mixing the copper powder with N-methylpyrrolidone solvent and polyacrylonitrile (PAN) to obtain a casting solution; performing film pressing and curing on the casting solution to obtain a green body of the 3D porous copper film; performing solid-phase sintering on the green body of the 3D porous copper film to obtain the 3D porous copper film; preparing the nano active material; treating the nano active material and the 3D porous copper film to obtain a copper foil current collector; the active substance is distributed on the surface and internal pores of the current collector at the same time, improving the loading amount of the nano active material, and the 3D porous structure is beneficial to the infiltration of the electrolyte and provides a large electrode-electrolyte contact area, shortening the transport distance of electrons / ions in the electrochemical process and enhancing the electrochemical driving force.

[0045] In some embodiments of the present invention, Step 12 may include:

[0046] Step 121: Mix a first preset mass of copper powder with a second preset mass of N-methylpyrrolidone solvent to dissolve the copper powder to form a mixed solution.

[0047] Step 122: Stir and mix a third preset mass of polyacrylonitrile (PAN) with the mixed solution to form a casting solution.

[0048] In this embodiment, 35 g of dried Cu powder can be weighed into a three-necked flask, and then 25 g of N-methylpyrrolidone solvent is poured in and stirred to dissolve it. After the Cu powder and the N-methylpyrrolidone solvent are mixed evenly, 1 g of polyacrylonitrile (PAN) is weighed and slowly poured in, and stirring is continued until a casting solution with appropriate viscosity for film scraping and stability is formed.

[0049] In some embodiments of the present invention, Step 13 may include:

[0050] Step 131: Pour the casting solution onto a flat object, and use a film scraper to scrape the casting solution to form a flat film on the flat object.

[0051] Step 132: Place the planar object with the planar film in distilled water for a conversion reaction. After the conversion reaction ends, dry and press the planar film to obtain a green body of the 3D porous copper film.

[0052] In this embodiment, the casting solution is poured onto the dried glass plate, and a flat film is scraped out using a film scraper and quickly placed in distilled water for a solvent-nonsolvent phase conversion reaction. After the exchange ends, through drying and pressing, a green body of the 3D porous copper film with a microporous structure and certain strength can be obtained.

[0053] In some embodiments of the present invention, step 14 may include:

[0054] Step 141: Place the green body of the 3D porous copper film in a furnace, and raise the temperature to a first preset temperature at a first preset heating rate and hold for a first period of time.

[0055] Step 142: Perform a temperature reduction treatment on the furnace. When the temperature in the furnace drops below a second preset temperature, raise the temperature to the second preset temperature at a second preset heating rate and introduce argon.

[0056] Step 143: When the temperature in the furnace is within a first temperature range, introduce hydrogen and hold for a second period of time.

[0057] Step 144: Perform a temperature reduction treatment on the furnace. When the temperature in the furnace drops below the second preset temperature, turn off the hydrogen and introduce argon. After the temperature in the furnace drops to room temperature, the 3D porous copper film is obtained.

[0058] In this embodiment, the prepared green body of the 3D porous copper film is placed in a tube furnace for sintering. The heating sequence during the oxidation process is as follows: the temperature in the furnace is raised to 750°C at a heating rate of 15°C / min and held for 2.5 h, and then cooled with the furnace. The heating sequence during the reduction process is as follows: when the temperature in the furnace is below 300°C, raise the temperature to 300°C at a heating rate of 10°C / min and introduce 200 sccm of argon. When the temperature in the furnace is between 300°C and 750°C, introduce 150 sccm of hydrogen and hold for 1 h. Finally, cool with the furnace. When the temperature in the furnace drops to 300°C, turn off the hydrogen and introduce 200 sccm of argon. After the temperature in the furnace drops to room temperature, take out the sample to obtain the 3D porous copper film.

[0059] In some embodiments of the present invention, step 15 may include:

[0060] Step 151: Perform ball milling on the graphite raw material to obtain nanoscale graphite.

[0061] Step 152: Pour the nanoscale graphite, carbon black, and polyvinylidene fluoride into an N-methylpyrrolidone solvent and stir to obtain a nanoactive material.

[0062] In this embodiment, commercial graphite (15 μm) was placed in a vacuum drying oven and dried at 60 °C for 12 h; 30 g of the dried graphite was weighed, and ball milling was carried out for 50 h with argon as the protective gas according to a ball-to-material ratio of 8:1 to prepare nanoscale graphite.

[0063] In some embodiments of the present invention, step 16 may include:

[0064] Step 161, putting the 3D porous copper film into the nano-active material for ultrasonic treatment to obtain the raw material of the electrode sheet;

[0065] Step 162, removing the excess nano-active material on the surface of the electrode sheet raw material and drying it in a vacuum drying oven to obtain the 3D porous copper foil current collector.

[0066] Furthermore, it may further include:

[0067] Step 163, using the prepared 3D porous copper film as the current collector to load the nano-active material, and by adjusting the slurry concentration and coating process of the active material, the loading amount of the nano-active material is increased;

[0068] Step 164, by adjusting the rolling process of the electrode, further improving the tap density of the nano-active material and the uniformity of the distribution of the nano-active material, and preparing a composite electrode with excellent electrochemical performance.

[0069] In this embodiment, the ball-milled graphite, carbon black, and polyvinylidene fluoride were weighed according to a mass ratio of 9:3:1 and placed in a clean beaker. After adding N-methylpyrrolidone solvent, magnetic stirring was carried out to form a slurry. After the slurry was stirred evenly, it was poured into a watch glass. The prepared 3D porous copper film was weighed on an electronic balance and recorded, and then put into the watch glass for ultrasonic treatment to form an electrode sheet. The electrode sheet was taken out and the excess electrode slurry on the surface was removed, and then dried in a vacuum drying oven at 100 °C for 24 h.

[0070] Step 165, adjusting the distance between the two roller shafts of the roll press, and rolling the prepared electrode sheet. As the distance between the two shafts gradually shortens, the thickness of the electrode sheet gradually decreases. After rolling to an appropriate thickness, an electrode with flexibility and uniform thickness can be obtained.

[0071] In the above embodiments of the present invention, by regulating the ratio of the casting solution and the solid-phase sintering parameters, a 3D porous copper film with different thicknesses, uniform pore size distribution, pore sizes ranging from 3 to 10 μm, and good mechanical strength and flexibility macroscopically is prepared; the particle size of commercial graphite is reduced by ball milling to prepare nano-active materials; the prepared 3D porous copper film is used as a current collector to load nano-active materials, and by adjusting the slurry concentration and coating process of the nano-active materials, the loading amount of the nano-active materials is increased; by adjusting the rolling process of the electrode, the tap density of the nano-active materials and the uniformity of the distribution of the nano-active materials are further improved, and a composite electrode with excellent electrochemical performance is prepared. Compared with the traditional copper foil current collector, the 3D porous copper foil current collector has excellent electrochemical cycle stability and rate performance. At the same time, the process for preparing the 3D porous copper foil current collector is simple, low-cost, green and pollution-free, and no pollutants are discharged during the preparation process, and industrial large-scale production can be realized.

[0072] An embodiment of the present invention also provides a copper foil current collector, which is obtained by using the preparation method as Figure 1 shown, wherein active substances are distributed on the surface of the copper foil current collector; the interior of the copper foil current collector is a 3D porous structure, and the 3D porous structure is filled with active substances.

[0073] In some embodiments of the present invention, the thickness of the copper foil current collector is 45 μm to 80 μm, and the pore diameter of the pores is 3 μm to 10 μm.

[0074] In some embodiments of the present invention, the active substance is the nano-active material, and the carbon element content of the nano-active material is more than 98%.

[0075] An embodiment of the present invention also provides an electrode sheet, including the above copper foil current collector, and the copper foil current collector is a copper foil current collector with a preset thickness.

[0076] In the above embodiments of the present invention, the specific requirements for the copper powder, polyacrylonitrile PAN, N-methylpyrrolidone, etc. are shown in Table 1.

[0077] Table 1 Material names and parameters

[0078] Name Use Performance Parameters Copper Powder (Cu, 15μm) Raw Material for 3D Porous Copper Film Purity ≥ 98.0% Polyacrylonitrile PAN Binder, Dispersant Purity ≥ 98.0% N-Methylpyrrolidone Solvent Purity ≥ 99.0% Graphite Active Material Purity ≥ 98.0% Carbon Black Conductive Agent Purity ≥ 98.0% Polyvinylidene Fluoride Binder Purity ≥ 98.0% Copper Foil Current Collector Thickness ≤ 9μm Separator Paper Battery Separator Thickness ≤ 25μm Lithium Sheet Counter Electrode Purity ≥ 99.9% Absolute Ethanol Cleaning Agent Purity ≥ 99.7% Argon Protective Gas Purity ≥ 99.90% Hydrogen Reducing Gas Purity ≥ 99.90%

[0079] Example 1

[0080] This example provides a preparation method for a 3D porous copper foil current collector electrode sheet, including:

[0081] (1) Prepare a 3D porous copper film green body

[0082] Place instruments such as copper powder, polyacrylonitrile, and a three-necked flask in a vacuum drying oven and pre-treat them by drying at 60 °C for 12 h; among them, the purity of the copper powder is greater than 98%, and the concentration of the polyacrylonitrile is 1.5 mg / mL.

[0083] Weigh 35 g of the dried copper powder and place it in a three-necked flask. Pour 25 g of N-methylpyrrolidone solvent and stir to dissolve it, so that the copper powder is dissolved to form a casting solution; among them, the concentration of the N-methylpyrrolidone solvent is 25 mg / mL.

[0084] Weigh 1 g of the polyacrylonitrile and slowly pour it into the casting solution, and continue to stir until a suspension with appropriate viscosity for film scraping and stability is formed.

[0085] Pour the suspension onto a dried flat glass plate, use a film scraper to scrape out a flat film, and quickly place it in distilled water for a solvent-nonsolvent phase inversion reaction. After the conversion reaction is completed, it is dried and pressed to obtain a green body of a 3D porous copper film with a microporous structure and a certain strength.

[0086] (2) Solid-phase sintering of 3D porous copper film

[0087] Place the prepared green body of the 3D porous copper film in a tube furnace for sintering. The sintering includes an oxidation process and a reduction process.

[0088] The heating process during the oxidation process is as follows: the temperature in the tube furnace is heated to 750 °C at a heating rate of 15 °C / min and held for 2.5 h, and then cooled naturally.

[0089] The heating process during the reduction process is as follows: when the temperature in the tube furnace is below 300 °C, it is heated to 300 °C at a heating rate of 10 °C / min and argon is introduced at 200 sccm; when the temperature in the tube furnace is between 300 °C and 750 °C, hydrogen is introduced at 150 sccm and held for 1 h, and then cooled naturally; when the temperature in the tube furnace drops to 300 °C, the introduction of hydrogen is stopped and argon is introduced at 200 sccm; after the temperature drops to room temperature, the sample is taken out to obtain a 3D porous copper film.

[0090] (3) Preparation of nano-active material

[0091] Place graphite materials with a particle diameter greater than 15 μm and a purity greater than 98% in a vacuum drying oven and dry them at 60 °C for 12 h.

[0092] Weigh 30 g of the dried graphite material and ball-mill it for 50 h at a ball-to-material ratio of 8:1 with argon as the protective gas to obtain a nano-scale graphite material with a particle diameter less than 0.5 μm. The nano-scale graphite material is the nano-active material.

[0093] (4) Preparation of 3D porous copper foil current collector

[0094] Weigh the materials according to the mass ratio of 69.23% of nano-graphite material, 23.08% of carbon black and 7.69% of polyvinylidene fluoride, place them in a clean beaker, add N-methylpyrrolidone solvent and then stir magnetically to form a slurry;

[0095] After the slurry is stirred evenly, pour it into a petri dish, weigh 50 g of the 3D porous copper film and put it into the petri dish for ultrasonic treatment to form an electrode sheet;

[0096] Take out the electrode sheet, remove the excess slurry on the surface, and place it in a vacuum drying oven to dry at a temperature of 100 °C for 24 h to obtain the 3D porous copper foil current collector.

[0097] (5) Preparation of 3D porous copper foil current collector electrode sheet

[0098] Place the 3D porous copper foil current collector between the two roller shafts of a roller press;

[0099] Adjust the distance between the two roller shafts of the roller press and roll the 3D porous copper foil current collector;

[0100] As the distance between the two shafts gradually shortens, the thickness of the 3D porous copper foil current collector gradually decreases. After rolling to an appropriate thickness, a flexible and uniformly thick 3D porous copper foil current collector electrode sheet can be obtained.

[0101] Based on the above electrode sheet, perform electrochemical performance tests: measure the length and width of the electrode sheet after rolling, calculate the mass of the 3D porous copper film per square centimeter, and cut the electrode sheet into a square with a side length of 1 cm. Treat the experimental materials and tools used in the experimental process, such as tweezers, rubber gloves, electrode materials, etc. in a vacuum drying oven, complete the assembly and encapsulation of the battery in a glove box, and perform a cycle life test after the battery has been placed for 24 h.

[0102] Example 2

[0103] This example provides a method for preparing a 3D porous copper foil current collector electrode sheet. The difference between this example and Example 1 is that the mass ratios of graphite, carbon black and polyvinylidene fluoride are 66.67%, 25.00% and 8.33% respectively.

[0104] Example 3

[0105] This example provides a method for preparing a 3D porous copper foil current collector electrode sheet. The difference between this example and Example 1 is that the mass ratios of graphite, carbon black and polyvinylidene fluoride are 63.64%, 27.27% and 9.09% respectively.

[0106] Example 4

[0107] This example provides a method for preparing a 3D porous copper foil current collector electrode sheet. The difference between this example and Example 1 is that the mass ratios of graphite, carbon black, and polyvinylidene fluoride are 60.00%, 30.00%, and 10.00% respectively.

[0108] Example 5

[0109] This example provides a method for preparing a 3D porous copper foil current collector electrode sheet. The difference between this example and Example 1 is that the mass ratios of graphite, carbon black, and polyvinylidene fluoride are 75.00%, 18.75%, and 6.25% respectively.

[0110] Comparative Example 1

[0111] The difference between Comparative Example 1 and Example 1 is that during the reduction process of solid-phase sintering the 3D porous copper film, hydrogen was not introduced and heat was not kept. Take Comparative Example 1 with an area of 1 cm 2 and Examples 1 to 5 for cycle life tests. The test results are shown in Table 2.

[0112] As can be seen from Table 2, for Examples 1 to 5, different graphite ratios will lead to differences in cycle life: when the graphite ratio decreases, the wettability of the electrolyte decreases, resulting in a reduction in the contact area between the electrode and the electrolyte, thus leading to a decrease in the battery cycle life; however, when the graphite ratio exceeds 75.00%, the pores originally present in the electrode sheet are filled, resulting in a decrease in porosity, then the wettability of the electrolyte decreases, and the contact area between the electrode and the electrolyte also decreases accordingly, thus leading to a decrease rather than an increase in the battery cycle life.

[0113] It can also be seen from Table 2 that for Example 1 and Comparative Example 1, if hydrogen is not introduced and heat is not kept during the reduction process of solid-phase sintering the 3D porous copper film, the microstructure of the copper film cannot be improved, resulting in a significant reduction in porosity, a decrease in the wettability of the electrolyte, and thus a decrease in the battery cycle life.

[0114] Table 2 Comparison of cycle and rate performance tests between Examples 1 to 5 and Comparative Examples 1 to 3

[0115] Test Sample Proportion of Graphite / % Proportion of Carbon Black / % Proportion of Polyvinylidene Fluoride / % Cycle Life / times Example 1 69.23 23.08 7.69 6377 Example 2 66.67 25.00 8.33 5931 Example 3 63.64 27.27 9.09 3127 Example 4 60.00 30.00 10.00 2543 Example 5 75.00 18.75 6.25 4138 Comparative Example 1 69.23 23.08 7.69 1209

[0116] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific implementation", or "some implementations" etc. means that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example.

[0117] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A preparation method of a copper foil current collector, characterized in that, The method includes: Providing copper powder; Mixing the copper powder with an N-methylpyrrolidone solvent and polyacrylonitrile (PAN) to obtain a casting solution; Performing film pressing and curing on the casting solution to obtain a green body of a 3D porous copper film; Performing solid-phase sintering on the green body of the 3D porous copper film to obtain a 3D porous copper film; Preparing a nano-active material; Processing the nano-active material and the 3D porous copper film to obtain a copper foil current collector.

2. The preparation method of the copper foil current collector according to claim 1, characterized in that, Mixing the copper powder with an N-methylpyrrolidone solvent and polyacrylonitrile (PAN) to obtain a casting solution, including: Mixing a first preset mass of copper powder with a second preset mass of N-methylpyrrolidone solvent to dissolve the copper powder to form a mixed solution; Stirring and mixing a third preset mass of polyacrylonitrile (PAN) with the mixed solution to form a casting solution.

3. The preparation method of the copper foil current collector according to claim 1, characterized in that, The copper powder, performing film pressing and curing on the casting solution to obtain a green body of a 3D porous copper film, including: Pouring the casting solution onto a flat object and using a film doctor to scrape the casting solution to form a flat film on the flat object; Placing the flat object with the flat film in distilled water for a conversion reaction, and after the conversion reaction ends, drying and pressing the flat film to obtain a green body of a 3D porous copper film.

4. The preparation method of the copper foil current collector according to claim 1, characterized in that, Performing solid-phase sintering on the green body of the 3D porous copper film to obtain a 3D porous copper film, including: Placing the green body of the 3D porous copper film in a furnace, heating it to a first preset temperature at a first preset heating rate and holding for a first duration; Performing a temperature reduction treatment on the furnace. When the temperature in the furnace drops below a second preset temperature, heating it to a second preset temperature at a second preset heating rate and introducing argon; When the temperature in the furnace is within a first temperature range, introducing hydrogen and holding for a second duration; Performing a temperature reduction treatment on the furnace. When the temperature in the furnace drops below a second preset temperature, closing the hydrogen and introducing argon. After the temperature in the furnace drops to room temperature, the 3D porous copper film is obtained.

5. The preparation method of the copper foil current collector according to claim 1, wherein, The preparing the nano-active material, including: Performing ball milling on a graphite raw material to obtain nano-scale graphite; Pouring the nano-scale graphite, carbon black, and polyvinylidene fluoride into an N-methylpyrrolidone solvent and stirring to obtain a nano-active material.

6. The preparation method of the copper foil current collector according to claim 1, characterized in that, Processing the nano-active material and the 3D porous copper film to obtain a copper foil current collector, including: Placing the 3D porous copper film in the nano-active material for ultrasonic treatment to obtain an electrode sheet raw material; Removing the excess nano-active material on the surface of the electrode sheet raw material and drying it in a vacuum drying oven to obtain the 3D porous copper foil current collector.

7. A copper foil current collector, characterized in that, The copper foil current collector is prepared by the method according to any one of claims 1 to 6. Among them, active substances are distributed on the surface of the copper foil current collector; the interior of the copper foil current collector is a 3D porous structure, and the 3D porous structure is filled with active substances.

8. The copper foil current collector according to claim 7, characterized in that The aperture of the pores is 3 μm to 10 μm.

9. The copper foil current collector according to claim 7, characterized in that, The active substance is the nano-active material, and the carbon element content of the nano-active material is more than 98%.

10. An electrode sheet, characterized in that, Including: The copper foil current collector according to claim 7, and the copper foil current collector is a copper foil current collector with a preset thickness.

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