Porous copper foil and preparation method and application thereof

Abstract

The invention relates to a porous copper foil and a preparation method and application thereof, and the method comprises the following steps: a plurality of cathode insulation regions are arranged on a cathode roller, and the total area of the plurality of cathode insulation regions accounts for 5%-50% of the area of a target region on the cathode roller; a plurality of anode insulation regions are arranged on the anode, and the proportion of the absolute value of the difference value between the total area of the anode insulation regions and the total area of the cathode insulation regions in the area of the target region is smaller than or equal to 5%; and the cathode roller and the anode are placed in a copper-containing electrolyte for copper foil electroplating deposition, and the porous copper foil is prepared. According to the method, through cooperation and synergistic interaction of the specific cathode roller and the specific anode roller, the mechanical thickness uniformity of the porous copper foil on the whole surface is improved in the electrodeposition foil generation process, stress concentration is reduced, and then the mechanical performance and the electrical performance of the porous copper foil are improved.

Description

Technical Field

[0001] This application relates to the field of electrolytic copper foil technology, and in particular to porous copper foil, its preparation method and application. Background Technology

[0002] Porous copper foil, as a novel current collector material for lithium batteries, has become a research hotspot for next-generation high-energy-density batteries due to its three-dimensional interconnected structure and larger specific surface area, which can improve the adhesion of negative electrode active materials and alleviate volume expansion during charging and discharging. Currently, the main methods for preparing porous copper foil include chemical etching, electrochemical deposition, laser processing, and dealloying, all of which suffer from uneven thickness in the resulting porous copper foil. Summary of the Invention

[0003] Therefore, it is necessary to provide a porous copper foil that can improve the thickness uniformity of porous copper foil, as well as its preparation method and application.

[0004] One aspect of this application provides a method for preparing porous copper foil, comprising the following steps:

[0005] Multiple cathode insulating areas are provided on the cathode roller, wherein the total area of ​​the multiple cathode insulating areas accounts for 5% to 50% of the area of ​​the region where the multiple cathode insulating areas are located;

[0006] Multiple anode insulating regions are provided on the anode, wherein the absolute value of the difference between the total area of ​​the multiple anode insulating regions and the total area of ​​the multiple cathode insulating regions accounts for less than or equal to 5% of the area of ​​the region where the multiple cathode insulating regions are located.

[0007] The cathode roller and the anode are placed in a copper-containing electrolyte for electroplating to deposit copper foil, thereby obtaining the porous copper foil.

[0008] The above method forms a defined area of ​​electrical shielding by setting multiple cathode insulating regions on the cathode roller and controlling the total area of ​​these regions to be 5% to 50% of the area of ​​the target region (hereinafter referred to as the "target area"). The cathode insulating regions correspond to the porous regions of the porous copper foil, thereby precisely and efficiently shielding the electrodeposition process and directly producing porous copper foil with a predetermined pattern. At the same time, by setting multiple anode insulating regions of a defined area on the anode, it helps to balance the electric field and current density distribution, overcome the current distortion caused by the cathode insulating regions, and improve the uniformity of copper deposition. Moreover, controlling the deviation between the total area of ​​the multiple anode insulating regions and the total area of ​​the multiple cathode insulating regions within 5% can further improve the uniformity of copper deposition. The above method, through the cooperation of specific cathode rollers and specific anode rollers, synergistically enhances the mechanical thickness uniformity of the porous copper foil across the entire surface during the electrodeposition process, reduces stress concentration, and thus improves the mechanical and electrical properties of the porous copper foil.

[0009] The above method controls the thickness difference between the porous region and the copper foil region of the porous copper foil to within 10%, achieving a breakthrough in the thickness uniformity of the porous copper foil. When porous copper foil with good thickness uniformity is used as the negative electrode current collector material of lithium-ion batteries, it can improve the current distribution uniformity and thus improve the cycle stability of lithium-ion batteries.

[0010] In some embodiments, the cathode roller includes a first deposition region, a second deposition region, and a third deposition region distributed along the axial direction of the cathode roller, wherein the first deposition region and the third deposition region are not provided with cathode insulating regions, and the plurality of cathode insulating regions are provided in the second deposition region.

[0011] In some embodiments, the distribution width of the plurality of cathode insulating regions along the axial direction of the cathode roller is equal to the distribution width of the plurality of anode insulating regions along the axial direction of the anode roller.

[0012] In some of these implementations, at least one of the following conditions is satisfied:

[0013] (1) The total area of ​​the plurality of cathode insulating regions is equal to the total area of ​​the plurality of anode insulating regions;

[0014] (2) The plurality of cathode insulating regions are arranged at equal intervals, and the minimum distance between two adjacent cathode insulating regions is 12.5µm~3000µm;

[0015] (3) The cathode insulating region is circular, and the maximum diameter of the cathode insulating region is 50µm~1000µm;

[0016] (4) The plurality of anode insulation regions are arranged at equal intervals, and the minimum distance between two adjacent anode insulation regions is 45mm~55mm;

[0017] (5) The anode insulation area is elongated.

[0018] In some embodiments, the thickness of the cathode insulating region is greater than or equal to the thickness of the porous copper foil;

[0019] Optionally, the thickness of the cathode insulating region is 50 μm to 500 μm.

[0020] In some embodiments, the material of the cathode insulating region or the anode insulating region, by mass percentage, comprises the following raw material components: 40% to 60% acrylate, 30% to 50% solvent, 1% to 3% active monomer, 0.01% to 0.05% stabilizer, and 0.01% to 0.1% photoinitiator.

[0021] In some embodiments, the copper-containing electrolyte contains copper ions at a mass concentration of 70 g / L to 130 g / L, sulfuric acid at a mass concentration of 80 g / L to 130 g / L, chloride ions at a mass concentration of 10 mg / L to 50 mg / L, brightener at a mass concentration of 1 mg / L to 50 mg / L, inhibitor at a mass concentration of 1 mg / L to 50 mg / L, and leveling agent at a mass concentration of 0.1 mg / L to 50 mg / L.

[0022] Optionally, the brightener includes one or more of 3-mercaptobenzimidazole, sodium polydithiopropane sulfonate, sodium isothiourea propane sulfonate, sodium 3-thiopropane sulfonate, and sodium formamide propane sulfonate.

[0023] Optionally, the inhibitor includes one or more of polyethylene glycol, polypropylene glycol, polyether, and hydroxyethyl cellulose;

[0024] Optionally, the leveling agent includes one or more of collagen, gelatin, polyethyleneimine, benzotriazole, and tetrahydrothiazolidinone.

[0025] In some of these implementations, at least one of the following conditions is satisfied:

[0026] (1) The temperature of the copper-containing electrolyte is 40℃~70℃;

[0027] (2) The current density of the electroplating is 25 A / dm. 2 ~50A / dm 2 ;

[0028] (3) The rotational speed of the cathode roller is 2m / min to 15m / min.

[0029] A second aspect of this application provides a porous copper foil comprising adjacent porous regions and dense regions, wherein the total area of ​​through-holes in the porous regions accounts for 5% to 50% of the area of ​​the porous regions, and the ratio of the difference between the average thickness of the porous regions and the average thickness of the dense regions to the average thickness of the porous regions is less than or equal to 10%; or,

[0030] The porous copper foil was prepared using the method described in the first aspect.

[0031] With the total area of ​​through holes accounting for 5% to 50%, the above-mentioned porous copper foil achieves a ratio of less than or equal to 10% between the average thickness of the porous region and the average thickness of the dense region and the average thickness of the porous region. This significantly improves the thickness uniformity of the porous copper foil, whereas the thickness difference between the porous region and the dense region of traditional porous copper foil is usually more than 20%.

[0032] When the aforementioned porous copper foil is used as a negative electrode current collector, a higher proportion of active material can be coated, increasing the energy density of the battery; it can provide more space for volume expansion, reduce the expansion ratio of the cell structure, stabilize the mechanical structure of the cell, and reduce the probability of damage to the battery and battery pack; the aforementioned porous copper foil has a uniform thickness, which can suppress the formation of lithium dendrites during the cycle charging and discharging process, reduce the risk of short circuit and thermal runaway, and enhance the safety of the battery.

[0033] In some embodiments, the porous copper foil satisfies at least one of the following conditions:

[0034] (1) The average thickness of the porous copper foil is 4μm~18μm;

[0035] (2) The absolute value of the difference between the percentage of the total area of ​​the porous region to the area of ​​the porous region and the weight reduction rate of the porous region is ≤5%;

[0036] (3) The through holes in the porous region are circular, and the diameter of the through holes is 50µm~1000µm;

[0037] (4) The longitudinal tensile strength of the porous region is 200MPa~600MPa;

[0038] (5) The transverse tensile strength of the porous region is 100MPa~500MPa;

[0039] (6) The longitudinal fracture elongation of the porous region is ≥0.6%;

[0040] (7) The transverse fracture elongation of the porous region is ≥0.4%.

[0041] A third aspect of this application provides a negative electrode current collector comprising a porous copper foil prepared by the preparation method described in the first aspect, or comprising a porous copper foil as described in the second aspect.

[0042] A fourth aspect of this application provides a lithium-ion battery including the negative electrode current collector described in the third aspect. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the cathode insulation area on the cathode roller surface in Example 1.

[0044] Figure 2 This is a schematic diagram of the anode insulation area on the surface of the anode roller in Example 1.

[0045] Figure 3 This is a SEM image of the porous copper foil prepared in Example 1.

[0046] Explanation of reference numerals in the attached drawings: 1. First sedimentation zone; 2. Second sedimentation zone; 3. Third sedimentation zone; 4. Cathode insulation zone; 5. Anode insulation zone. Detailed Implementation

[0047] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0049] To make the objectives, technical solutions, and advantages of this application clearer and more concise, the following specific embodiments are used for illustration, but this application is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of this application and can be used to describe this application, but should not be construed as limiting the scope of this application. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

[0050] When porous copper foil is used as a current collector material in batteries, its through-pore structure can improve electrolyte wettability, shorten ion transport paths, and enable batteries to have better rate performance. It can also effectively buffer volume expansion during charge and discharge, increasing the cycle life of silicon anodes to more than 500 cycles with a capacity retention of 85%. In addition, the porous structure of porous copper foil can reduce interfacial impedance and bond more tightly with metals, making it a more ideal current collector material for battery anodes. The main methods for preparing porous copper foil include chemical etching, electrochemical deposition, laser processing, and dealloying. Among them, chemical etching uses mask-assisted chemical etching technology, which uses photoresist to pattern and protect non-porous areas, and uses acidic etching solution to selectively etch the copper foil to form a porous structure. However, it suffers from uneven thickness due to over-etching at the edges. Electrochemical shielding deposition uses porous shielding materials to template and guide copper deposition. Although it can precisely control the pore size distribution, the template shape will cause a significant increase in the thickness of the copper foil. Laser processing uses femtosecond lasers to prepare micro-pore arrays on the surface of copper foil. The processing accuracy can reach the micrometer level, but the heat-affected zone will cause the material around the pores to thicken, and the cost is too high to mass-produce. Dealloying uses a dealloying process that selectively dissolves copper-aluminum alloys to prepare nanoscale porous structures. However, the porous copper foil produced has a large thickness gradient from the edge to the center. At present, the porous copper foils prepared by the above methods all have the problem of uneven thickness.

[0051] Based on this, one embodiment of this application provides a method for preparing porous copper foil, comprising the following steps:

[0052] Multiple cathode insulation zones are set on the cathode roller, wherein the total area of ​​the multiple cathode insulation zones accounts for 5% to 50% of the area of ​​the region where the multiple cathode insulation zones are located;

[0053] Multiple anode insulation regions are set on the anode, wherein the absolute value of the difference between the total area of ​​the multiple anode insulation regions and the total area of ​​the multiple cathode insulation regions accounts for less than or equal to 5% of the area of ​​the region where the multiple cathode insulation regions are located.

[0054] A porous copper foil is produced by electroplating copper foil by placing the cathode roller and anode in a copper-containing electrolyte.

[0055] The above method forms a defined area of ​​electrical shielding by setting multiple cathode insulating regions on the cathode roller and controlling the total area of ​​these regions to be 5% to 50% of the area of ​​the target region (hereinafter referred to as the "target area"). The cathode insulating regions correspond to the porous regions of the porous copper foil, thereby precisely and efficiently shielding the electrodeposition process and directly producing porous copper foil with a predetermined pattern. At the same time, by setting multiple anode insulating regions of a defined area on the anode, it helps to balance the electric field and current density distribution, overcome the current distortion caused by the cathode insulating regions, and improve the uniformity of copper deposition. Moreover, controlling the deviation between the total area of ​​the multiple anode insulating regions and the total area of ​​the multiple cathode insulating regions within 5% can further improve the uniformity of copper deposition. The above method, through the cooperation of specific cathode rollers and specific anodes, synergistically enhances the mechanical thickness uniformity of the porous copper foil across the entire surface during the electrodeposition process, reduces stress concentration, and thus improves the mechanical and electrical properties of the porous copper foil.

[0056] The above method controls the thickness difference between the porous region and the copper foil region of the porous copper foil to within 10%, achieving a breakthrough in the thickness uniformity of the porous copper foil. When porous copper foil with good thickness uniformity is used as the negative electrode current collector material of lithium-ion batteries, it can improve the current distribution uniformity and thus improve the cycle stability of lithium-ion batteries.

[0057] Understandably, the deviation between the total area of ​​multiple anode insulation regions and the total area of ​​multiple cathode insulation regions is controlled within 0 to 5%. When the deviation is 0, the total area of ​​multiple cathode insulation regions is equal to the total area of ​​multiple anode insulation regions.

[0058] Understandably, "the area of ​​the region containing multiple cathode insulating areas" means: the target area, which is equal to the maximum width * maximum length of the array formed by all cathode insulating areas on the cathode roller surface. As an example, Figure 1 The area of ​​the target region is a * the circumference of the cathode roller.

[0059] Understandably, the shape formed by the arrangement of the cathode insulating regions corresponds to the shape of the pores in the porous copper foil to be deposited.

[0060] As an example, the total area of ​​multiple cathode insulation zones can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50% of the target area on the cathode roller surface, or it can be within the range formed by any two of the above point values ​​as end values.

[0061] Furthermore, the total area of ​​the multiple cathode insulating regions is 10% to 40% of the target area on the cathode roller surface. Within this range, the electrical properties and mechanical strength of the porous copper foil can be better balanced.

[0062] As an example, the absolute value of the difference between the total area of ​​multiple anode insulation regions and the total area of ​​multiple cathode insulation regions can be controlled as a percentage of the target area of ​​0%, 1%, 2%, 3%, 4%, and 5%, or it can be within the range formed by any two of the above point values ​​as endpoints.

[0063] In some embodiments, the total area of ​​multiple cathode insulating regions is equal to the total area of ​​multiple anode insulating regions. This means the cathode shielding area is equal to the anode shielding area. This arrangement improves the symmetry of the electric field distribution within the electrolytic cell, ensuring that the insulating regions of the cathode and anode have similar shielding effects on the current lines, reducing local electric field distortion, and making the current density deposited more uniformly on the cathode roller surface. This improves the uniformity of the copper foil deposition thickness, avoiding edge over-etching or excessive center thickness. It also makes the actual effective conductive area of ​​the anode more consistent with the effective deposition area of ​​the cathode, which is beneficial for stabilizing the deposition process and reducing thickness fluctuations in the porous copper foil. Furthermore, the equality of the cathode shielding area and the anode shielding area also improves the accuracy of the through-hole diameter in the porous copper foil, reducing peri-hole thickening caused by over-deposition, and further reducing the thickness difference between the porous and dense regions on the porous copper foil.

[0064] In some embodiments, a plurality of cathode insulating regions are arranged circumferentially around the cathode roller, and a plurality of anode insulating regions are arranged circumferentially along the anode roller. The distribution areas of the plurality of anode insulating regions on the anode roller are at least partially opposite to the distribution areas of the plurality of cathode insulating regions on the cathode roller. The anode roller may be assembled from anode plates.

[0065] Understandably, the at least partially opposite arrangement of the multiple anode insulating regions in the distribution area of ​​the anode roller and the at least partially opposite arrangement of the multiple cathode insulating regions in the distribution area of ​​the cathode roller is because the anode roller may have only half of the roller surface.

[0066] In some of these implementations, please refer to Figure 1The cathode roller includes a first deposition zone 1, a second deposition zone 2 and a third deposition zone 3 distributed along the axial direction of the cathode roller. The first deposition zone 1 and the third deposition zone 3 are not provided with cathode insulation zones, and multiple cathode insulation zones 4 are provided in the second deposition zone 2.

[0067] In some of these implementations, please refer to Figure 2 Similar to the cathode roller, the anode groove also has multiple anode insulation zones 5 in the middle area.

[0068] In some of these implementations, please refer to Figure 1 and Figure 2 The distribution width 'a' of multiple cathode insulating regions 4 along the axial direction of the cathode roller is equal to the distribution width 'b' of multiple anode insulating regions 5 along the axial direction of the anode roller. This arrangement allows the cathode insulating regions and anode insulating regions to achieve a high degree of symmetrical matching. When the current lines pass through the electrolyte between the cathode and anode, they will more evenly bypass the insulating regions, avoiding excessively high or low local current densities. This reduces edge effects or distortions in the electric field, further improving the thickness uniformity of the porous copper foil.

[0069] Understandably, the distribution width 'a' of multiple cathode insulating areas along the axial direction of the cathode roller refers to the distance between the outermost edges of the multiple cathode insulating areas along the axial direction of the cathode roller, and is the width occupied by the multiple cathode insulating areas as a whole along the axial direction of the cathode roller. Similarly, the distribution width 'b' of multiple anode insulating areas along the axial direction of the anode roller refers to the distance between the outermost edges of the multiple anode insulating areas along the axial direction of the anode roller, and is the width occupied by the multiple anode insulating areas as a whole along the axial direction of the anode roller.

[0070] In some embodiments, multiple cathode insulating regions are arranged at equal intervals, with the minimum distance between two adjacent cathode insulating regions being 12.5µm to 3000µm.

[0071] In some embodiments, the cathode insulation region is circular or elliptical.

[0072] In some embodiments, the cathode insulating region is circular, and the maximum diameter of the cathode insulating region is 50µm to 1000µm.

[0073] As an example, the maximum diameter of the cathode insulation region can be 50µm, 100µm, 200µm, 300µm, 400µm, 500µm, 600µm, 700µm, 800µm, 900µm and 1000µm, or it can be within the range formed by any two of the above point values ​​as end values.

[0074] Furthermore, the maximum diameter of the cathode insulation region is 100µm to 800µm. Within this maximum diameter range, the overall performance of the porous copper foil is improved, with better thickness uniformity, mechanical strength, and electrical properties.

[0075] In some embodiments, multiple anode insulation regions are arranged at equal intervals, with the minimum distance between two adjacent anode insulation regions being 45mm to 55mm.

[0076] Furthermore, the minimum spacing between two adjacent anode insulation zones is 50 mm.

[0077] In some embodiments, the anode insulation region is elongated.

[0078] In some embodiments, the thickness of the cathode insulating region is greater than or equal to the thickness of the porous copper foil.

[0079] Furthermore, the thickness of the cathode insulation region is 50μm~500μm.

[0080] In some embodiments, the material of the cathode insulating region or the anode insulating region, by mass percentage, comprises the following raw material components: 40% to 60% acrylate, 30% to 50% solvent, 1% to 3% active monomer, 0.01% to 0.05% stabilizer, and 0.01% to 0.1% photoinitiator.

[0081] Furthermore, solvents include lipid solvents, such as isopropyl acrylate.

[0082] Furthermore, the active monomers include nano-solid particles, such as nano-silica.

[0083] Furthermore, stabilizers include ketone antioxidants, such as methyl ketone.

[0084] Furthermore, photoinitiators include ether compounds, such as methyl ether.

[0085] Understandably, the material of the aforementioned cathode insulation area or anode insulation area is an electrically insulating and corrosion-resistant material. The electrically insulating and corrosion-resistant material is sprayed onto the surface of the cathode roller and cured to form an insulating layer in the cathode insulation area; the electrically insulating and corrosion-resistant material is sprayed onto the anode plate and cured to form an insulating layer in the anode insulation area.

[0086] In some embodiments, the copper electrolyte contains copper ions at a mass concentration of 70 g / L to 130 g / L, sulfuric acid at a mass concentration of 80 g / L to 130 g / L, and chloride ions at a mass concentration of 10 mg / L to 50 mg / L.

[0087] In some embodiments, the copper electrolyte contains copper ions at a mass concentration of 70 g / L to 130 g / L, sulfuric acid at a mass concentration of 80 g / L to 130 g / L, chloride ions at a mass concentration of 10 mg / L to 50 mg / L, brightener at a mass concentration of 1 mg / L to 50 mg / L, inhibitor at a mass concentration of 1 mg / L to 50 mg / L, and leveling agent at a mass concentration of 0.1 mg / L to 50 mg / L.

[0088] In some embodiments, the brightener includes one or more of 3-mercaptobenzimidazole, sodium polydithiopropane sulfonate, sodium isothiourea propane sulfonate, sodium 3-thiopropane sulfonate, and sodium formamide propane sulfonate.

[0089] In some embodiments, the inhibitor includes one or more of polyethylene glycol, polypropylene glycol, polyether, and hydroxyethyl cellulose;

[0090] In some embodiments, the leveling agent includes one or more of collagen, gelatin, polyethyleneimine, benzotriazole, and tetrahydrothiazolidinone.

[0091] In some embodiments, the temperature of the copper-containing electrolyte is 40°C to 70°C.

[0092] In some embodiments, the current density for electroplating is 10 A / dm² to 100 A / dm².

[0093] As an example, the current density for electroplating is 10A / dm², 15A / dm², 20A / dm², 25A / dm², 30A / dm², 35A / dm², 40A / dm², 45A / dm², 50A / dm², 55A / dm², 60A / dm², 65A / dm², 70A / dm², 75A / dm², 80A / dm², 85A / dm², 90A / dm², 95A / dm², and 100A / dm², or any two of the above values ​​can be used as endpoints within the range.

[0094] Furthermore, the electroplating current density is 25 A / dm². 2 ~50A / dm 2 Within this current density range, the deposition rate can be optimized, reducing the looseness of the porous copper foil structure and dendrite growth, improving the morphology and uniformity of the porous copper foil through-hole structure, forming a through-hole structure with clear edges and consistent pore size, thereby further enhancing the performance of the porous copper foil.

[0095] In some embodiments, the rotational speed of the cathode roller is 2 m / min to 15 m / min.

[0096] In some embodiments, the anode plate is assembled into the electrolytic cell, the cathode roller is adjusted to the matching position of the anode assembly, and the copper-containing electrolyte is conveyed at a controllable flow rate. Under a certain temperature and current density, the cathode roller is kept running at a uniform speed so that copper ions in the electrolyte are uniformly deposited on the surface of the cathode roller through electrochemical action.

[0097] Understandably, adjusting the cathode roller to the anode assembly fit position means that the cathode roller is embedded in the anode groove, and the two insulating areas are in a face-to-face position, such as being in the exact middle position of the cathode roller and the anode groove.

[0098] In some embodiments, the copper layer deposited on the cathode roller surface is passivated with chromium anhydride passivation solution, and then successively undergoes edge trimming, winding, baking and slitting processes to finally obtain the finished porous copper foil.

[0099] A second aspect of this application provides a porous copper foil, comprising adjacent porous regions and dense regions, wherein the total area of ​​through-holes in the porous regions accounts for 5% to 50% of the area of ​​the porous regions, and the ratio of the difference between the average thickness of the porous regions and the average thickness of the dense regions to the average thickness of the porous regions is less than or equal to 10%; or,

[0100] The porous copper foil was prepared using the method described in the first aspect.

[0101] Understandably, the porous area refers to the maximum width multiplied by the maximum length of the array formed by all through-holes on the copper foil.

[0102] As an example, the total area of ​​the through holes in the porous region can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50% of the total area of ​​the porous region, or it can be within the range formed by any two of the above point values ​​as end values.

[0103] Furthermore, the total area of ​​through holes in the porous region can account for 10% to 40% of the total area of ​​the porous region.

[0104] As an example, the ratio of the difference between the average thickness of the porous region and the average thickness of the dense region to the average thickness of the porous region can be 0, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%, or any two of the above values ​​can be used as endpoints within the range. A smaller ratio of the difference between the average thickness of the porous region and the average thickness of the dense region to the average thickness of the porous region is better, as a smaller ratio indicates better thickness uniformity of the porous copper foil.

[0105] In some embodiments, dense regions are provided on both sides of the porous region.

[0106] Understandably, dense regions of porous copper foil are formed in the first and third deposition zones on the cathode roller, and porous regions of porous copper foil are formed in the second deposition zone.

[0107] In some embodiments, the through holes in the porous region are evenly spaced.

[0108] Furthermore, the through holes in the porous region are arranged at equal intervals both horizontally and vertically, forming an array. Understandably, after the copper foil is flattened, the through holes on it are arranged in a rectangular array.

[0109] In some embodiments, the average thickness of the porous copper foil is 4 μm to 18 μm.

[0110] As an example, the average thickness of the porous copper foil can be 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm and 18μm, or it can be within the range formed by any two of the above point values ​​as end values.

[0111] Furthermore, the average thickness of the porous copper foil is 6 μm to 12 μm.

[0112] In some of these embodiments, the porous copper foil is 10% to 50% lighter than the conventional dense lithium-ion battery copper foil of the same thickness.

[0113] In some embodiments, the absolute value of the difference between the percentage of the total area of ​​through holes in the porous region to the total area of ​​the porous region and the weight reduction rate of the porous region is ≤5%. Controlling the deviation between the weight reduction rate of the porous region and the percentage of the total area of ​​through holes within 5% can further improve the mechanical properties of porous copper foil.

[0114] In some embodiments, the through holes in the porous region are circular or elliptical.

[0115] In some embodiments, the through holes in the porous region are circular, and the diameter of the through holes is 50µm to 1000µm.

[0116] In some embodiments, the longitudinal tensile strength of the porous region is 200 MPa to 600 MPa.

[0117] In some embodiments, the transverse tensile strength of the porous region is 100MPa to 500MPa.

[0118] In some embodiments, the longitudinal elongation at break of the porous region is ≥0.6%.

[0119] In some embodiments, the transverse fracture elongation of the porous region is ≥0.4%.

[0120] A third aspect of this application provides a negative electrode current collector comprising a porous copper foil prepared by the method of the first aspect, or a porous copper foil comprising the method of the second aspect.

[0121] In some embodiments, the tab connection point of the negative electrode current collector is located in the dense region of the porous copper foil. When the aforementioned porous copper foil serves as the current collector material for lithium batteries, its porous and dense regions can balance the electrochemical performance and mechanical strength of the battery. The dense region, as the tab connection point, improves process reliability and current distribution uniformity. The porous structure of the porous region enhances electrolyte wettability, promotes rapid lithium-ion transport, reduces weight, and improves the adhesion of active materials, thereby optimizing the battery's rate performance and energy density. The dense region provides necessary mechanical support, ensuring the structural integrity of the porous copper foil during battery assembly and charge / discharge processes. More importantly, the dense region, as the tab connection point, can withstand the mechanical stress during welding due to its dense structure, avoiding breakage or poor contact caused by insufficient strength in the porous area. The tab located in the dense region has higher conductivity, and the welding process has better compatibility with dense materials, preventing short-circuit risks caused by burrs or cracks. The aforementioned design balances material lightweighting and process reliability, promoting efficient and safe operation of lithium battery current collectors.

[0122] A fourth aspect of this application provides a lithium-ion battery, including the negative electrode current collector of the third aspect.

[0123] The porous region of the porous copper foil optimizes the electrochemical performance of the material, while the dense region solves the problems of mechanical strength and tab connection, thus improving the performance of lithium batteries while taking into account manufacturing feasibility and long-term reliability.

[0124] To better illustrate this application, the following description, in conjunction with specific embodiments, further explains its content. The following are specific embodiments.

[0125] In the following examples, the acid refers to sulfuric acid.

[0126] Example 1

[0127] The preparation method of porous copper foil includes the following steps:

[0128] Setting up a cathode insulation zone: A spray device is installed directly above the cathode roller. The cathode roller is made of titanium. This spray device is controlled by a drive motor, and an electromagnetic control valve is installed in the pipeline. The end of the pipeline is connected to a raw material storage tank. Electrically insulating and corrosion-resistant material is poured into the storage tank, activating the drive system to rotate the cathode roller, and simultaneously opening the electromagnetic valve. Figure 1As shown, an electrically insulating and corrosion-resistant material is precisely sprayed onto the surface of a titanium roller according to a predetermined pattern and distribution rule, forming regularly distributed shielding points composed of an electrically insulating layer, i.e., forming multiple cathode insulating areas. The thickness of the cathode insulating area is 100μm, the diameter of the cathode insulating area is controlled at 1000µm, the distribution width 'a' of the multiple cathode insulating areas along the axial direction of the cathode roller is controlled at 300mm, and the total area of ​​the multiple cathode insulating areas is 10% of the target area area on the cathode roller. After completing the complete circumferential spraying, the system operation is stopped to allow the coating to cure. The components of the electrically insulating and corrosion-resistant material, by mass percentage, include 55% acrylate, 42.9% solvent (isopropyl acrylate), 2% active monomer (nano silica particles), 0.05% stabilizer (methyl ketone), and 0.05% photoinitiator (methyl ether).

[0129] Set up an anode insulation area: such as Figure 2 As shown, an electrical insulating layer of a defined area is coated on a predetermined area on the surface of the anode plate to form multiple anode insulating areas. The total area of ​​the multiple anode insulating areas is 10% of the target area. The multiple anode insulating areas are evenly arranged at equal intervals, and the distribution width b of the multiple anode insulating areas along the axial direction of the anode roller is equal to the distribution width a of the multiple cathode insulating areas along the axial direction of the cathode roller.

[0130] Electrolytic deposition of porous copper foil: The anode plate is assembled into the electrolytic cell, the cathode roller is adjusted to the appropriate position of the anode assembly, and high-purity copper sulfate electrolyte is delivered at a fixed flow rate through the bottom liquid supply system. The electrolyte temperature is 55℃, the current density is 30A / dm², and the mass concentration of copper ions in the electrolyte is 90g / L, the mass concentration of acid is 110g / L, the mass concentration of chloride ions is 29mg / L, the mass concentration of sodium polydithiopropane sulfonate is 20mg / L, the mass concentration of sodium 3-thiopropane sulfonate is 5mg / L, the mass concentration of sodium isothiourea propane sulfonate is 5mg / L, the mass concentration of tetrahydrothiazolylthione is 6mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) is 6mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) is 2mg / L. The cathode roller is kept running at a constant speed so that copper ions in the electrolyte are uniformly deposited on the roller surface through electrochemical action. After passivation treatment with chromium anhydride passivation solution, and then through processes such as edge trimming, winding, baking, and slitting, a finished porous copper foil with an average thickness of 6µm is finally obtained.

[0131] Example 2

[0132] Example 2 is basically the same as Example 1, except that:

[0133] When setting up the cathode insulation area, the total area of ​​multiple cathode insulation areas on the cathode roller is controlled to be 20% of the target area on the cathode roller;

[0134] When setting up the anode insulation zone, the total area of ​​multiple anode insulation zones should be controlled to be 20% of the target area area;

[0135] During the electrolytic deposition of porous copper foil, the electrolyte temperature was 50℃, the current density was 40A / dm², and the mass concentration of copper ions in the electrolyte was 90g / L, the mass concentration of acid was 110g / L, the mass concentration of chloride ions was 25mg / L, the mass concentration of sodium 3-thiopropanesulfonate was 26mg / L, the mass concentration of sodium formamide propanesulfonate was 5mg / L, the mass concentration of tetrahydrothiazole-2-thione was 6mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) was 6mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) was 4mg / L.

[0136] A porous copper foil with an average thickness of 8µm was obtained.

[0137] Example 3

[0138] Example 3 is basically the same as Example 1, except that:

[0139] When setting up the cathode insulation area, the total area of ​​multiple cathode insulation areas on the cathode roller is controlled to be 30% of the target area on the cathode roller;

[0140] When setting up the anode insulation zone, the total area of ​​multiple anode insulation zones should be controlled to be 30% of the target area area;

[0141] During the electrolytic deposition of porous copper foil, the electrolyte temperature was 45℃, the current density was 45A / dm², and the mass concentration of copper ions in the electrolyte was 85g / L, the mass concentration of acid was 100g / L, the mass concentration of chloride ions was 28mg / L, the mass concentration of sodium 3-thiopropanesulfonate was 29mg / L, the mass concentration of sodium isothiourea propanesulfonate was 5mg / L, the mass concentration of tetrahydrothiazolium-2-thione was 7mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) was 5mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) was 0.5mg / L.

[0142] A porous copper foil with an average thickness of 6µm was obtained.

[0143] Example 4

[0144] Example 4 is basically the same as Example 1, except that:

[0145] When setting up the cathode insulation area, the total area of ​​multiple cathode insulation areas on the cathode roller is controlled to be 40% of the target area on the cathode roller;

[0146] When setting up the anode insulation zone, the total area of ​​multiple anode insulation zones should be controlled to be 40% of the target area area;

[0147] During the electrolytic deposition of porous copper foil, the electrolyte temperature was 50℃, the current density was 38A / dm², and the mass concentration of copper ions in the electrolyte was 95g / L, the mass concentration of acid was 108g / L, the mass concentration of chloride ions was 32mg / L, the mass concentration of sodium polydithiopropane sulfonate was 30mg / L, the mass concentration of 2-mercaptobenzimidazole was 6mg / L, the mass concentration of tetrahydrothiazolium-2-thione was 8mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) was 4mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) was 5mg / L.

[0148] A porous copper foil with an average thickness of 8µm was obtained.

[0149] Example 5

[0150] Example 5 is basically the same as Example 1, except that:

[0151] When setting up the cathode insulation area, the total area of ​​multiple cathode insulation areas on the cathode roller is controlled to be 50% of the target area on the cathode roller;

[0152] When setting up the anode insulation zone, the total area of ​​multiple anode insulation zones should be controlled to be 50% of the target area area;

[0153] During the electrolytic deposition of porous copper foil, the electrolyte temperature was 50℃, the current density was 36A / dm², and the mass concentration of copper ions in the electrolyte was 100g / L, the mass concentration of acid was 110g / L, the mass concentration of chloride ions was 28mg / L, the mass concentration of sodium isothiourea propanesulfonate was 30mg / L, the mass concentration of 2-mercaptobenzimidazole was 6mg / L, the mass concentration of tetrahydrothiazolium-2-thione was 8mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) was 4mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) was 5mg / L.

[0154] A porous copper foil with an average thickness of 6µm was obtained.

[0155] Example 6

[0156] Example 6 is basically the same as Example 1, except that:

[0157] When setting up the cathode insulation area, the total area of ​​multiple cathode insulation areas on the cathode roller is controlled to be 50% of the target area on the cathode roller;

[0158] When setting up the anode insulation zone, the total area of ​​multiple anode insulation zones should be controlled to be 50% of the target area area;

[0159] During the electrolytic deposition of porous copper foil, the electrolyte temperature was 50℃, the current density was 36A / dm², and the mass concentration of copper ions in the electrolyte was 100g / L, the mass concentration of acid was 110g / L, the mass concentration of chloride ions was 28mg / L, the mass concentration of sodium isothiourea propanesulfonate was 30mg / L, the mass concentration of 2-mercaptobenzimidazole was 6mg / L, the mass concentration of tetrahydrothiazolium-2-thione was 8mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) was 4mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) was 5mg / L.

[0160] A porous copper foil with an average thickness of 10µm was obtained.

[0161] Example 7

[0162] Example 7 is basically the same as Example 1, except that:

[0163] When setting up the cathode insulation area, the total area of ​​multiple cathode insulation areas on the cathode roller is controlled to be 30% of the target area on the cathode roller;

[0164] When setting up the anode insulation zone, the total area of ​​multiple anode insulation zones should be controlled to be 35% of the target area area;

[0165] During the electrolytic deposition of porous copper foil, the electrolyte temperature was 45℃, the current density was 55A / dm², and the mass concentration of copper ions in the electrolyte was 90g / L, the mass concentration of acid was 105g / L, the mass concentration of chloride ions was 29mg / L, the mass concentration of sodium 3-thiopropanesulfonate was 29mg / L, the mass concentration of sodium isothiourea propanesulfonate was 5mg / L, the mass concentration of tetrahydrothiazolium-2-thione was 7mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) was 5mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) was 0.5mg / L.

[0166] A porous copper foil with an average thickness of 6µm was obtained.

[0167] Example 8

[0168] Example 8 is basically the same as Example 1, except that:

[0169] When setting up the cathode insulation area, the total area of ​​multiple cathode insulation areas on the cathode roller is controlled to be 30% of the target area on the cathode roller;

[0170] When setting up the anode insulation zone, the total area of ​​multiple anode insulation zones should be controlled to be 25% of the target area area;

[0171] During the electrolytic deposition of porous copper foil, the electrolyte temperature was 45℃, the current density was 55A / dm², and the mass concentration of copper ions in the electrolyte was 90g / L, the mass concentration of acid was 105g / L, the mass concentration of chloride ions was 29mg / L, the mass concentration of sodium 3-thiopropanesulfonate was 29mg / L, the mass concentration of sodium isothiourea propanesulfonate was 5mg / L, the mass concentration of tetrahydrothiazolium-2-thione was 7mg / L, the mass concentration of polyethylene glycol (molecular weight 6000) was 5mg / L, and the mass concentration of polyethylene glycol (molecular weight 1000) was 0.5mg / L.

[0172] A porous copper foil with an average thickness of 6µm was obtained.

[0173] Example 9

[0174] Example 9 is basically the same as Example 1, except that the thickness of the cathode insulating region is 30 μm.

[0175] Comparative Example 1

[0176] Comparative Example 1 is basically the same as Example 4, except that:

[0177] When setting the cathode insulation area, the total area of ​​the cathode insulation area on the cathode roller should be controlled to be 60% of the target area on the cathode roller.

[0178] When setting up the anode insulation zone, the coverage area of ​​the anode insulation zone should be controlled to be 60% of the target area area;

[0179] A porous copper foil with an average thickness of 6µm was obtained.

[0180] Comparative Example 2

[0181] Comparative Example 2 is basically the same as Example 4, except that:

[0182] When setting the cathode insulation area, the total area of ​​the cathode insulation area on the cathode roller should be controlled to be 60% of the target area on the cathode roller.

[0183] When setting up the anode insulation zone, the coverage area of ​​the anode insulation zone should be controlled to be 60% of the target area area;

[0184] Porous copper foil with an average thickness of 10µm was obtained by adjusting the current density and electroplating time.

[0185] Comparative Example 3

[0186] Comparative Example 3 is basically the same as Example 7, except that:

[0187] When setting the cathode insulation area, the total area of ​​the cathode insulation area on the cathode roller should be controlled to be 30% of the target area on the cathode roller.

[0188] When setting up the anode insulation zone, the coverage area of ​​the anode insulation zone should be controlled to be 40% of the target area.

[0189] Comparative Example 4

[0190] Comparative Example 4 is basically the same as Example 7, except that:

[0191] When setting the cathode insulation area, the total area of ​​the cathode insulation area on the cathode roller should be controlled to be 30% of the target area on the cathode roller.

[0192] When setting up the anode insulation zone, the coverage area of ​​the anode insulation zone should be controlled to be 20% of the target area.

[0193] The porous copper foils prepared in each embodiment and comparative example were subjected to mechanical and electrical property tests, and the test results are shown in Table 1 below.

[0194] Mechanical thickness: measured using a micrometer.

[0195] Areal density: Cut copper foil samples with a length of 100 mm and a width of 100 mm, with a sample area of ​​100 mm². 2 Weigh the sample using a balance. The ratio of the sample weight to the sample area is the surface density.

[0196] The longitudinal tensile strength, transverse tensile strength, longitudinal elongation at break, and transverse elongation at break of the porous region were all measured using a tensile testing machine. Here, longitudinal refers to the direction perpendicular to or along the length (mechanical direction); transverse refers to the direction horizontally or along the width (perpendicular to the mechanical direction).

[0197] Mechanical thickness difference: (Mechanical thickness of porous region - Mechanical thickness of dense region) / Mechanical thickness of dense region.

[0198] Percentage of total through-hole area: refers to the ratio of the total area of ​​through-holes in the porous region to the total area of ​​the porous region.

[0199] Weight reduction rate in porous areas: The percentage reduction in weight of copper foil with porous areas compared to copper foil with non-porous areas of the same area. The test method for weight reduction rate in porous areas is as follows: Cut 100*100mm pieces of foil with porous areas and foil with non-porous areas, weigh them using a balance, and calculate the weight reduction rate as: (Weight of foil with non-porous areas - Weight of foil with porous areas) / Weight of foil with non-porous areas.

[0200] Table 1

[0201]

[0202] As shown in Table 1 above, in Examples 1-9, the total area ratio of through holes in the porous copper foil prepared by the method of this application is controlled between 5% and 50%, and the weight reduction rate of the porous region deviates from the total area ratio of through holes by no more than 5%. This further strictly controls the thickness difference between the porous region and the dense region to within 10%, improving the mechanical thickness uniformity of the porous copper foil, and ensuring that the mechanical properties of the porous copper foil meet the requirements. The porous copper foil prepared in Example 1, as shown... Figure 3 As shown, the porous region has round and uniform pores. When used as a current collector in lithium-ion batteries, the porous region not only allows the negative electrode active material to be more tightly bonded to the current collector, but also reduces the surface density of the porous region by 10.3% compared to the dense region, thereby reducing internal resistance and increasing the energy density of the cell.

[0203] In Comparative Examples 1 and 2, the total area of ​​the cathode insulation region on the cathode roller is 60% of the target area on the cathode roller, which is not in the range of 5% to 50%. The proportion of the total area of ​​the through holes and the weight reduction of the surface density of the porous area are both greater than 50%, resulting in low tensile strength and elongation. In Comparative Examples 3 and 4, the absolute value of the difference between the total area of ​​the anode insulation region and the total area of ​​the cathode insulation region accounts for more than 5% of the target area area. The difference between the weight reduction of the porous area and the proportion of the total area of ​​the through holes is greater than 5%, resulting in a difference of more than 10% between the mechanical thickness of the porous area and the mechanical thickness of the dense area.

[0204] As can be seen from Examples 1 to 6, when the total area of ​​the cathode insulating region is equal to the total area of ​​the anode insulating region, or when the thickness of the cathode insulating region is 50μm to 500μm, the porous copper foil has better thickness uniformity and mechanical properties.

[0205] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0206] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing porous copper foil, characterized in that, Includes the following steps: Multiple cathode insulating areas are provided on the cathode roller, wherein the total area of ​​the multiple cathode insulating areas accounts for 5% to 50% of the area of ​​the region where the multiple cathode insulating areas are located; Multiple anode insulating regions are provided on the anode, wherein the absolute value of the difference between the total area of ​​the multiple anode insulating regions and the total area of ​​the multiple cathode insulating regions accounts for less than or equal to 5% of the area of ​​the region where the multiple cathode insulating regions are located. The cathode roller and the anode are placed in a copper-containing electrolyte for electroplating to deposit copper foil, thereby obtaining the porous copper foil.

2. The method for preparing porous copper foil as described in claim 1, characterized in that, The plurality of cathode insulating regions are arranged around the circumference of the cathode roller, and the plurality of anode insulating regions are arranged along the circumference of the anode roller. The plurality of anode insulating regions are arranged opposite to at least a portion of the distribution area of ​​the anode roller and the plurality of cathode insulating regions are arranged opposite to the distribution area of ​​the cathode roller.

3. The method for preparing porous copper foil as described in claim 1, characterized in that, The cathode roller includes a first deposition area, a second deposition area, and a third deposition area distributed along the axial direction of the cathode roller. The first deposition area and the third deposition area do not have cathode insulating areas, and the plurality of cathode insulating areas are provided in the second deposition area.

4. The method for preparing porous copper foil as described in claim 1, characterized in that, The distribution width of the plurality of cathode insulating regions along the axial direction of the cathode roller is equal to the distribution width of the plurality of anode insulating regions along the axial direction of the anode roller.

5. The method for preparing porous copper foil as described in claim 1, characterized in that, At least one of the following conditions must be met: (1) The total area of ​​the plurality of cathode insulating regions is equal to the total area of ​​the plurality of anode insulating regions; (2) The plurality of cathode insulating regions are arranged at equal intervals, and the minimum distance between two adjacent cathode insulating regions is 12.5µm~3000µm; (3) The cathode insulating region is circular, and the maximum diameter of the cathode insulating region is 50µm~1000µm; (4) The plurality of anode insulation regions are arranged at equal intervals, and the minimum distance between two adjacent anode insulation regions is 45mm~55mm; (5) The anode insulation area is elongated.

6. The method for preparing porous copper foil as described in claim 1, characterized in that, The thickness of the cathode insulating region is greater than or equal to the thickness of the porous copper foil; Optionally, the thickness of the cathode insulating region is 50 μm to 500 μm.

7. The method for preparing porous copper foil according to any one of claims 1 to 6, characterized in that, The material of the cathode insulating region or the anode insulating region, by mass percentage, comprises the following raw material components: 40% to 60% acrylate, 30% to 50% solvent, 1% to 3% active monomer, 0.01% to 0.05% stabilizer, and 0.01% to 0.1% photoinitiator.

8. The method for preparing porous copper foil according to any one of claims 1 to 6, characterized in that, In the copper-containing electrolyte, the mass concentration of copper ions is 70 g / L to 130 g / L, the mass concentration of sulfuric acid is 80 g / L to 130 g / L, the mass concentration of chloride ions is 10 mg / L to 50 mg / L, the mass concentration of brightener is 1 mg / L to 50 mg / L, the mass concentration of inhibitor is 1 mg / L to 50 mg / L, and the mass concentration of leveling agent is 0.1 mg / L to 50 mg / L. Optionally, the brightener includes one or more of 3-mercaptobenzimidazole, sodium polydithiopropane sulfonate, sodium isothiourea propane sulfonate, sodium 3-thiopropane sulfonate, and sodium formamide propane sulfonate. Optionally, the inhibitor includes one or more of polyethylene glycol, polypropylene glycol, polyether, and hydroxyethyl cellulose; Optionally, the leveling agent includes one or more of collagen, gelatin, polyethyleneimine, benzotriazole, and tetrahydrothiazolidinone.

9. The method for preparing porous copper foil according to any one of claims 1 to 6, characterized in that, At least one of the following conditions must be met: (1) The temperature of the copper-containing electrolyte is 40℃~70℃; (2) The current density of the electroplating is 25 A / dm. 2 ~50A / dm 2 ; (3) The rotational speed of the cathode roller is 2m / min to 15m / min.

10. A porous copper foil, characterized in that, The porous copper foil includes adjacent porous regions and dense regions. The total area of ​​the through-holes in the porous regions accounts for 5% to 50% of the area of ​​the porous regions. The ratio of the difference between the average thickness of the porous regions and the average thickness of the dense regions to the average thickness of the porous regions is less than or equal to 10%. The porous copper foil is prepared by the method described in any one of claims 1 to 9.

11. The porous copper foil as described in claim 10, characterized in that, At least one of the following conditions must be met: (1) The average thickness of the porous copper foil is 4μm~18μm; (2) The absolute value of the difference between the percentage of the total area of ​​the porous region to the area of ​​the porous region and the weight reduction rate of the porous region is ≤5%; (3) The through holes in the porous region are circular, and the diameter of the through holes is 50µm~1000µm; (4) The longitudinal tensile strength of the porous region is 200MPa~600MPa; (5) The transverse tensile strength of the porous region is 100MPa~500MPa; (6) The longitudinal fracture elongation of the porous region is ≥0.6%; (7) The transverse fracture elongation of the porous region is ≥0.4%.

12. A negative electrode current collector, characterized in that, The porous copper foil includes the porous copper foil prepared by the preparation method according to any one of claims 1 to 9, or the porous copper foil according to any one of claims 10 to 11.

13. A lithium-ion battery, characterized in that, Includes the negative electrode current collector as described in claim 12.

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