A heterogeneous copper alloy current collector, its preparation method and application

Abstract

This invention discloses a heterogeneous copper alloy current collector, its preparation method, and its application, belonging to the field of lithium-ion secondary battery technology. The heterogeneous copper alloy current collector includes a nano-copper alloy layer and a micron-crystalline copper layer, with the micron-crystalline copper layer disposed between adjacent nano-copper alloy layers. The outer layer is a hard layer, a high-strength copper alloy, used to improve the strength and conductivity of the current collector. The middle layer is a soft layer, made of micron-crystalline copper with high conductivity and high ductility. High strength, high ductility, and high conductivity are achieved through the interaction between the hard and soft layers. Testing shows that the peel strength of the heterogeneous copper alloy current collector provided by this invention is above 420 N / m, solving the problem of poor interlayer bonding in existing composite current collectors. The excellent peel strength of this heterogeneous copper alloy current collector indicates excellent interlayer bonding, while its superior strength, ductility, and good conductivity demonstrate that this heterogeneous structure effectively improves the overall strength and ductility of the current collector.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion secondary battery technology, specifically relating to a heterogeneous copper alloy current collector, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Lithium-ion batteries, as the mainstream portable energy storage devices, are widely used in electric vehicles, mobile communications, and energy storage. The negative electrode current collector is one of the key components of a lithium-ion battery, its main function being to carry the negative electrode active material and collect current. Traditional negative electrode current collectors mainly use copper foil, which suffers from low strength and poor corrosion resistance, limiting the performance and lifespan of lithium-ion batteries to some extent. To overcome these shortcomings, composite current collectors have emerged as a new type of current collector material in recent years, and have attracted widespread attention due to their superior performance.

[0004] Composite current collectors typically employ a sandwich structure, with the middle layer often made of polymer materials such as polyethylene and polypropylene. These polymer materials offer advantages such as low manufacturing cost, high safety, and high energy density. For example, patent CN 115763829A discloses a composite current collector that enhances conductivity, using a polymer support layer as the central layer, with a silver nanowire-reinforced conductive layer, a metal layer, and a graphene-reinforced conductive layer symmetrically arranged on both sides. Patent CN 116207270A discloses a composite current collector that involves mixing a masterbatch, conductive agent, coupling agent, and filler, followed by molding and stretching to obtain a polymer film layer. The polymer film layer is then roughened; a magnetron sputtering undercoating process is applied to the roughened polymer film layer; and a metal plating process is performed on the undercoated polymer film to obtain the composite current collector.

[0005] The aforementioned composite current collectors can enhance the conductivity of the current collector or the bonding force between the polymer layer and the metal layer. However, the bonding between the polymer layer and the outer metal layer is often a physical bond, resulting in weak adhesion and high resistance. This can lead to delamination between the outer metal layer and the polymer layer during battery charging and discharging, thus affecting battery performance and lifespan. Furthermore, the fabrication process of such composite current collectors is relatively complex, requiring multiple steps and sophisticated equipment, which further limits their widespread application in practice. Therefore, a new method for composite current collectors is needed that can improve conductivity while maintaining interlayer bonding strength and enhancing plasticity. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a heterogeneous copper alloy current collector, its preparation method, and its application. The heterogeneous copper alloy current collector provided by this invention solves the problem of poor interlayer bonding in composite current collectors and improves the conductivity and ductility of the current collector. To achieve the above objective, the technical solution of this invention is as follows:

[0007] In a first aspect, the present invention provides a heterogeneous copper alloy current collector, comprising a nano-copper alloy layer and a micron-crystalline copper layer, wherein the micron-crystalline copper layer is disposed between adjacent nano-copper alloy layers.

[0008] The heterogeneous copper alloy current collector provided by this invention has an outer hard layer, which is a high-strength nanocrystalline copper alloy used to improve the strength and conductivity of the current collector. The middle layer is a soft layer, which is a microcrystalline copper with high conductivity and high ductility. High strength, high ductility, and high conductivity are achieved through the interaction between the hard and soft layers.

[0009] It should be noted that the terms microcrystals and nanocrystals refer to grains of different sizes. Both nanocrystals and microcrystals are novel crystalline materials. The difference lies in their grain size; generally, grains smaller than 100 nm are called nanocrystals, while grains between 100 nm and 1 μm are called microcrystals.

[0010] In some embodiments of the present invention, the number of microcrystalline copper layers is 1-4.

[0011] In some embodiments of the present invention, the copper alloy includes one of copper-silver alloy, copper-tin alloy, copper-nickel alloy, and copper-gold alloy.

[0012] Preferably, the impurity element content in the copper alloy is less than or equal to 10%.

[0013] In some embodiments of the present invention, the thickness of the heterogeneous copper alloy current collector is 6-16 μm, and the thickness ratio of the nano-copper alloy layer to the microcrystalline copper layer is (1-3):(1-3).

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned heterogeneous copper alloy current collector, comprising the following steps:

[0015] Prepare copper alloy electroplating solution and micron-crystal copper electroplating solution respectively;

[0016] In the plating solution, according to the set structure, a nano-copper alloy layer and a micron-crystalline copper layer are electrodeposited on the substrate;

[0017] After peeling, cleaning, and drying, a heterogeneous copper alloy current collector is obtained.

[0018] It should be noted that the stripping refers to peeling the heterogeneous copper alloy current collector deposited on the substrate from the substrate. The substrate can be a nickel plate. To ensure the purity of the nano-copper alloy layer in the obtained heterogeneous copper alloy current collector, the nickel plate needs to undergo grinding, polishing, cleaning, degreasing, and activation treatments before use.

[0019] The dissimilar copper alloy current collector obtained after stripping is cleaned and dried to remove residual electroplating solution and impurities, ensuring its purity and stability. During the stripping process, appropriate stripping agents and process conditions can be used to ensure that the integrity and performance of the dissimilar copper alloy current collector are not affected.

[0020] In some embodiments of the present invention, the copper alloy electroplating solution contains a refining agent, which includes one or more of gelatin, thiourea, 2-mercaptobenzimidazole and sodium polydithiodipropanesulfonate.

[0021] Preferably, the concentration of the refining agent in the copper alloy electroplating solution is 0.005-0.05 g / L.

[0022] In some embodiments of the present invention, the micron-sized copper electroplating solution is one of the following: sulfate system, nitrate system, pyrophosphate system, and citrate system.

[0023] In some embodiments of the present invention, the electrodeposition includes one of direct current electrodeposition and pulsed electrodeposition.

[0024] Preferably, the current density during electrodeposition of the nano-copper alloy layer is 2-20 mA / cm². 2 The deposition time is 10-60 min.

[0025] Preferably, the current density during electrodeposition of the microcrystalline copper layer is 20-50 mA / cm². 2 The deposition time is 5-30 minutes.

[0026] It should be noted that the thickness ratio of the nano-copper alloy layer to the micron-sized copper layer can be controlled by adjusting the deposition time and current density.

[0027] Preferably, the electrodeposition process is carried out in a protective gas atmosphere, and preferably, the protective gas includes one of nitrogen, argon and helium.

[0028] In some embodiments of the present invention, after the electrodeposition of the nano-copper alloy layer or the micro-crystalline copper layer is completed, the electrodeposition is followed by water washing, acid washing, and water washing before the next deposition is performed.

[0029] A third aspect of the present invention provides a negative electrode sheet, the negative electrode sheet comprising the above-described heterogeneous copper alloy current collector or the heterogeneous copper alloy current collector prepared by the above-described preparation method, and a mixed slurry layer containing a negative electrode material disposed on the surface of the heterogeneous copper alloy current collector.

[0030] A fourth aspect of the present invention provides a lithium-ion battery comprising the above-described heterogeneous copper alloy current collector, the heterogeneous copper alloy current collector prepared by the above-described preparation method, or the above-described negative electrode sheet. The beneficial effects of the present invention are:

[0031] This invention provides a heterogeneous copper alloy current collector, comprising a nano-copper alloy layer and a microcrystalline copper layer, wherein the microcrystalline copper layer is disposed between adjacent nano-copper alloy layers. The outer layer is a hard layer, a high-strength copper alloy, used to enhance the strength and conductivity of the current collector. The middle layer is a soft layer, made of microcrystalline copper with high conductivity and high ductility. High strength, high ductility, and high conductivity are achieved through the interaction between the hard and soft layers. Testing shows that the peel strength of the heterogeneous copper alloy current collector provided by this invention is above 420 N / m, solving the problem of poor interlayer bonding in existing composite current collectors. The heterogeneous copper alloy current collector obtained through the embodiments of this invention exhibits excellent peel strength, indicating excellent interlayer bonding. Furthermore, it possesses superior strength, ductility, and good conductivity, demonstrating that this heterogeneous structure effectively improves the overall strength and ductility of the current collector.

[0032] The method for preparing the heterogeneous copper alloy current collector provided by this invention adopts a traditional electroplating process, which is simpler and conducive to large-scale production. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0034] Figure 1 This is a TEM image of the cross-section of the heterogeneous copper-silver alloy current collector obtained in Example 1 of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0036] In the following examples, all reagents or raw materials used were commercially available or self-made.

[0037] It should be noted that in the following examples, "silver nitrate 40mL / L 0.1M" means that 40mL of 0.1M silver nitrate solution is added to every 1L of solution A.

[0038] Example 1

[0039] A method for preparing a heterogeneous copper alloy current collector includes the following steps:

[0040] 1. Prepare a nano-copper-silver alloy electroplating solution. The solution formula is: potassium iodide 150g / L, potassium nitrate 10g / L, silver nitrate 40mL / L 0.1M to obtain solution A; copper sulfate 500g / L and potassium pyrophosphate 150g / L are dissolved in deionized water at a constant temperature to obtain solution B; mix solution A and solution B in equal proportion, and then add 0.005g / L thiourea.

[0041] 2. Prepare a micron-sized copper electroplating solution. The solution formula is: 75g / L copper sulfate and 180g / L sulfuric acid.

[0042] 3. Deposition of Nano-Copper-Silver Alloy Layer: In a nano-copper-silver alloy electroplating solution, a nano-copper-silver alloy layer is deposited on a nickel plate that has undergone grinding, polishing, cleaning, degreasing, and activation steps using direct current deposition. The deposition current density is 10 mA / cm². 2 The deposition time was 20 min, and the thickness was 2 μm.

[0043] 4. Deposition of a microcrystalline copper layer: In the microcrystalline copper electroplating solution, a microcrystalline copper layer is deposited on the nano-copper-silver alloy layer obtained in step 3, with a current density of 20 mA / cm². 2 The deposition time was 10 min, and the thickness was 2 μm.

[0044] 5. Deposit a nano-copper-silver alloy layer: Using the method in step 3, deposit a nano-copper-silver alloy layer on the micron-crystalline copper layer obtained in step 4.

[0045] 6. After deposition, a heterogeneous copper-silver alloy current collector with a hard layer to soft layer ratio of 2:1, a thickness ratio of 1:1, and a total thickness of 6μm is obtained by peeling off the nickel plate substrate. The heterogeneous copper-silver alloy current collector obtained by peeling is then cleaned and dried.

[0046] Figure 1 The image shows a TEM image of the cross-section of the heterogeneous copper-silver alloy current collector obtained in Example 1. As can be seen from the image, the upper layer of the heterogeneous copper-silver alloy current collector is composed of nanocrystals, and the middle layer is composed of microcrystals with a grain size of 1.5-2.5 μm.

[0047] Example 2

[0048] A method for preparing a heterogeneous copper alloy current collector includes the following steps:

[0049] 1. Prepare a nano-copper-silver alloy electroplating solution. The solution formula is: potassium iodide 150g / L, potassium nitrate 10g / L, silver nitrate 40mL / L 0.1M to obtain solution A; copper sulfate 500g / L and potassium pyrophosphate 150g / L are dissolved in deionized water at a constant temperature to obtain solution B; mix solution A and solution B in equal proportion, and then add 0.005g / L thiourea.

[0050] 2. Prepare a micron-sized copper electroplating solution. The solution formula is: 75g / L copper sulfate and 180g / L sulfuric acid.

[0051] 3. Deposition of Nano-Copper-Silver Alloy Layer: In a nano-copper-silver alloy electroplating solution, a nano-copper-silver alloy layer is deposited on a nickel plate that has undergone grinding, polishing, cleaning, degreasing, and activation steps using direct current deposition. The deposition current density is 10 mA / cm². 2 The deposition time was 40 min, and the thickness was 4 μm.

[0052] 4. Deposition of a microcrystalline copper layer: In the microcrystalline copper electroplating solution, a microcrystalline copper layer is deposited on the nano-copper-silver alloy layer obtained in step 3, with a current density of 20 mA / cm². 2 The deposition time was 10 min, and the thickness was 2 μm.

[0053] 5. Deposit a nano-copper-silver alloy layer: Using the method in step 3, deposit a nano-copper-silver alloy layer on the micron-crystalline copper layer obtained in step 4.

[0054] 6. After deposition, a heterogeneous copper-silver alloy current collector with a hard layer to soft layer ratio of 2:1, a thickness ratio of 2:1, and a total thickness of 10μm is obtained by peeling off the nickel plate substrate. The heterogeneous copper-silver alloy current collector obtained by peeling is then cleaned and dried.

[0055] Example 3

[0056] A method for preparing a heterogeneous copper alloy current collector includes the following steps:

[0057] 1. Prepare a nano-copper-silver alloy electroplating solution. The solution formula is: potassium iodide 150g / L, potassium nitrate 10g / L, silver nitrate 40mL / L 0.1M to obtain solution A; copper sulfate 500g / L and potassium pyrophosphate 150g / L are dissolved in deionized water at a constant temperature to obtain solution B; mix solution A and solution B in equal proportion, and then add 0.005g / L thiourea.

[0058] 2. Prepare a micron-sized copper electroplating solution. The solution formula is: 75g / L copper sulfate and 180g / L sulfuric acid.

[0059] 3. Deposition of Nano-Copper-Silver Alloy Layer: In a nano-copper-silver alloy electroplating solution, a nano-copper-silver alloy layer is deposited on a nickel plate that has undergone grinding, polishing, cleaning, degreasing, and activation steps using direct current deposition. The deposition current density is 10 mA / cm². 2 The deposition time was 30 min, and the thickness was 3 μm.

[0060] 4. Deposition of a microcrystalline copper layer: In the microcrystalline copper electroplating solution, a microcrystalline copper layer is deposited on the nano-copper-silver alloy layer obtained in step 3, with a current density of 20 mA / cm². 2 The deposition time was 5 minutes, and the thickness was 1 μm.

[0061] 5. Deposit a nano-copper-silver alloy layer: Using the method in step 3, deposit a nano-copper-silver alloy layer on the micron-crystalline copper layer obtained in step 4.

[0062] 6. After deposition, a heterogeneous copper-silver alloy current collector with a hard layer to soft layer ratio of 2:1, a thickness ratio of 3:1, and a total thickness of 7μm is obtained by peeling off the nickel plate substrate. The heterogeneous copper-silver alloy current collector obtained by peeling is then cleaned and dried.

[0063] Example 4

[0064] A method for preparing a heterogeneous copper alloy current collector includes the following steps:

[0065] 1. Prepare a nano-copper-silver alloy electroplating solution. The solution formula is: potassium iodide 150g / L, potassium nitrate 10g / L, silver nitrate 40mL / L 0.1M to obtain solution A; copper sulfate 500g / L and potassium pyrophosphate 150g / L are dissolved in deionized water at a constant temperature to obtain solution B; mix solution A and solution B in equal proportion, and then add 0.005g / L thiourea.

[0066] 2. Prepare a micron-sized copper electroplating solution. The solution formula is: 75g / L copper sulfate and 180g / L sulfuric acid.

[0067] 3. Deposition of Nano-Copper-Silver Alloy Layer: In a nano-copper-silver alloy electroplating solution, a nano-copper-silver alloy layer is deposited on a nickel plate that has undergone grinding, polishing, cleaning, degreasing, and activation steps using direct current deposition. The deposition current density is 10 mA / cm². 2 The deposition time was 20 min, and the thickness was 2 μm.

[0068] 4. Deposition of a microcrystalline copper layer: In the microcrystalline copper electroplating solution, a microcrystalline copper layer is deposited on the nano-copper-silver alloy layer obtained in step 3, with a current density of 20 mA / cm². 2 The deposition time was 20 min, and the thickness was 4 μm.

[0069] 5. Deposit a nano-copper-silver alloy layer: Using the method in step 3, deposit a nano-copper-silver alloy layer on the micron-crystalline copper layer obtained in step 4.

[0070] 6. After deposition, a heterogeneous copper-silver alloy current collector with a hard layer to soft layer ratio of 2:1, a thickness ratio of 1:2, and a total thickness of 8μm is obtained by peeling off the nickel plate substrate. The heterogeneous copper-silver alloy current collector obtained by peeling is then cleaned and dried.

[0071] Example 5

[0072] A method for preparing a heterogeneous copper alloy current collector includes the following steps:

[0073] 1. Prepare a nano-copper-silver alloy electroplating solution. The solution formula is: potassium iodide 150g / L, potassium nitrate 10g / L, silver nitrate 40mL / L 0.1M to obtain solution A; copper sulfate 500g / L and potassium pyrophosphate 150g / L are dissolved in deionized water at a constant temperature to obtain solution B; mix solution A and solution B in equal proportion, and then add 0.005g / L thiourea.

[0074] 2. Prepare a micron-sized copper electroplating solution. The solution formula is: 75g / L copper sulfate and 180g / L sulfuric acid.

[0075] 3. Deposition of Nano-Copper-Silver Alloy Layer: In a nano-copper-silver alloy electroplating solution, a nano-copper-silver alloy layer is deposited on a nickel plate that has undergone grinding, polishing, cleaning, degreasing, and activation steps using direct current deposition. The deposition current density is 10 mA / cm². 2 The deposition time was 20 min, and the thickness was 2 μm.

[0076] 4. Deposition of a microcrystalline copper layer: In the microcrystalline copper electroplating solution, a microcrystalline copper layer is deposited on the nano-copper-silver alloy layer obtained in step 3, with a current density of 20 mA / cm². 2 The deposition time was 10 min, and the thickness was 2 μm.

[0077] 5. Deposit a nano-copper-silver alloy layer: Using the method in step 3, deposit a nano-copper-silver alloy layer on the micron-crystalline copper layer obtained in step 4.

[0078] 6. Deposit a microcrystalline copper layer: Using the method in step 4, deposit a microcrystalline copper layer on the nano-copper-silver alloy layer obtained in step 5.

[0079] 7. Deposit a nano-copper-silver alloy layer: Using the method in step 3, deposit a nano-copper-silver alloy layer on the micron-crystalline copper layer obtained in step 6.

[0080] 8. After deposition, a heterogeneous copper-silver alloy current collector with a hard layer to soft layer ratio of 3:2, a thickness ratio of 1:1, and a total thickness of 10μm is obtained by peeling off the nickel plate substrate. The heterogeneous copper-silver alloy current collector obtained by peeling is then cleaned and dried.

[0081] Example 6

[0082] A method for preparing a heterogeneous copper alloy current collector includes the following steps:

[0083] 1. Prepare a nano copper-tin alloy electroplating solution. The solution formula is as follows: 150 g / L potassium pyrophosphate, 150 g / L copper pyrophosphate, 30 g / L stannous pyrophosphate, 10 g / L sodium citrate, 40 g / L dipotassium hydrogen phosphate, and 30 g / L aminotriacetic acid. Then add 0.02 g / L sodium polydisulfide dipropane sulfonate and 0.01 g / L thiourea.

[0084] 2. Prepare a micron-sized copper electroplating solution. The solution formula is: 75g / L copper sulfate and 180g / L sulfuric acid.

[0085] 3. Deposition of Nano-Copper-Tin Alloy Layer: In a nano-copper-tin alloy electroplating solution, a nano-copper-tin alloy layer is deposited on a nickel plate that has undergone grinding, polishing, cleaning, degreasing, and activation steps using direct current deposition. The deposition current density is 5 mA / cm². 2 The deposition time was 40 min, and the thickness was 2 μm.

[0086] 4. Deposition of a microcrystalline copper layer: In the microcrystalline copper electroplating solution, a microcrystalline copper layer is deposited on the nano-copper-tin alloy layer obtained in step 3, with a current density of 20 mA / cm². 2 The deposition time was 10 min, and the thickness was 2 μm.

[0087] 5. Deposit a nano-copper-tin alloy layer: Using the method in step 3, deposit a nano-copper-tin alloy layer on the micron-crystalline copper layer obtained in step 4.

[0088] 6. After deposition, a heterogeneous copper-tin alloy current collector with a hard layer to soft layer ratio of 2:1, a thickness ratio of 1:1, and a total thickness of 6μm is obtained by peeling off the nickel plate substrate. The heterogeneous copper-tin alloy current collector obtained by peeling is then cleaned and dried.

[0089] Comparative Example 1

[0090] A method for preparing a copper alloy current collector includes the following steps:

[0091] 1. Weigh out 50 g / L copper sulfate and 150 g / L potassium pyrophosphate, and dissolve them in deionized water at a constant temperature to obtain solution A. Weigh out 150 g / L potassium iodide, 10 g / L potassium nitrate, and 20 mL / L silver nitrate (0.1 M), and dissolve them in deionized water at a constant temperature to obtain solution B. Mix solution A obtained in step 1 and solution B obtained in step 2 in equal proportions to obtain solution C. Weigh out 0.005 g / L thiourea and dissolve it in solution C obtained in step 3 to obtain solution D.

[0092] 2. After polishing, washing with water, cleaning with anhydrous ethanol, and drying, the anode copper plate and cathode nickel plate are placed into solution D obtained in step 1, and deposition is performed using a DC power supply with a current density of 10 mA / cm². 2 The deposition time was 120 min, the constant temperature was 50℃, the stirring speed was 200 rpm, and the thickness was 12 μm. Nanocrystalline copper-silver alloy current collectors were obtained by peeling them off from the substrate.

[0093] Comparative Example 2

[0094] A method for preparing a copper current collector includes the following steps:

[0095] 1. Weigh out 75 g / L copper sulfate and 180 g / L concentrated sulfuric acid and dissolve them in deionized water at room temperature to obtain a micron-sized copper electroplating solution.

[0096] 2. After polishing, washing with water, cleaning with anhydrous ethanol, and drying, the anode copper plate and cathode stainless steel plate are placed into the nanocrystalline copper electroplating solution obtained in step 1, and deposition is performed using a DC power supply with a current density of 20 mA / cm². 2 The deposition time was 60 min, the constant temperature was 25℃, the stirring speed was 500 rpm, and the thickness was 12 μm.

[0097] 3. After deposition, micron-sized copper foil current collectors are peeled off from the nickel plate substrate. The peeled micron-sized copper foil current collectors are then cleaned and dried.

[0098] The tensile strength, elongation, conductivity, and peel strength of the current collectors obtained in the examples and comparative examples were tested. The specific testing methods are as follows:

[0099] (1) Tensile strength and elongation

[0100] The test was conducted in accordance with standard GB / T 228-2002.

[0101] (2) Conductivity

[0102] The resistance value was measured using a constant current source and a multimeter, and the conductivity was calculated by combining the length and cross-sectional area.

[0103] (3) Peel strength

[0104] The heterogeneous copper alloy current collector obtained in the example was prepared into a strip sample with a length of 200±0.5mm and a width of 15±0.25mm. Then, its peel strength was tested using a tensile testing machine with a clamping distance of 100±0.1mm and a tensile speed of 10mm / min. The test results were recorded, and the average value was taken as the peel strength of the corresponding example.

[0105] The test results are shown in Table 1.

[0106] Table 1 shows the tensile strength, elongation, electrical conductivity, and peel strength of the materials obtained in the examples and comparative examples.

[0107]

[0108] The bonding force between the polymer layer and the metal layer of the current collector, which is a polymer material in the middle, is low. For example, in patent CN115763829 A, the adhesion force is between 100-110 N / m, and in patent CN 116207270 A, the peel strength is between 229-240 N / m. However, the peel strength of the heterogeneous copper alloy current collector obtained in this embodiment of the invention is above 420 N / m. It is evident that the heterogeneous copper alloy current collector obtained through this embodiment of the invention has excellent peel strength, indicating excellent interlayer bonding force. Furthermore, it exhibits superior strength, ductility, and good electrical conductivity, demonstrating that this heterogeneous structure effectively improves the overall strength and plasticity of the current collector. Moreover, this preparation method uses a traditional electroplating process, which is simpler and conducive to large-scale production.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heterogeneous copper alloy current collector, characterized in that, It includes a nano-copper alloy layer and a micron-crystalline copper layer, wherein the micron-crystalline copper layer is disposed between adjacent nano-copper alloy layers; The preparation method of heterogeneous copper alloy current collector includes the following steps: Prepare copper alloy electroplating solution and micron-crystal copper electroplating solution respectively; In the plating solution, according to the set structure, a nano-copper alloy layer and a micron-crystalline copper layer are electrodeposited on the substrate; Peeling, cleaning, and drying yield a heterogeneous copper alloy current collector; When electrodepositing micron-sized copper layers, the current density is 20-50 mA / cm². 2 The deposition time is 5-30 min; After electrodeposition of the nano-copper alloy layer or the micron-crystalline copper layer, the copper is washed with water, acid-washed, and then washed with water again before the next deposition is performed. The peel strength of the heterogeneous copper alloy current collector is above 420 N / m.

2. The heterogeneous copper alloy current collector as described in claim 1, characterized in that, The number of layers in the micron-sized copper layer is 1-4.

3. The heterogeneous copper alloy current collector as described in claim 1, characterized in that, The copper alloy includes one of copper-silver alloy, copper-tin alloy, copper-nickel alloy, and copper-gold alloy.

4. The heterogeneous copper alloy current collector as described in claim 3, characterized in that, The impurity element content in the copper alloy is less than or equal to 10%.

5. The heterogeneous copper alloy current collector as described in claim 1, characterized in that, The thickness of the heterogeneous copper alloy current collector is 6-16 μm, and the thickness ratio of the nano-copper alloy layer to the micron-crystalline copper layer is (1-3):(1-3).

6. A method for preparing a heterogeneous copper alloy current collector according to any one of claims 1-5, characterized in that, Includes the following steps: Prepare copper alloy electroplating solution and micron-crystal copper electroplating solution respectively; In the plating solution, according to the set structure, a nano-copper alloy layer and a micron-crystalline copper layer are electrodeposited on the substrate; After peeling, cleaning, and drying, a heterogeneous copper alloy current collector is obtained.

7. The preparation method according to claim 6, characterized in that, The copper alloy electroplating solution contains a refining agent, which includes one or more of gelatin, thiourea, 2-mercaptobenzimidazole, and sodium polydithiodipropane sulfonate.

8. The preparation method according to claim 7, characterized in that, The concentration of the refining agent in the copper alloy electroplating solution is 0.005-0.05 g / L; the micron-sized copper electroplating solution is one of the following: sulfate system, nitrate system, pyrophosphate system, and citrate system.

9. The preparation method according to claim 6, characterized in that, The electrodeposition includes one of direct current electrodeposition and pulse electrodeposition; During electrodeposition of nano-copper alloy layers, the current density is 2-20 mA / cm². 2 The deposition time is 10-60 min; When electrodepositing micron-sized copper layers, the current density is 20-50 mA / cm². 2 The deposition time is 5-30 min; All electrodeposition processes are carried out in a protective gas atmosphere.

10. The preparation method according to claim 9, characterized in that, The protective gas includes one of nitrogen, argon, and helium.

11. A negative electrode sheet, characterized in that, The negative electrode sheet includes a heterogeneous copper alloy current collector as described in any one of claims 1-4 or a heterogeneous copper alloy current collector prepared by any one of claims 6-10, and a mixed slurry layer containing negative electrode material disposed on the surface of the heterogeneous copper alloy current collector.

12. A lithium-ion battery, characterized in that, It includes the heterogeneous copper alloy current collector according to any one of claims 1-4, the heterogeneous copper alloy current collector prepared by any one of the preparation methods according to claims 6-10, or the negative electrode sheet according to claim 11.

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