Composite copper current collector having high mechanical properties, and preparation method therefor and use thereof

Abstract

A composite copper current collector having high mechanical properties, and a preparation method therefor and a use thereof. The composite copper current collector comprises a polymer film layer (1); and conductive layers (3) located on the surfaces of two sides of the polymer film layer (1). Each conductive layer (3) comprises a seed copper layer (31) and a thickened copper layer (30), the thickened copper layer comprises coarse-grained copper layers (301) and fine-grained copper layers (302), the coarse-grained copper layers (301) and the fine-grained copper layers (302) are alternately stacked, and a coarse-grained copper layer (301) is located on at least part of the surface of the seed copper layer (31). In the provided composite copper current collector, each fine-grained copper layer (302) provides good tensile strength and yield strength, each coarse-grained copper layer (301) provides a good elongation rate, and the two improve the mechanical properties of the composite copper current collector, enhancing the stability of the composite copper current collector during battery processing and cycling.

Description

Composite copper current collector with high mechanical properties and preparation method and application thereof Technical Field

[0001] The present application relates to the field of batteries, for example, a composite copper current collector with high mechanical properties and its preparation method and application. Background Art

[0002] At present, composite copper current collectors based on polymer films have received widespread attention and application in the new energy industry. The preparation of this composite copper current collector usually adopts the method of physical vapor deposition (PVD) to deposit a layer of copper metal on a polymer film (such as polyester, polyolefin, etc.), thereby preparing a composite copper current collector with good conductivity. Compared with traditional copper current collectors, composite copper current collectors based on polymer films have the characteristics of low cost, light weight, and good internal insulation. These characteristics enable the composite current collector to reduce the cost of the battery and improve the energy density and safety of the battery when used in the battery.

[0003] However, traditional composite copper current collectors suffer from poor mechanical properties, namely low tensile strength and yield strength. This leads to deformation and defects during the electrode preparation process, resulting in poor conductivity and ultimately a decrease in the battery's charge-discharge cycle performance. Therefore, in order to further improve the mechanical properties of composite copper current collectors, it is necessary to develop a new composite copper current collector to promote its application and promotion in batteries. Summary of the Invention

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0005] The present application aims to solve, at least to some extent, one of the technical problems in the related art. In response to the aforementioned problem of the need to improve the mechanical properties of a composite copper current collector, the present application proposes a composite copper current collector and a method for preparing the same. The composite copper current collector provided comprises a coarse-grained copper layer and a fine-grained copper layer. Through the interaction of the coarse-grained copper layer and the fine-grained copper layer, the mechanical properties of the composite copper current collector are improved, thereby promoting its machinability during battery preparation and thereby improving the battery's charge-discharge cycle performance.

[0006] Specifically, this application provides the following technical solutions:

[0007] The first aspect of the present application provides a composite copper current collector with high mechanical properties, comprising: a polymer film layer, and conductive layers located on both sides of the polymer film layer;

[0008] The conductive layer includes a seed copper layer and a thickened copper layer,

[0009] The thickened copper layer includes a coarse-grained copper layer and a fine-grained copper layer, the coarse-grained copper layer and the fine-grained copper layer are alternately stacked, and the coarse-grained copper layer is located on at least part of the surface of the seed copper layer.

[0010] Starting from the construction of the conductive layer structure, a multi-layer structure with an alternating arrangement of coarse-grained copper layers and fine-grained copper layers is created in the conductive layer of the composite copper current collector. In the multi-layer structure, the fine-grained copper layer provides good tensile strength and yield strength for the composite copper current collector, while the coarse-grained copper layer provides good elongation for the composite copper current collector. The combined effect of the two improves the mechanical properties of the composite copper current collector, thereby promoting the stability of the composite copper current collector during battery processing and cycling.

[0011] The high mechanical properties described in this application refer to a tensile strength of more than 240 MPa and a yield strength of more than 190 MPa.

[0012] According to an embodiment of the present application, the composite copper current collector described above may further include the following technical features:

[0013] In some embodiments of the present application, the coarse-grained copper layer and the fine-grained copper layer satisfy any one of the following conditions;

[0014] (a) The grain size d1 of the coarse-grained copper layer satisfies 100 ≤ d1 ≤ 500 nm, preferably 150 - 400 nm, and the grain size d2 of the fine-grained copper layer satisfies 0 < d2 < 100 nm, preferably 20 - 70 nm;

[0015] (b) The number of layers of the coarse-grained copper layer and the fine-grained copper layer is the same, both denoted as n, n ≥ 1, preferably, 1 ≤ n ≤ 10;

[0016] (c) The thickness of the thickened copper layer is 500 - 2000 nm, preferably 800 - 1200 nm, and the thickness of the seed copper layer is 40 - 100 nm;

[0017] (d) The relationship between the thickness t1 of the adjacent coarse-grained copper layer and the thickness t2 of the fine-grained copper layer is: 0.5 ≤ t1 / t2 ≤ 2, preferably, 0.8 ≤ t1 / t2 ≤ 1.3.

[0018] In some embodiments of the present application, the coarse-grained copper layer is obtained by the following method:

[0019] Electroplating is carried out using a first electroplating solution, and the first electroplating solution includes 80 - 130 g / L of copper sulfate, 80 - 160 g / L of sulfuric acid, 20 - 80 mg / L of chloride ions, 0.5 - 4 ppm of a first brightening agent, 1 - 5 ppm of a first leveling agent, and 20 - 100 ppm of a first wetting agent.

[0020] In some embodiments of the present application, the first brightener is selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptothiazoline;

[0021] In some embodiments of the present application, the first leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green;

[0022] In some embodiments of the present application, the first wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

[0023] In some embodiments of the present application, the fine-grained copper layer is prepared by the following method:

[0024] Electroplating is performed using a second electroplating solution, wherein the second electroplating solution includes 00-150 g / L copper sulfate, 80-160 g / L sulfuric acid, 20-80 mg / L chloride ions, 5-20 ppm of a second brightener, 1-5 ppm of a second leveler, and 100-500 ppm of a second wetting agent.

[0025] In some embodiments of the present application, the second brightener is selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptothiazoline.

[0026] In some embodiments of the present application, the second leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green.

[0027] In some embodiments of the present application, the second wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

[0028] In some embodiments of the present application, the polymer film layer is obtained by melt extrusion of a polymer material, and the polymer material is selected from at least one of polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polystyrene (PS), and polyimide (PI).

[0029] In some embodiments of the present application, the thickness of the polymer film layer is 1.0-10 μm.

[0030] In some embodiments of the present application, the composite current collector further includes a coating layer, which is located at least partially on the surface of the polymer film layer and between the conductive layer and the polymer film layer; the material of the coating layer is selected from at least one of aluminum oxide, silicon oxide, titanium oxide, nickel, chromium, titanium, nickel-chromium alloy, nickel-chromium-copper alloy, silicon-aluminum alloy, polyacrylic acid, polyacrylate, polyacrylamide, and polyurethane.

[0031] In some embodiments of the present application, the thickness of the primer layer is 1 to 10 nm, preferably 3 to 10 nm.

[0032] In some embodiments of the present application, the composite current collector further includes a protective layer, which is located on at least a portion of the surface of the conductive layer; the material of the protective layer is selected from at least one of nickel, chromium, nickel-chromium alloy, aluminum oxide, nickel oxide, chromium oxide, cobalt oxide, copper-chromium oxide, graphite, carbon black, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers, graphene and graphene oxide.

[0033] In some embodiments of the present application, the thickness of the protective layer is 10 to 100 nm, for example, 20 to 80 nm.

[0034] In some embodiments, the layer includes, from top to bottom, a first protective layer, a first conductive layer, a first primer layer, a polymer film layer, a second primer layer, a second conductive layer, and a second protective layer;

[0035] Wherein, the first primer layer is located on the upper surface of the polymer film layer, and the second primer layer is located on the lower surface of the polymer film layer;

[0036] The first conductive layer is located on the upper surface of the first base layer, and the second conductive layer is located on the lower surface of the second base layer;

[0037] The first protective layer is located on the upper surface of the first conductive layer, and the second protective layer is located on the lower surface of the second conductive layer;

[0038] The first conductive layer includes a first seed copper layer and a first thickened copper layer, and the second conductive layer includes a second seed copper layer and a second thickened copper layer;

[0039] The first seed copper layer is located on the upper surface of the first bottom layer, and the second seed copper layer is located on the upper surface of the second bottom layer.

[0040] The upper surface of the bottom layer.

[0041] The second aspect of the present application provides a method for preparing the composite copper current collector, comprising: obtaining a polymer film layer by melt extrusion and biaxial stretching;

[0042] A seed copper layer is deposited on both side surfaces of the polymer film layer, and then electroplating is performed in sequence on at least part of the surface of the seed copper layer to deposit a coarse-grained copper layer and a fine-grained copper layer respectively. The coarse-grained copper layer and the fine-grained copper layer are alternately stacked in sequence to form a thickened copper layer, and the seed copper layer and the thickened copper layer form a conductive layer.

[0043] According to an embodiment of the present application, the method further includes depositing a primer layer on at least a portion of the surface of the polymer film layer, wherein the primer layer is located between the conductive layer and the polymer film layer.

[0044] According to an embodiment of the present application, the method further includes depositing a protective layer on at least a portion of the surface of the conductive layer.

[0045] According to an embodiment of the present application, the step of depositing a coarse-grained copper layer includes:

[0046] Using the first plating solution, at an average cathode current density of 0.5-2A / dm 2 , electroplating is carried out under the condition of a plating solution temperature of 10-20°C, wherein the first electroplating solution includes 80-130g / L copper sulfate, 80-160g / L sulfuric acid, 20-80mg / L chloride ions, 0.5-4ppm first brightener, 1-5ppm first leveler, and 20-100ppm first wetting agent.

[0047] According to an embodiment of the present application, the first brightener is selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptothiazoline.

[0048] According to an embodiment of the present application, the first leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green.

[0049] According to an embodiment of the present application, the first wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

[0050] According to an embodiment of the present application, the step of depositing a fine-grained copper layer includes:

[0051] In the second plating solution, the average cathode current density is 2.5-8A / dm 2, electroplating is carried out under the condition of a plating solution temperature of 25-40°C, the second electroplating solution includes 100-150g / L copper sulfate, 80-160g / L sulfuric acid, 20-80mg / L chloride ions, 5-20ppm second brightener, 1-5ppm second leveler and 100-500ppm second wetting agent; according to an embodiment of the present application, the second brightener is selected from at least one of sodium polydisulfide dipropane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonic acid, and 2-mercaptothiazoline.

[0052] According to an embodiment of the present application, the second leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green;

[0053] According to an embodiment of the present application, the second wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

[0054] A third aspect of the present application provides a battery, comprising the composite copper current collector described in the first aspect or the composite copper current collector prepared according to the preparation method described in the second aspect.

[0055] The beneficial effects achieved by this application are:

[0056] This application proposes a new composite copper current collector. Due to its unique conductive layer structure, the mechanical properties of the composite copper current collector can be improved, and its stability in battery processing and circulation can be promoted. The preparation method is simple and easy, and it is easy to scale up production.

[0057] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0059] Figure 1 is a schematic structural diagram of a composite copper current collector provided according to an embodiment of the present application, wherein label 1 is a polymer film layer, 3 is a conductive layer, 30 is a thickened copper layer, 31 is a seed copper layer, 301 is a coarse-grained copper layer, and 302 is a fine-grained copper layer.

[0060] FIG2 is a schematic structural diagram of a composite copper current collector provided according to an embodiment of the present application, wherein reference numeral 1 is a polymer film layer, 2 is a base layer, 3 is a conductive layer, and 4 is a protective layer. DETAILED DESCRIPTION

[0061] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, but should not be understood as limiting the present application.

[0062] The present application provides a composite copper current collector with high mechanical properties, comprising: a polymer film layer;

[0063] and conductive layers located on both sides of the polymer film layer; the conductive layers include a seed copper layer and a thickened copper layer,

[0064] The thickened copper layer includes a coarse-grained copper layer and a fine-grained copper layer, the coarse-grained copper layer and the fine-grained copper layer are alternately stacked, and the coarse-grained copper layer is located on at least a portion of the surface of the seed copper layer.

[0065] The structural diagram of the provided composite copper current collector can be referred to as shown in FIG1 (it should be noted that the thickness of each layer structure in FIG1 is not completely in proportion and is only used as a structural example for reference to facilitate understanding by those skilled in the art).

[0066] This application starts with the construction of the conductive layer structure, and creates a multilayer structure in which coarse-grained copper layers and fine-grained copper layers are alternately arranged in the conductive layer of the composite copper current collector. The fine-grained copper layer in the multilayer structure provides the composite copper current collector with good tensile strength and yield strength, while the coarse-grained copper layer provides the composite copper current collector with good elongation. The two work together to improve the mechanical properties of the composite copper current collector, thereby promoting the stability of the composite copper current collector during battery processing and cycling.

[0067] The provided composite copper current collector may further include a base layer, which is located on at least a portion of the surface of the polymer film layer and between the conductive layer and the polymer film layer. The provided composite copper current collector may further include a protective layer, which is located on at least a portion of the surface of the conductive layer. According to a specific embodiment, the provided composite copper current collector is shown in FIG2 (it should be noted that the thickness of each layer structure in FIG1 is not completely in proportion, but is only used as a structural example for reference to facilitate understanding by those skilled in the art), which includes, from top to bottom, a first protective layer, a first conductive layer, a first base layer, a polymer film layer, a second base layer, a second conductive layer, and a second protective layer;

[0068] Wherein, the first primer layer is located on the upper surface of the polymer film layer, and the second primer layer is located on the lower surface of the polymer film layer;

[0069] The first conductive layer is located on the upper surface of the first base layer, and the second conductive layer is located on the lower surface of the second base layer;

[0070] The first protective layer is located on the upper surface of the first conductive layer, and the second protective layer is located on the lower surface of the second conductive layer;

[0071] The first conductive layer includes a first seed copper layer and a first thickened copper layer, and the second conductive layer includes a second seed copper layer and a second thickened copper layer;

[0072] The first seed copper layer is located on the upper surface of the first bottom layer, and the second seed copper layer is located on the upper surface of the second bottom layer.

[0073] In this article, "first" and "second" are not used to indicate order or importance, but are only used to distinguish when describing.

[0074] The conductive layer is located on at least part of the surface of the base layer and primarily serves to conduct electricity. The conductive layer comprises a seed copper layer and a thickened copper layer, with a thickness ranging from 500 to 2000 nm. If the composite conductive layer is too thin, the conductivity is poor; if it is too thick, the resulting composite current collector is too heavy, hindering the battery's energy density. Considering both conductivity and energy density, a more preferred thickness is 800 to 1200 nm. The conductive layer is made of copper and its alloys, preferably copper. The conductive layer consists of a seed copper layer and a thickened copper layer, with the seed copper layer located on the surface of the base layer providing a certain degree of conductivity, facilitating the preparation of the thickened copper layer. The seed copper layer has a thickness of 40 to 100 nm. If the thickness is too thin, the conductivity is too poor, making it impossible to ensure stable preparation of the thickened copper layer. If the thickness is too thick, the stable preparation of the thickened copper layer cannot be further promoted, resulting in high energy consumption and affecting the mechanical properties of the composite current collector. In accordance with specific embodiments, the seed copper layer is prepared by physical vapor deposition (such as magnetron sputtering or evaporation).

[0075] The thickened copper layer is a multilayer structure composed of alternating coarse-grained and fine-grained copper layers. The coarse-grained copper layer is closest to the seed copper layer, while the outermost layer is the fine-grained copper layer. This multilayer structure of alternating coarse-grained and fine-grained copper layers within the conductive layer provides the composite copper current collector with excellent tensile strength and yield strength, while the coarse-grained copper layer provides good elongation. Together, these two enhance the mechanical properties of the composite copper current collector, thereby promoting its stability during battery processing and cycling.

[0076] According to a specific embodiment, the number of layers of the coarse-grained copper layer and the fine-grained copper layer is the same, both denoted as n, where n is preferably 1, preferably 1, preferably 1 (for example, n is 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10). Within this range, the preparation efficiency and the obtained effect are better. For example, if n is too large, the preparation efficiency of the composite current collector will be too low and the preparation difficulty will increase.

[0077] In the multi-layer structure, the grain size of the coarse-grained copper layer needs to be within a suitable range. The grains should not be too large, as this will reduce the tensile strength and yield strength of the composite copper current collector. If the grains are too small, it is not easy to prepare, and it will also affect the relevant properties. The average grain size d1 of the coarse-grained copper layer satisfies: 100 The average crystal in the coarse-grained copper layer, for example, is about 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, and 500 nm. The preferred range is 150 nm - 400 nm, for example, about 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm.

[0078] In the multi-layer structure, the grain size of the fine-grained copper layer also needs to be within a suitable range. If the grains are too large, it will reduce the tensile strength and yield strength of the composite copper current collector of the composite copper current collector; if the grains are too small, it will reduce the elongation of the composite copper current collector. The average grain size d2 of the fine-grained copper layer satisfies: 0 < d2 < 100 nm, for example, about 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm. The preferred range is 20 nm - 70 nm, for example, about 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm.

[0079] In some embodiments of the present application, the relationship between the thickness t1 of the adjacent coarse-grained copper layer and the thickness t2 of the fine-grained copper layer is: 0.5: copper 1 / t2 ≤ t, preferably, 0.8, 1 / t2 ≤ t8 (for example, 0.9 - 1.1, specifically, it can be 0.8, 0.9, 1.0, 1.1, 1.2, 1.3).

[0080] In some embodiments of the present application, the coarse-grained copper layer is obtained by the following method:

[0081] Electroplating is carried out using a first electroplating solution, and the first electroplating solution includes 80 - 130 g / L copper sulfate, 80 - 160 g / L sulfuric acid, 20 - 80 mg / L chloride ions, 0.5 - 4 ppm of a first brightening agent, 1 - 5 ppm of a first leveling agent, and 20 - 100 ppm of a first wetting agent. According to specific embodiments, the coarse-grained copper layer can be prepared by electroplating, and its preparation process is that the average cathode current density is 0.5 - 2 A / dm 2 , and the bath temperature is 10 - 20. According to specific embodiments, the chloride ions mentioned can be hydrochloric acid.

[0082] In some embodiments of the present application, the fine-grained copper layer is obtained by the following method:

[0083] Electroplating is performed using a second electroplating solution comprising 00-150 g / L copper sulfate, 80-160 g / L sulfuric acid, 20-80 mg / L chloride ions, 5-20 ppm brightener, 1-5 ppm leveler, and 100-500 ppm wetting agent. According to a specific embodiment, a fine-grained copper layer can be prepared by electroplating, and the specific process can be an average cathode current density of 2.5-8 A / dm 2 , the plating solution temperature is 25-40°C. According to a specific embodiment, the chloride ion mentioned can be hydrochloric acid.

[0084] In some embodiments of the present application, the first brightener and the second brightener are each independently selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonic acid, and 2-mercaptothiazoline.

[0085] In some embodiments of the present application, the first leveler and the second leveler are each independently selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green.

[0086] In some embodiments of the present application, the first wetting agent and the second wetting agent are each independently selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

[0087] According to a specific embodiment, the first wetting agent and the second wetting agent used are the same, only the concentration is different; the first leveling agent and the second leveling agent used are the same, only the concentration is different; the first brightener and the second brightener mentioned are the same, only the concentration is different.

[0088] In some embodiments of the present application, the polymer film layer is obtained by melt extrusion of a polymer material (for example, by melt-extrusion-biaxial stretching), and the polymer material is selected from at least one of polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polystyrene (PS), and polyimide (PI).

[0089] Taking into account the application requirements of the composite copper current collector, while taking into account the difficulty and cost of the preparation process, in some embodiments of the present application, the thickness of the polymer film layer is 1.0-10, for example, about 1 for example, 2 for example, 3 for example, 4 for example, 5 for example, 6 for example, 7 for example, 8 for example, 9 for example, 10 for example.

[0090] The base layer is located on the surface of the polymer film layer and its function is to improve the adhesion between the polymer film layer and the metal layer.

[0091] In some embodiments of the present application, the material of the primer layer is selected from at least one of aluminum oxide, silicon oxide, titanium oxide, nickel, chromium, titanium, nickel-chromium alloy, nickel-chromium-copper alloy, silicon-aluminum alloy, polyacrylic acid, polyacrylate, polyacrylamide, and polyurethane.

[0092] The thickness of the primer layer is within a certain range. If the thickness of the primer layer is too thin, the improvement in the adhesion of the composite copper current collector is not significant enough. If the thickness of the primer layer is too thick, the adhesion cannot be further improved and the production efficiency is affected. In some embodiments of the present application, the thickness of the primer layer is 1 to 10 nm, for example, about 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm. According to a preferred embodiment, the thickness of the primer layer is 3 to 10 nm. In combination with the specific embodiment, the primer layer can be prepared by various methods such as physical vapor deposition or coating.

[0093] The protective layer is located on the surface of the conductive layer and can prevent the metal conductive layer from being chemically corroded or physically damaged. In some embodiments of the present application, the material of the protective layer is selected from at least one of nickel, chromium, nickel-chromium alloy, aluminum oxide, nickel oxide, chromium oxide, cobalt oxide, copper-chromium oxide, graphite, carbon black, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers, graphene, and graphene oxide;

[0094] According to specific embodiments, the thickness of the protective layer is 10 to 100 nm, preferably 20 to 80 nm, for example, about 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, or 80 nm. The thickness of the protective layer should not exceed one-tenth of the thickness of the conductive layer. Depending on the specific embodiment, the protective layer can be prepared by various methods such as physical vapor deposition, chemical vapor deposition, in-situ forming, coating, etc.

[0095] The present application also provides a method for preparing the composite copper current collector, comprising:

[0096] The polymer film layer is obtained by melt extrusion and biaxial stretching;

[0097] A seed copper layer is deposited on both side surfaces of the polymer film layer, and then electroplating is performed in sequence on at least part of the surface of the seed copper layer to deposit a coarse-grained copper layer and a fine-grained copper layer respectively. The coarse-grained copper layer and the fine-grained copper layer are alternately stacked in sequence to form a thickened copper layer, and the seed copper layer and the thickened copper layer form a conductive layer.

[0098] According to a specific embodiment, the provided preparation method further comprises: depositing a primer layer on at least a portion of the surface of the polymer film layer, wherein the primer layer is located between the conductive layer and the polymer film layer.

[0099] According to a specific embodiment, the provided preparation method further comprises: depositing a protective layer on at least a portion of the surface of the conductive layer.

[0100] According to a specific embodiment, the step of depositing a coarse-grained copper layer includes:

[0101] Using the first plating solution, at an average cathode current density of 0.5-2A / dm 2 , electroplating is carried out under the conditions of a plating solution temperature of 10-20 degrees, wherein the first electroplating solution includes 80-130g / L copper sulfate, 80-160g / L sulfuric acid, 20-80mg / L chloride ions, 0.5-4ppm first brightener, 1-5ppm first leveler, and 20-100ppm first wetting agent.

[0102] According to a specific embodiment, the first brightener is selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptothiazoline.

[0103] According to a specific embodiment, the first leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green.

[0104] According to a specific embodiment, the first wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

[0105] According to a specific embodiment, the step of depositing a fine-grained copper layer includes:

[0106] Using the second plating solution, the average cathode current density is 2.5-8A / dm 2 , electroplating is carried out under the condition that the plating solution temperature is 25-40, and the second electroplating solution includes 100-150g / L copper sulfate, 80-160g / L sulfuric acid, 20-80mg / L chloride ions, 5-20ppm second brightener, 1-5ppm second leveler and 100-500ppm second wetting agent.

[0107] According to a specific embodiment, the second brightener is selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptothiazoline.

[0108] According to a specific embodiment, the second leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green.

[0109] According to a specific embodiment, the second wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

[0110] The present application also provides a battery, comprising the composite copper current collector described above or the composite copper current collector prepared according to the preparation method described above.

[0111] The following examples illustrate the present invention. It should be noted that these examples are only intended to facilitate understanding by those skilled in the art and should not be considered as limiting the scope of protection of this application. The reagents used, unless otherwise specified, can be obtained commercially or homemade.

[0112] Example 1

[0113] Example 1 A composite copper current collector was prepared by the following method, including:

[0114] First, a primer layer was prepared on the surface of the polymer film. A 4.5-micron-thick biaxially oriented PET film (polyethylene terephthalate) was placed in a magnetron sputtering machine. Using a nickel-chromium alloy target, a 5-nm-thick primer layer was deposited on each side of the PET film. The specific process conditions were: a nickel-chromium target (purity: 99.99%), a target power of 5.0 kW,

[0115] The argon flow rate is 50 mL / min, the coating vacuum is 0.08 Pa, the coating time is 1 s, and the temperature of the main roller during the coating process is 0°C.

[0116] That is, a PET composite film with a base layer on the surface is prepared. Secondly, a conductive layer is prepared on the surface of the base layer:

[0117] (1) Preparation of seed copper layer: The PET composite film with the bottom layer prepared above was placed in a magnetron sputtering machine, and a copper target (purity: 99.99%) was used as the target material to prepare a seed copper layer with a thickness of 50 nm on each side of the composite film.

[0118] The preparation process of the copper layer is as follows: target power is 12 kW, argon flow rate is 50 mL / min, coating vacuum is 0.08 Pa, coating time is 5 s, and the temperature of the main roller during the coating process is 2 °C.

[0119] (2) Preparing a thickened copper layer: depositing a coarse-grained copper layer and a fine-grained copper layer on the surface of the composite film prepared above, wherein:

[0120] 1) Coarse-grained copper layer: Each layer has a thickness of 100 nm, the number of layers is 5, and the average grain size is 100 nm. The preparation conditions of each layer are as follows: the plating solution composition is: 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion (hydrochloric acid), 4 ppm sodium polydisulfide dipropane sulfonate, 2 ppm N, N-diethylthiourea, 80 ppm polyoxyethylene ether; the average cathode current density is 2.0 A / dm 2 , the plating solution temperature is 20℃, and the plating time is 24s;

[0121] 2) Fine-grained copper layer: The thickness of each layer is 100nm, the number of layers is 5, the average grain size is 20nm, and the preparation conditions of each layer are: the plating solution components are: 120g / L copper sulfate, 130g / L sulfuric acid, 50mg / L chloride ion (hydrochloric acid), 16ppm

[0122] Sodium polydisulfide dipropane sulfonate, 2ppm N,N-diethylthiourea, 200ppm polyoxyethylene ether; average cathode current density 7.6A / dm 2 , the plating solution temperature is 38℃, and the electroplating time is 6.5s.

[0123] Finally, a protective layer was prepared on the surface of the conductive layer. The prepared composite membrane was placed in a dipping solution containing 0.5 g / L chromic anhydride and 5 g / L sodium gluconate in water for 30 seconds. After dipping, the membrane was squeezed to remove the liquid and then dried in a 60°C oven to obtain a composite copper current collector.

[0124] Example 2

[0125] The same as Example 1, except that:

[0126] The average grain size of the coarse-grained copper layer was 150 nm. The preparation conditions were as follows: the plating solution composition was: 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion, 3.5 ppm sodium polydisulfide propane sulfonate, 2 ppm N,N-diethylthiourea, 80 ppm polyoxyethylene ether; the average cathode current density was 1.8 A / dm 2 , the plating solution temperature is 17℃, and the electroplating time is 27s.

[0127] Example 3

[0128] The same as Example 1, except that:

[0129] The average grain size of the coarse-grained copper layer is 300 nm. The preparation conditions are as follows: the plating solution composition is: 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion, 2.2 ppm sodium polydisulfide dipropane sulfonate, 2 ppm N, N-diethylthiourea, 80 ppm polyoxyethylene ether; the average cathode current density is 1.2 A / dm 2 , the plating solution temperature is 15℃, and the electroplating time is 45s.

[0130] Example 4

[0131] The same as Example 1, except that:

[0132] The average grain size of the coarse-grained copper layer is 400 nm. The preparation conditions are as follows: the plating solution composition is: 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion, 1.4 ppm sodium polydisulfide propane sulfonate, 2 ppm N, N-diethylthiourea, 80 ppm polyoxyethylene ether; the average cathode current density is 0.9 A / dm 2 , the plating solution temperature is 13℃, and the electroplating time is 60s.

[0133] Example 5

[0134] The same as Example 1, except that:

[0135] The average grain size of the coarse-grained copper layer is 500 nm. The preparation conditions are as follows: the plating solution composition is: 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion, 0.5 ppm sodium polydisulfide dipropane sulfonate, 2 ppm N, N-diethylthiourea, 80 ppm polyoxyethylene ether; the average cathode current density is 0.5 A / dm 2 , the plating solution temperature is 10℃, and the electroplating time is 105s.

[0136] Example 6

[0137] The same as Example 1, except that:

[0138] The average grain size of the fine-grained copper layer was 50 nm. The preparation conditions for each layer were as follows: the plating solution composition was: 120 g / L copper sulfate, 130 g / L sulfuric acid, 50 mg / L chloride ion, 12 ppm sodium polydisulfide propane sulfonate, 2 ppm N, N-diethylthiourea, 200 ppm polyoxyethylene ether; the average cathode current density was 5.0 A / dm 2 , the plating solution temperature is 32℃, and the electroplating time is 10s.

[0139] Example 7

[0140] The same as Example 1, except that:

[0141] The average grain size of the fine-grained copper layer was 70 nm. The preparation conditions for each layer were as follows: the plating solution composition was: 120 g / L copper sulfate, 130 g / L sulfuric acid, 50 mg / L chloride ion, 9 ppm sodium polydisulfide propane sulfonate, 2 ppm N,N-diethylthiourea, 200 ppm polyoxyethylene ether; the average cathode current density was 4.0 A / dm 2 , the plating solution temperature is 28℃, and the electroplating time is 12.5s.

[0142] Example 8

[0143] The same as Example 1, except that:

[0144] The average grain size of the fine-grained copper layer was 90 nm. The preparation conditions for each layer were as follows: the plating solution composition was: 120 g / L copper sulfate, 130 g / L sulfuric acid, 50 mg / L chloride ion, 7 ppm sodium polydisulfide propane sulfonate, 2 ppm N,N-diethylthiourea, 200 ppm polyoxyethylene ether; the average cathode current density was 3.0 A / dm 2 , the plating solution temperature is 25℃, and the electroplating time is 16s.

[0145] Example 9

[0146] The same as Example 1, except that:

[0147] In the thickened copper layer:

[0148] 1) Coarse-grained copper layer: Each layer has a thickness of 500 nm, the number of layers is 1, and the average grain size is 100 nm. The preparation conditions of each layer are as follows: the plating solution composition is: 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion, 4 ppm sodium polydisulfide dipropane sulfonate, 2 ppm N, N-diethylthiourea, 80 ppm polyoxyethylene ether; the average cathode current density is 2.0 A / dm 2 , the plating solution temperature is 20℃, and the plating time is 120s;

[0149] 2) Fine-grained copper layer: Each layer has a thickness of 500 nm, the number of layers is 1, the average grain size is 20 nm, and the preparation conditions for each layer are: the plating solution composition is: 120 g / L copper sulfate, 130 g / L sulfuric acid, 50 mg / L chloride ion, 16 ppm sodium polydisulfide propane sulfonate, 2 ppm N, N-diethylthiourea, 200 ppm polyoxyethylene ether; the average cathode current density is 7.6 A / dm 2 , the plating solution temperature is 38℃, and the electroplating time is 32.5s.

[0150] Example 10

[0151] Basically the same as Example 1, except that: in the thickened copper layer:

[0152] 1) Coarse-grained copper layer: Each layer has a thickness of 50 nm, the number of layers is 10, and the average grain size is 100 nm. The preparation conditions for each layer are as follows: the plating solution composition is: 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion, 4 ppm sodium polydisulfide dipropane sulfonate, 2 ppm N, N-diethylthiourea, 80 ppm polyoxyethylene ether; the average cathode current density is 2.0 A / dm 2 , the plating solution temperature is 20℃, and the plating time is 12s;

[0153] 2) Fine-grained copper layer: The thickness of each layer is 50nm, the number of layers is 10, the average grain size is 20nm, and the thickness of each layer is 10nm.

[0154] Preparation conditions: The plating solution composition is: 120g / L copper sulfate, 130g / L sulfuric acid, 50mg / L chloride ion, 16ppm sodium polydisulfide propane sulfonate, 2ppm N,N-diethylthiourea, 200ppm polyoxyethylene ether; average cathode current density 7.6A / dm 2 , the plating solution temperature is 38°C, and the electroplating time is 3.25s.

[0155] Comparative Example 1

[0156] The method is basically the same as Example 1, except that the thickened copper layer is one layer with a thickness of 1000 nm, and the preparation process is as follows:

[0157] The plating solution composition is: 100g / L copper sulfate, 100g / L sulfuric acid, 60mg / L chloride ion, 2ppm sodium polydisulfide propane sulfonate, 1ppm N,N-diethylthiourea, 100ppm polyoxyethylene ether; average cathode current density 2A / dm 2 , the plating solution temperature is 25℃, and the electroplating time is 260s.

[0158] Comparative Example 2

[0159] The method is basically the same as Example 1, except that the average grain size of the coarse-grained copper layer is 550 nm, and the preparation conditions are:

[0160] The plating solution consists of 90 g / L copper sulfate, 100 g / L sulfuric acid, 40 mg / L chloride ion, 0.3 ppm sodium polydisulfide propane sulfonate, 2 ppm N, N-diethylthiourea, and 80 ppm polyoxyethylene ether; the average cathode current density is 0.2 A / dm 2 , the plating solution temperature is 10℃, and the electroplating time is 270s.

[0161] Comparative Example 3

[0162] The method is basically the same as Example 1, except that the average grain size of the fine-grained copper layer is 120 nm, and the preparation conditions of each layer are:

[0163] The plating solution consists of 120 g / L copper sulfate, 130 g / L sulfuric acid, 50 mg / L chloride ion, 3 ppm sodium polydisulfide propane sulfonate, 2 ppm N, N-diethylthiourea, and 200 ppm polyoxyethylene ether; the average cathode current density is 2.0 A / dm 2 , the plating solution temperature is 25℃, and the electroplating time is 25s.

[0164] Test evaluation:

[0165] The tensile strength, yield strength, and elongation at break of the composite copper current collectors prepared in the above-mentioned embodiments and comparative examples were tested. The specific testing method is as follows: samples were taken longitudinally along the prepared composite current collector, and then the tensile strength, yield strength, and elongation at break were tested in accordance with the national standard GB / T1040.3-2006.

[0166] Table 1 Test results of different embodiments and comparative examples

[0167] From the table above we can see that:

[0168] (1) Combining the data given in Examples 1-10 and Comparative Example 1, it can be seen that: compared with the traditional composite copper current collector, the composite copper current collector prepared in the present application is provided with alternating coarse-grained copper layers and fine-grained copper layers, and the tensile strength, yield strength and elongation at break all show an upward trend, that is, the mechanical properties are improved.

[0169] (2) Combining the data of Examples 1-5 and Comparative Example 2, it can be seen that as the average grain size of the coarse-grained copper layer in the thickened copper layer increases, the tensile strength and yield strength of the composite current collector tend to decrease, while the elongation at break tends to increase. This is due to the increase in grain size. To ensure sufficient tensile strength and yield strength, the average grain size of the coarse-grained copper layer should not be too large.

[0170] (3) Combining the data presented in Examples 1, 6, 7, and 8 with Comparative Example 3, it can be seen that as the average grain size of the fine-grained copper layer in the thickened copper layer increases, the tensile strength and yield strength of the composite current collector decrease, while the elongation at break increases. This is due to the increase in grain size. To ensure sufficient tensile strength and yield strength, the average grain size of the fine-grained copper layer should not be too large.

[0171] In the description of this specification, the reference terms "one embodiment", "some embodiments", "implementation", "specific implementation", etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application.

[0172] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A composite copper current collector with high mechanical properties, comprising: A polymer film layer; And conductive layers located on both surface sides of the polymer film layer; Wherein the conductive layer includes a seed copper layer and a thickened copper layer, The thickened copper layer includes a coarse-grained copper layer and a fine-grained copper layer, the coarse-grained copper layer and the fine-grained copper layer are alternately laminated, and the coarse-grained copper layer is located on at least part of the surface of the seed copper layer.

2. The composite copper current collector according to claim 1, wherein: The coarse-grained copper layer and the fine-grained copper layer satisfy any one of the following conditions: (a) The grain size d1 of the coarse-grained copper layer satisfies 100 ≤ d1 ≤ 500 nm, preferably the grain size d1 of the coarse-grained copper layer is 150 - 400 nm, and the grain size d2 of the fine-grained copper layer satisfies 0 < d2 < 100 nm, preferably the grain size d2 of the fine-grained copper layer is 20 - 70 nm; (b) The number of layers of the coarse-grained copper layer and the fine-grained copper layer is the same, both denoted as n, n ≥ 1, preferably, 1 ≤ n ≤ 10; (c) The thickness of the thickened copper layer is 500 - 2000 nm, preferably the thickness of the thickened copper layer is 800 - 1200 nm, and the thickness of the seed copper layer is 40 - 100 nm; (d) The relationship between the thickness t1 of the adjacent coarse-grained copper layer and the thickness t2 of the fine-grained copper layer is: 0.5 ≤ t1 / t2 ≤ 2, preferably, 0.8 ≤ t1 / t2 ≤ 1.

3.

3. The composite copper current collector according to claim 1 or 2, wherein: The coarse-grained copper layer is obtained by the following method: Electroplating is carried out using a first electroplating solution, and the first electroplating solution includes 80 - 130 g / L copper sulfate, 80 - 160 g / L sulfuric acid, 20 - 80 mg / L chloride ions, 0.5 - 4 ppm of a first brightening agent, 1 - 5 ppm of a first leveling agent, and 20 - 100 ppm of a first wetting agent.

4. The composite copper current collector according to claim 3, wherein: The first brightening agent is selected from at least one of sodium polydithiopropane sulfonate, sodium 3-mercapto-1-propanesulfonate, sodium N,N-dimethyldithiocarbamoylpropane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptobenzothiazoline.

5. The composite copper current collector according to claim 3 or 4, wherein: The first leveling agent is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus green; optionally, the first wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

6. The composite copper current collector according to claim 1 or 2, wherein: The fine-grained copper layer is obtained by the following method: Electroplating is carried out using a second electroplating solution, and the second electroplating solution includes 100 - 150 g / L copper sulfate, 80 - 160 g / L sulfuric acid, 20 - 80 mg / L chloride ions, 5 - 20 ppm of a second brightening agent, 1 - 5 ppm of a second leveling agent, and 100 - 500 ppm of a second wetting agent; Optionally, the second brightening agent is selected from at least one of sodium polydithiopropane sulfonate, sodium 3-mercapto-1-propanesulfonate, sodium N,N-dimethyldithiocarbamoylpropane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptobenzothiazoline; Optionally, the second leveling agent is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus green; optionally, the second wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

7. The composite copper current collector according to claim 1 or 2, wherein: The polymer film layer is made by melt extrusion of a polymer material, and the polymer material is selected from at least one of polyethylene terephthalate (PET), polypropylene (PP), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polystyrene (PS), and polyimide (PI); Optionally, the polymer film layer has a thickness of 1.0-10 μm.

8. The composite copper current collector according to claim 7, wherein: The composite current collector further includes a coating layer, which is located on at least a portion of the surface of the polymer film layer and between the conductive layer and the polymer film layer; The material of the primer layer is selected from at least one of aluminum oxide, silicon oxide, titanium oxide, nickel, chromium, titanium, nickel-chromium alloy, nickel-chromium-copper alloy, silicon-aluminum alloy, polyacrylic acid, polyacrylate, polyacrylamide, and polyurethane; Optionally, the thickness of the primer layer is 1-10 nm, and further optionally, the thickness of the primer layer is 3-10 nm.

9. The composite copper current collector according to claim 8, wherein: The composite current collector further includes a protective layer, which is located on at least a portion of the surface of the conductive layer; The material of the protective layer is selected from at least one of nickel, chromium, nickel-chromium alloy, aluminum oxide, nickel oxide, chromium oxide, cobalt oxide, copper-chromium oxide, graphite, carbon black, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers, graphene and graphene oxide; Optionally, the thickness of the protective layer is 10-100 nm, preferably, the thickness of the protective layer is 20-80 nm.

10. The composite copper current collector according to claim 9, wherein: From top to bottom, it includes a first protective layer, a first conductive layer, a first primer layer, a polymer film layer, a second primer layer, a second conductive layer, and a second protective layer; Wherein, the first primer layer is located on the upper surface of the polymer film layer, and the second primer layer is located on the lower surface of the polymer film layer; The first conductive layer is located on the upper surface of the first base layer, and the second conductive layer is located on the lower surface of the second base layer; The first protective layer is located on the upper surface of the first conductive layer, and the second protective layer is located on the lower surface of the second conductive layer; The first conductive layer includes a first seed copper layer and a first thickened copper layer, and the second conductive layer includes a second seed copper layer and a second thickened copper layer; The first seed copper layer is located on the upper surface of the first bottom layer, and the second seed copper layer is located on the upper surface of the second bottom layer.

11. A method for preparing the composite copper current collector according to any one of claims 1 to 10, comprising the following steps: The polymer film layer is obtained by melt extrusion and biaxial stretching; A seed copper layer is deposited on both side surfaces of the polymer film layer, and then electroplating is performed in sequence on at least part of the surface of the seed copper layer to deposit a coarse-grained copper layer and a fine-grained copper layer respectively. The coarse-grained copper layer and the fine-grained copper layer are alternately stacked in sequence to form a thickened copper layer, and the seed copper layer and the thickened copper layer form a conductive layer.

12. The method for preparing a composite copper current collector according to claim 11, wherein: The preparation method further comprises depositing a primer layer on at least a portion of the surface of the polymer film layer, wherein the primer layer is located between the conductive layer and the polymer film layer; Optionally, the method further includes depositing a protective layer on at least a portion of the surface of the conductive layer.

13. The method for preparing a composite copper current collector according to claim 11 or 12, wherein: The step of depositing a coarse-grained copper layer comprises: Using the first plating solution, at an average cathode current density of 0.5-2A / dm 2 , electroplating is carried out under the condition of a plating solution temperature of 10-20° C., wherein the first electroplating solution includes 80-130 g / L copper sulfate, 80-160 g / L sulfuric acid, 20-80 mg / L chloride ion, 0.5-4 ppm first brightener, 1-5 ppm first leveler, and 20-100 ppm first wetting agent; Optionally, the first brightener is selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptothiazoline; Optionally, the first leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green; Optionally, the first wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

14. The method for preparing a composite copper current collector according to claim 11, wherein: The step of depositing a fine-grained copper layer comprises: Electroplating is performed using a second electroplating solution at an average cathodic current density of 2.5-8 A / dm2 and a bath temperature of 25-40°C, wherein the second electroplating solution comprises 100-150 g / L copper sulfate, 80-160 g / L sulfuric acid, 20-80 mg / L chloride ions, 5-20 ppm of a second brightener, 1-5 ppm of a second leveler, and 100-500 ppm of a second wetting agent; Optionally, the second brightener is selected from at least one of sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithiocarboxamide propane sulfonate, sodium phenothiazine-10-yl-propyl sulfonate, and 2-mercaptothiazoline; Optionally, the second leveler is selected from at least one of N,N-diethylthiourea, 2-mercaptopyridine, and Janus Green; optionally, the second wetting agent is selected from at least one of polyethylene glycol, polypropylene glycol, and polyoxyethylene ether.

15. A battery comprising the composite copper current collector according to any one of claims 1 to 10 or the composite copper current collector prepared by the preparation method according to any one of claims 11 to 14.

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