Copper plating solution, metallic copper layer comprising same and use of copper plating solution

Abstract

Provided in the present application are a copper plating solution, a metallic copper layer comprising same and the use of the copper plating solution. The copper plating solution comprises the following components having the following mass concentrations: copper sulfate: 80-150 g / L; sulfuric acid: 80-150 g / L; chloride ions: 60-90 mg / L; and a copper plating additive: 20-80 mg / L, wherein the copper plating additive comprises a combination of a brightener, a wetting agent and a leveling agent in a mass ratio of (0.5-1.5):(0.5-2.4):(0.025-4). Provided in the present application are the copper plating additive capable of accelerating copper deposition, improving the flatness and brightness of a plating and enhancing the binding force and spreadability between platings, and a composite current collector prepared from the copper plating solution containing the additive. The raw materials and products of the additive are free of pollution to the environment, and a preparation method therefor is simple and is also suitable for process production.

Description

Copper plating solution, metal copper layer containing same and application thereof Technical Field

[0001] The present application belongs to the technical field of electroplating materials, and specifically relates to a copper plating solution, a metal copper layer including the same, and applications thereof. Background Art

[0002] Currently, composite current collectors based on polymer films are receiving widespread attention and application in the new energy industry. Compared to traditional current collector materials, composite current collectors prepared based on polymer films offer advantages such as low cost, light weight, and excellent internal insulation. These advantages enable composite current collectors based on polymer films to be used in battery systems, not only reducing battery costs but also improving battery energy density and safety. Therefore, composite current collectors have a significant impact on the electrochemical performance of lithium-ion batteries.

[0003] Acid copper plating is a widely used copper plating process due to its advantages, including simple bath composition, high current efficiency, fast deposition rate, and easy wastewater treatment. The key to the quality of the copper plating layer lies in the selection and use of additives, which can affect the crystal structure of the copper layer, the uniformity of the plating, and the bonding strength between the plating layer and the substrate.

[0004] Currently, copper plating additives used in the prior art primarily include dye-based additives and non-dye-based additives. While dye-based copper plating additives offer a range of depth and brightness, the dye itself is unstable and easily decomposes, and the upper temperature limit for use during the electroplating process is relatively low, generally not exceeding 30°C. Furthermore, dyes are prone to salting out and coagulation, leading to defects such as pitting and pinholes in the coating. Furthermore, dye-based additives are unsuitable for large-scale industrial production and pose quality and environmental risks.

[0005] Therefore, in this field, there is an urgent need to develop a non-dye copper plating additive to solve the above problems.

[0006] Summary of the Invention

[0007] 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.

[0008] In response to the shortcomings of the prior art, the present application aims to provide a copper plating solution, a metallic copper layer including the same, and applications thereof. The present application provides a copper plating additive that can accelerate copper deposition, improve the flatness and brightness of the coating, and enhance the bonding strength and ductility between the coatings, as well as a composite current collector prepared from a copper plating solution containing the additive. The raw materials and products of the additive are environmentally friendly, the preparation method is simple, and the additive is suitable for industrial production.

[0009] To achieve this goal, this application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a copper plating solution comprising the following components in mass concentrations: 80-150 g / L copper sulfate, 80-150 g / L sulfuric acid, 60-90 mg / L chloride ions, and 20-80 mg / L copper plating additives;

[0011] The copper plating additive comprises a combination of a brightener, a wetting agent and a leveler in a mass ratio of (0.5-1.5):(0.5-2.4):(0.025-4).

[0012] The replacement of the inhibitory layer by the brightener in the copper plating additive provided by the present application promotes the copper ions to approach the electrode surface and can directly catalyze the Cu 2+ Reduction to Cu + , because during the copper deposition process Cu 2+ Reduction to Cu + It is the rate-controlling step in the whole process, therefore, adding brightener can accelerate the deposition of copper ions.

[0013] The leveling agent has the function of increasing cathode polarization and inhibiting deposition. On the microscopic concave and convex surface, the relatively more concentrated electric field and strong convection diffusion make it easier for the convex to adsorb the leveling agent than the concave, which makes the convex strongly inhibited. The concave is less inhibited due to reasons such as limited diffusion of the leveling agent. This inhibition difference leads to preferential deposition in the microscopic concave, and the coating eventually tends to be flat.

[0014] The wetting agent can be oriented and adsorbed at the interface between the cathode and the solution, thereby reducing the surface interfacial tension, enhancing the wettability and cathode polarization ability of the electrolyte and cathode interface, and improving the leveling and wettability of the deposited layer. After addition, it can increase the dispersion ability of copper ions, eliminate pinholes in the copper plating, and make the grains of the plating uniform, fine, and compact.

[0015] It should be noted that a single component additive in acid copper plating cannot achieve the ideal plating effect, and sometimes even has the opposite effect. The additives of each component are used in combination and the interaction between them is utilized to achieve better results.

[0016] In this application, by adjusting the mass ratio of brightener, wetting agent and leveling agent, the electroplating copper additive is kept within a reasonable range, thereby improving the deposition rate and mechanical properties of the copper plating layer. If the mass ratio is too low, the deposition rate will be low and there will be more defects. Otherwise, the deposition rate of copper ions will be inhibited and defects will occur.

[0017] In the present application, the mass concentration of the copper sulfate is 80-150 g / L, for example, it can be 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, etc.

[0018] In the present application, the role of copper sulfate is to provide the copper ions required for electroplating, as well as to improve the conductivity of the plating solution, prevent copper sulfate from hydrolyzing to form Cu(OH)2 precipitation, and at the same time improve the covering ability and dispersion ability of the plating solution.

[0019] In the present application, the mass concentration of the above-mentioned sulfuric acid is 80-150 g / L, for example, it can be 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, etc.

[0020] In the present application, the mass concentration of the above-mentioned chloride ions is 60-90 mg / L, for example, it can be 60 mg / L, 65 mg / L, 70 mg / L, 75 mg / L, 80 mg / L, 85 mg / L, 90 mg / L, etc.

[0021] In this application, chloride ions have a leveling effect in acid copper plating and can be added in the form of hydrochloric acid, along with other additives, to improve the structure of the cathode deposit. In copper electrodeposition, chloride ions can increase the copper concentration on the electrode surface, reduce activation polarization, and promote the growth of crystal nuclei.

[0022] In the present application, the mass concentration of the above copper plating additive is 20-80 mg / L, for example, it can be 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, etc.

[0023] In this application, the mass concentration of the copper plating additive is adjusted so that the electroplating copper additive is within a reasonable range, thereby improving the deposition rate and mechanical properties of the copper plating layer. If the mass concentration is too low, the deposition rate will be low and there will be more defects. Otherwise, the deposition rate of copper ions will be inhibited and defects will occur.

[0024] In the present application, the copper plating additive includes a combination of a brightener, a wetting agent and a leveler in a mass ratio of (0.5-1.5):(0.5-2.4):(0.025-4), for example, 0.5:0.5:0.025, 0.8:0.8:0.5, 1:1:1, 1.2:1.4:1.5, 1.5:1.6:2, 1:1.8:2.5, 1:2:3, 1:2.2:3.5, 1.5:2.4:4, etc.

[0025] In one embodiment, the copper plating solution includes the following components in mass concentrations: 120 g / L copper sulfate, 120 g / L sulfuric acid, 60 mg / L chloride ions, and 70 mg / L copper plating additives.

[0026] In one embodiment, the copper plating additive includes a combination of a brightener, a wetting agent, and a leveler in a mass ratio of 1:2:4.

[0027] In one embodiment, the brightener includes any one or a combination of at least two of sodium polydisulfide propane sulfonate, sodium phenyldisulfide propane sulfonate, sodium alcoholthiopropane sulfonate, sodium dimethylformamidopropane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithioformamidopropane sulfonate or isothioureapropanesulfonic acid inner salt, and sodium polydisulfide propane sulfonate may further be selected.

[0028] In one embodiment, the wetting agent includes any one or a combination of at least two of polyethylene glycol, polypropylene glycol, EO-PO block copolymer (abbreviated as MT-480), sodium lauryl sulfate, alkyl polyether sulfonate, polyvinyl pyrrolidone or sodium polyoxyethylene alkylphenol sulfonate, and can further be EO-PO block copolymer (abbreviated as MT-480).

[0029] It should be noted that the EO-PO block copolymer refers to a block copolymer formed by alternating arrangement of ethoxy groups (EO) and propoxy groups (PO).

[0030] In one embodiment, the leveler includes any one or a combination of at least two of 4-acetylpyridine, 4-benzoylpyridine, 4-ethylnicotinamide, 3-aminoquinoline, 2-mercaptobenzimidazole, N-ethylthiourea, N,N-2ethylthiourea, N-phenylthiourea, 1-phenyl 3-(5-pyridine)thiourea, 1,2-ethylenethiourea, ethylenethiourea, triazole-2-thiol, pyrimidine-2-thiol, tetrahydrothiazolium copper sulfide, sodium thiazolinyl dithiopropane sulfonate, sodium mercaptoimidazolepropane sulfonate, polyvinylamine alkylamine, polyethyleneimine alkyl salt or polyethyleneimine alkyl compound, and polyvinylamine alkylamine and / or polyethyleneimine alkyl salt may be further selected.

[0031] In a second aspect, the present application provides a metallic copper layer, which is prepared by the copper plating solution according to the first aspect.

[0032] In one embodiment, the thickness of the metal copper layer is 1-3 μm, and may further be 1 μm, for example, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, etc.

[0033] In a third aspect, the present application provides a process for preparing the metallic copper layer according to the second aspect, the process comprising the following steps:

[0034] The copper plating solution according to the first aspect is used to form a metal copper layer by chemical deposition.

[0035] In one embodiment, the chemical deposition method includes direct current plating or pulse plating.

[0036] In a fourth aspect, the present application provides a composite current collector, which includes a base layer, a metal conductive layer arranged on both sides of the base layer, a metal main layer arranged on both sides of the metal conductive layer, and a protective layer arranged on both sides of the metal main layer, wherein the metal main layer is the metal copper layer described in the second aspect.

[0037] In one embodiment, the base layer is a polymer layer.

[0038] In the present application, the material of the polymer layer includes but is not limited to one or more of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene or polyamide.

[0039] In one embodiment, the thickness of the base layer is 1-10 μm, and may further be 4.5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 4.5 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0040] In one embodiment, the thickness of the metal conductive layer is 400-1500 nm, for example, 400 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1500 nm, etc.

[0041] In the present application, the material of the metal conductive layer includes but is not limited to one or more of copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, titanium, silver, etc.

[0042] In the present application, the metal conductive layer is prepared by one or more methods such as physical vapor deposition (including but not limited to electron beam heating vacuum evaporation, laser heating vacuum evaporation, magnetron sputtering, etc.), chemical vapor deposition, electroplating or chemical plating.

[0043] In one embodiment, the thickness of the protective layer is 20-80 nm, for example, 20 nm, 40 nm, 60 nm, 80 nm, etc.

[0044] In the present application, the protective layer is used to prevent the metal main layer from being chemically corroded or physically damaged.

[0045] In the present application, the material of the protective layer includes one or more of benzotriazole and its derivatives (such as BTA, TTA, Irgamet 39) or silane coupling agents.

[0046] In the present application, the working principle of the protective layer is that the passivating agent first reacts with copper, and the generated compound adheres to the copper surface, thereby preventing further reaction between copper and sulfur; or the silane coupling agent is hydrolyzed to generate silanol (X-Si(OH)n), which combines with the metal surface and cross-links itself to form a dense protective film on the metal surface, thereby preventing the metal layer from further reacting with the air.

[0047] In a fifth aspect, the present application provides a secondary battery comprising a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode comprises a current collector and a negative electrode active material layer arranged on at least one side of the current collector, and the current collector is a composite current collector according to the fourth aspect.

[0048] Compared with the prior art, this application has the following beneficial effects:

[0049] The present application provides a copper plating solution, wherein the replacement of the inhibitory layer by the brightener in the copper plating additive provided by the present application promotes the copper ions to approach the electrode surface and can directly catalyze the Cu 2+ Reduction to Cu + , because during the copper deposition process Cu 2+ Reduction to Cu + It is the rate-controlling step in the whole process, therefore, adding brightener can accelerate the deposition of copper ions.

[0050] The leveling agent has the function of increasing cathode polarization and inhibiting deposition. On the microscopic concave and convex surface, the relatively more concentrated electric field and strong convection diffusion make it easier for the convex to adsorb the leveling agent than the concave, which makes the convex strongly inhibited. The concave is less inhibited due to reasons such as limited diffusion of the leveling agent. This inhibition difference leads to preferential deposition in the microscopic concave, and the coating eventually tends to be flat.

[0051] The wetting agent can be oriented and adsorbed at the interface between the cathode and the solution, thereby reducing the surface interfacial tension, enhancing the wettability and cathode polarization ability of the electrolyte and cathode interface, and improving the leveling and wettability of the deposited layer. After addition, it can increase the dispersion ability of copper ions, eliminate pinholes in the copper plating, and make the grains of the plating uniform, fine, and compact.

[0052] It should be noted that a single component additive in acid copper plating cannot achieve the ideal plating effect, and sometimes even has the opposite effect. The additives of each component are used in combination and the interaction between them is utilized to achieve better results.

[0053] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0054] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0055] Example 1

[0056] This embodiment provides a copper plating solution, which includes the following components in mass concentrations: 120 g / L copper sulfate, 120 g / L sulfuric acid, 60 mg / L chloride ions, and 70 mg / L copper plating additive.

[0057] The copper plating additives include a combination of a polydisulfide dipropylene sulfonate brightener, an MT-480 wetting agent, and a polyethyleneimine alkyl compound leveler (purchased from Jiangsu Leien Environmental Protection Technology Co., Ltd., model PN) in a mass ratio of 1:2:4.

[0058] This embodiment also provides a method for preparing the copper plating solution, which comprises the following steps:

[0059] Sodium polydisulfide dipropane sulfonate, MT-480 and polyethyleneimine alkyl compound are mixed in a mass ratio of 1:2:4 to obtain a copper plating additive, and the copper plating additive is dissolved in pure water.

[0060] The prepared copper plating additive, copper sulfate, sulfuric acid and chloride ions are mixed to obtain a copper plating solution.

[0061] Example 2

[0062] This embodiment provides a copper plating solution, which includes the following components in the following mass concentrations: 120 g / L copper sulfate, 120 g / L sulfuric acid, 60 mg / L chloride ions, and 41.5 mg / L copper plating additive.

[0063] The copper plating additive comprises a combination of a polydisulfide dipropylene sulfonate sodium brightener, a PEG wetting agent, a 2-mercaptobenzimidazole leveler and an ethylenethiourea leveler in a mass ratio of 1:1:0.025:0.05.

[0064] This embodiment also provides a method for preparing the copper plating solution, which comprises the following steps:

[0065] A copper plating additive is obtained by mixing a polydisulfide sodium dipropane sulfonate brightener, a PEG wetting agent, a 2-mercaptobenzimidazole leveling agent, and an ethylenethiourea leveling agent in a mass ratio of 1:1:0.025:0.05, and dissolving the copper plating additive in pure water.

[0066] The prepared copper plating additive, copper sulfate, sulfuric acid and chloride ions are mixed to obtain a copper plating solution.

[0067] Example 3

[0068] The difference between this embodiment and embodiment 1 is that sodium polydisulfide dipropane sulfonate is replaced with sodium 3-mercapto-1-propane sulfonate of the same content, and the other contents are the same as those in embodiment 1.

[0069] Example 4

[0070] The difference between this embodiment and embodiment 1 is that the polyethyleneimine alkyl compound is replaced by polyethyleneamine alkylamine of the same content, and the rest is the same as embodiment 1.

[0071] Example 5

[0072] The difference between this embodiment and embodiment 2 is that the solvent is replaced by an equal amount of ethanol instead of water, and the rest is the same as embodiment 2.

[0073] Example 6

[0074] The difference between this embodiment and embodiment 4 is that the mass ratio of sodium polydipropylene sulfonate, MT-480, and sodium polyethyleneimine alkyl in the copper plating additive is 1:1:2, and the rest is the same as embodiment 4.

[0075] Example 7

[0076] The difference between this embodiment and embodiment 2 is that the copper plating additives include a polydisulfide sodium dipropylene sulfonate brightener, a PEG wetting agent, and an ethylene thiourea leveler in a mass ratio of 1:1:0.5, and the rest are the same as in embodiment 2.

[0077] Example 8

[0078] The difference between this embodiment and embodiment 2 is that the copper plating additives include a polydisulfide dipropylene sulfonate sodium brightener, a PEG wetting agent, a polyethyleneimine alkyl compound leveler, and an ethylenethiourea leveler in a mass ratio of 1:2:0.5:0.05, and the rest are the same as in embodiment 2.

[0079] Example 9

[0080] The difference between this embodiment and embodiment 8 is that the copper plating additives include a poly (sodium disulfide dipropane sulfonate) brightener, a PEG wetting agent, and a polyethyleneimine alkyl compound leveler in a mass ratio of 1:2:1, and the rest are the same as in embodiment 8.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that the polysodium disulfide dipropane sulfonate brightener is not used in the copper plating additive, and the other aspects are the same as those in Example 1.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 1 is that MT-480 wetting agent is not used in the copper plating additive, and the other aspects are the same as Example 1.

[0085] Comparative Example 3

[0086] The difference between this comparative example and Example 1 is that no polyethyleneimine alkyl compound leveler is used in the copper plating additive, and the other aspects are the same as those in Example 1.

[0087] Comparative Example 4

[0088] The difference between this comparative example and Example 1 is that the copper plating additives include a polydisulfide dipropylene sulfonate sodium brightener, an MT-480 wetting agent, and a polyethyleneimine alkyl compound leveler in a mass ratio of 0.1:1:1, and the rest are the same as in Example 1.

[0089] Comparative Example 5

[0090] The difference between this comparative example and Example 1 is that the copper plating additives include a polydisulfide dipropylene sulfonate sodium brightener, an MT-480 wetting agent, and a polyethyleneimine alkyl compound leveler in a mass ratio of 1:3:6, and the rest are the same as in Example 1.

[0091] Application Examples 1 to 9 and Comparative Application Examples 1 to 5

[0092] The copper plating solutions provided in Examples 1 to 9 and Comparative Examples 1 to 5 were used to prepare composite current collectors. The preparation method is as follows:

[0093] The copper plating solution containing the copper plating solution additive was electroplated on a film plated with a conductive metal layer at 40° C. and a relative movement speed of 4 m / min for 5 minutes, then placed in an antioxidant solution and washed and dried to obtain a composite current collector with a thickness of 6.5 μm.

[0094] Test conditions

[0095] The composite current collectors provided in Application Examples 1 to 9 and Comparative Application Examples 1 to 5 were tested, and the test method was as follows:

[0096] ①Appearance inspection

[0097] Appearance testing is the most basic and commonly used inspection method. The coating's appearance must be uniform, smooth, and free of oxidative discoloration, grease, corrosion, burnt materials, dendritic or spongy cones, as well as areas where coating is required to be present. This application uses the visual brightness empirical assessment method to inspect the coating's appearance. The reference standards for the visual brightness empirical assessment method are as follows:

[0098] a. Level 1 (bright crystal surface): The surface of the coating is as bright as a mirror, and the face, facial features and eyebrows can be clearly seen;

[0099] b. The surface of the secondary (luminous) coating is bright, and the facial features and face can be seen, but the image is blurry;

[0100] c. Level 3 (semi-bright) coating is slightly bright, and only the outlines of facial features can be seen;

[0101] d. Level 4 (matte) coating surface is basically matte and the facial image cannot be seen.

[0102] The appearance inspection adopts the Hull cell experiment: the prepared composite copper plating additive is added to the copper foil electrolyte at an addition amount of 1 ml / L. The copper foil electrolyte parameters are 120 g / L copper sulfate, 120 g / L sulfuric acid, 60 mg / L chloride ions, and the current density is 3 ASD. The prepared Hull cell sheet is analyzed.

[0103] ②Deposition rate test

[0104] Use an electronic analytical balance to weigh the substrate before the Hull cell experiment (m1). Then weigh the substrate after electroless copper plating (m2). Calculate the deposition rate using the following formula: v = (m2 - m1) / (ρ·s·t).

[0105] Where: v is the deposition rate, ×10 -4 cm / h; ρ is the density of the test piece substrate before chemical copper plating, g / cm 3 ; s is the area of ​​the test piece substrate before chemical copper plating, cm 2 ; t is the chemical copper plating time, h.

[0106] ③Density test

[0107] The surface state of the composite current collector membrane was observed using a metallographic microscope.

[0108] ④ The adhesion between the polypropylene film and the metal layer in the composite current collector: a layer of Permacel P-94 double-sided tape was adhered to a 1 mm thick aluminum foil, the composite current collector was adhered on top of the double-sided tape, and a layer of ethylene acrylic acid copolymer film (DuPont Nurcel0903, thickness of 50 μm) was covered on the composite current collector. 5 N / m 2 The film was hot-pressed at 120°C for 10 seconds, cooled to room temperature, and cut into 150mm x 15mm strips. The ethylene acrylic acid copolymer film strip was fixed to the upper fixture of the tensile testing machine, and the remaining film strip was fixed to the lower fixture. After the two were fixed, they were peeled off at an angle of 180° and a speed of 100mm / min to test the peel force, i.e., the adhesion between the base layer and the metal layer.

[0109] ⑤ Composite current collector tensile strength: The test refers to the national standard GB / T 1040.3-2006.

[0110] The test results are shown in Table 1:

[0111] Table 1

[0112] As can be seen from Table 1, from Application Examples 1-4, when the ratio of brightener, wetting agent and leveling agent is within a reasonable range and the corresponding component types are regulated to be the preferred component types, the composite current collector provided by Application Example 4 has the best performance.

[0113] Meanwhile, the brighteners sodium 3-mercapto-1-propane sulfonate and sodium polydisulfide propane sulfonate have similar effects, while Application Example 6 shows that the leveling agent sodium polyethyleneimine alkyl (PN) is more effective than polyethyleneimine alkyl compound (GISS). While PN as a leveling agent achieves good brightness, the elongation is relatively poor. Application Example 5 shows that when ethanol is used as the solvent, the coating's appearance, elongation, and adhesion are also relatively poor, indicating that in this formulation, using ethanol as a solvent is detrimental to the coating's performance.

[0114] Combining Application Examples 2 and 7, it can be seen that using ethylene thiourea alone as a leveling agent is relatively ineffective. Combining ethylene thiourea with 2-mercaptobenzimidazole can achieve relatively better results. Application Example 8 demonstrates that the effect of leveling agents on coating performance is not simply additive; undue increases in agent dosage can degrade coating performance. Application Example 9 demonstrates that the optimal ratio of brightener, wetting agent, and leveling agent is 1:2:4.

[0115] From comparative application examples 1-3, it can be seen that the lack of brightener, wetting agent or leveling agent can lead to a decrease in coating performance. Comparative application examples 4-5 further illustrate that exceeding the reasonable ratio of reasonable reagents will also cause a decrease in coating performance.

[0116] The applicant declares that while the above-mentioned embodiments are used to illustrate the process of the present application, the present application is not limited to the above-mentioned process steps, which does not mean that the present application must rely on the above-mentioned process steps in order to be implemented. Those skilled in the art should understand that any improvements to the present application, equivalent replacements for the raw materials used in the present application, addition of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present application.

Claims

1. A copper plating solution comprising the following components in mass concentrations: 80-150 g / L copper sulfate, 80-150 g / L sulfuric acid, 60-90 mg / L chloride ions and 20-80 mg / L copper plating additives; The copper plating additive comprises a combination of a brightener, a wetting agent and a leveler in a mass ratio of (0.5-1.5):(0.5-2.4):(0.025-4).

2. The copper plating solution according to claim 1, wherein The copper plating solution comprises the following components in mass concentrations: 120 g / L copper sulfate, 120 g / L sulfuric acid, 60 mg / L chloride ions and 70 mg / L copper plating additives; Optionally, the copper plating additive includes a combination of a brightener, a wetting agent and a leveler in a mass ratio of 1:2:

4.

3. The copper plating solution according to claim 1 or 2, wherein The brightener includes any one or a combination of at least two of sodium polydisulfide propane sulfonate, sodium phenyldisulfide propane sulfonate, sodium alcoholthio propane sulfonate, sodium dimethylformamido propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium N,N-dimethyldithioformamido propane sulfonate or isothiourea propane sulfonic acid inner salt, and further sodium polydisulfide propane sulfonate may be selected; Optionally, the wetting agent includes any one or a combination of at least two of polyethylene glycol, polypropylene glycol, EO-PO block copolymer, sodium lauryl sulfate, alkyl polyether sulfonate, polyvinyl pyrrolidone or sodium polyoxyethylene alkylphenol sulfonate, and further may be EO-PO block copolymer; Optionally, the leveler includes any one or a combination of at least two of 4-acetylpyridine, 4-benzoylpyridine, 4-ethylnicotinamide, 3-aminoquinoline, 2-mercaptobenzimidazole, N-ethylthiourea, N,N-2ethylthiourea, N-phenylthiourea, 1-phenyl 3-(5-pyridine)thiourea, 1,2-ethylenethiourea, ethylenethiourea, triazole-2-thiol, pyrimidine-2-thiol, tetrahydrothiazolium copper sulfide, sodium thiazolinyl dithiopropane sulfonate, sodium mercaptoimidazolepropane sulfonate, polyvinylamine alkylamine, polyethyleneimine alkyl salt or polyethyleneimine alkyl compound, and polyvinylamine alkylamine and / or polyethyleneimine alkyl salt can be further selected.

4. A metallic copper layer prepared from the copper plating solution according to any one of claims 1 to 3.

5. The metallic copper layer according to claim 4, wherein: The thickness of the metal copper layer is 1-3 μm, and can be further 1 μm.

6. A process for preparing the metallic copper layer according to claim 4 or 5, comprising the following steps: The copper plating solution according to any one of claims 1 to 3 is used to form a metal copper layer by chemical deposition.

7. The method according to claim 6, wherein: The chemical deposition method includes direct current plating or pulse plating.

8. A composite current collector, comprising a base layer, a metal conductive layer arranged on both sides of the base layer, a metal main layer arranged on both sides of the metal conductive layer, and a protective layer arranged on both sides of the metal main layer, wherein the metal main layer is the metal copper layer according to claim 4 or 5.

9. The composite current collector according to claim 8, wherein: The base layer is a polymer layer; Optionally, the thickness of the base layer is 1-10 μm, and further optionally 4.5 μm; Optionally, the thickness of the metal conductive layer is 400-1500 nm; Optionally, the protective layer has a thickness of 20-80 nm. 10 . A secondary battery comprising a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode comprises a current collector and a negative electrode active material layer arranged on at least one side of the current collector, and the current collector is the composite current collector according to claim 8 or 9 .

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