Copper plating solution, metal copper layer comprising copper plating solution and application of copper plating solution

Abstract

The invention provides a copper plating solution, a metal copper layer comprising the copper plating solution and application of the metal copper layer. The copper plating solution comprises the following components in mass concentration: 80-150 g / L of copper sulfate, 80-150 g / L of sulfuric acid, 60-90 mg / L of chloride ions and 20-80 mg / L of a copper plating additive; the copper plating additive comprises a combination of a brightening agent, a wetting agent and a leveling agent according to the mass ratio of (0.5-1.5): (0.5-2.4): (0.025-4). According to the copper plating additive and the composite current collector prepared from the copper plating liquid containing the additive, copper deposition can be accelerated, the flatness and brightness of plating layers can be improved, meanwhile, the binding force and extensibility between the plating layers can be enhanced, raw materials and products of the additive are free of pollution to the environment, the preparation method is simple, and the preparation cost is low. And the method is also suitable for process production.

Description

Technical Field

[0001] The invention belongs to the technical field of electroplating materials, and in particular relates to a copper plating solution, a metal copper layer comprising the same and applications thereof. Background Art

[0002] At present, composite current collectors based on polymer films have received extensive attention and applications in the new energy industry. Compared with traditional current collector materials, composite current collectors prepared based on polymer films have the characteristics of low cost, light weight, and good internal insulation. These characteristics make it possible for composite current collectors prepared based on polymer films to be used in battery systems, which can not only reduce the cost of batteries, but also improve the energy density and safety of batteries. Therefore, composite current collectors have a great influence on the electrochemical performance of lithium batteries.

[0003] Acid copper plating process has become one of the most widely used copper plating processes due to its advantages of simple plating solution composition, high current efficiency, fast deposition speed and easy wastewater treatment. The key to determining 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 layer, and the bonding strength between the plating layer and the substrate.

[0004] At present, the copper plating additives used in the prior art mainly include dye-type additives and non-dye-type additives. Although dye-type copper plating additives have a certain depth range and brightness range, the nature of the dye itself is unstable and easily decomposed, and the upper limit temperature used in the electroplating process is relatively low, generally not exceeding 30°C. In addition, the dye is prone to salting out and flocculation, resulting in defects such as pitting and pinholes in the coating; furthermore, dye-type additives are not conducive to large-scale industrial production, and there are also some quality problems and environmental pollution problems.

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

[0006] In view of the deficiencies of the prior art, the object of the present invention is to provide a copper plating solution, a metal copper layer including the same and its application. The present invention 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, and a composite current collector prepared from the copper plating solution containing the additive, and the raw materials and products of the additive are environmentally friendly, the preparation method is simple, and it is also suitable for process production.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention 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;

[0009] 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).

[0010] The replacement of the inhibition layer by the brightener in the copper plating additive provided by the present invention promotes the copper ions to approach the electrode surface and can directly catalyze the Cu 2+ Reduction to Cu + , since 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.

[0011] 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, while the concave is less inhibited due to the limited diffusion of the leveling agent. This inhibition difference leads to preferential deposition of the microscopic concave, and finally the coating tends to be flat.

[0012] The wetting agent can be arranged in a directional manner at the interface between the cathode and the solution and produce an adsorption effect, which reduces the surface interfacial tension, enhances the wettability of the electrolyte and cathode interface and the cathode polarization ability, improves the leveling and wettability of the deposited layer, and after being added, 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.

[0013] 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 a better effect.

[0014] In the present invention, by adjusting the mass ratio of brightener, wetting agent and leveling agent, 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 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.

[0015] In the present invention, 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.

[0016] In the present invention, the role of copper sulfate is to provide copper ions required for electroplating, improve the conductivity of the plating solution, prevent copper sulfate from hydrolyzing to form Cu(OH)2 precipitation, and improve the covering ability and dispersibility of the plating solution.

[0017] In the present invention, 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.

[0018] In the present invention, 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.

[0019] In the present invention, in acid copper plating, chloride ions have a leveling effect and can be added in the form of hydrochloric acid to improve the cathode deposit structure in combination with other additives. In copper electrodeposition, chloride ions can increase the concentration of copper on the electrode surface, reduce activation polarization, and help the growth of crystal nuclei.

[0020] In the present invention, the mass concentration of the copper plating additive is 20-80 mg / L, for example, 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, etc.

[0021] In the present invention, 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.

[0022] In the present invention, 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, it can be 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.

[0023] Preferably, 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.

[0024] Preferably, the copper plating additive comprises a combination of a brightener, a wetting agent and a leveler in a mass ratio of 1:2:4.

[0025] Preferably, 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, preferably sodium polydisulfide propane sulfonate.

[0026] Preferably, the wetting agent includes any one 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, or a combination of at least two thereof, preferably EO-PO block copolymer (abbreviated as MT-480).

[0027] 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).

[0028] Preferably, the leveler comprises 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, preferably polyvinylamine alkylamine and / or polyethyleneimine alkyl salt.

[0029] In a second aspect, the present invention provides a metallic copper layer, wherein the metallic copper layer is prepared by the copper plating solution according to the first aspect.

[0030] Preferably, the thickness of the metal copper layer is 1-3 μm, preferably 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.

[0031] In a third aspect, the present invention provides a process for preparing the metallic copper layer according to the second aspect, the process comprising the following steps:

[0032] The copper plating solution according to the first aspect is used to form a metal copper layer by chemical deposition.

[0033] Preferably, the chemical deposition method includes direct current plating or pulse plating.

[0034] In a fourth aspect, the present invention provides 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 described in the second aspect.

[0035] Preferably, the base layer is a polymer layer.

[0036] In the present invention, 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.

[0037] Preferably, the thickness of the base layer is 1-10 μm, preferably 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.

[0038] Preferably, 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.

[0039] In the present invention, 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 and the like.

[0040] In the present invention, 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.

[0041] Preferably, the thickness of the protective layer is 20-80 nm, for example, 20 nm, 40 nm, 60 nm, 80 nm, etc.

[0042] In the present invention, the protective layer is used to prevent the metal main layer from being chemically corroded or physically damaged.

[0043] In the present invention, the material of the protective layer includes one or more of benzotriazoles and their derivatives (such as BTA, TTA, Irgamet39) or silane coupling agents.

[0044] In the present invention, 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 copper and sulfur from further reacting; or the silane coupling agent is hydrolyzed to generate silanol (X-Si(OH)n), and the silanol 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.

[0045] In a fifth aspect, the present invention 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.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention provides a copper plating solution, wherein the replacement of the inhibition layer by the brightener in the copper plating additive provided by the invention promotes the approach of copper ions to the electrode surface, and can directly catalyze the Cu 2+ Reduction to Cu + , since 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.

[0048] 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, while the concave is less inhibited due to the limited diffusion of the leveling agent. This inhibition difference leads to preferential deposition of the microscopic concave, and finally the coating tends to be flat.

[0049] The wetting agent can be arranged in a directional manner at the interface between the cathode and the solution and produce an adsorption effect, which reduces the surface interfacial tension, enhances the wettability of the electrolyte and cathode interface and the cathode polarization ability, improves the leveling and wettability of the deposited layer, and after being added, 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.

[0050] 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 a better effect. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] Example 1

[0053] The present 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 additives.

[0054] The copper plating additives include a combination of a sodium polydisulfide dipropane sulfonate brightener, an MT-480 wetting agent, and a polyethyleneimine alkyl compound leveler (purchased from Jiangsu Rayne Environmental Protection Technology Co., Ltd., model PN) in a mass ratio of 1:2:4.

[0055] This embodiment also provides a method for preparing the copper plating solution, which comprises the following steps:

[0056] 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.

[0057] The prepared copper plating additive, copper sulfate, sulfuric acid and chloride ions are mixed to obtain a copper plating solution.

[0058] Example 2

[0059] The present 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 41.5 mg / L copper plating additives.

[0060] The copper plating additive comprises a combination of a sodium polydisulfide dipropane sulfonate brightener, a PEG wetting agent, a 2-mercaptobenzimidazole leveler and an ethylenethiourea leveler in a mass ratio of 1:1:0.025:0.05.

[0061] This embodiment also provides a method for preparing the copper plating solution, which comprises the following steps:

[0062] A copper plating additive is obtained by mixing a polydisulfide sodium dipropane sulfonate brightener, a PEG wetting agent, a 2-mercaptobenzimidazole leveler, and an ethylenethiourea leveler in a mass ratio of 1:1:0.025:0.05, and dissolving the copper plating additive in pure water.

[0063] The prepared copper plating additive, copper sulfate, sulfuric acid and chloride ions are mixed to obtain a copper plating solution.

[0064] Example 3

[0065] The difference between this embodiment and embodiment 1 is that sodium polydisulfide propane sulfonate is replaced by sodium 3-mercapto-1-propane sulfonate of the same content, and the rest is the same as embodiment 1.

[0066] Example 4

[0067] 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.

[0068] Example 5

[0069] 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.

[0070] Example 6

[0071] The difference between this embodiment and embodiment 4 is that the mass ratio of sodium polydipropane disulfide 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.

[0072] Example 7

[0073] The difference between this embodiment and embodiment 2 is that the copper plating additives include a polydisulfide sodium dipropane 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.

[0074] Example 8

[0075] The difference between this embodiment and embodiment 2 is that the copper plating additives include a polydisulfide sodium dipropane sulfonate 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.

[0076] Example 9

[0077] The difference between this embodiment and embodiment 8 is that the copper plating additives include a poly (sodium disulfide propane 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.

[0078] Comparative Example 1

[0079] The difference between this comparative example and Example 1 is that no sodium polydisulfide dipropane sulfonate brightener is used in the copper plating additive, and the other contents are the same as those in Example 1.

[0080] Comparative Example 2

[0081] 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.

[0082] Comparative Example 3

[0083] 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 Example 1.

[0084] Comparative Example 4

[0085] The difference between this comparative example and Example 1 is that the copper plating additives include a polydisulfide sodium dipropane sulfonate 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.

[0086] Comparative Example 5

[0087] The difference between this comparative example and Example 1 is that the copper plating additives include a polydisulfide sodium dipropane sulfonate 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.

[0088] Application Examples 1 to 9 and Comparative Application Examples 1 to 5

[0089] The copper plating solutions provided in Examples 1 to 9 and Comparative Examples 1 to 5 were used to prepare a composite current collector, and the preparation method is as follows:

[0090] 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 cleaned and dried to obtain a composite current collector with a thickness of 6.5 μm.

[0091] Test conditions

[0092] 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:

[0093] ①Appearance inspection

[0094] Appearance inspection is the most basic and most commonly used inspection method. The appearance of the coating is required to be uniform, smooth, free of oxidative discoloration, grease, corrosion, scorch, dendritic and spongy cones, and the parts that are required to be coated are not coated. The present invention uses the visual brightness experience evaluation method to detect the appearance of the coating. The grading reference standards of the visual brightness experience evaluation method are as follows:

[0095] a. Grade 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;

[0096] b. The surface of the secondary (luminous) coating is bright, and the facial features and face can be seen, but the picture is blurry;

[0097] c. Level 3 (semi-bright) coating is slightly bright, and only the outline of the facial features can be seen;

[0098] d. Level 4 (matte) The surface of the coating is basically matte and the facial image cannot be seen.

[0099] The appearance inspection adopts the Hull cell experiment: the prepared composite copper plating additive is added into the copper foil electrolyte at an addition amount of 1 ml / L. The parameters of the copper foil electrolyte are 120 g / L copper sulfate, 120 g / L sulfuric acid, 60 mg / L chloride ion, and the current density is 3 ASD. The prepared Hull cell sheet is analyzed.

[0100] ②Deposition speed test

[0101] Use an electronic analytical balance to weigh the weight of the test piece substrate before the Hull cell experiment and record it as m1, then weigh the weight of the test piece obtained after chemical copper plating and record it as m2. Calculate the deposition rate according to the following formula:

[0102] v = (m2-m1) / (ρ·s·t);

[0103] Where: v is the deposition rate, ×10 -4 cm / h; ρ is the density of the substrate before chemical copper plating, g / cm 3 ; s is chemical

[0104] Area of ​​the test piece substrate before copper plating, cm 2 ; t is the chemical copper plating time, h.

[0105] ③Density test

[0106] The surface state of the composite current collector membrane was observed using a metallographic microscope.

[0107] 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 is bonded to a 1 mm thick aluminum foil, the composite current collector is bonded on top of the double-sided tape, and a layer of ethylene acrylic acid copolymer film (DuPont Nurcel0903, 50 μm thick) is covered on top of the composite current collector, and then the adhesion is tested at 1.3×105 N / m 2 , hot press at 120℃ for 10s, cool to room temperature, and cut into 150mm×15mm strips. Finally, fix the ethylene acrylic acid copolymer film of the sample strip to the upper fixture of the tensile machine, and the rest to the lower fixture. After fixation, the two are peeled at an angle of 180° and a speed of 100mm / min to test the peeling force, that is, the bonding force between the base layer and the metal layer.

[0108] ⑤ Composite current collector tensile strength: The test refers to the national standard GB / T 1040.3-2006.

[0109] The test results are shown in Table 1:

[0110] Table 1

[0111]

[0112]

[0113] 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 adjusted to be the preferred component types, the composite current collector provided by Application Example 4 has the best performance.

[0114] At the same time, the effects of the brightener sodium 3-mercapto-1-propane sulfonate and sodium polydisulfide propane sulfonate are similar, while Application Example 6 shows that the effect of the leveling agent sodium polyethyleneimine alkyl (PN) is better than that of polyethyleneimine alkyl compound (GISS). When PN is used as a leveling agent, although a good degree of brightness can be obtained, the elongation is relatively poor. It can be seen from Application Example 5 that when the solvent used is ethanol, the appearance of the coating is poor, and the elongation and adhesion of the coating are also relatively poor, indicating that in this formula, ethanol as a solvent is not conducive to the performance of the coating.

[0115] Combining Application Examples 2 and 7, it can be seen that the effect of using ethylene thiourea alone as a leveling agent is relatively poor. When using ethylene thiourea as a leveling agent in combination with 2-mercaptobenzimidazole, a relatively good effect can be obtained. From Application Example 8, it can be seen that the effect of the leveling agent on the coating performance is not a simple superposition effect. Unreasonable increase in the dosage of the agent will make the coating performance worse. Application Example 9 shows that the optimal ratio of brightener, wetting agent and leveling agent is 1:2:4.

[0116] It can be seen from comparative application examples 1-3 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.

[0117] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A copper plating solution, characterized in that The copper plating solution comprises 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, characterized in that 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; Preferably, the copper plating additive comprises 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, characterized in that: The brightener comprises 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, preferably sodium polydisulfide propane sulfonate; Preferably, the wetting agent comprises 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, preferably EO-PO block copolymer; Preferably, the leveler comprises 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, preferably polyvinylamine alkylamine and / or polyethyleneimine alkyl salt.

4. A metal copper layer, characterized in that: The metallic copper layer is prepared by the copper plating solution according to any one of claims 1-3.

5. The metal copper layer according to claim 4, characterized in that: The thickness of the metal copper layer is 1-3 μm, preferably 1 μm.

6. A process for preparing the metal copper layer according to claim 4 or 5, characterized in that: The process comprises 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, characterized in that The chemical deposition method includes direct current plating or pulse plating.

8. A composite current collector, characterized in that: The composite current collector 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 according to claim 4 or 5.

9. The composite current collector according to claim 8, characterized in that: The base layer is a polymer layer; Preferably, the thickness of the base layer is 1-10 μm, preferably 4.5 μm; Preferably, the thickness of the metal conductive layer is 400-1500 nm; Preferably, the thickness of the protective layer is 20-80 nm.

10. A secondary battery, characterized in that: The secondary battery comprises a positive electrode, a negative electrode, an electrolyte and a separator. The negative electrode comprises a current collector and a negative electrode active material layer arranged on at least one side of the current collector. The current collector is the composite current collector according to claim 8 or 9.

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