CN116590762A

CN116590762A - Electrolyte additive for electrolytic copper foil, high-resistance high-ductility electrolytic copper foil and production method thereof

Info

Publication number: CN116590762A
Application number: CN202310644370.8A
Authority: CN
Inventors: 杨帅国; 文敏; 江泱; 董朝龙; 何博通
Original assignee: Jiujiang Defu Technology Co Ltd
Current assignee: Jiujiang Defu Technology Co Ltd
Priority date: 2023-06-01
Filing date: 2023-06-01
Publication date: 2023-08-15
Also published as: WO2024244098A1

Abstract

The application discloses an electrolyte additive for electrolytic copper foil, high-resistance high-ductility electrolytic copper foil and a production method thereof. An electrolyte additive for electrolytic copper foil, comprising, in parts by weight: 15-60 parts of organic divalent sulfide, 10-40 parts of collagen, 5-45 parts of brightening agent with sulfur-containing heterocyclic structure, 10-70 parts of nitrogenous polymer leveling agent, 15-40 parts of chloride ion and 20-90 parts of ether compound. The additive disclosed by the application not only adopts organic divalent sulfide as a brightening agent, but also adopts a brightening agent containing a sulfur heterocyclic structure, and the brightening agent containing the sulfur heterocyclic structure is matched with a nitrogenous polymer leveling agent in a synergistic manner, so that a copper foil with extremely high tensile strength can be obtained, the elongation of the copper foil is effectively improved, and meanwhile, the surface stability of the copper foil is excellent.

Description

Electrolyte additive for electrolytic copper foil, high-resistance high-ductility electrolytic copper foil and production method thereof

Technical Field

The application relates to the field of copper foil, in particular to an electrolyte additive for electrolytic copper foil, high-resistance high-ductility electrolytic copper foil and a production method thereof.

Background

As the thickness of the lithium-ion battery copper foil is reduced, the mechanical properties of the copper foil are also greatly changed, and most remarkable is the reduction of tensile strength and elongation percentage, which directly affect the production efficiency of lithium-ion battery manufacturing and the safety of the lithium-ion battery.

Coating and wrinkling. Coating is an important production link of a downstream battery client of a copper foil, and coating refers to coating a negative electrode material on the copper foil, if the tensile strength of the copper foil is low, the copper foil is wrinkled or broken in the coating process, a client production line needs to clean and finish a coating machine with a length of tens of meters at a high temperature, and then the copper foil is pulled again and coated, so that the production efficiency of the lithium battery client is seriously affected.

The battery swells. In the charge and discharge process of the lithium battery, due to the silicon-containing materials and the like in the anode material, the materials can generate certain expansion in the charge and discharge process, and the copper foil serves as an anode current collector to play roles of bearing the anode material and serving as a current conductor. If the copper foil has low elongation, the battery is easy to break in the expansion process, the service life of the lithium battery is shortened, and the safety of the battery is influenced. Therefore, it is required to maintain a high elongation while ensuring the tensile strength of the copper foil.

The use of the electrolyte additive is a key influencing factor for preparing the copper foil, and the general copper foil additive formula comprises three parts, namely a brightening agent, a leveling agent and a positioning agent, which act synergistically to promote the copper foil to have an excellent composition structure and obtain excellent mechanical properties. The brightening agent can effectively promote the nucleation of crystal grains, generate the effect of refining the crystal grains, and achieve the effect of brightening the rough surface, and is mostly some sulfur-containing organic compounds; the leveling agent can promote the grain center growth of the copper foil, and most of the leveling agent is protein with different molecular weights; the plating solution can be used for effectively improving the dispersion capacity of the plating solution, and promoting other additives to quickly, effectively and uniformly act on the polyether substances in the copper plating process.

Disclosure of Invention

The application aims to provide an electrolyte additive for electrolytic copper foil, high-resistance high-elongation electrolytic copper foil and a production method thereof, which are used for solving the problems of coating wrinkling and expansion fracture in the use process of the conventional copper foil in the manufacturing process of a lithium ion battery.

The first aspect of the present application provides an electrolyte additive for electrolytic copper foil, comprising, in parts by weight: 15-60 parts of organic divalent sulfide, 10-40 parts of collagen, 5-45 parts of brightening agent with sulfur-containing heterocyclic structure, 10-70 parts of nitrogenous polymer leveling agent, 15-40 parts of chloride ion and 20-90 parts of ether compound.

Further, the organic divalent sulfide includes one or more selected from the group consisting of disodium 3,3' -dithiobis-1-propanesulfonate, sodium 3-mercaptopropane sulfonate, and mercaptobenzimidazole.

Further, the weight average molecular weight of the collagen is 3000-6000.

Further, the brightening agent having a sulfur-containing heterocyclic structure includes one or more selected from the group consisting of thiazolidinethione, diphenylvinylpyridine and 2-hydroxyphenylthiourea.

Further, the nitrogen-containing polymer leveling agent includes a polyethyleneimine compound, and preferably the nitrogen-containing polymer leveling agent includes one or more selected from the group consisting of a polyethyleneimine alkyl compound, a polyethyleneimine alkane, and an ethoxypolyethyleneimine.

Further, the ether compound includes crown ether compounds, and preferably the ether compound includes one or more selected from the group consisting of 9-crown-3, 12-crown-4, 15-crown-5, 18-crown-6, benzo-12-crown-4, benzo-15-crown-5, benzo-18-crown-6, and benzo-21-crown-7.

Further, the electrolyte additive includes, in parts by weight: 40-45 parts of organic divalent sulfide, 20-35 parts of collagen, 30-45 parts of thiazolidinethione, 35-50 parts of polyethyleneimine compound, 20-30 parts of chloride ion and 60-70 parts of crown ether compound, wherein the organic divalent sulfide comprises 3,3' -dithiobis-1-propanesulfonic acid disodium salt or 3-mercaptopropane sulfonic acid sodium salt.

In a second aspect of the present application, there is provided a method for producing an electrolytic copper foil, comprising the steps of: (1) Dissolving elemental copper metal in an electrolyte, wherein the electrolyte comprises sulfuric acid-copper sulfate solution and an additive, and the additive is any electrolyte additive; (2) carrying out electrolytic treatment on the metal simple substance copper to obtain an original foil; and (3) washing and passivating the original foil to obtain the copper foil.

Further, the concentration of copper ions in the electrolyte is 75g/L to 100g/L, and/or the concentration of sulfuric acid is 90g/L to 140g/L.

Further, the content of the organic divalent sulfide in the electrolyte is 15mg/L-60mg/L; the content of the collagen in the electrolyte is 10mg/L-40mg/L; the content of the thiazolidinethione in the electrolyte is 5mg/L-45mg/L; the content of the nitrogen-containing polymer leveling agent in the electrolyte is 10mg/L-70mg/L; the content of the ether compound in the electrolyte is 20mg/L-90mg/L; the content of chloride ions in the electrolyte is 15-40ppm.

Further, the above electrolysis conditions are selected from any one or more of the following: the temperature of electrolysis is 40-60 ℃, and the flow rate of the electrolyte is 40m ³ /h-50m ³ And/h, the current density of the electrolysis is 6000A/m ² -7000A/m ² 。

In a third aspect of the present application, there is provided an electrolytic copper foil satisfying at least two of the following conditions: the tensile strength is between 480MPa and 550MPa, the elongation is 6 to 8, the grain size is 0.4 mu m to 0.5 mu m, and the twin crystal proportion is 52 percent to 70 percent.

In a fourth aspect of the present application, there is provided an electrolytic copper foil obtained by the production method of any one of the above.

The additive disclosed by the application not only adopts organic divalent sulfide as a brightening agent, but also adopts a brightening agent containing a sulfur heterocyclic structure, and the brightening agent containing the sulfur heterocyclic structure is matched with a nitrogenous polymer leveling agent in a synergistic manner, so that a copper foil with extremely high tensile strength can be obtained, the elongation of the copper foil is effectively improved, and meanwhile, the surface stability of the copper foil is excellent.

Drawings

In order to more clearly illustrate the embodiments of the present application, the drawings that are used in the description of the embodiments will be briefly described below.

FIG. 1 is an EBSD photograph of the thickness of copper foil prepared using example 3.

FIG. 2 is an EBSD photograph of the thickness of copper foil prepared using comparative example 2.

Fig. 3 is a TEM photograph of the copper foil prepared using example 3.

Remarks: the application relates to a double-light copper foil M (rough) surface and an S (light) surface, wherein the S surface is the surface which is attached to a cathode roller, and the other surface is the M surface.

Detailed Description

The present application will be described in further detail below in order to make the explanation of the present application more clearly apparent. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the application, fall within the scope of protection of the application.

The first embodiment of the present application provides an electrolyte additive for electrolytic copper foil, comprising, in parts by weight: 15-60 parts of organic divalent sulfide, 10-40 parts of collagen, 5-45 parts of brightening agent with sulfur-containing heterocyclic structure, 10-70 parts of nitrogenous polymer leveling agent, 15-40 parts of chloride ion and 20-90 parts of ether compound.

The brightening agent containing sulfur heterocyclic structures, collagen and the nitrogenous polymer leveling agent are matched with the weight portions, so that the crystal structure of the copper foil is smoother and denser, a large number of nanocrystalline areas are generated, the fine crystal strengthening effect is enhanced, meanwhile, the large number of twin crystals in the copper foil are promoted, and the generation probability and proportion of the nanometer twin crystals are greatly improved under the synergistic effect. The excellent structural interaction of fine crystals and nano twin crystals improves the tensile strength of the copper foil and the elongation at the same time.

In a word, the application uses the theory principle of grain refinement and improving the nano twin crystal proportion, breaks through the limitation of the traditional formula, innovatively adopts specific additives and optimized proportions to reduce the introduction of impurities, on one hand, generates a large number of nano crystal regions, simultaneously improves the twin crystal proportion of the copper foil and generates an obvious nano twin crystal structure, ensures the tensile strength of the copper foil, simultaneously maintains higher elongation, and further effectively solves the problems of coating wrinkling and expansion fracture of the traditional copper foil in the manufacturing process of the lithium ion battery.

The organic divalent sulfide forms a cuprous complex with the surface of the copper foil in the electroplating process and is adsorbed on a copper deposition site to play a role in catalysis and promote deposition, so that the roughness of the copper foil can be reduced within a certain concentration, and the tensile strength and the elongation of the copper foil are obviously improved. The organic divalent sulfide used in the present application may be selected from among commonly used sulfur-containing organic compounds as a brightening agent, including, but not limited to, sodium polydithio-dipropyl sulfonate, sodium 4- [ [2- (acetamido) ethyl ] dithio ] -1-butanesulfonate, thiamine disulfide, 2-substituted hydrazono-1, 3-dithiolane, ethylenethiourea, 3' -dithiobis-1-propanesulfonic acid disodium salt, 3-mercaptopropane sulfonic acid sodium salt, mercaptobenzimidazole. The sulfhydryl and sulfonate can be combined with metal ions to generate complex, so that the reducibility of the metal ions is accelerated, in addition, the sulfhydryl has the functions of enhancing the toughness of a coating, reducing the liquid level tension and improving the coating property and oxidation resistance. In some embodiments, the organic divalent sulfide includes one or more selected from the group consisting of disodium 3,3' -dithiobis-1-propanesulfonate, sodium 3-mercaptopropane sulfonate, mercaptobenzimidazole. The above-mentioned organic divalent sulfide is present not only in the form of a complex with copper ions during the plating process, but also can cover the surface of copper ions and promote their reduction and deposition, eventually forming a dense and uniformly distributed plating layer. At the same time, these compounds have the following advantages:

1. physical properties of the plating solution, such as surface tension and viscosity, can be better controlled, so that uniformity and coordination of the plating solution are improved, and quality of the plating coating is further improved.

2. Improving the electroplating efficiency of the plating solution: the electrochemical reaction can be effectively promoted, the electrode reaction efficiency and reaction rate are improved, and the electroplating time is shortened, so that the production efficiency is improved. Meanwhile, the additives also have the effects of reducing side reactions and improving the use efficiency of copper ions, so that the potential range of the battery is reduced, the electric energy is saved, and the production cost is reduced.

3. Improving the adhesive force of the electroplating coating: the additives are used as a surfactant in the electroplating solution, and can reduce the surface tension and interfacial energy of the liquid, so that the interaction force between the electroplating solution and the substrate is facilitated, and the adhesive force of the coating is improved. In addition, the compounds can control oxidation-reduction potential in the electroplating process, so that defects on the surface of the electrode are filled, and the adhesiveness and stability of the plating layer are further enhanced.

4. The environment-friendly performance is achieved: the use amount is small in the electroplating process, and the influence of the electroplating liquid on the environment is reduced. In addition, the additives can be combined with copper ions to form stable complex in the electroplating process, so that the concentration of copper ions in the electroplating solution is reduced, the generation of pollutants is reduced, and the environment-friendly requirement is met.

5. Has the economy: the additives are less in dosage in the electroplating process and low in cost, and can effectively improve the electroplating rate and ensure that the electroplated coating is more uniformly distributed, thereby saving materials and energy sources, reducing the production cost and improving the production efficiency. In addition, the quality and the adhesive force of the electroplating coating can be improved, the residual quantity and the rejection rate are reduced, and the economic benefit of production is further improved.

The collagen used in the present application is a conventional commercial collagen, and in order to improve dispersibility of the collagen in an electrolyte, in some embodiments, the weight average molecular weight of the collagen is selected to be 3000 to 6000.

The brightening agent for the sulfur-containing heterocyclic structure of the present application may be selected from conventional such brightening agents, and in some embodiments the brightening agent for the sulfur-containing heterocyclic structure comprises one or more selected from the group consisting of thiazolidinethione, diphenylvinylpyridine and 2-hydroxy phenylthiourea. Especially, the synergistic effect of the thiazolidine thioketone and the nitrogenous polymer leveling agent is better, the tensile strength (more than 700 MPa) of the copper foil can be further improved, the elongation of the copper foil is more effectively improved, and meanwhile, the surface stability of the copper foil is excellent.

The cation of the nitrogen-containing polymer leveling agent is easy to adsorb on an active site, unsaturated bonds enhance adsorption, and under the condition of electroplating convection, the microscopic profile fluctuation of the surface is reduced, the surface roughness is reduced, and the tensile strength and the elongation of the copper foil are obviously improved. To further enhance the above-described effect of the nitrogen-containing polymeric leveling agent, in some embodiments, the nitrogen-containing polymeric leveling agent comprises a polyethyleneimine compound, preferably the nitrogen-containing polymeric leveling agent comprises one or more selected from the group consisting of a polyethyleneimine alkyl compound, a polyethyleneimine alkane, or an ethoxypolyethyleneimine. The application has no special requirement on the molecular weight of the nitrogen-containing polymer leveling agent.

The ether compound is used as a plating aid, is favorable for uniform copper plating, and can be conventional ether polymers and crown ether compounds. The crown ether compound molecules have uncharged annular structures, so that the crown ether compound molecules have good nonionic property in the electroplating process, the resistivity and the liquid level tension of the electroplating solution can be further reduced, and the reduction of metal ions is promoted; when crown ether compounds interact with ions, multi-layer coordination action often occurs, and more stable complex compounds than other ether polymers can be formed, so that the catalytic performance of the electroplating solution is improved more effectively; the crown ether compound has better water solubility than other ether polymers, is easy to dissolve in water to form stable electroplating solution, and has no pollution to the environment in the electroplating process; the crown ether compound can form complex with metal ion more effectively, can deposit on the metal surface more effectively in the electroplating process, and form uniform and compact metal coating. Therefore, the crown ether compound has the advantages of good nonionic property, strong multilayer coordination effect, good water solubility, strong film forming capability and the like in electroplating, and can further improve the electrochemical performance of the electroplating solution to obtain a high-quality metal coating. In some embodiments, the ether compound includes a crown ether compound, preferably the ether compound includes one or more selected from the group consisting of 9-crown-3, 12-crown-4, 15-crown-5, 18-crown-6, benzo-12-crown-4, benzo-15-crown-5, benzo-18-crown-6, and benzo-21-crown-7.

In some embodiments, the chloride ion is derived from hydrochloric acid or a chloride salt, preferably sodium chloride or potassium chloride, preferably hydrochloric acid is used to provide the chloride ion. The chloride ion is an anode activator and a stress relieving agent of the coating, can help the anode to dissolve, and can be synergistic with the additive to lead the coating to be bright and smooth, and can reduce the tensile stress of the coating.

In some embodiments, the parts by weight of the organic divalent sulfide include, but are not limited to, 15, parts, 20, 25, 30, 35, 40, 45, 55, or 60 parts.

In some embodiments, collagen includes, but is not limited to, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, or 40 parts.

In some embodiments, the sulfur-containing heterocyclic structured brightening agent includes, but is not limited to, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or 45 parts.

In some embodiments, the nitrogen-containing polymeric leveling agent includes, but is not limited to, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 55 parts, 60 parts, 65 parts, or 70 parts.

In some embodiments, chloride ions include, but are not limited to, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, or 40 parts.

In some embodiments, the ether compound includes, but is not limited to, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, or 90 parts.

In some embodiments, the electrolyte additive includes, in parts by weight: 40-45 parts of organic divalent sulfide, 20-35 parts of collagen, 30-45 parts of thiazolidinethione, 35-50 parts of polyethyleneimine compound, 20-30 parts of chloride ion and 60-70 parts of crown ether compound, wherein the organic divalent sulfide comprises 3,3' -dithiobis-1-propanesulfonic acid disodium salt or 3-mercaptopropane sulfonic acid sodium salt. The synergy of crown ether compounds and thiazolidine thioketone can obviously improve the speed and efficiency of electrochemical reaction and promote the reduction and uniform deposition of metal ions; the electrochemical property of the electroplating solution is improved, the stability of the electrochemical reaction is improved, and the mass transfer and diffusion of the solution are promoted; promoting the reduction of metal ions, and being beneficial to forming a uniform, compact and bright metal coating, thereby improving the performances of corrosion resistance, wear resistance, heat resistance and the like of the coating; compared with the traditional electroplating solution system, the synergistic effect of the crown ether compound and the thiazolidine thioketone can reduce the use amount of harmful substances, reduce carbon emission and is more environment-friendly. In conclusion, the synergistic effect of the crown ether compound and the thiazolidine thioketone can improve the electrochemical reaction efficiency, improve the electroplating solution system, improve the plating performance and realize the environment-friendly production.

The second embodiment of the application provides a production method of an electrolytic copper foil, which comprises the following steps: (1) Dissolving elemental copper metal in an electrolyte, wherein the electrolyte comprises sulfuric acid-copper sulfate solution and an additive, and the additive is any electrolyte additive; (2) carrying out electrolytic treatment on the metal simple substance copper to obtain an original foil; and (3) washing and passivating the original foil to obtain the copper foil.

The production method adopts the specific additive, so that a large number of nanocrystalline regions are generated during electrolysis, the twin crystal proportion of the copper foil is improved, an obvious nano twin crystal structure is generated, the tensile strength of the copper foil is ensured, and meanwhile, the higher elongation is kept.

In some embodiments of the application, the concentration of copper ions in the electrolyte is 75g/L to 100g/L and/or the concentration of sulfuric acid is 90g/L to 140g/L. To improve the stability of electrolysis.

In some embodiments of the application, the content of the organic divalent sulfide in the electrolyte is 15mg/L to 60mg/L; the content of the collagen in the electrolyte is 10mg/L-40mg/L; the content of the thiazolidinethione in the electrolyte is 5mg/L-45mg/L; the content of the nitrogen-containing polymer leveling agent in the electrolyte is 15mg/L-70mg/L; the content of the ether compound in the electrolyte is 20mg/L-90mg/L; the content of chloride ions in the electrolyte is 10-40ppm. By controlling the content of each component in the electrolyte in the above range in the electrolytic process, the full synergistic effect of each component is realized, and the tensile strength and the elongation of the copper foil are better improved at the same time.

The electrolytic conditions of the application can be referred to conventional copper foil electrolytic conditions, that is, the use of the electrolyte additive of the application does not need to change the conventional electrolytic conditions, so the applicability is wider. In some embodiments, the conditions of electrolysis are selected from any one or more of the following: the temperature of electrolysis is 40-60 ℃, and the flow rate of the electrolyte is 40m ³ /h-50m ³ And/h, the current density of the electrolysis is 6000A/m ² -7000A/m ² . So as to promote the full play of the function of electrolyte additives.

The washing and passivation after the electrolysis can be carried out by referring to the washing process and passivation process commonly used in the electrolytic copper foil, and the application is not repeated.

A third embodiment of the present application provides an electrolytic copper foil satisfying at least two of the following conditions: the tensile strength is between 480MPa and 550MPa, the elongation is 6 to 8, the grain size is 0.4 mu m to 0.5 mu m, and the twin crystal proportion is 52 percent to 70 percent. The electrolytic copper foil has higher tensile strength and higher elongation at the same time, thereby effectively solving the problems of coating wrinkling and expansion fracture in the use process of the traditional copper foil in the manufacturing process of the lithium ion battery.

The tensile strength and the elongation were obtained by testing copper foil at room temperature (about 25 ℃) according to test method GB/T29847-2013 using an HY-0230 universal material tester manufactured by Shanghai scale wing precision instruments Co., ltd.

A fourth embodiment of the present application provides an electrolytic copper foil obtained by using any one of the production methods described above. The electrolytic copper foil obtained by the production method has higher tensile strength and higher elongation at the same time, thereby effectively solving the problems of coating wrinkling and expansion fracture in the use process of the existing copper foil in the manufacturing process of the lithium ion battery.

The advantageous effects of the present application will be further described below with reference to examples and comparative examples. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

Dissolving metal simple substance copper metal in sulfuric acid to prepare sulfuric acid-copper sulfate solution as electrolyte, and adding an additive into the sulfuric acid-copper sulfate solution; the concentration of copper ions in the obtained electrolyte is 86g/L, the concentration of sulfuric acid is 110g/L, the concentration of 3,3' -dithiobis-1-propanesulfonic acid disodium salt is 45mg/L, the concentration of collagen (molecular weight is 5000-6000) is 22mg/L, the concentration of thiazolidinethione is 45mg/L, the concentration of polyethyleneimine octadecyl urea (CAS number: 6844125-8) is 35mg/L, the concentration of 27-crown-9 and benzo-30-crown-10 is 60mg/L, and the concentration of chloride ions is 20ppm (chloride ions are provided by hydrochloric acid); the electrolysis temperature is 55 ℃, and the flow rate of the electrolyte is 45m ³ /h, electrolysis current density of 6500A/m ² And (3) washing, passivating and drying the obtained original foil through electrolytic reaction to obtain the uncut finished lithium electrodeposited copper foil.

Example 2

Dissolving metal simple substance copper metal in sulfuric acid to prepare sulfuric acid-copper sulfate solution serving as electrolyte, adding an additive into the sulfuric acid-copper sulfate solution, wherein the concentration of copper ions in the electrolyte is 89g/L, the concentration of sulfuric acid is 115g/L, the combined concentration of 3,3' -dithiobis-1-propanesulfonic acid disodium salt and 3-mercaptopropane sodium salt in a mass ratio of 1:1 is 40mg/L, the concentration of collagen (molecular weight is 5000-6000) is 25mg/L, the concentration of thiazolidinedione is 35mg/L, the concentration of ethoxypolyethylenimine (CAS number: 26658-46-8) is 35mg/L, the concentration of 12-crown-4 is 70mg/L, and the concentration of chloride ions is 22ppm (hydrochloric acid is adopted to provide chloride ions); the electrolysis temperature is 55 ℃, and the flow rate of the electrolyte is 45m ³ /h, electrolysis current density of 6500A/m ² Washing, passivating and drying the obtained raw foil through electrolytic reaction to obtain the uncut foilAnd (5) obtaining the finished lithium electric copper foil.

Example 3

Dissolving metal simple substance copper metal in sulfuric acid to prepare sulfuric acid-copper sulfate solution as electrolyte, and adding an additive into the sulfuric acid-copper sulfate solution; the concentration of copper ions in the obtained electrolyte is 90g/L, the concentration of sulfuric acid is 120g/L, the combined concentration of 3,3' -dithiobis-1-propanesulfonic acid disodium salt and 3-mercaptopropane sulfonic acid sodium salt in a mass ratio of 2:1 is 45mg/L, the concentration of collagen (molecular weight is 5000-6000) is 20mg/L, the concentration of thiazolidinethione is 30mg/L, the concentration of ethoxypolyethylenimine (CAS number: 26658-46-8) is 35mg/L, the concentration of 12-crown-4 is 60mg/L, and the concentration of chloride ions is 30ppm (hydrochloric acid is adopted to provide chloride ions); the electrolysis temperature is 55 ℃, and the flow rate of the electrolyte is 45m ³ And/h, the electrolysis current density is 7000A/m ² And (3) washing, passivating and drying the obtained original foil through electrolytic reaction to obtain the uncut finished lithium electrodeposited copper foil.

Example 4

Dissolving metal simple substance copper metal in sulfuric acid to prepare sulfuric acid-copper sulfate solution as electrolyte, and adding an additive into the sulfuric acid-copper sulfate solution; the concentration of copper ions in the obtained electrolyte is 100g/L, the concentration of sulfuric acid is 130g/L, the concentration of 3-mercaptopropane sulfonic acid sodium salt is 50mg/L, the concentration of collagen (molecular weight is 5000-6000) is 35mg/L, the concentration of tetrahydrothiazolethione is 38mg/L, the concentration of PVAM polyvinyl amine (CAS: 183815-54-5) is 35mg/L, the concentration of 18-crown-6 is 60mg/L, and the concentration of chloride ions is 30ppm (hydrochloric acid is adopted to provide chloride ions); the electrolysis temperature is 60 ℃, and the flow rate of the electrolyte is 45m ³ And/h, the electrolysis current density is 7000A/m ² And (3) washing, passivating and drying the obtained original foil through electrolytic reaction to obtain the uncut finished lithium electrodeposited copper foil.

Example 5

The only difference from example 3 was that the total concentration of disodium 3,3' -dithiobis-1-propanesulfonate and sodium 3-mercaptopropane sulfonate was 15mg/L, and the remainder was the same as in example 3.

Example 6

The only difference from example 3 was that the total concentration of disodium 3,3' -dithiobis-1-propanesulfonate and sodium 3-mercaptopropane sulfonate was 60mg/L, and the remainder was the same as in example 3.

Example 7

The procedure was repeated except that the concentration of collagen (molecular weight: 5000-6000) was 10mg/L, which was different from example 3, and the remainder was the same as in example 3.

Example 8

The procedure was repeated except that the concentration of collagen (molecular weight: 5000-6000) was 40mg/L, which was different from example 3, and the remainder was the same as in example 3.

Example 9

The procedure was repeated except that the concentration of collagen (molecular weight: 3000-4000) was 20mg/L, which was different from example 3, and the remainder was the same as in example 3.

Example 10

The procedure was as in example 3 except that the concentration of thiazolidinedione was 5mg/L, and the remainder was the same as in example 3.

Example 11

The procedure of example 3 was repeated except that the concentration of ethoxypolyethylenimine (CAS number 26658-46-8) was 10mg/L, and the remainder was the same as in example 3.

Example 12

The procedure was repeated except that the concentration of ethoxypolyethylenimine (CAS number 26658-46-8) was 70mg/L, as in example 3.

Example 13

The procedure was repeated except that the concentration of ethoxypolyethylenimine (CAS number: 26658-46-8) was 50mg/L, as in example 3.

Example 14

The procedure was repeated except that the chlorine ion concentration was 10ppm (hydrochloric acid was used to supply chlorine ions) as in example 3, and the procedure was repeated as in example 3.

Example 15

The procedure was repeated except that the chlorine ion concentration was 40ppm (chlorine ion was supplied with hydrochloric acid) as in example 3, and the procedure was repeated as in example 3.

Example 16

The procedure was repeated except that the concentration of 12-crown-4 was 20mg/L, which was different from example 3, and the remainder was the same as in example 3.

Example 17

The only difference from example 3 was that the 12-crown-4 concentration was 70mg/L, and the rest was the same as in example 3.

Example 18

The procedure was repeated except that the same concentration of 12-crown-4 was replaced with fatty alcohol-polyoxyethylene ether M (CAS: 37335-03-8) as in example 3, and the remainder was the same as in example 3.

Example 19

The difference from example 3 was that the copper ion concentration in the electrolytic solution was 65g/L, and the remainder was the same as in example 3.

Example 20

The difference from example 3 was that the sulfuric acid concentration was 90g/L, and the rest was the same as in example 3.

Example 21

The procedure was repeated except that the concentration of sulfuric acid was 140g/L in the same manner as in example 3.

Example 22

The difference from example 3 was that the electrolysis temperature was 40℃and the rest was the same as in example 3.

Example 23

The difference from example 3 is that the electrolyte feed flow rate was 40m ³ And/h, the remainder being the same as in example 3.

Example 24

The difference from example 3 is that the electrolyte feed flow rate was 50m ³ And/h, the remainder being the same as in example 3.

Example 25

The difference from example 3 is only that the electrolysis current density is 6000A/m ² The remainder was the same as in example 3.

Example 26

As in example 1, the current density in the electrolyte was 7000A/m ² 。

Comparative example 1

The procedure of example 1 was repeated except that 3,3' -dithiobis-1-propanesulfonic acid disodium salt was not added to the electrolyte.

Comparative example 2

As in example 3, except that 12-crown-4 was not added to the electrolyte.

Comparative example 3

In the same manner as in example 3, except that 3,3' -dithiobis-1-propanesulfonic acid disodium salt and 3-mercaptopropane sulfonic acid sodium salt were not added to the electrolyte.

Comparative example 4

The only difference from example 3 was that the total concentration of disodium 3,3' -dithiobis-1-propanesulfonate and sodium 3-mercaptopropane sulfonate was 10mg/L, and the remainder was the same as in example 3.

Comparative example 5

The only difference from example 3 was that the total concentration of disodium 3,3' -dithiobis-1-propanesulfonate and sodium 3-mercaptopropane sulfonate was 70mg/L, and the remainder was the same as in example 3.

Comparative example 6

The procedure was as in example 3, except that no thiazolidinedione was added, and the remainder was the same as in example 3.

Comparative example 7

The procedure was as in example 3 except that the concentration of thiazolidinedione was 50mg/L, and the remainder was the same as in example 3.

Comparative example 8

The procedure of example 3 was repeated except that no ethoxypolyethylenimine (CAS number 26658-46-8) was added and the remainder was the same as in example 3.

Comparative example 9

The procedure was repeated except that the concentration of ethoxypolyethylenimine (CAS number 26658-46-8) was 80mg/L, as in example 3.

Comparative example 10

The only difference from example 3 was that the concentration of 12-crown-4 was 100mg/L, and the remainder was the same as in example 3.

In the above examples and comparative examples, the respective parameters were controlled to the corresponding set values as much as possible, but as the reaction proceeds, the respective concentration and electrical performance parameters were fluctuated within practically allowable ranges.

The electrodeposited copper foils prepared in examples 1 to 26 and comparative examples 1 to 10 were tested for microstructure and basic physical properties as follows:

back Scattering Diffraction (EBSD) test: the microstructure of the copper foil portion samples of each example and comparative example was observed using a C-Swift EBSD detector manufactured by oxford instrument, england. The EBSD maps of example 3 and comparative example 2 are shown in fig. 1 to 2, fig. 1 having a large number of nanocrystalline regions and twin regions, fig. 2 having a large overall grain size, with only a small number of nanocrystalline regions and fewer twin regions; the TEM image of example 3 is shown in fig. 3, with a pronounced nano-sized twin structure.

Gloss test: according to the test method GB/T13891, the gloss of the M surface of the copper foil in the longitudinal direction is measured under the condition of 60 degrees of light incidence angle by using a WGG60-E gloss meter manufactured by Keshida photoelectric instruments Co.

Tensile strength and elongation test: according to the test method GB/T29847-2013, the tensile strength and the elongation of the copper foil are tested at room temperature (about 25 ℃) by using an HY-0230 universal material testing machine manufactured by Shanghai scale wing precision instruments Co.

The microstructure and basic physical properties of the electrodeposited copper foil prepared in each example and each comparative example are shown in Table 1.

TABLE 1 results of Performance test of electrolytic copper foil

In conclusion, the reasonable additive formula and proportion can effectively control the crystal grain growth mode of the copper foil in the electroplating process, generate a large number of nanocrystals and nanometer twin crystals, and maintain good plasticity while enhancing the tensile strength of the copper foil. The strength and toughness of the copper foil can be effectively improved by controlling the grain size and forming nano twin crystals. When the grain size becomes smaller to a certain extent, the interface energy occupies larger and larger proportion of the whole material volume, the volume density between grains is larger and larger, the density of grain boundary is increased, the diffusion distance is shortened, dislocation is easily blocked by the grain boundary, and the plastic deformation is blocked. The existence of the nanometer twin crystal interface makes the material not easy to break, thereby supporting plastic deformation under high strain rate. The dispersion stress field applied by the nano twin crystal interface can also block the action of matrix atoms, thereby improving the strength and toughness. At this time, the bending and twisting of the grain boundaries helps to limit the relative displacement between the grains, improve the ductility of the material, and exert a mechanical strengthening effect.

While the application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the application. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

1. An electrolyte additive for electrolytic copper foil, characterized in that the electrolyte additive comprises, in parts by weight:

15-60 parts of organic divalent sulfide, 10-40 parts of collagen, 5-45 parts of brightening agent with sulfur-containing heterocyclic structure, 10-70 parts of nitrogenous polymer leveling agent, 15-40 parts of chloride ion and 20-90 parts of ether compound.

2. The electrolyte additive of claim 1, wherein the organic divalent sulfide comprises one or more selected from the group consisting of disodium 3,3' -dithiobis-1-propanesulfonate, sodium 3-mercaptopropane sulfonate, mercaptobenzimidazole.

3. Electrolyte additive according to claim 1 or 2, wherein the collagen has a weight average molecular weight of 3000-6000.

4. The electrolyte additive according to any one of claims 1 to 3, wherein the brightening agent having a sulfur-containing heterocyclic structure comprises one or more selected from the group consisting of thiazolidinethione, diphenylvinylpyridine and 2-hydroxy phenylthiourea.

5. The electrolyte additive according to any one of claims 1 to 4, wherein the nitrogen-containing polymeric leveling agent comprises a polyethylenimine compound, preferably the nitrogen-containing polymeric leveling agent comprises one or more selected from the group consisting of polyethylenimine alkyl compounds, polyethylenimine or ethoxypolyethylenimine.

6. The electrolyte additive according to any one of claims 1 to 5, wherein the ether compound comprises a crown ether compound, preferably the ether compound comprises one or more selected from the group consisting of 9-crown-3, 12-crown-4, 15-crown-5, 18-crown-6, benzo-12-crown-4, benzo-15-crown-5, benzo-18-crown-6, benzo-21-crown-7.

7. The electrolyte additive according to any one of claims 1 to 6, characterized in that the electrolyte additive comprises, in parts by weight:

40-45 parts of organic divalent sulfide, 20-35 parts of collagen, 30-45 parts of thiazolidinethione, 35-50 parts of polyethyleneimine compound, 20-30 parts of chloride ion and 60-70 parts of crown ether compound, wherein the organic divalent sulfide comprises 3,3' -dithiobis-1-propanesulfonic acid disodium salt or 3-mercaptopropane sulfonic acid sodium salt.

8. The production method of the electrolytic copper foil is characterized by comprising the following steps:

(1) Dissolving elemental copper metal in an electrolyte comprising a sulfuric acid-copper sulfate solution and an additive that is the electrolyte additive of any one of claims 1 to 7;

(2) Carrying out electrolytic treatment on the metal elemental copper to obtain an original foil;

(3) And washing and passivating the original foil to obtain the copper foil.

9. The production method according to claim 8, wherein the concentration of copper ions in the electrolyte is 75g/L to 100g/L, and/or the concentration of sulfuric acid is 90g/L to 140g/L.

10. The production method according to claim 8 or 9, wherein the content of the organic divalent sulfide in the electrolytic solution is 15mg/L to 60mg/L; the content of the collagen in the electrolyte is 10mg/L-40mg/L; the content of the thiazolidinethione in the electrolyte is 5mg/L-45mg/L; the content of the nitrogen-containing polymer leveling agent in the electrolyte is 10mg/L-70mg/L; the content of the ether compound in the electrolyte is 20mg/L-90mg/L; the content of the chloride ions in the electrolyte is 15-40ppm.

11. The production method according to any one of claims 8 to 10, wherein the conditions of electrolysis are selected from any one or more of the following:

the temperature of electrolysis is 40-60 ℃, and the flow rate of the electrolyte is 40m ³ /h-50m ³ And/h, the current density of the electrolysis is 6000A/m ² -7000A/m ² 。

12. An electrolytic copper foil characterized in that the electrolytic copper foil satisfies at least two of the following conditions:

the tensile strength is between 480MPa and 550MPa, the elongation is 6 to 8, the grain size is 0.4 mu m to 0.5 mu m, and the twin crystal proportion is 52 percent to 70 percent.

13. An electrolytic copper foil, characterized in that it is obtained by the production method according to any one of claims 8 to 11.