Electrolyte for preparing copper foil with high tensile strength, copper foil and preparation method of copper foil

Abstract

The invention provides an electrolyte for preparing a copper foil with high tensile strength, the copper foil and a preparation method of the copper foil, the electrolyte comprises a main electrolyte and an additive, the main electrolyte comprises copper sulfate, sulfuric acid and chloride ions, the additive is prepared from industrial collagen, sodium dimethylformamide propane sulfonate, thiazolidinethione, fatty amine polyoxyethylene ether and hydroxypropyl methyl cellulose. According to the system, an industrial collagen and thiazolidinethione synergistic film forming mechanism is adopted, abnormal growth of copper grains is effectively inhibited, and the toughness and tensile strength of the material are enhanced; sodium dimethylformamide propane sulfonate is used as an efficient brightener to optimize a deposition microstructure and reduce grain boundary defects; hydroxypropyl methyl cellulose and fatty amine polyoxyethylene ether cooperatively regulate and control an electrolyte flow field, concentration polarization is reduced, and deposition uniformity is ensured; meanwhile, chloride ions and the thioketone additive form a stable coordination system, so that the deposition compactness is improved, and stress concentration is avoided.

Description

Technical Field

[0001] This invention relates to the field of copper foil preparation technology, and in particular to an electrolyte for preparing high tensile strength copper foil, copper foil, and a method for preparing the same. Background Technology

[0002] As a core material for the negative electrode current collector in lithium-ion batteries, copper foil has mechanical properties (tensile strength, elongation) that directly affect the battery's energy density, cycle life, and safety.

[0003] In existing technologies, a series of internal reactions occur during the charging and discharging process of lithium batteries, which causes the copper foil of the lithium battery to repeatedly expand and contract. If the tensile strength of the copper foil does not meet the target requirements, it cannot withstand greater mechanical stress, thus reducing the safety of the lithium battery. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an electrolyte for preparing high tensile strength copper foil, copper foil and preparation method thereof, aiming to solve the technical problem of safety issues such as breakage caused by external force when the tensile strength of copper foil does not meet the target requirements in the prior art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides: an electrolyte for preparing high-tensile copper foil, comprising a main electrolyte and additives, wherein the main electrolyte comprises copper sulfate, sulfuric acid and chloride ions, and the additives comprise industrial collagen at a concentration of 5-15 g / L, sodium dimethylformamide propane sulfonate at a concentration of 4-10 g / L, tetrahydrothiazolyl thione at a concentration of 1.5-3 g / L, fatty amine polyoxyethylene ether at a concentration of 20-40 mg / L, and hydroxypropyl methylcellulose at a concentration of 80-120 mg / L.

[0006] According to one aspect of the above technical solution, the concentration of the industrial collagen is 8-12 g / L, the concentration of the sodium dimethylformamide propane sulfonate is 6-8 g / L, the concentration of the tetrahydrothiazolyl thiophene is 2-2.5 g / L, the concentration of the fatty amine polyoxyethylene ether is 25-35 mg / L, and the concentration of the hydroxypropyl methylcellulose is 90-110 mg / L.

[0007] According to one aspect of the above technical solution, the molecular weight of the industrial collagen is 2000 Da to 5000 Da.

[0008] According to one aspect of the above technical solution, the concentration of copper sulfate is 80-100 g / L, and the concentration of sulfuric acid is 80-120 g / L.

[0009] According to one aspect of the above technical solution, the concentration of chloride ions is 20-30 mg / L.

[0010] Secondly, the present invention provides a method for preparing high tensile strength copper foil, the method comprising the following steps: placing the electrolyte described in the above technical solution into an electrolytic cell, controlling the electrolysis temperature at 40-60℃, and obtaining high tensile strength copper foil by electrolytic deposition.

[0011] Thirdly, the present invention provides a high tensile strength copper foil, which is prepared by the preparation method described in the above technical solution.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: industrial collagen and tetrahydrothiazolyl thiophene synergistically form a film, forming a uniform organic adsorption layer, inhibiting the abnormal growth of copper grains, and improving the toughness and tensile strength of copper foil; sodium dimethylformamide propane sulfonate, as a brightener, optimizes the microstructure of copper deposition, reduces grain boundary defects, and enhances mechanical properties; hydroxypropyl methylcellulose and fatty amine polyoxyethylene ether synergistically stabilize the electrolyte flow field, reduce concentration polarization, ensure uniform copper foil deposition, further optimize the mechanical properties of copper foil, and improve tensile strength; chloride ions and thiophene additives form a stable coordination system, improving the uniformity and density of copper deposition, and avoiding the risk of fracture caused by local stress concentration. Attached Figure Description

[0013] Figure 1 The images shown are scanning electron microscope (SEM) images of the first embodiment and comparative example 1 of the present invention. Part (A) is the SEM image of embodiment 1, and part (B) is the SEM image of comparative example 1. Detailed Implementation

[0014] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0015] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0017] The first embodiment of the present invention provides an electrolyte for preparing high tensile strength copper foil, comprising a main electrolyte and additives. The main electrolyte comprises copper sulfate, sulfuric acid and chloride ions. The additives comprise industrial collagen at a concentration of 5-15 g / L, sodium dimethylformamide propane sulfonate at a concentration of 4-10 g / L, tetrahydrothiazolyl thione at a concentration of 1.5-3 g / L, fatty amine polyoxyethylene ether at a concentration of 20-40 mg / L, and hydroxypropyl methylcellulose at a concentration of 80-120 mg / L.

[0018] Further, in this embodiment, the concentration of the above-mentioned industrial collagen is 8-12 g / L, the concentration of the above-mentioned sodium dimethylformamide propane sulfonate is 6-8 g / L, the concentration of the above-mentioned tetrahydrothiazolyl thiophene is 2-2.5 g / L, the concentration of the above-mentioned fatty amine polyoxyethylene ether is 25-35 mg / L, and the concentration of the above-mentioned hydroxypropyl methylcellulose is 90-110 mg / L.

[0019] Preferably, in this embodiment, the concentration of the industrial collagen is 10 g / L, the concentration of the sodium dimethylformamide propane sulfonate is 7 g / L, the concentration of tetrahydrothiazolyl thione is 2 g / L, the concentration of the fatty amine polyoxyethylene ether is 30 mg / L, and the concentration of the hydroxypropyl methylcellulose is 100 mg / L.

[0020] Furthermore, in this embodiment, the molecular weight of the industrial collagen is 2000 Da to 5000 Da. Preferably, in this embodiment, the molecular weight of the industrial collagen is 3500 Da.

[0021] In this embodiment, the concentration of copper sulfate is 80-100 g / L, the concentration of sulfuric acid is 80-120 g / L, and the concentration of chloride ions is 20-30 mg / L. Preferably, in this embodiment, the concentration of copper sulfate is 90 g / L, the concentration of sulfuric acid is 100 g / L, and the concentration of chloride ions is 25 mg / L.

[0022] The second embodiment of the present invention provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The additives include industrial collagen at a concentration of 5 g / L, sodium dimethylformamide propane sulfonate at a concentration of 3 g / L, tetrahydrothiazothione at a concentration of 1.5 g / L, fatty amine polyoxyethylene ether at a concentration of 20 mg / L, and hydroxypropyl methylcellulose at a concentration of 80 mg / L.

[0023] The third embodiment of the present invention provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte for preparing high tensile strength copper foil is basically the same as that in the first embodiment, except that: The additives include industrial-grade collagen at a concentration of 15 g / L, sodium dimethylformamide propane sulfonate at a concentration of 10 g / L, tetrahydrothiazolyl thiophene at a concentration of 3 g / L, fatty amine polyoxyethylene ether at a concentration of 40 mg / L, and hydroxypropyl methylcellulose at a concentration of 120 mg / L.

[0024] The fourth embodiment of the present invention provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The additive includes industrial collagen at a concentration of 10 g / L. The molecular weight of the industrial collagen is 3000 Da.

[0025] The fifth embodiment of the present invention provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The additive includes industrial collagen at a concentration of 10 g / L. The molecular weight of the industrial collagen is 5000 Da.

[0026] Comparative Example 1 Comparative Example 1 provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The additive contains 0% tetrahydrothiazothione.

[0027] Comparative Example 2 Comparative Example 2 provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The additives include gelatin at a concentration of 10 g / L, sodium dimethylformamide propane sulfonate at a concentration of 7 g / L, tetrahydrothiazothione at a concentration of 2 g / L, fatty amine polyoxyethylene ether at a concentration of 30 mg / L, and hydroxypropyl methylcellulose at a concentration of 100 mg / L.

[0028] Comparative Example 3 Comparative Example 3 provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The concentration of hydroxypropyl methylcellulose in the additive is 40 mg / L.

[0029] Comparative Example 4 Comparative Example 4 provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The additives include a content of 0 for medium-fatty amine polyoxyethylene ether.

[0030] Comparative Example 5 Comparative Example 5 provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The concentration of sodium dimethylformamide propane sulfonate in the additive is 2 g / L.

[0031] Comparative Example 6 Comparative Example Six provides an electrolyte for preparing high tensile strength copper foil. The formulation of this electrolyte is basically the same as that in the first embodiment, except that: The concentration of sodium dimethylformamide propane sulfonate in the additive is 15 g / L.

[0032] The electrolytes used in Examples 1 to 5 and Comparative Examples 1 to 6 for preparing high tensile strength copper foil were subjected to copper treatment. The prepared copper foils were then subjected to room temperature tensile strength testing, room temperature elongation testing, and rough surface Ra testing using a surface Ra testing machine. Testing standards: Roughness test (Rz, average roughness of ten points) was conducted according to standard GB / T29847—2013, using a German Maer M300 roughness tester to test the roughness of the matte and glossy surfaces.

[0033] The tensile strength and elongation were tested according to standard GB / T29847—2013, using a Shimadzu AGS-X-10KN room temperature tensile tester at room temperature (25℃) to test the tensile strength and elongation of the copper foil.

[0034] The experimental results are shown in the table below:

[0035] Experimental data show that the copper foil prepared in Example 1 exhibits excellent mechanical properties, with a tensile strength of 468.5 MPa. In contrast, Comparative Example 1, due to the absence of tetrahydrothiazolium thiophene, shows a significant decrease in tensile strength and a decrease in surface roughness Rz value. This phenomenon reveals the key mechanism of tetrahydrothiazolium thiophene in copper foil preparation: it can effectively reduce the diffusion coefficient of copper ions, increase the nucleation density, and promote the transformation of copper foil electrodeposition from instantaneous nucleation to continuous nucleation. Furthermore, the composite passivation film formed by tetrahydrothiazolium thiophene and collagen can significantly inhibit grain coarsening, thereby improving the tensile strength of the material. Scanning electron micrographs of Example 1 and Comparative Example 1 are shown below. Figure 1 As shown in the figure, part (A) is a scanning electron microscope image of Example 1, and part (B) is a scanning electron microscope image of Comparative Example 1.

[0036] Comparative Example 2, which used gelatin to replace industrial collagen, further validated the importance of additive selection. Test data showed that the tensile strength of the gelatin system decreased significantly, while the surface roughness increased. This is mainly attributed to the fact that the intact carboxyl and amino functional groups in the collagen molecule can form strong bonds with the copper matrix, constructing a continuous protective layer and ensuring the smoothness of the deposited surface.

[0037] Regarding surface control, in Comparative Example 3, insufficient hydroxypropyl methylcellulose concentration led to a decrease in the electrolyte's surface tension control capability and an increase in hydrogen bubble adhesion rate. This not only affected the compressive strength but also increased the surface roughness. The results of Comparative Example 4 indicate that the absence of aliphatic amine polyoxyethylene ether resulted in a lack of synergistic adsorption, increased surface tension, and a higher hydrogen bubble adhesion rate, leading to an increase in surface roughness (Rz) and a decrease in tensile strength.

[0038] Regarding the effect of sodium dimethylformamidopropanesulfonate concentration, the experimental data show a clear regularity. In Comparative Example 5, when the sodium dimethylformamidopropanesulfonate concentration was too low, the density of the copper foil decreased, and the tensile strength was significantly reduced. In Comparative Example 6, when the concentration was too high, although the grain size was further refined, the excessively high grain boundary ratio led to the obstruction of dislocation movement and the intensification of grain boundary slip, ultimately resulting in a decrease in tensile strength.

[0039] The copper foil prepared by the electrolyte used in this embodiment for preparing high tensile strength copper foil achieves comprehensive performance with a tensile strength ≥450 MPa, elongation ≥5%, and surface roughness Rz ≤2.0 μm, which is significantly better than the tetrahydrothiazolium thione-free system (Comparative Example 1), meeting the demand for high-performance copper foil in the lithium battery field.

[0040] In summary, the technical solutions described above in this invention utilize industrial collagen and tetrahydrothiazolium thione to synergistically form a uniform organic adsorption layer, inhibiting abnormal growth of copper grains and improving the toughness and tensile strength of the copper foil. Sodium dimethylformamide propane sulfonate acts as a brightener, optimizing the microstructure of copper deposition, reducing grain boundary defects, and enhancing mechanical properties. Hydroxypropyl methylcellulose and fatty amine polyoxyethylene ether synergistically stabilize the electrolyte flow field, reducing concentration polarization and ensuring uniform copper foil deposition, further optimizing the mechanical properties of the copper foil and improving tensile strength. Chloride ions and thione additives form a stable coordination system, improving the uniformity and density of copper deposition and avoiding the risk of fracture caused by localized stress concentration.

[0041] The eighth embodiment of the present invention provides a method for preparing high tensile strength copper foil, the method comprising the following steps: placing the electrolyte described in the above embodiment into an electrolytic cell, and obtaining copper foil by electrolysis.

[0042] The ninth embodiment of the present invention provides a high tensile strength copper foil, which is prepared by the preparation method described in the above embodiments.

[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An electrolyte for preparing high tensile strength copper foil, characterized in that, The product includes a main electrolyte and additives. The main electrolyte comprises copper sulfate, sulfuric acid, and chloride ions. The additives include industrial collagen at a concentration of 5-15 g / L, sodium dimethylformamide propane sulfonate at a concentration of 4-10 g / L, tetrahydrothiazolyl thione at a concentration of 1.5-3 g / L, fatty amine polyoxyethylene ether at a concentration of 20-40 mg / L, and hydroxypropyl methylcellulose at a concentration of 80-120 mg / L.

2. The electrolyte for preparing high tensile strength copper foil according to claim 1, characterized in that, The concentration of the industrial collagen is 8-12 g / L, the concentration of the sodium dimethylformamide propane sulfonate is 6-8 g / L, the concentration of the tetrahydrothiazolyl thione is 2-2.5 g / L, the concentration of the fatty amine polyoxyethylene ether is 25-35 mg / L, and the concentration of the hydroxypropyl methylcellulose is 90-110 mg / L.

3. The electrolyte for preparing high tensile strength copper foil according to claim 1, characterized in that, The molecular weight of the industrial collagen is 2000 Da to 5000 Da.

4. The electrolyte for preparing high tensile strength copper foil according to claim 1, characterized in that, The concentration of copper sulfate is 80-100 g / L, and the concentration of sulfuric acid is 80-120 g / L.

5. The electrolyte for preparing high tensile strength copper foil according to claim 1, characterized in that, The concentration of chloride ions is 20-30 mg / L.

6. A method for preparing high tensile strength copper foil, characterized in that, The method includes the following steps: placing the electrolyte according to any one of claims 1-7 into an electrolytic cell, and obtaining copper foil by electrolysis.

7. A high tensile strength copper foil, characterized in that, The copper foil is prepared by the preparation method described in claim 7.

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