Additive for high-elongation ultrathin electrolytic copper foil and preparation process of electrolytic copper foil

Abstract

The invention provides an additive for a high-elongation ultrathin electrolytic copper foil and a preparation process of the electrolytic copper foil, and belongs to the technical field of electrolytic copper foils. The additive is formed by mixing an additive component A, an additive component B, an additive component C and an additive component D, wherein the additive component A is a 3-(benzothiazole-2-sulfydryl) sodium propanesulfonate solution, the additive component B is a fish gelatin solution, the additive component C is a polyethylene glycol solution, and the additive component D is a polyvinyl acetate solution. The preparation process for preparing the high-elongation ultrathin electrolytic copper foil comprises the following steps: preparing a copper sulfate electrolyte: dissolving a copper wire and sulfuric acid in high-purity water under the participation of pure air to prepare the copper sulfate electrolyte; and pouring the copper sulfate electrolyte into a clean liquid tank, then adding the additive into the copper sulfate electrolyte, and then introducing the copper sulfate electrolyte into equipment for electrolyzing crude foil to prepare the copper foil. According to the invention, fish gelatin is adopted to replace traditional collagen, and polyvinyl acetate and fish gelatin are added to act together, so that the tensile strength of the copper foil is improved, and the elongation is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electrolytic copper foil, and in particular relates to an additive for a high-elongation ultra-thin electrolytic copper foil and a preparation process of the electrolytic copper foil. Background Art

[0002] Electrolytic copper foil not only plays an important role in the fields of copper clad laminates and printed circuit boards, but also has been widely used in the field of lithium batteries with the development of the new energy electric vehicle industry. The physical properties of copper foil also affect the performance of lithium batteries, so higher-end copper foil products have gradually become the mainstream of the market. Compared with copper foil of ordinary thickness, thinner copper foil can significantly improve the energy density of the battery. Improving the physical properties of copper foil while reducing the thickness of copper foil has become the focus of research. According to existing theoretical and experimental data, the thinning of copper foil will reduce the elongation, and the elongation is an important physical property indicator for evaluating the quality of copper foil. Because lithium batteries will expand during the charging and discharging process, low elongation will cause cracks due to expansion, thereby causing battery failure. Therefore, ultra-thin copper foil widely used in the lithium battery industry needs to effectively improve the elongation while maintaining standard tensile strength, brightness, etc. Traditional cowhide collagen has limitations in improving elongation, so the present invention proposes to use fish glue instead of traditional collagen, combined with polyvinyl acetate, and combined with other grain refiners, which can effectively improve the elongation while maintaining high tensile strength. Summary of the invention

[0003] The technical problem solved by the present invention is to provide an additive for ultra-thin electrolytic copper foil with high elongation and a preparation process of electrolytic copper foil. The present invention aims to use fish glue instead of traditional collagen in the electrolytic copper foil additive, and add polyvinyl acetate to work together with fish glue to achieve the effect of improving the tensile strength of the copper foil while effectively improving the elongation.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] An additive for high-elongation ultra-thin electrolytic copper foil, the additive is a mixture of four additive components A, B, C, and D, wherein additive A is a sodium 3-(benzothiazole-2-mercapto) propane sulfonate solution, additive B is a fish glue solution, additive C is a polyethylene glycol solution, and additive D is a polyvinyl acetate solution;

[0006] Among them, the mass concentration of sodium 3-(benzothiazole-2-mercapto)propane sulfonate is 5-10 mg / L; the mass concentration of fish glue is 6-10 mg / L; the mass concentration of polyethylene glycol is 3-5 mg / L; and the mass concentration of polyvinyl acetate is 50-100 mg / L.

[0007] The process for preparing a highly elongated ultra-thin electrolytic copper foil using the additive according to claim 1 comprises the following steps:

[0008] Step 1): preparing a copper sulfate electrolyte: dissolving copper wire and sulfuric acid in high-purity water in the presence of pure air to prepare a copper sulfate electrolyte;

[0009] Step 2): Pour the copper sulfate electrolyte obtained in step 1) into a clean liquid tank, then add the additive in claim 1 to the copper sulfate electrolyte, and then pass the copper sulfate electrolyte into the electrolytic foil production equipment, connect direct current, and produce copper foil.

[0010] In the above step 1), the copper ion mass concentration in the copper sulfate electrolyte is 80-100 g / L, the H2SO4 mass concentration is 120-140 g / L, and the chloride ion mass concentration is 20-30 ppm.

[0011] In the above step 1), the temperature of the copper sulfate electrolyte is 48-54°C, and the cathode surface current density is 3000-3500A / m 2 .

[0012] The advantages of the present invention compared with the prior art are:

[0013] 1. This solution is aimed at the fact that most of the collagen used in the prior art is collected from cowhide, which has no particularly significant effect on the elongation. The present invention not only uses fish glue to replace traditional collagen, but also adds polyvinyl acetate to work together with fish glue, which effectively improves the elongation while improving the tensile strength of the copper foil;

[0014] 2. The high-elongation ultra-thin electrolytic copper foil of this scheme is made of additives and electrolyte, and the roughness of the electrolytic copper foil is ≤1.82 microns, the tensile strength at room temperature before heat treatment is 405-425MPa, and the elongation at room temperature before heat treatment is ≥11%; the electrolytic copper foil ensures the high tensile strength of the copper foil while effectively improving the elongation of the ultra-thin copper foil at room temperature. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Embodiment: An additive for high-elongation ultra-thin electrolytic copper foil, the additive is a mixture of four additive components A, B, C, and D, wherein additive A is a sodium 3-(benzothiazole-2-mercapto) propane sulfonate solution, additive B is a fish glue solution, additive C is a polyethylene glycol solution, and additive D is a polyvinyl acetate solution;

[0017] Among them, the mass concentration of sodium 3-(benzothiazole-2-mercapto)propane sulfonate is 5-10 mg / L; the mass concentration of fish glue is 6-10 mg / L; the mass concentration of polyethylene glycol is 3-5 mg / L; and the mass concentration of polyvinyl acetate is 50-100 mg / L.

[0018] In the above-mentioned additive formula of this embodiment:

[0019] The standard addition concentration of sodium 3-(benzothiazole-2-mercapto)propane sulfonate as a grain refiner is 5 to 10 mg / L. When the concentration is less than 5 mg / L, the brightness of the copper foil will decrease and the crystals will become rough. When the concentration is greater than 10 mg / L, the internal stress of the copper foil will increase and pinholes will appear on the foil surface.

[0020] The concentration of fish glue added is 6-10 mg / L. When the concentration is less than 6 mg / L, the brightness of the copper foil will decrease. When it exceeds 10 mg / L, the smoothness of the copper foil will decrease and the crystallization will become rough.

[0021] As a wetting agent, polyethylene glycol can improve the wettability of copper foil and alleviate warping. The input concentration is 3-5 mg / L. When the polyethylene glycol concentration is lower than 3 mg / L, the wettability will decrease, resulting in a decrease in brightness. When the content is higher than 5 mg / L, the crystallization will become rough, which will in turn lead to a decrease in the tensile strength and elongation of the copper foil.

[0022] Polyvinyl acetate can effectively improve the deposition efficiency of copper ions and enhance the ion binding force. When combined with fish glue, it can significantly improve the elongation of copper foil. When the concentration is lower than 50 mg / L, it cannot effectively improve the elongation. When the concentration is higher than 100 mg / L, it makes the grains rough, and the tensile strength and elongation decrease.

[0023] Since the collagen used in the prior art is mostly collected from cowhide, it has no particularly significant effect on the elongation. Therefore, the present invention not only uses fish glue to replace traditional collagen, but also adds polyvinyl acetate to work together with fish glue, which effectively improves the elongation while improving the tensile strength of the copper foil.

[0024] The process for preparing a highly elongated ultra-thin electrolytic copper foil using the above-mentioned additives comprises the following steps:

[0025] Step 1): preparing a copper sulfate electrolyte: dissolving copper wire and sulfuric acid in high-purity water in the presence of pure air to prepare a copper sulfate electrolyte;

[0026] Step 2): Pour the copper sulfate electrolyte obtained in step 1) into a clean liquid tank, then add the above additives into the copper sulfate electrolyte, and then pass the copper sulfate electrolyte into the electrolytic foil production equipment, connect direct current, and produce copper foil.

[0027] In the above step 1), the copper ion mass concentration in the copper sulfate electrolyte is 80-100 g / L, the H2SO4 mass concentration is 120-140 g / L, and the chloride ion mass concentration is 20-30 ppm.

[0028] In the above step 1), the temperature of the copper sulfate electrolyte is 48-54°C, and the cathode surface current density is 3000-3500A / m 2 .

[0029] Generally speaking, when pinholes appear on the surface of copper foil, it will affect the appearance and secondary processing of downstream manufacturers. The preparation process of this embodiment is suitable for producing copper foil of 6 to 10 microns. When the thickness is less than 6 microns, the copper foil is prone to breakage, wrinkles and other undesirable phenomena during the production process, and the machine needs to be readjusted to continue production, which reduces production efficiency. However, when the thickness is greater than 10 microns, it is not conducive to achieving high energy density.

[0030] The electrolytic copper foil prepared by the present invention using the above additives and electrolyte has a roughness of ≤1.82 microns, a room temperature tensile strength of 405-425 MPa before heat treatment, and a room temperature elongation of ≥11% before heat treatment. In summary, the present invention effectively improves the room temperature elongation of the ultra-thin copper foil while ensuring the high tensile strength of the copper foil.

[0031] The technical solution of the present invention is described below by comparing the specific embodiments of the present invention with the comparative examples.

[0032] This embodiment and the comparative example both use a copper sulfate electrolyte with a copper ion content of 90 g / L, a H2SO4 concentration of 140 g / L, and a chloride ion content of 25 ppm, wherein the electrolyte temperature is 51 ± 3 ° C, the cathode current density is 3500 A / m 2 The prepared copper sulfate electrolyte is poured into the clean liquid tank, and the additives added into the clean liquid tank are as shown in the following table:

[0033] Group A dose (mg / L) Agent B (mg / L) Agent C (mg / L) Agent D (mg / L) Example 1 5.1 6.3 3 51 Example 2 6.6 6.9 3.2 64.8 Example 3 7.2 7.8 3.7 77 Example 4 8.9 8.5 4.1 82 Example 5 9.4 9.4 4.4 89.5 Example 6 10 10.2 4.9 97.8 Comparative Example 1 6.8 0 3.3 66 Comparative Example 2 7.9 0 4 0 Comparative Example 3 2.5 7.5 1.5 0 Comparative Example 4 3.7 3.3 2.1 21 Comparative Example 5 13.4 12.7 8.6 127 Comparative Example 6 15.8 14.2 9.4 120

[0034] The copper foil with a thickness of 6 microns was prepared by the above scheme, and the tensile strength, elongation, brightness and roughness were tested. The specific test results are as follows:

[0035]

[0036] In summary, the room temperature elongation of the electrolytic copper foil of Examples 1-6 before heat treatment is ≥11%, the tensile strength before heat treatment is 405-425MPa, and the foil surface roughness is low and the brightness is high, without poor appearance. When no fish glue or polyvinyl acetate is added, the elongation of Comparative Examples 1-3 decreases significantly. When the additive is lower than the reference value or exceeds the standard, the roughness of the foil surface of Comparative Examples 4-6 increases, and the elongation, tensile strength and brightness all decrease significantly, and pinholes will appear on the foil surface when excessive addition is made, affecting the yield. Therefore, the electrolytic copper foil manufactured by the process of Examples 1-6 has the characteristics of high elongation, high tensile strength, low roughness and high brightness, and can be stably mass-produced.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0038] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An additive for high-elongation ultra-thin electrolytic copper foil, characterized in that: The additive is a mixture of four additive components A, B, C and D, wherein the additive A is a sodium 3-(benzothiazole-2-mercapto) propane sulfonate solution, the additive B is a fish glue solution, the additive C is a polyethylene glycol solution, and the additive D is a polyvinyl acetate solution; Among them, the mass concentration of sodium 3-(benzothiazole-2-mercapto)propane sulfonate is 5-10 mg / L; the mass concentration of fish glue is 6-10 mg / L; the mass concentration of polyethylene glycol is 3-5 mg / L; and the mass concentration of polyvinyl acetate is 50-100 mg / L.

2. A process for preparing a highly elongated ultra-thin electrolytic copper foil using the additive according to claim 1, characterized in that: The following steps are involved: Step 1): preparing a copper sulfate electrolyte: dissolving copper wire and sulfuric acid in high-purity water in the presence of pure air to prepare a copper sulfate electrolyte; Step 2): Pour the copper sulfate electrolyte obtained in step 1) into a clean liquid tank, then add the additive in claim 1 to the copper sulfate electrolyte, and then pass the copper sulfate electrolyte into the electrolytic foil production equipment, connect direct current, and produce copper foil.

3. The process for preparing the high-elongation ultra-thin electrolytic copper foil according to claim 2, characterized in that: In the above step 1), the copper ion mass concentration in the copper sulfate electrolyte is 80-100 g / L, the H2SO4 mass concentration is 120-140 g / L, and the chloride ion mass concentration is 20-30 ppm.

4. The process for preparing the high-elongation ultra-thin electrolytic copper foil according to claim 2, characterized in that: In the above step 1), the temperature of the copper sulfate electrolyte is 48-54°C, and the cathode surface current density is 3000-3500A / m 2 .

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