Electrolytic copper foil, method for manufacturing the same, and current collector

Abstract

The present invention provides electrolytic copper foil that can maintain good high strength and elongation even after high-temperature treatment, a method for manufacturing the same, and a current collector. [Solution] The method for manufacturing electrolytic copper foil includes: providing an electrolytic apparatus including a cathode and an anode; immersing the cathode in an electrolyte; adding an additive to the electrolyte; and performing electroplating to form electrolytic copper foil on the surface of the cathode. The additive includes hydroxyethylcellulose, sodium 3-mercapto-1-propanesulfonate, ethylenethiourea, biogum, polyethyleneimine, or a combination thereof.

Description

[Technical Field]

[0001] This invention relates to electrolytic copper foil, and more particularly to electrolytic copper foil, a method for manufacturing the same, and a current collector. [Background technology]

[0002] Among energy storage components, lithium-ion secondary batteries have attracted considerable attention due to their characteristics such as the ability to repeatedly charge and discharge and their high energy density. As the demand for lighter lithium-ion batteries increases, the thickness of their internal components also needs to be reduced accordingly. However, existing internal components (such as copper foil) lose mechanical strength after high-temperature processing, making them prone to cracking and affecting the stability, safety, and performance of lithium-ion batteries. [Overview of the project] [Problems that the invention aims to solve]

[0003] This invention provides electrolytic copper foil that can maintain good high strength and elongation even after high-temperature treatment, a method for manufacturing the same, and a current collector. [Means for solving the problem]

[0004] The present invention provides a method for manufacturing electrolytic copper foil, comprising: providing an electrolytic apparatus including a cathode and an anode; immersing the cathode in an electrolyte; adding an additive to the electrolyte; and performing electroplating to form electrolytic copper foil on the surface of the cathode. The additive includes hydroxyethylcellulose, sodium 3-mercapto-1-propanesulfonate, ethylenethiourea, biogum, polyethyleneimine, or a combination thereof. The present invention also provides electrolytic copper foil and a current collector.

[0005] In one embodiment of the present invention, the concentration of the additive in the electrolyte is from 1 ppm to 25 ppm.

[0006] In one embodiment of the present invention, in the electrolyte, the concentration of hydroxyethylcellulose is 1 ppm to 10 ppm, the concentration of sodium 3-mercapto-1-propanesulfonate is 1 ppm to 10 ppm, the concentration of ethylenethiourea is 1 ppm to 10 ppm, the concentration of biogum is 1 ppm to 10 ppm, and the concentration of polyethyleneimine is 1 ppm to 10 ppm.

[0007] In one embodiment of the present invention, the electrolyte is a copper sulfate plating solution. The copper ion concentration in the copper sulfate plating solution is 60 g / L to 80 g / L, and the sulfuric acid concentration is 60 g / L to 110 g / L.

[0008] In one embodiment of the present invention, the copper sulfate plating solution further contains chloride ions at a concentration of 5 ppm to 30 ppm.

[0009] In one embodiment of the present invention, the cathode is a titanium wheel. The anode is iridium titanium oxide (IrO2 / Ti). The rotational speed of the titanium wheel is 500 rpm to 1000 rpm.

[0010] In one embodiment of the present invention, the electroplating is performed under conditions where the plating solution temperature is 50°C to 70°C and the current density is 40ASD to 60ASD.

[0011] The electrolytic copper foil of the present invention is manufactured by the electrolytic copper foil manufacturing method described above.

[0012] In one embodiment of the present invention, the thickness of the electrolytic copper foil is 3 μm to 8 μm.

[0013] In one embodiment of the present invention, the roughness of the electrolytic copper foil is 1.4 μm to 4.3 μm.

[0014] In one embodiment of the present invention, after heat treatment at 180°C to 200°C for 1 to 2 hours, the tensile strength of the electrolytic copper foil is 34 kg / mm². 2 From 58 kg / mm 2The growth rate is between 3.3% and 4.2%.

[0015] The current collector of the present invention includes the above-mentioned electrolytic copper foil. [Effects of the Invention]

[0016] Based on the above, the method for producing electrolytic copper foil of the present invention comprises adding an additive to an electrolyte into which the cathode is immersed, the additive comprising hydroxyethylcellulose, sodium 3-mercapto-1-propanesulfonate, ethylenethiourea, biogum, polyethyleneimine, or a combination thereof. This makes it possible to obtain electrolytic copper foil that can maintain good high strength and elongation even after high-temperature treatment and can be applied to current collectors.

[0017] To make the above-mentioned features and advantages of the present invention clearer and easier to understand, they will be explained in detail below with examples. [Modes for carrying out the invention]

[0018] The following are examples illustrating the content of the present invention in more detail. The details of the embodiments provided are for illustrative purposes only and do not limit the scope of the present invention. Anyone skilled in the art can modify or change these details of embodiments in accordance with the actual embodiments.

[0019] A range may be expressed in the specification as "about" one specific value to "about" another specific value, or it may be expressed directly as one specific value and / or another specific value. When a range is expressed, another embodiment includes that one specific value and / or another specific value. Similarly, when the antecedent "about" is used to express that a value is an approximation, it is understood that the specific value forms another embodiment. Furthermore, it is understood that each endpoint of a range is either explicitly related to or independent of another endpoint.

[0020] In the specification, non-limiting terms (such as possible, can, or other similar terms) are not essential or are optional implementations, incorporations, additions, or existences.

[0021] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) shall have the same meaning as commonly understood by those skilled in the technical field to which the present invention pertains. Also, terms (such as those defined in commonly used dictionaries) shall be interpreted as having a meaning consistent with their meaning in the relevant technical context, and shall not be construed in an idealized or overly formal sense unless explicitly defined as such in this specification.

[0022] The present invention provides a method for manufacturing an electrolytic copper foil, including providing an electrolytic device including a cathode and an anode, immersing the cathode in an electrolytic solution, adding an additive to the electrolytic solution, and performing electroplating to form an electrolytic copper foil on the surface of the cathode.

[0023] The cathode is not particularly limited, and an appropriate cathode can be selected as needed. In this embodiment, the cathode may be a titanium wheel or other appropriate cathode. At least a part of the cathode may be immersed in the electrolytic solution. For example, when the cathode is a titanium wheel, the titanium wheel may be rotated while at least a part of it is immersed in the electrolytic solution. The rotation speed of the titanium wheel may be from about 500 rpm to about 1000 rpm (for example, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, or any value within the above 500 rpm to 1000 rpm), and preferably from about 600 rpm to about 800 rpm.

[0024] The anode is not particularly limited, and an appropriate anode can be selected as needed. In this embodiment, the anode may be iridium titanium oxide (IrO2 / Ti) or other appropriate anode.

[0025] The electrolyte is not particularly limited, and a suitable electrolyte can be selected as needed. In this embodiment, the electrolyte may be a copper sulfate plating solution or another suitable electrolyte. The copper ion concentration in the copper sulfate plating solution may be about 60 g / L to about 80 g / L (for example, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, or any value within the range of 60 g / L to 80 g / L), and is preferably about 60 g / L to about 75 g / L. The concentration of sulfuric acid may be about 60 g / L to about 110 g / L (for example, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, or any value within the above range of 60 g / L to 110 g / L), with about 80 g / L to about 100 g / L being preferred. The copper sulfate plating solution may further contain chloride ions. The chloride ion concentration may be about 5 ppm to about 30 ppm (for example, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, or any value within the above range of 5 ppm to 30 ppm), with about 10 ppm to about 30 ppm being preferred. If the copper sulfate plating solution further contains chloride ions, the electrolytic copper foil produced by the electrolytic copper foil manufacturing method can have good roughness.

[0026] The additives include hydroxyethyl cellulose (HEC), sodium 3-mercapto-1-propanesulfonate (MPS), ethylene thiourea (ETU), bio-glue, polyethyleneimine (PEI), or a combination thereof. The additive may include one of the aforementioned specific additives, and preferably includes two or more of the aforementioned specific additives. In this embodiment, the additive preferably includes sodium 3-mercapto-1-propanesulfonate and at least one selected from the group consisting of hydroxyethyl cellulose, ethylene thiourea, bio-glue, and polyethyleneimine, and more preferably includes sodium 3-mercapto-1-propanesulfonate and ethylene thiourea and at least one selected from the group consisting of hydroxyethyl cellulose, bio-glue, and polyethyleneimine.

[0027] In the electrolyte, the concentration of the additive is about 1 ppm to about 25 ppm (for example, 1 ppm, 3 ppm, 5 ppm, 7 ppm, 9 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, or any value within the range of 1 ppm to 25 ppm), with a preference of about 12 ppm to about 23 ppm. In the electrolyte, the concentration of hydroxyethylcellulose is about 1 ppm to about 10 ppm (for example, 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, or any value within the range of 1 ppm to 10 ppm), with a preference of about 4 ppm to about 6 ppm. The concentration of sodium 3-mercapto-1-propanesulfonate is about 1 ppm to about 10 ppm (for example, 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, or any value within the range of 1 ppm to 10 ppm), with a preference of about 2 ppm to about 6 ppm. The concentration of ethylenethiourea is about 1 ppm to about 10 ppm (for example, 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, or any value within the range of 1 ppm to 10 ppm), with a preference of about 3 ppm to about 5 ppm. The concentration of biogum is about 1 ppm to about 10 ppm (for example, 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, or any value within the range of 1 ppm to 10 ppm), with a preference of about 4 ppm to about 8 ppm. The polyethyleneimine concentration is approximately 1 ppm to 10 ppm (for example, 1 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, or any value within the range of 1 ppm to 10 ppm), with approximately 3 ppm to 6 ppm being preferred.

[0028] When additives are added to the electrolyte, electrolytic copper foil produced by the electrolytic copper foil manufacturing method can maintain good high strength and elongation even after high-temperature treatment.

[0029] In this embodiment, electroplating for forming electrolytic copper foil can be carried out under the following conditions. The plating solution temperature may be about 50°C to about 70°C (for example, 50°C, 55°C, 60°C, 65°C, 70°C, or any value within the above range of 50°C to 70°C), and is preferably about 50°C to about 60°C. The current density may be about 40ASD to about 60ASD (for example, 40ASD, 45ASD, 50ASD, 55ASD, 60ASD, or any value within the above range of 40ASD to 60ASD), and is preferably about 50ASD to about 60ASD.

[0030] The electroplating time is not particularly limited, and an appropriate time can be selected as needed. For example, electroplating may be performed until an electrolytic copper foil with a thickness of approximately 3 μm to 8 μm is formed on the cathode surface.

[0031] The method for manufacturing electrolytic copper foil may further include peeling the electrolytic copper foil from the cathode surface, washing it with water, immersing it in chromic acid, washing it again with water, and then drying it. The concentration of chromic acid may be about 1.0 g / L to 2.5 g / L (for example, 1.0 g / L, 1.5 g / L, 2.0 g / L, 2.5 g / L, or any value within the above range of 1.0 g / L to 2.5 g / L), and is preferably about 1.5 g / L to about 2.0 g / L.

[0032] In this embodiment, the thickness of the electrolytic copper foil produced by the above-described method for manufacturing electrolytic copper foil may be about 3 μm to about 8 μm (for example, 3 μm, 4 μm, 6 μm, 8 μm, or any value within the range of 3 μm to 8 μm), with a preference of about 6 μm to about 8 μm. The roughness of the electrolytic copper foil may be about 1.4 μm to about 4.3 μm (for example, 1.4 μm, 2 μm, 3 μm, 4.3 μm, or any value within the range of 1.4 μm to 4.3 μm), with a preference of about 1.4 μm to about 2.0 μm.

[0033] After heat treatment at a temperature of approximately 180°C to 200°C for approximately 1 to 2 hours, the tensile strength of the electrolytic copper foil is approximately 34 kg / mm². 2 From approximately 58 kg / mm 2 (For example, 34 kg / mm 2 , 40 kg / mm 2, 50 kg / mm 2 , 58 kg / mm 2 or the above 34 kg / mm 2 to 58 kg / mm 2 Any value within may be acceptable, preferably about 46 kg / mm 2 to about 58 kg / mm 2 is preferred. The elongation rate may be about 3.3% to about 4.2% (e.g., 3.3%, 3.5%, 4.0%, 4.2% or any value within the above 3.3% to 4.2%), and preferably about 3.6% to about 4.2%. Since the electrolytic copper foil can maintain good high strength and elongation rate after high-temperature treatment, it can be applied to parts and devices manufactured through high-temperature treatment such as current collectors.

[0034] An exemplary embodiment of the present invention provides a current collector including the above electrolytic copper foil. In this embodiment, the current collector may be the negative current collector of a lithium battery. Since the thickness of the electrolytic copper foil may be about 3 μm to about 8 μm, when applied to the negative current collector of a lithium battery, the volume of the lithium battery can be reduced and / or the weight of the lithium battery can be reduced, thereby meeting the requirement of weight reduction of the lithium battery.

[0035] Hereinafter, the present invention will be described in more detail with reference to examples. The following examples are provided to illustrate the present invention, and the scope of the present invention includes the scope described in the claims and its substitutions and modifications, and is not limited to the scope of the examples.

[0036] Examples of the manufacturing method of electrolytic copper foil and the electrolytic copper foil produced thereby

[0037] Hereinafter, Examples 1 to 9 and Comparative Example 1 of the manufacturing method of electrolytic copper foil will be described.

[0038] Example 1

[0039] Using a titanium wheel as the cathode and iridium titanium oxide (IrO2 / Ti) as the anode, a copper sulfate plating solution (with a copper sulfate concentration (copper ion concentration) of approximately 60 mg / L, a sulfuric acid concentration of approximately 80 mg / L, and a chloride ion concentration of approximately 30 ppm) was used. Under conditions of a plating solution temperature of approximately 50°C, a current density of approximately 60 ASD, and a titanium wheel rotation speed of approximately 800 rpm, 5 ppm of hydroxyethyl cellulose (HEC) was added to the electrolyte, and electroplating was performed until an electrolytic copper foil approximately 6 μm thick was formed. The electrolytic copper foil was peeled off the surface of the titanium wheel, washed with water, immersed in chromic acid, washed again with water, and then dried.

[0040] Examples 2 to 9 and Comparative Example 1

[0041] The electrolytic copper foils of Examples 2 to 9 and Comparative Example 1 were manufactured using the same process as in Example 1. The only difference was that the types of components and amounts of additives used in the electrolyte and additives were changed (as shown in Table 1). The obtained electrolytic copper foils were evaluated using the evaluation methods described below, and the results are shown in Table 1.

[0042] [Table 1] *The heat treatment is performed at approximately 190°C for approximately 1 hour.

[0043] <Evaluation Method>

[0044] Roughness: The roughness of the electrolytic copper foil is tested using a laser scanning confocal microscope according to the measurement of the laser reflected light intensity. A lower roughness indicates better surface smoothness of the electrolytic copper foil.

[0045] Tensile Strength: Tensile strength tests of electrolytic copper foil are conducted using a tensile testing machine according to the engineering stress-engineered strain curve. A higher tensile strength indicates that the electrolytic copper foil has a better ability to withstand stress during processing, i.e., good mechanical strength, and is less prone to cracking.

[0046] Elongation: The elongation of electrolytic copper foil is tested using a tensile testing machine according to the engineering stress-engineered strain curve. A higher elongation indicates that the electrolytic copper foil has a superior ability to withstand volume changes during processing, meaning it has good mechanical strength and is less prone to cracking.

[0047] <Evaluation Results>

[0048] As can be seen from Table 1, when the method for manufacturing electrolytic copper foil includes adding an additive to the electrolyte, and the additive includes hydroxyethylcellulose, sodium 3-mercapto-1-propanesulfonate, ethylenethiourea, biogum, polyethyleneimine, or a combination thereof (Examples 1-9), the electrolytic copper foil produced by this method has low roughness, high tensile strength, and high elongation, meaning it has good surface smoothness and mechanical strength. In contrast, the electrolytic copper foil formed by Comparative Example 1, which does not include adding a specific additive to the electrolyte, has high roughness, low tensile strength, and low elongation, meaning it is inferior in surface smoothness and mechanical strength.

[0049] Furthermore, electrolytic copper foil produced by subjecting electrolytic copper foil to heat treatment at approximately 190°C for approximately 1 hour, and then adding a specific additive to the electrolyte in the electrolytic copper foil manufacturing method (Examples 1-9), exhibits high tensile strength and high elongation, meaning it has good thermal stability and well-maintained mechanical strength. In contrast, electrolytic copper foil produced without adding a specific additive to the electrolyte in the electrolytic copper foil manufacturing method (Comparative Example 1) exhibits low tensile strength and low elongation after heat treatment, meaning it has inferior mechanical strength.

[0050] Furthermore, compared to electrolytic copper foil produced by a method of manufacturing electrolytic copper foil with only one type of additive (Examples 1-5), the electrolytic copper foil produced by a method of manufacturing electrolytic copper foil with two or more types of additives (Examples 6-9) has a lower roughness, meaning it has better surface smoothness, and exhibits good mechanical strength both before and after heat treatment.

[0051] In summary, the present invention provides a method for producing electrolytic copper foil, which includes adding an additive to an electrolyte solution. When the additive includes hydroxyethylcellulose, sodium 3-mercapto-1-propanesulfonate, ethylenethiourea, biogum, polyethyleneimine, or a combination thereof, the resulting electrolytic copper foil can have good surface smoothness and mechanical strength, as well as good thermal stability and maintain good mechanical strength even after heat treatment. Therefore, it can be applied to current collectors such as lithium battery negative electrode current collectors and has excellent applicability.

[0052] Although the present invention has been disclosed through embodiments described above, these are not intended to limit the invention, and any person with ordinary skill in the relevant art may make several modifications and alterations without departing from the spirit and scope of the invention. The scope of protection of the present invention shall be determined by the scope of the appended patent application. [Industrial applicability]

[0053] The method for manufacturing electrolytic copper foil according to the present invention, and the electrolytic copper foil and current collector manufactured thereby, can be applied to energy storage components.

Claims

1. To provide an electrolytic apparatus including a cathode and an anode, The cathode is immersed in the electrolyte, Adding the additive to the electrolyte, Electroplating is performed to form an electrolytic copper foil on the surface of the cathode, Includes, The aforementioned additive includes hydroxyethylcellulose, sodium 3-mercapto-1-propanesulfonate, ethylenethiourea, biogum, polyethyleneimine, or a combination thereof. A method for manufacturing electrolytic copper foil.

2. In the electrolyte, the concentration of the additive is between 1 ppm and 25 ppm. The method for producing electrolytic copper foil according to claim 1.

3. In the electrolyte, the concentration of hydroxyethylcellulose is 1 ppm to 10 ppm, the concentration of sodium 3-mercapto-1-propanesulfonate is 1 ppm to 10 ppm, the concentration of ethylenethiourea is 1 ppm to 10 ppm, the concentration of biogum is 1 ppm to 10 ppm, and the concentration of polyethyleneimine is 1 ppm to 10 ppm. The method for producing electrolytic copper foil according to claim 1.

4. The electrolyte is a copper sulfate plating solution, the copper ion concentration in the copper sulfate plating solution is 60 g / L to 80 g / L, and the sulfuric acid concentration is 60 g / L to 110 g / L. The method for producing electrolytic copper foil according to claim 1.

5. The copper sulfate plating solution further contains chloride ions at a concentration of 5 ppm to 30 ppm. The method for manufacturing electrolytic copper foil according to claim 4.

6. The cathode is a titanium wheel, and the anode is iridium titanium oxide (IrO ２ The coefficient of rotation of the titanium wheel is 500 rpm to 1000 rpm. The method for producing electrolytic copper foil according to claim 1.

7. The aforementioned electroplating is performed under the conditions that the plating solution temperature is 50°C to 70°C and the current density is 40 ASD to 60 ASD. The method for producing electrolytic copper foil according to claim 1.

8. Electrolytic copper foil produced by the method for producing electrolytic copper foil according to any one of claims 1 to 7.

9. The thickness of the electrolytic copper foil is 3 μm to 8 μm. The electrolytic copper foil according to claim 8.

10. The roughness of the electrolytic copper foil is 1.4 μm to 4.3 μm. The electrolytic copper foil according to claim 8.

11. After heat treatment at 180°C to 200°C for 1 to 2 hours, the tensile strength of the electrolytic copper foil is 34 kg / mm². ２ From 58 kg / mm ２ The growth rate is between 3.3% and 4.2%. The electrolytic copper foil according to claim 8.

12. A current collector comprising the electrolytic copper foil described in claim 8.

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