High-strength ultra-thin copper foil with dispersion strengthened copper composite structure and preparation method of high-strength ultra-thin copper foil

Abstract

The invention belongs to the technical field of composite ultra-thin copper foil manufacturing, and particularly relates to a high-strength ultra-thin copper foil with a dispersion strengthened copper composite structure and a preparation method of the high-strength ultra-thin copper foil. On the basis of the prior art, the aluminum foil is subjected to single-side copper plating through the vacuum magnetron sputtering technology, then a copper layer is thickened through the water electroplating technology, part of aluminum atoms are dissolved in a copper matrix through high-temperature treatment, the aluminum layer is stripped through electrochemical treatment, nano cuprous oxide powder is modified through bis (trimethylsiloxy) methylsilane, and the copper-clad aluminum foil is obtained. The preparation method comprises the following steps: firstly preparing nano cuprous oxide, then compounding the nano cuprous oxide with chitosan and 1H-benzimidazole-5, 6-diol to obtain a surface treating agent, enhancing the interface bonding capacity of the surface of the copper foil and the nano cuprous oxide, and then converting aluminum solute atoms in the surface layer of the copper foil into a nano Al2O3 reinforced phase through high-temperature internal oxidation treatment, so that the dislocation motion of the copper foil can be effectively hindered, and the copper foil can be effectively prevented from being oxidized. And moreover, the influence on the conductivity of copper is small, and the prepared ultrathin copper foil has excellent mechanical property, conductivity and high-temperature creep property.

Description

Technical Field

[0001] The invention belongs to the technical field of composite ultra-thin copper foil production, and in particular relates to a high-strength ultra-thin copper foil with a dispersion-strengthened copper composite structure and a preparation method thereof. Background Art

[0002] Ultra-thin copper foil usually refers to copper foil with a thickness of less than 9μm. With the growing development of electronic information technology, high-performance lithium batteries require copper foil to develop in the direction of better performance and thinner thickness. Therefore, the demand for ultra-thin copper foil is increasing, especially ultra-thin copper foil with a thickness of 5μm or less. Due to the limitation of production equipment, the thickness of rolled copper foil is difficult to be less than 6μm. At present, the production of ultra-thin copper foil is mainly electroplated copper foil, and the higher the performance requirements of lithium battery copper foil, the more difficult the process is, so that my country's high-end lithium battery copper foil has long relied on imports. Because the thickness of ultra-thin copper foil is less than 9μm, it is very easy to curl and bend during the production and application process, and the mechanical properties of ultra-thin copper foil will also be reduced as the thickness is reduced.

[0003] The Chinese invention patent with publication number CN114045536B discloses a method for preparing a gradient ultra-thin copper foil with both high strength and high ductility, comprising the following steps: step S1, preparing a titanium foil substrate with a clean surface; step S2, mixing and dissolving copper sulfate pentahydrate, concentrated sulfuric acid, and additives in proportion to obtain a deposition electrolyte solution, wherein the amounts of copper sulfate pentahydrate and concentrated sulfuric acid are 140-240 g / L and 100-150 mM, respectively; step S3, preparing copper foil by electrochemical deposition, with a current range of 0-700 mA / cm 2 The obtained copper foil has a uniformly changing gradient structure, and can simultaneously improve the mechanical properties of the copper foil, such as tensile strength and stretchability, while ensuring that it has an ultra-thin thickness of 5-35 μm. However, the existing technology has the technical problems that ultra-thin copper foil is difficult to prepare and has insufficient strength performance. Summary of the invention

[0004] The object of the present invention is to provide a high-strength ultra-thin copper foil with a dispersion-strengthened copper composite structure and a preparation method thereof, so as to solve the technical problems in the prior art that ultra-thin copper foil is difficult to prepare and has insufficient strength performance.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure comprises the following steps: S1. After removing the oxide layer by sandpaper polishing, the aluminum foil with a thickness of 0.03-0.06 μm was added to 90-95 wt % ethanol for washing for 5-10 min, then washed with 5-10 wt % acetic acid for 5-8 min, and finally rinsed with deionized water for 2-3 times, and dried at 40-60 ° C to obtain the pretreated aluminum foil; S2, copper-plating the pretreated aluminum foil on one side by vacuum magnetron sputtering technology, controlling the thickness of the single-sided copper layer to be 30-60 nm, and then thickening the copper layer by 3-5 μm by water electroplating technology to obtain a copper-aluminum composite foil; S3, after rolling and compacting the copper-aluminum composite foil, placing it in a resistance furnace and heating it at 300-400° C. for 2-4 hours to form a copper-aluminum composite foil with a three-layer structure of aluminum / copper-aluminum solid solution / copper; S4, placing the copper-aluminum composite foil into an electrolytic cell, with the copper layer as the negative electrode and the aluminum layer as the positive electrode, and electrolyzing and dissolving the aluminum layer to obtain an extremely thin composite copper layer; S5. Coating a surface treatment agent on the surface of the ultra-thin composite copper layer, and subjecting it to a high-temperature heat treatment at 800-950° C. in an argon atmosphere to form a dispersion-strengthened copper composite foil.

[0006] Preferably, the vacuum degree of vacuum magnetron sputtering in S2 is lower than 2-3×10 -4 MPa, the sputtering power is 50~60W, the working pressure is 0.5~0.6Pa, the aluminum foil temperature is 150~200℃, the atmosphere is either argon or nitrogen, and the target material is pure copper target with a purity of more than 99.999%.

[0007] Preferably, the copper plating solution for water electroplating in S2 consists of 80-100 g / L copper sulfate, 0.05-0.1 g / L sodium chloride, 0.2-0.5 g / L polyethylene glycol and 90-100 g / L sulfuric acid.

[0008] Preferably, the working temperature of the water electroplating in S2 is 40-50°C, the circulation rate of the copper plating solution is 2-4 L / min, and the current density ranges from 300-500 A / m 2 , the plating time is 30~60s.

[0009] Preferably, the electrolyte composition in S4 consists of 60-70 g / L sulfuric acid, 30-50 g / L copper sulfate, 3-6 g / L sodium carboxymethyl cellulose, 20-25 g / L sodium potassium tartrate, 1-2 g / L disodium ethylenediaminetetraacetate and 0.2-0.5 g / L sodium polydisulfide dipropane sulfonate.

[0010] Preferably, the current density in S4 is in the range of 100-800 A / m 2 , the electrolytic cell voltage range is 0.5~5V.

[0011] Preferably, the method for preparing the surface treatment agent in S5 comprises the following steps: S11, adding 0.05-0.06 parts of copper acetate to 50 parts of deionized water, heating in an oil bath to 70-80°C, adding dropwise 20-30 parts of 70-80 g / L sodium hydroxide solution, and finally adding dropwise 5-6 parts of 300 g / L glucose solution, reacting for 2-3 hours, filtering and collecting the solid, and drying at 50-60°C to obtain nano cuprous oxide powder; S12, adding bistrimethylsiloxymethylsilane to deionized water, heating at 70-80°C for 1-2h, adding nano cuprous oxide powder under stirring, controlling the pH to 7.5-8.5, reacting at 70-80°C for 20-24h, filtering and drying to obtain modified nano cuprous oxide powder; S13, dissolving 0.5-0.6 parts of chitosan in 100 parts of deionized water, stirring at 40-50° C. for 1-2 hours, adding 0.5-0.8 parts of modified nano cuprous oxide powder and 0.3-0.5 parts of 1H-benzimidazole-5,6-diol to prepare a surface treatment agent.

[0012] Preferably, the mass ratio of bistrimethylsiloxymethylsilane to nano cuprous oxide powder in the S12 is 0.5-0.8:1.

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. Based on the prior art, the present invention uses vacuum magnetron sputtering technology to plate copper on one side of aluminum foil, then uses water electroplating technology to thicken the copper layer, and then uses electrochemical treatment to peel off the aluminum layer after high-temperature treatment after rolling, and then uses high-temperature internal oxidation treatment to obtain an ultra-thin copper foil with excellent mechanical properties, electrical conductivity and high-temperature creep properties.

[0014] 2. The present invention forms a layer of copper-aluminum alloy on the sputtering surface of the copper layer of the copper-aluminum composite foil through heat treatment. The copper foil is relatively thick and it is difficult to fully diffuse aluminum into the copper. The high-temperature internal oxidation treatment converts aluminum solute atoms into nano-Al2O3 reinforcement phases, which can effectively hinder the dislocation movement of the copper foil and has little effect on the electrical conductivity of copper. Therefore, the copper foil with a dispersion-strengthened copper composite structure has good electrical conductivity and improved tensile strength of the copper foil.

[0015] 3. The present invention modifies nano cuprous oxide powder by bistrimethylsiloxymethylsilane, and then compounding with chitosan and 1H-benzimidazole-5,6-diol to obtain a surface treatment agent, which enhances the interface bonding ability between the copper foil surface and the nano cuprous oxide, makes it easier to form a dense oxide film on the copper foil surface, thereby improving the corrosion resistance of the copper foil. DETAILED DESCRIPTION

[0016] 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 the embodiments. 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.

[0017] Embodiment 1: The method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure of this embodiment comprises the following steps: S1. After removing the oxide layer by sandpaper polishing, the aluminum foil with a thickness of 0.06 μm was added to 95 wt % ethanol for 10 min, then washed with 5 wt % acetic acid for 8 min, and finally rinsed with deionized water for 3 times, and dried at 60° C. to obtain the pretreated aluminum foil; S2. The pretreated aluminum foil is copper plated on one side by vacuum magnetron sputtering technology. The vacuum degree of vacuum magnetron sputtering is less than 3×10 -4 MPa, the sputtering power is 60W, the working pressure is 0.6Pa, the aluminum foil temperature is 200℃, the sputtering working atmosphere is argon, the target material is a pure copper target with a purity of more than 99.999%, the thickness of the single-sided copper layer is controlled to be 60nm, and a copper plating solution composed of 100g / L copper sulfate, 0.05g / L sodium chloride, 0.2g / L polyethylene glycol and 98g / L sulfuric acid is prepared. The circulation rate of the copper plating solution is set to 4L / min, and the current density is 300A / m 2 , the plating time is 40s, the copper layer is thickened by 3.5μm, and a copper-aluminum composite foil is obtained; S3, after rolling and compacting the copper-aluminum composite foil, placing it in a resistance furnace and heating it at 400° C. for 4 hours to form a copper-aluminum composite foil with a three-layer structure of aluminum / copper-aluminum solid solution / copper; S4, prepare an electrolyte consisting of 65g / L sulfuric acid, 40g / L copper sulfate, 5g / L sodium carboxymethyl cellulose, 20g / L sodium potassium tartrate, 2g / L disodium ethylenediaminetetraacetic acid and 0.2g / L sodium polydisulfide dipropane sulfonate, put the copper-aluminum composite foil into the electrolytic cell, with the copper layer as the negative electrode and the aluminum layer as the positive electrode, and the current density is 400A / m 2 , the voltage of the electrolytic cell is 3V, and the aluminum layer is electrolytically dissolved to obtain an extremely thin composite copper layer; S5. Coating a surface treatment agent on the surface of the ultra-thin composite copper layer, and subjecting the layer to a high-temperature heat treatment at 850° C. in an argon atmosphere to form a dispersion-strengthened copper composite foil.

[0018] The preparation method of the surface treatment agent of this embodiment comprises the following steps: S11, add 0.06 parts of copper acetate to 50 parts of deionized water, heat to 80°C in an oil bath, then drop 20 parts of 75g / L sodium hydroxide solution, and finally drop 5 parts of 300g / L glucose solution, react for 2.5h, filter and collect the solid, and dry at 60°C to obtain nano cuprous oxide powder; S12, adding 0.025 parts of bistrimethylsiloxymethylsilane to deionized water, heating at 80°C for 2h, adding 0.05 parts of nano cuprous oxide powder under stirring, controlling the pH to 8, reacting at 80°C for 24h, filtering and drying to obtain modified nano cuprous oxide powder; S13, dissolving 0.6 parts of chitosan in 100 parts of deionized water, stirring at 50° C. for 2 hours, adding 0.5 parts of modified nano cuprous oxide powder and 0.3 parts of 1H-benzimidazole-5,6-diol to prepare a surface treatment agent.

[0019] Embodiment 2: The method for preparing the high-strength ultra-thin copper foil with a dispersion-strengthened copper composite structure of this embodiment comprises the following steps: S1. After removing the oxide layer by sandpaper polishing, the aluminum foil with a thickness of 0.06 μm was added to 95 wt % ethanol for 10 min, then washed with 5 wt % acetic acid for 8 min, and finally rinsed with deionized water for 3 times, and dried at 60° C. to obtain the pretreated aluminum foil; S2. The pretreated aluminum foil is copper plated on one side by vacuum magnetron sputtering technology. The vacuum degree of vacuum magnetron sputtering is less than 2×10 -4 MPa, the sputtering power is 55W, the working pressure is 0.5Pa, the aluminum foil temperature is 160℃, the sputtering working atmosphere is argon, the target material is a pure copper target with a purity of more than 99.999%, the thickness of the single-sided copper layer is controlled to be 55nm, and a copper plating solution composed of 80g / L copper sulfate, 0.1g / L sodium chloride, 0.5g / L polyethylene glycol and 100g / L sulfuric acid is prepared. The circulation rate of the copper plating solution is set to 2L / min, and the current density is 500A / m 2 , the plating time is 30s, the copper layer is thickened by 4μm, and a copper-aluminum composite foil is obtained; S3, after rolling and compacting the copper-aluminum composite foil, placing it in a resistance furnace and heating it at 350° C. for 3 h to form a copper-aluminum composite foil with a three-layer structure of aluminum / copper-aluminum solid solution / copper; S4, prepare an electrolyte consisting of 70g / L sulfuric acid, 40g / L copper sulfate, 3g / L sodium carboxymethyl cellulose, 21g / L potassium sodium tartrate, 1.2g / L disodium ethylenediaminetetraacetate and 0.3g / L sodium polydisulfide dipropane sulfonate, put the copper-aluminum composite foil into the electrolytic cell, with the copper layer as the negative electrode and the aluminum layer as the positive electrode, and the current density is 100A / m 2 , the electrolytic cell voltage is 0.8V, and the aluminum layer is electrolytically dissolved to obtain an extremely thin composite copper layer; S5. Coating a surface treatment agent on the surface of the ultra-thin composite copper layer, and subjecting the layer to a high-temperature heat treatment at 800° C. in an argon atmosphere to form a dispersion-strengthened copper composite foil.

[0020] The preparation method of the surface treatment agent of this embodiment is the same as that of embodiment 1.

[0021] Embodiment 3, the preparation method of the high-strength ultra-thin copper foil with a dispersion-strengthened copper composite structure of this embodiment comprises the following steps: S1. After removing the oxide layer by sandpaper polishing, the aluminum foil with a thickness of 0.06 μm was added to 95 wt % ethanol for 10 min, then washed with 5 wt % acetic acid for 8 min, and finally rinsed with deionized water for 3 times, and dried at 60° C. to obtain the pretreated aluminum foil; S2. The pretreated aluminum foil is copper plated on one side by vacuum magnetron sputtering technology. The vacuum degree of vacuum magnetron sputtering is less than 3×10 -4 MPa, the sputtering power is 50W, the working pressure is 0.5Pa, the aluminum foil temperature is 180℃, the sputtering working atmosphere is nitrogen, the target material is a pure copper target with a purity of more than 99.999%, the thickness of the single-sided copper layer is controlled to be 60nm, and a copper plating solution composed of 85g / L copper sulfate, 0.075g / L sodium chloride, 0.5g / L polyethylene glycol and 90g / L sulfuric acid is prepared. The copper layer is thickened by 3μm through water electroplating technology to obtain a copper-aluminum composite foil; S3, after rolling and compacting the copper-aluminum composite foil, placing it in a resistance furnace and heating it at 450° C. for 2 h to form a copper-aluminum composite foil with a three-layer structure of aluminum / copper-aluminum solid solution / copper; S4, prepare an electrolyte consisting of 65g / L sulfuric acid, 50g / L copper sulfate, 6g / L sodium carboxymethyl cellulose, 25g / L potassium sodium tartrate, 1.6g / L disodium ethylenediaminetetraacetate and 0.4g / L sodium polydisulfide dipropane sulfonate, put the copper-aluminum composite foil into the electrolytic cell, with the copper layer as the negative electrode and the aluminum layer as the positive electrode, and the current density is 500A / m 2 , the voltage of the electrolytic cell is 5V, and the aluminum layer is electrolytically dissolved to obtain an extremely thin composite copper layer; S5. Coating a surface treatment agent on the surface of the ultra-thin composite copper layer, and subjecting it to a high-temperature heat treatment at 950° C. in an argon atmosphere to form a dispersion-strengthened copper composite foil.

[0022] The preparation method of the surface treatment agent of this embodiment is the same as that of embodiment 1.

[0023] Embodiment 4, the preparation method of the high-strength ultra-thin copper foil with a dispersion-strengthened copper composite structure of this embodiment comprises the following steps: S1. After removing the oxide layer by sandpaper polishing, the aluminum foil with a thickness of 0.06 μm was added to 95 wt % ethanol for 10 min, then washed with 5 wt % acetic acid for 8 min, and finally rinsed with deionized water for 3 times, and dried at 60° C. to obtain the pretreated aluminum foil; S2. The pretreated aluminum foil is copper plated on one side by vacuum magnetron sputtering technology. The vacuum degree of vacuum magnetron sputtering is less than 2.5×10 -4 MPa, the sputtering power is 60W, the working pressure is 0.6Pa, the aluminum foil temperature is 190℃, the sputtering working atmosphere is nitrogen, the target material is a pure copper target with a purity of more than 99.999%, the thickness of the single-sided copper layer is controlled to be 30nm, and a copper plating solution composed of 100g / L copper sulfate, 0.06g / L sodium chloride, 0.5g / L polyethylene glycol and 100g / L sulfuric acid is configured. The circulation rate of the copper plating solution is set to 3L / min, and the current density is 500A / m 2 , the plating time is 60s, the copper layer is thickened by 5μm, and a copper-aluminum composite foil is obtained; S3, after rolling and compacting the copper-aluminum composite foil, placing it in a resistance furnace and heating it at 400° C. for 4 hours to form a copper-aluminum composite foil with a three-layer structure of aluminum / copper-aluminum solid solution / copper; S4, prepare an electrolyte consisting of 70g / L sulfuric acid, 30g / L copper sulfate, 4g / L sodium carboxymethyl cellulose, 20g / L potassium sodium tartrate, 1g / L disodium ethylenediaminetetraacetic acid and 0.5g / L sodium polydisulfide dipropane sulfonate, put the copper-aluminum composite foil into the electrolytic cell, with the copper layer as the negative electrode and the aluminum layer as the positive electrode, and the current density is 500A / m 2 , the voltage of the electrolytic cell is 5V, and the aluminum layer is electrolytically dissolved to obtain an extremely thin composite copper layer; S5. Coating a surface treatment agent on the surface of the ultra-thin composite copper layer, and subjecting the layer to a high-temperature heat treatment at 900° C. in an argon atmosphere to form a dispersion-strengthened copper composite foil.

[0024] The difference between the surface treatment agent of this embodiment and that of Embodiment 1 is that the mass ratio of bistrimethylsiloxymethylsilane to nano cuprous oxide powder is 0.8:1.

[0025] Comparative Example 1: The difference between this comparative example and Example 1 is that in step S3, there is no rolling and direct heat treatment.

[0026] Comparative Example 2: This comparative example differs from Example 1 in that the surface treatment agent is replaced by chitosan and nano cuprous oxide powder.

[0027] Comparative Example 3: The difference between this comparative example and Example 1 is that the thickness of the water electroplating thickened copper layer is replaced with 1 μm.

[0028] Performance Testing The peel strength of the copper foils prepared in each embodiment and comparative example was measured by a peel strength tester, and the tensile strength was measured by a universal testing machine. The test results are shown in Table 1 below: Serial number Peel strength (N / mm) Tensile strength (MPa) Example 1 0.61 195 Example 2 0.55 201 Example 3 0.59 198 Example 4 0.57 205 Comparative Example 1 0.36 167 Comparative Example 2 0.54 188 Comparative Example 3 0.33 146 Table 1 The density of the copper foils prepared in each embodiment and comparative example was measured several times, and the average value was taken; the conductivity was measured by a desktop conductivity meter, and the test results are shown in Table 2 below: Table 2 Serial number <![CDATA[Density (g / cm 2 )]]> Conductivity (S / m) Example 1 7.26 <![CDATA[5.76×10 7 ]]> Example 2 7.32 <![CDATA[5.77×10 7 ]]> Example 3 7.41 <![CDATA[5.71×10 7 ]]> Example 4 7.36 <![CDATA[5.73×10 7 ]]> Comparative Example 1 7.15 <![CDATA[5.63×10 7 ]]> Comparative Example 2 7.47 <![CDATA[5.70×10 7 ]]> Comparative Example 3 6.12 <![CDATA[5.56×10 7 ]]> The data in the table show that the peel strength of the copper foils obtained in Examples 1 to 4 is between 0.55 and 0.61 N / mm, and the tensile strength is between 195 and 205 MPa, indicating that the copper foils of the dispersion-strengthened copper composite structure obtained in the present invention have excellent mechanical properties; the density of the copper foils obtained in Examples 1 to 4 is 7.26 to 7.41 g / cm 2 The conductivity is 5.71×10 7 ~5.77×10 7 S / m, indicating that the copper foil obtained by the present invention is lighter than pure copper foil and has excellent conductivity. The copper layer thickened by water electroplating in Comparative Example 3 is only 1.5 μm, and the subsequent process increases the dispersed aluminum content in the copper layer through heat treatment, so its density is much smaller than that of each embodiment, and the excessive dispersed aluminum content causes a significant decrease in its conductivity.

[0029] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0030] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure, characterized in that: The steps include: S1. After removing the oxide layer by sandpaper polishing, the aluminum foil with a thickness of 0.03-0.06 μm was added to 90-95 wt % ethanol for washing for 5-10 min, then washed with 5-10 wt % acetic acid for 5-8 min, and finally rinsed with deionized water for 2-3 times, and dried at 40-60 ° C to obtain the pretreated aluminum foil; S2, copper-plating the pretreated aluminum foil on one side by vacuum magnetron sputtering technology, controlling the thickness of the single-sided copper layer to be 30-60 nm, and then thickening the copper layer by 3-5 μm by water electroplating technology to obtain a copper-aluminum composite foil; S3, after rolling and compacting the copper-aluminum composite foil, placing it in a resistance furnace and heating it at 300-400° C. for 2-4 hours to form a copper-aluminum composite foil with a three-layer structure of aluminum / copper-aluminum solid solution / copper; S4, placing the copper-aluminum composite foil into an electrolytic cell, with the copper layer as the negative electrode and the aluminum layer as the positive electrode, and electrolyzing and dissolving the aluminum layer to obtain an extremely thin composite copper layer; S5. Coating a surface treatment agent on the surface of the ultra-thin composite copper layer, and subjecting it to a high-temperature heat treatment at 800-950° C. in an argon atmosphere to form a dispersion-strengthened copper composite foil.

2. The method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure according to claim 1, characterized in that: The vacuum degree controlled by vacuum magnetron sputtering in S2 is less than 2~3×10 -4 MPa, the sputtering power is 50~60W, the working pressure is 0.5~0.6Pa, the aluminum foil temperature is 150~200℃, the atmosphere is either argon or nitrogen, and the target material is pure copper target with a purity of more than 99.999%.

3. The method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure according to claim 1, characterized in that: The copper plating solution in water electroplating in S2 consists of 80-100 g / L copper sulfate, 0.05-0.1 g / L sodium chloride, 0.2-0.5 g / L polyethylene glycol and 90-100 g / L sulfuric acid. The working temperature of water electroplating is 40-50° C., the circulation rate of the copper plating solution is 2-4 L / min, and the current density ranges from 300-500 A / m 2 , the plating time is 30~60s.

4. The method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure according to claim 1, characterized in that: The electrolyte composition of S4 is composed of 60-70 g / L sulfuric acid, 30-50 g / L copper sulfate, 3-6 g / L sodium carboxymethyl cellulose, 20-25 g / L sodium potassium tartrate, 1-2 g / L disodium ethylenediaminetetraacetate and 0.2-0.5 g / L sodium polydisulfide dipropane sulfonate, and the current density range is 100-800 A / m 2 , the electrolytic cell voltage range is 0.5~5V.

5. The method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure according to claim 1, characterized in that: The preparation method of the surface treatment agent in S4 comprises the following steps: S11, adding 0.05-0.06 parts of copper acetate to 50 parts of deionized water, heating in an oil bath to 70-80°C, adding dropwise 20-30 parts of 70-80 g / L sodium hydroxide solution, and finally adding dropwise 5-6 parts of 300 g / L glucose solution, reacting for 2-3 hours, filtering and collecting the solid, and drying at 50-60°C to obtain nano cuprous oxide powder; S12, adding bistrimethylsiloxymethylsilane to deionized water, heating at 70-80°C for 1-2h, adding nano cuprous oxide powder under stirring, controlling the pH to 7.5-8.5, reacting at 70-80°C for 20-24h, filtering and drying to obtain modified nano cuprous oxide powder; S13, dissolving 0.5-0.6 parts of chitosan in 100 parts of deionized water, stirring at 40-50° C. for 1-2 hours, adding 0.5-0.8 parts of modified nano cuprous oxide powder and 0.3-0.5 parts of 1H-benzimidazole-5,6-diol to prepare a surface treatment agent.

6. The method for preparing a high-strength ultra-thin copper foil having a dispersion-strengthened copper composite structure according to claim 1, characterized in that: Preferably, the mass ratio of bistrimethylsiloxymethylsilane to nano cuprous oxide powder in the S12 is 0.5-0.8:

1.

7. A high-strength ultra-thin copper foil with a dispersion-strengthened copper composite structure prepared according to the method for preparing a high-strength ultra-thin copper foil with a dispersion-strengthened copper composite structure according to any one of claims 1 to 6.