Industrial production method of copper foil

Abstract

The present application discloses an industrial production method for copper foil, which belongs to the technical field of preparation and production of electrolytically deposited copper foil. An industrial production method for copper foil includes copper dissolution, electrolytic copper foil, and anti-oxidation treatment; S1, the electrolyte obtained after copper dissolution is passed into an electrolytic cell, and copper foil is obtained after electrolysis; S2, the copper foil is subjected to anti-oxidation treatment; the method for electrolytic copper foil includes the following steps: a mixed solution containing the electrolyte and an organic additive is subjected to an electrochemical reaction to obtain the copper foil; the output current in the electrochemical reaction has a small fluctuation; the small fluctuation is obtained by rectifying and fluctuating an AC power supply; or, the small fluctuation is achieved by outputting a small current pulse through a transistor switching power supply, and multiple waveforms are superimposed. This method uses a small amount of additives, and the power consumption of the power supply used in production is low, which reduces the cost of producing electrolytic copper foil and facilitates large-scale industrial production.

Description

Technical Field

[0001] The present application relates to an industrialized production method of copper foil, belonging to the technical field of electrolytic copper foil production. Background Art

[0002] Electrolytic copper foil is a key material for battery anode production. Reducing its thickness frees up space for increasing the amount of active material, thereby boosting energy density. Furthermore, reducing copper usage improves battery performance and reduces costs. The trend toward thinner and lighter materials places higher demands on copper foil's performance and manufacturing technology. Besides meeting electrical conductivity, corrosion resistance, and low roughness requirements, it must also possess high room-temperature elongation and tensile strength. This increases production complexity and demands continuous advancements in manufacturing technology.

[0003] The existing technology is carried out through continuous electrolysis. The raw foil is prepared by converting the electrolyte into raw foil through electrochemical reaction under direct current conditions of large current (over 30,000A). As the product thickness decreases, in order to ensure the continuous and stable production of defect-free products, the current load of the foil production process must be reduced. For example, the load rate for copper foils above 8μm is above 45,000A, while the load rate for copper foils below 6μm needs to be reduced to below 4.0Ah. On the other hand, the quality requirements for additives are higher. Insufficient or excessive additives can easily lead to adverse effects such as warping, pinholes, and decreased strength and elongation, greatly increasing the process difficulty and production costs.

[0004] Studies have shown that pulses can generate tensile and relaxation stresses in a short period of time, and can introduce a large number of nano-twin structures to improve the mechanical properties of copper foil. However, it has not been applied to production so far. On the one hand, this is because the large current obtained by the pulse method has a large gap in control accuracy and production efficiency compared with the direct current method; on the other hand, the pulse may also affect the incorporation of specific organic additives or cause complex situations such as abnormal segregation at grain boundaries. Summary of the Invention

[0005] According to the first aspect of the present application, a method for industrial production of copper foil is provided. The purpose of the present invention is to overcome the practical problems of the prior art, such as the insufficient mechanical properties and high production difficulty of ultra-thin electrolytic copper foil, by providing a method for producing electrolytic copper foil, including a low-cost additive formulation and a current mode with lower energy consumption. This current mode with lower energy consumption is used instead of a completely DC waveform with higher energy consumption to produce electrolytic copper foil for dual-light lithium-ion batteries. The processed ultra-thin dual-light electrolytic copper foil has both high tensile strength and high elongation (high toughness), while ensuring a high load rate, further improving yield, and reducing processing costs.

[0006] An industrial production method of copper foil, comprising copper dissolving, electrolytic copper foil, and anti-oxidation treatment;

[0007] S1, passing the electrolyte obtained after dissolving copper into an electrolytic cell, and obtaining copper foil after electrolysis;

[0008] S2, performing anti-oxidation treatment on the copper foil;

[0009] The method for electrolytic copper foil comprises the following steps:

[0010] subjecting a mixed solution containing the electrolyte and the organic additive to an electrochemical reaction to obtain the copper foil;

[0011] The output current in the electrochemical reaction has small fluctuations;

[0012] The small fluctuation is obtained by rectifying and fluctuating the AC power supply; or,

[0013] The tiny fluctuation is achieved by outputting tiny current pulses through a transistor switching power supply and superimposing multiple waveforms.

[0014] The output current of a single rectifier is 500A~1500A.

[0015] During production, 5 to 10 single rectifiers with the same waveform are connected in parallel to obtain an output current of 10kA to 150kA.

[0016] The current used in production is 30kA to 60kA.

[0017] Optionally, the small fluctuation is obtained through silicon rectification.

[0018] Optionally, the transistor switching power supply is selected from a high-frequency switching power supply.

[0019] The output current fluctuates slightly around the average current, with a certain amplitude and frequency, but is still a DC current overall. Compared to a pure DC waveform, this waveform has a lower output voltage, resulting in lower energy consumption for the same output current and deposition time.

[0020] Optionally, the fluctuation amplitude of the output current is 6% to 15% of the average current.

[0021] Optionally, the frequency of the output current is 2 Hz to 50 Hz.

[0022] Optionally, the high level ratio of the output current is 50% to 95%.

[0023] Except when the high level ratio is 50%, t Imax ≠t Imin .

[0024] The high level ratio refers to the proportion of the time in which the current is above the average current in a cycle to the time in the cycle.

[0025] Optionally, the waveform of the output current is at least one of a sine wave, a rectangular wave, a triangle wave, and a sawtooth wave DD221041I.

[0026] Optionally, the organic additive is selected from at least three of sodium polydisulfide propane sulfonate (SPS), hydroxyethyl cellulose, polyethylene glycol, polypeptide protein (collagen peptide), and acryloyl urea derivatives.

[0027] The organic additive is added in the form of an aqueous solution.

[0028] Optionally, the solution concentration of the polysodium disulfide propane sulfonate (SPS) is 1 g / L to 10 g / L.

[0029] Optionally, the concentration of the hydroxyethyl cellulose solution is 2.0 g / L to 20.0 g / L.

[0030] Optionally, the concentration of the polyethylene glycol solution is 2.0 g / L to 20.0 g / L; the polyethylene glycol is obtained by mixing polyethylene glycols with molecular weights of 1000, 2000, and 6000.

[0031] Optionally, the concentration of the polypeptide protein (collagen peptide) solution is 2 g / L to 10 g / L.

[0032] Optionally, the solution concentration of the acryloyl urea derivative is 1.0 g / L to 5.0 g / L.

[0033] The additive is added into the anode tank during the foil production step at a flow rate of 1.0 ml / min to 10.0 ml / min.

[0034] Optionally, the flow rate of the sodium polydisulfide bis(propylene sulfonate) SPS solution is 5.0 ml / min to 10.0 ml / min; the flow rate of the hydroxyethyl cellulose HEC solution is 5.0 ml / min to 6.0 ml / min; the flow rate of the polyethylene glycol PEG solution is 5.0 ml / min to 10.0 ml / min; the flow rate of the polypeptide protein (collagen peptide) solution is 5.0 ml / min to 10.0 ml / min, and the flow rate of the acryloyl urea derivative solution is 1.0 ml / min to 5.0 ml / min.

[0035] The type and content of the organic additive can be adsorbed under the action of the waveform current.

[0036] Optionally, the conditions for the electrochemical reaction are as follows:

[0037] The current density is 55A / dm 2 ~75A / dm 2 .

[0038] Optionally, in the electrochemical reaction, the titanium roller serves as the cathode and the titanium plate with the titanium-iridium-tantalum coating serves as the anode.

[0039] Optionally, the cathode roller linear speed is 2 m / min to 10 m / min.

[0040] Optionally, the flow rate of the electrolyte is 20m 3 / h~50m 3 / h.

[0041] Optionally, the roughness of the titanium cathode is as follows:

[0042] Ra is 0.2μm~0.3μm;

[0043] Rz is 2.0μm~2.5μm.

[0044] Optionally, the grain size of the titanium cathode surface is 10-12 levels.

[0045] Optionally, the copper dissolving process includes the following steps:

[0046] Sulfuric acid is sprayed on a mixture containing copper material, and high-temperature compressed air is introduced to dissolve the copper material to form a copper solution.

[0047] Optionally, the content of copper ions is 90 g / L.

[0048] Optionally, the concentration of H2SO4 is 100g / L to 120g / L.

[0049] Optionally, the chloride ion content is 10 mg / L to 15 mg / L.

[0050] Optionally, the temperature is 50°C to 58°C.

[0051] Optionally, the electrolyte undergoes multi-stage filtration before entering the anode tank.

[0052] Optionally, the anti-oxidation treatment is carried out in an anti-oxidation tank.

[0053] Optionally, the anti-oxidation solution is selected from aqueous chromic anhydride solutions.

[0054] The production process of electrolytic copper foil should also include steps such as pickling, water washing, and drying after anti-oxidation treatment.

[0055] (1) Copper dissolving and electrolyte preparation: Copper material is placed in a copper dissolving tank, sprayed with sulfuric acid, and introduced with high-temperature compressed air to dissolve the copper material into a copper solution. After multi-stage filtration, the solution enters the anode tank. The copper ion concentration in the electrolyte is controlled at 90g / L, the H2SO4 content is 100-120g / L, and the chloride ion concentration is 10-15mg / L.

[0056] (2) Adding additives: Add the additive aqueous solution to the anode tank at a flow rate of 1.0 to 10.0 ml / min. The flow rate of the sodium polydisulfide bis(propylene sulfonate) SPS solution is 5.0 to 10.0 ml / min, the flow rate of the hydroxyethyl cellulose HEC solution is 5.0 to 6.0 ml / min, the flow rate of the polyethylene glycol PEG solution is 5.0 to 10.0 ml / min, the flow rate of the polypeptide protein (collagen peptide) solution is 5.0 to 10.0 ml / min, and the flow rate of the acryloyl urea derivative solution is 1.0 to 5.0 ml / min.

[0057] (3) Electrolytic foil: Select silicon rectifier power supply or high-frequency switching power rectifier to provide the required small fluctuation DC, 30000-60000A. Specific parameters: Fluctuation frequency is 2Hz ( Figure 1 T=500ms); the difference between the peak and valley current is 2% of the average current ((I max -I min ) / I0 is 2%); the high level ratio is 90% (t Imax / T=90%).

[0058] The process conditions for controlling electrolytic foil production are current density 55~75A / dm 2 , the cathode roller linear speed is 2~10m / min, the flow rate of copper sulfate electrolyte in the electrolytic cell is 20~50m 3 / h.

[0059] (4) The anti-oxidation treatment is carried out in an anti-oxidation tank. The anti-oxidation solution may be a chromic anhydride aqueous solution, and the parameters are controlled to meet the process requirements.

[0060] The copper foil was cut into pieces with a width of 0.5 inches using a double-edged cutting knife (JDC, THWING-ALBERT), and then the tensile properties of the copper foil were tested using a single tensile testing machine (Dynamics, LD22.502).

[0061] The surface roughness and glossiness of the copper foil were recorded using a roughness meter (Marfurf, PS10) and a micro gloss meter (BYK4563).

[0062] The warpage test method is as follows: cut a 200mm×200mm copper foil, place it horizontally with the rough side facing up, test the height of the four corners bending upward, and take the maximum value as the warpage value of the copper foil, in mm.

[0063] The beneficial effects of this application include:

[0064] 1) The present application provides an industrialized production method for copper foil. This method uses a small amount of additives and has low power consumption, thereby reducing the cost of producing electrolytic copper foil. In addition, compared with a completely direct current, the slightly fluctuating waveform has the advantage of reducing or eliminating the need to reduce the current load in the foil production process when producing copper foil of the same thickness specification, which is equivalent to increasing production capacity. Therefore, this process is very advantageous for the actual production of extremely thin electrolytic copper foil. The copper foil obtained by this method has better overall performance than using current fluctuation or the additive formula alone.

[0065] 2) The present application provides an industrial production method for copper foil, wherein the electrolytic copper foil for dual-light lithium-ion batteries prepared by the method has a unit area weight of 54±2g / m 2 The matte surface roughness (Rz) is 1.0 μm to 2.0 μm; the matte surface brightness is 120 GU to 300 GU; the room-temperature tensile strength of the electrolytic copper foil with a nominal thickness of 4 μm to 6 μm is 400 MPa to 600 MPa; the yield strength is 380 MPa to 560 MPa; and the elongation is 10% to 18%. The copper foil exhibits almost no degradation in mechanical properties when stored at room temperature for more than 7 days or baked in a 150°C oven for 10 minutes, i.e., the degradation in tensile strength, yield strength, and elongation does not exceed 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 The sine wave waveform diagram of this application is obtained by a silicon rectifier power supply, where I0 refers to the average current output by the rectifier, I max Refers to the maximum current, I min Refers to the minimum current value, (I max -I min ) / I0 is 6% to 15%.

[0067] Figure 2 This is a schematic diagram of the rectangular wave waveform of this application, which is obtained by connecting multiple rectifiers in parallel through a high-frequency switching pulse power supply. The solid line represents the final waveform, and the dotted line represents a single waveform. The final waveform is obtained by superposition. Among them, I0 refers to the average current output by the rectifier, I max Refers to the maximum current, I min Refers to the minimum current value. The time it takes for the current signal to rise from a low value to a high value and then fall back is called the pulse rise time Δt1 and the pulse decay time Δt2, respectively. The time it takes for the initial signal to reach the initial current setting value from 0 is called the ramp time, recorded as Δt0. DETAILED DESCRIPTION

[0068] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0069] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0070] Example 1

[0071] (1) Copper dissolving and electrolyte preparation: Copper material is placed in a copper dissolving tank, sprayed with sulfuric acid, and introduced with high-temperature compressed air to dissolve the copper material into a copper solution. After multi-stage filtration, the solution enters the anode tank. The copper ion concentration in the electrolyte is controlled at 90g / L, the H2SO4 content is 120g / L, and the chloride ion concentration is 15mg / L.

[0072] (2) Adding additives: Additive aqueous solutions were continuously introduced into the anode tank at a certain flow rate, including: sodium polydisulfide propane sulfonate SPS solution at a flow rate of 10.0 ml / min, polyethylene glycol PEG solution at a flow rate of 10.0 ml / min, polypeptide protein (collagen peptide) solution at 6.0 ml / min, and acryloyl urea derivative solution at 5.0 ml / min.

[0073] (3) Electrolytic foil: Select silicon rectifier power supply to provide the required small fluctuation DC, 30kA. Specific parameters: Fluctuation frequency 2Hz ( Figure 1 T=500ms); the difference between the peak and valley current is 6% of the average current ((I max -I min ) / I0 is 6%); the high level ratio is 80% (t Imax / T=80%).

[0074] The process conditions for controlling electrolytic foil production are a current density of 60A / dm 2 , the cathode roller linear speed is 6m / min, the flow rate of copper sulfate electrolyte in the electrolytic cell is 50m 3 / h.

[0075] (4) Anti-oxidation treatment: It is carried out in an anti-oxidation tank. The anti-oxidation solution can be a chromic anhydride aqueous solution, and the parameters are controlled to meet the process requirements.

[0076] Example 2

[0077] The other steps are the same as those in Example 1, except that the silicon rectifier power supply is changed to 10 3000A high-frequency switching power supplies connected in parallel, and the output current parameter of each power supply is a fluctuation frequency of 0.5Hz ( Figure 2 T=2000ms); the difference between the peak and valley current is 10% of the average current ((I max -I min ) / I0 is 10%); high level ratio is 90% (t Imax / T=90%) to obtain the final copper foil.

[0078] Comparative Example 1

[0079] The other steps were the same as those in Example 2, except that the power supply mode was changed to a completely direct current mode, with 10 3000A high-frequency switching power supplies connected in parallel to obtain the final copper foil.

[0080] Comparative Example 2

[0081] The remaining steps were the same as in Example 1, with only the additive amounts being changed. The flow rates of the poly(sodium disulfide propylene sulfonate) solution (SPS) were 20.0 ml / min, the polyethylene glycol (PEG) solution was 20.0 ml / min, the polypeptide protein (collagen peptide) solution was 15.0 ml / min, and the acryloyl urea derivative solution was 5.0 ml / min. The final copper foil was obtained.

[0082] Analysis example

[0083] The copper foils obtained in Examples 1 and 2 were tested for tensile properties, surface roughness, glossiness, pinholes, surface discoloration before and after baking, and curling. The testing methods were in accordance with GB / T 228.1-201 Tensile Tests on Metallic Materials - Part 1: Room Temperature Test Methods and GB / T 29847-2013 Test Methods for Copper Foil for Printed Circuit Boards.

[0084] Example 1: Output voltage is 4.0V~4.2V;

[0085] Copper foil strength: 498MPa, yield strength 466MPa, elongation 12.1%; number of pinholes: 0-1 / cm 2 ;Warping is less than 2mm.

[0086] Example 2: Output voltage is 3.8V~4.0V;

[0087] Copper foil strength: 598MPa, yield strength 466MPa, elongation 14.5%;

[0088] Number of pinholes: 0 to 1 per cm 2 ;Warping is less than 2mm.

[0089] Comparative Example 1: Output voltage is 4.2V~4.5V;

[0090] Copper foil strength: 402MPa, yield strength 371MPa, elongation 5.1%;

[0091] Number of pinholes: 2 to 6 per cm 2 ; Warping is higher than 2mm and lower than 8mm.

[0092] Comparative Example 2: Output voltage is 3.8V~4.0V;

[0093] Copper foil strength: 332MPa, yield strength 304MPa, elongation 6.8%; number of pinholes: 1 to 3 / cm 2 ;Warping less than 5mm.

[0094] Under the same current conditions, fluctuating current consumes less energy than pure direct current, significantly reducing production costs while ensuring output. Copper foil produced using fluctuating current has lower warpage because twin boundaries facilitate the release of residual stress in the copper foil.

[0095] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An industrial production method of copper foil, characterized in that: Including copper dissolution, electrolytic copper foil, and anti-oxidation treatment; S1, passing the electrolyte obtained after dissolving copper into an electrolytic cell, and obtaining copper foil after electrolysis; S2, performing anti-oxidation treatment on the copper foil; The method for electrolytic copper foil comprises the following steps: subjecting a mixed solution containing the electrolyte and the organic additive to an electrochemical reaction to obtain the copper foil; The output current in the electrochemical reaction is a direct current with slight fluctuations; The small fluctuation is obtained by rectifying and fluctuating an AC power supply, or the small fluctuation is achieved by outputting a small current pulse through a transistor switching power supply and superimposing multiple waveforms; The output current fluctuation range is 6% to 15% of the average current; The frequency of the output current is 2 Hz ~ 50 Hz; The high level ratio of the output current is 80% to 95%; The high level ratio refers to the proportion of the time in which the current is above the average current in a cycle; The organic additive is selected from at least three of sodium polydisulfide dipropane sulfonate, hydroxyethyl cellulose, polyethylene glycol, polypeptide protein, and acryloyl urea derivatives; The organic additive is added in the form of its aqueous solution; The concentration of the solution of sodium polydisulfide propane sulfonate is 1 g / L to 10 g / L; The concentration of the hydroxyethyl cellulose solution is 2.0 g / L to 20.0 g / L; The concentration of the polyethylene glycol solution is 2.0 g / L to 20.0 g / L; the polyethylene glycol is obtained by mixing polyethylene glycols with molecular weights of 1000, 2000, and 6000; The concentration of the polypeptide protein solution is 2 g / L to 10 g / L; The concentration of the solution of the acryloyl urea derivative is 1.0 g / L to 5.0 g / L; The additive is added into the anode tank during the foil production step; The flow rate of sodium poly (sodium disulfide) bis(propylene sulfonate) SPS solution is 5.0 ml / min ~ 10.0 ml / min; the flow rate of hydroxyethyl cellulose (HEC) solution is 5.0 ml / min ~ 6.0 ml / min; the flow rate of polyethylene glycol (PEG) solution is 5.0 ml / min ~10.0 ml / min; the flow rate of polypeptide protein solution is 5.0 ml / min ~ 10.0 ml / min, and the flow rate of acryloyl urea derivative solution is 1.0 ml / min ~ 5.0 ml / min.

2. The industrial production method according to claim 1, characterized in that The small fluctuation is obtained through silicon rectification.

3. The industrial production method according to claim 1, characterized in that The transistor switching power supply is selected from a high-frequency switching power supply.

4. The industrial production method according to claim 1, characterized in that The waveform of the output current is at least one of a sine wave, a rectangular wave, a triangle wave, and a sawtooth wave.

5. The industrial production method according to claim 1, characterized in that: The conditions for the electrochemical reaction are as follows: The current density is 55 A / dm 2 ~ 75 A / dm 2 .

6. The industrial production method according to claim 1, characterized in that In the electrochemical reaction, the titanium / roller is used as the cathode and the titanium plate with titanium, iridium and tantalum coating is used as the anode.

7. The industrial production method according to claim 1, characterized in that The cathode roller linear speed is 2 m / min ~ 10 m / min.

8. The industrial production method according to claim 1, characterized in that The flow rate of electrolyte is 20 m 3 / h ~ 50m 3 / h.

9. The industrial production method according to claim 1, characterized in that The roughness of the titanium cathode is as follows: Ra is 0.2 μm ~ 0.3 μm; Rz is 2.0 μm ~ 2.5 μm.

10. The industrial production method according to claim 1, characterized in that: The grain size of the titanium cathode surface is 10~12 levels.

11. The industrial production method according to claim 1, characterized in that: The copper dissolving step comprises the following steps: Sulfuric acid is sprayed on a mixture containing copper material, and high-temperature compressed air is introduced to dissolve the copper material to form a copper solution.

12. The industrial production method according to claim 11, characterized in that: The copper ion content is 90 g / L.

13. The industrial production method according to claim 11, characterized in that: The concentration of H2SO4 is 100 g / L ~120 g / L.

14. The industrial production method according to claim 11, characterized in that: The chloride ion content is 10 mg / L ~15 mg / L.

15. The industrial production method according to claim 11, characterized in that: The temperature is 50℃ ~ 58℃.

16. The industrial production method according to claim 11, characterized in that: The electrolyte undergoes multi-stage filtration before entering the anode tank.

17. The industrial production method according to claim 1, characterized in that: The anti-oxidation treatment is carried out in an anti-oxidation tank.

18. The industrial production method according to claim 1, characterized in that: The anti-oxidation solution is selected from aqueous chromic anhydride solution.

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