A method for controlling the grain size distribution of electrolytic copper foil

Abstract

This invention discloses a method for controlling the grain size distribution of electrolytic copper foil, belonging to the field of electrolytic copper foil technology, to address the problem of the lack of relevant methods in the prior art for increasing the crystallization nucleation rate through system perturbation. The method includes constructing an electrolytic green foil system, electrolyzing the green foil, controlling the grain size distribution during production, cleaning, drying, and winding the green foil. When applied to production, this invention does not significantly alter the original process, does not change the composition of the electrolyte, does not cause mechanical damage to the cathode roller and anode plate, and does not reduce the efficiency of copper foil production. Only slight modifications are needed within the cathode roller to increase the system perturbation on the cathode roller surface, and the degree of increase in system perturbation can be achieved by adjusting the power of the eccentric wheel according to product specifications.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic copper foil technology, specifically relating to a method for controlling the grain size distribution of electrolytic copper foil. Background Technology

[0002] In recent years, the development of high technology has led to increasingly higher demands and quality requirements for electrolytic copper foil. Especially in power batteries and energy storage batteries, copper foil, as the most widely used negative electrode current collector, is playing an increasingly important role. As battery energy density increases, the requirements for copper foil also become more stringent. On the one hand, copper foil thickness is decreasing; currently, 6-micron copper foil, and even thinner 4.5-micron copper foil, are being promoted downstream. However, while the copper foil is becoming thinner, its tensile strength must be maintained to meet the requirements of continuous coating downstream. On the other hand, the elongation, warpage, and flexibility of copper foil are also key performance indicators when used as current collectors. Both tensile strength and flexibility are directly related to the crystal texture morphology of the copper foil. Therefore, controlling the crystal texture morphology and grain size distribution of copper foil during the production process is of great significance.

[0003] Typically, the deposition process in the electrolytic copper foil production process can be divided into two stages: the first stage involves the rapid formation of numerous crystal nuclei on the cathode roller surface, which then grow into small grains; the second stage occurs as the copper ion concentration in the double layer at the foil-solution interface gradually decreases, making it difficult for crystal nuclei to form. The low-concentration copper ions, after reduction, are almost entirely used for grain growth, resulting in larger columnar crystals. The formation of these larger columnar crystals has a significant negative impact on the tensile strength, flexibility, and other physical properties of the copper foil.

[0004] To address this issue, existing technologies typically employ two approaches: One involves introducing additives of varying compositions and concentrations into the electrolyte to regulate crystal growth or nucleation rates, thereby altering the crystal texture. While this method increases the nucleation rate and reduces grain size to some extent, a negative consequence is reduced purity of the electrolytic copper foil due to additive residue, increased cost, and more uncontrollable factors. The other approach is to increase the electrolyte diffusion rate through physical methods, such as adding ultrasonic vibration elements. While this method does increase the electrolyte diffusion rate, the industry's current focus on increasing current density to maximize single-unit capacity results in insufficient copper ion concentration in most areas of the electrolytic cell. The increased copper ion diffusion from ultrasonic vibration primarily accelerates grain growth, failing to meet ideal nucleation conditions, thus having little impact on the nucleation rate. Furthermore, ultrasonic vibration can cause the active material on the anode plate surface to detach, reducing the anode plate's lifespan.

[0005] Researchers have discovered that the formation of copper foil crystal nuclei is not solely determined by the solution system but is also influenced by system disturbances. These disturbances encompass various aspects of the entire system, including the environment, equipment, and fluid erosion, and remain largely constant under stable production conditions. Current technologies have focused on adjusting techniques to control the crystal growth rate under the condition of constant system disturbances. However, neither the additives nor the increased copper ion supply have considered the impact of system disturbances.

[0006] Researchers also discovered that increasing system perturbation while keeping the solution supply and current constant can increase the rate of crystal nucleation, thus preventing the grains from growing continuously and reaching their full size. However, existing technologies lack methods for increasing system perturbation. Therefore, developing a new method that does not reduce production capacity, ensures stable production, and allows for easy control of grain size distribution has become a major challenge in the research on controlling crystal texture morphology and grain size distribution in copper foil production. Summary of the Invention

[0007] The purpose of this invention is to provide a method for controlling the grain size distribution of electrolytic copper foil, so as to solve the problem that there is a lack of relevant methods in the prior art to increase the crystallization nucleation rate through system perturbation.

[0008] To solve the above problems, the technical solution of the present invention is as follows:

[0009] A method for controlling the grain size distribution of electrolytic copper foil, characterized by the following steps:

[0010] Step A: Construct an electrolytic foil system;

[0011] A vibratory electric motor assembly is installed on the intermediate support shaft of the cathode roller of the existing equipment. The vibratory electric motor assembly includes an electric motor and an eccentric wheel driven by it.

[0012] Then, following the steps in the existing technology, install the anode plate and cathode roller in the green foil electrolytic cell, and introduce copper sulfate electrolyte into the green foil electrolytic cell to construct an electrolytic green foil system;

[0013] Step B: Electrolysis of raw foil;

[0014] Electrolytic foil production is carried out by controlling the current between the cathode roller and the anode plate, the linear velocity of the cathode roller, and the electrolyte supply flow rate.

[0015] in:

[0016] Step C: Grain size distribution control during production;

[0017] During production, the electric motor is turned on, and the speed of the eccentric wheel is controlled by adjusting the input power of the electric motor, according to the formula... It can be seen that the input power is used to regulate the rotational speed n of the eccentric wheel so that different rotational speeds result in different moments of inertia, which in turn lead to different vibration frequencies. The eccentric wheel drives the cathode roller surface to resonate, changing the influence weight of foil surface disturbance on the nucleation of copper foil grains.

[0018] Step D: Cleaning, drying, and winding of the raw foil;

[0019] After the raw foil leaves the electrolyte as the cathode roller rotates, it undergoes four steps: cleaning with dilute sulfuric acid solution, squeezing acid with an acid squeezing roller, rinsing with pure water, and squeezing water with a water squeezing roller. Then, the surface of the copper foil is dried, and finally, the copper foil is stably wound up by controlling a certain tension.

[0020] Furthermore, in step A, the eccentric wheel and the electric motor are built into the center of the intermediate support shaft. The rated voltage of the electric motor can be 12 V, 24 V, 36 V, 48 V, 220 V, 380 V, or 6000 V, with insulation class B / F / H and input power of 0.1-10 KW.

[0021] Furthermore, in step A, the preferred input power of the electric motor is 1.75 KW.

[0022] Furthermore, in step B, the current density between the cathode roller and the anode plate is 10-50 kA, the linear velocity of the cathode roller is controlled at 1-6 m / s, and the electrolyte supply flow rate is 30-60 m³ / s. 3 / h.

[0023] Furthermore, the preferred parameters between the cathode roller and the anode plate in step B are: current density 42 kA, linear velocity 2.1 m / s, and electrolyte flow rate 41.5 m³ / s. 3 / h.

[0024] Furthermore, in step A, the cathode roller is a titanium roller, the anode plate is a titanium plate with a surface coated with sintered iridium oxide, and the copper sulfate electrolyte introduced into the electrolytic cell is acidic copper sulfate.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) This invention breaks through the traditional approach of controlling crystal texture morphology and grain size distribution, bypassing the methods of adding additives and increasing copper ion supply. It utilizes the technical breakthroughs made by researchers in the background art, employing a physical method of embedding an eccentric wheel and an electric motor in the center of the intermediate support shaft to increase system disturbance. This system disturbance increases the rate of crystal nucleation, thereby achieving control over grain size distribution. Specifically, during the deposition of the foil, system disturbance disrupts the continuous growth of the grains, inducing crystal distortion and forming new crystal nuclei, thus indirectly controlling the grain size and achieving quantitative control of grain size in the copper foil. In other words, this method of increasing system disturbance can promote crystal nucleus formation even under conditions of insufficient copper ion supply and no additives, avoiding the impact of additive residues on the properties of the copper foil. It also simplifies the control of additives in the production process, reducing production costs.

[0027] (2) When applied to production, this invention does not make significant changes to the original process, does not adjust or change the composition of the electrolyte, will not cause mechanical damage to the cathode roller and anode plate, and will not reduce the efficiency of copper foil production. Only a slight modification to the cathode roller is needed to increase the system disturbance on the cathode roller surface, and the degree of increase in system disturbance can be achieved by adjusting the power of the eccentric wheel according to the product specification requirements.

[0028] (3) The method of the present invention is simple and convenient, green and pollution-free. After one-time modification and installation, its cost is negligible. It does not increase production energy consumption and cost. It can easily and freely achieve the production of high-end copper foil with high tensile strength and flexibility by controlling the grain size. It can greatly improve the product category pattern of copper foil production in my country and the production efficiency of enterprises. It is very suitable for widespread application in industrial production. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of an electrolytic cell in a method for controlling the grain size distribution of electrolytic copper foil;

[0030] Figure 2 This is a schematic diagram of the electric motor and eccentric wheel installed inside the cathode roller in a method for controlling the grain size distribution of electrolytic copper foil.

[0031] Figure 3 This is a diagram showing the crystal orientation distribution of the copper foil sample in the example.

[0032] Figure 4 This is a diagram showing the crystal orientation distribution of the copper foil sample used as a control.

[0033] The attached diagram is labeled as follows: 1-Electrolytic cell; 2-Anode plate; 3-Intermediate support shaft; 4-Cathode roller; 5-Electric motor; 6-Eccentric wheel. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a 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 those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Therefore, the following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0036] Example 1

[0037] like Figure 1-2 As shown, a method for controlling the grain size distribution of electrolytic copper foil includes the following steps:

[0038] Step A: Construct an electrolytic foil system;

[0039] A vibratory electric motor assembly is installed on the intermediate support shaft 3 of the cathode roller 4 of the existing equipment. The vibratory electric motor assembly includes an electric motor 5 and an eccentric wheel 6 driven by it.

[0040] Then, following the steps in the existing technology, install the anode plate 2 and the cathode roller 4 in the green foil electrolytic cell 1, and introduce copper sulfate electrolyte into the green foil electrolytic cell 1 to construct an electrolytic green foil system;

[0041] Step B: Electrolysis of raw foil;

[0042] The current between the cathode roller 4 and the anode plate 2 is controlled at 30 kA, the linear velocity of the cathode roller 4 is 3.6 m / s, and the Cu in the electrolyte is controlled at... 2+ The electrolyte concentration was 95 g / L, the sulfuric acid concentration was 110 g / L, and the electrolyte supply flow rate was 35.2 m³ / L. 3 / h, electrolytic foil production is carried out.

[0043] Step C: Grain size distribution control during production;

[0044] During the production process, the electric motor 5 is turned on, and the eccentric wheel 6 is rotated by adjusting the electric motor 5. The eccentric wheel 6 drives the cathode roller 4 to resonate, changing the influence weight of foil surface disturbance on the nucleation of copper foil grains. The rated voltage is set to 380 V, the insulation class is F, and the input power is 1.5 KW.

[0045] Step D: Cleaning, drying, and winding of the raw foil;

[0046] After the raw foil leaves the electrolyte as the cathode roller 4 rotates, it undergoes four steps: cleaning with dilute sulfuric acid solution, squeezing acid with an acid squeezing roller, rinsing with pure water, and squeezing water with a water squeezing roller. Then, the surface of the copper foil is dried, and finally, the copper foil is stably wound up by controlling a certain tension.

[0047] Comparison Example

[0048] Produced using conventional methods, the difference from Example 1 is as follows:

[0049] Step C is omitted in terms of the electric motor 5 driving the eccentric wheel 6, i.e., the electric motor 5 is not turned on, and other parameters remain unchanged.

[0050] EBSD (electron backscattering diffraction) analysis was performed on the samples produced in Example 1 and Control Example 1 to obtain the crystal orientation distribution maps of the two copper foil samples, as shown below. Figure 3 and Figure 4 As shown, it can be seen that:

[0051] The first stage of copper foil deposition in the comparative example is basically the same as that in Example 1, with relatively small grains. The main reason for this phenomenon is that the initial crystallization is induced by the metal crystallization morphology on the cathode roller surface. However, careful comparative analysis revealed that the grain size in the comparative example is larger, while the grain size in the example is smaller. This indicates that by using the method disclosed in this patent to increase system disturbance, it can promote nucleation and reduce grain size at the very beginning of foil crystallization.

[0052] In the second stage of copper foil growth, larger columnar crystals, up to 10 μm in length, were grown in the control example, while no columnar crystals were generated in Example 1, and the grain size was significantly reduced.

[0053] Therefore, it can be concluded that by increasing system perturbation using the method disclosed in this invention, the nucleation rate during copper foil crystallization can be significantly increased, and the grain size distribution can be reduced.

Claims

1. A method for controlling the grain size distribution of electrolytic copper foil, characterized in that: The method consists of the following steps: Step A: Construct an electrolytic foil system; A set of vibratory electric motor assembly is installed on the intermediate support shaft (3) of the cathode roller (4) of the existing equipment. The vibratory electric motor assembly includes an electric motor (5) and an eccentric wheel (6) driven by it. The eccentric wheel (6) and the electric motor (5) are built into the center of the intermediate support shaft (3). The rated voltage of the electric motor (5) can be 12V, 24V, 36V, 48V, 220V, 380V, or 6000V, with insulation class B / F / H and input power of 0.1-10KW. Then, following the steps in the prior art, install the anode plate (2) and the cathode roller (4) in the green foil electrolytic cell (1), and introduce copper sulfate electrolyte into the green foil electrolytic cell (1) to construct an electrolytic green foil system; Step B: Electrolysis of raw foil; Electrolytic foil production is carried out by controlling the current between the cathode roller (4) and the anode plate (2), the linear velocity of the cathode roller (4), and the electrolyte supply flow rate; the current density between the cathode roller (4) and the anode plate (2) is 10-50kA, the linear velocity of the cathode roller (4) is controlled to be 1-6m / s, and the electrolyte supply flow rate is 30-60m³ / s. 3 / h; in: Step C: Grain size distribution control during production; During the production process, the electric motor (5) is turned on, and the speed of the eccentric wheel (6) is controlled by adjusting the input power of the electric motor (5). The eccentric wheel (6) drives the cathode roller (4) to resonate, changing the influence weight of foil surface disturbance on the nucleation of copper foil grains. Step D: Cleaning, drying, and winding of the raw foil; After the raw foil leaves the electrolyte as the cathode roller (4) rotates, it undergoes four steps: cleaning with dilute sulfuric acid solution, squeezing acid with an acid squeezing roller, rinsing with pure water, and squeezing water with a water squeezing roller. Then, the surface of the copper foil is dried, and finally, the copper foil is stably wound up by controlling a certain tension.

2. The method for controlling the grain size distribution of electrolytic copper foil as described in claim 1, characterized in that: The input power of the electric motor (5) in step A is 1.75KW.

3. The method for controlling the grain size distribution of electrolytic copper foil as described in claim 1, characterized in that: The parameters between the cathode roller (4) and the anode plate (2) in step B are: current density 42kA, linear velocity 2.1m / s, and electrolyte flow rate 41.5m³ / s. 3 / h.

4. The method for controlling the grain size distribution of electrolytic copper foil as described in claim 1, characterized in that: In step A, the cathode roller (4) is a titanium roller, the anode plate (2) is a titanium plate with sintered iridium oxide coated on its surface, and the copper sulfate electrolyte introduced into the electrolytic cell (1) is acidic copper sulfate.

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