Electrochemical method for preparing microporous copper foil

Abstract

The invention discloses an electrochemical method for preparing a microporous copper foil. The electrochemical method comprises the following specific steps: preparing a water-soluble additive to form a solution A; preparing a salt solution B with a certain concentration; uniformly mixing the solution A and the solution B according to a certain proportion to serve as an electrolyte C of an electrochemical method; taking an original copper foil D as an anode, taking a conductive material E as a cathode, and immersing into the electrolyte C for electrolysis; and after electrolysis, the D is taken out, cleaned and aired, and the microporous copper foil F is obtained. And the pore-forming size and density of the product can be adjusted, burrs and other defects do not exist, and different application requirements are met.

Description

Technical Field

[0001] The invention belongs to the technical field of battery materials, and in particular relates to an electrochemical method for preparing microporous copper foil. Background Art

[0002] Microporous copper foil is a secondary process based on the original copper foil, which is made by mechanical processing or other processing methods. At the same time, due to the existence of microporous structure, when used as a current collector of lithium-ion batteries, compared with traditional copper foil, it has the advantages of increasing battery specific energy, improving rate performance, reducing battery internal resistance, and improving copper foil surface adhesion.

[0003] As the demand for energy storage cell single-cell capacity continues to increase, energy storage cell companies have launched large cells with more than 280Ah. However, the increase in size and surface density of these large cells also brings some challenges. These include the problem of poor electrolyte infiltration in the center area of ​​the cell, and the increase in surface density leading to serious attenuation of the cell rate performance. The introduction of microporous copper foil has significantly improved the power performance of the battery: it can effectively shorten the transmission path of lithium ions, thereby improving the power output capacity of the cell. In traditional foil batteries, lithium ions mainly diffuse to the pole ear end in a two-dimensional direction, while microporous copper foil transforms the diffusion path of lithium ions into three-dimensional all-round penetration after passing through the through holes of the foil. At the same time, by increasing the contact surface with the positive and negative electrode materials between the pores, the migration radius of lithium ions is effectively reduced, further improving the power performance of the cell.

[0004] In addition, microporous copper foil can significantly improve production efficiency and consistency, improve the electrolyte infiltration rate by 300%, shorten the aging time of the battery cell, ensure uniform infiltration of the battery cell, and significantly improve the consistency and manufacturing yield of the battery cell. It also improves the safety of the battery cell, effectively avoiding problems such as lithium precipitation and lithium dendrites caused by the drying of the electrolyte in the middle part of the battery cell. At the same time, microporous copper foil increases the life of the battery cell, and by improving adhesion, it prevents the increase in interfacial impedance and lithium ion power loss caused by the shedding of active substances in the later stage. Finally, the lightweight design of microporous copper foil also effectively improves the energy density of the battery cell, further promoting the development and application of energy storage battery technology.

[0005] Microporous copper foil is an important current collector for batteries and supercapacitors in the field of electrochemical energy storage. Traditional methods for preparing microporous copper foil have many disadvantages, such as mechanical punching is prone to burrs, laser punching is prone to oxidation, and traditional chemical etching steps are cumbersome, time-consuming, and costly. These problems limit the widespread application and performance optimization of microporous copper foil in industrial production.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide an electrochemical method for preparing microporous copper foil, so as to overcome the problem of low pore-forming efficiency in the prior art.

[0008] To achieve the above object, the present invention provides an electrochemical method for preparing microporous copper foil, the specific steps are:

[0009] a. preparing a water-soluble additive to form a solution A, wherein the water-soluble additive is one of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, carboxymethyl chitosan, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate), and polyaniline;

[0010] b. Prepare a salt solution B of a certain concentration; the salt solution B is one or more of potassium sulfate, copper chloride, copper sulfate, and ferric chloride, and the concentration is 0.01 mol / L to 1 mol / L;

[0011] c. Mixing solution A and solution B in a certain proportion to form electrolyte C for electrochemical method;

[0012] d. The original copper foil D is used as the anode and the conductive material E is used as the cathode. They are immersed in the electrolyte C for electrolysis. The electrolysis current is 0.01A / dm 2 ~30A / dm 2 , the electrolysis time is 1s to 20min, the temperature is 20 to 70°C; the electrode E is one of platinum, carbon, titanium, stainless steel, copper, platinum, gold, silver, and nickel;

[0013] e. After electrolysis, D is taken out, cleaned and dried to obtain microporous copper foil F.

[0014] When copper foil is immersed in electrolyte, additive molecules can be adsorbed on the surface of copper foil. Electron-donating functional groups of additives with larger molecular weight, such as hydroxyl, amino, carboxyl, and thiol, interact with the 3d empty orbital of copper and evenly cover the surface of copper. During electrolysis, copper foil acts as an anode. Under the action of applied current / voltage, copper loses electrons to generate copper ions, and the additive covering effect on a small part of the surface of copper foil is destroyed, thereby generating holes. Microporous copper foil with different pore sizes and pore structures can be obtained by controlling the type and molecular weight of the polymer, as well as the composition of the electrolyte, the current density, and the duration of electrolysis. Polymer molecular weight and current density can affect the pore density, while the composition of the electrolyte and the duration of electrolysis can affect the pore size and depth.

[0015] Preferably, in the above technical solution, the micropore size is 0-150μm, including blind holes and through holes; blind hole copper foil means that the holes on the copper foil do not penetrate the entire foil, but only form holes of a certain depth on the surface; through hole copper foil means holes that penetrate the foil deeply.

[0016] Preferably, in the above technical solution, the copper foil is electrolytic copper foil or rolled copper foil.

[0017] Preferably, in the above technical solution, the conductive electrode E may be in the form of a plate or a mesh.

[0018] Preferably, in the above technical solution, in step d, the method of applying current or voltage can be constant current, constant voltage, periodic switching current, cyclic voltammetry or pulse electrolysis.

[0019] Preferably, in the above technical solution, in step d, the electrolyte may be static or dynamic, and the flow mode of the dynamic electrolyte may be air disturbance, circulating pump, stirring, etc.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) Efficient hole forming: faster than traditional physical methods and laser drilling, reducing production cycle.

[0022] (2) Precise control: The hole forming accuracy can reach several microns to tens of microns, reducing mechanical damage and improving product quality.

[0023] (3) Multi-dimensional performance improvement: It can enhance the bonding effect between microporous copper foil and electrode materials, thereby improving the charge and discharge rate performance and energy density of batteries and supercapacitors, which is beneficial to the performance optimization of batteries and supercapacitors.

[0024] (3) Wide adaptability: The hole size and density of the product can be adjusted without defects such as burrs to meet different application requirements.

[0025] Through these advantages, the electrochemical processing method developed in this patent can effectively overcome many limitations of traditional preparation methods and promote the application and development of microporous copper foil in the fields of batteries and supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Diagram of the steps of the electrochemical method for preparing microporous copper foil. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0028] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0029] An electrochemical method for preparing microporous copper foil, the copper foil is electrolytic copper foil or rolled copper foil, the micropore size is 0-150μm, including blind holes and through holes. Blind hole copper foil means that the holes on the copper foil do not penetrate the entire foil material, but only form holes of a certain depth on the surface. Through hole copper foil means holes that penetrate the foil material deeply.

[0030] The method for preparing the microporous copper foil as described above comprises the following specific steps:

[0031] a. Prepare water-soluble additive solution A, which can be heated or stirred at room temperature according to the solubility of the molecules;

[0032] b. Prepare a salt solution B with a certain concentration;

[0033] c. Mixing solution A and solution B in a certain proportion to form electrolyte C for electrochemical method;

[0034] d. The original copper foil D is used as the anode and the conductive material E is used as the cathode, which are immersed in the electrolyte C for electrolysis;

[0035] e. After electrolysis for a specific period of time, D is taken out, cleaned and dried to obtain a microporous copper foil F.

[0036] When copper foil is immersed in electrolyte, additive molecules can be adsorbed on the surface of copper foil. Electron-donating functional groups of additives with larger molecular weight, such as hydroxyl, amino, carboxyl, and thiol, interact with the 3d empty orbital of copper and evenly cover the surface of copper. During electrolysis, copper foil acts as an anode. Under the action of applied current / voltage, copper loses electrons to generate copper ions, and the additive covering effect on a small part of the surface of copper foil is destroyed, thereby generating holes. Microporous copper foil with different pore sizes and pore structures can be obtained by controlling the type and molecular weight of the polymer, as well as the composition of the electrolyte, the current density, and the duration of electrolysis. Polymer molecular weight and current density can affect the pore density, while the composition of the electrolyte and the duration of electrolysis can affect the pore size and depth.

[0037] In the above steps, the additive solution A is a natural or synthetic water-soluble polymer, which is one of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, carboxymethyl chitosan, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate), and polyaniline; the salt solution B is one or more of potassium sulfate, copper chloride, copper sulfate, and ferric chloride, with a concentration of 0.01 mol / L to 1 mol / L; the electrode E is one of platinum, carbon, titanium, stainless steel, copper, platinum, gold, silver, nickel, and alloys thereof; the electrolysis current in step (3) is 0.01 A / dm2 ~30A / dm 2 , the electrolysis time is 1s~20min, and the temperature is 20~70℃.

[0038]

[0039]

[0040] The electrochemical machining method of this patent has the following significant advantages:

[0041] (1) Efficient hole forming: faster than traditional physical methods and laser drilling, reducing production cycle.

[0042] (2) Precise control: The hole forming accuracy can reach several microns to tens of microns, reducing mechanical damage and improving product quality.

[0043] (3) Multi-dimensional performance improvement: It can enhance the bonding effect between microporous copper foil and electrode materials, thereby improving the charge and discharge rate performance and energy density of batteries and supercapacitors, which is beneficial to the performance optimization of batteries and supercapacitors.

[0044] (3) Wide adaptability: The hole size and density of the product can be adjusted without defects such as burrs to meet different application requirements.

[0045] Through these advantages, the electrochemical processing method developed in this patent can effectively overcome many limitations of traditional preparation methods and promote the application and development of microporous copper foil in the fields of batteries and supercapacitors.

[0046]

[0047]

[0048] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. An electrochemical method for preparing microporous copper foil, characterized in that: The specific steps are: a. preparing a water-soluble additive to form a solution A, wherein the water-soluble additive is one of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, carboxymethyl chitosan, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate), and polyaniline; b. Prepare a salt solution B of a certain concentration; the salt solution B is one or more of potassium sulfate, copper chloride, copper sulfate, and ferric chloride, and the concentration is 0.01 mol / L to 1 mol / L; c. Mixing solution A and solution B in a certain proportion to form electrolyte C for electrochemical method; d. The original copper foil D is used as the anode and the conductive material E is used as the cathode, which are immersed in the electrolyte C for electrolysis; The electrolysis current is 0.01A / dm 2 ~30A / dm 2 , the electrolysis time is 1s to 20min, the temperature is 20 to 70°C; the cathode E is one of platinum, carbon, titanium, stainless steel, copper, platinum, gold, silver, and nickel; e. After electrolysis, D is taken out, cleaned and dried to obtain microporous copper foil F.

2. The electrochemical method for preparing microporous copper foil according to claim 1, characterized in that: The micropores have an aperture size of 0-150 μm, including blind holes and through holes; blind hole copper foil refers to holes on the copper foil that do not penetrate the entire foil material, but only form holes of a certain depth on the surface; through hole copper foil refers to holes that penetrate the foil material.

3. The electrochemical method for preparing microporous copper foil according to claim 1, characterized in that: The original copper foil D is an electrolytic copper foil or a rolled copper foil.

4. The electrochemical method for preparing microporous copper foil according to claim 1, characterized in that: The conductive electrode E can be in the form of a plate or a mesh.

5. The electrochemical method for preparing microporous copper foil according to claim 1, characterized in that: In step d, the current or voltage is applied in a manner selected from the group consisting of constant current, constant voltage, periodic switching current, cyclic voltammetry, or pulse electrolysis.

6. The electrochemical method for preparing microporous copper foil according to claim 1, characterized in that: In step d, the electrolyte may be static or dynamic, and the flow mode of the dynamic electrolyte may be one of air disturbance, circulating pump, and stirring.

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