3D porous copper foil and method for manufacturing the same

Abstract

The application provides a 3D porous copper foil and a preparation method thereof. The method is used for pretreating a porous copper foil substrate to remove oil stains, oxide scales and surface particle impurities on the surface of the porous copper foil substrate, depositing on the surface of the pretreated porous copper foil substrate through a first plating solution and a second plating solution to form a micro-morphology structure layer, effectively improving the morphology consistency of the smooth surface and the rough surface of the porous copper foil, further increasing the specific surface area of the material, and optimizing the electrode interface state. Based on a third plating solution, a passivation layer is formed on the surface of the micro-morphology structure layer by electroplating, the strength defects caused by the porous structure are made up, the tensile capacity of the copper foil is improved, and the tearing and damage problems in the battery cycle process are avoided. The method strengthens the micro-morphology structure layer through the passivation layer, improves the corrosion resistance and interface bonding force of the copper foil, can reduce the corrosion of the electrolyte, ensures the stability of the electrode structure, and greatly improves the long-term cycle performance and use safety of the lithium battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery negative electrode current collector technology, specifically relating to a 3D porous copper foil and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the market's requirements for the range, cycle life, and safety performance of power batteries are constantly increasing. Traditional copper foil is no longer suitable for the needs of high-end batteries, and porous copper foil with high specific surface area has become increasingly advantageous, gradually becoming a key application material for lithium battery negative electrode current collectors.

[0003] Porous copper foil, with its three-dimensional interconnected pores and high specific surface area, can effectively alleviate lithium dendrite growth and increase the loading of active materials, making it a promising candidate for use in lithium-ion battery anode current collectors. However, existing porous copper foils still suffer from the following key defects, severely impacting battery cycle stability and safety:

[0004] First, the mechanical strength of porous copper foil decreases significantly, making it prone to tearing and breakage. While increasing the specific surface area, the porous structure reduces the effective load-bearing cross section of the copper foil and decreases its tensile strength and flexibility. During the charging and discharging process of the battery, the negative electrode active material repeatedly expands and contracts, which can easily cause cracks, tears, or even local breakage of the porous copper foil, resulting in electrode material loss, increased internal resistance, and ultimately rapid capacity decay.

[0005] Secondly, the uneven microstructure of the smooth and rough surfaces of porous copper foil leads to an imbalance in current distribution. Conventional porous copper foil has large differences in porosity and pore size distribution between the smooth and rough surfaces, resulting in uneven surface roughness. This causes localized high current density and uneven lithium deposition during the negative electrode deposition / lithiation process, making it easy for lithium dendrites to form on the surface, thereby increasing the risk of short circuits and safety hazards in the battery.

[0006] Finally, porous copper foil has insufficient corrosion resistance and is easily corroded by electrolyte during the cycling process. Porous copper foil has a large specific surface area and many defects in the pore walls, making it more susceptible to corrosion and dissolution by electrolyte under charge-discharge and over-discharge conditions. This generates copper ions that are deposited on the negative electrode surface, damaging the SEI film and exacerbating the increase in interfacial impedance and capacity decay.

[0007] Therefore, this application anticipates a method for modifying the surface of 3D porous copper foil. Summary of the Invention

[0008] To address the technical problems of low mechanical strength, uneven morphology, and insufficient corrosion resistance in existing porous copper foils, this application provides a 3D porous copper foil and its preparation method.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] In a first aspect, this application provides a method for preparing a 3D porous copper foil, comprising the following steps:

[0011] Step S1: Pre-treat the porous copper foil substrate;

[0012] Step S2: Prepare the first plating solution and the second plating solution, mix the first plating solution and the second plating solution, and deposit them on the surface of the pretreated porous copper foil substrate to form a microstructure layer. The first plating solution includes a first copper salt and a reducing agent, and the second plating solution includes a first complexing agent and a pH adjuster.

[0013] Step S3: Prepare a third plating solution, and electroplate the surface of the microstructure layer based on the third plating solution to form a passivation layer on the surface of the microstructure layer, thereby completing the preparation of 3D porous copper foil. The third plating solution includes a second copper salt, a nickel salt, and a second complexing agent.

[0014] Furthermore, during the pretreatment of the porous copper foil substrate, an acid pickling solution is used to pickle the porous copper foil substrate, followed by rinsing with deionized water and drying.

[0015] Furthermore, the first copper salt in the first plating solution is copper sulfate pentahydrate, the reducing agent is formaldehyde, the first complexing agent in the second plating solution is potassium sodium tartrate, and the pH adjusting agent is sodium hydroxide solution.

[0016] Furthermore, the Cu provided by copper sulfate pentahydrate in the first plating solution 2+ The concentration of the first plating solution is 7 g / L - 12 g / L, the formaldehyde concentration is 0.2 mol / L - 0.5 mol / L, the concentration of potassium sodium tartrate in the second plating solution is 10 g / L - 15 g / L, and the concentration of sodium hydroxide solution is 5 g / L - 10 g / L.

[0017] Furthermore, the pH value of the first and second plating solutions after mixing is 10-12, the reaction temperature during deposition is 30℃, and the deposition time is 5 min-20 min.

[0018] Furthermore, the second copper salt in the third plating solution is copper sulfate pentahydrate, the nickel salt is nickel sulfate hexahydrate, and the second complexing agent is trisodium citrate dihydrate.

[0019] Furthermore, the Cu provided by the pentahydrate sulfuric acid in the third plating solution 2+ The concentrations are 100 g / L - 150 g / L, sulfuric acid is 80 g / L - 100 g / L, nickel sulfate hexahydrate is 40 g / L - 60 g / L, and trisodium citrate dihydrate is 5-10 ppm.

[0020] Furthermore, during the electroplating process, the current density is 30 A / dm³. 2The electroplating time is 30-60 seconds.

[0021] In a second aspect, this application provides a 3D porous copper foil, which is prepared based on the preparation method of the 3D porous copper foil.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] This application provides a 3D porous copper foil and its preparation method. The method pre-treats the porous copper foil substrate to remove surface oil, oxide scale, and particulate impurities. A first and second plating solution are then deposited on the pre-treated porous copper foil substrate to form a microstructure layer, effectively improving the consistency of the morphology between the smooth and rough surfaces of the porous copper foil, further increasing the specific surface area of ​​the material, and optimizing the electrode interface state. A third plating solution is then used to electroplate the surface of the microstructure layer, forming a passivation layer on the surface of the microstructure layer. This compensates for the strength defects caused by the porous structure, improves the tensile strength of the copper foil, and avoids tearing and damage during battery cycling. This method strengthens the microstructure layer through the passivation layer, improving the corrosion resistance and interfacial adhesion of the copper foil, reducing electrolyte erosion, ensuring electrode structural stability, and significantly improving the long-term cycle performance and safety of lithium batteries. Attached Figure Description

[0024] Figure 1 A schematic diagram of the structure of the 3D porous copper foil in an embodiment of this disclosure is shown;

[0025] Figure 2 The following are scanning electron microscope images of the formation of the microstructure layer in an embodiment of this disclosure;

[0026] Figure 3 The following are scanning electron microscope images of the passivation layer during formation in an embodiment of this disclosure;

[0027] In the figure: 1-Porous copper foil substrate; 2-Microstructure layer; 3-Passivation layer. Detailed Implementation

[0028] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] Those skilled in the art can clearly understand the advantages and effects of this invention based on the disclosure in this specification. This invention can also be implemented using other different embodiments, and the relevant details in this specification can be adjusted and modified according to actual application scenarios without departing from the core spirit of this invention. It should be understood that the scope of protection of this invention is not limited to the specific embodiments described below, and the terminology used herein is only for describing embodiments and not for limiting the invention. The described embodiments are only some embodiments of this invention, not all embodiments; based on the content of this invention, all embodiments obtained by those skilled in the art without creative effort fall within the scope of protection of this invention.

[0030] This disclosure provides a method for preparing 3D porous copper foil, including the following steps:

[0031] In step S1, the porous copper foil substrate is pretreated.

[0032] Specifically, during the pretreatment of the porous copper foil substrate 1, an acid pickling solution is used to pickle the porous copper foil substrate 1. After pickling, it is rinsed with deionized water and dried. The pickling treatment uses a conventional copper-specific acid pickling solution, such as dilute sulfuric acid and hydrogen peroxide.

[0033] In step S2, a first plating solution and a second plating solution are prepared, and the first plating solution and the second plating solution are mixed and deposited on the surface of the pretreated porous copper foil substrate 1 to form a microstructure layer 2. The first plating solution includes a first copper salt and a reducing agent, and the second plating solution includes a first complexing agent and a pH adjusting agent.

[0034] Specifically, the first copper salt in the first plating solution is copper sulfate pentahydrate, the reducing agent is formaldehyde, the first complexing agent in the second plating solution is potassium sodium tartrate, and the pH adjusting agent is sodium hydroxide solution. Furthermore, the copper sulfate pentahydrate in the first plating solution provides Cu... 2+ The concentration of the first plating solution is 7 g / L - 12 g / L, the formaldehyde concentration is 0.2 mol / L - 0.5 mol / L, the concentration of potassium sodium tartrate in the second plating solution is 10 g / L - 15 g / L, and the concentration of sodium hydroxide solution is 5 g / L - 10 g / L.

[0035] In this embodiment, the pH value of the first and second plating solutions after mixing is 10-12, the reaction temperature during deposition is 30°C, and the deposition time is 5 min-20 min.

[0036] In step S3, a third plating solution is prepared, and electroplating is performed on the surface of the microstructure layer 2 based on the third plating solution to form a passivation layer 3 on the surface of the microstructure layer 2, thus completing the preparation of the 3D porous copper foil. The third plating solution includes a second copper salt, a nickel salt, and a second complexing agent.

[0037] Specifically, the second copper salt in the third plating solution is copper sulfate pentahydrate, the nickel salt is nickel sulfate hexahydrate, and the second complexing agent is trisodium citrate dihydrate. Further, the copper provided by the pentahydrate sulfuric acid in the third plating solution... 2+ The concentrations are 100 g / L - 150 g / L, sulfuric acid is 80 g / L - 100 g / L, nickel sulfate hexahydrate is 40 g / L - 60 g / L, and trisodium citrate dihydrate is 5-10 ppm.

[0038] In this embodiment, the current density during the electroplating process is 30 A / dm². 2 The electroplating time is 15-60 seconds.

[0039] This disclosure also provides a 3D porous copper foil, prepared based on the method for preparing the 3D porous copper foil, such as... Figure 1 As shown.

[0040] Example 1

[0041] The porous copper foil substrate 1 has a thickness of 4.5 μm, a porosity of 39%, a surface roughness of 1.3 μm, and a tensile strength of 210.6 MPa.

[0042] (1) The porous copper foil substrate 1 is subjected to acid pickling pretreatment. The acid pickling pretreatment is carried out by cleaning with dilute sulfuric acid, deionizing rinsing and drying, wherein the concentration of dilute sulfuric acid is 40 g / L.

[0043] (2) Prepare a first plating solution and a second plating solution. The first plating solution includes copper sulfate pentahydrate and formaldehyde, wherein the concentration of copper sulfate pentahydrate is 8 g / L and the concentration of formaldehyde is 0.2 mol / L. The second plating solution includes potassium sodium tartrate and sodium hydroxide solution, wherein the concentration of potassium sodium tartrate is 10 g / L and the concentration of sodium hydroxide solution is 8 g / L. Mix the first plating solution and the second plating solution to form a mixture with a pH of 11, a reaction temperature of 30℃, and a deposition time of 5 min, thereby forming a microstructure layer 2 on the surface of the porous copper foil substrate 1, such as... Figure 2 As shown.

[0044] (3) Prepare a third plating solution, which includes copper sulfate pentahydrate, nickel sulfate hexahydrate, and trisodium citrate dihydrate, wherein the concentration of copper sulfate pentahydrate is 100 g / L, the concentration of sulfuric acid is 90 g / L, the concentration of nickel sulfate hexahydrate is 50 g / L, and the concentration of trisodium citrate dihydrate is 5 ppm. Place the porous copper foil substrate 1 forming the microstructure layer 2 into the third plating solution for electroplating. During the electroplating, the current density is 30 A / dm³. 2 The electroplating time is 30 seconds, and a passivation layer 3 is formed on the surface of the microstructure layer 2, such as... Figure 3 As shown.

[0045] The porous copper foil processed in this embodiment has improved consistency in the smooth and rough surface morphology, moderate particle size, uniform distribution, a microstructure layer 2 thickness of 0.5 μm, a passivation layer 3 thickness of 2 μm, and a tensile strength of 245.3 MPa, which is 16% higher than the initial porous copper foil substrate 1.

[0046] Example 2

[0047] The porous copper foil substrate 1 has a thickness of 4 μm, a porosity of 31%, a surface roughness of 1.5 μm, and a tensile strength of 190.6 MPa.

[0048] (1) The porous copper foil substrate 1 is subjected to acid pickling pretreatment. The acid pickling pretreatment is carried out by cleaning with dilute sulfuric acid, deionizing rinsing and drying, wherein the concentration of dilute sulfuric acid is 40 g / L.

[0049] (2) Prepare a first plating solution and a second plating solution. The first plating solution includes copper sulfate pentahydrate and formaldehyde, wherein the concentration of copper sulfate pentahydrate is 10 g / L and the concentration of formaldehyde is 0.3 mol / L. The second plating solution includes potassium sodium tartrate and sodium hydroxide solution, wherein the concentration of potassium sodium tartrate is 15 g / L and the concentration of sodium hydroxide solution is 8 g / L. Mix the first plating solution and the second plating solution to form a mixture with a pH of 11, a reaction temperature of 30°C, and a deposition time of 5 min, thereby forming a microstructure layer 2 on the surface of the porous copper foil substrate 1.

[0050] (3) Prepare a third plating solution, which includes copper sulfate pentahydrate, nickel sulfate hexahydrate, and trisodium citrate dihydrate. The concentration of copper sulfate pentahydrate is 125 g / L, the concentration of sulfuric acid is 80 g / L, the concentration of nickel sulfate hexahydrate is 40 g / L, and the concentration of trisodium citrate dihydrate is 8 ppm. Place the porous copper foil substrate 1, which forms the microstructure layer 2, into the third plating solution for electroplating. During the electroplating, the current density is 30 A / dm³. 2 The electroplating time is 60 seconds, and a passivation layer 3 is formed on the surface of the microstructure layer 2.

[0051] The porous copper foil processed in this embodiment has improved consistency in the smooth and rough surface morphology, moderate particle size, uniform distribution, a microstructure layer 2 thickness of 1 μm, a passivation layer 3 thickness of 3 μm, and a tensile strength of 251.4 MPa, which is 31% higher than the initial porous copper foil substrate 1.

[0052] Example 3

[0053] The porous copper foil substrate 1 selected has a thickness of 4.5 μm, a porosity of 31%, a surface roughness of 1.4 μm, and a tensile strength of 195.6 MPa.

[0054] (1) The porous copper foil substrate 1 is subjected to acid pickling pretreatment. The acid pickling pretreatment is carried out by cleaning with dilute sulfuric acid, deionizing rinsing and drying, wherein the concentration of dilute sulfuric acid is 40 g / L.

[0055] (2) Prepare a first plating solution and a second plating solution. The first plating solution includes copper sulfate pentahydrate and formaldehyde, wherein the concentration of copper sulfate pentahydrate is 12 g / L and the concentration of formaldehyde is 0.5 mol / L. The second plating solution includes potassium sodium tartrate and sodium hydroxide solution, wherein the concentration of potassium sodium tartrate is 12 g / L and the concentration of sodium hydroxide solution is 10 g / L. Mix the first plating solution and the second plating solution to form a mixture with a pH of 12, a reaction temperature of 30°C, and a deposition time of 5 min, thereby forming a microstructure layer 2 on the surface of the porous copper foil substrate 1.

[0056] (3) Prepare a third plating solution, which includes copper sulfate pentahydrate, nickel sulfate hexahydrate, and trisodium citrate dihydrate. The concentration of copper sulfate pentahydrate is 150 g / L, the concentration of sulfuric acid is 100 g / L, the concentration of nickel sulfate hexahydrate is 60 g / L, and the concentration of trisodium citrate dihydrate is 10 ppm. Place the porous copper foil substrate 1, which forms the microstructure layer 2, into the third plating solution for electroplating. During the electroplating, the current density is 30 A / dm³. 2 The electroplating time is 30 seconds, and a passivation layer 3 is formed on the surface of the microstructure layer 2.

[0057] The porous copper foil processed in this embodiment has improved consistency in the smooth and rough surface morphology, moderate particle size, uniform distribution, a microstructure layer 2 thickness of 1 μm, a passivation layer 3 thickness of 2 μm, and a tensile strength of 241.6 MPa, which is 23% higher than the initial porous copper foil substrate 1.

Claims

1. A method for preparing a 3D porous copper foil, characterized in that, Includes the following steps: Step S1: Pre-treat the porous copper foil substrate; Step S2: Prepare the first plating solution and the second plating solution, mix the first plating solution and the second plating solution, and deposit them on the surface of the pretreated porous copper foil substrate to form a microstructure layer. The first plating solution includes a first copper salt and a reducing agent, and the second plating solution includes a first complexing agent and a pH adjuster. Step S3: Prepare a third plating solution, and electroplate the surface of the microstructure layer based on the third plating solution to form a passivation layer on the surface of the microstructure layer, thereby completing the preparation of 3D porous copper foil. The third plating solution includes a second copper salt, a nickel salt, and a second complexing agent.

2. The method for preparing 3D porous copper foil according to claim 1, characterized in that, When pretreating the porous copper foil substrate, the porous copper foil substrate is pickled with an acid pickling solution, rinsed with deionized water after pickling, and then dried.

3. The method for preparing 3D porous copper foil according to claim 1, characterized in that, The first copper salt in the first plating solution is copper sulfate pentahydrate, the reducing agent is formaldehyde, the first complexing agent in the second plating solution is potassium sodium tartrate, and the pH adjuster is sodium hydroxide solution.

4. The method for preparing 3D porous copper foil according to claim 3, characterized in that, The Cu provided by copper sulfate pentahydrate in the first plating solution 2+ The concentration of the first plating solution is 7 g / L - 12 g / L, the formaldehyde concentration is 0.2 mol / L - 0.5 mol / L, the concentration of potassium sodium tartrate in the second plating solution is 10 g / L - 15 g / L, and the concentration of sodium hydroxide solution is 5 g / L - 10 g / L.

5. The method for preparing 3D porous copper foil according to claim 1, characterized in that, The pH value of the first and second plating solutions after mixing is 10-12, the reaction temperature during deposition is 30℃, and the deposition time is 5 min-20 min.

6. The method for preparing 3D porous copper foil according to claim 1, characterized in that, The second copper salt in the third plating solution is copper sulfate pentahydrate, the nickel salt is nickel sulfate hexahydrate, and the second complexing agent is trisodium citrate dihydrate.

7. The method for preparing 3D porous copper foil according to claim 6, characterized in that, The Cu provided by the pentahydrate sulfuric acid in the third plating solution 2+ The concentrations are 100 g / L - 150 g / L, sulfuric acid is 80 g / L - 100 g / L, nickel sulfate hexahydrate is 40 g / L - 60 g / L, and trisodium citrate dihydrate is 5-10 ppm.

8. The method for preparing 3D porous copper foil according to claim 1, characterized in that, During the electroplating process, the current density is 30 A / dm². 2 The electroplating time is 30-60 seconds.

9. A 3D porous copper foil, characterized in that, The 3D porous copper foil was prepared according to the preparation method of any one of claims 1-8.

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