Preparation method of porous copper foil based on hydrogel template and porous copper foil

Abstract

The application discloses a preparation method of porous copper foil based on a hydrogel template and the porous copper foil. The method comprises the following steps: firstly, a hydrogel solution is applied to the surface of a cathode roller by spraying, and a hydrogel shielding point array is formed by using the self-polymerization characteristics of the hydrogel solution; secondly, electrolysis is performed on the area of the cathode roller outside the shielding point as a deposition site, so that a composite copper foil with the hydrogel shielding point is prepared; then, the composite copper foil is peeled off from the cathode roller, and is ultrasonically treated in an alkaline solution for 0.5-5 min, so that the hydrogel shielding point is swelled and then falls off through ultrasonic vibration, and a pure porous copper foil is obtained; finally, the porous copper foil is subjected to surface treatment by using a passivation liquid, and the stability of the porous copper foil is improved. The method realizes accurate regulation and control of the porous structure through the hydrogel template, is green and efficient in the preparation process, and the obtained porous copper foil has the advantages of uniform pore distribution, large specific surface area and good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic copper foil technology, specifically relating to a method for preparing porous copper foil based on hydrogel template and the porous copper foil itself. Background Technology

[0002] With the rapid development of electric vehicles and portable electronic devices, the market has placed higher demands on the energy density and safety of batteries. Solid-state batteries, due to their outstanding advantages such as high energy density and high safety, have become a research hotspot in the current new energy field. As a key component of the battery, the current collector's performance directly affects the overall electrochemical performance and safety stability of the battery. In the anode structure of a solid-state battery, the current collector needs to provide a stable support for the active material and achieve efficient electron conduction.

[0003] When traditional planar copper foil is used as a negative electrode current collector, it has the problem of small specific surface area, which results in limited space for lithium metal deposition and easily leads to lithium dendrite growth. At the same time, during the battery charge and discharge cycle, the volume change of the electrode material is difficult to be effectively mitigated, which in turn leads to a shortened battery cycle life and increased safety risks.

[0004] In existing technologies, mechanical stamping or laser etching easily produces defects such as burrs and microcracks, leading to a decline in the mechanical properties of copper foil and poor pore size uniformity. Etching copper foil with acidic or alkaline etching solutions easily causes embrittlement, significantly reducing mechanical strength and causing substantial environmental pollution. The method of adding shielding points to the surface of the cathode roller suffers from problems such as the shielding points easily detaching and adhering to the copper foil. Although existing technologies have made some progress, the key contradiction in the preparation of porous copper foil remains unresolved: how to achieve large-scale production with uniform pore size and controllable porosity without damaging the mechanical properties of the copper foil. Summary of the Invention

[0005] To address the aforementioned technical problems, particularly the difficulty of shielding points easily detaching and leaving residues, this invention proposes a method for preparing porous copper foil based on a hydrogel template and a porous copper foil in general. By developing a shielding point technology that is easy to remove and leaves no residue, the shielding points are prevented from adhering to the copper foil surface when the template is peeled off. A porous copper foil with uniform pore size and high mechanical strength is prepared to meet the requirements of high-performance solid-state batteries.

[0006] In a first aspect, the present invention proposes a method for preparing porous copper foil based on a hydrogel template, comprising: Step 1: Preparation of shielding dot array; The hydrogel solution is applied to the surface of the cathode roller by spraying, and the self-polymerization property of the hydrogel solution is used to form a hydrogel shielding dot array on the surface of the cathode roller. Step 2: Electrodeposition to prepare composite copper foil; Electrolysis is performed using the cathode roller area outside the hydrogel shielding point as the deposition site to obtain a composite copper foil with hydrogel shielding point interspersed. Step 3, Degeling; After electrodeposition, the composite copper foil is peeled off from the surface of the cathode roller and placed in an alkaline solution for ultrasonic treatment for 0.5-5 minutes. The hydrogel shielding points swell and then fall off by ultrasonic vibration to obtain a pure porous copper foil. Step 4: Use a passivation solution to perform surface treatment on the porous copper foil to obtain porous copper foil.

[0007] The hydrogel solution contains: 20-30 wt% monomer, wherein the monomer is acrylic acid and its derivatives; 0.2-1 wt% sodium hydroxide; 0.2-1 wt% initiator; 1-10 wt% insulating particles; and the balance being ultrapure water.

[0008] The insulating particles are prepared using insulating polymer materials.

[0009] The surface roughness of the cathode roller is Rz≤1μm, Ra≤0.2μm, and the surface temperature of the cathode roller is 45-50℃.

[0010] The height of the hydrogel shielding point is 4.0-8μm, the diameter of the hole is 8-16μm, and the spacing between adjacent holes in the hydrogel shielding point array is 4-16μm.

[0011] The electrolyte comprises: Cu2+ concentration of 70-80 g / L, sulfuric acid concentration of 108-128 g / L, chloride ion concentration of 5-15 mg / L, hydrolyzed collagen concentration of 10-15 mg / L, SPS concentration of 20-30 mg / L, and polyvinyl alcohol concentration of 10-15 mg / L.

[0012] The electrolysis temperature is 52-54℃, and the current is 20-35kA; The hydrolyzed collagen has a molecular weight of 5000-10000 Da; The molecular weight of the polyvinyl alcohol is 10,000-20,000 Da.

[0013] The alkaline solution is composed of an ultrapure aqueous solution of sodium hydroxide, with a pH ≥ 10 and a temperature of 20-30℃; the frequency of the ultrasonic waves used in the ultrasonic treatment can be set to 20-50 kHz, and the amplitude of the ultrasonic waves can be less than 10 μm.

[0014] The surface treatment of porous copper foil was carried out using a passivation solution containing 80-100 mg / L chromic anhydride, 160-200 mg / L glucose, and ultrapure water. The pH of the passivation solution was 3-4, the passivation temperature was 30-35℃, and the passivation current was 2 A / dm³. 2 .

[0015] Secondly, the present invention also provides a porous copper foil, which is prepared by the method for preparing porous copper foil based on hydrogel template as described above; the porous copper foil has a pore size of 10-300 μm and a porosity of 5%-30%.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes sodium polyacrylate hydrogel to prepare shielding points on the surface of a cathode roller. By leveraging its excellent mechanical strength during electrodeposition and its easy removal characteristics under alkaline conditions, it effectively solves the technical pain points of traditional shielding points, such as easy detachment and adhesion to copper foil. The porous copper foil obtained by this invention has the outstanding advantages of uniform pore size, controllable porosity, and high mechanical strength. When used as a current collector in solid-state batteries, it can efficiently suppress lithium dendrite growth, significantly alleviate volume changes in electrode materials during charging and discharging, and thus greatly improve the cycle life and safety performance of the battery. Attached Figure Description

[0017] Figure 1 This is a process diagram illustrating a method for preparing porous copper foil based on a hydrogel template, as shown in an embodiment of the present invention.

[0018] Figure 2 This is a diagram illustrating the processing effect of porous copper foil according to an embodiment of the present invention.

[0019] Figure 3 This is a diagram of a porous copper foil with a porosity of 30% as shown in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1: As Figure 1-2 As shown, this invention proposes a method for preparing porous copper foil based on a hydrogel template, specifically including: Step 1: Preparation of the shielding point array.

[0022] Preferably, a hydrogel shielding dot array is formed by self-polymerization of a hydrogel solution sprayed on the surface of the cathode roller; the hydrogel solution contains: 20-30 wt% monomer, 0.2-1 wt% sodium hydroxide, 0.2-1 wt% initiator, 1-10 wt% insulating particles, and the balance being ultrapure water.

[0023] Preferably, the monomer is acrylic acid and its derivatives, with acrylic acid being the most preferred.

[0024] The initiator is a thermal initiator or a visible light initiator, preferably ammonium persulfate.

[0025] The insulating particles are particles made of insulating polymer materials, preferably PVC or PI particles.

[0026] The surface roughness of the cathode roller is Rz≤1μm, Ra≤0.2μm, and the surface temperature of the cathode roller is controlled at 45-50℃; the height of the hydrogel shielding point is 4.0-8μm, the diameter of the hole is 8-16μm, and the spacing between adjacent holes in the hydrogel shielding point array is 4-16μm.

[0027] Step 2: Electrodeposition to prepare composite copper foil.

[0028] Preferably, electrolysis is performed in the electrolyte using a cathode roller outside the hydrogel shielding point to obtain a composite copper foil with intercalated hydrogel shielding points.

[0029] Preferably, the electrolyte comprises: Cu²⁺, sulfuric acid, chloride ions, hydrolyzed collagen, SPS, polyvinyl alcohol, and ultrapure water; wherein the concentration of Cu²⁺ is 70-80 g / L, the concentration of sulfuric acid is 108-128 g / L, the concentration of chloride ions is 5-15 mg / L, the concentration of hydrolyzed collagen is 10-15 mg / L, the concentration of SPS is 20-30 mg / L, and the concentration of polyvinyl alcohol is 10-15 mg / L; the molecular weight of the hydrolyzed collagen is 5000-10000 Da; the molecular weight of the polyvinyl alcohol is 10000-20000 Da; the electrolysis temperature is 52-54℃, and the current is 20-35 kA. It should be noted that in this step, the strong acid electrolyte environment will cause the sodium polyacrylate network to gradually transform into a polyacrylate network, forming rich dynamic hydrogen bond interactions, giving the hydrogel shielding points excellent anti-swelling and self-healing properties, significantly improving its mechanical strength, and ensuring that the structural integrity is maintained during the electrodeposition process.

[0030] Step 3: Degelatinize.

[0031] After electrodeposition, the composite copper foil is peeled off from the surface of the cathode roller and placed in an alkaline solution for ultrasonic treatment for 0.5-5 minutes. The hydrogel shielding points swell and then fall off after ultrasonic vibration, resulting in a pure porous copper foil.

[0032] Preferably, the alkaline solution is an ultrapure aqueous solution of sodium hydroxide with a pH ≥ 10 and a temperature controlled at 20-30℃; the ultrasonic frequency of the ultrasonic treatment is 20-50kHz and the ultrasonic amplitude is less than 10μm.

[0033] Step 4: Surface treatment of porous copper foil The surface treatment of porous copper foil is carried out using a passivation solution containing 80-100 mg / L of chromic anhydride, 160-200 mg / L of glucose, and ultrapure water. The pH of the passivation solution is 3-4, the passivation temperature is 30-35℃, and the passivation current is 2 A / dm².

[0034] To further illustrate the technical effects of the solution described in this invention, a further embodiment is as follows: Experiment 1: Step 1: Preparation of the shielding dot array: Prepare a hydrogel solution with the following composition: 25wt% acrylic acid, 0.5wt% sodium hydroxide, 0.5wt% ammonium persulfate, 5wt% PVC particles, and the balance being ultrapure water; grind the surface of the cathode roller to a roughness of Rz = 0.8μm and Ra = 0.15μm, and control the surface temperature of the cathode roller to 48℃ using a heating device; use a precision spraying device to uniformly spray the hydrogel solution onto the surface of the cathode roller, and after the solution has self-polymerized, a hydrogel shielding dot array with a height of 6μm, a hole diameter of 12μm, and a spacing of 10μm between adjacent holes is formed.

[0035] Step 2: Electrodeposition to prepare composite copper foil: Prepare the electrolyte by sequentially adding copper sulfate, sulfuric acid, sodium chloride, hydrolyzed collagen (molecular weight 8000 Da), SPS, and polyvinyl alcohol (molecular weight 15000 Da) to ultrapure water and stirring until completely dissolved. The concentrations of each component are as follows: Cu²⁺ concentration 75 g / L, sulfuric acid concentration 118 g / L, chloride ion concentration 10 mg / L, hydrolyzed collagen concentration 12 mg / L, SPS concentration 25 mg / L, and polyvinyl alcohol concentration 12 mg / L. Use a cathode roller with a hydrogel shielding point array as the cathode and a pure copper block as the anode in the above electrolyte. Control the electrolysis temperature at 53℃ and the electrolysis current at 28 kA. After electrolysis for 30 min, a composite copper foil with hydrogel shielding points is obtained on the surface of the cathode roller.

[0036] Step 3, Degelation: After electrodeposition, the composite copper foil is peeled off from the surface of the cathode roller and placed in an ultrasonic bath containing an ultrapure sodium hydroxide solution at pH=11 and temperature of 25℃. The ultrasonic frequency is set to 35kHz and the amplitude to 8μm, and the ultrasonic treatment is carried out for 2 minutes. During this period, the hydrogel shielding points are fully swollen in the alkaline solution and completely detached by ultrasonic vibration. The copper foil is then taken out and rinsed 3 times with ultrapure water to obtain a pure porous copper foil.

[0037] Step 4: Surface treatment of porous copper foil: Prepare a passivation solution by adding chromium anhydride and glucose to ultrapure water and stirring until dissolved. Adjust the pH of the passivation solution to 3.5 with dilute sulfuric acid, where the concentration of chromium anhydride is 90 mg / L and the concentration of glucose is 180 mg / L. Place the porous copper foil as the cathode and graphite as the anode in the passivation solution, control the passivation temperature at 32℃ and the passivation current at 2A / dm², and remove it after 10 minutes. Allow it to air dry naturally to obtain the final porous copper foil product.

[0038] Testing revealed that the porous copper foil prepared in this embodiment had a pore size uniformity of 92%, a porosity of 45%, and a tensile strength of 280 MPa. When used as a negative electrode current collector in a solid-state battery assembly, the battery capacity retention rate was 89% after 1000 charge-discharge cycles.

[0039] Experiment 2: Step 1: Preparation of the shielding dot array: Prepare a hydrogel solution with the following composition: 20wt% acrylic acid, 0.2wt% sodium hydroxide, 0.2wt% ammonium persulfate, 1wt% PI particles, and the balance being ultrapure water; grind the surface of the cathode roller to Rz = 0.5μm and Ra = 0.1μm, and control the surface temperature at 45℃; after spraying the hydrogel solution, self-polymerize to form a hydrogel shielding dot array with a height of 4μm, a hole diameter of 8μm, and a spacing of 4μm between adjacent holes.

[0040] Step 2: Electrodeposition to prepare composite copper foil: The electrolyte composition is Cu²⁺ concentration 70 g / L, sulfuric acid concentration 108 g / L, chloride ion concentration 5 mg / L, hydrolyzed collagen (molecular weight 5000 Da) concentration 10 mg / L, SPS concentration 20 mg / L, and polyvinyl alcohol (molecular weight 10000 Da) concentration 10 mg / L; the electrolysis temperature is 52℃, the current is 20 kA, and the electrolysis time is 25 min to obtain composite copper foil.

[0041] Step 3, Degelation: The composite copper foil is placed in a sodium hydroxide aqueous solution with pH=10 and temperature of 20℃, and ultrasonically treated for 0.5 min with an ultrasonic frequency of 20kHz and an amplitude of 5μm. After rinsing, a porous copper foil is obtained.

[0042] Step 4: Surface treatment of porous copper foil: The passivation solution contains chromic anhydride concentration of 80 mg / L, glucose concentration of 160 mg / L, pH=3, treatment temperature of 30℃, current of 2A / dm², and treatment time of 8 min.

[0043] Test results: pore size uniformity 90%, porosity 40%, tensile strength 260MPa; capacity retention rate 85% after 1000 battery cycles.

[0044] Experiment 3: Step 1: Preparation of shielding dot array: The hydrogel solution consists of 30wt% acrylic acid, 1wt% sodium hydroxide, 1wt% ammonium persulfate, 10wt% PVC particles, and the balance is ultrapure water; the surface of the cathode roller is polished to Rz = 1μm, Ra = 0.2μm, and the surface temperature is 50℃; self-polymerization forms a shielding dot array with a height of 8μm, a hole diameter of 16μm, and a spacing of 16μm between adjacent holes.

[0045] Step 2: Electrodeposition to prepare composite copper foil: The electrolyte contains Cu²⁺ concentration of 80 g / L, sulfuric acid concentration of 128 g / L, chloride ion concentration of 15 mg / L, hydrolyzed collagen with a molecular weight of 10000 Da concentration of 15 mg / L, SPS concentration of 30 mg / L, and polyvinyl alcohol with a molecular weight of 20000 Da concentration of 15 mg / L; the electrolysis temperature is 54℃, the current is 35 kA, and the electrolysis time is 35 min.

[0046] Step 3, Degelation: Alkaline solution pH=12, temperature 30℃, ultrasonic frequency 50kHz, amplitude 9μm, ultrasonic treatment for 5min.

[0047] Step 4: Surface treatment of porous copper foil: passivation solution with chromic anhydride concentration of 100 mg / L, glucose concentration of 200 mg / L, pH = 4, treatment temperature of 35℃, current of 2 A / dm², treatment time of 12 min.

[0048] Test results: pore size uniformity 93%, porosity 50%, tensile strength 290MPa; capacity retention rate 90% after 1000 battery cycles.

[0049] It should be noted that the above three embodiments are based on the hydrogel template preparation method of the present invention. By adjusting the composition of the hydrogel solution and process parameters, differentiated performance design of porous copper foil is achieved. Its core functions and advantages are as follows: Experiment 1 (Intermediate Parameter Group): Using intermediate parameters such as 25wt% acrylic acid and 5wt% PVC particles, the prepared porous copper foil has balanced comprehensive performance, with a pore size uniformity of 92%, a suitable moderate porosity of 20%, a moderate tensile strength of 310MPa, and a moderate elongation of 3.3%. It not only ensures sufficient space for lithium metal deposition but also has good structural stability, making it suitable for mainstream solid-state battery scenarios with comprehensive performance requirements. The battery retains 89% of its capacity after 1000 cycles, demonstrating excellent cycle stability.

[0050] Experiment 2 (Low Parameter Group): Using 20wt% acrylic acid, 1wt% PI particles, and lower electrolysis current, ultrasonic time, and other parameters, the porous copper foil has a smaller pore size (8μm), is suitable for lower porosity (5%), has higher tensile strength (360MPa), and higher elongation (4.5%), but the preparation cost is relatively low and the process time is shorter. It is suitable for mid-to-low-end solid-state batteries or experimental scenarios where porosity requirements are not high and economy is the focus. The battery capacity retention rate of 85% still meets the basic cycle requirements.

[0051] Experiment 3 (High-parameter group): Using 30wt% acrylic acid, 10wt% PVC granules, and higher electrolysis temperature and current parameters, the porosity of porous copper foil can be increased to 30%. Figure 3 The diagram shows a porous copper foil with a porosity of 30% as illustrated in this embodiment of the invention. Suitable for applications requiring higher porosity, it still exhibits good tensile strength of 280 MPa, elongation of 2.6%, and pore size uniformity of 93%. While meeting mechanical performance requirements, its larger specific surface area further suppresses lithium dendrite growth and better buffers electrode volume changes, making it suitable for high-end solid-state battery applications with high energy density and long cycle life. The battery retains 90% of its capacity after 1000 cycles, demonstrating optimal electrochemical performance.

[0052] In comparison, it can be seen that: 1. Porosity is positively correlated with the amount of sprayed gel.

[0053] 2. When the gel monomer content is within 20-30 wt%, the gel column is firm and dense, and the edges of the deposited copper holes are relatively clear; when the gel monomer content is <20-30 wt%, the gel column is easy to fall off, and the hole edges are blurred, and it is easy to tear the edges during peeling; when the gel monomer content is greater than 20-30 wt%, the gel column is too firm and difficult to peel off or remove from the copper foil pores.

[0054] 3. Organic polymer particles provide insulation and enhance the gelation effect. Too few particles will result in weak insulation of the gel column, leading to blurred edges of the copper foil holes. Too many particles will easily result in weak adhesion strength and detachment from the cathode roller. The concentration range of copper acid in electrolytic deposition has no effect on porosity, and tensile strength and elongation can be consistent; the more pores, the lower the tensile strength and elongation.

[0055] In summary, the present invention, through the above three embodiments, relies on the unique properties of the sodium polyacrylate hydrogel shielding point to enhance mechanical strength through dynamic hydrogen bonding during the electrodeposition process, thus preventing the shielding point from falling off; during the degelation stage, it easily swells and falls off in alkaline solution without residual pollution; the final products all have the characteristics of uniform pore size and controllable structure, and can effectively improve the lithium deposition behavior and cycle stability of solid-state batteries when used as negative electrode current collectors.

[0056] As can be seen, this invention uses sodium polyacrylate hydrogel as the shielding point material, utilizing its dynamic hydrogen bond recombination strengthening mechanism in an acidic environment and its swelling and weakening mechanism in an alkaline solution to achieve high mechanical strength of the shielding point during electrodeposition and easy removal in an alkaline environment later. This effectively solves the technical problems of easy detachment and difficult removal of traditional epoxy resin shielding points.

[0057] Example 2: The present invention also provides a porous copper foil, which is prepared by the method for preparing porous copper foil based on hydrogel template as described above; the porous copper foil has a pore size of 10-300 μm and a porosity of 5%-30%.

[0058] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of the invention. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as claimed in the appended claims.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the statement "comprising a…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] Although the description of the invention has been given in conjunction with the specific embodiments described above, it will be apparent to those skilled in the art that many substitutions, modifications, and variations can be made based on the foregoing. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A method for preparing porous copper foil based on a hydrogel template, characterized in that, include: Step 1: Preparation of the shielding point array; The hydrogel solution is applied to the surface of the cathode roller by spraying, and the self-polymerization property of the hydrogel solution is used to form a hydrogel shielding dot array on the surface of the cathode roller. Step 2: Electrodeposition to prepare composite copper foil; Electrolysis was performed using the cathode roller area outside the hydrogel shielding point as the deposition site to obtain a composite copper foil with the hydrogel shielding point interspersed. Step 3: Degelatinization; After electrodeposition, the composite copper foil is peeled off from the surface of the cathode roller and placed in an alkaline solution for ultrasonic treatment for 0.5-5 minutes. The hydrogel shielding points swell and then fall off after ultrasonic vibration, resulting in a pure porous copper foil. Step 4: Perform surface treatment on the porous copper foil using a passivation solution to obtain the porous copper foil; The hydrogel solution contains: 20-30 wt% of a monomer, wherein the monomer is acrylic acid; 0.2-1 wt% of sodium hydroxide; 0.2-1 wt% of an initiator; 1-10 wt% of insulating particles; and the balance being ultrapure water.

2. The method for preparing porous copper foil based on a hydrogel template according to claim 1, characterized in that, The insulating particles are prepared using insulating polymer materials.

3. The method for preparing porous copper foil based on a hydrogel template according to claim 2, characterized in that, The surface roughness of the cathode roller is Rz≤1μm, Ra≤0.2μm, and the surface temperature of the cathode roller is 45-50℃.

4. The method for preparing porous copper foil based on a hydrogel template according to claim 3, characterized in that, The height of the hydrogel shielding point is 4.0-8μm, the diameter of the hole is 8-16μm, and the spacing between adjacent holes in the hydrogel shielding point array is 4-16μm.

5. The method for preparing porous copper foil based on a hydrogel template according to claim 4, characterized in that, In step 2, the electrolyte used for electrodeposition includes: Cu2+ concentration of 70-80 g / L, sulfuric acid concentration of 108-128 g / L, chloride ion concentration of 5-15 mg / L, hydrolyzed collagen concentration of 10-15 mg / L, SPS concentration of 20-30 mg / L, and polyvinyl alcohol concentration of 10-15 mg / L.

6. The method for preparing porous copper foil based on a hydrogel template according to claim 5, characterized in that, The electrolysis temperature is 52-54℃, and the current is 20-35kA; The hydrolyzed collagen has a molecular weight of 5000-10000 Da; The molecular weight of the polyvinyl alcohol is 10,000-20,000 Da.

7. The method for preparing porous copper foil based on a hydrogel template according to claim 6, characterized in that, The alkaline solution is composed of an ultrapure aqueous solution of sodium hydroxide, with a pH ≥ 10 and a temperature of 20-30℃; the frequency of the ultrasonic waves used in the ultrasonic treatment is set to 20-50 kHz, and the amplitude of the ultrasonic waves is less than 10 μm.

8. The method for preparing porous copper foil based on a hydrogel template according to claim 7, characterized in that, The surface treatment of porous copper foil was carried out using a passivation solution containing 80-100 mg / L chromic anhydride, 160-200 mg / L glucose, and ultrapure water. The pH of the passivation solution was 3-4, the passivation temperature was 30-35℃, and the passivation current was 2 A / dm³. 2 .

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