A long-life titanium anode for electrolytic copper foil production and a method for preparing the same

Abstract

This invention relates to a long-life titanium anode for electrolytic copper foil production and its preparation method, belonging to the field of electrolytic copper foil technology. The long-life titanium anode comprises: a titanium substrate; a laser nitriding layer formed on the surface of the titanium substrate; and a composite coating formed on the surface of the laser nitriding layer, the composite coating comprising, from the inside out, a bottom layer, an intermediate layer, and a top layer; the bottom layer is an IrO2-Ta2O5 composite oxide coating, and the intermediate layer is an IrO2-Ta2O5-PdO2 composite oxide coating. x The composite oxide coating, wherein the intermediate layer is IrO2-Ta2O5-PdO x With PdO x Nanoparticles as the core, IrO2 and Ta2O5 in PdO x A coating layer is formed on the surface, which is a PbO2 coating doped with rare earth elements. This invention solves the problems of substrate passivation and peeling through laser nitriding, achieves a balance between high conductivity and high corrosion resistance by utilizing a core-shell structure intermediate layer, and improves catalytic activity and stability by combining the rare earth-doped surface layer. The synergistic effect of each layer significantly extends the service life of the anode.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic copper foil technology, and relates to a long-life titanium anode for electrolytic copper foil production and its preparation method. Background Technology

[0002] Electrolytic copper foil is a key raw material for printed circuit boards and lithium-ion batteries. Its production process typically uses titanium-based coated anodes as insoluble anodes. Traditional titanium anodes usually have an iridium- or ruthenium-based oxide coating on the titanium substrate surface. However, titanium anodes have the following problems in practical applications: First, during long-term electrolysis, oxygen atoms can easily diffuse to the titanium substrate surface through microcracks or pores in the coating, forming a non-conductive TiO2 passivation film, leading to a sharp increase in resistance and anode failure. Second, the significant difference in thermal expansion coefficients between the titanium substrate and the oxide coating easily generates thermal stress during start-up, shutdown, or temperature fluctuations, causing the coating to peel off. Third, existing single-layer or double-layer coating systems cannot simultaneously meet the requirements of high oxygen evolution catalytic activity, high conductivity, and high corrosion resistance. Furthermore, traditional PbO2 coatings suffer from coarse grains, high internal stress, and susceptibility to cracking, and are prone to grain coarsening during long-term operation, leading to decreased activity.

[0003] Therefore, there is an urgent need to develop a long-life titanium anode for the production of electrolytic copper foil and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a long-life titanium anode for the production of electrolytic copper foil and its preparation method, which has the characteristic of a longer service life.

[0005] The objective of this invention can be achieved through the following technical solutions: A long-life titanium anode for the production of electrolytic copper foil, the long-life titanium anode comprising: Titanium substrate; A laser nitriding layer formed on the surface of the titanium substrate; A composite coating is formed on the surface of the laser nitrided layer, the composite coating comprising, from the inside out, a base layer, an intermediate layer and a surface layer; The bottom layer is an IrO2-Ta2O5 composite oxide coating. The intermediate layer is IrO2-Ta2O5-PdO x Composite oxide coating, The surface layer is a PbO2 coating doped with rare earth elements.

[0006] As a preferred embodiment of the present invention, the thickness of the laser nitrided layer is 5~8μm.

[0007] As a preferred embodiment of the present invention, the intermediate layer IrO2-Ta2O5-PdOx PdO x The core is composed of nanoparticles, with an oxidation stoichiometry x ranging from 1.2 to 1.8. IrO2 and Ta2O5 are present in PdO. x A coating layer is formed on the surface.

[0008] As a preferred embodiment of the present invention, the rare earth element doped in the surface layer is Ce.

[0009] A method for preparing a long-life titanium anode for electrolytic copper foil production, the method comprising the following steps: S5-1. Titanium substrate pretreatment: The titanium substrate is subjected to sandblasting and acid etching treatment in sequence to obtain a pretreated titanium substrate. S5-2, Laser nitriding treatment: The pretreated titanium substrate is scanned in a nitrogen atmosphere using a laser beam to obtain a laser nitriding layer; S5-3. Preparation of the bottom layer: Coat the surface of the laser nitrided layer with a precursor solution containing Ir and Ta, dry it at 80~100℃, and then place it in a muffle furnace to heat to 500~520℃ and keep it at that temperature for 1~2 h to obtain the bottom layer. S5-4. Preparation of intermediate layer: Coating with a precursor solution containing Pd, drying at 80~100℃, then placing in a muffle furnace and heating to 450~480℃ and holding for 1~2 h, then coating with a precursor solution containing Ir and Ta, drying at 80~100℃, then placing in a muffle furnace and heating to 470~490℃ and holding for 1~2 h to obtain the intermediate layer; S5-5, Surface preparation: Heat the electroplating solution to 50~70℃, place the titanium substrate after step S5-4 as the anode plate into the electroplating solution, use a pure titanium plate as the cathode material, and the distance between the anode and the cathode is 10±0.5cm. Deposit the surface layer by electrodeposition to obtain the long-life titanium anode.

[0010] As a preferred technical solution of the present invention, in step S5-1, the surface roughness Ra is 5~10μm after sandblasting; the acid etching step is to immerse the titanium substrate in an 8~10wt% oxalic acid solution and sonicate it at 60~80℃ for 1~2 h.

[0011] As a preferred embodiment of the present invention, the laser power in the laser nitriding process is 500~1000W, the scanning speed is 100~500mm / min, the spot diameter is 3~5mm, the nitrogen flow rate is 20~50L / min, and the nitrogen purity is ≥99.9%.

[0012] As a preferred embodiment of the present invention, the molar ratio of Ir to Ta in the bottom layer is (3~5):(2~3).

[0013] As a preferred embodiment of the present invention, the molar ratio of Ir, Ta and Pd in ​​the intermediate layer is (4~6):(1~3):(2~4).

[0014] As a preferred embodiment of the present invention, the electrodeposition bath comprises: 100-200 g / L lead acetate, 30-40 g / L nitric acid, 20-30 g / L polyethylene glycol, 2-3 g / L polyvinylpyrrolidone, and 3-5 g / L soluble salts of rare earth elements; the electrodeposition current density is 150-200 A / m. 2 The deposition time is 30-40 min.

[0015] The laser-nitrided layer is formed by in-situ laser scanning of the titanium substrate surface in a nitrogen-containing atmosphere. This layer is a hybrid structure of titanium and titanium nitride doped with titanium nitride, exhibiting unique gradient transition characteristics. First, the titanium nitride phase possesses extremely high chemical stability and oxygen atom diffusion blocking ability, forming a dense chemical barrier between the coating and the titanium substrate. This effectively prevents oxygen atoms or reactive oxygen species in the electrolyte from penetrating into the titanium substrate, avoiding the sharp increase in resistance and failure problems caused by the formation of a TiO2 passivation film on the substrate surface in traditional titanium anodes. Second, this laser-nitrided layer is not a pure ceramic layer, but a gradient hybrid structure composed of metallic titanium and titanium nitride. Its coefficient of thermal expansion is between that of the titanium substrate and the upper oxide coating, achieving a gradual transition in the coefficient of thermal expansion. This buffers thermal stress caused by temperature fluctuations or start-up / shutdown conditions, eliminating the risk of interface peeling caused by excessive differences in the coefficient of thermal expansion in traditional coatings. Furthermore, the laser-nitrided layer and the titanium substrate are bonded in situ using metallurgical bonding, providing a stable and robust underlying foundation for subsequent multilayer oxide coatings.

[0016] The bottom layer adopts an IrO2-Ta2O5 composite oxide system. IrO2 is a highly efficient electrocatalyst for the oxygen evolution reaction, which can significantly reduce the oxygen evolution overpotential at the anode and reduce electrolysis energy consumption. Ta2O5, as a stabilizer, can effectively inhibit the dissolution and grain coarsening of IrO2 during long-term electrolysis after forming a solid solution with IrO2, thus greatly extending the service life of the coating. The structure formed by the oxide during thermal decomposition increases the specific surface area of ​​the coating and maintains good mechanical adhesion, providing an ideal substrate for the deposition of the intermediate layer.

[0017] The intermediate layer is PdO x Nanoparticles serve as the core, with IrO2 and Ta2O5 forming a coating layer on their surface. This design solves the problem of achieving both high conductivity and high corrosion resistance in traditional anode interlayers. Firstly, PdO... xThe core is a mixed-valence oxide, whose electronic conductivity is superior to that of stoichiometric PdO or conventional IrO2 coatings. This allows it to form an electron transport pathway throughout the coating system, significantly reducing interlayer contact resistance and ohmic polarization, ensuring stable anode operation under high current densities. Furthermore, the IrO2-Ta2O5 shell not only provides auxiliary oxygen evolution catalytic activity but also enhances the performance of PdO... x The core forms a dense physical shield, preventing PdO from being released in an acidic oxygen evolution environment. x Oxidation and dissolution occur. Furthermore, the stepwise thermal decomposition process ensures a clear and controllable core-shell interface, preventing structural ambiguity caused by interdiffusion between the core and shell layers at high temperatures, thus guaranteeing the stability of the core-shell structure during long-term electrolysis.

[0018] The surface layer is prepared using a rare-earth-doped PbO2 coating via electrodeposition. Rare-earth doping refines the PbO2 grain size, significantly increasing the specific surface area of ​​the coating and resulting in a substantial reduction in the actual current density at the same geometric current density. This mitigates electrode polarization and extends the coating's lifespan. After rare-earth ions enter the PbO2 lattice through substitution doping, the difference in ionic radius causes lattice distortion and pinning effects, effectively inhibiting the coarsening and growth of PbO2 grains during long-term operation, maintaining the coating's high activity and stability. Simultaneously, rare-earth doping can also modulate the electronic structure of PbO2, reducing the overpotential of the oxygen evolution reaction (OER) and decreasing electrolysis energy consumption. Compared to traditional pure PbO2 coatings, the rare-earth-doped surface layer exhibits higher OER catalytic activity, longer lifespan, and better corrosion resistance.

[0019] The beneficial effects of this invention are: This invention achieves functional zoning and performance synergy from the titanium substrate to the coating surface through a multi-layer gradient design consisting of a laser-nitrided layer, a bottom layer, an intermediate layer, and a rare-earth-doped surface layer. First, the laser-nitrided layer solves the problems of substrate passivation and interface peeling, providing a stable metallurgical bonding substrate for the upper oxide coating. The bottom layer adopts an IrO2-Ta2O5 composite system, which, after thermal decomposition, forms a composite structure with high catalytic activity, high chemical stability, and good conductivity. The intermediate layer contains highly conductive PdO... x The nanonucleus constructs an electron transport pathway, and the IrO2-Ta2O5 shell provides both auxiliary catalytic activity and protects the core from corrosion, achieving a balance between high conductivity and high corrosion resistance. The surface layer is doped with rare earth PbO2, which refines the grains and generates a lattice pinning effect, significantly increasing the specific surface area, reducing the oxygen evolution overpotential, and inhibiting grain coarsening during long-term operation. Attached Figure Description

[0020] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0021] Figure 1This is the enhanced life curve of the titanium anode in Example 1 of the present invention; Figure 2 This is the enhanced lifespan curve of the titanium anode in Comparative Example 1 of this invention; Figure 3 These are the cyclic voltammetry curves of the titanium anodes in Examples 1-3 of this invention. Detailed Implementation

[0022] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0023] It should be noted that, unless otherwise specified, the present invention does not specifically limit the source of the raw materials used in the following embodiments. Commercially available products or products prepared by conventional preparation methods that are well known to those skilled in the art can be used. Experimental methods that do not specify specific conditions are all conventional methods and conventional conditions well known in the art.

[0024] Example 1

[0025] A method for preparing a long-life titanium anode for electrolytic copper foil production, the method comprising the following steps: S5-1, Pretreatment of titanium substrate: Take industrial-grade pure titanium plates and perform the following treatments in sequence: Sandblasting: Sandblasting is performed using 80-mesh white corundum sand at a pressure of 0.6 MPa, resulting in a surface roughness Ra of 8 μm. Acid etching treatment: The sandblasted titanium substrate is immersed in a 9wt% oxalic acid solution and ultrasonically treated at 70℃ for 1.5h. After removal, it is rinsed with deionized water and dried to obtain the pretreated titanium substrate. S5-2, Laser Nitriding Treatment: A fiber laser was used to scan the pretreated titanium substrate in a nitrogen atmosphere. The process parameters were: laser power 800W, scanning speed 300mm / min, spot diameter 4mm, nitrogen flow rate 30L / min, and nitrogen purity 99.99%. A laser nitriding layer with a thickness of 6.5μm was generated in situ on the titanium surface.

[0026] S5-3, Preparation of the base layer: Iridic acid and tantalum ethoxide were dissolved in isopropanol at a molar ratio of Ir:Ta = 4:2.5, and the total concentration of metal ions was adjusted to 0.3 mol / L to obtain the bottom precursor solution. The bottom precursor solution was uniformly coated onto the surface of the laser nitriding layer by brush coating, dried at 90℃ for 10 min, and then transferred to a muffle furnace to be heated to 510℃ and held for 1.5 h. After cooling, the coating-drying-thermal decomposition process was repeated for a total of 8 coatings to obtain the bottom layer.

[0027] S5-4. Preparation of the intermediate layer: S5-41. Dissolve palladium chloride in ethanol to a concentration of 0.1 mol / L to obtain a palladium-containing precursor solution. Coat the bottom surface with the palladium-containing precursor solution, dry at 90℃ for 10 min, and then place it in a muffle furnace to heat to 460℃ and hold for 1.5 h to form PdO. x Nanoparticle core; S5-42. Iridic acid and tantalum ethoxide were dissolved in isopropanol at a molar ratio of Ir:Ta = 7:3, with a total metal ion concentration of 0.2 mol / L, to obtain a precursor solution containing iridium and tantalum. The above solution was then coated onto a PdO4 substrate. x The surface of the core is dried at 90°C for 10 min, then placed in a muffle furnace and heated to 480°C and held for 1.5 h. The above S5-41 and S5-42 operations are repeated 4 times to obtain the intermediate layer. S5-5, Preparation of the surface layer: Preparation of electrodeposition plating solution: lead acetate 150g / L, nitric acid 35g / L, polyethylene glycol 25g / L, polyvinylpyrrolidone 2.5g / L, cerium nitrate 4g / L.

[0028] The plating solution was heated to 60°C and stirred until completely dissolved. A titanium substrate coated with an underlayer and intermediate layer was used as the anode plate, and a pure titanium plate was used as the cathode plate, with a distance of 10 cm between the anode and cathode. The substrate was immersed in the electroplating solution at a current density of 180 A / m. 2 Under certain conditions, an electrodeposition layer is formed for 35 minutes to obtain the long-life titanium anode.

[0029] Example 2

[0030] The only difference between this embodiment and Embodiment 1 is that the laser power in the laser nitriding process is 500W, the scanning speed is 100mm / min, the spot diameter is 3mm, and the nitrogen flow rate is 20L / min. All other aspects are the same as in Embodiment 1.

[0031] Example 3

[0032] The only difference between this embodiment and Embodiment 1 is that the laser power in the laser nitriding process is 1000W, the scanning speed is 500mm / min, the spot diameter is 5mm, and the nitrogen flow rate is 50L / min. All other aspects are the same as in Embodiment 1.

[0033] Example 4

[0034] The only difference between this embodiment and Embodiment 1 is that the molar ratio of Ir:Ta in the underlying layer is 3:2, while all other aspects are the same as in Embodiment 1.

[0035] Example 5

[0036] The only difference between this embodiment and Embodiment 1 is that the molar ratio of Ir:Ta in the bottom layer is 5:3, while all other aspects are the same as in Embodiment 1.

[0037] Example 6

[0038] The only difference between this embodiment and Embodiment 1 is that the electrodeposition plating solution is composed of 100 g / L lead acetate, 35 g / L nitric acid, 25 g / L polyethylene glycol, 2.5 g / L polyvinylpyrrolidone, and 4 g / L cerium nitrate. All other components are the same as in Embodiment 1.

[0039] Example 7

[0040] The only difference between this embodiment and Embodiment 1 is that the electrodeposition plating solution is composed of 200 g / L lead acetate, 35 g / L nitric acid, 25 g / L polyethylene glycol, 2.5 g / L polyvinylpyrrolidone, and 4 g / L cerium nitrate. All other components are the same as in Embodiment 1.

[0041] Comparative Example 1 The only difference between this comparative example and Example 1 is that the laser nitriding treatment is omitted; otherwise, they are the same as Example 1.

[0042] Comparative Example 2 The only difference between this comparative example and Example 1 is that the intermediate layer is prepared using a blended rather than a core-shell structure. Specifically, the precursors of Ir, Ta, and Pd are mixed together in a mixed solvent of isopropanol and ethanol in a molar ratio of Ir:Ta:Pd = 5:2:3. All other aspects are the same as in Example 1.

[0043] Comparative Example 3 The only difference between this comparative example and Example 1 is that rare earth elements are not added during surface electrodeposition; otherwise, they are the same as in Example 1.

[0044] Performance testing Oxygen evolution overpotential test The test system was a three-electrode system: the working electrode was the anode sample to be tested, the counter electrode was a platinum sheet electrode, the reference electrode was a saturated calomel electrode, and the electrolyte was a 0.5 mol / L H₂SO₄ solution. The test procedure involved immersing the electrode to be tested in the electrolyte for 30 min to achieve a stable state, connecting it to an electrochemical workstation, and setting the scanning parameters as follows: scan range: 0–2 V vs. SCE, scan rate: 5 mV / s, test temperature: 25 ± 1 °C, recording the polarization curve, and reading the current density as 10 mA / cm². 2 The corresponding potential value is determined, and the oxygen evolution overpotential is calculated.

[0045] Enhanced lifespan testing Test conditions: Electrolyte: 1.0 mol / L H2SO4 solution, Current density: 4 A / cm² 2Temperature: 50±1℃, Anode-cathode distance: 20 mm, Counter electrode: Platinum sheet. Test procedure: Fix the anode sample to be tested relative to the cathode, immerse it in the electrolyte, connect the DC power supply, and adjust the current to the set value (2 A / cm). 2 ), continuously record the cell voltage change curve over time, replace the electrolyte regularly (once every 24 hours), keep the test conditions stable, and when the cell voltage rises above 9.5 V, it is considered as anode failure, and record the cumulative running time.

[0046]

[0047] The data above shows that the enhanced lifetime of Example 1 is 52% higher than that of Comparative Example 1, indicating that the laser nitriding layer is the key structure for solving substrate passivation; the enhanced lifetime of Example 1 is 28% higher than that of Comparative Example 2, indicating that the core-shell structure of the intermediate layer achieves a balance between high conductivity and high corrosion resistance; the enhanced lifetime of Example 1 is 23% higher than that of Comparative Example 3, indicating that the rare earth doped surface layer effectively suppresses PbO2 grain coarsening and maintains long-lasting activity.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A long-life titanium anode for the production of electrolytic copper foil, characterized in that, The long-life titanium anode includes: Titanium substrate; A laser nitriding layer formed on the surface of the titanium substrate; A composite coating is formed on the surface of the laser nitrided layer, the composite coating comprising, from the inside out, a base layer, an intermediate layer and a surface layer; The bottom layer is an IrO2-Ta2O5 composite oxide coating. The intermediate layer is IrO2-Ta2O5-PdO x Composite oxide coating, The surface layer is a PbO2 coating doped with rare earth elements.

2. The long-life titanium anode for electrolytic copper foil production according to claim 1, characterized in that, The thickness of the laser nitrided layer is 5~8μm.

3. The long-life titanium anode for electrolytic copper foil production according to claim 1, characterized in that, The intermediate layer is IrO2-Ta2O5-PdO x With PdO x The core is composed of nanoparticles, with an oxidation stoichiometry x ranging from 1.2 to 1.

8. IrO2 and Ta2O5 are present in PdO. x A coating layer is formed on the surface.

4. A long-life titanium anode for electrolytic copper foil production according to claim 1, characterized in that, The rare earth element doped in the surface layer is Ce.

5. A method for preparing a long-life titanium anode for electrolytic copper foil production as described in any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: S5-1. Titanium substrate pretreatment: The titanium substrate is subjected to sandblasting and acid etching treatment in sequence to obtain a pretreated titanium substrate. S5-2, Laser nitriding treatment: The pretreated titanium substrate is scanned in a nitrogen atmosphere using a laser beam to obtain a laser nitriding layer; S5-3. Preparation of the bottom layer: Coat the surface of the laser nitrided layer with a precursor solution containing Ir and Ta, dry it at 80~100℃, and then place it in a muffle furnace to heat to 500~520℃ and keep it at that temperature for 1~2 h to obtain the bottom layer. S5-4. Preparation of intermediate layer: Coating with a precursor solution containing Pd, drying at 80~100℃, then placing in a muffle furnace and heating to 450~480℃ and holding for 1~2 h, then coating with a precursor solution containing Ir and Ta, drying at 80~100℃, then placing in a muffle furnace and heating to 470~490℃ and holding for 1~2 h to obtain the intermediate layer; S5-5, Surface preparation: Heat the electroplating solution to 50~70℃, place the titanium substrate after step S5-4 as the anode plate into the electroplating solution, use a pure titanium plate as the cathode material, and the distance between the anode and the cathode is 10±0.5cm. Deposit the surface layer by electrodeposition to obtain the long-life titanium anode.

6. The method for preparing a long-life titanium anode for electrolytic copper foil production according to claim 5, characterized in that, In step S5-1, the surface roughness Ra is 5-10 μm by sandblasting; the acid etching process involves immersing the titanium substrate in an 8-10 wt% oxalic acid solution and ultrasonicating it at 60-80°C for 1-2 hours.

7. The method for preparing a long-life titanium anode for electrolytic copper foil production according to claim 5, characterized in that, In the laser nitriding process, the laser power is 500~1000W, the scanning speed is 100~500mm / min, the spot diameter is 3~5mm, the nitrogen flow rate is 20~50L / min, and the nitrogen purity is ≥99.9%.

8. The method for preparing a long-life titanium anode for electrolytic copper foil production according to claim 5, characterized in that, The molar ratio of Ir to Ta in the bottom layer is (3~5):(2~3).

9. A method for preparing a long-life titanium anode for electrolytic copper foil production according to claim 5, characterized in that, The molar ratio of Ir, Ta and Pd in ​​the intermediate layer is (4~6):(1~3):(2~4).

10. A method for preparing a long-life titanium anode for electrolytic copper foil production according to claim 5, characterized in that, The electrodeposition bath composition is as follows: lead acetate 100~200 g / L, nitric acid 30~40 g / L, polyethylene glycol 20~30 g / L, polyvinylpyrrolidone 2~3 g / L, and soluble salts of rare earth elements 3~5 g / L; the electrodeposition current density is 150~200 A / m. 2 The deposition time is 30-40 min.

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