Formation method suitable for composite aluminum foil

Abstract

The invention relates to the technical field of electrode foil manufacturing, in particular to a formation method suitable for a composite aluminum foil. According to the formation method of the composite aluminum foil, the corrosion foil is sequentially subjected to heat treatment, formation treatment, passivation treatment, two times of heat treatment and formation repair treatment, and finally, the TEOS-28 / TEOS-40 mixed silicon source solution is adopted for dipping treatment, so that a composite oxide layer with high dielectric constant and excellent hydration resistance is constructed on the surface of the aluminum foil; the problem that the hydration resistance and the specific volume of the TiO2-Al composite corrosion foil prepared by an atomic deposition method are reduced due to defects in the formation process is solved. Compared with a traditional process, the method has the advantages that high specific volume is kept, pressure resistance and hydration resistance are remarkably improved, and a reliable technical scheme is provided for manufacturing of the high-performance aluminum electrolytic capacitor.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode foil manufacturing, in particular to a chemical formation method suitable for composite aluminum foil. Background Art

[0002] In the field of modern electronic component manufacturing, aluminum electrolytic capacitors are key electronic components, and their performance directly affects the reliability and service life of electronic devices. However, with the increasing use and popularity of capacitors, it is difficult for a single dielectric material to simultaneously meet the requirements of high specific capacitance and high withstand voltage. To this end, more and more research is focusing on doping metal oxides with high dielectric constants into the aluminum oxide layer of electrode foil to increase the specific capacitance of the electrode foil.

[0003] Atomic deposition (ALD) offers significant advantages in preparing TiO2 composite aluminum foil, including high precision and uniformity, high density and good adhesion, controllable composition and structure, low-temperature deposition, environmental friendliness, and scalability. These advantages enable ALD technology to produce high-quality, high-performance TiO2 composite aluminum foil. However, during the formation process, the introduction of TiO2 may alter the crystal structure and chemical stability of Al2O3, introducing more defects and resulting in reduced hydration resistance in the final product.

[0004] To this end, we have made improvements to the original chemical formation process in the hope of repairing the defects in the oxide film and further improving the product's hydration resistance and specific capacitance. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to propose a chemical formation method suitable for composite aluminum foil to solve the problem that the TiO2-Al composite corrosion foil prepared by atomic deposition method has defects during chemical formation, which leads to a decrease in the hydration resistance and specific volume of the final product.

[0006] Based on the above purpose, the present invention provides a chemical formation method suitable for composite aluminum foil, comprising the following steps: S1: Preparation of TiO2-Al corrosion foil; S2: heat treating the TiO2-Al corrosion foil; S3: performing chemical conversion treatment on the heat-treated corroded foil; S4: The corroded foil after chemical conversion treatment is sequentially subjected to passivation treatment, first heat treatment, chemical conversion repair treatment, first heat treatment, and finally immersed in an ethyl silicate mixed solution and dried; Preferably, the ethyl silicate mixed solution in step S4 is a mixed solution of 0.1%-0.3% TEOS-28 and 0.1%-0.4% TEOS-40.

[0007] Preferably, the TiO2-Al etching foil in step S1 is obtained by depositing a TiO2 thin film on the surface of the aluminum etching foil by an atomic deposition method.

[0008] Preferably, the atomic deposition method uses an ethanol-cleaned aluminum foil as a substrate, TTIP as a first precursor, and pure water as a second precursor for deposition.

[0009] Preferably, the thickness of the TiO2 film is 2-12 nm.

[0010] Preferably, the heat treatment in step S2 is performed in a muffle furnace at a temperature of 300-550° C. for a treatment time of 10-60 min.

[0011] Preferably, the specific steps of the chemical conversion treatment in step S3 are as follows: placing the heat-treated corroded foil in an ammonium adipate solution with a temperature of 70-90°C and a concentration of 70-110 g / L, setting a DC power supply current density of 0.1 A / cm 2 , increasing the voltage step by step, and performing four-stage formation treatment.

[0012] Preferably, the passivation treatment in step S4 is performed in a phosphoric acid solution with a temperature of 50-75° C. and a concentration of 45-80 g / L, and the passivation time is 1-5 min.

[0013] Preferably, the temperature of the first heat treatment in step S4 is 300-450° C., and the time is 1-10 minutes.

[0014] Preferably, the chemical repair treatment in step S4 is carried out in an ammonium adipate solution with a temperature of 70-90°C and a concentration of 80-120 g / L, and a chemical current density of 10-50 mA / cm 2 .

[0015] Preferably, the temperature of the second heat treatment in step S4 is 450-550° C., and the time is 1-5 minutes.

[0016] Preferably, the immersion time in step S4 is 1-5 minutes.

[0017] Preferably, the drying temperature in step S4 is 200-300° C., and the drying time is 1-3 minutes.

[0018] Beneficial effects of the present invention: The present invention adopts a mixed silicon source system, which can form a more stable three-dimensional silicon-oxygen network structure compared to a single TEOS-28 system or a single TEOS-28 system. The two work together to form a composite dielectric layer with a gradient distribution, which not only enhances the interfacial bonding between the dielectric layer and the substrate, but also ensures the uniformity and stability of the surface oxide film, forms a more effective barrier layer, inhibits the penetration and damage of water molecules to the dielectric layer, and improves key indicators such as voltage maintenance capability, specific volume retention rate and boost response speed.

[0019] The composite aluminum foil treated with TEOS-28 / TEOS-40 mixed silicon source in the present invention shows more significant advantages in dielectric property stability compared with samples not treated with silicate and sodium silicate system. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0021] The specific preparation steps of the TiO2-Al corrosion foil used in the examples and comparative examples of the present invention are as follows: the aluminum corrosion foil is immersed in ethanol and ultrasonicated for 10 minutes, then blown dry with nitrogen, and then placed in an oven at 80°C for drying. The aluminum corrosion foil is then placed in a reaction chamber and evacuated to a pressure of ≤10 -3 Torr, and heat to 150-200℃; the pressure is increased to 0.1-0.5 Torr, and TTIP vapor (carrier gas is N2, flow rate 50sccm) is introduced for 1-2s; then high-purity nitrogen is introduced for purging, which lasts for 10s; then deionized water vapor is injected for oxidation pulse, which lasts for 0.5-1s; then high-purity nitrogen is introduced again for purging, which lasts for 10s. The above steps are repeated for treatment. After the deposition is completed, the TiO2-Al corrosion foil is obtained after cooling.

[0022] Example 1: A chemical formation method suitable for composite aluminum foil, the specific steps are as follows: (1) Preparation of TiO2-Al corrosion foil by atomic deposition method; (2) placing the etched foil obtained in step (1) in a muffle furnace at 300°C for 10 minutes; (3) Place the heat-treated corroded foil in a 70g / L ammonium adipate solution at 70°C and a current density of 0.1A / cm 2 , carry out four-level formation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a temperature of 50°C and a concentration of 45g / L for passivation treatment for 1 min, followed by heat treatment at 300°C for 1 min, and then placed in an ammonium adipate solution with a temperature of 70°C and a concentration of 80g / L, with a DC power supply current density of 10mA / cm 2 , repair and chemical treatment were carried out, and after heat treatment at 450℃ for 1min, it was immersed in a mixed solution of 0.1% TEOS-28 and 0.1% TEOS-40 for 1in, and then taken out and dried at 200℃ for 1min.

[0023] Example 2: A chemical formation method suitable for composite aluminum foil, the specific steps are as follows: (1) Preparation of TiO2-Al corrosion foil by atomic deposition method; (2) placing the etched foil obtained in step (1) in a muffle furnace at 500°C for 30 minutes; (3) Place the heat-treated corroded foil in a 90 g / L ammonium adipate solution at 80°C and a current density of 0.1 A / cm 2 , carry out four-level formation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution at a temperature of 65°C and a concentration of 60 g / L for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution at a temperature of 80°C and a concentration of 100 g / L, with a DC power supply current density of 30 mA / cm 2 , repaired and chemically processed, after heat treatment at 500℃ for 3 minutes, immersed in a mixed solution of 0.2% TEOS-28 and 0.3% TEOS-40 for 3 minutes, taken out and dried at 250℃ for 2 minutes.

[0024] Example 3: A chemical formation method suitable for composite aluminum foil, the specific steps are as follows: (1) Preparation of TiO2-Al corrosion foil by atomic deposition method; (2) placing the etched foil from step (1) in a muffle furnace at 550°C for 60 minutes; (3) Place the heat-treated corroded foil in a 110 g / L ammonium adipate solution at 90°C and a current density of 0.1 A / cm 2 , carry out four-level formation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a temperature of 75°C and a concentration of 80 g / L for passivation treatment for 5 min, followed by heat treatment at 450°C for 10 min, and then placed in an ammonium adipate solution with a temperature of 90°C and a concentration of 120 g / L, with a DC power supply current density of 50 mA / cm 2 , repair and chemical treatment were carried out, and after heat treatment at 550℃ for 5 minutes, it was immersed in a mixed solution of 0.3% TEOS-28 and 0.4% TEOS-40 for 5 minutes. After being taken out, it was placed at 200-300℃ for drying for 3 minutes.

[0025] Comparative Example 1: The difference from Example 2 is that the mixed solution of 0.2% TEOS-28 and 0.3% TEOS-40 is replaced by 0.5% TEOS-28 solution. The remaining steps are the same as Example 2. The specific steps are as follows: (1) Preparation of TiO2-Al corrosion foil by atomic deposition method; (2) placing the etched foil obtained in step (1) in a muffle furnace at 500°C for 30 minutes; (3) Place the heat-treated corroded foil in a 90 g / L ammonium adipate solution at 80°C and a current density of 0.1 A / cm 2 , carry out four-level formation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution at a temperature of 65°C and a concentration of 60 g / L for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution at a temperature of 80°C and a concentration of 100 g / L, with a DC power supply current density of 30 mA / cm 2 , repaired and chemically processed, after heat treatment at 500℃ for 3 minutes, immersed in 0.5% TEOS-28 solution for 3 minutes, taken out and dried at 250℃ for 2 minutes.

[0026] Comparative Example 2: The difference from Example 2 is that the mixed solution of 0.2% TEOS-28 and 0.3% TEOS-40 is replaced with a 0.5% TEOS-40 solution. The remaining steps are the same as Example 2. The specific steps are as follows: (1) Preparation of TiO2-Al corrosion foil by atomic deposition method; (2) placing the etched foil obtained in step (1) in a muffle furnace at 500°C for 30 minutes; (3) Place the heat-treated corroded foil in a 90 g / L ammonium adipate solution at 80°C and a current density of 0.1 A / cm 2 , carry out four-level formation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution at a temperature of 65°C and a concentration of 60 g / L for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution at a temperature of 80°C and a concentration of 100 g / L, with a DC power supply current density of 30 mA / cm 2 , repaired and chemically processed, after heat treatment at 500℃ for 3 minutes, immersed in 0.5% TEOS-40 solution for 3 minutes, taken out and dried at 250℃ for 2 minutes.

[0027] Comparative Example 3: The difference from Example 2 is that the silicate solution is not impregnated. The remaining steps are the same as Example 2. The specific steps are as follows: (1) Preparation of TiO2-Al corrosion foil by atomic deposition method; (2) placing the etched foil obtained in step (1) in a muffle furnace at 500°C for 30 minutes; (3) Place the heat-treated corroded foil in a 90 g / L ammonium adipate solution at 80°C and a current density of 0.1 A / cm 2 , carry out four-level formation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution at a temperature of 65°C and a concentration of 60 g / L for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution at a temperature of 80°C and a concentration of 100 g / L, with a DC power supply current density of 30 mA / cm 2 , repair and chemical treatment were carried out, and then heat treated at 500℃ for 3 minutes.

[0028] Comparative Example 4: The difference from Example 2 is that the mixed solution of 0.2% TEOS-28 and 0.3% TEOS-40 is replaced with 0.5% sodium silicate solution. The remaining steps are the same as Example 2. The specific steps are as follows: (1) Preparation of TiO2-Al corrosion foil by atomic deposition method; (2) placing the etched foil obtained in step (1) in a muffle furnace at 500°C for 30 minutes; (3) Place the heat-treated corroded foil in a 90 g / L ammonium adipate solution at 80°C and a current density of 0.1 A / cm 2 , carry out four-level formation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution at a temperature of 65°C and a concentration of 60 g / L for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution at a temperature of 80°C and a concentration of 100 g / L, with a DC power supply current density of 30 mA / cm 2 , repair and chemical treatment were carried out, and then heat treated at 500℃ for 3 minutes, immersed in 0.5% sodium silicate solution for 3 minutes, taken out and dried at 250℃ for 2 minutes.

[0029] Performance Testing Specific volume: measured using a specific volume tester according to EIAJ RC-2364A standard method; Hydration resistance: The samples obtained in the examples and comparative examples were kept in pure water at 100°C for 12 hours, and the rise time was measured according to the Tr / Vt test method; Boiling durability test: The samples were immersed in boiling water (100°C) for 1 hour. After removal, the above test was repeated. The test results are shown in Table 1.

[0030] Table 1 Performance test results

[0031] Data Analysis: Performance test data from Examples 1-3 demonstrate that the composite aluminum foil prepared by the present invention exhibits excellent overall performance. The mixed silicon source (TEOS-28 / TEOS-40) forms a nanoscale distributed aluminum silicate network, which not only rapidly penetrates the submicron pores of the corroded foil to repair surface defects but also constructs a dense, three-dimensional, cross-linked Si-O-Si framework. This multi-scale composite dielectric layer maintains the high voltage resistance of aluminum oxide while significantly inhibiting hydration through the chemical stability of silicon-oxygen bonds. Furthermore, the synergistic polarization effect of [SiO4] tetrahedra and [AlO6] octahedra in the aluminum silicate optimizes the low-frequency electric field response, significantly shortening the voltage rise time. Ultimately, this achieves simultaneous improvements in voltage resistance, specific volume, and water resistance.

[0032] From the comparison of the performance test data of Example 2 and Comparative Examples 1 and 2, it can be seen that the composite aluminum foil modified with a TEOS-28 / TEOS-40 mixed silicon source shows significant advantages in dielectric performance stability and structural integrity. Compared with a single TEOS-28 system or a single TEOS-28 system, the mixed silicon source system has improved key indicators such as voltage maintenance capability, specific volume retention rate and boost response speed. This difference may be due to the synergistic mechanism of the two silicon sources in the construction of the dielectric layer: TEOS-28 can quickly penetrate into the nano-scale defects on the surface of the oxide film, while the high polymerization degree of TEOS-40 forms a more stable three-dimensional silicon-oxygen network structure during the subsequent heat treatment process. The two work together to form a composite dielectric layer with a gradient distribution. On the one hand, this structure enhances the interfacial bonding between the dielectric layer and the substrate through the chemical bonding of aluminum silicate, and on the other hand, the high stability of the silicon-oxygen bond suppresses the structural degradation of the dielectric layer in a wet and hot environment, ensuring the uniformity and stability of the surface oxide film, forming a more effective barrier layer, and suppressing the penetration and damage of water molecules to the dielectric layer. This multi-scale dielectric layer structure constructed by mixing silicon sources reflects the synergistic regulatory effect of components on material properties.

[0033] Comparison of the performance test data of Example 2 with Comparative Examples 3 and 4 shows that the composite aluminum foil treated with the TEOS-28 / TEOS-40 mixed silicon source exhibits a more significant advantage in dielectric stability compared to the sample without silicate treatment and the sodium silicate system. This performance difference may be due to the synergistic effect of the two silicon sources to form a composite dielectric layer with gradient properties. This structure enhances the overall density of the dielectric layer through the chemical stability of the silicon-oxygen bond, while optimizing the space charge distribution. At the same time, under hot and humid environmental conditions, its hydrophobic properties can inhibit water molecule penetration, thereby maintaining the stability of the dielectric properties.

[0034] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A chemical formation method suitable for composite aluminum foil, characterized in that: The following steps are involved: S1: Preparation of TiO2-Al corrosion foil; S2: heat treating the TiO2-Al corrosion foil; S3: performing chemical conversion treatment on the heat-treated corroded foil; S4: The corroded foil after chemical conversion treatment is sequentially subjected to passivation treatment, first heat treatment, chemical conversion repair treatment, first heat treatment, and finally immersed in an ethyl silicate mixed solution and dried; The ethyl silicate mixed solution in step S4 is a mixed solution of 0.1%-0.3% TEOS-28 and 0.1%-0.4% TEOS-40.

2. The chemical formation method for composite aluminum foil according to claim 1, characterized in that: The TiO2-Al etching foil in step S1 is obtained by depositing a TiO2 film on the surface of the aluminum etching foil by an atomic deposition method, wherein the thickness of the TiO2 film is 2-12 nm.

3. The chemical formation method suitable for composite aluminum foil according to claim 1, characterized in that: The heat treatment temperature in step S2 is 300-550° C., and the treatment time is 10-60 min.

4. The chemical formation method for composite aluminum foil according to claim 1, characterized in that: The specific steps of the formation treatment in step S3 are as follows: The heat-treated corroded foil was placed in an ammonium adipate solution with a temperature of 70-90°C and a concentration of 70-110 g / L. The DC power supply current density was set to 0.1 A / cm 2 , and undergo four-level chemical treatment.

5. The chemical formation method for composite aluminum foil according to claim 1, characterized in that: The passivation treatment in step S4 is carried out in a phosphoric acid solution at a temperature of 50-75° C. and a concentration of 45-80 g / L, and the passivation time is 1-5 minutes.

6. The chemical formation method for composite aluminum foil according to claim 1, characterized in that: The temperature of the first heat treatment is 300-450° C., and the time is 1-10 minutes; the temperature of the second heat treatment is 450-550° C., and the time is 1-5 minutes.

7. The chemical formation method for composite aluminum foil according to claim 1, characterized in that: The chemical repair treatment in step S4 is carried out in an ammonium adipate solution with a temperature of 70-90°C and a concentration of 80-120 g / L, and a chemical current density of 10-50 mA / cm 2 .

8. The chemical formation method for composite aluminum foil according to claim 1, characterized in that: The immersion time in step S4 is 1-5 minutes.

9. The chemical formation method for composite aluminum foil according to claim 1, characterized in that: The drying temperature in step S4 is 200-300° C. and the drying time is 1-3 minutes.

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