A formation method suitable for composite aluminum foil

Abstract

The present application relates to the technical field of electrode foil manufacturing, and particularly relates to a formation method suitable for composite aluminum foil. The formation method of the composite aluminum foil of the present application, after the etching foil is sequentially subjected to heat treatment, formation treatment, passivation treatment, twice heat treatment and formation repair treatment, finally adopts TEOS-28 / TEOS-40 mixed silicon source solution for impregnation treatment, builds a composite oxide layer with high dielectric constant and excellent hydration resistance on the surface of the aluminum foil, solves the problem of the decrease of the hydration resistance and specific capacity of the TiO2-Al composite etching foil prepared by the atomic deposition method due to defects in the formation process. Compared with the traditional process, the present application significantly improves the voltage resistance and hydration resistance while maintaining high specific capacity, and provides a reliable technical solution for the manufacturing of high-performance aluminum electrolytic capacitors.

Description

Technical Field

[0001] This invention relates to the field of electrode foil manufacturing technology, and more particularly to a formation method suitable for composite aluminum foil. Background Technology

[0002] In the field of modern electronic component manufacturing, aluminum electrolytic capacitors are key electronic components whose performance directly affects the reliability and lifespan of electronic devices. However, with the continuous use and widespread adoption of capacitors, a single dielectric material can hardly meet the requirements of high specific capacitance and high withstand voltage at the same time. Therefore, more and more research focuses on doping the aluminum oxide layer of the electrode foil with metal oxides with high dielectric constants to improve the specific capacitance of the electrode foil.

[0003] Atomic deposition (ALD) offers significant advantages in the preparation of TiO2 composite aluminum foils, 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 foils. However, during the formation process, the introduction of TiO2 may alter the crystal structure and chemical stability of Al2O3, introducing more defects and leading to a decrease in the hydration resistance of the final product.

[0004] Therefore, we have made improvements to the original formation process in order to repair defects in the oxide film and further improve the product's hydration resistance and specific capacitance. Summary of the Invention

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

[0006] To achieve the above objectives, the present invention provides a formation method suitable for composite aluminum foil, comprising the following steps: S1: Preparation of TiO2-Al etched foil; S2: Heat-treat the TiO2-Al etched foil; S3: The heat-treated etched foil undergoes a formation process; S4: The etched foil after the formation treatment is subjected to passivation treatment, first heat treatment, formation repair treatment, first heat treatment, and finally immersed in a mixed solution of ethyl silicate 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 corrosion foil in step S1 is obtained by depositing a TiO2 thin film on the surface of an aluminum corrosion foil using atomic deposition.

[0008] Preferably, the atomic deposition method uses ethanol-cleaned aluminum etched 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 carried out in a muffle furnace at a temperature of 300-550°C for a time of 10-60 minutes.

[0011] Preferably, the specific steps of the formation treatment in step S3 are as follows: The heat-treated etched foil is placed in an ammonium adipate solution at a temperature of 70-90°C and a concentration of 70-110 g / L, and the DC power supply current density is set to 0.1 A / cm². 2 The voltage is gradually increased to perform a four-stage formation process.

[0012] Preferably, 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 min.

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

[0014] Preferably, the chemical formation repair treatment in step S4 is carried out in an ammonium adipate solution at a temperature of 70-90℃ and a concentration of 80-120 g / L, with a chemical formation current density of 10-50 mA / cm². 2 .

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

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

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

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

[0019] The composite aluminum foil treated with a TEOS-28 / TEOS-40 mixed silicon source exhibits a significant advantage in dielectric stability compared to samples without silicate treatment and sodium silicate systems. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0021] The specific preparation steps of the TiO2-Al etched foil used in the embodiments and comparative examples of this invention are as follows: The aluminum etched foil is immersed in ethanol and sonicated for 10 min, then dried with nitrogen gas and placed in an 80℃ oven for drying. Then, the aluminum etched foil is placed in a reaction chamber and a vacuum is drawn until the pressure is ≤10. -3 The temperature is increased to 150-200℃ and the pressure is increased to 0.1-0.5 Torr. TTIP vapor (carrier gas is N2, flow rate 50 sccm) is introduced for 1-2 seconds. Then, high-purity nitrogen is introduced for purging for 10 seconds. Deionized water vapor is then injected for oxidation pulse for 0.5-1 seconds. Then, high-purity nitrogen is introduced again for purging for 10 seconds. The above steps are repeated. After deposition is completed, the material is cooled to obtain the TiO2-Al etched foil.

[0022] Example 1: A formation method suitable for composite aluminum foil, the specific steps of which are as follows: (1) TiO2-Al etched foil was prepared by atomic deposition; (2) The etched foil from step (1) is placed in a muffle furnace at 300°C for heat treatment for 10 minutes; (3) The heat-treated etched foil is placed in an ammonium adipate solution at 70°C and 70 g / L, with a current density of 0.1 A / cm. 2 Perform four-level transformation; (4) The aluminum foil obtained in step (3) is placed in a phosphoric acid solution with a concentration of 45 g / L at a temperature of 50°C 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 concentration of 80 g / L at a temperature of 70°C. The DC power supply current density is set to 10 mA / cm². 2 The repair process involves heat treatment at 450°C for 1 minute, followed by immersion in a mixed solution of 0.1% TEOS-28 and 0.1% TEOS-40 for 1 minute, and then drying at 200°C for 1 minute.

[0023] Example 2: A formation method suitable for composite aluminum foil, the specific steps of which are as follows: (1) TiO2-Al etched foil was prepared by atomic deposition; (2) The etched foil from step (1) is placed in a muffle furnace at 500°C for heat treatment for 30 minutes; (3) The heat-treated etched foil is placed in an ammonium adipate solution at 80℃ and a concentration of 90 g / L, with a current density of 0.1 A / cm. 2 Perform four-level transformation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a concentration of 60 g / L at a temperature of 65°C for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution with a concentration of 100 g / L at a temperature of 80°C. The DC power supply current density was set to 30 mA / cm². 2 The repair process involves heat treatment at 500℃ for 3 minutes, followed by immersion in a mixed solution of 0.2% TEOS-28 and 0.3% TEOS-40 for 3 minutes, and then drying at 250℃ for 2 minutes.

[0024] Example 3: A formation method suitable for composite aluminum foil, the specific steps of which are as follows: (1) TiO2-Al etched foil was prepared by atomic deposition; (2) The etched foil from step (1) is placed in a muffle furnace at 550°C for heat treatment for 60 minutes; (3) The heat-treated etched foil is placed in an ammonium adipate solution at 90℃ and a concentration of 110 g / L, with a current density of 0.1 A / cm. 2 Perform four-level transformation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a concentration of 80 g / L at a temperature of 75°C 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 concentration of 120 g / L at a temperature of 90°C. The DC power supply current density was set to 50 mA / cm². 2 The repair process involves heat treatment at 550℃ for 5 minutes, followed by immersion in a mixed solution of 0.3% TEOS-28 and 0.4% TEOS-40 for 5 minutes. After removal, the solution is dried at 200-300℃ 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 was replaced with a 0.5% TEOS-28 solution. The remaining steps are the same as in Example 2, and the specific steps are as follows: (1) TiO2-Al etched foil was prepared by atomic deposition; (2) The etched foil from step (1) is placed in a muffle furnace at 500°C for heat treatment for 30 minutes; (3) The heat-treated etched foil is placed in an ammonium adipate solution at 80℃ and a concentration of 90 g / L, with a current density of 0.1 A / cm. 2 Perform four-level transformation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a concentration of 60 g / L at a temperature of 65°C for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution with a concentration of 100 g / L at a temperature of 80°C. The DC power supply current density was set to 30 mA / cm². 2 The material is then repaired and processed, heat-treated at 500℃ for 3 minutes, then immersed in 0.5% TEOS-28 solution for 3 minutes, and finally 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 was replaced with a 0.5% TEOS-40 solution. The remaining steps are the same as in Example 2, and the specific steps are as follows: (1) TiO2-Al etched foil was prepared by atomic deposition; (2) The etched foil from step (1) is placed in a muffle furnace at 500°C for heat treatment for 30 minutes; (3) The heat-treated etched foil is placed in an ammonium adipate solution at 80℃ and a concentration of 90 g / L, with a current density of 0.1 A / cm. 2 Perform four-level transformation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a concentration of 60 g / L at a temperature of 65°C for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution with a concentration of 100 g / L at a temperature of 80°C. The DC power supply current density was set to 30 mA / cm². 2 The repair process involves heat treatment at 500℃ for 3 minutes, followed by immersion in a 0.5% TEOS-40 solution for 3 minutes, and then drying 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 in Example 2, as detailed below: (1) TiO2-Al etched foil was prepared by atomic deposition; (2) The etched foil from step (1) is placed in a muffle furnace at 500°C for heat treatment for 30 minutes; (3) The heat-treated etched foil is placed in an ammonium adipate solution at 80℃ and a concentration of 90 g / L, with a current density of 0.1 A / cm. 2 Perform four-level transformation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a concentration of 60 g / L at a temperature of 65°C for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution with a concentration of 100 g / L at a temperature of 80°C. The DC power supply current density was set to 30 mA / cm². 2 Repair and chemical formation are carried out, followed by heat treatment 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 was replaced with a 0.5% sodium silicate solution. The remaining steps are the same as in Example 2, and the specific steps are as follows: (1) TiO2-Al etched foil was prepared by atomic deposition; (2) The etched foil from step (1) is placed in a muffle furnace at 500°C for heat treatment for 30 minutes; (3) The heat-treated etched foil is placed in an ammonium adipate solution at 80℃ and a concentration of 90 g / L, with a current density of 0.1 A / cm. 2 Perform four-level transformation; (4) The aluminum foil obtained in step (3) was placed in a phosphoric acid solution with a concentration of 60 g / L at a temperature of 65°C for passivation treatment for 3 min, followed by heat treatment at 350°C for 5 min, and then placed in an ammonium adipate solution with a concentration of 100 g / L at a temperature of 80°C. The DC power supply current density was set to 30 mA / cm². 2 The material is then repaired and processed, heat-treated at 500℃ for 3 minutes, then immersed in a 0.5% sodium silicate solution for 3 minutes, and finally dried at 250℃ for 2 minutes.

[0029] Performance testing Specific volume: Determined using a specific volume tester according to the EIAJ RC-2364A standard method; Hydration resistance: The samples obtained from the examples and comparative examples were kept in pure water at 100°C for 12 hours, and the pressure rise time was determined according to the Tr / Vt test method. Water boiling durability test: Immerse the sample in boiling water (100℃) for 1 hour, and repeat the above test after taking it out. The test results are shown in Table 1.

[0030] Table 1 Performance Test Results

[0031] Data Analysis: Performance test data from Examples 1-3 show that the composite aluminum foil prepared in this invention exhibits excellent comprehensive performance. The mixed silicon source (TEOS-28 / TEOS-40) forms a nanoscale distributed aluminum silicate network, which can not only quickly penetrate into the submicron pores of the etched foil to repair surface defects, but also construct a three-dimensional cross-linked dense Si-O-Si framework. This multi-scale composite dielectric layer maintains the high voltage withstand characteristics of alumina, and significantly inhibits the hydration reaction through the chemical stability of silicon-oxygen bonds. Furthermore, it optimizes the low-frequency electric field response through the synergistic polarization effect of [SiO4] tetrahedra and [AlO6] octahedra in aluminum silicate, resulting in a significant reduction in voltage rise time. Ultimately, this achieves a simultaneous improvement in voltage withstand performance, specific capacitance characteristics, and water resistance.

[0032] A comparison of the performance test data from Example 2 with Comparative Examples 1 and 2 shows that the composite aluminum foil modified with a TEOS-28 / TEOS-40 mixed silicon source exhibits significant advantages in dielectric stability and structural integrity. Compared to a single TEOS-28 system, the mixed silicon source system demonstrates improvements in key indicators such as withstand voltage retention, specific capacitance retention, and boost response speed. This difference may stem from the synergistic effect of the two silicon sources in the dielectric layer construction: TEOS-28 can rapidly penetrate into nanoscale defects on the oxide film surface, while the high polymerization degree of TEOS-40 forms a more stable three-dimensional silicon-oxygen network structure during subsequent heat treatment. Together, they form a composite dielectric layer with a gradient distribution. This structure, on the one hand, enhances the interfacial bonding between the dielectric layer and the substrate through the chemical bonding of aluminum silicate; on the other hand, the high stability of the silicon-oxygen bonds inhibits the structural degradation of the dielectric layer under humid and hot conditions, ensuring the uniformity and stability of the surface oxide film and forming a more effective barrier layer that inhibits the penetration and damage of water molecules into the dielectric layer. This multi-scale dielectric layer structure, constructed using a hybrid silicon source, demonstrates the synergistic effect of components on the regulation of material properties.

[0033] A comparison of the performance test data from Example 2 and Comparative Examples 3 and 4 shows that the composite aluminum foil treated with the TEOS-28 / TEOS-40 mixed silicon source exhibits a significant advantage in dielectric stability compared to the untreated silicate sample and the sodium silicate system. This performance difference may stem from the synergistic effect of the two silicon sources, which forms a composite dielectric layer with gradient characteristics. This structure enhances the overall compactness of the dielectric layer through the chemical stability of silicon-oxygen bonds, optimizes the space charge distribution, and, under humid and hot conditions, inhibits water molecule penetration through its hydrophobic properties, thereby maintaining the stability of dielectric properties.

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

Claims

1. A formation method suitable for composite aluminum foil, characterized in that, Includes the following steps: S1: Preparation of TiO2-Al etched foil; S2: Heat-treat the TiO2-Al etched foil; S3: The heat-treated etched foil undergoes a formation process; S4: The etched foil after the formation treatment is subjected to passivation treatment, first heat treatment, formation repair treatment, second heat treatment, and finally immersed in a mixed solution of ethyl silicate and dried. The tetraethyl orthosilicate mixed solution mentioned in step S4 is a mixed solution of 0.1%-0.3% TEOS-28 and 0.1%-0.4% TEOS-40.

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

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

4. The formation method for composite aluminum foil according to claim 1, characterized in that, The specific steps of the formation process described in step S3 are as follows: The heat-treated etched foil was placed in an ammonium adipate solution at a temperature of 70-90℃ and a concentration of 70-110 g / L, with a DC power supply current density of 0.1 A / cm². 2 It undergoes a four-stage formation process.

5. The 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 with a temperature of 50-75℃ and a concentration of 45-80g / L, and the passivation time is 1-5min.

6. The formation method for composite aluminum foil according to claim 1, characterized in that, The first heat treatment is performed at a temperature of 300-450℃ for 1-10 minutes; the second heat treatment is performed at a temperature of 450-550℃ for 1-5 minutes.

7. The formation method for composite aluminum foil according to claim 1, characterized in that, The formation repair treatment described in step S4 is carried out in an ammonium adipate solution at a temperature of 70-90℃ and a concentration of 80-120 g / L, with a formation current density of 10-50 mA / cm². 2 .

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

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

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