A method for preparing an aluminum electrolytic capacitor cathode foil with improved uniformity of corrosion

Abstract

The application discloses a preparation method of an aluminum electrolytic capacitor cathode foil with improved corrosion uniformity, which comprises seven steps of raw material selection and pretreatment, ingot preparation, hot rolling and cold rolling, annealing treatment, surface pretreatment, electrolytic corrosion and post-treatment. Through optimization of the whole process, the problem of few and uneven corrosion pits of the cathode foil is solved, and the corrosion uniformity is improved. Through synergistic optimization of the whole process of the preparation of the aluminum electrolytic capacitor cathode foil, high-purity raw materials are selected, and alloy components are accurately controlled. Through standardized ingot casting, rolling forming, quenching-ageing composite annealing, grading surface pretreatment, electrolytic corrosion with special formula and parameters and post-treatment process, the problem of few and uneven distribution of corrosion pits of the existing cathode foil is solved from the root, the aluminum foil grain is effectively refined, the surface activity and reaction consistency are improved, the prepared cathode foil has high-density and uniform distribution of surface corrosion pits and small diameter deviation, and the use requirement of medium and high-end aluminum electrolytic capacitors is met.

Description

Technical Field

[0001] This invention relates to the field of aluminum electrolytic capacitor electrode material preparation technology, specifically to a method for preparing aluminum electrolytic capacitor cathode foil to improve corrosion uniformity. Background Technology

[0002] Aluminum electrolytic capacitors are widely used in many fields such as home appliances, electronic equipment, and communication equipment due to their advantages such as large capacity, low cost, small size, and convenient use. As the core electrode material of aluminum electrolytic capacitors, the surface corrosion quality of the cathode foil directly determines the key performance indicators of the capacitor, such as specific capacitance, leakage current, and service life. In the cathode foil preparation process, the corrosion process forms uniformly distributed corrosion pits on the surface of the aluminum foil, which can effectively increase the surface area of ​​the aluminum foil and improve the specific capacitance and energy density of the capacitor.

[0003] Currently, the existing manufacturing processes for cathode foils of aluminum electrolytic capacitors generally suffer from a small number of corrosion pits and uneven distribution. The main reasons are the uneven microstructure of the aluminum foil raw materials, imperfect pretreatment processes, and unreasonable corrosion system parameters. These factors lead to inconsistent reaction rates on the aluminum foil surface during corrosion, with some areas experiencing excessive corrosion and forming large-sized pits, while others are under-corroded and have almost no pits. Consequently, the cathode foil surface roughness varies greatly, the specific capacitance is low, and the stability is poor, failing to meet the application requirements of mid-to-high-end aluminum electrolytic capacitors.

[0004] In existing technologies, although some solutions attempt to improve corrosion uniformity by adjusting the corrosion solution formula or corrosion temperature, they do not optimize the entire process of aluminum foil preparation, and fail to solve the problem of few and uneven corrosion pits at the root. In addition, they have drawbacks such as complex processes, high costs, and poor operability.

[0005] Therefore, it is necessary to invent a method for preparing aluminum electrolytic capacitor cathode foil that improves corrosion uniformity to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing aluminum electrolytic capacitor cathode foil that improves corrosion uniformity, so as to solve the problems in the above-mentioned technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity, comprising the following steps: Step 1: Raw material selection and pretreatment: Select high-purity pure aluminum ingots and add a specific proportion of aluminum-manganese master alloy. After melting and holding at a certain temperature, obtain qualified aluminum alloy liquid, remove impurities from the raw materials and stabilize the alloy composition. Step 2, Ingot Preparation: The aluminum alloy liquid is subjected to nitrogen degassing, double ceramic filtration and settling treatment, and a semi-continuous casting process is used to prepare aluminum alloy ingots with uniform composition and no porosity defects. Step 3, Hot Rolling and Cold Rolling: After milling and homogenization of the ingot, it is rolled into aluminum strip by hot rolling, and then subjected to multiple cold rolling passes to control the reduction amount, so as to obtain aluminum foil substrate with standard thickness and uniform structure. Step 4, Annealing: The aluminum foil substrate is treated with a quenching-aging composite process to eliminate cold rolling stress, refine grains, and improve the plasticity and subsequent corrosion performance of the aluminum foil. Step 5, Surface Pretreatment: Through a series of processes including degreasing, alkaline washing, acid washing, and water washing, oil, oxide film, and impurities on the surface of aluminum foil are removed to obtain a clean and highly active surface. Step 6, Electrolytic corrosion: Using a corrosion solution with specific components, the pretreated aluminum foil is corroded by alternating current electrolysis. The corrosion parameters are controlled to form uniformly distributed corrosion pits on the surface of the aluminum foil. Step 7, Post-processing: The etched aluminum foil is rinsed multiple times with deionized water to remove residual corrosion liquid from the surface. After drying and natural cooling, the finished cathode foil is obtained. By optimizing the entire process, the problem of few and uneven corrosion pits on the cathode foil is solved, thus improving the uniformity of corrosion.

[0008] Preferably, in step 1, the raw material is selected as pure aluminum ingot with a purity ≥ 99.99 wt.%, and an aluminum-manganese master alloy is added to control the manganese content in the alloy liquid at 0.1-0.3 wt.%. The mass fraction of manganese in the aluminum-manganese master alloy is 5 wt.%, the mass fraction of impurities is ≤ 0.5 wt.%, and the balance is aluminum. The melting temperature is 740-760℃, and the holding time is 20-30 min.

[0009] Preferably, in step 2, nitrogen is used for degassing of the aluminum alloy liquid, with a nitrogen pressure of 0.1-0.3 MPa, a flow rate of 55-75 L / min, a degassing time of 10-15 min, filtration using a double filtration of 40 ppi + 50 ppi ceramic filter plates, a settling time of 20-25 min, a settling temperature of 710-730℃, a semi-continuous casting speed of 55-70 mm / min, and a casting water temperature ≤40℃.

[0010] Preferably, in step 3, the aluminum alloy ingot is milled to a thickness of 0.3-0.5 mm; the homogenization treatment temperature is 590-610℃, and the holding temperature is 8-12 h; the hot rolling temperature is 480-520℃, and it is rolled into an aluminum strip with a thickness of 2-3 mm; the cold rolling reduction per pass is 15-25%, and it is finally rolled into an aluminum foil substrate with a thickness of 0.01-0.03 mm.

[0011] Preferably, in step 4, the annealing treatment adopts a quenching-aging composite process, specifically: first, the temperature is raised to 620-640℃ and held for 5-7 hours, then rapidly quenched to room temperature at a rate of ≥100℃ / min; then the temperature is raised to 60-80℃ and aged for 10-12 hours.

[0012] Preferably, in step 5, the surface pretreatment includes degreasing, alkaline washing, acid washing, and water washing, wherein: degreasing uses an alkaline degreasing solution at a temperature of 50-60℃ for 5-8 minutes; alkaline washing uses a 5-8 wt.% sodium hydroxide solution at a temperature of 40-50℃ for 1-2 minutes; acid washing uses a 3-5 wt.% dilute nitric acid solution for 30-60 seconds; and each treatment is followed by rinsing with deionized water 2-3 times.

[0013] Preferably, in step 6, the electrolytic corrosion is carried out by alternating current electrolysis, and the corrosion solution is composed of the following components by mass fraction: hydrochloric acid 8-12%, sulfuric acid 3-5%, copper chloride 0.05-0.1%, citric acid 0.1-0.2%, and deionized water balance.

[0014] Preferably, in step 6, the electrolytic corrosion temperature is 35-45℃, the current density is 15-25A / dm², the corrosion time is 8-12min, and the corrosion solution is continuously stirred at a rate of 100-150r / min during the corrosion process.

[0015] Preferably, in step 7, the post-treatment includes rinsing with deionized water 3-4 times, followed by drying at 80-100°C for 10-15 minutes, and naturally cooling to room temperature to obtain the finished cathode foil.

[0016] Preferably, the prepared aluminum electrolytic capacitor cathode foil has a uniformly distributed surface corrosion pits with a corrosion pit density ≥1.2×10⁻⁶. 4 Number of pits per cm², corrosion pit diameter deviation ≤ 0.2 μm, specific capacitance ≥ 550 μF·cm² - ².

[0017] The technical effects and advantages provided by the present invention in the above technical solution are as follows: By synergistically optimizing the entire process of aluminum electrolytic capacitor cathode foil preparation, selecting high-purity raw materials and precisely controlling alloy composition, and employing standardized processes such as ingot casting, rolling, quenching-aging composite annealing, graded surface pretreatment, and electrolytic corrosion with proprietary formulas and parameters, as well as post-treatment, the problem of few and unevenly distributed corrosion pits in existing cathode foils has been fundamentally solved. This effectively refines the aluminum foil grains, improves surface activity and reaction consistency, resulting in a high-density and uniform distribution of corrosion pits on the surface of the prepared cathode foil with small diameter deviations. Key performance indicators such as specific capacitance are excellent, meeting the needs of mid-to-high-end aluminum electrolytic capacitors. Furthermore, the process is simple and controllable, with reasonable production costs and strong industrial mass production capabilities. Attached Figure Description

[0018] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0020] This invention provides, for example Figure 1 The method for preparing an aluminum electrolytic capacitor cathode foil to improve corrosion uniformity includes the following steps: Step 1: Raw material selection and pretreatment: Select high-purity pure aluminum ingots and add a specific proportion of aluminum-manganese master alloy. After melting and holding at a certain temperature, obtain qualified aluminum alloy liquid, remove impurities from the raw materials and stabilize the alloy composition. Step 2, Ingot Preparation: The aluminum alloy liquid is subjected to nitrogen degassing, double ceramic filtration and settling treatment, and a semi-continuous casting process is used to prepare aluminum alloy ingots with uniform composition and no porosity defects. Step 3, Hot Rolling and Cold Rolling: After milling and homogenization of the ingot, it is rolled into aluminum strip by hot rolling, and then subjected to multiple cold rolling passes to control the reduction amount, so as to obtain aluminum foil substrate with standard thickness and uniform structure. Step 4, Annealing: The aluminum foil substrate is treated with a quenching-aging composite process to eliminate cold rolling stress, refine grains, and improve the plasticity and subsequent corrosion performance of the aluminum foil. Step 5, Surface Pretreatment: Through a series of processes including degreasing, alkaline washing, acid washing, and water washing, oil, oxide film, and impurities on the surface of aluminum foil are removed to obtain a clean and highly active surface. Step 6, Electrolytic corrosion: Using a corrosion solution with specific components, the pretreated aluminum foil is corroded by alternating current electrolysis. The corrosion parameters are controlled to form uniformly distributed corrosion pits on the surface of the aluminum foil. Step 7, Post-processing: The etched aluminum foil is rinsed multiple times with deionized water to remove residual corrosion liquid from the surface. After drying and natural cooling, the finished cathode foil is obtained. By optimizing the entire process, the problem of few and uneven corrosion pits on the cathode foil is solved, thus improving the uniformity of corrosion. Specifically, the entire process, from raw material alloy ratio, ingot preparation, rolling and forming, annealing grain control, surface pretreatment to electrolytic corrosion and post-treatment, is synergistically optimized. This breaks through the limitations of existing technologies that only adjust the corrosion liquid or corrosion parameters. It simultaneously controls the aluminum foil matrix composition, microstructure, surface activity, and corrosion reaction environment from multiple dimensions, thoroughly solving the industry pain points of existing cathode foil corrosion pits, such as small number, uneven distribution, and local over- or under-corrosion. High-purity pure aluminum ingots are combined with a specific ratio of aluminum-manganese master alloy, and the manganese content is precisely controlled. Combined with nitrogen degassing, double ceramic filtration, and static treatment, impurities in the melt are effectively removed and porosity defects are eliminated, producing aluminum alloy ingots with uniform composition and dense microstructure. Then, through precise milling, homogenization heat treatment, and standardized hot rolling and cold rolling processes, the reduction and finished product thickness are strictly controlled, so that the internal grain arrangement of the aluminum foil substrate is uniform and the microstructure is consistent, laying a good matrix foundation for subsequent uniform electrolytic corrosion.

[0021] The raw material selected is pure aluminum ingot with a purity ≥99.99wt.%. An aluminum-manganese master alloy is added to control the manganese content in the alloy liquid at 0.1-0.3wt.%, with a manganese mass fraction of 5wt.% and an impurity mass fraction ≤0.5wt.%, the balance being aluminum. The melting temperature is 740-760℃, and the holding time is 20-30min. In step 2, nitrogen is used for degassing of the aluminum alloy liquid at a pressure of 0.1-0.3MPa, a flow rate of 55-75L / min, and a degassing time of 10-15min. Filtration is performed using a double filtration system with 40ppi + 50ppi ceramic filter plates. The settling time is 20-25 minutes, the settling temperature is 710-730℃, the semi-continuous casting speed is 55-70 mm / min, and the casting water temperature is ≤40℃. In step 3, the aluminum alloy ingot is milled to a thickness of 0.3-0.5 mm, the homogenization treatment temperature is 590-610℃, the holding time is 8-12 hours, the hot rolling temperature is 480-520℃, and it is rolled into an aluminum strip with a thickness of 2-3 mm. The cold rolling reduction per pass is 15-25%, and finally, it is rolled into an aluminum foil substrate with a thickness of 0.01-0.03 mm. The annealing treatment adopts a quenching-aging composite process, specifically: first, the temperature is raised to 620-640℃, and the holding time is 5- After 7 hours, the surface is rapidly quenched to room temperature at a rate of ≥100℃ / min, then heated to 60-80℃ and aged for 10-12 hours. Surface pretreatment includes degreasing, alkaline washing, acid washing, and water washing. Specifically: degreasing uses an alkaline degreasing solution at 50-60℃ for 5-8 minutes; alkaline washing uses a 5-8 wt.% sodium hydroxide solution at 40-50℃ for 1-2 minutes; and acid washing uses a 3-5 wt.% dilute nitric acid solution for 30-60 seconds. After each treatment, the surface is rinsed 2-3 times with deionized water. Electrolytic corrosion uses AC electrolysis. The corrosion solution consists of the following components by mass fraction: The electrolytic corrosion process involves the following components: hydrochloric acid 8-12%, sulfuric acid 3-5%, copper chloride 0.05-0.1%, citric acid 0.1-0.2%, and deionized water as the balance. The electrolytic corrosion temperature is 35-45℃, the current density is 15-25 A / dm², and the corrosion time is 8-12 min. During corrosion, the corrosion solution is continuously stirred at a rate of 100-150 r / min. Post-treatment includes rinsing with deionized water 3-4 times, followed by drying at 80-100℃ for 10-15 min, and natural cooling to room temperature to obtain the finished cathode foil. The prepared aluminum electrolytic capacitor cathode foil has a uniformly distributed surface corrosion pit density ≥1.2 × 10⁻⁶. 4 Number of pits per cm², corrosion pit diameter deviation ≤ 0.2 μm, specific capacitance ≥ 550 μF·cm² - ².

[0022] Specifically, a proprietary quenching-aging composite annealing process is employed to effectively eliminate internal stress generated during cold rolling, while simultaneously refining grain size. This significantly enhances the plasticity and surface reactivity of the aluminum foil substrate, ensuring a more uniform electrochemical reaction rate during electrolytic corrosion. This avoids uneven corrosion caused by stress concentration in the substrate and grain differences. Through a continuous, standardized process of degreasing, alkaline washing, acid washing, and multi-stage deionized water rinsing, oil, natural oxide film, and adhering impurities on the aluminum foil surface are thoroughly removed, resulting in a highly clean aluminum foil surface with uniform surface activity. This prevents surface contaminants from interfering with the corrosion reaction and ensures optimal corrosion resistance. The nucleation sites of the corrosion pits are evenly distributed. A specific composite etching solution of hydrochloric acid, sulfuric acid, copper chloride, and citric acid is prepared, and with limited etching temperature, current density, etching time, and stirring rate, the corrosion pits can be stably induced to form uniformly on the aluminum foil surface under AC electrolysis mode. This effectively inhibits the formation of large-sized corrosion pits, reduces the diameter deviation of corrosion pits, and achieves a high-density and uniform arrangement of corrosion pits. The cathode foil prepared by this method has a high density of corrosion pits, small diameter deviation, excellent surface consistency, and outstanding specific capacitance performance. It significantly reduces the surface roughness difference of the cathode foil, reduces capacitor leakage current, and improves capacitance stability and long-term service life.

[0023] Working principle of this invention: Refer to the instruction manual appendix Figure 1When using this invention, the core problem of few and unevenly distributed corrosion pits on the cathode foil of aluminum electrolytic capacitors is first solved through synergistic optimization of the entire process. This ultimately yields a cathode foil product with uniform surface corrosion and excellent electrical performance. Its working principle revolves around four core elements: "composition homogenization, microstructure refinement, surface activation, and controllable corrosion." The principles of each step are interconnected and work synergistically. Selecting high-purity aluminum ingots with a purity ≥99.99wt.% reduces the interference of impurities on the subsequent corrosion process (impurities easily form corrosion blind zones or accelerate localized corrosion, leading to uneven corrosion). Adding a specific proportion of aluminum-manganese master alloy (controlling the manganese content to 0.1-0.3wt.%) utilizes the solid solution strengthening effect of manganese in the aluminum alloy to refine the alloy grains and improve the electrochemical stability of the aluminum alloy, laying the compositional foundation for subsequent uniform corrosion. Melting at 740-760℃ and holding for 20-30 minutes ensures full fusion of the aluminum ingot and master alloy, removes gases and impurities from the raw materials, stabilizes the alloy composition, and avoids poor corrosion caused by component segregation. To address this issue, nitrogen degassing of the molten aluminum alloy (0.1-0.3 MPa pressure, 55-75 L / min flow rate) effectively removes gases such as hydrogen from the melt, preventing porosity defects in the ingot (porosity leads to uneven current distribution during corrosion, creating localized non-corrosion areas). A 40ppi + 50ppi dual ceramic filter further filters out oxide inclusions in the melt. Static treatment (710-730℃, 20-25 min) homogenizes the melt composition, reducing localized compositional fluctuations. This process is suitable for semi-continuous casting. The casting process (55-70 mm / min speed, ≤40℃ casting water temperature) can obtain a dense, non-porous, and uniformly composed ingot. Subsequent milling removes the surface defect layer of the ingot, and homogenization treatment (590-610℃, 8-12h) eliminates internal stress and refines grains. Hot rolling (480-520℃) and multi-pass cold rolling (15-25% reduction per pass) work together to ensure that the aluminum foil substrate thickness meets the standard (0.01-0.03mm) and has a uniform structure, avoiding corrosion rate differences caused by uneven structure. The quenching-aging composite annealing process (first holding at 620-640℃ for 5-7 hours, quenching at a rate of ≥100℃ / min to room temperature, then aging at 60-80℃ for 10-12 hours) can effectively eliminate internal stress generated during cold rolling, refine aluminum foil grains, improve aluminum foil plasticity, and optimize the electrochemical activity of the aluminum foil surface, making the current distribution more uniform during subsequent corrosion. The surface pretreatment involves a series of degreasing, alkaline washing, acid washing, and water washing processes to sequentially remove oil stains (affecting the contact of the etchant), oxide film (inhibiting the corrosion reaction), and residual impurities from the aluminum foil surface, obtaining a clean and highly active surface. This ensures full and uniform contact between the etchant and the aluminum foil surface, avoiding uneven corrosion caused by poor local contact. A specific composition etchant is used (8-12% hydrochloric acid, 3-5% sulfuric acid, 0.05-0.1% copper chloride, and 0.1-0.2% citric acid). Hydrochloric acid and sulfuric acid serve as the main etchants to achieve uniform dissolution of the aluminum foil surface. Copper chloride acts as a corrosion catalyst, promoting the nucleation and growth of corrosion pits and preventing them from becoming too large or sparsely distributed. Citric acid adjusts the pH of the etching solution, inhibiting excessive local corrosion and refining the size of the corrosion pits. Alternating current electrolysis (35-45℃, 15-25A / dm², 8-12min) combined with stirring at 100-150r / min ensures uniform concentration and temperature distribution of the etching solution, guaranteeing consistent corrosion rates across the aluminum foil surface and forming uniformly distributed corrosion pits. Post-treatment involves 3-4 rinses with deionized water to remove residual etching solution (to prevent continued corrosion from residual etchants leading to pit diameter deviations). Drying at 80-100℃ for 10-15min followed by natural cooling ensures the finished product surface is dry and free of impurities, ultimately achieving a corrosion pit density ≥1.2×10⁻⁶. 4 Number of pieces / cm², pit diameter deviation ≤0.2μm, specific capacitance ≥550μF·cm² - ² High-quality cathode foil.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing cathode foil for aluminum electrolytic capacitors to improve corrosion uniformity, characterized in that, Includes the following steps: Step 1: Raw material selection and pretreatment: Select high-purity pure aluminum ingots and add a specific proportion of aluminum-manganese master alloy. After melting and holding at a certain temperature, obtain qualified aluminum alloy liquid, remove impurities from the raw materials and stabilize the alloy composition. Step 2, Ingot Preparation: The aluminum alloy liquid is subjected to nitrogen degassing, double ceramic filtration and settling treatment, and a semi-continuous casting process is used to prepare aluminum alloy ingots with uniform composition and no porosity defects. Step 3, Hot Rolling and Cold Rolling: After milling and homogenization of the ingot, it is rolled into aluminum strip by hot rolling, and then subjected to multiple cold rolling passes to control the reduction amount, so as to obtain aluminum foil substrate with standard thickness and uniform structure. Step 4, Annealing: The aluminum foil substrate is treated with a quenching-aging composite process to eliminate cold rolling stress, refine grains, and improve the plasticity and subsequent corrosion performance of the aluminum foil. Step 5, Surface Pretreatment: Through a series of processes including degreasing, alkaline washing, acid washing, and water washing, oil, oxide film, and impurities on the surface of aluminum foil are removed to obtain a clean and highly active surface. Step 6, Electrolytic corrosion: Using a corrosion solution with specific components, the pretreated aluminum foil is corroded by alternating current electrolysis. The corrosion parameters are controlled to form uniformly distributed corrosion pits on the surface of the aluminum foil. Step 7, Post-processing: The etched aluminum foil is rinsed multiple times with deionized water to remove residual corrosion liquid from the surface. After drying and natural cooling, the finished cathode foil is obtained. By optimizing the entire process, the problem of few and uneven corrosion pits on the cathode foil is solved, thus improving the uniformity of corrosion.

2. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 1, pure aluminum ingots with a purity of ≥99.99wt.% are selected as raw materials. An aluminum-manganese master alloy is added to control the manganese content in the alloy liquid at 0.1-0.3wt.%. The mass fraction of manganese in the aluminum-manganese master alloy is 5wt.%, the mass fraction of impurities is ≤0.5wt.%, and the balance is aluminum. The melting temperature is 740-760℃ and the holding time is 20-30min.

3. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 2, nitrogen is used for degassing of the aluminum alloy liquid. The nitrogen pressure is 0.1-0.3MPa, the flow rate is 55-75L / min, and the degassing time is 10-15min. The filtration is carried out using a double filtration of 40ppi + 50ppi ceramic filter plates. The settling time is 20-25min, the settling temperature is 710-730℃, the semi-continuous casting speed is 55-70mm / min, and the casting water temperature is ≤40℃.

4. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 3, the aluminum alloy ingot is milled to a thickness of 0.3-0.5 mm; the homogenization treatment temperature is 590-610℃ and the holding temperature is 8-12 h; the hot rolling temperature is 480-520℃ and it is rolled into an aluminum strip with a thickness of 2-3 mm; the cold rolling reduction is 15-25% per pass and it is finally rolled into an aluminum foil substrate with a thickness of 0.01-0.03 mm.

5. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 4, the annealing treatment adopts a quenching-aging composite process, specifically: first, the temperature is raised to 620-640℃ and held for 5-7 hours, then rapidly quenched to room temperature at a rate of ≥100℃ / min; then the temperature is raised to 60-80℃ and aged for 10-12 hours.

6. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 5, the surface pretreatment includes degreasing, alkaline washing, acid washing, and water washing. Specifically, degreasing is performed using an alkaline degreasing solution at a temperature of 50-60℃ for 5-8 minutes; alkaline washing is performed using a 5-8 wt.% sodium hydroxide solution at a temperature of 40-50℃ for 1-2 minutes; acid washing is performed using a 3-5 wt.% dilute nitric acid solution for 30-60 seconds; and each treatment is followed by rinsing with deionized water 2-3 times.

7. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 6, the electrolytic corrosion is carried out by alternating current electrolysis. The corrosion solution is composed of the following components by mass fraction: hydrochloric acid 8-12%, sulfuric acid 3-5%, copper chloride 0.05-0.1%, citric acid 0.1-0.2%, and deionized water balance.

8. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 6, the electrolytic corrosion temperature is 35-45℃, the current density is 15-25A / dm², the corrosion time is 8-12min, and the corrosion solution is continuously stirred at a rate of 100-150r / min during the corrosion process.

9. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: In step 7, the post-treatment includes rinsing with deionized water 3-4 times, followed by drying at 80-100℃ for 10-15 minutes, and naturally cooling to room temperature to obtain the finished cathode foil.

10. The method for preparing aluminum electrolytic capacitor cathode foil with improved corrosion uniformity according to claim 1, characterized in that: The prepared aluminum electrolytic capacitor cathode foil has a uniformly distributed surface corrosion pit, with a corrosion pit density ≥1.2×10⁻⁶. 4 Number of pits per cm², corrosion pit diameter deviation ≤ 0.2 μm, specific capacitance ≥ 550 μF·cm² - ².

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