Preparation method of electrode foil, electrode foil and aluminum electrolytic capacitor

Abstract

The invention belongs to the technical field of electrode foil formation treatment, and particularly relates to a preparation method of an electrode foil, the electrode foil and an aluminum electrolytic capacitor. The preparation method comprises the following steps: carrying out first-stage formation, second-stage formation, repair treatment and third-stage formation on an aluminum foil; the first-stage formation and the third-stage formation are independently carried out in a treatment solution containing a boron element; the secondary formation is carried out in a treatment solution containing a phosphorus element; the repairing treatment is carried out in treating fluid containing rare earth ions. According to the preparation method of the electrode foil, the phosphorus-containing active substances and the rare earth ions are introduced into the formation process, the effects of reducing energy consumption and improving the specific volume and the CV product of the electrode foil are achieved, and meanwhile the leakage current of the electrode foil is reduced.

Description

Technical Field

[0001] This invention belongs to the field of electrode foil formation technology, specifically relating to a method for preparing electrode foil, and an electrode foil and an aluminum electrolytic capacitor. Background Technology

[0002] Currently, the research and development of anode materials for aluminum electrolytic capacitors generally faces the following technical problems: High specific capacitance electrode foils are mostly prepared using dielectric layer thinning or surface etching expansion techniques. Although this can significantly improve the specific capacitance value, it will simultaneously reduce the mechanical strength, density, and crystal orientation of the oxide film, leading to a decrease in dielectric layer breakdown voltage and seriously affecting the reliability of capacitor operation. In addition, existing technical routes excessively pursue the improvement of the single indicator of specific capacitance value, while neglecting the matching optimization of withstand voltage performance, making it difficult to improve the CV product (i.e., the product of specific capacitance and withstand voltage value). At the same time, the significant increase in formation energy consumption leads to high production costs. More seriously, the heterogeneity of surface microstructure caused by conventional expansion processes will increase the leakage current of the anode foil by 2-3 orders of magnitude under high temperature load conditions, which greatly restricts the application of capacitors in high-voltage scenarios such as new energy and electric vehicles.

[0003] In summary, existing processes suffer from numerous significant problems, such as high formation energy consumption, difficulty in improving specific capacity and CV product, and high leakage current of the prepared electrode foil. There is an urgent need for a preparation method that can reduce the leakage current of the electrode foil while improving its specific capacity and CV product without increasing formation energy consumption. Summary of the Invention

[0004] The present invention aims to provide a method for preparing electrode foil, an electrode foil and an aluminum electrolytic capacitor. The method for preparing electrode foil provided by the present invention introduces phosphorus and rare earth ions into the formation process, thereby reducing energy consumption, increasing the specific capacitance and CV product of the electrode foil, and reducing the leakage current of the electrode foil.

[0005] In a first aspect, the present invention provides a method for preparing an electrode foil, the method comprising: performing primary formation, secondary formation, repair treatment and tertiary formation on an aluminum foil; The primary and tertiary formations are each carried out independently in a treatment solution containing boron. The secondary formation is carried out in a treatment solution containing phosphorus. The repair treatment is carried out in a treatment solution containing rare earth ions.

[0006] According to some embodiments of the present invention, the method for preparing the electrode foil provided by the present invention may further include the following auxiliary technical features: In some embodiments, the primary formation processing solution is a processing solution containing boron.

[0007] In some embodiments, the primary formation treatment solution includes at least one of boric acid and ammonium pentaborate.

[0008] In some embodiments, the primary formation treatment solution is a mixed aqueous solution of boric acid and ammonium pentaborate.

[0009] In some embodiments, the boric acid content in the primary formation treatment solution is 3%-8% by mass. Specifically, the boric acid content in the primary formation treatment solution is any value within the range of 3%, 4%, 5%, 6%, 7%, 8%, or 3%-8%.

[0010] In some embodiments, the mass percentage of ammonium pentaborate in the primary formation treatment solution is 0.2%-0.8%. Specifically, the mass percentage of ammonium pentaborate in the primary formation treatment solution is any value within the range of 0.2%, 0.4%, 0.6%, 0.8%, or 0.2%-0.8%.

[0011] In some embodiments, the formation voltage of the first-stage formation is 60V-110V. Specifically, the formation voltage of the first-stage formation is any value within the range of 60V, 70V, 80V, 90V, 100V, 110V, or 60V-110V.

[0012] In some embodiments, the primary formation temperature is 70°C-90°C. Specifically, the primary formation temperature is any value within the range of 70°C, 75°C, 80°C, 85°C, 90°C, or 70°C-90°C.

[0013] In some implementations, the first-stage formation time is 90 s-300 s. Specifically, the first-stage formation time is any value within the range of 90 s, 100 s, 110 s, 120 s, 130 s, 140 s, 150 s, 160 s, 170 s, 180 s, 190 s, 200 s, 210 s, 220 s, 230 s, 240 s, 250 s, 260 s, 270 s, 280 s, 290 s, 300 s, or 90 s-300 s.

[0014] In some embodiments, the current density of the first-stage formation is 5 mA / cm². 2 -15 mA / cm 2 Specifically, the current density of the first-stage formation is 5 mA / cm². 2 6 mA / cm 2 7 mA / cm 2 8 mA / cm 2 9 mA / cm 2 10 mA / cm2 11mA / cm 2 12 mA / cm 2 13 mA / cm 2 14 mA / cm 2 15 mA / cm 2 or 5 mA / cm 2 -15 mA / cm 2 Any value within the range.

[0015] In some embodiments, the secondary formation processing solution is a processing solution that includes phosphorus.

[0016] In some embodiments, the secondary formation treatment solution includes NH4H2PO4, NaH2PO4, (NH4)2HPO4, Na2HPO4, and Na5P3O. 10 At least one of (NaPO3)6, hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, and ethylenediaminetetramethylene phosphonic acid.

[0017] In some embodiments, the secondary formation treatment solution is NH4H2PO4, NaH2PO4, (NH4)2HPO4, Na2HPO4, or Na5P3O. 10 An aqueous solution of at least one of (NaPO3)6, hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, and ethylenediaminetetramethylenephosphonic acid.

[0018] In some embodiments, the mass percentage of solute in the secondary formation treatment solution is 0.1%-0.8%. Specifically, the mass percentage of solute in the secondary formation treatment solution is any value within the range of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.1%-0.8%.

[0019] In some embodiments, the formation voltage of the secondary formation is 120V-220V. Specifically, the formation voltage of the secondary formation is any value within the range of 120V, 130V, 140V, 150V, 160V, 170V, 180V, 190V, 200V, 210V, 220V, or 120V-220V.

[0020] In some embodiments, the secondary formation temperature is 70°C-90°C. Specifically, the secondary formation temperature is any value within the range of 70°C, 75°C, 80°C, 85°C, 90°C, or 70°C-90°C.

[0021] In some implementations, the secondary formation time is 200 s-400 s. Specifically, the secondary formation time is any value within the range of 200 s, 250 s, 300 s, 350 s, 400 s, or 200 s-400 s.

[0022] In some embodiments, the current density of the secondary formation is 10 mA / cm². 2 -25 mA / cm 2 Specifically, the current density of the secondary formation is 10 mA / cm². 2 15 mA / cm 2 20 mA / cm 2 25 mA / cm 2 or 10 mA / cm 2 -25 mA / cm 2 Any value within the range.

[0023] In some embodiments, the treatment solution for the repair treatment is a treatment solution containing rare earth ions.

[0024] In some embodiments, the treatment solution for the repair process includes at least one of cerium nitrate and lanthanum nitrate.

[0025] In some embodiments, the treatment solution for the remediation process is an aqueous solution of lanthanum nitrate and / or cerium nitrate.

[0026] In some embodiments, the mass percentage of lanthanum nitrate and / or cerium nitrate in the treatment solution of the remediation treatment is 0.2%-4%. Specifically, the mass percentage of lanthanum nitrate and / or cerium nitrate in the treatment solution of the remediation treatment is any value within the range of 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 0.2%-4%.

[0027] In some embodiments, the temperature of the repair treatment is 30°C-85°C. Specifically, the temperature of the repair treatment is any value within the range of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 30°C-85°C.

[0028] In some implementations, the repair process takes 2 to 10 minutes. Specifically, the repair process takes 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any value within the range of 2 to 10 minutes.

[0029] In some embodiments, the preparation method further includes pre-treating the aluminum foil by boiling it in water before primary formation.

[0030] In some embodiments, the boiling pretreatment includes placing the aluminum foil in boiling water for 5 min to 20 min. Specifically, the boiling pretreatment includes placing the aluminum foil in boiling water for any value within the range of 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, or 5 min to 20 min.

[0031] In some embodiments, the preparation method includes performing a quaternary formation after a tertiary formation.

[0032] In some embodiments, the quaternary formation is carried out in a treatment solution containing boron.

[0033] In some embodiments, the treatment solutions for the tertiary and quaternary formations are each independently treatment solutions containing boron.

[0034] In some embodiments, the treatment solutions for the tertiary and quaternary formations each independently include boric acid and citric acid.

[0035] In some embodiments, the treatment solutions for the tertiary and quaternary formations are each independently a mixed aqueous solution of boric acid and citric acid.

[0036] In some embodiments, the mass percentage of boric acid in the treatment solutions of the tertiary and quaternary formations is independently 2%-10%. Specifically, the mass percentage of boric acid in the treatment solutions of the tertiary and quaternary formations is independently 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value within the range of 2%-10%.

[0037] In some embodiments, the mass percentage of citric acid in the treatment solutions of the tertiary and quaternary formations is independently 0.2%-2%. Specifically, the mass percentage of citric acid in the treatment solutions of the tertiary and quaternary formations is independently any value within the range of 0.2%, 0.5%, 1%, 1.5%, 2%, or 0.2%-2%.

[0038] In some embodiments, the formation voltage of the three-stage formation is 420V-500V. Specifically, the formation voltage of the three-stage formation is any value within the range of 420V, 430V, 440V, 450V, 460V, 470V, 480V, 490V, 500V, or 420V-500V.

[0039] In some embodiments, the tertiary formation temperature is 70°C-90°C. Specifically, the tertiary formation temperature is any value within the range of 70°C, 75°C, 80°C, 85°C, 90°C, or 70°C-90°C.

[0040] In some implementations, the time for the three-stage formation is 550s-650s. Specifically, the time for the three-stage formation is any value within the range of 550s, 560s, 570s, 580s, 590s, 600s, 610s, 620s, 630s, 640s, 650s, or 550s-650s.

[0041] In some embodiments, the current density of the three-stage formation is 15 mA / cm². 2 -25 mA / cm 2 Specifically, the current density of the three-stage formation is 15 mA / cm². 2 16 mA / cm 2 17 mA / cm 2 18 mA / cm 2 19 mA / cm 2 20 mA / cm 2 21 mA / cm 2 22 mA / cm 2 23 mA / cm 2 24 mA / cm 2 25 mA / cm 2 Or 15 mA / cm 2 -25 mA / cm 2 Any value within the range.

[0042] In some embodiments, the formation voltage of the four-stage formation is 520V-600V. Specifically, the formation voltage of the four-stage formation is any value within the range of 520V, 530V, 540V, 550V, 560V, 570V, 580V, 590V, 600V, or 520V-600V.

[0043] In some embodiments, the temperature of the fourth-stage formation is 70°C-90°C. Specifically, the temperature of the fourth-stage formation is any value within the range of 70°C, 75°C, 80°C, 85°C, 90°C, or 70°C-90°C.

[0044] In some implementations, the fourth-level formation time is 900s-1200s. Specifically, the fourth-level formation time is any value within the range of 900s, 950s, 1000s, 1050s, 1100s, 1150s, 1200s, or 900s-1200s.

[0045] In some embodiments, the current density of the quaternary formation is 15 mA / cm². 2 -25 mA / cm 2 Specifically, the current density of the fourth-stage formation is 15 mA / cm². 2 16 mA / cm 2 17 mA / cm 2 18 mA / cm 2 19 mA / cm 2 20 mA / cm 2 21 mA / cm 2 22 mA / cm 2 23 mA / cm 2 24 mA / cm 2 25 mA / cm 2 Or 15 mA / cm 2 -25 mA / cm 2 Or 15mA / cm 2 -25 mA / cm 2 Any value within the range.

[0046] In some embodiments, the preparation method further includes depolarization treatment, heat treatment, remodeling treatment, and stabilization treatment.

[0047] In some implementations, the depolarization process includes a first depolarization process and a second depolarization process.

[0048] In some embodiments, the heat treatment includes a first heat treatment and a second heat treatment.

[0049] In some embodiments, the repair forming process includes a first repair forming process, a second repair forming process, and a third repair forming process.

[0050] In some embodiments, the depolarization treatment is carried out in an aqueous phosphoric acid solution.

[0051] In some embodiments, the first depolarization treatment is carried out in an aqueous phosphoric acid solution.

[0052] In some embodiments, the treatment solution for the first depolarization treatment is an aqueous solution of phosphoric acid.

[0053] In some embodiments, the mass percentage of phosphoric acid in the treatment solution of the first depolarization treatment is 4%-6%. Specifically, the mass percentage of phosphoric acid in the treatment solution of the first depolarization treatment is any value within the range of 4%, 4.5%, 5%, 5.5%, 6%, or 4%-6%.

[0054] In some embodiments, the temperature of the first depolarization treatment is 40°C-60°C. Specifically, the temperature of the first depolarization treatment is any value within the range of 40°C, 45°C, 50°C, 55°C, 60°C, or 40°C-60°C.

[0055] In some implementations, the duration of the first depolarization process is 120 s to 240 s. Specifically, the duration of the first depolarization process is any value within the range of 120 s, 150 s, 180 s, 210 s, 240 s, or 120 s to 240 s.

[0056] In some embodiments, the second depolarization treatment is carried out in an aqueous phosphoric acid solution.

[0057] In some embodiments, the treatment solution for the second depolarization treatment is an aqueous phosphoric acid solution.

[0058] In some embodiments, the mass percentage of phosphoric acid in the treatment solution of the second depolarization treatment is 6%-8%. Specifically, the mass percentage of phosphoric acid in the treatment solution of the second depolarization treatment is any value within the range of 6%, 6.5%, 7%, 7.5%, 8%, or 6%-8%.

[0059] In some embodiments, the temperature of the second depolarization treatment is 60°C-70°C. Specifically, the temperature of the second depolarization treatment is any value within the range of 60°C, 65°C, 70°C, or 60°C-70°C.

[0060] In some implementations, the duration of the second depolarization process is 120 s to 600 s. Specifically, the duration of the second depolarization process is any value within the range of 120 s, 150 s, 200 s, 250 s, 300 s, 350 s, 400 s, 450 s, 500 s, 550 s, 600 s, or 120 s to 600 s.

[0061] In some embodiments, the temperatures of the first heat treatment and the second heat treatment are each independently between 500°C and 600°C. Specifically, the temperatures of the first heat treatment and the second heat treatment are each independently any value within the range of 500°C, 520°C, 540°C, 560°C, 580°C, 600°C, or 500°C-600°C.

[0062] In some embodiments, the duration of the first heat treatment and the second heat treatment is independently between 100s and 240s. Specifically, the duration of the first heat treatment and the second heat treatment is independently any value within the range of 100s, 120s, 140s, 160s, 180s, 200s, 220s, 240s, or 100s-240s.

[0063] In some embodiments, the first, second, and third formation processes are each carried out independently in an aqueous boric acid solution.

[0064] In some embodiments, the treatment solutions for the first, second, and third re-forming treatments are each independently an aqueous solution of boric acid.

[0065] In some embodiments, the mass percentage of boric acid in the treatment solutions of the first, second, and third replenishment treatments is independently 2%-10%. Specifically, the mass percentage of boric acid in the treatment solutions of the first, second, and third replenishment treatments is independently 2%, 4%, 6%, 8%, 10%, or any value within the range of 2%-10%.

[0066] In some implementations, the re-forming voltages for the first, second, and third re-forming processes are each independently between 570V and 590V. Specifically, the re-forming voltages for the first, second, and third re-forming processes are each independently any value within the range of 570V, 575V, 580V, 585V, 590V, or 570V-590V.

[0067] In some implementations, the time for the first, second, and third supplementary forming processes is independently 400s-500s. Specifically, the time for each of the first, second, and third supplementary forming processes is independently any value within the range of 400s, 420s, 440s, 460s, 480s, 500s, or 400s-500s.

[0068] In some embodiments, the temperatures of the first, second, and third re-forming processes are each independently between 70°C and 90°C. Specifically, the temperatures of the first, second, and third re-forming processes are each independently 70°C, 75°C, 80°C, 85°C, 90°C, or any value within the range of 70°C to 90°C.

[0069] In some embodiments, the current density of the first, second, and third re-forming processes is each independently 15 mA / cm². 2 -25 mA / cm 2 Specifically, the current density for each of the first, second, and third re-forming processes is independently 15 mA / cm². 2 -25 mA / cm 2 Specifically, the current density for each of the first, second, and third re-forming processes is independently 15 mA / cm². 2 16 mA / cm 2 17 mA / cm 2 18 mA / cm 2 19 mA / cm 2 20 mA / cm 2 21 mA / cm 2 22 mA / cm 2 23mA / cm 2 24 mA / cm 2 25 mA / cm 2 Or 15 mA / cm 2 -25 mA / cm 2 Or 15 mA / cm 2 -25 mA / cm 2 Any value within the range.

[0070] In some embodiments, the stabilization treatment is carried out in an aqueous solution of ammonium dihydrogen phosphate.

[0071] In some embodiments, the mass percentage of ammonium dihydrogen phosphate in the stabilization treatment solution is 0.5%-3%. Specifically, the mass percentage of ammonium dihydrogen phosphate in the stabilization treatment solution is any value within the range of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or 0.5%-3%.

[0072] In some embodiments, the stabilization treatment temperature is 50°C-70°C. Specifically, the stabilization treatment temperature is any value within the range of 50°C, 55°C, 60°C, 65°C, 70°C, or 50°C-70°C.

[0073] In some embodiments, the stabilization treatment time is 60s-240s. Specifically, the stabilization treatment time is any value within the range of 60s, 80s, 100s, 120s, 140s, 160s, 180s, 200s, 220s, 240s, or 60s-240s.

[0074] In some embodiments, the preparation method further includes washing with water before any of the treatments. In this invention, any of the treatments includes water boiling pretreatment, primary formation, secondary formation, repair treatment, tertiary formation, quaternary formation, first depolarization treatment, first heat treatment, first repair formation treatment, second depolarization treatment, second repair formation treatment, second heat treatment, third repair formation treatment, stabilization treatment, and drying treatment.

[0075] In some embodiments, the preparation method further includes washing with water after treatment with anhydride and then drying.

[0076] In some embodiments, the drying temperature is 220°C-280°C. Specifically, the drying temperature is any value within the range of 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, or 220°C-280°C.

[0077] In some embodiments, the drying time is 150 s-240 s. Specifically, the drying time is any value within the range of 150 s, 160 s, 170 s, 180 s, 190 s, 200 s, 210 s, 220 s, 230 s, 240 s, or 150 s-240 s.

[0078] In some embodiments, the aluminum foil is an etched foil.

[0079] In a second aspect, the present invention provides an electrode foil, which is prepared by the preparation method described in the first aspect.

[0080] Thirdly, the present invention provides an aluminum electrolytic capacitor, the aluminum electrolytic capacitor comprising an electrode foil prepared by the preparation method described in the first aspect or the electrode foil described in the second aspect.

[0081] The beneficial effects of this invention are as follows: The preparation method provided by this invention, in the early stage of rapid film formation of low-voltage oxide films (primary and secondary formation stages), introduces phosphorus element for secondary formation (including a phosphorus element treatment solution) in addition to the traditional formation solution (including a boron element treatment solution) as the primary formation solution, thereby optimizing the nucleation and growth kinetics of the early oxide film. On the one hand, the low-concentration phosphorus element treatment solution improves the uniformity of film formation; on the other hand, this system affects the structure and defect state of the initial oxide layer, thereby changing its electrical breakdown behavior and effectively suppressing film defects caused by partial discharge or breakdown in the secondary and subsequent formation stages, laying a good foundation for the formation of oxide films with higher crystallinity and more stable structure.

[0082] The preparation method provided by this invention promotes the formation of crystalline Al2O3 film by low-voltage anodic oxidation (secondary formation) in a phosphorus-containing treatment solution, while also thinning the outermost amorphous alumina (formed by boiling in water under heating conditions). In addition, the composite oxide film formed by the incorporation of trace amounts of phosphorus has a higher dielectric constant than a single alumina film, thus further improving the specific capacitance and CV product of the obtained electrode foil.

[0083] The preparation method provided by the present invention uses a traditional forming solution (including a boron-containing treatment solution) for primary forming, followed by secondary forming in a phosphorus-containing treatment solution. Due to the interaction between boron and phosphorus, boron can suppress the incorporation of phosphorus, avoiding local electric field distortion caused by deep phosphorus doping and reducing energy loss in subsequent processes.

[0084] In the preparation method provided by this invention, rare earth ions (Ce) 3+ and / or La 3+ Phosphorus can fill the lattice gaps or oxygen vacancies in the alumina film caused by phosphorus doping, forming a "defect plugging" effect. This reduces the migration channels of ions in the treatment solution through the defects, thus lowering the risk of leakage current in the film. In addition, rare earth ions react with hydroxyl groups (-OH) on the film surface to generate hydroxides such as Ce(OH)3 or La(OH)3. These hydroxides are further dehydrated to form CeO2 and La2O3 nanoparticles, which are uniformly embedded in the phosphorus-doped alumina film. This is equivalent to forming "structural support points" inside the film, improving the mechanical strength and crack resistance of the film, and reducing the leakage current of the electrode foil.

[0085] Terminology Explanation In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0086] The terms “comprising” or “including” are open-ended expressions, meaning they include the contents specified in this application but do not exclude other contents.

[0087] The terms “room temperature” or “normal temperature” refer to ambient temperature, which is approximately 10°C to approximately 35°C, approximately 10°C to approximately 30°C, or approximately 20°C to 30°C, or approximately 25°C.

[0088] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0089] The term "mass percentage" or "mass percentage" indicates the percentage of a certain component in the total mass of a substance. The mass percentage (or mass percentage) of a certain component in the total mass of a substance (%) = (mass of the certain component / mass of the total mass of the substance) × 100%.

[0090] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0092] In the following content, all figures disclosed herein, whether or not they use the words "approximately" or "about," are approximate values. The value of each figure may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a figure with a value of N is disclosed, any figure with a value of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, N+ / -10%, N+ / -15%, or N+ / -20% will be explicitly disclosed, where "+ / -" indicates addition or subtraction.

[0093] Specific Implementation Scheme The following description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0094] The preparation method of the electrode foil of the present invention includes the following steps: pretreatment of corrosion foil by boiling in water - primary formation - secondary formation - repair treatment - tertiary formation - quaternary formation - first depolarization treatment - first heat treatment - first repair formation treatment - second depolarization treatment - second repair formation treatment - second heat treatment - third repair formation treatment - stabilization treatment - drying treatment.

[0095] The method for preparing the electrode foil described in this invention can be specifically explained as including the following steps: S1 Water Boiling Pretreatment: After cleaning with deionized water, the etched foil is placed in boiling water for 5 min-20 min.

[0096] S2 Primary Formation: After the pre-treated etched foil is cleaned with deionized water, it is placed in the primary formation solution (a mixed aqueous solution of boric acid and ammonium pentaborate, where the mass percentage of boric acid is 3%-8% and the mass percentage of ammonium pentaborate is 0.2%-0.8%) for primary formation. The formation voltage is 60V-110V, the formation time is 90s-300s, the formation temperature is 70℃-90℃, and the formation current density is 5mA / cm². 2 -15 mA / cm 2 .

[0097] S3 Secondary Formation: After cleaning the etched foil that has undergone primary formation with deionized water, it is placed in the secondary formation treatment solution (the secondary formation treatment solution is NH4H2PO4, NaH2PO4, (NH4)2HPO4, Na2HPO4, Na5P3O4). 10 The secondary formation is carried out in an aqueous solution of at least one of (NaPO3)6, hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, and ethylenediaminetetramethylenephosphonic acid, wherein the mass percentage of the solute in the secondary formation treatment solution is 0.1%-0.8%. The secondary formation voltage is 120V-220V, the secondary formation time is 200s-400s, the secondary formation temperature is 70℃-90℃, and the secondary formation current density is 10 mA / cm². 2 -25 mA / cm 2 .

[0098] S4 Repair Treatment: After cleaning the etched foil that has undergone secondary formation with deionized water, it is placed in the repair treatment solution (the repair treatment solution is an aqueous solution of lanthanum nitrate and / or cerium nitrate, wherein the mass percentage of lanthanum nitrate and / or cerium nitrate is 0.2%-4%) for repair treatment. The repair treatment temperature is 30℃-85℃ and the repair treatment time is 2 min-10 min.

[0099] S5 Three-Stage Formation: After cleaning the repaired etched foil with deionized water, it is placed in a three-stage formation solution (a mixed aqueous solution of boric acid and citric acid, where the mass percentage of boric acid is 2%-10% and the mass percentage of citric acid is 0.2%-2%) for three-stage formation. The formation voltage is 420V-500V, the formation time is 550s-650s, the formation temperature is 70℃-90℃, and the formation current density is 15 mA / cm². 2 -25 mA / cm 2 .

[0100] S6 Quadruple Formation: After cleaning the etched foil that has undergone tertiary formation with deionized water, it is placed in a quaternary formation solution (a mixed aqueous solution of boric acid and citric acid, wherein the mass percentage of boric acid is 2%-10% and the mass percentage of citric acid is 0.2%-2%) for quaternary formation. The formation voltage for quaternary formation is 520V-600V, the formation time is 900s-1200s, the formation temperature is 70℃-90℃, and the formation current density is 15 mA / cm². 2 -25 mA / cm 2 .

[0101] S7 First Depolarization Treatment: After cleaning the etched foil after the fourth-stage formation with deionized water, it is placed in the first depolarization treatment solution (the first depolarization treatment solution is a phosphoric acid aqueous solution, in which the mass percentage of phosphoric acid is 4%-6%) for the first depolarization treatment. The temperature of the first depolarization treatment is 40℃-60℃, and the time of the first depolarization treatment is 120s-240s.

[0102] S8 First heat treatment: After the first depolarization treatment, the etched foil is cleaned with deionized water and placed in an environment of 500℃-600℃ for 100s-240s.

[0103] S9 First Re-forming Treatment: After the first heat treatment, the etched foil is cleaned with deionized water and then placed in the first re-forming treatment solution (the first re-forming treatment solution is a boric acid aqueous solution, in which the mass percentage of boric acid is 2%-10%) for the first re-forming treatment. The first re-forming voltage is 570V-590V, the first re-forming time is 400s-500s, the first re-forming temperature is 70℃-90℃, and the first re-forming current density is 15 mA / cm². 2 -25 mA / cm 2 .

[0104] S10 Second Depolarization Treatment: After cleaning the etched foil after the first re-forming treatment with deionized water, it is placed in the second depolarization treatment solution (the second depolarization treatment solution is a phosphoric acid aqueous solution, in which the mass percentage of phosphoric acid is 6%-8%) for the second depolarization treatment. The temperature of the second depolarization treatment is 60℃-70℃, and the time of the second depolarization treatment is 120s-600s.

[0105] S11 Second Re-forming Treatment: After cleaning the etched foil from the second depolarization treatment with deionized water, it is placed in the second re-forming treatment solution (the second re-forming treatment solution is a boric acid aqueous solution, in which the mass percentage of boric acid is 2%-10%) for the second re-forming treatment. The re-forming voltage for the second re-forming treatment is 570V-590V, the treatment time is 400s-500s, the temperature is 70℃-90℃, and the current density is 15 mA / cm². 2 -25 mA / cm 2 .

[0106] S12 Second Heat Treatment: After cleaning the etched foil after the second re-forming treatment with deionized water, place it in an environment of 500℃-600℃ for 100s-240s.

[0107] S13 Third Re-forming Treatment: After cleaning the etched foil from the second heat treatment with deionized water, it is placed in the third re-forming treatment solution (the third re-forming treatment solution is a boric acid aqueous solution, in which the mass percentage of boric acid is 2%-10%) for the third re-forming treatment. The re-forming voltage for the third re-forming treatment is 570V-590V, the treatment time is 400s-500s, the temperature is 70℃-90℃, and the current density is 15 mA / cm². 2 -25 mA / cm 2 .

[0108] S14 Stabilization Treatment: After cleaning the etched foil after the third re-forming treatment with deionized water, it is placed in the stabilization treatment solution (the stabilization treatment solution is an aqueous solution of ammonium dihydrogen phosphate, wherein the mass percentage of ammonium dihydrogen phosphate is 0.5%-3%) for stabilization treatment. The stabilization treatment temperature is 50℃-70℃ and the stabilization treatment time is 60s-240s.

[0109] S16 Drying treatment: After the stabilization treatment, the etched foil is cleaned with deionized water and then dried at 220℃-280℃ for 150s-240s to obtain the electrode foil.

[0110] The embodiments of the present invention will be described in detail below with reference to specific examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific conditions are not specified in the examples, the conditions described in the instruction manual, conventional conditions, or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0111] Example 1 S1 Water Boiling Pretreatment: The etched foil, after being cleaned with deionized water, is placed in boiling water for 12 minutes.

[0112] S2 Primary Formation: After the pre-treated etched foil is cleaned with deionized water, it is placed in the primary formation solution (a mixed aqueous solution of boric acid and ammonium pentaborate, wherein the mass percentage of boric acid is 5% and the mass percentage of ammonium pentaborate is 0.6%) for primary formation. The formation voltage is 90V, the formation time is 150s, the formation temperature is 85℃, and the formation current density is 10 mA / cm². 2 .

[0113] S3 Secondary Formation: After cleaning the etched foil that has undergone primary formation with deionized water, it is placed in the secondary formation solution (an aqueous solution of ammonium dihydrogen phosphate, with an ammonium dihydrogen phosphate mass percentage of 0.16%) for secondary formation. The formation voltage is 180V, the formation time is 300s, the formation temperature is 85℃, and the formation current density is 15 mA / cm². 2 .

[0114] S4 Repair Treatment: After cleaning the etched foil that has undergone secondary formation with deionized water, it is placed in the repair treatment solution (the repair treatment solution is an aqueous solution of cerium nitrate, wherein the mass percentage of cerium nitrate is 2%) for repair treatment. The repair treatment temperature is 55℃ and the repair treatment time is 6 min.

[0115] S5 Three-Stage Formation: After cleaning the repaired etched foil with deionized water, it is placed in a three-stage formation solution (a mixed aqueous solution of boric acid and citric acid, wherein the mass percentage of boric acid is 6% and the mass percentage of citric acid is 0.2%) for three-stage formation. The formation voltage is 460V, the formation time is 600s, the formation temperature is 85℃, and the formation current density is 20 mA / cm². 2 .

[0116] S6 Quadruple Formation: After cleaning the etched foil that has undergone tertiary formation with deionized water, it is placed in a quaternary formation solution (a mixed aqueous solution of boric acid and citric acid, wherein the mass percentage of boric acid is 6% and the mass percentage of citric acid is 0.2%) for quaternary formation. The formation voltage for quaternary formation is 580V, the formation time is 1000s, the formation temperature is 85℃, and the formation current density is 20 mA / cm². 2 .

[0117] S7 First Depolarization Treatment: After the etched foil after the fourth-stage formation is cleaned with deionized water, it is placed in the first depolarization treatment solution (the first depolarization treatment solution is a phosphoric acid aqueous solution, in which the mass percentage of phosphoric acid is 5%) for the first depolarization treatment. The temperature of the first depolarization treatment is 45℃ and the time of the first depolarization treatment is 180s.

[0118] S8 First heat treatment: After the first depolarization treatment, the etched foil is cleaned with deionized water and placed in an environment of 550℃ for 120s.

[0119] S9 First Re-forming Treatment: After the etched foil following the first heat treatment is cleaned with deionized water, it is placed in the first re-forming treatment solution (the first re-forming treatment solution is a boric acid aqueous solution, wherein the mass percentage of boric acid is 8%) for the first re-forming treatment. The first re-forming voltage is 580V, the first re-forming time is 450s, the first re-forming temperature is 85℃, and the first re-forming current density is 20 mA / cm². 2 .

[0120] S10 Second Depolarization Treatment: After cleaning the etched foil after the first re-forming treatment with deionized water, it is placed in the treatment solution for the second depolarization treatment (the treatment solution for the second depolarization treatment is an aqueous solution of phosphoric acid, in which the mass percentage of phosphoric acid is 7%) for the second depolarization treatment. The temperature of the second depolarization treatment is 65℃ and the time of the second depolarization treatment is 360s.

[0121] S11 Second Re-forming Treatment: After cleaning the etched foil following the second depolarization treatment with deionized water, it is placed in the second re-forming treatment solution (a boric acid aqueous solution with a boric acid mass percentage of 8%) for the second re-forming treatment. The re-forming voltage is 580V, the treatment time is 450s, the temperature is 85℃, and the current density is 20 mA / cm². 2 .

[0122] S12 Second Heat Treatment: After cleaning the etched foil after the second re-forming treatment with deionized water, place it in an environment of 550℃ for 120s.

[0123] S13 Third Re-forming Treatment: After cleaning the etched foil from the second heat treatment with deionized water, it is placed in the third re-forming treatment solution (the third re-forming treatment solution is a boric acid aqueous solution, in which the mass percentage of boric acid is 8%) for the third re-forming treatment. The re-forming voltage for the third re-forming treatment is 580V, the treatment time is 450s, the treatment temperature is 85℃, and the current density for the third re-forming treatment is 20 mA / cm². 2 .

[0124] S14 Stabilization Treatment: After cleaning the etched foil after the third re-forming treatment with deionized water, it is placed in the stabilization treatment solution (the stabilization treatment solution is an aqueous solution of ammonium dihydrogen phosphate, in which the mass percentage of ammonium dihydrogen phosphate is 2%) for stabilization treatment. The stabilization treatment temperature is 60℃ and the stabilization treatment time is 120s.

[0125] S16 Drying treatment: After the stabilization treatment, the etched foil is washed with water and then dried at 250°C for 180s to obtain the electrode foil.

[0126] Example 2 The difference between Example 2 and Example 1 is that the secondary formation treatment solution is an aqueous solution of aminotrimethylenephosphonic acid (the mass percentage of aminotrimethylenephosphonic acid is 0.32%), and the other conditions are the same as in Example 1.

[0127] Example 3 The difference between Example 3 and Example 1 is that the treatment solution for the repair treatment is an aqueous solution of lanthanum nitrate (the mass percentage of lanthanum nitrate is 3%), while the other conditions are the same as in Example 1.

[0128] Example 4 The difference between Example 4 and Example 1 is that the repair process takes 10 minutes, while the other conditions remain the same as in Example 1.

[0129] Example 5 The difference between Example 5 and Example 1 is that the temperature of the repair treatment is 45°C, while the other conditions are the same as in Example 1.

[0130] Comparative Example 1 (Introduce element P first, then element B) S1 Water Boiling Pretreatment: Place the etched foil in boiling water for 12 min.

[0131] S2 Primary Formation: After the pre-treated etched foil is cleaned with deionized water, it is placed in the primary formation solution (an aqueous solution of ammonium dihydrogen phosphate, with an ammonium dihydrogen phosphate mass percentage of 0.16%) for primary formation. The primary formation voltage is 180V, the primary formation time is 300s, the primary formation temperature is 85℃, and the primary formation current density is 15 mA / cm². 2 .

[0132] S3 Repair Treatment: After cleaning the etched foil that has undergone primary formation with deionized water, it is placed in the repair treatment solution (the repair treatment solution is an aqueous solution of cerium nitrate, wherein the mass percentage of cerium nitrate is 2%) for repair treatment. The repair treatment temperature is 55℃ and the repair treatment time is 6 min.

[0133] S4 Secondary Formation: After cleaning the repaired etched foil with deionized water, it is placed in a secondary formation solution (a mixed aqueous solution of boric acid and ammonium pentaborate, where the mass percentage of boric acid is 5% and the mass percentage of ammonium pentaborate is 0.6%) for secondary formation. The formation voltage is 90V, the formation time is 150s, the formation temperature is 85℃, and the formation current density is 10 mA / cm². 2 .

[0134] The remaining conditions remain the same as in Example 1.

[0135] Comparative Example 2 (No repair treatment) No step S4 repair process was performed; all other conditions remained the same as in Example 1.

[0136] Comparative Example 3 (without introducing element P) The secondary formation without step S3 was performed, and the remaining conditions remained the same as in Example 1.

[0137] Comparative Example 4 (using sodium nitrate instead of cerium nitrate) The difference between Comparative Example 4 and Example 1 is that the treatment solution for the repair treatment is an aqueous solution of sodium nitrate (sodium nitrate content of 2% by mass), while the other conditions are the same as those in Example 1.

[0138] Test data The electrode foils obtained in Examples 1-5 and Comparative Examples 1-4 were tested for various parameters. According to the standards in the China Electronic Components Association group standard T / CECA 22-2017 "Electrode Foil for Aluminum Electrolytic Capacitors", the boost time Tr, withstand voltage Vt, specific capacitance Cap, and leakage current LC of the formed foil were tested; among them, The boost time Tr refers to the time required to boost the voltage of the formed foil to 90% of the rated formation voltage (Vf) at a specified current density and temperature. The withstand voltage value Vt refers to the voltage value reached 180 seconds after the start of the voltage boosting process; both Vt and Tr are obtained by testing with a TV tester. Specific capacity Cap (μF / cm) 2 Cap refers to the capacitance per unit area of ​​the electrolytic foil after a withstand voltage test; Cap is obtained using an LCR digital bridge test. The leakage current LC was obtained by simulating the use scenario of aluminum electrolytic capacitors and conducting 15-hour IT curve tests on the formed foil of different embodiments and comparative examples. Energy consumption (kWh / m 2 The amount of electricity required for formation can be directly obtained during the electrode foil formation process using the TS680 small-sample formation process analyzer. The CV product, which is the product of specific capacitance and withstand voltage, provides a more fundamental and efficient measure of the "energy storage capacity" and "performance density" of the electrode foil. The results are shown in Table 1.

[0139] Table 1

[0140] Analyze the data in the table: (1) Compared with Examples 1-5, Comparative Examples 1-4 show that the electrode foil prepared by the preparation method provided by the present invention has a significantly improved specific capacity and CV product, while having a lower leakage current.

[0141] (2) Comparing Comparative Example 1 with Example 1, it is shown that although the use of phosphorus element treatment liquid for primary formation has a slight capacity-enhancing effect, it has high energy consumption and high production cost. Moreover, the electrode foil prepared by the preparation method provided in Comparative Example 1 has a high leakage current.

[0142] (3) Compared with Example 1, Comparative Examples 2 and 4 show that rare earth ions (Ce) are used in the preparation method provided by the present invention. 3+ and / or La 3+Phosphorus can fill the lattice gaps or oxygen vacancies in the alumina film caused by phosphorus doping, forming a "defect plugging" effect. This reduces the migration channels of ions in the treatment solution through the defects, thus lowering the leakage current of the prepared electrode foil. At the same time, rare earth ions react with hydroxyl (-OH) groups on the film surface to generate hydroxides such as Ce(OH)3 or La(OH)3. These hydroxides are further dehydrated to form CeO2 and La2O3 nanoparticles, which are uniformly embedded in the phosphorus-doped alumina film. This is equivalent to forming "structural support points" inside the film, improving the mechanical strength and crack resistance of the film, increasing the withstand voltage of the prepared electrode foil, and increasing the CV product of the prepared electrode foil. The higher the CV product, the better the performance of the electrode foil.

[0143] (4) Comparing Comparative Example 3 with Example 1, it is shown that in the preparation method provided by the present invention, while low-voltage anodic oxidation (secondary formation) is carried out in the treatment solution containing phosphorus to promote the formation of crystalline Al2O3 film, a certain dissolution effect is produced on amorphous Al2O3 (formed by boiling in water under heating conditions). Therefore, the specific volume and CV product of the obtained electrode foil can be further improved.

[0144] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0145] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing an electrode foil, characterized in that, The preparation method includes: performing primary formation, secondary formation, repair treatment, and tertiary formation on aluminum foil; The primary and tertiary formations are each carried out independently in a treatment solution containing boron. The secondary formation is carried out in a treatment solution containing phosphorus. The repair treatment is carried out in a treatment solution containing rare earth ions.

2. The preparation method according to claim 1, characterized in that, The primary formation treatment solution is a treatment solution containing boron. The primary formation treatment solution includes at least one of boric acid and ammonium pentaborate; Optionally, the primary formation treatment solution is a mixed aqueous solution of boric acid and ammonium pentaborate; Optionally, the boric acid content in the primary formation treatment solution is 3%-8% by mass; Optionally, the mass percentage of ammonium pentaborate in the primary formation treatment solution is 0.2%-0.8%; Optionally, the formation voltage of the first-stage formation is 60V-110V; Optionally, the temperature of the primary formation is 70℃-90℃; Optionally, the time for the first-stage formation is 90s-300s; Optionally, the current density of the first-stage formation is 5 mA / cm². 2 -15 mA / cm 2 .

3. The preparation method according to any one of claims 1 or 2, characterized in that, The secondary formation treatment solution is a treatment solution containing phosphorus. The secondary formation treatment solution includes NH4H2PO4, NaH2PO4, (NH4)2HPO4, Na2HPO4, and Na5P3O. 10 At least one of (NaPO3)6, hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, and ethylenediaminetetramethylenephosphonic acid; Optionally, the secondary formation treatment solution is NH4H2PO4, NaH2PO4, (NH4)2HPO4, Na2HPO4, or Na5P3O. 10 An aqueous solution of at least one of (NaPO3)6, hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, and ethylenediaminetetramethylenephosphonic acid; Optionally, the mass percentage of solute in the secondary formation treatment solution is 0.1%-0.8%; Optionally, the formation voltage of the secondary formation is 120V-220V; Optionally, the temperature of the secondary formation is 70℃-90℃; Optionally, the secondary formation time is 200s-400s; Optionally, the current density of the secondary formation is 10 mA / cm². 2 -25 mA / cm 2 .

4. The preparation method according to any one of claims 1-3, characterized in that, The treatment solution for the repair process is a treatment solution containing rare earth ions; The treatment solution for the repair process includes at least one of cerium nitrate and lanthanum nitrate. Optionally, the treatment solution for the repair treatment is an aqueous solution of lanthanum nitrate and / or cerium nitrate; Optionally, the mass percentage of lanthanum nitrate and / or cerium nitrate in the treatment solution for the remediation treatment is 0.2%-4%; Optionally, the temperature for the repair treatment is 30℃-85℃; Optionally, the repair process takes 2 to 10 minutes.

5. The preparation method according to any one of claims 1-4, characterized in that, The preparation method further includes: pre-treating the aluminum foil by boiling it in water before primary formation; Optionally, the boiling pretreatment includes: placing the aluminum foil in boiling water for 5 min to 20 min; Optionally, the preparation method includes: performing a fourth-stage formation after a third-stage formation; Optionally, the fourth-stage formation is carried out in a treatment solution containing boron. Optionally, the treatment solutions for the third-stage and fourth-stage formation are each independently a treatment solution containing boron. Optionally, the treatment solutions for the third-stage and fourth-stage formations each independently include boric acid and citric acid; Optionally, the treatment solutions for the third-stage and fourth-stage formation are each independently a mixed aqueous solution of boric acid and citric acid; Optionally, the mass percentage of boric acid in the treatment solutions of the third-stage and fourth-stage formation is independently 2%-10%; Optionally, the mass percentage of citric acid in the treatment solutions of the third-stage and fourth-stage formation is independently 0.2%-2%; Optionally, the formation voltage of the three-stage formation is 420V-500V; Optionally, the temperature of the tertiary formation is 70℃-90℃; Optionally, the time for the three-stage formation is 550s-650s; Optionally, the current density of the three-stage formation is 15 mA / cm². 2 -25 mA / cm 2 ; Optionally, the formation voltage of the four-stage formation is 520V-600V; Optionally, the temperature of the fourth-stage formation is 70℃-90℃; Optionally, the time for the fourth-level formation is 900s-1200s; Optionally, the current density of the four-stage formation is 15 mA / cm². 2 -25 mA / cm 2 .

6. The preparation method according to any one of claims 1-5, characterized in that, The preparation method further includes depolarization treatment, heat treatment, remodeling treatment and stabilization treatment; Optionally, the depolarization process includes a first depolarization process and a second depolarization process; Optionally, the heat treatment includes a first heat treatment and a second heat treatment; Optionally, the repair forming process includes a first repair forming process, a second repair forming process, and a third repair forming process; Optionally, the depolarization treatment is carried out in an aqueous phosphoric acid solution; Optionally, the mass percentage of phosphoric acid in the treatment solution of the first depolarization treatment is 4%-6%; Optionally, the temperature of the first depolarization treatment is 40℃-60℃; Optionally, the duration of the first depolarization process is 120s-240s; Optionally, the mass percentage of phosphoric acid in the treatment solution of the second depolarization treatment is 6%-8%; Optionally, the temperature of the second depolarization treatment is 60℃-70℃; Optionally, the second depolarization process takes 120s-600s; Optionally, the temperatures of the first heat treatment and the second heat treatment are each independently 500℃-600℃; Optionally, the duration of the first heat treatment and the second heat treatment is independently 100s-240s.

7. The preparation method according to any one of claims 1-6, characterized in that, The first, second, and third formation treatments are each carried out independently in a boric acid aqueous solution; Optionally, the mass percentage of boric acid in the treatment solutions of the first, second, and third re-formation treatments is independently 2%-10%; Optionally, the forming voltages for the first forming process, the second forming process, and the third forming process are each independently 570V-590V; Optionally, the time for the first, second, and third re-forming processes is independently 400s-500s; Optionally, the temperatures of the first, second, and third re-forming processes are each independently 70°C-90°C; Optionally, the current density of the first, second, and third re-forming processes is each independently 15 mA / cm². 2 -25 mA / cm 2 ; Optionally, the stabilization treatment is carried out in an aqueous solution of ammonium dihydrogen phosphate; Optionally, the mass percentage of ammonium dihydrogen phosphate in the stabilization treatment solution is 0.5%-3%; Optionally, the stabilization treatment temperature is 50℃-70℃; Optionally, the stabilization treatment time is 60s-240s.

8. The preparation method according to any one of claims 1-7, characterized in that, The preparation method further includes washing with water before any of the treatments; Optionally, the preparation method further includes washing with water after stabilization treatment and then drying. Optionally, the drying temperature is 220℃-280℃; Optionally, the drying time is 150s-240s; Optionally, the aluminum foil is an etched foil.

9. An electrode foil, characterized in that, The electrode foil is prepared by any one of claims 1-8.

10. An aluminum electrolytic capacitor, characterized in that, The aluminum electrolytic capacitor includes an electrode foil prepared by any one of claims 1-8 or the electrode foil described in claim 9.

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