Medium-high voltage formed foil and manufacturing method thereof

Abstract

The invention provides a manufacturing method of a medium-high voltage formed foil. The manufacturing method comprises the following steps: carrying out pretreatment on an aluminum foil by using a hydrogel pretreatment solution containing polycations and polyanions; and performing multi-stage formation treatment on the pretreated aluminum foil by using formation liquid. The invention further provides the medium-high voltage formed foil obtained through the manufacturing method. The flexibility of the formed foil is improved while the hydration resistance of the formed foil is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electrode foils, and in particular to a method for manufacturing a medium- and high-voltage chemically formed foil and a medium- and high-voltage chemically formed foil. Background Art

[0002] To improve the conductivity of the electrolyte in aluminum electrolytic capacitors and reduce the capacitor's equivalent series resistance (ESR), the water content of the electrolyte is typically increased. However, this causes the water to react with the oxide film on the aluminum foil surface, degrading the capacitor's performance or even causing it to fail. Phosphates are often used to treat the oxide film with hydration resistance to improve the foil's hydration resistance. However, this treatment can make the oxide film too thick, easily causing a sudden drop in capacitance. Furthermore, the high hardness and brittleness of crystalline aluminum oxide can cause defects such as microcracks and pinholes on the foil's surface, reducing the foil's ductility and flexibility, and even increasing the capacitor's ESR and shortening its lifespan. Summary of the Invention

[0003] The present disclosure provides a method for manufacturing a medium- and high-voltage chemically formed foil and a medium- and high-voltage chemically formed foil obtained by the manufacturing method.

[0004] The present invention provides a method for manufacturing a medium- and high-voltage chemically-formed foil, comprising the following steps: pre-treating an aluminum foil using a hydrogel pre-treatment solution containing polycations and polyanions; and performing a multi-stage chemically-formed treatment on the pre-treated aluminum foil using the chemically-formed solution.

[0005] According to the method for manufacturing a medium- and high-pressure chemically formed foil disclosed herein, the hydrogel pretreatment solution comprises a polycationic compound having a protonated amine group and a polyanionic compound having a sulfonic acid group.

[0006] According to the method for manufacturing a medium- and high-pressure chemically formed foil disclosed herein, the polycationic compound having a protonated amine group includes at least one of polyethyleneimine and chitosan; and the polyanionic compound having a sulfonic acid group includes polystyrene sulfonic acid.

[0007] According to the method for manufacturing medium- and high-pressure chemically formed foil disclosed herein, the hydrogel pretreatment liquid contains 1-5w% polyethyleneimine, 5-10w% chitosan, 1-10w% polystyrene sulfonic acid, 2-10w% ammonium succinate, 1-2w% glutaraldehyde, and 5-10w% polyvinyl alcohol; the temperature for pretreatment of the aluminum foil is 60-90°C and the time is 30-50 minutes.

[0008] According to the method for manufacturing medium- and high-voltage chemical-formed foil disclosed herein, the chemical-formed liquid comprises at least one of a piperidine-based ionic liquid, a sulfonic acid-based ionic liquid, and a thiophene-based polymer.

[0009] According to the method for manufacturing medium- and high-voltage chemical foil disclosed herein, the piperidine ionic liquid includes 1-ethyl-1-methylpiperidinium dihydrogen phosphate, the sulfonic acid ionic liquid includes polystyrene sulfonic acid, and the thiophene polymer includes poly-3,4-methylenedioxythiophene. According to the method for manufacturing medium- and high-voltage chemical foil disclosed herein, the chemical liquid for at least one primary chemical treatment includes 0.01-0.5w% glycerol, 0.01-2w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.01-2w% polystyrene sulfonic acid, and 0.01-2w% poly-3,4-methylenedioxythiophene.

[0010] According to the method for manufacturing medium- and high-voltage chemically formed foil disclosed herein, the chemical forming liquid of at least one stage of chemical forming treatment contains 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, and 0.01-2w% chitosan.

[0011] According to the method for manufacturing medium- and high-voltage chemical foil disclosed herein, the chemical solution of at least one stage of chemical treatment contains 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, 0.01-2w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.01-2w% chitosan.

[0012] The method for manufacturing the medium- and high-voltage chemically formed foil according to the present disclosure further includes: performing at least one intermediate treatment on the aluminum foil between the multi-stage chemically formed treatments.

[0013] According to the manufacturing method of medium- and high-voltage chemical foil disclosed in the present invention, the aluminum foil is subjected to at least one intermediate treatment between the multi-stage chemical treatments, including: a first intermediate treatment of the aluminum foil using an aqueous solution containing a phosphoric acid substance; and a second intermediate treatment of the aluminum foil using an aqueous solution containing an organic acid.

[0014] According to the manufacturing method of the medium- and high-pressure chemically formed foil disclosed herein, the aqueous solution containing phosphoric acid substances includes 1-5w% phosphoric acid and 0.01-2w% ammonium succinate; the aqueous solution containing organic acid includes 1-10w% benzoic acid and 0.01-2w% sodium alginate.

[0015] According to the method for manufacturing the medium- and high-pressure chemically formed foil disclosed herein, before pre-treating the aluminum foil with a hydrogel pre-treatment solution containing polycations and polyanions, the method further includes: hydrating the aluminum foil with deionized water.

[0016] The method for manufacturing the medium- and high-voltage chemically formed foil according to the present disclosure further includes a heat treatment step performed after the multi-stage chemically formed treatment.

[0017] According to the method for manufacturing a medium- and high-pressure chemically formed foil disclosed herein, the heat treatment includes annealing the aluminum foil in an inert atmosphere.

[0018] The present disclosure also provides a medium- and high-pressure chemically formed foil obtained by the above-mentioned manufacturing method.

[0019] The present invention pre-treats aluminum foil with a hydrogel pre-treatment solution containing polycations and polyanions, forming a polyelectrolyte complex through electrostatic interaction. This results in a three-dimensional network-structured polymer film on the surface of the corroded aluminum foil and the inner walls of the corrosion holes. This film inhibits ion corrosion and blocks the pores in the corroded foil, thereby preventing the excessive growth of the hydrated oxide film. Furthermore, the multi-stage chemical conversion process improves the hydration resistance of the chemically converted foil. In other words, the present invention avoids excessive thickness of the oxide film on the chemically converted foil and introduces a flexible polymer, thereby significantly enhancing the flexibility of the chemically converted foil while improving its hydration resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of a method for manufacturing a medium- and high-voltage chemically formed foil according to one embodiment of the present disclosure.

[0021] Figure 2 is a flow chart of a method for manufacturing a medium- and high-voltage chemically formed foil according to another embodiment of the present disclosure.

[0022] Figure 3 This is a microscopic morphology image of the medium- and high-pressure chemically formed foil manufactured according to Example 1 of the present disclosure.

[0023] Figure 4 This is a microscopic morphology image of the medium- and high-pressure chemically formed foil manufactured according to Example 2 of the present disclosure.

[0024] Figure 5 This is a microscopic morphology image of the medium- and high-pressure chemically formed foil manufactured according to Example 3 of the present disclosure.

[0025] Figure 6 This is a microscopic morphology image of a medium- and high-pressure electrochemical foil manufactured according to the comparative example method of the present disclosure. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the technical solution of the present disclosure is described in detail below with reference to the accompanying drawings.

[0027] Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art.

[0028] In the absence of conflict, the various embodiments of the present disclosure and the various features therein may be combined with each other.

[0029] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0030] The terms used herein are used only to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a," "an," and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "made of" are used in this specification, the presence of the features, wholes, steps, operations, elements, and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof is not excluded.

[0031] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined as such herein.

[0032] The present invention provides a method for manufacturing a medium- and high-voltage chemically formed foil, referring to Figure 1 , including the following steps: S1. Pretreatment: Pretreating the aluminum foil with a hydrogel pretreatment solution containing polycations and polyanions; S2. Multi-stage chemical conversion treatment: using a chemical conversion liquid to perform a multi-stage chemical conversion treatment on the pre-treated aluminum foil.

[0033] The pretreatment utilizes a hydrogel containing polycations and polyanions to form a polyelectrolyte complex through electrostatic action, thereby forming a polymer film with a three-dimensional network structure on the surface of the corroded aluminum foil and the inner wall of the corrosion holes, inhibiting ion corrosion and blocking the small holes of the corroded foil, thereby preventing the hydrated oxide film from continuing to grow; at the same time, the introduction of the flexible polymer greatly reduces the brittleness of the corroded foil.

[0034] The hydrogel containing polycations and polyanions comprises a polycationic compound having a protonated amine group and a polyanionic compound having a sulfonic acid group.

[0035] The polycationic compound having protonated amine groups includes at least one of polyethyleneimine and chitosan; the polyanionic compound having sulfonic acid groups is polystyrenesulfonic acid. Polycations and polyanions are dispersed in the hydrogel formed by cross-linking polyethyleneimine or chitosan with polyvinyl alcohol via pentanediol. Preferably, the hydrogel containing polycations and polyanions comprises two polycations and one polyanion, forming a "polycation-polyanion-polycation" sandwich structure.

[0036] In some embodiments, the hydrogel pretreatment solution comprises 1-5w% polyethyleneimine, 5-10w% chitosan, 1-10w% polystyrene sulfonic acid, 2-10w% ammonium succinate, 1-2w% glutaraldehyde, and 5-10w% polyvinyl alcohol; the pretreatment temperature of the aluminum foil is 60-90° C. and the time is 30-50 minutes.

[0037] The multi-stage chemical formation process uses a chemical formation liquid to gradually dehydrate the hydrated oxide film to form a crystalline oxide film. The chemical formation liquid contains at least one of a piperidine ionic liquid, a sulfonic acid ionic liquid, and a thiophene polymer. The thiophene polymer provides charged ions. The chemical formation liquid may also contain an alcohol substance, whose hydroxyl group reacts with Al 3+ Complexation, delaying local excessive oxidation.

[0038] In some embodiments, the piperidine-based ionic liquid includes 1-ethyl-1-methylpiperidinium dihydrogen phosphate, the sulfonic acid-based ionic liquid includes polystyrene sulfonic acid, and the thiophene-based polymer includes poly-3,4-methylenedioxythiophene.

[0039] In some embodiments, the forming liquid of at least one stage of forming treatment comprises 0.01-0.5 w % glycerol, 0.01-2 w % 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.01-2 w % polystyrene sulfonic acid, and 0.01-2 w % poly-3,4-methylenedioxythiophene.

[0040] In some embodiments, the chemical forming solution of at least one stage chemical forming treatment comprises 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, and 0.01-2w% chitosan.

[0041] The polyelectrolyte complex in the forming solution is adsorbed onto the surface of each oxide film through intermolecular forces, reducing damage to the film caused by the medium. The unique structural characteristics of polystyrene sulfonic acid and poly (3,4-methylenedioxythiophene) form a composite conductive layer on the surface of the oxide film, creating a three-dimensional conductive network. This hydrophilic structure allows the forming solution to more easily penetrate the nanopores of the corrosion foil, increasing the effective contact area and boosting energy storage density.

[0042] According to the manufacturing method of the medium and high voltage chemical foil disclosed in the present invention, it also includes one or more intermediate treatments of the aluminum foil between the multi-stage chemical treatments. The intermediate treatment step includes treating the aluminum foil with an aqueous solution containing a phosphoric acid substance or treating the aluminum foil with an aqueous solution containing an organic acid. The intermediate treatment with a phosphoric acid substance can generate a dense and high-resistance AlPO4 precipitate, fill vacuum and cracks, and reduce leakage current. In the intermediate treatment with an organic acid, the organic acid is used as an auxiliary ligand of phosphoric acid to form an Al-organic acid-phosphate ternary complex, thereby enhancing the stability of the oxide film. The phosphoric acid substance includes phosphoric acid, ammonium dihydrogen phosphate or potassium dihydrogen phosphate, etc. The organic acid includes benzoic acid, citric acid or tartaric acid, etc. The intermediate treatment can remove excess protective layer, purify the surface, and repair damage to the oxide film.

[0043] In some embodiments, the aluminum foil is subjected to at least one intermediate treatment between the multi-stage chemical treatments, including: a first intermediate treatment of the aluminum foil using an aqueous solution containing a phosphoric acid substance; and a second intermediate treatment of the aluminum foil using an aqueous solution containing an organic acid.

[0044] In some embodiments, the aqueous solution containing phosphoric acid comprises 1-5w% phosphoric acid and 0.01-2w% ammonium succinate; the aqueous solution containing organic acid comprises 1-10w% benzoic acid and 0.01-2w% sodium alginate.

[0045] The method for manufacturing a medium- and high-voltage chemically formed foil disclosed herein also includes hydrating the aluminum foil prior to pretreatment. This hydration treatment involves treating the aluminum foil with deionized water. This hydration treatment forms a layered hydrated oxide film approximately 5 nm thick on the surface of the etched foil and the inner walls of the etched holes. The hydroxyl groups are arranged in a layered pattern, and the hydrated oxide film improves the dielectric constant and optimizes the breakdown voltage.

[0046] The method for manufacturing a medium- and high-voltage chemically formed foil disclosed herein also includes a heat treatment step performed after the multi-stage chemically formed process. The heat treatment comprises annealing the aluminum foil in an inert atmosphere. This heat treatment can eliminate internal stress in the chemically formed foil, optimize grain orientation, and improve ductility.

[0047] According to one embodiment of the present disclosure, referring to Figure 2 The method for manufacturing the medium- and high-voltage chemically formed foil comprises: S1. Pre-treat the hydrated aluminum foil using a hydrogel pre-treatment solution containing polycations and polyanions During the hydration treatment process, the aluminum foil after chemical / electrochemical etching and expansion is treated with deionized water, and then the hydrated aluminum foil is placed in a hydrogel pretreatment solution containing polycations and polyanions and treated at an appropriate temperature.

[0048] For example, the hydrogel pretreatment solution contains polyethyleneimine, chitosan, polystyrene sulfonic acid, ammonium succinate, glutaraldehyde and polyvinyl alcohol.

[0049] S21, perform primary chemical treatment on the pre-treated aluminum foil The pre-treated aluminum foil is placed in an aqueous solution containing glycerol, 1-ethyl-1-methylpiperidinium dihydrogen phosphate, polystyrene sulfonic acid, and poly-3,4-methylenedioxythiophene, and treated at an appropriate temperature and voltage.

[0050] S22, perform secondary chemical treatment on the aluminum foil that has undergone primary chemical treatment The aluminum foil that has undergone primary chemical conversion treatment is washed with water and then placed in an aqueous solution containing glycerol, 1-ethyl-1-methylpiperidinium dihydrogen phosphate, polystyrene sulfonic acid, and poly-3,4-methylenedioxythiophene, and is treated at an appropriate temperature and voltage.

[0051] S3, carry out a secondary treatment on the aluminum foil after the secondary chemical treatment The aluminum foil that has undergone secondary chemical conversion treatment is washed with water and then placed in an aqueous solution containing phosphoric acid and ammonium succinate, and treated at an appropriate temperature.

[0052] S23, perform three-stage chemical treatment on the aluminum foil that has undergone the primary treatment The aluminum foil that has undergone the primary treatment is washed with water and then placed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, and chitosan, and treated at appropriate temperature and voltage.

[0053] S24, perform a fourth-stage chemical treatment on the aluminum foil that has undergone the third-stage chemical treatment The aluminum foil that has undergone the three-stage chemical treatment is washed with water and then placed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, and chitosan, and treated at appropriate temperature and voltage.

[0054] S4, secondary treatment of aluminum foil after four-stage chemical treatment The aluminum foil that has undergone the four-stage chemical treatment is washed with water and then placed in an aqueous solution containing benzoic acid and sodium alginate, and treated at an appropriate temperature.

[0055] S25, five-stage chemical treatment of the aluminum foil after secondary treatment The aluminum foil that has undergone the second treatment is washed with water and then placed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and chitosan, and treated at an appropriate temperature and voltage.

[0056] S5. Heat treatment of the aluminum foil after the five-stage chemical treatment The aluminum foil that has undergone the five-stage chemical treatment is washed with water and then annealed.

[0057] S26, perform six-stage chemical treatment on the heat-treated aluminum foil The heat-treated aluminum foil is washed with water and then placed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and chitosan, and treated at an appropriate temperature and voltage.

[0058] S6. Post-processing of aluminum foil after six-stage chemical treatment The aluminum foil that has undergone the six-stage chemical treatment is washed with water and then dried.

[0059] According to one embodiment of the present disclosure, the method for manufacturing the medium- and high-pressure chemically formed foil specifically includes: Hydration treatment: Immerse the aluminum foil after chemical / electrochemical etching in 90-100°C deionized water for 1-5 minutes to remove dust, foil ash and other impurities.

[0060] Pre-treatment: The hydrated aluminum foil is placed in a hydrogel containing 1-5w% polyethyleneimine, 5-10w% chitosan, 1-10w% polystyrene sulfonic acid, 2-10w% ammonium succinate, 1-2w% glutaraldehyde, and 5-10w% polyvinyl alcohol, and treated at 60-90°C for 30-50 minutes.

[0061] Primary chemical treatment: The pre-treated aluminum foil is placed in an aqueous solution containing 0.01-0.5w% glycerol, 0.01-2w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.01-2w% polystyrene sulfonic acid, and 0.01-2w% poly-3,4-methylenedioxythiophene, and treated at a temperature of 40-60°C and a voltage of 90-170V for 10-20 minutes.

[0062] Secondary chemical treatment: The aluminum foil that has undergone primary chemical conversion treatment is washed with water and placed in an aqueous solution containing 0.01-0.5w% glycerol, 0.01-2w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.01-2w% polystyrene sulfonic acid, and 0.01-2w% poly-3,4-methylenedioxythiophene, and treated at a temperature of 80-95°C and a voltage of 150-240V for 10-20 minutes.

[0063] First processing: The aluminum foil that has undergone secondary chemical treatment is washed with water and then placed in an aqueous solution containing 1-5w% phosphoric acid and 0.01-2w% ammonium succinate, and treated at a temperature of 30-45°C for 2-10 minutes.

[0064] Three-stage chemical treatment: The aluminum foil that has undergone the primary treatment is washed with water and then placed in an aqueous solution containing 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, and 0.01-2w% chitosan, and treated at a temperature of 40-60°C and a voltage of 250-340V for 10-20 minutes.

[0065] Four-stage chemical treatment: The aluminum foil that has undergone the three-stage chemical treatment is washed with water and then placed in an aqueous solution containing 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, and 0.01-2w% chitosan, and treated at a temperature of 80-95°C and a voltage of 350-440V for 10-20 minutes.

[0066] Second processing: The aluminum foil that has undergone the four-stage chemical treatment is washed with water and then placed in an aqueous solution containing 1-10w% benzoic acid and 0.01-2w% sodium alginate, and treated at a temperature of 30-45°C for 2-10 minutes.

[0067] Five-stage chemical treatment: The aluminum foil that has undergone the second treatment is washed with water and then placed in an aqueous solution containing 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, 0.01-2w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.01-2w% chitosan, and treated at a temperature of 40-60°C and a voltage of 450-540V for 10-20 minutes.

[0068] Heat treatment: The aluminum foil that has undergone the five-stage chemical treatment is washed with water and then annealed in a nitrogen atmosphere at a temperature of 350-550° C. for 2-10 minutes.

[0069] Six-stage chemical treatment: The heat-treated aluminum foil is washed with water and then placed in an aqueous solution containing 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, 0.01-2w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.01-2w% chitosan, and treated at a temperature of 80-95°C and a voltage of 550-660V for 10-20 minutes.

[0070] Post-processing: After washing the aluminum foil that has undergone the six-stage chemical treatment, dry it with hot air at 60-120℃ for 5-10 minutes to ensure that no moisture remains.

[0071] The present disclosure also provides a medium- and high-pressure chemically formed foil obtained according to the above manufacturing method.

[0072] The surface micromorphology of the medium and high voltage chemical foil obtained according to the manufacturing method disclosed in the present invention is a uniform and dense flocculent oxide film with a loose, porous, fibrous nanostructure. It has buffering, liquid storage, self-healing, and heat dissipation functions in capacitors. Its electrostatic capacitance, test withstand voltage, boost time, bending strength, tensile strength, and leakage current as a chemical foil are all superior to those of the chemical foil prepared by traditional processes.

[0073] In order to enable those skilled in the art to more clearly understand the technical solution of the present disclosure, the technical solution of the present disclosure is described in detail below through specific embodiments.

[0074] Example 1 Hydration treatment: The aluminum foil after chemical / electrochemical etching and expansion was immersed in 95°C deionized water for hydration treatment for 5 minutes.

[0075] Pretreatment: The hydrated aluminum foil was placed in a hydrogel of 1w% polyethyleneimine, 5w% chitosan, 1w% polystyrene sulfonic acid, 2w% ammonium succinate, 1w% glutaraldehyde, and 5w% polyvinyl alcohol and treated at 60°C for 30 minutes.

[0076] Primary chemical conversion treatment: the pre-treated aluminum foil was placed in an aqueous solution containing 0.01w% propylene glycol, 0.015w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.015w% polystyrene sulfonic acid, and 0.015w% poly-3,4-methylenedioxythiophene at 45°C, 110V, and 10 minutes.

[0077] Secondary chemical conversion treatment: The aluminum foil that has undergone primary chemical conversion treatment is washed with water and then placed in an aqueous solution containing 0.01w% propylene glycol, 0.015w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.015w% polystyrene sulfonic acid, and 0.015w% poly-3,4-methylenedioxythiophene at 85°C, 240V, and 20 minutes.

[0078] First intermediate treatment: After washing the aluminum foil that has undergone secondary chemical treatment, place it in a 1w% phosphoric acid and 0.01w% ammonium succinate aqueous solution at 35°C for 10 minutes.

[0079] Three-stage chemical treatment: After washing the aluminum foil after the first treatment, place it in an aqueous solution containing 0.015w% polyethyleneimine, 0.03w% polystyrene sulfonic acid, and 0.015w% chitosan at 45°C, 340V, and 15 minutes.

[0080] Four-stage chemical conversion treatment: The aluminum foil that has undergone the three-stage chemical conversion treatment is washed with water and then placed in an aqueous solution containing 0.015w% polyethyleneimine, 0.03w% polystyrene sulfonic acid, and 0.015w% chitosan at 85°C, 440V, and 20 minutes.

[0081] Second intermediate treatment: After washing the aluminum foil after the fourth-stage chemical treatment, place it in a 1w% benzoic acid and 0.01w% sodium alginate aqueous solution at 35°C for 5 minutes.

[0082] Five-stage chemical treatment: the aluminum foil after the second treatment was washed with water and placed in an aqueous solution containing 0.015w% polyethyleneimine, 0.03w% polystyrene sulfonic acid, 0.03w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.015w% chitosan at 45°C, 540V, and 15 minutes.

[0083] Heat treatment: The aluminum foil after the five-stage chemical treatment was washed with water and then annealed in a nitrogen atmosphere at 350°C for 2 minutes.

[0084] Six-stage chemical treatment: the heat-treated aluminum foil was washed with water and then placed in an aqueous solution containing 0.015w% polyethyleneimine, 0.03w% polystyrene sulfonic acid, 0.03w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.015w% chitosan at 85°C, 650V, and 20 minutes.

[0085] Post-processing: After washing the aluminum foil that has undergone the six-stage chemical treatment, dry it with hot air at 100°C for 10 minutes.

[0086] Example 2 Hydration treatment: The aluminum foil after chemical / electrochemical etching and expansion was immersed in 96°C deionized water for hydration treatment for 5 minutes.

[0087] Pretreatment: The hydrated aluminum foil was placed in a hydrogel of 3w% polyethyleneimine, 5w% chitosan, 8w% polystyrene sulfonic acid, 6w% ammonium succinate, 1w% glutaraldehyde, and 5w% polyvinyl alcohol and treated at 60°C for 40 minutes.

[0088] Primary chemical treatment: the pre-treated aluminum foil was placed in an aqueous solution containing 0.1w% propylene glycol, 0.1w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.1w% polystyrene sulfonic acid, and 0.1w% poly-3,4-methylenedioxythiophene at 45°C, 140V, and 15 minutes.

[0089] Secondary chemical conversion treatment: The aluminum foil that has undergone primary chemical conversion treatment was washed with water and then placed in an aqueous solution containing 0.1w% propylene glycol, 0.1w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.1w% polystyrene sulfonic acid, and 0.1w% poly-3,4-methylenedioxythiophene at 85°C, 240V, and 20 minutes.

[0090] First intermediate treatment: After washing the aluminum foil that has undergone secondary chemical treatment, place it in a 2w% phosphoric acid and 0.1w% ammonium succinate aqueous solution at 35°C for 10 minutes.

[0091] Three-stage chemical treatment: After washing the aluminum foil after the first treatment, place it in an aqueous solution containing 0.1w% polyethyleneimine, 0.2w% polystyrene sulfonic acid, and 0.1w% chitosan at 45°C, 340V, and 15 minutes.

[0092] Four-stage chemical conversion treatment: The aluminum foil that has undergone the three-stage chemical conversion treatment is washed with water and then placed in an aqueous solution containing 0.1w% polyethyleneimine, 0.2w% polystyrene sulfonic acid, and 0.1w% chitosan at 85°C, 440V, and 20 minutes.

[0093] Second intermediate treatment: After washing the aluminum foil after the fourth-stage chemical treatment, place it in a 5w% benzoic acid and 0.1w% sodium alginate aqueous solution at 35°C for 10 minutes.

[0094] Five-stage chemical treatment: the aluminum foil after the second treatment was washed with water and placed in an aqueous solution containing 0.1w% polyethyleneimine, 0.3w% polystyrene sulfonic acid, 0.3w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.15w% chitosan at 45°C, 540V, and 15 minutes.

[0095] Heat treatment: The aluminum foil after the five-stage chemical treatment was washed with water and then annealed in a nitrogen atmosphere at 450°C for 5 minutes.

[0096] Six-stage chemical treatment: the heat-treated aluminum foil was washed with water and then placed in an aqueous solution containing 0.1w% polyethyleneimine, 0.3w% polystyrene sulfonic acid, 0.3w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.15w% chitosan at 85°C, 650V, and 20 minutes.

[0097] Post-processing: After washing the aluminum foil that has undergone the six-stage chemical treatment, dry it with hot air at 100℃ for 10 minutes to ensure that no moisture remains.

[0098] Example 3 Hydration treatment: The aluminum foil after chemical / electrochemical etching and expansion was immersed in 96°C deionized water for hydration treatment for 5 minutes.

[0099] Pretreatment: The hydrated aluminum foil was placed in a hydrogel of 5w% polyethyleneimine, 10w% chitosan, 10w% polystyrene sulfonic acid, 5w% ammonium succinate, 2w% glutaraldehyde, and 10w% polyvinyl alcohol and treated at 80°C for 50 minutes.

[0100] Primary chemical treatment: the pre-treated aluminum foil was placed in an aqueous solution containing 0.5w% propylene glycol, 1.5w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 1.5w% polystyrene sulfonic acid, and 1.5w% poly-3,4-methylenedioxythiophene at 60°C, 110V, and 15 minutes.

[0101] Secondary chemical conversion treatment: the aluminum foil that has undergone primary chemical conversion treatment is washed with water and then placed in an aqueous solution containing 0.5w% propylene glycol, 1.5w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 1.5w% polystyrene sulfonic acid, and 1.5w% poly-3,4-methylenedioxythiophene at 90°C, 240V, and 20 minutes.

[0102] First intermediate treatment: Wash the aluminum foil that has undergone secondary chemical treatment with water and then place it in a 5w% phosphoric acid and 2% ammonium succinate aqueous solution at 35°C for 10 minutes.

[0103] Three-stage chemical treatment: After washing the aluminum foil after the first treatment, place it in an aqueous solution containing 1.5w% polyethyleneimine, 3w% polystyrene sulfonic acid, and 1.5w% chitosan at 60°C, 340V, and 15 minutes.

[0104] Four-stage chemical conversion treatment: The aluminum foil that has undergone the three-stage chemical conversion treatment is washed with water and then placed in an aqueous solution containing 1.5w% polyethyleneimine, 3w% polystyrene sulfonic acid, and 1.5w% chitosan at 95°C, 440V, and 20 minutes.

[0105] Second intermediate treatment: After washing the aluminum foil after the fourth-stage chemical treatment, place it in a 10w% benzoic acid and 2w% sodium alginate aqueous solution at 45°C for 10 minutes.

[0106] Five-stage chemical treatment: the aluminum foil after the second treatment was washed with water and placed in an aqueous solution containing 1.5w% polyethyleneimine, 3w% polystyrene sulfonic acid, 3w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 1.5w% chitosan at 60°C, 540V, and 20 minutes.

[0107] Heat treatment: The aluminum foil after the five-stage chemical treatment was washed with water and then annealed at 550°C in a nitrogen atmosphere for 5 minutes.

[0108] Six-stage chemical treatment: the heat-treated aluminum foil was washed with water and then placed in an aqueous solution containing 1.5w% polyethyleneimine, 3w% polystyrene sulfonic acid, 3w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 1.5w% chitosan at 95°C, 660V, and 20 minutes.

[0109] Post-processing: After washing the aluminum foil that has undergone the six-stage chemical treatment, dry it with hot air at 100°C for 10 minutes.

[0110] Comparative Example 1 Hydration treatment: The aluminum foil after chemical / electrochemical etching and expansion was immersed in 96°C deionized water for hydration treatment for 5 minutes.

[0111] Primary chemical treatment: put the hydrated aluminum foil into an aqueous solution containing 1w% boric acid, 0.02w% citric acid, 1.5w% polystyrene sulfonic acid, and 0.1w% ammonium pentaborate at 70°C, 200V, and 15 minutes.

[0112] Secondary chemical conversion treatment: The aluminum foil after the primary chemical conversion treatment was washed with water and placed in an aqueous solution containing 1w% boric acid, 0.02w% citric acid, 1.5w% polystyrene sulfonic acid, and 0.1w% ammonium pentaborate at 80°C, 400V, and 20 minutes.

[0113] Secondary treatment: After washing the aluminum foil that has undergone secondary chemical treatment, place it in a 2w% phosphoric acid and 0.2% benzoic acid aqueous solution at 60°C for 2 minutes.

[0114] Three-stage chemical treatment: After washing the treated aluminum foil, place it in an aqueous solution containing 2w% boric acid at 80°C, 550V, and 15 minutes.

[0115] Four-stage chemical conversion treatment: After washing the aluminum foil that has undergone the three-stage chemical conversion treatment, place it in an aqueous solution containing 2w% boric acid at 85°C, a voltage of 660V, and a time of 20 minutes.

[0116] Heat treatment: The aluminum foil after the four-stage chemical treatment was washed with water and then annealed at 550°C in a nitrogen atmosphere for 5 minutes.

[0117] Post-treatment: Wash the heat-treated aluminum foil with water and then place it in a 2w% phosphoric acid and 1w% boric acid aqueous solution at 60°C for 2 minutes.

[0118] Drying: After washing the post-treated aluminum foil with water, dry it with hot air at 100°C for 10 minutes.

[0119] The formed foils obtained in Examples 1-3 and Comparative Example 1 were used as formed foils to conduct electrical and mechanical property tests. The results are shown in Table 1.

[0120] Table 1 Test results of Examples 1 to 3 and Comparative Example 1 As can be seen from the table, the electrostatic capacitance, test withstand voltage, voltage rise time, bending strength, tensile strength and leakage current of the chemical foil prepared by the chemical forming method disclosed in the present invention are all superior to those of the chemical foil prepared by the traditional process. The enhancement of bending strength and tensile strength indicates that the ductility of the chemical foil prepared by the present invention is effectively improved.

[0121] Figure 3 、 Figure 4 、 Figure 5 They are respectively the microscopic morphology images of Examples 1-3, Figure 6This is a microscopic morphology image of comparative example 1. As can be seen from the figure, in the microscopic morphology of comparative example 1, there is obviously an over-formed oxide film that blocks some corrosion holes, which will reduce the electrostatic capacitance of the formed foil, and the excessively thick sheet-like oxide film will cause microcracks to form during the winding process of the formed foil, which directly affects the performance of the capacitor. The microscopic morphology of the formed foil prepared by the present invention is a uniform and dense flocculent oxide film with a loose, porous, fibrous nanostructure, which has the functions of buffering, liquid storage, self-healing, and heat dissipation in the capacitor. Therefore, the comprehensive performance of the formed foil prepared by the present invention is better than that of the formed foil prepared by the conventional forming method.

[0122] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly indicated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

1. A method for manufacturing a medium- and high-voltage formed foil, comprising: The aluminum foil is pretreated using a hydrogel pretreatment solution containing polycations and polyanions; The pre-treated aluminum foil is subjected to multi-stage chemical conversion treatment using a chemical conversion liquid.

2. The method for manufacturing a medium- and high-pressure chemically formed foil according to claim 1, wherein: The hydrogel pretreatment solution comprises a polycationic compound having a protonated amine group and a polyanionic compound having a sulfonic acid group.

3. The method for manufacturing a medium- and high-pressure chemically formed foil according to claim 2, wherein: The polycationic compound having a protonated amine group includes at least one of polyethyleneimine and chitosan; the polyanionic compound having a sulfonic acid group includes polystyrene sulfonic acid.

4. The method for producing a medium- and high-pressure chemically formed foil according to any one of claims 1 to 3, wherein: The hydrogel pretreatment solution contains 1-5w% polyethyleneimine, 5-10w% chitosan, 1-10w% polystyrene sulfonic acid, 2-10w% ammonium succinate, 1-2w% glutaraldehyde, and 5-10w% polyvinyl alcohol; the pretreatment temperature for the aluminum foil is 60-90° C., and the time is 30-50 minutes.

5. The method for manufacturing a medium- and high-pressure chemically formed foil according to any one of claims 1 to 3, wherein: The chemical formation liquid comprises at least one of a piperidine ionic liquid, a sulfonic acid ionic liquid, and a thiophene polymer.

6. The method for manufacturing a medium- and high-voltage chemically formed foil according to claim 5, wherein: The piperidine ionic liquid includes 1-ethyl-1-methylpiperidinium dihydrogen phosphate, the sulfonic acid ionic liquid includes polystyrene sulfonic acid, and the thiophene polymer includes poly-3,4-methylenedioxythiophene.

7. The method for manufacturing a medium- and high-voltage chemically formed foil according to claim 6, wherein: The chemical forming liquid of at least one stage chemical forming treatment comprises 0.01-0.5w% of glycerol, 0.01-2w% of 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.01-2w% of polystyrene sulfonic acid, and 0.01-2w% of poly-3,4-methylenedioxythiophene.

8. The method for manufacturing a medium- and high-voltage chemically formed foil according to claim 6, wherein: The chemical forming liquid of at least one stage chemical forming treatment comprises 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, and 0.01-2w% chitosan.

9. The method for manufacturing a medium- and high-voltage chemically formed foil according to claim 6, wherein: The chemical forming liquid of at least one stage chemical forming treatment comprises 0.01-2w% polyethyleneimine, 0.01-4w% polystyrene sulfonic acid, 0.01-2w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.01-2w% chitosan.

10. The method for manufacturing a medium- and high-pressure chemically formed foil according to any one of claims 1 to 3, wherein: Also includes: The aluminum foil is subjected to at least one intermediate treatment between the multi-stage chemical formation treatments.

11. The method for manufacturing a medium- and high-voltage chemically formed foil according to claim 10, wherein: The aluminum foil is subjected to at least one intermediate treatment between the multi-stage chemical treatments, including: The aluminum foil is subjected to a first intermediate treatment using an aqueous solution containing phosphoric acid; The aluminum foil is subjected to a second intermediate treatment using an aqueous solution containing an organic acid.

12. The method for manufacturing a medium- and high-voltage chemically formed foil according to claim 11, wherein: The aqueous solution containing phosphoric acid substances includes 1-5w% phosphoric acid and 0.01-2w% ammonium succinate; the aqueous solution containing organic acid includes 1-10w% benzoic acid and 0.01-2w% sodium alginate.

13. The method for producing a medium- and high-pressure chemically formed foil according to any one of claims 1 to 3, wherein: Before pre-treating the aluminum foil with the hydrogel pre-treatment solution containing polycations and polyanions, the method further includes: Hydrate the aluminum foil using deionized water.

14. A medium-high voltage chemically formed foil, obtained by the method for manufacturing a medium-high voltage chemically formed foil according to any one of claims 1 to 13.

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