Medium-high voltage formed foil and method of manufacturing the same

Abstract

The present disclosure provides a method for manufacturing a medium-high voltage formation foil, comprising: pre-treating an aluminum foil using a hydrogel pre-treatment solution containing polycations and polyanions; and performing multi-stage formation treatment on the pre-treated aluminum foil using a formation solution. The present disclosure also provides a medium-high voltage formation foil obtained by the method. The present disclosure improves the flexibility of the formation foil while improving the hydration resistance of the formation foil.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of electrode foil, in particular to a manufacturing method of a medium-high voltage formation foil and a medium-high voltage formation foil. BACKGROUND

[0002] In order to improve the conductivity of the electrolyte in the aluminum electrolytic capacitor and reduce the equivalent series resistance (ESR) of the capacitor, the water content of the electrolyte is usually increased, but this will cause the water to react with the oxide film on the surface of the aluminum foil, thereby degrading the performance of the capacitor or even causing the capacitor to fail. To this end, the oxide film is usually treated with phosphate to improve the hydration resistance of the aluminum foil. However, the oxide film treated in this way is too thick and is prone to cause a sudden drop in the capacitor; and the crystalline aluminum oxide has high hardness and great brittleness, which can cause micro-cracks and pinholes on the surface of the aluminum foil, and reduce the ductility and flexibility of the aluminum foil, and even increase the ESR of the capacitor and shorten the service life of the capacitor. SUMMARY

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

[0004] The present disclosure provides a manufacturing method of a medium-high voltage formation foil, comprising the following steps: pretreating an aluminum foil using a hydrogel pretreatment solution containing polycations and polyanions; and performing multi-stage formation treatment on the pretreated aluminum foil using a formation solution.

[0005] According to the manufacturing method of the medium-high voltage formation foil of the present disclosure, the hydrogel pretreatment solution contains polycation compounds with protonated amine groups and polyanion compounds with sulfonic acid groups.

[0006] According to the manufacturing method of the medium-high voltage formation foil of the present disclosure, the polycation compounds with protonated amine groups include at least one of polyethyleneimine and chitosan; and the polyanion compounds with sulfonic acid groups include polystyrene sulfonic acid.

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

[0008] According to the manufacturing method of the medium-high voltage formation foil of the present disclosure, the formation solution contains 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 the medium-high voltage formation foil, the piperidine ionic liquid comprises 1-ethyl-1-methylpiperidine ammonium dihydrogen phosphate, the sulfonic acid ionic liquid comprises polystyrene sulfonic acid, and the thiophene polymer comprises poly 3,4-methylenedioxythiophene. According to the method for manufacturing the medium-high voltage formation foil, the formation solution for at least one stage of formation treatment contains 0.01-0.5 w% glycerol, 0.01-2 w% 1-ethyl-1-methylpiperidine ammonium dihydrogen phosphate, 0.01-2 w% polystyrene sulfonic acid, and 0.01-2 w% poly 3,4-methylenedioxythiophene.

[0010] According to the method for manufacturing the medium-high voltage formation foil, the formation solution for at least one stage of formation treatment contains 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, and 0.01-2 w% chitosan.

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

[0012] According to the method for manufacturing the medium-high voltage formation foil, the method further comprises: performing at least one intermediate treatment on the aluminum foil between the multiple stages of formation treatment.

[0013] According to the method for manufacturing the medium-high voltage formation foil, the method further comprises: performing at least one intermediate treatment on the aluminum foil between the multiple stages of formation treatment.

[0014] According to the method for manufacturing the medium-high voltage formation foil, the aqueous solution containing phosphoric acid comprises 1-5 w% phosphoric acid and 0.01-2 w% ammonium succinate, and the aqueous solution containing organic acid comprises 1-10 w% benzoic acid and 0.01-2 w% sodium alginate.

[0015] According to the method for manufacturing the medium-high voltage formation foil, before the pre-treatment of the aluminum foil with the hydrogel pre-treatment solution containing polycations and polyanions, the method further comprises: performing hydration treatment on the aluminum foil with deionized water.

[0016] According to the method for manufacturing the medium-high voltage formation foil, the method further comprises a heat treatment step performed after the multiple stages of formation treatment.

[0017] According to the method for manufacturing the medium-high voltage formation foil, the heat treatment comprises annealing treatment of the aluminum foil in an inert atmosphere.

[0018] The present disclosure also provides a medium-high voltage formation foil obtained by the above manufacturing method.

[0019] The present disclosure forms a polymeric film with a three-dimensional network structure on the surface of the aluminum foil after etching and the inner wall of the etching hole by pretreating the aluminum foil with a hydrogel pretreatment solution containing a polycation and a polyanion, forming a polyelectrolyte complex through electrostatic interaction, thereby inhibiting ion corrosion and plugging the small holes of the etching foil, thereby preventing the hydrated oxide film from growing excessively; at the same time, the hydration resistance of the formed foil is improved through multi-stage formation treatment. That is, the present disclosure avoids the oxide film of the formed foil being too thick, and also introduces a flexible polymer, thereby greatly improving the flexibility of the formed foil while improving the hydration resistance of the formed foil. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0022] Figure 3 is a micro-morphology image of a medium-high voltage formed foil manufactured according to Example 1 of the present disclosure.

[0023] Figure 4 is a micro-morphology image of a medium-high voltage formed foil manufactured according to Example 2 of the present disclosure.

[0024] Figure 5 is a micro-morphology image of a medium-high voltage formed foil manufactured according to Example 3 of the present disclosure.

[0025] Figure 6 is a micro-morphology image of a medium-high voltage formed foil manufactured according to a comparative example of the present disclosure. DETAILED DESCRIPTION

[0026] In order for those skilled in the art to better understand the technical solutions of the present disclosure, the technical solutions of the present disclosure will be described in detail below with reference to the drawings.

[0027] In the following, example embodiments will be described more fully with reference to the accompanying drawings, in which example embodiments can be embodied in different forms and should not be construed as being limited to the embodiments set forth herein. Rather, the purpose of the embodiments is to explain the present disclosure fully and to provide those skilled in the art with a full understanding of the scope of the present disclosure.

[0028] The embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

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

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” 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 stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded.

[0031] Unless otherwise specified, all terms used herein (including technical and scientific terms) 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 this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0032] This disclosure provides a method for manufacturing medium- and high-voltage electrolytic foil, referring to... Figure 1 This includes the following steps:

[0033] S1. Pretreatment: The aluminum foil is pretreated using a hydrogel pretreatment solution containing polycationic and polyanionic substances.

[0034] S2. Multi-stage formation process: The pre-treated aluminum foil is subjected to a multi-stage formation process using a formation solution.

[0035] The pretreatment utilizes a hydrogel containing polycations and polyanions to form a polyelectrolyte complex through electrostatic interaction, forming a three-dimensional network polymer film on the surface of the etched aluminum foil and the inner wall of the etched holes. This film inhibits ion erosion and blocks the pores of the etched foil, thereby preventing the continued growth of the hydrated oxide film. At the same time, the introduction of flexible polymers greatly reduces the brittleness of the etched foil.

[0036] The hydrogel containing polycations and polyanions includes polycationic compounds with protonated amine groups and polyanionic compounds with sulfonic acid groups.

[0037] The polycationic compound with protonated amine groups includes at least one of polyethyleneimine and chitosan; the polyanionic compound with sulfonic acid groups is polystyrene sulfonic acid. The polycations and polyanions are dispersed in the hydrogel formed by crosslinking 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.

[0038] In some embodiments, the hydrogel pre-treatment solution comprises 1-5 w% polyethyleneimine, 5-10 w% chitosan, 1-10 w% polystyrene sulfonic acid, 2-10 w% ammonium succinate, 1-2 w% glutaraldehyde, 5-10 w% polyvinyl alcohol; the temperature for pre-treating the aluminum foil is 60-90℃, and the time is 30-50 minutes.

[0039] The use of the formation solution in the multi-stage formation process gradually dehydrates the hydrated oxide film to form a crystalline oxide film, and the formation solution contains at least one of a piperidine-based ionic liquid, a sulfonic acid-based ionic liquid, and a thiophene-based polymer. The thiophene-based polymer provides charged ions. The formation solution can also contain an alcohol substance, the hydroxyl group of which is complexed with Al 3+ to delay local excessive oxidation.

[0040] In some embodiments, the piperidine-based ionic liquid includes 1-ethyl-1-methylpiperidine ammonium dihydrogen phosphate, the sulfonic acid-based ionic liquid includes polystyrene sulfonic acid, and the thiophene-based polymer includes poly 3,4-methylenedioxythiophene.

[0041] In some embodiments, the formation solution of at least one stage of the formation process contains 0.01-0.5 w% glycerol, 0.01-2 w% 1-ethyl-1-methylpiperidine ammonium dihydrogen phosphate, 0.01-2 w% polystyrene sulfonic acid, and 0.01-2 w% poly 3,4-methylenedioxythiophene.

[0042] In some embodiments, the formation solution of at least one stage of the formation process contains 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, and 0.01-2 w% chitosan.

[0043] The polyelectrolyte complex in the formation solution is adsorbed on the surface of each layer of the oxide film through intermolecular forces, reducing the damage of the medium to the oxide film. Polystyrene sulfonic acid and poly 3,4-methylenedioxythiophene form a composite conductive layer on the surface of the oxide film due to their unique structural characteristics, with a three-dimensional conductive network structure, and their hydrophilic structure makes the formation solution more easily penetrate into the nanometer pores of the corroded foil, increasing the effective contact area and improving the energy storage density.

[0044] The method for manufacturing the medium-high voltage formation foil according to the present disclosure further comprises one or more intermediate treatments of the aluminum foil between the multi-stage formation treatments. The intermediate treatment step comprises treating the aluminum foil with an aqueous solution containing a phosphorus-containing acid or treating the aluminum foil with an aqueous solution containing an organic acid. The intermediate treatment with the phosphorus-containing acid can generate a dense and high-resistance AlPO4 precipitate, fill in the vacuum and cracks, and reduce the leakage current. The intermediate treatment with the organic acid can form an Al-organic acid-phosphoric acid ternary complex with the organic acid as an auxiliary ligand of the phosphoric acid, thereby enhancing the stability of the oxide film. The phosphorus-containing acid 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 the excess protective layer, purify the surface, and repair the damage to the oxide film.

[0045] In some embodiments, the at least one intermediate treatment of the aluminum foil between the multi-stage formation treatments comprises: a first intermediate treatment of the aluminum foil with an aqueous solution containing a phosphorus-containing acid; and a second intermediate treatment of the aluminum foil with an aqueous solution containing an organic acid.

[0046] In some embodiments, the aqueous solution containing the phosphorus-containing acid contains 1-5 w% phosphoric acid and 0.01-2 w% ammonium succinate; and the aqueous solution containing the organic acid contains 1-10 w% benzoic acid and 0.01-2 w% sodium alginate.

[0047] The method for manufacturing the medium-high voltage formation foil according to the present disclosure further comprises a hydration treatment of the aluminum foil before the pre-treatment. The hydration treatment comprises treating the aluminum foil with deionized water. The hydration treatment can form a layered hydrated oxide film on the surface of the etched foil and the inner wall of the etched hole, with a thickness of about 5 nm, in which the hydroxyl groups are arranged in layers. The hydrated oxide film can increase the dielectric constant and optimize the breakdown voltage.

[0048] The method for manufacturing the medium-high voltage formation foil according to the present disclosure further comprises a heat treatment step after the multi-stage formation treatment. The heat treatment comprises annealing the aluminum foil in an inert atmosphere. The heat treatment can eliminate internal stress of the formation foil, optimize the grain orientation, and improve the ductility.

[0049] According to one embodiment of the present disclosure, with reference to Figure 2 , the method for manufacturing the medium-high voltage formation foil comprises:

[0050] S1, pre-treating the aluminum foil subjected to the hydration treatment with a hydrogel pre-treatment solution containing a polycation and a polyanion

[0051] The aluminum foil subjected to the chemical / electrochemical etching is treated with deionized water during the hydration treatment, and then the aluminum foil subjected to the hydration treatment is placed in a hydrogel pre-treatment solution containing a polycation and a polyanion for treatment at a suitable temperature.

[0052] For example, the water gel pretreatment solution contains polyethyleneimine, chitosan, polystyrene sulfonic acid, ammonium succinate, glutaraldehyde, and polyvinyl alcohol.

[0053] S21, primary anodizing treatment of the pretreated aluminum foil

[0054] The pretreated aluminum foil is placed in an aqueous solution containing glycerol, 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, polystyrene sulfonic acid, and poly 3,4-methylenedioxythiophene, and is treated at an appropriate temperature and voltage.

[0055] S22, secondary anodizing treatment of the aluminum foil subjected to the primary anodizing treatment

[0056] The aluminum foil subjected to the primary anodizing treatment is washed with water and then placed in an aqueous solution containing glycerol, 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, polystyrene sulfonic acid, and poly 3,4-methylenedioxythiophene, and is treated at an appropriate temperature and voltage.

[0057] S3, primary etching treatment of the aluminum foil subjected to the secondary anodizing treatment

[0058] The aluminum foil subjected to the secondary anodizing treatment is washed with water and then placed in an aqueous solution containing phosphoric acid and ammonium succinate, and is treated at an appropriate temperature.

[0059] S23, tertiary anodizing treatment of the aluminum foil subjected to the primary etching treatment

[0060] The aluminum foil subjected to the primary etching treatment is washed with water and then placed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, and chitosan, and is treated at an appropriate temperature and voltage.

[0061] S24, quaternary anodizing treatment of the aluminum foil subjected to the tertiary anodizing treatment

[0062] The aluminum foil subjected to the tertiary anodizing treatment is washed with water and then placed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, and chitosan, and is treated at an appropriate temperature and voltage.

[0063] S4, secondary etching treatment of the aluminum foil subjected to the quaternary anodizing treatment

[0064] The aluminum foil subjected to the quaternary anodizing treatment is washed with water and then placed in an aqueous solution containing benzoic acid and sodium alginate, and is treated at an appropriate temperature.

[0065] S25, quinary anodizing treatment of the aluminum foil subjected to the secondary etching treatment

[0066] The aluminum foil subjected to the secondary etching treatment is washed with water and then placed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, and chitosan, and is treated at an appropriate temperature and voltage.

[0067] S5, heat treatment of the aluminum foil after five-stage formation treatment

[0068] The aluminum foil after five-stage formation treatment is washed with water and then annealed.

[0069] S26, six-stage formation treatment of the aluminum foil after heat treatment

[0070] The aluminum foil after heat treatment is washed with water and then immersed in an aqueous solution containing polyethyleneimine, polystyrene sulfonic acid, 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, chitosan, and treated at an appropriate temperature and voltage.

[0071] S6, post-treatment of the aluminum foil after six-stage formation treatment

[0072] The aluminum foil after six-stage formation treatment is washed with water and then dried.

[0073] According to one embodiment of the present disclosure, the method for manufacturing the medium-high voltage formed foil specifically comprises:

[0074] Hydration treatment:

[0075] The aluminum foil after chemical / electrochemical etching is immersed in deionized water at 90-100°C for 1-5 minutes to remove dust, foil ash and other impurities.

[0076] Pre-treatment:

[0077] The aluminum foil after hydration treatment is placed in an aqueous gel containing 1-5 w% polyethyleneimine, 5-10 w% chitosan, 1-10 w% polystyrene sulfonic acid, 2-10 w% ammonium succinate, 1-2 w% glutaraldehyde, and 5-10 w% polyvinyl alcohol, and treated at a temperature of 60-90°C for 30-50 minutes.

[0078] First-stage formation treatment:

[0079] The aluminum foil after pre-treatment is placed in an aqueous solution containing 0.01-0.5 w% glycerol, 0.01-2 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.01-2 w% polystyrene sulfonic acid, and 0.01-2 w% poly(3,4-methylenedioxythiophene), and treated at a temperature of 40-60°C and a voltage of 90-170V for 10-20 minutes.

[0080] Second-stage formation treatment:

[0081] The aluminum foil after the first-stage chemical conversion treatment is washed with water and then placed in an aqueous solution containing 0.01-0.5 w% glycerol, 0.01-2 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.01-2 w% polystyrene sulfonic acid, and 0.01-2 w% poly 3,4-methylenedioxythiophene, and treated at a temperature of 80-95 °C and a voltage of 150-240 V for 10-20 minutes.

[0082] First intermediate treatment:

[0083] The aluminum foil after the second-stage chemical conversion treatment is washed with water and then placed in an aqueous solution containing 1-5 w% phosphoric acid and 0.01-2 w% ammonium succinate, and treated at a temperature of 30-45 °C for 2-10 minutes.

[0084] Third-stage chemical conversion treatment:

[0085] The aluminum foil after the first intermediate treatment is washed with water and then placed in an aqueous solution containing 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, and 0.01-2 w% chitosan, and treated at a temperature of 40-60 °C and a voltage of 250-340 V for 10-20 minutes.

[0086] Fourth-stage chemical conversion treatment:

[0087] The aluminum foil after the third-stage chemical conversion treatment is washed with water and then placed in an aqueous solution containing 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, and 0.01-2 w% chitosan, and treated at a temperature of 80-95 °C and a voltage of 350-440 V for 10-20 minutes.

[0088] Second intermediate treatment:

[0089] The aluminum foil after the fourth-stage chemical conversion treatment is washed with water and then placed in an aqueous solution containing 1-10 w% benzoic acid and 0.01-2 w% sodium alginate, and treated at a temperature of 30-45 °C for 2-10 minutes.

[0090] Fifth-stage chemical conversion treatment:

[0091] The aluminum foil after the second intermediate treatment is washed with water and then placed in an aqueous solution containing 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, 0.01-2 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, and 0.01-2 w% chitosan, and treated at a temperature of 40-60 °C and a voltage of 450-540 V for 10-20 minutes.

[0092] Heat treatment:

[0093] The aluminum foil after the fifth-stage chemical conversion treatment is washed with water and then annealed at a temperature of 350-550 °C for 2-10 minutes in a nitrogen atmosphere.

[0094] Sixth stage formation treatment:

[0095] The heat-treated aluminum foil is washed with water and then placed in an aqueous solution containing 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, 0.01-2 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, and 0.01-2 w% chitosan, and treated at a temperature of 80-95°C and a voltage of 550-660V for 10-20 minutes.

[0096] Post-treatment:

[0097] The aluminum foil after the sixth stage formation treatment is washed with water and then dried with hot air at 60-120°C for 5-10 minutes to ensure no water remains.

[0098] The present disclosure also provides a medium-high voltage formation foil obtained according to the above manufacturing method.

[0099] The surface micro-morphology of the medium-high voltage formation foil obtained according to the manufacturing method of the present disclosure is a uniform and dense ball-like oxide film with a loose, porous, and fibrous nanostructure, which has the effects of buffering, liquid storage, self-healing, heat dissipation, etc. in capacitors, and its electrostatic capacity, test voltage resistance, voltage rising time, bending strength, tensile strength, and leakage current as a formation foil are all superior to those of formation foils prepared by traditional processes.

[0100] In order for those skilled in the art to more clearly understand the technical solutions of the present disclosure, the technical solutions of the present disclosure are described in detail below through specific examples.

[0101] Example 1

[0102] Hydration treatment: The aluminum foil after chemical / electrochemical etching is immersed in 95°C deionized water for 5 minutes for hydration treatment.

[0103] Pre-treatment: The aluminum foil after hydration treatment is placed in an aqueous gel containing 1 w% polyethyleneimine, 5 w% chitosan, 1 w% polystyrene sulfonic acid, 2 w% ammonium succinate, 1 w% glutaraldehyde, and 5 w% polyvinyl alcohol, and treated at 60°C for 30 minutes.

[0104] First stage formation treatment: The aluminum foil after pre-treatment is placed in an aqueous solution containing 0.01 w% glycerol, 0.015 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.015 w% polystyrene sulfonic acid, and 0.015 w% poly(3,4-methylenedioxythiophene), and treated at 45°C and a voltage of 110V for 10 minutes.

[0105] Secondary chemical conversion treatment: The aluminum foil subjected to the primary chemical conversion treatment was washed with water and then placed in an aqueous solution containing 0.01 w% glycerol, 0.015 w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, 0.015 w% polystyrene sulfonic acid, and 0.015 w% poly(3,4- methylene dioxythiophene) at 85°C for 20 minutes at a voltage of 240 V.

[0106] First intermediate treatment: The aluminum foil subjected to the secondary chemical conversion treatment was washed with water and then placed in an aqueous solution containing 1 w% phosphoric acid and 0.01 w% ammonium succinate at 35°C for 10 minutes.

[0107] Third chemical conversion treatment: The aluminum foil subjected to the first intermediate treatment was washed with water and then placed in an aqueous solution containing 0.015 w% polyethyleneimine, 0.03 w% polystyrene sulfonic acid, and 0.015 w% chitosan at 45°C for 15 minutes at a voltage of 340 V.

[0108] Fourth chemical conversion treatment: The aluminum foil subjected to the third chemical conversion treatment was washed with water and then placed in an aqueous solution containing 0.015 w% polyethyleneimine, 0.03 w% polystyrene sulfonic acid, and 0.015 w% chitosan at 85°C for 20 minutes at a voltage of 440 V.

[0109] Second intermediate treatment: The aluminum foil subjected to the fourth chemical conversion treatment was washed with water and then placed in an aqueous solution containing 1 w% benzoic acid and 0.01 w% sodium alginate at 35°C for 5 minutes.

[0110] Fifth chemical conversion treatment: The aluminum foil subjected to the second intermediate treatment was washed with water and then placed in an aqueous solution containing 0.015 w% polyethyleneimine, 0.03 w% polystyrene sulfonic acid, 0.03 w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.015 w% chitosan at 45°C for 15 minutes at a voltage of 540 V.

[0111] Heat treatment: The aluminum foil subjected to the fifth chemical conversion treatment was washed with water and then annealed at 350°C for 2 minutes in a nitrogen atmosphere.

[0112] Sixth chemical conversion treatment: The aluminum foil subjected to the heat treatment was washed with water and then placed in an aqueous solution containing 0.015 w% polyethyleneimine, 0.03 w% polystyrene sulfonic acid, 0.03 w% 1-ethyl-1-methylpiperidinium dihydrogen phosphate, and 0.015 w% chitosan at 85°C for 20 minutes at a voltage of 650 V.

[0113] Post-treatment: The aluminum foil subjected to the sixth chemical conversion treatment was washed with water and then dried at 100°C for 10 minutes using hot air.

[0114] Example 2

[0115] Hydration treatment: The aluminum foil subjected to the chemical / electrochemical etching was immersed in deionized water at 96°C for 5 minutes.

[0116] Pre-treatment: The aluminum foil after hydration treatment was put into the water gel of 3w% polyethyleneimine, 5w% chitosan, 8w% polystyrene sulfonic acid, 6w% ammonium succinate, 1w% glutaraldehyde, 5w% polyvinyl alcohol, and treated at 60°C for 40 minutes.

[0117] First-stage anodization treatment: The aluminum foil after pre-treatment was put into the water solution of 0.1w% glycerol, 0.1w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.1w% polystyrene sulfonic acid, 0.1w% poly-3,4-methylenedioxythiophene, and treated at 45°C, voltage 140V, time 15 minutes.

[0118] Second-stage anodization treatment: The aluminum foil after first-stage anodization treatment was washed with water and then put into the water solution of 0.1w% glycerol, 0.1w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.1w% polystyrene sulfonic acid, 0.1w% poly-3,4-methylenedioxythiophene, and treated at 85°C, voltage 240V, time 20 minutes.

[0119] First intermediate treatment: The aluminum foil after second-stage anodization treatment was washed with water and then put into the water solution of 2w% phosphoric acid, 0.1w% ammonium succinate, and treated at 35°C for 10 minutes.

[0120] Third-stage anodization treatment: The aluminum foil after first intermediate treatment was washed with water and then put into the water solution of 0.1w% polyethyleneimine, 0.2w% polystyrene sulfonic acid, 0.1w% chitosan, and treated at 45°C, voltage 340V, time 15 minutes.

[0121] Fourth-stage anodization treatment: The aluminum foil after third-stage anodization treatment was washed with water and then put into the water solution of 0.1w% polyethyleneimine, 0.2w% polystyrene sulfonic acid, 0.1w% chitosan, and treated at 85°C, voltage 440V, time 20 minutes.

[0122] Second intermediate treatment: The aluminum foil after fourth-stage anodization treatment was washed with water and then put into the water solution of 5w% benzoic acid, 0.1w% sodium alginate, and treated at 35°C for 10 minutes.

[0123] Fifth-stage anodization treatment: The aluminum foil after second intermediate treatment was washed with water and then put into the water solution of 0.1w% polyethyleneimine, 0.3w% polystyrene sulfonic acid, 0.3w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.15w% chitosan, and treated at 45°C, voltage 540V, time 15 minutes.

[0124] Heat treatment: The aluminum foil after fifth-stage anodization treatment was washed with water and then annealed at 450°C for 5 minutes in a nitrogen atmosphere.

[0125] Sixth stage formation treatment: The heat treated aluminum foil was washed with water and then placed in an aqueous solution containing 0.1 w% polyethyleneimine, 0.3 w% polystyrene sulfonic acid, 0.3 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.15 w% chitosan, 85 °C, voltage 650 V, time 20 minutes.

[0126] Post-treatment: The aluminum foil after the sixth stage formation treatment was washed with water and then dried with hot air at 100 °C for 10 minutes to ensure no water remained.

[0127] Example 3

[0128] Hydration treatment: The aluminum foil after chemical / electrochemical etching was immersed in deionized water at 96 °C for 5 minutes for hydration treatment.

[0129] Pre-treatment: The aluminum foil after hydration treatment was placed in an aqueous gel containing 5 w% polyethyleneimine, 10 w% chitosan, 10 w% polystyrene sulfonic acid, 5 w% ammonium succinate, 2 w% glutaraldehyde, 10 w% polyvinyl alcohol, 80 °C, time 50 minutes.

[0130] First stage formation treatment: The aluminum foil after pre-treatment was placed in an aqueous solution containing 0.5 w% glycerol, 1.5 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 1.5 w% polystyrene sulfonic acid, 1.5 w% poly 3,4-methylenedioxythiophene, 60 °C, voltage 110 V, time 15 minutes.

[0131] Second stage formation treatment: The aluminum foil after the first stage formation treatment was washed with water and then placed in an aqueous solution containing 0.5 w% glycerol, 1.5 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 1.5 w% polystyrene sulfonic acid, 1.5 w% poly 3,4-methylenedioxythiophene, 90 °C, voltage 240 V, time 20 minutes.

[0132] First intermediate treatment: The aluminum foil after the second stage formation treatment was washed with water and then placed in an aqueous solution containing 5 w% phosphoric acid, 2% ammonium succinate, 35 °C, time 10 minutes.

[0133] Third stage formation treatment: The aluminum foil after the first intermediate treatment was washed with water and then placed in an aqueous solution containing 1.5 w% polyethyleneimine, 3 w% polystyrene sulfonic acid, 1.5 w% chitosan, 60 °C, voltage 340 V, time 15 minutes.

[0134] Fourth stage formation treatment: The aluminum foil after the third stage formation treatment was washed with water and then placed in an aqueous solution containing 1.5 w% polyethyleneimine, 3 w% polystyrene sulfonic acid, 1.5 w% chitosan, 95 °C, voltage 440 V, time 20 minutes.

[0135] Second intermediate treatment: The aluminum foil after the fourth stage of chemical conversion treatment was washed with water and then placed in a 10w% benzoic acid and 2w% sodium alginate aqueous solution at 45°C for 10 minutes.

[0136] Fifth stage of chemical conversion treatment: The aluminum foil after the second intermediate treatment was washed with water and then placed in a 1.5w% polyethyleneimine, 3w% polystyrene sulfonic acid, 3w% 1-ethyl-1-methylpiperidine ammonium dihydrogen phosphate, and 1.5w% chitosan aqueous solution at 60°C, with a voltage of 540V for 20 minutes.

[0137] Heat treatment: The aluminum foil after the fifth stage of chemical conversion treatment was washed with water and then annealed at 550°C for 5 minutes in a nitrogen atmosphere.

[0138] Sixth stage of chemical conversion treatment: The aluminum foil after the heat treatment was washed with water and then placed in a 1.5w% polyethyleneimine, 3w% polystyrene sulfonic acid, 3w% 1-ethyl-1-methylpiperidine ammonium dihydrogen phosphate, and 1.5w% chitosan aqueous solution at 95°C, with a voltage of 660V for 20 minutes.

[0139] Post-treatment: The aluminum foil after the sixth stage of chemical conversion treatment was washed with water and then dried with hot air at 100°C for 10 minutes.

[0140] Comparative Example 1

[0141] Hydration treatment: The aluminum foil after chemical / electrochemical etching was immersed in deionized water at 96°C for 5 minutes for hydration treatment.

[0142] First stage of chemical conversion treatment: The aluminum foil after the hydration treatment was placed in a 1w% boric acid, 0.02w% citric acid, 1.5w% polystyrene sulfonic acid, and 0.1w% ammonium pentaborate aqueous solution at 70°C, with a voltage of 200V for 15 minutes.

[0143] Second stage of chemical conversion treatment: The aluminum foil after the first stage of chemical conversion treatment was washed with water and then placed in a 1w% boric acid, 0.02w% citric acid, 1.5w% polystyrene sulfonic acid, and 0.1w% ammonium pentaborate aqueous solution at 80°C, with a voltage of 400V for 20 minutes.

[0144] Intermediate treatment: The aluminum foil after the second stage of chemical conversion treatment was washed with water and then placed in a 2w% phosphoric acid and 0.2% benzoic acid aqueous solution at 60°C for 2 minutes.

[0145] Third stage of chemical conversion treatment: The aluminum foil after the intermediate treatment was washed with water and then placed in a 2w% boric acid aqueous solution at 80°C, with a voltage of 550V for 15 minutes.

[0146] Fourth stage of chemical conversion treatment: The aluminum foil after the third stage of chemical conversion treatment was washed with water and then placed in a 2w% boric acid aqueous solution at 85°C, with a voltage of 660V for 20 minutes.

[0147] Heat treatment: The aluminum foil after the fourth formation treatment was washed with water and then annealed at 550℃ for 5 minutes in a nitrogen atmosphere.

[0148] Post-treatment: The aluminum foil after the heat treatment was washed with water and then placed in a 2w% phosphoric acid and 1w% boric acid aqueous solution at 60℃ for 2 minutes.

[0149] Drying: The aluminum foil after the post-treatment was washed with water and then hot air dried at 100℃ for 10 minutes.

[0150] The formed foils obtained in Examples 1-3 and Comparative Example 1 were used as formed foils to test the electrical and mechanical properties, and the results are shown in Table 1.

[0151] Table 1 Test results of Examples 1-3 and Comparative Example 1

[0152]

[0153] As can be seen from the table, the static capacity, test voltage resistance, voltage rise time, bending strength, tensile strength, and leakage current of the formed foil prepared by the formation method of the present disclosure are all superior to those of the formed foil prepared by the conventional process. The increase in bending strength and tensile strength indicates that the ductility of the formed foil prepared by the present disclosure is effectively improved.

[0154] Figure 3 、 Figure 4 、 Figure 5 are micro-morphology images of Examples 1-3, respectively, Figure 6 is a micro-morphology image of Comparative Example 1. As can be seen from the figure, the micro-morphology of Comparative Example 1 has an excessive formed oxide film that blocks some of the etching holes, which will reduce the static capacity of the formed foil. Moreover, the excessively thick sheet-shaped oxide film will cause micro-cracks to form during the winding of the formed foil, which will directly affect the performance of the capacitor. The micro-morphology of the formed foil prepared by the present disclosure is a uniform and dense ball-shaped oxide film, which has a loose, porous, and fibrous nanostructure. In a capacitor, it has the functions of buffering, liquid storage, self-healing, and heat dissipation. Therefore, the comprehensive performance of the formed foil prepared by the present disclosure is superior to that of the formed foil prepared by the conventional formation method.

[0155] Example embodiments have been disclosed herein and, although the use of specific terms is exemplified throughout this specification, they are used in an illustrative sense and should not be construed as limiting. In some instances, certain features, characteristics, and / or elements of the described embodiments can be used individually, in combination, or in a combination with features, characteristics, and / or elements described in association with other embodiments, unless explicitly stated otherwise. As such, one of ordinary skill in the art will appreciate that changes can be made in the form and details of the disclosed embodiments without departing from the scope of the present disclosure as expressed by the appended claims.

Claims

1. A method for manufacturing a medium-high voltage formation foil, comprising: pre-treating an aluminum foil using a hydrogel pre-treatment solution containing a polycation and a polyanion; carrying out multi-stage formation treatment on the pre-treated aluminum foil using a formation solution; wherein the hydrogel pre-treatment solution contains a polycation compound with protonated amine groups and a polyanion compound with sulfonic acid groups.

2. The method of manufacturing a middle-high voltage formation foil according to claim 1, wherein, The polycation compound with protonated amine groups comprises at least one of polyethyleneimine and chitosan; and the polyanion compound with sulfonic acid groups comprises polystyrene sulfonic acid.

3. The method of manufacturing a middle high voltage formation foil according to claim 1 or 2, wherein, The hydrogel pre-treatment solution contains 1-5 w% polyethyleneimine, 5-10 w% chitosan, 1-10 w% polystyrene sulfonic acid, 2-10 w% ammonium succinate, 1-2 w% glutaraldehyde, and 5-10 w% polyvinyl alcohol; the pre-treatment temperature of the aluminum foil is 60-90℃, and the pre-treatment time is 30-50 minutes.

4. The method of manufacturing a middle-high voltage formation foil according to claim 1 or 2, wherein, The formation solution contains at least one of a piperidine-based ionic liquid, a sulfonic acid-based ionic liquid, and a thiophene-based polymer.

5. The method of manufacturing a middle high voltage formation foil according to claim 4, wherein, The piperidine-based ionic liquid comprises 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, the sulfonic acid-based ionic liquid comprises polystyrene sulfonic acid, and the thiophene-based polymer comprises poly-3,4-methylenedioxythiophene.

6. The method of manufacturing a middle high voltage formation foil according to claim 5, wherein, The formation solution for at least one stage of formation treatment contains 0.01-0.5 w% glycerol, 0.01-2 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, 0.01-2 w% polystyrene sulfonic acid, and 0.01-2 w% poly-3,4-methylenedioxythiophene.

7. The method of manufacturing a middle high voltage formation foil according to claim 5, wherein, The formation solution for at least one stage of formation treatment contains 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, and 0.01-2 w% chitosan.

8. The method of manufacturing a middle high voltage formation foil according to claim 5, wherein, The formation solution for at least one stage of formation treatment contains 0.01-2 w% polyethyleneimine, 0.01-4 w% polystyrene sulfonic acid, 0.01-2 w% 1-ethyl-1-methylpiperidine dihydrogen ammonium phosphate, and 0.01-2 w% chitosan.

9. The method of manufacturing a middle high voltage formation foil according to claim 1 or 2, wherein, Further comprising: carrying out at least one intermediate treatment on the aluminum foil between the multi-stage formation treatment.

10. The method of manufacturing a middle high voltage formation foil according to claim 9, wherein, carrying out at least one intermediate treatment on the aluminum foil between the multi-stage formation treatment, comprising: carrying out a first intermediate treatment on the aluminum foil using an aqueous solution containing a phosphoric acid-based substance; carrying out a second intermediate treatment on the aluminum foil using an aqueous solution containing an organic acid.

11. The method of manufacturing a middle high voltage formation foil according to claim 10, wherein, The aqueous solution containing the phosphoric acid-based substance contains 1-5 w% phosphoric acid and 0.01-2 w% ammonium succinate; and the aqueous solution containing the organic acid contains 1-10 w% benzoic acid and 0.01-2 w% sodium alginate.

12. The method of manufacturing a middle high voltage formation foil according to claim 1 or 2, wherein, Further comprising, before pre-treating the aluminum foil using the hydrogel pre-treatment solution containing the polycation and the polyanion: carrying out hydration treatment on the aluminum foil using deionized water. 13.A medium-high voltage formation foil obtained by the method for manufacturing a medium-high voltage formation foil according to any one of claims 1 to 12.

Images