A method for manufacturing an aluminum electrolytic capacitor anode foil and an aluminum electrolytic capacitor

Abstract

The present disclosure relates to a preparation method of an aluminum electrolytic capacitor anode foil and an aluminum electrolytic capacitor, and relates to the technical field of electrolytic capacitors. The method comprises the following steps: preparing a first mixed solution and a second mixed solution, the first mixed solution being prepared by mixing an organic solvent and a binder, and the second mixed solution being prepared by mixing deionized water and an aqueous resin; preparing a mixed slurry, the mixed slurry comprising aluminum powder and a third mixed solution, the third mixed solution being prepared by mixing the first mixed solution, the second mixed solution and an additive; providing an aluminum foil substrate and coating the mixed slurry on the surface of the aluminum foil substrate; then, performing directional drying treatment on the aluminum foil with the slurry film layer to form an aluminum foil blank; performing vibration treatment on the aluminum foil blank, and performing drying treatment on the aluminum foil blank after the vibration treatment to form an initial anode foil; then, performing sintering treatment on the initial anode foil to form a target anode foil. The method improves the bending performance of the target anode foil.

Description

Technical Field

[0001] This disclosure relates to the field of electrolytic capacitor technology, and more specifically, to a method for preparing an anode foil for an aluminum electrolytic capacitor and an aluminum electrolytic capacitor. Background Technology

[0002] Aluminum electrolytic capacitors are widely used in various fields such as electronic communications, automotive industry, optoelectronic products, and high-speed rail. Meanwhile, in the manufacturing process of aluminum electrolytic capacitors, the anode foil is a key raw material that determines the overall performance of the capacitor. As aluminum electrolytic capacitors further develop towards higher capacitance, miniaturization, and greener designs, the requirements for the bending performance of the anode foil are becoming increasingly stringent.

[0003] Currently, the bending performance of anode foil can be improved in several ways: The first method is to subject the aluminum foil to oblique stress when it passes through an inclined roller set in a conveying trough or a roller with balls on its circumferential surface that can rotate around their own center, thus obtaining an anode foil with multi-directional cracks on its surface; the second method is to use a shaped roller to roll-press the coated surface of the aluminum foil substrate after drying to obtain the anode foil; the third method is to use an anilox roller to heat-press the coated surface of the aluminum foil substrate after drying to obtain the anode foil; at the same time, the anode foil obtained by the above methods can generate irregular multi-directional cracks on the surface of the anode foil, thereby achieving the purpose of improving the bending performance of the anode foil in both the transverse and longitudinal directions.

[0004] However, the above-described processing methods all aim to improve bending performance by applying stress or strain to the foil with rollers to induce micro-cracks in the foil. During this process, the aluminum powder layer on the surface of the foil needs to come into contact with the rollers, which can easily lead to scratches and powder loss on the foil surface, causing the foil to stick together after sintering. This results in the inability to produce an anode foil with a complete surface and good bending performance.

[0005] It should be noted that the information in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this disclosure is to provide a method for preparing an anode foil for an aluminum electrolytic capacitor and an aluminum electrolytic capacitor, thereby overcoming, to at least a certain extent, the problem of being unable to produce an anode foil with a complete surface and good bending performance due to limitations and defects in related technologies.

[0007] According to one aspect of this disclosure, a method for preparing an anode foil for an aluminum electrolytic capacitor is provided, comprising: step S101, preparing a first mixed solution and a second mixed solution, wherein the first mixed solution is prepared by mixing an organic solvent and a binder, and the second mixed solution is prepared by mixing deionized water and an aqueous resin; step S102, preparing a mixed slurry, wherein the mixed slurry comprises aluminum powder and a third mixed solution, wherein the third mixed solution is prepared by mixing the first mixed solution, the second mixed solution, and an additive; step S103, providing an aluminum foil substrate and coating the surface of the aluminum foil substrate with the mixed slurry; then, performing a directional drying treatment on the aluminum foil having the slurry film layer to form an aluminum foil blank; step S104, performing a vibration treatment on the aluminum foil blank and a drying treatment on the vibrated aluminum foil blank to form an initial anode foil; then, performing a sintering treatment on the initial anode foil to form a target anode foil.

[0008] In one exemplary embodiment of this disclosure, in the first mixed solution, the mass ratio between the organic solvent and the binder is 100:(1~10); the organic solvent includes terpineol and / or diethylene glycol butyl ether acetate; the binder is ethyl cellulose.

[0009] In one exemplary embodiment of this disclosure, the mass ratio of deionized water to aqueous resin in the second mixed solution is 100:(1~10); the aqueous resin includes one or more of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose; the molecular weight of the polyethylene glycol is 2000~20000.

[0010] In an exemplary embodiment of this disclosure, in the mixed slurry, the mass ratio of the aluminum powder to the third mixed solution is 100:(40~150); in the third mixed solution, the mass ratio of the first mixed solution, the second mixed solution, and the additive is 100:(10~100):(1~10); the additive includes a first additive and a second additive, the first additive being a leveling agent, and the second additive including one or more of a defoamer, a dispersant, and a coupling agent; the defoamer is an organosilicon defoamer or a polyether defoamer, the dispersant is diethanolamine or triethanolamine, the coupling agent is a silane coupling agent, and the leveling agent is an acrylate leveling agent.

[0011] In an exemplary embodiment of this disclosure, the aluminum foil substrate has a thickness of 20 μm to 60 μm and has an upper surface and a lower surface disposed opposite to each other. The aluminum foil blank is obtained by: double-sided coating the aluminum foil substrate with the mixed slurry to form a slurry film layer of the same thickness on the upper surface and the lower surface of the aluminum foil substrate; and directional drying treatment of the aluminum foil substrate having the slurry film layer to obtain the aluminum foil blank; wherein the thickness of the slurry film layer in the aluminum foil blank is 50 μm to 60 μm.

[0012] In an exemplary embodiment of this disclosure, the directional drying process of the aluminum foil substrate having the slurry film layer is achieved as follows: 20 to 100 sets of heating devices are arranged above and below the aluminum foil substrate having the slurry film layer; wherein each set of heating devices includes two heating elements, and the transverse axial directions of the two heating elements in the same set of heating devices form angles of 30° to 60° and 120° to 150° with the length direction of the aluminum foil substrate having the slurry film layer, respectively; during the directional drying process, the temperature of the heating elements is set to 200°C to 300°C; the interval between each heating element is cooled by room temperature air on the aluminum foil substrate having the slurry film layer, and the speed at which the aluminum foil substrate having the slurry film layer is conveyed along the length direction is 1 m / min to 50 m / min; the heating elements include heating tubes and / or hot air nozzles.

[0013] In an exemplary embodiment of this disclosure, the initial anode foil is determined by immersing the aluminum foil blank in an immersion solution, then vibrating the aluminum foil blank in the immersion solution using sound waves as a vibration source; and then drying the vibrated aluminum foil blank at a drying temperature of 100°C to 200°C to obtain the initial anode foil.

[0014] In one exemplary embodiment of this disclosure, the soaking solution includes one or more of polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, ethylene glycol, and propylene glycol; the sound wave includes ultrasound or megasonic waves.

[0015] In an exemplary embodiment of this disclosure, the target anode foil is obtained by heating the initial anode foil from room temperature to 600°C to 650°C at a heating rate of 0.1°C / min to 20°C / min in a nitrogen, argon, or vacuum atmosphere, and holding it at that temperature for 4 to 12 hours; after the holding period, the initial anode foil is cooled in the furnace, and then subjected to a boiling treatment to form an intermediate anode foil; finally, the intermediate anode foil is subjected to a formation treatment to form an oxide layer on the intermediate anode foil to obtain the target anode foil; wherein, the boiling treatment is achieved by boiling the cooled initial anode foil in deionized water at 100°C for 5 to 15 minutes; and the formation voltage used in the formation treatment is 200V to 700V.

[0016] According to one aspect of this disclosure, an aluminum electrolytic capacitor is provided, wherein the aluminum electrolytic capacitor comprises a target anode foil prepared by the method for preparing the anode foil of the aluminum electrolytic capacitor as described in any one of the preceding claims.

[0017] This disclosure provides a method for preparing an anode foil for an aluminum electrolytic capacitor. On one hand, deionized water, aqueous resin, and a leveling agent are added to a mixed slurry. Based on this, the mixed slurry is coated onto the surface of an aluminum foil substrate and then directionally dried to obtain an aluminum foil blank. Further, the aluminum foil blank is subjected to vibration treatment to obtain an initial anode foil, resulting in irregular multidirectional microcracks on the surface of the initial anode foil, thereby improving the bending performance of the target anode foil after subsequent formation treatment. On the other hand, because deionized water is added to the mixed slurry, a hydrated alumina film can be formed on the surface of the slurry film during the drying process. This hydrated alumina film can form a gap between adjacent aluminum foil blanks. Based on this, adhesion between aluminum foil blanks can be avoided during subsequent sintering, thus solving the problem in the prior art of failing to produce an anode foil with a complete surface and good bending performance.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0020] Figure 1The flowchart schematically illustrates a method for preparing an anode foil for an aluminum electrolytic capacitor according to an exemplary embodiment of the present disclosure.

[0021] Figure 2 The diagram illustrates a light microscope image of an anode foil obtained according to an exemplary embodiment of the present disclosure, based on the preparation method provided in Comparative Example 1.

[0022] Figure 3 The diagram illustrates a light microscope image of an anode foil obtained according to an exemplary embodiment of the present disclosure, based on the preparation method provided in Comparative Example 2.

[0023] Figure 4(a) schematically illustrates an optical mirror of an anode foil obtained according to an exemplary embodiment of the present disclosure, based on the preparation method provided in Example 1. Figure 1 .

[0024] Figure 4(b) schematically shows an optical mirror of an anode foil obtained according to an exemplary embodiment of the present disclosure based on the preparation method provided in Example 1. Figure 2 . Detailed Implementation

[0025] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of the specific details omitted, or other methods, components, apparatus, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0026] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0027] This disclosure first provides a method for preparing the anode foil of an aluminum electrolytic capacitor. Specifically, refer to... Figure 1As shown, the method for preparing the anode foil of the aluminum electrolytic capacitor may include the following steps: Step S101: Prepare a first mixed solution and a second mixed solution. The first mixed solution is prepared by mixing an organic solvent and a binder, and the second mixed solution is prepared by mixing deionized water and a water-based resin. Step S102: Prepare a mixed slurry, the mixed slurry comprising aluminum powder and a third mixed solution, the third mixed solution being a mixture of a first mixed solution, a second mixed solution and additives; Step S103: Provide an aluminum foil substrate and coat the surface of the aluminum foil substrate with the mixed slurry; then, perform directional drying treatment on the aluminum foil having the slurry film layer to form an aluminum foil blank; In step S104, the aluminum foil blank is subjected to vibration treatment, and the aluminum foil blank after vibration treatment is dried to form an initial anode foil; then, the initial anode foil is sintered to form a target anode foil.

[0028] In the above-described method for preparing the anode foil of an aluminum electrolytic capacitor, on the one hand, deionized water, water-based resin, and leveling agent are added to the mixed slurry; based on this, the mixed slurry is coated on the surface of an aluminum foil substrate and then directionally dried to obtain an aluminum foil blank; further, the aluminum foil blank is subjected to vibration treatment to obtain an initial anode foil, so that the surface of the obtained initial anode foil has irregular multidirectional microcracks (that is, the surface of the obtained anode foil is smooth, rather than an anode foil with an orange peel texture), thereby improving the bending performance of the target anode foil after subsequent formation treatment; on the other hand, since deionized water is added to the mixed slurry, a hydrated alumina film can be formed on the surface of the slurry film layer during the drying process, and this hydrated alumina film layer can form a gap between adjacent aluminum foil blanks; based on this, adhesion between aluminum foil blanks can be avoided during subsequent sintering, thereby solving the problem in the prior art that it is impossible to produce an anode foil with a complete surface and good bending performance.

[0029] In one example embodiment, the reason for adding water-based resin and leveling agent is to achieve the following: (1) Like binder (ethyl cellulose), water-based resin is also a type of binder, but the two have different properties such as flexibility, coefficient of thermal expansion, and decomposition temperature; on this basis, compared with the slurry without water-based resin, the slurry with water-based resin contains two types of binders; during the sintering process, since the decomposition temperatures of water-based resin and ethyl cellulose are different, this will result in the sintering stress in the aluminum foil blank coated with the slurry with water-based resin being greater than the sintering stress in the aluminum foil blank coated with the slurry without water-based resin, that is, adding water-based resin is more conducive to the formation of microcracks during the sintering process. (2) Compared with the method of coating the aluminum foil substrate with a mixed slurry without water-based resin and leveling agent, and then drying it to form an orange peel texture to achieve uneven internal stress in the film layer, the method of coating the aluminum foil substrate with a slurry containing water-based resin and leveling agent can form a smooth surface in the aluminum foil blank during the directional drying process, and can also form uneven internal stress in the aluminum foil blank due to the uneven composition of micro-regions.

[0030] In one example embodiment, since the water-based resin and ethyl cellulose have different properties such as flexibility, coefficient of thermal expansion, and decomposition temperature, and ethyl cellulose is insoluble in water, after the water-based resin is added, a film layer with uneven micro-region composition will naturally form during the directional drying process, thereby forming unevenly distributed internal stress in the slurry film layer. Therefore, directional heating and drying can be carried out directly without drying the slurry film layer to obtain the aluminum foil blank.

[0031] The following will provide a detailed explanation and description of the method for preparing the anode foil of the aluminum electrolytic capacitor as described in the exemplary embodiments of this disclosure, in conjunction with the accompanying drawings.

[0032] In step S101, a first mixed solution and a second mixed solution are prepared. The first mixed solution is prepared by mixing an organic solvent and a binder, and the second mixed solution is prepared by mixing deionized water and a water-based resin.

[0033] In this embodiment of the present disclosure, the mass ratio between the organic solvent and the binder in the first mixed solution is 100:(1~10); for example, the mass ratio can be 100:1, 100:3, 100:5, 100:7 or 100:10, etc., and this example does not impose any special limitations on this; meanwhile, the organic solvent described herein may include, but is not limited to, terpineol and diethylene glycol butyl ether acetate, etc., and the binder described herein may be ethyl cellulose.

[0034] In this embodiment of the present disclosure, the mass ratio between deionized water and aqueous resin in the second mixed solution is 100:(1~10); for example, the mass ratio can be 100:1, 100:2, 100:4, 100:6, 100:8 or 100:10, etc., and this example does not impose any special limitations on this; meanwhile, the aqueous resin described herein may include, but is not limited to, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose; meanwhile, the molecular weight of the polyethylene glycol described herein may be 2000~20000.

[0035] In step S102, a mixed slurry is prepared, the mixed slurry comprising aluminum powder and a third mixed solution, the third mixed solution being a mixture of a first mixed solution, a second mixed solution and additives.

[0036] In this embodiment of the disclosure, the mixed slurry may include aluminum powder and a third mixed solution; at the same time, in the obtained mixed slurry, the mass ratio of aluminum powder to the third mixed solution may be 100:(40~150); for example, the mass ratio between the two may be 100:40, 100:60, 100:80, 100:100, 100:120 or 100:150, etc., and this example does not impose any special restrictions on this; furthermore, limiting the mass ratio between aluminum powder and the third mixed solution to the above range can make the slurry viscosity moderate, which is beneficial to the formation quality of the subsequent aluminum foil blank.

[0037] In this embodiment of the disclosure, the aluminum particles in the aluminum powder can be spherical or ellipsoidal particles, and the particle size of the aluminum powder is 0.5μm to 5μm. For example, the particle size of the aluminum powder can be 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, or 5μm, etc. This example does not impose any special limitations on this. Furthermore, in the process of preparing aluminum powder, there can be multiple aluminum powders with different particle sizes, or aluminum powders with the same or approximately the same particle size. This example does not impose any special limitations on this. Moreover, the quality purity of the aluminum powder used here is 99.99% to control the impurity content.

[0038] In this embodiment of the disclosure, in the third mixed solution described above, the mass ratio of the first mixed solution, the second mixed solution, and the additive can be 100:(10~100):(1~10); for example, the mass ratio of the three can be 100:10:1, 100:10:3, 100:30:5, 100:50:7, or 100:100:10, etc., and this example does not impose any special limitations on this; at the same time, the mass ratio between the components in the third mixed solution can be selected or adaptively adjusted according to the specific type and function of the components.

[0039] In this embodiment, the additives may include a first additive and a second additive. The first additive is a leveling agent, and the second additive includes, but is not limited to, defoamers, dispersants, and coupling agents. The defoamer may be a silicone defoamer or a polyether defoamer, the dispersant may be diethanolamine or triethanolamine, the coupling agent may be a silane coupling agent, and the leveling agent may be an acrylate leveling agent. Furthermore, by controlling the type and mass ratio of each component in the mixed slurry, the slurry can be characterized by low evaporation rate, easy storage, and moderate viscosity at room temperature (20-25°C). Based on this, among the selected additives, the solvent is easily volatile during drying, and the binder, aqueous resin, and additives leave little or no residue during the sintering process, thereby reducing the impurity content in the prepared target anode foil.

[0040] In step S103, an aluminum foil substrate is provided, and the mixed slurry is coated on the surface of the aluminum foil substrate; then, the aluminum foil with the slurry film layer is subjected to directional drying treatment to form an aluminum foil blank.

[0041] In this embodiment, the thickness of the aluminum foil substrate used is 20μm to 60μm; for example, the thickness of the aluminum foil substrate can be 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, or 60μm, etc., and this example does not impose any special limitation on this. Meanwhile, the aluminum foil substrate described herein has an upper surface and a lower surface that are disposed opposite to each other; it should also be noted that, since there may be subsequent differences between the various parts of the aluminum foil substrate, the thickness of the aluminum foil substrate can be used to characterize one of the maximum distance, minimum distance, or average distance between the upper surface and the lower surface. In this disclosure, the thickness of the aluminum foil substrate is used as an example of the average distance between the upper surface and the lower surface for illustration.

[0042] In this embodiment of the disclosure, the aluminum foil blank described above is obtained by: double-sided coating of the aluminum foil substrate with the mixed slurry to form a slurry film layer of the same thickness on the upper and lower surfaces of the aluminum foil substrate; directional drying treatment of the aluminum foil substrate having the slurry film layer to obtain the aluminum foil blank; wherein the thickness of the slurry film layer in the aluminum foil blank is 50μm~60μm. Further, when double-sided coating the aluminum foil substrate, coating methods such as blade coating and slot extrusion coating can be used to form a slurry film layer of the same thickness on the upper and lower surfaces of the aluminum foil substrate; simultaneously, the thickness of the slurry film layer can be 50μm, 52μm, 54μm, 56μm, 58μm, or 60μm, etc., and this example does not impose any special limitations on this; furthermore, by controlling the thickness of the aluminum foil substrate and the slurry film layer, a porous layer of suitable thickness can be formed on both sides of the aluminum foil blank. It should also be noted that the same thickness of the slurry film layer formed on the upper and lower surfaces of the aluminum foil substrate means that the thickness of the two is exactly the same or approximately the same. Due to process errors, the thickness difference between the two is within 1μm, and the thickness of the two can be considered to be the same.

[0043] In this embodiment, the directional drying process of aluminum foil with a slurry film layer can be achieved as follows: 20 to 100 sets of heating devices are arranged above and below the aluminum foil substrate with the slurry film layer; each set of heating devices includes two heating elements, the transverse axial directions of the two heating elements in the same set of heating devices forming angles of 30° to 60° and 120° to 150° with the length direction of the aluminum foil with the slurry film layer, respectively; during the directional drying process, the temperature of the heating elements is set to 200°C to 300°C; the interval between each heating element is cooled by room temperature air on the aluminum foil substrate with the slurry film layer; during this process, the aluminum foil with the slurry film layer is conveyed along its length at a speed of 1 m / min to 50 m / min; the heating elements include heating tubes and / or hot air nozzles. It should be noted that the directional drying process here involves one-time forming of the aluminum foil blank coated with slurry, the axial direction of the heating elements is not perpendicular to the foil's forward movement direction, and room temperature air is used to cool the foil between the heating elements. Compared to a single drying process followed by directional heat treatment, directional drying involves equipment upgrades and process simplification, thereby improving preparation efficiency.

[0044] In this embodiment, the heating devices arranged above and below the aluminum foil blank can be 20, 40, 60, 80, or 100 groups, etc., and this example does not impose any special limitations on this. Meanwhile, the transverse axial direction of one heating element in each group can be at an angle of 30°, 40°, 50°, or 60° to the length direction of the aluminum foil with the slurry film layer, etc.; furthermore, the transverse axial direction of the other heating element can be at an angle of 120°, 130°, 140°, or 150° to the length direction of the aluminum foil with the slurry film layer, etc.; simultaneously, the temperature of the heating elements can be set to 200℃, 220℃, 240℃, 260℃, 280℃, or 300℃, etc.; the room temperature can be assumed to be 20~25℃; the conveying speed of the aluminum foil blank along its length direction can be 1m / min, 10m / min, 20m / min, 30m / min, 40m / min, or 50m / min, etc., and this example does not impose any special limitations on this. It should also be noted that this method generates unevenly distributed internal stress in the slurry film by controlling the number, temperature, and angle of the heating devices and the speed of the aluminum foil blank conveying, thereby causing irregular multidirectional cracks in the slurry film during the subsequent sintering process, thus improving the bending performance of the anode foil.

[0045] In step S104, the aluminum foil blank is subjected to vibration treatment, and the vibrated aluminum foil blank is dried to form an initial anode foil; then the initial anode foil is sintered to form a target anode foil.

[0046] In this embodiment, the initial anode foil is determined as follows: the aluminum foil blank is immersed in an immersion solution, and then the aluminum foil blank in the immersion solution is vibrated using sound waves as a vibration source; then, the vibrated aluminum foil blank is dried at a drying temperature of 100℃~200℃ to obtain the initial anode foil. Specifically, the drying temperature described herein can be 100℃, 120℃, 140℃, 160℃, 180℃, or 200℃, etc., and this example does not impose any special limitations on this; the immersion solution described herein can include, but is not limited to, polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, ethylene glycol, propylene glycol, etc.; the vibration source (i.e., sound waves) described herein can be ultrasonic waves or megasonic waves. Furthermore, through vibration treatment, suitable internal stress is generated in the slurry film layer, thereby causing irregular multidirectional cracks to form in the slurry film layer during the subsequent sintering process, thereby improving the bending performance of the anode foil.

[0047] In this embodiment of the present disclosure, the target anode foil described above is obtained by the following method: In a nitrogen, argon, or vacuum atmosphere, the initial anode foil is heated from room temperature to 600°C to 650°C at a heating rate of 0.1°C / min to 20°C / min, and held at this temperature for 4 to 12 hours; after the holding period, it is cooled in the furnace, and then the cooled initial anode foil is subjected to a boiling treatment to form an intermediate anode foil; finally, the intermediate anode foil is subjected to a formation treatment to form an oxide layer on the intermediate anode foil to obtain the target anode foil. The heating rate described herein may include, but is not limited to, 0.1°C / min, 5°C / min, 10°C / min, 15°C / min, or 20°C / min; the holding temperature described herein may be 600°C, 610°C, 620°C, 630°C, 640°C, or 650°C; and the holding time described herein may be 4 hours, 6 hours, 8 hours, 10 hours, or 12 hours. It should also be noted that by adjusting and controlling parameters such as the heating rate, sintering atmosphere, holding temperature and holding time of the sintering process, the binder in the anode foil can be completely removed, while ensuring that the surface of the anode foil is flat and non-sticky, thus guaranteeing the flatness and integrity of the anode foil surface. Irregular multidirectional microcracks can also be generated on the surface and inside of the anode foil to improve the bending performance of the anode foil after subsequent formation treatment.

[0048] In this embodiment, the boiling treatment is achieved as follows: the cooled initial anode foil is boiled in deionized water at 100°C for 5 to 15 minutes; the formation voltage used in the formation process is 200V to 700V. It should be noted that the temperature of the deionized water can be strictly 100°C, but due to temperature error, it can also be within the range of 100°C ± 1°C, both of which can be considered as the required temperature for the boiling treatment. Simultaneously, the required boiling treatment time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, or 15 minutes, etc., and this example does not impose any special limitations on this. Furthermore, by adjusting and controlling the boiling treatment time and temperature, a hydrated alumina layer of suitable thickness can be formed on the surface of the anode foil, which is beneficial for the formation of an oxide layer in the subsequent formation process.

[0049] In this embodiment of the disclosure, the formation process described above includes forming the intermediate anode foil at a formation voltage of 200V to 700V. The formation voltage described here can be 200V, 300V, 400V, 500V, 600V, or 700V, etc., and the formation process can convert the hydrated alumina layer into an oxide layer (i.e., an alumina film layer). It should be noted that by adjusting and controlling the formation voltage, anode foils with various rated withstand voltage requirements can be produced.

[0050] Thus, the preparation method of the anode foil for aluminum electrolytic capacitors described in the exemplary embodiments of this disclosure has been fully realized. Based on the foregoing description, it can be understood that the preparation method of the anode foil for aluminum electrolytic capacitors described in the exemplary embodiments of this disclosure, on the one hand, involves controlling the composition of the mixed slurry and performing directional drying treatment on the slurry film layer. Specifically, the surface of the slurry film layer is confined and directionally heated along the transverse axis of the heating element. When the slurry passes through the heating zone before drying, the solvents and additives in the slurry are directionally heated and volatilized. After drying, the slurry film layer forms a micro-regionally non-uniform composition to improve the bending performance of the anode foil. On the other hand, because the coefficients of thermal expansion of the water-based resin, binder, and aluminum powder are different, when the dried slurry film layer passes through the heating zone, the slurry film layer expands due to heat, generating thermal stress. The slurry film layer undergoes multiple directional drying processes. Heating and cooling processes create unevenly distributed internal stresses in the slurry film, leading to irregular multidirectional cracks in the film during subsequent sintering, thus improving the bending performance of the anode foil. Furthermore, this preparation method employs vibration treatment to increase the unevenly distributed internal stresses in the slurry film, which are then superimposed with the sintering stresses generated during sintering. This results in irregular multidirectional microcracks forming in the slurry film after sintering, effectively avoiding the surface scratches and powdering problems that occur when applying stress or strain to the foil using rollers. This improves the surface quality of the anode foil, enabling the production of anode foils with intact surfaces and excellent bending performance.

[0051] This disclosure also provides an aluminum electrolytic capacitor; specifically, the aluminum electrolytic capacitor includes a target anode foil prepared by the method for preparing the aluminum electrolytic capacitor anode foil described in any one of the above-mentioned methods; at the same time, the aluminum electrolytic capacitor prepared based on the target anode foil has good mechanical properties and good overall device performance.

[0052] The following will further illustrate the preparation method of the anode foil for aluminum electrolytic capacitors provided in this disclosure through specific embodiments: Example 1: A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol) and the binder ethyl cellulose at a mass ratio of 100:10 and stir until homogeneous to form the first mixed solution.

[0053] Step 2: Mix deionized water and water-based resin (polyvinyl alcohol) at a mass ratio of 100:10 and stir until homogeneous to form a second mixed solution.

[0054] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (polyether defoamer, triethanolamine dispersant, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:100:2:1:6:1 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:150 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0055] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After directional drying, an aluminum foil blank is formed. 100 sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two heating tubes. The transverse axial directions of these two heating tubes are at angles of 40° and 140° to the length direction of the aluminum foil blank, respectively. The heating tube temperature is set to 200°C. The aluminum foil blank is cooled with room temperature air in the intervals between the heating tubes. The aluminum foil blank is conveyed at a speed of 50 m / min along its length. The thickness of the aluminum foil substrate is 20 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 52 μm.

[0056] Step 5: Immerse the aluminum foil blank formed in Step 4 in polyethylene glycol 400 and propylene glycol, use ultrasound as a vibration source to vibrate the aluminum foil blank, and then dry it at 140°C to form the initial anode foil.

[0057] Step 6: Sinter the initial anode foil formed in Step 5. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 640°C in a vacuum at a heating rate of 5°C / min, held at that temperature for 8 hours, and then cooled with the furnace after the holding period.

[0058] Step 7: The anode foil formed by sintering in Step 6 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 10 minutes; the formation treatment uses a 100 g / L boric acid solution and a formation voltage of 520 V.

[0059] Example 2: A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol and diethylene glycol butyl ether acetate) and the binder ethyl cellulose at a mass ratio of 50:50:1 and stir until homogeneous to form the first mixed solution.

[0060] Step 2: Mix deionized water and aqueous resin (polyvinylpyrrolidone and polyethylene glycol with a molecular weight of 2000~20000) at a mass ratio of 100:5:1 and stir until homogeneous to form a second mixed solution.

[0061] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organosilicone defoamer, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:80:2:5:0.5 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:40 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0062] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After directional drying, an aluminum foil blank is formed. Twenty sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two heating tubes. The transverse axial directions of these two heating tubes are at angles of 30° and 130° to the length direction of the aluminum foil blank, respectively. The heating tube temperature is set to 300°C. The aluminum foil blank is cooled with room temperature air in the intervals between the heating tubes. The aluminum foil blank is conveyed at a speed of 1 m / min along its length. The thickness of the aluminum foil substrate is 30 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 54 μm.

[0063] Step 5: Immerse the aluminum foil blank formed in Step 4 in polyethylene glycol 300 and propylene glycol, use megasonic waves as a vibration source to vibrate the aluminum foil blank, and then dry it at 180°C to form the initial anode foil.

[0064] Step 6: Sinter the initial anode foil formed in Step 5. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 610°C in argon gas at a heating rate of 15°C / min, held at that temperature for 10 hours, and then cooled with the furnace after the holding period.

[0065] Step 7: The anode foil formed in Step 6 is subjected to boiling and formation treatments. After rinsing with deionized water, it is dried at 100°C to form the target anode foil. The boiling treatment uses deionized water at 100°C for 5 minutes; the formation treatment uses a 100 g / L boric acid solution at a formation voltage of 200 V.

[0066] Example 3: A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (diethylene glycol butyl ether acetate) and the binder ethyl cellulose at a mass ratio of 100:5 and stir until homogeneous to form the first mixed solution.

[0067] Step 2: Mix deionized water and aqueous resin (polyvinyl alcohol, polyvinylpyrrolidone and hydroxyethyl cellulose) at a mass ratio of 100:1:1:1 and stir until homogeneous to form a second mixed solution.

[0068] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organic silicone defoamer and acrylate leveling agent) at a mass ratio of 100:10:0.5:0.5 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:100 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0069] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After directional drying, an aluminum foil blank is formed. Forty sets of heating devices are installed above and below the aluminum foil blank. Each heating device consists of two hot air nozzles. The transverse axial directions of these two hot air nozzles are at 50° and 150° angles to the length direction of the aluminum foil blank, respectively. The temperature of the hot air nozzles is set to 250°C. The aluminum foil blank is cooled with room temperature air in the intervals between the hot air nozzles. The aluminum foil blank is conveyed at a speed of 10 m / min along its length. The thickness of the aluminum foil substrate is 40 μm, and the thickness of the slurry coated on the upper and lower surfaces after drying is 50 μm.

[0070] Step 5: Immerse the aluminum foil blank formed in step 4 in ethylene glycol and propylene glycol, use megasonic waves as a vibration source to vibrate the aluminum foil blank, and then dry it at 200°C to form the initial anode foil.

[0071] Step 6: Sinter the initial anode foil formed in Step 5. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 620°C in nitrogen at a heating rate of 5°C / min, held at that temperature for 8 hours, and then cooled with the furnace after the holding period.

[0072] Step 7: The anode foil formed in Step 6 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 15 minutes; the formation treatment uses a 100g / L boric acid solution and a formation voltage of 700V.

[0073] Example 4: A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol) and the binder ethyl cellulose at a mass ratio of 100:3 and stir until homogeneous to form the first mixed solution.

[0074] Step 2: Mix deionized water and aqueous resin (hydroxyethyl cellulose and hydroxyethyl methyl cellulose) at a mass ratio of 100:0.5:0.5 and stir until homogeneous to form a second mixed solution.

[0075] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organic silicone defoamer, triethanolamine, and acrylate leveling agent) at a mass ratio of 100:60:3:1:1 and stir until homogeneous to form the third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:80 and stir until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a mass purity of 99.99%.

[0076] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After directional drying, an aluminum foil blank is formed. Eighty sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two heating tubes. The transverse axial directions of these two heating tubes are at angles of 60° and 120° to the length direction of the aluminum foil blank, respectively. The heating tube temperature is set to 280°C. The aluminum foil blank is cooled with room temperature air in the intervals between the heating tubes. The aluminum foil blank is conveyed at a speed of 30 m / min along its length. The thickness of the aluminum foil substrate is 50 μm, and the thickness of the slurry coated on the upper and lower surfaces after drying is 60 μm.

[0077] Step 5: Immerse the aluminum foil blank formed in Step 4 into polyethylene glycol 200 and ethylene glycol, use ultrasound as a vibration source to vibrate the aluminum foil blank, and then dry it at 120°C to form the initial anode foil.

[0078] Step 6: Sinter the initial anode foil formed in Step 5. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 650°C in argon gas at a heating rate of 0.1°C / min, held at that temperature for 4 hours, and then cooled with the furnace after the holding period.

[0079] Step 7: The anode foil formed in Step 6 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 10 minutes; the formation treatment uses a 100g / L boric acid solution and a formation voltage of 200V.

[0080] Example 5: A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol and diethylene glycol butyl ether acetate) with the binder ethyl cellulose at a mass ratio of 30:70:7 and stir until homogeneous to form the first mixed solution.

[0081] Step 2: Mix deionized water and aqueous resin (hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose) at a mass ratio of 100:0.5:5 and stir until homogeneous to form a second mixed solution.

[0082] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (diethanolamine, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:30:2:4:2 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:120 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0083] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After directional drying, an aluminum foil blank is formed. Sixty sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two hot air nozzles. The transverse axial directions of these two hot air nozzles are at angles of 45° and 135° to the length direction of the aluminum foil blank, respectively. The temperature of the hot air nozzles is set to 220°C. The aluminum foil blank is cooled with room temperature air in the intervals between the hot air nozzles. The aluminum foil blank is conveyed at a speed of 40 m / min along its length. The thickness of the aluminum foil substrate is 60 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 58 μm.

[0084] Step 5: Immerse the aluminum foil blank formed in step 4 in ethylene glycol, use megasonic waves as a vibration source to vibrate the aluminum foil blank, and then dry it at 100°C to form the initial anode foil.

[0085] Step 6: Sinter the initial anode foil formed in Step 5. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 600°C in a vacuum at a heating rate of 20°C / min, held at that temperature for 12 hours, and then cooled with the furnace after the holding period.

[0086] Step 7: The anode foil formed in Step 6 is subjected to boiling and formation treatments. After rinsing with deionized water, it is dried at 100°C to form the target anode foil. The boiling treatment uses deionized water at 100°C for 5 minutes; the formation treatment uses a 100 g / L boric acid solution at a formation voltage of 520 V.

[0087] Example 6: A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (diethylene glycol butyl ether acetate) and the binder ethyl cellulose at a mass ratio of 100:2 and stir until homogeneous to form the first mixed solution.

[0088] Step 2: Mix deionized water and aqueous resin (polyvinyl alcohol, hydroxyethyl cellulose and hydroxypropyl methyl cellulose) at a mass ratio of 100:0.5:2:6 and stir until homogeneous to form a second mixed solution.

[0089] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organosilicone defoamer, diethanolamine, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:70:1:2:2:1 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:60 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0090] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After directional drying, an aluminum foil blank is formed. Fifty sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two heating tubes. The transverse axial directions of these two heating tubes are at angles of 30° and 140° to the length direction of the aluminum foil blank, respectively. The heating tube temperature is set to 260°C. The aluminum foil blank is cooled with room temperature air in the intervals between the heating tubes. The aluminum foil blank is conveyed at a speed of 20 m / min along its length. The thickness of the aluminum foil substrate is 20 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 56 μm.

[0091] Step 5: Immerse the aluminum foil blank formed in Step 4 in polyethylene glycol 300, ethylene glycol and propylene glycol, use ultrasound as a vibration source to vibrate the aluminum foil blank, and then dry it at 160°C to form the initial anode foil.

[0092] Step 6: Sinter the initial anode foil formed in Step 5. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 630°C in nitrogen at a heating rate of 10°C / min, held at that temperature for 10 hours, and then cooled with the furnace after the holding period.

[0093] Step 7: The anode foil formed in Step 6 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 15 minutes; the formation treatment uses a 100g / L boric acid solution and a formation voltage of 700V.

[0094] Comparative Example 1 (also known as Comparative Example 1): A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol) and the binder ethyl cellulose at a mass ratio of 100:10 and stir until homogeneous to form the first mixed solution.

[0095] Step 2: Mix deionized water and water-based resin (polyvinyl alcohol) at a mass ratio of 100:10 and stir until homogeneous to form a second mixed solution.

[0096] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (polyether defoamer, triethanolamine dispersant, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:100:2:1:6:1 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:150 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0097] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After drying, an aluminum foil blank is formed. 100 sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two heating tubes, with the transverse axial direction of these two heating tubes at a 90° angle to the length direction of the aluminum foil blank. The heating tube temperature is set to 200℃. The aluminum foil blank is conveyed at a speed of 50 m / min along its length. The thickness of the aluminum foil substrate is 20 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 52 μm.

[0098] Step 5: Cracks are created on the surface of the aluminum foil blank formed in Step 4 by passing it through a 12mm diameter roller. The process is as follows: First, the aluminum foil blank is passed through the roller at a 30° angle to the roller's axis, and this is repeated 10 times. Then, the aluminum foil blank is passed through the roller at a 150° angle to the roller's axis, and this is repeated 10 times.

[0099] Step 6: Sinter the aluminum foil blank formed in Step 5. Sintering is carried out in a bell-type furnace. The sintering process is as follows: heat to 640°C in a vacuum at a heating rate of 5°C / min, hold for 8 hours, and then cool with the furnace after the holding period.

[0100] Step 7: The anode foil formed in Step 6 is subjected to boiling and formation treatments. After rinsing with deionized water, it is dried at 100°C to form the target anode foil. The boiling treatment uses deionized water at 100°C for 10 minutes; the formation treatment uses a 100 g / L boric acid solution at a formation voltage of 520 V.

[0101] Comparative Example 2 (also known as Comparative Example 2): A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol) and the binder ethyl cellulose at a mass ratio of 100:10 and stir until homogeneous to form the first mixed solution.

[0102] Step 2: Mix deionized water and water-based resin (polyvinyl alcohol) at a mass ratio of 100:10 and stir until homogeneous to form a second mixed solution.

[0103] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (polyether defoamer, triethanolamine dispersant, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:100:2:1:6:1 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:150 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0104] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After drying, an aluminum foil blank is formed. 100 sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two heating tubes, with the transverse axial direction of these two heating tubes at a 90° angle to the length direction of the aluminum foil blank. The heating tube temperature is set to 200℃. The aluminum foil blank is conveyed at a speed of 50 m / min along its length. The thickness of the aluminum foil substrate is 20 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 52 μm.

[0105] Step 5: Sinter the aluminum foil blank formed in Step 4. Sintering is carried out in a bell-type furnace. The sintering process is as follows: heat to 640°C in a vacuum at a heating rate of 5°C / min, hold for 8 hours, and then cool with the furnace after the holding period.

[0106] Step 6: The anode foil formed in Step 5 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 10 minutes; the formation treatment uses a 100 g / L boric acid solution and a formation voltage of 520 V.

[0107] Comparative Example 3 (also known as Comparative Example 3): A method for preparing the anode foil of an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol and diethylene glycol butyl ether acetate) and the binder ethyl cellulose at a mass ratio of 50:50:1 and stir until homogeneous to form the first mixed solution.

[0108] Step 2: Mix deionized water and aqueous resin (polyvinylpyrrolidone and polyethylene glycol with a molecular weight of 2000~20000) at a mass ratio of 100:5:1 and stir until homogeneous to form a second mixed solution.

[0109] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organosilicone defoamer, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:80:2:5:0.5 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:40 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0110] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After drying, an aluminum foil blank is formed. Twenty sets of heating devices are installed above and below the aluminum foil blank. Each set of heating devices consists of two heating tubes, with the transverse axial direction of these two heating tubes at a 90° angle to the length direction of the aluminum foil blank. The heating tube temperature is set to 300℃. The aluminum foil blank is conveyed at a speed of 1 m / min along its length. The thickness of the aluminum foil substrate is 30 μm, and the thickness of the slurry coated on both the upper and lower surfaces after drying is 54 μm.

[0111] Step 5: Sinter the aluminum foil blank formed in Step 4. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 610°C in argon gas at a heating rate of 15°C / min, held at that temperature for 10 hours, and then cooled with the furnace after the holding period.

[0112] Step 6: The anode foil formed in Step 5 is subjected to boiling and formation treatments. After rinsing with deionized water, it is dried at 100°C to form the target anode foil. The boiling treatment uses deionized water at 100°C for 5 minutes; the formation treatment uses a 100 g / L boric acid solution at a formation voltage of 200 V.

[0113] Comparative Example 4: A method for preparing an anode foil for an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (diethylene glycol butyl ether acetate) and the binder ethyl cellulose at a mass ratio of 100:5 and stir until homogeneous to form the first mixed solution.

[0114] Step 2: Mix deionized water and aqueous resin (polyvinyl alcohol, polyvinylpyrrolidone and hydroxyethyl cellulose) at a mass ratio of 100:1:1:1 and stir until homogeneous to form a second mixed solution.

[0115] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organic silicone defoamer and acrylate leveling agent) at a mass ratio of 100:10:0.5:0.5 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:100 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0116] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After drying, an aluminum foil blank is formed. Forty sets of heating devices are installed above and below the aluminum foil blank. Each heating device consists of two hot air nozzles. The transverse axial direction of these two hot air nozzles is at a 90° angle to the length direction of the aluminum foil blank. The hot air nozzle temperature is set to 250℃. The conveying speed of the aluminum foil blank along its length is 10 m / min. The thickness of the aluminum foil substrate is 40 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 50 μm.

[0117] Step 5: Sinter the aluminum foil blank formed in Step 4. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 620°C in nitrogen at a heating rate of 5°C / min, held at that temperature for 8 hours, and then cooled with the furnace after the holding period.

[0118] Step 6: The anode foil formed in Step 5 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 15 minutes; the formation treatment uses a 100 g / L boric acid solution and a formation voltage of 700 V.

[0119] Comparative Example 5: A method for preparing an anode foil for an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol) and the binder ethyl cellulose at a mass ratio of 100:3 and stir until homogeneous to form the first mixed solution.

[0120] Step 2: Mix deionized water and aqueous resin (hydroxyethyl cellulose and hydroxyethyl methyl cellulose) at a mass ratio of 100:0.5:0.5 and stir until homogeneous to form a second mixed solution.

[0121] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organic silicone defoamer, triethanolamine, and acrylate leveling agent) at a mass ratio of 100:60:3:1:1 and stir until homogeneous to form the third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:80 and stir until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a mass purity of 99.99%.

[0122] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After drying, an aluminum foil blank is formed. Eighty sets of heating devices are installed above and below the aluminum foil blank. Each heating device consists of two heating tubes, with their transverse axial direction at a 90° angle to the length direction of the aluminum foil blank. The heating tube temperature is set to 280℃. The aluminum foil blank is conveyed at a speed of 30 m / min along its length. The thickness of the aluminum foil substrate is 50 μm, and the thickness of the slurry applied to the upper and lower surfaces after drying is 60 μm.

[0123] Step 5: Sinter the aluminum foil blank formed in Step 4. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 650°C in argon gas at a heating rate of 0.1°C / min, held at that temperature for 4 hours, and then cooled with the furnace after the holding period.

[0124] Step 6: The anode foil formed in Step 5 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 10 minutes; the formation treatment uses a 100g / L boric acid solution and a formation voltage of 200V.

[0125] Comparative Example 6: A method for preparing an anode foil for an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (terpineol and diethylene glycol butyl ether acetate) with the binder ethyl cellulose at a mass ratio of 30:70:7 and stir until homogeneous to form the first mixed solution.

[0126] Step 2: Mix deionized water and aqueous resin (hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose) at a mass ratio of 100:0.5:5 and stir until homogeneous to form a second mixed solution.

[0127] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (diethanolamine, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:30:2:4:2 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:120 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0128] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After drying, an aluminum foil blank is formed. Sixty sets of heating devices are installed above and below the aluminum foil blank. Each heating device consists of two hot air nozzles, with the lateral axis of these two nozzles at a 90° angle to the length direction of the aluminum foil blank. The hot air nozzle temperature is set to 220℃. The conveying speed of the aluminum foil blank along its length is 40 m / min. The thickness of the aluminum foil substrate is 60 μm, and the thickness of the slurry coated on both the upper and lower surfaces after drying is 58 μm.

[0129] Step 5: Sinter the aluminum foil blank formed in Step 4. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 600°C in a vacuum at a heating rate of 20°C / min, held at that temperature for 12 hours, and then cooled with the furnace after the holding period.

[0130] Step 6: The anode foil formed in Step 5 is subjected to boiling and formation treatments. After rinsing with deionized water, it is dried at 100°C to form the target anode foil. The boiling treatment uses deionized water at 100°C for 5 minutes; the formation treatment uses a 100 g / L boric acid solution at a formation voltage of 520 V.

[0131] Comparative Example 7 (also known as Comparative Example 7): A method for preparing an anode foil for an aluminum electrolytic capacitor, comprising the following steps: Step 1: Mix the organic solvent (diethylene glycol butyl ether acetate) and the binder ethyl cellulose at a mass ratio of 100:2 and stir until homogeneous to form the first mixed solution.

[0132] Step 2: Mix deionized water and aqueous resin (polyvinyl alcohol, hydroxyethyl cellulose and hydroxypropyl methyl cellulose) at a mass ratio of 100:0.5:2:6 and stir until homogeneous to form a second mixed solution.

[0133] Step 3: Mix the first mixed solution, the second mixed solution, and the additives (organosilicone defoamer, diethanolamine, silane coupling agent, and acrylate leveling agent) at a mass ratio of 100:70:1:2:2:1 until homogeneous to form a third mixed solution. Mix the aluminum powder with the third mixed solution at a mass ratio of 100:60 until homogeneous to form a mixed slurry; wherein the aluminum powder has a particle size of 0.5μm~5μm and a purity of 99.99%.

[0134] Step 4: The mixed slurry formed in Step 3 is applied to the upper and lower surfaces of the aluminum foil substrate using a slit extrusion coating method. After drying, an aluminum foil blank is formed. Fifty sets of heating devices are installed above and below the aluminum foil blank. Each heating device consists of two heating tubes, with their transverse axial direction at a 90° angle to the length direction of the aluminum foil blank. The heating tube temperature is set to 260℃. The aluminum foil blank is conveyed at a speed of 20 m / min along its length. The thickness of the aluminum foil substrate is 20 μm. The thickness of the slurry coated on both the upper and lower surfaces after drying is 56 μm.

[0135] Step 5: Sinter the aluminum foil blank formed in Step 4. Sintering is carried out in a bell-type furnace. The sintering process is as follows: the bell-type furnace is heated to 630°C in nitrogen at a heating rate of 10°C / min, held at that temperature for 10 hours, and then cooled with the furnace after the holding period.

[0136] Step 6: The anode foil formed in Step 5 is subjected to boiling water treatment and formation treatment. After washing with deionized water, it is dried at 100°C to form the target anode foil. The boiling water treatment uses deionized water at 100°C for 15 minutes; the formation treatment uses a 100 g / L boric acid solution and a formation voltage of 700 V.

[0137] Under the aforementioned conditions, when the target anode foil was tested for bending performance using a clamp with a radius of curvature of 3.5 mm (referring to the electronic industry standard: SJ / T 11140-2022 Electrode Foil for Aluminum Electrolytic Capacitors), the anode foil formed in Comparative Example 1 (i.e., Comparative Example 1) exhibited 165 longitudinal bends and 138 transverse bends; the anode foil formed in Comparative Example 2 (i.e., Comparative Example 2) exhibited 8 longitudinal bends and 5 transverse bends; and the anode foil formed in Example 1 exhibited 178 longitudinal bends and 156 transverse bends. Compared to Comparative Example 1 and Comparative Example 2 (i.e., Comparative Example 2), the anode foil formed in Example 1 exhibited the highest number of bends. Furthermore, Figure 2 The image shows a light microscope image of the anode foil prepared using the method provided in Comparative Example 1 (i.e., Comparative Example 1). Figure 3 Figure 4(a) shows an optical microscope image of an anode foil formed using the preparation method provided in Comparative Example 2 (i.e., Comparative Example 2). Figure 1 Figure 4(b) is an optical mirror of the anode foil formed using the preparation method provided in Example 1. Figure 2 .from Figure 2 It can be seen that the anode foil formed in Comparative Example 1 (i.e., Comparative Example 1) has irregular multidirectional microcracks, but the surface of the anode foil has defects such as scratches and powder shedding; from Figure 3As can be seen, the surface of the anode foil formed in Comparative Example 2 (i.e., Comparative Example 2) is free of cracks; as can be seen from Figure 4(a), the surface of the anode foil formed in Example 1 has irregular multi-directional microcracks; as can be seen from Figure 4(b), the surface quality of the anode foil formed in Example 1 is good, and there are no defects such as scratches and powder shedding; the preparation method of Example 1 can form an anode foil with a complete surface and good bending performance.

[0138] Meanwhile, the bending performance test results (clamp curvature radius of 3.5 mm) of the anode foils prepared in Comparative Examples 1-7 and Examples 1-6 are shown in Table 1 below: Table 1

[0139] As shown in Table 1 above, the anode foil prepared in Comparative Example 1, processed by inclined rollers, had 165 longitudinal bends and 138 transverse bends. The anode foil prepared in Example 1, processed by vibration, had 178 longitudinal bends and 156 transverse bends. The anode foil prepared in Example 1 showed an increase in the number of bends compared to the anode foil prepared in Comparative Example 1. Furthermore, the anode foils prepared in Comparative Examples 2-7 without vibration processing exhibited poor longitudinal and transverse bending performance, with each foil having fewer than 10 bends. The anode foils prepared in Examples 1-6, processed by vibration, achieved more than 170 longitudinal bends and more than 140 transverse bends. Comparing Comparative Examples 2-7 and Examples 1-6 as described above, under the same test conditions, the anode foils prepared in Examples 1-6 had more than 15 times more bends than those prepared in Comparative Examples 2-7, significantly improving the longitudinal and transverse bending performance of the anode foil and meeting machining requirements. Therefore, the method for preparing the anode foil provided in this disclosure can improve the bending performance of the anode foil, thereby improving the overall performance of the device.

[0140] Furthermore, although the steps of the method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or a step may be broken down into multiple steps.

[0141] Furthermore, the above figures are merely illustrative representations of the processes included in the method according to exemplary embodiments of this disclosure, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0142] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention described herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not invented by this disclosure. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

Claims

1. A method for preparing the anode foil of an aluminum electrolytic capacitor, characterized in that, include: Step S101: Prepare a first mixed solution and a second mixed solution. The first mixed solution is prepared by mixing an organic solvent and a binder, and the second mixed solution is prepared by mixing deionized water and a water-based resin. Step S102: Prepare a mixed slurry, the mixed slurry comprising aluminum powder and a third mixed solution, the third mixed solution being a mixture of a first mixed solution, a second mixed solution and additives; Step S103: Provide an aluminum foil substrate and coat the surface of the aluminum foil substrate with the mixed slurry; then, perform directional drying treatment on the aluminum foil having the slurry film layer to form an aluminum foil blank; In step S104, the aluminum foil blank is subjected to vibration treatment, and the aluminum foil blank after vibration treatment is dried to form an initial anode foil; then, the initial anode foil is sintered to form a target anode foil.

2. The preparation method according to claim 1, characterized in that, In the first mixed solution, the mass ratio between the organic solvent and the binder is 100:(1~10); The organic solvent includes terpineol and / or diethylene glycol butyl ether acetate; The binder is ethyl cellulose.

3. The preparation method according to claim 1, characterized in that, In the second mixed solution, the mass ratio between the deionized water and the aqueous resin is 100:(1~10); The aqueous resin includes one or more of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose; The molecular weight of the polyethylene glycol is 2000~20000.

4. The preparation method according to claim 1, characterized in that, In the mixed slurry, the mass ratio of the aluminum powder to the third mixed solution is 100:(40~150); In the third mixed solution, the mass ratio of the first mixed solution, the second mixed solution, and the additive is 100:(10~100):(1~10); The additives include a first additive and a second additive, wherein the first additive is a leveling agent and the second additive includes one or more of an antifoaming agent, a dispersant, and a coupling agent. The defoamer is an organosilicon defoamer or a polyether defoamer, the dispersant is diethanolamine or triethanolamine, the coupling agent is a silane coupling agent, and the leveling agent is an acrylate leveling agent.

5. The preparation method according to claim 1, characterized in that, The aluminum foil substrate has a thickness of 20μm to 60μm and has an upper surface and a lower surface that are disposed opposite to each other. The aluminum foil blank is obtained by coating the aluminum foil substrate on both sides using the mixed slurry to form a slurry film layer of the same thickness on the upper and lower surfaces of the aluminum foil substrate. An aluminum foil substrate having the slurry film layer is subjected to directional drying treatment to obtain the aluminum foil blank; wherein the thickness of the slurry film layer in the aluminum foil blank is 50μm~60μm.

6. The preparation method according to claim 5, characterized in that, The directional drying process of the aluminum foil substrate having the slurry film layer is achieved by setting 20 to 100 sets of heating devices above and below the aluminum foil substrate having the slurry film layer. Each heating device includes two heating elements. The transverse axial directions of the two heating elements in the same heating device form angles of 30°~60° and 120°~150° with the length direction of the aluminum foil substrate with the slurry film layer, respectively. During the directional drying process, the temperature of the heating elements is set to 200°C~300°C. The aluminum foil substrate with the slurry film layer is cooled by room temperature air in the interval between each heating element. The speed at which the aluminum foil substrate with the slurry film layer is conveyed along the length direction is 1m / min~50m / min. The heating element includes a heating tube and / or a hot air nozzle.

7. The preparation method according to claim 1, characterized in that, The initial anode foil is determined by immersing the aluminum foil blank in an immersion solution, then vibrating the aluminum foil blank in the immersion solution using sound waves as a vibration source; then drying the vibrated aluminum foil blank at a drying temperature of 100℃~200℃ to obtain the initial anode foil.

8. The preparation method according to claim 7, characterized in that, The soaking solution includes one or more of polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, ethylene glycol, and propylene glycol; The sound waves include ultrasonic waves or megasonic waves.

9. The preparation method according to claim 1, characterized in that, The target anode foil is obtained as follows: In a nitrogen, argon, or vacuum atmosphere, the initial anode foil is heated from room temperature to 600℃~650℃ at a heating rate of 0.1℃ / min~20℃ / min and held at this temperature for 4h~12h; after the holding period, it is cooled in the furnace, and then the cooled initial anode foil is subjected to a boiling treatment to form an intermediate anode foil; finally, the intermediate anode foil undergoes a formation treatment to form an oxide layer on the intermediate anode foil to obtain the target anode foil. The boiling treatment is achieved as follows: the cooled initial anode foil is boiled in deionized water at 100°C for 5 to 15 minutes; the formation voltage used in the formation treatment is 200V to 700V.

10. An aluminum electrolytic capacitor, characterized in that, The aluminum electrolytic capacitor includes the target anode foil prepared by the method for preparing the anode foil of the aluminum electrolytic capacitor according to any one of claims 1-9.

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