A preparation method of an anode foil for an aluminum electrolytic capacitor

Abstract

The present disclosure provides a method for preparing an anode foil of an aluminum electrolytic capacitor, which relates to the technical field of capacitors. The method includes: preparing aluminum paste; providing an aluminum foil substrate, coating the aluminum paste on the surface of the aluminum foil substrate, and performing a drying treatment to form an aluminum foil blank; performing a water washing treatment on the aluminum foil blank and drying it to obtain a porous aluminum foil blank; performing a heat treatment on the porous aluminum foil blank; coating a film solution on the surface of the heat-treated porous aluminum foil blank and performing a drying treatment to form a protective film layer on the surface of the porous aluminum foil blank; using a rolling mill to perform a rolling treatment on the porous aluminum foil blank with the protective film layer in an inclined rolling manner to obtain an initial anode foil; performing a sintering treatment on the initial anode foil to remove the protective film layer to form a sintered foil. This preparation method can improve the anti-bending performance of the anode foil.

Description

Technical Field

[0001] The present disclosure relates to the technical field of capacitors, and more particularly, to a method for preparing an anode foil of an aluminum electrolytic capacitor. Background Art

[0002] Aluminum electrolytic capacitors have the advantages of small volume, low cost, large capacitance, etc., and are widely used in the field of the electronics industry. With the development of technology, higher requirements are put forward for the overall performance and size of devices applied in automotive electronics, household appliances, industrial control, etc. The performance and quality of aluminum electrolytic capacitors also need to be matched with the overall performance of the devices, which promotes the further development of aluminum electrolytic capacitors towards high capacitance, miniaturization, and greening, etc. The requirement for the bending resistance of the anode foil of aluminum electrolytic capacitors is also getting higher and higher.

[0003] Currently, the anode foil of an aluminum electrolytic capacitor can be prepared by sintering a porous aluminum powder layer on the surface of an aluminum foil substrate, but the formed anode foil has poor bending resistance and cannot meet the mechanical processing requirements. To improve the bending resistance of the anode foil, cracks can be processed on the surface of the foil by an inclined roller (with a diameter of 6 mm to 20 mm). The foil passes around a conveying roller and a roller. The conveying roller is used to convey the foil forward, and the foil bypasses the roller in an inclined manner. Since the bending contact surface forms an angle with the width direction of the foil, corresponding cracks are generated when passing through the roller. Multiple sets of rollers can be provided to process multiple cracks simultaneously; alternatively, a number of balls (with a diameter of 2 mm to 4 mm) that can rotate around their own centers of the sphere are provided on the circumferential surface of a roller (with a diameter of 8 mm to 12 mm). The balls are in contact with the electrode foil, and by making the foil surface of the electrode foil roll relative to the balls that can rotate in multiple directions around their own centers of the sphere and under the interaction of the winding tension, cracks in multiple directions are formed on the foil surface of the electrode foil. However, the surface of the anode foil prepared by the above two methods is prone to surface scratches and powder falling, and the flatness and integrity of the anode foil surface cannot be guaranteed, resulting in easy adhesion of the foil during the coiling and sintering of the aluminum foil; in addition, the existing technology uses small-diameter rollers (20 mm and below), and the stiffness of the small rollers is poor, which is prone to bending during continuous processing of the foil, easily causing foil wrinkles, and thus resulting in the inability to produce an anode foil with a flat surface and good bending resistance.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] In view of this, a method for preparing an anode foil of an aluminum electrolytic capacitor is provided. This preparation method can improve the bending resistance of the anode foil, reduce the defects on the surface of the anode foil, and ensure the integrity and flatness of the anode foil surface.

[0006] Other features and advantages of the present disclosure will become apparent from the following detailed description, or will be partially learned through the practice of the present disclosure.

[0007] According to one aspect of the present disclosure, a method for preparing an anode foil of an aluminum electrolytic capacitor is provided. The preparation method includes:

[0008] Step S1: Prepare an aluminum paste. The aluminum paste includes a mixed solution and a solid aluminum-containing powder. The mixed solution is prepared by mixing a solvent, a binder, and an additive. The solid aluminum-containing powder includes aluminum powder and a water-soluble pore-forming agent;

[0009] Step S2: Provide an aluminum foil substrate, coat the aluminum paste on the surface of the aluminum foil substrate, and perform a drying treatment to form an aluminum foil blank;

[0010] Step S3: Wash the dried aluminum foil blank with water and then dry it to obtain a porous aluminum foil blank;

[0011] Step S4: Perform a heat treatment on the porous aluminum foil blank;

[0012] Step S5: Coat a film solution on the surface of the heat-treated porous aluminum foil blank and perform a drying treatment to form a protective film layer on the surface of the porous aluminum foil blank;

[0013] Step S6: Use a rolling mill to roll the porous aluminum foil blank with the protective film layer in a skew rolling manner to obtain an initial anode foil;

[0014] Step S7: Perform a sintering treatment on the initial anode foil to remove the protective film layer to form a sintered foil.

[0015] In an exemplary embodiment of the present disclosure, the rolling mill is one of a two-high rolling mill, a three-high rolling mill, or a four-high rolling mill. The reduction of the rolling mill rolls is 5 μm to 15 μm, and the diameter of the rolling mill rolls is 65 mm to 600 mm. In step S6, use a rolling mill to roll the porous aluminum foil blank with the protective film layer in a skew rolling manner to obtain an initial anode foil. The method includes:

[0016] Perform a first rolling treatment on the porous aluminum foil blank with the protective film layer. The first rolling treatment is to repeat rolling the porous aluminum foil blank 2 to 20 times when the axis direction of the rolling mill rolls forms an angle of 20° to 70° with the length direction of the porous aluminum foil blank;

[0017] Then, perform a second rolling process on the porous aluminum foil blank with the protective film layer. The second rolling process is to repeat rolling the porous aluminum foil blank 2 to 20 times when the axial direction of the rolling mill rolls is at an angle of 110° to 160° with the length direction of the porous aluminum foil blank.

[0018] In an exemplary embodiment of the present disclosure, the thin film solution is an aqueous solution prepared from one or more of hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone. In step S5, coating the thin film solution on the surface of the heat-treated porous aluminum foil blank, the method includes:

[0019] Use one form of knife coating or screen printing to perform double-sided coating of the thin film solution on the porous aluminum foil blank; the thickness of the protective film layer is the same on each side of the porous aluminum foil blank, and the thickness of the protective film layer on each side of the porous aluminum foil blank is 5 μm to 30 μm.

[0020] In an exemplary embodiment of the present disclosure, the mass fraction of the water-soluble pore-forming agent in the solid aluminum-containing powder is 0.5% to 4%; the mass ratio of the mixed solution to the solid aluminum-containing powder is 100:(80 - 250);

[0021] The water-soluble pore-forming agent is one or more of water-soluble neutral salts, water-soluble starches, and water-soluble resins;

[0022] The water-soluble neutral salts are one or more of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate;

[0023] The water-soluble starches are one or more of modified corn starch, modified potato starch, modified sweet potato starch, modified cassava starch, modified wheat starch, and modified mung bean starch;

[0024] The water-soluble resins are one or more of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose.

[0025] In an exemplary embodiment of the present disclosure, in step S3, perform a water washing process on the dried aluminum foil blank and then dry it to obtain a porous aluminum foil blank, including:

[0026] Wash the aluminum foil blank with deionized water at 10°C to 80°C, and the washing method is one of immersion or ultrasonic cleaning;

[0027] Dry the washed aluminum foil blank at a drying temperature of 40°C to 120°C.

[0028] In an exemplary embodiment of the present disclosure, in step S4, heat treatment of the porous aluminum foil blank includes:

[0029] In an air atmosphere, heat the porous aluminum foil blank from room temperature to 300°C - 500°C at a heating rate of 0.1°C / min - 20°C / min, and hold for 1 h - 8 h;

[0030] In a nitrogen, argon or vacuum atmosphere, continue to heat the porous aluminum foil blank to 570°C - 600°C at a heating rate of 0.1°C / min - 20°C / min, and hold for 4 h - 12 h;

[0031] After the holding is completed, cool it in the furnace.

[0032] In an exemplary embodiment of the present disclosure, the mass ratio of the solvent, binder, and additive in the mixed solution is 100:(3 - 10):(0.5 - 10);

[0033] The solvent is a mixture of a first solvent and a second solvent. The first solvent is one or two of terpineol and diethylene glycol butyl ether acetate, and the second solvent is one or more of ethylene glycol, propylene glycol, and glycerol;

[0034] The binder is one or two of ethyl cellulose and polyvinyl butyral;

[0035] The additive includes one or more of an antifoaming agent, a leveling agent, a dispersant, and a coupling agent. The antifoaming agent is an organosilicon antifoaming agent or a polyether antifoaming agent, the leveling agent is an acrylate leveling agent, the dispersant is triethanolamine, and the coupling agent is a silane coupling agent.

[0036] In an exemplary embodiment of the present disclosure, the thickness of the aluminum foil substrate is 20 μm - 60 μm. The aluminum foil substrate has an upper surface and a lower surface arranged oppositely. In step S2, forming the aluminum foil blank, the method includes:

[0037] Use the aluminum paste to coat both sides of the aluminum foil substrate to form aluminum paste film layers of the same thickness on the upper surface and the lower surface of the aluminum foil substrate;

[0038] Under the condition that the drying temperature is 90°C - 200°C, dry the aluminum foil substrate with the aluminum paste film layer. The thickness of the dried aluminum paste film layer is 50 μm - 60 μm.

[0039] In an exemplary embodiment of the present disclosure, in step S7, the sintering treatment includes:

[0040] In a nitrogen, argon or vacuum atmosphere, the initial anode foil is heated from room temperature to 610°C to 650°C at a heating rate of 0.1°C / min to 20°C / min and held for 4 h to 12 h;

[0041] After the heat preservation is completed, it is cooled in the furnace.

[0042] In an exemplary embodiment of the present disclosure, after step S7, the method further includes:

[0043] The sintered foil is subjected to a water boiling treatment to form an intermediate anode foil. The water boiling treatment includes boiling the sintered foil in deionized water at 100°C for 5 min to 15 min;

[0044] The intermediate anode foil is subjected to a forming treatment to form an oxide layer on the intermediate anode foil to obtain a target anode foil. The forming voltage of the forming treatment is 200 V to 700 V;

[0045] The target anode foil is subjected to cleaning and drying treatments.

[0046] The method for preparing the anode foil of the aluminum electrolytic capacitor provided by the present disclosure adds a water-soluble pore-forming agent to the aluminum paste. The aluminum paste is coated on the surface of the aluminum foil substrate and dried to obtain an aluminum foil blank, and then the porous aluminum foil blank is obtained through water washing and drying. Then, through heat treatment and coating a protective film layer on the surface of the porous aluminum foil blank, a sintered foil with irregular multi-directional cracks on the surface and inside is obtained through rolling treatment and sintering. By adding a water-soluble pore-forming agent to the aluminum paste in this preparation method, the porosity of the aluminum foil blank can be increased, which is beneficial to the formation of internal stress in the aluminum foil blank during subsequent rolling treatment to form cracks during the sintering process. In addition, the surface and inside of the sintered foil obtained by this method have irregular multi-directional cracks, which can improve the anti-bending performance of the subsequent anode foil. In addition, in this preparation method, after coating a protective film layer on the surface of the porous aluminum foil blank first and then performing diagonal rolling through a rolling mill, the problem of surface scratching and powder falling of the anode foil can be solved. The protective film layer can form a gap between adjacent porous aluminum foil blanks to avoid adhesion between the porous aluminum foil blanks during the subsequent sintering process. In addition, the rolling mill used in this preparation method is a large-diameter roll (with a diameter of 65 mm - 300 mm), and the stiffness of the roll is better, which can effectively improve the problem of foil wrinkling caused by roll bending and improve the production quality of the anode foil. Through this preparation method, an anode foil with a flat surface and good anti-bending performance can be produced.

[0047] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. Description of the Drawings

[0048] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0049] Figure 1 It is a flowchart of a method for preparing an anode foil of an aluminum electrolytic capacitor in an exemplary embodiment of the present disclosure.

[0050] Figure 2 It is a light microscope image of the anode foil prepared in Comparative Example 1.

[0051] Figure 3 It is a light microscope image of the anode foil prepared in Comparative Example 2.

[0052] Figure 4 It is a light microscope image of the anode foil prepared in Example 1 of the present disclosure. Detailed Embodiments

[0053] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0054] The terms "a", "an", "the", "said" and "at least one" are used to denote the presence of one or more elements / components / etc.; the terms "comprising" and "having" are used to denote an open inclusive meaning and mean that there may be additional elements / components / etc. in addition to the listed elements / components / etc.; the terms "first", "second", "third", etc. are used only as labels and are not a limitation on the quantity of their objects.

[0055] Based on this, the embodiments of the present disclosure provide a method for preparing an anode foil of an aluminum electrolytic capacitor, as Figure 1 shown, the preparation method includes: Step S1 to Step S7.

[0056] Among them, in Step S1: Prepare an aluminum paste, the aluminum paste includes a mixed solution and a solid aluminum-containing powder, the mixed solution is prepared by mixing a solvent, a binder and an additive, and the solid aluminum-containing powder includes aluminum powder and a water-soluble pore-forming agent;

[0057] Step S2: Provide an aluminum foil substrate, coat the aluminum paste on the surface of the aluminum foil substrate to form an aluminum foil blank, and perform a drying treatment on the aluminum foil blank;

[0058] Step S3: Perform a water washing treatment on the dried aluminum foil blank and then dry it to obtain a porous aluminum foil blank;

[0059] Step S4: Perform a heat treatment on the porous aluminum foil blank;

[0060] Step S5: Coat a thin film solution on the surface of the heat-treated porous aluminum foil blank and perform a drying treatment to form a protective film layer on the surface of the porous aluminum foil blank;

[0061] Step S6: Use a rolling mill to perform a rolling treatment on the porous aluminum foil blank with a protective film layer in a skew rolling manner to obtain an initial anode foil;

[0062] Step S7: Perform a sintering treatment on the initial anode foil to remove the protective film layer to form a sintered foil.

[0063] The preparation method of the anode foil of the aluminum electrolytic capacitor provided by the present disclosure adds a water-soluble pore-forming agent to the aluminum paste. The aluminum paste is coated on the surface of the aluminum foil substrate and dried to obtain an aluminum foil blank, then washed with water and dried to obtain a porous aluminum foil blank, and then through heat treatment and coating a protective film layer on the surface of the porous aluminum foil blank, a sintered foil with irregular multi-directional cracks on the surface and inside is obtained through rolling treatment and sintering. By adding a water-soluble pore-forming agent to the aluminum paste in this preparation method, the porosity of the aluminum foil blank can be increased, which is beneficial to the formation of internal stress in the aluminum foil blank during subsequent rolling treatment to form cracks during the sintering process; in addition, the surface and inside of the sintered foil obtained by this method have irregular multi-directional cracks, which can improve the anti-bending performance of the subsequent anode foil; in addition, in this preparation method, after coating the protective film layer on the surface of the porous aluminum foil blank first, and then performing skew rolling through a rolling mill, the problems of surface scratching, powder falling, and wrinkling of the anode foil can be solved. The protective film layer can form a gap between adjacent porous aluminum foil blanks to avoid adhesion between the porous aluminum foil blanks during subsequent sintering; in addition, the rolling rolls used in this preparation method are large-diameter rolls (with a diameter of 65 mm - 300 mm), and the stiffness of the rolls is better, which can effectively improve the problem of foil wrinkling caused by roll bending and improve the production quality of the anode foil. Through this preparation method, an anode foil with a flat surface and good anti-bending performance can be produced.

[0064] The following will describe in detail each step of the preparation method of the anode foil of the aluminum electrolytic capacitor provided by the embodiments of the present disclosure with reference to the accompanying drawings:

[0065] In the embodiments provided by the present disclosure, in step S1, an aluminum paste is prepared. The aluminum paste includes a mixed solution and solid aluminum-containing powder. The mixed solution is prepared by mixing a solvent, a binder, and an additive. The solid aluminum-containing powder includes aluminum powder and a water-soluble pore-forming agent.

[0066] Among them, the aluminum-containing slurry includes a mixed solution prepared by mixing a solvent, a binder, and an additive. The mass ratio of the solvent, the binder, and the additive in the mixed solution is 100:(3 - 10):(0.5 - 10). For example, the mass ratio of the three can be 100:3:0.5, 100:3:10, 100:10:0.5, or 100:10:10, etc. The mass ratio between the components in the mixed solution can be selected or adaptively adjusted according to the specific types and functions of the components.

[0067] The solvent is a mixture of a first solvent and a second solvent. The first solvent is one or two of terpineol and diethylene glycol butyl ether acetate. The second solvent is one or more of ethylene glycol, propylene glycol, and glycerol. The binder is one or two of ethyl cellulose and polyvinyl butyral. The additive includes one or more of an antifoaming agent, a leveling agent, a dispersant, and a coupling agent. The antifoaming agent is an organosilicon antifoaming agent or a polyether antifoaming agent. The leveling agent is an acrylate leveling agent. The dispersant is triethanolamine. The coupling agent is a silane coupling agent. By controlling the types and mass ratios of the components in the aluminum-containing slurry, the aluminum-containing slurry can have the characteristics of low evaporation rate, easy preservation, and moderate viscosity at room temperature. The solvent is easy to evaporate during the drying process, and the aluminum-containing slurry has good leveling property. There is no residue or little residue of the binder and the additive during the heat treatment process.

[0068] Among them, the aluminum-containing slurry includes solid aluminum-containing powder. The mass ratio of the mixed solution to the solid aluminum-containing powder is 100:(80 - 250). For example, the mass ratio between the two can be 100:80, 100:100, 100:120, 100:140, 100:160, 100:180, 100:200, 100:220, 100:240, or 100:250, etc. When the mass ratio between the mixed solution and the solid aluminum-containing powder is within the above range, the forming quality of the subsequent aluminum foil blank can be improved.

[0069] The solid aluminum-containing powder includes aluminum powder. The aluminum particles in the aluminum powder can be spherical or ellipsoidal. The particle size of the aluminum powder is 0.5 μm (micrometer) to 5 μm. For example, the particle size of the aluminum powder can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc. During the preparation of the aluminum powder, there can be various aluminum powders with different particle sizes in the solid aluminum-containing powder. In some exemplary embodiments, the particle sizes of the aluminum powders in the solid aluminum-containing powder can be the same or approximately the same. Among them, the mass purity of the aluminum powder is not less than 99.95%. For example, the mass purity of the aluminum powder can be 99.95%, 99.96%, 99.97%, 99.98%, or 99.99%, etc.

[0070] The solid aluminum-containing powder includes a water-soluble pore-forming agent. The mass fraction of the water-soluble pore-forming agent in the solid aluminum-containing powder is 0.5% to 4%. For example, the mass fraction of the water-soluble pore-forming agent in the solid aluminum-containing powder can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, or 4%, etc. The water-soluble pore-forming agent can be one or more of a water-soluble neutral salt, a water-soluble starch, and a water-soluble resin.

[0071] Among them, when the water-soluble pore-forming agent is a water-soluble neutral salt, the water-soluble pore-forming agent can be one or more of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate; when the water-soluble pore-forming agent is a water-soluble starch, the water-soluble pore-forming agent can be one or more of modified corn starch, modified potato starch, modified sweet potato starch, modified cassava starch, modified wheat starch, and modified mung bean starch; when the water-soluble pore-forming agent is a water-soluble resin, the water-soluble pore-forming agent can be one or more of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose.

[0072] By controlling the types and addition amounts of the components in the aluminum paste, the aluminum paste has the characteristics of low evaporation rate, easy storage, moderate viscosity, etc. at room temperature. The solvent is easy to volatilize during the drying process, and the slurry has good leveling property. The water-soluble pore-forming agent is easy to remove during the water washing process. The specific capacitance of the subsequent formed anode foil is relatively high, and there is no residue or little residue of the binder and additives during the subsequent heat treatment process.

[0073] In the embodiment provided by the present disclosure, in step S2, an aluminum foil substrate is provided, and the aluminum paste is coated on the surface of the aluminum foil substrate to form an aluminum foil blank, and the aluminum foil blank is dried.

[0074] Among them, the thickness of the aluminum foil substrate is 20 μm to 60 μm. For example, the thickness of the aluminum foil substrate can be 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm or 60 μm, etc. The aluminum foil substrate has an upper surface and a lower surface that are oppositely arranged. Since there may be subsequent differences between parts of the aluminum foil substrate, the thickness of the aluminum foil substrate can refer to one of the maximum distance, minimum distance or average distance between the upper surface and the lower surface. In the present disclosure, the thickness of the aluminum foil substrate is taken as the average distance between the upper surface and the lower surface as an example for illustration.

[0075] In some embodiments, in step S2, forming an aluminum foil blank includes: using an aluminum-containing slurry to perform double-sided coating on the aluminum foil substrate to form aluminum slurry film layers with the same thickness on the upper surface and the lower surface of the aluminum foil substrate; drying the aluminum foil substrate with the aluminum slurry film layers under the condition that the drying temperature is 90 °C to 200 °C.

[0076] Among them, the double-sided coating of the aluminum foil substrate can adopt coating methods such as knife coating and screen printing to form aluminum slurry film layers with the same thickness on the upper surface and the lower surface of the aluminum foil substrate. The thickness of the dried aluminum slurry film layer is 50 μm to 60 μm. For example, it can be 50 μm, 52 μm, 54 μm, 56 μm, 58 μm or 60 μm, etc. By controlling the thicknesses of the aluminum foil substrate and the aluminum slurry film layer, porous layers with appropriate thicknesses are formed on both sides of the aluminum foil blank, improving the ductility of the aluminum foil blank during the subsequent rolling process.

[0077] It should be noted that the same thickness of the aluminum slurry film layers formed on the upper surface and the lower surface of the aluminum foil substrate means that their thicknesses are exactly the same or approximately the same. Due to process errors, if the thickness difference between the two is within 1 μm, it can be considered that their thicknesses are the same.

[0078] After the aluminum slurry film layer is formed on the surface of the aluminum foil substrate, the aluminum foil substrate is dried. Among them, the drying temperature can be 90 °C to 200 °C. For example, the drying temperature can be 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C or 200 °C, etc. The specific drying temperature can be adaptively adjusted according to the thickness of the aluminum slurry film layer. For example, when the thickness of the aluminum slurry film layer is relatively thick, the drying temperature can be appropriately increased to shorten the drying time and improve the efficiency. This preparation method can control the drying temperature to make the slurry have good leveling property during the drying process and the solvent volatilize more thoroughly.

[0079] In the embodiments provided by the present disclosure, in step S3, the dried aluminum foil blank is washed with water and then dried to obtain a porous aluminum foil blank.

[0080] In some embodiments, step S3 includes: cleaning the aluminum foil blank with deionized water at a temperature of 10°C to 80°C, and the cleaning method is one of immersion or ultrasonic cleaning; drying the cleaned aluminum foil blank at a drying temperature of 40°C to 120°C.

[0081] Among them, the cleaning temperature is 10°C to 80°C. For example, it can be 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C, etc. By controlling the temperature of the deionized water, the water-soluble pore-forming agent can be removed and the formed aluminum foil blank is not likely to shed powder. The drying temperature is 40°C to 120°C. For example, it can be 40°C, 60°C, 80°C, 100°C or 120°C, etc. By controlling the drying temperature, the aluminum foil blank is easy to dry.

[0082] In the embodiments provided by the present disclosure, in step S4, the porous aluminum foil blank is heat-treated.

[0083] In some embodiments, the heat treatment in step S4 includes: in an air atmosphere, heating the porous aluminum foil blank from room temperature to 300°C to 500°C at a heating rate of 0.1°C / min to 20°C / min, and holding for 1 h to 8 h; in a nitrogen, argon or vacuum atmosphere, continuing to heat the porous aluminum foil blank to 570°C to 600°C at a heating rate of 0.1°C / min to 20°C / min, and holding for 4 h to 12 h; after the holding is completed, cooling with the furnace. Among them, the room temperature can be 20 to 25°C. By controlling the heating rate, holding temperature and holding time in the heat treatment process, the residual amounts of the binder and additives in the aluminum foil blank are reduced, or after heat treatment, there is no residue of the binder and additives in the aluminum foil blank.

[0084] In the embodiments provided by the present disclosure, in step S5, a thin film solution is coated on the surface of the heat-treated porous aluminum foil blank, and a drying treatment is performed to form a protective film layer on the surface of the porous aluminum foil blank.

[0085] Among them, the thin film solution is an aqueous solution prepared from one or more of hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone.

[0086] A thin film solution is coated on the surface of a porous aluminum foil blank. The method includes: using one of the forms of doctor blade coating or screen printing to perform double-sided coating of the thin film solution on the porous aluminum foil blank; the thickness of the protective film layer on each side of the porous aluminum foil blank is the same. The thickness of the protective film layer on each side of the porous aluminum foil blank is 5 μm to 30 μm. For example, the thickness of the protective film layer can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm, etc. The same thickness of the protective film layer on each side of the porous aluminum foil blank means that the thicknesses of the two protective film layers are exactly the same or approximately the same. Due to process errors, if the thickness difference between the two protective film layers is within 1 μm, it can be considered that their thicknesses are the same. By controlling the composition of the thin film solution and the thickness of the protective film layer, this method ensures that the protective film layer is not easily detached during subsequent rolling, protecting the aluminum paste film layer from being scratched and losing powder, and the protective film layer is relatively easy to remove during subsequent sintering without having an adverse impact on the overall structure of the anode foil.

[0087] In the embodiment provided by the present disclosure, in step S6, a rolling mill is used to perform rolling treatment on the porous aluminum foil blank with a protective film layer in an inclined rolling manner to obtain an initial anode foil.

[0088] The rolling mill can be one of a two-high rolling mill, a three-high rolling mill, or a four-high rolling mill. To improve the rolling quality of the rolling mill for the porous aluminum foil blank, the roll reduction of the rolling mill can be 5 μm to 15 μm. For example, the roll reduction of the rolling mill can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm, etc. To avoid phenomena such as powder loss or scratching of the porous aluminum foil blank during rolling, the roll diameter of the rolling mill can be 65 mm to 600 mm. For example, the roll diameter of the rolling mill can be 65 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, or 600 mm, etc.

[0089] In some embodiments, a rolling mill is used to perform rolling treatment on the porous aluminum foil blank with a protective film layer in an inclined rolling manner to obtain an initial anode foil. The method includes:

[0090] Perform the first rolling treatment on the porous aluminum foil blank with a protective film layer. The first rolling treatment is to repeatedly roll the porous aluminum foil blank 2 to 20 times when the axial direction of the roll is at an angle of 20° to 70° with the length direction of the aluminum foil blank; then perform the second rolling treatment on the porous aluminum foil blank with a protective film layer. The second rolling treatment is to repeatedly roll the porous aluminum foil blank 2 to 20 times when the axial direction of the roll is at an angle of 110° to 160° with the length direction of the aluminum foil blank.

[0091] Among them, in the first rolling process, the axial direction of the rolling mill rolls can form an angle of 20° to 70° with the length direction of the porous aluminum foil blank. For example, it can be 20°, 30°, 40°, 50°, 60° or 70°, etc., and the number of rolling passes can be 2 to 20 times; in the second rolling process, the axial direction of the rolling mill rolls forms an angle of 110° to 160° with the length direction of the porous aluminum foil blank. For example, it can be 110°, 120°, 130°, 140°, 150° or 160°, etc., and the number of rolling passes can be 2 to 20 times. In some exemplary embodiments, there is a correlation among the rolling angle of the rolling mill, the reduction of the rolling mill rolls, the diameter of the rolling mill rolls, and the number of rolling passes. When the diameter of the rolling mill rolls is relatively large, one or more of the reduction, rolling angle or number of rolling passes can be increased to improve the rolling efficiency and rolling quality.

[0092] By controlling the rolling angle of the rolling mill, the reduction of the rolling mill rolls, and the diameter of the rolling mill rolls, the protective film layer on the surface of the porous aluminum foil blank is not easily dropped during the rolling process, the aluminum paste film layer is not easily scratched and does not shed powder, and appropriate internal stress can be generated inside the aluminum paste film layer, so that irregular multi-directional cracks are generated in the aluminum paste film layer during the subsequent sintering process, thereby improving the anti-bending performance of the anode foil.

[0093] In the embodiment provided by the present disclosure, in step S7, the initial anode foil is sintered to remove the protective film layer to form a sintered foil.

[0094] Among them, sintering the initial anode foil includes: heating the initial anode foil from room temperature to 610°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 for 4h to 12h; after the holding is completed, it is cooled with the furnace.

[0095] Among them, the parameters of the sintering process are: in a nitrogen, argon or vacuum atmosphere, the heating rate is 0.1°C / min to 20°C / min. For example, the heating rate can be 0.1°C / min, 5°C / min, 10°C / min, 15°C / min or 20°C / min, etc.; the initial anode foil is heated from room temperature to the holding temperature, and the holding temperature is 610°C to 650°C. For example, the holding temperature can be 610°C, 620°C, 630°C, 640°C or 650°C, etc.; the holding time is 4h to 12h. For example, the holding time can be 4h, 6h, 8h, 10h or 12h, etc. In the embodiment provided by the present disclosure, the room temperature can be 20°C to 25°C.

[0096] By adjusting and controlling parameters such as the heating rate, sintering atmosphere, holding temperature, and holding time of the sintering process, the protective film layer on the surface of the sintered foil can be completely removed, while keeping the surface of the sintered foil flat and non-sticky, ensuring the flatness and integrity of the surface of the sintered foil, and irregular multi-directional cracks can be generated on the surface and inside of the sintered foil to improve the anti-bending performance of the subsequent formed anode foil.

[0097] In the embodiment provided by the present disclosure, after step S7, the method further includes: performing a water boiling treatment on the sintered foil to form an intermediate anode foil; performing a forming treatment on the intermediate anode foil to form an oxide layer on the intermediate anode foil to obtain a target anode foil; performing a cleaning and drying treatment on the target anode foil.

[0098] Among them, the water boiling treatment includes boiling the sintered foil in deionized water at 100°C for 5 min to 15 min. Among them, the temperature of the deionized water can be strictly 100°C, but due to temperature errors, the temperature of the deionized water can also be in the range of 100°C ± 1°C, and both can be considered as the temperature of the deionized water required during the water boiling treatment. The time of the water boiling treatment is 5 min to 15 min. For example, it can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min, etc.

[0099] By adjusting and controlling the time and temperature of the water boiling treatment, a hydrated alumina layer with a suitable thickness can be formed on the surface of the aluminum powder particles in the sintered foil, which is beneficial to forming an oxide layer during the subsequent forming treatment.

[0100] Among them, the forming treatment includes performing a forming treatment on the intermediate anode foil under the condition that the forming voltage is 200 V to 700 V. Among them, the forming voltage is 200 V to 700 V. For example, the forming voltage can be 200 V, 300 V, 400 V, 500 V, 600 V, or 700 V, etc. Through the forming treatment, the hydrated alumina layer can be converted into an oxide layer, and among them, the oxide layer is an alumina film layer.

[0101] By adjusting and controlling the forming voltage, anode foils with various rated withstand voltage requirements can be produced.

[0102] Performing a cleaning and drying treatment on the target anode foil to obtain a target anode foil with better cleanliness.

[0103] The embodiment of the present disclosure also provides an aluminum electrolytic capacitor, which includes an anode foil prepared by the above method, and the capacitor has good mechanical properties and good overall device performance.

[0104] The following further illustrates the method for preparing the anode foil provided by the present disclosure through specific examples:

[0105] Control Example 1

[0106] Step 1: Mix the solvent (diethylene glycol butyl ether acetate and propylene glycol), binder (polyvinyl butyral), and additives (polyether defoamer and acrylate leveling agent) evenly by stirring at a mass ratio of 80:20:5:0.5:3 to obtain a mixed solution. Mix the mixed solution with solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) evenly by stirring at a mass ratio of 100:150 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 1%.

[0107] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 50 μm each.

[0108] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 50 °C; the washing method is soaking; the drying temperature is 80 °C.

[0109] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 400 °C in air at a heating rate of 10 °C / min and hold for 4 h; then heat to 580 °C in vacuum at a heating rate of 10 °C / min and hold for 8 h, and after the holding ends, cool with the furnace.

[0110] Step 5: Process cracks on the surface of the heat-treated aluminum foil obtained in Step 4 through a roller with a diameter of 12 mm. The process is as follows: first pass the aluminum foil through the roller with the length direction of the aluminum foil at an angle of 20° to the axis direction of the roller and repeat passing 20 times, then pass the aluminum foil through the roller with the length direction of the aluminum foil at an angle of 140° to the axis direction of the roller and repeat passing 20 times.

[0111] Step 6: Sinter the aluminum foil obtained in Step 5. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: heat to 630 °C in argon at a heating rate of 10 °C / min and hold for 8 h, and after the holding ends, cool with the furnace.

[0112] Step 7: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 6, wash it with deionized water, and dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 15 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 520 V.

[0113] Control Example 2

[0114] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate and propylene glycol), binder (polyvinyl butyral), additives (polyether defoamer and acrylate leveling agent) in a mass ratio of 80:20:5:0.5:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride and modified corn starch) in a mass ratio of 100:150 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm and the mass purity is 99.99%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 1%.

[0115] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 30 μm, and the dried thickness of the aluminum paste coated on both the upper surface and the lower surface is 50 μm.

[0116] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 50 °C; the washing method is immersion; the drying temperature is 80 °C.

[0117] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 400 °C in air at a heating rate of 10 °C / min and hold for 4 h; then heat to 580 °C in vacuum at a heating rate of 10 °C / min and hold for 8 h, and cool with the furnace after the holding ends.

[0118] Step 5: Process cracks on the surface of the foil of the heat-treated aluminum foil obtained in Step 4 through a roller (with a diameter of 12 mm) whose circumferential surface is provided with balls (with a diameter of 2 mm) that can rotate around their own spherical centers. The process is as follows: First, pass the aluminum foil through the roller with the length direction of the aluminum foil at an angle of 20° to the axis direction of the roller, and repeat passing 20 times; then pass the aluminum foil through the roller with the length direction of the aluminum foil at an angle of 140° to the axis direction of the roller, and repeat passing 20 times.

[0119] Step 6: Sinter the aluminum foil obtained in Step 5. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat to 630 °C in argon at a heating rate of 10 °C / min and hold for 8 h, and cool with the furnace after the holding ends.

[0120] Step 7: Subject the sintered foil obtained in Step 6 to water boiling treatment and formation treatment. After washing with deionized water, dry it at 100 °C to obtain the anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 15 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 520 V.

[0121] Control Example 3

[0122] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate and propylene glycol), binder (polyvinyl butyral), additives (polyether defoamer and acrylate leveling agent) in a mass ratio of 80:20:5:0.5:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) in a mass ratio of 100:150 to obtain aluminum paste (also referred to as slurry in the following examples); among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 1%.

[0123] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 30 μm, and the dried thickness of the aluminum paste coated on both the upper and lower surfaces is 50 μm.

[0124] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 50 °C; the washing method is immersion; the drying temperature is 80 °C.

[0125] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 400 °C in air at a heating rate of 10 °C / min and hold for 4 h; then heat to 580 °C in vacuum at a heating rate of 10 °C / min and hold for 8 h, and after the holding ends, cool with the furnace.

[0126] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a thin film solution and dry it. The thin film solution is ethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the thin film thickness is 15 μm.

[0127] Step 6: Sinter the aluminum foil with a protective film layer obtained in Step 5. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: heat to 630 °C in argon at a heating rate of 10 °C / min and hold for 8 h, and after the holding ends, cool with the furnace.

[0128] Step 7: Subject the sintered foil obtained in Step 6 to water boiling treatment and formation treatment. After cleaning with deionized water, dry it at 100°C to obtain the anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 15 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 520 V.

[0129] Example 1

[0130] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate and propylene glycol), binder (polyvinyl butyral), additives (polyether defoamer and acrylate leveling agent) in a mass ratio of 80:20:5:0.5:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 1%.

[0131] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is both 50 μm.

[0132] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 50°C; the washing method is soaking; the drying temperature is 80°C.

[0133] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 400°C in air at a heating rate of 10°C / min and hold for 4 h; then heat to 580°C in vacuum at a heating rate of 10°C / min and hold for 8 h, and after the holding ends, cool with the furnace.

[0134] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is ethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the film thickness is 15 μm.

[0135] Step 6: Roll the aluminum foil with a protective film layer obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer 20 times with the length direction of the aluminum foil at an angle of 20° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer 20 times with the length direction of the aluminum foil at an angle of 140° to the axis direction of the roll; the roll reduction (also referred to as the reduction in the following embodiments) during the rolling process is 5 μm; the roll diameter is 300 mm; the rolling mill is a two-high rolling mill.

[0136] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat it to 630 °C at a heating rate of 10 °C / min in argon, hold for 8 h, and then cool it with the furnace after the holding ends.

[0137] Step 8: Perform water boiling treatment and forming treatment on the sintered foil obtained in Step 7. After cleaning with deionized water, dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 15 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 520 V.

[0138] When performing the folding strength test using a chuck with a curvature radius of 3.5 mm, the number of longitudinal folding times of the anode foil obtained in Comparative Example 1 is 118 times, the number of transverse folding times is 66 times, and the static specific capacitance is 0.926 μF / cm2; the number of longitudinal folding times of the anode foil obtained in Comparative Example 2 is 124 times, the number of transverse folding times is 58 times, and the static specific capacitance is 0.934 μF / cm2; the number of longitudinal folding times of the anode foil obtained in Comparative Example 3 is 5 times, the number of transverse folding times is 9 times, and the static specific capacitance is 0.956 μF / cm2; the number of longitudinal folding times of the anode foil obtained in Example 1 is 136 times, the number of transverse folding times is 72 times, and the static specific capacitance is 0.951 μF / cm2; under the same number of treatment times, the performance (static specific capacitance and folding times) of the anode foil prepared in Example 1 is higher than that of the anode foils prepared in Comparative Example 1 and Comparative Example 2.

[0139] In addition, Figure 2 、 Figure 3 and Figure 4 are respectively the optical microscope images of the anode foils obtained by using the preparation methods provided in Comparative Example 1, Comparative Example 2, and Example 1. From Figure 2 and Figure 3 it can be seen that the anode foils obtained in Comparative Example 1 and Comparative Example 2 both have irregular multi-directional cracks, but there are defects such as scratches and powder falling on the surface of the anode foils; from Figure 4It can be seen that the anode foil obtained in Example 1 has irregular multi-directional cracks, and the surface quality of the anode foil is good, without defects such as scratches and powder shedding. The preparation method of Example 1 can obtain an anode foil with better anti-bending performance.

[0140] Control Example 4

[0141] Step 1: Mix and stir evenly a solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), a binder (ethyl cellulose and polyvinyl butyral), and additives (a polyether defoamer, an acrylate leveling agent, a triethanolamine dispersant, and a silane coupling agent) in a mass ratio of 40:30:10:10:10:5:5:1:1:5:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and solid aluminum-containing powder (aluminum powder and water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:80 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fraction of potassium sulfate in the solid aluminum-containing powder is 0.5%.

[0142] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 90 °C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 50 μm.

[0143] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 10 °C; the washing method is immersion; the drying temperature is 120 °C.

[0144] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace. The heat treatment process is as follows: First, heat from room temperature to 300 °C in air at a heating rate of 20 °C / min and hold for 8 h; then heat to 570 °C in argon at a heating rate of 20 °C / min and hold for 12 h. After the holding ends, cool with the furnace.

[0145] Step 5: Coat and dry a thin film solution on the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4. The thin film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is screen printing; the film thickness is 5 μm.

[0146] Step 6: Sinter the aluminum foil with a protective film layer obtained in Step 5. The sintering is carried out in a bell-type furnace. The sintering process is as follows: Heat to 650 °C in vacuum at a heating rate of 0.1 °C / min, hold for 2 h, and after the holding ends, cool with the furnace.

[0147] Step 7: Subject the sintered foil obtained in Step 6 to water boiling treatment and formation treatment. After cleaning with deionized water, dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 5 min; the formation treatment uses a boric acid solution of 100 g / L, and the formation voltage is 520 V.

[0148] Example 2

[0149] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), binder (ethyl cellulose and polyvinyl butyral), additives (polyether defoamer, acrylate leveling agent, triethanolamine dispersant, and silane coupling agent) in a mass ratio of 40:30:10:10:10:5:5:1:1:5:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and solid aluminum-containing powder (aluminum powder and water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:80 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fraction of potassium sulfate in the solid aluminum-containing powder is 0.5%.

[0150] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 90 °C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on both the upper surface and the lower surface after drying is 50 μm.

[0151] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 10 °C; the washing method is soaking; the drying temperature is 120 °C.

[0152] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace. The heat treatment process is as follows: First, heat from room temperature to 300 °C in air at a heating rate of 20 °C / min and hold for 8 h; then heat to 570 °C in argon at a heating rate of 20 °C / min and hold for 12 h. After the holding ends, cool it with the furnace.

[0153] Step 5: Coat the upper surface and the lower surface of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is screen printing; the film thickness is 5 μm.

[0154] Step 6: Roll the aluminum foil with a protective film layer obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer 2 times when the length direction of the aluminum foil is at an angle of 70° with the axis direction of the roll, and then roll the aluminum foil with a protective film layer 2 times when the length direction of the aluminum foil is at an angle of 110° with the axis direction of the roll; the reduction in the rolling process is 15 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0155] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat it to 650 °C at a heating rate of 0.1 °C / min in a vacuum, hold for 2 h, and then cool it with the furnace after the holding ends.

[0156] Step 8: Perform boiling water treatment and chemical conversion treatment on the sintered foil obtained in Step 7. After cleaning with deionized water, dry it at 100 °C to obtain an anode foil. Among them, the boiling water treatment uses deionized water at 100 °C, and the boiling water treatment time is 5 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 520 V.

[0157] When performing the bending strength test using a chuck with a radius of curvature of 3.5 mm, the number of longitudinal bends of the anode foil obtained in Comparative Example 4 is 1 time, the number of transverse bends is 3 times, and the static specific capacitance is 1.002 μF / cm 2 ; the number of longitudinal bends of the anode foil obtained in Example 2 is 179 times, the number of transverse bends is 69 times, and the static specific capacitance is 0.998 μF / cm 2 .

[0158] Comparative Example 5

[0159] Step 1: Mix and stir evenly the solvent (terpineol and ethylene glycol), the binder ethyl cellulose, and the additive silicone defoamer in a mass ratio of 50:50:3:0.5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) in a mass ratio of 100:250 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 2.5%, 1%, and 0.5% respectively.

[0160] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 200 °C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on the upper surface and the lower surface after drying is 50 μm.

[0161] Step 3: Wash and dry the aluminum foil blank obtained in Step 2. The washing process is to clean the aluminum foil blank with deionized water at 80°C; the cleaning method is ultrasonic cleaning; the drying temperature is 40°C.

[0162] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 500°C in air at a heating rate of 0.1°C / min and hold for 1 h; then heat to 600°C in nitrogen at a heating rate of 0.1°C / min and hold for 4 h, and then cool with the furnace after the holding ends.

[0163] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a thin film solution and dry. The thin film solution is a polyethylene glycol solution; the coating method is doctor blade coating; the film thickness is 30 μm.

[0164] Step 6: Sinter the aluminum foil with a protective film layer obtained in Step 5. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat to 610°C in nitrogen at a heating rate of 20°C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0165] Step 7: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 6, wash with deionized water, and dry at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 10 min; the formation treatment uses a boric acid solution of 100 g / L, and the formation voltage is 520 V.

[0166] Example 3

[0167] Step 1: Mix and stir evenly the solvent (terpineol and ethylene glycol), the binder ethyl cellulose, and the additive silicone defoamer in a mass ratio of 50:50:3:0.5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) in a mass ratio of 100:250 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 2.5%, 1%, and 0.5% respectively.

[0168] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a doctor blade and dry; after turning 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a doctor blade and dry to obtain an aluminum foil blank. The drying temperature is 200°C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 50 μm.

[0169] Step 3: Wash and dry the aluminum foil blank obtained in Step 2. The washing process is to clean the aluminum foil blank with deionized water at 80°C; the cleaning method is ultrasonic cleaning; the drying temperature is 40°C.

[0170] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 500°C in air at a heating rate of 0.1°C / min and hold for 1 h; then heat to 600°C in nitrogen at a heating rate of 0.1°C / min and hold for 4 h, and then cool with the furnace after the holding ends.

[0171] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a thin film solution and dry it. The thin film solution is a polyethylene glycol solution; the coating method is doctor blade coating; the film thickness is 30 μm.

[0172] Step 6: Roll the aluminum foil with a protective film layer on the surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 40° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 160° to the axis direction of the roll; the reduction in the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a four-high rolling mill.

[0173] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat to 610°C in nitrogen at a heating rate of 20°C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0174] Step 8: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 7, wash it with deionized water, and dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 10 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 520 V.

[0175] When the flexural strength test is carried out using a chuck with a curvature radius of 3.5 mm, the number of longitudinal bends of the anode foil obtained in Comparative Example 5 is 14 times, the number of transverse bends is 15 times, and the static specific capacitance is 0.922 μF / cm 2 ; the number of longitudinal bends of the anode foil obtained in Example 3 is 169 times, the number of transverse bends is 98 times, and the static specific capacitance is 0.919 μF / cm 2 .

[0176] Comparative Example 6

[0177] Step 1: Mix the solvent (terpineol, diethylene glycol butyl ether acetate, and ethylene glycol), the binder polyvinyl butyral, and the additives (silicone defoamer and triethanolamine dispersant) evenly by stirring at a mass ratio of 40:20:40:3:0.5:2 to obtain a mixed solution. Mix the mixed solution with the solid aluminum-containing powder (aluminum powder and water-soluble pore-forming agent potassium chloride) evenly by stirring at a mass ratio of 100:250 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fraction of potassium chloride in the solid aluminum-containing powder is 4%.

[0178] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the aluminum paste coated on both the upper and lower surfaces after drying is 60 μm.

[0179] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 80 °C; the washing method is soaking; the drying temperature is 50 °C.

[0180] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 450 °C in air at a heating rate of 1 °C / min and hold for 1 h; then heat to 600 °C in vacuum at a heating rate of 1 °C / min and hold for 4 h, and after the holding ends, cool with the furnace.

[0181] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is ethyl cellulose; the coating method is screen printing; the film thickness is 20 μm.

[0182] Step 6: Sinter the aluminum foil with a protective film layer on the surface obtained in Step 5. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat to 650 °C in vacuum at a heating rate of 1 °C / min and hold for 4 h, and after the holding ends, cool with the furnace.

[0183] Step 7: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 6, wash it with deionized water, and dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 15 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 200 V.

[0184] Example 4

[0185] Step 1: Mix and stir evenly a solvent (terpineol, diethylene glycol butyl ether acetate, and ethylene glycol), a binder polyvinyl butyral, and additives (an organosilicon defoamer and a triethanolamine dispersant) in a mass ratio of 40:20:40:3:0.5:2 to obtain a mixed solution. Mix and stir evenly the mixed solution and a solid aluminum-containing powder (aluminum powder and a water-soluble pore-forming agent potassium chloride) in a mass ratio of 100:250 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fraction of potassium chloride in the solid aluminum-containing powder is 4%.

[0186] Step 2: Coat the slurry obtained in Step 1 on the upper surface of an aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the aluminum paste coated on both the upper surface and the lower surface after drying is 60 μm.

[0187] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 80 °C; the washing method is soaking; the drying temperature is 50 °C.

[0188] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 450 °C at a heating rate of 1 °C / min in air and hold for 1 h; then heat to 600 °C at a heating rate of 1 °C / min in vacuum and hold for 4 h, and after the holding ends, cool with the furnace.

[0189] Step 5: Coat a thin film solution on the upper surface and the lower surface of the heat-treated aluminum foil obtained in Step 4 and dry it. The thin film solution is ethyl cellulose; the coating method is screen printing; the thin film thickness is 20 μm.

[0190] Step 6: Roll the aluminum foil with a protective film layer on the surface obtained in Step 5. The rolling is skew rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 40° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 140° to the axis direction of the roll; the reduction in the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a three-roll rolling mill.

[0191] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat to 650 °C at a heating rate of 1 °C / min in vacuum, hold for 4 h, and after the holding ends, cool with the furnace.

[0192] Step 8: Subject the sintered foil obtained in Step 7 to water boiling treatment and formation treatment. After cleaning with deionized water, dry it at 100°C to obtain the anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 15 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 200 V.

[0193] When performing the folding strength test using a chuck with a curvature radius of 3.5 mm, the number of longitudinal bends of the anode foil obtained in Comparative Example 6 is 12 times, the number of transverse bends is 16 times, and the static specific capacitance is 2.914 μF / cm 2 ; the number of longitudinal bends of the anode foil obtained in Example 4 is 141 times, the number of transverse bends is 91 times, and the static specific capacitance is 2.892 μF / cm 2 .

[0194] Comparative Example 7

[0195] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, propylene glycol), the binder ethyl cellulose, and the additives (organosilicon defoamer and acrylate leveling agent) in a mass ratio of 50:30:20:5:0.5:0.5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 1%.

[0196] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 60 μm.

[0197] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 60°C; the washing method is ultrasonic cleaning; the drying temperature is 70°C.

[0198] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 350°C in air at a heating rate of 5°C / min and hold for 6 h; then heat to 580°C in vacuum at a heating rate of 10°C / min and hold for 12 h, and after the holding ends, cool with the furnace.

[0199] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl butyral and polyvinylpyrrolidone; the coating method is blade coating; the film thickness is 15 μm.

[0200] Step 6: Sinter the aluminum foil with a protective film layer obtained in Step 5. The sintering is carried out in a bell furnace, and the sintering process is as follows: heat it to 630 °C at a heating rate of 5 °C / min in argon, hold for 6 h, and then cool it with the furnace after the holding ends.

[0201] Step 7: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 6. After cleaning with deionized water, dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 10 min; the chemical conversion treatment uses a boric acid solution of 100 g / L, and the chemical conversion voltage is 200 V.

[0202] Example 5

[0203] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, propylene glycol), binder ethyl cellulose, additives (organosilicon defoamer and acrylate leveling agent) in a mass ratio of 50:30:20:5:0.5:0.5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride and modified corn starch) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 1%.

[0204] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a blade and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a blade and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 20 μm, and the dried thickness of the aluminum paste coated on the upper and lower surfaces is both 60 μm.

[0205] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 60 °C; the washing method is ultrasonic cleaning; the drying temperature is 70 °C.

[0206] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace, and the heat treatment process is as follows: first heat it from room temperature to 350 °C at a heating rate of 5 °C / min in air, hold for 6 h; then heat it to 580 °C at a heating rate of 10 °C / min in vacuum, hold for 12 h, and then cool it with the furnace after the holding ends.

[0207] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl butyral and polyvinylpyrrolidone; the coating method is knife coating; the film thickness is 15 μm.

[0208] Step 6: Roll the aluminum foil with a protective film layer on its surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on its surface 20 times with the length direction of the aluminum foil at an angle of 30° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on its surface 20 times with the length direction of the aluminum foil at an angle of 150° to the axis direction of the roll; the reduction in the rolling process is 15 μm; the roll diameter is 300 mm; the rolling mill is a two-high rolling mill.

[0209] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat it to 630 °C at a heating rate of 5 °C / min in argon, hold for 6 h, and then cool it with the furnace after the holding ends.

[0210] Step 8: Perform water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 7, wash it with deionized water, and dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 10 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 200 V.

[0211] When performing the folding strength test with a chuck having a curvature radius of 3.5 mm, the number of longitudinal folds of the anode foil obtained in Comparative Example 7 is 7 times, the number of transverse folds is 8 times, and the static specific capacitance is 2.941 μF / cm 2 ; the number of longitudinal folds of the anode foil obtained in Example 5 is 175 times, the number of transverse folds is 75 times, and the static specific capacitance is 2.939 μF / cm 2 .

[0212] Comparative Example 8

[0213] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, glycerol), binder (ethyl cellulose and polyvinyl butyral), and additives (polyether defoamer, triethanolamine dispersant, and silane coupling agent) in a mass ratio of 40:30:25:5:3:5:1:1:4 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) in a mass ratio of 100:80 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 0.2%, 0.2%, and 0.1% respectively.

[0214] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it. After turning it over by 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 200°C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the aluminum paste coated on both the upper and lower surfaces after drying is 60 μm.

[0215] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 30°C; the washing method is ultrasonic cleaning; the drying temperature is 110°C.

[0216] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace, and the heat treatment process is as follows: First, heat from room temperature to 300°C in air at a heating rate of 10°C / min and hold for 8 h; then heat to 570°C in argon at a heating rate of 5°C / min and hold for 6 h, and then cool with the furnace after the holding ends.

[0217] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose; the coating method is screen printing; the film thickness is 10 μm.

[0218] Step 6: Sinter the aluminum foil with a protective film layer on the surface obtained in Step 5. The sintering is carried out in a bell furnace, and the sintering process is as follows: Heat to 610°C in argon at a heating rate of 20°C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0219] Step 7: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 6. After washing with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 5 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 200 V.

[0220] Example 6

[0221] Step 1: Mix the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, glycerol), binder (ethyl cellulose and polyvinyl butyral), and additives (polyether defoamer, triethanolamine dispersant, and silane coupling agent) evenly by stirring at a mass ratio of 40:30:25:5:3:5:1:1:4 to obtain a mixed solution. Mix the mixed solution with solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) evenly by stirring at a mass ratio of 100:80 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 0.2%, 0.2%, and 0.1% respectively.

[0222] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 200 °C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the dried aluminum paste coated on both the upper surface and the lower surface is 60 μm.

[0223] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 30 °C; the washing method is ultrasonic cleaning; the drying temperature is 110 °C.

[0224] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace, and the heat treatment process is as follows: first heat from room temperature to 300 °C in air at a heating rate of 10 °C / min and hold for 8 h; then heat to 570 °C in argon at a heating rate of 5 °C / min and hold for 6 h, and after the holding ends, cool with the furnace.

[0225] Step 5: Coat the upper surface and the lower surface of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose; the coating method is screen printing; the film thickness is 10 μm.

[0226] Step 6: Roll the aluminum foil with a protective film layer on its surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: first roll the aluminum foil with a protective film layer on its surface 2 times with the length direction of the aluminum foil at an angle of 60° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on its surface 2 times with the length direction of the aluminum foil at an angle of 120° to the axis direction of the roll; the reduction in the rolling process is 15 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0227] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell furnace, and the sintering process is as follows: heat to 610 °C in argon at a heating rate of 20 °C / min and hold for 12 h, and after the holding ends, cool with the furnace.

[0228] Step 8: Subject the sintered foil obtained in Step 7 to water boiling treatment and formation treatment. After washing with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 5 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 200 V.

[0229] When performing the bending strength test using a chuck with a curvature radius of 3.5 mm, the number of longitudinal bends of the anode foil obtained in Comparative Example 8 is 4 times, the number of transverse bends is 3 times, and the static specific capacitance is 3.054 μF / cm 2 ; the number of longitudinal bends of the anode foil obtained in Example 6 is 185 times, the number of transverse bends is 92 times, and the static specific capacitance is 3.051 μF / cm 2 .

[0230] Comparative Example 9

[0231] Step 1: Mix and stir evenly a solvent (diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), a binder ethyl cellulose, and additives (an organic silicon defoamer and a silane coupling agent) in a mass ratio of 30:30:30:10:8:0.5:5 to obtain a mixed solution. Mix and stir evenly the mixed solution and a solid aluminum-containing powder (aluminum powder and a water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:250 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 2%.

[0232] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is both 55 μm.

[0233] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 80°C; the washing method is immersion; the drying temperature is 60°C.

[0234] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 500°C in air at a heating rate of 15°C / min and hold for 4 h; then heat to 600°C in nitrogen at a heating rate of 3°C / min and hold for 4 h, and after the holding ends, cool with the furnace.

[0235] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl butyral; the coating method is blade coating; the film thickness is 30 μm.

[0236] Step 6: Sinter the aluminum foil with a protective film layer obtained in Step 5. The sintering is carried out in a bell furnace, and the sintering process is as follows: Heat it to 610 °C at a heating rate of 5 °C / min in a vacuum, hold for 12 h, and then cool it with the furnace after the holding ends.

[0237] Step 7: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 6. After cleaning with deionized water, dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 10 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 700 V.

[0238] Example 7

[0239] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), the binder ethyl cellulose, and the additives (organic silicon defoamer and silane coupling agent) in a mass ratio of 30:30:30:10:8:0.5:5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder and water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:250 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 2%.

[0240] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a blade and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a blade and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 55 μm.

[0241] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 80 °C; the washing method is soaking; the drying temperature is 60 °C.

[0242] Step 4: Carry out heat treatment on the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace, and the heat treatment process is as follows: First, heat it from room temperature to 500 °C at a heating rate of 15 °C / min in the air, hold for 4 h; then heat it to 600 °C at a heating rate of 3 °C / min in nitrogen, hold for 4 h, and then cool it with the furnace after the holding ends.

[0243] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl butyral; the coating method is blade coating; the film thickness is 30 μm.

[0244] Step 6: Roll the aluminum foil with a protective film layer on its surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on its surface 10 times with the length direction of the aluminum foil at a 45° angle to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on its surface 10 times with the length direction of the aluminum foil at a 135° angle to the axis direction of the roll; the reduction in the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a three-roll rolling mill.

[0245] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat it to 610 °C at a heating rate of 5 °C / min in a vacuum, hold for 12 h, and then cool it with the furnace after the holding ends.

[0246] Step 8: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 7. After cleaning with deionized water, dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 10 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 700 V.

[0247] When performing the folding strength test using a chuck with a curvature radius of 3.5 mm, the number of longitudinal folding times of the anode foil obtained in Comparative Example 9 is 17 times, the number of transverse folding times is 14 times, and the static specific capacitance is 0.776 μF / cm 2 ; the number of longitudinal folding times of the anode foil obtained in Example 7 is 149 times, the number of transverse folding times is 109 times, and the static specific capacitance is 0.771 μF / cm 2 .

[0248] Comparative Example 10

[0249] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate, propylene glycol, and glycerol), the binder polyvinyl butyral, and the additives (organic silicon defoamer and acrylate leveling agent) in a mass ratio of 90:5:5:5:1:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are 1.5% and 0.5% respectively.

[0250] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it. After turning it over by 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 60 μm, and the dried thickness of the aluminum paste coated on both the upper and lower surfaces is 55 μm.

[0251] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 50°C; the washing method is immersion; the drying temperature is 80°C.

[0252] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace. The heat treatment process is as follows: First, heat from room temperature to 450°C in air at a heating rate of 3°C / min and hold for 6 h; then heat to 580°C in vacuum at a heating rate of 15°C / min and hold for 10 h, and then cool with the furnace after the holding ends.

[0253] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a thin film solution and dry it. The thin film solution is polyvinyl alcohol and hydroxypropyl methylcellulose; the coating method is screen printing; the thickness of the thin film is 20 μm.

[0254] Step 6: Sinter the aluminum foil with a protective film layer on its surface obtained in Step 5. The sintering is carried out in a bell-type furnace. The sintering process is as follows: Heat to 640°C in argon at a heating rate of 10°C / min and hold for 6 h, and then cool with the furnace after the holding ends.

[0255] Step 7: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 6. After washing with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C and the water boiling time is 5 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L and the forming voltage is 700 V.

[0256] Example 8

[0257] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate, propylene glycol, and glycerol), the binder polyvinyl butyral, and the additives (organic silicone defoamer and acrylate leveling agent) in a mass ratio of 90:5:5:5:1:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm and the mass purity is 99.95%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are 1.5% and 0.5% respectively.

[0258] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a doctor blade, and then dry it. After turning it over by 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a doctor blade and dry it to obtain an aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on both the upper and lower surfaces after drying is 55 μm.

[0259] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and then dry it. The water washing process is to wash the aluminum foil blank with deionized water at 50°C; the washing method is immersion; the drying temperature is 80°C.

[0260] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat it from room temperature to 450°C in air at a heating rate of 3°C / min and hold for 6 h; then heat it to 580°C in vacuum at a heating rate of 15°C / min and hold for 10 h, and after the holding ends, cool it with the furnace.

[0261] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and then dry it. The film solution is polyvinyl alcohol and hydroxypropyl methylcellulose; the coating method is screen printing; the film thickness is 20 μm.

[0262] Step 6: Roll the aluminum foil with a protective film layer on its surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on its surface 20 times with the length direction of the aluminum foil at an angle of 20° to the axis direction of the roll, and then roll it 20 times with the length direction of the aluminum foil at an angle of 110° to the axis direction of the roll; the reduction in the rolling process is 5 μm; the roll diameter is 300 mm; the rolling mill is a two-high rolling mill.

[0263] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat it to 640°C in argon at a heating rate of 10°C / min and hold for 6 h, and after the holding ends, cool it with the furnace.

[0264] Step 8: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 7. After washing with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 5 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 700 V.

[0265] When the folding strength test is carried out using a chuck with a curvature radius of 3.5 mm, the number of longitudinal folding times of the anode foil obtained in Comparative Example 10 is 8 times, the number of transverse folding times is 12 times, and the static specific capacitance is 0.788 μF / cm 2; The longitudinal folding times of the anode foil obtained in Example 8 were 143 times, the transverse folding times were 55 times, and the static specific capacitance was 0.781 μF / cm 2 .

[0266] Control Example 11

[0267] Step 1: Mix the solvent (diethylene glycol butyl ether acetate, ethylene glycol, and glycerol), binder (ethyl cellulose and polyvinyl butyral), and additives (polyether defoamer, acrylate leveling agent, dispersant triethanolamine, and silane coupling agent) evenly by stirring at a mass ratio of 50:40:10:3:7:1:1:2:6 to obtain a mixed solution. Mix the mixed solution with solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, polyethylene glycol) evenly by stirring at a mass ratio of 100:80 to obtain a slurry; where the particle size of the aluminum powder is 0.5 μm to 5 μm and the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 0.2%, 0.1%, and 0.2% respectively.

[0268] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 90 °C, the thickness of the aluminum foil substrate is 60 μm, and the dried thickness of the aluminum paste coated on the upper and lower surfaces is 55 μm each.

[0269] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 10 °C; the washing method is ultrasonic cleaning; the drying temperature is 100 °C.

[0270] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace, and the heat treatment process is as follows: First, heat from room temperature to 500 °C in air at a heating rate of 20 °C / min and hold for 8 h; then heat to 570 °C in argon at a heating rate of 20 °C / min and hold for 6 h, and then cool with the furnace after the holding ends.

[0271] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is scraper coating; the film thickness is 25 μm.

[0272] Step 6: Sinter the aluminum foil with a protective film layer on the surface obtained in Step 5. The sintering is carried out in a bell furnace, and the sintering process is as follows: Heat to 650 °C in nitrogen at a heating rate of 0.1 °C / min and hold for 4 h, and then cool with the furnace after the holding ends.

[0273] Step 7: Subject the sintered foil obtained in Step 6 to water boiling treatment and formation treatment. After cleaning with deionized water, dry it at 100 °C to obtain the anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 15 min; the formation treatment uses a boric acid solution of 100 g / L, and the formation voltage is 700 V.

[0274] Example 9

[0275] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate, ethylene glycol, and glycerol), binder (ethyl cellulose and polyvinyl butyral), additives (polyether defoamer, acrylate leveling agent, dispersant triethanolamine, and silane coupling agent) in a mass ratio of 50:40:10:3:7:1:1:2:6 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, polyethylene glycol) in a mass ratio of 100:80 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, and the mass purity is 99.99%. The mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 0.2%, 0.1%, and 0.2% respectively.

[0276] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 90 °C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on both the upper surface and the lower surface after drying is 55 μm.

[0277] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 10 °C; the washing method is ultrasonic cleaning; the drying temperature is 100 °C.

[0278] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace. The heat treatment process is as follows: First, heat from room temperature to 500 °C in air at a heating rate of 20 °C / min and hold for 8 h; then heat to 570 °C in argon at a heating rate of 20 °C / min and hold for 6 h. After the holding ends, cool with the furnace.

[0279] Step 5: Coat the upper surface and the lower surface of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is scraper coating; the film thickness is 25 μm.

[0280] Step 6: Roll the aluminum foil with a protective film layer obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer 2 times with the length direction of the aluminum foil at an angle of 70° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer 2 times with the length direction of the aluminum foil at an angle of 160° to the axis direction of the roll; the reduction in the rolling process is 10 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0281] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat in nitrogen at a heating rate of 0.1 °C / min to 650 °C, hold for 4 h, and then cool with the furnace after the holding ends.

[0282] Step 8: Perform water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 7. After cleaning with deionized water, dry at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 15 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 700 V.

[0283] When performing the bending strength test with a chuck having a radius of curvature of 3.5 mm, the number of longitudinal bends of the anode foil obtained in Comparative Example 11 is 3 times, the number of transverse bends is 2 times, and the static specific capacitance is 0.803 μF / cm 2 ; the number of longitudinal bends of the anode foil obtained in Example 9 is 136 times, the number of transverse bends is 72 times, and the static specific capacitance is 0.795 μF / cm 2 .

[0284] Comparative Example 12

[0285] Step 1: Mix and stir evenly a solvent (terpineol and glycerol), a binder (ethyl cellulose and polyvinyl butyral), and additives (a polyether defoamer, a dispersant triethanolamine, and a silane coupling agent) in a mass ratio of 95:5:8:2:2:2:2 to obtain a mixed solution. Mix and stir evenly the mixed solution and a solid aluminum-containing powder (aluminum powder and a water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fraction of potassium sulfate in the solid aluminum-containing powder is 2%.

[0286] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 90 °C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 50 μm.

[0287] Step 3: Wash and dry the aluminum foil blank obtained in Step 2. The washing process is to wash the aluminum foil blank with deionized water at 70°C; the washing method is immersion; the drying temperature is 80°C.

[0288] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace, and the heat treatment process is as follows: First, heat from room temperature to 400°C in air at a heating rate of 10°C / min and hold for 4 h; then heat to 590°C in vacuum at a heating rate of 0.1°C / min and hold for 4 h, and then cool with the furnace after the holding ends.

[0289] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry. The film solution is polyvinyl alcohol; the coating method is screen printing; the film thickness is 15 μm.

[0290] Step 6: Sinter the aluminum foil with a protective film layer on the surface obtained in Step 5. The sintering is carried out in a bell furnace, and the sintering process is as follows: Heat to 630°C in argon at a heating rate of 20°C / min and hold for 10 h, and then cool with the furnace after the holding ends.

[0291] Step 7: Carry out boiling water treatment and formation treatment on the sintered foil obtained in Step 6, wash with deionized water, and dry at 100°C to obtain an anode foil. Among them, the boiling water treatment uses deionized water at 100°C and the boiling water treatment time is 15 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L and the formation voltage is 520 V.

[0292] Example 10

[0293] Step 1: Mix and stir evenly the solvent (terpineol and glycerol), binder (ethyl cellulose and polyvinyl butyral), additives (polyether defoamer, dispersant triethanolamine and silane coupling agent) in a mass ratio of 95:5:8:2:2:2:2 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder and water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fraction of potassium sulfate in the solid aluminum-containing powder is 2%.

[0294] Step 2: Coat the upper surface of the aluminum foil substrate with the slurry obtained in Step 1 using a doctor blade and dry; after turning 180°, coat the slurry on the current upper surface of the aluminum foil substrate using a doctor blade and dry to obtain an aluminum foil blank. The drying temperature is 90°C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the dried aluminum paste coated on the upper and lower surfaces is 50 μm.

[0295] Step 3: Wash and dry the aluminum foil blank obtained in Step 2. The washing process is to clean the aluminum foil blank with deionized water at 70°C; the cleaning method is soaking; the drying temperature is 80°C.

[0296] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 400°C in air at a heating rate of 10°C / min and hold for 4 h; then heat to 590°C in vacuum at a heating rate of 0.1°C / min and hold for 4 h, and after the holding ends, cool with the furnace.

[0297] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a thin film solution and dry. The thin film solution is polyvinyl alcohol; the coating method is screen printing; the film thickness is 15 μm.

[0298] Step 6: Roll the aluminum foil with a protective film layer on the surface obtained in Step 5. The rolling is skew rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on the surface 20 times with the length direction of the aluminum foil at an angle of 60° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on the surface 20 times with the length direction of the aluminum foil at an angle of 160° to the axis direction of the roll; the reduction in the rolling process is 5 μm; the roll diameter is 200 mm; the rolling mill is a two-high rolling mill.

[0299] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat to 630°C in argon at a heating rate of 20°C / min and hold for 10 h, and after the holding ends, cool with the furnace.

[0300] Step 8: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 7, wash with deionized water, and dry at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 15 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 520 V.

[0301] When the bending strength test is carried out using a chuck with a curvature radius of 3.5 mm, the number of longitudinal bending times of the anode foil obtained in Comparative Example 12 is 10 times, the number of transverse bending times is 11 times, and the static specific capacitance is 0.961 μF / cm 2 ; the number of longitudinal bending times of the anode foil obtained in Example 10 is 152 times, the number of transverse bending times is 84 times, and the static specific capacitance is 0.953 μF / cm 2 .

[0302] Comparative Example 13

[0303] Step 1: Mix the solvent (diethylene glycol butyl ether acetate and ethylene glycol), binder (ethyl cellulose and polyvinyl butyral), and additives (organosilicon defoamer and silane coupling agent) evenly by stirring at a mass ratio of 50:50:6:2:0.5:5 to obtain a mixed solution. Mix the mixed solution with solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) evenly by stirring at a mass ratio of 100:200 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are 0.3% and 0.2% respectively.

[0304] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 20 μm, and the thickness of the aluminum paste coated on both the upper and lower surfaces after drying is 55 μm.

[0305] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 60 °C; the washing method is ultrasonic cleaning; the drying temperature is 100 °C.

[0306] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 350 °C in air at a heating rate of 20 °C / min and hold for 4 h; then heat to 600 °C in argon at a heating rate of 3 °C / min and hold for 4 h, and after the holding ends, cool with the furnace.

[0307] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a thin film solution and dry it. The thin film solution is ethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the thickness of the thin film is 15 μm.

[0308] Step 6: Sinter the aluminum foil with a protective film layer obtained in Step 5. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: heat to 650 °C in vacuum at a heating rate of 10 °C / min and hold for 6 h, and after the holding ends, cool with the furnace.

[0309] Step 7: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 6, wash it with deionized water, and dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 15 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 700 V.

[0310] Example 11

[0311] Step 1: Mix the solvent (diethylene glycol butyl ether acetate and ethylene glycol), binder (ethyl cellulose and polyvinyl butyral), and additives (organosilicon defoamer and silane coupling agent) evenly by stirring at a mass ratio of 50:50:6:2:0.5:5 to obtain a mixed solution. Mix the mixed solution with solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, and modified corn starch) evenly by stirring at a mass ratio of 100:200 to obtain a slurry; the particle size of the aluminum powder is 0.5 μm to 5 μm, and the mass purity is 99.99%. The mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are 0.3% and 0.2% respectively.

[0312] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it. After turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 20 μm, and the dried thickness of the aluminum paste coated on both the upper and lower surfaces is 55 μm.

[0313] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 60 °C; the washing method is ultrasonic cleaning; the drying temperature is 100 °C.

[0314] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace. The heat treatment process is as follows: First, heat from room temperature to 350 °C in air at a heating rate of 20 °C / min and hold for 4 h; then heat to 600 °C in argon at a heating rate of 3 °C / min and hold for 4 h. After the holding ends, cool with the furnace.

[0315] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is ethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the film thickness is 15 μm.

[0316] Step 6: Roll the aluminum foil with a protective film layer on the surface obtained in Step 5. The rolling is skew rolling. The rolling process is as follows: First, roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 20° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 160° to the axis direction of the roll; the reduction in the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a three-roll rolling mill.

[0317] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace. The sintering process is as follows: Heat to 650 °C in vacuum at a heating rate of 10 °C / min and hold for 6 h. After the holding ends, cool with the furnace.

[0318] Step 8: Subject the sintered foil obtained in Step 7 to water boiling treatment and formation treatment. After washing with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 15 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 700 V.

[0319] When performing the folding strength test using a chuck with a curvature radius of 3.5 mm, the number of longitudinal folds of the anode foil obtained in Comparative Example 13 is 2 times, the number of transverse folds is 4 times, and the static specific capacitance is 0.799 μF / cm 2 ; the number of longitudinal folds of the anode foil obtained in Example 11 is 155 times, the number of transverse folds is 72 times, and the static specific capacitance is 0.798 μF / cm 2 .

[0320] Comparative Example 14

[0321] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), binder (ethyl cellulose and polyvinyl butyral), and additives (organosilicon defoamer and triethanolamine dispersant) in a mass ratio of 20:40:36:2:2:9:1:1:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, and the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 1%, 0.5%, and 0.5% respectively.

[0322] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 200°C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on both the upper surface and the lower surface after drying is 60 μm.

[0323] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 20°C; the washing method is ultrasonic cleaning; the drying temperature is 120°C.

[0324] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 300°C in air at a heating rate of 2°C / min and hold for 2 h; then heat to 600°C in vacuum at a heating rate of 5°C / min and hold for 12 h, and after the holding ends, cool with the furnace.

[0325] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is screen printing; the film thickness is 25 μm.

[0326] Step 6: Sinter the aluminum foil with a protective film layer obtained in Step 5. The sintering is carried out in a bell furnace, and the sintering process is as follows: Heat it to 620 °C at a heating rate of 1 °C / min in a vacuum, hold for 10 h, and then cool it with the furnace after the holding ends.

[0327] Step 7: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 6. After washing with deionized water, dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 10 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 200 V.

[0328] Example 12

[0329] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), binder (ethyl cellulose and polyvinyl butyral), and additives (organosilicon defoamer and triethanolamine dispersant) in a mass ratio of 20:40:36:2:2:9:1:1:3 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) in a mass ratio of 100:150 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 1%, 0.5%, and 0.5% respectively.

[0330] Step 2: Coat the upper surface of the aluminum foil substrate with the slurry obtained in Step 1 using a doctor blade and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate using a doctor blade and dry it to obtain an aluminum foil blank. The drying temperature is 200 °C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 60 μm.

[0331] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 20 °C; the washing method is ultrasonic cleaning; the drying temperature is 120 °C.

[0332] Step 4: Carry out heat treatment on the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace, and the heat treatment process is as follows: First, heat it from room temperature to 300 °C at a heating rate of 2 °C / min in the air and hold for 2 h; then heat it to 600 °C at a heating rate of 5 °C / min in a vacuum and hold for 12 h, and then cool it with the furnace after the holding ends.

[0333] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is screen printing; the film thickness is 25 μm.

[0334] Step 6: Roll the aluminum foil with a protective film layer on its surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on its surface 10 times with the length direction of the aluminum foil at an angle of 40° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on its surface 10 times with the length direction of the aluminum foil at an angle of 110° to the axis direction of the roll; the reduction in the rolling process is 15 μm; the roll diameter is 100 mm; the rolling mill is a two-high rolling mill.

[0335] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat it to 620 °C at a heating rate of 1 °C / min in a vacuum, hold for 10 h, and then cool it with the furnace after the holding ends.

[0336] Step 8: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 7, wash it with deionized water, and dry it at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C, and the water boiling time is 10 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 200 V.

[0337] When the folding strength test is carried out using a chuck with a curvature radius of 3.5 mm, the number of longitudinal folding times of the anode foil obtained in Comparative Example 14 is 8 times, the number of transverse folding times is 11 times, and the static specific capacitance is 2.969 μF / cm 2 ; the number of longitudinal folding times of the anode foil obtained in Example 12 is 136 times, the number of transverse folding times is 72 times, and the static specific capacitance is 2.967 μF / cm 2 .

[0338] Comparative Example 15

[0339] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, and glycerol), the binder polyvinyl butyral, and the additives (organosilicon defoamer and acrylate leveling agent) in a mass ratio of 20:75:5:4:1:5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder and water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:250 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fraction of potassium sulfate in the solid aluminum-containing powder is 4%.

[0340] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a doctor blade and dry it. After turning it over by 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a doctor blade and dry it to obtain an aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 30 μm, and the dried thickness of the aluminum paste coated on both the upper and lower surfaces is 55 μm.

[0341] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 30°C; the washing method is immersion; the drying temperature is 60°C.

[0342] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell furnace. The heat treatment process is as follows: First, heat from room temperature to 450°C in air at a heating rate of 5°C / min and hold for 4 h; then heat to 590°C in nitrogen at a heating rate of 0.1°C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0343] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is hydroxyethyl methylcellulose; the coating method is screen printing; the film thickness is 30 μm.

[0344] Step 6: Sinter the aluminum foil with a protective film layer on its surface obtained in Step 5. The sintering is carried out in a bell furnace. The sintering process is as follows: Heat to 610°C in argon at a heating rate of 0.1°C / min and hold for 2 h, and then cool with the furnace after the holding ends.

[0345] Step 7: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 6. After washing with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C and the water boiling time is 10 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L and the formation voltage is 700 V.

[0346] Example 13

[0347] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, and glycerol), the binder polyvinyl butyral, and the additives (organosilicon defoamer and acrylate leveling agent) in a mass ratio of 20:75:5:4:1:5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder and water-soluble pore-forming agent potassium sulfate) in a mass ratio of 100:250 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fraction of potassium sulfate in the solid aluminum-containing powder is 4%.

[0348] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a doctor blade, and then dry it. After turning it over by 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a doctor blade and dry it to obtain an aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum paste coated on both the upper and lower surfaces after drying is 55 μm.

[0349] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and then dry it. The water washing process is to wash the aluminum foil blank with deionized water at 30°C; the washing method is immersion; the drying temperature is 60°C.

[0350] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat it from room temperature to 450°C in air at a heating rate of 5°C / min and hold for 4 h; then heat it to 590°C in nitrogen at a heating rate of 0.1°C / min and hold for 12 h, and then cool it in the furnace after the holding ends.

[0351] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and then dry it. The film solution is hydroxyethyl methylcellulose; the coating method is screen printing; the film thickness is 30 μm.

[0352] Step 6: Roll the aluminum foil with a protective film layer on its surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on its surface 2 times with the length direction of the aluminum foil at an angle of 60° to the axis direction of the roll, and then roll it 2 times with the length direction of the aluminum foil at an angle of 110° to the axis direction of the roll; the reduction in the rolling process is 15 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0353] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat it to 610°C in argon at a heating rate of 0.1°C / min and hold for 2 h, and then cool it in the furnace after the holding ends.

[0354] Step 8: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 7. After washing with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 10 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 700 V.

[0355] When the folding strength test is carried out with a chuck having a curvature radius of 3.5 mm, the number of longitudinal folding times of the anode foil obtained in Comparative Example 15 is 18 times, the number of transverse folding times is 15 times, and the static specific capacitance is 0.747 μF / cm 2; The number of longitudinal bends of the anode foil obtained in Example 13 is 157 times, the number of transverse bends is 97 times, and the static specific capacitance is 0.750 μF / cm 2 .

[0356] Comparative Example 16

[0357] Step 1: Mix the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol), the binder ethyl cellulose, and the additive silicone defoamer evenly by stirring at a mass ratio of 50:10:40:6:0.5 to obtain a mixed solution. Mix the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, modified corn starch) evenly by stirring at a mass ratio of 100:200 to obtain a slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 0.25%.

[0358] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 150 °C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 60 μm each.

[0359] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 70 °C; the washing method is ultrasonic cleaning; the drying temperature is 100 °C.

[0360] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 500 °C in air at a heating rate of 0.1 °C / min and hold for 2 h; then heat to 580 °C in argon at a heating rate of 5 °C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0361] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is hydroxyethyl cellulose and hydroxyethyl methyl cellulose; the coating method is screen printing; the film thickness is 15 μm.

[0362] Step 6: Sinter the aluminum foil with a protective film layer on the surface obtained in Step 5. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: heat to 650 °C in nitrogen at a heating rate of 15 °C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0363] Step 7: Subject the sintered foil obtained in Step 6 to water boiling treatment and formation treatment. After washing with deionized water, dry it at 100°C to obtain the anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 10 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 520 V.

[0364] Example 14

[0365] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol), the binder ethyl cellulose, and the additive silicone defoamer in a mass ratio of 50:10:40:6:0.5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium chloride, modified corn starch) in a mass ratio of 100:200 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.95%, and the mass fractions of sodium chloride and modified corn starch in the solid aluminum-containing powder are both 0.25%.

[0366] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain the aluminum foil blank. The drying temperature is 150°C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is both 60 μm.

[0367] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 70°C; the washing method is ultrasonic cleaning; the drying temperature is 100°C.

[0368] Step 4: Subject the porous aluminum foil blank obtained in Step 3 to heat treatment. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: first heat from room temperature to 500°C in air at a heating rate of 0.1°C / min and hold for 2 h; then heat to 580°C in argon at a heating rate of 5°C / min and hold for 12 h, and after the holding ends, cool it with the furnace.

[0369] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is hydroxyethyl cellulose and hydroxyethyl methyl cellulose; the coating method is screen printing; the film thickness is 15 μm.

[0370] Step 6: Roll the aluminum foil with a protective film layer on the surface obtained in Step 5. The rolling is diagonal rolling, and the rolling process is as follows: first roll the aluminum foil with a protective film layer on the surface 15 times with the length direction of the aluminum foil at an angle of 20° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on the surface 15 times with the length direction of the aluminum foil at an angle of 135° to the axis direction of the roll; the reduction in the rolling process is 5 μm; the roll diameter is 500 mm; the rolling mill is a two-high rolling mill.

[0371] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: heat it to 650°C at a heating rate of 15°C / min in nitrogen, hold for 12 h, and then cool it with the furnace after the holding ends.

[0372] Step 8: Perform water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 7. After cleaning with deionized water, dry it at 100°C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100°C, and the water boiling time is 10 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 520 V.

[0373] When performing the folding strength test using a chuck with a curvature radius of 3.5 mm, the number of longitudinal folding times of the anode foil obtained in Comparative Example 16 is 1 time, the number of transverse folding times is 1 time, and the static specific capacitance is 1.189 μF / cm 2 ; the number of longitudinal folding times of the anode foil obtained in Example 14 is 157 times, the number of transverse folding times is 92 times, and the static specific capacitance is 1.188 μF / cm 2 .

[0374] Comparative Example 17

[0375] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol), binder (ethyl cellulose and polyvinyl butyral), and additives (organosilicon defoamer and acrylate leveling agent) in a mass ratio of 20:30:45:5:5:5:1:6 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) in a mass ratio of 100:80 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 1%, 0.5%, and 0.5% respectively.

[0376] Step 2: Coat the slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it over 180°, coat the slurry on the current upper surface of the aluminum foil substrate with a scraper and dry it to obtain an aluminum foil blank. The drying temperature is 200°C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 50 μm.

[0377] Step 3: Wash the aluminum foil blank obtained in Step 2 and dry it. The washing process is to wash the aluminum foil blank with deionized water at 40°C; the washing method is immersion; the drying temperature is 80°C.

[0378] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace. The heat treatment process is as follows: First, heat from room temperature to 300 °C in air at a heating rate of 1 °C / min and hold for 1 h; then heat to 570 °C in nitrogen at a heating rate of 10 °C / min and hold for 10 h. After the holding ends, cool with the furnace.

[0379] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is knife coating; the film thickness is 10 μm.

[0380] Step 6: Sinter the aluminum foil with a protective film layer on the surface obtained in Step 5. The sintering is carried out in a bell-type furnace. The sintering process is as follows: Heat to 610 °C in argon at a heating rate of 20 °C / min and hold for 12 h. After the holding ends, cool with the furnace.

[0381] Step 7: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 6. After cleaning with deionized water, dry at 100 °C to obtain an anode foil. Among them, the water boiling treatment uses deionized water at 100 °C and the water boiling time is 5 min; the chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L and the chemical conversion voltage is 200 V.

[0382] Example 15

[0383] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol), binder (ethyl cellulose and polyvinyl butyral), and additives (organosilicon defoamer and acrylate leveling agent) in a mass ratio of 20:30:45:5:5:5:1:6 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, water-soluble pore-forming agent sodium sulfate, modified potato starch, and polyethylene glycol) in a mass ratio of 100:80 to obtain a slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm and the mass purity is 99.99%, and the mass fractions of sodium sulfate, modified potato starch, and polyethylene glycol in the solid aluminum-containing powder are 1%, 0.5%, and 0.5% respectively.

[0384] Step 2: Coat the upper surface of the aluminum foil substrate with the slurry obtained in Step 1 using a knife and dry it; after turning it 180°, coat the slurry on the current upper surface of the aluminum foil substrate using a knife and dry it to obtain an aluminum foil blank. The drying temperature is 200 °C, the thickness of the aluminum foil substrate is 60 μm, and the thickness of the aluminum paste coated on the upper and lower surfaces after drying is 50 μm.

[0385] Step 3: Wash the aluminum foil blank obtained in Step 2 with water and dry it. The water washing process is to wash the aluminum foil blank with deionized water at 40 °C; the washing method is soaking; the drying temperature is 80 °C.

[0386] Step 4: Heat-treat the porous aluminum foil blank obtained in Step 3. The heat treatment is carried out in a bell-type furnace, and the heat treatment process is as follows: First, heat from room temperature to 300°C in air at a heating rate of 1°C / min and hold for 1 h; then heat to 570°C in nitrogen at a heating rate of 10°C / min and hold for 10 h, and then cool with the furnace after the holding ends.

[0387] Step 5: Coat the upper and lower surfaces of the heat-treated aluminum foil obtained in Step 4 with a film solution and dry it. The film solution is polyvinyl alcohol, hydroxyethyl cellulose, and hydroxypropyl methylcellulose; the coating method is knife coating; the film thickness is 10 μm.

[0388] Step 6: Roll the aluminum foil with a protective film layer on the surface obtained in Step 5. The rolling is skew rolling, and the rolling process is as follows: First, roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 45° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer on the surface 10 times with the length direction of the aluminum foil at an angle of 160° to the axis direction of the roll; the reduction in the rolling process is 10 μm; the roll diameter is 400 mm; the rolling mill is a two-high rolling mill.

[0389] Step 7: Sinter the rolled aluminum foil obtained in Step 6. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: Heat to 610°C in argon at a heating rate of 20°C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0390] Step 8: Carry out boiling water treatment and forming treatment on the sintered foil obtained in Step 7, wash it with deionized water, and dry it at 100°C to obtain an anode foil. Among them, the boiling water treatment uses deionized water at 100°C, and the boiling water treatment time is 5 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 200 V.

[0391] When the bending strength test is carried out using a chuck with a radius of curvature of 3.5 mm, the number of longitudinal bending times of the anode foil obtained in Comparative Example 17 is 12 times, the number of transverse bending times is 8 times, and the static specific capacitance is 2.442 μF / cm 2 ; the number of longitudinal bending times of the anode foil obtained in Example 15 is 171 times, the number of transverse bending times is 94 times, and the static specific capacitance is 2.434 μF / cm 2 .

[0392] Table 1 shows the performance test results of the anode foils prepared in Comparative Examples 1 - 17 and Examples 1 - 15.

[0393] Table 1

[0394]

[0395] As can be seen from Table 1: For the anode foil prepared in Comparative Example 1 and processed by a roller set at an inclination, the static specific capacitance is 0.926 μF / cm 2 , the number of longitudinal bending times is 118, and the number of transverse bending times is 66; for the anode foil prepared in Comparative Example 2 and processed by a roller with balls rotatable about their own centers of spheres provided on the circumferential surface thereof and set at an inclination, the static specific capacitance is 0.934 μF / cm 2 , the number of longitudinal bending times is 124, and the number of transverse bending times is 58; for the anode foil prepared in Example 1 and processed by skew rolling with a rolling mill, the static specific capacitance is 0.951 μF / cm 2 , the number of longitudinal bending times is 136, and the number of transverse bending times is 72; under the condition of the same number of processing times, the performance (static specific capacitance and bending times) of the anode foil prepared in Example 1 is higher than that of the anode foils prepared in Comparative Example 1 and Comparative Example 2.

[0396] In addition, the transverse and longitudinal anti-bending performances of the non-rolled anode foils prepared in Comparative Examples 3 to 17 are relatively poor, and the number of their bending times is within 20; for the anode foils prepared in Examples 1 to 15 and processed by skew rolling with a rolling mill, the number of transverse bending times reaches more than 50, and the number of longitudinal bending times reaches more than 100. By comparing Comparative Examples 3 to 17 and Examples 1 to 15, it can be seen that under the same test conditions, the number of bending times of the anode foils in the examples is increased by more than 300% compared with that of the anode foils in the comparative examples, greatly improving the transverse and longitudinal anti-bending performances of the anode foils and meeting the requirements of machining. In addition, the anode foils in Examples 1 to 15 also have relatively large static specific capacitances, meeting the requirements for improving the performance of subsequent capacitors. Therefore, the preparation method of the anode foil provided by the present disclosure can improve the anti-bending performance of the anode foil, and further improve the overall performance of the device.

[0397] It should be noted that although the steps of the preparation method of the aluminum electrolytic capacitor anode foil in the present disclosure are described in a specific order in the drawings, this does not require or imply that these steps must be executed in this specific order, or that all the steps shown must be executed to achieve the desired result. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step for execution, and / or one step may be decomposed into multiple steps for execution, etc.

[0398] Other embodiments of the present disclosure will be readily apparent to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and examples are only to be considered as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

Claims

1. A method for preparing an anode foil for an aluminum electrolytic capacitor, characterized in that: include: Step S1: preparing aluminum paste, wherein the aluminum paste comprises a mixed solution and solid aluminum-containing powder, wherein the mixed solution is prepared by mixing a solvent, a binder and an additive, and the solid aluminum-containing powder comprises aluminum powder and a water-soluble pore-forming agent; Step S2: providing an aluminum foil substrate, coating the aluminum paste on the surface of the aluminum foil substrate, and performing a drying process to form an aluminum foil blank; Step S3: washing the dried aluminum foil blank with water, and drying it to obtain a porous aluminum foil blank; Step S4: heat treating the porous aluminum foil blank; Step S5: coating a thin film solution on the surface of the porous aluminum foil blank after the heat treatment, and performing a drying treatment to form a protective film layer on the surface of the porous aluminum foil blank; The film solution is an aqueous solution prepared by one or more of hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, polyethylene glycol, polyvinyl alcohol, and polyvinyl pyrrolidone; Step S6: using a rolling mill to perform a rolling process on the porous aluminum foil blank having the protective film layer in a skew rolling manner to obtain an initial anode foil; The rolling process comprises: performing a first rolling process on the porous aluminum foil blank with the protective film layer, wherein the first rolling process is performed at an angle of 20° to 70° between the axis direction of the roller and the length direction of the porous aluminum foil blank; performing a second rolling process on the porous aluminum foil blank with the protective film layer, wherein the axis direction of the roller is performed at an angle of 110° to 160° between the axis direction of the roller and the length direction of the porous aluminum foil blank; and the diameter of the roller is 65 mm to 600 mm; Step S7: sintering the initial anode foil to remove the protective film layer to form a sintered foil.

2. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: The rolling mill is one of a two-roll rolling mill, a three-roll rolling mill or a four-roll rolling mill, and the rolling mill has a roller pressure of 5 μm to 15 μm. In step S6, the porous aluminum foil blank having the protective film layer is rolled by the rolling mill in a skew rolling manner to obtain an initial anode foil. The method includes: The first rolling treatment of the porous aluminum foil blank having the protective film layer is repeated rolling of the porous aluminum foil blank 2 to 20 times; The porous aluminum foil blank having the protective film layer is subjected to a second rolling process, which is to repeatedly roll the porous aluminum foil blank 2 to 20 times.

3. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: In step S5, a thin film solution is coated on the surface of the thermally treated porous aluminum foil blank, and the method comprises: The porous aluminum foil blank is coated with the thin film solution on both sides by using a blade coating or screen printing method; the thickness of the protective film layer on each side of the porous aluminum foil blank is the same, and the thickness of the protective film layer on each side of the porous aluminum foil blank is 5μm~30μm.

4. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: The mass fraction of the water-soluble pore-forming agent to the solid aluminum-containing powder is 0.5% to 4%; the mass ratio of the mixed solution to the solid aluminum-containing powder is 100:(80 to 250); The water-soluble pore-forming agent is one or more of a water-soluble neutral salt, a water-soluble starch, and a water-soluble resin; The water-soluble neutral salt is one or more of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate; The water-soluble starch is one or more of modified corn starch, modified potato starch, modified sweet potato starch, modified cassava starch, modified wheat starch, and modified mung bean starch; The water-soluble resin is one or more of polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose.

5. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: In step S3, the dried aluminum foil blank is washed with water and dried to obtain a porous aluminum foil blank, comprising: The aluminum foil blank is cleaned with deionized water at 10° C. to 80° C. by immersion or ultrasonic cleaning. The cleaned aluminum foil blank is dried at a drying temperature of 40° C. to 120° C.

6. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: In step S4, the porous aluminum foil blank is subjected to heat treatment, including: In an air atmosphere, heating the porous aluminum foil blank from room temperature to 300° C. to 500° C. at a heating rate of 0.1° C. / min to 20° C. / min, and keeping the temperature for 1 h to 8 h; In a nitrogen, argon or vacuum atmosphere, the porous aluminum foil blank is continuously heated to 570° C. to 600° C. at a heating rate of 0.1° C. / min to 20° C. / min, and kept at this temperature for 4 h to 12 h; After the insulation is completed, cool down with the furnace.

7. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: The mass ratio of the solvent, the binder and the additive in the mixed solution is 100:(3-10):(0.5-10); The solvent is a mixture of a first solvent and a second solvent, the first solvent is one or both of terpineol and diethylene glycol butyl ether acetate, and the second solvent is one or more of ethylene glycol, propylene glycol, and glycerol; The binder is one or two of ethyl cellulose and polyvinyl butyral; The additives include one or more of a defoamer, a leveling agent, a dispersant, and a coupling agent. The defoamer is a silicone defoamer or a polyether defoamer, the leveling agent is an acrylic leveling agent, the dispersant is triethanolamine, and the coupling agent is a silane coupling agent.

8. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: The thickness of the aluminum foil substrate is 20 μm to 60 μm, and the aluminum foil substrate has an upper surface and a lower surface that are arranged opposite to each other. In step S2, the aluminum foil blank is formed. The method includes: The aluminum foil substrate is double-sided coated with the aluminum paste to form aluminum paste film layers with the same thickness on the upper surface and the lower surface of the aluminum foil substrate; The aluminum foil substrate with the aluminum paste film layer is dried at a drying temperature of 90° C. to 200° C., and the thickness of the aluminum paste film layer after drying is 50 μm to 60 μm.

9. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: In step S7, the sintering process includes: In a nitrogen, argon or vacuum atmosphere, heating the initial anode foil from room temperature to 610° C. to 650° C. at a heating rate of 0.1° C. / min to 20° C. / min, and keeping the temperature for 4 h to 12 h; After the insulation is completed, cool down with the furnace.

10. The method for preparing an anode foil for an aluminum electrolytic capacitor according to claim 1, characterized in that: After step S7, the method further comprises: The sintered foil is subjected to a water boiling treatment to form an intermediate anode foil, wherein the water boiling treatment comprises boiling the sintered foil in deionized water at 100° C. for 5 to 15 minutes; Performing a chemical formation treatment on the intermediate anode foil to form an oxide layer on the intermediate anode foil to obtain a target anode foil, wherein the chemical formation treatment has a chemical formation voltage of 200V to 700V; The target anode foil is cleaned and dried.

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