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

Abstract

The present disclosure provides a method for preparing an anode foil and an aluminum electrolytic capacitor, relating to the technical field of capacitors. The preparation method includes: preparing an aluminum-containing slurry, the aluminum-containing slurry including a mixed solution and a solid aluminum-containing powder, the mixed solution being prepared by mixing a solvent, a binder, and an additive, and the solid aluminum-containing powder including aluminum powder and ceramic powder; providing an aluminum foil substrate, coating the aluminum-containing slurry on the surface of the aluminum foil substrate, and performing a drying treatment to form an aluminum foil blank; coating a thin film solution on the surface of the aluminum foil blank, and performing a drying treatment to form a protective film layer on the surface of the aluminum foil blank; using a rolling mill to perform a rolling treatment on the aluminum foil blank having the protective film layer in an inclined rolling manner to obtain an initial anode foil; and 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 and an aluminum electrolytic capacitor. Background Art

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

[0003] Currently, the method of generating irregular multi-directional cracks on the surface of an aluminum foil by using a roller inclinedly arranged in a conveying trough or a roller with balls rotatable around its own spherical center on the circumferential surface can be adopted to improve the bending resistance of the anode foil in the transverse and longitudinal directions. However, this treatment method is prone to problems such as scratching and powder falling on the surface of the foil and wrinkling of the foil, which will lead to adhesion of the foil during the coiling and sintering of the aluminum foil, and an anode foil with a flat surface and good bending resistance cannot be produced.

[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 and an aluminum electrolytic capacitor are 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 surface of the anode foil.

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

[0007] According to one aspect of the present disclosure, a method for preparing an anode foil is provided, and this preparation method includes:

[0008] Step S1: Prepare an aluminum-containing slurry, the aluminum-containing slurry includes a mixed solution and 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 ceramic powder;

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

[0010] Step S3: Coat a film solution on the surface of the aluminum foil blank and perform a drying process to form a protective film layer on the surface of the aluminum foil blank;

[0011] Step S4: Use a rolling mill to roll the aluminum foil blank with the protective film layer in a skew rolling manner to obtain an initial anode foil;

[0012] Step S5: Sinter the initial anode foil to remove the protective film layer to form a sintered foil.

[0013] 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 S4, use a rolling mill to roll the aluminum foil blank with the protective film layer in a skew rolling manner to obtain an initial anode foil. The method includes:

[0014] Perform a first rolling process on the aluminum foil blank with the protective film layer. The first rolling process is to repeatedly roll the aluminum foil blank 2 to 20 times when the axial direction of the rolling mill rolls forms an angle of 20° to 70° with the length direction of the aluminum foil blank;

[0015] Then perform a second rolling process on the aluminum foil blank with the protective film layer. The second rolling process is to repeatedly roll the aluminum foil blank 2 to 20 times when the axial direction of the rolling mill rolls forms an angle of 110° to 160° with the length direction of the aluminum foil blank.

[0016] In an exemplary embodiment of the present disclosure, the 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 S3, coat the film solution on the surface of the aluminum foil blank. The method includes:

[0017] Use one of knife coating or screen printing to double-side coat the film solution on the aluminum foil blank; the thickness of the protective film layer on each side of the aluminum foil blank is the same, and the thickness of the protective film layer on each side of the aluminum foil blank is 5 μm to 30 μm.

[0018] In an exemplary embodiment of the present disclosure, the mass fraction of the ceramic powder in the solid aluminum-containing powder is 1% to 10%; the mass ratio of the mixed solution to the solid aluminum-containing powder is 100:(80 - 250).

[0019] In an exemplary embodiment of the present disclosure, the ceramic powder is one or more of alumina, titanium dioxide, barium titanate, and strontium titanate; the particle size of the ceramic powder is 0.5 μm to 10 μm.

[0020] In an exemplary embodiment of the present disclosure, the mass ratio of the solvent, binder, and additive in the mixed solution is 100:(3 to 10):(0.5 to 10);

[0021] 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;

[0022] The binder is one or two of ethyl cellulose and polyvinyl butyral;

[0023] The additive includes one or more of an antifoaming agent, a leveling agent, a dispersant, and a coupling agent. The antifoaming agent is a silicone 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.

[0024] In an exemplary embodiment of the present disclosure, the thickness of the aluminum foil substrate is 20 μm to 60 μm. The aluminum foil substrate has an upper surface and a lower surface that are oppositely arranged. In step S2, forming the aluminum foil blank, the method includes:

[0025] Using the aluminum-containing slurry, double-sidedly coat 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;

[0026] Under the condition that the drying temperature is 90 °C to 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 to 60 μm.

[0027] In an exemplary embodiment of the present disclosure, in step S5, the sintering treatment includes:

[0028] In an air atmosphere, heat the initial anode foil from room temperature to 300 °C to 500 °C at a heating rate of 0.1 °C / min to 20 °C / min, and keep it warm for 1 h to 8 h;

[0029] In a nitrogen, argon, or vacuum atmosphere, continue to heat the initial anode foil to 610 °C to 650 °C at a heating rate of 0.1 °C / min to 20 °C / min, and keep it warm for 4 h to 12 h;

[0030] After the heat preservation is completed, cool it with the furnace.

[0031] In an exemplary embodiment of the present disclosure, after step S5, the method further includes:

[0032] Performing a water boiling treatment on the sintered foil to form an intermediate anode foil, where the water boiling treatment includes boiling the sintered foil in deionized water at 100 °C for 5 min to 15 min;

[0033] 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, where the forming voltage of the forming treatment is 200 V to 700 V.

[0034] According to another aspect of the present disclosure, an aluminum electrolytic capacitor is provided, and the aluminum electrolytic capacitor includes an anode foil made by the above preparation method.

[0035] The preparation method of the anode foil provided by the present disclosure includes adding ceramic powder to an aluminum-containing slurry. The aluminum-containing slurry is coated on the surface of an aluminum foil substrate and dried to obtain an aluminum foil blank. Then, a protective film layer is coated on the surface of the aluminum foil blank, and the aluminum foil blank is rolled by a rolling mill in a skew rolling manner and sintered to obtain a sintered foil. The surface of the sintered foil obtained by this preparation method has 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 aluminum foil blank first and then performing skew rolling by 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 aluminum foil blanks, and during the subsequent sintering process, the adhesion between aluminum foil blanks can be avoided. In addition, the rolling roll 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 wrinkles caused by roll bending, improve the production quality of the anode foil, and an anode foil with a flat surface and good anti-bending performance can be produced by this preparation method.

[0036] The aluminum electrolytic capacitor provided by the present disclosure includes an anode foil prepared by the above method, and the capacitor has good mechanical properties and good overall device performance.

[0037] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings herein are incorporated into the specification and form a part of the 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.

[0039] Figure 1 It is a flowchart of a method for preparing an anode foil in an exemplary embodiment of the present disclosure.

[0040] Figure 2 It is a light microscope image of the anode foil prepared in Comparative Example 1.

[0041] Figure 3 It is a light microscope image of the anode foil prepared in Comparative Example 2.

[0042] Figure 4 It is a light microscope image of the anode foil prepared in Example 1 provided by the present disclosure. Detailed implementation manners

[0043] 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 the same or similar structures, and thus their detailed descriptions will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0044] 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 mean an open inclusion 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 only used as labels and are not a limitation on the quantity of their objects.

[0045] In the related art, in order to improve the anti-bending performance of the electrode 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 the conveying roller and the roller. The conveying roller is used to convey the foil forward. The foil bypasses the roller obliquely. 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 groups of rollers can process multiple cracks simultaneously; alternatively, a number of balls (with a diameter of 2 mm to 4 mm) that can rotate around their own spherical centers can be provided on the circumferential surface of the roller (with a diameter of 8 mm to 12 mm). The balls are in contact with the electrode foil. By making the foil surface of the electrode foil roll relative to the balls that can rotate in multiple directions around their own spherical centers and under the interaction of the winding tension, cracks in multiple directions are formed on the foil surface of the electrode foil.

[0046] However, when preparing the electrode foils by the above two methods, scratches and powder falling are likely to occur on the surfaces of the electrode foils, and the flatness and integrity of the surfaces of the electrode foils cannot be guaranteed, resulting in easy adhesion of the foil sheets during the coiling and sintering of the aluminum foils. In addition, the existing technology uses small-diameter rollers (20 mm or less), and the stiffness of the small rollers is poor, which is prone to bending when continuously processing the foils, easily causing the foils to wrinkle, and resulting in the inability to produce an anode foil with a flat surface and good anti-bending performance.

[0047] Based on this, the embodiments of the present disclosure provide a method for preparing an anode foil, as Figure 1 shown, the preparation method includes: step S1 to step S5.

[0048] Among them, step S1: Prepare an aluminum-containing slurry, the aluminum-containing slurry 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 ceramic powder;

[0049] Step S2: Provide an aluminum foil substrate, coat the aluminum-containing slurry on the surface of the aluminum foil substrate, and perform a drying treatment to form an aluminum foil blank;

[0050] Step S3: Coat a thin film solution on the surface of the aluminum foil blank, and perform a drying treatment to form a protective film layer on the surface of the aluminum foil blank;

[0051] Step S4: Use a rolling mill to roll the aluminum foil blank with a protective film layer in a skew rolling manner to obtain an initial anode foil;

[0052] Step S5: Perform a sintering treatment on the initial anode foil to remove the protective film layer to form a sintered foil.

[0053] The method for preparing an anode foil provided by the present disclosure adds ceramic powder to the aluminum-containing slurry. The aluminum-containing slurry is coated on the surface of the aluminum foil substrate and dried to obtain an aluminum foil blank. Then, a protective film layer is coated on the surface of the aluminum foil blank, and the aluminum foil blank is rolled by a rolling mill in a skew rolling manner and sintered to obtain a sintered foil. The surface and interior of the sintered foil obtained by this preparation 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 first coating a protective film layer on the surface of the aluminum foil blank and then performing skew rolling by a rolling mill, the problems of surface scratches, powder falling and wrinkling of the anode foil can be solved. The protective film layer can form a gap between adjacent aluminum foil blanks, and during the subsequent sintering process, the adhesion between the aluminum foil blanks can be avoided, improving the production quality of the anode foil. By this preparation method, an anode foil with a flat surface and good anti-bending performance can be produced.

[0054] The following will specifically describe each step of the method for preparing an anode foil provided by the embodiments of the present disclosure:

[0055] In the embodiments provided by the present disclosure, in step S1, an aluminum-containing paste is prepared. The aluminum-containing 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 ceramic powder.

[0056] Among them, the aluminum-containing paste 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.

[0057] 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 paste, the aluminum-containing paste can have the characteristics of low evaporation rate, easy storage, and moderate viscosity at room temperature. The solvent is easy to evaporate during the drying process, and the aluminum-containing paste has good leveling property. There is no residue or little residue of the binder and the additive during the heat treatment process.

[0058] Among them, the aluminum-containing paste 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.

[0059] 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, or 5 μm, etc. During the preparation of the aluminum powder, there can be aluminum powders with various 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.

[0060] The solid aluminum-containing powder includes ceramic powder. The mass fraction of the ceramic powder in the solid aluminum-containing powder is 1% to 10%. For example, the mass fraction of the ceramic powder in the solid aluminum-containing powder can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc. The ceramic powder can be one or more of alumina, titanium dioxide, barium titanate, and strontium titanate. The particle size of the ceramic powder can be 0.5 μm to 10 μm. For example, its particle size can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, etc. During the preparation of the aluminum powder, there can be ceramic powders with various different particle sizes in the solid aluminum-containing powder. In some exemplary embodiments, the particle sizes of the ceramic powders in the solid aluminum-containing powder can be the same or approximately the same. By adding ceramic powder to the solid aluminum-containing powder, the internal stress during the subsequent sintering process can be increased, so that irregular multi-directional cracks are formed inside the sintered foil. It can also improve the high-temperature resistance and chemical stability of the anode foil formed subsequently, and improve the service life of the anode foil.

[0061] In the embodiment provided by the present disclosure, in step S2, an aluminum foil substrate is provided, and an aluminum-containing slurry is coated on the surface of the aluminum foil substrate and dried to form an aluminum foil blank.

[0062] 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 different 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, an example is given where the thickness of the aluminum foil substrate is the average distance between the upper surface and the lower surface.

[0063] In some embodiments, in step S2, forming an aluminum foil blank includes: using an aluminum-containing slurry to coat both sides of an aluminum foil substrate to form aluminum slurry film layers of 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.

[0064] Among them, the double-sided coating of the aluminum foil substrate can adopt coating methods such as doctor blade coating and screen printing to form aluminum slurry film layers of 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 50μm to 60μm. For example, it can be 50μm, 52μm, 54μm, 56μm, 58μm or 60μm, etc. By controlling the thickness 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.

[0065] 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 1μm, it can be considered that their thicknesses are the same.

[0066] 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. 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 make the slurry have good leveling property and the solvent volatilize more thoroughly by controlling the drying temperature.

[0067] In the embodiments provided by the present disclosure, in step S3, a thin film solution is coated on the surface of the aluminum foil blank and dried to form a protective film layer on the surface of the aluminum foil blank.

[0068] 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.

[0069] A thin film solution is coated on the surface of the aluminum foil blank. The method includes: performing double-sided coating of the thin film solution on the aluminum foil blank in one of the forms of knife coating or screen printing; the thickness of the protective film layer is the same on each side of the aluminum foil blank. The thickness of the protective film layer on each side of the 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 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, the protective film layer is not easily detached during the subsequent rolling process, so as to protect the aluminum paste film layer from being scratched and losing powder, and the protective film layer is relatively easy to remove during the subsequent sintering process and will not have an adverse impact on the overall structure of the anode foil.

[0070] In the embodiment provided by the present disclosure, in step S4, a rolling mill is used to perform rolling treatment on the aluminum foil blank with a protective film layer in a skew rolling manner to obtain an initial anode foil.

[0071] The rolling mill can be one of a two-high rolling mill, a three-high rolling mill, or a four-high rolling mill. In order to improve the rolling quality of the rolling mill for the aluminum foil blank, the rolling reduction of the rolling mill can be 5 μm to 15 μm. For example, the rolling 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. In order to avoid phenomena such as powder loss or scratching of the aluminum foil blank during the rolling process, 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.

[0072] In some embodiments, a rolling mill is used to perform rolling treatment on the aluminum foil blank with a protective film layer in a skew rolling manner to obtain an initial anode foil. The method includes:

[0073] Performing a first rolling treatment on the aluminum foil blank with a protective film layer. The first rolling treatment is to repeat rolling the 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 performing a second rolling treatment on the aluminum foil blank with a protective film layer. The second rolling treatment is to repeat rolling the 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.

[0074] Among them, in the first rolling process, the axial direction of the rolling mill rolls can be at an angle of 20° to 70° with the length direction of the 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 is at an angle of 110° to 160° with the length direction of the 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.

[0075] 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 aluminum foil blank is not easily detached 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 around the ceramic powder in 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.

[0076] In the embodiment provided by the present disclosure, in step S5, the initial anode foil is sintered to remove the protective film layer to form a sintered foil.

[0077] Among them, sintering the initial anode foil includes: in an air atmosphere, heating the initial anode foil 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 initial anode foil to 610°C to 650°C at a heating rate of 0.1°C / min to 20°C / min and holding for 4 h to 12 h; after holding, cooling with the furnace.

[0078] For the first treatment of the initial anode foil in the above embodiment, the parameters of the first treatment are: in an air atmosphere, the first heating rate is 0.1°C / min to 20°C / min. For example, the first heating rate can be 0.1°C / min, 5°C / min, 10°C / min, 15°C / min or 20°C / min, etc.; heating the initial anode foil from room temperature to the first temperature, the room temperature is 20 to 25°C, and the first temperature is 300°C to 500°C. For example, the first temperature can be 300°C, 350°C, 400°C, 450°C or 500°C, etc.; the first holding time is 1 h to 8 h. For example, the first holding time can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h or 8 h, etc.

[0079] After the first treatment, the initial anode foil continues to be subjected to a second treatment. The parameters of the second treatment are as follows: in a nitrogen, argon or vacuum atmosphere, the second heating rate is 0.1 °C / min to 20 °C / min. For example, the second 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 after the first treatment is heated from the first temperature to the second temperature, and the second temperature is 610 °C to 650 °C. For example, the second temperature can be 610 °C, 620 °C, 630 °C, 640 °C or 650 °C, etc.; the second holding time is 4 h to 12 h. For example, the second holding time can be 4 h, 6 h, 8 h, 10 h or 12 h, etc.

[0080] By adjusting and controlling parameters such as the heating rate, sintering atmosphere, holding temperature and holding time of the sintering treatment, the protective film layer on the surface of the sintered foil can be removed completely, and at the same time, the surface of the sintered foil is 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.

[0081] In the embodiment provided by the present disclosure, after step S5, 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, thereby obtaining the target anode foil.

[0082] 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.

[0083] 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 sintered foil, which is beneficial to the formation of an oxide layer in the subsequent forming treatment.

[0084] 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.

[0085] By adjusting and controlling the formation voltage, anode foils with various rated withstand voltage requirements can be produced.

[0086] The disclosed embodiment also provides an aluminum electrolytic capacitor, which includes an anode foil prepared by the above method. The capacitor has good mechanical properties and good overall device performance.

[0087] The following is a further description of the method for preparing the anode foil provided by the present disclosure through specific examples:

[0088] Comparative Example 1

[0089] Step 1: Mix and stir the solvent (pinene alcohol, 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 the mixed solution with solid aluminum-containing powder (aluminum powder, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; wherein the particle size of the aluminum powder is 0.5μm~5μm, the mass purity is 99.99%, the particle size of the alumina ceramic powder is 0.5μm~10μm, and the mass fraction of the alumina ceramic powder in the solid aluminum-containing powder is 5%.

[0090] Step 2: Apply the aluminum-containing slurry obtained in step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it; after turning it 180°, apply the aluminum-containing 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 30μm, and the thickness of the aluminum-containing slurry applied on the upper and lower surfaces after drying is 50μm.

[0091] Step 3: The aluminum foil blank obtained in step 2 is passed through a roller with a diameter of 12 mm to produce cracks on the foil surface. The process is: first, the aluminum foil blank is passed through the roller at an angle of 40° between the length direction and the axis direction of the roller, and this is repeated 10 times; then, the aluminum foil blank is passed through the roller at an angle of 140° between the length direction and the axis direction of the roller, and this is repeated 10 times.

[0092] Step 4: Sinter the aluminum foil blank obtained in step 3. The sintering is carried out in a bell-type furnace, and the sintering process is: firstly, heating from room temperature to 500°C in air at a heating rate of 0.1°C / min, and keeping the temperature for 1 hour; then, heating to 650°C in nitrogen at a heating rate of 0.1°C / min, and keeping the temperature for 4 hours, and then cooling with the furnace after the end of the heat preservation.

[0093] Step 5: Subject the sintered foil obtained in Step 4 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 at 100 g / L, and the formation voltage is 520 V.

[0094] Control Example 2

[0095] 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 (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 the solid aluminum-containing powder (aluminum powder, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina ceramic powder is 0.5 μm to 10 μm, and the mass fraction of the alumina ceramic powder in the solid aluminum-containing powder is 5%.

[0096] Step 2: Coat the upper surface of the aluminum foil substrate with the aluminum-containing slurry obtained in Step 1 using a scraper and dry it; after turning it 180°, coat the aluminum-containing slurry on the current upper surface of the aluminum foil substrate using 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-containing slurry coated on both the upper and lower surfaces after drying is 50 μm.

[0097] Step 3: Process cracks on the surface of the foil of the aluminum foil blank obtained in Step 2 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 blank through the roller with the length direction of the aluminum foil blank at an angle of 40° to the axis direction of the roller, and repeat passing 10 times. Then, pass the aluminum foil blank through the roller with the length direction of the aluminum foil blank at an angle of 140° to the axis direction of the roller, and repeat passing 10 times.

[0098] Step 4: Sinter the aluminum foil blank obtained in Step 3. The sintering is carried out in a bell-type furnace. The sintering 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 650°C in nitrogen at a heating rate of 0.1°C / min and hold for 4 h. After the holding ends, cool with the furnace.

[0099] Step 5: Subject the sintered foil obtained in Step 4 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.

[0100] Control Example 3

[0101] 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 (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 the solid aluminum-containing powder (aluminum powder, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina ceramic powder is 0.5 μm to 10 μm, and the mass fraction of the alumina ceramic powder in the solid aluminum-containing powder is 5%.

[0102] Step 2: Coat the upper surface of the aluminum foil substrate with the aluminum-containing slurry obtained in Step 1 using a doctor blade, and dry it. After turning it over 180°, coat the current upper surface of the aluminum foil substrate with the aluminum-containing slurry using a doctor blade 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 dried aluminum-containing slurry coated on the upper and lower surfaces is 50 μm.

[0103] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is doctor blade coating; the thickness of the protective film layer is 30 μm.

[0104] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: First, heat from room temperature to 500°C at a heating rate of 0.1°C / min in air and hold for 1 h; then heat to 650°C at a heating rate of 0.1°C / min in nitrogen and hold for 4 h. After the holding ends, cool with the furnace.

[0105] Step 5: Subject the sintered foil obtained in Step 4 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.

[0106] Example 1

[0107] Step 1: Mix 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) evenly by stirring at a mass ratio of 40:30:10:10:10:5:5:1:1:5:3 to obtain a mixed solution. Mix the mixed solution with solid aluminum-containing powder (aluminum powder, alumina ceramic powder) evenly by stirring at a mass ratio of 100:80 to obtain an aluminum-containing slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina ceramic powder is 0.5 μm to 10 μm, and the mass fraction of the alumina ceramic powder in the solid aluminum-containing powder is 5%.

[0108] Step 2: Coat the aluminum-containing 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 aluminum-containing 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-containing slurry coated on both the upper surface and the lower surface after drying is 50 μm.

[0109] Step 3: Coat the upper surface and the lower surface of the aluminum foil blank obtained in Step 2 with a film solution and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is scraper coating; the thickness of the protective film layer is 30 μm.

[0110] Step 4: Roll the aluminum foil blank with a protective film layer obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: first roll the aluminum foil blank with a protective film layer 10 times with the length direction of the aluminum foil blank at an angle of 40° to the axis direction of the roll, and then roll the aluminum foil with a protective film layer 10 times with the length direction of the aluminum foil at an angle of 140° to the axis direction of the roll; the reduction of the roll in the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a four-high rolling mill.

[0111] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: first heat from room temperature to 500 °C at a heating rate of 0.1 °C / min in air and hold for 1 h; then heat to 650 °C at a heating rate of 0.1 °C / min in nitrogen and hold for 4 h, and then cool with the furnace after the holding ends.

[0112] Step 6: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 5, 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 formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 520 V.

[0113] 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 1 was 152 times, and the number of transverse bends was 76 times; the number of longitudinal bends of the anode foil obtained in Comparative Example 2 was 174 times, and the number of transverse bends was 82 times; the number of longitudinal bends of the anode foil obtained in Comparative Example 3 was 3 times, and the number of transverse bends was 2 times; the number of longitudinal bends of the anode foil obtained in Example 1 was 185 times, and the number of transverse bends was 92 times.

[0114] Compared with Comparative Examples 1 - 3, the number of bends of the anode foil obtained in Example 1 was the highest. Additionally, Figure 2 Figure 5 is a light microscope image of the anode foil obtained by using the preparation method provided in Comparative Example 1. Figure 3 Figure 6 is a light microscope image of the anode foil obtained by using the preparation method provided in Comparative Example 2. Figure 4 Figure 7 is a light microscope image of the anode foil obtained by using the preparation method provided in 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 had irregular multi-directional cracks, but there were defects such as scratches and powder shedding on the surface of the anode foils; from Figure 4 it can be seen that the surface of the anode foil obtained in Example 1 had irregular multi-directional cracks, and the surface quality of the anode foil was good, without defects such as scratches and powder shedding; the preparation method of Example 1 can obtain an anode foil with a flat surface and good anti-bending performance.

[0115] Comparative Example 4

[0116] Step 1: Mix and stir evenly a solvent (terpineol and ethylene glycol), a binder (ethyl cellulose), and an additive (organic silicon defoamer) in a mass ratio of 50:50:3:0.5 to obtain a mixed solution. Mix and stir evenly the mixed solution and a solid aluminum-containing powder (aluminum powder, alumina ceramic powder, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; wherein the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina and titanium dioxide are both 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 3% and 7% respectively.

[0117] Step 2: Coat the upper surface of the aluminum foil substrate with the aluminum-containing slurry obtained in Step 1 using a scraper and dry it; after turning it 180°, coat the current upper surface of the aluminum foil substrate with the aluminum-containing slurry using 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-containing slurry coated on the upper and lower surfaces is both 50 μm.

[0118] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is screen printing; the thickness of the protective film layer is 15 μm.

[0119] Step 4: Sinter the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: First, heat from room temperature to 400 °C at a heating rate of 10 °C / min in air and hold for 4 h; then heat to 630 °C at a heating rate of 10 °C / min in vacuum and hold for 8 h, and cool with the furnace after the holding ends.

[0120] Step 5: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 4, 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 chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 520 V.

[0121] Example 2

[0122] Step 1: Mix and stir evenly a solvent (terpineol and ethylene glycol), a binder (ethyl cellulose), and an additive (organic silicon defoamer) in a mass ratio of 50:50:3:0.5 to obtain a mixed solution. Mix and stir evenly the mixed solution and a solid aluminum-containing powder (aluminum powder, alumina powder of ceramic, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina and titanium dioxide are both 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 3% and 7% respectively.

[0123] Step 2: Coat the upper surface of the aluminum foil substrate with the aluminum-containing slurry obtained in Step 1 using a doctor blade and dry it; after turning it over 180°, coat the aluminum-containing 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 150 °C, the thickness of the aluminum foil substrate is 30 μm, and the thickness of the aluminum-containing slurry coated on the upper and lower surfaces after drying is 50 μm.

[0124] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is screen printing; the thickness of the protective film layer is 15 μm.

[0125] Step 4: Roll the aluminum foil blank with a protective film layer obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer 20 times with the length direction of the aluminum foil blank at an angle of 30° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer 20 times with the length direction of the aluminum foil blank at an angle of 150° to the axis direction of the roll; the roll reduction amount during the rolling process is 5 μm; the roll diameter is 300 mm; the rolling mill is a two-high rolling mill.

[0126] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 630 °C in vacuum at a heating rate of 10 °C / min and hold for 8 h, and after the holding is completed, cool with the furnace.

[0127] Step 6: Perform water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5. 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 520 V.

[0128] 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 4 is 1 time, and the number of transverse folding times is 1 time; the number of longitudinal folding times of the anode foil obtained in Example 2 is 169 times, and the number of transverse folding times is 98 times.

[0129] Comparative Example 5

[0130] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, and glycerol), binder (polyvinyl butyral), and 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina, titanium dioxide, and barium titanate are all 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 0.3%, 0.5%, and 0.2% respectively.

[0131] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 50 μm.

[0132] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methylcellulose, and polyvinyl alcohol; the coating method is screen printing; the thickness of the protective film layer is 5 μm.

[0133] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering 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 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.

[0134] Step 5: Perform boiling water treatment and forming treatment on the sintered foil obtained in Step 4, 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 time is 5 min; the forming treatment uses a boric acid solution of 100 g / L and the forming voltage is 520 V.

[0135] Example 3

[0136] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, and glycerol), (polyvinyl butyral), 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:150 to obtain an aluminum-containing 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 particle sizes of alumina, titanium dioxide, and barium titanate are all 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 0.3%, 0.5%, and 0.2% respectively.

[0137] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 50 μm.

[0138] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and polyvinyl alcohol; the coating method is screen printing; the thickness of the protective film layer is 5 μm.

[0139] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 2 times with the length direction of the aluminum foil blank at an angle of 60° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 2 times with the length direction of the aluminum foil blank at an angle of 120° to the axis direction of the roll; the roll reduction amount during the rolling process is 15 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0140] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: First, heat from room temperature to 300 °C at a heating rate of 20 °C / min in air and hold for 8 h; then heat to 610 °C at a heating rate of 20 °C / min in argon and hold for 12 h, and after the holding ends, cool with the furnace.

[0141] Step 6: Perform water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 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.

[0142] 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 5 is 2 times, and the number of transverse folding times is 4 times; the number of longitudinal folding times of the anode foil obtained in Example 3 is 118 times, and the number of transverse folding times is 61 times.

[0143] Comparative Example 6

[0144] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol, glycerol), binder (ethyl cellulose and polyvinyl butyral), 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, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 10%.

[0145] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper, and then dry it. After turning it over by 180°, coat the aluminum-containing 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-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0146] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is scraper coating; the thickness of the protective film layer is 20 μm.

[0147] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering 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 650°C at a heating rate of 1°C / min in nitrogen and hold for 4 h, and then cool with the furnace after the holding ends.

[0148] Step 5: Perform water boiling treatment and formation treatment on the sintered foil obtained in Step 4, 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 200 V.

[0149] Example 4

[0150] 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, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 10%.

[0151] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper, 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 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-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0152] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is knife coating; the thickness of the protective film layer is 20 μm.

[0153] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at an angle of 40° to the axis direction of the roll, and then roll it 10 times with the length direction of the aluminum foil blank at an angle of 160° to the axis direction of the roll; the reduction of the roll pressure during the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a four-high rolling mill.

[0154] Step 5: Sinter the rolled aluminum foil obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 650 °C at a heating rate of 1 °C / min in nitrogen and hold for 4 h, and then cool with the furnace after the holding ends.

[0155] Step 6: Perform boiling water treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 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 200 V.

[0156] 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 6 is 1 time, and the number of transverse folding times is 2 times; the number of longitudinal folding times of the anode foil obtained in Example 4 is 166 times, and the number of transverse folding times is 65 times.

[0157] Comparative Example 7

[0158] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, and ethylene glycol), binder (polyvinyl butyral), additives (organic silicon defoamer and 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 the solid aluminum-containing powder (aluminum powder, ceramic powder alumina, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina and titanium dioxide are both 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 4% and 1% respectively.

[0159] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it. After flipping it 180°, coat the aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0160] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is scraper coating; the thickness of the protective film layer is 15 μm.

[0161] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering 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 640°C in vacuum at a heating rate of 10°C / min and hold for 12 h, and cool with the furnace after the holding ends.

[0162] Step 5: Perform boiling water treatment and formation treatment on the sintered foil obtained in Step 4. 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 time is 10 min; the formation treatment uses a boric acid solution of 100 g / L and the formation voltage is 200 V.

[0163] Example 5

[0164] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, and ethylene glycol), binder (polyvinyl butyral), additives (organosilicon defoamer and 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 the solid aluminum-containing powder (aluminum powder, ceramic powder alumina, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina and titanium dioxide are both 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 4% and 1% respectively.

[0165] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper and dry it. After flipping it 180°, coat the aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0166] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is knife coating; the thickness of the protective film layer is 15 μm.

[0167] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 20 times with the length direction of the aluminum foil blank at an angle of 20° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 20 times with the length direction of the aluminum foil blank at an angle of 140° to the axis direction of the roll; the reduction of the roll in the rolling process is 15 μm; the roll diameter is 300 mm; the rolling mill is a three-roll rolling mill.

[0168] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: First, heat from room temperature to 350 °C at a heating rate of 5 °C / min in air and hold for 6 h; then heat to 640 °C at a heating rate of 10 °C / min in vacuum and hold for 12 h, and then cool with the furnace after the holding ends.

[0169] Step 6: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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.

[0170] When carrying out the folding strength test 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 7 is 2 times, and the number of transverse folding times is 2 times; the number of longitudinal folding times of the anode foil obtained in Example 5 is 175 times, and the number of transverse folding times is 75 times.

[0171] Comparative Example 8

[0172] 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina, titanium dioxide, and barium titanate are all 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 0.6%, 0.2%, and 0.2% respectively.

[0173] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0174] Step 3: Coat a thin film solution on the upper and lower surfaces of the aluminum foil blank obtained in Step 2 and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methylcellulose, and polyvinyl alcohol; the coating method is screen printing; the thickness of the protective film layer is 10 μm.

[0175] Step 4: Sinter the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering 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 620°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.

[0176] Step 5: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 4, 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 5 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 200 V.

[0177] Example 6

[0178] 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina, titanium dioxide, and barium titanate are all 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 0.6%, 0.2%, and 0.2% respectively.

[0179] Step 2: Coat the aluminum-containing 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 20 μm, and the thickness of the dried aluminum-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0180] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and polyvinyl alcohol; the coating method is screen printing; the thickness of the protective film layer is 10 μm.

[0181] Step 4: Roll the aluminum foil blank with a protective film layer obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer 2 times with the length direction of the aluminum foil blank at an angle of 70° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer 2 times with the length direction of the aluminum foil blank at an angle of 110° to the axis direction of the roll; the roll reduction amount during the rolling process is 15 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0182] Step 5: Sinter the rolled aluminum foil obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 620 °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 is completed.

[0183] Step 6: Perform boiling water treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 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.

[0184] 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 8 is 1 time, and the number of transverse folding times is 3 times; the number of longitudinal folding times of the anode foil obtained in Example 6 is 136 times, and the number of transverse folding times is 72 times.

[0185] Comparative Example 9

[0186] 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, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 10%.

[0187] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 55 μm.

[0188] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is scraper coating; the thickness of the protective film layer is 30 μm.

[0189] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell furnace, and the sintering process is as follows: First, heat from room temperature to 500°C at a heating rate of 15°C / min in air and hold for 4 h; then heat to 640°C at a heating rate of 3°C / min in nitrogen and hold for 4 h, and cool with the furnace after the holding ends.

[0190] Step 5: Perform boiling water treatment and formation treatment on the sintered foil obtained in Step 4. 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 time is 10 min; the formation treatment uses a boric acid solution of 100 g / L and the formation voltage is 700 V.

[0191] Example 7

[0192] 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, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 10%.

[0193] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 55 μm.

[0194] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is knife coating; the thickness of the protective film layer is 30 μm.

[0195] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 2 times with the length direction of the aluminum foil blank at an angle of 60° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 2 times with the length direction of the aluminum foil blank at an angle of 110° to the axis direction of the roll; the reduction of the roll in the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a four-high rolling mill.

[0196] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 640 °C in nitrogen at a heating rate of 3 °C / min and hold for 4 h, and then cool with the furnace after the holding ends.

[0197] Step 6: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 700 V.

[0198] When carrying out the folding strength test 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 9 is 12 times, and the number of transverse folding times is 15 times; the number of longitudinal folding times of the anode foil obtained in Example 7 is 109 times, and the number of transverse folding times is 70 times.

[0199] Comparative Example 10

[0200] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), binder (ethyl cellulose), and 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, ceramic powder alumina, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina and titanium dioxide are both 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 3.5% and 1.5% respectively.

[0201] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper surface and the lower surface is 50 μm.

[0202] Step 3: Coat the upper surface and the lower surface of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is screen printing; the thickness of the protective film layer is 20 μm.

[0203] Step 4: Sinter the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: First, heat from room temperature to 450°C at a heating rate of 3°C / min in air and hold for 6 h; then heat to 630°C at a heating rate of 15°C / min in vacuum and hold for 10 h, and cool with the furnace after the holding ends.

[0204] Step 5: Perform water boiling treatment and forming treatment on the sintered foil obtained in Step 4, 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 5 min; the forming treatment uses a boric acid solution with a concentration of 100 g / L, and the forming voltage is 700 V.

[0205] Example 8

[0206] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate, ethylene glycol, propylene glycol, and glycerol), binder (ethyl cellulose), 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, ceramic powder alumina, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina and titanium dioxide are both 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 3.5% and 1.5% respectively.

[0207] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper surface and the lower surface is 50 μm.

[0208] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is screen printing; the thickness of the protective film layer is 20 μm.

[0209] Step 4: Roll the aluminum foil blank with a protective film layer obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer 15 times with the length direction of the aluminum foil blank with a protective film layer at an angle of 20° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer 15 times with the length direction of the aluminum foil blank with a protective film layer at an angle of 135° to the axis direction of the roll; the roll reduction amount during the rolling process is 5 μm; the roll diameter is 300 mm; the rolling mill is a two-high rolling mill.

[0210] Step 5: Sinter the rolled aluminum foil obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 630 °C in vacuum at a heating rate of 15 °C / min and hold for 10 h, and cool with the furnace after the holding ends.

[0211] Step 6: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 5 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.

[0212] 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 11 times, and the number of transverse folding times is 14 times; the number of longitudinal folding times of the anode foil obtained in Example 8 is 161 times, and the number of transverse folding times is 106 times.

[0213] Comparative Example 11

[0214] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl acetate, propylene glycol, and glycerol), binder (polyvinyl butyral), additives (organosilicon 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina, titanium dioxide, and barium titanate are 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 0.2%, 0.3%, and 0.5% respectively.

[0215] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper, and then dry it. After flipping it 180°, coat the aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 55 μm.

[0216] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methylcellulose, and polyvinyl alcohol; the coating method is scraper coating; the thickness of the protective film layer is 25 μm.

[0217] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell furnace, and the sintering 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 620°C in nitrogen at a heating rate of 20°C / min and hold for 6 h, and then cool with the furnace after the holding ends.

[0218] Step 5: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 4. 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.

[0219] Example 9

[0220] 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:150 to obtain an aluminum-containing 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 particle sizes of alumina, titanium dioxide, and barium titanate are 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 0.2%, 0.3%, and 0.5% respectively.

[0221] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper, and then dry it. After flipping it 180°, coat the aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 55 μm.

[0222] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and polyvinyl alcohol; the coating method is blade coating; the thickness of the protective film layer is 25 μm.

[0223] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at a 45° angle to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at a 160° angle to the axis direction of the roll; the roll reduction amount during the rolling process is 10 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0224] Step 5: Sinter the rolled aluminum foil obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: First, heat from room temperature to 500 °C at a heating rate of 20 °C / min in air and hold for 8 h; then heat to 620 °C at a heating rate of 20 °C / min in nitrogen and hold for 6 h, and then cool with the furnace after the holding ends.

[0225] Step 6: Perform boiling water treatment and formation treatment on the sintered foil obtained in Step 5, 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 15 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 700 V.

[0226] 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 11 is 13 times, and the number of transverse folding times is 12 times; the number of longitudinal folding times of the anode foil obtained in Example 9 is 97 times, and the number of transverse folding times is 98 times.

[0227] Comparative Example 12

[0228] 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 dispersant triethanolamine) 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, alumina ceramic powder) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 5%.

[0229] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 50 μm.

[0230] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the thickness of the protective film layer is 15 μm.

[0231] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering 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 610°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.

[0232] Step 5: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 4, 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.

[0233] Example 10

[0234] 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 dispersant triethanolamine) 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, ceramic powder alumina) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 5%.

[0235] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 50 μm.

[0236] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the thickness of the protective film layer is 15 μm.

[0237] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at a 45° angle to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at a 135° angle to the axis direction of the roll; the reduction of the roll in the rolling process is 5 μm; the roll diameter is 200 mm; the rolling mill is a three-roll rolling mill.

[0238] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 610 °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.

[0239] Step 6: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 chemical conversion treatment uses a boric acid solution with a concentration of 100 g / L, and the chemical conversion voltage is 520 V.

[0240] When carrying out the folding strength test 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 12 is 1 time, and the number of transverse folding times is 1 time; the number of longitudinal folding times of the anode foil obtained in Example 10 is 194 times, and the number of transverse folding times is 163 times.

[0241] Comparative Example 13

[0242] 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, ceramic powder alumina and titanium dioxide) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina and titanium dioxide are 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 0.7% and 0.3% respectively.

[0243] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 55 μm.

[0244] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is scraper coating; the thickness of the protective film layer is 15 μm.

[0245] Step 4: Sinter the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The sintering is carried out in a bell furnace, and the sintering 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 620°C in argon at a heating rate of 3°C / min and hold for 4 h, and cool with the furnace after the holding ends.

[0246] Step 5: Perform boiling water treatment and formation treatment on the sintered foil obtained in Step 4, 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 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.

[0247] Example 11

[0248] 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, ceramic powder alumina and titanium dioxide) in a mass ratio of 100:150 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of alumina and titanium dioxide is 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are 0.7% and 0.3% respectively.

[0249] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 55 μm.

[0250] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is knife coating; the thickness of the protective film layer is 15 μm.

[0251] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 20 times with the length direction of the aluminum foil blank at an angle of 20° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 20 times with the length direction of the aluminum foil blank at an angle of 110° to the axis direction of the roll; the reduction of the roll in the rolling process is 10 μm; the roll diameter is 65 mm; the rolling mill is a four-high rolling mill.

[0252] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 620 °C in argon at a heating rate of 3 °C / min and hold for 4 h, and then cool with the furnace after the holding ends.

[0253] Step 6: Perform boiling water treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 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.

[0254] 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 13 is 2 times, and the number of transverse bends is 3 times; the number of longitudinal bends of the anode foil obtained in Example 11 is 169 times, and the number of transverse bends is 81 times.

[0255] Comparative Example 14

[0256] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate and ethylene glycol), the binder (ethyl cellulose and polyvinyl butyral), and the additives (organic silicon defoamer and silane coupling agent) in a mass ratio of 50:50:6:2:0.5:5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:200 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina, titanium dioxide, and barium titanate are 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 3%, 1%, and 1% respectively.

[0257] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0258] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methylcellulose, and polyvinyl alcohol; the coating method is scraper coating; the thickness of the protective film layer is 25 μm.

[0259] Step 4: Sinter the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering 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 640°C in vacuum at a heating rate of 5°C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0260] Step 5: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 4. 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 formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 200 V.

[0261] Example 12

[0262] Step 1: Mix and stir evenly the solvent (diethylene glycol butyl ether acetate and ethylene glycol), binder (ethyl cellulose and polyvinyl butyral), additives (organic silicon defoamer and silane coupling agent) in a mass ratio of 50:50:6:2:0.5:5 to obtain a mixed solution. Mix and stir evenly the mixed solution and the solid aluminum-containing powder (aluminum powder, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:200 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina, titanium dioxide, and barium titanate are 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 3%, 1%, and 1% respectively.

[0263] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 60 μm.

[0264] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and polyvinyl alcohol; the coating method is knife coating; the thickness of the protective film layer is 25 μm.

[0265] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 2 times with the length direction of the aluminum foil blank at an angle of 70° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at an angle of 160° to the axis direction of the roll; the reduction of the roll in the rolling process is 15 μm; the roll diameter is 100 mm; the rolling mill is a four-high rolling mill.

[0266] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 640 °C in vacuum at a heating rate of 5 °C / min and hold for 12 h, and then cool with the furnace after the holding ends.

[0267] Step 6: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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.

[0268] 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 14 is 5 times, and the number of transverse folding times is 3 times; the number of longitudinal folding times of the anode foil obtained in Example 12 is 129 times, and the number of transverse folding times is 67 times.

[0269] Comparative Example 15

[0270] 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, alumina ceramic powder) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 1%.

[0271] Step 2: Coat the aluminum-containing 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 aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 55 μm.

[0272] Step 3: Coat a thin film solution on the upper and lower surfaces of the aluminum foil blank obtained in Step 2 and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the thickness of the protective film layer is 30 μm.

[0273] Step 4: Sinter the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The sintering is carried out in a bell furnace, and the sintering 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 620°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.

[0274] Step 5: Carry out water boiling treatment and forming treatment on the sintered foil obtained in Step 4. 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.

[0275] Example 13

[0276] 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, alumina ceramic powder) in a mass ratio of 100:80 to obtain a protective film layer; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of the alumina is 0.5 μm to 10 μm, and the mass fraction of the alumina in the solid aluminum-containing powder is 1%.

[0277] Step 2: Coat the protective film layer 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 protective film layer 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 dried protective film layer coated on both the upper and lower surfaces is 55 μm.

[0278] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose and polyvinylpyrrolidone; the coating method is screen printing; the thickness of the protective film layer is 30 μm.

[0279] Step 4: Roll the aluminum foil blank with a protective film layer obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer 20 times with the length direction of the aluminum foil blank at a 60° angle to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer 20 times with the length direction of the aluminum foil blank at a 160° angle to the axis direction of the roll; the roll reduction amount during the rolling process is 15 μm; the roll diameter is 600 mm; the rolling mill is a two-high rolling mill.

[0280] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 620 °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.

[0281] Step 6: Carry out water boiling treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 700 V.

[0282] 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 15 is 2 times, and the number of transverse folding times is 4 times; the number of longitudinal folding times of the anode foil obtained in Example 13 is 158 times, and the number of transverse folding times is 109 times.

[0283] Comparative Example 16

[0284] 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, ceramic powder alumina, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of alumina and titanium dioxide is 0.5 μm to 10 μm, and the mass fractions of alumina and titanium dioxide in the solid aluminum-containing powder are both 1%.

[0285] Step 2: Coat the aluminum-containing 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 aluminum-containing 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-containing slurry coated on both the upper and lower surfaces after drying is 60 μm.

[0286] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is scraper coating; the thickness of the protective film layer is 15 μm.

[0287] Step 4: Sinter the aluminum foil blank with a protective film layer obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering 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 630°C in argon at a heating rate of 5°C / min and hold for 12 h, and cool with the furnace after the holding ends.

[0288] Step 5: Perform water boiling treatment and forming treatment on the sintered foil obtained in Step 4, 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.

[0289] Example 14

[0290] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, and glycerol), the binder polyvinyl butyral, and the additives (organic silicon 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, ceramic powder alumina, and titanium dioxide) in a mass ratio of 100:250 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle size of alumina and titanium dioxide is 0.5 μm to 10 μm, and the mass fraction of alumina and titanium dioxide in the solid aluminum-containing powder is 1% for both.

[0291] Step 2: Coat the aluminum-containing 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 aluminum-containing 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-containing slurry coated on both the upper and lower surfaces after drying is 60 μm.

[0292] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution, and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of polyethylene glycol; the coating method is knife coating; the thickness of the protective film layer is 15 μm.

[0293] Step 4: Roll the aluminum foil blank with a protective film layer obtained in Step 3. The rolling method is diagonal rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer 10 times with the length direction of the aluminum foil blank at an angle of 20° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer 10 times with the length direction of the aluminum foil blank at an angle of 160° to the axis direction of the roll; the roll reduction amount during the rolling process is 5 μm; the roll diameter is 500 mm; the rolling mill is a two-high rolling mill.

[0294] Step 5: Sinter the rolled aluminum foil obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 630 °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 is completed.

[0295] Step 6: Perform boiling water treatment and chemical conversion treatment on the sintered foil obtained in Step 5, 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 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.

[0296] 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 7 times, and the number of transverse folding times is 12 times; the number of longitudinal folding times of the anode foil obtained in Example 14 is 145 times, and the number of transverse folding times is 70 times.

[0297] Comparative Example 17

[0298] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol), binder (ethyl cellulose), and additive (organosilicon 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:80 to obtain an aluminum-containing slurry; among them, the particle size of the aluminum powder is 0.5 μm to 5 μm, the mass purity is 99.99%, the particle sizes of alumina, titanium dioxide, and barium titanate are all 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 2.5%, 1%, and 1.5% respectively.

[0299] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper, and then dry it. After turning it over by 180°, coat the aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 50 μm.

[0300] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a thin film solution and dry it to obtain a protective film layer. The thin film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methylcellulose, and polyvinyl alcohol; the coating method is screen printing; the thickness of the protective film layer is 10 μm.

[0301] Step 4: Sinter the aluminum foil with a protective film obtained in Step 3. The sintering is carried out in a bell-type furnace, and the sintering process is as follows: First, heat from room temperature to 300°C at a heating rate of 1°C / min in air and hold for 1 h; then heat to 650°C at a heating rate of 20°C / min in nitrogen and hold for 6 h, and then cool with the furnace after the holding ends.

[0302] Step 5: Perform boiling water treatment and formation treatment on the sintered foil obtained in Step 4, 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 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.

[0303] Example 15

[0304] Step 1: Mix and stir evenly the solvent (terpineol, diethylene glycol butyl ether acetate, ethylene glycol), binder (ethyl cellulose), and additive (organosilicon 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, ceramic powder alumina, titanium dioxide, and barium titanate) in a mass ratio of 100:80 to obtain an aluminum-containing 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 particle sizes of alumina, titanium dioxide, and barium titanate are all 0.5 μm to 10 μm, and the mass fractions of alumina, titanium dioxide, and barium titanate in the solid aluminum-containing powder are 2.5%, 1%, and 1.5% respectively.

[0305] Step 2: Coat the aluminum-containing slurry obtained in Step 1 on the upper surface of the aluminum foil substrate with a scraper, and then dry it. After turning it over by 180°, coat the aluminum-containing 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 dried aluminum-containing slurry coated on both the upper and lower surfaces is 50 μm.

[0306] Step 3: Coat the upper and lower surfaces of the aluminum foil blank obtained in Step 2 with a film solution, and dry it to obtain a protective film layer. The film solution is an aqueous solution of hydroxyethyl cellulose, hydroxypropyl methylcellulose, and polyvinyl alcohol; the coating method is screen printing; the thickness of the protective film layer is 10 μm.

[0307] Step 4: Roll the aluminum foil blank with a protective film layer on its surface obtained in Step 3. The rolling method is skew rolling, and the rolling process is as follows: First, roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at an angle of 40° to the axis direction of the roll, and then roll the aluminum foil blank with a protective film layer on its surface 10 times with the length direction of the aluminum foil blank at an angle of 110° to the axis direction of the roll; the reduction of the roll in the rolling process is 10 μm; the roll diameter is 400 mm; the rolling mill is a two-high rolling mill.

[0308] Step 5: Sinter the rolled aluminum foil blank obtained in Step 4. The sintering is carried out in a bell-type furnace, and the sintering 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 650 °C in nitrogen at a heating rate of 20 °C / min and hold for 6 h, and cool with the furnace after the holding ends.

[0309] Step 6: Carry out water boiling treatment and formation treatment on the sintered foil obtained in Step 5, 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 5 min; the formation treatment uses a boric acid solution with a concentration of 100 g / L, and the formation voltage is 200 V.

[0310] When performing the folding strength test using a chuck with a radius of curvature of 3.5 mm, the number of longitudinal folding times of the anode foil obtained in Comparative Example 17 is 13 times, and the number of transverse folding times is 8 times; the number of longitudinal folding times of the anode foil obtained in Example 15 is 167 times, and the number of transverse folding times is 56 times.

[0311] The detection results of the folding performance of the anode foils prepared in Comparative Examples 1 - 17 and Examples 1 - 15 are shown in Table 1:

[0312] Table 1

[0313]

[0314] As can be seen from Table 1: For the anode foil prepared in Comparative Example 1 and processed by a roller disposed obliquely, the number of longitudinal bending times is 152, and the number of transverse bending times is 76; for the anode foil prepared in Comparative Example 2 and processed by a roller with balls rotatable about their own centers of spheres disposed on the circumferential surface thereof and disposed obliquely, the number of longitudinal bending times is 174, and the number of transverse bending times is 82; for the anode foil prepared in Example 1 and processed by skew rolling using a rolling mill, the number of longitudinal bending times is 185, and the number of transverse bending times is 92. When the number of processing times is the same, the number of bending times of the anode foil prepared in Example 1 is higher than those of the anode foils prepared in Comparative Example 1 and Comparative Example 2.

[0315] In addition, the transverse and longitudinal anti-bending performances of the anode foils without rolling treatment prepared in Comparative Examples 3 - 17 are relatively poor, and the number of their bending times is within 20; for the anode foils prepared in Examples 1 - 15 and processed by skew rolling using a rolling mill, the number of transverse bending times reaches more than 50, and the number of longitudinal bending times reaches more than 90. By comparing Comparative Examples 3 - 17 and Examples 1 - 15, it can be known that under the same test conditions, the number of bending times of the anode foils prepared in Examples 1 - 15 is increased by more than 400% compared with those of the anode foils prepared in Comparative Examples 3 - 17, greatly improving the transverse and longitudinal anti-bending performances of the anode foils and meeting the mechanical processing requirements. Therefore, the preparation method of the anode foil provided by the present disclosure can improve the anti-bending performance of the anode foil, thereby improving the overall performance of the device.

[0316] It should be noted that although the steps of the preparation method of the 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.

[0317] Those skilled in the art will readily conceive of other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which 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 regarded 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, characterized in that: include: Step S1: preparing an aluminum-containing slurry, wherein the aluminum-containing slurry comprises a mixed solution and a 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 ceramic powder; Step S2: providing an aluminum foil substrate, coating the aluminum-containing slurry on the surface of the aluminum foil substrate, and performing a drying process to form an aluminum foil blank; Step S3: coating a thin film solution on the surface of the aluminum foil blank, and performing a drying process to form a protective film layer on the surface of the 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 S4: using a rolling mill to perform a rolling process on the aluminum foil blank having the protective film layer by multiple oblique rolling to obtain an initial anode foil; The rolling process comprises: performing a first rolling process on the 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 aluminum foil blank; performing a second rolling process on the aluminum foil blank with the protective film layer, wherein the axis direction of the roller and the length direction of the aluminum foil blank are 110° to 160°; the diameter of the roller is 65 mm to 600 mm; Step S5: sintering the initial anode foil to remove the protective film layer to form a sintered foil.

2. The method for preparing an anode foil 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 S4, the 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: Performing a first rolling process on the aluminum foil blank having the protective film layer, wherein the first rolling process is to repeatedly roll the aluminum foil blank 2 to 20 times; The aluminum foil blank having the protective film layer is then subjected to a second rolling process, wherein the second rolling process is repeated rolling of the aluminum foil blank 2 to 20 times.

3. The method for preparing an anode foil according to claim 1, characterized in that: In step S3, a thin film solution is coated on the surface of the aluminum foil blank, and the method comprises: The aluminum foil blank is coated with the thin film solution on both sides by using a doctor blade coating or screen printing method; the thickness of the protective film layer on each side of the aluminum foil blank is the same, and the thickness of the protective film layer on each side of the aluminum foil blank is 5μm~30μm.

4. The method for preparing an anode foil according to claim 1, characterized in that: The mass fraction of the ceramic powder to the solid aluminum-containing powder is 1% to 10%; the mass ratio of the mixed solution to the solid aluminum-containing powder is 100:(80 to 250).

5. The method for preparing an anode foil according to claim 4, characterized in that: The ceramic powder is one or more of aluminum oxide, titanium dioxide, barium titanate, and strontium titanate; and the particle size of the ceramic powder is 0.5 μm to 10 μm.

6. The method for preparing an anode foil 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.

7. The method for preparing an anode foil 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-containing slurry to form aluminum slurry 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.

8. The method for preparing an anode foil according to claim 1, characterized in that: In step S5, the sintering process includes: In an air atmosphere, heating the initial anode foil 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 initial anode foil is continuously heated to 610° C. to 650° 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.

9. The method for preparing an anode foil according to claim 1, characterized in that: After step S5, 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; The intermediate anode foil is subjected to a chemical formation treatment to form an oxide layer on the intermediate anode foil to obtain a target anode foil, wherein a chemical formation voltage of the chemical formation treatment is 200V to 700V.

10. An aluminum electrolytic capacitor, characterized in that: The invention relates to an anode foil prepared by the preparation method according to any one of claims 1 to 9.

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