Electrode foil, preparation method thereof and aluminum electrolytic capacitor

Abstract

The invention belongs to the technical field of electrode materials, and particularly relates to an electrode foil and a preparation method thereof and an aluminum electrolytic capacitor, the electrode foil comprises a base material and a sintered layer formed by an aluminum sintered body and arranged on the surface of at least one side of the base material, and the sintered layer on each side is provided with cracks distributed in a gridding mode. The cracks extend from the surface of the side, far away from the base material, of the sintering layer to the surface of the base material, stress release of the electrode foil in multiple directions is achieved, the continuous obdurability of the electrode foil is improved, the electrode foil is not damaged, and therefore the electrode foil can not be damaged in the cutting, winding and riveting processes of the electrode foil. By means of the structure, stress cannot be concentrated at one point to be released, breakage and cracking of the electrode foil are reduced, the bending strength performance can be improved, the number of times of transverse and longitudinal bending is increased, and breakage and cracking are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and particularly relates to an electrode foil and a preparation method thereof, and an aluminum electrolytic capacitor. Background Art

[0002] Since the 1990s, with the continuous development of electronic information technology and the expansion of its application fields, aluminum electrolytic capacitors have continued to develop towards miniaturization, high performance and high reliability.

[0003] Laminated foil is a core raw material for capacitor electrode foils. Its surface area is 20% to 35% larger than that of traditional etched foil, and its production process is pollution-free. It is poised to gradually replace most traditional etched foils in the future, and its development prospects are promising. However, laminated foil currently suffers from poor strength and is prone to cracking, breaking, and burring during cutting, winding, and riveting, creating significant challenges in capacitor production. Summary of the Invention

[0004] The object of the present invention is to provide an electrode foil, a preparation method thereof, and an aluminum electrolytic capacitor. The electrode foil of the present invention has cracks distributed in a grid pattern, which can realize stress release in multiple directions of the electrode foil, increase the continuous toughness of the electrode foil and do not damage the electrode foil itself. Therefore, during the cutting, winding, and riveting processes of the electrode foil, the stress will not be concentrated at one point for release, thereby reducing the breakage and cracking of the electrode foil. Such a structure can improve the bending strength performance, increase the number of transverse and longitudinal bending times, and reduce breakage and cracking.

[0005] A first aspect of the present invention provides an electrode foil, which includes a substrate and a sintered layer composed of an aluminum sintered body on at least one side surface of the substrate, wherein the sintered layer on each side has cracks distributed in a grid pattern, and the cracks extend from the side surface of the sintered layer away from the substrate to the surface of the substrate.

[0006] In some embodiments of the present invention, the sintered layers are provided on two opposite surfaces of the substrate; based on the substrate, the cracks of the sintered layers on both sides are independently and asymmetrically distributed.

[0007] In some embodiments of the present invention, based on the horizontal surface of the sintered layer on one side, the tortoise shell crack includes a plurality of crack grids, the tortoise shell crack includes a plurality of transverse cracks and a plurality of longitudinal cracks, and the plurality of transverse cracks and the plurality of longitudinal cracks together constitute the plurality of crack grids.

[0008] In some embodiments of the present invention, each of the transverse cracks independently forms an angle of 0 to 45 degrees with the transverse axis.

[0009] In some embodiments of the present invention, each of the transverse cracks is independently a straight line or an irregular curve.

[0010] In some embodiments of the present invention, each of the longitudinal cracks independently forms an angle of 0 to 45 degrees with the longitudinal axis.

[0011] In some embodiments of the present invention, each of the longitudinal cracks is independently a straight line or an irregular curve.

[0012] In some embodiments of the present invention, in the sintered layer on each side, the crack lattices are independently complete or incomplete grids.

[0013] In some embodiments of the present invention, each of the crack grids is independently a regular or irregular grid.

[0014] In some embodiments of the present invention, in the sintered layers located on both sides, the multiple transverse axis cracks are independently and asymmetrically distributed.

[0015] In some embodiments of the present invention, in the sintered layers on both sides, the plurality of longitudinal cracks are independently and asymmetrically distributed.

[0016] In some embodiments of the present invention, in a complete crack lattice, based on the transverse axis direction of the horizontal surface, the width of each crack lattice is independently 40 μm to 300 μm.

[0017] In some embodiments of the present invention, in a complete crack lattice, the width of each crack lattice is independently 40 μm to 200 μm based on the longitudinal axis direction of the horizontal surface.

[0018] In some embodiments of the present invention, in the sintered layer on each side, at least 10% of the cracks have a depth less than the thickness of the sintered layer.

[0019] In some embodiments of the present invention, the thickness of the sintered layer on each side is independently 10 μm to 200 μm.

[0020] In some embodiments of the present invention, the thickness of the substrate is 20 μm to 40 μm.

[0021] In some embodiments of the present invention, the substrate is selected from aluminum foil.

[0022] The second aspect of the present invention also provides a method for preparing the electrode foil described in the first aspect, the preparation method comprising: mixing aluminum powder, a cross-linking agent and a solvent to form a slurry; coating the slurry on at least one side surface of a substrate, and sequentially performing drying and sintering treatments to obtain the electrode foil.

[0023] In some embodiments of the present invention, in the slurry, the mass of the solvent is 30% to 70% of the mass of the aluminum powder.

[0024] In some embodiments of the present invention, in the slurry, the mass of the cross-linking agent is 0.1% to 10% of the mass of the aluminum powder.

[0025] In some embodiments of the present invention, the viscosity of the slurry is 100 mPa·s to 40,000 mPa·s.

[0026] In some embodiments of the present invention, the cross-linking agent includes one or more of an organic silicone resin, an organic fluorine polymer, a fluoroolefin resin, an acrylic resin, and a cellulose resin.

[0027] In some embodiments of the present invention, the solvent includes one or more of pure water, starch solution, glycerol, ethylene glycol, terpineol, and ketones.

[0028] In some embodiments of the present invention, the particle size D50 of the aluminum powder is 1 μm to 20 μm.

[0029] In some embodiments of the present invention, the drying temperature is 50°C to 150°C.

[0030] In some embodiments of the present invention, the drying process lasts for 1 min to 30 min.

[0031] In some embodiments of the present invention, the sintering temperature is 520°C to 670°C.

[0032] In some embodiments of the present invention, the sintering treatment time is 1 hour to 50 hours.

[0033] In some embodiments of the present invention, the heating rate of the sintering process is 1° C. / min to 20° C. / min.

[0034] In some embodiments of the present invention, the sintering process is performed under an inert protective atmosphere.

[0035] In some embodiments of the present invention, the inert protective atmosphere is any one of nitrogen atmosphere, helium atmosphere, argon atmosphere, and neon atmosphere.

[0036] The third aspect of the present invention further provides an aluminum electrolytic capacitor, which includes the electrode foil described in the first aspect or the electrode foil prepared by the preparation method described in the second aspect.

[0037] The electrode foil of the present invention has cracks distributed in a grid pattern, which can realize stress release in multiple directions of the electrode foil, increase the continuous toughness of the electrode foil and do not damage the electrode foil itself. Therefore, during the cutting, winding and riveting processes of the electrode foil, the stress will not be concentrated at one point for release, reducing the breakage and cracking of the electrode foil. Such a structure can improve the bending strength performance, increase the number of horizontal and vertical bending times, and reduce breakage and cracking.

[0038] The preparation process of the electrode foil of the present invention is simple and easy to operate, and the prepared electrode foil has high bending strength and plasticity.

[0039] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 This is an electron microscope image of the horizontal surface of the sintered layer in the electrode foil prepared in Example 1 of the present invention.

[0042] Figure 2 for Figure 1 Longitudinal cross-section of a crack perpendicular to the horizontal axis.

[0043] Figure 3 This is an electron microscope image of the horizontal surface of the sintered layer in the electrode foil prepared in Comparative Example 1 of the present invention.

[0044] Figure 4 for Figure 3 Longitudinal cross-section of a crack perpendicular to the horizontal axis. DETAILED DESCRIPTION

[0045] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0046] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0047] In the description of the embodiments of the present invention, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present invention, "plurality" means more than two, unless otherwise specifically defined.

[0048] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] In the description of the embodiments of the present invention, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exists simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0050] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0051] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0052] At present, most of the cracks on the plane of the existing sintered layer are distributed horizontally. At the same time, the depth of the cracks will penetrate into the substrate during the chemical formation. The cracks at the symmetrical position destroy the continuity of the electrode foil, resulting in the weakest mechanical properties of the electrode foil at this position. In the subsequent processing process, such as winding, unwinding and subsequent chemical treatment, unfavorable conditions such as breakage and corrosion will occur.

[0053] The first aspect of the present invention provides an electrode foil, Figure 1 and Figure 2 According to the introduction, the electrode foil includes a substrate and a sintered layer composed of an aluminum sintered body on at least one side surface of the substrate. The sintered layer on each side has cracks distributed in a grid pattern, and the cracks extend from the side surface of the sintered layer away from the substrate to the surface of the substrate.

[0054] In an embodiment of the present invention, a sintered layer is provided on one side of the substrate, i.e., a single side, or on two opposite sides of the substrate, i.e., both sides. The sintered layer is composed of an aluminum sintered body, and the sintered layer on each side has cracks distributed in a grid pattern, which can effectively release the internal stress of the sintered layer caused by processing in all directions, and can further improve the multi-directional bending strength of the electrode foil, especially can greatly improve the toughness along the transverse axis of the electrode foil, improve the performance of cutting, winding and riveting of the electrode foil, and reduce the risk of broken foil.

[0055] In an embodiment of the present invention, the cracks extend from the side surface of the sintered layer away from the substrate to the surface of the substrate, and the depth of some cracks is less than the thickness of the sintered layer. As a result, the cracks on the sintered layer do not all penetrate into the substrate itself, which can release stress in multiple directions of the electrode foil, increase the strength and toughness of the electrode foil and do not damage the electrode foil itself. Therefore, during the process of cutting, winding and riveting the electrode foil, the stress will not be concentrated at one point for release, reducing the breakage and cracking of the electrode foil, improving the bending strength, increasing the number of transverse and longitudinal cracks, and reducing breakage and cracking.

[0056] See also Figure 1As shown, based on the horizontal surface of the sintered layer on one side, the tortoise crack includes multiple crack grids, thereby making the tortoise cracks distributed in a grid. Specifically, the tortoise cracks include multiple transverse cracks and multiple longitudinal cracks, and the multiple transverse cracks and the multiple longitudinal cracks together constitute multiple crack grids.

[0057] In an embodiment of the present invention, based on the horizontal surface of the sintered layer on one side, each transverse crack independently forms an angle of 0 to 45° with the transverse axis, that is, each transverse crack independently can be parallel to the transverse axis or form a certain angle with the transverse axis; each transverse crack independently can be a straight line or an irregular curve.

[0058] In an embodiment of the present invention, based on the horizontal surface of the sintered layer on one side, each longitudinal crack independently forms an angle of 0 to 45° with the longitudinal axis, that is, each longitudinal crack independently can be parallel to the longitudinal axis or form a certain angle with the longitudinal axis; each longitudinal crack independently can be a straight line or an irregular curve.

[0059] In the embodiment of the present invention, based on the horizontal surface of the sintered layer on one side, each crack grid can independently be a regular grid or an irregular grid.

[0060] In the embodiment of the present invention, based on the horizontal surface of the sintered layer on one side, the cracks in a grid-like distribution can each independently be cracks in a regular grid-like distribution or cracks in an irregular grid-like distribution.

[0061] In the embodiment of the present invention, based on the horizontal surface of the sintered layer on one side, each crack grid can be independently a complete grid or an incomplete grid.

[0062] In an embodiment of the present invention, in a complete crack grid, the width of each crack grid in the transverse direction relative to the horizontal surface is independently 40 μm to 300 μm. The width of the crack grid in the transverse direction provided by the present invention can be a range consisting of any two values within the above range, for example, 40 μm to 150 μm, 150 μm to 300 μm, and so on. The width of the crack grid in the transverse direction provided by the present invention can also be one of 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm, 300μm or any value that meets the above range.

[0063] In an embodiment of the present invention, in a complete crack grid, based on the longitudinal axis direction of the horizontal surface, the width of each crack grid is independently 40μm to 200μm. The width of the crack grid in the longitudinal axis direction provided by the present invention can be a value in the interval consisting of any two values within the above range, for example, it can be 40μm to 150μm, or it can be 150μm to 200μm, and so on. The width of the crack grid in the longitudinal axis direction provided by the present invention can also be one of 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, or any value that meets the above range.

[0064] See also Figure 2 As shown, the sintered layer on either side of the substrate has cracks distributed in a grid pattern, and based on the substrate, the cracks on both sides are independently and asymmetrically distributed.

[0065] In some embodiments of the present invention, in the sintered layers on both sides, a plurality of transverse cracks are independently and asymmetrically distributed.

[0066] In some embodiments of the present invention, in the sintered layers on both sides, a plurality of longitudinal cracks are independently and asymmetrically distributed.

[0067] In some embodiments of the present invention, the cracks extend from the surface of the side of the sintered layer away from the substrate to the surface of the substrate, and the depth of at least 10% of the cracks is less than the thickness of the sintered layer, that is, at least 10% of the cracks on the sintered layer do not penetrate into the substrate itself. In the embodiment of the present invention, the proportion of cracks that do not penetrate into the substrate itself can be a value in the interval composed of any two values within the above range, such as 10% to 50%, or 50% to 100%, and so on. For example, in the embodiment of the present invention, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% of the cracks have a depth less than the thickness of the sintered layer.

[0068] In some embodiments of the present invention, the thickness of the sintered layer on each side is independently 10 μm to 200 μm. The thickness of the sintered layer provided by the present invention can be a range consisting of any two values within the above range, for example, 10 μm to 60 μm, or 60 μm to 200 μm, and so on. The thickness of the sintered layer provided by the present invention can also be one of 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm, 200μm or any value that meets the above range.

[0069] In some embodiments of the present invention, the thickness of the substrate is 20 μm to 40 μm. The thickness of the substrate provided by the present invention can be a value within the range formed by any two values within the above range, for example, it can be 20 μm to 30 μm, or 30 μm to 40 μm, and so on. The thickness of the substrate provided by the present invention can also be one of 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, 32 μm, 35 μm, 38 μm, 40 μm, or any value that meets the above range.

[0070] In an embodiment of the present invention, the substrate may be a substrate used as an electrode foil for an aluminum electrolytic capacitor, such as a substrate known in the art.

[0071] In some embodiments of the present invention, the substrate may be selected from aluminum foil of pure aluminum or aluminum alloy, but is not limited to plain foil, cathode and anode foil, and the like.

[0072] The second aspect of the present invention provides a method for preparing the electrode foil described in the first aspect. The key to this preparation method is to mix aluminum powder, a cross-linking agent and a solvent to form a slurry, apply the slurry on at least one side of the substrate, and perform drying and sintering in sequence to obtain the electrode foil.

[0073] In the embodiment of the present invention, the method for preparing the electrode foil is specifically carried out according to the following steps.

[0074] Preparation of slurry

[0075] In an embodiment of the present invention, aluminum powder is used as raw material powder, which is mixed with a cross-linking agent and a solvent to form a slurry.

[0076] In some embodiments of the present invention, the viscosity of the slurry is 100 mPa·s to 40,000 mPa·s. The viscosity of the slurry provided by the present invention can be a value in an interval consisting of any two values within the above range, for example, it can be 100 mPa·s to 8,000 mPa·s, 8,000 mPa·s to 15,000 mPa·s, or 15,000 mPa·s to 40,000 mPa·s, and so on. For example, the viscosity of the slurry can be 100 mPa·s, 200 mPa·s, 300 mPa·s, 400 mPa·s, 500 mPa·s, 600 mPa·s, 700 mPa·s, 800 mPa·s, 900 mPa·s, 1000 mPa·s, 1100 mPa·s, 1200 mPa·s, 1300 mPa·s, 1400 mPa·s, 1500 mPa·s, 1600 mPa·s, 1700 mPa·s, 1800 mPa·s, 1900 mPa·s, 2000 mPa·s, 2100 mPa·s, 2200 mPa·s, 2300 mPa·s, 2400 mPa·s, 2500 mPa·s, 2600 mPa·s, 2700 mPa·s, 2800 mPa·s, 2900 mPa·s, 3000 mPa·s, 3100 mPa·s, 3200 mPa·s, 3300 mPa·s, 3400 mPa·s, 3500 mPa·s, 3600 mPa·s, 3700 mPa·s, 3800 mPa·s, 3900 mPa·s, 4000 mPa·s, 4100 mPa·s, 4200 mPa·s, 4300 mPa·s, 4400 mPa·s, 4500 mPa·s, 4600 mPa·s, 4700 mPa·s, 4800 mPa·s, 4900 mPa·s, 5000 mPa·s, 5100 mPa One of mPa·s, 1800mPa·s, 1900mPa·s, 2000mPa·s, 3000mPa·s, 4000mPa·s, 5000mPa·s, 6000mPa·s, 7000mPa·s, 8000mPa·s, 9000mPa·s, 10000mPa·s, 20000mPa·s, 30000mPa·s, and 40000mPa·s, or any value that meets the above range.

[0077] In some embodiments of the present invention, the particle size D50 of the aluminum powder is 1 μm to 20 μm. The particle size D50 of the aluminum powder provided by the present invention can be a value in the interval consisting of any two values within the above range, for example, it can be 1 μm to 10 μm, or it can be 10 μm to 20 μm, and so on. Exemplarily, the particle size D50 of the aluminum powder can also be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or any value that meets the above range.

[0078] In some embodiments of the present invention, the purity of the aluminum powder is ≥99.50%.

[0079] In some embodiments of the present invention, the mass of the solvent in the slurry is 30% to 70% of the mass of the aluminum powder. The mass of the solvent provided by the present invention can be a range consisting of any two values within the above range, for example, 30% to 50%, or 50% to 70%, and so on. Illustratively, the mass of the solvent can be one of 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70% of the mass of the aluminum powder, or any value that meets the above range.

[0080] In some embodiments of the present invention, the solvent includes one or more of pure water, starch solution, glycerol, ethylene glycol, terpineol, and ketones.

[0081] In some embodiments of the present invention, the solvent is pure water.

[0082] In some embodiments of the present invention, the starch solution may be, but is not limited to, an alcohol solution of starch, such as an ethylene glycol solution of starch.

[0083] In some embodiments of the present invention, the mass of the crosslinking agent in the slurry is 0.1% to 10% of the mass of the aluminum powder. The mass of the crosslinking agent provided by the present invention can be a value between any two values within the above range, for example, it can be 0.1% to 1% of the mass of the aluminum powder, or it can be 1% to 10% of the mass of the aluminum powder, and so on. Exemplarily, the mass of the crosslinking agent can be one of 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the aluminum powder, or any value that meets the above range.

[0084] In the embodiment of the invention, the slurry is prepared by mixing a cross-linking agent and a solvent, and the ratio of the cross-linking agent, the solvent and the aluminum powder is designed, thereby achieving the generation of the cracks.

[0085] In some embodiments of the present invention, the crosslinking agent includes one or more of an organic silicone resin, an organic fluorine polymer, a fluoroolefin resin, an acrylic resin, and a cellulose resin.

[0086] As some embodiments of the present invention, the organic fluorine polymer includes polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), polytetrafluoroethylene, etc., which can be selected and set according to actual needs.

[0087] In some embodiments of the present invention, the fluoroolefin resin includes polychlorotrifluoroethylene, polyvinylidene fluoride, and the like.

[0088] As some embodiments of the present invention, the organic silicone resin includes methyl silicone resin, fluorosilicone resin, methylphenyl silicone resin, vinyl silicone resin, etc., which can be selected and set according to actual needs.

[0089] In the present invention, aluminum powder is added to a mixed solution formed by the above-mentioned solvent (for example, pure water) and a cross-linking agent to obtain a slurry. During the drying process, the solvent in the slurry evaporates and cracks are generated. When aluminum powder is added to a colloid prepared with an oily solvent (for example, phthalate), since the oily solvent cannot be removed by evaporation, only horizontal cracks can be generated.

[0090] In an embodiment of the present invention, the cracks generated by the evaporation of the solvent in the slurry extend from the surface of the side of the sintered layer away from the substrate to the surface of the substrate, and at least 10% of the cracks have a depth less than the thickness of the sintered layer, that is, at least 10% of the cracks on the sintered layer do not penetrate into the substrate itself. In an embodiment of the present invention, the proportion of cracks that do not penetrate into the substrate itself can be a value in the interval composed of any two values within the above range, such as 10% to 50%, or 50% to 100%, and so on. For example, in an embodiment of the present invention, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% of the cracks have a depth less than the thickness of the sintered layer.

[0091] coating

[0092] In an embodiment of the present invention, the slurry is coated on at least one surface of a substrate to form a coating layer on the surface of the substrate.

[0093] In some embodiments of the present invention, the single-sided coating thickness can also be understood as the single-sided coating thickness controlled within a range of 10 μm to 200 μm. The single-sided coating thickness provided by the present invention can be a value within the interval consisting of any two values within the above range, for example, 10 μm to 60 μm, 60 μm to 80 μm, 80 μm to 200 μm, and so on. The thickness of the single-sided coating provided by the present invention can be one of 10μm, 20μm, 30μm, 40μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 52μm, 55μm, 58μm, 60μm, 62μm, 65μm, 68μm, 70μm, 72μm, 75μm, 78μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm or any value that meets the above range.

[0094] In some embodiments of the present invention, the substrate is selected from aluminum foil, but is not limited to plain foil, cathode and anode foil, and the like.

[0095] In some embodiments of the present invention, the thickness of the substrate is 20 μm to 40 μm. The thickness of the substrate provided by the present invention can be a value of an interval consisting of any two values within the above range, for example, it can be 20 μm to 35 μm, or it can be 35 μm to 40 μm, and so on. The thickness of the substrate provided by the present invention can also be one of 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm or any value that meets the above range value.

[0096] In some embodiments of the present invention, the mixed slurry is introduced into a coating machine and coated on the surface of the substrate to form a coating on the surface of the substrate.

[0097] Drying treatment

[0098] In an embodiment of the present invention, the substrate with the coating obtained after coating is subjected to a drying treatment.

[0099] In some embodiments of the present invention, the temperature of the drying process is 50°C to 150°C. The drying temperature provided by the present invention can be a value in the interval consisting of any two values within the above range, for example, it can be 50°C to 100°C, or it can be 100°C to 150°C, and so on. The drying temperature provided by the present invention can also be one of 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or any value that meets the above range.

[0100] In some embodiments of the present invention, the time of drying process is 1min~30min. The time of drying process provided by the present invention can be the value of the interval composed of any two values in the above range, such as can be 1min~10min, also can be 10min~30min, and so on. The time of drying process provided by the present invention can also be 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min, 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min one or any numerical value that meets the above range value.

[0101] It should be noted that the "room temperature" in the present invention generally refers to a state where no active heating or cooling is performed. For example, in the embodiments of the present invention, the room temperature generally refers to 20°C to 40°C.

[0102] Sintering treatment

[0103] In an embodiment of the present invention, the substrate with the coating layer after the drying process is subjected to a sintering process.

[0104] In an embodiment of the present invention, the sintering process is performed under an inert protective atmosphere.

[0105] In some embodiments of the present invention, the inert protective atmosphere may be, but is not limited to, an inert atmosphere such as nitrogen, argon, helium, or neon.

[0106] In some embodiments of the present invention, the temperature of the sintering treatment may be 520°C to 670°C. The temperature of the sintering treatment provided by the present invention may be a value in the interval consisting of any two values within the above range, for example, it may be 520°C to 600°C, or it may be 600°C to 670°C, and so on. The temperature of the sintering treatment provided by the present invention may also be one of 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, or any value that meets the above range.

[0107] In some embodiments of the present invention, the sintering time may be 1 hour to 50 hours. The sintering time provided by the present invention may be a value between any two values within the above range, for example, 1 hour to 5 hours, or 5 hours to 50 hours, and so on. The sintering time provided by the present invention can also be one of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 31h, 32h, 33h, 34h, 35h, 36h, 37h, 38h, 39h, 40h, 41h, 42h, 43h, 44h, 45h, 46h, 47h, 48h, 49h, and 50h, or any value that meets the above range.

[0108] In some embodiments of the present invention, the heating rate of the sintering process is 1°C / min to 20°C / min. The heating rate of the sintering process provided by the present invention can be a value of an interval consisting of any two values within the above range, for example, it can be 1°C / min to 10°C / min, or it can be 10°C / min to 20°C / min, and so on. The heating rate of the sintering process provided by the present invention can also be one of 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min, 20°C / min or any value that meets the above range value.

[0109] In some embodiments of the present invention, argon is continuously introduced during the sintering process, and the substrate with the coating after drying is continuously heated to 520°C to 670°C at a rate of 1°C / min to 20°C / min and kept warm for 1 hour to 50 hours; after the end of the heat preservation, the electrode foil with cracks distributed in a grid pattern can be obtained by naturally cooling the substrate.

[0110] The third aspect of the present invention further provides an aluminum electrolytic capacitor, which includes the electrode foil described in the first aspect or the electrode foil prepared by the preparation method described in the second aspect.

[0111] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the amounts of the experimental reagents used, unless otherwise specified, are the amounts of reagents used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods. It should be further noted that the following description is merely exemplary and does not specifically limit the present invention.

[0112] Example 1

[0113] An electrode foil and a method for preparing the same. The steps for preparing the electrode foil are as follows:

[0114] 1) Prepare slurry using aluminum powder as raw material

[0115] Aluminum powder with a particle size D50 of 5 μm was added to a mixed solution of pure water (whose mass was 40% of the mass of the aluminum powder) and cellulose resin (whose mass was 3% of the mass of the aluminum powder), and stirred evenly to prepare a slurry with a viscosity of 2000±100 mPa·s.

[0116] 2) Coating

[0117] The prepared slurry was evenly coated on two opposite surfaces of an aluminum foil with a thickness of 25 μm, and the thickness of the coating on one side was controlled at 65 μm to obtain an aluminum foil with a coating on the surface.

[0118] 3) Drying

[0119] The obtained aluminum foil with the coating on the surface was dried at 120° C. for 15 minutes.

[0120] 4) Sintering treatment

[0121] The dried aluminum foil was sintered in an argon atmosphere at a heating rate of 10°C / min. After heating to 640°C, the foil was kept warm for 10 hours. After the heat preservation, the foil was naturally cooled to room temperature to obtain an electrode foil with grid-like cracks.

[0122] The electrode foil sintered in Example 1 was sampled and punched into 1 cm×5 cm samples using an aluminum foil punching machine. The samples were then subjected to a bending test using a bending machine.

[0123] Example 2

[0124] An electrode foil and a method for preparing the same. The steps for preparing the electrode foil are as follows:

[0125] 1) Prepare slurry using aluminum powder as raw material

[0126] Aluminum powder with a particle size D50 of 5 μm was added to a mixed solution of pure water (whose mass was 40% of the mass of the aluminum powder) and cellulose resin (whose mass was 3% of the mass of the aluminum powder), and stirred evenly to prepare a slurry with a viscosity of 2000±100 mPa·s.

[0127] 2) Coating

[0128] The prepared slurry was evenly coated on two opposite surfaces of an aluminum foil with a thickness of 25 μm, and the thickness of the coating on one side was controlled to be 50 μm to obtain an aluminum foil with a coating on the surface.

[0129] 3) Drying

[0130] The obtained aluminum foil with the coating on the surface was dried at 120° C. for 15 minutes.

[0131] 4) Sintering treatment

[0132] The dried aluminum foil was sintered in an argon atmosphere at a heating rate of 10°C / min. After heating to 650°C, it was kept warm for 15 hours. After the end of the heat preservation, it was naturally cooled to room temperature to obtain an electrode foil with grid-like cracks.

[0133] The electrode foil sintered in Example 2 was sampled and punched into 1 cm×5 cm samples using a punching machine, and then subjected to bending testing using a bending machine.

[0134] Example 3

[0135] An electrode foil and a method for preparing the same. The steps for preparing the electrode foil are as follows:

[0136] 1) Prepare slurry using aluminum powder as raw material

[0137] Aluminum powder with a particle size D50 of 8 μm was added to a mixed solution of pure water (whose mass was 40% of the mass of the aluminum powder) and cellulose resin (whose mass was 3% of the mass of the aluminum powder), and stirred evenly to prepare a slurry with a viscosity of 2000±100 mPa·s.

[0138] 2) Coating

[0139] The prepared slurry was evenly coated on two opposite surfaces of an aluminum foil with a thickness of 25 μm, and the thickness of the coating on one side was controlled at 65 μm to obtain an aluminum foil with a coating on the surface.

[0140] 3) Drying

[0141] The obtained aluminum foil with the coating on the surface was dried at 120° C. for 15 minutes.

[0142] 4) Sintering treatment

[0143] The dried aluminum foil was then sintered in an argon atmosphere at a heating rate of 10°C / min. After heating to 660°C, the temperature was kept for 20 hours. After the temperature was kept, the foil was naturally cooled to room temperature to obtain an electrode foil with grid-like cracks.

[0144] The electrode foil sintered in Example 3 was sampled and punched into 1 cm×5 cm samples using a punching machine, and then subjected to bending testing using a bending machine.

[0145] Comparative Example 1

[0146] An electrode foil and a method for preparing the same. The steps for preparing the electrode foil are as follows:

[0147] 1) Prepare slurry using aluminum powder as raw material

[0148] Aluminum powder with a particle size D50 of 5 μm was added to a mixed glue formed by polyvinylidene fluoride and carboxymethyl cellulose (the solvent of the mixed glue was phthalate, and the mass ratio of polyvinylidene fluoride to carboxymethyl cellulose in the mixed glue was 1:1), and stirred evenly to prepare a slurry with a slurry viscosity of 2000±100 mPa·s.

[0149] 2) Coating

[0150] The prepared slurry was evenly coated on two opposite surfaces of an aluminum foil with a thickness of 25 μm, and the thickness of the coating on one side was controlled at 65 μm to obtain an aluminum foil with a coating on the surface.

[0151] 3) Drying

[0152] The obtained aluminum foil with the coating on the surface was dried at 120° C. for 15 minutes.

[0153] 4) Sintering treatment

[0154] The dried aluminum foil was sintered in an argon atmosphere at a heating rate of 10°C / min. After heating to 640°C, the temperature was kept for 10 hours. After the temperature was kept, the aluminum foil was naturally cooled to room temperature to prepare an electrode foil.

[0155] The electrode foil sintered in Comparative Example 1 was sampled and punched into 1 cm×5 cm specimens using a punching machine, and then subjected to bending testing using a bending machine.

[0156] Performance Testing

[0157] Bending test: The electrode foils prepared in the examples and comparative examples were sampled and punched into 1 cm × 5 cm samples using an aluminum foil punch. The samples were subjected to a bending test using a bending machine to test the number of transverse and longitudinal bends. The acceptance standard was ≥70 times.

[0158] Table 1 Summary of the bending properties of the electrode foils prepared in the examples and comparative examples

[0159]

[0160]

[0161] Combine Figures 1 to 4 As can be seen from the data in Table 1, compared with Comparative Example 1, Examples 1 to 3 have a significant improvement in the bending performance test. The embodiment of the present invention is to prepare a slurry of aluminum powder, cellulose resin and pure water, and then dry and sinter it after coating, so as to produce cracks, including both transverse cracks and longitudinal cracks, and the transverse cracks and longitudinal cracks are asymmetrically distributed (such as Figure 1 As shown), stress release in multiple directions of the electrode foil is achieved, which increases the continuous toughness of the electrode foil without damaging the electrode foil itself. Therefore, during the cutting, winding, and riveting process of the electrode foil, stress is not concentrated on one point for release, reducing fracture and cracking of the electrode foil. This structural setting improves the bending strength performance, increases the number of horizontal and vertical bending times, reduces fracture and cracking, and thus greatly improves the bending strength of the electrode foil, ensuring the integrity of the electrode foil. In Comparative Example 1, aluminum powder is added to a mixed glue formed by phthalate, polyvinylidene fluoride, and carboxymethyl cellulose to make a slurry, which is then dried and sintered after coating, resulting in transverse cracks but no longitudinal cracks. See Figure 3 and Figure 4As shown in the plan view, the aluminum foil plane has transverse cracks, and the crack distribution is uneven. Such a structure leads to poor bending strength performance, fewer transverse and longitudinal bending times, and during the cutting, winding, and riveting processes, the electrode foil is prone to powder loss or even breakage at the head and tail.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode foil, characterized in that The invention comprises a substrate and a sintered layer composed of an aluminum sintered body on at least one surface of the substrate, wherein the sintered layer on each side has cracks distributed in a grid pattern. The cracks extend from a surface of the sintered layer that is away from the substrate toward a surface of the substrate.

2. The electrode foil according to claim 1, wherein The sintered layer is provided on both opposite sides of the substrate; Based on the substrate, the cracks in the sintered layers on both sides are independently and asymmetrically distributed.

3. The electrode foil according to claim 1 or 2, wherein: Based on a horizontal surface of the sintered layer on one side, the crackle crack comprises a plurality of crack grids. The cracks include a plurality of transverse cracks and a plurality of longitudinal cracks, and the plurality of transverse cracks and the plurality of longitudinal cracks together form the plurality of crack grids; Preferably, each of the transverse cracks independently forms an angle of 0 to 45° with the transverse axis; and / or each of the transverse cracks independently forms a straight line or an irregular curve; Preferably, each of the longitudinal cracks independently forms an angle of 0 to 45° with the longitudinal axis; and / or each of the longitudinal cracks independently forms a straight line or an irregular curve; Preferably, each of the crack grids is independently a complete or incomplete grid; and / or each of the crack grids is independently a regular or irregular grid; Preferably, in the sintered layers located on both sides, the plurality of transverse axis cracks are independently and asymmetrically distributed; Preferably, in the sintered layers located on both sides, the multiple longitudinal cracks are independently and asymmetrically distributed.

4. The electrode foil according to claim 3, wherein In a complete crack grid, based on the transverse axis direction of the horizontal surface, the width of each crack grid is independently 40 μm to 300 μm; and / or, In the complete crack lattice, the width of each crack lattice is independently 40 μm to 200 μm based on the longitudinal axis direction of the horizontal surface.

5. The electrode foil according to claim 1 or 2, wherein: The thickness of the sintered layer on each side is independently 10 μm to 200 μm; Preferably, the thickness of the substrate is 20 μm to 40 μm; Preferably, the substrate is selected from aluminum foil.

6. A method for preparing an electrode foil according to any one of claims 1 to 5, characterized in that: The preparation method comprises: Aluminum powder, a cross-linking agent, and a solvent are mixed to form a slurry; The slurry is coated on at least one side of the surface of the substrate, and is sequentially dried and sintered to obtain the electrode foil.

7. The preparation method according to claim 6, wherein In the slurry, the mass of the solvent is 30% to 70% of the mass of the aluminum powder; and / or the mass of the cross-linking agent is 0.1% to 10% of the mass of the aluminum powder; Preferably, the viscosity of the slurry is 100 mPa·s to 40000 mPa·s.

8. The preparation method according to claim 6, wherein The cross-linking agent includes one or more of silicone resin, organic fluorine polymer, fluoroolefin resin, acrylic resin, and cellulose resin; Preferably, the solvent includes one or more of pure water, starch solution, glycerol, ethylene glycol, terpineol, and ketones; Preferably, the particle size D50 of the aluminum powder is 1 μm to 20 μm.

9. The preparation method according to claim 6, wherein The drying temperature is 50°C to 150°C, and / or the drying time is 1 min to 30 min; Preferably, the sintering temperature is 520° C. to 670° C., and / or the sintering time is 1 h to 50 h, and / or the heating rate of the sintering is 1° C. / min to 20° C. / min; Preferably, the sintering process is carried out under an inert protective atmosphere; Preferably, the inert protective atmosphere is any one of nitrogen atmosphere, helium atmosphere, argon atmosphere and neon atmosphere.

10. An aluminum electrolytic capacitor, characterized in that: The invention relates to an electrode foil comprising the electrode foil according to any one of claims 1 to 5 or an electrode foil prepared by the preparation method according to any one of claims 6 to 9.

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