CN110648849B - Valve metal porous body coating electrode foil, manufacturing method and electrolytic capacitor - Google Patents
Valve metal porous body coating electrode foil, manufacturing method and electrolytic capacitor Download PDFInfo
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- CN110648849B CN110648849B CN201910918408.XA CN201910918408A CN110648849B CN 110648849 B CN110648849 B CN 110648849B CN 201910918408 A CN201910918408 A CN 201910918408A CN 110648849 B CN110648849 B CN 110648849B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/042—Electrodes or formation of dielectric layers thereon characterised by the material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/042—Electrodes or formation of dielectric layers thereon characterised by the material
- H01G9/045—Electrodes or formation of dielectric layers thereon characterised by the material based on aluminium
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/052—Sintered electrodes
- H01G9/0525—Powder therefor
Abstract
The application provides a valve metal porous body coating electrode foil, combine in the valve metal porous body coating of the at least one side of aluminum foil base member including aluminum foil base member and metallurgy, valve metal porous body coating is piled up the sintering by valve metal powder and is integrative, contains at least one valve metal compound between valve metal powder particle and aluminum foil base member to form electrically conductive connection, valve metal powder contains titanium powder, and the titanium powder volume accounts for 2 ~ 100% of valve metal powder volume. The application promotes metallurgical bonding, forms valve metal porous body coating through amorphous piling up of valve metal powder and through intergranular normal position generation valve metal compound, can obtain high specific volume. The application also claims a manufacturing method of the electrode foil and an electrolytic capacitor based on the electrode foil.
Description
Technical Field
The application relates to the field of electrode foil materials and the technical field of manufacturing, in particular to a valve metal porous body coating electrode foil and an electrolytic capacitor using the same in a manufacturing method thereof.
Background
The electrolytic capacitor is a capacitor having a valve metal surface oxide film as a dielectric layer, and the electrode material is a valve metal. The 'valve metal' described in this patent is a metal having a natural oxide film in the air, and a controllable oxide film can be obtained by anodic oxidation, and the core characteristic of the 'valve metal' as a material of an electrolytic capacitor is that the 'self-healing' characteristic is provided, that is, the defect of the oxide film (natural or anodic oxidation generated) on the surface of the valve metal can be automatically repaired under the conditions of electrolyte (or solid electrolyte) and applied voltage, and no further breakdown is caused. The valve metals currently used for electrolytic capacitors mainly include aluminum, tantalum, niobium and titanium, and each of these valve metals has excellent properties.
The valve metal of the aluminum electrolytic capacitor is aluminum, the electrode foil is aluminum foil, the oxide film on the surface of the aluminum foil is used as a dielectric layer, and the capacitance formula is C ═ epsilon S/(4k pi d), wherein epsilon is the dielectric constant of the dielectric layer (aluminum oxide), S is the specific surface area of the aluminum foil, and d is the thickness of the dielectric layer (aluminum oxide). In order to obtain larger capacity, the electrode aluminum foil is generally subjected to an etching method to increase the specific surface area. However, the capacity of the traditional corrosion method obtained by the material reduction method is limited, the current technical development approaches to the ceiling, and on the other hand, the acid-base pollution is heavy and the environment protection situation is severe.
In order to increase the capacity of the electrode aluminum foil, many practitioners use a method of adding a substance having a higher dielectric constant to increase the value of e, and titanium and its oxides and salts (e.g., titanium oxide) are the main directions of addition.
There are many published patent technologies that increase the specific volume by forming a titanium metal film layer on the surface of an aluminum foil by physical vapor deposition (e.g., evaporation, magnetron sputtering). However, the inventor finds in production practice that the titanium metal film obtained by sputtering is relatively dense, the surface area S is too low, the obtained capacity is limited by the surface area, the specific volume stability of pure titanium metal is poor, and the capacity fading amplitude after hydration is large. To solve the capacity stability of pure titanium coatings, Dongyang optical capacitor Co., Ltd, Dongguan, discloses an improved method for forming a layer of cured silane coupling agent on an electron beam evaporated titanium film, but the method fails to solve the problem of low surface area of evaporated titanium foil
Therefore, how to develop and improve the above-mentioned shortcomings of the prior art is the objective of the related industry, and the present application is proposed by the designer of the present application based on the idea of creation and design with years of experience, through many studies and trials of sample tests, and many modifications and improvements.
Disclosure of Invention
To address one or more of the above-mentioned prior art, the present application provides a valve metal porous body coated electrode foil.
On the one hand, the application provides a valve metal porous body coating electrode foil, combine in the valve metal porous body coating of the at least one side of aluminum foil base member including aluminum foil base member and metallurgy, valve metal porous body coating is piled up and is sintered integratively by valve metal powder, and valve metal powder contains titanium powder at least, and the titanium powder volume accounts for 2 ~ 100% of valve metal powder volume.
The valve metal powder constituting the coating layer is entirely or partially titanium powder. The valve metal powder 3 has an oxide film on the particle surface. The titanium powder is used as all or part of the valve metal powder, the dielectric constant of the titanium oxide film is dozens to dozens of times of that of the aluminum oxide film, the structure which is easy to obtain extremely high specific surface area is the valve metal oxide film with high dielectric constant and the powder coating method, and the capacity which is far higher than that which can be achieved by the prior art can be obtained. The porous body structure formed by stacking the valve metal powder can control the internal stacking porosity through the particle size and the morphology of the powder, and can improve the total surface area through increasing the coating thickness, so that the controllable super-large specific surface area can be comprehensively obtained.
In some embodiments, the valve metal powder other than titanium powder in the valve metal powder is at least one of aluminum powder, niobium powder, and tantalum powder.
In some embodiments, the surface layer of the valve metal powder particles has carbon element, and the carbon element accounts for 0.1-30% of the total weight of the valve metal porous body coating.
In some embodiments, the connecting phase between the valve metal powder particles and the aluminum foil substrate includes a valve metal compound, and the valve metal compound is at least one of a carbide, an oxycarbide, a nitride, and a carbonitride of a valve metal.
In some embodiments, the nitrogen content of the surface layer of the valve metal powder particles is 200 to 10000 ppm by weight.
In some embodiments, the valve metal porous body coating has a thickness of 100 to 10000nm and the median particle diameter of the valve metal powder is 20 to 500 nm.
In some embodiments, the valve metal porous body coating has a thickness of 3 to 300 μm and a median particle diameter of 0.05 to 20 μm.
In some embodiments, the aluminum foil substrate has a thickness of 10 to 100 μm, a purity of 95 wt% or more aluminum, less than 3000 ppm by weight iron, and less than 3000 ppm by weight copper.
In some embodiments, the valve metal powder has an elemental valve metal purity of greater than 98 wt%, an iron content of less than 3000 ppm by weight, and a copper content of less than 3000 ppm by weight.
In some embodiments, the aluminum foil substrate has etched holes in the surface.
In some embodiments, the surface of the valve metal powder in the valve metal porous body coating layer has a formed oxide film obtained by anodic oxidation with application of a voltage.
In some embodiments, the valve metal porous body coating has grooves that open to the outside.
In some embodiments, the surface width of the grooves is 10 to 5000 μm, and the depth of the grooves is 10 to 100% of the thickness of the coating layer of the valve metal porous body.
On the other hand, the present application also requires an electrolytic capacitor having the valve metal porous body-coated electrode foil described above as at least one of the positive electrode and the negative electrode.
In yet another aspect, the present application provides a method of manufacturing a valve metal porous body coated electrode foil, comprising:
forming a valve metal powder accumulation layer on at least one surface of the aluminum foil substrate, wherein the valve metal powder at least contains titanium powder, and the volume of the titanium powder accounts for 2-100% of the volume of the valve metal powder;
a step of manufacturing a valve metal sintered porous body, which is to sinter the aluminum foil substrate with the prefabricated coating in an oxygen-isolated atmosphere; and (5) preparing a product.
In some embodiments, the step of forming the valve metal sintered porous body comprises a step of forming a valve metal sintered porous body by sintering a metal powder.
In some embodiments, the step of forming the valve metal sintered porous body is performed in an oxygen-free atmosphere.
In some embodiments, the step of forming the valve metal sintered porous body is performed in an oxygen-free atmosphere containing a nitrogen-containing gas.
In some embodiments, in the step of manufacturing the valve metal sintered porous body, the sintering is at least one of heat sintering, laser sintering, spark sintering, electromagnetic induction sintering, spark plasma sintering, high pressure sintering, and pulsed light sintering, and the sintering time is from 10 seconds to 100 hours.
In some embodiments, the step of manufacturing the valve metal sintered porous body adopts a heating sintering mode, and the sintering temperature is 300-700 ℃.
In some embodiments, the valve metal powder other than titanium powder in the valve metal powder is at least one of aluminum powder, niobium powder, and tantalum powder.
In some embodiments, the method further comprises a step of forming a chemical oxide film on the surface of the valve metal powder by anodizing with a voltage applied after the step of preparing the valve metal sintered porous body.
In some embodiments, the step of forming the valve metal powder stacked layer includes disposing a pre-coating layer containing valve metal powder and an organic resin on at least one surface of the aluminum foil substrate.
In some embodiments, the organic resin is a mixture of one or more of vinyl chloride vinyl acetate copolymer resin, urea resin, urethane resin, epoxy resin, furan resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, polyamide vinyl acetate resin, polyvinyl butyral, polyurethane resin, acrylic resin, vinyl ester resin, vinyl chloride copolymer resin, acrylonitrile resin, polyvinyl pyrrolidone, polyvinyl alcohol, polyamide wax, polyethylene glycol, polyelectrolyte, vinyl acetate.
In some embodiments, the weight ratio of the organic resin to the valve metal powder is 0.5 to 40%.
In some embodiments, in the step of forming the valve metal powder stack layer, the valve metal powder stack layer is formed by mixing valve metal powder, organic resin and liquid solvent, transferring the mixture to an aluminum foil substrate by coating, printing or die pressing, removing the solvent, and drying and shaping.
In some embodiments, the step of forming the valve metal powder stack is performed without an organic resin.
In some embodiments, the step of forming the valve metal powder stack layer is to form a slurry of valve metal powder and a volatilizable solvent, transfer the slurry to at least one side of the aluminum foil substrate by coating, printing or molding, and volatilize the solvent to obtain a pre-coating layer.
In some embodiments, the step of making the valve metal sintered porous body further comprises the step of making a pre-coating recess, wherein the step of making the coating recess is performed simultaneously with the step of pre-coating or is performed by pressing after the pre-coating. In some embodiments, the valve metal powder has a purity greater than 98 wt%, an iron content of less than 3000 ppm by weight, and a copper content of less than 3000 ppm by weight.
In some embodiments, the valve metal porous body coating has a thickness of 100 to 10000nm, and the valve metal powder used has a median particle diameter of 20 to 500 nm.
In some embodiments, the valve metal porous body coating has a thickness of 3 to 300 μm, and the valve metal powder used has a median particle diameter of 0.05 to 20 μm.
In yet another aspect, the present application claims a valve metal porous body coated electrode foil as a product produced by the above-described method for producing an electrode foil.
Drawings
FIG. 1 is a schematic structural view of one embodiment of a valve metal porous body coated electrode foil provided herein;
FIG. 2 is a schematic structural view of one embodiment of a valve metal porous body coated electrode foil provided herein;
FIG. 3 is a schematic structural view of one embodiment of a valve metal porous body coated electrode foil provided herein;
FIG. 4 is a Ti-C binary phase diagram;
FIG. 5 is a plan sectional view of a Ti-C-N ternary phase diagram at 500 ℃.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the accompanying drawings in combination with specific embodiments.
The application provides a valve metal porous body coating electrode foil, combine in the valve metal porous body coating 2 of the 1 at least one side of aluminium foil base member including aluminium foil base member 1 and metallurgy, valve metal porous body coating 2 is piled up and the sintering is integrative by valve metal powder 3, and valve metal powder 3 contains titanium powder at least, and the titanium powder volume accounts for 2 ~ 100% of 3 volumes of valve metal powder.
The outstanding contribution of the present application is that by the amorphous packing and sintering of the valve metal powder 3 particles, an extremely high specific volume can be obtained by forming the valve metal porous body coating 2. The capacity obtained by the traditional corrosion method of the material reduction method is limited by the thickness and the strength of a base material, the specific volume obtained by the prior art is close to that of a technical ceiling, a porous body coating formed by valve metal powder belongs to the material increase method, the specific volume can control the specific surface area by adjusting the particle size and the coating thickness of powder, and the upper limit of the capacity which can be obtained is far higher than that of the traditional corrosion method of the material reduction method.
A contribution of the present application is that all or part of the valve metal powder constituting the coating is titanium powder. The valve metal powder 3 has an oxide film on the particle surface. The titanium powder is used as all or part of the valve metal powder, the dielectric constant of the titanium oxide film is dozens to dozens of times of that of the aluminum oxide film, the structure which is easy to obtain extremely high specific surface area is the valve metal oxide film with high dielectric constant and the powder coating method, and the capacity which is far higher than that which can be achieved by the prior art can be obtained. The porous body structure formed by stacking the valve metal powder can control the internal stacking porosity through the particle size and the morphology of the powder, and can improve the total surface area through increasing the coating thickness, so that the controllable super-large specific surface area can be comprehensively obtained.
The oxide film provided on the surface of the valve metal powder 3 particles may be formed by natural oxidation. As a further contribution of the present application, the present application provides a valve metal porous body coated electrode foil in which the surface of the valve metal powder 3 in the valve metal porous body coating 4 has a chemical conversion oxide film obtained by anodic oxidation by applying a voltage.
In summary, using a coating containing titanium powder, the high specific surface area obtainable by the powder coating and the high dielectric parameter of the titanium oxide film are combined, and the high dielectric constant ε and the high specific surface area combine to obtain an extremely high specific volume according to the capacitance formula of C ═ ε S/(4k ∈ d).
In another aspect, the present application also provides a method for manufacturing a valve metal porous body coated electrode foil, comprising:
forming a valve metal powder accumulation layer on at least one surface of the aluminum foil substrate 1, wherein the valve metal powder at least contains titanium powder, and the volume of the titanium powder accounts for 2-100% of the volume of the valve metal powder;
a step of manufacturing a valve metal sintered porous body, which is to sinter the aluminum foil substrate 1 with the prefabricated coating in an oxygen-isolated atmosphere; and (5) preparing a product.
After the product is prepared, the valve metal porous body coating electrode foil provided by the application can be naturally oxidized in the air to form a natural oxidation film;
as an optimized aspect of the oxide film on the surface of the particles of the valve metal powder 3, the manufacturing method claimed in the present application further includes a step of forming a chemical oxide film on the surface of the valve metal powder 3 by anodizing with a voltage applied after the step of preparing the sintered porous valve metal body.
In a further embodiment of the present invention, the valve metal porous body coating electrode foil is further provided, wherein the connection phase between the valve metal powder 3 particles and the aluminum foil substrate 1 comprises a valve metal compound 4, and the valve metal compound is at least one of a carbide, an oxycarbide, a nitride and a carbonitride of a valve metal.
A further contribution of the present application is to provide at least one of the in-situ generated carbides, oxycarbides, nitrides, carbonitrides of the valve metal as a reinforcing metallurgical bonding structure.
The skilled person will know from the numerous teachings of the prior art that the sintering temperature of titanium powder is high in the conventional technology, and the difficulty of forming metallurgical bonding sintered body and titanium carbide, oxycarbide and carbonitride without melting the aluminum foil substrate is high. However, the applicant knows that the Ti-C binary phase diagram is shown in FIG. 4, the C-N-Ti ternary phase diagram is shown in a sectional view at 500 ℃ in FIG. 5, and the Ti carbide has a certain yield at 227 ℃, and the titanium nitride and carbonitride can be generated at 500 ℃; it can be seen that the temperature range claimed by the applicant can generate titanium carbide, nitride and carbonitride in a thermodynamic principle, and the difficulty in generating the titanium carbide, nitride and carbonitride in the prior art is that the generation efficiency of the titanium carbide, nitride and carbonitride is extremely low and basically negligible in kinetics at the temperature of below 1000 ℃, and the titanium carbide, nitride and carbonitride can not be generated in an effective using amount. Based on the knowledge of various reaction mechanisms and product requirements through years of research, the applicant can actually generate the compound (at least one) of titanium (valve metal) as a connecting phase for promoting and strengthening the metallurgical bonding between valve metal powder and between the valve metal powder and the aluminum foil matrix through a proper process under the condition of not melting the aluminum foil matrix, and the compound is a prominent contribution of the applicant to the technical development.
The valve metal powder needs to form a conductive communicating body with the aluminum foil substrate through a certain path in order to play the specific surface area of the valve metal powder to obtain capacity, particularly, a natural oxide film with poor conductivity exists on the surface of the valve metal powder, and if the valve metal powder cannot be connected to the aluminum foil substrate by breaking through the non-conductive oxide film on the surface of the valve metal powder, the valve metal powder is a conductive 'isolated island' and has no effect on increasing the specific volume. The prior art is hindered by how to make valve metal powder form conductive connection, and sintering to form a metallurgical bonding sintered body is the most effective method, and the melting point and the stability of various valve metal natural oxide films are significantly higher than those of valve metal simple substances, such as aluminum and titanium, so that sintering is difficult. At least one of the carbide, oxycarbide, nitride and carbonitride of the valve metal generated in situ effectively breaks through an oxide film on the surface of the valve metal, further promotes the formation of further sintering fusion and conductive connection between the valve metal powder and the matrix, and enhances the mechanical connection strength between the powder and the matrix, and the method is a feasible way after the inventors have conducted diligent research and verification.
In the step of manufacturing the valve metal sintered porous body, the sintering mode may be one of heating sintering, laser sintering, electric spark sintering, electromagnetic induction sintering, spark plasma sintering, high pressure sintering, and pulsed light sintering.
The technical scheme of a heating sintering mode is adopted in the step of sintering the porous body by using the valve metal, the sintering temperature is 300-700 ℃, the heating sintering time is different from 10 seconds to 100 hours, the reaction rates at different temperatures are greatly different, the temperature is increased, and the time required by sintering is obviously reduced. The sintering time of other modes is also different, the time range is wide under the influence of the sintering mode and the sintering condition, the time span can be from 0.1 second to 100 hours, particularly, the sintering of laser, electric spark and discharge plasma can be completed within 0.1 second under the condition of the parameter with larger energy, and the longest time is 100 hours under the condition with lower energy.
What is needed to be achieved by the skilled in the art with creative efforts is that the valve metal compound is not directly added, but is generated in situ in the valve metal porous body coating 2 in a plurality of ways in the sintering process, and can break through the natural oxide film on the surface of the valve metal powder to promote the metallurgical bonding between the valve metal powder and the aluminum foil substrate, so as to form the effective conductive connection. This is different from the scheme adopted by Duyunto-sunshine foil forming company in the patent ZL201710086763.6 preparation method of carbon-coated foil for solid aluminum electrolytic capacitor (called "Dongyuo-sunshine carbon-coated foil patent" for short), in which the Dongyuo-sunshine carbon-coated foil patent adopts the steps of coating nano titanium powder slurry on the surface of aluminum foil after anodic oxidation and carbonization, and then carrying out high-temperature carbonization. Wherein the anodic oxidation (formation) and the carbonization can be repeatedly and alternately carried out for a plurality of times. The anodic oxidation can form a thickened and compact artificially-formed alumina film on the aluminum foil, the oxide film is a dielectric substance and has a dielectric constant which is obviously larger than that of a natural oxide film, the carbonization is to carbonize the anodic oxidation bath solution (containing organic components) to form carbon wires, namely, the nano titanium powder slurry is formed on the alumina film and the carbonized carbon wire layer, and the carbon wires are a connecting phase for fixing nano titanium powder. The structure of the formed carbon-coated electrode foil is 'aluminum foil layer/aluminized oxide film layer/carbon wire layer/nano titanium powder layer (/ carbon wire layer)', and the carbon-coated electrode foil is a layered composite structure. In the invention, the thickened anodic oxide film formed on the surface of the aluminum foil substrate in the anodic oxidation and high-temperature treatment is a non-conductive dielectric layer, and the nano titanium powder and the aluminum foil substrate are separated by the high-dielectric oxide film layer and cannot form conductive communication. In the present invention, although there is a step of forming an oxide film on the surface of the valve metal powder 3, the step does not affect the formation of the conductive connection during the sintering process after the sintering is completed.
A further important contribution of the valve metal porous body coated electrode foil claimed in the present application is therefore that the valve metal compounds, the carbides, oxycarbides, nitrides, carbonitrides of the valve metal, are generated in situ between the valve metal powder 3 particles and the aluminium foil substrate 1, the presence of at least one of the above mentioned compounds promoting, enhancing the metallurgical bonding.
The surface layer of the valve metal powder 3 particles of the present application has carbon element, and the proportion of the carbon element in the total weight of the valve metal porous body coating 2 is 0.1-30%.
The surface layer of the valve metal powder 3 particles has carbon elements, which include both the carbide, oxycarbide, carbonitride of the valve metal in the valve metal compound and elemental carbon. These carbon elements are located on the surface of the valve metal powder 3 particles inside the valve metal porous body coating 2, and are uniformly distributed. Therefore, yet another important contribution of the valve metal porous body coating electrode foil claimed in the present application is a deep uniform composite structure of the valve metal porous body coating and carbon uniformly distributed on the inner surface thereof (valve metal powder 3 surface).
The carbon filament is obviously different from the carbon filament in a layered manner disclosed by the Dongyang coated carbon foil patent, and even if the titanium powder layer and the carbon filament in the Dongyang coated carbon foil patent are diffused and permeated, the carbon filament has the characteristic of obvious non-uniform distribution.
The present application also claims a method for producing a valve metal porous body-coated electrode foil, and a method for producing a valve metal porous body-coated electrode foil having at least the following two types of sources of carbon elements on the surface of valve metal powder 3 particles.
One is that the atmosphere for isolating oxygen gas contains carbon-containing gas in the step of manufacturing the valve metal sintered porous body.
Specifically, in the step of manufacturing the valve metal sintered porous body, hydrocarbon substances are isolated from the oxygen atmosphere.
Another method for supplying a carbon source is a step of forming a valve metal powder deposit layer by disposing a pre-coating layer containing valve metal powder and an organic resin on at least one surface of the aluminum foil substrate 1.
The proposal of adopting organic resin is different from the Dongyang coated carbon foil patent which directly forms a nano titanium powder coating on the carbon wire formed by carbonization without using adhesives. After the step of sintering the valve metal porous body coating, the organic resin forms pyrolytic carbon on the surface of the valve metal powder 3 particles, and is further uniformly distributed inside the valve metal porous body coating.
The organic resin is one or more of vinyl chloride-vinyl acetate copolymer resin, urea resin, urethane resin, epoxy resin, furan resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, polyamide-vinyl acetate resin, polyvinyl butyral, polyurethane resin, acrylic resin, vinyl ester resin, vinyl chloride copolymer resin, acrylonitrile resin, polyvinylpyrrolidone, polyvinyl alcohol, polyamide wax, polyethylene glycol, polyelectrolyte and vinyl acetate.
Preferably, the weight ratio of the organic resin to the valve metal powder 3 is 0.5 to 40%.
Specifically, in the step of manufacturing the valve metal powder deposition layer, the method for forming the pre-coating is to mix the valve metal powder 3, the organic resin and the liquid solvent, transfer the mixture to the aluminum foil substrate 1 by coating, printing or die pressing, remove the solvent, and dry and shape the mixture.
The two carbon sources may be used either singly or as combined.
Another important contribution of the method for manufacturing an electrode foil claimed in the present application is to provide a solution in which the pre-coating layer does not contain an organic resin in the step of fabricating the valve metal powder stack layer.
Specifically, the step of manufacturing the valve metal powder accumulation layer is to prepare valve metal powder and a volatilizable solvent into slurry, transfer the slurry to at least one surface of the aluminum foil substrate 1 in a coating, printing or die pressing mode, volatilize the solvent, and obtain a prefabricated coating.
In the technical scheme of the prefabricated coating without organic resin, carbon-containing gas is required to be contained in the oxygen-isolated atmosphere in the step of sintering the porous valve metal body, the carbon-containing gas is used as a carbon source to form a valve metal carbon-containing compound, and further, a carbon simple substance is formed on the surface of valve metal powder.
In addition, the nitrogen content of the surface layer of the valve metal powder 3 particle of the valve metal porous body coating electrode foil claimed in the present application is 200 to 10000 ppm by weight.
The presence of a suitable amount of nitrogen on the surface of the valve metal powder 3 particles, with or without carbon, facilitates the formation of nitrogen compounds or carbonitrides of the valve metal which can act as metallurgically bonded joint phases.
The application claims a method for manufacturing valve metal porous body coating electrode foil, wherein the step of manufacturing the valve metal sintered porous body is isolated from the oxygen atmosphere containing nitrogen-containing gas. Further providing a nitrogen atmosphere. The formation of valve metal nitrides and carbonitrides as metallurgical bonding phases between the valve metal powders can be promoted.
In the valve metal porous body coating electrode foil and the manufacturing method thereof, the thickness of the valve metal porous body coating 2 is 100-10000 nm, and the median particle size of the valve metal powder 3 is 20-500 nm.
In addition, in the valve metal porous body coating electrode foil and the manufacturing method thereof provided by the application, the thickness of the valve metal porous body coating 2 is 3-300 μm, and the median particle size of the valve metal powder 3 is 0.05-20 μm.
Hereinafter, examples of the present invention are provided.
Examples 1 to 10 were prepared by mixing and dispersing valve metal powder and absolute ethanol to prepare a slurry, coating both surfaces of an aluminum foil with the slurry by means of a comma blade transfer coater (examples 1 to 5) and a gravure printer (examples 6 to 10), respectively, drying the slurry to obtain an aluminum foil having a valve metal powder deposition layer, sintering the aluminum foil at 620 ℃ for 40 hours by passing a methane-nitrogen mixed gas, cooling the sintered aluminum foil, and taking out the sintered aluminum foil to obtain a valve metal porous body coating. Examples 1 to 5 were further subjected to anodic oxidation (pressure chemical conversion) treatment at 380V in a boric acid-based chemical solution. The iron content of the valve metal powder 3 used in examples 1 to 10 was 300 ppm by weight, the copper content was 260 ppm by weight, the purity of the aluminum foil was 99.4%, the iron content of the aluminum foil was 500 ppm by weight, the copper content was 400 ppm by weight, the valve metal powder composition, parameters, aluminum foil and coating thickness parameters, and the parameters and performance tests of the valve metal porous body-coated electrode foil produced are shown in table 1.
The electrode foil parameter testing method in the embodiment refers to the electrode foil technical standard (standard number SJ/T11140-:
ratio of static electricityCapacity test method a: the method is used for testing the electrostatic specific volume of a sintered body (an original state after sintering and no anode oxide film), and by referring to a cathode foil capacitance measuring method in an electrode foil technical standard appendix B, an electrostatic capacitance measuring instrument is used, the measuring voltage is below 0.5Vrms, the measuring frequency is 120Hz +/-5 Hz, an ammonium adipate solution (1000 ml of pure water + 150g of ammonium adipate (capacitance level); resistivity of a test solution is used)
The effective test area of the test sample is 5cm2, and the test positive electrode and the test negative electrode are both test samples.
Electrostatic specific volume test method B: the method is used for testing the electrostatic specific volume of the electrode foil with the anodic oxide film, and according to the method for measuring the capacitance of the anodic foil in appendix B of the technical standard of the electrode foil, an electrostatic capacitance measuring instrument is used for measuring the applied bias voltage of 1.5V to 2.0V and the measuring frequency of 120Hz +/-5 Hz, an ammonium pentaborate solution (1000 ml of pure water and 80g of ammonium pentaborate; the resistivity (70 ℃ +/-2 ℃) is 30 omega, cm +/-5 omega, cm and the pH value is used as a test solution
The effective test area of the test sample is 5cm2, the positive electrode is the sample during the test, and the negative electrode is a corrosion aluminum foil with specific volume 40000 mu F/cm 2.
Method A for testing the withstand voltage value of the oxide film: according to the test method for testing the withstand voltage in the annex A of the technical standard of the electrode foil, a TV-1CH type intelligent TV tester is used for testing, and a boric acid solution (1000 ml of pure water and 70g of boric acid (capacitance level)) is used as a test solution, and the resistivity (70 +/-2 ℃) is 7500 omega cm +/-300 omega cm;
the measuring current is 2mA +/-0.1 mA, and the temperature of the measuring liquid is 85 +/-2 ℃. The effective test area of the test sample is 5cm2, the anode is the sample during the test, and the cathode is a metal tank for containing the determination liquid. In the test, the time from the start of energization until the voltage rises to 90% of the rated withstand voltage value was recorded as a voltage rising time (AT), and the voltage reached after the start (180 ± 10) S of AT was recorded as a test withstand voltage value (TV).
Oxide film withstand voltage value test method B: reference electrode foil technical labelThe test method for testing withstand voltage in quasi-appendix A is to use TV-1CH type intelligent TV tester to measure, the test solution uses ammonium adipate solution (1000 ml pure water + 150g ammonium adipate (capacitance level); resistivity
The measuring current is 1mA +/-0.1 mA, and the temperature of the measuring liquid is 85 +/-2 ℃. The effective test area of the test sample is 5cm2, the anode is the sample during the test, and the cathode is a metal tank for containing the determination liquid. In the test, the time from the start of energization until the voltage rises to 90% of the rated withstand voltage value was recorded as a voltage rising time (AT), and the voltage reached after the start (180 ± 10) S of AT was recorded as a test withstand voltage value (TV).
Table 1, examples 1 to 10 show the parameters of aluminum foil, porous body, valve metal powder and electrode foil
As shown in table 1, different performances can be obtained by different compositions, different particle sizes of valve metal powders, and different thicknesses of the valve metal porous body coating 2, wherein the larger the diameter of the valve metal powder is, the smaller the specific surface area is, the specific volume obtained per unit thickness is lower than that of the valve metal powder with a small particle size, a thicker porous body needs to be formed by stacking to obtain a higher specific volume, but the stacking gap between the powders with a large particle size is larger than that of the valve metal powder with a small particle size, and the porous body coating is suitable for a solid polymer electrolyte capacitor, and is particularly suitable for being used as an anode foil of an electrolytic capacitor with a higher rated voltage after forming an oxide film with a high withstand voltage value. As is clear from comparison of the specific capacitance after forming the 375V withstand voltage oxide film with that of the sintered body (natural oxide film) in examples 1 to 5, the thicker the valve metal powder is, the higher the remaining ratio of the capacity after forming the 375V withstand voltage oxide film to the capacity of the sintered body is. However, since the specific surface area is limited when the particle diameter is too large, the particle diameter of the valve metal powder is selected to have an appropriate size in consideration of the pressure resistance of the oxide film to be formed and the desired capacity. The valve metal powder with small particle size has large specific surface area, can obtain extremely high specific volume under the condition of thinner valve metal porous body coating 2 thickness, and is particularly suitable for being used as cathode foil of an electrolytic capacitor. Under the condition of the same other parameters, the high-dielectric-constant valve metals such as Ti, Ta and Nb are beneficial to improving the dielectric constant of the oxide film of the electrode foil and obtaining higher specific volume, but the metal materials are expensive and difficult to process, and the electrode foil with the highest cost performance can be obtained by compounding the metal materials with Al which is low in price, easy to process and higher in pressure resistance value. The compounding of various valve metals can improve the defect of insufficient stability of pure titanium metal, and alloy phases and carbon-containing compounds of composite valve metals can be formed among various valve metals to promote metallurgical bonding.
The application claims the valve metal porous body coating electrode foil, the surface layer of the valve metal powder 3 particles has carbon element, and the proportion of the carbon element in the total weight of the valve metal porous body coating (2) is 0.1-30%.
Examples 11 to 16 valve metal powders, solvents, and organic resins (see table 2) were mixed and dispersed to prepare slurries, the slurries were applied to both sides of an aluminum foil by a slit die coater (examples 11 to 13) and a micro gravure coater (examples 14 to 16), respectively, and dried to obtain an aluminum foil having a valve metal powder deposition layer, the aluminum foil was sintered at 550 ℃ under a 20MHZ electromagnetic induction heating field for 80 hours by introducing nitrogen gas, and the aluminum foil was cooled and taken out to prepare a valve metal porous body.
The iron content of the valve metal powder 3 used in examples 11 to 16 was 300 ppm by weight, the copper content was 260 ppm by weight, the purity of the aluminum foil was 99.4%, the iron content of the aluminum foil was 350 ppm by weight, the copper content was 300 ppm by weight, the valve metal powder composition, parameters, the aluminum foil and the coating thickness parameters, and the parameters and properties of the valve metal porous body-coated electrode foil produced were as shown in Table 3.
Wherein, the carbon content of the valve metal porous body coating 2 is measured by a carbon-sulfur instrument, the weight of the valve metal porous body coating 2 is known by the coating weight of the aluminum powder, and the ratio of the two is the porous carbon content weight ratio. The test methods of the electrostatic specific volume and the capacity retention rate (note) after 1h of hydration are as follows: after the specific volume is tested by adopting the electrostatic specific volume test method A, the sample wafer is cleaned by pure water, the sample wafer is placed into a pure water tank or a beaker with the temperature of more than or equal to 95 ℃ and is kept for 60+1min, the specific volume is tested by the electrostatic specific volume test method A again, and the retention rate after 1h of hydration is (the specific volume after the hydration test/the specific volume before the test) multiplied by 100 percent.
TABLE 2 composition ratio of valve metal powder to organic resin in valve metal powder slurries of examples 11 to 16
TABLE 3 valve metal powder constitution, carbon content and electrode foil Properties of examples 4, 8, 11-16
As shown in table 3, the carbon coating layers uniformly distributed on the surface of the valve metal powder in the valve metal porous body coating electrode foil can effectively improve the hydration specific volume stability of the electrode foil, and a small amount of the carbon coating layers can have an obvious effect, so that the electrostatic capacity of the electrode foil can be reduced when the carbon content is too large, and the comprehensive selection of the carbon content can obtain different specific volumes and hydration retention rates, thereby obtaining the electrode foil with comprehensive properties meeting the performance requirements of different application scenes.
The application claims a valve metal porous body coating electrode foil and a manufacturing method thereof, wherein the thickness of an aluminum foil substrate 1 is 10-100 μm, the purity is more than 95 wt% of aluminum, the iron content is less than 3000 ppm by weight, and the copper content is less than 3000 ppm by weight.
On the basis of the parameters of the aluminum foil substrate 1, the valve metal porous body coating electrode foil and the manufacturing method thereof claimed by the application have the valve metal simple substance purity of more than 98 wt%, the iron content of less than 3000 ppm by weight and the copper content of less than 3000 ppm by weight of the valve metal powder 3.
The main factor determining the core electrical properties of the electrode foil, such as specific volume, leakage current, hydration stability and the like, is the valve metal porous body coating, and the existence of impurities can have adverse effects on the properties, so that the requirement on the purity of valve metal powder is higher than that on an aluminum foil substrate. On the one hand, the economical efficiency is considered, and on the other hand, the aluminum foil matrix mainly determines the mechanical strength, and the higher the purity, the lower the strength, and conversely, the lower the purity, the containing some alloy strengthening elements can have better mechanical strength.
Examples 17 to 25 valve metal powders were mixed with absolute ethyl alcohol and polyvinylpyrrolidone in an amount of 2% by weight of the valve metal powders, and the resulting mixture was dispersed to prepare a slurry, and the slurry was applied to both surfaces of an aluminum foil by means of a comma blade transfer coater (examples 17 to 21) and a gravure printer (examples 22 to 25), followed by drying to obtain an aluminum foil having a valve metal powder deposition layer, sintering the aluminum foil at 640 ℃ for 10 hours by introducing a mixed gas of acetylene, ammonia and argon, and taking out the aluminum foil after cooling to obtain a valve metal porous body. Examples 17 to 21 the valve metal porous body coating layer 2 was 50 μm thick, the valve metal volume ratio was constituted by 95% of Ti and 5% of Al, and the median particle diameter of the valve metal powder 3 was 1 μm, and after sintering to prepare a porous body, further, 21V anodic oxidation (pressure chemical conversion) treatment was performed in an ammonium adipate type chemical solution, and the obtained porous body test oxide film withstand voltage test value was 20V. Examples 21 to 25 the valve metal porous body coating 2 had a thickness of 4 μm, the valve metal powder 3 was Ti of 100%, the median diameter of the valve metal powder 3 was 60nm, and the pressure resistance test value of the surface natural oxide film, which was measured by taking out after sintering, was 1V. The purities and impurity contents of the aluminum foil and the valve metal in examples 17 to 25 are shown in Table 4, and the results of the test of the leak current, tensile strength and bending resistance of the valve metal porous body-coated electrode foil are shown in Table 4
The leakage current test refers to the technical standard of electrode foil, and comprises measuring the voltage withstanding value of oxide film by using the voltage withstanding value test method B, and measuring the resistance of ammonium adipate solution (1000 ml of pure water + 150g of ammonium adipate (capacitance level))
A voltage of 0.9 times the film withstand voltage was applied, and the current value after 10 minutes was measured as the leakage current value.
Tensile strength test methods see electrode foil technical standards: rectangular (150. + -.5) mmX (((10. + -.0.3) mm) sample pieces were die-cut, and any sample piece was placed in a jig of a tensile testing machine, and the tensile strength at break of the test piece was measured at a tensile speed of 10. + -.1 mm/min, and the tensile strength was defined as tensile strength at break (N)/1 (cm).
The bending resistant times test method is the same as the technical standard of the electrode foil: a rectangular sample piece with the thickness of (150 +/-5) mmX (10 +/-0.3) mm is cut through a die, any sample piece is loaded on a clamp of a bending machine, the bending machine is started to carry out bending test at the speed of 6 turns/second under the condition of loading 2.5N +/-0.05N, the bending times of the test piece when the test piece is broken are recorded, and the number of times of bending is counted according to the conditions that the test piece is bent for 1 time at 90 degrees, the test piece is recovered for 2 times, the test piece is bent for 3 times at 90 degrees in the opposite direction, and the test piece is recovered for 4 times.
TABLE 4, EXAMPLES 17-25 aluminum foil and valve metal powder purities, control of impurity levels, and performance results for the resulting electrode foils
The high-performance valve metal porous body coating electrode foil has the advantages that the aluminum foil purity, the iron content and the copper content of the aluminum foil and the valve metal powder influence the performance of the electrode foil on leakage current and mechanical strength. The examples in table 4 show the effect of different aluminum foil purities, aluminum foil and valve metal powder iron and copper contents on leakage current and mechanical strength. The purity of the aluminum foil mainly affects the mechanical strength, the alloy aluminum foil with low purity has high tensile strength and good bending resistance, and the strength of the aluminum foil is reduced after the purity of the aluminum foil is improved. When the valve metal powder has a large particle diameter and the porous body coating layer has a large thickness, the tensile strength is slightly higher than that when the valve metal powder 3 has a small particle diameter and the valve metal porous body coating layer 2 has a small thickness, but the latter is significantly higher than the former in the number of times of bending resistance. The valve metal porous body coating 2 is a brittle body that is hard to deform and bend, the aluminum foil base 1 is a tough body that is extremely flexible and deformable, and the thicker the porous body, the lower the bending strength. The iron and copper contents of the aluminum foil substrate 1 and the valve metal powder affect the leakage current, wherein the iron and copper contents of the valve metal powder constituting the valve metal porous body coating 2 are dominant factors affecting the leakage current, and the influence is greater than the iron and copper contents in the aluminum foil.
According to the high-performance valve metal porous body coating electrode foil, the surface of an aluminum foil substrate 1 is provided with corrosion holes. The corrosion pores on the surface of the aluminum foil substrate 1 may improve the mechanical bonding at the interface between the aluminum foil substrate and the valve metal porous body coating 2.
And in the step of manufacturing the valve metal powder accumulation layer by using the valve metal porous body coating electrode foil manufacturing method, the slurry containing the valve metal powder 3 is wetted and spread on the surface of the aluminum foil substrate 1 to form a high-quality film layer.
The application of the uniform porous body coating consisting of the powder on the electrolytic capacitor electrode foil has two defects, one is poor bending deformation degree and reflects that the brittleness and the bending times resistance on the electrode foil are low, and the second is difficult infiltration of the bottom gap and reflects that the capacity extraction rate on the electrode foil is low.
Another important technical contribution of the protection of the present patent application is: the valve metal porous body-coated electrode foil claimed in the present application further comprises: the valve metal porous body coating 2 has grooves 5 that open to the outside. As shown in fig. 2.
Correspondingly, the method for manufacturing the valve metal porous body coating electrode foil claimed by the application further comprises the step of manufacturing the pre-coating grooves 5 before the step of manufacturing the valve metal sintered porous body. Specifically, the step of forming the coating groove 5 is performed simultaneously in the step of preparing the coating or is performed by pressing after the coating is prepared.
The existence of the groove 5 in the valve metal porous body coating 2 can reduce the infiltration difficulty of the bottom coating and improve the capacity extraction ratio, and on the other hand, the hardened porous bodies can be divided into small blocks to provide space for bending and improve the bending resistance times of the composite electrode foil.
The groove 5 structure can effectively improve the capacity extraction rate and improve the bending resistance. In the embodiment in which the porous body is thicker and the valve metal powder is finer, the improvement effect of the groove 5 is more remarkable, and the improvement ratio of the capacity extraction rate and the number of times of bending resistance is larger.
Examples 26 to 35 valve metal powder (titanium powder 60%: aluminum powder 40%) was mixed and dispersed with polyethylene glycol PEG-200, ethylene glycol, acrylic binder 1% by weight of the valve metal powder to prepare a slurry, and examples 26, 30, 32 were coated on both sides of aluminum foil by comma blade transfer coating-dried to obtain a uniform coatingThe thickness of the coating, in examples 27 to 29, 31, and 33 to 35, the coating with the square grid grooves was printed on both sides of the aluminum foil by gravure printing, the coating with the grooves having different thickness and different array shapes was prepared by gravure coating rollers with different engraving cell parameters (see table 5 for details), and the aluminum foil with the valve metal powder buildup layer was obtained after drying. And (3) introducing acetylene-ammonia-argon mixed gas into the aluminum foil at 550 ℃ for sintering for 60 hours, then sintering for 1min in a nitrogen atmosphere by electric spark, cooling and taking out to obtain the valve metal porous body. The particle size of the valve metal powder, the thickness of the coating layer, the groove array morphology and the properties of the resulting electrode foil used in examples 26 to 35 are shown in Table 5. The sintered electrode foil has electrostatic specific volume measured by the method A, and the capacity extraction rate of the capacitor is obtained by using the electrode foil as cathode foil
The percentage value obtained by dividing the calculated effective specific volume in the liquid lead-type aluminum electrolytic capacitor with the specification of 250V and 100 mu F by the electrostatic specific volume measured by the electrostatic specific volume measuring method A is the capacity extraction rate in the capacitor in the table 5. The bending resistance test method is the same as the test standard of table 4.
TABLE 5 coating, groove array parameters and resulting electrode foil characteristics of examples 26-30
The electrode foil with the groove on the coating in the table 5 has obviously improved bending times and capacity extraction rate. The viscosity of the aqueous solution testing solution (such as ammonium adipate testing solution) used in the specific electrostatic capacity test is extremely low, the aqueous solution testing solution can be soaked into all gaps of the porous body, the electrolyte of the capacitor (the 250V100 muF specification liquid lead type aluminum electrolytic capacitor) is viscous, the impregnation time in the manufacturing process is limited, and the impregnation effect on the porous body is greatly influenced by the structure of the porous body. The electrode foils of the examples without the grooves had low capacity extraction rates, and the comparison of examples 26 and 30 shows that the valve metal powder was about fine, the porous body coating was thicker, the effect of permeation of the electrolytic solution was inferior, the capacity extraction rate was lower, and the number of times of bending resistance was also lower. The embodiment with grooves in the coating has obviously improved capacity extraction rate and bending resistance times compared with the embodiment without grooves, and the valve metal powder is about thin, and the improved amplitude is about large under the condition that the porous body coating is thicker. The relatively thin embodiment of the valve metal coating has a higher coating penetration and bending performance than the thick coating, and the capacity extraction and the number of bending times are inherently higher, and the embodiment with the groove is improved compared with the embodiment without the groove, but the improvement is lower than the thick coating. In summary, the electrode foil of the embodiment having the groove has a significant improvement effect in the electrolyte impregnation effect and the bending resistance times.
The valve metal porous body coating electrode foil and the manufacturing method thereof claimed by the application creatively provide a groove 5 grain structure, and solve the defects of low bending times resistance and difficult infiltration capacity extraction rate of a single powder sintered body coating.
By combining the other improvements and adopting the method, the method has the performance progress of high specific volume, good capacity stability (high hydration resistance), high capacity extraction rate and high bending resistance, and has no environmental protection benefit of acid and alkali pollution.
Preferably, the surface width of the groove 5 is 10 to 5000 μm, and the depth of the groove 5 is 10 to 100% of the thickness of the valve metal porous body coating 2.
The width and depth of the grooves on the coating can be consistent or different, and especially, the grooves with different widths and depths are reasonably compounded to obtain balanced excellent comprehensive performance of capacity, capacity extraction rate and strength.
In the case where the valve metal porous body coatings 2 are provided on both surfaces of the aluminum foil base 1, the grooves 5 may be formed in the valve metal porous body coatings 2 on both surfaces of the aluminum foil base 1 so as to correspond in position and shape, or so as to correspond in shape and shape, or so as to not correspond in position, or so as to not correspond in shape and position, or so as to not correspond in position and so as not to differ in shape.
As shown in fig. 2 and 3, the cross section of the groove 5 is in one or more of a square shape, a trapezoid shape, an arc shape, a triangle shape and an irregular curve shape.
The plane distribution of the grooves 5 is parallel lines, and the central symmetry line of the grooves 5 is parallel to the width direction of the aluminum foil substrate 1.
The plane distribution of the grooves 5 is an intersecting grid array and a non-intersecting grid, and at least one side of the intersecting grid array and the non-intersecting grid is parallel to the width direction of the aluminum foil substrate 1. The valve metal porous body-coated electrode foil claimed in the present application has a winding bending direction in a longitudinal direction when used as a capacitor electrode foil, and has grooves perpendicular to the longitudinal direction (i.e., a width direction) to facilitate the winding bending thereof.
According to the manufacturing method of the electrode foil, the groove 5 can be formed on the prefabricated coating layer directly in the coating process, and the groove can also be formed in a rolling or die pressing mode after the uniform coating layer is formed.
In conclusion, the valve metal porous body coating electrode foil and the manufacturing method thereof have the following characteristics by combining the use;
firstly, the manufacturing mode of the valve metal porous body coating has no acid and alkali pollution.
Secondly, the valve metal porous body coating obtains a larger specific surface area, and titanium powder with the oxide film dielectric constant more than dozens of times higher than that of aluminum is added, so that the valve metal porous body coating can obtain a higher specific volume than a single complete aluminum powder coating of the traditional corrosion method and the published technology of the Toyo aluminum.
In addition, the thickness of the base of the valve metal porous body coating is uniform, the problem of uneven thickness of the residual aluminum core like the corrosion method is solved, and the strength and consistency of the electrode foil are higher than those of the corrosion aluminum foil.
In addition, in the technical scheme with the open-pore grooves 5, the problems of long time for soaking the bottom of a single complete powder coating structure and difficulty in soaking are solved, and the porous body coating is divided by the grooves 5, so that a deformation space can be provided for electrode foil bending, and the defect of poor bending resistance of the electrode foil of the uniform complete powder porous body coating can be overcome.
It should be noted that, in the scope of the present application, not all of the valve metal powder 3 may be titanium powder, and the valve metal powder other than the titanium powder in the valve metal powder 3 may be at least one of aluminum powder, niobium powder, and tantalum powder.
Aluminum, niobium and tantalum are valve metals with large oxide film dielectric constant, and niobium and tantalum have the advantages of low leakage current, good stability, long service life and the like. The aluminum has the advantages of high pressure resistance, strong surge resistance, low price, convenient processing compared with other valve metals, and lower difficulty of sintering to form a metallurgical structure under the condition of not melting an aluminum matrix. The valve metals have the advantages, and the electrode foils with different valve metal powders 3 and proportions can be compounded according to the performance requirements and cost requirements of the use scene. Alloy phases can also be formed between the valve metal powders of different elements to promote sintering and metallurgical bonding.
The present application also claims an electrolytic capacitor having the above valve metal porous body-coated electrode foil as at least one of a positive electrode and a negative electrode.
Up to this point, the present embodiment has been described in detail with reference to the accompanying drawings. From the above description, one skilled in the art should clearly recognize the present application.
It is to be noted that, in the attached drawings or in the description, the implementation modes not shown or described are all the modes known by the ordinary skilled person in the field of technology, and are not described in detail. Furthermore, the above definitions of the various elements and methods are not limited to the specific structures, shapes, or configurations shown in the examples.
It is also noted that the illustrations herein may provide examples of parameters that include particular values, but that these parameters need not be exactly equal to the corresponding values, but may be approximated to the corresponding values within acceptable error tolerances or design constraints. Directional phrases used in the embodiments, such as "upper", "lower", "front", "rear", "left", "right", etc., refer only to the orientation of the drawings and are not intended to limit the scope of the present application. In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.
The above-mentioned embodiments are further described in detail for the purpose of illustrating the invention, and it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not to be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (24)
1. The valve metal porous body coating electrode foil is characterized by comprising an aluminum foil substrate (1) and a valve metal porous body coating (2) metallurgically bonded on at least one surface of the aluminum foil substrate (1), wherein the valve metal porous body coating (2) is stacked and sintered into a whole by valve metal powder (3), the valve metal powder (3) at least comprises titanium powder, and the volume of the titanium powder accounts for 2-100% of the volume of the valve metal powder (3); the valve metal powder (3) except the titanium powder is at least one of niobium powder and tantalum powder; the surfaces of the valve metal powder (3) particles are provided with oxide films; the connecting phase between the valve metal powder (3) particles and the aluminum foil substrate (1) contains a valve metal compound (4), wherein the valve metal compound contains at least one of carbide, nitride and carbonitride of titanium; the surface of the valve metal powder (3) is provided with a carbon simple substance; the surface layer of the valve metal powder (3) particles is provided with valve metal carbon-containing compounds and carbon simple substances; the surface layer of the valve metal powder (3) particles contains valve metal carbon-containing compounds and carbon elements in simple substances, and the proportion of the carbon elements in the valve metal carbon-containing compounds and the carbon elements in the simple substances in the total weight of the valve metal porous body coating (2) is 0.1-30%; the carbon simple substance on the surface of the valve metal powder (3) is formed by sintering in a carbon-containing gas isolated from an oxygen atmosphere; the valve metal carbon-containing compound on the surface of the valve metal powder (3) is formed by a sintering step.
2. A valve metal porous body coated electrode foil according to claim 1, wherein the nitrogen content of the surface layer of the valve metal powder (3) particles is 200 to 10000 ppm by weight.
3. A valve metal porous body coated electrode foil according to claim 1, wherein the thickness of the valve metal porous body coating layer (2) is 100 to 10000nm, and the median particle diameter of the valve metal powder (3) is 20 to 500 nm.
4. A valve metal porous body coated electrode foil according to claim 1, wherein the thickness of the valve metal porous body coating layer (2) is 3 to 300 μm, and the median particle diameter of the valve metal powder (3) is 0.05 to 20 μm.
5. A valve metal porous body coated electrode foil according to claim 1, wherein the aluminum foil substrate (1) has a thickness of 10 to 100 μm, a purity of 95 wt% or more of aluminum, an iron content of less than 3000 ppm by weight, and a copper content of less than 3000 ppm by weight.
6. A valve metal porous body coated electrode foil according to claim 1, wherein the valve metal powder (3) has an elemental purity of valve metal of more than 98 wt%, an iron content of less than 3000 ppm by weight, and a copper content of less than 3000 ppm by weight.
7. A valve metal porous body coated electrode foil according to claim 1, wherein the surface of the aluminum foil substrate (1) has etched holes.
8. A valve metal porous body coated electrode foil according to claim 1, wherein the surface of the valve metal powder (3) in the valve metal porous body coating (2) has a formed oxide film obtained by anodic oxidation by application of a voltage.
9. A valve metal porous body coated electrode foil according to claim 1, wherein the valve metal porous body coating (2) has grooves (5) that are open to the outside.
10. A valve metal porous body coated electrode foil according to claim 9, wherein the surface width of the grooves (5) is 10 to 5000 μm, and the depth of the grooves (5) is 10 to 100% of the thickness of the valve metal porous body coating (2).
11. An electrolytic capacitor, characterized in that: the valve metal porous body-coated electrode foil according to claim 1, wherein the electrode foil is used as at least one of a positive electrode and a negative electrode.
12. A method of manufacturing a valve metal porous body coated electrode foil according to claims 1 to 10, comprising:
forming a prefabricated coating containing valve metal powder (3) on at least one surface of an aluminum foil substrate (1), wherein the valve metal powder at least contains titanium powder, and the volume of the titanium powder is 2-100% of that of the valve metal powder;
a step of manufacturing a valve metal sintered porous body, which is to sinter the aluminum foil substrate (1) with the prefabricated coating in an oxygen-isolated atmosphere; the step of manufacturing the valve metal sintered porous body comprises the step of isolating the atmosphere of oxygen from carbon-containing gas; and (5) preparing a product.
13. The method for manufacturing an electrode foil according to claim 12, wherein the step of manufacturing a sintered porous valve metal body contains a hydrocarbon substance in an atmosphere isolated from oxygen.
14. The method for manufacturing an electrode foil according to claim 12, wherein the step of manufacturing a sintered porous valve metal body further contains a nitrogen-containing gas in an atmosphere isolated from oxygen.
15. The method of manufacturing an electrode foil according to claim 12, wherein the step of manufacturing a sintered porous valve metal body is performed by at least one of heat sintering, laser sintering, spark sintering, electromagnetic induction sintering, spark plasma sintering, high-pressure sintering, and pulsed light sintering.
16. The method for manufacturing an electrode foil according to claim 12, wherein the step of manufacturing a sintered porous valve metal body uses a heat sintering method, and the sintering temperature is 300 to 700 ℃.
17. The method for manufacturing an electrode foil as claimed in claim 12, wherein the valve metal powder (3) other than the titanium powder in the valve metal powder is at least one of aluminum powder, niobium powder and tantalum powder.
18. The method for manufacturing an electrode foil according to claim 12, further comprising a step of anodizing by applying a voltage to form an oxide film on the surface of the valve metal powder (3) after the step of manufacturing the valve metal sintered porous body.
19. The method of manufacturing an electrode foil according to claim 12, wherein the step of forming the valve metal powder stacked layer includes disposing a pre-coat layer containing valve metal powder and an organic resin on at least one surface of the aluminum foil base (1).
20. The method for producing an electrode foil as claimed in claim 19, wherein the weight ratio of the organic resin to the valve metal powder is 0.5 to 40%.
21. The method for manufacturing an electrode foil according to claim 19, wherein the step of forming the valve metal powder deposit layer is performed by mixing the valve metal powder (3), the organic resin, and the liquid solvent, transferring the mixture to the aluminum foil substrate (1) by coating, printing, or molding, removing the solvent, and drying and shaping the mixture.
22. The method of manufacturing an electrode foil according to claim 12, wherein the pre-coat layer does not contain an organic resin in the step of forming the valve metal powder buildup layer.
23. The method for manufacturing an electrode foil as claimed in claim 22, wherein the step of forming the valve metal powder buildup layer is a step of forming a valve metal powder and a volatilizable solvent into a slurry, transferring the slurry to at least one side of the aluminum foil substrate (1) by coating, printing or embossing, and volatilizing the solvent to obtain a pre-coating layer.
24. A method of manufacturing an electrode foil according to claim 12, wherein the step of manufacturing a sintered porous valve metal body further comprises a step of manufacturing a pre-coating recess (5), and the step of manufacturing the coating recess (5) is performed by simultaneous formation in the pre-coating step or by press forming after the pre-coating.
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