WO2024181210A1 - 電解コンデンサおよびその製造方法 - Google Patents

電解コンデンサおよびその製造方法 Download PDF

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WO2024181210A1
WO2024181210A1 PCT/JP2024/005842 JP2024005842W WO2024181210A1 WO 2024181210 A1 WO2024181210 A1 WO 2024181210A1 JP 2024005842 W JP2024005842 W JP 2024005842W WO 2024181210 A1 WO2024181210 A1 WO 2024181210A1
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chemical conversion
volts
electrolytic capacitor
vfa
substrate
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French (fr)
Japanese (ja)
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慶明 石丸
義和 平田
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to JP2025503793A priority Critical patent/JPWO2024181210A1/ja
Priority to CN202480014423.0A priority patent/CN120787367A/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-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
    • H01G9/055—Etched foil electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-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
    • H01G9/07—Dielectric layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/15—Solid electrolytic capacitors

Definitions

  • This disclosure relates to an electrolytic capacitor and a method for manufacturing the same.
  • the electrolytic capacitor comprises a capacitor element, which comprises an anode body, a cathode body, and a conductive polymer component interposed between the anode body and the cathode body.
  • Patent Document 1 discloses an electrolytic capacitor equipped with a hydrogen-exhausting membrane, the hydrogen-exhausting membrane including a hydrogen gas permeable layer that selectively allows 99 mol % or more of hydrogen gas to pass when contacted with a mixed gas containing equimolar amounts of hydrogen gas and nitrogen gas, the hydrogen gas permeable layer being a Pd alloy layer containing Au, and the ratio of the average thickness of the oxide film of the anode to the rated voltage of the capacitor (average thickness/rated voltage) being 1.2 to 2.9 (nm/V).
  • the electrolytic capacitor comprises a capacitor element, and the capacitor element comprises an electrode group including an anode body and a cathode body, and a conductive polymer component interposed between the anode body and the cathode body of the electrode group.
  • the anode body comprises a first substrate including a first valve metal, and a first chemical conversion coating covering the surface of the first substrate.
  • a first chemical conversion voltage Vfa applied to the first substrate to form the first chemical conversion coating is 400 volts or more.
  • the ratio of the first chemical conversion voltage Vfa volts to the rated voltage Vw volts of the electrolytic capacitor: Vfa/Vw, is 2.10 or more.
  • the electrolytic capacitor includes a capacitor element
  • the manufacturing method includes a first step of forming an anode body having a first formation coating covering the first substrate and the surface of the first substrate by forming a first formation voltage Vfa volts on a first substrate containing a first valve metal, a second step of preparing a cathode body, a third step of forming an electrode group having the anode body and the cathode body, and a fourth step of forming the capacitor element by interposing a conductive polymer component between the anode body and the cathode body of the electrode group.
  • the first formation voltage Vfa is 400 volts or more.
  • the ratio of the first formation voltage Vfa volts to the rated voltage Vw volts of the electrolytic capacitor: Vfa/Vw is 2.10 or more.
  • This disclosure makes it possible to improve the voltage resistance of electrolytic capacitors.
  • FIG. 1 is a cross-sectional view illustrating a schematic diagram of an electrolytic capacitor according to an embodiment of the present disclosure.
  • FIG. 2 is a perspective view showing a part of the wound body in an expanded state.
  • An electrolytic capacitor according to an embodiment of the present disclosure includes a capacitor element.
  • the capacitor element includes an electrode group including an anode body and a cathode body, and a conductive polymer component interposed between the anode body and the cathode body of the electrode group.
  • the anode body includes a first substrate including a first valve metal, and a first chemical conversion coating covering a surface of the first substrate.
  • a first chemical conversion voltage Vfa applied to the first substrate to form the first chemical conversion coating is 400 volts or more, and a ratio of the first chemical conversion voltage Vfa volts to a rated voltage Vw volts of the electrolytic capacitor: Vfa/Vw is 2.10 or more.
  • the chemical conversion film is not limited to a film formed by a method (hereinafter, the first method) in which a predetermined chemical conversion voltage is applied to the substrate while it is immersed in an acidic aqueous solution (hereinafter, the chemical conversion liquid).
  • the chemical conversion film may be formed by heat treating the substrate while it is immersed in the chemical conversion liquid (hereinafter, the second method).
  • the first method a chemical conversion film having a thickness T according to the chemical conversion voltage is formed.
  • the chemical conversion voltage can be calculated from the thickness T of the chemical conversion film.
  • the chemical conversion voltage required to form the chemical conversion film by the first method can be calculated from the thickness T.
  • the chemical conversion voltage includes the voltage applied to the substrate to form a chemical conversion film of thickness T, and the voltage required to form a chemical conversion film of thickness T.
  • the rated voltage Vw is the maximum voltage specified as a rating, and is the maximum voltage that can be applied between the electrodes of an electrolytic capacitor.
  • the rated voltage Vw may be 200 volts or more or 250 volts or more.
  • the upper limit of the rated voltage Vw is, for example, 400 volts or less.
  • the first chemical voltage Vfa is 400 volts or more, and may be 420 volts or more, 450 volts or more, or 500 volts or more.
  • the first chemical voltage Vfa is, for example, 900 volts or less.
  • Vfa/Vw is 2.10 or more, may be 2.30 or more, or may be 2.50 or more.
  • Vfa/Vw may be 4.00 or less, 3.50 or less, or 3.30 or less.
  • sugar alcohol and/or liquid component solvent or electrolyte
  • Vfa 400 volts or more
  • the first conversion coating tends to become large
  • the ESR increases
  • the capacity decreases.
  • the low ESR and high capacity achieved by attaching sugar alcohol and/or liquid component to the capacitor element can be significantly achieved, for example, when the rated voltage Vw is in the range of 200 volts or more (or 250 volts or more) to 320 volts or less and when Vfa/Vw is in the range of 2.10 to 3.30.
  • the anode body includes a first substrate including a first valve metal, and a first chemical conversion coating covering a surface of the first substrate.
  • the first substrate is in the form of a foil or a sheet.
  • the first valve metal include aluminum, tantalum, niobium, titanium, and the like.
  • the first valve metal may be included in the form of an alloy containing the first valve metal or a compound containing the first valve metal.
  • the first substrate may be, for example, an aluminum foil or an aluminum alloy foil.
  • the thickness of the first substrate may be 15 ⁇ m or more and 300 ⁇ m or less.
  • the surface of the first substrate may be roughened by etching or the like.
  • the anode foil with a roughened surface has a core and a porous portion continuous with the core.
  • the porous portion is provided, for example, on both main surfaces of the first substrate.
  • the ratio of the thickness of the porous portion (thickness per side) to the total thickness of the first substrate may be, for example, 0.1 or more, or 0.2 or more.
  • the ratio of the thickness T of the porous portion (thickness per side) to the total thickness of the first substrate may be, for example, 0.48 or less, or 0.45 or less.
  • the etching process may be performed, for example, by AC etching (AC electrolysis), but is preferably performed by DC etching (DC electrolysis).
  • AC etching AC electrolysis
  • DC electrolysis DC etching
  • porous sections with tunnel-shaped pits are likely to be formed, and during chemical conversion, a chemical conversion coating having a thickness (e.g., 400 nm or more) necessary to ensure voltage resistance is likely to be formed deep into the porous sections.
  • a first substrate having a relatively large thickness is used, and the porous portion has a relatively large thickness.
  • the thickness of the first substrate may be, for example, 50 ⁇ m or more, or may be 100 ⁇ m or more. From the viewpoint of miniaturization of the capacitor, the thickness of the first substrate is, for example, 150 ⁇ m or less.
  • the thickness of the porous portion (thickness per side) may be, for example, 10 ⁇ m or more, or may be 30 ⁇ m or more. From the viewpoint of the strength of the anode body, the thickness of the porous portion (thickness per side) is, for example, 50 ⁇ m or less.
  • the porous portion has a tunnel-shaped pit.
  • the tunnel-shaped pit extends in the thickness direction of the porous portion, that is, extends from the surface side of the porous portion toward the core side. In this case, it is easy to form a thick first chemical conversion coating deep into the pit.
  • conductive polymer components and other components (sugar alcohol, liquid components, etc.) easily penetrate deep into the pit.
  • extending in the thickness direction of the porous portion means that the direction in which the pit extends is parallel to the thickness direction of the porous portion or is inclined at an angle of 80° or less.
  • the angle (acute angle) formed by the direction in which the tunnel-shaped pit extends and the thickness direction of the porous portion is 0° or more and 80° or less, and may be 0° or more and 45° or less, 0° or more and 30° or less, or 0° or more and 15° or less.
  • the modal pore diameter of the tunnel-shaped pits may be, for example, 100 nm or more, 200 nm or more, or 300 nm or more, or 500 nm or more.
  • the upper limit of the modal pore diameter of the tunnel-shaped pits may be 2000 nm or less.
  • the modal pore diameter of the tunnel-shaped pits is the modal pore diameter in the volume-based pore size distribution measured with a mercury porosimeter.
  • the shape of the tunnel-shaped pit can be a columnar shape (e.g., a cylindrical shape, a rectangular prism shape, etc.), a pyramid shape (e.g., a cone shape, a rectangular pyramid shape, etc.), a frustum shape (e.g., a circular truncated cone shape, a rectangular truncated pyramid shape, etc.).
  • the tunnel-shaped pit may be branched in the middle. In the porous portion on one surface side, a part of the tunnel-shaped pit may extend to the core, and may further extend to the porous portion on the other surface side.
  • the porous portion may have spongy pits.
  • the most frequent pore size of the spongy pits may be 50 nm or more and 500 nm or less, or 80 nm or more and 300 nm or less.
  • the most frequent pore size of the pits is the most frequent pore size in the volumetric pore size distribution measured by a gas adsorption method.
  • the first chemical conversion coating functions as a dielectric layer.
  • the first chemical conversion coating is formed by chemically treating the first substrate.
  • the first chemical conversion coating may contain an oxide of a first valve metal (e.g., aluminum oxide).
  • the first chemical conversion coating is formed so as to cover the metal skeleton constituting the porous portion.
  • the thickness of the first chemical conversion coating is preferably 400 nm or more, and more preferably 450 nm or more or 500 nm or more.
  • Vfa is 400 volts or more
  • a first chemical conversion coating having a thickness in the above range can be formed.
  • the thickness of the first chemical conversion coating may be, for example, 1000 nm or less. Note that the thickness of the first chemical conversion coating refers to the thickness of the first chemical conversion coating that covers the outer surface of the porous portion.
  • the end surface of the anode body of the electrolytic capacitor does not need to be formed with a conductive polymer component. However, it is preferable that a first chemical conversion coating is formed on the end surface of the anode body.
  • the cathode body includes, for example, a second substrate including at least a second valve metal.
  • the second substrate is in the form of a foil or a sheet.
  • the second valve metal include aluminum, tantalum, niobium, titanium, and the like.
  • the second valve metal may be included in the form of an alloy including the second valve metal or a compound including the second valve metal.
  • the second substrate may be, for example, an aluminum foil or an aluminum alloy foil.
  • the surface of the second substrate may be roughened by an etching process. The etching process may be performed by the method exemplified for the anode body.
  • a second chemical conversion coating may be formed on the surface of the second base by chemical conversion treatment. That is, the cathode body may include a second base material including a second valve metal and a second chemical conversion coating covering the surface of the second base material.
  • the second chemical conversion voltage Vfc applied to the second substrate to form the second chemical conversion coating is preferably 3 volts or more.
  • the thickness of the second substrate is, for example, 20 ⁇ m or more and 60 ⁇ m or less.
  • the thickness of the second chemical conversion coating is, for example, 1 nm or more, and preferably 3 nm or more.
  • the second chemical conversion voltage Vfc is, for example, 10 volts or less.
  • Vfc/Vfa may be 0.0040 or more, or 0.0050 or more.
  • the cathode body may further include a coating layer (inorganic conductive layer) covering the surface of the second substrate or the second chemical conversion coating.
  • the coating layer may include a metal or a non-metal.
  • the coating layer may include a metal different from the metal constituting the second substrate.
  • the metal may be included in the form of an alloy containing the metal, a compound containing the metal (e.g., nitride, carbide, etc.), etc. Examples of metals included in the coating layer include titanium, nickel, etc. Examples of non-metals included in the coating layer include carbon, etc.
  • the thickness of the coating layer is, for example, 0.03 ⁇ m or more and 3 ⁇ m or less.
  • the electrode group desirably includes a separator interposed between the anode body and the cathode body.
  • a porous sheet can be used as the separator. Examples of the porous sheet include woven fabric, nonwoven fabric, and microporous membrane.
  • the thickness of the separator is not particularly limited and may be in the range of 10 to 300 ⁇ m. Examples of the material of the separator include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamide, polyimide, polyamideimide, polyetherimide, rayon, glass, and the like.
  • a conductive polymer component may be attached to the surface of the separator.
  • the conductive polymer component includes a conductive polymer and may be composed of only a conductive polymer. Alternatively, the conductive polymer component may include a conductive polymer and a dopant.
  • the molecular component is attached to the surface of the electrode group (anode body and cathode body).
  • a layer of the conductive polymer component (solid electrolyte layer) is formed so as to cover at least the anode body (first chemical conversion film).
  • a layer of a conductive polymer component may be formed so as to cover the inner wall surfaces of the pits in the porous portion.
  • Conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyaniline, etc. These may be used alone or in combination of two or more types, or may be copolymers of two or more types of monomers.
  • the weight-average molecular weight of the conductive polymer is not particularly limited, but is, for example, 1,000 to 100,000.
  • polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, etc. refer to polymers having polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, etc. as their basic skeletons, respectively. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, etc. may also include their respective derivatives.
  • polythiophene includes poly(3,4-ethylenedioxythiophene) (PEDOT), etc.
  • the conductive polymer may be doped with a dopant. From the viewpoint of suppressing dedoping from the conductive polymer, it is preferable to use a polymer dopant.
  • polymer dopants include anions of polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, and polyacrylic acid. These may be used alone or in combination of two or more. In addition, these may be homopolymers or copolymers of two or more monomers. Of these, polystyrene sulfonic acid (PSS) is preferable.
  • PSS polystyrene sulfonic acid
  • the weight-average molecular weight of the dopant is not particularly limited, but is preferably, for example, 1,000 to 100,000, in order to facilitate the formation of a homogeneous layer of conductive polymer components (solid electrolyte layer).
  • the conductive polymer component may be poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid.
  • the electrolytic capacitor preferably includes a sugar alcohol.
  • the sugar alcohol is in contact with at least the conductive polymer component. It can also be said that the sugar alcohol is attached to the capacitor element.
  • the hydroxyl group of the sugar alcohol and the hydroxyl group of the anode body surface (first chemical conversion film) are easily bonded, so that the conductive polymer component in contact with the sugar alcohol is easily attached to the anode body (first chemical conversion film), and the ESR can be reduced.
  • the thickness of the first chemical conversion film of the anode body is large, it is advantageous for improving the voltage resistance, but on the other hand, the ESR tends to increase.
  • sugar alcohols include mannitol, sorbitol, xylitol, pentaerythritol, etc.
  • the electrolytic capacitor may include a sugar in contact with the conductive polymer component.
  • sugars include glucose.
  • sugars can reduce the ESR.
  • the electrolytic capacitor preferably includes an electrolyte or a solvent as a liquid component.
  • the liquid component is impregnated (attached) to the capacitor element. From the viewpoint of improving the voltage resistance, the liquid component is preferably only a solvent that does not contain a solute (or an electrolyte with a low concentration of solute).
  • the liquid component is in contact with the conductive polymer component, the anode body (first chemical conversion film), and the cathode body (second chemical conversion film as necessary).
  • the liquid component protects the conductive polymer component. This suppresses the oxidative deterioration of the conductive polymer component and the associated decrease in conductivity.
  • the capacitor element by impregnating the capacitor element with the liquid component, the contact between the conductive polymer component and the chemical conversion film is improved. As a result, the ESR is reduced.
  • the thickness of the first chemical conversion film of the anode body is large, it is advantageous for improving the voltage resistance, but on the other hand, the ESR tends to increase. Therefore, when an anode body with a large thickness of the first chemical conversion film is used, the effect of reducing the ESR by the liquid component is significantly obtained. Furthermore, the liquid component repairs defects in the chemical conversion coating, thereby suppressing an increase in leakage current due to defects in the chemical conversion coating.
  • the electrolyte contains a solvent and a solute dissolved in the solvent.
  • the liquid component may be a component that is liquid at room temperature (25°C) or a component that is liquid at the temperature at which the electrolytic capacitor is used.
  • the solute contains an acid component and a base component.
  • the concentration of the solute is, for example, 3% by mass or more and 35% by mass or less.
  • the concentration of the solute is the sum of the concentration of the acid component and the concentration of the base component.
  • the solvent may be an organic solvent, an ionic liquid, or a protic solvent.
  • solvents include glycol-based solvents such as alkylene glycols (e.g., ethylene glycol, propylene glycol), sulfone-based solvents such as sulfolane, lactone-based solvents such as gamma-butyrolactone, amide-based solvents such as N-methylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone, ester-based solvents such as methyl acetate, carbonate-based solvents such as propylene carbonate, ether-based solvents such as 1,4-dioxane, ketone-based solvents such as methyl ethyl ketone, glycerin, formaldehyde, etc.
  • glycol-based solvents such as alkylene glycols (e.g., ethylene glycol, propylene glycol), sulfone-based solvents such
  • a polymer solvent may be used as the solvent.
  • polymer solvents include polyalkylene glycol, polyglycerin, and derivatives thereof.
  • examples of polymer solvents include polyethylene glycol, polyethylene glycol glyceryl ether, polyethylene glycol diglyceryl ether, polyethylene glycol sorbitol ether, polypropylene glycol, polypropylene glycol glyceryl ether, polypropylene glycol diglyceryl ether, polypropylene glycol sorbitol ether, and polybutylene glycol.
  • polymer solvents further include ethylene glycol-propylene glycol copolymers, ethylene glycol-butylene glycol copolymers, and propylene glycol-butylene glycol copolymers.
  • alkylene glycols e.g. ethylene glycol
  • glycerin e.g. glycerin
  • polyalkylene glycols which are given as examples of polymer solvents
  • the orientation (crystallinity) of the conductive polymer is improved, the conductivity of the conductive polymer component is improved, and the ESR can be reduced.
  • the liquid component may contain an acid component. In this case, dedoping of the dopant is suppressed, and the decrease in the conductivity of the conductive polymer component due to dedoping is suppressed.
  • the acid component may include a compound containing an acidic functional group.
  • the acidic functional group include a carboxy group, a hydroxy group, a sulfo group, a phosphate group, a nitro group, and an oxo group.
  • the acid component may include a carboxylic acid, a phosphoric acid, a sulfonic acid, a boric acid, and/or a salt thereof. More specifically, the acid component includes maleic acid, phthalic acid, benzoic acid, pyromellitic acid, resorcylic acid, borodisalicylic acid, and the like.
  • the compound containing an acidic functional group may be a polycarboxylic acid or a compound having a phenolic hydroxy group.
  • Polycarboxylic acids and monocarboxylic acids can be used as the acid component.
  • Polycarboxylic acids include aliphatic polycarboxylic acids (saturated polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid; unsaturated polycarboxylic acids such as maleic acid, fumaric acid, and itanoic acid), aromatic polycarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid), and alicyclic polycarboxylic acids (cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, etc.).
  • saturated polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic
  • Monocarboxylic acids include aliphatic monocarboxylic acids (1 to 30 carbon atoms) ([saturated monocarboxylic acids, such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid]; [unsaturated monocarboxylic acids, such as acrylic acid, methacrylic acid, oleic acid]), aromatic monocarboxylic acids (such as benzoic acid, cinnamic acid, naphthoic acid), and oxycarboxylic acids (such as salicylic acid, mandelic acid, resorcylic acid).
  • saturated monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, en
  • maleic acid phthalic acid, benzoic acid, pyromellitic acid, and resorcylic acid are preferred because they have high conductivity and are thermally stable.
  • Inorganic acids include carbon compounds, hydrogen compounds, boron compounds, sulfur compounds, nitrogen compounds, and phosphorus compounds.
  • Representative examples of inorganic acids include phosphoric acid, phosphorous acid, hypophosphorous acid, alkyl phosphate esters, boric acid, boric fluoride, tetrafluoroboric acid, hexafluorophosphoric acid, benzenesulfonic acid, and naphthalenesulfonic acid.
  • a composite compound of an organic acid and an inorganic acid can be used as the acid component.
  • examples include borodiglycolic acid, borodisoxalic acid, and borodisalicylic acid.
  • the liquid component may contain a base component in addition to the acid component.
  • Basic components include metal hydroxides such as sodium hydroxide and potassium hydroxide, and nitrogen-containing basic compounds such as aliphatic amines and cyclic amines.
  • metal hydroxides such as sodium hydroxide and potassium hydroxide
  • nitrogen-containing basic compounds such as aliphatic amines and cyclic amines.
  • compounds with alkyl-substituted amidine groups such as imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds)
  • pyrimidine compounds, imidazoline compounds can provide capacitors with high electrical conductivity and excellent impedance performance.
  • Examples of compounds having an alkyl-substituted amidine group include 1,8-diazabicyclo[5,4,0]undecene-7, 1,5-diazabicyclo[4,3,0]nonene-5, 1,2-dimethylimidazolinium, 1,2,4-trimethylimidazoline, 1-methyl-2-ethyl-imidazoline, 1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-heptyl imidazoline, 1-methyl-2-(3'heptyl)imidazoline, 1-methyl-2-dodecyl imidazoline, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1-methylimidazole, 1-methylbenzimidazole, etc.
  • a quaternary salt of a compound having an alkyl-substituted amidine group may be used as the base component.
  • Specific examples include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds) that are quaternized with an alkyl group or arylalkyl group having 1 to 11 carbon atoms.
  • tertiary amines can be used as the base component, and examples of such amines include trialkylamines (trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl n-propylamine, dimethylisopropylamine, methylethyl n-propylamine, methylethylisopropylamine, diethyl n-propylamine, diethylisopropylamine, tri n-propylamine, triisopropylamine, tri n-butylamine, tritert-butylamine, etc.), and phenyl group-containing amines (dimethylphenylamine, methylethylphenylamine, diethylphenylamine, etc.).
  • trialkylamines trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl n-propylamine, dimethylis
  • trialkylamines are preferred because of their high conductivity, and it is more preferable to include at least one selected from the group consisting of trimethylamine, dimethylethylamine, methyldiethylamine, and triethylamine.
  • secondary amines such as dialkylamines, primary amines such as monoalkylamines, and ammonia may be used as the base component.
  • the base component may be included in the liquid component in the form of a salt with the acid component.
  • salts with the acid component include trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono 1,2,3,4-tetramethylimidazolinium phthalate, and mono 1,3-dimethyl-2-ethylimidazolinium phthalate.
  • the capacitor element may be a laminated type capacitor element or a wound type capacitor element.
  • a laminated type capacitor element has a laminated type electrode group formed by laminating an anode body and a cathode body.
  • a wound type capacitor element has a wound type electrode group formed by winding an anode body and a cathode body.
  • a method for manufacturing an electrolytic capacitor according to an embodiment of the present disclosure relates to a method for manufacturing an electrolytic capacitor including a capacitor element, and includes first to fourth steps.
  • First step A first substrate containing a first valve metal is subjected to a chemical conversion treatment at a first chemical conversion voltage Vfa volts to obtain an anode body.
  • the anode body includes a first substrate and a first chemical conversion coating that covers the surface of the first substrate.
  • Second step Prepare the cathode body.
  • Third step Obtain an electrode group comprising an anode body and a cathode body.
  • a conductive polymer component is interposed between the anode and cathode of the electrode group to obtain a capacitor element.
  • the first formation voltage Vfa is 400 volts or more.
  • the ratio of the first formation voltage Vfa volts to the rated voltage Vw volts of the electrolytic capacitor: Vfa/Vw is 2.10 or more.
  • the first substrate that has been subjected to the surface roughening treatment is preferably subjected to a chemical conversion treatment.
  • the manufacturing method preferably includes a step of roughening the surface of the first substrate by a direct current etching method.
  • the second step may include a step of subjecting a second substrate containing a second valve metal to a chemical conversion treatment at a second chemical conversion voltage Vfc volts.
  • a second chemical conversion film is formed on the surface of the first substrate by the chemical conversion treatment. That is, the cathode body includes a second substrate and a second chemical conversion film covering the surface of the second substrate.
  • the second chemical conversion voltage Vfc is 3 volts or more.
  • the ratio of the second chemical conversion voltage Vfc volts to the first chemical conversion voltage Vfa volts: Vfc/Vfa may be 0.0040 or more.
  • the second substrate that has been roughened may be subjected to a chemical conversion treatment.
  • the manufacturing method may include a step of roughening the second substrate.
  • the roughening of the second substrate used in the cathode body may be performed by AC etching or DC etching.
  • a laminated electrode group may be formed by stacking the anode body and the cathode body, or a wound electrode group may be formed by winding the anode body and the cathode body.
  • the electrode group may be formed by interposing a separator between the anode body and the cathode body.
  • a conductive polymer component is attached to the electrode group so that the conductive polymer component is interposed between the anode body and the cathode body.
  • the conductive polymer component may be formed by chemical polymerization or electrolytic polymerization.
  • the fourth step may include a step of preparing a treatment liquid containing a conductive polymer component, and a step of impregnating the electrode group with the treatment liquid and drying the treatment liquid to adhere the conductive polymer component to the electrode group.
  • the treatment liquid containing the conductive polymer component is a solution or dispersion liquid of the conductive polymer component (hereinafter also referred to as a polymer dispersion).
  • the solvent or dispersion medium of the treatment liquid include water, organic solvents, etc.
  • the concentration of the conductive polymer component in the treatment liquid may be, for example, 0.5 to 3 mass %.
  • the viscosity of the treatment liquid may be, for example, 5 mPa ⁇ s to 50 mPa ⁇ s.
  • the impregnation may be performed by immersing the electrode group in the treatment liquid containing the conductive polymer component. The immersion may be performed under atmospheric pressure or under reduced pressure.
  • the electrode group may be immersed in a polymerization solution containing a conductive polymer precursor and an oxidizing agent, and chemical polymerization may be carried out to attach the conductive polymer component to the electrode group.
  • the oxidizing agent may also serve as a dopant, or a dopant may be added separately to the polymerization solution.
  • the production method preferably includes a step A of contacting a sugar alcohol with a conductive polymer component. In the step A, a capacitor element having a sugar alcohol attached thereto is obtained.
  • Step A may include step A-1 of impregnating the electrode group with a sugar alcohol solution and drying to attach the sugar alcohol to the electrode group.
  • the fourth step may be performed after step A-1, and the electrode group to which the sugar alcohol is attached may be impregnated with a treatment liquid containing a conductive polymer component.
  • the drying temperature in step A-1 may be equal to or higher than the melting point of the sugar alcohol.
  • the impregnation may be performed by immersion.
  • the impregnation may be performed under atmospheric pressure or under reduced pressure.
  • Step A may also include a step of impregnating the capacitor element with a sugar alcohol solution and drying.
  • step A may include a step of adding a sugar alcohol to the treatment liquid containing the conductive polymer component of step 4.
  • the treatment liquid containing the conductive polymer component and the sugar alcohol may be used to attach the sugar alcohol together with the conductive polymer component to the electrode group.
  • the manufacturing method preferably includes a step B of impregnating the capacitor element with an electrolytic solution or a solvent as a liquid component.
  • the impregnation in step B may be performed by dropping the liquid component onto the capacitor element.
  • the impregnation in step B may be performed under atmospheric pressure or under reduced pressure.
  • the manufacturing method may include a step of sealing the capacitor element impregnated with the liquid component.
  • the capacitor element and the liquid component may be housed in a bottomed case, a sealing member may be placed at the opening of the bottomed case, a horizontal drawing process may be performed near the open end of the bottomed case, the open end may be crimped to the sealing member to perform curling, and a seat plate may be placed on the curled portion.
  • an electrolytic capacitor may be obtained.
  • an aging process may be performed on the electrolytic capacitor while applying a rated voltage.
  • FIG. 1 is a cross-sectional view showing a schematic diagram of an electrolytic capacitor according to one embodiment of the present disclosure.
  • FIG. 2 is an oblique view showing a portion of the wound body unfolded.
  • the electrolytic capacitor 200 includes a wound body 100 as a capacitor element.
  • the wound body 100 is constructed by winding an anode foil 10 (anode body) and a cathode foil 20 (cathode body) with a separator 30 interposed therebetween.
  • a conductive polymer component is interposed between the anode foil 10 and the cathode foil 20.
  • lead tabs 50A and 50B are connected to the anode foil 10 and the cathode foil 20, respectively, and the wound body 100 is formed by winding the lead tabs 50A and 50B.
  • Lead wires 60A and 60B are connected to the other ends of the lead tabs 50A and 50B, respectively.
  • a stop tape 40 is placed on the outer surface of the cathode foil 20 located at the outermost layer of the wound body 100, and the end of the cathode foil 20 is fixed by the stop tape 40.
  • the wound body 100 may be further subjected to a chemical conversion treatment in order to provide a dielectric layer on the cut surface.
  • the electrolytic capacitor 200 comprises a sealing member 212 that closes the opening of the bottomed case 211, and a seat plate 213 that covers the sealing member 212.
  • the wound body 100 is housed in the bottomed case 211 so that the lead wires 60A, 60B are located on the opening side of the bottomed case 211.
  • the lead wires 60A, 60B are led out from the sealing member 212 and pass through the seat plate 213.
  • the material of the bottomed case 211 can be a metal such as aluminum, stainless steel, copper, iron, brass, or an alloy of these metals.
  • the wound body 100 is sealed in the bottomed case 211 by placing a sealing member 212 at the opening of the bottomed case 211 in which the wound body 100 is stored, crimping the open end of the bottomed case 211 to the sealing member 212 and curling it, and placing a seat plate 213 on the curled portion.
  • the sealing member 212 may be made of any insulating material, and is preferably an elastic material. A material with excellent heat resistance, such as silicone rubber or fluororubber, is preferred.
  • An electrolytic capacitor comprising a capacitor element, the capacitor element comprises: an electrode group including an anode body and a cathode body; and a conductive polymer component interposed between the anode body and the cathode body of the electrode group;
  • the anode body includes a first substrate including a first valve metal and a first chemical conversion coating covering a surface of the first substrate, a first chemical conversion voltage Vfa applied to the first substrate to form the first chemical conversion coating is 400 volts or more;
  • An electrolytic capacitor wherein a ratio Vfa/Vw of the first formation voltage Vfa volts to a rated voltage Vw volts of the electrolytic capacitor is 2.10 or more.
  • the cathode body includes a second substrate including a second valve metal and a second chemical conversion coating covering a surface of the second substrate,
  • a method for manufacturing an electrolytic capacitor having a capacitor element comprising the steps of: a first step of subjecting a first substrate including a first valve action metal to a chemical conversion treatment at a first chemical conversion voltage Vfa volts to obtain an anode body including the first substrate and a first chemical conversion coating covering a surface of the first substrate; A second step of preparing a cathode body; a third step of obtaining an electrode group including the anode body and the cathode body; a fourth step of obtaining the capacitor element by interposing a conductive polymer component between the anode body and the cathode body of the electrode group, the first chemical conversion voltage Vfa is equal to or greater than 400 volts; a ratio Vfa/Vw of the first formation voltage Vfa volts to a rated voltage Vw volts of the electrolytic capacitor is 2.10 or greater.
  • the second step includes a step of subjecting a second base material including a second valve action metal to a chemical conversion treatment at a second chemical conversion voltage Vfc volts to obtain the cathode body including the second base material and a second chemical conversion coating covering a surface of the second base material,
  • Example 1 A wound-type electrolytic capacitor (diameter 10 mm ⁇ length 10 mm) having a rated voltage (Vw) of 320 V and a rated capacitance of 5.6 ⁇ F was prepared in the following manner.
  • the surface of an aluminum foil having a thickness of 100 ⁇ m was roughened by a direct current etching method. This resulted in the formation of a porous portion having tunnel-shaped pits on both sides of the aluminum foil. The most frequent pore size of the pits was within the range of 100 to 300 nm. The thickness of the porous portion per side was 30 ⁇ m.
  • a first chemical conversion coating was formed by performing a chemical conversion treatment on the surface of the roughened aluminum foil (porous portion) at a first chemical conversion voltage Vfa of 672 volts. Thereafter, the anode body was prepared by cutting to a predetermined size. Vfa/Vw was set to 2.10. The thickness of the first chemical conversion coating was 753 nm.
  • the surface of an aluminum foil having a thickness of 50 ⁇ m was roughened by a direct current etching method.
  • a second chemical conversion film was formed on the roughened surface of the aluminum foil by performing a chemical conversion treatment at a second chemical conversion voltage Vfc of 3 volts.
  • Vfc/Vfa was 0.0045.
  • An anode lead tab and a cathode lead tab were connected to the anode body and the cathode body.
  • the anode body and the cathode body were wound with the separator interposed therebetween while winding the lead tabs to form a wound body (wound-type electrode group).
  • An anode lead wire and a cathode lead wire were connected to the ends of the lead tabs protruding from the wound body, respectively.
  • the obtained wound body was again subjected to chemical conversion, and a chemical conversion coating was formed on the cut ends of the anode body.
  • the ends of the outer surface of the wound body were fixed with a winding stop tape.
  • Mannitol (melting point: about 165 to 169° C.) was dissolved in ion-exchanged water to prepare an aqueous mannitol solution (concentration: 10% by mass). The viscosity of the resulting aqueous mannitol solution was measured and found to be 5 mPa ⁇ s or less.
  • the wound body was immersed in the aqueous mannitol solution for 5 minutes at room temperature under atmospheric pressure. The wound body was then removed from the aqueous mannitol solution. The wound body impregnated with the aqueous mannitol solution was then dried at 180° C. for 30 minutes in a drying oven at 1 atm. In this manner, mannitol was attached to the wound body.
  • the wound body with mannitol attached was immersed in a polymer dispersion for 15 minutes at room temperature in a reduced pressure atmosphere (40 kPa), and then the wound body was removed from the polymer dispersion.
  • the wound body was then dried at 150° C. for 30 minutes in a drying oven at 1 atmosphere pressure. In this manner, a conductive polymer component was attached to the wound body to obtain a capacitor element, and the conductive polymer component was brought into contact with mannitol.
  • Electrolyte Impregnation An electrolyte solution was prepared by dissolving triethylamine phthalate (solute) in ethylene glycol (solvent). The electrolyte solution was impregnated into the capacitor element at room temperature under atmospheric pressure.
  • short rate 100 capacitors were produced, and the percentage of the number of capacitors that had a short circuit during aging treatment was calculated as the short circuit rate.
  • the initial ESR and breakdown voltage (BDV) described below were measured for the capacitors other than the capacitor that had a short circuit, and the measured values were averaged to determine the short circuit rate.
  • the initial ESR (m ⁇ ) was measured at a frequency of 100 kHz using an LCR meter for four-terminal measurement.
  • Capacitors A2 and A3 of Examples 2 and 3 were produced and evaluated in the same manner as capacitor A1 of Example 1, except that the rated voltage Vw was set to 300 V or 250 V and Vfa/Vw was set to 2.24 or 2.69.
  • Example 4 Capacitor A4 of Example 4 was fabricated and evaluated in the same manner as capacitor A1 of Example 1, except that the second chemical formation voltage Vfc was set to 4.5 volts.
  • Capacitor A5 of Example 5 was fabricated and evaluated in the same manner as capacitor A1 of Example 1, except that the rated voltage Vw was 200 volts, the first chemical conversion voltage Vfa was 450 volts, and Vfa/Vw was 2.25. The thickness of the first chemical conversion coating of capacitor A5 was 504 nm.
  • Capacitor B1 of Comparative Example 1 was produced and evaluated in the same manner as capacitor A1 of Example 1, except that the rated voltage Vw was set to 330 volts and Vfa/Vw was set to 2.04.
  • Comparative Example 2 The rated voltage Vw was 330 V, and Vfa/Vw was 2.04. The second chemical formation voltage Vfc was 2 V. Except for the above, the capacitor B1 of Comparative Example 1 was produced in the same manner as the capacitor A1 of Example 1 and evaluated.
  • Capacitor B3 of Comparative Example 3 was fabricated and evaluated in the same manner as capacitor A1 of Example 1, except that the rated voltage Vw was 200 volts, the first chemical formation voltage Vfa was 350 volts, and Vfa/Vw was 1.75.
  • Table 1 The evaluation results are shown in Table 1. Note that the ESR in Table 1 is expressed as a relative value with the ESR of B2 being set at 100. Table 1 also shows BDV/Vw. BDV/Vw is an index of voltage resistance, with a higher value indicating higher voltage resistance. A BDV/Vw of 1.2 or higher was evaluated as having excellent voltage resistance.
  • capacitors A1 to A5 the short-circuit rate was small, BDV/Vw was large (1.2 or more), and excellent voltage resistance was obtained.
  • Vfa was 400 volts or more
  • Vfa/Vw was 2.10 or more
  • Vfc was 3 volts or more.
  • the thickness of the first chemical conversion film was large (500 nm or more), but the ESR was reduced due to the effect of the sugar alcohol and electrolyte adhering to the capacitor element.
  • capacitors B1 and B3 Vfa was small relative to Vw, Vfa/Vw was less than 2.10, the short rate increased, and BDV/Vw was small at 1.12 and 0.96, respectively, resulting in reduced voltage resistance.
  • the results for capacitor B3 show that when Vfa is below 400 volts, it is difficult to ensure voltage resistance when Vw is 200 volts or more.
  • Vfa/Vw was less than 2.10. Also, Vfc was small relative to Vw, at less than 3 volts. In capacitor B2, the thickness of the chemical conversion coating was small on both the anode and cathode bodies, and compared to capacitor B1, the short circuit rate further increased, BDV/Vw further decreased to 0.99, and the voltage resistance was significantly reduced.
  • This disclosure can be used for electrolytic capacitors with high rated voltages that require excellent voltage resistance.

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62143414A (ja) * 1985-12-18 1987-06-26 日本電信電話株式会社 長寿命アルミニュウム電解コンデンサの製造方法
JP2006222333A (ja) * 2005-02-14 2006-08-24 Sanyo Electric Co Ltd 固体電解コンデンサ及びその製造方法
WO2009128401A1 (ja) * 2008-04-16 2009-10-22 Ｎｅｃトーキン株式会社 導電性高分子懸濁液、導電性高分子組成物、ならびに固体電解コンデンサおよびその製造方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62143414A (ja) * 1985-12-18 1987-06-26 日本電信電話株式会社 長寿命アルミニュウム電解コンデンサの製造方法
JP2006222333A (ja) * 2005-02-14 2006-08-24 Sanyo Electric Co Ltd 固体電解コンデンサ及びその製造方法
WO2009128401A1 (ja) * 2008-04-16 2009-10-22 Ｎｅｃトーキン株式会社 導電性高分子懸濁液、導電性高分子組成物、ならびに固体電解コンデンサおよびその製造方法

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