WO2021107063A1 - 電解コンデンサ用陰極箔、電解コンデンサ、および、これらの製造方法 - Google Patents

電解コンデンサ用陰極箔、電解コンデンサ、および、これらの製造方法 Download PDF

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WO2021107063A1
WO2021107063A1 PCT/JP2020/044131 JP2020044131W WO2021107063A1 WO 2021107063 A1 WO2021107063 A1 WO 2021107063A1 JP 2020044131 W JP2020044131 W JP 2020044131W WO 2021107063 A1 WO2021107063 A1 WO 2021107063A1
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Prior art keywords
layer
metal
electrolytic capacitor
cathode foil
film
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English (en)
French (fr)
Japanese (ja)
Inventor
吉村　満久
小川　美和
奈津代 笹田
青山　達治
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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 CN202080081081.6A priority Critical patent/CN114730666B/zh
Priority to JP2021561524A priority patent/JPWO2021107063A1/ja
Publication of WO2021107063A1 publication Critical patent/WO2021107063A1/ja
Priority to US17/661,709 priority patent/US12334278B2/en
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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
    • 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
    • H01G9/0029—Processes of 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
    • H01G9/042—Electrodes or formation of dielectric layers thereon characterised by the material
    • H01G9/0425—Electrodes or formation of dielectric layers thereon characterised by the material specially adapted for cathode
    • 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
    • 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
    • H01G9/151—Solid electrolytic capacitors with wound 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
    • H01G9/0029—Processes of manufacture
    • H01G9/0032—Processes of manufacture formation of the dielectric layer
    • 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

  • the present invention relates to a cathode foil for an electrolytic capacitor, an electrolytic capacitor, and a method for manufacturing these.
  • a metal foil containing a valve acting metal is used for the anode body of the electrolytic capacitor. From the viewpoint of increasing the capacitance, at least a part of the main surface of the metal material is subjected to a treatment such as etching to form a porous body. Then, the porous body is subjected to chemical conversion treatment to form a layer of a metal oxide (dielectric) on the surface of the pores or irregularities of the porous body.
  • a roughened metal foil a chemicalized foil obtained by further chemicalizing the roughened metal foil, or a non-valve metal such as titanium is formed on the surface layer of the metal foil. Those are used depending on the application.
  • Patent Document 1 describes a first conductive layer, a mixed layer in which a substance constituting the first conductive layer and carbon are mixed, and substantially carbon on an electrode base material that has not been roughened. Described is a cathode foil for a solid electrolytic capacitor on which a second conductive layer made of the same material is formed.
  • the component concentration of the mixed layer changes from a component structure containing substantially only the substances constituting the first conductive layer to a component structure containing substantially only carbon, from the first conductive layer to the second conductive layer. By changing it toward the layer, a high capacity can be obtained and the characteristics of the electrolytic capacitor such as low ESR can be improved.
  • cathode foil for an electrolytic capacitor that can realize excellent characteristics and a method for manufacturing the same.
  • One aspect of the present invention is a metal porous portion, a metal core portion continuous with the metal porous portion, a first main surface through which pores of the metal porous portion are opened, and the metal porous portion.
  • the present invention relates to a cathode foil for an electrolytic capacitor, which comprises a coating film, and the film is formed to a depth of 10% or more of the thickness of the metal porous portion in the thickness direction of the metal porous portion.
  • Another aspect of the present invention relates to an electrolytic capacitor including the above-mentioned cathode foil for an electrolytic capacitor, an anode body having a dielectric layer formed on its surface, and an electrolyte.
  • Another aspect of the present invention comprises a step of preparing a metal base material having a metal porous portion and a metal core portion continuous with the metal porous portion, and the metal porous portion of the metal base material.
  • the present invention relates to a method for producing a cathode foil for an electrolytic capacitor, which comprises a step of forming a film on the surface of a metal portion to be formed, and the film is formed by an atomic layer deposition method (ALD).
  • ALD atomic layer deposition method
  • the present invention includes a step of obtaining a cathode foil for an electrolytic capacitor by using the method for producing a cathode foil for an electrolytic capacitor, a step of preparing an anode having a dielectric layer on its surface, and the above-mentioned anode.
  • the present invention relates to a method for manufacturing an electrolytic capacitor, which comprises a step of forming a capacitor element using the cathode foil for an electrolytic capacitor.
  • the characteristics of the electrolytic capacitor can be improved.
  • FIG. 5 is a schematic cross-sectional view showing still another example of the cathode foil for an electrolytic capacitor shown in FIG.
  • FIG. 5 is a schematic diagram which developed a part of the winding body included in the electrolytic capacitor.
  • the cathode foil for an electrolytic capacitor according to an embodiment of the present invention includes a metal porous portion, a metal core portion continuous with the metal porous portion, and a first main surface through which pores of the metal porous portion are opened. It has a film that covers the porous metal part. More specifically, the film covers the surface of the metal skeleton that constitutes the porous metal portion.
  • the film may include a conductive first layer containing the first element and / or a second layer which is an oxide film containing the second element.
  • the coating may include both a first layer and a second layer. In that case, the first layer covers at least a part of the second layer.
  • At least one main surface (first main surface) of the cathode foil is roughened, and pores are formed so as to open the first main surface of the cathode foil.
  • the portion of the cathode foil on which the pores are formed on the first main surface side is the metal porous portion, and the inside of the foil in which the pores are not formed is the metal core portion.
  • the main surfaces of the cathode foil (cathode body) and the anode foil (anode body) are the two surfaces of these electrode foils that occupy the largest area macroscopically (visually).
  • the end surface of the cathode foil or the anode foil is a surface existing at an end portion other than the main surface of these electrode foils, and when a large-sized electrode foil is cut, the cut surface is also included.
  • the surface of the electrode foil arranged on the top surface or the bottom surface other than the peripheral surface is the end surface.
  • a natural oxide film is formed on the surface of the cathode foil.
  • the natural oxide film has the function of protecting the metal part of the foil from the electrolyte.
  • the thickness of the natural oxide film may not be sufficient to protect the metal portion from the electrolyte, and the reaction between the metal portion and the electrolyte tends to proceed with the application of a voltage.
  • the reaction between the metal portion and the electrolyte tends to proceed through the thin portion of the natural oxide film.
  • the natural oxide film may not have sufficient water resistance, and when the electrolyte contains water, the foil tends to deteriorate due to the hydration reaction. As a result of these, the ESR tends to be large.
  • the contact area between the electrolyte and the cathode foil becomes large, and it is easy to lower the ESR. Moreover, the capacity on the cathode side can be increased. On the other hand, when the surface area of the foil is large, the reaction with the electrolyte is likely to occur on the surface of the foil, and the foil is likely to be deteriorated.
  • the surface of the cathode foil may be coated with a conductive first layer.
  • the cathode foil substantially functions as a conductor, and a decrease in the capacity of the electrolytic capacitor can be suppressed.
  • the conductive polymer is formed so as to fill the inner inner pores of the porous metal portion.
  • the first layer contains the first element.
  • the first element can be at least one element selected from the group consisting of carbon, nickel, silver, and gold.
  • the electrode foil for an electrolytic capacitor according to the present embodiment may cover the surface of the cathode foil with a second layer which is an oxide film.
  • the capacitance generated on the cathode side can be appropriately increased to suppress a decrease in the capacitance of the electrolytic capacitor as a whole. Further, since the reaction between the metal portion and the electrolyte is suppressed by the second layer, deterioration of the cathode foil is suppressed, and the ESR can be kept low. Further, an electrolytic capacitor having an excellent withstand voltage can be obtained.
  • the second layer contains the second element.
  • the second element can be at least one selected from the group consisting of aluminum, titanium, silicon, tantalum, niobium, hafnium, and zirconium.
  • the thickness of the second layer is set to a desired thickness according to the characteristics of the electrolytic capacitor. From the viewpoint of maintaining the capacity, the thickness of the second layer may be less than or equal to the thickness obtained by forming a metal containing the second element at 4 V. For example, when the second element is aluminum, the thickness of the second layer may be 5 nm or less. On the other hand, from the viewpoint of increasing the withstand voltage, the thickness of the second layer may be thicker than the thickness obtained by forming a metal containing the second element at 4 V.
  • the above description does not necessarily mean that the second layer is formed by chemical conversion treatment. For example, when the second layer is formed by deposition with a thickness that would be obtained if it was formed at 4 V. including.
  • the thickness obtained by forming a metal containing the second element at 4 V is given below.
  • the thickness in the case of silicon corresponds to the thickness of the silicon oxide film that can obtain the same withstand voltage as the aluminum oxide film formed by 4V chemical conversion.
  • the film containing the first layer and / or the second layer is formed to a depth of 10% or more, 20% or more, 30% or more, or 50% or more of the thickness of the porous metal portion in the thickness direction of the porous metal portion. It suffices if it is done.
  • the first layer and / or the second layer can be formed by the ALD (atomic layer deposition) method.
  • the raw material gas precursor material
  • the first layer and / or the second layer also extends to the inner wall of the pores blocked by the metal skeleton of the metal porous portion, which is not exposed from the first main surface in which the pores of the metal porous portion open. Can adhere. Therefore, the first layer and / or the second layer can be formed in a region extending from the first main surface to the deep part of the metal porous portion by using the ALD method.
  • the raw material gas (precursor material) can reach the deep part of the metal porous part away from the outer surface (first main surface) through the pores, but the first main surface.
  • the thinner away from the harder it is for the precursor material to reach.
  • the thickness of the film is thicker toward the side closer to the first main surface (more accurately, the diffusion distance of the raw material gas supplied from the first main surface through the pores), and the first main surface is thicker. It may have a distribution that becomes thinner as the distance from the metal core increases (closer to the metal core).
  • the second layer may be formed by chemical conversion treatment.
  • the chemical conversion state is not stabilized by applying a chemical conversion voltage of 4 V or less, and it is difficult to form a thin chemical conversion film with a uniform film thickness and few defects. Is. In a part of the surface of the metal skeleton of the porous metal portion, a portion where the second layer is not formed or a portion where the thickness of the second layer is thin may occur. As a result, the foil tends to deteriorate due to the reaction with the electrolyte.
  • the thickness of the second layer is uniform, although it may depend on the distance from the first main surface when the thickness of the cathode foil exceeds, for example, 50 ⁇ m.
  • a dense film with few defects can be formed. Therefore, it is possible to easily cover the surface of the metal skeleton with the second layer, which is dense and has few defects, by using the ALD method.
  • a third layer containing at least one of phosphorus and nitrogen may be attached to a region having a depth exceeding 10% of the thickness of the porous metal portion.
  • the third layer may also adhere to a deep portion of the porous metal portion on the metal core portion side where a film containing the first layer and / or the second layer is not formed.
  • the third layer has high solvent resistance to various solvents (particularly water) constituting a liquid component (for example, an electrolytic solution).
  • a liquid component for example, an electrolytic solution
  • the cathode foil when the pH of the liquid component is less than 7 and it is acidic, if the acidic liquid component comes into contact with the metal skeleton portion or the metal core portion of the metal porous portion, the cathode foil is likely to be corroded or deteriorated.
  • the third layer deterioration of the cathode foil can be suppressed.
  • an excellent effect of suppressing deterioration of the cathode body can be obtained even when the pH of the liquid component is less than 5. Further, for example, even when the product is used in a high temperature and high humidity environment at 85 ° C. or higher and a humidity of 85% or higher, the humidity resistance can be enhanced.
  • the liquid component may contain water in the range of 3 to 15% by mass. Even in that case, the hydration reaction is suppressed because the third layer contains phosphorus and / or nitrogen. Therefore, by providing the third layer, deterioration of the cathode foil can be suppressed even when the liquid component contains water.
  • the third layer may be further interposed between the film containing the first layer and / or the second layer and the porous metal portion. Even when a crack or the like occurs in the film, the surface of the porous metal portion is covered with the third layer, so that the metal skeleton portion of the porous metal portion is exposed and contact with the liquid component is suppressed. .. Therefore, deterioration of the cathode foil can be suppressed, and an increase in ESR can be suppressed.
  • the second layer may also contain phosphorus and / or nitrogen.
  • the third layer may form a part or all of the second layer in the film.
  • the third layer is formed by, for example, impregnating the roughened cathode foil with a solution containing a compound containing phosphorus and / or nitrogen (for example, an ammonium phosphate solution) and then drying by heat treatment to obtain pores. It can be attached to the inner side wall. If the chemical conversion solution contains a phosphorus compound and / or a nitrogen compound, the impregnation of the solution may be carried out at the same time as or in parallel with the chemical conversion treatment. The chemical conversion treatment may be performed before the formation of the first layer and / or the second layer, or may be performed after the formation of the first layer and / or the second layer.
  • a solution containing a compound containing phosphorus and / or nitrogen for example, an ammonium phosphate solution
  • FIG. 1 shows a schematic cross-sectional view of the cathode foil according to the embodiment of the present invention.
  • the cathode foil 22 is an integral body of the metal core portion 31 and the metal porous portion 32, and the pores of the metal porous portion 32 are open on the first main surface S1.
  • the metal porous portion 32 has a second main surface S2 at the boundary with the metal core portion 31.
  • the thickness (depth) of the porous metal portion 32 from the first main surface S1 (that is, the distance between the first main surface S1 and the second main surface S2) is indicated by T0.
  • the metal porous portion 32 has pits or pores surrounded by a metal skeleton.
  • a film 33 is formed so as to cover the surface of the metal skeleton of the metal porous portion 32. (See FIGS. 2 to 4).
  • the film 33 may include a first layer 35 and / or a second layer 36.
  • the thickness T1 of the region where the film 33 is formed in the metal porous portion 32 is 10% or more (T1 ⁇ 0.1 T0) of the thickness T0 of the metal porous portion 32.
  • the thickness T1 may be 30% or more of the thickness T0.
  • both the first layer 35 and the second layer 36 can be formed from the first main surface S1 to a depth exceeding 10% or more of the thickness T0 of the metal porous portion 32.
  • at least one of the first layer 35 and the second layer 36 may be formed from the first main surface S1 to a depth exceeding 10% or more of the thickness T0 of the metal porous portion 32. It is preferable that at least the first layer 35 is formed from the first main surface S1 to a depth of more than 10% or more of the thickness T0 of the metal porous portion 32.
  • the thickness of the porous metal portion is not particularly limited, and may be appropriately selected depending on the application of the electrolytic capacitor, the required withstand voltage, and the like.
  • the thickness of the porous metal portion can be, for example, 1 ⁇ m to 60 ⁇ m.
  • the thickness T0 of the porous metal portion may be, for example, 1/10 or more and less than 5/10 of the thickness of the cathode foil.
  • the cathode foil is cut so that a cross section of the metal core portion and the metal porous portion in the thickness direction can be obtained, and an electron micrograph of the cross section is taken to obtain the metal porous portion. It may be obtained as the average value of the thicknesses of any 10 points of.
  • the thickness T1 is determined as the average value of the thicknesses of any 10 points in the region of the porous metal portion where the film 33 having a thickness of 1 nm or more can be confirmed in the electromicrograph.
  • FIG. 2 shows a schematic cross-sectional view of the cathode foil 22 in which the region near the first main surface S1 of the metal porous portion 32 is enlarged.
  • FIG. 2 for the sake of explanation, the pores of the porous metal portion and the first layer 35 and the third layer 37 are emphasized.
  • the scale of each component in the figure does not match the actual scale. This also applies to FIGS. 3 and 4 shown below.
  • the first main surface S1 is roughened, and pores 38 are formed on the roughened main surface.
  • the pores 38 are curved and branched from the first main surface S1 toward the inner part of the metal porous portion 32.
  • the inner wall of the pore 38 is covered with a film 33 containing the first layer 35.
  • the thickness of the first layer 35 is substantially constant, but the closer to the first main surface S1 (more accurately, the shorter the shortest distance to the first main surface S1 via the pores 38). Can be thick.
  • the first layer 35 is also attached to regions (regions X1 and Y1 in FIG. 2) that are not exposed from the first main surface S1 and are blocked from the outside by the metal skeleton of the metal porous portion 32. Such a film 33 is obtained by forming the first layer 35 by the ALD method.
  • a third layer 37 is formed between the film 33 and the metal skeleton of the metal porous portion 32.
  • the third layer 37 contains phosphorus and / or nitrogen and is water resistant.
  • the third layer 37 can also be formed in a deep portion of the metal porous portion 32 in which the film 33 is not formed (a region where the depth from the first main surface S1 exceeds T1).
  • FIG. 3 shows another example of the cathode foil according to the embodiment of the present invention.
  • FIG. 3 is a schematic cross-sectional view of the metal porous portion 32 in the vicinity of the first main surface S1 as in FIG. 2.
  • the pores of the porous metal portion and the second layer 36 and the third layer 37 are emphasized.
  • the scale of each component in the figure does not match the actual scale. This also applies to FIG. 4 shown below.
  • the first main surface S1 is roughened, and pores 38 are formed on the roughened main surface.
  • the inner wall of the pore 38 is covered with a film 33 containing a second layer 36.
  • the thickness of the second layer 36 is substantially constant, but the closer to the first main surface S1 (more accurately, the shorter the shortest distance to the first main surface S1 via the pores 38). Can be thick.
  • the second layer 36 also adheres to regions (regions X2 and Y2 in FIG. 3) that are not exposed from the first main surface S1 and are blocked from the outside by the metal skeleton of the metal porous portion 32.
  • Such a film 33 is obtained by forming the second layer 36 into a film by the ALD method. Similar to FIG. 2, a third layer 37 is formed between the film 33 and the metal skeleton of the metal porous portion 32.
  • the third layer 37 can also be formed in a deep portion of the metal porous portion 32 in which the film 33 is not formed (a region where the depth from the first main surface S1 exceeds T1).
  • FIG. 4 shows still another example of the cathode foil according to the embodiment of the present invention.
  • FIG. 4 is a schematic cross-sectional view of the porous metal portion 32 in the vicinity of the first main surface S1, as in FIGS. 2 and 3.
  • the inner side wall of the pore 38 is covered with a film 33 including the first layer 35 and the second layer 36.
  • the first layer 35 covers the second layer 36.
  • the thickness of the first layer 35 and the second layer 36 is thicker toward the side closer to the first main surface S1 (more accurately, the shorter the shortest distance to the first main surface S1 via the pores 38). It is formed. Further, the first layer 35 and the second layer 36 are also formed in regions (regions X3 and Y3 in FIG. 4) that are not exposed from the first main surface S1 and are blocked from the outside by the metal skeleton of the metal porous portion 32. It is attached. Similar to FIGS. 2 and 3, a third layer 37 is formed between the film 33 and the metal skeleton of the metal porous portion 32. Although not shown, the third layer 37 can also be formed in a deep portion of the metal porous portion 32 in which the film 33 is not formed (a region where the depth from the first main surface S1 exceeds T1).
  • the film thickness of the first layer 35 is, for example, 1 nm to 50 nm, and may be 1 nm to 30 nm.
  • the film thickness of the second layer 36 is, for example, 1 nm to 10 nm.
  • the film thickness of the film 33 (the total film thickness of the first layer and the second layer) is, for example, 2 nm to 60 nm.
  • these film thicknesses are the film thicknesses at arbitrary 10 points in the surface layer region where the depth from the first main surface S1 is 100 nm or less in the electron micrograph of the cross section of the metal porous portion 32 in the thickness direction. It is calculated as the average value of.
  • the film thickness of the third layer 37 is, for example, 2 nm or less, and may be 0.08 nm to 2 nm.
  • the film thickness of the third layer 37 is obtained as an average value of the film thicknesses at any 10 points in the electron micrograph of the cross section of the metal porous portion 32 in the thickness direction.
  • the concentration of phosphorus or nitrogen contained in the third layer is preferably, for example, 0.5 at% or more and 7.0 at% or less, and more preferably 1.0 at% or more and 5.0 at% or less, from the viewpoint of suppressing deterioration of the cathode foil. ..
  • the concentration of phosphorus or nitrogen contained in the third layer is determined by observing a cross section of the cathode foil cut in the thickness direction with a transmission electron microscope (TEM) and using an X-ray microanalyzer (XMA) in a desired region of the cathode foil. ) Is used for composition analysis.
  • the concentration of phosphorus or nitrogen is determined by averaging the measured values at any 10 points.
  • the type of metal constituting the metal core portion and the metal porous portion is not particularly limited, but a metal having a valve action, for example, aluminum, tantalum, niobium, etc. is preferable.
  • the surface of the cathode foil is roughened (formation of the metal porous portion) by etching the metal foil. Further, if necessary, an oxide film (second layer) may be formed on the surface of the cathode foil by chemical conversion treatment of the cathode foil.
  • the pore diameter peak of the pits or pores of the porous metal portion is not particularly limited, but from the viewpoint of increasing the surface area and forming the first layer or the second layer deep into the porous metal portion, for example, from 50 nm to It may be 2000 nm, and may be 100 nm to 300 nm.
  • the pore size peak is, for example, the most frequent pore size of the volume-based pore size distribution measured by a mercury porosimeter.
  • Examples of the conductive material for forming the first layer include amorphous carbon, a metal, a conductive metal compound, and the like, which can be deposited by the ALD method.
  • the metal and the metal compound those that do not easily form a passivation film due to contact with air or the like are preferable.
  • Examples of the metal include silver, gold, titanium, titanium alloy, nickel, nickel alloy and the like.
  • Examples of the metal compound include nitrides and carbides, and nitrides are preferable.
  • Examples of the metal constituting the metal compound include titanium and / or nickel.
  • the first layer may contain one kind of these materials, or may contain two or more kinds of these materials.
  • the first layer is the first main surface. It may be formed in a shallow region near S1.
  • the film forming method of the first layer is not limited to the ALD method, and a vapor phase method such as chemical vapor deposition, vacuum vapor deposition, sputtering, or ion plating may be used.
  • the element other than oxygen (second element) contained in the oxide film constituting the second layer may be the same as or different from the metal element constituting the porous metal portion.
  • the thickness (depth) of the region where the first layer is formed is the thickness (depth) of the region where the second layer is formed in the porous metal portion. ) May be thicker.
  • the electrolytic capacitor according to the present embodiment includes the above-mentioned cathode foil for an electrolytic capacitor, an anode body having a dielectric layer formed on its surface, and an electrolyte.
  • the components other than the cathode foil of the electrolytic capacitor will be described in detail below.
  • a metal foil can be used as the anode body.
  • the type of metal contained in the metal foil is not particularly limited, but one containing a metal having a valve action such as aluminum, tantalum, niobium, and titanium is preferable because the dielectric layer can be easily formed.
  • those containing a second metal as a main component for example, a simple substance of a metal such as aluminum or an alloy such as an aluminum alloy are preferable.
  • the surface of the anode body is roughened, and a dielectric layer is formed on the surface of the roughened metal foil.
  • a separator In an electrolytic capacitor that uses an electrolytic solution as an electrolyte, a separator may be used to separate the anode body and the cathode foil.
  • the material of the separator is, for example, a non-woven fabric or film mainly composed of cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamide, polyimide, polyamideimide, polyetherimide, rayon, glassy substance, etc. Can be used.
  • the electrolyte may include liquid components and / or solid electrolytes. If the electrolyte does not contain a solid electrolyte, the liquid component is an electrolyte. When the electrolyte contains a solid electrolyte, the liquid component may or may not be an electrolytic solution. The liquid component may have an effect of enhancing the repairability of the dielectric layer formed on the surface of the anode on the anode side of the electrolytic capacitor. As the solid electrolyte, a conductive polymer can be used.
  • Conductive polymer As the conductive polymer, polypyrrole, polythiophene, polyaniline and the like are preferable. These may be used alone, in combination of two or more, or in a copolymer of two or more monomers.
  • the weight average molecular weight of the conductive polymer is not particularly limited, but is, for example, 1000 to 100,000.
  • polypyrrole, polythiophene, polyaniline, etc. mean macromolecules having polypyrrole, polythiophene, polyaniline, etc. as their basic skeletons, respectively. Therefore, polypyrrole, polythiophene, polyaniline and the like may also contain their respective derivatives.
  • polythiophene includes poly (3,4-ethylenedioxythiophene) (PEDOT) and the like.
  • Dopants may be added to the conductive polymer. From the viewpoint of suppressing dedoping from the conductive polymer, it is desirable to use a polymer dopant.
  • the polymer dopant include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly (2-acrylamide-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polyacrylic. Examples include anions such as acids. These may be used alone or in combination of two or more. Further, these may be homopolymers or copolymers of two or more kinds of 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 1000 to 100,000, for example, in that a homogeneous solid electrolyte layer can be easily formed.
  • the liquid component may be a non-aqueous solvent or a mixture (that is, an electrolytic solution) of the non-aqueous solvent and an ionic substance (solute, for example, an organic salt) dissolved therein.
  • the non-aqueous solvent may be an organic solvent or an ionic liquid.
  • a high boiling point solvent is preferable.
  • polyhydric alcohols such as ethylene glycol and propylene glycol
  • cyclic sulfones such as sulfolane (SL)
  • lactones such as ⁇ -butyrolactone (GBL)
  • N-methylacetamide N, N-dimethylformamide
  • N- Amides such as methyl-2-pyrrolidone
  • esters such as methyl acetate
  • carbonate compounds such as propylene carbonate (PC)
  • ethers such as 1,4-dioxane
  • ketones such as methylethylketone
  • formaldehyde formaldehyde
  • polymer solvent examples include polyalkylene glycols, derivatives of polyalkylene glycols, compounds in which at least one hydroxyl group of a polyhydric alcohol is replaced with polyalkylene glycol (including derivatives), and the like.
  • polyethylene glycol (PEG) 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, polybutylene glycol, etc.
  • PEG 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, poly
  • the polymer solvent may be, for example, a copolymer of ethylene glycol-propylene glycol, a copolymer of ethylene glycol-butylene glycol, a copolymer of propylene glycol-butylene glycol, or the like.
  • the copolymer may be a random copolymer.
  • the liquid component may contain an acid component and a base component.
  • a polycarboxylic acid and a monocarboxylic acid can be used.
  • the polycarboxylic acid 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, sebatic acid, 1,6).
  • -Decandicarboxylic acid, 5,6-decandicarboxylic acid] ; [unsaturated polycarboxylic acid, such as maleic acid, fumaric acid, icotanic acid]), aromatic polycarboxylic acid (eg, phthalic acid, isophthalic acid, terephthalic acid, tri) Merit acid, pyromellitic acid), alicyclic polycarboxylic acid (for example, cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, etc.) can be mentioned.
  • aromatic polycarboxylic acid eg, phthalic acid, isophthalic acid, terephthalic acid, tri
  • Merit acid eg. pyromellitic acid
  • alicyclic polycarboxylic acid for example, cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, etc.
  • Examples of the monocarboxylic acid include aliphatic monocarboxylic acids (1 to 30 carbon atoms) ([saturated monocarboxylic acids such as formic acid, acetic acid, propionic acid, butylic acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, and capric acid.
  • aromatic monocarboxylic acid eg benzoic acid, silicic acid, Naftoeic acid
  • oxycarboxylic acid eg salicylic acid, mandelic acid, resorcynic acid.
  • maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcinic acid are preferably used because they have high conductivity and are thermally stable.
  • Examples of the inorganic acid include carbon compounds, hydrogen compounds, boron compounds, sulfur compounds, nitrogen compounds, and phosphorus compounds.
  • Typical examples of inorganic acids are phosphoric acid, phosphite, hypophosphite, alkyl phosphate ester, boric acid, boric acid, boric acid tetrafluoride, phosphoric acid hexafluoride, benzenesulfonic acid, naphthalenesulfonic acid. And so on.
  • a composite compound of an organic acid and an inorganic acid can be used as an acid component.
  • borodiglycolic acid, borodioxalic acid, borodisalicylic acid and the like can be mentioned.
  • the basic component is a compound having an alkyl-substituted amidine group, and examples thereof include an imidazole compound, a benzoimidazole compound, and an alicyclic amidine compound (pyrimidine compound, imidazoline compound). Specifically, 1,8-diazabicyclo [5,4,0] undecene-7,1,5-diazabicyclo [4,3,0] nonen-, which can provide a capacitor having high conductivity and excellent impedance performance.
  • a quaternary salt of a compound having an alkyl-substituted amidine group can also be used as a base component, and an imidazole compound, a benzoimidazole compound, or an alicyclic amidine compound quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group can be used.
  • an imidazole compound, a benzoimidazole compound, or an alicyclic amidine compound quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group can be used.
  • tertiary amines can also be used as the base component, and trialkylamines (trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyln-propylamine, dimethylisopropylamine, methylethyln-propylamine, methylethylisopropylamine) can also be used.
  • trialkylamines trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyln-propylamine, dimethylisopropylamine, methylethyln-propylamine, methylethylisopropylamine
  • phenyl group-containing amines (dimethylphenylamine, methylethylphenylamine, diethylphenylamine) Etc.).
  • trialkylamines are preferable in terms of high conductivity, and it is more preferable to contain at least one selected from the group consisting of trimethylamine, dimethylethylamine, methyldiethylamine and triethylamine.
  • a secondary amine such as dialkylamines, a primary amine such as monoalkylamine, or ammonia may be used.
  • the liquid component may contain an acid component, a base component, and / or a salt of the acid component and the base component.
  • the salt may be an inorganic salt or an organic salt.
  • An organic salt is a salt in which at least one of an anion and a cation contains an organic substance. Examples of the organic salt include trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono1,2,3,4-tetramethylimidazolinium phthalate, and mono 1,3-dimethyl-2-phthalate. Ethylimidazolinium or the like may be used.
  • the pH of the liquid component may be less than 7 or 5 or less. By setting the pH of the liquid component in the above range, dedoping of the dopant of the conductive polymer can be suppressed. On the other hand, when the pH of the liquid component is less than 7, the cathode foil tends to deteriorate. In this case, it is preferable to form the above-mentioned third layer on the surface of the metal porous portion of the cathode foil. Since the third layer contains phosphorus and / or nitrogen, deterioration of the cathode foil can be suppressed.
  • FIG. 5 is a schematic cross-sectional view of the electrolytic capacitor according to the present embodiment
  • FIG. 6 is a schematic view of a part of the winding body included in the electrolytic capacitor.
  • the following embodiments do not limit the present invention.
  • the electrolytic capacitor covers, for example, the capacitor element 10, the bottomed case 11 accommodating the capacitor element 10, the sealing member 12 that closes the opening of the bottomed case 11, and the sealing member 12.
  • the capacitor element 10 is housed in an outer case together with a liquid component. The vicinity of the open end of the bottomed case 11 is drawn inward, and the open end is curled so as to be crimped to the sealing member 12.
  • the capacitor element 10 is manufactured, for example, by adhering a conductive polymer to a wound body as shown in FIG.
  • the wound body includes an anode body 21 having a dielectric layer, a cathode body (cathode foil) 22 containing a first metal having a valve action, and a separator 23 interposed between them.
  • the conductive polymer is attached so as to cover at least a part of the surface of the dielectric layer of the anode body 21.
  • the capacitor element 10 further includes a lead tab 15A connected to the anode body 21 and a lead tab 15B connected to the cathode body 22.
  • the anode body 21 and the cathode body 22 are wound around the separator 23.
  • the outermost circumference of the winding body is fixed by the winding stop tape 24.
  • FIG. 6 shows a partially unfolded state before stopping the outermost circumference of the winding body.
  • the anode body 21 includes a metal foil whose surface is roughened so as to have irregularities, and a dielectric layer is formed on the main surface of the metal foil having irregularities.
  • the winding type electrolytic capacitor has been described, but the scope of application of the present invention is not limited to the above, and other electrolytic capacitors, for example, a chip type electrolytic capacitor using a metal sintered body as an anode body. It can also be applied to a laminated electrolytic capacitor that uses a metal plate as an anode.
  • the method for producing a cathode foil for an electrolytic capacitor includes, for example, (i) a step of preparing a metal base material having a metal porous portion and a metal core portion continuous with the metal porous portion, and ( ii) The step of forming a film on the surface of the metal portion constituting the metal porous portion of the metal base material is included.
  • the film is formed by atomic layer deposition (ALD).
  • the production method may further include (iii) a step of adhering at least one of phosphorus and nitrogen to a region having a depth of more than 10% of the thickness of the porous metal portion in the thickness direction of the porous metal portion.
  • An electrolytic capacitor can be manufactured by a method including the step of forming a capacitor element.
  • Step (i) of preparing the metal base material may be, for example, a step of roughening the metal foil.
  • a metal porous portion having a plurality of pits or pores is formed on the surface side of the metal foil.
  • a metal core portion integrated with the metal porous portion is formed on the inner portion of the metal foil.
  • the roughening can be performed by a known method, and for example, the roughening may be performed by etching. Etching can be performed, for example, by direct current etching with a direct current or alternating current etching with an alternating current.
  • the type of metal constituting the metal foil is not particularly limited, but a valve acting metal such as aluminum (Al), tantalum (Ta), niobium (Nb) or an alloy containing a valve acting metal can be used.
  • the thickness of the metal foil is not particularly limited, but is, for example, 15 ⁇ m or more and 100 ⁇ m or less.
  • the step of forming the film (ii) is a step of forming a conductive first layer containing the first element and / or a step of forming a second layer which is an oxide film containing the second element.
  • the first element can be at least one selected from the group consisting of carbon, nickel, silver, and gold.
  • the second element can be at least one selected from the group consisting of aluminum, titanium, silicon, tantalum, niobium, hafnium, and zirconium. Both the first layer and the second layer may be formed. In that case, the formation of the first layer takes place after the formation of the second layer.
  • the first and second layers can be formed, for example, by atomic layer deposition (ALD).
  • ALD atomic layer deposition
  • a dense film with few defects can be formed deep inside the winding pores in the porous metal portion.
  • the first and second layers can also adhere to the inner sidewalls of the pores that are not exposed from the outer surface of the foil (ie, shielded from the outside by the metal skeleton of the porous metal portion).
  • a film containing the first layer and / or the second layer is formed by a vapor phase method such as vacuum deposition or sputtering, the film forms the inner side wall of the pore in a shallow region near the outer surface of the foil. Although it can be formed so as to cover it, it is difficult to form it in a region deep in the metal porous portion that is not exposed from the outer surface of the metal porous portion.
  • the precursor material for forming the film can reach a region distant from the outer surface to some extent through the pores of the porous metal portion.
  • the film thickness of the film formed on the porous metal portion may have a distribution that is thicker on the outer surface side of the foil and becomes thinner as the distance from the outer surface increases.
  • the film thickness (thickness of the first layer and / or the second layer) of the film at an arbitrary position of the porous metal portion depends on the length of the shortest path to the outer surface through the pores of the porous metal portion. However, although it does not necessarily depend on the shortest distance to the outer surface, it is generally formed thicker as the distance from the outer surface of the porous portion is shorter.
  • a raw material gas containing a first element or a second element is supplied to a reaction chamber in which an object is arranged, and a conductive first layer containing the first element is provided on the surface of the object.
  • a second layer which is an oxide film of the second element, can be formed.
  • the self-limiting action works, so that the first element or the second element is deposited on the surface of the object in atomic layer units. Therefore, the thicknesses of the first layer and the second layer can be controlled by the number of cycles including the supply of the raw material gas ⁇ the exhaust (purge) of the raw material gas in one cycle. That is, the thickness of the first layer and / or the second layer can be easily controlled by using the ALD method.
  • the first element or the second element is supplied to the reaction chamber as a precursor gas containing the first element or the second element, respectively.
  • the precursor is, for example, an organometallic compound containing a first element or a second element, which facilitates chemical adsorption of each element to an object.
  • various organometallic compounds conventionally used in the ALD method can be used.
  • the raw material gas containing the second element and the oxidizing agent are alternately supplied to the reaction chamber.
  • the thickness of the second layer is controlled by the number of cycles in which the supply of the raw material gas ⁇ the exhaust of the raw material gas (purge) ⁇ the supply of the oxidant ⁇ the exhaust of the oxidant (purge) is set as one cycle.
  • the oxidizing agent include water, oxygen, ozone and the like.
  • the oxidant may be supplied to the reaction chamber as plasma using the oxidant as a raw material.
  • the ALD method can be performed under a temperature condition of 100 to 400 ° C. That is, the ALD method is excellent in that it can suppress thermal damage to the metal foil.
  • Examples of the C (carbon) -containing precursor that can be used for forming the first layer include alkanes having 5 to 11 carbon atoms such as hexane.
  • Ni-containing precursor examples include bis (cyclopentadiniel) nickel (Ni (C 5 H 5 ) 2 ) and bis (isopropylcyclopentadiniel) nickel (Ni (i-C 3 H 7 C 4).
  • examples thereof include H 5 ) 2 ), bis (ethylcyclopentageniel) nickel (Ni (C 2 H 5 C 4 H 5 ) 2 ), and tetrakis (trifluorophosphine) nickel (Ni (PF 3 ) 4).
  • precursor containing Ag for example, 2,2,6,6-tetramethyl-3,5-Jioneto silver (I) (Ag (C 11 H 19 O 2)
  • precursor containing Au examples include dimethyl (acetylacetonate) gold (III) (Au ((CH 3 ) 2 ) C 5 H 7 O 2 ).
  • Al-containing precursor examples include trimethylaluminum ((CH 3 ) 3 Al) and the like.
  • titer containing Ti examples include bis (t-butylcyclopentadienyl) titanium (IV) dichloride (C 18 H 26 Cl2 Ti) and tetrakis (dimethylamino) titanium (IV) ([(CH 3).
  • Si-containing precursor examples include N-sec-butyl (trimethylsilyl) amine (C 7 H 19 NSi) and 1,3-diethyl-1,1,3,3-tetramethyldisilazane (C 8 H).
  • NSi 2 2,4,6,8,10-pentamethylcyclopentasiloxane ((CH 3 SiHO) 5 ), pentamethyldisilane ((CH 3 ) 3 SiSi (CH 3 ) 2 H), Tris (iso) Propoxy) silanol ([(H 3 C) 2 CHO] 3 SiOH), chloropentanemethyldisilane ((CH 3 ) 3 SiSi (CH 3 ) 2 Cl), dichlorosilane (SiH 2 Cl 2 ), tridimethylaminosilane (Si) [N (CH 3 ) 2 ] 4 ), tetraethylsilane (Si (C 2 H 5 ) 4 ), tetramethylsilane (Si) (
  • precursors containing Ta include (t-butylimide) tris (ethylmethylamino) tantalum (V) (C 13 H 33 N 4 Ta, TBTEMT) and tantalum (V) pentaethoxydo (Ta (OC 2). H 5 ) 5 ), (t-butylimide) Tris (diethylamino) tantalum (V) ((CH 3 ) 3 CNTa (N (C 2 H 5 ) 2 ) 3 ), Pentakis (dimethylamino) tantalum (V) (Ta) (N (CH 3 ) 2 ) 5 ) and the like can be mentioned.
  • Nb niobium (V) ethoxydo (Nb (OCH 2 CH 3 ) 5 , tris (diethylamide) (t-butylimide) niobium (V) (C 16 H 39 N 4 Nb)).
  • V niobium
  • Nb OCH 2 CH 3
  • V tris (diethylamide)
  • t-butylimide niobium
  • HfCl 4 hafnium tetrachloride
  • Hf [N (CH 3 ) 2 ] 4 tetrakisdimethylaminohafnium
  • Hf [N (C 2 H 5 )) ( CH 3 )] 4 tetrakisethylmethylaminohafnium
  • Hf [OC (CH 3 ) 3 ] 4 hafnium-t-butoxide
  • precursors containing Zr include bis (methyl- ⁇ 5 cyclopentadienyl) methoxymethyl zirconium (Zr (CH 3 C 5 H 4 ) 2 CH 3 OCH 3 ) and tetrakis (dimethylamide) zirconium (IV). ) ([(CH 3 ) 2 N] 4 Zr), tetrakis (ethylmethylamide) zirconium (IV) (Zr (NCH 3 C 2 H 5 ) 4 ) , zirconium (IV) t-butoxide (Zr [OC (CH)) 3 ) 3 ] 4 ) and so on.
  • the film containing the first layer and / or the second layer can be formed to a depth of 10% or more of the thickness of the porous metal portion in the thickness direction of the porous metal portion.
  • the second layer may be formed by chemical conversion treatment of the cathode foil. The details of the chemical conversion treatment will be described later.
  • Process (iii) The step (iii) of adhering at least one of phosphorus and nitrogen to the surface of the porous metal portion is performed, for example, by impregnating the porous metal portion with a solution containing at least one of phosphorus and nitrogen.
  • a solution containing at least one of phosphorus and nitrogen By the subsequent heat treatment, phosphorus and / or nitrogen adhering to the inner side wall of the pores diffuses into the metal porous portion, and a layer containing at least one of phosphorus and nitrogen (third layer) is formed on the surface of the metal porous portion.
  • the third layer can increase the water resistance of the electrolytic capacitor.
  • the impregnation of the solution containing at least one of phosphorus and nitrogen may be carried out in the process of forming the cathode foil.
  • the pores can be impregnated with a solution containing a phosphorus compound or a nitrogen compound in parallel with the growth of the oxide film on the inner side wall of the pores. In this case, as the oxide film grows on the inner side wall of the pores, phosphorus and / or nitrogen diffuses into the oxide film, and the oxide film containing phosphorus and / or nitrogen grows.
  • the third layer may be formed by impregnating the chemically formed cathode foil with a solution containing at least one of phosphorus and nitrogen.
  • a solution containing at least one of phosphorus and nitrogen By the subsequent heat treatment, phosphorus and / or nitrogen adhering to the inner side wall of the pores diffuses inside the chemical oxide film, and a third layer containing phosphorus and / or nitrogen grows on at least the surface layer of the oxide film.
  • the cathodic foil that has already been chemically formed may be chemically formed again using a chemical conversion solution containing at least one of phosphorus and nitrogen.
  • the voltage applied to the cathode at the time of re-chemical conversion may be higher or lower than the voltage applied in the previous chemical conversion treatment.
  • the oxide film does not grow further, but the diffusion of phosphorus and / or nitrogen into the oxide film is promoted.
  • the third layer can be formed thickly.
  • the phosphorus and / nitrogen content in the third layer can be increased.
  • the chemical conversion treatment can be performed, for example, by applying a positive voltage to the metal foil while the cathode foil is immersed in the chemical conversion liquid. At this time, if necessary, chemical conversion treatment may be performed under temperature conditions of, for example, 50 to 85 ° C.
  • Examples of the chemical conversion liquid include an aqueous solution containing phosphoric acid, adipic acid, boric acid, oxalic acid, sulfuric acid and / or salts thereof.
  • the phosphate contains phosphorus, the third layer containing phosphorus can be grown by chemical conversion treatment.
  • Examples of the phosphate include ammonium phosphate salt, potassium phosphate salt, sodium phosphate salt and the like.
  • Examples of the chemical conversion solution containing nitrogen include an aqueous solution containing an ammonium salt.
  • the ammonium salt may be a primary ammonium salt, a secondary ammonium salt, a tertiary ammonium salt, or a quaternary ammonium salt in which one or more hydrogen atoms of the ammonium cation are substituted with an organic functional group. ..
  • the ammonium phosphate salt contains both phosphorus and nitrogen, a third layer containing phosphorus and nitrogen can be easily formed, which is preferable.
  • Examples of the ammonium phosphate salt include diammonium monohydrogen phosphate and monoammonium dihydrogen phosphate.
  • the chemical conversion solution may contain one kind of salt containing phosphorus and / or nitrogen, and may contain two or more kinds.
  • the chemical conversion solution may contain salts such as adipates and borates, or salts containing neither phosphorus nor nitrogen such as potassium salts and sodium salts. From the viewpoint of workability and the like, it is preferable to use an ammonium phosphate aqueous solution such as an ammonium dihydrogen phosphate aqueous solution, an ammonium adipate aqueous solution, or the like.
  • the formation of the third layer may be performed before the formation of the first layer (and / or the second layer) by the ALD method, or the first layer by the ALD method (and / or the second layer). And / or after the formation of the second layer).
  • the third layer is formed over the entire depth of the metal porous portion, and the third layer may intervene between the first layer and the second layer and the metal porous portion.
  • phosphorus or nitrogen is difficult to diffuse into the metal porous portion from the outer surface of the metal porous portion on which the first layer is already formed.
  • the third layer can be formed exclusively in the deep portion on the metal core portion side of the metal porous portion in which the first layer is not formed. In either case, the third layer may adhere to a region having a depth of more than 10% of the thickness of the porous metal portion in the thickness direction of the porous metal portion.
  • the cathode foil after the chemical conversion treatment may be washed and dried, if necessary.
  • Phosphorus compounds attached to the cathode foil (e.g., PO 4 3-) content can be analyzed by ion chromatography.
  • the content of the phosphorus compound adhered to the cathode body for example, 3 mg / m 2 or more 300 mg / m 2 or less, 5 mg / m 2 or more 100 mg / m 2 or less.
  • the cathode foil is prepared by cutting the treated metal foil to a desired size.
  • a metal foil containing a valve acting metal which is a raw material of the anode is prepared, and the surface of the metal foil is roughened. Due to the roughening, a plurality of irregularities are formed on the surface of the metal foil.
  • the roughening is preferably performed by etching the metal foil.
  • the etching process may be performed by, for example, a DC electrolysis method or an AC electrolysis method.
  • a dielectric layer is formed on the surface of the roughened metal foil.
  • the forming method is not particularly limited, but it can be formed by chemical conversion treatment of a metal foil. By the chemical conversion treatment of the metal foil, the surface of the metal foil is oxidized to form a dielectric layer which is an oxide film.
  • the chemical conversion treatment can be performed using, for example, a chemical conversion solution.
  • the chemical conversion treatment can be carried out by immersing the metal foil in the chemical conversion liquid and heat-treating it. The temperature at this time is, for example, 50 to 80 ° C. Further, the chemical conversion treatment may be performed by immersing the metal foil in the chemical conversion liquid and applying a voltage. During the chemical conversion treatment, both heat treatment and application of voltage may be performed.
  • the chemical conversion solution can be appropriately determined from the one described for the chemical conversion of the cathode body. The anode body after the chemical conversion treatment may be washed and dried, if necessary.
  • the anode is prepared by cutting the treated metal leaf to a desired size.
  • the cut anode has a dielectric layer on its main surface.
  • Step (v) Subsequently, a capacitor element is formed by using the anode body and the cathode foil for the electrolytic capacitor (step (v)).
  • a wound body is produced using the cathode foils obtained in steps (i) to (iii) and the anode body prepared in step (iv).
  • the anode body 21 and the cathode foil are wound around the separator 23.
  • the lead tabs 15A and 15B can be planted from the winding body as shown in FIG.
  • the materials of the lead tabs 15A and 15B are not particularly limited, and may be any conductive material.
  • the materials of the lead wires 14A and 14B connected to the lead tabs 15A and 15B are not particularly limited, and may be any conductive material.
  • the winding stop tape 24 is arranged on the outer surface of the cathode foil located on the outermost layer of the wound anode body 21, the cathode foil, and the separator 23, and the end portion of the cathode body is covered with the winding stop tape 24. Fix it.
  • the third layer may be formed on the cathode foil after the wound body is formed.
  • the wound body is impregnated with a solution containing at least one of phosphorus and nitrogen to attach at least one of phosphorus and nitrogen to the surface of the metal porous portion of the cathode foil.
  • phosphorus and / or nitrogen adhering to the inner side wall of the pores can be diffused into the metal porous portion, and a third layer can be formed on the surface of the metal porous portion.
  • the chemical conversion treatment may be performed by heat-treating the wound body in a state of being immersed in the chemical conversion liquid.
  • this may be performed by applying a positive voltage to the anode body of the wound body with the third electrode as the counter electrode in a state where the third electrode is immersed in the chemical conversion solution together with the wound body. Both heat treatment and application of voltage may be performed.
  • the temperature conditions of the chemical conversion liquid and the chemical conversion treatment can be appropriately determined from those described for the step (iii).
  • the chemical conversion treatment may be carried out in a state where the entire wound body is immersed in the chemical conversion liquid, or at least the top surface and the bottom surface of the wound body may be immersed in the chemical conversion liquid. The wound body after the chemical conversion treatment is washed and dried, if necessary.
  • phosphorus and / or nitrogen may also adhere to the surface of the first layer or the second layer. This allows cracks that may be present on the surface of the first or second layer to be covered with a layer containing phosphorus and / or nitrogen.
  • the liquid component invades the metal core through the crack and easily deteriorates the cathode foil.
  • ESR may increase.
  • the third layer containing phosphorus and / or nitrogen after the formation of the first layer or the second layer, the inner side wall of the pores in the deep part of the metal porous portion is covered with the third layer, and the first layer is formed.
  • the crack formed in the layer or the second layer can be covered with the third layer.
  • the third layer may be formed to fill cracks that may be present in the first and / or second layer.
  • a step of adhering the conductive polymer to the winding body can be performed.
  • the conductive polymer is attached so as to cover at least a part of the dielectric layer of the anode body 21.
  • the conductive polymer adheres to the surface of the dielectric layer of the anode 21 in a layered manner to form a conductive polymer layer (or solid electrolyte layer). It may be formed, but it is not limited to this case.
  • the conductive polymer may cover at least a part of the surface of the separator 23. Further, the conductive polymer may be formed so as to fill the pores of the cathode body.
  • the conductive polymer those described above can be used.
  • the conductive polymer may be attached to the winding body by applying a solution containing a monomer, a dopant, an oxidizing agent, etc. to the capacitor element and chemically polymerizing or electrolytically polymerizing the conductive polymer on the spot. Further, the conductive polymer may be attached to the winding body by a method of applying a treatment liquid containing a conductive polymer (hereinafter, also simply referred to as a polymer dispersion) to the winding body.
  • a treatment liquid containing a conductive polymer hereinafter, also simply referred to as a polymer dispersion
  • the concentration of the conductive polymer contained in the polymer dispersion is preferably 0.5 to 10% by mass.
  • the average particle size D50 of the conductive polymer is preferably 0.01 to 0.5 ⁇ m, for example.
  • the average particle size D50 is the median diameter in the volume particle size distribution obtained by the particle size distribution measuring device by the dynamic light scattering method.
  • the polymer dispersion contains a liquid dispersion medium and a conductive polymer dispersed in the liquid dispersion medium.
  • the polymer dispersion may be a solution in which a conductive polymer is dissolved in a liquid dispersion medium, or a dispersion in which particles of the conductive polymer are dispersed in a liquid dispersion medium. After impregnating the wound body with the treatment liquid, it is usually dried to volatilize at least a part of the liquid dispersion medium.
  • the acid may be dissolved in the liquid dispersion medium in order to suppress the dedoping of the conductive polymer.
  • the acid phosphoric acid, sulfuric acid, phthalic acid, benzoic acid, nitrobenzoic acid, salicylic acid, trimellitic acid, pyromellitic acid and the like are preferable.
  • the polymer dispersion can be obtained, for example, by a method of dispersing a conductive polymer in a liquid dispersion medium, a method of polymerizing a precursor monomer in a liquid dispersion medium to generate particles of the conductive polymer, or the like.
  • Preferred polymer dispersions include, for example, polystyrene sulfonic acid (PSS) -doped poly (3,4-ethylenedioxythiophene) (PEDOT), i.e. PEDOT / PSS.
  • PSS polystyrene sulfonic acid
  • PEDOT polyethylenedioxythiophene
  • an antioxidant of a conductive polymer may be added, it is not necessary to use an antioxidant because PEDOT / PSS hardly oxidizes.
  • the liquid dispersion medium may be water, a mixture of water and a non-aqueous solvent, or a non-aqueous solvent.
  • the non-aqueous solvent is not particularly limited, and for example, a protic solvent or an aprotic solvent can be used.
  • the protonic solvent include alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol, and ethers such as formaldehyde and 1,4-dioxane.
  • aprotic solvent examples include amides such as N-methylacetamide, N, N-dimethylformamide and N-methyl-2-pyrrolidone, esters such as methyl acetate, and ketones such as methyl ethyl ketone.
  • a method of imparting (impregnating) the polymer dispersion to the winding body for example, a method of immersing the winding body in the polymer dispersion contained in the container is simple and preferable. Further, ultrasonic vibration may be applied to the wound body or the polymer dispersion while being immersed in the polymer dispersion.
  • the drying after pulling up the wound body from the polymer dispersion is preferably performed at, for example, 50 to 300 ° C.
  • the step of applying the polymer dispersion to the wound body and the step of drying the wound body may be repeated twice or more. By performing these steps a plurality of times, the coverage of the conductive polymer in the wound body can be increased.
  • the capacitor element 10 to which the conductive polymer is attached so as to cover at least a part of the dielectric layer can be obtained.
  • the conductive polymer formed on the surface of the dielectric layer functions as a de facto cathode material.
  • the method of impregnating the capacitor element 10 with a liquid component is not particularly limited.
  • a method of immersing the capacitor element 10 in a liquid component contained in a container is simple and preferable.
  • the impregnation is preferably carried out under reduced pressure, for example, in an atmosphere of 10 to 100 kPa.
  • the liquid component include the above-mentioned materials.
  • the capacitor element 10 is sealed. Specifically, first, the capacitor element 10 is housed in the bottomed case 11 so that the lead wires 14A and 14B are located on the upper surface of the bottomed case 11 that opens.
  • the material of the bottomed case 11 metals such as aluminum, stainless steel, copper, iron, and brass, or alloys thereof can be used.
  • the sealing member 12 formed so that the lead wires 14A and 14B penetrate is arranged above the capacitor element 10, and the capacitor element 10 is sealed in the bottomed case 11.
  • a horizontal drawing process is performed in the vicinity of the open end of the bottomed case 11, and the open end is crimped to the sealing member 12 to be curled.
  • the electrolytic capacitor as shown in FIG. 5 is completed.
  • the aging process may be performed while applying the rated voltage.
  • the sealing member 12 is made of an elastic material containing a rubber component.
  • a rubber component butyl rubber (IIR), nitrile rubber (NBR), ethylene propylene rubber, ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), isoprene rubber (IR), hyperon rubber, silicone rubber, fluorine rubber, etc.
  • the sealing member 12 may contain a filler such as carbon black or silica.
  • further chemical conversion treatment may be performed to form a dielectric layer on the anode body or an oxide film on the cathode body.
  • the chemical conversion treatment at this time can be performed using an electrolytic solution.
  • the chemical conversion treatment can be performed, for example, by applying a positive voltage to the anode body or the cathode body while the capacitor element 10 is immersed in the electrolytic solution.
  • heat treatment is also usually performed together.
  • the temperature of the heat treatment is, for example, 80 to 150 ° C.
  • the present invention can be used for electrolytic capacitors.
  • Capacitor element 11 Bottomed case 12: Sealing member 13: Seat plate 14A, 14B: Lead wire 15A, 15B: Lead tab 21: Anode body 22, 22A, 22B: Cathode foil 31: Metal core 32: Porous metal Quality part 33: Film 35: 1st layer 36: 2nd layer 37: 3rd layer 38: Pore 23: Separator 24: Winding tape

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PCT/JP2020/044131 2019-11-29 2020-11-27 電解コンデンサ用陰極箔、電解コンデンサ、および、これらの製造方法 Ceased WO2021107063A1 (ja)

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