Electrolytic capacitor

Abstract

The electrolytic capacitor of this application comprises a capacitor element and a liquid component. The capacitor element comprises: an anode foil having a dielectric layer; a cathode foil disposed opposite to the dielectric layer; a spacer between the anode foil and the cathode foil; and a conductive polymer layer disposed between the anode foil and the cathode foil and in contact with the spacer. The liquid component comprises a polymer compound, the polymer compound comprising a first component having a mass-average molecular weight Mw of 200 or more and 2000 or less, and the polydispersity (Mw / Mn) ratio of the mass-average molecular weight Mw to the number-average molecular weight Mn is 1.35 or less.

Description

Technical Field

[0001] This invention relates to electrolytic capacitors. More specifically, this invention relates to electrolytic capacitors having a liquid component and a conductive polymer layer. Background Technology

[0002] Previously, there was a known electrolytic capacitor which had a capacitor element formed by winding an anode electrode foil with a dielectric oxide film formed thereon and a cathode electrode foil with a spacer in between.

[0003] As described above, hybrid electrolytic capacitors (such as Patent Document 1 below) are known to possess both a conductive polymer layer and a liquid component (e.g., electrolyte). Hybrid electrolytic capacitors have the following advantages: the conductive polymer layer can reduce the equivalent series resistance (ESR) (ESR reduction), and the liquid component can improve the repairability of the dielectric oxide film.

[0004] In recent years, various studies have been conducted to improve the characteristics of hybrid electrolytic capacitors. For example, Patent Document 1 below proposes a hybrid electrolytic capacitor that uses an electrolyte comprising a first solvent selected from γ-valerol, γ-butyrolactone, δ-valerol, and α-methyl-γ-butyrolactone, a second solvent selected from polyalkylene glycols and their derivatives with a number average molecular weight of 100 to 250, and a third solvent selected from polyalkylene glycols and their derivatives with a number average molecular weight of 500 to 2000. That is, a hybrid electrolytic capacitor using an electrolyte comprising a first solvent as a volatile solvent (low viscosity solvent), a second solvent as a non-volatile solvent, and a third solvent is proposed. Furthermore, it is described that in a hybrid electrolytic capacitor using such an electrolyte, it is possible to simultaneously reduce the rate of change of electrostatic capacitance in the low-temperature region (specifically, -55°C) (the rate of reduction of electrostatic capacitance in the low-temperature region relative to the electrostatic capacitance at 25°C) and reduce ESR in the high-temperature region (e.g., 135°C).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-69390 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] As mentioned above, in electrolytic capacitors containing polymeric compounds such as polyalkylene glycols as liquid components (electrolytes, etc.), sometimes the characteristics of multiple electrolytic capacitors deviate from each other. Especially when multiple electrolytic capacitors are used separately at high temperatures (e.g., at 145°C for 1000 hours), sometimes large deviations in the electrostatic capacitance between these multiple electrolytic capacitors occur. Therefore, from a quality assurance point of view, large deviations in the electrostatic capacitance between multiple electrolytic capacitors are undesirable. However, in electrolytic capacitors using liquid components containing polymeric compounds, it is difficult to say that sufficient research has been conducted to reduce the deviations in the electrostatic capacitance between multiple electrolytic capacitors.

[0010] Therefore, this application provides an electrolytic capacitor that can reduce the deviation of electrostatic capacitance even when using liquid components containing polymer compounds.

[0011] Methods for solving problems

[0012] One aspect of the present invention relates to an electrolytic capacitor comprising a capacitor element and a liquid component, the capacitor element comprising: an anode foil having a dielectric layer; a cathode foil disposed opposite to the dielectric layer; a spacer disposed between the anode foil and the cathode foil; and a conductive polymer layer disposed between the anode foil and the cathode foil and in contact with the spacer, the liquid component comprising a polymer compound comprising a first component having a mass-average molecular weight Mw of 200 or more and 2000 or less, and the polydispersity (Mw / Mn) ratio of the mass-average molecular weight Mw to the number-average molecular weight Mn is 1.35 or less.

[0013] Invention Effects

[0014] According to this application, it is possible to provide an electrolytic capacitor that can reduce the deviation of electrostatic capacitance even when using liquid components containing polymer compounds. Attached Figure Description

[0015] Figure 1 This is a cross-sectional schematic diagram of an electrolytic capacitor according to one embodiment of this application.

[0016] Figure 2 It is Figure 1 A schematic diagram showing a portion of the capacitor elements of an electrolytic capacitor. Detailed Implementation

[0017] The following description illustrates embodiments of this application using examples, but this application is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes illustrated, but other numerical values, materials, etc., can also be applied as long as the desired effect of this application is achieved. It should be noted that known constituent elements can also be applied to the constituent elements of the characteristic portion of this application. In this specification, when referred to as the "range of numerical value A to numerical value B," this range includes both numerical value A and numerical value B.

[0018] In the following description, when lower and upper limits of values ​​related to specific physical properties, conditions, etc. are given, any of the given lower limits can be combined with any of the given upper limits as long as the lower limit is not above the upper limit. When multiple materials are given, unless otherwise specified, one of them can be selected and used alone, or two or more can be combined.

[0019] Furthermore, this application includes a combination of matters described in any two or more technical solutions selected from the plurality of technical solutions described in the appended claims. That is, as long as no technical contradiction arises, a combination of matters described in any two or more technical solutions selected from the plurality of technical solutions described in the appended claims is permissible.

[0020] Electrolytic capacitors

[0021] The electrolytic capacitor of this application is an electrolytic capacitor comprising a capacitor element and a liquid component. In the electrolytic capacitor of this application, the capacitor element comprises: an anode foil having a dielectric layer, a cathode foil disposed opposite to the dielectric layer, a spacer between the anode foil and the cathode foil, and a conductive polymer layer disposed between the anode foil and the cathode foil and in contact with the spacer. In the electrolytic capacitor of this application, the liquid component comprises a polymer compound, which comprises a first component having a mass-average molecular weight Mw of 200 or more and 2000 or less, and the polydispersity (Mw / Mn) of the mass-average molecular weight Mw to the number-average molecular weight Mn is 1.35 or less.

[0022] As described above, the electrolytic capacitor of this embodiment includes a liquid component. The liquid component is contained within the voids of the capacitor element. The liquid component only needs to fill at least a portion of the voids within the capacitor element.

[0023] <Liquid Components>

[0024] The liquid component includes a non-aqueous solvent and an electrolyte. As the electrolyte, a non-aqueous electrolyte containing a non-aqueous solvent and a solute dissolved in that non-aqueous solvent can be used. Various known non-aqueous solvents and solutes used in electrolytic capacitors can be used as the non-aqueous solvent and solute. The liquid component can be liquid at room temperature (25°C) or at the temperature at which the electrolytic capacitor is used.

[0025] Non-aqueous solvents can be organic solvents or ionic liquids.

[0026] Examples of organic solvents include glycol compounds, sulfone compounds, and lactone compounds. Examples of glycol compounds include ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), and propylene glycol (PG). Examples of sulfone compounds include sulfolane (SL), dimethyl sulfoxide (DMSO), and diethyl sulfoxide (DESO). Examples of lactone compounds include γ-butyrolactone (GBL) and γ-valerolactone (GVL).

[0027] Examples of organic solvents include carbonate compounds and alcohols with one or more nucleotides. Examples of carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate (FEC). Examples of alcohols with one or more nucleotides include glycerol and polyglycerol. They can be used individually or in combination of two or more.

[0028] In organic solvents, when Group 1 consists of diol compounds, sulfone compounds, and lactone compounds, and Group 2 consists of carbonate compounds and mono- or tri- or more alcohols, the organic solvents belonging to Group 1 preferably contain more than 50% by mass, more preferably more than 60% by mass, and even more preferably more than 70% by mass. All organic solvents can be dominated by organic solvents belonging to Group 1. That is, organic solvents belonging to Group 1 can be the main solvent, and organic solvents belonging to Group 2 can be secondary solvents.

[0029] The liquid component preferably contains at least one of a diol compound and a sulfone compound as an organic solvent. If the liquid component contains at least one of these compounds, the re-chemical conversion of the dielectric layer based on the acid component contained in the liquid component can be carried out efficiently. Furthermore, by including a diol compound in the liquid component, protons (H+) from the diol compound can be readily supplied to the conductive polymer constituting the conductive polymer layer. ＋ (Specifically, the protons (H) contained in the hydroxyl group) ＋This makes it particularly easy for the conductive polymer layer to swell. By including a sulfone compound in the liquid component, the liquid component exhibits high resistance to acidic and alkaline components. Furthermore, glycol compounds and sulfone compounds typically have high boiling points (specifically, boiling points above 180°C). Therefore, if the liquid component contains these compounds, it is less likely to volatilize even when using electrolytic capacitors at high temperatures (e.g., 145°C). As the glycol compound mentioned above, ethylene glycol (EG) is preferably included, and as the sulfone compound mentioned above, sulfolane (SL) is preferably included.

[0030] When the liquid component contains a diol compound and a sulfone compound as an organic solvent, the proportion of the diol compound in the liquid component is preferably 10% by mass or more and 60% by mass or less, and the proportion of the sulfone compound in the liquid component is preferably 20% by mass or more and 70% by mass or less. By including the diol compound and the sulfone compound within the above-mentioned numerical range, the re-chemical conversion of the dielectric layer based on the acid component contained in the liquid component can be carried out more efficiently. In addition, the proton supply to conductive polymers can be further improved, and the resistance of the liquid component to acid and alkali components can be further improved.

[0031] From the perspective of supplying protons to conductive polymers, the liquid component can contain compounds other than glycol compounds. Examples of such other compounds include glycerol and polyglycerol.

[0032] The liquid component may contain water. The water content in the liquid component can be 0.1% by mass or more and 6.0% by mass or less, or 0.2% by mass or more and 4.0% by mass or less, or 0.5% by mass or more and 2.0% by mass or less. By including water in the liquid component within the ranges described above, the repairability of the dielectric layer based on the liquid component can be improved. Furthermore, when using electrolytic capacitors at high temperatures (e.g., after 1000 hours of use at 145°C), fluctuations in the equivalent series resistance (ESR) can be suppressed. It should be noted that sulfone compounds have excellent hydrolysis resistance; therefore, as described above, including sulfone compounds in the liquid component can improve the hydrolysis resistance of the liquid component.

[0033] The solute includes at least one of an acidic component (acid) and a basic component (base). When the liquid component contains a solute, the proportion of the solute in the liquid component is preferably 70% by mass or less, more preferably 50% by mass or less.

[0034] As acid components, polycarboxylic acids and monocarboxylic acids can be used. Examples of polycarboxylic acids include aliphatic polycarboxylic acids, aromatic polycarboxylic acids, and alicyclic polycarboxylic acids. Examples of aliphatic polycarboxylic acids include saturated and unsaturated polycarboxylic acids. Examples of saturated polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, and 5,6-decanedicarboxylic acid. Examples of unsaturated polycarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of aromatic polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid. Examples of alicyclic polycarboxylic acids include cyclohexane-1,2-dicarboxylic acid and cyclohexene-1,2-dicarboxylic acid.

[0035] Examples of monocarboxylic acids include aliphatic monocarboxylic acids, aromatic monocarboxylic acids, and hydroxycarboxylic acids. Examples of aliphatic monocarboxylic acids include saturated and unsaturated monocarboxylic acids. Examples of saturated monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, lauric acid, myristic acid, stearic acid, and behenic acid. Examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, and oleic acid. Examples of aromatic monocarboxylic acids include benzoic acid, cinnamic acid, and naphtholic acid. Examples of hydroxycarboxylic acids include salicylic acid, mandelic acid, and resorcinolic acid.

[0036] Inorganic acids can be used as the acid component. Examples of inorganic acids include phosphoric acid, phosphorous acid, hypophosphite, alkyl phosphates, boric acid, fluoroboric acid, tetrafluoroboric acid, hexafluorophosphate, benzenesulfonic acid, and naphthalenesulfonic acid. Alternatively, complex compounds of organic and inorganic acids can be used as the acid component. Examples of such complex compounds include dicarboxylic acid derivatives such as borodiethylene glycol acid, borodioxalic acid, and borodisalicylic acid.

[0037] The base component can be a compound with an alkyl-substituted amidine group, such as imidazole compounds, benzimidazole compounds, alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds), etc. Specifically, 1,8-diazabicyclo[5,4,0]undecene-7; 1,5-diazabicyclo[4,3,0]nonene-5; 1,2-dimethylimidazolineon; 1,2,4-trimethylimidazoline; 1-methyl-2-ethylimidazoline; 1,4-dimethyl-2-ethylimidazoline; 1-methyl-2-heptylimidazoline; 1-methyl-2-(3'-heptyl)imidazoline; 1-methyl-2-dodecylimidazoline; 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine; 1-methylimidazolium; 1-methylbenzimidazole. By using these compounds, the impedance characteristics of the electrolytic capacitor can be made excellent.

[0038] As a base component, quaternary salts of compounds having alkyl-substituted amidine groups can be used. Examples of such base components include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds) that have been quaternized by alkyl or arylalkyl groups having 1 to 11 carbon atoms. Specifically, preferred materials include 1-methyl-1,8-diazabicyclo[5,4,0]undecene-7; 1-methyl-1,5-diazabicyclo[4,3,0]nonene-5; 1,2,3-trimethylimidazoline; 1,2,3,4-tetramethylimidazoline; 1,2-dimethyl-3-ethylimidazoline; 1,3,4-trimethyl-2-ethylimidazoline; 1,3-dimethyl-2-heptylimidazoline; 1,3-dimethyl-2-(3'heptyl)imidazoline, 1,3-dimethyl-2-dodecylimidazoline; 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidineonium; 1,3-dimethylimidazoline; 1-methyl-3-ethylimidazoline; and 1,3-dimethylbenzimidazolium. By using them, the impedance characteristics of electrolytic capacitors can also be made excellent.

[0039] Tertiary amines can be used as the base component. Examples of tertiary amines include trialkylamines and phenyl-containing amines. Examples of trialkylamines include trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl-n-propylamine, dimethylisopropylamine, methylethyl-n-propylamine, methylethylisopropylamine, diethyl-n-propylamine, diethylisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, and tri-tert-butylamine. Examples of phenyl-containing amines include dimethylaniline, methylethylaniline, and diethylaniline. From the viewpoint of improving conductivity, trialkylamines are preferred, and among trialkylamines, at least one selected from trimethylamine, dimethylethylamine, methyldiethylamine, and triethylamine is preferred. As the base component, secondary amines such as dialkylamines, primary amines such as monoalkylamines, and ammonia can be used.

[0040] Heterocyclic amines can be used as the base component. Examples of heterocyclic amines include morpholines, and examples of morpholines include morpholines and morpholine derivatives. Specifically, examples include morpholines, N-alkylmorpholines, and N-hydroxyalkylmorpholines. Examples of N-alkylmorpholines include N-methylmorpholine, N-butylmorpholine, and 4-isobutylmorpholine.

[0041] Liquid components can contain salts that are both acidic and basic. Salts can be inorganic or organic. Organic salts are those in which at least one of the anion and cation contains an organic compound. Examples of organic salts include trimethylamine maleate, triethylamine borosalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazoline phthalate, and mono-1,3-dimethyl-2-ethylimidazoline phthalate.

[0042] In the electrolytic capacitor of the embodiments of this application, as described above, when the liquid component contains at least one of a diol compound and a sulfone compound as an organic solvent, it is preferable that the liquid component contains at least one of a dicarboxylate and a dicarboxylate derivative as a solute. By including the above-mentioned components in the liquid component, the re-chemical transformation of the dielectric layer based on the acid component contained in the liquid component can be sufficiently carried out. In addition, since the pH of the liquid component can be maintained at a low level, the degradation of the conductive polymer layer can be suppressed. Examples of dicarboxylates include triethylamine maleate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazoline phthalate, and mono-1,3-dimethyl-ethylimidazoline phthalate, as exemplified above. Examples of dicarboxylate derivatives include borodiglycolic acid, borodioxalic acid, and borodisalicylic acid, as exemplified above.

[0043] Ionic liquids and molten salts (molten salts) have the same meaning; for example, ionic substances that are liquid at 25°C.

[0044] Examples of cations constituting ionic liquids include nitrogen-containing heterocyclic cations (imidazolium, pyrrolidineium, piperidinium, pyridinium, morpholinium, etc.), ammonium, phosphonium, sulfonium, and their derivatives (substitutes with alkyl or other substituents). Cations can be organic cations.

[0045] Examples of anions that constitute ionic liquids include the hydrogen sulfate ion (HSO4). - ), sulfate ions (SO4) 2- -SO4 - ), carboxylate anion (-COO) - ), nitrate anion, sulfonate anion (-SO3), - ), phosphonate anion (PO3) 2- -HPO3 - Examples of acids capable of generating these anions include sulfuric acid, monosulfate (methylsulfuric acid, etc.), carboxylic acids (acetic acid, lactic acid, benzoic acid, trifluoromethaneacetic acid, etc.), nitric acid, sulfonic acid (methanesulfonic acid, trifluoromethanesulfonic acid, bis(trifluoromethanesulfonyl)imine anion, etc.), phosphonic acid (diethylphosphonic acid, etc.), or their derivatives (substitutes having alkyl, haloalkyl, halogen atoms, etc.). The anion may contain a fluorine atom. Examples of fluorine-containing anions include the aforementioned trifluoromethaneacetic acid, trifluoromethanesulfonic acid, bis(trifluoromethanesulfonyl)imine anion, and their derivatives.

[0046] Specific examples of ionic liquids include 1-butyl-3-methylimidazolium hydrogen sulfate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium trifluoromethanesulfonic acid, and 1-ethyl-3-methylimidazolium diethylphosphonic acid.

[0047] The liquid component contains polymeric compounds. Examples of polymeric compounds include polyalkylene glycols, derivatives of polyalkylene glycols (polyalkylene glycol monoethers, polyalkylene glycol diethers, polyalkylene glycol monoesters, polyalkylene glycol diesters, etc.), and compounds in which at least one hydroxyl group of a polyol is replaced by a polyalkylene glycol (including derivatives). Specifically, examples include polyethylene glycol, polyethylene glycol glycerol ethers, polyethylene glycol diglycerol ethers, polyethylene glycol sorbitol ethers, polypropylene glycol, polypropylene glycol diglycerol ethers, polypropylene glycol sorbitol ethers, and polybutylene glycol.

[0048] Polyalkylene glycols can be copolymers (random copolymers, block copolymers, or random block copolymers, etc.). For example, they can be copolymers of ethylene glycol and propylene glycol, copolymers of ethylene glycol and butanediol, or copolymers of propylene glycol and butanediol.

[0049] The polymeric compound can be a copolymer having ethylene oxide (EO) units and propylene oxide (PO) units. The copolymers mentioned above include copolymers of EO and PO (EO-PO copolymers) and their derivatives. They can be used individually or in combination of two or more. The copolymers can be crosslinked using a crosslinking agent. Examples of such derivatives include those obtained by replacing the hydroxyl groups (-OH) typically present at the ends of the EO-PO copolymer with acryloyl groups (O-CO-CH=CH2). When the total amount of the EO-PO copolymer is 1 mole, the molar ratio of EO units to PO units is preferably EO:PO = 0.9:0.1 to 0.5:0.5. That is, the EO-PO copolymer preferably contains an amount of EO units equal to or greater than the amount of PO units. Therefore, in an electrolytic capacitor where the capacitor element is housed in a bottom casing and the opening of the bottom casing is sealed by a sealing member (sealing rubber, etc.), the permeation of the EO-PO copolymer contained in the liquid component through the sealing member can be suppressed.

[0050] In the electrolytic capacitor of the embodiments of this application, it is important that the polymer compound contains a first component having a mass-average molecular weight Mw of 200 or more and 2000 or less, and the polydispersity (Mw / Mn) of the ratio of mass-average molecular weight Mw to number-average molecular weight Mn is 1.35 or less.

[0051] Polymer compounds with a polydispersity ratio (Mw / Mn) of 1.35 or less refer to polymer compounds with a narrow distribution of mass-average molecular weight (Mw), i.e., polymer compounds with small deviations in mass-average molecular weight (Mw). Therefore, by using a polymer compound containing a first component with small deviations in mass-average molecular weight (Mw) as described above, the quality deviation of the liquid component can be minimized among multiple electrolytic capacitors. For example, the quality deviation of the liquid component can be minimized among multiple electrolytic capacitors manufactured using polymer compounds from the same batch (specifically, multiple electrolytic capacitors labeled with the same batch number). Furthermore, the deviation of the liquid component can be minimized among multiple electrolytic capacitors manufactured using polymer compounds from different batches (specifically, multiple electrolytic capacitors labeled with different batch numbers). Thus, deviations in the product characteristics of electrolytic capacitors can be suppressed both within the same batch and between different batches. Furthermore, although a higher mass-average molecular weight (Mw) generally corresponds to a higher polydispersity (Mw / Mn) value, the influence of mass-average molecular weight (Mw) on polydispersity (Mw / Mn) can be reduced by using a polymeric compound containing a first component with a mass-average molecular weight (Mw) of 200 or higher and 2000 or lower as the liquid component. This allows for the suppression of electrostatic capacitance deviations among multiple electrolytic capacitors.

[0052] As described above, polymeric compounds can be obtained by fractionating polymeric compounds with various mass-average molecular weights (Mw) and polydispersities (Mw / Mn) using various known methods such as precision filtration, reverse osmosis, or ultrafiltration.

[0053] The number-average molecular weight (Mn) and mass-average molecular weight (Mw) of the polymer compound are polystyrene conversion values ​​determined by gel permeation chromatography (GPC). It should be noted that GPC determination is typically performed using a polystyrene gel column and a water / methanol (8 / 2 v / v) mobile phase.

[0054] For example, the determination based on GPC can be performed as follows: using a column consisting of two connected Shodex OHpak SB804HQ and SB8025HQ columns, using 50 mM NaNO3 aqueous solution as the eluent, using an RI detector, and setting the column temperature to 40 °C, the eluent flow rate to 0.7 mL / min, and the analysis time to 40 min.

[0055] The polydispersity (Mw / Mn) can be 1.25 or less, 1.20 or less, or 1.10 or less. By including the first component within the above-mentioned numerical range in the polymer compound, the deviation in electrostatic capacitance between multiple electrolytic capacitors can be further reduced. In particular, when multiple electrolytic capacitors are used separately at high temperatures (e.g., when used at 145°C for 1000 hours), the deviation in electrostatic capacitance between multiple electrolytic capacitors can be further reduced. It should be noted that the theoretical lower limit of the polydispersity (Mw / Mn) is 1.00. The polydispersity (Mw / Mn) is preferably 1.05 or more. By making the polydispersity (Mw / Mn) 1.05 or more, the effort required for grading to obtain the first component can be reduced. In addition, since the grading effort can be reduced, the increase in manufacturing costs associated with this can be suppressed.

[0056] Polymer compounds may contain a second component in addition to the first component. The second component refers to polymer compounds in which at least one of the mass-average molecular weight (Mw) and polydispersity (Mw / Mn) is outside the range mentioned above. For example, it refers to polymer compounds with a mass-average molecular weight (Mw) of 4000 and a polydispersity (Mw / Mn) of 1.5.

[0057] In the electrolytic capacitor of the embodiments of this application, the proportion of the first component in the polymer compound is preferably more than 50% by mass, more preferably 70% by mass or more, and more preferably 90% by mass or more. The polymer compound may be entirely the first component. That is, the proportion of the first component in the polymer compound may be 100% by mass.

[0058] In the electrolytic capacitor of the embodiments of this application, the liquid component preferably contains a first component of 5% by mass or more and 30% by mass or less. By including the first component in the liquid component within the aforementioned numerical range, the liquid component possesses suitable viscosity. Therefore, even when using the electrolytic capacitor of this embodiment at high temperatures (e.g., using it at 145°C for 1000 hours), the liquid component is less likely to evaporate from the inside of the electrolytic capacitor to the outside. Furthermore, by making the liquid component possess suitable viscosity, the acid component contained in the liquid component can be used to fully facilitate the re-chemical transformation of the dielectric layer. Additionally, the electrolytic capacitor of the embodiments of this application includes a conductive polymer layer. Therefore, even if the first component is contained in the liquid component at a high concentration of up to 30% by mass, sufficient conductivity can be ensured by the conductive polymer layer. The lower limit of the proportion of the first component can be 10% by mass or more, or 15% by mass or more. The upper limit of the proportion of the first component can be 25% by mass or less, or 20% by mass or less.

[0059] <Capacitor Components>

[0060] As described above, the electrolytic capacitor of the present application includes a capacitor element in addition to the liquid component. The capacitor element includes: an anode foil having a dielectric layer, a cathode foil disposed opposite to the dielectric layer, a spacer between the anode foil and the cathode foil, and a conductive polymer layer disposed between the anode foil and the cathode foil and in contact with the spacer.

[0061] (Anode foil)

[0062] Examples of anode foils include metal foils containing at least one valve-acting metal such as titanium, tantalum, aluminum, and niobium. The anode foil can also be a metal foil containing a valve-acting metal (e.g., aluminum foil). The anode foil may contain the valve-acting metal in the form of an alloy or a compound containing the valve-acting metal. The thickness of the anode foil can be 15 μm or more and 300 μm or less. The surface of the anode foil can be roughened by etching or the like.

[0063] A dielectric layer is formed on the surface (main surface) of the anode foil. This dielectric layer can be formed by chemically converting the anode foil. In this case, the chemical conversion film formed by the chemical conversion treatment becomes the dielectric layer. The chemical conversion treatment can be performed by applying a predetermined chemical conversion voltage to the anode foil while it is immersed in an acidic aqueous solution (hereinafter also referred to as a chemical conversion solution), or by heat-treating the anode foil at a predetermined temperature while it is immersed in the chemical conversion solution. Furthermore, as described above, when the dielectric layer is formed by chemical conversion treatment, the dielectric layer (chemical conversion film) can contain an oxide of the valve-acting metal (e.g., aluminum oxide). It should be noted that the dielectric layer only needs to function as a dielectric, and it can also be formed from a dielectric other than an oxide of the valve-acting metal.

[0064] In electrolytic capacitors, a conductive polymer layer may not be formed on the end face (side face) of the anode foil. On the other hand, it is preferable to form a dielectric layer on the end face (side face) of the anode foil. If a wound-type electrolytic capacitor (see...) Figure 1 and 2 Taking ( ) as an example, then in Figure 2 In the wound capacitor element 10 shown, the conductive polymer can be formed in the circumferential direction, but not on the upper and lower end faces.

[0065] (Cathode foil)

[0066] There are no particular limitations on the cathode foil as long as it functions as a cathode. Examples of cathode foils include metal foils (e.g., aluminum foil). There are no particular limitations on the type of metal contained in the metal foil. The metal can be a valve-acting metal or an alloy containing a valve-acting metal. The thickness of the cathode foil can be 15 μm or more and 300 μm or less. The surface of the cathode foil can be roughened or chemically converted as needed.

[0067] The cathode foil may include a conductive coating. When the metal foil contains a valve-acting metal, the coating may contain at least one of carbon and a metal with a lower ionization tendency than the valve-acting metal. This readily improves the acid resistance of the metal foil. When the metal foil contains aluminum, the coating may contain at least one selected from carbon, nickel, titanium, tantalum, and zirconium. From the viewpoint of achieving low cost and low resistance, the coating may contain at least one of nickel and titanium.

[0068] The thickness of the coating layer can be 5 nm or more, or 10 nm or more. The thickness of the coating layer can be less than 200 nm. The coating layer can be formed by vapor deposition or sputtering of the aforementioned metal onto a metal foil. Alternatively, the coating layer can be formed by vapor deposition of a conductive carbon material onto a metal foil, or by coating a carbon paste containing a conductive carbon material. Examples of conductive carbon materials include graphite, hard carbon, soft carbon, and carbon black.

[0069] (spacer)

[0070] The spacer can be a porous sheet. Examples of porous sheets include fabrics, nonwoven fabrics, and microporous membranes. The thickness of the spacer is not particularly limited and can range from 10 μm to 300 μm. Examples of materials used for the spacer include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamides, polyimides, polyamide-imides, polyether-imides, rayon, and glass.

[0071] (Conductive polymer layer)

[0072] The conductive polymer layer is formed from conductive polymers. Examples of conductive polymers include polypyrrole, polythiophene, polyaniline, and their derivatives. A single conductive polymer can be used, or two or more can be used in combination. Conductive polymers can also be copolymers of two or more monomers. It should be noted that derivatives of conductive polymers refer to polymers with conductive polymers as their basic backbone. For example, derivatives of polythiophene include poly(3,4-ethylenedioxythiophene), etc.

[0073] Conductive polymers may contain dopants. The dopants can be appropriately selected depending on the type of conductive polymer. Various known dopants can be used. Examples of dopants include naphthalenesulfonic acid, p-toluenesulfonic acid, polystyrenesulfonic acid, and their salts. A specific example of a conductive polymer containing dopants is a polymer doped with polystyrenesulfonic acid (PSS) in poly(3,4-ethylenedioxythiophene) (PEDOT).

[0074] The conductive polymer layer preferably contacts the anode foil, cathode foil, and spacer with a sufficiently large contact area. This creates a sufficient conductive path between the anode and cathode foils through the conductive polymer layer. As a result, the equivalent series resistance (ESR) of the electrolytic capacitor can be reduced, thus improving the reliability of the electrolytic capacitor.

[0075] The conductive polymer layer is preferably formed on at least one of the surfaces of the dielectric layer of the anode foil and the cathode foil. The conductive polymer layer may also be formed within the voids of the spacer (i.e., on the surface of the material constituting the spacer surrounding the voids). This allows for the formation of a more robust conductive path based on the conductive polymer layer between the anode foil and the cathode foil. The conductive polymer layer is preferably formed at least on the surface of the dielectric layer of the anode foil, more preferably on both the surface of the dielectric layer and the surface of the cathode foil, and within the voids of the spacer. The conductive polymer layer is preferably formed in a manner that continuously connects the surface of the dielectric layer to the surface of the cathode foil. By continuously connecting the surface of the dielectric layer to the surface of the cathode foil, the conductive path formed between the anode foil and the cathode foil becomes more robust.

[0076] The conductive polymer layer can be formed by applying a polymer dispersion, obtained by dispersing a conductive polymer and a dopant in a liquid medium, to a dielectric layer, and then removing at least a portion of the liquid medium. Alternatively, the conductive polymer layer can be formed by impregnating a monomer dispersion containing monomers that form structural units of the conductive polymer and a dopant into a dielectric layer, and then chemically or electrolytically polymerizing the monomers in the dielectric layer in the presence of the dopant. For electrolytic capacitors to exhibit excellent voltage withstand characteristics, the conductive polymer layer is preferably formed using a polymer dispersion.

[0077] The following is for reference Figure 1 and 2 The specific configuration of an electrolytic capacitor according to one embodiment of this application will be described. Figure 1 This is a schematic cross-sectional view of an electrolytic capacitor 100 according to one embodiment of this application. Figure 2 This is a schematic diagram showing a portion of the capacitor element 10 contained in the electrolytic capacitor 100 unfolded.

[0078] The electrolytic capacitor 100 includes: a capacitor element 10, a bottomed housing 101 housing the capacitor element 10, a sealing member 102 (e.g., sealing rubber) blocking the opening of the bottomed housing 101, a base plate 103 covering the sealing member 102, a base plate 103 disposed outside the bottomed housing 101 such that it covers the sealing member 102 from the opening side of the bottomed housing 101, a pair of leads 104A, 104B extending from the sealing member 102 and passing through the base plate 103, and a pair of lead connectors 105A, 105B connecting the pair of leads 104A, 104B to the electrodes of the capacitor element (e.g., the anode foil 11 and cathode foil 12 described later), respectively. A deep drawing process is performed near the opening end of the bottomed housing 101 in an inwardly recessed manner, and a coiling process is performed at the opening end of the bottomed housing 101 in a manner that is tightly pressed against the sealing member 102. It should be noted that... Figure 1 In the example shown, lead 104A is connected to the electrode of the capacitor element via lead connector 105A, and lead 104B is connected to the electrode of the capacitor element via lead connector 105B.

[0079] The sealing member 102 is formed of an elastic material containing a rubber component. As the rubber component, butyl rubber (IIR), nitrile rubber (NBR), ethylene propylene rubber, ethylene propylene diene monomer (EPDM), chloroprene rubber (CR), isoprene rubber (IR), Hypalon rubber, silicone rubber, fluororubber, etc., can be used. The sealing member 102 may contain fillers such as carbon black and silica.

[0080] Capacitor element 10 is configured, for example, as follows: Figure 2 The wound body shown. The wound body includes an anode foil 11 connected to lead connector 105A, a cathode foil 12 connected to lead connector 105B, and a spacer 13. The capacitor element 10 includes a conductive polymer layer (not shown). It should be noted that... Figure 1 The electrolytic capacitor 100 shown includes Figure 2 The capacitor element 10 shown is therefore called a wound electrolytic capacitor.

[0081] The anode foil 11 and the cathode foil 12 are wound together to form a wound body, with a spacer 13 sandwiched between them. Furthermore, the outermost periphery of this wound body is secured by a winding fixing tape 14. It should be noted that... Figure 2 This indicates the state of the coiled body before the outermost periphery is fixed by the winding fixing tape 14.

[0082] The electrolytic capacitor of this application may have at least one capacitor element, or may have multiple capacitor elements. The number of capacitor elements in the electrolytic capacitor is appropriately determined according to the application.

[0083] exist Figure 1 and 2 The previous description described a wound electrolytic capacitor, but the electrolytic capacitor in the embodiments of this application is not limited to this. It can be a chip-type electrolytic capacitor or a stacked electrolytic capacitor.

[0084] [Manufacturing method of electrolytic capacitors]

[0085] An example of a method for manufacturing an electrolytic capacitor according to an embodiment of this application includes: (a) a step of preparing an anode foil, a cathode foil, and a spacer having a dielectric layer; (b) a step of depositing a polymer dispersion, formed by dispersing a conductive polymer and a dopant in a liquid medium, onto the surface of at least one of the dielectric layer and the cathode foil and into the voids of the spacer; (c) a step of forming a conductive polymer layer on the surface of one of the electrodes and into the voids of the spacer by removing at least a portion of the liquid medium from the polymer dispersion; (d) a step of forming a capacitor element by distributing a spacer between the anode foil and the cathode foil; and (e) a step of filling the voids within the capacitor element with a liquid component. In the method for manufacturing an electrolytic capacitor according to an embodiment of this application, steps (a) to (e) are preferably performed sequentially.

[0086] <(a) Process>

[0087] There are no particular limitations on the process for preparing the anode foil, cathode foil, and spacer with dielectric layers. There are also no particular limitations on the materials used for the anode foil, cathode foil, and spacer. The anode foil, cathode foil, and spacer described above can be used as the anode foil, cathode foil, and spacer.

[0088] <(b) Process>

[0089] In step (b), a polymer dispersion can be applied to the surface of the dielectric layer and the spacers, or to the surface of the cathode foil and the spacers. Alternatively, a polymer dispersion can be applied to the surface of the dielectric layer, the surface of the cathode foil, and the spacers. It should be noted that when a dielectric layer is formed on both sides of the anode foil, the polymer dispersion can be applied to the surface of the dielectric layer formed on both sides of the dielectric layer. Furthermore, the polymer dispersion can be applied to both sides of the cathode foil. A conductive polymer layer is formed at the sites where the polymer dispersion is applied.

[0090] One method for applying a polymer dispersion is coating. Coating can be carried out by various known methods. Examples of coating include coating using a coating machine, spray-based coating, and coating in which the object to be coated is immersed in the polymer dispersion. Examples of coating using a coating machine include gravure coating and die coating. It should be noted that water is a liquid medium, for example.

[0091] <(c) Process>

[0092] In step (c), the method for removing at least a portion of the liquid medium from the polymer dispersion is not particularly limited. The removal of the liquid medium is preferably carried out at least by heating. The removal of the liquid medium can be carried out by heating under reduced pressure. It should be noted that, in the case of water as the liquid medium, the removal of the liquid medium is preferably carried out by heating the liquid medium to a temperature of 100°C or higher.

[0093] It should be noted that, in electrolytic capacitors, Figure 1 In the case of the wound-type electrolytic capacitor 100 shown, the polymer dispersion is impregnated with... Figure 2 After constructing a capacitor element 10 in the form of a wound body as shown, the capacitor element 10 is heated at a specified temperature, thereby forming a conductive polymer layer.

[0094] <(d) Process>

[0095] In step (d), after forming a conductive polymer layer on the surface of at least one of the dielectric layer and the cathode foil and on the spacer, a spacer is disposed between the anode foil and the cathode foil, thereby forming a capacitor element (specifically, a capacitor element comprising the conductive polymer layer). This step is also a step of stacking the anode foil and the cathode foil with the spacer sandwiched between them.

[0096] There are no particular limitations on the method of forming capacitor elements. Capacitor elements can be formed using various well-known methods. Figure 2 A wound body as shown. In Figure 2 In the winding shown, the anode foil, cathode foil, and spacer are stacked radially in the winding.

[0097] A capacitor element can be formed by stacking flat anode foils, flat cathode foils, and flat spacers in one direction. For example, a capacitor element can be formed by stacking multiple anode foils, multiple cathode foils, and multiple spacers in one direction. An electrolytic capacitor containing such a stacked capacitor element is called a stacked electrolytic capacitor. In a typical example of a stack, anode foils and cathode foils are arranged alternately, with spacers disposed between the anode foils and cathode foils.

[0098] <(e) Process>

[0099] There is no particular limitation on the method of filling the voids within a capacitor element with a liquid component. For example, the liquid component can be filled into the voids within the capacitor element by impregnating at least a portion of the capacitor element.

[0100] As described above, by performing steps (a) to (e), a capacitor element comprising a conductive polymer layer and a liquid component is formed. Then, as needed, the capacitor element is encapsulated in an outer casing (housing). Thus, the electrolytic capacitor of the embodiment of this application is manufactured.

[0101] It should be noted that the above description illustrates an example of forming a conductive polymer layer on the surface of at least one of the dielectric layer and the cathode foil and on the spacer before the anode foil and cathode foil are stacked with a spacer between them. However, examples of forming a conductive polymer layer are not limited to this. The conductive polymer layer can be formed after the anode foil and cathode foil are stacked with a spacer between them. For example, a conductive polymer layer can be formed on the surface of at least one of the dielectric layer and the cathode foil, as well as on the spacer, by immersing the wound body, which is formed by stacking the anode foil and cathode foil with a spacer between them, in a polymer dispersion.

[0102] (Postscript)

[0103] Based on the above description, the following technologies were disclosed.

[0104] (Technology 1)

[0105] An electrolytic capacitor comprising a capacitor element and a liquid component,

[0106] The above-mentioned capacitor element includes:

[0107] Anode foil, which has a dielectric layer;

[0108] A cathode foil, which is arranged opposite to the aforementioned dielectric layer;

[0109] A spacer, which is located between the anode foil and the cathode foil; and

[0110] A conductive polymer layer is disposed between the anode foil and the cathode foil and is in contact with the spacer.

[0111] The aforementioned liquid components contain polymeric compounds.

[0112] The aforementioned polymeric compound comprises a first component, wherein the first component has a mass-average molecular weight Mw of 200 or more and 2000 or less, and the polydispersity (Mw / Mn) ratio of the mass-average molecular weight Mw to the number-average molecular weight Mn is 1.35 or less.

[0113] (Technology 2)

[0114] According to the electrolytic capacitor described in Technique 1, the first component mentioned above is polyalkylene glycol.

[0115] (Technology 3)

[0116] According to the electrolytic capacitor described in Technique 1 or 2, the liquid component contains 5% by mass and 30% by mass of the first component.

[0117] (Technology 4)

[0118] According to any one of the techniques 1 to 3, the electrolytic capacitor comprises at least one of a diol compound and a sulfone compound as a solvent, and at least one of a dicarboxylate salt and a dicarboxylate derivative as a solute.

[0119] (Technology 5)

[0120] According to any one of the techniques 1 to 4, the electrolytic capacitor wherein the liquid component comprises a diol compound and a sulfone compound as a solvent.

[0121] The proportion of the diol compound in the above-mentioned liquid components is 10% by mass or more and 60% by mass or less.

[0122] The proportion of the sulfone compound in the above liquid component is 20% by mass or more and 70% by mass or less.

[0123] Preferred embodiments of the present invention have been described, but such disclosure is not intended to be limiting. Various modifications and alterations will be readily apparent to those skilled in the art upon reading the foregoing disclosure. Therefore, the scope of the appended claims should be interpreted as including all modifications and alterations without departing from the true spirit and scope of the invention.

[0124] Example

[0125] The present application will now be described in detail based on the embodiments and comparative examples, but the present application is not limited to the following embodiments.

[0126] (Example 1)

[0127] (A) Preparation of constituent components

[0128] (A-1) Anode foil

[0129] Etching was performed on both surfaces of an aluminum foil (100 μm thick) to roughen them. The roughened surfaces were then chemically converted to form dielectric layers. This yielded an anode foil with dielectric layers formed on both surfaces.

[0130] (A-2) Cathode foil

[0131] Etching was performed on both surfaces of an aluminum foil (50 μm thick) to obtain a cathode foil with roughened surfaces.

[0132] (A-3) Spacer

[0133] As a spacer, a nonwoven fabric (50 μm thick) is prepared. The nonwoven fabric consists of 50% by mass of synthetic fibers (25% by mass of polyester fibers and 25% by mass of aramid fibers) and 50% by mass of cellulose, containing polyacrylamide as a paper strength reinforcing agent. The density of the nonwoven fabric is 0.35 g / cm³. 3 .

[0134] (B) Preparation of polymeric dispersions

[0135] 3,4-ethylenedioxythiophene and poly(4-styrenesulfonic acid) (PSS, mass-average molecular weight Mw 100,000, dopant) were dissolved in ion-exchanged water to prepare a mixed solution. Next, while stirring the mixed solution, oxidants (ferric sulfate (III) and ammonium persulfate) dissolved in ion-exchanged water were added to the mixed solution to carry out a polymerization reaction. After the polymerization reaction, the resulting reaction solution was dialyzed to remove unreacted monomers and excess oxidant. Thus, PSS-doped poly(3,4-ethylenedioxythiophene) (PEDOT / PSS) was obtained as a polymeric dispersion.

[0136] (C) Fabrication of the wound body

[0137] The anode foil, cathode foil, and spacer are each cut to specified planar dimensions. An anode lead connector is attached to the anode foil, and a cathode lead connector is attached to the cathode foil. Next, the anode and cathode foils are wound together with the spacer in between to obtain a wound body. The ends of the outer surface of the wound body are then secured with a winding fixing tape. An anode lead is attached to the end of the anode lead connector, and a cathode lead is attached to the end of the cathode lead connector. The wound body is then subjected to another chemical conversion treatment to form a dielectric layer on the end face of the anode foil. Specifically, in... Figure 2 A dielectric layer is formed on the upper and lower end faces of the winding body as shown.

[0138] (D) Formation of conductive polymer layer

[0139] In a reduced pressure atmosphere (40 kPa), the wound body is immersed in a polymer dispersion contained in a specified container for 5 minutes, and then the wound body is lifted out of the polymer dispersion. Next, the wound body impregnated with the polymer dispersion is dried in a drying oven at 150°C for 20 minutes to form a conductive polymer layer in such a way as to coat at least a portion of the dielectric layer, thus obtaining a capacitor element.

[0140] (E) Infiltration of liquid components

[0141] An electrolyte (liquid composition) containing ethylene glycol (EG), sulfolane (SL), and polyethylene glycol (PEG) in the proportions shown in Table 1 was prepared. The electrolyte had a weight-average molecular weight (Mw) of 300 and a polydispersity (Mw / Mn) of 1.05. The capacitor element was then immersed in the electrolyte for 5 minutes under reduced pressure (40 kPa). This allowed the electrolyte to permeate the capacitor element. It should be noted that the weight-average molecular weight (Mw) and polydispersity (Mw / Mn) were measured according to the methods described in the above-described embodiments. The same applies to the following examples.

[0142] (F) Sealing of capacitor elements

[0143] The capacitor element, impregnated with electrolyte, is sealed to manufacture... Figure 1 An electrolytic capacitor as shown was then produced. A voltage was applied while an aging treatment was performed at 95°C for 90 minutes. This yielded the electrolytic capacitor of Example 1. It should be noted that an elastic material containing butyl rubber as the rubber component was used as the sealing member for sealing the capacitor element. It should be noted that a total of 40 electrolytic capacitors of Example 1 were manufactured. The same number of electrolytic capacitors were manufactured in the following examples.

[0144] (Example 2)

[0145] Except for the use of PEG with a polydispersity (Mw / Mn) of 1.11 in the electrolyte (liquid component), the electrolytic capacitor of Example 2 was obtained by operating in the same manner as in Example 1.

[0146] (Example 3)

[0147] Except for the use of PEG with a polydispersity (Mw / Mn) of 1.23 in the electrolyte (liquid component), the same procedure as in Example 1 was followed to obtain the electrolytic capacitor of Example 3.

[0148] (Example 4)

[0149] Except for the use of PEG with a polydispersity (Mw / Mn) of 1.31 in the electrolyte (liquid component), the same procedure as in Example 1 was followed to obtain the electrolytic capacitor of Example 4.

[0150] (Example 5)

[0151] Except for the use of PEG with a mass-average molecular weight Mw of 200 and a polydispersity (Mw / Mn) of 1.13 in the electrolyte (liquid component), the electrolytic capacitor of Example 5 was obtained by operating in the same manner as in Example 1.

[0152] (Example 6)

[0153] Except for the use of PEG with a mass-average molecular weight Mw of 400 and a polydispersity (Mw / Mn) of 1.14 in the electrolyte (liquid component), the electrolytic capacitor of Example 6 was obtained by operating in the same manner as in Example 1.

[0154] (Example 7)

[0155] Except for the use of PEG with a mass-average molecular weight Mw of 600 and a polydispersity (Mw / Mn) of 1.15 in the electrolyte (liquid component), the electrolytic capacitor of Example 7 was obtained by operating in the same manner as in Example 1.

[0156] (Example 8)

[0157] Except for the use of PEG with a mass-average molecular weight Mw of 1000 and a polydispersity (Mw / Mn) of 1.06 in the electrolyte (liquid component), the electrolytic capacitor of Example 8 was obtained by operating in the same manner as in Example 1.

[0158] (Example 9)

[0159] Except for the use of PEG with a mass-average molecular weight Mw of 1000 and a polydispersity (Mw / Mn) of 1.17 in the electrolyte (liquid component), the same procedure as in Example 1 was followed to obtain the electrolytic capacitor of Example 9.

[0160] (Example 10)

[0161] Except for the use of PEG with a mass-average molecular weight Mw of 1000 and a polydispersity (Mw / Mn) of 1.30 in the electrolyte (liquid component), the electrolytic capacitor of Example 10 was obtained by operating in the same manner as in Example 1.

[0162] (Example 11)

[0163] Except for the use of PEG with a mass-average molecular weight Mw of 2000 and a polydispersity (Mw / Mn) of 1.15 in the electrolyte (liquid component), the electrolytic capacitor of Example 11 was obtained by operating in the same manner as in Example 1.

[0164] (Example 12)

[0165] Except for using a copolymer of ethylene oxide (EO) and propylene oxide (PO) (EO-PO copolymer) with a mass-average molecular weight Mw of 200 and a polydispersity (Mw / Mn) of 1.08 in the electrolyte (liquid component), the electrolytic capacitor of Example 12 was obtained by operating in the same manner as in Example 1. It should be noted that when the total EO-PO copolymer is set to 1 mole, the molar ratio of EO units to PO units is EO:PO = 0.8:0.2.

[0166] (Example 13)

[0167] Except for the use of an EO-PO copolymer (EO:PO = 0.8:0.2) with a mass-average molecular weight Mw of 2000 and a polydispersity (Mw / Mn) of 1.15 in the electrolyte (liquid component), the electrolytic capacitor of Example 13 was obtained by operating in the same manner as in Example 1.

[0168] (Example 14)

[0169] Except for changing the ratio of EG, SL and PEG in the electrolyte (liquid components) as shown in Table 1, the electrolytic capacitor of Example 14 was obtained by operating in the same manner as in Example 3.

[0170] (Example 15)

[0171] Except for changing the ratio of EG, SL and PEG in the electrolyte (liquid components) as shown in Table 1, the electrolytic capacitor of Example 15 was obtained by operating in the same manner as in Example 3.

[0172] (Example 16)

[0173] Except for changing the ratio of EG, SL and PEG in the electrolyte (liquid components) as shown in Table 1, the electrolytic capacitor of Example 16 was obtained by operating in the same manner as in Example 3.

[0174] (Example 17)

[0175] Except for changing the ratio of EG, SL and PEG in the electrolyte (liquid components) as shown in Table 1, the electrolytic capacitor of Example 17 was obtained by operating in the same manner as in Example 3.

[0176] (Example 18)

[0177] Except for the combined use of two types of PEG (PEGa: mass-average molecular weight Mw200, polydispersity (Mw / Mn) 1.13 and PEGb: mass-average molecular weight Mw300, polydispersity (Mw / Mn) 1.23) in the electrolyte (liquid component), the electrolytic capacitor of Example 18 was obtained by operating in the same manner as in Example 1. PEGa and PEGb were mixed in a mass ratio of PEGa:PEGb = 50:50.

[0178] (Example 19)

[0179] Except that PEGc (weight-average molecular weight Mw300, polydispersity (Mw / Mn) 1.23) and PEGd (weight-average molecular weight Mw400, polydispersity (Mw / Mn) 1.14) were combined as two types of PEG, the electrolytic capacitor of Example 19 was obtained by operating in the same manner as in Example 18.

[0180] (Example 20)

[0181] Except that PEGe (weight-average molecular weight Mw400, polydispersity (Mw / Mn) 1.14) and PEGf (weight-average molecular weight Mw600, polydispersity (Mw / Mn) 1.15) were combined as two types of PEG, the electrolytic capacitor of Example 20 was obtained by operating in the same manner as in Example 18.

[0182] (Comparative Example 1)

[0183] Except for using PEG with a mass-average molecular weight Mw of 300 and a polydispersity (Mw / Mn) of 1.42, the same procedure as in Example 1 was followed to obtain the electrolytic capacitor of Comparative Example 1.

[0184] (Comparative Example 2)

[0185] Except that the electrolyte (liquid component) did not contain polymeric compounds such as PEG or EO-PO copolymers, and the ratio of EG and SL was changed as shown in Table 1, the electrolytic capacitor of Comparative Example 2 was obtained by operating in the same manner as in Example 1.

[0186] (Comparative Example 3)

[0187] Except for the use of PEG with a mass-average molecular weight Mw of 4000 and a polydispersity (Mw / Mn) of 1.25 in the electrolyte, the electrolytic capacitor of Comparative Example 3 was obtained by operating in the same manner as in Example 1.

[0188] [Table 1]

[0189]

[0190] <Evaluation>

[0191] Initial electrostatic capacitance

[0192] For each example of 20 electrolytic capacitors, the initial electrostatic capacitance (in μF) was measured at a temperature of 20°C and a frequency of 120 Hz. The initial electrostatic capacitance was measured using an LCR meter. Then, the arithmetic mean of the measured values ​​was calculated to obtain the average initial electrostatic capacitance (average capacitance). In addition, the standard deviation of the initial electrostatic capacitance was calculated for each example of 20 electrolytic capacitors. The results are shown in Table 2 below.

[0193] • Static capacitance after high-temperature load test

[0194] A high-temperature load test was conducted on 20 electrolytic capacitors from each example. The high-temperature load test was performed by applying a rated voltage of 25V to each electrolytic capacitor at 145°C for 1000 hours. The average capacitance (mean capacitance) was calculated for each electrolytic capacitor after the high-temperature load test. Furthermore, the standard deviation of the capacitance was calculated for each of the 20 electrolytic capacitors. The average capacitance and standard deviation were calculated in the same manner as for the initial capacitance described above. The results are shown in Table 2 below.

[0195] [Table 2]

[0196]

[0197] As shown in Table 2, initially, the electrolytic capacitors of both the examples and the comparative examples exhibited high average capacitances of over 300 μF and low standard deviations of up to 1.41. This indicates that there was no significant deviation in electrostatic capacitance among the multiple electrolytic capacitors.

[0198] On the other hand, after the high-temperature load test, the electrolytic capacitors of each embodiment all showed a high average capacitance of over 250 μF, exhibiting a small standard deviation of up to 3.21. However, in the electrolytic capacitor of Comparative Example 1, which contained PEG (polymer compound) with a polydispersity of 1.42, the standard deviation showed a high value of 6.08, and in the electrolytic capacitor of Comparative Example 3, which contained PEG (polymer compound) with a mass-average molecular weight of 4000 Mw, the standard deviation showed a high value of 11.33. That is, it can be seen that after the high-temperature load test, there is a large deviation in the electrostatic capacitance among the multiple electrolytic capacitors. In addition, in the electrolytic capacitor of Comparative Example 2, which does not contain polymer compounds such as PEG or EO-PO copolymer, the average capacitance after the high-temperature load test decreased significantly to 201 μF.

[0199] Industrial availability

[0200] The electrolytic capacitor of this application can be used in applications where it is required to reduce the deviation of electrostatic capacitance.

[0201] Explanation of reference numerals in the attached figures

[0202] 10: Capacitor Components

[0203] 11: Anode foil

[0204] 12: Cathode foil

[0205] 13: Spacer

[0206] 14: Winding and fixing tape

[0207] 100: Electrolytic capacitor

[0208] 101: Bottom shell

[0209] 102: Sealing components

[0210] 103: Seat board

[0211] 104A, 104B: Lead wires

[0212] 105A, 105B: Lead wire connectors.

Claims

1. An electrolytic capacitor comprising a capacitor element and a liquid component, The capacitor element comprises: Anode foil, which has a dielectric layer; A cathode foil, which is arranged opposite the dielectric layer; A spacer, which is located between the anode foil and the cathode foil; as well as A conductive polymer layer is disposed between the anode foil and the cathode foil and is in contact with the spacer. The liquid component contains polymeric compounds. The polymer compound comprises a first component having a mass-average molecular weight Mw of 200 or more and 2000 or less, and a polydispersity Mw / Mn ratio of mass-average molecular weight Mw to number-average molecular weight Mn of 1.35 or less.

2. The electrolytic capacitor according to claim 1, wherein, The first component is polyalkylene glycol.

3. The electrolytic capacitor according to claim 1 or 2, wherein, The liquid component comprises 5% by mass and less than 30% by mass of the first component.

4. The electrolytic capacitor according to claim 1 or 2, wherein, The liquid component comprises at least one of a diol compound and a sulfone compound as a solvent, and at least one of a dicarboxylate salt and a dicarboxylate derivative as a solute.

5. The electrolytic capacitor according to claim 1 or 2, wherein, The liquid component contains diol compounds and sulfone compounds as solvents. The proportion of the diol compound in the liquid component is more than 10% by mass and less than 60% by mass. The proportion of the sulfone compound in the liquid component is more than 20% by mass and less than 70% by mass.

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