Electrolytic capacitors

Abstract

This product provides an electrolytic capacitor that can maintain low ESR even in high-temperature environments. [Solution] An electrolytic capacitor comprising an anode body having a dielectric layer formed on its surface, a cathode body, and a conductive polymer and a liquid component disposed between the anode body and the cathode body, wherein the liquid component comprises an acid component, a base component and an aromatic additive, the acid component comprises an aromatic carboxylic acid and / or an aromatic carboxylic acid derivative, the aromatic carboxylic acid and / or an aromatic carboxylic acid derivative has at least two carboxyl groups and at least one aromatic ring, the content of the base component in the liquid component is 1% by mass or more, the aromatic additive has an electron-withdrawing group and an electron-donating group, and the content of the aromatic additive in the liquid component is 50 parts by mass or more per 100 parts by mass of the conductive polymer.

Description

Technical Field

[0001] The present invention relates to an electrolytic capacitor having a conductive polymer and a liquid component.

Background Art

[0002] As a small, large-capacity, and low-ESR capacitor, an electrolytic capacitor including an anode body having a dielectric layer, a conductive polymer formed so as to cover at least a part of the dielectric layer, and a liquid component is regarded as promising.

[0003] For example, Patent Document 1 teaches an electrolytic capacitor including a conductive polymer and a conductive auxiliary liquid. In Patent Document 1, it is preferable to lower the conductivity of the conductive auxiliary liquid, and the conductive auxiliary liquid contains an organic solvent having a boiling point of 150°C or higher and an aromatic compound having at least one hydroxyl group. The aromatic compound having at least one hydroxyl group is said to have the ability to assist the electron conduction of the conductive polymer and is also described as being able to suppress the deterioration of the conductive polymer by an antioxidant action.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an electrolytic capacitor having a conductive polymer and a liquid component, the liquid component may contain an acid component and a base component. The acid component, for example, has an action of suppressing the deterioration of the conductive polymer, and the base component, for example, has an action of increasing the degree of dissociation of the acid component and enhancing the conductivity of the electrolytic solution, and it is considered that the capacitance of the electrolytic capacitor can be increased.

[0006] On the other hand, in high-temperature environments, such as above 125°C, the acidic components tend to gradually decrease due to esterification reactions. Furthermore, the basic components can accelerate the degradation of conductive polymers. When conductive polymers degrade, it becomes difficult to maintain a low ESR of the electrolytic capacitor. [Means for solving the problem]

[0007] In view of the above, one aspect of the present disclosure relates to an electrolytic capacitor comprising an anode having a dielectric layer formed on its surface, a cathode, and a conductive polymer and a liquid component disposed between the anode and the cathode, wherein the liquid component comprises an acid component, a base component, and an aromatic additive, the acid component comprises an aromatic carboxylic acid and / or an aromatic carboxylic acid derivative, the aromatic carboxylic acid and / or an aromatic carboxylic acid derivative has at least two carboxyl groups and at least one aromatic ring, the content of the base component in the liquid component is 1% by mass or more, the aromatic additive has an electron-withdrawing group and an electron-donating group, and the content of the aromatic additive in the liquid component is 50 parts by mass or more per 100 parts by mass of the conductive polymer. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an electrolytic capacitor that can increase capacitance and maintain low ESR even in high-temperature environments. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view of an electrolytic capacitor according to one embodiment of the present disclosure. [Figure 2] This is a schematic diagram illustrating the configuration of the capacitor element according to the same embodiment. [Modes for carrying out the invention]

[0010] The electrolytic capacitor according to this disclosure comprises an anode having a dielectric layer formed on its surface, a cathode, and a conductive polymer and a liquid component disposed between the anode and the cathode. The liquid component includes an acid component, a basic component, and an aromatic additive. Here, the acid component includes an aromatic carboxylic acid and / or an aromatic carboxylic acid derivative. The aromatic carboxylic acid and / or aromatic carboxylic acid derivative has at least two carboxyl groups and at least one aromatic ring. The content of the basic component in the liquid component is 1% by mass or more. The aromatic additive has an electron-withdrawing group and an electron-donating group. The content of the aromatic additive in the liquid component is 50 parts by mass or more per 100 parts by mass of the conductive polymer.

[0011] Conductive polymers are, for example, π-conjugated conductive polymers, and are usually doped with dopants to improve conductivity. The presence of an acidic component in the liquid component is thought to suppress dopant dedoping, thereby preventing degradation of the conductive polymer or a decrease in conductivity.

[0012] On the other hand, basic components are thought to play a role in increasing the degree of dissociation of acidic components and thereby increasing the conductivity of the liquid component. However, basic components also have the effect of promoting the dedoping of dopants from conductive polymers. Therefore, it is desirable to control the composition of the liquid component so that the basic component does not become excessive.

[0013] Among acidic components, aromatic carboxylic acids and aromatic carboxylic acid derivatives (hereinafter, aromatic carboxylic acids and aromatic carboxylic acid derivatives are collectively referred to as aromatic carboxylic acids) are relatively stable. In particular, aromatic carboxylic acids having at least two carboxyl groups and at least one aromatic ring are relatively stable against esterification reactions. From the viewpoint of suppressing the increase in viscosity of the liquid component, it is desirable for aromatic carboxylic acids to have one or two C6 benzene rings and / or C10 naphthyl rings.

[0014] As the aromatic carboxylic acid, a more stable divalent to tetravalent carboxylic acid is preferred, and it is desirable that two or more carboxyl groups are directly bonded to each other at the ortho position of the aromatic ring. Specifically, phthalic acid, pyromellitic acid, etc. can be used as the aromatic carboxylic acid. Among these, phthalic acid is preferred, and o-phthalic acid is particularly preferred.

[0015] As aromatic carboxylic acid derivatives, condensates of carboxylic acids and inorganic acids (e.g., boric acid, phosphoric acid, etc.) are stable and preferred, and for example, condensates of carboxylic acids and boric acid are preferred. Specifically, borodisalicylic acid, borodiglycolic acid, borodisuoic acid, etc. can be used.

[0016] The content of aromatic carboxylic acids in the liquid component may be, for example, 1.0% by mass or more, preferably 2.0% by mass or more, 40% by mass or less, and preferably 20% by mass or less.

[0017] The acidic component content in the liquid component is, for example, 100 parts by mass or more, preferably 130 parts by mass or more, for example 700 parts by mass or less, and preferably 500 parts by mass or less, per 100 parts by mass of the basic component.

[0018] The basic component is preferably at least one selected from the group consisting of primary amines, secondary amines, and tertiary amines. Using an amine component (especially primary to tertiary amines) enhances the effect of stabilizing the ESR over the long term. Quaternary amines may also be used, but from the viewpoint of suppressing side reactions as much as possible, primary to tertiary amines that exhibit moderate basicity are preferable. As each amine, aliphatic amines, aromatic amines, heterocyclic amines, etc., can be used, but aliphatic amines with a molecular weight of 72 to 102 are preferred due to their high degree of dissociation.

[0019] Examples of the primary to tertiary amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, N,N - diisopropylethylamine, tetramethylethylenediamine, hexamethylenediamine, spermidine, spermine, amantadine, aniline, phenethylamine, toluidine, pyrrolidine, piperidine, piperazine, morpholine, imidazole, pyridine, pyridazine, pyrimidine, pyrazine, 4 - dimethylaminopyridine, and the like. These may be used alone or in combination of two or more. Among these, tertiary amines such as triethylamine and monoethyldimethylamine are particularly preferred.

[0020] At least a part of the aromatic carboxylic acid may be derived from a salt with a base component. That is, as the acid component and the base component, a salt of an aromatic carboxylic acid and a base component may be included in the liquid component.

[0021] Even for the relatively stable aromatic carboxylic acids as described above, in a high - temperature environment of about 125 °C, the esterification reaction gradually proceeds. As a result, the acid component gradually decreases. On the other hand, the base component contained in the liquid component does not decrease in the esterification reaction. Moreover, in order to sufficiently increase the conductivity and capacitance of the liquid component, it is desirable to make the content of the base component contained in the liquid component as high as 1% by mass or more. The content of the base component contained in the liquid component is more preferably 1.4% by mass or more, and even more preferably 1.8% by mass or more. Therefore, when an aromatic additive is not used, there is a concern that the dedoping of the dopant from the conductive polymer is promoted.

[0022] In contrast, when an aromatic additive is used, even in a high-temperature environment, dedoping of the dopant from the conductive polymer is suppressed. Since the aromatic additive has an electron-withdrawing group and an electron-donating group, the electron-donating group can exhibit acidity. On the other hand, the electron-withdrawing group has an effect of stabilizing the acidic electron-donating group. As a result, when a sufficient amount of the aromatic additive is present with respect to the conductive polymer, it is considered that the promoting effect of dedoping by the base component is alleviated. Moreover, the electron-donating group of the aromatic additive is relatively stable against the esterification reaction. Therefore, it is considered that the amount of the aromatic additive is difficult to decrease, and the effect of suppressing dedoping of the dopant from the conductive polymer even in a high-temperature environment (hereinafter referred to as the dedoping suppression effect) continues.

[0023] However, when the content of the base component contained in the liquid component exceeds, for example, 10.0% by mass, the dedoping suppression effect may not act effectively. Therefore, it is desirable that the content of the base component contained in the liquid component be 10.0% by mass or less.

[0024] Here, a sufficient amount with respect to the conductive polymer means that the content of the aromatic additive contained in the liquid component is 50 parts by mass or more with respect to 100 parts by mass of the conductive polymer. When the content of the aromatic compound contained in the liquid component is less than 50 parts by mass with respect to 100 parts by mass of the conductive polymer, an effective dedoping suppression effect cannot be obtained. Although the aromatic additive is stable and exhibits acidity, since its acidity is weak, it is necessary to include a sufficient amount in the liquid component with respect to the mass of the conductive polymer. The content of the aromatic additive contained in the liquid component is preferably 100 parts by mass or more, more preferably 150 parts by mass or more, with respect to 100 parts by mass of the conductive polymer. However, when the aromatic additive becomes excessive, the conductivity of the liquid component decreases, and the capacitance characteristics at low temperature and low frequency deteriorate. Therefore, the amount of the aromatic additive is preferably 1000 parts by mass or less, or 800 parts by mass or less, with respect to 100 parts by mass of the conductive polymer.

[0025] The content of the aromatic additive contained in the liquid component may be, for example, 1% by mass or more, and preferably 2% by mass or more.

[0026] In aromatic additives, the number of electron-withdrawing groups directly bonded to the aromatic ring may be, for example, 1 to 3. Examples of electron-withdrawing groups include nitro groups, carboxyl groups, phenyl groups, acyl groups, tosyl groups, keto groups, cyano groups, methylsulfonyl groups, and halogen groups. When an aromatic additive has two or more electron-withdrawing groups, these two or more groups may be the same or different.

[0027] In aromatic additives, the number of electron-donating groups directly bonded to the aromatic ring may be, for example, 1 to 3. Examples of electron-donating groups include hydroxyl groups, amino groups, alkyl groups, alkoxy groups, and ester groups. If an aromatic additive has two or more electron-donating groups, these two or more groups may be the same or different.

[0028] Specific examples of aromatic additives include, but are not limited to, (p-,m-,o-)nitrophenol, dinitrophenol, trinitrophenolic acid, (p-,m-,o-)hydroxybenzenecarboxylic acid, dihydroxybenzenecarboxylic acid, (p-,m-,o-)acetylphenol, (p-,m-,o-)benzoylphenol, and (p-,m-,o-)methylsulfonylphenol. Aromatic additives may be used individually or in combination of two or more.

[0029] The solvent mixed with the acidic component, basic component, and aromatic additive is not particularly limited, but it is desirable to use at least a polymeric solvent in order to improve the heat resistance of the electrolytic capacitor. Examples of polymeric solvents include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyglycerins, or ethers in which the ends of these are alkylated. In particular, the molecular weight of polyethylene glycol may be, for example, 190 to 400, or 200 to 300.

[0030] The content of polymeric solvents in the liquid component may be, for example, 0.5% by mass or more, 1% by mass or more, preferably 20% by mass or more, and 90% by mass or less.

[0031] The liquid component may include low molecular weight glycol compounds such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol, or glycerin, as a solvent. Low molecular weight glycol compounds or glycerin are thought to enhance the orientation of conductive polymers, improve conductivity, and reduce ESR. Among these, ethylene glycol is preferred because it has relatively low viscosity, high thermal conductivity, and excellent heat dissipation properties.

[0032] The ethylene glycol content in the liquid component may be, for example, 3.0% by mass or more, preferably 10% by mass or more, and may be 90% by mass or less.

[0033] The liquid component may include, as a solvent, other than the polymer solvents and low molecular weight glycol compounds mentioned above, for example, sulfone compounds, lactone compounds, and carbonate compounds. Sulfone compounds may include sulfolane, dimethyl sulfoxide, and diethyl sulfoxide. Lactone compounds may include γ-butyrolactone and γ-valerolactone. Carbonate compounds may include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate (FEC). The solvent may be used alone or in combination of two or more.

[0034] The liquid component may contain aromatic compounds having only electron-donating groups, from the viewpoint of maintaining a low ESR of the electrolytic capacitor over a longer period of time. Examples of such aromatic compounds include phenol, dibutylhydroxytoluene, cresol, methoxyphenol, eugenol, guaiacol, thymol, catechol, and pyrogallol. Among these, divalent to tetravalent phenolic compounds having 2 to 4 phenolic hydroxyl groups are preferred. Specifically, catechol and / or pyrogallol can be used.

[0035] The content of aromatic compounds having only electron-donating groups in the liquid component may be, for example, 0.1 to 30% by mass, or 2 to 25% by mass.

[0036] The pH of the liquid component is preferably 6 or less, more preferably 4 or less, and even more preferably 3.8 or less or 3.6 or less. By setting the pH of the liquid component to 4 or less, the degradation of the conductive polymer is further significantly suppressed.

[0037] The conductive polymer may be synthesized by applying a solution containing monomers, dopants, and oxidizing agents to a dielectric layer and allowing it to undergo chemical or electrolytic polymerization in situ. Alternatively, a pre-synthesized conductive polymer may be applied to the dielectric layer. In this case, for example, a liquid polymer dispersion containing a conductive polymer and a polymer dopant may be impregnated into the dielectric layer to form a conductive polymer film that covers at least a portion of the dielectric layer.

[0038] Preferred conductive polymers include polypyrrole, polythiophene, and polyaniline. These may be used individually, in combination of two or more, or as copolymers of two or more monomers. In this specification, polypyrrole, polythiophene, and polyaniline refer to polymers that have polypyrrole, polythiophene, and polyaniline as their basic skeletons, respectively. Therefore, derivatives of polypyrrole, polythiophene, and polyaniline may also be included. For example, polythiophene includes poly(3,4-ethylenedioxythiophene) (PEDOT). The weight-average molecular weight of the conductive polymer is not particularly limited, but is, for example, 1,000 to 1,000,000.

[0039] From the viewpoint of suppressing dedoping from conductive polymers, it is desirable to use polymer dopants. Examples of polymer dopants include anions such as polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polyacrylic acid. These may be used individually or in combination of two or more. Furthermore, these may be homopolymers or copolymers of two or more monomers. Among these, polystyrene sulfonic acid (PSS) is preferred. The weight-average molecular weight of the polymer dopant is not particularly limited, but it is preferably, for example, 1,000 to 1,000,000, as it facilitates the formation of a homogeneous solid electrolyte layer.

[0040] The present invention will be described more specifically below based on embodiments. However, the following embodiments are not intended to limit the present invention.

[0041] Figure 1 is a schematic cross-sectional view of an electrolytic capacitor according to this embodiment, and Figure 2 is a schematic diagram showing a portion of the capacitor element related to the electrolytic capacitor unfolded.

[0042] The electrolytic capacitor shown in Figure 1 comprises a capacitor element 10, a bottomed case 11 housing the capacitor element 10, a sealing member 12 closing the opening of the bottomed case 11, a base plate 13 covering the sealing member 12, lead wires 14A and 14B extending from the sealing member 12 and passing through the base plate 13, lead tabs 15A and 15B connecting the lead wires to the electrodes of the capacitor element 10, and a liquid component (not shown). The open end of the bottomed case 11 is curled so as to be crimped to the sealing member 12.

[0043] The capacitor element 10 is manufactured from a wound body as shown in Figure 2. The wound body is a semi-finished product of the capacitor element 10, in which a conductive polymer is not placed between the anode 21, which has a dielectric layer on its surface, and the cathode 22. The wound body is made by winding the anode 21, which is connected to a lead tab 15A, and the cathode 22, which is connected to a lead tab 15B, with a separator 23 in between. The outermost circumference of the wound body is fixed with a winding stopper tape 24. Note that Figure 2 shows a partially unfolded state of the wound body before the outermost circumference is fixed.

[0044] The anode body 21 comprises a metal foil with a roughened surface, and a dielectric layer is formed on the roughened surface. A capacitor element 10 is formed by attaching a conductive polymer to at least a portion of the surface of the dielectric layer. The capacitor element 10 is housed in an outer casing along with a liquid component (not shown).

[0045] The following describes an example of a manufacturing method for electrolytic capacitors. (i) Steps to prepare an anode 21 and a cathode 22 having a dielectric layer. The anode 21 and cathode 22 are made from metal foil formed from valve metal. In the case of the anode 21, the surface of the metal foil is roughened by etching or the like, creating multiple irregularities on the surface of the metal foil. Next, a dielectric layer is formed on the roughened surface of the metal foil by chemical conversion treatment or the like. The surface of the cathode 22 may also be roughened as needed.

[0046] (ii) Preparation of the coiled body A winding body is prepared by winding an anode 21 and a cathode 22 with a separator 23 in between. The separator 23 may be a nonwoven fabric mainly composed of synthetic cellulose or the like. A winding stopper tape 24 is placed on the outer surface of the cathode 22, which is located in the outermost layer of the winding body, to fix the end of the cathode 22. If necessary, the winding body is further treated with chemical conversion.

[0047] (iii) Steps to form the capacitor element 10 For example, a liquid polymer dispersion is impregnated into a dielectric layer to form a conductive polymer film that covers at least a portion of the dielectric layer. This yields a capacitor element 10 in which a conductive polymer is positioned between the anode 21 and the cathode 22. The step of applying the polymer dispersion to the surface of the dielectric layer may be repeated two or more times. After that, the capacitor element 10 can be impregnated with a liquid component. This yields an electrolytic capacitor comprising a conductive polymer and a liquid component.

[0048] (iv) Process of sealing the capacitor element The capacitor element 10 is housed in the bottomed case 11 along with its liquid component so that the lead wires 14A and 14B are positioned on the opening side of the bottomed case 11. Next, the opening of the bottomed case 11 is closed with a sealing member 12 through which each lead wire passes, the open ends are crimped to the sealing member 12 and curled, and a base plate 13 is placed on the curled portion to complete the electrolytic capacitor as shown in Figure 1.

[0049] Although the above embodiments described wound electrolytic capacitors, the scope of application of the present invention is not limited to those described above. It can also be applied to other electrolytic capacitors, such as chip-type electrolytic capacitors that use a sintered metal body as the anode, and multilayer electrolytic capacitors that use a metal plate as the anode.

[0050] [Examples] The present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0051] In the following example, a wound electrolytic capacitor (Φ8.0mm × L(length)12.0mm) with a rated voltage of 100V and a rated capacitance of 15μF was fabricated. The specific manufacturing method of the electrolytic capacitor is described below.

[0052] (Preparation of the anode) A 100 μm thick aluminum foil was etched to roughen its surface. Subsequently, a dielectric layer was formed on the surface of the aluminum foil by a chemical conversion treatment. This treatment involved immersing the aluminum foil in an ammonium adipate solution and applying a voltage of 180 V. Afterward, the aluminum foil was cut to prepare the anode.

[0053] (Preparation of the cathode) A 50 μm thick aluminum foil was etched to roughen its surface. The aluminum foil was then prepared as a cathode.

[0054] (Preparation of coiled bodies) Anode lead tabs and cathode lead tabs were connected to the anode and cathode bodies, and the anode and cathode bodies were wound together with separators, incorporating the lead tabs. Anode lead wires and cathode lead wires were connected to the ends of each lead tab protruding from the wound body. The fabricated wound body was subjected to another chemical conversion treatment to form a dielectric layer on the cut ends of the anode bodies. Next, the ends of the outer surface of the wound body were secured with winding tape to create the wound body.

[0055] (Preparation of polymer dispersions) A mixed solution was prepared by dissolving 3,4-ethylenedioxythiophene and polystyrene sulfonic acid (PSS, weight-average molecular weight 100,000), a high-molecular-weight dopant, in deionized water. Iron(III) sulfate (oxidizing agent) dissolved in deionized water was added to the mixed solution while stirring, and a polymerization reaction was carried out. After the reaction, the resulting reaction solution was dialyzed to remove unreacted monomers and excess oxidizing agent, yielding a high-molecular-weight dispersion containing polyethylenedioxythiophene (PEDOT / PSS) doped with approximately 5% by mass of PSS.

[0056] (Formation of a solid electrolyte layer) The wound body was immersed in a polymer dispersion contained in a predetermined container for 5 minutes in a reduced-pressure atmosphere (40 kPa), and then the wound body was removed from the polymer dispersion. Next, the wound body impregnated with the polymer dispersion was dried in a drying oven at 150°C for 20 minutes to form a solid electrolyte layer consisting of a conductive polymer layer that covers at least a portion of the dielectric layer.

[0057] (Impregnation with liquid components) Liquid components containing acidic components, basic components, aromatic additives, aromatic compounds having only electron-donating groups, and various solvents were prepared in the compositions shown in Tables 1 to 4, and the wound body was immersed in the liquid components for 5 minutes under reduced pressure (40 kPa).

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] [Table 4]

[0062] (Sealing of capacitor elements) Capacitor elements impregnated with liquid components were sealed to complete electrolytic capacitors (A1-A19 and B1-B6) as shown in Figure 1. Subsequently, an aging process was performed at 130°C for 2 hours while applying the rated voltage. Electrolytic capacitors A1-A19 correspond to Examples 1-19, respectively, and electrolytic capacitors B1-B6 correspond to Comparative Examples 1-6.

[0063] [evaluation] The capacitance and initial ESR of the obtained electrolytic capacitors were measured.

[0064] Next, to evaluate long-term reliability, the device was held at 145°C for 2000 hours while applying the rated voltage, and the rate of increase in ESR (ΔESR) was confirmed. ΔESR is expressed as the ratio (X / X0) of the ESR (X) after holding at 145°C to the initial value (X0). The evaluation results are shown in Table 5.

[0065] [Table 5] [Industrial applicability]

[0066] The present invention is useful in electrolytic capacitors having a conductive polymer and a liquid component. [Explanation of Symbols]

[0067] 10: Capacitor element, 11: Bottomed case, 12: Sealing material, 13: Base plate, 14A, 14B: Lead wires, 15A, 15B: Lead tabs, 21: Anode, 22: Cathode, 23: Separator, 24: Winding tape

Claims

1. an anode body with a dielectric layer formed on its surface, Cathode body and, The anode and cathode are disposed between the conductive polymer and the liquid component, The aforementioned liquid component comprises an acid component, a basic component, and an aromatic additive. The acid component comprises an aromatic carboxylic acid and / or an aromatic carboxylic acid derivative. The amount of the base component contained in the liquid component is 1% by mass or more. The aforementioned aromatic additive has an electron-withdrawing group and an electron-donating group, An electrolytic capacitor in which the amount of the aromatic additive contained in the liquid component is 50 parts by mass or more per 100 parts by mass of the conductive polymer.

2. The electrolytic capacitor according to claim 1, wherein the content of the aromatic additive contained in the liquid component is 1% by mass or more.

3. The electrolytic capacitor according to claim 1 or 2, wherein the liquid component comprises a polymer-based solvent.

4. The electrolytic capacitor according to claim 3, wherein the polymer solvent is at least one selected from the group consisting of polyethylene glycol, polypropylene glycol and other polyalkylene glycols and polyglycerin.

5. The electrolytic capacitor according to claim 3 or 4, wherein the content of the polymer-based solvent contained in the liquid component is 0.5% by mass or more.

6. The electrolytic capacitor according to any one of claims 1 to 5, wherein the electron-withdrawing group is at least one selected from the group consisting of a nitro group, a carboxyl group, a phenyl group, an acyl group, a tosyl group, a keto group, a cyano group, a methylsulfonyl group, and a halogen group.

7. The electrolytic capacitor according to any one of claims 1 to 6, wherein the electron-donating group is at least one selected from the group consisting of a hydroxyl group, an amino group, an alkyl group, an alkoxy group, and an ester group.

8. The electrolytic capacitor according to any one of claims 1 to 7, wherein the aromatic additive is at least one selected from the group consisting of (p-,m-,o-)nitrophenol, dinitrophenol, trinitrophenol, (p-,m-,o-)hydroxybenzenecarboxylic acid, dihydroxybenzenecarboxylic acid, (p-,m-,o-)acetylphenol, (p-,m-,o-)benzoylphenol, and (p-,m-,o-)methylsulfonylphenol.

9. The electrolytic capacitor according to any one of claims 1 to 8, wherein the amount of the aromatic additive contained in the liquid component is 50 parts by mass or more per 100 parts by mass of the conductive polymer, except in the case where the amount of the aromatic additive is less than the amount of the basic component.

10. The electrolytic capacitor according to any one of claims 1 to 9, wherein the content of the base component in the liquid component is 1.8% by mass or more.

11. The electrolytic capacitor according to any one of claims 1 to 10, wherein the content of the base component contained in the liquid component is 10% by mass or less.

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