Electrolytic capacitors and capacitor elements

Abstract

This electrolytic capacitor comprises at least one capacitor element. The capacitor element comprises: an anode body; a dielectric layer formed on the surface of the anode body; a solid electrolyte layer that covers at least a part of the solid electrolyte layer; and a first layer that is in contact with the solid electrolyte layer and that covers at least a part of the solid electrolyte layer. The first layer constitutes at least a part of a cathode extraction layer. The electrode potential Ps of the solid electrolyte layer is higher than the electrode potential P1 of the first layer. Provided is an electrolytic capacitor for which ESR is suppressed.

Description

[Technical field]

[0001] The present disclosure relates to a capacitor element having a solid electrolyte layer containing a conductive polymer, and an electrolytic capacitor including the same. [Background technology]

[0002] As a small-sized, large-capacity, low-ESR (equivalent series resistance) capacitor, an electrolytic capacitor having a capacitor element with a solid electrolyte layer containing a conductive polymer is considered to be promising. The capacitor element includes, for example, an anode body, a dielectric layer formed on at least a part of the surface of the anode body, a solid electrolyte layer covering at least a part of the dielectric layer, and a cathode lead layer covering at least a part of the solid electrolyte layer. An electrolytic capacitor having a solid electrolyte layer is also called a solid electrolytic capacitor.

[0003] Patent Document 1 proposes using a conductive polymer complexed with an ionic polymer in a solid electrolytic capacitor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-281410 A Summary of the Invention

[0005] An electrolytic capacitor according to one aspect of the present disclosure includes ,Ko a capacitor element including an anode body, a dielectric layer formed on a surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, and a first layer in contact with the solid electrolyte layer and covering at least a portion of the solid electrolyte layer, the first layer constituting at least a portion of a cathode extraction layer, and an electrode potential P s is higher than the electrode potential P1 of the first layer.

[0006] According to another aspect of the present disclosure Capacitor Elementanode body, a dielectric layer formed on a surface of the anode body, and a solid electrolyte layer covering at least a portion of the dielectric layer; In contact with the solid electrolyte layer a first layer that covers at least a portion of the solid electrolyte layer, the first layer constituting at least a portion of the cathode extraction layer, and an electrode potential P s is higher than the electrode potential P1 of the first layer.

[0007] It is possible to provide an electrolytic capacitor in which the increase in ESR is suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view of an electrolytic capacitor according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Prior to describing the embodiments, problems in the prior art will be briefly described below.

[0010] In electrolytic capacitors with a solid electrolyte layer, the conductive polymer contained in the solid electrolyte layer gradually oxidizes and deteriorates, causing an increase in ESR. When the conductive polymer oxidizes and deteriorates, the resistance of the solid electrolyte layer increases and the capacitance decreases. When this increase in ESR or decrease in capacitance occurs, the reliability of the electrolytic capacitor decreases. In particular, when an electrolytic capacitor is exposed to a high-temperature environment for a long period of time, the oxidative deterioration of the conductive polymer becomes significant, making it more likely that the ESR will increase or the capacitance will decrease.

[0011] In general, when the electrode potential of a metal is high, it is less likely to be oxidized than when it is low. When a member containing a first metal is in contact with a member containing a second metal that has a lower electrode potential than the first metal, and a component responsible for electron transfer, such as water molecules, is present, only the second metal is oxidized, forming a local battery.

[0012] In the case of electrolytic capacitors, the intrusion of moisture into the electrolytic capacitor can cause the oxidative degradation of the conductive polymer. It has been revealed that one of the causes of this oxidative degradation is that the electrode potential of the solid electrolyte layer is lower than the electrode potential of the cathode extraction layer that is in contact with the solid electrolyte layer, causing the oxidation of the conductive polymer to proceed preferentially. The oxidative degradation of conductive polymers is particularly noticeable in high temperature environments.

[0013] In view of this new finding, in the electrolytic capacitor or capacitor element of the present disclosure, the electrode potential P s of, In contact with the solid electrolyte layer The electrode potential is set higher than the electrode potential P1 of the first layer which covers at least a portion of the solid electrolyte layer and constitutes at least a portion of the cathode extraction layer.

[0014] Electrode potential P of the solid electrolyte layer s is made higher than the electrode potential P1 of the first layer, the oxidation of the conductive polymer contained in the solid electrolyte layer is suppressed, and the deterioration of the solid electrolyte layer is suppressed. This suppresses the increase in ESR. In addition, the increase in resistance due to the deterioration of the solid electrolyte layer is suppressed, and the decrease in capacitance is also suppressed. This improves the reliability of the electrolytic capacitor.

[0015] Electrode potential P of the solid electrolyte layer s can be adjusted by, for example, selecting or adjusting the type of conductive polymer, the type of dopant, the ratio of the dopants, the potential (hereinafter referred to as polymerization potential) and current applied when forming the conductive polymer by polymerization. When forming a solid electrolyte layer by generating a conductive polymer on a flat surface, the electrode potential P s There is a certain degree of correlation between the polymerization potential and the electrode potential. However, in reality, in an electrolytic capacitor, a dielectric layer is formed along the inner wall surface of the holes and depressions (pits) on the surface of the anode body, at least the surface layer of which is porous, and a solid electrolyte layer is also formed along the inner wall surface of the holes and pits so as to cover this dielectric layer. Therefore, the electrode potential P of the solid electrolyte layer in an electrolytic capacitor s does not necessarily correlate with the polymerization potential.

[0016] In addition, the electrode potential P s and P1 is a silver / silver chloride electrode (Ag / Ag + ) is the value measured using a reference electrode.

[0017] Hereinafter, the electrolytic capacitor and the manufacturing method thereof according to the present disclosure will be described in more detail with reference to the drawings as necessary.

[0018] [Electrolytic capacitor] The electrolytic capacitor includes one or more capacitor elements. At least one of the capacitor elements included in the electrolytic capacitor has a P s If an electrolytic capacitor contains two or more capacitor elements, P1 must be greater than 50% of the capacitor elements. s It is preferable that P1 is greater than 75% of the capacitor elements. s It is more preferable that P > P1, and P s It is even more preferable that P1.

[0019] (Capacitor element) (Anode body) The anode body may contain a valve metal, an alloy containing a valve metal, a compound containing a valve metal, etc. These materials may be used alone or in combination of two or more. For example, aluminum, tantalum, niobium, and titanium are preferably used as the valve metal. An anode body having a porous surface may be obtained, for example, by roughening the surface of a base material (foil-shaped or plate-shaped base material, etc.) containing a valve metal. The roughening may be performed, for example, by etching. The anode body may also be a molded body of particles containing a valve metal or a sintered body thereof. The sintered body has a porous structure.

[0020] (Dielectric layer) The dielectric layer is an insulating layer that functions as a dielectric and is formed so as to cover at least a part of the surface of the anode body. The dielectric layer is formed by anodizing the valve metal on the surface of the anode body by chemical conversion treatment or the like. The dielectric layer may be formed so as to cover at least a part of the anode body. The dielectric layer is usually formed on the surface of the anode body. Since the dielectric layer is formed on the porous surface of the anode body, it is formed along the inner wall surface of the holes or pits on the surface of the anode body.

[0021] The dielectric layer contains an oxide of the valve metal. For example, when tantalum is used as the valve metal, the dielectric layer contains Ta2O5, and when aluminum is used as the valve metal, the dielectric layer contains Al2O3. However, the dielectric layer is not limited to this and may be any material that functions as a dielectric.

[0022] (Solid electrolyte layer) The solid electrolyte layer is formed on the surface of the anode body via the dielectric layer so as to cover the dielectric layer. The solid electrolyte layer does not necessarily have to cover the entire dielectric layer (the entire surface), but may be formed so as to cover at least a part of the dielectric layer. The solid electrolyte layer constitutes at least a part of the cathode body in the electrolytic capacitor. The cathode body usually includes a solid electrolyte layer and a cathode extraction layer.

[0023] In the electrolytic capacitor or capacitor element of the present disclosure, the electrode potential P s is set to be higher than the electrode potential P1 of the first layer included in the cathode extraction layer. s The difference between P and P1 is, for example, 0.02 V or more, preferably 0.05 V or more, and more preferably 0.1 V or more. s When the difference between P1 and P2 is within such a range, the oxidative deterioration of the solid electrolyte layer can be further suppressed.

[0024] Electrode potential P of the solid electrolyte layer s For example, it may be greater than 0.2 V, may be 0.22 V or more, or may be 0.25 V or more. Depending on the electrode potential P1 of the first layer, P sBy setting P in this range, it becomes easier to suppress the oxidative deterioration of the solid electrolyte layer. s The upper limit is not particularly limited, but may be, for example, 0.5 V or less.

[0025] Electrode potential P of the solid electrolyte layer s The solid electrolyte layer was exposed by immersing the sample in a 1.5 wt% aqueous solution of p-toluenesulfonic acid. + ) as a reference electrode. A sample can be prepared by cutting the capacitor element with a microtome or the like until the solid electrolyte layer is exposed. The electrode potential P1 of the first layer can also be measured by the electrode potential P of the solid electrolyte layer. s The measurement can be performed using a sample with the first layer exposed, similar to the case of 1. The sample can be prepared by cutting the capacitor element, if necessary, with a microtome or the like until the first layer is exposed.

[0026] The solid electrolyte layer includes a conductive polymer and may further include at least one of a dopant and an additive, as necessary.

[0027] The conductive polymer may be a known one used in electrolytic capacitors, such as a π-conjugated conductive polymer. The conductive polymer may be, for example, a polymer having a basic skeleton of polypyrrole, polythiophene, polyaniline, polyfuran, polyacetylene, polyphenylene, polyphenylenevinylene, polyacene, or polythiophenevinylene. Of these, a polymer having a basic skeleton of polypyrrole, polythiophene, or polyaniline is preferred. The above polymers include homopolymers, copolymers of two or more monomers, and derivatives thereof (such as substitutes having a substituent). For example, polythiophenes include poly(3,4-ethylenedioxythiophene).

[0028] The conductive polymer may be used alone or in combination of two or more kinds.

[0029] The weight average molecular weight (Mw) of the conductive polymer is not particularly limited, but is, for example, 1,000 or more and 1,000,000 or less.

[0030] In this specification, the weight average molecular weight (Mw) is a value calculated as polystyrene measured by gel permeation chromatography (GPC). GPC is usually measured using a polystyrene gel column and water / methanol (volume ratio 8 / 2) as the mobile phase.

[0031] The solid electrolyte layer may further include a dopant, for example, at least one selected from the group consisting of an anion and a polyanion.

[0032] Examples of the anion include, but are not limited to, sulfate ion, nitrate ion, phosphate ion, borate ion, organic sulfonate ion, carboxylate ion, etc. Examples of the dopant that generates the sulfonate ion include p-toluenesulfonic acid and naphthalenesulfonic acid.

[0033] Examples of polyanions include polymeric polysulfonic acid and polymeric polycarboxylic acid. Examples of polymeric polysulfonic acid include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, and polymethacrylic sulfonic acid. Examples of polymeric polycarboxylic acid include polyacrylic acid and polymethacrylic acid. Examples of polyanions include polyester sulfonic acid and phenol sulfonic acid novolac resin. However, polyanions are not limited to these.

[0034] The anion and the polyanion may each be contained in the solid electrolyte layer in the form of a salt. In the solid electrolyte layer, the anion and the polyanion may each form a conductive polymer complex together with the conductive polymer.

[0035] The amount of the dopant contained in the solid electrolyte layer is, for example, 10 to 1000 parts by mass, and may be 20 to 500 parts by mass, or 50 to 200 parts by mass, relative to 100 parts by mass of the conductive polymer.

[0036] The solid electrolyte layer may be a single layer or may be composed of multiple layers. When the solid electrolyte layer is composed of multiple layers, the conductive polymers contained in each layer may be the same or different. Furthermore, the dopants contained in each layer may be the same or different.

[0037] The solid electrolyte layer may further contain known additives and known conductive materials other than the conductive polymer, as necessary, such as at least one selected from the group consisting of conductive inorganic materials such as manganese dioxide and TCNQ complex salts.

[0038] A layer for enhancing adhesion may be interposed between the dielectric layer and the solid electrolyte layer.

[0039] The solid electrolyte layer is formed, for example, by using a treatment liquid containing a precursor of a conductive polymer to polymerize the precursor on the dielectric layer. The polymerization can be performed by at least one of chemical polymerization and electrolytic polymerization. Examples of the precursor of the conductive polymer include a monomer, an oligomer, and a prepolymer. The solid electrolyte layer may be formed by attaching a treatment liquid (for example, a dispersion liquid or a solution) containing the conductive polymer to the dielectric layer and then drying the applied liquid. Examples of the dispersion medium (or solvent) include water, an organic solvent, or a mixture thereof. The treatment liquid may further include other components such as a dopant.

[0040] When a treatment liquid containing a precursor of a conductive polymer is used, an oxidizing agent is used to polymerize the precursor. The oxidizing agent may be included in the treatment liquid as an additive. The oxidizing agent may be applied to the anode body before or after the treatment liquid is brought into contact with the anode body on which the dielectric layer is formed. Examples of such oxidizing agents include sulfates, sulfonic acids, or salts thereof. The oxidizing agents may be used alone or in combination of two or more. Examples of sulfates include salts of sulfuric acid such as ferric sulfate and sodium persulfate, and salts of sulfates such as persulfate and metals. Examples of metals constituting the salts include alkali metals (sodium, potassium, etc.), iron, copper, chromium, zinc, etc. The sulfonic acid or salts thereof function as a dopant in addition to functioning as an oxidizing agent. Examples of sulfonic acids or salts thereof include low molecular weight sulfonic acids or salts thereof exemplified for dopants.

[0041] The process of forming a solid electrolyte layer by immersion in a treatment liquid and polymerization (or drying) may be carried out once or may be repeated several times. In each process, the conditions such as the composition and viscosity of the treatment liquid may be the same or at least one of the conditions may be changed.

[0042] Electrode potential P of the solid electrolyte layer s When the solid electrolyte layer is formed using chemical polymerization or a treatment solution containing a conductive polymer, the electrode potential P can be adjusted by selecting the type of conductive polymer and the type of dopant, or adjusting the amount or concentration of the dopant. When the solid electrolyte layer is formed by electrolytic polymerization, the electrode potential P can be adjusted by selecting the type of conductive polymer and the type of dopant, adjusting the amount or concentration of the dopant, or adjusting the polymerization potential. s can be adjusted.

[0043] (Cathode extraction layer) The cathode extraction layer may include at least a first layer that is in contact with the solid electrolyte layer and covers at least a part of the solid electrolyte layer, and may include the first layer and a second layer that covers the first layer. Examples of the first layer include a layer containing conductive particles and metal foil. Examples of the conductive particles include at least one type selected from conductive carbon and metal powder. For example, the cathode extraction layer may be composed of a layer containing conductive carbon as the first layer and a layer containing metal powder or metal foil as the second layer. When metal foil is used as the first layer, the cathode extraction layer may be composed of this metal foil.

[0044] The first layer containing conductive carbon can be formed, for example, by immersing an anode body having a dielectric layer on which a solid electrolyte layer is formed in a dispersion liquid containing conductive carbon, or by applying a paste containing conductive carbon to the surface of the solid electrolyte layer. As the conductive carbon, for example, graphites such as artificial graphite and natural graphite, and carbon black are used. As the dispersion liquid and paste, for example, a dispersion of conductive carbon in a water-based liquid medium is used.

[0045] The layer containing metal powder as the second layer can be formed, for example, by laminating a composition containing metal powder on the surface of the first layer. For example, a metal paste layer formed using a composition containing metal powder such as silver particles and a resin (binder resin) can be used as the second layer. Although a thermoplastic resin can be used as the resin, it is preferable to use a thermosetting resin such as an imide resin or an epoxy resin.

[0046] When a metal foil is used as the first layer, the type of metal is not particularly limited, but it is preferable to use a valve metal such as aluminum, tantalum, or niobium, or an alloy containing a valve metal. If necessary, the surface of the metal foil may be roughened by etching or the like. The surface of the metal foil may be provided with a chemical conversion film, or may be provided with a coating of a metal (heterogeneous metal) different from the metal constituting the metal foil or a nonmetal. Examples of the heterogeneous metal or nonmetal include metals such as titanium and nonmetals such as carbon (e.g., conductive carbon).

[0047] The coating of the dissimilar metal or non-metal (eg, conductive carbon) may be the first layer, and the metal foil may be the second layer.

[0048] The electrode potential P1 of the first layer can be adjusted by selecting the material, shape, etc. of the first layer.

[0049] The thickness of the first layer is, for example, 0.1 μm or more and 100 μm or less, alternatively 0.5 μm or more and 50 μm or less, or may be 1 μm or more and 20 μm or less.

[0050] The thickness of the second layer is, for example, 0.1 μm or more and 100 μm or less, alternatively 0.5 μm or more and 50 μm or less, or may be 1 μm or more and 20 μm or less.

[0051] (Separator) When a metal foil is used for the cathode extraction layer, a separator may be disposed between the metal foil and the anode body. The separator is not particularly limited, and may be, for example, a nonwoven fabric containing fibers of cellulose, polyethylene terephthalate, vinylon, or polyamide (e.g., aliphatic polyamide, aromatic polyamide such as aramid).

[0052] (others) The electrolytic capacitor may be of wound type, chip type or laminate type. For example, the electrolytic capacitor may include a laminate of two or more capacitor elements. The configuration of the capacitor elements may be selected according to the type of electrolytic capacitor.

[0053] In the capacitor element, one end of a cathode terminal is electrically connected to the cathode extraction layer. body A conductive adhesive is applied to the cathode via the conductive adhesive. body One end of an anode terminal is electrically connected to the anode body. The other end of the anode terminal and the other end of the cathode terminal are each extended from the resin exterior body. anode terminal The other end and the other end of the cathode terminal, is used for soldering to a substrate (not shown) on which the electrolytic capacitor is to be mounted.

[0054] The capacitor element is sealed with a resin exterior body or case. For example, the capacitor element and the resin material of the exterior body (e.g., uncured thermosetting resin and filler) may be housed in a mold, and the capacitor element may be sealed with the resin exterior body by transfer molding, compression molding, or the like. At this time, the other end side portions of the anode terminal and the cathode terminal connected to the anode lead drawn out from the capacitor element are exposed from the mold. Alternatively, the capacitor element may be housed in a bottomed case such that the other end side portions of the anode terminal and the cathode terminal are positioned on the opening side of the bottomed case, and the opening of the bottomed case may be sealed with a sealer to form an electrolytic capacitor.

[0055] Fig. 1 is a cross-sectional view showing a schematic structure of an electrolytic capacitor according to one embodiment of the present invention. As shown in Fig. 1, the electrolytic capacitor 1 includes a capacitor element 2, a resin exterior housing 3 that seals the capacitor element 2, and an anode terminal 4 and a cathode terminal 5, at least a portion of which is exposed to the outside of the resin exterior housing 3. The anode terminal 4 and the cathode terminal 5 can be made of a metal such as copper or a copper alloy. The resin exterior housing 3 has an outer shape of a substantially rectangular parallelepiped, and the electrolytic capacitor 1 also has an outer shape of a substantially rectangular parallelepiped.

[0056] Capacitor element 2 includes an anode body 6, a dielectric layer 7 covering anode body 6, and a cathode body 8 covering dielectric layer 7. Cathode body 8 includes a solid electrolyte layer 9 covering dielectric layer 7, and a cathode extraction layer 10 covering solid electrolyte layer 9. In the illustrated example, cathode extraction layer 10 has a carbon layer 11 as a first layer and a metal paste layer 12 as a second layer. The electrode potential P of solid electrolyte layer 9 s is higher than the electrode potential P1 of the carbon layer 11 in contact with the solid electrolyte layer 9. This suppresses the oxidation degradation of the conductive polymer contained in the solid electrolyte layer 9, thereby suppressing an increase in ESR. Also, a decrease in capacitance is suppressed. This improves the reliability of the electrolytic capacitor.

[0057] The anode body 6 includes a region facing the cathode body 8 and a region not facing the cathode body 8. In the region of the anode body 6 not facing the cathode body 8, an insulating separation layer 13 is formed in a strip-like shape covering the surface of the anode body 6 in a portion adjacent to the cathode body 8, and contact between the cathode body 8 and the anode body 6 is restricted. In the region of the anode body 6 not facing the cathode body 8, Other than the part adjacent to the cathode body 8 The other part is electrically connected by welding to anode terminal 4. Cathode terminal 5 is electrically connected to cathode body 8 via adhesive layer 14 formed of a conductive adhesive.

[0058] [Example] The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0059] " Example 1 》 An electrolytic capacitor 1 (electrolytic capacitor A1) shown in FIG. 1 was produced in the following manner, and its characteristics were evaluated.

[0060] (1) Preparation of anode body 6 An anode body 6 was produced by roughening both surfaces of an aluminum foil (thickness: 100 μm) used as a substrate by etching.

[0061] (2) Formation of Dielectric Layer 7 The other end of the anode body 6 was immersed in a chemical conversion solution, and a direct current voltage of 70 V was applied for 20 minutes to form a dielectric layer 7 containing aluminum oxide.

[0062] (3) Formation of solid electrolyte layer 9 An aqueous solution containing a pyrrole monomer and p-toluenesulfonic acid was prepared, the monomer concentration in the aqueous solution being 0.5 mol / L and the p-toluenesulfonic acid concentration being 0.3 mol / L.

[0063] The anode body 6 on which the dielectric layer 7 was formed in the above (2) and a counter electrode were immersed in the obtained aqueous solution, and electrolytic polymerization was performed at 25° C. and a polymerization voltage of 3 V (polymerization potential relative to the silver reference electrode) to form a solid electrolyte layer 9.

[0064] (4) Formation of cathode body 8 Anode body 6 having solid electrolyte layer 9 formed thereon obtained in (3) above was immersed in a dispersion liquid in which graphite particles were dispersed in water, and after being removed from the dispersion liquid, was dried to form carbon layer 11 at least on the surface of solid electrolyte layer 9. Drying was performed at 130 to 180° C. for 10 to 30 minutes.

[0065] Next, a silver paste containing silver particles and a binder resin (epoxy resin) was applied to the surface of carbon layer 11, and the binder resin was cured by heating at 150 to 200°C for 10 to 60 minutes to form metal paste layer 12. In this way, cathode body 8 composed of carbon layer 11 and metal paste layer 12 was formed.

[0066] Capacitor element 2 was produced as described above.

[0067] (5) Assembling electrolytic capacitor 1 Cathode body 8 of capacitor element 2 obtained in (4) above was joined to one end of cathode terminal 5 with adhesive layer 14 of a conductive adhesive. One end of anode body 6 protruding from capacitor element 2 was joined to one end of anode terminal 4 by laser welding.

[0068] Next, a resin outer casing 3 made of an insulating resin was formed around the capacitor element 2 by molding. At this time, the other end of the anode terminal 4 and the other end of the cathode terminal 5 were pulled out from the resin outer casing 3.

[0069] In this manner, electrolytic capacitor A1 was completed. In the same manner as above, a total of 20 electrolytic capacitors A1 were produced.

[0070] (6) Evaluation The electrolytic capacitors or capacitor elements were used to carry out the following evaluations.

[0071] (a) Electrode potential P s and P1 Using the capacitor element 2, the electrode potential P s The electrode potential P1 of the carbon layer 11 as the first layer was also measured.

[0072] (b) Rate of change of ESR and rate of change of capacitance In an environment of 20°C, the initial capacitance (μF) of each electrolytic capacitor was measured at a frequency of 120 kHz using a four-terminal LCR meter, and the initial ESR (mΩ) was measured at a frequency of 100 kHz. The average value for the 20 electrolytic capacitors was then calculated.

[0073] Next, an accelerated test was performed by applying the rated voltage to the electrolytic capacitors for 500 hours in an environment of 145°C and 0.4% RH. After that, the capacitance and ESR were measured in an environment of 20°C using the same procedure as for the initial capacitance and ESR, and the average value of the 20 electrolytic capacitors was calculated. Average initial capacitance for Capacitance after accelerated testing Average Ratio (%) to capacitance of The change rate (ΔCap) was calculated. The average initial ESR for The ratio (%) of the average ESR value after the accelerated test is ESR of The change was calculated as the rate of change (ΔESR).

[0074] " Examples 2 to 3 and Comparative Examples 1 to 3 》 In (3) of Example 1, the concentration of p-toluenesulfonic acid in the aqueous solution was changed, and the polymerization voltage was changed to perform electrolytic polymerization. Except for these, a capacitor element and an electrolytic capacitor were produced in the same manner as in Example 1, and evaluated.

[0075] The evaluation results are shown in Table 1. In Table 1, Electrolytic capacitors A1 to A3 are, each Working Example 1~3 and Electrolytic capacitors B1 to B3 are: each Comparative Example 1~3 It is.

[0076] [Table 1] [Industrial Applicability]

[0077] According to the present disclosure, an electrolytic capacitor with excellent reliability is provided, in which an increase in ESR or a decrease in capacitance is suppressed. Such an electrolytic capacitor can be used in various applications requiring high reliability. [Explanation of symbols]

[0078] 1: electrolytic capacitor, 2: capacitor element, 3: resin exterior body, 4: anode terminal, 4S: main surface of anode terminal, 5: cathode terminal, 5S: main surface of cathode terminal, 6: anode body, 7: dielectric layer, 8: cathode body, 9: solid electrolyte layer, 10: cathode lead layer, 11: carbon layer, 12: metal paste layer, 13: separation layer, 14: adhesive layer

Claims

1. A capacitor element is provided, the capacitor element includes an anode body, a dielectric layer formed on a surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, and a first layer in contact with the solid electrolyte layer and covering at least a portion of the solid electrolyte layer, the first layer constitutes at least a part of a cathode extraction layer, The electrode potential P of the solid electrolyte layer ｓ is the electrode potential P of the first layer １ Higher than the electrode potential P s is 0.5 V or less; The solid electrolyte layer comprises a conductive polymer.

2. P ｓ and P １ The electrolytic capacitor according to claim 1 , wherein the difference between the voltage Vcc and the voltage Vs is 0.02 V or more.

3. P ｓ The electrolytic capacitor according to claim 1 or 2, wherein the voltage Vcc is greater than 0.2 V.

4. The electrolytic capacitor according to claim 1 , wherein the first layer comprises conductive carbon.

5. the cathode extraction layer includes the first layer and a second layer covering at least a portion of the first layer, The electrolytic capacitor of claim 1 , wherein the second layer comprises a metal powder.

6. The electrolytic capacitor according to any one of claims 1 to 5, comprising a stack of two or more of the capacitor elements.

7. an anode body; a dielectric layer formed on a surface of the anode body; a solid electrolyte layer covering at least a portion of the dielectric layer; and a first layer in contact with the solid electrolyte layer and covering at least a portion of the solid electrolyte layer, the first layer constitutes at least a part of a cathode extraction layer, The electrode potential P of the solid electrolyte layer ｓ is the electrode potential P of the first layer １ Higher than the electrode potential P s is 0.5 V or less; The capacitor element, wherein the solid electrolyte layer contains a conductive polymer.

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