Solid electrolytic capacitor element and solid electrolytic capacitor

Abstract

This solid electrolytic capacitor element comprises: a positive electrode body; a dielectric layer formed on a surface of the positive electrode body; and a negative electrode part covering at least a portion of the dielectric layer. The negative electrode part is provided with a solid electrolyte layer covering at least a portion of the dielectric layer. The solid electrolyte layer contains a conductive polymer component containing a conjugated polymer. The solid electrolyte layer has an oxygen permeability P1, when heated at 230°C for five hours, of not more than 1.0 cm3 / m2·24h·atm. Using this solid electrolytic capacitor element, it is possible to provide a solid electrolytic capacitor element and a solid electrolytic capacitor having excellent heat resistance.

Description

[Technical Field]

[0001] The present disclosure relates to a solid electrolytic capacitor element and a solid electrolytic capacitor. [Background technology]

[0002] The solid electrolytic capacitor includes a solid electrolytic capacitor element, a resin outer casing or case that seals the solid electrolytic capacitor element, and external electrodes electrically connected to the solid electrolytic capacitor element. The solid electrolytic capacitor element includes an anode body, a dielectric layer formed on the surface of the anode body, and a cathode portion that covers at least a portion of the dielectric layer. The cathode portion includes a solid electrolyte layer containing a conductive polymer component that covers at least a portion of the dielectric layer.

[0003] Patent Document 1 proposes a solid electrolytic capacitor that includes an anode made of at least a valve metal, a dielectric film formed on the valve metal, and a solid electrolyte layer made of a conductive polymer formed on the dielectric film, in which the conductive polymer is a composite of an ionic polymer. Patent Document 1 describes that the conductive polymer is formed by chemical polymerization or electrolytic polymerization. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-21410 Summary of the Invention

[0005] A solid electrolytic capacitor element according to a first aspect of the present disclosure includes an anode body, a dielectric layer formed on a surface of the anode body, and a cathode portion covering at least a portion of the dielectric layer, the cathode portion including a solid electrolyte layer covering at least a portion of the dielectric layer, the solid electrolyte layer including a conductive polymer component including a conjugated polymer, and of Heat at 230℃ for 5 hours rear The oxygen permeability P1 is 1.0 cm 3 / m2 ·24h·atm or less.

[0006] A solid electrolytic capacitor according to a second aspect of the present disclosure includes at least one of the above solid electrolytic capacitor elements.

[0007] According to the present disclosure, a solid electrolytic capacitor element and a solid electrolytic capacitor having excellent heat resistance can be provided. [Brief explanation of the drawings]

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

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

[0010] When air penetrates into a solid electrolytic capacitor, the moisture or oxygen contained in the air causes the conductive polymer components (conjugated polymers, dopants, etc.) to deteriorate. The deterioration of the conductive polymer components reduces the conductivity of the solid electrolyte layer. Furthermore, if the orientation of the conjugated polymers in the solid electrolyte layer is low, air is more likely to penetrate when the solid electrolytic capacitor is exposed to high temperatures. Therefore, the deterioration of the conductive polymer components is particularly pronounced in high-temperature environments. Depending on the application, solid electrolytic capacitors may be used in high-temperature environments. Furthermore, solid electrolytic capacitors are generally solder-bonded to a substrate through a reflow process that exposes them to high temperatures. Therefore, there is a demand for solid electrolytic capacitor elements and solid electrolytic capacitors with excellent heat resistance.

[0011] In view of the above-mentioned problems, in the solid electrolytic capacitor element according to the first aspect of the present disclosure, the penetration of air (more specifically, oxygen) into the solid electrolyte layer when exposed to high temperatures is suppressed to a low level. of 230℃ for 5 hours of heating rear The oxygen permeability P1 is 1.0 cm 3 / m 2 ·24h·atm or less. In addition, 1cm 3 / m 2 24h atm=9.87mL / m 2 ·day·MPa.

[0012] In the solid electrolytic capacitor element of the first aspect, high orientation of the conjugated polymer in the solid electrolyte layer is achieved. The high orientation of the conjugated polymer improves the crystallinity of the conjugated polymer and energetically stabilizes the conjugated polymer. This results in a dense, rigid solid electrolyte layer with excellent film quality. As a result, the oxygen permeability in the solid electrolyte layer can be kept low, and high conductivity of the solid electrolyte layer can be ensured. Even when exposed to high temperatures, deterioration of the solid electrolyte layer is suppressed, and a decrease in capacitor performance (such as capacitance) can be suppressed. This ensures high heat resistance of the solid electrolytic capacitor element and solid electrolytic capacitor. The excellent heat resistance improves the reliability of the solid electrolytic capacitor element and solid electrolytic capacitor.

[0013] Such a solid electrolyte layer can be formed by three-electrode electropolymerization. Conventional electropolymerization is typically performed using a bipolar system, where an anode body with a dielectric layer formed on its surface is used as the anode, and two electrodes, the anode and a counter electrode, are used. In contrast, three-electrode electropolymerization is performed using three electrodes, an anode body with a dielectric layer formed on its surface, the anode, a counter electrode, and a reference electrode. In three-electrode electropolymerization, the use of a reference electrode allows for precise control of the anode potential without being affected by changes in the counter electrode's natural potential. Therefore, in the three-electrode system, the electropolymerization reaction is more precisely controlled than in the two-electrode system, resulting in enhanced orientation of the conjugated polymer formed by electropolymerization, improved crystallinity, and energetically stabilized conjugated polymers. In both the two-electrode and three-electrode systems, the solid electrolyte layer can be formed by electropolymerizing a conjugated polymer precursor on the surface of a dielectric layer, optionally in the presence of a dopant.

[0014] The solid electrolyte layer has an oxygen permeability P1 and an oxygen permeability P0 before heating, and the difference (P1-P0) is 0.3 cm 3 / m 2 ·24h·atm or less is preferable, and 0.25cm 3 / m 2 24h atm or less. In this case, the heat resistance of the solid electrolytic capacitor element and the solid electrolytic capacitor can be further improved. More specifically, even when the solid electrolytic capacitor element is exposed to high temperatures, oxidation reactions are less likely to proceed, deterioration of the solid electrolyte layer is suppressed, high conductivity is maintained, and deterioration of capacitor performance (such as capacitance) is further suppressed.

[0015] The solid electrolytic capacitor element may be heat-treated at a temperature exceeding 200° C. and not exceeding 300° C. In a conventional solid electrolytic capacitor element, when heat-treated at such a temperature, an oxidation reaction proceeds, and the oxygen permeability becomes 1.0 cm or less. 3 / m 2 ·24h·atm Larger, usually 1.3cm 3 / m 2The oxygen permeability of the solid electrolytic capacitor element of the present disclosure is reduced after heat treatment at the above-mentioned temperatures due to the excellent film quality of the solid electrolyte layer. This results in high heat resistance for the solid electrolytic capacitor element and the solid electrolytic capacitor. The heat treatment may be performed for, for example, one hour or more.

[0016] In this specification, the oxygen permeability of the solid electrolyte layer refers to the oxygen permeability (cm ) measured in accordance with JIS K7126-2:2006 using a sample having a solid electrolyte layer with a thickness of 4 μm. 3 / m 2 The oxygen permeability P0 was measured using a polyethylene terephthalate (PET) film (100 mm long x 100 mm wide). beside A sample (sample A) is used in which a 4 μm-thick solid electrolyte layer is formed on one surface of a substrate (100 mm x 100 μm thick) under the same conditions as when forming the solid electrolyte layer of a solid electrolytic capacitor element. If a precoat layer is formed in the formation of the solid electrolyte layer of a solid electrolytic capacitor element, a 0.1 μm-thick precoat layer is formed before forming the solid electrolyte layer of the sample. The oxygen permeability P1 is the oxygen permeability measured after heating sample A at 230°C for 5 hours. For example, the solid electrolyte layer of the sample used for oxygen permeability measurement is formed to have the same degree of crystallinity as the solid electrolyte layer of the solid electrolytic capacitor element. In other words, the Raman spectrum of the solid electrolyte layer of the sample may roughly correspond to the Raman spectrum of the solid electrolyte layer of the solid electrolytic capacitor element. Specifically, if C derived from a conjugated polymer is detected in the Raman spectrum of the solid electrolyte layer of the sample, =The full width at half maximum of the peak (first peak) attributed to the C stretching vibration may be within ±5% of the full width at half maximum of the first peak in the Raman spectrum of the solid electrolyte layer of the solid electrolytic capacitor element. Alternatively, the shift amount of the first peak in the Raman spectrum of the solid electrolyte layer of the sample from the reference position may be within ±5% of the shift amount of the first peak in the Raman spectrum of the solid electrolyte layer of the solid electrolytic capacitor element from the reference position. Note that the Raman spectrum of the solid electrolyte layer, the reference position, and the shift amount of the first peak can be referenced in the description of the Raman spectrum below. The oxygen permeability is measured, for example, under the following conditions.

[0017] Apparatus: MOCON oxygen permeability measuring device OXTRAN2 / 21 Detector: Coulometric sensor Measurement temperature: 23℃ Relative humidity: 60%RH

[0018] Hereinafter, the solid electrolytic capacitor and solid electrolytic capacitor element (hereinafter sometimes simply referred to as capacitor element) of the present disclosure will be described in more detail with reference to the drawings as necessary.

[0019] [Solid electrolytic capacitor] A solid electrolytic capacitor includes one or more capacitor elements. At least one of the capacitor elements included in the solid electrolytic capacitor may have a solid electrolyte layer exhibiting the above-mentioned oxygen permeability. It is preferable that 50% or more (more preferably 75% or more) of the capacitor elements included in the solid electrolytic capacitor have a solid electrolyte layer exhibiting the above-mentioned oxygen permeability, and it is even more preferable that all of the capacitor elements have a solid electrolyte layer exhibiting the above-mentioned oxygen permeability.

[0020] (Capacitor element) (anode body) The anode body can contain a valve metal, an alloy containing a valve metal, a compound containing a valve metal, or the like. These materials can be used alone or in combination. Examples of preferred valve metals include aluminum, tantalum, niobium, and titanium. Anode bodies having a porous surface can be obtained by roughening the surface of a substrate containing a valve metal (such as a sheet-like (e.g., foil-like, plate-like) substrate) by etching or the like. Surface roughening can be achieved by etching or the like. The anode body can also be a compact or sintered body of particles containing a valve metal. The compact and sintered body each have a porous structure. The compact and sintered body each can be in the form of a sheet, a rectangular parallelepiped, a cube, or similar shapes.

[0021] The anode body typically has an anode lead portion and a cathode forming portion. The cathode portion is typically formed on the cathode forming portion of the anode body via a dielectric layer. An anode terminal is connected to the anode lead portion.

[0022] (dielectric layer) The dielectric layer is an insulating layer that functions as a dielectric and is formed so as to cover at least a portion of the surface of the anode body. The dielectric layer is formed by anodizing the valve metal on the surface of the anode body using a chemical conversion treatment or the like. The dielectric layer may be formed so as to cover at least a portion of the anode body. The dielectric layer is usually formed on the surface of the anode body. Because the dielectric layer is formed on the porous surface of the anode body, the surface of the dielectric layer has a fine uneven shape as described above.

[0023] 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, as long as it functions as a dielectric.

[0024] (cathode) The cathode section includes a solid electrolyte layer that covers at least a portion of the dielectric layer. The cathode section may further include a cathode extraction layer that covers at least a portion of the solid electrolyte layer. The cathode section is usually formed on at least a portion of the surface of the anode body via a dielectric layer. The solid electrolyte layer and the cathode extraction layer are described below.

[0025] (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 only needs to cover at least a portion of the dielectric layer. The solid electrolyte layer constitutes at least a portion of the cathode part of the solid electrolytic capacitor.

[0026] The solid electrolyte layer usually contains a conductive polymer component, which contains at least a conjugated polymer and may further contain a dopant as needed.

[0027] (conjugated polymers) The conjugated polymer may be a known conjugated polymer used in electrolytic capacitors, such as a π-conjugated polymer. Examples of conjugated polymers include polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, polyfuran, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polythiophene vinylene. The above polymers may contain at least one monomer unit constituting the basic skeleton. The monomer unit may also include a monomer unit having a substituent. The above polymers may also include homopolymers and copolymers of two or more monomers.

[0028] Among conjugated polymers, preferred are conjugated polymers containing at least one monomer unit selected from the group consisting of pyrrole compounds, thiophene compounds, and aniline compounds. Examples of pyrrole compounds include compounds having a pyrrole ring and capable of forming a repeating structure of the corresponding monomer unit. Examples of thiophene compounds include compounds having a thiophene ring and capable of forming a repeating structure of the corresponding monomer unit. These compounds can be linked at the 2- and 5-positions of the pyrrole or thiophene ring to form a repeating structure of the monomer unit, thereby forming a polymer with a π electron cloud spread throughout the molecule. Examples of aniline compounds include compounds having a benzene ring and at least one (preferably one) amino group bonded to the benzene ring and capable of forming a repeating structure of the corresponding monomer unit. For example, aniline compounds can be linked at the amino group and the CH group (CH group constituting the benzene ring) at the p-position relative to the amino group to form a repeating structure of the monomer unit, thereby forming a polymer with a π electron cloud spread throughout the molecule.

[0029] The pyrrole compound may have a substituent at, for example, at least one of the 3rd and 4th positions of the pyrrole ring. The thiophene compound may have a substituent at, for example, at least one of the 3rd and 4th positions of the thiophene ring. The substituent at the 3rd position and the substituent at the 4th position may be linked to form a ring fused to the pyrrole ring or the thiophene ring. Examples of the pyrrole compound include pyrrole which may have a substituent at, for example, at least one of the 3rd and 4th positions. Examples of the thiophene compound include thiophene which may have a substituent at, for example, at least one of the 3rd and 4th positions, alkylenedioxythiophene compounds (C thiophenes such as ethylenedioxythiophene compounds), etc. 2-4 Examples of the alkylenedioxythiophene compound include those having a substituent in the alkylene group. Examples of the aniline compound include aniline that may have a substituent in at least one of the o-position and p-position relative to the amino group.

[0030] The substituents include alkyl groups (C such as methyl and ethyl groups) 1-4 alkyl groups, alkoxy groups (methoxy groups, ethoxy groups, etc.) 1-4 Alkoxy groups, hydroxy groups, hydroxyalkyl groups (hydroxy C groups such as hydroxymethyl groups) 1-4 Preferred examples include, but are not limited to, alkyl groups. When each of the pyrrole compound, the thiophene compound, and the aniline compound has two or more substituents, the substituents may be the same or different.

[0031] In particular, the use of a conjugated polymer containing at least a monomer unit corresponding to pyrrole, or a conjugated polymer (such as poly(3,4-ethylenedioxythiophene) (PEDOT)) containing at least a monomer unit corresponding to a 3,4-ethylenedioxythiophene compound (such as 3,4-ethylenedioxythiophene (EDOT)), can further improve the film quality of the solid electrolyte layer. This enhances the effect of reducing the oxygen permeability of the solid electrolyte layer. In addition, high heat resistance is easily achieved, and higher conductivity of the solid electrolyte layer is easily ensured. A conjugated polymer containing at least a monomer unit corresponding to pyrrole may contain only a monomer unit corresponding to pyrrole, or may contain, in addition to the monomer unit, a monomer unit corresponding to a pyrrole compound other than pyrrole (such as a pyrrole having a substituent). A conjugated polymer containing at least a monomer unit corresponding to EDOT may contain only a monomer unit corresponding to EDOT, or may contain, in addition to the monomer unit, a monomer unit corresponding to a thiophene compound other than EDOT.

[0032] In a conjugated polymer containing a monomer unit corresponding to a pyrrole compound, from the viewpoint of easily ensuring a higher capacitance, the molar ratio of the monomer unit corresponding to the pyrrole compound (or pyrrole) is preferably 50 mol% or more, more preferably 75 mol% or more. The molar ratio of the monomer unit corresponding to the pyrrole compound (or pyrrole) in the conjugated polymer is 100 mol% or less. The conjugated polymer may be composed only of a repeating structure of the monomer unit corresponding to the pyrrole compound (or pyrrole).

[0033] In a conjugated polymer containing a monomer unit corresponding to a thiophene compound, from the viewpoint of easily ensuring a higher capacitance, the molar ratio of the monomer unit corresponding to the thiophene compound (or EDOT) is preferably 50 mol% or more, more preferably 75 mol% or more. The molar ratio of the monomer unit corresponding to the thiophene compound (or EDOT) in the conjugated polymer is 100 mol% or less. The conjugated polymer may be composed only of a repeating structure of the monomer unit corresponding to the thiophene compound (or EDOT).

[0034] The conjugated polymer may be used alone or in combination of two or more kinds.

[0035] The weight average molecular weight (Mw) of the conjugated polymer is not particularly limited and is, for example, 1,000 or more and 1,000,000 or less.

[0036] (dopant) As the dopant, for example, at least one selected from the group consisting of anions and polyanions is used.

[0037] Examples of anions include, but are not limited to, sulfate ions, nitrate ions, phosphate ions, borate ions, organic sulfonate ions, carboxylate ions, etc. Examples of dopants that generate sulfonate ions include p-toluenesulfonic acid and naphthalenesulfonic acid.

[0038] Examples of polyanions include polymer anions. The solid electrolyte layer may contain, for example, a conjugated polymer containing a monomer unit corresponding to a thiophene compound and a polymer anion. When the solid electrolytic capacitor contains a polymer anion, undoping is less likely to occur even when the solid electrolytic capacitor element is exposed to high temperatures, resulting in higher heat resistance.

[0039] Examples of polymer anions include polymers having multiple anionic groups. Such polymers include polymers containing monomer units having anionic groups. Examples of the anionic groups include sulfonic acid groups and carboxyl groups.

[0040] In the solid electrolyte layer, the anionic group of the dopant may be contained in a free form, an anion form, or a salt form, or may be contained in a form bound to or interacting with the conjugated polymer. In this specification, all of these forms may be simply referred to as an "anionic group," "sulfonic acid group," "carboxy group," or the like.

[0041] Examples of polymer anions having a carboxy group include, but are not limited to, polyacrylic acid, polymethacrylic acid, and copolymers using at least one of acrylic acid and methacrylic acid.

[0042] Specific examples of polymer anions having sulfonic acid groups include, but are not limited to, polymeric polysulfonic acids such as polyvinyl sulfonic acid, polystyrene sulfonic acid (including copolymers and substituted products having substituents), polyallylsulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, polyester sulfonic acids (such as aromatic polyester sulfonic acids), and phenolsulfonic acid novolac resins.

[0043] The amount of the dopant contained in the solid electrolyte layer is, for example, 10 to 1000 parts by mass, or may be 20 to 500 parts by mass, or 50 to 200 parts by mass, relative to 100 parts by mass of the conjugated polymer.

[0044] (oxygen permeability) When the solid electrolyte layer was heated at 230°C for 5 hours, the oxygen permeability P1 was 1.0 cm 3 / m 2 ·24h·atm or less, 0.9cm 3 / m 2 ·24h·atm or less is preferable, 0.8cm 3 / m 2 ·24h·atm or less, 0.7cm 3 / m 2 24h·atm or less. A solid electrolyte layer exhibiting such an oxygen permeability P1 has a high degree of orientation of the conjugated polymer, and the conjugated polymer is in a state of being energetically stabilized. In addition, such a solid electrolyte layer has a dense film quality and high conductivity. Therefore, in the solid electrolytic capacitor element and solid electrolytic capacitor, deterioration of the solid electrolyte layer when exposed to high temperatures is suppressed, and a decrease in capacitor performance such as capacitance is suppressed. Therefore, high heat resistance is obtained. The oxygen permeability P1 of the solid electrolyte layer is, for example, 0.01 cm 3 / m 2 ·24h·atm or above.

[0045] For example, the oxygen permeability P1 of a solid electrolyte layer containing polypyrrole and a dopant (such as naphthalene sulfonic acid) formed by bipolar electrolytic polymerization is 1.0 cm 3 / m 2 Higher than 24h atm, typically 1.3cm 3 / m 2 24h atm or more. The oxygen permeability P1 of the solid electrolyte layer formed using a liquid dispersion containing polypyrrole and a dopant (such as polystyrene sulfonic acid) is usually 1.3 cm 3 / m 2The oxygen permeability P1 of the solid electrolyte layer formed by chemical polymerization using a polymerization solution containing pyrrole and a dopant (such as naphthalene sulfonic acid) is usually 1.5 cm 3 / m 2 ·24h·atm or above.

[0046] The oxygen permeability P1 of the solid electrolyte layer containing PEDOT and dopants (such as polystyrene sulfonate) formed by bipolar electropolymerization is 1.0 cm 3 / m 2 Higher than 24h atm, typically 1.3cm 3 / m 2 24h atm or more. The oxygen permeability P1 of the solid electrolyte layer formed using a liquid dispersion containing PEDOT and a dopant (such as polystyrene sulfonic acid) is typically 1.3 cm 3 / m 2 The oxygen permeability P1 of the solid electrolyte layer formed by chemical polymerization using a polymerization solution containing EDOT and a dopant (such as polystyrene sulfonic acid) is typically 1.5 cm 3 / m 2 ·24h·atm or above.

[0047] In the solid electrolytic capacitor element of the first aspect, the solid electrolyte layer has excellent film quality, so that the oxygen permeability of the solid electrolyte layer can be kept low even when exposed to high temperatures. of heating rear The difference (P1-P0) between the oxygen permeability P1 before heating and the oxygen permeability P0 before heating is, for example, 0.3 cm 3 / m 2 ·24h·atm or less, 0.25cm 3 / m 2 In addition, in the conventional solid electrolytic capacitor element, the solid electrolyte layer has poor film quality and the oxygen permeability P1 is large, so the value of (P1 - P0) is 0.5 cm 3 / m 2 This is a large value exceeding 24h atm.

[0048] The solid electrolytic capacitor element may be heat-treated at a high temperature exceeding 200°C, for example. The heat treatment temperature is, for example, above 200°C and not exceeding 300°C, and may be 210°C to 300°C, or 210°C to 250°C. Conventional solid electrolytic capacitor elements have poor solid electrolyte layer quality, so when heat-treated at such high temperatures, the conductive polymer component deteriorates, increasing the oxygen permeability of the solid electrolyte layer and reducing its conductivity. This results in a decrease in capacitor performance, such as capacitance. However, in the solid electrolytic capacitor element of the first aspect, the excellent film quality of the solid electrolyte layer is maintained even when heat-treated at a high temperature, ensuring high capacitor performance.

[0049] The heat treatment time is, for example, 1 hour or more, or may be 2 hours or more, or may be 3 hours or more. The heat treatment time is, for example, 10 hours or less, or may be 6 hours or less, or 5 hours or less. These lower and upper limits can be combined in any manner.

[0050] The heat treatment may be performed in air or in an inert gas atmosphere. The atmosphere for the heat treatment can be selected depending on the stage at which the heat treatment is performed. For example, when the heat treatment is performed after forming the cathode extraction layer, the heat treatment may be performed in air.

[0051] (Raman spectrum) In the solid electrolytic capacitor element and solid electrolytic capacitor of the present disclosure, the solid electrolyte layer exhibits high crystallinity due to the high orientation of the conjugated polymer. Furthermore, in the solid electrolyte layer, the conjugated polymer is in an energetically stabilized state. Therefore, the solid electrolyte layer exhibits a characteristic Raman spectrum. The Raman spectrum of the solid electrolyte layer is described in more detail below.

[0052] The main component of the solid electrolyte layer is a conjugated polymer, and the Raman spectrum of the solid electrolyte layer shows C =The peak (first peak) attributed to the C stretching vibration is the highest and most characteristic. In the solid electrolyte layer, when the orientation of the conjugated polymer increases or the energy state changes, C = The vibrational state of the C bond changes, so C = At least one of the full width at half maximum and the peak position of the first peak attributed to the C stretching vibration changes. = The orientation state or energy state of the conjugated polymer in the solid electrolyte layer can be determined based on at least one of the full width at half maximum and the peak position of the first peak attributed to the C stretching vibration.

[0053] In the Raman spectrum of the solid electrolyte layer, the full width at half maximum of the first peak when fitted with a Lorentzian function is 80 cm -1 It is preferable that the solid electrolytic capacitor element has a full width at half maximum of 35 cm or less. In this case, the orientation of the conjugated polymer in the solid electrolyte layer is further enhanced, improving the film quality. Therefore, the oxygen permeability of the solid electrolyte layer can be kept low, and high conductivity can be ensured. Furthermore, even when the solid electrolytic capacitor element is exposed to high temperatures, oxidation reactions are unlikely to proceed, and deterioration of the solid electrolyte layer is suppressed, thereby maintaining high conductivity and suppressing deterioration of capacitor performance such as capacitance. By obtaining high heat resistance of the solid electrolytic capacitor element and the solid electrolytic capacitor, reliability can be improved. The full width at half maximum of the first peak is, for example, 35 cm or less. -1 In this case, a solid electrolyte layer can be easily formed. From the viewpoint of obtaining a higher degree of orientation of the conjugated polymer, the full width at half maximum of the first peak is set to 50 cm. -1 It may be more than 55cm -1 or above or 58cm -1 When the full width at half maximum of the first peak is in the above range, the oxygen permeability P1 of the solid electrolyte layer may be 1.0 cm or more. 3 / m 2 It can be estimated that it is less than 24h atm.

[0054] In the Raman spectrum of the solid electrolyte layer, it is also preferable that the position of the first peak is shifted to a lower wavenumber from the reference position when the solid electrolyte layer is formed by bipolar electrolytic polymerization and heated at 230°C for 5 hours. In this case, the orientation of the conjugated polymer in the solid electrolyte layer is enhanced, resulting in an energetically stabilized state of the conjugated polymer. This reduces the oxygen permeability of the solid electrolyte layer and facilitates ensuring high conductivity of the solid electrolyte layer. Furthermore, improved film quality of the solid electrolyte layer makes it difficult for oxidation reactions to proceed, even when the solid electrolytic capacitor element is exposed to high temperatures, maintaining high conductivity and suppressing degradation of capacitor performance such as capacitance. Furthermore, the conjugated polymer is more easily doped with a dopant, reducing the likelihood of the conjugated polymer becoming reduced, thereby preventing oxidation reactions from proceeding. The high heat resistance of the solid electrolytic capacitor element and the solid electrolytic capacitor improves reliability. The reference position is the Raman spectrum of the solid electrolyte layer containing a conjugated polymer formed by bipolar electropolymerization and heated at 230°C for 5 hours, where C originating from the conjugated polymer is observed. = This is the position of the second peak when the peak (second peak) assigned to the C stretching vibration is fitted with a Lorentzian function.

[0055] The shift amount of the first peak position from the reference position is usually 0.2% or more, and preferably 0.25% or more or 0.3% or more. When the shift amount is within this range, the conjugated polymer is in an energetically stabilized state in the solid electrolyte layer, making it difficult for an oxidation reaction to proceed. For example, the conjugated polymer is easily doped with a dopant to an appropriate degree, thereby reducing the conjugated polymer from being in a reduced state. As a result, high heat resistance is obtained. The shift amount is usually 1% or less, and may be 0.7% or less or 0.51% or less. When the shift amount is within this range, the conjugated polymer is easily doped with a dopant to an appropriate degree, thereby preventing excessive decomposition of the dopant contained in the solid electrolyte layer. As a result, high heat resistance is obtained. The lower limit and upper limit of the shift amount can be arbitrarily combined. Note that when the shift amount of the first peak is within the above range, the oxygen permeability P1 is 1.0 cm or less. 3 / m 2 The shift amount is the wave number (cm -1 ) is set to 100%, the actual shift amount (cm) from the reference position of the first peak. -1 ) is the ratio (%) of

[0056] For example, when the conjugated polymer contains at least a monomer unit corresponding to pyrrole, the position of the first peak is 1566 cm -1 Over 1578cm -1 Preferably, it is 1570 cm or less. -1 Over 1577cm -1 The following is more preferable: When the conjugated polymer contains at least a monomer unit corresponding to EDOT, the position of the first peak is 1423 cm -1 Over 1435cm -1 Preferably, it is 1429 cm or less. -1 Over 1434cm -1 It is more preferable that the temperature is not more than 100°C. In these cases, higher heat resistance of the solid electrolytic capacitor element can be ensured.

[0057] The solid electrolytic capacitor for determining the reference position is formed under the same conditions as those for forming a solid electrolytic capacitor using a comparative three-electrode electrolytic polymerization, except that the solid electrolyte layer is formed by two-electrode electrolytic polymerization and heated at 230° C. for 5 hours. The two-electrode electrolytic polymerization is carried out by applying a liquid composition containing a precursor of a conjugated polymer and, if necessary, a dopant to a cathode-forming portion of an anode body having a dielectric layer formed on its surface and a counter electrode. Titanium ( Ti ) The anode body is immersed in the liquid composition and a voltage is applied to the anode body so that the potential of the anode body relative to a silver / silver chloride reference electrode is 3.0 V. The pH of the liquid composition is, for example, 3.0. The conjugated polymer precursor and dopant are the same as those used in the solid electrolytic capacitor formed using the comparable three-electrode electrolytic polymerization. Heating at 230°C is performed in the atmosphere after the cathode extraction layer is formed.

[0058] The solid electrolytic capacitor element may have a first peak full width at half maximum in the above range (condition a), or the shift amount of the first peak position in the above range (condition b), or may satisfy both conditions a and b.

[0059] In this specification, the Raman spectrum of the solid electrolyte layer of a solid electrolytic capacitor element is measured under the following conditions for a cross section of the solid electrolyte layer at a predetermined position of the solid electrolytic capacitor element: The Raman spectrum of the solid electrolyte layer of sample A is measured under the following conditions for a cross section of the solid electrolyte layer parallel to the thickness direction at an arbitrary position of sample A.

[0060] Raman spectrometer: NanoPhoton RamanFORCE PAV Diffraction grating: 600gr / cm Measurement wave number range: 0cm -1 More than 2500cm -1 below Temperature: 25℃

[0061] The wavelength of the irradiated laser light, the laser power density, and the exposure time are determined depending on the type of conjugated polymer. For example, when the conjugated polymer is polypyrrole, the wavelength of the irradiated laser light is 532 nm, and the laser power density is 140 W / cm. 2 The exposure time was 75 seconds. When the conjugated polymer was poly(3,4-ethylenedioxythiophene) (PEDOT), the wavelength of the irradiated laser light was 785 nm and the laser power density was 660 W / cm. 2 and the exposure time is 60 seconds.

[0062] To measure the Raman spectrum of the solid electrolyte layer of a solid electrolytic capacitor element, a sample (Sample B) prepared using the following procedure can be used. First, the solid electrolytic capacitor is embedded in a curable resin, which is then cured. The cured product is polished or cross-section polished to expose a cross section parallel to the thickness direction of the solid electrolyte layer and perpendicular to the length direction of the capacitor element. The cross section is taken at a position 0 to 0.05 from the end of the solid electrolyte layer opposite the anode lead, assuming that the length of the solid electrolyte layer in the direction parallel to the length direction of the capacitor element is 1. In this way, a sample for measurement (Sample B) is obtained. In the cross section of the exposed solid electrolyte layer of Sample B, Raman spectra are measured for a portion (surface portion) from the surface of the solid electrolyte layer to a depth of 100 nm (surface portion) and an 8 μm × 8 μm region in the portion formed within holes and depressions (sometimes called pits) on the surface of the anode body of the solid electrolyte layer. = The full width at half maximum and peak position of the peak attributed to the C stretching vibration were determined by averaging the measured values ​​at six 8 μm × 8 μm areas on the surface and 12 8 μm × 8 μm areas in the pits of the solid electrolyte layer. The cross section of Sample A can be exposed in the same manner as the cross section of Sample B.

[0063] The anode body typically has an anode lead portion including a first end and a cathode formation portion including a second end. The direction from the first end side to the second end side of the anode body is referred to as the longitudinal direction of the anode body or capacitor element. The length of the solid electrolyte layer is the length in a direction parallel to the longitudinal direction of the capacitor element. The direction from the first end side to the second end side of the anode body is the direction parallel to the line connecting the center of the end face of the first end and the center of the end face of the second end.

[0064] (others) The solid electrolyte layer may further contain, as necessary, at least one selected from the group consisting of known additives and known conductive materials other than the conductive polymer component, such as at least one selected from the group consisting of conductive inorganic materials such as manganese dioxide and TCNQ complex salts.

[0065] The solid electrolyte layer may be a single layer or may be composed of multiple layers. For example, the solid electrolyte layer may be composed of a first solid electrolyte layer covering at least a portion of the dielectric layer and a second solid electrolyte layer covering at least a portion of the first solid electrolyte layer. The types, compositions, and contents of conductive polymer components, additives, etc. contained in each layer may be different or the same.

[0066] (Method for forming a solid electrolyte layer) The solid electrolyte layer can be formed on the surface of the dielectric layer by electropolymerizing a conjugated polymer precursor in the presence of a dopant, if necessary, in a three-electrode system. For example, electropolymerization is performed while the cathode-forming portion of the anode body, on whose surface the dielectric layer is formed, is immersed in a liquid composition containing the conjugated polymer precursor and, if necessary, the dopant. This type of electropolymerization can improve the orientation of the conjugated polymer. Furthermore, the dopant is appropriately doped, energetically stabilizing the conjugated polymer. This ensures high heat resistance of the capacitor element.

[0067] Examples of precursors of conjugated polymers include raw material monomers of conjugated polymers, oligomers and prepolymers in which multiple molecular chains of raw material monomers are linked together. One type of precursor may be used, or two or more types may be used in combination. From the viewpoint of easily obtaining higher orientation of the conjugated polymer, it is preferable to use at least one type (particularly a monomer) selected from the group consisting of monomers and oligomers as the precursor.

[0068] Liquid compositions usually contain a solvent, such as water, an organic solvent, or a mixed solvent of water and an organic solvent (such as a water-soluble organic solvent).

[0069] When dopants, other conductive materials, additives, etc. are used, they may be added to the liquid composition.

[0070] The liquid composition may contain an oxidizing agent, if necessary. The oxidizing agent may be applied to the anode body before or after contacting the liquid composition with the anode body on which the dielectric layer has been formed. Examples of such an oxidizing agent include Fe 3+ Examples of the oxidizing agent include compounds capable of generating oxidizing agent (such as ferric sulfate), persulfates (such as sodium persulfate and ammonium persulfate), and hydrogen peroxide. The oxidizing agent can be used alone or in combination of two or more.

[0071] The pH of the liquid composition is, for example, 0.5 to 2.5, preferably 0.5 to 2 or 1 to 2, and may be 1.3 to 1.7. When the pH of the liquid composition is in this range, oxygen generation during electrolytic polymerization can be suppressed, making it easier to obtain a solid electrolyte layer with excellent film quality. The pH of the liquid composition can be adjusted, for example, by adjusting the content of the dopant or the content of the oxidizing agent in the liquid composition.

[0072] The three-electrode electropolymerization is carried out in a state where an anode body, a counter electrode, and a reference electrode are immersed in the liquid composition. The counter electrode may be, but is not limited to, a Ti electrode. The reference electrode may be a silver / silver chloride electrode (Ag / Ag + ) is preferably used.

[0073] In electropolymerization, the voltage (polymerization voltage) applied to the anode body is, for example, 0.6 V or more and 1.5 V or less, or may be 0.7 V or more and 1 V or less, 0.7 V or more and 0.9 V or less, 0.7 V or more and 0.85 V or less, or 0.7 V or more and 0.8 V or less. By performing electropolymerization in a three-electrode system, electropolymerization can be performed at a relatively low polymerization voltage, and the polymerization reaction can be precisely controlled. This further improves the orientation of the conjugated polymer. In addition, the dopant can be appropriately doped. The polymerization voltage is set by using a reference electrode (silver / silver chloride electrode (Ag / Ag + )). In electropolymerization, a power supply (such as a power supply tape) is electrically connected to the anode lead, and a voltage is applied to the anode via the power supply. The potential of the anode is the potential of the power supply electrically connected to the anode.

[0074] The temperature at which electropolymerization is carried out is, for example, 5°C or higher and 60°C or lower, and may be 15°C or higher and 35°C or lower.

[0075] Prior to electropolymerization, a precoat layer may be formed on the surface of the dielectric layer. The precoat layer includes, for example, a conductive material. The precoat layer may be formed using a liquid dispersion containing a conjugated polymer and a dopant. The conjugated polymer of the precoat layer and the conjugated polymer formed by electropolymerization may be the same type or different types. The dopant of the precoat layer and the dopant used in electropolymerization may be the same type or different.

[0076] (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 portion of the solid electrolyte layer, and may also include a 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 selected from conductive carbon and metal powder. For example, the cathode extraction layer may be formed of a first layer containing conductive carbon (also referred to as a carbon layer) and a second layer containing metal powder or metal foil. When metal foil is used as the first layer, the cathode extraction layer may be formed of this metal foil.

[0077] Examples of conductive carbon include graphite (artificial graphite, natural graphite, etc.).

[0078] The second layer containing metal powder can be formed, for example, by laminating a composition containing metal powder on the surface of the first layer. Examples of such second layers include metal paste layers formed using a composition containing metal powder such as silver particles and a resin (binder resin). While thermoplastic resins can be used as the resin, it is preferable to use thermosetting resins such as imide resins and epoxy resins.

[0079] When a metal foil is used as the first layer, the type of metal is not particularly limited. It is preferable to use a valve metal (aluminum, tantalum, niobium, etc.) or an alloy containing a valve metal for the metal foil. If necessary, the surface of the metal foil may be roughened. The surface of the metal foil may be provided with a chemical conversion coating, or with a coating of a metal (dissimilar metal) or a nonmetal different from the metal constituting the metal foil. Examples of dissimilar metals and nonmetals include metals such as titanium and nonmetals such as carbon (e.g., conductive carbon).

[0080] The coating of the dissimilar metal or non-metal (for example, conductive carbon) may be the first layer, and the metal foil may be the second layer.

[0081] (separator) When a metal foil is used for the cathode extraction layer, a separator may be disposed between the metal foil and the anode foil. 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).

[0082] (others) The solid electrolytic capacitor may be a wound type, a chip type, or a laminate type. For example, the solid electrolytic capacitor may include a laminate of two or more capacitor elements. The configuration of the capacitor elements may be selected depending on the type of solid electrolytic capacitor.

[0083] In the capacitor element, one end of a cathode terminal is electrically connected to the cathode extraction layer. The cathode terminal is bonded to the cathode extraction layer, for example, by applying a conductive adhesive to the cathode extraction layer and bonding the cathode terminal to the cathode extraction layer via the conductive adhesive. One end of the 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 or the case. The other end of each terminal exposed from the resin exterior body or the case is used for soldering to a substrate on which the solid electrolytic capacitor is to be mounted, for example.

[0084] The capacitor element is sealed using a resin outer casing or case. For example, the capacitor element and the resin material of the outer casing (e.g., uncured thermosetting resin and filler) may be placed in a mold, and the capacitor element may be sealed in the resin outer casing by transfer molding, compression molding, or the like. At this time, the other end portions of the anode terminal and cathode terminal connected to the anode lead drawn from the capacitor element are exposed from the mold. Alternatively, the capacitor element may be placed in a bottomed case so that the other end portions of the anode terminal and cathode terminal are positioned on the opening side of the bottomed case, and the opening of the bottomed case may be sealed with a sealant to form a solid electrolytic capacitor.

[0085] When the solid electrolytic capacitor element is heat-treated at a temperature exceeding 200° C. as described above, the heat treatment can be carried out at an appropriate stage after the formation of the solid electrolyte layer. For example, the heat treatment may be carried out after the formation of the solid electrolyte layer and before the formation of the cathode extraction layer, or after the formation of the cathode extraction layer and before sealing with a resin outer casing or case, or after sealing.

[0086] Fig. 1 is a cross-sectional view schematically illustrating the structure of a solid electrolytic capacitor according to an embodiment of the present disclosure. As shown in Fig. 1, solid electrolytic capacitor 1 includes a capacitor element 2, a resin outer casing 3 that seals 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 resin outer casing 3. Anode terminal 4 and cathode terminal 5 may be made of a metal such as copper or a copper alloy. Resin outer casing 3 has a substantially rectangular parallelepiped outer shape, and solid electrolytic capacitor 1 also has a substantially rectangular parallelepiped outer shape.

[0087] The capacitor element 2 includes an anode body 6, a dielectric layer 7 covering the anode body 6, and a cathode portion 8 covering the dielectric layer 7. The cathode portion 8 includes a solid electrolyte layer 9 covering the dielectric layer 7, and a cathode extraction layer 10 covering the solid electrolyte layer 9. In the illustrated example, the solid electrolyte layer 9 includes a conductive polymer component including a conjugated polymer.

[0088] The anode body 6 includes a region facing the cathode portion 8 and a region not facing the cathode portion 8. Of the region of the anode body 6 not facing the cathode portion 8, an insulating separator 13 is formed in a strip-like shape on the surface of the anode body 6 in a portion adjacent to the cathode portion 8, thereby restricting contact between the cathode portion 8 and the anode body 6. Of the region of the anode body 6 not facing the cathode portion 8, another part is electrically connected to the anode terminal 4 by welding. The cathode terminal 5 is electrically connected to the cathode portion 8 via an adhesive layer 14 formed of a conductive adhesive.

[0089] [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.

[0090] <Solid electrolytic capacitors A1 to A3> Solid electrolytic capacitors 1 (solid electrolytic capacitors A1 to A3) shown in FIG. 1 were fabricated in the following manner, and their characteristics were evaluated.

[0091] (1) Preparation of anode body 6 Anode body 6 was produced by roughening both surfaces of an aluminum foil (thickness: 100 μm) used as a substrate by etching.

[0092] (2) Formation of dielectric layer 7 The cathode forming portion of the anode body 6 was immersed in the 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.

[0093] (3) Formation of solid electrolyte layer 9 An insulating resist tape was attached to anode body 6 on which dielectric layer 7 was formed, between a region where a solid electrolyte layer was to be formed and a region where a solid electrolyte layer was not to be formed, thereby forming separation portion 13. Anode body 6 on which separation portion 13 was formed was immersed in a liquid composition containing a conductive material, taken out, and dried to form a precoat layer (not shown).

[0094] A polymerization solution containing pyrrole (a monomer for a conjugated polymer), naphthalenesulfonic acid (a dopant), and water was prepared. The pH of the polymerization solution was adjusted by adjusting the amount of naphthalenesulfonic acid added, as shown in Table 1. Using the resulting polymerization solution, electropolymerization was performed using a three-electrode system. More specifically, an anode body 6 on which a precoat layer had been formed, a counter electrode, and a reference electrode (a silver / silver chloride reference electrode) were immersed in the polymerization solution. A voltage was applied to the anode body 6 so that the potential of the anode body 6 relative to the reference electrode was the polymerization voltage value shown in Table 1, and electropolymerization was performed at 25°C to form a solid electrolyte layer 9.

[0095] (4) Formation of the Cathode Extraction Layer 10 Anode body 6 obtained in (3) above was immersed in a dispersion liquid in which graphite particles were dispersed in water, and then removed from the dispersion liquid and dried, thereby forming carbon layer 11 at least on the surface of solid electrolyte layer 9. Drying was carried out at 150°C for 30 minutes.

[0096] 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°C for 30 minutes to form metal paste layer 12. In this way, cathode extraction layer 10 composed of carbon layer 11 and metal paste layer 12 was formed, and cathode part 8 composed of solid electrolyte layer 9 and cathode extraction layer 10 was formed.

[0097] Capacitor element 2 was fabricated in the manner described above.

[0098] (5) Assembly of solid electrolytic capacitors Cathode part 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. Next, a resin outer casing 3 made of 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 left pulled out from the resin outer casing 3.

[0099] In this way, solid electrolytic capacitors 1 (A1 to A4) were completed. In the same manner as above, a total of 20 of each solid electrolytic capacitor were produced.

[0100] <Solid electrolytic capacitors A4 to A6> After forming cathode extraction layer 10, a heat treatment was performed for 5 hours at 230° C. A total of 20 solid electrolytic capacitors A4 to A6 were fabricated in the same manner as solid electrolytic capacitors A1 to A3, except for this.

[0101] <Solid electrolytic capacitor B1> To form the solid electrolyte layer, electropolymerization was performed using a two-electrode system. In the electropolymerization, the anode body on which the precoat layer was formed and a Ti electrode serving as a counter electrode were immersed in a polymerization solution, and a voltage was applied to the anode body so that the potential of the anode body relative to the silver / silver chloride reference electrode reached the polymerization voltage value shown in Table 1. After the cathode extraction layer was formed, the anode body was heat-treated at 230°C for 5 hours. A total of 20 solid electrolytic capacitors B1 were formed in the same manner as solid electrolytic capacitor A1, except for these points.

[0102] [evaluation] The solid electrolytic capacitors or evaluation samples were used to carry out the following evaluations.

[0103] (a) Measurement of oxygen permeability Sample A for measuring oxygen permeability was prepared using the same conditions as when forming the solid electrolyte layer of each solid electrolytic capacitor, using the procedure described above. Using Sample A, the oxygen permeability of the solid electrolyte layer was measured using the procedure described above. Note that for solid electrolytic capacitors A1 to A3, the solid electrolyte layer was not heat-treated, so oxygen permeability P0 was measured. For the other solid electrolytic capacitors, heat treatment at 230°C for 5 hours was performed, so oxygen permeability P1 was measured.

[0104] (b) Raman spectrum measurement of the solid electrolyte layer The Raman spectrum of the cross section of the solid electrolyte layer (sample B) of the capacitor element taken out of the solid electrolytic capacitor was measured using the procedure described above. In the Raman spectrum of the solid electrolyte layer of solid electrolytic capacitor B1, C derived from polypyrrole was observed. = The peak (second peak) assigned to the C stretching vibration is 1582 cm -1 In the Raman spectrum of the solid electrolyte layer of the capacitor element taken out of the solid electrolytic capacitor, the full width at half maximum of the first peak derived from polypyrrole was determined, and the shift amount from the position (reference position) of the second peak was also determined.

[0105] (c) Capacitance The initial capacitance (μF) of each solid electrolytic capacitor was measured at a frequency of 120 Hz using a four-terminal LCR meter in an environment of 20°C, and the average value for the 20 solid electrolytic capacitors was calculated.

[0106] Next, an accelerated test was performed by applying the rated voltage to the solid electrolytic capacitors for 2,000 hours in a 145°C environment. The capacitance after the accelerated test was then measured in a 20°C environment using the same procedure as for the initial capacitance, and the average value for 20 solid electrolytic capacitors was calculated. The capacitance change rate was calculated by subtracting the initial capacitance from the capacitance after the accelerated test, and was expressed as a ratio with the initial capacitance set to 100%. The capacitance change rate was a negative value, and a smaller value indicates lower heat resistance.

[0107] The evaluation results are shown in Table 1. A1 to A6 are examples, and B1 is a comparative example.

[0108] [Table 1]

[0109] As shown in Table 1, the solid electrolytic capacitors A1 to A6 have lower oxygen permeabilities in the solid electrolyte layer than the solid electrolytic capacitor B1, suppressing the decrease in capacitance. The oxygen permeabilities P1 of the solid electrolyte layers of the solid electrolytic capacitors A1 to A3 when heated at 230°C for 5 hours are approximately the same as those of the solid electrolytic capacitors A4 to A6, respectively. Therefore, it can be said that the oxygen permeabilities of the solid electrolytic capacitors A1 to A6 are kept low even after heat treatment. The full width at half maximum of the first peak in the Raman spectrum of the solid electrolyte layer of the solid electrolytic capacitors A1 to A6 is smaller than that of the solid electrolytic capacitor B1. Furthermore, the first peak in the solid electrolytic capacitors A1 to A6 is shifted from the reference position to a lower wavenumber. Therefore, it is believed that the film quality of the solid electrolyte layer of the solid electrolytic capacitors A1 to A6 is improved by improving the crystallinity due to the enhanced orientation of the conjugated polymer in the solid electrolyte layer and by making the copolymeric polymer energetically stable, thereby reducing the oxygen permeabilities P0 or P1. [Industrial Applicability]

[0110] According to the present disclosure, a solid electrolytic capacitor element and a solid electrolytic capacitor having excellent heat resistance are provided, and therefore the solid electrolytic capacitor element and the solid electrolytic capacitor can be used in a variety of applications requiring high reliability. [Explanation of symbols]

[0111] 1: solid electrolytic capacitor, 2: capacitor element, 3: resin outer casing, 4: anode terminal, 5: cathode terminal, 6: anode body, 7: dielectric layer, 8: cathode part, 9: solid electrolyte layer, 10: cathode lead layer, 11: carbon layer, 12: metal paste layer, 13: separation part, 14: adhesive layer

Claims

1. an anode body, a dielectric layer formed on a surface of the anode body, and a cathode portion covering at least a portion of the dielectric layer, the cathode portion includes a solid electrolyte layer (excluding a case where the solid electrolyte layer contains fluorocarbon) covering at least a portion of the dielectric layer; the solid electrolyte layer contains a conductive polymer component including a conjugated polymer, The oxygen permeability P of the solid electrolyte layer after heating at 230° C. for 5 hours １ But 1.0 cm ３ / m ２ A solid electrolytic capacitor element having a resistance of 24h·atm or less.

2. The oxygen permeability P of the solid electrolyte layer １ and the oxygen permeability P before heating ０ The difference between １ -P ０ ) is 0.3 cm ３ / m ２ The solid electrolytic capacitor element according to claim 1, wherein the temperature is 24 h·atm or less.

3. 3. The solid electrolytic capacitor element according to claim 1, wherein the solid electrolytic capacitor element is heat-treated at a temperature higher than 200°C and not higher than 300°C.

4. The solid electrolytic capacitor element according to claim 3 , wherein the heat treatment is carried out for one hour or more.

5. The solid electrolytic capacitor element according to any one of claims 1 to 4, wherein the conjugated polymer contains a monomer unit corresponding to at least one selected from the group consisting of a pyrrole compound, a thiophene compound, and an aniline compound.

6. In the Raman spectrum of the solid electrolyte layer, when a first peak attributed to the C═C stretching vibration derived from the conjugated polymer is fitted with a Lorentzian function, the full width at half maximum of the first peak is 35 cm －１ 80cm or more －１ The solid electrolytic capacitor element according to any one of claims 1 to 4, wherein:

7. the position of the first peak is shifted from the reference position to the low wavenumber side by 0.2% or more and 1% or less, 7. The solid electrolytic capacitor element according to claim 6, wherein the reference position is the position of a second peak, which is a second peak attributable to a C═C stretching vibration derived from the conjugated polymer, in a Raman spectrum of a solid electrolyte layer formed by bipolar electropolymerization and heated at 230° C. for 5 hours, when the second peak is fitted with a Lorentz function.

8. in the Raman spectrum of the solid electrolyte layer, when a first peak attributed to a C═C stretching vibration derived from the conjugated polymer is fitted with a Lorentzian function, the position of the first peak is shifted from a reference position to a lower wavenumber side by 0.2% or more and 1% or less; The solid electrolytic capacitor element according to any one of claims 1 to 4, wherein the reference position is the position of a second peak, which is attributed to a C=C stretching vibration derived from the conjugated polymer, when the second peak is fitted with a Lorentz function in a Raman spectrum of a solid electrolyte layer containing the conjugated polymer formed by bipolar electrolytic polymerization and heated at 230°C for 5 hours.

9. the conjugated polymer contains at least a monomer unit corresponding to pyrrole, The reference position is 1582 cm －１ 9. The solid electrolytic capacitor element according to claim 7, wherein

10. the conjugated polymer contains at least a monomer unit corresponding to pyrrole, The position of the first peak is 1566 cm －１ 1578cm or more －１ 7. The solid electrolytic capacitor element according to claim 6, wherein:

11. A solid electrolytic capacitor comprising at least one solid electrolytic capacitor element according to any one of claims 1 to 10.

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