TW202004796A - Electrolytic capacitor and method for producing same - Google Patents

Abstract

Provided is an electrolytic capacitor comprising: a negative electrode having a conductive substrate and a conductive polymer layer disposed on the surface of the conductive substrate; a positive electrode having a valve metal substrate and a dielectric layer disposed on the surface of the valve metal substrate, the positive electrode being disposed such that dielectric layer and the conductive polymer layer face each other with a space therebetween; and an ion-conductive electrolyte filling said space, wherein the conductive polymer layer is composed of a copolymer of 3,4-ethylenedioxythiophene and a compound represented by formula (I) (in the formula, the R's represent C1-10 linear or branched alkyls, x represents an integer of 1-4, and the respective R's may be identical or different when x represents an integer of at least 2).

Description

Electrolytic capacitor and its manufacturing method

The present invention relates to an electrolytic capacitor including a cathode having a conductive polymer layer capable of expressing redox capacity.

Generally speaking, an electrolytic capacitor having an ion-conducting electrolyte (including an electrolytic solution) has a structure in which an anode, a current collector cathode (virtual surface cathode), and a separator are contained in a sealed case. The surface of the valve metal foil such as tantalum and niobium is provided with an oxide film as a dielectric layer. The cathode is composed of the valve metal foil and the like. The separator is disposed between the anode and the cathode and retains the ions as the true cathode. Conductive electrolyte, and this electrolytic capacitor has been widely used in winding type, laminated type and other shapes of electrolytic capacitors.

Compared with plastic capacitors, mica capacitors, etc., this electrolytic capacitor has the advantages of small size and large capacity, and can increase the dielectric breakdown voltage of the capacitor by thickening the anode oxide film. However, if the anode oxide film is thickened, the capacity of the electrolytic capacitor will decrease, and a part of the advantages of small size and large capacity will be lost. Therefore, for the purpose of increasing the capacity without lowering the dielectric breakdown voltage of the electrolytic capacitor, studies have been conducted to increase the capacity of the cathode.

The applicant reported in Patent Document 1 (Japanese Patent Laid-Open No. 2017-188655) an electrolytic capacitor including: a cathode having a conductive substrate and a conductive polymer layer provided on the surface of the conductive substrate; An anode having a base composed of a valve metal and a dielectric layer composed of an oxide of the valve metal provided on the surface of the base, and the dielectric layer and the conductive polymer layer of the cathode It is arranged so as to face each other across a space; and, an ion conductive electrolyte, which is filled in the space; wherein, when a voltage is applied between the anode and the cathode, the conductive matrix of the cathode When electrons are supplied to the conductive polymer layer, the conductive polymer layer of the cathode in contact with the ion conductive electrolyte will exhibit a redox capacity, so the capacity of the cathode is significantly increased, so the capacity per unit volume of the electrolytic capacitor is significant Increase. In addition, the applicant conducted research on the basis of the capacitor disclosed in Patent Document 1, and in the PCT/JP2018/036871 application that was not published at the time of the application as the basis of the priority claim of the present case, reported that if the cathode is conductive When the contact resistance between the conductive substrate and the conductive polymer layer is 1 Ωcm ² or less, electrons can be supplied from the conductive substrate to the conductive polymer layer in an amount that can reliably exhibit redox capacity. The significance of the contact resistance between the conductive substrate and the conductive polymer layer in the cathode will be described below.

In addition, there are other documents that disclose an electrolytic capacitor provided with a cathode having a conductive polymer layer (refer to Patent Document 2 (Japanese Patent Laid-Open No. 3-112116)), Patent Document 3 (Japanese Patent Laid-Open No. Embodiment 2 of 7-283086), Embodiments 16 and 17 of Patent Document 4 (Japanese Patent Laid-Open No. 2000-269070). In the electrolytic capacitors of Patent Documents 2 to 4, it has not been confirmed that the redox capacity is expressed by the conductive polymer layer of the cathode. It is speculated that the supply of electrons to the conductive polymer layer in the electrolytic capacitors of these documents is not sufficient to express the redox capacity. [Prior Technical Literature] (Patent Literature)

Patent Literature 1: Japanese Patent Application Publication No. 2017-188655 Patent Document 2: Japanese Patent Laid-Open No. 3-112116 Patent Document 3: Japanese Patent Laid-Open No. 7-283086 Patent Document 4: Japanese Patent Laid-Open No. 2000-269070

[Problems to be solved by the invention] In the electrolytic capacitor disclosed in Patent Document 1, poly(3,4-ethylidene dioxythiophene) (hereinafter, 3,4-ethylidene dioxythiophene is represented as "EDOT" can be preferably used. A conductive polymer layer composed of poly(3,4-ethylidenethiophene) represented as "PEDOT"). The PEDOT layer shows high redox activity and is also excellent in heat resistance. Figure 1 shows the result obtained by performing cyclic voltammogram measurement by forming a carbon vapor-deposited film as an inorganic conductive layer on a natural oxide film of aluminum foil, and further forming a thickness of A 350-nm PEDOT layer was used to produce a cathode for electrolytic capacitors. Then, the cathode as the working electrode, the activated carbon electrode as the counter electrode, and the silver-silver chloride electrode as the reference electrode were introduced at a concentration of 20% by mass. The amidinium salt of phthalic acid is dissolved in an electrolyte obtained from γ-butyrolactone, and the cyclic voltammetry of the above cathode is measured. The measurement was carried out at room temperature for 5 cycles with a scanning speed of 100 mV/s in the range of -1.2 V to +0.2 V relative to the silver-silver chloride electrode. Figure 1 shows the cyclic voltammogram of the fifth cycle. In the cyclic voltammogram of Fig. 1, the oxidation wave indicating the doping of the PEDOT layer and the reduction wave indicating the dedoping are confirmed within a narrow range around -0.2V. This situation shows that rapid charging Discharge reaction. The electrolytic capacitor disclosed in Patent Document 1 is an electrolytic capacitor using this redox capacity. It can be known from the mechanism of the above-mentioned capacity appearance that the capacity of this electrolytic capacitor changes with the voltage value applied to the capacitor, but it is known that under normal use conditions, the capacity of the capacitor changes relatively little.

Therefore, although an electrolytic capacitor equipped with a cathode with a PEDOT layer can obtain a high capacity, after carrying out a high-temperature load test on this electrolytic capacitor under a DC voltage load and long-term storage at 125°C, confirm the capacitor capacity. As a result, the capacity of the capacitor after the test measured under the condition of the load bias voltage is lower than that before the test, especially in the high-frequency region. This change in the capacity of the capacitor will limit the use of the capacitor under high temperature conditions, so it should be avoided. Therefore, an object of the present invention is to provide an electrolytic capacitor based on the electrolytic capacitor disclosed in Patent Document 1 and a method for manufacturing the same, which suppresses a decrease in capacity when subjected to a load bias voltage after a high-temperature load test situation. [Technical means to solve the problem]

The inventors compared the cathode potential at the load bias voltage with respect to the capacitors before and after the high temperature load test in order to find the cause of the decrease in capacity after the load bias voltage after the high temperature load test. As a result, it was found that the cathode potential at the load bias voltage shifted to the negative side after the high-temperature load test. The reason for this displacement is considered to be the reduction (dedoping) of the PEDOT layer due to the continuous application of potential to the cathode under high temperature conditions. Moreover, the capacity drop after a high-temperature load test under load bias voltage is considered to be due to the fact that the cathode potential is shifted to the negative side due to the dedoping of the PEDOT layer, and the cathode potential under load bias voltage becomes The PEDOT layer is oxidized (doped) at a more negative potential, so the PEDOT layer becomes less prone to doping. Based on this speculation, if a conductive polymer layer is used for the electrolytic capacitor, the conductive polymer layer has a side that is more negative than the oxidation peak and the reduction peak of the cyclic voltammogram of the PEDOT layer shown in FIG. 1 The oxidation peak and the reduction peak can be expected to suppress the decrease in capacity when subjected to a load bias voltage after a high-temperature load test.

Therefore, the inventors first studied the use of a compound as the monomer for forming the conductive polymer layer, which compound has an electron-donating alkyl substituent bonded to the ethylidene group of EDOT. Fig. 2 shows that the cathode with the homopolymer layer (PEtEDOT layer) is used as the working electrode, and the result of the cyclic voltammogram is obtained under the same conditions as in the case of obtaining the cyclic voltammogram of Fig. 1. The object layer is a homopolymer layer in which an ethyl (Et) compound (EtEDOT) is bonded to the EDOT's ethylidene group, and the obtained results are compared with the cyclic voltammogram of the cathode with the PEDOT layer. The PEDOT layer shows an oxidation peak at a position of -0.168V relative to the silver-silver chloride electrode and a reduction peak at a position of -0.314V relative to the silver-silver chloride electrode, as indicated by the arrow in Figure 2, PEtEDOT The layer has an oxidation peak and a reduction peak on the more negative side than the PEDOT layer. However, using a cathode with a PEtEDOT layer to make an electrolytic capacitor and carrying out a high-temperature load test did not sufficiently improve the capacity at the load bias voltage after the test and the capacity drop at the load bias voltage before the test, and the low frequency region The situation in which the capacity of the capacitor decreases at the time becomes sharper (refer to Table 1).

However, it has been found that if a conductive polymer layer is formed by a copolymer of EDOT and a compound having an electron-donating alkyl group bonded to the ethylidene group of EDOT, this conductive polymer layer is unexpectedly less than PEDOT The more negative side of the layer has an oxidation peak and a reduction peak, and by using this conductive polymer layer, it is possible to suppress the capacity decrease when the load bias voltage after the high temperature load test is passed.

式(I)中，R表示碳數為1～10的直鏈狀或分枝狀的烷基，x表示1～4的整數，且當x表示2以上的整數時，各個R可相同亦可不同。以式(I)表示的化合物，相當於在EDOT的伸乙基上鍵結有x個取代基R之化合物。導電性高分子層，較佳是由選自由式(I)中的x表示1且R表示碳數為1～10的直鏈狀烷基的化合物所組成之群組中至少1種化合物與EDOT的共聚物所構成，特佳是由選自由式(I)中的x表示1且R表示碳數為2～4的直鏈狀烷基的化合物所組成之群組中至少1種化合物與EDOT的共聚物所構成。再者，為了顯現氧化還原容量，陰極的導電性高分子層需要與離子傳導性電解質直接接觸，但是陽極的介電質層可與離子傳導性電解質直接接觸，亦可經由其他導電性材料而與離子傳導性電解質間接地連接。Therefore, first, the present invention relates to an electrolytic capacitor including: a cathode having a conductive base and a conductive polymer layer provided on the surface of the conductive base; an anode having a base made of valve metal and A dielectric layer composed of the oxide of the valve metal provided on the surface of the substrate, and the dielectric layer and the conductive polymer layer of the cathode are arranged so as to face each other across a space ; And, an ion conductive electrolyte filled in the space; and, by applying a voltage between the anode and the cathode, the conductive polymer layer of the cathode in contact with the ion conductive electrolyte is oxidized Reduction capacity; the electrolytic capacitor is characterized in that the conductive polymer layer in the cathode is composed of a copolymer of EDOT and at least one compound selected from the group consisting of compounds represented by formula (I),

In formula (I), R represents a linear or branched alkyl group having 1 to 10 carbon atoms, x represents an integer of 1 to 4, and when x represents an integer of 2 or more, each R may be the same or different. The compound represented by formula (I) corresponds to a compound in which x substituents R are bonded to the ethylidene group of EDOT. The conductive polymer layer is preferably composed of at least one compound selected from the group consisting of a compound consisting of a linear alkyl group in which x represents 1 in Formula (I) and R represents a carbon number of 1 to 10 and EDOT It is composed of at least one compound selected from the group consisting of compounds represented by the formula (I) where x represents 1 and R represents a linear alkyl group having 2 to 4 carbon atoms. Of copolymers. In addition, in order to show the redox capacity, the conductive polymer layer of the cathode needs to be in direct contact with the ion conductive electrolyte, but the dielectric layer of the anode can be in direct contact with the ion conductive electrolyte, or can be The ion conductive electrolyte is indirectly connected.

Figures 3 to 8 show that the cathode with the copolymer layer of EDOT and EtEDOT (P(EDOT-EtEDOT) layer) is used as the working electrode, and the same conditions as in the case of obtaining the cyclic voltammogram of Figure 1 To obtain a cyclic voltammogram, and then compare the obtained results with the cyclic voltammogram for a cathode with a PEDOT layer. Figures 3 to 8 show the cyclic voltammograms of a cathode with a P(EDOT-EtEDOT) layer, which is a polymerization obtained by adjusting the molar ratio of EDOT and EtEDOT to the ratio shown in each figure Liquid. As shown by the arrows in Figures 3 to 8, the P(EDOT-EtEDOT) layer has oxidation peaks and reduction peaks on the more negative side than the PEDOT layer, and the molar ratio of EDOT and EtEDOT in the polymerization solution The difference is irrelevant. Furthermore, using a cathode with a P(EDOT-EtEDOT) layer to make an electrolytic capacitor and carrying out a high-temperature load test, the capacity at the load bias voltage after the test is improved compared to the capacity at the load bias voltage before the test. In particular, the situation in which the capacity of the capacitor decreases in the high-frequency region is significantly improved (see Table 1). Considering that the cathode with the PEDOT layer and the cathode with the PEtEDOT layer cannot suppress the decrease in the capacity at the load bias voltage after the test compared to the load bias voltage before the test, by having the copolymer layer, that is, P (EDOT-EtEDOT) layer of the cathode, surprisingly suppressed capacity reduction. In addition, FIGS. 3 to 8 show the results of using the P(EDOT-EtEDOT) layer as the cathode of the conductive polymer layer, but by using a compound represented by formula (I) other than EtEDOT and EDOT The copolymer can also achieve the same results.

The preferred form of the electrolytic capacitor of the present invention includes a cathode whose second cathode capacity in the following test is 80% or more of the first cathode capacity: the above cathode is introduced into the phthalic acid at a concentration of 20% by mass The amidinium salt is dissolved in an electrolyte obtained by γ-butyrolactone, and the first cathode capacity at 120 Hz at a potential of −0.4 V relative to the silver-silver chloride electrode at room temperature is measured, and then at the cathode Polarize in the direction from -0.4V until -1.0V, reverse the direction of polarization, and polarize in the anode direction until -0.6V, then measure the potential at -0.6V at 120Hz 2nd cathode capacity. Within this range, it is possible to more significantly improve the case where the capacity at the load bias voltage after the high-temperature load test is lower than the capacity at the load bias voltage before the test.

Another preferred form of the present invention includes a cathode. With reference to the results obtained by performing the following test, the potential of the reduction peak in the cyclic voltammogram of the fifth cycle of the cathode is a potential lower than -0.55V In this test, a cathode having the above-mentioned copolymer layer as a conductive polymer layer was introduced into the above-mentioned electrolyte, and at room temperature in the range of -1.2V to +0.2V relative to the silver-silver chloride electrode at 100mV /s scanning speed to measure the cyclic voltammetry of the cathode for 5 cycles; or with a cathode, the difference between the potential of the oxidation peak and the potential of the reduction peak in the cyclic voltammogram of the fifth cycle Within the range of 0.20 to 0.80V. Within this range, it is possible to more significantly improve the case where the capacity at the load bias voltage after the high-temperature load test is lower than the capacity at the load bias voltage before the test.

In the electrolytic capacitor of the present invention, if the contact resistance between the conductive substrate in the cathode and the conductive polymer layer provided on this surface is 3 Ωcm ² or less, by applying a voltage between the anode and the cathode of the electrolytic capacitor, An amount of electrons sufficient to cause the conductive polymer layer in contact with the ion-conducting electrolyte to exhibit redox capacity can be supplied, but if the contact resistance is 1 Ωcm ² or less, the redox capacity can be reliably exhibited, which is preferable.

The conductive substrate in the cathode may be composed of one conductive layer, or may be composed of a plurality of different conductive layers. When composed of multiple layers, the conductive layers can be in direct contact. Even if there is an insulating layer between the conductive layers, as long as part of the insulating layer is broken and there is conduction between the conductive layers, it can be used as a conductive substrate. Here, the contact resistance between the conductive substrate in the cathode and the conductive polymer layer means the value measured according to the method shown in FIG. 9. Fig. 9 (a) is a diagram showing the measurement method when the conductive substrate is composed of one conductive layer, and Fig. 9 (b) is a measurement showing the measurement when the conductive substrate is composed of two conductive layers Diagram of the method. Before measuring the contact resistance, first apply a carbon paste with a thickness of 5 to 10 μm (product model: DY-200L-2, manufactured by Toyobo Co., Ltd.) on the surface of the conductive polymer layer, and dry it at 150°C After 20 minutes, the copper foil was fixed to the surface of the carbon layer via a silver paste (product model: DW-250H-5, manufactured by Toyobo Co., Ltd.) and dried at 150°C for 20 minutes. Then, Fig. 9(a) is for performing an AC impedance measurement between the copper foil and the conductive substrate in the frequency range of 0.1 Hz to 100 kHz, and Fig. 9(b) is for the uncoated copper foil and the conductive substrate. The above-mentioned AC impedance measurement was performed between the layer (first layer) in contact with the conductive polymer layer. The value of the real part of the obtained Cole-Cole plot is the contact resistance between the conductive substrate and the conductive polymer layer. For example, when the first layer is aluminum foil, an aluminum oxide film is generally formed on the surface, but when a conductive layer as the second layer is formed on the surface of the aluminum oxide film, the measurement method shown in FIG. 9(b) is used . When the conductive substrate is composed of three or more conductive layers, the above-mentioned AC impedance measurement is performed between the copper foil and the conductive layer located farthest from the conductive polymer layer, and the obtained Kohl-Kehr The value of the real part of the figure is the contact resistance of the conductive substrate and the conductive polymer layer. The copper foil is connected to the conductive polymer layer via the carbon paste and the silver paste according to the above method.

Aluminum foil shows good corrosion resistance to the electrolyte, and therefore can be preferably used as a conductive substrate in the cathode. Generally speaking, although there is a natural aluminum oxide film on the surface of the aluminum foil, a conductive substrate composed of a plurality of conductive layers and directly contacting each conductive layer can be preferably obtained by: In the system, after the ions such as carrier gas collide with the natural alumina film to completely remove the above film, a protective conductive layer is formed on the surface of the aluminum foil for the purpose of improving water resistance or acid resistance, and further protect the conductivity here An inorganic conductive layer is formed on the layer. The conductive polymer layer is provided on the surface of the inorganic conductive layer of the substrate. The above-mentioned conductive substrate has excellent adhesion between the aluminum foil and the inorganic conductive layer and exhibits low contact resistance, so that the redox capacity generated by the conductive polymer layer of the cathode can be reliably exhibited.

Further, it is preferable that the conductive substrate is a substrate including an aluminum foil and an inorganic conductive layer, the aluminum foil includes an aluminum oxide film, the inorganic conductive layer is provided on the surface of the aluminum oxide film and includes an inorganic conductive material, and the inorganic The conductive layer is connected to the aluminum foil. At this time, the conductive polymer layer is provided on the surface of the inorganic conductive layer. The aluminum oxide film may be a natural oxide film or a chemical oxide film formed by chemical conversion treatment. In addition, in the process of providing the inorganic conductive layer on the surface of the aluminum oxide film, the inorganic conductive layer and the aluminum foil are electrically connected by breaking the aluminum oxide film, and the conductive substrate in the cathode can be brought into contact with the conductive polymer layer The resistance is adjusted to 1 Ωcm ² or less, and the redox capacity generated by the conductive polymer layer of the cathode can be reliably exhibited.

In addition, the present invention relates to a method of manufacturing an electrolytic capacitor, which includes: A cathode having a conductive substrate and a conductive polymer layer provided on the surface of the conductive substrate; An anode having a base composed of a valve metal and a dielectric layer composed of an oxide of the valve metal provided on the surface of the base, and the dielectric layer and the conductive polymer layer of the cathode It is arranged in a relative way across a space; and, An ion-conducting electrolyte, which is filled in the above space; Furthermore, by applying a voltage between the anode and the cathode, the conductive polymer layer of the cathode in contact with the ion conductive electrolyte exhibits a redox capacity; The manufacturing method of the electrolytic capacitor is characterized by including the following steps: Cathode formation step, which forms a conductive polymer layer on the surface of a conductive substrate to obtain a cathode for the electrolytic capacitor, the conductive polymer layer is selected from the group consisting of EDOT and the compound represented by the above formula (I) Constituted by a copolymer of at least one compound in the group; An anode forming step, which oxidizes the surface of the substrate composed of the valve metal to form a dielectric layer composed of the oxide of the valve metal to obtain an anode for the electrolytic capacitor; An electrolyte filling step, which opposes the conductive polymer layer of the cathode and the dielectric layer of the anode with a space therebetween, and fills the space with an ion conductive electrolyte; and, A redox capacity induction step of applying a voltage between the cathode and the anode, and supplying electrons to the conductive polymer layer from the conductive substrate of the cathode, thereby making the cathode conductive in contact with the ion conductive electrolyte The polymer layer exhibits redox capacity. By this method, it is possible to obtain an electrolytic capacitor which improves the situation where the capacity at the load bias voltage after the high temperature load test is lower than the capacity at the load bias voltage before the test.

In the above cathode forming step, the conductive polymer layer on the conductive substrate of the cathode may be formed by electrolytic polymerization, or may be formed by chemical polymerization, and also by The dispersion liquid of particles is formed by coating on the surface of the above conductive substrate, preferably by electrolytic polymerization. By electrolytic polymerization, a conductive polymer layer excellent in mechanical strength can be formed from a small amount of monomers on the surface of the conductive substrate in a short time, and a thin, dense, and uniform conductive polymer layer can be obtained. In electrolytic polymerization, it is preferable to use an EDOT containing a molar ratio in the range of 19:1 to 1:7, preferably 7:1 to 1:3, and a compound selected from the group consisting of compounds represented by the above formula (I) Electrolytic polymerization solution of at least one compound in the group. Within this range, a conductive polymer layer can be preferably obtained, which can significantly improve the electrolytic capacitor in the case where the capacity at the load bias voltage after the high-temperature load test is lower than the capacity at the load bias voltage before the test. [Efficacy of invention]

An electrolytic capacitor provided with a cathode having a conductive polymer layer capable of expressing redox capacity, if the electrolytic capacitor is composed of EDOT and selected from the group consisting of compounds represented by the above formula (I) If the copolymer of at least one compound constitutes the conductive polymer layer, the capacity at the time of the load bias voltage after the high-temperature load test can be reduced compared to the capacity at the time of the load bias voltage before the test.

式(I)中，R表示碳數為1～10的直鏈狀或分枝狀的烷基，x表示1～4的整數，且當x表示2以上的整數時，各個R可相同亦可不同。藉由此導電性高分子層，能夠改善高溫負載試驗後的負載偏電壓時的容量比試驗前的負載偏電壓時的容量下降的情形。能夠藉由以下所示的陰極形成步驟、陽極形成步驟、電解質填充步驟、及氧化還原容量誘發步驟，來製造本發明的電解電容器。以下，詳細說明各步驟。The electrolytic capacitor of the present invention is an electrolytic capacitor comprising: a cathode having a conductive substrate and a conductive polymer layer provided on the surface of the conductive substrate; an anode having a substrate made of valve metal and A dielectric layer composed of the oxide of the valve metal provided on the surface of the substrate, and the dielectric layer and the conductive polymer layer of the cathode are arranged so as to face each other across a space ; And, an ion conductive electrolyte filled in the space; and, by applying a voltage between the anode and the cathode, the conductive polymer layer of the cathode in contact with the ion conductive electrolyte is oxidized Reduction capacity; the electrolytic capacitor is characterized in that the conductive polymer layer in the cathode is composed of EDOT and at least one compound selected from the group consisting of compounds represented by formula (I) EDOT consists of a copolymer of at least one compound in the group consisting of compounds with x substituents R bonded to the ethylidene group,

In formula (I), R represents a linear or branched alkyl group having 1 to 10 carbon atoms, x represents an integer of 1 to 4, and when x represents an integer of 2 or more, each R may be the same or different. With this conductive polymer layer, it is possible to improve the situation where the capacity at the time of the load bias voltage after the high-temperature load test is lower than the capacity at the time of the load bias voltage before the test. The electrolytic capacitor of the present invention can be manufactured by the cathode forming step, anode forming step, electrolyte filling step, and redox capacity induction step shown below. Hereinafter, each step will be described in detail.

(1) Cathode formation step The cathode in the electrolytic capacitor of the present invention has a conductive substrate and a conductive polymer layer provided on the surface of the conductive substrate. As the conductive substrate, as long as sufficient electrons can be supplied to allow the conductive polymer layer to sufficiently exhibit the redox capacity, the substrate that functions as a current collector can be used without particular limitation. A cathode forming step, the resistance of the conductive substrate can be used is preferably ² or less 25Ωcm, is preferably 6Ωcm ² or less, particularly preferably less 0.25Ωcm ² is a conductive substrate. Here, the resistance of the conductive substrate means a value measured by the same method as the above-mentioned method for measuring the contact resistance of the conductive substrate and the conductive polymer layer. That is, apply a carbon paste (product model: DY-200L-2, manufactured by Toyobo Co., Ltd.) with a thickness of 5 to 10 μm on the surface of the conductive substrate on which the conductive polymer layer is to be formed, and apply it at 150° C. After drying for 20 minutes, the copper foil was fixed to the surface of the carbon layer via a silver paste (product model: DW-250H-5, manufactured by Toyobo Co., Ltd.), and dried at 150°C for 20 minutes. Then, an AC impedance measurement is performed between the copper foil and the conductive substrate in the frequency range of 0.1 Hz to 100 kHz. The value of the real part of the obtained Cole-Cole diagram is the resistance of the conductive substrate.

Such a conductive substrate may be composed of one conductive layer or a plurality of different conductive layers. When composed of multiple layers, the conductive layers can be in direct contact. Even if there is an insulating layer between the conductive layers, as long as part of the insulating layer is broken and there is conduction between the conductive layers, it can be used as a conductive substrate. For example, the following foils used as cathodes in conventional electrolytic capacitors can be used as conductive substrates: foils of valve metals such as aluminum, tantalum, niobium, titanium, and zirconium; or, by applying chemical or electrochemical methods to these valve metals After the etching process to increase the surface area of these valve metal foils; also can make aluminum-copper alloy and other alloys into a conductive substrate. On the surface of the valve metal foil, there is generally a natural oxide film, but by removing the natural oxide film completely, one or more inorganic conductive layers containing inorganic conductive materials can be formed on the surface of the valve metal foil to obtain The conductive substrate is composed of a conductive layer of each layer and each conductive layer directly contacts. In addition, even on the surface of the valve metal foil, in addition to the existence of a natural oxide film, there is also a chemical oxide film formed by the use of ammonium borate aqueous solution, ammonium adipate aqueous solution, ammonium phosphate aqueous solution, etc. The chemical conversion treatment can still be used by making a conductive substrate by: In the process of providing an inorganic conductive layer containing an inorganic conductive material on the surface of the aluminum oxide film, a part of the aluminum oxide film is destroyed to make The conductive layer is in conduction with the valve metal foil. The type of inorganic conductive material used to form the inorganic conductive layer and the method of forming the inorganic conductive layer are not particularly limited as long as sufficient electrons can be supplied to allow the conductive polymer layer to exhibit redox capacity. For example, it is possible to destroy part of the oxide film in the following process to connect the inorganic conductive layer to the valve metal foil: by using vacuum evaporation, sputtering, ion plating, coating, electroplating, electroless plating, etc., the carbon , Titanium, platinum, gold, silver, cobalt, nickel, iron and other inorganic conductive materials are laminated on the oxide film to provide an inorganic conductive layer.

As the valve metal foil, aluminum foil or aluminum foil subjected to etching treatment as necessary shows good corrosion resistance to the electrolytic solution, which is preferable. When aluminum foil is used, there is generally a natural alumina coating, but it is preferable to completely remove the coating by conflicting ions such as carrier gas and natural alumina coating in a vacuum system, in order to improve water resistance or acid resistance For the purpose of protection, a protective conductive layer is formed on the surface of the aluminum foil, and an inorganic conductive layer is further formed on the protective conductive layer, thereby obtaining a conductive substrate composed of the conductive layer and each conductive layer directly contacting; and, even if it has The natural aluminum oxide film or aluminum foil converted into aluminum oxide film is preferably: as described above, an inorganic conductive layer is provided on the aluminum oxide film, and part of the aluminum oxide film is destroyed in the process to make the inorganic conductive layer communicate with the aluminum foil . When a titanium vapor-deposited film is used as the inorganic conductive layer, it can contain atoms in the surrounding atmosphere during vapor deposition, for example, it can contain nitrogen, carbon, or the like to form a titanium nitride vapor-deposited film and a titanium carbide vapor-deposited film. If the above-mentioned inorganic conductive layer is a layer containing at least one inorganic conductive material selected from the group consisting of carbon, titanium, titanium nitride, titanium carbide, and nickel, a cathode with excellent durability can be obtained, so it is preferable . In addition, among them, a titanium carbide vapor-deposited film, a carbon vapor-deposited film, and the like can obtain a polymer film that exhibits stable characteristics in the electrolytic polymerization shown below, and is therefore preferable; the carbon coating layer has excellent productivity, Therefore it is better.

On the surface of the conductive substrate, a conductive polymer layer is provided. When the inorganic conductive layer is provided, a conductive polymer layer is provided on the surface of the inorganic conductive layer. The conductive polymer layer may be an electrolytic polymer film or a chemical polymer film, or may be formed using a dispersion liquid that contains at least particles of a conductive polymer and a dispersion medium.

The formation of an electrolytic polymer film can be carried out by introducing the above-mentioned conductive substrate and the counter electrode into a polymerization solution, and applying a voltage between the conductive substrate and the counter electrode. The polymerization solution contains at least a monomer and a support Electrolytes and solvents. As the counter electrode, a plate or mesh of platinum, nickel, steel, or the like can be used. In the process of electrolytic polymerization, the conductive polymer layer contains anions released from the supporting electrolyte as a dopant.

As a solvent of the polymerization solution for electrolytic polymerization, a solvent that can dissolve a desired amount of monomers and a supporting electrolyte without adversely affecting electrolytic polymerization can be used without particular limitation. Examples include water, methanol, ethanol, isopropanol, butanol, ethylene glycol, acetonitrile, butyronitrile, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, and γ-butyrolene. Ester, methyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, ethyl carbonate, propyl carbonate, nitromethane, nitrobenzene, cispyridine, dimethyl cyproterone. These solvents may be used alone or in combination of two or more. If a solvent containing water in an amount of 80% by mass or more of the entire solvent is used, especially a solvent composed only of water, a dense and stable electrolytic polymerization membrane can be obtained, which is preferable.

The polymerization solution for electrolytic polymerization contains EDOT as a monomer and x (x represents an integer of 1 to 4) substituent R (R represents carbon) bonded to the ethylidene group of EDOT represented by the above formula (I) The number is 1-10 linear or branched alkyl compounds. The compound represented by the above formula (I) contained in the polymerization solution together with EDOT may be one kind of compound or two or more kinds of compounds. Examples of the substituent R include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, secondary butyl, tertiary butyl, n-pentyl, 1-methyl Butyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-bis Methylpropyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl. When x represents an integer of 2 or more, each R may be the same or different. It is preferred that the polymerization solution contains a compound selected from the group consisting of a compound consisting of a linear alkyl group with x representing 1 in formula (I) and R representing a carbon number of 1 to 10 and EDOT, particularly preferably polymerization The liquid contains a compound selected from the group consisting of a compound composed of a compound in which x in Formula (I) represents 1 and R represents a linear alkyl group having 2 to 4 carbon atoms, and EDOT.

As the supporting electrolyte contained in the polymerization solution for electrolytic polymerization, a compound capable of releasing a dopant contained in a conventional conductive polymer can be used without particular limitation. Examples include: boric acid, nitric acid, phosphoric acid, phosphotungstic acid, phosphomolybdic acid and other inorganic acids; acetic acid, oxalic acid, citric acid, aconitic acid, tartaric acid, squaric acid, rose palmitic acid, crotonic acid, salicylic acid Organic acids such as acids; and, methanesulfonic acid, dodecylsulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, 1,2-dihydroxy-3,5-benzenedi Sulfonic acid, naphthalene sulfonic acid, naphthalene disulfonic acid, propyl naphthalene sulfonic acid, butyl naphthalene sulfonic acid and other sulfonic acids; and, salts of these. In addition, the following substances can also be used as supporting electrolytes: polycarboxylic acids such as polyacrylic acid, polymethacrylic acid, and polymaleic acid; polysulfonic acids such as polystyrenesulfonic acid and polyvinylsulfonic acid; and salt.

(式(II)、(III)中，m表示1～8的整數，較佳是表示1～4的整數，特佳是表示2；n表示1～8的整數，較佳是表示1～4的整數，特佳是表示2；o表示2或3的整數)Furthermore, the following substances can also be used as supporting electrolytes: borodisalicylic acid, borodioxalic acid, borodimalonic acid, borodisuccinic acid, borodiadipic acid, borodimaleic acid, borodiglycolic acid, Borodilactic acid, boron dihydroxyisobutyric acid, boron dimalic acid, boron ditartaric acid, boron dicitric acid, boron diphthalic acid, boron dihydroxybenzoic acid, boric bismandelic acid, boron di(diphenylethanol Acid) boron complexes such as sulfonimides represented by formula (II) or formula (III); and salts of these.

(In formulas (II) and (III), m represents an integer of 1-8, preferably an integer of 1-4, particularly preferably 2; n represents an integer of 1-8, preferably 1-4 ，Integer means 2; o means 2 or 3)

Examples of salts include alkali metal salts such as lithium salts, sodium salts, and potassium salts; alkyl ammonium salts such as ammonium salts, ethyl ammonium salts, and butyl ammonium salts; and diethyl ammonium salts and dibutyl ammonium salts. Dialkylammonium salts; triethylammonium salts, tributylammonium salts and other trialkylammonium salts; tetraethylammonium salts, tetrabutylammonium salts and other tetraalkylammonium salts.

These supporting electrolytes can be used alone or in combination of two or more types, and depending on the type of supporting electrolyte, they can be used in an amount less than the saturation solubility with respect to the polymerization solution, and a current sufficient for electrolytic polymerization can be obtained Is preferably used at a concentration of 10 millimoles or more relative to 1 liter of the polymerization solution.

If an electrolytic polymerization solution is used, it is a solvent containing borodisalicylic acid and its salts as a supporting electrolyte dissolved in a solvent containing a large amount of water, preferably a solvent containing water in an amount of 80% by mass, particularly preferably only In a solvent composed of water, a conductive polymer layer containing boron disalicylate ions as a dopant can improve the frequency dependence of the capacitor capacity, and can be obtained under high frequency conditions. High capacity is therefore better. Also, it is known that if an electrolytic polymerization solution is used, it is a solvent containing boron disalicylic acid and its salt as a supporting electrolyte dissolved in a solvent containing a large amount of water, preferably a water containing 80% by mass, Preferably, in a solvent composed of only water, an anionic surfactant is further coexisted, and the surfactant is used to make the above monomers soluble or emulsified in the above solvent, which can further improve the frequency of the capacitor capacity Interdependence. Examples of anionic surfactants that can be used include fatty acid salt-type surfactants, such as sodium laurate, sodium palmitate, and sodium stearate; amino acid-type surfactants, such as lauryl glutamate Sodium, sodium lauryl aspartate, and sodium lauryl methyl alanine; sulfate-based surfactants, such as alkyl sulfates such as sodium lauryl sulfate and sodium myristyl sulfate, polyoxygenated Alkyl ether sulfates such as sodium lauryl ether sulfate and polyoxyethylene alkyl ether sodium sulfate; sulfonic acid surfactants, such as alkane sulfonates such as sodium decane sulfonate and sodium dodecane sulfonate, Alkylbenzenesulfonates such as sodium octylbenzenesulfonate and sodium dodecylbenzenesulfonate, alkylnaphthalenesulfonates such as sodium isopropylnaphthalenesulfonate and sodium butylnaphthalenesulfonate, polystyrene Polymer sulfonates such as sodium sulfonate, olefin sulfonates such as sodium tetradecene sulfonate, and sulfo fatty acid ester salts such as sodium dioctyl sulfosuccinate; and, alkyl phosphate type interface activity Agents, such as sodium lauryl phosphate, sodium myristyl phosphate and polyoxyethylene sodium lauryl phosphate. The above-mentioned anionic surfactants may be used alone or as a mixture of two or more kinds, and may be used in an amount sufficient to solubilize or emulsify a desired amount of monomers. If the anionic surfactant is a sulfonic acid type surfactant and/or a sulfate type surfactant, an electrolytic capacitor having particularly excellent frequency characteristics can be obtained, which is preferable.

Electrolytic polymerization can be carried out by any of the constant potential method, constant current method, and potential scanning method. When based on the constant-potential method, depending on the type of monomer, it is preferably 1.0 to 1.5 V relative to a saturated calomel electrode (saturated calomel electrode); when based on the constant-current method, depending on the type of monomer, A current value of 1 to 10000 μA/cm ² is preferred; when according to the potential scanning method, depending on the type of monomer, it is preferable to scan at a speed of 5 to 200 mV/sec relative to a saturated calomel electrode at 0 to 1.5 The range of V. The polymerization temperature is not strictly limited, and is generally in the range of 10 to 60°C. There is no strict limit to the polymerization time, but it is generally in the range of 1 minute to 10 hours.

The formation of a chemically polymerized film can be carried out according to the following method: prepare a solution obtained by dissolving both the monomer and the oxidizing agent in a solvent, and apply this by brush coating, drop coating, dip coating, spray coating, etc. The liquid is applied to the surface of the above-mentioned conductive substrate, and then dried; or, the liquid prepared by dissolving the monomer in the solvent and the liquid obtained by dissolving the oxidizing agent in the solvent are applied by brushing and dropping These liquids are alternately applied to the surface of the conductive substrate by cloth, dip coating, spray coating, etc., and then dried. As the solvent, for example, water, methanol, ethanol, isopropanol, butanol, ethylene glycol, acetonitrile, butyronitrile, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, γ-butan Lactone, methyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, ethyl carbonate, propyl carbonate, nitromethane, nitrobenzene, cispyridine, dimethyl cyproterone. These solvents may be used alone or in combination of two or more. As a monomer, EDOT can be used in combination with x (x represents an integer of 1 to 4) substituents R (R represents a carbon number of 1 to 10) bonded to the ethylidene group of EDOT represented by the above formula (I) Straight-chain or branched alkyl) compounds. As the compound represented by the above formula (I) used in combination with EDOT, one compound may be used, or two or more compounds may be used. In the chemical polymerization, it is preferable to use a compound selected from the group consisting of compounds represented by x in Formula (I) and R representing a linear alkyl group having 1 to 10 carbon atoms in combination with EDOT, particularly preferred It is a compound selected from the group consisting of compounds in which x in Formula (I) represents 1 and R represents a linear alkyl group having 2 to 4 carbon atoms and EDOT. As an oxidizing agent, ferric iron salts such as iron (III) p-toluenesulfonate, iron (III) naphthalenesulfonate, and iron (III) anthraquinonesulfonate can be used; or, ammonium peroxodisulfate, sodium peroxodisulfate Persulfate, etc.; a single compound may be used, or two or more compounds may be used. The polymerization temperature is not strictly limited, and is generally in the range of 0 to 200°C. There is no strict limit to the polymerization time, but it is generally in the range of 1 minute to 10 hours.

Furthermore, a conductive polymer layer can also be formed by applying a dispersion liquid containing at least particles of a conductive polymer and a dispersion medium to the surface of the above-mentioned conductive substrate by means such as coating and dropping And dried. As the dispersion medium in the above dispersion liquid, for example, water, methanol, ethanol, isopropanol, butanol, ethylene glycol, acetonitrile, butyronitrile, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-bis Oxane, γ-butyrolactone, methyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, ethyl carbonate, propyl carbonate, nitromethane, nitrobenzene, cyclobutane, di Methyl cyclobutane; water is preferably used as a dispersion medium. The above-mentioned dispersion liquid can be obtained, for example, by adding EDOT as a monomer in water and the ethyl group of EDOT represented by the above formula (I) bonded with x (x represents an integer of 1 to 4) ) A compound with a substituent R (R represents a linear or branched alkyl group having 1 to 10 carbon atoms), an acid or salt thereof capable of releasing a dopant, and an oxidizing agent, and is stirred until chemical oxidation polymerization Until the end, after using ultrafiltration, cation exchange and anion exchange to remove oxidants and residual monomers, perform dispersion treatments such as ultrasonic dispersion treatment, high-speed fluid dispersion treatment, and high-pressure dispersion treatment as needed . In addition, it can be obtained by adding EDOT as a monomer in water and the substitution of x (x represents an integer of 1 to 4) on the ethylidene group of EDOT represented by the above formula (I) The compound of the radical R (R represents a linear or branched alkyl group having 1 to 10 carbon atoms) and the acid or its salt capable of releasing the dopant, and the electrolytic oxidation polymerization is carried out while stirring, and then, Refining means such as ultrafiltration, cation exchange and anion exchange are used to remove residual monomers, and if necessary, dispersion treatments such as ultrasonic dispersion treatment, high-speed fluid dispersion treatment, and high-pressure dispersion treatment are carried out. Further, it can be obtained by filtering the liquid obtained by the above-mentioned chemical oxidation polymerization method or electrolytic polymerization method to separate the aggregates, and after sufficiently washing, adding water, and performing ultrasonic dispersion treatment, high-speed fluid Dispersion processing such as dispersion processing and high-pressure dispersion processing. The content of the conductive polymer particles in the dispersion is generally in the range of 1.0 to 3.0% by mass, and preferably in the range of 1.5% to 2.0% by mass.

By using a cathode with a thinner conductive polymer layer, the size of the cathode can be reduced, and even the capacity per unit volume of the capacitor can be increased. The thickness of the conductive polymer layer of the cathode is preferably in the range of 200 to 2450 nm. If the thickness of the conductive polymer layer is less than 200 nm, it is considered that the high-temperature durability tends to decrease. In addition, if the thickness of the conductive polymer layer is thicker than 2450 nm, the temperature dependence of the capacity becomes larger, and it becomes difficult to The miniaturization of electrolytic capacitors contributes.

The conductive polymer layer of the cathode is preferably formed by electrolytic polymerization. By electrolytic polymerization, a conductive polymer layer having excellent mechanical strength can be formed from a small amount of monomers on the surface of the conductive substrate in a short time, and a thin, dense and uniform conductive polymer can be obtained Floor. In electrolytic polymerization, it is preferable to use an EDOT containing a molar ratio in the range of 19:1 to 1:7, preferably 7:1 to 1:3 and a compound selected from the group represented by the above formula (I) A polymerization solution of at least one compound in the group. When two or more compounds represented by formula (I) are used, the ratio of the molar amount of EDOT to the total molar amount of two or more compounds represented by formula (I) is from 19:1 to 1:7. It is preferably in the range of 7:1 to 1:3. Within this range, a conductive polymer layer can be preferably obtained, which can significantly improve the electrolytic capacitor in the case where the capacity at the load bias voltage after the high-temperature load test is lower than the capacity at the load bias voltage before the test.

The preferred form of the electrolytic capacitor of the present invention is provided with a cathode. According to the results of the following test, the capacity of the second cathode of the cathode is 80% or more of the capacity of the first cathode. After forming a conductive polymer layer on the surface of the substrate to obtain a cathode, the obtained cathode was introduced into an electrolytic solution obtained by dissolving the amidinium phthalate in γ-butyrolactone at a concentration of 20% by mass, and The first cathode capacity at 120 Hz at a potential of -0.4 V relative to the silver-silver chloride electrode was measured at room temperature, and then polarized in the cathode direction from -0.4 V to -1.0 V, and then reversed In the direction of polarization, polarize in the direction of the anode until -0.6V, and then measure the second cathode capacity at 120Hz at a potential of -0.6V. Within this range, it is possible to more significantly improve the case where the capacity at the load bias voltage after the high-temperature load test is lower than the capacity at the load bias voltage before the test.

Another preferred form of the electrolytic capacitor of the present invention includes a cathode. With reference to the results obtained by performing the following test, the potential of the reduction peak in the cyclic voltammogram of the fifth cycle of the cathode is more than -0.55V Low potential, this test is to form a conductive polymer layer on the surface of the conductive substrate through the above steps to obtain a cathode, and then introduce the obtained electrode into the above electrolyte, and at room temperature relative to silver- Silver chloride electrode-Measure the cyclic voltammetry of the above cathode for 5 cycles at a scanning speed of 100mV/s within the range of -1.2V to +0.2V; or have a cathode and the cyclic voltammetry of the 5th cycle The difference between the potential of the oxidation peak and the reduction peak in the figure is in the range of 0.20 to 0.80V. Within this range, it is possible to more significantly improve the case where the capacity at the load bias voltage after the high-temperature load test is lower than the capacity at the load bias voltage before the test.

In the electrolytic capacitor of the present invention, if the contact resistance between the conductive substrate in the cathode and the conductive polymer layer provided on this surface is 3 Ωcm ² or less, by applying a voltage between the anode and the cathode of the electrolytic capacitor, It is possible to supply an amount of electrons sufficient to cause the conductive polymer layer in contact with the ion-conducting electrolyte to exhibit redox capacity, but if the contact resistance is 1 Ωcm ² or less, the redox capacity can be reliably exhibited, which is preferable; Particularly preferably, the contact resistance is 0.06 Ωcm ² or less. It is known that the lower the contact resistance, the better the frequency characteristics of the electrolytic capacitor obtained by the present invention. The above-mentioned contact resistance is measured by the method described with reference to FIG. 9 after forming the conductive polymer layer on the surface of the conductive substrate by the above steps.

(2) Anode formation step The anode in the electrolytic capacitor of the present invention has a base composed of valve metals such as aluminum, tantalum, niobium, titanium, and zirconium, and a dielectric composed of oxides of the above valve metals provided on the surface of the base Floor. The substrate used for the anode is preferably a substrate obtained by performing chemical or electrochemical etching treatment on the valve metal foil according to a known method to increase the surface area, particularly preferably an aluminum foil subjected to etching treatment. The dielectric layer on the surface of the substrate can be formed according to the following well-known method: the substrate is subjected to chemical conversion treatment using chemical liquids such as an aqueous solution of ammonium borate, an aqueous solution of ammonium adipate, and an aqueous solution of ammonium phosphate.

(3) Electrolyte filling step In this step, the cathode obtained in the cathode forming step and the anode obtained in the anode forming step are arranged in such a manner that the conductive polymer layer of the cathode and the dielectric layer of the anode are opposed to each other across a space. After the anode is combined, the space is filled with an ion conductive electrolyte. The cathode has a conductive substrate and a conductive polymer layer provided on the surface of the conductive substrate. The anode has a substrate made of valve metal and A dielectric layer composed of the above-mentioned valve metal oxide is provided on the surface of the substrate.

As the ion conductive electrolyte, a known ion conductive electrolyte that does not have electron conductivity can be used without particular limitation. First, it is possible to use electrolytes conventionally used for electrolytic capacitors, for example, the following electrolytes: benzoate, butyrate, phthalate, isophthalate, terephthalate, Salicylate, tartrate, oxalate, malonate, malate, glutarate, adipic acid, azelate, maleate, fumarate, citrate, homobenzene Tetraformate, trimellitate, 1,6-decane diformate, formate, acetate, glycolate, lactate, 1-naphthoate, amygdalate, citraconic acid Salt, 2,4-dihydroxybenzoate, 2,5-dihydroxybenzoate, 2,6-dihydroxybenzoate, boron disalicylate, boron dioxalate, boron Dimalonic acid salts and other solutes, soluble in γ-butyrolactone, δ-valerolactone, ethylene glycol, diethylene glycol, propylene glycol, methylcellulose, ethylene glycol monomethyl ether, ciprool , Propyl carbonate, acetonitrile, water and other solvents in the electrolyte. Examples of the salts include amidinium salts, phosphonium salts, ammonium salts, amine salts, and alkali metal salts. The solute is preferably a carboxylate. If a large amount of carboxylate is contained, the redox capacity generated by the conductive polymer layer of the cathode increases. The content of the carboxylate in the electrolyte is preferably at least a concentration of 0.1M, and at most the saturated dissolved amount in the electrolyte. In particular, the amidinium salt is preferable because it can significantly increase the redox capacity generated by the conductive polymer layer of the cathode. Examples of amidinium salts include 1,3-dimethylimidazolium salt, 1-ethyl-3-methylimidazolium salt, 1-methyl-2,3-dimethylimidazolium salt, etc. Imidazolium salt; 1,2,3,4-tetramethylimidazolium salt, 1,3-dimethyl-2,4-diethylimidazolium salt, 1,2-dimethyl-3, 4-diethylimidazolium salts and other imidazolinium salts; 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium salts, 1,2,3-trimethyl-1,4 , 5,6-tetrahydropyrimidinium salt, 1,3-dimethyl-1,4-dihydropyrimidinium salt and other pyrimidinium salts; formamidine salts, acetamidine salts, benzamidine salts and other chains Amidinium salt. The solvent of the electrolyte may be a single compound or a mixture of two or more types; the solute may also be a single compound or a mixture of two or more types.

These electrolytes may contain well-known additives in addition to the above-mentioned solvents and solutes. For example, for the purpose of improving the voltage resistance of capacitors, phosphoric acid compounds such as phosphoric acid and phosphoric acid esters; boric acid compounds such as boric acid; mannan Sugar alcohols such as sugar alcohols; complex compounds of boric acid and sugar alcohols; polyoxyalkylene polyols such as polyethylene glycol, polyglycerol, polypropylene glycol, etc.; further, especially for the purpose of absorbing hydrogen that is generated rapidly at high temperatures, May contain: nitrophenol, nitrobenzoic acid, nitroanisole, nitrobenzyl alcohol and other nitro compounds. In addition, these electrolytes may contain a gelling agent. Furthermore, a normal-temperature molten salt (ionic liquid) can be used as the ion-conducting electrolyte.

This step can be performed by, for example, impregnating the above-mentioned electrolyte or ionic liquid in a capacitor element that is formed by interposing the separator and the conductive polymer layer of the cathode and the anode After the electrode layer is opposed to each other, the band-shaped cathode and the anode are stacked, and then wound. In addition, this step can be performed by impregnating the electrolytic solution or ionic liquid in a capacitor element formed by a conductive polymer layer of the cathode and the anode through a separator and a separator The cathode and the anode of the desired shape are laminated so that the dielectric layer faces each other. The above electrolyte or ionic liquid can also be impregnated into the capacitor element, the capacitor element is alternately stacked in a manner that the separator is sandwiched and the conductive polymer layer of the cathode faces the dielectric layer of the anode Group of cathode and anode. As the separator, a woven or non-woven fabric composed of cellulose-based fibers can be used, for example: Manila paper, kraft paper, esparto paper, hemp paper, cotton paper, rayon, and a mixture of these Papermaking; or woven or non-woven fabrics composed of the following resins: polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and derivatives of these, etc. Polyester resin; Polytetrafluoroethylene resin; Polyvinylidene fluoride resin; Vinylon (vinylon) resin; Aliphatic polyamide, semi-aromatic polyamide, fully aromatic polyamide and other polyamide Amine resin; Polyimide resin; Polyethylene resin, polypropylene resin, trimethylpentene resin, polyphenylene sulfide resin, acrylic resin, etc.; and can use cellophane, cellophane and Manila paper, kraft paper Mixed paper, etc. The impregnation of the electrolyte or ionic liquid can be carried out after the capacitor element is housed in a package case having an opening. If an electrolytic solution containing a gelling agent is used, the electrolytic solution can be gelled by heating after impregnating the electrolytic solution in the capacitor element.

In addition, this step can be performed by filling the space formed by the spacer of the capacitor element with an ion-conducting electrolyte, the capacitor element is formed by: interposing an insulating spacer The conductive polymer layer of the cathode is opposed to the dielectric layer of the anode. In the case of this form, as the ion conductive electrolyte, in addition to the above electrolyte or ionic liquid, a gel-like electrolyte that allows polyvinylidene fluoride, polyacrylonitrile, etc. to absorb the above electrolyte can also be used Obtained; or, a solid electrolyte, which is composed of a compound of the above salts and a polymer compound such as polyethylene oxide, polymethacrylate, polyacrylate, and the like. A gel or solid electrolyte can be laminated on the conductive polymer layer of the cathode, and then the anode can be laminated on this electrolyte by contacting the dielectric layer.

In the present invention, the conductive polymer layer of the cathode needs to be in direct contact with the ion conductive electrolyte, and the conductive polymer layer of the cathode does not directly contact with the anode, but is connected to the anode (conductive) via the ion conductive electrolyte, but The dielectric layer of the anode may be in direct contact with the ion conductive electrolyte, or may be indirectly connected to the ion conductive electrolyte through other conductive materials. Examples of suitable other conductive materials include conductive polymer layers. This conductive polymer layer can be formed on the surface of the dielectric layer of the anode according to the electrolytic polymerization method or the chemical polymerization method after the anode is formed in the above anode forming step, and can also be formed by the following method: A dispersion liquid containing at least conductive polymer particles and a dispersion medium is coated on the surface of the anode dielectric layer and dried. The conductive polymer layer of the anode is not limited to the conductive polymer layer formed of the copolymer of the EDOT and the compound represented by formula (I), and a known conductive polymer layer such as a PEDOT layer can also be used. When the conductive polymer layer is provided adjacent to the dielectric layer of the anode, as long as the conductive layer and the conductive polymer layer of the cathode are arranged and combined in a manner facing each other across a space, It is sufficient to fill the space with an ion conductive electrolyte.

(4) Redox capacity induction step If a voltage is applied between the anode and the cathode of the sealed capacitor element housed in the outer casing, and electrons are supplied to the conductive polymer layer from the conductive substrate of the cathode, contact with the ion conductive electrolyte The redox capacity generated by the conductive polymer layer of the above cathode can be expressed. The conductive polymer layer is formed of a copolymer of EDOT and a compound represented by formula (I). Therefore, the cathode shows a significantly increased capacity, and even the capacity per unit volume of the electrolytic capacitor increases significantly. During the development of the redox capacity, the ions in the ion conductive electrolyte are incorporated into the conductive polymer layer of the cathode. In addition, since the cathode has a conductive molecular layer formed of a copolymer of EDOT and a compound represented by formula (I), the capacity at the load bias voltage after the high-temperature load test can be improved compared to that at the load bias voltage before the test The situation of capacity decline. [Example]

The following examples are used to illustrate the present invention, but the present invention is not limited to the following examples.

>Example 1> The aluminum foil after the etching process was performed only on the surface layer was perforated so that the projected area was 2.1 cm ² , and a carbon vapor-deposited film was formed on the surface of the natural alumina film to obtain a conductive substrate. According to the above method, this is fixed to the copper foil surface of the carbon film vapor via a carbon paste and silver paste, and for the implementation of the AC impedance measurement between the copper foil and the aluminum foil, the results of resistance of the conductive substrate is 5.3 × 10 ^{- 3} Ωcm ² value.

50 mL of distilled water was introduced into a glass container and heated to 40°C. EDOT and EtEDOT have a molar ratio of 19:1 and a total concentration of 0.03M to introduce EDOT and the compound of formula (I) where R represents ethyl (Et) and x represents 1 (EtEDOT) into this solution In addition, 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalene sulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization using sodium butylnaphthalene sulfonate To make EDOT and EtEDOT soluble in water. Then, the above-described conductive substrate (working electrode) and stainless steel having an area of 10cm ² of (SUS) opposing electrode sites introduced into the electrolytic polymerization polymerization solution, and the implementation of constant current electrolytic polymerization 2 at 500μA / cm ² of minute. After washing the polymerized working electrode with water, it was dried at 100°C for 30 minutes to obtain a cathode in which a P(EDOT-EtEDOT) layer as a conductive polymer layer with a thickness of 350 nm was formed on a carbon vapor-deposited film . In addition, the thickness of the conductive polymer layer is a value obtained by changing the time to perform a plurality of constant current electrolytic polymerizations under the condition of 500 μA/cm ² , and then using an atomic force microscope or surface Use a profilometer to measure the thickness of the conductive polymer layer obtained in each experiment, and derive the relationship between the thickness of the conductive polymer layer and the amount of charge, and then use the derived relationship to convert the amount of charge in the electrolytic polymerization The thickness of the conductive polymer layer.

According to the method described with reference to FIG. 9, the copper foil is fixed to the surface of the P (EDOT-EtEDOT) layer of the cathode via carbon paste and silver paste, and the AC impedance measurement is performed between the copper foil and the aluminum foil, results with P (EDOT-EtEDOT) layer in contact resistance of the conductive substrate was 7.3 × 10 ^{- 3} Ωcm ^2.

The following test was carried out to obtain the reduction peak potential, oxidation peak potential, and the difference between the oxidation peak potential and the reduction peak potential in the cyclic voltammogram of the 5th cycle: using the obtained cathode as the relative An activated carbon electrode having an area of 12 cm ² and a silver-silver chloride electrode as a reference electrode were introduced by dissolving the amidinium phthalate salt in γ-butyrolactone at a concentration of 20% by mass In the electrolytic solution, the cyclic voltammetry of the cathode was measured 5 times at room temperature in the range of -1.2V to +0.2V relative to the silver-silver chloride electrode at a scanning speed of 100mV/s. Furthermore, the obtained cathode, an activated carbon electrode having an area of 12 cm ² as a counter electrode, and a silver-silver chloride electrode as a reference electrode were introduced and measured at room temperature at -0.4 relative to the silver-silver chloride electrode The first cathode capacity at 120 Hz at the potential of V, and then polarized in the cathode direction from -0.4V to -1.0V, reversed the direction of polarization and polarized in the anode direction until- After 0.6V, the second cathode capacity at 120 Hz at a potential of -0.6V was measured, and then the ratio of the second cathode capacity to the first cathode capacity was calculated.

Using the above-mentioned aluminum foil punched with a projection area of 2.1 cm ^2, a conductive substrate having a carbon vapor-deposited film formed on the surface of a natural alumina film is obtained, and the obtained conductive substrate and the counter electrode are introduced into the above In the polymerization solution for electrolytic polymerization, a constant current electrolytic polymerization was carried out under the conditions of 500 μA/cm ² for 2 minutes, and the working electrode after polymerization was washed with water, followed by drying at 100° C. for 30 minutes to obtain a cathode. The thickness of the P(EDOT-EtEDOT) layer on the carbon deposition film was 350 nm. Furthermore, after the etching process was performed to increase the surface area of the aluminum foil surface, an aluminum oxide film was formed by chemical conversion treatment, and a hole was drilled so that the projected area was 2.1 cm ² to obtain an anode (capacity: 370 μF/cm ² ). Then, the above-mentioned cathode and the above-mentioned anode were laminated via a cellulose separator to produce a capacitor element, and then the amidinium phthalate was dissolved in γ-butyrolactone at a concentration of 20% by mass The electrolyte is impregnated in this element, and laminated packaging. Then, a voltage of 3.35 V was applied at a temperature of 105° C. for 60 minutes to perform a reforming process to obtain a flat-type electrolytic capacitor.

For this capacitor, a bias voltage of 2.9V was loaded at room temperature, and the capacitance of the capacitor at 120Hz and 10kHz was measured, and a high temperature load test was carried out. The high temperature load test was to apply a DC voltage of 2.4V at 125°C for 1060 hours. After the test, the bias voltage of 2.9 V was loaded again at room temperature, and the capacitor capacity at 120 Hz and 10 kHz was measured.

> Example 2> 50 mL of distilled water was introduced into a glass container and heated to 40°C. EDOT and EtEDOT have a molar ratio of 9:1 and a total concentration of 0.03M to introduce EDOT and the compound of formula (I) where R represents ethyl (Et) and x represents 1 (EtEDOT) into this solution In addition, 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalene sulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization using sodium butylnaphthalene sulfonate To make EDOT and EtEDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the P (EDOT-EtEDOT) layer in contact resistance of the conductive substrate was 5.9 × 10 ^{- 3} Ωcm ^2.

> Example 3> 50 mL of distilled water was introduced into a glass container and heated to 40°C. EDOT and EtEDOT have a molar ratio of 7:1 and a total concentration of 0.03M to introduce EDOT and the compound of formula (I) where R represents ethyl (Et) and x represents 1 (EtEDOT) into this solution In addition, 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalene sulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization using sodium butylnaphthalene sulfonate To make EDOT and EtEDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the P (EDOT-EtEDOT) layer in contact resistance of the conductive substrate was 8.3 × 10 ^{- 3} Ωcm ^2.

> Example 4> 50 mL of distilled water was introduced into a glass container and heated to 40°C. EDOT:EtEDOT has a molar ratio of 3:1 and a total concentration of 0.03M to introduce EDOT and the compound of formula (I) where R represents ethyl (Et) and x represents 1 (EtEDOT) into this solution In addition, 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalene sulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization using sodium butylnaphthalene sulfonate To make EDOT and EtEDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the P (EDOT-EtEDOT) layer in contact resistance of the conductive substrate was 5.4 × 10 ^{- 3} Ωcm ^2.

>Example 5> 50 mL of distilled water was introduced into a glass container, and heated to 40°C. EDOT:EtEDOT has a molar ratio of 1:1 and a total concentration of 0.03M to introduce EDOT and the compound of formula (I) where R represents ethyl (Et) and x represents 1 (EtEDOT) into this solution In addition, 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalene sulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization using sodium butylnaphthalene sulfonate To make EDOT and EtEDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the P (EDOT-EtEDOT) layer in contact resistance of the conductive substrate was 1.0 × 10 ^{- 2} Ωcm ^2.

> Example 6> 50 mL of distilled water was introduced into a glass container and heated to 40°C. EDOT:EtEDOT has a molar ratio of 1:3 and a total concentration of 0.03M to introduce EDOT and the compound of formula (I) where R represents ethyl (Et) and x represents 1 (EtEDOT) into this solution In addition, 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalene sulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization using sodium butylnaphthalene sulfonate To make EDOT and EtEDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the P (EDOT-EtEDOT) layer in contact resistance of the conductive substrate was 7.6 × 10 ^{- 3} Ωcm ^2.

>Example 7> 50 mL of distilled water was introduced into a glass container, and heated to 40°C. EDOT: BuEDOT has a molar ratio of 3:1 and a total concentration of 0.03M to introduce EDOT and the compound of formula (I) where R represents butyl (Bu) and x represents 1 (BuEDOT) In addition, 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalene sulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization using sodium butylnaphthalene sulfonate To make EDOT and BuEDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the P (EDOT-BuEDOT) layer in contact resistance of the conductive substrate was 2.2 × 10 ^{- 2} Ωcm ^2.

>Comparative Example 1> 50 mL of distilled water was introduced into a glass container and heated to 40°C. EDOT was introduced into this solution at a concentration of 0.03M, and 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalenesulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization. The polymerization liquid for polymerization uses butyl naphthalene sulfonate to make EDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the contact resistance of the conductive substrate and the PEDOT layer was 1.6 × 10 ^{- 3} Ωcm ^2.

>Comparative Example 2> 50 mL of distilled water was introduced into a glass container and heated to 40°C. EtEDOT was introduced into this solution at a concentration of 0.03M, and 0.04M ammonium borodisalicylate and 0.04M sodium butylnaphthalenesulfonate were further added and stirred to obtain a polymerization solution for electrolytic polymerization. The polymerization solution for polymerization is to use sodium butylnaphthalene sulfonate to make EtEDOT soluble in water. The same procedure as in Example 1 was repeated except that this polymerization liquid was used instead of the electrolytic solution for electrolytic polymerization used in Example 1. Further, the contact resistance of the conductive substrate layer and PEtEDOT 1.0 × 10 ^{- 2} Ωcm ^2.

Table 1 shows the capacitor capacity (Cap) at the load bias voltage at 120 Hz and 10 kHz measured before the high-temperature load test for the electrolytic capacitors obtained in Examples 1 to 7 and Comparative Examples 1 and 2, and the high-temperature load The rate of change of the capacitor capacity at 120 Hz and 10 kHz load bias voltage measured after the test, and the capacitor capacity at 120 Hz and 10 kHz load bias voltage before and after the high temperature load test. [Table 1]

Although the capacitors of Comparative Example 1 and Comparative Example 2 also showed stable capacity after the high-temperature load test, the capacitor of Comparative Example 1 confirmed a significant decrease in capacity after the high-temperature load test, especially at 10 kHz, while the capacitor of Comparative Example 2 After the high temperature load test, both 120Hz and 10kHz confirmed a significant drop in capacity. On the other hand, as can be seen from Table 1, the electrolytic capacitors of Examples 1 to 7 also showed stable capacity after the high-temperature load test, and compared with the case where the capacity of the capacitor of Comparative Example 1 decreased, the high-temperature load test was significantly improved The capacity after the test is lower than the capacity before the test. Therefore, it is known that an electrolytic capacitor includes a cathode having a conductive polymer layer capable of expressing a redox capacity, and is formed by using a copolymer of EDOT and a compound represented by the above formula (I) in the electrolytic capacitor The conductive polymer layer can significantly improve the situation where the capacity at the load bias voltage after the high temperature load test is lower than the capacity at the load bias voltage before the test.

Table 2 shows the potential (Ered) of the reduction peak obtained by the cyclic voltammetry of the fifth cycle for the cathodes of Examples 1 to 7 and Comparative Examples 1 and 2 which also showed stable capacity after the high-temperature load test. The oxidation peak potential (Eox), and the difference between the oxidation peak potential and the reduction peak potential (ΔEp), and represents the cathode capacity at 120 Hz at -0.4V from the starting point measured by Cathode capacity, C (-0.4V)), the cathode capacity at the last point -0.6V at 120Hz (second cathode capacity, C (-0.6V)) and the second cathode capacity relative to the first cathode capacity Ratio: Starting from -0.4V with respect to the silver-silver chloride electrode, after polarizing in the cathode direction to -1.0V, reverse the direction of polarization and polarize in the anode direction until -0.6 Measure up to V. [Table 2]

It can be seen from Table 2 that the cathodes of Examples 1 to 7 having a P(EDOT-EtEDOT) layer or a P(EDOT-BuEDOT) layer are on the more negative side than the cathode of Comparative Example 1 having a PEDO layer The oxidation peak and the reduction peak are displayed, and the difference between the potential of the oxidation peak and the reduction peak is enlarged. In addition, compared to the cathode of Comparative Example 1 having a PEDO layer, the cathodes of Examples 1 to 7 having a P (EDOT-EtEDOT) layer or a P (EDOT-BuEDOT) layer at 120 Hz at -0.6V The cathode capacity (second cathode capacity, C(-0.6V)) is particularly increased, and the second cathode capacity is relative to the cathode capacity at 120Hz at -0.4V (first cathode capacity, C(-0.4V)) The ratio is over 80%. It was judged that the capacitors of Examples 1 to 7 reflected these characteristics, showed high capacity before the high temperature load test, and improved the situation where the capacity at the load bias voltage after the high temperature load test was lower than the capacity at the load bias voltage before the test. On the other hand, compared to the cathode of Comparative Example 1 having a PEDO layer, the cathode of Comparative Example 2 having a PEtEDOT layer also shows an oxidation peak and a reduction peak on the more negative side, so it is expected to suppress the load after the high-temperature load test The case of the capacity decrease at the bias voltage, but it can be confirmed from Table 1, that the capacity decrease cannot actually be suppressed, so it is known that the conductive polymer formed by using the copolymer of EDOT and the compound represented by the above formula (I) The layer is very important. [Industry availability]

According to the present invention, it is possible to obtain an electrolytic capacitor that is small and has a large capacity, and that can withstand the use at high temperatures.

no

Fig. 1 is a graph showing the results of cyclic voltammetry performed on a cathode having a PEDOT layer. Fig. 2 is a graph showing a comparison between the results of cyclic voltammetry performed on a cathode with a PEtEDOT layer and the cyclic voltammetry on a cathode with a PEDOT layer. FIG. 3 is a diagram showing a comparison between the results of cyclic voltammetry performed on a cathode having a P(EDOT-EtEDOT) layer and a cyclic voltammetry diagram on a cathode having a PEDOT layer. Fig. 4 is a graph showing a comparison between the results of cyclic voltammetry performed on another form of a cathode having a P(EDOT-EtEDOT) layer and a cyclic voltammetry chart on a cathode having a PEDOT layer. Fig. 5 is a graph showing a comparison between the results of cyclic voltammetry performed on another form of a cathode having a P(EDOT-EtEDOT) layer and a cyclic voltammetry chart on a cathode having a PEDOT layer. Fig. 6 is a graph showing a comparison between the results of cyclic voltammetry performed on another form of a cathode having a P(EDOT-EtEDOT) layer and a cyclic voltammetry chart on a cathode having a PEDOT layer. Fig. 7 is a graph showing a comparison between the results of cyclic voltammetry performed on another form of a cathode having a P(EDOT-EtEDOT) layer and the cyclic voltammetry chart on a cathode having a PEDOT layer. FIG. 8 is a diagram showing a comparison between the results of cyclic voltammetry performed on another form of a cathode having a P(EDOT-EtEDOT) layer and a cyclic voltammetry chart on a cathode having a PEDOT layer. Fig. 9 is a schematic diagram for explaining the measurement method of the contact resistance between the conductive substrate and the conductive polymer layer in the cathode, (a) shows the measurement method when the conductive substrate is composed of one conductive layer , (B) is a diagram showing a measurement method when the conductive substrate is composed of two conductive layers.

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Claims (9)

An electrolytic capacitor comprising: a cathode having a conductive substrate and a conductive polymer layer provided on the surface of the conductive substrate; an anode having a substrate made of valve metal and provided on the surface of the substrate A dielectric layer composed of the oxide of the valve metal, and the dielectric layer and the conductive polymer layer of the cathode are arranged in a manner facing each other across a space; and, an ion conductive electrolyte , Which is filled in the space; and, by applying a voltage between the anode and the cathode, the conductive polymer layer of the cathode in contact with the ion conductive electrolyte exhibits a redox capacity; It is characterized in that the conductive polymer layer in the cathode is composed of a copolymer of 3,4-ethylenedioxythiophene and at least one compound selected from the group consisting of compounds represented by formula (I) constitute,

In formula (I), R represents a linear or branched alkyl group having 1 to 10 carbon atoms, x represents an integer of 1 to 4, and when x represents an integer of 2 or more, each R may be the same or different. The electrolytic capacitor according to claim 1, wherein x in the aforementioned formula (I) represents 1, and R represents a linear alkyl group having 1 to 10 carbon atoms The electrolytic capacitor according to claim 1 or 2, which includes a cathode whose second cathode capacity in the following test is 80% or more of the first cathode capacity: the cathode is introduced at a concentration of 20% by mass The amidinium salt of phthalic acid is dissolved in an electrolyte obtained from γ-butyrolactone, and the first cathode capacity at 120 Hz at a potential of −0.4 V relative to the silver-silver chloride electrode at room temperature is measured at room temperature , And then polarize from -0.4V in the cathode direction to -1.0V, reverse the direction of polarization, and polarize in the anode direction until -0.6V, and then measure the potential at -0.6V The second cathode capacity at 120 Hz. The electrolytic capacitor according to any one of claims 1 to 3, comprising a cathode whose potential of the reduction peak in the cyclic voltammogram of the 5th cycle in the following test is lower than -0.55V Potential: The cathode was introduced into an electrolyte obtained by dissolving the amidinium salt of phthalic acid at a concentration of 20% by mass in γ-butyrolactone at room temperature relative to the silver-silver chloride electrode- The cyclic voltammetry of the cathode was measured for 5 cycles at a scanning speed of 100 mV/s in the range of 1.2V to +0.2V. The electrolytic capacitor according to any one of claims 1 to 4, comprising a cathode whose difference between the potential of the oxidation peak and the potential of the reduction peak in the cyclic voltammogram of the 5th cycle in the following test The value is in the range of 0.20 to 0.80V: the foregoing cathode is introduced into an electrolytic solution obtained by dissolving the amidinium phthalate salt in γ-butyrolactone at a concentration of 20% by mass at room temperature relative to Silver-silver chloride electrode-Cyclic voltammetry of the cathode was measured 5 times at a scanning speed of 100 mV/s within a range of -1.2V to +0.2V. The electrolytic capacitor according to any one of claims 1 to 5, wherein the contact resistance between the conductive substrate and the conductive polymer layer in the cathode is 1 Ωcm ² or less. The electrolytic capacitor according to claim 6, wherein the conductive substrate includes an aluminum foil and an inorganic conductive layer, the aluminum foil includes an aluminum oxide film, the inorganic conductive layer is provided on the surface of the aluminum oxide film, and includes an inorganic conductive material, The inorganic conductive layer communicates with the aluminum foil, and the conductive polymer layer is provided on the surface of the inorganic conductive layer. A method of manufacturing an electrolytic capacitor comprising: a cathode having a conductive substrate and a conductive polymer layer provided on the surface of the conductive substrate; an anode having a substrate made of valve metal and provided on A dielectric layer composed of the oxide of the valve metal on the surface of the substrate, and the dielectric layer and the conductive polymer layer of the cathode are arranged to face each other across a space; and , An ion conductive electrolyte filled in the space; and by applying a voltage between the anode and the cathode, the conductive polymer layer of the cathode in contact with the ion conductive electrolyte exhibits a redox capacity ; The manufacturing method of the electrolytic capacitor is characterized by comprising the following steps: a cathode forming step which forms a conductive polymer layer on the surface of a conductive substrate to obtain a cathode for the electrolytic capacitor, the conductive polymer The layer is composed of a copolymer of 3,4-ethylidene dioxythiophene and at least one compound selected from the group consisting of compounds represented by the aforementioned formula (I),

In formula (I), R represents a linear or branched alkyl group having 1 to 10 carbon atoms, x represents an integer of 1 to 4, and when x represents an integer of 2 or more, each R may be the same or Different; the anode forming step, which oxidizes the surface of the substrate composed of the valve metal to form a dielectric layer composed of the aforementioned valve metal oxide to obtain an anode for the aforementioned electrolytic capacitor; the electrolyte filling step, It opposes the conductive polymer layer of the cathode and the dielectric layer of the anode in a spaced manner, and fills the space with an ion conductive electrolyte; and, a redox capacity induction step, which is A voltage is applied between the cathode and the anode, and electrons are supplied to the conductive polymer layer from the conductive substrate of the cathode, so that the conductive polymer layer of the cathode in contact with the ion conductive electrolyte exhibits a redox capacity. The method for manufacturing an electrolytic capacitor according to claim 8, wherein, in the cathode forming step, the conductive polymer layer is formed by electrolytic polymerization using a polymerization solution containing a molar ratio of 19:1 ~1:7 3,4-ethylidene dioxythiophene and at least one compound selected from the group consisting of the compounds represented by the aforementioned formula (I).

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