Capacitor

Abstract

This provides a capacitor with excellent cycle durability under high voltage conditions. [Solution] The electrolyte of the capacitor contains a compound represented by formula 1, a solvent, and a salt. TIFF2026136743000010.tif2384 R 1 , R 2 is a substituent, L is a single bond or a divalent linking group, and X is a group selected from the group of formulas A to C. JPEG2026136743000011.jpg50101

Description

[Technical Field]

[0001] This invention relates to a capacitor. [Background technology]

[0002] In recent years, various types of capacitors have been developed in connection with power supplies for small portable devices such as mobile phones, off-peak electricity storage systems, distributed home energy storage systems based on solar power generation, and energy storage systems for electric vehicles. For example, the capacitor described in Patent Document 1 can be cited. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2017 / 047550 [Overview of the project] [Problems that the invention aims to solve]

[0004] Recently, the use of capacitors under high voltage conditions has been considered, and there has been a need for further improvements in cycle durability under high voltage conditions.

[0005] In view of the above circumstances, the present invention aims to provide a capacitor that exhibits excellent cycle durability under high voltage. Excellent cycle durability under high voltage means that the capacitance after 1000 charge-discharge cycles under high voltage does not decrease significantly from the initial capacitance. [Means for solving the problem]

[0006] As a result of diligent study on the above-mentioned problems, the inventors of this invention have found that the above-mentioned problems can be solved by the means described below, and have completed the present invention.

[0007] [1] First electrode and Electrolyte and A capacitor comprising a second electrode The capacitor, wherein the electrolytic solution contains a compound represented by the following formula (1), a solvent, and a salt 〔2〕 The capacitor according to 〔1〕, wherein the compound represented by the formula (1) is a compound represented by the following formula (2). 〔3〕 The capacitor according to 〔1〕 or 〔2〕, wherein X represents a group represented by the above formula (A). 〔4〕 The capacitor according to any one of 〔1〕 to 〔3〕, wherein L represents a divalent conjugated linking group 〔5〕 The capacitor according to any one of 〔1〕 to 〔4〕, wherein the content of the compound represented by the formula (1) is 0.01 to 10% by mass based on the total mass of the electrolytic solution 〔6〕 The capacitor according to any one of 〔1〕 to 〔5〕, wherein the solvent is selected from the group consisting of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, and aprotic solvents

Advantages of the Invention

[0008] According to the present invention, a capacitor excellent in cycle durability under high voltage can be provided

Brief Description of the Drawings

[0009] [Figure 1] It is a diagram showing a schematic configuration of an embodiment of the capacitor of the present invention

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail In this specification, "~" is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value In this specification, unless otherwise specified, each component may be used alone as one kind of the substance corresponding to each component, or two or more kinds may be used in combination. In this specification, when there are two or more kinds of a certain component, unless otherwise specified, the "content" of that component means the total content of those two or more kinds of components

[0011] [Capacitor] The capacitor of the present invention is a capacitor including a first electrode, an electrolytic solution, and a second electrode, wherein the electrolytic solution contains a compound represented by the following formula (1) (hereinafter, also simply referred to as "compound (1)"), a solvent, and a salt.

[0012] As a characteristic point of the capacitor of the present invention, for example, the use of compound (1) can be mentioned. For example, under a high voltage of 4V or more, the electrical characteristics may deteriorate due to decomposition of members in the capacitor during charge and discharge cycles. X in formula (1) is a group capable of electrolytic polymerization. Therefore, when the capacitor using the electrolytic solution containing compound (1) is charged and discharged, the polymerization of compound (1) proceeds through the X portion, and a film can be formed on the first electrode or the second electrode. It is presumed that the formation of this film suppresses the oxidative decomposition of the solvent (for example, carbonate-based solvent) in the electrolytic solution. Further, as the effect of compound (1), the improvement of the stability of the first electrode or the second electrode due to the coordination of the nitrogen atom and the aromatic ring structure possessed by compound (1) to the first electrode or the second electrode, and the expression of the function of the nitrogen atom possessed by compound (1) to trap acids derived from salts contained in the electrolytic solution can also be mentioned. As a result of these actions, it is considered that the cycle durability under high voltage is excellent.

[0013] Hereinafter, the excellent cycle durability under high voltage is also referred to as "the effect of the present invention is excellent".

[0014] The capacitor is not particularly limited, and specifically, for example, a supercapacitor can be mentioned. A supercapacitor, for example, forms an electric double layer that arranges ions having opposite charges to the charges at the interface on the electrode solution side of the interface between the electrode and the electrolytic solution, and accumulates a large amount of charges by this electric double layer. A so-called electric double layer capacitor is a kind of supercapacitor. The supercapacitor is a capacitor comprising a first electrode, an electrolyte, and a second electrode, wherein the first electrode comprises a first current collector and a first polarizing electrode layer formed on the first current collector containing a first active material, the electrolyte comprises a compound represented by formula (1), a solvent, and a salt, and the second electrode comprises a second current collector and a second polarizing electrode layer formed on the second current collector containing a second active material. Preferred embodiments of the various components will be described later, but the first active material is preferably a material different from a material that allows for the reversible insertion and removal of lithium ions (preferably activated carbon), and the second active material is preferably a material different from a material that allows for the reversible insertion and removal of lithium ions (preferably activated carbon). The first polarizing electrode layer and the second polarizing electrode layer may be the same or different, and the first active material contained in the first polarizing electrode layer and the first active material contained in the second polarizing electrode layer may be the same or different from each other.

[0015] The first electrode and the second electrode may be the same or different, and it is preferable that the first electrode and the second electrode are the same. It is preferable that one of the first electrode and the second electrode is the negative electrode and the other is the positive electrode.

[0016] <Electrolyte> A capacitor contains an electrolyte.

[0017] (Compound (1)) The electrolyte contains compound (1).

[0018] [ka]

[0019] R 1 and R 2 Each of these independently represents a substituent. The type of the substituent is not particularly limited. For example, it includes a halogen atom, an alkyl group (including a cycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group), an alkynyl group, an aromatic group (e.g., an aromatic hydrocarbon group, an aromatic heterocyclic group), a cyano group, a hydroxy group, a nitro group, a carboxyl group, an alkoxy group, an aryloxy group, a silyloxy group, a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group (including an anilino group), an acylamino group, an aminocarbonylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfamoylamino group, an alkyl and arylsulfonylamino group, a mercapto group, an alkylthio group, an arylthio group, a heterocyclic thio group, a sulfamoyl group, a sulfo group, an alkyl and arylsulfinyl group, an alkyl and arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an aryl and heterocyclic azo group, an imide group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a silyl group, and a group formed by combining these. Further, the above-mentioned substituent may be further substituted with another substituent.

[0020] R 1 and R 2 may be bonded to each other to form a ring. R 1 and R 2 The ring formed by bonding R and R to each other may be an aliphatic ring or an aromatic ring. Further, R 1 and R 2 The ring formed by bonding R and R to each other may be a monocyclic ring or a condensed ring, and a condensed ring is preferable in terms of excellent effects of the present invention. The number of rings contained in the condensed ring is not particularly limited, and 2 to 5 is preferable, 3 to 4 is more preferable, and 3 is still more preferable. R 1 and R 2 The number of carbon atoms contained in the ring formed by bonding R and R to each other is not particularly limited, and 6 to 20 is preferable, 10 to 15 is more preferable. R 1 and R 2 An example of a ring formed by the bonding of these elements together is acenaphthene.

[0021] Each L independently represents a single bond or a divalent linking group. The types of divalent linking groups are not particularly limited and include, for example, -O-, -C(=O)-, -NH-, -C(=O)NH-, -C(=O)O-, alkylene groups, alkenylene groups, alkynylene groups, arylene groups, heteroarylene groups, and groups that are combinations thereof. In particular, a divalent conjugated linking group is preferred as the divalent linking group. When L is a divalent conjugated linking group, the conductivity of the film formed by compound (1) is better, and as a result, the discharge capacity during charging and discharging is better. A divalent conjugated linking group refers to a divalent linking group in which a conjugated system connects from one bond site to the other bond site. Examples of divalent conjugated linking groups include arylene groups, heteroarylene groups, and -CR groups. 3 =CR 3 Examples include -, -C≡C-, -N=N-, -arylene group-Y-, -heteroarylene group-Y-, and groups that combine these. R 3 Each of these independently represents a hydrogen atom or a substituent. The definition of a substituent is as described above in R 1 and R 2 This is synonymous with the substituent represented by . Y represents -O-, -S-, or -NH-.

[0022] The number of carbon atoms in the arylene group is not particularly limited, but 6 to 30 is preferred, 6 to 20 is more preferred, and 6 to 10 is even more preferred in terms of achieving superior effects of the present invention. Examples of rings constituting the arylene group include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a fluorene ring, a triphenylene ring, a pyrene ring, a naphthacene ring, a biphenyl ring (the two phenyl groups may be linked in any configuration), and a terphenyl ring (the three phenyl groups may be linked in any configuration), with the benzene ring being preferred.

[0023] The heteroarylene group may have a monocyclic or fused ring structure. In the case of a fused ring structure, it may be composed of multiple aromatic heterocycles, or it may be composed of a combination of an aromatic hydrocarbon ring and an aromatic heterocycle. Examples of heteroatoms included in a heteroarylene group include oxygen atoms, sulfur atoms, and nitrogen atoms. Examples of aromatic heterocycles included in the heteroarylene group include furan rings, thiophene rings, pyrrole rings, oxazole rings, isoxazole rings, oxadiazole rings, thiazole rings, isothiazole rings, thiadiazole rings, imidazole rings, pyrazole rings, triazole rings, furazan rings, tetrazole rings, pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, triazine rings, tetrazine rings, benzofuran rings, isobenzofuran rings, benzothiophene rings, indole rings, indoline rings, isoindole rings, benzoxazole rings, benzothiazole rings, indazole rings, benzimidazole rings, quinoline rings, isoquinoline rings, sinnoline rings, phthalazine rings, quinazoline rings, quinoxaline rings, dibenzofuran rings, dibenzothiophene rings, carbazole rings, acridine rings, phenanthridine rings, phenanthroline rings, phenazine rings, naphthyridine rings, purine rings, and pteridine rings.

[0024] Each X independently represents a group selected from the group consisting of the group represented by formula (A), the group represented by formula (B), and the group represented by formula (C). Among these, the group represented by formula (A) is preferred because it facilitates the synthesis of compound (1). In formulas (A) to (C), * represents the bond position. More specifically, * represents the bond position with L in formula (1). These groups are electropolymerizable and can polymerize during the charging and discharging of the capacitor.

[0025] [ka]

[0026] The group represented by formula (A) is preferably the group represented by formula (A-1), the group represented by formula (B) is preferably the group represented by formula (B-1), and the group represented by formula (C) is preferably the group represented by formula (C-1). In formulas (A-1), (B-1), and (C-1), * represents the bond position. More specifically, * represents the bond position with L in formula (1). In the case of the group represented by formula (B-1), polymerization proceeds at the 2nd and 5th positions of the thiophene ring, forming polythiophene. In the case of the group represented by formula (C-1), polymerization proceeds at the 2nd and 5th positions of the pyrrole ring, forming polypyrrole.

[0027] [ka]

[0028] In compound (1), if X is a group represented by formula (A), L preferably represents a divalent conjugated linking group, and if X is a group represented by formula (B) or formula (C), L preferably represents a divalent linking group.

[0029] As compound (1), the compound represented by formula (2) is preferred in that it exhibits superior effects compared to the present invention.

[0030] [ka]

[0031] In equation (2), the definitions of L and X are as described above in equation (1).

[0032] The method for synthesizing compound (1) is not particularly limited and can be synthesized by combining known methods.

[0033] The content of compound (1) in the electrolyte is not particularly limited, but in terms of achieving superior effects of the present invention, it is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, and even more preferably 0.10 to 1% by mass, relative to the total mass of the electrolyte.

[0034] (solvent) The electrolyte contains a solvent. The type of solvent is not particularly limited, and examples of non-aqueous solvents include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, and aprotic solvents. Examples of carbonate-based solvents include cyclic carbonate-based solvents and linear carbonate-based solvents, such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, ethylene carbonate, propylene carbonate, and butylene carbonate. Examples of ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, 1,1-dimethylethyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, and caprolactone. Examples of ether-based solvents include dibutyl ether, tetraglycerides, triglycerides, diglymes, dimethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. Examples of ketone solvents include cyclohexanone. Examples of alcohol-based solvents include ethyl alcohol and isopropyl alcohol. Examples of aprotic solvents include nitriles, amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes.

[0035] The solvent content in the electrolyte is not particularly limited, but in terms of achieving superior effects of the present invention, 50 to 99% by mass and 85 to 98% by mass are preferred based on the total mass of the electrolyte.

[0036] (salt) The electrolyte contains salt. Examples of salts include inorganic salts such as lithium salts, sodium salts, and potassium salts, as well as organic salts such as ammonium salts, imidazolium salts, pyrrolidinium salts, pyridinium salts, piperidinium salts, and phosphonium salts. The salt may also be an ionic liquid. The type of lithium salt is not particularly limited; for example, LiPF6, LiBF4, LiClO4, LiAsF6, LiC(CF3SO2)3, Li2SiF6, LiiOSO2C k F 2k+1 [k is an integer from 1 to 8], LiN(SO2C k F 2k+1 )2 [k is an integer from 1 to 8], LiPF n (C k F2 k+1 ) 6-n Examples include [n is an integer from 1 to 5, k is an integer from 1 to 8], LiPF4(C2O2), and LiPF2(C2O2)2. Examples of organic salts include Et4NBF4, Et3MeNBF4, Et1Me3NBF4, Me4NBF4, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-methyl-1-propylpiperidinium bis(trifluoromethylsulfonyl)imide.

[0037] The salt content in the electrolyte is not particularly limited, but 0.2 to 3.0 mol / L is preferred, and 0.4 to 2.0 mol / L is more preferred, in terms of achieving superior effects of the present invention. If the electrolyte contains a lithium salt, the lithium salt content is preferably 0.05 to 3.0 mol / L, more preferably 0.1 to 1.5 mol / L, and even more preferably 0.1 to 0.8 mol / L.

[0038] The electrolyte may contain other components besides the compound (1) described above, the solvent, and the salt.

[0039] The method for preparing the electrolyte is not particularly limited; any method that allows for the uniform dissolution or dispersion of each component by mixing the above-mentioned compound (1), solvent, and salt, as well as any optional components to be added as needed.

[0040] <1st electrode> The capacitor includes a first electrode. The first electrode preferably includes a first current collector and a first polarity-dividing electrode layer formed on the first current collector.

[0041] (First current collector) The type of the first current collector is not particularly limited and includes, for example, an aluminum substrate, copper foil, nickel foil, stainless steel foil, zinc foil, silver foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, a carbon substrate such as carbon film, an oxide substrate such as indium tin oxide, indium zinc oxide and antimony tin oxide, and combinations thereof.

[0042] (First polarity-dividing electrode layer) The first polarity electrode layer preferably contains a first active material and a binder. The first polarizing electrode layer may further contain a conductive additive.

[0043] The first active material described above is preferably a material different from a material that allows for the reversible insertion and removal of lithium ions. Examples of the first active material include porous carbon materials. Examples of porous carbon materials include activated carbon, Ketjenblack, carbon fibers, mesocarbon microbeads, microcapsule carbon, fullerenes, carbon nanofoams, single-walled and multi-walled carbon nanotubes, and carbon nanohorns, with activated carbon being preferred. Furthermore, it is preferable that the first active material does not contain lithium.

[0044] Examples of substances capable of reversible insertion and desorption of lithium ions include alloys of metallic lithium, substances capable of doping and undoping with lithium, and carbon materials capable of reversible insertion and desorption of lithium ions. Examples of alloys of metallic lithium include alloys of lithium with metals such as Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, or Sn. Examples of substances capable of doping and undoping with lithium include Si, SiO x (0 < x < 2), Si-C composites, Si-Q alloys (Q is an alkali metal, alkaline earth metal, group 13-16 element, transition metal, rare earth element, or a combination thereof and is not Si), Sn, SnO2, Sn-C composites, Sn-R (R is an alkali metal, alkaline earth metal, group 13-16 element, transition metal, rare earth element, or a combination thereof and is not Sn). Examples of substances capable of reversible insertion and desorption of lithium ions include carbon materials such as crystalline carbon, amorphous carbon, and substances combining these. Examples of crystalline carbon include graphite, and more specifically, for example, amorphous graphite, plate-like graphite, flaky graphite, spherical graphite, and fibrous graphite. Examples of amorphous carbon include soft carbon, hard carbon, mesophase pitch carbide, and calcined coke.

[0045] The binder serves to make it easier for the first active material to adhere to each other or to make it easier for the first active material to adhere to the first current collector. The type of binder is not particularly limited and includes, for example, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyimide, and polyimideamide.

[0046] There are no particular restrictions on the type of conductive additive; examples include carbon black, acetylene black, copper, nickel, stainless steel, iron, and indium tin oxide.

[0047] <Second electrode> The capacitor includes a second electrode. The second electrode preferably includes a second current collector and a second polarizing electrode layer formed on the second current collector. Examples and preferred embodiments of the second current collector are the same as those of the first current collector described above.

[0048] The second polarizing electrode layer preferably contains a second active material and a binder. The second polarizing electrode layer may contain a conductive additive. Examples and preferred embodiments of the second active material are the same as those of the first active material described above, examples and preferred embodiments of the binder and conductive additive in the second polarizable electrode layer are the same as those of the binder and conductive additive in the first electrode described above, respectively, and examples and preferred embodiments of the second polarizable electrode layer are the same as those of the first polarizable electrode layer in the first electrode described above. As mentioned above, the first polarizing electrode layer and the second polarizing electrode layer may be the same or different from each other, and the first active material and the second active material may be the same or different from each other.

[0049] <Separator> The capacitor preferably includes a separator between the first electrode and the second electrode. There are no particular restrictions on the type of separator; for example, any separator commonly used in conventional capacitors can be used. Examples of materials that make up the separator include glass fiber, polyester, Teflon®, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), and polyimide.

[0050] The form of the capacitor of the present invention is not particularly limited, and conventionally known configurations can be used. Examples of capacitor forms include coin-type, laminate-type, cylindrical-type, and rectangular-type capacitors. [Examples]

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0052] [Example 1] <Synthesis of compound (1)> Compound (1), compound 1, was synthesized according to the following scheme. Under reflux conditions, acetonaphthenequinone (1.49 g) was dissolved in toluene (80 mL). To the resulting solution, a solution of 4,4'-oxydianiline (6.30 g) dissolved in toluene (80 mL) was added to obtain a mixture. Sulfuric acid (0.03 mL) was added dropwise to the mixture, and the mixture was refluxed under a nitrogen atmosphere for 5 hours. The mixture was then allowed to return to room temperature, and the precipitate was collected by filtration and dried. The crude product was dissolved in ethyl acetate (200 mL), and hexane (400 mL) was added, and the mixture was stirred for 30 minutes. The resulting mixture was allowed to stand overnight at -15°C. The red precipitate obtained in the mixture was collected by filtration and dried. The recovered material was purified by column chromatography (hexane / ethyl acetate = 1 / 3) to obtain compound 1 (BIANODA).

[0053] [ka]

[0054] <Capacitor Manufacturing> (Manufacturing of the first and second electrodes) A slurry with a solid content of 20% by mass was prepared by mixing activated carbon (YP-50, 80% by mass of total solids), conductive carbon black (Super P, 10% by mass of total solids), and vinylidene fluoride (PVDF, 10% by mass of total solids) with N-methylpyrrolidone (NMP). Note that "total solids" refers to the total mass of all solids in the slurry (all components other than the solvent (NMP)). The obtained slurry was coated onto carbon-coated aluminum foil and dried under reduced pressure at 80°C. After drying, it was cut into 19 mm diameter discs to obtain the first and second electrodes.

[0055] (Manufacturing of electrolyte) A solution containing 0.8 M Et4NBF4 and 0.2 M LiPF6 in a propylene carbonate solution was prepared by adding compound 1 (1 mg / mL) to the solution, which was used as the electrolyte.

[0056] (Capacitor manufacturing) A coin-type capacitor 100 was fabricated with the configuration shown in Figure 1. The capacitor 100 had a structure in which a first electrode 102, a separator 110, and a second electrode 106 were arranged between an aluminum laminate film container 108 and an aluminum laminate film cap 118, both containing electrolyte 104 (200 μL), and were fixed by a spacer 114 and a spring 116. The first electrode 102 and the second electrode 106 were positioned so that the side coated with the aforementioned slurry faced the separator 110. Glass fiber was used as the separator 110. The first electrode 102 and the container 108 were electrically connected, the second electrode 106 and the cap 118 were electrically connected, and the container 108 and the cap 118 were electrically insulated by the gasket 112.

[0057] [Comparative Example 1] A capacitor of Comparative Example 1 was fabricated using the same procedure as in Example 1, except that a solution without compound 1 was used as the electrolyte.

[0058] [Electrical Characteristics Evaluation] Cyclic voltammetry was performed on each capacitor obtained in Example 1 and Comparative Example 1 in the range of 10 mV to 4.2 V. Electrochemical impedance spectroscopy was also performed at a frequency range of 10 MHz to 0.1 Hz with an amplitude of 10 mV. For each capacitor, a galvanostat charge-discharge cycle test was performed at 25°C under a constant current density of 200 mA / g within a voltage range of 10 mV to 4.2 V. The initial discharge capacity per unit mass of activated carbon (Capacitance, F / g) before the cycle test and the discharge capacity per unit mass of activated carbon (F / g) after 1000 cycles were calculated to evaluate the cycle durability under high voltage. Table 1 shows the ratio of the capacitance after 1000 cycles to the initial capacitance.

[0059] [Table 1]

[0060] As shown in Table 1, the capacitor of the present invention, which uses an electrolyte containing a salt and a compound represented by formula (1), was confirmed to have excellent cycle durability under high voltage. [Explanation of Symbols]

[0061] 100 Capacitors 102 1st electrode 104 Electrolyte 106 2nd electrode 108 Container 110 Separator 112 Gasket 114 Spacer 116 Springs 118 Cap

Claims

1. First electrode and, Electrolyte and A capacitor including a second electrode, A capacitor wherein the electrolyte comprises a compound represented by formula (1), a solvent, and a salt. 【Chemistry 1】 In formula (1), R １ and R ２ Each of these independently represents a substituent. １ and R ２ These may be bonded to each other to form a ring. Each L independently represents a single bond or a divalent linking group. Each X independently represents a group selected from the group represented by formula (A), formula (B), and formula (C). 【Chemistry 2】 In equations (A) through (C), * indicates the joining position.

2. The capacitor according to claim 1, wherein the compound represented by formula (1) is the compound represented by formula (2). 【Transformation 3】 In formula (2), L independently represents a single bond or a divalent linking group. X independently represents a group selected from the group represented by formula (A), formula (B), and formula (C).

3. The capacitor according to claim 1 or 2, wherein X represents a group represented by formula (A).

4. The capacitor according to claim 1 or 2, wherein L represents a divalent conjugated linking group.

5. The capacitor according to claim 1 or 2, wherein the content of the compound represented by formula (1) is 0.01 to 10% by mass relative to the total mass of the electrolyte.

6. The capacitor according to claim 1 or 2, wherein the solvent is selected from the group consisting of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, and aprotic solvents.

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