JP2018081830A - Electrode active material, electrode for power storage element, and power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode active material high in energy density and capable of achieving excellent cycle characteristics.SOLUTION: An electrode active material comprises: polythiophene derivative particles having repeating units represented by formula (1); and a conductive material contained at least partially within the particles. (In the formula (1), Z represents a 5-9 membered heterocyclic ring containing a chalcogen element as ring members, and, when a plurality of chalcogen elements are contained, the chalcogen elements may be the same or different; Ar represents a substituted/unsubstituted aromatic ring or aromatic heterocyclic ring; n represents an integer of 2 or more, preferably an integer of 10-100; and m represents an integer of 0 or 2 or more, preferably an integer of 0 or 10-100)SELECTED DRAWING: None

Description

  The present invention relates to an electrode active material, an electrode for a storage element, and a storage element.

  Examples of power storage elements include batteries such as primary batteries and secondary batteries, and electric double layer capacitors. Among them, secondary batteries are used in various fields and industries such as notebook computers, mobile phones, smartphones, electric vehicles, etc. With the expansion of applications of secondary batteries, high energy density, high-speed charge / discharge, and There is an increasing demand for improved performance such as cycle characteristics.

  In order to satisfy these requirements, various researches and developments on various materials have been conducted, and one of them is improvement of the electrical conductivity of the electrode active material. Since the electrode active material generally has low electrical conductivity, a conductive agent or the like is used at the time of manufacturing the electrode, and the conductive agent forms a conductive path between the electrode active material particles or covers the surface of the electrode active material. Increases the current collection effect. Thereby, since the electroconductivity in an electrode is raised, the capacity | capacitance of a secondary battery is raised.

  For example, a method has been proposed in which the electrode material is formed of a composite of a polymer radical material and a conductive material, so that the electrical conductivity of the electrode is good and the capacity is reduced even when discharged with a large current. (For example, refer to Patent Document 1). In addition, a method of increasing the energy density by using active material particles in which a conductive layer is formed on the surface of particles of an aromatic polymer such as polyaniline has been proposed (for example, see Patent Document 2).

  However, in order to further improve the characteristics of the secondary battery, it is necessary to further improve the electrode material, further increase the capacity of the secondary battery, and improve the cycle characteristics.

  An object of one embodiment of the present invention is to provide an electrode active material having a large energy density and excellent cycle characteristics.

  The electrode active material in one embodiment of the present invention has the following general formula (1):

(However, in the general formula (1), Z represents an atomic group forming a 5- to 9-membered heterocyclic ring containing a chalcogen element as a ring member. When a plurality of the chalcogen elements are contained, the chalcogen elements are the same or different. Ar represents an optionally substituted aromatic ring or an optionally substituted aromatic heterocyclic ring, n represents an integer of 2 or more, and m represents 0 or 2 A polythiophene derivative particle containing a polythiophene derivative having a repeating unit represented by the following formula: and a conductive material at least partially contained in the polythiophene derivative particle.

  The electrode active material according to one embodiment of the present invention has a large energy density and can obtain excellent cycle characteristics.

FIG. 1 is a schematic cross-sectional view illustrating an example of a power storage device to which an electrode active material according to an embodiment is applied. FIG. 2 is an SEM image of the positive electrode active material (A). FIG. 3 is another SEM image of the positive electrode active material (A). FIG. 4 is an SEM image of particles obtained only by kneading a polythiophene derivative and a carbon nanotube. FIG. 5 is a graph showing the relationship between the charge / discharge cycle and the discharge capacity of the batteries of Example 3 and Comparative Example 1.

  Embodiments according to the present invention will be described below. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. . The following description exemplifies an embodiment of the present invention and does not limit the scope of the claims.

<Electrode active material>
An electrode active material according to an embodiment includes polythiophene derivative particles including a polythiophene derivative having a repeating unit represented by the following general formula (1), and a conductive material at least partially included in the polythiophene derivative particles.

  However, in the general formula (1), Z represents an atomic group forming a 5- to 9-membered heterocyclic ring containing a chalcogen element as a ring member. When a plurality of chalcogen elements are contained, the chalcogen elements may be the same or different. . Ar represents an aromatic ring which may have a substituent or an aromatic heterocycle which may have a substituent. n represents an integer of 2 or more, and m represents 0 or an integer of 2 or more.

  The polythiophene derivative particles and the conductive material constituting the electrode active material according to one embodiment will be described.

(Polythiophene derivative particles)
The polythiophene derivative particle is a particle containing a polythiophene derivative having a repeating unit represented by the general formula (1). The polythiophene derivative having a repeating unit represented by the general formula (1) is a stabilized redox compound, and is an organic compound accompanied by a redox reaction in at least one of a charging reaction and a discharging reaction. The polythiophene derivative having a repeating unit represented by the general formula (1) has a high energy density. Therefore, when the polythiophene derivative having the repeating unit represented by the general formula (1) is included in an electrode for a power storage element such as a secondary battery, the electrode can be prevented from peeling from the current collector. The charge / discharge cycle characteristics can be improved.

  In the general formula (1), Z represents an atomic group forming a 5- to 9-membered heterocyclic ring containing a chalcogen element as a ring member as described above. There is no restriction | limiting in particular as a chalcogen element, Although it can select suitably according to the objective, O, S, Se, or Te is preferable and O, S, or Se is more preferable.

  Ar represents an aromatic ring or an aromatic heterocyclic ring as described above. Examples of the aromatic ring include benzene, biphenyl, naphthalene, anthracene, fluorene, pyrene, and derivatives thereof. Examples of the aromatic heterocycle include pyridine, quinoline, thiophene, furan, oxazole, oxadiazole, carbazole, and derivatives thereof. Among these, thiophene and thiophene derivatives are preferable.

  Examples of the substituent of the aromatic ring or aromatic heterocyclic ring include an alkyl group, an alkoxy group, or a halogen atom. Examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, and a butyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  n represents an integer of 2 or more, and preferably 10 to 100. M represents 0 or an integer of 2 or more, and 0 or 10 to 100 is preferable.

  The polythiophene derivative having a repeating unit represented by the general formula (1) is preferably a polythiophene derivative having a repeating unit represented by the following general formula (2).

  However, in General formula (2), R represents a substituted or unsubstituted alkylene group or a substituted or unsubstituted branched alkylene group. p represents an integer of 1 or more. Q represents a chalcogen element. Ar, n, and m represent the same meaning as in the general formula (1).

  R represents a substituted or unsubstituted alkylene group or a substituted or unsubstituted branched alkylene group. Examples of the group that substitutes for these alkylene groups include alkyl groups, alkoxy groups, aryl groups, aryloxy groups, thioalkyl groups, arylthio groups, alkylamino groups, arylamino groups, and halogen atoms.

  Examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, and a butyl group. Examples of the alkoxy group include those in which an alkyl moiety is the alkyl group. Examples of the aryl group include a phenyl group, a 4-toluyl group, a 4-hydroxyphenyl group, a 1-naphthyl group, and a 2-naphthyl group. Examples of the aryloxy group include those in which the aryl moiety is the aryl group. Examples of the thioalkyl group include a methylthio group, an ethylthio group, or a butylthio group.

  Examples of the arylthio group include a phenylthio group. Examples of the alkylamino group include a diethylamino group, a dimethylamino group, and a hydroxyamino group. Examples of the arylamino group include a diphenylamino group and a phenylnaphthylamino group. Examples of the halogen atom include fluorine, chlorine, bromine and the like.

  P is an integer of 1 or more representing the number of repeating units, and represents a number from 1 to 3.

  Q represents a chalcogen element and has the same meaning as Z in the general formula (1).

  The polythiophene derivative having a repeating unit represented by the general formula (1) is preferably a polythiophene derivative having a repeating unit represented by the following general formula (3).

  In General Formula (3), R represents a substituted or unsubstituted alkylene group or a substituted or unsubstituted branched alkylene group. p represents an integer of 1 or more. Ar, n, and m represent the same meaning as in the general formula (1). R and p represent the same meaning as in the general formula (2).

  The polythiophene derivative having a repeating unit represented by the general formula (1) is preferably a polythiophene derivative having a repeating unit represented by the following general formula (4).

  However, in General formula (4), Q represents a chalcogen element. Ar, n, and m represent the same meaning as in the general formula (1).

  Q represents a chalcogen element and has the same meaning as Z in the general formula (1).

  Specific examples of the compound of the polythiophene derivative having the repeating unit represented by the general formula (1) are shown below, but are not limited thereto. In the formula, n represents an integer of 2 or more, and m represents 0 or an integer of 2 or more.

  Among the polythiophene derivative compounds exemplified in Chemical formulas 6 to 9, compounds (2), (3), (4), (5), (8) from the viewpoint of large discharge capacity and easy synthesis. , (10), (11), (16), (26), (32), (36), and (44) are particularly preferred.

  The polythiophene derivative having a repeating unit represented by the general formula (1) can be obtained by polymerizing a thiophene derivative of the general formula (5) or the general formula (6) obtained by the following reaction.

  However, in General Formula (5), Me represents a methyl group, Z represents an atomic group forming a 5- to 9-membered heterocyclic ring containing a chalcogen element as a ring member, and when the chalcogen element includes a plurality of chalcogen elements, It may be the same or different.

  The thiophene derivative represented by the general formula (5) can be synthesized by the method described in Synthetic Communications 28 (12), 2237-2244 (1998). That is, it can be obtained by a nucleophilic substitution reaction using an acid catalyst between an alkoxy-substituted thiophene such as 3,4-dimethoxythiophene and a chalcogen element source such as dithiols or diols. The reaction temperature is preferably 0 ° C to 150 ° C, more preferably 50 ° C to 130 ° C. As the acid catalyst, for example, an acid (Bronsted acid) such as sulfuric acid, hydrochloric acid, phosphoric acid, methanesulfonic acid, trichloroacetic acid, trifluoroacetic acid, and p-toluenesulfonic acid is used. As the reaction solvent, for example, toluene, xylene, anisole, tetralin, methylcyclohexane, ethylcyclohexane, chlorobenzene, orthodichlorobenzene and the like are used.

  The thiophene derivative represented by the general formula (6) can be synthesized by the method described in Journal of Materials Chemistry 8 (8), 1719-1724 (1998). That is, by cyclizing the dibromo form of thione with sodium sulfide nonahydrate and then oxidizing with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Can be obtained. The reaction temperature during cyclization is preferably 0 ° C to 100 ° C, more preferably 10 ° C to 40 ° C. The reaction temperature during the oxidation is preferably from 0 ° C to 150 ° C, more preferably from 80 ° C to 130 ° C.

  Polymerization of the polythiophene derivative can be performed by oxidative coupling polymerization using an oxidizing agent. Examples of the oxidizing agent include iron (III) chloride and an aromatic sulfonic acid metal salt.

  Examples of the aromatic sulfonic acid metal salt include, for example, ferric o-toluenesulfonate, ferric m-toluenesulfonate, ferric p-toluenesulfonate, cupric o-toluenesulfonate, m-toluene. Cupric sulfonate, cupric p-toluenesulfonate, cobalt o-toluenesulfonate, cobalt m-toluenesulfonate, cobalt p-toluenesulfonate, manganese o-toluenesulfonate, manganese m-toluenesulfonate, Examples thereof include manganese p-toluenesulfonate, ferric o-ethylbenzenesulfonate, ferric m-ethylbenzenesulfonate, ferric p-ethylbenzenesulfonate, ferric naphthalenesulfonate, and derivatives thereof.

  Examples of the solvent used for the polymerization include alcohol solvents, halogenated hydrocarbons, aromatic hydrocarbons, acetonitrile, benzonitrile and the like. Examples of the alcohol solvent include methanol, ethanol, butanol and the like. Examples of the halogenated hydrocarbon include chloroform, dichloromethane, 1,2-dichloroethane and the like. Examples of the aromatic hydrocarbon include toluene, xylene, anisole, chlorobenzene, orthodichlorobenzene, nitrobenzene and the like. These may be used individually by 1 type and may use 2 or more types together.

  Moreover, it is preferable that the average particle diameter of polythiophene derivative particle | grains is 0.1-50 micrometers, and it is more preferable that it is 0.1-10 micrometers. When the average particle size is 0.1 to 10 μm, a contact area with the conductive auxiliary agent is secured, and electrical conductivity is improved. The average particle diameter refers to the volume average diameter based on the effective diameter, and the average particle diameter is measured by, for example, a laser diffraction / scattering method or a dynamic light scattering method.

(Conductive material)
There is no restriction | limiting in particular as an electroconductive material used with the electrode active material by one Embodiment, According to the objective, it can select suitably. Examples of the conductive material include a metal material and a carbon-based material.

Examples of the metal material include copper and aluminum. Examples of the carbon-based material include fullerene, nanocarbons, carbon blacks, graphite, activated carbon, mesoporous carbon, carbon fiber, and carbon fiber. Examples of fullerenes include C ₆₀ and C ₇₀ . Examples of the nanocarbons include single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene. Examples of the carbon blacks include ketjen black and acetylene black. These may be used individually by 1 type and may use 2 or more types together.

  The conductive material is present in a state of being at least partially contained in the polythiophene derivative particles. By including at least a part of the conductive material inside the polythiophene derivative particles, the electrical conductivity of the polythiophene derivative is supplemented by the conductive material. Thereby, the transfer of the electrons accompanying the redox of the polythiophene derivative is smoothly performed through the conductive material. As a result, not only the polythiophene derivative existing in the vicinity of the surface of the polythiophene derivative particle but also the polythiophene derivative present inside the polythiophene derivative particle is effectively utilized, so that the energy density of the electrode active material is increased.

  Moreover, it is preferable that a part of electroconductive material exists in the state protruded outside the polythiophene derivative particle. As long as a part of the conductive material exists outside the polythiophene derivative particles, the manner in which the conductive material protrudes outside the polythiophene derivative particles is not particularly limited. For example, a state (state A) in which the conductive material penetrates through the polythiophene derivative particle while the vicinity of the center of the conductive material exists in the polythiophene derivative particle and the end side of the conductive material protrudes outside the polythiophene derivative particle. preferable. Further, for example, a state in which the conductive material exists in the polythiophene derivative particles from one end side to the vicinity of the center of the conductive material, and the other end side of the conductive material protrudes from the surface of the polythiophene derivative particles ( State B) is preferred. When the conductive material protrudes outside the polythiophene derivative particles in a state such as the state A or the state B, the conductive material exists on the surface of the polythiophene derivative particles in addition to the inside of the polythiophene derivative particles. As a result, the electrical conductivity of the electrode active material is further improved, and the transfer of electrons associated with the redox of the polythiophene derivative is performed more smoothly through the conductive material, thereby further improving the energy density of the electrode active material. Can do.

  When the conductive material is included in the polythiophene derivative particles in the state A or the state B, a part of the conductive material protruding outside may be in contact with other polythiophene derivative particles or other polythiophene derivative. It may be contained inside the particles.

  In addition, when the electrode active material according to one embodiment is used for any of the positive electrode and negative electrode storage element electrodes, as will be described later, at least a part of the conductive material is included in the polythiophene derivative particles in the storage element electrode. It may not exist in the specified state. Even in such a case, it is only necessary that the electrode active material according to the embodiment is at least partially included in the electrode for the storage element.

  Further, when the conductive material protrudes outside the polythiophene derivative particles in the state of states A and B, the shape of the conductive material is not particularly limited. For example, the shape of the conductive material is preferably an elongated shape such as a needle shape, a rod shape, or a cylindrical shape, from the viewpoint of ensuring that the conductive material penetrates the polythiophene derivative particles stably.

  The proportion of the conductive material contained in the polythiophene derivative particles is preferably 5 to 40%, and more preferably 5 to 20%. By setting the proportion of the conductive material within this range, it is possible to balance energy density and electrical conductivity.

<Method for producing electrode active material>
The electrode active material according to one embodiment can be obtained by applying a shearing force between the polythiophene derivative particles and the conductive material using a particle composite device. Examples of the particle composite device include Nobilta (registered trademark) and Mechano-Fusion (registered trademark) manufactured by Hosokawa Micron, Paint Shaker device manufactured by Asada Tekko, and Miracle K.K. C. K (kneading disperser), Dry Star (registered trademark) manufactured by Ashizawa Finetech, Sigma Dry (registered trademark), MIRALO (registered trademark) manufactured by Nara Machinery Co., Ltd., COMPOSI (registered trademark) manufactured by Nippon Coke Etc.

  Thus, the electrode active material according to an embodiment has good electrical conductivity by including a conductive material in the polythiophene derivative particles. Thereby, not only the polythiophene derivative existing near the surface of the polythiophene derivative particle but also the polythiophene derivative present inside the polythiophene derivative particle is effectively utilized. For this reason, the high energy density which the polythiophene derivative particle originally has can be used efficiently. As a result, the electrode active material can have a high energy density. In addition, since the electrode active material according to one embodiment has good electrical conductivity, excellent cycle characteristics can be obtained by using the electrode active material for an electrode of a power storage element.

<Electrode for power storage element>
The electrode active material according to one embodiment can be used as the electrode active material of any of the positive electrode and negative electrode storage element electrodes, but is preferably used as the positive electrode active material of the positive electrode from the viewpoint of having a high energy density.

<Storage element>
The electrode active material according to one embodiment can be used in a power storage device that uses an organic compound that is accompanied by a redox reaction in at least one of a charging reaction and a discharging reaction as an electrode active material. A power storage device using an electrode active material for the positive electrode will be described.

  A power storage device according to one embodiment includes a positive electrode, a negative electrode, an electrolyte, and a separator, and an electrode for a power storage device including an electrode active material as a positive electrode active material is applied as a positive electrode. A power storage element can have a high energy density by using an electrode active material as a positive electrode active material. Further, in the positive electrode, the electrical conductivity of the positive electrode is improved by using the electrode active material as the positive electrode active material. Thereby, since the electrical storage element can exhibit the outstanding cycling characteristics, the lifetime of an electrical storage element can be extended.

  A positive electrode, a negative electrode, an electrolyte, a separator, and the like constituting the electric element will be described.

[Positive electrode]
The positive electrode has a positive electrode layer and a positive electrode current collector.

(Positive electrode layer)
The positive electrode layer contains a positive electrode active material, and preferably contains a binder and a conductive additive, and further contains other components as necessary.

  As the positive electrode active material, the electrode active material according to one embodiment is used. Although an electrode active material can be used for the electrode active material of either the positive electrode or the negative electrode for an electricity storage element, it is preferably used as the positive electrode active material for the positive electrode because it has a high energy density.

  There is no restriction | limiting in particular in the shape of a positive electrode, According to the objective, it can select suitably, For example, flat form etc. are mentioned.

  The positive electrode layer may contain a substance other than the electrode active material, for example, a metal oxide or a redox compound.

Examples of the metal oxide include lithium manganate represented by a formula such as LiMnO ₂ , LiNi _0.5 Mn _1.5 O ₄ , LixMn ₂ O ₄ (0 <x <2) or manganic acid having a spinel structure. Lithium: a layered compound represented by a formula such as LiCoO ₂ , LiNiO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ; a phosphate represented by a formula such as LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ System compounds and the like.

  Examples of the redox compound include organic compounds such as an oxy redox compound, a nitroxyl redox compound, a nitrogen redox compound, a carbon redox compound, and a boron redox compound.

  Examples of the redox compound include compounds represented by the following general formulas (R-1) to (R-12), but are not limited thereto. In addition, n in a formula is an integer showing the number of repeating units.

(Binder)
When the electrode active material according to one embodiment is used as the positive electrode active material, a binder may be used to strengthen the bond between the constituent materials. As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polypropylene, polyethylene, Examples thereof include resin binders such as polyimide or various polyurethanes.

(Conductive aid)
The conductive auxiliary agent is contained to assist the exchange of electrons between the positive electrode current collector and the electrode active material. There is no restriction | limiting in particular as a conductive support agent, According to the objective, it can select suitably. Examples of the conductive material include fullerene, nanocarbons, carbon blacks, graphite, activated carbon, mesoporous carbon, carbon fiber, and carbon fiber.

Examples of fullerenes include C ₆₀ and C ₇₀ . Examples of the nanocarbons include single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene. Examples of the carbon blacks include ketjen black and acetylene black. These may be used individually by 1 type and may use 2 or more types together.

  The content of the conductive auxiliary agent is not particularly limited and may be appropriately selected depending on the purpose. From the viewpoint of improving the capacity of the secondary battery, 50 parts by mass to 400 parts with respect to 100 parts by mass of the binder. Part by mass is preferred.

(Positive electrode current collector)
The positive electrode current collector is a member formed of a conductive agent and capable of collecting electric charges generated from the positive electrode. There is no restriction | limiting in particular as a shape, a magnitude | size, and a structure of a positive electrode electrical power collector, According to the objective, it can select suitably. There is no restriction | limiting in particular as a material of a positive electrode electrical power collector, According to the objective, it can select suitably, For example, metal foil, a metal flat plate, a mesh electrode, or a carbon electrode is mentioned. Examples of the metal used for the metal foil or the metal flat plate include nickel, aluminum, copper, gold, silver, an aluminum alloy, and stainless steel.

[Negative electrode]
The negative electrode has a negative electrode layer containing a negative electrode active material and a negative electrode current collector.

(Negative electrode layer)
The negative electrode layer contains a negative electrode active material, and preferably contains a binder and a conductive additive, and further contains other components as necessary. Examples of the negative electrode active material include graphite, amorphous carbon, lithium metal, lithium alloy, lithium ion occlusion carbon, and conductive polymer. These may be used individually by 1 type and may use 2 or more types together. As the binder and the conductive assistant, the same binder and conductive assistant as those of the positive electrode may be used. The electrode active material according to an embodiment may be used as the negative electrode active material. In this case, examples of the positive electrode active material include LiMnO ₂ , LiNi _0.5 Mn _1.5 O ₄ , and LixMn ₂ O. ₄ (0 <x <2) and other formulas such as lithium manganate or spinel structure having a spinel structure; LiCoO ₂ , LiNiO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ And a phosphate compound represented by a formula such as LiFePO ₄ , LiCoPO ₄ , LiNiPO _4, or the like is used.

(Negative electrode current collector)
Examples of the negative electrode current collector include nickel and copper stainless steel.

[Electrolytes]
The electrolyte serves to transport charge carriers between both electrodes of the negative electrode layer and the positive electrode layer, and generally has an ionic conductivity of 10 ⁻⁵ to 10 ⁻¹ S / cm at room temperature. As the electrolyte, for example, an electrolytic solution in which an electrolyte salt is dissolved in a solvent can be used.

Examples of the electrolyte salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, and Li (CF ₃ SO ₂ ). _{3 C, Li (C 2 F} 5 SO 2) such as ₃ C and the like.

  Examples of the electrolyte salt solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoreoethylene carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, dimethylacetamide, and N-methyl. -2-pyrrolidone and the like. These may be used individually by 1 type and may use 2 or more types together.

  Further, a solid electrolyte can be used as the electrolyte. Examples of the polymer compound used for the solid electrolyte include a vinylidene fluoride polymer; an acrylonitrile polymer; a polyethylene oxide, an ethylene oxide-propylene oxide copolymer, and polymers of these acrylates and methacrylates. Can be mentioned.

  Examples of the vinylidene fluoride polymer include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-monofluoroethylene copolymer, and vinylidene fluoride. Examples thereof include a trifluoroethylene copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, and a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer.

  Examples of the acrylonitrile polymer include acrylonitrile-methyl methacrylate copolymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-ethyl methacrylate copolymer, acrylonitrile-ethyl acrylate copolymer, acrylonitrile-methacrylic acid copolymer, Examples include acrylonitrile-acrylic acid copolymer and acrylonitrile-vinyl acetate copolymer.

  The solid electrolyte may be a gel obtained by adding an electrolytic solution to these polymer compounds, or may be used as it is with only the polymer compound.

[Separator]
The separator is provided between the positive electrode and the negative electrode in order to prevent a short circuit between the positive electrode and the negative electrode. There is no restriction | limiting in particular as a material of a separator, According to the objective, it can select suitably. Examples of the material of the separator include paper, cellophane, polyolefin, polyester, polyamide, glass fiber, polyolefin nonwoven fabric, polyester nonwoven fabric, polyamide nonwoven fabric, and glass fiber nonwoven fabric. Examples of paper include kraft paper, vinylon mixed paper, and synthetic pulp mixed paper.

  There is no restriction | limiting in particular as a shape of a separator, According to the objective, it can select suitably, For example, a sheet form etc. are mentioned. The structure of the separator may be a single layer structure or a laminated structure. There is no restriction | limiting in particular as a magnitude | size of a separator, According to the objective, it can select suitably. It is preferable that the separator includes an electrolyte. In addition, when using solid electrolytes, such as an ion conductive polymer, as an electrolyte, a separator itself can also be abbreviate | omitted.

[Exterior container]
The electricity storage device according to one embodiment may have an exterior container. There is no restriction | limiting in particular as a material of an exterior container, According to the objective, it can select suitably, For example, the metal etc. which plated copper, stainless steel, or iron, such as nickel, are mentioned. There is no restriction | limiting in particular as a shape of an exterior container, According to the objective, it can select suitably, For example, the shape of a shallow dish with a curved base, a bottomed cylindrical shape, a bottomed prismatic shape, etc. are mentioned. The structure of the outer container may be a single layer structure or a laminated structure. Examples of the laminated structure include a three-layer structure of nickel, stainless steel, and copper. There is no restriction | limiting in particular as a magnitude | size of an exterior container, According to the objective, it can select suitably.

<Method for manufacturing power storage element>
The method for producing an electricity storage device according to one embodiment is not particularly limited and can be appropriately selected according to the purpose. The positive electrode, the negative electrode, and the electrolyte, and a separator used as necessary are stacked in an appropriate shape. It is manufactured by doing. Furthermore, it is also possible to use other components such as an outer container as necessary. The method for laminating the positive electrode and the negative electrode is not particularly limited, and can be appropriately selected from conventionally employed methods. The positive electrode and the negative electrode are laminated in multiple layers, on both sides of the positive electrode current collector and the negative electrode current collector. The thing which combined the thing laminated | stacked, the thing wound, etc. are mentioned.

  The shape of the power storage element is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include a coin shape, a cylindrical shape, a square shape, a sheet shape, and a button shape.

<Application example of electrode active material>
An example of the electrical storage element to which the electrode active material by one Embodiment is applied is shown in FIG. For convenience of explanation of the power storage element, the following example is described together with a diagram in which the positive electrode is disposed below. However, the present embodiment is not necessarily used in this arrangement. As shown in FIG. 1, the secondary battery 10 includes a positive electrode 11, a negative electrode 12, and a separator 13.

  The positive electrode 11 includes a positive electrode layer 14 containing a positive electrode active material and a positive electrode current collector 15. The negative electrode 12 includes a negative electrode layer 16 containing a negative electrode active material and a negative electrode current collector 17. The separator 13 is disposed between the positive electrode 11 and the negative electrode 12 and contains an electrolyte.

  In the secondary battery 10, the positive electrode current collector 15, the positive electrode layer 14, the separator 13, the negative electrode layer 16, and the negative electrode current collector 17 are placed in the outer container 18 from the bottom side of the outer container 18. The layers are laminated in this order toward the 19 side. In addition, the lamination | stacking method of the positive electrode layer 14 and the negative electrode layer 16 is not specifically limited. As a laminating method, for example, a multilayer in which the positive electrode layer 14, the separator 13, and the negative electrode layer 16 are laminated can be used. One separator 13 is provided with a positive electrode current collector 15 provided on both sides of the positive electrode current collector 15, and the other separator 13 is provided with a negative electrode current collector 17 provided on both sides with a negative electrode layer 16 provided. A multi-layered product can be used. In addition, what wound the positive electrode layer 14, the separator 13, and the negative electrode layer 16 etc. can be utilized.

<Application>
For example, a lithium ion secondary battery is suitable as the application of the electricity storage device according to the embodiment, but the application of the electricity storage device according to the embodiment is not particularly limited and can be used for various applications. Examples of the use of the electricity storage device according to the embodiment include notebook computers, pen input computers, mobile computers, smartphones, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, and liquid crystal televisions. , Handy cleaners, portable CDs, minidiscs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, motors, lighting equipment, toys, game equipment, clocks, strobes, cameras, electric bicycles, electric tools, etc. Or a backup power source.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these Examples. In addition, a present Example is an example which uses the electrical storage element by one Embodiment as a secondary battery.

<Example 1>
(Adjustment of electrode active material)
The compound (2) exemplified in Chemical Formula 6 was prepared as a polythiophene derivative, and carbon nanotubes were prepared as a conductive material. Compound (2) and carbon nanotubes were mixed at a mass ratio of 5: 2 and filled into a vial containing zirconia beads. This was set in a paint shaker manufactured by Asada Iron Works, and shaken for 4 hours. After the treatment, the electrode active material was recovered to obtain a particulate electrode active material. The obtained particulate electrode active material was defined as a positive electrode active material (A). SEM images of the positive electrode active material (A) are shown in FIGS.

(Create electrode layer)
Mix the positive electrode active material (A), acetylene black as a conductive additive, and poly (vinylidene fluoride) as a binder, add N-methylpyrrolidone to the mixture, and knead until the whole becomes uniform A black paste was obtained. The mixing ratio was positive electrode active material (A): acetylene black: binder = 7: 2: 1 in terms of mass ratio. Subsequently, the obtained paste was uniformly coated on the aluminum foil using a blade coating jig. The obtained coating film was put in a warm air drier previously set at 120 ° C. and dried for 20 minutes to produce an electrode layer.

(Production of battery)
The obtained electrode layer was punched into a circular shape having a diameter of 16 mm to obtain a circular positive electrode. The obtained circular positive electrode was placed in a glove box having a dew point temperature of −75 ° C. or lower. Then, a circular positive electrode, a polypropylene porous film separator having a diameter of 16 mm, and a circular Li metal foil cathode having a diameter of 16 mm were laminated in this order in the stainless steel exterior. An ethylene carbonate / diethyl carbonate mixed solution (volume ratio 1: 2) containing 1.0 mol / L LiPF ₆ electrolyte salt as an electrolyte was added. Finally, a cover as a stainless steel sheath was put on and sealed to prepare a battery.

<Examples 2 to 12: Modification of polythiophene derivative>
(Production of battery)
The compound (2) used as the polythiophene derivative in Example 1 is converted into the compounds (3), (4), (5), (8), (10), (11), (11) 16), (26), (32), (36), or (44). Other than that was carried out similarly to Example 1, and produced the battery. Table 1 shows the compounds of polythiophene derivatives used in Examples 2 to 12, respectively.

<Examples 13 to 16: Change of conductive material>
(Production of battery)
A battery was fabricated in the same manner as in Example 1, except that the conductive material used in Example 1 was changed to any one of acetylene black, graphite, graphene, and ketjen black. The conductive materials used in each example are shown in Table 2.

<Comparative Example 1>
(Production of battery)
In Example 1, the positive electrode active material (A) was not adjusted, and the compound (2) exemplified in Chemical Formula 6 as a polythiophene derivative and the carbon nanotube as a conductive material were used as acetylene black as a conductive auxiliary agent. Were combined and kneaded to obtain a paste. In Comparative Example 1, a battery was produced in the same manner as in Example 1 except that the obtained paste was used for production of the electrode layer. FIG. 4 shows an SEM image of particles obtained only by kneading the polythiophene derivative and the carbon nanotube.

<Comparative Examples 2 to 4: Change of conductive material>
(Production of battery)
A battery was fabricated in the same manner as in Comparative Example 1, except that the carbon nanotubes used as the conductive material in Comparative Example 1 were changed to any one of acetylene black, graphite, or graphene. Table 2 shows the conductive materials used in each comparative example.

<Battery evaluation>
The charge / discharge cycle test of the batteries of Examples 1 to 16 and Comparative Examples 1 to 4 was performed. The batteries of Examples 1 to 16 and Comparative Examples 1 to 4 were charged at 0.5C to a charge end voltage of 4.5V, and then discharged to 0.5V at 0.5C. This charging / discharging was made into 1 cycle, and the charging / discharging cycle at 0.5 C was repeated twice. Thereafter, the battery was charged at 1C to the end-of-charge voltage of 4.5V, and then discharged at 1C to 1.4V. This charging / discharging was made into 1 cycle, and the charging / discharging cycle in 1C was repeated 200 times. Here, C represents a discharge rate, a current value that discharges the entire capacity of the battery in one hour is referred to as a 1C rate, and several times the current value is represented as a C rate. The current density for charging / discharging the entire capacity of the secondary battery in n hours is represented by (1 / n) C. 0.5C and 1C mean current values for charging or discharging the total capacity of the secondary battery over 2 hours or 1 hour, respectively. In addition, the discharge capacity per unit weight of the positive electrode active material was measured using an automatic battery evaluation device (1024B-7V0.1A-4, manufactured by Electrofield Co., Ltd.). Tables 1 and 2 show the discharge capacity of the battery after 200 cycles of charge and discharge. Moreover, the relationship between the charge / discharge cycle and the discharge capacity of the batteries of Example 3 and Comparative Example 1 is shown in FIG.

  As shown in FIG. 2 and FIG. 3, the electrode active material obtained in Example 1 has at least a part of carbon nanotubes embedded in the polythiophene derivative particles of compound (2), and the composite particles of these are Was formed. On the other hand, as shown in FIG. 4, in Comparative Example 1, the polythiophene derivative and the carbon nanotube were dispersed only in the kneaded polythiophene derivative and the carbon nanotube. In Comparative Example 1, it was not possible to confirm that at least a part of the carbon nanotubes was contained in the polythiophene derivative particles.

  From the results in Table 1, the batteries of Examples 1 to 16 had a higher discharge capacity after 200 cycles of charge / discharge at 1C than the batteries of Comparative Examples 1 to 4. Moreover, as shown in FIG. 5, the battery of Example 3 was able to maintain a high discharge capacity even while charging and discharging at 1C were repeated 200 cycles. On the other hand, the discharge capacity of the battery of Comparative Example 1 was greatly reduced by the first charge / discharge. In the batteries of Examples 1 to 16, the specific polythiophene derivative particles contain at least a part of the conductive material. And it is thought that the energy density of the battery was increased and the cycle characteristics were improved by using as the positive electrode active material an electrode active material in which a part of the conductive material protruded from the specific polythiophene derivative particles.

  Further, when graphite was used as the conductive material, the discharge capacity after 200 cycles of charge / discharge was larger than other conductive materials (see Examples 13 to 16).

  Therefore, if the electrode active material according to one embodiment is used for a secondary battery, the secondary battery has a high discharge capacity and can be repeatedly charged and discharged for 200 cycles or more, and thus can be effectively used as a secondary battery. It can be said.

DESCRIPTION OF SYMBOLS 10 Secondary battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Positive electrode layer 16 Negative electrode layer

JP 2009-230951 A

JP 2014-99296 A

Claims (8)

The following general formula (1):
(However, in the general formula (1), Z represents an atomic group forming a 5- to 9-membered heterocyclic ring containing a chalcogen element as a ring member. When a plurality of the chalcogen elements are contained, the chalcogen elements are the same or different Ar represents an optionally substituted aromatic ring or an optionally substituted aromatic heterocyclic ring, n represents an integer of 2 or more, and m represents 0 or 2 A polythiophene derivative particle containing a polythiophene derivative having a repeating unit represented by:
A conductive material at least partially contained in the polythiophene derivative particles;
An electrode active material characterized by comprising:   The electrode active material according to claim 1, wherein a part of the conductive material protrudes outside the polythiophene derivative particles.   The electrode active material according to claim 1, wherein the conductive material has a rod shape and penetrates the polythiophene derivative particles.   The electrode active material according to any one of claims 1 to 3, wherein an average particle size of the polythiophene derivative particles is 0.1 to 50 µm.   The electrode active material according to any one of claims 1 to 4, wherein a ratio of the conductive material contained in the polythiophene derivative particles is 5 to 40%.   The electrode active material according to any one of claims 1 to 5, wherein the conductive material is a carbon-based material.   The electrode for electrical storage elements characterized by including the electrode active material as described in any one of Claim 1 to 6. A positive electrode, a negative electrode, and an electrolyte;
Either the said positive electrode or the said negative electrode is the electrode for electrical storage elements of Claim 7, The electrical storage element characterized by the above-mentioned.