JP6740566B2 - Electric storage device electrode forming composition, electric storage device electrode, and electric storage device - Google Patents

Description

The present invention relates to a composition for forming an electricity storage device electrode, an electricity storage device electrode, and an electricity storage device.

In recent years, small portable electronic devices such as digital cameras and mobile phones have been widely used. These electronic devices are constantly required to have a minimum volume and a light weight, and a battery mounted therein is also required to have a small size, a light weight and a large capacity. In addition to automotive applications, battery applications such as stationary applications are expanding, and the required performance is increasing year by year. Furthermore, in applications where high output is required, capacitors and the like are sometimes used, and performance improvement is also required here.

In order to meet such demand, attention has been paid to the use of organic compounds as electricity storage materials. Organic compounds allow a variety of molecular designs as compared with inorganic compounds. Therefore, when an organic compound is used as an electricity storage material, it is possible to realize an electricity storage device having various characteristics by molecular design.

Also, unlike metal oxides that have been used as electricity storage materials in the past, organic compounds do not use precious metal elements or harmful heavy metal elements, so a stable supply of raw materials can be expected, and safety in terms of disposal and recycling is also high. It can be expected to improve.

As an example of using an organic compound as a power storage material, for example, a conductive polymer such as polyaniline or polythiophene (Patent Document 1), a compound having a stable radical (Patent Document 2), an organic sulfur-based compound containing a sulfide bond (Patent Document 1) 3) etc. are mentioned. Also, many materials are summarized as a review article by Yanling Liang and the like (Non-Patent Document 1).

However, in such an organic compound that serves as an electricity storage material, partial aggregation often occurs in the formed composite material layer. This is because, for example, it is insoluble in the mixture ink used for forming electrodes and the dispersibility is insufficient in the mixture ink. In that case, a uniform coating film cannot be obtained due to aggregates during electrode coating. In addition, a resistance distribution may occur on the electrodes due to the partial aggregation, current may be concentrated when the device is used as an electricity storage device, and partial heat generation and deterioration may be promoted.

In addition, since an organic compound is generally an insulator, for example, when a redox reaction for charge storage is performed in a battery, if agglomeration occurs, electrons cannot be transferred to the inside of the agglomerate and unreacted, so that discharge capacity can be extracted. Sometimes there is not. Alternatively, even when the electrolytic solution does not permeate into the aggregate, the above problem may occur due to insufficient supply of ions involved in the redox reaction.

JP-A-61-2124070 JP-A-2004-207249 JP 2001-273901 A

Adv. Energy Mater. (2012), 2,742-769

An object of the present invention is to provide an electrode forming composition for forming an electricity storage device having excellent electrode coatability and excellent charge/discharge characteristics, which is effective in mitigating aggregation of an organic active material. Is to provide.

The present invention can alleviate the aggregation of the organic active material by using the anionic dispersant.
That is, the present invention is a composition for forming an electricity storage device electrode, containing an organic active material, an anionic dispersant, a binder resin, and a liquid medium , wherein the organic active material is a quinone compound, a carbonyl compound, a thiocarbonyl compound, Stable radical compound, indigo, indigo carmine, triquinoxalinylene, trioxotriangulene, or at least one selected from the group consisting of heterocyclic compounds containing tetrathiafulvalene and these polymer compounds,
When the anionic dispersant is a copolymer composed of a plurality of monomers and an alkali-neutralized product thereof, and the ratio of the monomers is 100% by mass of the total of the monomers,
10 to 70% by weight of an ethylenically unsaturated monomer (a1) having a carboxyl group, a sulfo group or a phosphoric acid group,
0 to 70% by mass of an ethylenically unsaturated monomer (a2) having an aromatic group,
Other monomer (a3) other than (a1) and (a2) is 0 to 90% by mass.
And the binder resin is a ( meth)acrylic aqueous emulsion.

The present invention also relates to the above-mentioned composition for forming an electricity storage device electrode, which further contains a carbon material which is a conductive additive.

The present invention also relates to an electrode for an electricity storage device, which comprises a current collector and a mixture layer formed from any of the compositions for forming an electricity storage device electrode described above.

The present invention also relates to an electricity storage device including a positive electrode, a negative electrode, and an electrolyte, wherein at least one of the positive electrode and the negative electrode is the electrode for the electricity storage device.

By using the anionic dispersant, the dispersibility of the organic active material and its stability were improved, so that the electrode-forming composition of the present invention could be obtained. The composition for forming an electrode of the present invention can form a composite material layer with less aggregation and can provide an electricity storage device having excellent charge/discharge characteristics.

The electrode for a power storage device can be obtained by various methods.
For example, on the surface of a current collector such as a metal foil,
(1) A power storage device electrode forming composition containing an active material and an anionic dispersant and a liquid medium (hereinafter referred to as a mixture ink),
(2) A mixture ink containing an active material, an anionic dispersant, a conductive additive, and a liquid medium,
(3) A mixture ink containing an active material, an anionic dispersant, a binder, and a liquid medium,
(4) A mixture ink containing an active material, an anionic dispersant, a conductive auxiliary agent, a binder, and a liquid medium,
An electrode can be obtained by forming a composite material layer by using it.

Alternatively, an underlayer is formed on the surface of the current collector of the metal foil by using a composition for forming an underlayer containing a conductive additive and a liquid medium, and the mixture ink (1) is formed on the underlayer. ) To (4) and other mixture inks may be used to form a mixture layer to obtain an electrode.

In any case, the dispersion state of the active material influences the performance of the electricity storage device as described in the background art section.
Therefore, the anionic dispersant in the present invention will be described first.
The anionic dispersant is a dispersant containing a skeleton in which a carboxyl group, a sulfo group, a phosphoric acid group, or at least a part thereof is neutralized.

The anionic dispersant has a function of adsorbing to the organic active material and improving dispersibility and stability of the organic active material. Examples of the anionic dispersant include polymer dispersants and surfactants, and compounds generally known as dispersants can be used. The anionic dispersant is preferably a polymer type in consideration of dispersibility of the organic active material and stability thereof.

Examples of the polymeric anionic dispersant include a single polymerizable monomer such as (meth)acrylic acid, itaconic acid, fumaric acid, maleic acid, 3-sulfoethyl acrylate, and 2-(acryloyloxy)ethyl phosphate. Examples include polymers and their neutralized products.

Further, the polymer type anionic dispersant may be a copolymer composed of a plurality of monomers exemplified below and their alkali-neutralized products.

Examples of the monomer having a carboxyl group include maleic acid, fumaric acid, itaconic acid, citraconic acid, or alkyl or alkenyl monoesters thereof, phthalic acid β-(meth)acryloxyethyl monoester, isophthalic acid β-( Examples include (meth)acryloxyethyl monoester, terephthalic acid β-(meth)acryloxyethyl monoester, succinic acid β-(meth)acryloxyethyl monoester, acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid. You can

Examples of the monomer having a sulfo group include vinyl sulfonic acid, (meth)allyl sulfonic acid, styrene sulfonic acid, (meth)acryloyloxyethyl sulfonic acid, isoprene sulfonic acid, 2-(meth)acrylamido-2-methylpropane sulfone. Acid, allyloxybenzene sulfonic acid, etc. are mentioned.

Examples of the monomer having a phosphoric acid group include mono(2-acryloyloxyethyl) acid phosphate, mono(2-methacryloyloxyethyl) acid phosphate, diphenyl(2-acryloyloxyethyl) phosphate, diphenyl(2-methacryloyloxyethyl). ) Phosphate, phenyl(2-acryloyloxyethyl) phosphate, acid phosphooxyethyl methacrylate, methacryloyl oxyethyl acid phosphate monoethanolamine salt, 3-chloro-2-acid phosphooxypropyl methacrylate, acid phosphooxypoly Oxyethylene glycol monomethacrylate, acid phosphooxypolyoxypropylene glycol methacrylate, (meth)acryloyloxyethyl acid phosphate, (meth)acryloyloxypropyl acid phosphate, (meth)acryloyloxy-2-hydroxypropyl acid phosphate, (meth) Examples thereof include acryloyloxy-3-hydroxypropyl acid phosphate, (meth)acryloyloxy-3-chloro-2-hydroxypropyl acid phosphate, allyl alcohol acid phosphate and the like.

Examples of the monomer having an aromatic ring include styrene, α-methylstyrene and benzyl(meth)acrylate.

Specific examples of the chain saturated hydrocarbon group-containing monomer include 1 to 22 carbon atoms such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. Alkyl (meth)acrylate of, and preferably an alkyl group-containing acrylate or a corresponding methacrylate having an alkyl group having 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms. These alkyl groups may be branched, and specific examples thereof include isopropyl(meth)acrylate, isobutyl(meth)acrylate, tertiary butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-butylhexyl(meth). ) Acrylate and the like.
In addition, fatty acid vinyl compounds such as vinyl acetate, vinyl butyrate, vinyl propionate, vinyl hexanoate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl stearate and the like can be mentioned.
Further, α-olefin compounds such as 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and the like can be mentioned.

Examples of the monomer having a cyclic saturated hydrocarbon group include isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate and 1-adamantyl (meth)acrylate. Can be mentioned.

Examples of the monomer having a polyoxyalkylene structure include monoethylene having a hydroxyl group at the terminal and a polyoxyalkylene chain, such as diethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate. Acrylate or monomethacrylate, etc., methoxyethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxy polypropylene glycol (meth)acrylate, etc., having an alkoxy group at the end, polyoxyalkylene There are monoacrylates with chains or the corresponding monomethacrylates. Examples of the alkyl vinyl ether compound include butyl vinyl ether and ethyl vinyl ether.
Further, cyclic compounds such as glycidyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate may be used.

Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol mono (meth)acrylate, 4-hydroxystyrene and vinyl alcohol. , Allyl alcohol and the like.
Examples of the vinyl alcohol derivative monomer include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl versatate. A hydroxyl group can be formed by copolymerizing these vinyl esters and saponifying the resulting copolymer with sodium hydroxide or the like.

Examples of nitrogen-containing monomers include N-vinyl-2-pyrrolidone, (meth)acrylamide, N-vinylacetamide, N-methylol (meth)acrylamide, N-methoxymethyl-(meth)acrylamide, and other monoalkylol ( Examples thereof include (meth)acrylamide, N,N-di(methylol)acrylamide, N-methylol-N-methoxymethyl(meth)acrylamide, and N,N-di(methoxymethyl)acrylamide.

Further, as other monomers, perfluoromethylmethyl(meth)acrylate, perfluoroethylmethyl(meth)acrylate, 2-perfluorobutylethyl(meth)acrylate, 2-perfluorohexylethyl(meth)acrylate, etc. Perfluoroalkylalkyl(meth)acrylates having a perfluoroalkyl group having 1 to 20 carbon atoms;
Perfluoroalkyl ethylene such as perfluorobutyl ethylene, perfluorohexyl ethylene, perfluorooctyl ethylene, perfluorodecyl ethylene, perfluoroalkyl group-containing vinyl monomer such as alkylenes, vinyltrichlorosilane, vinyltris(βmethoxyethoxy)silane, vinyl Examples thereof include silanol group-containing vinyl compounds such as triethoxysilane and γ-(meth)acryloxypropyltrimethoxysilane and derivatives thereof, and a plurality of these compounds can be used.

Examples of the ethynyl compound include acetylene, ethynylbenzene, ethynyltoluene, 1-ethynyl-1-cyclohexanol and the like. These may be used alone or in combination of two or more.

The ratio of the monomers constituting the copolymer, which is the polymeric anionic dispersant used in the present invention, is 100% by mass when the total amount of the monomers is 100% by mass.
10 to 70% by weight of an ethylenically unsaturated monomer (a1) having a carboxyl group, a sulfo group or a phosphoric acid group,
0 to 70% by mass of an ethylenically unsaturated monomer (a2) having an aromatic group,
It is preferable that the amount of the other monomer (a3) other than (a1) and (a2) is 0 to 90% by mass.
More preferably, (a1): 15 to 60% by weight, (a2): 20 to 70% by weight, and (a3): 0 to 50% by weight.

The mass average molecular weight of the polymeric dispersant is preferably 1,000 to 100,000, and more preferably 5,000 to 50,000 from the viewpoint of good dispersibility of the organic active material.

Examples of the anionic surfactant include sodium lauryl sulfate, polyoxyethylene alkyl ether sulfate, sodium stearate, sodium dodecylbenzene sulfonate, sodium lauryl phosphate and the like.

(Active material)
The active material used in the composite ink will be described below. The organic active material used in the present invention is one in which an organic molecule itself causes an oxidation-reduction reaction, or one in which an organic molecule functions as a charge carrier to cause a charge-discharge reaction of a battery.

The organic active material is not particularly limited, but conductive polymers such as polyaniline, polyacetylene, polypyrrole, and polythiophene, 1,4-benzoquinone, 2,5-dimethoxy-1,4-benzoquinone, 9,10-anthraquinone, Phenanthrenequinone, quinone compounds such as 5,7,12,14-pentacentetron and polymer compounds thereof, carbonyl compounds such as naphthalenetetracarboxylic dianhydride, perylenetetracarboxylic dianhydride and dilithium rhodisonate, and polymer compounds thereof , Thiocarbonyl compounds such as rubeanic acid and polymer compounds thereof, stable radical compounds such as 2,2,6,6-tetramethylpiperidine-N-oxyl and polymer compounds thereof, indigo, indigo carmine, triquinoxalinylene, trioxo A heterocyclic compound such as triangulene or tetrathiafulvalene or a polymer compound thereof can also be used.

The organic secondary battery is a secondary battery using an organic active material for a positive electrode or a negative electrode. The structure of the secondary battery will be described later.

The positive electrode active material for the organic secondary battery is selected from the above organic active materials. Further, an inorganic active material may be mixed, or an organic active material and an inorganic active material may be combined and used.

Examples of the inorganic active material include oxides of transition metals such as Fe, Co, Ni, and Mn, composite oxides with lithium, inorganic compounds such as transition metal sulfides, and the like. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , and TiO ₂ , powdered lithium nickelate, lithium cobaltate, lithium manganate, and spinel structure lithium manganate. Examples thereof include a composite oxide powder of lithium and a transition metal, a lithium iron phosphate-based material that is a phosphate compound having an olivine structure, and a transition metal sulfide powder such as TiS ₂ and FeS.

As a negative electrode active material for an organic secondary battery, a material capable of doping or intercalating lithium ions is desirable. For example, metallic Li, alloys thereof such as tin alloy, silicon alloy, lead alloy, Li _X Fe ₂ O ₃ , Li _X Fe ₃ O ₄ , Li _X WO ₂ , lithium titanate, lithium vanadate, and silicon. Amorphous carbonaceous materials such as inorganic oxides of metal oxides such as lithium oxide, organic active materials of conductive polymers such as polyacetylene and poly-p-phenylene, soft carbons and hard carbons, and highly graphitized carbon materials Carbonaceous materials such as artificial graphite or natural graphite, carbonaceous powder such as natural graphite, carbon black, mesophase carbon black, resin-fired carbon material, vapor-grown carbon fiber, carbon fiber and the like. These negative electrode active materials may be used alone or in combination of two or more.
Also, different ones of the organic active materials may be used in combination as the negative electrode active material.

(Conductive agent)
Next, the carbon material which is a conductive additive will be described.
The carbon material which is a conductive aid in the present invention is not particularly limited as long as it is a carbon material having conductivity, but graphite, carbon black, conductive carbon fibers (carbon nanotube, carbon nanofiber, carbon fiber) ), fullerene and the like can be used alone or in combination of two or more. It is preferable to use carbon black in terms of conductivity, availability, and cost.

As carbon black, furnace black produced by continuously thermally decomposing a gas or liquid raw material in a reaction furnace, especially Ketjen black made from ethylene heavy oil, and burning the raw material gas to burn the flame into the channel steel bottom surface. Channel blacks that have been rapidly cooled and deposited, and thermal blacks obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, especially various types such as acetylene black using acetylene gas as a raw material, or 2 More than one type can be used together. Further, commonly used oxidation-treated carbon black, hollow carbon and the like can also be used.

The oxidation treatment of carbon is carried out by subjecting carbon to high temperature in air or secondary treatment with nitric acid, nitrogen dioxide, ozone, etc. This is a treatment for directly introducing (covalently bonding) an oxygen-containing polar functional group onto the surface of carbon, and is generally performed to improve the dispersibility of carbon. However, since the conductivity of carbon generally decreases as the amount of introduced functional groups increases, it is preferable to use carbon that has not been oxidized.

The larger the specific surface area of the carbon black used, the more the contact points between the carbon black particles increase, which is advantageous in reducing the internal resistance of the electrode. Specifically, the specific surface area (BET) obtained from the adsorption amount of nitrogen is 20 m ² /g or more and 1500 m ² /g or less, preferably 50 m ² /g or more and 1500 m ² /g or less, and more preferably 100 m ² /G or more and 1500 m ² /g or less is preferably used.

The particle size of carbon black used is preferably 0.005 to 1 μm in primary particle size, and particularly preferably 0.01 to 0.2 μm. However, the primary particle size mentioned here is an average of the particle sizes measured by an electron microscope or the like.

It is desirable that the dispersed particle diameter of the carbon material, which is a conductive auxiliary agent, in the composite ink is reduced to 0.03 μm or more and 5 μm or less.
The term “dispersed particle size” as used herein means a particle size (D50) at which the volume ratio of particles becomes 50% when the volume ratio of the particles is integrated in the volume particle size distribution, and is generally known. Particle size distribution meter, for example, a dynamic light scattering particle size distribution meter (“Microtrac UPA” manufactured by Nikkiso Co., Ltd.).

Examples of commercially available carbon blacks include Toka Black #4300, #4400, #4500, #5500 (Tokai Carbon Co., Furnace Black), Printex L, etc. (Degussa Co., Furnace Black), Raven 7000, 5750, 5250, 5000 ULTRA III, 5000 ULTRA, etc., Conducttex SC ULTRA, Conducttex 975 ULTRA, etc., PUER BLACK 100, 115, 205, etc. (Colombyan company, furnace black), #2350, #2400B, #2600B, #30050B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3030B, #3050B, #3050B, #3030B, #3030B, #3030B, #3030B, #3030B, #3050B. #3350B, #3400B, #5400B, etc. (Mitsubishi Chemical Co., furnace black), MONARCH1400, 1300, 900, VulcanXC-72R, BlackPearls2000, etc. (Cabot Co., furnace black), Ensaco250G, Ensaco260G, Ensaco350G, Super. TIMCAL), Ketjenblack EC-300J, EC-600JD (manufactured by Akzo), Denka Black, Denka Black HS-100, FX-35 (Denki Kagaku Kogyo Co., Ltd., acetylene black), etc. Examples thereof include natural graphite such as graphite, flake graphite, lump graphite, and earth graphite, but the present invention is not limited thereto and two or more kinds may be used in combination.

As the conductive carbon fiber, one obtained by firing from a petroleum-derived raw material is preferable, but one obtained by firing from a plant-derived raw material can also be used. For example, VGCF manufactured by Showa Denko KK manufactured from a petroleum-derived raw material may be mentioned.

The composite ink may further contain a binder.
The binder in the present invention is used for binding particles such as a conductive auxiliary agent and other active materials, and has a small effect of dispersing those particles in a solvent.

As the binder, for example, acrylic resin, polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicone resin, fluororesin, cellulose resin such as carboxymethyl cellulose, styrene. Examples thereof include synthetic rubbers such as butadiene rubber and fluororubber, conductive resins such as polyaniline and polyacetylene, polyvinylidene fluoride, polyvinyl fluoride, and polymer compounds containing a fluorine atom such as tetrafluoroethylene. Further, a modified product, a mixture, or a copolymer of these resins may be used. These binders may be used alone or in combination of two or more.

When an aqueous liquid medium is used, a binder generally called an aqueous emulsion can also be used. The aqueous emulsion is one in which the binder resin is not dissolved in water and is dispersed in the form of fine particles.

The emulsion to be used is not particularly limited, but (meth)acrylic emulsion, nitrile emulsion, urethane emulsion, diene emulsion (SBR etc.), fluorine emulsion (PVDF, PTFE etc.) and the like can be mentioned. Different from the water-soluble polymer, the emulsion preferably has excellent binding property between particles and flexibility (flexibility of the film).

Examples of the liquid medium used in the present invention include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, and phosphorus. Examples thereof include acid esters, ethers, nitriles and water.
Among these, it is preferable to use a polar solvent having a relative dielectric constant of 15 or more. The relative permittivity is one of the indices showing the strength of the polarity of the solvent, and is described in “Solvent Handbook” edited by Asahara et al. (Kodansha Scientific Co., Ltd., 1990).

Further, a film forming aid, a defoaming agent, a leveling agent, an antiseptic, a pH adjusting agent, a viscosity adjusting agent and the like can be added to the mixture ink as required.

<Compound ink>
As described above, a general mixture ink for a power storage device essentially contains an active material and a solvent, and optionally contains a conductive auxiliary agent and a binder.

The active material is preferably contained as much as possible, and for example, the ratio of the active material in the solid content of the composite ink is preferably 30% by mass or more and 99% by mass or less. When the conductive auxiliary agent is contained, the ratio of the conductive auxiliary agent in the solid content of the mixture ink is preferably 0.1 to 85 mass %. When a binder is included, the proportion of the binder in the mixture ink solid content is preferably 0.1 to 25% by mass.

Although it depends on the coating method, the viscosity of the composite ink is preferably 100 mPa·s or more and 30,000 mPa·s or less in the range of solid content of 5 to 90% by mass.

(Disperser/Mixer)
As a device used for obtaining the composition for forming an electrode of the present invention, a disperser or a mixer that is usually used for pigment dispersion can be used.

For example, mixers such as disperser, homomixer, or planetary mixer; homogenizers such as "Clearmix" manufactured by M Technique Co., Ltd. or "Fillmix" manufactured by PRIMIX; paint conditioner (manufactured by Red Devil Co.), ball mill, sand mill Media type dispersing machine such as (Dimino Mill manufactured by Shinmaru Enterprises Co., Ltd.), attritor, pearl mill (“DCP mill” manufactured by Eirich, etc.), or co-ball mill; wet jet mill (“Genus PY” manufactured by Genus, Sugino) Machineless "Starburst", Nanomizer "Nanomizer", etc.), M Technique "Clear SS-5", or Nara Machinery "MICROS" medialess disperser; or other roll mills, etc. However, the present invention is not limited to these. Further, as the disperser, it is preferable to use a disperser that has been subjected to a metal mixing prevention treatment.

For example, when using a media type disperser, a method in which the agitator and vessel are made of a ceramic or resin disperser, or a metal agitator and a disperser in which the vessel surface is treated with tungsten carbide spraying or resin coating, etc. Is preferably used. Then, as the medium, it is preferable to use glass beads, or ceramic beads such as zirconia beads or alumina beads. Also when using a roll mill, it is preferable to use a ceramic roll. Only one type of dispersion device may be used, or a plurality of types of devices may be used in combination.

<Electrode>
The mixture ink of the composition for forming an electricity storage device electrode of the present invention can be applied on a current collector and dried to form a mixture layer, thereby obtaining an electricity storage device electrode.
Alternatively, a base layer may be formed on the current collector, and a mixture layer may be provided on the base layer to obtain an electrode for a power storage device.

(Current collector)
The material and shape of the current collector used for the electrode are not particularly limited, and those suitable for various power storage devices can be appropriately selected.
For example, examples of the material of the current collector include metals and alloys such as aluminum, copper, nickel, titanium, and stainless. In the case of a lithium ion battery, aluminum is particularly preferable as the positive electrode material, and copper is particularly preferable as the negative electrode material.
As the shape, a flat foil is generally used, but a roughened surface, a perforated foil, or a mesh current collector can also be used.

The method for applying the mixture ink or the composition for forming the underlayer on the current collector is not particularly limited, and a known method can be used.
Specific examples thereof include die coating method, dip coating method, roll coating method, doctor coating method, knife coating method, spray coating method, gravure coating method, screen printing method or electrostatic coating method, and drying. As a method, standing drying, blow dryer, warm air dryer, infrared heater, far infrared heater and the like can be used, but the method is not particularly limited thereto.
Further, after the coating, rolling treatment with a lithographic press or a calendar roll may be performed. The thickness of the electrode mixture layer is generally 1 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less. When the underlayer is provided, the total thickness of the underlayer and the mixture layer is generally 1 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less.

<Power storage device>
(Battery configuration)
An electricity storage device such as a secondary battery or a capacitor can be obtained by using an electrode having a mixture layer made of the composition for forming an electricity storage device electrode of the present invention on at least one of a positive electrode and a negative electrode. The electricity storage device includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode and the negative electrode are arranged so as to face each other via a separator or the like.

Examples of the secondary battery include a lithium-ion secondary battery, a sodium-ion secondary battery, a magnesium-ion secondary battery, a sodium-sulfur secondary battery, and a lithium-air secondary battery. Known electrolytes and separators can be used as appropriate.
Examples of the capacitor include a lithium ion capacitor and the like, and conventionally known electrolytic solutions, separators and the like can be appropriately used.

(Electrolyte)
A case of a lithium ion secondary battery will be described as an example. As the electrolytic solution, a solution containing an electrolyte containing lithium dissolved in a non-aqueous solvent is used.
Examples of the electrolyte include LiBF ₄ , LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , Li(CF ₃ SO ₂ ) ₃ C. , LiI, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN, LiBPh _{4 and the} like, but are not limited thereto.
In addition, when lithium does not participate in charge and discharge, other than the above, as the electrolyte, tetraethylammonium tetrafluoroborate (TEABF ₄ ), triethylmethylammonium tetrafluoroborate (TEMABF ₄ ), triethylmethylammonium bis (trifluoro) is used. Examples thereof include chloromethanesulfonyl)imide (TEMATFSI), tetraethylammonium bis(trifluoromethanesulfonyl)imide (TEATFSI), and spiro-(1,1′)-bipyrrolidinium tetrafluoroborate (SBP-BF ₄ ). Further, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF ₄ ), diethylmethyl(2-methoxyethyl)ammonium tetrafluoroborate (DEME-BF ₄ ), trimethylpropylammonium bis(trifluoromethanesulfonyl) It is also possible to use an ionic liquid such as imide (TMPA-TFSI) and butylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP-TFSI).

The non-aqueous solvent is not particularly limited, for example,
Carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate;
Lactones such as γ-butyrolactone, γ-valerolactone, and γ-octanoic lactone;
Glymes such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, and 1,2-dibutoxyethane;
Esters such as methyl formate, methyl acetate, and methyl propionate;
Sulfoxides such as dimethyl sulfoxide and sulfolane; and
Examples thereof include nitriles such as acetonitrile. Further, these solvents may be used alone, or two or more kinds may be mixed and used.

Further, the electrolyte solution may be a gel-like polymer electrolyte which is held in a polymer matrix. Examples of the polymer matrix include, but are not limited to, an acrylate resin having a polyalkylene oxide segment, a polyphosphazene resin having a polyalkylene oxide segment, and a polysiloxane having a polyalkylene oxide segment.

(separator)
Examples of the separator include polyethylene non-woven fabric, polypropylene non-woven fabric, polyamide non-woven fabric, and those obtained by subjecting them to hydrophilic treatment, but are not particularly limited thereto.

(Battery structure)
Lithium ion secondary battery using the composition of the present invention, a lithium ion capacitor, the structure of the air secondary battery is not particularly limited, is usually composed of a positive electrode and a negative electrode, and a separator provided as necessary, Various shapes such as a paper type, a cylinder type, a button type, and a laminated type can be used according to the purpose of use.

Hereinafter, the present invention will be described in more detail with reference to examples, but the following examples do not limit the scope of rights of the present invention. In addition, "part" in an Example and a comparative example represents a "mass part." Unless otherwise specified, the “dispersant” means an anionic dispersant.

[Synthesis example 1]
200.0 parts of n-butanol was charged into a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, and the atmosphere was replaced with nitrogen gas. 11. The inside of the reaction vessel was heated to 110° C., and 60.0 parts of acrylic acid, 100.0 parts of styrene, 40.0 parts of 4-hydroxybutyl acrylate and V-601 (manufactured by Wako Pure Chemical Industries) as a polymerization initiator 12. 0 part of the mixture was added dropwise over 2 hours to carry out a polymerization reaction. After completion of dropping, the mixture was further reacted at 110° C. for 3 hours, 0.6 part of V-601 (manufactured by Wako Pure Chemical Industries) was added, and the reaction was further continued at 110° C. for 1 hour to obtain a copolymer solution. It was
Further, after cooling to room temperature, 74.2 parts of dimethylaminoethanol was added for neutralization. This is the amount that 100% neutralizes acrylic acid. Further, 400 parts of water was added to make the solution water-soluble, and then heated to 100° C., butanol was azeotropically distilled with water, and butanol was distilled off.
It was diluted with water to obtain an aqueous solution of a dispersant having a nonvolatile content of 20%. The viscosity of the aqueous solution of the dispersant having a nonvolatile content of 20% was 40 mPa·s.

[Synthesis example 2]
200.0 parts of N-methyl-2-pyrrolidone (NMP) was charged into a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, and the atmosphere was replaced with nitrogen gas. A mixture of 60.0 parts of acrylic acid, 80.0 parts of styrene, 60.0 parts of 4-hydroxybutyl acrylate and 12.0 parts of V-601 (manufactured by Wako Pure Chemical Industries) by heating the inside of the reaction vessel to 110°C. Was added dropwise over 2 hours to carry out a polymerization reaction. After completion of the dropping, the mixture was further reacted at 110° C. for 3 hours, 0.6 part of V-601 (manufactured by Wako Pure Chemical Industries) was added as a polymerization initiator, and the reaction was further continued at 110° C. for 1 hour to give a copolymerization weight. A combined solution was obtained.
It was diluted with NMP to obtain an NMP solution of a dispersant having a nonvolatile content of 20%. The viscosity of the dispersant solution having a nonvolatile content of 20% was 40 mPa·s.

[Synthesis Examples 3 to 7]
The anionic dispersants of Synthesis Examples 3 to 7 were obtained by the same composition as shown in Table 1 and in the same manner as in Synthesis Example 1.

AA: acrylic acid 2-SEMA: 2-sulfoethyl methacrylate P-1M: 2-methacryloyloxyethyl acid phosphate (manufactured by Kyoeisha Chemical Co., Ltd.)
St: Styrene BzMA: Benzyl methacrylate 4-HBA: 4-hydroxybutyl acrylate BA: Butyl acrylate PME-100: Methoxy polyethylene glycol monomethacrylate (NOF Corp.)
DMAE: Dimethylaminoethanol

[Synthesis example 8]
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser was charged with 40 parts of ion-exchanged water and 0.2 part of ADEKA REASOAP SR-10 (manufactured by ADEKA) as a surfactant, and methyl was added separately. 48.5 parts of methacrylate, 50 parts of butyl acrylate, 1 part of acrylic acid, 0.5 part of 3-methacryloxypropyltrimethoxysilane, 53 parts of ion-exchanged water and ADEKA REASOAP SR-10 (made by ADEKA) as a surfactant. 1% of the pre-emulsion premixed with 1.8 parts was further added. After the internal temperature was raised to 70° C. and the atmosphere was sufficiently replaced with nitrogen, 10% of 10 parts of a 5% aqueous solution of potassium persulfate was added to initiate polymerization. After maintaining the inside of the reaction system at 70° C. for 5 minutes, the remaining pre-emulsion and the remaining 5% aqueous solution of potassium persulfate were added dropwise over 3 hours while maintaining the internal temperature at 70° C., and stirring was continued for another 2 hours. .. After confirming that the conversion rate exceeded 98% by measuring the solid content, the temperature was cooled to 30°C. The pH was adjusted to 8.5 by adding 25% aqueous ammonia, and the solid content was adjusted to 50% with ion-exchanged water to obtain a binder for an aqueous emulsion.

[Example 1]
21 parts of 9,10-anthraquinone which is an organic active material, 3 parts of an aqueous solution of Synthesis Example 1 which is a dispersant (0.6 part as a solid content) and 66.6 parts of water are put in a mixer and mixed, and further sand milled. And disperse, and 5.4 parts of acetylene black (Denka Black HS-100: manufactured by Denki Kagaku Kogyo Co., Ltd.) as a carbon material which is a conductive additive, a binder (polytetrafluoroethylene 30-J: Mitsui DuPont). 4 parts of a 60% aqueous dispersion manufactured by Fluorochemical Co., Ltd.) were mixed to prepare a mixture ink for secondary battery electrodes. The dispersity as a mixture ink was determined by the following method.

[Example 2]
21 parts of 9,10-anthraquinone which is an organic active material, 3 parts of NMP solution of Synthesis Example 2 which is a dispersant (0.6 part as a solid content), and 40.6 parts of NMP were placed in a kneader and dispersed. Furnace black (Mitsubishi Carbon #3050B: Mitsubishi Chemical Co., Ltd.) 5.4 parts as a carbon material which is a conductive additive, binder (KF polymer #7208: Kureha Battery Materials Japan Co., 8% NMP type) 30 parts of the dispersion) was mixed to prepare a mixture ink for secondary battery electrodes. The dispersity as a mixture ink was determined by the following method.

[Examples 3 to 9 and Comparative Examples 1 and 2]
In the same manner as in Example 1 except that the dispersant, conductive additive, and binder shown in Table 2 were used, the secondary battery electrode mixture inks of Examples 3 to 9 and Comparative Examples 1 and 2 were used. A mixture ink for a secondary battery electrode was obtained, and the degree of dispersion as the mixture ink was obtained by the following method. However, in the present specification, Examples 1, 2, 4, 5, 7, and 9 are reference examples.

(Judgment of dispersion degree of composite ink)
The degree of dispersion of the composite material ink was determined by judgment using a grind gauge (according to JIS K5600-2-5).
The evaluation results are shown in Table 2. The numbers in the table indicate the size of coarse particles, and the smaller the number, the better the dispersibility and the more uniform the mixture ink.

[Example 10]
21 parts of 3,4,9,10-perylenetetracarboxylic dianhydride which is an organic active material, 3 parts of the aqueous solution of Synthesis Example 1 which is a dispersant (0.6 part as solid content), and 66.6 parts of water. In a mixer and mixed, and further placed in a sand mill to disperse, and 5.4 parts of acetylene black (Denka Black HS-100) as a carbon material which is a conductive additive, and a binder (polytetrafluoroethylene 30-J). : Mitsui DuPont Fluorochemical Co., Ltd., 60% aqueous dispersion) was mixed with 4 parts to obtain a secondary battery electrode mixture ink, and the dispersibility as a mixture ink was obtained in the same manner as in Example 1. I asked.

[Example 11]
21 parts of 3,4,9,10-perylenetetracarboxylic dianhydride which is an organic active material, 3 parts of NMP solution of Synthesis Example 2 which is a dispersant (0.6 part as solid content), 40.6 parts of NMP. Was placed in a kneader to disperse, and 5.4 parts of acetylene black (Denka Black HS-100) as a carbon material which is a conductive additive, a binder (KF polymer #7208: manufactured by Kureha Battery Materials Japan Co., Ltd.). , 8% NMP-based dispersion) were mixed to obtain a mixture ink for secondary battery electrodes, and the degree of dispersion as the mixture ink was determined by the same method as in Example 1.

[Examples 12 to 18, Comparative Examples 3 and 4]
In the same manner as in Example 10, except that the dispersant, conductive additive, and binder shown in Table 3 were used, the secondary battery electrode mixture inks of Examples 12 to 18 and Comparative Examples 3 and 4 were used. The mixture ink for the secondary battery electrode was obtained, and the dispersity as the mixture ink was determined by the same method as in Example 1. However, in the present specification, Examples 10, 11, 13, 14, 16, and 18 are reference examples.

<Positive electrode>, <Coin type battery>
The secondary battery electrode mixture inks of Examples 1 to 18 and Comparative Examples 1 to 4 were applied on a 20 μm thick aluminum foil serving as a current collector using a doctor blade, and then dried under reduced pressure to dry the electrodes. The thickness was adjusted to 70 μm.

Next, the obtained positive electrode was punched out to a diameter of 16 mm, a working electrode, a metal lithium foil counter electrode, a separator (porous polyolefin film) inserted between the working electrode and the counter electrode, and an electrolytic solution (ethylene carbonate and diethyl carbonate). A coin-type battery made of a non-aqueous electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent prepared by mixing 1:1 (volume ratio) was prepared. The coin type battery was carried out in a glove box whose atmosphere was replaced with argon gas, and after the coin type battery was manufactured, the battery characteristics of the following charge/discharge characteristics and charge/discharge cycle characteristics were evaluated.

(Charge/discharge characteristics)
The obtained coin-type battery was subjected to charge/discharge measurement using a charge/discharge device (SM-8 manufactured by Hokuto Denko KK).
Constant-current charging was continued at a charging current of 60 mA/g until the end-of-charge voltage of 4.2V. After the voltage of the battery reached 4.2 V, constant current discharge was performed at a discharge current of 60 mA/g until the discharge end voltage of 1.5 V was reached. These charging/discharging cycles were set as one cycle, charging/discharging was repeated for three cycles, and the discharging capacity at the third cycle was defined as the initial discharging capacity.
When the active material used was 9,10-anthraquinone, the percentage (%) of the initial discharge capacity of each battery with respect to the initial discharge capacity of Examples 1 to 9 and Comparative Example 1 was calculated as the charge and discharge characteristics. It was The results are shown in Table 2.

In addition, when the active material used is 3,4,9,10-perylenetetracarboxylic dianhydride, the charging/discharging characteristics of Examples 10 to 18 and Comparative Example 4 are different from the initial discharge capacity of Comparative Example 3. The percentage (%) of the initial discharge capacity of the battery was determined. The results are shown in Table 3.

(Charge/discharge cycle characteristics)
Each of the above charge/discharge cycles was performed 30 times, and the discharge capacity retention rate (percentage of the 30th discharge capacity with respect to the initial discharge capacity) was calculated (the closer to 100%, the better). The results are shown in Tables 2 and 3.
◯: “Maintenance rate is 85% or more. Very good”
B: "Maintenance rate is 75% or more and less than 85%. Good".
Δ: “Maintenance rate is 65% or more and less than 75%. Can be used.”
X: "Maintenance rate is less than 65%. Practically problematic and unusable."

As shown in Tables 2 and 3, when the composite material ink containing the composition for forming an electrode of the present invention was prepared, the dispersibility of the organic active material in the composite material ink was improved and aggregation was eliminated, which was excellent. Electrode coatability is obtained. In addition, it is considered that the electrode for an electricity storage device of the present invention suppresses a decrease in discharge capacity, which is considered to be caused by aggregation of an organic active material, in battery characteristics, for example, and further has improved charge/discharge cycle characteristics.

Claims (4)

A composition for forming an electricity storage device electrode, comprising an organic active material, an anionic dispersant, a binder resin, and a liquid medium , wherein the organic active material is a quinone compound, a carbonyl compound, a thiocarbonyl compound, a stable radical compound, indigo. , Indigo carmine, triquinoxalinylene, trioxotriangulene, or at least one selected from the group consisting of heterocyclic compounds containing tetrathiafulvalene and these polymer compounds,
When the anionic dispersant is a copolymer composed of a plurality of monomers and an alkali-neutralized product thereof, and the ratio of the monomers is 100% by mass of the total of the monomers,
10 to 70% by weight of an ethylenically unsaturated monomer (a1) having a carboxyl group, a sulfo group or a phosphoric acid group,
0 to 70% by mass of an ethylenically unsaturated monomer (a2) having an aromatic group,
Other monomer (a3) other than (a1) and (a2) is 0 to 90% by mass.
And the binder resin is a ( meth)acrylic aqueous emulsion, the composition for forming an electrode of an electricity storage device. Furthermore, the composition for electrical storage device electrode formation of Claim 1 containing the carbon material which is a conductive support agent. An electrode for an electricity storage device, comprising a current collector and a mixture layer formed from the composition for forming an electricity storage device electrode according to claim 1. An electricity storage device comprising a positive electrode, a negative electrode, and an electrolyte, wherein at least one of the positive electrode and the negative electrode is the electrode for an electricity storage device according to claim 3.