JP2014199804A - Conductive composition, collector with ground layer for power storage device, electrode for power storage device, and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive composition having excellent conductivity and adhesion, for forming a power storage device having excellent dispersibility of conductive carbon material or adhesion of an electrode, and excellent charge and discharge cycle characteristics.SOLUTION: A conductive composition contains conductive carbon material (A), a water soluble resin binder (B), a water dispersible resin fine particle binder (C), and an aqueous liquid medium (D). In the total 100 wt% of solid content of the conductive carbon material (A), water soluble resin binder (B), and water dispersible resin fine particle binder (C), content of the conductive carbon material (A) is 20-70 wt%, and in the total 100 wt% of solid content of the water soluble resin binder (B), and water dispersible resin fine particle binder (C), content of the water soluble resin binder (B) is 40-95 wt%.

Description

  The present invention relates to a conductive composition, a current collector with an underlayer for an electricity storage device having an underlayer obtained using the composition, an electrode for an electricity storage device, and an electricity storage device obtained using the electrode.

  In recent years, small portable electronic devices such as digital cameras and mobile phones have been widely used. These electronic devices have always been required to minimize the volume and reduce the weight, and the batteries to be mounted are also required to be small, light, and have a large capacity. Also, in large-sized secondary batteries for automobiles and the like, it is desired to realize a large-sized secondary battery instead of the conventional lead-acid battery, and there is a need for a longer life in various environments where the battery is used. It has been. In addition, capacitors such as electric double layer capacitors and lithium ion capacitors are also attracting attention as power storage devices with high output and high energy density.

  To meet such demands, development of power storage devices such as secondary batteries such as lithium ion secondary batteries and alkaline secondary batteries and capacitors, for example, mixed inks used in the formation of electrodes for these power storage devices, There is also an interest in developing a composition for forming a base layer used for forming a base layer of a composite material layer.

  The important properties required for the composite ink used for forming the electrode and the composition for forming the underlayer include the uniformity in which the active material and the conductive carbon material are appropriately dispersed, and the composite ink and the undercoat layer. The adhesiveness of the electrode formed after drying of the composition for formation is mentioned.

  The distribution of the active material and conductive carbon material in the mixture layer depends on the dispersion state of the active material and conductive carbon material in the mixture ink and the dispersion state of the conductive carbon material in the composition for forming the underlayer. It is related to the state and the distribution state of the conductive carbon material in the underlayer, and affects the physical properties of the electrode and thus the battery performance.

  Therefore, dispersion of the active material and the conductive carbon material is an important issue. In particular, a carbon material excellent in electrical conductivity has a high structure and specific surface area, and therefore has a strong cohesive force, and it is difficult to uniformly mix and disperse it in a composite ink or an underlayer forming composition.

  If the dispersibility and particle size of the conductive carbon material are insufficiently controlled, a uniform conductive network is not formed, so that the internal resistance of the electrode cannot be reduced, and as a result, the performance of the electrode material can be fully exploited. There is a problem of not.

  In addition, the composite ink and the composition for forming the underlayer are required to have appropriate fluidity to enable coating on the surface of the metal foil functioning as a current collector. Furthermore, in order to form a composite material layer or a base layer having a surface that is as flat as possible and having a uniform thickness, the composite ink or the base layer forming composition is required to have an appropriate viscosity. In the case of applying the mixture ink after forming the underlayer, solvent resistance is also required for the underlayer in order to form the mixture layer.

  On the other hand, the composite layer formed from the composite ink and the base layer formed from the composition for forming the base layer, after being formed, can be cut into pieces of the desired size and shape together with the metal foil as the base material. Or punched. Therefore, the composite material layer and the base layer are required to have hardness that is not damaged and adhesion that does not crack or peel off by cutting or punching.

  The electrode adhesion is important because it greatly affects the performance of the electricity storage device.

  Taking lithium-ion batteries as an example, if the electrode adhesion is poor, the electrode structure collapses due to expansion / contraction of the active material due to lithium ion intercalation / deintercalation during charge / discharge Electrode peeling occurs, leading to deterioration of battery life.

  Batteries are used in a variety of environments, and are particularly susceptible to deterioration in high-temperature environments, so that they can withstand charge / discharge cycles while maintaining electrode adhesion and conductivity even in high-temperature environments. It becomes important.

  Patent Document 1 discloses an undercoat layer in which a conductive composition containing conductive carbon powder and a water-soluble binder such as an acrylic acid polymer is coated on a current collector of an electrode. Patent Document 2 discloses an undercoat forming composition prepared by mixing carbon black powder and butyl rubber in toluene. However, these compositions require further improvement in the adhesion to the current collector when used as an underlayer, and further improve the conductivity and coatability resulting from insufficient dispersion of the carbon material. Further, it is necessary to improve the solvent resistance necessary for applying the mixed ink to the upper layer, and further improvement has been desired for extending the life of the battery.

  Therefore, for these improvements, in Patent Documents 3 to 7, improvement of the binder by introducing a crosslinking component, use of carbon fibers having high conductivity, and a composition for forming a base using a dispersant are disclosed. It is disclosed that an electrode having high conductivity can be obtained by using it. However, the environment in which the battery is used varies, and in a battery that can withstand an environment such as a high temperature, further improvements in electrode adhesion and charge / discharge cycle characteristics are required.

Japanese Patent Laid-Open No. 62-160656 Japanese Unexamined Patent Publication No. Sho 63-121265 Japanese Patent Laid-Open No. 7-201362 JP 2006-140142 A JP 2007-226969 A Japanese Patent Laid-Open No. 2008-60060 International Publication No. WO2012 / 173072 Pamphlet

  An object of the present invention is a conductive composition excellent in conductivity and adhesion, and is a conductive composition for forming an electricity storage device excellent in charge / discharge cycle characteristics, including dispersibility of a conductive carbon material, It is to provide a conductive composition having excellent electrode adhesion.

The present invention is a conductive composition containing a conductive carbon material (A), a water-soluble resin binder (B), and a water-dispersible resin fine particle binder (C) in a specific range, and the conductive carbon material. Without impairing the dispersibility of (A), the adhesion and solvent resistance of the electrodes, and further the charge / discharge cycle characteristics of the electricity storage device can be improved.
That is, a conductive composition containing a conductive carbon material (A), a water-soluble resin binder (B), a water-dispersible resin fine particle binder (C), and an aqueous liquid medium (D). The total content of the conductive carbon material (A), the water-soluble resin binder (B) and the water-dispersible resin fine particle binder (C) is 100% by weight. 20-70% by weight,
The content of the water-soluble resin binder (B) is 40 to 95% by weight in the total solid content of 100% by weight of the water-soluble resin binder (B) and the water-dispersible resin fine particle binder (C). The present invention relates to a conductive composition.

  In addition, the present invention relates to the conductive composition, which is used for forming a base layer of an electrode for an electricity storage device.

  The present invention also relates to a current collector with an underlayer for an electricity storage device, which includes a current collector and an underlayer formed from the conductive composition.

  The present invention also provides an electricity storage device comprising a current collector, a base layer formed from the conductive composition, and a composite layer formed from an electrode forming composition containing an electrode active material and a binder. The present invention relates to an electrode.

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

  By containing the conductive carbon material (A), the water-soluble resin binder (B), and the water-dispersible resin fine particle binder (C) at a specific ratio, the conductive carbon material in the conductive composition A base layer having excellent adhesion to a current collector can be formed without impairing dispersibility, and an electricity storage device having good charge / discharge cycle characteristics can be provided even under harsh environments such as high temperatures where the electricity storage device is used. .

  An electrode for an electricity storage device can be obtained by various methods.

For example, on the surface of a current collector such as a metal foil,
(1) an ink-like composition containing an active material and a solvent (hereinafter referred to as composite ink),
(2) a mixed ink containing an active material, a conductive additive and a solvent;
(3) a mixed ink containing an active material, a binder and a solvent;
(4) A mixed ink containing an active material, a conductive additive, a binder and a solvent,
It can be used to form a composite layer and obtain an electrode.

  Alternatively, an underlayer is formed on the surface of the current collector of the metal foil using a composition for forming an underlayer containing a conductive carbon material and a liquid medium, and the above-mentioned composite ink is formed on the underlayer An electrode can also be obtained by forming a composite layer using (1) to (4) and other composite inks.

  In any case, it has been described in detail in the background art section that the dispersion state of the conductive carbon material and the adhesion of the electrodes influence the performance of the electricity storage device.

Therefore, the conductive composition of the present invention can be used to satisfactorily form an underlayer.
<Conductive composition>
As described above, the conductive composition of the present invention can be used for forming a base layer of an electricity storage device. The conductive composition contains a conductive carbon material (A), a water-soluble resin binder (B), a water-dispersible resin fine particle binder (C), and an aqueous liquid medium (D).

The proportion of the conductive carbon material (A) in the total solid content of the conductive composition is 20% by weight or more and 70% by weight or less, preferably 25% by weight or more and 60% by weight or less. If the amount of the conductive carbon material (A) is too small, the conductivity of the underlayer may not be maintained. On the other hand, if the amount of the conductive carbon material (A) is too large, the durability such as adhesion of the coating film may be obtained. May decrease.
The ratio of the water-soluble resin binder (B) to the total solid content of the water-soluble resin binder (B) and the water-dispersible resin fine particle binder (C) is 40% by weight or more and 95% by weight or less. If the proportion of the water-soluble resin binder (B) is too large, the adhesion of the electrode may be insufficient. On the other hand, if the proportion of the water-soluble resin binder (B) is too small, the solvent resistance is insufficient. In some cases, a good underlayer cannot be formed. It is very important to use the water-soluble resin binder (B) and the water-dispersible resin fine particle binder (C) in the above specific ratio in order to form a good underlayer.

  Moreover, although the appropriate viscosity of an electroconductive composition is based on the coating method of an electroconductive composition, generally it is preferable to set it as 10 mPa * s or more and 30,000 mPa * s or less.

  First, the conductive carbon material (A) will be described.

  The conductive carbon material (A) in the present invention is not particularly limited as long as it is a conductive carbon material, but graphite, carbon black, conductive carbon fiber (carbon nanotube, carbon nanofiber, carbon Fiber), fullerene, etc. can be used alone or in combination of two or more. From the viewpoint of conductivity, availability, and cost, it is preferable to use carbon black.

  Carbon black is a furnace black produced by continuously pyrolyzing a gas or liquid raw material in a reactor, especially ketjen black using ethylene heavy oil as a raw material. Channel black that has been rapidly cooled and precipitated, thermal black obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, and particularly various types such as acetylene black using acetylene gas as a raw material, or 2 More than one type can be used in combination. Ordinarily oxidized carbon black, hollow carbon and the like can also be used.

    The oxidation treatment of carbon is performed by treating carbon at a high temperature in the air or by secondary treatment with nitric acid, nitrogen dioxide, ozone, etc., for example, such as phenol group, quinone group, carboxyl group, carbonyl group. This is a treatment for directly introducing (covalently bonding) an oxygen-containing polar functional group to the carbon surface, and is generally performed to improve the dispersibility of carbon. However, since it is common for the conductivity of carbon to fall, so that the introduction amount of a functional group increases, it is preferable to use the carbon which has not been oxidized.

As the specific surface area of the carbon black used increases, the number of contact points between the carbon black particles increases, which is advantageous in reducing the internal resistance of the electrode. Specifically, the specific surface area (BET) determined from the amount of nitrogen adsorbed 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, more preferably 100 m ^2. / G or more and 1500 m ² / g or less are desirable. If carbon black having a specific surface area of less than 20 m ² / g is used, it may be difficult to obtain sufficient conductivity, and carbon black of more than 1500 m ² / g may be difficult to obtain from commercially available materials. is there.

  Further, the particle size of the carbon black to be used is preferably 0.005 to 1 μm, particularly preferably 0.01 to 0.2 μm in terms of primary particle size. However, the primary particle diameter here is an average of the particle diameters measured with an electron microscope or the like.

  The conductive carbon material (A) conductive composition and the dispersed particle size in the conductive composition are desirably refined to 0.03 μm or more and 5 μm or less. It may be difficult to produce a composition having a dispersed particle size of the carbon material as the conductive aid of less than 0.03 μm. In addition, when a composition having a dispersed particle size of the carbon material as the conductive auxiliary agent exceeding 2 μm is used, there may be problems such as variations in the material distribution of the composite coating film and variations in the resistance distribution of the electrodes. .

    The dispersed particle size referred to here is a particle size (D50) that is 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution. A particle size distribution meter such as a dynamic light scattering type particle size distribution meter ("Microtrack UPA" manufactured by Nikkiso Co., Ltd.).

  Examples of commercially available carbon black include Toka Black # 4300, # 4400, # 4500, # 5500 (Tokai Carbon Co., Furnace Black), Printex L and the like (Degussa Co., Furnace Black), Raven 7000, 5750, 5250, 5000 ULTRA III, 5000 ULTRA, etc., Conductex SC ULTRA, Conductex 975 ULTRA, etc., PUER BLACK100, 115, 205, etc. (manufactured by Colombian, Furnace Black), # 2350, # 2400B, # 2600B, # 30050B, # 3030B, # 3030B, # 3030B # 3350B, # 3400B, # 5400B etc. (Mitsubishi Chemical Co., Furnace Black), MONARCH1400, 1300, 900, VulcanXC- 2R, BlackPearls2000, etc. (Cabot, Furnace Black), Ensaco 250G, Ensaco 260G, Ensaco 350G, SuperP-Li (manufactured by TIMCAL), Ketjen Black EC-300J, EC-600JD (manufactured by Akzo), Denka Black, Denka Black HS Examples of graphite such as -100, FX-35 (manufactured by Denki Kagaku Kogyo Co., Ltd., acetylene black) include natural graphite such as artificial graphite, flake graphite, massive graphite, and earth graphite, but are not limited thereto. They may be used in combination of two or more.

  As the conductive carbon fibers, those obtained by firing from petroleum-derived raw materials are preferable, but those obtained by firing from plant-derived raw materials can also be used. For example, VGCF manufactured by Showa Denko Co., Ltd. manufactured with petroleum-derived raw materials can be mentioned.

  Next, the water-soluble resin binder (B) will be described.

  The water-soluble resin binder (B) of the present invention is 1 g of water-soluble resin binder (B) in 99 g of water at 25 ° C., stirred and left at 25 ° C. for 24 hours. The binder is completely soluble.

  The water-soluble resin binder (B) is not particularly limited as long as it is a water-soluble resin as described above. For example, acrylic resin, polyurethane resin, polyester resin, polyamide resin, polyimide resin, polyallylamine resin , Polymer compounds including polysaccharide resins such as phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicon resin, fluorine resin, carboxymethyl cellulose. Moreover, if it is water-soluble, the modified substance, mixture, or copolymer of these resin may be sufficient. These binders can be used alone or in combination.

  Next, the water dispersible resin fine particle binder (C) will be described.

  The water-dispersible resin fine particle binder (C) of the present invention is generally called an aqueous emulsion, and the binder resin is not dissolved in water but is dispersed in the form of fine particles.

  The emulsion to be used is not particularly limited, and examples thereof include (meth) acrylic emulsions, nitrile emulsions, urethane emulsions, diene emulsions (such as SBR), and fluorine emulsions (such as PVDF and PTFE). Unlike the water-soluble polymer, the emulsion preferably has excellent binding properties between particles and flexibility (film flexibility).

(Particle structure of emulsion)
Further, the particle structure of the water-dispersible resin fine particle binder (C) of the present invention can be a multilayer structure, so-called core-shell particles. For example, it is possible to localize a resin in which a monomer having a functional group is mainly polymerized in the core part or the shell part, or to provide a difference in Tg or composition between the core and the shell, thereby improving the curability and drying. Property, film formability, and mechanical strength of the binder can be improved.

(Particle size of emulsion)
The average particle size of the water-dispersible resin fine particle binder (C) of the present invention is preferably 10 to 500 nm, and more preferably 10 to 300 nm, from the viewpoint of binding properties and particle stability. Further, when a large amount of coarse particles exceeding 1 μm are contained, the stability of the particles is impaired, so that the coarse particles exceeding 1 μm are preferably at most 5% or less. In addition, the average particle diameter in the present invention represents a volume average particle diameter and can be measured by a dynamic light scattering method.

  The average particle diameter can be measured by the dynamic light scattering method as follows. The cross-linked resin fine particle dispersion is diluted with water 200 to 1000 times depending on the solid content. About 5 ml of the diluted solution is injected into a cell of a measuring device [Microtrack manufactured by Nikkiso Co., Ltd.], and the measurement is performed after inputting the solvent (water in the present invention) and the refractive index conditions of the resin according to the sample. The peak of the volume particle size distribution data (histogram) obtained at this time is defined as the average particle size of the present invention.

When using a (meth) acrylic-type emulsion, it is preferable to contain the crosslinked resin fine particle demonstrated below. The crosslinked resin fine particles are resin fine particles having an internal cross-linked structure (three-dimensional cross-linked structure), and it is important that the fine particles are cross-linked inside the particles. When the cross-linked resin fine particles have a cross-linked structure, the electrolytic solution elution resistance can be secured, and the effect can be enhanced by adjusting the cross-linking inside the particles. Further, when the cross-linked resin fine particles contain a specific functional group, it is possible to contribute to adhesion with the current collector or the electrode. Furthermore, the conductive composition excellent in durability of the electrical storage device can be obtained by adjusting the amount of the crosslinked structure and the functional group.
In addition, cross-linking of particles (cross-particle cross-linking) can be used together for cross-linking, but in this case, since a cross-linking agent is added later, leakage of the cross-linking agent component into the electrolyte or electrode preparation There may be variations. For this reason, it is necessary to use a crosslinking agent to such an extent that the electrolyte solution resistance is not impaired.

The crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are obtained by emulsion polymerization of an ethylenically unsaturated monomer in water in the presence of a surfactant with a radical polymerization initiator. Resin fine particles. The (meth) acrylic emulsion suitably used in the present invention is preferably obtained by emulsion polymerization of an ethylenically unsaturated monomer containing the following monomers (c1) and (c2) in the following proportions.
(C1) From the group consisting of an ethylenically unsaturated monomer (c1) having a monofunctional or polyfunctional alkoxysilyl group and a monomer (c2) having two or more ethylenically unsaturated groups in one molecule At least one monomer selected: 0.1 to 5% by weight
(C2) Ethylenically unsaturated monomers (c3) other than the monomers (c1) to (c2): 95 to 99.9% by weight
(However, the total of the above (c1) to (c3) is 100% by weight)

  Of the ethylenically unsaturated monomers constituting the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention, (c1) and (c3) are in one molecule unless otherwise specified. A monomer having one ethylenically unsaturated group is shown.

<About the monomer group (C1)>
The functional group (alkoxysilyl group, ethylenically unsaturated group) possessed by the monomer contained in the monomer group (C1) is a self-crosslinking reactive functional group, and is mainly used for particle internal crosslinking during particle synthesis. Has the effect of forming. Electrolytic solution resistance can be improved by sufficiently carrying out internal crosslinking of the particles. Therefore, it is possible to obtain crosslinked resin fine particles by using a monomer contained in the monomer group (C1). In addition, by sufficiently carrying out particle crosslinking, the resistance to electrolytic solution can be improved.

  Examples of the monomer (c1) having one ethylenically unsaturated group and an alkoxysilyl group in one molecule include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ- Methacryloxypropyl tributoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-acryloxypropylmethyl Dimethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-acryloxymethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, etc. It is.

  Examples of the monomer (c2) having two or more ethylenically unsaturated groups in one molecule include allyl (meth) acrylate, 1-methylallyl (meth) acrylate, and 2-methylallyl (meth) acrylate. 1-butenyl (meth) acrylate, 2-butenyl (meth) acrylate, 3-butenyl (meth) acrylate, 1,3-methyl-3-butenyl (meth) acrylate, 2- (meth) acrylate 2- Chloroallyl, 3-chloroallyl (meth) acrylate, o-allylphenyl (meth) acrylate, 2- (allyloxy) ethyl (meth) acrylate, allyl lactyl (meth) acrylate, citronellyl (meth) acrylate, (meth) Geranyl acrylate, rosinyl (meth) acrylate, cinnamyl (meth) acrylate, diallyl maleate, diallyl itaconic acid (Meth) acrylic acid esters containing ethylenically unsaturated groups such as vinyl (meth) acrylate, vinyl crotonate, vinyl oleate, vinyl linolenate, 2- (2′-vinyloxyethoxy) ethyl (meth) acrylate ; Ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, diacryl Multifunctional (meth) acrylic acid esters such as 1,1,1-trishydroxymethylethane acid, 1,1,1-trishydroxymethylethane triacrylate, 1,1,1-trishydroxymethylpropanetriacrylic acid Divinylbenzene, divinyl adipate, etc. Vinyls; diallyl isophthalate, diallyl phthalate, etc. diallyl such as diallyl maleate and the like.

  The purpose of the alkoxysilyl group or ethylenically unsaturated group in the monomer (c1) or monomer (c2) is to introduce a cross-linked structure into the particle by self-condensation or polymerization mainly during the polymerization. However, a part of it may remain inside or on the surface after polymerization. The remaining alkoxysilyl group or ethylenically unsaturated group contributes to interparticle crosslinking of the binder composition. In particular, an alkoxysilyl group is preferable because it has an effect of improving adhesion to the current collector.

  In the present invention, the monomer contained in the monomer group (C1) is used in an amount of 0.1 to 5% by weight in the whole ethylenically unsaturated monomer (100% by weight in total) used for emulsion polymerization. It is characterized by that. Preferably it is 0.5 to 3 weight%. When the monomer contained in the monomer group (C1) is less than 0.1% by weight, the particles are not sufficiently cross-linked, and the resistance to electrolytic solution is deteriorated. On the other hand, if it exceeds 5% by weight, there will be a problem in the polymerization stability at the time of emulsion polymerization, or even if it can be polymerized, there will be a problem in the storage stability.

<About monomer group (C2)>
The crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are the monomer (c1) having one ethylenically unsaturated group and an alkoxysilyl group in one molecule described above, In addition to the monomer (c2) having two or more ethylenically unsaturated groups in one molecule, the monomer group (C2) is ethylenic other than the monomers (c1) and (c2). The monomer (c3) having an unsaturated group can be obtained by emulsion polymerization at the same time.

The monomer (c3) is not particularly limited as long as it is a monomer other than the monomers (c1) and (c2) and has an ethylenically unsaturated group.
Monomer (c4) having one ethylenically unsaturated group and monofunctional or polyfunctional epoxy group in one molecule, one ethylenically unsaturated group and monofunctional or polyfunctional amide group in one molecule And at least one monomer selected from the group consisting of a monomer (c5) having one ethylenically unsaturated group and a monofunctional or polyfunctional hydroxyl group in one molecule (c6) And the monomer (c7) having an ethylenically unsaturated group other than the monomer and the monomers (c1), (c2), and (c4) to (c6) can be used.
By using the monomers (c4) to (c6), an epoxy group, an amide group, or a hydroxyl group can be left in the particles or on the surface of the cross-linked resin fine particles. The physical properties of can be improved. In the monomers (c4) to (c6), the functional group tends to remain inside or on the surface of the particles even after the particle synthesis, and the adhesion effect to the current collector is large even in a small amount. Moreover, a part of them may be used for the crosslinking reaction, and by adjusting the degree of crosslinking of these functional groups, it is possible to balance the resistance to electrolytic solution and the adhesion.

  Examples of the monomer (c4) having one ethylenically unsaturated group and a monofunctional or polyfunctional epoxy group in one molecule include glycidyl (meth) acrylate and 3,4-epoxycyclohexyl (meth) acrylate. Etc.

  Examples of the monomer (c5) having one ethylenically unsaturated group and a monofunctional or polyfunctional amide group in one molecule include, for example, a primary amide group-containing ethylenically unsaturated monomer such as (meth) acrylamide. N-methylol acrylamide, N, N-di (methylol) acrylamide, alkylol (meth) acrylamides such as N-methylol-N-methoxymethyl (meth) acrylamide; N-methoxymethyl- (meth) acrylamide, Monoalkoxy (meth) acrylamides such as N-ethoxymethyl- (meth) acrylamide, N-propoxymethyl- (meth) acrylamide, N-butoxymethyl- (meth) acrylamide, N-pentoxymethyl- (meth) acrylamide; N, N-di (methoxymethyl) acrylamide, N-ethoxy Methyl-N-methoxymethylmethacrylamide, N, N-di (ethoxymethyl) acrylamide, N-ethoxymethyl-N-propoxymethylmethacrylamide, N, N-di (propoxymethyl) acrylamide, N-butoxymethyl-N- (Propoxymethyl) methacrylamide, N, N-di (butoxymethyl) acrylamide, N-butoxymethyl-N- (methoxymethyl) methacrylamide, N, N-di (pentoxymethyl) acrylamide, N-methoxymethyl-N Dialkoxy (meth) acrylamides such as (pentoxymethyl) methacrylamide; dialkylamino (meth) acrylamides such as N, N-dimethylaminopropylacrylamide and N, N-diethylaminopropylacrylamide; N, N- Methyl acrylamide, N, N-dialkyl such as diethyl acrylamide (meth) acrylamides; and diacetone (meth) keto group, such as acrylamide-containing (meth) acrylamides and the like.

  Examples of the monomer (c6) having one ethylenically unsaturated group and a monofunctional or polyfunctional hydroxyl group in one molecule include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. 4-hydroxybutyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid, glycerol mono (meth) acrylate, 4-hydroxyvinylbenzene, 1-ethynyl-1-cyclohexanol, allyl Examples include alcohol.

  Some of the functional groups of the monomers contained in the monomers (c4) to (c6) may react during particle polymerization and be used for intraparticle crosslinking. In the present invention, the monomer contained in the monomers (c4) to (c6) is 0.1 to 20% by weight in the whole ethylenically unsaturated monomer (100% by weight in total) used for emulsion polymerization. It is used. Preferably it is 1 to 15 weight%, Most preferably, it is 2 to 10 weight%. When the monomers (c4) to (c6) in the whole ethylenically unsaturated monomers (100% by weight in total) used for the emulsion polymerization are less than 0.1% by weight, the inside of the particles after polymerization or on the surface The amount of remaining functional groups is reduced, and cannot sufficiently contribute to the improvement of the adhesion of the current collector. On the other hand, if it exceeds 20% by weight, there will be a problem in the polymerization stability at the time of emulsion polymerization, or even if it can be polymerized, there will be a problem in the storage stability.

  The monomer (c7) is not particularly limited as long as it is a monomer having an ethylenically unsaturated group other than the monomers (c1), (c2), and (c4) to (c6). For example, a monomer (c8) having one ethylenically unsaturated group and an alkyl group having 8 to 18 carbon atoms in one molecule, one ethylenically unsaturated group in one molecule, and a cyclic structure And the monomer (c9). When the monomer (c8) and / or the monomer (c9) is used for the emulsion polymerization as the monomer (c7) (including other monomers as the monomer (c7)) The monomers (c8) and (c9) are all monomers having an ethylenically unsaturated group ((c1), (c2), (c4) to (c6) and (c7)). It is preferable that 30 to 95 weight% is contained in total. It is preferable to use the monomer (c8) or the monomer (c9) because the particle stability during particle synthesis and the resistance to electrolytic solution are excellent. If it is less than 30% by weight, the electrolyte solution resistance may be adversely affected. If it exceeds 95% by weight, the stability during particle synthesis will be adversely affected, or even if synthesis is possible, the temporal stability of the particles will be impaired. There is a case.

  Examples of the monomer (c8) having one ethylenically unsaturated group and an alkyl group having 8 to 18 carbon atoms in one molecule include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and myristyl. (Meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate and the like can be mentioned.

  Examples of the monomer (c9) having one ethylenically unsaturated group and a cyclic structure in one molecule include alicyclic ethylenically unsaturated monomers and aromatic ethylenically unsaturated monomers. It is done. Examples of the alicyclic ethylenically unsaturated monomer include cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, and examples of the aromatic ethylenically unsaturated monomer include benzyl (meth) acrylate. Phenoxyethyl (meth) acrylate, styrene, α-methylstyrene, 2-methylstyrene, chlorostyrene, allylbenzene, ethynylbenzene and the like.

  Examples of the monomer (c7) other than the monomer (c8) and the monomer (c9) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth). ) Alkyl group-containing ethylenically unsaturated monomers such as acrylate, pentyl (meth) acrylate, heptyl (meth) acrylate; nitrile group-containing ethylenically unsaturated monomers such as (meth) acrylonitrile; perfluoromethylmethyl (meta ) Acrylate, perfluoroethylmethyl (meth) acrylate, 2-perfluorobutylethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorooctylethyl (meth) acrylate, 2-perfluoroiso Nonylethyl (meth) acrylate, 2-par Fluorononylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, perfluoropropylpropyl (meth) acrylate, perfluorooctylpropyl (meth) acrylate, perfluorooctyl amyl (meth) acrylate, perfluorooctylun Perfluoroalkyl group-containing ethylenically unsaturated monomer having 1 to 20 carbon atoms such as decyl (meth) acrylate; perfluorobutylethylene, perfluorohexylethylene, perfluorooctylethylene, perfluorodecyl Perfluoroalkyl such as ethylene, perfluoroalkyl group-containing ethylenically unsaturated compounds such as alkylene; polyethylene glycol (meth) acrylate, methoxypolyethylene Glycol (meth) acrylate, ethoxypolyethyleneglycol (meth) acrylate, propoxypolyethyleneglycol (meth) acrylate, n-butoxypolyethyleneglycol (meth) acrylate, n-pentoxypolyethyleneglycol (meth) acrylate, phenoxypolyethyleneglycol (meth) acrylate , Polypropylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, propoxypolypropylene glycol (meth) acrylate, n-butoxypolypropylene glycol (meth) acrylate, n-pentoxypolypropylene glycol (meta ) Acrylate, phenoxy polypropylene glycol (Meth) acrylate, polytetramethylene glycol (meth) acrylate, methoxypolytetramethylene glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, hexaethylene glycol (meth) acrylate, methoxyhexaethylene glycol (meth) acrylate Ethylenically unsaturated compounds having a polyether chain such as: ethylenically unsaturated compounds having a polyester chain such as a lactone-modified (meth) acrylate; (meth) acrylic acid dimethylaminoethyl methyl chloride salt, trimethyl-3- (1- (Meth) acrylamide-1,1-dimethylpropyl) ammonium chloride, trimethyl-3- (1- (meth) acrylamidopropyl) ammonium chloride, and trime Quaternary ammonium base-containing ethylenically unsaturated compounds such as ru-3- (1- (meth) acrylamide-1,1-dimethylethyl) ammonium chloride; vinyl acetate, vinyl butyrate, vinyl propionate, vinyl hexanoate, caprylic acid Fatty acid vinyl compounds such as vinyl, vinyl laurate, vinyl palmitate and vinyl stearate; Vinyl ether ethylenically unsaturated monomers such as butyl vinyl ether and ethyl vinyl ether; 1-hexene, 1-octene, 1-decene, 1 Α-olefinic ethylenically unsaturated monomers such as dodecene, 1-tetradecene and 1-hexadecene; allyl monomers such as allyl acetate and allyl cyanide; vinyl such as vinyl cyanide, vinylcyclohexane and vinylmethylketone Monomer; acetylene, ethynyl Examples include ethynyl monomers such as toluene.

  Examples of the monomer (c7) other than the monomer (c8) and monomer (c9) include maleic acid, fumaric acid, itaconic acid, citraconic acid, and alkyl or alkenyl monoesters thereof. , Phthalic acid β- (meth) acryloxyethyl monoester, isophthalic acid β- (meth) acryloxyethyl monoester, terephthalic acid β- (meth) acryloxyethyl monoester, succinic acid β- (meth) acryloxyethyl Carboxyl group-containing ethylenically unsaturated monomers such as monoesters, acrylic acid, methacrylic acid, crotonic acid and cinnamic acid; Tertiary butyl group-containing ethylenically unsaturated monomers such as tertiary butyl (meth) acrylate; Sulfonic acid group-containing ethylenically unsaturated monomers such as vinyl sulfonic acid and styrene sulfonic acid; -Hydroxyethyl) methacrylate unsaturated phosphate-containing ethylenically unsaturated monomers; diacetone (meth) acrylamide, acrolein, N-vinylformamide, vinyl methyl ketone, vinyl ethyl ketone, acetoacetoxyethyl (meth) Keto group-containing ethylenically unsaturated monomers such as acrylate, acetoacetoxypropyl (meth) acrylate, acetoacetoxybutyl (meth) acrylate (monomers having one ethylenically unsaturated group and a keto group in one molecule) Body).

  When a keto group-containing ethylenically unsaturated monomer is used as the monomer (c7), a polyfunctional hydrazide compound having two or more hydrazide groups capable of reacting with a keto group as a crosslinking agent is mixed with the binder composition. A tough coating film can be obtained by crosslinking between a keto group and a hydrazide group. This has excellent electrolytic solution resistance and binding properties. Furthermore, since it is possible to achieve both durability and flexibility in a high-temperature environment due to repeated charge and discharge and heat generation, it is possible to obtain a long-life electricity storage device with reduced discharge capacity reduction in the charge and discharge cycle.

  Among the monomers (c7), an ethylenically unsaturated monomer having a carboxyl group, a tertiary butyl group (tertiary butanol is removed by heat to form a carboxyl group), a sulfonic acid group, and a phosphoric acid group. The resin fine particles obtained by copolymerization of the body have the effect of improving the physical properties such as the adhesion of the current collector, while the functional groups remain in the particles and on the surface even after polymerization, and at the same time agglomeration during synthesis Can be prevented, and the stability of the particles after synthesis may be maintained.

  A part of the carboxyl group, tertiary butyl group, sulfonic acid group, and phosphoric acid group may react during polymerization and be used for intraparticle crosslinking. In the case of using a monomer containing a carboxyl group, a tertiary butyl group, a sulfonic acid group, and a phosphoric acid group, the total amount of ethylenically unsaturated monomers used in the emulsion polymerization (100% by weight in total) is 0. The content is preferably 1 to 10% by weight, more preferably 1 to 5% by weight. When the monomer containing a carboxyl group, tertiary butyl group, sulfonic acid group, and phosphoric acid group is less than 0.1% by weight, the stability of the particles may be deteriorated. On the other hand, when the content exceeds 10% by weight, the hydrophilicity of the binder composition becomes too strong, and the electrolytic solution resistance may deteriorate. Furthermore, these functional groups may react during drying and be used for cross-linking within or between particles.

  For example, a carboxyl group can react with an epoxy group during polymerization and drying to introduce a crosslinked structure into the resin fine particles. Similarly, a tertiary butyl group can react with an epoxy group in the same manner as described above since tertiary butyl alcohol is generated and a carboxyl group is formed when heat of a certain temperature or higher is applied.

  These monomers (c7) are used in combination of two or more of the above-mentioned monomers in order to adjust the polymerization stability and glass transition temperature of the particles, as well as the film formability and film properties. Can be used. Further, for example, by using (meth) acrylonitrile in combination, there is an effect that rubber elasticity is exhibited.

<Method for Producing Crosslinked Resin Fine Particles in (Meth) Acrylic Emulsion Suitable for Use in the Present Invention>
The crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are synthesized by a conventionally known emulsion polymerization method.

<Emulsifier used in emulsion polymerization>
As the emulsifier used in the emulsion polymerization in the present invention, a conventionally known one such as a reactive emulsifier having an ethylenically unsaturated group or a non-reactive emulsifier having no ethylenically unsaturated group may be arbitrarily used. it can.

  Reactive emulsifiers having an ethylenically unsaturated group can be further roughly classified into anionic and nonionic nonionic ones. Especially when anionic reactive emulsifier or nonionic reactive emulsifier having an ethylenically unsaturated group is used, the dispersion particle size of the copolymer becomes finer and the particle size distribution becomes narrower, so it is used as a binder for secondary battery electrodes. In this case, the resistance to electrolytic solution can be improved. These anionic reactive emulsifiers or nonionic reactive emulsifiers having an ethylenically unsaturated group may be used singly or in combination.

  Specific examples of the anionic reactive emulsifier having an ethylenically unsaturated group are illustrated below, but the emulsifiers that can be used in the present invention are not limited to those described below.

  As an emulsifier, an alkyl ether type (as commercial products, for example, Aqualon KH-05, KH-10, KH-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Adeka Soap SR-10N, SR-20N manufactured by ADEKA Co., Ltd., Laterum PD-104 manufactured by Kao Corporation); sulfosuccinic acid ester system (for example, LATEMUL S-120, S-120A, S-180P, S-180A manufactured by Kao Corporation, Elemiol manufactured by Sanyo Chemical Co., Ltd.) JS-2 etc.); alkylphenyl ether type or alkylphenyl ester type (commercially available products include, for example, Aqualon H-2855A, H-3855B, H-3855C, H-3856, HS-05 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) , HS-10, HS-20, HS-30, ADEKA Corporation ADEKA rear SDX-222, SDX-223, SDX-232, SDX-233, SDX-259, SE-10N, SE-20N, etc.) (meth) acrylate sulfate ester (commercially available products include, for example, Japanese emulsifiers) Antox MS-60, MS-2N, Sanyo Kasei Kogyo Co., Ltd., Eleminol RS-30, etc.); Phosphate ester (for example, H-3330PL, Daiichi Kogyo Seiyaku Co., Ltd., stock) Adeka Soap PP-70 manufactured by the company ADEKA).

  Nonionic reactive emulsifiers that can be used in the present invention include, for example, alkyl ether-based (commercially available products such as Adeka Soap ER-10, ER-20, ER-30, ER-40, manufactured by ADEKA Corporation, Laterum PD-420, PD-430, PD-450, etc. manufactured by Kao Corporation; alkyl phenyl ethers or alkyl phenyl esters (for example, Aqualon RN-10, RN- manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 20, RN-30, RN-50, ADEKA Corporation ADEKA rear soap NE-10, NE-20, NE-30, NE-40, etc.); (meth) acrylate sulfate ester system (commercially available products include, for example, RMA-564, RMA-568, RMA-1114, etc. manufactured by Nippon Emulsifier Co., Ltd.) .

  When the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention are obtained by emulsion polymerization, together with the above-described reactive emulsifier having an ethylenically unsaturated group, an ethylenically unsaturated group may be used. Non-reactive emulsifiers that do not have any can be used in combination. Non-reactive emulsifiers can be broadly classified into non-reactive anionic emulsifiers and non-reactive nonionic emulsifiers.

  Examples of non-reactive nonionic emulsifiers include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene alkyl such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether Sorbitan monolaurate, sorbitan monostearate, sorbitan higher fatty acid esters such as sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaurate, Polyoxyethylene higher fatty acid esters such as polyoxyethylene monostearate; oleic acid monoglyceride, stearic acid monoglyceride Glycerine higher fatty acid esters such as chloride, polyoxyethylene-polyoxypropylene block copolymers, and the like can be exemplified polyoxyethylene distyrenated phenyl ether.

  Examples of non-reactive anionic emulsifiers include higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfate esters such as sodium lauryl sulfate; polyoxyethylene lauryl ether Polyoxyethylene alkyl ether sulfates such as sodium sulfate; polyoxyethylene alkylaryl ether sulfates such as polyoxyethylene nonylphenyl ether sodium sulfate; sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, polyoxyethylene lauryl sulfosuccinic acid Alkylsulfosuccinic acid ester salts such as sodium and derivatives thereof; polyoxyethylene distyrenated phenyl ether And the like can be exemplified sulfuric ester salts.

  The usage-amount of the emulsifier used in this invention is not necessarily limited, It can select suitably according to the physical property calculated | required when crosslinked type resin microparticles are used as a final binder. For example, the amount of the emulsifier is usually preferably 0.1 to 30 parts by weight, more preferably 0.3 to 20 parts by weight, based on 100 parts by weight of the total of ethylenically unsaturated monomers. More preferably, it is in the range of 5 to 10 parts by weight.

  In emulsion polymerization of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention, a water-soluble protective colloid can be used in combination. Examples of water-soluble protective colloids include polyvinyl alcohols such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose salt; Examples thereof include saccharides, and these can be used alone or in a combination of plural kinds. The amount of the water-soluble protective colloid used is 0.1 to 5 parts by weight, more preferably 0.5 to 2 parts by weight, per 100 parts by weight of the total of ethylenically unsaturated monomers.

<Aqueous medium used in emulsion polymerization>
Examples of the aqueous medium used in the emulsion polymerization of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention include water, and a hydrophilic organic solvent does not impair the object of the present invention. Can be used in

<Polymerization initiator used in emulsion polymerization>
The polymerization initiator used for obtaining the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention is not particularly limited as long as it has the ability to initiate radical polymerization, and is known in the art. Oil-soluble polymerization initiators and water-soluble polymerization initiators can be used.

  The oil-soluble polymerization initiator is not particularly limited, and examples thereof include benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl hydroperoxide, tert-butyl peroxy (2-ethylhexanoate), and tert-butyl peroxide. Organic peroxides such as oxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4- Examples thereof include azobis compounds such as dimethylvaleronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1′-azobiscyclohexane-1-carbonitrile. These can be used alone or in combination of two or more. These polymerization initiators are preferably used in an amount of 0.1 to 10.0 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated monomer.

  In the present invention, it is preferable to use a water-soluble polymerization initiator. For example, ammonium persulfate, potassium persulfate, hydrogen peroxide, 2,2′-azobis (2-methylpropionamidine) dihydrochloride and the like are conventionally known. A thing can be used conveniently. Moreover, when performing emulsion polymerization, a reducing agent can be used together with a polymerization initiator if desired. Thereby, it becomes easy to accelerate the emulsion polymerization rate or to perform the emulsion polymerization at a low temperature. Examples of such a reducing agent include reducing organic compounds such as metal salts such as ascorbic acid, ersorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfoxylate, sodium thiosulfate, sodium sulfite, sodium bisulfite, Examples include reducing inorganic compounds such as sodium bisulfite, ferrous chloride, Rongalite, thiourea dioxide, and the like. These reducing agents are preferably used in an amount of 0.05 to 5.0 parts by weight with respect to 100 parts by weight of the total ethylenically unsaturated monomer.

<Conditions for emulsion polymerization>
In addition, it can superpose | polymerize by a photochemical reaction, radiation irradiation, etc. irrespective of an above described polymerization initiator. The polymerization temperature is not less than the polymerization start temperature of each polymerization initiator. For example, in the case of a peroxide-based polymerization initiator, it may be usually about 70 ° C. The polymerization time is not particularly limited, but is usually 2 to 24 hours.

<Other materials used for reaction>
Further, if necessary, sodium acetate, sodium citrate, sodium bicarbonate, etc. as a buffering agent, and octyl mercaptan, 2-ethylhexyl thioglycolate, octyl thioglycolate, stearyl mercaptan, lauryl mercaptan as a chain transfer agent A suitable amount of mercaptans such as t-dodecyl mercaptan can be used.

  When a monomer having an acidic functional group such as a carboxyl group-containing ethylenically unsaturated monomer is used for polymerization of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention, Or can be neutralized with a basic compound after polymerization. When neutralizing, it can be neutralized with ammonia or alkylamines such as trimethylamine, triethylamine and butylamine; alcohol amines such as 2-dimethylaminoethanol, diethanolamine, triethanolamine and aminomethylpropanol; and a base such as morpholine. . However, it is a highly volatile base that is highly effective in drying, and preferred bases are aminomethylpropanol and ammonia.

<Characteristics of cross-linked resin fine particles in (meth) acrylic emulsion preferably used in the present invention>
(Glass-transition temperature)
Further, the glass transition temperature (hereinafter also referred to as Tg) of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention is preferably −50 to 70 ° C., more preferably −30 to 30 ° C. preferable. When Tg is less than −50 ° C., the binder excessively covers the electrode active material, and the impedance tends to increase. On the other hand, when Tg exceeds 70 ° C., the flexibility and tackiness of the binder become poor, and the adhesion of the conductive carbon material to the current collector and the moldability of the underlayer may be inferior. The glass transition temperature is a value obtained using a DSC (differential scanning calorimeter).

  The measurement of the glass transition temperature by DSC (differential scanning calorimeter) can be performed as follows. About 2 mg of resin obtained by drying the cross-linked resin fine particles is weighed on an aluminum pan, the test container is set on a DSC measurement holder, and the endothermic peak of the chart obtained under a temperature rising condition of 10 ° C./min is read. The peak temperature at this time is defined as the glass transition temperature of the present invention.

(Particle structure)
Moreover, the particle structure of the cross-linked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention can be a multi-layer structure, so-called core-shell particles. For example, it is possible to localize a resin in which a monomer having a functional group is mainly polymerized in the core part or the shell part, or to provide a difference in Tg or composition between the core and the shell, thereby improving the curability and drying. Property, film formability, and mechanical strength of the binder can be improved.

(Particle size)
The average particle diameter of the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention is preferably 10 to 500 nm from the viewpoint of the binding property of the electrode active material and the stability of the particles. 30 to 300 nm is more preferable. Further, when a large amount of coarse particles exceeding 1 μm are contained, the stability of the particles is impaired, so that the coarse particles exceeding 1 μm are preferably at most 5% by weight. In addition, the average particle diameter in the present invention represents a volume average particle diameter and can be measured by a dynamic light scattering method.

  The average particle diameter can be measured by the dynamic light scattering method as follows. The cross-linked resin fine particle dispersion is diluted with water 200 to 1000 times depending on the solid content. About 5 ml of the diluted solution is injected into a cell of a measuring device [Microtrack manufactured by Nikkiso Co., Ltd.], and the measurement is performed after inputting the solvent (water in the present invention) and the refractive index conditions of the resin according to the sample. The peak of the volume particle size distribution data (histogram) obtained at this time is defined as the average particle size of the present invention.

<Uncrosslinked compound (E) added to polymerized resin fine particles>
The (meth) acrylic emulsion suitably used in the present invention, in addition to the crosslinked resin fine particles, further includes an uncrosslinked epoxy group-containing compound, an uncrosslinked amide group-containing compound, an uncrosslinked hydroxyl group-containing compound, and It is preferable to include at least one uncrosslinked compound (E) selected from the group consisting of uncrosslinked oxazoline group-containing compounds [hereinafter sometimes referred to as compound (E)]. The compound (E) is a compound that does not dissolve in the aqueous liquid medium and is dispersed.

  The “uncrosslinked functional group-containing compound” which is the compound (E) is the inside of the (meth) acrylic emulsion suitably used in the present invention like the monomer contained in the monomer group (C1). Unlike a compound that forms a cross-linked structure (three-dimensional cross-linked structure), it refers to a compound that is added after emulsion polymerization (polymer formation) of resin fine particles (does not participate in internal cross-linking of resin fine particles). That is, “uncrosslinked” means that it is not involved in the formation of an internal crosslinked structure (three-dimensional crosslinked structure) of the (meth) acrylic emulsion suitably used in the present invention.

  The (meth) acrylic emulsion suitably used in the present invention has a cross-linked structure to ensure the resistance to electrolyte, and by using the compound (E), an epoxy group in the compound (E), At least one functional group selected from an amide group, a hydroxyl group, and an oxazoline group can contribute to adhesion with the current collector or the electrode. Furthermore, the conductive composition excellent in durability of the electrical storage device can be obtained by adjusting the amount of the crosslinked structure and the functional group.

  The crosslinked resin fine particles in the (meth) acrylic emulsion preferably used in the present invention must be crosslinked inside the particles. Electrolytic solution resistance can be ensured by appropriately adjusting the crosslinking inside the particles. Furthermore, the functional group-containing crosslinked resin fine particles are at least one selected from the group consisting of an uncrosslinked epoxy group-containing compound, an uncrosslinked amide group-containing compound, an uncrosslinked hydroxyl group-containing compound, and an uncrosslinked oxazoline group-containing compound. By adding the uncrosslinked compound (E), an epoxy group, an amide group, a hydroxyl group, or an oxazoline group acts on the current collector, and the adhesion to the current collector or the electrode can be effectively improved. Since the functional group contained in the compound (E) is stable by heat during long-term storage or electrode production, the effect of adhesion to the current collector is large even when used in a small amount. Furthermore, it is excellent in storage stability. The compound (E) may react with the functional group in the cross-linked resin fine particles for the purpose of adjusting the flexibility and the electrolytic solution resistance of the binder. When the functional group in the compound (E) is excessively used for the reaction, the functional group capable of interacting with the current collector or the electrode is decreased. For this reason, the reaction between the crosslinked resin fine particles in the (meth) acrylic emulsion suitably used in the present invention and the compound (E) needs to be at a level that does not impair the adhesion to the current collector or the electrode. is there. Further, when a part of the functional group contained in the compound (E) is used for the crosslinking reaction [when the compound (E) is a polyfunctional compound], by adjusting the degree of crosslinking of these functional groups, It is possible to balance the resistance to electrolytic solution and the adhesion.

<Uncrosslinked epoxy group-containing compound>
Examples of the uncrosslinked epoxy group-containing compound include epoxy group-containing ethylenically unsaturated monomers such as glycidyl (meth) acrylate and 3,4-epoxycyclohexyl (meth) acrylate; Radical polymerization resins obtained by polymerizing ethylenically unsaturated monomers containing monomers; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol Diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) Cyclohexane Polyfunctional epoxy compounds; bisphenol A- epichlorohydrin epoxy resins, and epoxy resins such as bisphenol F- epichlorohydrin type epoxy resin.

  Among epoxy group-containing compounds, in particular, epoxy resins such as bisphenol A-epichlorohydrin type epoxy resins and bisphenol F-epichlorohydrin type epoxy resins, and ethylenically unsaturated monomers containing epoxy group-containing ethylenically unsaturated monomers. A radical polymerization resin obtained by polymerizing a saturated monomer is preferred. The epoxy resin can be expected to have a synergistic effect of improving the electrolytic solution resistance by having a bisphenol skeleton and improving the adhesion of the current collector by a hydroxyl group contained in the skeleton. In addition, the radical polymerization resin obtained by polymerizing an ethylenically unsaturated monomer containing an epoxy group-containing ethylenically unsaturated monomer has a higher adhesion to the current collector by having more epoxy groups in the resin skeleton. In addition, since it is a resin, an effect of improving the resistance to electrolytic solution can be expected as compared with the monomer.

<Uncrosslinked amide group-containing compound>
As an uncrosslinked amide group-containing compound, for example, a primary amide group-containing compound such as (meth) acrylamide; N-methylolacrylamide, N, N-di (methylol) acrylamide, N-methylol-N-methoxymethyl (meta) ) Alkylol (meth) acrylamide compounds such as acrylamide; N-methoxymethyl- (meth) acrylamide, N-ethoxymethyl- (meth) acrylamide, N-propoxymethyl- (meth) acrylamide, N-butoxymethyl- (meta ) Monoalkoxy (meth) acrylamide compounds such as acrylamide and N-pentoxymethyl- (meth) acrylamide; N, N-di (methoxymethyl) acrylamide, N-ethoxymethyl-N-methoxymethylmethacrylamide, N, N -Di (Etoki Methyl) acrylamide, N-ethoxymethyl-N-propoxymethylmethacrylamide, N, N-di (propoxymethyl) acrylamide, N-butoxymethyl-N- (propoxymethyl) methacrylamide, N, N-di (butoxymethyl) Dialkoxy (meth) acrylamides such as acrylamide, N-butoxymethyl-N- (methoxymethyl) methacrylamide, N, N-di (pentoxymethyl) acrylamide, N-methoxymethyl-N- (pentoxymethyl) methacrylamide Compounds; dialkylamino (meth) acrylamide compounds such as N, N-dimethylaminopropylacrylamide and N, N-diethylaminopropylacrylamide; N, N-dimethylacrylamide and N, N-diethylacrylamide Any dialkyl (meth) acrylamide compound; keto group-containing (meth) acrylamide compound such as diacetone (meth) acrylamide or the like, and the above amide group-containing ethylenically unsaturated monomers; Examples thereof include a radical polymerization resin obtained by polymerizing an ethylenically unsaturated monomer containing a monomer.

  Among the amide group-containing compounds, radical polymerization resins obtained by polymerizing ethylenically unsaturated monomers including amide group-containing ethylenically unsaturated monomers such as acrylamide are particularly preferable. By having more amide groups in the resin skeleton, it is possible to improve the current collector adhesion, and by using the resin, the effect of improving the resistance to electrolytic solution compared to the monomer can be expected.

<Uncrosslinked hydroxyl group-containing compound>
Examples of the uncrosslinked hydroxyl group-containing compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate 4-hydroxyvinylbenzene, Hydroxyl group-containing ethylenically unsaturated monomers such as 1-ethynyl-1-cyclohexanol and allyl alcohol; radical polymerization obtained by polymerizing ethylenically unsaturated monomers containing the hydroxyl group-containing ethylenically unsaturated monomers Resins: linear aliphatic diols such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol; propylene glycol, neopentyl glycol 3-methyl-1,5 Pentanediol, 2,2-branched aliphatic diols such as diethyl-1,3-propanediol; and 1,4-bis cyclic diol such as (hydroxymethyl) cyclohexane.

  Among the hydroxyl group-containing compounds, radical polymerization resins obtained by polymerizing ethylenically unsaturated monomers including a hydroxyl group-containing ethylenically unsaturated monomer or cyclic diols are particularly preferable. The radical polymerization resin obtained by polymerizing ethylenically unsaturated monomers including hydroxyl group-containing ethylenically unsaturated monomers improves current collector adhesion by having more hydroxyl groups in the resin skeleton. In addition, the resin can be expected to have an effect of improving the resistance to electrolytic solution compared to the monomer. Moreover, cyclic diols can be expected to have an effect of improving the resistance to electrolytic solution by having a cyclic structure in the skeleton.

<Uncrosslinked oxazoline group-containing compound>
Examples of the uncrosslinked oxazoline group-containing compound include 2′-methylenebis (2-oxazoline), 2,2′-ethylenebis (2-oxazoline), and 2,2′-ethylenebis (4-methyl-2-oxazoline). ), 2,2′-propylenebis (2-oxazoline), 2,2′-tetramethylenebis (2-oxazoline), 2,2′-hexamethylenebis (2-oxazoline), 2,2′-octamethylene Bis (2-oxazoline), 2,2′-p-phenylenebis (2-oxazoline), 2,2′-p-phenylenebis (4,4′-dimethyl-2-oxazoline), 2,2′-p -Phenylenebis (4-methyl-2-oxazoline), 2,2'-p-phenylenebis (4-phenyl-2-oxazoline), 2,2'-m-phenylenebis (2-oxazoline), 2 , 2′-m-phenylenebis (4-methyl-2-oxazoline), 2,2′-m-phenylenebis (4,4′-dimethyl-2-oxazoline), 2,2′-m-phenylenebis ( 4-phenylenebis-2-oxazoline), 2,2′-o-phenylenebis (2-oxazoline), 2,2′-o-phenylenebis (4-methyl-2-oxazoline), 2,2′-bis (2-oxazoline), 2,2′-bis (4-methyl-2-oxazoline), 2,2′-bis (4-ethyl-2-oxazoline), 2,2′-bis (4-phenyl-2) -Oxazoline), and further an oxazoline group-containing radical polymerization resin.

  Among oxazoline group-containing compounds, in particular, phenylene bis-type oxazoline compounds such as 2′-p-phenylenebis (2-oxazoline), or ethylenically unsaturated monomers containing an oxazoline group-containing ethylenically unsaturated monomer A radical polymerization resin obtained by polymerizing is preferred. The phenylenebis type oxazoline compound has an effect of improving the resistance to electrolytic solution by having a phenyl group in the skeleton. In addition, a radical polymerization resin obtained by polymerizing an ethylenically unsaturated monomer containing an oxazoline group-containing ethylenically unsaturated monomer has a current collector adhesion by having more oxazoline groups in the resin skeleton. In addition, by using a resin, the resistance to an electrolytic solution can be improved as compared with a monomer.

<Addition amount of compound (E), molecular weight>
The compound (E) is preferably added in an amount of 0.1 to 50 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the solid content of the crosslinked resin fine particles. When the addition amount of the compound (E) is less than 0.1 parts by weight, the amount of the functional group contributing to the adhesion of the current collector is decreased, and may not be able to sufficiently contribute to the improvement of the adhesion of the current collector. On the other hand, if it exceeds 50 parts by weight, the binder performance may be adversely affected such as leakage of the compound (E) into the electrolyte. Furthermore, two or more types of compounds (E) can be used in combination.

  Although the molecular weight of a compound (E) is not specifically limited, It is preferable that a weight average molecular weight is 1,000-1,000,000, Furthermore, 5,000-500,000 are more preferable. If the weight average molecular weight is less than 1,000, the adhesion effect to the current collector may not be sufficient, and if the weight average molecular weight exceeds 1,000,000, the viscosity of the compound may increase. There may be a case where handling properties at the time of electrode preparation are deteriorated. In addition, the said weight average molecular weight is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

Next, the aqueous liquid medium (D) will be described.
As the aqueous liquid medium (D) used in the present invention, it is preferable to use water, but if necessary, for example, a liquid medium compatible with water in order to improve the coating property to the current collector. May be used.
Liquid media compatible with water include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, and phosphoric acid esters , Ethers, nitriles and the like, and may be used as long as they are compatible with water.

  Furthermore, a film-forming auxiliary, an antifoaming agent, a leveling agent, a preservative, a pH adjusting agent, a viscosity adjusting agent and the like can be blended with the conductive composition as necessary.

  In addition, since the conductive composition of the present invention can also be used for forming a base layer of an electrode for an electricity storage device, the reaction between impurities in the electrode and the electrolytic solution is performed for the purpose of suppressing charge / discharge cycle deterioration of the electricity storage device. You may add the material which adsorb | sucks or consumes the acid to produce | generate.

The material that adsorbs the acid generated by the reaction of the electrolytic solution is not particularly limited. For example, magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), boron oxide (B ₂ O ₃ ), gallium oxide (Ga) ₂ O ₃ ) and indium oxide (In ₂ O ₃ ).

  The material that consumes the acid generated by the reaction of the electrolytic solution is not particularly limited as long as the current collector is not corroded. For example, metal carbonates such as magnesium carbonate and calcium carbonate, sodium carboxylate, potassium carboxylate, sulfone Metal organic acid salts such as sodium silicate, potassium sulfonate, sodium benzoate, potassium benzoate, silicates such as sodium silicate, potassium silicate, aluminum silicate, magnesium silicate, silicon dioxide, magnesium hydroxide, etc. Alkaline hydroxides can be mentioned.

  Furthermore, when the conductive composition of the present invention is used for forming an underlayer of an electrode for an electricity storage device, gas is generated when the temperature exceeds a predetermined temperature for the purpose of suppressing thermal runaway when the electricity storage device is overcharged or short-circuited. A material having a positive temperature coefficient of resistance may be added.

  Examples of materials that generate gas when the temperature exceeds a predetermined temperature include carbonates such as lithium carbonate, zinc carbonate, lead carbonate, and strontium carbonate, and expanded graphite.

Examples of materials having a positive temperature coefficient of resistance include PTC materials and polymer PTC materials. The PTC material is a material whose resistance rapidly increases when the Curie temperature is exceeded. For example, BaTiMO ₂ (M is any of Cr, Pb, Ca, Sr, Ce, Mn, La, Mn, Y, Nb, and Nd. Or one or more elements).

  The polymer PTC material is a material that increases resistance by utilizing a change in the volume of the polymer due to heat. At low temperatures, a conductive path is formed by the conductive carbon material (A), but current flows. When the temperature becomes high, the polymer expands or contracts to block the conductive path, and the resistance can be increased. As such polymer PTC materials, polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyimide, polyamide, polytetrafluoroethylene, styrene butadiene rubber, polyacrylonitrile, polymethyl acrylate, polymethyl methacrylate, polyvinyl chloride, polyfluoride Examples thereof include vinylidene and epoxy resin, and examples thereof include a copolymer or a mixture thereof.

(Disperser / Mixer)
As an apparatus used when obtaining the conductive composition of the present invention or a composite ink described later, a disperser or a mixer that is usually used for pigment dispersion or the like can be used.

  For example, mixers such as dispersers, homomixers, or planetary mixers; homogenizers such as “Clearmix” manufactured by M Technique, or “fillmix” manufactured by PRIMIX; paint conditioner (manufactured by Red Devil), ball mill, sand mill (Shinmaru Enterprises "Dynomill", etc.), Attritor, Pearl Mill (Eirich "DCP Mill", etc.), or Coball Mill, etc .; Media type dispersers; Wet Jet Mill (Genus, "Genus PY", Sugino Media-less dispersers such as “Starburst” manufactured by Machine, “Nanomizer” manufactured by Nanomizer, etc., “Claire SS-5” manufactured by M Technique, or “MICROS” manufactured by Nara Machinery; or other roll mills, etc. Although The present invention is not limited to these. Moreover, as the disperser, it is preferable to use a disperser that has been subjected to a metal contamination prevention treatment from the disperser.

  For example, when using a media-type disperser, a disperser in which the agitator and vessel are made of a ceramic or resin disperser, or the surface of the metal agitator and vessel is treated with tungsten carbide spraying or resin coating. Is preferably used. As the media, it is preferable to use glass beads, ceramic beads such as zirconia beads or alumina beads. Moreover, 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. Further, in the case of a positive or negative electrode active material in which particles are easily broken or crushed by a strong impact, a medialess disperser such as a roll mill or a homogenizer is preferable to a media type disperser.

(Current collector with base layer for electricity storage device, electrode for electricity storage device)
The current collector with an underlayer for an electricity storage device of the present invention has an underlayer formed from the conductive composition of the present invention on the current collector.

  The electrode for an electricity storage device of the present invention is an electrode-forming composition (composite material) comprising an underlayer formed from the conductive composition of the present invention on a current collector, an electrode active material, and a binder. And a composite material layer formed from the ink).

(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 for the current collector include metals and alloys such as aluminum, copper, nickel, titanium, and stainless steel. In the case of a lithium ion battery, aluminum is particularly preferable as the positive electrode material, and copper is preferable as the negative electrode material.

  In general, a flat foil is used as the shape, but a roughened surface, a perforated foil, or a mesh current collector can also be used.

  There is no restriction | limiting in particular as a method of apply | coating a conductive composition and the mixture ink mentioned later on a collector, A well-known method can be used.

  Specific examples 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 the like. Examples of methods that can be used include standing drying, blower dryers, hot air dryers, infrared heaters, and far-infrared heaters, but are not particularly limited thereto.

Moreover, you may perform the rolling process by a lithographic press, a calender roll, etc. after application | coating. The thickness of the underlayer is generally from 0.1 μm to 5 μm, preferably from 0.1 μm to 2 μm. 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.
<Composite ink>
As described above, a general ink mixture for a power storage device essentially includes an active material and a solvent, and contains a conductive additive and a binder as necessary.

  The active material is preferably contained as much as possible. For example, the proportion of the active material in the solid material solid content is preferably 80% by weight or more and 99% by weight or less. When the conductive assistant is included, the proportion of the conductive assistant in the solid ink solid content is preferably 0.1 to 15% by weight. When the binder is included, the ratio of the binder to the solid material ink solid content is preferably 0.1 to 15% by weight.

  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 30 to 90% by weight of the solid content.

(Active material)
The active material used in the composite ink will be described below.

  The positive electrode active material for the lithium ion secondary battery is not particularly limited, but metal oxides capable of doping or intercalating lithium ions, metal compounds such as metal sulfides, and conductive polymers are used. be able to.

Examples thereof include transition metal oxides such as Fe, Co, Ni, and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , layered structure lithium nickelate, lithium cobaltate, lithium manganate, spinel structure lithium manganate, etc. Examples thereof include composite oxide powders of lithium and transition metals, lithium iron phosphate materials that are phosphate compounds having an olivine structure, and transition metal sulfide powders such as TiS ₂ and FeS.

  In addition, conductive polymers such as polyaniline, polyacetylene, polypyrrole, and polythiophene can also be used. Moreover, you may mix and use said inorganic compound and organic compound.

The negative electrode active material for the lithium ion secondary battery is not particularly limited as long as it can be doped or intercalated with lithium ions. For example, metal Li, alloys thereof such as tin alloys, silicon alloys, lead alloys, Li _x Fe ₂ O ₃ , Li _x Fe ₃ O ₄ , Li _x WO ₂ , lithium titanate, lithium vanadate, silicon Metal oxides such as lithium oxide, conductive polymers such as polyacetylene and poly-p-phenylene, amorphous carbonaceous materials such as soft carbon and hard carbon, artificial graphite such as highly graphitized carbon materials, or natural Examples thereof include carbonaceous powders such as graphite, carbon black, mesophase carbon black, resin-fired carbon materials, air-growth carbon fibers, and carbon fibers. These negative electrode active materials can be used alone or in combination.

  The size of these electrode active materials is preferably in the range of 0.05 to 100 μm, and more preferably in the range of 0.1 to 50 μm. And it is preferable that the dispersed particle diameter of the electrode active material (A) in compound-material ink is 0.5-20 micrometers. The dispersed particle size referred to here is a particle size (D50) that is 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution. A particle size distribution meter such as a dynamic light scattering type particle size distribution meter ("Microtrack UPA" manufactured by Nikkiso Co., Ltd.).

Although it does not specifically limit as an electrode active material for electric double layer capacitors, Activated carbon, polyacene, carbon whisker, graphite, etc. are mentioned, These powder or fiber etc. are mentioned. The preferred electrode active material for the electric double layer capacitor is activated carbon, specifically activated carbon activated with phenolic, coconut shell, rayon, acrylic, coal / petroleum pitch coke, mesocarbon microbeads (MCMB), etc. Can be mentioned. Those having a large specific surface area capable of forming an interface having a larger area even with the same weight are preferred. Specifically, the specific surface area is 30 m ² / g or more, preferably 500 to 5000 m ² / g, more preferably 1000 to 3000 m ² / g.
These electrode active materials can be used alone or in combination of two or more kinds, or two or more kinds of carbons having different average particle diameters or particle size distributions may be used in combination.

  The positive electrode active material for the lithium ion capacitor is not particularly limited as long as it is a material capable of reversibly doping and dedoping lithium ions and anions, and examples thereof include activated carbon powder. The dispersed particle size of the activated carbon is preferably 0.1 μm to 20 μm. The dispersed particle diameter here is as described above.

  The negative electrode active material for the lithium ion capacitor is not particularly limited as long as it is a material capable of reversibly doping and dedoping lithium ions. For example, graphite-based materials such as artificial graphite and natural graphite can be used. Can be mentioned. The dispersed particle size of the activated carbon is preferably 0.1 μm to 20 μm. The dispersed particle diameter here is as described above.

  The conductive assistant in the composite ink is not particularly limited as long as it is a carbon material having conductivity, and the same conductive carbon material (A) as described above can be used.

  The binder in the composite ink is used for binding particles such as an active material or a conductive carbon material, or a conductive carbon material and a current collector.

Examples of binders used in the composite ink include acrylic resin, polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicon resin, fluorine resin, Cellulose resins such as carboxymethylcellulose, synthetic rubbers such as styrene-butadiene rubber and fluororubber, conductive resins such as polyaniline and polyacetylene, polymer compounds containing fluorine atoms such as polyvinylidene fluoride, polyvinyl fluoride, and tetrafluoroethylene Is mentioned. Further, a modified product, a mixture, or a copolymer of these resins may be used. These binders can be used alone or in combination.
The binder suitably used in the water-based composite ink is preferably an aqueous medium, and examples of the aqueous medium binder include water-soluble type, emulsion type, hydrosol type, and the like. be able to.

Furthermore, a film forming aid, an antifoaming agent, a leveling agent, a preservative, a pH adjuster, a viscosity adjuster, and the like can be blended in the composite ink as necessary.
<Method for producing electrode>
The conductive composition of the present invention can be applied and dried on a current collector to form a base layer, whereby a base layer electrode for an electricity storage device can be obtained.

  Alternatively, the conductive composition of the present invention can be applied to a current collector and dried to form a base layer, and a composite layer can be provided on the base layer to obtain an electrode for an electricity storage device. The composite material layer provided on the base layer can be formed using the above-described composite ink.

<Power storage device>
By using the above electrode for at least one of the positive electrode and the negative electrode, an electricity storage device such as a secondary battery or a capacitor can be obtained.

Secondary batteries include lithium ion secondary batteries, sodium ion secondary batteries, magnesium ion secondary batteries, alkaline secondary batteries, lead storage batteries, sodium sulfur secondary batteries, lithium air secondary batteries, etc. An electrolyte solution, a separator, and the like that are conventionally known for each secondary battery can be appropriately used.
Examples of the capacitor include an electric double layer capacitor, a lithium ion capacitor, and the like, and an electrolyte, a separator, and the like that are conventionally known for each capacitor can be appropriately used.

(Electrolyte)
A case of a lithium ion secondary battery will be described as an example. As the electrolytic solution, an electrolyte containing lithium dissolved in a non-aqueous solvent is used.

As the _{electrolyte, 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,
Examples include, but are not limited to, LiI, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN, or LiBPh ₄ .

The non-aqueous solvent is not particularly limited.
Carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl 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
Nitriles such as acetonitrile are exemplified. These solvents may be used alone or in combination of two or more.

Furthermore, the electrolyte solution may be a polymer electrolyte that is held in a polymer matrix and made into a gel. 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, but are not limited to, a polyethylene nonwoven fabric, a polypropylene nonwoven fabric, a polyamide nonwoven fabric and those obtained by subjecting them to a hydrophilic treatment.
(Battery structure / configuration)
The structure of the lithium ion secondary battery, the electric double layer capacitor, and the lithium ion capacitor using the composition of the present invention is not particularly limited, and is usually composed of a positive electrode and a negative electrode, and a separator provided as necessary. Various shapes can be formed according to the purpose of use, such as a paper type, a cylindrical type, a button type, and a laminated type.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. In the examples and comparative examples, “part” represents “part by weight”.

<Preparation of aqueous dispersion of resin fine particles>
[Synthesis Example 1]
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 Soap SR-10 (manufactured by ADEKA) as a surfactant. 48.5 parts of methyl 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 rear soap SR-10 (ADEKA Corporation as a surfactant) 1% of the pre-emulsion that had previously been mixed with 1.8 parts was added. After raising the internal temperature to 70 ° C. and sufficiently substituting 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 dropped over 3 hours while maintaining the internal temperature at 70 ° C., and stirring was further continued for 2 hours. . After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. 25% aqueous ammonia was added to adjust the pH to 8.5, and the solid content was adjusted to 40% with ion exchange water to obtain a resin fine particle water dispersion. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

<Production of Compound (E) [Production of Epoxy Group-Containing Compound]>
[Production Example 1]
Into a reaction vessel equipped with a stirrer, thermometer, dropping funnel and refluxing vessel, 20 parts of isopropyl alcohol and 20 parts of water were charged, and 40 parts of methyl methacrylate, 40 parts of methyl acrylate and 20 parts of glycidyl methacrylate were separately added to the dropping tank 1, Moreover, 2 parts of potassium persulfate was dissolved in 30 parts of isopropyl alcohol and 30 parts of water, and charged into the dropping tank 2. After the internal temperature was raised to 80 ° C. and sufficiently substituted with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours to carry out polymerization. After completion of the dropwise addition, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. and an epoxy having a solid content of 40%. A group-containing compound (methyl methacrylate / methyl acrylate / glycidyl methacrylate copolymer) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

<Production of Compound (E) [Production of Amide Group-Containing Compound]>
[Production Example 2]
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a refluxing vessel was charged with 90 parts of water. Separately, 20 parts of acrylamide was dissolved in the dropping tank 1 and 2 parts of potassium persulfate was dissolved in 90 parts of water. The dropping tank 2 was charged. After the internal temperature was raised to 80 ° C. and sufficiently substituted with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours to carry out polymerization. After completion of the dropping, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C., and the amide having a solid content of 40% was obtained. A group-containing compound (polyacrylamide) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

[Production Example 3]
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a refluxing vessel was charged with 40 parts of water. Separately, 40 parts of 2-ethylhexyl acrylate, 40 parts of styrene, and 20 parts of dimethylacrylamide were added to the dropping tank 1, and 2 parts of potassium sulfate was dissolved in 60 parts of water and charged into the dropping tank 2. After the internal temperature was raised to 80 ° C. and sufficiently substituted with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours to carry out polymerization. After completion of the dropping, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C., and the amide having a solid content of 40% was obtained. A group-containing compound (2-ethylhexyl acrylate / styrene / dimethylacrylamide copolymer) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

<Production of Compound (E) [Production of Hydroxyl-Containing Compound]>
[Production Example 4]
Into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a refluxing vessel, 20 parts of isopropyl alcohol and 20 parts of water are charged, and 40 parts of methyl methacrylate, 40 parts of butyl acrylate, and 20 parts of 2-hydroxyethyl methacrylate are separately added dropwise. In the tank 1, 2 parts of potassium persulfate was dissolved in 30 parts of isopropyl alcohol and 30 parts of water and charged into the dropping tank 2. After the internal temperature was raised to 80 ° C. and sufficiently substituted with nitrogen, the dropping tanks 1 and 2 were dropped over 2 hours to carry out polymerization. After completion of the dropping, stirring was continued for 1 hour while maintaining the internal temperature at 80 ° C. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C., and the hydroxyl group having a solid content of 40% A containing compound (methyl methacrylate / butyl acrylate / 2-hydroxyethyl methacrylate copolymer) solution was obtained. In addition, solid content was calculated | required by 150 degreeC 20 minute baking residue.

[Synthesis Examples 2 to 21]
The compounding compositions shown in Table 5, Table 6, and Table 11 were synthesized in the same manner as in Synthesis Example 1 to obtain resin fine particle aqueous dispersions of Synthesis Examples 2 to 21. However, in Synthesis Examples 20 and 21, the resin aggregated during emulsion polymerization, and the desired resin fine particles could not be obtained.

<Conductive composition>
Example 1
Acetylene black (A-1: Denka Black HS-100) as a conductive carbon material
10 parts, 50 parts of polyallylamine 20% aqueous solution (B-1) as a water-soluble resin binder (10 parts as a solid content), polytetrafluoroethylene 30-J (Mitsui / Dupont Fluoro) as a water-dispersible resin fine particle binder (Made by Chemical Co., Ltd.) 16.7 parts (10 parts as solid content) of 60% aqueous dispersion (C-1) and 223.3 parts of water are mixed in a mixer, and further dispersed in a sand mill to conduct conductivity. Sex composition (1) was obtained. The degree of dispersion of the obtained dispersion was determined by determination with a grind gauge (in accordance with JISK5600-2-5). The evaluation results are shown in Table 1. The numbers in the table indicate the size of the coarse particles, and the smaller the value, the better the dispersibility, and the more uniform and good state.

(Example 2 to Example 6, Example 23, Example 24, Comparative Example 1 to Comparative Example 6)
Conductive compositions (2) to (14) of Examples and Comparative Examples were obtained at the composition ratio shown in Table 1 by the same method as that for the conductive composition (1).

  And after apply | coating this electrically conductive composition (1) on the 20-micrometer-thick aluminum foil used as a collector using a bar coater, it heat-drys and it is for electrical storage devices so that thickness may be set to 1.2 micrometers. A current collector (1) with an underlayer was obtained. The solvent resistance of the obtained collector with an underlayer was evaluated by the following method.

Moreover, current collectors with underlayers for power storage devices (2) to (28) were obtained by the same method as the current collector with base layers for power storage devices (1) with the configuration shown in Table 2, and the same evaluations were made. went.
(Solvent resistance of current collector with base layer)
The surface of the current collector with the underlayer produced above was rubbed with a cotton cloth containing NMP (N-methylpyrrolidone) to evaluate the solvent resistance. When the composite ink is applied onto the underlayer, solvent resistance is important so that the underlayer does not collapse. The evaluation criteria are shown below, and the evaluation results are shown in Table 2.

○: “No shaving is seen (a level where there is no practical problem)”
○ △: “The foundation layer is slightly scraped and attached to the cotton cloth, but the surface of the current collector is not exposed (although there is a problem, it can be used)”
Δ: “Underlayer is shaved and the current collector surface is partially exposed”
×: “Underly layer is completely scraped off”

<Composite ink for lithium ion secondary battery positive electrode>
As a positive electrode active material, 44 parts of LiFePO _{4, 3} parts of a conductive additive (acetylene black), 3 parts of a binder (PVDF), and 50 parts of NMP (N-methylpyrrolidone) were mixed to prepare a positive electrode mixture ink.
<Composite ink for negative electrode for lithium ion secondary battery>
As a negative electrode active material, 46.5 parts of artificial graphite, 1 part of a conductive additive (acetylene black), 2.5 parts of binder (PVDF), and 50 parts of NMP were mixed to prepare a mixture ink for negative electrode.
<Positive electrode for lithium ion secondary battery without base layer (comparative example and counter electrode for evaluation)>
After applying the above-mentioned ink mixture for a lithium ion secondary battery positive electrode onto a 20 μm thick aluminum foil serving as a current collector using a doctor blade, drying under reduced pressure is performed to adjust the electrode thickness to 100 μm. did. Furthermore, the rolling process by roll press was performed and the positive electrode from which thickness becomes 85 micrometers was produced.

<Positive electrode for lithium ion secondary battery with underlayer>
[Example 11]
The above-mentioned ink mixture for lithium ion secondary battery positive electrode is applied on the current collector (1) with a base layer for secondary battery using a doctor blade, and then dried by heating under reduced pressure to give an electrode thickness of 100 μm. Adjusted as follows. Furthermore, the rolling process by roll press was performed and the positive electrode from which thickness becomes 85 micrometers was produced. The adhesion of the obtained electrode was evaluated by the following method. The evaluation results are shown in Table 3.
[Examples 12-16, 25, 26, Comparative Examples 11-17]
A positive electrode was obtained in the same manner as in Example 11 except that the base electrode for the electricity storage device shown in Table 2 was used, and the same evaluation as in Example 11 was performed. The evaluation results are shown in Table 3.

<Negative Electrode for Lithium Ion Secondary Batteries (Comparative Example and Evaluation Counter Electrode)>
After applying the above-mentioned ink mixture for lithium ion secondary battery negative electrode on a 20 μm thick copper foil as a current collector using a doctor blade, drying under reduced pressure is performed to adjust the electrode thickness to 82 μm. did. Furthermore, the rolling process by a roll press was performed and the negative electrode from which thickness becomes 70 micrometers was produced.

<Anode for lithium ion secondary battery with underlayer>
[Example 17]
After applying the above-mentioned ink mixture for lithium ion secondary battery negative electrode on the current collector (7) with a base layer for an electricity storage device using a doctor blade, drying under reduced pressure is performed so that the thickness of the electrode becomes 82 μm. It was adjusted. A rolling process using a roll press was performed to produce a negative electrode having a thickness of 70 μm. The adhesion of the obtained electrode was evaluated by the following method. The evaluation results are shown in Table 4.
[Examples 18-22, 27, 28, Comparative Examples 18-24]
A negative electrode was obtained in the same manner as in Example 17 except that the current collector with a base layer for an electricity storage device shown in Table 4 was used. Evaluation similar to Example 17 was performed and the evaluation results are shown in Table 4.

(Electrode adhesion)
Using the knife, the incision from the surface of the electrode to the depth reaching the current collector was cut into 6 grids in the vertical and horizontal directions at intervals of 2 mm. Adhesive tape was applied to the cut and immediately peeled off, and the degree of electrode dropping was determined by visual judgment.
The evaluation criteria are shown below.

○: “No peeling (practical level)”
○ △: “Slightly peeled (problem but usable level)”
Δ: “About half peel”
×: “Peeling at most parts”

<Coin-type lithium ion secondary battery>
The positive electrode and negative electrode shown in Tables 3 and 4 were each punched out to a diameter of 16 mm, and a separator (porous polypropylene film) inserted between them and an electrolytic solution (ethylene carbonate and diethyl carbonate at a ratio of 1: 1 (volume ratio)) A coin-type battery comprising a non-aqueous electrolyte solution in which LiPF ₆ was dissolved in a mixed solvent at a concentration of 1M was prepared. The coin-type battery was used in a glove box substituted with argon gas, and a predetermined battery characteristic evaluation was performed after the coin-type battery was produced. The evaluation results are shown in Tables 3 and 4.
(Charge / discharge cycle characteristics)
About the obtained coin-type battery, charging / discharging measurement was performed using the charging / discharging apparatus (SM-8 by Hokuto Denko).

  After performing a constant current and constant voltage charge (cutoff current 0.1 mA) at a charge end voltage of 4.0 V at a charge current of 1.0 mA (0.2 C), the discharge end voltage is 2.0 V at a discharge current of 1.0 mA. The constant current discharge was performed until it reached. These charge / discharge cycles are defined as one cycle, and 5 cycles of charge / discharge are repeated, and the discharge capacity at the fifth cycle is defined as the initial discharge capacity. (The initial discharge capacity is assumed to be 100% maintenance rate).

  Next, after performing constant current and constant voltage charging (cutoff current 0.5 mA) at a charging current 5.0 mA at a charging current 5.0 mA in a 50 ° C. constant temperature bath, a discharge final voltage is discharged at a discharge current 5.0 mA. Constant current discharge was performed until 2.0V was reached. This charge / discharge cycle was performed 200 times, and the change rate of the discharge capacity maintenance rate (percentage of the 200th discharge capacity with respect to the initial discharge capacity) was calculated (the closer to 100%, the better).

○: “Change rate is 90% or more. Particularly excellent.”
○ △: “Change rate is 85% or more and less than 90%. No problem at all”
Δ: “Change rate is 80% or more and less than 85%.
X: “Change rate is less than 80%.

<Positive electrode for electric double layer capacitor, mixed ink for negative electrode>
Active material (specific surface area 1800m ² / g) 88 parts, conductive additive (acetylene black) 5 parts, binder (PVDF) 7 parts, NMP (N-methylpyrrolidone) 230 parts are mixed as an active material, for positive electrode and negative electrode A composite ink was prepared.
<Positive electrode and negative electrode for an electric double layer capacitor without a base layer (comparative example and counter electrode for evaluation)>
After applying the above-mentioned ink mixture for electric double layer capacitor on a 20 μm thick aluminum foil serving as a current collector using a doctor blade, it was dried by heating under reduced pressure, and then subjected to a rolling process by a roll press to obtain the thickness of the electrode. A positive electrode and a negative electrode having a thickness of 50 μm were prepared.

<Positive electrode and negative electrode for electric double layer capacitor with underlying layer>
[Example 29]
After applying the above-mentioned ink mixture for electric double layer on the collector (1) with an underlayer for electricity storage device using a doctor blade, after drying by heating under reduced pressure, a rolling process is performed by a roll press, and the thickness is reduced. A positive electrode and a negative electrode with a thickness of 50 μm were prepared. The adhesion of the obtained electrode was evaluated by the method described above. Table 7 shows the evaluation results.
[Examples 30 to 44, Comparative Examples 25 to 38]
A positive electrode and a negative electrode were obtained in the same manner as in Example 29 except that the base electrode for the electricity storage device shown in Tables 7 and 8 was used. The evaluation results are shown in Tables 7 and 8.

<Electric double layer capacitor>
The positive electrode and the negative electrode shown in Tables 7 and 8 are each punched out to a diameter of 16 mm, and a separator (porous polypropylene film) inserted between them and an electrolytic solution (TEMABF ₄ (triethylmethylammonium tetrafluoride) in a propylene carbonate solvent) An electric double layer capacitor was prepared in a glove box substituted with argon gas, and after the electric double layer capacitor was prepared, a predetermined electric capacity was obtained. The evaluation results are shown in Tables 7 and 8.

(Charge / discharge cycle characteristics)
About the obtained electric double layer capacitor, charging / discharging measurement was performed using the charging / discharging apparatus.

  After charging to a charge end voltage of 2.0 V at a charge current of 10 C, constant current discharge was performed until the discharge end voltage of 0 V was reached at a discharge current of 10 C. These charge / discharge cycles are defined as one cycle, and 5 cycles of charge / discharge are repeated, and the discharge capacity at the fifth cycle is defined as the initial discharge capacity. (The initial discharge capacity is assumed to be 100% maintenance rate). In addition, the charge / discharge current rate was 1 C, which is the magnitude of current that can discharge the cell capacity in one hour.

  Next, charging was performed at a charging current 10C rate in a 50 ° C. constant temperature bath at a charging end voltage of 2.0 V, and then constant current discharging was performed at a discharging current of 10 C rate until reaching a discharging end voltage of 0 V. This charge / discharge cycle was performed 500 times, and the change rate of the discharge capacity maintenance rate (percentage of the 500th discharge capacity with respect to the initial discharge capacity) was calculated (the closer to 100%, the better).

○: “Change rate is 95% or more. Particularly excellent.”
○: “Change rate is 90% or more and less than 85%. No problem at all”
Δ: “Change rate is 85% or more and less than 80%.
×: “Change rate is less than 85%.

<Composite ink for positive electrode for lithium ion capacitor>
Active material (specific surface area 1800m ² / g) 88 parts, conductive auxiliary agent (acetylene black) 5 parts, binder (PVDF) 7 parts, NMP (N-methylpyrrolidone) 230 parts are mixed as an active material. An ink was prepared.
<Composite ink for negative electrode for lithium ion capacitor>
As a negative electrode active material, 90 parts of graphite, 5 parts of a conductive additive (acetylene black), 5 parts of a binder (PVDF), and 200 parts of NMP were mixed to prepare a mixture ink for negative electrode.
<Positive electrode for lithium ion capacitor without base layer (comparative example and counter electrode for evaluation)>
After applying the above-mentioned ink mixture for the positive electrode for lithium ion capacitors onto a 20 μm thick aluminum foil serving as a current collector using a doctor blade, after heating and drying under reduced pressure and performing a rolling process by a roll press, A positive electrode having a thickness of 60 μm was produced.

<Positive electrode for lithium ion capacitor with underlayer>
[Example 45]
After applying the above-mentioned ink mixture for positive electrode for lithium ion capacitor on the current collector (1) with an underlayer for electricity storage device using a doctor blade, after drying by heating under reduced pressure and rolling by roll press A positive electrode having a thickness of 60 μm was prepared. The adhesion of the obtained electrode was evaluated by the method described above. Table 9 shows the evaluation results.
[Examples 46 to 52, Comparative Examples 39 to 45]
A positive electrode was obtained in the same manner as in Example 45 except that the current collector with a base layer for an electricity storage device shown in Table 9 was used. Table 9 shows the evaluation results.

<Negative Electrode for Lithium Ion Capacitor (Comparative Example and Counter Electrode for Evaluation)>
After applying the above-mentioned ink mixture for the negative electrode for lithium ion capacitors on a copper foil having a thickness of 20 μm to be a current collector, using a doctor blade, drying under reduced pressure and performing a rolling process by a roll press, A negative electrode having a thickness of 45 μm was produced.

<Anode for Lithium Ion Capacitor with Underlayer>
[Example 53]
After applying the above-mentioned ink mixture for negative electrode for lithium ion capacitor on the current collector with an underlayer for power storage device (7) using a doctor blade, after drying by heating under reduced pressure and rolling by roll press A negative electrode having a thickness of 45 μm was prepared. The adhesion of the obtained electrode was evaluated by the method described above. Table 10 shows the evaluation results.
[Examples 54 to 60, Comparative Examples 46 to 52]
A negative electrode was obtained in the same manner as in Example 53 except that the current collector with a base layer for an electricity storage device shown in Table 10 was used. Table 10 shows the evaluation results.

<Lithium ion capacitor>
A positive electrode shown in Tables 9 and 10 and a negative electrode previously half-doped with lithium ions were prepared with a diameter of 16 mm, a separator (porous polypropylene film) inserted between them, and an electrolyte (ethylene) A lithium ion capacitor comprising a non-aqueous electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent in which carbonate, dimethyl carbonate and diethyl carbonate were mixed at a ratio of 1: 1: 1 (volume ratio) was produced. Lithium ion half dope was performed by sandwiching a separator between the negative electrode and lithium metal in a beaker cell, and doping the negative electrode with lithium ions so that the amount was about half of the negative electrode capacity. Moreover, the lithium ion capacitor was performed in a glove box substituted with argon gas, and a predetermined electrical property evaluation was performed after the lithium ion capacitor was fabricated. The evaluation results are shown in Tables 9 and 10.

(Charge / discharge cycle characteristics)
About the obtained lithium ion capacitor, charging / discharging measurement was performed using the charging / discharging apparatus.

  After charging to a charge end voltage of 4.0 V at a charge current of 10 C, constant current discharge was performed until the discharge end voltage of 2.0 V was reached at a discharge current of 10 C. These charge / discharge cycles are defined as one cycle, and 5 cycles of charge / discharge are repeated, and the discharge capacity at the fifth cycle is defined as the initial discharge capacity. (The initial discharge capacity is assumed to be 100% maintenance rate).

  Next, after charging at a charging end voltage of 4.0 V at a charging current of 10 C in a constant temperature bath at 50 ° C., constant current discharging was performed until the discharging end voltage of 2.0 V was reached at a discharge current of 10 C. This charge / discharge cycle was performed 500 times, and the change rate of the discharge capacity maintenance rate (percentage of the 500th discharge capacity with respect to the initial discharge capacity) was calculated (the closer to 100%, the better).

○: “Change rate is 95% or more. Particularly excellent.”
○ △: “Change rate is 90% or more and less than 95%. No problem at all”
Δ: “Change rate is 85% or more and less than 90%.
×: “Change rate is less than 85%.

  As shown in Tables 3, 4, and 7 to 10, when an underlayer formed from the conductive composition of the present invention was used, a mixture ink was applied onto the underlayer to produce a positive electrode or a negative electrode. In this case, the adhesion of the electrode could be greatly improved without causing any trouble. Furthermore, since the conductive composition of the present invention has good dispersibility of the conductive carbon material, the balance of electrode physical properties is improved, and it is considered that the charge / discharge cycle characteristics are improved in battery and capacitor characteristics. In particular, when the ratio of the total mass of the water-soluble resin binder (B) and the water-dispersible resin fine particle binder (C) is within a specific range of the present invention, the dispersion state of the material, adhesion, conductivity, etc. It was found that a good balance of electrode physical properties was exhibited, and further good battery and capacitor characteristics could be obtained. Batteries and capacitors may be used at high temperatures where the environment in which they are used is severe, and durability is important, so it is considered that the balance of electrode properties is very important.

  If the electrode adhesion is insufficient, it is difficult to maintain the long-term durability of the battery or capacitor, which causes deterioration. When the dispersion control of the conductive carbon material is insufficient as in Comparative Example 1, there is a tendency that the adhesion of the electrode is insufficient, and the deterioration is noticeable. When dispersion control of conductive carbon material is insufficient, a uniform conductive network as an electrode is not formed, resulting in a resistance distribution due to partial aggregation in the electrode, which can be used as a battery or capacitor. It is considered that the current concentration at the time of occurrence may cause deterioration promotion.

In addition, as shown in Tables 3 and 4, in the case of the underlayer formed from the conductive composition of the present invention, it should be better than the evaluation result of Comparative Example 11 in which the underlayer is not used. I understand. Moreover, in the comparative example 12, when the conductive composition of a comparative example is used for a base layer, it turns out that a favorable physical property is not acquired. This is considered because the contact state between the current collector and the composite layer was in an insufficient state, and thus became a non-uniform state as an electrode than when not using the underlayer, This is thought to be a result that supports the balance of electrode physical properties.

Claims (5)

A conductive composition containing a conductive carbon material (A), a water-soluble resin binder (B), a water-dispersible resin fine particle binder (C), and an aqueous liquid medium (D),
The total content of the conductive carbon material (A), water-soluble resin binder (B) and water-dispersible resin fine particle binder (C) is 100% by weight, and the content of the conductive carbon material (A) is 20%. ~ 70% by weight,
The content of the water-soluble resin binder (B) is 40 to 95% by weight in the total solid content of 100% by weight of the water-soluble resin binder (B) and the water-dispersible resin fine particle binder (C). Conductive composition.   The conductive composition according to claim 1, wherein the conductive composition is used for forming a base layer of an electrode for an electricity storage device.   A current collector with an underlayer for an electricity storage device, comprising: a current collector; and an underlayer formed from the conductive composition according to claim 1.   An electricity storage device comprising: a current collector; an underlayer formed from the conductive composition according to claim 1; and a composite material layer formed from an electrode-forming composition containing an electrode active material and a binder. Electrode.   The electrical storage device which comprises a positive electrode, a negative electrode, and electrolyte solution, Comprising: At least one of the said positive electrode or the said negative electrode is an electrode for electrical storage devices of Claim 4.