JP2019003781A - Binder for electrode - Google Patents

Abstract

To provide a binder for an electrode, which is satisfactory in bindability to various substances for forming an electrode, and even in a small amount, has a high binding force.SOLUTION: A binder for an electrode comprises: copolymer latex particles having (a) a monomer unit originating from an ethylenic unsaturated carboxylic acid ester compound, (b) a monomer unit originating from an ethylenic unsaturated sulfonic acid compound and (c) a monomer unit originating from an ethylenic unsaturated carboxylic acid compound; and an aqueous solvent in which the copolymer latex particles are dispersed. The mass proportion of the component (a) and the component (c) is in a range of 99.9:0.1 to 99.0:1.0. The solid content in the aqueous solvent is in a range of 0.2-70 mass%. The copolymer latex particles has a median diameter in a range of 50 nm or more and 200 nm or less.SELECTED DRAWING: None

Description

  The present invention relates to an electrode binder, an electrode material slurry using the electrode binder, an electrode using the same, a secondary battery, and an electric double layer capacitor.

  In recent years, in electronic devices, secondary batteries such as lithium ion secondary batteries, nickel hydride secondary batteries, nickel cadmium secondary batteries and capacitors such as electric double layer capacitors that can be repeatedly used by charging have been used. .

  These secondary batteries and capacitors are generally configured to include an electrode, a separator, and an electrolytic solution containing an electrolyte. An electrode is manufactured by coating and drying an electrode material slurry, in which an electrode active material is dispersed in a solvent in which a binder (binder) is dissolved, on an electrode current collector to form a mixture layer.

  Conventionally, polyvinylidene fluoride (hereinafter referred to as PVDF) has been used industrially as a binder for lithium ion secondary battery electrodes, but it has not been able to adequately meet recent demand levels for battery performance enhancement. .

  When PVDF is used as a binder, for example, as disclosed in Patent Document 1 and the like, amides such as N-methylpyrrolidone (hereinafter referred to as NMP) are used as a solvent for laminating a mixture layer. Nitrogen-containing organic solvents such as ureas are used. However, nitrogen-containing organic solvents such as NMP must be recovered because the solvent vapor generated during drying becomes an environmental problem if released to the atmosphere as it is.

  Thus, it has been proposed to use an aqueous binder as the binder. For example, Patent Document 2 discloses a paste obtained by using a mixed hydrate of an acrylic copolymer aqueous emulsion and carboxymethyl cellulose as a negative electrode active material as a negative electrode active material and dispersing them in water as a solvent. A negative electrode composite is shown.

  However, conventional aqueous binders are mainly diverted to the negative electrode plate, and are insufficient for diverting to the positive electrode plate, particularly the dispersion of the coating slurry in the electrode plate manufacturing process, and the resulting battery performance is not sufficient. There was a problem such as.

  In particular, the viscosity aging stability of the mixture slurry and the binding property with the current collector affect the battery cycle characteristics, and hence improvement is required. When PVDF is used as a binder, there are problems such as insufficient binding force between the current collector and the electrode film and between the active materials, and there is a problem in cycle characteristics due to peeling and dropping of the mixture.

  To solve these problems, the binder and coating stability are improved by using an aqueous binder. For example, Patent Document 3 shows that by using a carboxy-modified styrene / butadiene emulsion having a number average particle size of 50 to 300 nm as a polymer binder, a slurry suitable for binding properties and coating suitability can be obtained. Yes.

  Moreover, in patent document 4, by using the binder which mixed the binder emulsion (I) with a particle diameter of 0.01 micrometer-0.25 micrometer and the binder emulsion (II) of 0.25 micrometer-3 micrometers, It has been shown that the capacity of the battery is increased and the rate characteristics are improved by improving the binding property with the current collector and reducing the amount of binder in the mixture.

  Patent Document 5 proposes an electrode binder including polymer particles containing an ethylenically unsaturated carboxylic acid ester compound and an ethylenically unsaturated sulfonic acid compound in a specific ratio. The thing with the smoothness of the coating film when applied to an electric body is disclosed.

JP 2004-134365 A JP 2000-294230 A JP 2010-192434 A Japanese Patent Laid-Open No. 2003-1000029 International Publication No. 2013/069558

  However, the improvements described in the above-mentioned patent documents do not meet the recent demand for higher performance of batteries. With the progress of development of active materials in the technical field, binders are also required to have higher performance than the prior art. In addition, from the viewpoint of increasing the capacity and resistance of a battery, it is also required to exhibit a high function while reducing the amount of binder added.

  In view of the above problems, the present inventors have found that if the median diameter of the copolymer latex particles contained in the binder is within a specific range, it can contribute to the formation of an electrode with good properties, and the present invention is completed. It came.

  That is, the embodiment of the present invention provides the following.

[1]
(A) a monomer unit derived from an ethylenically unsaturated carboxylic acid ester compound;
(B) a monomer unit derived from an ethylenically unsaturated sulfonic acid compound;
(C) including copolymer latex particles having monomer units derived from an ethylenically unsaturated carboxylic acid compound as a form dispersed in an aqueous solvent,
The mass ratio of the component (a) and the component (c) is in the range of 99.9: 0.1 to 99.0: 1.0,
The solid content in the aqueous solvent is in the range of 0.2 to 70% by mass,
The binder for an electrode, wherein a median diameter of the copolymer latex particles is in a range of 50 nm to 200 nm.

[2]
The binder for electrodes as described in [1] whose content of (c) component is 0.1-1.0 mass% with respect to the total amount of (a) component, (b) component, and (c) component. .

[3]
The electrode according to [1] or [2], wherein the content of the component (b) is 0.03 to 3% by mass with respect to the total amount of the component (a), the component (b), and the component (c). Binder.

[4]
The electrode material slurry containing the binder for electrodes of any one of [1] to [3], a conductive support agent, and an active material.

[5]
The electrode material slurry according to [4], wherein the content of the electrode binder is 0.1 to 10 parts by mass with respect to 100 parts by mass of the active material as a solid content.

[6]
The electrode containing the application | coating drying layer of the electrode material slurry as described in [4] or [5].

[7]
A secondary battery comprising the electrode according to [6].

[8]
An electric double layer capacitor comprising the electrode according to [6].

[9]
The mass ratio (a) :( c) = 99.9: (a) ethylenically unsaturated carboxylic acid ester compound, (b) ethylenically unsaturated sulfonic acid compound and (c) ethylenically unsaturated carboxylic acid compound. Preparing to be in the range of 0.1 to 99.0: 1.0;
Adding 1 to 15% by mass of the total amount of the component (a), the component (b) and the component (c) in the aqueous solvent, and performing initial polymerization;
Copolymer latex particles having a median diameter in the range of 50 nm or more and 200 nm or less by adding the remaining amount of component (a), component (b) and component (c) to the initially polymerized system. Preparing a step;
And a step of dispersing the copolymer latex particles in the aqueous solvent so that the solid content is in the range of 0.2 to 70% by mass.

  According to the present invention, it is possible to provide a binder for an electrode having a high binding force and a high binding force with an electrode constituent material even with a small amount of addition, whereby an electrode material slurry with good properties and good properties can be provided. And a battery exhibiting higher performance such as a low battery internal resistance characteristic (DCR characteristic).

  Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

In this specification, “(meth) acryl” means that both “acryl and methacryl” are included, and “(meth) allyl” means that both “allyl and methallyl” are included. means. The “(meth) acryl group” is also referred to as a (meth) acryloyl group. This “(meth) acryloyl group” includes both an acryloyl group (CH ₂ ═CH—C (═O) —) and a methacryloyl group (CH ₂ ═C (CH ₃ ) —C (═O) —). Means that. The “(meth) allyl group” means an allyl group (CH ₂ ═CH—CH ₂ —, also referred to as 2-propenyl group) and a methallyl group (CH ₂ ═C (CH ₃ ) —CH ₂ —). Means both are included.

  The numerical range in this specification shall include a lower limit value and an upper limit value unless otherwise specified. In the present specification, “parts” and “%” are based on mass unless otherwise specified.

  In the present specification, for easy understanding, a symbol indicating a monomer unit (component) contained in a polymer (polymer) may also be used for a raw material compound.

1. Electrode Binder An electrode binder according to an embodiment of the present invention (hereinafter, also simply referred to as “binder”) includes a monomer unit derived from (a) an ethylenically unsaturated carboxylic acid ester compound, which will be described later. And (b) copolymer latex particles having monomer units derived from an ethylenically unsaturated sulfonic acid compound and (c) monomer units derived from an ethylenically unsaturated carboxylic acid compound.

[Particle size]
The median diameter of the copolymer latex particles is in the range of 50 nm to 200 nm. The median diameter is a particle diameter (volume-based cumulative frequency 50% diameter, hereinafter also referred to as “D50”) measured by a dynamic light scattering method in accordance with JIS Z8825: 2013. More preferably, D50 can be in the range of 60 nm to 190 nm, in the range of 70 nm to 180 nm, in the range of 80 nm to 170 nm, or in the range of 90 nm to 160 nm, and more preferably in the range of 100 nm to 150 nm. If the D50 is too small, less than 50 nm, the colloidal stability of the copolymer latex particles is inferior, and aggregates are generated during preparation of the electrode material slurry, which is not preferable. On the other hand, if D50 is too large, more than 200 nm, the binding to the active material may be weakened and peeling may occur, and further, the copolymer latex particles may cover the active material and increase the battery internal resistance. In addition, it is not preferable because battery characteristics are deteriorated. The particle size distribution is preferably unimodal.

[Form and production method of copolymer latex particles]
The binder according to this embodiment includes copolymer latex particles dispersed in an aqueous solvent (so-called polymer emulsion form). The solid content (resin content) in the aqueous solvent in the form is preferably, for example, in the range of 0.2 to 70% by mass, more preferably in the range of 0.5 to 70% by mass, and still more preferably in the range of 1 to 65% by mass. The range of 10 to 60% by mass is still more preferable.

  The dispersion medium is preferably water from the viewpoint of good dispersibility. In addition to water, alcohols such as ethyl alcohol, isopropyl alcohol and n-propyl alcohol, ketones such as diacetone alcohol and γ-butyrolactone, ethers and glycol ethers may be used as the dispersion medium. These can be used by mixing with water as the main dispersion medium.

  The method for producing the dispersed copolymer latex particles is not particularly limited, and can be produced by a known method such as an emulsion polymerization method, a suspension polymerization method, an emulsion dispersion method, etc. It is desirable to set conditions so as to increase the number of reaction fields by adjusting the blending amount of the body, monomer), the addition amount of the surfactant, and the like. In addition to using a polymerization initiator to polymerize raw materials and obtain copolymer latex particles, additives such as a molecular weight modifier and an emulsifier may be used. From the viewpoint of ease of production and good properties of the resulting product, it is preferable to use an emulsion polymerization method. In particular, a part of the raw material monomer, water, and emulsifier are mixed and dispersed in advance during the polymerization. It is more preferable to use an emulsion polymerization method by an emulsion dropping method to be added.

  Examples of polymerization initiators include organic compounds such as lauroyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate and 3,3,5-trimethylhexanoyl peroxide. Examples thereof include peroxides, azo compounds such as α, α′-azobisisobutyronitrile, ammonium persulfate, and potassium persulfate. A polymerization initiator may be used individually by 1 type, and may be used in combination of 2 or more types.

  The binder according to this embodiment is preferably in the range of pH 5 to 10 and more preferably in the range of pH 5 to 9 from the viewpoint of the corrosivity of the current collector metal, the dispersion stability of the active material, and the like. In order to adjust the pH of the binder, a basic aqueous solution such as ammonia or alkali metal hydroxide may be included. Examples of such alkali metal hydroxides include sodium hydroxide and potassium hydroxide.

In preferable embodiment, what includes the following processes can be implemented as a manufacturing method of a binder. That is,
The mass ratio (a) :( c) = 99.9: (a) ethylenically unsaturated carboxylic acid ester compound, (b) ethylenically unsaturated sulfonic acid compound and (c) ethylenically unsaturated carboxylic acid compound. Preparing to be in the range of 0.1 to 99.0: 1.0;
In the aqueous solvent, adding 1 to 15% by mass of the total amount of the component (a), the component (b) and the component (c), and performing initial polymerization,
A copolymer latex having a median particle diameter in the range of 50 nm or more and 200 nm or less by adding the remaining amounts of the component (a), the component (b), and the component (c) to the initially polymerized system. Preparing the particles;
And dispersing the copolymer latex particles in the aqueous solvent so that the solid content is in the range of 0.2 to 70% by mass.

  In a more preferred embodiment, the amount of the raw material used in the initial polymerization described above may be in the range of 1 to 14% by mass, more preferably in the range of 2 to 10% by mass. The temperature in the initial polymerization can be set according to the type of polymerization initiator to be used. For example, when ammonium persulfate is used as the polymerization initiator, it is in the range of 70 to 90 ° C, more preferably in the range of 75 to 83 ° C. More preferably, it can be set in the range of 78 to 80 ° C.

  The temperature in the main polymerization described above can also be set according to the type of polymerization initiator used. In a more preferred embodiment, the temperature in the main polymerization when ammonium persulfate is used as a polymerization initiator is in the range of 70 to 90 ° C, more preferably in the range of 75 to 85 ° C, and still more preferably 80 ° C. it can.

  Thus, by carrying out the initial polymerization and the main polymerization separately, copolymer latex particles having desirable physical properties can be obtained.

[Blend ratio of raw material monomers constituting copolymer latex particles]
In order to make the particle diameter of the copolymer latex particles in the specific range, the mass ratio of the component (a) and the component (c) is in the range of 99.9: 0.1 to 99.0: 1.0, Preferably it is the range of 99.5: 0.5-99.1: 0.9. The content of the component (a) relative to the total amount of the components (a), (b), and (c) is preferably in the range of 50% by mass to less than 100% by mass, and in the range of 60 to 98% by mass. More preferably, it is more preferably in the range of 70 to 98% by mass.

  In addition, the content of (c) with respect to the total amount of components (a), (b), and (c) is preferably in the range of 0.1 to 1.0% by mass, and 0.2 to 1.0. The range is more preferably in the range of mass%, and further preferably in the range of 0.5 to 1.0 mass%. Thus, due to the small content of the component (c), the electrode material slurry containing the binder of this embodiment is excellent in storage stability, and excellent in the smoothness of the coating film when the slurry is applied. It will be. Moreover, it is preferable that the total amount of (a) component and (c) component is 70 mass% or more with respect to the total amount of (a), (b), (c) component.

  In preferable embodiment, content of (b) component with respect to the total amount of (a), (b), (c) component can be made into the range of 0.03-3 mass%, and 1-2 mass% Or in the range of 1 to 1.5 mass%. Further, the ratio of the total amount of the component (a) and the component (b) to the total of the components (a), (b), and (c) is preferably 70% by mass or more, and more preferably 80% by mass or more. More preferably, it is 90 mass% or more, More preferably, it is 95 mass% or more.

[Component (a): Monomer unit derived from an ethylenically unsaturated carboxylic acid ester compound]
The ethylenically unsaturated carboxylic acid ester compound that is a raw material for the component (a) is not particularly limited. The ethylenically unsaturated carboxylic acid ester compound can be obtained from an ethylenically unsaturated carboxylic acid and (mono or di) alcohol by a known production method, but the ester compound is derived from an ethylenically unsaturated carboxylic acid. And a portion derived from alcohol. Moreover, what was manufactured in this way can also be used for the said ester compound, and a commercial item may be used for it.

  The component (a) preferably includes one or a combination of two or more of (a1) to (a4) described later. That is, (a1) a monomer unit derived from an ethylenically unsaturated carboxylic acid ester compound having an alkyl group having a hydroxyl group at an alcohol-derived site in the ester structure, (a2) a (meth) acryl group and / or (meth) A monomer unit derived from an ethylenically unsaturated carboxylic acid ester compound having a plurality of allyl groups; (a3) an ethylenically unsaturated carboxylic acid ester compound having an alkyl group having 8 or more carbon atoms in an alcohol-derived site in the ester structure; And (a4) a monomer unit derived from an ethylenically unsaturated carboxylic acid ester compound having an alkyl group having 1 to 7 carbon atoms in the alcohol-derived site in the ester structure. Most preferably, component (a) includes both (a1), (a2), (a3), and (a4).

  In the present disclosure, “the site derived from the alcohol in the ester structure” means that the carboxylic acid ester (R—COO—R ′) is typically a reaction between the carboxylic acid (R—COOH) and the alcohol (R′—OH). This refers to the site on the side derived from this alcohol, based on being generated by

  In the component (a1), the alkyl group having a hydroxyl group is preferably linear and branched, and more preferably linear. Further, the alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms. The number of hydroxyl groups is not particularly limited, but is preferably in the range of 1 to 2. The site derived from the ethylenically unsaturated carboxylic acid is preferably acrylic acid.

  As the component (a1), 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) It is preferable to include one or more of hydroxycyclohexyl acrylate, and it is more preferable to include 2-hydroxyethyl acrylate. When the component (a1) is contained, the content is preferably 1 to 10% by mass in the total amount of raw material monomers (that is, the total amount of the components (a), (b) and (c), the same applies hereinafter), and 2 to 8%. The mass% is more preferable, and 3 to 7 mass% is more preferable.

  The component (a2) is an ethylenically unsaturated carboxylic acid ester compound having two or more of either (meth) acryl group or (meth) allyl group, or two or more of both. The component (a2) preferably has two (meth) acryl groups and / or (meth) allyl groups, has two (meth) acryl groups, or one (meth) acryl group and one (meth) It is more preferable to have an allyl group.

The structure of the component (a2) is, for example, “(meth) acryl group and / or (meth) allyl group” —O— “alkylene group—O” _n — “(meth) acryl group and / or (meth) allyl group”. Can be expressed as

  Here, the “alkylene group” in the “alkylene group-O” which is a site derived from alcohol is preferably linear or branched, and more preferably linear. Further, the “alkylene group” preferably has 1 to 5 carbon atoms, more preferably 1 to 2 carbon atoms. The n is preferably an integer in the range of 0 to 4, more preferably an integer in the range of 0 to 2, and even more preferably 0 or 1.

  As the component (a2), (meth) acrylic acid (meth) allyl, di (meth) acrylic acid ethylene glycol (for example, ethylene glycol dimethacrylate), di (meth) acrylic acid propylene glycol, di (meth) acrylic acid tetra It is preferable to include one or more of methylene glycol, dimethacrylic acid-1,3-butylene glycol and the like, and it is more preferable to include ethylene glycol dimethacrylate (ethylene glycol dimethacrylate). When the component (a2) is used, the content is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, and further preferably 2 to 5% by mass in the total amount of raw material monomers.

  The component (a3) excludes the component corresponding to the component (a1). As the component (a3), those having 8 to 18 carbon atoms in the alkyl group at the alcohol-derived site in the ester structure are preferable, those having 8 to 12 are more preferable, and those having 8 to 10 are more preferable. The alkyl group is preferably linear or branched, and more preferably branched.

  As the component (a3), 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, t-octyl (meth) acrylate, n-dodecyl (meth) acrylate, n-octadecyl acrylate, ( It preferably contains one or more of nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, and isodecyl (meth) acrylate, and more preferably contains 2-ethylhexyl (meth) acrylate. It is particularly preferable to contain 2-ethylhexyl methacrylate. When the component (a3) is used, the content is preferably 10 to 95% by mass, more preferably 60 to 90% by mass, and still more preferably 70 to 85% by mass in the total amount of raw material monomers.

  The component (a4) excludes the component corresponding to the component (a1). (A4) As a component, the (meth) acrylic acid ester which has a C1-C7 alkyl group in the site | part derived from the alcohol in ester structure is mentioned. The alkyl group is preferably a straight chain or branched chain, and more preferably a straight chain. Furthermore, as for carbon number of the said alkyl group, 1-3 are preferable. The site derived from the ethylenically unsaturated carboxylic acid in the ester structure is preferably methacrylic acid, more preferably methyl methacrylate.

  Preferred examples of the component (a4) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth) Examples thereof include one or more selected from the group consisting of hexyl acrylate and heptyl (meth) acrylate. When the component (a4) is used, the content is preferably 1 to 30% by mass, more preferably 1 to 10% by mass, and further preferably 2 to 8% by mass in the total amount of raw material monomers.

  With the component (a) described above, the storage stability of the electrode material slurry produced from the binder of the present embodiment is excellent, and when the slurry is applied, the coating film has excellent binding properties. Played.

[(B) Monomer unit derived from ethylenically unsaturated sulfonic acid compound]
Examples of the component (b) include vinyl sulfonic acid, p-styrene sulfonic acid, (meth) allyl sulfonic acid, polyoxyethylene-1- (allyloxymethyl) alkyl sulfonate, polyoxyalkylene alkenyl ether sulfonate, Examples thereof include one or more selected from polyoxyethylene allyloxymethylalkoxyethyl sulfonate, alkyl allyl sulfosuccinate, polyoxyalkylene (meth) acrylate sulfonate, and the like, and salts thereof. Examples of the salt include alkali metal salts (Na, K, etc.), alkaline earth metal salts, ammonium salts, and the like.

  Among the above-mentioned examples of the component (b), p-styrene sulfonic acid, polyoxyethylene-1- (allyloxymethyl) alkyl sulfonate, polyoxyalkylene alkenyl ether sulfonate, polyoxyethylene allyloxymethylalkoxyethyl It is preferable to include one or more of sulfonic acid esters and salts thereof, and it is more preferable to include polyoxyethylene-1- (allyloxymethyl) alkylsulfonic acid esters and salts thereof.

[(C) ethylenically unsaturated carboxylic acid]
Examples of the component (c) include (meth) acrylic acid.

  By using the raw material monomer as described above as the raw material of the binder, it becomes possible to easily cause crosslinking in the binder. For example, when the components (a1) to (a4), (b), and (c) are used as monomer raw materials constituting the binder, it is considered that the component (a1) and other monomers are cross-linked.

2. Electrode Material Slurry An electrode material slurry according to an embodiment of the present invention contains the above-described binder, conductive additive, and active material. At this time, additives and the like may be further mixed. Further, the electrode material slurry of the present embodiment is preferably used for forming electrodes in secondary batteries such as lithium ion secondary batteries and nickel metal hydride secondary batteries, and electric double layer capacitors, and more preferably lithium ion. Used to form secondary battery electrodes.

(Active material)
Any active material can be used as long as it is used in an ordinary secondary battery or capacitor. As this active material, a positive electrode active material and a negative electrode active material are used.

As the positive electrode active material, as a general _{formula, A a M m Z z O} o N n F f (A is an alkali metal element; M is a transition metal element (Fe, Mn, V, Ti , Mo, W, Zn) or Z is a non-metallic element (P, S, Se, As, Si, Ge, B); O is an oxygen element; N is a nitrogen element; F is a fluorine element; a, m, z, n, f ≧ 0; o> 0).

Moreover, as a positive electrode active material of a lithium ion secondary battery, for example, a lithium metal composite oxide mainly composed of Li _x MetO ₂ can be given. Met in this case is one or more transition metals, for example, one or more selected from cobalt, nickel, manganese and iron, and x is usually 0.05 ≦ x ≦ 1. A range of zero. Specific examples of such a lithium metal composite oxide include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiFeO _{2 and the} like.

Further, for example, olivine-type lithium compounds such as olivine-type lithium phosphate compounds represented by olivine-type lithium iron phosphate (LiFePO ₄ ) and LiMetPO ₄ (Met = V, Fe, Ni, Mn), TiS ₂ , MoS ₂ Well-known positive electrode active materials such as metal sulfides and metal oxides not containing lithium, such as NbS ₂ and V ₂ O ₅ , and composite metals such as NbSe ₂ . Of these positive electrode active materials, LiFePO ₄ is suitable for the binder of the present embodiment.

The negative electrode active material of the lithium ion secondary battery is selected from lithium metal, Li and alloys of low melting point metals such as Pb, Bi and Sn, lithium alloys such as Li-Al alloys, carbonaceous materials, etc. A seed | species or 2 or more types is mentioned. As the carbonaceous negative electrode active material, any material that can occlude and release lithium ions, which are the main components of battery operation, can be used. Carbon-based compounds such as graphitizable carbon, non-graphitizable carbon, polyacene, polyacetylene, pyrene, An aromatic hydrocarbon compound containing an acene structure such as perylene is preferably used. Various carbonaceous materials can be used. Further, lithium titanate represented by Li _x Ti _y O _z or the like, or a metal oxide compound such as SiO _x or SnO _x can also be used.

  Examples of the positive electrode active material of the nickel metal hydride secondary battery include nickel hydroxide. Examples of the negative electrode active material of the nickel metal hydride secondary battery include a hydrogen storage alloy. Examples of the positive electrode active material and the negative electrode active material of the electric double layer capacitor include activated carbon.

The amount of the binder in the electrode material slurry of the present embodiment is in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the active material as the solid content of the binder (that is, the resin content of the binder). Is preferred. When the amount of the binder is 0.1 parts by mass or more, an active material such as LiFePO ₄ is easily dispersed uniformly in the coating solution, and the strength of the dried film after coating is easily obtained. Moreover, since it can suppress that the amount of active materials in a positive electrode reduces that the amount of binders is 10 mass parts or less, it can suppress that charging capacity decreases.

(Conductive aid)
The electrode material slurry of this embodiment can contain a conductive additive. Examples of such conductive aids include carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black, carbon nanotubes, graphite powder, and various graphites. These conductive assistants may be used in combination of two or more.

(Composite material)
The electrode material slurry of the present embodiment may contain a composite material in which a plurality of conductive assistants and active materials are connected in order to improve the conductivity imparting ability of the conductive assistant and the active material and the conductivity. For example, in the case of a lithium ion secondary battery electrode material slurry, this composite material is a composite of a carbon black composite in which fibrous carbon and carbon black are connected, and a olivine-type lithium iron phosphate further coated with carbon on this composite. Examples include an integrated composite material. A carbon black composite in which fibrous carbon and carbon black are linked can be obtained, for example, by firing a mixture of fibrous carbon and carbon black. Moreover, it can also be set as the composite material which baked the mixture of this carbon black composite and positive electrode active materials, such as olivine type lithium iron phosphate.

  The carbon black composite and the composite material obtained by combining and integrating the carbon black composite and the olivine-type lithium iron phosphate further coated with carbon are generally water-based electrodes having generally good properties due to the problem of dispersibility. It was difficult to obtain a material slurry. However, a good electrode material slurry can be obtained by using the binder.

(Additive)
The electrode material slurry of the present embodiment may contain a viscosity modifier, a fluidizing agent, and the like as necessary. Examples of such additives include water-soluble polymers such as polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose, and polymethacrylic acid.

3. Electrode The electrode which concerns on embodiment of this invention is manufactured using the said electrode material slurry. Specifically, the electrode of the present embodiment can be obtained by applying the electrode material slurry on a current collector and drying to laminate an electrode mixture layer. In addition, a positive electrode is manufactured with the electrode material slurry containing the said positive electrode active material, and a negative electrode is manufactured with the electrode material slurry containing the said negative electrode active material. The electrode of the present embodiment is preferably used for the production of secondary batteries such as lithium ion secondary batteries and nickel hydride secondary batteries, and electric double layer capacitors, and is used for the production of lithium ion secondary batteries. Is more preferable.

(Current collector)
In general, aluminum is preferably used for the positive electrode current collector. Usually, copper or aluminum is preferably used for the negative electrode current collector. The shape of the current collector is not particularly limited, but a foil shape, a net shape, an expanded metal, or the like can be used. The shape of the current collector is preferably one having a large void area such as a net or an expanded metal, and the thickness is preferably about 0.001 to 0.03 mm from the viewpoint of facilitating holding of the electrolytic solution after bonding.

(Method for manufacturing electrode)
As a method for applying the electrode material slurry, a general method can be employed. Examples thereof include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. Of these, blade method (comma roll or die cut), knife method and extrusion method are preferable. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting the said coating method according to the solution physical property and drying property of a binder. The application may be performed on one side or both sides, and in the case of both sides, each side may be sequentially or simultaneously. Further, the application may be continuous, intermittent, or striped. The application thickness, length, and width of the electrode material slurry may be appropriately determined according to the size of the battery. For example, the application thickness of the electrode material slurry, that is, the thickness of the mixture layer can be in the range of 10 μm to 500 μm.

  As a method for drying the electrode material slurry, a generally adopted method can be used. In particular, it is preferable to use hot air, vacuum, infrared rays, far-infrared rays, electron beams and low-temperature air alone or in combination. In this embodiment, by using an electrode material slurry prepared using water as a solvent, drying can be performed at a temperature of about 50 to 130 ° C., and energy for drying can be reduced.

The electrode can be pressed as needed. As the pressing method, a generally adopted method can be used, and a die pressing method and a calendar pressing method (cold or hot roll) are particularly preferable. Although a press pressure is not specifically limited, 0.2-3 t / cm < ² > is preferable.

4). Secondary battery and capacitor A secondary battery and a capacitor according to an embodiment of the present invention each include the electrode. Examples of the secondary battery include a lithium ion secondary battery and a nickel hydride secondary battery, and examples of the capacitor include an electric double layer capacitor. Among these, the electrode is preferably used for a lithium ion secondary battery.

  In addition, the secondary battery and the capacitor of the present embodiment are configured to include the electrode (positive electrode and negative electrode), a separator, and an electrolyte solution (hereinafter sometimes simply referred to as “electrolyte solution”). Is preferred. Note that at least one of the positive electrode and the negative electrode according to the above embodiment may be the electrode of the present invention, and in this case, an electrode other than the above embodiment may be used as the other electrode.

(separator)
Any separator can be used as long as it has sufficient strength, such as an electrically insulating porous film, a net, and a nonwoven fabric. In particular, it is preferable to use a material that has low resistance to ion migration of the electrolytic solution and excellent in solution holding. The material is not particularly limited, and examples thereof include inorganic fibers such as glass fibers or organic fibers, synthetic resins such as polyethylene, polypropylene, polyester, polytetrafluoroethylene, and polyflon, and layered composites thereof. From the viewpoint of adhesion and safety, polyethylene, polypropylene, or a layered composite film thereof is desirable.

(Electrolyte)
As the electrolytic solution in the case of a lithium ion secondary battery, one having a non-aqueous solvent such as an organic solvent containing a lithium salt supporting electrolyte (hereinafter sometimes simply referred to as “electrolyte”) is preferable. It is. The electrolyte in the electrolyte solution in this case, any known lithium salt can be _{used, LiClO 4, LiBF 4, LiBF} 6, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl ₁₀ , LiAlCl ₄ , LiCl, LiBr, LiI, LiB (C ₂ H ₅ ) ₄ , LiCF ₃ SO ₃ , LiCH ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , lithium lower fatty acid carboxylate and the like can be mentioned, but are not particularly limited.

  Examples of the electrolytic solution in the case of a nickel metal hydride battery include aqueous solutions of electrolytes such as sodium hydroxide, lithium hydroxide, and potassium hydroxide. The electrolytic solution in the case of the electric double layer capacitor is configured to have a non-aqueous solvent such as an organic solvent containing an electrolyte such as an ammonium salt or a sulfonium salt. As the organic solvent in this case, one kind or two or more kinds of mixed solvents such as carbonates, alcohols, nitriles, amides and ethers can be used.

  Examples of the organic solvent for dissolving the electrolyte in the case of a lithium ion secondary battery include carbonates, lactones such as γ-butyrolactone, ethers, sulfoxides such as dimethyl sulfoxide, oxolanes, nitrogen-containing compounds, and esters. , Inorganic acid esters, amides, glymes, ketones, sulfolanes such as sulfolane, oxazolidinones such as 3-methyl-2-oxazolidinone, and one or more mixed solvents such as sultone Can do.

  Specific examples of carbonates include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

  Examples of ethers include trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran and the like.

  Examples of oxolanes include 1,3-dioxolane and 4-methyl-1,3-dioxolane.

  Nitrogen-containing compounds include acetonitrile, nitromethane, N-methyl-2-pyrrolidone and the like.

  Examples of the esters include methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, and phosphoric acid triester.

  Examples of inorganic acid esters include sulfate esters and nitrate esters.

  Examples of amides include dimethylformamide and dimethylacetamide.

  Examples of the glymes include diglyme, triglyme, and tetraglyme.

  Examples of ketones include acetone, diethyl ketone, methyl ethyl ketone, and methyl isobutyl ketone.

  Examples of sultone include 1,3-propane sultone, 4-butane sultone, naphtha sultone and the like.

As these non-aqueous electrolytes, in the case of lithium ion secondary batteries, non-aqueous electrolytes in which LiPF ₆ is dissolved in carbonates are preferred, and the electrolyte concentration varies depending on the electrode and electrolyte used, but 0.5-3 Mole / l is preferred.

  Hereinafter, although an example and a comparative example in connection with an embodiment of the present invention are given and an embodiment is described still in detail, the above-mentioned embodiment is not limited by these.

(1) Preparation of binder <Example 1>
A temperature-controllable container equipped with a stirrer was charged with 100 parts by mass of purified water (hereinafter simply referred to as “parts”) and 0.2 part of ammonium persulfate. 84 parts of 2-ethylhexyl acrylate as component (a3), 5 parts of 2-hydroxyethyl acrylate as component (a1), 2 parts of ethylene glycol dimethacrylate as component (a2), 5 parts of methyl methacrylate as component (a4) , (B) 3 parts polyoxyethylene-1- (allyloxymethyl) alkyl sulfonate ammonium salt (trade name “Aqualon KH-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.8 parts of acid was prepared. An amount corresponding to 2% by mass (hereinafter abbreviated as “2% amount”, etc.) of the total of the prepared components (a), (b), and (c) was added, Initial polymerization was performed at temperature. Thereafter, the remaining components (a), (b), and (c) were added, and main polymerization was performed at 80 ° C. for 6 hours. The polymerization conversion after the main polymerization was 99%. Thereafter, the mixture was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a polymer emulsion (solvent dispersion) type binder having a solid content of 50% by mass.

<Example 2>
100 parts of purified water and 0.2 part of ammonium persulfate were charged into a temperature-controllable container equipped with a stirrer. 84 parts of 2-ethylhexyl acrylate as component (a3), 5 parts of 2-hydroxyethyl acrylate as component (a1), 2 parts of ethylene glycol dimethacrylate as component (a2), 5 parts of methyl methacrylate as component (a4) 3 parts of polyoxyethylene-1- (allyloxymethyl) alkylsulfonic acid ester ammonium salt (above “Aqualon KH-10”) as component (b) and 0.8 parts of methacrylic acid as component (c) were prepared. 5% of the total of the prepared components (a), (b), and (c) was added, and initial polymerization was performed at a temperature of 78 to 80 ° C. Thereafter, the remaining components (a), (b), and (c) were added, and main polymerization was performed at 80 ° C. for 6 hours. The polymerization conversion after the main polymerization was 99%. Thereafter, the solution was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a solvent-dispersed binder having a solid content of 50% by mass.

<Example 3>
100 parts of purified water and 0.2 part of ammonium persulfate were charged into a temperature-controllable container equipped with a stirrer. 84 parts of 2-ethylhexyl acrylate as component (a3), 5 parts of 2-hydroxyethyl acrylate as component (a1), 2 parts of ethylene glycol dimethacrylate as component (a2), 5 parts of methyl methacrylate as component (a4) 3 parts of polyoxyethylene-1- (allyloxymethyl) alkylsulfonic acid ester ammonium salt (above “Aqualon KH-10”) as component (b) and 0.8 parts of methacrylic acid as component (c) were prepared. 10% of the total of the prepared components (a), (b), and (c) was added, and initial polymerization was performed at a temperature of 78 to 80 ° C. Thereafter, the remaining components (a), (b), and (c) were added, and main polymerization was performed at 80 ° C. for 6 hours. The polymerization conversion after the main polymerization was 99%. Thereafter, the solution was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a solvent-dispersed binder having a solid content of 50% by mass.

<Example 4>
100 parts of purified water and 0.2 part of ammonium persulfate were charged into a temperature-controllable container equipped with a stirrer. 82 parts of 2-ethylhexyl methacrylate as component (a3), 5 parts of 2-hydroxyethyl acrylate as component (a1), 5 parts of ethylene glycol dimethacrylate as component (a2), 5 parts of methyl methacrylate as component (a4) 3 parts of polyoxyethylene-1- (allyloxymethyl) alkylsulfonic acid ester ammonium salt (above “Aqualon KH-10”) as component (b) and 0.8 parts of methacrylic acid as component (c) were prepared. 2% of the total of the prepared components (a), (b), and (c) was added, and initial polymerization was performed at a temperature of 78 to 80 ° C. Thereafter, the remaining components (a), (b), and (c) were added, and main polymerization was performed at 80 ° C. for 6 hours. The polymerization conversion after the main polymerization was 99%. Thereafter, the solution was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a solvent-dispersed binder having a solid content of 50% by mass.

<Example 5>
100 parts of purified water and 0.2 part of ammonium persulfate were charged into a temperature-controllable container equipped with a stirrer. 82 parts of 2-ethylhexyl methacrylate as component (a3), 5 parts of 2-hydroxyethyl acrylate as component (a1), 5 parts of ethylene glycol dimethacrylate as component (a2), 5 parts of methyl methacrylate as component (a4) 3 parts of polyoxyethylene-1- (allyloxymethyl) alkylsulfonic acid ester ammonium salt (above “Aqualon KH-10”) as component (b) and 0.8 parts of methacrylic acid as component (c) were prepared. 10% of the total of the prepared components (a), (b), and (c) was added, and initial polymerization was performed at a temperature of 78 to 80 ° C. Thereafter, the remaining components (a), (b), and (c) were added, and main polymerization was performed at 80 ° C. for 6 hours. The polymerization conversion after the main polymerization was 99%. Thereafter, the solution was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a solvent-dispersed binder having a solid content of 50% by mass.

<Example 6>
100 parts of purified water and 0.2 part of ammonium persulfate were charged into a temperature-controllable container equipped with a stirrer. 79 parts of 2-ethylhexyl methacrylate as component (a3), 5 parts of 2-hydroxyethyl acrylate as component (a1), 8 parts of ethylene glycol dimethacrylate as component (a2), 5 parts of methyl methacrylate as component (a4) 3 parts of polyoxyethylene-1- (allyloxymethyl) alkylsulfonic acid ester ammonium salt (above “Aqualon KH-10”) as component (b) and 0.8 parts of methacrylic acid as component (c) were prepared. 10% of the total of the prepared components (a), (b), and (c) was added, and initial polymerization was performed at a temperature of 78 to 80 ° C. Thereafter, the remaining components (a), (b), and (c) were added, and main polymerization was performed at 80 ° C. for 6 hours. The polymerization conversion after the main polymerization was 99%. Thereafter, the solution was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a solvent-dispersed binder having a solid content of 50% by mass.

<Example 7>
100 parts of purified water and 0.2 part of ammonium persulfate were charged into a temperature-controllable container equipped with a stirrer. (A3) component 2-ethylhexyl methacrylate 83 parts, (a1) component 2-hydroxyethyl acrylate 5 parts, (a2) component ethylene glycol dimethacrylate 5 parts, (a4) component methyl methacrylate 5 parts , 1.5 parts of polyoxyethylene-1- (allyloxymethyl) alkyl sulfonate ammonium salt (above “Aqualon KH-10”) as component (b) and 0.8 parts of methacrylic acid as component (c) are prepared. did. 10% of the total of the prepared components (a), (b), and (c) was added, and initial polymerization was performed at a temperature of 78 to 80 ° C. Thereafter, the remaining components (a), (b), and (c) were added, and main polymerization was performed at 80 ° C. for 6 hours. The polymerization conversion after the main polymerization was 99%. Thereafter, the solution was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a solvent-dispersed binder having a solid content of 50% by mass.

<Comparative Example 1>
100 parts of purified water and 0.2 part of ammonium persulfate were charged into a temperature-controllable container equipped with a stirrer. (A3) component 2-ethylhexyl methacrylate 83 parts, (a1) component 2-hydroxyethyl acrylate 5 parts, (a2) component ethylene glycol dimethacrylate 5 parts, (a4) component methyl methacrylate 5 parts , 1.5 parts of polyoxyethylene-1- (allyloxymethyl) alkyl sulfonate ammonium salt (above “Aqualon KH-10”) as component (b) and 0.8 parts of methacrylic acid as component (c) are prepared. The whole amount was polymerized at 80 ° C. for 6 hours. The polymerization conversion rate was 99%. The solution was neutralized to pH 7 with a 10% aqueous potassium hydroxide solution to obtain a solvent-dispersed binder having a solid content of 50% by mass.

(2) Evaluation of copolymer latex particles (Measurement of particle diameter)
The particle size distribution of the copolymer latex particles was measured by a dynamic light scattering method in accordance with JIS Z8825: 2013. LA-950V2 manufactured by HORIBA was used as the measuring device, and the volume-based median diameter (50% particle diameter, D50) was calculated from the cumulative distribution curve. The measurement was performed according to the following procedure.

(Measurement procedure)
First, the copolymer latex particles are diluted in about 150 mL of pure water so that the sample concentration is 0.1 to 1.0% by mass. After dilution, it was filtered through a 200 mesh wire mesh. Using this filtrate, the measurement was performed with the above measuring apparatus. The measurement was performed in the range of laser light transmittance (R): 93.5 to 94.5%.

(3) Preparation of positive electrode material slurry 5 parts of the obtained binder, 2 parts of carboxymethyl cellulose, 84 parts of LiFePO ₄ , 7 parts of acetylene black and 2 parts of fibrous carbon were mixed to produce a positive electrode material having a solid content of 42%. A slurry was prepared.

(4) Evaluation of positive electrode material slurry Storage stability of slurry The prepared positive electrode material slurry was sealed and allowed to stand, and the properties of the slurry were confirmed after one week. “No” for gelation, coarse grain generation, and extreme viscosity change, “No” for viscosity change but no coarse grain generation, good properties, no coarse grain generation, small viscosity change The product was evaluated as “good” and visually evaluated for the storage stability of the slurry.

Smoothness of coating film The prepared positive electrode material slurry was applied to a positive electrode current collector (aluminum foil) having a thickness of 200 μm. At that time, perform the visual evaluation with coarse particles that have streaks on the coated surface as `` impossible '', those that have some traces as `` good '', and those that do not have streaks as `` good ''. It was.

(5) Production of positive electrode Next, the prepared positive electrode material slurry was applied to one side of a positive electrode current collector (aluminum foil) having a thickness of 20 μm so that the mixture application amount was 140 g / m ² and dried. Thus, a positive electrode mixture layer was formed. This was pressed with a roll press so that the thickness of the positive electrode mixture layer was 64 μm, and cut into a circle with a diameter of 14 mm to produce a mixture electrode plate. In order to completely remove the residual solvent and non-volatile components, vacuum drying was performed at 120 ° C. for 14 hours to obtain a positive electrode. About the produced positive electrode, the adhesiveness (binding property) of the positive mix layer was evaluated with the following method.

(6) Evaluation of positive electrode Peel test Using the prepared positive electrode, a rectangle having a length of 200 cm and a width of 15 mm was cut out in the coating direction to obtain a test piece. An adhesive tape (895M manufactured by 3M) was attached to the front surface of the test piece on the electrode material layer side. The end of the current collector foil was fixed, and the stress when the tape end at one end of the test piece was pulled upward at a pulling speed of 200 mm / min and peeled was measured. It was judged that the greater the stress, the greater the binding force of the electrode material layer to the current collector. The unit is N / m.

Winding bending test A stainless steel rod (10 to 2φ) having a different thickness was placed on a clamp so as to be parallel to the ground, and the prepared positive electrode was hung on the stainless steel rod and suspended at both ends by 200 g. The thickness of the stainless bar where no cracks appeared in the electrode material layer was observed. It was judged that the smaller the thickness of the stainless bar, the greater the binding force with various substances in the electrode material layer. The unit is φ.

(7) Production of Lithium Ion Battery A lithium ion battery was produced using the positive electrode produced as described above and a disc-shaped lithium metal having a diameter of 15 mm as the negative electrode. The positive electrode and negative electrode were inserted into a coin cell, and LiPF ₆ as an electrolyte and a mixed solution of ethylene carbonate: diethylene carbonate: dimethylene carbonate = 1: 1: 1 (volume ratio) as an electrolyte were injected into the coin cell. The coin cell was crimped and sealed to produce a coin-type half-cell lithium ion battery.

(8) DCR characteristics (battery internal resistance)
Using the produced lithium ion battery, the voltage after 10 seconds when currents of 0.2, 0.4, 0.6, 0.8, and 1.0 mA were passed at 25 ° C. was measured. At this time, the SOC (depth of charge) was 25%. The battery internal resistance R was calculated from R = V / I, and the average value of R was determined. The same measurement was performed in an environment of −10 ° C.

(9) Electrode resistance The electrode was cut and processed into a disk shape of φ10 mm. The obtained disc-shaped electrode was sandwiched between cylindrical SUS electrodes having a diameter of 13 mm and a length of 5 mm, and was fixed in a SUS bipolar cell. Next, a SUS bipolar cell was installed in a thermostat set at 25 ° C., and an applied current value of 0.2, 0.4, 0.6, 0.8 and a Solartron 12608W electrochemical measurement system was used. A constant current polarization test was performed at 1.0 mA for 10 seconds each. An IV plot was performed from the test results, and an electrode resistance value was calculated from the following equation (1) from the slope of the obtained approximate straight line.
Electrode resistance value = (slope of IV plot) × (electrode area) (1)

  For Examples 1 to 7 and Comparative Example 1, polymerization formulations and evaluation results are summarized in Table 1 below.

  From the above results, in the comparative example in which the median diameter of the copolymer latex particles does not satisfy the conditions, not only the smoothness of the coating film is inferior, but also any of peel evaluation, winding bending evaluation, battery internal resistance, and electrode plate resistance Was also inferior to the examples.

  According to the binder of this embodiment, an electrode material slurry having very good storage stability and smoothness of the coating film is provided. In addition, by appropriately adjusting the median diameter of the copolymer latex particles, when the electrode material slurry of the present embodiment is coated on the current collector to form the mixture layer, the mixture layer is bonded. It is possible to obtain an electrode excellent in adherence (adhesiveness).

  Further, by using this electrode, it is possible to obtain a lithium ion secondary battery, a nickel hydride secondary battery, an electric double layer capacitor, and the like that are excellent in DCR characteristics and electrode plate resistance characteristics. Furthermore, according to the binder of this embodiment, it is thought that it can contribute also to obtaining a secondary battery with favorable battery cycle characteristics.

Claims (9)

(A) a monomer unit derived from an ethylenically unsaturated carboxylic acid ester compound;
(B) a monomer unit derived from an ethylenically unsaturated sulfonic acid compound;
(C) including copolymer latex particles having monomer units derived from an ethylenically unsaturated carboxylic acid compound as a form dispersed in an aqueous solvent,
The mass ratio of the component (a) and the component (c) is in the range of 99.9: 0.1 to 99.0: 1.0,
The solid content in the aqueous solvent is in the range of 0.2 to 70% by mass,
The binder for an electrode, wherein a median diameter of the copolymer latex particles is in a range of 50 nm to 200 nm.   The binder for electrodes according to claim 1 whose content of (c) ingredient is 0.1-1.0 mass% to the total amount of (a) ingredient, (b) ingredient, and (c) ingredient. .   The binder for electrodes according to claim 1 or 2, wherein the content of the component (b) is 0.03 to 3% by mass with respect to the total amount of the component (a), the component (b) and the component (c). .   The electrode material slurry containing the binder for electrodes of any one of Claim 1 to 3, a conductive support agent, and an active material.   The electrode material slurry according to claim 4, wherein the content of the electrode binder is 0.1 to 10 parts by mass with respect to 100 parts by mass of the active material as a solid content.   The electrode containing the application | coating drying layer of the electrode material slurry of Claim 4 or 5.   A secondary battery comprising the electrode according to claim 6.   An electric double layer capacitor comprising the electrode according to claim 6. The mass ratio (a) :( c) = 99.9: (a) ethylenically unsaturated carboxylic acid ester compound, (b) ethylenically unsaturated sulfonic acid compound and (c) ethylenically unsaturated carboxylic acid compound. Preparing to be in the range of 0.1 to 99.0: 1.0;
Adding 1 to 15% by mass of the total amount of the component (a), the component (b) and the component (c) in the aqueous solvent, and performing initial polymerization;
Copolymer latex particles having a median diameter in the range of 50 nm or more and 200 nm or less by adding the remaining amount of component (a), component (b) and component (c) to the initially polymerized system. Preparing a step;
And a step of dispersing the copolymer latex particles in the aqueous solvent so that the solid content is in the range of 0.2 to 70% by mass.