KR101433512B1 - Electrode binder composition, electrode slurry, electrode, and electrical storage device - Google Patents

Abstract

An object of the present invention is to provide an electrode binder composition capable of producing an electrode having excellent storage stability over a long period of time and having good adhesion and charge / discharge characteristics even when stored over a long period of time.
As a means for solving the problem, the binder composition for electrodes according to the present invention is a binder composition for producing an electrode for use in a power storage device, which comprises a polymer (A), an isothiazoline compound (B) , And the polymer (A) is a fluorine-containing polymer particle or a diene-based polymer particle. When the polymer (A) is a diene polymer particle, the concentration of the compound (B) in the binder composition is 50 ppm or more and less than 200 ppm.

Description

ELECTRODE BINDER COMPOSITION, ELECTRODE SLURRY, ELECTRODE, AND ELECTRICAL STORAGE DEVICE,

The present invention relates to a binder composition for electrodes, an electrode slurry containing the binder composition and an electrode active material, an electrode manufactured by applying and drying the slurry to a current collector, and a battery device having the electrode.

[0002] In recent years, a power storage device having a high voltage and a high energy density has been required as a power source for driving electronic devices. Particularly, lithium ion batteries and lithium ion capacitors are expected as power storage devices having high voltage and high energy density.

The electrode used in such an electricity storage device is usually produced by applying a mixture of an electrode active material and polymer particles functioning as a binder onto the collector surface and drying the same. The properties required for the polymer particles include the ability to bond the electrode active materials, the ability of the electrode active material layer and the current collector to adhere to each other, the resistance in the step of winding the electrode, and the subsequent cutting, (Hereinafter, simply referred to as " electrode active material layer "), and powder dropout resistance in which no fine powder of the electrode active material is generated. By satisfying these various required characteristics of the polymer particles, the degree of freedom of the structure design of the electrical storage device, such as the method of folding the obtained electrode and the setting of the winding radius, is increased, and miniaturization of the device can be achieved. It is also apparent from the experience that the performance of the electrode active material, the ability of the electrode active material layer and the current collector to adhere to each other, and the powder dropout resistance are almost proportional to each other. Therefore, in the present specification, the term " adhesion "

As a binder for electrodes, when a positive electrode is prepared, it is advantageous to use a fluorine-containing organic polymer excellent in oxidation resistance although the adhesion of polyvinylidene fluoride and the like is slightly inferior. On the other hand, in the case of producing the negative electrode, it is advantageous to use a (meth) acrylic acid-based polymer which is slightly inferior in oxidation resistance but has excellent adhesion.

Various techniques for improving the properties such as oxidation resistance and adhesion of the polymer used for the binder for electrodes as described above have been variously studied and proposed. For example, Japanese Patent Application Laid-Open No. 2011-3529 proposes a technique for simultaneously making use of polyvinylidene fluoride and a rubber-based polymer to make both the oxidation resistance and the adhesion of the negative electrode binder compatible. Japanese Patent Application Laid-Open No. 2010-55847 discloses a technique for improving the adhesion by dissolving polyvinylidene fluoride in a specific organic solvent, applying the solution on the surface of the current collector, and then removing the solvent at a low temperature Has been proposed. Further, Japanese Patent Laid-Open No. 2002-42819 proposes a technique for improving adhesion by applying a binder for electrodes having a structure having a side chain having a fluorine atom in a main chain containing a vinylidene fluoride copolymer .

Further, a technique of improving the above characteristics by controlling the binder composition (see Japanese Patent Application Laid-Open No. 2000-299109) and a technique of improving the above characteristics by using a binder having an epoxy group or a hydroxyl group (Japanese Patent Laid- 205722, and Japanese Patent Application Laid-Open No. 2010-3703).

On the other hand, in order to use the binder composition in an actual production line, it is necessary to store the binder composition for electrodes for a long time in a warehouse or the like as well as the above properties. Even in such a long-term storage, it is necessary that the binder composition for electrodes is not deteriorated by precipitation of the polymer or the like. As a technique for improving the storage stability, International Publication Nos. 2012/002451 and 2012-9775 disclose a method of using an isothiazoline-based compound.

However, according to the technique disclosed in Japanese Patent Laid-Open Publication No. 2011-3529 in which a fluorine-containing organic polymer and a rubber-based polymer are used in combination, although the adhesion is improved, the oxidation resistance of the organic polymer is greatly impaired. Therefore, Discharge characteristic is irreversibly deteriorated by repetition of charging and discharging. On the other hand, according to the techniques disclosed in JP-A-2010-55847 and JP-A-2002-42819 which use only a fluorine-containing organic polymer as a binder for electrodes, the level of adhesion is still insufficient.

Further, with the binder composition disclosed in Japanese Patent Application Laid-Open Nos. 2000-299109, 2010-205722 and 2010-3703, adhesion can be improved. However, The attached binder itself becomes a resistance component of the electrode, and it is difficult to maintain good charge-discharge characteristics for a long period of time.

In addition, International Publication Nos. WO02 / 002451 and JP-A-2012-9775 have evaluated the anticorrosive properties of a binder composition containing an isothiazoline compound, and as a result, It is. However, in International Publication Nos. WO02 / 002451 and JP-A-2012-9775, attention is paid to the characteristics of a battery device manufactured using a binder composition immediately after production, and the merit of the battery is evaluated, The characteristics of a battery device manufactured using a binder composition after storage for a long period of time, which become most important in the art, have not been studied at all. That is, in the publication of International Publication No. 2012/002451 and Japanese Patent Laid-Open Publication No. 2012-9775, the storage stability of the polymer particle dispersion is merely evaluated, and the storage device after long- Long-term storage stability as an " electrode-for-electrode " binder composition, such as whether or not it can be made, is still unclear.

The present invention solves the above problems, and it is possible to provide a binder composition for electrodes capable of producing an electrode having excellent storage stability over a long period of time and having good adhesion and charge / discharge characteristics even when stored over a long period of time.

The present invention has been made to solve at least some of the problems described above, and can be realized as the following application example.

[Application Example 1]

The binder composition for electrodes according to the first aspect of the present invention is characterized in that,

A binder composition for producing an electrode for use in a power storage device,

(A), an isothiazoline compound (B) and a liquid medium (C)

The polymer (A)

A repeating unit (Ma) derived from a fluorine-containing ethylenic monomer,

The repeating unit (Mb) derived from the unsaturated carboxylic acid ester

Is a fluorine-containing polymer particle having a fluorine-containing polymer.

[Application example 2]

In the binder composition for electrodes of Application Example 1,

When the fluorine-containing polymer particles are subjected to differential scanning calorimetry (DSC) according to JIS K7121, only one endothermic peak in the temperature range of -50 to + 250 占 폚 can be observed.

[Application Example 3]

In the binder composition for electrodes of Application Example 2,

The endothermic peak can be observed in a temperature range of -30 to + 30 占 폚.

[Application example 4]

In the binder composition for electrodes of Application Example 1,

The concentration of the compound (B) in the binder composition may be 50 to 1,500 ppm.

[Application Example 5]

In the binder composition for electrodes of Application Example 1,

The compound (B) may be at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2).

≪ Formula 1 >

(Wherein R ¹ represents a hydrogen atom or a hydrocarbon group, and R ² and R ³ each represent a hydrogen atom, a halogen atom or a hydrocarbon group)

(2)

(Wherein R ⁴ represents a hydrogen atom or a hydrocarbon group, R ⁵ independently represents a hydrogen atom or an organic group, and n represents an integer of 0 to 4)

[Application Example 6]

In the binder composition for electrodes of Application Example 1,

The number average particle diameter of the fluorine-containing polymer particles may be 50 to 400 nm.

[Application Example 7]

The electrode binder composition according to the second aspect of the present invention,

A binder composition for producing an electrode for use in a power storage device,

(A), an isothiazoline compound (B) and a liquid medium (C)

The polymer (A)

The repeating unit (Mc) derived from the conjugated diene compound,

A repeating unit (Md) derived from an aromatic vinyl compound,

(Me) derived from a (meth) acrylate compound,

The repeating unit (Mf) derived from the unsaturated carboxylic acid

Based polymer particles,

And the concentration of the compound (B) in the binder composition is 50 ppm or more and less than 200 ppm.

[Application Example 8]

In the binder composition for electrodes of Application Example 7,

When the diene polymer particles are subjected to differential scanning calorimetry (DSC) according to JIS K7121, only one endothermic peak in the temperature range of -40 to +20 占 폚 can be observed.

[Application Example 9]

In the binder composition for electrodes of Application Example 7,

The compound (B) may be at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2).

≪ Formula 1 >

(Wherein R ¹ represents a hydrogen atom or a hydrocarbon group, and R ² and R ³ each represent a hydrogen atom, a halogen atom or a hydrocarbon group)

(2)

(Wherein R ⁴ represents a hydrogen atom or a hydrocarbon group, R ⁵ independently represents a hydrogen atom or an organic group, and n represents an integer of 0 to 4)

[Application Example 10]

In the binder composition for electrodes of Application Example 7,

The number average particle size of the diene polymer particles may be 50 to 400 nm.

[Application Example 11]

In the electrode slurry according to the third aspect of the present invention,

And a binder composition for electrodes of any one of Application Examples 1 to 10 and an electrode active material.

[Application Example 12]

In the electrode according to the fourth aspect of the present invention,

And a layer formed by coating and drying the electrode slurry of Application Example 11 on the surface of the current collector.

[Application Example 13]

In a power storage device according to a fifth aspect of the present invention,

And the electrode of Application Example 12 is provided.

According to the electrode binder composition, an electrode having excellent storage stability over a long period of time and having excellent adhesion and charge / discharge characteristics even when stored over a long period of time can be produced. The electrical storage device including the electrode manufactured using the electrode binder composition has a very good charge / discharge rate characteristic, which is one of the electrical characteristics.

1 is a DSC chart of the polymer particles obtained in Example 3. Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail. It is to be understood that the present invention is not limited to the embodiments described below, but may be modified in various manners without departing from the scope of the present invention. In the present specification, "(meth) acrylic acid" is a concept covering both of "acrylic acid" and "methacrylic acid". The term " (meth) acrylate " is a concept covering both of " acrylate " and " methacrylate ".

1. Binder composition for electrodes

The binder composition for electrodes according to one embodiment of the present invention contains a polymer (A), an isothiazoline compound (B) and a liquid medium (C) as a binder composition for producing an electrode used in a power storage device. Hereinafter, each component included in the electrode binder composition according to the present embodiment will be described in detail.

1.1. Polymer (A)

The polymer (A) contained in the binder composition for electrodes according to the present embodiment is preferably a latex phase dispersed as particles in the liquid medium (C). When the binder composition for electrodes is in a latex state, it is preferable that the stability of the electrode slurry produced by mixing with the electrode active material is improved and the applicability of the electrode slurry to the collector is improved. Hereinafter, the polymer (A) dispersed as particles in the liquid medium (C) is referred to as " polymer particle (A) ".

As the polymer particles (A), commercially available latex may be used. When the electrode binder composition according to the present embodiment is used for producing the positive electrode, the polymer particles (A) are preferably the fluorine-containing polymer particles described below.

The fluorine-containing polymer particles have a repeating unit (Ma) derived from a fluorine-containing ethylenic monomer and a repeating unit (Mb) derived from an unsaturated carboxylic acid ester. The fluorine-containing polymer particles are obtained by polymerizing a polymer (Aa) having a repeating unit (Ma) derived from a fluorine-containing ethylenic monomer and a polymer (Ab) having a repeating unit (Mb) derived from an unsaturated carboxylic acid ester It is preferable that the particles are spherical particles.

The term " polymeric alloy " &Quot; generic name of a multicomponent polymer obtained by mixing or chemical bonding of two or more polymers ", " polymer blend obtained by physically mixing a heteropolymer, " Block and graft copolymers, polymer complexes in which the heteropolymers are assembled by intermolecular force, and IPN (Interpenetrating Polymer Network) in which the heteropolymers are intertwined ". However, the polymer alloy particles that can be contained in the binder composition for electrodes of the present invention include those referred to as " polymeric alloys in which the heteropolymer component is not bonded by a covalent bond " Particle.

When the fluorine-containing polymer particles are polymer particle, the polymer (Aa) having the repeating unit (Ma) derived from the fluorine-containing ethylenic monomer aggregates hard segments of the crystalline resin, F-C. ≪ / RTI > Therefore, when the polymer (Aa) is used alone as the binder resin, its oxidation resistance is good, but the adhesiveness and flexibility are insufficient. On the other hand, the polymer (Ab) having a repeating unit (Mb) derived from an unsaturated carboxylic acid ester has excellent adhesion and flexibility but is low in oxidation resistance. Therefore, when this is used alone as a binder resin, charge and discharge are repeated So that the charge / discharge characteristics can not be obtained.

However, by using the polymer alloy particles having the polymer (Aa) and the polymer (Ab), oxidation resistance and adhesion can be simultaneously exhibited, and a positive electrode exhibiting better charge / discharge characteristics can be produced. Further, when the polymer particle has the polymer (Aa) and the polymer (Ab), the oxidation resistance can be further improved.

On the other hand, when the electrode binder composition according to the present embodiment is used for producing the negative electrode, the polymer particles (A) are preferably diene-based polymer particles. The diene polymer particles are obtained by polymerizing a repeating unit (Mc) derived from a conjugated diene compound, a repeating unit (Md) derived from an aromatic vinyl compound, a repeating unit (Me) derived from a (meth) acrylate compound, (Mf) derived from a carboxylic acid.

Hereinafter, the fluorine-containing polymer particles and the diene polymer particles will be described in this order.

1.1.1. Fluorine-containing polymer particles

1.1.1.1. The repeating unit (Ma) derived from the fluorine-containing ethylenic monomer

As described above, the fluorine-containing polymer particles used in the present embodiment have a repeating unit (Ma) derived from a fluorine-containing ethylenic monomer. Examples of the fluorine-containing ethylenic monomer include an olefin compound having a fluorine atom and a (meth) acrylate compound having a fluorine atom. Examples of the fluorine atom-containing olefin compound include vinylidene fluoride, ethylene tetrafluoride, propylene hexafluoride, ethylene chloride trifluoride, and perfluoroalkyl vinyl ether. Examples of the (meth) acrylate compound having a fluorine atom include compounds represented by the following formula (3), (meth) acrylic acid [4 [1 -trifluoromethyl-2,2-bis [bis ) Fluoromethyl] ethynyloxy] benzooxy] 2-hydroxypropyl and the like.

(3)

(Wherein R ⁶ is a hydrogen atom or a methyl group, and R ⁷ is a hydrocarbon group having 1 to 18 carbon atoms and containing a fluorine atom)

Examples of R ⁷ in the general formula (3) include fluorinated alkyl groups having 1 to 12 carbon atoms, fluorinated aryl groups having 6 to 16 carbon atoms, fluorinated aralkyl groups having 7 to 18 carbon atoms, and the like. Alkyl groups are preferred. Preferred examples of R ⁷ in the formula (3) include, for example, 2,2,2-trifluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3 , 3-hexafluoropropan-2-yl group,? - (perfluorooctyl) ethyl group, 2,2,3,3-tetrafluoropropyl group, 2,2,3,4,4,4-hexafluoro Perfluoro-1-nonyl group, 1H, 1H, 11H-perfluoro decyl group, perfluorooctyl group, etc., .

As the fluorine-containing ethylenic monomer, an olefin compound having a fluorine atom is preferable, and it is more preferable that it is at least one selected from the group consisting of vinylidene fluoride, ethylene tetrafluoride, and propylene hexafluoride. The above-mentioned fluorine-containing ethylenic monomers may be used singly or in combination of two or more kinds.

In general, the fluorinated polymer component having a repeating unit (Ma) derived from a fluorine-containing ethylenic monomer is considered to have good oxidation resistance and has been conventionally used for a positive electrode binder composition. However, such a fluorinated polymer component has poor adhesion lost. Therefore, in the prior art, studies have been made to improve the adhesion of the fluorinated polymer by various modifications. However, for example, attempts to improve the adhesion by introducing a functional group into the polymer chain require precise control of the synthesis conditions of the polymer, and it is difficult to achieve the object.

In the present invention, by using the fluorine-containing polymer particles having the repeating unit (Ma) derived from the fluorine-containing ethylenic monomer and the repeating unit (Mb) derived from the unsaturated carboxylic acid ester, Thereby making it possible to exhibit adhesion. The polymer (Aa) having a repeating unit (Ma) derived from a fluorine-containing ethylenic monomer and the polymer (Ab) having a repeating unit (Mb) derived from an unsaturated carboxylic acid ester as the fluorine-containing polymer particles By using the polymer particle, the adhesion can be expressed more effectively without deteriorating the oxidation resistance.

When the fluorine-containing polymer particles are polymer particle particles, the polymer (Aa) may have only the repeating unit (Ma) derived from the fluorine-containing ethylenic monomer, or may have the repeating unit (Ma) other than the fluorine- May have a repeating unit derived from another copolymerizable unsaturated monomer. Examples of such other unsaturated monomers include alkyl esters of unsaturated carboxylic acids, cycloalkyl esters of unsaturated carboxylic acids, hydrophilic monomers, crosslinkable monomers,? -Olefins, compounds having a hydroxyl group (provided that the hydrophilic monomers and crosslinkable Monomers, and the like), and the like, and at least one selected from these may be used.

Examples of the alkyl ester of the unsaturated carboxylic acid include (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i- (Meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl Nonyl, decyl (meth) acrylate and the like; Examples of the cycloalkyl ester of the unsaturated carboxylic acid include (meth) acryloyl cyclohexyl and the like, and at least one selected from the above can be used.

Examples of the hydrophilic monomers include unsaturated carboxylic acids, hydroxyalkyl esters of unsaturated carboxylic acids, polyhydric alcohol esters of unsaturated carboxylic acids, crosslinkable monomers,?,? -Unsaturated nitrile compounds, and compounds having hydroxyl groups. . Examples of the unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and the like; Examples of the hydroxyalkyl ester of the unsaturated carboxylic acid include hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, and the like; Examples of the polyhydric alcohol ester of the unsaturated carboxylic acid include (meth) acrylic acid ethylene glycol and the like; Examples of the crosslinkable monomer include di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylol propane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa of; Examples of the?,? - unsaturated nitrile compound include acrylonitrile, methacrylonitrile,? -Chloroacrylonitrile,? -Ethylacrylonitrile, vinylidene cyanide and the like; Examples of the compound having a hydroxyl group include p-hydroxystyrene and the like, and at least one selected from them can be used.

Since the polymer (Aa) has a constitutional unit derived from an unsaturated carboxylic acid among the above, the dispersion stability of the electrode slurry used in producing the electrode active material layer is improved, so that the electrode active material and the fluorine- A homogeneous layer of the electrode active material in which the polymer particles are not locally localized can be produced. As a result, the electrode active material layer becomes uniform in terms of strength and electrical conductivity, and the electrode active material layer is locally peeled off from the current collector, or the electrode active material or binder is localized, It is preferable in that deterioration can be effectively suppressed.

The content of the repeating unit (Ma) derived from the fluorine-containing ethylenic monomer in the polymer (Aa) is preferably 80% by mass or more, more preferably 90% by mass or more relative to the total mass of the polymer (Aa) to be.

When the polymer (Aa) contains a repeating unit derived from vinylidene fluoride, the content thereof is preferably from 50 to 99% by mass, and more preferably from 80 to 98% by mass. When the polymer (Aa) contains a repeating unit derived from ethylene tetrafluoride, the content thereof is preferably 1 to 50% by mass, and more preferably 2 to 20% by mass. When the polymer (Aa) contains a repeating unit derived from propylene hexafluoride, the content thereof is preferably 1 to 50% by mass, and more preferably 2 to 20% by mass.

The polymer (Aa) can be easily prepared by emulsion polymerization of the above-mentioned fluorine-containing ethylenic monomer, and optionally other unsaturated monomers according to a known method.

1.1.1.2. The repeating unit (Mb) derived from the unsaturated carboxylic acid ester

As described above, the fluorine-containing polymer particles used in the present embodiment have a repeating unit (Mb) derived from an unsaturated carboxylic acid ester. Generally, a polymer having a repeating unit (Mb) derived from an unsaturated carboxylic acid ester is considered to have poor adhesion but poor oxidation resistance and has not been used for a positive electrode conventionally. However, the present invention uses a fluorine-containing polymer particle having a repeating unit (Ma) derived from a fluorine-containing ethylenic monomer and a repeating unit (Mb) derived from an unsaturated carboxylic acid ester, It has succeeded in manifesting oxidation resistance.

The unsaturated carboxylic acid ester is preferably a (meth) acrylate compound. Specific examples of such (meth) acrylate compounds include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i- (Meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl, nonyl (meth) acrylate, decyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (Trimethylolpropane) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, allyl methacrylate and ethylene di , Selected from these It may be more than one kind. Among these, at least one selected from methyl (meth) acrylate, ethyl (meth) acrylate and 2-ethylhexyl (meth) acrylate is preferable, and methyl (meth) acrylate is particularly preferable.

When the fluorine-containing polymer particles are polymer particles, the polymer (Ab) may be a polymer having only a repeating unit (Mb) derived from an unsaturated carboxylic acid ester or a polymer having a repeating unit (Mb ), Other constituent units derived from other unsaturated monomers copolymerizable therewith may be used.

The content of the repeating unit (Mb) derived from the unsaturated carboxylic acid ester in the polymer (Ab) is preferably 65% by mass or more, more preferably 75% by mass or more with respect to the total mass of the polymer (Ab) to be.

Examples of the other unsaturated monomer include an?,? - unsaturated nitrile compound such as acrylonitrile, methacrylonitrile,? -Chloroacrylonitrile,? -Ethyl acrylonitrile and vinylidene cyanide; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid; Conjugated diene compounds such as 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and 2-chloro-1,3-butadiene; Aromatic vinyl compounds such as styrene,? -Methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, and divinylbenzene, and other unsaturated monomers, and the like.

1.1.1.3. Preparation of fluorine-containing polymer particles

The method of synthesizing the fluorine-containing polymer particles is not particularly limited as long as the above-described constitution is adopted. For example, the fluorine-containing polymer particles can be easily synthesized by a known emulsion polymerization process or by appropriately combining them.

For example, first, a polymer (Aa) having a repeating unit (Ma) derived from a fluorine-containing ethylenic monomer is synthesized by a known method. Next, a monomer for constituting the polymer (Ab) is added to the polymer (Aa), the monomer is sufficiently absorbed into the network structure of the polymer particle containing the polymer (Aa), and then the monomer The fluorine-containing polymer particles can be easily produced by a method of polymerizing the monomer (Ab) obtained by polymerizing the monomer. Further, in the case of producing the polymer alloy particles by such a method, it is essential to sufficiently absorb the monomer of the polymer (Ab) to the polymer (Aa). In the case where the absorption temperature is excessively low or the absorption time is too short, only a part of the core shell particle or the surface layer becomes an IPN-type structure, and the fluorine-containing polymer particles in the present invention can not be obtained in many cases. However, if the absorption temperature is excessively high, the pressure of the polymerization system becomes excessively high, which is disadvantageous from the viewpoint of handling and reaction control of the reaction system. Even if the absorption time is excessively long, more advantageous results are not obtained.

In view of the above, the absorption temperature is preferably 30 to 100 DEG C, more preferably 40 to 80 DEG C, and the absorption time is preferably 1 to 12 hours, more preferably 2 to 8 hours More preferable. At this time, when the absorption temperature is low, the absorption time is preferably long, and when the absorption temperature is high, a short absorption time is sufficient. It is appropriate that the value obtained by multiplying the absorption temperature (占 폚) by the absorption time (h) is in the range of 120 to 300 (占 h), preferably 150 to 250 (占 h).

The operation of absorbing the monomer of the polymer (Ab) into the network structure of the polymer (Aa) is preferably carried out in a known solvent used for emulsion polymerization, for example, in water.

The content of the polymer (Aa) in the fluorine-containing polymer particles is preferably 1 to 60 parts by mass, more preferably 5 to 55 parts by mass, further preferably 10 to 50 parts by mass in 100 parts by mass of the fluorine-containing polymer particles , And particularly preferably from 20 to 40 parts by mass. When the fluorine-containing polymer particles contain the polymer (Aa) in the above-described range, the balance between the oxidation resistance and the adhesion becomes better.

The polymerization of the polymer (Aa) or the polymerization of the polymer (Ab) carried out after the absorption of the monomer into the polymer (Aa) is carried out in the presence of a known emulsifier (surfactant), polymerization An initiator, a molecular weight regulator, and the like.

Specific examples of the emulsifying agent include, for example, sulfuric acid ester salts of higher alcohols, alkylbenzenesulfonic acid salts, alkyldiphenyl ether disulfonic acid salts, aliphatic sulfonic acid salts, aliphatic carboxylic acid salts, dihydroabietic acid salts, naphthalenesulfonic acid- Anionic surfactants such as sulfuric acid ester salts of anionic surfactants; Alkyl esters of polyethylene glycol, alkylphenyl ethers of polyethylene glycol, alkyl ethers of polyethylene glycol and the like; Fluorine surfactants such as perfluorobutyl sulfonic acid salts, perfluoroalkyl group-containing phosphoric acid esters, perfluoroalkyl group-containing carboxylic acid salts and perfluoroalkylethylene oxide adducts, and the like, Or more can be used.

Specific examples of the polymerization initiator include water-soluble polymerization initiators such as lithium persulfate, potassium persulfate, sodium persulfate and ammonium persulfate; Benzoyl peroxide, t-butyl hydroperoxide, acetyl peroxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, azobisisobutyronitrile, 1 , 1'-azobis (cyclohexanecarbonitrile), and the like can be appropriately selected and used. Among them, potassium persulfate, sodium persulfate, cumene hydroperoxide or t-butyl hydroperoxide is preferably used. The ratio of the polymerization initiator to be used is not particularly limited, but is suitably set in consideration of the combination of the monomer composition, the pH of the polymerization reaction system, other additives, and the like.

Specific examples of the molecular weight modifier include alkylmercaptan such as n-hexylmercaptan, n-octylmercaptan, t-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, ; Xanthene compounds such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; Thiuram compounds such as terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide; Phenol compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; Allyl compounds such as allyl alcohol; Halogenated hydrocarbon compounds such as dichloromethane, dibromomethane and carbon tetrabromide; pentylphenyl ethane, acrolein, methacrolein, thioglycolic acid, thiomalic acid, 2-ethylhexyl methacrylate, and the like, as well as vinyl ether compounds such as? -benzyloxystyrene,? -benzyloxyacrylonitrile and? -Ethylhexyl thioglycolate,? -Methylstyrene dimer, and the like, and at least one selected from these may be used.

1.1.2. Diene-based polymer particles

1.1.2.1. The repeating unit (Mc) derived from the conjugated diene compound

By having the diene polymer particles have a repeating unit (Mc) derived from the conjugated diene compound, it is easy to produce a negative electrode binder composition excellent in viscoelasticity and strength. That is, when a polymer having a repeating unit derived from a conjugated diene compound is used, the polymer can have a strong binding ability. Since the rubber elasticity derived from the conjugated diene compound is imparted to the polymer, it is possible to follow changes in the volume shrinkage and expansion of the electrode. Accordingly, it is considered that the battery has improved durability to improve the coupling ability and further to maintain the charge / discharge characteristics for a long period of time.

Examples of the conjugated diene compound include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and 2-chloro-1,3-butadiene , And at least one selected from these. As the conjugated diene compound, 1,3-butadiene is particularly preferable.

The content of the repeating unit (Mc) derived from the conjugated diene compound is preferably 30 to 60 parts by mass, and more preferably 35 to 55 parts by mass, when the total repeating units are 100 parts by mass. When the content ratio of the repeating unit (Mc) is in the above range, it is possible to further improve the binding ability.

1.1.2.2. The repeating unit (Md) derived from an aromatic vinyl compound

By having the diene polymer particles have a repeating unit (Md) derived from an aromatic vinyl compound, affinity to the negative electrode slurry can be improved when the negative electrode slurry contains a conductivity-imparting agent.

Specific examples of the aromatic vinyl compound include styrene,? -Methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, divinylbenzene, and the like, and may be at least one selected from these. As the aromatic vinyl compound, styrene is particularly preferable among the above.

The content of the repeating unit (Md) derived from the aromatic vinyl compound is preferably 10 to 40 parts by mass, and more preferably 15 to 35 parts by mass, when the total repeating units are 100 parts by mass. When the content of the repeating unit (Md) is in the above range, the polymer particles have an appropriate binding ability to graphite used as the electrode active material. In addition, the obtained electrode active material layer has good flexibility and adhesion to the current collector.

1.1.2.3. The repeating unit (Me) derived from the (meth)

Since the diene polymer particles have the repeating unit (Me) derived from the (meth) acrylate compound, the affinity with the electrolytic solution becomes good, and the increase in the internal resistance due to the binding agent becoming the electric resistance component in the electric storage device is suppressed And at the same time, the deterioration of the coupling ability due to the excessive absorption of the electrolytic solution can be prevented.

Specific examples of such (meth) acrylate compounds include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i- (Meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl, nonyl (meth) acrylate, decyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (Trimethylolpropane) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, allyl methacrylate and ethylene di , Selected from these It may be more than one kind. Among these, at least one selected from methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hydroxymethyl (meth) acrylate and hydroxyethyl Methyl (meth) acrylate, hydroxymethyl (meth) acrylate and hydroxyethyl (meth) acrylate.

The content of the repeating unit (Me) derived from the (meth) acrylate compound is preferably from 5 to 40 parts by mass, more preferably from 6 to 30 parts by mass, based on 100 parts by mass of the total repeating units. When the content of the repeating unit (Me) is within the above range, the resulting diene polymer particles have an affinity with the electrolyte solution, so that the increase of the internal resistance due to the binding agent becoming an electrical resistance component in the electrical storage device is suppressed , It is possible to prevent deterioration of the coupling ability due to excessive absorption of the electrolytic solution.

1.1.2.4. The repeating unit (Mf) derived from the unsaturated carboxylic acid

Since the diene polymer particles have a repeating unit (Mf) derived from an unsaturated carboxylic acid, the storage stability of the electrode slurry using the binder composition for electrodes of the present invention is improved.

Specific examples of the unsaturated carboxylic acid include mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid, and may be at least one selected from these. Particularly, at least one selected from acrylic acid, methacrylic acid and itaconic acid is preferable.

The content of the repeating unit (Mf) derived from the unsaturated carboxylic acid is preferably 15 parts by mass or less, more preferably 0.3 to 10 parts by mass, based on 100 parts by mass of the total repeating units. When the content of the repeating unit (Mf) is in the above range, the dispersion stability of the diene-based polymer particles at the time of producing the electrode slurry is excellent, so that aggregates are hardly generated. In addition, it is possible to suppress the rise of the slurry viscosity over time.

1.1.2.5. Other repeat units

The diene polymer particles may have other repeating units than those described above. Examples of the repeating unit other than the above include repeating units derived from an?,? - unsaturated nitrile compound.

By having the diene polymer particles have a repeating unit derived from an?,? - unsaturated nitrile compound, the swelling property of the diene polymer particles with respect to the electrolytic solution can be further improved. That is, the presence of the nitrile group makes it easier for the solvent to enter the network structure including the polymer chain, so that the network interval is widened, so that the solvated lithium ions are easily moved through the network. Accordingly, it is considered that the diffusion property of lithium ions is improved, and as a result, the electrode resistance is lowered, and better charge / discharge characteristics can be realized.

Specific examples of the?,? - unsaturated nitrile compound include, for example, acrylonitrile, methacrylonitrile,? -chloroacrylonitrile,? -ethyl acrylonitrile and vinylidene cyanide. It may be more than one kind. Of these, at least one selected from acrylonitrile and methacrylonitrile is preferable, and acrylonitrile is more preferable.

The content of the repeating unit derived from the?,? - unsaturated nitrile compound is preferably 35 parts by mass or less, more preferably 5 to 25 parts by mass, based on 100 parts by mass of the total repeating units. When the content of the repeating unit derived from the?,? - unsaturated nitrile compound is within the above range, the compatibility with the electrolytic solution to be used is excellent, the swelling rate is not excessively increased, and the battery characteristics can be improved.

Further, the diene polymer particles may further have a repeating unit derived from the compound shown below. Examples of such a compound include fluorine-containing compounds having ethylenic unsaturated bonds such as vinylidene fluoride, ethylene tetrafluoride, and propylene hexafluoride; Alkyl amides of ethylenically unsaturated carboxylic acids such as (meth) acrylamide and N-methylol acrylamide; Carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate; Acid anhydrides of ethylenically unsaturated dicarboxylic acids; Aminoalkylamides of ethylenically unsaturated carboxylic acids such as aminoethyl acrylamide, dimethylaminomethylacrylamide and methylaminopropylmethacrylamide, and the like, and they may be at least one selected from these.

1.1.2.6. Preparation of diene-based polymer particles

The method of synthesizing the diene polymer particles is not particularly limited, but can be easily produced, for example, by the following two-step emulsion polymerization process.

1.1.2.6.1. The first polymerization step

Examples of the monomer component (I) used in the first emulsion polymerization step include non-carboxylate (meth) acrylates such as an?,? - unsaturated nitrile compound, conjugated diene compound, aromatic vinyl compound and (meth) A monomer and a carboxylic acid monomer such as an unsaturated carboxylic acid are contained. The content of the non-carboxylic acid monomer contained in the monomer component (I) is preferably 80 to 92 parts by mass, more preferably 82 to 92 parts by mass, in 100 parts by mass of the total amount of the non-carboxylic acid monomer and the carboxylic acid monomer desirable. When the content of the non-carboxylic acid monomer is within the above range, aggregation is less likely to occur because the dispersion stability of the polymer particles is excellent at the time of producing the electrode slurry. In addition, it is possible to suppress the rise of the slurry viscosity over time.

In the monomer component (I), the content of the (meth) acrylate compound in the non-carboxylic acid monomer is preferably from 10 to 30 mass%. When the content of the (meth) acrylate compound is within the above range, the dispersion stability of the polymer particles at the time of preparing the electrode slurry is excellent, so that the aggregation is less likely to occur. In addition, the obtained polymer particles have an affinity with the electrolytic solution becomes appropriate, and it is possible to prevent the deterioration of the binding ability due to the excessive absorption of the electrolytic solution.

In the monomer component (I), the content ratio of the conjugated diene compound in the non-carboxylic acid monomer is preferably from 10 to 60 mass%, and the content of the aromatic vinyl compound is preferably from 20 to 60 mass%. The proportion of itaconic acid in the carboxylic acid-based monomer is preferably 50 to 85% by mass.

1.1.2.6.2. In the second stage polymerization step

Examples of the monomer component (II) used in the emulsion polymerization step in the second stage include non-carboxylic acid monomers such as an?,? - unsaturated nitrile compound, conjugated diene compound, aromatic vinyl compound and (meth) Carboxylic acid monomers such as unsaturated carboxylic acids are contained. The content of the non-carboxylic acid monomer contained in the monomer component (II) is preferably 94 to 99 mass% of the total of 100 mass% of the non-carboxylic acid monomer and the carboxylic acid monomer. When the content of the non-carboxylic acid monomer is within the above range, aggregation is less likely to occur because the dispersion stability of the polymer particles is excellent at the time of producing the electrode slurry. In addition, it is possible to suppress the rise of the slurry viscosity over time.

In the monomer component (II), the content of the (meth) acrylate compound in the non-carboxylic acid monomer is preferably not more than 17% by mass. When the content of the (meth) acrylate compound is within the above range, the obtained polymer particles have an affinity with the electrolyte appropriately, and the deterioration of the binding ability due to the excessive absorption of the electrolyte can be prevented.

The mass ratio ((I) / (II) ratio) of the monomer component (I) to the monomer component (II) in the polymer constituent monomer is preferably 0.05 to 0.5, more preferably 0.1 to 0.4. When the ratio of (I) / (II) is in the above range, aggregation is less likely to occur because the dispersion stability of the polymer particles is excellent at the time of preparing the electrode slurry. In addition, it is possible to suppress the rise of the slurry viscosity over time.

1.1.2.6.3. Emulsion polymerization

The emulsion polymerization process is carried out in the presence of an emulsifier, a polymerization initiator and a molecular weight modifier in an aqueous medium. Hereinafter, each material used in the emulsion polymerization process will be described.

Specific examples of the emulsifying agent include, for example, sulfuric acid ester salts of higher alcohols, alkylbenzenesulfonic acid salts, alkyldiphenyl ether disulfonic acid salts, aliphatic sulfonic acid salts, aliphatic carboxylic acid salts, dihydroabietic acid salts, naphthalenesulfonic acid- Anionic surfactants such as sulfuric acid ester salts of anionic surfactants; Alkyl esters of polyethylene glycol, alkylphenyl ethers of polyethylene glycol, alkyl ethers of polyethylene glycol and the like; Fluorine surfactants such as perfluorobutyl sulfonic acid salts, perfluoroalkyl group-containing phosphoric acid esters, perfluoroalkyl group-containing carboxylic acid salts and perfluoroalkylethylene oxide adducts, and the like, Or more can be used.

Specific examples of the polymerization initiator include water-soluble polymerization initiators such as lithium persulfate, potassium persulfate, sodium persulfate and ammonium persulfate; Benzoyl peroxide, t-butyl hydroperoxide, acetyl peroxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, azobisisobutyronitrile, 1 , 1'-azobis (cyclohexanecarbonitrile), and the like can be appropriately selected and used. Among them, potassium persulfate, sodium persulfate, cumene hydroperoxide or t-butyl hydroperoxide is preferably used. The ratio of the polymerization initiator to be used is not particularly limited, but is suitably set in consideration of the combination of the monomer composition, the pH of the polymerization reaction system, other additives, and the like.

Specific examples of the molecular weight modifier include alkylmercaptan such as n-hexylmercaptan, n-octylmercaptan, t-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, ; Xanthene compounds such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; Thiuram compounds such as terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide; Phenol compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; Allyl compounds such as allyl alcohol; Halogenated hydrocarbon compounds such as dichloromethane, dibromomethane and carbon tetrabromide; pentylphenyl ethane, acrolein, methacrolein, thioglycolic acid, thiomalic acid, 2-benzyloxyacrylamide, and the like, as well as vinyl ether compounds such as? -benzyloxystyrene,? -benzyloxyacrylonitrile,? -benzyloxyacrylamide, -Ethylhexyl thioglycolate,? -Methylstyrene dimer, and the like, and at least one selected from these may be used.

1.1.2.6.4. Conditions for emulsion polymerization

The first emulsion polymerization step is preferably carried out under the conditions of a polymerization temperature of 40 to 80 캜 and a polymerization time of 2 to 4 hours. In the first emulsion polymerization step, the polymerization conversion rate is preferably 50% or more, more preferably 60% or more. The emulsion polymerization step in the second stage is preferably carried out under the conditions of a polymerization temperature of 40 to 80 캜 and a polymerization time of 2 to 6 hours.

After the completion of the emulsion polymerization, it is preferable to neutralize the dispersion by adding a neutralizing agent so that the pH of the dispersion becomes about 5 to 10. The neutralizing agent to be used is not particularly limited, but usually includes metal hydroxides such as sodium hydroxide and potassium hydroxide, and ammonia. By adjusting the pH of the dispersion to be in the range of 5 to 10, the dispersion stability of the dispersion becomes good, preferably 6 to 9, and more preferably 7 to 8.5. When the total solid content concentration in the emulsion polymerization process is 50 mass% or less, the reaction can proceed with good dispersion stability, preferably 45 mass% or less, and more preferably 40 mass% or less. Further, after the neutralization treatment is carried out, it is possible to obtain a high-solid content while improving the stability of the particles.

1.1.3. The physical properties of the polymer particles (A)

1.1.3.1. Tetrahydrofuran (THF) insoluble matter

The THF-insoluble matter of the polymer particles (A) is preferably 80% or more, more preferably 90% or more. It is assumed that the THF insoluble matter is almost proportional to the insoluble amount for the electrolyte used in the electrical storage device. Therefore, if the THF-insoluble content is in the above-mentioned range, it can be inferred that the elution of the polymer (A) into the electrolytic solution can be suppressed even when charging and discharging are repeated over a long period of time by producing the battery device.

1.1.3.2. Transition temperature

When the polymer particles (A) are fluorine-containing polymer particles, it is preferable that they have only one endothermic peak in a temperature range of -50 to 250 占 폚 as measured by differential scanning calorimetry (DSC) according to JIS K7121 Do. It is more preferable that the temperature of the endothermic peak is in the range of -30 to + 30 占 폚. When the temperature of only one endothermic peak of the fluorine-containing polymer particles is in the range of -30 to + 30 占 폚, the particles can give better flexibility and tackiness to the electrode active material layer, It is preferable in that it can be further improved.

When the polymer (Aa) is present alone, it generally has an endothermic peak (melting temperature) at -50 to 250 ° C. Further, the polymer (Ab) generally has an endothermic peak (glass transition temperature) different from that of the polymer (Aa). Therefore, when the polymer (Aa) and the polymer (Ab) in the particle exist in phase-separated form, for example, as a core-shell structure, two endothermic peaks will be observed at -50 to 250 ° C. However, when there is only one endothermic peak at -50 to 250 ° C, it means that the polymer (Aa) and the polymer (Ab) exist without phase separation, and it can be assumed that the particles are polymeric alloy particles have.

When the polymer particles (A) are the diene-based polymer particles, it is preferable that they have only one endothermic peak in the temperature range of -40 to +20 占 폚 as measured by differential scanning calorimetry (DSC) according to JIS K7121 Do. The temperature of this endothermic peak is more preferably in the range of -30 to +20 占 폚, and more preferably -25 to +10 占 폚. When the temperature of only one endothermic peak of the diene polymer particles is in the above-mentioned range, it is preferable in that the better flexibility and tackiness can be imparted to the electrode active material layer and thus the adhesion can be further improved.

1.1.3.3. Number average particle diameter

The number average particle size of the polymer particles (A) is preferably in the range of 50 to 400 nm, and more preferably in the range of 100 to 250 nm. When the number average particle size of the polymer particles (A) is in the above range, the polymer particles (A) can be sufficiently adsorbed on the surface of the electrode active material, so that the polymer particles (A) . As a result, migration of only either of the two particles can be suppressed, and deterioration of electrical characteristics can be suppressed.

The number average particle size of the polymer particles (A) refers to a particle size distribution measured by a particle size distribution measuring apparatus using the light scattering method as a measurement principle, and the cumulative number of particles when accumulating particles from small particles is 50% Is the value of the particle diameter (D50). Examples of such particle size distribution measuring apparatuses include Coulter LS230, LS100, and LS13 320 (manufactured by Beckman Coulter. Inc.) And FPAR-1000 (manufactured by Otsuka Denshi Kabushiki Kaisha) have. These particle size distribution measuring apparatuses are not intended to evaluate only the primary particles of the polymer particles, and secondary particles formed by agglomeration of the primary particles can also be evaluated. Therefore, the particle size distribution measured by these particle size distribution measuring apparatuses can be an index of the dispersion state of the polymer particles contained in the electrode slurry. The number average particle size of the polymer particles (A) can also be measured by centrifuging the electrode slurry to precipitate the electrode active material, and then measuring the supernatant thereof with the particle size distribution measuring apparatus described above.

1.2. The isothiazoline compound (B)

The electrode binder composition according to this embodiment contains an isothiazoline compound (B). By adding the isothiazoline compound (B) to the electrode binder composition, the isothiazoline compound (B) acts as an antiseptic agent, and when the electrode binder composition is stored, bacteria and fungi grow and foreign matter is generated Can be suppressed. Further, deterioration of the binder at the time of charging / discharging of the power storage device is suppressed, so that the lowering of the charge / discharge characteristics of the power storage device can be suppressed.

The mechanism of the effect of suppressing deterioration of the binder at the time of charging and discharging of the electrical storage device is not clear, but is considered as follows. Since the affinity of the isothiazoline compound (B) with the polymer particle is good, even when the electrode active material layer is immersed in the electrolytic solution, the isothiazoline compound (B) is adsorbed to a polymer functioning as a binder So that it is considered that the electrode active material layer is hardly eluted into the electrolyte solution. It is presumed that the isothiazoline-based compound (B) is retained in the polymer so that deterioration of the polymer functioning as the binder by the electrolyte is suppressed, and that the deterioration of the electrolyte itself is suppressed, and as a result, the charge-discharge characteristics are not deteriorated.

In addition, when a new component is added to a dispersion of polymer particles such as latex in general, the new component becomes a trigger, and aggregation tends to occur. Incidentally, since the isothiazoline compound (B) has little influence on the dispersibility of the polymer particles, the occurrence of aggregates can be suppressed. Therefore, when the electrode active material is mixed with the electrode binder composition of the present invention to prepare an electrode slurry, aggregation of the polymer particles and the electrode active material can be suppressed because no trigger component exists. Therefore, it is possible to fabricate an electrode having a uniform electrode active material layer formed on the surface of the current collector, so that the charge / discharge characteristics of the power storage device are expected to be good.

It is also considered that the addition of the isothiazoline compound (B) to the electrode binder composition can improve the fluidity of the electrode slurry. As a result, the electrode active material layer having a more uniform thickness can be formed. As a result, even when charging / discharging is performed at a high rate, a voltage is uniformly applied to the entire surface of the electrode active material layer, Stable charging and discharging characteristics can be exhibited.

When the polymer particles (A) contained in the electrode binder composition are fluorine-containing polymer particles, the concentration of the isothiazoline compound (B) in the electrode binder composition is preferably 50 to 1,500 ppm, more preferably 50 to 1,200 ppm , More preferably from 50 to 1,000 ppm. When the concentration of the isothiazoline compound (B) in the electrode binder composition is within the above range, the storage stability over the long term of the electrode binder composition is improved, and the electrode slurry prepared using the composition is also applied to the current collector The power storage device having the electrode exhibits good charge / discharge characteristics.

If the concentration of the component (B) is less than the above-mentioned range, the above-mentioned effects can not be sufficiently exhibited, and in particular, a battery device which exhibits good charge / discharge characteristics when stored for a long period of time can not be produced. If the concentration of the component (B) exceeds the above range, a large amount of the component (B) is adsorbed on the surface of the polymer particles, and the bonding ability of the polymer particles is lowered, so that the adhesion ability between the current collector and the electrode active material layer is impaired There is a case.

When the polymer particles (A) contained in the electrode binder composition are diene-based polymer particles, the concentration of the isothiazoline compound (B) in the electrode binder composition should be 50 ppm or more and less than 200 ppm, ppm or less. When the concentration of the isothiazoline compound (B) in the electrode binder composition is within the above range, the storage stability over the long term of the electrode binder composition is improved, and the electrode slurry prepared using the composition is also applied to the current collector The electrical storage device having the manufactured electrode exhibits good charge / discharge characteristics. When the concentration of the isothiazoline compound (B) in the electrode binder composition is outside the above range, the charge and discharge characteristics of the battery device manufactured using the binder composition for electrode immediately after preparation are good, , The charging and discharging characteristics of the electrical storage device fabricated using the electrode binder composition stored for 5 months were found to be poor.

This reason is considered as follows. If the concentration of the isothiazoline-based compound (B) is less than 50 ppm, the storage stability can not be ensured over a long period of time because the content is insufficient. Thus, it is considered impossible to produce a battery device exhibiting good charge-discharge characteristics. On the other hand, if the concentration of the isothiazoline compound (B) is 200 ppm or more, it is considered that the diene polymer particles tend to aggregate because of the high affinity between the diene polymer particles and the isothiazoline compound do. Therefore, when the concentration of the isothiazoline compound (B) exceeds the above range, the electrode manufactured using the binder composition stored for a long period can not exhibit initial charging / discharging characteristics due to foreign matters such as aggregated particles I think. When the concentration of the isothiazoline compound (B) is 200 ppm or more, a large amount of the isothiazoline compound (B) is adsorbed on the surface of the diene polymer particles and the binding ability of the diene polymer particles is lowered. The adhesion ability of the entire electrode active material layer may be impaired.

The isothiazoline compound (B) contained in the electrode binder composition according to the present embodiment is not particularly limited as long as it is a compound having an isothiazoline skeleton. Specifically, a compound represented by the following formula (1) And compounds that are displayed.

≪ Formula 1 >

In the general formula (1), R ¹ represents a hydrogen atom or a hydrocarbon group, and R ² and R ³ each represent a hydrogen atom, a halogen atom or a hydrocarbon group. When R ¹ , R ² , and R ³ are hydrocarbon groups, they may have a straight chain or straight chain carbon skeleton such as a branched chain, or may have a cyclic carbon skeleton. The number of carbon atoms of the hydrocarbon group is preferably 1 to 12, more preferably 1 to 10, and particularly preferably 1 to 8. Specific examples of such hydrocarbon groups include methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, octyl and 2-ethylhexyl groups.

(2)

In the general formula (2), R ⁴ is a hydrogen atom or a hydrocarbon group, and each R ⁵ independently represents a hydrogen atom or an organic group. When R ⁴ is a hydrocarbon group, it may be the same hydrocarbon group as the hydrocarbon group described in the above formula (1). When R ⁵ is an organic group, the organic group includes an aliphatic group or an aromatic group, which is an alkyl group or a cycloalkyl group, and is preferably an aliphatic group. The alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 10 carbon atoms, and particularly preferably 1 to 8 carbon atoms. These alkyl groups and cycloalkyl groups may have substituents such as a halogen atom, an alkoxyl group, a dialkylamino group, an acyl group, and an alkoxycarbonyl group. Specific examples of the aliphatic group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, a cyclohexyl group, an octyl group and a 2-ethylhexyl group. In the general formula (2), n represents an integer of 0 to 4.

Specific examples of the component (B) contained in the electrode binder composition according to the present embodiment include 1,2-benzoisothiazolin-3-one, 2-methyl-4,5-trimethylene- Methyl-4-isothiazolin-3-one, N-butyl-1,2-benzisothiazoline-3 2-n-octyl-4-isothiazolin-3-one, and 2-n-octyl-4-isothiazolin- Or two or more of them may be used. Of these, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin- , 1,2-benzisothiazolin-3-one, and the like.

1.3. The liquid medium (C)

The binder composition for electrodes according to the present embodiment contains a liquid medium (C). The liquid medium (C) is preferably an aqueous medium containing water. The aqueous medium may contain a non-aqueous medium other than water. Examples of the non-aqueous medium include amide compounds, hydrocarbons, alcohols, ketones, esters, amine compounds, lactones, sulfoxides, and sulfone compounds, and at least one selected from these may be used. When the liquid medium (C) contains water and a non-aqueous medium other than water, it is preferable that 90% by mass or more of the total amount of the liquid medium (C) is 100% by mass, more preferably 98% Do. The use of the aqueous medium as the liquid medium (C) in the electrode binder composition according to the present embodiment lowers the degree of adverse effect on the environment and increases safety for the handling operator.

The content ratio of the non-aqueous medium contained in the aqueous medium is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably substantially no content with respect to 100 parts by mass of the aqueous medium. As used herein, the term " substantially not contained " means that the nonaqueous medium is not intentionally added as a liquid medium, and may include a nonaqueous medium inevitably incorporated when the binder composition for electrodes is produced.

1.4. Other additives

The binder composition for electrodes according to the present embodiment may contain additives other than the above-mentioned components (A), (B) and (C), if necessary. As such an additive, for example, a thickener may be mentioned. The binder composition for electrodes according to this embodiment contains a thickening agent, so that the coating properties and charging / discharging characteristics of the resulting battery device can be further improved.

Examples of such a thickening agent include cellulose compounds such as carboxymethylcellulose, methylcellulose, and hydroxypropylcellulose; An ammonium salt or an alkali metal salt of the cellulose compound; Polycarboxylic acids such as poly (meth) acrylic acid and modified poly (meth) acrylic acid; An alkali metal salt of the polycarboxylic acid; Polyvinyl alcohol-based (co) polymers such as polyvinyl alcohol, modified polyvinyl alcohol and ethylene-vinyl alcohol copolymer; And water-soluble polymers such as a saponification product of a copolymer of an unsaturated carboxylic acid such as (meth) acrylic acid, maleic acid and fumaric acid with a vinyl ester. Among these, particularly preferred thickening agents are alkali metal salts of carboxymethylcellulose and alkali metal salts of poly (meth) acrylic acid.

Commercially available products of these thickeners include, for example, alkali metal salts of carboxymethyl cellulose such as CMC1120, CMC1150, CMC2200, CMC2280, CMC2450 (manufactured by Daicel Chemical Industries, Ltd.).

When the binder composition for electrodes according to this embodiment contains a thickening agent, the proportion of the thickening agent to be used is preferably 5% by mass or less, more preferably 0.1 to 3% by mass based on the total solids content of the electrode binder composition.

2. Electrode slurry

As described above, the electrode slurry according to one embodiment of the present invention can be produced using the above-described binder composition for electrodes. The electrode slurry refers to a dispersion liquid used to form a layer of the electrode active material on the surface of the current collector by applying it to the surface of the current collector and then drying it. The electrode slurry according to the present embodiment contains the above-described binder composition for an electrode, an electrode active material and water. Hereinafter, the components included in the electrode slurry according to the present embodiment will be described in detail. However, since the binder composition for electrode is as described above, the explanation is omitted.

2.1. Electrode active material

The material constituting the electrode active material contained in the slurry for electrode according to the present embodiment is not particularly limited and a suitable material can be appropriately selected depending on the type of the intended power storage device.

For example, when a positive electrode of a lithium ion secondary battery is produced, it is preferably a lithium atom-containing oxide. As used herein, the term " oxide " means a compound or a salt containing oxygen and an element having a smaller electronegativity than that of oxygen, and includes not only metal oxides but also metal phosphates, nitrates, halogen oxoates, sulfonates Concept.

Examples of the lithium atom-containing oxide include a composite metal oxide represented by the following formula (4a) or (4b) and a lithium atom-containing oxide represented by the following formula (5) and having an olivinic crystal structure, and at least one selected from the group consisting of Is preferably used.

≪ Formula 4a &

Li _{1 + x} M ¹ _y M ² _z O ₂

<Formula 4b>

Li _{1 + x} M ¹ _y M ² _z O ₄

(4) wherein M ¹ is at least one metal atom selected from the group consisting of Co, Ni and Mn, M ² is at least one metal atom selected from the group consisting of Al and Sn, O X, y and z are numbers in the range of 0.10? X? 0, 4.00? Y? 0.85, and 2.00? Z?

&Lt; Formula 5 >

Li _{1- x} M ³ _x (XO ₄ )

(Wherein M ³ is at least one of metal ions selected from the group consisting of Mg, Ti, V, Nb, Ta, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, X is at least one species selected from the group consisting of Si, S, P and V, x is a number, and 0 < x <

The value of x in the formula (5) is selected so that the valence of the whole of the formula (5) is 0 according to the valences of M ³ and X.

Examples of the composite metal oxide represented by Formula 4a or 4b include LiCoO ₂ , LiNiO ₂ , LiNi _y Co _{1 - y} O ₂ (y = 0.01 to 0.99), LiMnO ₂ , LiMn ₂ O ₄ , LiCo _x Mn _y Ni _z O ₂ (x + y + z = 1), and at least one selected from these can be used. Among them, LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ and LiNi _{0 .33} Mn _{0 .33} Co _{0 .33} O ₂ have high electrode potential and high efficiency, so that a power storage device having high voltage and high energy density can be obtained . Li _{1 + x} M ¹ _y M ² _z O ₂ is particularly preferable in view of the fact that the Li diffusion rate in the solid is fast and the charge / discharge rate is excellent.

The lithium atom-containing oxide represented by Formula 5 and having an olivine crystal structure differs in electrode potential depending on the kind of the metal element M ³ . Therefore, by selecting the kind of the metal element M, the battery voltage can be set arbitrarily. Typical examples of the lithium atom-containing oxide having an olivine crystal structure include LiFePO ₄ , LiCoPO ₄ , Li _{0 .90} Ti _{0 .05} Nb _{0 .05} Fe _{0 .30} Co _{0 .30} Mn _{0 .30} PO ₄ , . Among them, LiFePO ₄ is particularly preferable since it is easy to obtain an iron compound as a raw material and is inexpensive. In addition, the compound in which the Fe ion in the above compound is substituted with the Co ion, the Ni ion or the Mn ion also has the same crystal structure as each of the above compounds, and therefore has the same effect as the electrode active material.

On the other hand, when a negative electrode of a lithium ion secondary battery is manufactured, for example, carbon may be used as an electrode active material (negative electrode active material). Specific examples of the carbon include a carbon material obtained by baking an organic high molecular compound such as a phenol resin, polyacrylonitrile, or cellulose; A carbon material obtained by baking coke or pitch; Artificial graphite; Natural graphite and the like.

In the case of producing an electric double layer capacitor electrode, for example, activated carbon, activated carbon fiber, silica, alumina or the like can be used as the electrode active material. When a lithium ion capacitor electrode is produced, a carbon material such as graphite, non-graphitized carbon, hard carbon or coke, or a polyacene-based organic semiconductor (PAS) can be used.

The number average particle diameter (Db) of the electrode active material is preferably in the range of 0.4 to 10 mu m in the positive electrode, and more preferably in the range of 0.5 to 7 mu m. In the negative electrode, the thickness is preferably in the range of 3 to 30 mu m, more preferably 5 to 25 mu m. When the number average particle size (Db) of the electrode active material is within the above range, the diffusion distance of lithium in the electrode active material is shortened, so that the resistance accompanying the lithium intercalation and deintercalation during charging and discharging can be reduced, The resulting charge / discharge characteristics are further improved. When the slurry for an electrode contains a conductive agent described later, the number average particle size (Db) of the electrode active material is within the above range, so that the contact area between the electrode active material and the conductive agent can be sufficiently secured, The electronic conductivity of the electrode is improved, and the electrode resistance is further lowered.

 Here, the number average particle size (Db) of the electrode active material means a particle size distribution measurement using a particle size distribution measuring apparatus using the laser diffraction method as a measurement principle, and the cumulative frequency of the number of particles (D50) of 50%. Examples of such a laser diffraction particle size distribution measuring apparatus include HORIBA LA-300 series and HORIBA LA-920 series (manufactured by Horiba Seisakusho Co., Ltd.). This particle size distribution measuring device is not intended to evaluate only the primary particles of the electrode active material, but also secondary particles formed by agglomerating primary particles. Therefore, the number-average particle diameter (Db) obtained by the particle size distribution measuring apparatus can be an index of the dispersion state of the electrode active material contained in the electrode slurry. The average particle diameter (Db) of the electrode active material can also be measured by centrifuging the electrode slurry to precipitate the electrode active material, removing the supernatant thereof, and measuring the precipitated electrode active material by the above-described method have.

2.2. Other ingredients

The electrode slurry may contain components other than the above-described components, if necessary. Examples of such components include a conductive agent, a non-aqueous medium, a thickener, and the like.

2.2.1. Challenge grant

Specific examples of the conductive agent include carbon and the like in the lithium ion secondary battery; In the nickel-hydrogen secondary battery, cobalt oxide is used for the positive electrode, and nickel powder, cobalt oxide, titanium oxide, carbon and the like are used for the negative electrode. Examples of the carbon in the both batteries include graphite, activated carbon, acetylene black, furnace black, graphite, carbon fiber, and fullerene. Of these, acetylene black or furnace black can be preferably used. The use ratio of the conductive agent is preferably 20 parts by mass or less, more preferably 1 to 15 parts by mass, and particularly preferably 2 to 10 parts by mass based on 100 parts by mass of the electrode active material.

2.2.2. Non-aqueous media

The electrode slurry may contain a nonaqueous medium having a standard boiling point of 80 to 350 DEG C from the viewpoint of improving the applicability thereof. Specific examples of such non-aqueous medium include amide compounds such as N-methylpyrrolidone, dimethylformamide and N, N-dimethylacetamide; Hydrocarbons such as toluene, xylene, n-dodecane and tetralin; 2-ethyl-1-hexanol, 1-nonanol, lauryl alcohol and the like; Ketones such as methyl ethyl ketone, cyclohexanone, phorone, acetophenone, and isophorone; Esters such as benzyl acetate, isopentyl butyrate, methyl lactate, ethyl lactate, and butyl lactate; amine compounds such as o-toluidine, m-toluidine, and p-toluidine; lactones such as? -butyrolactone and? -butyrolactone; Sulfoxide compounds such as dimethyl sulfoxide and sulfolane, and the like, and at least one selected from the above can be used. Of these, it is preferable to use N-methylpyrrolidone from the standpoints of stability of the polymer particles, workability in applying the electrode slurry, and the like.

2.2.3. Thickener

The electrode slurry may contain a thickening agent from the viewpoint of improving the coating property. As specific examples of the thickener, Other additives ".

When the slurry for electrode contains a thickening agent, the proportion of the thickening agent to be used is preferably 20% by mass or less, more preferably 0.1 to 15% by mass, and particularly preferably 0.5 to 5% by mass, based on the total solid content of the electrode slurry. 10% by mass.

2.3. Method for producing slurry for electrodes

The electrode slurry according to the present embodiment can be produced by mixing the above-described binder composition for electrodes, an electrode active material, water, and an additive that is used as needed. These mixing can be carried out by stirring by a known method, for example, a stirrer, a deaerator, a bead mill, a high-pressure homogenizer, or the like can be used.

The preparation of the electrode slurry (mixing operation of each component) is preferably carried out at least in part under reduced pressure. As a result, it is possible to prevent large bubbles from being generated in the obtained electrode active material layer. The degree of the reduced pressure is preferably about 5.0 × 10 ³ to 5.0 × 10 ⁵ Pa at an absolute pressure.

As the mixing and stirring for producing the electrode slurry, it is necessary to select a mixer capable of stirring to such an extent that no agglomerate of the electrode active material is left in the slurry and, if necessary, sufficient dispersion conditions. The degree of dispersion can be measured by a particle gauge, but it is preferable to mix and disperse such that aggregates larger than at least 100 mu m are eliminated. Examples of the mixer suitable for such conditions include a ball mill, a sand mill, a pigment disperser, a brain ball, an ultrasonic disperser, a homogenizer, a planetary mixer, a Hobart mixer and the like.

2.4. Features of electrode slurry

The ratio (Da / Db) of the number average particle diameter (Da) of the polymer particles (A) contained in the electrode binder composition to the number average particle size (Db) of the electrode active material is in the range of 0.01 to 1.0 in the positive electrode And more preferably in the range of 0.05 to 0.5. In the negative electrode, it is preferably in the range of 0.002 to 0.13, more preferably in the range of 0.003 to 0.1. The technical meaning of this is as follows.

It is confirmed that at least one of the polymer particles (A) and the electrode active material migrates in the step of applying the slurry for electrode to the surface of the current collector and then drying the formed coating film. That is, the particles move along the thickness direction of the coating film by being subjected to the action of the surface tension. More specifically, at least one of the polymer particles (A) and the electrode active material moves to the side opposite to the side in contact with the current collector in the coated film surface, that is, the gas-solid interface side where water evaporates. When this migration occurs, the distribution of the polymer particles (A) and the electrode active material becomes uneven in the thickness direction of the coating film, resulting in deterioration of the electrode characteristics or impaired adhesion. For example, when the polymer particles (A) functioning as a binder bleed (transfer) to the gas-solid interface side of the electrode active material layer and the amount of the polymer particles (A) at the interface between the current collector and the electrode active material layer is relatively , Penetration of the electrolyte solution into the electrode active material layer is inhibited and sufficient electrical characteristics can not be obtained and the ability of the current collector and the electrode active material layer to adhere to each other is insufficient and peeled off. Further, when the polymer particles (A) are bleached, the smoothness of the surface of the electrode active material layer is impaired.

However, when the ratio (Da / Db) of the number average particle diameter of both particles is in the above range, the occurrence of the above-described problems can be suppressed, and an electrode with good electrical characteristics and adhesion can be easily manufactured do. If the ratio (Da / Db) is less than the above range, the powder dropout resistance may be insufficient. On the other hand, if the ratio (Da / Db) exceeds the above range, the adhesion ability between the current collector and the electrode active material layer may be insufficient.

The slurry for an electrode according to the present embodiment preferably has a solid concentration (a ratio of the total mass of components other than the solvent in the slurry to the total mass of the slurry) of 20 to 80 mass%, and preferably 30 to 75 mass% More preferable.

The slurry for an electrode according to the present embodiment preferably has a threadability of 30 to 80%, more preferably 33 to 79%, and particularly preferably 35 to 78%. If the preparedness is less than the above range, the leveling property is insufficient when the slurry for electrode is applied on the current collector, so that it may be difficult to obtain the uniformity of the electrode thickness. If an electrode having such a nonuniform thickness is used, the in-plane distribution of the charging / discharging reaction is generated, making it difficult to exhibit stable cell performance. On the other hand, if the prespecification exceeds the above range, liquid slipping easily occurs when the electrode slurry is coated on the current collector, making it difficult to obtain a stable quality electrode. Therefore, when the thermosensitivity falls within the above range, the occurrence of these problems can be suppressed, and it becomes easy to produce an electrode having good electrical properties and adhesion.

The &quot; prospective &quot; in the present specification is measured as follows.

First, a Zahn Cup (Zabisco City Cup No. 5, manufactured by DAIYUKI CHEMICAL INDUSTRIES, LTD.) Having an opening of 5.2 mm in diameter is prepared at the bottom. 40 g of the electrode slurry is introduced into the cups while the openings thereof are closed. Thereafter, when the opening is opened, the electrode slurry flows out from the opening. Herein, when the openings are opened to T ₀ , when the electrode slurry is finished to be preheated to T _A , and when the outflow of the electrode slurry is finished to be T _B , the "prospective" Can be obtained from Equation (6).

&Quot; (6) &quot;

(%) = ((T _A -T ₀ ) / (T _B -T ₀ )) × 100

3. Electrode

An electrode according to an embodiment of the present invention includes a current collector and a layer formed by applying and drying the electrode slurry described above on the surface of the current collector. Such an electrode can be produced by applying a slurry for electrode to the surface of a suitable current collector such as a metal foil to form a coating film, and then drying the coating film to form an electrode active material layer. The electrode thus produced is obtained by binding an electrode active material layer containing the polymer (A) and the electrode active material, and further optionally, optional components, on the current collector. Such an electrode is excellent in adhesion between the current collector and the electrode active material layer, and has excellent charge / discharge rate characteristics, which is one of the electrical characteristics. Therefore, such an electrode is preferable as an electrode of a power storage device.

The current collector is not particularly limited as long as it includes a conductive material. In lithium ion secondary batteries, metal current collectors such as iron, copper, aluminum, nickel, and stainless steel are used. Especially when aluminum is used for the positive electrode and copper is used for the negative electrode, The effect of the slurry is most evident. As the current collector in the nickel hydride secondary battery, a punching metal, an expanded metal, a wire mesh, a foamed metal, a sintered metal fiber sintered body, a metal plated resin plate and the like are used. The shape and thickness of the current collector are not particularly limited, but it is preferable to form the current collector in the form of a sheet having a thickness of about 0.001 to 0.5 mm.

The method of applying the electrode slurry to the current collector is also not particularly limited. The application may be carried out by a suitable method such as a doctor blade method, a dipping method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, or a brush coating method. The amount of the electrode slurry to be applied is not particularly limited. However, the amount of the electrode active material layer formed after removal of the liquid medium (which includes both water and optionally used non-aqueous medium) is 0.005 to 5 mm , More preferably 0.01 to 2 mm. When the thickness of the electrode active material layer is within the above range, it is possible to effectively impregnate the electrode active material layer with the electrolyte solution. As a result, since the exchange of the metal ions involved in charging and discharging of the electrode active material and the electrolytic solution in the electrode active material layer is easily performed, the electrode resistance can be further reduced, which is preferable. Further, since the thickness of the electrode active material layer is within the above range, the electrode active material layer is not peeled off from the current collector even when the electrode is processed by folding or winding the electrode, and the adhesion is good, It is preferable that an electrode is obtained.

There is no particular limitation on the drying method (the method of removing water and optional non-aqueous medium used) from the coated film after application, and for example, drying by hot air, hot air, low-humidity air; Vacuum drying; (Circle) infrared ray, electron beam, or the like. The drying rate can be appropriately set so that the liquid medium can be removed as soon as possible in a speed range in which cracks are generated in the electrode active material layer due to stress concentration or a speed range in which the electrode active material layer is not peeled from the current collector .

It is also preferable to increase the density of the electrode active material layer by pressing the current collector after drying and adjust the porosity to the range shown below. Examples of the pressing method include a die press and a roll press. The conditions of the press should be appropriately set according to the purpose of the type of press machine to be used, the porosity of the electrode active material layer, and the density. This condition can be easily set by a slight preliminary experiment by a person skilled in the art. For example, in the case of a roll press, the line pressure of the roll press is 0.1 to 10 (t / cm), preferably 0.5 to 5 (rotation speed of the roll) of the current collector after drying at a roll temperature of 20 to 100 占 폚 at a pressure of 1 to 80 m / min, preferably 5 to 50 m / min, .

The density of the electrode active material layer after the pressing is preferably 1.5 to 5.0 g / cm ³ , more preferably 1.5 to 4.0 g / cm ³ , and particularly preferably 1.6 to 3.8 g / cm ³ . When the electrode active material is the composite metal oxide represented by the above formula 4a or 4b, the density of the electrode active material layer is preferably 2.0 to 4.0 g / cm ³ , more preferably 3.0 to 3.5 g / cm ³ desirable. When the electrode active material is a compound represented by the above formula (5) and having an olivine crystal structure, the density of the electrode active material layer is preferably 1.5 to 2.5 g / cm ³ , more preferably 1.6 to 2.4 g / cm ³ More preferably 1.7 to 2.2 g / cm &lt; ³ &gt;, and particularly preferably 1.8 to 2.1 g / cm &lt; ³ &gt;. When the density of the electrode active material layer is in the above range, an electrode having good adhesion between the current collector and the electrode active material layer, excellent powder dropout resistance, and excellent electrical characteristics can be obtained. If the density of the electrode active material layer is less than the above range, the polymer (A) in the electrode active material layer does not sufficiently function as a binder, and the electrode active material layer is agglomerated and peeled off, thereby deteriorating the powder decoupability. When the density of the electrode active material layer exceeds the above range, the binder function of the polymer (A) in the electrode active material layer is excessively strong and the binding ability of the electrode active materials becomes excessively strong. As a result, the electrode active material layer can not follow the flexibility of the current collector and the interface between the current collector and the electrode active material layer may peel off, which is not preferable. The &quot; density of the electrode active material layer &quot; in the present invention is a value indicating the bulk density of the electrode active material layer and can be found from the following measurement method. That is, when the mass of the current collector is A (g) and the mass of the electrode for the power storage device is B ((g)) in an electrode having an electrode active material layer having an area C (cm ² ) g), the density of the electrode active material layer is defined by the following equation (7).

&Quot; (7) &quot;

The density of the electrode active material layer ^{(g / cm 3) = (} B (g) -A (g)) / (C (cm 2) × D (㎛) × 10 -4)

The porosity of the electrode active material layer after pressing is preferably 10 to 50%, more preferably 15 to 45%, and particularly preferably 20 to 40%. When the porosity of the electrode active material layer is in the above range, an electrode excellent in bonding ability between the current collector and the electrode active material layer, excellent in drop rejection resistance, and excellent in electrical characteristics is obtained. In addition, when the porosity of the electrode active material layer is in the above range, the electrolyte can be sufficiently impregnated into the electrode active material layer, and the surface of the electrode active material and the electrolyte can sufficiently contact with each other. As a result, the exchange of the lithium ion between the electrode active material and the electrolytic solution becomes easy, and good charge / discharge characteristics can be achieved. The porosity of the electrode active material layer in the present invention refers to the porosity of the electrode active material layer (the amount excluding the volume occupied by the solids (the electrode active material, the conductive agent, and the binder) from the volume of the electrode active material layer) Of the total volume of the active material layer. That is, in an electrode having an electrode active material layer having an area C (cm ² ) and a thickness D (탆) on one side of the current collector, the mass of the electrode active material layer was measured by B (g) When the pore volume is V (cm ³ / g), it is a value defined by the following equation (8).

&Quot; (8) &quot;

(%) Of the electrode active material layer = ((V [cm ³ / g] × B [g]) / (C [cm ² ] × D [μm] × 10 ^-4 )) × 100

The pore volume can be measured, for example, by mercury porosimetry using a mercury porosimeter. As the mercury porosimeter, for example, a product name "PoreMaster" manufactured by Quantachrome, a product name "AUTOFORE IV" manufactured by Shimazu Seisakusho, and the like can be used.

4. Power storage device

The electrical storage device according to one embodiment of the present invention includes the above-described electrode, and can be manufactured according to a conventional method using an electrolyte and a component such as a separator. Specific examples of the production method include a method in which the negative electrode and the positive electrode are overlapped with each other with a separator interposed therebetween, and the battery is wrapped or folded according to the shape of the battery, placed in a battery container, and an electrolyte is injected into the battery container and sealed. The shape of the battery can be any suitable shape such as a coin, button, sheet, cylinder, square, or flat shape.

The electrolytic solution may be in the form of a liquid or a gel, and may be selected so as to effectively express its function as a battery from a known electrolytic solution used in a power storage device depending on the type of the electrode active material. The electrolytic solution may be a solution in which the electrolyte is dissolved in a suitable solvent.

As the electrolyte, any of conventionally known lithium salts may be used in the lithium ion secondary battery. Specific examples thereof include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiB _{10 Cl 10, LiAlCl 4, LiCl} , LiBr, LiB (C 2 H 5) 4, LiCF 3 SO 3, LiCH 3 SO 3, LiC 4 F 9 SO 3, Li (CF 3 SO 2) 2 N, lower fatty acid And lithium bicarbonate. In the nickel-metal hydride secondary battery, for example, an aqueous potassium hydroxide solution having a conventionally known concentration of 5 mol / liter or more can be used.

The solvent for dissolving the electrolyte is not particularly limited, but specific examples thereof include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl A carbonate compound such as carbonate; lactone compounds such as? -butyrolactone; Ether compounds such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran; And sulfoxide compounds such as dimethylsulfoxide, and the like, and at least one selected from these may be used. The concentration of the electrolyte in the electrolytic solution is preferably 0.5 to 3.0 mol / L, more preferably 0.7 to 2.0 mol / L.

5. Example

Hereinafter, the present invention will be described concretely based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "part" and "%" are on a mass basis unless otherwise specified.

5.1. Example 1

5.1.1. Production of polymer particles (A)

After thoroughly purging the inside of an internal volume of about 6 L autoclave equipped with an electromagnetic stirrer with nitrogen, 2.5 L of deoxygenated pure water and 25 g of ammonium perfluorodecanoate as an emulsifier were added , And the mixture was heated to 60 DEG C while stirring at 350 rpm. Subsequently, a mixed gas containing 70% of monomer vinylidene fluoride (VDF) and 30% of propylene hexafluoride (HFP) was added until the internal pressure reached 20 kg / cm ² . 25 g of Freon 113 solution containing 20% of diisopropyl peroxydicarbonate as a polymerization initiator was introduced by using nitrogen gas to initiate polymerization. During the polymerization, a mixed gas containing 60.2% of VDF and 39.8% of HFP was continuously pressurized to maintain the internal pressure at 20 kg / cm ² , and the pressure was maintained at 20 kg / cm ² . Further, since the polymerization rate decreased as the polymerization proceeded, the same amount of the same polymerization initiator solution as before was injected using nitrogen gas after 3 hours, and the reaction was further continued for 3 hours. Thereafter, the reaction solution was cooled and at the same time, the stirring was stopped, unreacted monomers were released, and the reaction was stopped to obtain an aqueous dispersion containing 40% of the polymer (Aa) fine particles. As a result of ¹⁹ F-NMR analysis of the obtained polymer (Aa), the mass composition ratio of each monomer was VDF / HFP = 21/4.

After sufficiently replacing the inside of the separable flask having a capacity of 7 L with nitrogen, 1,600 g (corresponding to 25 parts by mass in terms of the polymer (Aa)) of the aqueous dispersion containing fine particles of the polymer (Aa) obtained in the above- (MMA), 40 parts by mass of 2-ethylhexyl acrylate (EHA), and 5 parts by mass of methacrylic acid (MAA) 5 (trade name, manufactured by Adeka Co., And 130 parts by mass of water were added in this order and the mixture was stirred at 70 캜 for 3 hours to absorb the monomer into the polymer (Aa). Subsequently, 20 mL of a tetrahydrofuran solution containing 0.5 part by mass of azobisisobutyronitrile as an oil-soluble polymerization initiator was added, and the mixture was heated to 75 DEG C for 3 hours, and further reacted at 85 DEG C for 2 hours. Thereafter, the reaction was stopped after cooling, and the pH was adjusted to 7 with 2.5 N aqueous sodium hydroxide solution to obtain an aqueous dispersion containing 40% of the polymer particles (A).

About 10 g of the obtained aqueous dispersion was weighed into a Teflon chalet having a diameter of 8 cm and dried at 120 ° C for 1 hour to form a film. 1 g of the obtained membrane (polymer) was immersed in 400 mL of tetrahydrofuran (THF) and shaken at 50 DEG C for 3 hours. Subsequently, the THF phase was filtered with a 300-mesh wire net to remove the insoluble matter, and the weight (Y (g)) of the remnant obtained by removing the THF of the dissolved substance by evaporation was measured. Min, the THF insolubles of the polymer particles were 85%.

&Quot; (9) &quot;

THF insoluble matter (%) = ((1-Y) / 1) 100

Further, when the obtained fine particles were measured by a differential scanning calorimeter (DSC), only one single glass transition temperature Tg was observed at -5 deg. Despite using two kinds of polymers, since the obtained polymer particles (A) show only one Tg, it can be inferred that the polymer particles (A) are polymer particle particles.

5.1.2. Preparation of Binder Composition for Electrode

31 g of a water suspension containing 1% of 2-methyl-4-isothiazolin-3-one was added to 1,000 g of the aqueous dispersion containing the polymer particles (A) obtained above and stirred at 300 rpm, Lt; / RTI &gt; was prepared. In the following examples and comparative examples, when the component (B) was insoluble in water, a dispersion liquid in a state of being dispersed in an aqueous solution by ultrasonic waves was added to prepare a binder composition for electrodes.

The obtained binder composition for electrodes was subjected to a particle size distribution measurement using a particle size distribution measuring apparatus (type "FPAR-1000" manufactured by Otsuka Denshi Kabushiki Kaisha) with a dynamic light scattering method as a measurement principle, When the particle diameter was determined, the number average particle diameter was 330 nm.

The content of the component (B) in the electrode binder composition can also be confirmed by analyzing the binder composition for electrodes by the following procedure. That is, 2.0 g of the obtained binder composition for electrode was weighed, and an aqueous solution of aluminum sulfate was added to coagulate. Next, the aggregated polymer components were filtered and washed with a high-performance liquid chromatography apparatus (column: Waters, μBondasphere 5 μC18-100 Å (inner diameter: 3.9 mm, length: 150 mm), mobile phase: 0.01 M acetic acid The mixture was adjusted to pH 4.0 by adding trifluoroacetic acid to 2 L of ammonium and then mixed with 500 mL of acetonitrile for high performance liquid chromatography, flow rate: 0.6 mL / min). As a result, 2- It was confirmed that the content of methyl-4-isothiazolin-3-one was 300 ppm.

5.1.3. Evaluation of Storage Stability of Binder Composition for Electrode

In general, a binder composition for an electrode is stored in a large amount in preparation for use in a factory for manufacturing a power storage device. And, a large amount of the binder composition for electrodes is consecutively consumed as needed. When bacteria or the like reproduce during storage of the electrode binder composition, aggregation tends to occur in the electrode slurry produced by using the electrode binder composition, which may deteriorate the crack resistance or charge / discharge characteristics of the electrical storage device Which is undesirable.

In addition, the storage environment of the electrode binder composition can not be strictly controlled in terms of cost from the viewpoint of cost, and therefore it is often exposed to an environment near 0 캜 according to a change in temperature. Therefore, it is not allowed to freeze at 0 캜 in the following evaluation of the freezing temperature, and it is required that the freezing temperature is -0.5 캜 or lower. Therefore, when the freezing temperature is -0.5 DEG C or less, stability of the electrode binder composition is high and can be judged to be good.

In addition, the storage of the electrode binder composition may take a long time (several months to several years). Therefore, even when the binder composition for electrodes stored for a long period of time is used, it is necessary that the performance of the obtained electrode such as charge / discharge characteristics is constant. Therefore, Manufacture and evaluation of electrical storage devices ", it was judged that the electrode prepared by using the binder composition after storage for a long time exhibited good storage stability over a long period of time in the case of exhibiting excellent charging and discharging characteristics from the electrode prepared using the binder composition immediately after preparation can do.

<Corruption test>

5 g of the bacterial solution was added to 100 g of the binder composition for electrodes prepared above, and the mixture was stored at 35 DEG C for 2 weeks. Then, 5 g of the bacterial solution was further added and stored at 35 DEG C for 2 months. The bacterial counts of the electrode binder composition were cultured in a thermostat at 28 DEG C for 48 hours using commercially available &quot; EASICULT TTC &quot; (manufactured by Orion Diagnostica, Finland) Were compared with the charts. Also, "5.1.1. The polymer particles (A) produced in the section of production "of the polymer particles (A) in the aqueous dispersion containing 40% by corruption by the addition of foot lance (comamonas acidovorans) coma Pseudomonas know as the indicator bacteria, bacterial count of 10 ⁷ Ml / ml was used as the bacterial solution.

Here, the binder composition for electrodes having excellent storage stability has a small number of bacteria. It is preferable that the number of bacteria is 0 / ml. When the number of bacteria is 10 ⁴ / ml, the number of bacteria is acceptable. If the number of bacteria is less than 10 ³ / ml, . However, when the number of bacteria is larger than 10 ⁴ / ml, foreign matter generated by the bacteria increases, making it impossible to produce a homogeneous electrode, thereby deteriorating the productivity of the electrode. From this, it is considered that the range of up to 10 ⁴ / ml as the threshold value of the number of bacteria is a preferable range. The evaluation criteria are as follows, and the evaluation results are shown together in Table 1.

○: the number of bacteria was less than 10 ³ / ml

△: Number of bacteria was 10 ³ / ml or more 10 ⁴ cells / ml or less

X: number of bacteria is 10 ⁴ / ml or more

&Lt; Evaluation of freezing temperature &

1000 g of the binder composition for electrodes prepared above was filled in a poly bottle and then stored in a freezer at -10 캜 to measure the temperature (freezing temperature) at which the freezing starts. As a result, the freezing temperature of the electrode binder composition was -0.6 ° C. The results of the freezing temperature evaluation are shown together in Table 1.

5.1.4. Preparation and evaluation of electrode slurry

1 part by mass of a thickener (trade name &quot; CMC1120 &quot;, manufactured by Daicel Chemical Industries, Ltd.) (trade name: TK Hybis Mix 2P-03, manufactured by Flymix Co., ), commercially available lithium iron phosphate (LiFePO _4), the particle size obtained by grinding in an agate mortar and classified by a sieve (D50 value) of 0.5 ㎛ the electrode active material to 100 parts by mass of acetylene black 5 weight parts and water 68 parts by weight is And the mixture was stirred at 60 rpm for 1 hour. Subsequently, Preparation of electrode binder composition "was added so that the polymer particles contained in the composition were added in an amount of 1 part by mass, and the mixture was further stirred for 1 hour to obtain a paste. Water was added to the obtained paste to adjust the solid content concentration to 50%, and the mixture was stirred at 200 rpm for 2 minutes, at 1,800 rpm for 5 minutes, using a stirring deaerator (trade name: Awadori Rantaro, And further agitated and mixed under vacuum (about 5.0 × 10 ³ Pa) at 1,800 rpm for 1.5 minutes to prepare an electrode slurry.

&Lt; Measurement of uniformity &

The preliminarily measured slurry of the obtained electrode slurry was measured as follows.

First, a cup (Zanesco City Cup No. 5, manufactured by Daiei Kikai Kagaku Kagaku Co., Ltd.) having an opening of 5.2 mm in diameter was prepared at the bottom of the container. In the state that the opening of the cup remained closed, 40 g of the electrode slurry prepared above was introduced. When the opening was opened, the slurry flowed out. At this time, the time at the moment when the opening was opened was T ₀ , the time when the slurry was drained when the slurry flowed out was continuously measured and visually measured, and this time was defined as T _A. Further, the measurement was continued even after the yarn could no longer be attracted, and the time T _B until the electrode slurry was no longer discharged was measured. The measured values T ₀ , T _A, and T _B were substituted into the following equation (6) to determine the predictive value.

&Quot; (6) &quot;

(%) = ((T _A -T ₀ ) / (T _B -T ₀ )) × 100

It can be judged to be satisfactory in the case where the slurry of the electrode slurry has a prespecificity of 30 to 80%. Table 1 shows the measurement results of the regularity.

5.1.5. Preparation and evaluation of electrodes

The electrode slurry prepared above was uniformly coated on the surface of a current collector containing an aluminum foil having a thickness of 30 占 퐉 by a doctor blade method so as to have a film thickness after drying of 100 占 퐉 and dried at 120 占 폚 for 20 minutes. Thereafter, the electrode (positive electrode) was obtained by press working by a roll press machine so that the density of the film (electrode active material layer) was the value shown in Table 1.

<Measurement of Peel Strength>

A test piece having a width of 2 cm and a length of 12 cm was cut out from the obtained electrode, and the surface of the electrode active material layer side of the test piece was attached to the aluminum plate using a double-faced tape. On the other hand, a 18 mm wide tape (manufactured by Nichiban K.K., trade name "Cellophane Tape (registered trademark)", as specified in JIS Z1522) was attached to the surface of the current collector of the test piece. The strength (mN / 2 cm) when the 2-cm stripping of the 18 mm wide tape at a speed of 50 mm / min in the 90 direction was measured six times and the average value thereof was measured as the adhesion strength (peel strength, mN / . The larger the value of the peel strength is, the higher the adhesion strength between the current collector and the electrode active material layer is, and it can be estimated that the electrode active material layer is difficult to peel off from the collector. When the value of the peel strength is 20 mN / . The results of measurement of the peel strength are shown together in Table 1.

<Measurement of Cracking Rate>

The obtained electrode was cut into a 2 cm wide x 10 cm long electrode plate, and a bending test was carried out by repeating the number of times of bending of the positive electrode plate along a round bar having a diameter of 2 mm in the width direction. The size of the cracks along the round bar was observed by visual observation and the cracking rate was measured. The cracking rate was defined by the following equation (10).

&Quot; (10) &quot;

 Cracking rate (%) = (length of cracked [mm] / length of entire plate [mm]) × 100

Here, the electrode plate having excellent flexibility and adhesion has a low cracking rate. It is preferable that the cracking rate is 0%, but when the electrode plate group is manufactured by spirally winding it with the separator interposed therebetween, it is allowed that the cracking rate is up to 20%. However, if the cracking rate is larger than 20%, the electrode tends to be broken, making it impossible to manufacture the electrode plate group, and the productivity of the electrode plate group is lowered. From this, it is considered that the range up to 20% is a good range as the threshold value of the cracking rate. The results of the measurement of the cracking rate are shown in Table 1.

5.1.6. Fabrication and evaluation of power storage devices

&Lt; Preparation of Relative Electrode (Negative Electrode) >

, 4 parts by mass (in terms of solid content) of polyvinylidene fluoride (PVDF) and 100 parts by mass of graphite as a negative electrode active material were added to a twin-screw type planetary mixer (trade name: TK Hybis Mix 2P-03 manufactured by Flymix Co., (In terms of solid content) and 80 parts by mass of N-methylpyrrolidone (NMP), and the mixture was stirred at 60 rpm for 1 hour. Thereafter, 20 parts by mass of NMP was further added, followed by stirring at 200 rpm for 2 minutes and then at 1,800 rpm for 5 minutes using a stirring deaerator (manufactured by Shinki Kabushiki Kaisha Ltd., product name "Awadorylene Taro" and further stirred and mixed at rpm for 1.5 minutes to prepare a slurry for a counter electrode (negative electrode).

The slurry for the counter electrode (negative electrode) prepared above was uniformly coated on the surface of the current collector including the copper foil by a doctor blade method so as to have a film thickness after drying of 150 mu m and dried at 120 DEG C for 20 minutes. Thereafter, a relative pole (negative electrode) was obtained by pressing using a roll press machine so that the density of the film was 1.5 g / cm ³ .

<Assembly of lithium ion battery cell>

The electrode (negative electrode) prepared above was punched with a diameter of 15.95 mm in an Ar-substituted glove box so that the dew point became -80 占 폚 or less. This was a bipolar coin cell (trade name: HS flat cell Quot;). Then, a separator (manufactured by Celgard Corporation, trade name &quot; Celgard # 2400 &quot;) containing a porous film made of polypropylene punched with a diameter of 24 mm was placed and 500 μL of an electrolyte solution was injected so as to prevent air from entering. The positive electrode of the bipolar coin cell was closed with a screw and sealed to assemble the lithium ion battery cell (battery device). The electrolytic solution used herein was a solution in which LiPF ₆ was dissolved in a solvent of ethylene carbonate / ethyl methyl carbonate = 1/1 (mass ratio) at a concentration of 1 mol / L.

<Evaluation of charge / discharge rate characteristics>

Charging was started at a constant current (0.2 C) to the above-described power storage device. When the voltage became 4.2 V, the charging device was continuously charged at a constant voltage (4.2 V). When the current value reached 0.01 C, (Cut-off), and the charge capacity at 0.2 C was measured. Then, the discharge was started at a constant current (0.2 C). When the voltage reached 2.7 V, discharge was completed (cut-off), and the discharge capacity at 0.2 C was measured.

Subsequently, the same cells were charged with a constant current (3 C). When the voltage reached 4.2 V, charging was continued at a constant voltage (4.2 V). When the current value reached 0.01 C, Cut-off), and the charge capacity at 3 C was measured. Subsequently, discharging was started at a constant current (3 C). When the voltage reached 2.7 V, discharge was completed (cut-off), and the discharge capacity at 3 C was measured.

Using the above measured values, the charge rate (%) was calculated by multiplying the charge rate (%) at 3 C by the ratio of the charge capacity at 3 C to the charge capacity at 0.2 C The discharge rate (%) was calculated by calculating the ratio of the discharge capacity (percentage%). When both the charging rate and the discharging rate are 80% or more, the charging / discharging rate characteristics can be evaluated as being good. The values of the measured charge rate and discharge rate are shown in Table 1, respectively.

<Evaluation of charge / discharge rate characteristics after long-term storage>

5.1.2. Manufacture of Binder Composition for Electrode ", 1000 g of the binder composition for electrode was filled in a poly bottle and stored in a refrigerator set at 2 캜 for 5 months. An electrode was prepared using the electrode binder composition after the storage, and the charge / discharge rate characteristics after storage for a long period of time were evaluated in the same manner as in the evaluation of the charge / discharge rate characteristics. The values of the measured charge rate and discharge rate are shown in Table 1, respectively.

In the measurement conditions, &quot; 1C &quot; indicates a current value at which the discharge is terminated in one hour by constant current discharge of a cell having a certain constant capacity. For example, &quot; 0.1C &quot; refers to a current value at which discharge is completed over 10 hours, and &quot; 10C &quot; refers to a current value at which discharge is completed over 0.1 hour.

5.2. Examples 2 to 7 and Comparative Example 1

&Quot; 5.1.1. Preparation of Polymer Particles (A) &quot;, an aqueous dispersion containing polymer particles (A) having the composition shown in Table 1 was produced in the same manner as in Example 1 except that the composition of the monomers and the amount of emulsifier were appropriately changed, Water was removed under reduced pressure or added in accordance with the solid content concentration of the aqueous dispersion to obtain an aqueous dispersion having a solid content concentration of 40%. In addition, when the fine particles obtained in Examples 2 to 7 and Comparative Example 1 were measured by a differential scanning calorimeter (DSC), only one glass transition temperature Tg was observed at the temperatures listed in Table 1. Despite using two kinds of polymers, since the obtained polymer particles (A) show only one Tg, it can be inferred that the polymer particles (A) are polymer particle particles.

Subsequently, in Example 5.1, "5.1.2. A binder composition for electrodes was prepared in the same manner as in Example 1 except that the amounts of the component (A) and the component (B) were changed in accordance with the kind and the addition amount in Table 1 in the preparation of the electrode binder composition. The obtained binder composition for electrodes was prepared in the same manner as in &quot; 5.1.3. Evaluation of storage stability of electrode binder composition &quot; The results are also shown in Table 1.

In addition, &quot; 5.1.4. Preparation and evaluation of slurry for electrode &quot;, &quot; 5.1.5. Manufacture and Evaluation of Electrode "," 5.1.6. Manufacture and evaluation of electrical storage device &quot;, the electrode slurry, electrode, and electrical storage device were produced and evaluated. The results are also shown in Table 1.

5.3. Comparative Example A

150 parts by mass of water and 0.2 part by mass of sodium dodecylbenzenesulfonate were introduced into a separable flask having a capacity of 7 liters, and the interior of the separable flask was thoroughly purged with nitrogen. On the other hand, 60 parts by mass of water was added to a separate vessel, 0.8 parts by mass of an ether sulfate type emulsifier (trade name &quot; Adekariassof SR1025 &quot;, manufactured by Adeka Co., Ltd.) in terms of solid content as an emulsifier, 20 parts by mass of trifluoroethylmethacrylate (TFEMA), 10 parts by mass of acrylonitrile (AN), 25 parts by mass of methyl methacrylate (MMA), 40 parts by mass of 2-ethylhexyl acrylate (EHA) (AA) were added and sufficiently stirred to prepare a monomer emulsion containing the mixture of monomers. Thereafter, the internal temperature of the separable flask was started to increase. When the internal temperature of the separable flask reached 60 캜, 0.5 part by mass of ammonium persulfate was added as a polymerization initiator. Further, when the internal temperature of the separable flask reached 70 캜, the addition of the monomer emulsion prepared above was started, and while the internal temperature of the separable flask was maintained at 70 캜, the monomer emulsion was slowly added over 3 hours. Thereafter, the internal temperature of the separable flask was raised to 85 캜, and this temperature was maintained for 3 hours to carry out the polymerization reaction. After 3 hours, the separable flask was cooled to quench the reaction, and aqueous ammonium was added to adjust the pH to 7.6 to obtain an aqueous dispersion containing 30% of the polymer particles (A).

A binder composition for an electrode, a slurry for an electrode, an electrode and a battery device were produced and evaluated in the same manner as in Example 1 except that the aqueous dispersion obtained above was used.

5.4. Comparative Examples B to C

An aqueous dispersion containing the polymer particles (A) shown in Table 1 was obtained in the same manner as in Comparative Example A, except that the kind and the amount (parts) of each monomer were changed as shown in Table 1, respectively. An electrode binder composition, an electrode slurry, an electrode, and a battery device were produced and evaluated in the same manner as in Example 1 except that the aqueous dispersion thus obtained was used.

5.5. Example 11

A thermostable autoclave equipped with a stirrer was charged with 200 parts by mass of water, 0.9 parts by mass of sodium dodecylbenzenesulfonate, 1.0 part by mass of potassium persulfate, 0.5 parts by mass of sodium bisulfate, 0.2 parts by mass of? -Methylstyrene dimer, , And the first-stage polymerization components shown in Table 3 were charged in a lump, and the mixture was heated to 70 캜 and subjected to a polymerization reaction for 2 hours. After confirming that the polymerization addition rate was 80% or more, the second-stage polymerization component shown in Table 3 was added over 6 hours while maintaining the reaction temperature at 70 占 폚. At the point in time three hours after the start of the addition of the polymerization component in the second stage, 1.0 part by mass of? -Methylstyrene dimer and 0.3 part by mass of dodecylmercaptan were added. After completion of the addition of the polymerization component in the second stage, the temperature was raised to 80 캜 and further reacted for 2 hours. After completion of the polymerization reaction, the pH of the latex was adjusted to 7.5, and 5 parts by mass of sodium tripolyphosphate (in terms of solid content) was added. Thereafter, the residual monomer was treated with steam distillation and concentrated under reduced pressure to a solid content of 50% to obtain an aqueous dispersion containing 50% of the polymer particles (A).

A binder composition for an electrode, a slurry for an electrode, an electrode and a battery device were produced and evaluated in the same manner as in Example 1 except that the aqueous dispersion obtained above was used.

5.6. Examples 12 to 15 and Comparative Examples 2 to 9

An aqueous dispersion containing the polymer particles (A) having the composition shown in Table 2 was prepared in the same manner as in Example 11 except that the composition of the monomers and the amount of the emulsifier were appropriately changed in Example 11, Water was removed or added under reduced pressure in accordance with the solid content concentration of the solid content concentration to obtain an aqueous dispersion having a solid content concentration of 50%.

A binder composition for an electrode, a slurry for an electrode, an electrode and a battery device were produced and evaluated in the same manner as in Example 1 except that the aqueous dispersion obtained above was used.

5.7. Evaluation results

Table 1 shows the compositions of the binder for electrodes and the evaluation results described above for Examples 1 to 7, Comparative Examples A to C, and Comparative Example 1, together.

The abbreviations of the respective components in Table 1 are as follows.

ㆍ VDF: vinylidene fluoride

ㆍ HFP: propylene hexafluoride

TFEMA: 2,2,2-trifluoroethyl methacrylate

TFEA: 2,2,2-trifluoroethyl acrylate

ㆍ HFIPA: 1,1,1,3,3,3-hexafluoroisopropyl acrylate

MMA: methyl methacrylate

ㆍ EHA: 2-ethylhexyl acrylate

ㆍ MAA: Methacrylic acid

AA: Acrylic acid

ㆍ DVB: divinylbenzene

TMPTMA: trimethylolpropane trimethacrylate

ㆍ AN: acrylonitrile

As is apparent from Table 1, the electrode binder composition according to the present invention shown in Examples 1 to 7 had good storage stability, and the electrode slurry prepared using the binder composition for electrodes according to the present invention had a good wet- And the electrode active material layer is good, it is possible to provide an electrode having a low cracking rate and excellent adhesion. In addition, a charging device (lithium ion secondary battery) including these electrodes had a good charging / discharging rate characteristic. Further, a battery device (lithium ion secondary battery) comprising electrodes fabricated using the binder composition for electrodes according to Examples 1 to 7 stored in a refrigerator set at 2 占 폚 for 5 months had a binder composition for electrodes immediately after preparation A charge / discharge rate characteristic almost free from fading was obtained as compared with the case where it was used.

On the other hand, in the binder composition shown in Comparative Example 1, since the storage stability was not excellent, it was considered that the agglomeration occurred in the electrode slurry and the crack resistance of the electrode deteriorated. Further, since the binder composition shown in Comparative Example 1 is not excellent in storage stability for a long period of time, a battery device (lithium ion secondary battery) comprising an electrode manufactured by a binder composition after storage for a long period of time, It was found that the charge / discharge rate characteristics were poor as compared with the case where the charge / discharge characteristics were used.

Further, as described above, it was estimated from the DSC chart that the polymer particles (A) used in Examples 1 to 7 and Comparative Example 1 were polymer particle particles.

1 is a DSC chart of the polymer particles (A) obtained in Example 3. Fig. In Example 3, the polymer particles are considered to be polymer particles containing at least two kinds of polymers because they are further polymerized by adding monomers to the fine particles of the polymer particles (Aa). However, as apparent from Fig. 1, the two types of Tg derived from these two kinds of polymers can not be confirmed, and only one Tg is observed. This indicates that the polymer particles prepared in the same manner as in Example 3 are in a state of polymer alloy.

Table 2 shows the composition of the binder for electrodes relating to Examples 11 to 15 and Comparative Examples 2 to 9 and the above evaluation results. The content ratios of the first-stage polymerization component and the second-stage polymerization component in the production of the aqueous dispersion containing the polymer particles (A) of Examples 11 to 15 and Comparative Examples 2 to 9 are shown in Table 3.

The abbreviations of the respective components in Table 2 and Table 3 are as follows.

MMA: methyl methacrylate

HEMA: 2-hydroxyethyl methacrylate

AA: Acrylic acid

TA: Itaconic acid

AN: acrylonitrile

BD: 1,3-butadiene

· ST: Styrene

As is apparent from Table 2, the binder compositions for electrodes according to the present invention shown in Examples 11 to 15 had good storage stability, and the electrode slurry prepared using the binder composition for electrodes according to the present invention had a Since the adhesion ability between the entire electrode active material layer and the electrode active material layer is good, the electrode has a low cracking rate and excellent adhesion. In addition, a charging device (lithium ion secondary battery) including these electrodes had a good charging / discharging rate characteristic. Further, a battery device (lithium ion secondary battery) comprising electrodes manufactured by using the binder composition for electrodes according to Examples 11 to 15 stored in a refrigerator set at 2 占 폚 for 5 months had a binder composition for electrodes A charge / discharge rate characteristic almost free from fading was obtained as compared with the case where it was used.

On the other hand, in the binder composition shown in Comparative Example 3 which does not contain the isothiazoline compound (B), the storage stability was not excellent, so that the electrode slurry was found to be agglomerated, .

In addition, since the binder compositions shown in Comparative Examples 2 to 9 do not have excellent storage stability for a long period of time, a storage device (lithium ion secondary battery) comprising an electrode manufactured by a binder composition after storage for a long period of time, It has been found that the charge / discharge rate characteristics are poor as compared with the case where the binder composition is used.

The present invention is not limited to the above-described embodiment, and various modifications are possible. The present invention includes substantially the same configuration as the configuration described in the embodiment (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect). Further, the present invention includes a configuration in which a non-essential part of the configuration described in the above embodiments is replaced with another configuration. The present invention also includes configurations that exhibit the same operational effects as those described in the above embodiments, and configurations that can achieve the same purpose. The present invention also includes a configuration in which known technologies are added to the configurations described in the above embodiments.

Claims (13)

A binder composition for producing an electrode for use in a power storage device,
(A), an isothiazoline compound (B) and a liquid medium (C)
The polymer (A)
(Ma) derived from at least one fluorine-containing ethylenic monomer selected from the group consisting of vinylidene fluoride, ethylene tetrafluoride and propylene hexafluoride,
The repeating unit (Mb) derived from the unsaturated carboxylic acid ester
Wherein the fluorine-containing polymer particles are fluorine-containing polymer particles. The fluorine-containing polymer particles according to claim 1, wherein the fluorine-containing polymer particles are subjected to differential scanning calorimetry (DSC) in accordance with JIS K7121, wherein the electrode having only one endothermic peak in a temperature range of -50 to + Lt; / RTI &gt; 3. The binder composition according to claim 2, wherein the endothermic peak is observed in a temperature range of -30 to + 30 占 폚. The binder composition for electrodes according to claim 1, wherein the concentration of the compound (B) contained in the binder composition is 50 to 1,500 ppm. The binder composition for electrodes according to claim 1, wherein the compound (B) is at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2).
&Lt; Formula 1 >

(Wherein R ¹ represents a hydrogen atom or a hydrocarbon group, and R ² and R ³ each represent a hydrogen atom, a halogen atom or a hydrocarbon group)
(2)

(Wherein R ⁴ represents a hydrogen atom or a hydrocarbon group, R ⁵ independently represents a hydrogen atom or an organic group, and n represents an integer of 0 to 4) The binder composition for electrodes according to claim 1, wherein the fluorine-containing polymer particles have a number-average particle diameter of 50 to 400 nm. A binder composition for producing an electrode for use in a power storage device,
(A), an isothiazoline compound (B) and a liquid medium (C)
The polymer (A)
The repeating unit (Mc) derived from the conjugated diene compound,
A repeating unit (Md) derived from an aromatic vinyl compound,
(Me) derived from a (meth) acrylate compound,
The repeating unit (Mf) derived from the unsaturated carboxylic acid
Based polymer particles,
Wherein the concentration of the compound (B) contained in the binder composition is from 50 ppm to less than 200 ppm. 9. The method for producing an electrode according to claim 7, wherein the diene polymer particles are subjected to differential scanning calorimetry (DSC) according to JIS K7121 for an electrode in which only one endothermic peak is observed in a temperature range of -40 to + Binder composition. The binder composition for electrodes according to claim 7, wherein the compound (B) is at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2).
&Lt; Formula 1 >

(Wherein R ¹ represents a hydrogen atom or a hydrocarbon group, and R ² and R ³ each represent a hydrogen atom, a halogen atom or a hydrocarbon group)
(2)

(Wherein R ⁴ represents a hydrogen atom or a hydrocarbon group, R ⁵ independently represents a hydrogen atom or an organic group, and n represents an integer of 0 to 4) The binder composition for electrodes according to claim 7, wherein the diene polymer particles have a number average particle diameter of 50 to 400 nm. The electrode binder composition according to any one of claims 1 to 10 and an electrode slurry containing an electrode active material. 11. An electrode comprising a current collector and a layer formed by applying and drying the electrode slurry according to claim 11 on the surface of the current collector. An electrical storage device comprising the electrode according to claim 12.

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