KR20130113442A - Aqueous binder composition for secondary battery cathode, slurry composition for secondary battery cathode, secondary battery cathode, and secondary battery - Google Patents

Abstract

(Problem) The aqueous binder composition for secondary battery positive electrodes which can be excellent in long-term storage stability, and can improve cycling characteristics and safety of the secondary battery obtained, the slurry composition for secondary battery positive electrodes using this binder composition, a secondary battery positive electrode, and a secondary battery To provide.
(Solution means) The aqueous binder composition for secondary battery positive electrodes according to the present invention is a binder having a (meth) acrylic acid ester monomer unit, a vinyl monomer unit having an acid group, and an α, β-unsaturated nitrile monomer unit, and the binder 100 mass It is characterized by containing 0.001-1.0 mass part of isothiazoline type-compounds and 0.001-1.0 mass part of chelate compounds with respect to a part.

Description

Aqueous BINDER COMPOSITION FOR SECONDARY BATTERY CATHODE, SLURRY COMPOSITION FOR SECONDARY BATTERY CATHODE, SECONDARY BATTERY CATHODE, AND SECONDARY BATTERY}

This invention relates to the aqueous binder composition for secondary battery positive electrodes used in order to form the positive electrode used for secondary batteries, such as a lithium ion secondary battery.

Recently, the popularity of portable terminals such as notebook computers, cellular phones, PDAs (Personal Digital Assistants) and the like is remarkable. Nickel hydrogen secondary batteries, lithium ion secondary batteries, and the like are frequently used as secondary batteries used for power sources of these portable terminals. As portable terminals demand more comfortable portability, miniaturization, thinning, weight reduction, and high performance are rapidly progressing, and as a result, portable terminals are used in various places. In addition, in the case of batteries, miniaturization, thinning, weight reduction, and high performance are demanded, similarly to portable terminals.

For example, a lithium ion secondary battery using a conductive carbonaceous material that occludes and releases lithium ions as a negative electrode active material has a conductive carbonaceous material as a negative electrode active material from its characteristics of being light in weight and high in energy density. As the binder, a polymer binder (hereinafter sometimes referred to as "binder") is used.

The polymer binder is required to have adhesion with an active material, resistance to a polar solvent used as an electrolyte, and stability under an electrochemical environment. Conventionally, fluorine-based polymers such as polyvinylidene fluoride have been used in this field, but there is a problem in that when the electrode film is formed, the conductivity is inhibited or the adhesive strength between the current collector and the electrode film is insufficient.

In particular, when a fluorine-based polymer is used for the negative electrode serving as reducing conditions, the stability is not sufficient, and there is also a problem that the cycleability of the secondary battery is lowered. For example, a styrene-butadiene-based binder or the like is also known as a non-fluorine-based polymer. have.

As the negative electrode active material that is a constituent material of the lithium ion secondary battery, carbon materials such as graphite capable of occluding and releasing lithium ions, lithium metal or alloys thereof, and metal oxides such as TiO ₂ and SnO ₂ are also used. In the case, trace amounts of conductive impurities such as iron may be contained, and since they form aqueous phase metal precipitates on the surface of the negative electrode with charging and discharging, the battery capacity, lifespan, and safety deterioration may be reduced. There is a problem.

On the other hand, an active material containing transition metals such as iron, manganese, cobalt, chromium, and copper is used as the positive electrode active material that is a constituent material of the lithium ion secondary battery. When the secondary battery using these active materials repeats charging / discharging, transition metal ions elute in electrolyte solution, and as a result, a battery capacity and cycling characteristics may fall, and it became a big subject.

In addition, the transition metal ions eluted from the positive electrode are reduced and precipitated on the surface of the negative electrode, thereby forming a metal precipitate in the water phase, which damages the separator, thereby deteriorating safety as a battery.

The electrode used for a lithium ion secondary battery normally has the structure in which the electrode active material layer was laminated | stacked on the electrical power collector, and a binder is attached to the electrode active material layer in order to bind electrode active materials, an electrode active material, and an electrical power collector other than an electrode active material. It is used. The electrode usually obtains a slurry composition by mixing an active material and a conductive agent such as conductive carbon, if necessary, in a binder composition in which a polymer serving as a binder is dispersed or dissolved in a liquid medium such as water or an organic liquid, to obtain a slurry composition. It is applied to the whole and manufactured by drying.

Patent Document 1 describes a binder composition in which a polymer serving as a binder is dispersed in water as a binder composition having superior performance, safety, and environmental viewpoints than a binder composition using an organic liquid medium. In addition, Patent Document 1 describes the use of a positive electrode active material containing manganese and cobalt.

Japanese Laid-Open Patent Publication 2005-85557

However, according to the inventors' review, the aqueous binder composition described in Patent Literature 1 has a long-term storage in storage in a storage tank after manufacture, or during long-term storage in a shipping container such as a container or a poly container. Viscosity changes of the composition may occur or aggregates may occur. Furthermore, the slurry composition obtained by mixing with an electrode active material may also generate a viscosity change and generate | occur | produce agglomerates, As a result, the desired electrode plate may not be manufactured or a deviation may be observed in the characteristic of the obtained battery.

In addition, in the secondary battery described in Patent Literature 1, when charge and discharge are repeated, there is a problem that transition metal ions are eluted in the electrolytic solution, and as a result, the battery capacity is lowered, and the eluted transition metal ions precipitate on the negative electrode surface. It turned out that there exists a problem that the lifetime (especially high temperature cycling characteristics) and safety of a battery fall by doing so.

Therefore, this invention is excellent in long-term storage stability, and can improve the cycling characteristics and safety of the secondary battery obtained, the aqueous binder composition for secondary battery positive electrodes, the slurry composition for secondary battery positive electrodes using this binder composition, a secondary battery positive electrode, and It is an object to provide a secondary battery.

Therefore, as a result of the present inventors' investigation, by containing the isothiazoline-based compound and the chelate compound in a specific amount of a composition containing a binder of a specific composition, the long-term storage stability of the binder composition is good and the secondary battery obtained It was found that the cycle characteristics and safety of the can be improved.

The gist of the present invention for the purpose of solving such a problem is as follows.

(1) 0.001-1.0 mass part of isothiazoline type compounds with respect to the binder which has a (meth) acrylic acid ester monomeric unit, the vinyl monomeric unit which has an acidic group, and the (alpha), (beta)-unsaturated nitrile monomeric unit, and 100 mass parts of this binder. And the aqueous binder composition for secondary battery positive electrodes containing 0.001-1.0 mass part of chelate compounds.

(2) The aqueous binder composition for secondary battery positive electrodes as described in (1) in which the said binder further contains the other monomeric unit copolymerizable with each said monomeric unit, and that other monomeric unit is a monomeric unit which has a crosslinkable group.

(3) The aqueous binder composition for secondary battery positive electrodes as described in (1) or (2) whose vinyl monomeric unit which has the said acidic group is a vinyl monomeric unit which has a carboxylic acid group.

(4) The secondary battery according to any one of (1) to (3), wherein the chelate compound is selected from the group consisting of an aminocarboxylic acid chelate compound, a phosphonic acid chelate compound, gluconic acid, citric acid, malic acid, and tartaric acid. Aqueous binder composition for positive electrodes.

(5) The aqueous binder composition for secondary battery positive electrodes as described in any one of (1)-(4) containing 0.001-1.0 mass part of pyrithione compounds with respect to 100 mass parts of said binders.

(6) The slurry composition for secondary battery positive electrodes containing the aqueous binder composition for secondary battery positive electrodes in any one of said (1)-(5), and a positive electrode active material.

(7) The secondary battery positive electrode formed by forming the positive electrode active material layer which consists of a slurry composition for secondary battery positive electrodes as described in said (6) on an electrical power collector.

(8) A secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte solution, wherein the positive electrode is a secondary battery positive electrode according to (7).

According to the present invention, a binder having a (meth) acrylic acid ester monomer unit, a vinyl monomer unit having an acidic group, and an α, β-unsaturated nitrile monomer unit, a specific amount of isothiazoline-based compound with respect to 100 parts by mass of the binder, Long-term storage stability of a binder composition becomes favorable by using the aqueous binder composition for secondary battery negative electrodes containing a specific amount of chelate compound. In addition, the chelate compound in the binder composition traps transition metal ions eluted in the electrolyte during charging and discharging, thereby preventing the degradation of cycle characteristics (particularly high temperature cycle characteristics) and safety of secondary batteries caused by the transition metal ions. can do. In addition, the secondary battery positive electrode using the binder composition does not deteriorate well even after repeated charging and discharging, thereby increasing the life of the secondary battery.

Hereinafter, (1) the aqueous binder composition for secondary battery positive electrodes, the slurry composition for (2) secondary battery positive electrodes, (3) secondary battery positive electrode, and (4) secondary battery are demonstrated one by one.

(1) secondary battery For positive electrode  Waterborne binder composition

The aqueous binder composition for secondary battery positive electrodes of this invention contains a binder, a specific amount of isothiazoline type compound, and a specific amount of chelate compound.

The binder has a (meth) acrylic acid ester monomer unit, a vinyl monomer unit having an acidic group, and an α, β-unsaturated nitrile monomer unit.

The said (meth) acrylic acid ester monomeric unit is a polymer repeating unit obtained by superposing | polymerizing a (meth) acrylic acid ester monomer, the vinyl monomeric unit which has an acidic group is a polymer repeating unit obtained by superposing | polymerizing the vinyl monomer which has an acidic group, (alpha), (beta) The -unsaturated nitrile monomer unit is a polymer repeating unit obtained by polymerizing an α, β-unsaturated nitrile monomer. Moreover, the other monomeric unit copolymerizable with these mentioned later is a polymer repeating unit obtained by superposing | polymerizing the other monomer which can be copolymerized.

In addition, in this application, when it describes with "(meth) acryloyl", "(meth) acrylic acid", and "(meth) allyl", unless otherwise indicated, it is respectively acryloyl and / or meta "Cryloyl", "acrylic acid and / or methacrylic acid", and "allyl and / or methallyl" shall be shown.

As the (meth) acrylic acid ester monomer, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acryl Alkyl acrylates such as acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate and stearyl acrylate; methyl methacrylate, ethyl meth Acrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetrade And alkyl methacrylates such as silmethacrylate and stearyl methacrylate.

Among them, they bind to non-carbonyl oxygen atoms because they do not elute in the electrolyte and exhibit conductivity of lithium ions due to proper swelling to the electrolyte, and do not easily cross-link with the polymer in dispersing the active material. Heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, and lauryl acrylate which are C7-C13 alkyl acrylate ester of an alkyl group to mention are preferable, and non-carbonyl oxygen More preferably, octyl acrylate, 2-ethylhexyl acrylate, and nonyl acrylate having 8 to 10 carbon atoms of the alkyl group bonded to the atom.

Vinyl monomers having an acidic group is a vinyl monomer represents an acid, specifically, -COOH group (carboxylic acid group), a vinyl monomer, a vinyl monomer -OH group, -SO ₃ H with a (hydroxy group), a group having (a sulfonic acid group ), A vinyl monomer having a -PO ₃ H ₂ group, a vinyl monomer having a -PO (OH) (OR) group (R represents a hydrocarbon group), and a vinyl monomer having a lower polyoxyalkylene group, and a valence The vinyl monomer which produces | generates a carboxylic acid group by decomposition is mentioned.

As a vinyl monomer which has a carboxylic acid group, monocarboxylic acid, its derivative (s), dicarboxylic acid, these derivatives, etc. are mentioned. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid and crotonic acid. As monocarboxylic acid derivative, 2-ethylacrylic acid, isocrotonic acid, (alpha)-acetoxyacrylic acid, (beta) -trans- aryloxyacrylic acid, (alpha)-chloro- (beta) -E-methoxyacrylic acid, (beta)-diaminoacrylic acid, etc. are mentioned. Can be mentioned. Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, and the like. Examples of the dicarboxylic acid derivatives include methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloro maleic acid, dichloromaleic acid, and fluoromaleic acid, such as methyl allyl maleate, diphenyl maleic acid, nonyl maleate, and maleic acid maleic acid; Maleic acid monoesters such as dodecyl maleate, octadecyl maleate and fluoroalkyl maleate.

As a vinyl monomer which has a hydroxyl group, Ethylenic unsaturated alcohols, such as (meth) allyl alcohol, 3-butene-1-ol, 5-hexene-1-ol; 2-hydroxyethyl acrylate, 2-hydroxy acrylate; Propyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, maleic acid-di-2-hydroxyethyl, di-4-hydroxybutyl maleate, di-2-hydroxy itaconic acid Alkanol esters of ethylenically unsaturated carboxylic acids such as propyl; general formula CH ₂ = CR ¹ -COO- (C _n H _2n O) _m -H (m is an integer of 2 to 9, n is 2 to 4) Constant, R ¹ represents hydrogen or a methyl group); esters of polyalkylene glycol and (meth) acrylic acid; 2-hydroxyethyl-2 '-(meth) acryloyloxyphthalate, 2-hydroxyethyl- Mono (meth) acrylic acid esters of dihydroxy esters of dicarboxylic acids such as 2 ′-(meth) acryloyloxysuccinate; Vinyl ethers such as hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl ether; (meth) allyl-2-hydroxyethyl ether, (meth) allyl-2-hydroxypropyl ether, (meth) allyl-3- Hydroxypropyl ether, (meth) allyl-2-hydroxybutyl ether, (meth) allyl-3-hydroxybutyl ether, (meth) allyl-4-hydroxybutyl ether, (meth) allyl-6-hydroxy Mono (meth) allyl ethers of alkylene glycols such as hexyl ether; polyoxyalkylene glycol (meth) monoallyl ethers such as diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether; Halogen of (poly) alkylene glycols such as glycerin mono (meth) allyl ether, (meth) allyl-2-chloro-3-hydroxypropyl ether, (meth) allyl-2-hydroxy-3-chloropropyl ether And mono (meth) allyl ethers of hydroxy substituents;

Mono (meth) allyl ethers of polyhydric phenols such as eugenol and isoiogenol, and halogen substituents thereof; (meth) allyl-2-hydroxyethylthioether, (meth) allyl-2-hydroxypropylthioether, and the like. And (meth) allylthioethers of alkylene glycols.

Examples of the vinyl monomer having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth) allylsulfonic acid, styrenesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, and 3-aryloxy-2-hydroxypropanesulfonic acid. have.

-PO ₃ H ₂ group and / or -PO (OH) (OR) group of the vinyl monomer having the (R represents a hydrocarbon group) is, as a phosphoric acid-2-oxyethyl (meth) acrylate, methyl-2-phosphate (Meth) acryloyloxyethyl, ethyl phosphate ((meth) acryloyloxyethyl, etc. are mentioned.

As a vinyl monomer which has a lower polyoxyalkylene group, poly (alkylene oxide), such as poly (ethylene oxide), etc. are mentioned.

As a vinyl monomer which produces | generates a carboxylic acid group by hydrolysis, acid anhydrides of dicarboxylic acids, such as maleic anhydride, acrylic anhydride, methyl maleic anhydride, and dimethyl maleic anhydride, are mentioned.

Among these, the vinyl monomer which has a carboxylic acid group is preferable from the reason which is excellent in adhesiveness with respect to an electrical power collector, and is excellent in the dispersion stability of the slurry composition mentioned later, and the capture | acquisition ability of the transition metal eluted from the positive electrode active material, Among these, acrylic acid Monocarboxylic acid having 5 or less carbon atoms having carboxylic acid groups such as methacrylic acid and dicarboxylic acids having 5 or less carbon atoms having 2 carboxylic acid groups such as maleic acid, itaconic acid and fumaric acid are preferable. Furthermore, acrylic acid, methacrylic acid, and itaconic acid are preferable from the viewpoint of higher storage stability of the manufactured binder.

In this invention, an acrylonitrile, methacrylonitrile, the (alpha)-chloro acrylonitrile, the (alpha)-ethyl acrylonitrile etc. are mentioned as a monomer unit of the (alpha), (beta)-unsaturated nitrile monomer. Acrylonitrile and methacrylonitrile are preferable from the viewpoint of improving the mechanical strength and binding strength of the binder.

In the present invention, the binder has a (meth) acrylic acid ester monomer unit, a vinyl monomer unit having an acidic group, and an α, β-unsaturated nitrile monomer unit as essential components, but may further have other monomer units copolymerizable with these. .

As another monomer copolymerizable with these, the monomer which has a crosslinkable group (it may describe as a "crosslinkable group containing monomer" below), the carboxylic acid ester monomer which has a 2 or more carbon-carbon double bond, a halogen atom A containing monomer, a vinyl ester monomer, a vinyl ether monomer, a vinyl ketone monomer, a heterocyclic containing vinyl monomer, acrylamide, methacrylamide, etc. are mentioned. Especially, the monomer which has a crosslinkable group is preferable at the point which can make high the crosslinking density of a binder in small quantity, can lower electrolyte solution swelling property, and can improve the life characteristic of the secondary battery obtained as a result.

As a crosslinkable group containing monomer, the monofunctional monomer which has one olefinic double bond which has a heat crosslinkable crosslinkable group, and the polyfunctional monomer which has at least 2 olefinic double bond are mentioned.

The thermally crosslinkable crosslinkable group contained in the monofunctional monomer having one olefinic double bond includes at least one member selected from the group consisting of an epoxy group, an N-methylolamide group, an oxetanyl group, and an oxazoline group. A monomer can be mentioned. Among these, the monomer containing an epoxy group is more preferable at the point which crosslinking and control of a crosslinking density are easy.

As a monomer containing an epoxy group, the monomer containing a carbon-carbon double bond and an epoxy group, and the monomer containing a halogen atom and an epoxy group are mentioned.

As a monomer containing a carbon-carbon double bond and an epoxy group, Unsaturated glycidyl ether, such as vinylglycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, o-allylphenyl glycidyl ether; Such as monoepoxide, chlorofurene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5,9-cyclododecadiene Monoepoxides of dienes or polyenes; alkenylepoxides such as 3,4-epoxy-1-butene, 1,2-epoxy-5-hexene and 1,2-epoxy-9-decene; glycidylacryl Glycidyl methacrylate, glycidyl crotonate, glycidyl-4-heptenoate, glycidyl sorbate, glycidyl linoleate, glycidyl-4-methyl-3-penteno Glycides of unsaturated carboxylic acids such as acetate, glycidyl ester of 3-cyclohexene carboxylic acid, and glycidyl ester of 4-methyl-3-cyclohexene carboxylic acid Dill esters are mentioned.

As a monomer which has a halogen atom and an epoxy group, For example, epihalohydrin, such as epichlorohydrin, epibromohydrin, epiiodhydrin, epifluorohydrin, (beta) -methyl epichlorohydrin; p-chloro styrene oxide; dibromophenyl glycidyl ether is mentioned.

As a monomer containing an N-methylolamide group, (meth) acrylamide which has methylol groups, such as N-methylol (meth) acrylamide, is mentioned.

As a monomer containing an oxetanyl group, 3-((meth) acryloyloxymethyl) oxetane, 3-((meth) acryloyloxymethyl) -2-trifluoromethyloxetane, 3- ( (Meth) acryloyloxymethyl) -2-phenyloxetane, 2-((meth) acryloyloxymethyl) oxetane, 2-((meth) acryloyloxymethyl) -4-trifluoromethyl Oxetane etc. are mentioned.

Examples of the monomer containing an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl- 2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, etc. Can be mentioned.

Polyfunctional monomers having at least two olefinic double bonds include allyl acrylate or allyl methacrylate, ethylenediacrylate, ethylenedimethacrylate, trimethylolpropane-triacrylate, trimethylolpropane-methacrylate, Allyl or vinyl ether, tetraethylene glycol diacrylate, triallyl other than dipropylene glycol diallyl ether, polyglycol diallyl ether, triethylene glycol divinyl ether, hydroquinone diallyl ether, tetraallyloxy ethane, or polyfunctional alcohol Amines, trimethylolpropane-diallyl ether, methylenebisacrylamide and / or divinylbenzene.

Among these, since the crosslinking density is easy to improve and excellent in binding property and electrolyte resistance, the polyfunctional monomer which has at least 2 olefinic double bond is preferable, and also for the reason of the viewpoint of the improvement of a crosslinking density, and high copolymerizability. Allyl acrylate or allyl methacrylate is preferred.

Examples of the carboxylic acid ester monomer having two or more carbon-carbon double bonds include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane triacrylate.

Vinyl chloride and vinylidene chloride are mentioned as a halogen atom containing monomer.

Vinyl acetate, vinyl propionate, and a vinyl butyrate are mentioned as a vinyl ester monomer.

As a vinyl ether monomer, methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether are mentioned.

Examples of the vinyl ketone monomers include methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone.

Examples of the heterocyclic vinyl monomers include N-vinylpyrrolidone, vinylpyridine, vinylimidazole and the like.

As for the ratio of each monomer unit of the binder in this invention, (meth) acrylic acid ester monomeric unit becomes like this. Preferably it is 50-95 mass%, More preferably, it is 60-90 mass%, The vinyl monomer unit which has an acidic group is preferable. Preferably it is 0.1-10 mass%, More preferably, it is 1.0-7.0 mass%, The (alpha), (beta)-unsaturated nitrile monomeric unit becomes like this. Preferably it is 3-40 mass%, More preferably, it is 5-30 mass%, The other monomeric unit which can be copolymerized becomes like this. Preferably it is 0.05-47 mass%, More preferably, it is 0.1-37 mass%. Moreover, when using a crosslinkable group containing monomer as another monomer copolymerizable, the ratio of a crosslinkable group containing monomeric unit becomes like this. Preferably it is 0.05-2.0 mass%, More preferably, it is 0.1-1.0 mass%.

If a binder does not contain a (meth) acrylic acid ester monomeric unit, the flexibility of a binder will be impaired, and as a result, a pole plate will fall. Moreover, moderate swelling property with respect to electrolyte solution becomes low, and lithium ion conductivity also becomes low. When the ratio of the (meth) acrylic acid ester monomeric unit in a binder is the said range, the winding property and lithium ion conductivity of a pole plate can be ensured in the state which maintained flexibility.

If a binder does not contain the vinyl monomeric unit which has an acidic group, dispersion stability and slurry stability of a binder itself will fall, and also adhesiveness of a pole plate will fall. When the ratio of the vinyl monomer unit which has an acidic group in a binder is the said range, the dispersion stability of a binder, slurry stability, and adhesiveness of a pole plate can be improved.

When a binder does not contain the (alpha), (beta)-unsaturated nitrile monomeric unit, the mechanical strength of a binder and the adhesiveness of a pole plate fall, and the life characteristic (cycle characteristic) of the secondary battery obtained as a result falls. Moreover, when the ratio of the (alpha), (beta)-unsaturated nitrile monomeric unit in a binder is the said range, the adhesiveness of a pole plate improves and the life characteristic (cycle characteristic) of the secondary battery obtained as a result improves.

The aqueous binder composition for secondary battery positive electrodes of the present invention contains a specific amount of isothiazoline compound. Since the binder composition of this invention can suppress the propagation of fungi by containing a specific amount of isothiazoline type-compounds, generation | occurrence | production of off-flavor and thickening of this binder composition can be prevented, and long-term storage stability This is excellent.

An isothiazoline type compound is a compound known as a general preservative, and is represented by following structural formula (1).

[Formula 1]

(In formula, Y represents hydrogen or the hydrocarbon group which may be substituted, X <^1> and X <^2> respectively represent a hydrogen atom, a halogen atom, or a C1-C6 alkyl group, respectively. Moreover, X <^1> , X <^2> is common You may form an aromatic ring, and X <^1> and X <^2> may be the same respectively and may differ.)

First, the isothiazoline type compound represented by said structural formula (1) is demonstrated.

In the structural formula (1), Y represents a hydrogen atom or a hydrocarbon group which may be substituted. As a substituent of the hydrocarbon group which may be substituted by Y, for example, a hydroxyl group, a halogen atom (for example, chlorine, fluorine, bromine, iodine etc.), a cyano group, an amino group, a carboxyl group, alkoxy of 1 to 4 carbon atoms Groups (e.g., methoxy groups, ethoxy groups, etc.), aryloxy groups having 6 to 10 carbon atoms (e.g., phenoxy groups), alkylthio groups having 1 to 4 carbon atoms (e.g., methylthio groups, ethylthio groups, etc.) ) And an arylthio group having 6 to 10 carbon atoms (for example, a phenylthio group). In the said substituent, a halogen atom and a C1-C4 alkoxy group are preferable. These substituents may substitute the hydrogen of the said hydrocarbon group in the range of 1-5, Preferably 1-3, and the said substituent may be same or different, respectively.

As this hydrocarbon group of the hydrocarbon group which may be substituted by Y, a C1-C10 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, a C3-C10 cycloalkyl group, carbon number 6-14 aryl group etc. are mentioned. In the said hydrocarbon group, a C1-C10 alkyl group and a C3-C10 cycloalkyl group are preferable, and a C1-C10 alkyl group is more preferable.

Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, Octyl group, isooctyl group, sec-octyl group, tert-octyl group, nonyl group and decyl group. In these alkyl groups, C1-C3 alkyl groups, such as a methyl group and an ethyl group, for example, C7-10 alkyl groups, such as an octyl group and a tert-octyl group, are more preferable, and a C1-C3 alkyl group is more preferable, for example. Is more preferable.

As said C2-C6 alkenyl group, a vinyl group, an allyl group, isopropenyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1- propenyl group, etc. are mentioned, for example. In the said alkenyl group, a vinyl group and an allyl group are preferable.

As said C2-C6 alkynyl group, an ethynyl group, 1-propynyl group, 2-propynyl group, butynyl group, a pentynyl group, etc. are mentioned, for example. In the said alkynyl group, an ethynyl group and a propynyl group are preferable.

As said C3-C10 cycloalkyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group etc. are mentioned, for example. In the said cycloalkyl group, a cyclopentyl group and a cyclohexyl group are preferable.

As said C6-C14 aryl group, a phenyl group, a naphthyl group, anthryl group, a phenanthryl group, etc. are mentioned, for example. In the said aryl group, a phenyl group is preferable.

As mentioned above, although various things are mentioned as a hydrocarbon group which may be substituted by Y, Among these hydrocarbon groups, a methyl group and an octyl group are more preferable, and a methyl group is still more preferable.

In the structural formula (1), X ¹ and X ² each represent a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may be the same or different.

As said halogen atom, fluorine, chlorine, bromine, and iodine are mentioned, for example, A chlorine atom is preferable in these.

Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group and pentyl group. In the said alkyl group, C1-C4 alkyl groups, such as a methyl group, an ethyl group, and a propyl group, are preferable, for example. Among the substituents described above, X ¹ is more preferably a hydrogen atom or a chlorine atom, and more preferably a chlorine atom. Moreover, as X <^2> , a hydrogen atom or a chlorine atom is more preferable, and a hydrogen atom is further more preferable.

As a specific example of the isothiazoline type compound represented by said structural formula (1), for example, 5-chloro- 2-methyl- 4-isothiazolin-3-one, 2-methyl- 4-isothiazoline-3 -One, 2-n-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 2-ethyl-4-isothiazoline 3-one, 4,5-dichloro-2-cyclohexyl-4-isothiazolin-3-one, 5-chloro-2-ethyl-4-isothiazolin-3-one, 5-chloro-2- t-octyl-4-isothiazolin-3-one etc. are mentioned. Among these compounds, 5-chloro-2-methyl-4-isothiazolin-3-one (hereinafter sometimes referred to as "CIT"), 2-methyl-4-isothiazolin-3-one ( The following may be referred to as "MIT"), 2-n-octyl-4-isothiazolin-3-one (hereinafter may be referred to as "OIT"), 4,5-dichloro-2- n-octyl-4-isothiazolin-3-one is preferable, and 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one are more preferable. desirable.

The following structural formula (2) shows the case where in the above structural formula (1), X ¹ and X ² jointly form an aromatic ring, a benzene ring is formed.

(2)

(In formula, Y is the same as that of structural formula (1), X <^3> -X <^6> is a hydrogen atom, a halogen atom, a hydroxyl group, a cyano group, an amino group, a carboxyl group, a C1-C4 alkyl group, or C1-C4). Each alkoxy group)

In said structural formula (2), X <^3> -X <^6> represents a hydrogen atom, a hydroxyl group, a halogen atom (for example, chlorine, fluorine, bromine, iodine, etc.), a cyano group, an amino group, a carboxyl group, C1-C4 Alkyl group (for example, methyl group, ethyl group, propyl group, etc.), C1-C4 alkoxy group (for example, methoxy group, ethoxy group etc.), etc. are mentioned, Among these, a halogen atom and a C1-C4 group are mentioned. Alkyl groups are preferred. These X <^3> -X <^6> may be the same respectively and may differ.

As an isothiazoline type compound represented by the said Structural formula (2), 1, 2- benzisothiazolin-3-one (it may be represented by "BIT" hereafter), N-methyl- 1, 2- benz Isothiazolin-3-one etc. are mentioned.

These isothiazoline type compounds can be used individually or in combination of 2 or more types. In the long-term storage stability of the aqueous binder composition and battery characteristics (cycle life) using the binder composition, among these, 1, 2-benzisothiazolin-3-one is particularly preferable.

In this invention, content of the isothiazoline type compound with respect to the binder of the specific composition containing the said specific monomeric unit is the range of 0.001-1.0 mass part with respect to 100 mass parts (solid content conversion) of the binder, Preferably Is 0.005-0.5 mass part, More preferably, it is 0.01-0.1 mass part. When content of an isothiazoline type-compound is less than 0.001 mass part, propagation of the fungus in the composition of the binder of the said specific composition is not suppressed, and long-term storage stability of this binder composition falls. Moreover, with the propagation of the fungus in the same binder composition, a binder composition is modified and the viscosity of a binder composition increases. As a result, while handling a binder composition becomes difficult, peeling strength falls. On the other hand, when content of an isothiazoline type-compound exceeds 1.0 mass part, the cycling characteristics of the secondary battery using this binder composition will fall irrespective of a bactericidal effect.

In addition, in this invention, in the range which does not prevent the effect of this invention, it does not prevent the use of preservatives other than the said isothiazoline type compound at all.

The aqueous binder composition for secondary battery positive electrodes of the present invention contains a specific amount of chelate compound. Since the binder composition of the present invention can capture the transition metal ions eluted in the electrolytic solution during charging and discharging of the secondary battery using the binder composition by containing a specific amount of the chelate compound, The deterioration of cycle characteristics and safety can be prevented.

The chelate compound is not particularly limited, but is preferably selected from the group consisting of an aminocarboxylic acid chelate compound, a phosphonic acid chelate compound, gluconic acid, citric acid, malic acid and tartaric acid. Among these, chelate compounds which can selectively capture transition metal ions without trapping lithium ions are used, and in particular, the following aminocarboxylic acid chelate compounds and phosphonic acid chelate compounds are preferably used.

Examples of aminocarboxylic acid chelate compounds include ethylenediaminetetraacetic acid (hereinafter referred to as "EDTA"), nitrilotriacetic acid (hereinafter referred to as "NTA"), trans-1,2 -Diaminocyclohexane tetraacetic acid (hereinafter may be referred to as "CyDTA"), diethylene-triamine pentacetic acid (hereinafter may be referred to as "DTPA"), bis- (aminoethyl) glycol ether- N, N, N ', N'-tetraacetic acid (hereinafter sometimes referred to as "EGTA"), N- (2-hydroxyethyl) ethylenediamine-N, N', N'-triacetic acid (hereinafter It is preferable to select from the group which consists of "HEDTA" in this case, and dihydroxyethylglycine (it may be represented by "DHEG" hereafter)).

As the phosphonic acid chelate compound, 1-hydroxyethane-1,1-diphosphonic acid (hereinafter sometimes referred to as "HEDP") is preferable.

In this invention, content of the chelate compound with respect to the binder of the specific composition containing the said specific monomeric unit is the range of 0.001-1.0 mass part with respect to 100 mass parts (solid content conversion) of the binder, Preferably it is 0.005-- 0.5 mass part, More preferably, it is 0.01-0.3 mass part. If the content of the chelating compound is less than 0.001 parts by mass, the trapping ability of the transition metal ions is insufficient, so that the cycle characteristics of the secondary battery decrease. Moreover, when it exceeds 1.0 mass part, it will not be able to hope for the transition metal trapping effect more, and the cycling characteristics of the secondary battery using this binder composition may fall.

Moreover, in the aqueous binder composition for secondary battery positive electrodes of this invention, with respect to 100 mass parts (solid content conversion) mentioned above, Preferably it is 0.001-1.0 mass part, More preferably, it is 0.005-0.5 mass part, Especially preferably, It is preferable that 0.01-0.1 mass part pyrithione compound is contained.

By the way, in the substance used as an industrial antimicrobial composition, antimicrobial effect and safety are incompatible, and the substance excellent in antimicrobial power tends to have a problem in safety, such as having mutagenicity.

Among the isothiazoline-based compounds, CIT has a high antibacterial effect, but it is known that there is a safety problem that it is mutagenic or easily prone to allergy. Moreover, when pH in a system becomes 9 or more, the antimicrobial activity fall large. Although MIT has high safety, its antibacterial effect is slightly inferior to that of CIT, and similarly to CIT, MIT is alkaline and its stability is lowered. Although BIT is relatively high in stability, its immediate effectiveness is slightly low, and when the pH in the system reaches 9 or more, the antibacterial activity gradually decreases.

Since the pyrithione compound is stable even in alkali, by using it together with an isothiazoline compound, the antiseptic performance effect can be extended even under alkaline conditions, and a high antibacterial effect can be obtained by a synergistic effect.

Examples of the pyrithione compound include alkali metal salts such as sodium, potassium and lithium; monovalent salts such as ammonium salts, and polyvalent salts such as calcium, magnesium, zinc, copper, aluminum and iron. Water-soluble monovalent salts are preferable. In particular, alkali metal salts such as sodium, potassium, lithium and the like are preferable from the viewpoint of the versatility and cycle characteristics of the secondary battery. Specific examples of preferred pyrithione compounds include sodium pyrithione, potassium pyrithione and lithium pyrithione. Among these, sodium pyrithione is preferable because of its high solubility.

The aqueous binder composition for secondary battery positive electrodes of this invention is a composition which can bind together the electrode active material mentioned later and the electrically conductive agent added as needed, and the solution which the binder which is a polymer particle which has binding force melt | dissolved or disperse | distributed in an aqueous solvent, or You may use what filtered the dispersion liquid (Hereinafter, these may be collectively described as "the aqueous dispersion liquid containing a binder.").

(Production of Aqueous Dispersion Containing Binder)

The aqueous dispersion liquid containing the binder which consists of a polymer is manufactured by superposing | polymerizing the monomer composition containing the said monomer in an aqueous solvent, for example. As for the ratio of each monomer in the monomer composition in the process of obtaining the aqueous dispersion liquid containing the binder which consists of a polymer, (meth) acrylic acid ester monomeric unit becomes like this. Preferably it is 50-95 mass%, More preferably, it is 60-90 mass% Preferably, the vinyl monomeric unit which has an acidic group is 0.1-10 mass%, More preferably, it is 1.0-7.0 mass%, The (alpha), (beta)-unsaturated nitrile monomeric unit becomes like this. Preferably it is 3-40 mass%, More preferably, Is 5-30 mass%, and the other monomeric unit copolymerizable with these becomes like this. Preferably it is 0.05-47 mass%, More preferably, it is 0.1-37 mass%. In addition, when using a crosslinkable group containing monomer as another monomer copolymerizable, the ratio of a crosslinkable group containing monomeric unit becomes like this. Preferably it is 0.05-2.0 mass%, More preferably, it is 0.1-1.0 mass%.

In this specification, an aqueous solvent means water or a hydrophilic solvent. As an aqueous solvent, if a binder can be disperse | distributed, it will not specifically limit, Usually, the boiling point in normal pressure is selected from the dispersion medium of 80-350 degreeC, Preferably it is 100-300 degreeC. In addition, the number in () after a dispersion medium name is the boiling point in normal pressure (unit degreeC), and the decimal point is the value rounded off or rounded off. For example, as a ketone, diacetone alcohol (169) and (gamma) -butyrolactone (204); as alcohol, ethyl alcohol (78), isopropyl alcohol (82), normal propyl alcohol (97); glycol As examples, ethylene glycol (193), propylene glycol (188), diethylene glycol (244); glycol ethers include propylene glycol monomethyl ether (120), methyl cellosolve (124), and ethyl cellosolve ( 136), ethylene glycol tertiary butyl ether (152), butyl cellosolve (171), 3-methoxy-3methyl-1-butanol (174), ethylene glycol monopropyl ether (150), diethylene glycol monobutyl Ether (230), triethylene glycol monobutyl ether (271), dipropylene glycol monomethyl ether (188); 1,3-dioxolane (75), 1,4-dioxolane (101) ) And tetrahydrofuran (66). Especially, water is the most preferable from a viewpoint that it is not flammable and the dispersion of a binder is easy to be obtained easily. Moreover, you may use water as a main solvent, and mix and use aqueous solvents other than the water described above in the range which can ensure the dispersion state of a binder.

The polymerization method is not particularly limited, and any method such as a solution polymerization method, suspension polymerization method, bulk polymerization method or emulsion polymerization method can be used. As polymerization reaction, ionic polymerization, radical polymerization, a living radical polymerization, etc. are mentioned. Emulsification among them from the viewpoint of production efficiency, such that the high molecular weight is well obtained, the polymer is obtained in the state of being dispersed in water as it is, and the process of redispersion is unnecessary and can be used as it is for the slurry composition production for the secondary battery positive electrode. Most preferred is the polymerization method.

The emulsion polymerization method is a conventional method, for example, the method described in "Experimental Chemistry Lecture" Vol. 28, (Publisher: Maruzen, Japan Chemical Society), that is, airtight with a stirrer and a heating device. Additives such as water, a dispersant, an emulsifier, a crosslinking agent, an initiator, and a monomer are added to a container so as to have a predetermined composition, followed by stirring to emulsify the monomer in water, and the temperature is raised while stirring to initiate polymerization. Or after emulsifying the said composition, it puts into a closed container and is the method of starting reaction similarly.

An emulsifier, a dispersing agent, a polymerization initiator, etc. are generally used in these polymerization methods, The usage-amount may be sufficient as it is generally used. Moreover, in polymerization, it is also possible to employ | adopt seed particle | grains (seed polymerization).

Although superposition | polymerization temperature and superposition | polymerization time can be arbitrarily selected according to the method of emulsion polymerization, the kind of polymerization initiator to be used, etc., Usually, polymerization temperature is about 30 degreeC or more and polymerization time is about 0.5 to 30 hours. Additives, such as amines, can also be used as a polymerization aid. Further, in the aqueous dispersion of the polymer particles obtained by these methods, alkali metal (Li, Na, K, Rb, Cs) hydroxides, ammonia, inorganic ammonium compounds (NH ₄ Cl, etc.), organic amine compounds (ethanolamine, diethylamine Etc.) can be adjusted so as to be in a range of pH 5 to 10, preferably pH 5 to 9 by adding a basic aqueous solution in which the etc. are dissolved. Especially, pH adjustment by alkali metal hydroxide is preferable in order to improve binding property (fill strength) of a binder composition, an electrical power collector, and an active material.

The above-mentioned binder may be a composite polymer particle composed of two or more kinds of polymers. The composite polymer particles are also polymerized by a conventional method for at least one monomer component, followed by addition of another at least one monomer component, followed by polymerization by a conventional method (two-stage polymerization method) or the like. You can get it.

As a polymerization initiator used for superposition | polymerization, a lauroyl peroxide, diisopropyl peroxy dicarbonate, di-2-ethylhexyl peroxy dicarbonate, t-butylperoxy pivalate, 3,3,5-trimethyl hexa, for example Organic peroxides, such as a noyl peroxide, Azo compounds, such as (alpha), (alpha) '-azobisisobutyronitrile, ammonium persulfate, potassium persulfate, etc. are mentioned.

Moreover, in the said superposition | polymerization, it is preferable to add a chain transfer agent. As a chain transfer agent, alkyl mercaptan is preferable, and specifically, n-butyl mercaptan, t-butyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl Mercaptan, t-dodecyl mercaptan, and n-stearyl mercaptan. Especially, n-octyl mercaptan and t-dodecyl mercaptan are preferable from a viewpoint that polymerization stability is favorable.

Moreover, you may use together another chain transfer agent with the said alkyl mercaptan. Examples of the chain transfer agent that may be used in combination include α-methylstyrene dimer, terpinolene, allyl alcohol, allylamine, sodium allyl sulfonate (potassium), sodium metaallyl sulfonate (potassium), and the like. The usage-amount of the said chain transfer agent is not specifically limited in the range which does not prevent the effect of this invention.

50-500 nm is preferable and, as for the number average particle diameter of the binder in an aqueous dispersion liquid, 70-400 nm is more preferable. Since the number average particle diameter of a binder exists in the said range, the intensity | strength and flexibility of the positive electrode obtained become favorable. Presence of a polymer particle can be easily measured by a transmission electron microscope method, a Coulter counter, a laser diffraction scattering method, etc.

It is preferable that the glass transition temperature of a binder is 40 degrees C or less, More preferably, it is -75- + 30 degreeC, More preferably, it is -55- + 20 degreeC, Most preferably, it is -35- + 15 degreeC. When the glass transition temperature of a binder is the said range, characteristics, such as the softness | flexibility of a positive electrode, binding property, and winding property, adhesiveness of a positive electrode active material and an electrical power collector, are highly balanced, and are preferable.

The binder may be a binder made of polymer particles having a core shell structure obtained by polymerizing the monomers in stages.

(Production of Aqueous Binder Composition for Secondary Battery Positive Electrode)

The aqueous binder composition for secondary battery positive electrodes is 0.001 to 1.0 parts by mass, preferably 0.005 to 0.5 parts by mass, with respect to 100 parts by mass of the binder in the aqueous dispersion (hereinafter sometimes referred to as "binder dispersion"), More preferably, it is prepared by adding and mixing 0.01 to 0.1 parts by mass of the isothiazoline compound and 0.001 to 1.0 parts by mass, preferably 0.005 to 0.5 parts by mass, more preferably 0.01 to 0.3 parts by mass of the chelate compound. . In addition, at the time of preparation of the aqueous dispersion liquid containing the binder mentioned above, the said chelate compound is added, the said monomer is superposed | polymerized in presence of a chelate compound, after that, unreacted monomer is removed by cooling under reduced pressure distillation, and after cooling The aqueous binder composition for secondary battery positive electrodes can also be produced by adding and mixing the specific amount of the isothiazoline compound.

In this invention, the said chelate compound may be added at the time of removing an unreacted monomer by heat-pressure distillation, and may be added simultaneously at the time of addition of an isothiazoline type compound. Moreover, you may add the said chelating agent in the form of a sodium salt, potassium salt, and ammonium salt.

The method of mixing an isothiazoline type compound and a chelate compound in the aqueous dispersion liquid of a polymer is not specifically limited, For example, the method of using mixing apparatuses, such as a stirring type, shaking type, and rotary type, is mentioned. Moreover, the method using the dispersion kneading apparatuses, such as a homogenizer, a ball mill, a sand mill, a roll mill, a planetary mixer, and a planetary kneader, is mentioned.

Moreover, an additive can be added to the binder composition of this invention in order to improve applicability | paintability or to improve charge / discharge characteristic. These additives include cellulose polymers such as carboxymethyl cellulose, methyl cellulose and hydroxypropyl cellulose, polyacrylates such as sodium polyacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, and acrylic acid-vinyl alcohol copolymers. And methacrylic acid-vinyl alcohol copolymers, maleic acid-vinyl alcohol copolymers, modified polyvinyl alcohols, polyethylene glycols, ethylene-vinyl alcohol copolymers, and polyvinyl acetate partial saponates. The use ratio of these additives is with respect to the total solid content mass of a binder composition, Preferably it is less than 300 mass%, More preferably, it is 30 mass% or more and 250 mass% or less, Especially preferably, they are 40 mass% or more and 200 mass% or less. . If it is this range, the secondary battery positive electrode excellent in smoothness can be obtained. These additives can be added to the slurry composition for secondary battery positive electrodes of this invention mentioned later other than the method of adding to a binder composition.

(2) secondary battery For positive electrode Slurry  Composition

The slurry composition for secondary battery positive electrodes of this invention contains the said aqueous binder composition for secondary battery positive electrodes, and a positive electrode active material. Below, the aspect which uses the slurry composition for secondary battery positive electrodes of this invention as a slurry composition for lithium ion secondary battery positive electrodes is demonstrated.

(Positive electrode active material)

As the positive electrode active material, an active material which can dope and undo lithium ions is used, and is classified roughly into an inorganic compound and an organic compound.

As a positive electrode active material which consists of inorganic compounds, transition metal oxide, transition metal sulfide, lithium containing composite metal oxide of lithium and a transition metal, etc. are mentioned. As the transition metal, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo and the like are used.

As the transition metal oxide, MnO, MnO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , Cu ₂ V ₂ O ₃ , amorphous V ₂ OP ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O It includes _13, etc., and among them are preferable _{MnO, V 2 O 5, V} 6 O 13, TiO 2 from the cycle stability and capacity. Examples of the transition metal sulfides include TiS ₂ , TiS ₃ , amorphous MoS ₂ , FeS, and the like. As a lithium containing composite metal oxide, the lithium containing composite metal oxide which has a layered structure, the lithium containing composite metal oxide which has a spinel structure, the lithium containing composite metal oxide which has an olivine type structure, etc. are mentioned.

Lithium-containing composite metal oxides having a layered structure include lithium-containing cobalt oxide (LiCoO ₂ ), lithium-containing nickel oxide (LiNiO ₂ ), lithium composite oxide of Co-Ni-Mn, lithium composite oxide of Ni-Mn-Al, Ni And lithium composite oxides of -Co-Al. A lithium-containing composite metal oxide having a spinel structure lithium manganese oxide (LiMn ₂ O ₄₎ and the substituting a part of Mn with other transition metal _{Li [Mn 3/2 M 1} /2] O 4 ( where M, Cr , Fe, Co, Ni, Cu and the like). Examples of the lithium-containing composite metal oxide having an olivine-type structure include Li _X MPO ₄ (wherein M is Mn, Fe, Co, Ni, Cu, Mg, Zn, V, Ca, Sr, Ba, Ti, Al, and Si). And an olivine-type lithium phosphate compound represented by at least one selected from B, and Mo, 0 ≦ X ≦ 2).

As the organic compound, for example, a conductive polymer such as polyacetylene or poly-p-phenylene may be used. The iron oxide, which lacks electrical conductivity, may be used as an electrode active material covered with a carbon material by allowing a carbon source material to be present during reduction firing. In addition, these compounds may be partially substituted with elements. The positive electrode active material may be a mixture of the inorganic compound and the organic compound.

The volume average particle diameter of a positive electrode active material is 1-50 micrometers normally, Preferably it is 2-30 micrometers. When the particle diameter is in the above range, the amount of the binder composition for the positive electrode when preparing the slurry composition for the positive electrode can be reduced, the drop of the battery capacity can be suppressed, and the slurry composition for the positive electrode can be applied. It becomes easy to prepare at the viscosity suitable for, and a uniform electrode can be obtained.

In the slurry composition for secondary battery positive electrodes of the present invention, the total content of the positive electrode active material and the binder composition is preferably 10 to 90 parts by mass, and more preferably 30 to 80 parts by mass with respect to 100 parts by mass of the slurry composition. to be. Moreover, content (solid content equivalency) of the binder composition with respect to the total amount of a positive electrode active material becomes like this. Preferably it is 0.1-5 mass parts with respect to 100 mass parts of total amounts of a positive electrode active material, More preferably, it is 0.5-2 mass parts. When the total content of the positive electrode active material and the binder composition in the slurry composition and the content of the binder composition are within the above ranges, the viscosity of the slurry composition for secondary battery positive electrodes obtained is optimized, and coating can be performed smoothly. This does not become high and sufficient adhesive strength is obtained. As a result, peeling of the binder composition from the positive electrode active material in a pole plate press process can be suppressed.

(Dispersion medium)

In the present invention, water is used as the dispersion medium. In this invention, as long as it is a range which does not inhibit the dispersion stability of a binder composition, you may use what mixed the hydrophilic solvent with water as a dispersion medium. Examples of the hydrophilic solvent include methanol, ethanol, N-methylpyrrolidone and the like, and are preferably 5% by mass or less with respect to water.

(Conductive agent)

In the slurry composition for secondary battery positive electrodes of this invention, it is preferable to contain a electrically conductive agent. As the conductive agent, conductive carbon such as acetylene black, Ketjen black, carbon black, graphite, vapor grown carbon fiber, and carbon nanotube can be used. By containing a electrically conductive agent, the electrical contact of positive electrode active materials can be improved, and when using for a secondary battery, a discharge rate characteristic can be improved. Content of the electrically conductive agent in a slurry composition becomes like this. Preferably it is 1-20 mass parts, More preferably, it is 1-10 mass parts with respect to 100 mass parts of total amounts of a positive electrode active material.

(Thickener)

In the slurry composition for secondary battery positive electrodes of this invention, it is preferable to contain a thickener. Examples of the thickener include cellulose-based polymers such as carboxymethyl cellulose, methyl cellulose and hydroxypropyl cellulose and their ammonium salts and alkali metal salts; (modified) poly (meth) acrylic acid and their ammonium salts and alkali metal salts; (modified) polyvinyl Polyvinyl alcohols such as copolymers of alcohol, acrylic acid or acrylate and vinyl alcohol, maleic anhydride or copolymer of maleic acid or fumaric acid and vinyl alcohol; polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, modified polyacrylic acid, Oxidized starch, phosphate starch, casein, various modified starches, etc. are mentioned.

As for the compounding quantity of a thickener, 0.5-1.5 mass parts is preferable with respect to 100 mass parts of positive electrode active materials. If the compounding quantity of a thickener is the said range, coatability and adhesiveness with an electrical power collector are favorable. In the present invention, "(modified) poly" means "unmodified poly" or "modified poly", and "(meth) acryl" means "acryl" or "methacryl".

In addition to the above components, the slurry composition for secondary battery positive electrodes may further contain other components such as electrolyte additives having functions such as reinforcing materials, leveling agents, and electrolyte solution decomposition suppression, or may be contained in secondary battery positive electrodes described below. They are not particularly limited as long as they do not affect the cell reaction.

As the reinforcing material, various inorganic and organic spherical, plate, rod-like or fibrous fillers can be used. By using a reinforcing material, a strong and flexible positive electrode can be obtained, and excellent long-term cycle characteristics can be exhibited. Content of the reinforcing material in a slurry composition is 0.01-20 mass parts normally with respect to 100 mass parts of total amounts of a positive electrode active material, Preferably it is 1-10 mass. By being included in the above range, high capacity and many load characteristics can be exhibited.

As a leveling agent, surfactant, such as an alkyl type surfactant, a silicone type surfactant, a fluorine type surfactant, and a metal type surfactant is mentioned. By mixing a leveling agent, the cratering which arises at the time of coating can be prevented, or smoothness of a positive electrode can be improved. Content of the leveling agent in a slurry composition becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of total amounts of a positive electrode active material. When the leveling agent is in the above range, the productivity, smoothness and battery characteristics at the time of producing the positive electrode are excellent. By containing surfactant, dispersibility, such as a positive electrode active material in a slurry composition, can be improved, and also the smoothness of the positive electrode obtained by it can be improved.

As the electrolyte solution additive, vinylene carbonate or the like used in the slurry composition and in the electrolyte solution can be used. Content of the electrolyte solution additive in a slurry composition becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of total amounts of a positive electrode active material. When electrolyte solution additive is the said range, it is excellent in cycling characteristics and high temperature characteristics. In addition, nano fine particles, such as fumed silica and fumed alumina, are mentioned. By mixing nanoparticles, the thixotropy of a slurry composition can be controlled and the leveling property of the positive electrode obtained by it can be improved. Content of the nanoparticles in a slurry composition becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of total amounts of a positive electrode active material. When nanoparticles are in the said range, it is excellent in slurry stability and productivity, and shows high battery characteristics.

(Manufacture of the slurry composition for secondary battery positive electrodes)

The slurry composition for secondary battery positive electrodes is obtained by mixing the said binder composition, a positive electrode active material, and the electrically conductive agent used as needed. The quantity of the dispersion medium used when preparing this slurry composition is the quantity which solid content concentration of a slurry composition is 1-50 mass% normally, Preferably it becomes the range of 5-50 mass%. When the solid content concentration is in this range, it is preferable because the binder composition is uniformly dispersed.

Although the mixing method is not specifically limited, For example, the method of using mixing apparatuses, such as stirring, agitation, and rotation, is mentioned. Moreover, the method using the dispersion kneading apparatuses, such as a homogenizer, a ball mill, a sand mill, a roll mill, a planetary mixer, and a planetary kneader, is mentioned.

The viscosity of the slurry composition for secondary battery positive electrodes is 10-3, 000 mPa * s normally at room temperature, Preferably it is 30-1,500 mPa * s, More preferably, it is the range of 50-1,000 mPa * s. When the viscosity of a slurry composition exists in this range, productivity of the composite particle mentioned later can be raised. Moreover, the higher the viscosity of the slurry composition, the larger the spray droplets and the larger the weight average particle diameter of the composite particles to be obtained.

(3) secondary battery Positive

The secondary battery positive electrode of this invention forms the positive electrode active material layer which consists of the slurry composition for secondary battery positive electrodes of this invention on a collector.

(Method for producing secondary battery positive electrode)

The manufacturing method of the secondary battery positive electrode of this invention is not specifically limited. Specifically, (I) the method of sheet-molding the said slurry composition, the obtained sheet | seat is laminated | stacked on an electrical power collector, and a positive electrode active material layer is formed (sheet forming method), (II) the said slurry composition is at least single side | surface of an electrical power collector, Preferably, both surfaces are coated and dried to form a positive electrode active material layer (wet molding method), and (III) composite particles are prepared from the slurry composition, which is supplied onto a current collector and sheet molded to form a positive electrode active material layer. The method (dry molding method) etc. which form this can be mentioned. Among these, the (II) wet molding method or the (III) dry molding method is preferable. (II) The wet molding method is excellent in the production efficiency of a secondary battery positive electrode, and the (III) dry molding method is excellent at the point which can increase the capacity | capacitance of the secondary battery positive electrode obtained, and can also reduce internal resistance.

(II) In the wet molding method, the method of applying the slurry composition on the current collector is not particularly limited. For example, methods, such as a doctor blade method, a dip method, the reverse roll method, the direct roll method, the gravure method, the extrusion method, and the bristles application method, are mentioned.

As a drying method, the drying method by irradiation with warm air, hot air, low humidity wind, vacuum drying, (far) infrared rays, an electron beam, etc. are mentioned, for example. Drying time is 5-30 minutes normally, and drying temperature is 40-180 degreeC normally.

The composite grain | particle in (III) dry molding method shows the particle | grains which the binder composition contained in the said slurry composition, the positive electrode active material, etc. integrated. By forming a positive electrode active material layer using a composite grain | particle, while the peeling strength of the secondary battery positive electrode obtained can be made higher, internal resistance can be reduced.

The composite grain | particle used preferably for this invention is manufactured by granulating the binder composition of this invention, a positive electrode active material, and the electrically conductive agent used as needed.

The method of assembling the composite particles is not particularly limited and may be selected from the group consisting of spray drying and granulation, electroless layer assembly, compression assembly, agitation assembly, extrusion assembly, crushing assembly, fluidized bed assembly, fluidized bed multifunctional assembly, , And the like. Especially, since the composite particle which the binder composition and the electrically conductive agent are unevenly distributed in the surface vicinity is obtained easily, the spray drying granulation method is preferable. Using composite particles obtained by spray drying granulation method. The secondary battery positive electrode of this invention can be obtained with high productivity. In addition, the internal resistance of the secondary battery positive electrode can be further reduced.

In the spray drying granulation method, the slurry composition for secondary battery positive electrodes of this invention is spray-dried and granulated, and a composite particle is obtained. Spray drying is performed by spraying and drying a slurry composition in hot air. An atomizer is mentioned as an apparatus used for spraying a slurry composition. Atomizer has two types of devices, a rotary disc type and a pressure type. The rotating disk method introduces a slurry composition into the center of a disk which rotates at high speed, and the slurry composition is sent out of the disk by the centrifugal force of the disk, and the slurry composition is made into a fog at that time. The rotational speed of the disk depends on the size of the disk, but is usually 5,000 to 40,000 rpm, preferably 15,000 to 40,000 rpm. The lower the rotational speed of the disk, the larger the spray droplet, and the larger the weight average particle diameter of the resulting composite particles. As the rotator disk type atomizer, there can be mentioned a pin type and a vane type, but it is preferably a pin type atomizer. Fin-type atomizer is a kind of centrifugal spraying apparatus using a spraying pan, and is equipped with a plurality of spraying rollers so that the spraying pan is freely detached on a substantially concentric circle along the circumferential edge between the upper and lower disks. have. The slurry composition is introduced from the spray pan center and attached to the spray roller by centrifugal force to move the roller surface outward and finally spray away from the roller surface. On the other hand, a pressurization system is a system which pressurizes a slurry composition and makes a mist form from a nozzle, and makes it dry.

The temperature of the slurry composition to be sprayed is usually room temperature, but may be heated to room temperature or higher. The temperature of the hot air at spray drying is usually 80 to 250 ° C, preferably 100 to 200 ° C.

In spray drying, the method of spraying hot air is not particularly limited, and for example, a method in which hot air and a spraying direction co-flow in a transverse direction, a method sprayed at the top of a drying tower and descending with hot air, and sprayed And a method in which the water droplets and the hot air are in countercurrent contact, and the sprayed water droplets co-current with the initial hot air and then drop by gravity to countercurrently contact.

It is preferable that the shape of the composite grain | particle used preferably for this invention is substantially spherical. That is, the uniaxial diameter of the composite particles is L _s , the major axis diameter diameter is L _l , L _a = (L _s + L _l ) / 2, and the value of (1- (L _l -L _s ) / L _a ) × 100 When making it the sphericity (%), it is preferable that sphericity is 80% or more, More preferably, it is 90% or more. Here, the short axis diameter L _s and the long axis diameter diameter L _l are values measured from the transmission electron microscope photographic image.

The volume average particle diameter of the composite grain | particle used preferably for this invention is 10-100 micrometers normally, Preferably it is 20-80 micrometers, More preferably, it is the range of 30-60 micrometers. The volume average particle diameter can be measured using a laser diffraction particle size distribution measuring device.

In the present invention, the feeder used in the step of supplying the composite particles on the current collector is not particularly limited, but is preferably a quantitative feeder capable of supplying the composite particles quantitatively. Here, the quantitative supply is a CV value obtained by continuously supplying the composite particles using such a feeder, measuring the supply amount a plurality of times at regular intervals, and obtaining the mean value (m) and the standard deviation (σm) of the measured values. It says that (= (sigma) m / m * 100) is four or less. The quantitative feeder preferably used in the present invention has a CV value of preferably 2 or less. Specific examples of the metering feeder include a gravity feeder such as a table feeder and a rotary feeder, a mechanical feeder such as a screw feeder and a belt feeder, and the like. Among them, a rotary feeder is preferable.

Next, the current collector and the supplied composite particles are pressed with a pair of rolls to form a positive electrode active material layer on the current collector. In this process, the said composite particle heated as needed is shape | molded to a sheet-like positive electrode active material layer with a pair of rolls. The temperature of the supplied composite particles is preferably 40 to 160 캜, more preferably 70 to 140 캜. When the composite particles in this temperature range are used, the composite particles are not slipped on the surface of the press roll, and the composite particles are continuously and uniformly supplied to the press roll, so that the film thickness is uniform and the electrode density is small. And a positive electrode active material layer can be obtained.

The temperature at the time of shaping | molding is 0-200 degreeC normally, and it is preferable that it is higher than melting | fusing point or glass transition temperature of the binder used for this invention, and it is more preferable that it is 20 degreeC or more at melting | fusing point or glass transition temperature. The forming speed in the case of using a roll is usually more than 0.1 m / min, preferably 35 to 70 m / min. The press line pressure between press rolls is usually 0.2 to 30 kN / cm, preferably 0.5 to 10 kN / cm.

In the said manufacturing method, although the arrangement | positioning of said pair of roll is not specifically limited, It is preferable to arrange | position substantially horizontally or almost vertically. In the case of being disposed almost horizontally, the current collector is continuously supplied between a pair of rolls, and the composite particles are supplied to at least one of the rolls so that the composite particles are supplied to the gap between the current collector and the roll, and the positive electrode active material is pressed. A layer can be formed. In the case of arranging it almost vertically, the current collector is conveyed in the horizontal direction, the composite particles are fed onto the current collector, and the supplied composite particles are leveled with a blade or the like as necessary, and then the current collector is a pair of rolls. The positive electrode active material layer can be formed by supplying to the liver.

In manufacturing the secondary battery positive electrode of this invention, after forming the positive electrode active material layer which consists of said slurry composition on an electrical power collector, the porosity of a positive electrode active material layer is made low by pressurization process using a metal mold | die press, a roll press, etc. It is desirable to have a process. The range with preferable porosity is 5 to 30%, More preferably, it is 7 to 20%. If the porosity is too high, the charging efficiency and the discharge efficiency are deteriorated. If the porosity is too low, a high volume capacity is hardly obtained, causing a problem that the positive electrode active material layer peels well from the current collector and easily causes defects. Moreover, when using a curable polymer for a binder composition, it is preferable to harden | cure.

The thickness of the positive electrode active material layer in the secondary battery positive electrode of this invention is 5-300 micrometers normally, Preferably it is 10-250 micrometers. When the thickness of the positive electrode active material layer is in the above range, both the load characteristics and the cycle characteristics exhibit high characteristics.

In this invention, the content rate of the positive electrode active material in a positive electrode active material layer becomes like this. Preferably it is 90-99.9 mass%, More preferably, it is 95-99 mass%. By making the content rate of a positive electrode active material into the said range, flexibility and binding property can be exhibited, showing a high capacity | capacitance.

(Whole house)

The current collector used in the present invention is not particularly limited as long as it is an electrically conductive material and is an electrochemically durable material. However, the current collector is preferably a metal material because of its heat resistance. For example, iron, copper, aluminum, nickel, Stainless steel, titanium, tantalum, gold, platinum and the like. Especially, aluminum is especially preferable as an electrical power collector used for a secondary battery positive electrode. Although the shape of an electrical power collector is not specifically limited, It is preferable that it is a sheet form with a thickness of about 0.001-0.5 mm. In order that an electrical power collector may raise adhesive strength with a positive electrode active material layer, it is preferable to use it, roughening previously. Examples of the roughening method include mechanical roughening, electrolytic roughening, and chemical roughening. In the mechanical polishing method, a polishing cloth on which abrasive particles are fixed, a wire brush provided with a grindstone, an emery buff, a steel wire, or the like is used. Moreover, in order to improve the adhesive strength and electroconductivity of a mixture, you may form an intermediate | middle layer in the electrical power collector surface, and especially, it is preferable to form a conductive adhesive layer.

(4) secondary battery

The secondary battery of this invention is a secondary battery provided with a positive electrode, a negative electrode, a separator, and electrolyte solution, A positive electrode is the said secondary battery positive electrode.

(Negative electrode)

The negative electrode is formed by stacking a negative electrode active material layer containing a negative electrode active material and a binder composition for a secondary battery negative electrode on a current collector.

(Negative electrode active material)

The negative electrode active material used for this invention is a substance which exchanges electrons in a secondary battery negative electrode.

Specific examples of the negative electrode active material for a lithium ion secondary battery include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), and pitch-based carbon fibers; conductive polymers such as polyacene, and the like. Can be. Preferably, it is a crystalline carbonaceous material such as graphite, natural graphite, mesocarbon microbeads (MCMB). Moreover, as a negative electrode active material, metals, such as silicon, tin, zinc, manganese, iron, nickel, these alloys, the oxide or sulfate of the said metal or alloy can be used. In addition, lithium alloys such as metallic lithium, Li-Al, Li-Bi-Cd, Li-Sn-Cd, lithium transition metal nitrides, silicon and the like can also be used. The said negative electrode active material can be used individually or in combination of 2 or more types.

The shape of the negative electrode active material is preferably grained. If the particle shape is spherical, an electrode having a higher density than that at the time of electrode molding can be formed.

Although the volume average particle diameter of a negative electrode active material is suitably selected by the combination with the other structural requirements of a battery, Usually, it is 0.1-100 micrometers, Preferably it is 1-50 micrometers, More preferably, it is 5-20 micrometers. The 50% volume cumulative diameter of the negative electrode active material is usually 1 to 50 µm, preferably 15 to 30 µm, from the viewpoint of improvement of battery characteristics such as initial efficiency, load characteristics, and cycle characteristics.

Although the tap density of a negative electrode active material is not specifically limited, What is 0.6 g / cm <3> or more is used preferably.

The content rate of the negative electrode active material in a negative electrode active material layer becomes like this. Preferably it is 85-99 mass%, More preferably, it is 88-97 mass%. By making the content rate of a negative electrode active material into the said range, flexibility and binding property can be exhibited, showing a high capacity | capacitance.

In the present invention, the density of the negative electrode active material layer of the secondary battery negative electrode is preferably 1.6 to 1.9 g / cm 3, and more preferably 1.65 to 1.85 g / cm 3. When the density of the negative electrode active material layer is in the above range, a high capacity battery can be obtained.

(Binder composition for secondary battery negative electrode)

The binder composition for secondary battery negative electrodes is not particularly limited and known ones can be used. For example, polyethylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyacrylic acid derivatives, polyacrylonitrile derivatives, and the like. In addition, soft polymers such as an acrylic soft polymer, a diene soft polymer, an olefin soft polymer, and a vinyl soft polymer can be used. These may be used independently and may use 2 or more types together.

In addition to the above components, the negative electrode may further contain other components such as the above-described conductive agent, thickener, reinforcing material, leveling agent and electrolyte additive having a function of suppressing decomposition of electrolyte solution. They are not particularly limited as long as they do not affect the cell reaction.

The current collector may be a current collector used for the secondary battery positive electrode described above, and is not particularly limited as long as it is an electrically conductive and electrochemically durable material. Copper is particularly preferable for the secondary battery negative electrode.

The thickness of a negative electrode active material layer is 5-300 micrometers normally, Preferably it is 10-250 micrometers. When the thickness of the negative electrode active material layer is in the above range, both the load characteristics and the energy density exhibit high characteristics.

A negative electrode can be manufactured similarly to the secondary battery positive electrode mentioned above.

(Separator)

The separator is a porous substrate having pores, and the usable separators include (a) a porous separator having pores, (b) a porous separator having a polymer coat layer formed on one or both surfaces thereof, or (c) an inorganic ceramic powder. The porous separator in which the porous resin coat layer was formed is mentioned. Non-limiting examples thereof include polypropylene, polyethylene, polyolefin, or aramid porous separator, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile or polyvinylidene fluoride hexafluoropropylene copolymer, and the like. Polymer films for solid polymer electrolytes or gel polymer electrolytes, separators coated with a gelled polymer coat layer, or separators coated with a porous membrane layer made of an inorganic filler and a dispersant for an inorganic filler.

(Electrolytic solution)

Although the electrolyte solution used for this invention is not specifically limited, For example, what melt | dissolved lithium salt in the non-aqueous solvent as a supporting electrolyte can be used. Lithium salts include, for _{example, LiPF 6, LiAsF 6, LiBF} 4, LiSbF 6, LiAlCl 4, LiClO 4, CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) ₂ NLi, (CF ₃ SO ₂ ) ₂ NLi, and (C ₂ F ₅ SO ₂ ) NLi. In particular, LiPF ₆ , LiClO ₄ , CF ₃ SO ₃ Li, which dissolves well in a solvent and exhibits high dissociation, is preferably used. These can be used individually or in mixture of 2 or more types. The amount of the supporting electrolyte is usually 1% by mass or more, preferably 5% by mass or more, and usually 30% by mass or less, preferably 20% by mass or less with respect to the electrolyte solution. Even if the amount of the supporting electrolyte is excessively at least too large, the ionic conductivity is lowered and the charging and discharging characteristics of the battery are lowered.

The solvent used for the electrolytic solution is not particularly limited as long as it dissolves the supporting electrolyte, but is usually dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate ( BC) and alkyl carbonates such as methyl ethyl carbonate (MEC); esters such as γ-butyrolactone and methyl formate, ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfolane, and Sulfur-containing compounds, such as dimethyl sulfoxide, are used. Particularly, dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate and methyl ethyl carbonate are preferable because they are easy to obtain high ionic conductivity and have a wide temperature range for use. These can be used individually or in mixture of 2 or more types. Moreover, you may use it, containing an additive in electrolyte solution. As an additive, carbonate type compounds, such as vinylene carbonate (VC), are preferable.

In other than the electrolytic solution, there may be mentioned an inorganic solid electrolyte of polyethylene oxide, a gel polymer electrolyte or by impregnating an electrolytic solution in the polymer electrolyte, such as polyacrylonitrile, lithium sulfide, such as LiI, Li ₃ N.

(Method for Manufacturing Secondary Battery)

The manufacturing method of the secondary battery of this invention is not specifically limited. For example, the above-mentioned negative electrode and the positive electrode are superimposed via a separator, wound, or bent along the shape of the battery, placed in a battery container, and the electrolyte is injected into the battery container and sealed. If necessary, an expanded metal, an overcurrent preventing element such as a fuse, a PTC element, a lead plate, or the like may be placed to prevent pressure increase and overcharge / discharge inside the battery. The shape of the battery may be any of a laminate cell type, a coin type, a button type, a sheet type, a cylindrical shape, a square shape, and a flat type.

Example

Although an Example is given to the following and this invention is demonstrated, this invention is not limited to this. In addition, the part and% in a present Example are a mass reference | standard unless there is particular notice. In Examples and Comparative Examples, various physical properties were evaluated as follows.

<Storage stability of the binder composition>

To 100 g of binder composition, 5 g of a binder composition (mixed bacteria number 10 ⁶ or more: unit cfu / ml, abbreviation of cfu = Colony Forming Unit, unit of viable cell number) was observed, and added separately at 30 ° C. It was left to stand for 12 hours, and after maintaining heat retention at 50 degreeC for 7 days again, it returned to 30 degreeC and stored for 24 hours. Thereafter, the number of colonies after incubation at 30 ° C. for 48 hours is visually counted using a TGC (thiograte acid) salt agar plate mixing method. The above was made into the 1st inoculation test.

In the second test, 5 g of the above-mentioned decay binder composition was further added, stored and managed under the same temperature conditions as above, and the number of colonies was counted in the same manner as described above. These operations were repeated inoculation and measurement of the corrupt binder composition until colonies were confirmed (finished at 10 ⁶ or more).

And long term storage stability was determined as follows according to the said inoculation frequency until colony was confirmed. The larger the number of inoculations, the higher the long-term storage stability of the binder composition.

A: The number of inoculations until colony is confirmed more than six times

B: The number of inoculations until colony is confirmed is more than three times five times or less

C: The number of inoculations until colony is confirmed is less than two times

<Peel Strength>

The positive electrode in which the electrode active material layer was formed was cut into the square of 2.5 cm in width x 10 cm in length, and it was set as the test piece, and the electrode active material layer surface was fixed up. After affixing a cellophane tape on the surface of the electrode active material layer of a test piece, the stress at the time of peeling a cellophane tape in 180 degree direction at the speed of 50 mm / min from one end of a test piece was measured. The measurement is performed 10 times, the average value is obtained, and this is set as the peel strength (N / m), and this is evaluated based on the following criteria using the evaluation criteria of the peel strength. The larger the value, the better the adhesion between the electrode active material layer and the current collector.

A ： 15 N / m or more

B: 10 N / m or more-less than 15 N / m

C: 5.0 N / m or more-less than 10 N / m

D ： Less than 5.0 N / m

<Charge / Discharge Cycle Characteristics (60 ° C)>

The 10-cell full cell coin-type battery was charged to 4.3 V by a 0.2 C constant current method under a 60 ° C. atmosphere, and the charge and discharge discharged to 3.0 V were repeated to measure the electric capacity. The average value of 10 cells was used as the measured value, and the charge / discharge capacity retention rate expressed by the ratio (%) of the capacitance at the end of 50 cycles and the capacitance at the end of 5 cycles was obtained. do. The higher this value, the better the high temperature cycle characteristics.

A: 80% or more

B: 70% or more and less than 80%

C: 50% or more and less than 70%

D ： 30% or more and less than 50%

E ： less than 30%

(Example 1)

(Preparation of binder composition)

70 parts of ion-exchange water and 0.3 part of sodium dodecylbenzenesulfonate were respectively supplied to the reactor provided with the stirrer, and it stirred and mixed sufficiently, substituted the gaseous-phase part with nitrogen gas, and heated up at 70 degreeC. On the other hand, 50 parts of ion-exchanged water, 0.5 parts of sodium dodecylbenzenesulfonate, and 78 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile, 1.8 parts of methacrylic acid, allyl methacrylate as another container 0.2 parts were mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours to effect polymerization. The reaction was started by adding 0.5 parts of potassium persulfate as an aqueous 3% potassium persulfate solution to the reactor at the start of the addition of the monomer mixture, and reacting at 60 ° C during the addition of the monomer mixture. After completion of the addition, the mixture was further stirred at 80 ° C for 3 hours to terminate the reaction, thereby obtaining an aqueous dispersion (binder dispersion) containing a binder. The polymerization conversion rate was 98.5%.

(Addition of isothiazoline compound and chelate compound)

After cooling the obtained binder dispersion liquid at 25 degreeC, the sodium hydroxide aqueous solution was added 5%, pH was adjusted to 8, and the unreacted monomer was removed by heat-pressure distillation. And it cooled until it became 30 degrees C or less, and fine-adjusted so that it might become pH 8 with 5% sodium hydroxide aqueous solution. Immediately thereafter, with respect to 100 parts of the solid content of the binder, 0.05 parts of BIT, 0.25 parts of EDTA, and 0.02 parts of sodium pyrithione were added and mixed, and further subjected to the adjustment of the solid content concentration with ion-exchanged water. It filtered by the stainless steel wire mesh of 77 micrometers), and obtained the binder composition of 40% of solid content concentration. The storage stability of the binder composition was evaluated using the prepared binder composition. The results are shown in Table 1.

(Manufacture of the slurry composition for secondary battery positive electrodes)

100 parts of spinel manganese (LiMn ₂ O ₄ ; Mn content 60%), acetylene black (HS-100: Denki Chemical Industries), 2.5 parts of solid binder concentration (40% solids), and an etherification degree as a thickener as an electrode active material 40 parts of carboxymethylcellulose aqueous solution of which 0.8 is (2% of solid content concentration), and an appropriate amount of water were stirred with the planetary mixer, and the slurry composition for positive electrodes was prepared.

(Manufacture of secondary battery positive electrode)

The slurry composition for the positive electrode was applied on a 20 μm thick aluminum foil with a comma coater so that the film thickness after drying was about 70 μm, dried at 60 ° C. for 20 minutes, and then heated at 150 ° C. for 2 hours to obtain an electrode disc. . This electrode disk was rolled by the roll press, and the positive electrode plate (secondary battery positive electrode) by which density was controlled to 65 micrometers which consists of 2.1 g / cm <3>, aluminum foil, and an electrode active material layer was produced. Peel strength measurement was performed using the produced electrode plate. The results are shown in Table 1.

(Production of battery)

The positive electrode plate is cut out into a disk shape having a diameter of 16 mm, and a separator comprising a porous film made of a disk-shaped polypropylene having a diameter of 18 mm and a thickness of 25 µm on the active material layer side of the positive electrode, metal lithium used as a negative electrode, expanded metal The laminates were sequentially stacked and housed in a stainless steel coin-type outer container (diameter 20 mm, height 1.8 mm, stainless steel thickness 0.25 mm) provided with a polypropylene packing. The electrolyte is injected into the container so that no air remains, and the outer container is fixed with a 0.2 mm thick stainless steel cap through a polypropylene packing, and the battery can is sealed, and a lithium can having a diameter of 20 mm and a thickness of about 2 mm. An ion coin battery was prepared.

In the electrolyte, LiPF ₆ was dissolved at a concentration of 1 mol / liter in a mixed solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) in EC: DEC = 1: 2 (volume ratio at 20 ° C). Solution was used.

Charge / discharge cycle characteristics (60 ° C) were evaluated using this battery.

The results are shown in Table 1.

(Example 2)

(Preparation of binder composition)

70 parts of ion-exchange water, 0.2 part of sodium dodecylbenzenesulfonate, and 0.25 part of EDTA were supplied to the reactor provided with the stirrer, and the gaseous-phase part was substituted with nitrogen gas, and it heated up at 70 degreeC. On the other hand, 50 parts of ion-exchanged water, 0.5 parts of sodium dodecylbenzenesulfonate, and 78 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile, 1.8 parts of methacrylic acid, allyl methacrylate as another container 0.2 parts were mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours to effect polymerization. The reaction was started by adding 0.5 parts of potassium persulfate as an aqueous 3% potassium persulfate solution to the reactor at the start of addition of the monomer mixture, and reacting at 60 ° C during the monomer mixture addition. After completion of the addition, the mixture was further stirred at 80 ° C for 3 hours to terminate the reaction, thereby obtaining an aqueous dispersion (binder dispersion) containing a binder. The polymerization conversion rate was 98.6%.

(Addition of isothiazoline compound)

After cooling the obtained binder dispersion liquid at 25 degreeC, after adding a 5% sodium hydroxide aqueous solution and adjusting pH to 8, the unreacted monomer was removed by heat-reduced-pressure distillation. And it cooled to 30 degrees C or less, and fine-adjusted so that it might become pH 8 with 5% sodium hydroxide aqueous solution. Immediately thereafter, 0.05 parts of BIT and 0.02 parts of sodium pyrithione were added and mixed with respect to 100 parts of the solid content of the binder, and the solid content concentration was further adjusted with ion-exchanged water. Filtration was performed with the stainless steel wire mesh, and the binder composition of 40% of solid content concentration was obtained.

Except having used the said binder composition, operation similar to Example 1 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 1.

(Example 3)

Except having used MIT instead of BIT, operation similar to Example 1 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced, and the evaluation was performed. The results are shown in Table 1.

(Example 4)

The same operation as in Example 1 was carried out except that the amount of EDTA was added to 0.015 parts by using CIT instead of BIT, and sodium pyrithione was not added, to obtain a binder composition, to prepare a slurry composition, a positive electrode and a battery, Evaluation was performed. The results are shown in Table 1.

(Example 5)

The same operation as in Example 1 was carried out except that the amount of EDTA was added to 0.3 part by using OIT instead of BIT, and sodium pyrithione was not added, to obtain a binder composition, to prepare a slurry composition, a positive electrode and a battery, Evaluation was performed. The results are shown in Table 1.

(Example 6)

The same operation as in Example 1 was carried out except that MIT 0.025 parts and CIT 0.025 parts were used, and the amount of EDTA added was 0.005 parts, and sodium pyrithione was not added, thereby obtaining a binder composition, a slurry composition, a positive electrode and The battery was produced and evaluated. The results are shown in Table 1.

(Example 7)

(Preparation of binder composition)

75 parts of ion-exchanged water and 0.3 parts of sodium dodecylbenzenesulfonate were respectively supplied to the reactor provided with the stirrer, the gaseous-phase part was substituted with nitrogen gas, and it heated up at 70 degreeC. On the other hand, 50 parts of ion-exchanged water, 0.5 parts of sodium dodecylbenzenesulfonate, and 78 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile, 1.8 parts of methacrylic acid, glycidyl meta to another container 0.2 part of acrylate was mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours to effect polymerization. The reaction was started by adding 0.5 parts of potassium persulfate as an aqueous 3% potassium persulfate solution to the reactor at the start of addition of the monomer mixture, and reacting at 60 ° C during the monomer mixture addition. After completion of the addition, the mixture was further stirred at 80 ° C for 3 hours to terminate the reaction, thereby obtaining an aqueous dispersion (binder dispersion) containing a binder. The polymerization conversion rate was 97.5%.

(Addition of isothiazoline compound and chelate compound)

After cooling the obtained binder dispersion liquid at 25 degreeC, after adding a 5% sodium hydroxide aqueous solution and adjusting pH to 8, the unreacted monomer was removed by heat-reduced-pressure distillation. And it cooled to 30 degrees C or less, and fine-adjusted so that it might become pH 8 with 5% sodium hydroxide aqueous solution. Immediately thereafter, with respect to 100 parts of the solid content of the binder, 0.05 parts of BIT, 0.25 parts of EDTA, and 0.02 parts of sodium pyrithione were added and mixed, and further subjected to the adjustment of the solid content concentration with ion-exchanged water. It filtered by the stainless steel wire mesh of 77 micrometers), and obtained the binder composition of 40% of solid content concentration.

Except having used the said binder composition, operation similar to Example 1 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 1.

(Example 8)

(Preparation of binder composition)

75 parts of ion-exchanged water, 0.2 parts of sodium dodecylbenzenesulfonate, and 2 parts of itaconic acid were supplied as a polymerizable monomer to the reactor equipped with the stirrer, and it stirred and mixed sufficiently, the gaseous-phase part was replaced with nitrogen gas, and it heated up at 80 degreeC. . On the other hand, 60 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate, and 76 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile, and 2 parts of itaconic acid were mixed in another container to obtain a monomer mixture. . This monomer mixture was continuously added to the reactor over 4 hours to effect polymerization. The reaction was started by adding 0.5 parts of potassium persulfate as an aqueous 3% potassium persulfate solution to the reactor at the start of the addition of the monomer mixture, and during the monomer mixture addition, the reaction was carried out at 80 ° C. After completion of the addition, the mixture was further stirred at 90 ° C for 3 hours to terminate the reaction, thereby obtaining an aqueous dispersion (binder dispersion) containing a binder. The polymerization conversion rate was 96.0%.

(Addition of isothiazoline compound and chelate compound)

After cooling the obtained binder dispersion liquid at 25 degreeC, after adding a 5% sodium hydroxide aqueous solution and adjusting pH to 8, the unreacted monomer was removed by heat-reduced-pressure distillation. And it cooled to 30 degrees C or less, and fine-adjusted so that it might become pH 8 with 5% sodium hydroxide aqueous solution. Immediately thereafter, with respect to 100 parts of the solid content of the binder, 0.05 parts of BIT, 0.05 parts of EDTA, and 0.02 parts of sodium pyrithione were added and mixed, and further subjected to solid content concentration adjustment with ion-exchanged water. It filtered by the stainless steel wire mesh of 77 micrometers), and obtained the binder composition of 40% of solid content concentration.

Except having used the said binder composition, operation similar to Example 1 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 1.

(Example 9)

Except having used CIT instead of BIT and NTA instead of EDTA, operation similar to Example 8 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced and evaluated. The results are shown in Table 1.

(Example 10)

The same operation as in Example 8 was carried out except that the amount of BIT added was 0.3 parts, CyDTA was used instead of EDTA, and sodium pyrithione was not added, thereby obtaining a binder composition to prepare a slurry composition, a positive electrode and a battery. , Evaluation was conducted. The results are shown in Table 1.

(Example 11)

Except having used OIT instead of BIT and DTPA instead of EDTA, operation similar to Example 8 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced and evaluated. The results are shown in Table 1.

(Example 12)

Except having used OIT instead of BIT and EGTA instead of EDTA, operation similar to Example 8 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced and evaluated. The results are shown in Table 1.

(Example 13)

Except having used HEDTA instead of EDTA, operation similar to Example 8 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced, and the evaluation was performed. The results are shown in Table 1.

(Example 14)

Except having used DHEG instead of EDTA, operation similar to Example 8 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced and evaluated. The results are shown in Table 1.

(Example 15)

(Preparation of binder composition)

75 parts of ion-exchanged water, 0.2 parts of sodium dodecylbenzenesulfonate, and 2 parts of itaconic acid were supplied as a polymerizable monomer to the reactor equipped with the stirrer, and it stirred and mixed sufficiently, the gaseous-phase part was replaced with nitrogen gas, and it heated up at 80 degreeC. . On the other hand, in another container, 60 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate, and 80 parts of 2-ethylhexyl acrylate, 16 parts of methacrylonitrile, 1 part of itaconic acid, 0.9 part of acrylic acid, as polymerizable monomers, 0.1 part of ethylene dimethacrylate was mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours to effect polymerization. The reaction was started by adding 0.5 parts of potassium persulfate as an aqueous 3% potassium persulfate solution to the reactor at the start of addition of the monomer mixture, and reacting at 80 ° C during the monomer mixture addition. After completion of the addition, the mixture was further stirred at 90 ° C for 3 hours to terminate the reaction, thereby obtaining an aqueous dispersion (binder dispersion) containing a binder. The polymerization conversion rate was 97.5%.

(Addition of isothiazoline compound and chelate compound)

After cooling the obtained binder dispersion liquid at 25 degreeC, after adding a 5% sodium hydroxide aqueous solution and adjusting pH to 8, the unreacted monomer was removed by heat and pressure distillation. And it cooled to 30 degrees C or less, and fine-adjusted so that it might become pH 8 with 5% sodium hydroxide aqueous solution. Immediately thereafter, 200 parts of mesh (scale interval approx.) Were added and mixed with 0.05 parts of BIT, 0.05 parts of HEDP, and 0.02 parts of sodium pyrithione to 100 parts of the solid content of the binder, and further subjected to solid concentration adjustment with ion-exchanged water. It filtered by the stainless steel wire mesh of 77 micrometers), and obtained the binder composition of 40% of solid content concentration.

Except having used the said binder composition, operation similar to Example 8 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 1.

(Example 16)

(Preparation of binder composition)

To the reactor equipped with a stirrer, 70 parts of ion-exchanged water, 0.2 part of sodium dodecylbenzenesulfonate, and 1 part of fumaric acid were supplied as a polymerizable monomer, and the mixture was sufficiently stirred and mixed, the gaseous phase was replaced with nitrogen gas, and heated to 80 ° C. On the other hand, in another container, 60 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate, and 76 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile, 1 part of fumaric acid, 1 part of methacrylic acid, as polymerizable monomers, 1 part of acrylic acid was mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours to effect polymerization. The reaction was started by adding 0.5 parts of potassium persulfate as an aqueous 3% potassium persulfate solution to the reactor at the start of addition of the monomer mixture, and reacting at 60 ° C during the monomer mixture addition. After completion of the addition, the mixture was further stirred at 70 ° C. for 3 hours to terminate the reaction, thereby obtaining an aqueous dispersion (binder dispersion) containing a binder. The polymerization conversion rate was 96.8%.

(Addition of isothiazoline compound and chelate compound)

After cooling the obtained binder dispersion liquid at 25 degreeC, after adding a 5% sodium hydroxide aqueous solution and adjusting pH to 8, the unreacted monomer was removed by heat-reduced-pressure distillation. And it cooled to 30 degrees C or less, and fine-adjusted so that it might become pH 8 with 5% sodium hydroxide aqueous solution. Immediately thereafter, 200 mesh (scale interval approx.) Was added to 100 parts of solids of the binder, 0.05 parts of BIT, 0.1 parts of citric acid, and 0.02 parts of sodium pyrithione were added and mixed, and further solids concentration adjustment was performed with ion-exchanged water. It filtered by the stainless steel wire mesh of 77 micrometers), and obtained the binder composition of 40% of solid content concentration.

Except having used the said binder composition, operation similar to Example 8 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 1.

(Example 17)

Except having used malic acid instead of citric acid, operation similar to Example 16 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced, and the evaluation was performed. The results are shown in Table 1.

(Example 18)

Except having used gluconic acid instead of citric acid, operation similar to Example 16 was performed, the binder composition was obtained, the slurry composition, the positive electrode, and the battery were produced, and the evaluation was performed. The results are shown in Table 1.

(Example 19)

(Preparation of binder composition)

To the reactor equipped with a stirrer, 70 parts of ion-exchanged water, 0.2 part of sodium dodecylbenzenesulfonate, and 1 part of itaconic acid were supplied as a polymerizable monomer, and the mixture was sufficiently stirred and mixed, the gaseous phase was replaced with nitrogen gas, and heated to 80 ° C. . On the other hand, in another vessel, 60 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate, and 77 parts of nonylacrylate as the polymerizable monomer, 20 parts of acrylonitrile, 1 part of itaconic acid, 0.5 part of acrylic acid, glycidyl methacryl 0.5 parts of rate were mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours to effect polymerization. The reaction was started by adding 0.5 parts of potassium persulfate as an aqueous 3% potassium persulfate solution to the reactor at the start of addition of the monomer mixture, and reacting at 80 ° C during the monomer mixture addition. After completion of the addition, the mixture was further stirred at 90 ° C for 3 hours to terminate the reaction, thereby obtaining an aqueous dispersion (binder dispersion) containing a binder. The polymerization conversion rate was 96.4%.

(Addition of isothiazoline compound and chelate compound)

After cooling the obtained binder dispersion liquid at 25 degreeC, after adding a 5% sodium hydroxide aqueous solution and adjusting pH to 8, the unreacted monomer was removed by heat-reduced-pressure distillation. And it cooled to 30 degrees C or less, and fine-adjusted so that it might become pH 8 with 5% sodium hydroxide aqueous solution. Immediately thereafter, 200 parts of mesh (scale interval approx.) Were added and mixed with 0.05 parts of BIT, 0.25 parts of EDTA, and 0.8 parts of sodium pyrithione to 100 parts of the solid content of the binder, and further subjected to solid concentration adjustment with ion-exchanged water. It filtered by the stainless steel wire mesh of 77 micrometers), and obtained the binder composition of 40% of solid content concentration.

Except having used the said binder composition, operation similar to Example 8 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 1.

(Comparative Example 1)

The addition amount of EDTA was 1.2 parts, and the operation similar to Example 1 was performed except having not added sodium pyrithione, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 2.

(Comparative Example 2)

Except not having added BIT and sodium pyrithione, operation similar to Example 1 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 2.

(Comparative Example 3)

Except that sodium pyrithione was not added and the addition amount of BIT was 1.2 parts, operation similar to Example 1 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 2.

(Comparative Example 4)

Except having used triazine instead of BIT and NTA instead of EDTA, operation similar to Example 8 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 2.

(Comparative Example 5)

Except not having added EDTA and sodium pyrithione, operation similar to Example 8 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 2.

(Comparative Example 6)

Except having used OIT instead of BIT and 0.1 part of succinic acid instead of EDTA, operation similar to Example 8 was performed, the slurry composition was obtained, the positive electrode and the battery were manufactured, and the evaluation was performed. The results are shown in Table 2.

From the result of Table 1, 2, the following can be described.

0.001-1.0 mass part of isothiazoline type compounds with respect to the binder which has a (meth) acrylic acid ester monomeric unit, the vinyl monomeric unit which has an acidic group, and the (alpha), (beta)-unsaturated nitrile monomeric unit, and 100 mass parts of this binder, and chelate By using the aqueous binder composition for secondary battery positive electrodes containing 0.001-1.0 mass part of compounds, the positive electrode with favorable adhesive strength can be obtained, and the secondary battery with favorable safety and charging / discharging cycling characteristics can be obtained. Moreover, long-term storage stability of this binder composition becomes favorable.

On the other hand, when the compounding quantity of a chelate compound exceeds the said range (comparative example 1), and when it does not contain an isothiazoline type compound (comparative examples 2 and 4), the compounding quantity of an isothiazoline type compound contains the said range. When exceeding (comparative example 3) and not containing a chelating compound (comparative examples 5 and 6), at least any one of long-term storage stability of a binder composition, adhesive strength of an electrode, and charge / discharge cycle characteristics falls.

Claims (8)

A binder having a (meth) acrylic acid ester monomer unit, a vinyl monomer unit having an acidic group, and an α, β-unsaturated nitrile monomer unit,
The aqueous binder composition for secondary battery positive electrodes containing 0.001-1.0 mass part of isothiazoline-type compounds and 0.001-1.0 mass part of chelate compounds with respect to 100 mass parts of this binder. The method of claim 1,
The aqueous binder composition for secondary battery positive electrodes in which the said binder further contains the other monomeric unit copolymerizable with each said monomeric unit, and that other monomeric unit is a monomeric unit which has a crosslinkable group. 3. The method according to claim 1 or 2,
The aqueous binder composition for secondary battery positive electrodes whose vinyl monomeric unit which has the said acidic group is a vinyl monomeric unit which has a carboxylic acid group. The method according to any one of claims 1 to 3,
The aqueous binder composition for secondary battery positive electrodes, wherein the chelate compound is selected from the group consisting of an aminocarboxylic acid chelate compound, a phosphonic acid chelate compound, gluconic acid, citric acid, malic acid, and tartaric acid. The method according to any one of claims 1 to 4,
The aqueous binder composition for secondary battery positive electrodes containing 0.001-1.0 mass part of pyrithione compounds with respect to 100 mass parts of said binders. The slurry composition for secondary battery positive electrodes containing the aqueous binder composition for secondary battery positive electrodes and positive electrode active material in any one of Claims 1-5. The secondary battery positive electrode formed by forming the positive electrode active material layer which consists of a slurry composition for secondary battery positive electrodes of Claim 6 on an electrical power collector. A secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode is the secondary battery positive electrode according to claim 7.