KR102384939B1 - Liquid adhesive coating for coating collector - Google Patents

Abstract

An adhesive coating solution for a current collector coat containing a binder and water, wherein the amount of aggregate generated in the Marron-type mechanical stability test of the coating solution is less than 0.3 wt.% based on the amount of solid content, and the contact angle with respect to copper foil is less than 60° , the measurement result in the loop tack test is 0.5 N/25 mm or more.

Description

Adhesive coating solution for current collector coat {LIQUID ADHESIVE COATING FOR COATING COLLECTOR}

The present invention relates to an adhesive coating liquid for a current collector coat used in manufacturing an electrochemical element.

BACKGROUND ART Electrochemical devices such as lithium ion secondary batteries that are small, lightweight, have high energy density and can be repeatedly charged and discharged are rapidly increasing in demand by making use of their characteristics. BACKGROUND ART Lithium ion secondary batteries have a relatively large energy density, and thus are used in fields such as cellular phones, notebook personal computers, and electric vehicles.

In these electrochemical elements, further improvements, such as low resistance, high capacity, and improvement of mechanical properties and productivity, are demanded with the expansion and power generation of applications. In such a situation, a manufacturing method with higher productivity is demanded also for an electrochemical element electrode, and various improvements are being implemented with respect to the manufacturing method which can be molded at high speed, and the material for electrochemical element electrode suitable for the manufacturing method.

An electrochemical element electrode is what laminates|stacks on an electrical power collector the electrode active material layer formed by normally binding an electrode active material and the electrically conductive agent used as needed with a binder normally. As a method of forming such an electrode active material layer, in Patent Documents 1 and 2, a particulate electrode material is obtained by spray-drying a slurry containing an electrode active material, rubber particles, and a dispersion medium, and an electrode active material layer is prepared using the obtained electrode material. A method of forming is disclosed.

Japanese Patent Publication No. 4219705 Japanese Patent Laid-Open No. 2007-18874

By the way, in order to improve the adhesiveness of an electrode active material layer and a collector, forming intermediate|middle layers, such as an adhesive bond layer, between an electrode active material layer and a collector is also implemented. However, when the electrode active material layer is formed on a portion where the coating solution for forming the adhesive layer is not coated, as in the method disclosed in Patent Documents 1 and 2, the resistance of the battery increases and the capacity retention rate decreases. performance deteriorates.

In addition, in the technique described in Patent Document 1, when preparing the slurry, since a viscosity modifier is not used, the viscosity of the slurry is low, and the binder is localized on the surface in the particulate electrode material, so the obtained particulate electrode material is liquidity fell. Therefore, there was a problem in moldability, such as not being able to manufacture an electrode having a uniform film thickness.

Moreover, at the time of manufacture of an electrode, taking out the elongate electrical power collector wound up in roll shape, for example, and forming an electrode active material layer on the electrical power collector is performed. Therefore, although it is calculated|required to manufacture the electrode which formed the uniform electrode active material layer on the elongate electrical power collector, patent document 1 and 2 did not describe about long formability.

It is an object of the present invention to provide an adhesive coating solution for a current collector coating capable of producing an electrochemical element electrode having good performance even at the time of long molding.

MEANS TO SOLVE THE PROBLEM As a result of earnest examination, this inventor discovered that the said objective could be achieved by using the adhesive agent coating liquid for electrical power collector coats which has a predetermined|prescribed physical-property value, and came to complete this invention.

That is, according to the present invention,

(1) An adhesive coating solution for a current collector coat containing a binder and water, wherein the amount of agglomerates generated in the Marron-type mechanical stability test of the coating solution is less than 0.3 wt.% based on the solid content, and the contact angle with respect to the copper foil is 60 °, and the measurement result in the loop tack test is 0.5 N/25 mm or more, the adhesive coating solution for the current collector coat,

(2) The adhesive coating solution for current collector coating according to (1), wherein the binder is a particulate binder;

(3) The adhesive coating solution for current collector coating according to (2), wherein the particulate binder has a glass transition temperature of -40°C or more and 10°C or less;

(4) The adhesive coating solution for current collector coating according to any one of (1) to (3), which contains a surfactant and has a concentration of the surfactant of 0.1 wt.% or more and less than 3 wt.%;

(5) The adhesive coating liquid for current collector coating in any one of (1)-(4) containing a tackiness-imparting material is provided.

ADVANTAGE OF THE INVENTION According to the adhesive agent coating liquid for electrical power collector coating which concerns on this invention, the electrochemical element which has favorable performance can be manufactured.

Hereinafter, the adhesive coating liquid for current collector coats of this invention is demonstrated. The adhesive coating solution for current collector coat of the present invention is an adhesive coating solution for current collector coating containing a binder and water, and the amount of aggregate generated in the Marron-type mechanical stability test of the coating solution is 0.3 wt.% based on the solid content. less than, the contact angle with respect to the copper foil is less than 60°, and the measurement result in the loop tack test is 0.5 N/25 mm or more. In addition, "wt.%" has the same meaning as "weight%".

(Binder)

The binder used in the present invention is a component for adhering the electrode active material to each other and to the current collector or other components, and is usually in the state of a dispersion in which polymer particles having binding properties are dispersed in water (binder aqueous dispersion) , or in a state of a solution in which a polymer having binding properties is dissolved in water (binder solution).

Examples of the polymer used for the aqueous binder dispersion include a diene-based polymer, an acrylic polymer, a fluorine-based polymer, and a silicone-based polymer.

Among these, since it is excellent in the adhesiveness of an electrical power collector and an electrode active material layer, a diene type polymer or an acrylic polymer is preferable. In addition, the adhesive layer obtained by the adhesive coating liquid for current collector coat is required to have high oxidation-reduction stability because it is used in the positive electrode and the negative electrode, and an acrylic polymer is most preferable from the viewpoint of particularly high oxidation stability in the positive electrode.

(Diene-based polymer)

A diene-type polymer is a polymer containing the monomeric unit formed by superposing|polymerizing conjugated dienes, such as a butadiene and an isoprene. The ratio of the monomer unit formed by superposing|polymerizing the conjugated diene in a diene polymer is 40 weight% or more normally, Preferably it is 50 weight% or more, More preferably, it is 60 weight% or more. As a polymer, Homopolymers of conjugated dienes, such as polybutadiene and polyisoprene; and a copolymer of a monomer copolymerizable with a conjugated diene. Examples of the copolymerizable monomer include α,β-unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; styrene-based monomers such as styrene, chlorostyrene, vinyltoluene, t-butylstyrene, vinylbenzoic acid, methyl vinylbenzoate, vinylnaphthalene, chloromethylstyrene, hydroxymethylstyrene, α-methylstyrene, and divinylbenzene; olefins such as ethylene and propylene; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; Heterocyclic-containing vinyl compounds, such as N-vinylpyrrolidone, a vinylpyridine, and vinylimidazole, are mentioned.

(Acrylic polymer)

An acrylic polymer is a polymer containing the monomeric unit formed by superposing|polymerizing an acrylic acid ester and/or a methacrylic acid ester. The ratio of the monomer unit formed by superposing|polymerizing the acrylic acid ester and/or methacrylic acid ester in an acrylic polymer is 40 weight% or more normally, Preferably it is 50 weight% or more, More preferably, it is 60 weight% or more. As a polymer, the homopolymer of acrylic acid ester and/or methacrylic acid ester, and the copolymer of this and the monomer copolymerizable are mentioned. As said copolymerizable monomer, Unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, and a fumaric acid; Carboxylic acid esters which have 2 or more carbon-carbon double bonds, such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and a trimethylol propane triacrylate; styrene-based monomers such as styrene, chlorostyrene, vinyltoluene, t-butylstyrene, vinylbenzoic acid, methyl vinylbenzoate, vinylnaphthalene, chloromethylstyrene, hydroxymethylstyrene, α-methylstyrene, and divinylbenzene; amide-based monomers such as acrylamide, N-methylolacrylamide, and acrylamide-2-methylpropanesulfonic acid; α,β-unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; olefins such as ethylene and propylene; diene-based monomers such as butadiene and isoprene; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; Heterocyclic-containing vinyl compounds, such as N-vinylpyrrolidone, a vinylpyridine, and vinylimidazole, are mentioned.

Examples of the polymer used in the binder solution include hydroxyethyl cellulose (HEC), polyethylene glycol (PEG), polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), poly Oxyethylene polyoxypropylene block copolymer (PPP), polyacrylamide (PMMA), polyN-vinylformamide (PNVF), polyacrylic acid (PAA), sodium polyacrylate (PAA-Na), ammonium polyacrylate (PAA-) NH4), sodium polystyrenesulfonate (PSS-Na), sodium carboxymethylcellulose (CMC-Na), polyethyleneimine (PEI), and the like.

It is preferable that the binder used for this invention is what was obtained through the particulate-form metal removal process of removing the particulate-form metal contained in a binder aqueous dispersion or binder solution in a manufacturing process. When the content of the particulate metal component contained in the binder is 10 ppm or less, there is little fear of an increase in self-discharge due to an internal short circuit of the battery or dissolution/precipitation during charging, and the cycle characteristics and safety of the battery are improved.

The method of removing the particulate metal component from the aqueous binder dispersion or binder solution in the particulate metal removal step is not particularly limited, and for example, a method of removing by filtration with a filtration filter, a method of removing with a vibrating sieve method, the method of removing by centrifugation, the method of removing by magnetic force, etc. are mentioned. Especially, since the removal object is a metal component, the method of removing by magnetic force is preferable. The magnetic removal method is not particularly limited as long as it is a method capable of removing the metal component, but in consideration of productivity and removal efficiency, it is preferably carried out by arranging a magnetic filter in the binder production line.

Moreover, it is preferable that a binder has a cationic group or an anionic group.

A cationic group is group _in which a substituent has cationic chemical functionality, a substituent has _{a formula R1R2R3R4N+(A-), In formula, R<1 >} ^{is as} _{follows .}

R ₁ is of the formula -CH ₂ -CHOH-CH ₂ -, or -CH ₂ -CH ₂ -, R ₂ , R ₃ , R ₄ are each independently alkyl having 1 to 20 carbon atoms or It is selected from an arylalkyl group, and A ^- is a halide ion, a sulfate ion, a phosphate ion, or a tetrafluoroborate ion.

When manufacturing a binder, a cationic group can be made to contain in a binder by copolymerizing a cationic group containing ethylenically unsaturated monomer, and then carrying out a neutralization process or a quaternization process as needed. Examples of the cationic group-containing ethylenically unsaturated monomer include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dipropylaminoethyl (meth)acrylate, diisopropylaminoethyl (meth)acrylate , dibutylaminoethyl (meth)acrylate, diisobutylaminoethyl (meth)acrylate, dit-butylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, diethylaminopropyl (meth) Acrylamide, dipropylaminopropyl (meth)acrylamide, diisopropylaminopropyl (meth)acrylamide, dibutylaminopropyl (meth)acrylamide, diisobutylaminopropyl (meth)acrylamide, dit-butylamino (meth)acrylic acid esters or (meth)acrylamides having a dialkylamino group such as propyl (meth)acrylamide; styrenes having a dialkylamino group such as dimethylaminostyrene and dimethylaminomethylstyrene; vinylpyridines such as 4-vinylpyridine and 2-vinylpyridine; N-vinyl heterocyclic compounds, such as N-vinylimidazole; acid-neutralized product or quaternary ammonium salt of a monomer having an amino group, such as vinyl ethers such as aminoethyl vinyl ether and dimethylaminoethyl vinyl ether; Diallyl type quaternary ammonium salts, such as dimethyl diallyl ammonium chloride and diethyl diallyl ammonium chloride, etc. are mentioned.

In addition, the anionic group is a group in which the substituent has anionic chemical functionality, and examples of the anionic chemical functional group include carboxylate, sulfate, sulfonate, phosphate, phosphonate, or a mixture thereof. there is.

When manufacturing a binder, an anionic group can be contained in a binder by copolymerizing an anionic group containing ethylenically unsaturated monomer. It does not specifically limit as an anionic group containing ethylenically unsaturated monomer, For example, Ethylenically unsaturated monocarboxylic acid monomers, such as acrylic acid and methacrylic acid; Ethylenically unsaturated polyhydric carboxylic acid monomers, such as itaconic acid, a maleic acid, a fumaric acid, and a butene tricarboxylic acid; partial ester monomers of ethylenically unsaturated polyhydric carboxylic acids such as monobutyl fumarate, monobutyl maleate, and mono2-hydroxypropyl maleate; polyhydric carboxylic acid anhydrides such as maleic anhydride and citraconic anhydride; ethylenically unsaturated carboxylic acid monomers such as; a monomer having a sulfonic acid group such as styrenesulfonic acid, allyloxybenzenesulfonic acid, methallyloxybenzenesulfonic acid, vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, and 4-sulfonic acid butyl methacrylate; can be heard These monomers can be used individually or in combination of 2 or more type.

Content of the monomeric unit used in order to contain an anionic group or cationic group in the binder used for this invention becomes like this. Preferably it is 0.5-5 wt.%, More preferably, it is 1-4 wt.%. When there is too much content of the said monomeric unit, the resistance of the electrochemical element electrode obtained will become high. Moreover, when there is too little content of the said monomeric unit, the amount of aggregates in the adhesive coating liquid for electrical power collector coating obtained will increase.

Although the shape of the binder used for this invention is not specifically limited, It is preferable that it is particulate form. By being particulate, binding property is favorable, and the fall of the capacity|capacitance of the produced electrode, and deterioration by repetition of charging/discharging can be suppressed. As a particulate-form binder, the thing of the state in which the particle|grains of the binder like latex were disperse|distributed in water, and the powdery thing obtained by drying such a dispersion, for example are mentioned.

Moreover, the average particle diameter of the binder in a binder aqueous dispersion becomes like this. Preferably it is 50-500 nm, More preferably, it is 70-400 nm.

The glass transition temperature (Tg) of the binder is appropriately selected depending on the purpose of use, preferably -40°C or more and 10°C or less, more preferably -35°C or more and 10°C or less, still more preferably -30°C or more. It is in the range below 0 °C. When Tg of a binder is too high, the tackiness of the adhesive coating liquid for collector coatings obtained will lose|disappear. Moreover, when Tg of a binder is too low, the intensity|strength of the electrochemical element electrode obtained will fall.

The solid content concentration of the aqueous binder dispersion is preferably 15 to 70 wt.%, more preferably 20 to 65 wt.%, further from the viewpoint of good workability in the production of the current collector coating adhesive coating solution. Preferably it is 30-60 wt.%.

(Surfactants)

The adhesive coating liquid for current collector coating of this invention may contain surfactant. The surfactant is not particularly limited as long as it imparts wettability to the current collector of the adhesive coating liquid for current collector coating, but it is preferable to use a nonionic surfactant from the viewpoint of having little adverse effect on the electrochemical device to be obtained. . Nonionic surfactants include polyoxyalkylene alkylaryl ether surfactants, polyoxyalkylene alkyl ether surfactants, polyoxyalkylene fatty acid ester surfactants, sorbitan fatty acid ester surfactants, silicone surfactants, and acetylene alcohol surfactants. Surfactant, a fluorine-containing surfactant, etc. are mentioned.

Polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene dodecylphenyl ether are mentioned as polyoxyalkylene alkylaryl ether surfactant.

Polyoxyethylene oleyl ether and polyoxyethylene lauryl ether are mentioned as polyoxyalkylene alkyl ether surfactant.

As polyoxyalkylene fatty acid ester surfactant, polyoxyethylene oleic acid ester, polyoxyethylene lauric acid ester, and polyoxyethylene distearic acid ester are mentioned.

Examples of the sorbitan fatty acid ester surfactant include sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate. .

Dimethyl polysiloxane etc. are mentioned as a silicone type surfactant.

Examples of the acetylene alcohol-based surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl -1-hexyne-3ol and the like.

As a fluorine-containing surfactant, a fluorine alkyl ester etc. are mentioned.

The content of the surfactant in the adhesive coating liquid for a current collector coat of the present invention is 0.1 wt.% or more and less than 3 wt.%, Preferably 0.1 wt.% or more and less than 1 wt.%, More preferably, 0.2 wt. .% or more and less than 0.8 wt.%. When there is too much content of surfactant, the resistance of the lithium ion secondary battery obtained will rise. Moreover, when there is too little content of surfactant, the adhesive agent coating liquid for electrical power collector coating cannot be coated on an electrical power collector.

(Taxity-imparting material)

The adhesive coating liquid for current collector coat of the present invention may contain a tackiness imparting material. Polyhydric alcohol is preferably used as the tackiness imparting material, and specific examples thereof include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerin, triethylene glycol, tetraethylene glycol, trimethylolpropane, and the like. . These polyhydric alcohols can be used 1 type or in combination of 2 or more type. Among these, it is especially preferable to use glycerol or propylene glycol from a viewpoint of volatility and plasticity.

The content of the tackiness imparting material in the adhesive coating liquid for a current collector coat of the present invention is preferably 0.5 to 10 wt.%, more preferably 1 to 5 wt.%. When there is too much content of a tackifier, the performance of the lithium ion secondary battery obtained will deteriorate. Moreover, when there is too little content of a tackiness imparting material, desired tackiness cannot be provided.

(Adhesive coating solution for current collector coat)

The manufacturing method of the adhesive agent coating liquid for collector coating|coat of this invention is not specifically limited, Any means may be sufficient as long as each said solid component can be disperse|distributed in a dispersion medium. For example, a binder aqueous dispersion containing a binder, a surfactant and/or a tackifier used as necessary are mixed at once, and then a dispersion medium is added as necessary, and water is added to form a solid content of the dispersion. You may adjust the density|concentration. Moreover, you may add to the binder aqueous dispersion containing a binder in the state which melt|dissolved or disperse|distributed at least one of a surfactant and a tackiness-imparting material in water.

Although the viscosity of the adhesive coating liquid for current collector coating varies depending on the application method, from the viewpoint of forming a uniform adhesive layer on the current collector, preferably 10 to 10,000 mPa·s, more preferably 20 to 5,000 mPa·s, more preferably 50 to 2,000 mPa·s.

In addition, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating is less than 0.3 wt.%, preferably less than 0.2 wt.%, and more preferably less than 0.1 wt.%, based on the solid content. Here, the amount of agglomerates generated in the marron type mechanical stability test is the ratio (wt.%) of the agglomerate amount (residue) to the solid content in the sample, and the agglomerate amount is a 100 mesh wire mesh It is obtained by collecting and drying. When the amount of aggregates generated in the Marron-type mechanical stability test is too large, aggregates are generated during coating of the adhesive coating liquid for current collector coat.

Moreover, the contact angle with respect to copper foil of the adhesive agent coating liquid for collector coating|coat is less than 60 degrees, Preferably it is less than 50 degrees, More preferably, it is less than 45 degrees. When the contact angle is too large, coating cannot be performed because the adhesive coating liquid for current collector coat is repelled at the time of coating.

In addition, the measurement result in the loop tack test of the adhesive coating liquid for collector coats can be measured by the loop tack test performed in the state which coated the adhesive coating liquid for collector coatings on the collector, 0.5 N/25 mm or more, preferably 1.0 N/25 mm or more, and more preferably 2.0 N/25 mm or more. Here, the measurement result of the loop tack test was calculated|required by measuring the loop tack in 25 degreeC atmosphere according to FINAT-1991 FTM-9 (Quick-stick tack measurement). In addition, for the test panel in the said loop tack test, the polyethylene terephthalate film which apply|coated the adhesive coating liquid for collector coatings of this invention to the thickness of 2 micrometers was used.

When the measurement result in the loop tack test is too small, the adhesive force of the adhesive bond layer formed by the adhesive agent coating liquid for collector coatings will fall.

(Current collector with adhesive layer formed)

By coating the adhesive coating liquid for current collector coat of the present invention on the current collector, a current collector with an adhesive layer in which an adhesive layer is formed on the current collector can be obtained.

The material of the current collector is, for example, a metal, carbon, a conductive polymer or the like, and a metal is preferably used. As a metal for electrical power collectors, aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, another alloy, etc. are used normally. Among them, it is preferable to use copper, aluminum or an aluminum alloy from the viewpoint of conductivity and withstand voltage properties.

The thickness of the current collector is preferably 5 to 100 µm, more preferably 8 to 70 µm, still more preferably 10 to 50 µm.

The coating method in particular of an adhesive bond layer is not restrict|limited. For example, an adhesive layer is formed on the current collector by a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a die coating method, a brush application, or the like. Moreover, after forming an adhesive bond layer on a release paper, you may transcribe|transfer this to an electrical power collector.

In addition, the coated adhesive layer may be dried, and examples of the drying method include drying with warm air, hot air, low-humidity air, vacuum drying, and a drying method by irradiation with (far) infrared rays or electron beams. Among these, the drying method by hot air and the drying method by irradiation of far-infrared rays are preferable. The drying temperature and drying time are preferably a temperature and time at which the solvent in the current collector coat adhesive coating liquid applied on the current collector can be completely removed, and the drying temperature is usually 50 to 300°C, preferably 80 to 250°C. Drying time is 2 hours or less normally, Preferably they are 5 second - 30 minutes. Moreover, it is preferable that the adhesive bond layer formed by the adhesive agent coating liquid for collector coatings of this invention has a tack, without heating after coating to a collector.

The thickness of the adhesive layer is 0.5 to 5 µm, preferably 0.5 to 4 µm, particularly preferably 0.5 to 3 µm, from the viewpoint of obtaining an electrode having good adhesion to an electrode active material layer described later and having a low resistance. am.

The adhesive layer has a composition according to the solid content composition of the adhesive coating liquid for current collector coat, and contains a binder, a surfactant and a tackifier used as necessary.

(electrochemical element electrode)

An electrochemical device electrode can be obtained by forming an electrode active material layer on the current collector on which the adhesive layer is formed. Although the formation method of an electrode active material layer is not specifically limited, Using the composite particle containing an electrode active material, it is preferable to laminate|stack an electrode active material layer on the electrical power collector in which the adhesive bond layer was formed.

When the electrode active material layer is laminated on the current collector on which the adhesive layer is formed, the composite particles may be molded into a sheet shape and then laminated on the current collector on which the adhesive layer is formed, but the composite particles are directly pressed on the current collector on which the adhesive layer is formed. A method of molding is preferred. As a method of pressure molding, for example, using a roll type pressure forming apparatus equipped with a pair of rolls, while conveying the current collector with an adhesive layer formed thereon to a roll, roll type pressure forming of the composite particles with a supply device such as a screw feeder By supplying the device to the roll press molding method of molding the electrode active material layer on the current collector on which the adhesive layer is formed, or by dispersing the composite particles on the current collector on which the adhesive layer is formed, the composite particles are smoothed with a blade or the like to adjust the thickness, , a method of molding with a pressurizing device, a method of filling a mold with composite particles, and pressurizing a mold for molding. Among these, the roll pressure forming method is preferable. In particular, since the composite particle of the present invention has high fluidity, its high fluidity enables molding by roll press molding, thereby improving productivity.

The roll temperature at the time of roll press molding is preferably 25-200 degreeC, More preferably, 50-150 degreeC from a viewpoint of making the adhesiveness of the electrical power collector with an electrode active material layer and the adhesive bond layer a sufficient thing. , more preferably 80 to 120°C. Moreover, from a viewpoint which can improve the uniformity of the thickness of an electrode active material layer as for the press line pressure between rolls at the time of roll press molding, Preferably it is 10-1000 kN/m, More preferably, it is 200-900 kN/m, More preferably, it is 300-600 kN/m. Moreover, the shaping|molding speed at the time of roll press forming becomes like this. Preferably it is 0.1-20 m/min, More preferably, it is 4-10 m/min.

Moreover, in order to eliminate the dispersion|variation in the thickness of the shape|molded electrochemical element electrode, raise the density of an electrode active material layer, and to aim at high capacity|capacitance, you may perform post-pressurization further as needed. As for the method of post-pressurization, the press process with a roll is preferable. In a roll press process, two columnar rolls are arranged up and down in parallel at a narrow space|interval, each is rotated in the opposite direction, and it presses by making an electrode mesh|engage in the meantime. In this case, the roll may temperature-control, such as heating or cooling, as needed.

(composite particles)

As a composite particle, it is obtained by granulating using an electrode active material, a binder, and other components, such as a water-soluble polymer and electrically conductive agent added as needed. The method for producing the composite particles is not particularly limited, but using a slurry for composite particles containing other components such as an electrode active material, a binder, and an optionally added conductive agent, spray drying granulation method, rolling layer granulation method, compression type granulation method, It can be obtained by manufacturing methods such as agitated granulation method, extrusion granulation method, crushed granulation method, fluidized bed granulation method, fluidized bed multifunctional granulation method, and melt granulation method. Among these, the spray-drying granulation method is preferable from a viewpoint of being able to manufacture a composite particle comparatively easily.

(Slurry for composite particles)

The slurry for composite particles used for the production of composite particles is formed by dispersing or dissolving an electrode active material, a conductive agent, a binder, and other components added as necessary in a dispersion medium.

(electrode active material)

As an electrode active material for lithium ion secondary battery positive electrodes in case an electrochemical element is a lithium ion secondary battery (positive electrode active material), the metal oxide which can dope and dedope lithium ion reversibly is mentioned. As such a metal oxide, lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, etc. are mentioned, for example. In addition, the positive electrode active material illustrated above may be used independently according to a use suitably, and may be used in mixture of multiple types.

In addition, as an active material (negative electrode active material) of a negative electrode as a counter electrode of a lithium ion secondary battery positive electrode, For example, low crystalline carbon (amorphous carbon), such as graphitizable carbon, graphitizable carbon, pyrolysis carbon, and alloy-based materials such as graphite (natural graphite, artificial graphite), tin and silicon, and oxides such as silicon oxide, tin oxide, and lithium titanate. In addition, the negative electrode active material illustrated above may be used independently according to a use suitably, and may be used in mixture of multiple types.

It is preferable that the shape of the electrode active material for lithium ion secondary battery electrodes was established in a granular form. When the shape of the particles is granular, a higher density electrode can be formed at the time of electrode molding.

As for the volume average particle diameter of the electrode active material for lithium ion secondary battery electrodes, a positive electrode and a negative electrode are 0.1-100 micrometers normally, Preferably it is 0.5-50 micrometers, More preferably, it is 0.8-30 micrometers.

(challenge)

Specific examples of the conductive agent used in the present invention include conductive carbon blacks such as furnace black, acetylene black, and Ketjen Black (registered trademark of Akzo Nobel Chemicals Vesloten Bennot Shop). Among these, acetylene black and furnace black are more preferable.

These electrically conductive agents can be used individually or in combination of 2 or more types.

(Binder)

As the binder used in the production of the composite particles, the same binder as the binder used in the above-described adhesive coating solution for current collector coat can be used.

(other ingredients)

The slurry for composite particles may contain other components, such as a dispersing agent, as needed. Specific examples of the dispersant include cellulose polymers such as carboxymethyl cellulose and methyl cellulose, and ammonium or alkali metal salts thereof. These dispersants can be used individually or in combination of 2 or more type, respectively.

(Preparation of composite particles)

The composite particles are obtained by, for example, spray-drying the above-mentioned slurry containing an electrode active material, a conductive agent, a binder, and other components added as needed. Here, the composite particle contains at least an electrode active material, a conductive agent, and a binder, but each of the above does not exist as an independent particle, but two or more components containing an electrode active material and a binder as constituent components. to form 1 particle by Specifically, a plurality of the individual particles of the two or more components are combined to form secondary particles, and a plurality (preferably several to several tens) of the electrode active material is bound by a binder to form particles, It is preferable to have

The average particle diameter of the composite particles is preferably 0.1 to 200 µm, more preferably 1-150 µm, still more preferably 10-80 µm from the viewpoint of easily obtaining an electrode active material layer having a desired thickness. In addition, in this invention, an average particle diameter is a volume average particle diameter calculated by measuring with a laser diffraction type particle size distribution analyzer (for example, SALD-3100; Shimadzu Corporation make).

(electrochemical element)

As a usage aspect of an electrochemical element electrode, the lithium ion secondary battery which used such an electrode, a lithium ion capacitor, etc. are mentioned, A lithium ion secondary battery is preferable. For example, a lithium ion secondary battery uses the electrochemical element electrode obtained as mentioned above for at least one of a positive electrode and a negative electrode, and is further equipped with a separator and electrolyte solution.

(separator)

As a separator, For example, the porous film or nonwoven fabric which contains polyolefin resin, such as polyethylene and a polypropylene, and aromatic polyamide resin; porous resin coat containing inorganic ceramic powder; etc. can be used.

The thickness of the separator is preferably 0.5 to 40 µm, more preferably 1 µm, from the viewpoint of reducing resistance by the separator in the lithium ion secondary battery and excellent workability in manufacturing the lithium ion secondary battery. It is 30 micrometers, More preferably, it is 1-25 micrometers.

(electrolyte)

Although the electrolyte solution 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) and lithium salts such as 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 is easily soluble in a solvent and exhibits a high degree of 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 wt.% or more, preferably 5 wt.% or more, and usually 30 wt.% or less, preferably 20 wt.% or less with respect to the electrolyte solution. Even if the amount of the supporting electrolyte is too small or too large, the ionic conductivity is lowered and the charging and discharging characteristics of the battery are lowered.

Although it will not specifically limit as a solvent used for electrolyte solution, As long as it dissolves a supporting electrolyte, 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; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide; is used Since it is easy to obtain especially high ionic conductivity and the operating temperature range is wide, dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, and methyl ethyl carbonate are preferable. These can be used individually or in mixture of 2 or more types. Moreover, it is also possible to make electrolyte solution contain an additive, and to use it. Moreover, as an additive, carbonate type compounds, such as vinylene carbonate (VC), are preferable.

Examples of the electrolytic solution other than the above include a gel polymer electrolyte in which an electrolytic solution is impregnated with a polymer electrolyte such as polyethylene oxide or polyacrylonitrile, and inorganic solid electrolytes such as lithium sulfide, LiI, Li ₃ N, Li ₂ SP ₂ S ₅ glass ceramics. can be heard

A lithium ion secondary battery is obtained by overlapping a negative electrode and a positive electrode through a separator, winding this according to the shape of a battery, bending, putting it in a battery container, injecting electrolyte solution into a battery container, and sealing. In addition, if necessary, an overcurrent protection element such as an expanded metal, a fuse, or a PTC element, a lead plate, or the like may be inserted to prevent an increase in pressure inside the battery and prevention of overcharge/discharge. The shape of the battery may be any of a laminated cell type, a coin type, a button type, a sheet type, a cylindrical shape, a square shape, and a flat shape.

ADVANTAGE OF THE INVENTION According to the adhesive agent coating liquid for collector coatings of this invention, the electrochemical element electrode which has favorable performance also at the time of long shaping|molding can be manufactured.

Example

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples, and may be arbitrarily changed and implemented without departing from the spirit and equivalents of the present invention. . In addition, in the following description, "%" and "part" indicating a quantity are based on weight, unless otherwise specified.

In an Example and a comparative example, evaluation of peeling strength and capacity|capacitance retention was performed as follows, respectively.

<peel strength>

Among the current collectors with an adhesive layer obtained in Examples and Comparative Examples, a lithium ion secondary battery electrode (negative electrode in Example 7, other examples and In the comparative example, the positive electrode) was cut out into the rectangle of length 100mm and width 10mm, and it was set as the test piece. This test piece was affixed to the cellophane tape fixed to the test stand. At the time of pasting, the surface by the side of an electrode active material layer was turned down, and the surface by the side of an electrode active material layer and the adhesive surface of a cellophane tape were made to contact. As a cellophane tape, what is prescribed|regulated to JISZ1522 was used.

Then, the stress at the time of peeling by pulling one end of an electrical power collector vertically upward at 50 mm/min of tensile speed was measured. This measurement was performed 3 times, the average value was calculated|required, and the said average value was made into peeling strength. It shows that the binding force with respect to the electrical power collector of an electrode active material layer is large, ie, adhesive strength is large, so that a peeling strength is large.

A: 3.0 N/m or more

B : 2.0 N/m or more, 3.0 N/m or less

C : 1.0 N/m or more, 2.0 N/m or less

D: less than 1.0 N/m

<Capacity retention rate (final 50 m and first 50 m)>

Among the current collectors with an adhesive layer obtained in Examples and Comparative Examples, for lithium ion secondary batteries manufactured using the final 50 m and the first 50 m, 4.2 V was The charging/discharging cycle test was performed by charging with a constant current until it became a constant current, then charging with a constant voltage, and then discharging to 3.0V with a constant current of 0.5C. The charge/discharge cycle test was performed up to 100 cycles. The ratio of the discharge capacity at the 100th cycle to the initial discharge capacity was obtained as the capacity retention ratio. In each Example and Comparative Example, 10 samples were prepared, and the following reference|standard judged the thing with the smallest capacity retention rate among 10 samples. It shows that the capacity|capacitance decrease by repeated charging/discharging is so small that this value is large.

A: Capacity retention of 90% or more

B: Capacity retention ratio of 80% or more and less than 90%

C: Capacity retention ratio of 70% or more and less than 80%

D: Capacity retention ratio of 60% or more and less than 70%

E: Capacity retention rate is less than 60%

Moreover, the Marron type mechanical stability test, the loop tack test, and the contact angle measurement were implemented about the adhesive agent coating liquid for collector coatings obtained in the Example and the comparative example as follows.

<Marron type mechanical stability test>

After adjusting the pH of the adhesive coating liquid for current collector coating obtained by the Example and the comparative example to 8±0.1 and filtering with a 100 mesh wire mesh, the solid content concentration was adjusted to 30 %. After filtration through a 100 mesh wire mesh, it was subjected to a Marron type mechanical stability test. The conditions were 1000 rpm in rotation speed, 15 kg in weight, and 10 minutes. After the Marron-type mechanical stability test, the adhesive coating solution for current collector coating is filtered through a 100 mesh wire mesh, and the aggregates collected by filtration on the wire mesh are dried and weighed to determine the amount of aggregates generated, and the published adhesive for current collector coating The ratio (%) with respect to the solid content weight of the coating liquid was calculated|required.

<Loop tack test>

According to FINAT-1991 FTM-9 (Quick-stick tack measurement), the loop tack of the current collector coated with the current collector coating adhesive coating solution obtained in Examples and Comparative Examples in an atmosphere of 25° C. is measured, and tackiness is evaluated. did The higher the value, the better the tackiness.

<Measurement of contact angle>

The contact angle of the adhesive coating liquid for current collector coat obtained in the Example and the comparative example was observed using "DMs-400" by Kyowa Interface Science Co., Ltd. product. Specifically, 2 µL of the adhesive coating solution for current collector coat was dripped onto the electrolytic surface of an electrolytic copper foil (manufactured by Furukawa Denko Co., Ltd. product name “NC-WS” with a thickness of 20 µm). The droplet 1 minute after dripping was observed using the measuring apparatus from the horizontal direction. From the observed image, the contact angle between the electrolytic copper foil and the adhesive coating liquid for current collector coating was calculated by the θ/2 method.

The adhesive coating liquid for current collector coats of an Example and a comparative example, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were produced as follows.

(Example 1)

(Preparation of binder)

300 parts of ion-exchanged water, 93.8 parts of n-butyl acrylate, 2 parts of acrylonitrile, 1.0 part of allylglycine ether, 2.0 parts of itaconic acid, 1.2 parts of N-methylolacrylamide, and t as a molecular weight modifier in an autoclave provided with a stirrer -Add 0.05 parts of dodecyl mercaptan and 0.3 parts of potassium persulfate as a polymerization initiator, after sufficiently stirring, heating to 70° C. to polymerize, and a particulate binder containing an acrylic polymer having a solid content concentration of 40% as a binder (acrylic late binder) was obtained. The polymerization conversion rate calculated|required from solid content concentration was about 99 %. Moreover, Tg of the obtained particulate-form binder was -20 degreeC.

(Preparation of adhesive coating solution for current collector coat)

40 wt.% of the binder in terms of solid content, 0.5 wt.% of dispanol TOC (manufactured by Nichiyu Corporation), a nonionic surfactant, as a surfactant, and propylene glycol (hereinafter referred to as “PG”) as a tackifier A binder, a surfactant, a tackifier, and water were mixed to obtain an adhesive coating liquid for a current collector coating. The amount of aggregates generated in the Marron type mechanical stability test of the obtained adhesive coating liquid for current collector coating was 0.05 wt.%, and the contact angle with respect to the copper foil was 30°.

(Preparation of composite particles)

92 parts of lithium cobaltate (LiCoO ₂ , hereinafter referred to as “LCO”) (particle diameter: 6 μm) as a positive electrode active material, 2.0 parts of the above binder in terms of solid content, acetylene black as a conductive agent (Denka Chemical Industry Co., Ltd.) Black powder product: particle diameter 35 nm, specific surface area 68 m 2 / g) 5.0 parts, as a dispersant 1.5% aqueous solution of carboxymethyl cellulose (DN-800H: manufactured by Daicel Chemical Industry Co., Ltd.) 1.0 parts in terms of solid content, mixed, and added The furnace ion-exchange water was added so that solid content concentration might be set to 40 %, it mixed and dispersed, and the slurry for composite particles for positive electrodes was obtained. This slurry for composite particles for positive electrode was prepared by using a spray dryer (manufactured by Okawara Chemical Co., Ltd.) and using a rotary disk type atomizer (diameter 65 mm) at a rotation speed of 25,000 rpm, a hot air temperature of 150° C., and a particle recovery outlet. Spray-drying granulation was performed by making temperature into 90 degreeC, and the composite particle was obtained. The average volume particle diameter of this composite particle was 50 micrometers.

(Formation of adhesive layer)

An adhesive coating solution for current collector coating was applied to an aluminum current collector having a thickness of 10 μm by a gravure coating method at a molding speed of 20 m/min for 1000 m, dried at 120° C. for 2 minutes, and then on the current collector. A current collector with an adhesive layer in which an adhesive layer having a thickness of 1.2 μm was formed was obtained. The loop tack of the adhesive bond layer in the electrical power collector with the obtained adhesive bond layer was 6 N/25 mm.

(Production of lithium ion secondary battery positive electrode)

The current collector with the adhesive layer formed thereon is conveyed at a speed of 2 m/min, and the positive electrode active material layer is heated with a roll (roll temperature 100° C., press linear pressure 4 kN/cm) of a roll press machine (press-cutting rough surface hot roll, manufactured by Hirano Kien Kogyo Co., Ltd.) It shape|molded in sheet form on the electrical power collector with an adhesive bond layer, and obtained the 60-micrometer-thick lithium ion secondary battery positive electrode.

(Production of negative electrode slurry and lithium ion secondary battery negative electrode)

As a negative electrode active material, artificial graphite (average particle diameter: 24.5 μm, graphite interlayer distance (interface spacing (d value) of (002) plane by X-ray diffraction method (d value): 0.354 nm)) 96 parts, styrene-butadiene copolymer latex (BM-400B) ) of 3.0 parts in terms of solid content, and 1.0 parts in terms of solid content of a 1.5% aqueous solution of carboxymethyl cellulose (DN-800H: manufactured by Daicel Chemical Industry Co., Ltd.) as a dispersing agent in terms of solid content, and further mixed with ion-exchanged water to a solid content concentration of 50% was added, mixed and dispersed to obtain a negative electrode slurry.This negative electrode slurry was applied to 18 µm thick copper foil, dried at 120 ° C. for 30 minutes, and then roll pressed to obtain a 50 µm thick negative electrode.

(Preparation of the separator)

A single-layer polypropylene separator (65 mm in width, 500 mm in length, 25 µm in thickness, manufactured by a dry method, porosity 55%) was cut out into a square of 5 × 5 cm 2 .

(Manufacture of lithium ion secondary battery)

As an exterior of the battery, an aluminum packaging material exterior was prepared. The lithium ion secondary battery positive electrode obtained above was cut out in a 4x4 cm<2> square, and it has arrange|positioned so that the surface by the side of an electrical power collector may contact|connect the aluminum wrapping material exterior. The square separator obtained above was arrange|positioned on the surface of the positive electrode active material layer of a lithium ion secondary battery positive electrode. Moreover, the lithium ion secondary battery negative electrode obtained above was cut out in the square of 4.2x4.2cm<2>, and it arrange|positioned on the separator so that the surface by the side of a negative electrode active material layer may face a separator. Further, a LiPF ₆ solution having a concentration of 1.0 M containing 2.0% of vinylene carbonate was filled. The solvent of this LiPF ₆ solution is a mixed solvent of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) (EC/EMC = 3/7 (volume ratio)). Moreover, in order to seal the opening of the aluminum wrapping material, heat-sealing was performed at 150 degreeC, the aluminum exterior was closed, and the laminated lithium ion secondary battery (laminated cell) was manufactured.

(Example 2)

In the production of the binder, the binder was prepared in the same manner as in Example 1 except that the amount of itaconic acid to be used was 1 part. Tg of the particulate-form binder obtained in Example 2 was -20 degreeC. Except having used this binder, manufacture of the adhesive agent coating liquid for current collector coats, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were manufactured similarly to Example 1.

Moreover, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 2 was 0.1 wt.%, the contact angle with respect to the copper foil was 30°, and the roof tack was 5 N/25 mm.

(Example 3)

In the preparation of the adhesive coating solution for current collector coating, as in Example 1, except that a binder, a surfactant, a tackifier and water were mixed so that the concentration of dispanol TOC as a surfactant was 0.1 wt.% Manufacture of the adhesive agent coating liquid for collector coatings, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and manufacture of the lithium ion secondary battery were performed.

Moreover, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 3 was 0.05 wt.%, the contact angle to copper foil was 50°, and the roof tack was 5 N/25 mm.

(Example 4)

Production of the binder WHEREIN: Tg produced the binder similarly to Example 1 except having obtained the particulate-form binder whose Tg is 0 degreeC. Similar to Example 1 using this binder, manufacture of the adhesive agent coating liquid for electrical power collector coats, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were manufactured.

Moreover, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 4 was 0.05 wt.%, the contact angle with respect to the copper foil was 30°, and the roof tack was 1 N/25 mm.

(Example 5)

In the preparation of the adhesive coating solution for current collector coating, binder, surfactant, and tackiness are imparted so that the concentration of dispanol TOC as a surfactant is 0.2 wt.% and propylene glycol as a tackifier is 2 wt.% Except having mixed the ash and water, manufacture of the adhesive agent coating liquid for collector coatings, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were manufactured similarly to Example 4.

In addition, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 5 was 0.05 wt.%, the contact angle to copper foil was 30°, and the roof tack was 6 N/25 mm.

(Example 6)

In the preparation of the adhesive coating solution for current collector coating, glycerin is used as a tackifier, so that the concentration of dispanol TOC as a surfactant is 0.8 wt.% and the concentration of glycerin as a tackifier is 1 wt.% Preparation of adhesive coating liquid for current collector coating, lithium ion secondary battery positive electrode, lithium ion secondary battery negative electrode, and lithium ion secondary battery production as in Example 1 except that the binder, surfactant, tackifier and water were mixed was carried out.

Moreover, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 6 was 0.05 wt.%, the contact angle with respect to the copper foil was 30°, and the roof tack was 5 N/25 mm.

(Example 7)

(Preparation of adhesive coating solution for current collector coat)

In the preparation of the adhesive coating solution for current collector coating, as a binder, instead of the above binder, styrene-butadiene copolymer latex (BM-400B) (hereinafter sometimes referred to as “SBR-based binder”) is used, and the interface A binder, surfactant, tackifier and water were mixed so that the dispanol TOC as an activator was 0.8 wt.% and propylene glycol as the tackifier material was 1 wt.% to obtain an adhesive coating solution for current collector coating.

Moreover, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 7 was 0.05 wt.%, the contact angle to copper foil was 30°, and the roof tack was 8 N/25 mm.

(Preparation of composite particles)

92 parts of artificial graphite as a negative electrode active material (average particle diameter: 24.5 μm, graphite interlayer distance (interplanar spacing (d value) of (002) planes by X-ray diffraction method: 0.354 nm), the styrene-butadiene copolymer latex (BM-) 400B) in terms of solid content, 2.0 parts in terms of solid content, and 1.0 parts of a 1.5% aqueous solution of carboxymethyl cellulose (DN-800H: manufactured by Daicel Chemical Industries, Ltd.) as a dispersant in terms of solid content, in terms of solid content, and additionally ion-exchanged water with a solid content concentration of 40 %, mixed and dispersed to obtain a slurry for composite particles for negative electrodes.Use a spray dryer (manufactured by Okawara Chemical Co., Ltd.) for this slurry for composite particles for negative electrodes, and use a rotary disk type atomizer (diameter 65 mm) was used, spray-drying granulation was performed with a rotation speed of 25,000 rpm, a hot air temperature of 150° C., and a temperature of the particle recovery outlet of 90° C. to obtain composite particles.The composite particles had an average volumetric particle diameter of 50 µm.

(Production of slurry for positive electrode and positive electrode of lithium ion secondary battery)

Polyvinylidene fluoride (PVDF; "KF-1100" manufactured by Kureha Chemical Co., Ltd.) as a positive electrode binder in 92 parts of LiCoO ₂ (hereinafter, sometimes abbreviated as "LCO") as a positive electrode active material in a solid content of 2 parts Further, 6 parts of acetylene black ("HS-100" manufactured by Denki Chemical Industry Co., Ltd.) and 20 parts of N-methylpyrrolidone were added and mixed with a planetary mixer to obtain a slurry for positive electrodes. After apply|coating this slurry for positive electrodes to 18-micrometer-thick aluminum foil and making it dry at 120 degreeC for 30 minutes, it roll-pressed and obtained the 60-micrometer-thick lithium ion secondary battery positive electrode.

(Manufacture of lithium ion secondary battery)

The same separator as in Example 1 was prepared, and using the lithium ion secondary battery negative electrode and the lithium ion secondary battery positive electrode obtained in Example 7, in the same procedure as in Example 1, a laminate type lithium ion secondary battery (laminate type cell) ) was prepared.

(Example 8)

In the preparation of the adhesive coating solution for the current collector coat, a binder, a surfactant, a tackifier, and water were mixed using polyethylene oxide instead of the binder as a binder, and the same as in Example 1 was used. Manufacture of the adhesive agent coating liquid for all coats, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and manufacture of the lithium ion secondary battery were performed.

In addition, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 8 was 0 wt.%, the contact angle with respect to the copper foil was 35°, and the roof tack was 2 N/25 mm.

(Comparative Example 1)

In the preparation of the binder, the binder was prepared in the same manner as in Example 1, except that itaconic acid was not used. Tg of the particulate-form binder obtained in Comparative Example 1 was -20 degreeC. Moreover, using this binder, manufacture of the adhesive agent coating liquid for collector coatings WHEREIN: The adhesive agent coating liquid for collector coatings was manufactured without using a tackiness imparting material. Moreover, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were manufactured similarly to Example 1 except having used the adhesive agent coating liquid for collector coatings obtained in Comparative Example 1.

In addition, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Comparative Example 1 was 0.5 wt.%, the contact angle with respect to the copper foil was 30°, and the roof tack was 4 N/25 mm.

(Comparative Example 2)

In the preparation of the adhesive coating solution for the current collector coating, the preparation of the adhesive coating solution for the current collector coating was carried out in the same manner as in Example 1 except that a binder, a tackifier and water were mixed without using a surfactant, lithium ion The secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were manufactured.

Moreover, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Comparative Example 2 was 0.1 wt.%, the contact angle to copper foil was 60°, and the roof tack was 4 N/25 mm.

(Comparative Example 3)

Manufacture of a binder WHEREIN: Tg produced the binder similarly to Example 1 except having obtained the particulate-form binder whose Tg is 10 degreeC. Further, using this binder, a binder, a surfactant, a tackifier and water are mixed so that the dispanol TOC as a surfactant is 0.05 wt.% and propylene glycol as a tackifier is 1 wt.%. The adhesive coating liquid for all coats was manufactured. Except having used this adhesive agent coating liquid for collector coatings, similarly to Example 1, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were manufactured.

Moreover, the amount of aggregates generated in the Marron type mechanical stability test of the adhesive coating liquid for current collector coating obtained in Comparative Example 3 was 0.1 wt.%, the contact angle to the copper foil was 80°, and the roof tack was 0.1 N/25 mm.

As shown in Table 1, as an adhesive coating solution for a current collector coat containing a binder and water, the amount of agglomerates generated in the Marron-type mechanical stability test of the coating solution is less than 0.3 wt.% with respect to the solid content, and the copper foil The peel strength of the lithium ion secondary battery electrode using the adhesive coating solution for current collector coating with a contact angle of less than 60° and a measurement result in the loop tack test of 0.5 N/25 mm or more is good, and this adhesive coating for the current collector coating The capacity retention rate of the lithium ion secondary battery including the lithium ion secondary battery electrode using the liquid was good at both the initial 50 m and the final 50 m.

Claims (5)

An adhesive coating solution for a current collector coat containing a binder and water, comprising:
The pH of the coating solution is adjusted to 8±0.1, filtered through a 100 mesh wire mesh, the solid content concentration is adjusted to 30 wt.%, and this is filtered through a 100 mesh wire mesh, rotation speed 1000 rpm, weight 15 kg, 10 Subject to the marron-type mechanical stability test under the condition of minutes, the coating solution after the marron-type mechanical stability test is filtered through a 100 mesh wire mesh, and the aggregates collected by filtration on the wire mesh are dried and weighed, and the amount of aggregates generated is disclosed. (供試) the ratio to the solid weight of the coating solution is less than 0.3 wt.%,
2 μl of the coating solution was dropped onto the electrolytic surface of the electrodeposited copper foil, and the droplet after 1 minute after dropping was calculated from the image observed from the horizontal direction using a contact angle meter, the electrodeposited copper foil calculated by the θ/2 method, and the The contact angle of the coating solution is less than 60°,
According to FINAT-1991 FTM-9 (Quick-stick tack measurement), the result of measuring the loop tack in an atmosphere of 25 ° C. of the current collector coated with the coating solution is 0.5 N/25 mm or more, the current collector coating adhesive coating liquid. The method of claim 1,
An adhesive coating solution for a current collector coat, wherein the binder is a particulate binder. 3. The method of claim 2,
The glass transition temperature of the said particulate-form binder is -40 degreeC or more and 10 degrees C or less, The adhesive coating liquid for electrical power collector coatings. The method of claim 1,
An adhesive coating solution for a current collector coating, comprising a surfactant, wherein the concentration of the surfactant is 0.1 wt.% or more and less than 3 wt.%. 5. The method according to any one of claims 1 to 4,
Adhesive coating liquid for current collector coat containing a tackiness imparting material.