WO2015115177A1

WO2015115177A1 - Liquid adhesive coating for coating collector

Info

Publication number: WO2015115177A1
Application number: PCT/JP2015/050754
Authority: WO
Inventors: 卓松村
Original assignee: 日本ゼオン株式会社
Priority date: 2014-01-29
Filing date: 2015-01-14
Publication date: 2015-08-06
Also published as: KR102384939B1; JPWO2015115177A1; JP6471697B2; CN105814720A; KR20160114044A; CN105814720B

Abstract

　A liquid adhesive coating for coating a collector, the liquid adhesive coating containing a binding agent and water, wherein the amount of aggregates produced during Maron mechanical stability testing of the liquid coating is less than 0.3 wt% of the solid content, the contact angle with respect to copper foil is less than 60°, and the result of measurement using loop tack testing is 0.5 N/25 mm.

Description

Adhesive coating solution for current collector coating

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

Electrochemical elements such as lithium ion secondary batteries that are small and lightweight, have high energy density, and can be repeatedly charged and discharged are rapidly expanding their demands by taking advantage of their characteristics. Lithium ion secondary batteries are used in fields such as mobile phones, notebook personal computers, and electric vehicles because of their relatively high energy density.

These electrochemical elements are required to be further improved in accordance with expansion and development of applications, such as lowering resistance, increasing capacity, improving mechanical properties and productivity. Under such circumstances, there has been a demand for a more productive manufacturing method for electrochemical element electrodes, and various improvements have been made regarding a manufacturing method capable of high-speed molding and a material for electrochemical element electrodes suitable for the manufacturing method. It has been broken.

Electrochemical element electrodes are usually formed by laminating an electrode active material layer formed by binding an electrode active material and a conductive agent used as necessary with a binder on a current collector. It is. As a method for forming such an electrode active material layer, Patent Documents 1 and 2 obtain and obtain a particulate electrode material by spray drying a slurry containing an electrode active material, rubber particles and a dispersion medium. Disclosed is a method of forming an electrode active material layer using an electrode material.

Japanese Patent No. 4219705 JP 2007-18874 A

Incidentally, in order to improve the adhesion between the electrode active material layer and the current collector, an intermediate layer such as an adhesive layer is provided between the electrode active material layer and the current collector. However, when an electrode active material layer is formed as in the methods disclosed in Patent Documents 1 and 2 in a portion where a coating liquid for providing an adhesive layer is not applied, the resistance of the battery increases and the capacity is maintained. The battery performance deteriorates, for example, the rate decreases.
In addition, in the technique described in Patent Document 1, when preparing the slurry, the viscosity of the slurry is low because no viscosity modifier is used, and the binder is localized on the surface in the particulate electrode material. The obtained particulate electrode material was inferior in fluidity. For this reason, there is a problem in moldability, such as inability to manufacture an electrode having a uniform film thickness.
Moreover, when manufacturing an electrode, for example, a long current collector wound in a roll shape is drawn out, and an electrode active material layer is formed on the current collector. Therefore, it is required to produce an electrode in which a uniform electrode active material layer is formed on a long current collector. However, Patent Documents 1 and 2 did not describe long formability.
The objective of this invention is providing the adhesive agent coating liquid for collector coating which can manufacture the electrochemical element electrode which has a favorable performance also at the time of long shaping | molding.

As a result of intensive studies, the present inventor has found that the above object can be achieved by using an adhesive coating liquid for current collector coating having predetermined physical property values, and has completed the present invention.

That is, according to the present invention,
(1) An adhesive coating solution for a current collector coating containing a binder and water, wherein the amount of agglomerates generated in the Marlon mechanical stability test of the coating solution is less than the solid content. 3 wt. %, The contact angle 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,
(2) The adhesive coating liquid for current collector coating according to (1), wherein the binder is a particulate binder,
(3) The adhesive coating liquid for current collector coating according to (2), wherein the particulate binder has a glass transition temperature of −40 ° C. or higher and 10 ° C. or lower,
(4) A surfactant is included, and the concentration of the surfactant is 0.1 wt. % Or more and 3 wt. % Adhesive coating liquid for current collector coating according to any one of (1) to (3),
(5) The adhesive coating liquid for a current collector coating according to any one of (1) to (4), which contains a tackiness-imparting material.

According to the adhesive coating liquid for current collector coating according to the present invention, an electrochemical element having good performance can be produced.

Hereinafter, the adhesive coating liquid for current collector coating of the present invention will be described. The current collector coat adhesive coating solution of the present invention is a current collector coat adhesive coating solution containing a binder and water, and in the Marlon mechanical stability test of the coating solution The amount of aggregates generated is 0.3 wt. %, 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. Note that “wt.%” Is synonymous with “wt%”.

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

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

Among these, a diene polymer or an acrylic polymer is preferable because of excellent adhesion between the current collector and the electrode active material layer. In addition, since the adhesive layer obtained from the current collector coating adhesive coating solution is used in the positive electrode and the negative electrode, high redox stability is required, and in particular, the oxidation stability at the positive electrode is high. To acrylic polymers are most preferred.

(Diene polymer)
The diene polymer is a polymer containing monomer units obtained by polymerizing conjugated dienes such as butadiene and isoprene. The proportion of monomer units obtained by polymerizing conjugated diene in the diene polymer is usually 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more. Examples of the polymer include homopolymers of conjugated dienes such as polybutadiene and polyisoprene; and copolymers of monomers that are copolymerizable with conjugated dienes. 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, chlorostyrene, vinyltoluene, and t-butyl. Styrene monomers such as styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, chloromethyl styrene, hydroxymethyl styrene, α-methyl styrene and divinyl benzene; olefins such as ethylene and propylene; vinyl chloride and vinylidene chloride Halogen atom-containing monomers such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, etc .; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether; methyl vinyl ketone, ethyl vinyl Vinyl ketones such as ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; and heterocyclic ring-containing vinyl compounds such as N-vinyl pyrrolidone, vinyl pyridine, and vinyl imidazole.

(Acrylic polymer)
The acrylic polymer is a polymer containing a monomer unit obtained by polymerizing an acrylic ester and / or a methacrylic ester. The proportion of monomer units obtained by polymerizing acrylic acid ester and / or methacrylic acid ester in the acrylic polymer is usually 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more. . Examples of the polymer include homopolymers of acrylic acid esters and / or methacrylic acid esters, and copolymers with monomers copolymerizable therewith. Examples of the copolymerizable monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, and fumaric acid; two or more carbons such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane triacrylate. Carboxylates having carbon double bonds; styrene, chlorostyrene, vinyl toluene, t-butyl styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, chloromethyl styrene, hydroxymethyl styrene, α-methyl styrene, Styrene monomers such as divinylbenzene; Amide monomers such as acrylamide, N-methylol aquaylamide, acrylamide-2-methylpropanesulfonic acid; α, β- such as acrylonitrile and methacrylonitrile Saturated nitrile compounds; olefins such as ethylene and propylene; diene monomers such as butadiene and isoprene; monomers containing halogen atoms such as vinyl chloride and vinylidene chloride; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate Vinyl esters such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether; vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, isopropenyl vinyl ketone; N-vinyl pyrrolidone, vinyl Heterocycle-containing vinyl compounds such as pyridine and vinylimidazole can be mentioned.

Examples of the polymer used for the binder solution include hydroxyethyl cellulose (HEC), polyethylene glycol (PEG), polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and polyoxyethylene polyoxypropylene block copolymer. Combined (PPP), polyacrylamide (PMMA), poly N-vinylformamide (PNVF), polyacrylic acid (PAA), sodium polyacrylate (PAA-Na), ammonium polyacrylate (PAA-NH4), polystyrene sulfonic acid Sodium (PSS-Na), sodium carboxymethylcellulose (CMC-Na), polyethyleneimine (PEI) and the like can be mentioned.

The binder used in the present invention is preferably obtained through a particulate metal removal step of removing particulate metals contained in the binder aqueous dispersion or the binder solution in the production process. When the content of the particulate metal component contained in the binder is 10 ppm or less, there is little concern about increased self-discharge due to internal short circuit of the battery or dissolution / precipitation during charging, improving the cycle characteristics and safety of the battery. To do.

The method for removing the particulate metal component from the binder aqueous dispersion or the binder solution in the particulate metal removal step is not particularly limited. For example, the removal method by filtration using a filtration filter, the removal method using a vibrating sieve, and centrifugation. And a method of removing by magnetic force. Especially, since the removal object is a metal component, the method of removing by magnetic force is preferable. The method for removing by magnetic force is not particularly limited as long as it is a method that can remove the metal component. However, in consideration of productivity and removal efficiency, it is preferable to place a magnetic filter in the binder production line. Is called.

Further, the binder preferably has a cationic group or an anionic group.
A cationic group is a group in which the substituent has cationic chemical functionality, and the substituent has the formula R ₁ R ₂ R ₃ R ₄ N ⁺ (A ⁻ ), wherein R ₁ is Is as follows.

R ₁ is of the formula —CH ₂ —CHOH—CH ₂ — or —CH ₂ —CH ₂ —, wherein R ₂ , R ₃ , R ₄ each independently represents 1-20 carbon atoms. Selected from alkyl or arylalkyl groups having A ⁻ is a halide ion, a sulfate ion, a phosphate ion, or a tetrafluoroborate ion.

When the binder is produced, a cationic group-containing ethylenically unsaturated monomer is copolymerized and then neutralized or quaternized as necessary, whereby a cationic group is contained in the binder. Can be contained. 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, di-t-butylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, dipropylaminopropyl (meth) acrylamide, diisopropylaminopropyl (Meth) acrylamide, dibutylaminopropyl (meth) acrylamide, diisobutylaminopropyl (meth) acrylamide, di-t-butylaminopropyl (Meth) acrylic acid ester or (meth) acrylamide having a dialkylamino group such as pill (meth) acrylamide; styrene having a dialkylamino group such as dimethylaminostyrene or dimethylaminomethylstyrene; 4-vinylpyridine, 2- Vinyl pyridines such as vinyl pyridine; N-vinyl heterocyclic compounds such as N-vinyl imidazole; acid neutralized products of monomers having amino groups such as amino ether vinyl ether and vinyl ethers such as dimethylaminoethyl vinyl ether; Quaternary ammonium salts; diallyl-type quaternary ammonium salts such as dimethyldiallylammonium chloride and diethyldiallylammonium chloride.

The anionic group is a group in which the substituent has an anionic chemical functionality. Examples of the anionic chemical functional group include carboxylate, sulfate, sulfonate, phosphate, phosphonate, or a mixture thereof. It is done.

When producing the binder, an anionic group can be contained in the binder by copolymerizing an anionic group-containing ethylenically unsaturated monomer. The anionic group-containing ethylenically unsaturated monomer is not particularly limited, and examples thereof include ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid; itaconic acid, maleic acid, fumaric acid, and butenetricarboxylic acid. Ethylenically unsaturated polycarboxylic acid monomers such as acids; partial ester monomers of ethylenically unsaturated polycarboxylic acids such as monobutyl fumarate, monobutyl maleate, mono-2-hydroxypropyl maleate; maleic anhydride Ethylenically unsaturated carboxylic acid monomers such as styrene sulfonic acid, allyloxybenzene sulfonic acid, methallyloxybenzene sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid , Methallylsulfonic acid, 4-sulfonic acid butyl methacrylate Monomer having a phospho groups; and the like. These monomers can be used alone or in combination of two or more.

In the binder used in the present invention, the content of the monomer unit used for containing an anionic group or a cationic group is preferably 0.5 to 5 wt. %, More preferably 1 to 4 wt. %. When there is too much content of the said monomer unit, the resistance of the electrochemical element electrode obtained will go up. Moreover, when there is too little content of the said monomer unit, the amount of aggregates in the adhesive coating liquid for collector coatings obtained will increase.

The shape of the binder used in the present invention is not particularly limited, but is preferably particulate. By being in the form of particles, the binding property is good, and it is possible to suppress deterioration of the capacity of the produced electrode and deterioration due to repeated charge and discharge. Examples of the particulate binder include those in which binder particles such as latex are dispersed in water, and powders obtained by drying such a dispersion.

Further, the average particle size of the binder in the binder aqueous dispersion is preferably 50 to 500 nm, more preferably 70 to 400 nm.

The glass transition temperature (Tg) of the binder is appropriately selected according to the purpose of use, but is preferably −40 ° C. or higher and 10 ° C. or lower, more preferably −35 ° C. or higher and 10 ° C. or lower, and further preferably −30 ° C. It is the range of 0 degreeC or more. If the Tg of the binder is too high, the tackiness of the current collector coating adhesive coating solution is lost. In addition, when the Tg of the binder is too low, the strength of the obtained electrochemical element electrode is lowered.

The solid content concentration of the binder aqueous dispersion is preferably 15 to 70 wt.% From the viewpoint of good workability in the production of the current collector coating adhesive coating liquid. %, More preferably 20 to 65 wt. %, More preferably 30 to 60 wt. %.

(Surfactant)
The adhesive coating liquid for current collector coating of the present invention may contain a 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 from the viewpoint of less adverse effect on the resulting electrochemical device, nonionic It is preferable to use a surfactant. Nonionic surfactants include polyoxyalkylene alkyl aryl ether surfactants, polyoxyalkylene alkyl ether surfactants, polyoxyalkylene fatty acid ester surfactants, sorbitan fatty acid ester surfactants, silicone surfactants, acetylenes Examples include alcohol surfactants and fluorine-containing surfactants.

Examples of the polyoxyalkylene alkyl aryl ether surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, and polyoxyethylene dodecyl phenyl ether.

Examples of the polyoxyalkylene alkyl ether surfactant include polyoxyethylene oleyl ether and polyoxyethylene lauryl ether.

Examples of the polyoxyalkylene fatty acid ester surfactant include polyoxyethylene oleate, polyoxyethylene laurate, and polyoxyethylene distearate.

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

Examples of acetylene alcohol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5- Examples thereof include dimethyl-1-hexyne-3ol.
Examples of fluorine-containing surfactants include fluorine alkyl esters.

The surfactant content in the current collector coating adhesive coating solution of the present invention is 0.1 wt. % Or more and 3 wt. %, Preferably 0.1 wt. % Or more and 1 wt. %, More preferably 0.2 wt. % Or more and 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 coating liquid for collector coating cannot be applied on a collector.

(Tacking material)
The adhesive coating liquid for current collector coating of the present invention may contain a tackiness-imparting material. As the tackiness-imparting material, polyhydric alcohol is preferably used, 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 alone or in combination of two or more. Among these, it is particularly preferable to use glycerin or propylene glycol from the viewpoints of volatility and plasticity.
The content of the tackiness-imparting material in the current collector coating adhesive coating solution of the present invention is preferably 0.5 to 10 wt. %, More preferably 1 to 5 wt. %. When the content of the tackiness-imparting material is too large, the performance of the obtained lithium ion secondary battery is deteriorated. Moreover, when there is too little content of a tackiness provision material, desired tackiness cannot be imparted.

(Adhesive coating solution for current collector coating)
The method for producing the current collector coating adhesive coating liquid of the present invention is not particularly limited, and any means may be used as long as each solid component can be dispersed in a dispersion medium. For example, a binder aqueous dispersion containing a binder, a surfactant and / or tackiness-imparting material used as needed are mixed together, and then a dispersion medium is added as necessary and water is added. May adjust the solid content concentration of the dispersion. Further, at least one of the surfactant and the tackiness-imparting material may be added to the binder aqueous dispersion containing the binder in a state where it is dissolved or dispersed in water.

The viscosity of the current collector coating adhesive coating liquid depends on the coating method, but is preferably 10 to 10,000 mPa · s, more preferably from the viewpoint of forming a uniform adhesive layer on the current collector. 20 to 5,000 mPa · s, more preferably 50 to 2,000 mPa · s.

Also, the amount of aggregate generated in the Marlon mechanical stability test of the adhesive coating liquid for current collector coating was 0.3 wt. %, 0.2 wt. %, Preferably 0.1 wt. More preferably, it is less than%. Here, the aggregate amount generated in the Marlon mechanical stability test is the ratio (wt.%) Of the aggregate amount (residue) to the solid content in the sample, and the aggregate amount was generated in the Marlon mechanical stability test. The agglomerates are collected by a 100 mesh wire net and dried. If the amount of aggregate generated in the Marlon mechanical stability test is too large, aggregates are generated during the application of the current collector coating adhesive coating solution.

The contact angle of the current collector coating adhesive coating solution with respect to the copper foil is less than 60 °, preferably less than 50 °, more preferably less than 45 °. If the contact angle is too large, the current collector coating adhesive coating solution is repelled at the time of coating, so that the coating cannot be performed.

In addition, the measurement result in the loop tack test of the adhesive coating liquid for the current collector coat should be measured by the loop tack test performed in a state where the current collector coating liquid is applied to the current collector. 0.5 N / 25 mm or more, preferably 1.0 N / 25 mm or more, more preferably 2.0 N / 25 mm or more. Here, the measurement result of the loop tack test is obtained by measuring the loop tack under an atmosphere of 25 ° C. according to FINAT-1991 FTM-9 (Quick-stick tack measurement). In addition, the polyethylene terephthalate film which apply | coated the adhesive coating liquid for collector coatings of this invention by 2 micrometers in thickness was used for the test panel in the said loop tack test.
If the measurement result in the loop tack test is too small, the adhesive force of the adhesive layer formed by the current collector coating adhesive coating solution is reduced.

(Current collector with adhesive layer)
By applying the adhesive coating liquid for current collector coating of the present invention onto 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, metal, carbon, conductive polymer, etc., and metal is preferably used. As the current collector metal, aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, other alloys and the like are usually used. Among these, it is preferable to use copper, aluminum, or an aluminum alloy in terms of conductivity and voltage resistance.

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

The method for applying the adhesive layer is not particularly limited. For example, the 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, brushing, or the like. Further, after forming an adhesive layer on the release paper, it may be transferred to a current collector.

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 drying by irradiation with (far) infrared rays or electron beams. It is done. Of these, a drying method using hot air and a drying method using irradiation with far infrared rays are preferable. The drying temperature and the drying time are preferably a temperature and a time at which the solvent in the current collector coating adhesive coating solution coated on the current collector can be completely removed. The drying temperature is usually 50 to 300 ° C., preferably 80 ° C. ~ 250 ° C. The drying time is usually 2 hours or less, preferably 5 seconds to 30 minutes. In addition, it is preferable that the adhesive bond layer formed with the adhesive agent coating liquid for collector coating of this invention has a tack | tuck, without heating after the coating to a collector.

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

The adhesive layer has a composition corresponding to the solid content composition of the adhesive coating liquid for current collector coating, and includes a binder, a surfactant used as needed, and a tackifier.

(Electrochemical element electrode)
An electrochemical element electrode can be obtained by forming an electrode active material layer on the current collector with an adhesive layer. Although the formation method of an electrode active material layer is not specifically limited, It is preferable to laminate | stack an electrode active material layer on an electrical power collector with an adhesive layer using the composite particle containing an electrode active material.

When laminating the electrode active material layer on the current collector with the adhesive layer, the composite particles may be formed into a sheet and then laminated on the current collector with the adhesive layer. A method in which the composite particles are directly pressure-molded on the current collector is preferred. As a method for pressure molding, for example, a roll type pressure molding apparatus provided with a pair of rolls is used, and a composite particle is rolled by a supply device such as a screw feeder while feeding the current collector with an adhesive layer by the roll. By supplying to the pressure forming device, roll pressure forming method for forming the electrode active material layer on the current collector with the adhesive layer, or by dispersing the composite particles on the current collector with the adhesive layer, For example, a method of adjusting the thickness with a blade or the like, and then forming with a pressurizing apparatus, a method of filling composite particles into a mold, and pressing the mold to form. Among these, the roll pressure molding method is preferable. In particular, since the composite particles of the present invention have high fluidity, they can be molded by roll press molding due to the high fluidity, thereby improving productivity.

The roll temperature at the time of roll pressing is preferably 25 to 200 ° C., more preferably from the viewpoint of ensuring sufficient adhesion between the electrode active material layer and the current collector with the adhesive layer. The temperature is 50 to 150 ° C, more preferably 80 to 120 ° C. Further, the press linear pressure between the rolls during roll pressing is preferably 10 to 1000 kN / m, more preferably 200 to 900 kN / m, from the viewpoint of improving the uniformity of the thickness of the electrode active material layer. More preferably, it is 300 to 600 kN / m. Further, the molding speed at the time of roll press molding is preferably 0.1 to 20 m / min, more preferably 4 to 10 m / min.

Further, post-pressurization may be further performed as necessary in order to eliminate variations in the thickness of the formed electrochemical element electrode and increase the density of the electrode active material layer to increase the capacity. The post-pressing method is preferably a pressing process using a roll. In the roll pressing step, two cylindrical rolls are arranged vertically in parallel with a narrow interval, each is rotated in the opposite direction, and pressure is applied by interposing an electrode therebetween. In this case, the temperature of the roll may be adjusted as necessary, such as heating or cooling.

(Composite particles)
The composite particles can be obtained by granulation using an electrode active material, a binder, and other components such as a water-soluble polymer and a conductive agent added as necessary. The production method of the composite particles is not particularly limited, and a slurry for composite particles containing other components such as an electrode active material, a binder, and a conductive agent that is added as necessary is used. Manufacture of granulation method, compression granulation method, stirring granulation method, extrusion granulation method, crushing granulation method, fluidized bed granulation method, fluidized bed multifunctional granulation method, and melt granulation method It can be obtained by the method. Among these, the spray-drying granulation method is preferable from the viewpoint that the composite particles can be produced relatively easily.

(Slurry for composite particles)
The slurry for composite particles used for the manufacture of composite particles is obtained 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)
When the electrochemical element is a lithium ion secondary battery, examples of the electrode active material (positive electrode active material) for the positive electrode of the lithium ion secondary battery include metal oxides capable of reversibly doping and dedoping lithium ions. It is done. Examples of the metal oxide include lithium cobaltate, lithium nickelate, lithium manganate, and lithium iron phosphate. In addition, the positive electrode active material illustrated above may be used independently according to a use, and may be used in mixture of multiple types.

Examples of the negative electrode active material (negative electrode active material) as the counter electrode of the lithium ion secondary battery positive electrode include low crystalline carbon (amorphous) such as graphitizable carbon, non-graphitizable carbon, and pyrolytic carbon. Carbon), graphite (natural graphite, artificial graphite), alloy materials such as tin and silicon, 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.

The shape of the electrode active material for the lithium ion secondary battery electrode is preferably a granulated particle. When the shape of the particles is granular, a higher-density electrode can be formed during electrode molding.

The volume average particle diameter of the electrode active material for the lithium ion secondary battery electrode is usually 0.1 to 100 μm, preferably 0.5 to 50 μm, more preferably 0.8 to 30 μm for both the positive electrode and the negative electrode.

(Conductive agent)
Specific examples of the conductive agent used in the present invention include conductive carbon black such as furnace black, acetylene black, and ketjen black (registered trademark of Akzo Nobel Chemicals Bethloten Fennaut Shap). Among these, acetylene black and furnace black are more preferable.
These conductive agents can be used alone or in combination of two or more.

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

(Other ingredients)
The composite particle slurry may contain other components such as a dispersant as required. 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 alone or in combination of two or more.

(Manufacture of composite particles)
The composite particles can be obtained, for example, by spray drying the slurry containing the electrode active material, the conductive agent, the binder, and other components added as necessary. Here, the composite particle includes at least an electrode active material, a conductive agent, and a binder. However, each of the composite particles does not exist as an independent particle, but is an electrode active material that is a constituent, a binder. One particle is formed by two or more components including an agent. Specifically, a plurality of (more preferably several to several tens) electrode active materials are formed by binding a plurality of individual particles of the two or more components to form secondary particles. It is preferable that the particles are bound to form particles.

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

(Electrochemical element)
Examples of usage of the electrochemical element electrode include a lithium ion secondary battery and a lithium ion capacitor using such an electrode, and a lithium ion secondary battery is preferable. For example, a lithium ion secondary battery uses an electrochemical element electrode obtained as described above as at least one of a positive electrode and a negative electrode, and further includes a separator and an electrolytic solution.

(Separator)
As the separator, for example, a polyolefin resin such as polyethylene or polypropylene, a microporous film or a nonwoven fabric containing an aromatic polyamide resin, a porous resin coat containing an inorganic ceramic powder, or the like can be used.

The thickness of the separator is preferably 0.5 to 40 μm, more preferably from the viewpoint of reducing resistance due to the separator in the lithium ion secondary battery and excellent workability when manufacturing the lithium ion secondary battery. The thickness is 1 to 30 μm, more preferably 1 to 25 μm.

(Electrolyte)
The electrolytic solution is not particularly limited. For example, a solution obtained by dissolving a lithium salt as a supporting electrolyte in a non-aqueous solvent can be used. Examples of the lithium salt include 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, (C ₂ F ₅ SO ₂ ) NLi, and other lithium salts. In particular, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li that are easily soluble in a solvent and exhibit a high degree of dissociation are preferably used. These can be used alone or in admixture of two or more. 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. If the amount of the supporting electrolyte is too small or too large, the ionic conductivity is lowered, and the charging characteristics and discharging characteristics of the battery are degraded.

The solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. Usually, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene. Alkyl carbonates such as carbonate (BC) and methyl ethyl carbonate (MEC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane; tetrahydrofuran; sulfolane and dimethyl sulfoxide Sulfur-containing compounds are used. In particular, dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, and methyl ethyl carbonate are preferable because high ion conductivity is easily obtained and the use temperature range is wide. These can be used alone or in admixture of two or more. Moreover, it is also possible to use an electrolyte containing an additive. The additive is preferably a carbonate compound such as vinylene carbonate (VC).

Other electrolytic solutions include gel polymer electrolytes in which a polymer electrolyte such as polyethylene oxide or polyacrylonitrile is impregnated with an electrolytic solution, lithium sulfide, LiI, Li ₃ N, Li ₂ SP—P ₂ S ₅ glass ceramic, etc. An inorganic solid electrolyte can be mentioned.

A lithium ion secondary battery is obtained by stacking a negative electrode and a positive electrode through a separator, winding this according to the shape of the battery, folding it into a battery container, pouring the electrolyte into the battery container and sealing it. It is done. Further, if necessary, an expanded metal, an overcurrent prevention element such as a fuse or a PTC element, a lead plate and the like can be inserted to prevent an increase in pressure inside the battery and 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 type, a square type, a flat type, and the like.

According to the adhesive coating liquid for current collector coating of the present invention, an electrochemical element electrode having good performance can be produced even during long molding.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples, and may be arbitrarily changed without departing from the gist and equivalent scope of the present invention. Can be implemented. In the following description, “%” and “parts” representing amounts are based on weight unless otherwise specified.
In Examples and Comparative Examples, peel strength and capacity maintenance rate were evaluated as follows.

<Peel strength>
Of the current collectors with adhesive layers obtained in the examples and comparative examples, a lithium ion secondary battery electrode manufactured using 50 m at the end (the end portion, the same shall apply hereinafter) (in Example 7, a negative electrode, In Examples and Comparative Examples other than the above, a positive electrode) was cut into a rectangle having a length of 100 mm and a width of 10 mm to obtain a test piece. This test piece was affixed to the cellophane tape fixed to the test stand. When sticking, the surface on the electrode active material layer side was faced down, and the surface on the electrode active material layer side and the adhesive surface of the cellophane tape were brought into contact. As the cellophane tape, one specified in JIS Z1522 was used.

Then, the stress when one end of the current collector was pulled vertically upward at a pulling speed of 50 mm / min and peeled was measured. This measurement was performed 3 times, the average value was calculated | required, and the said average value was made into peel strength. The higher the peel strength, the higher the binding force of the electrode active material layer to the current collector, that is, the higher the adhesion strength.
A: 3.0 N / m or more B: 2.0 N / m or more, less than 3.0 N / m C: 1.0 N / m or more, less than 2.0 N / m D: Less than 1.0 N / m

<Capacity maintenance rate (end 50m and first 50m)>
Of the current collectors with adhesive layers obtained in the examples and comparative examples, the lithium ion secondary batteries manufactured using the final 50 m and the initial 50 m were each subjected to a constant current constant voltage charging method of 0.5 C at 60 ° C. The battery was charged at a constant current until 4.2V, then charged at a constant voltage, and then a charge / discharge cycle test was performed to discharge to 3.0V at a constant current of 0.5C. The charge / discharge cycle test was conducted up to 100 cycles. The ratio of the discharge capacity at the 100th cycle to the initial discharge capacity was determined as the capacity retention rate. In each example and comparative example, 10 samples were produced, and the sample having the smallest capacity retention rate among the 10 samples was determined according to the following criteria. It shows that the capacity | capacitance reduction by repeated charging / discharging is so small that this value is large.
A: Capacity maintenance rate is 90% or more B: Capacity maintenance rate is 80% or more and less than 90% C: Capacity maintenance rate is 70% or more and less than 80% D: Capacity maintenance rate is 60% or more and less than 70% E: Capacity maintenance rate is less than 60%

Moreover, the Marlon mechanical stability test, the loop tack test, and the contact angle measurement were performed on the current collector coating adhesive coating solutions obtained in the examples and comparative examples as follows.

<Marlon mechanical stability test>
The pH of the adhesive coating solution for current collector coating obtained in Examples and Comparative Examples was adjusted to 8 ± 0.1, filtered through a 100 mesh wire net, and then the solid content concentration was adjusted to 30%. This was filtered through a 100 mesh wire net and then subjected to a Marlon mechanical stability test. The conditions were a rotational speed of 1000 rpm, a load of 15 kg, and 10 minutes. The adhesive coating liquid for current collector coating after the Marlon mechanical stability test is filtered through a 100 mesh wire mesh, and the aggregates collected on the wire mesh are dried and weighed to determine the aggregate generation amount. The ratio (%) with respect to the solid content weight of the tested adhesive coating liquid for current collector coating was determined.

<Loop tack test>
In accordance with FINAT-1991 FTM-9 (Quick-stick tack measurement), under the atmosphere at 25 ° C. of the current collector coated with the current collector coating adhesive coating liquid obtained in Examples and Comparative Examples The loop tack was measured and the tackiness was evaluated. The larger the value, the better the tackiness.

<Contact angle measurement>
The contact angles of the current collector coating adhesive coating solutions obtained in Examples and Comparative Examples were observed using “DMs-400” manufactured by Kyowa Interface Science Co., Ltd. Specifically, 2 μL of the current collector coating adhesive coating solution was dropped on the electrolytic surface of an electrolytic copper foil (product name “NC-WS”, thickness 20 μm, manufactured by Furukawa Electric). A droplet 1 minute after the dropping was observed from the horizontal direction using a measuring device. From the observed image, the contact angle between the electrolytic copper foil and the current collector coating adhesive coating solution was calculated by the θ / 2 method.

The adhesive coating liquid for collector coating, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery of Examples and Comparative Examples were produced as follows.

Example 1
(Manufacture of binder)
In an autoclave equipped with a stirrer, 300 parts of ion-exchanged water, 93.8 parts of n-butyl acrylate, 2 parts of acrylonitrile, 1.0 part of allyl glycine ether, 2.0 parts of itaconic acid, 1.2 parts of N-methylol acrylamide and molecular weight adjustment Add 0.05 part of t-dodecyl mercaptan as the agent and 0.3 part of potassium persulfate as the polymerization initiator, and after sufficiently stirring, polymerize by heating to 70 ° C., solid content concentration of 40% as the binder An aqueous dispersion of a particulate binder (acrylate binder) containing an acrylic polymer was obtained. The polymerization conversion rate determined from the solid content concentration was approximately 99%. The obtained particulate binder had a Tg of −20 ° C.

(Manufacture of adhesive coating liquid for current collector coating)
The binder is 40 wt. %, Dispanol TOC (manufactured by NOF Corporation), which is a nonionic surfactant, is 0.5 wt. %, Propylene glycol (hereinafter sometimes referred to as “PG”) as a tackiness-imparting material is 1 wt. A binder, a surfactant, a tackiness-imparting material, and water were mixed so as to obtain an adhesive coating solution for current collector coating. The amount of agglomerates generated in the Marlon mechanical stability test of the obtained current collector coating adhesive coating liquid was 0.05 wt. %, The contact angle to the copper foil was 30 °.

(Manufacture of composite particles)
92 parts of lithium cobaltate (LiCoO ₂ , hereinafter referred to as “LCO”) (particle diameter: 6 μm) as the positive electrode active material, 2.0 parts of the above binder in terms of solid content, and acetylene black (electric Denka Black powder product manufactured by Kagaku Kogyo Co., Ltd .: particle size 35 nm, specific surface area 68 m ^{2 /} g) 5.0 parts, 1.5% aqueous solution of carboxymethyl cellulose (DN-800H: manufactured by Daicel Chemical Industries) as a dispersant 1.0 part by volume in terms of the amount was mixed, and ion-exchanged water was further added so that the solid content concentration would be 40%, and mixed and dispersed to obtain a composite particle slurry for the positive electrode. This positive electrode composite particle slurry is spray-dried (manufactured by Okawara Chemical Co., Ltd.), is rotated at a rotational speed of 25,000 rpm, hot air temperature is 150 ° C. Spray drying granulation was performed at a temperature of 90 ° C. to obtain composite particles. The average volume particle diameter of the composite particles was 50 μm.

(Formation of adhesive layer)
Apply the current collector coating adhesive coating liquid to a 10 μm thick aluminum current collector at a molding speed of 20 m / min by a gravure coating method, and then apply a current of 1000 m to the current collector and dry at 120 ° C. for 2 minutes. A current collector with an adhesive layer in which an adhesive layer having a thickness of 1.2 μm was formed on the current collector was obtained. In the obtained current collector with an adhesive layer, the loop tack of the adhesive layer was 6 N / 25 mm.

(Manufacture of lithium ion secondary battery positive electrode)
The current collector with an adhesive layer is conveyed at a speed of 2 m / min, and is positively charged by a roll (rolling rough surface hot roll, manufactured by Hirano Giken Kogyo Co., Ltd.) roll (roll temperature 100 ° C., press linear pressure 4 kN / cm). The active material layer was formed into a sheet shape on the current collector with an adhesive layer to obtain a lithium ion secondary battery positive electrode having a thickness of 60 μm.

(Manufacture of negative electrode slurry and lithium ion secondary battery negative electrode)
Artificial graphite as the negative electrode active material (average particle size: 24.5 μm, graphite interlayer distance (interval of (002) plane by X-ray diffraction (d value): 9654 nm), 96 parts, styrene-butadiene copolymer latex ( BM-400B) in an amount of 3.0 parts in terms of solid content, and 1.5 parts of a 1.5% aqueous solution of carboxymethyl cellulose (DN-800H: manufactured by Daicel Chemical Industries) as a dispersant was mixed in an amount of 1.0 parts in terms of solid content. Further, ion exchange water was added so as to have a solid content concentration of 50%, and mixed and dispersed to obtain a negative electrode slurry, which was applied to a copper foil having a thickness of 18 μm and dried at 120 ° C. for 30 minutes. Thereafter, roll pressing was performed to obtain a negative electrode having a thickness of 50 μm.

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

(Manufacture of lithium ion secondary batteries)
An aluminum packaging exterior was prepared as the battery exterior. The lithium ion secondary battery positive electrode obtained above was cut into a 4 × 4 cm ² square and placed so that the surface on the current collector side was in contact with the aluminum packaging exterior. The square separator obtained above was disposed on the surface of the positive electrode active material layer of the lithium ion secondary battery positive electrode. Furthermore, the lithium ion secondary battery negative electrode obtained above was cut into a square of 4.2 × 4.2 cm ² and placed on the separator so that the surface on the negative electrode active material layer side faced the separator. Further, containing the vinylene carbonate 2.0%, was charged with LiPF ₆ solution having a concentration of 1.0 M. The solvent of this LiPF ₆ solution is a mixed solvent (EC / EMC = 3/7 (volume ratio)) of ethylene carbonate (EC) and ethyl methyl carbonate (EMC). Furthermore, in order to seal the opening of the aluminum packaging material, heat sealing was performed at 150 ° C. to close the aluminum exterior, and a laminate type lithium ion secondary battery (laminated cell) was manufactured.

(Example 2)
In the production of the binder, the binder was produced in the same manner as in Example 1 except that the amount of itaconic acid used was 1 part. The Tg of the particulate binder obtained in Example 2 was −20 ° C. Except for using this binder, the production of an adhesive coating solution for current collector coating, the production of a lithium ion secondary battery positive electrode, a lithium ion secondary battery negative electrode, and a lithium ion secondary battery in the same manner as in Example 1. Went.

In addition, the amount of aggregates generated in the Marlon 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 loop tack was 5 N / 25 mm.

Example 3
In the production of the current collector coating adhesive coating solution, the concentration of Dispanol TOC as the surfactant was 0.1 wt. %, The production of an adhesive coating solution for current collector coating, a lithium ion secondary battery positive electrode in the same manner as in Example 1 except that the binder, surfactant, tackiness-imparting material and water were mixed so that The negative electrode of the lithium ion secondary battery and the lithium ion secondary battery were manufactured.

In addition, the amount of agglomerates generated in the Marlon mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 3 was 0.05 wt. %, The contact angle with respect to the copper foil was 50 °, and the loop tack was 5 N / 25 mm.

Example 4
In the production of the binder, the binder was produced in the same manner as in Example 1 except that a particulate binder having a Tg of 0 ° C. was obtained. Using this binder, production of an adhesive coating solution for current collector coating, production of a lithium ion secondary battery positive electrode, a lithium ion secondary battery negative electrode, and a lithium ion secondary battery were conducted in the same manner as in Example 1. .

In addition, the amount of agglomerates generated in the Marlon mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 4 was 0.05 wt. %, The contact angle to the copper foil was 30 °, and the loop tack was 1 N / 25 mm.

(Example 5)
In the production of the current collector coating adhesive coating solution, the concentration of Dispanol TOC as the surfactant was 0.2 wt. %, The concentration of propylene glycol as a tackifier is 2 wt. % Production of an adhesive coating solution for current collector coating, lithium ion secondary battery positive electrode in the same manner as in Example 4 except that the binder, surfactant, tackiness-imparting material and water were mixed so that The negative electrode of the lithium ion secondary battery and the lithium ion secondary battery were manufactured.

In addition, the amount of agglomerates generated in the Marlon mechanical stability test of the adhesive coating liquid for current collector coating obtained in Example 5 was 0.05 wt. %, The contact angle with respect to the copper foil was 30 °, and the loop tack was 6 N / 25 mm.

(Example 6)
In the production of the adhesive coating liquid for current collector coating, glycerin was used as the tackifier and the concentration of Dispanol TOC as the surfactant was 0.8 wt. %, The concentration of glycerin as a tackifier is 1 wt. %, The production of an adhesive coating solution for current collector coating, a lithium ion secondary battery positive electrode in the same manner as in Example 1 except that the binder, surfactant, tackiness-imparting material and water were mixed so that The negative electrode of the lithium ion secondary battery and the lithium ion secondary battery were manufactured.

In addition, the amount of agglomerates generated in the Marlon 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 loop tack was 5 N / 25 mm.

(Example 7)
(Manufacture of adhesive coating liquid for current collector coating)
In the production of the current collector coating adhesive coating liquid, instead of the above binder as a binder, styrene-butadiene copolymer latex (BM-400B) (hereinafter referred to as “SBR binder”) may be used. ) And Dispanol TOC as a surfactant is 0.8 wt. %, Propylene glycol is 1 wt. A binder, a surfactant, a tackiness-imparting material, and water were mixed so as to obtain an adhesive coating solution for current collector coating.

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

(Manufacture of composite particles)
Artificial graphite as the negative electrode active material (average particle size: 24.5 μm, graphite interlayer distance (interval of (002) plane by X-ray diffraction (d value): 92 parts): 92 parts, styrene-butadiene copolymer latex described above (BM-400B) was mixed with 2.0 parts in terms of solid content, and 1.5 parts of a carboxymethylcellulose 1.5% aqueous solution (DN-800H: manufactured by Daicel Chemical Industries, Ltd.) as a dispersant was mixed with 1.0 part in terms of solid content. Further, ion-exchanged water was added so as to have a solid content concentration of 40%, and mixed and dispersed to obtain a composite particle slurry for a negative electrode, which was then spray-dried (Okawara Chemical Co., Ltd.). Made by using a rotating disk type atomizer (diameter 65 mm), rotating at 25,000 rpm, hot air temperature 150 ° C., and particle recovery outlet temperature 90 ° C. To obtain a composite particle. The average volume particle size of the composite particles was 50 [mu] m.

(Production of positive electrode slurry and lithium ion secondary battery positive electrode)
92 parts of LiCoO ₂ (hereinafter sometimes abbreviated as “LCO”) as the positive electrode active material and polyvinylidene fluoride (PVDF; “KF-1100” manufactured by Kureha Chemical Co., Ltd.) as the positive electrode binder have a solid content. Add 6 parts of acetylene black (“HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd.) and 20 parts of N-methylpyrrolidone and mix with a planetary mixer to obtain a slurry for positive electrode. It was. This positive electrode slurry was applied to an aluminum foil having a thickness of 18 μm, dried at 120 ° C. for 30 minutes, and then roll pressed to obtain a lithium ion secondary battery positive electrode having a thickness of 60 μm.

(Manufacture of lithium ion secondary batteries)
A separator similar to that in Example 1 was prepared, and the lithium ion secondary battery negative electrode and lithium ion secondary battery positive electrode obtained in Example 7 were used in the same procedure as in Example 1 to form a laminated lithium ion secondary battery. A battery (laminated cell) was produced.

(Example 8)
In the production of the current collector coating adhesive coating solution, in place of the above binder as a binder, polyethylene oxide was used, except that the binder, surfactant, tackifier, and water were mixed. In the same manner as in Example 1, production of an adhesive coating solution for current collector coating, production of a lithium ion secondary battery positive electrode, a lithium ion secondary battery negative electrode, and a lithium ion secondary battery were carried out.

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

(Comparative Example 1)
In the production of the binder, the binder was produced in the same manner as in Example 1 except that itaconic acid was not used. The Tg of the particulate binder obtained in Comparative Example 1 was −20 ° C. In addition, in the production of the current collector coating adhesive coating solution, the current collector coat adhesive coating solution was produced without using the tackifier. Moreover, the lithium ion secondary battery positive electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery were the same as in Example 1 except that the adhesive coating liquid for collector coating obtained in Comparative Example 1 was used. Was manufactured.

The amount of aggregate generated in the Marlon 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 loop tack was 4 N / 25 mm.

(Comparative Example 2)
Adhesive for current collector coating in the same manner as in Example 1 except that in the production of the adhesive coating liquid for current collector coating, a binder, a tackifier and water were mixed without using a surfactant. Production of the agent coating liquid, lithium ion secondary battery positive electrode, lithium ion secondary battery negative electrode and lithium ion secondary battery were carried out.

In addition, the amount of agglomerates generated in the Marlon mechanical stability test of the adhesive coating liquid for current collector coating obtained in Comparative Example 2 was 0.1 wt. %, The contact angle with respect to the copper foil was 60 °, and the loop tack was 4 N / 25 mm.

(Comparative Example 3)
In the production of the binder, the binder was produced in the same manner as in Example 1 except that a particulate binder having a Tg of 10 ° C. was obtained. Further, using this binder, Dispanol TOC as a surfactant was 0.05 wt. %, Propylene glycol is 1 wt. The adhesive coating liquid for current collector coating was produced by mixing the binder, surfactant, tackiness-imparting material, and water so as to be in a percentage. A lithium ion secondary battery positive electrode, a lithium ion secondary battery negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1 except that this current collector coating adhesive coating solution was used.

The amount of aggregate generated in the Marlon mechanical stability test of the adhesive coating liquid for current collector coating obtained in Comparative Example 3 was 0.1 wt. %, The contact angle with respect to the copper foil was 80 °, and the loop tack was 0.1 N / 25 mm.

As shown in Table 1, an adhesive coating liquid for a current collector coating containing a binder and water, and the amount of aggregate generated in the Marlon mechanical stability test of the coating liquid is a solid content In contrast, 0.3 wt. Lithium ion secondary using a current collector coating adhesive coating solution having a contact angle to the copper foil of less than 60 ° and less than 60 °, and a measurement result of the loop tack test of 0.5 N / 25 mm or more. The peel strength of the battery electrode is good, and the capacity retention rate of the lithium ion secondary battery including the lithium ion secondary battery electrode using the current collector coating adhesive coating solution is good at both the initial 50 m and the final 50 m. there were.

Claims

An adhesive coating liquid for a current collector coat containing a binder and water,
The amount of agglomerates generated in the Marlon mechanical stability test of the coating liquid was 0.3 wt. %, And
The contact angle to the copper foil is less than 60 °,
An adhesive coating solution for current collector coating, wherein the measurement result in the loop tack test is 0.5 N / 25 mm or more.
The adhesive coating liquid for current collector coating according to claim 1, wherein the binder is a particulate binder.
3. The adhesive coating liquid for current collector coating according to claim 2, wherein the particulate binder has a glass transition temperature of −40 ° C. or higher and 10 ° C. or lower.
A surfactant, and the concentration of the surfactant is 0.1 wt. % Or more and 3 wt. The adhesive coating solution for a current collector coating according to any one of claims 1 to 3, wherein the adhesive coating solution is less than%.
The adhesive coating liquid for a current collector coating according to any one of claims 1 to 4, comprising a tackiness-imparting material.