KR20160146737A - Production method for complex particles for use in electrode of electrochemical element - Google Patents

Abstract

A method of producing a composite particle for an electrochemical device electrode, comprising the steps of: preparing a slurry for dispersing or dissolving an electrode active material and a binder in a medium to obtain a slurry (4); an assembling step for spraying and drying the slurry to obtain the granulated particles And removing the foreign particles and / or coarse particles from the granulated particles, wherein the solid concentration of the slurry obtained in the slurry producing step is 20 wt% or more and 90 wt% or less, and spray drying The flow rate of dry air at the city is more than 10 m / s and less than 40 m / s.

Description

TECHNICAL FIELD [0001] The present invention relates to a composite particle for an electrochemical device electrode,

The present invention relates to a method for producing composite particles for electrochemical device electrodes.

BACKGROUND ART [0002] Electrochemical devices such as lithium ion secondary batteries, which are small in size, light in weight, have high energy density, and can be repeatedly charged and discharged, are rapidly expanding in demand. BACKGROUND ART [0002] Lithium ion secondary batteries are used in fields such as portable telephones, notebook personal computers, and electric vehicles because of their relatively large energy densities.

These electrochemical devices are required to be further improved, such as lowering the resistance, increasing the capacity, and improving the mechanical characteristics and productivity, in accordance with the expansion and development of applications. In such a situation, an electrode for an electrochemical device is required to have a more highly productive manufacturing method, and various improvements have been made to a material for an electrode for an electrochemical device that is suitable for a high-speed forming method and a manufacturing method thereof .

An electrode for an electrochemical device is generally formed by laminating an electrode active material layer and an electrode active material layer formed by binding a conductive material, which is used if necessary, with a binder on a current collector. The electrode for an electrochemical device has been produced by applying a slurry composition containing an electrode active material, a binder, a conductive material, etc. to a current collector and removing the solvent by heat or the like. However, It has been difficult to produce a uniform electrochemical device. Further, this method has a problem that the working environment is deteriorated due to high cost, and the manufacturing apparatus becomes large.

On the contrary, it has been proposed to obtain a uniform electrochemical device by obtaining composite particles and powder-molding them. As such a method for producing composite particles for electrochemical device electrodes, for example, Patent Document 1 discloses a method for manufacturing a composite particle comprising a step of spray drying and granulating a slurry composed of an electrode active material, a conductive material, a dispersion type binder and a dissolution type resin Method is disclosed. However, mass production of composite particles for electrochemical device electrodes has not been considered. (Dry formability) of the obtained composite particles and the characteristics (cycle characteristics) of the battery using the molded electrode were lowered when the scaling-up of the single layer by mass production was examined. In addition, And that the cause is due to the broadening of the particle size distribution during the assembly process of the composite particles.

Japanese Laid-Open Patent Publication No. 2006-303395

An object of the present invention is to provide a method for producing composite particles for an electrochemical device electrode which can suppress the broadening of the particle size distribution even in the case of mass production.

Means for Solving the Problems As a result of intensive investigations in order to solve the above problems, the present inventors have found that a slurry prepared at a predetermined concentration including an electrode active material and a binder is used, and in the process of assembling composite particles, To achieve the above-described object, thereby completing the present invention.

That is, according to the present invention,

(1) A method for producing composite particles for an electrochemical device electrode, comprising the steps of: preparing a slurry for dispersing or dissolving an electrode active material and a binder in a medium to obtain a slurry; spraying and drying the slurry to obtain granulated particles; And a removal step of removing foreign matter and / or coarse particles from the particles, wherein the solid content concentration of the slurry obtained in the slurry production step is 20 wt% or more and 90 wt% or less, A method for producing composite particles for electrochemical device electrodes having a flow rate of air of 10 m / s or more and less than 40 m / s,

(2) The electrochemical method as described in (1), wherein the granular particles are conveyed by air after the granulating process, wherein the air flow rate in the conveying step is not less than 0.5 m / s and not more than 20 m / A method for producing composite particles for device electrodes,

(3) The meat produced by dividing the mass flow rate (kg / h) of the granulated particles per unit time by the mass flow rate (kg / h) of the air consumed for transporting the granulated particles per unit time in the above- (2), wherein the ratio (solid ratio) of the composite particles for the electrochemical device electrode is 5 or more and 150 or less.

According to the present invention, it is possible to provide a method for producing composite particles for electrochemical device electrodes, which can suppress the broadening of the particle size distribution even in mass production.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a composite particle production apparatus used in a method for producing composite particles for an electrochemical device electrode according to an embodiment of the present invention. FIG.

Hereinafter, a method for producing composite particles for an electrochemical device electrode (hereinafter sometimes simply referred to as " composite particles ") according to an embodiment of the present invention will be described with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a composite particle production apparatus used in a method for producing composite particles for an electrochemical device electrode according to an embodiment of the present invention. FIG.

As shown in Fig. 1, the composite particle production apparatus 2 includes a slurry tank 6 for producing a slurry 4 by stirring a raw material introduced through a raw material inlet pipe 8 with a stirring blade 10, a slurry 4), a pipe 20 for transferring the granulated particles 12 produced by the granulating device 14, granulated particles (for example, (22) for removing foreign matter and / or coarse particles from the electrochemical device electrode composite particles (12), and a storage tank (24) for storing the electrochemical device electrode composite particles (26).

Here, the assembling device 14 is provided with a drying furnace 16, and a rotary disk 18 for spraying the slurry 4 while rotating is provided in the drying furnace 16. An air inlet 17a is provided in the upper portion of the drying furnace 16 and a connection portion (not shown) in the lower portion of the drying furnace 16 is provided to the pipe 20. The cyclones 30 and 34 are provided with two cyclones 30 and 34 for separating the granulated particles 12 and the air and allowing a part of the air to flow out. 30a, and 34a, respectively. On the downstream side of the cyclone 30, a recovery tank 32 is provided, and pressurized air is supplied to the recovery tank 32. Further, air is introduced into the pipe 20 on the downstream side of the recovery tank 32 from the air inlet 17b.

Next, a method for producing composite particles for an electrochemical device electrode using the composite particle production apparatus 2 will be described.

(Slurry production process)

In the slurry producing process of the present invention, the electrode active material and the binder are dispersed or dissolved in the medium to obtain a slurry.

The slurry production process is carried out in the slurry tank 6 of the composite particle production apparatus 2 shown in Fig. 1 and the slurry 4 is fed into the slurry tank 6 with a raw material containing an electrode active material, a binder and a medium , And stirring with a stirring blade (10).

Here, the slurry 4 can be obtained by dispersing or dissolving the electrode active material and the binder in the medium. The slurry 4 may contain a viscosity adjusting agent and carbon fine particles as required.

On the other hand, in place of the stirring using the stirring vane 10 in the slurry tank 6, mixing by stirring, shaking, rotating, or the like may be performed. Further, a dispersion kneading apparatus such as a homogenizer, a ball mill, a sand mill, a roll mill, a planetary mixer and a planetary kneader may be used.

The method of dispersing or dissolving the electrode active material, the binder, and optionally the viscosity adjuster or carbon fine particles in the medium is not particularly limited. For example, the medium may contain an electrode active material, a binder and a viscosity adjuster Adding carbon microparticles and mixing them; A method in which a viscosity adjusting agent is dissolved in a medium, a binder dispersed in the medium is added and mixed, and finally, an electrode active material and carbon fine particles are added and mixed; A method in which an electrode active material and carbon fine particles are added to a binder dispersed in a medium and mixed, and a viscosity adjusting agent dissolved in the medium is added to the mixture and mixed; A method of mixing an electrode active material and carbon fine particles to be used according to need into a powder, then adding a proper amount of a viscosity adjusting agent and a medium, kneading and dispersing the mixture, and then adding a medium and a binder for viscosity adjustment; A method in which an electrode active material and carbon fine particles to be used are added and dispersed in a medium on which a viscosity adjusting agent is dissolved and then a binder is added; And the like.

The viscosity of the slurry obtained by the slurry production process is preferably 100 to 5000 mPa · s, more preferably 100 to 3000 mPa · s, and still more preferably 100 to 2000 mPa · s. On the other hand, the viscosity of the slurry was measured using a B-type viscometer at a temperature of 25 ° C and a rotation speed of 60 rpm.

The solid content of the slurry obtained by the slurry production process is 20 wt% or more and 90 wt% or less, preferably 30 wt% or more and 90 wt% or less, and more preferably 35 wt% or more and 90 wt%. If the solid content of the slurry is too high, the viscosity range can not be set, and the fluidity also deteriorates. If the solid content of the slurry is too low, the productivity of the composite particles deteriorates. Further, the stability of the slurry deteriorates.

(Electrode active material)

The electrode active material used in the present invention is appropriately selected depending on the kind of the electrochemical device to be produced. For example, when the electrochemical device to be produced is a lithium ion secondary battery, the positive electrode active material used for the positive electrode of the lithium ion secondary battery includes a metal oxide capable of reversibly doping and dedoping lithium ions. Examples of such metal oxides include lithium cobalt oxide (hereinafter sometimes referred to as " LCO "), lithium nickel oxide, lithium manganese oxide, lithium iron phosphate (hereinafter sometimes referred to as & Lithium manganese phosphate, lithium manganese phosphate, lithium vanadium phosphate, lithium vanadate, lithium nickel-manganese-cobaltate (hereinafter may be referred to as "NMC"), lithium nickel-cobaltate, lithium nickel- , Iron-manganese-cobalt oxide, lithium iron silicate, lithium iron-manganese lithium, vanadium oxide, copper vanadate, niobium oxide, titanium sulfide, molybdenum oxide and molybdenum sulfide. On the other hand, the positive electrode active materials exemplified above may be suitably used singly or as a mixture of plural kinds thereof. Lithium iron phosphate or lithium manganese phosphate may also be used. Further, polymers such as polyacetylene, poly-p-phenylene, and polyquinone can be mentioned. Of these, it is preferable to use LCO, NMC, and LFP.

Herein, in the present invention, dopamine refers to the phenomenon of insertion of lithium ions and / or anions into the positive electrode or insertion of lithium ions into the negative electrode. In addition, deodorization also means release, desorption, and desorption, and defines the opposite phenomenon of the dope.

Examples of the negative electrode active material used for the negative electrode of the lithium ion secondary battery as the negative electrode of the positive electrode of the above lithium ion secondary battery include easily graphitizable carbon, hard graphitizable carbon, activated carbon, pyrolytic carbon, and the like Carbon materials such as low-crystalline carbon (amorphous carbon), graphite (natural graphite, artificial graphite), carbon nanowalls, carbon nanotubes, carbon materials having different physical properties, alloy materials such as tin and silicon, Oxides such as tin oxide, vanadium oxide and lithium titanate, and polyacene. Of these, graphite and activated carbon are preferably used. On the other hand, the electrode active materials exemplified above may be suitably used singly or in a mixture of plural kinds thereof.

(bookbinder)

The binder used in the present invention is not particularly limited as long as it is a compound capable of bonding the above-mentioned electrode active material to each other, but in the present invention, a dispersion type binder having a property of being dispersed in a medium is preferable. Examples of the dispersible binder include a polymer such as a silicone polymer, a fluorine-containing polymer, a conjugated diene polymer, an acrylate polymer, polyimide, polyamide and polyurethane. Among these, Based polymer and an acrylate-based polymer are preferable.

The conjugated diene polymer is a copolymer obtained by polymerizing a homopolymer of a conjugated diene or a monomer mixture containing a conjugated diene, or a hydrogenated product thereof. The proportion of the conjugated diene in the monomer mixture is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more. Specific examples of the conjugated diene polymer include conjugated diene homopolymers such as polybutadiene and polyisoprene; Aromatic vinyl-conjugated diene copolymers such as styrene-butadiene copolymer (SBR) which may be carboxy-modified; Vinyl cyanide-conjugated diene copolymers such as acrylonitrile-butadiene copolymer (NBR); Hydrogenated SBR, and hydrogenated NBR. Of these, SBR, NBR and hydrogenated NBR are preferable.

The acrylate-based polymer is a polymer containing a (meth) acrylic acid ester monomer unit. Among them, a polymer containing at least one of an?,? -Unsaturated nitrile monomer unit and an acidic functional group-containing monomer unit including a (meth) acrylic acid ester monomer unit is preferable, and an?,? - unsaturated nitrile monomer unit and an acid A polymer containing both functional group-containing monomer units is more preferable. By using an acrylate-based polymer containing the monomer unit, the binding force of the binder can be further improved. On the other hand, in the present specification, " including a monomer unit " means that " a polymer obtained by using the monomer contains a structural unit derived from a monomer ".

Examples of the (meth) acrylic acid ester monomer that can be used in the production of the acrylate-based polymer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, Acrylic acid such as acrylic acid, methacrylic acid and the like, such as acrylic acid, methacrylic acid, maleic acid, maleic acid, maleic acid, Alkyl esters; And examples thereof include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, Methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, n-butyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, Esters and the like. Among them, when used as a lithium ion secondary battery as an electrode, it is preferable to use a non-carbonyl oxygen atom bonded to a non-carbonyl oxygen atom from the viewpoint of exhibiting good ionic conductivity and prolonging the battery life by being adequately swollen in an electrolytic solution, The alkyl group having 4 to 13 carbon atoms is preferable, and n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. On the other hand, they may be used alone or in combination of two or more.

The content of the (meth) acrylic acid ester monomer unit in the acrylate-based polymer is preferably 50% by weight or more, more preferably 60% by weight or more, and preferably 95% by weight or less, 90% by weight or less. When the content of the monomer unit derived from the (meth) acrylic acid ester monomer is 50% by weight or more, the flexibility of the binder can be increased and the electrode can be prevented from being broken easily. When the content is 95% by weight or less, the mechanical strength and bondability of the binder can be improved.

As the?,? - unsaturated nitrile monomer, for example, acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is particularly preferable for improving mechanical strength and adhesion. On the other hand, they may be used alone or in combination of two or more.

The content of the?,? - unsaturated nitrile monomer units in the acrylate polymer is preferably 3% by weight or more, more preferably 5% by weight or more, preferably 40% by weight or less, Is not more than 30% by weight. By setting the content of the?,? - unsaturated nitrile monomer units to 3 wt% or more, the mechanical strength of the binder can be improved and the adhesion between the electrode active material and the collector or between the electrode active materials can be increased. When the content is 40% by weight or less, the flexibility of the binder can be increased, and the electrode can be prevented from being broken easily.

Examples of the acidic functional group-containing monomer that can be used in the production of the acrylate-based polymer include a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, and a monomer having a phosphoric acid group.

Examples of the monomer having a carboxylic acid group include a monocarboxylic acid and a derivative thereof, a dicarboxylic acid, an acid anhydride thereof, and derivatives thereof. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid and crotonic acid. Examples of the derivative of the monocarboxylic acid include 2-ethylacrylic acid, isocrotonic acid,? -Acetoxyacrylic acid,? -Trans-aryloxyacrylic acid,? -Chloro-? -Emethoxyacrylic acid,? -Diaminoacrylic acid . Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, and the like. Examples of the acid anhydrides of dicarboxylic acids include maleic anhydride, acrylic acid anhydride, methyl maleic anhydride, and dimethyl maleic anhydride. Examples of derivatives of dicarboxylic acids include methyl allyl maleate such as methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloromaleic acid, dichloromaleic acid, and fluoromaleic acid, maleic acid diphenyl maleate, Decyl, maleododecyl, octadecyl maleate, and maleic acid esters such as maleic acid fluoroalkyl.

Examples of the monomer having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth) allylsulfonic acid, styrenesulfonic acid, ethyl (meth) acrylate-2-sulfonate, 2-hydroxypropanesulfonic acid, and the like. Meanwhile, in the present specification, the term "(meth) allyl" means allyl and / or methallyl.

Examples of the monomer having a phosphoric acid group include ethyl 2 - ((meth) acryloyloxy) ethyl phosphate, methyl 2- (meth) acryloyloxyethyl phosphate and ethyl (meth) acryloyloxyethyl phosphate. have.

Of these, examples of the acidic functional group-containing monomer include acrylic acid, methacrylic acid, methyl methacrylate, itaconic acid, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), 2- ((meth) acryloyloxy ) Ethyl is preferred. Further, acrylic acid, methacrylic acid and itaconic acid are preferable, and itaconic acid is particularly preferable from the viewpoint of enhancing the storage stability of the acrylate-based polymer. On the other hand, they may be used alone or in combination of two or more.

The content of the acidic functional group-containing monomer units in the acrylate-based polymer is preferably 0.5% by weight or more, more preferably 1% by weight or more, particularly preferably 1.5% by weight or more, % Or less, more preferably 4 wt% or less. When the content of the acidic functional group-containing monomer units is 0.5% by weight or more, the binder property as a binder is enhanced and the cycle characteristics of the lithium ion secondary battery can be improved. When the amount is 5% by weight or less, the production stability and storage stability of the acrylate-based polymer can be improved.

Here, the acrylate-based polymer may contain a crosslinkable monomer unit in addition to the above-mentioned monomer unit. Examples of the crosslinkable monomer include monomers containing an epoxy group, monomers containing a carbon-carbon double bond and an epoxy group, monomers containing a halogen atom and an epoxy group, monomers containing an N-methylolamide group, oxetanyl A monomer containing an oxazoline group, and a multifunctional monomer having at least two olefinic double bonds.

The content of the crosslinkable monomer unit in the acrylate polymer used as the binder is such that the acrylate polymer exhibits a suitable swelling property with respect to the electrolytic solution and can further improve the rate characteristics and cycle characteristics of the lithium ion secondary battery , It is preferably not less than 0.01% by weight, more preferably not less than 0.05% by weight, preferably not more than 0.5% by weight, more preferably not more than 0.3% by weight.

In addition, the acrylate-based polymer may contain monomer units derived from monomers other than those described above. Examples of such a monomer unit include a polymerization unit derived from a vinyl monomer and a monomer unit containing a hydroxyl group. Examples of vinyl monomers include carboxylic acid esters having two or more carbon-carbon double bonds such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; Halogen-containing monomers such as vinyl chloride and vinylidene chloride; Vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate; 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; Containing vinyl compounds such as N-vinylpyrrolidone, vinylpyridine and vinylimidazole. Examples of the hydroxyl group-containing monomer include ethylenically unsaturated alcohols such as (meth) allyl alcohol, 3-buten-1-ol and 5-hexen-1-ol, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di- unsaturated carboxylic acid alkanolamine esters represented by the general formula ^{_{CH 2 = CR 1 (C n}} H 2n -1 O) -COO- m -H (m is an integer of from 2 to 9, n is an integer of 2-4, R ¹ is hydrogen or represents a methyl group) which is a polyalkylene glycol with (meth) acrylic acid and esters, 2-hydroxyethyl-2 'represented by (meth) acryloyloxyethyl phthalate, 2-hydroxyethyl - Mono (meth) acrylate esters of dihydroxy esters of dicarboxylic acids such as 2 '- (meth) acryloyloxy succinate, 2-hydroxyethyl vinyl esters (Meth) allyl-2-hydroxypropyl ether, (meth) allyl-2-hydroxypropyl ether, Hydroxybutyl ether, (meth) allyl-2-hydroxybutyl ether, (meth) allyl-3-hydroxybutyl ether, Polyoxyalkylene glycol (meth) monoallyl ethers such as mono (meth) allyl ethers of alkylene glycol, diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether, glycerin mono Halogen and hydroxy substituents of (poly) alkylene glycols, such as allyl ether, (meth) allyl-2-chloro-3-hydroxypropyl ether, (meth) allyl- Of monohydric alcohols such as mono (meth) allyl ether, eugenol, isougenol and the like (Meth) allyl thioethers of alkylene glycol such as mono (meth) allyl ether and its halogen substituents, (meth) allyl-2-hydroxyethylthioether and (meth) allyl- . On the other hand, they may be used alone or in combination of two or more.

Here, the method of producing the binder such as the acrylate-based polymer described above is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method may be used. Among these, an emulsion polymerization method using an emulsifier is preferable. On the other hand, when the binder is produced by the emulsion polymerization method, it is preferable to use at least a polyoxyethylene surfactant as the surfactant to be added as the emulsifier used in the polymerization. As the polymerization method, addition polymerization such as ion polymerization, radical polymerization or living radical polymerization can be used. As the polymerization initiator, a known polymerization initiator, for example, those described in JP-A-2012-184201, may be used.

The binder of the dispersion type used in the present invention preferably has a granular shape. The particles are stable, and the binding property is good, and deterioration due to repetition of charging and discharging can be suppressed in the capacity of the produced electrode. The binder includes, for example, a state in which a binder such as a latex is dispersed in water, and a binder obtained by drying such a dispersion.

The volume average particle diameter of the binder of the dispersed type used in the present invention is preferably 0.001 to 100 占 퐉, more preferably 10 to 1000 nm, and still more preferably 10 占 퐉 to 1000 nm, from the viewpoint of the strength and flexibility of the electrode for electrochemical device obtained. Is 50 to 500 nm.

The amount of the binder to be used is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the electrode active material in terms of solid content, from the viewpoint of good electrode formability and good electrochemical device performance. 8 parts by weight, more preferably 0.5 to 5 parts by weight.

(Viscosity adjusting agent)

The slurry obtained in the slurry producing step of the present invention may contain a viscosity adjusting agent as required. Examples of the viscosity adjusting agent include cellulose derivatives such as carboxymethyl cellulose (hereinafter sometimes referred to as " CMC "); Poly (meth) acrylates such as poly (meth) acrylate; Polyvinyl alcohol, modified polyvinyl alcohol, polyethylene oxide; Polyvinyl pyrrolidone, polycarboxylic acid, starch oxide, starch phosphate, casein, various modified starches, chitin, and chitosan derivatives. Of these, CMC is preferable. The viscosity adjuster is preferably used in an amount of 0.5 to 2 parts by weight, more preferably 0.7 to 1.5 parts by weight, based on 100 parts by weight of the electrode active material.

(Carbon fine particles)

The slurry obtained in the slurry producing step of the present invention may contain carbon fine particles as necessary.

As the carbon fine particles, conductive carbon such as furnace black, acetylene black, and Ketjen black (registered trademark of Akzo Nobel Chemicals Co., Ltd.), carbon nanotube, carbon nanohorn, and graphene are preferably used. Of these, acetylene black is more preferable. The average particle diameter of the carbon fine particles is not particularly limited, but is preferably smaller than the average particle size of the electrode active material, preferably 0.001 to 10 탆, more preferably 0.005 to 5 탆, from the viewpoint of exhibiting sufficient conductivity with a smaller usage amount. μm, more preferably 0.01 to 1 μm.

The amount of the carbon fine particles to be used in the case of adding carbon fine particles is preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the electrode active material. If the amount of the carbon fine particles used is too large, it becomes difficult to prepare a slurry. If the amount of the carbon fine particles used is too small, the resistance of the obtained electrochemical device may increase.

(media)

As the medium used for the slurry of the present invention, it is preferable to use water. On the other hand, in the present invention, as long as the dispersion stability of the slurry is not deteriorated, a medium in which a hydrophilic solvent is mixed with water may be used. Examples of the hydrophilic solvent include methanol, ethanol, N-methylpyrrolidone and the like, and it is preferably 5% by weight or less with respect to water.

(Assembly process)

In the granulation process of the present invention, granulated granules are obtained by spray drying the slurry obtained in the slurry production process. The assembling process can be carried out, for example, by using the assembling device 14 of the composite particle production apparatus 2 shown in Fig. That is, the slurry 4 obtained in the slurry production step is sprayed while rotating the rotary disk 18 provided in the drying furnace 16 to obtain the granulated particles 12. Here, in the granulated particles 12, the electrode active material and the binder are not individually present as independent particles, but are formed by two or more components including an electrode active material and a binder as constituent components (one particle) will be. Specifically, a plurality of individual particles of two or more components are combined to form secondary particles, and a plurality (preferably several to several tens) of electrode active materials are bound by a binder to form particles .

Further, the shape of the granulated particles is preferably substantially spherical in terms of fluidity. That is, when the minor axis of the assembled particle is L _s , the major axis is L _l , L _a = (L _s + L ₁ ) / 2, and (1 - (L ₁ - L _s ) / L _a ) × 100 is a sphericity (%), the sphericity is preferably 80% or more, more preferably 90% or more. Here, the short axis L _s and the long axis L _l are values measured from a scanning electron microscopic photograph image.

The volume average particle size of the granulated particles is preferably 10 to 200 占 퐉, more preferably 20 to 180 占 퐉, and still more preferably 30 to 170 占 퐉. The average particle size of the granulated particles is a volume average particle size calculated by a laser diffraction particle size distribution measuring apparatus (for example, Microtrack; manufactured by Nikkiso Co., Ltd.).

Spray drying is a method in which a slurry is sprayed in dry air to dry. As an apparatus for spraying the slurry, an atomizer can be mentioned. In the case of using an agitator of the rotary disc type, the slurry is introduced into the approximate center of the disc rotating at a high speed, and the slurry is discharged out of the disc by the centrifugal force of the disc. In the rotary disc method, the rotation speed of the disc depends on the size of the disc, preferably 5,000 to 30,000 rpm, more preferably 15,000 to 30,000 rpm. The lower the rotational speed of the disk, the larger the spray droplet size and the larger the average particle size of the resulting composite particles.

The temperature of the slurry to be sprayed is preferably room temperature, but it may be heated to a temperature higher than room temperature. The temperature of the drying air at spray drying is preferably 25 to 250 ° C, more preferably 50 to 200 ° C, and still more preferably 80 to 200 ° C.

Here, the flow velocity of the dry air is preferably 10 m / s or more and less than 40 m / s, preferably 10 m / s or more and 35 m / s or less, more preferably 10 m / Is not less than 10 m / s and not more than 25 m / s. If the flow rate of dry air is too fast, the assembled granules are destroyed. If the flow velocity of the dry air is too low, the productivity of the granulated particles is lowered. On the other hand, the flow rate of the dry air is controlled by the cyclone differential pressure (the air inlet 17a of the drying furnace 16 and the cyclone 30 located on the drying furnace 16 side among the two cyclones installed in the middle of the pipe 20) The pressure difference of the air outlet 30a).

(Transferring process)

The composite particle for electrochemical device electrode of the present invention may include a transferring step. In the transferring process, the assembled particles produced in the assembling process are transferred by air in the pipe 20. Here, in the transferring step, it is preferable to carry out transfer by flowing air through the pipe 20. Further, in the transferring step, it is preferable to transfer at a low speed and at a high density. Specifically, in order to transfer the granulated particles at a low speed and at a high density by the flowing air through the pipe 20, specifically, the granulated particles separated from the air in the cyclone 30 located at the side of the drying furnace 16 are collected Is once recovered by the tank 32, and is conveyed by being pressed under the high density state.

The flow velocity of the flowing air at the time of conveyance is determined by the amount of air flowing from the air inlet 17b of the pipe 20 shown in Fig. 1 and the amount of air flowing into the cyclone 34 located further away from the drying furnace 16 Preferably not less than 0.5 m / s and not more than 20 m / s, more preferably not less than 1 m / s and not more than 20 m / s, and more preferably not more than 20 m / Is not less than 1 m / s and not more than 15 m / s, particularly preferably not less than 1 m / s and not more than 8 m / s. If the flow velocity of the flowing air at the time of transportation is too fast, the granulated particles may be destroyed. Further, if the flow velocity of the flowing air at the time of conveyance is too slow, the productivity of the granulated particles deteriorates.

The density in the feeding step can be defined by the meat ratio at the time of feeding. The meat ratio at the time of feeding is preferably 5 to 150, more preferably 10 to 150. Here, meat is calculated by dividing the mass flow rate (kg / h) of the granulated particles per unit time by the mass flow rate (kg / h) of the air consumed for transporting the granulated particles per unit time. If the value of the meat ratio is large, it is possible to transfer a large number of granulated particles with a small amount of air, and the efficiency is good. If the meat ratio is too small, the granulated particles may be destroyed during transportation.

(Removal process)

In the removing step of the present invention, foreign matters and / or coarse particles are removed from the assembled particles obtained in the assembling step or the assembled particles transferred in the transferring step. The method for removing foreign matter and / or coarse particles from the assembled particles is not particularly limited, but it is preferable to remove the foreign matter and / or coarse particles with the body 22 (see FIG. 1). By removing foreign matters and / or coarse particles from the assembled particles, the composite particles for electrochemical device electrode 26 can be obtained.

Herein, in the present invention, a foreign matter means impurities originally mixed in an electrode active material, a binder, etc., as a raw material of the granulated particles, or a part of the pipe (an inner wall of a pipe or a joint portion) And the like.

Here, in the present invention, coarse particles preferably have a volume average particle diameter of not less than 5 times, more preferably not less than 4 times, and more preferably not less than 3 times the volume average particle diameter of the obtained composite particles.

The opening diameter of the sieve 22 used for separating foreign matters and / or coarse particles by the sieve 22 is preferably 1.1 to 6.0 times, more preferably 1.1 To 5.0 times, and more preferably 1.1 to 4.0 times.

There is no particular limitation on the material of the sieve 22 in the case of separating the foreign substance and / or the coarse particles by the sieve 22. It is usually selected from resins, metals, and magnetic materials.

The movement form of the body 22 is not particularly limited, but a movement form such as a vibration type, an in-plane movement type, and an ultrasonic type can be used. In the case of the vibration type, it is preferable to vibrate only in the horizontal direction. The coarse particles transferred by air are trapped after removing the foreign particles and / or coarse particles.

(Composite particle for electrochemical device electrode)

The composite particles according to the present invention are obtained by a manufacturing method including at least a slurry production step, a granulation step and a removal step as described above.

That is, in the above-described embodiment, the transferring step is provided, but the transferring step may be omitted.

(Electrochemical device electrode)

An electrochemical device electrode (hereinafter sometimes simply referred to as " electrode ") using the composite particles of the present invention is formed by laminating an electrode active material layer containing composite particles on a current collector. Examples of the current collector material used for the electrode include metals, carbon, conductive polymers and the like, and examples of suitable materials include metals. Examples of the metal for the current collector include aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, and other alloys. The collector may be in the form of a film or a sheet. The thickness of the collector is arbitrarily selected depending on the purpose of use, and is preferably 1 to 200 占 퐉, more preferably 5 to 100 占 퐉, and still more preferably 10 to 50 占 퐉.

The electrode active material layer may be formed by forming an electrode material containing composite particles into a sheet and then laminating the electrode material on the current collector. Preferably, the electrode material including the composite particles is directly formed on the current collector to form an active material layer . As a method of forming the electrode active material layer made of an electrode material, there is a wet forming method such as a dry forming method such as a pressure forming method and a coating method, and a drying step is unnecessary, so that an electrode can be produced with high productivity, It is preferable to use a dry forming method in which it is easy to uniformly form a thick active material layer.

Examples of the dry molding method include a pressure molding method and an extrusion molding method (also referred to as paste extrusion). The pressure-molding method is a method of forming an electrode active material layer by densifying the electrode material by rearrangement and deformation by applying pressure to the electrode material. The extrusion molding method is a method in which an electrode material is extruded by an extrusion molding machine and molded into a film, a sheet, or the like, and the electrode active material layer can be successively molded with the elongate material. Of these, it is preferable to use a pressure molding method in view of the fact that it can be carried out with a simple facility. Examples of the pressure forming method include a roll press forming method in which an electrode material including composite particles is supplied to a roll type press forming apparatus by a feeding device such as a screw feeder to form an electrode active material layer, A method of adjusting the thickness of the electrode material by using a blade or the like and then forming the electrode material by a pressurizing device; a method of filling the electrode material into a mold and pressurizing the mold; and the like.

Of these press-molding methods, the roll pressing method is favorable. In this method, the electrode active material layer may be directly laminated on the current collector by sending the current collector to the roll simultaneously with the supply of the electrode material. The temperature at the time of molding is preferably 0 to 200 占 폚 and preferably 20 占 폚 or more higher than the glass transition temperature of the binder contained in the composite particles from the viewpoint of satisfactory adhesion between the electrode active material layer and the current collector desirable. In the roll pressing method, the shaping speed is preferably 0.1 to 40 m / min, more preferably 1 to 40 m / min from the viewpoint of improving the uniformity of the thickness of the electrode active material layer. Further, the press line pressure between the rolls is preferably 0.2 to 30 kN / cm, more preferably 0.5 to 10 kN / cm.

In order to eliminate variations in the thickness of the formed electrode and to increase the density of the electrode active material layer to increase its capacity, post-pressurization may be further performed if necessary. As a post-pressurizing method, a pressing process by a roll is generally used. In the roll press process, rolls of two cylindrical columns are arranged in parallel up and down at narrow intervals, and are rotated in opposite directions to press the electrodes therebetween. The roll may be used by controlling the temperature such as heating or cooling.

(Electrochemical device)

The electrochemical device uses the electrochemical device electrode obtained as described above in at least one of a positive electrode and a negative electrode, and further includes a separator and an electrolytic solution. Examples of the electrochemical device include a lithium ion secondary battery and a lithium ion capacitor. Hereinafter, the case where the electrochemical device is a lithium ion secondary battery will be described.

(Separator)

As the separator, for example, a microporous film or nonwoven fabric comprising a polyolefin resin such as polyethylene or polypropylene, or an aromatic polyamide resin; A porous resin coat including an inorganic ceramic powder; Etc. may be used. The thickness of the separator is preferably 0.5 to 40 占 퐉 from the viewpoint of workability in manufacturing a lithium ion battery.

(Electrolytic solution)

As the electrolyte solution for the lithium ion secondary battery, for example, a non-aqueous electrolyte solution in which a supporting electrolyte is dissolved in a non-aqueous solvent is used. As the supporting electrolyte, a lithium salt is preferably used. Lithium salts include, for _{example, LiPF 6, LiAsF 6, LiBF} 4, LiSbF 6, LiAlCl 4, LiClO 4, CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) ₂ NLi, (CF ₃ SO ₂ ) ₂ NLi, and (C ₂ F ₅ SO ₂ ) NLi. In particular, the _{LiPF 6, LiClO 4, CF 3} SO 3 Li indicating a high degree of dissociation easily soluble in solvents. These may be used singly or in combination of two or more in an arbitrary ratio. The higher the degree of dissociation of the supporting electrolyte, the higher the lithium ion conductivity. Thus, the lithium ion conductivity can be controlled depending on the type of the supporting electrolyte.

The concentration of the supporting electrolyte in the electrolytic solution is preferably 0.5 to 2.5 mol / L, depending on the type of the supporting electrolyte. Even if the concentration of the supporting electrolyte is excessively low or too high, there is a possibility that the ion conductivity is lowered.

The non-aqueous solvent is not particularly limited as long as it can dissolve the supporting electrolyte. Examples of the non-aqueous solvent include carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC) and methyl ethyl carbonate (MEC); esters such as? -butyrolactone and methyl formate; Ethers such as 1,2-dimethoxyethane and tetrahydrofuran; Sulfur-containing compounds such as sulfolane, dimethylsulfoxide and the like; And an ionic liquid which is also used as a supporting electrolyte. Among them, carbonates are preferable because of high dielectric constant and stable wide potential range. As the non-aqueous solvent, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio. In general, the lower the viscosity of the nonaqueous solvent, the higher the lithium ion conductivity. The higher the dielectric constant, the higher the solubility of the supporting electrolyte. Since both are in trade-off relationship, the lithium ion conductivity is controlled by the type and mixing ratio of the solvent It is good to use. The non-aqueous solvent may be a combination of all or part of hydrogen substituted with fluorine, or all of them may be used.

The electrolytic solution may contain an additive. As the additive, for example, a carbonate type such as vinylene carbonate (VC); Sulfur compounds such as ethylene sulfite (ES); And fluorine-containing compounds such as fluoroethylene carbonate (FEC). One kind of additives may be used alone, or two or more kinds of additives may be used in combination at an arbitrary ratio.

As a substitute for the electrolytic solution, for example, a polymer electrolyte such as polyethylene oxide or polyacrylonitrile; A gelated polymer electrolyte in which the polymer electrolyte is impregnated with an electrolytic solution; Inorganic solid electrolytes such as LiI and Li ₃ N; May be used.

The electrode and the separator are impregnated with an electrolytic solution to obtain an electrochemical device. Specifically, the electrode and the separator may be formed by winding, laminating or folding the electrode and the separator, if necessary, into a container, and then filling the container with an electrolytic solution. The electrode and the separator impregnated with an electrolytic solution may be stored in a container in advance. As the container, any known one such as a coin type, a cylindrical type, and a prism type can be used.

According to the method for producing composite particles for electrochemical device electrodes according to the present embodiment, it is possible to obtain composite particles in which the broadening of the particle size distribution is suppressed even in the case of mass production.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by these Examples at all. On the other hand, the parts and% in the present embodiment are based on weight unless otherwise specified.

In the examples and comparative examples, the particle size distribution, the long dry formability and the cycle characteristics of the composite particles were evaluated as follows.

≪ Particle size distribution of composite particles &

Measurement was carried out by a dry method using a microtrack (manufactured by Nikkiso). The results are shown in Table 1.

A: The particle size distribution is very sharp (less than 0.25 of half width to base length)

B: Particle size distribution is slightly sharp (ratio of half width to peak bottom length is 0.25 or more and less than 0.35)

C: Particle size distribution is slightly broad (ratio of half width to peak bottom length is from 0.35 to less than 0.50)

D: The particle size distribution is very broad (ratio of half width to peak bottom length is 0.50 or more) or particle size distribution of primary particles.

<Long-term dry formability>

The composite particles obtained in Examples and Comparative Examples were roll-molded into edged foils to confirm long-formability. The results are shown in Table 1.

A: Moldable without defects of 10 m or more

B: 10 m moldable, but defective

C: Moldability is not possible due to poor fluidity.

D: Moldability is not possible due to poor fluidity

<Cycle characteristics>

The prepared lithium ion secondary battery was allowed to stand for 24 hours, charged to 4.2 V at a charge / discharge rate of 0.1 C, and then discharged to 3.0 V to perform initial charge capacity C0. Charging and discharging were repeated under an environment of a temperature of 25 占 폚, and a capacity C2 after 100 cycles was measured. Then, a capacity retention rate? C expressed by? C = (C2 / C0) x 100 (%) was obtained. The higher the value of the capacity retention rate? C, the better the cycle characteristics. The results are shown in Table 1.

A: Capacity retention rate 90% or more

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

C: Capacity retention rate less than 80%

D: Impossible to measure

[Example 1]

(Preparation of Carboxy Cellulose Solution as Viscosity Adjusting Agent)

A 1% aqueous solution of carboxymethylcellulose (hereinafter sometimes referred to as "CMC") ("Cellogen BSH-12" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) having a solution viscosity of 8000 mPa · s was prepared.

(Production of negative electrode slurry)

100 parts of artificial graphite having an average particle size of 24.5 占 퐉 as an electrode active material for a negative electrode was put into a slurry tank 6 (see Fig. 1) (for example, a disper-mounted planetary mixer) 100 parts of a 1% aqueous solution of CMC was added thereto, adjusted to a solid content concentration of 53.5% by weight with ion-exchanged water, and stirred with a stirring blade 10 to mix at 25 캜 for 60 minutes. Next, the solid content concentration was adjusted to 40% by weight with ion-exchanged water, and the mixture was further mixed at 25 캜 for 15 minutes. Next, as a binder, SBR latex (BM-400B, manufactured by Nippon Zeon Co., Ltd.) was adjusted to a solid content concentration of 40% by weight, 2.9 parts of the resultant was stored at room temperature for 90 days, and the mixture was stirred by a stirring blade 10 And mixed for 10 minutes. This was degassed under a reduced pressure to obtain a slurry for a negative electrode (final solid concentration: 40% by weight) having good flowability and good fluidity.

(Assembly of assembled particles for negative electrode)

The slurry obtained as described above was granulated using a rotary disk 18 having a diameter of 85 mm using an assembling device 14 (see Fig. 1) (specifically, a spray dryer (manufactured by Okawara Chemical Industry Co., Ltd.) Spray drying and granulation were carried out under conditions of 25,000 rpm, a dry air temperature of 180 캜 and a temperature of 90 캜 at the particle collecting outlet, and cyclone recovery was carried out to obtain granulated granules for negative electrode. The volume average particle diameter of the obtained granulated particles (12) was 70 μm. On the other hand, the flow rate of dry air was controlled to 20 m / s by setting the cyclone differential pressure in the drying furnace 16 of the granulating device 14 to 1 kpa.

(Feeding and Removing Process of Assembled Particles for Negative Electrode)

The resultant granules for negative electrode were transferred to a vibrating body equipment by air and a sieve 22 having a sieve of 130 μm was provided in the vibrating vibrating machine unit. The coarse granulation granules were sieved to remove coarse particles, Composite particles were obtained. In the process of transferring the assembled particles to the vibrating body equipment, it was transferred by the flowing air through the pipe 20. The flow rate of the flowing air was controlled to 5 m / s and the meat ratio to 30 (coarse particle (kg / h) / air (kg / h)) by controlling the flow air amount to 0.5 Nm ³ / min.

(Packing step of negative electrode composite particles)

The resultant composite particles for negative electrode were cut out by a rotary valve and wrapped in a bag made of polyethylene.

(Preparation of negative electrode for lithium ion secondary battery)

The resultant negative electrode composite particles were applied to a roll (roll temperature of 100 占 폚, press line pressure of 4.0 kN / cm) of an electrolytic copper foil (thickness: 20 占 퐉) as a current collector on a roll (roll compacting surface heat roll, manufactured by Hirono Kiken Kogyo Co., μm), and molded into a sheet shape on an electrolytic copper foil as a current collector at a molding speed of 20 m / min to obtain a negative electrode for a lithium ion secondary battery having a negative electrode active material layer having a thickness of 80 μm.

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

Polyvinylidene fluoride (PVDF; "KF-1100" manufactured by Kureha Chemical Industries, Ltd.) as a positive electrode binder was added to 92 parts of LiCoO ₂ as a positive electrode active material (hereinafter abbreviated as "LCO" , 6 parts of acetylene black ("HS-100" manufactured by Denki Kagaku Kogyo) and 20 parts of N-methyl-2-pyrrolidone were added and mixed with a planetary mixer to obtain a positive electrode slurry. This positive electrode slurry was applied to an aluminum foil having a thickness of 18 mu m and dried at 120 DEG C for 30 minutes, followed by roll pressing to obtain a positive electrode for a lithium ion secondary battery having a thickness of 60 mu m.

(Preparation of separator)

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

(Production of lithium ion secondary battery)

As the exterior of the battery, an aluminum casing was prepared. The positive electrode for a lithium ion secondary battery obtained above was cut out into a square of 4 x 4 cm ² , and the surface of the current collector side was disposed so as to be in contact with the aluminum casing. On the surface of the positive electrode active material layer of the positive electrode for a lithium ion secondary battery, a square separator obtained as described above was disposed. The negative electrode for a lithium ion secondary battery obtained above was cut into a square of 4.2 x 4.2 cm ² and disposed on the separator such that the surface of the negative electrode active material layer side faced the separator. Further, a 1.0 M LiPF ₆ solution containing 2.0% of vinylene carbonate was charged. The solvent of the LiPF ₆ solution is a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC / EMC = 3/7 (volume ratio)). Further, in order to seal the openings of the aluminum packaging material, a heat-sealed at 150 ° C was used to close the aluminum casing to produce a laminate-type lithium ion secondary cell (laminate cell).

[Example 2]

(Preparation of Carboxy Cellulose Solution as Viscosity Adjusting Agent)

A 1% aqueous solution of carboxymethylcellulose ("Cellogen BSH-12" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) having a solution viscosity of 8000 mPa · s was prepared.

(Preparation of slurry for positive electrode)

100 parts of LCO as a positive electrode active material and 4.0 parts of acetylene black (HS-100, manufactured by Denki Kagaku Kogyo K.K.) as carbon fine particles were added to a slurry tank 6 (see Fig. 1) (for example, Followed by dry blending for 10 minutes. Subsequently, 1.0% of a 1% aqueous solution of carboxymethylcellulose prepared above in terms of solid content was added. Subsequently, the ion-exchanged water was added until the solid content reached 85% by weight, and the mixture was stirred by a stirring blade 10 to be kneaded at 30 DEG C for 30 minutes. 1 part of a conjugated diene latex (BM-600B (manufactured by Nippon Zeon)) having a solids content of 40% as a binder was added to a mixture of the positive electrode active material and the carbon fine particles as a binder. After the introduction of the binder, the mixture was stirred by a stirring blade 10 for uniform dispersion and kneaded for 3 minutes to obtain a positive electrode slurry (final solid concentration of 85% by weight).

(Assembly of assembled particles for positive electrode)

The slurry obtained as described above was granulated using a rotary disk 18 having a diameter of 85 mm using an assembling device 14 (see Fig. 1) (specifically, a spray dryer (manufactured by Okawara Chemical Industry Co., Ltd.) Spray drying and granulation were carried out under conditions of 25,000 rpm, a dry air temperature of 180 캜, and a temperature of the particle recovery outlet of 90 캜, and cyclone recovery was carried out to obtain granulated granules for positive electrode. The volume average particle diameter of the obtained granulated particles (12) was 40 占 퐉. On the other hand, the flow rate of dry air was controlled to 20 m / s by setting the cyclone differential pressure in the drying furnace 16 of the granulating device 14 to 1 kpa.

(Feeding and Removing Process of Positive Electrode Assembly Particles)

The resultant granulated particles for positive electrode were transferred to a vibrating body equipment by air and a body 22 having a sieve of 130 μm was placed on the vibrating vibrating machine. The coarse granulated particles for the positive electrode were sieved to remove coarse particles, Composite particles were obtained. In the process of transferring the assembled particles to the vibrating body equipment, it was transferred by the flowing air through the pipe 20. The flow rate of the flowing air was controlled to 5 m / s and the weight ratio to 30 (granulated particles (kg / h) / air (kg / h)) by controlling the flow air amount to 0.5 Nm ³ / min.

(Packing step of positive electrode composite particles)

The resultant composite particles for positive electrode were cut out by a rotary valve and wrapped in a bag made of polyethylene.

(Preparation of positive electrode for lithium ion secondary battery)

The positive electrode composite particles thus obtained were subjected to a press roll (roll temperature: 100 占 폚, press (pressure kneading surface heat roll) manufactured by Hirano Giken Co., Ltd.) using a quantitative feeder (Nikka Spray KV manufactured by Nikka Corporation) Line pressure 500 kN / m). An aluminum foil having a thickness of 20 占 퐉 was inserted between press rolls, and the positive electrode composite particles supplied from the quantitative feeder were adhered to an aluminum foil (current collector) and pressed at a molding speed of 1.5 m / A positive electrode having an active material layer was obtained.

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

96 parts of artificial graphite (average particle size: 24.5 占 퐉, distance between graphite layers (plane spacing of (002) plane (d value) of 0.354 nm by X-ray diffraction method: 0.354 nm), 1.5% aqueous solution of carboxymethylcellulose (DN- (BM-400B) was mixed with 1.0 part by weight of a polyvinyl butyral latex (trade name, available from Daicel Chemical Industries, Ltd.) in an amount of 1.0 part by weight in terms of solid content, and ion-exchanged water was added thereto so as to have a solid content concentration of 55% The slurry for the negative electrode was applied to a copper foil having a thickness of 18 mu m and dried at 120 DEG C for 30 minutes, followed by roll pressing to give a thickness of 50 μm negative electrode was obtained.

(Preparation of separator)

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

(Production of lithium ion secondary battery)

As the exterior of the battery, an aluminum casing was prepared. The positive electrode for a lithium ion secondary battery obtained above was cut out into a square of 4 x 4 cm ² , and the surface of the collector side was disposed so as to be in contact with the aluminum casing. On the surface of the positive electrode active material layer of the positive electrode for a lithium ion secondary battery, a square separator obtained as described above was disposed. The negative electrode for a lithium ion secondary battery obtained above was cut into a square of 4.2 x 4.2 cm ² and disposed on the separator such that the surface of the negative electrode active material layer side faced the separator. Further, a 1.0 M LiPF ₆ solution containing 2.0% of vinylene carbonate was charged. The solvent of the LiPF ₆ solution is a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC / EMC = 3/7 (volume ratio)). Further, in order to seal the openings of the aluminum packaging material, a heat-sealed at 150 ° C was used to close the aluminum casing to produce a laminate-type lithium ion secondary cell (laminate cell).

[Example 3]

The procedure of preparation of the negative electrode slurry, assembly of the negative electrode granules, transfer and removal of coarse particles, preparation of the negative electrode for the lithium ion secondary battery, and preparation of the lithium ion secondary battery were carried out in the same manner as in Example 1, .

[Example 4]

A negative electrode slurry was prepared in the same manner as in Example 1. As in Example 1, except that the obtained negative electrode slurry was used and the flow rate of the dry air was controlled to 15 m / s by setting the cyclone differential pressure of the spray drier to 0.8 kPa, Transfer of granulated granules, removal of coarse particles, production of a negative electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery.

[Example 5]

A negative electrode slurry was prepared in the same manner as in Example 1. Using the obtained negative electrode slurry and controlling the flow rate of dry air to 30 m / s by setting the cyclone differential pressure of the spray dryer to 1.3 kPa, the negative electrode assembly particles were assembled, Transfer of granulated granules, removal of coarse particles, production of a negative electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery.

[Example 6]

The slurry for the negative electrode and the assembled particles for the negative electrode were assembled in the same manner as in Example 1. (Kg / h) / air (kg / h) by setting the flow rate of the flowing air to 10 m / s and the ratio of the air to the air (kg / h) by setting the flow air amount to 1.0 Nm ³ / ), The transfer of coarse particle assemblies and removal of coarse particles, the production of a negative electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1, respectively.

[Comparative Example 1]

The procedure of preparation of the negative electrode slurry, assembly of the negative electrode granules, transfer and removal of coarse particles, preparation of the negative electrode for the lithium ion secondary battery, and preparation of the lithium ion secondary battery were carried out in the same manner as in Example 1, .

[Comparative Example 2]

Preparation of a positive electrode slurry, assembly of positive electrode granules, transfer and removal of coarse particles, preparation of a positive electrode for a lithium ion secondary battery, and preparation of a lithium ion secondary battery were carried out in the same manner as in Example 2 except that the final solid content concentration was changed to 93 wt% .

[Comparative Example 3]

A negative electrode slurry was prepared in the same manner as in Example 1. The obtained positive electrode slurry was used and the flow rate of dry air was controlled at 40 m / s by setting the cyclone differential pressure of the spray drier to 1.5 kPa to assemble the negative electrode granulated particles, Transfer of granulated granules, removal of coarse particles, production of a negative electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery.

[Comparative Example 4]

A negative electrode slurry was prepared in the same manner as in Example 1. The obtained positive electrode slurry was used and the flow rate of the dry air was controlled to 5 m / s by setting the cyclone differential pressure of the spray drier to 0.5 kpa to assemble the negative electrode granulated particles, Transfer of granulated granules, removal of coarse particles, production of a negative electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery.

As shown in Table 1, a method for producing composite particles for an electrochemical device electrode includes a slurry production step of dispersing or dissolving an electrode active material and a binder in a medium to obtain a slurry, a granulation step of spray- And a removal step of removing foreign matter and / or coarse particles from the granulated particles, wherein a solid concentration of the slurry obtained in the slurry production step is 20 wt% or more and 90 wt% or less, When the flow rate of dry air at the time of drying is not less than 10 m / s and not more than 40 m / s, the obtained composite particles have good particle size distribution and dry formability, The characteristics were good.

Claims (3)

A method for producing composite particles for an electrochemical device electrode,
A slurry producing step of dispersing or dissolving the electrode active material and the binder in the medium to obtain a slurry,
An assembling step of spray-drying the slurry to obtain granulated particles,
And removing the foreign particles and / or coarse particles from the granulated particles,
The solid concentration of the slurry obtained in the slurry producing step is 20 wt% or more and 90 wt% or less,
Wherein the flow rate of dry air at the time of spray drying in the assembling step is not less than 10 m / s and not more than 40 m / s. The method according to claim 1,
And a conveying step of conveying the granulated particles by air after the granulating step,
Wherein the air flow rate in the transfer step is not less than 0.5 m / s and not more than 20 m / s. 3. The method of claim 2,
In the transferring step,
The meat ratio calculated by dividing the mass flow rate (kg / h) of the granulated particles per unit time by the mass flow rate (kg / h) of the air consumed for transporting the granulated particles per unit time is not less than 5 and not more than 150, (Method for manufacturing composite particles for device electrodes).

Images