KR102311781B1 - Production method for complex particles for use in electrode of electrochemical element - Google Patents

Abstract

A method for producing composite particles for an electrode of an electrochemical device, comprising: a slurry production step of dispersing or dissolving an electrode active material and a binder in a medium to obtain a slurry (4); and a granulation step of spray-drying the slurry to obtain granulated particles (12); , a removal step of removing foreign substances and/or coarse particles from the granulated 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, and spray drying in the granulation step The flow velocity of dry air in the city is 10 m/s or more and less than 40 m/s.

Description

Manufacturing method of composite particles for electrochemical device electrodes TECHNICAL FIELD

The present invention relates to a method for producing a composite particle for an electrochemical element electrode.

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

Further improvements, such as reduction in resistance, increase in capacity, and improvement in mechanical properties and productivity, are demanded for these electrochemical elements in accordance with the expansion and development of applications. In such a situation, a manufacturing method with higher productivity is required also for an electrode for an electrochemical device, and various improvements are being made to a manufacturing method capable of high-speed molding and a material for an electrode for an electrochemical device suitable for the manufacturing method. .

The electrode for electrochemical elements is a thing formed by laminating|stacking on an electrical power collector the electrode active material layer formed by binding an electrode active material and the electrically conductive material used as needed normally with a binder normally. The electrode for an electrochemical device was manufactured by applying a slurry composition containing an electrode active material, a binder, a conductive material, etc. on a current collector and removing the solvent by heat or the like, but due to migration of the binder, etc., It was difficult to manufacture a uniform electrochemical device. Moreover, this method has the subject that cost is high, a working environment worsens, and a manufacturing apparatus becomes large.

On the other hand, it is proposed to obtain a composite particle and to obtain a uniform electrochemical element by powder-molding. As a manufacturing method of such a composite particle for electrochemical element electrodes, for example, in patent document 1, manufacturing including the process of spray-drying and granulating the slurry which consists of an electrode active material, a conductive material, a dispersion-type binder, and a soluble resin. A method is disclosed. However, mass production of composite particles for electrochemical device electrodes has not been considered. When further scale-up by mass production was examined, it was found that the formability (dry formability) of the obtained composite particles and the characteristics (cycle characteristics) of the battery using the molded electrode decreased. It was found that the cause was due to broadening of the particle size distribution in the granulation process of the composite particles.

Japanese Laid-Open Patent Publication No. 2006-303395

It is an object of the present invention to provide a method for producing composite particles for electrochemical device electrodes capable of suppressing broadening of particle size distribution even when mass-produced.

As a result of intensive studies to solve the above problems, the present inventors used a slurry prepared at a predetermined concentration including an electrode active material and a binder, and in the granulation process of composite particles, the flow rate of dry air used during spray drying By making it into a predetermined range, it discovered that the said objective could be achieved, and completed this invention.

That is, according to the present invention,

(1) A method for manufacturing composite particles for an electrode of an electrochemical device, comprising: a slurry preparation step of dispersing or dissolving an electrode active material and a binder in a medium to obtain a slurry; a granulation step of spray drying the slurry to obtain granulated particles; a removal step of removing foreign substances and/or coarse particles from the particles; A method for producing composite particles for an electrochemical device electrode having an air flow velocity of 10 m/s or more and less than 40 m/s,

(2) After the granulation step, there is a transport step of transporting the granulated particles with air, and the electrochemical according to (1), wherein the air flow velocity in the transport step is 0.5 m/s or more and 20 m/s or less. A method for producing composite particles for device electrodes,

(3) Meat 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 in the transfer step The manufacturing method of the composite particle for electrochemical element electrodes as described in (2) whose ratio is 5 or more and 150 or less is provided.

ADVANTAGE OF THE INVENTION According to this invention, even when mass-producing, the manufacturing method of the composite particle for electrochemical element electrodes which can suppress the broadening of a particle size distribution can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the composite particle manufacturing apparatus used for the manufacturing method of the composite particle for electrochemical element electrodes which concerns on embodiment of this invention.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the manufacturing method of the composite particle for electrochemical element electrodes (Hereinafter, it may simply be called "composite particle") which concerns on embodiment of this invention is demonstrated. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the composite particle manufacturing apparatus used for the manufacturing method of the composite particle for electrochemical element electrodes which concerns on embodiment of this invention.

As shown in Fig. 1, the composite particle production apparatus 2 includes a slurry tank 6, a slurry tank 6 for producing a slurry 4 by stirring the raw material introduced through the raw material input pipe 8 with a stirring blade 10, a slurry ( 4) a granulation device 14 for producing the granulated particles 12, a pipe 20 for transporting the granulated particles 12 produced by the granulating device 14, and the granulated particles transported through the pipe 20 ( A sieve 22 for removing foreign substances and/or coarse particles from 12) and a storage tank 24 for storing the composite particles 26 for electrochemical element electrodes are provided.

Here, the granulation apparatus 14 is equipped with the drying furnace 16, and the rotary disk 18 which sprays the slurry 4 while rotating is provided in the inside of the drying furnace 16. As shown in FIG. Moreover, the air inlet 17a is provided in the upper part of the drying furnace 16, and the connection part (not shown) with the piping 20 is provided in the lower part of the drying furnace 16. As shown in FIG. In the middle of the pipe 20, two cyclones (cyclones 30, 34) for separating the granulated particles 12 from the air and for discharging a part of the air are installed, and the cyclones 30 and 34 have an air outlet ( 30a and 34a) are provided respectively. In addition, a recovery tank 32 is provided on the downstream side of the cyclone 30 , 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, the manufacturing method of the composite particle for electrochemical element electrodes using the composite particle manufacturing apparatus 2 is demonstrated.

(Slurry making process)

In the slurry preparation process of this invention, an electrode active material and a binder are disperse|distributed or melt|dissolved in a medium, and a slurry is obtained.

The slurry preparation process is performed in the slurry tank 6 of the composite particle manufacturing apparatus 2 shown in FIG. And it can be obtained by stirring with the stirring blade 10.

Here, the slurry 4 can be obtained by dispersing or dissolving an electrode active material and a binder in a medium. Moreover, the slurry 4 may contain the viscosity modifier and carbon microparticles|fine-particles as needed.

In addition, you may perform mixing by a stirring type, a shaking type, a rotary type, etc. instead of stirring using the stirring blade 10 in the slurry tank 6 . Moreover, you may use dispersion-kneading apparatuses, such as a homogenizer, a ball mill, a sand mill, a roll mill, a planetary mixer, and a planetary kneader.

The method or order of dispersing or dissolving the electrode active material, the binder, and optionally the viscosity modifier or carbon fine particles used in the medium is not particularly limited, and for example, the electrode active material, the binder, and the viscosity modifier used as needed in the medium. a method of adding and mixing carbon fine particles; A method of dissolving a viscosity modifier in a medium, adding and mixing a binder dispersed in the medium, and finally adding and mixing an electrode active material and carbon fine particles; a method of adding and mixing an electrode active material and carbon fine particles to a binder dispersed in a medium, and adding and mixing a viscosity modifier dissolved in a medium to the mixture; a method of mixing the electrode active material and carbon fine particles used as necessary with powders, then adding an appropriate amount of a viscosity modifier and a medium, kneading and dispersing, and then adding a medium and a binder for adjusting the viscosity; a method of dispersing the electrode active material and carbon fine particles used as necessary in a medium in which the viscosity modifier is dissolved, followed by adding a binder; and the like.

The viscosity of the slurry obtained by a slurry preparation process becomes like this. Preferably it is 100-5000 mPa*s, More preferably, it is 100-3000 mPa*s, More preferably, it is 100-2000 mPa*s. In addition, the viscosity of a slurry is the value measured at the temperature of 25 degreeC, and rotation speed of 60 rpm using a B-type viscometer.

In addition, the solid content concentration of the slurry obtained by the slurry preparation process is 20 weight% or more and 90 weight% or less, Preferably it is 30 weight% or more and 90 weight% or less, More preferably, it is 35 weight% or more and 90 weight%. When the solid content concentration of the slurry is too high, the viscosity cannot be within the above range, and the fluidity also deteriorates. In addition, when the solid content concentration of the slurry is too low, the productivity of the composite particles decreases. In addition, the stability of the slurry deteriorates.

(electrode active material)

The electrode active material used by this invention is suitably selected according to the kind of electrochemical element manufactured. For example, when the electrochemical element manufactured is a lithium ion secondary battery, as a positive electrode active material used for the positive electrode of a lithium ion secondary battery, the metal oxide which can dope/dedope lithium ion reversibly is mentioned. Examples of such metal oxides include lithium cobaltate (hereinafter, may be referred to as "LCO"), lithium nickelate, lithium manganate, lithium iron phosphate (hereinafter may be referred to as "LFP"), Lithium manganese phosphate, lithium vanadium phosphate, lithium iron vanadate, nickel-manganese-lithium cobaltate (hereinafter sometimes referred to as "NMC"), nickel-lithium cobaltate, nickel-lithium manganate, lithium iron-manganate , iron-manganese-lithium cobaltate, lithium iron silicate, iron silicate-lithium manganese, vanadium oxide, copper vanadate, niobium oxide, titanium sulfide, molybdenum oxide, molybdenum sulfide, and the like. In addition, the positive electrode active material illustrated above may be used independently according to a use suitably, and may be used in mixture of multiple types. Moreover, lithium iron phosphate and lithium manganese phosphate are also mentioned. Moreover, polymers, such as polyacetylene, poly-p-phenylene, and polyquinone, are mentioned. Among these, it is preferable to use LCO, NMC, or LFP.

Here, in the present invention, dope means occlusion, support, adsorption or insertion, and is defined as a phenomenon in which lithium ions and/or anions enter the positive electrode, or a phenomenon in which lithium ions enter the negative electrode. In addition, de-doping also means release, desorption, and desorption, and is defined as referring to the opposite phenomenon of doping.

Moreover, as a negative electrode active material used for the negative electrode of a lithium ion secondary battery as a counter electrode of the positive electrode of the above-mentioned lithium ion secondary battery, graphitizable carbon, hardly graphitizable carbon, activated carbon, pyrolysis carbon, etc. Low crystalline carbon (amorphous carbon), graphite (natural graphite, artificial graphite), carbon nanowall, carbon nanotube, or composite carbon material of carbon with different physical properties, alloy-based material such as tin or silicon, silicon oxide, Oxides, such as tin oxide, vanadium oxide, and lithium titanate, polyacene, etc. are mentioned. Among these, it is preferable to use graphite and activated carbon. In addition, the electrode active material illustrated above may be used independently according to a use suitably, and may be used in mixture of multiple types.

(bookbinder)

The binder used in the present invention is not particularly limited as long as it is a compound capable of binding the above-described electrode active materials to each other, but in the present invention, a dispersed binder having a property of being dispersed in a medium is preferable. Examples of the dispersed binder include high molecular compounds such as silicone-based polymers, fluorine-containing polymers, conjugated diene-based polymers, acrylate-based polymers, polyimides, polyamides, and polyurethanes. Among these, conjugated dienes Polymers and acrylate polymers are preferred.

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

An acrylate-type polymer is a polymer containing a (meth)acrylic acid ester monomeric unit. Among them, a polymer comprising a (meth)acrylic acid ester monomer unit and further comprising at least one of an α,β-unsaturated nitrile monomer unit and an acidic functional group-containing monomer unit is preferable, and an α,β-unsaturated nitrile monomer unit and acid A polymer containing both of the functional group-containing monomer units is more preferable. By using the acrylate-based polymer including the monomer unit, the binding force of the binder may be further improved. In addition, in this specification, "a monomer unit is included" means that "the structural unit derived from a monomer is contained in the polymer obtained using the monomer".

Examples of the (meth)acrylic acid ester monomer that can be used in the preparation of the acrylate-based polymer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, Acrylic acids such as pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, and stearyl acrylate alkyl esters; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate Alkyl methacrylate, such as rate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate Ester etc. are mentioned. Among these, when used in a lithium ion secondary battery as an electrode, it does not elute into the electrolyte and swells appropriately in the electrolyte, thereby exhibiting good ionic conductivity and extending the battery life. It is preferable that carbon number of the alkyl group to do is 4-13, and n-butyl acrylate and 2-ethylhexyl acrylate are especially preferable. In addition, these may be used independently and may use 2 or more types together.

The content ratio 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, preferably 95% by weight or less, more preferably 90% by weight or less. By making the content rate of the monomeric unit derived from a (meth)acrylic acid ester monomer into 50 weight% or more, the softness|flexibility of a binder can be made high and an electrode can be made hard to break. Moreover, by setting it as 95 weight% or less, the mechanical strength and binding property as a binder can be improved.

As the α,β-unsaturated nitrile monomer, for improving mechanical strength and binding property, for example, acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is particularly preferable. In addition, these may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the α,β-unsaturated nitrile monomer unit in the acrylate polymer is preferably 3% by weight or more, more preferably 5% by weight or more, preferably 40% by weight or less, more preferably is 30% by weight or less. When the content ratio of the α,β-unsaturated nitrile monomer unit is 3% by weight or more, the mechanical strength as a binder can be improved, and the adhesion between the electrode active material and the current collector or between the electrode active materials can be enhanced. Moreover, by setting it as 40 weight% or less, the softness|flexibility of a binder can be made high, and an electrode can be made hard to break.

Examples of the acidic functional group-containing monomer usable for producing 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.

As a monomer which has a carboxylic acid group, monocarboxylic acid and its derivative(s), and dicarboxylic acid, its acid anhydride, these derivatives, etc. are mentioned. As monocarboxylic acid, acrylic acid, methacrylic acid, a crotonic acid, etc. are mentioned. Examples of the monocarboxylic acid derivative include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, and β-diaminoacrylic acid. can be heard As dicarboxylic acid, a maleic acid, a fumaric acid, itaconic acid, etc. are mentioned. As an acid anhydride of dicarboxylic acid, maleic anhydride, acrylic acid anhydride, methyl maleic anhydride, dimethyl maleic anhydride, etc. are mentioned. Examples of the dicarboxylic acid derivative include methyl allyl maleate, diphenyl maleate, nonyl maleate, maleic acid such as methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloromaleic acid, dichloromaleic acid, and fluoromaleic acid. and maleic acid esters such as decyl, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate.

Examples of the monomer having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth)allylsulfonic acid, styrenesulfonic acid, (meth)acrylic acid-2-ethylsulfonate, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy- 2-hydroxypropanesulfonic acid etc. are mentioned. In addition, in this specification, "(meth)allyl" means allyl and/or methallyl.

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

Among these, as the acidic functional group-containing monomer, acrylic acid, methacrylic acid, methyl methacrylate, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), phosphoric acid 2-((meth)acryloyloxy ) ethyl is preferred. Furthermore, from a viewpoint that the storage stability of an acrylate type polymer can be made high, acrylic acid, methacrylic acid, and itaconic acid are preferable, and itaconic acid is especially preferable. In addition, these may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the acidic functional group-containing monomer unit in the acrylate polymer is preferably 0.5% by weight or more, more preferably 1% by weight or more, particularly preferably 1.5% by weight or more, and preferably 5% by weight or more. % or less, more preferably 4 wt% or less. By making the content rate of an acidic functional group containing monomeric unit into 0.5 weight% or more, binding property as a binder can be improved and cycling characteristics of a lithium ion secondary battery can be improved. Moreover, by setting it as 5 weight% or less, the manufacturing stability and storage stability of an acrylate type polymer can be made favorable.

Here, in addition to the above-described monomeric unit, the acrylate-type polymer may contain the crosslinkable monomeric unit. As the crosslinkable monomer, for example, a monomer containing an epoxy group, a monomer containing a carbon-carbon double bond and an epoxy group, a monomer containing a halogen atom and an epoxy group, a monomer containing an N-methylolamide group, oxetanyl and a monomer containing a group, a monomer containing an oxazoline group, a polyfunctional monomer having two or more olefinic double bonds, and the like.

In the acrylate-based polymer used as the binder, the content ratio of the crosslinkable monomer unit is that the acrylate-based polymer exhibits moderate swelling property with respect to the electrolyte solution, and in particular, the rate characteristics and cycle characteristics of the lithium ion secondary battery can be further improved. From the viewpoint of being present, it is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, preferably 0.5% by weight or less, and more preferably 0.3% by weight or less.

In addition, the acrylate-type polymer may contain the monomeric unit derived from the monomer other than what was mentioned above. As such a monomeric unit, the polymeric unit derived from a vinyl monomer, and a hydroxyl-containing monomeric unit are mentioned. Examples of the vinyl monomer include carboxylate esters having two or more carbon-carbon double bonds such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; halogen atom-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; Heterocyclic-containing vinyl compounds, such as N-vinylpyrrolidone, a vinylpyridine, and vinylimidazole;; is mentioned. Examples of the hydroxyl group-containing monomer include ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-butene-1-ol and 5-hexen-1-ol, acrylic acid-2-hydroxyethyl, acrylic acid-2-hydroxypropyl; Ethylene such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, and di-2-hydroxypropyl itaconic acid Alkanol esters of sexually unsaturated carboxylic acids, general formula CH ₂ =CR ¹ -COO-(C _n H _{2n -1} O) _m -H (m is an integer from 2 to 9, n is an integer from 2 to 4, R ¹ represents hydrogen or a methyl group), esters of polyalkylene glycol and (meth)acrylic acid, 2-hydroxyethyl-2'-(meth)acryloyloxyphthalate, 2-hydroxyethyl- Vinyls, such as mono(meth)acrylic acid esters of dihydroxy ester of dicarboxylic acid, such as 2'-(meth)acryloyloxysuccinate, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether Ethers, (meth) allyl-2-hydroxyethyl ether, (meth) allyl-2-hydroxypropyl ether, (meth) allyl-3-hydroxypropyl ether, (meth) allyl-2-hydroxybutyl ether Mono (meth) allyl ethers of alkylene glycol, such as (meth) allyl-3-hydroxybutyl ether, (meth) allyl-4-hydroxybutyl ether, and (meth) allyl-6-hydroxyhexyl ether; Polyoxyalkylene glycol (meth) monoallyl ethers such as diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether, glycerin mono (meth) allyl ether, (meth) allyl-2-chloro Mono (meth) allyl ether of halogen and hydroxy substituents of (poly) alkylene glycol, such as -3-hydroxypropyl ether and (meth) allyl-2-hydroxy-3-chloropropyl ether, eugenol, iso Mono (meth) allyl ether of polyhydric phenols such as eugenol and its halogen substitution products, (meth) allyl-2-hydroxyethyl thioether and alkylene glycol such as (meth) allyl-2-hydroxypropyl thioether ( Meth) allyl thioethers, etc. are mentioned. In addition, these may be used individually by 1 type, and may be used in combination of 2 or more type.

Here, the manufacturing method of binders, such as an acrylate type polymer mentioned above, is not specifically limited, For example, any method, such as a solution polymerization method, suspension polymerization method, a block polymerization method, an emulsion polymerization method, may be used. Among these, the emulsion polymerization method using an emulsifier is preferable. On the other hand, when manufacturing a binder using an emulsion polymerization method, it is preferable to use polyoxyethylene type surfactant at least as surfactant to be added as an emulsifier used for superposition|polymerization. In addition, addition polymerization, such as ionic polymerization, radical polymerization, and living radical polymerization, can be used as a polymerization method. Moreover, as a polymerization initiator, a known polymerization initiator, for example, what was described in Unexamined-Japanese-Patent No. 2012-184201 can be used.

It is preferable that the dispersion-type binder used by this invention has a particulate-form shape. By being particulate, binding property is good, and the fall of the capacity|capacitance of the produced electrode, and deterioration by repetition of charging/discharging can be suppressed. As a binder, the thing of the state in which the binder was disperse|distributed in water like latex, for example, and the thing obtained by drying such a dispersion liquid are mentioned.

The volume average particle diameter of the dispersed binder used in the present invention is preferably 0.001 to 100 µm, more preferably 10 to 1000 nm, further preferably from the viewpoint of improving the strength and flexibility of the electrode for an electrochemical device obtained. It is usually 50-500 nm.

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

(viscosity modifier)

The slurry obtained by the slurry preparation process of this invention may contain the viscosity modifier as needed. Examples of the viscosity modifier include cellulose derivatives such as carboxymethyl cellulose (hereinafter, may be referred to as "CMC"); poly(meth)acrylates such as sodium poly(meth)acrylate; polyvinyl alcohol, modified polyvinyl alcohol, polyethylene oxide; and polyvinylpyrrolidone, polycarboxylic acid, oxidized starch, phosphoric acid starch, casein, various modified starches, chitin, and chitosan derivatives. Among these, CMC is preferable. It is preferable to use 0.5-2 weight part of viscosity modifiers with respect to 100 weight part of said electrode active materials, It is more preferable to use 0.7-1.5 weight part.

(carbon fine particles)

The slurry obtained in the slurry preparation process of this invention may contain the carbon microparticles|fine-particles as needed.

As the carbon fine particles, conductive carbons such as furnace black, acetylene black, and Ketjen black (registered trademark of Akzo Nobel Chemicals Best Lotin Pennote Shop), carbon nanotubes, carbon nanohorn, and graphene are preferably used. Among these, acetylene black is more preferable. The average particle diameter of the carbon fine particles is not particularly limited, but from the viewpoint of expressing sufficient conductivity with a smaller amount of use, it is preferably smaller than the average particle diameter of the electrode active material, preferably 0.001 to 10 µm, more preferably 0.005 to 5 µm, more preferably 0.01 to 1 µm.

To [ the usage-amount of carbon fine particle in the case of adding carbon fine particle / 100 weight part of electrode active materials ], Preferably it is 1-10 weight part, More preferably, it is 1-5 weight part. When there is too much usage-amount of carbon fine particle, it will become difficult to produce a slurry. Moreover, when there is too little usage-amount of carbon fine particle, there exists a possibility that the resistance of the electrochemical element obtained may rise.

(media)

As for the medium used for the slurry of this invention, it is preferable to use water. In addition, in this invention, as long as it is a range which does not impair the dispersion stability of a slurry, you may use what mixed the hydrophilic solvent with water as a medium. Methanol, ethanol, N-methylpyrrolidone etc. are mentioned as a hydrophilic solvent, It is preferable that it is 5 weight% or less with respect to water.

(Assembly process)

In the granulation process of this invention, granulated particles are obtained by spray-drying the slurry obtained in the slurry preparation process. The granulation process can be implemented using the granulation apparatus 14 of the composite particle manufacturing apparatus 2 shown in FIG. 1, for example. That is, granulated particles 12 can be obtained by spraying the slurry 4 obtained in the slurry preparation step while rotating the rotary disk 18 installed in the drying furnace 16 . Here, in the granulated particles 12, each of the electrode active material and the binder does not exist as independent particles, but one particle is formed by two or more components including the electrode active material and the binder as constituent components. will be. Specifically, a plurality of individual particles of the two or more components are combined to form secondary particles, and a plurality (preferably several to tens) of electrode active materials are bound by a binder to form particles. it is preferable

In addition, the shape of the granulated particles is preferably substantially spherical from the viewpoint of fluidity. That is, the minor axis of the granulated particles is L _s , and the major axis is L _l , L _a = (L _s + L _l )/2, and (1 - (L _l) - When _{the value of L s} )/L _a ) x 100 is defined as the sphericity (%), the sphericity is preferably 80% or more, and more preferably 90% or more. Here, the minor _{axis L s} and the major axis L _l are values measured from the scanning electron micrograph image.

In addition, the volume average particle diameter of the granulated particles is preferably 10 to 200 µm, more preferably 20 to 180 µm, still more preferably 30 to 170 µm. The average particle diameter of the granulated particles is a volume average particle diameter calculated by measuring with a laser diffraction particle size distribution analyzer (eg, Microtrac; manufactured by Nikkiso Corporation).

Spray drying is a method of spraying a slurry in dry air and drying it. An atomizer is mentioned as an apparatus used for spraying of a slurry. In the case of using a rotating disk type atomizer, the slurry is introduced into the approximately center of the disk rotating at high speed, and the slurry is sent out of the disk by the centrifugal force of the disk, and the slurry is made into a mist at that time. In the rotating disk method, the rotation speed of the disk depends on the size of the disk, preferably 5,000 to 30,000 rpm, more preferably 15,000 to 30,000 rpm. The lower the rotational speed of the master, the larger the spray droplets, and the larger the average particle diameter of the resulting composite particles.

The temperature of the slurry to be sprayed is preferably room temperature, but may be heated to a temperature higher than room temperature. Moreover, the temperature of the drying air at the time of spray drying becomes like this. Preferably it is 25-250 degreeC, More preferably, it is 50-200 degreeC, More preferably, it is 80-200 degreeC.

Here, the flow velocity of the dry air is 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/s or more and 30 m/s or less, further preferably It is preferably 10 m/s or more and 25 m/s or less. If the flow rate of the dry air is too high, the granulated particles are destroyed. In addition, when the flow rate of the dry air is too slow, the productivity of the granulated particles decreases. On the other hand, the flow rate of the dry air is 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) differential pressure of the air outlet 30a).

(Transfer process)

The composite particle for electrochemical element electrodes of this invention may include the conveyance process. In the transfer step, the granulated particles produced in the granulation step are transferred into the pipe 20 by air. Here, in a conveyance process, it is preferable to perform conveyance by the flowing air through the piping 20. As shown in FIG. Moreover, in a conveyance process, it is preferable to convey at low speed and high density. In order to transport the granulated particles at low speed and high density by flowing air through the pipe 20, specifically, the granulated particles separated from the air are recovered in the cyclone 30 located on the drying furnace 16 side. Once recovered to the tank 32, it is transferred by pressurizing it as it is in a high-density state.

The flow velocity of the flowing air at the time of transport is determined by the amount of air flowing in from the air inlet 17b in the pipe 20 shown in FIG. 1 and the cyclone 34 located further away from the drying furnace 16 among the two cyclones. Although controllable by the amount of air flowing out from the air outlet 34a in the is 1 m/s or more and 15 m/s or less, particularly preferably 1 m/s or more and 8 m/s or less. If the flow velocity of the flowing air during transport is too high, there is a risk that the granulated particles may be destroyed. In addition, if the flow rate of the flowing air during transport is too slow, the productivity of the granulated particles deteriorates.

In addition, the density in a conveyance process can be prescribed|regulated by the high ratio at the time of conveyance. The meat ratio at the time of transfer becomes like this. Preferably it is 5-150, More preferably, it is 10-150. Here, the high ratio 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 transport of the granulated particles per unit time. The larger the value of the meat ratio is, the more granulated particles can be transported with a small amount of air, and the efficiency is good. When the meat ratio is too small, there is a fear that the granulated particles are destroyed during transport.

(removal process)

In the removal step of the present invention, foreign substances and/or coarse particles are removed from the granulated particles obtained in the granulation step or the granulated particles transported in the transport step. The method for removing foreign substances and/or coarse particles from the granulated particles is not particularly limited, but it is preferable to remove the foreign substances and/or coarse particles by the sieve 22 (see FIG. 1 ). By removing foreign substances and/or coarse particles from the granulated particles, the composite particles 26 for electrochemical element electrodes can be obtained.

Here, in the present invention, foreign substances refer to impurities that were originally mixed in the electrode active material or binder, which are raw materials of the granulated particles, or a part of the pipe (pipe inner wall or joint part, etc.) during transport of the granulated particles, resulting in abrasion of the granulated particles. refers to those incorporated in

Here, in the present invention, the coarse particles preferably have a volume average particle diameter of 5 times or more, more preferably 4 times or more, still more preferably 3 times or more with respect to the volume average particle diameter of the obtained composite particles.

The opening diameter of the sieve 22 used when the sieve 22 separates foreign substances and/or coarse particles is preferably 1.1 to 6.0 times, more preferably 1.1 to the volume average particle diameter of the composite particles obtained. -5.0 times, More preferably, it is 1.1-4.0 times.

In addition, there is no restriction|limiting in particular as a raw material of the sieve 22 in the case of isolate|separating a foreign material and/or a coarse particle by the sieve 22. Usually, it is selected from the product made from resin, a metal, and a product made from a magnetic material.

Although there is no restriction|limiting in particular as a motion form of the sieve 22, A motion form, such as a vibration type, an in-plane motion type, an ultrasonic type, can be used. In the case of the vibrating type, it is preferable to vibrate only in the horizontal direction. The granulated particles transported by air are packed after removing foreign substances and/or coarse particles.

(Composite particles for electrochemical device electrodes)

As described above, the composite particles according to the present invention are obtained by a manufacturing method including at least a slurry preparation process, a granulation process, and a removal process.

That is, in embodiment mentioned above, although it was set as the structure which provides a conveyance process, you may abbreviate|omit a conveyance process.

(electrochemical element electrode)

An electrochemical element electrode (hereinafter, simply referred to as an "electrode") using the composite particle of the present invention is formed by laminating an electrode active material layer containing the composite particle on a current collector. As a material for current collectors used for an electrode, a metal, carbon, a conductive polymer etc. are mentioned, for example, A metal is mentioned as a suitable material. As a metal for electrical power collectors, aluminum, platinum, nickel, a tantalum, titanium, stainless steel, copper, another alloy, etc. are mentioned normally. The current collector is in the form of a film or a sheet, and the thickness thereof is arbitrarily selected according to the purpose of use, but is preferably 1 to 200 μm, more preferably 5 to 100 μm, further preferably 10 to 50 μm.

The electrode active material layer may be formed by molding an electrode material containing composite particles into a sheet shape, and then laminating it on a current collector. It is preferable to form an active material layer by directly molding an electrode material containing composite particles on the current collector . As a method of forming an electrode active material layer made of an electrode material, there are a dry molding method such as a pressure molding method, and a wet molding method such as a coating method. A dry molding method that facilitates uniformly molding a thick active material layer is preferable.

As the dry molding method, there are a pressure molding method, an extrusion molding method (also referred to as paste extrusion), and the like. The pressure forming method is a method of forming the electrode active material layer by applying pressure to the electrode material to densify the electrode material by rearrangement and deformation. Extrusion molding is a method of extruding an electrode material into a film, sheet, etc. by extruding it with an extrusion molding machine, and is a method capable of continuously molding an electrode active material layer into a long product. Among these, it is preferable to use the pressure molding method from the point which can carry out with simple installation. As the pressure forming method, for example, a roll pressure forming method in which an electrode material containing composite particles is supplied to a roll pressure forming apparatus with a supply device such as a screw feeder to form an electrode active material layer, or an electrode material is applied onto a current collector and a method of dispersing the electrode material to a blade or the like to adjust the thickness, followed by molding with a pressurizing device, a method of filling the mold with the electrode material, and pressurizing the mold for molding.

Among these pressure forming methods, the roll pressure forming method is suitable. In this method, you may laminate|stack an electrode active material layer directly on an electrical power collector by sending an electrical power collector to a roll simultaneously with supply of an electrode material. From the viewpoint of making the adhesion between the electrode active material layer and the current collector sufficient, the temperature at the time of molding is preferably 0 to 200 ° C. desirable. In the roll pressure forming method, from the viewpoint of improving the uniformity of the thickness of the electrode active material layer, the forming speed is preferably 0.1 to 40 m/min, more preferably 1 to 40 m/min. Further, the line pressure between the rolls is preferably 0.2 to 30 kN/cm, and more preferably 0.5 to 10 kN/cm.

In order to eliminate the dispersion|variation in the thickness of the shape|molded electrode, and to increase the density of an electrode active material layer and to aim at high capacity|capacitance, you may perform post-pressurization further as needed. As for the method of post-pressurization, the press process with a roll is common. In the roll press process, two cylindrical rolls are arranged up and down in parallel at a narrow space|interval, and each is rotated in the opposite direction, and an electrode is rolled in between and pressurized. In addition, you may use a roll, heating or cooling, etc. temperature-controlling.

(electrochemical element)

The electrochemical element uses the electrochemical element electrode obtained by making it above for at least one of a positive electrode and a negative electrode, and is further equipped with a separator and electrolyte solution. As an electrochemical element, a lithium ion secondary battery, a lithium ion capacitor, etc. are mentioned, for example. Hereinafter, the case where an electrochemical element is a lithium ion secondary battery is demonstrated.

(separator)

As a separator, For example, the microporous film or nonwoven fabric which consists of polyolefin resin, such as polyethylene and a polypropylene, and an aromatic polyamide resin; a porous resin coat containing inorganic ceramic powder; etc. can be used. The thickness of the separator is preferably 0.5 to 40 µm from the viewpoint of workability in manufacturing a lithium ion battery.

(electrolyte)

As electrolyte solution for lithium ion secondary batteries, the nonaqueous electrolyte solution which melt|dissolved the supporting electrolyte in the nonaqueous solvent is used, for example. 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, (C ₂ F ₅ SO ₂ )NLi, and the like. _{Among them, LiPF 6} , LiClO ₄ , and CF ₃ SO ₃ Li which are easily soluble in a solvent and exhibit a high degree of dissociation are preferable. These may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Since the lithium ion conductivity increases as the supporting electrolyte having a high degree of dissociation is used, the lithium ion conductivity may be adjusted according to the type of the supporting electrolyte.

It is preferable to use the density|concentration of the supporting electrolyte in electrolyte solution at the density|concentration of 0.5-2.5 mol/L according to the kind of supporting electrolyte. Even if the density|concentration of a supporting electrolyte is too low or too high, ionic conductivity may fall.

The nonaqueous 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 methylethyl carbonate (MEC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide; An ionic liquid used also as a supporting electrolyte, etc. are mentioned. Among them, carbonates are preferable because of their high dielectric constant and a wide stable potential region. A nonaqueous solvent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. In general, the lower the viscosity of the non-aqueous solvent, the higher the lithium ion conductivity, and the higher the dielectric constant, the higher the solubility of the supporting electrolyte. good to use In addition, as a non-aqueous solvent, what replaced all or part of hydrogen with fluorine may be used together or in whole quantity.

Moreover, you may make the electrolyte solution contain an additive. As an additive, For example, carbonate types, such as vinylene carbonate (VC); sulfur-containing compounds such as ethylene sulfite (ES); and fluorine-containing compounds such as fluoroethylene carbonate (FEC). An additive may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

Moreover, as a substitute for the said electrolyte solution, For example, Polymer electrolytes, such as polyethylene oxide and polyacrylonitrile; a gel polymer electrolyte in which the polymer electrolyte is impregnated with an electrolyte; inorganic solid electrolytes such as LiI and Li _{3 N;} You may use the back.

An electrochemical element is obtained by making said electrode and separator impregnate with electrolyte solution. Specifically, it can be manufactured by winding, laminating, or folding the above electrodes and separators as necessary, placing them in a container, and injecting an electrolyte into the container to seal. Moreover, you may accommodate in the container what made the said electrode and the separator previously impregnated with electrolyte solution. As a container, any well-known thing, such as a coin shape, a cylinder shape, and a square shape, can be used.

According to the manufacturing method of the composite particle for electrochemical element electrodes which concerns on this embodiment, also in the case of mass production, the composite particle which suppressed the broadening of the particle size distribution can be obtained.

Example

Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited in any way by these Examples. In addition, parts and % in a present Example are based on weight unless otherwise stated.

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

<Particle Size Distribution of Composite Particles>

It measured by the dry method using Microtrac (made by Nikkiso). The results are shown in Table 1.

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

B: The particle size distribution is slightly sharp (the ratio of the half width to the length of the peak base is 0.25 or more and less than 0.35)

C: The particle size distribution is slightly broad (the ratio of the half width to the length of the peak base is 0.35 or more and less than 0.50)

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

<Long dry formability>

The composite particles obtained in Examples and Comparative Examples were roll-formed on edged foil, and long formability was confirmed. The results are shown in Table 1.

A: Can be molded without defects over 10 m

B: 10 m can be molded, but defects are visible

C: It is not possible to mold 5 m due to poor fluidity.

D: It is not possible to mold 1 m due to poor fluidity

<Cycle characteristics>

After the produced lithium ion secondary battery was left still for 24 hours, it was charged to 4.2 V at a charge/discharge rate of 0.1 C, and then charge/discharge was performed to discharge to 3.0 V, and the initial capacity C0 was measured. In addition, charging and discharging were repeated in the environment of the temperature of 25 degreeC, and the capacity|capacitance C2 after 100 cycles was measured. Then, the capacity retention rate ΔC expressed by ΔC = (C2/C0) × 100 (%) was calculated. It shows that it is excellent in cycling characteristics, so that the value of this capacity|capacitance retention rate (DELTA)C is high. The results are shown in Table 1.

A: Over 90% capacity retention

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

C: Capacity retention rate less than 80%

D: Measurable

[Example 1]

(Preparation of carboxycellulose solution as viscosity modifier)

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

(Production of slurry for negative electrode)

100 parts of artificial graphite having an average particle diameter of 24.5 μm as an electrode active material for a negative electrode through the raw material input tube 8 into the slurry tank 6 (see FIG. 1) (for example, a planetary mixer equipped with a disper), 100 parts of 1% aqueous solution of CMC was added to this, and after adjusting the solid content concentration to 53.5 weight% with ion-exchange water, it stirred by the stirring blade 10 and it mixed at 25 degreeC for 60 minutes. Next, after adjusting the solid content concentration to 40% by weight with ion-exchanged water, the mixture was further mixed at 25°C for 15 minutes. Next, as a binder, SBR latex (BM-400B (manufactured by Nippon Zeon)) is adjusted to a solid content concentration of 40% by weight, and 2.9 parts of the one after storage for 90 days at room temperature is added, followed by stirring with a stirring blade 10. Mix for 10 minutes. This was subjected to a defoaming treatment under reduced pressure to obtain a slurry for a negative electrode with good luster and fluidity (final solid content concentration of 40% by weight).

(granulation of granulated particles for negative electrode)

The slurry obtained above is rotated using a granulating apparatus 14 (refer to FIG. 1) (specifically, a spray dryer (manufactured by Okawara Chemical Co., Ltd.)) and a rotary disk 18 having a diameter of 85 mm. Spray-drying granulation was performed on the conditions of 25,000 rpm, a dry air temperature of 180 degreeC, and the temperature of 90 degreeC of particle collection outlet, and the granulated particle for negative electrodes was obtained by cyclone collection|recovery. The obtained granulated particles 12 had a volume average particle diameter of 70 µm. On the other hand, the flow velocity of the dry air was controlled to 20 m/s by setting the cyclone differential pressure in the drying furnace 16 of the granulating apparatus 14 to 1 kpa.

(Transfer and removal process of granulated particles for negative electrode)

The obtained granulated particles for negative electrode are transported to a vibrating sieve facility by air, a sieve 22 of 130 μm is installed in a transverse vibration type vibrating sieve, and the coarse particles are removed by filtering the coarse particles for negative electrode through a sieve. Composite particles were obtained. In the transfer step of the granulated particles to the vibrating sieve facility, the granulated particles were transferred by flowing air through the pipe 20 . By setting the flow air amount to 0.5 Nm ³ /min, the flow rate of the flowing air was controlled to 5 m/s and the high ratio to 30 (granulated particles (kg/h)/air (kg/h)), respectively.

(Packing process of composite particle for negative electrodes)

The obtained composite particle for negative electrodes was cut out with the rotary valve, and was packaged in the bag made from polyethylene.

(Manufacture of negative electrode for lithium ion secondary battery)

Next, the obtained composite particles for negative electrodes were placed on a roll (roll temperature 100° C., press line pressure 4.0 kN/cm) of a roll press machine (pressure cut roughening hot roll, manufactured by Hirano Kiken Kogyo Co., Ltd.), and an electrolytic copper foil as a current collector (thickness: 20) 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.

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

_{To 92 parts of LiCoO 2} as a positive electrode active material (hereinafter, may be abbreviated as "LCO"), polyvinylidene fluoride (PVDF; "KF-1100" manufactured by Kureha Chemical Co., Ltd.) as a positive electrode binder is added so that the solid content is 2 parts, Furthermore, 6 parts of acetylene black ("HS-100" by Denki Chemical Industry Co., Ltd.) and 20 parts of N-methyl- 2-pyrrolidone were added, it mixed with the planetary mixer, and the slurry for positive electrodes was obtained. This slurry for positive electrodes was apply|coated to 18-micrometer-thick aluminum foil, and after drying at 120 degreeC for 30 minutes, it roll-pressed and obtained the 60-micrometer-thick positive electrode for lithium ion secondary batteries.

(Preparation of separator)

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

(Manufacture of lithium ion secondary battery)

As an exterior of the battery, an aluminum packaging material exterior was prepared. The positive electrode for lithium ion secondary batteries obtained above ^{was cut out in the square of 4x4 cm<2>} , and it arrange|positioned so that the surface by the side of an electrical power collector may contact|connect the aluminum packaging material exterior. The square separator obtained above was arrange|positioned on the surface of the positive electrode active material layer of the positive electrode for lithium ion secondary batteries. Moreover, the negative electrode for lithium ion secondary batteries obtained above ^{was cut out in the square of 4.2x4.2 cm<2>} , and it arrange|positioned on the separator so that the surface by the side of a negative electrode active material layer may face a separator. _{Further, a LiPF 6} solution having a concentration of 1.0 M containing 2.0% of vinylene carbonate was filled. The solvent of this LiPF ₆ solution is a mixed solvent of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) (EC/EMC = 3/7 (volume ratio)). Further, 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 (laminate type cell) was manufactured.

[Example 2]

(Preparation of carboxycellulose solution as viscosity modifier)

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

(Production 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 Chemical Industry Co., Ltd.) as carbon fine particles in the slurry tank 6 (see Fig. 1) (for example, a planetary mixer equipped with a disper) It injected|threw-in and dry blended for 10 minutes. Then, 1.0 part of the 1% aqueous solution of carboxymethylcellulose prepared above in terms of solid content was added. Next, ion-exchange water was added until it became 85 weight% of solid content, and it knead|mixed at 30 degreeC for 30 minutes by stirring with the stirring blade 10. As a binder, 1 part of a conjugated diene-based latex having a solid content of 40% (BM-600B (manufactured by Nippon Zeon)) in terms of solid content was added to the mixture of the positive electrode active material and carbon fine particles. After the binder was added, it was kneaded for 3 minutes by stirring with a stirring blade 10 for uniform dispersion to obtain a slurry for a positive electrode (final solid content concentration of 85% by weight).

(granulation of granulated particles for positive electrode)

The slurry obtained above is rotated using a granulating apparatus 14 (refer to FIG. 1) (specifically, a spray dryer (manufactured by Okawara Chemical Co., Ltd.)) and a rotary disk 18 having a diameter of 85 mm. Spray-drying granulation was performed under the conditions of 25,000 rpm, a dry air temperature of 180 degreeC, and the temperature of 90 degreeC of particle collection outlet, and the granulated particle for positive electrodes was obtained by cyclone collection|recovery. The obtained granulated particles 12 had a volume average particle diameter of 40 µm. On the other hand, the flow velocity of the dry air was controlled to 20 m/s by setting the cyclone differential pressure in the drying furnace 16 of the granulating apparatus 14 to 1 kpa.

(Transfer and removal process of granulated particles for positive electrode)

The obtained granulated particles for positive electrode are transported by air to a vibrating sieve equipment, a sieve 22 of 130 μm is installed in a transverse vibration type vibrating sieve, and the coarse particles for positive electrode are filtered through a sieve to remove coarse particles, for positive electrode Composite particles were obtained. In the transfer step of the granulated particles to the vibrating sieve facility, the granulated particles were transferred by flowing air through the pipe 20 . By setting the flow air amount to 0.5 Nm ³ /min, the flow rate of the flowing air was controlled to 5 m/s and the high ratio to 30 (granulated particles (kg/h)/air (kg/h)), respectively.

(Packing process of composite particle for positive electrode)

The obtained composite particle|grains for positive electrodes were cut out with the rotary valve, and it packed in the bag made from polyethylene.

(Production of positive electrode for lithium ion secondary battery)

The composite particle for positive electrode obtained above is used for a fixed-quantity feeder ("Nikka Spray KV" manufactured by Nikka Corporation), and a press roll (roll temperature 100°C, press) of a roll press machine ("Pressure cutting rough surface hot roll" manufactured by Hirano Kiken Kogyo) A linear pressure of 500 kN/m) was supplied. An aluminum foil having a thickness of 20 µm is inserted between the press rolls, and the composite particles for positive electrode supplied from a quantitative feeder are adhered on an aluminum foil (current collector) and press-molded at a molding speed of 1.5 m/min, the positive electrode A positive electrode having an active material layer was obtained.

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

As a negative electrode active material, artificial graphite (average particle diameter: 24.5 μm, graphite interlayer distance (interplanar spacing (d value) of (002) plane by X-ray diffraction method (d value): 0.354 nm)) 96 parts, 1.5% aqueous solution of carboxymethylcellulose (DN- 800H: Daicel Chemical Industry Co., Ltd.) was mixed with 1.0 part in terms of solid content, and ion-exchanged water was added so that the solid content concentration was 55%, and mixed and dispersed.Then, styrene-butadiene copolymer latex (BM-400B) was added In terms of solid content, 3.0 parts were mixed to obtain a negative electrode slurry having a final solid content concentration of 50%.This negative electrode slurry was applied to 18 μm thick copper foil, dried at 120° C. for 30 minutes, and then roll pressed to a thickness of 50 A negative electrode of μm was obtained.

(Preparation of separator)

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

(Manufacture of lithium ion secondary battery)

As an exterior of the battery, an aluminum packaging material exterior was prepared. The positive electrode for lithium ion secondary batteries obtained above ^{was cut out in the square of 4x4cm<2>} , and it arrange|positioned so that the surface by the side of an electrical power collector may contact|connect the aluminum packaging material exterior. The square separator obtained above was arrange|positioned on the surface of the positive electrode active material layer of the positive electrode for lithium ion secondary batteries. Moreover, the negative electrode for lithium ion secondary batteries obtained above ^{was cut out in the square of 4.2x4.2 cm<2>} , and it arrange|positioned on the separator so that the surface by the side of a negative electrode active material layer may face a separator. _{Further, a LiPF 6} solution having a concentration of 1.0 M containing 2.0% of vinylene carbonate was filled. The solvent of this LiPF ₆ solution is a mixed solvent of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) (EC/EMC = 3/7 (volume ratio)). Further, 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 (laminate type cell) was manufactured.

[Example 3]

Preparation of negative electrode slurry, granulation of negative electrode granulated particles, transfer and coarse particle removal, preparation of negative electrode for lithium ion secondary battery and lithium ion secondary battery in the same manner as in Example 1 except that the final solid content concentration was 30% by weight production was carried out.

[Example 4]

The slurry for negative electrodes was produced similarly to Example 1. Using the obtained slurry for negative electrodes, the flow rate of dry air was controlled to 15 m/s by adjusting the cyclone differential pressure of the spray dryer to 0.8 kpa, and granulated particles for negative electrodes were granulated in the same manner as in Example 1, except that the negative electrode The transfer of the granulated particles for use, the removal of the coarse particles, the production of the negative electrode for a lithium ion secondary battery, and the production of the lithium ion secondary battery were performed.

[Example 5]

The slurry for negative electrodes was produced similarly to Example 1. Using the obtained slurry for negative electrodes, the flow rate of dry air was controlled to 30 m/s by adjusting the cyclone differential pressure of the spray dryer to 1.3 kpa, and granulated particles for negative electrodes were granulated in the same manner as in Example 1, except that the negative electrode The transfer of the granulated particles for use, the removal of the coarse particles, the production of the negative electrode for a lithium ion secondary battery, and the production of the lithium ion secondary battery were performed.

[Example 6]

Similar to Example 1, preparation of the slurry for negative electrodes and granulation of the granulated particles for negative electrodes were performed. In the transfer step of granulated particles for negative electrode, by setting the flow air amount to 1.0 Nm ³ /min, the flow rate of the flowing air is 10 m/s and the high ratio is 13 (granulated particles (kg/h)/air (kg/h)) ), transfer of granulated particles for negative electrodes and removal of coarse particles, production of negative electrodes for lithium ion secondary batteries, and production of lithium ion secondary batteries were performed in the same manner as in Example 1, except that each was controlled.

[Comparative Example 1]

Preparation of negative electrode slurry, granulation of negative electrode granulated particles, transport and removal of coarse particles, production of negative electrode for lithium ion secondary battery and lithium ion secondary battery in the same manner as in Example 1, except that the final solid content concentration was 15% by weight production was carried out.

[Comparative Example 2]

Except that the final solid content concentration was 93% by weight, as in Example 2, preparation of a slurry for positive electrode, granulation of granulated particles for positive electrode, transfer and removal of coarse particles, preparation of positive electrode for lithium ion secondary battery and lithium ion secondary battery production was carried out.

[Comparative Example 3]

The slurry for negative electrodes was produced similarly to Example 1. Using the obtained slurry for negative electrodes, the flow rate of dry air was controlled to 40 m/s by setting the cyclone differential pressure of the spray dryer to 1.5 kpa, and granulated particles for negative electrodes were granulated in the same manner as in Example 1, except that the negative electrode The transfer of the granulated particles for use, the removal of the coarse particles, the production of the negative electrode for a lithium ion secondary battery, and the production of the lithium ion secondary battery were performed.

[Comparative Example 4]

The slurry for negative electrodes was produced similarly to Example 1. Using the obtained slurry for negative electrodes, the flow rate of dry air was controlled to 5 m/s by setting the cyclone differential pressure of the spray dryer to 0.5 kpa, and granulated particles for negative electrodes were granulated in the same manner as in Example 1, except that the negative electrode The transfer of the granulated particles for use, the removal of the coarse particles, the production of the negative electrode for a lithium ion secondary battery, and the production of the lithium ion secondary battery were performed.

As shown in Table 1, as a method for producing composite particles for electrochemical device electrodes, a slurry preparation step of dispersing or dissolving an electrode active material and a binder in a medium to obtain a slurry, and a granulation step of spray drying the slurry to obtain granulated particles and a removal step of removing foreign substances and/or coarse particles from the granulated 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, and spraying in the granulation step When the flow rate of dry air during drying is 10 m/s or more and less than 40 m/s, the particle size distribution and dry formability of the obtained composite particles are good, and the cycle of a lithium ion secondary battery manufactured using the obtained composite particles The properties were good.

Claims (3)

A method for producing a composite particle for an electrochemical device electrode, the method comprising:
A slurry production process of dispersing or dissolving an electrode active material and a binder in a medium to obtain a slurry;
a granulation step of spray-drying the slurry to obtain granulated particles;
a removal process of removing foreign substances and/or coarse particles from the granulated particles;
The solid content concentration of the slurry obtained in the slurry preparation process is 30% by weight or more and 90% by weight or less,
The manufacturing method of the composite particle for electrochemical element electrodes whose flow rates of the dry air at the time of the spray drying in the said granulation process are 10 m/s or more and less than 40 m/s. According to claim 1,
After the granulation process, there is provided a transport process of transporting the granulated particles with air;
The manufacturing method of the composite particle for electrochemical element electrodes whose air flow rates in the said conveyance process are 0.5 m/s or more and 20 m/s or less. 3. The method of claim 2,
In the transfer process,
The high 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 5 or more and 150 or less electrochemical A method for producing composite particles for device electrodes.

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