JP2013051203A - Composite particle for electrochemical element electrode, electrochemical element electrode material, electrochemical element electrode, and electrochemical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide composite particles for an electrochemical element electrode, having high adhesiveness to a collector and excellent moldability, and capable of providing an electrochemical element electrode having low internal resistance and excellent high-temperature cycle characteristics.SOLUTION: The composite particles for an electrochemical element electrode include an electrode active material and a particulate binder. The binder contains a nitrile group-containing monomer unit, a monomer unit having an acid functional group, and a monomer unit containing a straight-chain alkylene structure having a carbon number of 4 or higher, while the content ratio of the nitrile group-containing monomer unit is 10-50 wt.%. The binder is a copolymer having an iodine value of 3-40 mg/100 mg.

Description

  The present invention relates to composite particles for electrochemical element electrodes, electrochemical element electrode materials, electrochemical element electrodes, and electrochemical elements.

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

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

  The electrochemical element electrode is usually formed by laminating an active material layer formed by binding an electrode active material and a conductive material used as necessary with a binder on a current collector. As a method for forming such an active material layer, Patent Document 1 discloses an aqueous slurry containing electrode active material, rubber particles, and water as a dispersion medium, and particles obtained by spray drying the obtained aqueous slurry. A method of forming an electrode active material layer using the obtained electrode material is disclosed.

  However, in the technique described in Patent Document 1, the flexibility of the obtained electrode and the adhesion between the current collector and the electrode active material layer are not sufficient, and therefore battery characteristics such as internal resistance and high-temperature cycle characteristics. It was inferior to.

  Further, when the electrode active material layer is formed by a coating method as in the prior art, the binder is unevenly distributed on the surface of the electrode active material layer when the solvent is dried after coating, and the internal resistance becomes high. In particular, when a compound containing nickel is used as the positive electrode active material, the aluminum current collector is corroded, and the moldability and battery characteristics are deteriorated.

Japanese Patent No. 4219705

  The present invention provides a composite particle for an electrochemical element electrode that can provide an electrochemical element electrode having high adhesion to a current collector, excellent moldability, low internal resistance, and excellent high-temperature cycle characteristics. For the purpose. Another object of the present invention is to provide an electrochemical element electrode material, an electrochemical element electrode, and an electrochemical element obtained by using such composite particles for electrochemical element electrodes.

  As a result of diligent research to achieve the above object, the present inventors have found that the composite particles containing the electrode active material and the predetermined particulate binder have high adhesion to the current collector, excellent moldability, and When the electrode is used, the inventors have found that the internal resistance is low and the high temperature cycle characteristics can be improved, and the present invention has been completed.

That is, according to the present invention, an electrode active material and a particulate binder are included, and the binder includes a nitrile group-containing monomer unit, a monomer unit having an acidic functional group, and a carbon number of 4 or more. Electricity comprising a linear alkylene structure-containing monomer unit, a content ratio of the nitrile group-containing monomer unit of 10 to 50% by weight, and an iodine value of 3 to 40 mg / 100 mg Composite particles for chemical element electrodes are provided.
In the composite particle for an electrochemical element electrode of the present invention, the acidic functional group is preferably at least one selected from a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group.

According to the present invention, there is provided an electrochemical element electrode material comprising any one of the above-described composite particles for an electrochemical element electrode.
In addition, according to the present invention, there is provided an electrochemical element electrode characterized in that an active material layer formed from the above electrochemical element electrode material is laminated on a current collector.
The electrochemical element electrode of the present invention is preferably formed by laminating the active material layer on the current collector by pressure molding, and by laminating by roll pressure molding. More preferred.
Furthermore, according to the present invention, there is provided a method for producing any one of the above-described composite particles for an electrochemical element electrode, the step of dispersing the electrode active material and the binder in water to obtain a slurry; There is provided a method for producing composite particles for an electrochemical device electrode, comprising spray-drying and granulating.

  According to the present invention, the composite particle for an electrochemical element electrode that can provide an electrochemical element electrode having high adhesion to a current collector, excellent moldability, low internal resistance, and excellent high-temperature cycle characteristics, In addition, an electrochemical element electrode material, an electrochemical element electrode, and an electrochemical element obtained by using such composite particles for electrochemical element electrodes can be provided. In particular, according to the present invention, the electrode active material layer can be formed by powder molding the composite particles for electrochemical element electrodes of the present invention without using a dispersion medium or solvent such as water or an organic solvent. Therefore, as in the case of using a conventionally used coating method, the binder is unevenly distributed in the electrode active material layer, thereby increasing the internal resistance, and nickel as the positive electrode active material. Even when a compound containing is used, it is possible to effectively prevent the occurrence of the problem that the aluminum current collector is corroded and the moldability and battery characteristics are deteriorated.

  The composite particle for an electrochemical element electrode of the present invention comprises an electrode active material and a particulate binder, and the binder includes a nitrile group-containing monomer unit, a monomer unit having an acidic functional group, and a carbon number. Containing 4 or more linear alkylene structure-containing monomer units, the content ratio of the nitrile group-containing monomer units is 10 to 50% by weight, and the iodine value is 3 to 40 mg / 100 mg It is a combination.

(Electrode active material)
The electrode active material used in the present invention is appropriately selected depending on the type of electrochemical element. For example, as an electrode active material for a positive electrode of a lithium ion secondary battery, a compound containing a transition metal, specifically, an oxide containing a transition metal, or a composite oxide of lithium and a transition metal is used. Can do. Examples of such transition metals include cobalt, manganese, nickel, iron and the like. In the present invention, a compound containing nickel, particularly a composite oxide containing lithium and nickel is preferable. Used for. In particular, a composite oxide containing lithium and nickel is suitable because it has a higher capacity than lithium cobaltate (LiCoO ₂ ) that has been conventionally used as a positive electrode active material for lithium secondary batteries. .
Examples of the composite oxide containing lithium and nickel include those represented by the following general formula.
_{LiNi 1-x-y Co x} M y O 2
(However, 0 ≦ x <1, 0 ≦ y <1, x + y <1, M is at least one element selected from B, Mn, and Al)

  Examples of the electrode active material for the negative electrode of the lithium ion secondary battery include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), and pitch-based carbon fibers; and conductive materials such as polyacene. Functional polymer; Si, Sn, Sb, Al, Zn, W and the like that can be alloyed with lithium are included.

Alternatively, an allotrope of carbon is usually used as the electrode active material for the electric double layer capacitor. The electrode active material for an electric double layer capacitor is preferably one having a large specific surface area that can form an interface with a larger area even with the same mass. Specifically, the specific surface area of ^{30 m} 2 / g or more, preferably in the range of 500~5,000m ² / g, more preferably 1,000~3,000m ² / g. Specific examples of the allotrope of carbon include activated carbon, polyacene, carbon whisker, and graphite, and these powders or fibers can be used. Among these, activated carbon is preferable, and specific examples include phenol-based, rayon-based, acrylic-based, pitch-based, and coconut shell-based activated carbon.

  Furthermore, as the electrode active material for the lithium ion capacitor, the electrode active material for the electric double layer capacitor described above as the active material for the positive electrode, and the lithium ion secondary battery described above as the active material for the negative electrode. An electrode active material for the negative electrode can be used.

(Particulate binder)
The particulate binder used in the present invention has a particle shape, a nitrile group-containing monomer unit, a monomer unit having an acidic functional group, and a linear alkylene structure-containing monomer unit having 4 or more carbon atoms Is a copolymer having a nitrile group-containing monomer unit content of 10 to 50% by weight and an iodine value of 3 to 40 mg / 100 mg.

  The particulate binder used in the present invention is not particularly limited as long as it has a particle shape. However, even in the composite particle for an electrochemical element electrode of the present invention, the particulate state is maintained, that is, the particulate state on the electrode active material. It is preferable that it can exist in the state which hold | maintained. The presence of the particle state in the composite particle for an electrochemical element electrode makes it possible to bind the electrode active materials satisfactorily without inhibiting electronic conduction. That is, the binding property between the electrode active materials can be improved without increasing the internal resistance. In the present invention, the “state in which the particle state is maintained” does not have to be a state in which the particle shape is completely maintained, and may be in a state in which the particle shape is maintained to some extent. As a result of binding, the electrode active materials may be crushed to some extent by each other.

  Examples of the nitrile group-containing monomer that forms the nitrile group-containing monomer unit constituting the particulate binder used in the present invention include acrylonitrile; α-halogenoacrylonitrile such as α-chloroacrylonitrile and α-bromoacrylonitrile; Α-alkyl acrylonitrile such as methacrylonitrile; Among these, acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is more preferable. The nitrile group-containing monomer may be used alone or in combination of two or more.

  The content ratio of the nitrile group-containing monomer unit in the particulate binder used in the present invention is 10 to 50% by weight, preferably 20 to 40% by weight, more preferably 30%, based on all monomer units. -40% by weight. If the content ratio of the nitrile group-containing monomer unit is too small, the dispersibility of the electrode active material when slurried will be reduced, resulting in inferior moldability, thereby reducing the high temperature cycle characteristics when used as an electrode. Resulting in. On the other hand, when too much, the swelling property with respect to the electrolyte solution of a particulate binder will become high, and when this is used as an electrode, high temperature cycling characteristics will fall.

  Further, the monomer having an acidic functional group forming the monomer unit having an acidic functional group constituting the particulate binder used in the present invention may be any monomer having an acidic functional group. Although not limited, in the present invention, the acidic functional group is preferably at least one selected from a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, and a monomer having a phosphoric acid group. At least one selected from a monomer having an acid group and a monomer having a sulfonic acid group is preferred, and a monomer having a carboxylic acid group is more preferred.

  Specific examples of the monomer having a carboxylic acid group include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, and β-trans-aryloxyacrylic. Derivatives of monocarboxylic acids such as acids, α-chloro-β-E-methoxyacrylic acid, β-diaminoacrylic acid; dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid; maleic anhydride, acrylic anhydride, methyl Dicarboxylic acid anhydrides such as maleic anhydride and dimethylmaleic anhydride; methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, diphenylmaleate, nonylmaleate, maleate Decyl acid, dodecyl maleate, octane maleate And derivatives of dicarboxylic acids such as decyl and fluoroalkyl maleate. These may be used alone or in combination of two or more. Among these, methacrylic acid and maleic acid are preferable, and methacrylic acid is more preferable.

  Specific examples of the monomer having a sulfonic acid group include sulfonic acid group-containing monomers such as vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, sulfoethyl methacrylate, sulfopropyl methacrylate, and sulfobutyl methacrylate. A sulfonic acid group-containing compound having no functional group other than an acid group; a compound containing an amide group and a sulfonic acid group such as 2-acrylamido-2-methylpropanesulfonic acid (AMPS); 3-allyloxy-2-hydroxy And compounds containing a hydroxyl group and a sulfonic acid group, such as propanesulfonic acid (HAPS). These lithium salts, sodium salts, potassium salts, and the like can also be used. These may be used alone or in combination of two or more. Among these, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is preferable.

  Specific examples of the monomer having a phosphoric acid group include: 2-acryloyloxyethyl phosphate, 2-methacryloyloxyethyl phosphate, methyl-2-acryloyloxyethyl phosphate, methyl-2-methacryloyloxy phosphate Examples thereof include ethyl, ethyl phosphate-acryloyloxyethyl phosphate, and ethyl phosphate-methacryloyloxyethyl. These may be used alone or in combination of two or more. Among these, 2-methacryloyloxyethyl phosphate is preferable.

  The content ratio of the monomer unit having an acidic functional group in the particulate binder used in the present invention is preferably 1 to 30% by weight, more preferably 1 to 20% by weight, based on all monomer units. More preferably, it is 1 to 15% by weight. By setting the content ratio of the monomer unit having an acidic functional group in the above range, it is possible to improve the adhesion with the current collector while maintaining the flexibility of the electrode.

  In addition, examples of the monomer that forms the linear alkylene structure-containing monomer unit having 4 or more carbon atoms that constitute the particulate binder used in the present invention include, for example, conjugated diene monomers having 4 or more carbon atoms. Specific examples of the conjugated diene monomer having 4 or more carbon atoms include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, chloroprene and the like. . In addition, the conjugated diene monomer is included in a state having a double bond after the copolymerization. However, by hydrogenating the double bond, a linear alkylene structure is formed in the copolymer. Containing monomer units can be formed.

  In the particulate binder used in the present invention, the content ratio of the linear alkylene structure-containing monomer unit having 4 or more carbon atoms is preferably 50 to 90% by weight, more preferably, based on the total monomer units. Is 50 to 75% by weight, more preferably 50 to 65% by weight. By setting the content ratio of the linear alkylene structure-containing monomer unit having 4 or more carbon atoms within the above range, it is possible to impart appropriate flexibility to the electrode and improve the moldability of the electrode.

  Further, the particulate binder used in the present invention may contain other monomer units in addition to the above monomer units. Examples of other monomer units include polymerized units derived from other vinyl monomers. Examples of such other vinyl monomers include two or more carbons such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate. -Carboxylic acid esters having a carbon double bond; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate; methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether Vinyl ethers such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, isopropenyl vinyl ketone and the like; heterocyclic ring-containing vinylation such as N-vinyl pyrrolidone, vinyl pyridine and vinyl imidazole Compound;

  The particulate binder used in the present invention has an iodine value of 3 to 40 mg / 100 mg, preferably 3 to 20 mg / 100 mg, more preferably 3 to 10 mg / 100 mg. If the iodine value is too high, chemical stability against a high potential is lowered, and as a result, the high-temperature cycle characteristics may be lowered. On the other hand, if the iodine value is too low, the crystallinity of the particulate binder is high. As a result, the moldability may be reduced. The iodine value is determined according to JIS K 6235 (2006).

  In addition, although the particulate binder used by this invention has a particle shape, it is normally used in the state of the dispersion liquid disperse | distributed particulately in water. When dispersed in water in the form of particles, the average particle size (dispersed particle size) of the particulate binder body is preferably 80 to 500 nm, more preferably 80 to 400 nm, and even more preferably 80 to 300 nm. When the average particle diameter of the particulate binder is within this range, the strength and flexibility of the obtained electrochemical element electrode are improved.

  The glass transition temperature (Tg) of the particulate binder used in the present invention is preferably −60 to 20 ° C., more preferably −55 to 10 ° C., and particularly preferably −50 to 0 ° C. When the glass transition temperature is in the above range, the obtained electrochemical device electrode can have excellent strength and flexibility and high output characteristics.

  The method for producing the particulate binder used in the present invention is not particularly limited, but the above-described monomers are polymerized by an emulsion polymerization method using water as a dispersion medium, and the obtained copolymer is dispersed in water. It can be produced by hydrogenation (hydrogenation reaction) as it is.

  The emulsifier used in the emulsion polymerization is not particularly limited, and any of an anionic surfactant, a nonionic surfactant, and a cationic surfactant can be used. The amount of the emulsifier can be arbitrarily set, and is usually about 0.01 to 10 parts by weight with respect to 100 parts by weight of the total amount of monomers used for polymerization.

  Examples of the polymerization initiator used for the polymerization include lauroyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, 3,3,5-trimethylhexanoylper Organic peroxides such as oxide, azo compounds such as α, α′-azobisisobutyronitrile, ammonium persulfate, potassium persulfate and the like can be mentioned.

  And in this invention, a particulate-form binder can be obtained by hydrogenating the copolymer obtained by emulsion polymerization in the state disperse | distributed to water. In particular, in the present invention, the particulate binder is obtained in the form of a dispersion dispersed in the form of particles in water by hydrogenation while the copolymer obtained by emulsion polymerization is dispersed in water. As a result, the particulate binder can be present in a state in which the particulate state is maintained in the composite particle for an electrochemical element electrode of the present invention. In addition, the method of hydrogenation is not specifically limited, What is necessary is just to employ | adopt a well-known method.

  The content ratio of the particulate binder in the composite particle for an electrochemical element electrode of the present invention is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. Parts, more preferably 1 to 10 parts by weight. When the content ratio of the particulate binder is within the above range, when the electrode is used, the binding force between the electrode active materials and the adhesion force between the electrode active material layer and the current collector are ensured while sufficiently ensuring ionic conduction. It can be sufficient.

(Conductive material)
The composite particle for an electrochemical element electrode of the present invention may contain a conductive material, if necessary, in addition to the above components.

  The conductive material is not particularly limited as long as it is a particulate material having conductivity. For example, conductive carbon black such as furnace black, acetylene black, and ketjen black; graphite such as natural graphite and artificial graphite And carbon fibers such as polyacrylonitrile-based carbon fibers, pitch-based carbon fibers, and vapor-grown carbon fibers. The average particle diameter of the conductive material is not particularly limited, but is preferably smaller than the average particle diameter of the electrode active material, usually 0.001 to 10 μm, more preferably 0.05 to 5 μm, and still more preferably 0.01. It is in the range of ˜1 μm. When the average particle diameter of the conductive material is in the above range, sufficient conductivity can be expressed with a smaller amount of use.

  The content ratio of the conductive material in the composite particle for an electrochemical element electrode of the present invention is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 15 parts by weight with respect to 100 parts by weight of the electrode active material. More preferably, it is 1 to 10 parts by weight. By setting the content ratio of the conductive material in the above range, the internal resistance can be sufficiently reduced while keeping the capacity of the obtained electrochemical element high.

(Dispersant)
Moreover, in addition to each said component, the composite particle for electrochemical element electrodes of this invention may contain the dispersing agent as needed. The dispersant is a component having an action of uniformly dispersing each component in the solvent when each component constituting the composite particle for an electrochemical element electrode of the present invention is dispersed or dissolved in a solvent to form a slurry. is there. Examples of the dispersant include cellulosic polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose, and hydroxypropylcellulose, and ammonium salts or alkali metal salts thereof; poly (meth) acrylates such as sodium poly (meth) acrylate; Examples include polyvinyl alcohol, modified polyvinyl alcohol, polyethylene oxide; polyvinyl pyrrolidone, polycarboxylic acid, oxidized starch, phosphate starch, casein, various modified starches, chitin, and chitosan derivatives. These dispersants can be used alone or in combination of two or more. Among these, a cellulose polymer is preferable, and carboxymethyl cellulose, an ammonium salt or an alkali metal salt thereof is particularly preferable.

  The content ratio of the dispersant in the composite particle for an electrochemical element electrode of the present invention is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. More preferably, it is 0.8 to 2 parts by weight. By making the content rate of a dispersing agent into the said range, each component in a slurry can be disperse | distributed favorably.

(Composite particles for electrochemical device electrodes)
The composite particle of the present invention comprises an electrode active material, a particulate binder, and a conductive material and a dispersant that are added as necessary, but each of the above does not exist as an independent particle. Of these components, at least two components, preferably all components, form one particle.

  Specifically, a plurality of individual particles of each component are combined to form secondary particles, and a plurality (preferably several to several tens) of electrode active materials are bound by a particulate binder. Those that are attached to form massive particles are preferred.

  Further, the shape and structure of the composite particle are not particularly limited, but from the viewpoint of fluidity, the shape is preferably nearly spherical, and the structure is such that the particulate binder is not unevenly distributed on the surface of the composite particle. A structure that is uniformly dispersed therein is preferred.

  The method for producing the composite particle for electrochemical element electrode of the present invention is not particularly limited, but according to the spray drying granulation method described below, the composite particle for electrochemical element electrode of the present invention can be obtained relatively easily. This is preferable. Hereinafter, the spray drying granulation method will be described.

  First, a slurry for composite particles containing an electrode active material, a particulate binder, and a conductive material and a dispersant added as necessary is prepared. The slurry for composite particles can be prepared by dispersing or dissolving an electrode active material, a particulate binder, and a conductive material and a dispersant added as necessary in a solvent. In this case, when the particulate binder is dispersed in water as a dispersion medium, it can be added in a state dispersed in water. Further, when the dispersant is in a state dissolved in water, it can be added in a state dissolved in water.

  As the solvent used for obtaining the composite particle slurry, water is usually used, but a mixed solvent of water and an organic solvent may be used. Examples of the organic solvent that can be used in this case include alkyl alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol; alkyl ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, dioxane and diglyme; diethylformamide; Amides such as dimethylacetamide, N-methyl-2-pyrrolidone and dimethylimidazolidinone; sulfur solvents such as dimethylsulfoxide and sulfolane; and the like. Among these, alcohols are preferable. By using water and an organic solvent having a lower boiling point than water, the drying rate can be increased during spray drying.

  The amount of the solvent used when preparing the slurry for composite particles is such that the solid content concentration in the slurry for composite particles is preferably 1 to 50% by weight, more preferably 5 to 50% by weight, and still more preferably 10 to 30%. The amount is in the range of% by weight. By setting the solid content concentration in the above range, the particulate binder can be uniformly dispersed, which is preferable.

  The viscosity of the composite particle slurry is preferably in the range of 10 to 3,000 mPa · s, more preferably 30 to 1,500 mPa · s, and still more preferably 50 to 1,000 mPa · s at room temperature. When the viscosity of the slurry for composite particles is within this range, the productivity of the spray drying granulation step can be increased.

  Moreover, in this invention, when preparing the slurry for composite particles, you may add surfactant as needed.

  Examples of the surfactant include amphoteric surfactants such as anionic, cationic, nonionic, and nonionic anions, and anionic or nonionic surfactants that are easily thermally decomposed are preferable. The compounding amount of the surfactant is preferably 50 parts by weight or less, more preferably 0.1 to 10 parts by weight, and further preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the electrode active material. .

  The method or order of dispersing or dissolving the electrode active material, the particulate binder, and the conductive material and dispersant added as necessary in the solvent is not particularly limited. Moreover, as a mixing apparatus, a ball mill, a sand mill, a bead mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a homomixer, a planetary mixer, etc. can be used, for example. Mixing is usually performed in the range of room temperature to 80 ° C. for 10 minutes to several hours.

  Subsequently, the obtained slurry for composite particles is granulated by spray drying. Spray drying is a method of spraying and drying a slurry in hot air. An atomizer is used as an apparatus used for spraying slurry. There are two types of atomizers: a rotating disk system and a pressurizing system. In the rotating disk system, slurry is introduced almost at the center of a disk that rotates at high speed, and the slurry is removed from the disk by the centrifugal force of the disk. In this case, the slurry is atomized. In the rotating disk system, the rotational speed of the disk depends on the size of the disk, but is usually 5,000 to 30,000 rpm, preferably 15,000 to 30,000 rpm. The lower the rotational speed of the disk, the larger the spray droplets and the larger the average particle diameter of the resulting composite particles for electrochemical device electrodes. Examples of the rotating disk type atomizer include a pin type and a vane type, and a pin type atomizer is preferable. A pin-type atomizer is a type of centrifugal spraying device that uses a spraying plate, and the spraying plate has a plurality of spraying rollers removably mounted on a concentric circle along its periphery between upper and lower mounting disks. It consists of The slurry for composite particles is introduced from the center of the spray disk, adheres to the spray roller by centrifugal force, moves outward on the roller surface, and finally sprays away from the roller surface. On the other hand, the pressurization method is a method in which the slurry for composite particles is pressurized and sprayed from a nozzle to be dried.

  The temperature of the slurry for composite particles to be sprayed is usually room temperature, but may be higher than room temperature by heating. Moreover, the hot air temperature at the time of spray-drying is 80-250 degreeC normally, Preferably it is 100-200 degreeC. In the spray drying method, the method of blowing hot air is not particularly limited. For example, the method in which the hot air and the spraying direction flow side by side, the method in which the hot air is sprayed at the top of the drying tower and descends with the hot air, and the sprayed droplets and hot air flow countercurrently. Examples include a contact method, and a method in which sprayed droplets first flow in parallel with hot air, then drop by gravity and contact countercurrent.

  In addition, as a spraying method, in addition to the method of spraying the slurry for composite particles containing the electrode active material, the particulate binder, and the additive added as necessary, the particulate binder, and if necessary A method of spraying the slurry containing the additive added accordingly to the flowing electrode active material can also be used. From the standpoint of ease of particle size control, productivity, and reduction in particle size distribution, an optimal method may be appropriately selected according to the components of the composite particles.

  The average particle diameter of the composite particle for an electrochemical element electrode of the present invention thus obtained is preferably 0.1 to 1,000 μm, more preferably 1 to 80 μm, still more preferably 10 to 70 μm. By setting the average particle diameter in the above range, the fluidity of the composite particles for electrochemical element electrodes can be further improved. In addition, the average particle diameter of the composite particle for electrochemical element electrodes is a volume average particle diameter calculated by measuring with a laser diffraction particle size distribution analyzer (for example, SALD-3100; manufactured by Shimadzu Corporation).

(Electrochemical element electrode material)
The electrochemical element electrode material of the present invention comprises the above-described composite particle for an electrochemical element electrode of the present invention. The composite particle for an electrochemical element electrode of the present invention is used as an electrochemical element electrode material by including other binders or other additives alone or as necessary. The content of the composite particle for an electrochemical element electrode contained in the electrochemical element electrode material is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 90% by weight or more.

  As another binder used as needed, the particulate binder contained in the composite particle for electrochemical element electrodes of the present invention described above can be used, for example. Since the composite particle for an electrochemical element electrode of the present invention already contains a particulate binder as a binder, it is necessary to add another binder separately when preparing the electrochemical element electrode material. However, other binders may be added to further increase the binding force between the composite particles for electrochemical element electrodes. In addition, when the other binder is added, the addition amount of the other binder is the total with the particulate binder in the composite particle for an electrochemical element electrode, with respect to 100 parts by weight of the electrode active material, Preferably it is 0.01-10 weight part, More preferably, it is 0.1-5 weight part. Other additives include molding aids such as water and alcohol, and these can be added by appropriately selecting an amount that does not impair the effects of the present invention.

(Electrochemical element electrode)
The electrochemical element electrode of the present invention is formed by laminating an active material layer made of the above-described electrochemical element electrode material of the present invention on a current collector. As the current collector material, for example, metal, carbon, conductive polymer and the like can be used, and metal is preferably used. As the metal, copper, aluminum, platinum, nickel, tantalum, titanium, stainless steel, other alloys and the like are usually used. Among these, it is preferable to use copper, aluminum, or an aluminum alloy in terms of conductivity and voltage resistance. In addition, when high voltage resistance is required, high-purity aluminum disclosed in JP 2001-176757 A can be suitably used. The current collector is in the form of a film or a sheet, and the thickness thereof is appropriately selected according to the purpose of use, but is usually 1 to 200 μm, preferably 5 to 100 μm, more preferably 10 to 50 μm.

  When the active material layer is laminated on the current collector, the electrochemical element electrode material as the active material layer may be formed into a sheet and then laminated on the current collector. A method in which the electrochemical element electrode material is directly pressure-molded is preferred. As pressure molding, for example, a roll-type pressure molding apparatus provided with a pair of rolls is used. While feeding a current collector with a roll, an electrochemical element electrode material is roll-type pressure molded with a supply device such as a screw feeder. By supplying to the device, roll pressure forming method for forming the active material layer on the current collector, or spraying the electrochemical element electrode material on the current collector, and using the blade etc. Then, a method of adjusting the thickness and then forming with a pressurizing apparatus, a method of filling the mold with an electrochemical element electrode material, and pressurizing the mold to form are included. Among these, the roll pressure molding method is preferable. In particular, since the composite particles for electrochemical element electrodes of the present invention have high fluidity, the high fluidity enables molding by roll press molding, thereby improving productivity. It becomes.

  The temperature at the time of roll press molding is preferably 0 to 200 ° C, and more preferably 20 ° C or higher than the glass transition temperature of the particulate binder. By adjusting the temperature at the time of roll pressing to the above range, the adhesion between the active material layer and the current collector can be made sufficient. Moreover, the press linear pressure between rolls at the time of roll press molding is preferably 0.2 to 30 kN / cm, more preferably 1.5 to 15 kN / cm. By setting the linear pressure within the above range, the uniformity of the thickness of the active material can be improved. Moreover, the molding speed at the time of roll pressure molding is preferably 0.1 to 20 m / min, more preferably 4 to 10 m / min.

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

  Since the electrochemical element electrode of the present invention thus obtained is obtained by using the above-described composite particle for an electrochemical element electrode of the present invention for the active material layer, the active material layer, the current collector, In addition, the internal resistance is low, the internal resistance is low, and the cycle characteristics are excellent. In particular, according to the present invention, the electrode active material layer can be formed by powder molding the composite particles for electrochemical element electrodes of the present invention without using a dispersion medium or solvent such as water or an organic solvent. Therefore, as in the case of using a conventionally used coating method, the binder is unevenly distributed in the electrode active material layer, thereby increasing the internal resistance, and nickel as the positive electrode active material. Even when a compound containing is used, it is possible to effectively prevent the occurrence of the problem that the aluminum current collector is corroded and the moldability and battery characteristics are deteriorated.

(Electrochemical element)
The electrochemical device of the present invention includes the electrode for an electrochemical device of the present invention. Examples of the electrochemical element include a lithium ion secondary battery, an electric double layer capacitor, and a hybrid capacitor.

  In the electrochemical device of the present invention, for example, the electrode for electrochemical device of the present invention is used as a positive electrode and / or a negative electrode, and a separator is sandwiched between the positive electrode and the negative electrode as necessary, and a predetermined electrolytic solution is enclosed. Can be obtained.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Parts and% in each example are based on weight unless otherwise specified.
In addition, the definition and evaluation method of each characteristic are as follows.

<Iodine number>
100 g of an aqueous dispersion of a particulate binder was coagulated with 1 liter of methanol and then vacuum dried at 60 ° C. for 12 hours. The iodine value of the obtained dried polymer was measured according to JIS K6235 (2006).

<Peel strength>
The positive electrodes obtained in Examples and Comparative Examples were fixed with the positive electrode active material layer surface facing up, and a cellophane tape was attached to the surface of the positive electrode active material layer, and then the cellophane tape was applied at 50 mm / min from one end of the test piece. The stress when peeled in the 180 ° direction at a speed was measured. And this measurement was performed 10 times, the average value was calculated | required, this was made into peel strength, and the following reference | standard evaluated. It can be determined that the higher the peel strength, the higher the adhesion strength in the positive electrode active material layer and the adhesion strength between the positive electrode active material layer and the current collector.
A: Peel strength is 10 N / m or more B: Peel strength is less than 10 N / m, 5 N / m or more C: Peel strength is less than 5 N / m, 1 N / m or more D: Peel strength is less than 1 N / m

<Moldability>
The positive electrodes obtained in the examples and comparative examples were cut in the width direction (TD direction) 10 cm and the length direction (MD direction) 1 m, and the cut positive electrodes were equally distributed in the TD direction at 3 points and equally in the MD direction. The film thickness was measured at a total of 15 points (= 3 points × 5 points), and the average value A and the value B farthest from the average value were obtained. Then, from the average value A and the farthest value B, thickness unevenness was calculated according to the following formula (1), and formability was evaluated according to the following criteria. It can be judged that the smaller the thickness unevenness, the better the moldability.
Unevenness of thickness (%) = (| A−B |) × 100 / A (1)
A: Thickness variation is less than 5% B: Thickness variation is 5% or more and less than 10% C: Thickness variation is 10% or more and less than 15% D: Thickness variation is 15% or more

<Internal resistance>
The coin-type lithium secondary batteries obtained in Examples and Comparative Examples were charged to 4.2 V by a constant current method at a room temperature and a charge rate of 0.1 C after standing for 24 hours after battery preparation. Thereafter, discharge was performed at a constant current of 0.1 C in an environment of −30 ° C., and the internal resistance was evaluated by measuring the voltage drop (ΔV) 10 seconds after the start of discharge. It can be determined that the smaller the value of the voltage drop 10 seconds after the start of discharge, the smaller the internal resistance and the faster charge / discharge is possible.
A: Voltage drop amount is less than 0.2V B: Voltage drop amount is 0.2V or more and less than 0.3V C: Voltage drop amount is 0.3V or more and less than 0.5V D: Voltage drop amount is 0.5V or more , Less than 0.7V E: Voltage drop is 0.7V or more

<High temperature cycle characteristics>
The coin-type lithium secondary batteries obtained in the examples and comparative examples were charged to 4.2 V by a constant current method with a charge rate of 0.2 C under the condition of a temperature of 60 ° C., and then discharged. The charge / discharge test for discharging to 3.0 V at a rate of 0.1 C was repeated 50 times. Then, the capacity retention ratio at 50 cycles, which is the ratio of the discharge capacity Cap _5th in the fifth charge / discharge test and the discharge capacity Cap _50th in the _50th charge / discharge test ((Cap _50th / Cap _5th ) × 100%), Asked. And based on the obtained 50-cycle capacity | capacitance maintenance factor, the high temperature cycling characteristic was evaluated on the following references | standards. It is preferable that the capacity retention rate at 50 cycles is higher because the deterioration at the 50th cycle when performing a cycle test at a high temperature is small and it can be determined that the high temperature cycle characteristics are excellent.
A: Capacity maintenance ratio at 50 cycles is 80% or more B: Capacity maintenance ratio at 50 cycles is 70% or more and less than 80% C: Capacity maintenance ratio at 50 cycles is 50% or more and less than 70% D: Capacity at 50 cycles Maintenance rate is 30% or more and less than 50% E: Capacity maintenance rate at 50 cycles is less than 30%

(Production Example 1: Production of particulate saturated nitrile polymer (A1))
In an autoclave equipped with a stirrer, 240 parts of ion-exchanged water, 2.5 parts of sodium alkylbenzene sulfonate, 35 parts of acrylonitrile and 5 parts of methacrylic acid were placed in this order, and the inside of the bottle was replaced with nitrogen. Then, 0.25 part of ammonium persulfate was added and polymerized at a reaction temperature of 40 ° C. to obtain an aqueous dispersion of a nitrile polymer. The polymerization conversion was 85%, and the iodine value of the nitrile polymer was 280.

  Next, the total solid content concentration of the aqueous dispersion of the nitrile polymer obtained above was adjusted to 12% by weight, and 400 ml of the aqueous dispersion of the nitrile polymer with the adjusted solid content concentration (48 g in total solid content). ) In a 1 liter autoclave equipped with a stirrer, nitrogen gas was allowed to flow for 10 minutes to remove dissolved oxygen in the nitrile polymer, and then 75 mg of palladium acetate as a hydrogenation catalyst was added in a 4-fold mol to Pd. The solution was dissolved in 180 ml of water to which nitric acid was added. Then, after the inside of the system was replaced with hydrogen gas twice, the content of the autoclave was heated to 50 ° C. while being pressurized with hydrogen gas up to 3 MPa, and the hydrogenation reaction (“first stage hydrogenation”) was performed for 6 hours. Reaction). At this time, the iodine value of the nitrile polymer was 35.

  Subsequently, the autoclave was returned to atmospheric pressure, and 25 mg of palladium acetate was added as a hydrogenation catalyst after dissolving it in 60 ml of water added with 4-fold molar nitric acid with respect to Pd. Then, after the inside of the system was replaced twice with hydrogen gas, the content of the autoclave was heated to 50 ° C. while being pressurized with hydrogen gas up to 3 MPa, and the hydrogenation reaction (“second stage hydrogenation”) was performed for 6 hours. Reaction).

Thereafter, the contents are returned to room temperature, the inside of the system is made into a nitrogen atmosphere, and then concentrated using an evaporator until the solid content concentration becomes 40%, whereby an aqueous dispersion of the particulate saturated nitrile polymer (A1). Got. The obtained particulate saturated nitrile polymer (A1) had an iodine value of 7 mg / 100 mg and an average particle size of 117 nm. Further, 100 g of an aqueous dispersion of a particulate binder was coagulated with 1 liter of methanol and vacuum-dried at 60 ° C. for 12 hours to obtain a dry polymer, and the composition of the obtained dry polymer was analyzed by NMR. However, the composition of the particulate saturated nitrile polymer (A1) was 35% acrylonitrile units, 60% butadiene units and 60% saturated butadiene units, and 5% methacrylic acid units.

(Production Example 2: Production of particulate saturated nitrile polymer (A2))
The water content of the particulate saturated nitrile polymer (A2) was the same as in Production Example 1, except that the amount of acrylonitrile was changed from 35 parts to 25 parts and the amount of butadiene was changed from 60 parts to 70 parts. A dispersion was obtained. The obtained particulate saturated nitrile polymer (A2) has an iodine value of 7 mg / 100 mg and an average particle size of 123 nm. The composition of the particulate saturated nitrile polymer (A2) is 25% acrylonitrile units and butadiene units. And 70% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 3: Production of particulate saturated nitrile polymer (A3))
Acrylonitrile content from 35 parts to 15 parts, butadiene content from 60 parts to 8 parts
An aqueous dispersion of particulate saturated nitrile polymer (A3) was obtained in the same manner as in Production Example 1 except that the content was changed to 0 part. The obtained particulate saturated nitrile polymer (A3) has an iodine value of 7 mg / 100 mg and an average particle size of 110 nm. The composition of the particulate saturated nitrile polymer (A3) is 15% acrylonitrile units, butadiene units. And 80% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 4: Production of particulate saturated nitrile polymer (A4))
Production Example except that the amount of palladium acetate used in the first stage hydrogenation reaction was changed from 75 mg to 90 mg and the amount of palladium acetate used in the second stage hydrogenation reaction was changed from 25 mg to 10 mg. In the same manner as in Example 1, an aqueous dispersion of particulate saturated nitrile polymer (A4) was obtained. The obtained particulate saturated nitrile polymer (A4) has an iodine value of 15 mg / 100 mg and an average particle size of 120 nm. The composition of the particulate saturated nitrile polymer (A4) is 35% acrylonitrile units, butadiene units. And 60% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 5: Production of particulate saturated nitrile polymer (A5))
In the first stage hydrogenation reaction, the amount of palladium acetate used was changed from 75 mg to 10 mg, and the second stage hydrogenation reaction was not performed. An aqueous dispersion of a nitrile polymer (A5) was obtained. The obtained particulate saturated nitrile polymer (A5) has an iodine value of 27 mg / 100 mg and an average particle size of 114 nm. The composition of the particulate saturated nitrile polymer (A5) is 35% acrylonitrile units, butadiene units. And 60% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 6: Production of particulate saturated nitrile polymer (A6))
An aqueous dispersion of particulate saturated nitrile polymer (A6) was obtained in the same manner as in Production Example 1 except that 5 parts of maleic acid was used instead of 5 parts of methacrylic acid. The obtained particulate saturated nitrile polymer (A6) has an iodine value of 7 mg / 100 mg and an average particle size of 120 nm. The composition of the particulate saturated nitrile polymer (A6) is 35% acrylonitrile units, butadiene units. And 60% of saturated butadiene units and 5% of maleic acid units.

(Production Example 7: Production of particulate saturated nitrile polymer (A7))
An aqueous dispersion of the particulate saturated nitrile polymer (A7) was prepared in the same manner as in Production Example 1 except that 5 parts of acrylamide-2-methylpropanesulfonic acid (AMPS) was used instead of 5 parts of methacrylic acid. Obtained. The obtained particulate saturated nitrile polymer (A7) has an iodine value of 7 mg / 100 mg and an average particle size of 122 nm. The composition of the particulate saturated nitrile polymer (A7) is 35% acrylonitrile units, butadiene units. And 60% saturated butadiene unit and 5% acrylamido-2-methylpropanesulfonic acid unit.

(Production Example 8: Production of particulate saturated nitrile polymer (A8))
An aqueous dispersion of particulate saturated nitrile polymer (A8) was obtained in the same manner as in Production Example 1 except that 5 parts of 2-methacryloyloxyethyl phosphate was used instead of 5 parts of methacrylic acid. The resulting particulate saturated nitrile polymer (A8) has an iodine value of 7 mg / 100 mg and an average particle size of 125 nm. The composition of the particulate saturated nitrile polymer (A8) is 35% acrylonitrile units, butadiene units. And 60% of saturated butadiene units and 5% of 2-methacryloyloxyethyl phosphate units.

(Production Example 9: Production of particulate saturated nitrile polymer (A9))
The water content of the particulate saturated nitrile polymer (A9) was the same as in Production Example 1, except that the amount of acrylonitrile was changed from 35 parts to 55 parts and the amount of butadiene was changed from 60 parts to 40 parts. A dispersion was obtained. The obtained particulate saturated nitrile polymer (A9) has an iodine value of 7 mg / 100 mg and an average particle size of 128 nm. The composition of the particulate saturated nitrile polymer (A9) is 55% acrylonitrile units, butadiene units. And 40% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 10: Production of particulate saturated nitrile polymer (A10))
The water content of the particulate saturated nitrile polymer (A10) was the same as in Production Example 1, except that the amount of acrylonitrile was changed from 35 parts to 2 parts and the amount of butadiene was changed from 60 parts to 93 parts. A dispersion was obtained. The obtained particulate saturated nitrile polymer (A10) has an iodine value of 7 mg / 100 mg and an average particle size of 115 nm. The composition of the particulate saturated nitrile polymer (A10) is 2% acrylonitrile units and butadiene units. And 93% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 11: Production of particulate saturated nitrile polymer (A11))
In the first stage hydrogenation reaction, the amount of palladium acetate used was changed from 75 mg to 53 mg, and the second stage hydrogenation reaction was not performed. An aqueous dispersion of a nitrile polymer (A11) was obtained. The resulting particulate saturated nitrile polymer (A11) has an iodine value of 50 mg / 100 mg and an average particle size of 120 nm. The composition of the particulate saturated nitrile polymer (A11) is 35% acrylonitrile units, butadiene units. And 60% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 12: Production of particulate saturated nitrile polymer (A12))
An aqueous dispersion of particulate saturated nitrile polymer (A12) was obtained in the same manner as in Production Example 1, except that the amount of palladium acetate used in the second stage hydrogenation reaction was changed from 25 mg to 75 mg. The obtained particulate saturated nitrile polymer (A12) has an iodine value of 1 mg / 100 mg and an average particle size of 119 nm. The composition of the particulate saturated nitrile polymer (A12) is 35% acrylonitrile units and butadiene units. And 60% of saturated butadiene units and 5% of methacrylic acid units.

(Production Example 13: Production of particulate saturated nitrile polymer (A13))
An aqueous dispersion of particulate saturated nitrile polymer (A13) was obtained in the same manner as in Production Example 1 except that the amount of butadiene was changed from 60 parts to 65 parts and methacrylic acid was not added. The obtained particulate saturated nitrile polymer (A13) has an iodine value of 7 mg / 100 mg and an average particle size of 120 nm. The composition of the particulate saturated nitrile polymer (A13) is 35% acrylonitrile units, butadiene units. And 65% of saturated butadiene units.

(Production Example 14: Production of saturated nitrile polymer (A14))
In an autoclave equipped with a stirrer, 240 parts of ion-exchanged water, 2.5 parts of sodium alkylbenzene sulfonate, 35 parts of acrylonitrile and 5 parts of methacrylic acid were placed in this order, and the inside of the bottle was replaced with nitrogen. Then, 0.25 part of ammonium persulfate was added and polymerized at a reaction temperature of 40 ° C. to obtain an aqueous dispersion of a nitrile polymer. The polymerization conversion was 85%, and the iodine value of the nitrile polymer was 280.

  Next, the aqueous dispersion of the nitrile polymer obtained above is added to an aqueous solution of magnesium sulfate in an amount of 12 parts by weight when the amount of the nitrile polymer in the aqueous dispersion is 100 parts by weight. The aqueous dispersion was solidified by stirring, and then filtered while washing with water, followed by vacuum drying at 60 ° C. for 12 hours to obtain a nitrile polymer.

Next, the nitrile polymer obtained above was dissolved in acetone so as to have a concentration of 12% by weight, and this was placed in an autoclave, and the amount of Pd metal was 1000 ppm by weight with respect to the amount of nitrile polymer. A palladium-silica catalyst was added and a hydrogenation reaction was performed at 3.0 MPa. After completion of the hydrogenation reaction, the mixture was poured into a large amount of water to coagulate, filtered and dried to obtain a saturated nitrile polymer (A14). The obtained saturated nitrile polymer (A14) was dissolved in acetone and had no particle shape. The iodine value of the saturated nitrile polymer (A14) is 7 mg / 100 mg, and the composition of the saturated nitrile polymer (A14) is 35% acrylonitrile units, 60% butadiene units and 60% saturated butadiene units, and methacrylic acid units. It was 5%.
And the obtained saturated nitrile polymer (A14) was melt | dissolved in N-methylpyrrolidone (NMP), and the N-methylpyrrolidone solution (solid content concentration 8%) of the saturated nitrile polymer (A14) was obtained. .

Example 1
Production of Composite Particle Slurry for Positive Electrode 100 parts of LiNiO ₂ as a positive electrode active material, ₂ parts of acetylene black (HS-100, manufactured by Denki Kagaku Kogyo Co.) as a conductive material, and particulate saturation obtained in Production Example 1 as a binder 2.5 parts of an aqueous dispersion of a nitrified nitrile polymer (A1) in terms of solid content, and 2 parts of a carboxymethyl cellulose aqueous solution having a degree of etherification of 0.8 as a thickener in terms of solid content, An appropriate amount of ion-exchanged water was added and mixed and dispersed by a planetary mixer to prepare a composite particle slurry for positive electrode having a solid content concentration of 20%.

Production of composite particles for positive electrode The composite particle slurry for positive electrode obtained above was sprayed using a spray dryer (made by Okawara Kako Co., Ltd.) and a rotating disk type atomizer (diameter 65 mm), and the rotational speed was 25,000 rpm. Then, spray drying granulation was performed under conditions of a hot air temperature of 150 ° C. and a particle recovery outlet temperature of 90 ° C. to obtain composite particles for a positive electrode. The average volume particle diameter of the obtained composite particles was 40 μm.

Production of positive electrode Composite particles for positive electrode obtained as described above were placed on a roll (roll temperature rough roll, manufactured by Hirano Giken Kogyo Co., Ltd.) roll (roll temperature 100 ° C., press linear pressure 4.0 kN / cm). It supplied with the aluminum foil as a collector, shape | molded on the aluminum foil as a collector at the shaping | molding speed | rate of 20 m / min, and obtained the positive electrode which has a positive electrode active material layer with a thickness of 80 micrometers.

Production of composite particle slurry for negative electrode 100 parts of artificial graphite (average particle diameter: 24.5 μm) as negative electrode active material, aqueous dispersion of particulate saturated nitrile polymer (A1) obtained in Production Example 1 as binder 2.7 parts in terms of solid content, and 0.7 parts of carboxymethyl cellulose aqueous solution having a degree of etherification of 0.8 as a thickener are added in solid content, and an appropriate amount of ion-exchanged water is added to add planetary. A composite particle slurry for negative electrode having a solid content concentration of 20% was prepared by mixing and dispersing with a mixer.

Production of composite particles for negative electrode The composite particle slurry for negative electrode obtained above was sprayed using a spray drier (Okawara Chemical Co., Ltd.) and a rotating disk type atomizer (diameter 65 mm), rotating at 25,000 rpm. Then, spray drying granulation was performed under conditions of a hot air temperature of 150 ° C. and a particle recovery outlet temperature of 90 ° C. to obtain composite particles for a positive electrode. The average volume particle diameter of the obtained composite particles was 40 μm.

Production of Negative Electrode The negative electrode composite particles obtained above were placed on a roll (rolling rough surface heat roll, manufactured by Hirano Giken Kogyo Co., Ltd.) in a roll (roll temperature 100 ° C., press linear pressure 4.0 kN / cm). The negative electrode which supplied with the copper foil as an electrical power collector, shape | molded on the copper foil as an electrical power collector with the shaping | molding speed | rate of 20 m / min, and has a negative electrode active material layer with a thickness of 80 micrometers was obtained.

Production of Lithium Ion Secondary Battery The positive electrode obtained above was cut into a disk shape with a diameter of 13 mm, and the negative electrode obtained above was cut into a disk shape with a diameter of 14 mm. Then, on a 13 mm disk-shaped positive electrode, a separator composed of a disk-shaped polypropylene porous film having a diameter of 18 mm and a thickness of 25 μm, and a 14 mm disk-shaped negative electrode are laminated in this order, and this is a stainless steel in which a polypropylene packing is installed. It was stored in a steel coin-type outer container (diameter 20 mm, height 1.8 mm, stainless steel thickness 0.25 mm). Next, an electrolytic solution (solvent: ethylene carbonate / diethyl carbonate = 1/2 (volume ratio at 20 ° C.), electrolyte: 1M LiPF ₆ ) is poured into this container so that no air remains, and a polypropylene packing is prepared. A 0.2 mm thick stainless steel cap is placed on the outer container and fixed, the battery can is sealed, and a coin-type lithium ion secondary battery (coin cell CR2032) having a diameter of 20 mm and a thickness of about 2 mm is attached. Manufactured.

  The peel strength and moldability were evaluated using the positive electrode obtained above, and the internal resistance and high temperature cycle characteristics were evaluated using a lithium ion secondary battery. The results are shown in Table 1.

(Examples 2 to 8)
Instead of the aqueous dispersion of the particulate saturated nitrile polymer (A1) obtained in Production Example 1, as a binder used when producing composite particles for positive electrode and composite particles for negative electrode, in Production Examples 2 to 8, respectively. A positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1 except that the aqueous dispersions of the obtained particulate saturated nitrile polymers (A2) to (A8) were used. Evaluation was performed in the same manner. The results are shown in Table 1.

(Comparative Examples 1-5)
Instead of the aqueous dispersion of the particulate saturated nitrile polymer (A1) obtained in Production Example 1, as a binder used when producing composite particles for positive electrode and composite particles for negative electrode, each of Production Examples 9 to 13 was used. A positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1 except that the aqueous dispersions of the obtained particulate saturated nitrile polymers (A9) to (A13) were used, respectively. Evaluation was performed in the same manner. The results are shown in Table 2.

(Comparative Example 6)
As a binder used when producing composite particles for positive electrode and composite particles for negative electrode, instead of the aqueous dispersion of particulate saturated nitrile polymer (A1) obtained in Production Example 1, it was obtained in Production Example 14 respectively. A positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1 except that an N-methylpyrrolidone solution of the saturated nitrile polymer (A14) was used, and evaluation was performed in the same manner. In addition, the compounding quantity of the N-methylpyrrolidone solution of a saturated nitrile polymer (A14) was 1 part in conversion of solid content. The results are shown in Table 2.

(Comparative Example 7)
A composite particle slurry for positive electrode was prepared in the same manner as in Example 1, and the obtained composite particle slurry for positive electrode was applied on an aluminum foil as a current collector with a comma coater and heat-treated at 150 ° C. for 2 hours. An electrode stock was obtained. And the positive electrode whose thickness of a positive electrode active material layer is 80 micrometers was produced by rolling this electrode raw material with a roll press.

  Separately from the above, a negative electrode composite particle slurry was prepared in the same manner as in Example 1, and the obtained negative electrode composite particle slurry was applied onto a copper foil as a current collector with a comma coater, and 150 ° C. The electrode raw material was obtained by heat treatment for 2 hours. And the negative electrode whose thickness of a negative electrode active material layer is 80 micrometers was produced by rolling an electrode raw material with a roll press.

  And the lithium ion secondary battery was manufactured similarly to Example 1 except having used the positive electrode and negative electrode which were obtained above, and it evaluated similarly. The results are shown in Table 2.

(Comparative Example 8)
Particulate saturation is achieved by adding 320 parts of N-methylpyrrolidone to 100 parts of the aqueous dispersion of the particulate saturated nitrile polymer (A1) obtained in Production Example 1 and then evaporating water under reduced pressure. An N-methylpyrrolidone solution of the nitrile polymer (A1) was obtained. The particulate saturated nitrile polymer (A1) did not have a particle shape in the N-methylpyrrolidone solution.

  And instead of the N-methylpyrrolidone solution of the saturated nitrile polymer (A14) obtained in Production Example 14, the N-methylpyrrolidone solution of the particulate saturated nitrile polymer (A1) obtained above. A composite particle slurry for a positive electrode and a composite particle slurry for a negative electrode were obtained in the same manner as in Comparative Example 7 except that was used.

  Then, using the composite particle slurry for positive electrode and the composite particle slurry for negative electrode obtained above, in the same manner as in Comparative Example 7, a positive electrode and a negative electrode were prepared. A secondary battery was manufactured and evaluated in the same manner. The results are shown in Table 2.

  As shown in Table 1, when the predetermined particulate binder of the present invention is used, the obtained electrode is excellent in peel strength and moldability, has low internal resistance when used as a battery, and is excellent in high temperature cycle characteristics. (Examples 1-8).

On the other hand, when using too many acrylonitrile units as the particulate binder, the moldability decreased when used as an electrode, resulting in decreased internal resistance and high-temperature cycle characteristics when used as a battery ( Comparative Example 1).
In addition, when using a binder having too few acrylonitrile units as a particulate binder, or using a binder having an iodine value that is too low, the peel strength and moldability are reduced when used as an electrode. As a result, the internal resistance and the high-temperature cycle characteristics were also reduced (Comparative Examples 2 and 4).
Furthermore, when a particulate binder having an iodine value that is too high was used, the internal resistance and high-temperature cycle characteristics of the battery were reduced (Comparative Example 3).

Alternatively, when a particulate binder that does not contain a monomer unit having an acidic functional group is used, the peel strength decreases when an electrode is used, and the internal resistance and high temperature cycle when a battery is used The characteristic was also deteriorated (Comparative Example 5).
Furthermore, since the hydrogenation reaction in producing the binder was performed in acetone, when using a binder that does not have a particle shape, or when an electrode is formed by coating, peel strength and molding when the electrode is used As a result, the internal resistance and high-temperature cycle characteristics of the battery were also reduced (Comparative Examples 6 and 7).
In addition, as a result of dissolving the particulate binder in N-methylpyrrolidone, it becomes a state having no particle shape, and when the binder is used in a state not having the particle shape, the internal resistance and the high temperature cycle when used as a battery are obtained. The characteristic was also deteriorated (Comparative Example 8).
Of the above comparative examples, in Comparative Example 7, corrosion of the aluminum foil was caused by directly applying an aqueous dispersion slurry containing LiNiO ₂ as the positive electrode active material to the aluminum foil as the current collector. It became. Moreover, in Comparative Examples 7 and 8, since the positive electrode and the negative electrode were formed by coating, there was also a problem that the binder was unevenly distributed on the surface of the electrode active material layer.

Claims (8)

Comprising an electrode active material and a particulate binder;
The binder contains a nitrile group-containing monomer unit, a monomer unit having an acidic functional group, and a linear alkylene structure-containing monomer unit having 4 or more carbon atoms, and the nitrile group-containing monomer unit A composite particle for an electrochemical element electrode, which is a copolymer having a content ratio of 10 to 50% by weight and an iodine value of 3 to 40 mg / 100 mg.   2. The composite particle for an electrochemical element electrode according to claim 1, wherein the acidic functional group is at least one selected from a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group.   An electrochemical element electrode material comprising the composite particle for an electrochemical element electrode according to claim 1.   An electrochemical element electrode, comprising an active material layer formed of the electrochemical element electrode material according to claim 3 and laminated on a current collector.   The electrochemical element electrode according to claim 4, wherein the active material layer is laminated on the current collector by pressure molding.   6. The electrochemical element electrode according to claim 5, wherein the active material layer is laminated on the current collector by roll pressing.   An electrochemical device comprising the electrochemical device electrode according to claim 4. A method for producing the composite particle for an electrochemical element electrode according to claim 1 or 2,
The manufacturing method of the composite particle for electrochemical element electrodes which has the process of dispersing the said electrode active material and the said binder in water, and obtaining the slurry, and spray-drying the said slurry and granulating.