JPWO2015141464A1 - Composite particles for electrochemical device electrodes - Google Patents

Abstract

A composite particle for an electrochemical element electrode comprising a positive electrode active material (A), a conductive agent (B), a particulate binder resin (C), a water-soluble polymer (D) and a water-insoluble polysaccharide polymer fiber (E) Then, the water-soluble polymer (D) and the water-insoluble polysaccharide polymer fiber (E) are included in a weight ratio of (D) / (E) = 0.25 to 7.0.

Description

  The present invention relates to composite particles for electrochemical element electrodes.

  The demand for electrochemical devices such as lithium-ion secondary batteries, electric double-layer capacitors, and lithium-ion capacitors is rapidly expanding by taking advantage of the small size, light weight, high energy density, and the ability to repeatedly charge and discharge. doing. Lithium ion secondary batteries have a relatively high energy density and are used in mobile fields such as mobile phones and notebook personal computers. On the other hand, since the electric double layer capacitor can be rapidly charged and discharged, the electric double layer capacitor is expected to be used as an auxiliary power source for an electric vehicle or the like in addition to being used as a memory backup small power source for a personal computer or the like. Furthermore, the lithium ion capacitor that takes advantage of the lithium ion secondary battery and the electric double layer capacitor has higher energy density and output density than the electric double layer capacitor. Application to applications that could not meet the specifications for capacitor performance is being considered. Among these, in particular, lithium ion secondary batteries have been studied for application not only to in-vehicle applications such as hybrid electric vehicles and electric vehicles, but also to power storage applications.

  While expectations for these electrochemical devices have increased, these electrochemical devices have further improvements such as lower resistance, higher capacity, and improved mechanical properties and productivity as applications expand and develop. It has been demanded. Under such circumstances, there is 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 an electrochemical element electrode material suitable for the manufacturing method. Has been done.

  An electrode for an electrochemical element is usually formed by laminating an electrode active material layer formed by binding an electrode active material and a conductive agent used as necessary with a binder resin on a current collector. Is. Electrodes for electrochemical devices include coated electrodes manufactured by a method in which a slurry for coated electrodes containing an electrode active material, a binder resin, a conductive agent, etc. is coated on a current collector and the solvent is removed by heat or the like. However, it has been difficult to produce a uniform electrochemical device due to migration of a binder resin or the like. In addition, this method has a high cost and a poor working environment, and the manufacturing apparatus tends to be large.

  On the other hand, it has been proposed to obtain an electrochemical element having a uniform electrode active material layer by obtaining composite particles and powder molding. As a method of forming such an electrode active material layer, for example, Patent Document 1 discloses composite particles obtained by spraying and drying a slurry for composite particles containing an electrode active material, a binder resin, and a dispersion medium. A method of forming an electrode active material layer using composite particles is disclosed. Since such composite particles may be destroyed during transfer such as pneumatic transportation, improvement in strength is required.

  Here, when the electrode active material layer is formed using the broken composite particles, the uniformity of the particle size of the composite particles is lost, so that the fluidity of the powder is deteriorated and a uniform electrode active material layer is formed. Can not be. In addition, the adhesion between the composite particles and the adhesion between the electrode active material layer and the current collector were weakened, and the cycle characteristics of the resulting electrochemical device were not sufficient. Moreover, the electrode which has the electrode active material layer formed using the broken composite particle is inferior in a softness | flexibility, and when the electrode was wound, the electrode might crack.

  Further, in Patent Document 1, externally added particles obtained by coating the surface of the composite particles with a fibrous conductive assistant are obtained, but since the fibrous conductive assistant is not present inside the composite particles, the composite particles It was not possible to improve the strength.

  Patent Document 2 describes that carbon fiber is contained in a slurry for a coating electrode for coating an electrode to form an electrode layer in order to improve adhesion in the coating electrode. However, since it relates to a method for producing the coated electrode, which is different from powder molding using composite particles, it has not been described to improve the strength of the composite particles.

  Patent Document 3 describes that finely divided cellulose fibers are contained in a slurry for a coating electrode that is applied to an electrode to form an electrode layer in order to improve adhesion in the coating electrode. However, since it relates to a method for producing the coated electrode, which is different from powder molding using composite particles, it has not been described to improve the strength of the composite particles.

International Publication No. 2009/44856 JP 2009-295666 A International Publication No. 2013/42720

  An object of the present invention is an electrochemical device having sufficient strength, excellent uniformity, sufficient adhesion when forming an electrode, and an electrode having excellent flexibility. It is to provide composite particles for electrodes.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above object can be achieved by obtaining composite particles by using a water-soluble polymer and a water-insoluble polysaccharide polymer fiber in combination at a predetermined ratio. The present invention has been completed.

That is, according to the present invention,
(1) For an electrochemical device electrode including a positive electrode active material (A), a conductive agent (B), a particulate binder resin (C), a water-soluble polymer (D), and a water-insoluble polysaccharide polymer fiber (E) A composite particle, wherein the water-soluble polymer (D) and the water-insoluble polysaccharide polymer fiber (E) are in a ratio of (D) / (E) = 0.25 to 7.0 by weight ratio. Composite particles for electrochemical element electrodes, characterized in that
(2) The composite particle for an electrochemical element electrode according to (1), wherein the water-insoluble polysaccharide polymer fiber (E) has an average degree of polymerization of 50 to 1000,
(3) The particulate binder resin (C) is an acrylate polymer, wherein the composite particles for electrochemical element electrodes according to (1) or (2),
(4) The amount of the water-soluble polymer (D) is 0.1 to 10 parts by weight in terms of solid content with respect to 100 parts by weight of the positive electrode active material (A), and the water-insoluble polysaccharide polymer fiber The electricity according to any one of (1) to (3), wherein the blending amount of (E) is 0.1 to 2 parts by weight in terms of solid content with respect to 100 parts by weight of the composite particles obtained. Composite particles for chemical element electrodes are provided.

  ADVANTAGE OF THE INVENTION According to this invention, it is the electrochemical element which has sufficient intensity | strength, is excellent in the uniformity, can acquire sufficient adhesiveness when forming an electrode, and can obtain the electrode which is further excellent in a softness | flexibility. Electrode composite particles can be provided.

  Hereinafter, the composite particle for an electrochemical element electrode according to an embodiment of the present invention will be described. The composite particle for an electrochemical element electrode of the present invention (hereinafter sometimes referred to as “composite particle”) includes a positive electrode active material (A), a conductive agent (B), a particulate binder resin (C), An electrochemical device electrode composite particle comprising a molecule (D) and a water-insoluble polysaccharide polymer fiber (E), wherein the water-soluble polymer (D) and the water-insoluble polysaccharide polymer fiber (E) The ratio is (D) / (E) = 0.25 to 7.0.

  In the following, “positive electrode active material” means an electrode active material for positive electrode, and “negative electrode active material” means an electrode active material for negative electrode. The “positive electrode active material layer” means an electrode active material layer provided on the positive electrode, and the “negative electrode active material layer” means an electrode active material layer provided on the negative electrode.

(Positive electrode active material (A))
As the positive electrode active material (A) when the electrochemical element is a lithium ion secondary battery, an active material capable of doping and dedoping lithium ions is used, and the positive electrode active material (A) is composed of an inorganic compound and an organic compound. Broadly divided.

  Examples of the positive electrode active material (A) made of an inorganic compound include transition metal oxides, transition metal sulfides, lithium-containing composite metal oxides of lithium and transition metals, and the like. Examples of the transition metal include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Mo.

Transition metal oxides include MnO, MnO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , Cu ₂ V ₂ O ₃ , amorphous V ₂ O—P ₂ O ₅ , MoO ₃ , V ₂ O. ₅ , V ₆ O _{13 and the} like. Among them, MnO, V ₂ O ₅ , V ₆ O ₁₃ and TiO ₂ are preferable from the viewpoint of cycle stability and capacity. The transition metal sulfide, TiS _2, TiS _3, amorphous MoS _2, FeS, and the like. Examples of the lithium-containing composite metal oxide include a lithium-containing composite metal oxide having a layered structure, a lithium-containing composite metal oxide having a spinel structure, and a lithium-containing composite metal oxide having an olivine structure.

Examples of the lithium-containing composite metal oxide having a layered structure include lithium-containing cobalt oxide (LiCoO ₂ ) (hereinafter sometimes referred to as “LCO”), lithium-containing nickel oxide (LiNiO ₂ ), and Co—Ni—Mn. Examples thereof include a lithium composite oxide, a lithium composite oxide of Ni—Mn—Al, and a lithium composite oxide of Ni—Co—Al. Examples of the lithium-containing composite metal oxide having a spinel structure include lithium manganate (LiMn ₂ O ₄ ) and Li [Mn _3/2 M _1/2 ] O _{4 in} which a part of Mn is substituted with another transition metal (here, M may be Cr, Fe, Co, Ni, Cu or the like. Li _x MPO ₄ (wherein, M is Mn, Fe, Co, Ni, Cu, Mg, Zn, V, Ca, Sr, Ba, Ti, Al, and the like) is a lithium-containing composite metal oxide having an olivine structure. An olivine type lithium phosphate compound represented by at least one selected from Si, B, and Mo, 0 ≦ X ≦ 2) may be mentioned.

  As the organic compound, for example, a conductive polymer such as polyacetylene or poly-p-phenylene can be used. An iron-based oxide having poor electrical conductivity may be used as a positive electrode active material covered with a carbon material by allowing a carbon source material to be present during reduction firing. These compounds may be partially element-substituted. The positive electrode active material may be a mixture of the above inorganic compound and organic compound.

  In the case where the electrochemical element is a lithium ion capacitor, the positive electrode active material may be any material that can reversibly carry lithium ions and anions such as tetrafluoroborate. Specifically, carbon allotropes can be preferably used, and electrode active materials used in electric double layer capacitors can be widely used. Specific examples of the allotrope of carbon include activated carbon, polyacene (PAS), carbon whisker, carbon nanotube, and graphite.

  The volume average particle diameter of the positive electrode active material (A) is appropriately selected in consideration of other components of the electrode for an electrochemical element, but from the viewpoint of improving the characteristics of the electrochemical element such as load characteristics and cycle characteristics, Preferably it is 1-50 micrometers, More preferably, it is 2-30 micrometers.

(Conducting agent (B))
The conductive agent (B) used in the present invention is not particularly limited as long as it is a conductive material, but is preferably a particulate material having conductivity, such as furnace black, acetylene black, and ketjen black. Examples thereof include conductive carbon black; graphite such as natural graphite and artificial graphite; and carbon fibers such as polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, and vapor grown carbon fiber. The average particle diameter when the conductive agent (B) is a particulate material is not particularly limited, but is preferably smaller than the average particle diameter of the positive electrode active material, and sufficient conductivity can be expressed with a smaller amount of use. From the viewpoint, it is preferably 0.001 to 10 μm, more preferably 0.05 to 5 μm, and still more preferably 0.1 to 1 μm.

  The compounding amount of the conductive agent (B) in the composite particle for an electrochemical element electrode of the present invention is 100% by weight of the positive electrode active material from the viewpoint of sufficiently reducing the internal resistance while keeping the capacity of the obtained electrochemical element high. The amount is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 15 parts by weight, and still more preferably 1 to 10 parts by weight with respect to parts.

(Particulate binder resin (C))
The particulate binder resin (C) used in the present invention is not particularly limited as long as it is a substance capable of binding the above-described positive electrode active materials to each other. As the particulate binder resin (C), a dispersion type particulate binder resin having a property of being dispersed in a solvent is preferable. Examples of the dispersion-type particulate binder resin include high molecular compounds such as silicon polymers, fluorine-containing polymers, conjugated diene polymers, acrylate polymers, polyimides, polyamides, and polyurethanes. From the viewpoint of good adhesion between the molecule (D) and the water-insoluble polysaccharide polymer fiber (E), a fluorine-containing polymer, a conjugated diene polymer, and an acrylate polymer are preferable, and a conjugated diene polymer and An acrylate polymer is more preferable. These polymers can be used alone or in combination as a dispersion type particulate binder resin.

  The fluorine-containing polymer is a polymer containing a monomer unit containing a fluorine atom. Specific examples of the fluorine-containing polymer include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, ethylene / tetrafluoroethylene copolymer, ethylene / chlorotrifluoroethylene copolymer, A perfluoroethylene propene copolymer may be mentioned.

  The conjugated diene polymer is a homopolymer of a conjugated diene monomer or a copolymer obtained by polymerizing a monomer mixture containing a conjugated diene monomer, or a hydrogenated product thereof. As conjugated diene monomers, 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, substituted linear conjugated pentadiene It is preferable to use alkenyl, substituted and side chain conjugated hexadienes, etc., and 1,3-butadiene is used in that it can improve flexibility when used as an electrode and can have high resistance to cracking. It is more preferable. Further, the monomer mixture may contain two or more of these conjugated diene monomers.

  When the conjugated diene polymer is a copolymer of the above conjugated diene monomer and a monomer copolymerizable therewith, examples of the copolymerizable monomer include α, Examples thereof include β-unsaturated nitrile compounds and vinyl compounds having an acid component.

  Specific examples of conjugated diene polymers include conjugated diene monomer homopolymers such as polybutadiene and polyisoprene; aromatic vinyl monomers such as carboxy-modified styrene-butadiene copolymer (SBR). Monomer / conjugated diene monomer copolymer; vinyl cyanide monomer / conjugated diene monomer copolymer such as acrylonitrile / butadiene copolymer (NBR); hydrogenated SBR, hydrogenated NBR, etc. Is mentioned.

  The blending amount of the conjugated diene monomer unit in the conjugated diene polymer is preferably 20 to 60% by weight, more preferably 30 to 55% by weight. When the compounding amount of the conjugated diene monomer unit is too large, when the positive electrode is produced using composite particles containing the particulate binder resin (C), the electrolytic solution resistance tends to decrease. If the blending amount of the conjugated diene monomer unit is too small, sufficient adhesion between the composite particles and the current collector tends not to be obtained.

The acrylate polymer has the general formula (1): CH ₂ ═CR ¹ —COOR ² (wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group or a cycloalkyl group. R ² further represents A monomer unit derived from a compound represented by an ether group, a hydroxyl group, a phosphate group, an amino group, a carboxyl group, a fluorine atom, or an epoxy group. Copolymer obtained by polymerizing a polymer containing, specifically, a homopolymer of a compound represented by the general formula (1) or a monomer mixture containing the compound represented by the general formula (1) It is a coalescence. Specific examples of the compound represented by the general formula (1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylate n. -Butyl, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isopentyl (meth) acrylate, isooctyl (meth) acrylate, isobornyl (meth) acrylate, (meth) (Meth) acrylic acid alkyl esters such as isodecyl acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and tridecyl (meth) acrylate; butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate , (Meth) acrylic acid methoxydipropylene Recall, (meth) acrylic acid methoxypolyethylene glycol, (meth) acrylic acid phenoxyethyl, (meth) acrylic acid tetrahydrofurfuryl ether group-containing (meth) acrylic acid ester; (meth) acrylic acid-2-hydroxyethyl, Hydroxyl-containing (meth) acrylic such as (meth) acrylic acid-2-hydroxypropyl, (meth) acrylic acid-2-hydroxy-3-phenoxypropyl, 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid Acid esters; 2- (meth) acryloyloxyethylphthalic acid-containing (meth) acrylic acid esters; (meth) acrylic acid perfluorooctylethyl fluorine-containing (meth) acrylic acid esters; (meth) Phosphoric acid group-containing (meth) acrylates such as ethyl acrylate Acrylic acid esters; (meth) epoxy group-containing (meth) acrylic acid esters of glycidyl acrylate; (meth) containing amino group such as dimethylaminoethyl acrylate (meth) acrylic acid ester; and the like.

  In the present specification, “(meth) acryl” means “acryl” and “methacryl”. “(Meth) acryloyl” means “acryloyl” and “methacryloyl”.

  These (meth) acrylic acid esters can be used alone or in combination of two or more. Among these, (meth) acrylic acid alkyl ester is preferable, and (meth) acrylic acid methyl, (meth) acrylic acid ethyl, and (meth) acrylic acid n-butyl and the alkyl group have 6 to 12 carbon atoms. (Meth) acrylic acid alkyl ester is more preferred. By selecting these, it becomes possible to reduce the swellability with respect to the electrolytic solution, and to improve the cycle characteristics.

  In addition, when the acrylate polymer is a copolymer of the compound represented by the general formula (1) and a monomer copolymerizable therewith, as the copolymerizable monomer, For example, carboxylic acid esters having two or more carbon-carbon double bonds, aromatic vinyl monomers, amide monomers, olefins, diene monomers, vinyl ketones, and heterocyclic rings In addition to vinyl compounds, α, β-unsaturated nitrile compounds and vinyl compounds having an acid component are mentioned.

  Among the above copolymerizable monomers, the electrode (positive electrode) can be made difficult to be deformed and strong, and sufficient adhesion between the positive electrode active material layer and the current collector can be obtained. In view of the obtained point, it is preferable to use an aromatic vinyl monomer. Examples of the aromatic vinyl monomer include styrene.

  In addition, when there is too much compounding quantity of an aromatic vinyl-type monomer, there exists a tendency for sufficient adhesiveness of a positive electrode active material layer and a collector to be not acquired. Moreover, when there are too few compounding quantities of an aromatic vinyl-type monomer, there exists a tendency for electrolyte solution resistance to fall, when manufacturing a positive electrode.

  The blending amount of the (meth) acrylic acid ester unit in the acrylate polymer can improve flexibility when the electrode (positive electrode) is used, and is preferably 50 to 50% from the viewpoint of increasing resistance to cracking. It is 95 weight%, More preferably, it is 60 to 90 weight%.

  Examples of the α, β-unsaturated nitrile compound used in the polymer constituting the particulate binder resin (C) include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and α-bromoacrylonitrile. These may be used alone or in combination of two or more. Among these, acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is more preferable.

  The blending amount of the α, β-unsaturated nitrile compound unit in the particulate binder resin (C) is preferably 0.1 to 40% by weight, more preferably 0.5 to 30% by weight, and still more preferably 1 to 20% by weight. When the α, β-unsaturated nitrile compound unit is contained in the particulate binder resin (C), it is difficult to be deformed when the electrode (positive electrode) is produced, and the strength can be increased. Further, when the α, β-unsaturated nitrile compound unit is contained in the particulate binder resin (C), the adhesion between the positive electrode active material layer containing the composite particles and the current collector may be sufficient. it can.

  In addition, when there are too many compounding quantities of an (alpha), (beta)-unsaturated nitrile compound unit, there exists a tendency for sufficient adhesiveness of a positive electrode active material layer and a collector to be not acquired. Moreover, when there are too few compounding quantities of an (alpha), (beta)-unsaturated nitrile compound unit, when manufacturing a positive electrode, there exists a tendency for electrolyte solution resistance to fall.

  Examples of the vinyl compound having an acid component include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid. These may be used alone or in combination of two or more. Among these, acrylic acid, methacrylic acid, and itaconic acid are preferable, methacrylic acid and itaconic acid are more preferable, and itaconic acid is particularly preferable in terms of improving adhesive strength.

  The compounding amount of the vinyl compound unit having an acid component in the dispersion type particulate binder resin is preferably 0.5 to 10% by weight, more preferably from the viewpoint of improving the stability when the slurry for composite particles is used. Is 1-8 wt%, more preferably 2-7 wt%.

  In addition, when there are too many compounding quantities of the vinyl compound unit which has an acid component, there exists a tendency for the viscosity of the slurry for composite particles to become high, and for handling to become difficult. Moreover, when there are too few compounding quantities of the vinyl compound unit which has an acid component, there exists a tendency for stability of the slurry for composite particles to fall.

  Since the particulate binder resin (C) used in the present invention is particulate, it has good binding properties and can suppress deterioration of the capacity of the produced electrode and repeated charge / discharge. Examples of the particulate binder resin (C) include those in which binder resin particles such as latex are dispersed in water, and powders obtained by drying such a dispersion.

  The average particle diameter of the particulate binder resin (C) is preferably from the viewpoint that the strength and flexibility of the positive electrode to be obtained are good while the stability when the composite particle slurry is obtained is good. It is 001-100 micrometers, More preferably, it is 10-1000 nm, More preferably, it is 50-500 nm.

  The method for producing the particulate binder resin (C) used in the present invention is not particularly limited, and a known polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, or a solution polymerization method may be employed. it can. Among these, it is preferable to produce by an emulsion polymerization method because the particle diameter of the particulate binder resin (C) can be easily controlled. The particulate binder resin (C) used in the present invention may be a particle having a core-shell structure obtained by stepwise polymerization of a mixture of two or more monomers.

  The compounding amount of the particulate binder resin (C) in the composite particle for an electrochemical element electrode of the present invention can ensure sufficient adhesion between the obtained positive electrode active material layer and the current collector, and the electrochemical element From the viewpoint of reducing the internal resistance of the positive electrode active material (A), it is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the positive electrode active material (A). More preferably, it is 1 to 15 parts by weight.

(Water-soluble polymer (D))
The water-soluble polymer (D) used in the present invention refers to a polymer having an undissolved content of less than 10.0% by weight when 0.5 g of the polymer is dissolved in 100 g of pure water at 25 ° C.

  Specific examples of the water-soluble polymer (D) include cellulosic polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose and hydroxypropylcellulose, and ammonium salts or alkali metal salts thereof, alginates such as propylene glycol alginate, and alginic acid. Alginates such as sodium, polyacrylic acid, and polyacrylic acid (or methacrylic acid) salts such as sodium polyacrylic acid (or methacrylic acid), polyvinyl alcohol, modified polyvinyl alcohol, poly-N-vinylacetamide, polyethylene oxide, polyvinyl Examples include pyrrolidone, polycarboxylic acid, oxidized starch, phosphate starch, casein, various modified starches, chitin, chitosan derivatives, etc. It is. In the present invention, “(modified) poly” means “unmodified poly” or “modified poly”.

  These water-soluble polymers (D) can be used alone or in combination of two or more. Among these, from the viewpoint of improving the dispersibility of the water-insoluble polysaccharide polymer fiber (E) and having high adhesiveness, a cellulose-based polymer is preferable, and carboxymethyl cellulose or its ammonium salt or alkali metal salt is particularly preferable. The blending amount of these water-soluble polymers (D) is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 0 with respect to 100 parts by weight of the positive electrode active material in terms of solid part. 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, and still more preferably 0.25 to 2 parts by weight.

(Water-insoluble polysaccharide polymer fiber (E))
The water-insoluble polysaccharide polymer fiber (E) used in the present invention belongs to a so-called polymer compound among polysaccharides, and there is no other limitation as long as it is a water-insoluble fiber. Usually, it is a fiber (short fiber) fibrillated by a mechanical shearing force. In addition, the water-insoluble polysaccharide polymer fiber used in the present invention is a high-polysaccharide fiber having an undissolved content of 90% by weight or more when 0.5 g of polysaccharide polymer fiber is dissolved in 100 g of pure water at 25 ° C. Refers to molecular fiber.

  As the water-insoluble polysaccharide polymer fiber (E), it is preferable to use polysaccharide polymer nanofibers. Among the polysaccharide polymer nanofibers, they are flexible and have a high tensile strength. From the viewpoint that the particle reinforcing effect is high, the particle strength can be improved, and the dispersibility of the conductive agent (B) is improved, it is derived from organisms such as cellulose nanofibers, chitin nanofibers, chitosan nanofibers, etc. It is more preferable to use single or any mixture selected from bionanofiber. Among these, it is more preferable to use cellulose nanofibers, and it is particularly preferable to use cellulose nanofibers made from bamboo, conifers, hardwoods, and cotton.

  As a method of fibrillating (shortening fiber) by applying mechanical shearing force to these water-insoluble polysaccharide polymer fibers (E), a method in which water-insoluble polysaccharide polymer fibers are dispersed in water and then beaten. And a method of passing through an orifice. As the water-insoluble polysaccharide polymer fiber, short fibers having various fiber diameters are commercially available, and these may be used by dispersing in water.

  The average fiber diameter of the water-insoluble polysaccharide polymer fiber (E) used in the present invention is such that more water-insoluble polysaccharide polymer fiber (E) is present in the composite particles and the adhesion between the positive electrode active materials is strengthened. From the viewpoint of ensuring sufficient strength of the composite particles and the electrode (positive electrode), and from the viewpoint of excellent electrochemical characteristics of the obtained electrochemical device, preferably 5 to 3000 nm, more preferably 5 to 2000 nm, and still more preferably. The thickness is 5 to 1000 nm, particularly preferably 5 to 100 nm. When the average fiber diameter of the water-insoluble polysaccharide polymer fiber (E) is too large, the water-insoluble polysaccharide polymer fiber cannot sufficiently exist in the composite particle, so that the strength of the composite particle is sufficient. I can't. Further, the fluidity of the composite particles is deteriorated, and it is difficult to form a uniform positive electrode active material layer.

  In addition, the water-insoluble polysaccharide polymer fiber (E) may be composed of a single fiber that is sufficiently separated without being aligned. In this case, the average fiber diameter is the average diameter of single fibers. Further, the water-insoluble polysaccharide polymer fiber (E) may be one in which a plurality of single fibers are gathered in a bundle to form one yarn. In this case, the average fiber diameter is defined as the average value of the diameters of one yarn.

  In addition, the average degree of polymerization of the water-insoluble polysaccharide polymer fiber (E) is obtained from the viewpoint of sufficient strength of the composite particles and the electrode (positive electrode), and the formation of a uniform positive electrode active material layer. From a viewpoint which is excellent in the electrochemical characteristic of a chemical element, Preferably it is 50-1000, More preferably, it is 100-900, More preferably, it is 150-800. If the average degree of polymerization of the water-insoluble polysaccharide polymer fiber is too large, the internal resistance of the resulting electrochemical device increases. In addition, it becomes difficult to form a uniform positive electrode active material layer. Moreover, when the average degree of polymerization of the water-insoluble polysaccharide polymer fiber is too small, the strength of the composite particles becomes insufficient.

In the present invention, the average degree of polymerization is determined by a viscosity method using the following copper ethylenediamine solution.
A freeze-dried water-insoluble polysaccharide polymer fiber is dissolved in a copper ethylenediamine solution 1 to prepare a solution 2, and the viscosity is measured using a viscometer. The intrinsic viscosity [η] of the water-insoluble polysaccharide polymer fiber solution is obtained by the following calculation formula where the viscosity of the solution 2 is η and the viscosity of the solution 1 is η0.

Intrinsic viscosity [η] = (η / η0) / {c (1 + A × η / η0)}
Here, c is the water-insoluble polysaccharide polymer fiber concentration (g / dL), and A is a value determined by the type of the solution 1. When 0.5 M copper ethylenediamine solution is used as solution 1, A is 0.28.

And average polymerization degree DP is calculated | required from the following formula | equation.
Intrinsic viscosity [η] = K × DP ^a
Here, K and a are values determined by the type of polymer. For example, in the case of cellulose, K is 5.7 × 10 ⁻³ and a is 1.

  The viscometer is preferably a capillary viscometer, examples of which include a Canon-Fenske viscometer.

  The blending amount of the water-insoluble polysaccharide polymer fiber (E) is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1. 5 parts by weight, more preferably 0.3 to 1 part by weight. When the blending amount of the water-insoluble polysaccharide polymer fiber is too large, the internal resistance of the obtained electrochemical element increases. In addition, it becomes difficult to form a uniform electrode layer (positive electrode active material layer). Moreover, when there are too few compounding quantities of water-insoluble polysaccharide polymer fiber (E), the reinforcement effect by water-insoluble polysaccharide polymer fiber will be small, and the intensity | strength of composite particle will become inadequate. Moreover, when there are too few compounding quantities of a water-insoluble polysaccharide polymer fiber (E), the softness | flexibility of an electrode will worsen. Moreover, when there are too many compounding quantities of water-insoluble polysaccharide polymer fiber (E), granulation of a composite particle cannot be performed.

  In addition, when the viscosity of the slurry for composite particles increases by increasing the blending amount of the water-insoluble polysaccharide polymer fiber (E), the viscosity is appropriately adjusted by reducing the blending amount of the water-soluble polymer. Can do.

  The ratio between the water-soluble polymer (D) and the water-insoluble polysaccharide polymer fiber (E) used in the present invention is determined from the viewpoint of improving the dispersibility of the water-insoluble polysaccharide polymer fiber (E). In terms of weight ratio in terms of conversion, water-soluble polymer (D) / water-insoluble polysaccharide polymer fiber (E) = 0.25 to 7.0, preferably 0.3 to 6.0, more preferably 0.4. -5.0. If the value of the water-soluble polymer (D) / water-insoluble polysaccharide polymer fiber (E) is too large, the storage stability of the composite particle slurry will deteriorate. Moreover, when the value of water-soluble polymer (D) / water-insoluble polysaccharide polymer fiber (E) is too small, the strength of the composite particles becomes insufficient.

(Manufacture of composite particles)
The composite particles are added to the positive electrode active material (A), the conductive agent (B), the particulate binder resin (C), the water-soluble polymer (D), the water-insoluble polysaccharide polymer fiber (E), and if necessary. It is obtained by granulating using other components. The composite particle includes the positive electrode active material (A) and the particulate binder resin (C), and each of the positive electrode active material (A) and the particulate binder resin (C) exists as independent particles. Instead, one particle is formed by two or more components including the positive electrode active material (A) and the particulate binder resin (C), which are constituent components. Specifically, a plurality of (preferably several to several tens) secondary particles are formed by combining a plurality of individual particles of the two or more components in a state where the shape is substantially maintained. The positive electrode active material (A) is preferably bound with the particulate binder resin (C) to form particles.

The shape of the composite particles is preferably substantially spherical from the viewpoint of fluidity. That is, the short axis diameter of the composite particles is L _s , the long axis diameter is L _l , L _a = (L _s + L _l ) / 2, and a value of (1− (L _l −L _s ) / L _a ) × 100 Is a sphericity (%), the sphericity is preferably 80% or more, more preferably 90% or more. Here, the minor axis diameter L _s and the major axis diameter L _l are values measured from a scanning electron micrograph image.

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

  The production method of the composite particles is not particularly limited, but is spray drying granulation method, rolling bed granulation method, compression granulation method, stirring granulation method, extrusion granulation method, crushing granulation method, fluidized bed granulation method. Composite particles can be obtained by production methods such as a granulation method, a fluidized bed multifunctional granulation method, and a melt granulation method.

The production method of the composite particles may be appropriately selected from the viewpoints of ease of particle size control, productivity, ease of control of particle size distribution, etc. according to the components of the composite particles, etc. The spray-drying granulation method described in 1 is preferable because the composite particles can be produced relatively easily.
Hereinafter, the spray drying granulation method will be described.

  First, a slurry for composite particles containing a positive electrode active material (A), a conductive agent (B), a particulate binder resin (C), a water-soluble polymer (D), and a water-insoluble polysaccharide polymer fiber (E) ( Hereinafter, it may be referred to as “slurry”). The composite particle slurry includes a positive electrode active material (A), a conductive agent (B), a particulate binder resin (C), a water-soluble polymer (D), a water-insoluble polysaccharide polymer fiber (E), and as necessary. The other components to be added can be prepared by dispersing or dissolving in a solvent. In this case, when the particulate binder resin (C) is dispersed in water as a solvent, it can be added in a state dispersed in water.

  As the solvent used for obtaining the composite particle slurry, water is preferably used, but a mixed solvent of water and an organic solvent may be used, or only an organic solvent may be used alone or in combination. Examples of the organic solvent that can be used in this case include 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, dimethyl Amides such as acetamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone; and the like. When using an organic solvent, alcohols are preferred. By using water and an organic solvent having a lower boiling point than water, the drying rate can be increased during spray drying. Thereby, the viscosity and fluidity of the slurry for composite particles can be adjusted, and the production efficiency can be improved.

  The viscosity of the composite particle slurry is preferably 10 to 3,000 mPa · s, more preferably 30 to 1,500 mPa · s, and even more preferably at room temperature from the viewpoint of improving the productivity of the spray drying granulation step. Is 50 to 1,000 mPa · s.

  Moreover, in this invention, when preparing the slurry for composite particles, you may add a dispersing agent and surfactant as needed. Examples of the surfactant include amphoteric surfactants such as anionic, cationic, nonionic, and nonionic anions, and anionic or nonionic surfactants 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 positive electrode active material. .

  From the viewpoint of uniformly dispersing the binder resin in the slurry, the amount of the solvent used in preparing the slurry is preferably 1 to 70% by weight, more preferably 5 to 70% by weight, based on the solid content concentration of the slurry. More preferably, the amount is 10 to 65% by weight.

  Positive electrode active material (A), conductive agent (B), particulate binder resin (C), water-soluble polymer (D) and water-insoluble polysaccharide polymer fiber (E), and other added as necessary The method or order of dispersing or dissolving the components in the solvent is not particularly limited. For example, the positive electrode active material (A), the conductive agent (B), the particulate binder resin (C), and the water-soluble polymer (D) are used in the solvent. ) And a water-insoluble polysaccharide polymer fiber (E), and after mixing the water-soluble polymer (D) in a solvent, the positive electrode active material (A), the conductive agent (B) and the water-insoluble polysaccharide Method of adding and mixing the polymer fiber (E) and finally mixing the particulate binder resin (C) (for example, latex) dispersed in the solvent, and the particulate binder dispersed in the solvent The positive electrode active material (A) and the conductive agent (B) are added to the resin (C) and the water-insoluble polysaccharide polymer fiber (E) and mixed. And a method of adding and mixing the water-soluble polymer (D) dissolved in a solvent to the mixture.

  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. The mixing is preferably performed at 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 nozzle system. In the rotating disk system, slurry is introduced almost at the center of the disk that rotates at high speed, and the slurry is released outside 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 preferably 5,000 to 30,000 rpm, more preferably 15,000 to 30,000 rpm. The lower the rotational speed of the disk, the larger the spray droplets and the larger the average particle size of the resulting composite particles. 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 nozzle method is a method in which the slurry for composite particles is pressurized to form a mist from the nozzle and dried, or the slurry ejected from the nozzle is formed into a mist by air pressure and dried.

  The temperature of the slurry for composite particles to be sprayed is preferably room temperature, but may be heated to a temperature higher than room temperature. Moreover, the hot air temperature 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 80-150 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.

(Electrochemical element electrode)
An electrochemical element electrode (positive electrode) can be obtained by laminating a positive electrode active material layer containing the composite particles for an electrochemical element electrode of the present invention on a current collector. As a material for the current collector, 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 preferably 1 to 200 μm, more preferably 5 to 100 μm, and still more preferably 10 to 50 μm.

  When laminating the positive electrode active material layer on the current collector, the composite particles may be formed into a sheet shape and then laminated on the current collector, but the composite particles are directly pressure-molded on the current collector. Is preferred. As a method for pressure molding, for example, a roll type pressure molding apparatus provided with a pair of rolls is used, and a roll type pressure molding apparatus is used to feed composite particles with a feeder such as a screw feeder while feeding a current collector with the roll. By supplying to the roll pressure forming method for forming the positive electrode active material layer on the current collector, and dispersing the composite particles on the current collector, adjusting the thickness by smoothing the composite particles with a blade, Next, a method of forming with a pressurizing apparatus, a method of filling composite particles into a mold, and pressurizing the mold to form are included. Among these, the roll pressure molding method is preferable. In particular, since the composite particles of the present invention have high fluidity, they can be molded by roll press molding due to the high fluidity, thereby improving productivity.

  The roll temperature at the time of roll pressing is preferably 25 to 200 ° C., more preferably 50 to 150 ° C., from the viewpoint of ensuring sufficient adhesion between the positive electrode active material layer and the current collector. More preferably, it is 80-120 degreeC. Moreover, the press linear pressure between rolls at the time of roll press molding is preferably 10 to 1000 kN / m, more preferably 200 to 900 kN / m, from the viewpoint of improving the uniformity of the thickness of the positive electrode active material layer. More preferably, it is 300-600 kN / m. 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 variations in the thickness of the formed electrochemical element electrode (positive electrode) and increase the density of the positive electrode active material layer to increase the capacity. The post-pressing method is preferably a pressing process using a roll. In the roll pressing step, two cylindrical rolls are arranged vertically in parallel with a narrow interval, each is rotated in the opposite direction, and pressure is applied by interposing an electrode therebetween. In this case, the temperature of the roll may be adjusted as necessary, such as heating or cooling.

(Electrochemical element)
An electrochemical element can be obtained by using the electrochemical element electrode obtained as described above as a positive electrode and further including a negative electrode, a separator, and an electrolytic solution. Examples of the electrochemical element include a lithium ion secondary battery and a lithium ion capacitor.

(Negative electrode)
The negative electrode of an electrochemical element is formed by laminating a negative electrode active material layer on a current collector. The negative electrode of the electrochemical device collects a negative electrode slurry containing a negative electrode active material, a binder resin for the negative electrode, a solvent used for preparing the negative electrode, a water-soluble polymer used as necessary, and other components such as a conductive agent. It can be obtained by applying to the surface of the body and drying. That is, the negative electrode active material layer is formed on the current collector by applying the slurry for the negative electrode to the surface of the current collector and drying it.

(Negative electrode active material)
Examples of the negative electrode active material when the electrochemical device of the present invention is a lithium ion secondary battery include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microbeads, pitch-based carbon fibers; Conductive polymers; metals such as silicon, tin, zinc, manganese, iron, nickel or alloys thereof; oxides or sulfates of the metals or alloys; metal lithium; Li-Al, Li-Bi-Cd, Li- Examples thereof include lithium alloys such as Sn—Cd; lithium transition metal nitrides; silicon and the like. Further, as the negative electrode active material, a material obtained by attaching a conductive agent to the surface of the negative electrode active material particles by, for example, a mechanical modification method may be used. Moreover, a negative electrode active material may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The particle diameter of the particles of the negative electrode active material is usually selected as appropriate in consideration of other components of the electrochemical element. Among these, from the viewpoint of improving battery characteristics such as initial efficiency, load characteristics, and cycle characteristics, the 50% volume cumulative diameter of the particles of the negative electrode active material is preferably 1 to 50 μm, more preferably 15 to 30 μm.

The content of the negative electrode active material in the negative electrode active material layer can increase the capacity of the lithium ion secondary battery, and improve the flexibility of the negative electrode and the binding property between the current collector and the negative electrode active material layer. From the viewpoint of being able to achieve the above, it is preferably 90 to 99.9% by weight, more preferably 95 to 99% by weight.
Moreover, as a negative electrode active material preferably used when an electrochemical element is a lithium ion capacitor, the negative electrode active material formed with the said carbon is mentioned.

(Binding resin for negative electrode)
As the negative electrode binder resin, for example, the same binder resin as that used in the positive electrode active material layer may be used. Further, for example, resins such as polyethylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyacrylic acid derivatives, polyacrylonitrile derivatives; acrylic soft polymers, diene soft polymers, olefin soft polymers, Examples thereof include soft polymers such as vinyl-based soft polymers. In addition, a binder resin may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

(Other ingredients)
As the water-soluble polymer and conductive agent used in the negative electrode slurry as necessary, the water-soluble polymer and conductive agent that can be used for the composite particles described above can be used.

(Solvent used for preparation of negative electrode)
As a solvent used for producing the negative electrode, either water or an organic solvent may be used. Examples of the organic solvent include cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ketones such as ethyl methyl ketone and cyclohexanone; ethyl acetate, butyl acetate, and γ-butyrolactone Esters such as ε-caprolactone; alkyl nitriles such as acetonitrile and propionitrile; ethers such as tetrahydrofuran and ethylene glycol diethyl ether: alcohols such as methanol, ethanol, isopropanol, ethylene glycol, and ethylene glycol monomethyl ether; N Amides such as -methylpyrrolidone and N, N-dimethylformamide; among them, N-methylpyrrolidone (NMP) is preferred. In addition, a solvent may be used individually by 1 type and may be used combining two or more types by arbitrary ratios. Of these, water is preferably used as the solvent.

  What is necessary is just to adjust the quantity of a solvent so that the viscosity of the slurry for negative electrodes may become a viscosity suitable for application | coating. Specifically, the solid content concentration of the negative electrode slurry is preferably adjusted to 30 to 90% by weight, more preferably 40 to 80% by weight.

(Current collector)
As the current collector used for the negative electrode, the same current collector as the current collector used for the electrochemical element electrode (positive electrode) can be used.

(Method for producing negative electrode)
The method for applying the negative electrode slurry to the surface of the current collector is not particularly limited. Examples of the method include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method.

  Examples of the drying method include drying with warm air, hot air, and low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams. The drying time is preferably 5 to 30 minutes, and the drying temperature is preferably 40 to 180 ° C.

In addition, after applying and drying the negative electrode slurry on the surface of the current collector, the negative electrode active material layer is preferably subjected to pressure treatment using, for example, a die press or a roll press as necessary. By the pressure treatment, the porosity of the negative electrode active material layer can be lowered. The porosity is preferably 5% or more, more preferably 7% or more, preferably 30% or less, more preferably 20% or less. When the porosity is too small, it is difficult to obtain a high volume capacity, and the negative electrode active material layer is easily peeled off from the current collector. On the other hand, when the porosity is too large, the charging efficiency and the discharging efficiency are lowered.
Furthermore, when the negative electrode active material layer contains a curable polymer, it is preferable to cure the polymer after the formation of the negative electrode active material layer.

(separator)
As the separator, for example, a polyolefin resin such as polyethylene or polypropylene, or a microporous film or nonwoven fabric containing an aromatic polyamide resin; a porous resin coat containing an inorganic ceramic powder; Specific examples include microporous membranes made of polyolefin resins (polyethylene, polypropylene, polybutene, polyvinyl chloride), and resins such as mixtures or copolymers thereof; polyethylene terephthalate, polycycloolefin, polyether sulfone, polyamide, Examples thereof include a microporous film made of a resin such as polyimide, polyimide amide, polyaramid, nylon, and polytetrafluoroethylene; a polyolefin fiber woven or non-woven fabric thereof; and an aggregate of insulating substance particles. Among these, since the film thickness of the entire separator can be reduced and the active material ratio in the lithium ion secondary battery can be increased to increase the capacity per volume, a microporous film made of polyolefin resin is used. preferable.

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

(Electrolyte)
As an electrolytic solution for a lithium ion secondary battery, for example, a nonaqueous electrolytic solution in which a supporting electrolyte is dissolved in a nonaqueous solvent is used. As the supporting electrolyte, a lithium salt is preferably used. Examples of the lithium salt include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi , (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ ) NLi, and the like. Among these, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li that are easily soluble in a solvent and exhibit a high degree of dissociation are preferable. One of these may be used alone, or two or more of these may be used in combination at any ratio. Since the lithium ion conductivity increases as the supporting electrolyte having a higher degree of dissociation is used, the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.

  The concentration of the supporting electrolyte in the electrolytic solution is preferably used at a concentration of 0.5 to 2.5 mol / L depending on the type of the supporting electrolyte. If the concentration of the supporting electrolyte is too low or too high, the ionic conductivity may decrease.

  The non-aqueous solvent is not particularly limited as long as it can dissolve the supporting electrolyte. Examples of non-aqueous solvents include carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), methyl ethyl carbonate (MEC); Examples include 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; and ionic liquids used also as supporting electrolytes. Among these, carbonates are preferable because they have a high dielectric constant and a wide stable potential region. A non-aqueous 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, but since both are in a trade-off relationship, the lithium ion conductivity depends on the type of solvent and the mixing ratio. It is recommended to adjust the conductivity. In addition, the nonaqueous solvent may be used in combination or in whole or in a form in which all or part of hydrogen is replaced with fluorine.

Moreover, you may contain an additive in electrolyte solution. Examples of the additive include carbonates 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.
In addition, as an electrolyte solution for lithium ion capacitors, the same electrolyte solution that can be used for the above-described lithium ion secondary battery can be used.

(Method for producing electrochemical element)
As a specific method for producing an electrochemical element such as a lithium ion secondary battery or a lithium ion capacitor, for example, a positive electrode and a negative electrode are overlapped via a separator, and this is wound or folded according to the shape of the battery. Examples of the method include putting the battery in a battery container, injecting an electrolyte into the battery container, and sealing the battery. Further, if necessary, an expanded metal; an overcurrent prevention element such as a fuse or a PTC element; a lead plate or the like may be inserted to prevent an increase in pressure inside the battery or overcharge / discharge. The shape of the lithium ion secondary battery may be any of a coin type, a button type, a sheet type, a cylindrical type, a square type, a flat type, and the like. The material of the battery container is not particularly limited as long as it inhibits the penetration of moisture into the battery, and is not particularly limited, such as a metal or a laminate such as aluminum.

  According to the composite particle for an electrochemical element electrode of the present invention, an electrode having sufficient strength, excellent uniformity, sufficient adhesion when forming an electrode, and excellent flexibility Can be obtained. Moreover, the composite particle for electrochemical element electrodes of the present invention has excellent fluidity.

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

  In Examples and Comparative Examples, evaluation of particle strength of composite particles, uniformity of active material and conductive agent of composite particles, peel strength, flexibility, and cycle characteristics was performed as follows. Moreover, in the following, an average fiber diameter is an average value when a fiber diameter is measured about 100 water-insoluble polysaccharide polymer fibers in the visual field of an electron microscope.

<Particle strength of composite particles>
The composite particles obtained in Examples and Comparative Examples were subjected to a compression test using a micro compression tester (“MCT-W500” manufactured by Shimadzu Corporation). In the compression test, a compressive strength (MPa) is measured when a particle is deformed until the diameter of the composite particle is displaced by 40% by applying a load at a loading speed of 4.46 mN / sec in the center direction of the composite particle at room temperature. did. In this measurement, a composite particle having a diameter of 40 to 60 μm was selected and a compression test was performed.

Further, the compression test was performed 10 times, and the average value was set as the compression strength. The compressive strength was evaluated according to the following criteria, and the results are shown in Tables 1 and 2. In addition, it shows that it is excellent in the adhesive strength of positive electrode active materials, and a composite particle is excellent in particle strength, so that compressive strength is large.
A: Compressive strength is 1.00 MPa or more B: Compressive strength is 0.90 MPa or more and less than 1.00 MPa C: Compressive strength is 0.80 MPa or more and less than 0.90 MPa D: Compressive strength is 0.70 MPa or more, 0.80 MPa Less than E: Compressive strength is less than 0.70 MPa

<Uniformity of composite particle active material and conductive agent>
A carbon tape (aluminum substrate) cut to 10 mm × 10 mm was pasted on a sample stand of FE-SEM, and one micro spatula was placed thereon so that the composite particles did not overlap. Thereafter, a cellophane tape cut to 13 mm × 13 mm was carefully attached so as to cover the entire carbon tape, and then the cellophane tape was carefully peeled off so that the carbon tape was not peeled off. With 20 FE-SEM (S-4700 accelerating voltage 1.0 kV, manufactured by Hitachi High-Technologies Corporation), 20 active composite particles having a particle size of 38 to 42 μm, which are finely sectioned at the center of the particle, are connected to the active material. Observations were made regarding agent uniformity. Note that composite particles having small and large particle diameters and composite particles that are not clearly sectioned were excluded.
A: Active material and conductive agent are present uniformly throughout the particle B: Active material and conductive agent are present substantially uniformly throughout the particle C: Part of the conductive agent is localized on the particle surface D: Conductive agent is on the particle surface Localized to

<Peel strength>
The positive electrodes for lithium ion secondary batteries obtained in the examples and comparative examples were cut into a rectangular shape having a width of 1 cm and a length of 10 cm. After fixing the cut positive electrode for a lithium ion secondary battery with the positive electrode active material layer face up, and applying a cellophane tape on the surface of the positive electrode active material layer, the cellophane tape is applied at a speed of 50 mm / min from one end of the test piece. The stress when peeled in the 180 ° direction was measured. This stress was measured 10 times, and the average value was defined as the peel strength. The peel strength was evaluated according to the following criteria, and the results are shown in Tables 1 and 2. In addition, it shows that the adhesiveness in a positive electrode active material layer and the adhesiveness between a positive electrode active material layer and a collector are so favorable that peel strength is large.
A: Peel strength is 15 N / m or more B: Peel strength is 7 N / m or more and less than 15 N / m C: Peel strength is 3 N / m or more and less than 7 N / m D: Peel strength is less than 3 N / m E: Unevaluable

<Electrode flexibility>
A rod having a different diameter is placed on the positive electrode active material layer side of the positive electrode for lithium ion secondary batteries obtained in the examples and comparative examples, and the positive electrode is wound around the rod to evaluate whether the positive electrode active material layer is cracked. The results are shown in Tables 1 and 2. It shows that it is excellent in the winding property of a positive electrode, so that the diameter of a stick | rod is small. When the winding property is excellent, peeling of the positive electrode active material layer can be suppressed, and thus the cycle characteristics of the secondary battery are excellent.
A: Unbreakable at 1.2 mmφ B: Unbreakable at 1.5 mmφ C: Unbreakable at 2 mmφ D: Unbreakable at 3 mmφ E: Unbreakable at 4 mmφ

<Charge / discharge cycle characteristics>
The laminate-type lithium ion secondary batteries obtained in the examples and comparative examples were charged at a constant current until reaching 4.2 V by a constant current constant voltage charging method of 0.5 C at 60 ° C. A charge / discharge cycle test was performed in which the battery was charged with a voltage and then discharged to 3.0 V at a constant current of 0.5C. The charge / discharge cycle test was conducted up to 100 cycles, and the ratio of the discharge capacity at the 100th cycle to the initial discharge capacity was defined as the capacity retention rate. The capacity retention rate was evaluated according to the following criteria, and the results are shown in Tables 1 and 2. It shows that the capacity | capacitance maintenance factor is so large that there is little decrease in the capacity | capacitance by repeated charging / discharging.
A: Capacity maintenance ratio is 90% or more B: Capacity maintenance ratio is 80% or more and less than 90% C: Capacity maintenance ratio is 75% or more and less than 80% D: Capacity maintenance ratio is 70% or more and less than 75% E: Capacity maintenance rate is less than 70% or cannot be evaluated

[Example 1]
(Production of particulate binder resin (C))
To a 1 L SUS separable flask equipped with a stirrer, a reflux condenser and a thermometer, add 130 parts of ion exchange water, and further add 0.8 parts of ammonium persulfate and 10 parts of ion exchange water as a polymerization initiator. , Heated to 80 ° C.

  In another container with a stirrer, 76 parts of 2-ethylhexyl acrylate as a (meth) acrylic acid ester monomer, 20 parts of acrylonitrile as an α, β-unsaturated nitrile monomer, an acidic functional group-containing monomer As an emulsifier, 4.0 parts of itaconic acid, 2.0 parts of sodium dodecylbenzenesulfonate as an emulsifier and 377 parts of ion-exchanged water were added and sufficiently stirred to prepare an emulsion.

  The emulsion obtained above was continuously added to the separable flask over 3 hours. After further reaction for 2 hours, the reaction was stopped by cooling. 10% aqueous ammonia was added thereto to adjust the pH to 7.5 to obtain an aqueous dispersion of the particulate binder resin (C) (acrylate polymer). The polymerization conversion rate was 98%.

(Manufacture of slurry for composite particles)
90.8 parts of LiCoO ₂ (hereinafter sometimes abbreviated as “LCO”) having a layered structure as the positive electrode active material (A) and acetylene black (hereinafter abbreviated as “AB”) as the conductive agent (B). May be abbreviated as carboxymethyl cellulose (hereinafter referred to as “CMC”) as the water-soluble polymer (D). 1) aqueous solution (BSH-12; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in 0.7 parts in terms of solid content, and 2% water dispersion of cellulose nanofiber as water-insoluble polysaccharide polymer fiber (E) 1 part of the liquid (BiNFi-s (NMa-120002), raw material: conifer, average polymerization degree: 500; manufactured by Sugino Machine Co., Ltd.) is mixed in an amount equivalent to the solid content, and ion-exchanged water has a solid content concentration of 50%. As well as planetary Mixture to obtain a slurry for composite particles Kisa.

(Manufacture of composite particles)
The slurry for composite particles in a spray dryer (manufactured by Okawara Kako Co., Ltd.) was used with a rotary disk type atomizer (diameter 65 mm), rotation speed 25,000 rpm, hot air temperature 150 ° C., and particle recovery outlet temperature 90 ° C. Then, spray drying granulation was performed to obtain composite particles. The composite particles had an average volume particle diameter of 40 μm.

(Manufacture of positive electrodes for lithium ion secondary batteries)
The composite particles obtained above are used for a press roll (roll temperature) of a roll press machine (“Hirano Giken Kogyo Co., Ltd.“ Rough Surface Heated Roll ”) using a quantitative feeder (“ Nikka Spray K-V ”manufactured by Nikka). 100 ° C., press linear pressure 500 kN / m). An aluminum foil having a thickness of 20 μm is inserted between the press rolls, the composite particles supplied from the quantitative feeder are adhered onto the aluminum foil, pressure-molded at a molding speed of 1.5 m / min, and lithium ion secondary A positive electrode for a battery was obtained.

(Manufacture of binder resin for negative electrodes)
In a 5 MPa pressure vessel with a stirrer, 47 parts of styrene, 50 parts of 1,3-butadiene, 3 parts of methacrylic acid, 4 parts of sodium dodecylbenzenesulfonate, 150 parts of ion-exchanged water, 0.4 part of t-dodecyl mercaptan as a chain transfer agent Then, 0.5 part of potassium persulfate was added as a polymerization initiator, and after sufficiently stirring, the mixture was heated to 50 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a particulate negative electrode binder resin (styrene / butadiene copolymer; hereinafter abbreviated as “SBR”). It was.

(Manufacture of slurry for negative electrode)
In a planetary mixer with a disper, 98.3 parts of artificial graphite (average particle size: 24.5 μm) having a specific surface area of 4 m ² / g as a negative electrode active material and a 1% aqueous solution of carboxymethyl cellulose (BSH-12; No. 1) as a dispersant Made by Ichi Kogyo Seiyaku Co., Ltd.) 0.7 part in solid content and 1.0 part in negative electrode binder resin in solid content, and adjusted to 50% total solids with ion-exchanged water. And mixed. This was defoamed under reduced pressure to obtain a slurry for the negative electrode.

(Manufacture of negative electrodes for lithium ion secondary batteries)
The negative electrode slurry obtained above was applied onto a copper foil having a thickness of 20 μm using a comma coater so that the dried film thickness was about 150 μm and dried. This drying was performed by conveying the copper foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Thereafter, heat treatment was performed at 120 ° C. for 2 minutes to obtain a negative electrode raw material. This negative electrode raw material was rolled with a roll press to obtain a negative electrode for a lithium ion secondary battery.

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

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

[Example 2]
Production of composite particle slurry, production of composite particles, production of positive electrode for lithium ion secondary battery, lithium ion, as in Example 1, except that 90.8 parts of LiNiO ₂ was used as the positive electrode active material (A) A secondary battery was manufactured.

[Example 3]
Production of slurry for composite particles and production of composite particles in the same manner as in Example 1 except that 90.8 parts of nickel manganese cobaltate (NMC (111)) having a layered structure was used as the positive electrode active material (A). Then, a positive electrode for a lithium ion secondary battery and a lithium ion secondary battery were manufactured.

[Example 4]
Carried out except that cellulose nanofiber 1.2% aqueous dispersion (raw material: bamboo, degree of defibration: high, average degree of polymerization: 350; manufactured by Chuetsu Pulp Co., Ltd.) was used as the water-insoluble polysaccharide polymer fiber (E). In the same manner as in Example 1, production of a slurry for composite particles, production of composite particles, production of a positive electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery were performed.

[Example 5]
Implemented except that cellulose nanofiber 1.1% aqueous dispersion (raw material: hardwood, defibration degree: low, average degree of polymerization: 600; manufactured by Chuetsu Pulp Co., Ltd.) was used as the water-insoluble polysaccharide polymer fiber (E). In the same manner as in Example 1, production of a slurry for composite particles, production of composite particles, production of a positive electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery were performed.

[Example 6]
Example 1 with the exception that a 10% aqueous dispersion of cotton cellulose nanofibers (fiber diameter 0.1-0.01 μm, serisch KY100G; manufactured by Daicel Finechem) was used as the water-insoluble polysaccharide polymer fiber (E). Similarly, production of a slurry for composite particles, production of composite particles, production of a positive electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery were performed.

[Example 7]
Example 1 except that a 2% aqueous dispersion of chitin nanofibers (BiNFi-s (SFo-120002), average polymerization degree: 300; manufactured by Sugino Machine Co., Ltd.) was used as the water-insoluble polysaccharide polymer fiber (E). In the same manner as above, production of a slurry for composite particles, production of composite particles, production of a positive electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery were performed.

[Example 8]
Example 1 except that a 2% aqueous dispersion of chitosan nanofibers (BiNFi-s (EFo-120002), average degree of polymerization: 480; manufactured by Sugino Machine Co., Ltd.) was used as the water-insoluble polysaccharide polymer fiber (E). In the same manner as above, production of a slurry for composite particles, production of composite particles, production of a positive electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery were performed.

[Example 9]
As a water-soluble polymer (D), 0.5 part of a 1% aqueous solution of carboxymethyl cellulose (BSH-12; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is mixed as a water-soluble polymer to obtain a water-insoluble polysaccharide polymer fiber (E). 2% aqueous dispersion of cellulose nanofiber (BiNFi-s (NMa-120002), raw material: conifer, average degree of polymerization: 500; manufactured by Sugino Machine Co., Ltd.) was mixed except 1.2 parts in terms of solid content. In the same manner as in Example 1, a slurry for composite particles was produced. Thereafter, the production of composite particles, the production of a positive electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1.

[Example 10]
When obtaining the composite particle slurry, 90.2 parts of LCO as the positive electrode active material (A), 6 parts of acetylene black as the conductive agent (B), 1.5 parts of the particulate binder resin (C), water-soluble As polymer (D), 1 part of CMC aqueous solution (BSH-6; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is 2.0 parts in terms of solid content, and 2 of cellulose nanofiber as water-insoluble polysaccharide polymer fiber (E) % Aqueous dispersion (BiNFi-s (NMa-120002), raw material: conifer, average degree of polymerization: 500; manufactured by Sugino Machine Co., Ltd.) is the same as Example 1 except that 0.3 parts in terms of solid content is mixed. A slurry for composite particles was produced. Thereafter, the production of composite particles, the production of a positive electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1.

[Example 11]
As the water-soluble polymer (D), except that a polyacrylic resin was used, the production of the composite particle slurry, the production of the composite particle, the production of the positive electrode for the lithium ion secondary battery, the lithium ion secondary, as in Example 1. The battery was manufactured. The polyacrylic resin was produced as follows.

(Manufacture of polyacrylic resin)
Into a 1 L SUS separable flask equipped with a stirrer, a reflux condenser and a thermometer, demineralized water was charged in advance and stirred sufficiently, and then the temperature was adjusted to 70 ° C., and 0.2 part of an aqueous potassium persulfate solution was added.

  In another 5 MPa pressure vessel with a stirrer, 50 parts of ion-exchanged water, 0.4 part of sodium hydrogen carbonate, 0.115 part of sodium dodecyl diphenyl ether sulfonate having a concentration of 30% as an emulsifier, 60 parts of methacrylic acid, ethyl 15 parts of acrylate and 15 parts of butyl acrylate, and a monomer mixture composed of 10 parts of 2-acrylamido-2-methylpropanesulfonic acid as a sulfonic acid group-containing monomer copolymerizable therewith and stirred sufficiently An aqueous emulsion was prepared.

  The obtained emulsion aqueous solution was continuously dripped over 4 hours to the said separable flask. When the polymerization conversion rate reached 90%, the reaction temperature was set to 80 ° C., and the reaction was further carried out for 2 hours. Then, the reaction was stopped by cooling to obtain an aqueous dispersion containing a polyacrylic resin. The polymerization conversion rate was 99%. Moreover, it was 25000 when the weight average molecular weight of the obtained polyacrylic resin was measured by GPC. Moreover, the viscosity when the obtained polyacrylic resin was made into 1 weight% aqueous solution was 3000 (mPa * s).

[Example 12]
As the water-soluble polymer (D), except that poly-N-vinylacetamide (PNVA, GE191-103; manufactured by Showa Denko KK) resin was used, production of a slurry for composite particles, Production, production of a positive electrode for a lithium ion secondary battery, and production of a lithium ion secondary battery were carried out.

[Example 13]
Manufacture of slurry for composite particles, manufacture of composite particles, lithium as in Example 1 except that polyvinyl alcohol resin (PVA, JF-17; manufactured by Nihon Vinegar Bipoval) was used as the water-soluble polymer (D). Production of a positive electrode for an ion secondary battery and production of a lithium ion secondary battery were carried out.

[Comparative Example 1]
When cellulose nanofibers as water-insoluble polysaccharide polymer fibers (E) are not added and a slurry for composite particles is obtained, 91 parts of LCO as the positive electrode active material (A) and 6 parts of acetylene black as the conductive agent (B) 1 part aqueous solution of CMC (BSH-12; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a solid content in an amount of 1.5 parts by weight, 1.5 parts of the particulate binder resin (C) and the water-soluble polymer (D). A slurry for composite particles was produced in the same manner as in Example 1 except that each part was mixed. Thereafter, the production of composite particles, the production of a positive electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1.

[Comparative Example 2]
CMC is not added as the water-soluble polymer (D), and when obtaining a slurry for composite particles, 91.0 parts of LCO as the positive electrode active material (A), 6 parts of acetylene black as the conductive agent (B), particulate form 1.5 parts of binder resin (C) and water-insoluble polysaccharide polymer fiber (E) as a 2% aqueous dispersion of cellulose nanofibers (BiNFi-S (NMa-120002), average polymerization degree 500; Sugino Machine Co., Ltd. The slurry for composite particles was produced in the same manner as in Example 1 except that 1.5 parts of each product was mixed in terms of solid content. Thereafter, the production of composite particles, the production of a positive electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1.

[Comparative Example 3]
When obtaining the composite particle slurry, 90.7 parts of LCO as the positive electrode active material (A), 6 parts of acetylene black as the conductive agent (B), 1.5 parts of the particulate binder resin (C), water-soluble As a polymer (D), a 1% aqueous solution of CMC (BSH-12; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is 0.3 parts in terms of solid content, and cellulose nanofiber 2 is used as a water-insoluble polysaccharide polymer fiber (E). A slurry for composite particles in the same manner as in Example 1 except that 1.5 parts of an aqueous dispersion (BiNFi-S (NMa-120002), average polymerization degree 500; manufactured by Sugino Machine Co., Ltd.) was mixed in an amount of 1.5 parts in terms of solid content. Was manufactured. Thereafter, the production of composite particles, the production of a positive electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1.

[Comparative Example 4]
When obtaining the composite particle slurry, 91.4 parts of LCO as the positive electrode active material (A), 6 parts of acetylene black as the conductive agent (B), 1.5 parts of the particulate binder resin (C), water-soluble 1.0 part of 1% aqueous solution of CMC (BSH-12; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as the polymer (D), and 2 parts of cellulose nanofiber as the water-insoluble polysaccharide polymer fiber (E) A slurry for composite particles in the same manner as in Example 1 except that 0.1 part of an aqueous dispersion (BiNFi-S (NMa-120002), average polymerization degree 500; manufactured by Sugino Machine Co., Ltd.) was mixed in an amount of 0.1 part in terms of solid content. Was manufactured. Thereafter, the production of composite particles, the production of a positive electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1.

[Comparative Example 5]
In place of the water-insoluble polysaccharide polymer fiber (E), carbon nanofibers (VGCF: manufactured by Showa Denko KK, fiber diameter 150 nm, fiber length 20 μm) are used as reinforcing fibers to obtain a positive electrode active 90.8 parts of LCO as substance (A), 6 parts of acetylene black as conductive agent (B), 1.5 parts of particulate binder resin (C), 1% of CMC as water-soluble polymer (D) Production of slurry for composite particles in the same manner as in Example 1, except that 0.7 part of an aqueous solution (BSH-12; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 1.0 part of carbon nanofiber were mixed. Went. Thereafter, the production of composite particles, the production of a positive electrode for a lithium ion secondary battery, and the production of a lithium ion secondary battery were carried out in the same manner as in Example 1.

  As shown in Tables 1 and 2, the positive electrode active material (A), the conductive agent (B), the particulate binder resin (C), the water-soluble polymer (D), and the water-insoluble polysaccharide polymer fiber (E) A composite particle for an electrochemical element electrode comprising: a water-soluble polymer (D) and a water-insoluble polysaccharide polymer fiber (E) in a weight ratio of (D) / (E) = 0.25 The particle strength of the composite element electrode for electrochemical device contained at a ratio of 7.0 was good. Moreover, the uniformity of the positive electrode active material (A) and the conductive agent (B) of the composite particles was good. Moreover, the peel strength and electrode flexibility of the positive electrode obtained using this composite particle were good. Furthermore, the charge / discharge cycle characteristics of the lithium ion secondary battery obtained using the composite particles were good.

Claims (4)

A composite particle for an electrochemical element electrode comprising a positive electrode active material (A), a conductive agent (B), a particulate binder resin (C), a water-soluble polymer (D) and a water-insoluble polysaccharide polymer fiber (E) There,
The water-soluble polymer (D) and the water-insoluble polysaccharide polymer fiber (E) are included in a weight ratio of (D) / (E) = 0.25 to 7.0. Composite particles for electrochemical device electrodes.   2. The composite particle for an electrochemical element electrode according to claim 1, wherein the water-insoluble polysaccharide polymer fiber (E) has an average polymerization degree of 50 to 1,000.   The composite particle for an electrochemical element electrode according to claim 1 or 2, wherein the particulate binder resin (C) is an acrylate polymer. The amount of the water-soluble polymer (D) is 0.1 to 10 parts by weight in terms of solid content with respect to 100 parts by weight of the positive electrode active material (A),
The amount of the water-insoluble polysaccharide polymer fiber (E) is 0.1 to 2 parts by weight in terms of solid content with respect to 100 parts by weight of the composite particles obtained. The composite particle for an electrochemical element electrode according to any one of the above.