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  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/24—Electrically-conducting paints
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
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  • C08F220/44—Acrylonitrile
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  • C08F226/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
  • C08F226/06—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen
  • C08F226/10—N-Vinyl-pyrrolidone
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  • C09D201/00—Coating compositions based on unspecified macromolecular compounds
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  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
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  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
  • C09K23/017—Mixtures of compounds
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  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
  • C09K23/52—Natural or synthetic resins or their salts
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/20—Conductive material dispersed in non-conductive organic material
  • H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/32—Carbon-based
  • H01G11/38—Carbon pastes or blends; Binders or additives therein
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/50—Electrodes characterised by their material specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/001—Conductive additives
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  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • H—ELECTRICITY
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  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/32—Carbon-based
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• An embodiment of the present invention relates to a conductive material dispersion, a coating film using the same, and a secondary battery.
• conductive materials have been actively developed to impart functions such as antistatic property, conductivity, thermal conductivity, and electromagnetic wave shielding property to various materials and to be applied to various uses.
• a carbon-based conductive material is widely used because of its high heat resistance, light resistance, corrosion resistance, light weight and relatively low cost, and high conductivity. ..
• a method of kneading the conductive material into a base material such as plastic or glass can be used.
• the mainstream method is to disperse the conductive material in a wet manner and mix it with various materials as needed for coating.
• the conductive material is required to exhibit high conductivity in a small amount so as not to deteriorate other application characteristics such as optical characteristics, design characteristics, and electrical characteristics. Therefore, it is effective to use a carbon-based conductive material having a large specific surface area, particularly carbon black (hereinafter CB) or carbon nanotube (hereinafter CNT).
• CB carbon black
• CNT carbon nanotube
• Patent Document 1 and Patent Document 2 each propose a conductive material dispersion in which a dispersant is dispersed in an aqueous medium.
• a dispersant polyvinylpyrrolidone or polyvinyl alcohol is used as a dispersant.
• Patent Document 2 a polymer having polyacrylonitrile as a main skeleton is used as a dispersant. If an efficient conductive network can be formed by using these dispersants, it is expected that the initial characteristics or the cycle life will be improved when a conductor dispersion is prepared and used for a secondary battery, for example.
• foaming is likely to occur when the dispersoid is dispersed in a medium containing water.
• various problems are likely to occur. For example, air bubbles interfere with the wetting of the dispersoid, and the chargeability and dispersibility tend to deteriorate.
• the energy of the disperser is consumed for the miniaturization of bubbles, and the dispersion tends to be stopped. As a result, it becomes impossible to form an efficient conductive network as described above.
• a type of disperser such as a high-pressure homogenizer that miniaturizes the dispersoid by pressure, the entry of air bubbles poses a risk of explosion, nozzle clogging, or equipment damage. Therefore, in order to solve such a problem, an antifoaming agent has often been used when the dispersion medium contains water.
• Patent Document 3 discloses that the residue of a low molecular weight organic compound having an unsaturated bond, which is generated when synthesizing a polymer of acrylonitrile and butadiene, affects the battery characteristics. Specifically, when a polymer containing the above residue is used for the negative electrode, the residue dissolves in the electrolytic solution and moves to the positive electrode side, and the unsaturated bond causes an oxidation reaction, resulting in deterioration of battery performance. By reducing the residue of low molecular weight organic compounds having unsaturated bonds, the deterioration of battery performance is solved.
• Patent Document 4 when a binder composition containing an acrylic polymer is used for an electrode slurry, the monomer for forming the polymer by polymerization and the monomer react with each other. It has been found that the oligomer is adsorbed on the active material and the dispersion stability is lowered, and a method for solving the deterioration of the battery performance by reducing the amounts of the monomer and the oligomer is proposed.
• the acrylic polymer is used in a state of being dispersed in a medium by an emulsifier.
• the components derived from the raw material of the dispersant (polymer) are eluted in the electrolytic solution in the battery to increase the viscosity of the electrolytic solution and increase the diffusion resistance of the electrolyte ions, or decrease the dielectric constant of the electrolytic solution solvent. It has been clarified that either or both of the phenomena of lowering the conductivity of the electrolytic solution are caused at the same time, and the ionic resistance is deteriorated, and as a result, various characteristics of the battery are deteriorated. According to a detailed investigation by the present inventors, it was found that the output of a battery having a poor ion resistance is significantly deteriorated because the ion resistance becomes dominant, especially at a low temperature.
• the component derived from the raw material of the dispersant described above has a structure having a relatively high oxidation resistance.
• one embodiment of the present invention provides a conductive material dispersion with less foaming. Further, one embodiment of the present invention provides a secondary battery having low electronic resistance and ionic resistance and good low temperature characteristics.
• a specific polymer is contained as a dispersant, and the amount of the component derived from the raw material of the specific polymer is suppressed to a certain level or less, so that the defoaming agent is not added or a very small amount is added. It has become possible to provide a secondary battery capable of satisfactorily dispersing the conductive material, improving the electronic resistance, and further improving the low temperature characteristics. In addition, it has become possible to provide a conductive material dispersion capable of forming an efficient conductive network that can realize excellent characteristics not only in a secondary battery but also in various applications.
• the present invention includes the following embodiments.
• the embodiments of the present invention are not limited to the following.
• One embodiment of the present invention relates to a conductive material dispersion containing a dispersant satisfying the following (1) and (2), a carbon-based conductive material (C), and a medium (D) containing at least water.
• a conductive material dispersion containing a dispersant satisfying the following (1) and (2), a carbon-based conductive material (C), and a medium (D) containing at least water.
• It has at least one selected from the group consisting of a nitrile group-containing structural unit, a carboxyl group-containing structural unit, a hydroxyl group-containing structural unit, and a heterocycle-containing structural unit, and has a weight average molecular weight of 5,000 or more and 360.
• the component (B) other than the polymer derived from the raw material of the polymer (A) is contained in an amount of 2% by mass or less based on the mass of the dispersant.
• the polymer (A) contains 5% by mass or less of the polymer (E) having a molecular weight of less than 1,000 based on the total mass of the polymer (A). You may.
• the conductive material dispersion preferably has a complex elastic modulus of 5 Pa or more and less than 650 Pa at 25 ° C. and 1 Hz as measured by dynamic viscoelasticity.
• the conductive material dispersion preferably has a phase angle of 3 ° or more and less than 60 ° at 25 ° C and 1 Hz as measured by dynamic viscoelasticity.
• the conductive material dispersion further contains a binder.
• the conductive material dispersion further contains an electrode active material.
• One embodiment relates to a coating film using the conductive material dispersion of the above embodiment.
• One embodiment relates to a secondary battery including the coating film of the above embodiment.
• the disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2020-206803 filed on December 14, 2020 and Japanese Patent Application No. 2021-133770 filed on August 19, 2021, all of which. The disclosure content of is incorporated here by citation.
• a conductive material dispersion having less foaming. Further, it is possible to provide a secondary battery having good rate characteristics and cycle characteristics, low electronic resistance and ionic resistance, and good low temperature characteristics.
• a dispersant composition containing a polymer (A) and a component (B) other than the polymer derived from the raw material of the polymer (A) will be described. Further, the above-mentioned dispersion composition, a conductive material dispersion containing a carbon-based conductive material (C) and a medium (D), a coating film using the same, a secondary battery and the like will be described in detail.
• the present invention is not limited to the following embodiments, and the present invention also includes embodiments implemented without changing the gist.
• composition containing the polymer (A) and the component (B) of the present invention may be referred to as a "dispersant composition” or simply a “dispersant”.
• coating film of the present invention may be referred to as an "electrode film”.
• the polymer (A) contains one or more selected from the group consisting of a nitrile group-containing structural unit, a carboxyl group-containing structural unit, a hydroxyl group-containing structural unit, and a heterocycle-containing structural unit.
• the weight average molecular weight of the polymer (A) is 5,000 or more and 360,000 or less.
• the polymer (A) preferably contains an alkylene structure in the main chain. Having a structure of any one selected from the group consisting of a nitrile group, a carboxyl group, a hydroxyl group, and a heterocycle in the molecule has strong polarizability.
• the polymer (A) contains two or more selected from the group consisting of a nitrile group-containing structural unit, a carboxyl group-containing structural unit, a hydroxyl group-containing structural unit, and a heterocycle-containing structural unit. Is preferable.
• the polymer (A) contains two or more kinds of structural units, the adsorptivity to the carbon-based conductive material and the affinity to the medium are enhanced, which is more preferable.
• the weight average molecular weight of the polymer (A) is a polystyrene-equivalent weight average molecular weight, preferably 5,000 or more, more preferably 6,000 or more, and even more preferably 8,000 or more. Further, 360,000 or less is preferable, 260,000 or less is more preferable, and 100,000 or less is further preferable.
• the polymer has an appropriate weight average molecular weight, the adsorptivity to the object to be dispersed is improved, and the stability of the dispersion is further improved.
• the nitrile group-containing structural unit is a structural unit containing a nitrile group, and preferably includes a structural unit containing an alkylene structure substituted with a substituent containing a nitrile group.
• the alkylene structure is preferably a linear or branched alkylene structure.
• the number of nitrile groups contained in the nitrile group-containing structural unit is preferably one or two, and more preferably one.
• the method for introducing the nitrile group-containing structural unit into the polymer (A) is not particularly limited. As one embodiment, for example, a method of preparing a polymer by a polymerization reaction of a monomer containing a nitrile group can be preferably used.
• the monomer containing a nitrile group examples include acrylonitrile, metaacrylonitrile, and fumaronitrile. One of these can be used alone or in combination of two or more.
• the monomer containing a nitrile group is acrylonitrile, the bending of the copolymer is reduced, and the adjacent cyano groups are oriented to form a partially structured structure with strong polarization. Therefore, the intramolecular force between the polymers or between the polymer and the carbon-based conductive material becomes high.
• the monomer containing a nitrile group is preferably acrylonitrile from the viewpoint of enhancing the intermolecular force, the availability of raw materials, and the reactivity.
• the content of the nitrile group-containing structural unit shall be 30% by mass or more when the mass of the polymer (excluding the initiator and the chain transfer agent) is 100% by mass from the viewpoint of increasing the intermolecular force. Is more preferable, 45% by mass or more is more preferable, and 60% by mass or more is further preferable. On the other hand, the content is preferably 100% by mass or less, more preferably 93% by mass or less, and further preferably 87% by mass or less.
• the carboxyl group-containing structural unit is a structural unit containing a carboxyl group, and preferably includes a structural unit containing an alkylene structure substituted with a substituent containing a carboxyl group.
• the alkylene structure is preferably a linear or branched alkylene structure.
• the number of carboxyl groups contained in the carboxyl group-containing structural unit is preferably one or two, and more preferably one.
• the method for introducing the carboxyl group-containing structural unit into the polymer (A) is not particularly limited.
• a method of preparing a polymer by a polymerization reaction of a monomer containing a carboxyl group or a method of preparing a polymer by a polymerization reaction of a monomer containing a functional group other than a carboxyl group and modifying it into a carboxyl group can be mentioned.
• a method of preparing a polymer by a polymerization reaction of a monomer containing a carboxyl group can be preferably used.
• Examples of the monomer containing a carboxyl group include unsaturated fatty acids such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid, 2- (meth) acryloyloxyethyl phthalate, and 2- (meth). ) Acryloyloxypropylphthalate, 2- (meth) acryloyloxyethyl hexahydrophthalate, 2- (meth) acryloyloxypropylhexahydrophthalate, ethylene oxide-modified succinic acid (meth) acrylate, ⁇ -carboxyethyl (meth) acrylate, etc.
• unsaturated fatty acids such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid
• 2- (meth) acryloyloxyethyl phthalate 2- (meth).
• Examples thereof include carboxyl group-containing (meth) acrylate.
• Examples thereof include acid anhydride group-containing monomers such as maleic anhydride, itaconic anhydride and citraconic anhydride, which are multimers of the above carboxyl group-containing monomers, and monofunctional alcohol adducts thereof.
• a carboxyl group-containing monomer may be obtained by hydrolyzing the carbamoyl group of the polymer obtained by the polymerization reaction of the carbamoyl group-containing monomer such as (meth) acrylamide.
• carbamoyl group-containing monomer unsaturated fatty acids are preferable, (meth) acrylic acid is more preferable, and acrylic acid is even more preferable.
• the content of the carboxyl group-containing structural unit is when the mass of the polymer (excluding the initiator and the chain transfer agent) is 100% by mass from the viewpoint of having an appropriate affinity with the medium (D) described later. , 40% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more. On the other hand, the content may be preferably 98% by mass or less. In one embodiment, the content may be 100% by weight. In one embodiment, when the monomer (A) further contains one or more selected from the group consisting of a nitrile group-containing structural unit, a hydroxyl group-containing structural unit, and a heterocyclic-containing structural unit, carbon-based conductivity. The affinity between the material and the medium is high, which is more preferable.
• the content of the carboxyl group-containing structural unit is the total mass of the polymer ( However, when the amount (excluding the initiator and the chain transfer agent) is 100% by mass, it is preferably 3% by mass or more, more preferably 9% by mass or more, and further preferably 14% by mass or more. preferable. Further, from the viewpoint of electrolytic solution resistance and prevention of moisture absorption during storage, it is preferably 47% by mass or less based on the mass of the polymer (that is, when the mass of the polymer is 100% by mass). It is more preferably 37% by mass or less, and further preferably 27% by mass or less.
• the hydroxyl group-containing structural unit is a structural unit containing a hydroxyl group, and preferably includes a structural unit containing an alkylene structure substituted with a substituent containing a hydroxyl group.
• the alkylene structure is preferably a linear or branched alkylene structure.
• the number of hydroxyl groups contained in the hydroxyl group-containing structural unit is preferably one or two, and more preferably one.
• the method for introducing the hydroxyl group-containing structural unit into the polymer (A) is not particularly limited.
• a method of preparing a polymer by a polymerization reaction of a monomer containing a hydroxyl group or a method of preparing a polymer by a polymerization reaction of a monomer containing a functional group other than a hydroxyl group and modifying it into a hydroxyl group can be mentioned.
• a rational method can be selected from the viewpoint of reactivity and raw material price.
• Examples of the monomer containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, and 4-hydroxyvinylbenzene. Examples thereof include 2-hydroxy-3-phenoxypropyl acrylate or a caprolactone adduct of these monomers (the number of moles added is 1 to 5).
• the monomer containing a hydroxyl group is preferably hydroxyalkyl (meth) acrylate, more preferably 2-hydroxyethyl (meth) acrylate, and even more preferably 2-hydroxyethyl acrylate.
• the acetyl group of polyvinyl acetate obtained by polymerizing vinyl acetate is converted into sodium hydroxide.
• examples thereof include a method of saponifying with an alkali such as the above to make a hydroxyl group (saponification reaction).
• At least a part of the hydroxyl groups in the polymer may be reacted with an aldehyde compound to be modified into an acetal group before use (acetalization).
• the aldehyde compound used in the acetalization reaction can be, for example, a linear, branched, cyclically saturated, unsaturated, or aromatic aldehyde compound having 1 to 15 carbon atoms, but is not limited thereto. ..
• aldehyde examples thereof include formaldehyde, acetaldehyde, propionylaldehyde, n-butyraldehyde, isobutyraldehyde, tert-butyraldehyde, benzaldehyde, cyclohexylaldehyde and the like.
• aldehyde compounds may be used alone or in combination of two or more. Further, these aldehyde compounds may be those in which one or more hydrogen atoms are substituted with halogen or the like, except for formaldehyde.
• the content of the hydroxyl group-containing structural unit is preferably 80% by mass or more, preferably 85% by mass or more, when the mass of the polymer (excluding the initiator and the chain transfer agent) is 100% by mass. It is more preferable to have it, and it is preferable that it is 99.8% by mass or less. However, when one or more selected from the group consisting of a nitrile group-containing structural unit, a hydroxyl group-containing structural unit, and a heterocycle-containing structural unit is further contained, the content may be 5% by mass or more. It is preferably 95% by mass or less, and more preferably 85% by mass or less.
• the polarization can be strengthened and the affinity for the carbon-based conductive material and the medium can be enhanced. It is also preferable from the viewpoint of resistance to the electrolytic solution. Further containing one or more selected from the group consisting of a nitrile group-containing structural unit, a hydroxyl group-containing structural unit, and a heterocycle-containing structural unit is particularly preferable because the polarization becomes stronger.
• the content of the acetal group is preferably within a preferable range of the content of the hydroxyl group-containing structural unit for the same reason as the content of the hydroxyl group-containing structural unit.
• the heterocyclic-containing structural unit is a structural unit containing a heterocycle, and a structural unit containing an alkylene structure substituted with a substituent containing a heterocycle is more preferable.
• the alkylene structure is preferably a linear or branched alkylene structure.
• the heterocycle contained in the heterocyclic-containing structural unit may have a monocyclic structure or a condensed ring structure, but is preferably a monocyclic structure. Further, the number of heterocycles contained in the heterocyclic-containing structural unit is preferably one or two, and more preferably one. Heterocycles contain atoms other than carbon in the atoms that make up the ring.
• the heterocycle contains one or more nitrogen atoms, oxygen atoms, sulfur atoms and the like.
• a nitrogen atom or an oxygen atom is preferable, and a nitrogen atom is more preferable.
• the method for introducing the heterocycle into the polymer (A) is not particularly limited. For example, a method of preparing a polymer by a polymerization reaction of a monomer containing a heterocycle can be used.
• the monomer containing a heterocycle is preferably an N-vinyl cyclic amide structural unit, for example, N-vinyl-2-pyrrolidone, N-vinyl- ⁇ -caprolactam, N-vinyl-2-piperidone, N-vinyl-3-.
• N-vinyl-2-pyrrolidone is preferable from the viewpoint of improving battery characteristics. These can be used alone or in combination of two or more.
• the content of the heterocycle-containing structural unit is such that when the mass of the polymer (excluding the initiator and the chain transfer agent) is 100% by mass, the polarization is strengthened as described above to the carbon-based conductive material. From the viewpoint of enhancing the action, it is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more. In one embodiment, the content may be 100% by weight. However, when one or more selected from the group consisting of a nitrile group-containing structural unit, a carboxyl group-containing structural unit, and a hydroxyl group-containing structural unit is further contained, the content of the heterocycle-containing structural unit is the polymer.
• the mass of the polymer is 100% by mass
• it is preferably 5% by mass or more, and more preferably 10% by mass or more.
• the content is preferably 95% by mass or less, more preferably 85% by mass or less.
• the polymer (A) is further selected as another structural unit from the group consisting of an active hydrogen group-containing structural unit (excluding carboxyl group and hydroxyl group), a basic group-containing structural unit, and an ester group-containing structural unit. It may contain one or more structural units.
• the structural unit is selected and contained according to the characteristics such as hydrophilicity, hydrophobicity, acidity, and basicity of the base material to which the conductive material dispersion according to the embodiment of the present invention is applied, or the material to be mixed. Therefore, it can be easily applied to various uses.
• the content of other structural units is 20% by mass from the viewpoint of not impairing the polarization of the polymer (A) when the mass of the polymer (excluding the initiator and the chain transfer agent) is 100% by mass. It is preferably less than or equal to, more preferably 10% by mass or less, still more preferably 5% by mass or less.
• the active hydrogen group-containing structural unit is a structural unit having, for example, a primary amino group, a secondary amino group, a mercapto group, or the like as an active hydrogen group.
• the "primary amino group” means -NH 2 (amino group)
• the "secondary amino group” means that one hydrogen atom on the primary amino group is replaced with an organic residue such as an alkyl group. Means the group that was made.
• the primary amino group and the secondary amino group in the acid amide are not included in the active hydrogen group in the present specification.
• the basic group-containing structural unit is a structural unit having a basic group.
• Examples of the basic group include a tertiary amino group and an amide group.
• the structural unit having a primary amino group and the structural unit having a secondary amino group are also included in the basic group-containing structural unit. However, in the present invention, it is treated as the active hydrogen group-containing structural unit and is not included in the basic group-containing structural unit.
• R 1 is a hydrogen atom or a methyl group, and at least one of them is a hydrogen atom.
• R 2 is an alkyl group which may have a substituent. Those containing the active hydrogen group or the basic group as the substituent of the alkyl group are treated as the active hydrogen group-containing structural unit or the basic group-containing structural unit and are not included in the ester group-containing structural unit.
• the combination of the structural units contained in the polymer (A) is a nitrile group-containing structural unit / carboxyl group-containing structural unit, a nitrile group-containing structural unit / a carboxyl group-containing structural unit / a hydroxyl group-containing structural unit, and a nitrile.
• Group-containing structural unit / hetero-ring-containing structural unit, hydroxyl group-containing structural unit / hetero-ring-containing structural unit, hydroxyl group-containing structural unit / acetyl group-containing structural unit, and hydroxyl group-containing structural unit / acetyl group-containing structural unit / acetal group It is preferably one selected from the group consisting of the contained structural units.
• the polymer (A) preferably contains a combination of a nitrile group-containing structural unit / a carboxyl group-containing structural unit.
• the method for producing the polymer (A) is not particularly limited.
• a solution polymerization method, a suspension polymerization method, a bulk polymerization method, an emulsion polymerization method, a precipitation polymerization method and the like can be mentioned.
• a solution polymerization method or a precipitation polymerization method is preferable.
• the polymerization reaction system include addition polymerization such as ionic polymerization, free radical polymerization, and living radical polymerization. Of these, free radical polymerization or living radical polymerization is preferable.
• examples of the radical polymerization initiator include peroxides, azo-based initiators and the like.
• Examples of the polymerization initiator include, but are not limited to, the following when performing radical polymerization. Di-t-butyl peroxide, lauroyl peroxide, stearyl peroxide, benzoyl peroxide, t-butylperoxyneodecanate, t-butylperoxypivalate, dilauroyl peroxide, dicumyl peroxide, t-butyl Organic peroxidation of peroxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, etc.
• polymerization initiators are generally used in an amount of 1% by mass or less based on the total mass of all the monomers used (that is, when the total mass of all the monomers is 100% by mass). ..
• the blending amount of the polymerization initiator can be appropriately selected in consideration of the temperature at which the polymerization is carried out and the half-life of the polymerization initiator.
• the molecular weight of the polymer to be produced can be controlled by using a chain transfer agent or the like within a range that does not impair the object of the present invention.
• Chain transfer agents include, for example, alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, 3-mercapto-1,2-propanediol, octyl thioglycolate, nonyl thioglycolate, thioglycolic acid-2.
• Examples thereof include thioglycolic acid esters such as ethylhexyl, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, ⁇ -pinene, ⁇ -pinene and the like. From the viewpoint of handleability and stability, in particular, 3-mercapto-1,2-propanediol, thioglycolic acid esters, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene. -1-Cyclohexene, ⁇ -pinene, ⁇ -pinene and the like are preferable.
• the obtained polymer has a low odor.
• the chain transfer agent can be appropriately added depending on the required molecular weight. Generally, it is preferably used in the range of 0.001% by mass to 4% by mass based on the total mass of all the monomers used (that is, when the total mass of all the monomers is 100% by mass). In one embodiment, the blending amount of the chain transfer agent is preferably 0.01 to 4% by mass, more preferably 0.1 to 2% by mass.
• molecular weight control methods a method of changing the polymerization method, a method of adjusting the amount of the polymerization initiator, a method of changing the polymerization temperature, and the like can be mentioned.
• these molecular weight control methods only one kind of method may be used alone, or two or more kinds of methods may be used in combination.
• the polymer (A) can function as a dispersant.
• the content of the polymer (A) in the conductive material dispersion is preferably determined according to the specific surface area of the conductive material and the wettability.
• the content of the polymer (A) is preferably 2% by mass or more, preferably 20% by mass, based on the mass of the conductive material (that is, when the mass of the conductive material is 100% by mass). It is more preferably mass% or more, and further preferably 30 mass% or more.
• the content is preferably 250% by mass or less, more preferably 150% by mass or less, and further preferably 100% by mass or less.
• the polymer (E) is a polymer component having a molecular weight of less than 1,000 contained in the polymer (A). From the viewpoint of suppressing foaming and facilitating defoaming and defoaming, the content of the polymer (E) is based on the total mass of the polymer (A) (that is, the mass of the polymer (A)). (In the case of 100% by mass), it is preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less.
• the polymer (E) in the polymer (A) When the content of the polymer (E) in the polymer (A) is adjusted within the above range, the polymer (E) elutes into the electrolytic solution, increases the viscosity of the electrolytic solution, and increases the dielectric constant of the electrolytic solution solvent. Problems that reduce it can be easily suppressed.
• the content of the polymer (E) can be measured by general gel permeation chromatography (GPC). More specifically, for example, the measurement can be performed according to the method described in Examples.
• GPC general gel permeation chromatography
• a method for adjusting the content of the polymer (E) to 5% by mass or less based on the total mass of the polymer (A) in the polymer (A) a method for optimizing the conditions at the time of production and a weight are used.
• There is a method of purifying the coalescence For example, (1) a method of optimizing the polymerization temperature and the polymerization time to improve the polymerization reaction rate of the monomer, (2) optimizing the amount of the initiator and the chain transfer agent, and the amount of by-produced low molecular weight components.
• a precipitation polymerization method or the like in which production and purification can be performed at the same time can be mentioned. Although it depends on the composition of the polymer, the reprecipitation method or the precipitation polymerization method is preferable from the viewpoint that the amount of the polymer (E) can be easily controlled. Further, from the viewpoint of simplicity, the precipitation polymerization method is most preferable.
• a polymer having a molecular weight such as the polymer (E) may be produced in addition to the polymer having the desired molecular weight. Since it is difficult to completely separate only the polymer (E) from the polymer component, the polymer (A) may contain the polymer (E). In addition, the product obtained during the synthesis of the polymer (A) may contain a component other than the polymer component derived from the raw material, which will be described later as the component (B). Therefore, in one embodiment of the present invention, the unpurified product obtained in the synthesis step of the polymer (A) can be used as a dispersant.
• the product obtained in the synthesis step of the polymer (A) contains the target polymer (A) and the component (B) described later.
• the polymer (A) may contain the polymer (E) in a predetermined range.
• the above-mentioned dispersant (hereinafter, may be referred to as a dispersant composition) may contain a component other than the component (B), if necessary. However, it is preferable that it does not contain an emulsifier and / or a surfactant. Emulsifiers and surfactants are likely to elute into the electrolytic solution, and there is a concern that the electrolytic solution resistance may be deteriorated.
• the component (B) is a component other than the polymer derived from the raw material of the polymer (A).
• the component (B) may contain one or more selected from the group of unreacted raw materials, the above-mentioned polymerization reaction or the above-mentioned by-products produced by the modification reaction.
• the unreacted raw material include a monomer containing a nitrile group, a monomer containing a carboxyl group, a monomer capable of generating a carboxyl group by modification (for example, acrylamide, etc.), and a monomer containing a hydroxyl group, which are exemplified in the polymer (A).
• Examples thereof include a monomer capable of generating a hydroxyl group by modification (for example, vinyl acetate), an aldehyde, a monomer containing a heterocycle, a polymerization initiator, a chain transfer agent and the like.
• By-products generated in the polymerization reaction or modification reaction include metal salts such as sodium salt, potassium salt and lithium salt of the unreacted raw materials, organic salts such as ammonium salt and amine salt, acetic acid, sodium acetate and polymerization initiator.
• Examples thereof include a compound produced by deactivating without polymerizing, and a compound produced by deactivating the chain transfer agent without polymerizing.
• each of the component (B) has a highly polar structure with strong ions or polarization, it can cause foaming in a medium containing water. Further, when the component (B) remains on the electrode film, it may be eluted in the electrolytic solution to reduce the conductivity of the electrolytic solution.
• the content of the component (B) is based on the mass of the dispersant composition (that is, when the mass of the dispersant composition is 100% by mass) from the viewpoint of suppressing foaming and adverse effects on the electrolytic solution. It is preferably 2% by mass or less. In one embodiment, the content of the component (B) may be more preferably 1.9% by mass or less, still more preferably 1.8% by mass or less.
• the content of the component (B) is preferably 1.5% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less. .. In one embodiment, the content of the component (B) is preferably 0.001% by mass or more, more preferably 0.005% by mass or more. Among them, for the same reason, the content of the polymerization initiator and the compound produced by deactivating the polymerization initiator without polymerization is based on the mass of the dispersant composition (that is, the mass of the dispersant composition). Is 100% by mass), more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less.
• the content of the chain transfer agent and the compound produced by deactivating the chain transfer agent without polymerizing is based on the mass of the dispersant composition (that is, the mass of the dispersant composition). (In the case of 100% by mass), it is preferably 1% by mass or less, and more preferably 0.5% by mass or less.
• the content of the component (B) can be determined from the sum of the amount of the volatile component of the dispersant composition and the amount of the salt component by ion chromatography. More specifically, the structure and content can be determined by gas chromatographic analysis of the dispersant composition.
• the structure and content of the component (B) by gas chromatography are calculated by, for example, the following measurement conditions, but can be appropriately adjusted depending on the raw material of the polymer and the type of compound expected from the structure.
• Analyzer Gas Chromatography (GC-2025, manufactured by Shimadzu Corporation) Solvent: DMF
• Carrier gas helium (35 kPa)
• Injection port temperature 110 ° C
• a method for reducing the content of the component (B) there are a method for optimizing the conditions at the time of production and a method for purifying the polymer.
• a method for optimizing the conditions at the time of production for example, when the polymer (A) is produced by radical polymerization in a solution, the polymerization temperature and the polymerization time are optimized to improve the polymerization reaction rate of the monomer. Examples thereof include a method of optimizing the selected initiator and a method of suppressing the formation of a low-molecular-weight component (B) such as an initiator residue.
• Examples of the method for purifying the polymer include a method of removing the low molecular weight component (B) at the production stage and a method of removing the low molecular weight component (B) after the production.
• a method for removing the low molecular weight component (B) at the production stage a precipitation polymerization method capable of obtaining the target polymer (A) by filtration and removing the low molecular weight component (B) by filtration washing is used. Can be mentioned.
• a method of adding a large amount of water or a solvent to the polymer (A) solution produced by emulsion polymerization or solution polymerization and adjusting the concentration while removing the low molecular weight component (B) by distillation can be mentioned.
• the polymer (A) solution produced in the solution is dropped into a poor solvent to precipitate, and the low molecular weight component (B) is removed by filtration washing.
• Examples thereof include a method of removing the component (B) that could not be completely removed by the reprecipitation method, and a method of removing the component (B) by vacuum drying.
• the reprecipitation method and the precipitation polymerization method are preferable from the viewpoint of easy control of the amount of the component (B), and the precipitation polymerization method is most preferable from the viewpoint of convenience.
• the carbon-based conductive material (C) contains at least a carbon-based conductive material, and may contain other conductive materials, if necessary.
• the carbon-based conductive material include carbon materials such as carbon black, carbon nanotubes, carbon fibers, and graphite.
• carbon black or carbon nanotubes are preferable from the viewpoint of conductivity and density.
• carbon nanotubes have an extremely strong cohesive force and a high aspect ratio, so that they have the effect of breaking through the foam film and breaking the bubbles. preferable.
• One type of carbon-based conductive material may be used, or two or more types may be used in combination.
• two or more carbon-based conductive materials of the same type having different physical properties may be used in combination.
• Examples of the same type of carbon-based conductive material having different physical properties include two types of carbon nanotubes having different average outer diameters or average fiber diameters, two types of carbon black having different specific surface areas, and the like.
• the specific surface area of the carbon-based conductive material calculated by the BET method is preferably 100 m 2 / g or more, and more preferably 150 m 2 / g or more. On the other hand, the specific surface area is preferably 1200 m 2 / g or less, and more preferably 850 m 2 / g or less.
• the carbon nanotubes may have a shape in which flat graphite is wound in a cylindrical shape, and may include single-walled carbon nanotubes and multi-walled carbon nanotubes, which may be mixed. Further, carbon nanotubes having different diameters may be mixed. Single-walled carbon nanotubes have a structure in which one layer of graphite is wound. Multi-walled carbon nanotubes have a structure in which two or three or more layers of graphite are wound. Further, the side wall of the carbon nanotube does not have to have a graphite structure. Further, for example, a carbon nanotube having a side wall having an amorphous structure is also a carbon nanotube in the present specification.
• the shape of carbon nanotubes is not limited. Such shapes include various shapes including needle shape, cylindrical tube shape, fish bone shape (fishbone or cup laminated type), playing card shape (platelet) and coil shape.
• the shape of the carbon nanotubes is preferably needle-shaped or cylindrical tube-shaped.
• the carbon nanotubes may have a single shape or a combination of two or more shapes.
• Examples of the form of carbon nanotubes include graphite whisker, carbonentas carbon, graphite fiber, ultrafine carbon tube, carbon tube, carbon fibril, carbon microtube and carbon nanofiber.
• the carbon nanotubes may have a single form thereof or a combination of two or more kinds thereof.
• the average outer diameter of the carbon nanotubes is preferably 1 nm or more. Further, it is preferably 30 nm or less, more preferably 20 nm or less, further preferably 10 nm or less, and particularly preferably 7 nm or less.
• the average outer diameter can be calculated as follows. First, the carbon nanotubes are observed and imaged with a transmission electron microscope. Next, in the observation photograph, any 300 carbon nanotubes are selected and the outer diameter of each is measured. Next, the average outer diameter (nm) of the carbon nanotubes is calculated as the number average of the outer diameters.
• the value obtained by dividing the average fiber length of carbon nanotubes by the average outer diameter is called the aspect ratio.
• the aspect ratio of the carbon nanotubes is preferably 20 or more, more preferably 50 or more, preferably 5000 or less, and more preferably 200 or less.
• the average fiber length used to calculate the aspect ratio can be calculated as follows. First, carbon nanotubes are observed and imaged with a scanning electron microscope. Next, in the observation photograph, any 300 carbon nanotubes are selected and the fiber length of each is measured. Next, the average fiber length of the carbon nanotubes is calculated as the number average of the fiber lengths.
• the average fiber length of the carbon nanotubes is preferably 0.3 ⁇ m or more, more preferably 0.5 ⁇ m or more, in order to form an efficient conductive network and exert the defoaming effect. It is preferably 5.0 ⁇ m or less, and more preferably 2.0 ⁇ m or less.
• carbon black examples include acetylene black, furnace black, hollow carbon black, channel black, thermal black, and Ketjen black. Further, the carbon black may be neutral, acidic or basic, and an oxidation-treated carbon black or a graphitized carbon black may be used. When carbon black is used, acetylene black having a high aspect ratio and a high defoaming effect is more preferable.
• conductive materials include, for example, gold, silver, copper, silver-plated copper powder, silver-copper composite powder, silver-copper alloy, amorphous copper, nickel, chromium, palladium, rhodium, ruthenium, indium, silicon, aluminum, tungsten. , Morbutene, metal powders such as platinum, inorganic powders coated with these metals, powders of metal oxides such as silver oxide, indium oxide, tin oxide, zinc oxide, ruthenium oxide, inorganic substances coated with these metal oxides.
• the powder and other conductive materials may be used alone or in combination of two or more.
• the content of the carbon-based conductive material is preferably 0.1 to 25% by mass based on the non-volatile content of the conductive material dispersion (that is, when the mass of the non-volatile content of the conductive material dispersion is 100% by mass). , 0.3-10% by mass is more preferable. Within the above range, the conductive material can be present in a good and stable manner without causing sedimentation or gelation. Further, the content of the conductive material is preferably adjusted as appropriate so that a conductive material dispersion having appropriate fluidity or viscosity can be obtained depending on the specific surface area of the conductive material, the affinity for the dispersion medium, and the like.
• the medium (D) contains at least water and may optionally contain other water-friendly media.
• the conductive material dispersion may further contain a small amount of defoaming agent.
• the amount of the defoaming agent added is preferably 5% by mass or less, more preferably 3% by mass or less, based on the mass of the conductive material dispersion (that is, when the mass of the conductive material dispersion is 100% by mass). 1% by mass or less is more preferable.
• the conductive material dispersion does not contain a defoaming agent.
• the defoaming agent can be arbitrarily used as long as it has a defoaming effect, such as a commercially available defoaming agent, a wetting agent, and a water-soluble organic solvent, and may be used alone or in combination of two or more.
• a defoaming effect such as a commercially available defoaming agent, a wetting agent, and a water-soluble organic solvent
• Alcohols ethanol, propanol, isopropanol, butanol, octyl alcohol, hexadecyl alcohol, acetylene alcohol, ethylene glycol monobutyl ether, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, acetylene glycol, polyoxyalkylene glycol, propylene glycol, other glycols etc.
• Fatty acid ester type diethylene glycol laurate, glycerin monolithinolate, alkenyl succinic acid derivative, sorbitol monolaurate, sorbitol trioleate, polyoxyethylene monolaurate, polyoxyethylene sorbitol monolaurate, natural wax, etc.
• Amide type polyoxyalkylene amide, acrylate polyamine, etc.
• Phosphoric acid ester type tributyl phosphate, sodium octyl phosphate, etc.
• Metal soap type aluminum stearate, calcium oleate, etc. Oils and fats; animal and vegetable oils, sesame oil, castor oil, etc. Mineral oil system: kerosene, paraffin, etc.
• Silicone type dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane, fluorosilicone oil, etc.
• Water-soluble organic solvent other than alcohol-based N-methyl-2-pyrrolidone and the like. Of these, alcohol-based or N-methyl-2-pyrrolidone is preferable from the viewpoint of suppressing the influence on the diffusion resistance and conductivity of the electrolytic solution. From the viewpoint of defoaming effect, acetylene glycol type is preferable. When the defoaming agent as described above is used, the surface tension of the conductive material dispersion can be reduced.
• the surface tension of the conductive material dispersion is preferably 73 mN / m or less, more preferably 70 mN / m or less, still more preferably 65 mN / m or less, from the viewpoint of energy efficiency and coatability of the disperser.
• the defoaming agent can be added at any time from the start to the end of the dispersion process including the preparation, but from the viewpoint of chargeability and dispersion efficiency, the defoaming agent is added before the dispersion to be mixed and the dispersion medium are mixed. Is preferable. Further, it may be added at one time or may be added in a plurality of times.
• the conductive material dispersion according to the embodiment of the present invention contains a polymer (A), a component (B), a carbon-based conductive material (C), and a medium (D).
• the conductive material dispersion can be suitably used for an electrode for a secondary battery.
• it is not limited to applications of secondary batteries, and is used for power storage devices other than secondary batteries, such as electrodes for electric double-layer capacitors, electrodes for non-aqueous electrolyte capacitors, IC trays for plastic and rubber products, and electronic component materials. It can also be used as an antistatic material for a molded body, an electronic component, a substitute for a transparent electrode (ITO film), an electromagnetic wave shield, and the like.
• the conductive material dispersion according to the embodiment of the present invention can contain an additive such as an inorganic base, an inorganic metal salt, or an organic base. Since the strong polarization of the polymer (A) interacts with the additive, the stability of dispersion over time of the object to be dispersed is further improved.
• an additive such as an inorganic base, an inorganic metal salt, or an organic base. Since the strong polarization of the polymer (A) interacts with the additive, the stability of dispersion over time of the object to be dispersed is further improved.
• the inorganic base and the inorganic metal salt a compound having at least one of an alkali metal and an alkaline earth metal is preferable.
• Inorganic bases and inorganic metal salts include chlorides, hydroxides, carbonates, nitrates, sulfates, phosphates, tungstates, vanadium salts, molybdenates, of alkali metals and alkaline earth metals.
• alkali metals examples include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like.
• alkali metal hydroxide examples include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like.
• hydroxide of the alkaline earth metal examples include calcium hydroxide and magnesium hydroxide.
• alkali metal carbonate examples include lithium carbonate, lithium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and the like.
• carbonates of alkaline earth metals examples include calcium carbonate and magnesium carbonate.
• the alkali metal alkoxides include, for example, lithium methoxyd, lithium ethoxydo, lithium-n-butoxide, lithium-t-butoxide, potassium methoxyd, potassium ethoxydo, potassium-n-butoxide, potassium-t-butoxide, sodium methoxy. Do, sodium ethoxydo, sodium-n-butoxide, sodium-t-butoxide and the like can be mentioned.
• the alkoxide may have 5 or more carbon atoms.
• Examples of the alkali earth metal alkoxide include magnesium methoxydo, magnesium ethoxydo, magnesium-n-butoxide, magnesium-t-butoxide and the like.
• the alkoxide may have 5 or more carbon atoms.
• lithium hydroxide, sodium hydroxide, lithium carbonate, sodium carbonate, lithium-t-butoxide, potassium-t-butoxide, and sodium-t-butoxide are more preferable.
• the metal contained in the inorganic base and the inorganic metal salt of the present invention may be a transition metal.
• organic base examples include primary, secondary and tertiary alkylamines having 1 to 40 carbon atoms and having an optionally substituted alkyl group, or compounds containing a basic nitrogen atom thereof.
• Primary alkylamines having 1 to 40 carbon atoms and having an alkyl group which may be substituted include, for example, propylamine, butylamine, isobutylamine, octylamine, 2-ethylhexylamine, laurylamine, stearylamine, oleylamine, and the like. Examples thereof include 2-aminoethanol, 3-aminopropanol, 3-ethoxypropylamine and 3-lauryloxypropylamine.
• Secondary alkylamines having 1-40 carbon atoms and optionally substituted alkyl groups include, for example, dibutylamine, diisobutylamine, N-methylhexylamine, dioctylamine, distearylamine, 2-methylaminoethanol. And so on.
• the tertiary alkylamine having 1 to 40 carbon atoms and having an alkyl group which may be substituted is, for example, triethylamine, tributylamine, N, N-dimethylbutylamine, N, N-diisopropylethylamine, dimethyloctylamine, tri. -N-butylamine, dimethylbenzylamine, trioctylamine, dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylpalmitylamine, dimethylstearylamine, dilaurylmonomethylamine, triethanolamine, 2- (dimethylamino) ethanol And so on.
• primary, secondary or tertiary alkylamines having 1 to 30 carbon atoms and having an optionally substituted alkyl group are preferable, and they have 1 to 20 carbon atoms and are substituted.
• Primary, secondary or tertiary alkylamines with good alkyl groups are more preferred.
• the substituted alkyl group means that the hydrogen atom may be substituted, and examples of the substituent include a hydroxy group and the like.
• DBU 1,8-diazabicyclo [5.4.0] undecene-7
• DBN 1,5-diazabicyclo [4.3.0] nonen-5
• DBU 1,8-diazabicyclo [5.4.0] undecene-7
• DBN 1,5-diazabicyclo [4.3.0] nonen-5
• DABCO 1,4-Diazabicyclo [2.2.2] octane
• imidazole 1-methylimidazole and the like.
• the total amount of the inorganic base, the inorganic metal salt, and the organic base is 1% by mass or more based on the mass of the dispersant composition (that is, when the mass of the dispersant composition is 100% by mass). It is preferably 100% by mass or less, and more preferably 50% by mass or less. When an appropriate amount is blended, the wettability of the carbon-based conductive material is further improved.
• the pH of the conductive material dispersion is preferably 6.0 or more and 11.0 or less, more preferably 7.0 or more and 11.0 or less, and further preferably 8.0 to 11.0. ..
• the pH can be measured with a general pH meter.
• the dispersibility of the conductive material in the conductive material dispersion can be evaluated by the complex elastic modulus and the phase angle by dynamic viscoelasticity measurement.
• the complex elastic modulus indicates the hardness of the conductive material dispersion, and tends to be smaller as the dispersibility of the conductive material is better and as the viscosity is lower.
• the complex elastic modulus may be a high value.
• the complex elastic modulus by dynamic viscoelasticity measurement of the conductive material dispersion is preferably 5 Pa or more, more preferably 10 Pa or more at 25 ° C. and 1 Hz, while the complex elastic modulus is. At 25 ° C. and 1 Hz, it is preferably 650 Pa or less, more preferably 400 Pa or less, and even more preferably 100 Pa or less. As one embodiment, the complex elastic modulus of the conductive material dispersion is preferably 5 Pa or more and 650 Pa or less at 25 ° C. and 1 Hz.
• the phase angle means the phase shift of the stress wave when the strain applied to the conductive material dispersion is a sine wave. In the case of a pure elastic body, the phase angle is 0 ° because the sine wave has the same phase as the applied strain. On the other hand, if it is a pure viscous body, the stress wave is advanced by 90 °. In a general sample for viscoelasticity measurement, if the phase angle is a sine wave larger than 0 ° and smaller than 90 ° and the dispersibility of the conductive material in the conductive material dispersion is good, the phase angle is 90. Approaching °.
• the phase angle of the conductive material dispersion measured by dynamic viscoelasticity is preferably 3 ° or more, more preferably 5 ° or more at 25 ° C. and 1 Hz. It is more preferably 10 ° or more.
• the phase angle is preferably less than 60 ° and preferably less than 50 ° at 25 ° C and 1 Hz.
• the phase angle at 25 ° C. and 1 Hz by dynamic viscoelasticity measurement of the conductive material dispersion is preferably 3 ° or more and less than 60 °.
• a developed conductive network is formed by uniformly and satisfactorily dispersing a conductive material having a large fiber length of carbon nanotubes or a large structure length of carbon black while keeping the length above a certain level. Therefore, it is not only necessary that the viscosity of the conductive material dispersion is low and the dispersibility (apparently) is good, but that either or both of the complex modulus and the phase angle are combined with a conventional index such as viscosity. It is important to judge the distributed state. Above all, it is especially important to give priority to the phase angle. From such a viewpoint, by setting the complex elastic modulus and the phase angle within the above ranges, a conductive material dispersion having good conductivity and electrode strength can be easily obtained. The complex elastic modulus and the phase angle of the conductive material dispersion can be measured by the method described in Examples.
• the viscosity of the conductive material dispersion of the present embodiment is preferably 5 Pa ⁇ s or more, and more preferably 10 Pa ⁇ s or more, when measured at a shear rate of 1 (s -1 ) using a reometer. It is more preferably 20 Pa ⁇ s or more, more preferably less than 60 Pa ⁇ s, and even more preferably less than 40 Pa ⁇ s. Further, when measured at a shear rate of 10 (s -1 ) using a leometer, it is preferably 1 Pa ⁇ s or more, and preferably less than 10 Pa.
• the cumulative particle size D10 measured by the laser diffraction method of the conductive material dispersion of the present embodiment is preferably 100 nm or more, more preferably 200 nm or more, particularly preferably 300 nm or more, and further preferably 500 nm. It is preferably less than, and more preferably less than 400 nm.
• the cumulative particle size D50 measured by the laser diffraction method of the conductive material dispersion is preferably 200 nm or more.
• the cumulative particle size D10 is preferably less than 3000 nm, more preferably less than 2000 nm, and even more preferably less than 1500 nm.
• the particle size measured by the laser diffraction method correlates with the length of the conductive material in the dispersion (fiber length of carbon nanotubes or structure length of carbon black), and the cumulative particle sizes D10 and D50 are in the above range.
• the material dispersion has a good dispersed state of the conductive material in the dispersion. Further, if it exceeds the above range, the conductive material in an aggregated state exists, and if it is below the above range, a large number of finely cut conductive materials are generated, which makes it difficult to form an efficient conductive network.
• the cumulative particle size D10 when the cumulative particle size D10 is less than the above range, the conductive material is damaged and contains a large amount of the conductive material in an excessively dispersed state, so that it becomes difficult to form a developed conductive network.
• the cumulative particle size D10 and the cumulative particle size D50 can be obtained by using a general dynamic light scattering measuring device, but more specifically, the cumulative particle size D10 and the cumulative particle size D50 can be measured by the method described in Examples. can. In the present specification, the cumulative particle size D10 and the cumulative particle size D50 may be simply referred to as “D10” and “D50”, respectively.
• the conductive material dispersion of the present invention is produced by, for example, finely dispersing a composition (raw material) containing a dispersant, a carbon-based conductive material, and a medium by performing a dispersion treatment using a dispersion device. Is preferable.
• the timing of addition of the material to be used may be arbitrarily adjusted, and the multi-step treatment may be performed two or more times.
• a disperser usually used for pigment dispersion or the like can be used.
• examples thereof include a kneader, a two-roll mill, a three-roll mill, a planetary mixer, a ball mill, a horizontal sand mill, a vertical sand mill, an annual bead mill, an attritor, a high shea mixer, a disper, or a high-pressure homogenizer.
• the pressure when using the high-pressure homogenizer is preferably 60 to 150 MPa, more preferably 60 to 120 MPa.
• Dispersion methods using a disperser include batch type distribution, path type distribution, circulation distribution, and the like, but any method may be used, and two or more methods may be combined.
• the batch type dispersion is a method of performing distribution only by the main body of the distribution device without using piping or the like. Since it is easy to handle, it is preferable for small-quantity production.
• the pass-type dispersion is a dispersion method in which the dispersion device main body is provided with a tank for supplying the dispersion-to-dispersed liquid via a pipe and a tank for receiving the dispersion-to-dispersed liquid, and the dispersion device main body is passed (passed).
• the circulation type dispersion is a method in which the liquid to be dispersed that has passed through the main body of the dispersion device is returned to the tank that supplies the liquid to be dispersed and dispersed while being circulated.
• the longer the processing time the more the dispersion progresses, so the path or circulation may be repeated until the desired dispersion state is reached, and the processing amount can be increased by changing the size of the tank and the processing time.
• the pass-type dispersion is preferable in that the dispersion state can be easily made uniform as compared with the circulation-type dispersion.
• Circulation-type dispersion is preferable in that work and manufacturing equipment are simpler than path-type dispersion.
• dispersion step crushing of aggregated particles, unraveling of conductive material, wetting, stabilization, etc. proceed sequentially or simultaneously. Since the dispersed state of the finished product differs depending on the progress, it is preferable to manage the dispersed state in each dispersion step by using various evaluation methods. For example, it can be managed by the method described in Examples described later.
• pre-dispersing is performed until the dispersion particle size becomes 200 ⁇ m or less according to the judgment by the grind gauge (according to JIS K5600-2-5), and then the main dispersion is continuously performed.
• a method for producing a conductive material dispersion is preferable.
• the present dispersion is preferably carried out using a high-pressure homogenizer or the like at a pressure of 60 to 150 MPa until the D50 becomes 100 ⁇ m or less. stomach. At this time, if the pH of the dispersion medium is adjusted to 7.0 or more and 13.5 or less by adding a base, the wettability of the conductive material can be improved and the action of the dispersant can be enhanced.
• Examples of the dispersion method for applying shear stress include a method using a dispersion device such as a three-roll mill, a planetary mixer, a high shea mixer, and a disper. Above all, it is preferable to use a high shea mixer that can disperse with a viscosity equivalent to that suitable for a high-pressure homogenizer.
• the conductive material dispersion according to the embodiment of the present invention may further contain a binder.
• the binder is not particularly limited as long as it is usually used as a binder for the secondary battery, and can be appropriately selected depending on the intended purpose. .. Further, the binder is a resin capable of bonding between substances such as a carbon-based conductive material and other particles, and is different from the polymer (A) and the polymer (E) described in the present specification.
• the binder used for the secondary battery is, for example, ethylene, propylene, vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, acrylonitrile, styrene, vinyl butyral, vinyl. Polymers or copolymers containing acetal, vinylpyrrolidone, etc.
• Polyurethane resin polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, acrylic resin, formaldehyde resin, silicon resin, fluororesin; Cellulose resin (eg, carboxymethyl cellulose (CMC)); Elastomers such as styrene-butadiene rubber, fluororubber; Examples thereof include conductive resins such as polyaniline and polyacetylene. Further, modified products and mixtures of these resins and copolymers may be used.
• a binder for a positive electrode when used as a binder for a positive electrode, a polymer or copolymer having a fluorine atom in the molecule, for example, polyvinylidene fluoride, polyvinyl fluoride, tetrafluoroethylene or the like is preferable from the viewpoint of resistance.
• a binder for the negative electrode carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, etc., which have good adhesion, are preferable.
• the content of the binder used in the secondary battery is 0.5 to 30 mass based on the mass of the non-volatile content of the conductive material dispersion (that is, the mass of the non-volatile content of the conductive material dispersion is 100% by mass). % Is preferable, and 0.5 to 25% by mass is more preferable.
• the conductive material dispersion may contain a positive electrode active material or a negative electrode active material.
• the positive electrode active material and the negative electrode active material may be simply referred to as “active material”.
• An active substance is a material that is the basis of a battery reaction.
• the active material is divided into a positive electrode active material and a negative electrode active material according to the electromotive force.
• the conductive material dispersion containing the positive electrode active material or the negative electrode active material may be referred to as a “positive electrode mixture composition”, a “negative electrode mixture composition”, or simply a “mixture composition”, respectively.
• the mixture composition is preferably in the form of a slurry in order to improve uniformity and processability.
• the mixture composition contains at least a conductive material dispersion containing an active material or a conductive material dispersion containing a binder and an active material. In the present specification, the mixture composition may be referred to as "mixture slurry”.
• the positive electrode active material is not particularly limited, but for example, for secondary battery applications, metal compounds such as metal oxides and metal sulfides capable of reversibly doping or intercalating lithium ions can be used.
• metal compounds such as metal oxides and metal sulfides capable of reversibly doping or intercalating lithium ions can be used.
• lithium manganese composite oxide eg Li x Mn 2 O 4 or Li x MnO 2
• lithium nickel composite oxide eg Li x NiO 2
• lithium cobalt composite oxide Li x CoO 2
• Composite oxides eg Li x Ni 1-y Coy O 2
• lithium manganese cobalt composite oxides eg Li x Mn y Co 1-y O 2
• lithium nickel manganese cobalt composite oxides eg Li x Ni y) Coz Mn 1-y-z O 2
• spinel-type lithium manganese nickel composite oxide for example, Li x Mn 2-y Ni y O 4
• other composite oxide powder of lithium and transition metal having an olivine structure.
• Lithium phosphorus oxide powder (eg Li x FePO 4 , Li x Fe 1-y Mn y PO 4 , Li x CoPO 4 , etc.), manganese oxide, iron oxide, copper oxide, nickel oxide, vanadium oxide (eg V 2 O) 5 , V 6 O 13 ), transition metal oxide powders such as titanium oxide, transition metal sulfide powders such as iron sulfate (Fe 2 (SO 4 ) 3 ), TiS 2 and FeS.
• x, y, and z are numbers, and 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 0 ⁇ y + z ⁇ 1.
• These positive electrode active materials may be used alone or in combination of two or more.
• lithium phosphorylated powder having an olivine structure is particularly preferable from the viewpoint of water resistance.
• the negative electrode active material is not particularly limited, but is, for example, a metal Li capable of reversibly doping or intercalating lithium ions, or an alloy thereof, a tin alloy, a silicon alloy negative electrode, Li X TIO 2 , Li X Fe 2 O 3 , Li X Fe 3 O 4 , Li X WO 2 , etc., metal oxides, polyacetylene, poly-p-phenylene, etc., conductive polymers, highly graphitized carbon materials, etc., artificial graphite, or natural graphite, etc. Powder and resin calcined carbon materials can be used. However, x is a number, and 0 ⁇ x ⁇ 1. These negative electrode active materials may be used alone or in combination of two or more.
• the content of the carbon-based conductive material in the mixture composition is preferably 0.01% by mass or more based on the mass of the active material (that is, the mass of the active material is 100% by mass), and 0. It is more preferably 02% by mass or more, and further preferably 0.03% by mass or more. Further, it is preferably 10% by mass or less, more preferably 7% by mass or less, and further preferably 5% by mass or less.
• the content of the polymer (A) in the mixture composition is preferably 0.01% by mass or more based on the mass of the active material (that is, the mass of the active material is 100% by mass), and is 0. More preferably, it is 0.02% by mass or more. Further, it is preferably 10% by mass or less, and more preferably 5% by mass or less.
• the content of the binder in the mixture composition is based on the mass of the active material (that is, the mass of the active material is 100% by mass). It is preferably 5% by mass or more, and more preferably 0.5% by mass or more. Further, it is preferably 30% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less.
• the solid content in the mixture composition is preferably 30% by mass or more, preferably 40% by mass or more, based on the mass of the mixture composition (that is, the mass of the mixture composition is 100% by mass). It is more preferable to have. Further, it is preferably 90% by mass or less, and more preferably 80% by mass or less.
• the mixture composition can be produced by various conventionally known methods. For example, a method of mixing and dispersing a dispersant, a carbon-based conductive material, a medium, a binder, and an active material; after dispersing the dispersant, the carbon-based conductive material, and the medium. Method of adding a binder after adding an active material; prepared by adding a binder after dispersing a dispersant, a carbon-based conductive material, and a medium. How to do it, etc. As a method for producing a mixed material composition, a dispersant, a carbon-based conductive material, a medium, and a component are dispersed, a binder is added, and then an active material is further added and dispersed. The method is preferred.
• the distribution device used for distribution is not particularly limited.
• a mixture composition can be obtained by using the dispersion means mentioned in the description of the conductive material dispersion. Therefore, as a method for producing the composite material composition, a treatment may be performed in which an active material is added and dispersed without adding a binder to the conductive material dispersion.
• Electrode film When a coating film formed by using a conductive material dispersion according to an embodiment of the present invention is used for a secondary battery, the coating film may be referred to as an "electrode film" in the present specification. Therefore, one embodiment of the present invention relates to an electrode membrane made of the conductive material dispersion of the above embodiment.
• the electrode membrane may further include a current collector.
• the electrode film can be obtained, for example, by applying a conductive material dispersion on the current collector and drying it, and includes the current collector and the membrane.
• An electrode film formed by using the positive electrode mixture composition can be used as the positive electrode.
• An electrode film formed by using the negative electrode mixture composition can be used as the negative electrode.
• a film formed by using a conductive material dispersion containing an active material may be referred to as an “electrode mixture layer”.
• the material and shape of the current collector used to form the electrode film are not particularly limited, and those suitable for various secondary batteries can be appropriately selected.
• Examples of the material of the current collector include conductive metals or alloys such as aluminum, copper, nickel, titanium, or stainless steel.
• As the shape a flat foil is generally used, but a current collector having a roughened surface, a perforated foil-shaped current collector, and a mesh-shaped current collector can also be used.
• the thickness of the current collector is preferably about 0.5 to 30 ⁇ m.
• the method of applying the conductive material dispersion on the current collector is not particularly limited, and a known method can be used. Specific examples thereof include a die coating method, a dip coating method, a roll coating method, a doctor coating method, a knife coating method, a spray coating method, a gravure coating method, a screen printing method, an electrostatic coating method and the like.
• Examples of the drying method include leaving drying or drying using a blower dryer, a warm air dryer, an infrared heater, a far infrared heater, or the like, but the drying method is not particularly limited thereto.
• the thickness of the formed film is, for example, 1 ⁇ m or more and 500 ⁇ m or less, preferably 10 ⁇ m or more and 300 ⁇ m or less.
• the coating film formed by using the conductive material dispersion is used as a base layer of the electrode mixture layer in order to improve the adhesion between the electrode mixture layer and the current collector or to improve the conductivity of the electrode film. It is also possible.
• the secondary battery according to the embodiment of the present invention includes a positive electrode, a negative electrode, and an electrolyte, and at least one selected from the group consisting of a positive electrode and a negative electrode includes the electrode film.
• electrolyte various conventionally known electrolytes in which ions can move can be used.
• the electrolyte is preferably dissolved in a non-aqueous solvent and used as an electrolytic solution.
• the non-aqueous solvent is not particularly limited, and is, for example, carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate; ⁇ -butyrolactone, ⁇ -valerolactone, and ⁇ .
• -Lactones such as octanoic lactones; tetrahydrofuran, 2-methyltetrachloride, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, and 1, Glymes such as 2-dibutoxyetane; esters such as methylformate, methylacetate, and methylpropionate; sulfoxides such as dimethylsulfoxide and sulfolanes; and nitriles such as acetonitrile.
• solvents may be used alone, or two or more kinds may be mixed and used.
• the secondary battery preferably contains a separator.
• the separator include, but are not limited to, polyethylene non-woven fabric, polypropylene non-woven fabric, polyamide non-woven fabric, and non-woven fabric obtained by subjecting them to a hydrophilic treatment.
• the structure of the secondary battery of the above embodiment is not particularly limited, but usually includes a positive electrode and a negative electrode, and a separator provided as needed, and is used for purposes such as a paper type, a cylindrical type, a button type, and a laminated type. It can have various shapes according to the situation.
• Dispersant 1 is a composition containing the polymer (A) described above, a trace amount of the component (B), and the polymer (E).
• the content of each structural unit shown in Table 1, the weight average molecular weight (Mw), the content of the component (B), and the content of the polymer (E) were as shown in Table 2.
• the inside of the reaction vessel is heated to 70 ° C., and a mixture consisting of 10 parts of methyl ethyl ketone and 0.4 part of 2,2'-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd .: V-65).
• V-65 2,2'-azobis (2,4-dimethylvaleronitrile)
• the product was filtered off by vacuum filtration, washed with 100 parts of methanol, further washed with 100 parts of ethyl acetate, and the solvent was completely removed by drying under reduced pressure to obtain a dispersant 5.
• the content of each structural unit shown in Table 1, the weight average molecular weight (Mw), the content of the component (B), and the content of the polymer (E) were as shown in Table 2. It was confirmed that a part of the cyano group was denatured into an amide group by the sodium hydroxide used in the saponification reaction.
• the product was filtered off by vacuum filtration, washed with 100 parts of methanol, further washed with 100 parts of ethyl acetate, and the solvent was completely removed by drying under reduced pressure to obtain a dispersant 6.
• the content of each structural unit shown in Table 1, the weight average molecular weight (Mw), the content of the component (B), and the content of the polymer (E) were as shown in Table 2. It was confirmed that a part of the cyano group was denatured into an amide group by the sodium hydroxide used in the saponification reaction.
• an initiator aqueous solution consisting of 2 parts of 2,2'-azobis-2-amidinopropane dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd .: V-50) and 18 parts of ion-exchanged water was added dropwise over one and a half hours. .. After completion of the dropping, the reaction was carried out for 3.5 hours, then an aqueous solution consisting of 0.1 part of V-50 and 0.9 part of ion-exchanged water was added, and 30 minutes later, V-50 and 0.1 part and ions were added. An aqueous solution consisting of 0.9 parts of exchanged water was added again.
• the other half was suspended by ultrasonic irradiation in a mixed solution of 100 parts of methanol and 100 parts of methyl ethyl ketone, filtered and dried under reduced pressure to obtain a dispersant 10.
• the content of each structural unit shown in Table 1, the weight average molecular weight (Mw), the content of the component (B), and the content of the polymer (E) were as shown in Table 2.
• the reaction was terminated by cooling to obtain a polyvinyl acetate / methanol solution.
• 80 parts of a 2 mol / L sodium hydroxide / methanol solution was added as the amount of sodium hydroxide, the temperature was raised to 70 ° C. and the reaction was carried out for 5 hours to obtain a polyvinyl alcohol / methanol mixed solution having a saponification degree of 98 mol%. ..
• 800 parts by mass of ion-exchanged water was added to dissolve polyvinyl alcohol, and 2 parts by mass of hydrochloric acid and 20 parts by mass of butyraldehyde were added dropwise with stirring.
• the temperature was raised to 80 ° C. and held for 1 hour to convert a part of the hydroxyl group into butyral, and the reaction was stopped by cooling.
• 250 parts of methyl ethyl ketone and 250 parts of methanol were charged in a four-neck separable flask, and the mixture was rotated 1,000 times with a disper, and the polymer solution obtained as described above was added dropwise over 1 hour.
• the generated white precipitate was taken out by filtration and dried under reduced pressure to obtain a dispersant 11.
• the content of each structural unit shown in Table 1, the weight average molecular weight (Mw), the content of the component (B), and the content of the polymer (E) were as shown in Table 2.
• an initiator aqueous solution consisting of 2 parts of 2,2'-azobis-2-amidinopropane dihydrochloride (Fujifilm Wako Pure Chemical Industries, Ltd .: V-50) and 18 parts of ion-exchanged water was added dropwise over one and a half hours. After completion of the dropping, the reaction was carried out for 3.5 hours, then an aqueous solution consisting of 0.1 part of V-50 and 0.9 part of ion-exchanged water was added, and 30 minutes later, V-50 and 0.1 part and ions were added. An aqueous solution consisting of 0.9 parts of exchanged water was added again.
• the weight average molecular weight (Mw) and the content of the polymer (E) of the synthesized polymer (A) are determined by either the measuring method 1 or the measuring method 2 depending on the solubility of the dispersant (or the comparative dispersant) in water.
• the solubility of the dispersant (or the comparative dispersant) in water was selected and measured by gel permeation chromatography (GPC) equipped with an RI detector.
• the molecular weight is a polyethylene glycol equivalent value. From the above measurement results, the weight average molecular weight (Mw) of the polymer (A) and the content of the polymer (E) having a molecular weight of less than 1,000 were calculated. (Measurement method 2) As the apparatus, HLC-8320GPC (manufactured by Tosoh Co., Ltd.) was used, and "TSK-GELSUPER AW-4000”, “AW-3000”, and “AW-2500” manufactured by Tosoh Co., Ltd. were connected in series as separation columns, and the oven temperature was 40.
• the measurement was carried out at a flow rate of 0.6 mL / min using an N, N-dimethylformamide solution of 30 mM triethylamine and 10 mM lithium bromide as an eluent at ° C.
• the sample was prepared in a solvent consisting of the above eluent at a concentration of 0.2% by mass, and 10 ⁇ L was injected.
• the molecular weight is a polystyrene-equivalent value. From the above measurement results, the weight average molecular weight (Mw) of the polymer (A) and the content of the polymer (E) having a molecular weight of less than 1,000 were calculated.
• the amount of the component (B) contained in the dispersant was calculated from the sum of the content of the volatile component determined below and the content of sodium acetate.
• the content of the component (B) contained in each dispersant is shown in Table 2.
• the content of volatile components was calculated by subtracting the amount of water quantified by Karl Fischer from the weight loss when heat-treated in a hot air oven. Approximately 0.5 g of the sample was collected in an aluminum dish, spread, allowed to stand in a hot air oven at 150 ° C. for 10 minutes, allowed to cool in a desiccator for 3 minutes, quickly weighed after drying, and the weight loss rate G. 1 (%) was calculated.
• Moisture content G 2 (%) is Karl Fischer Moisture Meter (desktop coulometric moisture meter CA-200 type: manufactured by Mitsubishi Chemical Analytech Co., Ltd., cathode liquid: manufactured by Mitsubishi Chemical Co., Ltd., Aquamicron (trademark) CXU, anode liquid. : A sample was treated at 150 ° C. under 250 ml / min flow of nitrogen gas using Aquamicron (trademark) AX manufactured by Mitsubishi Chemical Co., Ltd., and measured by the Karl Fischer method. The content of the volatile component was calculated as G1 - G2 ( %).
• the dispersants 5, 6, 10, 11 and the comparative dispersant 3 were sieved with a sieve having an opening of 1 mm (16 mesh) (based on JIS standard Z8801-1 to 3). 10 g of the powder passed through the above sieve was dried at 100 ° C. for 1 hour to remove volatile components. Next, the powder from which the volatile components had been removed and 50 mL of ultrapure water were placed in a 100 mL Erlenmeyer flask with a stopper, a cooling condenser was attached, and the mixture was stirred and extracted at 95 ° C. for 10 hours.
• the obtained extract was diluted 100-fold with ultrapure water, filtered, and then the resin component was removed using a solid-phase extraction column (InertSep HLB manufactured by GL Science Co., Ltd.). Then, using the obtained liquid, the amount of sodium acetate was calculated by ion chromatography (“ICS2000”, manufactured by Thermo Fisher Scientific). For quantification, a calibration curve prepared using an acetic acid aqueous solution was used.
• Example 1-1 ⁇ Preparation of conductive material dispersion> (Example 1-1)
• a total of 1 kg of ion-exchanged water, a dispersant, and an additive were added to the stainless steel container, and the mixture was stirred with a disper until uniform.
• the conductive material is added while stirring with a dispersion, a square hole high shea screen is attached to a high shear mixer (L5MA, manufactured by SILVERSON), the whole becomes uniform at a speed of 8,000 rpm, and the grind gauge is used.
• Batch dispersion was performed until the dispersion particle size was 250 ⁇ m or less. At this time, the dispersion particle size confirmed by the grind gauge was 180 ⁇ m.
• the dispersion liquid was supplied from a stainless steel container to a high-pressure homogenizer (Starburst Lab HJP-17007, manufactured by Sugino Machine Limited) via a pipe, and a pass-type dispersion treatment was performed 20 times until D50 became 100 ⁇ m or less.
• the dispersion treatment was performed using a single nozzle chamber with a nozzle diameter of 0.25 mm and a pressure of 100 MPa.
• the obtained conductive material dispersion (dispersion 1) had a low viscosity and good storage stability.
• each dispersion (dispersions 2 to 16) was obtained in the same manner as in Example 1-1. However, when the median diameter was 100 ⁇ m or more, an additional 2-pass dispersion treatment was performed, measurement was performed again, and the measurement was repeated until the median diameter became 100 ⁇ m or less.
• the conductive material dispersions (dispersions 2 to 16) according to the embodiment of the present invention all had low viscosity and good storage stability.
• the amount of defoaming agent shown in Table 4 was added, and batch-type dispersion was performed again until the whole became uniform and the dispersion particle size became 250 ⁇ m or less.
• the dispersion liquid was supplied from a stainless steel container to a high-pressure homogenizer (Starburst Lab HJP-17007, manufactured by Sugino Machine Limited) via a pipe, and a pass-type dispersion treatment was performed 30 times until D50 became 100 ⁇ m or less.
• the dispersion treatment was performed using a single nozzle chamber with a nozzle diameter of 0.25 mm and a pressure of 100 MPa.
• the conductive material dispersions (comparative dispersions 1 to 4) produced by adding a defoaming agent all had relatively low viscosity and good storage stability, but had poor complex elastic modulus or phase angle. was there.
• the dispersion particle size was determined by a determination method according to JIS K5600-2-5 using a grind gauge having a maximum groove depth of 300 ⁇ m.
• the concentration of the CNT dispersion was diluted so that the value of the loading index was in the range of 0.8 to 1.2.
• the complex elastic modulus and phase angle of the conductive material dispersion are a strain rate at 25 ° C. and a frequency of 1 Hz using a reometer (RheoStress 1 rotary reometer manufactured by Thermo Fisher Scientific Co., Ltd.) with a cone having a diameter of 35 mm and 2 °. It was evaluated by performing a dynamic viscoelasticity measurement in the range of 0.01% to 5%.
• BT1003M LUCAN BT1003M (manufactured by LG Chem Ltd., multilayer CNT, average outer diameter 13 nm, average fiber diameter 32 ⁇ m, specific surface area 201 m 2 / g) 6A: JENOTUBE6A (manufactured by JEIO, multi-walled CNT, average outer diameter 6 nm, average fiber diameter 58 ⁇ m, specific surface area 700 m 2 / g)
• -TUBALL Single-wall carbon nanotube (made of OCSiAl, average outer diameter 1.7 nm, average fiber diameter 21 ⁇ m, specific surface area 490 m 2 / g)
• TNSR Single-wall carbon nanotube (manufactured by Timesnano, average outer diameter 1.5 nm, average fiber diameter 18 ⁇ m, specific surface area 610 m 2 / g)
• Li-400 Denka Black Li-400 (Denka, acetylene black, average primary
• the mixture of compounds 11, 12, and 13 shown in Table 5 was prepared as follows as a compound produced by deactivating the polymerization initiator without polymerizing. 97 parts of methyl ethyl ketone was charged in a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, replaced with nitrogen gas, and the inside of the reaction vessel was heated to 51 ° C. and held for 15 minutes. Three parts of 2,2'-azobis (2,4-dimethylvaleronitrile) (V-65) were added dropwise, and the mixture was held at 51 ° C. for 4 hours and then dried under reduced pressure at 25 ° C. to obtain a white solid.
• V-65 2,2'-azobis (2,4-dimethylvaleronitrile
• the white solid was analyzed by gas chromatography in the same manner as the analysis of the component (B), and it was confirmed that the white solid contained the chemical formulas 11, 12, and 13. Further, the mixture of compounds 14, 15 and 16 shown in Table 5 was prepared as follows. 97 parts of ion-exchanged water was charged in a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, replaced with nitrogen gas, and the inside of the reaction vessel was heated to 56 ° C. and held for 15 minutes. 3 parts of 2,2'-azobis-2-amidinopropane dihydrochloride (V-50) was added dropwise, and the mixture was kept at 56 ° C. for 4 hours and then allowed to cool.
• V-50 2,2'-azobis-2-amidinopropane dihydrochloride
• the obtained aqueous solution was analyzed by gas chromatography in the same manner as the analysis of the component (B), and it was confirmed that the aqueous solution contained chemical formulas 14, 15 and 16.
• the addition amount of the mixture of the chemical formulas 14, 15 and 16 was converted as a solid content of 3% by mass.
• Example 2-1 ⁇ Preparation of negative electrode mixture composition and negative electrode> (Example 2-1)
• a conductive material dispersion (dispersion 1), CMC, and water are added to a plastic container having a capacity of 150 cm 3 , and then a rotation / revolution mixer (Shinky Awatori Rentaro, ARE-310). ) was stirred at 2,000 rpm for 30 seconds. Then, artificial graphite and silicon were added as the negative electrode active material, and the mixture was stirred at 2,000 rpm for 150 seconds using the above-mentioned rotation / revolution mixer.
• the non-volatile content of the negative electrode mixture composition was 48% by mass.
• the non-volatile content ratio of artificial graphite: silicon: conductive material: CMC: SBR was 87: 10: 0.5: 1: 1.5.
• the obtained negative electrode mixture composition is applied onto a copper foil having a thickness of 20 ⁇ m using an applicator, and then the coating film is dried in an electric oven at 120 ° C. ⁇ 5 ° C. for 25 minutes to form an electrode film.
• the electrode film was rolled by a roll press (3t hydraulic roll press manufactured by Thunk Metal) to obtain a negative electrode (negative electrode 1).
• the basis weight per unit of the mixed material layer was 10 mg / cm 2 , and the density of the mixed material layer after the rolling treatment was 1.6 g / cc.
• -Artificial graphite CGB-20 (manufactured by Nippon Graphite Industry), 100% non-volatile content -Silicon: Silicon monoxide (manufactured by Osaka Titanium Technologies, SILICON MONOOXIDE SiO 1.3C 5 ⁇ m), 100% non-volatile content -CMC: Carboxymethyl cellulose # 1190 (manufactured by Daicel FineChem), 100% non-volatile content -SBR: Styrene butadiene rubber TRD2001 (manufactured by JSR), non-volatile content 48%
• Negative electrodes 2 to 16 were obtained by the same method as in Example 2-1 except that the conductive material dispersion was changed to each dispersion (dispersions 2 to 16) shown in Table 6.
• Example 2-17, 2-18 Except that the dispersion 3 and the dispersion 14 or the dispersion 15 were mixed so that the ratio of the carbon-based conductive materials had the composition shown in Table 6 and used as the conductive material dispersion, the same as in Example 2-1.
• a negative electrode 17 and a negative electrode 18 were obtained by the same method.
• Comparative negative electrodes 1 to 4 were obtained by the same method as in Example 2-1 except that the conductive material dispersion was changed to each of the dispersions shown in Table 6 (comparative dispersions 1 to 4).
• Example 3-1 Preparation of mixture composition for positive electrode and positive electrode
• a conductive material dispersion (dispersion 1), CMC, and water are added to a plastic container having a capacity of 150 cm 3 , and then a rotation / revolution mixer (Shinky Awatori Rentaro, ARE-310). ), Stir at 2,000 rpm for 30 seconds, then add LFP as the positive electrode active material, and use a rotation / revolution mixer (Sinky Awatori Rentaro, ARE-310) to 150 at 2,000 rpm. Stir for seconds.
• PTFE was added, and the mixture was stirred at 2,000 rpm for 30 seconds using a rotation / revolution mixer (Awatori Rentaro manufactured by Shinky, ARE-310) to obtain a positive electrode mixture composition.
• the non-volatile content of the mixture composition for the positive electrode was 75% by mass.
• the non-volatile content ratio of LFP: conductive material: PTFE: CMC was 97: 0.5: 1: 1.5.
• the positive electrode mixture composition was applied onto an aluminum foil having a thickness of 20 ⁇ m using an applicator, and then dried in an electric oven at 120 ° C. ⁇ 5 ° C. for 25 minutes to prepare an electrode film. Then, the electrode film was rolled by a roll press (3t hydraulic roll press manufactured by Thunk Metal) to obtain a positive electrode (positive electrode 1).
• the basis weight per unit of the mixed material layer was 20 mg / cm 2 , and the density of the mixed material layer after the rolling treatment was 2.1 g / cc.
• -LFP Lithium iron phosphate HED (trademark) LFP-400 (manufactured by BASF, 100% non-volatile content)
• PTFE Polytetrafluoroethylene Polyflon PTFE D-210C (manufactured by Daikin, 60% non-volatile content)
• CMC Carboxymethyl cellulose # 1190 (manufactured by Daicel FineChem, 100% non-volatile content)
• Example 3-2 to 3-16 Positive electrodes 2 to 16 were obtained by the same method as in Example 3-1 except that the conductive material dispersion was changed to each dispersion (dispersions 2 to 16) shown in Table 7.
• Examples 3-17 and 3-18 Except that the dispersion 3 and the dispersion 14 or the dispersion 15 were mixed so that the ratio of the carbon-based conductive materials had the composition shown in Table 7 and used as the conductive material dispersion, the same as in Example 3-1.
• a positive electrode 17 and a positive electrode 18 were obtained by the same method.
• Comparative positive electrodes 1 to 4 were obtained by the same method as in Example 3-1 except that the conductive material dispersions were changed to the respective dispersions (comparative dispersions 1 to 4) shown in Table 7.
• the mixture in the plastic container is mixed using a spatula until uniform, and 4% by mass of PTFE (manufactured by Daikin, 60% by mass of non-volatile content) is added using the above-mentioned rotation / revolution mixer, and the mixture is 2,000 rpm.
• PTFE manufactured by Daikin, 60% by mass of non-volatile content
• the mixture is 2,000 rpm.
• 11.2% by mass of water was added, and the mixture was stirred at 2,000 rpm for 30 seconds using the above-mentioned rotation / revolution mixer.
• the mixture was stirred at 3,000 rpm for 10 minutes to obtain a standard positive electrode mixture composition.
• the above-mentioned standard positive electrode mixture composition was applied onto an aluminum foil having a thickness of 20 ⁇ m as a current collector using an applicator. Then, it was dried in an electric oven at 120 ° C. ⁇ 5 ° C. for 25 minutes to adjust the basis weight per unit area of the electrode to 20 mg / cm 2 . Further, a rolling process was performed by a roll press (3t hydraulic roll press manufactured by Thunk Metal) to prepare a standard positive electrode having a mixture layer density of 2.1 g / cm 3 .
• active materials 87% by mass of artificial graphite (CGB-20, manufactured by Nippon Graphite Industry, 100% non-volatile content), silicon (silicon monoxide, manufactured by Osaka Titanium Technology, SILICON MONOOXIDE SiO 1.3C 5 ⁇ m, 100% non-volatile content) was added in an amount of 10% by mass, and the mixture was stirred at 2,000 rpm for 150 seconds using a rotation / revolution mixer (Awatori Rentaro manufactured by Shinky, ARE-310).
• the above-mentioned standard negative electrode mixture composition is applied to a copper foil having a thickness of 20 ⁇ m as a current collector using an applicator, and then dried in an electric oven at 80 ° C. ⁇ 5 ° C. for 25 minutes to obtain a unit of electrodes.
• the basis weight per area was adjusted to 10 mg / cm 2 .
• a rolling process was performed by a roll press (3t hydraulic roll press manufactured by Thunk Metal) to prepare a standard negative electrode having a mixture layer density of 1.6 g / cm 3 .
• Examples 4-1 to 4-18, Comparative Examples 4-1 to 4-4) Examples 5-1 to 5-18, Comparative Examples 5-1 to 5-4) (Making a secondary battery) Using the negative electrodes and positive electrodes shown in Tables 8 and 9, punching into 50 mm ⁇ 45 mm and 45 mm ⁇ 40 mm, respectively, and inserting a separator (porous polyproprene film) inserted between them into an aluminum laminate bag, and making electricity. It was dried in an oven at 70 ° C. for 1 hour.
• an electrolytic solution (a mixed solvent in which ethylene carbonate, dimethyl carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1: 1 was prepared, and further, vinylene carbonate was prepared as an additive.
• an electrolytic solution a mixed solvent in which ethylene carbonate, dimethyl carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1: 1 was prepared, and further, vinylene carbonate was prepared as an additive.
• a non-aqueous electrolyte solution in which LiPF 6 was dissolved at a concentration of 1M
• the aluminum laminate was sealed, and the negative electrode evaluation batteries 1 to 1 to each were used. 18.
• Negative electrode evaluation comparative batteries 1 to 4 positive electrode evaluation batteries 1 to 18, and positive electrode evaluation comparative batteries 1 to 4 were produced.
• the obtained negative electrode evaluation secondary battery and positive electrode evaluation secondary battery were installed in a constant temperature room at 25 ° C., and charge / discharge measurements were performed using a charge / discharge device (Hokuto Denko, SM-8). After performing constant current constant voltage charging (cutoff current 1mA (0.02C)) at a charging end voltage of 4.3V at a charging current of 10mA (0.2C), discharge at a discharge current of 10mA (0.2C). A constant current discharge was performed with a cutoff voltage of 3 V.
• Rate characteristics 3C discharge capacity / 3rd 0.2C discharge capacity x 100 (%) ⁇ Judgment criteria> ⁇ : 80% or more (excellent) ⁇ : 60% or more and less than 80% (good) ⁇ : Less than 60% (defective)
• the obtained negative electrode evaluation secondary battery and positive electrode evaluation secondary battery were installed in a constant temperature room at 25 ° C., and charge / discharge measurements were performed using a charge / discharge device (Hokuto Denko, SM-8). After performing constant current constant voltage charging (cutoff current 2.5mA (0.05C)) at a charging end voltage of 4.3V at a charging current of 25mA (0.5C), a discharge current of 25mA (0.5C). , Constant current discharge was performed with a discharge cutoff voltage of 3 V. This operation was repeated 200 times.
• the cycle characteristics can be expressed by the ratio of the third 0.5C discharge capacity and the 200th 0.5C discharge capacity at 25 ° C., and the following formula 2.
• Cycle characteristics 3rd 0.5C discharge capacity / 200th 0.5C discharge capacity x 100 (%) ⁇ Judgment criteria> ⁇ : 85% or more (excellent) ⁇ : 80% or more and less than 85% (good) ⁇ : Less than 80% (defective)

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