WO2019004216A1 - Binder composition for electrochemical element electrode, slurry composition for electrochemical element electrode, electrochemical element electrode, electrochemical element, and method for manufacturing electrochemical element electrode - Google Patents

Binder composition for electrochemical element electrode, slurry composition for electrochemical element electrode, electrochemical element electrode, electrochemical element, and method for manufacturing electrochemical element electrode Download PDF

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Publication number
WO2019004216A1
WO2019004216A1 PCT/JP2018/024204 JP2018024204W WO2019004216A1 WO 2019004216 A1 WO2019004216 A1 WO 2019004216A1 JP 2018024204 W JP2018024204 W JP 2018024204W WO 2019004216 A1 WO2019004216 A1 WO 2019004216A1
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Prior art keywords
electrode
polymer
electrochemical element
mixture layer
binder composition
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PCT/JP2018/024204
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French (fr)
Japanese (ja)
Inventor
麻貴 召田
園部　健矢
高橋　直樹
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日本ゼオン株式会社
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Priority to JP2019526939A priority Critical patent/JP7156281B2/en
Publication of WO2019004216A1 publication Critical patent/WO2019004216A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-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 OR LIGHT-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
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
    • 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
    • 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

  • the present invention relates to a binder composition for an electrochemical element electrode, a slurry composition for an electrochemical element electrode, an electrode for an electrochemical element, an electrochemical element, and a method for producing an electrode for an electrochemical element.
  • Electrochemical devices such as lithium ion secondary batteries and electric double layer capacitors are characterized by their small size, light weight, high energy density, and capable of repeated charge and discharge, and are used in a wide range of applications.
  • an electrode for a lithium ion secondary battery usually includes a current collector and an electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer) formed on the current collector.
  • the electrode mixture layer is formed by, for example, applying a slurry composition containing an electrode active material, a binder composition containing a binder, and the like on a current collector, and drying the applied slurry composition. It is formed.
  • Patent Document 1 the negative electrode peel strength is increased by preparing a negative electrode for lithium ion secondary battery using hydrogenated carboxy-modified rubber as a binder, and the high-rate discharge characteristics of the lithium ion secondary battery and Improve cycle characteristics.
  • Patent Document 2 the peel strength of the battery electrode plate is enhanced by using a carboxy-modified rubber as a binder and a base as a dispersant to increase the peel strength of the battery electrode plate, and thus the cycle characteristics of the battery can be improved. I am improving.
  • the present invention provides a binder composition for an electrochemical element electrode and a slurry composition for an electrochemical element electrode, which can make the electrode mixture layer firmly adhere to a current collector while easily densifying the electrode mixture layer. Intended to provide.
  • Another object of the present invention is to provide an electrode for an electrochemical device which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics to the electrochemical device, and a method of manufacturing the electrode for the electrochemical device. I assume.
  • Another object of the present invention is to provide an electrochemical device having high capacity and excellent cycle characteristics.
  • the present inventors diligently studied for the purpose of solving the above-mentioned problems. And, the present inventor is high if a binder composition containing a nitrile group-containing monomer and a polymer obtained by polymerizing at least two kinds of aliphatic conjugated diene monomers is used as a binder. The inventors have found that it is possible to form an electrode mixture layer that is dense and can be firmly adhered to a current collector, and the present invention has been completed.
  • the present invention aims to solve the above-mentioned problems advantageously, and the binder composition for an electrochemical element electrode of the present invention is a binder composition for an electrochemical element electrode containing a polymer.
  • the polymer is characterized in that it contains a nitrile group-containing monomer unit and at least two aliphatic conjugated diene monomer units.
  • containing a monomer unit means that "the polymer obtained by using the monomer contains a repeating unit derived from the monomer”.
  • the aliphatic conjugated diene monomer unit contains an aliphatic conjugated diene monomer unit having 5 or more and 12 or less carbon atoms. If the polymer contains, as an aliphatic conjugated diene monomer unit, a repeating unit derived from an aliphatic conjugated diene monomer having 5 or more and 12 or less carbon atoms, easy densification and current collection of the electrode mixture layer Strong adherence to the body can be achieved at an even higher level.
  • the proportion of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms in the polymer is 1% to 50% by mass. Is preferred. If the polymer contains an aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms in the above ratio, the electrode mixture layer can be easily densified and firmly adhered to the current collector. It can be achieved at a high level.
  • the “proportion of monomer unit” formed by polymerizing a certain monomer is usually It corresponds to the ratio (feed ratio) of a certain monomer concerned to all the monomers used for polymerization of combination.
  • the “proportion of monomer units” in the polymer can be measured using nuclear magnetic resonance (NMR) methods such as 1 H-NMR and 13 C-NMR.
  • the binder composition for electrochemical element electrodes of this invention it is preferable that the said aliphatic conjugated diene monomer unit contains a 1, 3- butadiene unit.
  • the polymer contains a repeating unit derived from 1,3-butadiene as an aliphatic conjugated diene monomer unit, the electrode mixture layer can be more easily densified.
  • the proportion of the 1,3-butadiene unit in the polymer is preferably 1% by mass or more and 50% by mass or less. If the polymer contains 1,3-butadiene units in the above proportion, easy densification of the electrode mixture layer and strong adhesion to the current collector can be achieved at a still higher level.
  • the ratio of the said nitrile group containing monomeric unit in the said polymer is 20 to 85 mass%. If the polymer contains a nitrile group-containing monomer unit in the above proportion, easy densification of the electrode mixture layer and strong adhesion to the current collector can be achieved at a still higher level. In addition, the affinity of the polymer to the organic solvent (in particular, a polar organic solvent such as N-methylpyrrolidone) is secured, and a binder composition in which the polymer is well dissolved in the organic solvent can be obtained.
  • the organic solvent in particular, a polar organic solvent such as N-methylpyrrolidone
  • the aliphatic conjugated diene monomer unit is an aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms and a 1,3-butadiene unit.
  • the ratio of the ratio of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms to the ratio of the 1,3-butadiene unit in the polymer is 0.02 to 50. preferable.
  • the polymer contains both aliphatic conjugated diene monomer units having 5 or more and 12 or less carbon atoms and 1,3-butadiene units, and has 5 or more carbon atoms with respect to the proportion of 1,3-butadiene units in the polymer If the ratio of the ratio of aliphatic conjugated diene monomer units of 12 or less is within the above range, easy densification of the electrode mixture layer and firm adhesion to the current collector can be achieved at a still higher level. can do.
  • the slurry composition for electrochemical element electrodes of this invention is an electrode active material, The binder composition for electrochemical element electrodes mentioned above Or any one of the above.
  • the electrode mixture layer is formed using the slurry composition containing any of the binder compositions described above, the electrode mixture layer is made to adhere firmly to the current collector while the density of the electrode mixture layer is easily increased. be able to.
  • an electrode provided with the electrode compound material layer obtained using the above-mentioned slurry composition is used, high capacity-ization of an electrochemical element can be performed, and the cycle characteristic excellent in an electrochemical element can be exhibited.
  • the electrode active material is preferably an electrode active material containing nickel.
  • the capacity of the electrochemical device can be further increased.
  • the electrode for electrochemical element of this invention was formed using either of the slurry composition for electrochemical element electrodes mentioned above It is characterized by including an electrode mixture layer. As described above, by using any of the above-described slurry compositions, it is possible to produce an electrode which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics of the electrochemical device.
  • Another object of the present invention is to advantageously solve the above-mentioned problems, and an electrochemical device of the present invention comprises the above-mentioned electrode for an electrochemical device.
  • an electrochemical device of the present invention comprises the above-mentioned electrode for an electrochemical device.
  • the manufacturing method of the electrode for electrochemical elements of this invention collects any of the slurry composition for electrochemical element electrodes mentioned above Applying on a current collector, drying the slurry composition for an electrochemical element electrode applied on the current collector, and forming a pre-press electrode mixture layer on the current collector; Roll pressing the pre-press electrode mixture layer at a linear pressure of 500 kN / cm or more and 3000 kN / cm or less to obtain a post-press electrode mixture layer.
  • linear pressure is a value obtained by dividing the load (kN) applied to the pre-press electrode mixture layer during roll pressing by the width (cm) of the pre-press electrode mixture layer. It is.
  • a binder composition for an electrochemical element electrode and a slurry composition for an electrochemical element electrode capable of firmly adhering the electrode mixture layer to a current collector while easily densifying the electrode mixture layer. can be provided. Further, according to the present invention, it is possible to provide an electrode for an electrochemical device which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics to the electrochemical device, and a method of manufacturing the electrode for the electrochemical device. Can. Furthermore, according to the present invention, it is possible to provide an electrochemical device having high capacity and excellent cycle characteristics.
  • the binder composition for an electrochemical element electrode of the present invention can be used when preparing the slurry composition for an electrochemical element electrode of the present invention.
  • the slurry composition for an electrochemical device electrode of the present invention prepared using the binder composition for an electrochemical device electrode of the present invention is, for example, a method for producing an electrode for an electrochemical device of the present invention. It can be used when producing the electrode for an electrochemical element of the invention.
  • the electrochemical element of the present invention is characterized by using the electrode for an electrochemical element of the present invention produced using the slurry composition for an electrochemical element electrode of the present invention.
  • the binder composition of the present invention contains a polymer, and optionally further contains other components that can be incorporated into the electrode of the electrochemical device.
  • the binder composition of the present invention can further contain a solvent.
  • the polymer contained in the binder composition of the present invention comprises a nitrile group-containing monomer unit and at least two aliphatic conjugated diene monomer units.
  • the binder composition of this invention contains the polymer mentioned above as a binder, if the electrode compound material layer of the electrode for electrochemical elements is formed using the said binder composition, electrode compound material It is possible to make the layer firmly adhere to the current collector while easily densifying the layer.
  • the binder composition of the present invention contains an aliphatic conjugated diene monomer unit which can reduce the glass transition temperature and contribute to the improvement of the flexibility of the polymer.
  • a polymer is compounded components, such as an electrode active material and a electrically conductive material, by forming an aliphatic conjugated diene monomer unit using not only 1 type individually but 2 types or more of aliphatic conjugated diene monomers
  • the affinity with (especially, carbon-based materials) is enhanced, and in the slurry composition prepared using the binder composition, those compounding components can be well dispersed.
  • a high application density can be realized.
  • the slurry composition containing a polymer which is excellent in flexibility and can disperse the blended components well the components do not become unevenly distributed in forming the electrode mixture layer, and for example, relatively low line Even when roll pressing is performed by pressure, the electrode mixture layer can be well adhered to the current collector while sufficiently increasing the density of the obtained electrode mixture layer.
  • the polymer contained in the binder composition of the present invention is excellent in strength because it contains not only the above-mentioned aliphatic conjugated diene monomer units but also nitrile group-containing monomer units. Since the polymer having such excellent strength exhibits high binding property, the electrode mixture layer can be firmly adhered to the current collector by using the binder composition containing the polymer.
  • the polymer does not release the component contained in the electrode mixture layer from the electrode mixture layer Hold (ie, act as a binder).
  • the polymer contains a nitrile group-containing monomer unit and contains at least two aliphatic conjugated diene monomer units. That is, the polymer contains repeating units derived from at least one nitrile group-containing monomer and repeating units derived from at least two aliphatic conjugated diene monomers.
  • the polymer A can optionally contain repeating units (other repeating units) other than the nitrile group-containing monomer unit and the aliphatic conjugated diene monomer unit.
  • nitrile group-containing monomer unit examples include ⁇ , ⁇ -ethylenically unsaturated nitrile monomers.
  • the ⁇ , ⁇ -ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an ⁇ , ⁇ -ethylenically unsaturated compound having a nitrile group, for example, acrylonitrile; ⁇ -chloroacrylonitrile, Examples thereof include ⁇ -halogeno acrylonitriles such as ⁇ -bromoacrylonitrile; ⁇ -alkyl acrylonitriles such as methacrylonitrile and ⁇ -ethyl acrylonitrile; and the like.
  • acrylonitrile and methacrylonitrile are preferable as the nitrile group-containing monomer from the viewpoint of improving the output characteristics of the electrochemical device while making the electrode mixture layer more firmly adhere to the current collector.
  • a nitrile group containing monomer can be used individually or in combination of 2 or more types.
  • the proportion of the nitrile group-containing monomer unit contained in the polymer is preferably 20% by mass or more, and 40% by mass or more, based on 100% by mass of all repeating units of the polymer. More preferably, it is more preferably 50% by mass or more, particularly preferably 60% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, and 75% by mass or less It is further preferred that If the proportion of the nitrile group-containing monomer unit in the polymer is 20% by mass or more, the electrode mixture layer is more firmly adhered to the current collector to further improve the cycle characteristics of the electrochemical device. it can.
  • the affinity of the polymer to the organic solvent (in particular, a polar organic solvent such as N-methylpyrrolidone) is secured, and a binder composition in which the polymer is well dissolved in the organic solvent can be obtained.
  • the proportion of the nitrile group-containing monomer unit in the polymer is 85% by mass or less, the flexibility of the polymer can be secured without excessively increasing the glass transition temperature. Therefore, a sufficiently densified electrode mixture layer can be easily formed.
  • the aliphatic conjugated diene monomer unit is formed of two or more aliphatic conjugated diene monomers. And although it does not specifically limit as an aliphatic conjugated diene monomer which can form an aliphatic conjugated diene monomer unit, For example, C5-C12 aliphatic conjugated diene monomer (C5-12) Aliphatic conjugated diene monomers) and 1,3-butadiene.
  • aliphatic conjugated diene monomer having 5 to 12 carbon atoms 2-methyl-1,3-butadiene (isoprene, carbon number: 5), 2,3-dimethyl-1,3-butadiene (carbon) The number of atoms: 6) and the like can be mentioned, and among these, isoprene is preferable. If the polymer contains an aliphatic conjugated diene monomer unit having 5 or more and 12 or less carbon atoms derived from an aliphatic conjugated diene monomer having 5 or more and 12 or less carbon atoms, the flexibility of the polymer is secured. Ru.
  • the presence of a hydrophobic group (such as a methyl group) present on a carbon atom having a double bond improves the affinity of the polymer to the compounding component (particularly, carbon material). And the blended components can be dispersed better.
  • a slurry composition in which the compounding components are dispersed more satisfactorily on the current collector a higher application density can be realized.
  • each component does not become unevenly distributed, and it is obtained even when, for example, roll pressing is performed at a relatively low linear pressure.
  • the electrode mixture layer can be more closely adhered to the current collector while the density of the resulting electrode mixture layer is further increased. Therefore, easy densification of the electrode mixture layer and strong adhesion to the current collector can be achieved at a still higher level.
  • the aliphatic conjugated diene monomer having 5 to 12 carbon atoms can be used alone or in combination of two or more.
  • the proportion of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms contained in the polymer is preferably 1% by mass or more, more preferably 5% by mass or more, and 15% by mass. % Or more is more preferable, 50% by mass or less is preferable, and 25% by mass or less is more preferable. If the proportion of aliphatic conjugated diene monomer units having 5 or more and 12 or less carbon atoms in the polymer is 1% by mass or more, the flexibility of the polymer is improved and the blending components (in particular, the carbon material) The affinity with the resin is improved to further increase the coating density. Therefore, easy densification of the electrode mixture layer and firm adhesion to the current collector can be achieved at a still higher level.
  • the electrode mixture layer can be well adhered to the current collector.
  • the glass transition temperature is lowered to sufficiently secure the flexibility of the polymer, thereby increasing the density of the electrode assembly.
  • the material layer can be formed more easily.
  • the proportion of 1,3-butadiene units contained in the polymer is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 7% by mass or more. It is preferable that it is mass% or less, It is more preferable that it is 25 mass% or less, It is still more preferable that it is 15 mass% or less. If the proportion of 1,3-butadiene units in the polymer is 1% by mass or more, a sufficiently densified electrode mixture layer can be easily formed.
  • the proportion of 1,3-butadiene units in the polymer is 50% by mass or less, excessive softening of the polymer due to a significant decrease in the glass transition temperature is suppressed, so the electrode mixture layer Can be well adhered to the current collector.
  • the aliphatic conjugated diene monomer has 5 to 12 carbon atoms. It is preferable to use together the aliphatic conjugated diene monomer of the following and 1,3-butadiene, and it is more preferable to use isoprene and 1,3-butadiene together. That is, the polymer preferably contains both aliphatic conjugated diene monomer units having 5 to 12 carbon atoms and 1,3-butadiene units, and contains both isoprene units and 1,3-butadiene units. Is more preferred.
  • the ratio of the aliphatic conjugated diene monomer units contained in the polymer is 100% by mass of all repeating units of the polymer.
  • the content is preferably 15% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, preferably 80% by mass or less, and 60% by mass or less Is more preferable, and 50% by mass or less is even more preferable. If the proportion of the aliphatic conjugated diene monomer unit in the polymer is 15% by mass or more, the flexibility of the polymer can be secured without excessively increasing the glass transition temperature. Therefore, a sufficiently densified electrode mixture layer can be easily formed.
  • the electrode mixture layer is more firmly adhered to the current collector to further improve the cycle characteristics of the electrochemical device. It can be done.
  • the ratio of the amount of the aliphatic conjugated diene monomer unit in the total amount of the nitrile group-containing monomer unit and the aliphatic conjugated diene monomer unit contained in the polymer is 15% by mass or more Is more preferably 20% by mass or more, preferably 80% by mass or less, more preferably 60% by mass or less, and still more preferably 40% by mass or less.
  • the proportion of the aliphatic conjugated diene monomer unit in the total of the nitrile group-containing monomer unit and the aliphatic conjugated diene monomer unit is 15% by mass or more, a sufficiently densified electrode mixture layer is obtained It can be easily formed, and if it is 80% by mass or less, excessive softening of the polymer due to a significant reduction of the glass transition temperature is suppressed, so the electrode mixture layer can be favorably used as a current collector. It can be attached closely.
  • the electrolytic solution of the polymer is 15% by mass to 80% by mass, the electrolytic solution of the polymer The degree of swelling in the medium (degree of electrolyte swelling) is well controlled, and the polymer exhibits good binding in the electrolyte. Therefore, the cycle characteristics of the electrochemical device can be further enhanced.
  • the ratio of the ratio of aliphatic conjugated diene monomer units having 5 or more and 12 or less carbon atoms to the ratio of 1,3-butadiene units in the polymer is preferably 0.02 or more, and 0. It is more preferably 5 or more, still more preferably 1 or more, particularly preferably more than 1 and preferably 50 or less, more preferably 10 or less, and 5 or less More preferably, it is particularly preferably 4 or less. If the ratio of the ratio of aliphatic conjugated diene monomer units having 5 to 12 carbon atoms to the ratio of 1,3-butadiene units is 0.02 or more, the flexibility of the polymer is improved, and the blending components Affinity with (especially, carbon material) is improved and coating density is increased.
  • the electrode mixture layer can be well adhered to the current collector.
  • the other repeating units that the polymer may optionally contain are not particularly limited.
  • the polymer may contain, as a repeating unit, an alkylene structural unit obtained by hydrogenating the above-mentioned aliphatic conjugated diene monomer unit.
  • the other repeating units contained in the polymer are 0% by mass or more and 10% by mass or less from the viewpoint of achieving a high level of easy densification of the electrode mixture layer and strong adhesion to the current collector.
  • the content is preferably 0% by mass to 5% by mass, and more preferably 0% by mass to 2% by mass.
  • the polymer can be produced, for example, by polymerizing a monomer composition containing the above-described monomer in an aqueous solvent.
  • the content ratio of each monomer in the monomer composition can be determined according to the content ratio of the monomer unit (repeating unit) in the polymer.
  • the aqueous solvent is not particularly limited as long as the polymer can be dispersed, and water may be used alone, or a mixed solvent of water and another solvent may be used.
  • the polymerization mode is not particularly limited, and any mode such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method can be used.
  • any method such as ionic polymerization, radical polymerization, living radical polymerization can be used, for example.
  • an emulsifier, a dispersant, a polymerization initiator, a polymerization auxiliary and the like used for the polymerization those generally used can be used, and the amount thereof used is also the amount generally used.
  • the electrolyte solution swelling degree of the polymer prepared as described above is usually 100% or more, preferably 110% or more, preferably 500% or less, and 300% or less. Is more preferred.
  • the degree of electrolyte swelling of the polymer is 110% or more, the affinity of the polymer to the organic solvent as well as the electrolyte can be ensured, and a binder composition in which the polymer is favorably dissolved in the organic solvent can be obtained.
  • the degree of swelling of the polymer in the electrolyte is 500% or less, the polymer can easily maintain its binding property in the electrolyte and can exhibit excellent characteristics (particularly cycle characteristics) in the electrochemical device. it can.
  • the “electrolyte swelling degree” can be measured using the method described in the examples of the present specification.
  • organic solvent for example, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, amyl alcohol and the like; Ketones such as methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and butyl acetate; ethers such as diethyl ether, dioxane and tetrahydrofuran; N, N-dimethylformamide, N, N-dimethyl acetamide, N-methyl pyrrolidone (NMP) Amide-based polar organic solvents such as N; N; N-dimethylformamide, N, N-dimethyl acetamide, N-methyl pyrrolidone (NMP)
  • the binder composition in addition to the above components, contains components such as a binder other than the predetermined polymer, a conductive material, a reinforcing material, a leveling agent, a viscosity modifier, an electrolytic solution additive and the like. May be These are not particularly limited and known ones such as those described in WO 2012/115096 can be used. Moreover, these components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
  • the binder composition of the present invention can be prepared by mixing the above-mentioned components by known methods.
  • the organic solvent is contained as a solvent by replacing the aqueous solvent with the organic solvent by a known method and adding other components as necessary. Binder compositions can be prepared.
  • the slurry composition for an electrochemical element electrode of the present invention is a slurry-like composition containing at least an electrode active material and the above-mentioned binder composition for an electrochemical element electrode of the present invention.
  • the electrode active material, the above-described polymer, and the above-described other components optionally blended are usually dissolved and / or dispersed in the above-described solvent. It is a composition.
  • the slurry composition of this invention contains the binder composition of this invention mentioned above, if an electrode compound material layer is formed using the slurry composition of this invention, an electrode compound material layer will be easily made high. It can be made to adhere firmly to the current collector while densifying.
  • the electrode active material is a substance that transfers electrons at the electrode of the electrochemical device. And it is preferable that the slurry composition of this invention contains the electrode active material (Hereafter, it may abbreviate as a "Ni containing electrode active material.") Containing nickel as an electrode active material. If an electrode containing a Ni-containing electrode active material is used, the capacity of the electrochemical device can be further increased.
  • the Ni-containing electrode active material can be particularly suitably used as a positive electrode active material in a non-aqueous secondary battery such as a lithium ion secondary battery.
  • Ni-containing electrode active material Li (Ni x Co y M (1-x-y)) in O 2 [formula (A), M is manganese (Mn), magnesium (Mg ), Zirconium (Zr), molybdenum (Mo), tungsten (W), aluminum (Al), chromium (Cr), vanadium (V), cerium (Ce), titanium (Ti), iron (Fe), potassium (K) And at least one selected from the group consisting of gallium (Ga) and indium (In), and x and y satisfy the following relational expressions: 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, x + y ⁇ 1. ]
  • the lithium containing complex oxide represented by these can be used.
  • formula (A1) Li (Ni x Co y Al (1-x-y)) O 2 [ wherein (A1 In the above, x and y satisfy the relational expressions of 0.30 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 0.7, x + y ⁇ 1. ]
  • the lithium containing complex oxide represented by these is more preferable.
  • the formula (A2) Li (Ni x Co y Mn (1-x-y)) O
  • x and y satisfy the following relational expressions: 0.30 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 0.7, x + y ⁇ 1.
  • the lithium containing complex oxide represented by these is more preferable.
  • Electrode active material an electrode active material other than the above-described Ni-containing electrode active material can also be used.
  • the slurry composition for electrochemical element electrodes is a slurry composition for lithium ion secondary battery electrodes is demonstrated as an example below, this invention is not limited to the following examples.
  • lithium-containing cobalt oxide LiCoO 2
  • lithium manganate LiMn 2 O 4
  • olivine-type lithium iron phosphate examples include LiFePO 4 ), lithium olivine-type manganese phosphate (LiMnPO 4 ), and lithium excess spinel compounds represented by Li 1 + x Mn 2-x O 4 (0 ⁇ x ⁇ 2).
  • the compounding quantity and particle diameter of a positive electrode active material are not specifically limited, It can be made to be the same as that of the positive electrode active material used conventionally.
  • a negative electrode active material for lithium ion secondary batteries a carbon type negative electrode active material, a metal type negative electrode active material, and the negative electrode active material which combined these, etc. are mentioned, for example.
  • the carbon-based negative electrode active material refers to an active material having carbon as a main skeleton capable of inserting lithium (also referred to as "doping"), and as the carbon-based negative electrode active material, for example, a carbonaceous material and graphite Quality materials.
  • the carbonaceous material for example, graphitizable carbon, non-graphitizable carbon having a structure close to an amorphous structure represented by glassy carbon and the like can be mentioned.
  • the graphitizable carbon for example, a carbon material using a tar pitch obtained from petroleum or coal as a raw material can be mentioned. Specific examples thereof include coke, mesocarbon microbeads (MCMB), mesophase pitch carbon fibers, and pyrolytic vapor grown carbon fibers.
  • non-graphitizable carbon for example, a phenol resin fired body, polyacrylonitrile carbon fiber, quasi-isotropic carbon, a furfuryl alcohol resin fired body (PFA), hard carbon and the like can be mentioned.
  • graphite material natural graphite, artificial graphite, etc. are mentioned, for example.
  • artificial graphite for example, artificial graphite obtained by heat treating carbon containing graphitizable carbon mainly at 2800 ° C. or higher, graphitized MCMB obtained by heat treating MCMB at 2000 ° C. or higher, mesophase pitch carbon fiber The graphitized mesophase pitch carbon fiber etc. which were heat-treated above are mentioned.
  • the metal-based negative electrode active material is an active material containing a metal, and usually contains an element capable of inserting lithium in its structure, and the theoretical electric capacity per unit mass when lithium is inserted is 500 mAh / An active material of g or more.
  • the metal-based active material for example, lithium metal, a single metal capable of forming a lithium alloy (for example, Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn) , Sr, Zn, Ti, etc.) and their alloys, and oxides, sulfides, nitrides, silicides, carbides, phosphides, etc. thereof.
  • a silicon-containing active material silicon-based negative electrode active material
  • the capacity of the lithium ion secondary battery can be increased.
  • the silicon-based negative electrode active material includes, for example, silicon (Si), an alloy containing silicon, SiO, SiO x , a composite of a Si-containing material obtained by coating or compounding a Si-containing material with conductive carbon and conductive carbon Etc. These silicon-based negative electrode active materials may be used alone or in combination of two or more. In addition, the compounding quantity and particle diameter of a negative electrode active material are not specifically limited, It can be made to be the same as that of the negative electrode active material used conventionally.
  • Binder composition As a binder composition, the binder composition for electrochemical element electrodes of this invention containing the polymer mentioned above is used.
  • the content ratio of the binder composition in the slurry composition for an electrochemical element electrode is preferably such an amount that the amount of the polymer is 0.5 parts by mass or more per 100 parts by mass of the electrode active material,
  • the amount is preferably not less than 0 parts by mass, more preferably not less than 1.5 parts by mass, and preferably not less than 4.0 parts by mass, 3.0 parts by mass It is more preferable that the amount be less than or equal to parts, and even more preferable that the amount be less than or equal to 2.5 parts by mass.
  • the binder composition when the binder composition is contained in the slurry composition so that the amount of the polymer is 4.0 parts by mass or less, the ratio of the electrode active material in the electrode mixture layer is secured to achieve electrochemistry.
  • the capacitance of the device can be sufficiently increased.
  • ⁇ Other ingredients examples include, without being particularly limited, the same components as the other components that can be added to the above-described binder composition.
  • the other components may be used alone or in combination of two or more at an arbitrary ratio.
  • the above-described slurry composition can be prepared by mixing the above-described components. Specifically, the above components are optionally added using a mixer such as a ball mill, sand mill, bead mill, pigment disperser, leash crusher, ultrasonic disperser, homogenizer, planetary mixer, film mix, etc.
  • the slurry composition can be prepared by mixing with a solvent.
  • a solvent arbitrarily added in preparation of a slurry composition the same thing as the solvent described by the term of the binder composition can be used.
  • the electrode for an electrochemical device of the present invention includes, for example, an electrode mixture layer formed using the above-described slurry composition for an electrochemical device electrode on a current collector.
  • the electrode mixture layer is usually made of a dried product of the above-mentioned slurry composition for an electrochemical element electrode, and the electrode mixture layer optionally includes at least an electrode active material, the above-described polymer, and , And other ingredients are contained.
  • each component contained in the electrode mixture layer is contained in the said slurry composition for electrochemical element electrodes, The suitable abundance ratio of these each component is in a slurry composition. It is the same as the preferred abundance ratio of each component.
  • the electrode compound material layer is formed using the slurry composition for electrochemical element electrodes mentioned above, the electrochemical element is made using the electrode for said electrochemical element. If manufactured, it is possible to obtain an electrochemical device having high capacity and excellent cycle characteristics.
  • the electrode for an electrochemical device of the present invention described above can be produced, for example, using the method for producing an electrode for an electrochemical device of the present invention.
  • the method for producing an electrode of the present invention comprises the steps of applying the above-described slurry composition of the present invention onto a current collector (coating step), and drying the slurry composition applied on the current collector.
  • a step (drying step) of forming a pre-press electrode mixture layer on the body and roll pressing of the pre-press electrode mixture layer at a linear pressure of 500 kN / cm or more and 3000 kN / cm or less are performed.
  • the method for applying the slurry composition onto the current collector is not particularly limited, and any known method can be used. Specifically, as a coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brushing method, or the like can be used. At this time, the slurry composition may be applied to only one side of the current collector, or may be applied to both sides. The thickness of the slurry film on the current collector after application and before drying can be appropriately set according to the desired thickness of the electrode mixture layer.
  • a current collector to which the slurry composition is applied a material having electrical conductivity and electrochemical durability is used.
  • a current collector for example, a current collector made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum or the like can be used.
  • the said material may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
  • the method for drying the slurry composition on the current collector is not particularly limited, and any known method can be used, such as hot air, hot air, drying with low humidity, vacuum drying, infrared rays, electron beam, etc.
  • the drying method by irradiation is mentioned.
  • the linear pressure at the time of roll-pressing the pre-press electrode mixture layer on the current collector needs to be 500 kN / cm or more and 3000 kN / cm or less, preferably 1000 kN / cm or more, 2500 kN / cm It is preferable that it is the following. Since the pre-press electrode mixture layer on the current collector is formed of the slurry composition of the present invention, a high-density post-press electrode mixture can be easily compressed if the linear pressure is 500 kN / cm or more. You can get a layer. In addition, when the linear pressure is 3000 kN / cm or less, the electrode active material is not excessively destroyed by the press.
  • the roll temperature at the time of roll-pressing is 25 degreeC or more and 150 degrees C or less normally.
  • the conveyance speed of the laminated body of the electrode compound material layer before a press, and a collector at the time of roll-pressing is 5 m / min or more and 100 m / min or less normally.
  • the number of times of roll press may be two or more, it is usually one.
  • the electrochemical device of the present invention is not particularly limited, and is a lithium ion secondary battery or an electric double layer capacitor, preferably a lithium ion secondary battery. And since the electrochemical device of the present invention is provided with the electrode for an electrochemical device of the present invention, it has a high capacity and excellent cycle characteristics.
  • the lithium ion secondary battery as the electrochemical device of the present invention generally comprises an electrode (positive electrode and negative electrode), an electrolytic solution, and a separator, and uses the electrode of the present invention for at least one of the positive electrode and the negative electrode. .
  • Electrode other than the electrode for an electrochemical device described above which can be used for a lithium ion secondary battery as an electrochemical device of the present invention known electrodes can be used without particular limitation.
  • an electrode other than the electrode for an electrochemical element described above an electrode formed by forming an electrode mixture layer on a current collector using a known manufacturing method can be used.
  • an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used.
  • a supporting electrolyte of a lithium ion secondary battery for example, a lithium salt is used.
  • lithium salts include LiPF 6 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiSbF 6 , LiAlCl 4 , LiClO 4 , CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi , (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) NLi, and the like.
  • LiPF 6 , LiClO 4 , and CF 3 SO 3 Li are preferable, and LiPF 6 is particularly preferable because they are easily dissolved in a solvent and exhibit a high degree of dissociation.
  • an electrolyte may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Usually, the lithium ion conductivity tends to be higher as the supporting electrolyte having a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of the supporting electrolyte.
  • the organic solvent used for the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte, and examples thereof include dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), Carbonates such as butylene carbonate (BC) and ethyl methyl carbonate (EMC); esters such as ⁇ -butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide Etc. are preferably used. Also, a mixture of these solvents may be used.
  • DMC dimethyl carbonate
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • Carbonates such as butylene carbonate (BC) and ethyl methyl carbonate (EMC)
  • esters such as ⁇ -butyrolactone and methyl formate
  • carbonates because the dielectric constant is high and the stable potential region is wide, and it is more preferable to use a mixture of ethylene carbonate and ethyl methyl carbonate.
  • known additives such as vinylene carbonate (VC), fluoroethylene carbonate (FEC) and ethyl methyl sulfone may be added to the electrolytic solution.
  • the separator is not particularly limited and, for example, those described in JP-A-2012-204303 can be used. Among these, it is possible to reduce the film thickness of the entire separator, thereby increasing the ratio of the electrode active material in the lithium ion secondary battery to increase the capacity per volume, and it is possible to use polyolefin.
  • a microporous membrane made of a resin of a system (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred.
  • the positive electrode and the negative electrode are superimposed via a separator, and this is wound or folded according to the battery shape as needed, and the battery container is , And the electrolyte container is injected into the battery container and sealed.
  • a fuse, an over current protection element such as a PTC element, an expanded metal, a lead plate, etc. may be provided if necessary to prevent the pressure rise inside the lithium ion secondary battery and the occurrence of overcharge and discharge and the like.
  • the shape of the lithium ion secondary battery may be, for example, a coin, a button, a sheet, a cylinder, a square, or a flat.
  • the binder composition for the positive electrode (polymer NMP solution) is applied onto a polytetrafluoroethylene sheet, dried for 0.5 to 3 hours in an environment at a temperature of 80 to 120 ° C., and cast to a thickness of 500 ⁇ m ⁇ 50 ⁇ m. I got a film. The cast film was cut into a square of 1 cm ⁇ 1 cm to obtain a test piece, and the mass of the test piece (mass before immersion A) was measured. Thereafter, the test piece was immersed in an electrolytic solution at a temperature of 60 ° C. for 72 hours.
  • the mixture was dissolved and prepared by adding vinylene carbonate to a concentration of 2% by mass to the mixture after dissolution of LiPF 6 .
  • the test piece after immersion was pulled up, the surface electrolyte solution was wiped off with a towel paper, and then the mass of the test piece (mass after immersion B) was measured. And swelling degree (%) of electrolyte solution was computed using the following formula.
  • Electrolyte swelling degree (%) mass after immersion B / mass before immersion A ⁇ 100 ⁇ Peel strength of positive electrode> The positive electrode was cut out in a rectangular shape of width 1.0 cm ⁇ length 10 cm to obtain a test piece, and this test piece was fixed on a horizontal stand with the positive electrode composite material layer facing up.
  • a cellophane tape was attached to the surface of the positive electrode mixture layer of the test piece, and then the stress when peeling off the cellophane tape from one end of the test piece at a speed of 50 mm / min in a 180 ° direction was measured.
  • a cellophane tape what was prescribed
  • the coating density (g / cm 3 ) was calculated from the thickness (cm) and the coating amount (g / cm 2 ) of the pre-press positive electrode mixture layer of the positive electrode raw fabric using the following formula. The thickness of the positive electrode mixture layer before pressing was measured by a micrometer.
  • Coating density (g / cm 3 ) coating amount (g / cm 2 ) / thickness (cm)
  • the positive electrode material sheet was punched into a circle having a diameter of 1.2 cm to prepare a test piece.
  • the test piece was placed on a flat plate and pressed at a pressure of 9 MPa (press test). Then, the thickness (cm) and the weight (g) of the positive electrode mixture layer after pressing were determined, and the density of the electrode mixture layer was calculated. The thickness of the positive electrode mixture layer after pressing was measured by a micrometer. In addition, the weight of the positive electrode mixture layer after pressing was calculated by subtracting the weight of the current collector from the weight of the test piece after pressing. This press test was performed 10 times, and the average value of the obtained values was used as a press density (g / cm 3 ), and evaluated based on the following criteria.
  • press density is 3.8 g / cm 3 or more
  • B press density is 3.7 g / cm 3 or more 3.8 g / cm 3 less
  • C less than the press density of 3.6 g / cm 3 or more 3.7 g / cm 3
  • D Press density is 3.5 g / cm 3 or more and less than 3.6 g / cm 3
  • E Press density is less than 3.5 g / cm 3 ⁇ cycle characteristics of lithium ion secondary battery> The obtained lithium ion secondary battery was aged at 60 ° C.
  • Capacity retention rate is 84% or more
  • B Capacity retention rate is 82% or more and less than 84%
  • C Capacity retention rate is 80% or more and less than 82%
  • D Capacity retention rate is 77% or more and less than 80%
  • E Capacity retention rate Less than 77%
  • Example 1 Preparation of Polymer and Binder Composition for Positive Electrode>
  • 10.0 parts of 1,3-butadiene as aliphatic conjugated diene monomer and 20.0 parts of isoprene 70.0 parts of acrylonitrile as nitrile group-containing monomer
  • t-dodecyl mercaptan 0.4 Parts
  • 132 parts of ion exchange water 3 parts of sodium dodecylbenzene sulfonate
  • 0.5 parts of sodium salt of ⁇ -naphthalenesulfonic acid formalin condensate 0.3 parts of potassium persulfate
  • 0.05 parts of ethylenediaminetetraacetic acid sodium salt The polymerization was carried out while maintaining the polymerization temperature at 15.degree.
  • a 20 ⁇ m thick aluminum foil was prepared as a current collector.
  • the positive electrode slurry composition prepared as described above was applied to one surface of an aluminum foil so that the applied amount after drying was about 22 mg / cm 2 .
  • the coated film on aluminum foil is dried at 80 ° C. for 20 minutes and 120 ° C. for 20 minutes, and then heat treated at 150 ° C. for 2 hours to obtain a positive electrode original fabric comprising a pre-pressing negative electrode mixture layer and a current collector.
  • the This positive electrode material sheet was roll pressed at a linear pressure of 2000 kN / cm to produce a positive electrode including a positive electrode mixture layer having a density of 3.7 g / cm 3 on one side of the current collector.
  • ⁇ Fabrication of negative electrode> Mixture of 90 parts of spherical artificial graphite (volume average particle diameter: 12 ⁇ m) and 10 parts of SiO x (volume average particle diameter: 10 ⁇ m) as negative electrode active material, styrene butadiene rubber as binder (number average particle diameter: 180 nm Glass transition temperature: 10 ° C.) 1 part, carboxymethyl cellulose 1 part as a thickener, and an appropriate amount of water were stirred by a planetary mixer to prepare a slurry composition for a negative electrode. Next, a copper foil with a thickness of 15 ⁇ m was prepared as a current collector.
  • the negative electrode slurry composition prepared as described above was applied to one side of a copper foil so that the applied amount after drying was 12 mg / cm 2 . Then, the coated film on the copper foil was dried at 50 ° C. for 20 minutes and 110 ° C. for 20 minutes, and then heat-treated at 150 ° C. for 2 hours to obtain a negative electrode original fabric.
  • the negative electrode material sheet was rolled by a roll press to prepare a negative electrode including a negative electrode mixture layer having a density of 1.8 g / cm 3 on one side of the current collector.
  • the produced positive electrode and negative electrode were wound with a 20- ⁇ m-thick separator (microporous polypropylene film) interposed therebetween, using a core having a diameter of 20 mm, to obtain a wound body.
  • the positive electrode and the negative electrode were disposed such that the positive electrode mixture layer and the negative electrode mixture layer faced each other with the separator interposed therebetween.
  • the obtained winding body was compressed from one direction to a thickness of 4.5 mm at a speed of 10 mm / sec.
  • the winding body after compression was carrying out the planar view ellipse, and ratio (long diameter / short diameter) of the major axis and minor axis was 7.7.
  • LiPF 6 was dissolved in the mixture after the addition of FEC to a concentration of 1.0 M.
  • an electrolytic solution was prepared by adding vinylene carbonate to the mixture after the dissolution of LiPF 6 so as to have a concentration of 2% by mass.
  • the winding body after compression was accommodated in the aluminum lamination case with 3.2 g of electrolyte solution.
  • a lead wire was connected to a predetermined portion of the negative electrode, and a lead wire was connected to a predetermined portion of the positive electrode, and then the opening of the case was sealed with heat to obtain a lithium ion secondary battery.
  • the lithium ion secondary battery was a pouch having a width of 35 mm, a height of 48 mm, and a thickness of 5 mm, and the nominal capacity of the battery was 720 mAh.
  • Examples 2 to 7 An NMP solution of a polymer (binder composition for positive electrode), slurry composition for positive electrode, positive electrode, negative electrode in the same manner as Example 1 except that the monomer composition described in Table 1 was adopted at the time of preparation of the polymer. , And a lithium ion secondary battery.
  • the analysis by NMR method is performed in the same manner as in Example 1, and the ratio of a certain monomer unit in the polymer is the certain monomer in the whole monomers used for the polymerization of the polymer. It confirmed that it matched with the ratio (feed ratio) of.
  • Example 3 An aqueous dispersion of a polymer was prepared in the same manner as in Example 1 except that the monomer composition described in Table 1 was adopted at the preparation of the polymer. And although solvent substitution to NMP was performed like Example 1, a polymer did not dissolve in NMP. Even when such a binder composition for a positive electrode was used, it was clear that a lithium ion secondary battery exhibiting excellent performance could not be obtained, so no positive electrode, negative electrode and lithium ion secondary battery were produced. . The items of the degree of swelling of the electrolyte of the polymer were evaluated.
  • the coating density is increased. It can be seen that the electrode mixture layer can be sufficiently densified. Further, in Examples 1 to 7, it is understood that the electrode mixture layer can be closely adhered to the current collector, and the lithium ion secondary battery can exhibit sufficiently excellent cycle characteristics.
  • Comparative Example 2 using a binder composition containing a nitrile group-containing monomer unit but containing a polymer containing only an isoprene unit as an aliphatic conjugated diene monomer unit, the high density of the electrode mixture layer To be difficult to And, in Comparative Example 3 using a binder composition containing a polymer containing two aliphatic conjugated diene monomer units but not containing a nitrile group-containing monomer unit, as described above, the polymer is The positive electrode, the negative electrode, and the lithium ion secondary battery were not manufactured because they were not dissolved in NMP.
  • a binder composition for an electrochemical element electrode and a slurry composition for an electrochemical element electrode capable of firmly adhering the electrode mixture layer to a current collector while easily densifying the electrode mixture layer. can be provided. Further, according to the present invention, it is possible to provide an electrode for an electrochemical device which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics to the electrochemical device, and a method of manufacturing the electrode for the electrochemical device. Can. Furthermore, according to the present invention, it is possible to provide an electrochemical device having high capacity and excellent cycle characteristics.

Abstract

The purpose of the present invention is to provide a binder composition for an electrochemical element electrode, the binder composition firmly bonding an electrode mixture layer to a collector while easily densifying the electrode mixture layer. This binder composition is for an electrochemical element electrode and contains a polymer, wherein the polymer includes a nitrile group-containing monomer unit, and at least two kinds of aliphatic conjugated diene monomer units.

Description

電気化学素子電極用バインダー組成物、電気化学素子電極用スラリー組成物、電気化学素子用電極、および電気化学素子、並びに電気化学素子用電極の製造方法Binder composition for electrochemical device electrode, slurry composition for electrochemical device electrode, electrode for electrochemical device, electrochemical device, and method for producing electrode for electrochemical device
　本発明は、電気化学素子電極用バインダー組成物、電気化学素子電極用スラリー組成物、電気化学素子用電極、および電気化学素子、並びに電気化学素子用電極の製造方法に関するものである。 The present invention relates to a binder composition for an electrochemical element electrode, a slurry composition for an electrochemical element electrode, an electrode for an electrochemical element, an electrochemical element, and a method for producing an electrode for an electrochemical element.
　リチウムイオン二次電池や電気二重層キャパシタなどの電気化学素子は、小型で軽量、且つ、エネルギー密度が高く、更に繰り返し充放電が可能という特性があり、幅広い用途に使用されている。 Electrochemical devices such as lithium ion secondary batteries and electric double layer capacitors are characterized by their small size, light weight, high energy density, and capable of repeated charge and discharge, and are used in a wide range of applications.
　ここで、例えばリチウムイオン二次電池用の電極は、通常、集電体と、集電体上に形成された電極合材層（正極合材層または負極合材層）とを備えている。そして、この電極合材層は、例えば、電極活物質と、結着材を含むバインダー組成物などとを含むスラリー組成物を集電体上に塗布し、塗布したスラリー組成物を乾燥させることにより形成される。 Here, for example, an electrode for a lithium ion secondary battery usually includes a current collector and an electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer) formed on the current collector. The electrode mixture layer is formed by, for example, applying a slurry composition containing an electrode active material, a binder composition containing a binder, and the like on a current collector, and drying the applied slurry composition. It is formed.
　そこで、近年では、電気化学素子の更なる性能の向上を達成すべく、電極合材層の形成に用いられるバインダー組成物の改良が試みられている（例えば、特許文献１および２参照）。
　特許文献１では、結着材として、水素添加されたカルボキシ変性ゴムを用いてリチウムイオン二次電池用負極を作製することで、負極剥離強度を高めて、リチウムイオン二次電池のハイレート放電特性およびサイクル特性を向上させている。
　特許文献２では、結着材としてカルボキシ変性ゴムを用い、且つ分散剤として塩基を用いて電池用電極板を作製することで、当該電池用電極板の剥離強度を高めて、電池のサイクル特性を向上させている。 Therefore, in recent years, in order to achieve further improvement of the performance of the electrochemical device, improvement of a binder composition used for forming an electrode mixture layer has been attempted (see, for example, Patent Documents 1 and 2).
In Patent Document 1, the negative electrode peel strength is increased by preparing a negative electrode for lithium ion secondary battery using hydrogenated carboxy-modified rubber as a binder, and the high-rate discharge characteristics of the lithium ion secondary battery and Improve cycle characteristics.
In Patent Document 2, the peel strength of the battery electrode plate is enhanced by using a carboxy-modified rubber as a binder and a base as a dispersant to increase the peel strength of the battery electrode plate, and thus the cycle characteristics of the battery can be improved. I am improving.
特開平１１－１１１２６８号公報Japanese Patent Application Laid-Open No. 11-111268 特開２０１３－８９５２８号公報JP, 2013-89528, A
　ここで近年、電気化学素子には、一層の高容量化が求められている。電気化学素子の容量を高めるためには、集電体上の電極合材層が高密度化および高膜厚化された電極を用いる手法が有効である。しかしながら、上記従来のバインダー組成物を用いて電極合材層を形成するに際し、電極合材層の高密度化を達成すべくプレス処理を行っても、十分な高密度化を達成することは困難であった。
　また、上記従来のバインダー組成物を用いて電極合材層を形成するに際し、電極合材層を高膜厚化すると、電極合材層に含まれる電極活物質等の成分が電極合材層から脱離し易くなるという問題もあった。このような電極合材層を備える電極を用いると、電気化学素子のサイクル特性が損なわれる虞がある。
　すなわち、上記従来のバインダー組成物には、電極合材層を容易に高密度化すると共に、電極合材層を集電体に強固に密着させるという点において、改善の余地があった。 Here, in recent years, there has been a demand for higher capacity of electrochemical devices. In order to increase the capacity of the electrochemical device, it is effective to use an electrode in which the electrode mixture layer on the current collector is densified and thickened. However, when forming an electrode mixture layer using the above-mentioned conventional binder composition, it is difficult to achieve sufficient densification even if pressing is performed to achieve densification of the electrode mixture layer. Met.
Moreover, when forming an electrode mixture layer using the above-mentioned conventional binder composition, when the electrode mixture layer is thickened, components such as an electrode active material contained in the electrode mixture layer are extracted from the electrode mixture layer There is also a problem that it becomes easy to detach. When an electrode including such an electrode mixture layer is used, the cycle characteristics of the electrochemical device may be impaired.
That is, the conventional binder composition has room for improvement in that the electrode mixture layer is easily densified and the electrode mixture layer is firmly adhered to the current collector.
　そこで、本発明は、電極合材層を容易に高密度化しつつ、当該電極合材層を集電体に強固に密着させうる電気化学素子電極用バインダー組成物および電気化学素子電極用スラリー組成物を提供することを目的とする。
　また、本発明は、電気化学素子を高容量化しうり、且つ当該電気化学素子に優れたサイクル特性を発揮させうる電気化学素子用電極および当該電気化学素子用電極の製造方法を提供することを目的とする。
　更に、本発明は、高容量であると共に、サイクル特性に優れる電気化学素子を提供することを目的とする。 Therefore, the present invention provides a binder composition for an electrochemical element electrode and a slurry composition for an electrochemical element electrode, which can make the electrode mixture layer firmly adhere to a current collector while easily densifying the electrode mixture layer. Intended to provide.
Another object of the present invention is to provide an electrode for an electrochemical device which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics to the electrochemical device, and a method of manufacturing the electrode for the electrochemical device. I assume.
Another object of the present invention is to provide an electrochemical device having high capacity and excellent cycle characteristics.
　本発明者は、上記課題を解決することを目的として鋭意検討を行った。そして、本発明者は、結着材として、ニトリル基含有単量体と、少なくとも２種の脂肪族共役ジエン単量体を重合して得られる重合体を含有するバインダー組成物を用いれば、高密度であると共に集電体に強固に密着し得る電極合材層を形成可能であることを見出し、本発明を完成させた。 The present inventors diligently studied for the purpose of solving the above-mentioned problems. And, the present inventor is high if a binder composition containing a nitrile group-containing monomer and a polymer obtained by polymerizing at least two kinds of aliphatic conjugated diene monomers is used as a binder. The inventors have found that it is possible to form an electrode mixture layer that is dense and can be firmly adhered to a current collector, and the present invention has been completed.
　即ち、この発明は、上記課題を有利に解決することを目的とするものであり、本発明の電気化学素子電極用バインダー組成物は、重合体を含有する電気化学素子電極用バインダー組成物であって、前記重合体が、ニトリル基含有単量体単位と、少なくとも２種の脂肪族共役ジエン単量体単位とを含むことを特徴とする。上述の組成を有する重合体を含有するバインダー組成物を用いれば、電極合材層を容易に高密度化しつつ、当該電極合材層を集電体に強固に密着させることができる。そして、上述の組成を有する重合体を含有するバインダー組成物を用いて得られる電極合材層を備える電極を使用すれば、電気化学素子を高容量化しうり、且つ電気化学素子に優れたサイクル特性を発揮させることができる。
　なお、本発明において、「単量体単位を含む」とは、「その単量体を用いて得た重合体中に単量体由来の繰り返し単位が含まれている」ことを意味する。 That is, the present invention aims to solve the above-mentioned problems advantageously, and the binder composition for an electrochemical element electrode of the present invention is a binder composition for an electrochemical element electrode containing a polymer. The polymer is characterized in that it contains a nitrile group-containing monomer unit and at least two aliphatic conjugated diene monomer units. By using a binder composition containing a polymer having the above-described composition, the electrode mixture layer can be firmly adhered to the current collector while the electrode mixture layer is easily densified. And, if an electrode comprising an electrode mixture layer obtained using a binder composition containing a polymer having the above composition is used, the capacity of the electrochemical device can be increased, and the cycle characteristics excellent for the electrochemical device Can be demonstrated.
In the present invention, "containing a monomer unit" means that "the polymer obtained by using the monomer contains a repeating unit derived from the monomer".
　ここで、本発明の電気化学素子電極用バインダー組成物は、前記脂肪族共役ジエン単量体単位が、炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位を含むことが好ましい。重合体が、脂肪族共役ジエン単量体単位として、炭素原子数５以上１２以下の脂肪族共役ジエン単量体由来の繰り返し単位を含めば、電極合材層の容易な高密度化および集電体への強固な密着を、更に高いレベルで達成することができる。 Here, in the binder composition for an electrochemical element according to the present invention, it is preferable that the aliphatic conjugated diene monomer unit contains an aliphatic conjugated diene monomer unit having 5 or more and 12 or less carbon atoms. If the polymer contains, as an aliphatic conjugated diene monomer unit, a repeating unit derived from an aliphatic conjugated diene monomer having 5 or more and 12 or less carbon atoms, easy densification and current collection of the electrode mixture layer Strong adherence to the body can be achieved at an even higher level.
　また、本発明の電気化学素子電極用バインダー組成物は、前記重合体中の前記炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合が、１質量％以上５０質量％以下であることが好ましい。重合体が上述の割合で炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位を含めば、電極合材層の容易な高密度化および集電体への強固な密着を、より一層高いレベルで達成することができる。
　なお、本発明において、複数種類の単量体を共重合して製造される重合体において、ある単量体を重合して形成される「単量体単位の割合」は、通常は、その重合体の重合に用いる全単量体に占める当該ある単量体の比率(仕込み比)と一致する。また、本発明において、重合体中における「単量体単位の割合」は、１Ｈ－ＮＭＲおよび１３Ｃ－ＮＭＲなどの核磁気共鳴（ＮＭＲ）法を用いて測定することができる。 In the binder composition for an electrochemical element according to the present invention, the proportion of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms in the polymer is 1% to 50% by mass. Is preferred. If the polymer contains an aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms in the above ratio, the electrode mixture layer can be easily densified and firmly adhered to the current collector. It can be achieved at a high level.
In the present invention, in the polymer produced by copolymerizing a plurality of types of monomers, the “proportion of monomer unit” formed by polymerizing a certain monomer is usually It corresponds to the ratio (feed ratio) of a certain monomer concerned to all the monomers used for polymerization of combination. In the present invention, the “proportion of monomer units” in the polymer can be measured using nuclear magnetic resonance (NMR) methods such as 1 H-NMR and 13 C-NMR.
　そして、本発明の電気化学素子電極用バインダー組成物は、前記脂肪族共役ジエン単量体単位が、１，３－ブタジエン単位を含むことが好ましい。重合体が、脂肪族共役ジエン単量体単位として、１，３－ブタジエン由来の繰り返し単位を含めば、電極合材層を一層容易に高密度化することができる。 And as for the binder composition for electrochemical element electrodes of this invention, it is preferable that the said aliphatic conjugated diene monomer unit contains a 1, 3- butadiene unit. When the polymer contains a repeating unit derived from 1,3-butadiene as an aliphatic conjugated diene monomer unit, the electrode mixture layer can be more easily densified.
　更に、本発明の電気化学素子電極用バインダー組成物は、前記重合体中の前記１，３－ブタジエン単位の割合が、１質量％以上５０質量％以下であることが好ましい。重合体が上述の割合で１，３－ブタジエン単位を含めば、電極合材層の容易な高密度化および集電体への強固な密着を、更に高いレベルで達成することができる。 Furthermore, in the binder composition for an electrochemical element according to the present invention, the proportion of the 1,3-butadiene unit in the polymer is preferably 1% by mass or more and 50% by mass or less. If the polymer contains 1,3-butadiene units in the above proportion, easy densification of the electrode mixture layer and strong adhesion to the current collector can be achieved at a still higher level.
　ここで、本発明の電気化学素子電極用バインダー組成物は、前記重合体中の前記ニトリル基含有単量体単位の割合が、２０質量％以上８５質量％以下であることが好ましい。重合体が上述の割合でニトリル基含有単量体単位を含めば、電極合材層の容易な高密度化および集電体への強固な密着を、更に高いレベルで達成することができる。また、重合体の有機溶媒（特には、Ｎ－メチルピロリドンなどの極性有機溶媒）に対する親和性が確保され、重合体が有機溶媒に良好に溶解したバインダー組成物を得ることができる。 Here, as for the binder composition for electrochemical element electrodes of this invention, it is preferable that the ratio of the said nitrile group containing monomeric unit in the said polymer is 20 to 85 mass%. If the polymer contains a nitrile group-containing monomer unit in the above proportion, easy densification of the electrode mixture layer and strong adhesion to the current collector can be achieved at a still higher level. In addition, the affinity of the polymer to the organic solvent (in particular, a polar organic solvent such as N-methylpyrrolidone) is secured, and a binder composition in which the polymer is well dissolved in the organic solvent can be obtained.
　また、本発明の電気化学素子電極用バインダー組成物は、前記脂肪族共役ジエン単量体単位が、炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位および１，３－ブタジエン単位を含み、前記重合体中の前記１，３－ブタジエン単位の割合に対する前記炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合の比が、０．０２以上５０以下であることが好ましい。重合体が炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位と１，３－ブタジエン単位の双方を含み、且つ重合体中の１，３－ブタジエン単位の割合に対する炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合の比が上述の範囲内であれば、電極合材層の容易な高密度化および集電体への強固な密着を、更に高いレベルで達成することができる。 In the binder composition for an electrochemical element according to the present invention, the aliphatic conjugated diene monomer unit is an aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms and a 1,3-butadiene unit. And the ratio of the ratio of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms to the ratio of the 1,3-butadiene unit in the polymer is 0.02 to 50. preferable. The polymer contains both aliphatic conjugated diene monomer units having 5 or more and 12 or less carbon atoms and 1,3-butadiene units, and has 5 or more carbon atoms with respect to the proportion of 1,3-butadiene units in the polymer If the ratio of the ratio of aliphatic conjugated diene monomer units of 12 or less is within the above range, easy densification of the electrode mixture layer and firm adhesion to the current collector can be achieved at a still higher level. can do.
　また、この発明は、上記課題を有利に解決することを目的とするものであり、本発明の電気化学素子電極用スラリー組成物は、電極活物質と、上述した電気化学素子電極用バインダー組成物の何れかとを含むことを特徴とする。このように、上述したバインダー組成物の何れかを含むスラリー組成物を用いて電極合材層を形成すれば、当該電極合材層を容易に高密度化しつつ、集電体に強固に密着させることができる。そして、上述のスラリー組成物を用いて得られる電極合材層を備える電極を使用すれば、電気化学素子を高容量化しうり、且つ電気化学素子に優れたサイクル特性を発揮させることができる。 Moreover, this invention aims at solving the said subject advantageously, The slurry composition for electrochemical element electrodes of this invention is an electrode active material, The binder composition for electrochemical element electrodes mentioned above Or any one of the above. As described above, when the electrode mixture layer is formed using the slurry composition containing any of the binder compositions described above, the electrode mixture layer is made to adhere firmly to the current collector while the density of the electrode mixture layer is easily increased. be able to. And if an electrode provided with the electrode compound material layer obtained using the above-mentioned slurry composition is used, high capacity-ization of an electrochemical element can be performed, and the cycle characteristic excellent in an electrochemical element can be exhibited.
　ここで、本発明の電気化学素子電極用スラリー組成物は、前記電極活物質が、ニッケルを含有する電極活物質であることが好ましい。ニッケルを含有する電極活物質を用いれば、電気化学素子を更に高容量化することができる。 Here, in the slurry composition for an electrochemical element according to the present invention, the electrode active material is preferably an electrode active material containing nickel. By using an electrode active material containing nickel, the capacity of the electrochemical device can be further increased.
　また、この発明は、上記課題を有利に解決することを目的とするものであり、本発明の電気化学素子用電極は、上述した電気化学素子電極用スラリー組成物の何れかを用いて形成した電極合材層を備えることを特徴とする。このように、上述したスラリー組成物の何れかを使用すれば、電気化学素子を高容量化しうり、且つ当該電気化学素子に優れたサイクル特性を発揮させうる電極を作製することができる。 Moreover, this invention aims at solving the said subject advantageously, The electrode for electrochemical element of this invention was formed using either of the slurry composition for electrochemical element electrodes mentioned above It is characterized by including an electrode mixture layer. As described above, by using any of the above-described slurry compositions, it is possible to produce an electrode which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics of the electrochemical device.
　また、この発明は、上記課題を有利に解決することを目的とするものであり、本発明の電気化学素子は、上述した電気化学素子用電極を備えることを特徴とする。このように、上述した電気化学素子用電極を使用すれば、高容量であると共にサイクル特性に優れる電気化学素子が得られる。 Another object of the present invention is to advantageously solve the above-mentioned problems, and an electrochemical device of the present invention comprises the above-mentioned electrode for an electrochemical device. As described above, when the electrode for an electrochemical device described above is used, an electrochemical device having a high capacity and excellent cycle characteristics can be obtained.
　そして、この発明は、上記課題を有利に解決することを目的とするものであり、本発明の電気化学素子用電極の製造方法は、上述した電気化学素子電極用スラリー組成物の何れかを集電体上に塗布する工程と、前記集電体上に塗布された前記電気化学素子電極用スラリー組成物を乾燥して、前記集電体上にプレス前電極合材層を形成する工程と、前記プレス前電極合材層を、５００ｋＮ／ｃｍ以上３０００ｋＮ／ｃｍ以下の線圧でロールプレスして、プレス後電極合材層を得る工程と、を含む。上述したスラリー組成物の何れかを用いる上述した手順を採用すれば、電極合材層を十分に高密度化しつつ、集電体に強固に密着させることができる。
　なお、本発明において、「線圧」とは、ロールプレスの際にプレス前電極合材層にかかる荷重（ｋＮ）を、プレス前電極合材層の幅（ｃｍ）で除して得られる値である。 And this invention aims at solving the said subject advantageously. The manufacturing method of the electrode for electrochemical elements of this invention collects any of the slurry composition for electrochemical element electrodes mentioned above Applying on a current collector, drying the slurry composition for an electrochemical element electrode applied on the current collector, and forming a pre-press electrode mixture layer on the current collector; Roll pressing the pre-press electrode mixture layer at a linear pressure of 500 kN / cm or more and 3000 kN / cm or less to obtain a post-press electrode mixture layer. By employing the above-described procedure using any of the above-described slurry compositions, the electrode mixture layer can be firmly adhered to the current collector while sufficiently densifying the electrode mixture layer.
In the present invention, “linear pressure” is a value obtained by dividing the load (kN) applied to the pre-press electrode mixture layer during roll pressing by the width (cm) of the pre-press electrode mixture layer. It is.
　本発明によれば、電極合材層を容易に高密度化しつつ、当該電極合材層を集電体に強固に密着させうる電気化学素子電極用バインダー組成物および電気化学素子電極用スラリー組成物を提供することができる。
　また、本発明によれば、電気化学素子を高容量化しうり、且つ当該電気化学素子に優れたサイクル特性を発揮させうる電気化学素子用電極および当該電気化学素子用電極の製造方法を提供することができる。
　更に、本発明によれば、高容量であると共に、サイクル特性に優れる電気化学素子を提供することができる。 According to the present invention, a binder composition for an electrochemical element electrode and a slurry composition for an electrochemical element electrode capable of firmly adhering the electrode mixture layer to a current collector while easily densifying the electrode mixture layer. Can be provided.
Further, according to the present invention, it is possible to provide an electrode for an electrochemical device which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics to the electrochemical device, and a method of manufacturing the electrode for the electrochemical device. Can.
Furthermore, according to the present invention, it is possible to provide an electrochemical device having high capacity and excellent cycle characteristics.
　以下、本発明の実施形態について詳細に説明する。
　ここで、本発明の電気化学素子電極用バインダー組成物は、本発明の電気化学素子電極用スラリー組成物を調製する際に用いることができる。そして、本発明の電気化学素子電極用バインダー組成物を用いて調製した本発明の電気化学素子電極用スラリー組成物は、例えば、本発明の電気化学素子用電極の製造方法を使用して、本発明の電気化学素子用電極を作製する際に用いることができる。更に、本発明の電気化学素子は、本発明の電気化学素子電極用スラリー組成物を用いて作製した、本発明の電気化学素子用電極を用いたことを特徴とする。 Hereinafter, embodiments of the present invention will be described in detail.
Here, the binder composition for an electrochemical element electrode of the present invention can be used when preparing the slurry composition for an electrochemical element electrode of the present invention. The slurry composition for an electrochemical device electrode of the present invention prepared using the binder composition for an electrochemical device electrode of the present invention is, for example, a method for producing an electrode for an electrochemical device of the present invention. It can be used when producing the electrode for an electrochemical element of the invention. Furthermore, the electrochemical element of the present invention is characterized by using the electrode for an electrochemical element of the present invention produced using the slurry composition for an electrochemical element electrode of the present invention.
（電気化学素子電極用バインダー組成物）
　本発明のバインダー組成物は、重合体を含み、任意に、電気化学素子の電極に配合され得るその他の成分を更に含有する。また、本発明のバインダー組成物は、溶媒を更に含有することができる。ここで、本発明のバインダー組成物に含まれる上記重合体は、ニトリル基含有単量体単位と、少なくとも２種の脂肪族共役ジエン単量体単位とを含む。
　そして、本発明のバインダー組成物は、結着材として上述した重合体を含有しているので、当該バインダー組成物を用いて電気化学素子用電極の電極合材層を形成すれば、電極合材層を容易に高密度化しつつ、集電体に強固に密着させることができる。
　なお、本発明のバインダー組成物を用いることで、電極合材層の容易な高密度化および集電体への強固な密着を達成可能である理由は定かではないが、以下の通りであると推察される。
　即ち、本発明のバインダー組成物に含有される重合体は、ガラス転移温度を低下させて重合体の柔軟性の向上に寄与しうる脂肪族共役ジエン単量体単位を含む。そして、脂肪族共役ジエン単量体単位を、１種単独でなく２種以上の脂肪族共役ジエン単量体を用いて形成することで、重合体は、電極活物質や導電材などの配合成分（特には、炭素系材料）との親和性が高まり、バインダー組成物を用いて調製されるスラリー組成物中において、それらの配合成分を良好に分散させることができる。このように、配合成分が良好に分散したスラリー組成物を集電体上に塗布すれば、高い塗布密度を実現することができる。更に、柔軟性に優れると共に配合成分を良好に分散させうる重合体を含むスラリー組成物によれば、電極合材層の形成に際し、各成分が偏在することがなく、また、例えば比較的低い線圧でロールプレスした場合であっても、得られる電極合材層の密度を十分に高めつつ、当該電極合材層を集電体に良好に密着させることができる。加えて、本発明のバインダー組成物に含有される重合体は、上述した脂肪族共役ジエン単量体単位のみならず、ニトリル基含有単量体単位を含むため、強度に優れる。このように優れた強度を有する重合体は、高い結着性を発揮するため、当該重合体を含むバインダー組成物を用いれば、電極合材層を集電体に強固に密着させることができる。 (Binder composition for electrochemical device electrode)
The binder composition of the present invention contains a polymer, and optionally further contains other components that can be incorporated into the electrode of the electrochemical device. The binder composition of the present invention can further contain a solvent. Here, the polymer contained in the binder composition of the present invention comprises a nitrile group-containing monomer unit and at least two aliphatic conjugated diene monomer units.
And since the binder composition of this invention contains the polymer mentioned above as a binder, if the electrode compound material layer of the electrode for electrochemical elements is formed using the said binder composition, electrode compound material It is possible to make the layer firmly adhere to the current collector while easily densifying the layer.
In addition, although it is not clear why it is possible to achieve easy densification of the electrode mixture layer and strong adhesion to the current collector by using the binder composition of the present invention, the reason is as follows. It is guessed.
That is, the polymer contained in the binder composition of the present invention contains an aliphatic conjugated diene monomer unit which can reduce the glass transition temperature and contribute to the improvement of the flexibility of the polymer. And a polymer is compounded components, such as an electrode active material and a electrically conductive material, by forming an aliphatic conjugated diene monomer unit using not only 1 type individually but 2 types or more of aliphatic conjugated diene monomers The affinity with (especially, carbon-based materials) is enhanced, and in the slurry composition prepared using the binder composition, those compounding components can be well dispersed. As described above, by applying the slurry composition in which the compounding components are well dispersed on the current collector, a high application density can be realized. Furthermore, according to the slurry composition containing a polymer which is excellent in flexibility and can disperse the blended components well, the components do not become unevenly distributed in forming the electrode mixture layer, and for example, relatively low line Even when roll pressing is performed by pressure, the electrode mixture layer can be well adhered to the current collector while sufficiently increasing the density of the obtained electrode mixture layer. In addition, the polymer contained in the binder composition of the present invention is excellent in strength because it contains not only the above-mentioned aliphatic conjugated diene monomer units but also nitrile group-containing monomer units. Since the polymer having such excellent strength exhibits high binding property, the electrode mixture layer can be firmly adhered to the current collector by using the binder composition containing the polymer.
＜重合体＞
　重合体は、バインダー組成物を用いて調製したスラリー組成物を使用して電極合材層を形成することにより製造した電極において、電極合材層に含まれる成分が電極合材層から脱離しないように保持する（即ち、結着材として機能する）。 <Polymer>
In the electrode produced by forming an electrode mixture layer using a slurry composition prepared using a binder composition, the polymer does not release the component contained in the electrode mixture layer from the electrode mixture layer Hold (ie, act as a binder).
＜＜重合体の組成＞＞
　重合体は、ニトリル基含有単量体単位を含み、且つ、少なくとも２種の脂肪族共役ジエン単量体単位を含む。すなわち、重合体は、少なくとも１種のニトリル基含有単量体に由来する繰り返し単位と、少なくとも２種の脂肪族共役ジエン単量体に由来する繰り返し単位を含む。
　なお、重合体Ａは、任意に、ニトリル基含有単量体単位および脂肪族共役ジエン単量体単位以外の繰り返し単位（その他の繰り返し単位）を含むことができる。 << Composition of polymer >>
The polymer contains a nitrile group-containing monomer unit and contains at least two aliphatic conjugated diene monomer units. That is, the polymer contains repeating units derived from at least one nitrile group-containing monomer and repeating units derived from at least two aliphatic conjugated diene monomers.
In addition, the polymer A can optionally contain repeating units (other repeating units) other than the nitrile group-containing monomer unit and the aliphatic conjugated diene monomer unit.
［ニトリル基含有単量体単位］
　ニトリル基含有単量体単位を形成し得るニトリル基含有単量体としては、α，β－エチレン性不飽和ニトリル単量体が挙げられる。具体的には、α，β－エチレン性不飽和ニトリル単量体としては、ニトリル基を有するα，β－エチレン性不飽和化合物であれば特に限定されないが、例えば、アクリロニトリル；α－クロロアクリロニトリル、α－ブロモアクリロニトリルなどのα－ハロゲノアクリロニトリル；メタクリロニトリル、α－エチルアクリロニトリルなどのα－アルキルアクリロニトリル；などが挙げられる。これらの中でも、電極合材層を集電体に一層強固に密着させつつ、電気化学素子の出力特性を向上させる観点から、ニトリル基含有単量体としては、アクリロニトリルおよびメタクリロニトリルが好ましい。
　なお、ニトリル基含有単量体は、単独で、または、２種以上を組み合わせて用いることができる。 [Nitrile group-containing monomer unit]
Examples of nitrile group-containing monomers capable of forming nitrile group-containing monomer units include α, β-ethylenically unsaturated nitrile monomers. Specifically, the α, β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α, β-ethylenically unsaturated compound having a nitrile group, for example, acrylonitrile; α-chloroacrylonitrile, Examples thereof include α-halogeno acrylonitriles such as α-bromoacrylonitrile; α-alkyl acrylonitriles such as methacrylonitrile and α-ethyl acrylonitrile; and the like. Among these, acrylonitrile and methacrylonitrile are preferable as the nitrile group-containing monomer from the viewpoint of improving the output characteristics of the electrochemical device while making the electrode mixture layer more firmly adhere to the current collector.
In addition, a nitrile group containing monomer can be used individually or in combination of 2 or more types.
　そして、重合体が含有するニトリル基含有単量体単位の割合は、重合体の全繰り返し単位を１００質量％とした場合、２０質量％以上であることが好ましく、４０質量％以上であることがより好ましく、５０質量％以上であることが更に好ましく、６０質量％以上であることが特に好ましく、８５質量％以下であることが好ましく、８０質量％以下であることがより好ましく、７５質量％以下であることが更に好ましい。重合体中のニトリル基含有単量体単位の割合が２０質量％以上であれば、電極合材層を集電体に一層強固に密着させて、電気化学素子のサイクル特性を更に向上させることができる。加えて、有機溶媒（特には、Ｎ－メチルピロリドンなどの極性有機溶媒）に対する重合体の親和性が確保され、重合体が有機溶媒に良好に溶解したバインダー組成物を得ることができる。一方、重合体中のニトリル基含有単量体単位の割合が８５質量％以下であれば、ガラス転移温度が過度に高まることもなく、重合体の柔軟性を確保することができる。そのため、十分に高密度化した電極合材層を容易に形成することができる。 The proportion of the nitrile group-containing monomer unit contained in the polymer is preferably 20% by mass or more, and 40% by mass or more, based on 100% by mass of all repeating units of the polymer. More preferably, it is more preferably 50% by mass or more, particularly preferably 60% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, and 75% by mass or less It is further preferred that If the proportion of the nitrile group-containing monomer unit in the polymer is 20% by mass or more, the electrode mixture layer is more firmly adhered to the current collector to further improve the cycle characteristics of the electrochemical device. it can. In addition, the affinity of the polymer to the organic solvent (in particular, a polar organic solvent such as N-methylpyrrolidone) is secured, and a binder composition in which the polymer is well dissolved in the organic solvent can be obtained. On the other hand, when the proportion of the nitrile group-containing monomer unit in the polymer is 85% by mass or less, the flexibility of the polymer can be secured without excessively increasing the glass transition temperature. Therefore, a sufficiently densified electrode mixture layer can be easily formed.
［脂肪族共役ジエン単量体単位］
　脂肪族共役ジエン単量体単位は、２種以上の脂肪族共役ジエン単量体により形成される。そして、脂肪族共役ジエン単量体単位を形成し得る脂肪族共役ジエン単量体としては、特に限定されないが、例えば、炭素原子数５以上１２以下の脂肪族共役ジエン単量体（Ｃ５～１２脂肪族共役ジエン単量体）、１，３－ブタジエンが挙げられる。 [Aliphatic conjugated diene monomer unit]
The aliphatic conjugated diene monomer unit is formed of two or more aliphatic conjugated diene monomers. And although it does not specifically limit as an aliphatic conjugated diene monomer which can form an aliphatic conjugated diene monomer unit, For example, C5-C12 aliphatic conjugated diene monomer (C5-12) Aliphatic conjugated diene monomers) and 1,3-butadiene.
　炭素原子数５以上１２以下の脂肪族共役ジエン単量体としては、２－メチル－１，３－ブタジエン（イソプレン、炭素原子数：５）、２，３－ジメチル－１，３－ブタジエン（炭素原子数：６）などが挙げられ、これらの中でもイソプレンが好ましい。重合体が、炭素原子数５以上１２以下の脂肪族共役ジエン単量体に由来する炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位を含めば、重合体の柔軟性が確保される。その上、二重結合を有する炭素原子上に存在する疎水性基（メチル基など）の存在によって、重合体の配合成分（特には、炭素材料）に対する親和性が向上するためと推察されるが、配合成分を一層良好に分散させることができる。配合成分が一層良好に分散したスラリー組成物を集電体上に塗布すれば、更に高い塗布密度を実現することができる。加えて、バインダー組成物を含むスラリー組成物を用いた電極合材層の形成に際し、各成分が偏在することがなく、また、例えば比較的低い線圧でロールプレスした場合であっても、得られる電極合材層の密度を更に高めつつ、当該電極合材層を集電体に一層良好に密着させることができる。従って、電極合材層の容易な高密度化および集電体への強固な密着を、更に高いレベルで達成することができる。
　なお、炭素原子数５以上１２以下の脂肪族共役ジエン単量体は、単独で、または、２種以上を組み合わせて用いることができる。 As an aliphatic conjugated diene monomer having 5 to 12 carbon atoms, 2-methyl-1,3-butadiene (isoprene, carbon number: 5), 2,3-dimethyl-1,3-butadiene (carbon) The number of atoms: 6) and the like can be mentioned, and among these, isoprene is preferable. If the polymer contains an aliphatic conjugated diene monomer unit having 5 or more and 12 or less carbon atoms derived from an aliphatic conjugated diene monomer having 5 or more and 12 or less carbon atoms, the flexibility of the polymer is secured. Ru. Furthermore, it is speculated that the presence of a hydrophobic group (such as a methyl group) present on a carbon atom having a double bond improves the affinity of the polymer to the compounding component (particularly, carbon material). And the blended components can be dispersed better. By applying a slurry composition in which the compounding components are dispersed more satisfactorily on the current collector, a higher application density can be realized. In addition, in the formation of the electrode mixture layer using the slurry composition containing the binder composition, each component does not become unevenly distributed, and it is obtained even when, for example, roll pressing is performed at a relatively low linear pressure. The electrode mixture layer can be more closely adhered to the current collector while the density of the resulting electrode mixture layer is further increased. Therefore, easy densification of the electrode mixture layer and strong adhesion to the current collector can be achieved at a still higher level.
The aliphatic conjugated diene monomer having 5 to 12 carbon atoms can be used alone or in combination of two or more.
　そして、重合体が含有する炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合は、１質量％以上であることが好ましく、５質量％以上であることがより好ましく、１５質量％以上であることが更に好ましく、５０質量％以下であることが好ましく、２５質量％以下であることがより好ましい。重合体中の炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合が１質量％以上であれば、重合体の柔軟性が向上する共に、配合成分（特には、炭素材料）との親和性が向上して塗布密度が更に高まる。そのため、電極合材層の容易な高密度化および集電体への強固な密着を更に高いレベルで達成することができる。一方、重合体中の炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合が５０質量％以下であれば、ガラス転移温度が大幅に低下することによる重合体の過度な柔軟化が抑制されるので、電極合材層を集電体へ良好に密着させることができる。 The proportion of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms contained in the polymer is preferably 1% by mass or more, more preferably 5% by mass or more, and 15% by mass. % Or more is more preferable, 50% by mass or less is preferable, and 25% by mass or less is more preferable. If the proportion of aliphatic conjugated diene monomer units having 5 or more and 12 or less carbon atoms in the polymer is 1% by mass or more, the flexibility of the polymer is improved and the blending components (in particular, the carbon material) The affinity with the resin is improved to further increase the coating density. Therefore, easy densification of the electrode mixture layer and firm adhesion to the current collector can be achieved at a still higher level. On the other hand, if the proportion of aliphatic conjugated diene monomer units having 5 or more and 12 or less carbon atoms in the polymer is 50% by mass or less, excessive softening of the polymer due to a significant decrease in the glass transition temperature As a result, the electrode mixture layer can be well adhered to the current collector.
　また、重合体が、１，３－ブタジエンに由来する１，３－ブタジエン単位を含めば、ガラス転移温度が低下することにより重合体の柔軟性が十分に確保されて、高密度化した電極合材層を一層容易に形成することができる。 In addition, if the polymer contains 1,3-butadiene units derived from 1,3-butadiene, the glass transition temperature is lowered to sufficiently secure the flexibility of the polymer, thereby increasing the density of the electrode assembly. The material layer can be formed more easily.
　そして、重合体が含有する１，３－ブタジエン単位の割合は、１質量％以上であることが好ましく、５質量％以上であることがより好ましく、７質量％以上であることが更に好ましく、５０質量％以下であることが好ましく、２５質量％以下であることがより好ましく、１５質量％以下であることが更に好ましい。重合体中の１，３－ブタジエン単位の割合が１質量％以上であれば、十分に高密度化した電極合材層を容易に形成することができる。一方、重合体中の１，３－ブタジエン単位の割合が５０質量％以下であれば、ガラス転移温度が大幅に低下することによる重合体の過度な柔軟化が抑制されるので、電極合材層を集電体へ良好に密着させることができる。 The proportion of 1,3-butadiene units contained in the polymer is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 7% by mass or more. It is preferable that it is mass% or less, It is more preferable that it is 25 mass% or less, It is still more preferable that it is 15 mass% or less. If the proportion of 1,3-butadiene units in the polymer is 1% by mass or more, a sufficiently densified electrode mixture layer can be easily formed. On the other hand, if the proportion of 1,3-butadiene units in the polymer is 50% by mass or less, excessive softening of the polymer due to a significant decrease in the glass transition temperature is suppressed, so the electrode mixture layer Can be well adhered to the current collector.
　ここで、電極合材層の容易な高密度化および集電体への強固な密着をより一層高いレベルで達成する観点からは、脂肪族共役ジエン単量体として、炭素原子数５以上１２以下の脂肪族共役ジエン単量体および１，３－ブタジエンを併用することが好ましく、イソプレンおよび１，３－ブタジエンを併用することがより好ましい。すなわち、重合体は、炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位と１，３－ブタジエン単位の双方を含むことが好ましく、イソプレン単位と１，３－ブタジエン単位の双方を含むことがより好ましい。 Here, from the viewpoint of achieving easy densification of the electrode mixture layer and strong adhesion to the current collector at a higher level, the aliphatic conjugated diene monomer has 5 to 12 carbon atoms. It is preferable to use together the aliphatic conjugated diene monomer of the following and 1,3-butadiene, and it is more preferable to use isoprene and 1,3-butadiene together. That is, the polymer preferably contains both aliphatic conjugated diene monomer units having 5 to 12 carbon atoms and 1,3-butadiene units, and contains both isoprene units and 1,3-butadiene units. Is more preferred.
　また、重合体が含有する脂肪族共役ジエン単量体単位の割合（少なくとも２種の脂肪族共役ジエン単量体単位の割合の合計）は、重合体の全繰り返し単位を１００質量％とした場合、１５質量％以上であることが好ましく、２０質量％以上であることがより好ましく、２５質量％以上であることが更に好ましく、８０質量％以下であることが好ましく、６０質量％以下であることがより好ましく、５０質量％以下であることが更に好ましい。重合体中の脂肪族共役ジエン単量体単位の割合が１５質量％以上であれば、ガラス転移温度が過度に高まることもなく、重合体の柔軟性を確保することができる。そのため、十分に高密度化した電極合材層を容易に形成することができる。一方、重合体中の脂肪族共役ジエン単量体単位の割合が８０質量％以下であれば、電極合材層を集電体に一層強固に密着させて、電気化学素子のサイクル特性を更に向上させることができる。 Further, the ratio of the aliphatic conjugated diene monomer units contained in the polymer (the total of the ratio of at least two types of aliphatic conjugated diene monomer units) is 100% by mass of all repeating units of the polymer. The content is preferably 15% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, preferably 80% by mass or less, and 60% by mass or less Is more preferable, and 50% by mass or less is even more preferable. If the proportion of the aliphatic conjugated diene monomer unit in the polymer is 15% by mass or more, the flexibility of the polymer can be secured without excessively increasing the glass transition temperature. Therefore, a sufficiently densified electrode mixture layer can be easily formed. On the other hand, if the proportion of the aliphatic conjugated diene monomer unit in the polymer is 80% by mass or less, the electrode mixture layer is more firmly adhered to the current collector to further improve the cycle characteristics of the electrochemical device. It can be done.
　そして、重合体が含有するニトリル基含有単量体単位と脂肪族共役ジエン単量体単位の合計量に占める、脂肪族共役ジエン単量体単位の量の割合が、１５質量％以上であることが好ましく、２０質量％以上であることがより好ましく、８０質量％以下であることが好ましく、６０質量％以下であることがより好ましく、４０質量％以下であることが更に好ましい。ニトリル基含有単量体単位と脂肪族共役ジエン単量体単位の合計中の脂肪族共役ジエン単量体単位の割合が１５質量％以上であれば、十分に高密度化した電極合材層を容易に形成することができ、８０質量％以下であれば、ガラス転移温度が大幅に低下することによる重合体の過度な柔軟化が抑制されるので、電極合材層を集電体へ良好に密着させることができる。また、ニトリル基含有単量体単位と脂肪族共役ジエン単量体単位の合計中の脂肪族共役ジエン単量体単位の割合が１５質量％以上８０質量％以下であれば、重合体の電解液中における膨潤度（電解液膨潤度）が良好に制御されて、重合体が電解液中で良好な結着性を発揮する。そのため、電気化学素子のサイクル特性を更に高めることができる。 And the ratio of the amount of the aliphatic conjugated diene monomer unit in the total amount of the nitrile group-containing monomer unit and the aliphatic conjugated diene monomer unit contained in the polymer is 15% by mass or more Is more preferably 20% by mass or more, preferably 80% by mass or less, more preferably 60% by mass or less, and still more preferably 40% by mass or less. If the proportion of the aliphatic conjugated diene monomer unit in the total of the nitrile group-containing monomer unit and the aliphatic conjugated diene monomer unit is 15% by mass or more, a sufficiently densified electrode mixture layer is obtained It can be easily formed, and if it is 80% by mass or less, excessive softening of the polymer due to a significant reduction of the glass transition temperature is suppressed, so the electrode mixture layer can be favorably used as a current collector. It can be attached closely. In addition, when the ratio of the aliphatic conjugated diene monomer unit in the total of the nitrile group-containing monomer unit and the aliphatic conjugated diene monomer unit is 15% by mass to 80% by mass, the electrolytic solution of the polymer The degree of swelling in the medium (degree of electrolyte swelling) is well controlled, and the polymer exhibits good binding in the electrolyte. Therefore, the cycle characteristics of the electrochemical device can be further enhanced.
　加えて、重合体中の１，３－ブタジエン単位の割合に対する炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合の比が、０．０２以上であることが好ましく、０．５以上であることがより好ましく、１以上であることが更に好ましく、１超であることが特に好ましく、５０以下であることが好ましく、１０以下であることがより好ましく、５以下であることが更に好ましく、４以下であることが特に好ましい。１，３－ブタジエン単位の割合に対する炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合の比が０．０２以上であれば、重合体の柔軟性が向上する共に、配合成分（特には、炭素材料）との親和性が向上して塗布密度が高まる。そのため、電極合材層の容易な高密度化および集電体への強固な密着を更に高いレベルで達成することができる。一方、１，３－ブタジエン単位の割合に対する炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の量の割合の比が５０以下であれば、ガラス転移温度が大幅に低下することによる重合体の過度な柔軟化が抑制されるので、電極合材層を集電体へ良好に密着させることができる。 In addition, the ratio of the ratio of aliphatic conjugated diene monomer units having 5 or more and 12 or less carbon atoms to the ratio of 1,3-butadiene units in the polymer is preferably 0.02 or more, and 0. It is more preferably 5 or more, still more preferably 1 or more, particularly preferably more than 1 and preferably 50 or less, more preferably 10 or less, and 5 or less More preferably, it is particularly preferably 4 or less. If the ratio of the ratio of aliphatic conjugated diene monomer units having 5 to 12 carbon atoms to the ratio of 1,3-butadiene units is 0.02 or more, the flexibility of the polymer is improved, and the blending components Affinity with (especially, carbon material) is improved and coating density is increased. Therefore, easy densification of the electrode mixture layer and firm adhesion to the current collector can be achieved at a still higher level. On the other hand, if the ratio of the ratio of the amount of aliphatic conjugated diene monomer units having 5 to 12 carbon atoms to the ratio of 1,3-butadiene units is 50 or less, the glass transition temperature is significantly reduced. Since excessive softening of the polymer is suppressed, the electrode mixture layer can be well adhered to the current collector.
［その他の繰り返し単位］
　重合体が任意に含有し得るその他の繰り返し単位は、特に限定されない。例えば、重合体は、繰り返し単位として、上記脂肪族共役ジエン単量体単位を水素添加して得られるアルキレン構造単位を含んでいてもよい。なお、重合体が含有するその他の繰り返し単位は、電極合材層の容易な高密度化および集電体への強固な密着を高いレベルで達成する観点から、０質量％以上１０質量％以下であることが好ましく、０質量％以上５質量％以下であることがより好ましく、０質量％以上２質量％以下であることが更に好ましい。 [Other repeat unit]
The other repeating units that the polymer may optionally contain are not particularly limited. For example, the polymer may contain, as a repeating unit, an alkylene structural unit obtained by hydrogenating the above-mentioned aliphatic conjugated diene monomer unit. The other repeating units contained in the polymer are 0% by mass or more and 10% by mass or less from the viewpoint of achieving a high level of easy densification of the electrode mixture layer and strong adhesion to the current collector. The content is preferably 0% by mass to 5% by mass, and more preferably 0% by mass to 2% by mass.
＜＜重合体の調製＞＞
　重合体は、例えば上述した単量体を含む単量体組成物を水系溶媒中で重合することにより製造することができる。ここで、本発明において単量体組成物中の各単量体の含有割合は、重合体における単量体単位（繰り返し単位）の含有割合に準じて定めることができる。
　水系溶媒は、重合体が分散可能なものであれば格別限定されず、水を単独で使用してもよいし、水と他の溶媒の混合溶媒を使用してもよい。
　重合様式は、特に限定されず、例えば溶液重合法、懸濁重合法、塊状重合法、乳化重合法などのいずれの様式も用いることができる。重合方法としては、例えばイオン重合、ラジカル重合、リビングラジカル重合などいずれの方法も用いることができる。
　そして、重合に使用される乳化剤、分散剤、重合開始剤、重合助剤などは、一般に用いられるものを使用することができ、その使用量も、一般に使用される量とする。
　なお、上述のようにして調製される重合体の電解液膨潤度は、通常１００％以上であり、１１０％以上であることが好ましく、５００％以下であることが好ましく、３００％以下であることがより好ましい。重合体の電解液膨潤度が１１０％以上であれば、電解液のみならず有機溶媒に対する重合体の親和性が確保され、重合体が有機溶媒に良好に溶解したバインダー組成物を得ることができる。一方、重合体の電解液膨潤度が５００％以下であれば、重合体が電解液中で結着性を保持し易く、電気化学素子に優れた特性（特にはサイクル特性）を発揮させることができる。
　ここで、本発明において、「電解液膨潤度」は、本明細書の実施例に記載の方法を用いて測定することができる。 << Preparation of polymer >>
The polymer can be produced, for example, by polymerizing a monomer composition containing the above-described monomer in an aqueous solvent. Here, in the present invention, the content ratio of each monomer in the monomer composition can be determined according to the content ratio of the monomer unit (repeating unit) in the polymer.
The aqueous solvent is not particularly limited as long as the polymer can be dispersed, and water may be used alone, or a mixed solvent of water and another solvent may be used.
The polymerization mode is not particularly limited, and any mode such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method can be used. As a polymerization method, any method such as ionic polymerization, radical polymerization, living radical polymerization can be used, for example.
And as an emulsifier, a dispersant, a polymerization initiator, a polymerization auxiliary and the like used for the polymerization, those generally used can be used, and the amount thereof used is also the amount generally used.
In addition, the electrolyte solution swelling degree of the polymer prepared as described above is usually 100% or more, preferably 110% or more, preferably 500% or less, and 300% or less. Is more preferred. If the degree of electrolyte swelling of the polymer is 110% or more, the affinity of the polymer to the organic solvent as well as the electrolyte can be ensured, and a binder composition in which the polymer is favorably dissolved in the organic solvent can be obtained. . On the other hand, when the degree of swelling of the polymer in the electrolyte is 500% or less, the polymer can easily maintain its binding property in the electrolyte and can exhibit excellent characteristics (particularly cycle characteristics) in the electrochemical device. it can.
Here, in the present invention, the “electrolyte swelling degree” can be measured using the method described in the examples of the present specification.
＜溶媒＞
　バインダー組成物が含みうる溶媒としては、特に限定されないが、有機溶媒が好ましい。有機溶媒としては、例えば、メタノール、エタノール、ｎ－プロパノール、イソプロパノール、ｎ－ブタノール、イソブタノール、ｔ－ブタノール、ペンタノール、ヘキサノール、ヘプタノール、オクタノール、ノナノール、デカノール、アミルアルコールなどのアルコール類；アセトン、メチルエチルケトン、シクロヘキサノンなどのケトン類；酢酸エチル、酢酸ブチルなどのエステル類；ジエチルエーテル、ジオキサン、テトラヒドロフランなどのエーテル類；Ｎ，Ｎ－ジメチルホルムアミド、Ｎ，Ｎ－ジメチルアセトアミド、Ｎ－メチルピロリドン（ＮＭＰ）などのアミド系極性有機溶媒；Ｎ，Ｎ－ジメチルスルホキシド；トルエン、キシレン、クロロベンゼン、オルトジクロロベンゼン、パラジクロロベンゼンなどの芳香族炭化水素類；などが挙げられる。これらは、１種類を単独で用いてもよいし、２種類以上を混合して用いてもよい。中でも、溶媒としては、ＮＭＰが好ましい。 <Solvent>
Although it does not specifically limit as a solvent which a binder composition may contain, An organic solvent is preferable. As an organic solvent, for example, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, amyl alcohol and the like; Ketones such as methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and butyl acetate; ethers such as diethyl ether, dioxane and tetrahydrofuran; N, N-dimethylformamide, N, N-dimethyl acetamide, N-methyl pyrrolidone (NMP) Amide-based polar organic solvents such as N; N-Dimethyl sulfoxide; Aromatic hydrocarbons such as toluene, xylene, chlorobenzene, ortho-dichlorobenzene and para-dichlorobenzene ; And the like. One of these may be used alone, or two or more of these may be mixed and used. Among them, NMP is preferable as the solvent.
＜その他の成分＞
　バインダー組成物には、上記成分の他に、上記所定の重合体以外の結着材、導電材、補強材、レベリング剤、粘度調整剤、電解液添加剤等の成分をバインダー組成物に含有させてもよい。これらは、特に限定されず公知のもの、例えば国際公開第２０１２／１１５０９６号に記載のものを使用することができる。また、これらの成分は、１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。 <Other ingredients>
In the binder composition, in addition to the above components, the binder composition contains components such as a binder other than the predetermined polymer, a conductive material, a reinforcing material, a leveling agent, a viscosity modifier, an electrolytic solution additive and the like. May be These are not particularly limited and known ones such as those described in WO 2012/115096 can be used. Moreover, these components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
＜バインダー組成物の調製＞
　本発明のバインダー組成物は、上記各成分を既知の方法で混合することにより調製することができる。なお、例えば、重合体を水分散液の状態で調製した場合、既知の方法で水系溶媒を有機溶媒に置換して、必要に応じてその他の成分を添加することで、溶媒として有機溶媒を含むバインダー組成物を調製することができる。 <Preparation of Binder Composition>
The binder composition of the present invention can be prepared by mixing the above-mentioned components by known methods. In addition, for example, when the polymer is prepared in the state of aqueous dispersion, the organic solvent is contained as a solvent by replacing the aqueous solvent with the organic solvent by a known method and adding other components as necessary. Binder compositions can be prepared.
（電気化学素子電極用スラリー組成物）
　本発明の電気化学素子電極用スラリー組成物は、少なくとも、電極活物質と、上述した本発明の電気化学素子電極用バインダー組成物とを含むスラリー状の組成物である。換言すると、本発明のスラリー組成物は、通常、電極活物質と、上述した重合体と、任意に配合される上述したその他の成分とが、上述した溶媒中に溶解および／または分散してなる組成物である。そして、本発明のスラリー組成物は、上述した本発明のバインダー組成物を含んでいるので、本発明のスラリー組成物を用いて電極合材層を形成すれば、電極合材層を容易に高密度化しつつ、集電体に強固に密着させることができる。 (Slurry composition for electrochemical element electrode)
The slurry composition for an electrochemical element electrode of the present invention is a slurry-like composition containing at least an electrode active material and the above-mentioned binder composition for an electrochemical element electrode of the present invention. In other words, in the slurry composition of the present invention, the electrode active material, the above-described polymer, and the above-described other components optionally blended are usually dissolved and / or dispersed in the above-described solvent. It is a composition. And since the slurry composition of this invention contains the binder composition of this invention mentioned above, if an electrode compound material layer is formed using the slurry composition of this invention, an electrode compound material layer will be easily made high. It can be made to adhere firmly to the current collector while densifying.
＜電極活物質＞
　電極活物質は、電気化学素子の電極において電子の受け渡しをする物質である。そして、本発明のスラリー組成物は、電極活物質として、ニッケルを含有する電極活物質（以下、「Ｎｉ含有電極活物質」と略記する場合がある。）を含むことが好ましい。Ｎｉ含有電極活物質を含む電極を用いれば、電気化学素子を更に高容量化することができる。なお、Ｎｉ含有電極活物質は、リチウムイオン二次電池等の非水系二次電池における正極活物質として、特に好適に用いることができる。 <Electrode active material>
The electrode active material is a substance that transfers electrons at the electrode of the electrochemical device. And it is preferable that the slurry composition of this invention contains the electrode active material (Hereafter, it may abbreviate as a "Ni containing electrode active material.") Containing nickel as an electrode active material. If an electrode containing a Ni-containing electrode active material is used, the capacity of the electrochemical device can be further increased. The Ni-containing electrode active material can be particularly suitably used as a positive electrode active material in a non-aqueous secondary battery such as a lithium ion secondary battery.
＜＜Ｎｉ含有電極活物質＞＞
　Ｎｉ含有電極活物質としては、例えば、式（Ａ）：Ｌｉ（ＮｉｘＣｏｙＭ（１－ｘ－ｙ））Ｏ２［式（Ａ）中、Ｍは、マンガン（Ｍｎ）、マグネシウム（Ｍｇ）、ジルコニウム（Ｚｒ）、モリブデン（Ｍｏ）、タングステン（Ｗ）、アルミニウム（Ａｌ）、クロム（Ｃｒ）、バナジウム（Ｖ）、セリウム（Ｃｅ）、チタン（Ｔｉ）、鉄（Ｆｅ）、カリウム（Ｋ）、ガリウム（Ｇａ）、およびインジウム（Ｉｎ）からなる群から選ばれる少なくとも１種であり、ｘおよびｙは、０＜ｘ≦１、０≦ｙ＜１、ｘ＋ｙ≦１の関係式を満たす。］で表されるリチウム含有複合酸化物を用いることができる。 << Ni-containing electrode active material >>
The Ni-containing electrode active material, for example, the formula (A): Li (Ni x Co y M (1-x-y)) in O 2 [formula (A), M is manganese (Mn), magnesium (Mg ), Zirconium (Zr), molybdenum (Mo), tungsten (W), aluminum (Al), chromium (Cr), vanadium (V), cerium (Ce), titanium (Ti), iron (Fe), potassium (K) And at least one selected from the group consisting of gallium (Ga) and indium (In), and x and y satisfy the following relational expressions: 0 <x ≦ 1, 0 ≦ y <1, x + y ≦ 1. ] The lithium containing complex oxide represented by these can be used.
　上記式（Ａ）に該当するものの中でも、電気化学素子の容量をより一層高める観点からは、式（Ａ１）：Ｌｉ（ＮｉｘＣｏｙＡｌ（１－ｘ－ｙ））Ｏ２［式（Ａ１）中、ｘおよびｙは、０．３０≦ｘ≦１、０≦ｙ＜０．７、ｘ＋ｙ≦１の関係式を満たす。］で表されるリチウム含有複合酸化物がより好ましい。また、上記（Ａ）に該当するものの中でも、電気化学素子の容量と安全性をバランス良く向上させる観点からは、式（Ａ２）：Ｌｉ（ＮｉｘＣｏｙＭｎ（１－ｘ－ｙ））Ｏ２［式（Ａ２）中、ｘおよびｙは、０．３０≦ｘ≦１、０≦ｙ＜０．７、ｘ＋ｙ≦１の関係式を満たす。］で表されるリチウム含有複合酸化物がより好ましい。 Among them but corresponding to the above formula (A), from the viewpoint of enhancing the capacity of the electrochemical device further, formula (A1): Li (Ni x Co y Al (1-x-y)) O 2 [ wherein (A1 In the above, x and y satisfy the relational expressions of 0.30 ≦ x ≦ 1, 0 ≦ y <0.7, x + y ≦ 1. ] The lithium containing complex oxide represented by these is more preferable. Further, the inter alia although corresponding (A), the From the viewpoint of the capacity and safety of the electrochemical device with good balance is improved, the formula (A2): Li (Ni x Co y Mn (1-x-y)) O In the formula (A2), x and y satisfy the following relational expressions: 0.30 ≦ x ≦ 1, 0 ≦ y <0.7, x + y ≦ 1. ] The lithium containing complex oxide represented by these is more preferable.
＜＜その他の電極活物質＞＞
　電極活物質としては、上述したＮｉ含有電極活物質以外の電極活物質を用いることもできる。以下では、一例として電気化学素子電極用スラリー組成物がリチウムイオン二次電池電極用スラリー組成物である場合について説明するが、本発明は下記の一例に限定されるものではない。 << Other electrode active materials >>
As the electrode active material, an electrode active material other than the above-described Ni-containing electrode active material can also be used. Although the case where the slurry composition for electrochemical element electrodes is a slurry composition for lithium ion secondary battery electrodes is demonstrated as an example below, this invention is not limited to the following examples.
　リチウムイオン二次電池用の正極活物質としては、上述したＮｉ含有電極活物質に加え、リチウム含有コバルト酸化物（ＬｉＣｏＯ２）、マンガン酸リチウム（ＬｉＭｎ２Ｏ４）、オリビン型リン酸鉄リチウム（ＬｉＦｅＰＯ４）、オリビン型リン酸マンガンリチウム（ＬｉＭｎＰＯ４）、Ｌｉ１＋ｘＭｎ２－ｘＯ４（０＜ｘ＜２）で表されるリチウム過剰のスピネル化合物等の既知の正極活物質が挙げられる。
　なお、正極活物質の配合量や粒子径は、特に限定されることなく、従来使用されている正極活物質と同様とすることができる。 As a positive electrode active material for lithium ion secondary batteries, in addition to the above-described Ni-containing electrode active material, lithium-containing cobalt oxide (LiCoO 2 ), lithium manganate (LiMn 2 O 4 ), olivine-type lithium iron phosphate ( Examples of known positive electrode active materials include LiFePO 4 ), lithium olivine-type manganese phosphate (LiMnPO 4 ), and lithium excess spinel compounds represented by Li 1 + x Mn 2-x O 4 (0 <x <2).
In addition, the compounding quantity and particle diameter of a positive electrode active material are not specifically limited, It can be made to be the same as that of the positive electrode active material used conventionally.
　また、リチウムイオン二次電池用の負極活物質としては、例えば、炭素系負極活物質、金属系負極活物質、およびこれらを組み合わせた負極活物質などが挙げられる。 Moreover, as a negative electrode active material for lithium ion secondary batteries, a carbon type negative electrode active material, a metal type negative electrode active material, and the negative electrode active material which combined these, etc. are mentioned, for example.
　ここで、炭素系負極活物質とは、リチウムを挿入（「ドープ」ともいう。）可能な、炭素を主骨格とする活物質をいい、炭素系負極活物質としては、例えば炭素質材料と黒鉛質材料とが挙げられる。 Here, the carbon-based negative electrode active material refers to an active material having carbon as a main skeleton capable of inserting lithium (also referred to as "doping"), and as the carbon-based negative electrode active material, for example, a carbonaceous material and graphite Quality materials.
　そして、炭素質材料としては、例えば、易黒鉛性炭素や、ガラス状炭素に代表される非晶質構造に近い構造を持つ難黒鉛性炭素などが挙げられる。
　ここで、易黒鉛性炭素としては、例えば、石油または石炭から得られるタールピッチを原料とした炭素材料が挙げられる。具体例を挙げると、コークス、メソカーボンマイクロビーズ（ＭＣＭＢ）、メソフェーズピッチ系炭素繊維、熱分解気相成長炭素繊維などが挙げられる。
　また、難黒鉛性炭素としては、例えば、フェノール樹脂焼成体、ポリアクリロニトリル系炭素繊維、擬等方性炭素、フルフリルアルコール樹脂焼成体（ＰＦＡ）、ハードカーボンなどが挙げられる。 And, as the carbonaceous material, for example, graphitizable carbon, non-graphitizable carbon having a structure close to an amorphous structure represented by glassy carbon and the like can be mentioned.
Here, as the graphitizable carbon, for example, a carbon material using a tar pitch obtained from petroleum or coal as a raw material can be mentioned. Specific examples thereof include coke, mesocarbon microbeads (MCMB), mesophase pitch carbon fibers, and pyrolytic vapor grown carbon fibers.
Moreover, as non-graphitizable carbon, for example, a phenol resin fired body, polyacrylonitrile carbon fiber, quasi-isotropic carbon, a furfuryl alcohol resin fired body (PFA), hard carbon and the like can be mentioned.
　更に、黒鉛質材料としては、例えば、天然黒鉛、人造黒鉛などが挙げられる。
　ここで、人造黒鉛としては、例えば、易黒鉛性炭素を含んだ炭素を主に２８００℃以上で熱処理した人造黒鉛、ＭＣＭＢを２０００℃以上で熱処理した黒鉛化ＭＣＭＢ、メソフェーズピッチ系炭素繊維を２０００℃以上で熱処理した黒鉛化メソフェーズピッチ系炭素繊維などが挙げられる。 Furthermore, as a graphite material, natural graphite, artificial graphite, etc. are mentioned, for example.
Here, as the artificial graphite, for example, artificial graphite obtained by heat treating carbon containing graphitizable carbon mainly at 2800 ° C. or higher, graphitized MCMB obtained by heat treating MCMB at 2000 ° C. or higher, mesophase pitch carbon fiber The graphitized mesophase pitch carbon fiber etc. which were heat-treated above are mentioned.
　また、金属系負極活物質とは、金属を含む活物質であり、通常は、リチウムの挿入が可能な元素を構造に含み、リチウムが挿入された場合の単位質量当たりの理論電気容量が５００ｍＡｈ／ｇ以上である活物質をいう。金属系活物質としては、例えば、リチウム金属、リチウム合金を形成し得る単体金属（例えば、Ａｇ、Ａｌ、Ｂａ、Ｂｉ、Ｃｕ、Ｇａ、Ｇｅ、Ｉｎ、Ｎｉ、Ｐ、Ｐｂ、Ｓｂ、Ｓｉ、Ｓｎ、Ｓｒ、Ｚｎ、Ｔｉなど）およびその合金、並びに、それらの酸化物、硫化物、窒化物、ケイ化物、炭化物、燐化物などが用いられる。これらの中でも、金属系負極活物質としては、ケイ素を含む活物質（シリコン系負極活物質）が好ましい。シリコン系負極活物質を用いることにより、リチウムイオン二次電池を高容量化することができるからである。 The metal-based negative electrode active material is an active material containing a metal, and usually contains an element capable of inserting lithium in its structure, and the theoretical electric capacity per unit mass when lithium is inserted is 500 mAh / An active material of g or more. As the metal-based active material, for example, lithium metal, a single metal capable of forming a lithium alloy (for example, Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn) , Sr, Zn, Ti, etc.) and their alloys, and oxides, sulfides, nitrides, silicides, carbides, phosphides, etc. thereof. Among these, as the metal-based negative electrode active material, a silicon-containing active material (silicon-based negative electrode active material) is preferable. By using the silicon-based negative electrode active material, the capacity of the lithium ion secondary battery can be increased.
　シリコン系負極活物質としては、例えば、ケイ素（Ｓｉ）、ケイ素を含む合金、ＳｉＯ、ＳｉＯｘ、Ｓｉ含有材料を導電性カーボンで被覆または複合化してなるＳｉ含有材料と導電性カーボンとの複合化物などが挙げられる。なお、これらのシリコン系負極活物質は、１種類を単独で用いてもよいし、２種類上を組み合わせて用いてもよい。
　なお、負極活物質の配合量や粒子径は、特に限定されることなく、従来使用されている負極活物質と同様とすることができる。 The silicon-based negative electrode active material includes, for example, silicon (Si), an alloy containing silicon, SiO, SiO x , a composite of a Si-containing material obtained by coating or compounding a Si-containing material with conductive carbon and conductive carbon Etc. These silicon-based negative electrode active materials may be used alone or in combination of two or more.
In addition, the compounding quantity and particle diameter of a negative electrode active material are not specifically limited, It can be made to be the same as that of the negative electrode active material used conventionally.
＜バインダー組成物＞
　バインダー組成物としては、上述した重合体を含有する本発明の電気化学素子電極用バインダー組成物を用いる。 <Binder composition>
As a binder composition, the binder composition for electrochemical element electrodes of this invention containing the polymer mentioned above is used.
　ここで、電気化学素子電極用スラリー組成物中のバインダー組成物の含有割合は、電極活物質１００質量部当たり、重合体の量が０．５質量部以上となる量であることが好ましく、１．０質量部以上となる量であることがより好ましく、１．５質量部以上となる量であることが更に好ましく、４．０質量部以下となる量であることが好ましく、３．０質量部以下となる量であることがより好ましく、２．５質量部以下となる量であることが更に好ましい。スラリー組成物に、重合体の量が０．５質量部以上となる量でバインダー組成物を含有させれば、電極合材層を集電体に一層強固に密着させることができる。一方、スラリー組成物に、重合体の量が４．０質量部以下となるようでバインダー組成物を含有させれば、電極合材層中に占める電極活物質の割合を確保して、電気化学素子の容量を十分に高めることができる。 Here, the content ratio of the binder composition in the slurry composition for an electrochemical element electrode is preferably such an amount that the amount of the polymer is 0.5 parts by mass or more per 100 parts by mass of the electrode active material, The amount is preferably not less than 0 parts by mass, more preferably not less than 1.5 parts by mass, and preferably not less than 4.0 parts by mass, 3.0 parts by mass It is more preferable that the amount be less than or equal to parts, and even more preferable that the amount be less than or equal to 2.5 parts by mass. When the binder composition is contained in the slurry composition in an amount such that the amount of the polymer is 0.5 parts by mass or more, the electrode mixture layer can be more firmly adhered to the current collector. On the other hand, when the binder composition is contained in the slurry composition so that the amount of the polymer is 4.0 parts by mass or less, the ratio of the electrode active material in the electrode mixture layer is secured to achieve electrochemistry. The capacitance of the device can be sufficiently increased.
＜その他の成分＞
　スラリー組成物に配合し得るその他の成分としては、特に限定することなく、上述したバインダー組成物に配合し得るその他の成分と同様のものが挙げられる。また、その他の成分は、１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。 <Other ingredients>
Examples of other components that can be added to the slurry composition include, without being particularly limited, the same components as the other components that can be added to the above-described binder composition. In addition, the other components may be used alone or in combination of two or more at an arbitrary ratio.
＜スラリー組成物の調製＞
　上述したスラリー組成物は、上記各成分を混合することにより調製することができる。具体的には、ボールミル、サンドミル、ビーズミル、顔料分散機、らい潰機、超音波分散機、ホモジナイザー、プラネタリーミキサー、フィルミックスなどの混合機を用いて、上記各成分と、任意に添加される溶媒とを混合することにより、スラリー組成物を調製することができる。なお、スラリー組成物の調製の際に任意に添加される溶媒としては、バインダー組成物の項で記載した溶媒と同じものを使用することができる。 <Preparation of Slurry Composition>
The above-described slurry composition can be prepared by mixing the above-described components. Specifically, the above components are optionally added using a mixer such as a ball mill, sand mill, bead mill, pigment disperser, leash crusher, ultrasonic disperser, homogenizer, planetary mixer, film mix, etc. The slurry composition can be prepared by mixing with a solvent. In addition, as a solvent arbitrarily added in preparation of a slurry composition, the same thing as the solvent described by the term of the binder composition can be used.
（電気化学素子用電極）
　本発明の電気化学素子用電極は、例えば集電体上に、上述した電気化学素子電極用スラリー組成物を用いて形成した電極合材層を備える。具体的に、電極合材層は、通常、上述した電気化学素子電極用スラリー組成物の乾燥物よりなり、電極合材層には、少なくとも、電極活物質と、上述した重合体と、任意に、その他の成分とが含有されている。なお、電極合材層中に含まれている各成分は、上記電気化学素子電極用スラリー組成物中に含まれていたものであり、それら各成分の好適な存在比は、スラリー組成物中の各成分の好適な存在比と同じである。
　そして、本発明の電気化学素子用電極では、上述した電気化学素子電極用スラリー組成物を使用して電極合材層を形成しているので、当該電気化学素子用電極を用いて電気化学素子を製造すれば、高容量であると共にサイクル特性に優れる電気化学素子が得られる。 (Electrode for electrochemical element)
The electrode for an electrochemical device of the present invention includes, for example, an electrode mixture layer formed using the above-described slurry composition for an electrochemical device electrode on a current collector. Specifically, the electrode mixture layer is usually made of a dried product of the above-mentioned slurry composition for an electrochemical element electrode, and the electrode mixture layer optionally includes at least an electrode active material, the above-described polymer, and , And other ingredients are contained. In addition, each component contained in the electrode mixture layer is contained in the said slurry composition for electrochemical element electrodes, The suitable abundance ratio of these each component is in a slurry composition. It is the same as the preferred abundance ratio of each component.
And in the electrode for electrochemical element of this invention, since the electrode compound material layer is formed using the slurry composition for electrochemical element electrodes mentioned above, the electrochemical element is made using the electrode for said electrochemical element. If manufactured, it is possible to obtain an electrochemical device having high capacity and excellent cycle characteristics.
（電気化学素子用電極の製造方法）
　上述した本発明の電気化学素子用電極は、例えば、本発明の電気化学素子用電極の製造方法を用いて製造することができる。
　本発明の電極の製造方法は、上述した本発明のスラリー組成物を集電体上に塗布する工程（塗布工程）と、集電体上に塗布されたスラリー組成物を乾燥して、集電体上にプレス前電極合材層を形成する工程（乾燥工程）と、プレス前電極合材層を、５００ｋＮ／ｃｍ以上３０００ｋＮ／ｃｍ以下の線圧でロールプレスして、プレス後電極合材層を得る工程（プレス工程）とを備える。 (Method of manufacturing electrode for electrochemical device)
The electrode for an electrochemical device of the present invention described above can be produced, for example, using the method for producing an electrode for an electrochemical device of the present invention.
The method for producing an electrode of the present invention comprises the steps of applying the above-described slurry composition of the present invention onto a current collector (coating step), and drying the slurry composition applied on the current collector. A step (drying step) of forming a pre-press electrode mixture layer on the body and roll pressing of the pre-press electrode mixture layer at a linear pressure of 500 kN / cm or more and 3000 kN / cm or less are performed. And a step of obtaining (pressing step).
＜塗布工程＞
　上記スラリー組成物を集電体上に塗布する方法としては、特に限定されず公知の方法を用いることができる。具体的には、塗布方法としては、ドクターブレード法、ディップ法、リバースロール法、ダイレクトロール法、グラビア法、エクストルージョン法、ハケ塗り法などを用いることができる。この際、スラリー組成物を集電体の片面だけに塗布してもよいし、両面に塗布してもよい。塗布後乾燥前の集電体上のスラリー膜の厚みは、所望の電極合材層の厚みに応じて適宜に設定しうる。 <Coating process>
The method for applying the slurry composition onto the current collector is not particularly limited, and any known method can be used. Specifically, as a coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brushing method, or the like can be used. At this time, the slurry composition may be applied to only one side of the current collector, or may be applied to both sides. The thickness of the slurry film on the current collector after application and before drying can be appropriately set according to the desired thickness of the electrode mixture layer.
　ここで、スラリー組成物を塗布する集電体としては、電気導電性を有し、かつ、電気化学的に耐久性のある材料が用いられる。具体的には、集電体としては、例えば、鉄、銅、アルミニウム、ニッケル、ステンレス鋼、チタン、タンタル、金、白金などからなる集電体を用い得る。なお、前記の材料は、１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。 Here, as a current collector to which the slurry composition is applied, a material having electrical conductivity and electrochemical durability is used. Specifically, as the current collector, for example, a current collector made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum or the like can be used. In addition, the said material may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
＜乾燥工程＞
　集電体上のスラリー組成物を乾燥する方法としては、特に限定されず公知の方法を用いることができ、例えば温風、熱風、低湿風による乾燥法、真空乾燥法、赤外線や電子線などの照射による乾燥法が挙げられる。このように集電体上のスラリー組成物を乾燥することで、集電体上にプレス前電極合材層を形成することができる。 <Drying process>
The method for drying the slurry composition on the current collector is not particularly limited, and any known method can be used, such as hot air, hot air, drying with low humidity, vacuum drying, infrared rays, electron beam, etc. The drying method by irradiation is mentioned. By thus drying the slurry composition on the current collector, the pre-press electrode mixture layer can be formed on the current collector.
＜プレス工程＞
　集電体上のプレス前電極合材層をロールプレスする際の線圧は、５００ｋＮ／ｃｍ以上３０００ｋＮ／ｃｍ以下であることが必要であり、１０００ｋＮ／ｃｍ以上であることが好ましく、２５００ｋＮ／ｃｍ以下であることが好ましい。集電体上のプレス前電極合材層は、本発明のスラリー組成物から形成されているため、５００ｋＮ／ｃｍ以上の線圧であれば、容易に圧縮されて高密度のプレス後電極合材層を得ることができる。また、線圧が３０００ｋＮ／ｃｍ以下であれば、プレスにより電極活物質が過度に破壊されることもない。
　なお、ロールプレスする際のロール温度は、通常２５℃以上１５０℃以下である。また、ロールプレスする際の、プレス前電極合材層と集電体の積層体の搬送速度は、通常５ｍ／分以上１００ｍ／分以下である。そして、ロールプレスの回数は、複数回であってもよいが、通常１回である。 <Pressing process>
The linear pressure at the time of roll-pressing the pre-press electrode mixture layer on the current collector needs to be 500 kN / cm or more and 3000 kN / cm or less, preferably 1000 kN / cm or more, 2500 kN / cm It is preferable that it is the following. Since the pre-press electrode mixture layer on the current collector is formed of the slurry composition of the present invention, a high-density post-press electrode mixture can be easily compressed if the linear pressure is 500 kN / cm or more. You can get a layer. In addition, when the linear pressure is 3000 kN / cm or less, the electrode active material is not excessively destroyed by the press.
In addition, the roll temperature at the time of roll-pressing is 25 degreeC or more and 150 degrees C or less normally. Moreover, the conveyance speed of the laminated body of the electrode compound material layer before a press, and a collector at the time of roll-pressing is 5 m / min or more and 100 m / min or less normally. And although the number of times of roll press may be two or more, it is usually one.
（電気化学素子）
　本発明の電気化学素子は、特に限定されることなく、リチウムイオン二次電池や電気二重層キャパシタであり、好ましくはリチウムイオン二次電池である。そして、本発明の電気化学素子は、本発明の電気化学素子用電極を備えるため、高容量であると共に、優れたサイクル特性を有する。 (Electrochemical device)
The electrochemical device of the present invention is not particularly limited, and is a lithium ion secondary battery or an electric double layer capacitor, preferably a lithium ion secondary battery. And since the electrochemical device of the present invention is provided with the electrode for an electrochemical device of the present invention, it has a high capacity and excellent cycle characteristics.
　ここで、以下では、一例として電気化学素子がリチウムイオン二次電池である場合について説明するが、本発明は下記の一例に限定されるものではない。本発明の電気化学素子としてのリチウムイオン二次電池は、通常、電極（正極および負極）、電解液、並びにセパレータを備え、正極および負極の少なくとも一方に本発明の電気化学素子用電極を使用する。 Here, although the case where an electrochemical element is a lithium ion secondary battery is demonstrated as an example below, this invention is not limited to the following example. The lithium ion secondary battery as the electrochemical device of the present invention generally comprises an electrode (positive electrode and negative electrode), an electrolytic solution, and a separator, and uses the electrode of the present invention for at least one of the positive electrode and the negative electrode. .
＜電極＞
　ここで、本発明の電気化学素子としてのリチウムイオン二次電池に使用し得る、上述した電気化学素子用電極以外の電極としては、特に限定されることなく、既知の電極を用いることができる。具体的には、上述した電気化学素子用電極以外の電極としては、既知の製造方法を用いて集電体上に電極合材層を形成してなる電極を用いることができる。 <Electrode>
Here, as an electrode other than the electrode for an electrochemical device described above which can be used for a lithium ion secondary battery as an electrochemical device of the present invention, known electrodes can be used without particular limitation. Specifically, as an electrode other than the electrode for an electrochemical element described above, an electrode formed by forming an electrode mixture layer on a current collector using a known manufacturing method can be used.
＜電解液＞
　電解液としては、通常、有機溶媒に支持電解質を溶解した有機電解液が用いられる。リチウムイオン二次電池の支持電解質としては、例えば、リチウム塩が用いられる。リチウム塩としては、例えば、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＳｂＦ６、ＬｉＡｌＣｌ４、ＬｉＣｌＯ４、ＣＦ３ＳＯ３Ｌｉ、Ｃ４Ｆ９ＳＯ３Ｌｉ、ＣＦ３ＣＯＯＬｉ、（ＣＦ３ＣＯ）２ＮＬｉ、（ＣＦ３ＳＯ２）２ＮＬｉ、（Ｃ２Ｆ５ＳＯ２）ＮＬｉなどが挙げられる。なかでも、溶媒に溶けやすく高い解離度を示すので、ＬｉＰＦ６、ＬｉＣｌＯ４、ＣＦ３ＳＯ３Ｌｉが好ましく、ＬｉＰＦ６が特に好ましい。なお、電解質は１種類を単独で用いてもよく、２種類以上を任意の比率で組み合わせて用いてもよい。通常は、解離度の高い支持電解質を用いるほどリチウムイオン伝導度が高くなる傾向があるので、支持電解質の種類によりリチウムイオン伝導度を調節することができる。 <Electrolyte solution>
As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. As a supporting electrolyte of a lithium ion secondary battery, for example, a lithium salt is used. Examples of lithium salts include LiPF 6 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiSbF 6 , LiAlCl 4 , LiClO 4 , CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi , (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) NLi, and the like. Among them, LiPF 6 , LiClO 4 , and CF 3 SO 3 Li are preferable, and LiPF 6 is particularly preferable because they are easily dissolved in a solvent and exhibit a high degree of dissociation. In addition, an electrolyte may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Usually, the lithium ion conductivity tends to be higher as the supporting electrolyte having a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of the supporting electrolyte.
　電解液に使用する有機溶媒としては、支持電解質を溶解できるものであれば特に限定されないが、例えば、ジメチルカーボネート（ＤＭＣ）、エチレンカーボネート（ＥＣ）、ジエチルカーボネート（ＤＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、エチルメチルカーボネート（ＥＭＣ）等のカーボネート類；γ－ブチロラクトン、ギ酸メチル等のエステル類；１，２－ジメトキシエタン、テトラヒドロフラン等のエーテル類；スルホラン、ジメチルスルホキシド等の含硫黄化合物類；などが好適に用いられる。またこれらの溶媒の混合液を用いてもよい。中でも、誘電率が高く、安定な電位領域が広いのでカーボネート類を用いることが好ましく、エチレンカーボネートとエチルメチルカーボネートとの混合物を用いることが更に好ましい。
　また、電解液には、既知の添加剤、例えば、ビニレンカーボネート（ＶＣ）、フルオロエチレンカーボネート（ＦＥＣ）やエチルメチルスルホンなどを添加してもよい。 The organic solvent used for the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte, and examples thereof include dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), Carbonates such as butylene carbonate (BC) and ethyl methyl carbonate (EMC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide Etc. are preferably used. Also, a mixture of these solvents may be used. Among them, it is preferable to use carbonates because the dielectric constant is high and the stable potential region is wide, and it is more preferable to use a mixture of ethylene carbonate and ethyl methyl carbonate.
In addition, known additives such as vinylene carbonate (VC), fluoroethylene carbonate (FEC) and ethyl methyl sulfone may be added to the electrolytic solution.
＜セパレータ＞
　セパレータとしては、特に限定されることなく、例えば特開２０１２－２０４３０３号公報に記載のものを用いることができる。これらの中でも、セパレータ全体の膜厚を薄くすることができ、これにより、リチウムイオン二次電池内の電極活物質の比率を高くして体積あたりの容量を高くすることができるという点より、ポリオレフィン系（ポリエチレン、ポリプロピレン、ポリブテン、ポリ塩化ビニル）の樹脂からなる微多孔膜が好ましい。 <Separator>
The separator is not particularly limited and, for example, those described in JP-A-2012-204303 can be used. Among these, it is possible to reduce the film thickness of the entire separator, thereby increasing the ratio of the electrode active material in the lithium ion secondary battery to increase the capacity per volume, and it is possible to use polyolefin. A microporous membrane made of a resin of a system (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred.
＜リチウムイオン二次電池の製造方法＞
　本発明の電気化学素子としてのリチウムイオン二次電池は、例えば、正極と、負極とを、セパレータを介して重ね合わせ、これを必要に応じて電池形状に応じて巻く、折るなどして電池容器に入れ、電池容器に電解液を注入して封口することにより製造することができる。リチウムイオン二次電池の内部の圧力上昇、過充放電等の発生を防止するために、必要に応じて、ヒューズ、ＰＴＣ素子等の過電流防止素子、エキスパンドメタル、リード板などを設けてもよい。リチウムイオン二次電池の形状は、例えば、コイン型、ボタン型、シート型、円筒型、角形、扁平型など、何れであってもよい。 <Method of manufacturing lithium ion secondary battery>
In the lithium ion secondary battery as the electrochemical element of the present invention, for example, the positive electrode and the negative electrode are superimposed via a separator, and this is wound or folded according to the battery shape as needed, and the battery container is , And the electrolyte container is injected into the battery container and sealed. A fuse, an over current protection element such as a PTC element, an expanded metal, a lead plate, etc. may be provided if necessary to prevent the pressure rise inside the lithium ion secondary battery and the occurrence of overcharge and discharge and the like. . The shape of the lithium ion secondary battery may be, for example, a coin, a button, a sheet, a cylinder, a square, or a flat.
　以下、本発明について実施例に基づき具体的に説明するが、本発明はこれら実施例に限定されるものではない。なお、以下の説明において、量を表す「％」及び「部」は、特に断らない限り、質量基準である。
　実施例および比較例において、重合体の電解液膨潤度、正極のピール強度、プレス前正極合材層の密度（塗布密度）、プレス後正極合材層の密度（プレス密度）、および、リチウムイオン二次電池のサイクル特性は、下記の方法で評価した。評価結果は、何れも表１に示す。 EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the following description, “%” and “parts” representing amounts are based on mass unless otherwise specified.
In Examples and Comparative Examples, the electrolyte swelling degree of the polymer, the peel strength of the positive electrode, the density (application density) of the positive electrode mixture layer before pressing, the density (press density) of the positive electrode mixture layer after pressing, and lithium ion The cycle characteristics of the secondary battery were evaluated by the following method. The evaluation results are all shown in Table 1.
＜重合体の電解液膨潤度＞
　正極用バインダー組成物（重合体のＮＭＰ溶液）を、ポリテトラフルオロエチレン製シート上に塗布し、温度８０～１２０℃の環境下で０．５～３時間乾燥させて、厚み５００μｍ±５０μｍのキャストフィルムを得た。このキャストフィルムを１ｃｍ×１ｃｍの正方形状に切り出して試験片を得て、当該試験片の質量（浸漬前質量Ａ）を測定した。その後、試験片を温度６０℃の電解液に７２時間浸漬した。なお、電解液は、ＥＣ：ＥＭＣ＝３：７（重量基準）の混合物に、ＦＥＣを濃度５質量％となるよう添加し、次いで、ＦＥＣ添加後の混合物にＬｉＰＦ６を濃度１．０Ｍとなるよう溶解し、そして、ＬｉＰＦ６溶解後の混合物に、ビニレンカーボネートを濃度２質量％となるように添加することで調製した。浸漬後の試験片を引き上げ、表面の電解液をタオルペーパーで拭き取った後、試験片の質量（浸漬後質量Ｂ）を測定した。
　そして、以下の計算式を用いて電解液膨潤度（％）を算出した。電解液膨潤度の値が低い重合体ほど、電解液中で結着性を保持し易く、電気化学素子に優れた特性（特にはサイクル特性）を発揮させ得る。
　電解液膨潤度（％）＝浸漬後質量Ｂ／浸漬前質量Ａ×１００
＜正極のピール強度＞
　正極を、幅１．０ｃｍ×長さ１０ｃｍの長方形状に切り出して試験片を得て、この試験片を、正極合材層を上にして水平な台上に固定した。そして、試験片の正極合材層表面にセロハンテープを貼り付けた後、試験片の一端からセロハンテープを５０ｍｍ／分の速度で１８０°方向に引き剥がしたときの応力を測定した。この際、セロハンテープとしてはＪＩＳ　Ｚ１５２２に規定されるものを用いた。測定を１０回行い、得られた値の平均値をピール強度（Ｎ／ｍ）とし、以下の基準で評価した。ピール強度が大きいほど、正極合材層が集電体に強固に密着していることを示す。
　Ａ：ピール強度が７０Ｎ／ｍ以上
　Ｂ：ピール強度が５０Ｎ／ｍ以上７０Ｎ／ｍ未満
　Ｃ：ピール強度が３０Ｎ／ｍ以上５０Ｎ／ｍ未満
　Ｄ：ピール強度が１０Ｎ／ｍ以上３０Ｎ／ｍ未満
　Ｅ：ピール強度が１０Ｎ／ｍ未満
＜プレス前正極合材層の密度（塗布密度）＞
　正極原反のプレス前正極合材層の厚み（ｃｍ）と塗布量（ｇ／ｃｍ２）から、以下の計算式を用いて塗布密度（ｇ／ｃｍ３）を算出した。なお、プレス前正極合材層の厚みはマイクロメーターにより測定した。塗布密度が大きいほど（即ち、プレス前正極合材層の密度が大きいほど）、ロールプレスによって高密度の正極合材層を容易に形成可能であることを示す。
　塗布密度（ｇ／ｃｍ３）＝塗布量（ｇ／ｃｍ２）／厚み（ｃｍ）
　Ａ：塗布密度が２．５ｇ／ｃｍ３以上
　Ｂ：塗布密度が２．４ｇ／ｃｍ３以上２．５ｇ／ｃｍ３未満
　Ｃ：塗布密度が２．３ｇ／ｃｍ３以上２．４ｇ／ｃｍ３未満
　Ｄ：塗布密度が２．３ｇ／ｃｍ３未満
＜プレス後正極の密度（プレス密度）＞
　正極原反を直径１．２ｃｍの円状に打ち抜いて試験片とした。この試験片を、平板の上に載置し、９ＭＰａの圧力でプレスした（プレス試験）。そして、プレス後正極合材層の厚み（ｃｍ）と重量（ｇ）を求め、電極合材層の密度を算出した。なお、プレス後正極合材層の厚みはマイクロメーターにより測定した。また、プレス後正極合材層の重量は、プレス後の試験片の重量から集電体の重量を差し引くことで算出した。このプレス試験を１０回行い、得られた値の平均値をプレス密度（ｇ／ｃｍ３）とし、以下の基準で評価した。プレス密度が大きいほど、プレス前正極合材層が圧縮性に優れ、ロールプレスによって高密度の正極合材層を容易に形成可能であることを示す。
　Ａ：プレス密度が３．８ｇ／ｃｍ３以上
　Ｂ：プレス密度が３．７ｇ／ｃｍ３以上３．８ｇ／ｃｍ３未満
　Ｃ：プレス密度が３．６ｇ／ｃｍ３以上３．７ｇ／ｃｍ３未満
　Ｄ：プレス密度が３．５ｇ／ｃｍ３以上３．６ｇ／ｃｍ３未満
　Ｅ：プレス密度が３．５ｇ／ｃｍ３未満
＜リチウムイオン二次電池のサイクル特性＞
　得られたリチウムイオン二次電池を、充電深度（ＳＯＣ；State of Charge）１０％、６０℃で１０時間エージングした。エージング後、０．２Ｃで電圧が４．２Ｖになるまで充電し、０．２Ｃで電圧が３．０Ｖになるまで放電する操作を３回繰り返した。その後、このリチウムイオン二次電池について、４５℃環境下、１Ｃで電圧が４．２Ｖになるまで充電し、１Ｃで電圧が３．０Ｖになるまで放電する操作を１００回繰り返した。そして、１サイクル終了時の放電容量に対する１００サイクル終了時の放電容量の割合を容量維持率（％）（＝｛（１００サイクル終了時の放電容量）／（１サイクル終了時の放電容量）｝×１００）とし、以下の基準で評価した。容量維持率が大きいほど、サイクル特性に優れていることを示す。
　Ａ：容量維持率が８４％以上
　Ｂ：容量維持率が８２％以上８４％未満
　Ｃ：容量維持率が８０％以上８２％未満
　Ｄ：容量維持率が７７％以上８０％未満
　Ｅ：容量維持率が７７％未満 <Electrolyte Swelling Degree of Polymer>
The binder composition for the positive electrode (polymer NMP solution) is applied onto a polytetrafluoroethylene sheet, dried for 0.5 to 3 hours in an environment at a temperature of 80 to 120 ° C., and cast to a thickness of 500 μm ± 50 μm. I got a film. The cast film was cut into a square of 1 cm × 1 cm to obtain a test piece, and the mass of the test piece (mass before immersion A) was measured. Thereafter, the test piece was immersed in an electrolytic solution at a temperature of 60 ° C. for 72 hours. The electrolytic solution is added to a mixture of EC: EMC = 3: 7 (by weight) so that the concentration becomes 5% by mass, and then the mixture after the addition of FEC has a concentration of 1.0 M of LiPF 6 The mixture was dissolved and prepared by adding vinylene carbonate to a concentration of 2% by mass to the mixture after dissolution of LiPF 6 . The test piece after immersion was pulled up, the surface electrolyte solution was wiped off with a towel paper, and then the mass of the test piece (mass after immersion B) was measured.
And swelling degree (%) of electrolyte solution was computed using the following formula. As the polymer having a lower value of the degree of swelling of the electrolyte, the binding property can be more easily maintained in the electrolyte, and the electrochemical device can exhibit excellent characteristics (particularly, cycle characteristics).
Electrolyte swelling degree (%) = mass after immersion B / mass before immersion A × 100
<Peel strength of positive electrode>
The positive electrode was cut out in a rectangular shape of width 1.0 cm × length 10 cm to obtain a test piece, and this test piece was fixed on a horizontal stand with the positive electrode composite material layer facing up. Then, a cellophane tape was attached to the surface of the positive electrode mixture layer of the test piece, and then the stress when peeling off the cellophane tape from one end of the test piece at a speed of 50 mm / min in a 180 ° direction was measured. Under the present circumstances, as a cellophane tape, what was prescribed | regulated to JISZ1522 was used. The measurement was carried out 10 times, and the average value of the obtained values was taken as peel strength (N / m), and evaluated according to the following criteria. The higher the peel strength, the tighter the positive electrode mixture layer is in close contact with the current collector.
A: Peel strength is 70 N / m or more B: Peel strength is 50 N / m to 70 N / m C: Peel strength is 30 N / m to 50 N / m D: Peel strength is 10 N / m to 30 N / m E: Peel strength less than 10 N / m <density of pre-press positive electrode mixture layer (coating density)>
The coating density (g / cm 3 ) was calculated from the thickness (cm) and the coating amount (g / cm 2 ) of the pre-press positive electrode mixture layer of the positive electrode raw fabric using the following formula. The thickness of the positive electrode mixture layer before pressing was measured by a micrometer. As the application density is higher (that is, the density of the pre-pressing positive electrode mixture layer is higher), it is shown that the roll pressing can form a high-density positive electrode mixture layer more easily.
Coating density (g / cm 3 ) = coating amount (g / cm 2 ) / thickness (cm)
A: Coating density is 2.5 g / cm 3 or more B: Coating density is 2.4 g / cm 3 to 2.5 g / cm 3 C: Coating density is 2.3 g / cm 3 to 2.4 g / cm 3 D: Coating density is less than 2.3 g / cm 3 <density of positive electrode after pressing (press density)>
The positive electrode material sheet was punched into a circle having a diameter of 1.2 cm to prepare a test piece. The test piece was placed on a flat plate and pressed at a pressure of 9 MPa (press test). Then, the thickness (cm) and the weight (g) of the positive electrode mixture layer after pressing were determined, and the density of the electrode mixture layer was calculated. The thickness of the positive electrode mixture layer after pressing was measured by a micrometer. In addition, the weight of the positive electrode mixture layer after pressing was calculated by subtracting the weight of the current collector from the weight of the test piece after pressing. This press test was performed 10 times, and the average value of the obtained values was used as a press density (g / cm 3 ), and evaluated based on the following criteria. The larger the press density, the better the compressibility of the pre-press positive electrode mixture layer, and it is shown that a high-density positive electrode mixture layer can be easily formed by roll pressing.
A: press density is 3.8 g / cm 3 or more B: press density is 3.7 g / cm 3 or more 3.8 g / cm 3 less C: less than the press density of 3.6 g / cm 3 or more 3.7 g / cm 3 D: Press density is 3.5 g / cm 3 or more and less than 3.6 g / cm 3 E: Press density is less than 3.5 g / cm 3 <cycle characteristics of lithium ion secondary battery>
The obtained lithium ion secondary battery was aged at 60 ° C. for 10 hours at a charge depth (SOC; State of Charge) of 10%. After aging, charging was performed at 0.2 C until the voltage reached 4.2 V, and an operation of discharging at 0.2 C until the voltage reached 3.0 V was repeated three times. Thereafter, the operation of charging this lithium ion secondary battery to a voltage of 4.2 V at 1 C in a 45 ° C. environment and discharging the voltage to 3.0 V at 1 C was repeated 100 times. And the ratio of the discharge capacity at the end of 100 cycles to the discharge capacity at the end of one cycle is the capacity retention rate (%) (= {(discharge capacity at the end of 100 cycles) / (discharge capacity at the end of 1 cycle)} 100) and evaluated according to the following criteria. The larger the capacity retention rate, the better the cycle characteristics.
A: Capacity retention rate is 84% or more B: Capacity retention rate is 82% or more and less than 84% C: Capacity retention rate is 80% or more and less than 82% D: Capacity retention rate is 77% or more and less than 80% E: Capacity retention rate Less than 77%
（実施例１）
＜重合体および正極用バインダー組成物の調製＞
　反応器に、脂肪族共役ジエン単量体としての１，３－ブタジエン１０．０部およびイソプレン２０．０部、ニトリル基含有単量体としてのアクリロニトリル７０．０部、ｔ－ドデシルメルカプタン０．４部、イオン交換水１３２部、ドデシルベンゼンスルホン酸ナトリウム３部、β－ナフタリンスルホン酸ホルマリン縮合物ナトリウム塩０．５部、過硫酸カリウム０．３部、並びに、エチレンジアミン四酢酸ナトリウム塩０．０５部を仕込み、重合温度を１５℃に保持して重合を行い、重合転化率が９４％に達するまで反応させた。その後、内容物を常温に戻し、系内を窒素雰囲気とした後、エバポレータを用いて固形分濃度が４０％となるまで濃縮して、重合体の水分散液を得た。
　この重合体の水分散液１００部にＮＭＰ３２０部を加え、次いで減圧下で水を蒸発させることで溶媒置換を行い、重合体のＮＭＰ溶液（正極用バインダー組成物）を得た。
　得られた重合体のＮＭＰ溶液１００ｇをメタノール１Ｌで凝固した後、６０℃で一晩真空乾燥し、乾燥体を得た。この乾燥体をＮＭＲ法により分析し、重合体は、アクリロニトリル単位を７０％、１，３－ブタジエン単位を１０％、イソプレン単位を２０％含んでいることを確認した。
＜正極用スラリー組成物の調製＞
　正極活物質としてのＬｉ（Ｎｉ０．５Ｃｏ０．２Ｍｎ０．３）Ｏ２（平均粒子径：１０μｍ）９６部と、導電材としてのアセチレンブラック（電気化学工業社製、製品名「ＨＳ－１００」）２．０部と、上述の正極用バインダー組成物（固形分濃度：８．０％）を固形分換算で２．０部と、追加の溶媒として適量のＮＭＰとをプラネタリーミキサーに加え、当該ミキサーで混合することにより、正極用スラリー組成物を調製した。
＜正極の作製＞
　集電体として、厚さ２０μｍのアルミ箔を準備した。上述のようにして調製した正極用スラリー組成物を、アルミ箔の一方の面に、乾燥後の塗布量が２２ｍｇ／ｃｍ２程度になるように塗布した。そして、アルミ箔上の塗膜を８０℃で２０分、１２０℃で２０分間乾燥後、１５０℃で２時間加熱処理して、プレス前負極合材層と集電体からなる正極原反を得た。この正極原反を、２０００ｋＮ／ｃｍの線圧でロールプレスして、密度が３．７ｇ／ｃｍ３の正極合材層を集電体の片面に備える正極を作製した。
＜負極の作製＞
　負極活物質としての球状人造黒鉛（体積平均粒子径：１２μｍ）９０部とＳｉＯｘ（体積平均粒子径：１０μｍ）１０部との混合物、結着材としてのスチレンブタジエンゴム（個数平均粒子径：１８０ｎｍ、ガラス転移温度：１０℃）１部、増粘剤としてカルボキシメチルセルロース１部、および適量の水をプラネタリーミキサーにて攪拌し、負極用スラリー組成物を調製した。
　次に、集電体として、厚さ１５μｍの銅箔を準備した。上述のようにして調製した負極用スラリー組成物を、銅箔の一方の面に、乾燥後の塗布量が１２ｍｇ／ｃｍ２になるように塗布した。そして、銅箔上の塗膜を５０℃で２０分、１１０℃で２０分間乾燥後、１５０℃で２時間加熱処理して、負極原反を得た。この負極原反をロールプレスで圧延し、密度が１．８ｇ／ｃｍ３の負極合材層を集電体の片面に備える負極を作製した。
＜リチウムイオン二次電池の作製＞
　作製した正極と負極とを、厚さ２０μｍのセパレータ（ポリプロピレン製微多孔膜）を介在させて、直径２０ｍｍの芯を用いて捲回し、捲回体を得た。なお、正極および負極は、正極合材層と負極合材層がセパレータを介して向き合うように配置した。そして、得られた捲回体を、１０ｍｍ／秒の速度で厚さ４．５ｍｍになるまで一方向から圧縮した。なお、圧縮後の捲回体は平面視楕円形をしており、その長径と短径との比（長径／短径）は７．７であった。
　また別途、ＥＣ：ＥＭＣ＝３：７（重量基準）の混合物に、ＦＥＣを濃度５質量％となるよう添加した。次いで、ＦＥＣ添加後の混合物にＬｉＰＦ６を濃度１．０Ｍとなるよう溶解した。そして、ＬｉＰＦ６溶解後の混合物に、ビニレンカーボネートを濃度２質量％となるように添加することで、電解液を調製した。
　そして、圧縮後の捲回体をアルミ製ラミネートケース内に３．２ｇの電解液とともに収容した。そして、負極の所定の箇所にリード線を接続し、正極の所定の箇所にリード線を接続したのち、ケースの開口部を熱で封口し、リチウムイオン二次電池とした。このリチウムイオン二次電池は、幅３５ｍｍ、高さ４８ｍｍ、厚さ５ｍｍのパウチ形であり、電池の公称容量は７２０ｍＡｈであった。 Example 1
<Preparation of Polymer and Binder Composition for Positive Electrode>
In the reactor, 10.0 parts of 1,3-butadiene as aliphatic conjugated diene monomer and 20.0 parts of isoprene, 70.0 parts of acrylonitrile as nitrile group-containing monomer, t-dodecyl mercaptan 0.4 Parts, 132 parts of ion exchange water, 3 parts of sodium dodecylbenzene sulfonate, 0.5 parts of sodium salt of β-naphthalenesulfonic acid formalin condensate, 0.3 parts of potassium persulfate, and 0.05 parts of ethylenediaminetetraacetic acid sodium salt The polymerization was carried out while maintaining the polymerization temperature at 15.degree. C., and the reaction was allowed to proceed until the polymerization conversion reached 94%. Thereafter, the contents were returned to normal temperature, and the system was changed to a nitrogen atmosphere, and then concentrated using an evaporator until the solid content concentration became 40%, to obtain an aqueous dispersion of a polymer.
Then, 320 parts of NMP was added to 100 parts of the aqueous dispersion of this polymer, and then water was evaporated under reduced pressure to carry out solvent substitution to obtain an NMP solution of the polymer (binder composition for positive electrode).
After 100 g of an NMP solution of the obtained polymer was coagulated with 1 L of methanol, it was vacuum dried overnight at 60 ° C. to obtain a dried product. The dried product was analyzed by NMR method, and it was confirmed that the polymer contained 70% of acrylonitrile units, 10% of 1,3-butadiene units, and 20% of isoprene units.
<Preparation of Slurry Composition for Positive Electrode>
96 parts of Li (Ni 0.5 Co 0.2 Mn 0.3 ) O 2 (average particle diameter: 10 μm) as a positive electrode active material and acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., product name “HS Planetary mixer with 2.0 parts of “-100”), 2.0 parts of the above binder composition for positive electrode (solid content concentration: 8.0%) in terms of solid content, and an appropriate amount of NMP as an additional solvent In addition, the slurry composition for positive electrodes was prepared by mixing with the said mixer.
<Fabrication of positive electrode>
A 20 μm thick aluminum foil was prepared as a current collector. The positive electrode slurry composition prepared as described above was applied to one surface of an aluminum foil so that the applied amount after drying was about 22 mg / cm 2 . Then, the coated film on aluminum foil is dried at 80 ° C. for 20 minutes and 120 ° C. for 20 minutes, and then heat treated at 150 ° C. for 2 hours to obtain a positive electrode original fabric comprising a pre-pressing negative electrode mixture layer and a current collector. The This positive electrode material sheet was roll pressed at a linear pressure of 2000 kN / cm to produce a positive electrode including a positive electrode mixture layer having a density of 3.7 g / cm 3 on one side of the current collector.
<Fabrication of negative electrode>
Mixture of 90 parts of spherical artificial graphite (volume average particle diameter: 12 μm) and 10 parts of SiO x (volume average particle diameter: 10 μm) as negative electrode active material, styrene butadiene rubber as binder (number average particle diameter: 180 nm Glass transition temperature: 10 ° C.) 1 part, carboxymethyl cellulose 1 part as a thickener, and an appropriate amount of water were stirred by a planetary mixer to prepare a slurry composition for a negative electrode.
Next, a copper foil with a thickness of 15 μm was prepared as a current collector. The negative electrode slurry composition prepared as described above was applied to one side of a copper foil so that the applied amount after drying was 12 mg / cm 2 . Then, the coated film on the copper foil was dried at 50 ° C. for 20 minutes and 110 ° C. for 20 minutes, and then heat-treated at 150 ° C. for 2 hours to obtain a negative electrode original fabric. The negative electrode material sheet was rolled by a roll press to prepare a negative electrode including a negative electrode mixture layer having a density of 1.8 g / cm 3 on one side of the current collector.
<Fabrication of lithium ion secondary battery>
The produced positive electrode and negative electrode were wound with a 20-μm-thick separator (microporous polypropylene film) interposed therebetween, using a core having a diameter of 20 mm, to obtain a wound body. The positive electrode and the negative electrode were disposed such that the positive electrode mixture layer and the negative electrode mixture layer faced each other with the separator interposed therebetween. And the obtained winding body was compressed from one direction to a thickness of 4.5 mm at a speed of 10 mm / sec. In addition, the winding body after compression was carrying out the planar view ellipse, and ratio (long diameter / short diameter) of the major axis and minor axis was 7.7.
Separately, FEC was added to a mixture of EC: EMC = 3: 7 (by weight) to a concentration of 5% by mass. Next, LiPF 6 was dissolved in the mixture after the addition of FEC to a concentration of 1.0 M. Then, an electrolytic solution was prepared by adding vinylene carbonate to the mixture after the dissolution of LiPF 6 so as to have a concentration of 2% by mass.
And the winding body after compression was accommodated in the aluminum lamination case with 3.2 g of electrolyte solution. Then, a lead wire was connected to a predetermined portion of the negative electrode, and a lead wire was connected to a predetermined portion of the positive electrode, and then the opening of the case was sealed with heat to obtain a lithium ion secondary battery. The lithium ion secondary battery was a pouch having a width of 35 mm, a height of 48 mm, and a thickness of 5 mm, and the nominal capacity of the battery was 720 mAh.
（実施例２～７）
　重合体の調製時に表１に記載の単量体組成を採用した以外は、実施例１と同様にして、重合体のＮＭＰ溶液（正極用バインダー組成物）、正極用スラリー組成物、正極、負極、およびリチウムイオン二次電池を作製した。なお、実施例１と同様にしてＮＭＲ法による分析を行い、重合体中に占める、ある単量体単位の割合が、その重合体の重合に用いた全単量体に占める当該ある単量体の比率（仕込み比）と一致することを確認した。 (Examples 2 to 7)
An NMP solution of a polymer (binder composition for positive electrode), slurry composition for positive electrode, positive electrode, negative electrode in the same manner as Example 1 except that the monomer composition described in Table 1 was adopted at the time of preparation of the polymer. , And a lithium ion secondary battery. In addition, the analysis by NMR method is performed in the same manner as in Example 1, and the ratio of a certain monomer unit in the polymer is the certain monomer in the whole monomers used for the polymerization of the polymer. It confirmed that it matched with the ratio (feed ratio) of.
（比較例１～２）
　重合体の調製時に表１に記載の単量体組成を採用した以外は、実施例１と同様にして、重合体のＮＭＰ溶液（正極用バインダー組成物）、正極用スラリー組成物、正極、負極、およびリチウムイオン二次電池を作製した。なお、実施例１と同様にしてＮＭＲ法による分析を行い、重合体中に占める、ある単量体単位の割合が、その重合体の重合に用いた全単量体に占める当該ある単量体の比率（仕込み比）と一致することを確認した。 (Comparative Examples 1 and 2)
An NMP solution of a polymer (binder composition for positive electrode), slurry composition for positive electrode, positive electrode, negative electrode in the same manner as Example 1 except that the monomer composition described in Table 1 was adopted at the time of preparation of the polymer. , And a lithium ion secondary battery. In addition, the analysis by NMR method is performed in the same manner as in Example 1, and the ratio of a certain monomer unit in the polymer is the certain monomer in the whole monomers used for the polymerization of the polymer. It confirmed that it matched with the ratio (feed ratio) of.
（比較例３）
　重合体の調製時に表１に記載の単量体組成を採用した以外は、実施例１と同様にして重合体の水分散液を調製した。そして実施例１と同様にしてＮＭＰへの溶媒置換を行ったが、重合体がＮＭＰに溶解しなかった。このような正極用バインダー組成物を用いても、優れた性能を発揮するリチウムイオン二次電池が得られないことは明らかであったため、正極、負極、およびリチウムイオン二次電池は製造しなかった。なお、重合体の電解液膨潤度の項目については評価を行った。また、実施例１と同様にしてＮＭＲ法による分析を行い、重合体中に占める、ある単量体単位の割合が、その重合体の重合に用いた全単量体に占める当該ある単量体の比率（仕込み比）と一致することを確認した。
  (Comparative example 3)
An aqueous dispersion of a polymer was prepared in the same manner as in Example 1 except that the monomer composition described in Table 1 was adopted at the preparation of the polymer. And although solvent substitution to NMP was performed like Example 1, a polymer did not dissolve in NMP. Even when such a binder composition for a positive electrode was used, it was clear that a lithium ion secondary battery exhibiting excellent performance could not be obtained, so no positive electrode, negative electrode and lithium ion secondary battery were produced. . The items of the degree of swelling of the electrolyte of the polymer were evaluated. Further, analysis by NMR method is performed in the same manner as in Example 1, and the ratio of a certain monomer unit in the polymer is the corresponding monomer in all the monomers used for the polymerization of the polymer. It confirmed that it matched with the ratio (feed ratio) of.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１より、ニトリル基含有単量体単位と、２種の脂肪族共役ジエン単量体単位とを含む重合体を含有するバインダー組成物を用いた実施例１～７では、塗布密度を高めつつ、電極合材層を十分に高密度化し得ることがわかる。また、実施例１～７では、電極合材層を集電体に強固に密着させて、リチウムイオン二次電池に、十分に優れたサイクル特性を発揮させ得ることが分かる。
　一方、ニトリル基含有単量体単位を含むが、脂肪族共役ジエン単量体単位として１，３－ブタジエン単位のみを含む重合体を含有するバインダー組成物を用いた比較例１では、電極合材層の高密度化が困難であることが分かる。
　また、ニトリル基含有単量体単位を含むが、脂肪族共役ジエン単量体単位としてイソプレン単位のみを含む重合体を含有するバインダー組成物を用いた比較例２では、電極合材層の高密度化が困難であることが分かる。
　そして、２種の脂肪族共役ジエン単量体単位を含むが、ニトリル基含有単量体単位を含まない重合体を含有するバインダー組成物を用いた比較例３では、上述した通り、重合体がＮＭＰに溶解しなかったため、正極、負極、およびリチウムイオン二次電池は製造しなかった。 From Table 1, in Examples 1 to 7 using a binder composition containing a polymer containing a nitrile group-containing monomer unit and two aliphatic conjugated diene monomer units, the coating density is increased. It can be seen that the electrode mixture layer can be sufficiently densified. Further, in Examples 1 to 7, it is understood that the electrode mixture layer can be closely adhered to the current collector, and the lithium ion secondary battery can exhibit sufficiently excellent cycle characteristics.
On the other hand, in Comparative Example 1 using a binder composition containing a nitrile group-containing monomer unit but containing a polymer containing only a 1,3-butadiene unit as an aliphatic conjugated diene monomer unit, the electrode mixture It can be seen that it is difficult to densify the layers.
Moreover, in Comparative Example 2 using a binder composition containing a nitrile group-containing monomer unit but containing a polymer containing only an isoprene unit as an aliphatic conjugated diene monomer unit, the high density of the electrode mixture layer To be difficult to
And, in Comparative Example 3 using a binder composition containing a polymer containing two aliphatic conjugated diene monomer units but not containing a nitrile group-containing monomer unit, as described above, the polymer is The positive electrode, the negative electrode, and the lithium ion secondary battery were not manufactured because they were not dissolved in NMP.
　本発明によれば、電極合材層を容易に高密度化しつつ、当該電極合材層を集電体に強固に密着させうる電気化学素子電極用バインダー組成物および電気化学素子電極用スラリー組成物を提供することができる。
　また、本発明によれば、電気化学素子を高容量化しうり、且つ当該電気化学素子に優れたサイクル特性を発揮させうる電気化学素子用電極および当該電気化学素子用電極の製造方法を提供することができる。
　更に、本発明によれば、高容量であると共に、サイクル特性に優れる電気化学素子を提供することができる。 According to the present invention, a binder composition for an electrochemical element electrode and a slurry composition for an electrochemical element electrode capable of firmly adhering the electrode mixture layer to a current collector while easily densifying the electrode mixture layer. Can be provided.
Further, according to the present invention, it is possible to provide an electrode for an electrochemical device which can increase the capacity of the electrochemical device and can exhibit excellent cycle characteristics to the electrochemical device, and a method of manufacturing the electrode for the electrochemical device. Can.
Furthermore, according to the present invention, it is possible to provide an electrochemical device having high capacity and excellent cycle characteristics.

Claims (12)

  1. 　重合体を含有する電気化学素子電極用バインダー組成物であって、
    　前記重合体が、ニトリル基含有単量体単位と、少なくとも２種の脂肪族共役ジエン単量体単位とを含む、電気化学素子電極用バインダー組成物。     It is a binder composition for electrochemical element electrodes containing a polymer, comprising:
    A binder composition for an electrochemical element electrode, wherein the polymer comprises a nitrile group-containing monomer unit and at least two aliphatic conjugated diene monomer units.
  2. 　前記脂肪族共役ジエン単量体単位が、炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位を含む、請求項１に記載の電気化学素子電極用バインダー組成物。 The binder composition for an electrochemical element electrode according to claim 1, wherein the aliphatic conjugated diene monomer unit contains an aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms.
  3. 　前記重合体中の前記炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合が、１質量％以上５０質量％以下である、請求項２に記載の電気化学素子電極用バインダー組成物。 The binder composition for an electrochemical element according to claim 2, wherein a proportion of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms in the polymer is 1% to 50% by mass. object.
  4. 　前記脂肪族共役ジエン単量体単位が、１，３－ブタジエン単位を含む、請求項１～３の何れかに記載の電気化学素子電極用バインダー組成物。 The binder composition for an electrochemical element electrode according to any one of claims 1 to 3, wherein the aliphatic conjugated diene monomer unit contains a 1,3-butadiene unit.
  5. 　前記重合体中の前記１，３－ブタジエン単位の割合が、１質量％以上５０質量％以下である、請求項４に記載の電気化学素子電極用バインダー組成物。 The binder composition for electrochemical element electrodes of Claim 4 whose ratio of the said 1, 3- butadiene unit in the said polymer is 1 mass% or more and 50 mass% or less.
  6. 　前記重合体中の前記ニトリル基含有単量体単位の割合が、２０質量％以上８５質量％以下である、請求項１～５の何れかに記載の電気化学素子電極用バインダー組成物。 The binder composition for an electrochemical element electrode according to any one of claims 1 to 5, wherein a proportion of the nitrile group-containing monomer unit in the polymer is 20% by mass or more and 85% by mass or less.
  7. 　前記脂肪族共役ジエン単量体単位が、炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位および１，３－ブタジエン単位を含み、前記重合体中の前記１，３－ブタジエン単位の割合に対する前記炭素原子数５以上１２以下の脂肪族共役ジエン単量体単位の割合の比が、０．０２以上５０以下である、請求項１～６の何れかに記載の電気化学素子電極用バインダー組成物。 The aliphatic conjugated diene monomer unit includes an aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms and a 1,3-butadiene unit, and the 1,3-butadiene unit in the polymer The electrochemical device electrode according to any one of claims 1 to 6, wherein a ratio of the ratio of the aliphatic conjugated diene monomer unit having 5 to 12 carbon atoms to the ratio is 0.02 to 50. Binder composition.
  8. 　電極活物質と、請求項１～７の何れかに記載の電気化学素子電極用バインダー組成物とを含む、電気化学素子電極用スラリー組成物。 A slurry composition for an electrochemical device electrode, comprising the electrode active material and the binder composition for an electrochemical device electrode according to any one of claims 1 to 7.
  9. 　前記電極活物質が、ニッケルを含有する電極活物質である、請求項８に記載の電気化学素子電極用スラリー組成物。 The slurry composition for electrochemical device electrodes according to claim 8, wherein the electrode active material is an electrode active material containing nickel.
  10. 　請求項８または９に記載の電気化学素子電極用スラリー組成物を用いて形成した電極合材層を備える、電気化学素子用電極。 An electrode for an electrochemical element, comprising an electrode mixture layer formed using the slurry composition for an electrochemical element according to claim 8 or 9.
  11. 　請求項１０に記載の電気化学素子用電極を備える、電気化学素子。 An electrochemical device comprising the electrode for an electrochemical device according to claim 10.
  12. 　請求項８または９に記載の電気化学素子電極用スラリー組成物を集電体上に塗布する工程と、
    　前記集電体上に塗布された前記電気化学素子電極用スラリー組成物を乾燥して、前記集電体上にプレス前電極合材層を形成する工程と、
    　前記プレス前電極合材層を、５００ｋＮ／ｃｍ以上３０００ｋＮ／ｃｍ以下の線圧でロールプレスして、プレス後電極合材層を得る工程と、を含む、
    　電気化学素子用電極の製造方法。     Applying the slurry composition for an electrochemical element electrode according to claim 8 or 9 onto a current collector;
    Drying the slurry composition for an electrochemical element electrode applied on the current collector to form a pre-press electrode mixture layer on the current collector;
    Roll pressing the pre-press electrode mixture layer at a linear pressure of 500 kN / cm or more and 3000 kN / cm or less to obtain a post-press electrode mixture layer
    The manufacturing method of the electrode for electrochemical elements.
PCT/JP2018/024204 2017-06-29 2018-06-26 Binder composition for electrochemical element electrode, slurry composition for electrochemical element electrode, electrochemical element electrode, electrochemical element, and method for manufacturing electrochemical element electrode WO2019004216A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1368780A (en) * 1970-12-31 1974-10-02 Nippon Zeon Co Terpolymers of acrylonitrile butadiene and isoprene
WO2008032699A1 (en) * 2006-09-11 2008-03-20 Zeon Corporation Electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery using the same
WO2016157842A1 (en) * 2015-03-27 2016-10-06 日本ゼオン株式会社 Binder composition for lithium-ion secondary cell positive electrode, slurry composition for lithium-ion secondary cell positive electrode, lithium-ion secondary cell positive electrode, and lithium-ion secondary cell

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1368780A (en) * 1970-12-31 1974-10-02 Nippon Zeon Co Terpolymers of acrylonitrile butadiene and isoprene
WO2008032699A1 (en) * 2006-09-11 2008-03-20 Zeon Corporation Electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery using the same
WO2016157842A1 (en) * 2015-03-27 2016-10-06 日本ゼオン株式会社 Binder composition for lithium-ion secondary cell positive electrode, slurry composition for lithium-ion secondary cell positive electrode, lithium-ion secondary cell positive electrode, and lithium-ion secondary cell

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