WO2024162376A1 - 共重合体、バインダー、電極合剤、電極、及び電池 - Google Patents

共重合体、バインダー、電極合剤、電極、及び電池 Download PDF

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WO2024162376A1
WO2024162376A1 PCT/JP2024/003006 JP2024003006W WO2024162376A1 WO 2024162376 A1 WO2024162376 A1 WO 2024162376A1 JP 2024003006 W JP2024003006 W JP 2024003006W WO 2024162376 A1 WO2024162376 A1 WO 2024162376A1
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vinylidene fluoride
copolymer
structural unit
electrode
fluoride copolymer
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French (fr)
Japanese (ja)
Inventor
幸弘 高橋
拓也 山根
勇樹 堺
マユミ 菅原
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Kureha Corp
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Kureha Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
    • C08F214/18—Monomers containing fluorine
    • C08F214/22—Vinylidene fluoride
    • C08F214/225—Vinylidene fluoride with non-fluorinated comonomers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/48—Isomerisation; Cyclisation
    • 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
    • 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 copolymer, a binder, an electrode mixture, an electrode, and a battery.
  • vinylidene fluoride polymers such as polyvinylidene fluoride are mainly used as binders (binding agents). High adhesiveness is required for the binder, as it serves the role of adhering the active material to the current collector.
  • Patent Document 1 discloses a compound comprising vinylidene fluoride and the following formula (3): It is disclosed that an electrode prepared using a binder composition containing a copolymer with a compound represented by the formula: has high peel strength.
  • the present invention was made in consideration of the above problems, and aims to provide a new vinylidene fluoride copolymer that has excellent adhesion to metal foil when an electrode is formed, a binder containing said copolymer, an electrode mixture containing said binder, an electrode using said electrode mixture, and a battery equipped with said electrode.
  • aspects of the present invention relate to the following copolymers, binders, electrode mixtures, electrodes, and batteries.
  • An electrode comprising: a current collector; and the electrode mixture layer according to [3], disposed on at least one surface of the current collector.
  • a battery comprising the electrode according to [4].
  • the present invention provides a novel vinylidene fluoride copolymer that has excellent adhesion to metal foil when an electrode is formed, a binder containing the copolymer, an electrode mixture containing the binder, an electrode using the electrode mixture, and a battery including the electrode.
  • 1 shows FT-IR spectra obtained for vinylidene fluoride copolymers A1 to A6 prepared in Examples 1 to 5 and Comparative Example 1.
  • 1 shows 19 F-NMR spectra obtained for vinylidene fluoride copolymers A1 to A6 prepared in Examples 1 to 5 and Comparative Example 1.
  • the copolymer of the present embodiment is a copolymer containing a structural unit (a1) derived from vinylidene fluoride,
  • a1 a structural unit derived from vinylidene fluoride
  • the FT-IR spectrum obtained by measuring the powder of the copolymer there are absorption peaks in the ranges of 1780 to 1800 cm ⁇ 1 and 1850 to 1870 cm ⁇ 1 , respectively.
  • the 19 F-NMR spectrum obtained by measuring a powder of the copolymer at least two peaks are present in the range of -91.0 to -89.0 ppm.
  • the copolymer of the present embodiment is subjected to IR measurement and NMR measurement, if the copolymer has peaks in the above range, this means that the copolymer contains a structural unit (a2) having a specific cyclic acid anhydride structure, which will be described later, in the main chain of the polymer.
  • an electrode formed using a binder containing the copolymer has an effect of being more excellent in adhesion to a metal foil.
  • the vinylidene fluoride copolymer (A) contains, in the main chain of the polymer, a structural unit (a1) derived from vinylidene fluoride and a structural unit (a2) having a specific cyclic acid anhydride structure.
  • the structural unit (a1) derived from vinylidene fluoride is a main structural unit of the copolymer.
  • the content of the structural unit (a1) derived from vinylidene fluoride relative to the total structural units of the copolymer is preferably 90.000 mol% or more and 99.999 mol% or less, more preferably 99.000 mol% or more and 99.900 mol% or less.
  • the structural unit (a2) having a cyclic acid anhydride structure is preferably a structural unit represented by the following formula (1).
  • R1 and R2 each represent a hydrogen atom.
  • X represents a methylene group or an ethylene group.
  • X is preferably a methylene group.
  • the content of the structural unit (a2) relative to the total structural units of the vinylidene fluoride copolymer (A) is preferably 0.001 mol% or more and 1.000 mol% or less, more preferably 0.010 mol% or more and 1.000 mol% or less, even more preferably 0.100 mol% or more and 1.000 mol% or less, and even more preferably 0.200 mol% or more and 1.000 mol% or less, from the viewpoint of excellent adhesion to the metal foil of an electrode formed using a binder containing the copolymer (A).
  • vinylidene fluoride copolymer (A) has a structural unit (a2) having a cyclic acid anhydride structure.
  • a spectrum is obtained according to the following procedures (1) to (3): (1) A vinylidene fluoride copolymer (A) is freeze-pulverized in liquid nitrogen using a freeze-pulverizer to obtain a powder. (2) The obtained powder is mixed with potassium bromide and thoroughly ground in a mortar to obtain a mixture.
  • the obtained mixture is measured in the range of 1500 cm -1 to 4000 cm -1 using a diffuse reflectance measuring device and an infrared spectrophotometer, and a spectrum is obtained in which the Kubelka-Munk transformation of absorbance is plotted on the vertical axis and the wave number on the horizontal axis.
  • the presence or absence of a peak is determined by differentiating the regions of the spectrum obtained from 1780 cm -1 to 1800 cm -1 and 1850 cm -1 to 1870 cm -1 .
  • a peak is determined to exist at a wave number where the differential value changes from a positive value to a negative value.
  • there is no wave number where the differential value changes from a positive value to a negative value it is determined that there is no peak in this region.
  • vinylidene fluoride copolymer (A) has a structural unit (a2) having a cyclic acid anhydride structure in the polymer main chain
  • 19 F-NMR measurement using a nuclear magnetic resonance apparatus.
  • the largest peak derived from the 19 F atom of vinylidene fluoride at the normal bonding site of vinylidene fluoride copolymer (A) is set at -91.6 ppm in the obtained spectrum
  • two peaks derived from the 19 F atom of the structural unit (a1) derived from vinylidene fluoride adjacent to the introduced cyclic acid anhydride structure appear at -91.0 ppm to -89.0 ppm. If this peak is observed, it can be said that the vinylidene fluoride copolymer (A) has a cyclic acid anhydride structure in the polymer main chain.
  • the main chain of vinylidene fluoride copolymer (A) may contain other structural units other than the above structural unit (a1) and the above structural unit (a2) as long as it does not impair the effect of the present invention.
  • the other structural units include, for example, the structural unit (a3) described later; vinyl fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, fluoroalkyl vinyl ether, perfluoroalkyl vinyl ether represented by perfluoromethyl vinyl ether; (meth)acrylic acid, (meth)acrylic acid ester represented by methyl (meth)acrylate, acryloyloxyethyl succinic acid, acryloyloxypropyl succinic acid, carboxyethyl acrylate, etc.
  • R1 and R2 are each a hydrogen atom
  • R3 represents a hydrogen atom, a methyl group, an ethyl group, or a butyl group
  • X represents a methylene group or an ethylene group.
  • the structural unit (a3) is a structural unit that is not cyclized to the structural unit (a2) in the embodiment of the production method of the vinylidene fluoride copolymer (A) described below. From the viewpoint that the electrode formed by using the binder containing the vinylidene fluoride copolymer (A) has excellent adhesion to the metal foil, it is preferable that the content of the structural unit (a3) is small and the content of the structural unit (a2) is large.
  • the content of the structural unit (a2) is preferably 1.0 mol% or more and 100.0 mol% or less, preferably 10.0 mol% or more and 99.0 mol% or less, more preferably 30.0 mol% or more and 99.0 mol% or less, even more preferably 50.0 mol% or more and 99.0 mol% or less, and even more preferably 70.0 mol% or more and 99.0 mol% or less.
  • the melting point of the vinylidene fluoride copolymer (A) is preferably 160° C. or higher and 180° C. or lower, more preferably 165° C. or higher and 178° C. or lower, and most preferably 165° C. or higher and 175° C. or lower.
  • the vinylidene fluoride copolymer (A) has a melting point of 160° C. or higher, it is difficult to swell with an electrolyte, and the performance of the resulting battery tends to be good.
  • the melting point is 180° C. or lower, the flexibility when the electrode is formed tends to be good.
  • the melting point of the vinylidene fluoride copolymer (A) can be determined by calorimetry using a differential scanning calorimeter (DSC). Specifically, the vinylidene fluoride copolymer (A) is heated from 30°C to 230°C at a rate of 10°C/min (first heating), cooled from 230°C to 30°C at a rate of 10°C/min (first cooling), and then heated from 30°C to 230°C at a rate of 10°C/min (second heating). Then, the melting peak is determined by DSC. In this specification, the maximum melting peak temperature observed in the second heating is defined as the melting point of the vinylidene fluoride copolymer (A).
  • the inherent viscosity of the vinylidene fluoride copolymer (A) is preferably 0.5 dL/g or more and 8.0 dL/g or less, more preferably 1.0 dL/g or more and 5.0 dL/g or less, and most preferably 1.0 dL/g or more and 4.0 dL/g or less.
  • the adhesive strength between the binder (vinylidene fluoride copolymer (A)) and the active material or the current collector is increased.
  • the inherent viscosity indicates logarithmic viscosity.
  • 80 mg of vinylidene fluoride copolymer (A) is dissolved in 20 mL of N,N-dimethylformamide, and the viscosity is measured using an Ubbelohde viscometer in a thermostatic bath at 30° C. Then, the inherent viscosity ( ⁇ i ) is calculated based on the obtained value according to the following formula.
  • ⁇ i (1/C) ⁇ ln( ⁇ / ⁇ 0 )
  • ⁇ is the viscosity of the solution
  • ⁇ 0 is the viscosity of the solvent N,N-dimethylformamide alone
  • C is the concentration of the vinylidene fluoride copolymer in the solution, ie, 0.4 g/dL.
  • An example of a method for producing the vinylidene fluoride copolymer (A) of the above-described embodiment, which contains the structural unit (a2) having a cyclic acid anhydride structure in the main chain, is a method in which the structural unit (a3) is introduced by copolymerizing a monomer having a non-cyclic structure, such as monomethyl itaconate, and then the structural unit (a3) is cyclized to introduce the structural unit (a2).
  • the vinylidene fluoride copolymer (A) is preferably produced by aqueous suspension polymerization, as described below.
  • the above-mentioned method is preferred as a method for introducing the structural unit (a2) from the viewpoint that the monomer to be copolymerized is less susceptible to hydrolysis.
  • the above-mentioned method for producing the vinylidene fluoride copolymer (A) will be described below.
  • the method for producing the vinylidene fluoride copolymer (A) by the above method preferably comprises the steps of: obtaining a polymer having a main chain comprising a heating step of heating the polymer to obtain the structural unit (a2) from the structural unit (a3); has. That is, the above production method includes a step of obtaining a polymer having the structural unit (a1) and the structural unit (a3) as the main chain of the polymer (hereinafter also simply referred to as a "step of obtaining a polymer”), and a heating step of cyclizing the structural unit (a3) in the obtained polymer to the structural unit (a2) (hereinafter also simply referred to as a "heating step").
  • the method for producing the vinylidene fluoride copolymer (A) is not particularly limited, and is usually performed by a method such as suspension polymerization, emulsion polymerization, solution polymerization, etc. From the viewpoint of ease of post-treatment, etc., aqueous suspension polymerization is preferred, and aqueous suspension polymerization is more preferred from the viewpoint of less impurities.
  • the aqueous suspension polymerization method is not particularly limited, and examples include a method in which all monomers used in the copolymerization are copolymerized in an aqueous medium in the presence of a suspending agent and a polymerization initiator.
  • the total monomers used in copolymerization are vinylidene fluoride, which provides the structural unit (a1), and the monomer that provides the structural unit (a3).
  • the amount of the monomer that gives the structural unit (a3) is not particularly limited, and for example, is preferably 0.01 parts by mass or more and 1.0 parts by mass or less, and more preferably 0.02 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of vinylidene fluoride that gives the structural unit (a1).
  • the suspending agent is not particularly limited, and examples thereof include methyl cellulose, propoxylated methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol, polyethylene oxide, gelatin, etc.
  • the amount of the suspending agent used is not particularly limited, and for example, it is preferably 0.005 parts by mass or more and 1.0 parts by mass or less, and more preferably 0.01 parts by mass or more and 0.4 parts by mass or less, relative to 100 parts by mass of the total monomers used in the copolymerization.
  • the polymerization initiator is not particularly limited, and examples thereof include diisopropyl peroxydicarbonate, di-normal propyl peroxydicarbonate, di-normal heptafluoropropyl peroxydicarbonate, isobutyryl peroxide, di(chlorofluoroacyl) peroxide, di(perfluoroacyl) peroxide, and t-butyl peroxypivalate.
  • the amount of the polymerization initiator used is not particularly limited, and for example, it is preferably 0.05 parts by mass or more and 5 parts by mass or less, and more preferably 0.15 parts by mass or more and 2 parts by mass or less, relative to 100 parts by mass of the total monomers used in the copolymerization.
  • the amount of all monomers used in copolymerization is usually 1:1 to 1:10, preferably 1:1 to 1:5, in terms of the mass ratio of the total monomers to water.
  • the polymerization conditions such as the polymerization temperature and polymerization time, when carrying out suspension polymerization are not particularly limited, and for example, known polymerization conditions may be adopted.
  • the polymerization temperature T is appropriately selected according to the 10-hour half-life temperature T10 of the polymerization initiator, and is usually selected in the range of T10-25°C ⁇ T ⁇ T10+25°C.
  • the T10 of t-butyl peroxypivalate and diisopropyl peroxydicarbonate are 54.6°C and 40.5°C, respectively (see NOF Corp. product catalog).
  • the polymerization temperature T is appropriately selected in the range of 29.6°C ⁇ T ⁇ 79.6°C and 15.5°C ⁇ T ⁇ 65.5°C, respectively.
  • the polymerization time is not particularly limited, but taking into consideration productivity, etc., it is preferably 1 to 24 hours.
  • the heating method is not particularly limited, and the polymer to be heated may be in a powder state, or may be heated in a state where the polymer is dispersed in a medium such as water, but from the viewpoint of ease of handling of the polymer, it is preferable to heat the polymer in a powder state.
  • the heating temperature is preferably 60°C or more and 200°C or less, more preferably 100°C or more and 190°C or less, and even more preferably 120°C or more and 180°C or less.
  • the heating time is preferably set appropriately within a range of 30 minutes to 12 hours.
  • the cyclization rate from the structural unit (a3) to the structural unit (a2), when the sum of the structural unit (a2) and the structural unit (a3) in the vinylidene fluoride copolymer (A) is taken as 100.0 mol%, is preferably 1.0 mol% or more and 100.0 mol% or less, preferably 10.0 mol% or more and 99.0 mol% or less, more preferably 30.0 mol% or more and 99.0 mol% or less, even more preferably 50.0 mol% or more and 99.0 mol% or less, and even more preferably 70.0 mol% or more and 99.0 mol% or less.
  • the cyclization rate corresponds to the content of the structural unit (a2) when the total of the structural unit (a2) and the structural unit (a3) in the vinylidene fluoride copolymer (A) is taken as 100.0 mol %.
  • the cyclization rate from the structural unit (a3) to the structural unit (a2) can be calculated from the amount of the structural unit (a3) introduced into the vinylidene fluoride copolymer (A) and the alcohol-treated vinylidene fluoride copolymer described below by the method described below, and then calculated from the following formula (1).
  • Cyclization rate (%) (1 - (amount of structural unit (a3) introduced into vinylidene fluoride copolymer) / (amount of structural unit (a3) introduced into alcohol-treated vinylidene fluoride copolymer) x 100 (Formula 1)
  • the vinylidene fluoride copolymer (A) is immersed in alcohol (R3OH) and heated and stirred at 60°C, and then the unreacted alcohol is removed by filtration and vacuum drying.
  • alcohol R3OH
  • the vinylidene fluoride copolymer subjected to this treatment is referred to as "alcohol-treated vinylidene fluoride copolymer".
  • the heating and stirring time may be arbitrary as long as a peak derived from the cyclized product appearing in the region of 1780 cm -1 to 1800 cm -1 in the spectrum obtained by IR measurement described later (hereinafter, also referred to as "cyclization peak") is not observed.
  • R3 in the alcohol (R3OH) used is the same as the group represented by R3 in the structural unit (a3). In other words, it is necessary to appropriately change the alcohol used depending on the type of group represented by R3 in the structural unit (a3).
  • the alcohol-treated vinylidene fluoride copolymer and the vinylidene fluoride copolymer (A) are each subjected to 1H -NMR measurement. From the obtained spectrum, the integrated intensity of the peak derived from the R3 group of the structural unit (a3) other than vinylidene fluoride (hereinafter also referred to as "VDF") and the integrated intensity of the peak derived from vinylidene fluoride are each obtained. Then, the amount (mol%) of the structural unit (a3) introduced is calculated from the following formula (2).
  • Amount of structural unit (a3) introduced (mol%) ((Ratio of the amount of structural unit (a3) calculated from the integrated intensity of the peak derived from the R3 group of structural unit (a3) of vinylidene fluoride copolymer) / (Ratio of the amount of structural unit (a3) calculated from the integrated intensity of the peak derived from the R3 group of structural unit (a3) of vinylidene fluoride copolymer + Ratio of the amount of VDF calculated from the integrated intensity of the peak derived from VDF)) x 100 (Formula 2)
  • the peaks derived from VDF may be those observed at chemical shifts of 3.20 to 2.70 ppm and 2.43 to 2.10 ppm, assuming that the DMSO-derived peak observed when DMSO-d6 is used as the deuterated solvent is at 2.50 ppm.
  • the peak derived from the R3 group of the structural unit (a3) may be a peak observed at 3.50 to 3.65 ppm when R3 is a methyl group, and a methylene group peak observed at 3.90 to 4.20 ppm when R3 is an ethyl group.
  • the binder contains the above-mentioned vinylidene fluoride copolymer (A).
  • the binder may contain components other than the vinylidene fluoride copolymer (A) (hereinafter, also referred to as "other components") as long as the effects of the present invention are not impaired.
  • other components any known additives may be used, and examples thereof include non-aqueous solvents, plasticizers, dispersants, etc.
  • non-aqueous solvent examples include N-methyl-2-pyrrolidone (hereinafter also referred to as NMP), N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, trimethyl phosphate, acetone, cyclohexanone, methyl ethyl ketone, and tetrahydrofuran. These may be used alone or in combination of two or more.
  • NMP N-methyl-2-pyrrolidone
  • NMP N,N-dimethylformamide
  • N,N-dimethylacetamide dimethylsulfoxide
  • hexamethylphosphoamide dioxane
  • tetrahydrofuran tetramethylurea
  • triethyl phosphate trimethyl phosphate
  • acetone cyclohexanone
  • the binder can be prepared by mixing the vinylidene fluoride copolymer (A) and, if necessary, other components.
  • the electrode mixture means an electrode mixture for a positive electrode.
  • the electrode mixture preferably contains the binder of the above-mentioned embodiment and an active material (B).
  • an electrode mixture containing the active material (B) by adding a binder containing the vinylidene fluoride copolymer (A) having a structural unit (a2) having a cyclic acid anhydride structure in its polymer main chain, an electrode having excellent adhesion to a metal foil can be formed.
  • the content of the binder is not particularly limited, but from the viewpoint of battery performance and adhesion to the metal foil, it is preferably 0.2 parts by mass or more and 15.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 10.0 parts by mass or less, per 100 parts by mass of the active material (B) described later.
  • the active material (B) means a positive electrode active material.
  • the active material (B) includes a lithium-based positive electrode active material containing lithium.
  • the lithium - based positive electrode active material include composite metal chalcogen compounds represented by the general formula LiMY 2 (M is one or more of transition metals such as Co, Ni, Fe, Mn, Cr, and V, and Y is a chalcogen element such as O and S), such as LiCoO 2 and LiNi x Co 1-x O 2 (0 ⁇ x ⁇ 1); composite metal oxides having a spinel structure such as LiMn 2 O 4 ; olivine-type lithium compounds such as LiFePO 4 and LiFeMnPO 4 ; LiNi x Co y Al 1-x-y O 2 (0 ⁇ x+y ⁇ 1); and the like.
  • the positive electrode active material may be a compound having a coating on the surface thereof. Furthermore, the positive electrode active material may be a commercially available product.
  • the electrode mixture may contain the binder of the above-mentioned embodiment and components other than the active material (B) (hereinafter, also referred to as "other components") as long as the effect of the present invention is not impaired.
  • the other components any known additives can be used, for example, a conductive assistant, a non-aqueous solvent, an insulating inorganic filler such as alumina, magnesia, or silica, an insulating organic filler such as polytetrafluoroethylene, polyimide, or polyacrylonitrile, a plasticizer, a dispersant, a flame retardant, etc.
  • Examples of the conductive additive (C) include carbon black, carbon nanotubes, etc. These may be used alone or in combination of two or more.
  • the amount of the conductive additive (C) is not particularly limited, but is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.2 parts by mass or more and 4.0 parts by mass or less, per 100 parts by mass of the active material (B).
  • non-aqueous solvent examples include N-methyl-2-pyrrolidone (hereinafter also referred to as "NMP"), N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, trimethyl phosphate, acetone, cyclohexanone, methyl ethyl ketone, and tetrahydrofuran. These may be used alone or in combination of two or more.
  • NMP N-methyl-2-pyrrolidone
  • NMP N,N-dimethylformamide
  • N,N-dimethylacetamide dimethylsulfoxide
  • hexamethylphosphoamide dioxane
  • tetrahydrofuran tetramethylurea
  • triethyl phosphate trimethyl phosphate
  • acetone cyclohexan
  • the electrode mixture can be prepared by mixing the binder of the above-mentioned embodiment, the active material (B), and other components as necessary.
  • the mixing method is not particularly limited, and the components can be mixed by a known method.
  • the electrode means a positive electrode.
  • the electrode has a current collector and an electrode mixture layer formed on the surface of the current collector and obtained by drying the electrode mixture of the above-mentioned embodiment.
  • the electrode mixture layer contains the vinylidene fluoride copolymer (A) containing a structural unit (a2) having a cyclic acid anhydride structure in the main chain in the binder contained in the electrode mixture.
  • vinylidene fluoride copolymer (A) By containing such vinylidene fluoride copolymer (A), the electrode exhibits an effect of excellent adhesion to the metal foil.
  • the current collector is a terminal for taking out electricity.
  • the material of the current collector is not particularly limited, and metal foil or metal mesh of aluminum, copper, iron, stainless steel, steel, nickel, titanium, etc. can be used.
  • the current collector may be a medium in which the above-mentioned metal foil or metal mesh is applied to the surface.
  • the metal foil or metal mesh may be a medium in which a surface treatment is performed using a non-metallic substance such as a polymer or conductive carbon.
  • the electrode mixture layer contains the electrode mixture of the above-mentioned embodiment and is disposed on at least one surface of the current collector.
  • the electrode mixture of the above-mentioned embodiment is applied onto the current collector and dried.
  • the coating method is not particularly limited, and for example, the doctor blade method, reverse roll method, comma bar method, gravure method, air knife method, die coating method, dip coating method, etc. can be applied.
  • the drying temperature is, for example, preferably 80° C. or more and 300° C. or less, more preferably 90° C. or more and 250° C. or less, and even more preferably 100° C. or more and 200° C. or less.
  • the drying time is, for example, preferably from 10 seconds to 300 minutes, more preferably from 1 minute to 200 minutes, and even more preferably from 10 minutes to 100 minutes.
  • the drying may be performed multiple times at different temperatures. Pressure may be applied during the drying.
  • the battery means a non-aqueous electrolyte secondary battery.
  • the battery is provided with the electrode of the above-mentioned embodiment.
  • a non-aqueous electrolyte secondary battery conventionally known members other than the positive electrode, such as a negative electrode and a separator, can be used.
  • Example of binder preparation> ⁇ Examples 1 to 5 and Comparative Example 1>
  • the following vinylidene fluoride copolymers A1 to A6 were prepared as vinylidene fluoride copolymers (A) according to the following method.
  • the vinylidene fluoride copolymers A1 to A6 were used as binders in the preparation of electrode mixtures and electrodes described below.
  • the inherent viscosity, crystalline melting temperature, amount of monomethyl itaconate (hereinafter also referred to as "MI") introduced as a copolymerization monomer and cyclization rate, and content of structural unit (a2) in which a structural unit derived from MI was cyclically dehydrated were measured for the obtained vinylidene fluoride copolymers (A) according to the following method.
  • ⁇ i (1/C) ⁇ ln( ⁇ / ⁇ 0 )
  • ⁇ is the viscosity of the solution
  • ⁇ 0 is the viscosity of the solvent N,N-dimethylformamide alone
  • C is the concentration of vinylidene fluoride copolymer (A) in the solution, that is, 0.4 g/dL.
  • the crystalline melting temperature of vinylidene fluoride copolymer (A) was determined by calorimetry using a differential scanning calorimeter (DSC). Specifically, vinylidene fluoride copolymer (A) was heated from 30°C to 230°C at 10°C/min (first heating), cooled from 230°C to 30°C at 10°C/min (first cooling), and further heated from 30°C to 230°C at 10°C/min (second heating), and the melting peak was determined by DSC. The maximum melting peak temperature observed in the second heating was determined as the crystalline melting temperature of vinylidene fluoride copolymer.
  • DSC differential scanning calorimeter
  • MI amount of structural unit (a3) introduced
  • the amount of MI (structural unit (a3)) introduced into the vinylidene fluoride copolymer (A) was determined by 1 H-NMR. Specifically, 1 H-NMR of the vinylidene fluoride copolymer (A) dissolved in DMSO-d6 was measured using a nuclear magnetic resonance apparatus (NMR, JEOL, JNM -ECZ600R/S1, frequency 600 MHz). From the obtained spectrum, the integrated intensity of the peak derived from MI other than vinylidene fluoride (hereinafter also referred to as "VDF”) and the integrated intensity of the peak derived from vinylidene fluoride were each obtained.
  • VDF integrated intensity of the peak derived from MI other than vinylidene fluoride
  • the amount of MI introduced (mol%) was calculated from the ratio of the substance amount ratio of MI calculated from the integrated intensity of the peak derived from MI to the sum of the substance amount ratio of MI calculated from the integrated intensity of the peak derived from MI and the substance amount ratio of VDF calculated from the integrated intensity of the peak derived from VDF.
  • the cyclization rate in this embodiment refers to the content (mol%) of the structural unit derived from MI, which is cyclically dehydrated, relative to the total amount of the structural unit derived from MI and the structural unit derived from MI, which is cyclically dehydrated, contained in the vinylidene fluoride copolymer (A).
  • the cyclization rate of MI in the vinylidene fluoride copolymer (A) was calculated by determining the amount of MI introduced into the vinylidene fluoride copolymer (A) and the vinylidene fluoride copolymer treated with methanol, which will be described later, by the above-mentioned method, and calculating the cyclization rate by the following formula (3).Specifically, it was calculated by the following procedure.
  • the vinylidene fluoride copolymer (A) shown in the examples and comparative examples described later was immersed in methanol, heated and stirred at 60°C, and then filtered and vacuum dried to remove unreacted methanol.
  • the vinylidene fluoride copolymer subjected to this treatment is referred to as "vinylidene fluoride copolymer treated with methanol".
  • the heating and stirring time may be arbitrary as long as a peak derived from the cyclized product appearing in the region of 1780 cm -1 to 1800 cm -1 in the spectrum obtained by the IR measurement described later (hereinafter, also referred to as "cyclization peak") is not observed.
  • cyclization peak a peak derived from the cyclized product appearing in the region of 1780 cm -1 to 1800 cm -1 in the spectrum obtained by the IR measurement described later
  • cyclization peak a peak derived from the cyclized product appearing in the region of 1780 cm -1 to 1800 cm -1 in the spectrum obtained by the IR measurement described later
  • Cyclization rate (%) (1 - (amount of MI introduced into vinylidene fluoride copolymer shown in the examples or comparative examples) / (amount of MI introduced into vinylidene fluoride copolymer treated with methanol)) x 100 (Equation 3)
  • Example 1 Preparation of vinylidene fluoride copolymer A1
  • a cellulose-based suspension agent Metallose SM-100, manufactured by Shin-Etsu Chemical Co., Ltd.
  • 1.08 g of monomethyl itaconate 14.09 g
  • a polymerization initiator 50 wt% t-butyl peroxypivalate-HFE-347pc-f solution
  • 2168 g of vinylidene fluoride were charged, and the temperature was raised to 55°C over 2 hours with stirring.
  • MI monomethyl itaconate
  • the yield of the obtained vinylidene fluoride copolymer was 88%, the inherent viscosity ⁇ i was 2.6 dL/g, and the amount of MI introduced was 0.36 mol %.
  • the obtained vinylidene fluoride copolymer was subjected to heat treatment at 80° C. for 10 hours under a nitrogen gas flow to obtain vinylidene fluoride copolymer A1 having a structural unit (a2) having a cyclic acid anhydride structure in the main chain.
  • the cyclization rate of this vinylidene fluoride copolymer A1 was 1.6%.
  • Example 2 Preparation of vinylidene fluoride copolymer A2
  • Vinylidene fluoride copolymer A2 was obtained in the same manner as in Example 1, except that the heat treatment in Example 1 was carried out at 100° C. for 4 hours under a nitrogen stream instead of at 80° C. for 10 hours under a nitrogen stream.
  • the cyclization rate of this vinylidene fluoride copolymer A2 was 11.4%.
  • Example 3 Preparation of vinylidene fluoride copolymer A3
  • Vinylidene fluoride copolymer A3 was obtained in the same manner as in Example 1, except that the heat treatment in Example 1 was carried out at 130° C. for 1 hour under a nitrogen stream instead of at 80° C. for 10 hours under a nitrogen stream.
  • the cyclization rate of this vinylidene fluoride copolymer A3 was 32.2%.
  • Example 4 Preparation of vinylidene fluoride copolymer A4
  • Vinylidene fluoride copolymer A4 was obtained in the same manner as in Example 1, except that the heat treatment in Example 1 was carried out at 130° C. for 4 hours under a nitrogen stream instead of at 80° C. for 10 hours under a nitrogen stream.
  • the cyclization rate of this vinylidene fluoride copolymer A4 was 65.3%.
  • Example 5 Preparation of vinylidene fluoride copolymer A5
  • Vinylidene fluoride copolymer A5 was obtained in the same manner as in Example 1, except that the heat treatment in Example 1 was carried out at 140° C. for 6.5 hours under a nitrogen stream instead of at 80° C. for 10 hours under a nitrogen stream.
  • the cyclization rate of this vinylidene fluoride copolymer A5 was 82.7%.
  • Vinylidene fluoride polymer A6 was obtained in the same manner as in Example 1, except that the heat treatment in Example 1 was not carried out.
  • B1 Nickel-cobalt-manganese ternary lithium-based composite metal oxide (Ni content 83%, Co content 8%, Mn content 8%, specific surface area 0.4 m 2 /g, average particle size D 50 12.1 ⁇ m)
  • C1 Carbon black (Super-P, manufactured by Timcal)
  • 100 parts by mass of the active material (B) and 1 part by mass of the conductive assistant (C) were added to a polyethylene cup and kneaded for 1 minute at 800 rpm using a mixer (AR-310, manufactured by Thinky Corporation) to obtain a primary kneaded mixture.
  • the above primary kneaded product was added with a binder solution containing 1 part by mass of each of the binders of Examples 1 to 5 and Comparative Example 1 obtained above, and a nonaqueous solvent (S) in an amount such that the solid content concentration relative to the total mass of the electrode mixture was 80% by mass, and the mixture was kneaded at 2000 rpm for 1 minute using the mixer to form a paste.
  • the electrode mixture heated by kneading was allowed to cool naturally until the temperature reached room temperature, and was further kneaded at 2000 rpm for 1 minute. This operation was performed five times to obtain a slurry-like positive electrode mixture of Examples 1A to 5A and Comparative Example 1A.
  • Example of electrode preparation> ⁇ Examples 1B to 5B and Comparative Example 1B>
  • the resulting electrode mixtures of Examples 1A to 5A and Comparative Example 1A were used to prepare positive electrodes of Examples 1B to 5B and Comparative Example 1B, and the peel strength of the electrodes was measured.
  • each of the electrode mixtures was applied onto an aluminum foil having a thickness of 15 ⁇ m using a bar coater, and then this was dried for 30 minutes at 110° C. in a nitrogen atmosphere using a thermostatic chamber, thereby obtaining single-sided coated electrodes of Examples 1B to 5B and Comparative Example 1B having a dry mixture basis weight of 300 g/ m2 .

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JPH02604A (ja) * 1988-12-28 1990-01-05 Daikin Ind Ltd 含フッ素共重合体
US20010012880A1 (en) * 1997-10-15 2001-08-09 Wheland Robert C. Copolymers of maleic anhydride or acid and fluorinated oleffins
WO2004092257A1 (ja) * 2003-04-16 2004-10-28 Kureha Corporation フッ化ビニリデン系樹脂多孔膜及びその製造方法
WO2010035587A1 (ja) * 2008-09-26 2010-04-01 株式会社クレハ 非水電解質二次電池用負極合剤、非水電解質二次電池用負極および非水電解質二次電池

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US3357936A (en) * 1964-02-05 1967-12-12 Dow Chemical Co Coating compositions comprising alkyd resins prepared from styrene-maleic anhydride copolymers, polyol and fatty acid
US5797206A (en) 1996-12-26 1998-08-25 Smith & Wesson Corp. Method for reversibly converting a traditional double action pistol to a single action, target pistol
JP5797206B2 (ja) 2010-12-28 2015-10-21 株式会社クレハ フッ化ビニリデン系共重合体、および該共重合体の用途
CN110707357B (zh) * 2019-10-23 2021-05-07 北京卫蓝新能源科技有限公司 一种核壳结构的凝胶聚合物电解质及其制备方法和应用

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02604A (ja) * 1988-12-28 1990-01-05 Daikin Ind Ltd 含フッ素共重合体
US20010012880A1 (en) * 1997-10-15 2001-08-09 Wheland Robert C. Copolymers of maleic anhydride or acid and fluorinated oleffins
WO2004092257A1 (ja) * 2003-04-16 2004-10-28 Kureha Corporation フッ化ビニリデン系樹脂多孔膜及びその製造方法
WO2010035587A1 (ja) * 2008-09-26 2010-04-01 株式会社クレハ 非水電解質二次電池用負極合剤、非水電解質二次電池用負極および非水電解質二次電池

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