Classifications

• • 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
  • C08F261/00—Macromolecular compounds obtained by polymerising monomers on to polymers of oxygen-containing monomers as defined in group C08F16/00
  • C08F261/02—Macromolecular compounds obtained by polymerising monomers on to polymers of oxygen-containing monomers as defined in group C08F16/00 on to polymers of unsaturated alcohols
  • C08F261/04—Macromolecular compounds obtained by polymerising monomers on to polymers of oxygen-containing monomers as defined in group C08F16/00 on to polymers of unsaturated alcohols on to polymers of vinyl alcohol
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/04—Acids; Metal salts or ammonium salts thereof
  • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/42—Nitriles
  • C08F220/44—Acrylonitrile
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L29/00—Compositions of homopolymers or 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 an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
  • C08L29/02—Homopolymers or copolymers of unsaturated alcohols
  • C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/003—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/06—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0569—Liquid materials characterised by the solvents
• • 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
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • 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
  • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
  • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
  • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• • 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
• • 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
  • H01M4/624—Electric conductive fillers
  • H01M4/625—Carbon or graphite
• • 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
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/661—Metal or alloys, e.g. alloy coatings
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/028—Positive electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0037—Mixture of solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0048—Molten electrolytes used at high temperature
  • H01M2300/0051—Carbonates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
• • 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 has been made in view of such problems, and uses a composition that serves as a binder having an excellent balance between suppression of deterioration of battery performance in a high-capacity electrode, high-temperature storage characteristics, and DC resistance. It provides a slurry for a positive electrode, a positive electrode, and a secondary battery.
• the composition further comprises a free polymer, the free polymer has no covalent bond with the graft copolymer, the free polymer is a polymer comprising a polyvinyl alcohol structure, and / or said first. Contains at least a polymer containing one monomeric unit.
• the graft copolymer further comprises a cross-linked portion derived from a cross-linking agent.
• the crosslinked portion comprises an ether structure.
• the composition contains 0.2 to 10 parts by mass of the structure derived from the cross-linking agent when the composition is 100 parts by mass.
• the present invention provides a composition that serves as a binder that suppresses deterioration of battery performance with a high-capacity electrode, has excellent high-temperature storage characteristics, and has an excellent balance of DC resistance, a slurry for a positive electrode using the composition, a positive electrode, and a secondary battery. offer.
• composition according to one embodiment of the present invention can be used as a composition for a positive electrode.
• the positive electrode composition according to one embodiment of the present invention includes the composition according to one embodiment of the present invention, and preferably comprises the composition according to one embodiment of the present invention.
• the composition according to one embodiment of the present invention is a composition containing a graft copolymer, and the graft copolymer has a stem polymer and a branch polymer, preferably a stem polymer and a plurality of branch polymers. Have.
• the polymer may be referred to as a copolymer.
• the graft copolymer according to the embodiment of the present invention can further contain a cross-linked portion derived from a cross-linking agent.
• the cross-linked portion means a structure derived from a cross-linking agent, which cross-links the branch polymers, cross-links the stem polymer and the branch polymer, or cross-links the stem polymers.
• at least the first monomer is graft-copolymerized with the stem polymer to crosslink either the stem polymer or the branch polymer with either the stem polymer or the branch polymer. By doing so, you can get it.
• the composition according to one embodiment of the present invention may also contain, as a free polymer, a polymer containing a structure derived from a cross-linking agent, in addition to the polymer containing the first monomer.
• the graft copolymer according to the embodiment of the present invention has a second monomer unit containing an ether structure, and a first monomer unit and a second monomer unit, as long as the effects of the present invention are not impaired. It may contain a monomer unit other than the above.
• the composition according to one embodiment of the present invention contains, as a free polymer, a polymer containing a second monomer unit, and a monomer unit other than the first monomer unit and the second monomer unit. It can also be a polymer.
• the graft ratio of the graft copolymer is preferably 40 to 3000%, more preferably 150 to 900%. From the viewpoint of solubility, the graft ratio is preferably in the above range. When the graft ratio is at least the above lower limit, the solubility in a solvent (for example, NMP (N-methyl-2-pyrrolidone)) is improved when the slurry is made, and when it is at least the above upper limit, the viscosity of the slurry is lowered. The fluidity of the slurry is improved.
• a solvent for example, NMP (N-methyl-2-pyrrolidone)
• the average degree of polymerization of the polyvinyl alcohol structure in the composition is preferably 300 to 4000, and more preferably 500 to 2000.
• the stability of the slurry is particularly high. Further, it is preferably in the above range from the viewpoint of solubility, binding property, and viscosity of the binder.
• the average degree of polymerization is 300 or more, the binding property between the binder and the active material and the conductive auxiliary agent is improved, and the durability is improved.
• the average degree of polymerization is 4000 or less, the solubility is improved and the viscosity is lowered, so that the slurry for a positive electrode can be easily produced.
• the composition according to one embodiment of the present invention may further contain a free polymer.
• the free polymer is a polymer that does not have a covalent bond with the graft copolymer, and includes at least a polymer containing a polyvinyl alcohol structure and / or a polymer containing the first monomer unit.
• the polymer having a polyvinyl alcohol structure mainly means a stem polymer that was not involved in graft copolymerization.
• the polymer containing the first monomer unit is a homopolymer of the first monomer, a copolymer containing the first monomer unit and the second monomer unit, the first monomer and the first monomer.
• the second monomer used in synthesizing the graft polymer is a monomer having an ether structure, preferably a (meth) acrylic acid ester derivative having an ether structure, a styrene derivative having an ether structure, and the like. It is a monomer such as a polysubstituted ethylene derivative or a vinyl ether derivative. Among these, a (meth) acrylic acid ester derivative having an ether structure is preferable. Among the (meth) acrylic acid ester derivatives having an ether structure, the (meth) acrylic acid ester derivative represented by the following general formula (A) is preferable.
• Y is preferably ⁇ (AO) n—R.
• AO is an oxyalkylene group.
• the number of carbon atoms of the oxyalkylene group is preferably 1 to 18, and more preferably 2 to 10.
• As the oxyalkylene group one or more of an ethylene oxide group and a propylene oxide group is most preferable, and an ethylene oxide group is more preferable.
• n is a number of 0 or more.
• n is preferably 1 or more.
• n is preferably 30 or less, more preferably 10 or less.
• R 1 , R 2 , R 3 , and R are hydrogen (H), a hydrocarbon group which may be substituted, an ether group, or the like.
• the hydrocarbon group or ether group which may be substituted is a hydrocarbon group or an ether group having 1 to 20 carbon atoms.
• the ether group is a functional group having an ether bond, and for example, an alkyl ether group.
• R 1 , R 2 , R 3 , and R unsubstituted is preferable.
• R 1 , R 2 , R 3 , and R may be the same or different.
• R a hydrocarbon group is preferable.
• the hydrocarbon group one or more of a methyl group and an ethyl group are preferable.
• the (meth) acrylic acid ester derivative alkoxypolyalkylene glycol (meth) acrylate is preferable.
• the positive electrode serves as a binder with an excellent balance of suppression of deterioration of battery performance in high-capacity electrodes, high-temperature storage characteristics (high-temperature storage characteristics), and DC resistance.
• Compositions for use may be provided.
• the content of the polyvinyl alcohol structure in the composition is the total amount of the polyvinyl alcohol structure in the graft copolymer and the polyvinyl alcohol structure in the free polymer containing polyvinyl alcohol contained in the composition. Is shown.
• the composition according to the embodiment of the present invention preferably contains 3 to 80 parts by mass of the first monomer unit derived from the first monomer when the composition is 100 parts by mass. It is more preferably 5 to 70 parts by mass, for example, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80 parts by mass. It may be within the range between any two of the numerical values exemplified here. By setting it to the above lower limit or more, a binder having binding property can be obtained, and by setting it to the above upper limit or less, oxidation resistance can be maintained.
• the content of the first monomer unit in the composition refers to the first monomer unit and the first monomer unit in the graft copolymer contained in the composition. The total amount of the first monomer unit in the containing free polymer is shown.
• the content of the structure derived from the cross-linking agent in the composition is the structure derived from the cross-linking agent bonded to the graft copolymer contained in the composition and the cross-linking in the free polymer.
• the total amount of the structure derived from the agent is shown.
• the composition according to the embodiment of the present invention preferably contains 0 to 20 parts by mass of the second monomer unit derived from the second monomer when the composition is 100 parts by mass. , 0 to 15 parts by mass, for example, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 parts by mass, and the numerical values exemplified here are used. It may be within the range between any two.
• the composition according to one embodiment of the present invention may also be free of the second monomer unit. By setting the content of the second monomer unit within the above range, a binder having an appropriate gel fraction and an appropriate flexibility can be obtained.
• the content of the second monomer unit in the composition refers to the second monomer unit and the second monomer unit in the graft copolymer contained in the composition. The total amount of the second monomer unit in the containing free polymer is shown.
• the composition according to the embodiment of the present invention preferably contains 0.1 to 20 parts by mass in total of the structure derived from the cross-linking agent and the second monomer unit when the composition is 100 parts by mass. , 0.1 to 15 parts by mass is more preferable.
• the total content of the structure derived from the cross-linking agent and the second monomer unit is, for example, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20 parts by mass, and may be within the range between any two of the numerical values exemplified here.
• composition according to one embodiment of the present invention by controlling the swelling rate within the above range, it is possible to maintain the pore volume, especially in the high rate region, while having appropriate flexibility. Therefore, it is presumed that it has high battery characteristics and can suppress a decrease in discharge capacity during high temperature storage.
• the swelling rate of the composition with respect to the electrolytic solution indicates the mass change before and after the film made of the composition is immersed in the electrolytic solution for a predetermined time and at a predetermined temperature.
• the swelling rate can be determined by, for example, the following method.
• the obtained composition is dissolved in NMP to prepare a 4% by mass NMP solution.
• 5.6 g of the obtained solution is added to a petri dish of PTFE (tetrafluoroethylene) and dried in a blower dryer at 105 ° C. for 8 hours to obtain a film having a thickness of 250 ⁇ m.
• the central portion of the obtained film is cut into a size of 5 mm ⁇ 5 mm to obtain a test film.
• the swelling rate under different conditions can be obtained. For example, by setting the immersion condition in the electrolytic solution to 60 ° C. for 48 hours, the swelling rate when immersed in the electrolytic solution at 60 ° C. for 48 hours can be obtained, and the swelling rate can be evaluated in a short time.
• the composition according to one embodiment of the present invention contains a component derived from PVA and a component derived from the first monomer, and optionally, a component derived from the second monomer and / or a cross-linking agent. Contains ingredients derived from.
• the content of each component in the composition can be estimated from the amount charged for graft polymerization.
• the content of each component can be calculated more accurately by obtaining the reaction rate of each component by the following method. Further, the content of each component can also be calculated from the integral ratio by NMR of the obtained composition.
• the reaction rate of polyvinyl alcohol can be determined by the following method. First, the concentration of PVA in the raw material solution is determined by the absorbance. Next, a polymerization reaction is carried out to obtain a polymerization reaction solution, and 50 g of the obtained polymerization reaction solution is centrifuged at 3000 G for 30 minutes to obtain a supernatant. The absorbance in the supernatant is measured and the PVA concentration is measured. The reaction rate of PVA is determined by ⁇ 1- (concentration of PVA in the supernatant) / (concentration of PVA at the time of preparation) ⁇ ⁇ 100. The reaction rate of the first monomer, the second monomer and the cross-linking agent can be determined by the following method.
• composition of each component is calculated from the intensity of the signal corresponding to PVA, the first monomer, the second monomer, and the cross-linking agent in the obtained spectrum with PVA as a reference. Comparing the composition calculated from NMR with the composition of each component at the time of charging, how much of the charged first monomer, second monomer and cross-linking agent, the first monomer and the second The reaction rate indicating whether the monomer and the cross-linking agent are contained in the composition is calculated.
• a free polymer containing at least one of the group consisting of a first monomer, a second monomer, and a cross-linking agent may be produced.
• the calculation of the graft ratio requires a step of separating the free polymer from the graft copolymer.
• the free polymer is soluble in dimethylformamide (hereinafter abbreviated as DMF), but PVA and graft copolymers are insoluble in DMF. By utilizing this difference in solubility, the free polymer can be separated by an operation such as centrifugation.
• the GPC measurement can be performed under the following conditions, for example.
• Method for producing a composition containing a graft copolymer The method for producing a composition containing a graft copolymer according to an embodiment of the present invention is not particularly limited, but the method for producing a composition according to an embodiment of the present invention is at least. It is preferable to include a graft copolymerization step in which a raw material containing polyvinyl alcohol and a first monomer is graft-copolymerized. That is, the composition according to one embodiment of the present invention is preferably obtained by a production method including a graft copolymerization step of graft-polymerizing a raw material containing at least polyvinyl alcohol and a first monomer.
• the production method according to the embodiment of the present invention further comprises a vinyl acetate polymerization step of polymerizing vinyl acetate to obtain polyvinyl acetate, and a saponification step of saponifying the obtained polyvinyl acetate to obtain polyvinyl alcohol. It is preferable to include it.
• Method for producing polyvinyl alcohol (PVA) As a method for polymerizing polyvinyl acetate, any known method such as bulk polymerization or solution polymerization can be used.
• Examples of the initiator used for the polymerization of polyvinyl acetate include azo-based initiators such as azobisisobutyronitrile, and organic peroxides such as benzoyl peroxide and bis (4-t-butylcyclohexyl) peroxydicarbonate. Things etc. can be mentioned.
• the saponification reaction of polyvinyl acetate can be carried out, for example, by a method of saponification in an organic solvent in the presence of a saponification catalyst.
• organic solvent examples include methanol, ethanol, propanol, ethylene glycol, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, benzene, toluene and the like. One or more of these may be used. Of these, methanol is preferred.
• the production method according to the embodiment of the present invention preferably includes a step of graft-copolymerizing a raw material containing at least polyvinyl alcohol and the first monomer, and the raw material containing at least polyvinyl alcohol and the first monomer. Can further include a cross-linking agent. Further, the raw material containing at least polyvinyl alcohol and the first monomer can further contain the second monomer.
• the gel fraction is adjusted within the above range by adjusting the type and amount of the raw material to be used at the time of graft copolymerization, the polymerization conditions and the like.
• the raw material to be subjected to graft copolymerization when the raw material to be subjected to graft copolymerization is 100 parts by mass, the raw material to be subjected to graft copolymerization preferably contains 0.2 to 10 parts by mass of a cross-linking agent, and more preferably 0.5 to 8 parts by mass. It is preferable to contain 1 to 5 parts by mass, and it is particularly preferable to contain 1 to 5 parts by mass.
• the content of the cross-linking agent in the raw material to be subjected to the graft copolymerization is, for example, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by mass. Yes, it may be within the range between any two of the numerical values exemplified here.
• a solution polymerization method As a method of graft-copolymerizing a monomer to polyvinyl alcohol, for example, a solution polymerization method can be mentioned.
• the solvent used include water, dimethyl sulfoxide, N-methylpyrrolidone and the like.
• the graft copolymer according to the embodiment of the present invention can be used by dissolving it in a solvent.
• the solvent include dimethyl sulfoxide and N-methylpyrrolidone. These solvents may be contained in the composition and the slurry for the positive electrode described later.
• Compositions according to one embodiment of the present invention may contain other components, for example, resins and the like, as long as the effects of the present invention are not impaired.
• resins include fluororesins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene, styrene-butadiene-based copolymers (styrene-butadiene rubber and the like), acrylic-based copolymers and the like.
• PVDF polyvinylidene fluoride
• styrene-butadiene-based copolymers styrene-butadiene rubber and the like
• acrylic-based copolymers and the like acrylic-based copolymers and the like.
• a fluororesin, particularly polyvinylidene fluoride is preferable from the viewpoint of stability.
• the positive electrode slurry according to the embodiment of the present invention preferably has a solid content of 0.1 to 20% by mass based on the total solid content in the positive electrode slurry. It is preferable, and it is more preferable that it is 1 to 10% by mass.
• the positive electrode according to the embodiment of the present invention is formed by applying a positive electrode slurry containing a composition, a conductive auxiliary agent, and a positive electrode active material to be used as needed on a current collector such as an aluminum foil. It can be produced by removing the solvent contained in the slurry by heating and further pressurizing the current collector and the electrode mixture layer with a roll press or the like to bring them into close contact with each other. That is, a positive electrode having a metal foil and a coating film of a slurry for a positive electrode formed on the metal foil can be obtained.
• the conductive auxiliary agent is preferably at least one selected from the group consisting of (i) fibrous carbon, (ii) carbon black and (iii) a carbon composite in which fibrous carbon and carbon black are interconnected.
• fibrous carbon include gas-phase grown carbon fibers, carbon nanotubes, carbon nanofibers and the like.
• carbon black include acetylene black, furnace black and Ketjen black (registered trademark).
• These conductive auxiliaries may be used alone or in combination of two or more. Among these, one or more selected from acetylene black, carbon nanotubes and carbon nanofibers is preferable from the viewpoint of having a high effect of improving the dispersibility of the conductive auxiliary agent.
• a positive electrode active material may be used.
• the positive electrode active material is preferably a positive electrode active material capable of reversibly occluding and releasing cations.
• the positive electrode active material is preferably a lithium-containing composite oxide containing Mn having a volume resistivity of 1 ⁇ 10 4 ⁇ ⁇ cm or more, or a lithium-containing polyanion compound.
• the positive electrode slurry according to the embodiment of the present invention preferably has a solid content of 50 to 99.8% by mass, preferably 80 to 99.8% by mass, based on the total solid content in the positive electrode slurry. It is more preferably to 99.5% by mass, and most preferably 95 to 99.0% by mass.
• the binder for the negative electrode is not particularly limited, and for example, polyvinylidene fluoride, polytetrafluoroethylene, a styrene-butadiene copolymer (styrene butadiene rubber, etc.), an acrylic copolymer, and the like can be used.
• a fluororesin is preferable.
• the fluororesin one or more of the group consisting of polyvinylidene fluoride and polytetrafluoroethylene is more preferable, and polyvinylidene fluoride is most preferable.
• Examples of the negative electrode active material used for the negative electrode include carbon materials such as graphite, polyacene, carbon nanotubes, and carbon nanofibers, alloy materials such as tin and silicon, and oxidation of tin oxide, silicon oxide, lithium titanate, and the like. Materials and the like can be mentioned. One or more of these may be used.
• As the metal foil for the negative electrode foil-shaped copper is preferably used, and the thickness is preferably 5 to 30 ⁇ m from the viewpoint of processability.
• the negative electrode can be manufactured by using the slurry for the negative electrode and the metal foil for the negative electrode by the method according to the method for manufacturing the positive electrode described above.
• any one having sufficient strength such as an electrically insulating porous film, a net, a non-woven fabric, and a fiber, can be used.
• a solution having low resistance to ion transfer of the electrolytic solution and having excellent solution retention is preferable.
• the material is not particularly limited, and examples thereof include inorganic fibers such as glass fibers or organic fibers, olefins such as polyethylene and polypropylene, synthetic resins such as polyester, polytetrafluoroethylene and polyflon, and layered composites thereof. From the viewpoint of binding and stability, olefins or layered complexes thereof are preferable.
• the olefin one or more of the group consisting of polyethylene and polypropylene is preferable.
• LiCl, LiBr, LiI, LiB (C 2 H 5 ) 4 LiCF 3 SO 3 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN ( Examples thereof include C 2 F 5 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , and lower fatty acid lithium carboxylate.
• the electrolytic solution for dissolving the electrolyte is not particularly limited.
• the electrolytic solution include carbonates such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate, lactones such as ⁇ -butyrolactone, trimethoxymethane, 1,2-dimethoxyethane, diethyl ether and 2 -Esters such as ethoxyethane, tetrahydrofuran and 2-methyltetra, sulfoxides such as dimethylsulfoxide, oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane, acetonitrile, nitromethane and N-methyl- Nitrogen-containing compounds such as 2-pyrrolidone, esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethy
• Acid esters such as dimethylformamide and dimethylacetamide, glyme such as diglyme, triglime and tetraglyme, ketones such as acetone, diethylketone, methylethylketone and methylisobutylketone, sulfolanes such as sulfolane, 3-methyl- Examples thereof include oxazolidinones such as 2-oxazolidinone, and sulton such as 1,3-propanesartone, 4-butanesultone and naphthalusulton.
• the electrolytic solution preferably contains carbonates, and more preferably contains ethylene carbonate and diethyl carbonate.
• an electrolyte solution in which LiPF 6 is dissolved in carbonates is preferable, an electrolyte solution in which LiPF 6 is dissolved in a mixed solution containing ethylene carbonate and diethyl carbonate is more preferable, and LiPF 6 is referred to as ethylene carbonate.
• An electrolyte solution prepared by dissolving diethyl carbonate in a mixed solution in which a volume ratio of 1: 2 is mixed is even more preferable.
• the concentration of the electrolyte in the solution varies depending on the electrode used and the electrolytic solution, but is preferably 0.5 to 3 mol / L.
• the application of the lithium ion secondary battery according to the embodiment of the present invention is not particularly limited, but for example, a digital camera, a video camera, a portable audio player, a portable AV device such as a portable liquid crystal TV, a notebook computer, a smartphone, and a mobile PC.
• a digital camera a digital camera
• a video camera a portable audio player
• a portable AV device such as a portable liquid crystal TV
• a notebook computer a notebook computer
• smartphone a smartphone
• a mobile PC a mobile PC.
• mobile information terminals such as mobile information terminals, portable game devices, electric tools, electric bicycles, hybrid vehicles, electric vehicles, and power storage systems.
• Example 1 As PVA, PVA (B-17) manufactured by Denka Co., Ltd. was used. Table 1 shows the average degree of polymerization and the degree of saponification of the obtained PVA. The average degree of polymerization and saponification of PVA were measured based on JIS K 6726.
• composition > 1804 parts by mass of pure water is charged in a reaction vessel, nitrogen gas is bubbled to deoxidize, and then 100 parts by mass of partially saponified PVA (saponification degree 85.6%, polymerization degree 1700) is charged at room temperature and the temperature rises to 90 ° C. Dissolved by warming.
• the reaction vessel was adjusted to 60 ° C., and 170 parts by mass of a 10% ammonium persulfate aqueous solution deoxidized by bubbling nitrogen gas was added in a batch, and 96 parts by mass of acrylonitrile and the cross-linking agent oligoethylene glycol diacrylate (general formula (B)) were added.
• Ethylene glycol repeats n 9, R 21 , and R 22 are hydrogen.
• Table 1 shows the composition and the like of the composition containing the obtained graft copolymer.
• composition ratio of each component was calculated based on the reaction rate of Example 2 described later.
• the composition ratio includes a free polymer (homoPAN) which is a homopolymer of the first monomer. The results are shown in Table 1.
• NMP N-methyl-2-pyrrolidone
• the prepared slurry for positive electrode was applied to an aluminum foil having a thickness of 20 ⁇ m at 140 g / m 2 with an automatic coating machine, and pre-dried at 105 ° C. for 30 minutes. Next, it was pressed with a roll press machine at a linear pressure of 0.1 to 3.0 ton / cm, and the thickness of the positive electrode plate was adjusted to 75 ⁇ m. Further, the positive electrode plate was punched into a circle of 13 ⁇ mm. In order to completely remove volatile components such as residual solvent and adsorbed water, the product was dried at 170 ° C. for 6 hours to obtain a positive electrode.
• the electrode area density was 29.0 mg / cm 2 , and the volume density was 3.4 g / cm 3 .
• a 2032 type coin cell was produced by using the obtained positive electrode and metallic lithium as a counter electrode.
• a 15 ⁇ mm olefin fiber non-woven fabric was used as a separator for electrically separating these.
• the battery performance of the produced lithium-ion secondary battery was evaluated by the following method.
• ⁇ DC resistance> A current of 0.2, 0.4, 0.6, 0.8, 1.0 mmA was applied to a ⁇ 13 mm ⁇ 75 ⁇ m electrode manufactured in the same manner as the above positive electrode, and the voltage after 10 seconds was read. The resistance value was calculated from Ohm's law.
• ⁇ Equivalent to a lithium secondary battery using PVDF as a positive electrode binder
• ⁇ Compared with a lithium secondary battery using PVDF as a positive electrode binder, the high temperature storage characteristics are lower, and the difference is within 5%.
• X Compared with a lithium secondary battery using PVDF as a binder for a positive electrode, the high temperature storage characteristic is low, and the difference is more than 5% and within 15%.
• Example 2 ⁇ Preparation of polyvinyl alcohol (PVA)> As PVA, PVA (B-24) manufactured by Denka Co., Ltd. was used. Table 1 shows the average degree of polymerization and saponification of PVA.
• reaction rate and composition ratio For the obtained composition, the reaction rate of each raw material and the composition ratio of each component were calculated.
• the reaction rate of polyvinyl alcohol was determined by the following method. First, the concentration of PVA in the raw material solution was determined by the absorbance. Next, 50 g of the polymerization reaction solution obtained by the polymerization reaction was centrifuged at 3000 G for 30 minutes to obtain a supernatant. The absorbance in the supernatant was measured and the PVA concentration was measured. The reaction rate of PVA was determined by ⁇ 1- (concentration of PVA in the supernatant) / (concentration of PVA at the time of preparation) ⁇ ⁇ 100. The reaction rate of PVA was 93%.
• the reaction rate of the first monomer and the cross-linking agent was determined by the following method. After completion of the polymerization, methanol was precipitated, and the dried product was dissolved in heavy DMSO, and 1 H-NMR was measured. The composition of each component was calculated from the intensity of the signal corresponding to PVA, the first monomer, and the cross-linking agent in the obtained spectrum with PVA as a reference. Signals derived from PVA at 1 to 1.7 ppm, PAN and vinyl acetate at 1.7 to 2.3 ppm, PAN at 3 to 3.2 ppm, and a cross-linking agent at 3.5 to 3.7 ppm are observed. The reaction rate was calculated by comparing the composition calculated from NMR with the composition of each component at the time of charging. The reaction rate indicates how much of the charged first monomer and cross-linking agent is contained in the composition. The reaction rate of the first monomer was 98%, and the reaction rate of the cross-linking agent was 100%.
• composition ratio of each component of the composition according to Example 2 was calculated from the reaction rate.
• the content of the polyvinyl alcohol structure is 47.7 parts by mass
• the content of the first monomer unit is 48.2 parts by mass
• the content of the structure derived from the cross-linking agent is 4. It was .2 parts by mass.
• the composition ratio includes a free polymer which is a homopolymer of the first monomer.
• composition was obtained in the same manner as in Example 1 except that the blending amount of acrylonitrile added to PVA was as shown in Table 1.
• the monomer unit represents the monomer from which the monomer unit is derived.
• AN Acrylonitrile
• OEG Oligoethylene glycol diacrylate

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