Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
• • 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
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
  • H01M50/417—Polyolefins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
  • H01M50/42—Acrylic resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/431—Inorganic material
  • H01M50/434—Ceramics
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/443—Particulate material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
  • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
  • H01M50/491—Porosity
• • 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 non-aqueous secondary battery functional layer composition, a non-aqueous secondary battery functional layer, a non-aqueous secondary battery separator, and a non-aqueous secondary battery.
• Non-aqueous secondary batteries such as lithium ion secondary batteries (hereinafter sometimes referred to as "secondary batteries") are characterized by being small, lightweight, high energy density, and capable of repeated charging and discharging. Used for a wide range of purposes.
• Non-aqueous secondary batteries generally include battery members such as a positive electrode, a negative electrode, and a separator that separates the positive electrode from the negative electrode to prevent short-circuiting between the positive electrode and the negative electrode.
• a battery member having a functional layer that imparts desired performance for example, heat resistance, strength, etc.
• a functional layer that imparts desired performance (for example, heat resistance, strength, etc.) to the battery member.
• separators in which a functional layer is formed on a separator substrate
• electrodes in which a functional layer is formed on an electrode substrate in which an electrode mixture layer is provided on a current collector.
• battery components are used as battery components.
• a functional layer capable of improving heat resistance and strength of a battery member a functional layer made of a porous film layer formed by binding non-conductive particles with a binder (binding material) is used.
• the functional layer comprises, for example, a functional layer composition containing non-conductive particles, various polymers that can function as a binder, and a dispersion medium as a base material (separator base material, electrode base material, etc.). and drying the applied functional layer composition.
• a non-aqueous secondary battery functional layer composition (hereinafter, sometimes simply referred to as "functional layer composition") used for forming the functional layer ) is actively being improved.
• an amide group-containing monomer unit, an acid group-containing monomer unit and a hydroxyl group-containing monomer unit are contained, and the amide group-containing monomer unit and the acid group-containing monomer are
• a binder composition has been proposed which contains a water-soluble polymer having a body unit content within a predetermined range, and water.
• Patent Document 2 by using both a water-soluble polymer having a predetermined property and a water-insoluble polymer having a particle size within a predetermined range, vibration drop-off resistance and heat resistance in an electrolytic solution are improved.
• a composition for a non-aqueous secondary battery functional layer has been proposed, which is capable of forming a functional layer for a non-aqueous secondary battery with excellent shrinkability.
• Patent Document 3 discloses a composition for a secondary battery porous membrane containing non-conductive particles and a water-soluble polymer, wherein the water-soluble polymer contains a predetermined monomer unit in a predetermined ratio, and a predetermined
• a composition for a secondary battery porous film has been proposed in which the storage elastic modulus of the water-soluble polymer under conditions is a predetermined value or more. According to this composition for secondary battery porous film, it is possible to produce a porous film that has a small residual water content, can be easily applied, and can improve battery performance such as high-temperature cycle characteristics.
• the above-described conventional functional layer composition has the following properties: There was room for further improvement.
• the present invention provides a composition for a non-aqueous secondary battery functional layer that ensures excellent heat shrinkage resistance and can form a functional layer for a non-aqueous secondary battery with a low residual moisture content.
• the present invention provides a functional layer for a non-aqueous secondary battery that ensures excellent heat shrinkage resistance and has a low residual moisture content so that the non-aqueous secondary battery can exhibit excellent high-temperature cycle characteristics.
• An object of the present invention is to provide a separator for non-aqueous secondary batteries having the functional layer for non-aqueous secondary batteries.
• Another object of the present invention is to provide a non-aqueous secondary battery having excellent high-temperature cycle characteristics.
• the inventor of the present invention conducted intensive studies with the aim of solving the above problems. Then, the present inventors have determined that the BET specific surface area of the non-conductive particles is set to a predetermined value or less, and , The parameter P representing the ratio of the filling rate obtained using the non-aqueous secondary battery functional layer composition to the logarithm (Log) of the BET specific surface area of the non-conductive particles is set to a predetermined value or more.
• the present inventors have newly found that a functional layer for a non-aqueous secondary battery can be formed that ensures heat shrinkage resistance and has a low residual moisture content, and has completed the present invention.
• the composition for a non-aqueous secondary battery functional layer of the following [1] to [8], the following [ The functional layer for non-aqueous secondary batteries of [9], the separator for non-aqueous secondary batteries of [10] below, and the non-aqueous secondary battery of [11] below are provided.
• Parameter P Filling rate of non-aqueous secondary battery functional layer composition/Log (BET specific surface area of non-conductive particles) (1)
• the filling rate of the non-aqueous secondary battery functional layer composition is the volume of the sediment layer obtained by centrifugal sedimentation of the non-aqueous secondary battery functional layer composition filled in the test tube.
• the material balance is calculated from the height and obtained based on the following formula (2).
• composition for non-aqueous secondary battery functional layer ⁇ (solid content in composition for non-aqueous secondary battery functional layer (% by volume) x composition for non-aqueous secondary battery functional layer in test tube Volume of object)/volume of deposited layer ⁇ 100% (2)
• the BET specific surface area of the non-conductive particles is set to a predetermined value or less, and the filling rate obtained using the non-aqueous secondary battery functional layer composition with respect to the logarithm of the BET specific surface area of the non-conductive particles If the parameter P representing the ratio is set to a predetermined value or more, it is possible to form a functional layer for a non-aqueous secondary battery in which excellent heat shrinkage resistance is ensured and the remaining water content is small.
• the "water-soluble polymer” refers to a polymer having an insoluble content of less than 1.0% by mass when 0.5 g of the polymer is dissolved in 100 g of water at a temperature of 25°C.
• the "BET specific surface area” refers to the nitrogen adsorption specific surface area measured using the BET method.
• the phrase "comprising a monomer unit” means that "the polymer obtained using the monomer contains a repeating unit derived from the monomer”. means.
• the content of monomer units in the polymer can be measured using nuclear magnetic resonance (NMR) methods such as 1 H-NMR and 13 C-NMR.
• composition for a non-aqueous secondary battery functional layer according to [1] or [2] above, wherein the composition for a non-aqueous secondary battery functional layer has a viscosity of 10 mPa ⁇ s or more and 300 mPa ⁇ s or less.
• the viscosity of the functional layer composition is within the above range, the coatability of the non-aqueous secondary battery functional layer composition can be further improved.
• the "viscosity" of the composition for non-aqueous secondary battery functional layers can be measured using the method described in the Examples of the present specification.
• composition for a non-aqueous secondary battery functional layer according to any one of [1] to [3] above, wherein the water-soluble polymer has a weight average molecular weight of 50,000 or more and 1,000,000 or less. .
• the weight average molecular weight of the water-soluble polymer when the weight average molecular weight of the water-soluble polymer is within the above range, the decrease in the viscosity of the functional layer composition can be suppressed, and the coatability can be further improved. can be further increased in rigidity to further improve the heat shrinkage resistance of the functional layer.
• the "weight average molecular weight" of the water-soluble polymer can be measured using the method described in the Examples of the present specification.
• the composition for a non-aqueous secondary battery functional layer according to any one of [1] to [4] above, wherein the non-conductive particles have a volume average particle size of 0.05 ⁇ m or more and 0.45 ⁇ m or less.
• the volume average particle size of the non-conductive particles means the particle size at which the cumulative volume calculated from the small size side becomes 50% in the particle size distribution (volume basis) measured by the laser diffraction method. (D50).
• the functional layer formed using the composition for a non-aqueous secondary battery functional layer described above ensures excellent heat shrinkage resistance even when the layer is thinned, and the residual moisture content is is small, the secondary battery can exhibit excellent high-temperature cycle characteristics.
• a non-aqueous secondary battery separator comprising the non-aqueous secondary battery functional layer according to [9] above.
• the separator for non-aqueous secondary batteries having the functional layer for non-aqueous secondary batteries described above can exhibit excellent high-temperature cycle characteristics in non-aqueous secondary batteries.
• a non-aqueous secondary battery comprising the non-aqueous secondary battery separator according to [10] above.
• the secondary battery provided with the non-aqueous secondary battery separator described above has excellent high-temperature cycle characteristics.
• a composition for a non-aqueous secondary battery functional layer that ensures excellent heat shrinkage resistance and can form a functional layer for a non-aqueous secondary battery with a small residual moisture content. can do.
• excellent heat shrinkage resistance is ensured, and the residual moisture content is small, so that the non-aqueous secondary battery can exhibit excellent high-temperature cycle characteristics.
• a non-aqueous secondary battery separator comprising a layer and the functional layer for non-aqueous secondary batteries.
• the non-aqueous secondary battery which is excellent in a high temperature cycling characteristic can be provided.
• the composition for a non-aqueous secondary battery functional layer of the present invention is used as a material for forming a non-aqueous secondary battery functional layer.
• the functional layer for non-aqueous secondary batteries of the present invention is formed using the composition for non-aqueous secondary battery functional layers of the present invention.
• the separator for non-aqueous secondary batteries of the present invention comprises at least the functional layer for non-aqueous secondary batteries of the present invention.
• the non-aqueous secondary battery of the present invention includes at least the separator for non-aqueous secondary batteries of the present invention.
• the non-aqueous secondary battery functional layer composition of the present invention contains non-conductive particles and a water-soluble polymer, and optionally non-conductive particles and water-soluble polymers such as particulate polymers and additives. It is a slurry composition using water as a dispersion medium and further containing other components than coalescence.
• the BET specific surface area of the non-conductive particles is 25 m 2 /g or less, and the logarithm (Log) of the BET specific surface area of the non-conductive particles is It is characterized in that a parameter P representing a ratio of filling rates obtained by using the composition for a water-based secondary battery functional layer is equal to or greater than a predetermined value.
• the non-conductive particles have the predetermined properties, and the parameter P is a predetermined value or more, so that excellent heat shrinkage It is possible to form a functional layer for a non-aqueous secondary battery that ensures the properties and has a small amount of residual moisture.
• the functional layer for a non-aqueous secondary battery formed using the composition for a non-aqueous secondary battery functional layer of the present invention the non-aqueous secondary battery can exhibit excellent high-temperature cycle characteristics. .
• the non-conductive particles are particles that do not dissolve in water as a dispersion medium and in a non-aqueous electrolytic solution of a secondary battery, and that maintain their shape even in them.
• the non-conductive particles are electrochemically stable, they stably exist in the functional layer under the usage environment of the secondary battery.
• non-conductive particles for example, various inorganic fine particles and organic fine particles can be used, but usually inorganic fine particles are used.
• the material for the non-conductive particles a material that stably exists in the usage environment of the non-aqueous secondary battery and is electrochemically stable is preferable.
• non-conductive particles from such a viewpoint include aluminum oxide (alumina), aluminum oxide hydrate (boehmite), silicon oxide, magnesium oxide (magnesia), calcium oxide, titanium oxide (titania), Oxide particles such as BaTiO 3 , ZrO, and alumina-silica composite oxides; Nitride particles such as aluminum nitride and boron nitride; Covalent crystal particles such as silicon and diamond; Barium sulfate, calcium fluoride, barium fluoride, etc. Clay fine particles such as talc and montmorillonite; and the like. In addition, these particles may be subjected to element substitution, surface treatment, solid solution treatment, or the like, if necessary. Among these, alumina, boehmite, and barium sulfate are preferable as the non-conductive particles. In addition, the non-conductive particles described above may be used singly or in combination of two or more.
• examples of the shape of the non-conductive particles include elliptical spherical shape, polygonal shape, tetrapod shape, plate shape, scale shape, and the like.
• the aspect ratio of the non-conductive particles is not particularly limited, it is preferably 1.5 or more and 20 or less.
• the BET specific surface area of the non-conductive particles is 25 m 2 /g or less, preferably 23 m 2 /g or less, and more preferably 20 m 2 /g or less. If the BET specific surface area of the non-conductive particles is 25 m 2 /g or less, the residual water content in the functional layer can be reduced.
• the BET specific surface area of the non-conductive particles can be adjusted, for example, by changing the particle size, particle shape, etc. of the non-conductive particles.
• the volume average particle diameter of the non-conductive particles is preferably 0.05 ⁇ m or more, more preferably 0.1 ⁇ m or more, still more preferably 0.15 ⁇ m or more, and 0.45 ⁇ m or less. It is preferably 0.4 ⁇ m or less, more preferably 0.35 ⁇ m or less.
• the volume average particle size of the non-conductive particles is at least the above lower limit, the decrease in ion conductivity can be suppressed, and the cycle characteristics of the secondary battery can be further improved. Further, when the volume average particle size of the non-conductive particles is equal to or less than the above upper limit, excellent heat shrinkage resistance is sufficiently ensured even when the functional layer is thinned and densified.
• the water-soluble polymer is included as a binder in the functional layer composition of the present invention.
• the water-soluble polymer contains at least one monomer unit selected from the group consisting of crosslinkable monomer units, amide group-containing monomer units, and acid group-containing monomer units. preferably.
• the water-soluble polymer optionally contains monomer units other than crosslinkable monomer units, amide group-containing monomer units, and acid group-containing monomer units (hereinafter referred to as "other monomer units ".) may be further contained.
• Crosslinkable monomer unit As the crosslinkable monomer capable of forming a crosslinkable monomer unit, a monomer capable of forming a crosslinked structure when polymerized can be used. Specifically, a monofunctional monomer having a thermally crosslinkable crosslinkable group and one ethylenically unsaturated bond per molecule, and a polyfunctional monomer having two or more ethylenically unsaturated bonds per molecule and a sexual monomer. Examples of thermally crosslinkable crosslinkable groups contained in monofunctional monomers include epoxy groups, N-methylolamide groups, oxetanyl groups, oxazoline groups, and combinations thereof. And the crosslinkable monomer may be hydrophobic or hydrophilic.
• the crosslinkable monomer is "hydrophobic" means that the crosslinkable monomer does not contain a hydrophilic group, and the crosslinkable monomer is "hydrophilic".
• the term means that the crosslinkable monomer contains a hydrophilic group.
• the "hydrophilic group” in the crosslinkable monomer refers to carboxylic acid group, hydroxyl group, sulfonic acid group, phosphoric acid group, epoxy group, thiol group, aldehyde group, amide group, oxetanyl group and oxazoline group.
• Hydrophobic crosslinkable monomers include allyl (meth)acrylate, ethylene di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol
• Polyfunctional (meth)acrylates such as di(meth)acrylate and trimethylolpropane-tri(meth)acrylate; dipropylene glycol diallyl ether, polyglycol diallyl ether, triethylene glycol divinyl ether, hydroquinone diallyl ether, tetraallyloxyethane such as polyfunctional allyl/vinyl ethers; and divinylbenzene.
• Hydrophilic crosslinkable monomers include vinyl glycidyl ether, allyl glycidyl ether, glycidyl methacrylate, N-methylol acrylamide, allyl methacrylamide and the like. Among these, glycidyl methacrylate and N-methylolacrylamide are preferred as crosslinkable monomers. By using glycidyl methacrylate or N-methylolacrylamide, the heat shrinkage resistance of the functional layer can be further improved.
• the crosslinkable monomers may be used singly or in combination of two or more at any ratio.
• the content of the crosslinkable monomer unit in the water-soluble polymer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and 1% by mass or more. is more preferably 10% by mass or less, more preferably 9% by mass or less, and even more preferably 8% by mass or less. If the content of the crosslinkable monomer units is at least the above lower limit, the rigidity of the water-soluble polymer can be increased, and the heat shrinkage resistance of the functional layer can be further improved. Further, when the content of the crosslinkable monomer unit is equal to or less than the above upper limit, the molecular weight of the water-soluble polymer can be lowered, and the coatability of the functional layer composition can be improved.
• amide group-containing monomers capable of forming amide group-containing monomer units include acrylamide, methacrylamide, dimethylacrylamide, and diethylacrylamide.
• an amide group-containing monomer refers to a monomer in which hydrogen or an alkyl group is bonded to the N atom of the amide group.
• acrylamide is preferable as the amide group-containing monomer.
• the amide group-containing monomers may be used singly or in combination of two or more at any ratio.
• the content of the amide group-containing monomer units in the water-soluble polymer is preferably 70% by mass or more, more preferably 73% by mass or more, and even more preferably 80% by mass or more. , is preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 90% by mass or less. If the amide group-containing monomer unit is at least the above lower limit, the rigidity of the water-soluble polymer can be further increased, and the heat shrinkage resistance of the functional layer can be further improved. Moreover, when the content of the amide group-containing monomer unit is equal to or less than the above upper limit, the dispersion stability of the functional layer composition can be improved.
• Acid group-containing monomers capable of forming acid group-containing monomer units include, for example, monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and , a monomer having a hydroxyl group.
• Examples of monomers having a carboxylic acid group include monocarboxylic acids and dicarboxylic acids.
• monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid.
• dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid.
• monomers having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth)allylsulfonic acid, ethyl (meth)acrylate-2-sulfonate, and 2-acrylamido-2-methyl propanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and the like.
• (meth)allyl means allyl and/or methallyl
• (meth)acryl means acryl and/or methacryl
• the monomer having a phosphate group includes, for example, 2-(meth)acryloyloxyethyl phosphate, methyl 2-(meth)acryloyloxyethyl phosphate, ethyl phosphate-(meth)acryloyloxyethyl etc.
• (meth)acryloyl means acryloyl and/or methacryloyl.
• Examples of monomers having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.
• acrylic acid is preferable as the acid group-containing monomer.
• the use of acrylic acid imparts anionic properties to the water-soluble polymer, and interaction between the water-soluble polymer and the surface of the non-conductive particles can suppress moisture adsorption to the functional layer.
• the acid group-containing monomers may be used singly or in combination of two or more at any ratio.
• the content of the acid group-containing monomer unit in the water-soluble polymer is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more. It is preferably 20% by mass or less, more preferably 18% by mass or less, and even more preferably 15% by mass or less. If the content of the acid group-containing monomer unit is at least the above lower limit, the interaction between the water-soluble polymer and the non-conductive particles is further improved, so that the amount of water adsorbed to the functional layer is further reduced. In addition, the amount of residual moisture in the functional layer can be further reduced, and thixotropy is imparted to the composition for the functional layer, so that the coatability of the composition for the functional layer can be further improved. Moreover, when the content of the acid group-containing monomer units is equal to or less than the above upper limit, the dispersion stability and coatability of the functional layer composition are further improved.
• Other monomers that can form other monomer units that can be contained in the water-soluble polymer include the above-mentioned crosslinkable monomers, amide group-containing monomers, and acid group-containing monomers. It is not particularly limited as long as it can be polymerized.
• the content of other monomer units contained in the water-soluble polymer is preferably less than 10% by mass, more preferably less than 5% by mass, and further preferably less than 1% by mass. 0% by weight is particularly preferred.
• the water-soluble polymer preferably has a weight average molecular weight (Mw) of 50,000 or more, more preferably 100,000 or more, even more preferably 200,000 or more. It is preferably 000,000 or less, more preferably 900,000 or less, and even more preferably 700,000 or less.
• Mw weight average molecular weight
• the weight-average molecular weight (Mw) of the water-soluble polymer is at least the above lower limit, the water-soluble polymer can be made more rigid, and the heat shrinkage resistance of the functional layer can be further improved.
• the weight average molecular weight (Mw) of the water-soluble polymer is equal to or less than the above upper limit, the coatability of the functional layer composition is further improved.
• the weight average molecular weight of the water-soluble polymer is not particularly limited. can be controlled by adjusting the blending amounts of the polymerization aid, the polymerization initiator, and the like.
• the content of the water-soluble polymer is preferably 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the non-conductive particles. If the content of the water-soluble polymer is within the above range, the heat shrinkage resistance of the functional layer can be further improved.
• the water-soluble polymer can be produced by polymerizing a monomer composition containing the monomers described above in an aqueous solvent such as water. At this time, the content ratio of each monomer in the monomer composition can be determined according to the content ratio of each repeating unit (monomer unit) in the water-soluble polymer.
• the polymerization mode is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method can be used.
• any reaction such as ionic polymerization, radical polymerization, and living radical polymerization can be used.
• additives such as emulsifiers, dispersants, polymerization initiators and polymerization aids can be used for polymerization.
• the amount of these additives used can also be the amount generally used.
• Polymerization conditions can be appropriately adjusted depending on the polymerization method, the type of polymerization initiator, and the like.
• the particulate polymer that the functional layer composition of the present invention may optionally contain is a water-insoluble polymer.
• the particulate polymer is dispersed in the functional layer composition while maintaining its particle shape, and functions as a binder together with the water-soluble polymer described above.
• the redispersibility of the non-conductive particles is further improved, and the flexibility of the functional layer formed using the composition for the functional layer is improved. can enhance sexuality.
• a polymer being "water-insoluble" means that the insoluble content is 90% by mass or more when 0.5 g of the polymer is dissolved in 100 g of water at 25°C. say.
• the particulate polymer is not particularly limited, and any known particulate polymer that can be used as a binder when forming the functional layer can be used.
• the particulate polymer is not particularly limited, and may be a conjugated diene polymer, a fluoropolymer, an acrylic polymer, etc. Among them, an acrylic polymer is preferable.
• One type of these particulate polymers may be used alone, or two or more types may be used in combination.
• the conjugated diene-based polymer that can be preferably used as the particulate polymer is a polymer containing conjugated diene monomer units.
• Specific examples of the conjugated diene-based polymer are not particularly limited. Examples include polymers, butadiene rubber (BR), acrylic rubber (NBR) (copolymers containing acrylonitrile units and butadiene units), and hydrides thereof.
• a fluorine-based polymer that can be preferably used as the particulate polymer is a polymer containing a fluorine-containing monomer unit.
• the fluorine-based polymer may be a homopolymer or copolymer of one or more fluorine-containing monomers, or a monomer containing one or more fluorine-containing monomers and a fluorine-free monomer (hereinafter referred to as , referred to as "fluorine-free monomer").
• the proportion of fluorine-containing monomer units in the fluoropolymer is usually 70% by mass or more, preferably 80% by mass or more, when the total monomer units in the fluoropolymer are 100% by mass. be.
• the ratio of fluorine-free monomer units in the fluoropolymer is usually 30% by mass or less, preferably 20% by mass or less, when the total monomer units in the fluoropolymer are 100% by mass. is.
• fluorine-containing monomers capable of forming fluorine-containing monomer units include vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, vinyl chloride trifluoride, vinyl fluoride, and perfluoroalkyl vinyl ether. be done. Among these, vinylidene fluoride is preferable as the fluorine-containing monomer.
• fluorine-free monomers capable of forming fluorine-free monomer units include fluorine-free monomers copolymerizable with fluorine-containing monomers, such as ethylene, propylene, and 1-butene.
• Aromatic vinyl compounds such as styrene, ⁇ -methylstyrene, pt-butylstyrene, vinyltoluene, and chlorostyrene;
• Unsaturated nitrile compounds such as (meth)acrylonitrile; Methyl (meth)acrylate, ( (Meth)acrylate compounds such as butyl acrylate and 2-ethylhexyl (meth)acrylate;
• Vinyl compounds containing carboxyl groups such as (meth)acrylic acid, itaconic acid, fumaric acid, crotonic acid and maleic acid;
• an acrylic polymer that can be preferably used as the particulate polymer is a polymer containing a (meth)acrylic acid ester monomer unit.
• the (meth)acrylic acid ester monomer capable of forming the (meth)acrylic acid ester monomer unit includes methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, 2 - (meth)acrylic acid alkyl esters such as ethylhexyl acrylate can be used.
• the acrylic polymer is selected from the group consisting of (meth)acrylonitrile monomer units, acid group-containing monomer units and crosslinkable monomer units in addition to (meth)acrylic acid ester monomer units. It preferably contains at least one type of monomer unit, and more preferably contains a (meth)acrylotlyl monomer unit, an acid group-containing monomer unit and a crosslinkable monomer unit.
• the acid group-containing monomer capable of forming the acid group-containing monomer unit and the crosslinkable monomer capable of forming the crosslinkable monomer unit the same monomer as the water-soluble polymer described above can be used. can be used.
• "(meth)acrylonitrile” means acrylonitrile and/or methacrylonitrile.
• the particulate polymer preferably has a volume average particle diameter of 0.05 ⁇ m or more and 1.0 ⁇ m or less.
• the volume average particle size of the particulate polymer means the particle size at which the cumulative volume calculated from the small size side becomes 50% in the particle size distribution (volume basis) measured by the laser diffraction method. (D50).
• the glass transition temperature (Tg) of the particulate polymer is preferably less than 20°C. If the glass transition temperature of the particulate polymer is less than 20°C, both the flexibility and the binding property of the functional layer can be sufficiently improved. ” can be measured by differential scanning calorimetry in accordance with JIS K6240.
• the amount of the particulate polymer that can be contained in the functional layer composition of the present invention is preferably 0.1 parts by mass or more, and 0.5 parts by mass or more per 100 parts by mass of the non-conductive particles. more preferably 1.0 parts by mass or more, preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less .
• the content of the particulate polymer is at least the above lower limit, it is possible to ensure a sufficient binding force and prevent the non-conductive particles from falling off (powdering) from the functional layer.
• the content of the particulate polymer is set to the above upper limit or less, sufficient porosity of the functional layer can be ensured, and deterioration of the output characteristics of the secondary battery can be suppressed.
• the particulate polymer can be produced by polymerizing a monomer composition containing monomers used for polymerizing the particulate polymer in an aqueous solvent such as water. At this time, the content ratio of each monomer in the monomer composition can be determined according to the content ratio of each repeating unit (monomer unit) in the particulate polymer.
• the polymerization mode is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method can be used.
• As the polymerization reaction any reaction such as ionic polymerization, radical polymerization, and living radical polymerization can be used.
• additives such as emulsifiers, dispersants, polymerization initiators and polymerization aids can be used for polymerization.
• the amount of these additives used can also be the amount generally used.
• Polymerization conditions can be appropriately adjusted depending on the polymerization method, the type of polymerization initiator, and the like.
• Additives that may optionally be included in the functional layer composition of the present invention are not particularly limited as long as they do not affect the battery reaction, and known additives can be used.
• An additive may be used individually by 1 type, and may be used in combination of 2 or more types.
• Examples of additives include known additives such as surfactants and dispersants.
• Surfactants include, but are not limited to, ethylene oxide/propylene oxide surfactants (hereinafter also referred to as "EO/PO surfactants"), fluorine surfactants, and silicone surfactants. etc. can be used. Among them, EO/PO-based surfactants and fluorine-based surfactants are preferably used, and EO/PO-based surfactants are more preferably used. Specific examples of EO/PO surfactants include polyoxyalkylene glycol surfactants. Specific examples of fluorine-based surfactants include fluorine alkyl esters. Specific examples of silicone-based surfactants include dimethylpolysiloxane. Among these surfactants, EO/PO-based surfactants are preferable.
• the content of the surfactant in the functional layer composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, per 100 parts by mass of the non-conductive particles. It is preferably 1.0 parts by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less. If the content of the surfactant is at least the above lower limit, the coatability of the functional layer composition can be further improved. Moreover, if the content of the surfactant is equal to or less than the above upper limit, the heat shrinkage resistance of the functional layer can be further improved.
• the dispersant is not particularly limited, and for example, an acrylic acid/sulfonic acid-based monomer copolymer, a special polyacrylate sodium salt, a special polyacrylate ammonium salt, or the like can be used.
• the content of the dispersant in the functional layer composition is preferably 5 parts by mass or less, more preferably 3 parts by mass or less per 100 parts by mass of the non-conductive particles.
• the content of the dispersant is 5 parts by mass or less, the residual water content in the functional layer can be further reduced, and the heat shrinkage resistance of the functional layer can be further improved.
• the non-aqueous secondary battery functional layer composition of the present invention contains water as a dispersion medium.
• the non-aqueous secondary battery functional layer composition may contain a small amount of a medium other than water, such as an organic solvent, as a dispersion medium.
• the non-aqueous secondary battery functional layer composition of the present invention is not particularly limited, and the above-described non-conductive particles, a water-soluble polymer, and any particulate polymer used as necessary, an interface It can be obtained by mixing an active agent, a dispersant, etc. in the presence of water as a dispersion medium.
• the mixing method and mixing order of the above-described components are not particularly limited, but it is preferable to use a disperser as a mixing device for mixing in order to efficiently disperse each component.
• the disperser is preferably a device capable of uniformly dispersing and mixing the above components. Dispersers include ball mills, sand mills, bead mills, pigment dispersers, crushers, ultrasonic dispersers, homogenizers and planetary mixers.
• the functional layer composition of the present invention preferably has a viscosity of 10 mPa ⁇ s or more, more preferably 30 mPa ⁇ s or more, preferably 300 mPa ⁇ s or less, and preferably 200 mPa ⁇ s or less. It is more preferable to have If the viscosity of the functional layer composition is within the above range, the coatability of the functional layer composition is further improved.
• the composition for the functional layer of the present invention is the ratio of the filling rate obtained using the composition for the functional layer to the logarithm (Log) of the BET specific surface area of the non-conductive particles contained in the composition for the functional layer. is 35 or more, preferably 35.5 or more, and preferably 36 or more. If the parameter P is 35 or more, excellent heat shrinkage resistance can be secured and the residual moisture content in the functional layer can be reduced even when the functional layer is thinned and densified.
• Parameter P Filling ratio of composition for non-aqueous secondary battery functional layer/Log (BET specific surface area of non-conductive particles) (1)
• the filling rate of the non-aqueous secondary battery functional layer composition is the deposit obtained by centrifugal sedimentation of the non-aqueous secondary battery functional layer composition filled in the test tube. The mass balance is calculated from the height of the layer and obtained based on the following formula (2).
• Filling rate (%) of composition for non-aqueous secondary battery functional layer ⁇ (solid content in composition for non-aqueous secondary battery functional layer (% by volume) x composition for non-aqueous secondary battery functional layer in test tube Volume of object)/volume of deposited layer ⁇ 100% (2)
• the non-aqueous secondary battery functional layer of the present invention is formed from the non-aqueous secondary battery functional layer composition described above. After coating to form a coating film, it can be formed by drying the formed coating film.
• the functional layer for a non-aqueous secondary battery of the present invention is made of the dried functional layer composition described above, and usually contains the predetermined non-conductive particles described above and a water-soluble polymer. Further, since the functional layer for a non-aqueous secondary battery of the present invention is formed using the functional layer composition described above, it exhibits excellent heat shrinkage resistance and has a small residual moisture content in the functional layer. . Therefore, by using the functional layer for a non-aqueous secondary battery of the present invention, it is possible to exhibit excellent high-temperature cycle characteristics in the non-aqueous secondary battery.
• the substrate to which the functional layer composition is applied is not particularly limited, and for example, a separator substrate or an electrode substrate can be used as the substrate.
• the separator substrate is not particularly limited, but includes known separator substrates such as organic separator substrates.
• the organic separator base material is a porous member made of an organic material.
• organic separator substrates include polyolefin resins such as polyethylene and polypropylene, microporous membranes and nonwoven fabrics containing aromatic polyamide resins, etc. Among them, polyethylene microporous membranes and nonwoven fabrics are preferable because of their excellent strength.
• the thickness of the separator base material can be any thickness, preferably 5 ⁇ m or more and 30 ⁇ m or less, more preferably 5 ⁇ m or more and 20 ⁇ m or less, and still more preferably 5 ⁇ m or more and 18 ⁇ m or less.
• the thickness of the separator base material is 5 ⁇ m or more. Moreover, if the thickness of the separator base material is 30 ⁇ m or less, the increase in the heat shrinkage force of the separator base material can be suppressed, and the heat shrinkage resistance can be enhanced.
• the electrode base material (positive electrode base material and negative electrode base material) is not particularly limited, but includes an electrode base material in which an electrode mixture layer is formed on a current collector.
• the current collector, the electrode active material (positive electrode active material, negative electrode active material) in the electrode mixture layer, and the binder for the electrode mixture layer (binder for the positive electrode mixture layer, binder for the negative electrode mixture layer) Adhesion material), and a known method for forming an electrode mixture layer on a current collector can be used, for example, described in JP-A-2013-145763 and WO 2015/129408. can use things.
• Non-aqueous secondary battery functional layer composition of the present invention is applied to the surface of a separator base material or an electrode base material (in the case of an electrode base material, the surface of the electrode mixture layer side; the same shall apply hereinafter), and then dried.
• Method 1 A method of immersing a separator base material or an electrode base material in the non-aqueous secondary battery functional layer composition of the present invention and then drying it; 3) The non-aqueous secondary battery functional layer composition of the present invention is applied on a release substrate and dried to produce a functional layer, and the resulting functional layer is applied to the surface of a separator substrate or an electrode substrate.
• a method of transcription Among these methods, the method 1) is particularly preferable because the layer thickness of the functional layer can be easily controlled.
• the method 1) comprises a step of applying the composition for the functional layer onto the substrate (coating step), and drying the composition for the functional layer coated on the substrate to form the functional layer. (functional layer forming step).
• the method of applying the functional layer composition onto the substrate is not particularly limited, and examples thereof include doctor blade method, reverse roll method, direct roll method, gravure method, extrusion method, and brush coating. methods such as law.
• the method for drying the functional layer composition on the substrate is not particularly limited, and known methods can be used. For example, drying with hot air, hot air, low humidity air, and vacuum drying , and a drying method by irradiation with infrared rays, electron beams, or the like.
• the drying conditions are not particularly limited, but the drying temperature is preferably 50 to 150° C., and the drying time is preferably 3 to 30 minutes.
• the thickness of the functional layer formed as described above is preferably 0.1 ⁇ m or more, preferably 10 ⁇ m or less, and 5 ⁇ m or less, from the viewpoint of sufficiently ensuring the heat shrinkage resistance of the functional layer. is more preferably 3 ⁇ m or less, and more preferably 3 ⁇ m or less
• the non-aqueous secondary battery separator of the present invention (hereinafter also referred to as "secondary battery separator") is a non-aqueous secondary battery functional layer formed using the functional layer composition of the present invention described above.
• the non-aqueous secondary battery separator of the present invention comprises the above-described non-aqueous secondary battery functional layer on at least one surface of the separator substrate.
• the separator base material used for the secondary battery separator is not particularly limited, and the separator base material exemplified as the base material for applying the functional layer composition described above can be used.
• the method for producing the secondary battery separator is not particularly limited, and the separator can be produced according to the method described in the above section of the method for forming a functional layer for a non-aqueous secondary battery.
• the secondary battery of the present invention comprises the non-aqueous secondary battery separator of the present invention described above. More specifically, the non-aqueous secondary battery of the present invention comprises a positive electrode, a negative electrode, a separator, and an electrolytic solution, and the separator is the non-aqueous secondary battery separator of the present invention described above. And since the secondary battery of this invention is equipped with the separator for non-aqueous secondary batteries, it is excellent in high temperature cycling characteristics.
• the separator used in the secondary battery of the present invention is the separator of the present invention described above.
• the positive electrode and the negative electrode are not particularly limited, and known positive and negative electrodes can be used.
• an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used.
• a supporting electrolyte for example, a lithium salt is used in a lithium ion secondary battery.
• lithium salts include LiPF 6 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAlCl 4 , LiClO 4 , CF 3 SO 3 Li, C 4 F 9 SO 3 Li, CF 3 COOLi, (CF 3 CO) 2 NLi. , (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) NLi and the like.
• LiPF 6 , LiClO 4 and CF 3 SO 3 Li are preferable because they are easily dissolved in a solvent and exhibit a high degree of dissociation.
• one electrolyte may be used alone, or two or more electrolytes may be used in combination at an arbitrary ratio.
• lithium ion conductivity tends to increase as a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted depending on the type of supporting electrolyte.
• the organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte.
• carbonates are preferable because they have a high dielectric constant and a wide stable potential region.
• the lower the viscosity of the solvent used the higher the lithium ion conductivity tends to be, so the lithium ion conductivity can be adjusted by the type of solvent.
• concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate. Further, known additives may be added to the electrolytic solution.
• the non-aqueous secondary battery of the present invention for example, the positive electrode and the negative electrode are superimposed with a separator interposed therebetween, and if necessary, this is rolled or folded according to the shape of the battery, placed in a battery container, and electrolyzed in the battery container. It can be manufactured by injecting a liquid and sealing.
• the separator As the separator, the non-aqueous secondary battery separator of the present invention is used.
• a fuse an overcurrent prevention element such as a PTC element, an expanded metal, a lead plate, etc. may be provided as necessary.
• the shape of the secondary battery may be, for example, coin-shaped, button-shaped, sheet-shaped, cylindrical, rectangular, or flat.
• the weight average molecular weight of the water-soluble polymer, the volume average particle diameter of the non-conductive particles, the BET specific surface area of the non-conductive particles, the filling rate of the functional layer composition, the functional layer composition The viscosity, parameter P, dispersion stability of the functional layer composition, coatability of the functional layer composition, heat shrinkage resistance of the functional layer, water content of the functional layer, and high-temperature cycle characteristics of the secondary battery were determined by the following methods. was measured and evaluated.
• ⁇ Weight average molecular weight of water-soluble polymer> The aqueous solutions containing the water-soluble polymers produced in Examples and Comparative Examples were diluted to adjust the concentration to 0.05%. Then, it was filtered through a 0.45 ⁇ m membrane filter made of PTFE to obtain a sample. This sample was analyzed by gel permeation chromatography under the following conditions to determine the weight average molecular weight of the water-soluble polymer.
• Apparatus Gel permeation chromatograph GPC (manufactured by Agilent, product name "1260 Infinity II HPLC") Detector: Differential refractive index detector RI (manufactured by Agilent, product name "1260 Infinity II RI detector”) Column: 2 TSKgel GMPWXL ( ⁇ 7.8 mm ⁇ 30 cm, manufactured by Tosoh) Solvent: 0.1 M Tris buffer (pH 9, 0.1 M potassium chloride added) Flow rate: 0.7 mL/min Column temperature: 40°C Injection volume: 0.2 mL Standard sample: Tosoh and Sigma-Aldrich, monodisperse polyethylene oxide (PEO)
• PEO polyethylene oxide
• ⁇ Volume average particle size of non-conductive particles> In accordance with JIS Z8825, in the particle size distribution (volume basis) of the non-conductive particles measured by the laser diffraction method, the particle diameter (D50) at which the cumulative volume calculated from the small diameter side becomes 50%, the non-conductive particles. A volume average particle diameter was used.
• BET specific surface area of non-conductive particles was determined using a wet specific surface area measuring device (“Flowsorb III 2305” manufactured by Shimadzu Corporation).
• the functional layer composition filled in the test tube was centrifuged at 4000 rpm for 3 hours and sedimented to obtain a sediment layer.
• the material balance was calculated from the height of this deposited layer, and the filling rate of the functional layer composition was obtained according to the following formula.
• composition for functional layer ⁇ (solid content (% by volume) in composition for functional layer x volume of composition for functional layer in test tube)/volume of deposited layer ⁇ x 100%
• the solid content (% by volume) in the composition for functional layer was calculated from the solid content (% by mass) using the specific gravity of each solid content contained in the composition for functional layer.
• the specific gravity of each solid component is shown below (unit: kg/m 3 ).
• Parameter P Filling rate of functional layer composition/Log (BET specific surface area of non-conductive particles)
• ⁇ Dispersion stability of functional layer composition > 1 kg of functional layer compositions prepared in Examples and Comparative Examples were placed in a 1 L plastic bottle and allowed to stand for 10 days. The standing plastic bottle was stirred for 30 minutes together with the plastic bottle using a mix rotor. After stirring, the functional layer composition in the plastic bottle was sampled from within 1 cm from the top, and then the sampled sample was placed in an aluminum dish and weighed (mass: W0 [g]). Then, the aluminum dish containing the sampling sample was placed on a hot plate heated to 130° C. for 30 minutes to dry, and then weighed (mass: W1 [g]). Then, the solid content of the sampled supernatant was measured according to the following formula (I).
• composition for functional layer The functional layers of the secondary battery separators (separators having a functional layer on one side) produced in Examples and Comparative Examples were visually observed for appearance and evaluated according to the following criteria. The wider the range in which aggregates, streaks, and/or repellants are not observed, the more excellent the coatability of the functional layer composition.
• B 10 cm ⁇ 10 cm or more and less than 30 cm ⁇ 30 cm in the range where no aggregates, streaks, and/or repelling are observed
• C Thermal shrinkage rate is 20% or more
• ⁇ Moisture content of functional layer> The secondary battery separators produced in Examples and Comparative Examples were cut into a size of 10 cm in width ⁇ 10 cm in length to obtain a test piece. This test piece was allowed to stand at a temperature of 25° C. and a dew point temperature of ⁇ 60° C. for 24 hours. Then, using a coulometric moisture meter, the water content of the test piece was measured by the Karl Fischer method (JIS K-0068 (2001) moisture vaporization method, vaporization temperature 150°C). The obtained water content was taken as the water content of the functional layer, and evaluated according to the following criteria. A lower water content indicates a lower residual water content in the functional layer.
• Capacity retention rate ⁇ C is 75% or more
• B Capacity retention rate ⁇ C is 60% or more and less than 75%
• C Capacity retention rate ⁇ C is less than 60%
• Example 1 ⁇ Preparation of aqueous solution containing water-soluble polymer> 1267 g of deionized water and 34 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added to a 2 L flask equipped with a septum, heated to a temperature of 40° C., and nitrogen gas was introduced into the flask at a flow rate of 100 mL/min. replaced. Next, 224 g (86.0%) of acrylamide as an amide group-containing monomer, 23 g (9.0%) of acrylic acid as an acid group-containing monomer, and 13 g of glycidyl methacrylate as a crosslinkable monomer.
• composition for secondary battery functional layer ⁇ Preparation of composition for secondary battery functional layer> Boehmite A particles (manufactured by Nabaltec, product name “ACTILOX 200SM”, volume average particle diameter: 0.3 ⁇ m, BET specific surface area: 17 m 2 /g as non-conductive particles, and ammonium polyacrylate (Toagosei Co., Ltd.) as a dispersant (product name “Aron A30SL”). 100 parts of non-conductive particles, 1.0 part of a dispersing agent, and ion-exchanged water were mixed and treated with a bead mill (manufactured by Ashizawa Finetech, product name: "LMZ015") for 1 hour to obtain a dispersion.
• a bead mill manufactured by Ashizawa Finetech, product name: "LMZ015"
• aqueous solution containing the water-soluble polymer obtained as described above and a polyoxyalkylene glycol-based surfactant as a surfactant was mixed to prepare a functional layer composition having a solid concentration of 40%.
• a functional layer composition having a solid concentration of 40%.
• separator base material a separator base material made of polyethylene (manufactured by Asahi Kasei Corporation, product name “ND412”, thickness: 12 ⁇ m) was prepared.
• the functional layer composition prepared above was applied using a gravure coater at a speed of 10 m/min, and then dried in a drying oven at 50°C.
• a separator with a functional layer was obtained.
• the heat shrinkage resistance and moisture content of the functional layer were evaluated. Table 1 shows the results.
• the mixture was cooled to terminate the polymerization reaction to obtain a mixture containing a particulate binder (styrene-butadiene copolymer).
• a particulate binder styrene-butadiene copolymer
• pH 8
• unreacted monomers were removed by heating under reduced pressure distillation.
• the mixture was cooled to 30° C. or less to obtain an aqueous dispersion containing the negative electrode binder.
• a slurry composition for a negative electrode mixture layer was prepared.
• the negative electrode mixture layer slurry composition was applied to the surface of a 15 ⁇ m-thick copper foil as a current collector with a comma coater in an amount of 11 ⁇ 0.5 mg/cm 2 .
• the copper foil coated with the slurry composition for the negative electrode mixture layer is conveyed at a speed of 400 mm / min in an oven at a temperature of 80 ° C. for 2 minutes and further in an oven at a temperature of 110 ° C. for 2 minutes.
• the slurry composition on the copper foil was dried to obtain a negative electrode raw sheet in which a negative electrode mixture layer was formed on a current collector.
• the negative electrode mixture layer side of the negative electrode raw fabric thus prepared was roll-pressed under conditions of a temperature of 25 ⁇ 3° C. and a linear pressure of 11 t (tons), resulting in a negative electrode having a negative electrode mixture layer density of 1.60 g/cm 3 . got
• a planetary mixer was charged with 96 parts of a Co—Ni—Mn lithium composite oxide-based active material NMC532 (LiNi 0.5 Mn 0.3 Co 0.2 O 2 ) as a positive electrode active material, and acetylene as a conductive material.
• 2 parts of black manufactured by Denka Co., Ltd., product name "HS-100”
• 2 parts of polyvinylidene fluoride manufactured by Kureha Chemical Co., Ltd., product name "KF-1100" as a binder are added, and a dispersion medium is added.
• NMP N-methyl-2-pyrrolidone
• the slurry composition on the aluminum foil is dried, and the current collector A positive electrode raw sheet having a positive electrode mixture layer formed thereon was obtained.
• the positive electrode material layer side of the positive electrode raw material prepared was roll-pressed under the conditions of a linear pressure of 14 t (tons) in an environment of a temperature of 25 ⁇ 3 ° C., and a positive electrode with a positive electrode material layer density of 3.20 g / cm 3 got
• Example 2 In the preparation of the aqueous solution containing the water-soluble polymer of Example 1, the acrylamide, acrylic acid and glycidyl used were adjusted so that the content of various monomer units in the resulting water-soluble polymer was the proportion shown in Table 1. The amount of methacrylate was changed. Otherwise, in the same manner as in Example 1, an aqueous solution containing water-soluble polymer B (Example 2) and an aqueous solution containing water-soluble polymer C (Example 3) were prepared.
• Example 3 the aqueous solution containing the water-soluble polymer A
• Example 2 the aqueous solution containing the water-soluble polymer B
• Example 3 the aqueous solution containing the aqueous solution polymer C
• a functional layer composition, a secondary battery separator, a negative electrode, a positive electrode, and a lithium ion secondary battery were prepared and produced.
• Table 1 shows the results.
• Example 4 In the preparation of the aqueous solution containing the water-soluble polymer of Example 1, 13 g (5.0%) of N-methylolacrylamide was used instead of glycidyl methacrylate as the crosslinkable monomer, and the water-soluble polymer D was used. An aqueous solution was prepared. Then, the functional layer composition, the secondary battery separator, the negative electrode, the A positive electrode and a secondary battery were prepared and produced. Various measurements and evaluations were performed in the same manner as in Example 1. Table 1 shows the results.
• Examples 5-7 In the preparation of the functional layer composition of Example 1, instead of boehmite A particles as non-conductive particles, alumina A particles (Example 5: manufactured by Sumitomo Chemical Co., Ltd., product name “AKP-20”, volume Average particle diameter: 0.42 ⁇ m, BET specific surface area: 4.6 m 2 /g), and in Example 6, alumina B particles (manufactured by Sumitomo Chemical Co., Ltd., product name “AKP-53”, volume average particle diameter: 0.17 ⁇ m, BET specific surface area: 13.7 m 2 /g), barium sulfate particles in Example 7 (manufactured by Takehara Chemical Co., Ltd., product name “TS-2”, volume average particle size: 0.36 ⁇ m, BET specific surface area: 7.5 m 2 /g) was used.
• alumina A particles Example 5: manufactured by Sumitomo Chemical Co., Ltd., product name “AKP-20”, volume Average particle diameter: 0.42 ⁇ m,
• Example 1 a functional layer composition, a secondary battery separator, a negative electrode, a positive electrode, and a secondary battery were prepared and produced. Various measurements and evaluations were performed in the same manner as in Example 1. Table 1 shows the results.
• Example 1 a functional layer composition, a secondary battery separator, a negative electrode, a positive electrode, and a secondary battery were prepared and produced. Various measurements and evaluations were performed in the same manner as in Example 1. Table 1 shows the results.
• AAm indicates an acrylamide unit
• AA indicates an acrylic acid unit
• GMA indicates a glycidyl methacrylate unit
• NMA denotes N-methylolacrylamide units
• PAA indicates ammonium polyacrylate
• EO PO indicates a polyoxyalkylene glycol-based surfactant
• the composition for secondary battery functional layers which is excellent in heat shrinkage resistance, and forms the functional layer for non-aqueous secondary batteries with a small water content can be provided.
• a functional layer for a secondary battery and a separator for a secondary battery which are capable of exhibiting excellent high-temperature cycle characteristics in the secondary battery.
• the secondary battery which is excellent in a high temperature cycling characteristic can be provided.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Materials Engineering (AREA)
• Ceramic Engineering (AREA)
• Composite Materials (AREA)
• Manufacturing & Machinery (AREA)
• Cell Separators (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=85782391

Family Applications (1)

Country Status (6)

Families Citing this family (1)

Citations (7)

Family Cites Families (2)

• 2022
  • 2022-09-09 US US18/687,296 patent/US20240405369A1/en active Pending
  • 2022-09-09 EP EP22875782.9A patent/EP4411966A4/en active Pending
  • 2022-09-09 WO PCT/JP2022/033952 patent/WO2023053910A1/ja not_active Ceased
  • 2022-09-09 JP JP2023550527A patent/JPWO2023053910A1/ja active Pending
  • 2022-09-09 KR KR1020247005120A patent/KR20240069710A/ko active Pending
  • 2022-09-09 CN CN202280042610.0A patent/CN117501530A/zh active Pending

Patent Citations (7)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events