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
  • H01M50/411—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
  • 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
• • 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
  • H01M50/406—Moulding; Embossing; Cutting
• • 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
  • H01M50/429—Natural polymers
• • 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
  • H01M50/429—Natural polymers
  • H01M50/4295—Natural cotton, cellulose or wood
• • 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
• • 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
• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to a separator and a manufacturing method thereof, and more particularly to a separator for a non-aqueous electrolyte secondary battery and a manufacturing method thereof.
• Non-aqueous electrolyte secondary batteries are widely used as batteries for personal computers, mobile phones, portable information terminals and the like because of their high energy density.
• Non-aqueous electrolyte secondary batteries represented by these lithium ion secondary batteries have high energy density. If an internal short circuit or external short circuit occurs due to damage to the battery or equipment using the battery, a large current may flow and abnormal heat generation may occur. Therefore, non-aqueous electrolyte secondary batteries are required to prevent heat generation beyond a certain level and ensure high safety. In the case of abnormal heat generation, the separator generally has a shutdown function that blocks the flow of ions between positive and negative electrodes to prevent further heat generation.
• Examples of the separator having a shutdown function include a separator having a porous film made of a material that melts when abnormal heat is generated. That is, in the battery using the separator, when the porous film melts and becomes non-porous during abnormal heat generation, the passage of ions can be blocked and further heat generation can be suppressed.
• a separator having such a shutdown function for example, a polyolefin porous film is used.
• a separator made of a polyolefin porous membrane can block the passage of ions (shutdown) by melting and making it non-porous at about 80 to 180 ° C. during abnormal heat generation of the battery, and can suppress further heat generation. .
• a separator made of a polyolefin porous membrane may cause a short circuit due to direct contact between the positive electrode and the negative electrode due to shrinkage or membrane breakage.
• a separator made of a polyolefin porous film has insufficient shape stability when the temperature is further increased, and abnormal heat generation due to a short circuit may not be suppressed.
• a method of imparting shape stability at high temperature to a separator by laminating a porous film made of a heat-resistant material on a polyolefin porous film has been studied.
• a separator in which a porous film obtained by immersing a regenerated cellulose film in an organic solvent and a polyolefin porous film are laminated is proposed (for example, Patent Document 1). reference.).
• Such a separator can provide a non-aqueous electrolyte secondary battery having excellent shape stability at high temperatures and higher safety, but the load of the non-aqueous electrolyte secondary battery obtained by using the separator There was a problem that the characteristics were insufficient.
• Patent Document 2 discloses a separator in which a porous film containing fine particles and a water-soluble polymer and a polyolefin porous film are laminated as a separator having excellent shape stability at high temperature in addition to shutdown property.
• the separator includes a step of coating a slurry containing a water-soluble polymer, fine particles, and a medium on the polyolefin porous membrane, and a water-soluble polymer and fine particles by removing the medium from the obtained coated film.
• the objective of this invention is providing the separator for non-aqueous-electrolyte secondary batteries excellent in shutdown property and shape stability in high temperature, and the method of manufacturing this separator with sufficient reproducibility.
• the present invention provides the following. ⁇ 1> A separator in which a porous film containing fine particles and a water-soluble polymer and a polyolefin porous film are laminated to each other, The fine particles are substantially composed of fine particles (a) having an average particle size of less than 0.1 ⁇ m and a specific surface area of 50 m 2 / g or more and fine particles (b) having an average particle size of 0.2 ⁇ m or more, The weight ratio of the fine particles (b) to the fine particles (a) is 0.05 to 50, A separator having a weight ratio of fine particles to a water-soluble polymer of 1 to 100.
• ⁇ 2> The separator according to ⁇ 1>, wherein the specific surface area of the fine particles (b) is 20 m 2 / g or less.
• the water-soluble polymer is at least one polymer selected from the group consisting of cellulose ether, polyvinyl alcohol, and sodium alginate.
• the cellulose ether is carboxymethylcellulose.
• the polyolefin porous membrane is a polyethylene porous membrane.
• a step of applying a slurry containing a water-soluble polymer, fine particles and a medium onto the polyolefin porous film, and a porous film containing the water-soluble polymer and the fine particles by removing the medium from the obtained coated film A separator comprising a step of laminating on a polyolefin porous membrane, The fine particles are substantially composed of fine particles (a) having an average particle size of less than 0.1 ⁇ m and a specific surface area of 50 m 2 / g or more and fine particles (b) having an average particle size of 0.2 ⁇ m or more, The weight ratio of the fine particles (b) to the fine particles (a) is 0.05 to 50, The weight ratio of the fine particles to the water-soluble polymer is 1 to 100, And the manufacturing method of the separator whose water-soluble polymer density
• ⁇ 8> The method for producing a separator according to ⁇ 7>, wherein the specific surface area of the fine particles (b) is 20 m 2 / g or less.
• ⁇ 9> The method for producing a separator according to ⁇ 7> or ⁇ 8>, wherein the solid content concentration in the slurry is 6 to 50% by weight.
• ⁇ 10> The method for producing a separator according to any one of ⁇ 7> to ⁇ 9>, wherein the water-soluble polymer is at least one polymer selected from the group consisting of cellulose ether, polyvinyl alcohol, and sodium alginate.
• ⁇ 11> The method for producing a separator according to ⁇ 10>, wherein the cellulose ether is carboxymethylcellulose.
• ⁇ 12> The method for producing a separator according to any one of ⁇ 7> to ⁇ 11>, wherein the polyolefin porous membrane is a polyethylene porous membrane.
• the separator of the present invention includes a porous film (hereinafter sometimes referred to as “A film”) containing a water-soluble polymer and fine particles and a polyolefin porous film (hereinafter sometimes referred to as “B film”).
• the separators are laminated to each other, and a step of applying a slurry containing a water-soluble polymer, fine particles and a medium to a polyolefin porous film (B film) as described later, and drying the medium from the obtained coating film It can be manufactured by a method including a removing step.
• the A film has heat resistance at a high temperature at which shutdown occurs, and imparts a shape stability function to the separator.
• the B film imparts a shutdown function to the separator by melting and becoming non-porous during abnormal heat generation.
• the A film and the B film described above may be stacked on each other and may be three or more layers. For example, the form etc. with which A film
• the A film in the separator will be described.
• the A film is a porous film containing fine particles and a water-soluble polymer.
• water-soluble polymers include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, polymethacrylic acid, etc., cellulose ether, polyvinyl alcohol, sodium alginate are preferred, and cellulose ether is further included.
• cellulose ethers include carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), carboxyethyl cellulose, methyl cellulose, ethyl cellulose, cyanethyl cellulose, oxyethyl cellulose, and the like. Is particularly preferred.
• fine particles in the present invention fine particles made of an inorganic material or an organic material can be used.
• organic materials include homopolymers such as styrene, vinyl ketone, acrylonitrile, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and methyl acrylate, or two or more types of copolymers; Fluororesin such as fluoroethylene, tetrafluoroethylene-6-propylene copolymer, tetrafluoroethylene-ethylene copolymer, polyvinylidene fluoride, melamine resin, urea resin, polyethylene, polypropylene, polymethacrylate, etc. Can be mentioned.
• inorganic materials include calcium carbonate, talc, clay, kaolin, silica, hydrotalcite, diatomaceous earth, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, oxidation Examples include calcium, magnesium oxide, titanium oxide, alumina, mica, zeolite, and glass.
• an inorganic material is preferable, and alumina is more preferable.
• These fine particle materials can be used alone. Two or more materials can be mixed and used.
• the fine particles constituting the A film have an average particle size of less than 0.1 ⁇ m and a specific surface area of 50 m.
• the materials of the fine particles (a) and the fine particles (b) may be the same as each other or different from each other.
• the fine particles (b) having a large particle size serve as a main skeleton in the A film and contribute to the shape stability of the A film at high temperatures.
• the fine particles (a) having a small particle size have an action of appropriately filling the gaps between the fine particles (b) to further increase the mechanical strength of the A film.
• the A film contains both fine particles (a) and fine particles (b).
• fine particles (a) When only one of fine particles (a) and fine particles (b) is used, it has both high air permeability at practical level and shutdown property while maintaining sufficient air permeability (ion permeability). Is difficult.
• the fine particles (a) have an average particle size of less than 0.1 ⁇ m, preferably less than 0.05 ⁇ m, and the specific surface area of the fine particles (a) is 50 m. 2 / G or more, preferably 70 m 2 / G or more.
• the average particle diameter of the fine particles (a) is usually about 0.01 ⁇ m or more.
• the specific surface area of the fine particles (a) is usually 150 m. 2 / G or less.
• the shape of the fine particles (a) include a spherical shape and a bowl shape. Fine particles (a) have an average particle size of less than 0.1 ⁇ m and a specific surface area of 50 m. 2 Unless both of the above are satisfied, the shutdown property (non-porous B film) of the separator becomes insufficient.
• the specific surface area of the fine particles (a) is a value measured by the BET measurement method.
• the fine particles (b) have an average particle size of 0.2 ⁇ m or more, preferably 0.25 ⁇ m or more.
• the specific surface area of the fine particles (b) is not particularly limited, but is preferably 20 m.
• the average particle diameter of the fine particles (b) is usually about 1.0 ⁇ m or less.
• the specific surface area of the fine particles (a) is usually 4.0 m. 2 / G or more.
• the shape of the fine particles (b) include a spherical shape and a bowl shape.
• the average particle size of the fine particles (b) is 25 particles by arbitrarily extracting 25 particles with a scanning electron microscope (SEM) and measuring the particle size (diameter) of each particle. It is a value calculated as an average value of.
• the weight ratio of the fine particles (b) to the fine particles (a) is 0.05 to 50, preferably 0. 1 to 15 and particularly preferably 0.2 to 10. If the weight ratio is less than 0.05, the thermal contraction of the A film cannot be sufficiently suppressed, the shape stability at high temperature becomes insufficient, and if it exceeds 50, the shutdown performance of the separator is impaired.
• fine particles other than the fine particles (a) and the fine particles (b) may be included as long as the effects of the present invention are not significantly impaired.
• the proportion of the content of other fine particles in the A film is preferably 100% by weight or less (including 0% by weight) with respect to the total weight of the fine particles (a) and (b), and is 50% by weight. More preferably (including 0% by weight).
• the thickness of the A film is usually 0.1 ⁇ m or more and 20 ⁇ m or less, preferably 2 ⁇ m or more and 15 ⁇ m or less. If it is too thick, the load characteristics of the battery may be reduced when a non-aqueous electrolyte secondary battery is manufactured.
• the polyolefin porous membrane may be thermally contracted when abnormal heat generation of the battery occurs. There is a possibility that the separator shrinks without being able to resist.
• the thickness of the A film is the total thickness of both surfaces.
• the A film is a porous film, and the pore diameter is preferably 3 ⁇ m or less, more preferably 1 ⁇ m or less, as the diameter of the sphere when the hole is approximated to a sphere. If the average pore size or the pore size exceeds 3 ⁇ m, a short circuit may occur when the carbon powder, which is the main component of the positive electrode or the negative electrode, or a small piece thereof falls off.
• the porosity of the A film is preferably 30 to 90% by volume, more preferably 40 to 85% by volume.
• the B film is a polyolefin porous film and does not dissolve in the electrolyte solution in the non-aqueous electrolyte secondary battery.
• the B film has a molecular weight of 5 ⁇ 10 5 ⁇ 15 ⁇ 10 6 It is preferable to include a high molecular weight component.
• the polyolefin include a homopolymer or a copolymer obtained by polymerizing ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and the like.
• the B film preferably contains polyethylene or polypropylene and has a weight average molecular weight of 1 ⁇ 10 5 It is more preferable to include the above high molecular weight polyethylene, and the weight average molecular weight is 5 ⁇ 10. 5 Even more preferably, the above ultrahigh molecular weight polyethylene is included.
• the porosity of the B film is preferably 20 to 80% by volume, more preferably 30 to 70% by volume. If the porosity is less than 20% by volume, the amount of electrolyte retained may be small, and if it exceeds 80% by volume, non-porous formation at a high temperature that causes shutdown will be insufficient, and current will be generated when abnormal heat generation of the battery occurs. May not be able to be blocked.
• the thickness of the B film is usually 4 to 50 ⁇ m, preferably 5 to 30 ⁇ m. If the thickness is less than 4 ⁇ m, the shutdown may be insufficient, and if it exceeds 50 ⁇ m, the thickness of the entire separator is increased and the electric capacity of the battery may be decreased.
• the pore size of the B film is preferably 3 ⁇ m or less, and more preferably 1 ⁇ m or less.
• the B membrane has a structure having pores connected to the inside thereof, and allows gas and liquid to pass from one surface to the other surface.
• the air permeability of the B film is usually 50 to 400 seconds / 100 cc in terms of Gurley value, and preferably 50 to 300 seconds / 100 cc.
• the production method of the B film is not particularly limited.
• a plasticizer is added to polyolefin to form a film, and then the plasticizer is removed with an appropriate solvent.
• a film made of polyolefin produced by a known method is used, and a structurally weak amorphous portion of the film is selectively stretched to form fine pores. The method of forming is mentioned.
• the B film is formed from an ultrahigh molecular weight polyethylene and a polyolefin containing a low molecular weight polyolefin having a weight average molecular weight of 10,000 or less, it is produced by the following method from the viewpoint of production cost. Is preferred.
• Step of obtaining a composition Step of molding a sheet using the polyolefin resin composition (3) The process of removing an inorganic filler from the sheet
• Step of obtaining a B film by stretching the sheet obtained in step (3) Or a method comprising (1) A step of kneading 100 parts by weight of ultrahigh molecular weight polyethylene, 5 to 200 parts by weight of a low molecular weight polyolefin having a weight average molecular weight of 10,000 or less, and 100 to 400 parts by weight of an inorganic filler to obtain a polyolefin resin composition (2) A step of forming a sheet using the polyolefin resin composition (3) Step of obtaining a stretched sheet by stretching the sheet obtained in step (2) (4) Step of removing the inorganic filler from the stretched sheet obtained in step (3) to obtain a B film It is a method including.
• the A film and B film described above are laminated together to form a separator.
• the separator may include a porous film other than the A film and the B film, for example, a porous film such as an adhesive film and a protective film as long as the object of the present invention is not significantly impaired.
• the total thickness of the separator (the total thickness of the A film + the B film) is usually 5 to 80 ⁇ m, preferably 5 to 50 ⁇ m, and particularly preferably 6 to 35 ⁇ m. If the thickness of the whole separator is less than 5 ⁇ m, the film is likely to break, and if it exceeds 80 ⁇ m, the electric capacity of the battery may be reduced.
• the porosity of the entire separator is usually 30 to 85% by volume, preferably 35 to 80% by volume.
• the air permeability of the separator is preferably 50 to 2000 seconds / 100 cc, more preferably 50 to 1000 seconds / 100 cc. preferable. If the air permeability is 2000 seconds / 100 cc or more, the ion permeability of the separator and the load characteristics of the battery may be lowered.
• the dimension retention rate of the separator at a high temperature at which shutdown occurs is 90% or more, preferably 95% or more.
• the size maintenance ratio of the separator may vary depending on the MD direction and TD direction of the B film. In this case, a smaller value of the dimension maintenance ratio of the B film in the MD direction and the dimension maintenance ratio in the TD direction is set to Use.
• the MD direction refers to the long direction during sheet forming
• the TD direction refers to the width direction during sheet forming. If the dimensional maintenance ratio is less than 90%, a short circuit occurs between the positive and negative electrodes due to thermal contraction of the separator at a high temperature at which shutdown occurs, and as a result, the shutdown function may be insufficient.
• the high temperature at which shutdown occurs is a temperature of 80 to 180 ° C., usually about 130 to 150 ° C.
• the separator of the present invention is a method comprising a step of coating a slurry containing a water-soluble polymer, fine particles and a medium (slurry for forming an A film) on the B film, and a step of removing the medium from the obtained coated film.
• the coating film is a film coated on the B film.
• a film porous film containing a water-soluble polymer and fine particles is obtained, and the A film is laminated on the B film. It is presumed that when the coating film dries, a gap is formed around the fine particles and an A film is generated.
• the slurry may be applied to both sides of the B film, and the A film may be formed on both sides of the B film.
• the slurry in the method of the present invention dissolves or swells a water-soluble polymer in a medium (a liquid in which a water-soluble polymer swells may be used if it can be applied), and further adds fine particles thereto and mixes until uniform. It can be obtained by the method.
• the mixing method is not particularly limited, and conventionally known dispersers such as a three-one motor, a homogenizer, a media type disperser, and a pressure disperser can be used.
• the fine particles in the slurry have an average particle size of less than 0.1 ⁇ m and a specific surface area of 50 m. 2 / G or more of fine particles (a) and fine particles (b) having an average particle diameter of 0.2 ⁇ m or more, and the weight ratio of fine particles (b) to fine particles (a) is 0.05 to 50
• the weight ratio of the fine particles to the water-soluble polymer is 1 to 100.
• As the medium water or an organic solvent such as ethanol or isopropanol, or a mixed solvent of water and an organic solvent such as ethanol is used.
• the water-soluble polymer, fine particles (a), and fine particles (b) contained in the slurry for A film formation are the same as those described in the above separator.
• the water-soluble polymer cellulose ether, polyvinyl alcohol and sodium alginate are preferable, and CMC is particularly preferable.
• fine particles (a) and fine particles (b) fine particles made of an inorganic material or an organic material can be used.
• an inorganic material is preferable, and alumina is particularly preferable.
• the materials of the fine particles (a) and the fine particles (b) may be the same as each other or different from each other.
• other fine particles other than the fine particles (a) and the fine particles (b) may be contained within a range not significantly impairing the object of the present invention.
• the ratio of the content of the other fine particles in the slurry is preferably 100% by weight or less (including 0% by weight), preferably 50% by weight or less, based on the total weight of the fine particles (a) and (b). More preferably (including 0% by weight).
• a surfactant, a pH adjuster, a dispersant, a plasticizer, and the like can be added to the slurry as long as the object of the present invention is not significantly impaired.
• a slurry containing a water-soluble polymer, fine particles, and a medium is coated on the polyolefin porous film in the conventional separator manufacturing process, the water-soluble polymer in the slurry and the medium are finely divided into the polyolefin porous film.
• the fine particles (a) contained in the slurry have a large specific surface area, the medium and the water-soluble polymer can be adsorbed and held on the surfaces of the fine particles (a). Due to the size of the fine particles (a) themselves, it is difficult to physically enter the pores of the B film. As a result, when the slurry contains fine particles (a), the fine particles (a) suppress excessive entry of the water-soluble polymer into the pores of the B film.
• the weight ratio of the fine particles (b) to the fine particles (a) is 0.05 to 50, preferably 0.1 to 15 and particularly preferably 0.2 to 10.
• the thickness of the A film can be kept moderate, the thermal shrinkage of the A film can be suppressed, and the A film has sufficient mechanical properties.
• the concentration of the water-soluble polymer in the sum of the water-soluble polymer and the medium in the slurry is 0.4% by weight or more and 1.3% by weight or less (based on the weight of the water-soluble polymer and the medium), preferably 0.4% by weight. % To 1.0% by weight. When the concentration of the water-soluble polymer is less than 0.4% by weight, the effect of adsorbing and holding the water-soluble polymer by the fine particles (a) is insufficient, and the adhesion of the coating film is poor.
• the molecular weight of the water-soluble polymer can be appropriately selected so as to obtain a slurry viscosity suitable for coating.
• the solid content concentration in the slurry (total concentration of fine particles (a) and fine particles (b) with respect to the slurry) is preferably 6 to 50% by weight, more preferably 9 to 25% by weight. If the solid content concentration is less than 6% by weight, it is difficult to remove the medium from the slurry, and if it exceeds 50% by weight, the slurry must be applied thinly on the B film, which is difficult to apply.
• the slurry In manufacturing the A film, when the A film forming slurry is applied on the B film, the slurry enters the pores (voids) of the B film, and the water-soluble polymer in the slurry is precipitated. The A film and the B film are bonded by the “anchor effect”. At this time, if the slurry enters excessively into the pores of the B membrane, the water-soluble polymer penetrates deeper into the pores of the B membrane and then precipitates, thereby inhibiting smooth melting of the B membrane at the time of shutdown. There is a problem. This problem can be avoided by suppressing the slurry containing the water-soluble polymer from excessively entering the pores (voids) of the B film.
• the S value represented by the following formula is 200 m. 2 / G or more, more preferably 300 m 2 / G or more.
• the upper limit value of the fine particles (b) is not limited as long as the shape of the A film can be maintained, but is usually 20 ⁇ m or less, preferably 5 ⁇ m or less, more preferably 1 ⁇ m or less, and even more preferably 0.00. 8 ⁇ m or less.
• the method of applying the slurry to the B film to obtain the coated film is not particularly limited as long as it is a method that enables uniform wet coating, and a conventionally known method can be adopted.
• a capillary coating method, a spin coating method, a slit coating method, a spray coating method, a dip coating method, a roll coating method, a screen printing method, a flexographic printing method, a bar coater method, a gravure coater method, a die coater method, etc. are adopted. be able to.
• the thickness of the A film can be controlled by adjusting the thickness of the coating film, the concentration of the water-soluble polymer in the slurry, and the ratio of the fine particles to the water-soluble polymer.
• a resin film, a metal belt, a drum, or the like can be used as a support for supporting the B film.
• the removal of the medium from the coating film is generally performed by drying.
• a solvent that can dissolve in the medium but does not dissolve the water-soluble polymer is prepared, and the coating film is immersed in the solvent to replace the medium with the solvent.
• the method of depositing a property polymer, removing a medium, and removing a solvent by drying is mentioned.
• the drying temperature of the medium or the solvent is preferably a temperature that does not decrease the air permeability of the B film.
• nonaqueous electrolyte secondary battery an example of a lithium ion secondary battery is demonstrated as a nonaqueous electrolyte secondary battery. Although components other than a separator are demonstrated especially, it is not limited to these.
• a nonaqueous electrolytic solution for example, a nonaqueous electrolytic solution in which a lithium salt is dissolved in an organic solvent can be used.
• lithium salt LiClO 4 , LiPF 6 , LiAsF 6 , LiSbF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , Li 2 B 10 Cl 10 , Lower aliphatic carboxylic acid lithium salt, LiAlCl 4 Among them, one kind or a mixture of two or more kinds may be mentioned.
• the non-aqueous electrolyte include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, 1,2-di (methoxycarbonyloxy) Carbonates such as ethane; ethers such as 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran Esters such as methyl formate, methyl
• cyclic carbonates and acyclic carbonates are preferred, and cyclic carbonates and acyclic carbonates, or mixtures of cyclic carbonates and ethers are more preferred.
• ethylene carbonate and dimethyl have a wide operating temperature range and are hardly decomposable even when a graphite material such as natural graphite or artificial graphite is used as the negative electrode active material.
• a mixture comprising carbonate and ethyl methyl carbonate is preferred.
• the positive electrode sheet a sheet in which a positive electrode mixture containing a positive electrode active material, a conductive material and a binder is supported on a positive electrode current collector is usually used.
• a method of supporting the positive electrode mixture on the positive electrode current collector As a method of supporting the positive electrode mixture on the positive electrode current collector, a method of pressure molding; a positive electrode mixture paste is obtained by further using an organic solvent, the paste is applied to the positive electrode current collector, and dried. And a method of pressing the obtained sheet and fixing the positive electrode mixture to the positive electrode current collector.
• the positive electrode active material a material containing a material that can be doped / undoped with lithium ions, a carbonaceous material as a conductive material, and a thermoplastic resin as a binder can be used.
• a conductor such as Al, Ni, and stainless steel can be used, but Al is preferable in that it is easily processed into a thin film and is inexpensive.
• Examples of the material that can be doped / undoped with lithium ions include lithium composite oxides containing at least one transition metal such as V, Mn, Fe, Co, and Ni. Among these, ⁇ -NaFeO such as lithium nickelate and lithium cobaltate is preferable in that the average discharge potential is high. 2 And lithium composite oxides having a spinel structure such as lithium composite oxide having a lithium structure and lithium manganese spinel.
• the lithium composite oxide may contain various metal elements, particularly at least selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Cu, Ag, Mg, Al, Ga, In, and Sn.
• the metal element is included so that the at least one metal element is 0.1 to 20 mol% with respect to the sum of the number of moles of one metal element and the number of moles of Ni in lithium nickelate. It is preferable to use composite lithium nickelate because the cycle performance in use at a high capacity is improved.
• binder polyvinylidene fluoride, vinylidene fluoride copolymer, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer
• examples include ethylene-tetrafluoroethylene copolymers, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymers, thermoplastic resins such as thermoplastic polyimide, polyethylene, and polypropylene.
• the conductive agent include carbonaceous materials such as natural graphite, artificial graphite, cokes, and carbon black.
• each may be used alone, for example, artificial graphite and carbon black may be mixed and used.
• the negative electrode sheet for example, a material capable of doping and dedoping lithium ions, lithium metal, or a lithium alloy can be used.
• Materials that can be doped / undoped with lithium ions include carbonaceous materials such as natural graphite, artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers, and fired organic polymer compounds, and lower potential than the positive electrode.
• chalcogen compounds such as oxides and sulfides for doping and dedoping lithium ions.
• a carbonaceous material a carbonaceous material mainly composed of graphite materials such as natural graphite and artificial graphite, because it has a high potential flatness and a low average discharge potential, so that a large energy density can be obtained when combined with a positive electrode.
• the negative electrode current collector Cu, Ni, stainless steel, or the like can be used.
• Cu is preferable because it is difficult to form an alloy with lithium and it can be easily processed into a thin film.
• a pressure molding method As a method of supporting the negative electrode mixture containing the negative electrode active material on the negative electrode current collector, a pressure molding method; a negative electrode mixture paste is obtained by further using a solvent or the like, and the paste is applied to the negative electrode current collector. Examples thereof include a method of pressing and drying the obtained sheet and fixing the negative electrode mixture to the negative electrode current collector.
• the shape of the battery is not particularly limited, and may be any of a paper type, a coin type, a cylindrical type, a rectangular shape, and the like.
• the separator When producing a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte secondary battery separator of the present invention, the separator has a high load characteristic, and even when abnormal heat generation occurs, the separator exhibits a shutdown function, and further A non-aqueous electrolyte secondary battery that can suppress heat generation and can avoid contact between the positive electrode and the negative electrode due to shrinkage of the separator even when the temperature is further increased can be obtained.
• the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
• the basis weight of the A membrane was calculated by subtracting the basis weight of the polyolefin porous membrane (B membrane) as the base material from the basis weight of the laminated porous film (separator).
• Porosity (unit: volume%) The film was cut into a 10 cm long square, and weight: W (g) and thickness: D (cm) were measured. The weight of the material in the sample was divided by calculation, the weight of each material: Wi (g) was divided by the true specific gravity, the volume of each material was calculated, and the porosity (volume%) was obtained from the following formula. .
• Porosity (volume%) 100-[ ⁇ (W1 / true specific gravity 1) + (W2 / true specific gravity 2) + ..
• Air permeability (unit: sec / 100cc) The air permeability of the separator was measured with a digital timer type Gurley type densometer manufactured by Toyo Seiki Seisakusho Co., Ltd. based on JIS P8117. (5) Shutdown ultimate resistance measurement The shutdown temperature was measured with a cell for shutdown measurement (hereinafter referred to as “cell”). A 2 ⁇ 3 cm square rectangular membrane was impregnated with an electrolytic solution, and then sandwiched between two SUS electrodes and fixed with clips to prepare a cell.
• the electrolytic solution a solution obtained by dissolving 1 mol / L LiBF 4 in a mixed solvent of ethylene carbonate 50 vol%: diethyl carbonate 50 vol% was used.
• the terminals of the impedance analyzer were connected to both poles of the assembled cell.
• the resistance value at 1 kHz was measured. Resistance was measured while increasing the temperature at a rate of 15 ° C./min in an oven. The maximum resistance value was defined as the ultimate resistance value.
• the shutdown property was evaluated according to the following criteria. Evaluation of shutdown performance: A: Ultimate resistance value is 500 ⁇ or more.
• A: Ultimate resistance value is 200 ⁇ or more and less than 500 ⁇ .
• X Ultimate resistance value is less than 200 ⁇ .
• the water-soluble polymer, fine particles (a) and fine particles (b), and B film used for forming the A film are as follows. ⁇ A film> "Water-soluble polymer”: Carboxymethylcellulose (CMC): Serogen 4H manufactured by Daiichi Kogyo Seiyaku Co., Ltd. “Fine particles (a)”: Fine particles (a1): AKP-G008 manufactured by Sumitomo Chemical Co., Ltd.
• Example 1 Average particle size: 0.54 ⁇ m Specific surface area: 4.3 m 2 / g Particle shape: Vertical type ⁇ B film> Polyethylene porous membrane “B1”: Film thickness: 15 ⁇ m Weight per unit: 7 g / m 2 Air permeability: 105 seconds / 100cc “B2”: Film thickness: 13 ⁇ m Fabric weight: 6.5 g / m 2 Air permeability: 120 seconds / 100cc
• Example 1 (1) Production of slurry The slurry of Example 1 was produced by the following procedure.
• 1000 parts by weight of fine particles (a1) and 3000 parts by weight of fine particles (b1) are added to the CMC solution (100 parts by weight of CMC), mixed, and mixed under high pressure dispersion conditions (60 MPa) using a gorin homogenizer.
• the slurry of Example 1 was produced by performing the process once. Table 1 shows the composition of the slurry of Example 1.
• the ratio of the total specific surface area (m 2 / g) and the CMC weight (g) of the fine particles (a1) calculated from the charged amounts of the fine particles (a1) and CMC was 700.
• (2) Manufacture and evaluation of separator B1 was used as a B film.
• the B film (MD direction 100 cm, TD direction 30 cm) was fixed to the drum, and a weight of 0.6 kg was suspended on the other side so that the B film was evenly loaded.
• a stainless steel coating bar having a diameter of 20 mm was arranged in parallel at the top of the drum so that the clearance from the drum was 40 ⁇ m. The drum was rotated and stopped so that the end of the side fixed with the B film tape was between the drum and the coating bar.
• Example 1 While supplying the slurry prepared above onto the B film before the coating bar, the drum was rotated at 0.5 rpm to apply the slurry to one surface of the B film. After coating, rotation of the drum was stopped, and it was left in an atmosphere of 70 ° C. for 30 minutes to be sufficiently dried, thereby obtaining the separator of Example 1 in which the A film was laminated on one surface of the B film. In the obtained separator, the A film was in close contact with the B film, and peeling was not confirmed.
• Table 2 shows the solid content weight ratio and physical properties of the separator obtained by the above evaluation method.
• Examples 2-8 (1) Production of Slurry Example 2 to 8 were carried out in the same manner as the slurry production method of Example 1 except that the fine particles (a) and fine particles (b) shown in Table 1 were used in the proportions shown in Table 1, respectively. A slurry was obtained. Table 1 shows the concentration of each component in the slurries of Examples 2 to 8. (2) Production and Evaluation of Separator The same operations as in Example 1 were performed except that the slurries of Examples 2 to 8 were used, and separators of Examples 2 to 8 were produced. The B film used is shown in Table 2. Table 2 shows the solid weight ratio and physical properties of the separator obtained. In the separators of Examples 2 to 8, the A film adhered to the B film, and no peeling was confirmed.
• Example 9 (1) Manufacture of slurry A slurry of Example 9 was obtained in the same manner as the slurry preparation method of Example 1 except that the proportions of the fine particles (a1) and fine particles (b1) were changed as shown in Table 1. Table 1 shows the concentration of each component in the slurry of Example 9. (2) Manufacture and Evaluation of Separator An A film was laminated on one surface of the B film by performing the same operation as in Example 1 except that the slurry of Example 9 was used. The B film used is shown in Table 2. Next, the separator of Example 9 was obtained by laminating the A film on the other surface of the B film in the same manner, thereby laminating the A film on both surfaces of the B film.
• Example 10-12 Production of slurry The slurries of Examples 10 to 12 were prepared in the same manner as the slurry production method of Example 1 except that the fine particles (a) and fine particles (b) shown in Table 1 were used in the proportions shown in Table 1. Obtained. Table 1 shows the concentration of each component in the slurries of Examples 10-12.
• Example 9 Production and Evaluation of Separator
• the same operations as in Example 9 were performed except that the slurries of Examples 10 to 12 were used to obtain separators of Examples 10 to 12 in which the A film was laminated on both sides of the B film. .
• the B film used is shown in Table 2.
• Table 2 shows the solid weight ratio and physical properties of the separator obtained.
• membrane is the total thickness of A film
• Comparative Example 1 (1) Manufacture of slurry The slurry of Comparative Example 1 was prepared in the same manner as the slurry preparation method of Example 1 except that only the fine particles (b1) were used as the fine particles and the other components were in the proportions shown in Table 1. Obtained. Table 1 shows the concentration of each component in the slurry of Comparative Example 1. (2) Manufacture and Evaluation of Separator A separator of Comparative Example 1 was produced by performing the same operation as in Example 1 except that the slurry of Comparative Example 1 was used. The B film used is shown in Table 2. Table 2 shows the solid weight ratio and physical properties of the separator obtained. In the separator of Comparative Example 1, the A film adhered onto the B film, and no peeling was confirmed.
• Comparative Example 2 (1) Production of slurry The slurry of Comparative Example 1 was prepared in the same manner as the slurry production method of Example 1 except that only the fine particles (a1) were used as the fine particles and the other components were in the proportions shown in Table 1. Obtained. Table 1 shows the concentration of each component in the slurry of Comparative Example 1. (2) Manufacture and Evaluation of Separator A separator of Comparative Example 2 was produced by performing the same operation as in Example 1 except that the slurry of Comparative Example 2 was used. The B film used is shown in Table 2. Table 2 shows the solid weight ratio and physical properties of the separator obtained. In the separator of Comparative Example 2, the A film adhered to the B film, and peeling was not confirmed.
• Comparative Example 3 (1) Production of slurry The same procedure as in the slurry production method of Example 1, except that the fine particles (a) and fine particles (b) shown in Table 1 were used, and the ratios of the other components were as shown in Table 1. A slurry of Comparative Example 3 was obtained. Table 1 shows the concentration of each component in the slurry of Comparative Example 1. (2) Manufacture and Evaluation of Separator A separator of Comparative Example 3 was produced by performing the same operation as in Example 1 except that the slurry of Comparative Example 3 was used. The B film used is shown in Table 2. Table 2 shows the solid weight ratio and physical properties of the separator obtained. In the separator of Comparative Example 3, peeling of the A film was remarkable, and a continuous film could not be formed on the B film.
• Comparative Example 4 (1) Manufacture of slurry The slurry of Comparative Example 4 was prepared in the same manner as the slurry preparation method of Example 1, except that only the fine particles (b2) were used as the fine particles and the other components were in the proportions shown in Table 1. Obtained. Table 1 shows the concentration of each component in the slurry of Comparative Example 1. (2) Manufacture and Evaluation of Separator The same operation as in Example 9 was performed except that the slurry of Comparative Example 4 was used to obtain the separator of Comparative Example 4 in which the A film was laminated on both surfaces of the B film. The B film used is shown in Table 2. Table 2 shows the solid weight ratio and physical properties of the separator obtained.
• membrane is the total thickness of A film
• the separator of Comparative Example 4 the A film adhered to the B film, and peeling was not confirmed.
• the dimension maintenance rate (heating shape maintenance rate) and the SD characteristics were evaluated. The results are shown in Table 3.
• a separator for a non-aqueous electrolyte secondary battery that is excellent in shutdown performance and air permeability in addition to shape stability at high temperatures.
• the separator prevents the positive electrode and the negative electrode from coming into direct contact, and the polyolefin porous film is made nonporous so that the insulating property is improved.
• a non-aqueous electrolyte secondary battery that can be maintained is obtained.
• the separator can be produced with good reproducibility.

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