WO2012005152A1 - Separator for non-aqueous battery, and non-aqueous battery - Google Patents

Separator for non-aqueous battery, and non-aqueous battery Download PDF

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Publication number
WO2012005152A1
WO2012005152A1 PCT/JP2011/064925 JP2011064925W WO2012005152A1 WO 2012005152 A1 WO2012005152 A1 WO 2012005152A1 JP 2011064925 W JP2011064925 W JP 2011064925W WO 2012005152 A1 WO2012005152 A1 WO 2012005152A1
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Prior art keywords
heat
fine particles
resistant porous
separator
porous membrane
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PCT/JP2011/064925
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French (fr)
Japanese (ja)
Inventor
片山秀昭
松本修明
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日立マクセル株式会社
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Priority to JP2012502371A priority Critical patent/JPWO2012005152A1/en
Publication of WO2012005152A1 publication Critical patent/WO2012005152A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • 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 heat-resistant porous membrane suitable for application to a separator separating a positive electrode and a negative electrode in a non-aqueous battery, a separator for a non-aqueous battery using the heat-resistant porous membrane, and the heat-resistant porous membrane.
  • the present invention relates to a nonaqueous battery having a membrane or the separator for a nonaqueous battery and having excellent output characteristics and safety.
  • a lithium secondary battery which is a type of non-aqueous battery, is widely used as a power source for portable devices such as mobile phones and notebook personal computers because of its high energy density.
  • portable devices such as mobile phones and notebook personal computers
  • an in-vehicle power source such as an electric assist bicycle, an electric motorcycle, an electric vehicle, and a hybrid vehicle
  • Since such a power source for in-vehicle use has a larger capacity than a power source for portable devices, it is important to ensure further safety.
  • the required output is larger than the power supply of the portable device, a safety technology that does not deteriorate the output characteristics is required.
  • a polyolefin microporous film having a thickness of about 20 to 30 ⁇ m is used as a separator interposed between a positive electrode and a negative electrode.
  • separator material the constituent resin of the separator is melted below the abnormal heat generation temperature of the battery to close the pores, thereby increasing the internal resistance of the battery and improving the safety of the battery in the event of a short circuit.
  • a material having a low melting point may be used among polyolefins such as polyethylene.
  • a separator for example, a uniaxially stretched film or a biaxially stretched film is used for increasing the porosity and improving the strength. Since such a separator is supplied as a single film, a certain strength is required in terms of workability and the like, and this is secured by the stretching. However, such a stretched film has increased crystallinity, and the shutdown temperature has increased to a temperature close to the abnormal heat generation temperature of the battery, so that the margin for ensuring the safety of the battery is not sufficient. hard.
  • the film is distorted by the stretching, and when it is exposed to high temperature, there is a problem that shrinkage occurs due to residual stress.
  • the shrinkage temperature is very close to the melting point, ie the shutdown temperature.
  • the current must be immediately reduced to prevent the battery temperature from rising. This is because if the pores are not sufficiently closed and the current cannot be reduced immediately, the battery temperature easily rises to the shrinkage temperature of the separator, and there is a risk of abnormal heat generation due to an internal short circuit.
  • Patent Documents 1 to 3 As a technique for preventing such a short circuit due to thermal contraction of the separator and improving the reliability of the battery, for example, a porous base material having good heat resistance, filler particles, and a resin component for ensuring a shutdown function It has been proposed to form an electrochemical element with a separator having the above (Patent Documents 1 to 3).
  • Patent Documents 4 to 6 it has been proposed to increase heat resistance by forming a heat-resistant layer mainly composed of heat-resistant resin or inorganic fine particles on a polyolefin porous film.
  • Patent Documents 1 to 6 it is possible to provide a battery with excellent safety that is unlikely to generate abnormal heat even when the battery is abnormal.
  • the present invention has been made in view of the above circumstances, and can be used as a nonaqueous battery having high safety and high output characteristics, a separator between a positive electrode and a negative electrode, and heat resistance capable of constituting the nonaqueous battery.
  • a porous membrane and a separator capable of constituting the nonaqueous battery are provided.
  • the separator for a non-aqueous battery according to the present invention is a separator for a non-aqueous battery in which a porous substrate and a heat-resistant porous membrane are integrated, and the heat-resistant porous membrane has a heat-resistant temperature of 150 ° C.
  • the fine particles Including the fine particles and an organic binder, the fine particles have an average particle diameter of 0.01 to 10 ⁇ m, and the proportion of the organic binder in the total solid content of the heat-resistant porous film is 7% by volume. It is characterized by the following.
  • the first nonaqueous battery of the present invention is a nonaqueous battery including a positive electrode, a negative electrode, a heat resistant porous membrane and a nonaqueous electrolyte, and is selected from the heat resistant porous membrane, the positive electrode and the negative electrode.
  • the heat-resistant porous membrane contains fine particles having a heat-resistant temperature of 150 ° C. or higher and an organic binder, and the average particle diameter of the fine particles is 0.01 to 10 ⁇ m.
  • the ratio of the organic binder in the total solid content of the heat-resistant porous membrane is 7% by volume or less.
  • the second non-aqueous battery of the present invention is a non-aqueous battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the separator is formed by integrating a porous substrate and a heat-resistant porous film.
  • the heat-resistant porous film includes fine particles having a heat-resistant temperature of 150 ° C. or more and an organic binder, and the fine particles have an average particle diameter of 0.01 to 10 ⁇ m, and the heat-resistant porous film
  • the ratio of the organic binder in the total solid content of is 7% by volume or less.
  • a non-aqueous battery having high safety and high output characteristics a heat-resistant porous membrane capable of functioning as a separator between a positive electrode and a negative electrode and constituting the non-aqueous battery, and the non-aqueous battery Can be provided.
  • FIG. 1 is a cross-sectional view showing an example of the lithium secondary battery of the present invention.
  • the heat-resistant porous membrane of the present invention contains at least a fine particle having a heat-resistant temperature of 150 ° C. or higher and an organic binder, and is suitable as a separator for partitioning the positive electrode and the negative electrode in a non-aqueous battery. .
  • the heat-resistant porous membrane of the present invention acts as a separator that separates the positive electrode and the negative electrode in the non-aqueous battery, for example, by being integrated with at least one of the positive electrode and the negative electrode of the non-aqueous battery.
  • a non-aqueous battery separator as an independent film by being integrated with a porous substrate.
  • the total volume of all solids (total volume of components of the heat resistant porous membrane excluding the voids. The same applies to the “total volume of the minute.”)
  • the ratio of the volume of the organic binder in the volume is 7% by volume or less.
  • the proportion of the organic binder in the total solid content of the heat-resistant porous membrane is preferably 5% by volume or less, more preferably 3% by volume or less. More preferably, it is 1 volume% or less.
  • an organic binder having an amide group in the molecule, which will be described later, especially a homopolymer or copolymer of N-vinylacetamide a porous film is formed when the proportion of the fine particles is large. Therefore, it is desirable to reduce the proportion of the organic binder as much as possible from the viewpoint of imparting flexibility to the heat-resistant porous film.
  • the proportion of the organic binder in the heat-resistant porous film is too small, for example, the force for binding fine particles having a heat-resistant temperature of 150 ° C. or higher becomes weak, and the fine particles are likely to fall off from the heat-resistant porous film.
  • the heat-resistant porous film may be easily peeled off from the electrode and the porous substrate. Therefore, the proportion of the organic binder in the total solid content of the heat resistant porous membrane is preferably 0.5% by volume or more.
  • the components in the heat-resistant porous film, the heat-resistant porous film and the porous substrate or electrode can be satisfactorily bonded, and are electrochemically stable and non-aqueous
  • electrolyte non-aqueous electrolyte
  • tensile strength and tensile modulus it has good adhesion to fine particles with a heat resistant temperature of 150 ° C or higher. Therefore, those having an amide group (amide bond) in the molecule are preferred, and those containing a structural unit derived from a monomer represented by the following general formula (1) are more preferred.
  • the organic binder containing a structural unit derived from a monomer represented by the following general formula (1) has a side chain containing a moiety [—NR 3 — (C ⁇ O) —R 2 ] containing an amide group. Become.
  • R 1 is hydrogen or a methyl group
  • R 2 and R 3 are R 2 is hydrogen or an alkyl group having 1 to 6 carbon atoms
  • R 3 is hydrogen or an alkyl group having 1 to 4 carbon atoms.
  • R 2 and R 3 are bonded to each other to form a ring, and the total number of carbon atoms in R 2 and R 3 of the ring is 2 to 10.
  • the alkyl group having 1 to 6 carbon atoms in R 2 includes all alkyl groups having 1 to 6 carbon atoms such as a linear alkyl group, a branched alkyl group, and a cyclic alkyl group.
  • the alkyl group having 1 to 4 carbon atoms in R 3 includes all alkyl groups having 1 to 4 carbon atoms such as a linear alkyl group, a branched alkyl group, and a cyclic alkyl group.
  • Examples of the organic binder containing a structural unit derived from the monomer represented by the general formula (1) include a homopolymer and a copolymer of the monomer represented by the general formula (1).
  • Examples of the monomer represented by the general formula (1) include N-vinylacetamide, N-vinylformamide, N-methyl, N-vinylformamide, N-vinylpyrrolidone, N-vinyl-2-caprolactam and the like. It is done.
  • poly N-vinylacetamide for example, poly N-vinylformamide, poly N-methyl, N-vinylformamide, poly N-vinylpyrrolidone, Examples thereof include poly N-vinyl-2-caprolactam.
  • Examples of the copolymer of the monomer represented by the general formula (1) include a copolymer of N-vinylacetamide and an ethylenically unsaturated monomer other than N-vinylacetamide; N-vinylformamide, N -Copolymer of ethylenically unsaturated monomers other than vinylformamide; Copolymer of N-methyl, N-vinylformamide and ethylenically unsaturated monomers other than N-methyl, N-vinylformamide; N-vinyl And a copolymer of pyrrolidone and an ethylenically unsaturated monomer other than N-vinylpyrrolidone.
  • the copolymer using the monomer represented by the said General formula (1) is also contained in the copolymer of the monomer represented by the said General formula (1).
  • Examples of the ethylenically unsaturated monomer [ethylenically unsaturated monomer other than the monomer represented by the general formula (1)] that can be used for forming the copolymer include acrylic acid, methacrylic acid, methyl acrylate, and ethyl.
  • the copolymerization ratio (mass ratio) in the copolymer of the monomer represented by the general formula (1) and the ethylenically unsaturated monomer other than the monomer represented by the general formula (1) is the latter ethylenic property.
  • the unsaturated monomer is preferably 2 to 50% by mass.
  • the molecular weight of an organic binder having an amide group in the molecule is a number average measured using gel permeation chromatography.
  • the molecular weight (in terms of polystyrene) is preferably 1000 or more, more preferably 4000 or more, and preferably 1000000 or less, more preferably 700000 or less, and 500000 or less. Further preferred.
  • heat-resistant porous membranes include ethylene-vinyl acetate copolymer (EVA, having a structural unit derived from vinyl acetate of 20 to 35 mol%), (meth) acrylate polymer [What is “(meth) acrylate”? , And acrylate and methacrylate. same as below. ], Fluorine type rubber, styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), one or more types of resins such as polyurethane may be used as the organic binder.
  • SBR styrene butadiene rubber
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • resins such as polyurethane
  • the fine particles having a heat resistant temperature of 150 ° C. or more related to the heat resistant porous film are used as a main component of the heat resistant porous film or fill a void formed between fibrous materials to be described later. It has the effect of suppressing the occurrence of the short circuit.
  • the term “heat-resistant temperature is 150 ° C. or higher” in fine particles having a heat-resistant temperature of 150 ° C. or higher and fibrous materials having a heat-resistant temperature of 150 ° C. or higher (described later) refers to deformation at least at 150 ° C. This means that no shape change is visually confirmed.
  • the fine particles having a heat-resistant temperature of 150 ° C. or higher have electrical insulation properties, are electrochemically stable, and further have a non-aqueous electrolyte (non-aqueous electrolyte solution) or a composition for forming a heat-resistant porous film. If it is stable with respect to the solvent used for a thing (composition containing a solvent), there will be no restriction
  • “stable with respect to the non-aqueous electrolyte” means that no deformation or chemical composition change occurs in the non-aqueous electrolyte of the non-aqueous battery.
  • electrochemically stable as used in the present specification means that no chemical change occurs during charging / discharging of the battery.
  • Such fine particles having a heat-resistant temperature of 150 ° C. or more include, for example, oxide fine particles such as iron oxide, SiO 2 , Al 2 O 3 , TiO 2 , BaTiO 3 , ZrO 2 ; aluminum nitride, silicon nitride, etc.
  • Nitride fine particles Calcium fluoride, barium fluoride, barium sulfate and other poorly soluble ionic crystal fine particles; silicon, diamond and other covalently bonded crystal fine particles; talc, montmorillonite and other clay fine particles; boehmite, zeolite, apatite, kaolin Inorganic fine particles such as mullite, spinel, olivine, sericite, bentonite, hydrotalcite, and other mineral resource-derived substances or artificial products thereof.
  • the surface of conductive fine particles such as metal fine particles; oxide fine particles such as SnO 2 and tin-indium oxide (ITO); carbonaceous fine particles such as carbon black and graphite; It may be fine particles that have been made electrically insulating by surface treatment with the above-mentioned materials constituting the electrically insulating fine particles.
  • organic fine particles can be used for the fine particles having a heat resistant temperature of 150 ° C. or higher.
  • organic fine particles include polyimide, melamine resin, phenol resin, crosslinked polymethylmethacrylate (crosslinked PMMA), crosslinked polystyrene (crosslinked PS), polydivinylbenzene (PDVB), benzoguanamine-formaldehyde condensate, etc.
  • Molecular fine particles; heat-resistant polymer fine particles such as thermoplastic polyimide;
  • the organic resin (polymer) constituting these organic fine particles is a mixture, modified body, derivative, copolymer (random copolymer, alternating copolymer, block copolymer, graft copolymer) of the materials exemplified above. ) Or a crosslinked product (in the case of the heat-resistant polymer).
  • the various fine particles exemplified above may be used alone or in combination of two or more.
  • the fine particles having a heat resistant temperature of 150 ° C. or higher may be particles containing two or more kinds of materials constituting the various fine particles exemplified above.
  • inorganic oxide fine particles are preferable, and alumina, silica, and boehmite are more preferable because, for example, the oxidation resistance of the heat-resistant porous film can be further improved.
  • the form of the fine particles having a heat resistant temperature of 150 ° C. or higher may be any form such as a spherical shape, a particle shape, or a plate shape, but a plate shape is preferable.
  • the plate-like particles include various commercially available products. For example, “Sun Green” (SiO 2 ) manufactured by Asahi Glass Stech Co., Ltd., “NST-B1” pulverized product (TiO 2 ) manufactured by Ishihara Sangyo Co., Ltd., Sakai Chemical Industry Co., Ltd.
  • the fine particles having a heat-resistant temperature of 150 ° C. or higher are plate-like, the fine particles are oriented in the heat-resistant porous film so that the flat plate surface is substantially parallel to the surface of the heat-resistant porous film.
  • the use of such a heat-resistant porous membrane can better suppress the occurrence of short circuits in the battery. This is because the fine particles having a heat-resistant temperature of 150 ° C. or more are oriented as described above, and the fine particles are arranged so as to overlap each other on a part of the flat plate surface, so that the heat-resistant porous film is directed from one side to the other side.
  • the aspect ratio (maximum length in the plate-like particles / thickness of the plate-like particles) is preferably 5 or more as the form when the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like particles. 10 or more is more preferable, 100 or less is preferable, and 50 or less is more preferable.
  • the average value of the ratio of the length in the major axis direction to the length in the minor axis direction (length in the minor axis direction / length in the major axis direction) of the tabular surface of the grain is preferably 0.3 or more, 0.5 It is more preferable that the number is 1 (that is, the length in the major axis direction and the length in the minor axis direction may be the same).
  • the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like particles having the aspect ratio and the average value of the ratio of the long axis direction length to the short axis direction of the flat plate surface, the above-mentioned short circuit prevention The effect is exhibited more effectively.
  • the average value of the ratio of the length in the major axis direction to the length in the minor axis direction of the flat plate surface when the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like for example, an image taken with a scanning electron microscope (SEM) Can be obtained by image analysis. Further, the aspect ratio in the case where the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like can also be obtained by image analysis of an image taken by SEM.
  • the average particle size of the fine particles having a heat resistant temperature of 150 ° C. or higher is too small, the amount of the organic binder may not be sufficient to bind the fine particles. It is preferably 1 ⁇ m or more. However, if the average particle size of the fine particles having a heat resistant temperature of 150 ° C. or higher is too large, the heat resistant porous membrane becomes too thick, and there is a risk that the energy density of a battery using this will decrease. Therefore, the average particle diameter of the fine particles having a heat resistant temperature of 150 ° C. or higher is 10 ⁇ m or less, and preferably 5 ⁇ m or less. As used herein, the average particle size of the fine particles having a heat resistance temperature of 150 ° C.
  • a laser scattering particle size distribution meter for example, “LA-920” manufactured by HORIBA
  • LA-920 manufactured by HORIBA
  • It can be defined as a number average particle diameter measured by dispersing fine particles having a heat resistant temperature of 150 ° C. or higher in a medium in which the fine particles are not dissolved or fine particles having a heat resistant temperature of 150 ° C. or higher are not swollen.
  • the specific surface area of the fine particles having a heat resistant temperature of 150 ° C. or higher is preferably 100 m 2 / g or less, more preferably 50 m 2 / g or less, and further preferably 30 m 2 / g or less.
  • the specific surface area of the fine particles having a heat-resistant temperature of 150 ° C. or higher is increased, generally, the amount of the organic binder required to bind the fine particles to each other well, and the fine particles to the base material and the electrode tends to increase. There is a possibility that it is difficult to adjust the ratio of the organic binder in the heat-resistant porous film to the above value.
  • the specific surface area of the fine particles having a heat resistant temperature of 150 ° C. or higher is preferably 1 m 2 / g or higher.
  • the specific surface area of fine particles having a heat resistant temperature of 150 ° C. or higher is a value measured by a BET method using nitrogen gas.
  • the heat-resistant porous film of the present invention uses fine particles having high heat resistance such as a heat-resistant temperature of 150 ° C. or higher, the action prevents thermal shrinkage at high temperatures and has high dimensional stability. is doing. Furthermore, when such a heat-resistant porous film having high heat resistance is integrated with the electrode (positive electrode and / or negative electrode), the overall dimensional stability of the heat-resistant porous film at high temperatures is further improved.
  • the separator for a non-aqueous battery of the present invention in which the porous substrate and the heat-resistant porous membrane of the present invention are integrated is a porous substrate whose temperature is high, such as a polyolefin microporous membrane.
  • the non-aqueous battery having the heat-resistant porous membrane of the present invention integrated with the electrode and the non-aqueous battery having the non-aqueous battery separator of the present invention are composed of, for example, only a conventional polyethylene microporous membrane. Since the occurrence of a short circuit due to the thermal contraction of the separator that has occurred in the battery using the separator can be prevented, the reliability and safety when the inside of the battery is abnormally overheated can be further increased.
  • nonaqueous battery having the heat resistant porous membrane of the present invention prevention of a short circuit due to the thermal contraction of the separator at a high temperature is achieved with a configuration other than increasing the thickness of the separator, for example. Therefore, it is possible to make the thickness of the separator (the heat-resistant porous membrane of the present invention or the separator for a non-aqueous battery of the present invention) that separates the positive electrode and the negative electrode relatively thin, thereby reducing the energy density. Can be suppressed as much as possible.
  • the amount of fine particles having a heat resistant temperature of 150 ° C. or higher in the heat resistant porous membrane is from the viewpoint of more effectively exerting the effect of using the fine particles, in the total volume of the total solid content of the heat resistant porous membrane, It is preferably 10% by volume or more, more preferably 30% by volume or more, and still more preferably 40% by volume or more.
  • the heat-resistant porous film does not contain a fibrous material, which will be described later, and contains a heat-meltable fine particle or a swellable fine particle, which will be described later, and has a shutdown function
  • the heat resistance of the fine particles having a heat-resistant temperature of 150 ° C. or higher is preferably 80% by volume or less in the total volume of the total solid content of the heat resistant porous membrane, for example.
  • the heat-resistant porous film does not contain a fibrous material described later and does not have a shutdown function
  • the amount of fine particles having a heat-resistant temperature of 150 ° C. or higher in the heat-resistant porous film is much larger. Specifically, there is no problem if it is 99.5% by volume or less in the total volume of the total solid content of the heat-resistant porous membrane.
  • fine particles having a heat-resistant temperature of 150 ° C. or higher The amount in the heat resistant porous membrane is preferably 70% by volume or less in the total volume of the total solid content of the heat resistant porous membrane, for example.
  • the amount of fine particles having a heat-resistant temperature of 150 ° C. or higher in the heat-resistant porous film may be larger. Specifically, there is no problem as long as it is 80% by volume or less in the total volume of the total solid content of the heat-resistant porous membrane.
  • the heat resistant porous membrane may contain a fibrous material.
  • a fibrous material By containing a fibrous material, the strength of the heat-resistant porous film can be increased.
  • the “fibrous material” in the present specification means that having an aspect ratio [length in the longitudinal direction / width (diameter) in a direction perpendicular to the longitudinal direction] of 4 or more.
  • the aspect ratio of the fibrous material is preferably 10 or more.
  • the fibrous material preferably has a heat resistant temperature of 150 ° C. or higher.
  • a material that can be melted at a temperature of 140 ° C. or less to block the pores of the heat-resistant porous film and provide a function of blocking the movement of ions in the heat-resistant porous film (so-called shutdown function)
  • shutdown function a function of blocking the movement of ions in the heat-resistant porous film
  • a fibrous material having a heat-resistant temperature of 150 ° C. or higher is also contained in the porous membrane, so that a shutdown occurs due to heat generation in the battery, and then 10 Even if the temperature of the separator rises by more than 0 ° C., the shape can be kept more stable.
  • the deformation can be substantially eliminated.
  • the fibrous material preferably has a heat-resistant temperature of 150 ° C. or higher, and has an electrical insulating property, is electrochemically stable, and further has a non-aqueous electrolyte (non-aqueous electrolyte) included in a non-aqueous battery, It is more preferable if the solvent used in the heat-resistant porous film-forming composition is stable.
  • constituent materials of the fibrous material include, for example, cellulose, modified cellulose (such as carboxymethyl cellulose), polypropylene (PP), polyester [polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT). And the like], resins such as polyacrylonitrile (PAN), aramid, polyamideimide, and polyimide; inorganic materials (inorganic oxides) such as glass, alumina, and silica; and the like.
  • the fibrous material may contain one kind of these constituent materials, or may contain two or more kinds.
  • the fibrous material may contain various known additives (for example, an antioxidant in the case of a resin) as necessary. Absent.
  • the fibrous material may be subjected to a surface treatment such as a corona treatment or a surfactant treatment in order to enhance adhesion with fine particles having a heat resistant temperature of 150 ° C. or higher.
  • a surface treatment such as a corona treatment or a surfactant treatment in order to enhance adhesion with fine particles having a heat resistant temperature of 150 ° C. or higher.
  • the diameter of the fibrous material may be equal to or less than the thickness of the heat resistant porous membrane, but is preferably 0.01 to 5 ⁇ m, for example. If the diameter is too large, the entanglement between the fibrous materials will be insufficient, and for example, the effect of improving the strength of the heat-resistant porous membrane by using the fibrous materials may be reduced. On the other hand, if the diameter is too small, the pores of the heat-resistant porous membrane become too small and the ion permeability tends to decrease, and the effect of improving the output characteristics of the battery may be reduced.
  • the state of the presence of the fibrous material in the heat resistant porous membrane is, for example, preferably that the angle of the long axis (long axis) with respect to the heat resistant porous membrane surface is 30 ° or less on average, 20 More preferably, it is not more than 0 °.
  • the content of the fibrous material in the heat-resistant porous membrane is from the viewpoint of more effectively exerting the action due to the use of the fibrous material.
  • the total volume of the total solid content of the membrane is preferably 10% by volume or more, and more preferably 30% by volume or more.
  • the content of the fibrous material is preferably 85% by volume or less, and 70% by volume or less in the total volume of the total solid content of the heat-resistant porous membrane. It is more preferable that
  • the shutdown function can be imparted to the heat resistant porous membrane of the present invention.
  • a heat-resistant porous film having a shutdown function for example, hot-melt fine particles that melt at 80 to 150 ° C., or swellable fine particles that swell by absorbing a nonaqueous electrolyte at a temperature of 80 to 150 ° C.
  • the method of containing can be adopted.
  • the shutdown function in the heat resistant porous membrane can be evaluated by, for example, an increase in resistance due to the temperature of the model cell. That is, a model cell including a positive electrode, a negative electrode, a heat-resistant porous membrane (integrated with one of the positive electrode and the negative electrode), and a non-aqueous electrolyte is manufactured, and the model cell is placed in a thermostatic bath. Hold and measure the internal resistance value of the model cell while raising the temperature at a rate of 5 ° C./minute, and measure the temperature at which the measured internal resistance value is at least 5 times that before heating (resistance value measured at room temperature). By measuring, this temperature can be evaluated as the shutdown temperature of the heat resistant porous membrane.
  • Heat-melting fine particles that melt at 80 to 150 ° C. that is, fine particles having a melting temperature of 80 to 150 ° C. measured using a differential scanning calorimeter (DSC) in accordance with the provisions of Japanese Industrial Standard (JIS) K 7121
  • DSC differential scanning calorimeter
  • JIS Japanese Industrial Standard
  • the shutdown temperature of the separator evaluated by the increase in internal resistance is not less than the melting point of the heat-meltable fine particles and not more than 150 ° C.
  • the melting point (the melting temperature) of the heat-meltable fine particles is more preferably 140 ° C. or lower.
  • the constituent material of the heat-meltable fine particles include polyethylene (PE), copolymerized polyolefin having a structural unit derived from ethylene of 85 mol% or more, PP, or a polyolefin derivative (chlorinated polyethylene, chlorinated polypropylene, etc.), polyolefin Examples thereof include wax, petroleum wax, carnauba wax and the like.
  • the copolymer polyolefin include an ethylene-vinyl monomer copolymer, more specifically, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer, or an ethylene-ethyl acrylate copolymer. it can.
  • the heat-meltable fine particles may have only one kind of these constituent materials, or may have two or more kinds.
  • PE polyolefin wax, or EVA having a structural unit derived from ethylene of 85 mol% or more is preferable.
  • the heat-meltable fine particles may contain various known additives (for example, antioxidants) added to the resin as necessary, in addition to the above-described constituent materials. Absent.
  • the particle diameter of the heat-meltable fine particles is a number average particle diameter measured by the same measurement method as that of the fine particles having the heat-resistant temperature of 150 ° C. or more, and is preferably 0.001 ⁇ m or more, for example, 0.1 ⁇ m or more. More preferably, it is preferably 15 ⁇ m or less, and more preferably 1 ⁇ m or less.
  • a heat-resistant porous membrane having swellable fine particles that swell by absorbing a non-aqueous electrolyte at a temperature of 80 to 150 ° C. the swellable fine particles do not form a non-aqueous electrolyte when exposed to high temperatures in the battery.
  • Li ion in the heat-resistant porous membrane by absorbing and expanding greatly hereinafter referred to as “heat-swelling”. Therefore, the internal resistance of the battery is increased, and the shutdown function can be reliably ensured.
  • swellable fine particles having thermal swellability examples include crosslinked polystyrene (PS), crosslinked acrylic resin [for example, crosslinked polymethyl methacrylate (PMMA)], and crosslinked fluororesin [for example, crosslinked polyvinylidene fluoride (PVDF). ] Is preferred, and cross-linked PMMA is particularly preferred.
  • the particle diameter of the swellable fine particles is a number average particle diameter measured by dispersing the fine particles in a non-swelling medium (for example, water) using a laser scattering particle size distribution analyzer (for example, “LA-920” manufactured by HORIBA). It is preferably 1 to 20 ⁇ m.
  • cross-linked PMMA As commercially available products of swellable fine particles, for example, cross-linked PMMA “Gantz Pearl (product name)” manufactured by Ganz Kasei Co., Ltd., and cross-linked PMMA “RSP1079 (product name)” manufactured by Toyo Ink Co., Ltd. are available.
  • the heat-resistant porous membrane may contain only hot-melt fine particles, may contain only swellable fine particles, or contain both hot-melt fine particles and swellable fine particles. May be. Also, composite fine particles of a constituent material of a heat-fusible fine particle and a constituent material of a swellable fine particle such as a core-shell type fine particle having a swellable fine particle as a core and the surface thereof covered with the constituent material of a heat-fusible fine particle You may make it contain in a heat resistant porous membrane.
  • a heat-resistant porous film contains a heat-meltable fine particle or a swellable fine particle to provide a shutdown function
  • the heat-meltable fine particle or swelling in the heat-resistant porous film is required to ensure a good shutdown function.
  • Content of heat-soluble fine particles (when the heat-resistant porous film contains both heat-meltable fine particles and swellable fine particles, the total amount thereof is obtained.
  • the amount of the heat-meltable fine particles or the swellable fine particles in the heat-resistant porous membrane is the same hereinafter.) Is the total solid content of the heat-resistant porous membrane.
  • the total volume is preferably 5 to 70% by volume.
  • the content of these fine particles is too small, the shutdown effect due to the inclusion of these may be reduced, and if too large, the heat resistant temperature in the heat-resistant porous membrane is fine particles or fibrous materials having a heat resistance temperature of 150 ° C. or higher. Therefore, the effect secured by these may be reduced.
  • heat resistant porous membrane of the present invention include the following embodiments (a), (b) and (c).
  • B Sheet-like heat-resistant formed by uniformly dispersing fine particles having a heat-resistant temperature of 150 ° C. or more and fibrous materials (and, if necessary, other fine particles) and binding them with an organic binder. Porous membrane.
  • C A material in which a large number of fibrous materials are aggregated to form a sheet-like material only, for example, a woven fabric or a nonwoven fabric (including paper) is used. Heat-resistant porous material composed of a single layer composed of fine particles having a temperature of 150 ° C. or higher and other fine particles as necessary, and binding the fibrous material related to the sheet-like material and various fine particles with an organic binder film.
  • Such a heat-resistant porous membrane is integrated with an electrode (positive electrode and / or negative electrode) used in a nonaqueous battery, and used as a separator for separating the positive electrode and the negative electrode.
  • the heat-resistant temperature is 150 ° C. or more.
  • an organic binder and, if necessary, a fibrous material and other fine particles are dispersed in a solvent (including a dispersion medium; the same shall apply hereinafter) to prepare a heat-resistant porous film-forming composition.
  • the organic binder may be dissolved in a solvent may be used), and this may be applied to the electrode surface and dried to directly form a heat resistant porous film on the electrode surface.
  • the heat-resistant porous film-forming composition is applied to a substrate such as a PET film or a metal plate, and dried to form the heat-resistant porous film of the aspect (a) or (b). After being peeled from the substrate, it may be superposed on the electrode and integrated with the electrode by a roll press or the like.
  • a fibrous sheet-like material is impregnated with the heat-resistant porous film-forming composition, and an unnecessary composition is passed through a certain gap. After removing the matter, it can be dried to obtain an independent heat-resistant porous membrane.
  • the heat-resistant porous film is then overlapped with the electrode and integrated with the electrode by a roll press or the like.
  • Examples of the fibrous sheet used in the heat-resistant porous membrane of the aspect (c) include a woven fabric composed of at least one fibrous substance containing the above-mentioned exemplified materials as constituent components, and these Examples thereof include a porous sheet such as a nonwoven fabric having a structure in which fibrous materials are entangled with each other. More specifically, non-woven fabrics such as paper, PP non-woven fabric, polyester non-woven fabric (PET non-woven fabric, PEN non-woven fabric, PBT non-woven fabric, etc.) and PAN non-woven fabric can be exemplified.
  • non-woven fabrics such as paper, PP non-woven fabric, polyester non-woven fabric (PET non-woven fabric, PEN non-woven fabric, PBT non-woven fabric, etc.) and PAN non-woven fabric can be exemplified.
  • the solvent used in the composition for forming a heat-resistant porous film can uniformly disperse fine particles having a heat-resistant temperature of 150 ° C. or more, heat-meltable fine particles, swellable fine particles, and can uniformly dissolve or disperse the organic binder.
  • Any organic solvent may be used, for example, aromatic hydrocarbons such as toluene; furans such as tetrahydrofuran; ketones such as methyl ethyl ketone and methyl isobutyl ketone;
  • alcohols ethylene glycol, propylene glycol, etc.
  • various propylene oxide glycol ethers such as monomethyl acetate may be appropriately added to these solvents.
  • the binder when the binder is water-soluble or used as an emulsion, water may be used as a solvent.
  • an alcohol methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.
  • the tension can also be controlled.
  • the solid content including fine particles having an heat resistant temperature of 150 ° C. or higher, an organic binder, hot melt fine particles, swellable fine particles, fibrous materials, etc., for example, 10 to 80 mass. % Is preferable.
  • the composition for forming a heat-resistant porous film is applied to the electrode surface or other
  • a coated film (coated film before drying) applied to the substrate surface or a sheet-like material impregnated with a heat-resistant porous film-forming composition these compositions may be shared.
  • a certain gap is passed through.
  • a high solid content concentration for example, 50-80 Mass% heat-resistant porous film-forming composition
  • fine particles having a heat-resistant temperature of 150 ° C. or higher various mixing / stirring devices such as dispersers, agitators, homogenizers, ball mills, attritors, jet mills, dispersions
  • Heat-resistant porous material prepared by dispersing in an organic solvent using an apparatus and adding and mixing organic binders (further, if necessary, fibrous materials, heat-meltable fine particles, swellable fine particles, etc.).
  • a method of using a composition for forming a membrane; using fine particles having a heat resistance of 150 ° C. or higher, which is modified by applying a dispersing agent such as fats and oils, surfactants, and silane coupling agents on the surface Using a composition for forming a heat-resistant porous film prepared by using a composition for forming a heat-resistant porous film prepared using a combination of fine particles having a heat-resistant temperature of 150 ° C.
  • Method for controlling the drying conditions after impregnating the composition for forming a heat-resistant porous film into a sheet or coating on a substrate; pressurizing or heat-pressing the heat-resistant porous film A method of pressing; a method of impregnating a heat-resistant porous film-forming composition into a sheet-like material, or applying a magnetic field before drying after coating on a substrate; and the like can be employed. It may be carried out alone or in combination of two or more methods.
  • the thickness of the heat-resistant porous membrane thus obtained is preferably 3 ⁇ m or more, for example, from the viewpoint of further enhancing the short-circuit prevention effect of the battery in which it is used and increasing the strength of the heat-resistant porous membrane. More preferably.
  • the thickness of the heat-resistant porous film is preferably 50 ⁇ m or less, and more preferably 30 ⁇ m or less.
  • the porosity of the heat resistant porous membrane is preferably 20% or more in a dry state in order to secure the liquid retention amount of the nonaqueous electrolyte and improve the ion permeability, and preferably 30% More preferably.
  • the porosity of the heat resistant porous membrane is preferably 70% or less in a dry state, and is 60% or less. More preferably.
  • the porosity of the heat-resistant porous membrane: P (%) is calculated from the thickness of the heat-resistant porous membrane, the mass per area, and the density of the constituent components for each component i using the following formula (2). It can be calculated by calculating the sum.
  • the heat shrinkage rate at 150 ° C. (heat shrinkage rate in an integrated state with the electrode) of the heat-resistant porous membrane obtained by the method described in the examples below is preferably 5% or less.
  • the strength of the heat resistant porous membrane is desirably 50 g or more in terms of puncture strength using a needle having a diameter of 1 mm. If the piercing strength is too small, there is a possibility that a short circuit occurs due to the piercing of the heat-resistant porous film when lithium dendrite crystals are generated.
  • the air permeability of the heat-resistant porous membrane is measured by a method according to JIS P 8117, and is a Gurley value indicated by the number of seconds that 100 ml of air permeates the membrane under a pressure of 0.879 g / mm 2. 10 to 300 sec is desirable. If the air permeability is too high, the ion permeability is reduced, and if it is too low, the strength of the heat resistant porous membrane may be reduced.
  • the heat shrinkage rate, strength, and air permeability described above can be ensured by using the heat-resistant porous membrane having the configuration described so far.
  • the separator for non-aqueous batteries of the present invention is a separator having a multilayer structure in which a porous substrate and the heat-resistant porous membrane of the present invention are integrated.
  • porous base material related to the separator a resin nonwoven fabric, woven fabric, microporous film, or the like can be used.
  • thermoplastic resin having a melting point of 80 to 150 ° C. As the constituent resin of the porous substrate, thermoplastic resin having a melting point of 80 to 150 ° C. include various thermoplastic resins exemplified above as the constituent resin of the heat-meltable fine particles.
  • porous substrates composed of such thermoplastic resins microporous membranes made of polyolefin (PE, ethylene-propylene copolymer, etc.) are preferable.
  • the shutdown function in the separator of the present invention can also be evaluated by the resistance increase due to the temperature of the model cell, similar to the shutdown function of the heat-resistant porous film. That is, a model cell including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte is prepared, and the model cell is held in a thermostatic bath, and the internal resistance value of the model cell is set while increasing the temperature at a rate of 5 ° C./min. By measuring and measuring the temperature at which the measured internal resistance value is at least five times that before heating (resistance value measured at room temperature), this temperature can be evaluated as the shutdown temperature of the separator.
  • a porous substrate made of a heat resistant resin can be used.
  • a heat-resistant resin any resin that has a heat-resistant temperature of 150 ° C. or more, is stable with respect to the nonaqueous electrolyte used in the battery, and is stable with respect to the oxidation-reduction reaction inside the battery. Good. More specifically, heat-resistant resins such as polyimide, polyamideimide, aramid, polytetrafluoroethylene, polysulfone, polyurethane, PAN, polyester (PET, PBT, PEN, etc.) can be mentioned.
  • an ion-permeable porous film produced by a solvent extraction method, a dry or wet stretching (uniaxial or biaxial stretching) method, or the like can be used.
  • a film microporous by a foaming method using a drug, supercritical CO 2 or the like can also be used.
  • the step of applying the heat-resistant porous film forming composition used in the formation of the heat-resistant porous film to the surface of the porous substrate and drying it is performed. Then, the method of forming the layer which consists of a heat resistant porous film on the surface of a porous base material is employable. Further, the heat-resistant porous film obtained by the method for forming the heat-resistant porous film of the independent film exemplified above and the porous base material may be stacked and integrated by a roll press or the like.
  • the orientation of the plate-like particles is increased in the heat-resistant porous film.
  • various methods exemplified above can be used.
  • the heat-resistant porous membrane and the porous substrate do not have to be one each, and a plurality of separators may be configured.
  • positioned the porous base material on both surfaces of a heat resistant porous film or the structure which has arrange
  • the thickness of the separator is increased, which may increase the internal resistance of the battery and decrease the energy density.
  • the total number of the heat-resistant porous membrane and the porous substrate is preferably 5 or less.
  • the thickness is, for example, 5.5 ⁇ m or more from the viewpoint of further enhancing the short-circuit preventing effect of the battery, ensuring the strength of the separator, and improving its handleability.
  • the thickness is 10 ⁇ m or more.
  • the thickness of the separator is preferably 50 ⁇ m or less, and more preferably 30 ⁇ m or less.
  • the thickness of the heat-resistant porous film is X ( ⁇ m) and the thickness of the porous substrate is Y ( ⁇ m)
  • the ratio Y / X of X to Y is 1 to 20
  • Y / X is too large, the heat-resistant porous film becomes too thin, and, for example, when a porous substrate having poor dimensional stability at high temperatures is used, the effect of suppressing the thermal shrinkage becomes small. There is a fear.
  • the thickness X is the total thickness
  • the thickness Y is the total thickness
  • the thickness of the porous substrate is preferably 5 ⁇ m or more, and 30 ⁇ m or less. Is preferred.
  • the thickness of the heat resistant porous membrane is preferably 0.5 ⁇ m or more, more preferably 1 ⁇ m or more, More preferably, it is 2 ⁇ m or more, preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, and further preferably 3 ⁇ m or less.
  • the porosity of the separator obtained by using the above formula (2), where m is the mass per unit area (g / cm 2 ) of the separator and t is the thickness (cm) of the separator, is the retention of the non-aqueous electrolyte.
  • m is the mass per unit area (g / cm 2 ) of the separator and t is the thickness (cm) of the separator
  • the porosity of the separator obtained by the above method is preferably 70% or less and more preferably 60% or less in a dry state. .
  • m is the mass per unit area (g / cm 2 ) of the porous substrate
  • t is the porous substrate according to the separator that is required as the thickness (cm) of the porous substrate.
  • the porosity of the material is preferably 30 to 70%.
  • the porosity of the heat-resistant porous film related to the separator obtained by the above formula (2) is 20% or more (more preferably 30%) as in the case of the heat-resistant porous film integrated with the electrode. Above), 70% or less (more preferably 60% or less).
  • the thermal shrinkage rate at 150 ° C. of the separator obtained by the method shown in the examples below is 5% or less.
  • the strength of the separator is preferably 50 g or more in terms of piercing strength using a needle having a diameter of 1 mm. If the piercing strength is too low, a short circuit may occur due to the breakthrough of the separator when lithium dendrite crystals are generated.
  • the air permeability of the separator is measured by a method according to JIS P 8117, and is 100 to 300 sec as a Gurley value indicated by the number of seconds that 100 ml of air passes through the membrane under a pressure of 0.879 g / mm 2. Is desirable. If the air permeability is too high, the ion permeability is reduced, and if it is too low, the strength of the separator may be reduced.
  • the Gurley value of the separator satisfies the relationship of the following formula (3).
  • Gs Gurley value of the separator
  • Ga Gurley value of the porous substrate
  • Gb Gurley value of the heat-resistant porous film
  • max ⁇ Ga, Gb ⁇ whichever is greater of Ga and Gb.
  • Gb is calculated
  • Gb Gs-Ga (4)
  • the 180 ° peel strength of the heat-resistant porous membrane is 0.6 N / It is preferably at least cm, and more preferably at least 1.0 N / cm.
  • the peel strength is a value measured by the following method.
  • a test piece having a width of 2 cm and a length of 5 cm is cut out from an integrated product of the heat-resistant porous membrane and the electrode, or a separator, and an adhesive tape is attached to a 2 cm ⁇ 2 cm region on the surface of the heat-resistant porous membrane.
  • the pressure-sensitive adhesive tape has a width of 2 cm and a length of about 5 cm, and is attached so that one end of the pressure-sensitive adhesive tape and one end of the heat-resistant porous membrane are aligned.
  • the end of the test piece opposite to the side where the adhesive tape was affixed and the end of the adhesive tape affixed to the test piece opposite the end affixed to the test piece Gripping and pulling at a pulling speed of 10 mm / min to measure the strength when the heat-resistant porous film is peeled off.
  • the nonaqueous battery of the present invention the heat-resistant porous membrane of the present invention is integrated with at least one of the positive electrode and the negative electrode and used as a separator to separate the counter electrode, or the separator of the present invention has a positive electrode and a negative electrode.
  • Any other configuration and structure may be used as long as it is used as a separating material, and non-aqueous batteries using a conventionally known non-aqueous electrolyte (non-aqueous primary batteries such as lithium primary batteries, lithium Various configurations and structures employed in non-aqueous secondary batteries such as secondary batteries can be applied. Below, the lithium secondary battery which is especially a main form among the non-aqueous batteries of this invention is demonstrated in detail.
  • Examples of the form of the lithium secondary battery include a cylindrical shape (such as a rectangular tube shape or a cylindrical shape) using a steel can or an aluminum can as an outer can. Moreover, it can also be set as the soft package battery which used the laminated film which vapor-deposited the metal as an exterior body.
  • the positive electrode is not particularly limited as long as it is a positive electrode used in a conventionally known lithium secondary battery, that is, a positive electrode containing an active material capable of occluding and releasing Li ions.
  • an active material lithium-containing transition metal oxide represented by Li 1 + x MO 2 ( ⁇ 0.1 ⁇ x ⁇ 0.1, M: Co, Ni, Mn, etc.); lithium manganese such as LiMn 2 O 4 Oxide; LiMn x M (1-x) O 2 in which part of Mn of LiMn 2 O 4 is substituted with another element; olivine type LiMPO 4 (M: Co, Ni, Mn, Fe); LiMn 0.5 Ni 0.5 O 2 ; Li (1 + a) Mn x Ni y Co (1-xy) O 2 ( ⁇ 0.1 ⁇ a ⁇ 0.1, 0 ⁇ x ⁇ 0.5, 0 ⁇ y ⁇ 0.
  • a known conductive additive carbon material such as carbon black
  • PVDF polyvinylidene fluoride
  • a metal foil such as aluminum, a punching metal, a net, an expanded metal, or the like can be used, but an aluminum foil having a thickness of 10 to 30 ⁇ m is usually preferably used.
  • the lead part on the positive electrode side is usually provided by leaving the exposed part of the current collector without forming the positive electrode mixture layer on a part of the current collector and forming the lead part at the time of producing the positive electrode.
  • the lead portion is not necessarily integrated with the current collector from the beginning, and may be provided by connecting an aluminum foil or the like to the current collector later.
  • the negative electrode is not particularly limited as long as it is a negative electrode used in a conventionally known lithium secondary battery, that is, a negative electrode containing an active material capable of occluding and releasing Li ions.
  • an active material capable of occluding and releasing Li ions for example, carbon that can occlude and release lithium, such as graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), and carbon fibers as active materials
  • MCMB mesocarbon microbeads
  • elements such as Si, Sn, Ge, Bi, Sb, In and alloys thereof, lithium-containing nitrides, compounds that can be charged and discharged at a low voltage close to lithium metal such as lithium-containing oxides, or lithium metal or lithium / An aluminum alloy can also be used as the negative electrode active material.
  • a negative electrode mixture obtained by appropriately adding a conductive additive (carbon material such as carbon black) or a binder such as PVDF to these negative electrode active materials, and a molded body (negative electrode mixture layer) using a current collector as a core material
  • a conductive additive carbon material such as carbon black
  • a binder such as PVDF
  • the current collector When a current collector is used for the negative electrode, a copper or nickel foil, a punching metal, a net, an expanded metal, or the like can be used as the current collector, but a copper foil is usually used.
  • the upper limit of the thickness is preferably 30 ⁇ m, and the lower limit is preferably 5 ⁇ m.
  • the negative electrode layer (including a layer having a negative electrode active material and a negative electrode mixture layer) is usually formed on a part of the current collector during the preparation of the negative electrode. Without leaving the exposed portion of the current collector, it is provided as a lead portion.
  • the lead portion on the negative electrode side is not necessarily integrated with the current collector from the beginning, and may be provided by connecting a copper foil or the like to the current collector later.
  • the electrode is formed by laminating the positive electrode and the negative electrode via the separator of the present invention, or integrating at least one of the positive electrode and the negative electrode with the heat-resistant porous membrane of the present invention, It can be used in the form of an electrode group having a laminated structure in which a positive electrode and a negative electrode are laminated so that this heat-resistant porous film is interposed, or an electrode group having a wound structure in which these are wound.
  • a separate separator for example, a conventionally known lithium secondary battery
  • the microporous membrane separator made of polyolefin used in the battery of (1) may be used, but since the heat-resistant porous membrane of the present invention functions as a separator (that is, a separator) separating the positive electrode and the negative electrode, There is no need to use a separator.
  • non-aqueous electrolyte a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in an organic solvent is used.
  • the lithium salt is not particularly limited as long as it dissociates in a solvent to form Li + ions and does not cause a side reaction such as decomposition in a voltage range used as a battery.
  • inorganic lithium salts such as LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 ; LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (2 ⁇ n ⁇ 7), LiN (R f OSO 2 ) 2 [where R f is a fluoroalkyl group]; Etc. can be used.
  • inorganic lithium salts such as LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 ; LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (2 ⁇
  • the organic solvent used in the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause side reactions such as decomposition in the voltage range used as a battery.
  • cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate
  • chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate
  • chain esters such as methyl propionate
  • cyclic esters such as ⁇ -butyrolactone
  • Chain ethers such as ethane, diethyl ether, 1,3-dioxolane, diglyme, triglyme and tetraglyme
  • cyclic ethers such as dioxane, tetrahydrofuran and 2-methyltetrahydrofuran
  • nitriles such as acetonitrile, propionitrile and methoxypropionitrile
  • Sulfites such as
  • ⁇ may be used in combination of two or more thereof.
  • a combination that can obtain high conductivity such as a mixed solvent of ethylene carbonate and chain carbonate.
  • vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexyl benzene, biphenyl, and fluorobenzene are used for the purpose of improving the safety, charge / discharge cycleability, and high-temperature storage properties of these non-aqueous electrolytes.
  • Additives such as t-butylbenzene can also be added as appropriate.
  • the concentration of this lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / l, more preferably 0.9 to 1.25 mol / l.
  • melting at room temperature such as ethyl-methylimidazolium trifluoromethylsulfonium imide, heptyl-trimethylammonium trifluoromethylsulfonium imide, pyridinium trifluoromethylsulfonium imide, guanidinium trifluoromethylsulfonium imide A salt can also be used.
  • a polymer material that gels the non-aqueous electrolyte may be added, and the non-aqueous electrolyte may be gelled and used for a battery.
  • Polymer materials for making non-aqueous electrolyte into a gel include PVDF, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), PAN, polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer
  • a known host polymer capable of forming a gel electrolyte such as a crosslinked polymer having an ethylene oxide chain in the main chain or side chain, and a crosslinked poly (meth) acrylate.
  • FIG. 1 is a cross-sectional view showing an example of the lithium secondary battery of the present invention.
  • a lithium secondary battery of the present invention includes a positive electrode 1 having a positive electrode mixture layer containing the positive electrode active material described above, a negative electrode 2 having a negative electrode mixture layer containing a negative electrode active material, and A separator 3 and a non-aqueous electrolyte 4 are provided.
  • the positive electrode 1 and the negative electrode 2 are spirally wound via a separator 3 and are housed in a cylindrical battery can 5 together with a nonaqueous electrolyte solution 4 as an electrode group having a wound structure.
  • the metal foil which is a current collector used for manufacturing the positive electrode 1 and the negative electrode 2 is not illustrated.
  • the separator 3 shows the cut surface, it does not attach
  • the battery can 5 is made of, for example, iron and nickel-plated on the surface, and an insulator 6 made of, for example, polypropylene is disposed at the bottom of the battery can 5 prior to the insertion of the electrode group having the wound structure.
  • the sealing plate 7 is made of, for example, aluminum and has a disk shape.
  • a thin portion 7a is provided at the center of the sealing plate 7, and a pressure introduction port 7b for allowing the battery internal pressure to act on the explosion-proof valve 9 around the thin portion 7a.
  • the protrusion part 9a of the explosion-proof valve 9 is welded to the upper surface of the thin part 7a, and the welding part 11 is comprised.
  • the thin-walled portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are shown only on the cut surface for easy understanding on the drawing, and the contour line behind the cut surface is not shown. is doing.
  • the welded portion 11 between the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 is also shown in an exaggerated state so as to facilitate understanding on the drawing.
  • the terminal plate 8 is made of, for example, rolled steel, has a nickel-plated surface, has a hat-like shape with a peripheral edge portion, and the terminal plate 8 is provided with a gas discharge port 8a.
  • the explosion-proof valve 9 is made of, for example, aluminum and has a disk shape.
  • a projecting portion 9a having a tip portion is provided on the power generation element side (lower side in FIG. 1) at the center, and the thin-walled portion 9b As described above, the lower surface of the protruding portion 9a is welded to the upper surface of the thin-walled portion 7a of the sealing plate 7 to form the welded portion 11.
  • the insulating packing 10 is made of, for example, polypropylene and has an annular shape.
  • the insulating packing 10 is arranged at the upper part of the peripheral edge of the sealing plate 7, and the explosion-proof valve 9 is arranged at the upper part thereof, so that the sealing plate 7 and the explosion-proof valve 9 are insulated. At the same time, the gap between the two is sealed so that the electrolyte does not leak from between them.
  • the annular gasket 12 is made of, for example, polypropylene.
  • the lead body 13 is made of aluminum, for example, and connects the sealing plate 7 and the positive electrode 1.
  • An insulator 14 is disposed on the upper part of the electrode group having a wound structure, and the negative electrode 2 and the bottom of the battery can 5 are connected by a lead body 15 made of nickel, for example.
  • the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are in contact with each other at the welded portion 11, and the peripheral portion of the explosion-proof valve 9 and the peripheral portion of the terminal plate 8 are in contact.
  • 1 and the sealing plate 7 are connected by a lead body 13 on the positive electrode side. Therefore, in a normal state, the positive electrode 1 and the terminal plate 8 are connected to the lead body 13, the sealing plate 7, the explosion-proof valve 9 and their welded parts.
  • the electrical connection is obtained by 11 and functions normally as an electric circuit.
  • the explosion-proof valve 9 When an abnormal situation occurs in the battery, such as the battery is exposed to high temperature or generates heat due to overcharge, and gas is generated inside the battery and the internal pressure of the battery increases, the explosion-proof valve 9 The center part of the is deformed in the internal pressure direction (the upper direction in FIG. 1). Along with this, a shearing force is applied to the thin portion 7a of the sealing plate 7 integrated at the welded portion 11, and the thin portion 7a is broken, or the projection 9a of the explosion-proof valve 9 and the thin portion 7a of the sealing plate 7 are broken.
  • the thin-walled portion 9b provided in the explosion-proof valve 9 is cleaved to discharge the gas from the gas discharge port 8a of the terminal plate 8 to the outside of the battery, thereby preventing the battery from bursting. Designed to be able to.
  • the non-aqueous battery of the present invention can be applied to the same uses as various uses in which non-aqueous batteries such as lithium secondary batteries known in the art are used.
  • Example 1 Provide of electrode> The positive electrode was produced as follows. First, 90 parts by mass of LiCoO 2 (positive electrode active material), which is a lithium-containing composite oxide, is mixed with 5 parts by mass of carbon black as a conductive additive, and PVDF: 5 parts by mass as a binder is added to NMP as a binder. The dissolved solution was added and mixed to obtain a positive electrode mixture-containing slurry, which was passed through a 70-mesh net to remove large particles.
  • LiCoO 2 positive electrode active material
  • carbon black as a conductive additive
  • PVDF 5 parts by mass as a binder
  • the negative electrode was produced as follows. Artificial graphite was used as the negative electrode active material, PVDF was used as the binder, these were mixed at a mass ratio of 95: 5, and NMP was added and mixed to obtain a negative electrode mixture-containing paste.
  • This negative electrode mixture-containing paste was uniformly applied to both sides of a negative electrode current collector made of a copper foil having a thickness of 10 ⁇ m and dried, and then compression-molded with a roll press machine to a total thickness of 100 ⁇ m. It cut
  • PNVA poly N-vinylacetamide
  • a PE microporous film (thickness 16 ⁇ m, porosity 40%, PE melting point 135 ° C.) with a corona discharge treatment on one side was used as a porous substrate, and the slurry was applied to the treated surface with a microgravure coater.
  • the separator was dried to form a heat-resistant porous film, thereby obtaining a separator having a thickness of 20 ⁇ m.
  • the volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 7.0% by volume, and the porosity of the heat resistant porous membrane was 48%.
  • the separator obtained as described above was stacked while being interposed between the positive electrode and the negative electrode so that the heat-resistant porous membrane side was directed to the positive electrode side, and wound to form a wound body electrode group.
  • the obtained wound electrode group was put into an iron battery can having a diameter of 18 mm and a height of 65 mm, and after injecting an electrolytic solution, sealing was performed to produce a lithium secondary battery.
  • the lithium secondary battery includes an explosion-proof valve at the top of the can for releasing the pressure when the internal pressure increases.
  • the design electric capacity when charged to 4.2 V (the positive electrode potential is 4.3 V with respect to Li) is 1400 mAh.
  • Example 2 4000 g of the same boehmite powder used in Example 1 was added to 4000 g of water in four portions, and the mixture was stirred with a disper at 2800 rpm for 5 hours to prepare a uniform dispersion. 400 g of an aqueous solution of PNVA (concentration: 10% by mass) as an organic binder was added to this dispersion, and water was further added and stirred at room temperature until uniformly dispersed to prepare a slurry having a solid content ratio of 30% by mass.
  • PNVA concentration: 10% by mass
  • a fluorosurfactant perfluoroalkylethylene oxide adduct
  • a fluorosurfactant perfluoroalkylethylene oxide adduct
  • the slurry was applied using a micro gravure coater, and then dried to form a heat resistant porous membrane, resulting in a thickness of 20 ⁇ m.
  • a separator was obtained.
  • the volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 2.5% by volume, and the porosity of the heat resistant porous membrane was 52%.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • Example 3 The heat resistance was the same as in Example 2 except that the fine particles having a heat resistance temperature of 150 ° C. or higher were changed to secondary particulate boehmite (average particle diameter 0.6 ⁇ m, specific surface area 15 m 2 / g) in which primary particles were continuous.
  • a slurry for forming a porous film was prepared.
  • a three-layer polyolefin microporous membrane (thickness 16 ⁇ m, porosity 40%, PE melting point 135 ° C.
  • the slurry was dried to form a heat-resistant porous film, thereby obtaining a separator having a thickness of 18 ⁇ m.
  • the volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 2.5% by volume, and the porosity of the heat resistant porous membrane was 55%.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • Example 4 To fine particles having a heat resistant temperature of 150 ° C. or higher, 4000 g of secondary particulate boehmite with the same primary particles as used in Example 3 was added to 4000 g of water in four portions, and 5 times at 2800 rpm with a disper. A uniform dispersion was prepared by stirring for a period of time. In this dispersion, an aqueous dispersion (solid content ratio: 40% by mass) of crosslinked PMMA fine particles (average particle size 0.4 ⁇ m), which are swellable fine particles that swell by absorbing a nonaqueous electrolytic solution at a temperature of 80 to 150 ° C.
  • the slurry was applied using a micro gravure coater and then dried to form a heat-resistant porous film.
  • a 20 ⁇ m separator was obtained.
  • the volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 4.8% by volume, and the porosity of the heat resistant porous membrane was 50%.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • Example 5 Use 4000 g of secondary particulate boehmite (average particle size 0.06 ⁇ m, specific surface area 100 m 2 / g) in which primary particles are connected to fine particles having a heat-resistant temperature of 150 ° C. or more, and add them to 4000 g of water in four portions. The mixture was stirred for 5 hours at 2800 rpm with a disper to prepare a uniform dispersion.
  • an aqueous dispersion solid content ratio 40 mass% of PE fine particles (melting point 135 ° C.) and 2100 g of an aqueous solution of PNVA (concentration 10 mass%) are added as hot-melt fine particles, and water is further added to the solid content ratio.
  • a slurry for forming a heat resistant porous film A nonwoven fabric made of PET (weighing 8 g / m 2 , thickness 16 ⁇ m) is used as a porous substrate, and the slurry is dip coated on the porous substrate and dried to form a heat-resistant porous film, thereby obtaining a separator having a thickness of 20 ⁇ m. It was.
  • the volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 6.2% by volume, and the porosity of the heat resistant porous membrane was 38%.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • Example 6 4000 g of alumina fine particles (average particle size 0.4 ⁇ m, specific surface area 7 m 2 / g) are used as fine particles having a heat resistance temperature of 150 ° C. or higher, and this is added to 4000 g of water in four portions, and stirred at 2800 rpm for 5 hours with a disper. And a uniform dispersion was prepared. To this dispersion, 4000 g of an aqueous dispersion (solid content ratio: 40% by mass) of PE fine particles (melting point: 135 ° C.) and 1600 g of an aqueous solution of PNVA (concentration: 10% by mass) are added as heat-meltable fine particles. The mixture was added so that the ratio was 30% by mass, and stirred until uniform to obtain a heat-resistant porous film forming slurry.
  • alumina fine particles average particle size 0.4 ⁇ m, specific surface area 7 m 2 / g
  • the slurry was applied on both surfaces of the same negative electrode as that prepared in Example 1 using a micro gravure coater to form a heat-resistant porous film having a thickness of 20 ⁇ m.
  • the volume ratio of the organic binder in the total volume of the total solid content of the heat-resistant porous film was 4.5% by volume, and the porosity of the heat-resistant porous film was 50%.
  • the negative electrode integrated with the heat-resistant porous membrane and the same positive electrode as that prepared in Example 1 were superposed and wound in a spiral shape to produce a wound electrode group.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this wound electrode group was used.
  • Example 7 The same heat-resistant porous film forming slurry as that prepared in Example 6 was applied on both surfaces of the same negative electrode as that prepared in Example 1 using a microgravure coater, and the heat-resistant porous film having a thickness of 10 ⁇ m. A membrane was formed. Further, the same heat-resistant porous film-forming slurry as that prepared in Example 6 was applied on both surfaces of the same positive electrode as that prepared in Example 1 using a microgravure coater, and the thickness was 10 ⁇ m. A porous film was formed.
  • a lithium secondary battery was produced in the same manner as in Example 6 except that the negative electrode integrated with the heat resistant porous membrane and the positive electrode integrated with the heat resistant porous membrane were used.
  • Example 1 A slurry for forming a heat-resistant porous film was prepared in the same manner as in Example 1 except that the amount of the aqueous solution of PNVA (concentration: 10% by mass) used as an organic binder was changed to 2000 g, and this slurry was used except that this slurry was used.
  • a separator was produced in the same manner as in Example 1. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 11% by volume, and the porosity of the heat resistant porous membrane was 42%.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • Example 2 A slurry for forming a heat-resistant porous film prepared in the same manner as in Example 1 except that boehmite particles (average particle size 0.005 ⁇ m, specific surface area 250 m 2 / g) were used as fine particles having a heat-resistant temperature of 150 ° C. or higher.
  • a separator was prepared in the same manner as in Example 1. However, since the filler of the heat resistant porous membrane was peeled off immediately, the battery was not manufactured.
  • Comparative Example 3 Use 4000 g of the same boehmite particles as those used in Comparative Example 2 for fine particles having a heat-resistant temperature of 150 ° C. or higher, add them to 4000 g of water in four portions, and stir the mixture at 2800 rpm for 5 hours with uniform dispersion. A liquid was prepared. To this dispersion, 4000 g of an aqueous solution of PNVA (concentration: 10% by mass) as an organic binder was added and stirred at room temperature until uniformly dispersed to prepare a slurry for forming a heat resistant porous film. And the separator was produced like Example 1 except having used this slurry. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 20% by volume, and the porosity of the heat resistant porous membrane was 38%.
  • PNVA concentration: 10% by mass
  • Example 2 Furthermore, a lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • the MD direction and the TD direction are each 5 cm. A strip-shaped sample piece of 10 cm was cut out.
  • the MD direction is the machine direction when producing an integrated product of the separator or heat-resistant porous membrane and the negative electrode
  • the TD direction is a direction perpendicular to them.
  • the heat shrinkage rate of each separator and the heat resistant porous film was set to the larger one of the heat shrinkage rate in the long side direction and the heat shrinkage rate in the short side direction.
  • Table 1 shows the results of the above evaluations excluding safety evaluation.
  • the lithium secondary batteries of Examples 1 to 7 having a heat-resistant porous film with an appropriate organic binder volume ratio have good output characteristics.
  • the separators used in the lithium secondary batteries of Examples 1 to 5 and the heat-resistant porous membrane used in the lithium secondary batteries of Examples 6 and 7 have a low thermal shrinkage at 150 ° C.
  • the lithium secondary batteries of Examples 1 to 7 that use Pt suppress the occurrence of short circuits due to thermal contraction of separators and separators (heat-resistant porous membrane integrated with electrodes) even when the temperature inside the batteries becomes high. As shown in the safety evaluation, it has good safety.
  • the lithium secondary batteries of Comparative Examples 1 and 3 having a heat-resistant porous film in which the volume ratio of the organic binder is too large are inferior in output characteristics to the batteries of the examples.

Abstract

Disclosed is a separator for a non-aqueous battery, characterized by comprising a porous base material and a heat-resistant porous film integrated with each other, wherein the heat-resistant porous film comprises microparticles having an upper temperature limit of 150˚C or higher and an organic binder, and wherein the microparticles have an average particle diameter of 0.01-10 μm, the heat-resistant porous film contains the organic binder at a content ratio of 7 vol% or less relative to the total amount of the solid contents. Also disclosed is a non-aqueous battery characterized by being equipped with the heat-resistant porous film or the separator.

Description

非水電池用セパレータおよび非水電池Nonaqueous battery separator and nonaqueous battery
　本発明は、非水電池において、正極と負極とを仕切る隔離材に適用するのに好適な耐熱性多孔質膜、該耐熱性多孔質膜を用いた非水電池用セパレータ、および前記耐熱性多孔質膜または前記非水電池用セパレータを有し、出力特性および安全性に優れた非水電池に関するものである。 The present invention relates to a heat-resistant porous membrane suitable for application to a separator separating a positive electrode and a negative electrode in a non-aqueous battery, a separator for a non-aqueous battery using the heat-resistant porous membrane, and the heat-resistant porous membrane. The present invention relates to a nonaqueous battery having a membrane or the separator for a nonaqueous battery and having excellent output characteristics and safety.
　非水電池の一種であるリチウム二次電池は、エネルギー密度が高いという特徴から、携帯電話やノート型パーソナルコンピューターなどの携帯機器の電源として広く用いられている。更に近年は、高エネルギー密度という特性を活かして、電動アシスト自転車、電動バイク、電気自動車、ハイブリッド自動車といった車載用の電源としての適用も検討されている。このような車載用途の電源は、携帯機器の電源と比べて容量が大きいため、更なる安全性確保が重要である。一方で、要求される出力も携帯機器の電源に比べて大きいため、出力特性を劣化させない安全化技術が要求されている。 A lithium secondary battery, which is a type of non-aqueous battery, is widely used as a power source for portable devices such as mobile phones and notebook personal computers because of its high energy density. Further, in recent years, taking advantage of the characteristic of high energy density, application as an in-vehicle power source such as an electric assist bicycle, an electric motorcycle, an electric vehicle, and a hybrid vehicle has been studied. Since such a power source for in-vehicle use has a larger capacity than a power source for portable devices, it is important to ensure further safety. On the other hand, since the required output is larger than the power supply of the portable device, a safety technology that does not deteriorate the output characteristics is required.
　現行のリチウム二次電池では、正極と負極の間に介在させるセパレータとして、例えば厚みが２０～３０μｍ程度のポリオレフィン系の微多孔性フィルム（微多孔膜）が使用されている。また、セパレータの素材としては、電池の異常発熱温度以下でセパレータの構成樹脂を溶融させて空孔を閉塞させ、これにより電池の内部抵抗を上昇させて短絡の際などに電池の安全性を向上させる所謂シャットダウン効果を確保するため、ポリエチレンなどのポリオレフィンの中でも融点の低い材料が適用されることがある。 In current lithium secondary batteries, a polyolefin microporous film (microporous film) having a thickness of about 20 to 30 μm is used as a separator interposed between a positive electrode and a negative electrode. In addition, as separator material, the constituent resin of the separator is melted below the abnormal heat generation temperature of the battery to close the pores, thereby increasing the internal resistance of the battery and improving the safety of the battery in the event of a short circuit. In order to ensure a so-called shutdown effect, a material having a low melting point may be used among polyolefins such as polyethylene.
　ところで、こうしたセパレータとしては、例えば、多孔化と強度向上のために一軸延伸または二軸延伸したフィルムが用いられている。このようなセパレータは、単独で存在する膜として供給されるため、作業性などの点で一定の強度が要求され、これを前記延伸によって確保している。しかし、このような延伸フィルムでは結晶化度が増大しており、シャットダウン温度も、電池の異常発熱温度に近い温度にまで高まっているため、電池の安全性確保のためのマージンが十分とは言い難い。 By the way, as such a separator, for example, a uniaxially stretched film or a biaxially stretched film is used for increasing the porosity and improving the strength. Since such a separator is supplied as a single film, a certain strength is required in terms of workability and the like, and this is secured by the stretching. However, such a stretched film has increased crystallinity, and the shutdown temperature has increased to a temperature close to the abnormal heat generation temperature of the battery, so that the margin for ensuring the safety of the battery is not sufficient. hard.
　また、前記延伸によってフィルムにはひずみが生じており、これが高温に曝されると、残留応力によって収縮が起こるという問題がある。収縮温度は、融点、すなわちシャットダウン温度と非常に近いところに存在する。このため、ポリオレフィン系の微多孔性フィルムセパレータを使用するときには、充電異常時などにより電池の温度がシャットダウン温度に達すると、電流を直ちに減少させて電池の温度上昇を防止しなければならない。空孔が十分に閉塞せず電流を直ちに減少できなかった場合には、電池の温度は容易にセパレータの収縮温度にまで上昇するため、内部短絡による異常発熱の危険性があるからである。 In addition, the film is distorted by the stretching, and when it is exposed to high temperature, there is a problem that shrinkage occurs due to residual stress. The shrinkage temperature is very close to the melting point, ie the shutdown temperature. For this reason, when the polyolefin microporous film separator is used, if the battery temperature reaches the shutdown temperature due to abnormal charging or the like, the current must be immediately reduced to prevent the battery temperature from rising. This is because if the pores are not sufficiently closed and the current cannot be reduced immediately, the battery temperature easily rises to the shrinkage temperature of the separator, and there is a risk of abnormal heat generation due to an internal short circuit.
　このようなセパレータの熱収縮による短絡を防止し、電池の信頼性を高める技術として、例えば、耐熱性の良好な多孔質基材と、フィラー粒子と、シャットダウン機能を確保するための樹脂成分とを有するセパレータにより電気化学素子を構成することが提案されている（特許文献１～３）。 As a technique for preventing such a short circuit due to thermal contraction of the separator and improving the reliability of the battery, for example, a porous base material having good heat resistance, filler particles, and a resin component for ensuring a shutdown function It has been proposed to form an electrochemical element with a separator having the above (Patent Documents 1 to 3).
　また、ポリオレフィン製の多孔質膜に耐熱性樹脂や無機微粒子などを主体とした耐熱層を形成して、耐熱性を高めることが提案されている（特許文献４～６）。 Further, it has been proposed to increase heat resistance by forming a heat-resistant layer mainly composed of heat-resistant resin or inorganic fine particles on a polyolefin porous film (Patent Documents 4 to 6).
　特許文献１～６に開示の技術によれば、電池の異常時の際にも異常発熱が生じ難い安全性に優れた電池を提供することができる。 According to the technologies disclosed in Patent Documents 1 to 6, it is possible to provide a battery with excellent safety that is unlikely to generate abnormal heat even when the battery is abnormal.
国際公開第２００６／６２１５３号International Publication No. 2006/62153 特表２００５－５３６８５８号公報JP 2005-536858 gazette 国際公開第２００９／４４７４１号International Publication No. 2009/44741 特開２０００－３０６８６号公報JP 2000-30686 A 特開２００８－３００３６２号公報JP 2008-300362 A 特表２００８－５２４８２４号公報Special table 2008-524824
　ところで、リチウム二次電池を例えば車載用途に適用する場合には、安全性と同時に高い出力特性が要求される。 By the way, when a lithium secondary battery is applied to, for example, an on-vehicle application, high output characteristics are required simultaneously with safety.
　本発明は、前記事情に鑑みてなされたものであり、高い安全性と高い出力特性とを有する非水電池、正極と負極との隔離材として機能でき、前記非水電池を構成可能な耐熱性多孔質膜、および前記非水電池を構成可能なセパレータを提供する。 The present invention has been made in view of the above circumstances, and can be used as a nonaqueous battery having high safety and high output characteristics, a separator between a positive electrode and a negative electrode, and heat resistance capable of constituting the nonaqueous battery. A porous membrane and a separator capable of constituting the nonaqueous battery are provided.
　本発明の非水電池用セパレータは、多孔質基材と、耐熱性多孔質膜とが、一体化している非水電池用セパレータであって、前記耐熱性多孔質膜は、耐熱温度が１５０℃以上の微粒子と、有機バインダとを含み、前記微粒子の平均粒子径が、０．０１～１０μｍであり、前記耐熱性多孔質膜の全固形分中に占める前記有機バインダの割合が、７体積％以下であることを特徴とする。 The separator for a non-aqueous battery according to the present invention is a separator for a non-aqueous battery in which a porous substrate and a heat-resistant porous membrane are integrated, and the heat-resistant porous membrane has a heat-resistant temperature of 150 ° C. Including the fine particles and an organic binder, the fine particles have an average particle diameter of 0.01 to 10 μm, and the proportion of the organic binder in the total solid content of the heat-resistant porous film is 7% by volume. It is characterized by the following.
　また、本発明の第１の非水電池は、正極、負極、耐熱性多孔質膜および非水電解質を含む非水電池であって、前記耐熱性多孔質膜と、前記正極および前記負極から選ばれる少なくとも一方とが、一体化しており、前記耐熱性多孔質膜は、耐熱温度が１５０℃以上の微粒子と、有機バインダとを含み、前記微粒子の平均粒子径が、０．０１～１０μｍであり、前記耐熱性多孔質膜の全固形分中に占める前記有機バインダの割合が、７体積％以下であることを特徴とする。 The first nonaqueous battery of the present invention is a nonaqueous battery including a positive electrode, a negative electrode, a heat resistant porous membrane and a nonaqueous electrolyte, and is selected from the heat resistant porous membrane, the positive electrode and the negative electrode. And the heat-resistant porous membrane contains fine particles having a heat-resistant temperature of 150 ° C. or higher and an organic binder, and the average particle diameter of the fine particles is 0.01 to 10 μm. The ratio of the organic binder in the total solid content of the heat-resistant porous membrane is 7% by volume or less.
　また、本発明の第２の非水電池は、正極、負極、セパレータおよび非水電解質を含む非水電池であって、前記セパレータが、多孔質基材と、耐熱性多孔質膜とが、一体化しており、前記耐熱性多孔質膜は、耐熱温度が１５０℃以上の微粒子と、有機バインダとを含み、前記微粒子の平均粒子径が、０．０１～１０μｍであり、前記耐熱性多孔質膜の全固形分中に占める前記有機バインダの割合が、７体積％以下であることを特徴とする。 The second non-aqueous battery of the present invention is a non-aqueous battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the separator is formed by integrating a porous substrate and a heat-resistant porous film. The heat-resistant porous film includes fine particles having a heat-resistant temperature of 150 ° C. or more and an organic binder, and the fine particles have an average particle diameter of 0.01 to 10 μm, and the heat-resistant porous film The ratio of the organic binder in the total solid content of is 7% by volume or less.
　本発明によれば、高い安全性と高い出力特性とを有する非水電池、正極と負極との隔離材として機能でき、前記非水電池を構成可能な耐熱性多孔質膜、および前記非水電池を構成可能なセパレータを提供することができる。 According to the present invention, a non-aqueous battery having high safety and high output characteristics, a heat-resistant porous membrane capable of functioning as a separator between a positive electrode and a negative electrode and constituting the non-aqueous battery, and the non-aqueous battery Can be provided.
図１は、本発明のリチウム二次電池の一例を示す断面図である。FIG. 1 is a cross-sectional view showing an example of the lithium secondary battery of the present invention.
　先ず、本発明の耐熱性多孔質膜について説明する。本発明の耐熱性多孔質膜は、耐熱温度が１５０℃以上の微粒子と、有機バインダとを少なくとも含有するものであり、非水電池において、正極と負極とを仕切る隔離材として好適なものである。 First, the heat resistant porous membrane of the present invention will be described. The heat-resistant porous membrane of the present invention contains at least a fine particle having a heat-resistant temperature of 150 ° C. or higher and an organic binder, and is suitable as a separator for partitioning the positive electrode and the negative electrode in a non-aqueous battery. .
　すなわち、本発明の耐熱性多孔質膜は、例えば非水電池の正極および負極のうちの少なくとも一方と一体化されることで、前記非水電池内において、正極と負極とを隔離するセパレータとして作用したり、多孔質基材と一体化されることで、独立膜としての非水電池用セパレータを構成したりするものである。 That is, the heat-resistant porous membrane of the present invention acts as a separator that separates the positive electrode and the negative electrode in the non-aqueous battery, for example, by being integrated with at least one of the positive electrode and the negative electrode of the non-aqueous battery. Or a non-aqueous battery separator as an independent film by being integrated with a porous substrate.
　本発明の耐熱性多孔質膜においては、全固形分の全体積（空孔部分を除く耐熱性多孔質膜の構成成分の全体積。以降に記載する耐熱性多孔質膜およびセパレータにおける「全固形分の全体積」について、同じである。）中に占める有機バインダの体積の割合を、７体積％以下とする。耐熱性多孔質膜における有機バインダの割合を前記のように小さくすることで、空孔が有機バインダによって塞がれることを防止して、耐熱性多孔質膜におけるイオン透過性を高め、この耐熱性多孔質膜を用いた電池の出力特性を高めることができる。前記の効果をより良好に確保する観点から、耐熱性多孔質膜の全固形分中に占める有機バインダの割合は、５体積％以下であることが好ましく、３体積％以下であることがより好ましく、１体積％以下であることが更に好ましい。特に、後述する、分子内にアミド基を有する有機バインダ、中でもＮ－ビニルアセトアミドの単独重合体や共重合体では、前記微粒子を結着する場合にその割合が多いと、形成される多孔質膜の柔軟性が低下して電極の巻回などが困難になる場合があり、耐熱性多孔質膜の柔軟性付与の観点からも、有機バインダの割合はできるだけ少なくすることが望ましい。 In the heat resistant porous membrane of the present invention, the total volume of all solids (total volume of components of the heat resistant porous membrane excluding the voids. The same applies to the “total volume of the minute.”) The ratio of the volume of the organic binder in the volume is 7% by volume or less. By reducing the ratio of the organic binder in the heat-resistant porous film as described above, the pores are prevented from being blocked by the organic binder, and the ion permeability in the heat-resistant porous film is increased, and this heat resistance The output characteristics of the battery using the porous membrane can be enhanced. From the viewpoint of ensuring the above effects better, the proportion of the organic binder in the total solid content of the heat-resistant porous membrane is preferably 5% by volume or less, more preferably 3% by volume or less. More preferably, it is 1 volume% or less. In particular, in an organic binder having an amide group in the molecule, which will be described later, especially a homopolymer or copolymer of N-vinylacetamide, a porous film is formed when the proportion of the fine particles is large. Therefore, it is desirable to reduce the proportion of the organic binder as much as possible from the viewpoint of imparting flexibility to the heat-resistant porous film.
　ただし、耐熱性多孔質膜における有機バインダの割合が小さすぎると、例えば耐熱温度が１５０℃以上の微粒子同士を結着する力が弱くなって、耐熱性多孔質膜から前記微粒子が脱落しやすくなったり、また、耐熱性多孔質膜が電極や多孔質基材から剥離しやすくなったりする。よって、耐熱性多孔質膜の全固形分中に占める有機バインダの割合は、０．５体積％以上であることが好ましい。 However, if the proportion of the organic binder in the heat-resistant porous film is too small, for example, the force for binding fine particles having a heat-resistant temperature of 150 ° C. or higher becomes weak, and the fine particles are likely to fall off from the heat-resistant porous film. In addition, the heat-resistant porous film may be easily peeled off from the electrode and the porous substrate. Therefore, the proportion of the organic binder in the total solid content of the heat resistant porous membrane is preferably 0.5% by volume or more.
　有機バインダとしては、耐熱性多孔質膜中の成分同士や、耐熱性多孔質膜と多孔質基材や電極とを良好に結着でき、更に電気化学的に安定で、かつ電池の有する非水電解質（非水電解液）に対して安定であれば特に制限はないが、引張強度や引張弾性率が高いことに加えて、耐熱温度が１５０℃以上の微粒子との接着性が良好であることから、分子内にアミド基（アミド結合）を有するものが好ましく、下記一般式（１）で表されるモノマー由来の構造単位を含んでいるものがより好ましい。下記一般式（１）で表されるモノマーを用いて重合体を形成した場合、炭素－炭素二重結合の部分が開裂して主鎖を形成する。よって、下記一般式（１）で表されるモノマー由来の構造単位を含む有機バインダにおいては、アミド基を含む部分［－ＮＲ３－（Ｃ＝Ｏ）－Ｒ２］を側鎖に有するものとなる。 As the organic binder, the components in the heat-resistant porous film, the heat-resistant porous film and the porous substrate or electrode can be satisfactorily bonded, and are electrochemically stable and non-aqueous There is no particular limitation as long as it is stable with respect to the electrolyte (non-aqueous electrolyte), but in addition to high tensile strength and tensile modulus, it has good adhesion to fine particles with a heat resistant temperature of 150 ° C or higher. Therefore, those having an amide group (amide bond) in the molecule are preferred, and those containing a structural unit derived from a monomer represented by the following general formula (1) are more preferred. When a polymer is formed using a monomer represented by the following general formula (1), a carbon-carbon double bond portion is cleaved to form a main chain. Therefore, the organic binder containing a structural unit derived from a monomer represented by the following general formula (1) has a side chain containing a moiety [—NR 3 — (C═O) —R 2 ] containing an amide group. Become.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
　前記一般式（１）中、Ｒ１は水素またはメチル基、Ｒ２およびＲ３は、Ｒ２が水素もしくは炭素数１～６のアルキル基およびＲ３が水素もしくは炭素数１～４のアルキル基であるか、またはＲ２とＲ３とが互いに結合して環を形成しており、前記環のＲ２およびＲ３における炭素数の合計が２～１０である。 In the general formula (1), R 1 is hydrogen or a methyl group, R 2 and R 3 are R 2 is hydrogen or an alkyl group having 1 to 6 carbon atoms, and R 3 is hydrogen or an alkyl group having 1 to 4 carbon atoms. Or R 2 and R 3 are bonded to each other to form a ring, and the total number of carbon atoms in R 2 and R 3 of the ring is 2 to 10.
　なお、Ｒ２における炭素数１～６のアルキル基には、直鎖アルキル基、分岐状アルキル基、環状アルキル基など、炭素数１～６のアルキル基全般が含まれる。また、Ｒ３における炭素数１～４のアルキル基には、直鎖アルキル基、分岐状アルキル基、環状アルキル基など、炭素数１～４のアルキル基全般が含まれる。 Note that the alkyl group having 1 to 6 carbon atoms in R 2 includes all alkyl groups having 1 to 6 carbon atoms such as a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. In addition, the alkyl group having 1 to 4 carbon atoms in R 3 includes all alkyl groups having 1 to 4 carbon atoms such as a linear alkyl group, a branched alkyl group, and a cyclic alkyl group.
　前記一般式（１）で表されるモノマー由来の構造単位を含む有機バインダとしては、例えば、前記一般式（１）で表されるモノマーの単独重合体や共重合体が挙げられる。 Examples of the organic binder containing a structural unit derived from the monomer represented by the general formula (1) include a homopolymer and a copolymer of the monomer represented by the general formula (1).
　前記一般式（１）で表されるモノマーとしては、例えば、Ｎ－ビニルアセトアミド、Ｎ－ビニルホルムアミド、Ｎ－メチル，Ｎ－ビニルホルムアミド、Ｎ－ビニルピロリドン、Ｎ－ビニル－２－カプロラクタムなどが挙げられる。 Examples of the monomer represented by the general formula (1) include N-vinylacetamide, N-vinylformamide, N-methyl, N-vinylformamide, N-vinylpyrrolidone, N-vinyl-2-caprolactam and the like. It is done.
　よって、前記一般式（１）で表されるモノマーの単独重合体としては、例えば、ポリＮ－ビニルアセトアミド、ポリＮ－ビニルホルムアミド、ポリＮ－メチル，Ｎ－ビニルホルムアミド、ポリＮ－ビニルピロリドン、ポリＮ－ビニル－２－カプロラクタムなどが挙げられる。 Therefore, as a homopolymer of the monomer represented by the general formula (1), for example, poly N-vinylacetamide, poly N-vinylformamide, poly N-methyl, N-vinylformamide, poly N-vinylpyrrolidone, Examples thereof include poly N-vinyl-2-caprolactam.
　前記一般式（１）で表されるモノマーの共重合体としては、例えば、Ｎ－ビニルアセトアミドと、Ｎ－ビニルアセトアミド以外のエチレン性不飽和モノマーとの共重合体；Ｎ－ビニルホルムアミドと、Ｎ－ビニルホルムアミド以外のエチレン性不飽和モノマーとの共重合体；Ｎ－メチル，Ｎ－ビニルホルムアミドと、Ｎ－メチル，Ｎ－ビニルホルムアミド以外のエチレン性不飽和モノマーとの共重合体；Ｎ－ビニルピロリドンと、Ｎ－ビニルピロリドン以外のエチレン性不飽和モノマーとの共重合体；などが挙げられる。また、前記一般式（１）で表されるモノマーの共重合体には、前記一般式（１）で表されるモノマーを２種以上用いた共重合体も含まれる。 Examples of the copolymer of the monomer represented by the general formula (1) include a copolymer of N-vinylacetamide and an ethylenically unsaturated monomer other than N-vinylacetamide; N-vinylformamide, N -Copolymer of ethylenically unsaturated monomers other than vinylformamide; Copolymer of N-methyl, N-vinylformamide and ethylenically unsaturated monomers other than N-methyl, N-vinylformamide; N-vinyl And a copolymer of pyrrolidone and an ethylenically unsaturated monomer other than N-vinylpyrrolidone. Moreover, the copolymer using the monomer represented by the said General formula (1) is also contained in the copolymer of the monomer represented by the said General formula (1).
　前記の共重合体の形成に用い得るエチレン性不飽和モノマー［前記一般式（１）で表されるモノマー以外のエチレン性不飽和モノマー］としては、例えば、アクリル酸、メタクリル酸、メチルアクリレート、エチルアクリレート、プロピルアクリレート、ブチルアクリレート、オクチルアクリレート、メチルメタクリレート、エチルメタクリレート、プロピルメタクリレート、ブチルメタクリレート、オクチルメタクリレート、２－ヒドロキシエチルアクリレート、２－ヒドロキシエチルメタクリレート、２－ヒドロキシプロピルメタクリレート、アクリロニトリル、メタクリロニトリル、酢酸ビニル、アクリルアミド、メタクリルアミド、Ｎ－メチルアクリルアミド、Ｎ，Ｎ－ジメチルアクリルアミド、Ｎ－イソプロピルアクリルアミド、ビニルピロリドン、マレイン酸、イタコン酸、２－アクリルアミド－２－メチル－プロパンスルホン酸、２－アクリルアミドエタンスルホン酸、２－メタクリルアミドエタンスルホン酸、３－メタクリルアミドプロパンスルホン酸、アクリル酸メチルスルホン酸、メタクリル酸メチルスルホン酸、アクリル酸－２－エチルスルホン酸、メタクリル酸－２－エチルスルホン酸、アクリル酸－３－プロピルスルホン酸、メタクリル酸－３－プロピルスルホン酸、アクリル酸－２－メチル－３－プロピルスルホン酸、メタクリル酸－２－メチル－３－プロピルスルホン酸、アクリル酸－１，１’－ジメチル－２－エチルスルホン酸、メタクリル酸－１，１’－ジメチル－２－エチルスルホン酸またはそれらの塩、メチルビニルケトン、エチルビニルケトン、メチルビニルエーテル、エチルビニルエーテル、含フッ素エチレン、スチレンまたはその誘導体、ビニルアリルベンゼンなどが挙げられ、これらのうちの１種のみを使用してもよく、２種以上を併用してもよい。 Examples of the ethylenically unsaturated monomer [ethylenically unsaturated monomer other than the monomer represented by the general formula (1)] that can be used for forming the copolymer include acrylic acid, methacrylic acid, methyl acrylate, and ethyl. Acrylate, propyl acrylate, butyl acrylate, octyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, acrylonitrile, methacrylonitrile, Vinyl acetate, acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-isopropylacrylamide Vinylpyrrolidone, maleic acid, itaconic acid, 2-acrylamido-2-methyl-propanesulfonic acid, 2-acrylamide ethanesulfonic acid, 2-methacrylamide ethanesulfonic acid, 3-methacrylamide propanesulfonic acid, methyl acrylate sulfonic acid, Methyl methacrylate sulfonic acid, acrylic acid-2-ethylsulfonic acid, methacrylic acid-2-ethylsulfonic acid, acrylic acid-3-propylsulfonic acid, methacrylic acid-3-propylsulfonic acid, acrylic acid-2-methyl-3 -Propylsulfonic acid, methacrylic acid-2-methyl-3-propylsulfonic acid, acrylic acid-1,1'-dimethyl-2-ethylsulfonic acid, methacrylic acid-1,1'-dimethyl-2-ethylsulfonic acid or Their salts, methyl vinyl ketone, ethyl vinyl Ketones, methyl vinyl ether, ethyl vinyl ether, fluorine-containing ethylene, styrene or a derivative thereof, such as vinyl allyl benzene, and the like, may be used only one of these may be used in combination of two or more.
　前記一般式（１）で表されるモノマーと、前記一般式（１）で表されるモノマー以外のエチレン性不飽和モノマーとの共重合体における共重合比（質量比）は、後者のエチレン性不飽和モノマーが２～５０質量％であることが好ましい。 The copolymerization ratio (mass ratio) in the copolymer of the monomer represented by the general formula (1) and the ethylenically unsaturated monomer other than the monomer represented by the general formula (1) is the latter ethylenic property. The unsaturated monomer is preferably 2 to 50% by mass.
　分子内にアミド基を有する有機バインダ［好ましくは、前記一般式（１）で表されるモノマー由来の構造単位を含む有機バインダ］の分子量は、ゲルパーミエーションクロマトグラフィーを用いて測定される数平均分子量（ポリスチレン換算値）で、１０００以上であることが好ましく、４０００以上であることがより好ましく、また、１００００００以下であることが好ましく、７０００００以下であることがより好ましく、５０００００以下であることが更に好ましい。 The molecular weight of an organic binder having an amide group in the molecule [preferably, an organic binder containing a structural unit derived from the monomer represented by the general formula (1)] is a number average measured using gel permeation chromatography. The molecular weight (in terms of polystyrene) is preferably 1000 or more, more preferably 4000 or more, and preferably 1000000 or less, more preferably 700000 or less, and 500000 or less. Further preferred.
　耐熱性多孔質膜は、例えば、エチレン－酢酸ビニル共重合体（ＥＶＡ、酢酸ビニル由来の構造単位が２０～３５モル％のもの）、（メタ）アクリレート重合体［「（メタ）アクリレート」とは、アクリレートとメタクリレートとを含む意味である。以下、同じ。］、フッ素系ゴム、スチレンブタジエンゴム（ＳＢＲ）、ポリビニルアルコール（ＰＶＡ）、ポリビニルブチラール（ＰＶＢ）、ポリウレタンなどの樹脂のうちの１種または２種以上を有機バインダとして用いてもよく、これらの樹脂の１種または２種以上と前記の分子内にアミド基を有する有機バインダとを併用してもよい。 Examples of heat-resistant porous membranes include ethylene-vinyl acetate copolymer (EVA, having a structural unit derived from vinyl acetate of 20 to 35 mol%), (meth) acrylate polymer [What is “(meth) acrylate”? , And acrylate and methacrylate. same as below. ], Fluorine type rubber, styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), one or more types of resins such as polyurethane may be used as the organic binder. One or more of the above and an organic binder having an amide group in the molecule may be used in combination.
　耐熱性多孔質膜に係る耐熱温度が１５０℃以上の微粒子は、耐熱性多孔質膜の主体となったり、後述する繊維状物同士の間に形成される空隙を埋めるなどして、リチウムデンドライトに起因する短絡の発生を抑制する作用を有している。なお、本明細書でいう、耐熱温度が１５０℃以上の微粒子、および耐熱温度が１５０℃以上の繊維状物（後述する）における「耐熱温度が１５０℃以上」とは、少なくとも１５０℃において変形などの形状変化が目視で確認されないことを意味している。 The fine particles having a heat resistant temperature of 150 ° C. or more related to the heat resistant porous film are used as a main component of the heat resistant porous film or fill a void formed between fibrous materials to be described later. It has the effect of suppressing the occurrence of the short circuit. In the present specification, the term “heat-resistant temperature is 150 ° C. or higher” in fine particles having a heat-resistant temperature of 150 ° C. or higher and fibrous materials having a heat-resistant temperature of 150 ° C. or higher (described later) refers to deformation at least at 150 ° C. This means that no shape change is visually confirmed.
　耐熱温度が１５０℃以上の微粒子としては、電気絶縁性を有しており、電気化学的に安定で、更に電池の有する非水電解質（非水電解液）や、耐熱性多孔質膜形成用組成物（溶媒を含む組成物）に用いる溶媒に対して安定であれば特に制限はない。なお、本明細書でいう「非水電解質に対して安定」とは、非水電池に係る非水電解質中で変形および化学的組成変化を起こさないことを意味している。また、本明細書でいう「電気化学的に安定」とは、電池の充放電の際に化学変化が生じないことを意味している。 The fine particles having a heat-resistant temperature of 150 ° C. or higher have electrical insulation properties, are electrochemically stable, and further have a non-aqueous electrolyte (non-aqueous electrolyte solution) or a composition for forming a heat-resistant porous film. If it is stable with respect to the solvent used for a thing (composition containing a solvent), there will be no restriction | limiting in particular. As used herein, “stable with respect to the non-aqueous electrolyte” means that no deformation or chemical composition change occurs in the non-aqueous electrolyte of the non-aqueous battery. In addition, the term “electrochemically stable” as used in the present specification means that no chemical change occurs during charging / discharging of the battery.
　このような耐熱温度が１５０℃以上の微粒子の具体例としては、例えば、酸化鉄、ＳｉＯ２、Ａｌ２Ｏ３、ＴｉＯ２、ＢａＴｉＯ３、ＺｒＯ２などの酸化物微粒子；窒化アルミニウム、窒化ケイ素などの窒化物微粒子；フッ化カルシウム、フッ化バリウム、硫酸バリウムなどの難溶性のイオン結晶微粒子；シリコン、ダイヤモンドなどの共有結合性結晶微粒子；タルク、モンモリロナイトなどの粘土微粒子；ベーマイト、ゼオライト、アパタイト、カオリン、ムライト、スピネル、オリビン、セリサイト、ベントナイト、ハイドロタルサイトなどの鉱物資源由来物質あるいはそれらの人造物；などの無機微粒子が挙げられる。また、金属微粒子；ＳｎＯ２、スズ－インジウム酸化物（ＩＴＯ）などの酸化物微粒子；カーボンブラック、グラファイトなどの炭素質微粒子；などの導電性微粒子の表面を、電気絶縁性を有する材料（例えば、前記の電気絶縁性の絶縁性微粒子を構成する材料など）で表面処理することで、電気絶縁性を持たせた微粒子であってもよい。 Specific examples of such fine particles having a heat-resistant temperature of 150 ° C. or more include, for example, oxide fine particles such as iron oxide, SiO 2 , Al 2 O 3 , TiO 2 , BaTiO 3 , ZrO 2 ; aluminum nitride, silicon nitride, etc. Nitride fine particles: Calcium fluoride, barium fluoride, barium sulfate and other poorly soluble ionic crystal fine particles; silicon, diamond and other covalently bonded crystal fine particles; talc, montmorillonite and other clay fine particles; boehmite, zeolite, apatite, kaolin Inorganic fine particles such as mullite, spinel, olivine, sericite, bentonite, hydrotalcite, and other mineral resource-derived substances or artificial products thereof. Further, the surface of conductive fine particles such as metal fine particles; oxide fine particles such as SnO 2 and tin-indium oxide (ITO); carbonaceous fine particles such as carbon black and graphite; It may be fine particles that have been made electrically insulating by surface treatment with the above-mentioned materials constituting the electrically insulating fine particles.
　また、耐熱温度が１５０℃以上の微粒子には、有機微粒子を用いることもできる。有機微粒子の具体例としては、ポリイミド、メラミン系樹脂、フェノール系樹脂、架橋ポリメチルメタクリレート（架橋ＰＭＭＡ）、架橋ポリスチレン（架橋ＰＳ）、ポリジビニルベンゼン（ＰＤＶＢ）、ベンゾグアナミン－ホルムアルデヒド縮合物などの架橋高分子の微粒子；熱可塑性ポリイミドなどの耐熱性高分子の微粒子；が挙げられる。これらの有機微粒子を構成する有機樹脂（高分子）は、前記例示の材料の混合物、変性体、誘導体、共重合体（ランダム共重合体、交互共重合体、ブロック共重合体、グラフト共重合体）、架橋体（前記の耐熱性高分子の場合）であってもよい。 Also, organic fine particles can be used for the fine particles having a heat resistant temperature of 150 ° C. or higher. Specific examples of organic fine particles include polyimide, melamine resin, phenol resin, crosslinked polymethylmethacrylate (crosslinked PMMA), crosslinked polystyrene (crosslinked PS), polydivinylbenzene (PDVB), benzoguanamine-formaldehyde condensate, etc. Molecular fine particles; heat-resistant polymer fine particles such as thermoplastic polyimide; The organic resin (polymer) constituting these organic fine particles is a mixture, modified body, derivative, copolymer (random copolymer, alternating copolymer, block copolymer, graft copolymer) of the materials exemplified above. ) Or a crosslinked product (in the case of the heat-resistant polymer).
　耐熱温度が１５０℃以上の微粒子には、前記例示の各種微粒子を１種単独で使用してもよく、２種以上を併用してもよい。また、耐熱温度が１５０℃以上の微粒子は、前記例示の各種微粒子を構成する材料を２種以上含有する粒子であってもよい。なお、前記例示の各種微粒子の中でも、例えば、耐熱性多孔質膜の耐酸化性をより高め得ることから、無機酸化物微粒子が好ましく、アルミナ、シリカ、ベーマイトがより好ましい。 As the fine particles having a heat-resistant temperature of 150 ° C. or higher, the various fine particles exemplified above may be used alone or in combination of two or more. The fine particles having a heat resistant temperature of 150 ° C. or higher may be particles containing two or more kinds of materials constituting the various fine particles exemplified above. Among the various exemplified fine particles, inorganic oxide fine particles are preferable, and alumina, silica, and boehmite are more preferable because, for example, the oxidation resistance of the heat-resistant porous film can be further improved.
　耐熱温度が１５０℃以上の微粒子の形態としては、球状、粒子状、板状などいずれの形態であってもよいが、板状であることが好ましい。板状粒子としては、各種市販品が挙げられ、例えば、旭硝子エスアイテック社製「サンラブリー」（ＳｉＯ２）、石原産業社製「ＮＳＴ－Ｂ１」の粉砕品（ＴｉＯ２）、堺化学工業社製の板状硫酸バリウム「Ｈシリーズ」、「ＨＬシリーズ」、林化成社製「ミクロンホワイト」（タルク）、林化成社製「ベンゲル」（ベントナイト）、河合石灰社製「ＢＭＭ」や「ＢＭＴ」（ベーマイト）、河合石灰社製「セラシュールＢＭＴ－Ｂ」［アルミナ（Ａｌ２Ｏ３）］、キンセイマテック社製「セラフ」（アルミナ）、斐川鉱業社製「斐川マイカ　Ｚ－２０」（セリサイト）などが入手可能である。この他、ＳｉＯ２、Ａｌ２Ｏ３、ＺｒＯ２およびＣｅＯ２については、特開２００３－２０６４７５号公報に開示の方法により作製することができる。 The form of the fine particles having a heat resistant temperature of 150 ° C. or higher may be any form such as a spherical shape, a particle shape, or a plate shape, but a plate shape is preferable. Examples of the plate-like particles include various commercially available products. For example, “Sun Lovely” (SiO 2 ) manufactured by Asahi Glass Stech Co., Ltd., “NST-B1” pulverized product (TiO 2 ) manufactured by Ishihara Sangyo Co., Ltd., Sakai Chemical Industry Co., Ltd. Plate-like barium sulfate “H series”, “HL series”, Hayashi Kasei “micron white” (talc), Hayashi Kasei “bengel” (bentonite), Kawai lime “BMM” and “BMT” (Boehmite), “Cerasure BMT-B” [Alumina (Al 2 O 3 )] manufactured by Kawai Lime Co., Ltd., “Seraph” (alumina) manufactured by Kinsei Matech Co., Ltd., “Yodogawa Mica Z-20” manufactured by Yodogawa Mining Co., Ltd. (Sericite) ) Etc. are available. In addition, SiO 2 , Al 2 O 3 , ZrO 2 and CeO 2 can be produced by the method disclosed in Japanese Patent Laid-Open No. 2003-206475.
　耐熱温度が１５０℃以上の微粒子が板状である場合には、耐熱性多孔質膜中において、前記微粒子を、その平板面が耐熱性多孔質膜の面にほぼ平行となるように配向させることが好ましく、このような耐熱性多孔質膜を使用することで、電池の短絡の発生をより良好に抑制できる。これは、耐熱温度が１５０℃以上の微粒子を前記のように配向させることで、微粒子同士が平板面の一部で重なるように配置されるため、耐熱性多孔質膜の片面から他面に向かう空孔（貫通孔）が、直線ではなく曲折した形で形成される（すなわち、曲路率が大きくなる）と考えられ、これにより、リチウムデンドライトが耐熱性多孔質膜を貫通することを防止できることから、短絡の発生がより良好に抑制されるものと推測される。 When the fine particles having a heat-resistant temperature of 150 ° C. or higher are plate-like, the fine particles are oriented in the heat-resistant porous film so that the flat plate surface is substantially parallel to the surface of the heat-resistant porous film. The use of such a heat-resistant porous membrane can better suppress the occurrence of short circuits in the battery. This is because the fine particles having a heat-resistant temperature of 150 ° C. or more are oriented as described above, and the fine particles are arranged so as to overlap each other on a part of the flat plate surface, so that the heat-resistant porous film is directed from one side to the other side. It is considered that vacancies (through holes) are formed not in a straight line but in a bent shape (that is, the curvature is increased), thereby preventing lithium dendrite from penetrating through the heat-resistant porous film. Therefore, it is presumed that the occurrence of a short circuit is suppressed better.
　耐熱温度が１５０℃以上の微粒子が板状の粒子である場合の形態としては、例えば、アスペクト比（板状粒子中の最大長さ／板状粒子の厚み）が、５以上であることが好ましく、１０以上であることがより好ましく、また、１００以下であることが好ましく、５０以下であることがより好ましい。また、粒子の平板面の長軸方向長さと短軸方向長さの比（短軸方向長さ／長軸方向長さ）の平均値は、０．３以上であることが好ましく、０．５以上であることがより好ましい（１、すなわち、長軸方向長さと短軸方向長さとが同じであってもよい）。耐熱温度が１５０℃以上の微粒子が、前記のようなアスペクト比や平板面の長軸方向長さと短軸方向長さの比の平均値を有する板状粒子である場合には、前記の短絡防止作用がより有効に発揮される。 For example, the aspect ratio (maximum length in the plate-like particles / thickness of the plate-like particles) is preferably 5 or more as the form when the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like particles. 10 or more is more preferable, 100 or less is preferable, and 50 or less is more preferable. Further, the average value of the ratio of the length in the major axis direction to the length in the minor axis direction (length in the minor axis direction / length in the major axis direction) of the tabular surface of the grain is preferably 0.3 or more, 0.5 It is more preferable that the number is 1 (that is, the length in the major axis direction and the length in the minor axis direction may be the same). When the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like particles having the aspect ratio and the average value of the ratio of the long axis direction length to the short axis direction of the flat plate surface, the above-mentioned short circuit prevention The effect is exhibited more effectively.
　耐熱温度が１５０℃以上の微粒子が板状である場合における前記の平板面の長軸方向長さと短軸方向長さの比の平均値は、例えば、走査型電子顕微鏡（ＳＥＭ）により撮影した画像を画像解析することにより求めることができる。更に耐熱温度が１５０℃以上の微粒子が板状である場合における前記のアスペクト比も、ＳＥＭにより撮影した画像を、画像解析することにより求めることができる。 The average value of the ratio of the length in the major axis direction to the length in the minor axis direction of the flat plate surface when the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like, for example, an image taken with a scanning electron microscope (SEM) Can be obtained by image analysis. Further, the aspect ratio in the case where the fine particles having a heat resistant temperature of 150 ° C. or higher are plate-like can also be obtained by image analysis of an image taken by SEM.
　耐熱温度が１５０℃以上の微粒子の平均粒子径は、小さすぎると、前記の有機バインダ量では、微粒子同士の結着を十分に得られない虞があることから、０．０１μｍ以上であり、０．１μｍ以上であることが好ましい。ただし、耐熱温度が１５０℃以上の微粒子の平均粒子径が大きすぎると、耐熱性多孔質膜が厚くなりすぎて、これを用いた電池のエネルギー密度が低下するなどの虞がある。よって、耐熱温度が１５０℃以上の微粒子の平均粒子径は、１０μｍ以下であり、５μｍ以下であることが好ましい。なお、本明細書でいう耐熱温度が１５０℃以上の微粒子の平均粒子径は、例えば、レーザー散乱粒度分布計（例えば、ＨＯＲＩＢＡ社製「ＬＡ－９２０」）を用い、耐熱温度が１５０℃以上の微粒子を溶解したり、耐熱温度が１５０℃以上の微粒子が膨潤したりしない媒体に、耐熱温度が１５０℃以上の微粒子を分散させて測定した数平均粒子径として規定することができる。 If the average particle size of the fine particles having a heat resistant temperature of 150 ° C. or higher is too small, the amount of the organic binder may not be sufficient to bind the fine particles. It is preferably 1 μm or more. However, if the average particle size of the fine particles having a heat resistant temperature of 150 ° C. or higher is too large, the heat resistant porous membrane becomes too thick, and there is a risk that the energy density of a battery using this will decrease. Therefore, the average particle diameter of the fine particles having a heat resistant temperature of 150 ° C. or higher is 10 μm or less, and preferably 5 μm or less. As used herein, the average particle size of the fine particles having a heat resistance temperature of 150 ° C. or higher is, for example, a laser scattering particle size distribution meter (for example, “LA-920” manufactured by HORIBA) and having a heat resistance temperature of 150 ° C. or higher. It can be defined as a number average particle diameter measured by dispersing fine particles having a heat resistant temperature of 150 ° C. or higher in a medium in which the fine particles are not dissolved or fine particles having a heat resistant temperature of 150 ° C. or higher are not swollen.
　また、耐熱温度が１５０℃以上の微粒子の比表面積は、１００ｍ２／ｇ以下であることが好ましく、５０ｍ２／ｇ以下であることがより好ましく、３０ｍ２／ｇ以下であることが更に好ましい。耐熱温度が１５０℃以上の微粒子の比表面積が大きくなると、一般に、微粒子同士や、微粒子と基材や電極とを良好に結着するために必要となる有機バインダの量が多くなる傾向にあり、耐熱性多孔質膜における有機バインダの割合を、前記の値に調整し難くなる虞がある。また、耐熱温度が１５０℃以上の微粒子の比表面積が大きくなると、微粒子表面に吸着する水分が大きくなって、非水電池の電池特性を低下させる虞もある。一方、耐熱温度が１５０℃以上の微粒子の比表面積は、１ｍ２／ｇ以上であることが好ましい。本明細書で耐熱温度が１５０℃以上の微粒子の比表面積は、窒素ガスを用いてＢＥＴ法により測定した値である。 The specific surface area of the fine particles having a heat resistant temperature of 150 ° C. or higher is preferably 100 m 2 / g or less, more preferably 50 m 2 / g or less, and further preferably 30 m 2 / g or less. When the specific surface area of the fine particles having a heat-resistant temperature of 150 ° C. or higher is increased, generally, the amount of the organic binder required to bind the fine particles to each other well, and the fine particles to the base material and the electrode tends to increase. There is a possibility that it is difficult to adjust the ratio of the organic binder in the heat-resistant porous film to the above value. In addition, when the specific surface area of the fine particles having a heat resistant temperature of 150 ° C. or higher is increased, the moisture adsorbed on the surface of the fine particles is increased, which may deteriorate the battery characteristics of the nonaqueous battery. On the other hand, the specific surface area of the fine particles having a heat resistant temperature of 150 ° C. or higher is preferably 1 m 2 / g or higher. In this specification, the specific surface area of fine particles having a heat resistant temperature of 150 ° C. or higher is a value measured by a BET method using nitrogen gas.
　また、本発明の耐熱性多孔質膜は、耐熱温度が１５０℃以上といった耐熱性の高い微粒子を用いているため、その作用によって、高温時における熱収縮が抑制されており高い寸法安定性を有している。更に、このような耐熱性の高い耐熱性多孔質膜が電極（正極および／または負極）と一体化している場合には、高温時における耐熱性多孔質膜全体の寸法安定性が更に向上する。一方、多孔質基材と本発明の耐熱性多孔質膜とが一体化されて構成された本発明の非水電池用セパレータは、多孔質基材が例えばポリオレフィン製微多孔膜のように高温時の寸法安定性に劣るものであっても、耐熱温度が１５０℃以上の微粒子の作用によって高温時の寸法安定性が良好な耐熱性多孔質膜と一体化していることから、多孔質基材の熱収縮が抑制され、高温時におけるセパレータ全体の寸法安定性が向上する。そのため、電極と一体化した本発明の耐熱性多孔質膜を有する非水電池や、本発明の非水電池用セパレータを有する非水電池では、例えば従来のポリエチレン製微多孔膜のみで構成されるセパレータを用いた電池で生じていたセパレータの熱収縮に起因する短絡の発生が防止できることから、電池内が異常過熱した際の信頼性および安全性をより高めることができる。 In addition, since the heat-resistant porous film of the present invention uses fine particles having high heat resistance such as a heat-resistant temperature of 150 ° C. or higher, the action prevents thermal shrinkage at high temperatures and has high dimensional stability. is doing. Furthermore, when such a heat-resistant porous film having high heat resistance is integrated with the electrode (positive electrode and / or negative electrode), the overall dimensional stability of the heat-resistant porous film at high temperatures is further improved. On the other hand, the separator for a non-aqueous battery of the present invention in which the porous substrate and the heat-resistant porous membrane of the present invention are integrated is a porous substrate whose temperature is high, such as a polyolefin microporous membrane. Even if it is inferior in dimensional stability, it is integrated with a heat-resistant porous film having good dimensional stability at high temperatures by the action of fine particles having a heat-resistant temperature of 150 ° C. or higher. Thermal shrinkage is suppressed, and the dimensional stability of the entire separator at high temperatures is improved. Therefore, the non-aqueous battery having the heat-resistant porous membrane of the present invention integrated with the electrode and the non-aqueous battery having the non-aqueous battery separator of the present invention are composed of, for example, only a conventional polyethylene microporous membrane. Since the occurrence of a short circuit due to the thermal contraction of the separator that has occurred in the battery using the separator can be prevented, the reliability and safety when the inside of the battery is abnormally overheated can be further increased.
　また、本発明の耐熱性多孔質膜を有する非水電池（本発明の非水電池）では、高温時におけるセパレータの熱収縮に起因する短絡の防止を、例えばセパレータを厚くする以外の構成で達成できるため、正極と負極とを仕切る隔離材（本発明の耐熱性多孔質膜または本発明の非水電池用セパレータ）の厚みを比較的薄くすることが可能であり、これにより、エネルギー密度の低下を可及的に抑制することもできる。 Further, in the nonaqueous battery having the heat resistant porous membrane of the present invention (nonaqueous battery of the present invention), prevention of a short circuit due to the thermal contraction of the separator at a high temperature is achieved with a configuration other than increasing the thickness of the separator, for example. Therefore, it is possible to make the thickness of the separator (the heat-resistant porous membrane of the present invention or the separator for a non-aqueous battery of the present invention) that separates the positive electrode and the negative electrode relatively thin, thereby reducing the energy density. Can be suppressed as much as possible.
　耐熱性多孔質膜中における耐熱温度が１５０℃以上の微粒子の量は、前記微粒子を使用することによる作用をより有効に発揮させる観点から、耐熱性多孔質膜の全固形分の全体積中、１０体積％以上であることが好ましく、３０体積％以上であることがより好ましく、４０体積％以上であることが更に好ましい。 The amount of fine particles having a heat resistant temperature of 150 ° C. or higher in the heat resistant porous membrane is from the viewpoint of more effectively exerting the effect of using the fine particles, in the total volume of the total solid content of the heat resistant porous membrane, It is preferably 10% by volume or more, more preferably 30% by volume or more, and still more preferably 40% by volume or more.
　後記の繊維状物を含有しない耐熱性多孔質膜であって、後記の熱溶融性微粒子や膨潤性微粒子を含有させてシャットダウン機能も持たせる場合には、耐熱温度が１５０℃以上の微粒子の耐熱性多孔質膜中の量は、例えば、耐熱性多孔質膜の全固形分の全体積中、８０体積％以下であることが好ましい。また、後記の繊維状物を含有せず、かつシャットダウン機能を有しない耐熱性多孔質膜とする場合には、耐熱温度が１５０℃以上の微粒子の耐熱性多孔質膜中の量は更に多くてもよく、具体的には、耐熱性多孔質膜の全固形分の全体積中、９９.５体積％以下であれば問題ない。 When the heat-resistant porous film does not contain a fibrous material, which will be described later, and contains a heat-meltable fine particle or a swellable fine particle, which will be described later, and has a shutdown function, the heat resistance of the fine particles having a heat-resistant temperature of 150 ° C. or higher. The amount in the porous porous membrane is preferably 80% by volume or less in the total volume of the total solid content of the heat resistant porous membrane, for example. In addition, when the heat-resistant porous film does not contain a fibrous material described later and does not have a shutdown function, the amount of fine particles having a heat-resistant temperature of 150 ° C. or higher in the heat-resistant porous film is much larger. Specifically, there is no problem if it is 99.5% by volume or less in the total volume of the total solid content of the heat-resistant porous membrane.
　他方、後記の繊維状物を含有する耐熱性多孔質膜であって、後記の熱溶融性微粒子や膨潤性微粒子を含有させてシャットダウン機能も持たせる場合には、耐熱温度が１５０℃以上の微粒子の耐熱性多孔質膜中の量は、例えば、耐熱性多孔質膜の全固形分の全体積中、７０体積％以下であることが好ましい。また、後記の繊維状物を含有し、かつシャットダウン機能を有しない耐熱性多孔質膜とする場合には、耐熱温度が１５０℃以上の微粒子の耐熱性多孔質膜中の量は更に多くてもよく、具体的には、耐熱性多孔質膜の全固形分の全体積中、８０体積％以下であれば問題ない。 On the other hand, in the case of a heat-resistant porous film containing a fibrous material to be described later, and containing a heat-meltable fine particle and a swellable fine particle to have a shutdown function, fine particles having a heat-resistant temperature of 150 ° C. or higher The amount in the heat resistant porous membrane is preferably 70% by volume or less in the total volume of the total solid content of the heat resistant porous membrane, for example. In addition, when a heat-resistant porous film containing a fibrous material described later and having no shutdown function is used, the amount of fine particles having a heat-resistant temperature of 150 ° C. or higher in the heat-resistant porous film may be larger. Specifically, there is no problem as long as it is 80% by volume or less in the total volume of the total solid content of the heat-resistant porous membrane.
　耐熱性多孔質膜は、繊維状物を含有していてもよい。繊維状物を含有することで、耐熱性多孔質膜の強度を高めることができる。なお、本明細書でいう「繊維状物」とは、アスペクト比［長尺方向の長さ／長尺方向に直交する方向の幅（直径）］が４以上のものを意味している。繊維状物のアスペクト比は、１０以上であることが好ましい。 The heat resistant porous membrane may contain a fibrous material. By containing a fibrous material, the strength of the heat-resistant porous film can be increased. The “fibrous material” in the present specification means that having an aspect ratio [length in the longitudinal direction / width (diameter) in a direction perpendicular to the longitudinal direction] of 4 or more. The aspect ratio of the fibrous material is preferably 10 or more.
　繊維状物は、耐熱温度が１５０℃以上であることが好ましい。例えば、１４０℃以下の温度で溶融して耐熱性多孔質膜の空孔を塞ぎ、耐熱性多孔質膜中のイオンの移動を遮断する機能（いわゆるシャットダウン機能）を付与できる材料を耐熱性多孔質膜に含有させた場合（詳しくは後述する）、耐熱温度が１５０℃以上の繊維状物も多孔質膜に含有させておくことで、電池内での発熱などによってシャットダウンが起こった後、更に１０℃以上セパレータの温度が上昇しても、その形状をより安定に保ち得るようにできる。他方、シャットダウン機能を付与していない場合でも、耐熱温度が１５０℃以上の繊維状物も用いた耐熱性多孔質膜や、更にこの耐熱性多孔質膜を用いたセパレータでは、１５０℃の温度においても、その変形を実質的になくすことができる。 The fibrous material preferably has a heat resistant temperature of 150 ° C. or higher. For example, a material that can be melted at a temperature of 140 ° C. or less to block the pores of the heat-resistant porous film and provide a function of blocking the movement of ions in the heat-resistant porous film (so-called shutdown function) When it is contained in the membrane (details will be described later), a fibrous material having a heat-resistant temperature of 150 ° C. or higher is also contained in the porous membrane, so that a shutdown occurs due to heat generation in the battery, and then 10 Even if the temperature of the separator rises by more than 0 ° C., the shape can be kept more stable. On the other hand, even when the shutdown function is not given, the heat resistant porous film using a fibrous material having a heat resistant temperature of 150 ° C. or higher, and further the separator using this heat resistant porous film, at a temperature of 150 ° C. However, the deformation can be substantially eliminated.
　繊維状物は、好ましくは耐熱温度が１５０℃以上であり、かつ電気絶縁性を有しており、電気化学的に安定で、更に非水電池の有する非水電解質（非水電解液）や、耐熱性多孔質膜形成用組成物に用いる溶媒に安定であれば、更に好ましい。 The fibrous material preferably has a heat-resistant temperature of 150 ° C. or higher, and has an electrical insulating property, is electrochemically stable, and further has a non-aqueous electrolyte (non-aqueous electrolyte) included in a non-aqueous battery, It is more preferable if the solvent used in the heat-resistant porous film-forming composition is stable.
　繊維状物の具体的な構成材料としては、例えば、セルロース、セルロース変成体（カルボキシメチルセルロースなど）、ポリプロピレン（ＰＰ）、ポリエステル［ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）、ポリブチレンテレフタレート（ＰＢＴ）など］、ポリアクリロニトリル（ＰＡＮ）、アラミド、ポリアミドイミド、ポリイミドなどの樹脂；ガラス、アルミナ、シリカなどの無機材料（無機酸化物）；などが挙げられる。繊維状物は、これらの構成材料の１種を含有していてもよく、２種以上を含有していても構わない。また、繊維状物は、構成成分として、前記の構成材料の他に、必要に応じて、公知の各種添加剤（例えば、樹脂である場合には酸化防止剤など）を含有していても構わない。 Specific constituent materials of the fibrous material include, for example, cellulose, modified cellulose (such as carboxymethyl cellulose), polypropylene (PP), polyester [polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT). And the like], resins such as polyacrylonitrile (PAN), aramid, polyamideimide, and polyimide; inorganic materials (inorganic oxides) such as glass, alumina, and silica; and the like. The fibrous material may contain one kind of these constituent materials, or may contain two or more kinds. In addition to the above-described constituent materials, the fibrous material may contain various known additives (for example, an antioxidant in the case of a resin) as necessary. Absent.
　繊維状物には、耐熱温度が１５０℃以上の微粒子との接着性を高めるために、コロナ処理や界面活性剤処理などの表面処理を施してもよい。 The fibrous material may be subjected to a surface treatment such as a corona treatment or a surfactant treatment in order to enhance adhesion with fine particles having a heat resistant temperature of 150 ° C. or higher.
　繊維状物の直径は、耐熱性多孔質膜の厚み以下であればよいが、例えば、０．０１～５μｍであることが好ましい。径が大きすぎると、繊維状物同士の絡み合いが不足して、例えば、繊維状物を使用することによる耐熱性多孔質膜の強度向上効果が小さくなる虞がある。また、径が小さすぎると、耐熱性多孔質膜の空孔が小さくなりすぎて、イオン透過性が低下する傾向にあり、電池の出力特性向上効果が小さくなる虞がある。 The diameter of the fibrous material may be equal to or less than the thickness of the heat resistant porous membrane, but is preferably 0.01 to 5 μm, for example. If the diameter is too large, the entanglement between the fibrous materials will be insufficient, and for example, the effect of improving the strength of the heat-resistant porous membrane by using the fibrous materials may be reduced. On the other hand, if the diameter is too small, the pores of the heat-resistant porous membrane become too small and the ion permeability tends to decrease, and the effect of improving the output characteristics of the battery may be reduced.
　耐熱性多孔質膜中での繊維状物の存在状態は、例えば、長軸（長尺方向の軸）の、耐熱性多孔質膜面に対する角度が平均で３０°以下であることが好ましく、２０°以下であることがより好ましい。 The state of the presence of the fibrous material in the heat resistant porous membrane is, for example, preferably that the angle of the long axis (long axis) with respect to the heat resistant porous membrane surface is 30 ° or less on average, 20 More preferably, it is not more than 0 °.
　耐熱性多孔質膜が前記の繊維状物を含有する場合における耐熱性多孔質膜中の繊維状物の含有量は、繊維状物の使用による作用をより有効に発揮させる観点から、耐熱性多孔質膜の全固形分の全体積中、１０体積％以上であることが好ましく、３０体積％以上であることがより好ましい。他方、前記の繊維状物を含有する耐熱性多孔質膜において、繊維状物の含有量が多すぎると、他の成分（耐熱温度が１５０℃以上の微粒子など）の含有量が少なくなって、これら他の成分による作用が低下することがあるため、繊維状物の含有量は、耐熱性多孔質膜の全固形分の全体積中、８５体積％以下であることが好ましく、７０体積％以下であることがより好ましい。 In the case where the heat-resistant porous membrane contains the fibrous material, the content of the fibrous material in the heat-resistant porous membrane is from the viewpoint of more effectively exerting the action due to the use of the fibrous material. The total volume of the total solid content of the membrane is preferably 10% by volume or more, and more preferably 30% by volume or more. On the other hand, in the heat-resistant porous membrane containing the fibrous material, if the content of the fibrous material is too large, the content of other components (such as fine particles having a heat-resistant temperature of 150 ° C. or higher) is reduced. Since the effect of these other components may be reduced, the content of the fibrous material is preferably 85% by volume or less, and 70% by volume or less in the total volume of the total solid content of the heat-resistant porous membrane. It is more preferable that
　本発明の耐熱性多孔質膜には、シャットダウン機能を付与することができる。シャットダウン機能を有する耐熱性多孔質膜とするには、例えば、８０～１５０℃で溶融する熱溶融性微粒子や、８０～１５０℃の温度下で非水電解液を吸収して膨潤する膨潤性微粒子を含有させる方法が採用できる。 The shutdown function can be imparted to the heat resistant porous membrane of the present invention. In order to obtain a heat-resistant porous film having a shutdown function, for example, hot-melt fine particles that melt at 80 to 150 ° C., or swellable fine particles that swell by absorbing a nonaqueous electrolyte at a temperature of 80 to 150 ° C. The method of containing can be adopted.
　なお、耐熱性多孔質膜における前記のシャットダウン機能は、例えば、モデルセルの温度による抵抗上昇により評価することが可能である。すなわち、正極、負極、耐熱性多孔質膜（正極および負極のうちのいずれか一方と一体化している）、および非水電解液を備えたモデルセルを作製し、このモデルセルを恒温槽中に保持し、５℃／分の速度で昇温しながらモデルセルの内部抵抗値を測定し、測定された内部抵抗値が、加熱前（室温で測定した抵抗値）の５倍以上となる温度を測定することで、この温度を耐熱性多孔質膜の有するシャットダウン温度として評価することができる。 The shutdown function in the heat resistant porous membrane can be evaluated by, for example, an increase in resistance due to the temperature of the model cell. That is, a model cell including a positive electrode, a negative electrode, a heat-resistant porous membrane (integrated with one of the positive electrode and the negative electrode), and a non-aqueous electrolyte is manufactured, and the model cell is placed in a thermostatic bath. Hold and measure the internal resistance value of the model cell while raising the temperature at a rate of 5 ° C./minute, and measure the temperature at which the measured internal resistance value is at least 5 times that before heating (resistance value measured at room temperature). By measuring, this temperature can be evaluated as the shutdown temperature of the heat resistant porous membrane.
　８０～１５０℃で溶融する熱溶融性微粒子、すなわち、日本工業規格（ＪＩＳ）Ｋ　７１２１の規定に準じて、示差走査熱量計（ＤＳＣ）を用いて測定される融解温度が８０～１５０℃の微粒子を含有する耐熱性多孔質膜では、８０～１５０℃（またはそれ以上の温度）に曝されたときに、熱溶融性微粒子が溶融して耐熱性多孔質膜の空孔が閉塞されるため、Ｌｉイオンの移動が阻害される。よって、このような耐熱性多孔質膜を正極と負極との隔離材に用いた非水電池においては、高温時における急激な放電反応が抑制される。この場合、前記の内部抵抗上昇により評価されるセパレータのシャットダウン温度は、熱溶融性微粒子の融点以上１５０℃以下となる。熱溶融性微粒子の融点（前記融解温度）は、１４０℃以下であることがより好ましい。 Heat-melting fine particles that melt at 80 to 150 ° C., that is, fine particles having a melting temperature of 80 to 150 ° C. measured using a differential scanning calorimeter (DSC) in accordance with the provisions of Japanese Industrial Standard (JIS) K 7121 In the heat-resistant porous film containing, when exposed to 80 to 150 ° C. (or higher temperature), the heat-fusible fine particles melt and the pores of the heat-resistant porous film are closed. Li ion migration is inhibited. Therefore, in a non-aqueous battery using such a heat-resistant porous membrane as a separator between the positive electrode and the negative electrode, a rapid discharge reaction at a high temperature is suppressed. In this case, the shutdown temperature of the separator evaluated by the increase in internal resistance is not less than the melting point of the heat-meltable fine particles and not more than 150 ° C. The melting point (the melting temperature) of the heat-meltable fine particles is more preferably 140 ° C. or lower.
　熱溶融性微粒子の構成材料の具体例としては、ポリエチレン（ＰＥ）、エチレン由来の構造単位が８５モル％以上の共重合ポリオレフィン、ＰＰ、またはポリオレフィン誘導体（塩素化ポリエチレン、塩素化ポリプロピレンなど）、ポリオレフィンワックス、石油ワックス、カルナバワックスなどが挙げられる。前記共重合ポリオレフィンとしては、エチレン－ビニルモノマー共重合体、より具体的には、エチレン－酢酸ビニル共重合体（ＥＶＡ）、エチレン－メチルアクリレート共重合体、またはエチレン－エチルアクリレート共重合体が例示できる。また、ポリシクロオレフィンなどを用いることもできる。熱溶融性微粒子は、これらの構成材料の１種のみを有していてもよく、２種以上を有していても構わない。これらの中でも、ＰＥ、ポリオレフィンワックス、またはエチレン由来の構造単位が８５モル％以上のＥＶＡが好適である。また、熱溶融性微粒子は、構成成分として、前記の構成材料の他に、必要に応じて、樹脂に添加される公知の各種添加剤（例えば、酸化防止剤など）を含有していても構わない。 Specific examples of the constituent material of the heat-meltable fine particles include polyethylene (PE), copolymerized polyolefin having a structural unit derived from ethylene of 85 mol% or more, PP, or a polyolefin derivative (chlorinated polyethylene, chlorinated polypropylene, etc.), polyolefin Examples thereof include wax, petroleum wax, carnauba wax and the like. Examples of the copolymer polyolefin include an ethylene-vinyl monomer copolymer, more specifically, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer, or an ethylene-ethyl acrylate copolymer. it can. Moreover, polycycloolefin etc. can also be used. The heat-meltable fine particles may have only one kind of these constituent materials, or may have two or more kinds. Among these, PE, polyolefin wax, or EVA having a structural unit derived from ethylene of 85 mol% or more is preferable. Further, the heat-meltable fine particles may contain various known additives (for example, antioxidants) added to the resin as necessary, in addition to the above-described constituent materials. Absent.
　熱溶融性微粒子の粒子径としては、前述の耐熱温度が１５０℃以上の微粒子と同じ測定法で測定される数平均粒子径で、例えば、０．００１μｍ以上であることが好ましく、０．１μｍ以上であることがより好ましく、また、１５μｍ以下であることが好ましく、１μｍ以下であることがより好ましい。 The particle diameter of the heat-meltable fine particles is a number average particle diameter measured by the same measurement method as that of the fine particles having the heat-resistant temperature of 150 ° C. or more, and is preferably 0.001 μm or more, for example, 0.1 μm or more. More preferably, it is preferably 15 μm or less, and more preferably 1 μm or less.
　８０～１５０℃の温度下で非水電解液を吸収して膨潤する膨潤性微粒子を有する耐熱性多孔質膜では、電池内で高温に曝されたときに、膨潤性微粒子が非水電解液を吸収して大きく膨張する（以下、膨潤性微粒子における温度の上昇に伴って非水電解液を吸収し大きく膨張する機能を「熱膨潤性」という）ことにより、耐熱性多孔質膜内のＬｉイオンの伝導性を著しく低下させるため、電池の内部抵抗が上昇し、前記のシャットダウン機能を確実に確保することが可能となる。 In a heat-resistant porous membrane having swellable fine particles that swell by absorbing a non-aqueous electrolyte at a temperature of 80 to 150 ° C., the swellable fine particles do not form a non-aqueous electrolyte when exposed to high temperatures in the battery. Li ion in the heat-resistant porous membrane by absorbing and expanding greatly (hereinafter referred to as “heat-swelling”). Therefore, the internal resistance of the battery is increased, and the shutdown function can be reliably ensured.
　このような熱膨潤性を有する膨潤性微粒子としては、例えば、架橋ポリスチレン（ＰＳ）、架橋アクリル樹脂［例えば、架橋ポリメチルメタクリレート（ＰＭＭＡ）］、架橋フッ素樹脂［例えば、架橋ポリフッ化ビニリデン（ＰＶＤＦ）］などが好適であり、架橋ＰＭＭＡが特に好ましい。 Examples of such swellable fine particles having thermal swellability include crosslinked polystyrene (PS), crosslinked acrylic resin [for example, crosslinked polymethyl methacrylate (PMMA)], and crosslinked fluororesin [for example, crosslinked polyvinylidene fluoride (PVDF). ] Is preferred, and cross-linked PMMA is particularly preferred.
　膨潤性微粒子の粒子径は、レーザー散乱粒度分布計（例えば、ＨＯＲＩＢＡ社製「ＬＡ－９２０」）を用い、微粒子を膨潤しない媒体（例えば水）に分散させて測定した数平均粒子径で、０．１～２０μｍであることが好ましい。 The particle diameter of the swellable fine particles is a number average particle diameter measured by dispersing the fine particles in a non-swelling medium (for example, water) using a laser scattering particle size distribution analyzer (for example, “LA-920” manufactured by HORIBA). It is preferably 1 to 20 μm.
　膨潤性微粒子の市販品としては、例えば、ガンツ化成社製の架橋ＰＭＭＡ「ガンツパール（製品名）」、東洋インキ社製の架橋ＰＭＭＡ「ＲＳＰ１０７９（製品名）」などが入手可能である。 As commercially available products of swellable fine particles, for example, cross-linked PMMA “Gantz Pearl (product name)” manufactured by Ganz Kasei Co., Ltd., and cross-linked PMMA “RSP1079 (product name)” manufactured by Toyo Ink Co., Ltd. are available.
　耐熱性多孔質膜にシャットダウン機能を持たせるには、熱溶融性微粒子のみを含有させてもよく、膨潤性微粒子のみを含有させてもよく、熱溶融性微粒子と膨潤性微粒子の両者を含有させてもよい。また、膨潤性微粒子をコアとし、その表面を熱溶融性微粒子の構成材料で覆ったコアシェル型の微粒子のような、熱溶融性微粒子の構成材料と膨潤性微粒子の構成材料との複合体微粒子を耐熱性多孔質膜に含有させてもよい。 In order to give the heat-resistant porous membrane a shutdown function, it may contain only hot-melt fine particles, may contain only swellable fine particles, or contain both hot-melt fine particles and swellable fine particles. May be. Also, composite fine particles of a constituent material of a heat-fusible fine particle and a constituent material of a swellable fine particle such as a core-shell type fine particle having a swellable fine particle as a core and the surface thereof covered with the constituent material of a heat-fusible fine particle You may make it contain in a heat resistant porous membrane.
　熱溶融性微粒子や膨潤性微粒子を耐熱性多孔質膜に含有させることでシャットダウン機能を持たせる場合、良好なシャットダウン機能を確保する点からは、耐熱性多孔質膜中における熱溶融性微粒子または膨潤性微粒子の含有量（耐熱性多孔質膜が、熱溶融性微粒子と膨潤性微粒子との両者を含有する場合は、その合計量であり、熱溶融性微粒子の構成材料と膨潤性微粒子の構成材料との複合体微粒子を含有する場合は、その量。耐熱性多孔質膜中における熱溶融性微粒子または膨潤性微粒子の含有量について、以下同じ。）は、耐熱性多孔質膜の全固形分の全体積中、５～７０体積％であることが好ましい。これらの微粒子の含有量が少なすぎると、これらを含有させることによるシャットダウン効果が小さくなることがあり、多すぎると、耐熱性多孔質膜中における耐熱温度が１５０℃以上の微粒子や繊維状物などの含有量が減ることになるため、これらによって確保される効果が小さくなることがある。 When a heat-resistant porous film contains a heat-meltable fine particle or a swellable fine particle to provide a shutdown function, the heat-meltable fine particle or swelling in the heat-resistant porous film is required to ensure a good shutdown function. Content of heat-soluble fine particles (when the heat-resistant porous film contains both heat-meltable fine particles and swellable fine particles, the total amount thereof is obtained. The amount of the heat-meltable fine particles or the swellable fine particles in the heat-resistant porous membrane is the same hereinafter.) Is the total solid content of the heat-resistant porous membrane. The total volume is preferably 5 to 70% by volume. If the content of these fine particles is too small, the shutdown effect due to the inclusion of these may be reduced, and if too large, the heat resistant temperature in the heat-resistant porous membrane is fine particles or fibrous materials having a heat resistance temperature of 150 ° C. or higher. Therefore, the effect secured by these may be reduced.
　本発明の耐熱性多孔質膜の具体的な態様としては、例えば、下記（ａ）、（ｂ）および（ｃ）の態様が挙げられる。
（ａ）耐熱温度が１５０℃以上の微粒子（および必要に応じてその他の微粒子）が有機バインダにより結着されて形成されたシート状の耐熱性多孔質膜。
（ｂ）耐熱温度が１５０℃以上の微粒子と繊維状物（更には、必要に応じてその他の微粒子）とが均一に分散し、これらが有機バインダにより結着されて形成されたシート状の耐熱性多孔質膜。
（ｃ）繊維状物が多数集合して、これらのみによりシート状物を形成しているもの、例えば、織布、不織布（紙を含む）といった形態のものを用い、このシート状物中に耐熱温度が１５０℃以上の微粒子や必要に応じてその他の微粒子を含有させ、有機バインダによってシート状物に係る繊維状物と各種微粒子などを結着することで構成した単一層からなる耐熱性多孔質膜。 Specific embodiments of the heat resistant porous membrane of the present invention include the following embodiments (a), (b) and (c).
(A) A sheet-like heat-resistant porous film formed by binding fine particles (and other fine particles if necessary) having a heat-resistant temperature of 150 ° C. or higher with an organic binder.
(B) Sheet-like heat-resistant formed by uniformly dispersing fine particles having a heat-resistant temperature of 150 ° C. or more and fibrous materials (and, if necessary, other fine particles) and binding them with an organic binder. Porous membrane.
(C) A material in which a large number of fibrous materials are aggregated to form a sheet-like material only, for example, a woven fabric or a nonwoven fabric (including paper) is used. Heat-resistant porous material composed of a single layer composed of fine particles having a temperature of 150 ° C. or higher and other fine particles as necessary, and binding the fibrous material related to the sheet-like material and various fine particles with an organic binder film.
　このような態様の耐熱性多孔質膜は、非水電池に使用される電極（正極および／または負極）と一体化され、正極と負極とを仕切る隔離材として用いられる。 Such a heat-resistant porous membrane is integrated with an electrode (positive electrode and / or negative electrode) used in a nonaqueous battery, and used as a separator for separating the positive electrode and the negative electrode.
　よって、本発明の耐熱性多孔質膜を形成し、電極と一体化するに当たっては、例えば、（ａ）および（ｂ）の態様の耐熱性多孔質膜については、耐熱温度が１５０℃以上の微粒子および有機バインダ、更には、必要に応じて繊維状物およびその他の微粒子を含み、これらを溶媒（分散媒を含む。以下同じ。）に分散させて耐熱性多孔質膜形成用組成物を調製し（有機バインダについては溶媒に溶解しているものを用いてもよい）、これを電極の表面に塗布し、乾燥して電極表面に耐熱性多孔質膜を直接形成する方法が採用できる。 Therefore, when the heat-resistant porous film of the present invention is formed and integrated with the electrode, for example, for the heat-resistant porous film of the embodiments (a) and (b), the heat-resistant temperature is 150 ° C. or more. In addition, an organic binder and, if necessary, a fibrous material and other fine particles are dispersed in a solvent (including a dispersion medium; the same shall apply hereinafter) to prepare a heat-resistant porous film-forming composition. (The organic binder may be dissolved in a solvent may be used), and this may be applied to the electrode surface and dried to directly form a heat resistant porous film on the electrode surface.
　また、ＰＥＴフィルムや金属板などの基材に前記の耐熱性多孔質膜形成用組成物を塗布し、乾燥して（ａ）や（ｂ）の態様の耐熱性多孔質膜を形成し、これを基材から剥離した後に電極と重ね合わせ、ロールプレスなどにより電極と一体化してもよい。 In addition, the heat-resistant porous film-forming composition is applied to a substrate such as a PET film or a metal plate, and dried to form the heat-resistant porous film of the aspect (a) or (b). After being peeled from the substrate, it may be superposed on the electrode and integrated with the electrode by a roll press or the like.
　また、（ｃ）の態様の耐熱性多孔質膜を形成するには、繊維状物のシート状物に、前記の耐熱性多孔質膜形成用組成物を含浸させ、一定のギャップを通して不要な組成物を除去した後、乾燥して独立膜の耐熱性多孔質膜を得ることができる。なお、この耐熱性多孔質膜は、その後、電極と重ね合わせ、ロールプレスなどにより電極と一体化する。 In addition, in order to form the heat-resistant porous film of the aspect (c), a fibrous sheet-like material is impregnated with the heat-resistant porous film-forming composition, and an unnecessary composition is passed through a certain gap. After removing the matter, it can be dried to obtain an independent heat-resistant porous membrane. The heat-resistant porous film is then overlapped with the electrode and integrated with the electrode by a roll press or the like.
　（ｃ）の態様の耐熱性多孔質膜で使用する繊維状物のシート状物としては、前記例示の各材料を構成成分に含む繊維状物の少なくとも１種で構成される織布や、これら繊維状物同士が絡み合った構造を有する不織布などの多孔質シートなどが挙げられる。より具体的には、紙、ＰＰ不織布、ポリエステル不織布（ＰＥＴ不織布、ＰＥＮ不織布、ＰＢＴ不織布など）、ＰＡＮ不織布などの不織布などが例示できる。 Examples of the fibrous sheet used in the heat-resistant porous membrane of the aspect (c) include a woven fabric composed of at least one fibrous substance containing the above-mentioned exemplified materials as constituent components, and these Examples thereof include a porous sheet such as a nonwoven fabric having a structure in which fibrous materials are entangled with each other. More specifically, non-woven fabrics such as paper, PP non-woven fabric, polyester non-woven fabric (PET non-woven fabric, PEN non-woven fabric, PBT non-woven fabric, etc.) and PAN non-woven fabric can be exemplified.
　耐熱性多孔質膜形成用組成物に用いられる溶媒は、耐熱温度が１５０℃以上の微粒子や熱溶融性微粒子、膨潤性微粒子などを均一に分散でき、また、有機バインダを均一に溶解または分散できるものであればよいが、例えば、トルエンなどの芳香族炭化水素；テトラヒドロフランなどのフラン類；メチルエチルケトン、メチルイソブチルケトンなどのケトン類；などの有機溶媒が好適である。なお、これらの溶媒に、界面張力を制御する目的で、アルコール（エチレングリコール、プロピレングリコールなど）、または、モノメチルアセテートなどの各種プロピレンオキサイド系グリコールエーテルなどを適宜添加しても良い。また、バインダが水溶性である場合、エマルジョンとして使用する場合などでは、水を溶媒としてもよく、この際にもアルコール類（メチルアルコール、エチルアルコール、イソプロピルアルコール、エチレングリコールなど）を適宜加えて界面張力を制御することもできる。 The solvent used in the composition for forming a heat-resistant porous film can uniformly disperse fine particles having a heat-resistant temperature of 150 ° C. or more, heat-meltable fine particles, swellable fine particles, and can uniformly dissolve or disperse the organic binder. Any organic solvent may be used, for example, aromatic hydrocarbons such as toluene; furans such as tetrahydrofuran; ketones such as methyl ethyl ketone and methyl isobutyl ketone; In addition, for the purpose of controlling the interfacial tension, alcohols (ethylene glycol, propylene glycol, etc.) or various propylene oxide glycol ethers such as monomethyl acetate may be appropriately added to these solvents. In addition, when the binder is water-soluble or used as an emulsion, water may be used as a solvent. In this case, an alcohol (methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.) is added as appropriate to the interface. The tension can also be controlled.
　前記の耐熱性多孔質膜形成用組成物では、耐熱温度が１５０℃以上の微粒子、有機バインダ、熱溶融性微粒子、膨潤性微粒子、繊維状物などを含む固形分含量を、例えば１０～８０質量％とすることが好ましい。 In the composition for forming a heat resistant porous film, the solid content including fine particles having an heat resistant temperature of 150 ° C. or higher, an organic binder, hot melt fine particles, swellable fine particles, fibrous materials, etc., for example, 10 to 80 mass. % Is preferable.
　耐熱温度が１５０℃以上の微粒子に板状粒子を用いた場合、耐熱性多孔質膜中における板状粒子の配向性を高めるには、耐熱性多孔質膜形成用組成物を電極表面やその他の基材表面に塗布した塗膜（乾燥前の塗膜）や、耐熱性多孔質膜形成用組成物を含浸させたシート状物において、これらの組成物にシェアをかければよい。例えば、耐熱温度が１５０℃以上の微粒子などをシート状物の空孔内に存在させる方法として上述した耐熱性多孔質膜形成用組成物をシート状物に含浸させた後、一定のギャップを通す方法により、耐熱性多孔質膜形成用組成物にシェアをかけることが可能であり、これにより、板状粒子の配向性を高めることができる。 In the case where plate-like particles are used as fine particles having a heat-resistant temperature of 150 ° C. or higher, in order to increase the orientation of the plate-like particles in the heat-resistant porous film, the composition for forming a heat-resistant porous film is applied to the electrode surface or other In a coated film (coated film before drying) applied to the substrate surface or a sheet-like material impregnated with a heat-resistant porous film-forming composition, these compositions may be shared. For example, after impregnating the above-mentioned composition for forming a heat-resistant porous film as a method for allowing fine particles having a heat-resistant temperature of 150 ° C. or more to exist in the pores of the sheet-like material, a certain gap is passed through. By the method, it is possible to apply a share to the composition for forming a heat-resistant porous film, whereby the orientation of the plate-like particles can be increased.
　また、耐熱性多孔質膜中において、板状の、耐熱温度が１５０℃以上の微粒子の配向性をより高めるには、前記のシェアをかける方法以外にも、高固形分濃度（例えば５０～８０質量％）の耐熱性多孔質膜形成用組成物を使用する方法；耐熱温度が１５０℃以上の微粒子を、ディスパー、アジター、ホモジナイザー、ボールミル、アトライター、ジェットミルなどの各種混合・攪拌装置、分散装置などを用いて溶媒に分散させ、得られた分散体に有機バインダ（更に、必要に応じて繊維状物、熱溶融性微粒子、膨潤性微粒子など）を添加・混合して調製した耐熱性多孔質膜形成用組成物を使用する方法；表面に油脂類、界面活性剤、シランカップリング剤などの分散性剤を作用させて、表面を改質した耐熱温度が１５０℃以上の微粒子を用いて調製した耐熱性多孔質膜形成用組成物を使用する方法；形状、径またはアスペクト比の異なる耐熱温度が１５０℃以上の微粒子を併用して調製した耐熱性多孔質膜形成用組成物を使用する方法；耐熱性多孔質膜形成用組成物をシート状物に含浸させたり、基材上に塗布したりした後の乾燥条件を制御する方法；耐熱性多孔質膜を加圧や加熱加圧プレスする方法；耐熱性多孔質膜形成用組成物をシート状物に含浸させたり、基材上に塗布したりした後、乾燥前に磁場をかける方法；などが採用でき、これらの方法をそれぞれ単独で実施してもよく、２種以上の方法を組み合わせて実施してもよい。 Further, in order to further enhance the orientation of the plate-like fine particles having a heat-resistant temperature of 150 ° C. or higher in the heat-resistant porous film, a high solid content concentration (for example, 50-80 Mass%) heat-resistant porous film-forming composition; fine particles having a heat-resistant temperature of 150 ° C. or higher, various mixing / stirring devices such as dispersers, agitators, homogenizers, ball mills, attritors, jet mills, dispersions Heat-resistant porous material prepared by dispersing in an organic solvent using an apparatus and adding and mixing organic binders (further, if necessary, fibrous materials, heat-meltable fine particles, swellable fine particles, etc.). A method of using a composition for forming a membrane; using fine particles having a heat resistance of 150 ° C. or higher, which is modified by applying a dispersing agent such as fats and oils, surfactants, and silane coupling agents on the surface Using a composition for forming a heat-resistant porous film prepared by using a composition for forming a heat-resistant porous film prepared using a combination of fine particles having a heat-resistant temperature of 150 ° C. or more having different shapes, diameters or aspect ratios Method for controlling the drying conditions after impregnating the composition for forming a heat-resistant porous film into a sheet or coating on a substrate; pressurizing or heat-pressing the heat-resistant porous film A method of pressing; a method of impregnating a heat-resistant porous film-forming composition into a sheet-like material, or applying a magnetic field before drying after coating on a substrate; and the like can be employed. It may be carried out alone or in combination of two or more methods.
　こうして得られる耐熱性多孔質膜の厚みは、これが使用される電池の短絡防止効果をより高め、また、耐熱性多孔質膜の強度を高める観点から、例えば、３μｍ以上とすることが好ましく、５μｍ以上とすることがより好ましい。他方、電池のエネルギー密度をより高める観点からは、耐熱性多孔質膜の厚みは、５０μｍ以下とすることが好ましく、３０μｍ以下とすることがより好ましい。 The thickness of the heat-resistant porous membrane thus obtained is preferably 3 μm or more, for example, from the viewpoint of further enhancing the short-circuit prevention effect of the battery in which it is used and increasing the strength of the heat-resistant porous membrane. More preferably. On the other hand, from the viewpoint of further increasing the energy density of the battery, the thickness of the heat-resistant porous film is preferably 50 μm or less, and more preferably 30 μm or less.
　また、耐熱性多孔質膜の空孔率は、非水電解質の保液量を確保してイオン透過性を良好にするために、乾燥した状態で、２０％以上であることが好ましく、３０％以上であることがより好ましい。一方、耐熱性多孔質膜の強度確保と電池における内部短絡の防止の観点から、耐熱性多孔質膜の空孔率は、乾燥した状態で、７０％以下であることが好ましく、６０％以下であることがより好ましい。なお、耐熱性多孔質膜の空孔率：Ｐ（％）は、耐熱性多孔質膜の厚み、面積あたりの質量、構成成分の密度から、下記式（２）を用いて各成分ｉについての総和を求めることにより計算できる。 In addition, the porosity of the heat resistant porous membrane is preferably 20% or more in a dry state in order to secure the liquid retention amount of the nonaqueous electrolyte and improve the ion permeability, and preferably 30% More preferably. On the other hand, from the viewpoint of securing the strength of the heat resistant porous membrane and preventing internal short circuit in the battery, the porosity of the heat resistant porous membrane is preferably 70% or less in a dry state, and is 60% or less. More preferably. The porosity of the heat-resistant porous membrane: P (%) is calculated from the thickness of the heat-resistant porous membrane, the mass per area, and the density of the constituent components for each component i using the following formula (2). It can be calculated by calculating the sum.
　Ｐ＝｛１－（ｍ／ｔ）／（Σａｉ・ρｉ）｝×１００　　　　　（２）
　ここで、前記式（２）中、ａｉ：全体の質量を１としたときの成分ｉの比率、ρｉ：成分ｉの密度（ｇ／ｃｍ３）、ｍ：耐熱性多孔質膜の単位面積あたりの質量（ｇ／ｃｍ２）、ｔ：耐熱性多孔質膜の厚み（ｃｍ）、である。 P = {1- (m / t) / (Σa i · ρ i )} × 100 (2)
Here, in the formula (2), a i : ratio of component i when the total mass is 1, ρ i : density of component i (g / cm 3 ), m: unit of heat-resistant porous membrane The mass per area (g / cm 2 ), t: the thickness (cm) of the heat-resistant porous membrane.
　更に、後記の実施例で示す方法により求められる耐熱性多孔質膜の１５０℃での熱収縮率（電極と一体化された状態での熱収縮率）は、５％以下であることが好ましい。 Furthermore, the heat shrinkage rate at 150 ° C. (heat shrinkage rate in an integrated state with the electrode) of the heat-resistant porous membrane obtained by the method described in the examples below is preferably 5% or less.
　また、耐熱性多孔質膜の強度としては、直径が１ｍｍのニードルを用いた突き刺し強度で５０ｇ以上であることが望ましい。かかる突き刺し強度が小さすぎると、リチウムのデンドライト結晶が発生した場合に、耐熱性多孔質膜の突き破れによる短絡が発生する虞がある。 Also, the strength of the heat resistant porous membrane is desirably 50 g or more in terms of puncture strength using a needle having a diameter of 1 mm. If the piercing strength is too small, there is a possibility that a short circuit occurs due to the piercing of the heat-resistant porous film when lithium dendrite crystals are generated.
　更に、耐熱性多孔質膜の透気度は、ＪＩＳ　Ｐ　８１１７に準拠した方法で測定され、０．８７９ｇ／ｍｍ２の圧力下で１００ｍｌの空気が膜を透過する秒数で示されるガーレー値で１０～３００ｓｅｃであることが望ましい。透気度が大きすぎると、イオン透過性が小さくなり、小さすぎると耐熱性多孔質膜の強度が小さくなることがある。 Further, the air permeability of the heat-resistant porous membrane is measured by a method according to JIS P 8117, and is a Gurley value indicated by the number of seconds that 100 ml of air permeates the membrane under a pressure of 0.879 g / mm 2. 10 to 300 sec is desirable. If the air permeability is too high, the ion permeability is reduced, and if it is too low, the strength of the heat resistant porous membrane may be reduced.
　これまでに説明した構成の耐熱性多孔質膜とすることで、前記の熱収縮率や強度、透気度を確保することができる。 The heat shrinkage rate, strength, and air permeability described above can be ensured by using the heat-resistant porous membrane having the configuration described so far.
　次に、本発明の非水電池用セパレータについて説明する。本発明の非水電池用セパレータは、多孔質基材と本発明の耐熱性多孔質膜とが一体化されて構成された多層構造のセパレータである。 Next, the nonaqueous battery separator of the present invention will be described. The separator for non-aqueous batteries of the present invention is a separator having a multilayer structure in which a porous substrate and the heat-resistant porous membrane of the present invention are integrated.
　セパレータに係る多孔質基材としては、樹脂製の不織布、織布、微多孔膜などを用いることができる。 As the porous base material related to the separator, a resin nonwoven fabric, woven fabric, microporous film, or the like can be used.
　本発明のセパレータにシャットダウン機能を付与する場合には、多孔質基材の構成樹脂に、融点が８０～１５０℃の熱可塑性樹脂を用いることが好ましい。融点が８０～１５０℃の熱可塑性樹脂としては、熱溶融性微粒子の構成樹脂として先に例示した各種熱可塑性樹脂が挙げられる。このような熱可塑性樹脂で構成される多孔質基材の中でも、ポリオレフィン（ＰＥ、エチレン－プロピレン共重合体など）製の微多孔膜が好ましい。 When a shutdown function is imparted to the separator of the present invention, it is preferable to use a thermoplastic resin having a melting point of 80 to 150 ° C. as the constituent resin of the porous substrate. Examples of the thermoplastic resin having a melting point of 80 to 150 ° C. include various thermoplastic resins exemplified above as the constituent resin of the heat-meltable fine particles. Among the porous substrates composed of such thermoplastic resins, microporous membranes made of polyolefin (PE, ethylene-propylene copolymer, etc.) are preferable.
　本発明のセパレータにおけるシャットダウン機能も、耐熱性多孔質膜のシャットダウン機能と同様に、モデルセルの温度による抵抗上昇により評価することが可能である。すなわち、正極、負極、セパレータおよび非水電解液を備えたモデルセルを作製し、このモデルセルを恒温槽中に保持し、５℃／分の速度で昇温しながらモデルセルの内部抵抗値を測定し、測定された内部抵抗値が、加熱前（室温で測定した抵抗値）の５倍以上となる温度を測定することで、この温度をセパレータの有するシャットダウン温度として評価することができる。 The shutdown function in the separator of the present invention can also be evaluated by the resistance increase due to the temperature of the model cell, similar to the shutdown function of the heat-resistant porous film. That is, a model cell including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte is prepared, and the model cell is held in a thermostatic bath, and the internal resistance value of the model cell is set while increasing the temperature at a rate of 5 ° C./min. By measuring and measuring the temperature at which the measured internal resistance value is at least five times that before heating (resistance value measured at room temperature), this temperature can be evaluated as the shutdown temperature of the separator.
　他方、セパレータの耐熱性を重視して、シャットダウン機能を付与しない場合には、耐熱性樹脂で構成された多孔質基材を用いることもできる。このような耐熱性樹脂としては、耐熱温度が１５０℃以上で、電池に用いる非水電解質に対して安定であり、更に電池内部での酸化還元反応に対して安定である樹脂であればいずれでもよい。より具体的には、ポリイミド、ポリアミドイミド、アラミド、ポリテトラフルオロエチレン、ポリスルホン、ポリウレタン、ＰＡＮ、ポリエステル（ＰＥＴ、ＰＢＴ、ＰＥＮなど）などの耐熱性樹脂が挙げられる。 On the other hand, when the heat resistance of the separator is emphasized and the shutdown function is not given, a porous substrate made of a heat resistant resin can be used. As such a heat-resistant resin, any resin that has a heat-resistant temperature of 150 ° C. or more, is stable with respect to the nonaqueous electrolyte used in the battery, and is stable with respect to the oxidation-reduction reaction inside the battery. Good. More specifically, heat-resistant resins such as polyimide, polyamideimide, aramid, polytetrafluoroethylene, polysulfone, polyurethane, PAN, polyester (PET, PBT, PEN, etc.) can be mentioned.
　多孔質基材として使用される微多孔膜には、前記の熱可塑性樹脂により構成されるもの、前記の耐熱性樹脂により構成されるもののいずれにおいても、従来公知の方法によって製造されたものを用いることができる。例えば、溶剤抽出法、乾式または湿式延伸（１軸または２軸延伸）法などにより作製されたイオン透過性の多孔質フィルムを用いることができる。また、薬剤や超臨界ＣＯ２などを用いた発泡法により微多孔化したフィルムを用いることもできる。 As the microporous membrane used as the porous substrate, any of the above-described thermoplastic resin and the above-mentioned heat-resistant resin, manufactured by a conventionally known method, is used. be able to. For example, an ion-permeable porous film produced by a solvent extraction method, a dry or wet stretching (uniaxial or biaxial stretching) method, or the like can be used. In addition, a film microporous by a foaming method using a drug, supercritical CO 2 or the like can also be used.
　本発明のセパレータを製造するにあたっては、耐熱性多孔質膜の形成の際に使用される前記の耐熱性多孔質膜形成用組成物を、多孔質基材の表面に塗布し、乾燥する工程を経て、多孔質基材の表面に耐熱性多孔質膜からなる層を形成する方法が採用できる。また、先に例示した独立膜の耐熱性多孔質膜を形成する方法によって得られた耐熱性多孔質膜と、多孔質基材とを重ね、ロールプレスなどにより一体化してもよい。 In producing the separator of the present invention, the step of applying the heat-resistant porous film forming composition used in the formation of the heat-resistant porous film to the surface of the porous substrate and drying it is performed. Then, the method of forming the layer which consists of a heat resistant porous film on the surface of a porous base material is employable. Further, the heat-resistant porous film obtained by the method for forming the heat-resistant porous film of the independent film exemplified above and the porous base material may be stacked and integrated by a roll press or the like.
　耐熱性多孔質膜を形成する際に耐熱温度が１５０℃以上の微粒子に板状粒子を用いた場合において、その配向性を高めるには、耐熱性多孔質膜において板状粒子の配向性を高める方法として先に例示した各種方法を用いることができる。 In the case where plate-like particles are used as fine particles having a heat-resistant temperature of 150 ° C. or higher when forming the heat-resistant porous film, the orientation of the plate-like particles is increased in the heat-resistant porous film. As the method, various methods exemplified above can be used.
　本発明のセパレータにおいて、耐熱性多孔質膜と多孔質基材とは、それぞれ１枚ずつである必要はなく、複数枚でセパレータを構成していてもよい。例えば、耐熱性多孔質膜の両面に多孔質基材を配置した構成としたり、多孔質基材の両面に耐熱性多孔質膜を配置した構成としてもよい。ただし、耐熱性多孔質膜と多孔質基材との合計枚数を増やしすぎると、セパレータの厚みを増やして電池の内部抵抗の増加やエネルギー密度の低下を招く虞があるので好ましくなく、セパレータ中の耐熱性多孔質膜と多孔質基材との合計枚数は５枚以下であることが好ましい。 In the separator of the present invention, the heat-resistant porous membrane and the porous substrate do not have to be one each, and a plurality of separators may be configured. For example, it is good also as a structure which has arrange | positioned the porous base material on both surfaces of a heat resistant porous film, or the structure which has arrange | positioned the heat resistant porous film on both surfaces of a porous base material. However, if the total number of the heat-resistant porous membrane and the porous substrate is increased too much, it is not preferable because the thickness of the separator is increased, which may increase the internal resistance of the battery and decrease the energy density. The total number of the heat-resistant porous membrane and the porous substrate is preferably 5 or less.
　このようにして得られる本発明のセパレータにおいては、電池の短絡防止効果をより高め、セパレータの強度を確保して、その取り扱い性を良好とする観点から、その厚みは、例えば、５．５μｍ以上とすることが好ましく、１０μｍ以上とすることがより好ましい。他方、電池のエネルギー密度をより高める観点からは、セパレータの厚みは、５０μｍ以下とすることが好ましく、３０μｍ以下とすることがより好ましい。 In the separator of the present invention thus obtained, the thickness is, for example, 5.5 μm or more from the viewpoint of further enhancing the short-circuit preventing effect of the battery, ensuring the strength of the separator, and improving its handleability. Preferably, the thickness is 10 μm or more. On the other hand, from the viewpoint of further increasing the energy density of the battery, the thickness of the separator is preferably 50 μm or less, and more preferably 30 μm or less.
　また、本発明のセパレータにおいては、耐熱性多孔質膜の厚みをＸ（μｍ）、多孔質基材の厚みをＹ（μｍ）としたとき、ＸとＹとの比率Ｙ／Ｘを１～２０としつつ、セパレータ全体の厚みが前記好適値を満足するようにすることが好ましい。Ｙ／Ｘが大きすぎると、耐熱性多孔質膜が薄くなりすぎて、例えば、高温時での寸法安定性が劣る多孔質基材を用いた場合に、その熱収縮を抑制する効果が小さくなる虞がある。また、Ｙ／Ｘが小さすぎると、耐熱性多孔質膜が厚くなりすぎて、セパレータ全体の厚みを増大させ、出力特性の向上効果が小さくなる虞があるなど、電池特性の低下を引き起こすことがある。なお、セパレータが、耐熱性多孔質膜を複数枚有する場合には、厚みＸはその総厚みであり、多孔質基材を複数枚有する場合には、厚みＹはその総厚みである。 In the separator of the present invention, when the thickness of the heat-resistant porous film is X (μm) and the thickness of the porous substrate is Y (μm), the ratio Y / X of X to Y is 1 to 20 However, it is preferable that the thickness of the entire separator satisfies the preferable value. When Y / X is too large, the heat-resistant porous film becomes too thin, and, for example, when a porous substrate having poor dimensional stability at high temperatures is used, the effect of suppressing the thermal shrinkage becomes small. There is a fear. On the other hand, if Y / X is too small, the heat-resistant porous film becomes too thick, which increases the thickness of the entire separator and may cause a decrease in output characteristics, resulting in a decrease in battery characteristics. is there. When the separator has a plurality of heat-resistant porous films, the thickness X is the total thickness, and when the separator has a plurality of porous substrates, the thickness Y is the total thickness.
　具体的な値で表現すると、多孔質基材の厚み（セパレータが多孔質基材を複数枚有する場合には、その総厚み）は、５μｍ以上であることが好ましく、また、３０μｍ以下であることが好ましい。そして、耐熱性多孔質膜の厚み（セパレータが耐熱性多孔質膜を複数枚有する場合には、その総厚み）は、０．５μｍ以上であることが好ましく、１μｍ以上であることがより好ましく、２μｍ以上であることが更に好ましく、また、１０μｍ以下であることが好ましく、５μｍ以下であることがより好ましく、３μｍ以下であることが更に好ましい。 In terms of specific values, the thickness of the porous substrate (when the separator has a plurality of porous substrates, the total thickness) is preferably 5 μm or more, and 30 μm or less. Is preferred. And the thickness of the heat resistant porous membrane (when the separator has a plurality of heat resistant porous membranes, the total thickness) is preferably 0.5 μm or more, more preferably 1 μm or more, More preferably, it is 2 μm or more, preferably 10 μm or less, more preferably 5 μm or less, and further preferably 3 μm or less.
　また、前記式（２）を用い、ｍをセパレータの単位面積あたりの質量（ｇ／ｃｍ２）とし、ｔをセパレータの厚み（ｃｍ）として求められるセパレータの空孔率は、非水電解質の保液量を確保してイオン透過性を良好にするために、乾燥した状態で、２０％以上であることが好ましく、３０％以上であることがより好ましい。一方、セパレータの強度確保と内部短絡の防止の観点から、前記方法により求められるセパレータの空孔率は、乾燥した状態で、７０％以下であることが好ましく、６０％以下であることがより好ましい。 Further, the porosity of the separator obtained by using the above formula (2), where m is the mass per unit area (g / cm 2 ) of the separator and t is the thickness (cm) of the separator, is the retention of the non-aqueous electrolyte. In order to secure the liquid amount and improve the ion permeability, it is preferably 20% or more, more preferably 30% or more in the dried state. On the other hand, from the viewpoint of securing the strength of the separator and preventing internal short circuit, the porosity of the separator obtained by the above method is preferably 70% or less and more preferably 60% or less in a dry state. .
　更に、前記式（２）を用い、ｍを多孔質基材の単位面積あたりの質量（ｇ／ｃｍ２）とし、ｔを多孔質基材の厚み（ｃｍ）として求められるセパレータに係る多孔質基材の空孔率は３０～７０％であることが好ましい。また、前記式（２）により求められるセパレータに係る耐熱性多孔質膜の空孔率は、電極と一体化される耐熱性多孔質膜の場合と同様に、２０％以上（より好ましくは３０％以上）、７０％以下（より好ましくは６０％以下）であることが好ましい。 Further, using the above formula (2), m is the mass per unit area (g / cm 2 ) of the porous substrate, and t is the porous substrate according to the separator that is required as the thickness (cm) of the porous substrate. The porosity of the material is preferably 30 to 70%. Further, the porosity of the heat-resistant porous film related to the separator obtained by the above formula (2) is 20% or more (more preferably 30%) as in the case of the heat-resistant porous film integrated with the electrode. Above), 70% or less (more preferably 60% or less).
　後記の実施例で示す方法により求められるセパレータの１５０℃での熱収縮率は、５％以下であることが好ましい。 It is preferable that the thermal shrinkage rate at 150 ° C. of the separator obtained by the method shown in the examples below is 5% or less.
　セパレータの強度としては、直径が１ｍｍのニードルを用いた突き刺し強度で５０ｇ以上であることが望ましい。かかる突き刺し強度が小さすぎると、リチウムのデンドライト結晶が発生した場合に、セパレータの突き破れによる短絡が発生する虞がある。 The strength of the separator is preferably 50 g or more in terms of piercing strength using a needle having a diameter of 1 mm. If the piercing strength is too low, a short circuit may occur due to the breakthrough of the separator when lithium dendrite crystals are generated.
　セパレータの透気度は、ＪＩＳ　Ｐ　８１１７に準拠した方法で測定され、０．８７９ｇ／ｍｍ２の圧力下で１００ｍｌの空気が膜を透過する秒数で示されるガーレー値で１０～３００ｓｅｃであることが望ましい。透気度が大きすぎると、イオン透過性が小さくなり、小さすぎるとセパレータの強度が小さくなることがある。 The air permeability of the separator is measured by a method according to JIS P 8117, and is 100 to 300 sec as a Gurley value indicated by the number of seconds that 100 ml of air passes through the membrane under a pressure of 0.879 g / mm 2. Is desirable. If the air permeability is too high, the ion permeability is reduced, and if it is too low, the strength of the separator may be reduced.
　更に、セパレータのガーレー値は下記式（３）の関係を満たすことが好ましい。 Furthermore, it is preferable that the Gurley value of the separator satisfies the relationship of the following formula (3).
　Ｇｓ≦ｍａｘ｛Ｇａ，Ｇｂ｝＋１０　　　　　　　　（３）
　ここで、Ｇｓ：セパレータのガーレー値、Ｇａ：多孔質基材のガーレー値、Ｇｂ：耐熱性多孔質膜のガーレー値、ｍａｘ｛Ｇａ，Ｇｂ｝：ＧａとＧｂのどちらか大きい方、である。ただし、Ｇｂは、下記式（４）を用いて求める。 Gs ≦ max {Ga, Gb} +10 (3)
Here, Gs: Gurley value of the separator, Ga: Gurley value of the porous substrate, Gb: Gurley value of the heat-resistant porous film, and max {Ga, Gb}: whichever is greater of Ga and Gb. However, Gb is calculated | required using following formula (4).
　Ｇｂ＝Ｇｓ－Ｇａ　　　　　　　　　　　　　　　　（４） Gb = Gs-Ga (4)
　これまでに説明した構成のセパレータとすることで、前記の熱収縮率や強度、透気度を確保することができる。 </ RTI> By using the separator having the configuration described so far, the heat shrinkage rate, strength, and air permeability can be ensured.
　また、前述の耐熱性多孔質膜に関し、本発明の耐熱性多孔質膜と電極との一体化物、および本発明のセパレータにおいては、耐熱性多孔質膜の１８０°の剥離強度が０．６Ｎ／ｃｍ以上であることが好ましく、１．０Ｎ／ｃｍ以上であることが更に好ましい。これまでに説明した構成の耐熱性多孔質膜およびセパレータとすることで、前記の剥離強度を確保することができる。 In the heat-resistant porous membrane described above, in the integrated body of the heat-resistant porous membrane and the electrode of the present invention and the separator of the present invention, the 180 ° peel strength of the heat-resistant porous membrane is 0.6 N / It is preferably at least cm, and more preferably at least 1.0 N / cm. By using the heat-resistant porous membrane and the separator having the configurations described so far, the above-described peel strength can be ensured.
　ここでいう剥離強度とは、以下の方法により測定される値である。耐熱性多孔質膜と電極との一体化物、またはセパレータから、幅２ｃｍ、長さ５ｃｍの大きさの試験片を切り出し、耐熱性多孔質膜表面の２ｃｍ×２ｃｍの領域に粘着テープを貼り付ける。なお、粘着テープのサイズは幅２ｃｍ、長さ約５ｃｍで、粘着テープの片端と耐熱性多孔質膜の片端が揃うように貼り付ける。その後、引張試験機を用い、試験片の粘着テープを貼り付けた側とは反対側の端と、試験片に貼り付けた粘着テープの試験片に貼り付けた側とは反対側の端とを把持して、引張速度１０ｍｍ／ｍｉｎで引っ張り、耐熱性多孔質膜が剥離した時の強度を測定する。 Here, the peel strength is a value measured by the following method. A test piece having a width of 2 cm and a length of 5 cm is cut out from an integrated product of the heat-resistant porous membrane and the electrode, or a separator, and an adhesive tape is attached to a 2 cm × 2 cm region on the surface of the heat-resistant porous membrane. The pressure-sensitive adhesive tape has a width of 2 cm and a length of about 5 cm, and is attached so that one end of the pressure-sensitive adhesive tape and one end of the heat-resistant porous membrane are aligned. Then, using a tensile tester, the end of the test piece opposite to the side where the adhesive tape was affixed and the end of the adhesive tape affixed to the test piece opposite the end affixed to the test piece Gripping and pulling at a pulling speed of 10 mm / min to measure the strength when the heat-resistant porous film is peeled off.
　続いて、本発明の非水電池について説明する。本発明の非水電池は、本発明の耐熱性多孔質膜が正極および負極の少なくとも一方と一体化され、対極とを仕切る隔離材として使用されているか、本発明のセパレータが正極と負極とを仕切る隔離材として使用されていればよく、その他の構成および構造については特に制限はなく、従来から知られている非水電解質を用いた非水電池（リチウム一次電池などの非水一次電池、リチウム二次電池などの非水二次電池）で採用されている各種構成および構造を適用することができる。以下には、本発明の非水電池のうち、特に主要な形態であるリチウム二次電池について、詳細に説明する。 Subsequently, the nonaqueous battery of the present invention will be described. In the nonaqueous battery of the present invention, the heat-resistant porous membrane of the present invention is integrated with at least one of the positive electrode and the negative electrode and used as a separator to separate the counter electrode, or the separator of the present invention has a positive electrode and a negative electrode. Any other configuration and structure may be used as long as it is used as a separating material, and non-aqueous batteries using a conventionally known non-aqueous electrolyte (non-aqueous primary batteries such as lithium primary batteries, lithium Various configurations and structures employed in non-aqueous secondary batteries such as secondary batteries can be applied. Below, the lithium secondary battery which is especially a main form among the non-aqueous batteries of this invention is demonstrated in detail.
　リチウム二次電池の形態としては、スチール缶やアルミニウム缶などを外装缶として使用した筒形（角筒形や円筒形など）などが挙げられる。また、金属を蒸着したラミネートフィルムを外装体としたソフトパッケージ電池とすることもできる。 Examples of the form of the lithium secondary battery include a cylindrical shape (such as a rectangular tube shape or a cylindrical shape) using a steel can or an aluminum can as an outer can. Moreover, it can also be set as the soft package battery which used the laminated film which vapor-deposited the metal as an exterior body.
　正極は、従来から知られているリチウム二次電池に用いられている正極、すなわち、Ｌｉイオンを吸蔵放出可能な活物質を含有する正極であれば特に制限はない。例えば、活物質として、Ｌｉ１＋ｘＭＯ２（－０．１＜ｘ＜０．１、Ｍ：Ｃｏ、Ｎｉ、Ｍｎなど）で表されるリチウム含有遷移金属酸化物；ＬｉＭｎ２Ｏ４などのリチウムマンガン酸化物；ＬｉＭｎ２Ｏ４のＭｎの一部を他元素で置換したＬｉＭｎｘＭ（１－ｘ）Ｏ２；オリビン型ＬｉＭＰＯ４（Ｍ：Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ）；ＬｉＭｎ０．５Ｎｉ０．５Ｏ２；Ｌｉ（１＋ａ）ＭｎｘＮｉｙＣｏ（１－ｘ－ｙ）Ｏ２（－０．１＜ａ＜０．１、０＜ｘ＜０．５、０＜ｙ＜０．５）；などを適用することが可能である。これらの正極活物質に公知の導電助剤（カーボンブラックなどの炭素材料など）やポリフッ化ビニリデン（ＰＶＤＦ）などの結着剤などを適宜添加した正極合剤を、集電体を芯材として成形体（すなわち、正極合剤層）に仕上げたものなどを、正極として用いることができる。 The positive electrode is not particularly limited as long as it is a positive electrode used in a conventionally known lithium secondary battery, that is, a positive electrode containing an active material capable of occluding and releasing Li ions. For example, as an active material, lithium-containing transition metal oxide represented by Li 1 + x MO 2 (−0.1 <x <0.1, M: Co, Ni, Mn, etc.); lithium manganese such as LiMn 2 O 4 Oxide; LiMn x M (1-x) O 2 in which part of Mn of LiMn 2 O 4 is substituted with another element; olivine type LiMPO 4 (M: Co, Ni, Mn, Fe); LiMn 0.5 Ni 0.5 O 2 ; Li (1 + a) Mn x Ni y Co (1-xy) O 2 (−0.1 <a <0.1, 0 <x <0.5, 0 <y <0. 5); can be applied. A positive electrode mixture in which a known conductive additive (carbon material such as carbon black) or a binder such as polyvinylidene fluoride (PVDF) is appropriately added to these positive electrode active materials is molded using a current collector as a core material. What finished the body (namely, positive mix layer) etc. can be used as a positive electrode.
　正極の集電体としては、アルミニウムなどの金属の箔、パンチングメタル、網、エキスパンドメタルなどを用い得るが、通常、厚みが１０～３０μｍのアルミニウム箔が好適に用いられる。 As the positive electrode current collector, a metal foil such as aluminum, a punching metal, a net, an expanded metal, or the like can be used, but an aluminum foil having a thickness of 10 to 30 μm is usually preferably used.
　正極側のリード部は、通常、正極作製時に、集電体の一部に正極合剤層を形成せずに集電体の露出部を残し、そこをリード部とすることによって設けられる。ただし、リード部は必ずしも当初から集電体と一体化されたものであることは要求されず、集電体にアルミニウム製の箔などを後から接続することによって設けてもよい。 The lead part on the positive electrode side is usually provided by leaving the exposed part of the current collector without forming the positive electrode mixture layer on a part of the current collector and forming the lead part at the time of producing the positive electrode. However, the lead portion is not necessarily integrated with the current collector from the beginning, and may be provided by connecting an aluminum foil or the like to the current collector later.
　負極は、従来から知られているリチウム二次電池に用いられている負極、すなわち、Ｌｉイオンを吸蔵放出可能な活物質を含有する負極であれば特に制限はない。例えば、活物質として、黒鉛、熱分解炭素類、コークス類、ガラス状炭素類、有機高分子化合物の焼成体、メソカーボンマイクロビーズ（ＭＣＭＢ）、炭素繊維などの、リチウムを吸蔵、放出可能な炭素系材料の１種または２種以上の混合物が用いられる。また、Ｓｉ、Ｓｎ、Ｇｅ、Ｂｉ、Ｓｂ、Ｉｎなどの元素およびその合金、リチウム含有窒化物、またはリチウム含有酸化物などのリチウム金属に近い低電圧で充放電できる化合物、もしくはリチウム金属やリチウム／アルミニウム合金も負極活物質として用いることができる。これらの負極活物質に導電助剤（カーボンブラックなどの炭素材料など）やＰＶＤＦなどの結着剤などを適宜添加した負極合剤を、集電体を芯材として成形体（負極合剤層）に仕上げたものや、前記の各種合金やリチウム金属の箔を単独、もしくは集電体上に形成したものなどの負極剤層を有するものを、負極として用いることができる。 The negative electrode is not particularly limited as long as it is a negative electrode used in a conventionally known lithium secondary battery, that is, a negative electrode containing an active material capable of occluding and releasing Li ions. For example, carbon that can occlude and release lithium, such as graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), and carbon fibers as active materials One type or a mixture of two or more types of system materials is used. In addition, elements such as Si, Sn, Ge, Bi, Sb, In and alloys thereof, lithium-containing nitrides, compounds that can be charged and discharged at a low voltage close to lithium metal such as lithium-containing oxides, or lithium metal or lithium / An aluminum alloy can also be used as the negative electrode active material. A negative electrode mixture obtained by appropriately adding a conductive additive (carbon material such as carbon black) or a binder such as PVDF to these negative electrode active materials, and a molded body (negative electrode mixture layer) using a current collector as a core material Those having a negative electrode agent layer such as those finished in the above, or those formed from the above-mentioned various alloys and lithium metal foils alone or formed on a current collector can be used as the negative electrode.
　負極に集電体を用いる場合には、集電体としては、銅製やニッケル製の箔、パンチングメタル、網、エキスパンドメタルなどを用い得るが、通常、銅箔が用いられる。この負極集電体は、高エネルギー密度の電池を得るために負極全体の厚みを薄くする場合、厚みの上限は３０μｍであることが好ましく、また、下限は５μｍであることが望ましい。 When a current collector is used for the negative electrode, a copper or nickel foil, a punching metal, a net, an expanded metal, or the like can be used as the current collector, but a copper foil is usually used. In the negative electrode current collector, when the thickness of the entire negative electrode is reduced in order to obtain a battery having a high energy density, the upper limit of the thickness is preferably 30 μm, and the lower limit is preferably 5 μm.
　負極側のリード部も、正極側のリード部と同様に、通常、負極作製時に、集電体の一部に負極剤層（負極活物質を有する層、負極合剤層を含む）を形成せずに集電体の露出部を残し、そこをリード部とすることによって設けられる。ただし、この負極側のリード部は必ずしも当初から集電体と一体化されたものであることは要求されず、集電体に銅製の箔などを後から接続することによって設けてもよい。 As with the lead portion on the negative electrode side, the negative electrode layer (including a layer having a negative electrode active material and a negative electrode mixture layer) is usually formed on a part of the current collector during the preparation of the negative electrode. Without leaving the exposed portion of the current collector, it is provided as a lead portion. However, the lead portion on the negative electrode side is not necessarily integrated with the current collector from the beginning, and may be provided by connecting a copper foil or the like to the current collector later.
　電極は、前記の正極と前記の負極とを、本発明のセパレータを介して積層するか、または、前記の正極および負極のうちの少なくとも一方と本発明の耐熱性多孔質膜とを一体化し、この耐熱性多孔質膜が介在するようにして正極と負極とを積層した積層構造の電極群や、更にこれらを巻回した巻回構造の電極群の形態で用いることができる。なお、正極および負極のうちの少なくとも一方と本発明の耐熱性多孔質膜とを一体化したものを用いて電池を構成する場合、別途セパレータ（例えば、従来から知られているリチウム二次電池などの電池で使用されているポリオレフィン製の微多孔膜セパレータ）を使用してもよいが、本発明の耐熱性多孔質膜が正極と負極とを仕切る隔離材（すなわちセパレータ）として機能するため、特にセパレータを使用する必要はない。 The electrode is formed by laminating the positive electrode and the negative electrode via the separator of the present invention, or integrating at least one of the positive electrode and the negative electrode with the heat-resistant porous membrane of the present invention, It can be used in the form of an electrode group having a laminated structure in which a positive electrode and a negative electrode are laminated so that this heat-resistant porous film is interposed, or an electrode group having a wound structure in which these are wound. In addition, when a battery is constituted by using at least one of the positive electrode and the negative electrode integrated with the heat-resistant porous film of the present invention, a separate separator (for example, a conventionally known lithium secondary battery) The microporous membrane separator made of polyolefin used in the battery of (1) may be used, but since the heat-resistant porous membrane of the present invention functions as a separator (that is, a separator) separating the positive electrode and the negative electrode, There is no need to use a separator.
　非水電解質としては、リチウム塩を有機溶媒に溶解した溶液（非水電解液）が用いられる。リチウム塩としては、溶媒中で解離してＬｉ＋イオンを形成し、電池として使用される電圧範囲で分解などの副反応を起こさないものであれば特に制限は無い。例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＳｂＦ６などの無機リチウム塩；ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、Ｌｉ２Ｃ２Ｆ４（ＳＯ３）２、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣｎＦ２ｎ＋１ＳＯ３（２≦ｎ≦７）、ＬｉＮ（ＲｆＯＳＯ２）２〔ここでＲｆはフルオロアルキル基〕などの有機リチウム塩；などを用いることができる。 As the non-aqueous electrolyte, a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in an organic solvent is used. The lithium salt is not particularly limited as long as it dissociates in a solvent to form Li + ions and does not cause a side reaction such as decomposition in a voltage range used as a battery. For example, inorganic lithium salts such as LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 ; LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (2 ≦ n ≦ 7), LiN (R f OSO 2 ) 2 [where R f is a fluoroalkyl group]; Etc. can be used.
　非水電解液に用いる有機溶媒としては、前記のリチウム塩を溶解し、電池として使用される電圧範囲で分解などの副反応を起こさないものであれば特に限定されない。例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネートなどの環状カーボネート；ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネートなどの鎖状カーボネート；プロピオン酸メチルなどの鎖状エステル；γ－ブチロラクトンといった環状エステル；ジメトキシエタン、ジエチルエーテル、１，３－ジオキソラン、ジグライム、トリグライム、テトラグライムなどの鎖状エーテル；ジオキサン、テトラヒドロフラン、２－メチルテトラヒドロフランなどの環状エーテル；アセトニトリル、プロピオニトリル、メトキシプロピオニトリルといったニトリル類；エチレングリコールサルファイトなどの亜硫酸エステル類；などが挙げられ、これらを１種単独で用いてもよいし、２種以上を併用しても構わない。なお、より良好な特性の電池とするためには、エチレンカーボネートと鎖状カーボネートの混合溶媒など、高い導電率を得ることができる組み合わせで用いることが望ましい。また、これらの非水電解液に安全性や充放電サイクル性、高温貯蔵性といった特性を向上させる目的で、ビニレンカーボネート類、１，３－プロパンサルトン、ジフェニルジスルフィド、シクロヘキシルベンゼン、ビフェニル、フルオロベンゼン、ｔ－ブチルベンゼンなどの添加剤を適宜加えることもできる。 The organic solvent used in the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause side reactions such as decomposition in the voltage range used as a battery. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; chain esters such as methyl propionate; cyclic esters such as γ-butyrolactone; Chain ethers such as ethane, diethyl ether, 1,3-dioxolane, diglyme, triglyme and tetraglyme; cyclic ethers such as dioxane, tetrahydrofuran and 2-methyltetrahydrofuran; nitriles such as acetonitrile, propionitrile and methoxypropionitrile; Sulfites such as ethylene glycol sulfite; and the like, and these may be used alone. , It may be used in combination of two or more thereof. In order to obtain a battery with better characteristics, it is desirable to use a combination that can obtain high conductivity, such as a mixed solvent of ethylene carbonate and chain carbonate. In addition, vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexyl benzene, biphenyl, and fluorobenzene are used for the purpose of improving the safety, charge / discharge cycleability, and high-temperature storage properties of these non-aqueous electrolytes. Additives such as t-butylbenzene can also be added as appropriate.
　このリチウム塩の非水電解液中の濃度としては、０．５～１．５ｍｏｌ／ｌとすることが好ましく、０．９～１．２５ｍｏｌ／ｌとすることがより好ましい。 The concentration of this lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / l, more preferably 0.9 to 1.25 mol / l.
　また、前記の有機溶媒の代わりに、エチル－メチルイミダゾリウムトリフルオロメチルスルホニウムイミド、へプチル－トリメチルアンモニウムトリフルオロメチルスルホニウムイミド、ピリジニウムトリフルオロメチルスルホニウムイミド、グアジニウムトリフルオロメチルスルホニウムイミドといった常温溶融塩を用いることもできる。 Also, instead of the organic solvent, melting at room temperature such as ethyl-methylimidazolium trifluoromethylsulfonium imide, heptyl-trimethylammonium trifluoromethylsulfonium imide, pyridinium trifluoromethylsulfonium imide, guanidinium trifluoromethylsulfonium imide A salt can also be used.
　更に、前記の非水電解液をゲル化するような高分子材料を添加して、非水電解液をゲル状にして電池に用いてもよい。非水電解液をゲル状とするための高分子材料としては、ＰＶＤＦ、フッ化ビニリデン－ヘキサフルオロプロピレン共重合体（ＰＶＤＦ－ＨＦＰ）、ＰＡＮ、ポリエチレンオキシド、ポリプロピレンオキシド、エチレンオキシド－プロピレンオキシド共重合体、主鎖または側鎖にエチレンオキシド鎖を有する架橋ポリマー、架橋したポリ（メタ）アクリル酸エステルなど、公知のゲル状電解質形成可能なホストポリマーが挙げられる。 Furthermore, a polymer material that gels the non-aqueous electrolyte may be added, and the non-aqueous electrolyte may be gelled and used for a battery. Polymer materials for making non-aqueous electrolyte into a gel include PVDF, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), PAN, polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer And a known host polymer capable of forming a gel electrolyte, such as a crosslinked polymer having an ethylene oxide chain in the main chain or side chain, and a crosslinked poly (meth) acrylate.
　次に、上記リチウム二次電池の一例を図面に基づき説明する。図１は、本発明のリチウム二次電池の一例を示す断面図である。図１において、本発明のリチウム二次電池は、上記で説明した正極活物質を含む正極合剤層を有する正極１と、負極活物質を含む負極合剤層を有する負極２と、本発明のセパレータ３と、非水電解液４とを備えている。正極１と負極２とはセパレータ３を介して渦巻状に巻回され、巻回構造の電極群として非水電解液４と共に円筒形の電池缶５内に収容されている。 Next, an example of the lithium secondary battery will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the lithium secondary battery of the present invention. In FIG. 1, a lithium secondary battery of the present invention includes a positive electrode 1 having a positive electrode mixture layer containing the positive electrode active material described above, a negative electrode 2 having a negative electrode mixture layer containing a negative electrode active material, and A separator 3 and a non-aqueous electrolyte 4 are provided. The positive electrode 1 and the negative electrode 2 are spirally wound via a separator 3 and are housed in a cylindrical battery can 5 together with a nonaqueous electrolyte solution 4 as an electrode group having a wound structure.
　ただし、図１においては、煩雑化を避けるため、正極１や負極２の作製にあたり使用した集電体である金属箔などは図示していない。また、セパレータ３は、その切断面を示すが、断面を示すハッチングは付していない。 However, in FIG. 1, in order to avoid complication, the metal foil, which is a current collector used for manufacturing the positive electrode 1 and the negative electrode 2, is not illustrated. Moreover, although the separator 3 shows the cut surface, it does not attach | subject the hatching which shows a cross section.
　電池缶５は、例えば鉄製で表面にニッケルメッキが施されていて、その底部には上記巻回構造の電極群の挿入に先立って、例えばポリプロピレンからなる絶縁体６が配置されている。封口板７は、例えばアルミニウム製で円板状をしていて、その中央部に薄肉部７ａが設けられ、かつ薄肉部７ａの周囲に電池内圧を防爆弁９に作用させるための圧力導入口７ｂとしての孔が設けられている。そして、薄肉部７ａの上面に防爆弁９の突出部９ａが溶接され、溶接部分１１を構成している。封口板７に設けた薄肉部７ａや防爆弁９の突出部９ａなどは、図面上での理解がしやすいように、切断面のみを図示しており、切断面後方の輪郭線は図示を省略している。また、封口板７の薄肉部７ａと防爆弁９の突出部９ａとの溶接部分１１も、図面上での理解が容易なように、実際よりは誇張した状態に図示している。 The battery can 5 is made of, for example, iron and nickel-plated on the surface, and an insulator 6 made of, for example, polypropylene is disposed at the bottom of the battery can 5 prior to the insertion of the electrode group having the wound structure. The sealing plate 7 is made of, for example, aluminum and has a disk shape. A thin portion 7a is provided at the center of the sealing plate 7, and a pressure introduction port 7b for allowing the battery internal pressure to act on the explosion-proof valve 9 around the thin portion 7a. As a hole. And the protrusion part 9a of the explosion-proof valve 9 is welded to the upper surface of the thin part 7a, and the welding part 11 is comprised. The thin-walled portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are shown only on the cut surface for easy understanding on the drawing, and the contour line behind the cut surface is not shown. is doing. In addition, the welded portion 11 between the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 is also shown in an exaggerated state so as to facilitate understanding on the drawing.
　端子板８は、例えば圧延鋼製で表面にニッケルメッキが施され、周縁部が鍔状になった帽子状をしており、端子板８にはガス排出口８ａが設けられている。防爆弁９は、例えばアルミニウム製で円板状をしており、その中央部には発電要素側（図１では、下側）に先端部を有する突出部９ａが設けられ、かつ薄肉部９ｂが設けられ、突出部９ａの下面が、上記のように、封口板７の薄肉部７ａの上面に溶接され、溶接部分１１を形成している。絶縁パッキング１０は、例えばポリプロピレン製で環状をしており、封口板７の周縁部の上部に配置され、その上部に防爆弁９が配置していて、封口板７と防爆弁９とを絶縁するとともに、両者の間から電解液が漏れないように両者の間隙を封止している。環状ガスケット１２は、例えばポリプロピレンで形成されている。リード体１３は、例えばアルミニウムで形成され、封口板７と正極１とを接続している。巻回構造の電極群の上部には絶縁体１４が配置され、負極２と電池缶５の底部とは、例えばニッケル製のリード体１５で接続されている。 The terminal plate 8 is made of, for example, rolled steel, has a nickel-plated surface, has a hat-like shape with a peripheral edge portion, and the terminal plate 8 is provided with a gas discharge port 8a. The explosion-proof valve 9 is made of, for example, aluminum and has a disk shape. A projecting portion 9a having a tip portion is provided on the power generation element side (lower side in FIG. 1) at the center, and the thin-walled portion 9b As described above, the lower surface of the protruding portion 9a is welded to the upper surface of the thin-walled portion 7a of the sealing plate 7 to form the welded portion 11. The insulating packing 10 is made of, for example, polypropylene and has an annular shape. The insulating packing 10 is arranged at the upper part of the peripheral edge of the sealing plate 7, and the explosion-proof valve 9 is arranged at the upper part thereof, so that the sealing plate 7 and the explosion-proof valve 9 are insulated. At the same time, the gap between the two is sealed so that the electrolyte does not leak from between them. The annular gasket 12 is made of, for example, polypropylene. The lead body 13 is made of aluminum, for example, and connects the sealing plate 7 and the positive electrode 1. An insulator 14 is disposed on the upper part of the electrode group having a wound structure, and the negative electrode 2 and the bottom of the battery can 5 are connected by a lead body 15 made of nickel, for example.
　図１の電池においては、封口板７の薄肉部７ａと防爆弁９の突出部９ａとが溶接部分１１で接触し、防爆弁９の周縁部と端子板８の周縁部とが接触し、正極１と封口板７とは正極側のリード体１３で接続されているので、通常の状態では、正極１と端子板８とは、リード体１３、封口板７、防爆弁９およびそれらの溶接部分１１によって電気的接続が得られ、電路として正常に機能する。 In the battery of FIG. 1, the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are in contact with each other at the welded portion 11, and the peripheral portion of the explosion-proof valve 9 and the peripheral portion of the terminal plate 8 are in contact. 1 and the sealing plate 7 are connected by a lead body 13 on the positive electrode side. Therefore, in a normal state, the positive electrode 1 and the terminal plate 8 are connected to the lead body 13, the sealing plate 7, the explosion-proof valve 9 and their welded parts. The electrical connection is obtained by 11 and functions normally as an electric circuit.
　そして、電池が高温に曝されたり、過充電によって発熱するなど、電池に異常事態が起こり、電池内部にガスが発生して電池の内圧が上昇した場合には、その内圧上昇により、防爆弁９の中央部が内圧方向（図１では、上側の方向）に変形する。それに伴って溶接部分１１で一体化されてなる封口板７の薄肉部７ａに剪断力が働いて該薄肉部７ａが破断するか、または防爆弁９の突出部９ａと封口板７の薄肉部７ａとの溶接部分１１が剥離した後、この防爆弁９に設けられている薄肉部９ｂが開裂してガスを端子板８のガス排出口８ａから電池外部に排出させて電池の破裂を防止することができるように設計されている。 When an abnormal situation occurs in the battery, such as the battery is exposed to high temperature or generates heat due to overcharge, and gas is generated inside the battery and the internal pressure of the battery increases, the explosion-proof valve 9 The center part of the is deformed in the internal pressure direction (the upper direction in FIG. 1). Along with this, a shearing force is applied to the thin portion 7a of the sealing plate 7 integrated at the welded portion 11, and the thin portion 7a is broken, or the projection 9a of the explosion-proof valve 9 and the thin portion 7a of the sealing plate 7 are broken. After the welded portion 11 is peeled off, the thin-walled portion 9b provided in the explosion-proof valve 9 is cleaved to discharge the gas from the gas discharge port 8a of the terminal plate 8 to the outside of the battery, thereby preventing the battery from bursting. Designed to be able to.
　本発明の非水電池は、従来から知られているリチウム二次電池などの非水電池が用いられている各種用途と同じ用途に適用することができる。 The non-aqueous battery of the present invention can be applied to the same uses as various uses in which non-aqueous batteries such as lithium secondary batteries known in the art are used.
　以下、実施例に基づいて本発明を詳細に述べる。ただし、下記実施例は、本発明を制限するものではない。 Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.
　（実施例１）
　＜電極の作製＞
　正極は次のようにして作製した。先ず、リチウム含有複合酸化物であるＬｉＣｏＯ２（正極活物質）９０質量部に、導電助剤としてカーボンブラック５質量部を加えて混合し、この混合物に、バインダとしてＰＶＤＦ：５質量部をＮＭＰに溶解させた溶液を加え、混合して正極合剤含有スラリーとし、７０メッシュの網を通過させて粒径が大きなものを取り除いた。この正極合剤含有スラリーを、厚みが１５μｍのアルミニウム箔からなる正極集電体の両面に均一に塗付して乾燥し、その後、ロールプレス機により圧縮成形して総厚さを１０５μｍにした後、切断し、アルミニウム製のリード体を溶接して、帯状の正極を作製した。 Example 1
<Production of electrode>
The positive electrode was produced as follows. First, 90 parts by mass of LiCoO 2 (positive electrode active material), which is a lithium-containing composite oxide, is mixed with 5 parts by mass of carbon black as a conductive additive, and PVDF: 5 parts by mass as a binder is added to NMP as a binder. The dissolved solution was added and mixed to obtain a positive electrode mixture-containing slurry, which was passed through a 70-mesh net to remove large particles. After this positive electrode mixture-containing slurry is uniformly applied to both surfaces of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm and dried, and then compression molded by a roll press machine to a total thickness of 105 μm This was cut and welded with an aluminum lead body to produce a strip-like positive electrode.
　また、負極は次のようにして作製した。負極活物質として人造黒鉛を用い、バインダとしてＰＶＤＦを用い、これらを質量比９５：５の割合で混合し、更にＮＭＰを加えて混合して負極合剤含有ペーストとした。この負極合剤含有ペーストを、厚みが１０μｍの銅箔からなる負極集電体の両面に均一に塗布して乾燥し、その後、ロールプレス機により圧縮成形して総厚さを１００μｍにした後、切断し、ニッケル製のリード体を溶接して、帯状の負極を作製した。 The negative electrode was produced as follows. Artificial graphite was used as the negative electrode active material, PVDF was used as the binder, these were mixed at a mass ratio of 95: 5, and NMP was added and mixed to obtain a negative electrode mixture-containing paste. This negative electrode mixture-containing paste was uniformly applied to both sides of a negative electrode current collector made of a copper foil having a thickness of 10 μm and dried, and then compression-molded with a roll press machine to a total thickness of 100 μm. It cut | disconnected and the lead body made from nickel was welded, and the strip | belt-shaped negative electrode was produced.
　＜電解液の調製＞
　エチレンカーボネート、メチルエチルカーボネート、およびジエチルカーボネートの体積比１０：１０：３０の混合溶媒にＬｉＰＦ６を１．０ｍｏｌ／ｌの濃度で溶解させたものに、ビニレンカーボネートを、電解液の全質量に対して２．５質量％となるように添加して、電解液（非水電解質）を調製した。 <Preparation of electrolyte>
In a solvent mixture of ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate in a volume ratio of 10:10:30, LiPF 6 was dissolved at a concentration of 1.0 mol / l, and vinylene carbonate was added to the total mass of the electrolyte. The electrolyte solution (nonaqueous electrolyte) was prepared by adding 2.5% by mass.
　＜セパレータの作製＞
　耐熱温度が１５０℃以上の微粒子であるベーマイト粉末（板状、平均粒径１μｍ、アスペクト比１０、比表面積８ｍ２／ｇ）４０００ｇを、水４０００ｇに４回に分けて加え、ディスパーにより２８００ｒｐｍで５時間攪拌して均一なスラリーを調製した。この分散液に有機バインダであるポリＮ－ビニルアセトアミド（ＰＮＶＡ）の水溶液（濃度１０質量％）１２００ｇを加え、更に水を加えて均一に分散するまで室温で攪拌し、固形分比率が３０質量％のスラリー（耐熱性多孔質膜形成用スラリー）を調製した。 <Preparation of separator>
4000 g boehmite powder (plate shape, average particle diameter 1 μm, aspect ratio 10, specific surface area 8 m 2 / g) as fine particles having a heat resistance temperature of 150 ° C. or higher was added to 4000 g of water in 4 portions, and 5 times at 2800 rpm with a disper. A uniform slurry was prepared by stirring for a period of time. To this dispersion was added 1200 g of an aqueous solution (concentration: 10% by mass) of poly N-vinylacetamide (PNVA) as an organic binder, and further stirred at room temperature until water was uniformly dispersed, and the solid content ratio was 30% by mass. (Slurry for forming a heat resistant porous film) was prepared.
　片面をコロナ放電処理したＰＥ製微多孔膜（厚み１６μｍ、空孔率４０％、ＰＥの融点１３５℃）を多孔質基材として用い、その処理面上に前記のスラリーをマイクログラビアコーターによって塗布し、乾燥して耐熱性多孔質膜を形成することで、厚みが２０μｍのセパレータを得た。このセパレータの耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は７．０体積％であり、耐熱性多孔質膜の空孔率は４８％であった。 A PE microporous film (thickness 16 μm, porosity 40%, PE melting point 135 ° C.) with a corona discharge treatment on one side was used as a porous substrate, and the slurry was applied to the treated surface with a microgravure coater. The separator was dried to form a heat-resistant porous film, thereby obtaining a separator having a thickness of 20 μm. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 7.0% by volume, and the porosity of the heat resistant porous membrane was 48%.
　＜電池の組み立て＞
　前記のようにして得たセパレータを、耐熱性多孔質膜側が正極側に向くように前記正極と前記負極との間に介在させつつ重ね、渦巻状に巻回して巻回体電極群を作製した。得られた巻回体電極群を、径１８ｍｍ、高さ６５ｍｍの鉄製電池缶に入れ、電解液を注入した後に封止を行って、リチウム二次電池を作製した。なお、このリチウム二次電池は、缶の上部に、内圧が上昇した場合に圧力を逃がすための防爆弁を備えている。本実施例のリチウム二次電池では、４．２Ｖまで充電した場合（正極の電位がＬｉ基準で４．３Ｖ）の設計電気容量は、１４００ｍＡｈである。 <Battery assembly>
The separator obtained as described above was stacked while being interposed between the positive electrode and the negative electrode so that the heat-resistant porous membrane side was directed to the positive electrode side, and wound to form a wound body electrode group. . The obtained wound electrode group was put into an iron battery can having a diameter of 18 mm and a height of 65 mm, and after injecting an electrolytic solution, sealing was performed to produce a lithium secondary battery. The lithium secondary battery includes an explosion-proof valve at the top of the can for releasing the pressure when the internal pressure increases. In the lithium secondary battery of this example, the design electric capacity when charged to 4.2 V (the positive electrode potential is 4.3 V with respect to Li) is 1400 mAh.
　（実施例２）
　実施例１で用いたものと同じベーマイト粉末４０００ｇを、水４０００ｇに４回に分けて加え、ディスパーにより２８００ｒｐｍで５時間攪拌して均一な分散液を調製した。この分散液に有機バインダであるＰＮＶＡの水溶液（濃度１０質量％）４００ｇを加え、更に水を加えて均一に分散するまで室温で攪拌し、固形分比率が３０質量％のスラリーを調製した。このスラリーにフッ素系界面活性剤（パーフルオロアルキルエチレンオキシド付加物）を、水１００質量部に対して０．１質量部の量で添加し、均一になるまで攪拌して耐熱性多孔質膜形成用スラリーを得た。 (Example 2)
4000 g of the same boehmite powder used in Example 1 was added to 4000 g of water in four portions, and the mixture was stirred with a disper at 2800 rpm for 5 hours to prepare a uniform dispersion. 400 g of an aqueous solution of PNVA (concentration: 10% by mass) as an organic binder was added to this dispersion, and water was further added and stirred at room temperature until uniformly dispersed to prepare a slurry having a solid content ratio of 30% by mass. To this slurry, a fluorosurfactant (perfluoroalkylethylene oxide adduct) is added in an amount of 0.1 parts by mass with respect to 100 parts by mass of water, and stirred until uniform to form a heat resistant porous film. A slurry was obtained.
　実施例１で用いたものと同じＰＥ製微多孔膜の処理面上に、マイクログラビアコーターを用いて前記スラリーを塗布した後、乾燥して耐熱性多孔質膜を形成することで、厚みが２０μｍのセパレータを得た。このセパレータの耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は２．５体積％であり、耐熱性多孔質膜の空孔率は５２％であった。 On the treated surface of the same PE microporous membrane as used in Example 1, the slurry was applied using a micro gravure coater, and then dried to form a heat resistant porous membrane, resulting in a thickness of 20 μm. A separator was obtained. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 2.5% by volume, and the porosity of the heat resistant porous membrane was 52%.
　そして、このセパレータを用いた以外は、実施例１と同様にしてリチウム二次電池を作製した。 A lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　（実施例３）
　耐熱温度が１５０℃以上の微粒子を、一次粒子の連なった二次粒子状ベーマイト（平均粒径０．６μｍ、比表面積１５ｍ２／ｇ）に変更した以外は、実施例２と同様にして耐熱性多孔質膜形成用スラリーを作製した。ＰＥ製多孔膜を中心にして、その両側にＰＰ製多孔膜を積層した３層構造のポリオレフィン製微多孔膜（厚み１６μｍ、空孔率４０％、ＰＥ層に係るＰＥの融点１３５℃）上に、マイクログラビアコーターを用いて前記スラリーを塗布した後、乾燥して耐熱性多孔質膜を形成することで、厚みが１８μｍのセパレータを得た。このセパレータの耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は２．５体積％であり、耐熱性多孔質膜の空孔率は５５％であった。 (Example 3)
The heat resistance was the same as in Example 2 except that the fine particles having a heat resistance temperature of 150 ° C. or higher were changed to secondary particulate boehmite (average particle diameter 0.6 μm, specific surface area 15 m 2 / g) in which primary particles were continuous. A slurry for forming a porous film was prepared. A three-layer polyolefin microporous membrane (thickness 16 μm, porosity 40%, PE melting point 135 ° C. of PE layer) with a PE porous membrane as the center and a PP porous membrane laminated on both sides thereof After applying the slurry using a micro gravure coater, the slurry was dried to form a heat-resistant porous film, thereby obtaining a separator having a thickness of 18 μm. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 2.5% by volume, and the porosity of the heat resistant porous membrane was 55%.
　そして、このセパレータを用いた以外は、実施例１と同様にしてリチウム二次電池を作製した。 A lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　（実施例４）
　耐熱温度が１５０℃以上の微粒子に、実施例３で用いたものと同じ一次粒子の連なった二次粒子状ベーマイト４０００ｇを用い、これを水４０００ｇに４回に分けて加え、ディスパーにより２８００ｒｐｍで５時間攪拌して均一な分散液を調製した。この分散液に、８０～１５０℃の温度下で非水電解液を吸収して膨潤する膨潤性微粒子である架橋ＰＭＭＡ微粒子（平均粒子径０．４μｍ）の水分散体（固形分比率４０質量％）４０００ｇとＰＮＶＡの水溶液（濃度１０質量％）１６００ｇとを加え、更に水を固形分比率が３０質量％になるように加えて、均一になるまで攪拌した。このスラリーに、実施例３で用いたものと同じフッ素系界面活性剤を、水１００質量部に対して０．１質量部の量で添加し、均一になるまで攪拌して耐熱性多孔質膜形成用スラリーを得た。 Example 4
To fine particles having a heat resistant temperature of 150 ° C. or higher, 4000 g of secondary particulate boehmite with the same primary particles as used in Example 3 was added to 4000 g of water in four portions, and 5 times at 2800 rpm with a disper. A uniform dispersion was prepared by stirring for a period of time. In this dispersion, an aqueous dispersion (solid content ratio: 40% by mass) of crosslinked PMMA fine particles (average particle size 0.4 μm), which are swellable fine particles that swell by absorbing a nonaqueous electrolytic solution at a temperature of 80 to 150 ° C. ) 4000 g and 1600 g of an aqueous solution of PNVA (concentration: 10% by mass) were added, and water was further added so that the solid content ratio was 30% by mass, followed by stirring until uniform. To this slurry, the same fluorosurfactant as used in Example 3 was added in an amount of 0.1 parts by mass with respect to 100 parts by mass of water, and the mixture was stirred until uniform and heat-resistant porous membrane A forming slurry was obtained.
　実施例３で用いたものと同じ３層構造のポリオレフィン製微多孔膜上に、マイクログラビアコーターを用いて前記スラリーを塗布した後、乾燥して耐熱性多孔質膜を形成することで、厚みが２０μｍのセパレータを得た。このセパレータの耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は４．８体積％であり、耐熱性多孔質膜の空孔率は５０％であった。 On the polyolefin microporous film having the same three-layer structure as used in Example 3, the slurry was applied using a micro gravure coater and then dried to form a heat-resistant porous film. A 20 μm separator was obtained. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 4.8% by volume, and the porosity of the heat resistant porous membrane was 50%.
　そして、このセパレータを用いた以外は、実施例１と同様にしてリチウム二次電池を作製した。 A lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　（実施例５）
　耐熱温度が１５０℃以上の微粒子に、一次粒子の連なった二次粒子状ベーマイト（平均粒子径０．０６μｍ、比表面積１００ｍ２／ｇ）４０００ｇを用い、これを水４０００ｇに４回に分けて加え、ディスパーにより２８００ｒｐｍで５時間攪拌して均一な分散液を調製した。この分散液に、熱溶融性微粒子としてＰＥ微粒子（融点１３５℃）の水分散体（固形分比率４０質量％）４０００ｇとＰＮＶＡの水溶液（濃度１０質量％）２１００ｇと加え、更に水を固形分比率が３０質量％になるように加えて、均一になるまで攪拌し、耐熱性多孔質膜形成用スラリーを得た。ＰＥＴ製不織布（目付け８ｇ／ｍ２、厚み１６μｍ）を多孔質基材として用い、それに前記スラリーをディップ塗布し、乾燥して耐熱性多孔質膜を形成することで、厚みが２０μｍのセパレータを得た。このセパレータの耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は６．２体積％であり、耐熱性多孔質膜の空孔率は３８％であった。 (Example 5)
Use 4000 g of secondary particulate boehmite (average particle size 0.06 μm, specific surface area 100 m 2 / g) in which primary particles are connected to fine particles having a heat-resistant temperature of 150 ° C. or more, and add them to 4000 g of water in four portions. The mixture was stirred for 5 hours at 2800 rpm with a disper to prepare a uniform dispersion. To this dispersion, 4000 g of an aqueous dispersion (solid content ratio 40 mass%) of PE fine particles (melting point 135 ° C.) and 2100 g of an aqueous solution of PNVA (concentration 10 mass%) are added as hot-melt fine particles, and water is further added to the solid content ratio. To 30% by mass and stirred until uniform to obtain a slurry for forming a heat resistant porous film. A nonwoven fabric made of PET (weighing 8 g / m 2 , thickness 16 μm) is used as a porous substrate, and the slurry is dip coated on the porous substrate and dried to form a heat-resistant porous film, thereby obtaining a separator having a thickness of 20 μm. It was. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 6.2% by volume, and the porosity of the heat resistant porous membrane was 38%.
　そして、このセパレータを用いた以外は、実施例１と同様にしてリチウム二次電池を作製した。 A lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　（実施例６）
　耐熱温度が１５０℃以上の微粒子にアルミナ微粒子（平均粒子径０．４μｍ、比表面積７ｍ２／ｇ）４０００ｇを用い、これを水４０００ｇに４回に分けて加え、ディスパーにより２８００ｒｐｍで５時間攪拌して均一な分散液を調製した。この分散液に、熱溶融性微粒子としてＰＥ微粒子（融点１３５℃）の水分散体（固形分比率４０質量％）４０００ｇとＰＮＶＡの水溶液（濃度１０質量％）１６００ｇとを加え、更に水を固形分比率が３０質量％になるように加えて、均一になるまで攪拌し、耐熱性多孔質膜形成用スラリーを得た。 (Example 6)
4000 g of alumina fine particles (average particle size 0.4 μm, specific surface area 7 m 2 / g) are used as fine particles having a heat resistance temperature of 150 ° C. or higher, and this is added to 4000 g of water in four portions, and stirred at 2800 rpm for 5 hours with a disper. And a uniform dispersion was prepared. To this dispersion, 4000 g of an aqueous dispersion (solid content ratio: 40% by mass) of PE fine particles (melting point: 135 ° C.) and 1600 g of an aqueous solution of PNVA (concentration: 10% by mass) are added as heat-meltable fine particles. The mixture was added so that the ratio was 30% by mass, and stirred until uniform to obtain a heat-resistant porous film forming slurry.
　前記のスラリーを、実施例１で作製したものと同じ負極の両面上に、マイクログラビアコーターを用いて塗布し、厚みが２０μｍの耐熱性多孔質膜を形成した。耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は４．５体積％であり、耐熱性多孔質膜の空孔率は５０％であった。 The slurry was applied on both surfaces of the same negative electrode as that prepared in Example 1 using a micro gravure coater to form a heat-resistant porous film having a thickness of 20 μm. The volume ratio of the organic binder in the total volume of the total solid content of the heat-resistant porous film was 4.5% by volume, and the porosity of the heat-resistant porous film was 50%.
　前記の耐熱性多孔質膜と一体化した負極と、実施例１で作製したものと同じ正極とを重ね合わせ、渦巻状に巻回して巻回体電極群を作製した。この巻回体電極群を用いた以外は、実施例１と同様にしてリチウム二次電池を作製した。 The negative electrode integrated with the heat-resistant porous membrane and the same positive electrode as that prepared in Example 1 were superposed and wound in a spiral shape to produce a wound electrode group. A lithium secondary battery was produced in the same manner as in Example 1 except that this wound electrode group was used.
　（実施例７）
　実施例６で調製したものと同じ耐熱性多孔質膜形成用スラリーを、実施例１で作製したものと同じ負極の両面上に、マイクログラビアコーターを用いて塗布し、厚みが１０μｍの耐熱性多孔質膜を形成した。また、実施例６で調製したものと同じ耐熱性多孔質膜形成用スラリーを、実施例１で作製したものと同じ正極の両面上に、マイクログラビアコーターを用いて塗布し、厚みが１０μｍの耐熱性多孔質膜を形成した。 (Example 7)
The same heat-resistant porous film forming slurry as that prepared in Example 6 was applied on both surfaces of the same negative electrode as that prepared in Example 1 using a microgravure coater, and the heat-resistant porous film having a thickness of 10 μm. A membrane was formed. Further, the same heat-resistant porous film-forming slurry as that prepared in Example 6 was applied on both surfaces of the same positive electrode as that prepared in Example 1 using a microgravure coater, and the thickness was 10 μm. A porous film was formed.
　前記の耐熱性多孔質膜と一体化した負極と、前記の耐熱性多孔質膜と一体化した正極とを用いた以外は、実施例６と同様にしてリチウム二次電池を作製した。 A lithium secondary battery was produced in the same manner as in Example 6 except that the negative electrode integrated with the heat resistant porous membrane and the positive electrode integrated with the heat resistant porous membrane were used.
　（比較例１）
　有機バインダであるＰＮＶＡの水溶液（濃度１０質量％）の使用量を２０００ｇに変更した以外は、実施例１と同様にして耐熱性多孔質膜形成用スラリーを調製し、このスラリーを用いた以外は、実施例１と同様にしてセパレータを作製した。このセパレータの耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は１１体積％であり、耐熱性多孔質膜の空孔率は４２％であった。 (Comparative Example 1)
A slurry for forming a heat-resistant porous film was prepared in the same manner as in Example 1 except that the amount of the aqueous solution of PNVA (concentration: 10% by mass) used as an organic binder was changed to 2000 g, and this slurry was used except that this slurry was used. A separator was produced in the same manner as in Example 1. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 11% by volume, and the porosity of the heat resistant porous membrane was 42%.
　そして、このセパレータを用いた以外は、実施例１と同様にしてリチウム二次電池を作製した。 A lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　（比較例２）
　耐熱温度が１５０℃以上の微粒子に、ベーマイト粒子（平均粒子径０．００５μｍ、比表面積２５０ｍ２／ｇ）を用いた以外は実施例１と同様にして調製した耐熱性多孔質膜形成用スラリーを用い、実施例１と同様にしてセパレータを作製した。しかしながら、耐熱性多孔質膜のフィラーがすぐに剥がれてしまったため、電池の作製は実施しなかった。 (Comparative Example 2)
A slurry for forming a heat-resistant porous film prepared in the same manner as in Example 1 except that boehmite particles (average particle size 0.005 μm, specific surface area 250 m 2 / g) were used as fine particles having a heat-resistant temperature of 150 ° C. or higher. A separator was prepared in the same manner as in Example 1. However, since the filler of the heat resistant porous membrane was peeled off immediately, the battery was not manufactured.
　（比較例３）
　耐熱温度が１５０℃以上の微粒子に、比較例２で用いたものと同じベーマイト粒子４０００ｇを使用し、これを水４０００ｇに４回に分けて加え、ディスパーにより２８００ｒｐｍで５時間攪拌して均一な分散液を調製した。この分散液に有機バインダであるＰＮＶＡの水溶液（濃度１０質量％）４０００ｇを加え、均一に分散するまで室温で攪拌して、耐熱性多孔質膜形成用スラリーを調製した。そして、このスラリーを用いた以外は、実施例１と同様にしてセパレータを作製した。このセパレータの耐熱性多孔質膜の全固形分の全体積中における有機バインダの体積割合は２０体積％であり、耐熱性多孔質膜の空孔率は３８％であった。 (Comparative Example 3)
Use 4000 g of the same boehmite particles as those used in Comparative Example 2 for fine particles having a heat-resistant temperature of 150 ° C. or higher, add them to 4000 g of water in four portions, and stir the mixture at 2800 rpm for 5 hours with uniform dispersion. A liquid was prepared. To this dispersion, 4000 g of an aqueous solution of PNVA (concentration: 10% by mass) as an organic binder was added and stirred at room temperature until uniformly dispersed to prepare a slurry for forming a heat resistant porous film. And the separator was produced like Example 1 except having used this slurry. The volume ratio of the organic binder in the total volume of the total solid content of the heat resistant porous membrane of this separator was 20% by volume, and the porosity of the heat resistant porous membrane was 38%.
　更に、このセパレータを用いた以外は、実施例１と同様にしてリチウム二次電池を作製した。 Furthermore, a lithium secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　実施例および比較例のリチウム二次電池、並びに実施例および比較例の電池に使用したセパレータまたは耐熱性多孔質膜について、下記の各評価を行った。 The following evaluations were performed on the lithium secondary batteries of Examples and Comparative Examples, and the separators or heat-resistant porous membranes used in the batteries of Examples and Comparative Examples.
　＜セパレータまたは耐熱性多孔質膜の熱収縮試験＞
　実施例１～５および比較例１、３の電池に使用したセパレータ、並びに実施例６、７の電池に使用した耐熱性多孔質膜と負極との一体化物から、ＭＤ方向、ＴＤ方向をそれぞれ５ｃｍ、１０ｃｍとした短冊状のサンプル片を切り取った。ここで、ＭＤ方向とは、セパレータまたは耐熱性多孔質膜と負極との一体化物の作製の際の機械方向であり、ＴＤ方向はそれらに垂直な方向である。 <Heat shrinkage test of separator or heat-resistant porous membrane>
From the separator used in the batteries of Examples 1 to 5 and Comparative Examples 1 and 3, and the integrated body of the heat-resistant porous membrane and the negative electrode used in the batteries of Examples 6 and 7, the MD direction and the TD direction are each 5 cm. A strip-shaped sample piece of 10 cm was cut out. Here, the MD direction is the machine direction when producing an integrated product of the separator or heat-resistant porous membrane and the negative electrode, and the TD direction is a direction perpendicular to them.
　前記の各サンプルについて、長辺方向（ＴＤ方向）の中心と短片方向（ＭＤ方向）の中心とで交差するように、長辺方向および短辺方向に平行にそれぞれ３ｃｍずつの直線を油性ペンでマークした。なお、それぞれの直線の中心は、これらの直線の交差点とした。これらのサンプルを恒温槽に吊るし、槽内温度を５℃／分の割合で温度上昇させ、１５０℃に到達後、１５０℃で１時間温度を保持した。１５０℃で１時間保持した後の長辺方向および短辺方向のマークの長さを測定し、昇温前のそれぞれのマークの長さと昇温後のそれぞれのマークの長さとの差を求め、昇温前のそれぞれのマークの長さに対するこれらの差の比を百分率で算出して、それぞれの方向の熱収縮率とした。なお、各セパレータおよび耐熱性多孔質膜の熱収縮率は、長辺方向の熱収縮率と短辺方向の熱収縮率のうちの値の大きい方とした。 For each of the above samples, straight lines of 3 cm each in parallel with the long side direction and the short side direction are crossed with the oil pen so that the center in the long side direction (TD direction) and the center in the short piece direction (MD direction) intersect each other. Marked. The center of each straight line was the intersection of these straight lines. These samples were suspended in a thermostat, the temperature inside the bath was increased at a rate of 5 ° C./min, and after reaching 150 ° C., the temperature was held at 150 ° C. for 1 hour. Measure the length of the mark in the long side direction and the short side direction after holding at 150 ° C. for 1 hour, and determine the difference between the length of each mark before the temperature rise and the length of each mark after the temperature rise, The ratio of these differences with respect to the length of each mark before the temperature increase was calculated as a percentage to obtain the heat shrinkage rate in each direction. In addition, the heat shrinkage rate of each separator and the heat resistant porous film was set to the larger one of the heat shrinkage rate in the long side direction and the heat shrinkage rate in the short side direction.
　＜充放電特性評価＞
　実施例１～７および比較例１、３の各電池について、以下の条件で充放電を行い、充電容量および放電容量をそれぞれ求め、充電容量に対する放電容量の割合を充電効率として評価した。充電は、０．２Ｃの電流値で電池電圧が４．２Ｖになるまで定電流充電を行い、次いで、４．２Ｖでの定電圧充電を行う定電流－定電圧充電とした。充電終了までの総充電時間は１５時間とした。充電後の各電池を、０．２Ｃの放電電流で、電池電圧が３．０Ｖになるまで放電を行ったところ、実施例１～７および比較例１、３の電池は、充電効率がほぼ１００％となり、電池として良好に作動することが確認できた。 <Charge / discharge characteristics evaluation>
The batteries of Examples 1 to 7 and Comparative Examples 1 and 3 were charged and discharged under the following conditions to determine the charge capacity and the discharge capacity, respectively, and the ratio of the discharge capacity to the charge capacity was evaluated as the charge efficiency. The charging was constant current-constant voltage charging in which constant current charging was performed until the battery voltage reached 4.2 V at a current value of 0.2 C, and then constant voltage charging at 4.2 V was performed. The total charging time until the end of charging was 15 hours. When each battery after charging was discharged at a discharge current of 0.2 C until the battery voltage reached 3.0 V, the batteries of Examples 1 to 7 and Comparative Examples 1 and 3 had a charging efficiency of approximately 100. %, Confirming that the battery operates well.
　＜出力特性評価＞
　実施例１～７および比較例１、３の各電池について、充放電特性評価と同じ条件で充電し、１Ｃの放電電流で電池電圧が３．０Ｖになるまで放電したときの放電容量と、同条件で充電し、１０Ｃの放電電流で電池電圧が３．０Ｖになるまで放電したときの放電容量とを測定し、１Ｃでの放電容量に対する１０Ｃでの放電容量の比（１０Ｃ／１Ｃ容量比）を百分率で表して、各電池の出力特性を評価した。 <Output characteristics evaluation>
For each of the batteries of Examples 1 to 7 and Comparative Examples 1 and 3, the charge capacity was the same as the charge capacity when charged under the same conditions as the charge / discharge characteristic evaluation and discharged until the battery voltage reached 3.0V with a discharge current of 1C. The discharge capacity is measured when the battery is charged under the conditions and discharged until the battery voltage reaches 3.0 V with a discharge current of 10 C, and the ratio of the discharge capacity at 10 C to the discharge capacity at 1 C (10C / 1C capacity ratio) As a percentage, the output characteristics of each battery were evaluated.
　＜安全性評価＞
　以下の方法により、実施例１～７および比較例１、３の各電池の昇温試験を行った。電池を恒温槽に入れ、３０℃から１５０℃まで毎分１℃の割合で温度上昇させて過熱し、電池の表面温度の変化を求めた。その結果、全ての電池で異常な温度上昇は確認されず、安全性が優れていることが確認できた。 <Safety evaluation>
The temperature increase test of each battery of Examples 1 to 7 and Comparative Examples 1 and 3 was performed by the following method. The battery was placed in a thermostatic bath and heated at a rate of 1 ° C./min from 30 ° C. to 150 ° C. for overheating to determine the change in the surface temperature of the battery. As a result, no abnormal temperature rise was confirmed in all the batteries, and it was confirmed that the safety was excellent.
　安全性評価を除く前記の各評価結果を表１に示す。 Table 1 shows the results of the above evaluations excluding safety evaluation.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表１に示す通り、有機バインダの体積割合が適正な耐熱性多孔質膜を有する実施例１～７のリチウム二次電池は、出力特性が良好である。また、実施例１～５のリチウム二次電池で使用したセパレータおよび実施例６、７のリチウム二次電池で使用した耐熱性多孔質膜は、１５０℃での熱収縮率が小さいことから、これらを使用した実施例１～７のリチウム二次電池は、電池内が高温となっても、セパレータや隔離材（電極と一体化された耐熱性多孔質膜）の熱収縮による短絡の発生を抑制することができ、前記の安全性評価で示した通り、良好な安全性を有している。 As shown in Table 1, the lithium secondary batteries of Examples 1 to 7 having a heat-resistant porous film with an appropriate organic binder volume ratio have good output characteristics. The separators used in the lithium secondary batteries of Examples 1 to 5 and the heat-resistant porous membrane used in the lithium secondary batteries of Examples 6 and 7 have a low thermal shrinkage at 150 ° C. The lithium secondary batteries of Examples 1 to 7 that use Pt suppress the occurrence of short circuits due to thermal contraction of separators and separators (heat-resistant porous membrane integrated with electrodes) even when the temperature inside the batteries becomes high. As shown in the safety evaluation, it has good safety.
　これに対し、有機バインダの体積割合が大きすぎる耐熱性多孔質膜を有する比較例１、３のリチウム二次電池は、出力特性が実施例の電池よりも劣っている。 In contrast, the lithium secondary batteries of Comparative Examples 1 and 3 having a heat-resistant porous film in which the volume ratio of the organic binder is too large are inferior in output characteristics to the batteries of the examples.
　本発明は、その趣旨を逸脱しない範囲で、上記以外の形態としても実施が可能である。本出願に開示された実施形態は一例であって、これらに限定はされない。本発明の範囲は、上述の明細書の記載よりも、添付されている請求の範囲の記載を優先して解釈され、請求の範囲と均等の範囲内での全ての変更は、請求の範囲に含まれるものである。 The present invention can be implemented in forms other than those described above without departing from the spirit of the present invention. The embodiments disclosed in the present application are merely examples, and the present invention is not limited thereto. The scope of the present invention is construed in preference to the description of the appended claims rather than the description of the above specification, and all modifications within the scope equivalent to the claims are construed in the scope of the claims. It is included.
　１　正極
　２　負極
　３　セパレータ
　４　非水電解液
　５　電池缶
　６　絶縁体
　７　封口板
　７ａ　薄肉部
　７ｂ　圧力導入口
　８　端子板
　８ａ　ガス排出口
　９　防爆弁
　９ａ　突出部
　９ｂ　薄肉部
１０　絶縁パッキング
１１　溶接部分
１２　環状ガスケット
１３　リード体
１４　絶縁体
１５　リード体 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Non-aqueous electrolyte 5 Battery can 6 Insulator 7 Sealing board 7a Thin part 7b Pressure inlet 8 Terminal board 8a Gas exhaust 9 Explosion-proof valve 9a Protrusion part 9b Thin part 10 Insulation packing 11 Weld part 12 Annular gasket 13 Lead body 14 Insulator 15 Lead body

Claims (20)

  1. 　多孔質基材と、耐熱性多孔質膜とが、一体化している非水電池用セパレータであって、
    　前記耐熱性多孔質膜は、耐熱温度が１５０℃以上の微粒子と、有機バインダとを含み、
    　前記微粒子の平均粒子径が、０．０１～１０μｍであり、
    　前記耐熱性多孔質膜の全固形分中に占める前記有機バインダの割合が、７体積％以下であることを特徴とする非水電池用セパレータ。     The porous substrate and the heat-resistant porous membrane are integrated non-aqueous battery separators,
    The heat-resistant porous membrane includes fine particles having a heat-resistant temperature of 150 ° C. or higher, and an organic binder,
    The fine particles have an average particle diameter of 0.01 to 10 μm,
    The nonaqueous battery separator, wherein a ratio of the organic binder in the total solid content of the heat resistant porous membrane is 7% by volume or less.
  2. 　前記多孔質基材が、ポリオレフィン製微多孔膜である請求項１に記載の非水電池用セパレータ。 The separator for a non-aqueous battery according to claim 1, wherein the porous substrate is a polyolefin microporous membrane.
  3. 　１５０℃における熱収縮率が、５％以下である請求項１に記載の非水電池用セパレータ。 The non-aqueous battery separator according to claim 1, wherein the thermal shrinkage at 150 ° C is 5% or less.
  4. 　前記微粒子が、無機酸化物微粒子である請求項１に記載の非水電池用セパレータ。 The separator for a non-aqueous battery according to claim 1, wherein the fine particles are inorganic oxide fine particles.
  5. 　前記耐熱性多孔質膜は、８０～１５０℃で溶融する微粒子を更に含む請求項１に記載の非水電池用セパレータ。 The non-aqueous battery separator according to claim 1, wherein the heat-resistant porous membrane further contains fine particles that melt at 80 to 150 ° C.
  6. 　前記耐熱性多孔質膜は、８０～１５０℃の温度下で非水電解液を吸収して膨潤する微粒子を更に含む請求項１に記載の非水電池用セパレータ。 The separator for a non-aqueous battery according to claim 1, wherein the heat-resistant porous membrane further contains fine particles that swell by absorbing the non-aqueous electrolyte at a temperature of 80 to 150 ° C.
  7. 　前記有機バインダは、分子内にアミド結合を有する請求項１に記載の非水電池用セパレータ。 The non-aqueous battery separator according to claim 1, wherein the organic binder has an amide bond in the molecule.
  8. 　前記有機バインダは、下記一般式（１）で表されるモノマー由来の構造単位を含む請求項７に記載の非水電池用セパレータ。
    Figure JPOXMLDOC01-appb-C000001
     　前記一般式（１）中、Ｒ１は水素またはメチル基、Ｒ２およびＲ３は、Ｒ２が水素もしくは炭素数１～６のアルキル基およびＲ３が水素もしくは炭素数１～４のアルキル基であるか、またはＲ２とＲ３とが互いに結合して環を形成しており、前記環のＲ２およびＲ３における炭素数の合計が２～１０である。     The separator for a nonaqueous battery according to claim 7, wherein the organic binder includes a structural unit derived from a monomer represented by the following general formula (1).
    Figure JPOXMLDOC01-appb-C000001
     In the general formula (1), R 1 is hydrogen or a methyl group, R 2 and R 3 are R 2 is hydrogen or an alkyl group having 1 to 6 carbon atoms, and R 3 is hydrogen or an alkyl group having 1 to 4 carbon atoms. Or R 2 and R 3 are bonded to each other to form a ring, and the total number of carbon atoms in R 2 and R 3 of the ring is 2 to 10.
  9. 　正極、負極、耐熱性多孔質膜および非水電解質を含む非水電池であって、
    　前記耐熱性多孔質膜と、前記正極および前記負極から選ばれる少なくとも一方とが、一体化しており、
    　前記耐熱性多孔質膜は、耐熱温度が１５０℃以上の微粒子と、有機バインダとを含み、
    　前記微粒子の平均粒子径が、０．０１～１０μｍであり、
    　前記耐熱性多孔質膜の全固形分中に占める前記有機バインダの割合が、７体積％以下であることを特徴とする非水電池。     A non-aqueous battery comprising a positive electrode, a negative electrode, a heat-resistant porous membrane and a non-aqueous electrolyte,
    The heat-resistant porous membrane and at least one selected from the positive electrode and the negative electrode are integrated,
    The heat-resistant porous membrane includes fine particles having a heat-resistant temperature of 150 ° C. or higher, and an organic binder,
    The fine particles have an average particle diameter of 0.01 to 10 μm,
    The nonaqueous battery, wherein a ratio of the organic binder in the total solid content of the heat resistant porous membrane is 7% by volume or less.
  10. 　前記微粒子が、無機酸化物微粒子である請求項９に記載の非水電池。 The nonaqueous battery according to claim 9, wherein the fine particles are inorganic oxide fine particles.
  11. 　前記耐熱性多孔質膜は、８０～１５０℃で溶融する微粒子を更に含む請求項９に記載の非水電池。 The non-aqueous battery according to claim 9, wherein the heat-resistant porous membrane further contains fine particles that melt at 80 to 150 ° C.
  12. 　前記耐熱性多孔質膜は、８０～１５０℃の温度下で非水電解液を吸収して膨潤する微粒子を更に含む請求項９に記載の非水電池。 The non-aqueous battery according to claim 9, wherein the heat-resistant porous membrane further includes fine particles that swell by absorbing the non-aqueous electrolyte at a temperature of 80 to 150 ° C.
  13. 　前記有機バインダは、分子内にアミド結合を有する請求項９に記載の非水電池。 The non-aqueous battery according to claim 9, wherein the organic binder has an amide bond in the molecule.
  14. 　正極、負極、セパレータおよび非水電解質を含む非水電池であって、
    　前記セパレータが、多孔質基材と、耐熱性多孔質膜とが、一体化しており、
    　前記耐熱性多孔質膜は、耐熱温度が１５０℃以上の微粒子と、有機バインダとを含み、
    　前記微粒子の平均粒子径が、０．０１～１０μｍであり、
    　前記耐熱性多孔質膜の全固形分中に占める前記有機バインダの割合が、７体積％以下であることを特徴とする非水電池。     A non-aqueous battery comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte,
    In the separator, the porous substrate and the heat-resistant porous membrane are integrated,
    The heat-resistant porous membrane includes fine particles having a heat-resistant temperature of 150 ° C. or higher, and an organic binder,
    The fine particles have an average particle diameter of 0.01 to 10 μm,
    The nonaqueous battery, wherein a ratio of the organic binder in the total solid content of the heat resistant porous membrane is 7% by volume or less.
  15. 　前記多孔質基材が、ポリオレフィン製微多孔膜である請求項１４に記載の非水電池。 The nonaqueous battery according to claim 14, wherein the porous substrate is a polyolefin microporous membrane.
  16. 　前記セパレータの１５０℃における熱収縮率が、５％以下である請求項１４に記載の非水電池。 The non-aqueous battery according to claim 14, wherein the separator has a heat shrinkage rate at 150 ° C. of 5% or less.
  17. 　前記微粒子が、無機酸化物微粒子である請求項１４に記載の非水電池。 The nonaqueous battery according to claim 14, wherein the fine particles are inorganic oxide fine particles.
  18. 　前記耐熱性多孔質膜は、８０～１５０℃で溶融する微粒子を更に含む請求項１４に記載の非水電池。 The non-aqueous battery according to claim 14, wherein the heat-resistant porous membrane further contains fine particles that melt at 80 to 150 ° C.
  19. 　前記耐熱性多孔質膜は、８０～１５０℃の温度下で非水電解液を吸収して膨潤する微粒子を更に含む請求項１４に記載の非水電池。 The non-aqueous battery according to claim 14, wherein the heat-resistant porous membrane further includes fine particles that swell by absorbing the non-aqueous electrolyte at a temperature of 80 to 150 ° C.
  20. 　前記有機バインダは、分子内にアミド結合を有する請求項１４に記載の非水電池。
          The non-aqueous battery according to claim 14, wherein the organic binder has an amide bond in the molecule.
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CN114665227B (en) * 2022-03-23 2024-04-09 哈尔滨工业大学无锡新材料研究院 High-wettability lithium ion battery diaphragm and preparation method thereof

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