WO2012053286A1 - Separator for electrochemical element, method for manufacturing same, electrode for electrochemical element, electrochemical element - Google Patents

Separator for electrochemical element, method for manufacturing same, electrode for electrochemical element, electrochemical element Download PDF

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Publication number
WO2012053286A1
WO2012053286A1 PCT/JP2011/070050 JP2011070050W WO2012053286A1 WO 2012053286 A1 WO2012053286 A1 WO 2012053286A1 JP 2011070050 W JP2011070050 W JP 2011070050W WO 2012053286 A1 WO2012053286 A1 WO 2012053286A1
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Prior art keywords
separator
resin
electrochemical element
volume
electrochemical
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PCT/JP2011/070050
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French (fr)
Japanese (ja)
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中村祐介
児島映理
片山秀昭
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日立マクセルエナジー株式会社
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Priority to CN2011800505053A priority Critical patent/CN103229330A/en
Priority to JP2012539635A priority patent/JPWO2012053286A1/en
Publication of WO2012053286A1 publication Critical patent/WO2012053286A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/42—Acrylic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to an electrochemical element separator excellent in dimensional stability at high temperature and short circuit resistance during bending, a method for producing the same, an electrode for electrochemical element integrated with the separator, and the separator for electrochemical element
  • the present invention relates to an electrochemical element that is safe even in a high temperature environment.
  • Electrochemical elements using non-aqueous electrolytes such as lithium secondary batteries and non-aqueous electrolytes typified by supercapacitors are characterized by high energy density, and are used in mobile devices such as mobile phones and notebook personal computers. It is widely used as a power source, and there is a tendency that the capacity of the electrochemical device is further increased along with the improvement of the performance of the portable device, and ensuring further safety is an important issue.
  • a polyolefin-based porous film having a thickness of about 20 to 30 ⁇ m is used as a separator interposed between a positive electrode and a negative electrode.
  • a complicated process such as biaxial stretching or extraction of a pore opening agent is used in order to open fine and uniform holes, and the cost is high.
  • separators are expensive.
  • 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.
  • polyethylene having a melting point of about 120 to 140 ° C. is used.
  • meltdown in which the melted polyethylene easily flows and the separator breaks may occur. In such a case, there is a risk that the positive and negative electrodes are in direct contact and the temperature further increases.
  • Patent Document 1 discloses a separator using a wholly aromatic polyamide microporous film
  • Patent Document 2 discloses a separator using a polyimide porous film
  • Patent Document 3 discloses a technique related to a separator using a polyamide nonwoven fabric
  • Patent Document 4 discloses a technique related to a separator based on a nonwoven fabric using aramid fibers.
  • a heat-resistant microporous membrane or nonwoven fabric is used, the cost of the material or difficulty in manufacturing becomes a problem.
  • Patent Document 5 discloses a technique relating to a separator having a porous inorganic coating on and in a polymer nonwoven fabric substrate. Since such a separator employs an inorganic coating that is excellent in heat resistance but lacks flexibility, when applied to an electrochemical element using a wound body, there is a risk that a crack will occur due to bending and a short circuit may occur. . In particular, in an electrochemical element using a flat wound body such as a square battery, intense bending occurs, and thus such a separator is very difficult to apply.
  • the present invention has been made in view of the above circumstances, and provides an electrochemical element excellent in reliability and safety at high temperatures, a separator that can constitute the electrochemical element, and a method for manufacturing the same.
  • the separator for an electrochemical element of the present invention is a separator for an electrochemical element that is formed by photopolymerization and includes a resin A having a cross-linked structure and electrically insulating inorganic fine particles B, except for the pore volume,
  • the ratio a / b between the volume a of the resin A and the volume b of the inorganic fine particles B is 0.6 to 9.
  • the method for producing an electrochemical element separator of the present invention is the method for producing an electrochemical element separator of the present invention, wherein the volatile material is formed from a sheet for forming an electrochemical element separator containing a volatile substance.
  • the electrochemical element electrode of the present invention is characterized by being integrated with the electrochemical element separator of the present invention.
  • the electrochemical element of the present invention is an electrochemical element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the separator is the separator for an electrochemical element of the present invention.
  • the reliability of the electrochemical device and the safety at high temperatures can be improved.
  • FIG. 1A is a plan view showing an example of an electrochemical element (non-aqueous electrolyte secondary battery) of the present invention
  • FIG. 1B is a cross-sectional view of FIG. 1A
  • FIG. 2 is a perspective view showing an example of the electrochemical element of the present invention.
  • the separator for an electrochemical element of the present invention (hereinafter simply referred to as “separator”) is used for a separator of an electrochemical element having a non-aqueous electrolyte, and is formed by photopolymerization and has a crosslinked structure at least partially.
  • the ratio a / b of the volume of the resin A to a (volume excluding the void volume) and the volume of the inorganic fine particles B to b (volume excluding the void volume) is 0. .6 or more and 9 or less.
  • the separator of the present invention by optimizing the composition ratio of the resin A and the inorganic fine particles B, the flexibility of the separator, the mechanical strength and the heat shrinkability can be ensured satisfactorily. It is supposed that an electrochemical element excellent in safety at a high temperature can be constituted.
  • a wound electrode group especially a prismatic battery
  • a separator with excellent short-circuit resistance that can suppress the occurrence of defects such as cracks even when it is bent as in the case of a flat wound body electrode group) It is said.
  • the separator of the present invention uses a resin having a high flexibility, even a separator formed by coating on an electrode is not contracted by the separator, and further, a roll-to-roll separator. In the manufacturing process, there are no defects such as cracks, and the productivity is excellent.
  • the separator of the present invention by setting the a / b value to 9 or less, preferably 8 or less, the function of the inorganic fine particles B can be effectively extracted, and the dimensional stability at high temperature is improved.
  • the separator is excellent in heat-shrinkage resistance and has excellent short-circuit resistance by ensuring high strength (mechanical strength) and the like.
  • the electrochemical element of the present invention constituted by using the separator of the present invention having these functions has good reliability and safety at high temperatures.
  • the volume a of the resin A is a value calculated from the density of the resin A and the mass of the resin A in the separator
  • the volume b of the inorganic fine particles B is the density of the inorganic fine particles B and the separator. It is a value calculated from the mass of the inorganic fine particles B.
  • the resin A according to the separator of the present invention is formed by photopolymerization. With such a resin A, the separator can be manufactured easily and the manufacturing time can be shortened, so that the productivity of the separator can be increased.
  • resin A has a melting temperature and a glass transition temperature measured using a differential scanning calorimeter (DSC) in accordance with the provisions of Japanese Industrial Standard (JIS) K 7121.
  • DSC differential scanning calorimeter
  • the glass transition temperature of the resin A is preferably 0 ° C. or lower, and more preferably ⁇ 10 ° C. or lower.
  • the melting temperature of the resin A is preferably 80 ° C. or higher, and more preferably 100 ° C. or higher.
  • Such resin A examples include those formed by photopolymerization of known monomers and oligomers. Specifically, for example, an acrylic resin formed from an acrylic resin monomer [alkyl (meth) acrylate such as methyl methacrylate and methyl acrylate and derivatives thereof] and oligomers thereof and a crosslinking agent; urethane acrylate and a crosslinking agent And a crosslinked resin formed from an epoxy acrylate and a crosslinking agent.
  • the crosslinking agent includes dioxane glycol diacrylate, tricyclodecane dimethanol diacrylate, ethylene oxide modified trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, caprolactone modified dipentaerythritol hexaacrylate.
  • Divalent or polyvalent acrylic monomers such as ⁇ -caprolactone-modified dipentaerythritol hexaacrylate can be used.
  • the resin A includes a crosslinked resin derived from an unsaturated polyester resin formed by photopolymerization from a mixture of an ester composition prepared by condensation polymerization of a divalent or polyvalent alcohol and a dicarboxylic acid and a styrene monomer; Resins formed by photopolymerization from polyfunctional epoxy, polyfunctional oxetane or a mixture thereof; various polyurethane resins produced by photopolymerization reaction of polyisocyanate and polyol; and the like can also be used.
  • polyfunctional epoxy examples include ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerol polyglycidyl ether, sorbitol glycidyl ether, and 3,4-epoxycyclohexane.
  • examples include hexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate and 1,2: 8,9 diepoxy limonene.
  • polyfunctional oxetane examples include 3-ethyl-3 ⁇ [(3-ethyloxetane-3-yl) methoxy] methyl ⁇ oxetane and xylene bisoxetane.
  • examples of the polyisocyanate include hexamethylene diisocyanate, phenylene diisocyanate, toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) or bis- (4-isocyanatocyclohexyl). Examples include methane.
  • polyether polyol, polycarbonate polyol, polyester polyol etc. are mentioned, for example.
  • a monofunctional monomer such as isobornyl acrylate, methoxy polyethylene glycol acrylate, or phenoxy polyethylene glycol acrylate can be used in combination.
  • a resin A having a better balance between flexibility and strength can be formed.
  • the inorganic fine particles B according to the separator of the present invention are components that contribute to improvement of short circuit resistance by increasing the strength and dimensional stability of the separator. Further, the inorganic fine particles B can easily control the porosity and the pore diameter of the separator.
  • the inorganic fine particles B have electrical insulating properties and heat resistance that does not react and deform at temperatures of 150 ° C. or higher, and are used in the production of non-aqueous electrolytes and separators in electrochemical devices (described later). As long as it is electrochemically stable and resistant to oxidation and reduction within the operating voltage range of the electrochemical element, there is no particular limitation.
  • the inorganic fine particles B include inorganic oxide fine particles such as iron oxide, silica (SiO 2 ), alumina (Al 2 O 3 ), TiO 2 (titania), BaTiO 3 ; inorganic nitride such as aluminum nitride and silicon nitride.
  • inorganic oxide fine particles such as calcium fluoride, barium fluoride, barium sulfate, and the like; insoluble crystal particles such as silicon and diamond; clay particles such as montmorillonite;
  • the inorganic oxide fine particles may be fine particles such as boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, or a mineral resource-derived material or an artificial product thereof.
  • the surface of a conductive material exemplified by a metal, SnO 2 , a conductive oxide such as tin-indium oxide (ITO) or a carbonaceous material such as carbon black or graphite, and the like has an electrically insulating material (
  • covering with the said inorganic oxide etc. may be sufficient.
  • the inorganic fine particles B those exemplified above may be used alone or in combination of two or more.
  • inorganic oxide fine particles are more preferable, and alumina, titania, silica, and boehmite are more preferable.
  • the average particle diameter of the inorganic fine particles B is preferably 0.001 ⁇ m or more, more preferably 0.1 ⁇ m or more, and preferably 15 ⁇ m or less, and preferably 1 ⁇ m or less. More preferred.
  • the average particle size of the inorganic fine particles B is, for example, the number average particle size measured by dispersing the inorganic fine particles B in a medium that does not dissolve using a laser scattering particle size distribution analyzer (for example, “LA-920” manufactured by HORIBA). Can be defined as
  • the inorganic fine particle B may have a shape close to a sphere, and may have a plate shape or a fiber shape, but from the viewpoint of improving the short circuit resistance of the separator.
  • it is preferably a plate-like particle or a particle having a secondary particle structure in which primary particles are aggregated.
  • particles having a secondary particle structure in which primary particles are aggregated are more preferable.
  • the plate-like particles and secondary particles include plate-like alumina, plate-like boehmite, secondary particle-like alumina, and secondary particle-like boehmite.
  • the resin A and the inorganic fine particles B do not use a porous substrate made of a fibrous material to be described later, it is preferable that these are the main components of the separator.
  • the total volume of A and the inorganic fine particles B is preferably 50% by volume or more, and more preferably 70% by volume or more, in the total volume of components constituting the separator (volume excluding the void portion). 100 volume% may be sufficient.
  • the total volume of the resin A and the inorganic fine particles B is the total volume of components constituting the separator (hole portion)
  • the volume is preferably 20% by volume or more, and more preferably 40% by volume or more.
  • a fibrous material may be mixed together with the resin A and the inorganic fine particles B.
  • the fibrous material has a heat-resistant temperature (temperature at which no deformation is observed during visual observation) of 150 ° C. or more, has an electrical insulating property, is electrochemically stable, and has an electrochemical element.
  • the material is not particularly limited as long as it is stable to the solvent used in the production of the non-aqueous electrolyte and the separator.
  • the “fibrous material” in the present invention means an aspect ratio [length in the long direction / width in the direction perpendicular to the long direction (diameter)] of 4 or more, and the aspect ratio Is preferably 10 or more.
  • constituent material of the fibrous material include, for example, cellulose and its modified products (carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), etc.), polyolefin (polypropylene (PP), propylene copolymer, etc.), Polyester (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), etc.), polyacrylonitrile (PAN), aramid, polyamideimide, polyimide and other resins; glass, alumina, zirconia, silica and other inorganic materials These constituent materials may contain 2 or more types.
  • the fibrous material may contain various known additives (for example, an antioxidant in the case of a resin) as necessary.
  • the diameter of the fibrous material may be equal to or less than the thickness of the separator, but is preferably 0.01 to 5 ⁇ m, for example.
  • the diameter is too large, the entanglement between the fibrous materials is insufficient, and when the base material of the separator is formed by forming a sheet-like material, the strength may be reduced and handling may be difficult.
  • the diameter is too small, the pores of the separator become too small, and the ion permeability tends to decrease, which may reduce the load characteristics of the electrochemical element.
  • the content of the fibrous material in the separator is, for example, preferably 10% by volume or more, and more preferably 20% by volume or more, among all the constituent components.
  • the content of the fibrous material in the separator is preferably 70% by volume or less, and preferably 60% by volume or less, but when used as a porous substrate described later, 90% by volume or less. It is preferable that it is 80 volume% or less.
  • the state of the presence of the fibrous material in the separator is, for example, that the angle of the long axis (long axis) with respect to the separator surface is preferably 30 ° or less on average, and more preferably 20 ° or less. .
  • the separator of the present invention preferably has a shutdown function from the viewpoint of further enhancing the safety of the electrochemical element used.
  • a thermoplastic resin having a melting point of 80 ° C. or higher and 140 ° C. or lower (hereinafter referred to as “hot-meltable resin C”) is contained, or liquid non-aqueous by heating.
  • a resin hereinafter referred to as “thermally swellable resin D”) that absorbs an electrolyte (non-aqueous electrolyte; hereinafter sometimes abbreviated as “electrolyte”) and swells and increases in degree of swelling as the temperature rises. It can be included.
  • the hot-melt resin C melts and closes the pores of the separator, or the heat-swellable resin D is inside the electrochemical element.
  • the non-aqueous electrolyte is absorbed to cause a shutdown that suppresses the progress of the electrochemical reaction.
  • the heat-meltable resin C is a resin having a melting point, that is, a melting temperature measured using DSC of 80 ° C. or higher and 140 ° C. or lower in accordance with JIS K 7121, and a melting temperature of 120 ° C. or higher. More preferably, it has electrical insulation properties, is stable to the non-aqueous electrolyte of the electrochemical element and the solvent used in the production of the separator, and is oxidized and reduced within the operating voltage range of the electrochemical element. A difficult electrochemically stable material is preferred.
  • polyethylene polyethylene
  • PP polypropylene
  • copolymerized polyolefin polyolefin derivatives (such as chlorinated polyethylene)
  • polyolefin wax petroleum wax
  • carnauba wax examples include polyethylene (PE), polypropylene (PP), copolymerized polyolefin, polyolefin derivatives (such as chlorinated polyethylene), polyolefin wax, petroleum wax, and carnauba wax.
  • the copolymer polyolefin include an ethylene-vinyl monomer copolymer, more specifically, an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer, and ethylene-ethyl.
  • EVA ethylene-vinyl acetate copolymer
  • An ethylene-acrylic acid copolymer such as an acrylate copolymer can be exemplified.
  • the structural unit derived from ethylene in the copolymerized polyolefin is desirably 85 mol% or more. Moreover, polycycloolefin etc. can also be used.
  • the heat-meltable resin C the above exemplified resins may be used alone or in combination of two or more.
  • the heat-meltable resin C among the materials exemplified above, PE, polyolefin wax, PP, or EVA having a structural unit derived from ethylene of 85 mol% or more is suitably used. Moreover, the heat-meltable resin C may contain various known additives (for example, antioxidants) added to the resin as necessary.
  • the heat-swellable resin D in the temperature range (approximately 70 ° C. or lower) in which the battery is normally used, the electrolytic solution is not absorbed or the amount of absorption is limited, and thus the degree of swelling is below a certain level.
  • Tc required temperature
  • a resin having such a property that it absorbs the electrolyte and swells greatly and the degree of swelling increases as the temperature rises is used.
  • a flowable electrolyte solution that is not absorbed by the heat-swellable resin D exists in the pores of the separator at a temperature lower than Tc.
  • thermal swelling there is a case where the degree of swelling increases with increasing temperature (hereinafter referred to as “thermal swelling”). ),
  • the heat-swellable resin D absorbs the electrolytic solution in the electrochemical element and swells greatly, and the swollen heat-swellable resin D closes the pores of the separator,
  • the temperature is higher than Tc, the liquid withering further proceeds due to thermal swellability, and the reaction of the battery is further suppressed, so that safety at high temperatures can be further enhanced.
  • the temperature at which the heat-swellable resin D starts to show heat-swellability is preferably 75 ° C. or higher.
  • the temperature (Tc) at which the internal resistance of the electrochemical element is increased by remarkably reducing the Li ion conductivity is about 80 ° C. This is because it can be set as described above.
  • the temperature at which the thermal swellable resin D starts to exhibit thermal swellability in order to set Tc to about 130 ° C. or lower is 125 ° C.
  • the temperature showing the thermal swellability is too high, the abnormal exothermic reaction of the active material in the electrochemical element may not be sufficiently suppressed, and the effect of improving the safety of the electrochemical element may not be sufficiently secured.
  • the conductivity of Li ions may be too low in the temperature range (about 70 ° C. or lower) of a normal electrochemical device.
  • the heat swellable resin D does not absorb the electrolyte solution as much as possible and has less swelling. This is because in an operating temperature range of an electrochemical element, for example, room temperature, the electrolyte is more likely to be held in a state where it can flow into the pores of the separator than to be taken into the heat-swellable resin D. This is because characteristics such as load characteristics are improved.
  • Electrolyte volume heat swelling resin D is absorbed at room temperature (25 ° C.) can be evaluated by the degree of swelling B R defined by the following equation represents the volume change of the thermal swelling resin D (1).
  • V 0 is the volume of the heat swelling resin D after 24 hours immersion at 25 ° C. in the electrolytic solution (cm 3)
  • V i is the thermal swelling resin before immersion in electrolyte solution
  • Each represents the volume (cm 3 ) of D.
  • the swelling degree B R of the heat-swellable resin D at room temperature (25 ° C.) is preferably 1 or less, it is less swelling due to absorption of the electrolyte solution it, i.e., B R it is desirable that the smallest possible value close to 0. Further, it is desirable that the temperature change of the degree of swelling is as small as possible on the lower temperature side than the temperature exhibiting thermal swellability.
  • the heat-swellable resin D when the heat-swellable resin D is heated to a temperature lower than the lower limit of the heat-swellable property, the amount of electrolyte absorbed increases, and in the temperature range showing the heat-swellability, Are used that increase. For example, it is measured at 120 ° C., swelling degree B T which is defined by the following formula (2) is, as 1 or higher is preferably used.
  • V 0 is the volume (cm 3 ) of the heat-swellable resin D after being immersed in an electrolytic solution at 25 ° C. for 24 hours
  • V 1 is after being immersed in the electrolytic solution at 25 ° C. for 24 hours.
  • the electrolyte solution is heated to 120 ° C., and the volume (cm 3 ) of the heat-swellable resin D after 1 hour at 120 ° C. is shown.
  • the degree of swelling of the heat-swellable resin D defined by the above formula (2) may be 10 or less because it may cause deformation of the electrochemical element if it becomes too large.
  • the degree of swelling defined by the above formula (2) is to directly measure the change in the size of the heat-swellable resin D using a method such as light scattering or image analysis of an image taken with a CCD camera. However, it can be measured more accurately using, for example, the following method.
  • a binder resin having a known degree of swelling at 25 ° C. and 120 ° C. which is defined in the same manner as in the above formulas (1) and (2), is mixed with the heat-swellable resin D in the solution or emulsion to form a slurry. It is prepared and applied onto a substrate such as a PET sheet or glass plate to produce a film, and its mass is measured. Next, the film was immersed in an electrolyte at 25 ° C. for 24 hours to measure the mass, and the electrolyte was heated to 120 ° C., and the mass after holding at 120 ° C. for 1 hour was measured. formula by (3) to (9) for calculating the swelling degree B T. In the following formulas (3) to (9), the volume increase of components other than the electrolytic solution when the temperature is raised from 25 ° C. to 120 ° C. can be ignored.
  • V i M i ⁇ W / P A (3)
  • V B (M 0 ⁇ M i ) / P B (4)
  • V C M 1 / P C ⁇ M 0 / P B (5)
  • V V M i ⁇ (1 ⁇ W) / P V (6)
  • V 0 V i + V B ⁇ V V ⁇ (B B +1) (7)
  • V D V V ⁇ (B B +1) (8)
  • B T ⁇ V 0 + V C ⁇ V D ⁇ (B C +1) ⁇ / V 0 ⁇ 1 (9)
  • V i Volume (cm 3 ) of the heat-swellable resin D before being immersed in the electrolytic solution
  • V 0 volume (cm 3 ) of the heat-swellable resin D after being immersed in the electrolyte at room temperature for 24 hours
  • V B volume of the electrolyte solution (cm 3 ) absorbed in the film after being immersed in the electrolyte solution at room temperature for 24 hours
  • V C The volume of the electrolyte solution absorbed by the film (cm) during the period from when it was immersed in the electrolyte solution at room temperature for 24 hours until the electrolyte solution was heated to 120 ° C. and further passed at 120 ° C. for 1 hour.
  • V V volume (cm 3 ) of the binder resin before being immersed in the electrolytic solution
  • V D volume of the binder resin (cm 3 ) after being immersed in the electrolytic solution at room temperature for 24 hours
  • M i mass (g) of the film before being immersed in the electrolytic solution
  • M 0 mass (g) of the film after being immersed in the electrolytic solution at room temperature for 24 hours
  • M 1 After immersing in the electrolytic solution at room temperature for 24 hours, the temperature of the electrolytic solution was raised to 120 ° C., and the mass (g) of the film after 1 hour at 120 ° C.
  • W Mass ratio of the heat-swellable resin D in the film before being immersed in the electrolytic solution
  • P A specific gravity (g / cm 3 ) of the heat-swellable resin D before being immersed in the electrolytic solution
  • P B Specific gravity of electrolyte at room temperature (g / cm 3 )
  • P C specific gravity of the electrolyte at a predetermined temperature (g / cm 3)
  • P V Specific gravity (g / cm 3 ) of the binder resin before being immersed in the electrolytic solution
  • B B degree of swelling of the binder resin after being immersed in the electrolyte at room temperature for 24 hours
  • B C is the degree of swelling of the binder resin at the time of temperature increase defined by the above formula (2).
  • V i and V 0 is determined from the said equation by the method (3) and the formula (7), can be determined swelling degree B R at room temperature using the above formula (1).
  • the electrochemical element of the present invention uses, for example, a solution obtained by dissolving a lithium salt in an organic solvent as a nonaqueous electrolyte, as in the case of conventionally known electrochemical elements (types of lithium salt and organic solvent). Details of the lithium salt concentration will be described later). Therefore, the heat-swellable resin D starts to show the above-mentioned heat-swellability when it reaches any temperature of 75 to 125 ° C. in an organic solvent solution of lithium salt. It is recommended that R and B T can swell so as to satisfy the above values.
  • the heat-swellable resin D is preferably an electrochemically stable material that has heat resistance and electrical insulation, is stable with respect to the electrolyte, and is not easily oxidized or reduced in the operating voltage range of the battery.
  • Examples of such a material include a crosslinked resin.
  • styrene resin polystyrene (PS), etc.), styrene butadiene rubber (SBR), acrylic resin (polymethyl methacrylate (PMMA), etc.), polyalkylene oxide (polyethylene oxide (PEO), etc.), fluororesin [ Polyvinylidene fluoride (PVDF) and the like] and a crosslinked product of at least one resin selected from the group consisting of these derivatives; urea resin; polyurethane; and the like.
  • the heat-swellable resin D the above exemplified resins may be used alone or in combination of two or more.
  • the heat-swellable resin D may contain various known additives that are added to the resin, for example, an antioxidant, as necessary.
  • crosslinked styrene resin a crosslinked acrylic resin, and a crosslinked fluororesin are preferable, and crosslinked PMMA is particularly preferably used.
  • the heat-swellable resin D is a resin having a Tg of about 75 to 125 ° C., considering that the temperature at which the shutdown action actually occurs is somewhat higher than the temperature at which the heat-swellable resin D starts to exhibit heat-swellability. It is considered desirable to use a crosslinked body.
  • Tg of the resin crosslinked body which is the heat-swellable resin D in this specification is a value measured using DSC in accordance with the provisions of JIS K7121.
  • the volume change accompanying the temperature change is reversible to some extent so that even if it expands due to the temperature rise, it shrinks again when the temperature is lowered.
  • a material that can be heated to 200 ° C or higher is used. You can choose. Therefore, even when heating is performed in a separator manufacturing process or the like, the resin is not dissolved or the thermal swellability of the resin is not impaired, and handling in a manufacturing process including a general heating process becomes easy.
  • the form of the heat-meltable resin C or the heat-swellable resin D (hereinafter, the heat-meltable resin C and the heat-swellable resin D may be collectively referred to as “shutdown resin”) is not particularly limited. It is preferable to use a shape having a particle diameter at the time of drying smaller than the thickness of the separator, and preferably has an average particle diameter of 1/100 to 1/3 of the thickness of the separator. Specifically, the average particle diameter is preferably 0.1 to 20 ⁇ m. When the particle diameter of the shutdown resin particles is too small, the gap between the particles becomes small, the ion conduction path becomes long, and the characteristics of the electrochemical device may be deteriorated.
  • the average particle diameter of the shutdown resin particles is determined by, for example, using a laser scattering particle size distribution analyzer (for example, “LA-920” manufactured by HORIBA) and dispersing the fine particles in a medium that does not swell the shutdown resin (for example, water). It can prescribe
  • the shutdown resin may be in a form other than the above, and may be present in a state of being laminated and integrated on the surface of another constituent element, for example, inorganic fine particles or a fibrous material. Specifically, it may exist as core-shell structured particles having inorganic fine particles as a core and a shutdown resin as a shell, or may be a multi-layered fiber having a shutdown resin on the surface of a core material. Furthermore, even if the separator is provided with a shutdown resin by forming a layer containing the shutdown resin (a layer formed only with the shutdown resin or a layer containing the shutdown resin and the binder) on one or both sides of the separator. Good.
  • the content of the shutdown resin in the separator is preferably as follows, for example, in order to make it easier to obtain the shutdown effect.
  • the volume of the shutdown resin in all the constituent components of the separator is preferably 10% by volume or more, and more preferably 20% by volume or more.
  • the volume of the shutdown resin in all the constituent components of the separator is preferably 50% by volume or less, and more preferably 40% by volume or less, from the viewpoint of securing the shape stability at high temperatures of the separator.
  • the separator of the present invention can be produced, for example, by the following methods (1) to (4).
  • the manufacturing method (1) of the separator includes monomers and oligomers for forming the resin A, a photopolymerization initiator, inorganic fine particles B, and particles of a heat-meltable resin C and a heat-swellable resin D as necessary.
  • a liquid composition in which these are dispersed in a volatile substance (volatile solvent) is prepared (monomer, oligomer, photopolymerization initiator may be dissolved in the volatile substance) ),
  • a porous substrate irradiating with light to form a separator-forming sheet, and then removing volatile substances by drying at a predetermined temperature to form pores.
  • a woven fabric composed of at least one kind of fibrous material containing the above-mentioned exemplified materials as constituent components, or a structure in which these fibrous materials are entangled with each other. Examples thereof include porous sheets such as non-woven fabrics. 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.
  • the volatile substance used in the liquid composition monomers and oligomers, photopolymerization initiators, those that can uniformly disperse or dissolve the inorganic fine particles B and the like are preferable, for example, aromatic hydrocarbons such as toluene, In general, organic solvents such as furans such as tetrahydrofuran and ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferably used. 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, water can be used as a volatile substance, and at this time, alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.) can be appropriately added to control the interfacial tension.
  • aromatic hydrocarbons such as toluene
  • organic solvents such as furans such
  • the photopolymerization initiator for example, 2,4,6-trimethylbenzoylbisphenylphosphine oxide, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, etc. should be used. Can do.
  • the amount of the photopolymerization initiator used is preferably 1 to 10 parts by mass with respect to 100 parts by mass of monomers and oligomers.
  • the solid content including monomers, oligomers, photopolymerization initiators, inorganic fine particles and the like is preferably 10 to 50% by mass, for example.
  • the separator production method (2) of the present invention comprises a monomer M or oligomer for forming the resin A, a photopolymerization initiator, inorganic fine particles B, and a material M that can be dissolved in a specific solvent X (preparation of a liquid composition).
  • a material that does not dissolve in the solvent Y used in the above) and a liquid composition (slurry or the like) in which particles of a heat-meltable resin C or a heat-swellable resin D are dispersed in the solvent Y if necessary.
  • solvent X for example, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, tetrahydrofuran, ⁇ -caprolactone and the like can be used.
  • the material M that can be dissolved in the specific solvent X for example, polyolefin resin, polyurethane resin, acrylic resin, or the like can be used. These materials are preferably used in the form of particles, for example, but the size and amount of use can be adjusted according to the porosity and pore size required for the separator.
  • the average particle size of the material is preferably 0.1 to 20 ⁇ m, and the amount used is the liquid composition
  • the total solid content in is preferably 1 to 10% by mass.
  • the same volatile substances that can be used in the liquid composition according to the production method (1) can be used.
  • the solid content of the liquid composition according to the production method (2) is preferably, for example, 10 to 50% by mass, as in the case of the production method (1).
  • the liquid composition according to the production method (2) can be controlled by using the same material as in the production method (1) to control the interfacial tension.
  • the separator production method (3) of the present invention is the same as the liquid composition according to the production method (1), which is applied on a substrate such as a film or metal foil, and irradiated with light to form a separator. In this method, after forming into a sheet, volatile substances are removed by drying at a predetermined temperature to form pores, and then peeled off from the substrate.
  • the liquid composition according to the production method (3) may contain a fibrous material, and the solid content including the fibrous material is preferably, for example, 10 to 50% by mass.
  • the separator manufacturing method (4) of the present invention is the same as the liquid composition according to the manufacturing method (2), applied on a substrate such as a film or metal foil, and irradiated with light to form a separator. After forming into a sheet, the material M is extracted with the specific solvent X to form pores, and then peeled off from the substrate.
  • the liquid composition according to the production method (4) may contain a fibrous material, and the solid content including the fibrous material is preferably, for example, 10 to 50% by mass.
  • the separator when manufacturing a separator by manufacturing method (3) or manufacturing method (4), the structure which integrated the separator and the electrode by using either the positive electrode which concerns on an electrochemical element, or a negative electrode as a base material It is good. In this case, the separator is not peeled off from the electrode serving as the base material.
  • the adhesion between the electrode mixture layer and the separator is high, so that the electrodes can be wound or laminated without peeling the separator from the electrode.
  • the highly flexible resin A is used, in the case of a non-aqueous electrolyte secondary battery using a wound body, it is possible to prevent a short circuit at the corner portion of the innermost periphery of the wound body.
  • the light irradiation conditions may be those employed in general photopolymerization. Specifically, for example, a high-pressure mercury lamp having a wavelength of 365 nm is used as an ultraviolet light source, and light irradiation is performed for 10 seconds at an irradiation intensity of 60 mW / cm 2 .
  • strength, irradiation time, etc. can be changed suitably.
  • the porosity of the separator is preferably 10% or more in order to ensure a sufficient amount of electrolyte solution and improve ion permeability in a dry state.
  • the separator porosity is preferably 70% or less in a dry state.
  • the porosity of the separator in a dry state P (%) is obtained from the thickness of the separator, the mass per area, and the density of the constituent components by using the following formula (10) to obtain the sum for each component i. Can be calculated.
  • a i ratio of component i expressed by mass%
  • ⁇ i density of component i (g / cm 3 )
  • m mass per unit area of separator (g / cm 2 )
  • t The thickness (cm) of the separator measured in a dry state.
  • the separator of the present invention is performed by a method according to JIS P 8117, and the 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 10 to 300 sec. It is desirable to be. If the Gurley value is too large, the ion permeability decreases, whereas if it is too small, the strength of the separator may decrease. Further, the strength of the separator is desirably 50 g or more in terms of piercing strength using a needle having a diameter of 1 mm. If the piercing strength is too small, a short circuit may occur due to the piercing of the separator when lithium dendrite crystals are generated. By employ
  • the thickness of the separator of the present invention is preferably 5 ⁇ m or more, more preferably 6 ⁇ m or more, from the viewpoint of more reliably separating the positive electrode and the negative electrode. It is still more preferable that it is above. On the other hand, if the separator is too thick, the energy density of the battery may be reduced. Therefore, the thickness is preferably 70 ⁇ m or less, more preferably 50 ⁇ m or less, and 30 ⁇ m or less. Is more preferable. In the case of a structure in which the separator and the electrode are integrated, the thickness of the separator refers to the thickness of the separator applied to one surface of the electrode.
  • the electrochemical device of the present invention only needs to have a non-aqueous electrolyte and the separator of the present invention, and there are no particular restrictions on other configurations and structures, and conventionally known electrochemical devices Various configurations and structures adopted in the above can be applied.
  • the electrochemical device of the present invention includes non-aqueous electrolyte secondary batteries, non-aqueous electrolyte primary batteries, supercapacitors, and the like, and can be preferably applied to applications that require safety at high temperatures.
  • the electrochemical device of the present invention is a non-aqueous electrolyte secondary battery will be described in detail.
  • non-aqueous electrolyte secondary battery examples include a cylindrical shape (such as a square cylindrical 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 for example, one having a structure in which a positive electrode mixture layer containing a positive electrode active material, a binder, a conductive additive and the like is provided on one side or both sides of a current collector can be used.
  • the material which can occlude / release Li ion used for the conventionally known nonaqueous electrolyte secondary battery can be used.
  • a lithium-containing transition metal oxide having a layered structure represented by Li 1 + x MO 2 ( ⁇ 0.1 ⁇ x ⁇ 0.1, M: Co, Ni, Mn, Al, Mg, etc.), LiMn 2 O 4 It is possible to use a spinel structure lithium manganese oxide in which a part of the element is substituted with another element, an olivine type compound represented by LiMPO 4 (M: Co, Ni, Mn, Fe, etc.), or the like.
  • lithium-containing transition metal oxide having a layered structure examples include LiCoO 2 and LiNi 1-x Co xy Al y O 2 (0.1 ⁇ x ⁇ 0.3, 0.01 ⁇ y ⁇ 0. 2) and other oxides containing at least Co, Ni and Mn (LiMn 1/3 Ni 1/3 Co 1/3 O 2 , LiMn 5/12 Ni 5/12 Co 1/6 O 2 , LiMn 3 / 5 Ni 1/5 Co 1/5 O 2 etc.).
  • a carbon material such as carbon black is used as the conductive auxiliary agent, and a fluorine resin such as PVDF is used as the binder, and the positive electrode mixture layer is formed by a positive electrode mixture in which these materials and a positive electrode active material are mixed. , Formed on the current collector.
  • a metal foil such as aluminum, a punching metal, a net, an expanded metal, or the like can be used.
  • an aluminum foil having a thickness of 10 to 30 ⁇ m is 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 non-aqueous electrolyte secondary battery, that is, a negative electrode containing a negative electrode active material capable of inserting and extracting Li ions.
  • a negative electrode active material lithium such as graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), carbon fibers, etc. can be occluded / released.
  • MCMB mesocarbon microbeads
  • One type or a mixture of two or more types of carbonaceous materials are used.
  • elements such as Si, Sn, Ge, Bi, Sb, In and alloys thereof, compounds that can be charged and discharged at a low voltage close to lithium metal such as lithium-containing nitrides or lithium-containing oxides, or lithium metal or lithium / aluminum
  • An alloy can also be used as the negative electrode active material.
  • a negative electrode mixture in which a conductive additive (carbon material such as carbon black) or a binder (PVDF or the like) or the like is appropriately added to these negative electrode active materials, and a molded body (negative electrode) using the current collector as a core material A mixture layer) or a laminate of the above various alloys and lithium metal foils alone or on a current collector is used.
  • 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 lead portion on the negative electrode side may be formed in the same manner as the lead portion on the positive electrode side.
  • the electrode can be used in the form of a stacked electrode group in which the positive electrode and the negative electrode are stacked via the separator of the present invention, or a wound electrode group in which the electrode is wound.
  • the separator of the present invention excellent in short circuit resistance at the time of bending is used, the effect is more effective when a wound electrode group that deforms the separator is used.
  • the flat wound electrode group that strongly bends the separator a wound electrode group having a flat cross section
  • the effect is particularly remarkable.
  • 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 hardly causes side reactions such as decomposition in a voltage range used as a battery.
  • LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 and other inorganic lithium salts 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 [wherein R f represents a fluoroalkyl group.
  • An organic lithium salt such as] can be used.
  • the organic solvent used for the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause a side reaction such as decomposition in a voltage range used as a battery.
  • cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and 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 dimethoxyethane, 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 Sulf
  • 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 1.3 mol / L.
  • the electrochemical device of the present invention can be used for the same applications as conventionally known electrochemical devices.
  • Example 1 Preparation of separator> Urethane acrylate as an oligomer: 3.5 parts by mass, dipentoxylated pentaerythritol diacrylate as a monomer (crosslinking agent): 3.5 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine as a photopolymerization initiator Oxide: 0.05 parts by mass, inorganic fine particle B boehmite (average particle size 0.6 ⁇ m): 32.95 parts by mass, and volatile substance toluene: 60 parts by mass for uniform mixing. A slurry was prepared.
  • a PET nonwoven fabric with a thickness of 12 ⁇ m is passed through the slurry, and the slurry is applied by pulling up and then passing through a gap having a predetermined interval, followed by irradiation with ultraviolet light having a wavelength of 365 nm for 10 seconds at an illuminance of 60 mW / cm 2. Then, it was dried to remove toluene, and a separator having a thickness of 16 ⁇ m was obtained.
  • a negative electrode active material-containing paste was prepared by mixing 95 parts by mass of graphite serving as the negative electrode active material and 5 parts by mass of PVDF so as to be uniform using NMP as a solvent. This paste is intermittently applied to both sides of a 10 ⁇ m thick collector made of copper foil so that the coating length is 290 mm on the front and 230 mm on the back, dried, and then calendered to a total thickness of 142 ⁇ m. The negative electrode mixture layer was adjusted in thickness and cut to a width of 45 mm to prepare a negative electrode. Then, tab attachment was performed to the exposed part of the copper foil in a negative electrode.
  • ⁇ Battery assembly> The positive electrode and the negative electrode obtained as described above were overlapped with the separator interposed therebetween and wound in a spiral shape to produce a wound body electrode group.
  • the obtained wound body electrode group is crushed into a flat shape, put into an aluminum outer can having a thickness of 4 mm, a height of 50 mm, and a width of 34 mm, and an electrolytic solution (ethylene carbonate and ethyl methyl carbonate are mixed in a volume ratio of 1: 2).
  • an electrolytic solution ethylene carbonate and ethyl methyl carbonate are mixed in a volume ratio of 1: 2.
  • FIG. 1A is a plan view of the nonaqueous electrolyte secondary battery of this example
  • FIG. 1B is a cross-sectional view of FIG. 1A
  • the positive electrode 1 and the negative electrode 2 are housed in a rectangular outer can 4 together with a non-aqueous electrolyte as a wound body electrode group 6 wound in a spiral shape through the separator 3 as described above.
  • a metal foil, an electrolytic solution, and the like as a current collector used for manufacturing the positive electrode 1 and the negative electrode 2 are not illustrated.
  • the outer can 4 is made of an aluminum alloy and constitutes the outer casing of the battery.
  • the outer can 4 also serves as a positive electrode terminal.
  • the insulator 5 which consists of a polyethylene sheet is arrange
  • the positive electrode lead body 7 and the negative electrode lead body 8 are drawn out.
  • a stainless steel terminal 11 is attached to an aluminum alloy cover plate 9 that seals the opening of the outer can 4 via a polypropylene insulating packing 10, and an insulator 12 is connected to the terminal 11.
  • a stainless steel lead plate 13 is attached.
  • the cover plate 9 is inserted into the opening of the outer can 4 and welded to join the opening of the outer can 4 so that the inside of the battery is sealed.
  • the lid plate 9 is provided with an electrolyte inlet 14, and when the battery is assembled, the electrolyte is injected into the battery from the electrolyte inlet 14, and then the electrolyte inlet 14 is sealed. Stopped.
  • the cover plate 9 is provided with an explosion-proof safety valve 15.
  • the outer can 4 and the lid plate 9 function as a positive electrode terminal by directly welding the positive electrode lead body 7 to the lid plate 9, and the negative electrode lead body 8 is welded to the lead plate 13.
  • the terminal 11 functions as a negative electrode terminal by conducting the negative electrode lead body 8 and the terminal 11 through the lead plate 13, but depending on the material of the outer can 4, the sign may be reversed. There is also.
  • FIG. 2 is a perspective view schematically showing the external appearance of the battery shown in FIGS. 1A and 1B.
  • FIG. 2 is shown for the purpose of showing that the battery is a square battery.
  • a battery is schematically shown, and only specific ones of the constituent members of the battery are illustrated.
  • the inner peripheral side portion of the wound body electrode group 6 is not cross-sectioned, and the cross-section hatching is omitted in the separator 3.
  • Example 2 Urethane acrylate as an oligomer: 15 parts by mass, dipentoxylated pentaerythritol diacrylate as a monomer: 15 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine oxide as a photopolymerization initiator: 0.15 parts by mass, Except for using a separator-forming slurry prepared by uniformly mixing 10 parts by weight of boehmite as an inorganic fine particle B (average particle size 0.6 ⁇ m) and 59.85 parts by weight of toluene as a volatile substance. A separator was produced in the same manner as in Example 1. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
  • Example 3 A slurry for forming a separator was prepared in the same manner as in Example 1 except that the inorganic fine particles B were changed to titania (average particle size 0.6 ⁇ m), and the same procedure as in Example 1 was performed except that this slurry was used. A separator was produced. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
  • Example 4 A separator-forming slurry was prepared in the same manner as in Example 1 except that the inorganic fine particles B were changed to alumina (average particle size 0.4 ⁇ m), and the slurry was used in the same manner as in Example 1 except that this slurry was used. A separator was produced. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
  • Example 5 The same slurry for forming a separator as that prepared in Example 1 was applied to the surface of a polytetrafluoroethylene substrate with a gap of 40 ⁇ m using a die coater, followed by UV irradiation at an illuminance of 60 mW / cm 2 at 10. Irradiated for 2 seconds, dried, and then peeled off from the substrate to obtain a separator having a thickness of 16 ⁇ m.
  • a nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • a PET nonwoven fabric having a thickness of 12 ⁇ m is passed through this slurry, and after applying the slurry by pulling up, it is passed through a gap having a predetermined interval, followed by irradiation with ultraviolet rays at an illuminance of 60 mW / cm 2 for 10 seconds, and then It dried and obtained the porous membrane whose thickness is 12 micrometers. Thereafter, an emulsion containing PE fine particles (average particle diameter of PE fine particles of 1.0 ⁇ m) is applied to one side of the porous film with a die coater so that the thickness after drying becomes 4 ⁇ m, and dried to form a shutdown layer. To obtain a separator. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this separator was used.
  • Example 7 Urethane acrylate as an oligomer: 15.7 parts by mass, isobornyl acrylate as a monomer (crosslinking agent): 10.4 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine oxide as a photopolymerization initiator: 0 .78 parts by mass, Boehmite as an inorganic fine particle B (average particle size 0.6 ⁇ m): 23.5 parts by mass, and toluene as a volatile substance: 49.62 parts by mass for uniform mixing A separator was prepared in the same manner as in Example 1 except that this slurry was used. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
  • Example 8 The same slurry for forming the separator as that prepared in Example 1 was applied on the negative electrode similarly prepared in Example 1 with a gap of 40 ⁇ m using a die coater. After the application, ultraviolet rays were irradiated at an illuminance of 60 mW / cm 2 for 10 seconds and further dried to obtain an electrode (negative electrode) having a separator formed on the negative electrode mixture layer.
  • the separator was formed on both sides of the negative electrode, and the thickness of the layer in which the negative electrode mixture layer and the separator were integrated was 70 ⁇ m on both sides of the negative electrode current collector.
  • the electrode (negative electrode) integrated with the separator and the positive electrode prepared in Example 1 are stacked without interposing another separator therebetween, and wound to form a wound electrode group. did. Thereafter, a nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.
  • Example 9 The same slurry for forming a separator as that prepared in Example 1 was applied on the negative electrode similarly prepared in Example 1 with a gap of 3 ⁇ m using a die coater. After the application, ultraviolet rays were irradiated at an illuminance of 60 mW / cm 2 for 10 seconds and further dried to obtain an electrode (negative electrode) having a separator formed on the negative electrode mixture layer. The separator was formed on both sides of the negative electrode, and the thickness of the layer in which the negative electrode mixture layer and the separator were integrated was 5 ⁇ m on each side of the negative electrode current collector.
  • the electrode (negative electrode) integrated with the separator and the positive electrode prepared in Example 1 are stacked without interposing another separator therebetween, and wound to form a wound electrode group. did. Thereafter, a nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.
  • Example 3 A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that a PE microporous membrane having a thickness of 16 ⁇ m was used as the separator.
  • This slurry was applied on the negative electrode prepared in Example 1 with a gap of 9 ⁇ m using a die coater. After the application, ultraviolet rays were irradiated at an illuminance of 60 mW / cm 2 for 10 seconds and further dried to obtain an electrode (negative electrode) having a separator formed on the negative electrode mixture layer.
  • the separator was formed on both sides of the negative electrode, and the thickness of the layer in which the negative electrode mixture layer and the separator were integrated was 16 ⁇ m on each side of the negative electrode current collector.
  • the electrode (negative electrode) integrated with the separator and the positive electrode prepared in Example 1 are stacked without interposing another separator therebetween, and wound to form a wound electrode group. did. Thereafter, a nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.
  • Table 1 shows the configurations of the separators used in the nonaqueous electrolyte secondary batteries of Examples 1 to 9 and Comparative Examples 1 to 4.
  • a / b value means the ratio a / b between the volume a of the resin A (volume excluding the void volume) and the volume b of the inorganic fine particle B (volume excluding the void volume). It means that “the total amount of resin A and inorganic fine particles B” means the volume a of resin A (volume excluding pore volume) and inorganic relative to the total volume (volume excluding pore volume) of the constituent components of the separator. It means the ratio of the total volume with the volume b (volume excluding pore volume) of the fine particles B.
  • each separator in Example 8 and 9, negative electrode integrated separator was held in a thermostat at 150 ° C. for 1 hour, and the dimensions (width and length) before holding were compared with the dimensions after holding. As a result, no dimensional change was observed, and it was confirmed that the separator was able to prevent a decrease in battery safety due to shrinkage at high temperatures.
  • Example 6 and Comparative Example 3 using the separator having the shutdown resin for the shutdown characteristics evaluation, after charging under the same conditions as those during the charge / discharge test, the batteries were put into a thermostatic bath and from 30 ° C. The temperature was raised to 150 ° C. at a rate of 1 ° C. per minute, and the temperature was changed by measuring the internal resistance of the battery. The temperature at which the resistance value increased to 5 times or more the value at 30 ° C. was taken as the shutdown temperature of the separator. Further, after the temperature of the battery reached 150 ° C., a temperature increase test was performed in which the temperature of the thermostatic bath was maintained at 150 ° C. for 2 hours. During the temperature increase test, the state of the battery was observed and the maximum temperature reached by the battery was measured. Further, the voltage of the battery after the temperature increase test was measured. The above results are shown in Table 3.
  • the electrolyte secondary battery did not cause a fine short circuit and had good charge / discharge characteristics.
  • the separators used in the batteries of Examples 1 to 9 are excellent in dimensional stability at high temperatures, as shown in Table 3, the nonaqueous electrolyte secondary battery of Example 6 is Since the voltage drop after the temperature increase test is small and the shutdown function can be effectively operated, the temperature increase during the temperature increase test is suppressed, and high reliability and safety are obtained.
  • a slight short circuit occurred during charging in the charge / discharge test are because the battery of Comparative Example 1 lacks the flexibility of the separator, and the battery of Comparative Example 2 lacks short-circuit resistance between the positive and negative electrodes due to the small amount of inorganic fine particles B in the separator. It is guessed.
  • the separator used in the batteries of Examples 1 to 7 and the separator integrated electrode used in the batteries of Examples 8 and 9 can be manufactured by only a simple process, the separator and the battery (electrochemical element) ) Productivity.

Abstract

This separator for an electrochemical element is characterized in comprising a resin (A) formed by photopolymerization and provided with a bridge structure, and an electrically insulating inorganic fine particles (B), the ratio a/b of the volume (a) of the resin (A) and the volume (b) of the inorganic particles (B), excluding the pore volume, being 0.6-9. This method for manufacturing a separator for an electrochemical element is characterized in comprising a step for forming pores by vaporizing a volatile substance from a sheet for forming a separator for an electrochemical element containing the volatile substance, or a step for forming pores by extracting a material with a specific solvent from a sheet for forming a separator for an electrochemical element containing the material soluble in the solvent.

Description

電気化学素子用セパレータとその製造方法、電気化学素子用電極および電気化学素子Electrochemical element separator and method for producing the same, electrochemical element electrode and electrochemical element
　本発明は、高温時の寸法安定性および折り曲げ時の耐短絡性に優れた電気化学素子用セパレータとその製造方法、前記セパレータと一体化された電気化学素子用電極、および前記電気化学素子用セパレータを有しており、高温環境下においても安全な電気化学素子に関するものである。 The present invention relates to an electrochemical element separator excellent in dimensional stability at high temperature and short circuit resistance during bending, a method for producing the same, an electrode for electrochemical element integrated with the separator, and the separator for electrochemical element The present invention relates to an electrochemical element that is safe even in a high temperature environment.
　リチウム二次電池などの非水電解質二次電池やスーパーキャパシタに代表される非水電解質を用いた電気化学素子は、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おり、携帯機器の高性能化に伴って電気化学素子の高容量化が更に進む傾向にあり、更なる安全性の確保が重要な課題となっている。 Electrochemical elements using non-aqueous electrolytes such as lithium secondary batteries and non-aqueous electrolytes typified by supercapacitors are characterized by high energy density, and are used in mobile devices such as mobile phones and notebook personal computers. It is widely used as a power source, and there is a tendency that the capacity of the electrochemical device is further increased along with the improvement of the performance of the portable device, and ensuring further safety is an important issue.
　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多孔性フィルムが使用されている。しかし、このようなポリオレフィン系の多孔性フィルムを製造する際には、微細且つ均一な孔を開けるために、二軸延伸または開孔剤の抽出などの複雑な工程が用いられ、コストが高く、セパレータが高価になっていることが現状である。 In current lithium secondary batteries, a polyolefin-based porous film having a thickness of about 20 to 30 μm is used as a separator interposed between a positive electrode and a negative electrode. However, when producing such a polyolefin-based porous film, a complicated process such as biaxial stretching or extraction of a pore opening agent is used in order to open fine and uniform holes, and the cost is high. The current situation is that separators are expensive.
　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、融点が１２０～１４０℃程度のポリエチレンが用いられている。しかし、シャットダウン後の電池の温度が更に上昇した場合など、溶融したポリエチレンが流れやすくなり、セパレータが破膜する所謂メルトダウンが生じることがある。そのような場合には、正負極が直接接触し、更に温度が上昇する危険性がある。 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 the so-called shutdown effect, polyethylene having a melting point of about 120 to 140 ° C. is used. However, when the temperature of the battery after the shutdown further increases, so-called meltdown in which the melted polyethylene easily flows and the separator breaks may occur. In such a case, there is a risk that the positive and negative electrodes are in direct contact and the temperature further increases.
　このようなメルトダウンによる短絡を防ぐために、耐熱性の樹脂を用いた微多孔膜や不織布をセパレータとして用いる方法が提案されている。例えば、特許文献１には全芳香族ポリアミドの微多孔膜を用いたセパレータが、特許文献２にはポリイミド多孔膜を用いたセパレータが開示されている。また、特許文献３にはポリアミド不織布を用いたセパレータ、特許文献４にはアラミド繊維を用いた不織布を基材としたセパレータに関する技術が開示されている。しかし、このような耐熱微多孔膜や不織布を用いる時、材料のコストまたは製造の難しさなどが問題となる。 In order to prevent such a short circuit due to meltdown, a method of using a microporous film or a nonwoven fabric using a heat-resistant resin as a separator has been proposed. For example, Patent Document 1 discloses a separator using a wholly aromatic polyamide microporous film, and Patent Document 2 discloses a separator using a polyimide porous film. Patent Document 3 discloses a technique related to a separator using a polyamide nonwoven fabric, and Patent Document 4 discloses a technique related to a separator based on a nonwoven fabric using aramid fibers. However, when such a heat-resistant microporous membrane or nonwoven fabric is used, the cost of the material or difficulty in manufacturing becomes a problem.
　一方、特許文献５には、ポリマー不織布基材の上および中に多孔性の無機被覆を有するセパレータに関する技術が開示されている。このようなセパレータは、耐熱性に優れる一方で柔軟性に乏しい無機被覆を採用しているため、巻回体を用いる電気化学素子に適用する際に、折り曲げによるひび割れが生じて短絡する虞がある。特に、角形電池のような扁平状の巻回体を用いる電気化学素子においては、強烈な折り曲げが発生するため、このようなセパレータの適用が非常に困難である。 On the other hand, Patent Document 5 discloses a technique relating to a separator having a porous inorganic coating on and in a polymer nonwoven fabric substrate. Since such a separator employs an inorganic coating that is excellent in heat resistance but lacks flexibility, when applied to an electrochemical element using a wound body, there is a risk that a crack will occur due to bending and a short circuit may occur. . In particular, in an electrochemical element using a flat wound body such as a square battery, intense bending occurs, and thus such a separator is very difficult to apply.
特開平５－３３５００５号公報JP-A-5-335005 特開２０００－３０６５６８号公報JP 2000-306568 A 特開平９－２５９８５６号公報JP-A-9-259856 特開平１１－４０１３０号公報Japanese Patent Laid-Open No. 11-40130 特表２００６－５０４２２８号公報JP-T-2006-504228
　こうしたことから、コストや製造工程の面で生産性を損なうことなく、セパレータの寸法安定性や折り曲げ時の耐短絡性を向上させて、これを用いた電気化学素子の安全性や信頼性を高める技術の開発が求められる。 Therefore, without sacrificing productivity in terms of cost and manufacturing process, the dimensional stability of the separator and the short circuit resistance during bending are improved, and the safety and reliability of the electrochemical device using this are improved. Technology development is required.
　本発明は、前記事情に鑑みてなされたものであり、信頼性および高温下での安全性に優れた電気化学素子、該電気化学素子を構成し得るセパレータおよびその製造方法を提供する。 The present invention has been made in view of the above circumstances, and provides an electrochemical element excellent in reliability and safety at high temperatures, a separator that can constitute the electrochemical element, and a method for manufacturing the same.
　本発明の電気化学素子用セパレータは、光重合により形成され、架橋構造を有する樹脂Ａと、電気絶縁性の無機微粒子Ｂとを含む電気化学素子用セパレータであって、空孔体積を除き、前記樹脂Ａの体積ａと、前記無機微粒子Ｂの体積ｂとの比ａ／ｂが、０．６～９であることを特徴とする。 The separator for an electrochemical element of the present invention is a separator for an electrochemical element that is formed by photopolymerization and includes a resin A having a cross-linked structure and electrically insulating inorganic fine particles B, except for the pore volume, The ratio a / b between the volume a of the resin A and the volume b of the inorganic fine particles B is 0.6 to 9.
　また、本発明の電気化学素子用セパレータの製造方法は、上記本発明の電気化学素子用セパレータの製造方法であって、揮発性物質を含む電気化学素子用セパレータ形成用のシートから、前記揮発性物質を揮発させて空孔を形成する工程、または、特定の溶剤に溶解し得る材料を含む電気化学素子用セパレータ形成用のシートから、前記溶剤により前記材料を抽出することで空孔を形成する工程を含むことを特徴とする。 The method for producing an electrochemical element separator of the present invention is the method for producing an electrochemical element separator of the present invention, wherein the volatile material is formed from a sheet for forming an electrochemical element separator containing a volatile substance. The step of volatilizing a substance to form pores, or the formation of pores by extracting the material with the solvent from a sheet for forming an electrochemical element separator containing a material that can be dissolved in a specific solvent Including a process.
　また、本発明の電気化学素子用電極は、上記本発明の電気化学素子用セパレータと一体化されたことを特徴とする。 The electrochemical element electrode of the present invention is characterized by being integrated with the electrochemical element separator of the present invention.
　また、本発明の電気化学素子は、正極、負極、セパレータおよび非水電解質を含む電気化学素子であって、前記セパレータが、上記本発明の電気化学素子用セパレータであることを特徴とする。 The electrochemical element of the present invention is an electrochemical element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the separator is the separator for an electrochemical element of the present invention.
　本発明によれば、電気化学素子の信頼性および高温下での安全性を向上させることができる。 According to the present invention, the reliability of the electrochemical device and the safety at high temperatures can be improved.
図１Ａは、本発明の電気化学素子（非水電化質二次電池）の一例を示す平面図であり、図１Ｂは、図１Ａの断面図である。FIG. 1A is a plan view showing an example of an electrochemical element (non-aqueous electrolyte secondary battery) of the present invention, and FIG. 1B is a cross-sectional view of FIG. 1A. 図２は、本発明の電気化学素子の一例を示す斜視図である。FIG. 2 is a perspective view showing an example of the electrochemical element of the present invention.
　本発明の電気化学素子用セパレータ（以下、単に「セパレータ」という。）は、非水電解質を有する電気化学素子のセパレータに使用されるものであり、光重合により形成され、少なくとも一部に架橋構造を有する樹脂Ａと、電気絶縁性の無機微粒子Ｂとを含有している。 The separator for an electrochemical element of the present invention (hereinafter simply referred to as “separator”) is used for a separator of an electrochemical element having a non-aqueous electrolyte, and is formed by photopolymerization and has a crosslinked structure at least partially. A resin A having electrical conductivity and electrically insulating inorganic fine particles B.
　また、本発明のセパレータにおいては、樹脂Ａの体積をａ（空孔体積を除いた体積）、無機微粒子Ｂの体積をｂ（空孔体積を除いた体積）との比ａ／ｂが、０．６以上９以下である。このように、本発明のセパレータでは、樹脂Ａおよび無機微粒子Ｂの組成比を適正化することで、セパレータの柔軟性と、機械的強度や耐熱収縮性とを良好に確保して、信頼性および高温下での安全性に優れた電気化学素子を構成し得るものとしている。 In the separator of the present invention, the ratio a / b of the volume of the resin A to a (volume excluding the void volume) and the volume of the inorganic fine particles B to b (volume excluding the void volume) is 0. .6 or more and 9 or less. As described above, in the separator of the present invention, by optimizing the composition ratio of the resin A and the inorganic fine particles B, the flexibility of the separator, the mechanical strength and the heat shrinkability can be ensured satisfactorily. It is supposed that an electrochemical element excellent in safety at a high temperature can be constituted.
　すなわち、本発明のセパレータでは、前記ａ／ｂ値を、０．６以上、好ましくは３以上とすることで、柔軟性に富む樹脂Ａの作用によって、例えば、巻回体電極群（特に角形電池などに使用される横断面が扁平状の巻回体電極群）を構成する場合のように折り曲げた場合にも、ひび割れなどの欠陥の発生を抑え得るようにして、耐短絡性に優れたセパレータとしている。 That is, in the separator of the present invention, by setting the a / b value to 0.6 or more, preferably 3 or more, for example, a wound electrode group (especially a prismatic battery) can be obtained by the action of the resin A rich in flexibility. A separator with excellent short-circuit resistance that can suppress the occurrence of defects such as cracks even when it is bent as in the case of a flat wound body electrode group) It is said.
　また、本発明のセパレータでは、柔軟性に富む樹脂を用いているため、電極上に塗布して形成した形態のセパレータであっても、セパレータによる収縮がなく、更に、ロール・ツウ・ロールによるセパレータの製造過程において、ひび割れ等の欠陥がなく、非常に生産性に優れている。 Further, since the separator of the present invention uses a resin having a high flexibility, even a separator formed by coating on an electrode is not contracted by the separator, and further, a roll-to-roll separator. In the manufacturing process, there are no defects such as cracks, and the productivity is excellent.
　また、本発明のセパレータでは、前記ａ／ｂ値を、９以下、好ましくは８以下とすることで、無機微粒子Ｂの機能を有効に引き出し得るようにして、高温時の寸法安定性を高めて耐熱収縮性に優れ、また、高い強度（機械的強度）などを確保することで耐短絡性に優れたセパレータとしている。 In the separator of the present invention, by setting the a / b value to 9 or less, preferably 8 or less, the function of the inorganic fine particles B can be effectively extracted, and the dimensional stability at high temperature is improved. The separator is excellent in heat-shrinkage resistance and has excellent short-circuit resistance by ensuring high strength (mechanical strength) and the like.
　よって、これらの作用を有する本発明のセパレータを用いて構成される本発明の電気化学素子は、信頼性および高温下での安全性が良好となる。 Therefore, the electrochemical element of the present invention constituted by using the separator of the present invention having these functions has good reliability and safety at high temperatures.
　なお、本発明において、樹脂Ａの体積ａは、樹脂Ａの密度とセパレータ中の樹脂Ａの質量とから算出される値であり、無機微粒子Ｂの体積ｂは、無機微粒子Ｂの密度とセパレータ中の無機微粒子Ｂの質量とから算出される値である。 In the present invention, the volume a of the resin A is a value calculated from the density of the resin A and the mass of the resin A in the separator, and the volume b of the inorganic fine particles B is the density of the inorganic fine particles B and the separator. It is a value calculated from the mass of the inorganic fine particles B.
　本発明のセパレータに係る樹脂Ａは、光重合により形成されるものである。このような樹脂Ａであれば、セパレータの製造を簡易なものとでき、かつ製造時間も短くし得るため、セパレータの生産性を高めることができる。 The resin A according to the separator of the present invention is formed by photopolymerization. With such a resin A, the separator can be manufactured easily and the manufacturing time can be shortened, so that the productivity of the separator can be increased.
　なお、樹脂Ａは、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およびガラス転移温度が、電気化学素子の通常使用温度の範囲外であることが好ましい。より具体的には、樹脂Ａのガラス転移温度は、０℃以下であることが好ましく、－１０℃以下であることがより好ましい。また、樹脂Ａの融解温度は、８０℃以上であることが好ましく、１００℃以上であることがより好ましい。 In addition, resin A has a melting temperature and a glass transition temperature measured using a differential scanning calorimeter (DSC) in accordance with the provisions of Japanese Industrial Standard (JIS) K 7121. Preferably outside. More specifically, the glass transition temperature of the resin A is preferably 0 ° C. or lower, and more preferably −10 ° C. or lower. Further, the melting temperature of the resin A is preferably 80 ° C. or higher, and more preferably 100 ° C. or higher.
　このような樹脂Ａとしては、公知のモノマーやオリゴマーを光重合して形成されるものが挙げられる。具体的には、例えば、アクリル樹脂モノマー［メチルメタクリレート、メチルアクリレートなどのアルキル（メタ）アクリレートおよびその誘導体］およびこれらのオリゴマーと、架橋剤とから形成されるアクリル樹脂；ウレタンアクリレートと架橋剤とから形成される架橋樹脂；エポキシアクリレートと架橋剤とから形成される架橋樹脂；などが挙げられる。なお、前記のいずれの樹脂においても、架橋剤としては、ジオキサングリコールジアクリレート、トリシクロデカンジメタノールジアクリレート、エチレンオキサイド変性トリメチロールプロパントリアクリレート、ジペンタエリスリトールペンタアクリレート、カプロラクトン変性ジペンタエリスリトールヘキサアクリレート、ε－カプロラクトン変性ジペンタエリスリトールヘキサアクリレートなどの、２価または多価のアクリルモノマーを用いることができる。 Examples of such resin A include those formed by photopolymerization of known monomers and oligomers. Specifically, for example, an acrylic resin formed from an acrylic resin monomer [alkyl (meth) acrylate such as methyl methacrylate and methyl acrylate and derivatives thereof] and oligomers thereof and a crosslinking agent; urethane acrylate and a crosslinking agent And a crosslinked resin formed from an epoxy acrylate and a crosslinking agent. In any of the above resins, the crosslinking agent includes dioxane glycol diacrylate, tricyclodecane dimethanol diacrylate, ethylene oxide modified trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, caprolactone modified dipentaerythritol hexaacrylate. Divalent or polyvalent acrylic monomers such as ε-caprolactone-modified dipentaerythritol hexaacrylate can be used.
　また、樹脂Ａには、２価または多価のアルコールとジカルボン酸とを縮重合によって製造されたエステル組成物とスチレンモノマーの混合物とから光重合により形成される不飽和ポリエステル樹脂由来の架橋樹脂；多官能エポキシ、多官能オキセタンまたはこれらの混合物から光重合により形成される樹脂；ポリイソシアネートとポリオールとの光重合反応によって生成する各種ポリウレタン樹脂；なども用いることができる。 In addition, the resin A includes a crosslinked resin derived from an unsaturated polyester resin formed by photopolymerization from a mixture of an ester composition prepared by condensation polymerization of a divalent or polyvalent alcohol and a dicarboxylic acid and a styrene monomer; Resins formed by photopolymerization from polyfunctional epoxy, polyfunctional oxetane or a mixture thereof; various polyurethane resins produced by photopolymerization reaction of polyisocyanate and polyol; and the like can also be used.
　なお、前記の多官能エポキシとしては、例えば、エチレングリコールジグリシジルエーテル、１，６－ヘキサンジオールジグリジルエーテル、ネオペンチルグリコールジグリジルエーテル、グリセロールポリグリシジルエーテル、ソルビトールグリシジルエーテル、３，４－エポキシシクロヘキセニルメチル－３’，４’－エポキシシクロヘキセンカルボキシレート、１，２：８，９ジエポキシリモネンなどが挙げられる。また、前記の多官能オキセタンとしては、例えば、３－エチル－３｛［（３－エチルオキセタン－３－イル）メトキシ］メチル｝オキセタン、キシレンビスオキセタンなどが挙げられる。 Examples of the polyfunctional epoxy include ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerol polyglycidyl ether, sorbitol glycidyl ether, and 3,4-epoxycyclohexane. Examples include hexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate and 1,2: 8,9 diepoxy limonene. Examples of the polyfunctional oxetane include 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane and xylene bisoxetane.
　更に、前記のポリイソシアネートとしては、例えば、ヘキサメチレンジイソシアネート、フェニレンジイソシアネート、トルエンジイソシアネート（ＴＤＩ）、４，４’－ジフェニルメタンジイソシアネート（ＭＤＩ）、イソホロンジイソシアネート（ＩＰＤＩ）またはビス－（４－イソシアナトシクロヘキシル）メタンなどが挙げられる。また、前記のポリオールとしては、例えば、ポリエーテルポリオール、ポリカーボネートポリオール、ポリエステルポリオールなどが挙げられる。 Further, examples of the polyisocyanate include hexamethylene diisocyanate, phenylene diisocyanate, toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) or bis- (4-isocyanatocyclohexyl). Examples include methane. Moreover, as said polyol, polyether polyol, polycarbonate polyol, polyester polyol etc. are mentioned, for example.
　なお、前記の各樹脂の形成（光重合）に際しては、イソボルニルアクリレート、メトキシポリエチレングリコールアクリレート、フェノキシポリエチレングリコールアクリレートなど単官能モノマーを併用することもできる。特に、イソボルニルアクリレートを併用した場合には、柔軟性と強度とのバランスがより良好な樹脂Ａを形成することができることから、好ましい。 In the formation (photopolymerization) of each of the above resins, a monofunctional monomer such as isobornyl acrylate, methoxy polyethylene glycol acrylate, or phenoxy polyethylene glycol acrylate can be used in combination. In particular, when isobornyl acrylate is used in combination, a resin A having a better balance between flexibility and strength can be formed.
　本発明のセパレータに係る無機微粒子Ｂは、セパレータの強度や寸法安定性を高めるなどして耐短絡性向上に寄与する成分である。また、無機微粒子Ｂによって、セパレータの空孔率や孔径の制御を容易とすることができる。無機微粒子Ｂとしては、電気絶縁性と、１５０℃以上の温度下で反応および変形しない耐熱性とを有し、電気化学素子の有する非水電解質やセパレータ製造の際に使用する溶剤（後述する）に対して安定であり、更に電気化学素子の作動電圧範囲において酸化還元されにくい電気化学的に安定なものであれば、特に制限はない。 The inorganic fine particles B according to the separator of the present invention are components that contribute to improvement of short circuit resistance by increasing the strength and dimensional stability of the separator. Further, the inorganic fine particles B can easily control the porosity and the pore diameter of the separator. The inorganic fine particles B have electrical insulating properties and heat resistance that does not react and deform at temperatures of 150 ° C. or higher, and are used in the production of non-aqueous electrolytes and separators in electrochemical devices (described later). As long as it is electrochemically stable and resistant to oxidation and reduction within the operating voltage range of the electrochemical element, there is no particular limitation.
　無機微粒子Ｂの具体例としては、酸化鉄、シリカ（ＳｉＯ２）、アルミナ（Ａｌ２Ｏ３）、ＴｉＯ２（チタニア）、ＢａＴｉＯ３などの無機酸化物微粒子；窒化アルミニウム、窒化ケイ素などの無機窒化物微粒子；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；モンモリロナイトなどの粘土微粒子；などが挙げられる。ここで、前記無機酸化物微粒子は、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、マイカなどの鉱物資源由来物質またはこれらの人造物などの微粒子であってもよい。また、金属、ＳｎＯ２、スズ－インジウム酸化物（ＩＴＯ）などの導電性酸化物またはカーボンブラック、グラファイトなどの炭素質材料などで例示される導電性材料の表面を、電気絶縁性を有する材料（例えば、前記の無機酸化物など）で被覆することにより電気絶縁性を持たせた粒子であってもよい。無機微粒子Ｂは、前記例示のものを１種単独で使用してもよく、２種以上を併用してもよい。前記例示の無機微粒子Ｂの中でも、無機酸化物微粒子がより好ましく、アルミナ、チタニア、シリカ、ベーマイトが更に好ましい。 Specific examples of the inorganic fine particles B include inorganic oxide fine particles such as iron oxide, silica (SiO 2 ), alumina (Al 2 O 3 ), TiO 2 (titania), BaTiO 3 ; inorganic nitride such as aluminum nitride and silicon nitride. Such as calcium fluoride, barium fluoride, barium sulfate, and the like; insoluble crystal particles such as silicon and diamond; clay particles such as montmorillonite; Here, the inorganic oxide fine particles may be fine particles such as boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, or a mineral resource-derived material or an artificial product thereof. In addition, the surface of a conductive material exemplified by a metal, SnO 2 , a conductive oxide such as tin-indium oxide (ITO) or a carbonaceous material such as carbon black or graphite, and the like has an electrically insulating material ( For example, the particle | grains which gave the electrical insulation property by coat | covering with the said inorganic oxide etc. may be sufficient. As the inorganic fine particles B, those exemplified above may be used alone or in combination of two or more. Among the exemplified inorganic fine particles B, inorganic oxide fine particles are more preferable, and alumina, titania, silica, and boehmite are more preferable.
　無機微粒子Ｂの粒径は、平均粒径で、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。なお、無機微粒子Ｂの平均粒径は、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、無機微粒子Ｂを溶解しない媒体に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。 The average particle diameter of the inorganic fine particles B is preferably 0.001 μm or more, more preferably 0.1 μm or more, and preferably 15 μm or less, and preferably 1 μm or less. More preferred. The average particle size of the inorganic fine particles B is, for example, the number average particle size measured by dispersing the inorganic fine particles B in a medium that does not dissolve using a laser scattering particle size distribution analyzer (for example, “LA-920” manufactured by HORIBA). Can be defined as
　また、無機微粒子Ｂの形態としては、例えば、球状に近い形状を有していてもよく、板状または繊維状の形状を有していてもよいが、セパレータの耐短絡性を高める観点からは、板状の粒子や、一次粒子が凝集した二次粒子構造の粒子であることが好ましい。特に、セパレータの空孔率の向上の点からは、一次粒子が凝集した二次粒子構造の粒子であることがより好ましい。前記の板状粒子や二次粒子の代表的なものとしては、板状のアルミナや板状のベーマイト、二次粒子状のアルミナや二次粒子状のベーマイトなどが挙げられる。 Moreover, as a form of the inorganic fine particle B, for example, it may have a shape close to a sphere, and may have a plate shape or a fiber shape, but from the viewpoint of improving the short circuit resistance of the separator. In addition, it is preferably a plate-like particle or a particle having a secondary particle structure in which primary particles are aggregated. In particular, from the viewpoint of improving the porosity of the separator, particles having a secondary particle structure in which primary particles are aggregated are more preferable. Typical examples of the plate-like particles and secondary particles include plate-like alumina, plate-like boehmite, secondary particle-like alumina, and secondary particle-like boehmite.
　本発明のセパレータにおいて、樹脂Ａと無機微粒子Ｂとは、後述する繊維状物からなる多孔質基材を使用しない場合、これらがセパレータの主体をなしていることが好ましく、具体的には、樹脂Ａと無機微粒子Ｂとの合計体積が、セパレータを構成する成分の全体積（空孔部分を除いた体積）中、５０体積％以上であることが好ましく、７０体積％以上であることがより好ましく、１００体積％であってもよい。他方、本発明のセパレータに、後述する繊維状物からなる多孔質基材を使用する場合には、樹脂Ａと無機微粒子Ｂとの合計体積が、セパレータを構成する成分の全体積（空孔部分を除いた体積）中、２０体積％以上であることが好ましく、４０体積％以上であることがより好ましい。 In the separator of the present invention, when the resin A and the inorganic fine particles B do not use a porous substrate made of a fibrous material to be described later, it is preferable that these are the main components of the separator. The total volume of A and the inorganic fine particles B is preferably 50% by volume or more, and more preferably 70% by volume or more, in the total volume of components constituting the separator (volume excluding the void portion). 100 volume% may be sufficient. On the other hand, when a porous substrate made of a fibrous material to be described later is used for the separator of the present invention, the total volume of the resin A and the inorganic fine particles B is the total volume of components constituting the separator (hole portion) The volume is preferably 20% by volume or more, and more preferably 40% by volume or more.
　また、セパレータの強度や形状安定性を確保するために、繊維状物を樹脂Ａや無機微粒子Ｂと共に混在させてもよい。繊維状物としては、耐熱温度（目視観察の際に変形が認められない温度）が１５０℃以上であって、電気絶縁性を有しており、電気化学的に安定で、電気化学素子の有する非水電解質やセパレータ製造の際に使用する溶剤に安定であれば、特に材質に制限はない。なお、本発明でいう「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おり、アスペクト比は１０以上であることが好ましい。 Further, in order to ensure the strength and shape stability of the separator, a fibrous material may be mixed together with the resin A and the inorganic fine particles B. The fibrous material has a heat-resistant temperature (temperature at which no deformation is observed during visual observation) of 150 ° C. or more, has an electrical insulating property, is electrochemically stable, and has an electrochemical element. The material is not particularly limited as long as it is stable to the solvent used in the production of the non-aqueous electrolyte and the separator. The “fibrous material” in the present invention means an aspect ratio [length in the long direction / width in the direction perpendicular to the long direction (diameter)] of 4 or more, and the aspect ratio Is preferably 10 or more.
　繊維状物の具体的な構成材料としては、例えば、セルロースおよびその変成体（カルボキシメチルセルロース（ＣＭＣ）、ヒドロキシプロピルセルロース（ＨＰＣ）など）、ポリオレフィン（ポリプロピレン（ＰＰ）、プロピレンの共重合体など）、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、ジルコニア、シリカなどの無機酸化物；などを挙げることができ、これらの構成材料は２種以上を含有していても構わない。また、繊維状物は、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 examples of the constituent material of the fibrous material include, for example, cellulose and its modified products (carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), etc.), polyolefin (polypropylene (PP), propylene copolymer, etc.), Polyester (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), etc.), polyacrylonitrile (PAN), aramid, polyamideimide, polyimide and other resins; glass, alumina, zirconia, silica and other inorganic materials These constituent materials may contain 2 or more types. The fibrous material may contain various known additives (for example, an antioxidant in the case of a resin) as necessary.
　また、繊維状物の直径は、セパレータ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、シート状物を形成してセパレータの基材を構成する場合に、その強度が小さくなって取り扱いが困難となることがある。また、径が小さすぎると、セパレータ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、電気化学素子の負荷特性を低下させてしまうことがある。 Further, the diameter of the fibrous material may be equal to or less than the thickness of the separator, but is preferably 0.01 to 5 μm, for example. When the diameter is too large, the entanglement between the fibrous materials is insufficient, and when the base material of the separator is formed by forming a sheet-like material, the strength may be reduced and handling may be difficult. On the other hand, if the diameter is too small, the pores of the separator become too small, and the ion permeability tends to decrease, which may reduce the load characteristics of the electrochemical element.
　セパレータにおける繊維状物の含有量は、全構成成分中、例えば、１０体積％以上であることが好ましく、２０体積％以上であることがより好ましい。なお、セパレータにおける繊維状物の含有量は、７０体積％以下であることが好ましく、６０体積％以下であることが好ましいが、後述する多孔質基材として使用する場合には、９０体積％以下であることが好ましく、８０体積％以下であることがより好ましい。 The content of the fibrous material in the separator is, for example, preferably 10% by volume or more, and more preferably 20% by volume or more, among all the constituent components. In addition, the content of the fibrous material in the separator is preferably 70% by volume or less, and preferably 60% by volume or less, but when used as a porous substrate described later, 90% by volume or less. It is preferable that it is 80 volume% or less.
　セパレータ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、セパレータ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 separator is, for example, that the angle of the long axis (long axis) with respect to the separator surface is preferably 30 ° or less on average, and more preferably 20 ° or less. .
　本発明のセパレータは、使用される電気化学素子の安全性を更に高める観点から、シャットダウン機能を有していることが好ましい。セパレータにシャットダウン機能を付与するには、例えば、融点が８０℃以上１４０℃以下の熱可塑性樹脂（以下、「熱溶融性樹脂Ｃ」という。）を含有させるか、または、加熱により液状の非水電解質（非水電解液。以下「電解液」と省略する場合がある。）を吸収して膨潤し且つ温度上昇と共に膨潤度が増大する樹脂（以下、「熱膨潤性樹脂Ｄ」という。）を含有させることが挙げられる。前記の方法によりシャットダウン機能を持たせたセパレータでは、電気化学素子内が発熱した際に、熱溶融性樹脂Ｃが溶融してセパレータの空孔を塞いだり、熱膨潤性樹脂Ｄが電気化学素子内の非水電解液を吸収したりして、電気化学反応の進行を抑制するシャットダウンを生じる。 The separator of the present invention preferably has a shutdown function from the viewpoint of further enhancing the safety of the electrochemical element used. In order to impart a shutdown function to the separator, for example, a thermoplastic resin having a melting point of 80 ° C. or higher and 140 ° C. or lower (hereinafter referred to as “hot-meltable resin C”) is contained, or liquid non-aqueous by heating. A resin (hereinafter referred to as “thermally swellable resin D”) that absorbs an electrolyte (non-aqueous electrolyte; hereinafter sometimes abbreviated as “electrolyte”) and swells and increases in degree of swelling as the temperature rises. It can be included. In the separator having the shutdown function by the above method, when the inside of the electrochemical element generates heat, the hot-melt resin C melts and closes the pores of the separator, or the heat-swellable resin D is inside the electrochemical element. The non-aqueous electrolyte is absorbed to cause a shutdown that suppresses the progress of the electrochemical reaction.
　熱溶融性樹脂Ｃとしては、融点、すなわちＪＩＳ　Ｋ　７１２１の規定に準じて、ＤＳＣを用いて測定される融解温度が８０℃以上１４０℃以下の樹脂であり、融解温度が１２０℃以上であることがより好ましく、電気絶縁性を有しており、電気化学素子の有する非水電解質やセパレータ製造の際に使用する溶剤に対して安定であり、更に、電気化学素子の作動電圧範囲において酸化還元されにくい電気化学的に安定な材料が好ましい。具体的には、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）、共重合ポリオレフィン、ポリオレフィン誘導体（塩素化ポリエチレンなど）、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－プロピレン共重合体、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やエチレン－エチルアクリレート共重合体などのエチレン－アクリル酸共重合体が例示できる。前記共重合ポリオレフィンにおけるエチレン由来の構造単位は、８５モル％以上であることが望ましい。また、ポリシクロオレフィンなどを用いることもできる。熱溶融性樹脂Ｃには、前記例示の樹脂を１種単独で用いてもよく、２種以上を用いても構わない。 The heat-meltable resin C is a resin having a melting point, that is, a melting temperature measured using DSC of 80 ° C. or higher and 140 ° C. or lower in accordance with JIS K 7121, and a melting temperature of 120 ° C. or higher. More preferably, it has electrical insulation properties, is stable to the non-aqueous electrolyte of the electrochemical element and the solvent used in the production of the separator, and is oxidized and reduced within the operating voltage range of the electrochemical element. A difficult electrochemically stable material is preferred. Specific examples include polyethylene (PE), polypropylene (PP), copolymerized polyolefin, polyolefin derivatives (such as chlorinated polyethylene), polyolefin wax, petroleum wax, and carnauba wax. Examples of the copolymer polyolefin include an ethylene-vinyl monomer copolymer, more specifically, an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer, and ethylene-ethyl. An ethylene-acrylic acid copolymer such as an acrylate copolymer can be exemplified. The structural unit derived from ethylene in the copolymerized polyolefin is desirably 85 mol% or more. Moreover, polycycloolefin etc. can also be used. As the heat-meltable resin C, the above exemplified resins may be used alone or in combination of two or more.
　熱溶融性樹脂Ｃとしては、前記例示の材料の中でも、ＰＥ、ポリオレフィンワックス、ＰＰ、またはエチレン由来の構造単位が８５モル％以上のＥＶＡが好適に用いられる。また、熱溶融性樹脂Ｃは、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。 As the heat-meltable resin C, among the materials exemplified above, PE, polyolefin wax, PP, or EVA having a structural unit derived from ethylene of 85 mol% or more is suitably used. Moreover, the heat-meltable resin C may contain various known additives (for example, antioxidants) added to the resin as necessary.
　熱膨潤性樹脂Ｄとしては、通常、電池が使用される温度領域（およそ７０℃以下）では、電解液を吸収しないか、または吸収量が限られており、従って膨潤の度合いが一定以下であるが、必要となる温度（Ｔｃ）まで加熱されたときには、電解液を吸収して大きく膨潤し且つ温度上昇と共に膨潤度が増大するような性質を有する樹脂が用いられる。熱膨潤性樹脂Ｄを含有するセパレータを用いた電気化学素子では、Ｔｃより低温側においては、熱膨潤性樹脂Ｄに吸収されない流動可能な電解液がセパレータの空孔内に存在するため、セパレータ内部のＬｉ（リチウム）イオンの伝導性が高くなり、良好な負荷特性を有する電気化学素子となるが、温度上昇に伴って膨潤度が増大する性質（以下、「熱膨潤性」という場合がある。）が現れる温度以上に加熱された場合には、熱膨潤性樹脂Ｄは電気化学素子内の電解液を吸収して大きく膨潤し、膨潤した熱膨潤性樹脂Ｄがセパレータの空孔を塞ぐと共に、流動可能な電解液が減少して電気化学素子が液枯れ状態となることにより、電解液と活物質との反応性を抑制し電気化学素子の安全性がより高められる。しかも、Ｔｃを超える高温となった場合、熱膨潤性により前記液枯れが更に進行し、電池の反応が更に抑制されることになるため、高温での安全性を更に高めることもできる。 As the heat-swellable resin D, in the temperature range (approximately 70 ° C. or lower) in which the battery is normally used, the electrolytic solution is not absorbed or the amount of absorption is limited, and thus the degree of swelling is below a certain level. However, when heated to the required temperature (Tc), a resin having such a property that it absorbs the electrolyte and swells greatly and the degree of swelling increases as the temperature rises is used. In an electrochemical device using a separator containing the heat-swellable resin D, a flowable electrolyte solution that is not absorbed by the heat-swellable resin D exists in the pores of the separator at a temperature lower than Tc. However, there is a case where the degree of swelling increases with increasing temperature (hereinafter referred to as “thermal swelling”). ), The heat-swellable resin D absorbs the electrolytic solution in the electrochemical element and swells greatly, and the swollen heat-swellable resin D closes the pores of the separator, By reducing the flowable electrolytic solution and causing the electrochemical element to wither, the reactivity between the electrolytic solution and the active material is suppressed, and the safety of the electrochemical device is further enhanced. In addition, when the temperature is higher than Tc, the liquid withering further proceeds due to thermal swellability, and the reaction of the battery is further suppressed, so that safety at high temperatures can be further enhanced.
　熱膨潤性樹脂Ｄが熱膨潤性を示し始める温度は、７５℃以上であることが好ましい。熱膨潤性樹脂Ｄが熱膨潤性を示し始める温度を７５℃以上とすることにより、Ｌｉイオンの伝導性が著しく減少して電気化学素子の内部抵抗が上昇する温度（Ｔｃ）を、およそ８０℃以上に設定することができるからである。一方、熱膨潤性を示す温度の下限が高くなるほど、セパレータのＴｃが高くなるので、Ｔｃをおよそ１３０℃以下に設定するために、熱膨潤性樹脂Ｄの熱膨潤性を示し始める温度は、１２５℃以下とすることが好ましく、１１５℃以下とすることがより好ましい。熱膨潤性を示す温度が高すぎると、電気化学素子内の活物質の異常発熱反応を十分に抑制できず、電気化学素子の安全性向上効果が十分に確保できないことがあり、また、熱膨潤性を示す温度が低すぎると、通常の電気化学素子の使用温度域（およそ７０℃以下）におけるＬｉイオンの伝導性が低くなりすぎることがある。 The temperature at which the heat-swellable resin D starts to show heat-swellability is preferably 75 ° C. or higher. By setting the temperature at which the heat-swellable resin D starts to exhibit heat-swellability to 75 ° C. or higher, the temperature (Tc) at which the internal resistance of the electrochemical element is increased by remarkably reducing the Li ion conductivity is about 80 ° C. This is because it can be set as described above. On the other hand, since the Tc of the separator increases as the lower limit of the temperature exhibiting thermal swellability increases, the temperature at which the thermal swellable resin D starts to exhibit thermal swellability in order to set Tc to about 130 ° C. or lower is 125 ° C. It is preferable to set it as ℃ or less, and it is more preferable to set as 115 ℃ or less. If the temperature showing the thermal swellability is too high, the abnormal exothermic reaction of the active material in the electrochemical element may not be sufficiently suppressed, and the effect of improving the safety of the electrochemical element may not be sufficiently secured. When the temperature showing the property is too low, the conductivity of Li ions may be too low in the temperature range (about 70 ° C. or lower) of a normal electrochemical device.
　また、熱膨潤性を示す温度より低い温度では、熱膨潤性樹脂Ｄは電解液をできるだけ吸収せず、膨潤が少ない方が望ましい。これは、電気化学素子の使用温度領域、例えば室温では、電解液は、熱膨潤性樹脂Ｄに取り込まれるよりもセパレータの空孔内に流動可能な状態で保持される方が、電気化学素子の負荷特性などの特性が良好になるからである。 Further, at a temperature lower than the temperature showing the heat swellability, it is desirable that the heat swellable resin D does not absorb the electrolyte solution as much as possible and has less swelling. This is because in an operating temperature range of an electrochemical element, for example, room temperature, the electrolyte is more likely to be held in a state where it can flow into the pores of the separator than to be taken into the heat-swellable resin D. This is because characteristics such as load characteristics are improved.
　常温（２５℃）において熱膨潤性樹脂Ｄが吸収する電解液量は、熱膨潤性樹脂Ｄの体積変化を表す下記式（１）で定義される膨潤度ＢＲにより評価することができる。 Electrolyte volume heat swelling resin D is absorbed at room temperature (25 ° C.) can be evaluated by the degree of swelling B R defined by the following equation represents the volume change of the thermal swelling resin D (1).
　ＢＲ＝（Ｖ０／Ｖｉ）－１　　　　　　　　　　　　　　（１）
　前記式（１）中、Ｖ０は、電解液中に２５℃で２４時間浸漬後の熱膨潤性樹脂Ｄの体積（ｃｍ３）、Ｖｉは、電解液に浸漬する前の熱膨潤性樹脂Ｄの体積（ｃｍ３）をそれぞれ表す。 B R = (V 0 / V i ) -1 (1)
In the formula (1), V 0 is the volume of the heat swelling resin D after 24 hours immersion at 25 ° C. in the electrolytic solution (cm 3), V i is the thermal swelling resin before immersion in electrolyte solution Each represents the volume (cm 3 ) of D.
　本発明のセパレータに熱膨潤性樹脂Ｄを使用する場合では、常温（２５℃）における熱膨潤性樹脂Ｄの膨潤度ＢＲは、１以下であることが好ましく、電解液の吸収による膨潤が小さいこと、すなわち、ＢＲはできるだけ０に近い小さな値となることが望まれる。また、熱膨潤性を示す温度より低温側では、膨潤度の温度変化ができるだけ小さくなるものが望ましい。 In the case of using the thermal swelling resin D to the separator of the present invention, the swelling degree B R of the heat-swellable resin D at room temperature (25 ° C.) is preferably 1 or less, it is less swelling due to absorption of the electrolyte solution it, i.e., B R it is desirable that the smallest possible value close to 0. Further, it is desirable that the temperature change of the degree of swelling is as small as possible on the lower temperature side than the temperature exhibiting thermal swellability.
　その一方で、熱膨潤性樹脂Ｄとしては、熱膨潤性を示す温度の下限以上に加熱された時は、電解液の吸収量が大きくなり、熱膨潤性を示す温度範囲において、温度と共に膨潤度が増大するものが用いられる。例えば、１２０℃において測定される、下記式（２）で定義される膨潤度ＢＴが、１以上であるものが好ましく用いられる。 On the other hand, as the heat-swellable resin D, when the heat-swellable resin D is heated to a temperature lower than the lower limit of the heat-swellable property, the amount of electrolyte absorbed increases, and in the temperature range showing the heat-swellability, Are used that increase. For example, it is measured at 120 ° C., swelling degree B T which is defined by the following formula (2) is, as 1 or higher is preferably used.
　ＢＴ＝（Ｖ１／Ｖ０）－１　　　　　　　　　　　　　　　（２）
　前記式（２）中、Ｖ０は、電解液中に２５℃で２４時間浸漬後の熱膨潤性樹脂Ｄの体積（ｃｍ３）、Ｖ１は、電解液中に２５℃で２４時間浸漬後、電解液を１２０℃に昇温させ、１２０℃で１時間経過後における熱膨潤性樹脂Ｄの体積（ｃｍ３）をそれぞれ表す。 B T = (V 1 / V 0 ) −1 (2)
In the formula (2), V 0 is the volume (cm 3 ) of the heat-swellable resin D after being immersed in an electrolytic solution at 25 ° C. for 24 hours, and V 1 is after being immersed in the electrolytic solution at 25 ° C. for 24 hours. The electrolyte solution is heated to 120 ° C., and the volume (cm 3 ) of the heat-swellable resin D after 1 hour at 120 ° C. is shown.
　一方、前記式（２）で定義される熱膨潤性樹脂Ｄの膨潤度は、大きくなりすぎると電気化学素子の変形を発生させることもあるため、１０以下であることが望ましい。 On the other hand, the degree of swelling of the heat-swellable resin D defined by the above formula (2) may be 10 or less because it may cause deformation of the electrochemical element if it becomes too large.
　前記式（２）で定義される膨潤度は、熱膨潤性樹脂Ｄの大きさの変化を、光散乱法やＣＣＤカメラなどにより撮影された画像の画像解析といった方法を用いて、直接測定することにより見積もることができるが、例えば以下の方法を用いてより正確に測定することができる。 The degree of swelling defined by the above formula (2) is to directly measure the change in the size of the heat-swellable resin D using a method such as light scattering or image analysis of an image taken with a CCD camera. However, it can be measured more accurately using, for example, the following method.
　前記式（１）および式（２）と同様に定義される、２５℃および１２０℃における膨潤度が既知のバインダ樹脂を用い、その溶液またはエマルジョンに、熱膨潤性樹脂Ｄを混合してスラリーを調製し、これをＰＥＴシートやガラス板などの基材上に塗布してフィルムを作製し、その質量を測定する。次に、このフィルムを、２５℃の電解液中に２４時間浸漬して質量を測定し、更に、電解液を１２０℃に加熱昇温させ、１２０℃で１時間保持後における質量を測定し、下記式（３）～（９）によって膨潤度ＢＴを算出する。なお、下記式（３）～（９）では、２５℃から１２０℃まで昇温した際の、電解液以外の成分の体積増加は無視できるものとする。 A binder resin having a known degree of swelling at 25 ° C. and 120 ° C., which is defined in the same manner as in the above formulas (1) and (2), is mixed with the heat-swellable resin D in the solution or emulsion to form a slurry. It is prepared and applied onto a substrate such as a PET sheet or glass plate to produce a film, and its mass is measured. Next, the film was immersed in an electrolyte at 25 ° C. for 24 hours to measure the mass, and the electrolyte was heated to 120 ° C., and the mass after holding at 120 ° C. for 1 hour was measured. formula by (3) to (9) for calculating the swelling degree B T. In the following formulas (3) to (9), the volume increase of components other than the electrolytic solution when the temperature is raised from 25 ° C. to 120 ° C. can be ignored.
　Ｖｉ＝Ｍｉ×Ｗ／ＰＡ　　　　　　　　　　　　　　　　　　（３）
　ＶＢ＝（Ｍ０－Ｍｉ）／ＰＢ　　　　　　　　　　　　　　  （４）
　ＶＣ＝Ｍ１／ＰＣ－Ｍ０／ＰＢ　　　　　　　　　　　　　　 （５）
　ＶＶ＝Ｍｉ×（１－Ｗ）／ＰＶ　　　　　　　　　　　　　  （６）
　Ｖ０＝Ｖｉ＋ＶＢ－ＶＶ×（ＢＢ＋１）　　　　　　　　　　 （７）
　ＶＤ＝ＶＶ×（ＢＢ＋１）　　　　　　　　　　　　　　　  （８）
　ＢＴ＝｛Ｖ０＋ＶＣ－ＶＤ×（ＢＣ＋１）｝／Ｖ０－１　　　  （９） V i = M i × W / P A (3)
V B = (M 0 −M i ) / P B (4)
V C = M 1 / P C −M 0 / P B (5)
V V = M i × (1−W) / P V (6)
V 0 = V i + V B −V V × (B B +1) (7)
V D = V V × (B B +1) (8)
B T = {V 0 + V C −V D × (B C +1)} / V 0 −1 (9)
　ここで、前記式（３）～（９）中、
Ｖｉ：電解液に浸漬する前の熱膨潤性樹脂Ｄの体積（ｃｍ３）、
Ｖ０：電解液中に常温で２４時間浸漬後の熱膨潤性樹脂Ｄの体積（ｃｍ３）、
ＶＢ：電解液中に常温で２４時間浸漬後に、フィルムに吸収された電解液の体積（ｃｍ３）、
ＶＣ：電解液中に常温で２４時間浸漬した時点から、電解液を１２０℃まで昇温させ、更に１２０℃で１時間経過するまでの間に、フィルムに吸収された電解液の体積（ｃｍ３）、
ＶＶ：電解液に浸漬する前のバインダ樹脂の体積（ｃｍ３）、
ＶＤ：電解液中に常温で２４時間浸漬後のバインダ樹脂の体積（ｃｍ３）、
Ｍｉ：電解液に浸漬する前のフィルムの質量（ｇ）、
Ｍ０：電解液中に常温で２４時間浸漬後のフィルムの質量（ｇ）、
Ｍ１：電解液中に常温で２４時間浸漬した後、電解液を１２０℃まで昇温させ、更に１２０℃で１時間経過した後におけるフィルムの質量（ｇ）、
Ｗ：電解液に浸漬する前のフィルム中の熱膨潤性樹脂Ｄの質量比率、
ＰＡ：電解液に浸漬する前の熱膨潤性樹脂Ｄの比重（ｇ／ｃｍ３）、
ＰＢ：常温における電解液の比重（ｇ／ｃｍ３）、
ＰＣ：所定温度での電解液の比重（ｇ／ｃｍ３）、
ＰＶ：電解液に浸漬する前のバインダ樹脂の比重（ｇ／ｃｍ３）、
ＢＢ：電解液中に常温で２４時間浸漬後のバインダ樹脂の膨潤度、
ＢＣ：前記式（２）で定義される昇温時のバインダ樹脂の膨潤度
である。 Here, in the formulas (3) to (9),
V i : Volume (cm 3 ) of the heat-swellable resin D before being immersed in the electrolytic solution,
V 0 : volume (cm 3 ) of the heat-swellable resin D after being immersed in the electrolyte at room temperature for 24 hours,
V B : volume of the electrolyte solution (cm 3 ) absorbed in the film after being immersed in the electrolyte solution at room temperature for 24 hours,
V C : The volume of the electrolyte solution absorbed by the film (cm) during the period from when it was immersed in the electrolyte solution at room temperature for 24 hours until the electrolyte solution was heated to 120 ° C. and further passed at 120 ° C. for 1 hour. 3 ),
V V : volume (cm 3 ) of the binder resin before being immersed in the electrolytic solution,
V D : volume of the binder resin (cm 3 ) after being immersed in the electrolytic solution at room temperature for 24 hours,
M i : mass (g) of the film before being immersed in the electrolytic solution,
M 0 : mass (g) of the film after being immersed in the electrolytic solution at room temperature for 24 hours,
M 1 : After immersing in the electrolytic solution at room temperature for 24 hours, the temperature of the electrolytic solution was raised to 120 ° C., and the mass (g) of the film after 1 hour at 120 ° C.
W: Mass ratio of the heat-swellable resin D in the film before being immersed in the electrolytic solution,
P A : specific gravity (g / cm 3 ) of the heat-swellable resin D before being immersed in the electrolytic solution,
P B : Specific gravity of electrolyte at room temperature (g / cm 3 ),
P C: specific gravity of the electrolyte at a predetermined temperature (g / cm 3),
P V : Specific gravity (g / cm 3 ) of the binder resin before being immersed in the electrolytic solution,
B B : degree of swelling of the binder resin after being immersed in the electrolyte at room temperature for 24 hours,
B C is the degree of swelling of the binder resin at the time of temperature increase defined by the above formula (2).
　また、前記の方法により前記式（３）および前記式（７）から求められるＶｉおよびＶ０から、前記式（１）を用いて常温での膨潤度ＢＲを求めることができる。 Also, the V i and V 0 is determined from the said equation by the method (3) and the formula (7), can be determined swelling degree B R at room temperature using the above formula (1).
　なお、本発明の電気化学素子は、従来から知られている電気化学素子と同様に、例えば、リチウム塩を有機溶剤に溶解した溶液が非水電解質として使用される（リチウム塩や有機溶剤の種類、リチウム塩濃度などの詳細は後述する。）。よって、熱膨潤性樹脂Ｄとしては、リチウム塩の有機溶剤溶液中で、７５～１２５℃のいずれかの温度に達した時に前記の熱膨潤性を示し始め、好ましくは該溶液中において膨潤度ＢＲおよびＢＴが前記の値を満足するように膨潤し得るものが推奨される。 In addition, the electrochemical element of the present invention uses, for example, a solution obtained by dissolving a lithium salt in an organic solvent as a nonaqueous electrolyte, as in the case of conventionally known electrochemical elements (types of lithium salt and organic solvent). Details of the lithium salt concentration will be described later). Therefore, the heat-swellable resin D starts to show the above-mentioned heat-swellability when it reaches any temperature of 75 to 125 ° C. in an organic solvent solution of lithium salt. It is recommended that R and B T can swell so as to satisfy the above values.
　熱膨潤性樹脂Ｄとしては、耐熱性および電気絶縁性を有しており、電解液に対して安定であり、更に、電池の作動電圧範囲において酸化還元されにくい電気化学的に安定な材料が好ましく、そのような材料としては、例えば、樹脂架橋体が挙げられる。より具体的には、スチレン樹脂〔ポリスチレン（ＰＳ）など〕、スチレンブタジエンゴム（ＳＢＲ）、アクリル樹脂〔ポリメチルメタクリレート（ＰＭＭＡ）など〕、ポリアルキレンオキシド〔ポリエチレンオキシド（ＰＥＯ）など〕、フッ素樹脂〔ポリフッ化ビニリデン（ＰＶＤＦ）など〕およびこれらの誘導体よりなる群から選ばれる少なくとも１種の樹脂の架橋体；尿素樹脂；ポリウレタン；などが例示できる。熱膨潤性樹脂Ｄには、前記例示の樹脂を１種単独で用いてもよく、２種以上を併用してもよい。また、熱膨潤性樹脂Ｄは、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。 The heat-swellable resin D is preferably an electrochemically stable material that has heat resistance and electrical insulation, is stable with respect to the electrolyte, and is not easily oxidized or reduced in the operating voltage range of the battery. Examples of such a material include a crosslinked resin. More specifically, styrene resin (polystyrene (PS), etc.), styrene butadiene rubber (SBR), acrylic resin (polymethyl methacrylate (PMMA), etc.), polyalkylene oxide (polyethylene oxide (PEO), etc.), fluororesin [ Polyvinylidene fluoride (PVDF) and the like] and a crosslinked product of at least one resin selected from the group consisting of these derivatives; urea resin; polyurethane; and the like. For the heat-swellable resin D, the above exemplified resins may be used alone or in combination of two or more. Moreover, the heat-swellable resin D may contain various known additives that are added to the resin, for example, an antioxidant, as necessary.
　前記の構成材料の中でも、スチレン樹脂架橋体、アクリル樹脂架橋体およびフッ素樹脂架橋体が好ましく、架橋ＰＭＭＡが特に好ましく用いられる。 Among the above-described constituent materials, a crosslinked styrene resin, a crosslinked acrylic resin, and a crosslinked fluororesin are preferable, and crosslinked PMMA is particularly preferably used.
　これら樹脂架橋体が、温度上昇により電解液を吸収して膨潤するメカニズムについては明らかでないが、ガラス転移温度（Ｔｇ）との相関が考えられる。すなわち、樹脂は、一般にそのＴｇまで加熱されたときに柔軟になるため、前記のような樹脂は、Ｔｇ以上の温度で多くの電解液の吸収が可能となり膨潤するのではないかと推定される。従って、熱膨潤性樹脂Ｄとしては、実際にシャットダウン作用が生じる温度が熱膨潤性樹脂Ｄの熱膨潤性を示し始める温度より多少高くなることを考慮し、およそ７５～１２５℃にＴｇを有する樹脂架橋体を用いることが望ましいと考えられる。なお、本明細書でいう熱膨潤性樹脂Ｄである樹脂架橋体のＴｇは、ＪＩＳ　Ｋ　７１２１の規定に準じて、ＤＳＣを用いて測定される値である。 Although the mechanism by which these resin crosslinked bodies swell by absorbing the electrolyte solution due to temperature rise is not clear, a correlation with the glass transition temperature (Tg) is considered. That is, since the resin generally becomes flexible when heated to its Tg, it is estimated that the resin as described above can absorb a large amount of electrolyte at a temperature equal to or higher than Tg and swell. Accordingly, the heat-swellable resin D is a resin having a Tg of about 75 to 125 ° C., considering that the temperature at which the shutdown action actually occurs is somewhat higher than the temperature at which the heat-swellable resin D starts to exhibit heat-swellability. It is considered desirable to use a crosslinked body. In addition, Tg of the resin crosslinked body which is the heat-swellable resin D in this specification is a value measured using DSC in accordance with the provisions of JIS K7121.
　前記樹脂架橋体では、電解液を含む前の所謂乾燥状態においては、温度上昇により膨張しても、温度を下げることにより再び収縮するというように、温度変化に伴う体積変化にある程度可逆性があり、また、熱膨潤性を示す温度よりもかなり高い耐熱温度を有するため、熱膨潤性を示す温度の下限が１００℃くらいであっても、２００℃またはそれ以上まで加熱することが可能な材料を選択することができる。そのため、セパレータの作製工程などで加熱を行っても、樹脂が溶解したり樹脂の熱膨潤性が損なわれたりすることがなく、一般の加熱プロセスを含む製造工程での取り扱いが容易となる。 In the so-called dry state before the electrolyte solution is included in the resin crosslinked body, the volume change accompanying the temperature change is reversible to some extent so that even if it expands due to the temperature rise, it shrinks again when the temperature is lowered. In addition, since it has a heat-resistant temperature that is considerably higher than the temperature that exhibits thermal swellability, even if the lower limit of the temperature that exhibits thermal swellability is about 100 ° C, a material that can be heated to 200 ° C or higher is used. You can choose. Therefore, even when heating is performed in a separator manufacturing process or the like, the resin is not dissolved or the thermal swellability of the resin is not impaired, and handling in a manufacturing process including a general heating process becomes easy.
　熱溶融性樹脂Ｃや熱膨潤性樹脂Ｄ（以下、熱溶融性樹脂Ｃと熱膨潤性樹脂Ｄとを纏めて「シャットダウン樹脂」という場合がある。）の形態は特に限定はされないが、微粒子の形状のものを用いることが好ましく、その大きさは、乾燥時における粒径がセパレータの厚みより小さければよく、セパレータの厚みの１／１００～１／３の平均粒径を有することが好ましく、具体的には、平均粒径が０．１～２０μｍであることが好ましい。シャットダウン樹脂粒子の粒径が小さすぎる場合は、粒子同士の隙間が小さくなり、イオンの伝導パスが長くなって電気化学素子の特性が低下する虞がある。また、シャットダウン樹脂粒子の粒径が大きすぎると、隙間が大きくなってリチウムデンドライトなどに起因する短絡に対する耐性の向上効果が小さくなる虞がある。なお、シャットダウン樹脂粒子の平均粒径は、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、シャットダウン樹脂を膨潤させない媒体（例えば水）に当該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。 The form of the heat-meltable resin C or the heat-swellable resin D (hereinafter, the heat-meltable resin C and the heat-swellable resin D may be collectively referred to as “shutdown resin”) is not particularly limited. It is preferable to use a shape having a particle diameter at the time of drying smaller than the thickness of the separator, and preferably has an average particle diameter of 1/100 to 1/3 of the thickness of the separator. Specifically, the average particle diameter is preferably 0.1 to 20 μm. When the particle diameter of the shutdown resin particles is too small, the gap between the particles becomes small, the ion conduction path becomes long, and the characteristics of the electrochemical device may be deteriorated. Moreover, when the particle diameter of the shutdown resin particles is too large, there is a possibility that the effect of improving the resistance to short circuit caused by lithium dendrite or the like becomes small because the gap becomes large. The average particle diameter of the shutdown resin particles is determined by, for example, using a laser scattering particle size distribution analyzer (for example, “LA-920” manufactured by HORIBA) and dispersing the fine particles in a medium that does not swell the shutdown resin (for example, water). It can prescribe | regulate as a measured number average particle diameter.
　また、シャットダウン樹脂は、前記以外の形態であってもよく、他の構成要素、例えば、無機微粒子や繊維状物の表面に積層され一体化された状態で存在していてもよい。具体的に、無機微粒子をコアとしシャットダウン樹脂をシェルとするコアシェル構造の粒子として存在してもよく、また、芯材の表面にシャットダウン樹脂を有する複層構造の繊維であってもよい。更に、セパレータの片面または両面に、シャットダウン樹脂を含む層（シャットダウン樹脂のみで形成された層や、シャットダウン樹脂とバインダとを含む層など）を形成することで、セパレータにシャットダウン樹脂を持たせてもよい。 Further, the shutdown resin may be in a form other than the above, and may be present in a state of being laminated and integrated on the surface of another constituent element, for example, inorganic fine particles or a fibrous material. Specifically, it may exist as core-shell structured particles having inorganic fine particles as a core and a shutdown resin as a shell, or may be a multi-layered fiber having a shutdown resin on the surface of a core material. Furthermore, even if the separator is provided with a shutdown resin by forming a layer containing the shutdown resin (a layer formed only with the shutdown resin or a layer containing the shutdown resin and the binder) on one or both sides of the separator. Good.
　セパレータにおけるシャットダウン樹脂の含有量は、シャットダウンの効果をより得やすくするために、例えば、下記のようであることが好ましい。セパレータの全構成成分中におけるシャットダウン樹脂の体積は、１０体積％以上であることが好ましく、２０体積％以上であることがより好ましい。一方、セパレータの高温時における形状安定性確保の点から、セパレータの全構成成分中におけるシャットダウン樹脂の体積は、５０体積％以下であることが好ましく、４０体積％以下であることがより好ましい。 The content of the shutdown resin in the separator is preferably as follows, for example, in order to make it easier to obtain the shutdown effect. The volume of the shutdown resin in all the constituent components of the separator is preferably 10% by volume or more, and more preferably 20% by volume or more. On the other hand, the volume of the shutdown resin in all the constituent components of the separator is preferably 50% by volume or less, and more preferably 40% by volume or less, from the viewpoint of securing the shape stability at high temperatures of the separator.
　本発明のセパレータは、例えば、下記の（１）～（４）の方法により製造することができる。セパレータの製造方法（１）は、樹脂Ａを形成するためのモノマーやオリゴマー、光重合開始剤、並びに無機微粒子Ｂ、更には必要に応じて熱溶融性樹脂Ｃや熱膨潤性樹脂Ｄの粒子などを含み、これらを揮発性物質（揮発性の溶剤）に分散させた液状組成物（スラリーなど）を調製し（モノマーやオリゴマー、光重合開始剤は、揮発性物質中に溶解していてもよい）、この液状組成物を多孔質基材に塗布または含浸させ、光照射してセパレータ形成用のシートとした後、揮発性物質を所定の温度で乾燥により除去して空孔を形成する方法である。この場合の多孔質基材としては、具体的には、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を例示できる。 The separator of the present invention can be produced, for example, by the following methods (1) to (4). The manufacturing method (1) of the separator includes monomers and oligomers for forming the resin A, a photopolymerization initiator, inorganic fine particles B, and particles of a heat-meltable resin C and a heat-swellable resin D as necessary. And a liquid composition (slurry etc.) in which these are dispersed in a volatile substance (volatile solvent) is prepared (monomer, oligomer, photopolymerization initiator may be dissolved in the volatile substance) ), By applying or impregnating the liquid composition to a porous substrate, irradiating with light to form a separator-forming sheet, and then removing volatile substances by drying at a predetermined temperature to form pores. is there. Specifically, as the porous substrate in this case, a woven fabric composed of at least one kind of fibrous material containing the above-mentioned exemplified materials as constituent components, or a structure in which these fibrous materials are entangled with each other. Examples thereof include porous sheets such as non-woven fabrics. 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.
　前記液状組成物に使用する揮発性物質としては、モノマーやオリゴマー、光重合開始剤、無機微粒子Ｂなどを均一に分散したり溶解したりできるものが好ましく、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、一般に有機溶剤が好適に用いられる。なお、これらの溶剤に、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よい。また、水を揮発性物質に用いることもでき、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。 As the volatile substance used in the liquid composition, monomers and oligomers, photopolymerization initiators, those that can uniformly disperse or dissolve the inorganic fine particles B and the like are preferable, for example, aromatic hydrocarbons such as toluene, In general, organic solvents such as furans such as tetrahydrofuran and ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferably used. 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, water can be used as a volatile substance, and at this time, alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.) can be appropriately added to control the interfacial tension.
　また、光重合開始剤としては、例えば、２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシド、２，２－ジメトキシ－２－フェニルアセトフェノン、２－ヒドロキシ－２－メチルプロピオフェノンなどを使用することができる。光重合開始剤の使用量は、モノマーおよびオリゴマーの量１００質量部に対し、１～１０質量部とすることが好ましい。 As the photopolymerization initiator, for example, 2,4,6-trimethylbenzoylbisphenylphosphine oxide, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, etc. should be used. Can do. The amount of the photopolymerization initiator used is preferably 1 to 10 parts by mass with respect to 100 parts by mass of monomers and oligomers.
　前記液状組成物では、モノマーやオリゴマー、光重合開始剤、無機微粒子などを含む固形分含量を、例えば１０～５０質量％とすることが好ましい。 In the liquid composition, the solid content including monomers, oligomers, photopolymerization initiators, inorganic fine particles and the like is preferably 10 to 50% by mass, for example.
　本発明のセパレータの製造方法（２）は、樹脂Ａを形成するためのモノマーやオリゴマー、光重合開始剤、無機微粒子Ｂ、並びに、特定の溶剤Ｘに溶解し得る材料Ｍ（液状組成物の調製に使用する溶剤Ｙには溶解しない材料）、更には必要に応じて熱溶融性樹脂Ｃや熱膨潤性樹脂Ｄの粒子などを含み、これらを溶剤Ｙに分散させた液状組成物（スラリーなど）を調製し（モノマーやオリゴマー、光重合開始剤などは、溶剤Ｙに溶解していてもよい）、この液状組成物を多孔質基材に塗布または含浸させ、光照射してセパレータ形成用のシートとした後、前記材料Ｍを前記特定の溶剤Ｘで抽出して空孔を形成する方法である。 The separator production method (2) of the present invention comprises a monomer M or oligomer for forming the resin A, a photopolymerization initiator, inorganic fine particles B, and a material M that can be dissolved in a specific solvent X (preparation of a liquid composition). A material that does not dissolve in the solvent Y used in the above), and a liquid composition (slurry or the like) in which particles of a heat-meltable resin C or a heat-swellable resin D are dispersed in the solvent Y if necessary. (Monomers, oligomers, photopolymerization initiators and the like may be dissolved in solvent Y), and this liquid composition is coated or impregnated on a porous substrate and irradiated with light to form a sheet for forming a separator. Then, the material M is extracted with the specific solvent X to form pores.
　溶剤Ｘとしては、例えば、エチルメチルカーボネート、ジエチルカーボネート、ジメチルカーボネート、プロピレンカーボネート、テトラヒドロフラン、ε－カプロラクトン等を使用できる。 As the solvent X, for example, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, tetrahydrofuran, ε-caprolactone and the like can be used.
　前記の特定の溶剤Ｘに溶解し得る材料Ｍとしては、例えば、ポリオレフィン樹脂、ポリウレタン樹脂、アクリル樹脂などを用いることができる。これらの材料は、例えば粒子状のものを用いることが好ましいが、そのサイズや使用量は、セパレータに要求される空孔率や孔径に応じて調整することができる。通常は、前記材料の平均粒径（無機微粒子Ｂの平均粒径と同じ方法で測定される平均粒径）が０．１～２０μｍであることが好ましく、また、使用量は、前記液状組成物における全固形分のうち、１～１０質量％とすることが好ましい。 As the material M that can be dissolved in the specific solvent X, for example, polyolefin resin, polyurethane resin, acrylic resin, or the like can be used. These materials are preferably used in the form of particles, for example, but the size and amount of use can be adjusted according to the porosity and pore size required for the separator. Usually, the average particle size of the material (average particle size measured by the same method as the average particle size of the inorganic fine particles B) is preferably 0.1 to 20 μm, and the amount used is the liquid composition The total solid content in is preferably 1 to 10% by mass.
　製造方法（２）に係る前記液状組成物における溶剤Ｙには、製造方法（１）に係る液状組成物に使用し得る揮発性物質と同じものが使用できる。また、製造方法（２）に係る前記液状組成物の固形分含量は、製造方法（１）の場合と同様に、例えば１０～５０質量％とすることが好ましい。また、製造方法（２）に係る前記液状組成物には、製造方法（１）の場合と同様の材料を使用して、界面張力を制御することもできる。 For the solvent Y in the liquid composition according to the production method (2), the same volatile substances that can be used in the liquid composition according to the production method (1) can be used. Further, the solid content of the liquid composition according to the production method (2) is preferably, for example, 10 to 50% by mass, as in the case of the production method (1). Further, the liquid composition according to the production method (2) can be controlled by using the same material as in the production method (1) to control the interfacial tension.
　本発明のセパレータの製造方法（３）は、製造方法（１）に係る前記液状組成物と同じものを、フィルムや金属箔などの基材の上に塗布し、光照射してセパレータ形成用のシートとした後、揮発性物質を所定の温度で乾燥により除去して空孔を形成し、その後に基材から剥離する方法である。なお、製造方法（３）に係る液状組成物は、繊維状物を含有していてもよく、その繊維状物も含めた固形分量が、例えば１０～５０質量％であることが好ましい。 The separator production method (3) of the present invention is the same as the liquid composition according to the production method (1), which is applied on a substrate such as a film or metal foil, and irradiated with light to form a separator. In this method, after forming into a sheet, volatile substances are removed by drying at a predetermined temperature to form pores, and then peeled off from the substrate. The liquid composition according to the production method (3) may contain a fibrous material, and the solid content including the fibrous material is preferably, for example, 10 to 50% by mass.
　本発明のセパレータの製造方法（４）は、製造方法（２）に係る前記液状組成物と同じものを、フィルムや金属箔などの基材の上に塗布し、光照射してセパレータ形成用のシートとした後、前記材料Ｍを前記特定の溶剤Ｘで抽出して空孔を形成し、その後に基材から剥離する方法である。なお、製造方法（４）に係る液状組成物は、繊維状物を含有していてもよく、その繊維状物も含めた固形分量が、例えば１０～５０質量％であることが好ましい。 The separator manufacturing method (4) of the present invention is the same as the liquid composition according to the manufacturing method (2), applied on a substrate such as a film or metal foil, and irradiated with light to form a separator. After forming into a sheet, the material M is extracted with the specific solvent X to form pores, and then peeled off from the substrate. The liquid composition according to the production method (4) may contain a fibrous material, and the solid content including the fibrous material is preferably, for example, 10 to 50% by mass.
　また、製造方法（３）や製造方法（４）でセパレータを製造する場合に、電気化学素子に係る正極および負極のいずれか一方を基材とすることで、セパレータと電極とを一体化した構造としてもよい。この場合、セパレータは基材となる電極からは剥離させない。 Moreover, when manufacturing a separator by manufacturing method (3) or manufacturing method (4), the structure which integrated the separator and the electrode by using either the positive electrode which concerns on an electrochemical element, or a negative electrode as a base material It is good. In this case, the separator is not peeled off from the electrode serving as the base material.
　セパレータと電極とを一体化した構造では、電極の合剤層とセパレータとの密着性が高いため、セパレータが電極から剥がれることなく、電極同士を巻回あるいは積層することができる。また、柔軟性の高い樹脂Ａを用いているため、巻回体を用いる非水電解質二次電池の場合、巻回体の最内周のコーナー部での短絡を防ぐことができる。 In the structure in which the separator and the electrode are integrated, the adhesion between the electrode mixture layer and the separator is high, so that the electrodes can be wound or laminated without peeling the separator from the electrode. Moreover, since the highly flexible resin A is used, in the case of a non-aqueous electrolyte secondary battery using a wound body, it is possible to prevent a short circuit at the corner portion of the innermost periphery of the wound body.
　製造方法（１）～（４）において、光照射の条件は、一般的な光重合で採用されている条件とすればよい。具体的には、例えば、紫外光の光源として波長３６５ｎｍの高圧水銀ランプを使用し、照射強度６０ｍＷ／ｃｍ２で、１０秒間光照射するなどすればよい。なお、光照射に使用する光の波長、照射強度および照射時間などは適宜変更することができる。 In the production methods (1) to (4), the light irradiation conditions may be those employed in general photopolymerization. Specifically, for example, a high-pressure mercury lamp having a wavelength of 365 nm is used as an ultraviolet light source, and light irradiation is performed for 10 seconds at an irradiation intensity of 60 mW / cm 2 . In addition, the wavelength of the light used for light irradiation, irradiation intensity | strength, irradiation time, etc. can be changed suitably.
　セパレータの空孔率としては、乾燥した状態で、電解液の保液量を確保してイオン透過性を良好にするために、１０％以上であることが好ましい。一方、セパレータ強度の確保と内部短絡の防止の観点から、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い。なお、乾燥した状態でのセパレータの空孔率：Ｐ（％）は、セパレータの厚み、面積あたりの質量、構成成分の密度から、下記式（１０）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。 The porosity of the separator is preferably 10% or more in order to ensure a sufficient amount of electrolyte solution and improve ion permeability in a dry state. On the other hand, from the viewpoint of securing separator strength and preventing internal short circuit, the separator porosity is preferably 70% or less in a dry state. In addition, the porosity of the separator in a dry state: P (%) is obtained from the thickness of the separator, the mass per area, and the density of the constituent components by using the following formula (10) to obtain the sum for each component i. Can be calculated.
　Ｐ＝１００－（Σａｉ／ρｉ）×（ｍ／ｔ）　　　　　　　（１０）
　ここで、前記式中、ａｉ：質量％で表した成分ｉの比率、ρｉ：成分ｉの密度（ｇ／ｃｍ３）、ｍ：セパレータの単位面積あたりの質量（ｇ／ｃｍ２）、ｔ：乾燥した状態で測定したセパレータの厚み（ｃｍ）である。 P = 100− (Σa i / ρ i ) × (m / t) (10)
Here, in the above formula, a i : ratio of component i expressed by mass%, ρ i : density of component i (g / cm 3 ), m: mass per unit area of separator (g / cm 2 ), t: The thickness (cm) of the separator measured in a dry state.
　また、本発明のセパレータは、ＪＩＳ　Ｐ　８１１７に準拠した方法で行われ、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が、１０～３００ｓｅｃであることが望ましい。ガーレー値が大きすぎると、イオン透過性が小さくなり、他方、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。更に、セパレータの強度としては、直径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場合がある。前記の構成を採用することにより、前記のガーレー値や突き刺し強度を有するセパレータとすることができる。 In addition, the separator of the present invention is performed by a method according to JIS P 8117, and the 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 10 to 300 sec. It is desirable to be. If the Gurley value is too large, the ion permeability decreases, whereas if it is too small, the strength of the separator may decrease. Further, the strength of the separator is desirably 50 g or more in terms of piercing strength using a needle having a diameter of 1 mm. If the piercing strength is too small, a short circuit may occur due to the piercing of the separator when lithium dendrite crystals are generated. By employ | adopting the said structure, it can be set as the separator which has the said Gurley value and piercing strength.
　正極と負極とは独立してセパレータが存在する場合の本発明のセパレータの厚みは、正極と負極とをより確実に隔離する観点から、５μｍ以上が好ましく、６μｍ以上であることがより好ましく、１０μｍ以上であることが更に好ましい。他方、セパレータの厚みが大きすぎると、電池としたときのエネルギー密度が低下してしまうことがあるため、その厚みは、７０μｍ以下が好ましく、５０μｍ以下であることがより好ましく、３０μｍ以下であることが更に好ましい。なお、セパレータと電極とを一体化した構造の場合、セパレータの厚みとは、電極の一方の面に塗布されたセパレータの厚みを指す。 When the separator exists independently of the positive electrode and the negative electrode, the thickness of the separator of the present invention is preferably 5 μm or more, more preferably 6 μm or more, from the viewpoint of more reliably separating the positive electrode and the negative electrode. It is still more preferable that it is above. On the other hand, if the separator is too thick, the energy density of the battery may be reduced. Therefore, the thickness is preferably 70 μm or less, more preferably 50 μm or less, and 30 μm or less. Is more preferable. In the case of a structure in which the separator and the electrode are integrated, the thickness of the separator refers to the thickness of the separator applied to one surface of the electrode.
　本発明の電気化学素子は、非水電解質を有し、かつ前記本発明のセパレータを有していればよく、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電気化学素子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。 The electrochemical device of the present invention only needs to have a non-aqueous electrolyte and the separator of the present invention, and there are no particular restrictions on other configurations and structures, and conventionally known electrochemical devices Various configurations and structures adopted in the above can be applied.
　なお、本発明の電気化学素子は、非水電解質二次電池の他、非水電解質一次電池やスーパーキャパシタなどが含まれ、特に高温での安全性が要求される用途に好ましく適用できる。以下、本発明の電気化学素子が非水電解質二次電池である場合を中心に詳述する。 The electrochemical device of the present invention includes non-aqueous electrolyte secondary batteries, non-aqueous electrolyte primary batteries, supercapacitors, and the like, and can be preferably applied to applications that require safety at high temperatures. Hereinafter, the case where the electrochemical device of the present invention is a non-aqueous electrolyte secondary battery will be described in detail.
　非水電解質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 non-aqueous electrolyte secondary battery include a cylindrical shape (such as a square cylindrical 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.
　正極には、例えば、正極活物質、バインダおよび導電助剤などを含む正極合剤層を、集電体の片面または両面に有する構造のものが使用できる。 As the positive electrode, for example, one having a structure in which a positive electrode mixture layer containing a positive electrode active material, a binder, a conductive additive and the like is provided on one side or both sides of a current collector can be used.
　正極活物質としては、従来から知られている非水電解質二次電池に用いられているＬｉイオンを吸蔵・放出可能な材料を使用できる。例えば、Ｌｉ１＋ｘＭＯ２（－０．１＜ｘ＜０．１、Ｍ：Ｃｏ、Ｎｉ、Ｍｎ、Ａｌ、Ｍｇなど）で表される層状構造のリチウム含有遷移金属酸化物、ＬｉＭｎ２Ｏ４やその元素の一部を他元素で置換したスピネル構造のリチウムマンガン酸化物、ＬｉＭＰＯ４（Ｍ：Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅなど）で表されるオリビン型化合物などを用いることが可能である。前記層状構造のリチウム含有遷移金属酸化物の具体例としては、ＬｉＣｏＯ２やＬｉＮｉ１－ｘＣｏｘ－ｙＡｌｙＯ２（０．１≦ｘ≦０．３、０．０１≦ｙ≦０．２）などのほか、少なくともＣｏ、ＮｉおよびＭｎを含む酸化物（ＬｉＭｎ１／３Ｎｉ１／３Ｃｏ１／３Ｏ２、ＬｉＭｎ５／１２Ｎｉ５／１２Ｃｏ１／６Ｏ２、ＬｉＭｎ３／５Ｎｉ１／５Ｃｏ１／５Ｏ２など）などを例示することができる。 As a positive electrode active material, the material which can occlude / release Li ion used for the conventionally known nonaqueous electrolyte secondary battery can be used. For example, a lithium-containing transition metal oxide having a layered structure represented by Li 1 + x MO 2 (−0.1 <x <0.1, M: Co, Ni, Mn, Al, Mg, etc.), LiMn 2 O 4 , It is possible to use a spinel structure lithium manganese oxide in which a part of the element is substituted with another element, an olivine type compound represented by LiMPO 4 (M: Co, Ni, Mn, Fe, etc.), or the like. Specific examples of the lithium-containing transition metal oxide having a layered structure include LiCoO 2 and LiNi 1-x Co xy Al y O 2 (0.1 ≦ x ≦ 0.3, 0.01 ≦ y ≦ 0. 2) and other oxides containing at least Co, Ni and Mn (LiMn 1/3 Ni 1/3 Co 1/3 O 2 , LiMn 5/12 Ni 5/12 Co 1/6 O 2 , LiMn 3 / 5 Ni 1/5 Co 1/5 O 2 etc.).
　導電助剤としては、カーボンブラックなどの炭素材料が用いられ、バインダとしては、ＰＶＤＦなどのフッ素樹脂が用いられ、これらの材料と正極活物質とが混合された正極合剤により正極合剤層が、集電体上に形成される。 A carbon material such as carbon black is used as the conductive auxiliary agent, and a fluorine resin such as PVDF is used as the binder, and the positive electrode mixture layer is formed by a positive electrode mixture in which these materials and a positive electrode active material are mixed. , Formed on the current collector.
　また、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。 Further, 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. Usually, an aluminum foil having a thickness of 10 to 30 μm is 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.
　負極としては、従来から知られている非水電解質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・放出可能な負極活物質を含有する負極であれば特に制限はない。例えば、負極活物質として、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。負極としては、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）やバインダ（ＰＶＤＦなど）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、または、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積層したものなどが用いられる。 The negative electrode is not particularly limited as long as it is a negative electrode used in a conventionally known non-aqueous electrolyte secondary battery, that is, a negative electrode containing a negative electrode active material capable of inserting and extracting Li ions. For example, as a negative electrode active material, lithium such as graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), carbon fibers, etc. can be occluded / released. One type or a mixture of two or more types of carbonaceous materials are used. Further, elements such as Si, Sn, Ge, Bi, Sb, In and alloys thereof, compounds that can be charged and discharged at a low voltage close to lithium metal such as lithium-containing nitrides or lithium-containing oxides, or lithium metal or lithium / aluminum An alloy can also be used as the negative electrode active material. As the negative electrode, a negative electrode mixture in which a conductive additive (carbon material such as carbon black) or a binder (PVDF or the like) or the like is appropriately added to these negative electrode active materials, and a molded body (negative electrode) using the current collector as a core material A mixture layer) or a laminate of the above various alloys and lithium metal foils alone or on a current collector is used.
　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、下限は５μｍであることが望ましい。また、負極側のリード部は、正極側のリード部と同様にして形成すればよい。 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. Further, the lead portion on the negative electrode side may be formed in the same manner as the lead portion on the positive electrode side.
　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した積層型の電極群や、更にこれを巻回した巻回体電極群の形態で用いることができる。なお、本発明の電気化学素子では、折り曲げ時の耐短絡性に優れた本発明のセパレータを用いていることから、セパレータに変形を加える巻回体電極群を用いた場合に、その効果がより顕著となり、セパレータを強く屈曲させる扁平状の巻回体電極群（横断面が扁平状の巻回体電極群）を用いた場合に、その効果が特に顕著となる。 The electrode can be used in the form of a stacked electrode group in which the positive electrode and the negative electrode are stacked via the separator of the present invention, or a wound electrode group in which the electrode is wound. In addition, in the electrochemical element of the present invention, since the separator of the present invention excellent in short circuit resistance at the time of bending is used, the effect is more effective when a wound electrode group that deforms the separator is used. When the flat wound electrode group that strongly bends the separator (a wound electrode group having a flat cross section) is used, the effect is particularly remarkable.
　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しにく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を示す。〕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 hardly causes side reactions such as decomposition in a voltage range used as a battery. For example, LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 and other inorganic lithium salts, 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 [wherein R f represents a fluoroalkyl group. An organic lithium salt such as] can be used.
　非水電解質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－ブチロラクトンなどの環状エステル；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などのニトリル類；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、これらは２種以上混合して用いることもできる。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、これらの非水電解質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、シクロヘキサン、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 for the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause a side reaction such as decomposition in a voltage range used as a battery. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and 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 dimethoxyethane, 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, etc., and these may be used as a mixture of two or more. Kill. 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, cyclohexane, biphenyl, fluorobenzene, t for the purpose of improving the safety, charge / discharge cycleability, and high-temperature storage properties of these nonaqueous electrolytes. -Additives such as butylbenzene can be added as appropriate.
　このリチウム塩の非水電解質中の濃度としては、０．５～１．５ｍｏｌ／Ｌとすることが好ましく、０．９～１．３ｍｏｌ／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 1.3 mol / L.
　本発明の電気化学素子は、従来から知られている電気化学素子と同様の用途に用いることができる。 The electrochemical device of the present invention can be used for the same applications as conventionally known electrochemical devices.
　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）
　＜セパレータの作製＞
　オリゴマーであるウレタンアクリレート：３．５質量部、モノマー（架橋剤）であるジペントキシ化ペンタエリストールジアクリレート：３．５質量部、光重合開始剤である２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシド：０．０５質量部、無機微粒子Ｂであるベーマイト（平均粒径０．６μｍ）：３２．９５質量部、および揮発性物質であるトルエン：６０質量部を均一に混合してセパレータ形成用のスラリーを調製した。このスラリー中に厚みが１２μｍのＰＥＴ製不織布を通し、引き上げ塗布によりスラリーを塗布した後、所定の間隔を有するギャップの間を通し、続いて波長３６５ｎｍの紫外線を照度６０ｍＷ／ｃｍ２で１０秒間照射し、その後乾燥してトルエンを除去し、厚みが１６μｍのセパレータを得た。 Example 1
<Preparation of separator>
Urethane acrylate as an oligomer: 3.5 parts by mass, dipentoxylated pentaerythritol diacrylate as a monomer (crosslinking agent): 3.5 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine as a photopolymerization initiator Oxide: 0.05 parts by mass, inorganic fine particle B boehmite (average particle size 0.6 μm): 32.95 parts by mass, and volatile substance toluene: 60 parts by mass for uniform mixing. A slurry was prepared. A PET nonwoven fabric with a thickness of 12 μm is passed through the slurry, and the slurry is applied by pulling up and then passing through a gap having a predetermined interval, followed by irradiation with ultraviolet light having a wavelength of 365 nm for 10 seconds at an illuminance of 60 mW / cm 2. Then, it was dried to remove toluene, and a separator having a thickness of 16 μm was obtained.
　＜正極の作製＞
　正極活物質であるＬｉＣｏＯ２：９０質量部、導電助剤であるアセチレンブラック：７質量部、およびバインダであるＰＶＤＦ：３質量部を、Ｎ－メチル－２－ピロリドン（ＮＭＰ）を溶剤として均一になるように混合し、正極合剤含有ペーストを調製した。このペーストを集電体となる厚み１５μｍのアルミニウム箔の両面に、塗布長が表２８０ｍｍ、裏面２１０ｍｍになるように間欠塗布し、乾燥した後、カレンダー処理を行って、全厚が１５０μｍになるように正極合剤層の厚みを調整し、幅４３ｍｍになるように切断して正極を作製した。その後、正極におけるアルミニウム箔の露出部にタブ付けを行った。 <Preparation of positive electrode>
LiCoO 2 as a positive electrode active material: 90 parts by mass, acetylene black as a conductive auxiliary agent: 7 parts by mass, and PVDF as a binder: 3 parts by mass uniformly using N-methyl-2-pyrrolidone (NMP) as a solvent It mixed so that positive electrode mixture containing paste might be prepared. This paste is intermittently applied on both sides of an aluminum foil having a thickness of 15 μm as a current collector so that the coating length is 280 mm and the back surface is 210 mm, dried, and then calendered so that the total thickness becomes 150 μm. The thickness of the positive electrode mixture layer was adjusted, and the positive electrode was prepared by cutting to a width of 43 mm. Then, tab attachment was performed to the exposed part of the aluminum foil in a positive electrode.
　＜負極の作製＞
　負極活物質である黒鉛：９５質量部とＰＶＤＦ：５質量部とを、ＮＭＰを溶剤として均一になるように混合して負極合剤含有ペーストを調製した。このペーストを銅箔からなる厚み１０μｍの集電体の両面に、塗布長が表２９０ｍｍ、裏面２３０ｍｍになるように間欠塗布し、乾燥した後、カレンダー処理を行って、全厚が１４２μｍになるように負極合剤層の厚みを調整し、幅４５ｍｍになるように切断して負極を作製した。その後、負極における銅箔の露出部にタブ付けを行った。 <Production of negative electrode>
A negative electrode active material-containing paste was prepared by mixing 95 parts by mass of graphite serving as the negative electrode active material and 5 parts by mass of PVDF so as to be uniform using NMP as a solvent. This paste is intermittently applied to both sides of a 10 μm thick collector made of copper foil so that the coating length is 290 mm on the front and 230 mm on the back, dried, and then calendered to a total thickness of 142 μm. The negative electrode mixture layer was adjusted in thickness and cut to a width of 45 mm to prepare a negative electrode. Then, tab attachment was performed to the exposed part of the copper foil in a negative electrode.
　＜電池の組み立て＞
　前記のようにして得た正極と負極とを、前記のセパレータを介在させつつ重ね、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押しつぶして扁平状にし、厚み４ｍｍ、高さ５０ｍｍ、幅３４ｍｍのアルミニウム製外装缶に入れ、電解液（エチレンカーボネートとエチルメチルカーボネートを体積比で１対２に混合した溶媒にＬｉＰＦ６を濃度１．２ｍｏｌ／Ｌで溶解したもの）を注入した後に封止を行って、図１Ａ、Ｂに示す構造で、図２に示す外観の角形非水電解質二次電池を作製した。 <Battery assembly>
The positive electrode and the negative electrode obtained as described above were overlapped with the separator interposed therebetween and wound in a spiral shape to produce a wound body electrode group. The obtained wound body electrode group is crushed into a flat shape, put into an aluminum outer can having a thickness of 4 mm, a height of 50 mm, and a width of 34 mm, and an electrolytic solution (ethylene carbonate and ethyl methyl carbonate are mixed in a volume ratio of 1: 2). was the LiPF 6 that was dissolved at a concentration 1.2 mol / L in a solvent) performing sealing after injection of, FIG. 1A, the structure shown in B, and prismatic nonaqueous electrolyte secondary battery of the appearance shown in FIG. 2 Produced.
　ここで、図１Ａ、Ｂおよび図２に示す電池について説明すると、図１Ａは本実施例の非水電解質二次電池の平面図であり、図１Ｂは図１Ａの断面図である。図１Ｂに示すように、正極１と負極２は前記のようにセパレータ３を介して渦巻状に巻回した巻回体電極群６として、角形の外装缶４に非水電解液とともに収容されている。ただし、図１では、煩雑化を避けるため、正極１や負極２の作製にあたって使用した集電体としての金属箔や電解液などは図示していない。 Here, the battery shown in FIGS. 1A, 1B and 2 will be described. FIG. 1A is a plan view of the nonaqueous electrolyte secondary battery of this example, and FIG. 1B is a cross-sectional view of FIG. 1A. As shown in FIG. 1B, the positive electrode 1 and the negative electrode 2 are housed in a rectangular outer can 4 together with a non-aqueous electrolyte as a wound body electrode group 6 wound in a spiral shape through the separator 3 as described above. Yes. However, in FIG. 1, in order to avoid complication, a metal foil, an electrolytic solution, and the like as a current collector used for manufacturing the positive electrode 1 and the negative electrode 2 are not illustrated.
　外装缶４はアルミニウム合金製で電池の外装材を構成するものであり、この外装缶４は正極端子を兼ねている。そして、外装缶４の底部にはポリエチレンシートからなる絶縁体５が配置され、正極１、負極２およびセパレータ３からなる巻回体電極群６からは、正極１および負極２のそれぞれ一端に接続された正極リード体７と負極リード体８が引き出されている。また、外装缶４の開口部を封口するアルミニウム合金製の蓋板９にはポリプロピレン製の絶縁パッキング１０を介してステンレス鋼製の端子１１が取り付けられ、この端子１１には絶縁体１２を介してステンレス鋼製のリード板１３が取り付けられている。 The outer can 4 is made of an aluminum alloy and constitutes the outer casing of the battery. The outer can 4 also serves as a positive electrode terminal. And the insulator 5 which consists of a polyethylene sheet is arrange | positioned at the bottom part of the armored can 4, and from the wound body electrode group 6 which consists of the positive electrode 1, the negative electrode 2, and the separator 3, it connects to each one end of the positive electrode 1 and the negative electrode 2. The positive electrode lead body 7 and the negative electrode lead body 8 are drawn out. A stainless steel terminal 11 is attached to an aluminum alloy cover plate 9 that seals the opening of the outer can 4 via a polypropylene insulating packing 10, and an insulator 12 is connected to the terminal 11. A stainless steel lead plate 13 is attached.
　そして、この蓋板９は前記外装缶４の開口部に挿入され、両者の接合部を溶接することによって、外装缶４の開口部が封口され、電池内部が密閉されている。なお、蓋板９には電解液注入口１４が設けられており、電池組み立ての際には、この電解液注入口１４から電池内に電解液が注入され、その後、電解液注入口１４は封止される。また、蓋板９には、防爆用の安全弁１５が設けられている。 The cover plate 9 is inserted into the opening of the outer can 4 and welded to join the opening of the outer can 4 so that the inside of the battery is sealed. The lid plate 9 is provided with an electrolyte inlet 14, and when the battery is assembled, the electrolyte is injected into the battery from the electrolyte inlet 14, and then the electrolyte inlet 14 is sealed. Stopped. The cover plate 9 is provided with an explosion-proof safety valve 15.
　この実施例１の電池では、正極リード体７を蓋板９に直接溶接することによって外装缶４と蓋板９とが正極端子として機能し、負極リード体８をリード板１３に溶接し、そのリード板１３を介して負極リード体８と端子１１とを導通させることによって端子１１が負極端子として機能するようになっているが、外装缶４の材質などによっては、その正負が逆になる場合もある。 In the battery of Example 1, the outer can 4 and the lid plate 9 function as a positive electrode terminal by directly welding the positive electrode lead body 7 to the lid plate 9, and the negative electrode lead body 8 is welded to the lead plate 13. The terminal 11 functions as a negative electrode terminal by conducting the negative electrode lead body 8 and the terminal 11 through the lead plate 13, but depending on the material of the outer can 4, the sign may be reversed. There is also.
　図２は図１Ａ、Ｂに示す電池の外観を模式的に示す斜視図であり、この図２は前記電池が角形電池であることを示すことを目的として図示されたものであって、この図２では電池を概略的に示しており、電池の構成部材のうち特定のものしか図示していない。また、図１Ｂにおいても、巻回体電極群６の内周側の部分は断面にしておらず、セパレータ３では断面を示すハッチングを省略している。 FIG. 2 is a perspective view schematically showing the external appearance of the battery shown in FIGS. 1A and 1B. FIG. 2 is shown for the purpose of showing that the battery is a square battery. In FIG. 2, a battery is schematically shown, and only specific ones of the constituent members of the battery are illustrated. Also in FIG. 1B, the inner peripheral side portion of the wound body electrode group 6 is not cross-sectioned, and the cross-section hatching is omitted in the separator 3.
　（実施例２）
　オリゴマーであるウレタンアクリレート：１５質量部、モノマーであるジペントキシ化ペンタエリストールジアクリレート：１５質量部、光重合開始剤である２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシド：０．１５質量部、無機微粒子Ｂであるベーマイト（平均粒径０．６μｍ）：１０質量部、および揮発性物質であるトルエン：５９．８５質量部を均一に混合して調製したセパレータ形成用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。そして、このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Example 2)
Urethane acrylate as an oligomer: 15 parts by mass, dipentoxylated pentaerythritol diacrylate as a monomer: 15 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine oxide as a photopolymerization initiator: 0.15 parts by mass, Except for using a separator-forming slurry prepared by uniformly mixing 10 parts by weight of boehmite as an inorganic fine particle B (average particle size 0.6 μm) and 59.85 parts by weight of toluene as a volatile substance. A separator was produced in the same manner as in Example 1. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
　（実施例３）
　無機微粒子Ｂをチタニア（平均粒径０．６μｍ）に変更した以外は、実施例１と同様にしてセパレータ形成用のスラリーを調製し、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。そして、このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Example 3)
A slurry for forming a separator was prepared in the same manner as in Example 1 except that the inorganic fine particles B were changed to titania (average particle size 0.6 μm), and the same procedure as in Example 1 was performed except that this slurry was used. A separator was produced. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
　（実施例４）
　無機微粒子Ｂをアルミナ（平均粒径０．４μｍ）に変更した以外は、実施例１と同様にしてセパレータ形成用のスラリーを調製し、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。そして、このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 Example 4
A separator-forming slurry was prepared in the same manner as in Example 1 except that the inorganic fine particles B were changed to alumina (average particle size 0.4 μm), and the slurry was used in the same manner as in Example 1 except that this slurry was used. A separator was produced. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
　（実施例５）
　実施例１で調製したものと同じセパレータ形成用のスラリーを、ポリテトラフルオロエチレン製の基材表面に、ダイコーターを用いてギャップを４０μｍとして塗布し、続いて紫外線を照度６０ｍＷ／ｃｍ２で１０秒間照射し、乾燥した後に基材から引き剥がして、厚みが１６μｍのセパレータを得た。このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Example 5)
The same slurry for forming a separator as that prepared in Example 1 was applied to the surface of a polytetrafluoroethylene substrate with a gap of 40 μm using a die coater, followed by UV irradiation at an illuminance of 60 mW / cm 2 at 10. Irradiated for 2 seconds, dried, and then peeled off from the substrate to obtain a separator having a thickness of 16 μm. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　（実施例６）
　オリゴマーであるウレタンアクリレート：１３質量部、モノマーであるジペントキシ化ペンタエリストールジアクリレート：１３質量部、光重合開始剤である２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシド：０．１３質量部、無機微粒子Ｂであるベーマイト（平均粒径０．６μｍ）：１２．８７質量部、および揮発性物質であるトルエン：６１質量部を均一に混合してセパレータ形成用のスラリーを調製した。このスラリー中に厚みが１２μｍのＰＥＴ製不織布を通し、引き上げ塗布によりスラリーを塗布した後、所定の間隔を有するギャップの間を通し、続いて紫外線を照度６０ｍＷ／ｃｍ２で１０秒間照射し、その後乾燥して、厚みが１２μｍの多孔質膜を得た。その後、前記の多孔質膜の片面に、ＰＥ微粒子を含むエマルジョン（ＰＥ微粒子の平均粒径１．０μｍ）をダイコーターによって、乾燥後の厚みが４μｍとなるように塗布し、乾燥してシャットダウン層を形成して、セパレータを得た。このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Example 6)
Urethane acrylate as an oligomer: 13 parts by mass, dipentoxylated pentaerythritol diacrylate as a monomer: 13 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine oxide as a photopolymerization initiator: 0.13 parts by mass, A slurry for forming a separator was prepared by uniformly mixing boehmite as an inorganic fine particle B (average particle size 0.6 μm): 12.87 parts by mass and 61 parts by mass of toluene as a volatile substance. A PET nonwoven fabric having a thickness of 12 μm is passed through this slurry, and after applying the slurry by pulling up, it is passed through a gap having a predetermined interval, followed by irradiation with ultraviolet rays at an illuminance of 60 mW / cm 2 for 10 seconds, and then It dried and obtained the porous membrane whose thickness is 12 micrometers. Thereafter, an emulsion containing PE fine particles (average particle diameter of PE fine particles of 1.0 μm) is applied to one side of the porous film with a die coater so that the thickness after drying becomes 4 μm, and dried to form a shutdown layer. To obtain a separator. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this separator was used.
　（実施例７）
　オリゴマーであるウレタンアクリレート：１５．７質量部、モノマー（架橋剤）であるイソボルニルアクリレート：１０．４質量部、光重合開始剤である２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシド：０．７８質量部、無機微粒子Ｂであるベーマイト（平均粒径０．６μｍ）：２３．５質量部、および揮発性物質であるトルエン：４９．６２質量部を均一に混合して調製したセパレータ形成用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。そして、このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Example 7)
Urethane acrylate as an oligomer: 15.7 parts by mass, isobornyl acrylate as a monomer (crosslinking agent): 10.4 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine oxide as a photopolymerization initiator: 0 .78 parts by mass, Boehmite as an inorganic fine particle B (average particle size 0.6 μm): 23.5 parts by mass, and toluene as a volatile substance: 49.62 parts by mass for uniform mixing A separator was prepared in the same manner as in Example 1 except that this slurry was used. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
　（実施例８）
　実施例１で調製したものと同じセパレータ形成用のスラリーを、同じく実施例１で作製した負極上に、ダイコーターを用いてギャップを４０μｍとして塗布した。塗布後に紫外線を照度６０ｍＷ／ｃｍ２で１０秒間照射し、更に乾燥させて、負極合剤層上にセパレータが形成された電極（負極）を得た。前記セパレータは、負極の両面に形成し、負極合剤層とセパレータとが一体化された層の厚みは、負極の集電体の両面で、それぞれ７０μｍとした。 (Example 8)
The same slurry for forming the separator as that prepared in Example 1 was applied on the negative electrode similarly prepared in Example 1 with a gap of 40 μm using a die coater. After the application, ultraviolet rays were irradiated at an illuminance of 60 mW / cm 2 for 10 seconds and further dried to obtain an electrode (negative electrode) having a separator formed on the negative electrode mixture layer. The separator was formed on both sides of the negative electrode, and the thickness of the layer in which the negative electrode mixture layer and the separator were integrated was 70 μm on both sides of the negative electrode current collector.
　前記セパレータと一体化された電極（負極）と、実施例１で作製した正極とを、それらの間に別のセパレータを介在させずに重ね、渦巻状に巻回して巻回体電極群を作製した。以下、実施例１と同様にして非水電解質二次電池を作製した。 The electrode (negative electrode) integrated with the separator and the positive electrode prepared in Example 1 are stacked without interposing another separator therebetween, and wound to form a wound electrode group. did. Thereafter, a nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.
　（実施例９）
　実施例１で調製したものと同じセパレータ形成用のスラリーを、同じく実施例１で作製した負極上に、ダイコーターを用いてギャップを３μｍとして塗布した。塗布後に紫外線を照度６０ｍＷ／ｃｍ２で１０秒間照射し、更に乾燥させて、負極合剤層上にセパレータが形成された電極（負極）を得た。前記セパレータは、負極の両面に形成し、負極合剤層とセパレータとが一体化された層の厚みは、負極の集電体の両面で、それぞれ５μｍｍとした。 Example 9
The same slurry for forming a separator as that prepared in Example 1 was applied on the negative electrode similarly prepared in Example 1 with a gap of 3 μm using a die coater. After the application, ultraviolet rays were irradiated at an illuminance of 60 mW / cm 2 for 10 seconds and further dried to obtain an electrode (negative electrode) having a separator formed on the negative electrode mixture layer. The separator was formed on both sides of the negative electrode, and the thickness of the layer in which the negative electrode mixture layer and the separator were integrated was 5 μm on each side of the negative electrode current collector.
　前記セパレータと一体化された電極（負極）と、実施例１で作製した正極とを、それらの間に別のセパレータを介在させずに重ね、渦巻状に巻回して巻回体電極群を作製した。以下、実施例１と同様にして非水電解質二次電池を作製した。 The electrode (negative electrode) integrated with the separator and the positive electrode prepared in Example 1 are stacked without interposing another separator therebetween, and wound to form a wound electrode group. did. Thereafter, a nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.
　（比較例１）
　オリゴマーであるウレタンアクリレート：２質量部、モノマーであるジペントキシ化ペンタエリストールジアクリレート：２質量部、光重合開始剤である２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシド：０．０２質量部、無機微粒子Ｂであるベーマイト（平均粒径０．６μｍ）：３５．９８質量部、および揮発性物質であるトルエン：６０質量部を均一に混合して調製したセパレータ形成用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。そして、このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Comparative Example 1)
Urethane acrylate as an oligomer: 2 parts by mass, dipentoxylated pentaerythritol diacrylate as a monomer: 2 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine oxide as a photopolymerization initiator: 0.02 parts by mass, Except for using a slurry for forming a separator prepared by uniformly mixing boehmite as an inorganic fine particle B (average particle size 0.6 μm): 35.98 parts by mass and toluene as a volatile material: 60 parts by mass. A separator was produced in the same manner as in Example 1. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
　（比較例２）
　オリゴマーであるウレタンアクリレート：１６質量部、モノマーであるジペントキシ化ペンタエリストールジアクリレート：１６質量部、光重合開始剤である２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシド：０．１６質量部、無機微粒子Ｂであるベーマイト（平均粒径０．６μｍ）：７．８４質量部、および揮発性物質であるトルエン：６０質量部を均一に混合して調製したセパレータ形成用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。そして、このセパレータを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Comparative Example 2)
Urethane acrylate as an oligomer: 16 parts by mass, dipentoxylated pentaerythritol diacrylate as a monomer: 16 parts by mass, 2,4,6-trimethylbenzoylbisphenylphosphine oxide as a photopolymerization initiator: 0.16 parts by mass, Except for using a separator forming slurry prepared by uniformly mixing boehmite (average particle size 0.6 μm) as inorganic fine particles B: 7.84 parts by mass and toluene as a volatile material: 60 parts by mass. A separator was produced in the same manner as in Example 1. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this separator.
　（比較例３）
　厚みが１６μｍのＰＥ製微多孔膜をセパレータに用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。 (Comparative Example 3)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that a PE microporous membrane having a thickness of 16 μm was used as the separator.
　（比較例４）
　実施例１の、ウレタンアクリレートとジペントキシ化ペンタエリストールジアクリレートと２，４，６－トリメチルベンゾイルビスフェニルホスフィンオキシドの代わりに、ポリアクリル酸：７．０５質量部、無機微粒子Ｂであるベーマイト（平均粒径０．６μｍ）：３２．９５質量部、および揮発性物質であるイソプロパノール：６０質量部を均一に混合してセパレータ形成用のスラリーを調製した。 (Comparative Example 4)
In place of urethane acrylate, dipentoxylated pentaerythritol diacrylate and 2,4,6-trimethylbenzoylbisphenylphosphine oxide in Example 1, polyacrylic acid: 7.05 parts by mass, boehmite as inorganic fine particles B (average Particle size 0.6 μm): 32.95 parts by mass, and isopropanol as a volatile substance: 60 parts by mass were uniformly mixed to prepare a slurry for forming a separator.
　このスラリーを実施例１で作製した負極上に、ダイコーターを用いてギャップを９μｍとして塗布した。塗布後に紫外線を照度６０ｍＷ／ｃｍ２で１０秒間照射し、更に乾燥させて、負極合剤層上にセパレータが形成された電極（負極）を得た。前記セパレータは、負極の両面に形成し、負極合剤層とセパレータとが一体化された層の厚みは、負極の集電体の両面で、それぞれ１６μｍとした。 This slurry was applied on the negative electrode prepared in Example 1 with a gap of 9 μm using a die coater. After the application, ultraviolet rays were irradiated at an illuminance of 60 mW / cm 2 for 10 seconds and further dried to obtain an electrode (negative electrode) having a separator formed on the negative electrode mixture layer. The separator was formed on both sides of the negative electrode, and the thickness of the layer in which the negative electrode mixture layer and the separator were integrated was 16 μm on each side of the negative electrode current collector.
　前記セパレータと一体化された電極（負極）と、実施例１で作製した正極とを、それらの間に別のセパレータを介在させずに重ね、渦巻状に巻回して巻回体電極群を作製した。以下、実施例１と同様にして非水電解質二次電池を作製した。 The electrode (negative electrode) integrated with the separator and the positive electrode prepared in Example 1 are stacked without interposing another separator therebetween, and wound to form a wound electrode group. did. Thereafter, a nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.
　実施例１～９および比較例１～４の非水電解質二次電池に使用したセパレータの構成を表１に示す。 Table 1 shows the configurations of the separators used in the nonaqueous electrolyte secondary batteries of Examples 1 to 9 and Comparative Examples 1 to 4.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１において、「ａ／ｂ値」とは、樹脂Ａの体積ａ（空孔体積を除いた体積）と無機微粒子Ｂの体積ｂ（空孔体積を除いた体積）との比ａ／ｂを意味し、「樹脂Ａと無機微粒子Ｂとの総量」とは、セパレータの構成成分の全体積（空孔体積を除いた体積）に対する樹脂Ａの体積ａ（空孔体積を除いた体積）と無機微粒子Ｂの体積ｂ（空孔体積を除いた体積）との合計体積の割合を意味する。 In Table 1, “a / b value” means the ratio a / b between the volume a of the resin A (volume excluding the void volume) and the volume b of the inorganic fine particle B (volume excluding the void volume). It means that “the total amount of resin A and inorganic fine particles B” means the volume a of resin A (volume excluding pore volume) and inorganic relative to the total volume (volume excluding pore volume) of the constituent components of the separator. It means the ratio of the total volume with the volume b (volume excluding pore volume) of the fine particles B.
　先ず、実施例１～９の非水電解質二次電池に用いたセパレータについて、高温での寸法安定性を確認した。すなわち、各セパレータ（実施例８および９では負極一体化セパレータ）を１５０℃の恒温槽中で１時間保持し、保持前の寸法（幅および長さ）と保持後の寸法を比較した。その結果、寸法変化は認められず、高温下での収縮による電池の安全性低下を防ぐことのできるセパレータであることが確認できた。 First, the dimensional stability at high temperatures was confirmed for the separators used in the nonaqueous electrolyte secondary batteries of Examples 1 to 9. That is, each separator (in Example 8 and 9, negative electrode integrated separator) was held in a thermostat at 150 ° C. for 1 hour, and the dimensions (width and length) before holding were compared with the dimensions after holding. As a result, no dimensional change was observed, and it was confirmed that the separator was able to prevent a decrease in battery safety due to shrinkage at high temperatures.
　次に、実施例１～９および比較例１～４の非水電解質二次電池について、以下の充放電試験を行った。すなわち、各電池について、０．２Ｃの電流で４．２Ｖまで定電流充電し、その後４．２Ｖでの定電圧充電を行った。総充電時間は、８時間とした。定電圧充電の終了時点で電流が０．０２Ｃ以下にならなかった電池は、微短絡が発生したものと判断した。そして、微短絡が発生していない電池について、内部抵抗を測定してから、０．２Ｃの電流で３Ｖまで定電流放電した。更に、放電後の各電池について、前記と同じ条件で充電を行い、その後に２Ｃの電流で３Ｖまで定電流放電して、良好な充放電特性が得られているかを確認した。以上の結果を表２に示す。 Next, the following charge / discharge tests were performed on the nonaqueous electrolyte secondary batteries of Examples 1 to 9 and Comparative Examples 1 to 4. That is, for each battery, constant current charging to 4.2 V was performed at a current of 0.2 C, and then constant voltage charging was performed at 4.2 V. The total charging time was 8 hours. A battery whose current did not become 0.02 C or less at the end of constant voltage charging was judged to have caused a slight short circuit. And about the battery in which the fine short circuit did not generate | occur | produce, after measuring internal resistance, it discharged at constant current to 3V with the electric current of 0.2C. Further, each of the batteries after discharging was charged under the same conditions as described above, and thereafter, constant current discharging was performed up to 3 V with a current of 2 C, and it was confirmed whether good charge / discharge characteristics were obtained. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　更に、シャットダウン樹脂を有するセパレータを用いた実施例６および比較例３の電池については、シャットダウン特性評価のために、充放電試験時と同じ条件で充電を行った後に恒温槽に入れ、３０℃から１５０℃まで毎分１℃の割合で温度上昇させて加熱し、電池の内部抵抗の温度変化を求めた。そして、抵抗値が３０℃での値の５倍以上に上昇した時の温度を、そのセパレータのシャットダウン温度とした。また、電池の温度が１５０℃に到達した後で、その状態で恒温槽の温度を１５０℃で２時間保持する昇温試験を行った。昇温試験中に、電池の様子を観察し、電池の最高到達温度を測定した。また、昇温試験後の電池の電圧を測定した。以上の結果を表３に示す。 Furthermore, for the batteries of Example 6 and Comparative Example 3 using the separator having the shutdown resin, for the shutdown characteristics evaluation, after charging under the same conditions as those during the charge / discharge test, the batteries were put into a thermostatic bath and from 30 ° C. The temperature was raised to 150 ° C. at a rate of 1 ° C. per minute, and the temperature was changed by measuring the internal resistance of the battery. The temperature at which the resistance value increased to 5 times or more the value at 30 ° C. was taken as the shutdown temperature of the separator. Further, after the temperature of the battery reached 150 ° C., a temperature increase test was performed in which the temperature of the thermostatic bath was maintained at 150 ° C. for 2 hours. During the temperature increase test, the state of the battery was observed and the maximum temperature reached by the battery was measured. Further, the voltage of the battery after the temperature increase test was measured. The above results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表２から明らかなように、光重合により形成され、少なくとも一部に架橋構造を有する樹脂Ａと、無機微粒子Ｂとを適正な組成比で含有するセパレータを使用した実施例１～９の非水電解質二次電池は、微短絡の発生がなく、充放電特性が良好であった。また、前述のように、実施例１～９の電池で使用したセパレータは高温下での寸法安定性に優れていることから、表３に示す通り、実施例６の非水電解質二次電池は昇温試験後における電圧低下が小さく、シャットダウン機能を有効に作用させることができるために、昇温試験時の温度上昇が抑えられており、高い信頼性と安全性とを有していた。 As is apparent from Table 2, the non-aqueous solutions of Examples 1 to 9 using a separator formed by photopolymerization and containing at least a resin A having a crosslinked structure and inorganic fine particles B in an appropriate composition ratio. The electrolyte secondary battery did not cause a fine short circuit and had good charge / discharge characteristics. As described above, since the separators used in the batteries of Examples 1 to 9 are excellent in dimensional stability at high temperatures, as shown in Table 3, the nonaqueous electrolyte secondary battery of Example 6 is Since the voltage drop after the temperature increase test is small and the shutdown function can be effectively operated, the temperature increase during the temperature increase test is suppressed, and high reliability and safety are obtained.
　これに対し、樹脂Ａの体積と無機微粒子Ｂとの体積との比であるａ／ｂ値が小さすぎるセパレータを用いた比較例１の電池、およびａ／ｂ値が大きすぎるセパレータを用いた比較例２の電池では、充放電試験における充電時に微短絡が生じていた。これらは、比較例１の電池ではセパレータの柔軟性が欠如していることにより、また、比較例２の電池ではセパレータにおける無機微粒子Ｂの少なさにより、それぞれ正負極間の耐短絡性が欠如したためと推測される。更に、通常のＰＥ製微多孔膜セパレータを用いた比較例３の電池では、昇温試験において、最高到達温度が高くなり、試験後の電圧も０Ｖ近辺まで低下しているが、これは、セパレータの熱収縮および破膜が生じた結果、正負極間で短絡が発生したためと考えられる。 On the other hand, the battery of the comparative example 1 using the separator whose a / b value which is the ratio of the volume of the resin A and the volume of the inorganic fine particles B is too small, and the comparison using the separator whose a / b value is too large In the battery of Example 2, a slight short circuit occurred during charging in the charge / discharge test. These are because the battery of Comparative Example 1 lacks the flexibility of the separator, and the battery of Comparative Example 2 lacks short-circuit resistance between the positive and negative electrodes due to the small amount of inorganic fine particles B in the separator. It is guessed. Furthermore, in the battery of Comparative Example 3 using a normal PE microporous membrane separator, the highest temperature reached in the temperature increase test, and the voltage after the test decreased to around 0 V. This is probably because a short circuit occurred between the positive and negative electrodes as a result of heat shrinkage and film breakage.
　また、実施例８、９および比較例４のセパレータについて、柔軟性評価を行った。柔軟性評価は、それぞれ得られたセパレータ一体化電極と、実施例１で作製した正極とを巻回体にした後、９０℃の熱プレス機により圧力２ｔで１時間巻回体を押しつぶし、プレスした後の巻回体のひび割れの有無を目視で観察した。その結果、実施例８および９のセパレータを用いた巻回体では、ひび割れは観察されなかったが、比較例４のセパレータを用いた巻回体では、ひび割れが観察された。また、プレス後の各巻回体を用いて実施例１と同様にして非水電解質二次電池を作製し、前述と同様にして充放電試験を行ったところ、実施例８および９のセパレータを用いた電池では、短絡は認められなかったが、比較例４のセパレータを用いた電池では、前述と同様の判断基準に基づき、微短絡が発生していると判断する結果となった。 Further, the flexibility of the separators of Examples 8 and 9 and Comparative Example 4 was evaluated. Flexibility evaluation was carried out by making each separator integrated electrode obtained and the positive electrode produced in Example 1 into a wound body, and then crushing the wound body for 1 hour at a pressure of 2 t with a 90 ° C. heat press. The presence or absence of cracks in the wound body after the observation was visually observed. As a result, cracks were not observed in the wound bodies using the separators of Examples 8 and 9, but cracks were observed in the wound body using the separators of Comparative Example 4. In addition, a non-aqueous electrolyte secondary battery was prepared using each wound body after pressing in the same manner as in Example 1, and a charge / discharge test was performed in the same manner as described above. The separators in Examples 8 and 9 were used. However, in the battery using the separator of Comparative Example 4, it was determined that a slight short circuit occurred based on the same criteria as described above.
　なお、実施例１～７の電池に用いたセパレータ、および、実施例８および９の電池に用いたセパレータ一体化電極は、簡単な工程のみで製造可能であるため、セパレータ並びに電池（電気化学素子）の生産性を高めることができる。 Since the separator used in the batteries of Examples 1 to 7 and the separator integrated electrode used in the batteries of Examples 8 and 9 can be manufactured by only a simple process, the separator and the battery (electrochemical element) ) Productivity.
　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　外装缶
　５　絶縁体
　６　巻回体電極群
　７　正極リード体
　８　負極リード体
　９　蓋板
１０　絶縁パッキング
１１　端子
１２　絶縁体
１３　リード板
１４　電解液注入口
１５　安全弁
  DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Exterior can 5 Insulator 6 Winding body electrode group 7 Positive electrode lead body 8 Negative electrode lead body 9 Cover plate 10 Insulation packing 11 Terminal 12 Insulator 13 Lead plate 14 Electrolyte injection port 15 Safety valve

Claims (9)

  1. 　光重合により形成され、架橋構造を有する樹脂Ａと、電気絶縁性の無機微粒子Ｂとを含む電気化学素子用セパレータであって、
    　空孔体積を除き、前記樹脂Ａの体積ａと、前記無機微粒子Ｂの体積ｂとの比ａ／ｂが、０．６～９であることを特徴とする電気化学素子用セパレータ。     A separator for an electrochemical device, which is formed by photopolymerization and includes a resin A having a crosslinked structure and electrically insulating inorganic fine particles B,
    A separator for an electrochemical element, wherein a ratio a / b between the volume a of the resin A and the volume b of the inorganic fine particles B is 0.6 to 9, excluding the pore volume.
  2. 　前記無機微粒子Ｂが、アルミナ、チタニア、シリカおよびベーマイトからなる群から選択される少なくとも一つである請求項１に記載の電気化学素子用セパレータ。 The separator for an electrochemical element according to claim 1, wherein the inorganic fine particles B are at least one selected from the group consisting of alumina, titania, silica and boehmite.
  3. 　繊維状物を更に含む請求項１に記載の電気化学素子用セパレータ。 The separator for an electrochemical element according to claim 1, further comprising a fibrous material.
  4. 　融点が８０～１４０℃の熱溶融性樹脂Ｃ、および、加熱により液状の非水電解質を吸収して膨潤し且つ温度上昇と共に膨潤度が増大する熱膨潤性樹脂Ｄから選ばれる少なくとも一方を更に含む請求項１に記載の電気化学素子用セパレータ。 It further includes at least one selected from a heat-meltable resin C having a melting point of 80 to 140 ° C. and a heat-swellable resin D that absorbs a liquid nonaqueous electrolyte by heating and swells and the degree of swelling increases as the temperature rises. The separator for an electrochemical element according to claim 1.
  5. 　請求項１に記載の電気化学素子用セパレータと一体化されたことを特徴とする電気化学素子用電極。 An electrode for an electrochemical element integrated with the separator for an electrochemical element according to claim 1.
  6. 　正極、負極、セパレータおよび非水電解質を含む電気化学素子であって、
    　前記セパレータが、請求項１に記載の電気化学素子用セパレータであることを特徴とする電気化学素子。     An electrochemical device comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte,
    The said separator is an electrochemical element separator of Claim 1, The electrochemical element characterized by the above-mentioned.
  7. 　前記セパレータが、正極または負極と一体化された請求項６に記載の電気化学素子。 The electrochemical element according to claim 6, wherein the separator is integrated with a positive electrode or a negative electrode.
  8. 　請求項１に記載の電気化学素子用セパレータの製造方法であって、
    　揮発性物質を含む電気化学素子用セパレータ形成用のシートから、前記揮発性物質を揮発させて空孔を形成する工程、または、特定の溶剤に溶解し得る材料を含む電気化学素子用セパレータ形成用のシートから、前記溶剤により前記材料を抽出することで空孔を形成する工程を含むことを特徴とする電気化学素子用セパレータの製造方法。     It is a manufacturing method of the separator for electrochemical elements according to claim 1,
    A process for forming a hole by volatilizing the volatile substance from a sheet for forming an electrochemical element separator containing a volatile substance, or for forming a separator for an electrochemical element containing a material that can be dissolved in a specific solvent The manufacturing method of the separator for electrochemical elements characterized by including the process of forming a void | hole by extracting the said material with the said solvent from the sheet | seat of this.
  9. 　前記揮発性物質が、水または有機溶剤である請求項８に記載の電気化学素子用セパレータの製造方法。
          The method for producing a separator for an electrochemical element according to claim 8, wherein the volatile substance is water or an organic solvent.
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