WO2015008673A1 - Battery separator - Google Patents

Battery separator Download PDF

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Publication number
WO2015008673A1
WO2015008673A1 PCT/JP2014/068281 JP2014068281W WO2015008673A1 WO 2015008673 A1 WO2015008673 A1 WO 2015008673A1 JP 2014068281 W JP2014068281 W JP 2014068281W WO 2015008673 A1 WO2015008673 A1 WO 2015008673A1
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WO
WIPO (PCT)
Prior art keywords
separator
mass
battery
composite
aluminum oxide
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PCT/JP2014/068281
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French (fr)
Japanese (ja)
Inventor
高岡　和千代
中島　敏充
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三菱製紙株式会社
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Application filed by 三菱製紙株式会社 filed Critical 三菱製紙株式会社
Priority to CN201480039799.3A priority Critical patent/CN105359299B/en
Publication of WO2015008673A1 publication Critical patent/WO2015008673A1/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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a battery separator.
  • a battery separator (hereinafter sometimes abbreviated as a “separator”) used in a lithium secondary battery, a polyolefin porous film having through holes has been used.
  • This separator suppresses heat generation by increasing the internal resistance of the battery when the battery generates heat due to abnormalities and melts and closes through the fine holes, and thermal runaway of lithium cobaltate, which is the electrode agent It has been responsible for suppressing the explosion of batteries.
  • a separator in which a porous support having a hole such as a nonwoven fabric and a porous film made of a ceramic material are combined.
  • heat resistance is imparted by the porous ceramic material, and even when a thermal runaway of the battery occurs, thermal contraction of the separator hardly occurs and contact between the electrodes is suppressed (for example, see Patent Document 1).
  • the ceramic material is present on the surface of the separator and also penetrates into the separator, so that it is possible to impart high electrolyte retention and heat resistance.
  • Porous membranes and inorganic layers made of ceramic materials include aluminum oxide, zirconium oxide, silicon oxide, titanium oxide, barium titanate, lead titanate, strontium titanate and other inorganic fine particles such as titanium oxide and composite oxides thereof. It is common to contain. Among these, aluminum oxide is one of the most frequently used inorganic fine particles.
  • aluminum hydroxide oxide (AlOOH) obtained by hydrothermal synthesis can be obtained in various forms such as plate-like, granular, and needle-like, depending on the conditions during hydrothermal synthesis. It is a particularly preferable material because it can form a specific and large internal space and has excellent wettability with respect to an electrolyte for a lithium secondary battery.
  • AlOOH aluminum hydroxide oxide
  • Due to structural water derived from the raw material aluminum hydroxide there is a problem in durability with respect to the electrolytic solution, and there may be a problem in durability when repeated charging and discharging are performed (for example, Patent Documents 4 to 4). 6).
  • the thickness of the conventional separator was about 30 ⁇ m, in recent years, there has been a strong demand for thinning the separator, and a thinned separator having a thickness of 25 ⁇ m or less is required. Lesser separators are also desired. For this reason, restrictions have been placed on the particle shape and size of the aluminum oxide used in the separator. If the particle size is reduced and the aluminum oxide filling structure becomes too dense, the internal resistance of the separator may increase. With conventional aluminum oxides, it has not been easy to satisfy all of the problems of durability against electrolyte, low internal resistance, and thinning of the separator.
  • Japanese Patent No. 4594098 Special table 2008-503049 gazette Japanese Patent No. 4499851 Japanese Patent No. 4426721 International Publication No. 2008/114727 Pamphlet JP 2013-254677 A
  • An object of the present invention is to provide a battery separator that uses aluminum oxide, has excellent durability against electrolytes, can meet the demand for thinning the separator, and can reduce the internal resistance of the battery. Is to provide.
  • the battery separator as described.
  • the present invention provides a battery separator using an aluminum oxide, which has excellent durability against an electrolyte, can meet the demand for thinning the separator, and can reduce the internal resistance of the battery. be able to.
  • 2 is an X-ray diffraction spectrum of an aluminum oxide composite 8.
  • 2 is an X-ray diffraction spectrum of an aluminum oxide composite 9.
  • the durability to the electrolytic solution is inferior, and water is easily released at about 150 ° C., so the hydrolysis of the electrolytic solution in the battery is promoted and the battery characteristics deteriorate. It becomes a factor of.
  • the structure of aluminum oxide is main, the wettability of the electrolytic solution is lowered and the internal resistance of the battery is increased.
  • the oxygen / aluminum element ratio of the aluminum oxide composite is measured by energy dispersive X-ray spectroscopy (EDS).
  • EDS energy dispersive X-ray spectroscopy
  • This measurement method utilizes the principle that an element excited by an electron beam emits a specific X-ray, and is an excellent method capable of simultaneously measuring the oxygen / aluminum element ratio with a measurement accuracy of 5% or less. In general, it can be measured by adding a special spectroscopic device to a scanning electron microscope (SEM), and the penetration distance of electron beam to the material is about several ⁇ m, so an almost average element ratio of the observed specimen can be obtained.
  • SEM scanning electron microscope
  • starting materials for hydrothermal synthesis include aluminum hydroxide, ammonium aluminum carbonate (Ammonium Carbonate Hydroxide, AACH) and the like.
  • AlO (OH) 3 aluminum hydroxide oxide
  • Boehmite aluminum hydroxide oxide
  • an excessive hydroxyl group promotes hydrolysis of the electrolytic solution, which is not preferable.
  • the heating temperature is preferably 350 to 500 ° C, more preferably 400 to 470 ° C. However, when the heating temperature is less than 400 ° C., the reaction rate is slow and unsuitable for large-scale synthesis, and when the heating temperature exceeds 450 ° C., it may be gradually rearranged to aluminum oxide.
  • the temperature is 400-450 ° C.
  • AACH amorphous aluminum oxide
  • aluminum hydroxide examples include aluminum hydroxide such as gibbsite and bayerite. Further, high-purity aluminum hydroxide via an organoaluminum compound such as aluminum alkoxide can also be used.
  • alkali metal ions or ammonia may be used in combination.
  • ammonia is added or a small amount of sodium or potassium ion is added, a cube or plate is obtained.
  • magnesium ion is added, needles and the like are obtained.
  • irregularly shaped particles can also be obtained by using together an organic compound having a hydroxyl group or a carboxylic acid.
  • Aluminum hydroxide or AACH as a raw material may be used after adjusting the particle size in advance by a wet disperser such as a ball mill.
  • P1 ⁇ P2 X-ray diffraction
  • the X-ray diffraction intensity was measured using an X-ray diffraction intensity measuring apparatus “X'PertPRO” manufactured by PANalytical, using an aluminum oxide composite as a powder, and a CuK ⁇ ray as a radiation source.
  • the average particle size of the inorganic fine particles in the present invention is preferably 0.1 to 3.0 ⁇ m, more preferably 0.1 to 1.5 ⁇ m, and still more preferably 0.2 to 1.0 ⁇ m.
  • the average particle size is obtained by sufficiently diluting the inorganic fine particles with water and measuring this with a laser scattering type particle size measuring device (trade name: 3300EX2 manufactured by Microtrac) (D50). , Volume average).
  • the average pore diameter formed by the porous membrane layer is an important factor.
  • the internal short circuit internal short circuit
  • the ratio of the discharge capacity to the charge capacity is reduced, or the charge / discharge characteristics are disrupted, such as the inability to charge.
  • the coating amount and thickness are required.
  • the average particle diameter of the inorganic fine particles is 0.2 to 1.0 ⁇ m. It has been found that it is preferred. Within this range, stable charge / discharge characteristics can be obtained.
  • the average particle size of the inorganic fine particles is particularly preferably 0.4 to 0.8 ⁇ m.
  • the average pore size is measured by Porous Materials Inc. Measurement was performed with a manufactured Capillary Flow Porometer CEP-1500A.
  • the aluminum oxide composite obtained when AACH is used as a starting material for hydrothermal synthesis has a basic structure with an average particle diameter of about 0.2 ⁇ m and has a granular structure close to a cube.
  • the aluminum oxide-based composite using AACH as a starting material is also characterized in that the average particle diameter can be easily controlled by wet bead mill dispersion or the like. It is preferable to the oxide-based composite.
  • the battery separator of the present invention is manufactured by coating or impregnating a porous support with a coating liquid that is an aqueous dispersion or a solvent dispersion of inorganic fine particles, and forming a porous membrane layer.
  • a coating liquid that is an aqueous dispersion or a solvent dispersion of inorganic fine particles, and forming a porous membrane layer.
  • a polymer binder or the like may be used in combination with the porous membrane layer.
  • a water-soluble cellulose derivative is a cellulose derivative synthesized by modifying a part of hydroxyl groups of ⁇ -glucose molecules bonded linearly by glycosidic bonds so as to be water-soluble.
  • the compound modified denatured by the (carboxy group) group, the methoxy group (methyoxy) group, the hydroxy ethoxy (hydroxyethoxy) group, and the hydroxypropoxy (hydroxypropoxy) group is shown.
  • a derivative substituted with a carboxymethoxy group is called carboxymethylcellulose (CMC), and can be water-solubilized as a sodium salt or an ammonium salt.
  • Methylcellulose containing only methoxy groups dissolves only in low-temperature water, and has a thermal gel property that gels an aqueous solution when the temperature rises. Moreover, it is excellent in foaming property and foaming property, and can behave like a nonionic polymer surfactant. In general, solubility and thermal gel properties can be controlled by combining a hydroxyethoxy group or a hydroxypropoxy group with a methoxy group. In addition, water-soluble cationized cellulose can also be used. However, since cellulose derivatives such as cellulose acetate and ethyl cellulose are water-insoluble cellulose derivatives that do not dissolve in water, it is difficult to use them in aqueous dispersions.
  • the water-soluble cellulose derivative can be used in combination with inorganic fine particles to form a porous film layer and reduce internal resistance. If the content of the water-soluble cellulose derivative is too large, a film is formed around the voids in the drying process to form independent voids. Therefore, the content of the water-soluble cellulose derivative is based on the dry mass, and is a porous membrane. 5 mass% or less of a layer is preferable, More preferably, it is 3 mass% or less.
  • various polymer binders can be used in combination in order to improve the binding between the inorganic fine particles or between the porous support and the inorganic fine particles.
  • a binder it is preferable to use a latex polymer binder.
  • the polymer binder polyolefin (polyolefin), styrene-butadiene, acrylic, or the like can be used.
  • the content of the polymer binder is preferably 0.5 to 20% by mass, more preferably 1 to 8% by mass based on the dry mass.
  • the content of the inorganic fine particles used in addition to the predetermined aluminum oxide-based composite is preferably 80% by mass or less, more preferably 60% by mass of the porous membrane layer on a dry mass basis. % Or less.
  • a porous support is used together with the porous membrane layer.
  • the porous support include a porous film, a woven fabric, a nonwoven fabric, and a knitted fabric.
  • the material for the porous support include polyester, polyolefin, polyamide, aramid, and cellulose.
  • the porous support is preferably a nonwoven fabric using fibers such as polyester, polyolefin, polyamide, aramid, and cellulose.
  • the nonwoven fabric is preferably a nonwoven fabric using a polyester or polyolefin fiber that is durable to an electrolyte and easily obtains fine fibers, and more preferably a nonwoven fabric using a polyester fiber excellent in heat resistance.
  • the nonwoven fabric can be produced by various methods such as a wet method, a dry method, and an electrostatic spinning method.
  • the thickness of the porous support is preferably 5 ⁇ m or more, more preferably 8 ⁇ m or more, further preferably 10 ⁇ m or more, and particularly preferably 12 ⁇ m or more.
  • the thickness of the porous support is preferably 25 ⁇ m or less, more preferably 18 ⁇ m or less, still more preferably 16 ⁇ m or less, and particularly preferably 15 ⁇ m or less.
  • the porosity of the porous support is preferably 30 to 80%. It is more preferably 40 to 80%, further preferably 50 to 80%, and particularly preferably 55 to 70%.
  • the thickness is preferably 8 to 16 ⁇ m and the porosity is preferably 50 to 80%, more preferably 10 to 15 ⁇ m and the porosity is 55 to 70%.
  • the porous membrane layer can be formed by coating or impregnating a porous support with a coating solution of inorganic fine particles and drying.
  • the coating liquid may be gelled before drying.
  • the coating or impregnation method include an air doctor coater, a blade coater, a blade coater, a rod coater, a squeeze coater, and an impregnation coater (dip). coater), gravure coater, kiss roll coater (kiss roll coater), die coater (die coater), reverse roll coater (reverse roll coater), transfer roll coater (transfer roll coater), spray coater (spray coater) It is possible to use a method using That.
  • the coating amount of the porous membrane layer is preferably 0.5 to 50 g / m 2 in terms of dry mass, more preferably 0.5 to 30 g / m 2 , and 1 to 30 g / m 2 . Is more preferable, 1.0 to 15 g / m 2 is particularly preferable, and 3 to 12 g / m 2 is most preferable. It is also possible to adjust the thickness of the battery separator by performing calendar treatment or thermal calendar treatment after drying.
  • the thickness of the battery separator is preferably 10 ⁇ m or more, more preferably 12 ⁇ m or more, and still more preferably 18 ⁇ m or more.
  • the thickness of the battery separator is preferably 30 ⁇ m or less.
  • the thin film separator is more preferably 25 ⁇ m or less, further preferably 22 ⁇ m or less, particularly preferably about 20 ⁇ m in thickness (19 to 21 ⁇ m), and may be about 20 ⁇ m or less.
  • the battery separator is cut and sandwiched between electrode materials for a lithium secondary battery, an electrolyte is injected, the battery is sealed, and a lithium secondary battery is obtained.
  • the material constituting the positive electrode is mainly an active material, a conductive agent such as carbon black, and a binder such as polyvinylidene fluoride and styrene-butadiene rubber (SBR).
  • the active material includes lithium cobaltate and lithium nickelate. Lithium manganate, nickel manganese lithium cobalt oxide (NMC), lithium manganese manganate such as lithium aluminum manganate (AMO), lithium iron phosphate and the like are used. These are mixed and applied onto an aluminum foil as a current collector to form a positive electrode.
  • the material constituting the negative electrode is mainly an active material, a conductive agent, and a binder, and graphite, amorphous carbon material, silicon, lithium, lithium alloy, etc. are used as the active material. These are mixed and applied onto a copper foil as a current collector to form a negative electrode.
  • a separator is sandwiched between a positive electrode and a negative electrode, and an electrolytic solution is impregnated therein to provide ionic conductivity and conduct.
  • a non-aqueous electrolyte is used.
  • the non-aqueous electrolyte is composed of a solvent and a supporting electrolyte.
  • the solvent for example, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and vinylene carbonate having an additive function, Carbonate such as vinyl ethylene carbonate. Dimethoxyethane (DME) can also be used.
  • an organic lithium salt such as LiN (SO 2 CF 3 ) 2 is also used.
  • Ionic liquids can also be used.
  • a metal cylindrical can such as aluminum or stainless steel, a rectangular can, a sheet-type exterior body using a laminate film obtained by laminating aluminum foil with polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, or the like can be used. Further, it can be used by stacking and stacking, or it can be used by rotating in a cylindrical shape.
  • ⁇ Synthesis of aluminum oxide composite 40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.4 ⁇ m. To this slurry, 0.4 g (0.01 mol) of sodium hydroxide (NaOH) was added and stirred well, then heated at 300 ° C. for 2 hours in a hydrothermal state, with an average particle size of 1.2 ⁇ m, thickness A plate-like aluminum oxide composite 1 (composite 1) having a thickness of 100 nm and AlO 0.9 (OH) 1.2 was synthesized.
  • composite 1 composite 1 having a thickness of 100 nm and AlO 0.9 (OH) 1.2 was synthesized.
  • the composite 1 was heated in the atmosphere at 430 ° C. for 6 hours to obtain an aluminum oxide-based composite 2 (composite 2) of AlO 1.05 (OH) 0.9 .
  • the composite 1 was heated in air at 450 ° C. for 6 hours to obtain an aluminum oxide-based composite 3 (complex 3) of AlO 1.2 (OH) 0.6 .
  • the complex 1 was heated in the atmosphere at 460 ° C. for 4 hours to obtain an aluminum oxide complex 4 (complex 4) having AlO 1.3 (OH) 0.4 .
  • the composite 1 was heated in the atmosphere at 470 ° C. for 3 hours to obtain an aluminum oxide-based composite 5 (complex 5) of AlO 1.4 (OH) 0.2 .
  • Body 6 was obtained.
  • Example 1-1 The following materials were stirred with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed: 1500 rpm) for 3 hours to prepare dispersion (1).
  • a homogenizer manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed: 1500 rpm
  • Dispersion (1) 100 parts by weight of sodium carboxymethylcellulose aqueous solution (made by Nippon Paper Industries, trade name: MAC500LC) and 100 parts by weight of acrylic latex (JSR, trade name: TRD202A) 6 parts by mass of 40.2% by mass) was added to prepare a coating liquid (1).
  • Stretched regular polyethylene terephthalate (PET) fiber (0.1 dtex, length 5 mm) 30 parts by mass, stretched regular PET fiber (0.3 dtex, length 5 mm) 40 parts by mass, unstretched PET fiber (0.2 dtex, length 4 mm) )
  • a web having a weight per unit area of 9.5 g / m 2 was prepared by a wet method with a composition of 30 parts by mass. The drying temperature at this time was 130 ° C.
  • a thermal calendar process was performed at 190 ° C. to prepare a porous support (1) having a thickness of 15 ⁇ m.
  • the porous support (1) was impregnated with the coating liquid (1) and then dried at 100 ° C. to obtain a separator having a coating amount of 11 g / m 2 and a thickness of 24 ⁇ m.
  • Example 1-2 Using composite 3 instead of composite 2 in Example 1-1, a separator having a coating amount of 11 g / m 2 and a thickness of 24 ⁇ m was obtained.
  • Example 1-3 Using the composite 4 instead of the composite 2 in Example 1-1, a separator having a coating amount of 12 g / m 2 and a thickness of 24 ⁇ m was obtained.
  • Comparative Example 1-1 A composite separator 1 was used instead of the composite 2 in Example 1-1 to obtain a comparative separator having a coating amount of 11 g / m 2 and a thickness of 24 ⁇ m.
  • Comparative Example 1-2 The composite 5 was used in place of the composite 2 in Example 1-1 to obtain a comparative separator having a coating amount of 12 g / m 2 and a thickness of 24 ⁇ m.
  • Comparative Example 1-3 Using the composite 6 instead of the composite 2 in Example 1-1, a comparative separator having a coating amount of 12 g / m 2 and a thickness of 24 ⁇ m was obtained.
  • Comparative Example 1-4 Using the composite 7 instead of the composite 2 in Example 1-1, a comparative separator having a coating amount of 14 g / m 2 and a thickness of 24 ⁇ m was obtained.
  • the lithium secondary battery was produced by sealing in an aluminum foil laminate film. Next, the lithium secondary battery was charged to 4.2 V at 0.2 C, and a voltage drop value was obtained from the voltage 30 minutes after the start of discharge under the condition of 0.2 C (discharge time of 300 minutes). The internal resistance was measured from the fall value. Furthermore, the charge / discharge at 1C was repeated 100 times, and the ratio of the 100th discharge capacity to the first discharge capacity (capacity maintenance ratio) was measured. The results are shown in Table 1.
  • the membrane resistance and the internal resistance of the battery were low, and the battery capacity reduction was suppressed even during repeated use, and a battery separator excellent in durability was obtained.
  • ⁇ Synthesis of aluminum oxide composite > 70 g (0.504 mol) of ammonium aluminum carbonate (NH 4 AlCO 3 (OH) 2 , formula weight 139) and 100 g of water were mixed and wet-pulverized with a bead mill to prepare a slurry having an average particle size of 0.5 ⁇ m. This was heated at 160 ° C. for 12 hours in a hydrothermal state to synthesize a granular aluminum oxide composite 8 having an average particle diameter of 1.0 ⁇ m and AlO 1.1 (OH) 0.8 . The X-ray diffraction spectrum of the aluminum oxide composite 8 was measured and shown in FIG.
  • the peak intensity P1 is larger than the peak intensity P2 (P1> P2).
  • Example 2-1 The following material was stirred for 3 hours with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed 1500 rpm) to prepare dispersion (2).
  • a homogenizer manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed 1500 rpm
  • Dispersion (2) 100 parts by mass, 0.6 mass% sodium carboxymethylcellulose aqueous solution (Nippon Paper Industries, trade name: MAC500LC) 50 parts by mass and acrylic latex (JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (2).
  • Stretched regular PET fiber (0.1 dtex, length 5 mm) 30 parts by mass, stretched regular PET fiber (0.3 dtex, length 5 mm) 40 parts by mass, unstretched PET fiber (0.2 dtex, length 4 mm) 30 parts by mass
  • a web having a weight per unit area of 8.0 g / m 2 was prepared by a wet method. The drying temperature at this time was 130 ° C.
  • a thermal calendar process was performed at 190 ° C. to prepare a porous support (2) having a thickness of 15 ⁇ m. After impregnating the coating liquid (2) into the porous support (2), it was dried at 100 ° C. to obtain a separator having a coating amount of 9.0 g / m 2 and a thickness of 22 ⁇ m.
  • Dispersion (3) 100 parts by mass, 50 parts by mass of 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (3).
  • the porous support (2) was impregnated with the coating liquid (3) and then dried at 100 ° C. to obtain a separator having a coating amount of 9.0 g / m 2 and a thickness of 22 ⁇ m.
  • the lithium secondary battery was produced by sealing in an aluminum foil laminate film. Next, the lithium secondary battery was charged to 4.2 V at 0.2 C, and a voltage drop value was obtained from the voltage 30 minutes after the start of discharge under the condition of 0.2 C (discharge time of 300 minutes). The internal resistance was measured from the fall value. Moreover, the discharge capacity and charge capacity in 1C were measured, and the first discharge efficiency (discharge capacity / charge capacity ⁇ 100) was measured. Furthermore, after heating the battery at 80 ° C. for 24 hours, the discharge capacity and charge capacity at 1C were measured, and the discharge efficiency after heating was measured. The results are shown in Table 2.
  • Example 2-1 and Comparative Example 2-1 a thin film separator having a thickness of 22 ⁇ m was obtained.
  • the battery using the separator of Example 2-1 using the aluminum oxide-based composite 8 having P2 larger than P1 (P1 ⁇ P2) has a P2 smaller than P1 (P1> P2).
  • the internal resistance was lower than that of the battery using the separator of Comparative Example 2-1 using the system composite 9, and the decrease in discharge efficiency due to heating was suppressed.
  • ⁇ Synthesis of aluminum oxide composite 40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.3 ⁇ m. After adding 0.4 g (0.01 mol) of sodium hydroxide to this slurry and stirring well, it was heated in a hydrothermal state at 160 ° C. for 2 hours to obtain an average particle size of 1.0 ⁇ m, AlO 0.9 ( OH) An aluminum oxide composite 10 of 1.2 was synthesized. Next, the aluminum oxide composite 10 is heated at 430 ° C. for 6 hours, and a granular aluminum oxide composite 11 (composite having an average particle diameter of 1.0 ⁇ m and AlO 1.05 (OH) 0.9 ) is obtained. Body 11) was obtained.
  • the aluminum oxide-based composite 10 is heated at 470 ° C. for 6 hours to form a granular aluminum oxide-based composite 13 (composite 13) having an average particle diameter of 1.0 ⁇ m and AlO 1.2 (OH) 0.6.
  • composite 13 granular aluminum oxide-based composite 13 having an average particle diameter of 1.0 ⁇ m and AlO 1.2 (OH) 0.6.
  • Example 3-1 The following materials were stirred for 3 hours with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed: 1500 rpm) to prepare dispersion (4).
  • a homogenizer manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed: 1500 rpm
  • Dispersion (4) 100 parts by mass, 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, density 40.2) 3% by mass) was added to prepare a coating liquid (4).
  • the average particle diameter of the composite 11 was 1.0 ⁇ m as in the synthesis.
  • the porous support (2) was impregnated with the coating liquid (4) and then dried at 100 ° C. to obtain a separator having a coating amount of 9.0 g / m 2 and a thickness of 22 ⁇ m.
  • Example 3-2 A separator having a thickness of 21 ⁇ m was obtained in the same manner as in Example 3-1, except that the coating amount was 7.0 g / m 2 .
  • Example 3-3 A separator having a thickness of 20 ⁇ m was obtained in the same manner as in Example 3-1, except that the coating amount was 6.0 g / m 2 .
  • Example 3-4 The following materials were stirred for 2 hours with a bead mill to prepare dispersion (5).
  • Dispersion (5) 100 parts by mass, 50 parts by mass of a 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (5).
  • the average particle size of the composite 12 was 1.0 ⁇ m.
  • the porous support (2) was impregnated with the coating liquid (5) and then dried at 100 ° C. to obtain a separator having a coating amount of 7.0 g / m 2 and a thickness of 21 ⁇ m.
  • Example 3-5 The following materials were stirred with a bead mill for 12 hours to prepare dispersion (6).
  • Dispersion (6) 50 parts by mass of 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries Co., Ltd., trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (6).
  • the average particle size of the composite 12 was 0.6 ⁇ m.
  • the porous support (2) was impregnated with the coating liquid (6) and then dried at 100 ° C. to obtain a separator having a coating amount of 5.8 g / m 2 and a thickness of 20 ⁇ m.
  • Example 3-6 The following materials were stirred with a bead mill for 24 hours to prepare dispersion (7).
  • Dispersion (7) 50 parts by mass of 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries Co., Ltd., trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (7).
  • the average particle size of the composite 12 was 0.3 ⁇ m.
  • the porous support (2) was impregnated with the coating liquid (7) and then dried at 100 ° C. to obtain a separator having a coating amount of 4.5 g / m 2 and a thickness of 19 ⁇ m.
  • Example 3--7 The following materials were stirred with a bead mill for 24 hours to prepare dispersion (8).
  • Dispersion (8) 100 parts by mass, 0.6 mass% sodium carboxymethylcellulose aqueous solution (Nippon Paper Industries, trade name: MAC500LC) 50 parts by mass and acrylic latex (JSR, trade name: TRD202A, concentration 40.2) 3 parts by mass) was added to prepare a coating liquid (8).
  • the average particle size of the composite 12 was 0.2 ⁇ m.
  • the porous support (2) was impregnated with the coating liquid (8) and then dried at 100 ° C. to obtain a separator having a coating amount of 4.5 g / m 2 and a thickness of 19 ⁇ m.
  • Example 3-8 A separator having a thickness of 21 ⁇ m was obtained in the same manner as in Example 3-1, except that the composite 3 was used instead of the composite 1 and the coating amount was 9.0 g / m 2 .
  • Example 3-9 The following material was stirred for 3 hours with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed 1500 rpm) to prepare a dispersion (9).
  • a homogenizer manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed 1500 rpm
  • Dispersion (9) in 100 parts by mass, 50 parts by mass of a 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3 parts by mass) was added to prepare a coating liquid (1).
  • the average particle diameter of the composite 2 was 2.2 ⁇ m as in the synthesis.
  • the porous support (2) was impregnated with the coating liquid (9) and dried at 100 ° C. to obtain a separator having a coating amount of 15.0 g / m 2 and a thickness of 27 ⁇ m.
  • Example 3-10 A separator having a thickness of 24 ⁇ m was obtained in the same manner as in Example 3-9 except that the coating amount was 9.0 g / m 2 .
  • Example 3-11 A separator having a thickness of 22 ⁇ m was obtained in the same manner as in Example 3-9 except that the coating amount was 7.0 g / m 2 .
  • Example 3-1 A separator having a thickness of 20 ⁇ m was obtained in the same manner as in Example 3-9, except that the composite 14 was used instead of the composite 12 and the coating amount was 6.0 g / m 2 .
  • a separator having a thickness of 19 ⁇ m was obtained in the same manner as in Example 3-9, except that the composite 15 was used in place of the composite 2 and the coating amount was 4.5 g / m 2 .
  • the lithium secondary battery was produced by sealing in an aluminum foil laminate film. Next, the lithium secondary battery was charged to 4.2 V at 0.2 C, and a voltage drop value was obtained from the voltage 30 minutes after the start of discharge under the condition of 0.2 C (discharge time of 300 minutes). The internal resistance was measured from the fall value. Moreover, the discharge capacity and charge capacity in 1C were measured, and the first discharge efficiency (discharge capacity / charge capacity ⁇ 100) was measured. Furthermore, after heating the battery at 80 ° C. for 24 hours, the discharge capacity and charge capacity at 1C were measured, and the discharge efficiency after heating was measured. The results are shown in Table 3. The average pore diameter of each separator was measured and shown in Table 3.
  • the average pore diameter increased and the discharge efficiency decreased.
  • a coating amount of 15 g / m 2 is required as in Example 3-9. In that case, the thickness of the separator is 27 ⁇ m, and it is necessary to reduce the thickness of the battery. It was difficult to respond.
  • Comparative Example 3-1 the average particle size of the inorganic fine particles is 0.6 ⁇ m, and in Comparative Example 3-2, the average particle size of the inorganic fine particles is 0.2 ⁇ m. Therefore, in both cases, a separator having a thickness of 20 ⁇ m or less was obtained, and the initial discharge efficiency was 90%, and there was no problem.
  • x is 1.0 or less (x ⁇ 1.0) and y is 1.0 or more (y ⁇ 1.0)
  • the battery characteristics are significantly deteriorated by heating due to excessive hydroxyl groups of the inorganic fine particles.
  • the discharge efficiency after heating decreased to 55% or less.
  • the coating amount was 6.0 g / m 2
  • the discharge efficiency was lowered as compared with Examples 3-1, 3-2 and 3-4. Therefore, it can be seen that the coating amount is preferably 7.0 g / m 2 or more in order to operate the battery more stably.
  • the thickness of the separator is 20 to 22 ⁇ m, and in Example 3-3 in which the coating amount is 6.0 g / m 2, it is 20 ⁇ m.
  • Example 3-5 an aluminum oxide composite having an average particle size of 0.6 ⁇ m was used, but the discharge efficiency was high and the internal resistance was small despite the coating amount being as low as 5.8 g / m 2. Therefore, the battery can be operated stably, and a thin film separator having a thickness of 20 ⁇ m can be manufactured.
  • the average particle diameter of the inorganic fine particles is further smaller, being 0.3 ⁇ m and 0.2 ⁇ m.
  • the coating amount was as small as 4.5 g / m 2 and the thickness of the separator was 19 ⁇ m, which could be further reduced. Since the average particle size of the inorganic fine particles was reduced, the filling rate of the inorganic fine particles was increased, and the internal resistance of the battery was slightly increased as compared with Examples 3-1 to 3-5. However, the initial discharge efficiency was as high as 90%, and the discharge efficiency after heating was also high.
  • Example 3-1 in which the amount of hydroxyl groups in the aluminum oxide-based composite is large is superior in lower internal resistance, and Example 3-8 in which the amount of hydroxyl groups is small is superior in discharge efficiency. It was.
  • the battery separator of the present invention can be used as a capacitor separator in addition to a lithium secondary battery separator.

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Abstract

This battery separator has a porous film layer comprising a porous support body and inorganic particles, and is characterized in that the inorganic particles are aluminum oxide-based composites represented by AlOx(OH)y (1.0<x≦1.3, 0.4≦y<1.0, and 2x+y=3) and obtained by hydrothermal synthesis. This battery separator results in low internal resistance of the battery and has excellent durability.

Description

電池用セパレータBattery separator
　本発明は、電池用セパレータに関するものである。 The present invention relates to a battery separator.
　従来、リチウム二次電池に使用されている電池用セパレータ（以下、「セパレータ」と略記する場合がある）としては、貫通した微細孔を有するポリオレフィンの多孔フィルムが用いられてきた。このセパレータは、電池が異常を起こして発熱した場合に、貫通した微細孔が溶融して閉塞し、電池の内部抵抗を高めることで、発熱を抑制し、電極剤であるコバルト酸リチウムの熱暴走による電池の爆発を抑制する仕組みを担ってきた。 Conventionally, as a battery separator (hereinafter sometimes abbreviated as a “separator”) used in a lithium secondary battery, a polyolefin porous film having through holes has been used. This separator suppresses heat generation by increasing the internal resistance of the battery when the battery generates heat due to abnormalities and melts and closes through the fine holes, and thermal runaway of lithium cobaltate, which is the electrode agent It has been responsible for suppressing the explosion of batteries.
　しかし、ハイブリッド自動車用電池や無停電電源など、大電流による充放電が必要な用途では、最近の研究によって、電極剤によって熱暴走爆発を抑制する技術も開発されている。しかしながら、電池内の温度がこれまで以上に急激に上昇する場合がある。その場合には、セパレータが熱収縮することによって電極間接触が発生し、熱暴走が発生し、電池が爆発する場合がある。この電極間接触を避けるために、耐熱性が高くて熱収縮が起こりにくく、かつ内部抵抗の小さなセパレータが要望されている。 However, in applications that require charging and discharging with a large current, such as hybrid vehicle batteries and uninterruptible power supplies, recent research has also developed a technology that suppresses thermal runaway explosions using electrode materials. However, the temperature in the battery may increase more rapidly than ever. In that case, contact between the electrodes occurs due to thermal contraction of the separator, thermal runaway occurs, and the battery may explode. In order to avoid this contact between electrodes, a separator having high heat resistance, hardly causing thermal contraction, and having low internal resistance is desired.
　この要望に対し、不織布などの孔の開いた多孔質支持体とセラミック材料による多孔質膜を複合させたセパレータが開示されている。このセパレータでは、多孔質セラミック材料によって耐熱性が付与されていて、電池の熱暴走が発生した場合でも、セパレータの熱収縮が起こりにくく、電極間接触が抑制される（例えば、特許文献１参照）。このセパレータでは、セラミック材料がセパレータの表面に存在すると共に、セパレータ内部にも浸透することによって、高い電解液の保持性や耐熱性を付与することが可能である。 In response to this demand, a separator is disclosed in which a porous support having a hole such as a nonwoven fabric and a porous film made of a ceramic material are combined. In this separator, heat resistance is imparted by the porous ceramic material, and even when a thermal runaway of the battery occurs, thermal contraction of the separator hardly occurs and contact between the electrodes is suppressed (for example, see Patent Document 1). . In this separator, the ceramic material is present on the surface of the separator and also penetrates into the separator, so that it is possible to impart high electrolyte retention and heat resistance.
　また、多孔性のフィルムの片面に無機層を設けることによって、耐熱性が付与されたセパレータも提案されている（例えば、特許文献２及び３参照）。 Also, a separator to which heat resistance is imparted by providing an inorganic layer on one side of a porous film has been proposed (see, for example, Patent Documents 2 and 3).
　セラミック材料による多孔質膜や無機層は、アルミニウム酸化物、ジルコニウム酸化物、ケイ素酸化物、酸化チタン、チタン酸バリウム、チタン酸鉛、チタン酸ストロンチウムなどの酸化チタン及びその複合酸化物等の無機微粒子を含有することが一般的である。この中でも、アルミニウム酸化物は、最も頻繁に使用される無機微粒子の１つである。 Porous membranes and inorganic layers made of ceramic materials include aluminum oxide, zirconium oxide, silicon oxide, titanium oxide, barium titanate, lead titanate, strontium titanate and other inorganic fine particles such as titanium oxide and composite oxides thereof. It is common to contain. Among these, aluminum oxide is one of the most frequently used inorganic fine particles.
　アルミニウム酸化物のうち、水熱合成によって得られる水酸化酸化アルミニウム（ＡｌＯＯＨ）は、水熱合成時の条件によって、板状、粒状、針状等の種々の形態を得ることができ、凝集構造が特異的で大きな内部空間を形成でき、かつ、リチウム二次電池用電解液に対する濡れ性にも優れており、特に好ましい材料である。しかしながら、原料の水酸化アルミニウムに由来する構造水などによって、電解液に対する耐久性に問題があり、繰り返し充放電を行った際の耐久性に問題が生じる場合があった（例えば、特許文献４～６参照）。 Among aluminum oxides, aluminum hydroxide oxide (AlOOH) obtained by hydrothermal synthesis can be obtained in various forms such as plate-like, granular, and needle-like, depending on the conditions during hydrothermal synthesis. It is a particularly preferable material because it can form a specific and large internal space and has excellent wettability with respect to an electrolyte for a lithium secondary battery. However, due to structural water derived from the raw material aluminum hydroxide, there is a problem in durability with respect to the electrolytic solution, and there may be a problem in durability when repeated charging and discharging are performed (for example, Patent Documents 4 to 4). 6).
　さらに、従来のセパレータの厚さは３０μｍ程度であったが、近年ではセパレータの薄膜化の要望が強く、厚さ２５μｍ以下の薄膜化セパレータが必要となっていて、さらには、厚さ２０μｍ程度又はそれ以下のセパレータも要望されている。このために、セパレータに用いられるアルミニウム酸化物にも、粒子形状やサイズに制約が出てきている。粒子のサイズが小さくなって、アルミニウム酸化物の充填構造が密になりすぎると、セパレータの内部抵抗が高くなることもある。従来のアルミニウム酸化物では、電解液に対する耐久性、低内部抵抗、セパレータの薄膜化という課題をすべて満たすことは容易ではなかった。 Furthermore, although the thickness of the conventional separator was about 30 μm, in recent years, there has been a strong demand for thinning the separator, and a thinned separator having a thickness of 25 μm or less is required. Lesser separators are also desired. For this reason, restrictions have been placed on the particle shape and size of the aluminum oxide used in the separator. If the particle size is reduced and the aluminum oxide filling structure becomes too dense, the internal resistance of the separator may increase. With conventional aluminum oxides, it has not been easy to satisfy all of the problems of durability against electrolyte, low internal resistance, and thinning of the separator.
特許第４５９４０９８号公報Japanese Patent No. 4594098 特表２００８－５０３０４９号公報Special table 2008-503049 gazette 特許第４４９９８５１号公報Japanese Patent No. 4499851 特許第４４２６７２１号公報Japanese Patent No. 4426721 国際公開第２００８／１１４７２７号パンフレットInternational Publication No. 2008/114727 Pamphlet 特開２０１３－２５４６７７号公報JP 2013-254677 A
　本発明の課題は、アルミニウム酸化物を用いた電池用セパレータにおいて、電解液に対する耐久性に優れ、セパレータの薄膜化の要望にも対応でき、電池の内部抵抗を低くすることもできる電池用セパレータを提供することである。 An object of the present invention is to provide a battery separator that uses aluminum oxide, has excellent durability against electrolytes, can meet the demand for thinning the separator, and can reduce the internal resistance of the battery. Is to provide.
　下記に示す本発明によって、上記課題を解決できることが見出された。 It has been found that the above-described problems can be solved by the present invention described below.
（１）多孔性支持体と無機微粒子を含有してなる多孔質膜層を有する電池用セパレータにおいて、該無機微粒子が、水熱合成によって得られたＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）で示されるアルミニウム酸化物系複合体であることを特徴とする電池用セパレータ。
（２）該無機微粒子のＸ線回折による２θ＝１４．４°のピーク強度（Ｐ１）よりも、２θ＝２８．２°のピーク強度（Ｐ２）が大きい（Ｐ１＜Ｐ２）、上記（１）記載の電池用セパレータ。
（３）該無機微粒子の平均粒子径が０．２～１．０μｍである、上記（１）又は（２）記載の電池用セパレータ。 (1) In a battery separator having a porous support and a porous membrane layer containing inorganic fine particles, the inorganic fine particles are obtained by hydrothermal synthesis of AlO x (OH) y (1.0 <x ≦ 1.3, 0.4 ≦ y <1.0, 2x + y = 3) A battery separator characterized by being an aluminum oxide composite.
(2) The peak intensity (P2) at 2θ = 28.2 ° is larger than the peak intensity (P1) at 2θ = 14.4 ° by X-ray diffraction of the inorganic fine particles (P1 <P2), the above (1) The battery separator as described.
(3) The battery separator according to (1) or (2), wherein the inorganic fine particles have an average particle size of 0.2 to 1.0 μm.
　本発明では、アルミニウム酸化物を用いた電池用セパレータにおいて、電解液に対する耐久性に優れ、セパレータの薄膜化の要望にも対応でき、電池の内部抵抗を低くすることもできる電池用セパレータを提供することができる。 The present invention provides a battery separator using an aluminum oxide, which has excellent durability against an electrolyte, can meet the demand for thinning the separator, and can reduce the internal resistance of the battery. be able to.
アルミニウム酸化物系複合体８のＸ線回折スペクトルである。2 is an X-ray diffraction spectrum of an aluminum oxide composite 8. アルミニウム酸化物系複合体９のＸ線回折スペクトルである。2 is an X-ray diffraction spectrum of an aluminum oxide composite 9.
　本発明の電池用セパレータは、多孔性支持体と無機微粒子を含有してなる多孔質膜層を有する電池用セパレータであり、該無機微粒子が、水熱合成によって得られたＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）で示されるアルミニウム酸化物系複合体であることを特徴とする。 The battery separator of the present invention is a battery separator having a porous film layer containing a porous support and inorganic fine particles, and the inorganic fine particles are AlO x (OH) y obtained by hydrothermal synthesis. It is an aluminum oxide based composite represented by (1.0 <x ≦ 1.3, 0.4 ≦ y <1.0, 2x + y = 3).
　水熱合成によって得られるアルミニウム酸化物系複合体は、ＡｌＯｘ（ＯＨ）ｙ（０＜ｘ＜１．５、０＜ｙ＜３、２ｘ＋ｙ＝３）である。このうち、水酸化アルミニウム構造が主であると、電解液への耐久性が劣り、１５０℃程度で容易に水を放出するので、電池中の電解液の加水分解を促進して、電池特性悪化の要因となる。反対に、酸化アルミニウムの構造が主となると、電解液の塗れ性が低下して、電池の内部抵抗が上昇してくる。本発明において、無機微粒子として使用されるアルミニウム酸化物系複合体は、ＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）であり、より好ましくは、ＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．２、０．６≦ｙ＜１．０、２ｘ＋ｙ＝３）である。 The aluminum oxide composite obtained by hydrothermal synthesis is AlO x (OH) y (0 <x <1.5, 0 <y <3, 2x + y = 3). Among these, when the aluminum hydroxide structure is the main, the durability to the electrolytic solution is inferior, and water is easily released at about 150 ° C., so the hydrolysis of the electrolytic solution in the battery is promoted and the battery characteristics deteriorate. It becomes a factor of. On the other hand, when the structure of aluminum oxide is main, the wettability of the electrolytic solution is lowered and the internal resistance of the battery is increased. In the present invention, the aluminum oxide composite used as the inorganic fine particles is AlO x (OH) y (1.0 <x ≦ 1.3, 0.4 ≦ y <1.0, 2x + y = 3). Yes, and more preferably AlO x (OH) y (1.0 <x ≦ 1.2, 0.6 ≦ y <1.0, 2x + y = 3).
　アルミニウム酸化物系複合体の酸素／アルミニウム元素比率は、エネルギー分散型Ｘ線分光（ＥＤＳ）によって測定される。この測定方法は、電子線により励起した元素が特定のＸ線を放出する原理を利用したもので、測定精度５％以下で、酸素／アルミニウムの元素比率を同時に測定できる優れた方法である。一般的に、走査型電子顕微鏡（ＳＥＭ）に専用の分光装置を付加して測定可能で、電子線の資料への浸透距離も数μｍ程度あるので、観察検体のほぼ平均的な元素比率を得られ、再現性の高い分析方法である。 The oxygen / aluminum element ratio of the aluminum oxide composite is measured by energy dispersive X-ray spectroscopy (EDS). This measurement method utilizes the principle that an element excited by an electron beam emits a specific X-ray, and is an excellent method capable of simultaneously measuring the oxygen / aluminum element ratio with a measurement accuracy of 5% or less. In general, it can be measured by adding a special spectroscopic device to a scanning electron microscope (SEM), and the penetration distance of electron beam to the material is about several μm, so an almost average element ratio of the observed specimen can be obtained. The analysis method is highly reproducible.
　水熱合成の出発原料としては、水酸化アルミニウム、アンモニウムアルミニウム炭酸塩（Ａｍｍｏｎｉｕｍ　Ａｌｕｍｉｎｕｍ　Ｃａｒｂｏｎａｔｅ　Ｈｙｄｒｏｘｉｄｅ、ＡＡＣＨ）等が挙げられる。 Examples of starting materials for hydrothermal synthesis include aluminum hydroxide, ammonium aluminum carbonate (Ammonium Carbonate Hydroxide, AACH) and the like.
　一般的に、水酸化アルミニウム［Ａｌ（ＯＨ）３］を出発原料として１５０～２００℃で水熱合成を行うと、アルミニウム酸化物系複合体として、水酸化酸化アルミニウム［ＡｌＯ（ＯＨ）、鉱物名：ベーマイト（Ｂｏｅｈｍｉｔｅ）］が生成する。しかし、表面に存在する過剰の水酸基や原料の水酸化アルミニウムの微量残渣などにより、得られるアルミニウム酸化物系複合体は、ＡｌＯｘ（ＯＨ）ｙ（ｘ＜１．０、ｙ＞１．０、２ｘ＋ｙ＝３：酸素／アルミニウム元素比率で２．０以上）となる場合が多い。しかし、このアルミニウム酸化物系複合体が電池に入れられると、過剰な水酸基が電解液の加水分解を促進するので、好ましくない。そのため、この後に、電気炉などで加熱処理を施して、酸素／アルミニウム元素比率の再調整を行う。加熱温度は３５０～５００℃が好ましく、４００～４７０℃がより好ましい。しかし、加熱温度が４００℃未満の場合には反応速度が遅く、大量合成には不向きであり、また、加熱温度が４５０℃を超えると、次第に酸化アルミニウムに転位する場合があるので、さらに好ましい加熱温度は４００～４５０℃である。 In general, when hydrothermal synthesis is performed at 150 to 200 ° C. using aluminum hydroxide [Al (OH) 3 ] as a starting material, aluminum hydroxide oxide [AlO (OH), mineral name : Boehmite] is generated. However, due to excessive hydroxyl groups present on the surface, trace amounts of raw aluminum hydroxide, etc., the resulting aluminum oxide composite is AlO x (OH) y (x <1.0, y> 1.0, 2x + y = 3: the oxygen / aluminum element ratio is 2.0 or more in many cases. However, when this aluminum oxide-based composite is put in a battery, an excessive hydroxyl group promotes hydrolysis of the electrolytic solution, which is not preferable. Therefore, after this, heat treatment is performed in an electric furnace or the like to readjust the oxygen / aluminum element ratio. The heating temperature is preferably 350 to 500 ° C, more preferably 400 to 470 ° C. However, when the heating temperature is less than 400 ° C., the reaction rate is slow and unsuitable for large-scale synthesis, and when the heating temperature exceeds 450 ° C., it may be gradually rearranged to aluminum oxide. The temperature is 400-450 ° C.
　しかし、この加熱処理を経ると、表面の状態が不活性化して、アルミニウム酸化物系複合体微粒子の充填濃度が増加して、多孔質膜層の空隙が低下する場合があり、一般的に電池の内部抵抗が大きくなる場合がある。そのため、本発明では、水熱合成の出発原料としては、ＡＡＣＨを使用することが好ましい。ＡＡＣＨからは、２００℃程度の低温における水熱合成でも、アモルファスの酸化アルミニウム（Ａｌｕｍｉｎａ、アルミナ）が形成されることが知られており、水熱合成を行うと、ベーマイトに類似するＸ線回折構造を有しながら、ベーマイトとしては酸素欠損状態を有するアルミニウム酸化物系複合体となる。 However, when this heat treatment is performed, the surface state is inactivated, the packing concentration of the aluminum oxide composite fine particles is increased, and the voids of the porous membrane layer may be lowered. May increase the internal resistance. Therefore, in the present invention, it is preferable to use AACH as a starting material for hydrothermal synthesis. From AACH, it is known that amorphous aluminum oxide (Allumina) is formed even in hydrothermal synthesis at a low temperature of about 200 ° C. When hydrothermal synthesis is performed, an X-ray diffraction structure similar to boehmite is known. The boehmite is an aluminum oxide composite having an oxygen deficiency state.
　水酸化アルミニウムとしては、ギブサイトやバイヤライトなどの水酸化アルミニウムが挙げられる。また、アルミニウムアルコキシドなどの有機アルミニウム化合物を経由する高純度水酸化アルミニウムも使用できる。 Examples of aluminum hydroxide include aluminum hydroxide such as gibbsite and bayerite. Further, high-purity aluminum hydroxide via an organoaluminum compound such as aluminum alkoxide can also be used.
　アルミニウム酸化物系複合体の粒子形状を制御するために、アルカリ金属イオンやアンモニアを併用して合成してもよい。アンモニアの添加やナトリウム、カリウムイオンの微量添加では、立方体状や板状物が得られる。マグネシウムイオンの微量添加では、針状物などが得られる。さらに、水酸基やカルボン酸などを有する有機系化合物などを併用することによっても、異形粒子が得られる。原料となる水酸化アルミニウムやＡＡＣＨは、ボールミルなどの湿式分散機で予め粒度を調整して用いても良い。 In order to control the particle shape of the aluminum oxide-based composite, alkali metal ions or ammonia may be used in combination. When ammonia is added or a small amount of sodium or potassium ion is added, a cube or plate is obtained. When a small amount of magnesium ion is added, needles and the like are obtained. Furthermore, irregularly shaped particles can also be obtained by using together an organic compound having a hydroxyl group or a carboxylic acid. Aluminum hydroxide or AACH as a raw material may be used after adjusting the particle size in advance by a wet disperser such as a ball mill.
　本発明におけるアルミニウム酸化物系複合体では、Ｘ線回折による２θ＝１４．４°のピーク強度（Ｐ１）よりも、２θ＝２８．２°のピーク強度（Ｐ２）が大きい（Ｐ１＜Ｐ２）ことが好ましい。Ｘ線回折による結晶構造からの類推は難しいが、Ｐ１≧Ｐ２の構造は、水酸化アルミニウムを水熱合成して、ベーマイト化した時に現れ、この状態では、電解液中で加熱経時によって、電解液が変質する場合がある。しかし、Ｐ１＜Ｐ２ではこの変質が抑制されて、電解液中では安定となる。なお、Ｘ線回折強度は、アルミニウム酸化物系複合体をパウダー状として、ＰＡＮａｌｙｔｉｃａｌ社製Ｘ線回折強度測定装置「Ｘ’ＰｅｒｔＰＲＯ」で、線源はＣｕＫα線を用いて、測定した。 In the aluminum oxide composite according to the present invention, the peak intensity (P2) at 2θ = 28.2 ° is larger than the peak intensity (P1) at 2θ = 14.4 ° by X-ray diffraction (P1 <P2). Is preferred. Although it is difficult to infer from the crystal structure by X-ray diffraction, the structure of P1 ≧ P2 appears when aluminum hydroxide is hydrothermally synthesized to boehmite. In this state, the electrolyte solution May be altered. However, in P1 <P2, this alteration is suppressed and it becomes stable in the electrolytic solution. The X-ray diffraction intensity was measured using an X-ray diffraction intensity measuring apparatus “X'PertPRO” manufactured by PANalytical, using an aluminum oxide composite as a powder, and a CuKα ray as a radiation source.
　本発明における無機微粒子の平均粒子径は、好ましくは０．１～３．０μｍであり、より好ましくは０．１～１．５μｍであり、更に好ましくは０．２～１．０μｍである。平均粒子径は、無機微粒子を水で充分に希釈し、これをレーザー散乱タイプの粒度測定機（マイクロトラック（Ｍｉｃｒｏｔｒａｃ）社製、商品名：３３００ＥＸ２）によって測定して得られた中心粒子径（Ｄ５０、体積平均）である。平均粒子径が０．１～３．０μｍの無機微粒子が多孔質膜層に含まれることによって、内部空隙の大きな多孔質膜層を得られやすくなり、電池の内部抵抗を低下させることが容易になる。 The average particle size of the inorganic fine particles in the present invention is preferably 0.1 to 3.0 μm, more preferably 0.1 to 1.5 μm, and still more preferably 0.2 to 1.0 μm. The average particle size is obtained by sufficiently diluting the inorganic fine particles with water and measuring this with a laser scattering type particle size measuring device (trade name: 3300EX2 manufactured by Microtrac) (D50). , Volume average). By including inorganic fine particles having an average particle size of 0.1 to 3.0 μm in the porous membrane layer, it becomes easy to obtain a porous membrane layer having a large internal void, and it is easy to reduce the internal resistance of the battery. Become.
　電池を安定に動作させるためには、多孔質膜層が形成する平均細孔径は重要な要素である。特に、セパレータの平均細孔径が１．０μｍを超えると、内部短絡（内部ショート）を誘発して、放電容量の充電容量に対する比率が低下する、充電が不能となるなど、充放電特性が崩れる場合がある。そのため、多孔質膜層を形成する際には、平均細孔径をコントロールしながら、塗工量や厚さを調整することが必要である。これまでの知見から、多孔質膜層に用いる無機微粒子の平均粒子径が１．５μｍを超える場合は、最低でも１５ｇ／ｍ２程度の塗工量が必要である。この塗工量では、多孔性支持体の厚さを加えると、厚さが２０μｍ程度又はそれ以下の薄膜化セパレータを作製することは難しい。 In order to stably operate the battery, the average pore diameter formed by the porous membrane layer is an important factor. In particular, when the average pore size of the separator exceeds 1.0 μm, the internal short circuit (internal short circuit) is induced, the ratio of the discharge capacity to the charge capacity is reduced, or the charge / discharge characteristics are disrupted, such as the inability to charge. There is. Therefore, when forming the porous membrane layer, it is necessary to adjust the coating amount and thickness while controlling the average pore diameter. From the knowledge so far, when the average particle diameter of the inorganic fine particles used for the porous membrane layer exceeds 1.5 μm, a coating amount of at least about 15 g / m 2 is required. With this coating amount, when the thickness of the porous support is added, it is difficult to produce a thin film separator having a thickness of about 20 μm or less.
　無機微粒子の平均粒子径とセパレータの平均細孔径を詳細に検討した結果、厚さ２０μｍ程度又はそれ以下の薄膜化セパレータを得るためには、無機微粒子の平均粒子径が０．２～１．０μｍであることが好ましいことが見出された。この範囲であれば、安定した充放電特性が得られる。無機微粒子の平均粒子径は０．４～０．８μｍであることが特に好ましい。 As a result of examining the average particle diameter of the inorganic fine particles and the average pore diameter of the separator in detail, in order to obtain a thinned separator having a thickness of about 20 μm or less, the average particle diameter of the inorganic fine particles is 0.2 to 1.0 μm. It has been found that it is preferred. Within this range, stable charge / discharge characteristics can be obtained. The average particle size of the inorganic fine particles is particularly preferably 0.4 to 0.8 μm.
　本発明における平均細孔径はＰｏｒｏｕｓ　Ｍａｔｅｒｉａｌｓ　Ｉｎｃ．製Ｃａｐｉｉｌｌａｒｙ　Ｆｌｏｗ　Ｐｏｒｏｍｅｔｅｒ　ＣＥＰ－１５００Ａで測定した。 In the present invention, the average pore size is measured by Porous Materials Inc. Measurement was performed with a manufactured Capillary Flow Porometer CEP-1500A.
　水熱合成の出発原料としてＡＡＣＨを使用した場合に得られるアルミニウム酸化物系複合体は平均粒子径０．２μｍ程度の基本構造を有して、立方体に近い粒状構造を有している。このＡＡＣＨを出発原料としたアルミニウム酸化物系複合体は、湿式ビーズミル分散等で平均粒子径を容易にコントロールすることができるという特徴を有している点でも、水酸化アルミニウムを出発原料としたアルミニウム酸化物系複合体よりも好ましい。 The aluminum oxide composite obtained when AACH is used as a starting material for hydrothermal synthesis has a basic structure with an average particle diameter of about 0.2 μm and has a granular structure close to a cube. The aluminum oxide-based composite using AACH as a starting material is also characterized in that the average particle diameter can be easily controlled by wet bead mill dispersion or the like. It is preferable to the oxide-based composite.
　本発明の電池用セパレータは、無機微粒子の水系分散液又は溶剤系分散液である塗液を、多孔性支持体に塗工又は含浸させて、多孔質膜層を成形することによって製造される。この際、多孔質膜層には、高分子結着剤等が併用されても良い。 The battery separator of the present invention is manufactured by coating or impregnating a porous support with a coating liquid that is an aqueous dispersion or a solvent dispersion of inorganic fine particles, and forming a porous membrane layer. At this time, a polymer binder or the like may be used in combination with the porous membrane layer.
　水系分散液には、水溶性セルロース誘導体を含有させることが有効である。水溶性セルロース誘導体とは、グリコシド結合によって直鎖に結合したβ－グルコース分子の水酸基の一部を変性し、水溶化が可能として合成されたセルロース誘導体であって、水酸基の一部が、カルボキシメトキシ（ｃａｒｂｏｘｙｍｅｔｈｏｘｙ）基、メトキシ基（ｍｅｔｈｏｘｙ）、ヒドロキシエトキシ（ｈｙｄｒｏｘｙｅｔｈｏｘｙ）基、ヒドロキシプロポキシ（ｈｙｄｒｏｘｙｐｒｏｐｏｘｙ）基に変性されている化合物を示す。カルボキシメトキシ基で置換された誘導体はカルボキシメチルセルロース（ｃａｒｂｏｘｙｍｅｔｈｙｌｃｅｌｌｕｌｏｓｅ、ＣＭＣ）と呼ばれ、ナトリウム塩やアンモニウム塩等にして水溶性化できる。メトキシ基のみを含有するメチルセルロース（ｍｅｔｈｙｌｃｅｌｌｕｌｏｓｅ）は、低温水にのみ溶解し、温度が上昇すると、水溶液をゲル化する熱ゲル性を有する。また、起泡性・発泡性に優れており、ノニオン性の高分子界面活性剤的な挙動が得られる。一般的にメトキシ基に、ヒドロキシエトキシ基やヒドロキシプロポキシ基を組み合わせることによって、溶解性や熱ゲル性をコントロールすることができる。そのほか、水溶性カチオン化セルロースも用いることができる。しかし、酢酸セルロース（ａｃｅｔｙｌｃｅｌｌｕｌｏｓｅ）、エチルセルロース（ｅｔｈｙｌｃｅｌｌｕｌｏｓｅ）などのセルロース誘導体は、水には溶解しない非水溶性セルロース誘導体であるので、水系分散液には用いることが難しい。水溶性セルロース誘導体は、無機微粒子と併用されて、多孔質膜層を形成し、内部抵抗を低減化させることができる。水溶性セルロース誘導体の含有量が多すぎると、乾燥工程で空隙の周囲で成膜化して独立した空隙を形成してしまうので、水溶性セルロース誘導体の含有量は、乾燥質量基準で、多孔質膜層の５質量％以下が好ましく、より好ましくは３質量％以下である。 It is effective to contain a water-soluble cellulose derivative in the aqueous dispersion. A water-soluble cellulose derivative is a cellulose derivative synthesized by modifying a part of hydroxyl groups of β-glucose molecules bonded linearly by glycosidic bonds so as to be water-soluble. The compound modified | denatured by the (carboxy group) group, the methoxy group (methyoxy) group, the hydroxy ethoxy (hydroxyethoxy) group, and the hydroxypropoxy (hydroxypropoxy) group is shown. A derivative substituted with a carboxymethoxy group is called carboxymethylcellulose (CMC), and can be water-solubilized as a sodium salt or an ammonium salt. Methylcellulose containing only methoxy groups dissolves only in low-temperature water, and has a thermal gel property that gels an aqueous solution when the temperature rises. Moreover, it is excellent in foaming property and foaming property, and can behave like a nonionic polymer surfactant. In general, solubility and thermal gel properties can be controlled by combining a hydroxyethoxy group or a hydroxypropoxy group with a methoxy group. In addition, water-soluble cationized cellulose can also be used. However, since cellulose derivatives such as cellulose acetate and ethyl cellulose are water-insoluble cellulose derivatives that do not dissolve in water, it is difficult to use them in aqueous dispersions. The water-soluble cellulose derivative can be used in combination with inorganic fine particles to form a porous film layer and reduce internal resistance. If the content of the water-soluble cellulose derivative is too large, a film is formed around the voids in the drying process to form independent voids. Therefore, the content of the water-soluble cellulose derivative is based on the dry mass, and is a porous membrane. 5 mass% or less of a layer is preferable, More preferably, it is 3 mass% or less.
　さらに、無機微粒子間や、多孔性支持体と無機微粒子間の結着性を改善させるために、各種高分子結着剤を併用することができる。このような結着剤としては、ラテックス系の高分子結着剤を使用することが好ましい。高分子結着剤としては、ポリオレフィン（ｐｏｌｙｏｌｅｆｉｎ）系、スチレン－ブタジエン（ｓｔｙｒｅｎｅ－ｂｕｔａｄｉｅｎｅ）系、アクリル系などを用いることができる。高分子結着剤の含有量は、乾燥質量基準で、多孔質膜層の０．５～２０質量％が好ましく、より好ましくは１～８質量％である。 Furthermore, various polymer binders can be used in combination in order to improve the binding between the inorganic fine particles or between the porous support and the inorganic fine particles. As such a binder, it is preferable to use a latex polymer binder. As the polymer binder, polyolefin (polyolefin), styrene-butadiene, acrylic, or the like can be used. The content of the polymer binder is preferably 0.5 to 20% by mass, more preferably 1 to 8% by mass based on the dry mass.
　さらに、多孔質膜層の空隙を調整するために、複数の形状のアルミニウム酸化物系複合体や、他の金属酸化物、不溶性塩等の無機微粒子を併用することもできる。空隙を調整するために、所定のアルミニウム酸化物系複合体以外に併用される無機微粒子の含有量は、、乾燥質量基準で、多孔質膜層の８０質量％以下が好ましく、より好ましくは６０質量％以下である。 Furthermore, in order to adjust the voids of the porous membrane layer, a plurality of shapes of aluminum oxide composites, other metal oxides, inorganic fine particles such as insoluble salts can be used in combination. In order to adjust the voids, the content of the inorganic fine particles used in addition to the predetermined aluminum oxide-based composite is preferably 80% by mass or less, more preferably 60% by mass of the porous membrane layer on a dry mass basis. % Or less.
　本発明では、電池用セパレータとしての強度を向上させるために、多孔質膜層と共に、多孔性支持体を用いる。多孔性支持体としては、多孔フィルム、織布、不織布、編物等が挙げられる。多孔性支持体の材質としては、ポリエステル、ポリオレフィン、ポリアミド、アラミド、セルロース等を挙げることができる。多孔性支持体としては、ポリエステル、ポリオレフィン、ポリアミド、アラミド、セルロース等の繊維を用いた不織布であることが好ましい。電解液への耐久性があり、微細繊維の入手が容易なポリエステルやポリオレフィンの繊維を用いた不織布であることがより好ましく、耐熱性に優れたポリエステル繊維を用いた不織布が更に好ましい。不織布は、湿式法、乾式法、静電紡糸法等の各種方法で製造することができる。 In the present invention, in order to improve the strength as a battery separator, a porous support is used together with the porous membrane layer. Examples of the porous support include a porous film, a woven fabric, a nonwoven fabric, and a knitted fabric. Examples of the material for the porous support include polyester, polyolefin, polyamide, aramid, and cellulose. The porous support is preferably a nonwoven fabric using fibers such as polyester, polyolefin, polyamide, aramid, and cellulose. The nonwoven fabric is preferably a nonwoven fabric using a polyester or polyolefin fiber that is durable to an electrolyte and easily obtains fine fibers, and more preferably a nonwoven fabric using a polyester fiber excellent in heat resistance. The nonwoven fabric can be produced by various methods such as a wet method, a dry method, and an electrostatic spinning method.
　多孔性支持体の厚さは、５μｍ以上であることが好ましく、８μｍ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く、１２μｍ以上であることが特に好ましい。また、多孔性支持体の厚さは、２５μｍ以下であることが好ましく、１８μｍ以下であることがより好ましく、１６μｍ以下であることが更に好ましく、１５μｍ以下であることが特に好ましい。多孔性支持体の空隙率は、３０～８０％であることが好ましい。４０～８０％であることがより好ましく、５０～８０％であることが更に好ましく、５５～７０％であることが特に好ましい。薄膜化セパレータのためには、厚さ８～１６μｍ、空隙率５０～８０％であることが好ましく、厚さ１０～１５μｍ、空隙率５５～７０％であることがより好ましい。 The thickness of the porous support is preferably 5 μm or more, more preferably 8 μm or more, further preferably 10 μm or more, and particularly preferably 12 μm or more. The thickness of the porous support is preferably 25 μm or less, more preferably 18 μm or less, still more preferably 16 μm or less, and particularly preferably 15 μm or less. The porosity of the porous support is preferably 30 to 80%. It is more preferably 40 to 80%, further preferably 50 to 80%, and particularly preferably 55 to 70%. For a thin film separator, the thickness is preferably 8 to 16 μm and the porosity is preferably 50 to 80%, more preferably 10 to 15 μm and the porosity is 55 to 70%.
　多孔質膜層は、無機微粒子の塗液を、多孔性支持体に塗工又は含浸させ、乾燥させて形成することができる。場合によっては、乾燥前に塗液をゲル化させても良い。塗工又は含浸の方法としては、エアドクターコーター（ａｉｒ　ｄｏｃｔｏｒ　ｃｏａｔｅｒ）、ブレードコーター（ｂｌａｄｅ　ｃｏａｔｅｒ）、ナイフコーター（ｋｎｉｆｅ　ｃｏａｔｅｒ）、ロッドコーター（ｒｏｄ　ｃｏａｔｅｒ）、スクイズコーター（ｓｑｕｅｅｚｅ　ｃｏａｔｅｒ）、含浸コーター（ｄｉｐ　ｃｏａｔｅｒ）、グラビアコーター（ｇｒａｖｕｒｅ　ｃｏａｔｅｒ）、キスロールコーター（ｋｉｓｓ　ｒｏｌｌ　ｃｏａｔｅｒ）、ダイコーター（ｄｉｅ　ｃｏａｔｅｒ）、リバースロールコーター（ｒｅｖｅｒｓｅ　ｒｏｌｌ　ｃｏａｔｅｒ）、トランスファーロールコーター（ｔｒａｎｓｆｅｒ　ｒｏｌｌ　ｃｏａｔｅｒ）、スプレーコーター（ｓｐｒａｙ　ｃｏａｔｅｒ）等を用いた方法を使用することができる。 The porous membrane layer can be formed by coating or impregnating a porous support with a coating solution of inorganic fine particles and drying. In some cases, the coating liquid may be gelled before drying. Examples of the coating or impregnation method include an air doctor coater, a blade coater, a blade coater, a rod coater, a squeeze coater, and an impregnation coater (dip). coater), gravure coater, kiss roll coater (kiss roll coater), die coater (die coater), reverse roll coater (reverse roll coater), transfer roll coater (transfer roll coater), spray coater (spray coater) It is possible to use a method using That.
　多孔質膜層の塗工量は、乾燥質量で０．５～５０ｇ／ｍ２であることが好ましく、０．５～３０ｇ／ｍ２であることがより好ましく、１～３０ｇ／ｍ２であることが更に好ましく、１．０～１５ｇ／ｍ２であることが特に好ましく、３～１２ｇ／ｍ２であることが最も好ましい。乾燥後にカレンダー処理や熱カレンダー処理を施して、電池用セパレータの厚さを調整することも可能である。電池用セパレータの厚さは、１０μｍ以上が好ましく、１２μｍ以上がより好ましく、１８μｍ以上が更に好ましい。また、電池用セパレータの厚さは、３０μｍ以下が好ましい。薄膜化セパレータとしては、２５μｍ以下がより好ましく、２２μｍ以下が更に好ましく、厚さ２０μｍ程度（１９～２１μｍ）であることが特に好ましく、厚さ２０μｍ程度以下であっても良い。 The coating amount of the porous membrane layer is preferably 0.5 to 50 g / m 2 in terms of dry mass, more preferably 0.5 to 30 g / m 2 , and 1 to 30 g / m 2 . Is more preferable, 1.0 to 15 g / m 2 is particularly preferable, and 3 to 12 g / m 2 is most preferable. It is also possible to adjust the thickness of the battery separator by performing calendar treatment or thermal calendar treatment after drying. The thickness of the battery separator is preferably 10 μm or more, more preferably 12 μm or more, and still more preferably 18 μm or more. The thickness of the battery separator is preferably 30 μm or less. The thin film separator is more preferably 25 μm or less, further preferably 22 μm or less, particularly preferably about 20 μm in thickness (19 to 21 μm), and may be about 20 μm or less.
　電池用セパレータは、裁断されてリチウム二次電池用の電極材料間に挟み込まれて、電解液を注入し、電池を封止して、リチウム二次電池となる。正極を構成する材料は、主に、活物質とカーボンブラック等の導電剤、ポリフッ化ビニリデンやスチレン－ブタジエンゴム（ＳＢＲ）等のバインダーであって、活物質としては、コバルト酸リチウム、ニッケル酸リチウム、マンガン酸リチウム、ニッケルマンガンコバルト酸リチウム（ＮＭＣ）やアルミニウムマンガン酸リチウム（ＡＭＯ）などのリチウムマンガン複合酸化物、鉄リン酸リチウムなどが用いられる。これらは、混合されて集電体であるアルミニウム箔上に塗布されて正極となる。 The battery separator is cut and sandwiched between electrode materials for a lithium secondary battery, an electrolyte is injected, the battery is sealed, and a lithium secondary battery is obtained. The material constituting the positive electrode is mainly an active material, a conductive agent such as carbon black, and a binder such as polyvinylidene fluoride and styrene-butadiene rubber (SBR). The active material includes lithium cobaltate and lithium nickelate. Lithium manganate, nickel manganese lithium cobalt oxide (NMC), lithium manganese manganate such as lithium aluminum manganate (AMO), lithium iron phosphate and the like are used. These are mixed and applied onto an aluminum foil as a current collector to form a positive electrode.
　負極を構成する材料は、主に、活物質と導電剤、結着剤であり、活物質としては、黒鉛、非晶質炭素材料、ケイ素、リチウム、リチウム合金などが用いられる。これらは混合されて、集電体である銅箔上に塗布されて負極となる。 The material constituting the negative electrode is mainly an active material, a conductive agent, and a binder, and graphite, amorphous carbon material, silicon, lithium, lithium alloy, etc. are used as the active material. These are mixed and applied onto a copper foil as a current collector to form a negative electrode.
　リチウム二次電池は、正極、負極間にセパレータを挟み込み、ここに電解液を含浸させて、イオン伝導性を持たせて導通させる。リチウム二次電池では非水系電解液が用いられるが、一般的に、非水系電解液は溶媒と支持電解質で構成させる。溶媒として好ましく用いられるのは、例えばエチレンカーボネイト（ＥＣ）、プロピレンカーボネイト（ＰＣ）、ジエチルカーボネイト（ＤＥＣ）、ジメチルカーボネイト（ＤＭＣ）、エチルメチルカーボネイト（ＥＭＣ）及び添加剤的な働きを有するビニレンカーボネイト、ビニルエチレンカーボネイトなどのカーボネイト系である。ジメトキシエタン（ＤＭＥ）を用いることもできる。支持電解質としては、六フッ化リン酸リチウム（ＬｉＰＦ６）、四フッ化ホウ酸リチウム（ＬｉＢＦ４）のほかに、ＬｉＮ（ＳＯ２ＣＦ３）２などの有機リチウム塩なども用いられる。イオン液体も利用できる。 In a lithium secondary battery, a separator is sandwiched between a positive electrode and a negative electrode, and an electrolytic solution is impregnated therein to provide ionic conductivity and conduct. In the lithium secondary battery, a non-aqueous electrolyte is used. Generally, the non-aqueous electrolyte is composed of a solvent and a supporting electrolyte. As the solvent, for example, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and vinylene carbonate having an additive function, Carbonate such as vinyl ethylene carbonate. Dimethoxyethane (DME) can also be used. As the supporting electrolyte, in addition to lithium hexafluorophosphate (LiPF 6 ) and lithium tetrafluoroborate (LiBF 4 ), an organic lithium salt such as LiN (SO 2 CF 3 ) 2 is also used. Ionic liquids can also be used.
　外装体としては、アルミニウムやステンレススチール等の金属円筒缶や角形缶、アルミニウム箔をポリプロピレン、ポリエチレン、ポリエチレンテレフタレート、ポリブチレンテレフタレート等でラミネート加工したラミネートフィルムを用いたシート型の外装体が利用できる。また、積層化してスタッキングして用いることや、円柱状に回旋して用いることもできる。 As the exterior body, a metal cylindrical can such as aluminum or stainless steel, a rectangular can, a sheet-type exterior body using a laminate film obtained by laminating aluminum foil with polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, or the like can be used. Further, it can be used by stacking and stacking, or it can be used by rotating in a cylindrical shape.
　本発明を実施例によって更に詳細に説明するが、本発明はこれらに何ら限定されるものではない。 The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
＜アルミニウム酸化物系複合体の合成＞
　水酸化アルミニウム（式量７８）４０ｇ（０．５１３ｍｏｌ）と水６０ｇを混合して、ビーズミルで湿式粉砕して平均粒子径０．４μｍの水酸化アルミニウムスラリーを作製した。このスラリーに０．４ｇ（０．０１ｍｏｌ）の水酸化ナトリウム（ＮａＯＨ）を添加して、よく撹拌した後、３００℃で２時間、水熱状態で加熱し、平均粒子径１．２μｍ、厚さ１００ｎｍ、ＡｌＯ０．９（ＯＨ）１．２である板状であるアルミニウム酸化物系複合体１（複合体１）を合成した。 <Synthesis of aluminum oxide composite>
40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.4 μm. To this slurry, 0.4 g (0.01 mol) of sodium hydroxide (NaOH) was added and stirred well, then heated at 300 ° C. for 2 hours in a hydrothermal state, with an average particle size of 1.2 μm, thickness A plate-like aluminum oxide composite 1 (composite 1) having a thickness of 100 nm and AlO 0.9 (OH) 1.2 was synthesized.
　複合体１を、大気中、４３０℃で６時間加熱して、ＡｌＯ１．０５（ＯＨ）０．９であるアルミニウム酸化物系複合体２（複合体２）を得た。 The composite 1 was heated in the atmosphere at 430 ° C. for 6 hours to obtain an aluminum oxide-based composite 2 (composite 2) of AlO 1.05 (OH) 0.9 .
　複合体１を、大気中、４５０℃で６時間加熱して、ＡｌＯ１．２（ＯＨ）０．６であるアルミニウム酸化物系複合体３（複合体３）を得た。 The composite 1 was heated in air at 450 ° C. for 6 hours to obtain an aluminum oxide-based composite 3 (complex 3) of AlO 1.2 (OH) 0.6 .
　複合体１を、大気中、４６０℃で４時間加熱して、ＡｌＯ１．３（ＯＨ）０．４であるアルミニウム酸化物系複合体４（複合体４）を得た。 The complex 1 was heated in the atmosphere at 460 ° C. for 4 hours to obtain an aluminum oxide complex 4 (complex 4) having AlO 1.3 (OH) 0.4 .
　複合体１を、大気中、４７０℃で３時間加熱して、ＡｌＯ１．４（ＯＨ）０．２であるアルミニウム酸化物系複合体５（複合体５）を得た。 The composite 1 was heated in the atmosphere at 470 ° C. for 3 hours to obtain an aluminum oxide-based composite 5 (complex 5) of AlO 1.4 (OH) 0.2 .
　複合体１を、５００℃で６時間加熱して、酸化アルミニウム（Ａｌ２Ｏ３：ＡｌＯｘ（ＯＨ）ｙ、ｘ＝１．５、ｙ＝０）であるアルミニウム酸化物系複合体６（複合体６）を得た。 The composite 1 is heated at 500 ° C. for 6 hours to obtain an aluminum oxide composite 6 (composite) that is aluminum oxide (Al 2 O 3 : AlO x (OH) y, x = 1.5, y = 0). Body 6) was obtained.
　水酸化アルミニウム（式量７８）４０ｇ（０．５１３ｍｏｌ）と水６０ｇを混合して、ビーズミルで湿式粉砕して平均粒子径０．４μｍの水酸化アルミニウムスラリーを作製した。このスラリーに０．４ｇ（０．０１ｍｏｌ）の水酸化ナトリウムを添加して、よく撹拌した後、１７０℃で４時間、水熱状態で加熱し、粒状の平均粒子径０．８μｍ、ＡｌＯ０．４（ＯＨ）２．２であるアルミニウム酸化物系複合体７（複合体７）を合成した。 40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.4 μm. After adding 0.4 g (0.01 mol) of sodium hydroxide to this slurry and stirring well, it was heated in a hydrothermal state at 170 ° C. for 4 hours to obtain a granular average particle size of 0.8 μm, AlO 0. 4 (OH) 2.2 aluminum oxide composite 7 (complex 7) was synthesized.
（実施例１－１）
　下記の材料をホモジナイザー（プライミクス（ＰＲＩＭＩＸ）製、商品名：Ｔ．Ｋ．ＨＯＭＯＤＩＳＰＥＲ　Ｍｏｄｅｌ　２．５、回転数１５００ｒｐｍ）で３時間撹拌して、分散液（１）を作製した。 Example 1-1
The following materials were stirred with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed: 1500 rpm) for 3 hours to prepare dispersion (1).
複合体２　　　　　　　　　　　　　　　　　　　　　　　　６０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ（ＰＯＩＺ）５２０）
　　　　　　　　　　　　　　　　　　　　　　　　　　　　０．５質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　　１００質量部 Complex 2 60 parts by mass of a special carboxylic acid type polymer activator (manufactured by Kao, trade name: POIZ 520)
0.5 parts by mass distilled water 100 parts by mass
　分散液（１）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙（Ｎｉｐｐｏｎ　Ｐａｐｅｒ　Ｉｎｄｕｓｔｒｉｅｓ）製、商品名：ＭＡＣ５００ＬＣ）１００質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を６質量部添加して、塗液（１）を作製した。 Dispersion (1) 100 parts by weight of sodium carboxymethylcellulose aqueous solution (made by Nippon Paper Industries, trade name: MAC500LC) and 100 parts by weight of acrylic latex (JSR, trade name: TRD202A) 6 parts by mass of 40.2% by mass) was added to prepare a coating liquid (1).
　延伸レギュラーポリエチレンテレフタレート（ＰＥＴ）繊維（０．１ｄｔｅｘ、長さ５ｍｍ）３０質量部、延伸レギュラーＰＥＴ繊維（０．３ｄｔｅｘ、長さ５ｍｍ）４０質量部、未延伸ＰＥＴ繊維（０．２ｄｔｅｘ、長さ４ｍｍ）３０質量部の構成で、湿式法により目付量９．５ｇ／ｍ２のウェッブを作製した。この時の乾燥温度は１３０℃であった。次に、１９０℃で熱カレンダー処理を施し、厚さ１５μｍの多孔性支持体（１）を作製した。塗液（１）を多孔性支持体（１）に含浸させた後、１００℃で乾燥させ、塗工量１１ｇ／ｍ２で、厚さ２４μｍのセパレータを得た。 Stretched regular polyethylene terephthalate (PET) fiber (0.1 dtex, length 5 mm) 30 parts by mass, stretched regular PET fiber (0.3 dtex, length 5 mm) 40 parts by mass, unstretched PET fiber (0.2 dtex, length 4 mm) ) A web having a weight per unit area of 9.5 g / m 2 was prepared by a wet method with a composition of 30 parts by mass. The drying temperature at this time was 130 ° C. Next, a thermal calendar process was performed at 190 ° C. to prepare a porous support (1) having a thickness of 15 μm. The porous support (1) was impregnated with the coating liquid (1) and then dried at 100 ° C. to obtain a separator having a coating amount of 11 g / m 2 and a thickness of 24 μm.
（実施例１－２）
　実施例１－１における複合体２の代わりに複合体３を用いて、塗工量１１ｇ／ｍ２で、厚さ２４μｍのセパレータを得た。 Example 1-2
Using composite 3 instead of composite 2 in Example 1-1, a separator having a coating amount of 11 g / m 2 and a thickness of 24 μm was obtained.
（実施例１－３）
　実施例１－１における複合体２の代わりに複合体４を用いて、塗工量１２ｇ／ｍ２で、厚さ２４μｍのセパレータを得た。 (Example 1-3)
Using the composite 4 instead of the composite 2 in Example 1-1, a separator having a coating amount of 12 g / m 2 and a thickness of 24 μm was obtained.
（比較例１－１）
　実施例１－１における複合体２の代わりに複合体１を用いて、塗工量１１ｇ／ｍ２で、厚さ２４μｍの比較セパレータを得た。 (Comparative Example 1-1)
A composite separator 1 was used instead of the composite 2 in Example 1-1 to obtain a comparative separator having a coating amount of 11 g / m 2 and a thickness of 24 μm.
（比較例１－２）
　実施例１－１における複合体２の代わりに複合体５を用いて、塗工量１２ｇ／ｍ２で、厚さ２４μｍの比較セパレータを得た。 (Comparative Example 1-2)
The composite 5 was used in place of the composite 2 in Example 1-1 to obtain a comparative separator having a coating amount of 12 g / m 2 and a thickness of 24 μm.
（比較例１－３）
　実施例１－１における複合体２の代わりに複合体６を用いて、塗工量１２ｇ／ｍ２で、厚さ２４μｍの比較セパレータを得た。 (Comparative Example 1-3)
Using the composite 6 instead of the composite 2 in Example 1-1, a comparative separator having a coating amount of 12 g / m 2 and a thickness of 24 μm was obtained.
（比較例１－４）
　実施例１－１における複合体２の代わりに複合体７を用いて、塗工量１４ｇ／ｍ２で、厚さ２４μｍの比較セパレータを得た。 (Comparative Example 1-4)
Using the composite 7 instead of the composite 2 in Example 1-1, a comparative separator having a coating amount of 14 g / m 2 and a thickness of 24 μm was obtained.
［膜抵抗の測定］
　直径３ｃｍと直径１．５ｃｍの円柱形の銅の間に電解液を含浸させたセパレータを挟み込みこんだ。電解液には、リチウム二次電池用電解液（溶媒：ＥＣ／ＤＥＣ／ＤＭＥ＝１／１／１（体積比）、支持電解質：六フッ化リン酸リチウム（ＬｉＰＦ６）１ｍｏｌ／ｌ）を用いた。両銅を電極として、Ｓｏｌａｔｒｏｎ製、Ｅｌｅｃｔｒｏｃｈｅｍｉｃａｌ　Ｍｅｓｕｒｅｍｅｎｔ　Ｕｎｉｔ　ＳＩ－１２８０Ｂを用いて、電極間の抵抗値を２０ｋＨｚ、１０ｍＶのバイアス電圧で測定した。結果を表１に示した。 [Measurement of membrane resistance]
A separator impregnated with an electrolyte was sandwiched between cylindrical copper having a diameter of 3 cm and a diameter of 1.5 cm. As the electrolytic solution, an electrolytic solution for a lithium secondary battery (solvent: EC / DEC / DME = 1/1/1 (volume ratio), supporting electrolyte: lithium hexafluorophosphate (LiPF 6 ) 1 mol / l) is used. It was. The resistance value between the electrodes was measured at a bias voltage of 20 kHz and 10 mV using Electrochemical Measurement Unit SI-1280B manufactured by Solatron using both coppers as electrodes. The results are shown in Table 1.
［電池特性の評価］
　アルミニウム箔上に、マンガン酸リチウム、アセチレンブラック、ポリフッ化ビニリデンを１００／５／３の質量比で２００ｇ／ｍ２塗工し、溶剤を乾燥して、さらにプレスをかけて正極を作製した。一方、銅箔上に、球状人造黒鉛、アセチレンブラック、ポリフッ化ビニリデンを８５／１５／５の質量比で１００ｇ／ｍ２塗工し、乾燥後プレスをかけて負極を作製した。 [Evaluation of battery characteristics]
On the aluminum foil, 200 g / m 2 of lithium manganate, acetylene black, and polyvinylidene fluoride were applied at a mass ratio of 100/5/3, the solvent was dried, and further pressed to produce a positive electrode. On the other hand, spherical artificial graphite, acetylene black, and polyvinylidene fluoride were coated at a mass ratio of 85/15/5 on a copper foil at a rate of 100 g / m 2 , dried and pressed to prepare a negative electrode.
　両電極間にセパレータを挟み込み、リチウム二次電池用電解液（溶媒：ＥＣ／ＤＥＣ／ＤＭＥ＝１／１／１（体積比）、支持電解質：ＬｉＰＦ６　１ｍｏｌ／ｌ）を滴下し、減圧化でアルミニウム箔ラミネートフィルム中に封止して、リチウム二次電池を作製した。次に、リチウム二次電池を０．２Ｃで４．２Ｖまで充電し、０．２Ｃ（３００分の放電時間）の条件での放電開始から３０分後の電圧から電圧降下値を求め、この電圧降下値から内部抵抗を測定した。さらに、１Ｃでの充放電を１００回繰り返して、１回目の放電容量に対する１００回目の放電容量の割合（容量維持率）を測定した。結果を表１に示した。 A separator is sandwiched between both electrodes, and an electrolyte for a lithium secondary battery (solvent: EC / DEC / DME = 1/1/1 (volume ratio), supporting electrolyte: LiPF 6 1 mol / l) is added dropwise to reduce the pressure. The lithium secondary battery was produced by sealing in an aluminum foil laminate film. Next, the lithium secondary battery was charged to 4.2 V at 0.2 C, and a voltage drop value was obtained from the voltage 30 minutes after the start of discharge under the condition of 0.2 C (discharge time of 300 minutes). The internal resistance was measured from the fall value. Furthermore, the charge / discharge at 1C was repeated 100 times, and the ratio of the 100th discharge capacity to the first discharge capacity (capacity maintenance ratio) was measured. The results are shown in Table 1.
　多孔性支持体と無機微粒子を含有してなる多孔質膜層を有する電池用セパレータにおいて、無機微粒子が、水酸化アルミニウムが残存するアルミニウム酸化物系複合体である場合、即ち無機微粒子がＡｌＯｘ（ＯＨ）ｙ（０．０≦ｘ≦１．０、２ｘ＋ｙ＝３）の場合（比較例１－１及び１－４）、電解液に対する濡れ性が高く、膜抵抗と電池の内部抵抗は低く抑制できたが、電池を繰り返し使用した場合、電池の容量低下が激しかった。比較例１－４では、ガスの発生も確認され、電池が膨張した。一方、無機微粒子が酸化アルミニウムの構造が主となるアルミニウム酸化物系複合体である場合、即ち無機粒子がＡｌＯｘ（ＯＨ）ｙ（１．３＜ｘ、２ｘ＋ｙ＝３）の場合（比較例１－２及び１－３）、電解液に対する濡れ性が低下して、膜抵抗や電池の内部抵抗が上昇するという好ましくない結果を得た。これに対し、無機微粒子がＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）で示されるアルミニウム酸化物系複合体である実施例１－１～１－３の場合、膜抵抗と電池の内部抵抗が低く、かつ繰り返し使用時にも電池の容量低下が抑えられ、耐久性に優れた電池用セパレータが得られた。 In a battery separator having a porous membrane layer containing a porous support and inorganic fine particles, when the inorganic fine particles are an aluminum oxide-based composite in which aluminum hydroxide remains, that is, the inorganic fine particles are AlO x ( In the case of OH) y (0.0 ≦ x ≦ 1.0, 2x + y = 3) (Comparative Examples 1-1 and 1-4), the wettability to the electrolyte is high, and the membrane resistance and the internal resistance of the battery are kept low. However, when the battery was used repeatedly, the capacity of the battery was drastically reduced. In Comparative Example 1-4, gas generation was also confirmed, and the battery expanded. On the other hand, when the inorganic fine particles are an aluminum oxide-based composite mainly composed of aluminum oxide, that is, when the inorganic particles are AlO x (OH) y (1.3 <x, 2x + y = 3) (Comparative Example 1). -2 and 1-3), the wettability with respect to the electrolyte decreased, and the membrane resistance and the internal resistance of the battery were increased. On the other hand, the inorganic fine particle is an aluminum oxide-based composite represented by AlO x (OH) y (1.0 <x ≦ 1.3, 0.4 ≦ y <1.0, 2x + y = 3). In Examples 1-1 to 1-3, the membrane resistance and the internal resistance of the battery were low, and the battery capacity reduction was suppressed even during repeated use, and a battery separator excellent in durability was obtained.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
＜アルミニウム酸化物系複合体の合成＞
　アンモニウムアルミニウム炭酸塩（ＮＨ４ＡｌＣＯ３（ＯＨ）２、式量１３９）７０ｇ（０．５０４ｍｏｌ）と水１００ｇを混合し、ビーズミルで湿式粉砕し、平均粒子径０．５μｍのスラリーを作製した。これを１６０℃で１２時間、水熱状態で加熱し、平均粒子径１．０μｍ、ＡｌＯ１．１（ＯＨ）０．８の粒状のアルミニウム酸化物系複合体８を合成した。アルミニウム酸化物系複合体８のＸ線回折スペクトルを測定し、図１に示した。 <Synthesis of aluminum oxide composite>
70 g (0.504 mol) of ammonium aluminum carbonate (NH 4 AlCO 3 (OH) 2 , formula weight 139) and 100 g of water were mixed and wet-pulverized with a bead mill to prepare a slurry having an average particle size of 0.5 μm. This was heated at 160 ° C. for 12 hours in a hydrothermal state to synthesize a granular aluminum oxide composite 8 having an average particle diameter of 1.0 μm and AlO 1.1 (OH) 0.8 . The X-ray diffraction spectrum of the aluminum oxide composite 8 was measured and shown in FIG.
　水酸化アルミニウム（式量７８）４０ｇ（０．５１３ｍｏｌ）と水６０ｇを混合して、ビーズミルで湿式粉砕して平均粒子径０．３μｍの水酸化アルミニウムスラリーを作製した。このスラリーに０．４ｇ（０．０１ｍｏｌ）の水酸化ナトリウムを添加して、よく撹拌した後、１２０℃で４時間、水熱状態で加熱し、平均粒子径１．０μｍ、ＡｌＯ０．９（ＯＨ）１．２である粒状のアルミニウム酸化物系複合体９（複合体９）を合成した。アルミニウム酸化物系複合体９のＸ線回折スペクトルを測定し、図２に示した。 40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.3 μm. After adding 0.4 g (0.01 mol) of sodium hydroxide to this slurry and stirring well, it was heated in a hydrothermal state at 120 ° C. for 4 hours to obtain an average particle size of 1.0 μm, AlO 0.9 ( OH) A granular aluminum oxide composite 9 (complex 9) of 1.2 was synthesized. The X-ray diffraction spectrum of the aluminum oxide composite 9 was measured and shown in FIG.
　図１及び図２から、アルミニウム酸化物系複合体８では、２θ＝１４．４°のピーク強度（Ｐ１）よりも、２θ＝２８．２°のピーク強度（Ｐ２）が大きく（Ｐ１＜Ｐ２）、アルミニウム酸化物系複合体９では、ピーク強度Ｐ２よりも、ピーク強度Ｐ１が大きい（Ｐ１＞Ｐ２）。 1 and 2, in the aluminum oxide composite 8, the peak intensity (P2) at 2θ = 28.2 ° is larger than the peak intensity (P1) at 2θ = 14.4 ° (P1 <P2). In the aluminum oxide composite 9, the peak intensity P1 is larger than the peak intensity P2 (P1> P2).
（実施例２－１）
　下記の材料をホモジナイザー（プライミクス製、商品名：Ｔ．Ｋ．ＨＯＭＯＤＩＳＰＥＲ　Ｍｏｄｅｌ　２．５、回転数１５００ｒｐｍ）で３時間撹拌して、分散液（２）を作製した。 Example 2-1
The following material was stirred for 3 hours with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed 1500 rpm) to prepare dispersion (2).
複合体８　　　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）０．６質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 8 30 parts by mass Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 0.6 parts by mass Distilled water 150 parts by mass
　分散液（２）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（２）を作製した。 Dispersion (2) 100 parts by mass, 0.6 mass% sodium carboxymethylcellulose aqueous solution (Nippon Paper Industries, trade name: MAC500LC) 50 parts by mass and acrylic latex (JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (2).
　延伸レギュラーＰＥＴ繊維（０．１ｄｔｅｘ、長さ５ｍｍ）３０質量部、延伸レギュラーＰＥＴ繊維（０．３ｄｔｅｘ、長さ５ｍｍ）４０質量部、未延伸ＰＥＴ繊維（０．２ｄｔｅｘ、長さ４ｍｍ）３０質量部の構成で、湿式法により目付量８．０ｇ／ｍ２のウェッブを作製した。この時の乾燥温度は１３０℃であった。次に、１９０℃で熱カレンダー処理を施し、厚さ１５μｍの多孔性支持体（２）を作製した。塗液（２）を多孔性支持体（２）に含浸させた後、１００℃で乾燥させ、塗工量９．０ｇ／ｍ２で、厚さ２２μｍのセパレータを得た。 Stretched regular PET fiber (0.1 dtex, length 5 mm) 30 parts by mass, stretched regular PET fiber (0.3 dtex, length 5 mm) 40 parts by mass, unstretched PET fiber (0.2 dtex, length 4 mm) 30 parts by mass A web having a weight per unit area of 8.0 g / m 2 was prepared by a wet method. The drying temperature at this time was 130 ° C. Next, a thermal calendar process was performed at 190 ° C. to prepare a porous support (2) having a thickness of 15 μm. After impregnating the coating liquid (2) into the porous support (2), it was dried at 100 ° C. to obtain a separator having a coating amount of 9.0 g / m 2 and a thickness of 22 μm.
（比較例２－１）
　下記の材料をホモジナイザー（プライミクス製、商品名：Ｔ．Ｋ．ＨＯＭＯＤＩＳＰＥＲ　Ｍｏｄｅｌ　２．５、回転数１５００ｒｐｍ）で３時間撹拌して、分散液（３）を作製した。 (Comparative Example 2-1)
The following materials were stirred for 3 hours with a homogenizer (manufactured by Primex, trade name: TK HODISPER Model 2.5, rotation speed 1500 rpm) to prepare dispersion (3).
複合体９　　　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）０．６質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 9 30 parts by mass Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 0.6 parts by mass Distilled water 150 parts by mass
　分散液（３）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（３）を作製した。塗液（３）を多孔性支持体（２）に含浸させた後、１００℃で乾燥させて、塗工量９．０ｇ／ｍ２で、厚さ２２μｍのセパレータを得た。 Dispersion (3) 100 parts by mass, 50 parts by mass of 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (3). The porous support (2) was impregnated with the coating liquid (3) and then dried at 100 ° C. to obtain a separator having a coating amount of 9.0 g / m 2 and a thickness of 22 μm.
［電池特性の評価］
　アルミニウム箔上に、マンガン酸リチウム、アセチレンブラック、ポリフッ化ビニリデンを１００／５／３の質量比で２００ｇ／ｍ２塗工し、溶剤を乾燥して、さらにプレスをかけて正極を作製した。一方、銅箔上に、球状人造黒鉛、アセチレンブラック、ポリフッ化ビニリデンを８５／１５／５の質量比で１００ｇ／ｍ２塗工し、乾燥後プレスをかけて負極を作製した。 [Evaluation of battery characteristics]
On the aluminum foil, 200 g / m 2 of lithium manganate, acetylene black, and polyvinylidene fluoride were applied at a mass ratio of 100/5/3, the solvent was dried, and further pressed to produce a positive electrode. On the other hand, spherical artificial graphite, acetylene black, and polyvinylidene fluoride were coated at a mass ratio of 85/15/5 on a copper foil at a rate of 100 g / m 2 , dried and pressed to prepare a negative electrode.
　両電極間にセパレータを挟み込み、リチウム二次電池用電解液（溶媒：ＥＣ／ＤＥＣ／ＤＭＥ＝１／１／１（体積比）、支持電解質：ＬｉＰＦ６　１ｍｏｌ／ｌ）を滴下し、減圧化でアルミニウム箔ラミネートフィルム中に封止して、リチウム二次電池を作製した。次に、リチウム二次電池を０．２Ｃで４．２Ｖまで充電し、０．２Ｃ（３００分の放電時間）の条件での放電開始から３０分後の電圧から電圧降下値を求め、この電圧降下値から内部抵抗を測定した。また、１Ｃにおける放電容量と充電容量を測定し、初回の放電効率（放電容量／充電容量×１００）を測定した。さらに、電池を８０℃で２４時間加熱した後に、１Ｃにおける放電容量と充電容量を測定し、加熱後の放電効率を測定した。結果を表２に示した。 A separator is sandwiched between both electrodes, and an electrolyte for a lithium secondary battery (solvent: EC / DEC / DME = 1/1/1 (volume ratio), supporting electrolyte: LiPF 6 1 mol / l) is added dropwise to reduce the pressure. The lithium secondary battery was produced by sealing in an aluminum foil laminate film. Next, the lithium secondary battery was charged to 4.2 V at 0.2 C, and a voltage drop value was obtained from the voltage 30 minutes after the start of discharge under the condition of 0.2 C (discharge time of 300 minutes). The internal resistance was measured from the fall value. Moreover, the discharge capacity and charge capacity in 1C were measured, and the first discharge efficiency (discharge capacity / charge capacity × 100) was measured. Furthermore, after heating the battery at 80 ° C. for 24 hours, the discharge capacity and charge capacity at 1C were measured, and the discharge efficiency after heating was measured. The results are shown in Table 2.
　実施例２－１と比較例２－１では、どちらも、厚さ２２μｍの薄膜化セパレータが得られている。しかし、Ｐ１よりもＰ２が大きい（Ｐ１＜Ｐ２）アルミニウム酸化物系複合体８を使用した実施例２－１のセパレータを用いた電池は、Ｐ１よりもＰ２が小さい（Ｐ１＞Ｐ２）アルミニウム酸化物系複合体９を使用した比較例２－１のセパレータを用いた電池よりも、内部抵抗が低く、加熱による放電効率の低下も抑制されていた。 In both Example 2-1 and Comparative Example 2-1, a thin film separator having a thickness of 22 μm was obtained. However, the battery using the separator of Example 2-1 using the aluminum oxide-based composite 8 having P2 larger than P1 (P1 <P2) has a P2 smaller than P1 (P1> P2). The internal resistance was lower than that of the battery using the separator of Comparative Example 2-1 using the system composite 9, and the decrease in discharge efficiency due to heating was suppressed.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
＜アルミニウム酸化物系複合体の合成＞
　水酸化アルミニウム（式量７８）４０ｇ（０．５１３ｍｏｌ）と水６０ｇを混合して、ビーズミルで湿式粉砕して平均粒子径０．３μｍの水酸化アルミニウムスラリーを作製した。このスラリーに０．４ｇ（０．０１ｍｏｌ）の水酸化ナトリウムを添加して、よく撹拌した後、１６０℃で２時間、水熱状態で加熱し、平均粒子径１．０μｍ、ＡｌＯ０．９（ＯＨ）１．２のアルミニウム酸化物系複合体１０を合成した。次に、アルミニウム酸化物系複合体１０を４３０℃で６時間加熱して、平均粒子径１．０μｍ、ＡｌＯ１．０５（ＯＨ）０．９である粒状のアルミニウム酸化物系複合体１１（複合体１１）を得た。 <Synthesis of aluminum oxide composite>
40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.3 μm. After adding 0.4 g (0.01 mol) of sodium hydroxide to this slurry and stirring well, it was heated in a hydrothermal state at 160 ° C. for 2 hours to obtain an average particle size of 1.0 μm, AlO 0.9 ( OH) An aluminum oxide composite 10 of 1.2 was synthesized. Next, the aluminum oxide composite 10 is heated at 430 ° C. for 6 hours, and a granular aluminum oxide composite 11 (composite having an average particle diameter of 1.0 μm and AlO 1.05 (OH) 0.9 ) is obtained. Body 11) was obtained.
　アンモニウムアルミニウム炭酸塩（ＮＨ４ＡｌＣＯ３（ＯＨ）２、式量１３９）７０ｇ（０．５０４ｍｏｌ）と水１００ｇを混合し、ビーズミルで湿式粉砕し、平均粒子径０．５μｍのスラリーを作製した。これを２００℃で１２時間、水熱状態で加熱し、平均粒子径２．２μｍ、ＡｌＯ１．１（ＯＨ）０．８である粒状のアルミニウム酸化物系複合体１２（複合体１２）を得た。 70 g (0.504 mol) of ammonium aluminum carbonate (NH 4 AlCO 3 (OH) 2 , formula weight 139) and 100 g of water were mixed and wet-pulverized with a bead mill to prepare a slurry having an average particle size of 0.5 μm. This was heated in a hydrothermal state at 200 ° C. for 12 hours to obtain a granular aluminum oxide composite 12 (composite 12) having an average particle diameter of 2.2 μm and AlO 1.1 (OH) 0.8. It was.
　アルミニウム酸化物系複合体１０を４７０℃で６時間加熱して、平均粒子径１．０μｍのＡｌＯ１．２（ＯＨ）０．６である粒状のアルミニウム酸化物系複合体１３（複合体１３）を得た。 The aluminum oxide-based composite 10 is heated at 470 ° C. for 6 hours to form a granular aluminum oxide-based composite 13 (composite 13) having an average particle diameter of 1.0 μm and AlO 1.2 (OH) 0.6. Got.
　水酸化アルミニウム（式量７８）４０ｇ（０．５１３ｍｏｌ）と水６０ｇを混合して、ビーズミルで湿式粉砕して平均粒子径０．１μｍの水酸化アルミニウムスラリーを作製した。このスラリーに０．４ｇ（０．０１ｍｏｌ）の水酸化ナトリウムを添加して、よく撹拌したのち、１３０℃で４時間、水熱状態で加熱し、平均粒子径０．６μｍ、ＡｌＯ０．９（ＯＨ）１．２である粒状のアルミニウム酸化物系複合体１４（複合体１４）を合成した。 40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.1 μm. After adding 0.4 g (0.01 mol) of sodium hydroxide to this slurry and stirring well, it was heated in a hydrothermal state at 130 ° C. for 4 hours to obtain an average particle size of 0.6 μm, AlO 0.9 ( OH) A granular aluminum oxide composite 14 (composite 14) of 1.2 was synthesized.
　水酸化アルミニウム（式量７８）４０ｇ（０．５１３ｍｏｌ）と水６０ｇを混合して、ビーズミルで湿式粉砕して平均粒子径０．１μｍの水酸化アルミニウムスラリーを作製した。このスラリーに１．２ｇ（０．０３ｍｏｌ）の水酸化ナトリウムを添加して、よく撹拌したのち、１３０℃で４時間、水熱状態で加熱し、平均粒子径０．２μｍ、ＡｌＯ０．９（ＯＨ）１．２である粒状のアルミニウム酸化物系複合体１５（複合体１５）を合成した。 40 g (0.513 mol) of aluminum hydroxide (formula 78) and 60 g of water were mixed and wet pulverized with a bead mill to prepare an aluminum hydroxide slurry having an average particle size of 0.1 μm. After adding 1.2 g (0.03 mol) of sodium hydroxide to this slurry and stirring well, it was heated in a hydrothermal state at 130 ° C. for 4 hours to obtain an average particle size of 0.2 μm, AlO 0.9 ( OH) A granular aluminum oxide composite 15 (composite 15) of 1.2 was synthesized.
（実施例３－１）
　下記の材料をホモジナイザー（プライミクス製、商品名：Ｔ．Ｋ．ＨＯＭＯＤＩＳＰＥＲ　Ｍｏｄｅｌ　２．５、回転数１５００ｒｐｍ）で３時間撹拌して、分散液（４）を作製した。 Example 3-1
The following materials were stirred for 3 hours with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed: 1500 rpm) to prepare dispersion (4).
複合体１１　　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）０．６質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 11 30 parts by mass Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 0.6 parts by mass Distilled water 150 parts by mass
　分散液（４）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（４）を作製した。複合体１１の平均粒子径は、合成時と同じく１．０μｍであった。塗液（４）を多孔性支持体（２）に含浸させた後、１００℃で乾燥させて、塗工量９．０ｇ／ｍ２で、厚さ２２μｍのセパレータを得た。 Dispersion (4) 100 parts by mass, 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, density 40.2) 3% by mass) was added to prepare a coating liquid (4). The average particle diameter of the composite 11 was 1.0 μm as in the synthesis. The porous support (2) was impregnated with the coating liquid (4) and then dried at 100 ° C. to obtain a separator having a coating amount of 9.0 g / m 2 and a thickness of 22 μm.
（実施例３－２）
　塗工量を７．０ｇ／ｍ２にした以外は実施例３－１と同様にして、厚さ２１μｍのセパレータを得た。 (Example 3-2)
A separator having a thickness of 21 μm was obtained in the same manner as in Example 3-1, except that the coating amount was 7.0 g / m 2 .
（実施例３－３）
　塗工量を６．０ｇ／ｍ２にした以外は実施例３－１と同様にして、厚さ２０μｍのセパレータを得た。 (Example 3-3)
A separator having a thickness of 20 μm was obtained in the same manner as in Example 3-1, except that the coating amount was 6.0 g / m 2 .
（実施例３－４）
　下記の材料をビーズミルで２時間撹拌して、分散液（５）を作製した。 (Example 3-4)
The following materials were stirred for 2 hours with a bead mill to prepare dispersion (5).
複合体１２　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）０．６質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 12 30 parts by mass Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 0.6 parts by mass Distilled water 150 parts by mass
　分散液（５）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（５）を作製した。複合体１２の平均粒子径は１．０μｍであった。 Dispersion (5) 100 parts by mass, 50 parts by mass of a 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (5). The average particle size of the composite 12 was 1.0 μm.
　塗液（５）を多孔性支持体（２）に含浸させた後、１００℃で乾燥させて、塗工量７．０ｇ／ｍ２で、厚さ２１μｍのセパレータを得た。 The porous support (2) was impregnated with the coating liquid (5) and then dried at 100 ° C. to obtain a separator having a coating amount of 7.0 g / m 2 and a thickness of 21 μm.
（実施例３－５）
　下記の材料をビーズミルで１２時間撹拌して、分散液（６）を作製した。 (Example 3-5)
The following materials were stirred with a bead mill for 12 hours to prepare dispersion (6).
複合体１２　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）０．６質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 12 30 parts by mass Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 0.6 parts by mass Distilled water 150 parts by mass
　分散液（６）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（６）を作製した。複合体１２の平均粒子径は０．６μｍであった。 Dispersion (6) 50 parts by mass of 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries Co., Ltd., trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (6). The average particle size of the composite 12 was 0.6 μm.
　塗液（６）を多孔性支持体（２）に含浸させた後、１００℃で乾燥させて、塗工量５．８ｇ／ｍ２で、厚さ２０μｍのセパレータを得た。 The porous support (2) was impregnated with the coating liquid (6) and then dried at 100 ° C. to obtain a separator having a coating amount of 5.8 g / m 2 and a thickness of 20 μm.
（実施例３－６）
　下記の材料をビーズミルで２４時間撹拌して、分散液（７）を作製した。 (Example 3-6)
The following materials were stirred with a bead mill for 24 hours to prepare dispersion (7).
複合体１２　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）１．２質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 12 30 parts by weight Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 1.2 parts by weight distilled water 150 parts by weight
　分散液（７）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（７）を作製した。複合体１２の平均粒子径は０．３μｍであった。 Dispersion (7) 50 parts by mass of 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries Co., Ltd., trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3% by mass) was added to prepare a coating liquid (7). The average particle size of the composite 12 was 0.3 μm.
　塗液（７）を多孔性支持体（２）に含浸させた後、１００℃で乾燥させて、塗工量４．５ｇ／ｍ２で、厚さ１９μｍのセパレータを得た。 The porous support (2) was impregnated with the coating liquid (7) and then dried at 100 ° C. to obtain a separator having a coating amount of 4.5 g / m 2 and a thickness of 19 μm.
（実施例３－７）
　下記の材料をビーズミルで２４時間撹拌して、分散液（８）を作製した。 (Example 3-7)
The following materials were stirred with a bead mill for 24 hours to prepare dispersion (8).
複合体１２　　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）３．０質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 12 30 parts by mass Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 3.0 parts by mass distilled water 150 parts by mass
　分散液（８）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（８）を作製した。複合体１２の平均粒子径は０．２μｍであった。 Dispersion (8) 100 parts by mass, 0.6 mass% sodium carboxymethylcellulose aqueous solution (Nippon Paper Industries, trade name: MAC500LC) 50 parts by mass and acrylic latex (JSR, trade name: TRD202A, concentration 40.2) 3 parts by mass) was added to prepare a coating liquid (8). The average particle size of the composite 12 was 0.2 μm.
　塗液（８）を多孔性支持体（２）に含浸させた後、１００℃で乾燥させて、塗工量４．５ｇ／ｍ２で、厚さ１９μｍのセパレータを得た。 The porous support (2) was impregnated with the coating liquid (8) and then dried at 100 ° C. to obtain a separator having a coating amount of 4.5 g / m 2 and a thickness of 19 μm.
（実施例３－８）
　複合体１の代わりに複合体３を用い、塗工量を９．０ｇ／ｍ２にした以外は、実施例３－１と同様にして、厚さ２１μｍのセパレータを得た。 (Example 3-8)
A separator having a thickness of 21 μm was obtained in the same manner as in Example 3-1, except that the composite 3 was used instead of the composite 1 and the coating amount was 9.0 g / m 2 .
（実施例３－９）
　下記の材料をホモジナイザー（プライミクス製、商品名：Ｔ．Ｋ．ＨＯＭＯＤＩＳＰＥＲ　Ｍｏｄｅｌ　２．５、回転数１５００ｒｐｍ）で３時間撹拌して、分散液（９）を作製した。 (Example 3-9)
The following material was stirred for 3 hours with a homogenizer (manufactured by PRIMIX, trade name: TK HODISPER Model 2.5, rotation speed 1500 rpm) to prepare a dispersion (9).
複合体１２　　　　　　　　　　　　　　　　　　　　　　　　３０質量部
特殊カルボン酸型高分子活性剤（花王製、商品名：ポイズ５２０）０．６質量部
蒸留水　　　　　　　　　　　　　　　　　　　　　　　　　１５０質量部 Complex 12 30 parts by mass Special carboxylic acid type polymer activator (trade name: Poise 520, manufactured by Kao) 0.6 parts by mass Distilled water 150 parts by mass
　分散液（９）１００質量部に、濃度０．６質量％カルボキシメチルセルロースナトリウム水溶液（日本製紙製、商品名：ＭＡＣ５００ＬＣ）５０質量部とアクリル系ラテックス（ＪＳＲ製、商品名：ＴＲＤ２０２Ａ、濃度４０．２質量％）を３質量部添加して、塗液（１）を作製した。複合体２の平均粒子径は、合成時と同じく２．２μｍであった。 Dispersion (9) in 100 parts by mass, 50 parts by mass of a 0.6 mass% sodium carboxymethylcellulose aqueous solution (manufactured by Nippon Paper Industries, trade name: MAC500LC) and acrylic latex (manufactured by JSR, trade name: TRD202A, concentration 40.2) 3 parts by mass) was added to prepare a coating liquid (1). The average particle diameter of the composite 2 was 2.2 μm as in the synthesis.
　塗液（９）を多孔性支持体（２）に含浸させて、１００℃で乾燥させて、塗工量１５．０ｇ／ｍ２で、厚さ２７μｍのセパレータを得た。 The porous support (2) was impregnated with the coating liquid (9) and dried at 100 ° C. to obtain a separator having a coating amount of 15.0 g / m 2 and a thickness of 27 μm.
（実施例３－１０）
　塗工量を９．０ｇ／ｍ２にした以外は実施例３－９と同様にして、厚さ２４μｍのセパレータを得た。 (Example 3-10)
A separator having a thickness of 24 μm was obtained in the same manner as in Example 3-9 except that the coating amount was 9.0 g / m 2 .
（実施例３－１１）
　塗工量を７．０ｇ／ｍ２にした以外は実施例３－９と同様にして、厚さ２２μｍのセパレータを得た。 (Example 3-11)
A separator having a thickness of 22 μm was obtained in the same manner as in Example 3-9 except that the coating amount was 7.0 g / m 2 .
（比較例３－１）
　複合体１２の代わりに複合体１４を用い、塗工量を６．０ｇ／ｍ２にした以外は、実施例３－９と同様にして、厚さ２０μｍのセパレータを得た。 (Comparative Example 3-1)
A separator having a thickness of 20 μm was obtained in the same manner as in Example 3-9, except that the composite 14 was used instead of the composite 12 and the coating amount was 6.0 g / m 2 .
（比較例３－２） (Comparative Example 3-2)
　複合体２の代わりに複合体１５を用い、塗工量を４．５ｇ／ｍ２にした以外は、実施例３－９と同様にして、厚さ１９μｍのセパレータを得た。 A separator having a thickness of 19 μm was obtained in the same manner as in Example 3-9, except that the composite 15 was used in place of the composite 2 and the coating amount was 4.5 g / m 2 .
［電池特性の評価］
　アルミニウム箔上に、マンガン酸リチウム、アセチレンブラック、ポリフッ化ビニリデンを１００／５／３の質量比で２００ｇ／ｍ２塗工し、溶剤を乾燥して、さらにプレスをかけて正極を作製した。一方、銅箔上に、球状人造黒鉛、アセチレンブラック、ポリフッ化ビニリデンを８５／１５／５の質量比で１００ｇ／ｍ２塗工し、乾燥後プレスをかけて負極を作製した。 [Evaluation of battery characteristics]
On the aluminum foil, 200 g / m 2 of lithium manganate, acetylene black, and polyvinylidene fluoride were applied at a mass ratio of 100/5/3, the solvent was dried, and further pressed to produce a positive electrode. On the other hand, spherical artificial graphite, acetylene black, and polyvinylidene fluoride were coated at a mass ratio of 85/15/5 on a copper foil at a rate of 100 g / m 2 , dried and pressed to prepare a negative electrode.
　両電極間にセパレータを挟み込み、リチウム二次電池用電解液（溶媒：ＥＣ／ＤＥＣ／ＤＭＥ＝１／１／１（体積比）、支持電解質：ＬｉＰＦ６　１ｍｏｌ／ｌ）を滴下し、減圧化でアルミニウム箔ラミネートフィルム中に封止して、リチウム二次電池を作製した。次に、リチウム二次電池を０．２Ｃで４．２Ｖまで充電し、０．２Ｃ（３００分の放電時間）の条件での放電開始から３０分後の電圧から電圧降下値を求め、この電圧降下値から内部抵抗を測定した。また、１Ｃにおける放電容量と充電容量を測定し、初回の放電効率（放電容量／充電容量×１００）を測定した。さらに、電池を８０℃で２４時間加熱した後に、１Ｃにおける放電容量と充電容量を測定し、加熱後の放電効率を測定した。結果を表３に示した。また、各セパレータの平均細孔径を測定して、表３に示した。 A separator is sandwiched between both electrodes, and an electrolyte for a lithium secondary battery (solvent: EC / DEC / DME = 1/1/1 (volume ratio), supporting electrolyte: LiPF 6 1 mol / l) is added dropwise to reduce the pressure. The lithium secondary battery was produced by sealing in an aluminum foil laminate film. Next, the lithium secondary battery was charged to 4.2 V at 0.2 C, and a voltage drop value was obtained from the voltage 30 minutes after the start of discharge under the condition of 0.2 C (discharge time of 300 minutes). The internal resistance was measured from the fall value. Moreover, the discharge capacity and charge capacity in 1C were measured, and the first discharge efficiency (discharge capacity / charge capacity × 100) was measured. Furthermore, after heating the battery at 80 ° C. for 24 hours, the discharge capacity and charge capacity at 1C were measured, and the discharge efficiency after heating was measured. The results are shown in Table 3. The average pore diameter of each separator was measured and shown in Table 3.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　実施例３－１～３－８のセパレータは、多孔性支持体と無機微粒子を含有してなる多孔質膜層を有し、無機微粒子が、水熱合成によって得られたＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）で示されるアルミニウム酸化物系複合体であり、その平均粒子径が０．２～１．０μｍであるセパレータである。いずれのセパレータも、厚さが２２μｍ以下であり、薄膜化に対応することができている。また、無機微粒子の過剰な水酸基が少ないため、無機微粒子の電解液への耐久性が高く、初回放電効率と加熱後放電効率を比較すると、ほとんど同じであった。 The separators of Examples 3-1 to 3-8 have a porous membrane layer containing a porous support and inorganic fine particles, and the inorganic fine particles were obtained from AlO x (OH) y obtained by hydrothermal synthesis. (1.0 <x ≦ 1.3, 0.4 ≦ y <1.0, 2x + y = 3), and an average particle diameter of 0.2 to 1.0 μm. It is a certain separator. All the separators have a thickness of 22 μm or less, and can cope with thinning. In addition, since the inorganic fine particles have few excessive hydroxyl groups, the durability of the inorganic fine particles to the electrolytic solution is high, and the initial discharge efficiency and the discharge efficiency after heating are almost the same.
　実施例３－９～３－１１では、無機微粒子が２．２μｍの水熱合成によって得られたＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）で示されるアルミニウム酸化物系複合体である。平均粒子径が１．０μｍを超えているため、塗工量が７．０ｇ／ｍ２及び９．０ｇ／ｍ２であり、セパレータの厚さが２４μｍと２２μｍである実施例３－１０及び３－１１では、平均細孔径が増大して、放電効率が低くなった。この無機微粒子では、電池を安定に動作させるためには、実施例３－９のように、塗工量１５ｇ／ｍ２が必要であり、その場合、セパレータの厚さは２７μｍで、薄膜化に対応することが難しかった。 In Examples 3-9 to 3-11, AlO x (OH) y (1.0 <x ≦ 1.3, 0.4 ≦ y <1. 0, 2x + y = 3). Examples 3-10 and 3 in which the average particle diameter exceeds 1.0 μm, the coating amounts are 7.0 g / m 2 and 9.0 g / m 2 , and the separator thickness is 24 μm and 22 μm. At -11, the average pore diameter increased and the discharge efficiency decreased. In order to operate the battery stably with this inorganic fine particle, a coating amount of 15 g / m 2 is required as in Example 3-9. In that case, the thickness of the separator is 27 μm, and it is necessary to reduce the thickness of the battery. It was difficult to respond.
　比較例３－１では、無機微粒子の平均粒子径が０．６μｍであり、比較例３－２では、無機微粒子の平均粒子径が０．２μｍである。そのため、どちらも厚さ２０μｍ以下のセパレータが得られていて、初回放電効率は９０％であり、問題が無かった。しかし、ｘが１．０以下であり（ｘ≦１．０）、ｙが１．０以上であるため（ｙ≧１．０）、無機微粒子の過剰な水酸基によって、加熱によって電池特性が著しく低下し、加熱後放電効率は５５％以下にまで低下した。 In Comparative Example 3-1, the average particle size of the inorganic fine particles is 0.6 μm, and in Comparative Example 3-2, the average particle size of the inorganic fine particles is 0.2 μm. Therefore, in both cases, a separator having a thickness of 20 μm or less was obtained, and the initial discharge efficiency was 90%, and there was no problem. However, since x is 1.0 or less (x ≦ 1.0) and y is 1.0 or more (y ≧ 1.0), the battery characteristics are significantly deteriorated by heating due to excessive hydroxyl groups of the inorganic fine particles. However, the discharge efficiency after heating decreased to 55% or less.
　実施例３－１～３－４では、平均粒子径１．０μｍで、水熱合成によって得られたＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）で示されるアルミニウム酸化物系複合体を用いている。塗工量が６．０ｇ／ｍ２である実施例３－３では、実施例３－１、３－２及び３－４と比較して、放電効率が低下した。よって、電池をより安定に動作させるためには、塗工量は７．０ｇ／ｍ２以上であることが好ましいことがわかる。なお、実施例３－１～３－４では、セパレータの厚さが２０～２２μｍであり、塗工量が６．０ｇ／ｍ２である実施例３－３では、２０μｍである。実施例３－５では、平均粒子径０．６μｍのアルミニウム酸化物系複合体を用いているが、塗工量が５．８ｇ／ｍ２と少ないにも係わらず、放電効率も高く、内部抵抗も低く、電池を安定に動作させることができ、厚さが２０μｍという薄膜化セパレータの製造が可能であった。 In Examples 3-1 to 3-4, AlO x (OH) y (1.0 <x ≦ 1.3, 0.4 ≦ y <1) obtained by hydrothermal synthesis with an average particle size of 1.0 μm. 0.0, 2x + y = 3) is used. In Example 3-3 in which the coating amount was 6.0 g / m 2 , the discharge efficiency was lowered as compared with Examples 3-1, 3-2 and 3-4. Therefore, it can be seen that the coating amount is preferably 7.0 g / m 2 or more in order to operate the battery more stably. In Examples 3-1 to 3-4, the thickness of the separator is 20 to 22 μm, and in Example 3-3 in which the coating amount is 6.0 g / m 2, it is 20 μm. In Example 3-5, an aluminum oxide composite having an average particle size of 0.6 μm was used, but the discharge efficiency was high and the internal resistance was small despite the coating amount being as low as 5.8 g / m 2. Therefore, the battery can be operated stably, and a thin film separator having a thickness of 20 μm can be manufactured.
　実施例３－６及び３－７では、無機微粒子の平均粒子径が更に小さく、０．３μｍ及び０．２μｍである。その結果、塗工量が４．５ｇ／ｍ２と少なく、セパレータの厚さは１９μｍであり、更に薄くすることができた。無機微粒子の平均粒子径が小さくなったため、無機微粒子の充填率が上がり、電池の内部抵抗が実施例３－１～３－５と比較すると、若干増大した。しかし、初回放電効率は９０％と高く、加熱後放電効率も高かった。 In Examples 3-6 and 3-7, the average particle diameter of the inorganic fine particles is further smaller, being 0.3 μm and 0.2 μm. As a result, the coating amount was as small as 4.5 g / m 2 and the thickness of the separator was 19 μm, which could be further reduced. Since the average particle size of the inorganic fine particles was reduced, the filling rate of the inorganic fine particles was increased, and the internal resistance of the battery was slightly increased as compared with Examples 3-1 to 3-5. However, the initial discharge efficiency was as high as 90%, and the discharge efficiency after heating was also high.
　実施例３－８で使用したアルミニウム酸化物系複合体１３は、ｘ＝１．２、ｙ＝０．６であり、実施例３－１で使用したアルミニウム酸化物系複合体１１は、ｘ＝１．０５、ｙ＝０．９である。アルミニウム酸化物系複合体の水酸基の量が多い実施例３－１の方が、内部抵抗は低く優れていて、該水酸基の量が少ない実施例３－８の方が、放電効率が高く優れていた。 The aluminum oxide composite 13 used in Example 3-8 is x = 1.2 and y = 0.6, and the aluminum oxide composite 11 used in Example 3-1 is x = 1.2. 1.05, y = 0.9. Example 3-1 in which the amount of hydroxyl groups in the aluminum oxide-based composite is large is superior in lower internal resistance, and Example 3-8 in which the amount of hydroxyl groups is small is superior in discharge efficiency. It was.
　これらの結果より、過剰な水酸基が少なく、平均粒子径が０．２～１．０μｍである無機微粒子によって、薄膜化セパレータを製造することができ、特に厚さ２０μｍ程度又はそれ以下のセパレータを製造することもでき、かつ、電解液への耐久性が高く、電池を安定に動作させることができ、電池の内部抵抗を低くすることもできることが示された。 From these results, it is possible to produce a thin film separator using inorganic fine particles with a small excess of hydroxyl groups and an average particle size of 0.2 to 1.0 μm, and particularly a separator having a thickness of about 20 μm or less. In addition, it was shown that the battery has high durability against the electrolyte, can operate the battery stably, and can reduce the internal resistance of the battery.
　本発明の電池用セパレータは、リチウム二次電池用セパレータのほか、キャパシタ用セパレータとして利用できる。 The battery separator of the present invention can be used as a capacitor separator in addition to a lithium secondary battery separator.

Claims (3)

  1. 　多孔性支持体と無機微粒子を含有してなる多孔質膜層を有する電池用セパレータにおいて、該無機微粒子が、水熱合成によって得られたＡｌＯｘ（ＯＨ）ｙ（１．０＜ｘ≦１．３、０．４≦ｙ＜１．０、２ｘ＋ｙ＝３）で示されるアルミニウム酸化物系複合体であることを特徴とする電池用セパレータ。 In a battery separator having a porous membrane layer comprising a porous support and inorganic fine particles, the inorganic fine particles are obtained by hydrothermal synthesis of AlO x (OH) y (1.0 <x ≦ 1. 3, 0.4 ≦ y <1.0, 2x + y = 3) A battery separator characterized by being an aluminum oxide composite.
  2. 　該無機微粒子のＸ線回折による２θ＝１４．４°のピーク強度（Ｐ１）よりも、２θ＝２８．２°のピーク強度（Ｐ２）が大きい（Ｐ１＜Ｐ２）、請求項１記載の電池用セパレータ。 The battery according to claim 1, wherein the peak intensity (P2) of 2θ = 28.2 ° is larger than the peak intensity (P1) of 2θ = 14.4 ° by X-ray diffraction of the inorganic fine particles (P1 <P2). Separator.
  3. 　該無機微粒子の平均粒子径が０．２～１．０μｍである、請求項１又は２記載の電池用セパレータ。 The battery separator according to claim 1 or 2, wherein the inorganic fine particles have an average particle size of 0.2 to 1.0 µm.
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