WO2012023197A1 - Batterie secondaire lithium-ion et séparateur utilisé dans ladite batterie - Google Patents

Batterie secondaire lithium-ion et séparateur utilisé dans ladite batterie Download PDF

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Publication number
WO2012023197A1
WO2012023197A1 PCT/JP2010/064004 JP2010064004W WO2012023197A1 WO 2012023197 A1 WO2012023197 A1 WO 2012023197A1 JP 2010064004 W JP2010064004 W JP 2010064004W WO 2012023197 A1 WO2012023197 A1 WO 2012023197A1
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Prior art keywords
heat
separator
resin layer
resistant layer
layer
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PCT/JP2010/064004
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English (en)
Japanese (ja)
Inventor
上木　智善
島村　治成
福本　友祐
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トヨタ自動車株式会社
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Priority to PCT/JP2010/064004 priority Critical patent/WO2012023197A1/fr
Publication of WO2012023197A1 publication Critical patent/WO2012023197A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a lithium ion secondary battery and a separator for the battery.
  • a porous separator is disposed between the positive electrode and the negative electrode.
  • the separator plays a role of preventing a short circuit due to contact between the positive electrode and the negative electrode.
  • the separator also plays a role of forming an ion conduction path (conduction path) between both electrodes by impregnating the electrolyte in the pores of the separator.
  • a separator having a porous resin layer made of polyethylene (PE), polypropylene (PP) or the like has been used as a separator for a lithium ion secondary battery.
  • Such a separator has a so-called shutdown function and also serves to prevent overheating of the battery. That is, the separator having such a resin layer blocks the ion conduction between both electrodes because the resin melts and closes the pores when the battery temperature rises excessively due to an internal short circuit or the like. . Therefore, charging / discharging of the battery is forcibly stopped, and further temperature rise is prevented.
  • Patent Documents 1 to 5 disclose such separators.
  • lithium ion secondary batteries In recent years, the application range of lithium ion secondary batteries has been rapidly expanding, and its use is being examined in vehicles and other fields. In the lithium ion secondary battery provided with the separator as described above, more excellent battery characteristics and overheat prevention properties are required.
  • an object of the present invention is to provide a lithium ion secondary battery having excellent battery characteristics and overheating prevention properties, and a lithium ion secondary battery separator capable of constructing the battery. Another object is to provide a method for producing such a separator.
  • the inventor applied a heat-resistant layer forming composition containing an inorganic filler and a binder to the surface of a porous resin layer to form a porous heat-resistant layer.
  • the present invention was completed by finding that the increase in electrical resistance accompanying the formation of the layer can be effectively suppressed.
  • a lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte.
  • the separator has a porous resin layer and a porous heat-resistant layer laminated on at least one surface of the resin layer.
  • the heat-resistant layer includes a filler made of an inorganic material (for example, an inorganic oxide, an inorganic hydroxide, etc.) and a binder.
  • the porosity of the resin layer before the heat resistant layer is laminated is 45% to 65%.
  • the porosity of the heat-resistant layer in the separator is 45% to 65%.
  • the total volume of pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m in the unit mass of the resin layer before the heat resistant layer is laminated is the pore volume A, and the separator (that is, the heat resistant layer is laminated).
  • B / A ⁇ 100 The pore volume ratio is 60% to 90%.
  • a heat-resistant layer containing an inorganic filler and a binder is laminated on the resin layer.
  • the heat-resistant layer and the resin layer are firmly bonded by a binder. Even if the temperature of the separator rises, the heat-resistant layer hardly undergoes thermal shrinkage. Therefore, even if the temperature of the separator rises, the heat-resistant layer regulates the heat shrinkage of the resin layer, and therefore the resin layer is unlikely to cause heat shrinkage. Therefore, the short circuit resulting from the thermal contraction of the resin layer can be better prevented.
  • the heat-resistant layer When forming the heat-resistant layer on the surface of the resin layer, part of the binder enters into the pores of the resin layer, and the amount of pores in the resin layer decreases.
  • the heat-resistant layer When the heat-resistant layer is formed thicker, the amount of binder entering the pores of the resin layer increases, and when the heat-resistant layer is formed thinner, the amount of binder entering the pores of the resin layer tends to decrease. It is in. Therefore, when the heat-resistant layer is formed larger, the pore volume ratio tends to be smaller, and when the heat-resistant layer is formed smaller, the pore volume ratio tends to be larger.
  • the binder can enter into the pores of the resin layer and reduce the amount of pores in the resin layer, but the binder also has the property of smoothing the surface of the pores.
  • the surface of the pore becomes smooth, movement of lithium ions through the pore becomes easy. Therefore, if the heat-resistant layer is not too large, the effect of smoothing the surface of the pores is superior to the effect that some of the pores of the resin layer are blocked by the binder, and the movement of lithium ions becomes easy. Ionic conductivity is improved. Therefore, an increase in the electrical resistance of the separator accompanying the lamination of the heat resistant layer is suppressed. Further, since the electrolytic solution is held in the pores of the heat-resistant layer, the increase in the electrical resistance of the separator can be suppressed by this.
  • the pore amount ratio regarding pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m is 60% or more, and the heat-resistant layer is not too large. Therefore, an increase in the electrical resistance of the separator accompanying the lamination of the heat resistant layer is suppressed, and excellent battery characteristics can be obtained.
  • the heat-resistant layer is too small, it is difficult to effectively suppress the heat shrinkage of the resin layer.
  • the pore volume ratio for pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m is 90% or less, and the heat-resistant layer is not too small. Therefore, the heat shrinkage of the resin layer can be effectively suppressed.
  • the separator it is possible to construct a lithium ion secondary battery having excellent battery characteristics and overheating prevention properties.
  • the resin layer is made of a polyolefin resin.
  • the resin layer is made of a uniaxially or biaxially stretched porous resin sheet. According to such a resin layer, the effect of smoothing the surface of the pores by the binder is preferably obtained, and an increase in electrical resistance accompanying the lamination of the heat-resistant layer can be suitably suppressed.
  • the filler is made of at least one material selected from the group consisting of alumina, boehmite, magnesia, and magnesium hydroxide.
  • the binder is made of at least one material selected from the group consisting of an acrylic binder, a styrene butadiene rubber, and a polyolefin binder. According to such a binder, the effect of smoothing the surface of the pores of the resin layer is preferably obtained, and an increase in electrical resistance accompanying the lamination of the heat-resistant layer can be suitably suppressed.
  • a method for producing a separator for a lithium ion secondary battery includes a first step of preparing a porous resin sheet having a porosity of 45% to 65%. Moreover, the said manufacturing method adds and knead
  • an inorganic material for example, inorganic oxide, inorganic hydroxide, etc.
  • the porosity of the heat-resistant layer is 45% to 65%, and the pore diameter of 0.05 ⁇ m to 2 ⁇ m included in the unit mass of the resin sheet before the heat-resistant layer is laminated.
  • the pore volume ratio defined by 100 is 60% to 90%.
  • the second step is a step of preparing the composition for forming the heat-resistant layer so that the solid content thereof is 30% by mass to 50% by mass. is there.
  • the second step is a step of preparing the composition for forming the heat-resistant layer so that the viscosity thereof is 30 mPa ⁇ s to 120 mPa ⁇ s.
  • a lithium ion secondary battery including any separator disclosed herein or a separator produced by any production method disclosed herein.
  • the technology disclosed herein can be preferably applied to a lithium ion secondary battery mounted on a vehicle (for example, for a vehicle driving power source) and a separator for the battery.
  • a vehicle including such a lithium ion secondary battery (typically provided as a vehicle driving power source) is provided.
  • FIG. 1 is a schematic cross-sectional view showing the structure of a lithium ion secondary battery according to an embodiment.
  • FIG. 2 is a schematic cross-sectional view of a separator according to an embodiment.
  • FIG. 3 is a schematic cross-sectional view of a separator according to another embodiment.
  • FIG. 4A is a schematic cross-sectional view conceptually showing the surface state of the pores in the resin layer before forming the heat-resistant layer.
  • FIG. 4B is a schematic cross-sectional view conceptually showing the surface state of the pores in the resin layer after the heat-resistant layer is formed.
  • FIG. 5 is a schematic side view showing a vehicle (automobile) provided with a lithium ion secondary battery according to an embodiment.
  • FIG. 1 shows a lithium ion secondary battery 10 according to an embodiment of the present invention.
  • the lithium ion secondary battery 10 has a configuration in which the electrode body 11 is accommodated in the battery case 15 together with the non-aqueous electrolyte 20. At least a part of the nonaqueous electrolytic solution 20 is impregnated in the electrode body 11.
  • the electrode body 11 includes a positive electrode 12, a negative electrode 14, and a separator 13.
  • the positive electrode 12 has a long sheet-like positive electrode current collector 122 and a positive electrode mixture layer 124 containing a positive electrode active material and provided on the positive electrode current collector 122.
  • the negative electrode 14 includes a long sheet-like negative electrode current collector 142 and a negative electrode mixture layer 144 that includes a negative electrode active material and is provided on the negative electrode current collector 142.
  • the separator 13 is formed in a long sheet shape.
  • the positive electrode 12 and the negative electrode 14 are wound in a cylindrical shape together with the two separators 13 so that the separator 13 is interposed therebetween. Thereby, the electrode body 11 is formed.
  • the battery case 15 includes a bottomed cylindrical case body 152 and a lid 154 that closes the opening.
  • the lid 154 and the case main body 152 are both made of metal and insulated from each other.
  • the lid 154 is electrically connected to the positive electrode current collector 122, and the case main body 152 is electrically connected to the negative electrode current collector 142.
  • the lid 154 also serves as a positive electrode terminal, and the case main body 152 serves as a negative electrode terminal.
  • a portion where the current collector 122 is exposed without being provided with the positive electrode mixture layer 124 is provided on one edge along the longitudinal direction of the positive electrode current collector 122 (the upper edge in FIG. 1).
  • a lid 154 is electrically connected to the exposed portion.
  • the case main body 152 is electrically connected to the exposed portion.
  • the non-aqueous electrolyte solution contains a lithium salt as a supporting salt in an organic solvent (non-aqueous solvent).
  • a lithium salt for example, a known lithium salt conventionally used as a supporting salt for a non-aqueous electrolyte solution of a lithium ion secondary battery can be appropriately selected and used.
  • lithium salts include LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , Li (CF 3 SO 2 ) 2 N, LiCF 3 SO 3 and the like.
  • These supporting salts can be used alone or in combination of two or more.
  • a particularly preferred example is LiPF 6 .
  • the non-aqueous electrolyte is preferably prepared, for example, so that the concentration of the supporting salt is within a range of 0.7 to 1.6 mol / L.
  • non-aqueous solvent an organic solvent used in a general lithium ion secondary battery can be appropriately selected and used.
  • Particularly preferred non-aqueous solvents include carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and propylene carbonate (PC). These organic solvents can be used alone or in combination of two or more.
  • a conductive member made of a highly conductive metal is preferably used.
  • aluminum or an alloy containing aluminum as a main component can be used.
  • the shape of the positive electrode current collector 122 may vary depending on the shape of the lithium ion secondary battery, and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. .
  • a sheet-like aluminum positive electrode current collector 122 is used.
  • an aluminum sheet having a thickness of about 10 ⁇ m to 30 ⁇ m can be suitably used.
  • the positive electrode mixture layer 124 may contain, in addition to the positive electrode active material, a conductive material, a binder (binder), and the like as necessary.
  • a conductive material a carbon material such as carbon black (for example, acetylene black) or graphite powder can be preferably used as in the case of a conductive material in an electrode of a general lithium ion secondary battery.
  • a binder polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), or the like can be used.
  • the amount of the conductive material used relative to 100 parts by mass of the positive electrode active material can be, for example, 1 to 20 parts by mass (preferably 5 to 15 parts by mass). Further, the amount of the binder used relative to 100 parts by mass of the positive electrode active material can be, for example, 0.5 to 10 parts by mass.
  • the positive electrode mixture layer 124 can be produced, for example, as follows. First, a composition (typically a paste or slurry-like composition) in which a positive electrode active material and a conductive material are dispersed in a liquid medium containing an appropriate solvent and a binder is prepared. Next, the composition is applied to the positive electrode current collector 122 and dried, and then pressed as desired. Thereby, the positive electrode mixture layer 124 can be obtained.
  • a solvent all of water, an organic solvent, and these mixed solvents can be used.
  • the positive electrode active material a material capable of inserting and extracting lithium is used, and one or more of materials conventionally used in lithium ion secondary batteries (for example, a layered oxide or a spinel oxide) Can be used without any particular limitation.
  • materials conventionally used in lithium ion secondary batteries for example, a layered oxide or a spinel oxide
  • lithium-containing composite oxides such as lithium nickel composite oxides, lithium cobalt composite oxides, lithium manganese composite oxides, and lithium magnesium composite oxides.
  • the lithium nickel-based composite oxide is an oxide having lithium (Li) and nickel (Ni) as constituent metal elements, and at least one other metal element (that is, Li and nickel) in addition to lithium and nickel.
  • Examples of the metal element other than Li and Ni include, for example, cobalt (Co), aluminum (Al), manganese (Mn), chromium (Cr), iron (Fe), vanadium (V), magnesium (Mg), and titanium (Ti ), Zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W), copper (Cu), zinc (Zn), gallium (Ga), indium (In), tin (Sn), lanthanum (La) ), And one or more metal elements selected from the group consisting of cerium (Ce). The same meaning is applied to lithium cobalt complex oxides, lithium manganese complex oxides, and lithium magnesium complex oxides.
  • an olivine type lithium phosphate represented by a general formula LiMPO 4 (M is at least one element of Co, Ni, Mn, Fe; for example, LiFeO 4 , LiMnPO 4 ) is used as the positive electrode active material. Also good.
  • the amount of the positive electrode active material contained in the positive electrode mixture can be appropriately selected and can be, for example, 80% by mass to 95% by mass.
  • a conductive member made of a highly conductive metal is preferably used.
  • copper or an alloy containing copper as a main component can be used.
  • the shape of the negative electrode current collector 142 may vary depending on the shape of the lithium ion secondary battery, and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. .
  • a sheet-like copper negative electrode current collector 142 is used.
  • a copper sheet having a thickness of about 5 ⁇ m to 30 ⁇ m can be suitably used.
  • the negative electrode mixture layer 144 may contain a conductive material, a binder, and the like similar to those of the positive electrode mixture layer 124 as necessary, in addition to the negative electrode active material.
  • the amount of the binder used relative to 100 parts by mass of the negative electrode active material can be, for example, 0.5 to 10 parts by mass.
  • the negative electrode mixture layer 144 is a composition in which the negative electrode active material is dispersed in a liquid medium containing an appropriate solvent and a binder, and the composition is used as the negative electrode current collector 142. It can be preferably prepared by applying to lysate, drying, and pressing as desired.
  • the negative electrode active material one type or two or more types of materials conventionally used in lithium ion secondary batteries can be used without particular limitation.
  • a carbon particle is mentioned as a suitable negative electrode active material.
  • a particulate carbon material (carbon particles) containing a graphite structure (layered structure) at least partially is preferably used. Any carbon material of a so-called graphitic material (graphite), non-graphitizable carbon material (hard carbon), easily graphitized carbon material (soft carbon), or a combination of these materials is preferably used. Can be done.
  • the amount of the negative electrode active material contained in the negative electrode mixture is not particularly limited, but is preferably about 90% by mass to 99% by mass, more preferably about 95% by mass to 99% by mass.
  • FIG. 2 shows a separator 13 according to one embodiment
  • FIG. 3 shows a separator 13 according to another embodiment.
  • the separator 13 includes a porous resin layer 60 and a heat-resistant layer 70 laminated on one surface of the resin layer 60. It is possible to provide the heat-resistant layer 70 on both surfaces of the resin layer 60.
  • the separator 13 is formed in a long sheet shape. However, since the shape of the separator 13 may vary depending on the shape of the lithium ion secondary battery, it is not particularly limited to a sheet shape.
  • the material of the resin layer 60 for example, a polyolefin resin such as PE or PP can be suitably used.
  • the structure of the resin layer 60 may be a single layer structure or a multilayer structure.
  • FIG. 2 shows an example of the separator 13 having the resin layer 60 having a three-layer structure.
  • the resin layer 60 includes a PP layer 61, a PE layer 62 laminated on the PP layer 61, and a PP layer 63 laminated on the PE layer 62.
  • the number of layers of the resin layer 60 having a multilayer structure is not limited to 3, and may be 2 or 4 or more.
  • FIG. 3 shows an example of the separator 13 having the resin layer 60 having a single layer structure.
  • the resin layer 60 is constituted by a PE layer 62.
  • the PE layer 62 is preferably composed of PE having a melting point of about 120 ° C. to 140 ° C. (typically 125 ° C. to 135 ° C.). The melting point is sufficiently lower than the temperature at which the battery 10 is thermally runaway (for example, about 1000 ° C. or higher).
  • Examples of such PE include polyesters generally referred to as high-density polyethylene or linear (linear) low-density polyethylene.
  • the PP layers 61 and 63 are preferably composed of PP each having a melting point of about 150 ° C. to 170 ° C. (typically 155 ° C. to 165 ° C.). The melting point is also sufficiently lower than the temperature at which the battery 10 is thermally runaway. Examples of such polypropylene include isotactic polypropylene and syndiotactic polypropylene.
  • the melting points of both PP layers 61 and 63 may be the same or different. Typically, the melting points of both PP layers 61 and 63 are substantially equal.
  • a uniaxially or biaxially stretched porous resin film can be suitably used.
  • a porous resin film uniaxially stretched in the longitudinal direction is particularly preferable because it has an appropriate strength and has little heat shrinkage in the width direction.
  • thermal contraction in the longitudinal direction can be suppressed in a mode in which the separator is wound together with a long sheet-like positive electrode and negative electrode. Therefore, the porous resin film uniaxially stretched in the longitudinal direction is particularly suitable as a material for a separator constituting such a wound electrode body.
  • the thickness of the resin layer 60 is preferably about 10 ⁇ m to 30 ⁇ m, and more preferably about 15 ⁇ m to 25 ⁇ m. In the present embodiment, the thickness of the resin layer 60 is 20 ⁇ m.
  • each thickness of the PE layer 62 and the PP layers 61 and 63 may be the same or different.
  • the thickness of the PE layer 62 is about 4 ⁇ m to 10 ⁇ m, and the thicknesses of the PP layers 61 and 63 are appropriately selected so that the total thickness of the resin layer 60 falls within the above range. If the thickness of the resin layer 60 is too large, the ion conductivity of the separator 50 may be reduced. On the other hand, if the thickness of the resin layer 60 is too small, film breakage may occur.
  • the thickness of the resin layer 60 can be calculated
  • various physical property values of the resin layer 60 are physical property values when the resin layer 60 is present alone, in other words, the resin layer 60 in a state before the heat-resistant layer 70 is laminated. Means various physical properties.
  • the porosity of the resin layer 60 means the porosity of the resin layer 60 in a state before the heat resistant layer 70 is laminated.
  • the porosity of the resin layer 60 is preferably 45% to 65% (for example, greater than 45% and less than 65%).
  • the porosity is expressed by volume%, but is simply expressed as% below.
  • the porosity of the resin layer 60 is preferably 60% to 65% (typically greater than 60% and less than 65%), and particularly preferably about 62%.
  • the porosity of the resin layer 60 is determined by the average porosity of the PP layer 61, the PE layer 62, and the PP layer 63 as a whole.
  • the porosity of the resin layer 60 is preferably 45% to 52%, particularly preferably about 47%. If the porosity of the resin layer 60 is too small, the amount of electrolyte solution that can be held in the separator decreases, and the ionic conductivity may decrease. On the other hand, if the porosity of the resin layer 60 is too large, the strength may be insufficient, and film breakage may occur easily.
  • the porosity of the resin layer 60 can be calculated as follows.
  • the apparent volume occupied by the resin layer 60 of unit area (size) is V1 [cm 3 ], and the mass of the resin layer 60 of the unit area is W [g].
  • the ratio of the mass W to the true density ⁇ [g / cm 3 ] of the resin material constituting the resin layer 60, that is, W / ⁇ is V0.
  • V0 is the volume occupied by the dense body of the resin material with mass W.
  • the porosity of the resin layer 60 can be calculated by (V1 ⁇ V0) / V1 ⁇ 100.
  • the porosity of each layer is not particularly limited.
  • the porosity of the PP layer 61 is 20% to 30%, and the porosity of the PP layer 63 is the same as that of the PP layer 61. It can be about the same.
  • the porosity of the PE layer 62 is preferably higher than the porosity of the PP layers 61 and 63, and can be, for example, about 50% to 80%.
  • maintain more electrolyte solution can be formed by making the porosity of PE layer 62 located between both PP layers 61 and 63 high.
  • the PP layers 61 and 63 having a low porosity have a relatively small heat shrinkage rate.
  • the pore volume [cm 3 / g] of the resin layer 60 is the volume [cm 3 ] of the pores contained per unit mass [g] of the resin layer 60.
  • the pore amount of the resin layer 60 decreases as the heat-resistant layer 70 is formed. That is, the pore amount of the resin layer 60 after the heat resistant layer 70 is laminated is smaller than the pore amount of the resin layer 60 before the heat resistant layer 70 is laminated. This is because when the heat-resistant layer 70 is formed on the surface of the resin layer 60, a part of the composition (heat-resistant layer forming composition) for forming the heat-resistant layer 70 enters the pores of the resin layer 60. Is presumed to be the cause.
  • Pore volume of the resin layer 60 before the heat-resistant layer 70 is laminated in other words, the pore volume when the resin layer 60 is present alone, 0.5cm 3 /g ⁇ 1.1cm 3 / g (e.g. 0.8cm 3 /g ⁇ 1.1cm 3 / g) that it is appropriate to.
  • the amount of pores in the resin layer 60 before the heat-resistant layer 70 is laminated is typically about 1.02 cm 3 / g when the resin layer 60 has a three-layer structure, and the resin layer 60 has a single-layer structure. In this case, it is about 0.85 cm 3 / g.
  • the amount of pores can be calculated based on the measurement result of the pore size distribution and the mass of the resin layer 60 by measuring the pore size distribution of the resin layer 60 using, for example, a mercury porosimeter.
  • the lithium ion mobility (ease of lithium ions passing through the separator, and thus battery characteristics) greatly affects. It is considered that the pore diameter is 0.05 ⁇ m to 2 ⁇ m. Therefore, the degree of decrease in the amount of pores in the resin layer 60 associated with the formation of the heat-resistant layer 70 is targeted only for pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m, even if not targeting pores of all sizes.
  • the pore amount of pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m in the resin layer 60 also decreases. Based on the degree of decrease, the extent to which the heat-resistant layer-forming composition has entered the pores of the resin layer 60 can be adjusted to a range in which the problem of the present invention can be effectively solved.
  • the pore volume of pores having a pore size of 0.05 .mu.m ⁇ 2 [mu] m is, for example, 0.65cm 3 /g ⁇ 0.9cm 3 / g.
  • the pore volume is typically the case where the resin layer 60 is a three-layer structure is about 0.85 cm 3 / g, when the resin layer 60 has a single-layer structure is 0.70 cm 3 / g approximately .
  • the resin layer 60 As the resin layer 60, a commercially available product (such as a commercially available porous resin sheet) having the above-described characteristics may be used as it is, or a product manufactured according to a conventionally known method may be used.
  • a commercially available product such as a commercially available porous resin sheet having the above-described characteristics may be used as it is, or a product manufactured according to a conventionally known method may be used.
  • the heat-resistant layer 70 includes a filler made of an inorganic material and a binder.
  • an inorganic material having high electrical insulation and a melting point higher than that of the PP layers 61 and 63 and the PE layer 62 (for example, 190 ° C. or higher) can be suitably used.
  • the material can be, for example, a metal oxide, hydroxide, nitride, carbonate, sulfate or the like.
  • the form of the inorganic material can be in the form of particles, fibers, flakes, and the like. Usually, it is preferable to use a particulate inorganic material. Particles made of inorganic oxide or inorganic hydroxide can be suitably used.
  • one or two or more inorganic oxides selected from alumina, boehmite, magnesia, titania, silica, zirconia, zinc oxide, iron oxide, ceria, yttria and the like can be used.
  • one or two or more inorganic hydroxides selected from magnesium hydroxide, calcium hydroxide, barium hydroxide and the like may be used.
  • Particularly preferred inorganic compounds include alumina, boehmite, magnesia, and magnesium hydroxide.
  • the primary particle diameter of the inorganic compound particles can be, for example, about 0.15 ⁇ m to 2 ⁇ m, and the specific surface area can be about 2 to 13 m 2 / g.
  • binder examples include acrylic resins (for example, those having a polymer of acrylic acid ester as a main component), polyolefin resins such as styrene butadiene rubber (SBR), PE, PP, polyvinylidene fluoride (PVDF), Halogen resins such as polytetrafluoroethylene (PTFE) and polyvinylidene chloride (PVDC) (for example, fluorine resins), cellulose resins such as carboxymethyl cellulose (CMC), and the like can be used.
  • acrylic resins for example, those having a polymer of acrylic acid ester as a main component
  • polyolefin resins such as styrene butadiene rubber (SBR), PE, PP, polyvinylidene fluoride (PVDF), Halogen resins such as polytetrafluoroethylene (PTFE) and polyvinylidene chloride (PVDC) (for example, fluorine resins), cellulose resins such as carboxy
  • the form of the binder is not particularly limited, and a particulate (powdered) form may be used as it is, or a solution or emulsion prepared may be used.
  • Two or more kinds of binders may be used in different forms.
  • a powdery or solution (aqueous solution) CMC and an emulsion acrylic resin can be used in combination.
  • the viscosity may be appropriately selected based on the desired solid content (NV), handleability, etc. of the heat-resistant layer forming composition.
  • the average particle size is not particularly limited. For example, an average particle size of about 0.05 ⁇ m to 0.5 ⁇ m can be used.
  • the mass ratio (based on NV) is about 94: 6 to 99: 1. If the blending amount of the binder is too small, the anchoring property of the heat-resistant layer 70 and the strength (shape retention) of the heat-resistant layer 70 itself may be deteriorated, resulting in defects such as cracks and peeling. When there are too many compounding quantities of the said binder, the porosity of the heat-resistant layer 70 may be insufficient, or the ion permeability of the separator 13 may fall.
  • the solid content of the heat-resistant layer forming composition is, for example, about 30% by mass to 50% by mass. The solid content is typically about 40% by weight for solvent-based materials and 50% to 52% by weight for water-based materials.
  • the solvent for dissolving or dispersing these components is not particularly limited, and examples thereof include water, alcohols such as ethanol, N-methyl-2-pyrrolidone (NMP), toluene, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and the like. Can be appropriately selected and used.
  • alcohols such as ethanol, N-methyl-2-pyrrolidone (NMP), toluene, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and the like.
  • NMP N-methyl-2-pyrrolidone
  • DMC dimethyl carbonate
  • EMC ethyl methyl carbonate
  • the heat-resistant layer-forming composition may include a surfactant, a wetting agent, a dispersing agent, a thickener, an erasing agent, as long as the function of the separator 13 and the performance of the secondary battery 10 to be manufactured are not impaired. You may mix
  • the method for applying the heat-resistant layer forming composition to the resin layer 60 is not particularly limited.
  • a die coater, gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, air knife coater, spray coater, A brush coater, a screen coater or the like can be used.
  • the drying step after coating can be performed by appropriately selecting a conventionally known method. For example, a method of holding and drying at a temperature lower than the melting point of the PE layer 62 (for example, about 80 ° C. to 100 ° C.), a method of holding and drying at a low temperature under reduced pressure, and the like can be mentioned.
  • the thickness of the heat-resistant layer 70 after drying is preferably about 1 ⁇ m to 12 ⁇ m (more preferably 2 ⁇ m to 8 ⁇ m, for example, greater than 2 ⁇ m and less than 8 ⁇ m). If the thickness of the heat-resistant layer 70 is too large, the handleability and workability of the separator 13 may be reduced, and defects such as cracks and peeling may easily occur. If the thickness is too small, the short-circuit prevention effect may be reduced, or the amount of electrolyte that can be retained may be reduced.
  • the thickness of the heat-resistant layer 70 can be obtained by image analysis of an image taken with a scanning electron microscope (SEM).
  • the porosity of the heat-resistant layer 70 is preferably 45% to 65% (for example, greater than 45% and less than 65%). If the porosity of the heat-resistant layer 70 is too large, the effect of suppressing the thermal shrinkage of the resin layer 60 may be reduced, and problems such as cracks and peeling may easily occur. On the other hand, if the porosity of the heat-resistant layer 70 is too small, the ion conductivity of the separator 50 may be reduced.
  • the porosity of the heat resistant layer 70 can also be calculated in the same manner as the porosity of the resin layer 60. That is, the apparent volume occupied by the heat-resistant layer 70 having a unit area is defined as V1 [cm 3 ].
  • the porosity of the heat-resistant layer 70 can be calculated by (V1 ⁇ V0) / V1 ⁇ 100.
  • the thickness of the heat-resistant layer 70 is necessary when calculating the apparent volume V1, and the thickness can be obtained by image analysis of an image taken with a scanning electron microscope (SEM).
  • the mass W of the heat-resistant layer 70 can be measured as follows. That is, the separator 13 is cut out to a predetermined area (for example, 6.1 cm ⁇ 7.3 cm) to obtain a sample, and the mass thereof is measured. Next, the mass of the heat-resistant layer 70 having the predetermined area is calculated by subtracting the mass of the resin layer 60 having the predetermined area from the mass of the sample. The mass W [g] of the heat-resistant layer 70 can be calculated by converting the mass of the heat-resistant layer 70 thus calculated per unit area.
  • a predetermined area for example, 6.1 cm ⁇ 7.3 cm
  • the thickness of the separator 13 as a whole increases as the heat-resistant layer 70 is formed.
  • the electrical resistance of the separator 13 increases.
  • a part of the heat-resistant layer-forming composition (binder) enters the pores of the resin layer 60. Therefore, the amount of pores in the resin layer 60 decreases. Therefore, it is expected that the electrical resistance of the resin layer 60 itself increases and the electrical resistance of the separator 13 further increases.
  • the present inventor has found that the electric resistance of the separator 13 does not increase so much depending on how the heat-resistant layer 70 is formed. The reason is considered as follows.
  • the surface 80 of the pores is rough (a state in which resin fuzz, fibrils, etc. are exposed as they are) as shown in FIG. 4A.
  • the roughness of the surface 80 can be a factor that hinders the smooth movement of the lithium ions 90.
  • a part (binder) of the heat-resistant layer forming composition enters the pores of the resin layer 60, the surface of the pores is coated with the composition 75 as shown in FIG. 80 is considered to be smooth.
  • the movement of the lithium ions 90 becomes smooth. Therefore, it is presumed that the increase in the electrical resistance of the separator 13 can be kept low despite the increase in the thickness of the entire separator 13 and the decrease in the amount of pores in the resin layer 60.
  • the resin layer 60 is in the pores of the resin layer 60 in the laminated state. Measurement accuracy because at least part of the component derived from the composition for forming the heat-resistant layer (such as a binder that has entered the pores of the resin layer 60 when the heat-resistant layer 70 is laminated) is easily removed together with the heat-resistant layer 70.
  • the pore amount A [cm 3 / g] of only the resin layer 60 that is, the resin layer 60 before the heat-resistant layer 70 is laminated
  • the heat-resistant layer 70 after the lamination are laminated.
  • the pore volume ratio is preferably 60% to 90%, more preferably 70% to 90%, and even more preferably about 80%. If the pore volume ratio is too small, the porosity of the resin layer 60 becomes too small, so that the effect of narrowing the ion conduction path is superior to the effect of smoothing the surface of the pores of the resin layer 60. There is a possibility that the electrical resistance of 13 will increase greatly. On the other hand, if the pore amount ratio is too large, the effect of smoothing the surface of the pores of the resin layer 60 cannot be obtained sufficiently. Moreover, since the large pore amount ratio means that the coating amount of the heat-resistant layer forming composition is small, if the pore amount ratio is too large, the heat-resistant layer 70 is sufficiently formed on the resin layer 60. There is a possibility that the thermal contraction of the resin layer 60 cannot be effectively suppressed.
  • the pore volume ratio of pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m is also preferably 60% to 90%, more preferably 70% to 90%, and even more preferably about 80%.
  • Pore volume of the separator 13, i.e., the average pore volume of the entire resin layer 60 and the heat-resistant layer 70 is, for example, 0.4cm 3 /g ⁇ 1.0cm 3 / g, typically 0.55 cm 3 / G to 0.90 cm 3 / g.
  • Pore volume of the separator 13 of the resin layer 60 is a three-layer structure is typically a 0.61cm 3 /g ⁇ 0.90cm 3 / g.
  • Pore volume of the separator 13 of the resin layer 60 is a single layer structure is typically a 0.55cm 3 /g ⁇ 0.76cm 3 / g.
  • Pore volume of pores having a pore size of 0.05 .mu.m ⁇ 2 [mu] m in the separator 50 is, for example, 0.4cm 3 /g ⁇ 1.0cm 3 / g, typically 0.46cm 3 / g ⁇ 0 0.73 cm 3 / g.
  • the pore volume is, for example, 0.53cm 3 /g ⁇ 0.73cm 3 / g.
  • the pore volume is, for example, 0.46cm 3 /g ⁇ 0.62cm 3 / g.
  • the separator 13 can be manufactured as follows. First, a porous resin film having a predetermined thickness (for example, 10 ⁇ m to 30 ⁇ m) and a porosity of 45% to 65% is prepared (first step). Such a porous resin film may be produced, or a commercially available porous resin film may be used as it is. This porous resin film is preferably a uniaxially or biaxially stretched film. The porous resin film may be a PP-PE-PP three-layer film or a PE single-layer film.
  • an inorganic filler, a binder, an appropriate amount of solvent, and a thickener as necessary are added and kneaded using a kneader or the like to prepare a slurry or paste-like composition for forming a heat-resistant layer.
  • the porosity of the heat-resistant layer formed by the above composition is 45% to 65%, and the pore volume ratio (typically a pore diameter of 0.05 ⁇ m to 2 ⁇ m).
  • the above composition is applied to the surface of the porous resin film and dried (third step) so that the pore volume ratio of the pores having the pores is 60% to 90%.
  • the lithium ion secondary battery 10 can be used as a secondary battery for various applications.
  • a secondary battery for various applications.
  • it can be suitably used as a power source for a motor (electric motor) mounted on a vehicle 1 such as an automobile.
  • vehicle 1 such as an automobile.
  • vehicle 1 is not specifically limited, Typically, they are a hybrid vehicle, an electric vehicle, a fuel cell vehicle, etc.
  • Such lithium ion secondary battery 10 may be used alone, or may be used in the form of an assembled battery that is connected in series and / or in parallel.
  • Example 1 A PP-PE-PP three-layer film having a thickness of 20 ⁇ m and a porosity of 45% was used as the resin layer of Example 1.
  • alumina powder manufactured by Sumitomo Chemical Co., Ltd., “AKP3000”
  • an acrylic binder product of Nippon Zeon Co., Ltd.
  • an appropriate amount of NMP manufactured by Kanto Chemical Co., Ltd.
  • the solid content was kneaded with a kneader (disperser “CLEAMIX” manufactured by M Technique Co., Ltd.) so as to be 50% by mass to prepare a slurry for forming a heat-resistant layer.
  • the preliminary dispersion (15000 rpm) was 5 minutes and the main dispersion (20000 rpm) was 15 minutes.
  • the weight ratio between the filler and the binder in the solid content was adjusted to 96: 4, and the total mixing amount was adjusted to 1 kg.
  • a vibration viscometer (“VISCOMETER VM-100A-L” manufactured by CBC Co., Ltd.)
  • the viscosity of the slurry was measured at a temperature of 22 ° C. to 28 ° C. and found to be 119 mPa ⁇ s.
  • the slurry was applied to the resin layer using a gravure coating method and dried to form a heat-resistant layer.
  • a gravure roll having a number of lines of 100 / inch and a cell volume of 19.5 cc / m 2 was used.
  • the line (coating) speed was 3 m / min
  • the gravure roll speed was 3.8 m / min
  • the speed ratio was 1.27.
  • the drying temperature was 80 ° C.
  • a sample having a size of 3 cm ⁇ 2 cm was cut from the separator obtained as described above.
  • a total of 30 samples were placed in a cell of a mercury porosimeter (“Autopore III9410” manufactured by Shimadzu Corporation), and the pore size distribution was measured in a pressure range of 20 to 20000 psia.
  • the amount of pores was determined from the measurement result of the pore size distribution and the mass of the sample.
  • the pore volume ratio was calculated from the pore volume of the resin layer determined in the same manner and the pore volume of the separator.
  • the pore volume ratio (referred to as the total pore volume ratio) for all pores (regardless of pore diameter) is 60%, and the pore volume of pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m. The ratio was 62%.
  • Example 2 A PP-PE-PP three-layer film having a thickness of 20 ⁇ m and a porosity of 45% was used as the resin layer of Example 2.
  • alumina powder manufactured by Sumitomo Chemical Co., Ltd., “AKP3000” was used. SBR was used as the binder. Water was used as a solvent. CMC was used as a thickener. Using a kneader (Disper Disperser “ROBO MICS” manufactured by Tokushu Kika Co., Ltd.), 0.7% by mass of CMC was synthesized. The dispersion at 8000 rpm was performed for 1 hour, and then stored sealed at room temperature for 1 day.
  • Example 2 In the same manner as in Example 1, the slurry was applied to the resin layer and dried.
  • the total pore volume ratio was 70%, and the pore volume ratio of pores having a pore diameter of 0.05 ⁇ m to 2 ⁇ m (hereinafter simply referred to as “pore volume ratio”) was 72%.
  • Example 3 A filler, a binder, a solvent, and a thickener so that the NV becomes 35% by mass in the same manner as in Example 2 except that a polyolefin-based binder (a polypropylene-based binder having a particle size of 100 nm to 400 nm) is used as a solvent.
  • a polyolefin-based binder a polypropylene-based binder having a particle size of 100 nm to 400 nm
  • a slurry was adjusted so that the weight ratio of the filler in a solid content, a binder, and a thickener might be 96.7: 2.6: 0.7, and a mixing total amount would be 1 kg.
  • the viscosity of the slurry was 35 mPa ⁇ s.
  • the slurry was applied to the resin layer and dried.
  • the total pore volume ratio was 83%, and the pore volume ratio was 84%.
  • Example 4 Except that the porosity of the resin layer was 52%, magnesium hydroxide (manufactured by Kamishima Chemical Co., Ltd.) was used as the filler, and the NV of the slurry was 49% by mass, A separator was produced. The viscosity of the slurry was 115 mPa ⁇ s. The total pore volume ratio was 62%, and the pore volume ratio was 64%.
  • Example 5 Except that the porosity of the resin layer was 52%, magnesium hydroxide (manufactured by Kamishima Chemical Co., Ltd.) was used as the filler, and the NV of the slurry was 40% by mass, A separator was produced. The viscosity of the slurry was 52.9 mPa ⁇ s. The total pore volume ratio was 75%, and the pore volume ratio was 77%.
  • Example 6 Except that the porosity of the resin layer was 52%, magnesium hydroxide (manufactured by Kamishima Chemical Co., Ltd.) was used as the filler, and the NV of the slurry was 34% by mass, A separator was produced. The viscosity of the slurry was 33 mPa ⁇ s. The total pore volume ratio was 88%, and the pore volume ratio was 86%.
  • Example 7 A PE single layer film having a thickness of 20 ⁇ m and a porosity of 60% was used as the resin layer, boehmite (“C20” manufactured by Daimei Chemical Co., Ltd.) was used as the filler, and the slurry had an NV of 48% by mass.
  • a separator was produced in the same manner as Example 1 except for the above. The viscosity of the slurry was 110 mPa ⁇ s. The total pore volume ratio was 65%, and the pore volume ratio was 66%.
  • Example 8> A separator was produced in the same manner as in Example 7 except that the NV of the slurry was 40% by mass.
  • the viscosity of the slurry was 42 mPa ⁇ s.
  • the total pore volume ratio was 77%, and the pore volume ratio was 79%.
  • Example 9 A separator was produced in the same manner as in Example 7 except that the NV of the slurry was 33% by mass.
  • the viscosity of the slurry was 32 mPa ⁇ s.
  • the total pore volume ratio was 89%, and the pore volume ratio was 87%.
  • Example 10 Example except that a PE single layer film having a thickness of 20 ⁇ m and a porosity of 65% was used as the resin layer, magnesia (manufactured by Kamishima Chemical Co., Ltd.) was used as the filler, and the NV of the slurry was 47% by mass.
  • a separator was produced in the same manner as in Example 1, a separator was produced.
  • the viscosity of the slurry was 80 mPa ⁇ s.
  • the total pore volume ratio was 69%, and the pore volume ratio was 70%.
  • Example 11 A separator was produced in the same manner as in Example 10 except that the NV of the slurry was 39% by mass.
  • the viscosity of the slurry was 40 mPa ⁇ s.
  • the total pore volume ratio was 80%, and the pore volume ratio was 82%.
  • Example 12 A separator was produced in the same manner as in Example 10 except that the NV of the slurry was 32% by mass.
  • the viscosity of the slurry was 30 mPa ⁇ s.
  • the total pore volume ratio was 90%, and the pore volume ratio was 88%.
  • Example 1 A separator was prepared in the same manner as in Example 1 except that a PP-PE-PP three-layer film having a thickness of 20 ⁇ m and a porosity of 44% was used as the resin layer, and the NV of the slurry was 52 mass%. did. The viscosity of the slurry was 131 mPa ⁇ s. The total pore volume ratio was 56%, and the pore volume ratio was 58%.
  • Example 2 A separator was prepared in the same manner as in Example 1 except that a PP-PE-PP three-layer film having a thickness of 20 ⁇ m and a porosity of 42% was used as the resin layer, and the NV of the slurry was 53% by mass. did. The viscosity of the slurry was 136 mPa ⁇ s. The total pore volume ratio was 53%, and the pore volume ratio was 55%.
  • Example 3 A separator was produced in the same manner as in Example 1 except that a PE single layer film having a thickness of 20 ⁇ m and a porosity of 67% was used as the resin layer, and the NV of the slurry was 29% by mass. The viscosity of the slurry was 21 mPa ⁇ s. The total pore volume ratio was 93%, and the pore volume ratio was 90%.
  • a separator was produced in the same manner as in Example 1 except that a PE single layer film having a thickness of 20 ⁇ m and a porosity of 68% was used as the resin layer, and the NV of the slurry was 28% by mass.
  • the viscosity of the slurry was 19 mPa ⁇ s.
  • the total pore volume ratio was 95%, and the pore volume ratio was 94%.
  • Comparative Example 5 the separator is formed of only the resin layer. In Comparative Example 5, the heat-resistant layer is not formed.
  • the resin layer a PP-PE-PP three-layer film having a thickness of 20 ⁇ m and a porosity of 47% was used.
  • Comparative Example 6 the separator is formed only of the resin layer.
  • a PE single layer film having a thickness of 20 ⁇ m and a porosity of 47% was used as the resin layer.
  • the positive electrode active material As the positive electrode active material, it was used lithium composite oxide powder represented by LiNi 1/3 Co 1/3 Mn 1/3 O 2 .
  • This positive electrode active material, acetylene black as a conductive material, and PVDF as a binder are mixed with NMP so that the mass ratio of these materials is 87: 10: 3 and NV is about 40% by mass,
  • a slurry-like composition for forming a positive electrode mixture layer was prepared. This composition was applied to both sides of a 15 ⁇ m thick long aluminum foil (current collector) and dried to form a positive electrode mixture layer. The coating amount (solid content basis) of the composition was adjusted so that the total coating amount on both sides was about 12.8 mg / cm 2 . Next, the current collector and the positive electrode mixture layers on both sides thereof were pressed so that the total thickness became 74 ⁇ m. In this way, a positive electrode sheet was produced.
  • (Negative electrode sheet) Carbonaceous powder having amorphous carbon coated on the surface of graphite particles, SBR as a binder, and CMC as a thickener, the mass ratio of these materials is 98: 1: 1, and NV is 45% by mass.
  • the slurry was mixed with ion-exchanged water to prepare a slurry-like composition for forming a negative electrode mixture layer.
  • This composition was applied to both sides of a long copper foil (negative electrode current collector) having a thickness of about 10 ⁇ m and dried.
  • the coating amount (solid content basis) of the composition was adjusted so that the total coating amount on both sides was about 8 mg / cm 2 . After drying, pressing was performed so that the total thickness was 65 ⁇ m. In this way, a negative electrode sheet was produced.
  • Nonaqueous electrolyte As the non-aqueous solvent, a solvent composed of ethylene carbonate (EC) and diethyl carbonate (DEC) was used. The mass ratio of EC to DEC is 3: 7. In the above solvent, 1M-LiPF 6 was dissolved as a lithium salt to prepare a non-aqueous electrolyte.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • a positive electrode sheet, a negative electrode sheet, and two separators were overlapped and wound into a cylindrical shape to obtain an electrode body.
  • the electrode body is accommodated in a bottomed cylindrical case body made of nickel-plated mild steel having a diameter of 18 mm, a length of 65 mm, and a thickness of 0.5 mm, and after sealing with a nonaqueous electrolyte, a battery is manufactured. did.
  • Tables 1 and 2 summarize the outlines of separator production according to Examples 1 to 12 and Comparative Examples 1 to 6, materials used, and outlines of the obtained separators.
  • the initial internal resistance value (IV resistance value) of each battery using the separators of Examples 1 to 12 and Comparative Examples 1 to 6 was measured. First, each battery was adjusted to a SOC (State of Charge) 60% charge state by constant current constant voltage (CC-CV) charging in an environmental atmosphere of 25 ° C. Then, discharge was performed at 25 ° C. with current values of 0.3 C, 1 C, and 3 C for 10 seconds, and a voltage value 10 seconds after the start of discharge was measured. Each measurement point (current value (I), voltage value (V)) is plotted on the IV characteristic graph (horizontal axis (X axis) is I and vertical axis (Y axis) is V).
  • SOC State of Charge
  • CC-CV constant current constant voltage
  • “Initial resistance increase rate” in Table 2 is a separator without a heat-resistant layer (Comparative Example 5 when the resin layer is a PP-PE-PP three-layer film and Comparative Example when the resin layer is a PE single-layer film) 6) is the rate of increase of the initial resistance based on the initial resistance of the battery.
  • the initial resistance increase rate (R ⁇ R 0 ) / R 0 ⁇ 100.
  • the initial resistance increase rate represents how much the initial resistance of the battery has increased by adding a heat-resistant layer to the resin layer of the separator. Therefore, the lower the initial resistance increase rate, the more the battery performance is suppressed. From Table 2, it can be seen that in Examples 1 to 12, the initial resistance increase rate is 4% or less, which is smaller than those in Comparative Examples 1 to 3. According to Examples 1 to 12, battery performance (charge / discharge characteristics, high rate characteristics, etc.) can be maintained satisfactorily.

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Abstract

L'invention concerne un séparateur permettant de fabriquer une batterie secondaire lithium-ion présentant d'excellentes caractéristiques et une prévention de surchauffe, et une batterie dotée dudit séparateur. Le séparateur (13) est composé d'une couche de résine poreuse (60) et d'une couche thermorésistante poreuse (70) contenant une charge inorganique et un liant. La porosité de la couche de résine (60) avant la stratification de la couche thermorésistante (70) et la porosité de la couche thermorésistante (70) dans le séparateur (13) sont toutes deux de 45% à 65%. Si la quantité de pores A représente le volume des pores de diamètre de 0,05μm à 2μm dans la couche de résine (60) avant la stratification de la couche thermorésistante (70), et si la quantité de pores B représente le volume des pores de diamètre de 0,05μm à 2μm dans le séparateur (13), le rapport de la quantité de pores défini par B/A*100 est de 60% à 90%.
PCT/JP2010/064004 2010-08-19 2010-08-19 Batterie secondaire lithium-ion et séparateur utilisé dans ladite batterie WO2012023197A1 (fr)

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WO2014083988A1 (fr) * 2012-11-30 2014-06-05 帝人株式会社 Séparateur pour batteries secondaires non aqueuses, et batterie secondaire non aqueuse
JP2014120214A (ja) * 2012-12-13 2014-06-30 Toyota Motor Corp 非水電解液二次電池
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EP3232494A4 (fr) * 2014-12-09 2018-05-16 Toray Industries, Inc. Séparateur pour élément secondaire, procédé de fabrication de séparateur pour élément secondaire, et élément secondaire
US10276849B2 (en) 2013-06-27 2019-04-30 Asahi Kasei E-Materials Corporation Separator including polyolefin microporous membrane and inorganic porous layer, and nonaqueous electrolyte battery using the same
CN113678312A (zh) * 2019-06-04 2021-11-19 帝人株式会社 非水系二次电池用隔膜及非水系二次电池
WO2022090862A1 (fr) * 2020-10-26 2022-05-05 株式会社半導体エネルギー研究所 Séparateur, élément secondaire et procédé de production de séparateur
CN114639919A (zh) * 2022-03-24 2022-06-17 河北金力新能源科技股份有限公司 圆柱电池涂覆隔膜及其制备方法

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JP2010517811A (ja) * 2007-02-05 2010-05-27 エルジー・ケム・リミテッド 多孔性活性層がコーティングされた有機／無機複合分離膜及びこれを備えた電気化学素子
WO2009044741A1 (fr) * 2007-10-03 2009-04-09 Hitachi Maxell, Ltd. Séparateur d'accumulateur et accumulateur à electrolyte non aqueux
WO2009096451A1 (fr) * 2008-01-29 2009-08-06 Hitachi Maxell, Ltd. Suspension épaisse pour former une couche isolante, séparateur pour dispositif électrochimique, procédé pour produire celui-ci et dispositif électrochimique
JP2010015917A (ja) * 2008-07-07 2010-01-21 Hitachi Maxell Ltd 電池用セパレータおよび非水電解液電池
JP2010092881A (ja) * 2008-08-19 2010-04-22 Teijin Ltd 非水系二次電池用セパレータ

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US10347892B2 (en) 2012-11-30 2019-07-09 Teijin Limited Separator for non-aqueous secondary battery and non-aqueous secondary battery
JP5657177B2 (ja) * 2012-11-30 2015-01-21 帝人株式会社 非水系二次電池用セパレータ及び非水系二次電池
WO2014083988A1 (fr) * 2012-11-30 2014-06-05 帝人株式会社 Séparateur pour batteries secondaires non aqueuses, et batterie secondaire non aqueuse
JPWO2014083988A1 (ja) * 2012-11-30 2017-01-05 帝人株式会社 非水系二次電池用セパレータ及び非水系二次電池
US10074840B2 (en) 2012-11-30 2018-09-11 Teijin Limited Separator for non-aqueous secondary battery and non-aqueous secondary battery
JP2014120214A (ja) * 2012-12-13 2014-06-30 Toyota Motor Corp 非水電解液二次電池
JP2015005355A (ja) * 2013-06-19 2015-01-08 株式会社Ｇｓユアサ 蓄電素子
US10276849B2 (en) 2013-06-27 2019-04-30 Asahi Kasei E-Materials Corporation Separator including polyolefin microporous membrane and inorganic porous layer, and nonaqueous electrolyte battery using the same
EP3232494A4 (fr) * 2014-12-09 2018-05-16 Toray Industries, Inc. Séparateur pour élément secondaire, procédé de fabrication de séparateur pour élément secondaire, et élément secondaire
JP2016201255A (ja) * 2015-04-10 2016-12-01 トヨタ自動車株式会社 非水電解質二次電池
CN113678312A (zh) * 2019-06-04 2021-11-19 帝人株式会社 非水系二次电池用隔膜及非水系二次电池
EP3919269A4 (fr) * 2019-06-04 2022-08-03 Teijin Limited Séparateur pour batterie secondaire non aqueuse, et batterie secondaire non aqueuse
EP4235891A3 (fr) * 2019-06-04 2023-11-29 Teijin Limited Séparateur pour batterie secondaire non aqueuse, et batterie secondaire non aqueuse
WO2022090862A1 (fr) * 2020-10-26 2022-05-05 株式会社半導体エネルギー研究所 Séparateur, élément secondaire et procédé de production de séparateur
CN114639919A (zh) * 2022-03-24 2022-06-17 河北金力新能源科技股份有限公司 圆柱电池涂覆隔膜及其制备方法
CN114639919B (zh) * 2022-03-24 2024-03-22 河北金力新能源科技股份有限公司 圆柱电池涂覆隔膜及其制备方法

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