WO2018168835A1 - Séparateur de piles, corps d'électrode et pile secondaire à électrolyte non aqueux - Google Patents

Séparateur de piles, corps d'électrode et pile secondaire à électrolyte non aqueux Download PDF

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Publication number
WO2018168835A1
WO2018168835A1 PCT/JP2018/009674 JP2018009674W WO2018168835A1 WO 2018168835 A1 WO2018168835 A1 WO 2018168835A1 JP 2018009674 W JP2018009674 W JP 2018009674W WO 2018168835 A1 WO2018168835 A1 WO 2018168835A1
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Prior art keywords
copolymer
separator
polyolefin
mass
vinylidene fluoride
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PCT/JP2018/009674
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English (en)
Japanese (ja)
Inventor
辻本　潤
水野　直樹
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東レ株式会社
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Priority to KR1020197020050A priority Critical patent/KR102231395B1/ko
Priority to JP2019506037A priority patent/JP7330885B2/ja
Priority to CN201880010166.8A priority patent/CN110249449B/zh
Publication of WO2018168835A1 publication Critical patent/WO2018168835A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426—Fluorocarbon polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • 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
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • 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
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/494—Tensile strength
    • 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, an electrode body, and a nonaqueous electrolyte secondary battery.
  • Non-aqueous electrolyte secondary batteries are widely used in small electronic devices such as mobile phones and portable information terminals.
  • Examples of the form of the nonaqueous electrolyte secondary battery include a cylindrical battery, a square battery, and a laminate battery.
  • these batteries have a configuration in which an electrode body in which a positive electrode and a negative electrode are arranged via a separator, and a nonaqueous electrolytic solution are housed in an exterior body.
  • Examples of the structure of the electrode body include a laminated electrode body in which a positive electrode and a negative electrode are stacked via a separator, and a wound electrode body in which the positive electrode and the negative electrode are spirally wound via a separator.
  • microporous membranes mainly made of polyolefin resin are used as battery separators. Since the microporous membrane made of polyolefin resin has a so-called shutdown function, the current flow can be suppressed and ignition can be prevented by closing the pores of the separator when the battery is abnormally heated.
  • Patent Document 1 includes a positive electrode, a negative electrode, a three-layer separator made of polypropylene, polyethylene, and polypropylene, and an adhesive resin layer made of polyvinylidene fluoride and alumina powder disposed between the electrode and the separator.
  • An electrode body provided with is described.
  • Example 1 of Patent Document 2 VdF-HFP copolymer (HFP unit 0.6 mol%) and VdF-HFP copolymer (weight average molecular weight 470,000, HFP unit 4.8 mol%) were used. There is described a separator in which a porous layer is formed by dissolving in a dimethylacetamide and tripropylene glycol solution and applying this to a polyethylene microporous membrane.
  • Example 1 of Patent Document 3 PVdF (weight average molecular weight 500,000) and VdF-HFP copolymer (weight average molecular weight 400,000, HFP unit 5 mol%) were dissolved in dimethylacetamide and tripropylene glycol solution. A separator in which a porous layer is formed by applying this to a polyethylene microporous film is described.
  • Example 1 of Patent Document 4 PVdF (weight average molecular weight: 700,000) and VdF-HFP copolymer (weight average molecular weight: 470,000, HFP unit: 4.8 mol%) were mixed in dimethylacetamide and tripropylene glycol solution.
  • a separator is described in which a porous layer is formed by dissolving the polymer in a polyethylene microporous film.
  • Example 1 of Patent Document 5 PVdF (weight average molecular weight 350,000) and VdF-HFP copolymer (weight average molecular weight 270,000, HFP copolymer 4.8 mol%) were mixed with dimethylacetamide and tripropylene glycol.
  • a separator is disclosed in which a porous layer is formed by dissolving in a solution and coating it on a polyethylene microporous membrane.
  • Example 23 of Patent Document 6 a VdF-HFP copolymer (weight average molecular weight 1.93 million, HFP unit 1.1 mol%) and a VdF-HFP copolymer (weight average molecular weight 470,000, HFP unit 4. 8 mol%) is dissolved in a dimethylacetamide and tripropylene glycol solution, and a coating solution is prepared by adding aluminum hydroxide, and this is applied to a polyethylene microporous membrane to form a separator having a porous layer.
  • a coating solution is prepared by adding aluminum hydroxide
  • Patent Documents 1 to 5 all improve the adhesion between the separator containing the electrolytic solution and the electrode. However, when the secondary battery is enlarged, further improvement in the adhesion is required.
  • the present inventors evaluated the adhesion between the electrode and the separator when the adhesion between the electrode and the separator during drying and the adhesion between the electrode and the separator when wet. Focusing on the fact that the adhesiveness can be more accurately evaluated by distinguishing and evaluating two types of adhesiveness, and further, using these adhesivenesses as indicators of peel strength when dry and bending strength when wet, respectively. And found that it can be evaluated.
  • the wound electrode body is manufactured by winding a positive electrode and a negative electrode while applying tension to each member via a separator.
  • the positive electrode and the negative electrode applied to the metal current collector hardly expand or contract with respect to the tension, but the separator is wound while extending to some extent in the machine direction.
  • the separator portion is gradually contracted to return to the original length.
  • a force in the parallel direction is generated at the boundary surface between the electrode and the separator, and the wound electrode body (particularly, the electrode body wound flatly) is likely to bend and distort.
  • the separator In order to suppress the occurrence of deflection and distortion of the wound electrode body, the separator is required to have more adhesiveness with the electrode than ever before. Further, when the electrode body is transported, the electrodes and the separator are peeled off unless the respective members are sufficiently bonded, and cannot be transported with a high yield. The problem of adhesion at the time of transportation becomes obvious due to the increase in size of the battery, and there is a concern that the yield may deteriorate. Therefore, the separator is required to have a high peeling force during drying that is difficult to peel off from the electrode.
  • the adhesion between the polyolefin microporous film and the porous layer is also extremely important.
  • the separator is required to have high adhesion between the polyolefin microporous membrane and the porous layer.
  • the tape peeling force obtained by the measuring method mentioned later about this adhesiveness was made into the parameter
  • the yield of the porous layer will be improved by preventing the porous layer from falling off during handling of the separator and during transportation after coating.
  • the separator is required to have adhesiveness with the electrode in the battery after injecting the electrolytic solution. In this specification, this adhesiveness is evaluated using as an index the wet bending strength obtained by the measurement method described later.
  • the measurement method of the bending strength when wet described later can show the difficulty of lateral displacement between the laminated electrode and the separator in the electrode body wet with the electrolyte, and the separator in a state containing the electrolyte
  • Adhesiveness with an electrode can be evaluated according to an actual battery. If this strength is large, it can be considered that improvement of battery characteristics such as suppression of battery swelling after repeated charge and discharge is expected.
  • the peeling force at the time of drying represents the adhesiveness to the interface between the separator and the electrode when the separator does not substantially contain the electrolyte.
  • that electrolyte solution does not contain substantially means that the electrolyte solution in a separator is 500 ppm or less.
  • the battery is required to have a characteristic in which the convex portion of the electrode active material penetrates the separator and the electrode is not easily short-circuited (hereinafter referred to as short-circuit resistance) even when a sudden impact is applied.
  • short-circuit resistance a characteristic in which the convex portion of the electrode active material penetrates the separator and the electrode is not easily short-circuited
  • the battery separator is expected to have a thin film thickness.
  • the thickness of the separator decreases, it becomes difficult to ensure short circuit resistance.
  • it is known that it is effective to contain a certain amount or more of inorganic particles in the porous layer, but when including inorganic particles that can ensure short circuit resistance, There is a tendency for the adhesion of the resin to decrease.
  • the present invention has been made in view of the above circumstances, and is excellent in both the adhesion between the electrode and the separator when dried and the adhesion between the electrode and the separator when wet, and the polyolefin microporous membrane and the porous interlayer
  • Another object of the present invention is to provide a battery separator that is excellent in the adhesive property of the battery and has excellent short circuit resistance, and an electrode body and a secondary battery using the battery separator.
  • the inventors of the present invention have developed a first microporous layer made of a specific first polyolefin resin and a second microporous layer made of a second polyolefin resin.
  • the above-mentioned problem can be solved by a separator including at least a polyolefin multilayer microporous membrane containing a porous layer containing two types of fluororesins having different structures in a specific amount and a specific amount of inorganic particles.
  • the present invention is a battery separator comprising a polyolefin microporous membrane and a porous layer on at least one surface of the polyolefin microporous membrane
  • the polyolefin microporous membrane comprises a polyolefin multilayer microporous membrane having a three-layer structure in which the first microporous layer / second microporous layer / first microporous layer are laminated in this order.
  • the first microporous layer is made of a first polyolefin resin containing polyethylene and polypropylene, and the content of the polypropylene is 10% by mass or more and 50% by mass with respect to the total mass of the first polyolefin resin.
  • the second microporous layer is made of only polyethylene resin
  • the porous layer includes a vinylidene fluoride-hexafluoropropylene copolymer (A), a vinylidene fluoride-hexafluoropropylene copolymer (B), and inorganic particles
  • the vinylidene fluoride-hexafluoropropylene copolymer (A) has not less than 0.3 mol% and not more than 5.0 mol% of hexafluoropropylene units, and has a weight average molecular weight of not less than 900,000 and not more than 2 million, And includes a hydrophilic group
  • the vinylidene fluoride-hexafluoropropylene copolymer (B) has more than 5.0 mol% and not more than 8.0 mol% hexafluoropropylene units, and has a weight average molecular weight of 100,000 to 750,000,
  • the vinylidene fluoride-hexafluoropropylene copolymer (A) preferably contains 0.1 mol% or more and 5.0 mol% or less of a hydrophilic group.
  • the vinylidene fluoride-hexafluoropropylene copolymer (B) preferably has a melting point of 60 ° C. or higher and 145 ° C. or lower.
  • the inorganic particles are preferably at least one selected from titanium dioxide, alumina, and boehmite.
  • the present invention is also an electrode body comprising a positive electrode, a negative electrode, and the battery separator of the present invention.
  • the present invention is also a non-aqueous electrolyte secondary battery comprising the electrode body of the present invention and a non-aqueous electrolyte.
  • both the adhesion between the electrode and the separator at the time of drying and the adhesion between the electrode and the separator at the time of wetness are excellent, and the adhesion between the polyolefin multilayer microporous membrane and the porous layer, and A separator excellent in short circuit resistance, and an electrode body and a secondary battery using the separator are provided.
  • FIG. 1 is a schematic diagram illustrating an example of a battery separator according to the present embodiment.
  • FIG. 2 is a schematic view showing an example of the battery separator of the present embodiment.
  • FIG. 3 is a schematic diagram showing a method for evaluating the bending strength when wet.
  • FIG. 4 is a schematic diagram showing an evaluation method for a short-circuit resistance test.
  • FIG.1 and FIG.2 is a figure which shows an example of the separator which concerns on this embodiment.
  • a battery separator 10 (hereinafter sometimes abbreviated as “separator 10”) includes a polyolefin microporous membrane 1 and a porous layer laminated on at least one surface of the polyolefin microporous membrane 1.
  • the polyolefin microporous membrane 1 includes a polyolefin multilayer microporous structure having a three-layer structure in which a first microporous layer a / second microporous layer b / first microporous layer a are laminated in this order. It can consist of membrane 1 '.
  • each layer constituting the battery separator will be described.
  • the first microporous layer a is composed of a first polyolefin resin containing polyethylene and polypropylene.
  • the first polyolefin resin is preferably composed mainly of polypropylene and polyethylene.
  • having polypropylene and polyethylene as main components means that polypropylene and polyethylene are contained in an amount of 95% or more, preferably 99% by mass or more, based on the total mass of the first polyolefin resin.
  • a high density polyethylene is a main component from a viewpoint of strength.
  • the lower limit of the weight average molecular weight (hereinafter referred to as Mw) of the high-density polyethylene is preferably 1 ⁇ 10 5 or more, more preferably 2 ⁇ 10 5 or more.
  • the upper limit of the Mw of the high density polyethylene is preferably 8 ⁇ 10 5 or less, more preferably 7 ⁇ 10 5 or less.
  • the first microporous layer a contains polypropylene.
  • polypropylene is added to the first microporous layer a, the peel strength (adhesiveness) between the polyolefin multilayer microporous membrane 1 'and the porous layer 2 is further improved, and when used as a battery separator, meltdown The temperature can be further improved.
  • a block copolymer and a random copolymer can be used in addition to the homopolymer.
  • the block copolymer and random copolymer can contain a copolymer component with an ⁇ -olefin other than propylene, and ethylene is preferable as the other ⁇ -olefin.
  • the lower limit of Mw of polypropylene is preferably 5 ⁇ 10 5 or more, more preferably 6.5 ⁇ 10 5 or more, and still more preferably 8 ⁇ 10 5 or more.
  • Mw of the polypropylene is within the above range, a film having a uniform film thickness can be obtained without deteriorating the dispersibility of the polypropylene during sheet formation.
  • the upper limit of Mw of a polypropylene is not specifically limited, For example, it is 2 * 10 ⁇ 6 > or less.
  • the content of polypropylene is preferably 10% by mass or more and 50% by mass or less with respect to the total mass of the first polyolefin resin. When the content of polypropylene exceeds 50% by mass, ion permeability may be deteriorated.
  • the lower limit of the polypropylene content is preferably 15% by mass or more, and more preferably 20% by mass or more. When the content of polypropylene is in the above range, both excellent adhesion between the polyolefin multilayer microporous membrane 1 ′ and the porous layer 2, and good meltdown characteristics and ion permeability can be achieved.
  • the second microporous layer b is made of only a polyethylene resin.
  • being made of only a polyethylene resin means that the polyethylene resin is 99% by mass or more. This is because contaminants derived from foreign substances and dirt adhering to the raw resin or polyolefin microporous membrane manufacturing process lines and equipment may be peeled off and mixed into the membrane.
  • the type of polyethylene used in the second microporous layer b high density polyethylene such as density exceeding 0.94 g / cm 3, density polyethylene in the range density of 0.93 ⁇ 0.94g / cm 3 , Low density polyethylene having a density lower than 0.93 g / cm 3 , linear low density polyethylene, ultrahigh molecular weight polyethylene, and the like. From the viewpoint of strength, high density polyethylene and ultra high molecular weight polyethylene may be contained. preferable.
  • the polyethylene may be not only an ethylene homopolymer but also a copolymer containing a small amount of another ⁇ -olefin.
  • Examples of the ⁇ -olefin include propylene, butene-1, hexene-1, pentene-1, 4-methylpentene-1, octene, vinyl acetate, methyl methacrylate, styrene and the like.
  • the polyolefin multilayer microporous membrane 1 ′ particularly when it is produced by a coextrusion method, it may be difficult to control uneven physical properties in the width direction due to a difference in viscosity between the layers.
  • ultrahigh molecular weight polyethylene the molecular network of the entire membrane is strengthened, so that non-uniform deformation hardly occurs and the multilayer microporous membrane 1 having excellent physical property uniformity can be obtained.
  • the weight average molecular weight (hereinafter referred to as Mw) of the high density polyethylene is preferably 1 ⁇ 10 5 or more, more preferably 2 ⁇ 10 5 or more.
  • the upper limit of the weight average molecular weight of the high density polyethylene is preferably 8 ⁇ 10 5 , more preferably 7 ⁇ 10 5 .
  • the Mw of the ultra high molecular weight polyethylene is preferably 1 ⁇ 10 6 or more and less than 4 ⁇ 10 6 .
  • the Mw of the ultra high molecular weight polyethylene is 4 ⁇ 10 6 or more, the viscosity of the melt becomes too high, and thus there may be a problem in the film forming process such that the resin cannot be extruded from the die. .
  • the content of the ultrahigh molecular weight polyethylene is preferably 5% by mass or more, more preferably 18% by mass or more, with respect to 100% by mass of the entire polyethylene resin constituting the second microporous layer b. .
  • the upper limit of the content of ultrahigh molecular weight polyethylene is preferably 45% by mass or less, more preferably 40% by mass or less, based on 100% by mass of the entire polyethylene resin.
  • the content of the ultrahigh molecular weight polyethylene is within the above preferable range, sufficient tensile strength can be obtained even when the thickness of the polyolefin multilayer microporous membrane 1 ′ is reduced.
  • the tensile strength of the polyolefin multilayer microporous membrane 1 ' is preferably 100 MPa or more. There is no particular upper limit on the tensile strength.
  • the molecular weight distribution (Mw / Mn) which is the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polyolefin resin of the first microporous layer a and the polyethylene resin of the second microporous layer b is respectively It is preferably in the range of 5 to 200, more preferably 10 to 100.
  • Mw / Mn is the above preferable range, it is easy to extrude the polyolefin solution in the production process, and even when the thickness of the polyolefin multilayer microporous membrane 1 'is further reduced, sufficient machinery can be obtained. Strength is obtained.
  • Mw / Mn is used as a measure of molecular weight distribution.
  • Mw / Mn of a single polyolefin resin can be appropriately adjusted by multistage polymerization of polyolefin.
  • Mw / Mn of the mixture of polyolefin resin can be suitably adjusted by adjusting the molecular weight and mixing ratio of each component.
  • the thickness of the polyolefin multilayer microporous membrane 1 ′ is not particularly limited, but the lower limit is 3 ⁇ m or more, more preferably 5 ⁇ m or more, and even more preferably 7 ⁇ m or more. From the viewpoint of increasing the capacity, it is 16 ⁇ m or less, more preferably 12 ⁇ m or less.
  • the film thickness of the polyolefin multilayer microporous membrane 1 ′ is in the above preferred range, practical membrane strength and pore blocking function can be retained, which is more suitable for increasing the capacity of the battery, which is expected to advance in the future.
  • the battery separator 10 of the present embodiment has the polyolefin microporous membrane 1 having a small thickness, the separator 10 between the polyolefin multilayer microporous membrane 1 'and the porous layer 2, and between the separator 10 and the electrode. And when the separator 10 is thinned, the effect is more clearly exhibited.
  • the thickness ratio of the second microporous layer b is preferably 30% or more and 90% or less with respect to the entire layer (the whole) of the polyolefin multilayer microporous membrane 1 ′.
  • the lower limit is more preferably 40% or more, and the upper limit is more preferably 80% or less.
  • an antioxidant In the first microporous layer and the second microporous layer constituting the polyolefin multilayer microporous membrane 1 ′, an antioxidant, a heat stabilizer, an antistatic agent, Various additives such as an ultraviolet absorber, an antiblocking agent, a filler, or a nucleating agent may be contained. In particular, it is preferable to add an antioxidant for the purpose of suppressing oxidative deterioration due to the thermal history of the polyolefin resin. Appropriate selection of the type and amount of antioxidants and heat stabilizers is important for adjusting or enhancing the properties of the polyolefin multilayer microporous membrane 1 '. In addition, in this specification, the addition amount of these additives is not included in content of said 1st polyolefin resin and polyethylene resin.
  • the polyolefin multilayer microporous membrane 1 ′ does not substantially contain inorganic particles.
  • substantially free of inorganic particles means, for example, a content of 50 ppm or less, preferably 10 ppm or less, most preferably the detection limit or less when inorganic elements are quantified by fluorescent X-ray analysis. Even if particles are not positively added to the polyolefin microporous membrane, contaminants derived from foreign substances and raw material resin or dirt attached to the line and equipment in the polyolefin microporous membrane manufacturing process are peeled off. It is because it may be mixed in.
  • the air resistance of this multi-layer, microporous polyolefin membrane 1 ' has an upper limit of 300 sec / 100 cm 3 Air or less, preferably 200 sec / 100 cm 3 Air, more preferably at most 150 sec / 100 cm 3 Air.
  • the upper limit of the porosity of the polyolefin multilayer microporous membrane 1 ′ is preferably 70% or less, more preferably 60% or less, and even more preferably 55% or less.
  • the lower limit of the porosity is preferably 30% or more, more preferably 35% or more, and further preferably 40% or more.
  • the average pore diameter of the polyolefin multilayer microporous membrane 1 ′ greatly affects the pore closing performance, it is preferably 0.01 ⁇ m or more and 1.0 ⁇ m or less, more preferably 0.05 ⁇ m or more and 0.5 ⁇ m or less, and still more preferably 0.8. 1 ⁇ m or more and 0.3 ⁇ m or less.
  • the average pore diameter of the polyolefin multilayer microporous membrane 1 ′ is within the above preferred range, the response to the temperature of the pore clogging phenomenon does not become slow, and the pore clogging temperature due to the temperature rise rate does not shift to a higher temperature side. .
  • the production method of polyolefin multilayer microporous membrane is not particularly limited as long as the polyolefin multilayer microporous membrane 1 'having the above-described properties can be produced, and conventionally known methods can be used. For example, the methods described in the specifications of Japanese Patent No. 2132327 and Japanese Patent No. 3347835, International Publication No. 2006/137540, and the like can be used.
  • the method for producing the polyolefin multilayer microporous membrane 1 ′ preferably includes the following steps (1) to (8).
  • Step (3) of preparing the polyolefin resin solution (3) Steps of coextruding the first and second polyolefin resin solutions to form a sheet and then cooling to obtain an extruded product (4) Stretching the extruded product (first (1) stretching step) to obtain a gel-like multilayer sheet (5) removing the film-forming solvent from the gel-like multilayer sheet and obtaining the multilayer sheet (6) drying the multilayer sheet, Step of obtaining (7) Step of drawing the first stretched multilayer sheet to obtain a second stretched multilayer sheet (8) Step of heat treating the second stretched multilayer sheet to obtain a polyolef
  • the first and second polyolefin resin solutions are simultaneously extruded by a multilayer die under a specific condition to form a multilayer sheet. .
  • the first and second polyolefin resin solutions are simultaneously extruded by a multilayer die under a specific condition to form a multilayer sheet. .
  • meltdown temperature mechanical strength, air permeability resistance and porosity, and a polyolefin multi-layer microporous membrane having a small maximum pore diameter. 1 can be manufactured. These characteristics cannot be achieved by the single-layer polyolefin microporous membrane 1.
  • the step (1) and the step (2) after using the above-described resin material, in the step (4) and the step (7), the film is stretched under an appropriate temperature condition to be described later. Good porosity and fine pore structure control can be achieved.
  • an appropriate film-forming solvent is added to the first polyolefin resin and polyethylene resin, respectively, and then melt-kneaded.
  • First and second polyolefin resin solutions are prepared, respectively.
  • a melt-kneading method for example, a method using a twin-screw extruder described in the specifications of Japanese Patent No. 2132327 and Japanese Patent No. 3347835 can be used. Since the melt-kneading method is well-known, description is abbreviate
  • the mixing ratio of the first or second polyolefin resin and the film-forming solvent in the first or second polyolefin resin solution is not particularly limited, but is 20 to 30 parts by mass of the first or second polyolefin resin.
  • the film forming solvent is preferably 70 to 80 parts by mass.
  • Step (3) Extrusion Forming Step Next, the first and second polyolefin resin solutions are respectively fed from an extruder to one die, where the two solutions are combined in layers and extruded into a sheet.
  • the extrusion method may be either a flat die method or an inflation method. In either method, the solution is supplied to separate manifolds and stacked in layers at the lip inlet of a multilayer die (multiple manifold method), or the solution is supplied to the die in a layered flow in advance (block method) ) Can be used. Since the multi-manifold method and the block method itself are known, a detailed description thereof will be omitted.
  • the gap of the multi-layer flat die is 0.1 to 5 mm.
  • the extrusion temperature is preferably 140 to 250 ° C., and the extrusion speed is preferably 0.2 to 15 m / min.
  • an extruded molded body is formed by cooling the obtained laminated extruded molded body.
  • a forming method of the formed body for example, methods disclosed in Japanese Patent No. 2132327 and Japanese Patent No. 3347835 can be used. Cooling is preferably performed at a rate of 50 ° C./min or more at least up to the gelation temperature. Cooling is preferably performed to 30 ° C. or lower.
  • the microphases of the first and second polyolefins separated by the film-forming solvent can be fixed. When the cooling rate is within the above range, the crystallinity is maintained in an appropriate range, and an extruded product suitable for stretching is obtained.
  • a method of contacting with a cooling medium such as cold air or cooling water, a method of contacting with a cooling roll, or the like can be used, but it is preferable that the cooling is performed by contacting with a roll cooled with a cooling medium.
  • Step (4) First Stretching Step Next, the obtained extruded molded body is stretched at least in a uniaxial direction (first stretching) to obtain a gel-like multilayer sheet. Since the extruded product contains a film-forming solvent, it can be stretched uniformly.
  • the extruded body is preferably stretched at a predetermined ratio after heating by a tenter method, a roll method, an inflation method, or a combination thereof.
  • the stretching may be uniaxial stretching or biaxial stretching, but biaxial stretching is preferred. In the case of biaxial stretching, any of simultaneous biaxial stretching, sequential stretching and multistage stretching (for example, a combination of simultaneous biaxial stretching and sequential stretching) may be used.
  • the stretching ratio (area stretching ratio) in this step is preferably 2 times or more, and more preferably 3 times or more and 30 times or less.
  • 9 times or more is preferable, 16 times or more is more preferable, and 25 times or more is particularly preferable.
  • it is preferably 3 times or more in both the longitudinal direction and the transverse direction (MD and TD directions), and the draw ratios in the MD direction and the TD direction may be the same or different.
  • the draw ratio in this process means the area draw ratio of the microporous film immediately before being used for the next process on the basis of the microporous film immediately before this process.
  • the stretching temperature is preferably 90 ° C. or higher and 130 ° C. or lower, more preferably 110 ° C. or higher and 120 ° C. or lower, and still more preferably 114 ° C. or higher and 117 ° C. or lower.
  • the film may be stretched by providing a temperature distribution in the film thickness direction, whereby a multilayer microporous film having further excellent mechanical strength can be obtained. Details of the method are described in Japanese Patent No. 3347854.
  • the film-forming solvent is removed from the gel-like multilayer sheet to obtain a multilayer sheet. Removal (cleaning) of the film-forming solvent is performed using a cleaning solvent.
  • the first and second polyolefin phases are phase-separated from the film-forming solvent phase. Therefore, when the film-forming solvent is removed, a porous film is obtained.
  • the obtained porous film is composed of fibrils forming a fine three-dimensional network structure, and has pores (voids) that communicate irregularly three-dimensionally. Since the cleaning solvent and the method for removing the film-forming solvent using the same are known, the description thereof is omitted. For example, the methods disclosed in Japanese Patent No. 2132327 and Japanese Patent Application Laid-Open No. 2002-256099 can be used.
  • Step (6) Drying Next, the multilayer sheet is dried to obtain a first stretched multilayer sheet. Drying is preferably carried out until the residual cleaning solvent is 5% by mass or less, more preferably 3% by mass or less, with the multilayer microporous membrane being 100% by mass (dry weight). When the residual cleaning solvent is within the above range, the porosity of the multilayer microporous membrane is maintained when the second stretching step and heat treatment step described below are performed, and deterioration of permeability is suppressed.
  • the drying temperature is preferably 50 ° C. or higher and 80 ° C. or lower.
  • the first stretched multilayer sheet after drying is preferably stretched in at least a uniaxial direction.
  • the first stretched multilayer sheet can be stretched by the tenter method or the like while heating.
  • the stretching may be uniaxial stretching or biaxial stretching. In the case of biaxial stretching, either simultaneous biaxial stretching or sequential stretching may be used.
  • the stretching temperature in this step is not particularly limited, but is usually 90 to 135 ° C, more preferably 95 to 130 ° C.
  • the lower limit of the stretching ratio (area stretching ratio) in the uniaxial direction of stretching of the first stretched multilayer sheet in this step is preferably 1.0 times or more, more preferably 1.1 times or more, and further preferably 1 .2 times or more.
  • the upper limit is preferably 1.8 times or less.
  • the lower limit of the area stretching ratio is preferably 1.0 times or more, more preferably 1.1 times or more, and still more preferably 1.2 times or more.
  • the upper limit is preferably 3.5 times or less, and 1.0 to 2.0 times in each of the MD direction and the TD direction, and the draw ratios in the MD direction and the TD direction may be the same or different.
  • the draw ratio in this process means the draw ratio of the 2nd extending
  • the heat treatment method heat setting treatment and / or heat relaxation treatment can be used.
  • the heat setting treatment is a heat treatment in which heating is performed while keeping the dimensions of the film unchanged.
  • the thermal relaxation treatment is a heat treatment that heat-shrinks the film in the MD direction or the TD direction during heating.
  • the heat setting treatment is preferably performed by a tenter method or a roll method.
  • a thermal relaxation treatment method a method disclosed in Japanese Patent Application Laid-Open No. 2002-256099 can be given.
  • the heat treatment temperature is more preferably within the range of ⁇ 5 ° C. of the second stretching temperature of the second stretched multilayer sheet, and particularly preferably within the range of ⁇ 3 ° C.
  • Porous layer The porous layer 2 contains two types of vinylidene fluoride-hexafluoropropylene copolymers (VdF-HFP) and inorganic particles. Hereinafter, each component which comprises the porous layer 2 is demonstrated below.
  • VdF-HFP vinylidene fluoride-hexafluoropropylene copolymers
  • the vinylidene fluoride-hexafluoropropylene copolymer (A) (hereinafter sometimes simply referred to as copolymer (A)) is a copolymer containing vinylidene fluoride units and hexafluoropropylene units. As described later, it contains a hydrophilic group.
  • the lower limit of the content of hexafluoropropylene units in the copolymer (A) is 0.3 mol%, preferably 0.5 mol%.
  • the upper limit of the content of hexafluoropropylene units is 5.0 mol%, more preferably 2.5 mol%.
  • the lower limit of the weight average molecular weight of the copolymer (A) is 900,000, preferably 1,000,000.
  • the upper limit of the weight average molecular weight of the copolymer (A) is 2 million, more preferably 1.5 million.
  • the weight average molecular weight of the copolymer (A) is within the above range, in the step of forming the porous layer, the time for dissolving the copolymer (A) in the solvent is not extremely long, and the production efficiency is increased. Can maintain an appropriate gel strength when swollen in the electrolyte, and can improve the bending strength when wet.
  • the weight average molecular weight of a copolymer (A) is a polystyrene conversion value by a gel permeation chromatography.
  • the copolymer (A) has a hydrophilic group. Since the copolymer (A) has a hydrophilic group, the copolymer (A) can be more firmly bonded to the active material existing on the electrode surface and the binder component in the electrode. The reason for this is not particularly limited, but it is presumed that the adhesive force is improved by hydrogen bonding.
  • the hydrophilic group include a hydroxyl group, a carboxylic acid group, a sulfonic acid group, and salts thereof. Among these, carboxylic acid groups and carboxylic acid esters are particularly preferable.
  • a method for introducing a hydrophilic group into the copolymer (A) a known method can be used.
  • maleic anhydride, maleic acid, maleic ester, malein A method of introducing a monomer having a hydrophilic group such as acid monomethyl ester into the main chain by copolymerization or a method of introducing it as a side chain by grafting can be used.
  • the hydrophilic group modification rate can be measured by FT-IR, NMR, quantitative titration or the like.
  • a carboxylic acid group it can be determined from the absorption intensity ratio of C—H stretching vibration and C ⁇ O stretching vibration of a carboxyl group based on a homopolymer using FT-IR.
  • the lower limit of the hydrophilic group content of the copolymer (A) is preferably 0.1 mol%, more preferably 0.3 mol%.
  • the upper limit of the hydrophilic group content is preferably 5.0 mol%, more preferably 4.0 mol%.
  • the content of the hydrophilic group exceeds 5.0 mol%, the polymer crystallinity becomes too low, the degree of swelling with respect to the electrolytic solution becomes high, and the bending strength when wet is deteriorated.
  • the content of the hydrophilic group is within the above range, the affinity between the inorganic particles contained in the porous layer 2 and the copolymer (A) is increased, the short circuit resistance is improved, and the inorganic particles are removed.
  • strength of the porous layer 2 increases with the copolymer (A) which has a hydrophilic group which is the main component of the porous layer 2, and an inorganic particle.
  • the quantification of the hydrophilic group of the vinylidene fluoride-hexafluoropropylene copolymer in the porous layer 2 can be determined by IR (infrared absorption spectrum) method, NMR (nuclear magnetic resonance) method or the like.
  • the copolymer (A) is a copolymer obtained by further polymerizing other monomers other than vinylidene fluoride, hexafluoropropylene, and a monomer having a hydrophilic group, as long as the characteristics are not impaired. Also good.
  • other monomers include monomers such as tetrafluoroethylene, trifluoroethylene, trichloroethylene, and vinyl fluoride.
  • the separator 10 has a high affinity for the nonaqueous electrolyte when used in a nonaqueous electrolyte secondary battery, and is chemically and physically Stability is high, it exhibits bending strength when wet, and the affinity with the electrolyte is sufficiently maintained even when used at high temperatures.
  • the vinylidene fluoride-hexafluoropropylene copolymer (B) (hereinafter sometimes simply referred to as copolymer (B)) is a copolymer containing vinylidene fluoride units and hexafluoropropylene units. .
  • the content of hexafluoropropylene in the copolymer (B) exceeds 5.0 mol%, more preferably 6.0 mol% or more, and even more preferably 7.0 mol% or more.
  • the content of the hexafluoropropylene unit is 5.0 mol% or less, the adhesion between the separator and the electrode during drying (peeling force during drying) may not be sufficiently obtained.
  • the upper limit is 8.0 mol%, more preferably 7.5 mol%.
  • the content of the hexafluoropropylene unit exceeds 8.0 mol%, it may swell excessively with respect to the electrolytic solution, and the bending strength when wet may decrease.
  • the copolymer (B) may contain a hydrophilic group or not.
  • the copolymer (B) has a weight average molecular weight of 100,000 to 750,000.
  • weight average molecular weight of the copolymer (B) is in the above range, it has high affinity for the non-aqueous electrolyte, high chemical and physical stability, and excellent separator and electrode during drying. Adhesiveness (peeling force when dried) is obtained.
  • the reason for this is not particularly limited, but the copolymer (B) has fluidity under heating and pressure conditions that develop a peeling force during drying, and becomes an anchor by entering the porous layer of the electrode. It can be presumed that the layer 2 and the electrode have strong adhesiveness.
  • the copolymer (B) contributes to the peeling force at the time of drying, and can contribute to the deflection of the wound electrode body and the laminated electrode body, the prevention of distortion, and the improvement of the transportability.
  • the copolymer (B) is a resin different from the copolymer (A).
  • the lower limit of the weight average molecular weight of the copolymer (B) is 100,000, preferably 150,000.
  • the weight average molecular weight of the copolymer (B) is below the lower limit of the above range, the amount of entanglement of the molecular chains is too small, so that the resin strength becomes weak and the porous layer 2 is liable to cohesive failure.
  • the upper limit of the weight average molecular weight of the copolymer (B) is preferably 750,000, more preferably 700,000. When the weight average molecular weight of a copolymer (B) exceeds the upper limit of the said range, in order to obtain the peeling force at the time of drying, it is necessary to raise the press temperature in the manufacturing process of a winding body.
  • the lower limit of the melting point of the copolymer (B) is preferably 60 ° C, more preferably 80 ° C.
  • the upper limit of the melting point of the copolymer (B) is preferably 145 ° C, more preferably 140 ° C.
  • fusing point (Tm) is the temperature of the peak top of the endothermic peak at the time of temperature rising measured by the differential scanning calorimetry (DSC) method.
  • the copolymer (B) is a copolymer having a vinylidene fluoride unit and a hexafluoropropylene unit.
  • the copolymer (B) can be obtained by a suspension polymerization method or the like, similar to the copolymer (A).
  • the melting point of the copolymer (B) can be adjusted by controlling the crystallinity of the site composed of vinylidene fluoride units. For example, when the copolymer (B) contains a monomer other than the vinylidene fluoride unit, the melting point can be adjusted by controlling the ratio of the vinylidene fluoride unit.
  • Monomers other than vinylidene fluoride units are tetrafluoroethylene, trifluoroethylene, trichloroethylene, hexafluoropropylene, fluorinated vinyl maleic anhydride, maleic acid, maleic acid ester, maleic acid monomethyl ester, etc. You may have more. Examples thereof include a method in which the monomer is added when the copolymer (B) is polymerized and introduced into the main chain by copolymerization, or a method in which it is introduced as a side chain by grafting. Further, the melting point may be adjusted by controlling the ratio of Head-to-Head bonds (—CH 2 —CF 2 —CF 2 —CH 2 —) of vinylidene fluoride units.
  • the content of the copolymer (A) is 86% by mass, more preferably 88% by mass, with respect to 100% by mass of the total weight of the copolymer (A) and the copolymer (B). is there.
  • the upper limit of the content of the copolymer (A) is 98% by mass, more preferably 97% by mass.
  • the upper limit of the content of the copolymer (B) is 14% by mass, preferably 12% by mass with respect to 100% by mass of the total weight of the copolymer (A) and the copolymer (B). It is.
  • the lower limit of the content of the copolymer (B) is 2% by mass, which is 3% by mass.
  • the porous layer 2 can contain a resin other than the copolymer (A) and the copolymer (B) as long as the effects of the present invention are not impaired.
  • the copolymer (A) and the copolymer (B) are preferably used.
  • content of the said copolymer (A) or the said copolymer (B) is 100 mass of resin components of the porous layer 2. % As a percentage.
  • the porous layer 2 contains inorganic particles. By including particles in the porous layer 2, the short-circuit resistance can be particularly improved, and an improvement in thermal stability can be expected.
  • Inorganic particles include calcium carbonate, calcium phosphate, amorphous silica, crystalline glass particles, kaolin, talc, titanium dioxide, alumina, silica-alumina composite oxide particles, barium sulfate, calcium fluoride, lithium fluoride, zeolite , Molybdenum sulfide, mica, boehmite, magnesium oxide and the like.
  • inorganic particles containing a large amount of OH groups are preferred, and specifically, selected from titanium dioxide, alumina, and boehmite. It is preferable to use more than one type.
  • the content of the inorganic particles contained in the porous layer 2 is 80% by volume, preferably 70% by volume, more preferably 60% by volume with respect to 100% by volume of the solid content volume of the porous layer 2. It is. On the other hand, the lower limit of the content of inorganic particles is 40% by volume, more preferably 45% by volume, still more preferably 50% by volume, and most preferably 51% by volume.
  • the content of the inorganic particles contained in the porous layer 2 was calculated by calculating the density of the copolymer (A) and the copolymer (B) as 1.77 g / cm 3 .
  • the porous layer 2 when inorganic particles having no adhesiveness are contained in the porous layer, the bending strength when wet and the peeling force when drying tend to decrease.
  • the porous layer 2 according to the present embodiment contains a specific fluororesin in a specific ratio, so that when the inorganic particles are contained in the above range, the porous layer 2 has a high adhesive force to the electrode, The balance between the bending strength when wet and the peeling force when drying is good, and excellent short-circuit resistance can be obtained.
  • the average particle size of the inorganic particles is preferably 1.5 times or more and 50 times or less, more preferably 2.0 times or more and 20 times or less of the average flow pore size of the polyolefin microporous membrane. It is.
  • the average flow pore size was measured according to JISK3832 and ASTM F316-86, and for example, measured in the order of Dry-up and Wet-up using a palm porometer (PMI, CFP-1500A).
  • PMI palm porometer
  • pressure was applied to a microporous membrane sufficiently immersed in Galwick (trade name) manufactured by PMI with a known surface tension, and the pore size converted from the pressure at which air began to penetrate was defined as the maximum pore size.
  • d C ⁇ ⁇ / P
  • d ( ⁇ m) is the pore diameter of the microporous membrane
  • ⁇ (mN / m) is the surface tension of the liquid
  • P (Pa) is the pressure
  • C is a constant.
  • the average particle size of the inorganic particles is preferably 0.3 ⁇ m to 1.8 ⁇ m, more preferably 0.5 ⁇ m to 1.5 ⁇ m, still more preferably. 0.9 ⁇ m to 1.3 ⁇ m.
  • the average particle diameter of the particles can be measured using a laser diffraction method or dynamic light scattering method measuring device. For example, particles dispersed in an aqueous solution containing a surfactant using an ultrasonic probe were measured with a particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd., Microtrac HRA) and accumulated 50% from the small particle side in terms of volume.
  • the value of the particle size (D50) at the time is preferably the average particle size.
  • Examples of the shape of the particles include a true spherical shape, a substantially spherical shape, a plate shape, and a needle shape, but are not particularly limited.
  • the film thickness of the porous layer 2 is preferably 0.5 ⁇ m or more and 3 ⁇ m or less per side, more preferably 1 ⁇ m or more and 2.5 ⁇ m or less, and further preferably 1 ⁇ m or more and 2 ⁇ m or less.
  • the film thickness per side is 0.5 ⁇ m or more, high adhesion to the electrode (bending strength when wet, peel strength when drying) can be secured.
  • the film thickness per side is 3 ⁇ m or less, the winding volume can be suppressed and the film can be made thinner, which is more suitable for increasing the capacity of batteries that will be developed in the future.
  • the porosity of the porous layer 2 is preferably 30% or more and 90% or less, more preferably 40% or more and 70% or less. When the porosity of the porous layer 2 is within the above range, an increase in the electrical resistance of the separator can be prevented, a large current can be passed, and the film strength can be maintained.
  • the manufacturing method of the battery separator is not particularly limited, and can be manufactured using a known method. Hereinafter, an example of a method for manufacturing a battery separator will be described.
  • the battery separator manufacturing method can include the following steps (1) to (3) in sequence. (1) A step of obtaining a fluororesin solution in which a vinylidene fluoride-hexafluoropropylene copolymer (A) and a vinylidene fluoride-hexafluoropropylene copolymer (B) are dissolved in a solvent. (2) Inorganic in the fluororesin solution. A step of adding particles, mixing and dispersing to obtain a coating solution (3) A step of applying the coating solution to the polyolefin microporous membrane, immersing it in a coagulation solution, washing and drying.
  • Step (1) Step of obtaining a fluororesin solution
  • the vinylidene fluoride-hexafluoropropylene copolymer (A) and the vinylidene fluoride-hexafluoropropylene copolymer (B) are gradually added to a solvent and completely dissolved.
  • the solvent is not particularly limited as long as it can dissolve the vinylidene fluoride-hexafluoropropylene copolymer (A) and the vinylidene fluoride-hexafluoropropylene copolymer (B) and is miscible with the coagulation liquid.
  • the solvent is preferably N-methyl-2-pyrrolidone.
  • Step (2) Step of obtaining a coating solution
  • a coating solution it is important to sufficiently disperse inorganic particles. Specifically, particles are added while stirring the fluororesin solution and pre-dispersed by stirring with a disper for a certain time (for example, about 1 hour), and then dispersed using a bead mill or paint shaker. Through the step (dispersing step), the aggregation of particles is reduced, and further mixed with a three-one motor with a stirring blade to prepare a coating solution.
  • Step (3) A step of applying the coating liquid to the microporous film, immersing it in the coagulating liquid, washing and drying, applying the coating liquid to the microporous film, immersing the applied microporous film in the coagulating liquid
  • the vinylidene fluoride-hexafluoropropylene copolymer (A) and the vinylidene fluoride-hexafluoropropylene copolymer (B) are phase-separated, coagulated in a state having a three-dimensional network structure, washed and dried.
  • a microporous membrane and a battery separator having a porous layer on the surface of the microporous membrane are obtained.
  • the method of applying the coating liquid to the microporous film may be a known method, for example, dip coating method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, Examples thereof include an air knife coating method, a Mayer bar coating method, a pipe doctor method, a blade coating method, and a die coating method, and these methods can be used alone or in combination.
  • the coagulation liquid preferably contains water as a main component, and is preferably an aqueous solution containing 1 to 20% by mass of a good solvent for the copolymer (A) and the copolymer (B), more preferably 5 to 15% by mass. It is an aqueous solution.
  • a good solvent include N-methyl-2-pyrrolidone, N, N-dimethylformamide, and N, N-dimethylacetamide.
  • the immersion time in the coagulation liquid is preferably 3 seconds or more. The upper limit is not limited, but 10 seconds is sufficient.
  • Water can be used for cleaning. Drying can be performed using, for example, hot air of 100 ° C. or less.
  • the battery separator 10 of the present embodiment can be suitably used for both a battery using an aqueous electrolyte and a battery using a non-aqueous electrolyte, but is preferably used for a non-aqueous electrolyte secondary battery. It can. Specifically, it can be preferably used as a separator for secondary batteries such as nickel-hydrogen batteries, nickel-cadmium batteries, nickel-zinc batteries, silver-zinc batteries, lithium secondary batteries, and lithium polymer secondary batteries. Especially, it is preferable to use as a separator of a lithium ion secondary battery.
  • a positive electrode and a negative electrode are arranged via a separator, and the separator contains an electrolytic solution (electrolyte).
  • the structure of the non-aqueous electrolyte electrode is not particularly limited, and a conventionally known structure can be used.
  • an electrode structure coin type in which a disk-like positive electrode and a negative electrode are opposed to each other, a flat plate-like structure
  • An electrode structure stacked type in which positive and negative electrodes are alternately stacked, an electrode structure in which stacked belt-like positive and negative electrodes are wound (winding type), and the like can be used.
  • the battery separator of this embodiment can have excellent adhesiveness between the separator and the electrode in any battery structure.
  • the current collector, the positive electrode, the positive electrode active material, the negative electrode, the negative electrode active material, and the electrolyte used in the non-aqueous electrolyte secondary battery including a lithium ion secondary battery are not particularly limited, and a conventionally known material is appropriately selected. They can be used in combination.
  • the battery separator 10 may be formed by laminating the porous 2 on one surface of the polyolefin microporous membrane 1, and porous on both surfaces of the polyolefin microporous membrane 1. 2 may be laminated.
  • the wet bending strength of the separator 10 is preferably 4.0 N or more, more preferably 5.0 N or more, and still more preferably 6.0 N or more.
  • the upper limit of the bending strength when wet is not particularly defined, but is, for example, 15.0 N or less.
  • the bending strength when wet can be measured by the method described in Examples described later.
  • the peeling force when the separator 10 is dried is preferably 2.0 N / m or more, more preferably 5.0 N / m or more, and still more preferably 6.0 N / m or more.
  • the upper limit of the peeling force at the time of drying is not particularly defined, it is, for example, 40.0 N / m or less.
  • the peeling force at the time of drying is within the preferable range, it is expected that the wound electrode body or the laminated electrode body can be transported without the electrode body being scattered.
  • the peeling force at the time of drying can be measured by the method as described in the below-mentioned Example.
  • the separator 10 of the present embodiment can achieve both a high bending strength when wet and a high peel strength when drying. Specifically, the separator 10 can satisfy a bending strength when wet of 4.0 N or more and a peel strength when dry of 2.0 N / m or more, as shown in Examples described later.
  • a preferable upper limit of the air resistance of the separator 10 is 350 sec / 100 cm 3 Air, preferably 250 sec / 100 cm 3 Air, and more preferably 200 sec / 100 cm 3 Air.
  • the lower limit is 50 sec / 100 cm 3 Air, preferably 70 sec / 100 cm 3 Air, more preferably 100 sec / 100 cm 3 Air.
  • this invention is not limited to said embodiment, It can implement in various deformation
  • film thickness Using a contact-type film thickness meter (“Lightmatic” (registered trademark) series 318 manufactured by Mitutoyo Corporation), the film thicknesses of the microporous film and the separator were measured. In the measurement, 20 points were measured under the condition of a weight of 0.01 N using a carbide spherical measuring element ⁇ 9.5 mm, and the average value of the obtained measured values was taken as the film thickness.
  • Lightmatic registered trademark
  • Weight average molecular weight (Mw) of vinylidene fluoride-hexafluoropropylene copolymer (A) and vinylidene fluoride-hexafluoropropylene copolymer (B) It calculated
  • Measurement device GPC-150C manufactured by Waters Corporation ⁇ Column: 2 shodex KF-806M manufactured by Showa Denko KK ⁇ Column temperature: 23 ° C Solvent (mobile phase): 0.05M lithium chloride added N-methyl-2-pyrrolidone (NMP) ⁇ Solvent flow rate: 0.5 ml / min ⁇ Sample preparation: 4 mL of measurement solvent was added to 2 mg of the sample, and gently stirred at room temperature (dissolution was visually confirmed).
  • ⁇ Injection volume 0.2mL
  • ⁇ Detector Differential refractive index detector RI (RI-8020 type sensitivity 16 manufactured by Tosoh Corporation)
  • -Calibration curve Prepared from a calibration curve obtained using a monodisperse polystyrene standard sample, using a predetermined conversion constant.
  • the negative electrode 20 (machine direction 161 mm ⁇ width direction 30 mm) produced above and the produced separator 10 (machine direction 160 mm ⁇ width direction 34 mm) are stacked, and a metal plate (length 300 mm, width 25 mm, thickness 1 mm) is laminated.
  • the separator 10 and the negative electrode 20 were wound so that the separator 10 was inside as a winding core, and the metal plate was pulled out to obtain a test winding body 30.
  • the test winding was about 34 mm long and about 28 mm wide.
  • test roll 30 enclosed in the laminate film 22 is sandwiched between two gaskets (thickness 1 mm, 5 cm ⁇ 5 cm), and placed in a precision heating and pressing apparatus (CYPT-10, manufactured by Shinto Kogyo Co., Ltd.). The mixture was pressurized at 98 ° C. and 0.6 MPa for 2 minutes and allowed to cool at room temperature. With the test roll 30 after being pressurized, the bending strength when wet was measured using a universal testing machine (manufactured by Shimadzu Corporation, AGS-J) while encapsulated in the laminate film 22. Details will be described below with reference to FIG.
  • Two aluminum L-shaped angles 41 are arranged in parallel so that the 90 ° part is on top, with the ends aligned, and the fulcrum with the 90 ° part as a fulcrum The distance was fixed to 15 mm.
  • the length direction of the L-shaped angle 41 by aligning the midpoint of the width direction of the test winding body (about 28 mm) with the 7.5 mm point which is the middle of the distance between the fulcrums of the two aluminum L-shaped angles 41
  • the test winding body 30 was arranged so as not to protrude from the sides of the test piece.
  • the length direction side (about 34 mm) of the test winding body does not protrude from the length direction side of the aluminum L-shaped angle 42 (thickness 1 mm, 10 mm ⁇ 10 mm, length 4 cm) as an indenter.
  • the 90 ° portion of the aluminum L-shaped angle 42 is aligned with the midpoint of the side in the width direction of the test winding body, and the aluminum L-shaped angle 42 is placed so that the 90 ° portion is down. It was fixed to the load cell (load cell capacity 50N) of the universal testing machine.
  • the average value of the maximum test force obtained by measuring the three test winding bodies at a load speed of 0.5 mm / min was defined as the bending strength when wet.
  • a double-sided tape having a width of 1 cm is attached to the negative electrode side of the laminate of the negative electrode 20 and the separator 10, and the other side of the double-sided tape is attached to a SUS plate (thickness 3 mm, length 150 mm ⁇ width 50 mm). The pasting was performed so that the machine direction and the SUS plate length direction were parallel. This was made into the peeling test piece.
  • a separator 10 was sandwiched between load cell side chucks using a universal testing machine (AGS-J, manufactured by Shimadzu Corporation), and a 180 degree peel test was performed at a test speed of 300 mm / min.
  • a value obtained by averaging measured values from a stroke of 20 mm to 70 mm during the peel test was defined as the peel strength of the peel test piece.
  • a total of three peel test pieces were measured, and a value obtained by converting the average peel force into a width was defined as a peel force during drying (N / m).
  • the sample laminate 31 was fixed to the compression jig (lower side) 44 of the universal testing machine with double-sided tape.
  • the aluminum foil 4 and the negative electrode 21 of the sample laminate 31 were connected to a circuit composed of a capacitor and a clad resistor with a cable.
  • the capacitor was charged to about 1.5 V, and a metal ball 6 (material: chromium (SUJ-2)) having a diameter of about 500 ⁇ m was placed between the separator in the sample laminate 31 and the aluminum foil 4.
  • a compression jig is attached to the universal testing machine, and the sample laminate 31 including the metal balls 6 is placed between both compression jigs 43 and 44 as shown in FIG. / Min. The test was terminated when the load reached 100 N.
  • the part where the inflection point appeared in the change in compressive load was taken as the film breaking point of the separator, and the moment when the circuit was formed and the current was detected via the metal sphere was taken as the short-circuit occurrence point.
  • the compression displacement A (t) when the separator breaks due to compression and an inflection point occurs in the compression stress, and the compression displacement B (t) at the moment when the current flows through the circuit are measured. If the numerical value obtained in 1.1 is 1.1 or more, even if the separator breaks due to foreign matter mixed in the battery, it means that the insulation is maintained by the coating layer composition adhering to the surface of the foreign matter, Short-circuit resistance was evaluated as good.
  • Peel strength between the porous layer and polyolefin multilayer microporous membrane (tape peel strength) (Preparation of peel test piece)
  • the separators (machine direction: 120 mm ⁇ width direction: 25 mm) prepared in Examples and Comparative Examples were installed on a glass plate so that air did not enter.
  • Double-sided tape (machine direction 100mm x width direction 20mm, manufactured by Seiwa Sangyo Co., Ltd., transparent film double-sided tape SFR-2020) is installed so that the machine direction of the separator and the machine direction of the separator are aligned.
  • the sample was subjected to 5 reciprocating treatments using a roller (SA-1003-B, tester industry, manual type, rubber strength 80 ⁇ 5 Hs).
  • a cellophane tape (manufactured by Nichiban Co., Ltd., cello tape (registered trademark), plant-based, No. 405, machine direction: 100 mm ⁇ width direction: 15 mm) is pasted on the separator side of the laminate of the double-sided tape and the separator, and the rest is left.
  • the porous layer surface may remain on the polyolefin multilayer microporous membrane side at the peeling interface.
  • the peel strength between the porous layer and the polyolefin multilayer microporous membrane was calculated.
  • the peel strength between the porous layer and the polyolefin multilayer microporous membrane is preferably 0.15 N / mm or more, more preferably 0.20 N / mm or more, and most preferably 0.25 N / mm or more.
  • Example 1 Preparation of First Polyolefin Resin Solution 20% by mass of polypropylene (PP: melting point 162 ° C.) having a Mw of 2.0 ⁇ 10 6 and high density polyethylene (HDPE: density of 0.6) having an Mw of 5.6 ⁇ 10 5 .
  • PP polypropylene
  • HDPE high density polyethylene
  • a mixture was prepared by blending 0.2 part by mass of methane.
  • Second polyolefin resin solution 40% by mass of ultra high molecular weight polyethylene (UHMwPE) having Mw of 2.0 ⁇ 10 6 and high density polyethylene (HDPE: density of 0.955 g) having Mw of 5.6 ⁇ 10 5 / Cm 3 ) 100 parts by mass of a second polyolefin resin composed of 60% by mass with 0.2 parts by mass of the antioxidant tetrakis [methylene-3- (3,5-ditertiarybutyl-4-hydroxyphenyl) -propionate] methane Parts were blended to prepare a mixture.
  • UHMwPE ultra high molecular weight polyethylene
  • HDPE high density polyethylene
  • the first and second polyolefin resin solutions are supplied from each twin-screw extruder to the three-layer T-die, and the first polyolefin resin solution / second polyolefin resin solution / first polyolefin resin solution.
  • the film was extruded so as to have a layer thickness ratio of 10/80/10, and cooled while being drawn at a take-up speed of 2 m / min with a cooling roll adjusted to 30 ° C. to obtain a three-layer extrudate.
  • Second stretching and heat setting The first stretched multilayer sheet was stretched 1.4 times (second stretching) in the TD direction at 126 ° C using a batch stretching machine. Next, this membrane was heat-set at 126 ° C. by a tenter method to obtain a polyolefin three-layer microporous membrane A having a thickness of 12 ⁇ m, a porosity of 46%, and an air resistance of 150 seconds / 100 cc.
  • copolymer (A1) was synthesized as follows. The molar ratio of vinylidene fluoride / hexafluoropropylene / maleic acid monomethyl ester was 98.0 / 1.5 / 0.5 by suspension polymerization using vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester as starting materials. Thus, a copolymer (A1) was synthesized. The weight average molecular weight of the obtained copolymer (A1) was 1,500,000.
  • copolymer (B1) was synthesized as follows. A copolymer (B1) was synthesized by suspension polymerization using vinylidene fluoride and hexafluoropropylene as starting materials so that the molar ratio of vinylidene fluoride / hexafluoropropylene was 93.0 / 7.0. The weight average molecular weight of the obtained copolymer (B1) was 300,000.
  • the obtained coating liquid (A) was applied to both sides of the polyolefin three-layer microporous membrane A in an equal amount by a dip coating method.
  • the coated film is immersed in an aqueous solution (coagulation solution) containing 10% by mass of N-methyl-2-pyrrolidone (NMP), washed with pure water, and then dried at 50 ° C. to obtain a battery separator. It was.
  • the thickness of the battery separator was 15 ⁇ m.
  • Example 2 In the preparation of the first polyolefin resin solution, the thickness was 12 ⁇ m, the porosity was 45%, in the same manner as in Example 1 except that the blending amount of polypropylene was 10% by mass and the blending amount of high-density polyethylene was 90% by mass.
  • a battery separator was obtained in the same manner as in Example 1 except that the polyolefin three-layer microporous membrane B was used.
  • Example 3 In the preparation of the first polyolefin resin solution, the thickness was 12 ⁇ m, the porosity was 48%, in the same manner as in Example 1 except that the blending amount of polypropylene was 45 mass% and the blending amount of high-density polyethylene was 55 mass%.
  • a battery separator was obtained in the same manner as in Example 1 except that the polyolefin three-layer microporous membrane C was used.
  • copolymer (B2) was synthesized as follows.
  • a copolymer (B2) was synthesized by suspension polymerization using vinylidene fluoride and hexafluoropropylene as starting materials so that the molar ratio of vinylidene fluoride / hexafluoropropylene was 94.5 / 5.5.
  • the weight average molecular weight of the obtained copolymer (B2) was 280,000.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (B) in which the copolymer (B1) was replaced with the copolymer (B2) was used in the preparation of the coating liquid.
  • Example 5 As the copolymer (B), a copolymer (B3) was synthesized as follows. A copolymer (B3) was synthesized by suspension polymerization using vinylidene fluoride and hexafluoropropylene as starting materials so that the molar ratio of vinylidene fluoride / hexafluoropropylene was 92.0 / 8.0. The weight average molecular weight of the obtained copolymer (B3) was 350,000. A battery separator was obtained in the same manner as in Example 1 except that the coating liquid (C) in which the copolymer (B1) was replaced with the copolymer (B3) was used in the preparation of the coating liquid.
  • the coating liquid (C) in which the copolymer (B1) was replaced with the copolymer (B3) was used in the preparation of the coating liquid.
  • copolymer (A2) was synthesized as follows. The molar ratio of vinylidene fluoride / hexafluoropropylene / maleic acid monomethyl ester was 99.0 / 0.5 / 0.5 by suspension polymerization using vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester as starting materials. Thus, a copolymer (A2) was synthesized. The weight average molecular weight of the obtained copolymer (A2) was 1,400,000.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (D) in which the copolymer (A1) was replaced with the copolymer (A2) was used in the preparation of the coating liquid.
  • copolymer (A3) was synthesized as follows. The molar ratio of vinylidene fluoride / hexafluoropropylene / maleic acid monomethyl ester was 95.0 / 4.5 / 0.5 by suspension polymerization using vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester as starting materials. Thus, a copolymer (A3) was synthesized. The weight average molecular weight of the obtained copolymer (A3) was 1,700,000. A battery separator was obtained in the same manner as in Example 1 except that the coating liquid (E) in which the copolymer (A1) was replaced with the copolymer (A3) was used in the preparation of the coating liquid.
  • copolymer (A4) was synthesized as follows. The molar ratio of vinylidene fluoride / hexafluoropropylene / maleic acid monomethyl ester was 98.0 / 1.5 / 0.5 by suspension polymerization using vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester as starting materials. Thus, a copolymer (A4) was synthesized. The weight average molecular weight of the obtained copolymer (A4) was 1,900,000. A battery separator was obtained in the same manner as in Example 1 except that the coating liquid (F) in which the copolymer (A1) was replaced with the copolymer (A4) was used in the preparation of the coating liquid.
  • Example 9 In the preparation of the coating liquid, the blending ratio of the copolymer (A1) and the copolymer (B1) was 28.0 parts by mass of the copolymer (A1) and 2.0 parts by mass of the copolymer (B1). A battery separator was obtained in the same manner as in Example 1 except that the working liquid (G) was used.
  • Example 10 In the preparation of the coating liquid, the content of alumina particles was set to 40% by volume with the solid content of the porous layer being 100% by volume, and 35.2 parts by mass of the copolymer (A1) and the copolymer (B1). A battery separator was obtained in the same manner as in Example 1 except that the coating liquid (H) in which 4.7 parts by mass and NMP was changed to 900 parts by mass was used.
  • Example 11 In the preparation of the coating liquid, the content of alumina particles is 75% by volume with the solid content of the porous layer being 100% by volume, and 11.4 parts by mass of copolymer (A1) and copolymer (B1).
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (I) in which 1.5 parts by mass and NMP was changed to 300 parts by mass was used.
  • copolymer (A5) was synthesized as follows. The molar ratio of vinylidene fluoride / hexafluoropropylene / maleic acid monomethyl ester was 98.4 / 1.5 / 0.1 by suspension polymerization using vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester as starting materials. Thus, a copolymer (A5) was synthesized. The weight average molecular weight of the obtained copolymer (A5) was 1,500,000.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (J) was used instead of the copolymer (A5) in the preparation of the coating liquid.
  • copolymer (A6) was synthesized as follows. The molar ratio of vinylidene fluoride / hexafluoropropylene / maleic acid monomethyl ester was 94.5 / 1.5 / 4.0 by suspension polymerization using vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester as starting materials. Thus, a copolymer (A6) was synthesized. The weight average molecular weight of the obtained copolymer (A6) was 1,500,000.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (K) in which the copolymer (A1) was replaced with the copolymer (A6) was used in the preparation of the coating liquid.
  • Example 14 The amount of extrusion of the first and second polyolefin resin solutions was adjusted, and a polyolefin three-layer fine layer having a layer thickness ratio of 10/80/10, a thickness of 7 ⁇ m, a porosity of 37%, and an air resistance of 120 seconds / 100 cm 3 A porous membrane D was obtained.
  • a battery separator was obtained in the same manner as in Example 1 except that the polyolefin three-layer microporous membrane D was used. The thickness of the battery separator was 10 ⁇ m.
  • Example 15 The amount of extrusion of the first and second polyolefin resin solutions was adjusted, and the layer thickness ratio was 10/80/10, the thickness was 16 ⁇ m, the porosity was 45%, and the air permeability resistance was 200 seconds / 100 cm 3.
  • a porous membrane E was obtained.
  • a battery separator was obtained in the same manner as in Example 1 except that the polyolefin three-layer microporous membrane E was used. The thickness of the battery separator was 19 ⁇ m.
  • Example 16 As the copolymer (B), a copolymer (B4) was synthesized as follows. A copolymer (B4) was synthesized by suspension polymerization using vinylidene fluoride and hexafluoropropylene as starting materials so that the molar ratio of vinylidene fluoride / hexafluoropropylene was 93.0 / 7.0. The weight average molecular weight of the obtained copolymer (B1) was 700,000. A battery separator was obtained in the same manner as in Example 1 except that the coating liquid (L) in which the copolymer (B1) was replaced with the copolymer (B4) was used in the preparation of the coating liquid.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (L) in which the copolymer (B1) was replaced with the copolymer (B4) was used in the preparation of the coating liquid.
  • Example 17 In preparation of the coating liquid, the alumina particles are replaced with plate-like boehmite particles (density 3.07 g / cm 3 ) having an average particle diameter of 1.0 ⁇ m and an average thickness of 0.4 ⁇ m, and the copolymer (A1) 31.5 mass. Battery separator was obtained in the same manner as in Example 1 except that the coating liquid (M) was used in an amount of 4.2 parts by weight of the copolymer (B1).
  • Example 18 In preparation of the coating liquid, the alumina particles are replaced with an average particle diameter of 0.4 ⁇ m, titania particles (density 4.23 g / cc), 25.3 parts by mass of the copolymer (A1), and the copolymer (B1) 3.4.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (N) in mass parts was used.
  • Example 19 In the preparation of the coating solution, the blending ratio of the copolymer (A1) and the copolymer (B1) was 29.0 parts by mass of the copolymer (A1) and 1.0 part by mass of the copolymer (B1). A battery separator was obtained in the same manner as in Example 1 except that the working liquid (O) was used.
  • Example 1 In the preparation of the first polyolefin resin solution, the thickness was 12 ⁇ m, the porosity was 44%, and the air resistance was the same as in Example 1 except that polypropylene was not used and the blending amount of the high-density polyethylene was 100% by mass.
  • a polyolefin three-layer microporous membrane F of 100 seconds / 100 cm 3 was obtained.
  • a battery separator was obtained in the same manner as in Example 1 except that the polyolefin three-layer microporous membrane F was used.
  • Example 2 In the preparation of the first polyolefin resin solution, the thickness was 12 ⁇ m, the porosity was 45%, in the same manner as in Example 1 except that the blending amount of polypropylene was 5 mass% and the blending amount of high-density polyethylene was 95 mass%.
  • a battery separator was obtained in the same manner as in Example 1 except that the polyolefin three-layer microporous membrane G was used.
  • Example 3 In the preparation of the first polyolefin resin solution, the thickness was 12 ⁇ m, the porosity was 37%, in the same manner as in Example 1 except that the blending amount of polypropylene was 80% by mass and the blending amount of high-density polyethylene was 20% by mass. A polyolefin three-layer microporous membrane H having an air resistance of 815 sec / 100 cm 3 was obtained. A battery separator was obtained in the same manner as in Example 1 except that the polyolefin three-layer microporous membrane H was used.
  • Example 5 In the preparation of the coating liquid, alumina particles were added so that the solid content of the porous layer was 100% by volume to 95% by volume, and 2.0 parts by mass of the copolymer (A1), 0. A battery separator was obtained in the same manner as in Example 1 except that the coating liquid (Q) in which 3 parts by mass and NMP was changed to 250 parts by mass was used.
  • copolymer (A7) was synthesized as follows.
  • a copolymer (A7) was synthesized by suspension polymerization using vinylidene fluoride and hexafluoropropylene as starting materials so that the molar ratio of vinylidene fluoride / hexafluoropropylene was 98.5 / 1.5.
  • the weight average molecular weight of the obtained copolymer (A7) was 1,500,000.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (S) in which the copolymer (A1) was replaced with the copolymer (A7) was used in the preparation of the coating liquid.
  • Example 8 In the preparation of the coating liquid, the coating liquid (T) prepared without using the copolymer (B) by replacing the copolymer (A) with 30.0 parts by weight of polyvinylidene fluoride (weight average molecular weight 1,500,000) A battery separator was obtained in the same manner as in Example 1 except that was used.
  • copolymer (A8) was synthesized as follows. The molar ratio of vinylidene fluoride / hexafluoropropylene / maleic acid monomethyl ester was 98.0 / 1.5 / 0.5 by suspension polymerization using vinylidene fluoride, hexafluoropropylene and maleic acid monomethyl ester as starting materials. Thus, a copolymer (A8) was synthesized. The weight average molecular weight of the obtained copolymer (A8) was 650,000.
  • a battery was prepared in the same manner as in Example 1 except that in the preparation of the coating liquid, the copolymer (A1) was replaced with the copolymer (A8) and the coating liquid (U) in which NMP was changed to 500 parts by mass was used. A separator was obtained.
  • copolymer (B5) was synthesized as follows.
  • a copolymer (B5) was synthesized by suspension polymerization using vinylidene fluoride and hexafluoropropylene as starting materials so that the molar ratio of vinylidene fluoride / hexafluoropropylene was 93.0 / 7.0.
  • the weight average molecular weight of the obtained copolymer (B5) was 70,000.
  • a battery separator was obtained in the same manner as in Example 1 except that the coating liquid (V) was used instead of the copolymer (B5) in the preparation of the coating liquid.
  • Comparative Example 11 A battery separator was obtained in the same manner as in Comparative Example 1 except that the polyolefin three-layer microporous membrane D was used. The thickness of the battery separator was 10 ⁇ m.
  • composition and characteristics of the polyolefin multilayer microporous membrane used in the above Examples and Comparative Examples are shown in Table 1, and the structure of the copolymer (A) and copolymer (B) of the porous layer, the weight average molecular weight, coating
  • Table 2 The composition of the liquid and the characteristics of the obtained battery separator are shown in Table 2.
  • the battery separator of the present embodiment when used in a non-aqueous electrolyte secondary battery, satisfies the peeling force during drying and the bending strength when wet, and the adhesion between the separators of the polyolefin multilayer microporous membrane and the porous layer. And the separator for batteries which is excellent in the adhesiveness between a separator and an electrode, and is excellent in short circuit tolerance can be provided. Therefore, the battery separator according to the present embodiment can be suitably used even when a larger size and a higher capacity of a battery (particularly a laminate type battery) are required in the future.

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Abstract

La présente invention aborde le problème de la fourniture d'un séparateur pour piles, qui présente une excellente capacité de liaison et une excellente résistance aux courts-circuits. La présente invention concerne un séparateur pour piles, qui est pourvu d'une membrane microporeuse en polyoléfine et d'une couche poreuse qui est disposée sur au moins une surface de la membrane microporeuse en polyoléfine, et qui est configurée de telle sorte que : la membrane microporeuse en polyoléfine est composée d'une membrane microporeuse multicouche en polyoléfine qui présente une structure à trois couches dans laquelle une première couche microporeuse, une deuxième couche microporeuse et une autre première couche microporeuse sont stratifiées dans cet ordre ; les premières couches microporeuses sont formées à partir d'une première résine de polyoléfine qui contient un polyéthylène et un polypropylène ; la teneur du polypropylène est comprise entre 10 % en masse et 50 % en masse (inclus) par rapport à la masse totale de la première résine de polyoléfine ; la deuxième couche microporeuse est formée uniquement à partir d'une résine de polyéthylène ; et la couche poreuse contient un copolymère fluorure de vinylidène-hexafluoropropylène (A), un copolymère fluorure de vinylidène-hexafluoropropylène (B) et des particules inorganiques.
PCT/JP2018/009674 2017-03-17 2018-03-13 Séparateur de piles, corps d'électrode et pile secondaire à électrolyte non aqueux WO2018168835A1 (fr)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110416470A (zh) * 2019-08-07 2019-11-05 江苏厚生新能源科技有限公司 电池隔膜及其制备工艺、降低二氯甲烷消耗量的改进方法
CN110571395A (zh) * 2019-08-30 2019-12-13 瑞浦能源有限公司 一种锂离子电池隔膜及其制备方法
WO2020149294A1 (fr) * 2019-01-16 2020-07-23 東レ株式会社 Film microporeux multicouche de polyoléfine et procédé de production de celui-ci
JP2020155208A (ja) * 2019-03-18 2020-09-24 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
CN114709565A (zh) * 2022-06-07 2022-07-05 中材锂膜(宁乡)有限公司 有机/无机复合层多孔隔膜、其制备方法及电化学装置
WO2023002818A1 (fr) * 2021-07-19 2023-01-26 東レ株式会社 Membrane microporeuse multicouche en polyoléfine, membrane microporeuse multicouche en polyoléfine stratifiée, et séparateur de batterie

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7461381B2 (ja) * 2020-01-08 2024-04-03 旭化成株式会社 無機塗工層架橋セパレータ

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001307735A (ja) * 2000-04-17 2001-11-02 Matsushita Electric Ind Co Ltd リチウム二次電池
WO2013058368A1 (fr) * 2011-10-21 2013-04-25 帝人株式会社 Séparateur de batterie secondaire non aqueuse et batterie secondaire non aqueuse
JP2014041818A (ja) * 2012-07-25 2014-03-06 Samsung Sdi Co Ltd リチウム二次電池用セパレータ、及びこれを含むリチウム二次電池
WO2015194667A1 (fr) * 2014-06-20 2015-12-23 東レバッテリーセパレータフィルム株式会社 Film microporeux multicouche en polyoléfine, son procédé de production, et séparateur de cellule
WO2016002567A1 (fr) * 2014-06-30 2016-01-07 帝人株式会社 Séparateur pour piles rechargeables à électrolyte non aqueux et pile rechargeable à électrolyte non aqueux
WO2016042914A1 (fr) * 2014-09-19 2016-03-24 株式会社クレハ Latex aqueux, stratifié de séparateur/couche intermédiaire, et structure pour batteries rechargeables à électrolyte non aqueux
WO2017002947A1 (fr) * 2015-07-02 2017-01-05 帝人株式会社 Séparateur pour piles rechargeables à électrolyte non aqueux, pile rechargeable à électrolyte non aqueux, et procédé de fabrication de pile rechargeable à électrolyte non aqueux

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5342088B2 (fr) 1973-09-25 1978-11-09
JP3248570B2 (ja) 1997-10-09 2002-01-21 日本電気株式会社 半導体装置の製造方法
CA2615495C (fr) * 2005-07-15 2014-02-25 Tonen Chemical Corporation Membrane microporeuse multicouche constituee de polyolefines et separateur pour batterie
US20120003525A1 (en) * 2009-03-17 2012-01-05 Tomoegawa Co., Ltd. Separator for an electricity storage device and method of manufacturing same
JP5427046B2 (ja) 2010-01-14 2014-02-26 日立マクセル株式会社 非水電解質電池及びその製造方法
WO2013058367A1 (fr) 2011-10-21 2013-04-25 帝人株式会社 Séparateur de batterie secondaire non aqueuse et batterie secondaire non aqueuse
US20140315068A1 (en) 2011-10-21 2014-10-23 Teijin Limited Non-aqueous secondary battery separator and non-aqueous secondary battery
SG11201406050RA (en) * 2012-03-30 2014-11-27 Toray Battery Separator Film Multilayered microporous polyolefin film
JP6088759B2 (ja) * 2012-06-29 2017-03-01 Ｊｘエネルギー株式会社 リチウムイオン二次電池用セパレータの製造方法
US9385358B2 (en) * 2012-07-25 2016-07-05 Samsung Sdi Co., Ltd. Separator for rechargeable lithium battery, and rechargeable lithium battery including the same
KR20150058316A (ko) * 2012-09-20 2015-05-28 셀가드 엘엘씨 박형 배터리 분리막 및 방법
CN103441230B (zh) * 2013-08-21 2016-03-09 东莞新能源科技有限公司 有机/无机复合多孔隔离膜及其制备方法及电化学装置
SG11201606671PA (en) * 2014-05-30 2016-10-28 Toray Battery Separator Film Polyolefin multilayer microporous membrane and battery separator
CN107210414A (zh) 2015-03-24 2017-09-26 帝人株式会社 非水系二次电池用隔膜及非水系二次电池
KR102190595B1 (ko) * 2015-08-11 2020-12-14 도레이 카부시키가이샤 전지용 세퍼레이터
CN108352484B (zh) 2015-11-11 2021-08-06 帝人株式会社 非水系二次电池用隔膜及非水系二次电池

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001307735A (ja) * 2000-04-17 2001-11-02 Matsushita Electric Ind Co Ltd リチウム二次電池
WO2013058368A1 (fr) * 2011-10-21 2013-04-25 帝人株式会社 Séparateur de batterie secondaire non aqueuse et batterie secondaire non aqueuse
JP2014041818A (ja) * 2012-07-25 2014-03-06 Samsung Sdi Co Ltd リチウム二次電池用セパレータ、及びこれを含むリチウム二次電池
WO2015194667A1 (fr) * 2014-06-20 2015-12-23 東レバッテリーセパレータフィルム株式会社 Film microporeux multicouche en polyoléfine, son procédé de production, et séparateur de cellule
WO2016002567A1 (fr) * 2014-06-30 2016-01-07 帝人株式会社 Séparateur pour piles rechargeables à électrolyte non aqueux et pile rechargeable à électrolyte non aqueux
WO2016042914A1 (fr) * 2014-09-19 2016-03-24 株式会社クレハ Latex aqueux, stratifié de séparateur/couche intermédiaire, et structure pour batteries rechargeables à électrolyte non aqueux
WO2017002947A1 (fr) * 2015-07-02 2017-01-05 帝人株式会社 Séparateur pour piles rechargeables à électrolyte non aqueux, pile rechargeable à électrolyte non aqueux, et procédé de fabrication de pile rechargeable à électrolyte non aqueux

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020149294A1 (fr) * 2019-01-16 2020-07-23 東レ株式会社 Film microporeux multicouche de polyoléfine et procédé de production de celui-ci
CN112512807A (zh) * 2019-01-16 2021-03-16 东丽株式会社 聚烯烃多层微多孔膜及其制造方法
JPWO2020149294A1 (ja) * 2019-01-16 2021-12-02 東レ株式会社 ポリオレフィン多層微多孔膜およびその製造方法
EP3912813A4 (fr) * 2019-01-16 2022-10-12 Toray Industries, Inc. Film microporeux multicouche de polyoléfine et procédé de production de celui-ci
JP7352196B2 (ja) 2019-01-16 2023-09-28 東レ株式会社 ポリオレフィン多層微多孔膜
JP2020155208A (ja) * 2019-03-18 2020-09-24 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
CN110416470A (zh) * 2019-08-07 2019-11-05 江苏厚生新能源科技有限公司 电池隔膜及其制备工艺、降低二氯甲烷消耗量的改进方法
CN110416470B (zh) * 2019-08-07 2022-03-11 江苏厚生新能源科技有限公司 电池隔膜及其制备工艺、降低二氯甲烷消耗量的改进方法
CN110571395A (zh) * 2019-08-30 2019-12-13 瑞浦能源有限公司 一种锂离子电池隔膜及其制备方法
WO2023002818A1 (fr) * 2021-07-19 2023-01-26 東レ株式会社 Membrane microporeuse multicouche en polyoléfine, membrane microporeuse multicouche en polyoléfine stratifiée, et séparateur de batterie
CN114709565A (zh) * 2022-06-07 2022-07-05 中材锂膜(宁乡)有限公司 有机/无机复合层多孔隔膜、其制备方法及电化学装置
CN114709565B (zh) * 2022-06-07 2022-09-02 中材锂膜(宁乡)有限公司 有机/无机复合层多孔隔膜、其制备方法及电化学装置

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TWI744505B (zh) 2021-11-01
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