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WO2014208926A1 - Separator comprising coating layer, and battery using same separator - Google Patents

Separator comprising coating layer, and battery using same separator Download PDF

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Publication number
WO2014208926A1
WO2014208926A1 PCT/KR2014/005364 KR2014005364W WO2014208926A1 WO 2014208926 A1 WO2014208926 A1 WO 2014208926A1 KR 2014005364 W KR2014005364 W KR 2014005364W WO 2014208926 A1 WO2014208926 A1 WO 2014208926A1
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WIPO (PCT)
Prior art keywords
coating layer
separator
porous
battery
negative electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/KR2014/005364
Other languages
French (fr)
Korean (ko)
Inventor
이병민
김하나
박명국
정준호
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cheil Industries Inc
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Cheil Industries Inc
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Publication of WO2014208926A1 publication Critical patent/WO2014208926A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/42—Acrylic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—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
    • H01M50/411—Organic material
    • H01M50/429—Natural 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
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing 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
    • H01M50/449—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
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a separator comprising a coating layer and a battery using the separator.
  • a separator for an electrochemical cell refers to an interlayer membrane which maintains ion conductivity while allowing the cathode and the cathode to be separated from each other in the cell, thereby allowing the battery to be charged and discharged.
  • the problem to be solved by the present invention is to provide a separator that is excellent in heat resistance and also excellent adhesion to the electrode to improve the shape retention and stability of the battery when used in the battery
  • Another object of the present invention is to provide a secondary battery having improved shape preservation and stability, including a separator having excellent adhesion to the electrode.
  • a porous base film A first coating layer formed on one surface of the porous base film and containing inorganic particles; And a second coating layer formed on the other side of the porous base film and containing a single or a mixture thereof selected from the group consisting of styrene-butadiene rubber, carboxy methyl cellulose, poly butyl acrylate and ethylene vinyl acetate, 2 provides a porous separator having an adhesion between the coating layer and the negative electrode of the battery is 20 gf / cm or more.
  • a cathode, a cathode, a separator and an electrolyte the separator comprises a coating layer formed on the cathode, the second coating layer is styrene-butadiene rubber, carboxy methyl cellulose, poly It provides an electrochemical cell containing a single or a mixture thereof selected from the group consisting of butyl acrylate and ethylene vinyl acetate, wherein the adhesion between the second coating layer and the negative electrode is at least 20 gf / cm.
  • a coating layer containing inorganic particles is formed on one surface of the base film, thereby improving the heat resistance of the separator, and a coating layer containing an organic binder including styrene-butadiene rubber is formed on the other side of the base film.
  • the present invention uses the separator having excellent heat resistance and adhesion to the electrode for the battery, thereby improving the resistance to thermal contraction of the separator generated when the battery is overheated, and has an effect of providing a battery having excellent shape preservation and stability.
  • a porous base film A first coating layer formed on one surface of the porous base film and containing inorganic particles; And a second coating layer formed on the other side of the porous base film and containing a single or a mixture thereof selected from the group consisting of styrene-butadiene rubber, carboxy methyl cellulose, poly butyl acrylate and ethylene vinyl acetate, 2 provides a porous separator having an adhesion between the coating layer and the negative electrode of the battery is 20 gf / cm or more.
  • Porous base film according to an embodiment of the present invention may be prepared by extruding and stretching the composition for the base film to form a fine pore in the base film.
  • a polyolefin resin composition can be used, for example.
  • the polyolefin resin composition may be composed of only one or more polyolefin resins or may be a mixed composition including one or more polyolefin resins and other resins and / or inorganic materials other than the polyolefin resin.
  • Non-limiting examples of polyolefin resins include polyethylene (PE), polypropylene (PP) or poly-4-methyl-1-pentene (poly-4-methyl-1-pentene, PMP). have. These may be used alone or in combination of two or more thereof. That is, polyolefin resin may be used alone, or a copolymer or a mixture thereof may be used.
  • Non-limiting examples of other resins except polyolefins include polyamide (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polychlorotrifluoroethylene, PCTFE), Polyoxymethylene (POM), Polyvinyl fluoride (PVF), Polyvinylidene fluoride (PVDF), Polycarbonate (PC), Polyarylate (PAR) ), Polysulfone (PSU), polyetherimide (PEI) and the like. These may be used alone or in combination of two or more thereof.
  • PA polyamide
  • PBT polybutylene terephthalate
  • PET polyethylene terephthalate
  • PCTFE polychlorotrifluoroethylene
  • POM Polyoxymethylene
  • PVF Polyvinyl fluoride
  • PVDF Polyvinylidene fluoride
  • PC Polycarbonate
  • PAR Polyarylate
  • PSU Polysulfone
  • PEI polyetherimide
  • the method for producing the base film is largely classified into a wet method and a dry method.
  • the polyolefin sheet is stretched at a low temperature to induce fine cracks between the lamellar, which is a crystal part of the polyolefin, to form fine pores, or the inorganic particles are mixed with a polyolefin resin to make a film, and then at a low temperature. It extends
  • the wet method mixes polyolefin resins and diluents (low molecular weight organic materials having a molecular structure similar to polyolefins, such as liquid paraffin, etc.) at a high temperature at which the polyolefin resin composition is melted to form a single phase and polyolefin during the cooling process.
  • Phase separation of and diluent refers to a method of extracting the diluent to form voids therein.
  • the method of forming the fine pores on the polyolefin-based substrate film according to an embodiment of the present invention is not particularly limited and may be in accordance with methods commonly used in the art, for example, may be in accordance with the wet method.
  • the thickness of the separator can be controlled thinly and uniformly compared to the dry method, and the size of the generated pores can be uniformly controlled, and the porous membrane can be manufactured more excellent in mechanical strength.
  • a polyolefin-based base film may be used, and specifically, a single polyethylene film, a polypropylene single film, a polyethylene / polypropylene double film, a polypropylene / polyethylene / polypropylene triple Membranes selected from the group consisting of membranes and polyethylene / polypropylene / polyethylene triple membranes can be used.
  • the thickness of the porous base film according to an embodiment of the present invention may be 1 to 30 ⁇ m, specifically 5 to 20 ⁇ m. Within the thickness range, it is possible to form a separator having an appropriate thickness to prevent a short circuit between the positive electrode and the negative electrode and to improve the stability of the battery, and the thickness of the separator may be too thick to prevent the internal resistance of the battery from increasing.
  • the first coating layer is a coating layer containing an organic binder and inorganic particles, and is formed on one surface of a separator that is adhered to an anode of the battery when applied to an electrochemical cell.
  • the kind of the inorganic particles included in the first coating layer is not particularly limited, and inorganic particles commonly used in the art may be used.
  • Non-limiting examples of the inorganic particles include Al 2 O 3 , SiO 2 , B 2 O 3 , Ga 2 O 3 , TiO 2 or SnO 2 . These may be used alone or in combination of two or more thereof, for example, Al 2 O 3 (alumina) may be used.
  • the size of the inorganic particles is not particularly limited, but the average particle diameter may be 10 nm to 2,000 nm, specifically, 100 nm to 1,000 nm, more specifically 200 to 500 nm.
  • the inorganic particles in the size range it is possible to prevent the dispersibility and coating processability of the inorganic particles in the coating liquid to be lowered and the thickness of the coating layer is appropriately adjusted to prevent the reduction of mechanical properties and increase of electrical resistance. Can be.
  • the size of the pores generated in the separator is appropriately adjusted, there is an advantage that can lower the probability of the internal short circuit occurs during charging and discharging of the battery.
  • the inorganic particles may be contained in 50 to 95 parts by weight, specifically, may be contained in 70 to 90 parts by weight. Within this range, the heat resistance of the separator may be sufficiently improved, and at the same time, the adhesive force with the electrode may be increased.
  • the organic binder included in the first coating layer is not particularly limited as long as it is a component that does not readily dissolve in the electrolyte while having adhesion to the electrode.
  • polyvinylidene fluoride PVdF
  • PVDF-HFP polyvinylidene fluoride-hexafluoropropylene
  • PVDF-HFP polyvinylidene fluoride-trichloroethylene
  • PVdF-TCE polyvinylidene fluoride-chlorotrifluoroethylene copolymer
  • PVFF-CTFE polymethylmethacrylate
  • PMMA polyacrylonitrile
  • PAN Polyvinylpyrrolidone
  • PVA Polyvinyl Acetate
  • PEO Polyethylene Oxide
  • Ethylene-vinyl acetate copolymer Cellulose Acetate Cellulose acetate (CA), Cellulose acetate butyrate (CAB), Cellulose Tat
  • polyvinylidene fluoride-hexafluoropropylene copolymer can be used.
  • the polyvinylidene fluoride-hexafluoropropylene copolymer may have a weight average molecular weight of 800,000 g / mol or less, and specifically 600,000 g / mol to 800,000 g / mol. Within the molecular weight range, there is an advantage in that the battery can be produced in which the electric force output is efficiently due to the electrolyte impregnation of the separator.
  • the content of each of the polyvinylidene fluoride and the hexafluoropropylene is not particularly limited, but for example, Hexafluoropropylene may be contained in an amount of 0.1 to 40% by weight based on the total weight.
  • a polyvinylidene fluoride-hexafluoropropylene copolymer and a polyvinylidene fluoride homopolymer may be used as an organic binder included in the first coating layer.
  • the polyvinylidene fluoride homopolymer may be used having a weight average molecular weight of 1,000,000 g / mol or more, specifically, it may be used from 1,000,000 g / mol to 1,200,000 g / mol.
  • the adhesion between the coating layer and the polyolefin-based substrate film is enhanced to reduce shrinkage due to heat, and the adhesion between the coating layer and the electrode is also excellent, thereby effectively suppressing a short circuit between the anode and the cathode.
  • the polyvinylidene fluoride homopolymer is smoothly dissolved in a solvent within the above molecular weight range so that an excessive high boiling point solvent is not required, thereby preventing a process defect problem that may occur during drying.
  • the organic binder may be contained in 5 to 50 parts by weight, for example 10 to 30 parts by weight. Within the above range, the forming force and the adhesive force of the coating layer are excellent.
  • the second coating layer contains an organic binder and is formed on one surface of the separator that is adhered to the negative electrode of the battery when applied to the electrochemical cell.
  • the organic binder included in the second coating layer may be different from the organic binder of the first coating layer.
  • As the organic binder included in the second coating layer for example, styrene-butadiene rubber (SBR), carboxy methyl cellulose (CMC), polybutyl acrylate (PBMA), ethylene Vinyl acetate (Ethylene Vinyl Acrylate, EVA) and the like. These may be used alone or in combination of two or more thereof, for example, styrene-butadiene rubber may be used.
  • carboxymethyl cellulose when used as the organic binder in the second coating layer, carboxymethyl cellulose may be used together. Since styrene-butadiene rubber is an aqueous binder, when used alone, the viscosity of the coating agent may be weakened. Therefore, the use of carboxy methyl cellulose, which additionally imparts adhesion, may increase the viscosity of the coating agent. .
  • the second coating layer may contain inorganic particles as needed, and may use the same or different inorganic particles as the first coating layer.
  • the inorganic particles may be included in an amount of 50 to 95 parts by weight, specifically 70 to 90 parts by weight, based on 100 parts by weight of the second coating layer.
  • the adhesion between the second coating layer and the negative electrode of the battery may be 20 gf / cm or more, for example, 20 gf / cm to 50 gf / cm.
  • the coating layer and the electrode may be sufficiently strongly bonded to prevent short circuit between the positive electrode and the negative electrode.
  • the battery refers to an electrochemical cell filled with an electrolyte including a positive electrode, a negative electrode, and a separator, and detailed descriptions of the battery, the electrode of the battery, and the like will be replaced with the following description.
  • the second coating layer of the separator included in the battery may have an adhesive strength of about 20 gf / cm or more with the negative electrode of the battery.
  • the method for measuring the adhesive force between the second coating layer and the electrode is not particularly limited, and a method commonly used in the art may be used.
  • a non-limiting example of a method for measuring the adhesion between the second coating layer and the electrode is as follows: the prepared separator is placed between the positive electrode and bonded to prepare a positive electrode / separator / cathode form, and then aluminum pouch (pouch) ). Then, the electrolyte solution is poured into it and the aluminum pouch is sealed to prepare a single cell. After leaving it for 12 hours under pressure at 50 ° C., 100 kgf / cm 2 , and 20 seconds, the single cell was disassembled and the anode / separator / cathode adhered to each other (MD) about 2.5 cm ⁇ length (TD). After cutting to about 7 cm and firmly attached to the glass plate using a transparent double-sided tape (3M), a tensile strength meter (UTM; Universal Test Machine) can be used to measure the adhesion between the coating layer and the electrode.
  • UDM tensile strength meter
  • the separation force of the separator may be 300 gf / cm or more, specifically 300 to 800 gf / cm. Within this range, it is possible to prevent separation between the coating layer and the base film which may occur when the battery is overheated, thereby preventing the short circuit of the electrode and improving the thermal stability.
  • Method for measuring the peel force of the separator is not particularly limited, it can be used a method commonly used in the art.
  • a non-limiting example of the method for measuring the peel force is as follows: The prepared separator is cut to 2.5 cm x 7 cm (TD) to prepare 10 samples each. Each sample was firmly attached to the glass plate using a transparent double-sided tape (3M), and then the force required to peel each separator was calculated using a universal test machine (UTM) and the average value thereof was calculated. It can be done in a way.
  • the separator may have a thermal contraction rate of 7% or less in the longitudinal direction (MD) and the transverse direction (TD) after being left at 120 ° C. for 1 hour, for example, 6% It may be less than, specifically 5% or less in the direction of any one of the longitudinal or transverse direction. Within this range, there is an advantage of effectively preventing a short circuit of the electrode to improve the safety of the battery.
  • the method for measuring the thermal contraction rate of the separator is not particularly limited, it can be used a method commonly used in the art.
  • a non-limiting example of a method for measuring the thermal contraction rate of the separator is as follows: The prepared separator is cut to about 5 cm in width (MD) x 5 cm in length (TD), which is a chamber at 120 ° C. After storing for 1 hour, the shrinkage in the MD direction and the TD direction of the separator can be measured by calculating the heat shrinkage rate.
  • an organic binder is added to the first solvent and stirred to prepare a polymer solution, and separately from the polymer solution, inorganic particles are added to the second solvent and dispersed to prepare an inorganic dispersion. At this time, it can be milled using a bead mill for the dispersion of the inorganic particles.
  • Acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone as the first solvent and the second solvent N-methyl-2-pyrrolidone, NMP), cyclohexane (cyclohexane) and water selected from the group consisting of, or a mixture thereof may be used, but is not limited thereto.
  • the polymer solution, the inorganic dispersion and the third solvent may be mixed in a predetermined ratio to prepare a coating solution, and the coating solution may be used to form a coating layer on the base film.
  • the first to third solvents may be the same, for example, acetone may be used.
  • a coating solution may be prepared by adding and stirring the organic binder and the inorganic particles to the first solvent according to a choice by those skilled in the art. When the polymer solution and the inorganic dispersion are separately prepared, the dispersibility and crude liquid stability of the inorganic particles may be excellent.
  • the method of forming the coating layer on the base film is not particularly limited, and a method commonly used in the art may be used. For example, a dip coating method, a die coating method, a roll coating method, or a comma coating method may be used, and these may be applied alone or by mixing two or more methods. .
  • a non-limiting example of preparing a porous separator having an asymmetric coating layer according to an embodiment of the present invention is as follows: A first coating agent on a surface of the polyethylene base film (Celgard PE) having a thickness of 9 ⁇ m in contact with the positive electrode of the battery; Coated with a die coating method to form a first coating layer, and then coated with a die coating method to apply a second coating agent to a surface of the base film in contact with the negative electrode of the battery, followed by drying.
  • a second coating layer it is possible to manufacture a porous separator having an asymmetric coating layer formed on both sides.
  • an electrochemical cell including a porous separator, a pole, and a cathode including the coating layer and filled with an electrolyte is provided.
  • the kind of the electrochemical cell is not particularly limited, and may be a battery of a kind known in the art.
  • the electrochemical battery according to an embodiment of the present invention may be, for example, a lithium secondary battery such as a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.
  • the method for manufacturing the electrochemical cell according to an example of the present invention is not particularly limited, and a method commonly used in the art according to an example of the present invention may be used.
  • a non-limiting example of a method of manufacturing the electrochemical cell is as follows: A separator comprising the organic and inorganic mixture coating layer according to an example of the present invention is placed between the positive electrode and the negative electrode of the cell, and then the electrolyte solution.
  • the battery can be prepared by filling in the following manner.
  • the electrode constituting the electrochemical cell according to an embodiment of the present invention may be manufactured in a form in which an electrode active material is bound to an electrode current collector by a method commonly used in the technical field of the present invention.
  • the cathode active material of the electrode active material according to an embodiment of the present invention is not particularly limited, and a cathode active material commonly used in the technical field of the present invention may be used.
  • the positive electrode includes a positive electrode active material capable of reversibly inserting and detaching lithium ions, and the positive electrode active material may be at least one selected from cobalt, manganese, nickel, and a composite metal oxide with lithium. .
  • the solid solution ratio between the metals may be various, and in addition to these metals, Mg, Al, Co, Ni, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, An element selected from the group consisting of Fe, Sr, V, and rare earth elements may be further included.
  • the anode may be, for example, a composite metal oxide of a metal selected from the group consisting of lithium and Co, Ni, Mn, Al, Si, Ti, and Fe, and specifically, lithium cobalt oxide (LCO.) For example LiCoO 2 ), lithium nickel manganese cobalt oxide, NCM.
  • LiFePO 4 lithium nickel oxide (LNO, for example LiNiO 2 ) and the like.
  • the negative electrode includes a negative electrode active material capable of inserting and desorbing lithium ions, and the negative electrode active material includes crystalline or amorphous carbon, or a carbon-based negative electrode active material (thermally decomposed carbon, coke, graphite) and combustion of a carbon composite.
  • Organic polymer compounds, carbon fibers, tin oxide compounds, lithium metal or alloys of lithium and other elements can be used.
  • amorphous carbons include hard carbon, coke, mesocarbon microbeads (MCMB) fired at 1,500 ° C or lower, and mesophase pitch-based carbon fibers (MPCF).
  • the crystalline carbon includes a graphite material, and specific examples thereof include natural graphite, graphitized coke, graphitized MCMB, graphitized MPCF, and the like.
  • the negative electrode may include, for example, crystalline or amorphous carbon.
  • the positive electrode or the negative electrode may be prepared by dispersing a binder, a conductive material, and, if necessary, a thickener in a solvent in addition to an electrode active material to prepare an electrode slurry composition, and applying the slurry composition to an electrode current collector.
  • the binder, the conductive material and the thickener may be used as commonly used in the art.
  • the binder polyvinylidene-fluoride (PVdF), styrene-butadiene rubber (SBR), and the like, carbon black as a conductive material, and carbonate methyl cellulose as a thickener (Carbonate methyl cellulose, CMC) can be used.
  • the electrode current collector according to an embodiment of the present invention is not particularly limited, and an electrode current collector commonly used in the art may be used.
  • Non-limiting examples of the positive electrode current collector material of the electrode current collector may be a foil made of aluminum, nickel or a combination thereof.
  • Non-limiting examples of the negative electrode current collector material of the electrode current collector may be a foil produced by copper, gold, nickel, a copper alloy or a combination thereof.
  • the positive electrode current collector and the negative electrode current collector may be in the form of a foil or a mesh.
  • the electrolyte solution according to an embodiment of the present invention is not particularly limited, and an electrolyte solution for an electrochemical cell commonly used in the art may be used.
  • the electrolyte solution may be one in which a salt having a structure such as A + B ⁇ is dissolved or dissociated in an organic solvent.
  • Non-limiting examples of A + include a cation consisting of an alkali metal cation such as Li + , Na + or K + , or a combination thereof.
  • Non-limiting examples of the organic solvent include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dimethylformamide (Dimethylformamide, DMF), Dipropyl carbonate (DPC), Dimethyl sulfoxide (DMSO), Acetonitrile, Dimethoxyethane, Diethoxyethane, Tetrahydrofuran ( Tetrahydrofuran), N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC) or gamma-butyrolactone (-Butyrolactone), and the like. These may be used alone or in combination of two or more thereof.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • DMF dimethylformamide
  • DMF dimethylformamide
  • DPC Dipropyl carbonate
  • DMSO Dimethyl sulfoxide
  • a polyvinylidene fluoride-hexafluoropropylene copolymer (21216, Solvay Co., Ltd.) having a weight average molecular weight of 700,000 g / mol was added to acetone (coarse gold) by 10 wt%.
  • the first polymer solution was prepared by adding and stirring in a stirrer at a temperature of 25 ° C. for 4 hours.
  • Al 2 O 3 (LS235, Nippon Light Metal Co., Ltd.) was added to 25% by weight of acetone and milled and dispersed at 25 ° C. for 2 hours using a bead mill to prepare an inorganic dispersion.
  • a first coating agent a large purified gold company
  • styrene-butadiene rubber STYRON Co.
  • STYRON Co. Carboxymethyl cellulose
  • acetone Crystal Gold Co., Ltd.
  • the following first coating agent is coated on the surface of the battery in contact with the positive electrode of the battery, and then coated by a die coating method to form a first coating layer.
  • the second coating agent was coated on the surface in contact with the cathode, coated with a die coating method, and then dried to form a second coating layer, thereby preparing a porous separator having an asymmetric coating layer formed on both surfaces thereof.
  • Example 1 a polyvinylidene fluoride homopolymer (5130, Solvay Co., Ltd.) having a weight average molecular weight of 1.1 million g / mol was further added to the first polymer solution in preparing the first coating agent. 10% by weight of gold) and stirred in a stirrer at a temperature of 25 °C for 4 hours to prepare a second polymer solution.
  • the second polymer solution was used.
  • a polymer solution prepared by adding polybutyl methacrylate (Aldrich) to acetone at 10 wt% and stirring at a temperature condition of 40 ° C. for 2 hours in a stirrer was used.
  • a separator was prepared in the same manner as in Example 1, except that the mixture was mixed at a weight ratio of 3: 3 and stirred at 25 ° C. for 2 hours with a power mixer.
  • Al 2 O 3 LS235, Nippon Light Metal Co., Ltd.
  • Example 1 a separation membrane was prepared in the same manner as in Example 1 except for using the same coating agent as the first coating agent as the second coating agent.
  • Example 2 a separator was manufactured in the same manner as in Example 3, except that the same coating agent as the first coating agent was used as the second coating agent.
  • Example 1 polyvinylidene fluoride-hexafluoropropylene copolymer (21216, Solvay Co., Ltd.) was added to the acetone (coarse gold company) at 10 wt% as a second coating agent and stirred for 25 hours in a stirrer.
  • the coating layer composition of the separator according to Examples 1 to 4 and Comparative Examples 1 to 3 are summarized in Table 1 below.
  • the battery used in this experiment is a lithium secondary battery, and the production examples of the positive electrode and the negative electrode of the battery are as follows.
  • Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was cut to a width of 2.5 cm x 7 cm of TD to prepare 10 samples each. Anodes were also cut into 2.5 cm wide by 10 cm wide by TD to prepare 10 samples each.
  • the positive electrode was prepared by dispersing LiCoO 2 as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, and carbon black as a conductive agent in an N-methyl-2-pyrrolidone solvent at a weight ratio of 94: 3: 3. Was prepared.
  • the positive electrode active material slurry was coated on an aluminum foil having a thickness of 20 ⁇ m, dried, and rolled to prepare a positive electrode.
  • the prepared sample was measured by using a tensile strength meter (UTM; Universal Test Machine) to measure the force required to peel the positive electrode active material and to calculate the average value.
  • UDM Universal Test Machine
  • Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was cut into a horizontal (MD) 2.5 cm ⁇ a vertical (TD) 7 cm to prepare 10 samples each.
  • the negative electrode was also cut to 2.5 cm in width x 10 cm in length (TD) to prepare 10 samples each.
  • the negative electrode used herein was prepared by mixing a natural graphite spherical with a negative electrode active material, styrene-butadiene rubber as a binder and carboxymethyl cellulose as a thickener in a weight ratio of 97: 1.5: 1.5, and then dispersed in water to prepare a negative electrode active material slurry. The slurry was coated on a copper foil having a thickness of 10 ⁇ m, dried, and rolled to prepare a negative electrode.
  • the prepared sample was measured by using a tensile tester (UTM; Universal Test Machine) to measure the force required to peel the negative active material and calculate the average value thereof.
  • UTM Universal Test Machine
  • Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was cut to a width of 2.5 cm and a length of 7 cm to prepare a sample of 10 samples.
  • Each sample was firmly attached to the glass plate using a transparent double-sided tape (3M), and then the force required to peel each separator was calculated using a universal test machine (UTM) and the average value thereof was calculated. It was.
  • Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was prepared with 10 specimens cut at 10 different points with 5 cm width (MD) and 5 cm length (TD). After the specimens were left in an oven at 120 ° C. for 1 hour, the average thermal shrinkage was calculated by measuring the shrinkage in the MD and TD directions of the specimens.
  • Examples 1 to 4 are porous separators in which an asymmetric coating layer is formed in which an organic binder contained in a coating layer on one side of a porous base film and an organic binder contained in a coating layer on the other side are formed.
  • the binder was found to have an excellent peeling force of 300 gf / cm or more and an adhesive strength of the negative electrode of 20 gf / cm or more.
  • the thermal contraction rate of the embodiment is 7% or less in the longitudinal direction (MD, Machine Direction) and the transverse direction (TD, Transverse Direction), respectively, the thermal contraction rate of at least one direction is 5% or less, so that the stability of the separator by heat This excellence was confirmed.

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Abstract

The present invention relates to a separator which has excellent heat resistance and also excellent adhesion with electrodes, and thus, when used in a battery, improves shape retention and stability of the battery. In particular, the present invention relates to a porous separator comprising: a porous base film; a first coating layer formed on one side of the porous base film and containing inorganic particles; and a second coating layer formed on the other side of the porous base film and containing any one selected from the group consisting of: styrene-butadiene rubber, carboxymethyl cellulose, poly butyl acrylate, and ethylene vinyl acetate, or a mixture thereof, wherein the adhesive force between the second coating layer and a negative electrode of a battery is 20 gf/cm or greater.

Description

코팅층을 포함하는 분리막 및 상기 분리막을 이용한 전지Separator comprising a coating layer and a battery using the separator

본 발명은 코팅층을 포함하는 분리막 및 상기 분리막을 이용한 전지에 관한 것이다.The present invention relates to a separator comprising a coating layer and a battery using the separator.

전기 화학 전지용 분리막 (separator)은 전지 내에서 양극과 음극을 서로 격리시키면서 이온 전도도를 지속적으로 유지시켜 주어 전지의 충전과 방전이 가능하게 하는 중간막을 의미한다.A separator for an electrochemical cell refers to an interlayer membrane which maintains ion conductivity while allowing the cathode and the cathode to be separated from each other in the cell, thereby allowing the battery to be charged and discharged.

최근 전자 기기의 휴대성을 높이기 위한 전기 화학 전지의 경량화 및 소형화 추세와 더불어, 전기 자동차 등에의 사용을 위한 고출력 대용량 전지를 필요로 하는 경향이 있다. 이에, 전기 화학 전지용 분리막의 경우 그 두께를 얇게 하고 중량을 가볍게 하는 것이 요구되면서도 그와 동시에 고용량 전지의 생산을 위하여 열에 의한 형태 안정성이 우수할 것이 요구된다.In recent years, along with the trend of lightening and miniaturization of electrochemical cells for increasing the portability of electronic devices, there is a tendency to require high output large capacity batteries for use in electric vehicles. Accordingly, in the case of the separator for an electrochemical cell, it is required to reduce the thickness and light weight, and at the same time, it is required to have excellent form stability by heat for the production of a high capacity battery.

특히 분리막의 기재 필름으로 폴리올레핀계를 사용할 경우, 비교적 낮은 온도에서 필름이 멜트 다운 (melt down)되는 문제가 있어 이를 보완하고자 분리막의 내열성을 향상시키려는 연구가 진행되어 왔다. 이러한 분리막의 내열성 향상과 관련된 선행 기술로 대한민국 등록특허 제10-0775310호 등은 분리막의 기재 필름에 유기물 및 무기물 혼합 코팅층을 형성시킬 것을 제안하고 있다. 그러나, 상기 선행 기술과 같이 무기물이 포함된 코팅층의 경우 분리막의 내열성은 향상되더라도, 전극과의 접착력이 저하되어 분리막이 전극으로부터 이탈되는 등 전지의 형태 안정성이 나빠지는 문제가 있다.In particular, when a polyolefin-based film is used as the base film of the separator, there is a problem that the film melts down at a relatively low temperature. Therefore, studies to improve the heat resistance of the separator have been conducted to compensate for this problem. As a prior art related to improving the heat resistance of the separator, Korean Patent No. 10-0775310 et al. Proposes to form an organic and inorganic mixed coating layer on a base film of the separator. However, in the case of the coating layer containing the inorganic material as in the prior art, even if the heat resistance of the separator is improved, there is a problem in that the shape stability of the battery is deteriorated such that the adhesion force with the electrode is lowered and the separator is separated from the electrode.

따라서, 분리막의 내열성을 향상시키면서 전극과의 접착력 또한 우수한 코팅층을 포함하는 분리막의 개발이 요구되고 있는 실정이다.Accordingly, there is a demand for development of a separator including a coating layer having excellent adhesion to electrodes while improving heat resistance of the separator.

본 발명이 해결하고자 하는 과제는 내열성이 우수하면서도 전극과의 접착력 또한 우수하여 전지에 사용시 전지의 형태 보존성 및 안정성을 향상시키는 분리막을 제공하는 것이다The problem to be solved by the present invention is to provide a separator that is excellent in heat resistance and also excellent adhesion to the electrode to improve the shape retention and stability of the battery when used in the battery

본 발명이 해결하고자 하는 또 다른 과제는 전극과의 접착력이 우수한 분리막을 포함하여 형태 보존성 및 안정성이 향상된 이차전지를 제공하는 것이다. Another object of the present invention is to provide a secondary battery having improved shape preservation and stability, including a separator having excellent adhesion to the electrode.

본 발명의 일 예에 따르면, 다공성 기재 필름; 상기 다공성 기재 필름의 일면에 형성되고 무기 입자를 함유하는 제1 코팅층; 및 상기 다공성 기재 필름의 타면에 형성되고 스타이렌-부타디엔 고무, 카르복시 메틸 셀룰로오스, 폴리 부틸 아크릴레이트 및 에틸렌 바이닐 아세테이트로 이루어진 군으로부터 선택된 단독 또는 이들의 혼합물을 함유하는 제2 코팅층을 포함하며, 상기 제2 코팅층과 전지의 음극과의 접착력이 20 gf/cm이상인, 다공성 분리막을 제공한다.According to one embodiment of the present invention, a porous base film; A first coating layer formed on one surface of the porous base film and containing inorganic particles; And a second coating layer formed on the other side of the porous base film and containing a single or a mixture thereof selected from the group consisting of styrene-butadiene rubber, carboxy methyl cellulose, poly butyl acrylate and ethylene vinyl acetate, 2 provides a porous separator having an adhesion between the coating layer and the negative electrode of the battery is 20 gf / cm or more.

본 발명의 또 다른 일 예에 따르면, 양극, 음극, 분리막 및 전해질을 포함하며, 상기 분리막은 상기 음극 상에 형성된 코팅층을 포함하고, 상기 제2 코팅층은 스타이렌-부타디엔 고무, 카르복시 메틸 셀룰로오스, 폴리 부틸 아크릴레이트 및 에틸렌 바이닐 아세테이트로 이루어진 군으로부터 선택된 단독 또는 이들의 혼합물을 함유하며, 상기 제2 코팅층과 상기 음극과의 접착력이 20 gf/cm 이상인, 전기 화학 전지를 제공한다.According to another embodiment of the present invention, a cathode, a cathode, a separator and an electrolyte, the separator comprises a coating layer formed on the cathode, the second coating layer is styrene-butadiene rubber, carboxy methyl cellulose, poly It provides an electrochemical cell containing a single or a mixture thereof selected from the group consisting of butyl acrylate and ethylene vinyl acetate, wherein the adhesion between the second coating layer and the negative electrode is at least 20 gf / cm.

본 발명은 기재 필름의 일면에 무기 입자가 함유된 코팅층이 형성되어 있어 분리막의 내열성을 향상시키는 효과를 나타내며, 상기 기재 필름의 타면에는 스타이렌-부타디엔 고무를 포함하는 유기 바인더를 함유하는 코팅층이 형성되어 있어 전지의 전극, 특히 음극과의 접착력이 우수한 효과를 나타낸다.According to the present invention, a coating layer containing inorganic particles is formed on one surface of the base film, thereby improving the heat resistance of the separator, and a coating layer containing an organic binder including styrene-butadiene rubber is formed on the other side of the base film. The adhesive force with the electrode of a battery, especially a negative electrode, exhibits the outstanding effect.

또한, 본 발명은 상기 내열성 및 전극와의 접착력이 우수한 분리막을 전지에 이용함으로서, 전지의 과열시 발생하는 분리막의 열수축에 대한 저항성이 향상되고 형태 보존성 및 안정성이 우수한 전지를 제공하는 효과를 나타낸다.In addition, the present invention uses the separator having excellent heat resistance and adhesion to the electrode for the battery, thereby improving the resistance to thermal contraction of the separator generated when the battery is overheated, and has an effect of providing a battery having excellent shape preservation and stability.

이하, 본 발명에 대하여 보다 상세히 설명한다. 본 명세서에 기재되지 않은 내용은 본 발명의 기술 분야 또는 유사 분야에서 숙련된 자이면 충분히 인식하고 유추할 수 있는 것이므로 그 설명을 생략한다.Hereinafter, the present invention will be described in more detail. Content not described herein is omitted because it can be sufficiently recognized and inferred by those skilled in the art or similar fields of the present invention.

본 발명의 일 예에 따르면, 다공성 기재 필름; 상기 다공성 기재 필름의 일면에 형성되고 무기 입자를 함유하는 제1 코팅층; 및 상기 다공성 기재 필름의 타면에 형성되고 스타이렌-부타디엔 고무, 카르복시 메틸 셀룰로오스, 폴리 부틸 아크릴레이트 및 에틸렌 바이닐 아세테이트로 이루어진 군으로부터 선택된 단독 또는 이들의 혼합물을 함유하는 제2 코팅층을 포함하며, 상기 제2 코팅층과 전지의 음극과의 접착력이 20 gf/cm 이상인, 다공성 분리막을 제공한다.According to one embodiment of the present invention, a porous base film; A first coating layer formed on one surface of the porous base film and containing inorganic particles; And a second coating layer formed on the other side of the porous base film and containing a single or a mixture thereof selected from the group consisting of styrene-butadiene rubber, carboxy methyl cellulose, poly butyl acrylate and ethylene vinyl acetate, 2 provides a porous separator having an adhesion between the coating layer and the negative electrode of the battery is 20 gf / cm or more.

이하, 본 발명의 일 예에 따른 다공성 분리막에 대하여 구체적으로 설명한다.Hereinafter, a porous separator according to an example of the present invention will be described in detail.

다공성 기재 필름Porous base film

본 발명의 일 예에 따른 다공성 기재 필름은 기재 필름용 조성물을 압출하고 연신하여 기재 필름에 미세 포어를 형성하여 제조될 수 있다.Porous base film according to an embodiment of the present invention may be prepared by extruding and stretching the composition for the base film to form a fine pore in the base film.

상기 기재 필름용 조성물로는 예를 들어, 폴리올레핀계 수지 조성물을 사용할 수 있다. 폴리올레핀계 수지 조성물은 1 종 이상의 폴리올레핀계 수지만으로 이루어지거나, 1 종 이상의 폴리올리핀계 수지와 폴리올레핀계를 제외한 다른 수지 및/또는 무기물을 포함하는 혼합 조성물일 수 있다.As said composition for base films, a polyolefin resin composition can be used, for example. The polyolefin resin composition may be composed of only one or more polyolefin resins or may be a mixed composition including one or more polyolefin resins and other resins and / or inorganic materials other than the polyolefin resin.

폴리올레핀계 수지의 비제한적인 예로는 폴리에틸렌 (Polyethylene, PE), 폴리프로필렌(Polypropylene, PP) 또는 폴리-4-메틸-1-펜텐(poly-4-methyl-1-pentene, PMP) 등을 들 수 있다. 이들은 단독으로 사용되거나 2 종 이상이 혼합되어 사용될 수 있다. 즉, 폴리올레핀계 수지를 단독으로 사용하거나 이들의 공중합체 또는 혼합물 등을 사용할 수 있다. 폴리올레핀계를 제외한 다른 수지의 비제한적인 예로는 폴리아마이드(Polyamide, PA), 폴리부틸렌테레프탈레이트(Polybutylene terephthalate, PBT), 폴리에틸렌테레프탈레이트(Polyethyleneterephthalate, PET), 폴리클로로트리플루오로에틸렌(Polychlorotrifluoroethylene, PCTFE), 폴리옥시메틸렌(Polyoxymethylene, POM), 폴리비닐플루오라이드(Polyvinyl fluoride, PVF), 폴리비닐리덴플루오라이드(Polyvinylidene fluoride, PVdF), 폴리카보네이트(Polycarbonate, PC), 폴리아릴레이트(Polyarylate, PAR), 폴리설폰(polysulfone, PSU), 폴리에테르이미드(polyetherimide, PEI) 등을 들 수 있다. 이들은 단독으로 사용되거나 2 종 이상을 혼합하여 사용될 수 있다. Non-limiting examples of polyolefin resins include polyethylene (PE), polypropylene (PP) or poly-4-methyl-1-pentene (poly-4-methyl-1-pentene, PMP). have. These may be used alone or in combination of two or more thereof. That is, polyolefin resin may be used alone, or a copolymer or a mixture thereof may be used. Non-limiting examples of other resins except polyolefins include polyamide (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polychlorotrifluoroethylene, PCTFE), Polyoxymethylene (POM), Polyvinyl fluoride (PVF), Polyvinylidene fluoride (PVDF), Polycarbonate (PC), Polyarylate (PAR) ), Polysulfone (PSU), polyetherimide (PEI) and the like. These may be used alone or in combination of two or more thereof.

기재 필름용 조성물을 압출하여 필름 형성 후 미세 포어를 형성하는 방식에 따라, 기재 필름을 제조하는 방법은 크게 습식법과 건식법으로 분류된다.According to the method of extruding the composition for the base film to form fine pores after film formation, the method for producing the base film is largely classified into a wet method and a dry method.

구체적으로, 건식법은 폴리올레핀 시트를 만든 후 저온에서 연신하여 폴리올레핀의 결정 부분인 라멜라 사이에 미세한 크랙을 유발시켜 미세 공극을 형성시키거나, 폴리올레핀계 수지에 무기 입자를 혼합하여 필름을 만든 후 역시 저온에서 연신하여 폴리올레핀 수지와 무기 입자간의 계면에 미세한 크랙을 유발시켜 미세 공극을 형성시키는 방법을 말한다. 습식법은 폴리올레핀계 수지 조성물이 용융되는 고온에서 폴리올레핀계 수지와 다일루언트 (폴리올레핀과 유사한 분자 구조를 가지는 저분자량의 유기 물질, 예를 들어 유동 파라핀 등)를 혼련하여 단일상을 만들고 냉각 과정에서 폴리올레핀과 다일루언트를 상분리시킨 후 다일루언트를 추출하여 내부에 공극을 형성시키는 방법을 말한다.Specifically, in the dry method, the polyolefin sheet is stretched at a low temperature to induce fine cracks between the lamellar, which is a crystal part of the polyolefin, to form fine pores, or the inorganic particles are mixed with a polyolefin resin to make a film, and then at a low temperature. It extends | stretches and induces a micro crack at the interface between a polyolefin resin and an inorganic particle, and means a method of forming micro voids. The wet method mixes polyolefin resins and diluents (low molecular weight organic materials having a molecular structure similar to polyolefins, such as liquid paraffin, etc.) at a high temperature at which the polyolefin resin composition is melted to form a single phase and polyolefin during the cooling process. Phase separation of and diluent refers to a method of extracting the diluent to form voids therein.

본 발명의 일 예에 따른 폴리올레핀계 기재 필름에 미세 포어를 형성하는 방법은 특별히 제한되지 아니하며 당해 기술 분야에서 통상적으로 사용하는 방법에 따를 수 있으나, 예를 들어, 습식법에 따를 수 있다. 습식법에 의할 경우 건식법에 비하여 분리막의 두께를 얇고 균일하게 제어할 수 있으며 생성되는 포어의 크기를 균일하게 조절할 수 있고 기계적 강도가 보다 우수한 다공성 분리막을 제조할 수 있다.The method of forming the fine pores on the polyolefin-based substrate film according to an embodiment of the present invention is not particularly limited and may be in accordance with methods commonly used in the art, for example, may be in accordance with the wet method. In the wet method, the thickness of the separator can be controlled thinly and uniformly compared to the dry method, and the size of the generated pores can be uniformly controlled, and the porous membrane can be manufactured more excellent in mechanical strength.

본 발명의 일 예에 따른 기재 필름은 예를 들어, 폴리올레핀계 기재 필름을 사용할 수 있으며, 구체적으로, 폴리에틸렌 단일막, 폴리프로필렌 단일막, 폴리에틸렌/폴리프로필렌 이중막, 폴리프로필렌/폴리에틸렌/폴리프로필렌 삼중막 및 폴리에틸렌/폴리프로필렌/폴리에틸렌 삼중막으로 이루어진 군에서 선택되는 분리막을 사용할 수 있다.As the base film according to an embodiment of the present invention, for example, a polyolefin-based base film may be used, and specifically, a single polyethylene film, a polypropylene single film, a polyethylene / polypropylene double film, a polypropylene / polyethylene / polypropylene triple Membranes selected from the group consisting of membranes and polyethylene / polypropylene / polyethylene triple membranes can be used.

본 발명의 일 예에 따른 다공성 기재 필름의 두께는 1 내지 30 ㎛일 수 있으며, 구체적으로 5 내지 20 ㎛일 수 있다. 상기 두께 범위 내에서, 적절한 두께의 분리막을 형성하여 양극과 음극의 단락을 방지하고 전지의 안정성을 향상시킬 수 있으며, 분리막의 두께가 지나치게 두꺼워져 전지의 내부 저항이 증가하는 것을 방지할 수 있다.The thickness of the porous base film according to an embodiment of the present invention may be 1 to 30 ㎛, specifically 5 to 20 ㎛. Within the thickness range, it is possible to form a separator having an appropriate thickness to prevent a short circuit between the positive electrode and the negative electrode and to improve the stability of the battery, and the thickness of the separator may be too thick to prevent the internal resistance of the battery from increasing.

제1 코팅층First coating layer

제1 코팅층은 유기 바인더 및 무기 입자를 함유하는 코팅층으로서 전기 화학 전지에 적용시 전지의 양극에 접착되는 분리막 일면에 형성된다.The first coating layer is a coating layer containing an organic binder and inorganic particles, and is formed on one surface of a separator that is adhered to an anode of the battery when applied to an electrochemical cell.

제1 코팅층에 포함되는 무기 입자의 종류는 특별히 제한되지 아니하며 당해 기술 분야에서 통상적으로 사용하는 무기 입자를 사용할 수 있다. 상기 무기 입자의 비제한적인 예로는 Al2O3, SiO2, B2O3, Ga2O3, TiO2 또는 SnO2 등을 들 수 있다. 이들은 단독으로 사용되거나 2종 이상을 혼합하여 사용될 수 있으며, 예를 들어, Al2O3 (알루미나)를 사용할 수 있다.The kind of the inorganic particles included in the first coating layer is not particularly limited, and inorganic particles commonly used in the art may be used. Non-limiting examples of the inorganic particles include Al 2 O 3 , SiO 2 , B 2 O 3 , Ga 2 O 3 , TiO 2 or SnO 2 . These may be used alone or in combination of two or more thereof, for example, Al 2 O 3 (alumina) may be used.

무기 입자의 크기는 특별히 제한되지 아니하나, 평균 입경이 10 nm 내지 2,000 nm일 수 있고, 구체적으로, 100 nm 내지 1,000 nm, 보다 구체적으로 200 내지 500 nm일 수 있다. 상기 크기 범위의 무기 입자를 사용하는 경우, 코팅액 내에서의 무기 입자의 분산성 및 코팅 공정성이 저하되는 것을 방지할 수 있고 코팅층의 두께가 적절히 조절되어 기계적 물성의 저하 및 전기적 저항의 증가를 방지할 수 있다. 또한, 분리막에 생성되는 기공의 크기가 적절히 조절되어 전지의 충방전시 내부 단락이 일어날 확률을 낮출 수 있는 이점이 있다.The size of the inorganic particles is not particularly limited, but the average particle diameter may be 10 nm to 2,000 nm, specifically, 100 nm to 1,000 nm, more specifically 200 to 500 nm. In the case of using the inorganic particles in the size range, it is possible to prevent the dispersibility and coating processability of the inorganic particles in the coating liquid to be lowered and the thickness of the coating layer is appropriately adjusted to prevent the reduction of mechanical properties and increase of electrical resistance. Can be. In addition, the size of the pores generated in the separator is appropriately adjusted, there is an advantage that can lower the probability of the internal short circuit occurs during charging and discharging of the battery.

본 발명의 일 예에 따르면, 제1 코팅층 100 중량부에 대하여, 무기 입자는 50 내지 95 중량부로 함유될 수 있고, 구체적으로 70 내지 90 중량부로 함유될 수 있다. 상기 범위 내에서 분리막의 내열성을 충분히 향상시킬 수 있음과 동시에 전극과의 접착력이 증가될 수 있다.According to one embodiment of the present invention, with respect to 100 parts by weight of the first coating layer, the inorganic particles may be contained in 50 to 95 parts by weight, specifically, may be contained in 70 to 90 parts by weight. Within this range, the heat resistance of the separator may be sufficiently improved, and at the same time, the adhesive force with the electrode may be increased.

제1 코팅층에 포함되는 유기 바인더는 전극과의 접착력을 가지면서 전해액에 쉽게 용해되지 않는 성분이라면 특별히 제한되지 않는다. 예를 들어, 폴리비닐리덴 플루오라이드(Polyvinylidene fluoride, PVdF), 폴리비닐리덴 플루오라이드-헥사플루오로프로필렌(Polyvinylidene fluoride-hexafluoropropylene, PVdF-HFP), 폴리비닐리덴 플루오라이드-트리클로로에틸렌(Polyvinylidene fluoride-trichlorethylene, PVdF-TCE), 폴리비닐리덴플루오라이드-클로로트리플로로에틸렌공중합체(polyvinylidene fluoride-chlorotrifluoroethylene copolymer, PVdF-CTFE), 폴리메틸메타크릴레이트(Polymethylmethacrylate, PMMA), 폴리아크릴로니트릴(polyacrylonitrile, PAN), 폴리비닐피돌리돈(Polyvinylpyrrolidone, PVP), 폴리비닐아세테이트(Polyvinyl acetate, PVA), 폴리에틸렌옥사이드(Poly ethylene oxide, PEO), 에틸렌 비닐 아세테이트 공중합체 (Ethylene-vinyl acetate copolymer), 셀룰로오스 아세테이트(Cellulose acetate, CA), 셀룰로오스 아세테이트 부틸레이트(Cellulose acetate butyrate, CAB), 셀룰로오스 아세테이트 프로피오네이트(Cellulose acetate propionate, CAP), 시아노에틸풀루란(Cyanoethyl pullulan , CyEPL), 시아노에틸폴리비닐알콜 (Cyanoethylpolyvinylalcohol), 시아노에틸셀룰로오스 (Cyanoethylcellulose), 시아노에틸수크로오스 (Cyanoethylsucrose), 풀루란 (pullulan), 카르복실 메틸 셀룰로오스 (Carboxy methyl cellulose, CMC), 아크릴로니트릴스타이렌부타디엔 공중합체 (Acrylonitrile-styrene-butadiene copolymer), 폴리이미드(Polyimide, PI) 등이 있으며, 이들은 단독으로 사용되거나 2종 이상을 혼합하여 사용될 수 있다. 구체적으로, 폴리비닐리덴 플루오라이드-헥사플루오로프로필렌 코폴리머를 사용할 수 있다. 상기 폴리비닐리덴 플루오라이드-헥사플루오로프로필렌 코폴리머는 중량 평균 분자량이 800,000 g/mol 이하일 수 있으며, 구체적으로 600,000 g/mol 내지 800,000 g/mol 일 수 있다. 상기 분자량 범위 내에서, 분리막의 전해질 함침성이 우수하여 전기력 출력이 효율적으로 일어나는 전지를 생산할 수 있는 이점이 있다. 본 발명의 일 예에 따른 폴리비닐리덴 플루오라이드- 헥사플루오로프로필렌 코폴리머에 있어서, 플리비닐리덴 플루오라이드 및 헥사플루오로프로필렌의 각각의 함량은 특별히 제한되지 아니하나, 예를 들어, 코폴리머의 총 중량을 기준으로 헥사플루오로프로필렌이 0.1 내지 40 중량%로 함유될 수 있다.The organic binder included in the first coating layer is not particularly limited as long as it is a component that does not readily dissolve in the electrolyte while having adhesion to the electrode. For example, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-trichloroethylene (Polyvinylidene fluoride-) trichlorethylene, PVdF-TCE), polyvinylidene fluoride-chlorotrifluoroethylene copolymer (PVFF-CTFE), polymethylmethacrylate (PMMA), polyacrylonitrile, PAN), Polyvinylpyrrolidone (PVP), Polyvinyl Acetate (PVA), Polyethylene Oxide (PEO), Ethylene-vinyl acetate copolymer, Cellulose Acetate Cellulose acetate (CA), Cellulose acetate butyrate (CAB), Cellulose Tate propionate (Cellulose acetate propionate, CAP), cyanoethyl pullulan (CyEPL), cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, Pullulan, carboxymethyl cellulose (CMC), acrylonitrile-styrene-butadiene copolymer, polyimide (PI), etc., which are used alone. Or a mixture of two or more thereof. Specifically, polyvinylidene fluoride-hexafluoropropylene copolymer can be used. The polyvinylidene fluoride-hexafluoropropylene copolymer may have a weight average molecular weight of 800,000 g / mol or less, and specifically 600,000 g / mol to 800,000 g / mol. Within the molecular weight range, there is an advantage in that the battery can be produced in which the electric force output is efficiently due to the electrolyte impregnation of the separator. In the polyvinylidene fluoride-hexafluoropropylene copolymer according to an embodiment of the present invention, the content of each of the polyvinylidene fluoride and the hexafluoropropylene is not particularly limited, but for example, Hexafluoropropylene may be contained in an amount of 0.1 to 40% by weight based on the total weight.

본 발명의 또 다른 일 예에 따르면, 제1 코팅층에 포함되는 유기 바인더로서 폴리비닐리덴 플루오라이드-헥사플루오로프로필렌 코폴리머와 폴리비닐리덴 플루오라이드 호모폴리머를 혼합하여 사용할 수 있다. 상기 폴리비닐리덴 플루오라이드 호모폴리머는 중량 평균 분자량이 1,000,000 g/mol 이상인 것을 사용할 수 있으며, 구체적으로, 1,000,000 g/mol 내지 1,200,000 g/mol 인 것을 사용할 수 있다. 상기 분자량 범위 내에서 코팅층과 폴리올레핀계 기재 필름 사이의 접착력이 강화되어 열에 의한 수축을 줄일 수 있고, 코팅층과 전극 사이의 접착력 또한 우수하여 양극과 음극의 단락을 효과적으로 억제할 수 있다. 또한, 상기 분자량 범위 내에서 폴리비닐리덴 플루오라이드 호모폴리머가 용매에 원활히 용해되어 과량의 고비점 용매가 필요하지 않아 건조시 발생할 수 있는 공정 불량 문제를 방지할 수 있다.According to another example of the present invention, a polyvinylidene fluoride-hexafluoropropylene copolymer and a polyvinylidene fluoride homopolymer may be used as an organic binder included in the first coating layer. The polyvinylidene fluoride homopolymer may be used having a weight average molecular weight of 1,000,000 g / mol or more, specifically, it may be used from 1,000,000 g / mol to 1,200,000 g / mol. Within the molecular weight range, the adhesion between the coating layer and the polyolefin-based substrate film is enhanced to reduce shrinkage due to heat, and the adhesion between the coating layer and the electrode is also excellent, thereby effectively suppressing a short circuit between the anode and the cathode. In addition, the polyvinylidene fluoride homopolymer is smoothly dissolved in a solvent within the above molecular weight range so that an excessive high boiling point solvent is not required, thereby preventing a process defect problem that may occur during drying.

본 발명의 일 예에 따르면, 제1 코팅층100 중량부에 대하여, 유기 바인더는 5 내지 50 중량부로 함유될 수 있고, 예를 들어 10 내지 30 중량부로 함유될 수 있다. 상기 범위 내에서 코팅층의 형성력 및 접착력이 우수한 이점이 있다.According to one embodiment of the present invention, with respect to 100 parts by weight of the first coating layer, the organic binder may be contained in 5 to 50 parts by weight, for example 10 to 30 parts by weight. Within the above range, the forming force and the adhesive force of the coating layer are excellent.

제2 코팅층Second coating layer

제2 코팅층은 유기 바인더를 함유하며, 전기 화학 전지에 적용시 전지의 음극에 접착되는 분리막 일면에 형성된다. 제2 코팅층에 포함되는 유기 바인더는 제1 코팅층의 유기 바인더와 상이할 수 있다. 제2 코팅층에 포함되는 유기 바인더로는 예를 들어, 스타이렌-부타디엔 고무(Styrene butadiene rubber, SBR), 카르복시 메틸 셀룰로오스 (Carboxy methyl cellulose, CMC), 폴리 부틸 아크릴 레이트(PolyButyl MethAcrylate, PBMA), 에틸렌 바이닐 아세테이트(Ethylene Vinyl Acrylate, EVA) 등을 들 수 있다. 이들은 단독으로 사용되거나 2 종 이상을 혼합하여 사용될 수 있으며, 예를 들어, 스타이렌-부타디엔 고무를 사용할 수 있다. The second coating layer contains an organic binder and is formed on one surface of the separator that is adhered to the negative electrode of the battery when applied to the electrochemical cell. The organic binder included in the second coating layer may be different from the organic binder of the first coating layer. As the organic binder included in the second coating layer, for example, styrene-butadiene rubber (SBR), carboxy methyl cellulose (CMC), polybutyl acrylate (PBMA), ethylene Vinyl acetate (Ethylene Vinyl Acrylate, EVA) and the like. These may be used alone or in combination of two or more thereof, for example, styrene-butadiene rubber may be used.

본 발명의 또 다른 일 예에 따르면, 제2 코팅층에 유기 바인더로 스타이렌-부타디엔 고무를 포함하여 사용할 때에는 카르복시 메틸 셀룰로오스를 함께 사용할 수 있다. 스타이렌-부타디엔 고무는 수계 (水系) 바인더이기 때문에 단독으로 사용하는 경우 코팅제의 점성이 약해질 수 있으므로, 접착력을 추가로 부여하는 카르복시 메틸 셀룰로오스를 함께 사용하면 코팅제의 점성을 높일 수 있는 이점이 있다.According to another example of the present invention, when the styrene-butadiene rubber is used as the organic binder in the second coating layer, carboxymethyl cellulose may be used together. Since styrene-butadiene rubber is an aqueous binder, when used alone, the viscosity of the coating agent may be weakened. Therefore, the use of carboxy methyl cellulose, which additionally imparts adhesion, may increase the viscosity of the coating agent. .

또한, 상기 제2 코팅층은 필요에 따라 무기 입자를 함유할 수 있으며, 상기 제1 코팅층과 동일하거나 상이한 무기 입자를 사용할 수 있다. 상기 무기 입자는 제2 코팅층 100 중량부에 대하여 50 내지 95 중량부, 구체적으로 70 내지 90 중량부로 포함될 수 있다.  In addition, the second coating layer may contain inorganic particles as needed, and may use the same or different inorganic particles as the first coating layer. The inorganic particles may be included in an amount of 50 to 95 parts by weight, specifically 70 to 90 parts by weight, based on 100 parts by weight of the second coating layer.

본 발명의 일 예에 따르면, 제2 코팅층과 전지의 음극과의 접착력은 20 gf/cm 이상일 수 있으며, 예를 들어, 20 gf/cm 내지 50 gf/cm 일 수 있다. 상기 범위 내에서, 코팅층과 전극이 충분히 강하게 접착되어 양극과 음극의 단락을 방지할 수 있다. 또한, 이를 고출력 대용량 전지의 제조에 활용하는 경우, 전지의 안전성을 향상시켜 전지의 수명을 보다 장기화할 수 있는 이점이 있다. According to an example of the present invention, the adhesion between the second coating layer and the negative electrode of the battery may be 20 gf / cm or more, for example, 20 gf / cm to 50 gf / cm. Within this range, the coating layer and the electrode may be sufficiently strongly bonded to prevent short circuit between the positive electrode and the negative electrode. In addition, in the case of using this for the manufacture of high-output large-capacity battery, there is an advantage that can improve the battery safety to extend the life of the battery more.

상기 전지는 양극, 음극 및 분리막을 포함하며 전해질로 채워진 전기 화학 전지를 말하며, 상기 전지 및 전지의 전극 등에 관한 상세한 설명은 후술하는 내용에 갈음한다.The battery refers to an electrochemical cell filled with an electrolyte including a positive electrode, a negative electrode, and a separator, and detailed descriptions of the battery, the electrode of the battery, and the like will be replaced with the following description.

본 발명의 또 다른 일 예에 따르면, 상기 전지에 포함된 상기 분리막의 제2 코팅층은 전지의 음극과의 접착력이 20 gf/cm 이상일 수 있다. 상기 제2 코팅층과 전극 간의 접착력을 측정하는 방법은 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 통상적으로 사용하는 방법을 사용할 수 있다.According to another example of the present invention, the second coating layer of the separator included in the battery may have an adhesive strength of about 20 gf / cm or more with the negative electrode of the battery. The method for measuring the adhesive force between the second coating layer and the electrode is not particularly limited, and a method commonly used in the art may be used.

상기 제2 코팅층과 전극 간의 접착력을 측정하는 방법의 비제한적인 예는 다음과 같다: 제조된 분리막을 양 전극 사이에 위치시키고 접착시켜 양극/분리막/음극 형태로 제조한 다음, 이를 알루미늄 파우치 (pouch)에 삽입한다. 그 다음, 이에 전해액을 주액하고 상기 알루미늄 파우치를 밀봉하여 단판 셀 (cell)을 제작한다. 이를 50 ℃, 100 kgf/cm2, 20초의 조건으로 압력을 가하여 12 시간 방치 후, 상기 단판 셀을 해체하여 서로 접착되어 있는 양극/분리막/음극을 가로(MD) 약 2.5 cm × 세로(TD) 약 7 cm로 재단하고 이를 유리판 위에 투명 양면 테이프 (3M)를 이용하여 단단히 부착시킨 다음, 인장 강도 측정기 (UTM; Universal Test Machine)를 이용하여 코팅층과 전극간의 접착력을 측정할 수 있다.A non-limiting example of a method for measuring the adhesion between the second coating layer and the electrode is as follows: the prepared separator is placed between the positive electrode and bonded to prepare a positive electrode / separator / cathode form, and then aluminum pouch (pouch) ). Then, the electrolyte solution is poured into it and the aluminum pouch is sealed to prepare a single cell. After leaving it for 12 hours under pressure at 50 ° C., 100 kgf / cm 2 , and 20 seconds, the single cell was disassembled and the anode / separator / cathode adhered to each other (MD) about 2.5 cm × length (TD). After cutting to about 7 cm and firmly attached to the glass plate using a transparent double-sided tape (3M), a tensile strength meter (UTM; Universal Test Machine) can be used to measure the adhesion between the coating layer and the electrode.

본 발명의 또 다른 일 예에 따르면, 상기 분리막의 박리력은 300 gf/cm 이상일 수 있으며, 구체적으로 300 내지 800 gf/ cm일 수 있다. 상기 범위 내에서 전지 과열시 발생할 수 있는 코팅층과 기재 필름 간의 분리를 방지할 수 있어, 전극의 단락을 방지 및 열적 안정성을 향상시키는 효과를 얻을 수 있다.According to another example of the present invention, the separation force of the separator may be 300 gf / cm or more, specifically 300 to 800 gf / cm. Within this range, it is possible to prevent separation between the coating layer and the base film which may occur when the battery is overheated, thereby preventing the short circuit of the electrode and improving the thermal stability.

상기 분리막의 박리력을 측정하는 방법은 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 통상적으로 사용하는 방법을 사용할 수 있다. 상기 박리력을 측정하는 방법의 비제한적인 예는 다음과 같다: 제조된 분리막을 가로(MD) 2.5 cm × 세로(TD) 7 cm로 재단하여 각각 10개씩의 시료를 준비한다. 상기 각 시료를 유리판 위에 투명 양면 테이프(3M)를 이용하여 단단히 부착시킨 다음, 인장 강도 측정기 (UTM; Universal Test Machine)를 이용하여 상기 각 분리막이 박리되는 데에 필요한 힘을 측정하고 그 평균값을 계산하는 방식으로 수행될 수 있다.Method for measuring the peel force of the separator is not particularly limited, it can be used a method commonly used in the art. A non-limiting example of the method for measuring the peel force is as follows: The prepared separator is cut to 2.5 cm x 7 cm (TD) to prepare 10 samples each. Each sample was firmly attached to the glass plate using a transparent double-sided tape (3M), and then the force required to peel each separator was calculated using a universal test machine (UTM) and the average value thereof was calculated. It can be done in a way.

본 발명의 또 다른 일 예에 따르면, 상기 분리막은 120 ℃에서 1 시간 동안 방치한 후의 열수축률이 종 방향 (MD) 및 횡 방향 (TD)으로 각각 7 % 이하일 수 있으며, 예를 들어, 6 % 이하일 수 있고, 구체적으로 종 방향 또는 횡 방향 중 어느 하나 이상의 방향으로 5 % 이하일 수 있다. 상기 범위 내에서, 전극의 단락을 효과적으로 방지하여 전지의 안전성을 향상시키는 이점이 있다.According to another example of the present invention, the separator may have a thermal contraction rate of 7% or less in the longitudinal direction (MD) and the transverse direction (TD) after being left at 120 ° C. for 1 hour, for example, 6% It may be less than, specifically 5% or less in the direction of any one of the longitudinal or transverse direction. Within this range, there is an advantage of effectively preventing a short circuit of the electrode to improve the safety of the battery.

상기 분리막의 열수축률을 측정하는 방법은 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 통상적으로 사용하는 방법을 사용할 수 있다. 분리막의 열수축률을 측정하는 방법의 비제한적인 예는 다음과 같다: 제조된 분리막을 가로(MD) 약 5 cm × 세로(TD) 약 5 cm 크기로 재단하고, 이를 120 ℃의 챔버 (chamber)에서 1시간 동안 보관한 다음, 상기 분리막의 MD 방향 및 TD 방향의 수축 정도를 측정하여 열수축률을 계산하는 방식으로 수행될 수 있다.The method for measuring the thermal contraction rate of the separator is not particularly limited, it can be used a method commonly used in the art. A non-limiting example of a method for measuring the thermal contraction rate of the separator is as follows: The prepared separator is cut to about 5 cm in width (MD) x 5 cm in length (TD), which is a chamber at 120 ° C. After storing for 1 hour, the shrinkage in the MD direction and the TD direction of the separator can be measured by calculating the heat shrinkage rate.

이하, 본 발명의 실시예들에 따른 분리막을 제조하는 방법에 대해 구체적으로 설명한다. 우선, 유기 바인더를 제1 용매에 첨가하고 교반하여 고분자 용액을 제조하고, 상기 고분자 용액과 별도로 무기입자를 제2 용매에 첨가하고 분산시켜 무기 분산액을 제조한다. 이 때, 무기입자의 분산을 위해 비즈밀을 이용하여 밀링할 수 있다. 상기 제1 용매 및 제2 용매로 아세톤(acetone), 테트라하이드로퓨란(tetrahydrofuran), 메틸렌클로라이드(methylene chloride), 클로로포름(chloroform), 메틸포름아미드(dimethylformamide), N-메틸-2-피롤리돈(N-methyl-2-pyrrolidone, NMP), 시클로헥산(cyclohexane) 및 물로 이루어진 그룹으로 선택된 단독 또는 이들의 혼합물을 사용할 수 있으나, 이에 제한되는 것은 아니다. Hereinafter, a method of manufacturing a separator according to embodiments of the present invention will be described in detail. First, an organic binder is added to the first solvent and stirred to prepare a polymer solution, and separately from the polymer solution, inorganic particles are added to the second solvent and dispersed to prepare an inorganic dispersion. At this time, it can be milled using a bead mill for the dispersion of the inorganic particles. Acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone as the first solvent and the second solvent N-methyl-2-pyrrolidone, NMP), cyclohexane (cyclohexane) and water selected from the group consisting of, or a mixture thereof may be used, but is not limited thereto.

이어서, 상기 고분자 용액, 무기 분산액 및 제3 용매를 일정 비율로 혼합하여 코팅액을 제조하고, 상기 코팅액으로 기재 필름 상에 코팅층을 형성할 수 있다. 상기 제1 내지 제3 용매는 동일할 수 있으며, 예를 들어 아세톤을 사용할 수 있다. 고분자 용액과 무기 분산액을 별도로 제조하지 않고 당업자의 선택에 따라 유기 바인더와 무기 입자를 제1 용매에 첨가하고 교반하여 코팅액을 제조할 수도 있다. 고분자 용액과 무기 분산액을 별도로 제조하는 경우 무기 입자의 분산성 및 조액 안정성이 우수해질 수 있다. 기재 필름에 코팅층을 형성하는 방법은 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 통상적으로 사용하는 방법을 사용할 수 있다. 예를 들어, 딥(Dip) 코팅법, 다이(Die) 코팅법, 롤(Roll) 코팅법 또는 콤마(Comma) 코팅법 등을 들 수 있으며, 이들은 단독 또는 2 가지 이상의 방법을 혼합하여 적용될 수 있다. 본 발명의 일 예에 따른 비대칭성 코팅층이 형성된 다공성 분리막을 제조하는 비제한적인 예는 다음과 같다 : 두께 9 ㎛의 폴리에틸렌 기재 필름 (Celgard PE) 중 전지의 양극에 접하는 면에 하기의 제1 코팅제를 도포하여 다이(die) 코팅 방식으로 코팅한 후 제1 코팅층을 형성하고, 상기 기재 필름 중 전지의 음극에 접하는 면에 하기의 제2 코팅제를 도포하여 다이(die) 코팅 방식으로 코팅한 후 건조하여 제2 코팅층을 형성하여, 양면에 비대칭성 코팅층이 형성된 다공성 분리막을 제조할 수 있다.Subsequently, the polymer solution, the inorganic dispersion and the third solvent may be mixed in a predetermined ratio to prepare a coating solution, and the coating solution may be used to form a coating layer on the base film. The first to third solvents may be the same, for example, acetone may be used. Instead of separately preparing a polymer solution and an inorganic dispersion, a coating solution may be prepared by adding and stirring the organic binder and the inorganic particles to the first solvent according to a choice by those skilled in the art. When the polymer solution and the inorganic dispersion are separately prepared, the dispersibility and crude liquid stability of the inorganic particles may be excellent. The method of forming the coating layer on the base film is not particularly limited, and a method commonly used in the art may be used. For example, a dip coating method, a die coating method, a roll coating method, or a comma coating method may be used, and these may be applied alone or by mixing two or more methods. . A non-limiting example of preparing a porous separator having an asymmetric coating layer according to an embodiment of the present invention is as follows: A first coating agent on a surface of the polyethylene base film (Celgard PE) having a thickness of 9 μm in contact with the positive electrode of the battery; Coated with a die coating method to form a first coating layer, and then coated with a die coating method to apply a second coating agent to a surface of the base film in contact with the negative electrode of the battery, followed by drying. By forming a second coating layer, it is possible to manufacture a porous separator having an asymmetric coating layer formed on both sides.

본 발명의 또 다른 일 예에 따르면, 상기 코팅층을 포함하는 다공성 분리막, 극 및 음극을 포함하며 전해질로 채워진 전기 화학 전지를 제공한다.According to another embodiment of the present invention, an electrochemical cell including a porous separator, a pole, and a cathode including the coating layer and filled with an electrolyte is provided.

상기 전기 화학 전지의 종류는 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 알려진 종류의 전지일 수 있다. 본 발명의 일 예에 따른 상기 전기 화학 전지는 예를 들어, 리튬 금속 이차 전지, 리튬 이온 이차 전지, 리튬 폴리머 이차 전지 또는 리튬 이온 폴리머 이차 전지 등과 같은 리튬 이차 전지일 수 있다.The kind of the electrochemical cell is not particularly limited, and may be a battery of a kind known in the art. The electrochemical battery according to an embodiment of the present invention may be, for example, a lithium secondary battery such as a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.

본 발명의 일 예에 따른 전기 화학 전지를 제조하는 방법은 특별히 제한되지 아니하며, 본 발명의 일 예에 따른 기술 분야에서 통상적으로 사용하는 방법을 사용할 수 있다. 상기 전기 화학 전지를 제조하는 방법의 비제한적인 예는 다음과 같다: 본 발명의 일 예에 따른 상기 유기 및 무기 혼합물 코팅층을 포함하는 분리막을, 전지의 양극과 음극 사이에 위치시킨 후, 이에 전해액을 채우는 방식으로 전지를 제조할 수 있다.The method for manufacturing the electrochemical cell according to an example of the present invention is not particularly limited, and a method commonly used in the art according to an example of the present invention may be used. A non-limiting example of a method of manufacturing the electrochemical cell is as follows: A separator comprising the organic and inorganic mixture coating layer according to an example of the present invention is placed between the positive electrode and the negative electrode of the cell, and then the electrolyte solution. The battery can be prepared by filling in the following manner.

본 발명의 일 예에 따른 전기 화학 전지를 구성하는 전극은, 본 발명의 기술 분야에서 통상적으로 사용하는 방법에 의해 전극 활물질을 전극 전류집전체에 결착된 형태로 제조할 수 있다.The electrode constituting the electrochemical cell according to an embodiment of the present invention may be manufactured in a form in which an electrode active material is bound to an electrode current collector by a method commonly used in the technical field of the present invention.

본 발명의 일 예에 따른 전극 활물질 중 양극 활물질은 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 통상적으로 사용하는 양극 활물질을 사용할 수 있다. 구체적으로, 상기 양극은 리튬 이온을 가역적으로 삽입 및 탈리할 수 있는 양극 활물질을 포함하며, 이러한 양극 활물질로는 코발트, 망간, 니켈에서 선택되는 최소한 1종 및 리튬과의 복합 금속 산화물인 것일 수 있다. 금속 사이의 고용율은 다양하게 이루어질 수 있으며, 이들 금속 외에 Mg, Al, Co, Ni, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V 및 희토류 원소로 이루어진 군에서 선택되는 원소가 더 포함될 수 있다. 상기 양극은 예를 들어, 리튬과 Co, Ni, Mn, Al, Si, Ti 및 Fe로 이루어진 군에서 선택되는 금속의 복합 금속 산화물일 수 있으며, 구체적으로 리튬 코발트 옥사이드 (lithium cobalt oxide, LCO. 예를 들어 LiCoO2), 리튬 니켈 코발트 망간 옥사이드 (lithium nickel manganese cobalt oxide, NCM. 예를 들어 Li[Ni(x)Co(y)Mn(z)]O2), 리튬 망간 옥사이드 (Lithium manganese oxide, LMO. 예를 들어 LiMn2O4, LiMnO2), 리튬 아이언 포스페이트 (Lithium Iron phosphate, LFP. 예를 들어 LiFePO4), 리튬 니켈 옥사이드 (LNO, 예를 들어 LiNiO2) 등을 사용할 수 있다.The cathode active material of the electrode active material according to an embodiment of the present invention is not particularly limited, and a cathode active material commonly used in the technical field of the present invention may be used. Specifically, the positive electrode includes a positive electrode active material capable of reversibly inserting and detaching lithium ions, and the positive electrode active material may be at least one selected from cobalt, manganese, nickel, and a composite metal oxide with lithium. . The solid solution ratio between the metals may be various, and in addition to these metals, Mg, Al, Co, Ni, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, An element selected from the group consisting of Fe, Sr, V, and rare earth elements may be further included. The anode may be, for example, a composite metal oxide of a metal selected from the group consisting of lithium and Co, Ni, Mn, Al, Si, Ti, and Fe, and specifically, lithium cobalt oxide (LCO.) For example LiCoO 2 ), lithium nickel manganese cobalt oxide, NCM. For example Li [Ni (x) Co (y) Mn (z)] O 2 ), lithium manganese oxide (Lithium manganese oxide, LMO, for example LiMn 2 O 4, LiMnO 2 ), lithium iron phosphate (LFP. For example LiFePO 4 ), lithium nickel oxide (LNO, for example LiNiO 2 ) and the like.

상기 음극은 리튬 이온을 삽입 및 탈리할 수 있는 음극 활물질을 포함하며, 이러한 음극 활물질로는 결정질 또는 비정질의 탄소, 또는 탄소 복합체의 탄소계 음극 활물질 (열적으로 분해된 탄소, 코크, 흑연), 연소된 유기 중합체 화합물, 탄소 섬유, 산화 주석 화합물, 리튬 금속 또는 리튬과 다른 원소의 합금을 사용할 수 있다. 예를 들면 비결정질 탄소로는 하드 카본, 코크스, 1,500 ℃이하에서 소성한 메조카본 마이크로 비드 (mesocarbon microbead, MCMB), 메조페이스피치계 탄소섬유 (mesophase pitch-based carbon fiber, MPCF)등이 있다. 결정질 탄소로는 흑연계 재료가 있으며, 구체적으로는 천연 흑연, 흑연화 코크스, 흑연화 MCMB, 흑연화 MPCF 등이 있다. 상기 음극은 예를 들어, 결정질 또는 비정질의 탄소를 포함할 수 있다. The negative electrode includes a negative electrode active material capable of inserting and desorbing lithium ions, and the negative electrode active material includes crystalline or amorphous carbon, or a carbon-based negative electrode active material (thermally decomposed carbon, coke, graphite) and combustion of a carbon composite. Organic polymer compounds, carbon fibers, tin oxide compounds, lithium metal or alloys of lithium and other elements can be used. For example, amorphous carbons include hard carbon, coke, mesocarbon microbeads (MCMB) fired at 1,500 ° C or lower, and mesophase pitch-based carbon fibers (MPCF). The crystalline carbon includes a graphite material, and specific examples thereof include natural graphite, graphitized coke, graphitized MCMB, graphitized MPCF, and the like. The negative electrode may include, for example, crystalline or amorphous carbon.

상기 양극 또는 음극은 전극 활물질 외에 결합제 및 도전재, 필요한 경우 증점제를 용매에 분산시켜 전극 슬러리 조성물을 제조하고, 이 슬러리 조성물을 전극 집전체에 도포하여 제조될 수 있다. 상기 결합제, 도전재 및 증점제는 본 발명의 기술분야에서 통상적으로 사용하는 것을 사용할 수 있다. 예를 들어, 결합제로서, 폴리비닐리덴-플루오라이드(Polyvinylidene-fluoride, PVdF), 스타이렌-부타디엔 고무(styrene-butadiene rubber, SBR) 등이 있고, 도전재로서, 카본 블랙, 증점제로서 카보네이트 메틸 셀룰로오스(Carbonate methyl cellulose, CMC)를 사용할 수 있다.The positive electrode or the negative electrode may be prepared by dispersing a binder, a conductive material, and, if necessary, a thickener in a solvent in addition to an electrode active material to prepare an electrode slurry composition, and applying the slurry composition to an electrode current collector. The binder, the conductive material and the thickener may be used as commonly used in the art. For example, as the binder, polyvinylidene-fluoride (PVdF), styrene-butadiene rubber (SBR), and the like, carbon black as a conductive material, and carbonate methyl cellulose as a thickener (Carbonate methyl cellulose, CMC) can be used.

본 발명의 일 예에 따른 전극 전류 집전체는 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 통상적으로 사용하는 전극 전류 집전체를 사용할 수 있다. 상기 전극 전류 집전체 중 양극 전류 집전체 소재의 비제한적인 예로는, 알루미늄, 니켈 또는 이들의 조합에 의하여 제조되는 호일 등을 들 수 있다. 상기 전극 전류 집전체 중 음극 전류 집전체 소재의 비제한적인 예로는, 구리, 금, 니켈, 구리 합금 또는 이들의 조합에 의하여 제조되는 호일 등을 들 수 있다. The electrode current collector according to an embodiment of the present invention is not particularly limited, and an electrode current collector commonly used in the art may be used. Non-limiting examples of the positive electrode current collector material of the electrode current collector may be a foil made of aluminum, nickel or a combination thereof. Non-limiting examples of the negative electrode current collector material of the electrode current collector may be a foil produced by copper, gold, nickel, a copper alloy or a combination thereof.

또한, 상기 양극 집전체 및 음극 집전체의 형태로는 포일이나 메시 형태를 들 수 있다.The positive electrode current collector and the negative electrode current collector may be in the form of a foil or a mesh.

본 발명의 일 예에 따른 전해액은 특별히 제한되지 아니하며, 본 발명의 기술 분야에서 통상적으로 사용하는 전기 화학 전지용 전해액을 사용할 수 있다. 상기 전해액은 A+ B-와 같은 구조의 염이, 유기 용매에 용해 또는 해리된 것일 수 있다.The electrolyte solution according to an embodiment of the present invention is not particularly limited, and an electrolyte solution for an electrochemical cell commonly used in the art may be used. The electrolyte solution may be one in which a salt having a structure such as A + B − is dissolved or dissociated in an organic solvent.

상기 A+의 비제한적인 예로는, Li+, Na+ 또는 K+와 같은 알칼리 금속 양이온, 또는 이들의 조합으로 이루어진 양이온을 들 수 있다. Non-limiting examples of A + include a cation consisting of an alkali metal cation such as Li + , Na + or K + , or a combination thereof.

상기 B-의 비제한적인 예로는, PF6 -, BF4 -, Cl-, Br-, I-, ClO4 -, AsF6 -, CH3CO2 -, CF3SO3 -, N (CF3SO2)2 - 또는 C (CF2SO2)3 -와 같은 음이온, 또는 이들의 조합으로 이루어진 음이온을 들 수 있다.The B - Non-limiting examples of the, PF 6 -, BF 4 - , Cl -, Br -, I -, ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 - or C (CF 2 SO 2) 3 - anions, such as, or may be an anion consisting of a combination thereof.

상기 유기 용매의 비제한적인 예로는, 프로필렌 카보네이트 (Propylene carbonate; PC), 에틸렌 카보네이트 (Ethylene carbonate, EC), 디에틸카보네이트 (Diethyl carbonate; DEC), 디메틸카보네이트 (Dimethyl carbonate, DMC), 디메틸포름아마이드 (Dimethylformamide, DMF), 디프로필카보네이트 (Dipropyl carbonate, DPC), 디메틸설폭사이드(Dimethyl sulfoxide, DMSO), 아세토니트릴 (Acetonitrile), 디메톡시에탄(dimethoxyethane), 디에톡시에탄(diethoxyethane), 테트라하이드로푸란 (Tetrahydrofuran), N-메틸-2-피롤리돈 (N-methyl-2-pyrrolidone, NMP), 에틸메틸카보네이트 (Ethyl methyl carbonate, EMC) 또는 감마-부티롤락톤 ( -Butyrolactone) 등을 들 수 있다. 이들은 단독으로 사용되거나 2 종 이상을 혼합하여 사용될 수 있다.Non-limiting examples of the organic solvent include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dimethylformamide (Dimethylformamide, DMF), Dipropyl carbonate (DPC), Dimethyl sulfoxide (DMSO), Acetonitrile, Dimethoxyethane, Diethoxyethane, Tetrahydrofuran ( Tetrahydrofuran), N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC) or gamma-butyrolactone (-Butyrolactone), and the like. These may be used alone or in combination of two or more thereof.

이하, 실시예, 비교예 및 실험예들을 통하여 본 발명을 보다 상세히 설명한다. 다만, 이들 실시예, 비교예 및 실험예들은 본 발명을 예시적으로 설명하기 위한 것에 불과하며, 따라서 본 발명의 범위가 이들에 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Experimental Examples. However, these Examples, Comparative Examples and Experimental Examples are only for illustrating the present invention by way of example, and thus the scope of the present invention is not limited thereto.

실시예 1Example 1

제1 코팅제의 제조Preparation of First Coating

상기 제1 코팅제를 제조하기 위하여, 중량 평균 분자량이 70만 g/mol인 폴리비닐리덴 플루오라이드-헥사플루오로프로필렌 코폴리머 (21216, 솔베이 사)를 아세톤 (대정화금 사)에 10 중량%로 첨가하고 교반기에서 4시간 동안 25 ℃의 온도 조건에서 교반하여 제1 고분자 용액을 제조하였다. To prepare the first coating agent, a polyvinylidene fluoride-hexafluoropropylene copolymer (21216, Solvay Co., Ltd.) having a weight average molecular weight of 700,000 g / mol was added to acetone (coarse gold) by 10 wt%. The first polymer solution was prepared by adding and stirring in a stirrer at a temperature of 25 ° C. for 4 hours.

상기 제1 고분자 용액과 별도로, Al2O3를 (LS235, 일본 경금속 사) 아세톤에 25 중량%로 첨가하고 비즈밀을 이용하여 25 ℃에서 2 시간 동안 밀링하여 분산시켜 무기 분산액을 제조하였다.Separately from the first polymer solution, Al 2 O 3 (LS235, Nippon Light Metal Co., Ltd.) was added to 25% by weight of acetone and milled and dispersed at 25 ° C. for 2 hours using a bead mill to prepare an inorganic dispersion.

그 다음, 상기 제1 고분자 용액, 무기 분산액 및 아세톤 (대정화금 사)을 제1 고분자 용액:무기 분산액:아세톤 = 1:1:3의 중량비로 혼합하고 파워 믹서로 25℃에서 2 시간 동안 교반하여 제1 코팅제를 제조하였다.Next, the first polymer solution, the inorganic dispersion and the acetone (a large purified gold company) were mixed in a weight ratio of the first polymer solution: inorganic dispersion: acetone = 1: 1: 3 and stirred at 25 ° C. for 2 hours with a power mixer. To prepare a first coating agent.

제2 코팅제의 제조Preparation of Second Coating

상기 제2 코팅제를 제조하기 위하여, 스타이렌-부타디엔 고무 (STYRON 사)를 물에 10 중량%로 첨가하고 교반기에서 4시간 동안 25℃의 온도 조건에서 교반하여 고분자 용액을 제조하고, 상기 고분자 용액, 카르복시 메틸 셀룰로오스 (CMC, 워솔케이제이티 사) 및 아세톤 (대정화금 사)을 고분자 용액:CMC:아세톤 = 1:3:6의 중량비로 혼합하고 파워 믹서로 25 ℃에서 2 시간 동안 교반하여 제2 코팅제를 제조하였다.In order to prepare the second coating agent, styrene-butadiene rubber (STYRON Co.) is added to 10% by weight of water and stirred for 4 hours at a temperature condition of 25 ℃ in a stirrer to prepare a polymer solution, the polymer solution, Carboxymethyl cellulose (CMC, WASOLKAZeti Co., Ltd.) and acetone (Crystal Gold Co., Ltd.) were mixed in a weight ratio of polymer solution: CMC: acetone = 1: 3: 6 and stirred for 2 hours at 25 ° C. with a power mixer to obtain a second mixture. A coating was prepared.

코팅층 형성 및 분리막의 제조Coating layer formation and preparation of separator

두께 9 ㎛의 폴리에틸렌 기재 필름 (Celgard PE) 중 전지의 양극에 접하는 면에 하기의 제1 코팅제를 도포하여 다이(die) 코팅 방식으로 코팅한 후 제1 코팅층을 형성하고, 상기 기재 필름 중 전지의 음극에 접하는 면에 하기의 제2 코팅제를 도포하여 다이(die) 코팅 방식으로 코팅한 후 건조하여 제2 코팅층을 형성하여, 양면에 비대칭성 코팅층이 형성된 다공성 분리막을 제조하였다. In the polyethylene base film (Celgard PE) having a thickness of 9 μm, the following first coating agent is coated on the surface of the battery in contact with the positive electrode of the battery, and then coated by a die coating method to form a first coating layer. The second coating agent was coated on the surface in contact with the cathode, coated with a die coating method, and then dried to form a second coating layer, thereby preparing a porous separator having an asymmetric coating layer formed on both surfaces thereof.

실시예 2Example 2

상기 실시예 1에 있어서, 상기 제1 코팅제 제조시의 상기 제1 고분자 용액에 추가적으로, 중량 평균 분자량이 110만 g/mol인 폴리비닐리덴 플루오라이드 호모폴리머(5130, 솔베이 사)를 DMF(대정화금 사)에 10 중량%로 첨가하고 교반기에서 4시간 동안 25℃의 온도 조건에서 교반하여 제2 고분자 용액을 제조하였다. 상기 제2 고분자 용액을 사용하며, 상기 제1 고분자 용액:제2 고분자 용액:무기 분산액:아세톤 = 1:1:3:6의 중량비로 혼합하고 파워 믹서로 25 ℃에서 2 시간 동안 교반하여 사용하였다.In Example 1, a polyvinylidene fluoride homopolymer (5130, Solvay Co., Ltd.) having a weight average molecular weight of 1.1 million g / mol was further added to the first polymer solution in preparing the first coating agent. 10% by weight of gold) and stirred in a stirrer at a temperature of 25 ℃ for 4 hours to prepare a second polymer solution. The second polymer solution was used. The first polymer solution: second polymer solution: inorganic dispersion: acetone = 1: 1: 3: 6 was mixed in a weight ratio, and stirred at 25 ° C. for 2 hours with a power mixer. .

상기 제2 코팅제로, 폴리 부틸 메타 아크릴레이트(Aldrich사)를 아세톤에 10 중량%로 첨가하고 교반기에서 2시간 동안 40 ℃의 온도 조건에서 교반하여 제조한 고분자 용액을 사용하고 고분자 용액:아세톤 = 7:3의 중량비로 혼합하고 파워 믹서로 25 ℃에서 2 시간 동안 교반하여 사용한 것을 제외하고는 상기 실시예 1과 동일한 방법에 따라 분리막을 제조하였다.As the second coating agent, a polymer solution prepared by adding polybutyl methacrylate (Aldrich) to acetone at 10 wt% and stirring at a temperature condition of 40 ° C. for 2 hours in a stirrer was used. A separator was prepared in the same manner as in Example 1, except that the mixture was mixed at a weight ratio of 3: 3 and stirred at 25 ° C. for 2 hours with a power mixer.

실시예 3Example 3

상기 실시예 2에 있어서, 상기 제2 코팅제로, 에틸렌 바이닐 아세테이트 (한화 케미컬사)를 물에 10 중량%로 첨가하고 교반기에서 2시간 동안 40 ℃의 온도 조건에서 교반하여 제조한 고분자 용액을 사용하고 고분자 용액:아세톤 = 7:3의 중량비로 혼합하고 파워 믹서로 25 ℃에서 2 시간 동안 교반하여 사용한 것을 제외하고는 상기 실시예 1과 동일한 방법에 따라 분리막을 제조하였다.In Example 2, using the polymer solution prepared by adding 10% by weight of ethylene vinyl acetate (Hanhwa Chemical Co., Ltd.) to water and stirring at a temperature condition of 40 ℃ for 2 hours in a stirrer A separator was prepared in the same manner as in Example 1, except that the mixture was mixed at a weight ratio of polymer solution: acetone = 7: 3 and stirred at 25 ° C. for 2 hours with a power mixer.

실시예 4Example 4

상기 실시예 1에 있어서, 상기 제2 코팅층 제조시, 상기 고분자 용액과 별도로, Al2O3를 (LS235, 일본 경금속 사) 아세톤에 25 중량%로 첨가하고 비즈밀을 이용하여 25 ℃에서 2 시간 동안 밀링하여 분산시켜 무기 분산액을 제조한 후, 상기 제2 고분자 용액, 무기 분산액 및 아세톤 (대정화금 사)을 고분자 용액:무기 분산액:아세톤 = 1:1:3의 중량비로 혼합하고 파워 믹서로 25 ℃에서 2 시간 동안 교반하여 제2 코팅제를 제조한 것을 제외하고는 상기 실시예 1과 동일한 방법으로 분리막을 제조하였다. In Example 1, when preparing the second coating layer, separately from the polymer solution, Al 2 O 3 (LS235, Nippon Light Metal Co., Ltd.) was added to the acetone at 25% by weight and using a bead mill for 2 hours at 25 ℃ After milling and dispersing to prepare an inorganic dispersion, the second polymer solution, the inorganic dispersion, and acetone (a gold refiner) were mixed in a weight ratio of polymer solution: inorganic dispersion: acetone = 1: 1: 1: 3 with a power mixer. A separator was prepared in the same manner as in Example 1, except that the second coating agent was prepared by stirring at 25 ° C. for 2 hours.

비교예 1Comparative Example 1

상기 실시예 1에 있어서, 상기 제2 코팅제로 상기 제1 코팅제와 동일한 코팅제를 사용하는 것을 제외하고는 상기 실시예 1과 동일한 방법에 따라 분리막을 제조하였다.In Example 1, a separation membrane was prepared in the same manner as in Example 1 except for using the same coating agent as the first coating agent as the second coating agent.

비교예 2Comparative Example 2

상기 실시예 2에 있어서, 상기 제2 코팅제로 상기 제1 코팅제와 동일한 코팅제를 사용하는 것을 제외하고는 상기 실시예 3과 동일한 방법에 따라 분리막을 제조하였다.In Example 2, a separator was manufactured in the same manner as in Example 3, except that the same coating agent as the first coating agent was used as the second coating agent.

비교예 3Comparative Example 3

상기 실시예 1에 있어서, 제 2 코팅제로 폴리비닐리덴 플루오라이드-헥사플루오로프로필렌 코폴리머(21216, 솔베이 사)를 아세톤 (대정화금 사)에 10 중량%로 첨가하고 교반기에서 4시간 동안 25 ℃의 온도 조건에서 교반하여 고분자 용액을 제조하고, 상기 고분자 용액 및 아세톤 (대정화금 사)을 고분자 용액:아세톤 = 2:3의 중량비로 혼합하고 파워 믹서로 25 ℃에서 2 시간 동안 교반하여 사용한 것을 제외하고는 실시예 1과 동일한 방법으로 분리막을 제조하였다.In Example 1, polyvinylidene fluoride-hexafluoropropylene copolymer (21216, Solvay Co., Ltd.) was added to the acetone (coarse gold company) at 10 wt% as a second coating agent and stirred for 25 hours in a stirrer. A polymer solution was prepared by stirring at a temperature condition of ℃, and the polymer solution and acetone (a large crystal gold company) were mixed in a weight ratio of polymer solution: acetone = 2: 3 and stirred at a power mixer for 2 hours at 25 ℃. Except for the separation membrane was prepared in the same manner as in Example 1.

상기 실시예 1 내지 4 및 비교예 1 내지 3에 따른 분리막의 코팅층 조성을 하기 표 1에 정리하였다.The coating layer composition of the separator according to Examples 1 to 4 and Comparative Examples 1 to 3 are summarized in Table 1 below.

표 1 조성 PVdF-HFP PVdF SBR CMC PBMA EVA Al2O3 실시예 1 제1 코팅층 ○ - - - - - ○ 제2 코팅층 - - ○ ○ - - - 실시예 2 제1 코팅층 ○ ○ - - - - ○ 제2 코팅층 - - - - ○ - - 실시예 3 제1 코팅층 ○ ○ - - - - ○ 제2 코팅층 - - - - - ○ - 실시예 4 제1 코팅층 ○ - - - - - ○ 제2 코팅층 - - ○ ○ - - ○ 비교예 1 제1 코팅층 ○ - - - - - ○ 제2 코팅층 ○ - - - - - ○ 비교예 2 제1 코팅층 ○ ○ - - - - ○ 제2 코팅층 ○ ○ - - - - ○ 비교예 3 제1 코팅층 ○ - - - - - ○ 제2 코팅층 ○ - - - - - - Table 1 Furtherance PVdF-HFP PVdF SBR CMC PBMA EVA Al 2 O 3 Example 1 First coating layer ○ - - - - - ○ Second coating layer - - ○ ○ - - - Example 2 First coating layer ○ ○ - - - - ○ Second coating layer - - - - ○ - - Example 3 First coating layer ○ ○ - - - - ○ Second coating layer - - - - - ○ - Example 4 First coating layer ○ - - - - - ○ Second coating layer - - ○ ○ - - ○ Comparative Example 1 First coating layer ○ - - - - - ○ Second coating layer ○ - - - - - ○ Comparative Example 2 First coating layer ○ ○ - - - - ○ Second coating layer ○ ○ - - - - ○ Comparative Example 3 First coating layer ○ - - - - - ○ Second coating layer ○ - - - - - -

실험예 1 - 전극과의 접착력 측정Experimental Example 1 Measurement of Adhesion with Electrode

상기 실시예 1 내지 4 및 비교예 1 내지 3에서 제조된 각각의 분리막과 전지의 전극과의 접착력을 측정하기 위하여 하기와 같은 실험을 수행하였다. 본 실험에서 사용한 전지는 리튬 이차 전지이며, 전지의 양극 및 음극의 제조예는 다음과 같다 In order to measure the adhesive force of each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 and the electrode of the battery, the following experiment was performed. The battery used in this experiment is a lithium secondary battery, and the production examples of the positive electrode and the negative electrode of the battery are as follows.

양극의 제조Manufacture of anode

상기 실시예 1 내지 4 및 비교예 1 내지 3에서 제조된 분리막 각각을, 가로(MD) 2.5 cm × 세로(TD) 7 cm로 재단하여 각각 10개씩의 시료를 제작하였다. 양극 또한 가로(MD) 2.5 cm × 세로(TD) 10 cm 로 재단하여 각각 10개씩의 시료를 제작하였다. 상기 양극은 양극 활물질로서 LiCoO2, 결합제로서 폴리비닐리덴 플루오라이드(PVdF) 및 도전제로서 카본 블랙을 94:3:3의 중량비로 N-메틸-2-피롤리돈 용매 중에서 분산시켜 양극 활물질 슬러리를 제조하였다. 상기 양극 활물질 슬러리를 두께 20 ㎛의 알루미늄 호일에 코팅하고 건조, 압연하여 양극을 제조하였다. Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was cut to a width of 2.5 cm x 7 cm of TD to prepare 10 samples each. Anodes were also cut into 2.5 cm wide by 10 cm wide by TD to prepare 10 samples each. The positive electrode was prepared by dispersing LiCoO 2 as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, and carbon black as a conductive agent in an N-methyl-2-pyrrolidone solvent at a weight ratio of 94: 3: 3. Was prepared. The positive electrode active material slurry was coated on an aluminum foil having a thickness of 20 μm, dried, and rolled to prepare a positive electrode.

상기 코팅 분리막 시료를 유리판에 양면 테이프를 사용하여 결착시킨 후 분리막 위에 전해질(EC/EMC/DEC=3:5:2 중 1.15M LiPF6)을 약 0.2 ml 떨어뜨려 적셨다. 젖은 코팅 분리막 표면에 양극 시료를 올려 놓고 100? Hot Press를 사용하여 0.1kgf/cm2의 압력으로 3초간 눌러 준다.After the coated separator sample was bound to the glass plate using double-sided tape, about 0.2 ml of electrolyte (1.15M LiPF 6 in EC / EMC / DEC = 3: 5: 2) was dropped onto the separator. Place the anode sample on the surface of the wet coated separator and place the 100? Use Hot Press for 3 seconds at a pressure of 0.1kgf / cm 2 .

준비된 시료를 인장 강도 측정기 (UTM; Universal Test Machine)를 이용하여 상기 양극 활물질이 박리되는 데에 필요한 힘을 측정하고 그 평균값을 계산하였다.The prepared sample was measured by using a tensile strength meter (UTM; Universal Test Machine) to measure the force required to peel the positive electrode active material and to calculate the average value.

음극의 제조Preparation of Cathode

상기 실시예 1 내지 4 및 비교예 1 내지 3에서 제조된 분리막 각각을, 가로(MD) 2.5 cm × 세로(TD) 7 cm로 재단하여 각각 10개씩의 시료를 제작하였다. 음극 또한 가로(MD) 2.5 cm × 세로(TD) 10 cm 로 재단하여 각각 10개씩의 시료를 제작하였다. 여기서 사용된 음극은 음극 활물질로 구형화된 천연 흑연, 결합제로서 스티렌-부타디엔 고무 및 증점제로서 카르복시메틸 셀룰로오스를 97:1.5:1.5의 중량비로 혼합한 다음 물에 분산시켜 음극 활물질 슬러리를 제조하였다. 이 슬러리를 두께 10 ㎛의 구리 호일에 코팅하고 건조, 압연하여 음극을 제조하였다. Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was cut into a horizontal (MD) 2.5 cm × a vertical (TD) 7 cm to prepare 10 samples each. The negative electrode was also cut to 2.5 cm in width x 10 cm in length (TD) to prepare 10 samples each. The negative electrode used herein was prepared by mixing a natural graphite spherical with a negative electrode active material, styrene-butadiene rubber as a binder and carboxymethyl cellulose as a thickener in a weight ratio of 97: 1.5: 1.5, and then dispersed in water to prepare a negative electrode active material slurry. The slurry was coated on a copper foil having a thickness of 10 μm, dried, and rolled to prepare a negative electrode.

상기 코팅 분리막 시료를 유리판에 양면 테이프를 사용하여 결착 시킨 후 분리막 위에 전해질(EC/EMC/DEC=3:5:2 중 1.15M LiPF6)을 약 0.2 ml 떨어트려 적신다. 젖은 코팅 분리막 표면에 음극 시료를 올려 놓고 100 ℃ Hot Press를 사용하여 0.1kgf/cm2의 압력으로 3초간 눌러 준다.The coated separator sample was bound to the glass plate using double-sided tape, and then wetted with about 0.2 ml of electrolyte (1.15M LiPF 6 in EC / EMC / DEC = 3: 5: 2) on the separator. Place the negative electrode sample on the surface of the wet coated separator and press it for 3 seconds using a pressure of 0.1kgf / cm 2 using a 100 ℃ hot press.

준비된 시료를 인장 강도 측정기 (UTM; Universal Test Machine)를 이용하여 상기 음극 활물질이 박리되는 데에 필요한 힘을 측정하고 그 평균값을 계산하였다The prepared sample was measured by using a tensile tester (UTM; Universal Test Machine) to measure the force required to peel the negative active material and calculate the average value thereof.

실험예 2 - 분리막의 박리력 측정Experimental Example 2-Measurement of Peel Force of Separator

상기 실시예 1 내지 4 및 비교예 1 내지 3에서 제조된 분리막 각각을, 가로(MD) 2.5 cm 세로(TD) 7 cm로 재단하여 각각 10개씩의 시료를 제작하였다. 상기 각 시료를 유리판 위에 투명 양면 테이프(3M)를 이용하여 단단히 부착시킨 다음, 인장 강도 측정기 (UTM; Universal Test Machine)를 이용하여 상기 각 분리막이 박리되는 데에 필요한 힘을 측정하고 그 평균값을 계산하였다.Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was cut to a width of 2.5 cm and a length of 7 cm to prepare a sample of 10 samples. Each sample was firmly attached to the glass plate using a transparent double-sided tape (3M), and then the force required to peel each separator was calculated using a universal test machine (UTM) and the average value thereof was calculated. It was.

실험예 3 - 분리막의 열수축률 측정Experimental Example 3-Measurement of heat shrinkage rate of separator

상기 실시예 1 내지 4 및 비교예 1 내지 3에서 제조된 분리막 각각을 가로 (MD) 5 cm 세로 (TD) 5 cm로 서로 다른 10 개의 지점에서 재단한 10 개의 시편을 제작하였다. 상기 각 시편을 120 ℃의 오븐에서 1 시간 동안 방치한 다음, 각 시편의 MD 방향 및 TD 방향의 수축 정도를 측정하여 평균 열수축률을 계산하였다.Each of the separators prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was prepared with 10 specimens cut at 10 different points with 5 cm width (MD) and 5 cm length (TD). After the specimens were left in an oven at 120 ° C. for 1 hour, the average thermal shrinkage was calculated by measuring the shrinkage in the MD and TD directions of the specimens.

상기 실험예 1 내지 3에 따라 측정된 결과를 하기 표 2에 나타낸다.The results measured according to Experimental Examples 1 to 3 are shown in Table 2 below.

표 2 전극과의 접착력 (gf/cm) 박리력 (gf/cm) 열수축률 (%) 양극 음극 양극 음극 MD TD 실시예 1 40 45 400 720 4 3 실시예 2 40 25 400 350 6 5 실시예 3 40 30 400 380 6 6 실시예 4 40 40 400 700 3 3 비교예 1 12 9 12 80 7 6 비교예 2 40 8 12 50 8 6 비교예 3 12 9 120 200 7 6 TABLE 2 Adhesion with Electrode (gf / cm) Peel force (gf / cm) Heat Shrinkage (%) anode cathode anode cathode MD TD Example 1 40 45 400 720 4 3 Example 2 40 25 400 350 6 5 Example 3 40 30 400 380 6 6 Example 4 40 40 400 700 3 3 Comparative Example 1 12 9 12 80 7 6 Comparative Example 2 40 8 12 50 8 6 Comparative Example 3 12 9 120 200 7 6

상기 표 2를 참조하면, 실시예 1 내지 4는 다공성 기재 필름의 일면의 코팅층에 함유된 유기 바인더와 타면의 코팅층에 함유된 유기 바인더가 상이한 비대칭성 코팅층이 형성된 다공성 분리막으로서, 양면에 포함된 유기 바인더가 동일한 분리막(비교예 1 내지 3)에 비해, 박리력이 300 gf/cm 이상 및 음극의 접착력이 20 gf/cm 이상으로 우수함을 확인하였다.Referring to Table 2, Examples 1 to 4 are porous separators in which an asymmetric coating layer is formed in which an organic binder contained in a coating layer on one side of a porous base film and an organic binder contained in a coating layer on the other side are formed. Compared to the same separation membrane (Comparative Examples 1 to 3), the binder was found to have an excellent peeling force of 300 gf / cm or more and an adhesive strength of the negative electrode of 20 gf / cm or more.

또한, 실시예의 열수축률은 종 방향(MD, Machine Direction) 및 횡 방향(TD, Transverse Direction)으로 각각 7 % 이하이고, 적어도 어느 한 방향의 열수축률이 5 % 이하로 나타나, 열에 의한 분리막의 안정성이 우수함을 확인하였다.In addition, the thermal contraction rate of the embodiment is 7% or less in the longitudinal direction (MD, Machine Direction) and the transverse direction (TD, Transverse Direction), respectively, the thermal contraction rate of at least one direction is 5% or less, so that the stability of the separator by heat This excellence was confirmed.

상기의 결과를 종합하여 볼 때, 코팅층과 기재 필름 사이 접착력이 충분히 강하여 열에 의한 기재 필름의 수축을 감소시킬 수 있고, 코팅층과 전극 사이의 접착력 또한 우수하여 양극과 음극의 단락을 감소시킬 수 있으므로, 전극의 단락을 방지하고 열적 안정성을 향상시킨 전지에 유용하게 사용될 수 있을 것을 확인하였다. In view of the above results, since the adhesion between the coating layer and the base film is sufficiently strong to reduce the shrinkage of the base film due to heat, and the adhesion between the coating layer and the electrode is also excellent, which can reduce the short circuit of the positive electrode and the negative electrode, It was confirmed that it can be usefully used in a battery that prevents short circuit of the electrode and improves thermal stability.

이상으로 본 발명의 특정한 부분을 상세히 기술하였는 바, 당업계의 통상의 지식을 가진 자에게 있어서, 이러한 구체적 기술은 단지 바람직한 실시예일 뿐이며, 이에 의해 본 발명의 범위가 제한되는 것이 아닌 점은 명백할 것이다. 따라서, 본 발명의 실질적인 범위는 첨부된 청구항들과 그것들의 등가물에 의하여 정의된다고 할 것이다.Having described the specific part of the present invention in detail, it will be apparent to those skilled in the art that such a specific description is only a preferred embodiment, thereby not limiting the scope of the present invention. will be. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (15)

다공성 기재 필름;Porous base film; 상기 다공성 기재 필름의 일면에 형성되고 무기 입자를 함유하는 제1 코팅층; 및A first coating layer formed on one surface of the porous base film and containing inorganic particles; And 상기 다공성 기재 필름의 타면에 형성되고 스타이렌-부타디엔 고무, 카르복시 메틸 셀룰로오스, 폴리 부틸 아크릴레이트 및 에틸렌 바이닐 아세테이트로 이루어진 군으로부터 선택된 단독 또는 이들의 혼합물을 함유하는 제2 코팅층을 포함하며, A second coating layer formed on the other side of the porous base film and containing a single or a mixture thereof selected from the group consisting of styrene-butadiene rubber, carboxy methyl cellulose, poly butyl acrylate and ethylene vinyl acetate, 상기 제2 코팅층과 전지의 음극과의 접착력이 20 gf/cm 이상인, 다공성 분리막.Adhesiveness between the second coating layer and the negative electrode of the battery is 20 gf / cm or more, porous separator. 제1항에 있어서, 상기 제1 코팅층은 상기 제2 코팅층의 스타이렌-부타디엔 고무, 카르복시 메틸 셀룰로오스, 폴리 부틸 아크릴레이트 및 에틸렌 바이닐 아세테이트로 이루어진 군으로부터 선택된 단독 또는 이들의 혼합물과 상이한 유기 바인더를 추가로 포함하는, 다공성 분리막.The organic coating of claim 1, wherein the first coating layer adds an organic binder different from a singly or a mixture thereof selected from the group consisting of styrene-butadiene rubber, carboxy methyl cellulose, poly butyl acrylate, and ethylene vinyl acetate of the second coating layer. Containing, porous separator. 제1항에 있어서, 상기 제1 코팅층은 폴리비닐리덴 플루오라이드-헥사플루오로프로필렌 코폴리머를 포함하는, 다공성 분리막.The porous membrane of claim 1, wherein the first coating layer comprises polyvinylidene fluoride-hexafluoropropylene copolymer. 제3항에 있어서, 상기 제1 코팅층은 폴리비닐리덴 플루오라이드 호모 폴리머를 추가로 포함하는, 다공성 분리막.The porous separator of claim 3, wherein the first coating layer further comprises a polyvinylidene fluoride homopolymer. 제1항에 있어서, 상기 무기 입자는 Al2O3, SiO2, B2O3, Ga2O3, TiO2 및 SnO2로 이루어진 군에서 선택되는 1 종 이상을 포함하는, 다공성 분리막.The porous separator of claim 1, wherein the inorganic particles include one or more selected from the group consisting of Al 2 O 3 , SiO 2 , B 2 O 3 , Ga 2 O 3 , TiO 2, and SnO 2 . 제1항에 있어서, 상기 제2 코팅층은 스타이렌-부타디엔 고무 및 카르복시 메틸 셀룰로오스를 포함하는, 다공성 분리막.The porous separator of claim 1, wherein the second coating layer comprises styrene-butadiene rubber and carboxy methyl cellulose. 제1항에 있어서, 상기 분리막의 박리력은 300 gf/cm 이상인, 다공성 분리막.The porous membrane of claim 1, wherein the separation force of the separator is 300 gf / cm or more. 제1항에 있어서, 상기 분리막을 120 ℃에서 1시간 동안 방치한 후의 열수축율이 종 방향(MD, Machine Direction) 및 횡 방향(TD, Transverse Direction)으로 각각 7 % 이하인, 다공성 분리막.The porous membrane of claim 1, wherein the heat shrinkage rate of the separator after being left at 120 ° C. for 1 hour is 7% or less in the machine direction (MD) and the transverse direction (TD), respectively. 제1항에 있어서, 상기 분리막을 120 ℃에서 1시간 동안 방치한 후의 열수축율이 종 방향(MD, Machine Direction) 및 횡 방향(TD, Transverse Direction)으로 각각 5 % 이하인, 다공성 분리막. The porous membrane of claim 1, wherein the thermal contraction rate after leaving the separator at 120 ° C. for 1 hour is 5% or less in the machine direction (MD) and the transverse direction (TD), respectively. 제1항에 있어서, 상기 전지는 리튬 이차 전지인, 다공성 분리막.The porous separator of claim 1, wherein the battery is a lithium secondary battery. 제10항에 있어서, 상기 전지의 음극은 결정질 또는 비정질 탄소를 포함하는, 다공성 분리막.The porous separator of claim 10, wherein the negative electrode of the cell comprises crystalline or amorphous carbon. 양극, 음극, 분리막 및 전해질을 포함하며,A positive electrode, a negative electrode, a separator and an electrolyte, 상기 분리막은 상기 음극 상에 형성된 코팅층을 포함하고, 상기 코팅층은 스타이렌-부타디엔 고무, 카르복시 메틸 셀룰로오스, 폴리 부틸 아크릴레이트 및 에틸렌 바이닐 아세테이트로 이루어진 군으로부터 선택된 단독 또는 이들의 혼합물을 함유하며. The separator comprises a coating layer formed on the anode, the coating layer contains a single or a mixture thereof selected from the group consisting of styrene-butadiene rubber, carboxy methyl cellulose, poly butyl acrylate and ethylene vinyl acetate. 상기 코팅층과 상기 음극과의 접착력이 20 gf/cm 이상인, 전기 화학 전지.The adhesion between the coating layer and the negative electrode is 20 gf / cm or more, electrochemical cell. 제12항에 있어서, 상기 코팅층은 상기 음극과 직접 접하여 형성되는, 전기 화학 전지.The electrochemical cell of claim 12, wherein the coating layer is formed in direct contact with the cathode. 제12항에 있어서, 상기 전기 화학 전지는 리튬 이차 전지인, 전기 화학 전지.The electrochemical cell of claim 12, wherein the electrochemical cell is a lithium secondary battery. 제12항에 있어서, 상기 음극은 결정질 또는 비정질 탄소를 포함하는, 전기 화학 전지.The electrochemical cell of claim 12, wherein the negative electrode comprises crystalline or amorphous carbon.
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