WO2024205129A1 - Séparateur pour batterie secondaire et batterie secondaire le comprenant - Google Patents

Séparateur pour batterie secondaire et batterie secondaire le comprenant Download PDF

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Publication number
WO2024205129A1
WO2024205129A1 PCT/KR2024/003562 KR2024003562W WO2024205129A1 WO 2024205129 A1 WO2024205129 A1 WO 2024205129A1 KR 2024003562 W KR2024003562 W KR 2024003562W WO 2024205129 A1 WO2024205129 A1 WO 2024205129A1
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Prior art keywords
meth
separator
secondary battery
particle
group
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Ceased
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PCT/KR2024/003562
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English (en)
Korean (ko)
Inventor
김병수
김수희
김하나
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Samsung SDI Co Ltd
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Samsung SDI Co Ltd
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Priority claimed from KR1020230056577A external-priority patent/KR20240144806A/ko
Application filed by Samsung SDI Co Ltd filed Critical Samsung SDI Co Ltd
Publication of WO2024205129A1 publication Critical patent/WO2024205129A1/fr
Anticipated expiration legal-status Critical
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding 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
    • 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
    • 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
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—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
    • 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 for a secondary battery and a secondary battery including the same.
  • lithium batteries In order to meet the miniaturization and high performance of various devices, miniaturization and weight reduction of lithium batteries are becoming important. In addition, in order to be applied to fields such as electric vehicles, the discharge capacity, energy density, and cycle characteristics of lithium batteries are becoming important. In order to meet the above-mentioned purposes, lithium batteries with high discharge capacity per unit volume, high energy density, high capacity, and excellent life characteristics and safety are required.
  • a separator is arranged.
  • An electrode assembly including a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode is rolled into a jellyroll shape, and the jellyroll is rolled to improve the adhesion between the positive electrode/negative electrode and the separator in the electrode assembly.
  • the interfacial resistance between the positive electrode and the separator, and the negative electrode and the separator increases, and as the charge and discharge cycle of the lithium battery is repeated, the capacity and high-rate charge and discharge characteristics may deteriorate.
  • One aspect is to provide a separator for secondary batteries with improved adhesion and safety.
  • Another aspect is to provide a secondary battery having excellent capacity and life characteristics and improved safety, including the above-described separator.
  • a porous substrate comprising an inorganic layer positioned on at least one surface of the porous substrate, and an adhesive layer positioned on the inorganic layer,
  • the above adhesive layer contains first and second particles which are organic binders having different particle sizes
  • a secondary battery separator is provided in which the mixing volume ratio of the first and second particles is 1:5 to 1:35.
  • a secondary battery which includes a positive electrode, a negative electrode, and a separator interposed therebetween and described above.
  • a secondary battery separator contains an adhesive layer with improved adhesive strength, so that air permeability is good, and the adhesive strength between the separator and the electrode after charge and discharge is excellent, so that deformation of the battery does not occur. Therefore, by using this, a secondary battery with improved capacity, lifespan, and safety can be provided.
  • Figure 1 is a schematic diagram showing a cross-section of a separator of a lithium battery according to an embodiment.
  • Figure 2 is a schematic diagram showing a cross-section of a separator of a lithium battery according to another embodiment.
  • Figure 3 is a schematic diagram showing a cross-section of a separator of a lithium battery according to another embodiment.
  • Figure 4 is a schematic diagram of a lithium battery according to an embodiment.
  • Electrode assembly 170 Case
  • Lithium secondary batteries generally place a separator between the positive and negative electrodes and go through a hot press process at a certain temperature and pressure. Through this hot press process, the adhesive strength between the positive and negative electrode and the separator interface increases, thereby holding the shape of the battery. However, if the adhesive strength is insufficient, the interface with the electrodes becomes lifted, which is the fundamental cause of the continuous decrease in capacity according to the cycle of the lithium polymer battery and the deterioration of the high-rate charge and discharge characteristics. In addition, the safety of the battery is reduced, so improvement of this is required.
  • a porous substrate comprising an inorganic layer positioned on at least one surface of the porous substrate, and an adhesive layer positioned on the inorganic layer, in order to solve the above-described problem.
  • the invention has been completed for a secondary battery separator, wherein the adhesive layer contains first and second particles, which are organic binders with different particle sizes, and the volume ratio of the first and second particles is 1:5 to 1:35.
  • an adhesive layer uses two types of organic binders with different particle sizes to provide a separator with improved adhesion to an inorganic layer, thereby more strongly controlling the bonding force between an electrode and a separator, thereby enabling the manufacture of a lithium secondary battery having stable cell performance without abnormal behavior such as cell swelling during charge and discharge.
  • the volume ratio of the first particle to the second particle is 1:5 to 1:35, 1:8 to 1:30, for example, 1:20.
  • the volume ratio of the second particle is larger than the above-described range of the volume ratio of the first particle to the second particle, the resistance increases, and when the volume ratio of the second particle is smaller than the above-described range, the cell life is reduced due to a decrease in the bending strength.
  • the volume ratio of the first particle to the second particle is related to the diameter ratio of the first particle to the second particle, and the diameter ratio of the first particle to the second particle is, for example, 1:1.25 to 1:3.5, 1:2 to 1:3.5, 1:2.5 to 1:3.5, or 1:2.5 to 1:3.0.
  • the mixing weight ratio of the first particles and the second particles contained in the adhesive layer is 1:99 to 99:1, 1:90 to 90:1, 1:80 to 80:1, 70:1 to 1:70, 50:1 to 1:50, 30:1 to 1:30, 20:1 to 1:1, 10:1 to 1:1, or 5:1 to 1:1.
  • the mixing weight ratio of the first particle to the second particle is 20:1 to 1:1, 10:1 to 1:1, 10:1 to 1.5:1, 8:1 to 1.5:1, 7:1 to 1.5:1, 6:1 to 1.5:1, 6:1 to 1.5:1, 5.5:1 to 1.5:1, 5.5:1 to 1.7:1, 5.3:1 to 1.9:1, 5.13:1 to 1.97:1, or 5:1 to 2;1.
  • the weight ratio of the first particle to the second particle contained in the adhesive layer is 5:1 to 1:1, 4:1 to 1:1, or 3:1 to 1:1.
  • the first particle has a smaller size than the second particle.
  • the size of the first particle is 100 to 300 nm, or 150 to 250 nm, and the size of the second particle is 500 to 900 nm, or 500 to 870 nm.
  • size refers to the particle diameter when the particle to be measured is spherical, and refers to the major axis length when the particle is non-spherical.
  • the particle diameter is, for example, an average particle diameter
  • the major axis length is, for example, an average major axis length.
  • the average particle diameter and the average major axis length represent the average values of the measured particle diameters and the measured major axis lengths, respectively.
  • the size of the particle in this disclosure refers to the average size of the particle.
  • the size of the particles can be evaluated using a particle size analyzer, a scanning electron microscope, or a transmission electron microscope.
  • a particle size analyzer for example, a HORIBA, LA-950 laser particle size analyzer can be used as a particle size analyzer.
  • the average particle diameter is, for example, an average particle diameter observed using a scanning electron microscope (SEM), and can be calculated as an average value of the particle diameters of about 10 to 30 particles using an SEM image.
  • SEM scanning electron microscope
  • the average particle diameter is represented by D50.
  • D50 means the average diameter of particles corresponding to 50% of the cumulative volume in the particle size distribution, and means the value of the particle diameter corresponding to 50% of the smallest particle in the cumulative distribution curve from the smallest particle to the largest particle when the total number of particles is 100%.
  • D50 can be measured using a particle size analyzer.
  • D50 can be measured using a measuring device that uses dynamic light-scattering, and data analysis is performed to count the number of particles for each particle size range, and then easily obtained through calculation.
  • the glass transition temperature of the first particle is not indicated.
  • the thermal decomposition temperature of the first particle is 200°C or higher, 220°C or higher, 250°C or higher, for example, 250 to 300°C.
  • the first particle can act as a filler and exhibit high heat-resistant particle characteristics.
  • the glass transition temperature of the second particle is 40°C to 80°C, 42°C to 78°C, 45°C to 75°C, 48°C to 73°C, or 50°C to 70°C.
  • the bonding force between the electrode and the adhesive layer becomes stronger.
  • the total content of the first and second particles is 60 to 98 parts by weight, 62 to 98 parts by weight, 63 to 98 parts by weight, 64 to 98 parts by weight, for example, 65 to 98 parts by weight, based on 100 parts by weight of the total weight of the adhesive layer.
  • the adhesive strength between the electrode and the separator is excellent.
  • the above first and second particles are organic polymers.
  • the weight average molecular weight of the organic polymer is 50,000 to 500,000, 100,000 to 480,000, 120,000 to 470,000, 150,000 to 450,000, 200,000 to 450,000, for example, 300,000 to 450,000.
  • the adhesive strength of the membrane is improved.
  • the first particle and the second particle are, for example, a butyl methacrylate-ethylene glycol dimethacrylate copolymer, a butyl methacrylate-ethylene glycol dimethacrylate-acrylonitrile copolymer, a styrene-ethylhexylacrylate copolymer, a styrene-ethylhexylacrylate-acrylonitrile copolymer, a styrene-butadiene rubber, an acrylated styrene-butadiene rubber, an acrylonitrile-butadiene rubber, an acrylonitrile-butadiene-styrene rubber, an acrylic rubber, a butyl rubber, a fluoroelastomer, a polytetrafluoroethylene, a polyethylene, a polypropylene, an ethylene propylene copolymer, a polyethylene oxide, a polyvinyl pyrrolidone,
  • the first particle is, for example, a polymer obtained by a polymerization reaction of a polymerizable monomer having a crosslinking functional group, wherein the crosslinking functional group is, for example, a glycidyl group, an amino group, an N-methylol group, or a vinyl group.
  • the polymerizable monomer having the above crosslinking functional group is, for example, a hydroxy ester of an ethylenically unsaturated carboxylic acid, a glycidyl ester of an ethylenically unsaturated carboxylic acid, an amino ester of an ethylenically unsaturated carboxylic acid, an ethylenically unsaturated amide containing a methylol group, a monomer having two or more vinyl groups, or a combination thereof.
  • the hydroxy ester of the ethylenically unsaturated carboxylic acid includes (meth)acrylic acid hydroxypropyl, (meth)acrylic acid hydroxyethyl or a combination thereof, the glycidyl ester of the ethylenically unsaturated carboxylic acid includes glycidyl (meth)acrylate.
  • the amino ester of the ethylenically unsaturated carboxylic acid includes dimethyl amino ethyl (meth)acrylate
  • the methylol group-containing ethylenically unsaturated amide includes N-methylol (meth)acryl amide, N,N-dimethylol (meth)acryl amide or a combination thereof
  • the monomer having two or more vinyl groups may include ethylene di (meth)acrylate, divinyl benzene or a combination thereof.
  • the first particle is, for example, a butyl methacrylate-ethylene glycol dimethacrylate copolymer, a butyl methacrylate-ethylene glycol dimethacrylate-acrylonitrile copolymer or a combination thereof.
  • the second particle is, for example, a styrene-ethylhexylacrylate copolymer, a styrene-ethylhexylacrylate-acrylonitrile copolymer, or a combination thereof.
  • the adhesive layer may further contain an additional binder such as a fluorine-based resin, a polyacrylic acid-based compound, or a combination thereof.
  • the content of the additional binder is 1 to 3 parts by weight based on the total weight of the adhesive layer.
  • the bonding force between the electrode and the separator can be more effectively controlled.
  • the weight average molecular weight of the polyacrylic acid compound is 50,000 to 500,000, for example 150,000 to 450,000, for example 300,000 to 450,000.
  • the weight average molecular weight of the (meth)acrylic polymer is within the above range, the adhesive strength of the membrane is improved.
  • the weight average molecular weight can be evaluated by gel permeation chromatography.
  • Polyacrylic acid compounds include, for example, polyacrylic acid, polymethylacrylic acid, polyethylacrylic acid, polybutylacrylic acid, polyhexylacrylic acid, polyhydroxyethylmethacrylic acid, polyaminoacrylic acid, or combinations thereof.
  • the fluorine-based resin acts as a binder to fix inorganic particles on the porous substrate, and at the same time provides excellent adhesive strength so that one side of the adhesive layer can be well attached to the porous substrate and the other side can be well attached to the electrode.
  • the average particle size of the fluorine-based resin as the binder is 100 to 300 nm. When the fluorine-based resin has the above-described average particle size, the adhesive strength of the adhesive layer to the porous substrate is very excellent. Even when the separator is exposed to high temperatures, the binder has high heat resistance and can maintain the matrix form of the network structure.
  • the glass transition temperature (Tg) value of the fluorinated resin is 50°C or higher, and the weight average molecular weight is 200,000 to 3,000,000 g/mol, 200,000 to 2,500,000 g/mol, 200,000 to 2,000,000 g/mol, 300,000 to 1,500,000 g/mol, or 300,000 to 1,200,000 g/mol.
  • the weight average molecular weight may be a polystyrene-converted average molecular weight measured using gel permeation chromatography.
  • the membrane can have excellent adhesive strength.
  • the fluorinated resin is polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, or a combination thereof.
  • the methacrylic binder is polyacrylate, polymethacrylate, polybutylacrylate, polyacrylonitrile, or a combination thereof.
  • the vinylidene fluoride repeating unit may be included in an amount of 90 mol% to 99.5 mol%, 93 mol% to 99 mol%, or 95 mol% to 99 mol%.
  • the vinylidene fluoride repeating unit is included in the above range, the vinylidene fluoride-hexafluoropropylene copolymer can secure excellent adhesive strength and electrolyte impregnation property, etc.
  • the crystallinity of the above fluorinated resin may be 35% to 45%, for example, 38% to 45%, or 40% to 45%.
  • a separator having adhesive strength and containing a fluorinated resin having such a crystallinity exhibits excellent adhesive strength to a substrate.
  • the mixing weight ratio of the total weight of the first particle and the second particle to the (meth)acrylic binder can be controlled to a weight ratio of 0.01:1 to 1:1, a weight ratio of 0.05:1 to 1:1, a weight ratio of 0.1:1 to 1:1, a weight ratio of 0.2:1 to 1:1, or a weight ratio of 0.25:1 to 0.75:1.
  • the adhesive layer may further include at least one selected from the group consisting of, for example, polyvinylpyrrolidone, polyvinylacetate, polyethyleneoxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, and acrylonitrile-styrene-butadiene copolymer.
  • Secondary batteries include, for example, lithium secondary batteries.
  • a secondary battery separator (10) according to one embodiment comprises a porous substrate (20) and inorganic layers (30) positioned on both sides of the porous substrate (20).
  • the separator of Fig. 1 has an inorganic layer (30) positioned on both sides of a porous substrate (20), but the inorganic layer (30) may be positioned on one side of the porous substrate as shown in Fig. 3.
  • an adhesive layer (40) is positioned on top of the inorganic layer (30).
  • the above adhesive layer (40) contains first particles and second particles having different particle sizes, and the volume ratio of the first particles and the second particles is 1:8 to 1:40.
  • the separator (10) can exhibit improved heat resistance, stability, and adhesive strength.
  • the thickness of the adhesive layer (40) is 0.01 ⁇ m to 10 ⁇ m, 0.01 ⁇ m to 8 ⁇ m, 0.01 ⁇ m to 6 ⁇ m, 0.01 ⁇ m to 4 ⁇ m, or 0.04 ⁇ m to 1 ⁇ m. When the thickness of the adhesive force is within the above range, excellent adhesive force is exhibited.
  • the thickness of the adhesive layer is measured using a film thickness measuring device. In the present disclosure, the thickness represents an average thickness.
  • a separation membrane may further have an inorganic layer (30) formed on the other side of the porous substrate (20) as shown in Fig. 2.
  • the inorganic layer (30) disposed on the other side of the porous substrate (20) may have the same or different composition as the inorganic layer (40) disposed on the one side of the porous substrate (20).
  • a separator may have a laminated structure in which an adhesive layer (40) is arranged on the other side of a porous substrate (20), although this is not shown in the drawing.
  • the inorganic particles contained in the inorganic layer (40) are not particularly limited, and inorganic particles commonly used in the relevant technical field can be used.
  • Specific examples of the inorganic particles that can be used in the present invention include at least one selected from Al 2 O 3 , SiO 2 , B 2 O 3 , Ga 2 O 3 , TiO 2 , SnO 2 , boehmite, BaSO 4 , MgO, Mg(OH) 2 , clay, ZnO, CaO, CeO 2 , NiO, GaO, ZrO2, Y 2 O 3 , SrTiO 3 and BaTiO 3 .
  • the inorganic particles can be used alone or in combination of two or more of the above-described materials. More specifically, the inorganic particles can be used Al 2 O 3 (alumina).
  • the size of the inorganic particles is, for example, 1 ⁇ m to 20 ⁇ m, 2 to 15 ⁇ m, or 3 to 12 ⁇ m.
  • size means an average size, and when the particles are spherical, it means the average particle diameter, and when the particles are non-spherical, it means the average major axis length.
  • the average particle diameter means D50 on a volume basis.
  • the average particle diameter is measured using a measuring device such as a laser diffraction method or a dynamic light scattering method, for example.
  • the average particle diameter is measured using, for example, a laser scattering particle size distribution meter (e.g., Horiba LA-920), and is the value of the median particle diameter (D50) when 50% is accumulated from the small particle side in volume conversion.
  • a laser scattering particle size distribution meter e.g., Horiba LA-920
  • the dispersibility and coating processability of the inorganic particles within the inorganic layer can be prevented from deteriorating, and the thickness of the inorganic layer can be appropriately controlled to increase the mechanical properties.
  • the size of the pores created in the separator can be appropriately controlled to reduce the possibility of an internal short circuit occurring during charging and discharging of the battery.
  • the inorganic particles are present in an amount of 50 to 95 parts by weight, 55 to 95 parts by weight, 58 to 95 parts by weight, 60 to 95 parts by weight, 62 to 95 parts by weight, 65 to 95 parts by weight, 68 to 95 parts by weight, 70 to 95 parts by weight, 72 to 95 parts by weight, or 75 to 95 parts by weight, based on 100 parts by weight of the total weight of the inorganic layer.
  • the content of the inorganic particles is within the above range, the heat shrinkage of the separator can be effectively suppressed.
  • the inorganic particles are contained within the above range, the heat dissipation properties of the inorganic particles can be sufficiently exhibited, and the heat shrinkage of the separator can be effectively suppressed.
  • the inorganic layer (30) constituting the separator (10) is a heat-resistant layer, and the shrinkage and rupture characteristics are not reduced at high temperatures and the adhesion to the substrate is improved.
  • the thickness of the inorganic layer (30) is 0.01 ⁇ m to 20 ⁇ m, 0.1 ⁇ m to 20 ⁇ m, 1 ⁇ m to 20 ⁇ m, 1 ⁇ m to 15 ⁇ m, 1 ⁇ m to 13 ⁇ m, 1 ⁇ m to 10 ⁇ m, 1 ⁇ m to 8 ⁇ m, 1 ⁇ m to 6 ⁇ m, or 1 ⁇ m to 5 ⁇ m.
  • the inorganic layer (30) contains inorganic particles and a binder.
  • the binder may be a crosslinkable binder, a non-crosslinkable binder, or a combination thereof.
  • a crosslinkable binder refers to a material that can cause a crosslinking reaction to produce a crosslinked structure binder.
  • the crosslinkable binder can be selected from a monomer, an oligomer, a polymer, or a mixture thereof having one or more crosslinking functional groups.
  • the monomer, oligomer or polymer having one or more functional groups has one or more functional groups selected from the group consisting of, for example, an acrylate group, a vinyl group, a hydroxyl group, an epoxy group, an oxane group, an oxetane group, a carboxyl group, an amine group, an oxazoline group, an ester group and an isocyanate group.
  • the number of functional groups is two or more, three or more, or four or more.
  • Crosslinking binders include, for example, alkyl (meth)acrylates such as methyl methacrylate, methyl acrylate; bifunctional (meth)acrylates such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, di(meth)acrylate of polyoxyethylene/polyoxypropylene copolymer, butanediol di(meth)acrylate, hexamethylene glycol di(meth)acrylate;
  • the acrylate include at least one selected from the group consisting of trifunctional (meth)acrylates such as trimethylol propane tri(meth)acrylate, glycerin tri(meth)acrylate, tri(meth)acrylate of an ethylene oxide adduct of glycerin, tri(meth)acrylate of a propylene oxide adduct of glycerin, tri(meth
  • crosslinking binders examples include vinylpyrrolidone, vinylcaprolactam, vinylimidazole, vinylmethylacetamide, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, heptyl vinyl ether, octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, cyclohexyl vinyl ether, ethylhexyl vinyl ether, dodecyl vinyl ether, and octadecyl vinyl ether.
  • Crosslinking binders include, for example, biphenol, bisphenol A, methanediol, ethanediol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, and decanediol.
  • Examples of monomers, oligomers, or polymers having one or more epoxy groups include diepoxyalkanes such as diepoxyethane, diepoxypropane, diepoxybutane, diepoxypentane, diepoxyhexane, diepoxyheptane, diepoxyoctane, diepoxynonane, and diepoxydodecane; glycidyl ethers such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, brominated bisphenol A diglycidyl ether, phenol novolac glycidyl ether, and cresol novolac glycidyl ether; Examples thereof include glycidyl esters such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; glycidyl amines such as glycidyl isocyanurate and tetraglycidyl diamin
  • Crosslinking binders are, for example, 4,4'-diphenylenemethane diisocyanate, toluene diisocyanate, tolylene diisocyanate, naphthylene diisocyanate, 4,4'-dicyclohexylenemethane diisocyanate, cyclohexylene diisocyanate, 3,3'-dimethylphenylene diisocyanate, diphenylmethane diisocyanate, 3,3'-dimethyldiphenylenemethane diisocyanate, 4,6'-xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,5,5-trimethylcyclohexylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, m-xylene diisocyanate, trimethylxylene diisocyanate, p-phenylene diiso
  • a compound represented by the following chemical formula 1 can be used as a crosslinking binder.
  • X 1 to X 3 are each an oxyethylene group
  • X 4 is an oxyethylene group or an alkyl group having 1 to 10 carbon atoms
  • R 1 to R 4 are each independently any one selected from the group consisting of a (meth)acrylate group, a hydroxyl group, a carboxyl group, an ester group, a cyanate group, an isocyanate group, an amino group, a thiol group, an alkoxy group having 1 to 10 carbon atoms, a vinyl group, and a heterocyclic group
  • a 1 to a 4 are each an integer of 1 to 10
  • n 1 to n 3 are each an integer of 0 to 10
  • at least one of n 1 to n 4 is an integer of 1 to 10, provided that when X 4 is the oxyethylene group, n 4 is an integer of 1 to 10, m is 1, and X 4 is the oxyethylene group having 1 to 10 carbon atoms.
  • n 4 is 1 and
  • the ester group may be represented by -COOR
  • the amino group may be represented by -NR a R b
  • the R, R a and R b may each independently be any one selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkynyl group having 4 to 20 carbon atoms, and an aryl group having 6 to 30 carbon atoms.
  • the heterocyclic group may be one selected from the group consisting of a heterocycloalkyl group having 2 to 20 carbon atoms, a heterocycloalkenyl group having 3 to 20 carbon atoms, a heterocycloalkynyl group having 3 to 20 carbon atoms, and a heteroaryl group having 6 to 20 carbon atoms, and may include a hetero atom selected from N, O, and S. Examples thereof include an epoxy group or an oxetane group.
  • the compound of the above chemical formula 1 may include, for example, a compound of the following chemical formula 2 or 3.
  • R 5 can be an alkyl group having 1 to 10 carbon atoms
  • n 5 to n 7 can each be an integer of 1 to 5
  • a 5 to a 12 can each be an integer of 1 to 10.
  • Compounds of formula 1 include, for example, ethoxylated pentaerythritol tetraacrylate or ethoxylated trimethylolpropane triacrylate.
  • the crosslinking binder is 1 to 10 parts by weight, or 1 to 5 parts by weight, based on 100 parts by weight of the total weight of the inorganic layer. In the above range, the heat shrinkage resistance and fracture properties are excellent.
  • the inorganic particles contained in the inorganic layer may be surface-treated so as to be able to react with the crosslinking binder.
  • the inorganic particles may be surface-treated with, for example, a functional group capable of reacting with a functional group of the crosslinking binder.
  • a crosslinking reaction occurs due to a reaction between the functional group of the inorganic particles and the functional group of the crosslinking binder, and a crosslinking reaction of the functional groups of the inorganic particles also occurs simultaneously, thereby enhancing the bonding strength between the inorganic particles and the crosslinking binder, and improving the adhesion to the substrate or the coating density.
  • the crosslinking binder has an acrylate functional group
  • the inorganic particles may be surface-treated so as to have an acrylate group.
  • a binder including an aqueous cross-linking reactive acrylamide copolymer can be used as a cross-linking binder contained in an inorganic layer.
  • the aqueous cross-linking reactive acrylamide copolymer contains two or more cross-linkable cross-linking reactive groups. It can be used in a one-component form without a cross-linking agent, and the two or more cross-linking reactive groups can cause a cross-linking reaction with each other through a self-condensation reaction. Through this, a membrane inorganic layer can be formed, thereby providing a membrane having high heat resistance characteristics.
  • the crosslinking reactive group may include at least one first functional group selected from a carboxyl group, an amine group, and an isocyanate group; and at least one second functional group selected from a hydroxyl group, an epoxy group, and an oxazoline group; and a crosslinking reaction may occur between the first functional group and the second functional group to enable bonding.
  • the crosslinking reactive group may include a carboxyl group and a hydroxyl group.
  • the equivalent ratio of the first functional group and the second functional group may be in the range of 30:70 to 70:30.
  • the equivalent ratio of the first functional group and the second functional group may be, for example, in the range of 35:65 to 65:35, in the range of 40:60 to 60:40, or in the range of 45:55 to 55:45, for example, in the range of about 50:50.
  • a crosslinking reaction may smoothly occur between the first functional group and the second functional group.
  • the acrylamide copolymer includes an (N-substituted) amide monomer
  • the (N-substituted) amide monomer is an N,N-dialkyl (meth)acrylamide such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N-diisopropyl (meth)acrylamide, N,N-di (n-butyl) (meth)acrylamide, N,N-di (t-butyl) (meth)acrylamide, N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-n-butyl (meth)acrylamide, N-methylol (meth)acrylamide, It may include at least one selected from the group consisting of N-ethyl
  • the content of the (N-substituted) amide monomer is 30 to 90 mol%, 40 to 80 mol%, or 50 to 70 mol%, based on the total mol of monomer components constituting the acrylamide copolymer.
  • the acrylamide-based copolymer comprises: an (N-substituted) amide-based monomer; And a carboxyl group-containing monomer, a (meth)acrylic acid alkyl monomer, a hydroxyl group-containing monomer, an isocyanate group-containing monomer, an oxazoline group-containing monomer, a hydroxyl group-containing monomer, a polyfunctional (meth)acrylate monomer, an acid anhydride group-containing monomer, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a succinimide monomer, a maleimide monomer, an itaconimide monomer, a cyano-containing monomer, a (meth)acrylic acid aminoalkyl monomer, a (meth)acrylic acid alkoxyalkyl monomer, an epoxy group-containing acrylic monomer, an acrylic acid ester monomer having a heterocycle, a halogen atom
  • two or more types of cross-linkable functional groups may be present in the (N-substituted) amide monomer and the acrylic monomer, or may be present only in the acrylic monomer.
  • acrylic monomers include carboxyl group-containing monomers such as acrylic acid, (meth)acrylic acid, carboxyethyl acrylate, carboxypentylacrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid;
  • a (meth)acrylic acid alkyl monomer having a straight or branched alkyl group having 1 to 20 carbon atoms in the ester moiety specifically, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-
  • examples thereof include: (meth)acrylic acid esters having an alicyclic hydrocarbon group, such as acryloylmorpholine; cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; (meth)acrylic acid esters having an aromatic hydrocarbon group, such as phenyl (meth)acrylate and phenoxyethyl (meth)acrylate; (meth)acrylic acid esters obtained from terpene compound derivative alcohols; and the like.
  • the acrylamide copolymer can be used alone or in combination of two or more of the above-described acrylic monomers.
  • the molar ratio of the (N-substituted) amide monomer and the acrylic monomer may be in the range of 1:99 to 99:1, 20:80 to 80:20, 30:70 to 70:30, 40:60 to 60:40, or 50:50. In the above range, a separation membrane coating layer with improved heat resistance can be formed.
  • the weight average molecular weight of the acrylamide copolymer is 100,000 to 1,000,000 g/mol, 150,000 to 800,000 g/mol, 180,000 to 750,000 g/mol, 200,000 to 700,000 g/mol, 250,000 to 650,000 g/mol, or 300,000 to 600,000 g/mol.
  • the acrylamide-based copolymer may have a glass transition temperature of 150° C. or higher, 150° C. to 300° C., 170° C. to 280° C., or 190° C. to 250° C.
  • a highly heat-resistant inorganic membrane layer can be formed.
  • the acrylamide-based copolymer may be, for example, an acrylic acid-acrylamide-(2-acrylamido)-(2-methylpropanesulfonic acid) copolymer, an aqueous cross-linking reactive polyacrylamide-acrylic acid-hydroxyethylacrylate copolymer, or a combination thereof.
  • the acrylamide-based copolymer may further include one or more non-acrylic monomers.
  • the acrylamide-based copolymer may further improve the heat resistance of the copolymer and the bonding strength to the porous substrate of the separation membrane.
  • the non-acrylic monomer may be used without particular limitation as long as it is a copolymerizable monomer other than the above-mentioned acrylic monomer.
  • the copolymerizable non-acrylic monomer include vinyl esters, nitrogen-containing heterocyclic monomers, N-vinylcarboxylic acid amides, lactam monomers, olefin monomers, vinyl ether monomers, aromatic vinyl compounds, olefins or dienes, vinyl ethers, vinyl chloride, sulfonic acid group-containing monomers, imide group-containing monomers, isocyanate group-containing monomers, etc., and at least one of these may be selected.
  • non-acrylic monomers include vinyl esters such as vinyl acetate and vinyl propionate; N-Vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloyl piperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-
  • the content of the non-acrylic monomer included in the acrylamide copolymer is not particularly limited and can be used within a range that does not hinder the aqueous crosslinking reaction characteristics of the acrylamide copolymer and the high heat resistance characteristics of the membrane.
  • the non-acrylic monomer may be included in a range of 0.1 to 30 mol% based on the total mol of the monomer components constituting the acrylamide copolymer.
  • the content of the acrylamide-based copolymer is 10 to 100 wt%, 30 to 95 wt%, 50 to 90 wt%, or 60 to 80 wt% based on the total weight of the binder. In the above range, a composition for forming an inorganic layer for a separation membrane with improved heat resistance and substrate bonding strength can be provided.
  • the inorganic layer may further include a non-crosslinkable binder.
  • a non-crosslinkable binder By additionally including a non-crosslinkable binder in the inorganic layer, the adhesion to the substrate or electrode and the heat resistance can be further improved.
  • the non-crosslinking binder may be, for example, a single polymer or a mixture thereof selected from the group consisting of polyvinylidene fluoride (PVdF)-based polymers, polymethyl methacrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinylacetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxyl methyl cellulose, and acrylonitrile-butadiene-styrene copolymers.
  • the non-crosslinking binder may be, for example, a vinylidene fluoride-based polymer.
  • the above vinylidene fluoride-based polymer may be, for example, polyvinylidene fluoride, a vinylidene fluoride copolymer, or a mixture thereof.
  • the vinylidene fluoride copolymer refers to a polymer that contains 5 wt% or less of a type of repeating unit other than a vinylidene fluoride repeating unit.
  • the vinylidene fluoride copolymer may be, for example, a vinylidene fluoride-hexafluoropropylene copolymer.
  • the weight ratio of the crosslinkable structure binder and the non-crosslinkable binder may be 8:2 to 2:8, specifically 3:7 to 7:3.
  • the non-crosslinkable binder is used in the above-described range, a separator with improved adhesive strength and heat resistance can be manufactured.
  • the thickness of the porous substrate is, for example, 1 ⁇ m to 100 ⁇ m, 1 to 40 ⁇ m, 1 ⁇ m to 30 ⁇ m, 5 ⁇ m to 20 ⁇ m, 5 ⁇ m to 15 ⁇ m, or 5 ⁇ m to 10 ⁇ m. In the present disclosure, the thickness represents an average thickness.
  • a separator having an appropriate thickness that is thick enough to prevent short-circuiting between the positive and negative electrodes of the battery, but not so thick as to increase the internal resistance of the battery, can be manufactured.
  • the porosity of the porous substrate included in the separation membrane may be 5% to 95%, 30% to 80%, for example, 40% to 60%, and the air permeability may be 250 sec/100cc or less, 230 sec/100cc or less, 210 sec/100cc or less, 200 sec/100cc or less, 180 sec/100cc or less, or 150 sec/100cc or less.
  • the pore size of the porous substrate in the separation membrane may be 0.01 ⁇ m to 50 ⁇ m, 0.01 ⁇ m to 30 ⁇ m, 0.01 ⁇ m to 20 ⁇ m, or 0.01 ⁇ m to 10 ⁇ m. In the present disclosure, the pore size represents an average pore size.
  • the porous substrate may be, but is not limited to, a polymer film formed of any one polymer selected from the group consisting of polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ether ketone, polyarylether ketone, polyetherimide, polyamideimide, polybenzimidazole, polyether sulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylene sulfide, and polyethylene naphthalate, or a mixture of two or more thereof.
  • polyolefins such as polyethylene and polypropylene
  • polyesters such as polyethylene terephthalate and polybutylene terephthalate
  • polyacetal polyamide, polyimide, polycarbonate, polyether ether ketone, polyarylether ketone, polyetherimide, polyamideimide
  • the porous substrate may be a polyolefin-based substrate, and the polyolefin-based substrate may have an excellent shut down function, thereby contributing to improved safety of the battery.
  • the polyolefin-based substrate may be selected from the group consisting of, for example, a polyethylene single film, a polypropylene single film, a polyethylene/polypropylene bilayer film, a polypropylene/polyethylene/polypropylene triple film, and a polyethylene/polypropylene/polyethylene triple film.
  • the polyolefin-based resin may include a non-olefin resin in addition to an olefin resin, or may include a copolymer of an olefin and a non-olefin monomer.
  • the method for manufacturing a separation membrane according to the embodiment of the present invention can be any method that can be used in the relevant technical field.
  • the method can be manufactured by manufacturing a slurry containing inorganic particles, a first binder, and optionally inorganic particles, applying the slurry onto a porous substrate, and then drying and rolling the slurry.
  • the method of applying the above slurry is not particularly limited, and any method that can be used in the relevant technical field may be used.
  • it may be formed by methods such as printing, compression, indentation, roller application, blade application, grinding application, dipping application, spray application, or flow application.
  • pretreatment such as sulfonation treatment, grafting treatment, corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, or sputter etching treatment may be optionally performed to improve adhesion with the adhesive layer.
  • the adhesive strength with the porous substrate may be 0.5 N/mm or more, 0.7 N/mm or more, 0.8 N/mm or more, specifically 0.8 to 0.99 N/mm, for example 0.81 to 0.93 N/mm.
  • the substrate adhesive strength is in the above range, the adhesive strength between the adhesive layer and the porous substrate is excellent, so that the performance of the battery can be maintained for a long period of time.
  • the method for measuring the substrate adhesive strength is not particularly limited, and a method commonly used in the technical field of the present invention can be used.
  • a non-limiting example of a method for measuring the substrate adhesion of the separator is as follows: According to Korean Industrial Standard KS-A-01107 (Testing method for adhesive tapes and adhesive sheets), the separator is cut to a width of 25 mm and a length of 250 mm, tape (nitto 31B) is attached to both sides to make a specimen, and then the specimen is compressed by reciprocating once at a speed of 300 mm/min using a compression roller with a load of 2 kg.
  • the specimen is flipped 180° and approximately 25 mm is peeled off, and the separator and the tape attached to one side of the separator are fixed to the upper clip of a tensile strength tester (Instron Series 1X/s Automated Materials Tester-3343, Instron).
  • the tape attached to the other side of the separator is fixed to the lower clip and pulled at a tensile speed of 60 mm/min to measure the pressure when the porous adhesive layer is peeled off from the porous substrate, thereby obtaining the substrate adhesion.
  • the above separator may have an anode adhesion of 0.5 gf/5mm or more and an cathode adhesion of 0.1 gf/5mm or more.
  • the anode adhesion may be 0.8 gf/5mm or more and the cathode adhesion may be 0.2 gf/5mm or more.
  • the separator is sufficiently adhered to the anode and the cathode, and thus, in an environment where expansion and contraction of the battery are repeated due to repeated charging and discharging of the battery including the above separator, changes in the shape of the battery can be minimized, and a short ion transfer distance can be secured, thereby improving the output efficiency of the battery.
  • a secondary battery which includes: a cathode; a separator according to one embodiment, positioned between the cathode and the anode; and an electrolyte.
  • the secondary battery may be 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.
  • 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 a secondary battery according to the present invention is not particularly limited, and a method commonly used in the technical field of the present invention can be used.
  • An inorganic layer is provided on top of a porous substrate.
  • a coating method for forming the inorganic layer, a coating method, lamination, coextrusion, etc. can be used.
  • Non-limiting examples of the coating method include, but are not necessarily limited to, roll coating, spin coating, dip coating, flow coating, spray coating, etc.
  • the above inorganic layer can be cured by providing a composition for forming an inorganic layer on top of a porous substrate and then applying light or heat thereto.
  • the photocuring can be specifically ultraviolet curing or far-infrared curing, and for example, ultraviolet curing.
  • the photocuring can include irradiating the porous heat-resistant layer with a light amount of, for example, 500 mJ/cm 2 to 3000 mJ/cm 2 , specifically, a light amount of 500 mJ/cm 2 to 2000 mJ/cm 2 .
  • the irradiation time can be 1 minute to 15 hours.
  • a homogeneous curing density can be obtained through a subsequent heat treatment after the photocuring, and this can be performed at a temperature of about 50° C. or higher and about 180° C. or lower for 1 hour to 10 hours. Additionally, in the case of heat curing, it may include curing at about 40°C to 120°C, 50°C to 100°C, or 60 to 90°C for 1 hour to 36 hours, specifically, curing for about 5 hours to 24 hours.
  • the composition for forming the above inorganic layer may include a material for forming the crosslinking binder and/or a polymerization initiator for crosslinking the crosslinking binder and the surface-treated inorganic particles.
  • the above polymerization initiator acts as a curing agent that generates free radicals by heating or light, and can be appropriately selected depending on the type of functional group of the material and inorganic particles that generate the crosslinked structure binder.
  • the initiator may be a thermal polymerization initiator such as a peroxide type, an azo type, an amine type, an imidazole type, or an isocyanate type, or a photopolymerization initiator such as an onium salt or an organometallic salt.
  • an adhesive layer composition containing first particles, second particles, and a solvent, which are organic binders, is coated and dried on top of the inorganic layer to form an adhesive layer.
  • the composition for forming the first coating layer can further include an organic solvent as long as it does not impair the aqueous characteristics.
  • the organic solvent can be an alcohol-based organic solvent.
  • the organic solvent can include one or more alcohol-based organic solvents selected from the group consisting of methanol, ethanol, propanol, and butanol.
  • water and the organic solvent can be included in a volume ratio of 100:0 to 60:40, a volume ratio of 95:5 to 80:20, or a volume ratio of 85:15 to 70:30.
  • a composition for forming the first coating layer of a separator with improved drying characteristics can be provided.
  • the solvent is evaporated through drying after coating the composition for forming the first coating layer of the separator, and thus does not exist in the coating layer of the final obtained separator.
  • the coating method is not particularly limited, and for example, one or more selected from a forward roll coating method, a reverse roll coating method, a microgravure coating method, and a direct metering coating method may be selected, but is not necessarily limited to these methods.
  • the coating method may be, for example, a direct metering coating method.
  • the above drying can be carried out by hot air in a dryer.
  • the drying can be carried out, for example, at 30 to 80°C, 35 to 75°C, 40 to 70°C, or 45 to 65°C.
  • a separator having improved bending strength and peel strength can be manufactured.
  • a secondary battery according to another embodiment includes a cathode, an anode, and the above-described separator disposed between the cathode and the anode.
  • the secondary battery is, for example, a lithium secondary battery.
  • a secondary battery includes an electrode assembly including a cathode, an anode, and the above-described separator disposed between the cathode and the anode, and the electrode assembly may have a form in which the electrode assembly is wound in a jellyroll shape. Since the lithium battery includes the above-described separator, the adhesive force between the electrodes (cathode and anode) and the separator increases, so that the volume change during charge and discharge of the lithium battery can be suppressed. Accordingly, deterioration of the lithium battery accompanying the volume change of the lithium secondary battery can be suppressed, so that the life characteristics of the lithium battery can be improved.
  • Lithium secondary batteries can be manufactured, for example, by the following methods.
  • a negative electrode active material composition is prepared by mixing a negative electrode active material, a conductive agent, a binder, and a solvent.
  • the negative electrode active material composition is directly coated on a metal current collector to manufacture a negative electrode plate.
  • the negative electrode active material composition may be cast on a separate support, and then a film peeled off from the support may be laminated on a metal current collector to manufacture a negative electrode plate.
  • the negative electrode is not limited to the forms listed above and may have forms other than the above forms.
  • the negative active material includes a carbon-based material.
  • the carbonaceous material can be crystalline carbon, amorphous carbon or a mixture thereof.
  • the crystalline carbon can be non-shaped, plate-shaped, flake-shaped, natural graphite, artificial graphite, graphene, carbon black, fullerene soot or a combination thereof.
  • Natural graphite is naturally occurring graphite, including flake graphite, highly crystalline graphite, and microcrystalline or cryptocrystalline (amorphous) graphite.
  • Artificial graphite is artificially synthesized graphite, made by heating amorphous carbon to high temperatures, and includes primary or electrographite, secondary graphite, and graphite fibers.
  • Expanded graphite is graphite that has had its molecular structure expanded into vertical layers by intercalating chemicals such as acid or alkali between the layers and heating.
  • Graphene contains a single layer or multiple single layers of graphite.
  • Carbon black is a crystalline substance with less regularity than graphite, and can be converted into graphite when heated at about 3,000°C for a long time.
  • Fullerene soot is a carbon mixture containing at least 3 wt% of fullerene, a polyhedral bundle-shaped compound consisting of 60 or more carbon atoms.
  • the above crystalline carbon may have a spherical, plate-like, fibrous, tubular or powder form.
  • the amorphous carbon may be soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, calcined coke, polymer carbide, or a combination thereof.
  • the negative electrode active material may further include a non-carbonaceous material.
  • the negative electrode active material may include at least one selected from the group consisting of a metal capable of forming an alloy with lithium, an alloy of a metal capable of forming an alloy with lithium, and an oxide of a metal capable of forming an alloy with lithium.
  • the metal that can be alloyed with the lithium may be Si, Sn, Al, Ge, Pb, Bi, Sb, a Si-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, a rare earth element or a combination thereof, and is not Si), a Sn-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, a rare earth element or a combination thereof, and is not Sn), etc.
  • Si-Y alloy wherein Y is an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, a rare earth element or a combination thereof, and is not Si
  • Sn-Y alloy wherein Y is an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, a rare earth element or a combination thereof, and is not Sn
  • the element Y can be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.
  • the transition metal oxide may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, or the like.
  • the non-transition metal oxide may be SnO 2 , SiO x (0 ⁇ x ⁇ 2), etc.
  • the negative electrode active material may be at least one selected from the group consisting of Si, Sn, Pb, Ge, Al, SiOx(0 ⁇ x ⁇ 2), SnOy(0 ⁇ y ⁇ 2), Li 4 Ti 5 O 12 , TiO 2 , LiTiO 3 , and Li 2 Ti 3 O 7 , but is not necessarily limited thereto, and any non-carbon negative electrode active material used in the relevant technical field may be used.
  • the negative active material may be a mixture of the above-described carbon-based material and non-carbon-based material, or a composite containing the above-described carbon-based material and non-carbon-based material.
  • the conductive material acetylene black, Ketjen black, natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powders such as copper, nickel, aluminum, and silver, metal fibers, etc. may be used, and further, one or more types of conductive materials such as polyphenylene derivatives may be used in combination, but are not limited thereto, and any material that can be used as a conductive material in the relevant technical field may be used.
  • the above-described crystalline carbon-based material may be added as a conductive material.
  • Binders may include, but are not limited to, vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene, styrene butadiene rubber-based polymers, or combinations thereof, and any binder that can be used in the art may be used.
  • PVDF polyvinylidene fluoride
  • the solvent that can be used is N-methylpyrrolidone, acetone, water, etc., but is not limited thereto, and any solvent that can be used in the relevant technical field can be used.
  • the contents of the negative active material, conductive material, binder and solvent are at levels typically used in lithium batteries. Depending on the purpose and configuration of the lithium battery, one or more of the conductive material, binder and solvent may be omitted.
  • the binder used in manufacturing the cathode may be the same as the coating composition included in the adhesive layer of the separator.
  • a cathode active material composition is prepared by mixing a cathode active material, a conductive agent, a binder, and a solvent.
  • the cathode active material composition is directly coated and dried on a metal current collector to manufacture a cathode plate.
  • the cathode active material composition may be cast on a separate support, and then a film peeled off from the support may be laminated on a metal current collector to manufacture a cathode plate.
  • the cathode active material may include at least one selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide, but is not necessarily limited thereto, and any cathode active material available in the art may be used.
  • Li a A 1-b B b D 2 (in the above formula, 0.90 ⁇ a ⁇ 1.8, and 0 ⁇ b ⁇ 0.5); Li a E 1-b B b O 2-c D c (in the above formula, 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); LiE 2-b B b O 4-c D c (in the above formula, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); Li a Ni 1-bc Co b B c D ⁇ (in the above formula, 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05, 0 ⁇ ⁇ ⁇ 2); Li a Ni 1-bc Co b B c O 2- ⁇ F ⁇ (in the above formula, 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ ⁇
  • A is Ni, Co, Mn, or a combination thereof
  • B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof
  • D is O, F, S, P, or a combination thereof
  • E is Co, Mn, or a combination thereof
  • F is F, S, P, or a combination thereof
  • G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof
  • Q is Ti, Mo, Mn, or a combination thereof
  • I is Cr, V, Fe, Sc, Y, or a combination thereof
  • J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.
  • the coating layer may include a coating element compound of an oxide, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element of the coating element.
  • the compounds forming these coating layers may be amorphous or crystalline.
  • the coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof.
  • the coating layer forming process may use any coating method as long as it can coat the compound with these elements by a method (for example, spray coating, dipping, etc.) that does not adversely affect the properties of the positive electrode active material, and since this is well understood by those engaged in the relevant field, a detailed description thereof will be omitted.
  • the conductive agent, binder and solvent may be the same as those used in the negative electrode active material composition. Meanwhile, it is also possible to form pores inside the electrode plate by further adding a plasticizer to the positive electrode active material composition and/or the negative electrode active material composition.
  • the contents of the cathode active material, conductive agent, general binder and solvent are at levels typically used in lithium batteries. Depending on the purpose and configuration of the lithium battery, one or more of the conductive agent, general binder and solvent may be omitted.
  • the binder used in the manufacture of the anode may be the same as the adhesive layer composition included in the adhesive layer of the separator.
  • a separator disposed between the anode and the cathode includes a porous substrate as described above; and an adhesive layer disposed on both sides of the porous substrate, wherein the adhesive layer includes the coating composition for a separator as described above.
  • the separator may be prepared separately and placed between the positive electrode and the negative electrode.
  • the separator may be prepared by winding an electrode assembly including the positive electrode/separator/negative electrode into a jellyroll shape, accommodating the jellyroll in a battery case or pouch, thermally softening the jellyroll under pressure and performing an initial charge (pre-charging) while accommodated in the battery case or pouch, hot-rolling the charged jellyroll, cold-rolling the charged jellyroll, and charging/discharging the charged jellyroll under pressure.
  • the electrolyte can be in a liquid or gel state.
  • the electrolyte may be an organic electrolyte.
  • the electrolyte may be a solid.
  • it may be boron oxide, lithium oxynitride, etc., but is not limited thereto, and any solid electrolyte that can be used in the relevant technical field may be used.
  • the solid electrolyte may be formed on the cathode by a method such as sputtering.
  • an organic electrolyte can be prepared.
  • the organic electrolyte can be manufactured by dissolving a lithium salt in an organic solvent.
  • organic solvent that can be used as an organic solvent in the relevant technical field can be used.
  • any lithium salt that can be used as a lithium salt in the relevant technical field can be used.
  • a square lithium secondary battery is exemplarily described.
  • Fig. 4 is an exploded perspective view of a lithium battery according to one embodiment.
  • a lithium secondary battery (100) includes an electrode assembly (160) wound with a separator (110) according to one embodiment interposed between a positive electrode (140) and a negative electrode (150) and a case (170) in which the electrode assembly (160) is built.
  • the electrode assembly (160) may be, for example, in the form of a jelly roll formed by winding an anode (140) and a cathode (150) with a separator (110) in between.
  • the anode (140), cathode (150), and separator (110) are impregnated with an electrolyte (not shown).
  • the above lithium secondary battery may be a lithium ion battery.
  • the above lithium battery may be a lithium polymer battery.
  • Lithium batteries are suitable for electric vehicles (EVs) because they have excellent high-rate characteristics and life characteristics.
  • EVs electric vehicles
  • PHEVs plug-in hybrid electric vehicles
  • the reaction was carried out for 12 hours while controlling the temperature of the reaction solution to be stable between 65 °C and 70 °C. After cooling to room temperature, the pH of the reaction solution was adjusted to 7 to 8 using a 25% ammonia aqueous solution. In this way, poly(acrylic acid-co-acrylamide-co-2-acrylamido-2-methylpropanesulfonic acid), an acrylic copolymer, was prepared. The molar ratio of acrylic acid, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid was 10:85:5. About 10 mL of the reaction solution (reaction product) was taken, and the nonvolatile component was measured, which was 9.5 wt% (theoretical value: 10 wt%).
  • Example 1 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • boehmite (Nabaltec, Japan) having an average size of 300 nm was pulverized for 2 hours using a bead mill, and then an inorganic dispersion containing 40 wt% of the pulverized boehmite (70 wt% of water) was obtained.
  • an acrylic copolymer manufactured according to Manufacturing Example 1 was mixed so that the boehmite weight ratio was 95%, and water was added so that the total solid content was 25 wt%, thereby forming a composition for forming an inorganic layer.
  • the above-mentioned manufactured inorganic layer composition was coated on the cross-section of a polyethylene single-layer substrate film having a thickness of 5.5 ⁇ m used as a porous substrate by a gravure coating method, and then dried for 10 seconds under conditions of a drying temperature of 70°C and a wind speed of 15 m/sec, thereby manufacturing a separation membrane having an inorganic layer having a coating thickness of 2 ⁇ m.
  • the first particle, poly(butylmethacrylate-co-ethyleneglycol dimethacrylate) copolymer (2550M, Zeon Co., Ltd.) and the second particle, poly(styrene-co-ethylhexylacrylate-acrylonitrile) copolymer (SP-18 A, Zeon Co., Ltd.) were mixed at a weight ratio of 5.13:1, and then a PAA compound (AQC, Sumittomo Co., Ltd.) was added and mixed thereto to form a composition for forming an adhesive layer.
  • the content of the PAA compound is about 2 wt% based on 100 wt% of the total weight of the composition for forming an adhesive layer.
  • the mixing molar ratio of butyl methacrylate and ethylene glycol dimethacrylate is 8:2
  • the mixing molar ratio of styrene, ethylhexylacrylate, and acrylonitrile is 8:5:0.1.
  • the porous substrate of the separation membrane having the inorganic layer (thickness: 2 ⁇ m) manufactured according to the above process was coated with the coating composition for forming the adhesive layer using the gravure coating method, and the coating was dried for 10 seconds under conditions of a drying temperature of 60°C and a wind speed of 15 m/sec, thereby forming a 1.0 g/ m2 (double-sided) adhesive layer on the inorganic layer, thereby forming the separation membrane.
  • An inorganic layer and an adhesive layer were formed on the other side of the porous substrate according to the method described above, respectively, to manufacture a separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer.
  • Example 2 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • the first particle Poly(butylmethacrylate-co-ethyleneglycol dimethacrylate) copolymer (2550M, Zeon Co.)
  • the second particle Poly(styrene-co-ethylhexylacrylate-acrylonitrile) structured copolymer (SP-18 B, Zeon Co.) with a size of 780 nm, were mixed at a weight ratio of 1.97:1, and then a PAA compound (AQC, Sumittomo Co.) was used at 2 wt% of the total weight ratio to form a composition for forming an adhesive layer.
  • the application of the adhesive layer coating layer was performed in the same manner as in Example 1 to manufacture a separator.
  • Example 3 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • the first particle Poly(butylmethacrylate-co-ethyleneglycol dimethacrylate) copolymer (2550M, Zeon Co.), and the second particle, Poly(styrene-co-ethylhexylacrylate-acrylonitrile) copolymer (SP-18 A, Zeon Co.), were mixed at a weight ratio of 1.97:1, and then a PAA compound (AQC, Sumittomo Co.) was used at 2 wt% of the total weight ratio to form a composition for forming an adhesive layer.
  • AQC Sumittomo Co.
  • Example 4 Separator having a laminated structure of adhesive layer/porous substrate/inorganic layer/adhesive layer
  • a composition for forming an adhesive layer was prepared according to the conditions described in Table 1 below, and the composition for forming an adhesive layer was coated and dried on the other side of a porous substrate on which an inorganic layer and an adhesive layer were sequentially formed, thereby forming an adhesive layer on the other side of the porous substrate, thereby forming a separator in the same manner as in Example 1, except that the composition for forming an adhesive layer was coated and dried on the other side of the porous substrate.
  • the laminated structure of this separator had a laminated structure of adhesive layer/porous substrate/inorganic layer/adhesive layer.
  • Comparative Example 1 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • a composition for forming an adhesive layer was formed using 2 wt% of a PAA compound (AQC, Sumitomo Co., Ltd.) based on the total weight of the first particle, Poly(butylmethacrylate-co-ethyleneglycol dimethacrylate) copolymer (2550M, Zeon Co., Ltd.). Coating and drying of the composition for forming an adhesive layer were performed in the same manner as in Example 1 to manufacture a separator.
  • a PAA compound AQC, Sumitomo Co., Ltd.
  • Poly(butylmethacrylate-co-ethyleneglycol dimethacrylate) copolymer 2550M, Zeon Co., Ltd.
  • Comparative Example 2 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • a composition for forming an adhesive layer was prepared by applying 2 wt% of a PAA compound (AQC, Sumittomo Co., Ltd.) to a copolymer (SP-18 A, Zeon Co., Ltd.) having a poly(styrene-co-ethylhexylacrylate) structure and a size of 500 nm as the second particle based on the total weight of the copolymer. Coating and drying of the composition for forming an adhesive layer were performed in the same manner as in Example 1 to prepare a separator.
  • a PAA compound AQC, Sumittomo Co., Ltd.
  • SP-18 A Zeon Co., Ltd.
  • Coating and drying of the composition for forming an adhesive layer were performed in the same manner as in Example 1 to prepare a separator.
  • Comparative Example 3 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • the first particle Poly(butylmethacrylate-co-ethyleneglycol dimethacrylate) copolymer (2550M, Zeon Co.)
  • the second particle Poly(styrene-co-ethylhexylacrylate-acrylonitrile) structured copolymer (SP-18 C, Zeon Co.), having a size of 870 nm, were mixed in a weight ratio of 1.97:1, and then a PAA compound (AQC, Sumittomo Co.) was used at 2 wt% of the total weight ratio to prepare a composition for forming an adhesive layer.
  • the coating and drying of the composition for forming an adhesive layer were performed in the same manner as in Example 1 to prepare a separator.
  • Comparative Example 4 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • a membrane was manufactured in the same manner as in Example 1, except that the volume ratio of the first particle, the organic filler, and the second particle, the adhesive binder, was changed to 8:1.
  • Comparative Example 5 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • An adhesive layer and a separator including the same were manufactured in the same manner as in Example 1, except that the mixing volume ratio of the first particles and the second particles was changed to 1:4 when manufacturing a composition for forming an adhesive layer.
  • Comparative Example 6 Separator having a laminated structure of adhesive layer/inorganic layer/porous substrate/inorganic layer/adhesive layer
  • An adhesive layer and a separator including the same were manufactured in the same manner as in Example 1, except that the mixing volume ratio of the first particles and the second particles was changed to 9:1 when manufacturing a composition for forming an adhesive layer.
  • SP-18 A (Zeon) is used as an organic adhesive binder (500 nm), and is a copolymer having a poly(styrene-co-ethylhexylacrylate-acrylonitrile) structure, and the mixing molar ratio of styrene, ethylhexylacrylate, and acrylonitrile is 8:2:0.5.
  • SP-18 C (Zeon) is used as an organic adhesive binder (870 nm), and is a copolymer having a poly(styrene-co-ethylhexylacrylate-acrylonitrile) structure, and the mixing molar ratio of styrene, ethylhexylacrylate, and acrylonitrile is 8:2:0.5.
  • AQC (sumittomo) is used as a compound containing PAA, and its weight average molecular weight is about 450,000, and the size of each particle in Table 1 represents D50.
  • the numbers of the first particle, the second particle, and other in the composition of Table 1 represent weight parts.
  • the cathode was manufactured according to the following process.
  • a slurry of a negative electrode active material was prepared by mixing 97 wt% of graphite particles having an average particle size of 25 ⁇ m, 1.5 wt% of styrene-butadiene rubber (SBR) binder, and 1.5 wt% of carboxymethyl cellulose (CMC), placing the mixture in distilled water, and stirring the mixture for 60 minutes using a mechanical stirrer.
  • the slurry was applied onto a 10 ⁇ m thick copper current collector using a doctor blade, dried in a hot air dryer at 100°C for 0.5 hour, dried again under vacuum at 120°C for 4 hours, and then roll pressing to prepare a negative electrode.
  • the anode was manufactured according to the following process.
  • LiCoO 2 97 wt%, carbon black powder 1.5 wt% as a conductive material, and polyvinylidene fluoride (PVdF) 1.5 wt% were mixed and placed in an N-methyl-2-pyrrolidone solvent, and stirred for 30 minutes using a mechanical stirrer to prepare a cathode active material slurry.
  • the slurry was applied onto a 20 ⁇ m thick aluminum current collector using a doctor blade, dried in a hot air dryer at 100°C for 0.5 hour, dried again under vacuum at 120°C for 4 hours, and then rolled to prepare a cathode.
  • An electrode assembly jelly roll was prepared by interposing a separator obtained according to Example 1 between the positive and negative electrodes manufactured above and then winding the membrane.
  • the jelly roll was inserted into a pouch, an electrolyte was injected, and the pouch was vacuum-sealed.
  • the electrolyte used was 1.3 M LiPF 6 dissolved in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 3:5:2.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • a lithium battery was manufactured by pressing a jelly roll inserted into a pouch at a temperature of 80°C for 3 minutes while applying a pressure of 11.7 kgf/cm 2 .
  • a lithium battery was manufactured in the same manner as in Manufacturing Example 1, except that the separator of Examples 2 to 4 was used instead of the separator of Example 1.
  • a lithium battery was manufactured in the same manner as in Manufacturing Example 1, except that the separator of Comparative Examples 1-6 was used instead of the separator of Example 1.
  • the unit thickness of each membrane was measured using an air permeation tester (Asahi Seiko OKEN Type Air Permeation Tester: EGO1-55-1MR) according to the following method.
  • measurement pressure 0.05 mPa
  • cylinder pressure 2.5 kg/cm2
  • setting time 10 seconds
  • measurements were made more than 10 times at 10 cm intervals for a 1 m specimen, and the average of the data was recorded.
  • Air permeability (sec/100cc) represents the change in air permeability, which is expressed by the following formula.
  • Air permeability (membrane air permeability after test) - (initial membrane air permeability).
  • the ventilation test conditions are as follows.
  • the bending strength of the lithium batteries manufactured according to Manufacturing Examples 1 to 5 and Comparative Manufacturing Examples 1 to 6 was measured to investigate the bending strength of the pouch-type battery.
  • the bending strength was measured using the 3-point bending method to measure the adhesive strength (bending strength) between the active material layer of the positive electrode and the separator in each lithium battery.
  • the first charge/discharge cycle was performed by constant current charging at a current of 0.1 C until the voltage reached 4.4 V, followed by constant voltage charging at a current of 0.05 C. After the charging was completed, the cell was rested for about 10 minutes and then constant current discharged at a current of 0.1 C until the voltage reached 3 V.
  • the second charge/discharge cycle was performed by constant current charging at a current of 0.2 C until the voltage reached 4.2 V, followed by constant voltage charging at a current of 0.05 C. After the charging was completed, the cell was rested for about 10 minutes and then constant current discharged at a current of 0.2 C until the voltage reached 3 V.
  • the life evaluation was performed by constant current charging until the voltage reached 4.4 V at a current of 1C, and then constant voltage charging until the voltage reached 0.05C. After the charging was completed, the cell was rested for approximately 10 minutes, and then constant current discharge was performed until the voltage reached 3 V at a current of 1C. This cycle was repeated 500 times to evaluate the life characteristics.
  • the life span is evaluated according to Equation 2 below.
  • Lifespan (500 discharge capacity / 1 discharge capacity) X 100
  • the test was conducted using an Instron universal testing machine according to Korean Industrial Standard KS-A-01107 (Testing method for adhesive tapes and adhesive sheets).
  • Each of the separators manufactured in the above examples and comparative examples was cut to a width of 25 mm and a length of 250 mm, and tape (nitto 31B) was attached to both sides to make a specimen, and then the specimen was compressed by reciprocating once at a speed of 300 mm/min using a compression roller with a load of 2 kg.
  • the specimen was turned over 180°, about 25 mm was peeled off, and the separator and the tape attached to one side of the separator were fixed to the upper clip of a tensile strength tester (Instron Series 1X/s Automated Materials Tester-3343, Instron).
  • the tape attached to the other side of the separator was fixed to the lower clip, and then the pressure when the porous adhesive layer was peeled off from the porous substrate was measured by pulling at a tensile speed of 60 mm/min.
  • the separator of Comparative Example 1 has excellent membrane resistance, but its bending strength and substrate bonding strength are poor, making it difficult to apply practically, and the life characteristics of a lithium battery employing such a separator are significantly deteriorated compared to Examples 1 to 4.
  • the separator of Comparative Example 2 has excellent bending strength and substrate bonding strength, but not only does it exhibit poor membrane resistance, but the life characteristics of a lithium battery employing such a separator are significantly deteriorated compared to Examples 1 to 4.
  • the separator of Comparative Example 3 has a lower lifespan and higher air permeability compared to the examples, and the separator of Comparative Example 4 has poor adhesion to the substrate, making it difficult to describe a strong bonding force between the electrode and the adhesive layer.
  • the separator of Comparative Example 5 has a low bending strength, resulting in a lower lifespan and higher air permeability compared to the examples, and the separator of Comparative Example 6 has poor membrane resistance characteristics, and the lifespan characteristics of a lithium battery employing it are very poor, making it difficult to apply practically. From these results, it was found that by controlling the volume ratio of the first particles and the second particles in the adhesive layer of the separators of Examples 1 to 4, the adhesive strength between the electrode and the separator can be strongly controlled, thereby manufacturing a lithium battery with improved lifespan characteristics.

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Abstract

L'invention concerne un séparateur pour une batterie secondaire, et une batterie secondaire le comprenant, le séparateur comprenant un substrat poreux, une couche inorganique positionnée sur au moins une surface du substrat poreux, et une couche adhésive positionnée sur la couche inorganique, la couche adhésive contenant des premières particules et des secondes particules qui sont un liant organique de différentes tailles de particules, et le rapport de volume de mélange des premières particules et des secondes particules étant de 1 : 5 à 1 : 35.
PCT/KR2024/003562 2023-03-26 2024-03-21 Séparateur pour batterie secondaire et batterie secondaire le comprenant Ceased WO2024205129A1 (fr)

Applications Claiming Priority (4)

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KR10-2023-0039341 2023-03-26
KR20230039341 2023-03-26
KR1020230056577A KR20240144806A (ko) 2023-03-26 2023-04-28 이차전지용 분리막 및 이를 포함하는 이차전지
KR10-2023-0056577 2023-04-28

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190097531A (ko) * 2018-02-12 2019-08-21 삼성에스디아이 주식회사 리튬이차전지용 분리막 및 이를 포함하는 리튬이차전지
KR20220018951A (ko) * 2020-08-07 2022-02-15 주식회사 엘지에너지솔루션 이차전지용 분리막 및 이를 포함하는 이차전지
KR20220070098A (ko) * 2020-11-20 2022-05-30 더블유스코프코리아 주식회사 전극 접착층을 가지는 분리막 및 이를 포함하는 전기화학소자
KR20230031807A (ko) * 2021-08-27 2023-03-07 주식회사 엘지에너지솔루션 전기화학소자용 분리막, 이를 포함하는 전극 조립체 및 전기화학소자
JP2023040938A (ja) * 2021-09-10 2023-03-23 帝人株式会社 非水系二次電池用セパレータ及び非水系二次電池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190097531A (ko) * 2018-02-12 2019-08-21 삼성에스디아이 주식회사 리튬이차전지용 분리막 및 이를 포함하는 리튬이차전지
KR20220018951A (ko) * 2020-08-07 2022-02-15 주식회사 엘지에너지솔루션 이차전지용 분리막 및 이를 포함하는 이차전지
KR20220070098A (ko) * 2020-11-20 2022-05-30 더블유스코프코리아 주식회사 전극 접착층을 가지는 분리막 및 이를 포함하는 전기화학소자
KR20230031807A (ko) * 2021-08-27 2023-03-07 주식회사 엘지에너지솔루션 전기화학소자용 분리막, 이를 포함하는 전극 조립체 및 전기화학소자
JP2023040938A (ja) * 2021-09-10 2023-03-23 帝人株式会社 非水系二次電池用セパレータ及び非水系二次電池

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