WO2022110225A1 - 一种隔离膜、含有它的二次电池及其相关的电池模块、电池包和装置 - Google Patents

一种隔离膜、含有它的二次电池及其相关的电池模块、电池包和装置 Download PDF

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WO2022110225A1
WO2022110225A1 PCT/CN2020/132953 CN2020132953W WO2022110225A1 WO 2022110225 A1 WO2022110225 A1 WO 2022110225A1 CN 2020132953 W CN2020132953 W CN 2020132953W WO 2022110225 A1 WO2022110225 A1 WO 2022110225A1
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Prior art keywords
organic particles
particles
coating
copolymer
separator
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PCT/CN2020/132953
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English (en)
French (fr)
Inventor
兰媛媛
杨建瑞
洪海艺
程丛
柳娜
金海族
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宁德时代新能源科技股份有限公司
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Priority to EP20963113.4A priority Critical patent/EP4071919A4/en
Priority to PCT/CN2020/132953 priority patent/WO2022110225A1/zh
Priority to CN202080103004.6A priority patent/CN115803960A/zh
Publication of WO2022110225A1 publication Critical patent/WO2022110225A1/zh
Priority to US18/114,164 priority patent/US20230207963A1/en
Priority to US18/624,235 priority patent/US20240266673A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—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
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426—Fluorocarbon polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • H01M50/489—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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/494—Tensile strength
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of secondary batteries, and in particular, to a separator, a secondary battery containing the same, and related battery modules, battery packs and devices.
  • the present application provides a separator, which aims to enable the secondary battery containing the separator to have both good cycle performance and safety performance at the same time.
  • a first aspect of the present application provides a separator, which includes: a base material and a coating layer disposed on at least one surface of the base material.
  • the coating includes organic particles and inorganic particles.
  • the organic particles include first-type organic particles, the inorganic particles form an inorganic particle layer, the first-type organic particles are embedded in the inorganic particle layer and form protrusions on the surface of the inorganic particle layer.
  • the number-average particle size of the first organic particles is greater than or equal to 12 ⁇ m.
  • the ratio of the average height of the protrusions to the thickness of the inorganic particle layer is ⁇ 4.
  • the present application at least has the following beneficial effects:
  • the isolation film of the present application contains inorganic particles and the first organic particles in the same coating, and compared with the isolation film having two coatings of the inorganic particle layer and the organic particle layer, the overall thickness of the isolation film is greatly reduced, thereby reducing the overall thickness of the isolation film.
  • the energy density of the battery is improved; and the organic particles and inorganic particles form a special coating structure, which can ensure good adhesion and contact interface between the separator and the electrode sheet, thereby improving the cycle performance of the battery; at the same time, in the When working at high temperature, the separator coating structure can form a glue film structure, which can effectively reduce the ion transport channel and delay the heat spread, thereby further improving the safety performance of the battery.
  • the ratio of the average height of the protrusions to the thickness of the inorganic particle layer is 4-20, optionally 5-15.
  • the ratio of the average height of the protrusions to the thickness of the inorganic particle layer is within the above range, the cycle performance and safety performance of the battery can be further improved.
  • the average height of the protrusions is greater than or equal to 10 ⁇ m, and can be optionally 12 ⁇ m-18 ⁇ m. When the average height of the protrusions is within the above range, the cycle performance and safety performance of the battery can be further improved.
  • the number average particle size of the first organic particles is 15 ⁇ m-25 ⁇ m.
  • the cycle performance and safety performance of the battery can be further improved.
  • the first organic particles are secondary particles.
  • the cycle performance and safety performance of the battery can be further improved.
  • the first organic particle includes a homopolymer or copolymer of fluorine-containing alkenyl monomer units, a homopolymer or copolymer of olefin-based monomer units, and an unsaturated nitrile monomer Homopolymers or copolymers of units, homopolymers or copolymers of alkylene oxide monomer units, and one or more of the modified compounds of the above-mentioned homopolymers or copolymers.
  • the first organic particles comprise polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide , copolymers of different fluoroalkenyl monomer units, copolymers of fluoroalkenyl monomer units and olefinic monomer units, copolymers of fluoroalkenyl monomer units and acrylic monomer units, fluoroolefins A copolymer of a base monomer unit and an acrylate monomer unit, and one or more of the modified compounds of the above-mentioned homopolymers or copolymers.
  • the first organic particles include vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer
  • the separator satisfies at least one of the following (1)-(2):
  • the mass ratio of the first organic particles in the coating is ⁇ 12%, optionally 15%-25%;
  • the mass proportion of the inorganic particles in the coating is ⁇ 85%, and can be selected from 60% to 75%.
  • the cycle performance and safety performance of the battery can be further improved.
  • the organic particles further include second organic particles, the second organic particles are embedded in the inorganic particle layer and form protrusions on the surface of the inorganic particle layer, and the second organic particles are embedded in the inorganic particle layer.
  • the two kinds of organic particles are primary particles.
  • the number-average particle size of the second organic particles is ⁇ 10 ⁇ m, and the number-average particle size of the second organic particles is greater than or equal to 2 ⁇ m; optionally, the second organic particles The number average particle size is 2.5 ⁇ m-6 ⁇ m.
  • the cycle performance and safety performance of the battery can be further improved.
  • the mass ratio of the second organic particles in the coating is 10% or less, and optionally 2% to 10%.
  • the second organic particles include homopolymers or copolymers of acrylic monomer units, homopolymers or copolymers of acrylic monomer units, and styrene monomer units.
  • homopolymers or copolymers One or more of homopolymers or copolymers, polyurethane compounds, rubber compounds, and modified compounds of the above-mentioned homopolymers or copolymers;
  • the second organic particle includes a copolymer of acrylic monomer unit and styrene monomer unit, a copolymer of acrylic monomer unit and styrene monomer unit, acrylic acid Monomer units - acrylate monomer units - copolymers of styrene monomer units, copolymers of styrene monomer units and unsaturated nitrile monomer units, styrene monomer units - olefin monomer units A copolymer of a monomer unit-unsaturated nitrile monomer unit, and one or more of the modified compounds of the above-mentioned copolymer.
  • the second organic particles include butyl acrylate-styrene copolymer, butyl methacrylate-iso-octyl methacrylate copolymer, isooctyl methacrylate-styrene copolymer compound, methacrylate-methacrylic acid-styrene copolymer, methyl acrylate-iso-octyl methacrylate-styrene copolymer, butyl acrylate-iso-octyl acrylate-styrene copolymer, butyl acrylate- Isooctyl Methacrylate-Styrene Copolymer, Butyl Methacrylate-Isooctyl Methacrylate-Styrene Copolymer, Butyl Methacrylate-Isooctyl Acrylate-Styrene Copolymer, Styrene-Prop
  • the thickness of the inorganic particle layer is less than or equal to 5 ⁇ m, and can be optionally 1 ⁇ m to 3 ⁇ m.
  • the cycle performance and safety performance of the battery can be further improved.
  • the volume average particle diameter Dv 50 of the inorganic particles is 0.5 ⁇ m-2.5 ⁇ m, optionally 0.5 ⁇ m-1 ⁇ m.
  • the cycle performance and safety performance of the battery can be further improved.
  • the inorganic particles include boehmite ( ⁇ -AlOOH), alumina (Al 2 O 3 ), barium sulfate (BaSO 4 ), magnesium oxide (MgO), magnesium hydroxide (Mg( OH) 2 ), silicon dioxide (SiO 2 ), tin dioxide (SnO 2 ), titanium oxide (TiO 2 ), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO 2 ), yttrium oxide ( One or more of Y 2 O 3 ), nickel oxide (NiO), cerium oxide (CeO 2 ), zirconium titanate (SrTiO 3 ), barium titanate (BaTiO 3 ), and magnesium fluoride (MgF 2 ).
  • the separator satisfies one or more of the following (1)-(5):
  • the air permeability of the isolation film is 100s/100mL-300s/100mL; optionally, the air permeability of the isolation film is 150s/100mL-250s/100mL;
  • the transverse tensile strength (MD) of the isolation film is 1500kgf/cm 2 -3000kgf/cm 2 ; optionally, the transverse tensile strength of the isolation film is 1800kgf/cm 2 -2500kgf/cm 2 ;
  • the longitudinal tensile strength (TD) of the separator is 1000kgf/cm 2 -2500kgf/cm 2 ; optionally, the longitudinal tensile strength of the separator is 1400kg/cm 2 -2000kg/cm 2 ;
  • the transverse elongation at break of the isolation film is 50%-200%; optionally, the transverse elongation at break of the isolation film is 100%-150%;
  • the longitudinal elongation at break of the separator is 50%-200%; optionally, the longitudinal elongation at break of the separator is 100%-150%.
  • the inorganic particles and the organic particles form a non-uniform pore structure in the coating.
  • the distance between any two adjacent inorganic particles is denoted as L1
  • the distance between any adjacent one inorganic particle and one organic particle is denoted as L2, then L1 ⁇ L2.
  • a second aspect of the present application provides a method for preparing the isolation film of the first aspect, comprising at least the following steps:
  • the coating slurry includes a component material and a solvent, the component material includes organic particles and inorganic particles, and the organic particles include the first organic particles;
  • step (3) coating the coating slurry described in step (2) on at least one side of the substrate described in step (1), forming a coating layer and drying to obtain the isolation film;
  • the isolation film includes: a substrate and a coating disposed on at least one surface of the substrate; the coating includes organic particles and inorganic particles, and the organic particles include first organic particles; the The inorganic particles form an inorganic particle layer, and the first organic particles are embedded in the inorganic particle layer and form protrusions on the surface of the inorganic particle layer; the number average particle size of the first organic particles is ⁇ 12 ⁇ m, and the The ratio of the average height of the protrusions to the thickness of the inorganic particle layer is ⁇ 4.
  • the organic particles further include a second type of organic particles, and the second type of organic particles are embedded in the inorganic particle layer and in the inorganic particle layer Protrusions are formed on the surface, and the second type of organic particles are primary particles.
  • the number-average particle size of the second organic particles is ⁇ 10 ⁇ m, and the number-average particle size of the second organic particles is greater than or equal to 2 ⁇ m; optionally, the second organic particles The number average particle size is 2.5 ⁇ m-6 ⁇ m.
  • the added mass of the second organic particles accounts for less than 10% of the total dry weight of the component materials, and may be optionally 2% to 10%.
  • the method satisfies one or more of the following (1)-(7):
  • the added mass of the first organic particles accounts for more than 12% of the total dry weight of the component materials; optional 12%-30%;
  • the solid content of the coating slurry is 28%-45%, optionally 30%-38%, based on weight;
  • the coating is carried out by a coating machine, and the coating machine includes a gravure roll, and the number of lines of the gravure roll is 100LPI-300LPI, optionally 125LPI-190LPI;
  • the speed of the coating is 30m/min-90m/min, optionally 50m/min-70m/min;
  • the line speed ratio of the coating is 0.8-2.5, optionally 0.8-1.5;
  • the drying temperature is 40°C-70°C, optionally 50°C-60°C;
  • the drying time is 10s-120s, optionally 20s-80s.
  • a third aspect of the present application provides a secondary battery comprising the separator of the first aspect of the present application or the separator prepared according to the method of the second aspect of the present application.
  • a fourth aspect of the present application provides a battery module including the secondary battery of the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack including the battery module of the fourth aspect of the present application.
  • a sixth aspect of the present application provides a device comprising at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, or the battery pack of the fifth aspect of the present application.
  • the secondary battery, battery module, battery pack and device of the present application include the separator provided by the present application, and thus have at least the same advantages as the separator of the present application.
  • 1-1 is a schematic structural diagram of an embodiment of the isolation film of the present application.
  • 1-2 are schematic structural diagrams of another embodiment of the isolation film of the present application.
  • FIG. 2 is a scanning electron microscope (SEM) image of one embodiment of the separator of the present application.
  • CP cross-sectional topography
  • 3-2 is an ion-polished cross-sectional topography (CP) picture of another embodiment of the isolation film of the present application.
  • FIG. 4-1 is a schematic structural diagram of an embodiment of the isolation film of the present application.
  • 4-2 is a schematic structural diagram of another embodiment of the isolation film of the present application.
  • FIG. 5 is a schematic diagram of an embodiment of a secondary battery.
  • FIG. 6 is an exploded view of FIG. 5 .
  • FIG. 7 is a schematic diagram of one embodiment of a battery module.
  • FIG. 8 is a schematic diagram of an embodiment of a battery pack.
  • FIG. 9 is an exploded view of FIG. 8 .
  • FIG. 10 is a schematic diagram of one embodiment of a device in which a secondary battery is used as a power source.
  • any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with any other lower limit to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range.
  • each individually disclosed point or single value may itself serve as a lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
  • the term "or” is inclusive. That is, the phrase “A or (or) B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or present) and B is false (or absent); A is false (or absent) and B is true (or present) ; or both A and B are true (or present).
  • a secondary battery refers to a battery that can continue to be used by activating the active material by charging after the battery is discharged.
  • a secondary battery typically includes a positive electrode, a negative electrode, a separator, and an electrolyte.
  • active ions are inserted and extracted back and forth between the positive electrode and the negative electrode.
  • the separator is arranged between the positive pole piece and the negative pole piece, and plays the role of isolation.
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application provides a release film comprising a substrate and a coating disposed on at least one surface of the substrate.
  • the coating includes organic particles and inorganic particles.
  • the organic particles include first-type organic particles, the inorganic particles form an inorganic particle layer, the first-type organic particles are embedded in the inorganic particle layer and form protrusions on the surface of the inorganic particle layer.
  • the number-average particle size of the first organic particles is greater than or equal to 12 ⁇ m.
  • the ratio of the average height of the protrusions to the thickness of the inorganic particle layer is ⁇ 4.
  • the number-average particle size of the organic particles refers to the arithmetic mean value of the particle size of the organic particles in the separator coating based on the number of organic particles.
  • the particle size of the organic particles refers to the distance between two points on the organic particles that are farthest apart.
  • the isolation film of the present application contains inorganic particles and the first organic particles in the same coating, and compared with the isolation film having two coatings of the inorganic particle layer and the organic particle layer, the overall thickness of the isolation film is greatly reduced, thereby reducing the overall thickness of the isolation film.
  • the energy density of the battery is improved; and the first organic particle is specially designed, so that the battery comprising the separator of the present application has better cycle performance and safety performance.
  • this may be because the inorganic coating of the separator has sufficient non-uniform pores to ensure smooth ion transport channels, and the first organic particles can make the separator and the electrode sheet It has good adhesion and contact interface between the two, which can effectively improve the cycle performance of the battery; at the same time, when working at high temperature, the first organic particles can form a large number of film structures, which can reduce the ion transport channel and delay the heat spread, thereby Get good security performance.
  • the separator includes a substrate (A) and a coating layer (B), and the coating layer (B) includes a first organic particle (B1) and an inorganic particle (B2), the first One organic particle (B1) is a secondary particle, and the first organic particle is embedded in the inorganic particle layer formed by the inorganic particle (B2) and forms protrusions on the surface of the inorganic particle layer.
  • the separator of the present application also optionally satisfies one or more of the following conditions, the performance of the secondary battery comprising the separator of the present application can be further improved. performance.
  • the ratio of the average height of the protrusions to the thickness of the inorganic particle layer is 4-20, optionally 5-15.
  • the cycle performance and safety performance of the battery can be further improved.
  • the inventor has found through a lot of research that when the ratio of the two is too small, it is not conducive to the discharge of gas in the chemical formation process of the battery preparation process. Therefore, the cycle performance of the battery is affected; when the ratio of the two is too large, the ion transmission path may increase, and lithium is easily precipitated on the surface of the negative electrode plate during the battery cycle, thereby affecting the safety performance of the battery.
  • the average height of the protrusions is greater than or equal to 10 ⁇ m, optionally 12 ⁇ m-18 ⁇ m.
  • the average height of the protrusions is within the above range, it can not only provide sufficient bonding force between the separator and the pole piece, but also reduce the risk of wrinkling the separator during the battery preparation process, and effectively reduce the short circuit of the positive and negative electrodes. probability, thereby further improving the safety performance of the battery.
  • the particle size of the first organic particles is 8 ⁇ m-35 ⁇ m.
  • the particle size of the first organic particles is ⁇ 8 ⁇ m, which means that among all the first organic particles used, the particle size of a single first organic particle is ⁇ 8 ⁇ m, such as 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, etc.
  • the number average particle size of the first organic particles is 15 ⁇ m-25 ⁇ m.
  • the particle size distribution of the first organic particles is relatively uniform, and under the precursor to achieve the technical effect of the present application, it is beneficial to form a relatively uniform coating interface.
  • the first organic particles are secondary particles.
  • the first organic particles are secondary particles, it helps to form a uniform coating interface.
  • the separator When the separator is applied to the battery, it can effectively improve the problem of dislocation of the electrodes in the battery preparation process, thereby further improving the safety of the battery. performance.
  • Primary particles refer to particles that do not form an agglomerated state.
  • Secondary particles refer to the agglomerated particles formed by the aggregation of two or more primary particles.
  • the first organic particles may be agglomerated from primary particles having a particle size of 150nm-300nm.
  • the first organic particle comprises a homopolymer or copolymer of fluoroalkenyl monomeric units, a homopolymer or copolymer of olefinic monomeric units, a homopolymer of unsaturated nitrile monomeric units
  • a homopolymer or copolymer of fluoroalkenyl monomeric units a homopolymer or copolymer of olefinic monomeric units
  • a homopolymer of unsaturated nitrile monomeric units One or more of the above mentioned homopolymers or copolymers, homopolymers or copolymers of alkylene oxide monomer units, and modified compounds of the above-mentioned homopolymers or copolymers.
  • the first organic particles comprise polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide , copolymers of different fluoroalkenyl monomer units, copolymers of fluoroalkenyl monomer units and olefinic monomer units, copolymers of fluoroalkenyl monomer units and acrylic monomer units, fluoroolefins A copolymer of a base monomer unit and an acrylate monomer unit, and one or more of the modified compounds of the above-mentioned homopolymers or copolymers.
  • the first organic particle includes vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer
  • the first organic particles are polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and one or more of the modified compounds of the above-mentioned homopolymers or copolymers.
  • the separator satisfies at least one of the following (1)-(2):
  • the mass ratio of the first organic particles in the coating is ⁇ 12%, and can be selected as 15%-25%.
  • the mass proportion of the inorganic particles in the coating is ⁇ 85%, and can be selected from 60% to 75%.
  • the two can play a better synergistic effect, ensuring that the separator has an appropriate uneven pore structure on the premise of ensuring safety performance, and at the same time realizing the lightness of the separator. quality, thereby further improving the energy density of the battery.
  • the organic particles further include a second organic particle, the second organic particle is embedded in the inorganic particle and forms protrusions on the surface of the inorganic particle layer, and the second organic particle is The particles are primary particles.
  • the combination of the first organic particle and the second organic particle can effectively reduce the formation of dense and relatively small organic particles in the coating after being swollen in the electrolyte.
  • the probability of a large adhesive film makes the separator coating have a moderately uneven pore structure, which facilitates the transmission of active ions, thereby further improving the cycle performance of the battery; ), the first organic particles and the second organic particles will form a large-area glue film structure at high temperature, which can quickly reduce the diffusion channel of active ions and delay the time of thermal spread, thereby further improving the safety performance of the battery.
  • the separator includes a substrate (A) and a coating layer (B), and the coating layer (B) includes a first organic particle (B1), an inorganic particle (B2) and a first organic particle (B2).
  • Two kinds of organic particles (B3) the first kind of organic particles (B1) are secondary particles, the second kind of organic particles (B3) are primary particles, the first kind of organic particles (B1) and the second kind of organic particles (B3) Both are embedded in the inorganic particle layer formed by the inorganic particles (B2) and form protrusions on the surface of the inorganic particle layer.
  • the number-average particle size of the second organic particles is ⁇ 10 ⁇ m, and the number-average particle size of the second organic particles is ⁇ 2 ⁇ m;
  • the average particle size is 2.5 ⁇ m-6 ⁇ m.
  • the number-average particle size of the second type of organic particles is too small (for example, less than 2 ⁇ m), it is easy to swell in the electrolyte to form a film structure, and when the battery is working normally, it will block the spacer transmission channel, thereby affecting the cycle performance of the battery; If the number average particle size of the second type of organic particles is too large (for example, greater than 10 ⁇ m), it may cause excessively firm adhesion between the separator and the electrode sheet after the hot pressing process of battery preparation, resulting in poor infiltration of the electrolyte. , thereby affecting the cycle performance of the battery.
  • the mass ratio of the second organic particles in the coating is less than 10%; for example, the mass ratio of the second organic particles in the coating ranges from 2% to 10%. %, 3%-8%, 4%-9%, 5%-10%, etc.
  • the mass proportion of the second organic particles in the coating is controlled within a given range, it is helpful to make the separator coating have a suitable pore structure on the premise of ensuring the adhesion, so as to ensure the adhesion. Further improve the cycle performance and safety performance of the battery.
  • the second organic particle comprises a homopolymer or copolymer of acrylic monomeric units, a homopolymer or copolymer of acrylic monomeric units, a homopolymer or copolymer of styrenic monomeric units, or Copolymers, polyurethane-based compounds, rubber-based compounds, and one or more of the modified compounds of the above-mentioned homopolymers or copolymers.
  • the second organic particles include copolymers of acrylic monomer units and styrene monomer units, copolymers of acrylic monomer units and styrene monomer units, acrylic monomer units Monomer unit - acrylate monomer unit - copolymer of styrene monomer unit, copolymer of styrene monomer unit and unsaturated nitrile monomer unit, styrene monomer unit - olefin monomer unit - Copolymers of unsaturated nitrile monomer units, and one or more of the modified compounds of the above-mentioned copolymers.
  • the acrylic monomer unit may be selected from one or more of acrylic acid, methacrylic acid, and the like.
  • the styrene-based monomer units may be selected from one or more of styrene, methylstyrene, and the like.
  • the unsaturated nitrile monomer units may be selected from one or more of acrylonitrile, methacrylonitrile, and the like.
  • the second organic particle includes butyl acrylate-styrene copolymer, butyl methacrylate-iso-octyl methacrylate copolymer, isooctyl methacrylate-styrene copolymer, methyl methacrylate Acrylate-methacrylic acid-styrene copolymer, methyl acrylate-iso-octyl methacrylate-styrene copolymer, butyl acrylate-iso-octyl acrylate-styrene copolymer, butyl acrylate-iso-octyl methacrylate Octyl ester-styrene copolymer, butyl methacrylate-iso-octyl methacrylate-styrene copolymer, butyl methacrylate-iso-octyl acrylate-styrene copolymer,
  • the thickness of the inorganic particle layer is ⁇ 5 ⁇ m; for example, it may be 0.5 ⁇ m-4 ⁇ m, 1 ⁇ m-3 ⁇ m, 0.8 ⁇ m-3.5 ⁇ m or 1.5 ⁇ m-4.5 ⁇ m.
  • the battery can have better safety performance on the premise of higher energy density.
  • the volume average particle diameter Dv 50 of the inorganic particles is 0.5 ⁇ m-2.5 ⁇ m, optionally 0.5 ⁇ m-1 ⁇ m.
  • the volume average particle size of the inorganic particles is controlled within the given range, it helps to improve the wettability of the electrolyte in the separator, thereby further improving the cycle performance of the battery.
  • the inorganic particles include boehmite ( ⁇ -AlOOH), alumina (Al 2 O 3 ), barium sulfate (BaSO 4 ), magnesium oxide (MgO), magnesium hydroxide (Mg(OH) 2 ) , silicon dioxide (SiO 2 ), tin dioxide (SnO 2 ), titanium oxide (TiO 2 ), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ) ), one or more of nickel oxide (NiO), cerium oxide (CeO 2 ), zirconium titanate (SrTiO 3 ), barium titanate (BaTiO 3 ), and magnesium fluoride (MgF 2 ).
  • the inorganic particles are selected from one or more of boehmite ( ⁇ -AlOOH) and alumina (Al 2 O 3 ).
  • other organic compounds may also be included in the coating, for example, polymers that improve heat resistance (referred to as "heat-resistant glue” for short), dispersants, wetting agents, other types of bonding agents may be included. agent, etc.
  • heat-resistant glue polymers that improve heat resistance
  • dispersants dispersants
  • wetting agents other types of bonding agents
  • agent etc.
  • the other organic compounds mentioned above are all non-particulate substances in the coating. There is no particular limitation on the types of the above-mentioned other organic compounds in the present application, and any known materials with good improved properties can be selected.
  • the material of the substrate in the embodiments of the present application, and any known substrate with good chemical stability and mechanical stability can be selected, such as glass fiber, non-woven fabric, polyethylene, polypropylene and One or more of polyvinylidene fluoride.
  • the substrate can be a single-layer film or a multi-layer composite film.
  • the materials of each layer can be the same or different.
  • the thickness of the substrate is ⁇ 10 ⁇ m; for example, the thickness of the substrate may be 5 ⁇ m-10 ⁇ m, 5 ⁇ m-9 ⁇ m, 7 ⁇ m-9 ⁇ m.
  • the thickness of the substrate is controlled within the given range, the energy density of the battery can be further improved on the premise of ensuring the battery rate performance and safety performance.
  • the single-sided coating weight per unit area of the isolation film is ⁇ 3.0 g/m 2 ; for example, the single-sided coating weight per unit area of the isolation film may be 1.5 g/m 2 -3.0 g/ m 2 , 1.5g/m 2 -2.5g/m 2 , 1.8g/m 2 -2.3g/m 2 , etc. Controlling the coating weight on one side of the separator per unit area within the given range can further improve the energy density of the battery on the premise of ensuring the battery cycle performance and safety performance.
  • the separator satisfies one or more of the following (1)-(5):
  • the air permeability of the isolation film is 100s/100mL-300s/100mL; optionally, the air permeability of the isolation film is 150s/100mL-250s/100mL, 170s/100mL-220s/100mL;
  • the transverse tensile strength (MD) of the isolation film is 1500kgf/cm 2 -3000kgf/cm 2 ; optionally, the transverse tensile strength of the isolation film is 1800kgf/cm 2 -2500kgf/cm 2 ;
  • the longitudinal tensile strength (TD) of the separator is 1000kgf/cm 2 -2500kgf/cm 2 ; optionally, the longitudinal tensile strength of the separator is 1400kgf/cm 2 -2000kgf/cm 2 ;
  • the transverse elongation at break of the isolation film is 50%-200%; optionally, the transverse elongation at break of the isolation film is 100%-150%;
  • the longitudinal elongation at break of the separator is 50%-200%; optionally, the longitudinal elongation at break of the separator is 100%-150%.
  • the distance between any two adjacent inorganic particles is denoted as L1
  • the distance between any adjacent one inorganic particle and one organic particle is denoted as L2, then L1 ⁇ L2.
  • the particle size and number average particle size of the organic particles can be tested using equipment and methods known in the art. For example, using a scanning electron microscope (eg ZEISS Sigma 300), referring to JY/T010-1996, a scanning electron microscope (SEM) picture of the separator is obtained.
  • a scanning electron microscope eg ZEISS Sigma 300
  • multiple test samples for example, 10 can be taken to repeat the above test, and the average value of each test sample is taken as the final test result.
  • FIG. 2 is a scanning electron microscope (SEM) image of one embodiment of the separator of the present application. It can be seen from FIG. 2 that the coating layer of the isolation film includes the first organic particles and the second organic particles, and the first organic particles and the second organic particles are embedded in the inorganic particle layer and in the inorganic particle layer. Protrusions are formed on the surface of the particle layer. The particle diameter and the number average particle diameter of the organic particles can be measured from FIG. 2 according to the above method.
  • the height of the protrusions refers to the height of the protrusions formed by the first organic particles in the thickness direction of the inorganic particle layer itself, which is the distance between the “protrusions” and the “inorganic particle layer”. The maximum distance between the surfaces of the substrate”.
  • the average height of the protrusions refers to the arithmetic mean of the heights of the protrusions counted according to the number of protrusions in the isolation film coating.
  • the average height of the protrusions can be tested using equipment and methods known in the art. For example, it can be tested by ion-polished cross-sectional topography (CP) pictures. As an example, the following steps can be followed: First, cut the isolation film into a sample to be tested of a certain size (for example, 6mm ⁇ 6mm), clamp the sample to be tested with two sheets of conductive and thermally conductive sheets (such as copper foil), and place the sample to be tested.
  • CP cross-sectional topography
  • Use glue such as double-sided tape
  • a certain mass such as about 400g
  • a certain time such as 1h
  • the sample stage into the sample holder, lock it and fix it, turn on the power of the argon ion cross-section polisher (such as IB-19500CP) and evacuate (such as 10Pa-4Pa), set the argon flow (such as 0.15MPa) and voltage (such as 8KV) ) and polishing time (for example, 2 hours), adjust the sample stage to rocking mode to start polishing, and use a scanning electron microscope (for example, ZEISS Sigma300) to finally obtain the ion-polished cross-sectional topography (CP) picture of the sample to be tested.
  • the argon ion cross-section polisher such as IB-19500CP
  • evacuate such as 10Pa-4Pa
  • the argon flow such as 0.15MPa
  • voltage such as 8KV
  • polishing time for example, 2 hours
  • polishing time for example, 2 hours
  • a scanning electron microscope for example, ZEISS Sigma300
  • the arithmetic mean value of ie the ratio of the sum of the heights of each protrusion to the number of protrusions is taken as the test result of the average height of the protrusions of the final organic particles.
  • the thickness of the inorganic particle layer may also be tested by the above-mentioned ion-polished cross-sectional topography (CP) pictures.
  • CP cross-sectional topography
  • multiple test samples for example, 10 can be taken to repeat the above test, and the average value of the thickness of the inorganic particle layer in each test sample is taken as the final test result.
  • the morphology of organic particles (eg, primary particle morphology or secondary particle morphology) can also be tested by the above-mentioned ion-polished cross-sectional topography (CP) pictures.
  • CP cross-sectional topography
  • CP pictures of the isolation films of the embodiments of the present application are ion-polished cross-sectional topography (CP) pictures of the isolation films of the embodiments of the present application.
  • the coating of the isolation film includes the first organic particles, the first organic particles are secondary particles composed of multiple primary particles, and are irregular non-solid spherical cross-sections. From Fig. 3-1, the thickness (a) of the inorganic particle layer and the height (b) of the protrusions can be measured simultaneously.
  • the coating of the separator includes both the first organic particles and the second organic particles, and the second organic particles are non-agglomerated primary particles and have a solid spherical cross-section.
  • the species species of the organic particles can be tested using equipment and methods known in the art.
  • the infrared spectrum of a material can be tested to determine the characteristic peaks it contains, thereby identifying species.
  • the organic particles can be analyzed by infrared spectroscopy with instruments and methods known in the art, for example, an infrared spectrometer, such as an IS10 Fourier transform infrared spectrometer from Nicolet, USA, according to GB/T6040-2002 Infrared spectroscopy analysis method general test.
  • the volume-average particle diameter Dv 50 of the inorganic particles is a meaning known in the art, and can be measured by instruments and methods known in the art. For example, it can refer to GB/T 19077-2016 particle size distribution laser diffraction method, and use a laser particle size analyzer (for example, Master Size 3000) to measure.
  • a laser particle size analyzer for example, Master Size 3000
  • the air permeability, transverse tensile strength (MD), longitudinal tensile strength (TD), transverse elongation at break, and longitudinal elongation at break of the separator all have meanings known in the art, and can be used in the art. measured by known methods. For example, it can be tested with reference to the standard GB/T 36363-2018.
  • the distance between any two adjacent inorganic particles refers to: in the SEM image of the isolation film, any two adjacent inorganic particles in the coating (when the inorganic particles are irregular in shape) , the particle can be circumscribed), and the distance between the centers of the two inorganic particles is measured as the distance between the two inorganic particles, and recorded as L1.
  • the distance between any adjacent one inorganic particle and one organic particle refers to: in the SEM image of the isolation film, any adjacent one inorganic particle and one organic particle in the coating (when the inorganic particle is When the particle or organic particle is of irregular shape, the particle can be circumscribed), and the distance between the center of the circle of the inorganic particle and the organic particle is measured as the distance between the organic particle and the inorganic particle, denoted as L2.
  • the above-mentioned organic particles can be either the first type of organic particles or the second type of organic particles.
  • the above spacing can be measured using instruments known in the art. For example, scanning electron microscopy can be used.
  • the test can refer to JY/T010-1996. Randomly select an area in the test sample for scanning test, and acquire an SEM image of the isolation film at a certain magnification (for example, 3000 times).
  • the particle When the organic particle is an irregular body, the particle can be circumscribed), and the distance between the center of the inorganic particle (or its circumcircle) and the center of the organic particle (or its circumcircle) is measured.
  • the distance between the adjacent organic particles and inorganic particles is denoted as L2.
  • multiple groups of adjacent particles for example, 10 groups
  • the distance L1 between any two adjacent inorganic particles can also be tested according to the above method.
  • a second aspect of the present application provides a method for preparing an isolation film, the method comprising at least the following steps:
  • the coating slurry includes a component material and a solvent, the component material includes organic particles and inorganic particles, and the organic particles include the first organic particles;
  • step (3) coating the coating slurry described in step (2) on at least one side of the substrate described in step (1), forming a coating and drying to obtain the isolation film;
  • the isolation film includes: a substrate and a coating provided on at least one surface of the substrate; the coating includes organic particles and inorganic particles, and the organic particles include the first organic particles; the The inorganic particles form an inorganic particle layer, and the first organic particles are embedded in the inorganic particle layer and form protrusions on the surface of the inorganic particle layer; the number average particle size of the first organic particles is ⁇ 12 ⁇ m; The ratio of the average height of the protrusions to the thickness of the inorganic particle layer is ⁇ 4.
  • the coating may be provided on only one surface of the substrate, or may be provided on both surfaces of the substrate.
  • the release film includes a substrate (A) and a coating layer (B) provided on only one surface of the substrate (A).
  • the release film includes a substrate (A) and a coating layer (B), and the coating layer (B) is simultaneously provided on both surfaces of the substrate (A).
  • the material of the substrate in the examples of the present application, and any known substrate with good chemical stability and mechanical stability can be selected, such as glass fiber, non-woven fabric, polyethylene, polypropylene and polyethylene.
  • any known substrate with good chemical stability and mechanical stability can be selected, such as glass fiber, non-woven fabric, polyethylene, polypropylene and polyethylene.
  • the substrate can be a single-layer film or a multi-layer composite film. When the base material is a multi-layer composite film, the materials of each layer can be the same or different.
  • the solvent in step (2), may be water, such as deionized water.
  • the component material may further include the aforementioned second organic particles.
  • the second type of organic particles reference may be made to the foregoing content, which will not be repeated here.
  • the component material may also include other organic compounds, for example, may also include polymers that improve heat resistance, dispersants, wetting agents, and emulsion-like binders agent. Among them, other organic compounds are all non-particulate in the dried coating.
  • step (2) the component materials are added to the solvent and stirred uniformly to obtain a coating slurry.
  • the added mass of the first organic particles accounts for more than 12% of the total dry weight of the component materials; for example, 12%-30%, 15%-30% , 15%-25%, 15%-20%, 16%-22%.
  • the added mass of the second organic particles accounts for less than 10% of the total dry weight of the component materials, such as 2%-10%, 3%-7% , 3%-5%.
  • the dry weight of the component material is the added mass of the component material.
  • the dry weight of the component material is the product of the added mass of the component material and the solids content on a weight basis of the component material.
  • the sum of the dry weights of the component materials is the sum of the dry weights of the respective component materials.
  • the solid content of the coating slurry may be controlled at 28%-45% by weight, for example, may be 30%-38%.
  • the film surface problem of the coating and the probability of uneven coating can be effectively reduced, thereby further improving the cycle performance and safety performance of the battery.
  • step (3) the coating is performed using a coater.
  • the coating in step (3), may adopt a process such as transfer coating, spin spraying, dip coating, etc.; for example, the coating adopts transfer coating.
  • the coater includes a gravure roll; the gravure roll is used to transfer the coating slurry to the substrate.
  • the line count of the gravure roll may be 100LPI-300LPI, eg, 125LPI-190LPI (LPI is lines/inch).
  • LPI is lines/inch.
  • the coating speed in step (3), can be controlled at 30m/min-90m/min, such as 50m/min-70m/min.
  • the coating speed is within the above range, it is helpful to adjust the average height of the protrusions so that the ratio of the thickness to the thickness of the inorganic particle layer is controlled within the given range; at the same time, it can also effectively reduce the coating thickness.
  • the problem of film surface is reduced, and the probability of uneven coating is reduced, thereby further improving the cycle performance and safety performance of the battery.
  • the line speed ratio of the coating in step (3), can be controlled at 0.8-2.5, for example, can be 0.8-1.5, 1.0-1.5.
  • the drying temperature may be 40°C-70°C, for example, 50°C-60°C.
  • the drying time may be 10s-120s, for example, may be 20s-80s, 20s-40s.
  • Controlling the above process parameters within the given ranges can further improve the performance of the isolation film of the present application.
  • Those skilled in the art can selectively adjust one or more of the above-mentioned process parameters according to the actual production situation.
  • the inorganic particles and the organic particles may also optionally satisfy one or more of the aforementioned parameter conditions. It will not be repeated here.
  • the above-mentioned substrates, the first organic particles and the second organic particles are all commercially available.
  • the coating is obtained by one-time coating, which greatly simplifies the production process of the separator; at the same time, the use of the separator prepared by the above method in the battery can effectively improve the cycle performance and safety of the battery performance.
  • the positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector can be a conventional metal foil or a composite current collector (a metal material can be arranged on a polymer substrate to form a composite current collector).
  • the positive electrode current collector may use aluminum foil.
  • the specific type of the positive electrode active material is not limited, and active materials known in the art that can be used for the positive electrode of a secondary battery can be used, and those skilled in the art can select them according to actual needs.
  • the positive active material may include, but is not limited to, one or more of lithium transition metal oxides, olivine-structured lithium-containing phosphates and their respective modified compounds.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide One or more of lithium nickel cobalt aluminum oxide and its modified compounds.
  • olivine-structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, composites of lithium iron phosphate and carbon, lithium manganese phosphate, composites of lithium manganese phosphate and carbon, lithium iron manganese phosphate, lithium iron manganese phosphate One or more of the composite materials with carbon and their modified compounds. These materials are all commercially available.
  • the modification compound of each of the above materials may be doping modification and/or surface coating modification of the material.
  • the positive electrode film layer usually optionally includes a binder, a conductive agent and other optional auxiliary agents.
  • the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P(SP), graphene and carbon nanofibers.
  • the binder may be styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer One or more of (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • PAA polyacrylic acid
  • CMC carboxymethyl cellulose
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • the negative electrode sheet generally includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector can be a conventional metal foil or a composite current collector (for example, a metal material can be arranged on a polymer substrate to form a composite current collector).
  • the negative electrode current collector may use copper foil.
  • the negative electrode active materials are not limited, and active materials known in the art that can be used for secondary battery negative electrodes can be used, and those skilled in the art can select them according to actual needs.
  • the negative electrode active material may include, but is not limited to, one or more of artificial graphite, natural graphite, hard carbon, soft carbon, silicon-based materials and tin-based materials.
  • the silicon-based material may be selected from one or more of elemental silicon, silicon-oxygen compounds (eg, silicon oxide), silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material can be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. These materials are all commercially available.
  • the anode active material may include a silicon-based material.
  • the negative electrode film layer usually optionally includes a binder, a conductive agent and other optional auxiliary agents.
  • the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the binder may be styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer One or more of (EVA), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • EVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • other optional adjuvants may be thickening and dispersing agents (eg, sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials, and the like.
  • the electrolytic solution may include an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonimide (LiFSI), Lithium Trifluoromethanesulfonimide (LiTFSI), Lithium Trifluoromethanesulfonate (LiTFS), Lithium Difluorooxalate Borate (LiDFOB), Lithium Dioxalate Borate (LiBOB), Lithium Difluorophosphate (LiPO2F2), Difluorodifluorodicarbonate One or more of lithium oxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • LiPF6 lithium hexafluorophosphate
  • the solvent may be selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropylene carbonate Esters (DPC), Methyl Propyl Carbonate (MPC), Ethyl Propyl Carbonate (EPC), Butylene Carbonate (BC), Fluoroethylene Carbonate (FEC), Methyl Formate (MF), Methyl Acetate (MA) ), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), butyric acid
  • ethyl ester EB
  • PC propylene carbonate
  • EMC diethyl carbonate
  • DMC dimethyl carbonate
  • DPC dipropylene carbonate Esters
  • MPC Methyl Propyl Carbonate
  • additives are also included in the electrolyte.
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performance of the battery, such as additives to improve battery overcharge performance, additives to improve battery high temperature performance, and additives to improve battery low temperature performance. additives, etc.
  • the secondary battery of the present application is a lithium-ion secondary battery.
  • FIG. 5 is a secondary battery 5 of a square structure as an example.
  • the secondary battery may include an outer package.
  • the outer package is used to encapsulate the positive pole piece, the negative pole piece and the electrolyte.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are enclosed to form a accommodating cavity.
  • the housing 51 has an opening that communicates with the accommodating cavity, and a cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the receiving cavity.
  • the electrolyte solution is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 may be one or several, and may be adjusted according to requirements.
  • the outer packaging of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, and the like.
  • the outer package of the secondary battery may also be a soft package, such as a pouch-type soft package.
  • the material of the soft bag may be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.
  • the secondary batteries can be assembled into a battery module (Module), and the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • Module a battery module
  • the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 7 shows the battery module 4 as an example.
  • the plurality of secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed with fasteners.
  • the battery module 4 may further include a case having an accommodating space in which the plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack (Pack), and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • Pack battery pack
  • the battery pack 1 may include a battery case and a plurality of battery modules 4 disposed in the battery case.
  • the battery box includes an upper box body 2 and a lower box body 3 .
  • the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • the plurality of battery modules 4 may be arranged in the battery case in any manner.
  • the present application also provides a device comprising at least one of the secondary battery, the battery module, or the battery pack.
  • the secondary battery, battery module, or battery pack can be used as a power source for the device, or as an energy storage unit for the device.
  • the device may be, but is not limited to, mobile devices (eg, cell phones, laptops, etc.), electric vehicles (eg, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf balls) vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the device may select a secondary battery, a battery module or a battery pack according to its usage requirements.
  • Figure 10 is an apparatus as an example.
  • the device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • a battery pack or a battery module may be employed.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be thin and light, and a secondary battery can be used as a power source.
  • the base material can be purchased from Shanghai Enjie New Material Co., Ltd.
  • Inorganic particles can be purchased from One Stone Material Technology Co., Ltd.
  • the first organic particles can be purchased from Arkema (Changshu) Chemical Co., Ltd.
  • the second type of organic particles can be purchased from Sichuan Indile Technology Co., Ltd.
  • Heat-resistant glue can be purchased from Sichuan Indile Technology Co., Ltd.
  • Wetting agents are available from The Dow Chemical Company.
  • the dispersant was purchased from Changshu Weiyi Technology Co., Ltd.
  • PE polyethylene
  • step (3) Coat the coating slurry prepared in step (2) on two surfaces of a polyethylene (PE) substrate by using a coating machine, and obtain a separator 1 through processes such as drying and slitting.
  • the number of lines of the gravure roll of the coating machine is 190LPI
  • the coating speed is 70m/min
  • the coating line speed ratio is 1.3
  • the single-sided coating weight on the separator per unit area is 2.0g/m .
  • the first organic particles are embedded in the inorganic particle layer and form protrusions on the surface of the inorganic particle layer
  • the thickness of the inorganic particle layer is 2 ⁇ m
  • the average height of the protrusions The ratio to the thickness of the inorganic particle layer was 5.
  • the isolation films 2-20 are similar to the isolation film 1 in the preparation method, except that the number-average particle size, mass ratio, substance type or particle morphology of the first organic particles are adjusted, as shown in Table 1.
  • the isolation films 21-34 are similar to the isolation film 1 in the preparation method, except that the second organic particle styrene-vinyl acetate-pyrrolidone copolymer (number average molecular weight is 80,000) is also added to the coating, and To adjust the number average particle size, mass ratio, and substance type, see Table 2 for details.
  • the second organic particle styrene-vinyl acetate-pyrrolidone copolymer number average molecular weight is 80,000
  • the positive active material LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), the conductive agent carbon black (Super P), and the binder polyvinylidene fluoride (PVDF) were prepared in a mass ratio of 96.2:2.7:1.1 in an appropriate amount of solvent N- Methylpyrrolidone (NMP) is mixed evenly to obtain a positive electrode slurry, the positive electrode slurry is coated on the positive electrode current collector aluminum foil, and the positive electrode sheet is obtained by drying, cold pressing, slitting, cutting and other processes.
  • NMP N- Methylpyrrolidone
  • the negative active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) were mixed in an appropriate amount in a mass ratio of 96.4:0.7:1.8:1.1.
  • the solvent is evenly mixed with deionized water to obtain a negative electrode slurry, which is coated on the copper foil of the negative electrode current collector, and is obtained by drying, cold pressing, slitting, cutting and other processes to obtain a negative electrode pole piece.
  • Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:70 to obtain an organic solvent, and the fully dried electrolyte salt LiPF 6 is dissolved in the above mixed solvent, and the concentration of the electrolyte salt is 1.0 mol/L, and the electrolyte is obtained after mixing evenly.
  • the isolation film As the isolation film, the isolation film 1 produced by the method described above was used.
  • the secondary batteries of Examples 2-32 and Comparative Examples 1-2 were prepared similarly to the secondary batteries of Example 1, except that different separators were used, as shown in Table 1 and Table 2 for details.
  • the secondary batteries prepared in the examples and comparative examples were charged at a constant current rate of 1C to a charge cut-off voltage of 4.2V, and then charged at a constant voltage to a current of ⁇ 0.05C, left standing for 30 minutes, and then charged at a constant rate of 0.33C.
  • the cycle capacity retention rate of the battery at 45°C C1/C0 ⁇ 100%.
  • the secondary batteries prepared in the examples and comparative examples were charged at a constant current rate of 1C to a charge cut-off voltage of 4.2V, and then charged at a constant voltage to a current of ⁇ 0.05C, and allowed to stand for 10 minutes;
  • a metal heating plate is used to fasten the battery with a clamp at the position where the battery does not contact the heating plate, and a 3mm thermal insulation pad is added between the clamp and the battery, and heated at a constant temperature of 200°C until the battery thermal runaway occurs; record the time when the battery thermal runaway occurs.
  • the secondary batteries prepared in the examples and comparative examples were charged at a constant current rate of 0.5C to a charge cut-off voltage of 4.25V, and then charged at a constant voltage to a current ⁇ 0.05C, left for 30min, and then charged at 0.33C Rate constant current discharge to discharge cut-off voltage of 2.8V, stand for 30min, record the battery capacity C0 at this time.
  • the battery is tested for cyclic charge and discharge.
  • the battery capacity is attenuated by 1% on the basis of C0
  • the battery is tested by X-ray CT (X-ray computed tomography).
  • X-ray CT X-ray computed tomography
  • the inventors also conducted experiments with inorganic particles, other amounts and materials of the first organic particles and the second organic particles, other substrates, other coating process parameters and other process conditions within the scope of the present application, and obtained the results.
  • the effect of improving the cycle performance and safety performance of the battery was similar to that of Examples 1-32.

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  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
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Abstract

本申请涉及一种隔离膜，包括基材；和设置在所述基材至少一个表面上的涂层；所述涂层包括有机颗粒和无机颗粒，所述有机颗粒包括第一种有机颗粒，所述无机颗粒形成无机颗粒层，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起；所述第一种有机颗粒的数均粒径≥12μm；所述凸起的平均高度与所述无机颗粒层的厚度的比≥4。本申请还涉及该隔离膜的制备方法、含有它的二次电池及其相关的电池模块、电池包和装置。

Description

一种隔离膜、含有它的二次电池及其相关的电池模块、电池包和装置 技术领域
本申请涉及二次电池领域，具体地，涉及一种隔离膜、含有它的二次电池及其相关的电池模块、电池包和装置。
背景技术
近年来，二次电池因其重量轻、无记忆效应等优点而获得了快速的发展，被广泛应用于各种消费类电子产品和电动车辆中。随着电池行业的快速发展，人们对二次电池的性能要求越来越高。尽管技术人员为此进行了大量的研究，但二次电池的安全性能和电化学性能仍然是电池领域中的关键挑战。
有鉴于此，确有必要提供一种二次电池，其具有较好的安全性能和电化学性能，可更好地满足市场需求。
发明内容
鉴于背景技术中存在的问题，本申请提供一种隔离膜，旨在使含有其的二次电池可以同时兼顾较好的循环性能和安全性能。
为实现上述目的，本申请的第一方面提供一种隔离膜，其包括：基材和设置在所述基材至少一个表面上的涂层。所述涂层包括有机颗粒和无机颗粒。所述有机颗粒包括第一种有机颗粒，所述无机颗粒形成无机颗粒层，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起。所述第一种有机颗粒的数均粒径≥12μm。所述凸起的平均高度与所述无机颗粒层的厚度的比≥4。
相比于现有技术，本申请至少具有以下有益效果：
本申请的隔离膜在同一涂层中包含无机颗粒和第一种有机颗粒，与具有无机颗粒层和有机颗粒层两个涂层的隔离膜相比，大大减小了隔离膜的整体厚度，从而提高了电池的能量密度；且有机颗粒和无机颗粒形成特殊的涂层结构，可以保证隔离膜与电极极片之间具有良好的粘结性和接触界面，从而改善电池的循环性能；同时，在高温下工作时，隔离膜涂层结构可形成胶膜结构，有效减少离子传输通道，延缓热蔓延，从而进一步改善电池的安全性能。
在本申请任意实施方式中，所述凸起的平均高度与所述无机颗粒层的厚度的比为4-20， 可选为5-15。当凸起的平均高度与无机颗粒层的厚度的比在上述范围内时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述凸起的平均高度≥10μm，可选为12μm-18μm。当凸起的平均高度在上述范围内时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述第一种有机颗粒的数均粒径为15μm-25μm。当第一种有机颗粒的数均粒径在上述范围内时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述第一种有机颗粒为二次颗粒。当第一种有机颗粒为二次颗粒时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述第一种有机颗粒包括含氟烯基单体单元的均聚物或共聚物，烯烃基单体单元的均聚物或共聚物，不饱和腈类单体单元的均聚物或共聚物，环氧烷类单体单元的均聚物或共聚物，以及上述各均聚物或共聚物的改性化合物中的一种或几种。
在一些实施方式中，所述第一种有机颗粒包括聚四氟乙烯、聚三氟氯乙烯、聚氟乙烯、聚偏二氟乙烯、聚乙烯、聚丙烯、聚丙烯腈、聚环氧乙烷、不同含氟烯基单体单元的共聚物、含氟烯基单体单元与烯烃基单体单元的共聚物、含氟烯基单体单元与丙烯酸类单体单元的共聚物、含氟烯基单体单元与丙烯酸酯类单体单元的共聚物，以及上述各均聚物或共聚物的改性化合物中的一种或几种。
在本申请任意实施方式中，所述第一种有机颗粒包括偏二氟乙烯-三氟乙烯共聚物、偏二氟乙烯-六氟丙烯共聚物、偏二氟乙烯-三氟乙烯-六氟丙烯共聚物、偏二氟乙烯-六氟丙烯-丙烯酸共聚物、偏二氟乙烯-六氟丙烯-丙烯酸酯共聚物，以及上述共聚物的改性化合物中的一种或几种。
在本申请任意实施方式中，所述隔离膜满足下述(1)-(2)中的至少一项：
(1)所述第一种有机颗粒在所述涂层中的质量占比≥12％，可选为15％-25％；
(2)所述无机颗粒在所述涂层中的质量占比≤85％，可选为60％-75％。
当第一种有机颗粒或无机颗粒在涂层中的质量占比在上述范围内时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述有机颗粒还包括第二种有机颗粒，所述第二种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起，且所述第二种有机颗粒为一次颗粒。当涂层中还包括上述第二种有机颗粒时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述第二种有机颗粒的数均粒径≤10μm，且所述第二种有机颗粒的数均粒径≥2μm；可选地，所述第二种有机颗粒的数均粒径为2.5μm-6μm。当第二种有机颗粒的数均粒径在上述范围内时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述第二种有机颗粒在所述涂层中的质量占比为10％以下，可选为2％-10％。
在本申请任意实施方式中，所述第二种有机颗粒包括丙烯酸酯类单体单元的均聚物或共聚物，丙烯酸类单体单元的均聚物或共聚物，苯乙烯类单体单元的均聚物或共聚物，聚氨酯类化合物，橡胶类化合物，以及上述各均聚物或共聚物的改性化合物中的一种或几种；
在本申请任意实施方式中，所述第二种有机颗粒包括丙烯酸酯类单体单元与苯乙烯类单体单元的共聚物，丙烯酸类单体单元与苯乙烯类单体单元的共聚物，丙烯酸类单体单元-丙烯酸酯类单体单元-苯乙烯类单体单元的共聚物，苯乙烯类单体单元与不饱和腈类单体单元的共聚物，苯乙烯类单体单元-烯烃基单体单元-不饱和腈类单体单元的共聚物，以及上述共聚物的改性化合物中的一种或几种。
在本申请任意实施方式中，所述第二种有机颗粒包括丙烯酸丁酯-苯乙烯共聚物、甲基丙烯酸丁酯-甲基丙烯酸异辛酯共聚物、甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸酯-甲基丙烯酸-苯乙烯共聚物、丙烯酸甲酯-甲基丙烯酸异辛酯-苯乙烯共聚物、丙烯酸丁酯-丙烯酸异辛酯-苯乙烯共聚物、丙烯酸丁酯-甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸丁酯-甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸丁酯-丙烯酸异辛酯-苯乙烯共聚物、苯乙烯-丙烯腈共聚物、苯乙烯-丁二烯-丙烯腈共聚物、丙烯酸甲酯-苯乙烯-丙烯腈共聚物、甲基丙烯酸异辛酯-苯乙烯-丙烯腈共聚物、苯乙烯-醋酸乙烯酯共聚物、苯乙烯-醋酸乙烯酯-吡咯烷酮共聚物，以及上述共聚物的改性化合物中的一种或几种。
在本申请任意实施方式中，所述无机颗粒层的厚度≤5μm，可选为1μm-3μm。当无机颗粒层的厚度在上述范围内时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述无机颗粒的体积平均粒径Dv 50为0.5μm-2.5μm，可选为0.5μm-1μm。当无机颗粒层的体积平均粒径Dv 50在上述范围内时，能够进一步改善电池的循环性能和安全性能。
在本申请任意实施方式中，所述无机颗粒包括勃姆石(γ-AlOOH)、氧化铝(Al 2O 3)、硫酸钡(BaSO 4)、氧化镁(MgO)、氢氧化镁(Mg(OH) 2)、二氧化硅(SiO 2)、二氧化锡(SnO 2)、氧化钛(TiO 2)、氧化钙(CaO)、氧化锌(ZnO)、氧化锆(ZrO 2)、氧化钇(Y 2O 3)、氧化镍(NiO)、氧化铈(CeO 2)、钛酸锆(SrTiO 3)、钛酸钡(BaTiO 3)、氟化镁(MgF 2) 中的一种或几种。
在本申请任意实施方式中，所述隔离膜满足下述(1)-(5)中的一个或几个：
(1)所述隔离膜的透气度为100s/100mL-300s/100mL；可选地，所述隔离膜的透气度为150s/100mL-250s/100mL；
(2)所述隔离膜的横向拉伸强度(MD)为1500kgf/cm 2-3000kgf/cm 2；可选地，所述隔离膜的横向拉伸强度为1800kgf/cm 2-2500kgf/cm 2；
(3)所述隔离膜的纵向拉伸强度(TD)为1000kgf/cm 2-2500kgf/cm 2；可选地，所述隔离膜的纵向拉伸强度为1400kg/cm 2-2000kg/cm 2；
(4)所述隔离膜的横向断裂伸长率为50％-200％；可选地，所述隔离膜的横向断裂伸长率为100％-150％；
(5)所述隔离膜的纵向断裂伸长率为50％-200％；可选地，所述隔离膜的纵向断裂伸长率为100％-150％。
在本申请任意实施方式中，所述无机颗粒和所述有机颗粒在涂层中形成不均匀的孔道结构。
在本申请任意实施方式中，任意相邻的两个无机颗粒之间的间距记为L1，任意相邻的一个无机颗粒和一个有机颗粒之间的间距记为L2，则L1＜L2。
本申请的第二方面提供一种制备上述第一方面的隔离膜的方法，至少包括以下步骤：
(1)提供基材；
(2)提供涂层浆料，所述涂层浆料包括组分材料和溶剂，所述组分材料包括有机颗粒和无机颗粒，所述有机颗粒包括第一种有机颗粒；
(3)将步骤(2)所述的涂层浆料涂布在步骤(1)所述的基材的至少一侧，形成涂层并干燥，得到所述隔离膜；
其中，所述隔离膜包括：基材和设置在所述基材至少一个表面上的涂层；所述涂层包括有机颗粒和和无机颗粒，所述有机颗粒包括第一种有机颗粒；所述无机颗粒形成无机颗粒层，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起；所述第一种有机颗粒的数均粒径≥12μm，所述凸起的平均高度与所述无机颗粒层的厚度的比≥4。
在本申请任意实施方式中，在所述步骤(2)中，所述有机颗粒还包括第二种有机颗粒，所述第二种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起，且所述第二种有机颗粒为一次颗粒。
在本申请任意实施方式中，所述第二种有机颗粒的数均粒径≤10μm，且所述第二种有机颗粒的数均粒径≥2μm；可选地，所述第二种有机颗粒的数均粒径为2.5μm-6μm。
在本申请任意实施方式中，所述第二种有机颗粒的加入质量占所述组分材料的干重总和的10％以下，可选为2％-10％。
根据本申请第二方面所述制备隔离膜的方法，所述方法满足下述(1)-(7)中的一个或几个：
(1)在所述步骤(2)中，所述第一种有机颗粒的加入质量占所述组分材料的干重总和的12％以上；可选为12％-30％；
(2)在所述步骤(2)中，所述涂层浆料的固含量为28％-45％，可选为30％-38％，基于重量计；
(3)在所述步骤(3)中，所述涂布采用涂布机进行，所述涂布机包括凹版辊，所述凹版辊的线数为100LPI-300LPI，可选为125LPI-190LPI；
(4)在所述步骤(3)中，所述涂布的速度为30m/min-90m/min，可选为50m/min-70m/min；
(5)在所述步骤(3)中，所述涂布的线速比为0.8-2.5，可选为0.8-1.5；
(6)在所述步骤(3)中，所述干燥的温度为40℃-70℃，可选为50℃-60℃；
(7)在所述步骤(3)中，所述干燥的时间为10s-120s，可选为20s-80s。
本申请的第三方面提供一种二次电池，其包括本申请第一方面的隔离膜或根据本申请第二方面的方法制备得到的隔离膜。
本申请的第四方面提供一种电池模块，其包括本申请第三方面的二次电池。
本申请的第五方面提供一种电池包，其包括本申请第四方面的电池模块。
本申请的第六方面提供一种装置，其包括本申请第三方面的二次电池、本申请第四方面的电池模块、或本申请第五方面的电池包中的至少一种。
本申请的二次电池、电池模块、电池包和装置包括本申请提供的隔离膜，因而至少具有与本申请隔离膜相同的优势。
附图说明
为了更清楚地说明本申请的技术方案，下面将对本申请中所使用的附图作简单介绍。显而易见地，下面所描述的附图仅仅是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他附图。
图1-1是本申请隔离膜的一实施方式的结构示意图。
图1-2是本申请隔离膜的另一实施方式的结构示意图。
图2是本申请隔离膜的一实施方式的扫描电子显微镜(SEM)图片。
图3-1为本申请隔离膜的一实施方式的离子抛光断面形貌(CP)图片。
图3-2为本申请隔离膜的另一实施方式的离子抛光断面形貌(CP)图片。
图4-1是本申请隔离膜的一实施方式的结构示意图。
图4-2是本申请隔离膜的另一实施方式的结构示意图。
图5是二次电池的一实施方式的示意图。
图6是图5的分解图。
图7是电池模块的一实施方式的示意图。
图8是电池包的一实施方式的示意图。
图9是图8的分解图。
图10是二次电池用作电源的装置的一实施方式的示意图。
具体实施方式
下面结合具体实施方式，进一步阐述本申请。应理解，这些具体实施方式仅用于说明本申请而不用于限制本申请的范围。
为了简明，本文仅具体地公开了一些数值范围。然而，任意下限可以与任意上限组合形成未明确记载的范围；以及任意下限可以与其他下限组合形成未明确记载的范围，同样任意上限可以与任意其他上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其他点或单个数值组合或与其他下限或上限组合形成未明确记载的范围。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”包括本数，“一种或几种”中“几种”的含义是两种及两种以上。
在本文的描述中，除非另有说明，术语“或(or)”是包括性的。也就是说，短语“A或(or)B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量 (例如，可以按照在本申请的实施例中给出的方法进行测试)。
二次电池
二次电池，是指在电池放电后可通过充电的方式使活性材料激活而继续使用的电池。
通常情况下，二次电池包括正极极片、负极极片、隔离膜及电解液。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。隔离膜设置在正极极片和负极极片之间，起到隔离的作用。电解液在正极极片和负极极片之间起到传导离子的作用。
隔离膜
本申请提供一种隔离膜，其包括基材和设置在所述基材至少一个表面上的涂层。所述涂层包括有机颗粒和无机颗粒。所述有机颗粒包括第一种有机颗粒，所述无机颗粒形成无机颗粒层，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起。所述第一种有机颗粒的数均粒径≥12μm。所述凸起的平均高度与所述无机颗粒层的厚度的比≥4。
需要说明的是，所述有机颗粒的数均粒径是指在隔离膜涂层中，按有机颗粒数量统计的有机颗粒的粒径的算术平均值。所述有机颗粒的粒径是指有机颗粒上相隔最远的两点间的距离。
本申请的隔离膜在同一涂层中包含无机颗粒和第一种有机颗粒，与具有无机颗粒层和有机颗粒层两个涂层的隔离膜相比，大大减小了隔离膜的整体厚度，从而提高了电池的能量密度；且对第一种有机颗粒做了特殊设计，使得包含本申请隔离膜的电池具有较好的循环性能和安全性能。不希望囿于任何理论，这可能是因为，由于隔离膜无机涂层中具有充足的不均匀的孔隙，可保证离子的传输通道畅通，且第一种有机颗粒可以使隔离膜与电极极片之间具有良好的粘结性和接触界面，有效改善电池的循环性能；同时，在高温下工作时，第一种有机颗粒能够形成大量的胶膜结构，可以减少离子传输通道，延缓热蔓延，从而获得良好的安全性能。
如图1-1所示，所述隔离膜包括基材(A)和涂层(B)，所述涂层(B)中包括第一种有机颗粒(B1)和无机颗粒(B2)，第一种有机颗粒(B1)为二次颗粒，且第一种有机颗粒嵌于所述无机颗粒(B2)形成的无机颗粒层中且在所述无机颗粒层表面形成凸起。
本申请人进一步研究发现，当本申请的隔离膜在上述设计条件的基础上，还可选地满足下述条件中的一个或几个时，可以进一步改善包含本申请隔离膜的二次电池的性能。
在一些实施方式中，所述凸起的平均高度与所述无机颗粒层的厚度的比为4-20，可选为5-15。当凸起的平均高度与无机颗粒层的厚度的比在上述范围内时，可以进一步改善电池的循环性能和安全性能。发明人经大量研究发现，当二者的比值过小时，在电池制备过程的化成工序中不利于气体排出，在电池充电过程中，气体会阻碍离子传输，从而造成负极极片表面产生黑斑，从而影响电池的循环性能；当二者的比值过大时，可能导致离子传输路径增大，在电池循环过程中负极极片表面容易析锂，从而影响电池的安全性能。
在一些实施方式中，所述凸起的平均高度≥10μm，可选为12μm-18μm。在凸起的平均高度在上述范围内时，既可提供隔离膜与极片之间足够的粘结力，又可以降低在电池制备过程中隔离膜打皱的风险，有效降低正负极发生短路的概率，从而进一步改善电池的安全性能。
在一些实施方式中，所述第一种有机颗粒的粒径为8μm-35μm。当第一种有机颗粒的粒径在上述范围内时，可形成较多的孔隙结构，改善隔离膜的离子传输性能。需要说明的是，在本申请中，第一种有机颗粒的粒径≥8μm是指在所使用的所有的第一种有机颗粒中，单个第一种有机颗粒的粒径均≥8μm，例如为8μm、10μm、12μm等。
在一些实施方式中，所述第一种有机颗粒的数均粒径为15μm-25μm。当第一种有机颗粒的数均粒径在上述范围内时，第一种有机颗粒的粒径分布相对均匀，在实现本申请技术效果的前体下，有利于形成相对均匀的涂层界面。
在一些实施方式中，第一种有机颗粒为二次颗粒。当第一种有机颗粒为二次颗粒时，有助于形成均匀的涂层界面，当将隔离膜用到电池后，可以有效改善电池制备过程中的极耳错位问题，从而进一步改善电池的安全性能。
需要说明的是，一次颗粒和二次颗粒具有本领域公知的含义。一次颗粒是指没有形成团聚状态的颗粒。二次颗粒是指由两个或两个以上一次颗粒聚集而成的团聚态的颗粒。
在一些实施方式中，第一种有机颗粒可以由粒径为150nm-300nm的一次颗粒团聚而成。
在一些实施方式中，第一种有机颗粒包括含氟烯基单体单元的均聚物或共聚物，烯烃基单体单元的均聚物或共聚物，不饱和腈类单体单元的均聚物或共聚物，环氧烷类单体单元的均聚物或共聚物，以及上述各均聚物或共聚物的改性化合物中的一种或几种。
在一些实施方式中，所述第一种有机颗粒包括聚四氟乙烯、聚三氟氯乙烯、聚氟乙烯、聚偏二氟乙烯、聚乙烯、聚丙烯、聚丙烯腈、聚环氧乙烷、不同含氟烯基单体单元的共聚物、含氟烯基单体单元与烯烃基单体单元的共聚物、含氟烯基单体单元与丙烯酸类单体单元的共聚物、含氟烯基单体单元与丙烯酸酯类单体单元的共聚物，以及上述各均聚物或共 聚物的改性化合物中的一种或几种。
在一些实施方式中，第一种有机颗粒包括偏二氟乙烯-三氟乙烯共聚物、偏二氟乙烯-六氟丙烯共聚物、偏二氟乙烯-三氟乙烯-六氟丙烯共聚物、偏二氟乙烯-六氟丙烯-丙烯酸共聚物、偏二氟乙烯-六氟丙烯-丙烯酸酯共聚物，以及上述共聚物的改性化合物中的一种或几种。
在一些实施方式中，第一种有机颗粒为聚偏二氟乙烯、偏二氟乙烯-六氟丙烯共聚物，以及上述各均聚物或共聚物的改性化合物中的一种或几种。
在一些实施方式中，所述隔离膜满足下述(1)-(2)中的至少一项：
(1)所述第一种有机颗粒在所述涂层中的质量占比≥12％，可选为15％-25％。
(2)所述无机颗粒在所述涂层中的质量占比≤85％，可选为60％-75％。
通过选择适当的有机颗粒和无机颗粒的用量，可以使两者发挥更好的协同作用，确保隔离膜在保证安全性能的前提下，还具有适当的不均匀的孔道结构，同时实现隔离膜的轻质化，从而进一步改善电池的能量密度。
在一些实施方式中，所述有机颗粒还包括第二种有机颗粒，所述第二种有机颗粒嵌入所述无机颗粒中且在所述无机颗粒层表面形成凸起，且所述第二种有机颗粒为一次颗粒。当电池在正常工作环境(例如45℃以下)中时，将第一种有机颗粒和第二种有机颗粒搭配使用可以有效降低涂层中的有机颗粒在电解液中被溶胀后形成致密且面积较大的胶膜的机率，使得隔离膜涂层中具有适度的不均匀的孔道结构，便于活性离子的传输，从而进一步改善电池的循环性能；特别地，当电池处于高温工作环境(例如100℃以上)中时，第一种有机颗粒和第二种有机颗粒在高温下会形成大面积的胶膜结构，快速减少活性离子的扩散通道，延缓热蔓延的时间，从而进一步改善电池的安全性能。
如图1-2所示，所述隔离膜包括基材(A)和涂层(B)，所述涂层(B)中包括第一种有机颗粒(B1)、无机颗粒(B2)和第二种有机颗粒(B3)，第一种有机颗粒(B1)为二次颗粒，第二种有机颗粒(B3)为一次颗粒，第一种有机颗粒(B1)和第二种有机颗粒(B3)均嵌于所述无机颗粒(B2)形成的无机颗粒层中且在所述无机颗粒层表面形成凸起。
在一些实施方式中，所述第二种有机颗粒的数均粒径≤10μm，且所述第二种有机颗粒的数均粒径≥2μm；可选地，所述第二种有机颗粒的数均粒径为2.5μm-6μm。当第二种有机颗粒的数均粒径在所给范围内时，能够进一步改善电池的循环性能和安全性能。第二种有机颗粒的数均粒径如果过小(例如小于2μm)，其在电解液中容易溶胀形成胶膜结构，在电池正常工作时，会阻隔离子传输通道，从而影响电池的循环性能；第二种有机颗粒的 数均粒径如果过大(例如大于10μm)，其在电池制备的热压过程后，可能造成隔离膜与电极极片之间过牢固粘接，导致电解液的浸润不良，从而影响电池的循环性能。
在一些实施方式中，第二种有机颗粒在所述涂层中的质量占比为10％以下；例如，所述第二种有机颗粒在所述涂层中的质量占比为2％-10％，3％-8％，4％-9％，5％-10％等。当将第二种有机颗粒在所述涂层中的质量占比控制在所给范围内时，有助于使隔离膜涂层在保证粘结性的前提下，还具有合适的孔道结构，从而进一步改善电池的循环性能和安全性能。
在一些实施方式中，第二种有机颗粒包括丙烯酸酯类单体单元的均聚物或共聚物，丙烯酸类单体单元的均聚物或共聚物，苯乙烯类单体单元的均聚物或共聚物，聚氨酯类化合物，橡胶类化合物，以及上述各均聚物或共聚物的改性化合物中的一种或几种。
在一些实施方式中，所述第二种有机颗粒包括丙烯酸酯类单体单元与苯乙烯类单体单元的共聚物，丙烯酸类单体单元与苯乙烯类单体单元的共聚物，丙烯酸类单体单元-丙烯酸酯类单体单元-苯乙烯类单体单元的共聚物，苯乙烯类单体单元与不饱和腈类单体单元的共聚物，苯乙烯类单体单元-烯烃基单体单元-不饱和腈类单体单元的共聚物，以及上述共聚物的改性化合物中的一种或几种。
在一些实施方式中，所述丙烯酸类单体单元可以选自丙烯酸、甲基丙烯酸等中的一种或几种。
在一些实施方式中，所述苯乙烯类单体单元可选自苯乙烯、甲基苯乙烯等中的一种或几种。
在一些实施方式中，所述不饱和腈类单体单元可选自丙烯腈、甲基丙烯腈等中的一种或几种。
在一些实施方式中，第二种有机颗粒包括丙烯酸丁酯-苯乙烯共聚物、甲基丙烯酸丁酯-甲基丙烯酸异辛酯共聚物、甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸酯-甲基丙烯酸-苯乙烯共聚物、丙烯酸甲酯-甲基丙烯酸异辛酯-苯乙烯共聚物、丙烯酸丁酯-丙烯酸异辛酯-苯乙烯共聚物、丙烯酸丁酯-甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸丁酯-甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸丁酯-丙烯酸异辛酯-苯乙烯共聚物、苯乙烯-丙烯腈共聚物、苯乙烯-丁二烯-丙烯腈共聚物、丙烯酸甲酯-苯乙烯-丙烯腈共聚物、甲基丙烯酸异辛酯-苯乙烯-丙烯腈共聚物、苯乙烯-醋酸乙烯酯共聚物、苯乙烯-醋酸乙烯酯-吡咯烷酮共聚物，以及上述共聚物的改性化合物中的一种或几种。
在一些实施方式中，所述无机颗粒层的厚度≤5μm；例如可以为0.5μm-4μm、1μm-3μm、 0.8μm-3.5μm或1.5μm-4.5μm。当将所述无机颗粒层的厚度控制在上述范围内时，电池可以在具有较高能量密度的前提下，还具有较好的安全性能。
在一些实施方式中，无机颗粒的体积平均粒径Dv 50为0.5μm-2.5μm，可选为0.5μm-1μm。当无机颗粒的体积平均粒径控制在所给范围内时，有助于提高电解液在隔离膜中的浸润性，从而进一步改善电池的循环性能。
在一些实施方式中，无机颗粒包括勃姆石(γ-AlOOH)、氧化铝(Al 2O 3)、硫酸钡(BaSO 4)、氧化镁(MgO)、氢氧化镁(Mg(OH) 2)、二氧化硅(SiO 2)、二氧化锡(SnO 2)、氧化钛(TiO 2)、氧化钙(CaO)、氧化锌(ZnO)、氧化锆(ZrO 2)、氧化钇(Y 2O 3)、氧化镍(NiO)、氧化铈(CeO 2)、钛酸锆(SrTiO 3)、钛酸钡(BaTiO 3)、氟化镁(MgF 2)中的一种或几种。例如，可选地，无机颗粒选自勃姆石(γ-AlOOH)、氧化铝(Al 2O 3)中的一种或几种。
根据一些实施例，所述涂层中还可以包括其他有机化合物，例如，可以包括改善耐热性的聚合物(简称为“耐热胶”)、分散剂、润湿剂、其他种类的粘结剂等。上述其他有机化合物在涂层中均为非颗粒状的物质。本申请对上述其他有机化合物的种类没有特别的限制，可以选用任意公知的具有良好改善性能的材料。
本申请的实施例对所述基材的材质没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的基材，例如玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或几种。所述基材可以是单层薄膜，也可以是多层复合薄膜。当所述基材为多层复合薄膜时，各层的材料可以相同，也可以不同。
在一些实施方式中，所述基材的厚度≤10μm；例如，所述基材的厚度可以为5μm-10μm，5μm-9μm，7μm-9μm。当所述基材的厚度控制在所给范围内时，可以在确保电池倍率性能和安全性能的前提下，进一步提高电池的能量密度。
在一些实施方式中，单位面积的隔离膜上单面的涂层重量≤3.0g/m 2；例如，单位面积的隔离膜上单面的涂层重量可以为1.5g/m 2-3.0g/m 2，1.5g/m 2-2.5g/m 2，1.8g/m 2-2.3g/m 2等。将单位面积的隔离膜上单面的涂层重量控制在所给范围内，可以在确保电池循环性能和安全性能的前提下，进一步提高电池的能量密度。
在一些实施方式中，所述隔离膜满足下述(1)-(5)中的一个或几个：
(1)所述隔离膜的透气度为100s/100mL-300s/100mL；可选地，所述隔离膜的透气度为150s/100mL-250s/100mL，170s/100mL-220s/100mL；
(2)所述隔离膜的横向拉伸强度(MD)为1500kgf/cm 2-3000kgf/cm 2；可选地，所述隔离膜的横向拉伸强度为1800kgf/cm 2-2500kgf/cm 2；
(3)所述隔离膜的纵向拉伸强度(TD)为1000kgf/cm 2-2500kgf/cm 2；可选地，所述隔离膜的纵向拉伸强度为1400kgf/cm 2-2000kgf/cm 2；
(4)所述隔离膜的横向断裂伸长率为50％-200％；可选地，所述隔离膜的横向断裂伸长率为100％-150％；
(5)所述隔离膜的纵向断裂伸长率为50％-200％；可选地，所述隔离膜的纵向断裂伸长率为100％-150％。
在任意实施方式中，任意相邻的两个无机颗粒之间的间距记为L1，任意相邻的一个无机颗粒和一个有机颗粒之间的间距记为L2，则L1＜L2。
相关参数测试方法
根据一些实施例，有机颗粒的粒径和数均粒径可以采用本领域已知的设备和方法进行测试。例如，使用扫描电子显微镜(例如ZEISS Sigma 300)，参考JY/T010-1996，获取隔离膜的扫描电子显微镜(SEM)图片。作为示例，可以按照如下方法测试：在隔离膜上任意选取一个长×宽＝50mm×100mm的测试样品，在测试样品中随机选取多个测试区域(例如5个)，并在一定放大倍率(例如在测量第一种有机颗粒时为500倍，测量第二种有机颗粒时为1000倍)下，读取各测试区域中各有机颗粒的粒径(即：取有机颗粒上最远的两点间的距离作为该有机颗粒的粒径)，统计各测试区域中有机颗粒的数量和粒径数值，取各测试区域中有机颗粒粒径的算术平均值，即为该测试样品中有机颗粒的数均粒径。为了确保测试结果的准确性，可以取多个测试样品(例如10个)重复进行上述测试，取各个测试样品的平均值作为最终的测试结果。
图2是本申请隔离膜的一实施方式的扫描电子显微镜(SEM)图片。从图2可以看出，隔离膜的涂层中包括第一种有机颗粒和第二种有机颗粒，且第一种有机颗粒和第二种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起。可以根据上述方法，从图2中测量有机颗粒的粒径和数均粒径。
需要说明的是，所述凸起的高度是指所述第一种有机颗粒在无机颗粒层自身厚度方向上形成的凸起的高度，其是所述“凸起”与“无机颗粒层背向基材的表面”之间的最大距离。
所述凸起的平均高度是指在隔离膜涂层中，按照凸起数量统计的所述凸起高度的算术平均值。
根据一些实施例，所述凸起的平均高度可以采用本领域已知的设备和方法进行测试。例如，可以通过离子抛光断面形貌(CP)图片进行测试。作为示例，可按如下步骤操作： 首先将隔离膜裁成一定尺寸的待测样品(例如6mm×6mm)，用两片导电导热的薄片(如铜箔)将待测样品夹住，将待测样品与薄片之间用胶(如双面胶)粘住固定，用一定质量(如400g左右)平整铁块压一定时间(如1h)，使待测样品与铜箔间缝隙越小越好，然后用剪刀将边缘剪齐，粘在具有导电胶的样品台上，样品略突出样品台边缘即可。然后将样品台装进样品架上锁好固定，打开氩离子截面抛光仪(例如IB-19500CP)电源并抽真空(例如10Pa-4Pa)，设置氩气流量(例如0.15MPa)和电压(例如8KV)以及抛光时间(例如2小时)，调整样品台为摇摆模式开始抛光，使用扫描电子显微镜(例如ZEISS Sigma300)最终得到待测样品的离子抛光断面形貌(CP)图片。统计离子抛光断面形貌(CP)图片中有机颗粒形成凸起的个数和凸起的高度；取多个测试样品(例如10个)重复进行上述测试，取各个测试样品中所有凸起的高度的算术平均值(即各凸起高度的总和与凸起个数的比值)作为最终的有机颗粒的凸起的平均高度的测试结果。
根据一些实施例，无机颗粒层的厚度也可以通过上述离子抛光断面形貌(CP)图片进行测试。为了测试结果的准确性，可以取多个测试样品(例如10个)重复进行上述测试，取各个测试样品中无机颗粒层厚度的平均值作为最终的测试结果。
根据一些实施例，有机颗粒的形貌(例如：一次颗粒形貌或二次颗粒形貌)也可以通过上述离子抛光断面形貌(CP)图片进行测试。
图3-1和图3-2是本申请实施例的隔离膜的离子抛光断面形貌(CP)图片。
由图3-1可以看出，隔离膜的涂层中包括第一种有机颗粒，第一种有机颗粒是由多个一次颗粒组成的二次颗粒，且为不规则的非实心球体截面。从图3-1中可以同时测量无机颗粒层的厚度(a)和凸起的高度(b)。
由图3-2可以看出，隔离膜的涂层中同时包括第一种有机颗粒和第二种有机颗粒，第二种有机颗粒是非团聚体的一次颗粒，且为实心球体截面。
根据一些实施例，有机颗粒的物质种类可以采用本领域已知的设备和方法进行测试。例如，可以测试材料的红外光谱，确定其包含的特征峰，从而确定物质种类。具体地，可以用本领域公知的仪器及方法对有机颗粒进行红外光谱分析，例如红外光谱仪，如采用美国尼高力(Nicolet)公司的IS10型傅里叶变换红外光谱仪，依据GB/T6040-2002红外光谱分析方法通则测试。
根据一些实施例，无机颗粒的体积平均粒径Dv 50为本领域公知的含义，可采用本领域已知的仪器及方法进行测定。例如可以参照GB/T 19077-2016粒度分布激光衍射法，采用激光粒度分析仪(例如Master Size 3000)测定。
根据一些实施例，隔离膜的透气度、横向拉伸强度(MD)、纵向拉伸强度(TD)、横向断裂伸长率、纵向断裂伸长率均具有本领域公知的含义，可以采用本领域已知的方法进行测量。例如，均可参照标准GB/T 36363-2018进行测试。
根据一些实施例，任意相邻的两个无机颗粒之间的间距是指：在隔离膜的SEM图像中，在涂层中任取相邻的两个无机颗粒(当无机颗粒为不规则形状时，可以对该颗粒做外接圆处理)，测试两个无机颗粒的圆心间距作为两个无机颗粒之间的间距，并记为L1。
根据一些实施例，任意相邻的一个无机颗粒和一个有机颗粒之间的间距是指：在隔离膜的SEM图像中，在涂层中任取相邻的一个无机颗粒和一个有机颗粒(当无机颗粒或有机颗粒为不规则形状时，可以对该颗粒做外接圆处理)，测试该无机颗粒和该有机颗粒的圆心间距作为有机颗粒和无机颗粒之间的间距，记为L2。上述有机颗粒可以取第一种有机颗粒，也可以取第二种有机颗粒。
上述间距可采用本领域已知的仪器进行测定。例如可以采用扫描电子显微镜测定。作为示例，任意相邻的一个无机颗粒和一个有机颗粒之间的间距L2可以按如下方法测试：将隔离膜制成长×宽＝50mm×100mm的测试样品；使用扫描电子显微镜(例如ZEISS Sigma300)对隔离膜进行测试。测试可参考JY/T010-1996。在测试样品中随机选取区域进行扫描测试，并在一定放大倍率(例如3000倍)下获取隔离膜的SEM图像，在SEM图像中任选相邻的一个无机颗粒和一个有机颗粒(当无机颗粒或有机颗粒为不规则体时，可以对该颗粒做外接圆处理)，测量无机颗粒(或其外接圆)的圆心与有机颗粒(或其外接圆)的圆心之间的距离，即为本申请所述的相邻的有机颗粒和无机颗粒的间距，记为L2。为了确保测试结果的准确性，可以在测试样品中取多组相邻颗粒(例如10组)重复进行上述测试，取各组测试结果的平均值作为最终的结果。
同理，也可以按照上述方法测试任意相邻的两个无机颗粒之间的间距L1。
上述“外接圆”意指球将不规则体包围，且不规则体的顶点和弧面在此圆上。
隔离膜的制备方法
本申请的第二方面提供一种制备隔离膜的方法，该方法至少包括以下步骤：
(1)提供基材；
(2)提供涂层浆料，所述涂层浆料包括组分材料和溶剂，所述组分材料包括有机颗粒和无机颗粒，所述有机颗粒包括第一种有机颗粒；
(3)将步骤(2)所述的涂层浆料涂布在步骤(1)所述的基材的至少一侧，形成涂 层并干燥，得到所述隔离膜；
其中，所述隔离膜包括：基材和设置在所述基材至少一个表面上的涂层；所述涂层包括有机颗粒和无机颗粒，所述有机颗粒包括所述第一种有机颗粒；所述无机颗粒形成无机颗粒层，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起；所述第一种有机颗粒的数均粒径≥12μm；所述凸起的平均高度与所述无机颗粒层的厚度的比≥4。
所述涂层可以设置在所述基材的仅一个表面上，也可以设置在所述基材的两个表面上。
如图4-1所示，隔离膜包括基材(A)和涂层(B)，所述涂层(B)设置在所述基材(A)的仅一个表面上。
如图4-2所示，隔离膜包括基材(A)和涂层(B)，所述涂层(B)同时设置在所述基材(A)的两个表面上。
本申请实施例对所述基材的材质没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的基材，例如玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或几种。所述基材可以是单层薄膜，也可以是多层复合薄膜。当所述基材为多层复合薄膜时，各层的材料可以相同，也可以不同。
在一些实施方式中，在步骤(2)中，所述溶剂可以为水，例如去离子水。
在一些实施方式中，在步骤(2)中，所述组分材料还可以包括前述的第二种有机颗粒。第二种有机颗粒的各参数可参考前述内容，此处不再赘述。
在一些实施方式中，在步骤(2)中，所述组分材料还可以包括其他有机化合物，例如，还可以包括改善耐热性的聚合物、分散剂、润湿剂、乳液状的粘结剂。其中，其他有机化合物在干燥后的涂层中均为非颗粒状。
在一些实施方式中，在步骤(2)中，在溶剂中加入组分材料并搅拌均匀得到涂层浆料。
在一些实施方式中，在步骤(2)中，所述第一种有机颗粒的加入质量占所述组分材料的干重总和的12％以上；例如12％-30％，15％-30％，15％-25％，15％-20％，16％-22％。
在一些实施方式中，在步骤(2)中，所述第二种有机颗粒的加入质量占所述组分材料的干重总和的10％以下，例如2％-10％，3％-7％，3％-5％。
需要说明的是，当组分材料为固态时，组分材料的干重为该组分材料的加入质量。当组分材料为悬浮液、乳液或溶液时，组分材料的干重为该组分材料的加入质量与该组分材料基于重量计的固含量的乘积。所述组分材料的干重总和即为各组分材料的干重的加和。
在一些实施方式中，在步骤(2)中，涂层浆料基于重量计的固含量可以控制在28％-45％，例如，可以为30％-38％。当涂层浆料的固含量在上述范围内时，可以有效减少涂层的膜面问题以及降低涂布不均匀出现的概率，从而进一步改善电池的循环性能和安全性能。
在一些实施方式中，在步骤(3)中，所述涂布采用涂布机进行实施。
在本申请实施例中，对涂布机的型号没有特殊限制，可以采用市购的涂布机。
在一些实施方式中，在步骤(3)中，所述涂布可以采用转移涂布、旋转喷涂、浸涂等工艺；例如所述涂布采用转移涂布。
在一些实施方式中，所述涂布机包括凹版辊；所述凹版辊用于将涂层浆料转移到基材上。
在一些实施方式中，所述凹版辊的线数可以为100LPI-300LPI，例如，125LPI-190LPI(LPI为线/英寸)。当凹版辊的线数在上述范围内时，有助于控制第一种有机颗粒和第二种有机颗粒的数量，从而进一步改善隔离膜的循环性能和安全性能。
在一些实施方式中，在步骤(3)中，所述涂布的速度可以控制在30m/min-90m/min，例如50m/min-70m/min。当涂布的速度在上述范围内时，有助于调整所述凸起的平均高度，使其与所述无机颗粒层厚度的比控制在所给范围内；同时，还可以有效减少涂层的膜面问题，降低涂布不均匀的概率，从而进一步改善电池的循环性能和安全性能。
在一些实施方式中，在步骤(3)中，所述涂布的线速比可以控制在0.8-2.5，例如可以为0.8-1.5，1.0-1.5。
在一些实施方式中，在步骤(3)中，所述干燥的温度可以为40℃-70℃，例如可以为50℃-60℃。
在一些实施方式中，在步骤(3)中，所述干燥的时间可以为10s-120s，例如可以为20s-80s，20s-40s。
将上述各工艺参数控制在所给范围内，可以进一步改善本申请的隔离膜的使用性能。本领域的技术人员可以根据实际生产情况，选择性地调控上述一个或几个工艺参数。
为了进一步改善二次电池的性能，所述无机颗粒和所述有机颗粒还可选地满足前述的各参数条件中的一个或几个。此处不再赘述。
上述基材、第一种有机颗粒和第二种有机颗粒均可以通过市购获得。
本申请的隔离膜制备方法，通过一次涂布制得涂层，大大简化了隔离膜的生产工艺流程；同时，将上述方法制备的隔离膜用到电池中，可以有效改善电池的循环性能和安全性能。
正极极片
在二次电池中，所述正极极片通常包括正极集流体及设置在正极集流体上的正极膜层，所述正极膜层包括正极活性材料。
所述正极集流体可以采用常规金属箔片或复合集流体(可以将金属材料设置在高分子基材上形成复合集流体)。作为示例，正极集流体可以采用铝箔。
所述正极活性材料的具体种类不做限制，可以采用本领域已知的能够用于二次电池正极的活性材料，本领域技术人员可以根据实际需求进行选择。
作为示例，所述正极活性材料可以包括，但不限于，锂过渡金属氧化物，橄榄石结构的含锂磷酸盐及其各自的改性化合物中的一种或几种。锂过渡金属氧化物的示例可包括但不限于锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物及其改性化合物中的一种或几种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂、磷酸铁锂与碳的复合材料、磷酸锰锂、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料及其改性化合物中的一种或几种。这些材料均可以通过商业途径获得。
在一些实施方式中，上述各材料的改性化合物可以是对材料进行掺杂改性和/或表面包覆改性。
所述正极膜层通常还可选地包括粘结剂、导电剂和其他可选助剂。
作为示例，导电剂可以为超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、Super P(SP)、石墨烯及碳纳米纤维中一种或几种。
作为示例，粘结剂可以为丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚丙烯酸(PAA)、羧甲基纤维素(CMC)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或几种。
负极极片
在二次电池中，所述负极极片通常包括负极集流体及设置在负极集流体上的负极膜层，所述负极膜层包括负极活性材料。
所述负极集流体可以采用常规金属箔片或复合集流体(例如可以将金属材料设置在高分子基材上形成复合集流体)。作为示例，负极集流体可以采用铜箔。
所述负极活性材料的具体种类不做限制，可以采用本领域已知的能够用于二次电池负极的活性材料，本领域技术人员可以根据实际需求进行选择。作为示例，所述负极活性材料可以包括，但不限于，人造石墨、天然石墨、硬碳、软碳、硅基材料和锡基材料中的一种或几种。所述硅基材料可选自单质硅、硅氧化合物(例如氧化亚硅)、硅碳复合物、硅氮复合物、硅合金中的一种或几种。所述锡基材料可选自单质锡、锡氧化合物、锡合金中的一种或几种。这些材料均可以通过商业途径获得。
在一些实施方式中，为了进一步提高电池的能量密度，所述负极活性材料可以包括硅基材料。
所述负极膜层通常还可选地包括粘结剂、导电剂和其他可选助剂。
作为示例，导电剂可以为超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或几种。
作为示例，粘结剂可以为丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或几种。
作为示例，其他可选助剂可以是增稠及分散剂(例如羧甲基纤维素钠CMC-Na)、PTC热敏电阻材料等。
电解液
本申请实施例对电解液的选择没有特殊限制，电解液用于在正极极片和负极极片之间起传导离子的作用。电解液可以包括电解质盐和溶剂。
作为示例，电解质盐可选自六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、高氯酸锂(LiClO4)、六氟砷酸锂(LiAsF6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO2F2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸锂(LiTFOP)中的一种或几种。
作为示例，溶剂可选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜 (MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
在一些实施方式中，电解液中还包括添加剂。例如添加剂可以包括负极成膜添加剂，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
在一些实施方式中，本申请的二次电池为锂离子二次电池。
本申请实施例对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图5是作为一个示例的方形结构的二次电池5。
在一些实施方式中，二次电池可包括外包装。该外包装用于封装正极极片、负极极片和电解液。
在一些实施方式中，参照图6，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。
正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或几个，可根据需求来调节。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)等中的一种或几种。
在一些实施方式中，二次电池可以组装成电池模块(Module)，电池模块所含二次电池的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图7是作为一个示例的电池模块4。参照图7，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的壳体，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包(Pack)，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图8和图9是作为一个示例的电池包1。参照图8和图9，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任 意的方式排布于电池箱中。
装置
本申请还提供一种装置，所述装置包括所述的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块或电池包可以用作所述装置的电源，也可以作为所述装置的能量存储单元。所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
所述装置可以根据其使用需求来选择二次电池、电池模块或电池包。
图10是作为一个示例的装置。该设备为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该设备对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的设备可以是手机、平板电脑、笔记本电脑等。该设备通常要求轻薄化，可以采用二次电池作为电源。
以下结合实施例进一步说明本申请的有益效果。
实施例
为了使本申请所解决的技术问题、技术方案及有益效果更加清楚，以下将结合实施例和附图对本申请进行进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用的任何限制。基于本申请中的实施例，本领域普通技术人员在没有付出创造性劳动前提下所获得的所有其他实施例都属于本申请保护的范围。
本申请中所使用的材料均可以商购获得。
例如：基材可以购于上海恩捷新材料有限公司。
无机颗粒可以购于壹石通材料科技股份有限公司。
第一种有机颗粒可以购于阿科玛(常熟)化学有限公司。
第二种有机颗粒可以购于四川茵地乐科技有限公司。
耐热胶可以购自四川茵地乐科技有限公司。
润湿剂可以购自陶氏化学公司。
分散剂购自常熟威怡科技有限公司。
一、隔离膜的制备
隔离膜1
(1)提供聚乙烯(PE)基材，例如，基材的厚度为7μm，孔隙率为36％；
(2)配制涂层浆料：将无机颗粒氧化铝(Al 2O 3)、第一种有机颗粒偏二氟乙烯-六氟丙烯共聚物(数均分子量为55万)、耐热胶丙烯酸-丙烯腈共聚物：分散剂羧甲基纤维素钠(CMC-Na)和润湿剂有机硅改性聚醚以73：20：5：1.5：0.5的干重比在适量的去离子水中混合均匀，得到基于重量计固含量为35％的涂层浆料。其中，第一种有机颗粒的数均粒径为12μm，无机颗粒氧化铝(Al 2O 3)的体积平均粒径Dv 50为1μm。
(3)将步骤(2)配制的涂层浆料采用涂布机涂布在聚乙烯(PE)基材的2个表面上，通过干燥、分切等工序，得到隔离膜1。其中，涂布机的凹版辊的线数为190LPI，涂布的速度为70m/min，涂布的线速比为1.3；单位面积的隔离膜上的单面涂层重量为2.0g/m 2。在所述隔离膜中，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起，所述无机颗粒层的厚度为2μm，所述凸起的平均高度与所述无机颗粒层的厚度的比为5。
隔离膜2-20与隔离膜1的制备方法相似，不同点在于：调整了第一种有机颗粒的数均粒径、质量占比、物质种类或颗粒形貌，详见表1。
隔离膜21-34与隔离膜1的制备方法相似，不同点在于：在涂层中还加入了第二种有机颗粒苯乙烯-醋酸乙烯酯-吡咯烷酮共聚物(数均分子量为8万)，并调整其数均粒径、质量占比、物质种类，详见表2。
所制备隔离膜的性质汇总于表1和表2中。
二、电池的制备
1、正极极片的制备
将正极活性材料LiNi 0.5Co 0.2Mn 0.3O 2(NCM523)、导电剂炭黑(Super P)、粘结剂聚偏二氟乙烯(PVDF)按质量比96.2:2.7:1.1在适量的溶剂N-甲基吡咯烷酮(NMP)中混合均匀，得到正极浆料，将正极浆料涂布于正极集流体铝箔上，通过烘干、冷压、分条、裁切等工序，得到正极极片。
2、负极极片的制备
将负极活性材料人造石墨、导电剂炭黑(Super P)、粘结剂丁苯橡胶(SBR)和羧甲 基纤维素钠(CMC-Na)按质量比96.4:0.7:1.8:1.1在适量的溶剂去离子水中混合均匀，得到负极浆料，将负极浆料涂布于负极集流体铜箔上，通过烘干、冷压、分条、裁切等工序，得到负极极片。
3、电解液的制备
将碳酸亚乙酯(EC)和碳酸甲乙酯(EMC)按质量比30:70进行混合，得到有机溶剂，将充分干燥的电解质盐LiPF 6溶解于上述混合溶剂中，电解质盐的浓度为1.0mol/L，混合均匀后获得电解液。
4、隔离膜
隔离膜采用如上所述方法制得的隔离膜1。
5、二次电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极极片之间起到隔离的作用，然后卷绕得到电极组件；将电极组件置于外包装中，将上述制备好的电解液注入到干燥后的二次电池中，经过真空封装、静置、化成、整形等工序，获得二次电池。
实施例2-32和对比例1-2的二次电池与实施例1的二次电池的制备方法相似，不同点在于使用了不同的隔离膜，具体详见表1和表2。
三、性能测试方法
1、45℃循环性能
在45℃下，将实施例和对比例制备得到的二次电池以1C倍率恒流充电至充电截止电压4.2V，之后恒压充电至电流≤0.05C，静置30min，再以0.33C倍率恒流放电至放电截止电压2.8V，静置30min，记录此时的电池容量C0。按照此方法对电池进行1500次循环充放电，记录1500次循环后的电池容量记为C1。
电池在45℃下的循环容量保持率＝C1/C0×100％。
2.热蔓延性能
在25℃下，将实施例和对比例制备得到的二次电池以1C倍率恒流充电至充电截止电压4.2V，之后恒压充电至电流≤0.05C，静置10min；然后在电池表面紧贴一块金属加热板，在电池的不接触加热板的位置用夹具加紧电池，并在夹具与电池间加入3mm隔热垫，200℃恒温加热至电池发生热失控；记录电池发生热失控的时间。
3.Crack SOH(State of Health)测试
在25℃下，将各实施例和对比例制备得到的二次电池以0.5C倍率恒流充电至充电截 止电压4.25V，之后恒压充电至电流≤0.05C，静置30min，再以0.33C倍率恒流放电至放电截止电压2.8V，静置30min，记录此时的电池容量C0。
按照此方法对电池进行循环充放电测试，当电池容量在C0的基础上每衰减1％时，将电池进行X-ray CT测试(X射线计算机断层扫描)，当观察到电池正极极片或负极极片拐角处发生断裂时，记录此时的电池容量C1。
Crack SOH＝C1/C0×100％
表1和表2中给出了测得的各实施例和对比例的电池性能。
Figure PCTCN2020132953-appb-000001
Figure PCTCN2020132953-appb-000002
Figure PCTCN2020132953-appb-000003
Figure PCTCN2020132953-appb-000004
由表1可见，相对于对比例1-2，通过使第一种有机颗粒的数均粒径以及凸起的平均高度与无机颗粒层的厚度的比在本申请限定的范围内，能够显著提高电池的循环容量保持率、Crack SOH改善和热蔓延时间，改善电池的循环性能和安全性能。尤其是，通过进一步优化第一种有机颗粒的数均粒径、凸起的平均高度与无机颗粒层的厚度的比，能够进一步提高电池的循环性能和安全性能。由表2可见，使用第二种有机颗粒并优化其数均粒径等参数可以更进一步地改善电池的循环性能和安全性能。
发明人还采用了本申请范围内的无机颗粒、第一种有机颗粒和第二种有机颗粒的其他用量和材质、其他基材、其他涂布工艺参数和其他工艺条件进行了实验，并且获得了与实施例1-32类似的改善电池的循环性能和安全性能的效果。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (28)

  1. 一种隔离膜，其包括：
    基材；和
    设置在所述基材至少一个表面上的涂层；
    所述涂层包括有机颗粒和无机颗粒，所述有机颗粒包括第一种有机颗粒，所述无机颗粒形成无机颗粒层，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起；
    所述所述第一种有机颗粒的数均粒径≥12μm；
    所述凸起的平均高度与所述无机颗粒层的厚度的比≥4。
  2. 根据权利要求1所述的隔离膜，其中，所述凸起的平均高度与所述无机颗粒层的厚度的比为4-20，可选为5-15。
  3. 根据权利要求1-2中任一项所述的隔离膜，其中，所述凸起的平均高度≥10μm，可选为12μm-18μm。
  4. 根据权利要求1-3中任一项所述的隔离膜，其中，所述第一种有机颗粒的数均粒径为15μm-25μm。
  5. 根据权利要求1-4任一项所述的隔离膜，其中，所述第一种有机颗粒为二次颗粒。
  6. 根据权利要求1-5任一项所述的隔离膜，其中，所述第一种有机颗粒包括含氟烯基单体单元的均聚物或共聚物，烯烃基单体单元的均聚物或共聚物，不饱和腈类单体单元的均聚物或共聚物，环氧烷类单体单元的均聚物或共聚物，以及上述各均聚物或共聚物的改性化合物中的一种或几种；
    可选地，所述第一种有机颗粒包括聚四氟乙烯、聚三氟氯乙烯、聚氟乙烯、聚偏二氟乙烯、聚乙烯、聚丙烯、聚丙烯腈、聚环氧乙烷、不同含氟烯基单体单元的共聚物、含氟烯基单体单元与烯烃基单体单元的共聚物、含氟烯基单体单元与丙烯酸类单体单元的共聚物、含氟烯基单体单元与丙烯酸酯类单体单元的共聚物，以及上述各均聚物或共聚物的改性化合物中的一种或几种。
  7. 根据权利要求1-6任一项所述的隔离膜，其中，所述第一种有机颗粒包括偏二氟乙烯-三氟乙烯共聚物、偏二氟乙烯-六氟丙烯共聚物、偏二氟乙烯-三氟乙烯-六氟丙烯共聚物、偏二氟乙烯-六氟丙烯-丙烯酸共聚物、偏二氟乙烯-六氟丙烯-丙烯酸酯共聚物，以及上述共聚物的改性化合物中的一种或几种。
  8. 根据权利要求1-7任一项所述的隔离膜，其中，所述隔离膜满足下述(1)-(2) 中的至少一项：
    (1)所述第一种有机颗粒在所述涂层中的质量占比≥12％，可选为15％-25％；
    (2)所述无机颗粒在所述涂层中的质量占比≤85％，可选为60％-75％。
  9. 根据权利要求1-8任一项所述的隔离膜，其中，所述有机颗粒还包括第二种有机颗粒，所述第二种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起，且所述第二种有机颗粒为一次颗粒。
  10. 根据权利要求9所述的隔离膜，其中，所述第二种有机颗粒的数均粒径≤10μm，且所述第二种有机颗粒的数均粒径≥2μm；可选地，所述第二种有机颗粒的数均粒径为2.5μm-6μm。
  11. 根据权利要求9-10任一项所述的隔离膜，其中，所述第二种有机颗粒在所述涂层中的质量占比为10％以下，可选为2％-10％。
  12. 根据权利要求9-11任一项所述的隔离膜，其中，所述第二种有机颗粒包括丙烯酸酯类单体单元的均聚物或共聚物，丙烯酸类单体单元的均聚物或共聚物，苯乙烯类单体单元的均聚物或共聚物，聚氨酯类化合物，橡胶类化合物，以及上述各均聚物或共聚物的改性化合物中的一种或几种；
    可选地，所述第二种有机颗粒包括丙烯酸酯类单体单元与苯乙烯类单体单元的共聚物，丙烯酸类单体单元与苯乙烯类单体单元的共聚物，丙烯酸类单体单元-丙烯酸酯类单体单元-苯乙烯类单体单元的共聚物，苯乙烯类单体单元与不饱和腈类单体单元的共聚物，苯乙烯类单体单元-烯烃基单体单元-不饱和腈类单体单元的共聚物，以及上述共聚物的改性化合物中的一种或几种。
  13. 根据权利要求9-12任一项所述的隔离膜，其中，所述第二种有机颗粒包括丙烯酸丁酯-苯乙烯共聚物、甲基丙烯酸丁酯-甲基丙烯酸异辛酯共聚物、甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸酯-甲基丙烯酸-苯乙烯共聚物、丙烯酸甲酯-甲基丙烯酸异辛酯-苯乙烯共聚物、丙烯酸丁酯-丙烯酸异辛酯-苯乙烯共聚物、丙烯酸丁酯-甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸丁酯-甲基丙烯酸异辛酯-苯乙烯共聚物、甲基丙烯酸丁酯-丙烯酸异辛酯-苯乙烯共聚物、苯乙烯-丙烯腈共聚物、苯乙烯-丁二烯-丙烯腈共聚物、丙烯酸甲酯-苯乙烯-丙烯腈共聚物、甲基丙烯酸异辛酯-苯乙烯-丙烯腈共聚物、苯乙烯-醋酸乙烯酯共聚物、苯乙烯-醋酸乙烯酯-吡咯烷酮共聚物，以及上述共聚物的改性化合物中的一种或几种。
  14. 根据权利要求1-13中任一项所述的隔离膜，其中，所述无机颗粒层的厚度≤5μm， 可选为1μm-3μm。
  15. 根据权利要求1-14中任一项所述的隔离膜，其中，所述无机颗粒的体积平均粒径Dv 50为0.5μm-2.5μm，可选为0.5μm-1μm。
  16. 根据权利要求1-15中任一项所述的隔离膜，其中，所述无机颗粒包括勃姆石(γ-AlOOH)、氧化铝(Al 2O 3)、硫酸钡(BaSO 4)、氧化镁(MgO)、氢氧化镁(Mg(OH) 2)、二氧化硅(SiO 2)、二氧化锡(SnO 2)、氧化钛(TiO 2)、氧化钙(CaO)、氧化锌(ZnO)、氧化锆(ZrO 2)、氧化钇(Y 2O 3)、氧化镍(NiO)、氧化铈(CeO 2)、钛酸锆(SrTiO 3)、钛酸钡(BaTiO 3)、氟化镁(MgF 2)中的一种或几种。
  17. 根据权利要求1至16中任一项所述的隔离膜，其中，所述隔离膜满足下述(1)-(5)中的一个或几个：
    (1)所述隔离膜的透气度为100s/100mL-300s/100mL；可选地，所述隔离膜的透气度为150s/100mL-250s/100mL；
    (2)所述隔离膜的横向拉伸强度(MD)为1500kg/cm 2-3000kg/cm 2；可选地，所述隔离膜的横向拉伸强度为1800kg/cm 2-2500kg/cm 2；
    (3)所述隔离膜的纵向拉伸强度(TD)为1000kg/cm 2-2500kg/cm 2；可选地，所述隔离膜的纵向拉伸强度为1400kg/cm 2-2000kg/cm 2；
    (4)所述隔离膜的横向断裂伸长率为50％-200％；可选地，所述隔离膜的横向断裂伸长率为100％-150％；
    (5)所述隔离膜的纵向断裂伸长率为50％-200％；可选地，所述隔离膜的纵向断裂伸长率为100％-150％。
  18. 根据权利要求1-17中任一项所述的隔离膜，其中，所述无机颗粒和所述有机颗粒在所述涂层中形成不均匀的孔道结构。
  19. 根据权利要求1-18中任一项所述的隔离膜，其中，任意相邻的两个无机颗粒之间的间距记为L1，任意相邻的一个无机颗粒和一个有机颗粒之间的间距记为L2，则L1＜L2。
  20. 一种制备如权利要求1-19中任一项所述的隔离膜的方法，所述方法至少包括以下步骤：
    (1)提供基材；
    (2)提供涂层浆料，所述涂层浆料包括组分材料和溶剂，所述组分材料包括有机颗粒和无机颗粒，所述有机颗粒包括第一种有机颗粒；
    (3)将步骤(2)所述的涂层浆料涂布在步骤(1)所述的基材的至少一侧，形成涂层并干燥，得到所述隔离膜；
    其中，所述隔离膜包括：基材和设置在所述基材至少一个表面上的涂层；所述涂层包括有机颗粒和无机颗粒，所述有机颗粒包括第一种有机颗粒，所述无机颗粒形成无机颗粒层，所述第一种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起；所述第一种有机颗粒的数均粒径≥12μm；所述凸起的平均高度与所述无机颗粒层的厚度的比≥4。
  21. 根据权利要求20所述的制备方法，其中，在所述步骤(2)中，所述有机颗粒还包括第二种有机颗粒，所述第二种有机颗粒嵌入所述无机颗粒层中且在所述无机颗粒层表面形成凸起，且所述第二种有机颗粒为一次颗粒。
  22. 根据权利要求21所述的制备方法，其中，所述第二种有机颗粒的数均粒径≤10μm，且所述第二种有机颗粒的数均粒径≥2μm；可选地，所述第二种有机颗粒的数均粒径为2.5μm-6μm。
  23. 根据权利要求21-22任一项所述的方法，其中，所述第二种有机颗粒的加入质量占所述组分材料的干重总和的10％以下，可选为2％-10％。
  24. 根据权利要求20-23任一项所述的方法，其中，所述方法满足下述(1)-(7)中的一个或几个：
    (1)在所述步骤(2)中，所述第一种有机颗粒的加入质量占所述组分材料的干重总和的12％以上；可选为12％-30％；
    (2)在所述步骤(2)中，所述涂层浆料的固含量为28％-45％，可选为30％-38％，基于重量计；
    (3)在所述步骤(3)中，所述涂布采用涂布机进行，所述涂布机包括凹版辊，所述凹版辊的线数为100LPI-300LPI，可选为125LPI-190LPI；
    (4)在所述步骤(3)中，所述涂布的速度为30m/min-90m/min，可选为50m/min-70m/min；
    (5)在所述步骤(3)中，所述涂布的线速比为0.8-2.5，可选为0.8-1.5；
    (6)在所述步骤(3)中，所述干燥的温度为40℃-70℃，可选为50℃-60℃；
    (7)在所述步骤(3)中，所述干燥的时间为10s-120s，可选为20s-80s。
  25. 一种二次电池，其包括根据权利要求1至19中任一项所述的隔离膜或根据权利要求20-24任一项所述的制备方法得到的隔离膜。
  26. 一种电池模块，包括根据权利要求25所述的二次电池。
  27. 一种电池包，包括根据权利要求26所述的电池模块。
  28. 一种装置，包括根据权利要求25所述的二次电池、根据权利要求26所述的电池模块、或根据权利要求27所述的电池包中的至少一种。
PCT/CN2020/132953 2020-11-30 2020-11-30 一种隔离膜、含有它的二次电池及其相关的电池模块、电池包和装置 WO2022110225A1 (zh)

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