WO2022205165A1 - 一种隔离膜及包含所述隔离膜的电化学装置和电子装置 - Google Patents

一种隔离膜及包含所述隔离膜的电化学装置和电子装置 Download PDF

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WO2022205165A1
WO2022205165A1 PCT/CN2021/084667 CN2021084667W WO2022205165A1 WO 2022205165 A1 WO2022205165 A1 WO 2022205165A1 CN 2021084667 W CN2021084667 W CN 2021084667W WO 2022205165 A1 WO2022205165 A1 WO 2022205165A1
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Prior art keywords
separator
polymer
coating
coating layer
present application
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PCT/CN2021/084667
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English (en)
French (fr)
Inventor
冯波
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to PCT/CN2021/084667 priority Critical patent/WO2022205165A1/zh
Priority to CN202410311457.8A priority patent/CN118213710A/zh
Priority to EP21933830.8A priority patent/EP4318777A4/en
Priority to KR1020237031941A priority patent/KR102897174B1/ko
Priority to JP2023558865A priority patent/JP7776523B2/ja
Priority to CN202410308749.6A priority patent/CN118213709A/zh
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Priority to BR112023019627A priority patent/BR112023019627A2/pt
Priority to CN202180004513.8A priority patent/CN114144932B/zh
Publication of WO2022205165A1 publication Critical patent/WO2022205165A1/zh
Priority to US18/476,840 priority patent/US20240079727A1/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
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    • 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
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    • 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
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
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    • 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
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
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    • H01M50/431—Inorganic material
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    • 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
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    • 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
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    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
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    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
    • H—ELECTRICITY
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    • 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
    • H01M50/491—Porosity
    • H—ELECTRICITY
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    • 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
    • H01M50/497—Ionic conductivity
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the technical field of lithium ion batteries, and in particular, to a separator and an electrochemical device and an electronic device including the separator.
  • the separator is one of the key inner layer components.
  • the performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle and safety performance of the battery.
  • the separator with excellent performance plays an important role in improving the overall performance of the battery.
  • the main function of the separator is to separate the positive and negative electrodes of the battery to prevent short circuit due to contact between the two electrodes, and also has the function of allowing electrolyte ions to pass through.
  • Existing lithium-ion battery separators are usually coated separators, but the existing coated separators often cannot meet the requirements of high adhesion and high dynamic performance at the same time. Coated separator for junctional and dynamic properties.
  • the purpose of the present application is to provide a separator and an electrochemical device and an electronic device comprising the separator, so as to improve the rate performance and cycle performance of lithium ion batteries, especially the rate performance and cycle performance under low temperature conditions.
  • the specific technical solutions are as follows:
  • the present application is explained by taking a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery.
  • a first aspect of the present application provides a separator, comprising a substrate and a first coating layer disposed on at least one surface of the substrate, wherein the first coating layer comprises a first polymer, and the surface of the first coating layer has a first coating layer.
  • the number of the first polymer particles whose maximum length is between 10 ⁇ m and 30 ⁇ m is 10 to 30, preferably 20 to 30.
  • the separator of the present application is observed under a magnification of 500 times by SEM (Scanning Electron Microscope), and the maximum length of the first polymer particles in any 250 ⁇ m ⁇ 200 ⁇ m area (that is, the area that can be observed by an eyepiece) is between 10 ⁇ m and 10 ⁇ m.
  • the number of particles between 30 ⁇ m is between 10 and 30.
  • the first coating layer of the present application is provided on at least one surface of the release film substrate.
  • the first coating layer can be arranged on one surface of the release film substrate, or the first coating layer can be arranged on two surfaces of the release film substrate. on a surface.
  • the positive electrode in the present application may specifically refer to a positive electrode pole piece, and the negative electrode may specifically refer to a negative electrode pole piece.
  • the gas permeability value P of the separator is 500sec/100mL to 10000sec/100mL, preferably 1000sec/100mL to 5000sec/100mL.
  • the air permeability value P of the separator is too high (for example, higher than 10000sec/100mL)
  • the internal resistance of the lithium ion battery increases, which will affect the rate discharge performance of the battery, especially the rate discharge performance at low temperature
  • the value P is too low (for example, less than 500sec/100mL)
  • the air permeability of the separator is good, the hardness of the corresponding cell (lithium-ion battery) is low, and soft cells are prone to appear.
  • the coating areal density W1 of the first coating layer of the separator is 0.4g/m 2 to 2 g/m 2 , preferably, the coating areal density W1 of the first coating layer is 0.4 g/m m 2 to 1 g/m 2 .
  • the coating surface density W1 of the first coating when the coating surface density W1 of the first coating is too low (for example, lower than 0.4 g/m 2 ), the adhesion between the interfaces will be insufficient, and the adhesion performance of the coating will decrease; when the first coating is When the coating areal density W1 is too high (for example, higher than 2 g/m 2 ), the relative content of the electrode active material in the lithium ion battery decreases, which affects the energy density of the lithium ion battery.
  • the coating surface density W1 of the first coating of the present application By controlling the coating surface density W1 of the first coating of the present application to be within the above range, the separator and the electrode sheet can have excellent interfacial bonding performance, which has little effect on the energy density of the lithium ion battery.
  • the porosity K of the separator is 30% to 65%.
  • the porosity K of the separator is too low (for example, lower than 30%), it is difficult for the electrolyte to infiltrate the separator, which affects the ion transport capacity of the separator; when the porosity K of the separator is too high (for example, higher than 65%), the separator becomes loose and the strength decreases, which affects the puncture resistance of the separator.
  • the separator can have excellent ion transport capability and strength.
  • the release film further includes a heat-resistant layer, and the heat-resistant layer may be disposed between the substrate and the first coating layer.
  • the heat-resistant layer includes inorganic particles, and the Dv50 of the inorganic particles is 0.5 ⁇ m to 35 ⁇ m, preferably 5 ⁇ m to 35 ⁇ m.
  • the separator can have high energy density and excellent dynamic performance.
  • the thickness of the heat-resistant layer is not particularly limited in the present application, for example, it can be 0.6 ⁇ m to 40 ⁇ m, as long as the heat-resistant layer meets the requirements of the present application.
  • Inorganic particles include boehmite, magnesium hydroxide, aluminum oxide, titanium dioxide, silicon dioxide, zirconium dioxide, and tin dioxide. , at least one of magnesium oxide, zinc oxide, barium sulfate, boron nitride or aluminum nitride.
  • the density is low, resulting in poor adhesion between the separator and the pole piece, which affects the hardness of the lithium-ion battery and easily leads to soft cells; when the ratio of the air permeability value P of the separator to the surface density W1 of the first coating is too high (for example P/W1 is higher than 6500), indicating that the separator has high air permeability, poor air permeability, and high surface density of the first coating, which leads to an increase in the internal resistance of the lithium-ion battery and affects the rate performance of the battery, especially at low temperatures. rate performance.
  • the ratio of the gas permeability value P of the separator to the surface density W1 of the first coating layer within the above range, the lithium ion battery can have excellent rate performance, especially the rate performance at low temperature.
  • the separator When the density is high, it is difficult for the electrolyte to infiltrate the separator, which affects the ion transport capacity of the separator; when the ratio of the porosity K of the separator to the surface density W1 of the first coating is too high (for example, K/W1 is lower than 1.4), it indicates that the separator is isolated
  • the porosity of the membrane is high, the surface density of the first coating is low, the isolation membrane becomes loose, and the strength decreases, which affects the puncture resistance of the isolation membrane.
  • the first coating layer further includes a first auxiliary binder, and the mass ratio of the first polymer to the first auxiliary binder is 2.5 to 18.
  • the mass ratio of the first polymer to the first auxiliary binder is too low (for example, lower than 2.5)
  • the content of the first polymer decreases, so that the gap caused by the particulate first polymer decreases , affecting the transport of the electrolyte between the interface of the first coating and the adhesion between the first coating and the electrode sheet
  • the mass ratio of the first polymer to the first auxiliary binder is too high (for example, high In 18)
  • the cohesion of the first coating is low, and the bonding performance of the first polymer will decrease with the decrease of the cohesion of the first coating.
  • the first auxiliary binder in the present application may include ethyl acrylate, butyl acrylate, ethyl methacrylate, styrene, chlorostyrene, fluorostyrene, methyl methacrylate, etc. at least one of styrene, acrylic acid, methacrylic acid, maleic acid, acrylonitrile or butadiene.
  • the isolation film further includes a second coating layer, and the first coating layer and the second coating layer may be respectively disposed on both sides of the isolation film.
  • the second coating layer includes a second polymer and a second auxiliary binder, and the mass ratio of the second polymer to the second auxiliary binder is 5 to 20.
  • the mass ratio of the second polymer to the second auxiliary binder is too low (for example, lower than 5)
  • the content of the second polymer decreases, which affects the adhesion between the second coating and the electrode sheet.
  • the mass ratio of the second polymer to the second auxiliary binder is too high (for example, higher than 20), the cohesion of the second coating is low, and the adhesion performance of the second coating decreases.
  • the mass ratio of the second polymer to the second auxiliary binder within the above-mentioned range, the second coating layer and the electrode sheet can have excellent adhesion.
  • the side of the separator with the first coating can be in contact with the positive pole piece, and the side of the separator with the second coating can be in contact with the negative pole piece, so that the space between the separator and the positive pole piece and the negative pole piece is even It has excellent bonding effect, and has better electrolyte wettability between the separator and the positive electrode, thereby improving the low temperature performance of the lithium ion battery.
  • the separator of the present application has lithium ion permeability and electron barrier properties.
  • the adhesive strength of the first coating layer facing the positive electrode is 4 N/m to 20 N/m, indicating that the first coating layer has excellent adhesive performance with the positive electrode sheet.
  • the adhesive strength of the second coating layer when it faces the negative electrode is 4 N/m to 20 N/m, indicating that the second coating layer has excellent adhesive performance with the negative electrode pole piece.
  • the mass percentage content of the first polymer is 85% to 95%, and the mass percentage content of the first auxiliary binder is 5% to 50%. 15%.
  • the softening point of the first polymer is from 90°C to 150°C, preferably from 110°C to 150°C.
  • the softening point of the first polymer when the softening point of the first polymer is too high (for example, higher than 150°C), the first polymer is not easy to soften when heated, and the formed bonding area is small, which affects the first coating and the electrode. Cohesion between sheets; when the softening point of the first polymer is too low (eg, lower than 90° C.), the first polymer tends to block the pores of the coating/separator after softening, affecting the kinetic performance of the lithium-ion battery.
  • the first polymer By controlling the softening point of the first polymer of the present application to be within the above range, the first polymer can have excellent bonding properties, thereby improving the bonding force between the first coating and the electrode sheet.
  • the term "softening point" refers to the temperature at which a substance softens.
  • the Dv50 of the first polymer is 3 ⁇ m to 16 ⁇ m, and is not limited to any theory. When the Dv50 of the first polymer is too small (for example, less than 3 ⁇ m), the interfacial distance between the separator and the electrode sheet is too small, and the ability to transport the electrolyte solution is reduced.
  • the Dv50 of the first polymer is too large (for example, greater than 16 ⁇ m), the gap brought by the granular first polymer is too large, which will also affect the adhesion between the separator and the electrode sheet.
  • the Dv50 of the first polymer of the present application By controlling the Dv50 of the first polymer of the present application within the above-mentioned range, a first polymer excellent in adhesiveness can be obtained.
  • the coated areal density W2 of the second coating layer of the separator is 0.1 g/m 2 to 1 g/m 2 .
  • the coating surface density W2 of the second coating is too low (for example, lower than 0.1 g/m 2 )
  • the adhesion between the interfaces will be insufficient, and the adhesion performance of the coating will decrease
  • the coating areal density W2 is too high (for example, higher than 1 g/m 2 )
  • the separator and the electrode sheet can have excellent interfacial bonding performance, and the rate performance of the lithium ion battery is less affected.
  • the mass percentage content of the second polymer is 88% to 92.5%, and the mass percentage content of the second auxiliary binder is 7.5% to 7.5%. 12%.
  • the first polymer comprises a homopolymer of vinylidene fluoride, hexafluoropropylene, ethylene, propylene, vinyl chloride, propylene chloride, acrylic acid, acrylates, styrene, butadiene, and acrylonitrile at least one of a compound or a copolymer.
  • the second polymer is not particularly limited in the present application, as long as it meets the requirements of the present application, for example, the second polymer may include ethyl acrylate, butyl acrylate, ethyl methacrylate, styrene, chlorostyrene, fluorostyrene , at least one of methylstyrene, acrylic acid, methacrylic acid, maleic acid, acrylonitrile or butadiene.
  • the Dv50 of the second polymer is 0.2 ⁇ m to 8 ⁇ m, and by controlling the Dv50 of the second polymer within the above range, a second polymer with excellent adhesion can be obtained.
  • the second auxiliary binder is not particularly limited in the present application, as long as the requirements of the present application are met.
  • the second auxiliary binder may include at least one of sodium carboxymethyl cellulose or dimethylsiloxane.
  • the preparation method of the first polymer of the present application is not particularly limited, and the preparation method of those skilled in the art can be adopted, for example, the following preparation method can be adopted:
  • the reaction kettle was evacuated, and nitrogen was evacuated to replace oxygen. Then, deionized water, vinylidene fluoride (VDF), emulsifier perfluoroalkyl carboxylate, and chain transfer agent isopropanol were added to the reaction kettle containing the stirrer until the reaction was carried out.
  • the pressure of the kettle is about 3.5MPa. Then the temperature was raised to 50°C to 70°C, the stirring speed was 70r/min to 100r/min, and the polymerization reaction was started. At the same time, the vinylidene fluoride monomer was continuously added to maintain the pressure of the reactor at 3.5MPa, until the solid content of the emulsion in the reactor reached 25%. The reaction is stopped at 30%, the unreacted monomer is recovered, the polymer emulsion is released, and the first polymer is obtained after centrifugation, washing and drying.
  • VDF vinylidene fluoride
  • emulsifier perfluoroalkyl carboxylate chain transfer agent
  • the initiator in the present application, as long as it can initiate the polymerization of the monomer, for example, it can be dicumyl hydroperoxide.
  • the amount of monomers, deionized water, initiators, and chain transfer agents added in this application as long as the added monomers can be polymerized.
  • deionized water is 5 to 10 times the mass of the monomers.
  • the initiator accounts for 0.05% to 0.5% of the mass of the monomer
  • the emulsifier accounts for 0.1% to 1% of the mass of the monomer
  • the chain transfer agent accounts for 3% to 7% of the mass of the monomer.
  • the present application also does not have any special restrictions on the preparation methods of the first auxiliary binder, the second polymer and the second auxiliary binder, and the preparation methods commonly used by those skilled in the art can be used, and the selection can be made according to the different types of monomers used. , such as solution method, slurry method, gas phase method, etc.
  • the positive electrode sheet in the present application is not particularly limited, as long as the purpose of the present application can be achieved.
  • a positive electrode sheet typically includes a positive electrode current collector and a positive electrode active material layer.
  • the positive electrode current collector is not particularly limited, and can be any positive electrode current collector in the art, such as aluminum foil, aluminum alloy foil, or composite current collector.
  • the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material is not particularly limited, and any positive electrode active material in the art can be used, for example, it can include nickel cobalt lithium manganate (811, 622, 523, 111), nickel cobalt lithium aluminate , at least one of lithium iron phosphate, lithium-rich manganese-based material, lithium cobaltate, lithium manganate, lithium iron manganese phosphate or lithium titanate.
  • a negative electrode sheet typically includes a negative electrode current collector and a negative electrode active material layer.
  • the negative electrode current collector is not particularly limited, and any negative electrode current collector in the art can be used, such as copper foil, aluminum foil, aluminum alloy foil, and composite current collector.
  • the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material is not particularly limited, and any negative electrode active material in the art can be used.
  • at least one of artificial graphite, natural graphite, mesocarbon microspheres, soft carbon, hard carbon, silicon, silicon carbon, lithium titanate, and the like may be included.
  • the base material of the separator of the present application includes, but is not limited to, at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polyimide or aramid.
  • the polyethylene includes at least one component selected from the group consisting of high density polyethylene, low density polyethylene, and ultra-high molecular weight polyethylene.
  • polyethylene and polypropylene they have an excellent effect on preventing short circuits and can improve the stability of lithium-ion batteries through the shutdown effect.
  • the lithium ion battery of the present application further includes an electrolyte, and the electrolyte may be one or more of a gel electrolyte, a solid electrolyte, and an electrolyte, and the electrolyte includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is selected from LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2.
  • LiC(SO 2 CF 3 ) 3 LiSiF 6 , LiBOB and lithium difluoroborate.
  • LiPF 6 may be chosen as the lithium salt because it gives high ionic conductivity and improves cycling characteristics.
  • the non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents, or a combination thereof.
  • the above-mentioned carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound, or a combination thereof.
  • Examples of the above-mentioned chain carbonate compounds are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), carbonic acid Methyl ethyl ester (MEC) and combinations thereof.
  • Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), and combinations thereof.
  • fluorocarbonate compounds are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethyl carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-dicarbonate Fluoro-1-methylethylene, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate Ethyl carbonate 1,1,2,2-tetrafluoroethylene carbonate
  • 1-fluoro-2-methylethylene carbonate 1-fluoro-1-methylethylene carbonate
  • 1,2-dicarbonate Fluoro-1-methylethylene 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethyl
  • carboxylate compounds are methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone , caprolactone, valerolactone, mevalonolactone, caprolactone, and combinations thereof.
  • ether compounds examples include dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethyl ether Oxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.
  • Examples of the above-mentioned other organic solvents are dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, Formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters and combinations thereof.
  • a second aspect of the present application provides an electrochemical device comprising the separator in any of the above embodiments, having excellent low temperature rate performance and low temperature cycle performance.
  • a third aspect of the present application provides an electronic device comprising the electrochemical device described in the above embodiments of the present application, which has excellent low temperature rate performance and low temperature cycle performance.
  • electronic devices may include, but are not limited to, notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, assisted bicycles, bicycles, Lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large-scale household storage batteries and lithium-ion capacitors, etc.
  • a lithium ion battery can be manufactured by the following process: the positive electrode and the negative electrode are overlapped through a separator, and they are wound, folded, etc., and placed into the case as required, and the electrolyte is injected into the case and sealed, wherein the separator used The above-mentioned separator provided in this application.
  • an overcurrent preventing element, a guide plate, etc. can also be placed in the case as required, so as to prevent pressure rise and overcharge and discharge inside the lithium ion battery.
  • air permeability value refers to the time required for 100ml of air to pass through the separator.
  • Dv50 means particles The cumulative distribution is a particle size of 50%, that is, the volume content of particles smaller than this particle size accounts for 50% of all particles.
  • the present application provides a separator, an electrochemical device and an electronic device comprising the separator, comprising a substrate and a first coating disposed on at least one surface of the substrate, wherein the first coating comprises a first polymer , in any area of 250 ⁇ m ⁇ 200 ⁇ m on the surface of the first coating layer, the number of the first polymer particles whose maximum length is between 10 ⁇ m and 30 ⁇ m is 10 to 30.
  • the separator of the present application has excellent interfacial bonding performance, improves the structural stability of the lithium ion battery, and enables the lithium ion battery to have better charge-discharge performance, especially the rate performance and cycle performance under low temperature conditions.
  • Fig. 1 is the structural schematic diagram of the isolation membrane of the first embodiment of the application
  • FIG. 2 is a schematic structural diagram of the isolation film of the second embodiment of the application.
  • FIG. 3 is a schematic structural diagram of the isolation film of the third embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of the isolation film according to the fourth embodiment of the present application.
  • the present application is explained by taking a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery.
  • the isolation film of the present application includes a substrate 1 and a first coating layer 2 disposed on one surface of the substrate 1 .
  • a first coating 2 is provided on one surface of the substrate 1, and a second coating 3 is provided on the other surface, wherein the first coating 2 and the substrate 1 are provided A heat-resistant layer 4 is also provided therebetween.
  • the separator includes a substrate 1 , and a first coating layer 2 and a second coating layer 3 respectively disposed on two surfaces of the substrate 1 .
  • the isolation film includes a substrate 1 and a first coating layer 2 respectively disposed on two surfaces of the substrate 1 .
  • the separator coated with the first coating was cut into a 10mm ⁇ 10mm sample, and then the sample was placed under the SEM to observe at a magnification of 500 times, and any five 250 ⁇ m ⁇ 200 ⁇ m areas were selected in the field of view (that is, under an eyepiece). Observed area), record the number of particles with the maximum length of the first polymer particles in the selected area between 10 ⁇ m and 30 ⁇ m, and then take the average value, that is, the first polymer particles in the first coating unit area area Number of particles with a maximum length between 10 ⁇ m and 30 ⁇ m.
  • Disassemble the discharged lithium-ion battery to be tested then take out the separator, soak the separator in N-methylpyrrolidone (NMP) for 30min, then dry it in a fume hood at 25°C for 4 hours, and take out the dried separator Film, in an environment with a temperature of 25 ° C and a humidity of less than 80%, the test sample is made into a size of 4cm ⁇ 4cm, and the air permeability is directly measured by the Gurley test (100mL) method using an air permeability tester (Air-permeability-tester). The value, in seconds (sec), represents the time required for 100 mL of air to pass through a 4cm x 4cm area of the separator.
  • NMP N-methylpyrrolidone
  • the Dv50 of the inorganic particles, the first polymer, and the second polymer were measured using a laser particle size analyzer.
  • the national standard GB/T 2790-1995 is adopted, that is, the 180° peel test standard is used to test the adhesion between the separator and the positive pole piece or negative pole piece, and the separator and the positive pole piece or the negative pole piece are cut into 54.2 mm ⁇ 72.5mm sample, compound the separator with the positive pole piece or the negative pole piece, and use a hot press to hot press.
  • the hot pressing conditions are: temperature 85°C, pressure 1Mpa, and hot pressing time 85s (seconds) The samples were cut into 15mm ⁇ 54.2mm strips, and the adhesive force between the separator and the positive pole piece or the negative pole piece was tested according to the 180° peel test standard.
  • a general-purpose differential scanning calorimeter (DSC) method was used: 5 mg of the first polymer samples prepared in each example and the comparative example were taken, and the temperature was raised to 150 °C at a heating rate of 5 °C/min, and the DSC curve was collected. The DSC curve determines the softening point, ie the softening temperature, of the first polymer.
  • the three-point bending method to test the hardness of the cell operate at 25°C, fully discharge the cell to 3.0V, and use the tabs for insulation protection. Adjust the distance between the support rods under the hardness test fixture of the universal testing machine (Instron-3365) to 2/3 of the width of the cell, and place the cell flat on the lower fixture with the width direction perpendicular to the support rod. Adjust the upper indenter of the fixture to be perpendicular to the width direction and at the center of the cell, press down at a speed of 5mm/min, the upper indenter just begins to contact the cell's recording cell deformation and displacement, when the displacement reaches 1mm , and the force corresponding to the deformation resistance is the hardness of the cell.
  • the lower support rod is arc-shaped with a diameter of 10mm; the upper indenter is arc-shaped with a diameter of 10mm.
  • 2C discharge rate test at 25°C, the formed lithium-ion battery is charged to 4.45V at a constant current rate of 0.2C, and then charged at a constant voltage until the current is less than or equal to 0.05C, and then left for 30 minutes, and then charged at a rate of 0.2C. Constant current discharge to 3.0V, test to obtain 0.2C rate discharge capacity of lithium-ion battery;
  • the lithium-ion battery was charged to 4.45V at a constant current rate of 0.2C, and then charged at a constant voltage until the current was less than or equal to 0.05C, then stood for 30 minutes, and then was discharged to 3.0V at a constant current rate of 2C. Lithium-ion battery 2C rate discharge capacity.
  • Lithium ion secondary battery 2C rate discharge capacity retention rate (%) 2C rate discharge capacity/0.2C rate discharge capacity ⁇ 100%.
  • -20°C 0.2C discharge rate test at 25°C, charge the formed lithium-ion battery to 4.45V at a constant current rate of 0.2C, and then charge it at a constant voltage until the current is less than or equal to 0.05C, then let it stand for 30 minutes, and then Discharge to 3.0V at a constant current rate of 0.2C, and the test obtains the discharge capacity of the lithium-ion battery at a rate of 0.2C at 25°C;
  • Cycle capacity retention rate (discharge capacity at the 500th cycle/discharge capacity at the first cycle) ⁇ 100%.
  • the reaction kettle was evacuated, and after nitrogen was used to replace oxygen, deionized water, vinylidene fluoride (VDF), initiator dicumyl hydroperoxide, and emulsifier perfluoroalkyl carboxylic acid were added to the reaction kettle containing the stirrer.
  • the pressure of salt and chain transfer agent isopropanol to the reactor is 3.5MPa, in which deionized water is 7 times the mass of vinylidene fluoride monomer, the initiator accounts for 0.2% of the mass of vinylidene fluoride monomer, and the emulsifier accounts for vinylidene fluoride monomer.
  • the chain transfer agent accounts for 5% of the mass of the vinylidene fluoride monomer. Then the temperature was raised to 60°C, the speed of the stirrer was 80r/min, and the polymerization reaction was started. At the same time, the vinylidene fluoride monomer was continuously added to maintain the pressure of the reactor at 3.5MPa, and the reaction was stopped until the solid content of the emulsion in the reactor reached 25%, and the unreacted monomer was recovered. body, release the polymer emulsion, after centrifugation, washing and drying, the first polymer is obtained. The softening point of the first polymer was 125°C, and the Dv50 was 12 ⁇ m.
  • the prepared first polymer and the first auxiliary binder (a copolymer formed by mass fraction of 80% styrene, 10% isobutyl acrylate and 10% acrylonitrile, Dv50 is 0.2 ⁇ m)
  • the prepared separator was observed under 500 times magnification by SEM, and in any 250 ⁇ m ⁇ 200 ⁇ m area (unit area area) on the surface of the first coating, the maximum length of the first polymer particles was between 10 ⁇ m and 30 ⁇ m
  • the number of particles is 10 (referred to as the number of particles in Table 1).
  • the positive active material lithium cobaltate, acetylene black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 94:3:3, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75%. ingredients and mix well.
  • the slurry was uniformly coated on one surface of an aluminum foil with a thickness of 12 ⁇ m, dried at 90° C., and after cold pressing, a positive electrode sheet with a thickness of 100 ⁇ m of positive active material layer was obtained, and then on the other surface of the positive electrode sheet.
  • the above steps are repeated to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides. Cut the positive pole piece into a size of 74mm ⁇ 867mm and weld the tabs for later use.
  • the negative active material artificial graphite, acetylene black, styrene-butadiene rubber and sodium carboxymethyl cellulose are mixed in a mass ratio of 96:1:1.5:1.5, and then deionized water is added as a solvent to prepare a slurry with a solid content of 70% , and stir well.
  • the slurry was evenly coated on one surface of a copper foil with a thickness of 8 ⁇ m, dried at 110° C., and after cold pressing, a negative electrode pole piece with a negative electrode active material layer thickness of 150 ⁇ m was obtained on one side coated with a negative electrode active material layer, Then, the above coating steps are repeated on the other surface of the negative electrode pole piece to obtain a negative electrode pole piece coated with a negative electrode active material layer on both sides. Cut the negative pole piece into a size of 74mm ⁇ 867mm and weld the tabs for later use.
  • the non-aqueous organic solvent In an environment with a water content of less than 10 ppm, the non-aqueous organic solvents ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), propyl propionate (PP), vinylene carbonate ( VC) mix according to mass ratio 20:30:20:28:2, then in non-aqueous organic solvent, add lithium hexafluorophosphate (LiPF 6 ) to dissolve and mix uniformly, obtain electrolyte, wherein, LiPF 6 and the mass ratio of non-aqueous organic solvent 8:92.
  • LiPF 6 lithium hexafluorophosphate
  • the above-prepared positive pole piece, separator, and negative pole piece are stacked in sequence, the side of the separator with the first coating is contacted with the positive pole piece, and an electrode assembly is obtained by winding.
  • the electrode assembly is put into an aluminum-plastic film packaging bag, and the moisture is removed at 80 °C, and the prepared electrolyte is injected into the lithium-ion battery through the processes of vacuum packaging, standing, forming, and shaping.
  • the solid content of slurry A was increased, and as shown in Table 1, the maximum length of the first polymer particles in any 250 ⁇ m ⁇ 200 ⁇ m area of the first coating surface was between 10 ⁇ m and 30 ⁇ m. Except for 15 particles, the rest are the same as in Example 1.
  • the solid content of slurry A was increased, and as shown in Table 1, the maximum length of the first polymer particles in any 250 ⁇ m ⁇ 200 ⁇ m area of the first coating surface was between 10 ⁇ m and 30 ⁇ m. Except for 20 particles, the rest are the same as in Example 1.
  • the solid content of slurry A was increased, and as shown in Table 1, the maximum length of the first polymer particles in any 250 ⁇ m ⁇ 200 ⁇ m area of the first coating surface was between 10 ⁇ m and 30 ⁇ m.
  • the number of particles was the same as in Example 1 except for 26 particles.
  • the solid content of slurry A was increased, and as shown in Table 1, the maximum length of the first polymer particles in any 250 ⁇ m ⁇ 200 ⁇ m area of the first coating surface was between 10 ⁇ m and 30 ⁇ m. Except for 30 particles, the rest are the same as in Example 1.
  • Example 2 In addition to adding a heat-resistant layer and a second coating layer in ⁇ Preparation of Separator>, as shown in Table 2-2, adjusting the coating areal density of the first coating layer to 0.4 g/m 2 , ⁇ Preparation of lithium ion battery> Except being different from Example 1, the rest is the same as Example 1.
  • Inorganic particles with a Dv50 of 2 ⁇ m boehmite and polyacrylate were mixed in a mass ratio of 90:10 and uniformly dispersed in deionized water to form a heat-resistant layer slurry with a solid content of 50%, followed by microgravure coating
  • the obtained heat-resistant layer slurry is uniformly coated on one side of the separator substrate to obtain a heat-resistant layer of corresponding thickness, and the drying is completed in an oven.
  • a first coating layer was prepared on the surface of the heat-resistant layer.
  • the second polymer (a copolymer formed by the mass fraction of 80% styrene, 10% isobutyl acrylate, 10% acrylonitrile, Dv50 is 0.2 ⁇ m) and the second auxiliary binder (5.5%
  • the mixture of sodium carboxymethyl cellulose and 94.5% dimethylsiloxane) was added to the mixer according to the mass ratio of 91:9, stirred and mixed evenly, and then added deionized water for stirring, and adjusted the slurry viscosity to 100mPa ⁇ s , the solid content is 12%, and the slurry B is obtained; the slurry B is evenly coated on the other side of the isolation film substrate (that is, the side of the isolation film without the first coating layer), and the coating surface of the second coating layer
  • the density is 0.2 g/m 2 , and drying is completed in an oven to form a separator with a structure as shown in FIG. 2 .
  • the prepared separator was observed under 500 times magnification by SEM, and in any 250 ⁇ m ⁇ 200 ⁇ m area (unit area area) on the surface of the first coating, the maximum length of the first polymer particles was between 10 ⁇ m and 30 ⁇ m
  • the number of particles is 25 (referred to as the number of particles in Table 1 and Table 2-2).
  • the above-prepared positive pole piece, separator, and negative pole piece are stacked in order, the side of the separator with the first coating is in contact with the positive pole piece, and the side of the separator with the second coating is in contact with the negative pole piece , and rolled to obtain an electrode assembly.
  • the electrode assembly is put into an aluminum-plastic film packaging bag, and the moisture is removed at 80 ° C, the prepared electrolyte is injected, and the lithium ion battery is obtained through vacuum packaging, standing, forming, and shaping.
  • Example 7 Example 8, and Example 9 are the same as Example 6, except that in ⁇ Preparation of Separator Film>, the coating areal density of the first coating layer was adjusted as shown in Table 2-2.
  • Example 10 Example 11, Example 12, except that in ⁇ Preparation of First Polymer>, the first polymer was prepared by a method similar to that of (1-1) Preparation of the first polymer in Example 1 , except that the Dv50 of the first polymer was adjusted as shown in Table 2-2, the rest was the same as that of Example 7.
  • Example 13, Example 14, Example 15, and Example 16 were prepared by a method similar to the preparation of (1-1) First polymer in Example 1 except that in ⁇ Preparation of First Polymer>
  • the first polymer was the same as in Example 7 except that the softening point of the first polymer was adjusted as shown in Table 2-2.
  • Example 17 Example 18, Example 19, Example 20, Example 21, except that in ⁇ Preparation of the first coating layer>, the composition and content of the first auxiliary binder were adjusted as shown in Table 2-1 , and the rest are the same as in Example 7.
  • Example 22 Example 23, Example 24, Example 25, Example 26, Example 27, the first polymer was prepared by a method similar to the preparation of the (1-1) first polymer in Example 1 , except that the composition and content of the first polymer were adjusted as shown in Table 2-1, the rest were the same as in Example 7.
  • Example 28 Example 29, Example 30, Example 31, Example 32, and Example 33, except that in ⁇ Preparation of Heat Resistant Layer>, the composition and Dv50 of the inorganic particles were adjusted as shown in Table 2-2 , and the rest are the same as in Example 7.
  • Example 34 and Example 35 except that in ⁇ Preparation of Second Coating>, the composition and content of the second polymer and the second auxiliary binder were adjusted as shown in Table 2-1, the rest were the same as those in Example 7. same.
  • Example 41, Example 42, and Example 43 were the same as Example 7 except that in ⁇ Preparation of Second Coating Layer>, the coating areal density of the second coating layer was adjusted as shown in Table 2-2.
  • Example 44 was the same as Example 7 except that in ⁇ Preparation of the first coating layer>, the second coating layer was not provided on the surface of the separator.
  • Example 45 is the same as Example 7 except that in ⁇ Preparation of the first coating layer>, no heat-resistant layer is provided between the first coating layer and the release film substrate.
  • the solid content of Slurry A is reduced, as shown in Table 2-2, so that the maximum length of the first polymer particles in any 250 ⁇ m ⁇ 200 ⁇ m area of the first coating surface is within 10 ⁇ m to 30 ⁇ m
  • the number of particles in between is the same as in Example 7 except for 10.
  • the first polymer was prepared by a method similar to (1-1) Preparation of the first polymer in Example 1, and the first polymer was 80% by mass of styrene, 10 A copolymer formed by the polymerization of % isobutyl acrylate and 10% acrylonitrile, the first auxiliary binder is a mixture composed of 5.5% sodium carboxymethyl cellulose and 94.5% dimethylsiloxane in mass fraction, the first polymer The mass ratio to the second polymer is 91:9, so that the number of particles with the maximum length of the first polymer particles between 10 ⁇ m and 30 ⁇ m in any 250 ⁇ m ⁇ 200 ⁇ m area on the surface of the first coating layer is 0, and the rest are the same as the examples 1 is the same.
  • the first polymer was prepared by a method similar to (1-1) Preparation of the first polymer in Example 1, and the first polymer was 80% by mass of styrene, 10 A copolymer formed by the polymerization of % isobutyl acrylate and 10% acrylonitrile, the first auxiliary binder is a mixture composed of 5.5% sodium carboxymethyl cellulose and 94.5% dimethylsiloxane in mass fraction, the first polymer The mass ratio to the second polymer is 91:9.
  • the number of particles with the maximum length of the first polymer particles ranging from 10 ⁇ m to 30 ⁇ m in any 250 ⁇ m ⁇ 200 ⁇ m area on the surface of the first coating layer is 0 Except for one, the rest is the same as that of Example 7.
  • the first coating does not contain the first polymer of the present application (the number of particles with the maximum length of the polymer particles between 10 ⁇ m and 30 ⁇ m is 0, such as Comparative Example 1 and Comparative Example 4), the normal temperature of the lithium ion battery Rate performance, rate performance at low temperature, and low temperature cycle performance are all poor; when the number of particles with a maximum length of the first polymer particle between 10 ⁇ m and 30 ⁇ m is too large or too small (for example, Comparative Examples 2, 3 and 5, 6), it is difficult to improve the normal temperature rate performance, low temperature rate performance and low temperature cycle performance of lithium ion batteries.
  • the coating areal density of the first coating usually also affects the performance of lithium-ion batteries. It can be seen from Examples 6 to 9 that as long as the coating areal density of the first coating is within the scope of the application, the battery can be obtained. Lithium-ion battery with excellent hardness, room temperature rate performance, low temperature rate performance and low temperature cycle performance.
  • the Dv50 of the first polymer usually also affects the performance of lithium-ion batteries. It can be seen from Examples 10 to 12 that as long as the Dv50 of the first polymer is within the scope of the application, the battery hardness, room temperature rate performance, Li-ion battery with excellent rate performance at low temperature and low temperature cycle performance.
  • the softening point of the first polymer usually also affects the performance of lithium-ion batteries. It can be seen from Examples 13 to 16 that as long as the softening point of the first polymer is within the scope of the application, the battery hardness and room temperature rate can be obtained. Li-ion battery with excellent performance, low temperature rate performance and low temperature cycling performance.
  • the composition and content of the first auxiliary binder usually also affect the performance of lithium-ion batteries. It can be seen from Examples 17 to 21 that as long as the composition and content of the first auxiliary binder are within the scope of the present application, it can be A lithium ion battery with excellent battery hardness, room temperature rate performance, low temperature rate performance and low temperature cycle performance is obtained.
  • the composition and content of the first polymer usually also affect the performance of lithium-ion batteries. It can be seen from Examples 22 to 27 that as long as the composition and content of the first polymer are within the scope of the present application, the battery hardness, Lithium-ion battery with excellent rate performance at room temperature, rate performance at low temperature and low temperature cycle performance.
  • composition and Dv50 of the inorganic particles in the heat-resistant layer usually also affect the performance of lithium-ion batteries.
  • a battery can be obtained. Lithium-ion battery with excellent hardness, room temperature rate performance, low temperature rate performance and low temperature cycle performance.
  • composition and content of the second polymer, the composition and content of the second auxiliary binder, the Dv50 of the second polymer, and the coating areal density of the second coating generally affect the performance of lithium-ion batteries, from Examples 34 to 43, it can be It can be seen that as long as the composition and content of the second polymer, the composition and content of the second auxiliary binder, the Dv50 of the second polymer, and the coating areal density of the second coating are within the scope of the present application, a battery can be obtained. Lithium-ion battery with excellent hardness, room temperature rate performance, low temperature rate performance and low temperature cycle performance.
  • Example 7 and Examples 44 and 45 it can be seen from Example 7 and Examples 44 and 45 that by providing the heat-resistant layer and the second coating layer in the separator, the battery hardness, room temperature rate performance, low temperature rate performance and low temperature rate performance of the lithium ion battery can be further improved cycle performance.

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Abstract

本申请提供了一种隔离膜及包含所述隔离膜的电化学装置和电子装置，包括基材和设置于基材至少一个表面上的第一涂层，其中，第一涂层包含第一聚合物，在第一涂层表面的任意250μm×200μm区域内，第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在10个至30个。本申请的隔离膜具有优异的界面粘结性能，提高了锂离子电池的结构稳定性，使锂离子电池具有更好的充放电性能，尤其是低温条件下的倍率性能和循环性能。

Description

一种隔离膜及包含所述隔离膜的电化学装置和电子装置 技术领域
本申请涉及锂离子电池技术领域，具体涉及一种隔离膜及包含所述隔离膜的电化学装置和电子装置。
背景技术
锂离子电池的结构中，隔离膜是关键的内层组件之一。隔离膜的性能决定了电池的界面结构、内阻等，直接影响电池的容量、循环以及安全性能等特性，性能优异的隔离膜对提高电池的综合性能具有重要的作用。隔离膜的主要作用是使电池的正、负极分隔开来，防止两极接触而短路，此外还具有能使电解质离子通过的功能。现有的锂离子电池隔离膜通常为涂层隔离膜，然而现有的涂层隔离膜往往无法同时满足高粘结性和高动力学性能的需求，有鉴于此，需要提供一种能够兼顾粘结性和动力学性能的涂层隔离膜。
并且，随着锂离子电池在消费终端等领域应用的迅速发展，人们对锂离子电池的充放电循环性能也有了越高的要求。尤其是在低温条件下，锂离子电池的实际充放电性能远小于设计值，制约了锂离子电池的进一步应用。
发明内容
本申请的目的在于提供一种隔离膜及包含所述隔离膜的电化学装置和电子装置，以提高锂离子电池的倍率性能和循环性能，尤其是在低温条件下的倍率性能和循环性能。具体技术方案如下：
需要说明的是，本申请的内容中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
本申请的第一方面提供了一种隔离膜，包括基材和设置于基材至少一个表面上的第一涂层，其中，第一涂层包含第一聚合物，在第一涂层表面的任意250μm×200μm区域内，第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在10个至30个，优选为20个至30个。
本申请的隔离膜采用SEM(扫描电子显微镜)在500倍的放大倍数下观察，在任意250μm×200μm区域(也即一个目镜所能观察到的区域)内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在10个至30个。不限于任何理论，通过控制第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在上述范围内，能够在第一涂层中呈现点 状离散分布，为电解液传输提供通道，能够进一步提升锂离子电池的性能，尤其是低温性能。
本申请的第一涂层设置在隔离膜基材的至少一个表面，例如，第一涂层可以设置在隔离膜基材的一个表面上，或者第一涂层可以设置在隔离膜基材的两个表面上。本申请的正极具体可以指正极极片，负极具体可以指负极极片。
在本申请的一种实施方案中，隔离膜的透气值P为500sec/100mL至10000sec/100mL，优选为1000sec/100mL至5000sec/100mL。当隔离膜的透气值P过高时(例如高于10000sec/100mL)，导致锂离子电池内阻增大，会影响电池的倍率放电性能，尤其是低温下的倍率放电性能；当隔离膜的透气值P过低时(例如低于500sec/100mL)，隔离膜的透气性能虽然较好，但是对应电芯(锂离子电池)的硬度较低，易出现软电芯。通过控制本申请隔离膜的透气值P在上述范围内，能够使锂离子电池具有优异的倍率性能，尤其是低温下的倍率性能，并使电芯的硬度得到较好的提高。
在本申请的一种实施方案中，隔离膜的第一涂层涂布面密度W1为0.4g/m 2至2g/m 2，优选的，第一涂层涂布面密度W1为0.4g/m 2至1g/m 2。不限于任何理论，当第一涂层涂布面密度W1过低时(例如低于0.4g/m 2)，会使界面间粘结力不足，涂层粘结性能下降；当第一涂层涂布面密度W1过高时(例如高于2g/m 2)，锂离子电池中的电极活性材料相对含量下降，影响锂离子电池的能量密度。通过控制本申请第一涂层涂布面密度W1在上述范围内，能够使隔离膜与电极极片之间具有优良的界面间粘结性能，对锂离子电池的能量密度影响较小。
在本申请的一种实施方案中，隔离膜的孔隙率K为30％至65％。不限于任何理论，当隔离膜的孔隙率K过低时(例如低于30％)，电解液难以浸润隔离膜，影响隔离膜的离子传输能力；当隔离膜的孔隙率K过高时(例如高于65％)，隔离膜变得疏松，强度下降，影响影响隔离膜的抗穿刺性能。通过控制本申请隔离膜的孔隙率K在上述范围内，能够使隔离膜具有优良的离子传输能力和强度。
在本申请的一种实施方案中，隔离膜还包括耐热层，耐热层可以设置在基材和第一涂层之间。耐热层包括无机粒子，无机粒子的Dv50为0.5μm至35μm，优选为5μm至35μm。通过在基材和第一涂层之间设置耐热层，能够进一步提高隔离膜的强度和耐热性能。无机粒子的粒径不宜过大或过小，当无机粒子的粒径过大时(例如大于35μm)，难以实现耐热层的薄涂布设计，影响锂离子电池的能量密度；当无机粒子的粒径过小时(例如小于0.5μm)， 导致无机粒子堆积孔隙减小，影响离子传输，从而影响锂离子电池的动力学性能。通过控制无机粒子的Dv50在上述范围内，能够使隔离膜具有较高的能量密度和优良的动力学性能。本申请对耐热层的厚度没有特别限制，例如可以为0.6μm至40μm，只要使得耐热层满足本申请要求即可。
本申请对耐热层中的无机粒子没有特别限制，只要能达到本申请目的即可，无机粒子包括勃姆石、氢氧化镁、氧化铝、二氧化钛、二氧化硅、二氧化锆、二氧化锡、氧化镁、氧化锌、硫酸钡、氮化硼或氮化铝中的至少一种。
在本申请的一种实施方案中，隔离膜的透气值P与第一涂层面密度W1满足如下关系：P/W1＝500至6500。不限于任何理论，当隔离膜的透气值P与第一涂层面密度W1的比值过低时(例如P/W1低于500)，表明隔离膜的透气值低、第一涂层涂布面密度小，导致隔离膜与极片的界面粘接差，影响锂离子电池的硬度，易导致软电芯；当隔离膜的透气值P与第一涂层面密度W1的比值过高时(例如P/W1高于6500)，表明隔离膜的透气值高、透气性能差、第一涂层涂布面密度大，导致锂离子电池内阻增大，影响电池的倍率性能，尤其是低温下的倍率性能。通过控制隔离膜的透气值P与第一涂层面密度W1的比值在上述范围内，能够使锂离子电池具有优异的倍率性能，尤其是低温下的倍率性能。
在本申请的一种实施方案中，隔离膜的孔隙率K与第一涂层面密度W1满足如下关系：K/W1＝0.15至1.4。不限于任何理论，当隔离膜的孔隙率K与第一涂层面密度W1的比值过低时(例如K/W1低于0.15)，表明隔离膜的孔隙率低、第一涂层涂布面密度大，电解液难以浸润隔离膜，影响隔离膜的离子传输能力；当隔离膜的孔隙率K与第一涂层面密度W1的比值过高时(例如K/W1低于1.4)，表明隔离膜的孔隙率高、第一涂层涂布面密度小，隔离膜变得疏松，强度下降，影响影响隔离膜的抗穿刺性能。通过控制隔离膜的孔隙率K与第一涂层面密度W1的比值在上述范围内，能够使隔离膜具有优良的离子传输能力和强度。
在本申请的一种实施方案中，第一涂层还包括第一辅助粘结剂，第一聚合物与第一辅助粘结剂质量比为2.5至18。不限于任何理论，当第一聚合物与第一辅助粘结剂质量比过低时(例如低于2.5)，第一聚合物的含量下降，使得颗粒状的第一聚合物带来的间隙减少，影响电解液在第一涂层界面间的传输，同时影响第一涂层与电极极片间的粘结力；当第一聚合物与第一辅助粘结剂质量比过高时(例如高于18)，第一涂层内聚力较低，第一聚合物的粘结性能会随第一涂层内聚力的降低而下降。通过控制第一聚合物与第一辅助粘结剂 质量比在上述范围内，能够使第一涂层与电极极片间具有优良的粘结力。
本申请对第一辅助粘结剂没有特别限制，只要满足本申请要求即可，例如可以包括丙烯酸乙酯、丙烯酸丁酯、甲基丙烯酸乙酯、苯乙烯、氯苯乙烯、氟苯乙烯、甲基苯乙烯、丙烯酸、甲基丙烯酸、马来酸、丙烯腈或丁二烯中的至少一种。
在本申请的一种实施方案中，隔离膜还包括第二涂层，第一涂层和第二涂层可以分别设置在隔离膜的两侧。第二涂层包括第二聚合物和第二辅助粘结剂，第二聚合物与第二辅助粘结剂质量比为5至20。不限于任何理论，当第二聚合物与第二辅助粘结剂质量比过低时(例如低于5)，第二聚合物的含量下降，影响第二涂层与电极极片间的粘结力；当第二聚合物与第二辅助粘结剂质量比过高时(例如高于20)，第二涂层内聚力较低，第二涂层粘结性能下降。通过控制第二聚合物与第二辅助粘结剂质量比在上述范围内，能够使第二涂层与电极极片间具有优良的粘结力。
本申请中，可以将隔离膜具有第一涂层的一面与正极极片接触，将隔离膜具有第二涂层的一面与负极极片接触，使隔离膜与正极极片和负极极片间均具有优良的粘结效果，且隔离膜与正极极片间具有更好的电解液浸润性，从而改善锂离子电池的低温性能。本申请的隔离膜具有锂离子透过性及电子阻隔性。
在本申请的一种实施方案中，第一涂层设置面对正极时的粘接强度4N/m至20N/m，表明第一涂层与正极极片之间具有优良的粘接性能。
在本申请的一种实施方案中，第二涂层设置面对负极时的粘接强度4N/m至20N/m，表明第二涂层与负极极片之间具有优良的粘接性能。
在本申请的一种实施方案中，基于第一涂层的总质量，第一聚合物的质量百分含量为85％至95％，第一辅助粘结剂的质量百分含量为5％至15％。通过控制第一聚合物和第一辅助粘结剂的含量在上述范围内，能够得到粘接性能优异的第一聚合物，使第一涂层与正极之间具有较高的粘结力，从而提高锂离子电池在低温下的性能。
在本申请的一种实施方案中，第一聚合物的软化点为90℃至150℃，优选为110℃至150℃。不限于任何理论，当第一聚合物的软化点过高时(例如高于150℃)，第一聚合物在加热时不易软化，形成的粘结面积较小，影响第一涂层与电极极片间的粘结力；当第一聚合物的软化点过低时(例如低于90℃)，第一聚合物易软化后堵塞涂层/隔离膜孔隙，影响锂离子电池的动力学性能。通过控制本申请第一聚合物的软化点在上述范围内，能够使第一聚合物具有优异的粘结性能，从而提高第一涂层与电极极片间的粘结力。术语“软化点” 表示物质软化的温度。第一聚合物的Dv50为3μm至16μm，不限于任何理论，当第一聚合物的Dv50过小时(例如小于3μm)，隔离膜与电极极片间的界面间距过小，传输电解质溶液的能力降低；当第一聚合物的Dv50过大时(例如大于16μm)，颗粒状的第一聚合物带来的间隙过大，也会影响隔离膜与电极极片间的粘结性能。通过控制本申请第一聚合物的Dv50在上述范围内，可以获得粘结性优良的第一聚合物。
在本申请的一种实施方案中，隔离膜的第二涂层涂布面密度W2为0.1g/m 2至1g/m 2。不限于任何理论，当第二涂层涂布面密度W2过低时(例如低于0.1g/m 2)，会使界面间粘结力不足，涂层粘结性能下降；当第二涂层涂布面密度W2过高时(例如高于1g/m 2)，易堵塞锂离子传输通道，影响锂离子电池的倍率性能。通过控制本申请第二涂层涂布面密度W2在上述范围内，既能够使隔离膜与电极极片之间具有优良的界面间粘结性能，对锂离子电池的倍率性能影响较小。
在本申请的一种实施方案中，基于第二涂层的总质量，第二聚合物的质量百分含量为88％至92.5％，第二辅助粘结剂的质量百分含量为7.5％至12％。通过控制第二聚合物和第二辅助粘结剂的含量在上述范围内，能够得到粘接性能优异的第二涂层，使第二涂层与负极之间具有较高的粘结力，从而提高锂离子电池在低温下的性能。
在本申请的一种实施方案中，第一聚合物包括偏氟乙烯、六氟丙烯、乙烯、丙烯、氯乙烯、氯丙烯、丙烯酸、丙烯酸酯、苯乙烯、丁二烯和丙烯腈的均聚物或共聚物中的至少一种。
本申请对第二聚合物没有特别限制，只要满足本申请要求即可，例如第二聚合物可以包括丙烯酸乙酯、丙烯酸丁酯、甲基丙烯酸乙酯、苯乙烯、氯苯乙烯、氟苯乙烯、甲基苯乙烯、丙烯酸、甲基丙烯酸、马来酸、丙烯腈或丁二烯中的至少一种。在本申请的一种实施方案中，第二聚合物的Dv50为0.2μm至8μm，通过控制第二聚合物的Dv50在上述范围内，能够获得粘结性优良的第二聚合物。本申请对第二辅助粘结剂没有特别限制，只要满足本申请要求即可，例如第二辅助粘结剂可以包括羧甲基纤维素钠或二甲基硅氧烷中的至少一种。
本申请的第一聚合物的制备方法没有特别限制，可以采用本领域技术人员的制备方法，例如可以采用如下制备方法：
对反应釜抽真空，抽氮气置换氧气后，向含有搅拌器的反应釜内加入去离子水、偏氟乙烯(VDF)、乳化剂全氟烷基羧酸盐、链转移剂异丙醇至反应釜压力为3.5MPa左右。然 后升温至50℃至70℃，搅拌器转速70r/min至100r/min，开始聚合反应，同时不断补加偏氟乙烯单体保持反应釜压力3.5MPa，直到反应器中乳液固含量达到25％至30％停止反应，回收未反应单体，放出聚合物乳液，经离心、洗涤、干燥后，得到第一聚合物。
本申请对引发剂没有特别限制，只要能引发单体聚合即可，例如可以为二异丙苯过氧化氢。本申请对单体、去离子水、引发剂、链转移剂的添加量没有特别限制，只要能保证加入的单体发生聚合反应即可，例如去离子水为单体质量的5倍至10倍，引发剂占单体质量的0.05％至0.5％，乳化剂占单体质量的0.1％至1％，链转移剂占单体质量的3％至7％。
本申请对第一辅助粘结剂、第二聚合物及第二辅助粘结剂的制备方法也没有特别限制，可以采用本领域技术人员常用的制备方法，根据所采用的单体种类不同进行选择，例如溶液法、浆液法、气相法等等。
本申请中的正极极片没有特别限制，只要能够实现本申请目的即可。例如，正极极片通常包含正极集流体和正极活性材料层。其中，正极集流体没有特别限制，可以为本领域的任何正极集流体，例如铝箔、铝合金箔或复合集流体等。正极活性材料层包括正极活性材料，正极活性材料没有特别限制，可以使用本领域的任何正极活性材料，例如，可以包括镍钴锰酸锂(811、622、523、111)、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂、锰酸锂、磷酸锰铁锂或钛酸锂中的至少一种。
本申请中的负极极片没有特别限制，只要能够实现本申请目的即可。例如，负极极片通常包含负极集流体和负极活性材料层。其中，负极集流体没有特别限制，可以使用本领域的任何负极集流体，例如铜箔、铝箔、铝合金箔以及复合集流体等。负极活性材料层包括负极活性材料，负极活性材料没有特别限制，可以使用本领域的任何负极活性材料。例如，可以包括人造石墨、天然石墨、中间相碳微球、软碳、硬碳、硅、硅碳、钛酸锂等中的至少一种。
本申请的隔离膜的基材包括但不限于，选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺或芳纶中的至少一种。举例来说，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯和超高分子量聚乙烯中的至少一种组分。尤其是聚乙烯和聚丙烯，它们对防止短路具有优良的作用，并可以通过关断效应改善锂离子电池的稳定性。
本申请的锂离子电池还包括电解质，电解质可以是凝胶电解质、固态电解质和电解液中的一种或多种，电解液包括锂盐和非水溶剂。在本申请一些实施方案中，锂盐选自LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、 LiSiF 6、LiBOB和二氟硼酸锂中的一种或多种。举例来说，锂盐可以选用LiPF 6，因为它可以给出高的离子导电率并改善循环特性。非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂或它们的组合。上述碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物或其组合。上述链状碳酸酯化合物的实例为碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸甲乙酯(MEC)及其组合。环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)及其组合。氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯、碳酸三氟甲基亚乙酯及其组合。上述羧酸酯化合物的实例为甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯、己内酯及其组合。上述醚化合物的实例为二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃、四氢呋喃及其组合。上述其它有机溶剂的实例为二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯、和磷酸酯及其组合。
本申请的第二方面提供了一种电化学装置，包括上述任一实施方案中的隔离膜，具有优良的低温倍率性能和低温循环性能。本申请的第三方面提供了一种电子装置，包含本申请上述实施方案中所述的电化学装置，具有优良的低温倍率性能和低温循环性能。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制。例如锂离子电池可以通过以下过程制造：将正极和负极经由隔离膜重叠，并根据需要将其卷绕、 折叠等操作后放入壳体内，将电解液注入壳体并封口，其中所用的隔离膜为本申请提供的上述隔离膜。此外，也可以根据需要将防过电流元件、导板等置于壳体中，从而防止锂离子电池内部的压力上升、过充放电。
本申请中，术语“透气值”指100ml空气通过隔离膜所需要的时间，透气值越大说明隔膜的透气性能越差，透气值越小说明隔膜的透气性能越好；术语“Dv50”表示颗粒累积分布为50％的粒径，即小于此粒径的颗粒体积含量占全部颗粒的50％。
本申请提供一种隔离膜及包含所述隔离膜的电化学装置和电子装置，包括基材和设置于基材至少一个表面上的第一涂层，其中，第一涂层包含第一聚合物，在第一涂层表面的任意250μm×200μm区域内，所述第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在10个至30个。本申请的隔离膜具有优异的界面粘结性能，提高了锂离子电池的结构稳定性，使锂离子电池具有更好的充放电性能，尤其是低温条件下的倍率性能和循环性能。
附图说明
为了更清楚地说明本申请和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例。
图1为本申请的第一种实施方案的隔离膜的结构示意图；
图2为本申请的第二种实施方案的隔离膜的结构示意图；
图3为本申请的第三种实施方案的隔离膜的结构示意图；
图4为本申请的第四种实施方案的隔离膜的结构示意图。
图中，1.基材，2.第一涂层，3.第二涂层，4.耐热层。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图和实施例，对本申请进一步详细说明。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。基于本申请中的实施例，本领域普通技术人员所获得的所有其他技术方案，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
在本申请的一种实施方案中，如图1所示，本申请的隔离膜包括基材1，以及设置于基材1一个表面上的第一涂层2。
在本申请的一种实施方案中，如图2所示，基材1的一个表面设置第一涂层2，另一个表面设置第二涂层3，其中，第一涂层2与基材1之间还设置有耐热层4。
在本申请的一种实施方案中，如图3所示，隔离膜包括基材1，以及分别设置于基材1的两个表面上的第一涂层2和第二涂层3。
在本申请的一种实施方案中，如图4所示，隔离膜包括基材1，以及分别设置于基材1两个表面上的第一涂层2。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
第一涂层表面250μm×200μm面积内第一聚合物颗粒数量测试：
将涂有第一涂层的隔离膜裁切为10mm×10mm样品，然后将样品放置在SEM下以500倍放大倍率观察，并在视野中选取任意5个250μm×200μm区域(也即一个目镜下所能观察到的区域)，记录所选取区域中第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量，然后取平均值，即为第一涂层单位面积区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量。
隔离膜透气值测试：
将放电后的待测试锂离子电池进行拆解，然后取出隔离膜，将隔离膜浸泡在N-甲基吡咯烷酮(NMP)中30min，然后在通风橱中25℃干燥4小时，取出干燥后的隔离膜，在温度为25℃和湿度小于80％的环境下，将测试样品制成4cm×4cm大小，使用透气度测试仪(Air-permeability-tester)，通过Gurley test(100mL)方法测量直接得到透气值，单位为秒(sec)，即代表100mL空气通过4cm×4cm面积隔离膜所需的时间。
隔离膜孔隙率测试：
将隔离膜样品在85℃真空干燥箱中烘干2h，取出置于干燥器中冷却后再测试，将隔离膜用A4纸包裹平整，平铺在刀模上，用冲压机冲压，备好样品做测试用。先使用万分尺测量样品的厚度，根据样品表面积和厚度来计算样品的表观体积V1，再使用真密度仪(型号AccuPycⅡ)测试样品的真实体积V2，可以得出孔隙率＝(V1-V2)/V1×100％。
无机粒子、第一聚合物、第二聚合物的Dv50测试：
使用激光粒度仪分别测试无机粒子、第一聚合物、第二聚合物的Dv50。
隔离膜与电极极片间粘结力测试：
采用国家标准GB/T 2790-1995，即采用180°剥离测试标准测试隔离膜与正极极片或负极极片之间的粘结力，将隔离膜和正极极片或负极极片裁切成54.2mm×72.5mm样品，将隔离膜与正极极片或负极极片复合，使用热压机热压，热压条件为：温度85℃，压力1Mpa，热压时间85s(秒)，将复合好的样品裁切成15mm×54.2mm小条，按照180°剥离测试标准测试隔离膜与正极极片或负极极片之间的粘结力。
第一聚合物的软化点测试：
采用通用型差示扫描量热仪(DSC)法：分别取5mg各实施例和对比例制备的第一聚合物样品，以5℃/min的升温速率升温至150℃，采集DSC曲线，由所得DSC曲线确定第一聚合物的软化点，也即软化温度。
锂离子电池硬度测试：
采用三点弯曲法测试电芯硬度：在25℃下进行操作，将电芯完全放电至3.0V，极耳做绝缘保护。将万能试验机(Instron-3365)的硬度测试夹具下支撑杆的间距调整到电芯宽度的2/3，电芯平放在下夹具上，宽度方向与支撑杆垂直。调整夹具的上压头与宽度方向垂直，并处于电芯的正中央位置，以5mm/min的速度往下压，上压头刚开始接触电芯的记录电芯形变位移，当位移到达1mm时，此时对应抗形变的力即为电芯的硬度。下支撑杆为圆弧形，直径10mm；上压头为圆弧形，直径10mm。
锂离子电池放电倍率测试：
2C放电倍率测试：在25℃下，将化成后的锂离子电池以0.2C倍率恒流充电至4.45V，再恒压充电至电流小于等于0.05C，之后静置30分钟，再以0.2C倍率恒流放电至3.0V，测试得到锂离子电池0.2C倍率放电容量；
在25℃下，将锂离子电池以0.2C倍率恒流充电至4.45V，再恒压充电至电流小于等于0.05C，之后静置30分钟，再以2C倍率恒流放电至3.0V，测试得到锂离子电池2C倍率放电容量。
锂离子二次电池2C倍率放电容量保持率(％)＝2C倍率放电容量/0.2C倍率放电容量 ×100％。
-20℃ 0.2C放电倍率测试：在25℃下，将化成后的锂离子电池以0.2C倍率恒流充电至4.45V，再恒压充电至电流小于等于0.05C，之后静置30分钟，再以0.2C倍率恒流放电至3.0V，测试得到锂离子电池25℃0.2C倍率放电容量；
在25℃下，将锂离子电池以0.2C倍率恒流充电至4.45V，再恒压充电至电流小于等于0.05C；之后将电芯放置在-20℃环境中，静置60分钟，再以0.2C倍率恒流放电至3.0V，测试得到锂离子电池-20℃0.2C倍率放电容量。
锂离子二次电池-20℃0.2C倍率放电容量保持率(％)＝-20℃0.2C倍率放电容量/25℃0.2C倍率放电容量×100％。
锂离子电池循环性能测试：
在12℃的环境中，进行第一次充电和放电，在2C的充电电流下进行恒流和恒压充电，直到上限电压为4.45V，然后在1C的放电电流下进行恒流放电，直到最终电压为3.0V，记录首次循环的放电容量，之后重复上述步骤进行500次的充电和放电循环，记录第500次循环的放电容量。循环容量保持率＝(第500次循环的放电容量/首次循环的放电容量)×100％。
实施例1
<1-1.第一聚合物的制备>
对反应釜抽真空，抽氮气置换氧气后，向含有搅拌器的反应釜内加入去离子水、偏氟乙烯(VDF)、引发剂二异丙苯过氧化氢、乳化剂全氟烷基羧酸盐、链转移剂异丙醇至反应釜压力为3.5MPa，其中去离子水为偏氟乙烯单体质量的7倍，引发剂占偏氟乙烯单体质量的0.2％，乳化剂占偏氟乙烯单体质量的0.5％，链转移剂占偏氟乙烯单体质量的5％。然后升温至60℃，搅拌器转速80r/min，开始聚合反应，同时不断补加偏氟乙烯单体保持反应釜压力3.5MPa，直到反应器中乳液固含量达到25％停止反应，回收未反应单体，放出聚合物乳液，经离心、洗涤、干燥后，得到第一聚合物。该第一聚合物的软化点为125℃，Dv50为12μm。
<1-2.隔离膜的制备>
<1-2-1.第一涂层的制备>
将制备好的第一聚合物和第一辅助粘结剂(由质量分数为80％的苯乙烯、10％的丙烯 酸异丁酯、10％的丙烯腈聚合形成的共聚物，Dv50为0.2μm)按照质量比90∶10加入搅拌器中，搅拌混合均匀，再加入去离子水进行搅拌，调整浆料粘度为100mPa·s，固含量为12％，得到浆料A；将浆料A均匀地涂布在厚度为5μm的PE隔离膜基材的一个面上，第一涂层的涂布面密度为1g/m 2，在烘箱中完成干燥，形成如图1所示结构的隔离膜。
将所制得的隔离膜通过SEM在500倍放大倍率下观察，在第一涂层表面的任意250μm×200μm区域内(单位面积区域内)，第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在10个(表1中简称颗粒数量)。
<1-3.正极极片的制备>
将正极活性材料钴酸锂、乙炔黑、聚偏氟乙烯(PVDF)按质量比94∶3∶3混合，然后加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂布在厚度为12μm的铝箔的一个表面上，90℃条件下烘干，冷压后得到正极活性材料层厚度为100μm的正极极片，然后在该正极极片的另一个表面上重复以上步骤，得到双面涂布有正极活性材料层的正极极片。将正极极片裁切成74mm×867mm的规格并焊接极耳后待用。
<1-4.负极极片的制备>
将负极活性材料人造石墨、乙炔黑、丁苯橡胶及羧甲基纤维素钠按质量比96∶1∶1.5∶1.5混合，然后加入去离子水作为溶剂，调配成固含量为70％的浆料，并搅拌均匀。将浆料均匀涂布在厚度为8μm的铜箔的一个表面上，110℃条件下烘干，冷压后得到负极活性材料层厚度为150μm的单面涂布负极活性材料层的负极极片，然后在该负极极片的另一个表面上重复以上涂布步骤，得到双面涂布有负极活性材料层的负极极片。将负极极片裁切成74mm×867mm的规格并焊接极耳后待用。
<1-5.电解液的制备>
在含水量小于10ppm的环境下，将非水有机溶剂碳酸乙烯酯(EC)、碳酸二乙酯(DEC)、碳酸亚丙酯(PC)、丙酸丙酯(PP)、碳酸亚乙烯酯(VC)按照质量比20∶30∶20∶28∶2混合，然后向非水有机溶剂中加入六氟磷酸锂(LiPF 6)溶解并混合均匀，得到电解液，其中，LiPF 6与非水有机溶剂的质量比为8∶92。
<1-6.锂离子电池的制备>
将上述制备的正极极片、隔离膜、负极极片按顺序叠好，将隔离膜具有第一涂层的一面与正极极片接触，卷绕得到电极组件。将电极组件装入铝塑膜包装袋中，并在80℃下脱 去水分，注入配好的电解液，经过真空封装、静置、化成、整形等工序得到锂离子电池。
实施例2
除了在<隔离膜的制备>中，调高浆料A的固含量，如表1所示使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在15个以外，其余与实施例1相同。
实施例3
除了在<隔离膜的制备>中，调高浆料A的固含量，如表1所示使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在20个以外，其余与实施例1相同。
实施例4
除了在<隔离膜的制备>中，调高浆料A的固含量，如表1所示使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在26个以外，其余与实施例1相同。
实施例5
除了在<隔离膜的制备>中，调高浆料A的固含量，如表1所示使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在30个以外，其余与实施例1相同。
实施例6
除了在<隔离膜的制备>中增加耐热层及第二涂层、如表2-2所示调整第一涂层的涂布面密度为0.4g/m 2、<锂离子电池的制备>与实施例1不同以外，其余与实施例1相同。
<1-6.隔离膜的制备>
<1-6-1.耐热层的制备>
将Dv50为2μm的无机粒子勃姆石与聚丙烯酸酯依照质量比90∶10混合并将其均匀分散到去离子水中以形成固含量为50％的耐热层浆料，随后采用微凹版涂布法将所得耐热层浆料均匀涂布到隔离膜基材的其中一面上，得到相应厚度的耐热层，在烘箱中完成干燥。然后按照实施例1的<第一涂层的制备>，在耐热层表面制备第一涂层。
<1-6-2.第二涂层的制备>
将第二聚合物(由质量分数为80％的苯乙烯、10％的丙烯酸异丁酯、10％的丙烯腈聚合形成的共聚物，Dv50为0.2μm)和第二辅助粘结剂(5.5％羧甲基纤维素钠和94.5％二甲 基硅氧烷形成的混合物)按照质量比91∶9加入搅拌器中，搅拌混合均匀，再加入去离子水进行搅拌，调整浆料粘度为100mPa·s，固含量为12％，得到浆料B；将浆料B均匀地涂布在隔离膜基材的另一面(即隔离膜未设置第一涂层的一面)，第二涂层的涂布面密度为0.2g/m 2，在烘箱中完成干燥，形成如图2所示结构的隔离膜。
将所制得的隔离膜通过SEM在500倍放大倍率下观察，在第一涂层表面的任意250μm×200μm区域内(单位面积区域内)，第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在25个(表1和表2-2中简称颗粒数量)。
<锂离子电池的制备>
将上述制备的正极极片、隔离膜、负极极片按顺序叠好，将隔离膜具有第一涂层的一面与正极极片接触，将隔离膜具有第二涂层的一面与负极极片接触，并卷绕得到电极组件。将电极组件装入铝塑膜包装袋中，并在80℃下脱去水分，注入配好的电解液，经过真空封装、静置、化成、整形等工序得到锂离子电池。
实施例7、实施例8、实施例9，除了在<隔离膜的制备>中，如表2-2所示调整第一涂层的涂布面密度以外，其余与实施例6相同。
实施例10、实施例11、实施例12，除了在<第一聚合物的制备>中，采用与实施例1中的(1-1)第一聚合物的制备类似的方法制备第一聚合物，如表2-2所示调整第一聚合物的Dv50以外，其余与实施例7相同。
实施例13、实施例14、实施例15、实施例16，除了在<第一聚合物的制备>中，采用与实施例1中的(1-1)第一聚合物的制备类似的方法制备第一聚合物，如表2-2所示调整第一聚合物的软化点以外，其余与实施例7相同。
实施例17、实施例18、实施例19、实施例20、实施例21，除了在<第一涂层的制备>中，如表2-1所示调整第一辅助粘结剂成分和含量以外，其余与实施例7相同。
实施例22、实施例23、实施例24、实施例25、实施例26、实施例27，采用与实施例1中的(1-1)第一聚合物的制备类似的方法制备第一聚合物，如表2-1所示调整第一聚合物成分和含量以外，其余与实施例7相同。
实施例28、实施例29、实施例30、实施例31、实施例32、实施例33，除了在<耐热层的制备>中，如表2-2所示调整无机粒子的成分和Dv50以外，其余与实施例7相同。
实施例34、实施例35，除了在<第二涂层的制备>中，如表2-1所示调整第二聚合物和第二辅助粘结剂的成分和含量以外，其余与实施例7相同。
实施例36、实施例37、实施例38、实施例39、实施例40，除了在<第二涂层的制备>中，如表2-2所示调整第二聚合物的Dv50以外，其余与实施例7相同。
实施例41、实施例42、实施例43，除了在<第二涂层的制备>中，如表2-2所示调整第二涂层的涂布面密度以外，其余与实施例7相同。
实施例44除了在<第一涂层的制备>中，隔离膜表面未设置第二涂层以外，其余与实施例7相同。
实施例45除了在<第一涂层的制备>中，第一涂层和隔离膜基材之间未设置耐热层以外，其余与实施例7相同。
实施例46
除了在<隔离膜的制备>中，调低浆料A的固含量，如表2-2所示使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在10个以外，其余与实施例7相同。
实施例47
除了在<隔离膜的制备>中，调高浆料A的固含量，如表2-2所示使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在30个以外，其余与实施例7相同。
对比例1
除了在<隔离膜的制备>中，采用与实施例1中的(1-1)第一聚合物的制备类似的方法制备第一聚合物，第一聚合物为质量分数80％苯乙烯、10％丙烯酸异丁酯、10％丙烯腈聚合形成的共聚物，第一辅助粘结剂为质量分数5.5％羧甲基纤维素钠和94.5％二甲基硅氧烷组成的混合物，第一聚合物与第二聚合物的质量比为91∶9，使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在0个以外，其余与实施例1相同。
对比例2
除了在<隔离膜的制备>中，调高浆料A的固含量，使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在34个以外，其余与实施例1相同。
对比例3
除了在<隔离膜的制备>中，调低浆料A的固含量，使第一涂层表面任意250μm×200μm 区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在6个以外，其余与实施例1相同。
对比例4
除了在<隔离膜的制备>中，采用与实施例1中的(1-1)第一聚合物的制备类似的方法制备第一聚合物，第一聚合物为质量分数80％苯乙烯、10％丙烯酸异丁酯、10％丙烯腈聚合形成的共聚物，第一辅助粘结剂为质量分数5.5％羧甲基纤维素钠和94.5％二甲基硅氧烷组成的混合物，第一聚合物与第二聚合物的质量比为91∶9，如表2-2所示使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在0个以外，其余与实施例7相同。
对比例5
除了在<隔离膜的制备>中，通过调高浆料A的固含量，使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量如表2-2所示在34个以外，其余与实施例7相同。
对比例6
除了在<隔离膜的制备>中，通过调高浆料A的固含量，使第一涂层表面任意250μm×200μm区域内第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量如表2-2所示在6个以外，其余与实施例7相同。
各实施例和对比例的制备参数及测试结果如下表1、表2-1和表2-2所示。
表1
Figure PCTCN2021084667-appb-000001
表2-1
Figure PCTCN2021084667-appb-000002
Figure PCTCN2021084667-appb-000003
Figure PCTCN2021084667-appb-000004
表2-2
Figure PCTCN2021084667-appb-000005
Figure PCTCN2021084667-appb-000006
Figure PCTCN2021084667-appb-000007
从实施例1至5和对比例1至3、以及实施例6至47和对比例4至6可以看出，通过在第一涂层中将第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量控制在本申请范围内，能够显著提高锂离子电池的常温倍率性能、低温下的倍率性能以及低温循环性能，对锂离子电池的硬度影响不大。当第一涂层中不含本申请的第一聚合物时(聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量为0个，例如对比例1和对比例4)，锂离子电池的常温倍率性能、低温下的倍率性能以及低温循环性能均较差；当第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量过多时或过少时(例如对比例2、3和对比例5、6)，难以改善锂离子电池的常温倍率性能、低温下的倍率性能以及低温循环性能。
第一涂层的涂布面密度通常也会影响锂离子电池的性能，从实施例6至9可以看出，只要使得第一涂层的涂布面密度在本申请范围内，就能够得到电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能优良的锂离子电池。
第一聚合物的Dv50通常也会影响锂离子电池的性能，从实施例10至12可以看出，只要使得第一聚合物的Dv50在本申请范围内，就能够得到电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能优良的锂离子电池。
第一聚合物的软化点通常也会影响锂离子电池的性能，从实施例13至16可以看出，只要使得第一聚合物的软化点在本申请范围内，就能够得到电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能优良的锂离子电池。
第一辅助粘结剂的成分和含量通常也会影响锂离子电池的性能，从实施例17至21可以看出，只要使得第一辅助粘结剂的成分和含量在本申请范围内，就能够得到电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能优良的锂离子电池。
第一聚合物的成分和含量通常也会影响锂离子电池的性能，从实施例22至27可以看出，只要使得第一聚合物的成分和含量在本申请范围内，就能够得到电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能优良的锂离子电池。
耐热层无机粒子的成分和Dv50通常也会影响锂离子电池的性能，从实施例28至33可以看出，只要使得耐热层无机粒子的成分和Dv50在本申请范围内，就能够得到电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能优良的锂离子电池。
第二聚合物的成分和含量、第二辅助粘结剂成分和含量、第二聚合物的Dv50、第二涂层的涂布面密度通常影响锂离子电池的性能，从实施例34至43可以看出，只要使得第二聚合物的成分和含量、第二辅助粘结剂成分和含量、第二聚合物的Dv50、第二涂层的涂布 面密度在本申请范围内，就能够得到电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能优良的锂离子电池。
从实施例7和实施例44、45可以看出，通过在隔离膜中设置耐热层和第二涂层，能够进一步提高锂离子电池的电池硬度、常温倍率性能、低温下的倍率性能以及低温循环性能。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (21)

  1. 一种隔离膜，包括基材和设置于所述基材至少一个表面上的第一涂层，
    其中，所述第一涂层包含第一聚合物，在所述第一涂层表面的任意250μm×200μm区域内，所述第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在10个至30个。
  2. 根据权利要求1所述的隔离膜，其中，所述隔离膜的透气值P为500sec/100mL至10000sec/100mL。
  3. 根据权利要求1所述的隔离膜，其中，所述隔离膜的第一涂层涂布面密度W1为0.4g/m 2至2g/m 2。
  4. 根据权利要求1所述的隔离膜，其中，所述隔离膜的孔隙率K为30％至65％。
  5. 根据权利要求1所述的隔离膜，其中，所述隔离膜还包括耐热层，所述耐热层设置在所述基材和所述第一涂层之间，所述耐热层包括无机粒子，所述无机粒子粒径Dv50为0.5μm至35μm。
  6. 根据权利要求5所述的隔离膜，其中，所述无机粒子包括勃姆石、氢氧化镁、氧化铝、二氧化钛、二氧化硅、二氧化锆、二氧化锡、氧化镁、氧化锌、硫酸钡、氮化硼或氮化铝中的至少一种。
  7. 根据权利要求1所述的隔离膜，其中，所述隔离膜的透气值P与所述第一涂层面密度W1满足如下关系：P/W1＝500至6500。
  8. 根据权利要求1所述的隔离膜，其中，所述隔离膜的孔隙率K与所述第一涂层面密度W1满足如下关系：K/W1＝0.15至1.4。
  9. 根据权利要求1所述的隔离膜，其中，所述第一涂层还包括第一辅助粘结剂，所述第一辅助粘结剂包括丙烯酸乙酯、丙烯酸丁酯、甲基丙烯酸乙酯、苯乙烯、氯苯乙烯、氟苯乙烯、甲基苯乙烯、丙烯酸、甲基丙烯酸、马来酸、丙烯腈和丁二烯的均聚物或共聚物中的至少一种，第一聚合物与第一辅助粘结剂质量比为2.5至18。
  10. 根据权利要求1所述的隔离膜，其中，所述隔离膜还包括第二涂层，所述第一涂层和所述第二涂层分别设置在隔离膜的两侧，所述第二涂层包括第二聚合物和第二辅助粘结剂，第二聚合物与第二辅助粘结剂质量比为5至20。
  11. 根据权利要求9所述的隔离膜，其中，所述第一涂层设置面对正极时的粘接强度4N/m至20N/m。
  12. 根据权利要求10所述的隔离膜，其中，所述第二涂层设置面对负极时的粘接强度 4N/m至20N/m。
  13. 根据权利要求9所述的隔离膜，其中，基于所述第一涂层的总质量，所述第一聚合物的质量百分含量为85％至95％，所述第一辅助粘结剂的质量百分含量为5％至15％。
  14. 根据权利要求1所述的隔离膜，其中，所述第一聚合物的软化点为90℃至150℃，所述第一聚合物的Dv50为3μm至16μm。
  15. 根据权利要求1所述的隔离膜，其中，所述隔离膜的第二涂层涂布面密度W2为0.1g/m 2至1g/m 2。
  16. 根据权利要求10所述的隔离膜，其中，基于所述第二涂层的总质量，所述第二聚合物的质量百分含量为88％至92.5％，所述第二辅助粘结剂的质量百分含量为7.5％至12％。
  17. 根据权利要求1所述的隔离膜，其中，所述第一聚合物包括偏氟乙烯、偏氟乙烯、六氟丙烯、乙烯、丙烯、氯乙烯、氯丙烯、丙烯酸、丙烯酸酯、苯乙烯、丁二烯和丙烯腈的均聚物或共聚物中的至少一种。
  18. 根据权利要求10所述的隔离膜，其中，所述第二聚合物包括丙烯酸乙酯、丙烯酸丁酯、甲基丙烯酸乙酯、苯乙烯、氯苯乙烯、氟苯乙烯、甲基苯乙烯、丙烯酸、甲基丙烯酸、马来酸、丙烯腈和丁二烯的均聚物或共聚物中的至少一种，所述第二聚合物的Dv50为0.2μm至8μm；所述第二辅助粘结剂包括羧甲基纤维素钠或二甲基硅氧烷中的至少一种。
  19. 根据权利要求1所述的隔离膜，其中，所述隔离膜满足以下特征中的至少一种：
    a)在所述第一涂层表面的任意250μm×200μm区域内，所述第一聚合物颗粒最大长度处于10μm至30μm之间的颗粒数量在20个至30个；
    b)所述隔离膜的第一涂层涂布面密度W1为0.4g/m 2至1g/m 2；
    c)所述隔离膜的透气值P为1000sec/100mL至5000sec/100mL；
    d)所述隔离膜还包括耐热层，所述耐热层设置在所述基材和所述第一涂层之间，所述耐热层包括无机粒子，所述无机粒子粒径Dv50为5μm至35μm。
  20. 一种电化学装置，包括权利要求1-19中任一项所述的隔离膜。
  21. 一种电子装置，包含权利要求20所述的电化学装置。
PCT/CN2021/084667 2021-03-31 2021-03-31 一种隔离膜及包含所述隔离膜的电化学装置和电子装置 Ceased WO2022205165A1 (zh)

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