WO2023179333A1 - 隔离膜及其制备方法、电池和用电装置 - Google Patents

隔离膜及其制备方法、电池和用电装置 Download PDF

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Publication number
WO2023179333A1
WO2023179333A1 PCT/CN2023/079397 CN2023079397W WO2023179333A1 WO 2023179333 A1 WO2023179333 A1 WO 2023179333A1 CN 2023079397 W CN2023079397 W CN 2023079397W WO 2023179333 A1 WO2023179333 A1 WO 2023179333A1
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WIPO (PCT)
Prior art keywords
particles
isolation film
pressure
methacrylate
film according
Prior art date
Application number
PCT/CN2023/079397
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English (en)
French (fr)
Inventor
程晓楠
洪海艺
马艳云
杨建瑞
郑义
孙成栋
Original Assignee
宁德时代新能源科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from PCT/CN2022/083171 external-priority patent/WO2023178690A1/zh
Priority claimed from PCT/CN2022/144349 external-priority patent/WO2024138743A1/zh
Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to EP23773584.0A priority Critical patent/EP4318776A1/en
Priority to JP2023570444A priority patent/JP2024517980A/ja
Priority to CN202380011330.8A priority patent/CN117397109A/zh
Priority to KR1020237038616A priority patent/KR20230167125A/ko
Publication of WO2023179333A1 publication Critical patent/WO2023179333A1/zh
Priority to US18/657,806 priority patent/US20240313352A1/en

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Classifications

    • 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
    • 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
    • H01M50/42—Acrylic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—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
    • H01M50/489—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
    • 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
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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 belongs to the technical field of secondary batteries, and specifically relates to an isolation film and its preparation method, batteries and electrical devices.
  • the pole pieces and the isolation film will inevitably be misaligned during the transfer process. This may cause the pole pieces to come into contact with each other and cause the dry cell to be scrapped, or the pole pieces to break after being fully charged. Wrinkles seriously affect the dynamic performance and reduce the safety performance of the battery core. Therefore, an adhesive coating is currently applied to the isolation membrane, and during the first composite process of the pole piece of the electrochemical device and the isolation membrane, pre-pressure is usually carried out under appropriate pressure to ensure the polarity of the electrochemical device. The plate and the isolation film are bonded to a certain extent before entering the next process. However, due to the requirements of production efficiency, the pressure and action time at this time cannot satisfy the appropriate bonding between the electrode plate and the isolation film of the electrochemical device.
  • this application provides an isolation film, which is designed to achieve appropriate bonding between the pole piece of the electrochemical device and the isolation film under different pressures.
  • a first aspect of the present application provides an isolation film, which includes: a substrate and a pressure-sensitive coating, the pressure-sensitive coating is formed on at least part of the surface of the substrate, and the pressure-sensitive coating
  • the coating includes composite particles and a first plasticizer, the composite particles form protrusions on the surface of the pressure-sensitive coating, the composite particles include polyacrylate particles and inorganic particles, at least two of the polyacrylate particles With the inorganic particles in between, the absolute value of the difference between the solubility parameter of the first plasticizer and the solubility parameter of the composite particles is 0.3MPa 1/2 -4MPa 1/2 .
  • the isolation film of this application has good pressure-sensitive properties and compression modulus, and its adhesive force is below 0.1N/m under the action of ⁇ 1MPa. Therefore, It can avoid the adhesion between the layers of the isolation film during the winding and storage process. It can have obvious adhesion with the pole piece under the pressure of ⁇ 2MPa. Therefore, when using this isolation film to prepare the battery core, Under normal temperature conditions and appropriate pressure, the pole piece and the isolation film can be closely attached to improve the dynamic performance of the battery core.
  • the first plasticizer includes an ester compound, and the solubility parameter of the ester compound is 12MPa 1/2 -30MPa 1/2 . Thereby, it is possible to reduce the dissolution of the composite particles while improving the pressure-sensitive properties of the pressure-sensitive coating.
  • the pressure-sensitive coating further includes an emulsifier, and the emulsifier includes at least one of an anionic emulsifier and a nonionic emulsifier. This facilitates the uniform distribution of the first plasticizer in the composite particles, further improving the production efficiency and pressure-sensitive properties of the isolation film.
  • the pressure-sensitive coating includes 80-96 parts by weight of composite particles, 5-30 parts by weight of ester compounds, and 0.1-0.5 parts by weight of emulsifier.
  • the isolation film has good pressure-sensitive characteristics, thereby improving the dynamic performance of the battery core.
  • the Dv50 of the composite particles is ⁇ 2.5 ⁇ m, preferably 2.5 ⁇ m-10 ⁇ m, more preferably 3 ⁇ m-8 ⁇ m. This facilitates the formation of protruding structures on the surface of the pressure-sensitive coating, thereby improving the dynamic performance of the battery core.
  • the composite particles include a first agglomerate, and the first agglomerate includes at least two of the inorganic particles.
  • the composite particles include inorganic particles in the form of primary particles.
  • the Dv50 of the inorganic particles with primary particle morphology is 0.01 ⁇ m-1 ⁇ m, preferably 0.5 ⁇ m-1 ⁇ m. This ensures that the composite particles will not fuse and block the isolation membrane ions during the production process. transportation channel.
  • the composite particles include a second agglomerate, and the second agglomerate includes at least two of the polyacrylate particles.
  • the Dv50 of the second agglomerate is 0.3 ⁇ m-5 ⁇ m, preferably 1 ⁇ m-2 ⁇ m.
  • the polyacrylate particles include polyacrylate particles in the form of primary particles and/or polyacrylate particles in the form of secondary particles.
  • the Dv50 of the primary particle morphology polyacrylate particles is 50 nm-400 nm, preferably 100 nm-200 nm. This can improve the overall ion conductivity of the isolation film pressure-sensitive coating, reduce the isolation film resistance, and improve the cell dynamic performance.
  • the Dv50 of the polyacrylate particles with secondary particle morphology is 2 ⁇ m-15 ⁇ m, preferably 5 ⁇ m-8 ⁇ m. This can provide a buffer space for stress relief between the electrode pieces and prevent the corners of the wound cell from breaking due to stress accumulation.
  • the content of the inorganic particles in the composite particles is 1wt%-50wt%, optionally 1wt%-40wt%, more optionally 2wt%-15wt%, most preferably 5wt%-50wt% 15wt%.
  • the double-sided height of the protrusion is 15 ⁇ m-60 ⁇ m.
  • the convex surface has the first agglomerate. As a result, the dynamic performance of the battery can be improved.
  • the glass transition temperature of the polyacrylate particles is 20°C-80°C, preferably 25°C-65°C.
  • the pressure-sensitive coating further includes 4-20 parts by weight of a pressure-sensitive adhesive polymer, and the pressure-sensitive adhesive polymer includes an adhesive polymer and a second Plasticizer.
  • the average particle size of the adhesive polymer is 0.5 ⁇ m-3.0 ⁇ m, optionally 0.8 ⁇ m-2.0 ⁇ m. This facilitates the uniform distribution of the pressure-sensitive adhesive polymer among the composite particles and improves the pressure-sensitive properties of the isolation film.
  • the DSC melting point of the pressure-sensitive adhesive polymer is -50°C-100°C, optionally -45°C-60°C. Therefore, when the DSC melting point of the pressure-sensitive adhesive polymer is within the above range, the bonding force at room temperature can be ensured, and the bonding force of the isolation film caused by excessive bonding force at 1MPa can be avoided; at the same time, Avoid weak bonding between the isolation film and the pole piece due to too small adhesive force at room temperature of 2MPa, which is not conducive to cell shaping.
  • the mass ratio of the adhesive polymer to the second plasticizer is (4-19):1, optionally (4-11):1. Therefore, the relative content of the second plasticizer included in the pressure-sensitive adhesive polymer is within the above range, which can ensure that the pole piece and the isolation film obtain a large adhesive force under a certain pressure, and will not This results in an increase in the resistance of the separator film and a decrease in the cycle performance of the battery.
  • the pressure-sensitive adhesive polymer is a core-shell structure, and both the inner core and the outer shell of the core-shell structure include an adhesive polymer and a second plasticizer, wherein in the inner core
  • the mass ratio of the adhesive polymer and the second plasticizer in the structure is (2-5):1, optionally (3-4):1, and the adhesive polymer and the second plasticizer in the shell structure are The mass ratio of the second plasticizer is (6-10):1, optionally (7-9):1.
  • the adhesive polymer includes at least one of the following first monomers, at least one of the second monomers, at least one of the third monomers and a reactive type A copolymer formed from at least one reactive monomer in the dispersant:
  • First monomer including acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, hydroxymethylacrylamide, acrylamide, styrene, and acrylonitrile;
  • Second monomer including C4-C22 alkyl acrylate, isobutyl acrylate, isooctyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate (isooctyl), cyclohexyl acrylate, ethyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, methacrylate Cyclohexyl acrylate, benzyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, ethylene urea ethyl methacrylate, dicyclopentene ethoxy methacrylate, methacrylate Tetrahydrofuryl acrylate, trifluoroethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, ethylene
  • Third monomer including 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid Diethylaminoethyl ester, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, 3-methacryloyloxypropyltrimethoxysilane, N-hydroxymethyl Acrylamide, N-butoxymethyl (meth)acrylamide, diacetone acrylamide, ethyl methacrylate acetoacetate, divinylbenzene, epoxy resin with an epoxy value of 0.35-0.50, divinylbenzene;
  • Reactive dispersants including polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol, and polyvinyl alcohol.
  • the adhesive polymer has appropriate swelling and adhesion, ensure that the pressure-sensitive adhesive polymer has appropriate swelling, pressure sensitivity and adhesive properties, and at the same time have an appropriate elastic modulus, ensuring that The shaping effect, dynamic performance and safety performance of the battery core.
  • the second plasticizer includes glycerol C4-C10 alkyl diether, glycerol C4-C10 alkyl monoether, glycerol C4-C10 carboxylic acid monoester, glycerol C4-C10 carboxylic acid diether At least one of ester, propylene glycol C4-C10 alkyl monoether and glycerol.
  • the pressure-sensitive coating further includes organic particles, and the organic particles include polytetrafluoroethylene particles, polychlorotrifluoroethylene particles, polyvinyl fluoride particles, polyvinylidene fluoride particles, polyvinylidene fluoride particles, Ethylene particles, polypropylene particles, polyacrylonitrile particles, polyethylene oxide particles, copolymer particles of fluorine-containing alkenyl monomer units and vinyl monomer units, fluorine-containing alkenyl monomer units and acrylic monomer units copolymer particles, copolymer particles of fluorine-containing alkenyl monomer units and acrylate monomer units, and at least one of the modified compound particles of each of the above homopolymers or copolymers, the organic particles and the The composite particles form the protrusions on the surface of the coating. As a result, the cycle performance and safety performance of the battery core can be improved.
  • the organic particles form third agglomerates.
  • the Dv50 of the third agglomerate is 5 ⁇ m-30 ⁇ m, preferably 5.0 ⁇ m-12 ⁇ m.
  • the third agglomerate includes organic particles with primary particle morphology, and there is a gap between two adjacent organic particles. Thereby, the ion conductivity of the isolation membrane can be improved.
  • the Dv50 of the organic particles with primary particle morphology is 50 nm-400 nm, preferably 100 nm-200 nm.
  • the mass ratio of the composite particles to the organic particles is (20-90): (0-70), preferably (45-90): (0-45).
  • the average thickness of the pressure-sensitive coating is 2 ⁇ m-20 ⁇ m, optionally 2 ⁇ m-15 ⁇ m. This can ensure appropriate adhesion between the isolation film and the pole piece and improve the dynamic performance of the battery core.
  • a second aspect of the present application provides a method for preparing an isolation film, including the steps of: forming a pressure-sensitive coating on at least part of the surface of a substrate, the pressure-sensitive coating including polyacrylate particles and a first plasticizer, The composite particles form protrusions on the surface of the pressure-sensitive coating, the composite particles include polyacrylate particles and inorganic particles, the inorganic particles are between at least two of the polyacrylate particles, and the first The absolute value of the difference between the solubility parameter of the plasticizer and the solubility parameter of the composite particles is 0.3MPa 1/2 -4MPa 1/2 .
  • the isolation film of the present application has good pressure-sensitive properties and compression modulus, and its adhesive force is below 0.1N/m under the action of ⁇ 1MPa, so it can avoid the separation of layers of the isolation film during winding and storage.
  • the bonding between the layers can have obvious bonding effect with the electrode piece under the pressure of ⁇ 2MPa. Therefore, when using this isolation film to prepare the battery core, the electrode piece can be isolated from the electrode piece under normal temperature conditions and appropriate pressure.
  • the membrane adheres closely to improve the dynamic performance of the battery core.
  • a third aspect of the present application provides a battery, which includes a separator film according to the first aspect of the present application or a separator film prepared according to the method of the second aspect of the present application.
  • a fourth aspect of the present application provides an electrical device, which includes a battery according to the third aspect of the present application, where the battery is used to provide electrical energy.
  • the electrical device of the present application includes the battery provided above by the present application, and therefore has at least the same advantages as the above-mentioned battery.
  • Figure 1 is a schematic diagram of the winding of the battery core after the separator, the positive electrode piece and the negative electrode piece are stacked in an embodiment of the present application.
  • Figure 2 is a schematic structural diagram of a model of an isolation membrane in an embodiment of the present application.
  • Figure 3 is a schematic structural diagram of a battery according to an embodiment of the present application.
  • Figure 4 is a schematic structural diagram of a battery module according to an embodiment of the present application.
  • Figure 5 is a schematic structural diagram of a battery pack according to an embodiment of the present application.
  • FIG. 6 is an exploded view of FIG. 5 .
  • FIG. 7 is a schematic diagram of an embodiment of an electrical device using a battery as a power source.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with other lower limits to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed 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.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • Embodiments of the present application provide an isolation film, which includes: a base material and a pressure-sensitive coating.
  • the pressure-sensitive coating is formed on at least part of the surface of the base material.
  • the pressure-sensitive coating includes composite particles and a third A plasticizer, the composite particles form protrusions on the surface of the pressure-sensitive coating, the composite particles include polyacrylate particles and inorganic particles, and the inorganic particles are between at least two of the polyacrylate particles.
  • the absolute value of the difference between the solubility parameter of the first plasticizer and the solubility parameter of the composite particles is 0.3MPa 1/2 -4MPa 1/2 .
  • the pressure-sensitive coating is formed on at least part of the surface of the substrate, it should be understood that the pressure-sensitive coating is in direct contact with the surface of the substrate, so-called “direct contact”; or the surface of the substrate is in direct contact with the pressure-sensitive coating. There are other layers between the layers, so-called “indirect contacts”.
  • "at least two of the polyacrylate particles have inorganic particles and composite particles forming protrusions on the surface of the pressure-sensitive coating” can be achieved by cutting the isolation film along its thickness direction, and then using a scanning electron microscope ( SEM) scans the cross section of the pressure-sensitive coating of the isolation film. It can be seen from the SEM image that the composite particles include polyacrylate particles and inorganic particles, and there are inorganic particles between some polyacrylate particles and the composite particles are in the pressure-sensitive coating. surface Form a bump.
  • a ZEISS Sigma300 scanning electron microscope was used for testing.
  • the test was performed according to the following steps: First, cut the isolation film to be tested into a 6mm ⁇ 6mm sample to be tested, and clamp the sample to be tested with two pieces of conductive and thermally conductive copper foil. , stick and fix the sample to be tested and the copper foil with double-sided tape, press it with a certain 400g flat iron block for 1 hour to make the gap between the sample to be tested and the copper foil as small as possible, and then use scissors to cut the edges neatly. Stick it on the sample stage with conductive glue so that the sample slightly protrudes from the edge of the sample stage. Then put the sample stage into the sample rack and lock it.
  • the inventor found after extensive research that the pressure-sensitive coating of the isolation film used in this application includes composite particles and a first plasticizer.
  • the composite particles include polyacrylate particles and inorganic particles, and at least two polyacrylic acid particles are used. There are inorganic particles between the ester particles to avoid the adhesion of the composite particles during the high-temperature granulation process, improve the ion conductivity of the isolation membrane, and increase the compression modulus of the composite particles, making the isolation membrane and the pole piece more suitable for adhesion.
  • the isolation film coating of the present application includes composite particles and a first plasticizer, which on the one hand reduces the resistance of the isolation film, and on the other hand the first plasticizer
  • the absolute value of the difference between the solubility parameter of the agent and the solubility parameter of the composite particles is 0.3MPa 1/2 -4MPa 1/2 .
  • the first plasticizer can plasticize the composite particles, thereby improving the pressure-sensitive characteristics of the isolation film, Improve the dynamic performance of the battery core, and ensure proper bonding between the isolation film and the pole piece during the production and use of the battery core. The most important thing is to make the isolation film have an appropriate compression modulus to ensure that the battery core expands during the cycle.
  • the isolation film of the present application has good pressure-sensitive properties and compression modulus, and its adhesive force is below 0.1N/m under the action of ⁇ 1MPa, so it can avoid the separation of layers of the isolation film during winding and storage.
  • the bonding between the layers can have obvious bonding effect with the electrode piece under the pressure of ⁇ 2MPa. Therefore, when using this isolation film to prepare the battery core, the electrode piece can be isolated from the electrode piece under normal temperature conditions and appropriate pressure.
  • the membrane adheres closely to improve the dynamic performance of the battery core.
  • the inventor found that when the separator film of the present application meets the above conditions and optionally meets one or more of the following conditions, the performance of the battery can be further improved.
  • the absolute value of the difference between the solubility parameter of the first plasticizer and the solubility parameter of the composite particle is 0.3MPa 1/2 -4MPa 1/2 , for example, 0.4MPa 1/2 -3.8MPa 1/2 , 0.5MPa 1/2 -3.6MPa 1/2 , 0.7MPa 1/2 -3.5MPa 1/2 , 0.9MPa 1/2 -3.2MPa 1/2 , 1MPa 1/2 -3MPa 1/2 , 1.2MPa 1/2 -2.8MPa 1/2 , 1.5MPa 1/2 -2.5MPa 1/2 , 1.8MPa 1/2 -2.2MPa 1/2 , 2MPa 1/2 -2.2MPa 1/2 .
  • a first plasticizer whose solubility parameter satisfies the above difference with that of the composite particles can ensure the plasticizing effect of the first plasticizer on the composite particles, thereby improving the pressure-sensitive characteristics of the isolation film and improving the dynamics of the battery core. performance.
  • the solubility parameter SP (E/V) 1/2 of the first plasticizer
  • E is the cohesive energy in J
  • V is the volume in m 3
  • E/V is the cohesive energy density.
  • there are many measurement methods. For example, you can measure the boiling point of a substance and use the empirical formula of boiling point T b and heat of vaporization ⁇ H ⁇ H -2950 + 23.7T b + 0.02T b 2 to obtain the heat of vaporization ⁇ H at normal temperature.
  • the solubility parameter of the composite particles is equal to the solubility parameter of the polyacrylate particles.
  • the solubility parameter SP of the polyacrylate particles can be obtained by querying the solubility parameter of the monomer homopolymer of the polyacrylate particles.
  • the polyacrylate particles include a variety of monomers. In the case of Obtained from the square root of The mass proportion is b, and the solubility parameter of the homopolymer of monomer B is SP b ; the mass proportion of monomer C is c, and the solubility parameter of the homopolymer of monomer C is SP c , polyacrylate particles
  • the solubility parameter SP (a*SP a 2 + b*SP b 2 + c*SP c 2 ) 1/2 .
  • the first plasticizer includes an ester compound
  • the solubility parameter of the ester compound is 12MPa 1/2 -30MPa 1/2 , such as 13MPa 1/2 -29MPa 1/2 , 14MPa 1 /2 -28MPa 1/2 , 15MPa 1/2 -27MPa 1/2 , 16MPa 1/2 -26MPa 1/2 , 17MPa 1/2 -25MPa 1/2 , 18MPa 1/2 -24MPa 1/2 , 19MPa 1 /2 -23MPa 1/2 , 20MPa 1/2 -22MPa 1/2 , etc.
  • the plasticizing effect on the composite particles can be achieved and the pressure-sensitive characteristics of the isolation film can be improved.
  • ester compounds include but are not limited to carbonate compounds, carboxylate compounds, lactone compounds, etc., such as ethylene carbonate, propylene carbonate, ethyl methyl carbonate, ethyl acetate, and propyl propionate. , butyl acetate, caprolactone, diethylene glycol butyl ether acetate, etc.
  • the pressure-sensitive coating further includes an emulsifier including at least one of an anionic emulsifier and a nonionic emulsifier.
  • the addition of emulsifier can make the ester compounds evenly distributed in the composite particles, further improving the pressure-sensitive characteristics and production efficiency of the isolation film.
  • anionic emulsifiers include alkyl benzene sulfonates; nonionic emulsifiers include fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, glyceryl esters, and polyglyceryl stearic acid.
  • esters include alkyl benzene sulfonates
  • nonionic emulsifiers include fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, glyceryl esters, and polyglyceryl stearic acid.
  • esters One or more esters.
  • the pressure-sensitive coating includes 80-96 parts by weight of composite particles, 5-30 parts by weight of ester compounds, and 0.1-0.5 parts by weight of emulsifier, for example, 82 parts by weight parts by weight - 94 parts by weight of composite particles, 84 parts by weight - 92 parts by weight of composite particles, 86 parts by weight - 90 parts by weight of composite particles, 88 parts by weight - 90 parts by weight of composite particles; 6 parts by weight - 28 parts by weight Ester compounds, 8 parts by weight - 26 parts by weight of ester compounds, 10 parts by weight - 25 parts by weight of ester compounds, 12 parts by weight - 22 parts by weight of ester compounds, 15 parts by weight - 20 parts by weight of ester compounds Compound, 15-18 parts by weight of ester compound; 0.2-0.5 parts by weight of emulsifier, 0.3-0.5 parts by weight of emulsifier, 0.4-0.5 parts by weight of emulsifier.
  • emulsifier for example, 82 parts by weight parts by
  • the pressure-sensitive characteristics of the pressure-sensitive coating can be further improved, so that the adhesion between the isolation film and the pole piece is appropriate, thereby improving Dynamic properties of the cell.
  • the preparation of the composite particles of the present application can refer to the following steps:
  • step (2) Add solvent and inorganic particles to the polyacrylate polymer obtained in step (1), and obtain a mixed slurry after stirring;
  • step (3) Dry the mixed slurry in step (2) to remove the solvent, and then grind and pulverize to obtain the composite particles described in the present application.
  • polymerization of polymer monomers can be carried out by polymerization methods commonly used in the art, for example, emulsion polymerization or suspension polymerization can be used for polymerization.
  • additives may also be added to the polymerization system of the polymer monomer, such as an emulsifier such as sodium lauryl sulfate and a polymerization initiator such as ammonium persulfate.
  • the polymer monomers used to prepare the polyacrylate particles include at least the following polymer monomers:
  • the first polymer monomer has at least one ester bond, which can be selected from methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, Cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-methacrylate Butyl ester, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinyl acetate , one or more of trifluoroethyl methacrylate, glycidyl methacrylate or trimethylolprop
  • the second polymer monomer which has at least one cyanide bond, can be selected from one or more of acrylonitrile, methacrylonitrile, and ethacrylonitrile, and can be further selected from acrylonitrile and methacrylonitrile. one or more;
  • the third polymer monomer which has at least one amide bond, can be one or more of acrylamide, N-methylolacrylamide, N-butoxymethacrylamide, and can be more optionally propylene.
  • the polyacrylate particles are polymerized using at least the above three polymer monomers, which can enable the separator to obtain appropriate adhesion to the pole piece and improve the dynamic performance of the battery.
  • the weight ratio of the first polymer monomer, the second polymer monomer and the third polymer monomer in forming the polyacrylate particles is 1:0-0.8:0.05-0.75, for example 1: 0.1-0.8:0.05-0.75, 1:0.1-0.7:0.05-0.75, 1:0.2-0.6:0.05-0.75, 1:0.3-0.5:0.05-0.75, 1:0.3-0.4:0.05-0.75, 1: 0-0.8:0.05-0.7, 1:0-0.8:0.1-0.7, 1:0-0.8:0.15-0.65, 1:0-0.8:0.2-0.6, 1:0-0.8:0.3-0.5, 1: 0-0.8:0.4.
  • the weight ratio of the first polymer monomer, the second polymer monomer and the third polymer monomer in forming the polyacrylate particles is 1:0.1-0.6:0.1-0.6.
  • the inorganic particles include one of silicon, aluminum, calcium, zinc, magnesium oxides, sodium sulfate, sodium benzoate, calcium carbonate and modified materials thereof, or Several types can be selected, including one or more of silica, silica sol, alumina, zinc oxide, magnesium oxide, and sodium benzoate. Fumed silica, silica powder, alumina, and sodium benzoate can also be selected. one or more of them.
  • the Dv50 of the composite particles is ⁇ 2.5 ⁇ m, such as 2.5 ⁇ m-10 ⁇ m, 2.5 ⁇ m-8 ⁇ m, 2.5 ⁇ m-6 ⁇ m, 2.5 ⁇ m-5 ⁇ m, 2.5 ⁇ m-4 ⁇ m, 2.5 ⁇ m. -3 ⁇ m etc. Therefore, on the one hand, composite particles that meet the Dv50 range can provide appropriate adhesion between the pressure-sensitive coating of the isolation film and the pole piece. On the other hand, it is beneficial to form a protruding structure on the surface of the pressure-sensitive coating, thereby improving the electrical conductivity. dynamic properties of the core.
  • the isolation film of the present application there is a first agglomerate between the polyacrylate particles, and the first agglomerate includes at least two inorganic particles. Therefore, on the one hand, the composite particles are not too soft, thereby ensuring that the interaction between the composite particles and the pole pieces and between the composite particles and the substrate is appropriate when the battery expands or is subjected to relatively large external forces, thereby improving the battery dynamic performance.
  • the composite particles will not fuse and block the ion transport channels during the production process, and when there are first agglomerates formed by inorganic particulate matter inside or on the surface of the composite particles, at high temperatures such as ⁇ 45°C and When the stress state is ⁇ 0.4MPa, it is ensured that the spherical main body of the composite particles will not soften and collapse, thereby ensuring proper interaction between the composite particles and the pole pieces, as well as the composite particles and the substrate, thereby curbing the deterioration of the battery cycle performance and further improving the battery Dynamic properties.
  • 0.01 ⁇ m ⁇ Dv50 of the first agglomerate ⁇ Dv10 of the composite particle 0.01 ⁇ m ⁇ Dv50 of the first agglomerate ⁇ Dv10 of the composite particle.
  • the composite particles include inorganic particles in the form of primary particles.
  • the Dv50 of the inorganic particles with primary particle morphology is 0.01 ⁇ m-1 ⁇ m, such as 0.01 ⁇ m-0.8 ⁇ m, 0.05 ⁇ m-1 ⁇ m, 0.1 ⁇ m-1 ⁇ m, 0.2 ⁇ m-1 ⁇ m, 0.3 ⁇ m-1 ⁇ m, 0.4 ⁇ m- 1 ⁇ m, 0.5 ⁇ m-1 ⁇ m, 0.6 ⁇ m-1 ⁇ m, 0.7 ⁇ m-1 ⁇ m, 0.8 ⁇ m-1 ⁇ m, 0.9 ⁇ m-1 ⁇ m, etc.
  • inorganic particles that meet the Dv50 can enable the separator film to obtain an appropriate compressive modulus, thereby improving the dynamic performance of the battery.
  • the Dv50 of the primary particle morphology inorganic particles is 0.5 ⁇ m to 1 ⁇ m. As a result, the dynamic performance of the battery can be improved.
  • Primary particles and secondary particles have well-known meanings in the art.
  • Primary particles refer to particles that have not formed an agglomerated state.
  • Secondary particles refer to agglomerated particles formed by the aggregation of two or more primary particles.
  • Primary and secondary particles can be easily distinguished by scanning electron microscopy (SEM) images.
  • the composite particles include a second agglomerate, and the second agglomerate includes at least two of the polyacrylate particles. This prevents the composite particles from being too soft, thereby ensuring that the interaction between the composite particles and the pole pieces and between the composite particles and the separator substrate is appropriate when the battery expands or is subjected to relatively large external forces, thereby improving the battery dynamic performance.
  • the Dv50 of the second agglomerate is 0.3 ⁇ m-5 ⁇ m, such as 0.5 ⁇ m-5 ⁇ m, 0.7 ⁇ m-4.5 ⁇ m, 1 ⁇ m-4 ⁇ m, 1.3 ⁇ m-3.5 ⁇ m, 1.5 ⁇ m-3.2 ⁇ m, 1.7 ⁇ m-3 ⁇ m, 2 ⁇ m-2.8 ⁇ m, 2 ⁇ m-2.5 ⁇ m, 5 ⁇ m-10 ⁇ m, 5 ⁇ m-9 ⁇ m, 5 ⁇ m-8 ⁇ m, 5 ⁇ m-7 ⁇ m, 5 ⁇ m-6 ⁇ m, etc.
  • the The Dv50 of the dimer is 1m-2 ⁇ m.
  • the polyacrylate particles include polyacrylate particles with a primary particle morphology and/or polyacrylate particles with a secondary particle morphology, wherein the primary particle morphology
  • the Dv50 of polyacrylate particles is 50nm-400nm, such as 50nm-375nm, 75nm-375nm, 100nm-350nm, 125nm-325nm, 150nm-300nm, 175nm-275nm, 200nm-250nm, 200nm-225nm, etc.
  • the Dv50 of the primary particle morphology polyacrylate particles is 100 nm-200 nm.
  • the Dv50 of the polyacrylate particles with secondary particle morphology is 2 ⁇ m-15 ⁇ m, such as 3 ⁇ m-15 ⁇ m, 4 ⁇ m-12 ⁇ m, 5 ⁇ m-10 ⁇ m, 5 ⁇ m-8 ⁇ m, 5 ⁇ m-7 ⁇ m, 5 ⁇ m-6 ⁇ m, etc.
  • the content of the inorganic particles in the composite particles is 1wt%-50wt%, such as 1wt%-48wt%, 1wt%-45wt%, 1wt%-40wt%, 1wt%-35wt%, 1wt %-30wt%, 1wt%-25wt%, 1wt%-20wt%, 1wt%-15wt%, 2wt%-15wt%, 3wt%-15wt%, 4wt%-15wt%, 5wt%-15wt%, 7wt%- 15wt%, 10wt%-15wt%, 12wt%-15wt%, etc. Therefore, the content of inorganic particles in the composite particles is controlled within the above content range.
  • the polyacrylate particles will not be bonded due to the high-temperature treatment in the granulation process, thereby improving the ion conduction ability of the isolation film; on the other hand, making the isolation film have an appropriate compression modulus can ensure that there is an appropriate force between the isolation film coating and the anode when the battery module is under stress.
  • the glass transition temperature of the polyacrylate particles is 20°C-80°C, such as 25°C-75°C, 30°C-70°C, 35°C-65°C, 40°C-60°C, 45 °C-55°C, 45°C-50°C. Therefore, using polyacrylate particles that meet the glass transition temperature can avoid the adhesion of composite particles during the high-temperature granulation process and improve the ion conductivity of the isolation film. In other embodiments, the polyacrylate particles have a glass transition temperature of 25°C to 65°C.
  • protrusions are formed on the surface of the isolation film coating of the present application and the double-sided height of the protrusions is 15 ⁇ m-60 ⁇ m, such as 15 ⁇ m-58 ⁇ m, 16 ⁇ m-56 ⁇ m, 18 ⁇ m-55 ⁇ m, 20 ⁇ m-52 ⁇ m, 22 ⁇ m-40 ⁇ m, 25 ⁇ m-40 ⁇ m, 25 ⁇ m-38 ⁇ m, 25 ⁇ m-36 ⁇ m, 28 ⁇ m-35 ⁇ m, 30 ⁇ m-32 ⁇ m, etc.
  • the protrusions in this height range can provide an appropriate space between the isolation film and the pole piece to release stress, prevent the pole piece from breaking during the winding process, and improve safety; on the other hand, the space between the isolation film and the pole piece can be Leave appropriate gaps to facilitate the flow and infiltration of electrolyte and improve the dynamic performance of the battery core. Further, the convex surface has first agglomerates. Therefore, the protrusion can provide appropriate adhesion between the separator film and the pole piece, thereby improving the dynamic performance of the battery.
  • pressure-sensitive coatings are formed on both opposing surfaces of the substrate.
  • the sum of the heights of the bulges on the pressure-sensitive coatings on both sides is the double-sided height of the bulges.
  • the test method for the double-sided height of the bulges includes: Reference Figure 1. First, the negative electrode piece, isolation film and positive electrode piece are stacked in order to form a battery core and then rolled up (the outermost layer of the battery cell ends with the convex surface of the positive electrode piece), and then the CT equipment (ZEISS-1500) is used to wind it Scan at a distance of 15 ⁇ 1mm from the edge of the negative electrode plate at the corner of the battery cell.
  • the CT equipment ZEISS-1500
  • samples are taken along the horizontal & oblique angles (30-45°), and lines are drawn in the direction with the largest gap;
  • the inner 5-fold sampling position is From the convex surface of the innermost positive electrode piece to the convex surface of the fifth positive electrode piece, the average value is taken at 40% off;
  • the sampling position after 40% fold is from the convex surface of the inner positive electrode piece to the convex surface of the outer positive electrode piece, and the value is taken at every 50% discount.
  • Average value of the inner 5-layer gap [CT measurement distance - 4* thickness of the negative electrode piece after cold pressing * (1 + rebound rate of the negative electrode piece) - 4 * thickness of the positive electrode piece after cold pressing (1 + rebound rate of the positive electrode piece) - 8*isolation film thickness]/8
  • Average gap value after inner 6-10 layers [CT measurement distance-5*thickness of negative electrode piece after cold pressing*(1+rebound rate of negative electrode piece)-5*thickness of positive electrode piece after cold pressing (1+rebound rate of positive electrode piece rate)-10*isolation film thickness]/10
  • the rebound rate of the negative electrode piece (thickness of the negative electrode piece before entering the case - thickness of the negative electrode piece after cold pressing) / thickness of the negative electrode piece after cold pressing;
  • Rebound rate of positive electrode piece (thickness of positive electrode piece before entering the case - thickness of positive electrode piece after cold pressing) / thickness of positive electrode piece after cold pressing;
  • the raised double-sided height of the isolation film (the average gap value of the inner 5 layers + the average gap value after the inner 6-10 layers)/2.
  • the pressure-sensitive coating further includes 4-20 parts by weight of a pressure-sensitive adhesive polymer, such as 5-18 parts by weight, 7-16 parts by weight, 9-15 parts by weight, 11- 15 parts by weight, and the pressure-sensitive adhesive polymer includes an adhesive polymer and a second plasticizer.
  • the binder polymer and the second plasticizer work together to make the pressure
  • the force-sensitive adhesive polymer has good pressure-sensitive properties, which further makes the isolation film have good pressure-sensitive properties, which further makes the isolation film have good pressure-sensitive properties, so that the adhesive force is 0.1N under the action of ⁇ 1MPa.
  • the isolation film can avoid the adhesion between layers of the isolation film during the winding and storage process, and enable it to have obvious adhesion with the pole piece under the pressure of ⁇ 2MPa. Therefore, when using this When the isolation film is used to prepare the battery core, the pole piece and the isolation film can be closely attached under normal temperature conditions and appropriate pressure. On the one hand, it can avoid misalignment between the pole piece and the isolation film, which will cause the battery core to be scrapped and affect the performance and safety of the battery core. Safety risks arise.
  • the tunnel furnace and the second composite process in the traditional battery core production process can be omitted, which can save production space and production time, reduce energy consumption, significantly increase the production capacity of battery cores, and at the same time, Improve the shaping performance, safety performance and dynamic performance of the battery cell, thereby improving the safety performance and dynamic performance of the secondary battery containing the battery cell and the electrical device containing the secondary battery.
  • the mass ratio of the adhesive polymer and the second plasticizer included in the pressure-sensitive adhesive polymer may be (4-19):1, for example (4-18): 1, (4-15): 1, (4-12): 1, (4-11): 1, (4-10): 1, (4-8): 1, (4-6): 1.
  • the relative content of the second plasticizer included in the pressure-sensitive adhesive polymer is within the above range, which can ensure a greater bonding force between the pole piece and the isolation film without causing an increase in the resistance of the isolation film. The cycle performance of the secondary battery is reduced.
  • the second plasticizer content can be determined by using the instrument model STA449F3 thermogravimetric analyzer from Shimadzu Corporation of Japan.
  • the test method is as follows: take about 10 mg of pressure-sensitive adhesive polymer solid, the original mass is recorded as M0, the temperature is raised to 200°C, the mass is recorded as M1, the plasticizer content is M0-M1, the adhesive The content of the binder polymer is M0-(M0-M1).
  • the test conditions are set as: temperature range -100-400°C, nitrogen atmosphere, 10°C/min.
  • the pressure-sensitive adhesive polymer may be a core-shell structure, and the adhesive polymer and a second plasticizer may be included in both the core and the outer shell of the core-shell structure, wherein the core
  • the mass ratio of the adhesive polymer and the second plasticizer in the structure can be (2-5):1, for example (3-4):1.
  • the mass ratio of the adhesive polymer and the second plasticizer can be (2-5):1, for example (3-4):1.
  • the mass ratio of the two plasticizers can be (6-10):1, for example (7-9):1, (7-8):1.
  • the core and shell of the core-shell structure are composed of an adhesive polymer and a second plasticizer, which can further improve the pressure-sensitive performance of the pressure-sensitive adhesive polymer, thereby further improving the dynamic performance of the isolation membrane.
  • the pressure-sensitive adhesive polymer contains a second plasticizer. Under a certain pressure (for example, 1MPa-2MPa), the second plasticizer can quickly migrate to the adhesive polymer and Between the main materials of the separator, plasticize the adhesive polymer to stretch its molecular chain, and interact with the SBR adhesive in the negative electrode sheet, CMC thickener, and the adhesive in the positive electrode sheet such as PVDF. Intermolecular hydrogen bonding occurs and interface wetting is improved, enhancing the riveting effect between the two interfaces. Under the action of ⁇ 2MPa, the core structure is crushed and the second plasticizer in the core is released, which can further enhance the above effects.
  • a portion of the second plasticizer is grafted onto the adhesive polymer.
  • at least 5 wt% of the second plasticizer is grafted onto the binder polymer, based on the weight of the plasticizer.
  • the isolation film and the pole piece can form a "coupling" effect, which can improve the durability of room temperature bonding and reduce rebound. It can further ensure that too much second plasticizer will not migrate to the electrolyte during the circulation process and affect the performance of the battery core.
  • the grafting rate can be detected through infrared testing methods, specifically: the adhesive polymer, second plasticizer, and pressure-sensitive adhesive polymer are tested to obtain their Fourier transform infrared spectra. A peak appears at the position of 1500cm -1 -1700cm -1 of the adhesive polymer that is different from the adhesive polymer and the independent second plasticizer. This peak represents the grafted second plasticizer. Below the peak The area represents the amount of grafted second plasticizer, from which the grafting rate of the second plasticizer can be calculated.
  • the average particle size of the adhesive polymer may be 0.5 ⁇ m-3.0 ⁇ m, such as 0.8 ⁇ m-2.8 ⁇ m, 1 ⁇ m-2.5 ⁇ m, 1.2 ⁇ m-2.3 ⁇ m, 1.5 ⁇ m-2 ⁇ m, 1.8 ⁇ m. -2 ⁇ m.
  • the adhesive polymer that meets the average particle size of this application helps the pressure-sensitive adhesive polymer to be evenly distributed on the composite particles, and helps the core and outer shell to bond with the pole piece under a certain pressure.
  • the pressure-sensitive adhesive polymer may have an average particle size of 0.8 ⁇ m to 2 ⁇ m.
  • the average particle size of the pressure-sensitive adhesive polymer can refer to the standard GB/T 19077.1-2016. Measured by optical particle size analyzer (such as Malvern Master Size 3000).
  • the DSC melting point of the pressure-sensitive adhesive polymer may be -50°C-100°C, such as -45°C-95°C, -40°C-90°C, -35°C-85°C, -30°C-80°C, -25°C-75°C, -20°C-70°C, -15°C-65°C, -10°C-60°C, -5°C-55°C, 0°C-50°C, 5°C -45°C, 10°C-40°C, 15°C-35°C, 20°C-30°C, 25°C-30°C.
  • the pressure-sensitive adhesive polymer that meets the above DSC melting point can ensure the bonding force at room temperature and avoid the excessive bonding force at 1MPa causing the isolation film to be rolled up and bonded; at the same time, it can avoid the bonding at room temperature of 2MPa. If the adhesive force is too small, the isolation film and the pole piece will be weakly bonded, which is not conducive to battery core shaping.
  • DSC melting point is a well-known meaning in the art, and can be measured using instruments and methods known in the art.
  • it can be a DSC melting point tester with the instrument model DSC 200F3 from the German NETZSC company.
  • the test method is as follows: take about 10mg sample for testing.
  • the test conditions are set as follows: temperature range: -100-200°C, nitrogen atmosphere, 10°C/min. When the temperature is raised for the first time, the temperature corresponding to the absorption peak is the corresponding DSC melting point.
  • the adhesive polymer includes at least one of the following first monomers, at least one of the second monomers, at least one of the third monomers, and a reactive dispersant A copolymer formed by copolymerization of a reactive monomer mixture of at least one of:
  • First monomer its melting point is generally higher than 80°C, including acrylic acid, methacrylic acid, methyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, hydroxymethylacrylamide, acrylamide, benzene Ethylene, acrylonitrile;
  • Second monomer its melting point generally does not exceed 80°C, including C4-C22 alkyl acrylate, isobutyl acrylate, isooctyl acrylate, tert-butyl acrylate, and 2-ethylhexyl acrylate (isooctyl acrylate) , cyclohexyl acrylate, ethyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, acrylic acid -2-hydroxyethyl ester, 2-hydroxypropyl acrylate, ethylene urea ethyl methacrylate, dicyclopentene ethoxy methacrylate, tetrahydrofuran ester methacrylate, trifluoroethyl methacrylate, Dimethylaminoethyl methacryl
  • Third monomer including 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid Diethylaminoethyl ester, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, 3-methacryloyloxypropyltrimethoxysilane, N-hydroxymethyl Acrylamide, N-butoxymethyl (meth)acrylamide, diacetone acrylamide, ethyl methacrylate acetoacetate, divinylbenzene, epoxy resin with an epoxy value of 0.35-0.50, divinylbenzene;
  • Reactive dispersants including polyvinyl alcohol, polypropylene alcohol, polypropylene glycol, polyethylene glycol, and polyvinyl alcohol.
  • these reactive dispersants have an alcoholysis degree of ⁇ 85% and an average polymerization degree of 400-2000; preferably, the alcoholysis degree is ⁇ 88% and the average polymerization degree is 500-1600.
  • the adhesive polymer of this composition has suitable swelling, pressure sensitivity and adhesive properties, as well as a suitable elastic modulus, so that the battery core has excellent shaping effect, dynamic performance and safety performance.
  • degree of alcoholysis refers to the percentage of hydroxyl groups in the original group in the product obtained after alcoholysis, and the unit is mole fraction %. For example, there are 100 original groups (ester groups) and 60 hydroxyl groups after alcoholysis, so the degree of alcoholysis is 60%.
  • the term "average degree of polymerization” means that the polymer is composed of homogeneous polymer molecules with different degrees of polymerization, and the degree of polymerization has a statistical average significance.
  • the average degree of polymerization is the number average degree of polymerization.
  • the second plasticizer may include glycerol C4-C10 alkyl diether or monoether, glycerol C4-C10 carboxylic acid monoester or diester, propylene glycol C4-C10 alkyl monoether and glycerol. at least one of.
  • the pressure-sensitive adhesive polymer can be synthesized according to the following synthesis method, including the following steps:
  • the first step in the solvent (such as deionized water), 0.1 mass%-1 mass% (which is relative to the amount in the synthesis
  • the reactive monomer mixture including the first monomer, the second monomer, the third monomer and the reactive dispersant) and auxiliaries (including emulsifiers, stabilizers, water-based initiators) added when the pressure-sensitive adhesive polymer is used
  • the total weight of the agent) and the second plasticizer the same below) emulsifier (such as allyl sulfonate), 2 mass%-3 mass%, number average molecular weight ⁇ 1000, melting point at 0°C-30°C
  • the homogenizer speed is controlled at 8000r/min-12000r/min, such as 10000r/min for dispersion.
  • the dispersion time can be 20min-60min, such as 50min.
  • Dispersion reaction temperature The temperature is 20°C-40°C, such as 25°C, to obtain the first mixed liquid.
  • the second step add 1% to 4% by mass of a stabilizer to the first mixed solution, such as polyethylene oxide, allyl polyether sulfate, methylene succinic acid (itaconic acid), styrene At least one of sulfonic acid, sodium vinyl sulfonate and sodium nanocellulose; the homogenizer speed is controlled at 6000r/min-8000r/min, such as 6500r/min for mixing, and the time is 20min-60min, such as 30min, mixing The reaction temperature is 20°C-60°C, such as 45°C, to obtain a second mixed liquid.
  • a stabilizer such as polyethylene oxide, allyl polyether sulfate, methylene succinic acid (itaconic acid), styrene
  • the homogenizer speed is controlled at 6000r/min-8000r/min, such as 6500r/min for mixing, and the time is 20min-60min, such as 30min, mixing
  • the reaction temperature is 20°C-60°C,
  • the third step is to add 0.05% to 0.5% by mass of aqueous initiator to the second mixed solution, including sodium bicarbonate, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and tert-butyl initiator.
  • aqueous initiator including sodium bicarbonate, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and tert-butyl initiator.
  • Hydrogen peroxide di-tert-butyl peroxide, dicumyl peroxide, tert-butyl peroxide benzoate, tert-butyl peroxide tert-valerate, methyl ethyl ketone peroxide, cyclohexanone peroxide dicarbonate peroxide At least one of isopropyl ester, dicyclohexyl peroxydicarbonate, potassium persulfate, sodium persulfate, ammonium persulfate, azobisisobutyronitrile and azobisisoheptanitrile.
  • the homogenizer speed is controlled at 8000r/min-12000r/min, such as 8000r/min for mixing, and the mixing time is 20min-60min, such as 30min.
  • the reaction temperature is 60°C-80°C, such as 72°C, to obtain a third mixed liquid.
  • the reaction time is 80min-100min, such as 80min, to obtain the fourth mixture.
  • the fifth step is to continue the reaction of the fourth mixture at a reaction temperature of 80°C-90°C, such as 84°C, and a homogenizer speed of 12000r/min-18000r/min, such as 15000r/min, for a time of 120min-240min. , such as 180min, the fifth mixture is obtained.
  • the sixth step is to add 10% to 20% by mass of a second plasticizer, such as glycerol, to the fifth mixture.
  • a second plasticizer such as glycerol
  • the reaction temperature is controlled to 80°C to 90°C, such as 84°C; the homogenizer speed is controlled to 12000r/min. -18000r/min, such as 15000r/min, the reaction time is 120min-240min, such as 180min, and the sixth mixture is obtained.
  • 0.05 mass% to 0.5 mass% of an aqueous initiator such as ammonium persulfate-sodium bicarbonate
  • the homogenizer speed control is 8000r/min-12000r/min, such as 8000r/min, and the time is 20-60min, such as 30min.
  • the reaction temperature is 60°C-80°C, such as 72°C, and a seventh mixture is obtained.
  • the homogenizer speed is 100r/min-1000r/min, such as 400r/min, gradually and evenly drop 30 mass%-40 mass% into the seventh mixture (control it to finish dripping in 60 minutes)
  • the reaction monomer mixture is reacted for a reaction time of 100 min-160 min, such as 120 min, to obtain an eighth mixture.
  • the ninth step add 5% to 20% by mass of a second plasticizer, such as glycerin, to the eighth mixture, control the reaction temperature to 80°C to 90°C, such as 84°C; the homogenizer speed is 12000r/min- 18000r/min, such as 15000r/min, and the time is 120min-240min, such as 180min, to obtain the ninth mixture.
  • a second plasticizer such as glycerin
  • the temperature of the ninth mixture is lowered to below 50°C, and the material is filtered to obtain a pressure-sensitive adhesive polymer with a core-shell structure.
  • steps 7 to 9 the temperature of the ninth mixture is lowered to below 50°C, and the material is filtered to obtain a pressure-sensitive adhesive polymer with a core-shell structure.
  • the pressure-sensitive coating has an average thickness of 2 ⁇ m-20 ⁇ m, such as 4 ⁇ m-18 ⁇ m, 5 ⁇ m-15 ⁇ m, 7 ⁇ m-12 ⁇ m, 10 ⁇ m-12 ⁇ m.
  • the pressure-sensitive coating has an average thickness of 2 ⁇ m to 15 ⁇ m.
  • the isolation film coating of the present application may also include organic particles, wherein the organic particles include polytetrafluoroethylene particles, polychlorotrifluoroethylene particles, polyvinyl fluoride particles, and polyvinylidene fluoride particles.
  • the organic particles of the barrier film coating of the present application form third agglomerates.
  • the Dv50 of the third agglomerate is 5 ⁇ m-30 ⁇ m, such as 5 ⁇ m-28 ⁇ m, 5 ⁇ m-25 ⁇ m, 5 ⁇ m-22 ⁇ m, 5 ⁇ m-20 ⁇ m, 5 ⁇ m-20 ⁇ m, 5 ⁇ m-18 ⁇ m, 5 ⁇ m-15 ⁇ m, 5 ⁇ m-12 ⁇ m, 5 ⁇ m- 10 ⁇ m, 5 ⁇ m-8 ⁇ m, 5 ⁇ m-6 ⁇ m, etc.
  • the third agglomerate includes organic particles with primary particle morphology, and there is a gap between two adjacent organic particles. This gap can serve as an ion transmission channel, thereby increasing the ion conductivity of the isolation membrane.
  • the Dv50 of the organic particles with primary particle morphology is 50nm-400nm, such as 50nm-375nm, 75nm-375nm, 100nm-350nm, 125nm-325nm, 150nm-300nm, 175nm-275nm, 200nm-250nm. , 200nm-225nm, etc. In other embodiments, the Dv50 of the organic particles with primary particle morphology is 100nm-200nm.
  • Dv50 refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 50%
  • Dv10 refers to the particle size corresponding to the cumulative volume distribution percentage reaching 10%
  • the Dv10 of the composite particles and the Dv50 of the composite particles can be measured using laser diffraction particle size analysis.
  • a laser particle size analyzer such as Malvern Master Size 3000
  • the Dv50 of inorganic particles with primary particle morphology, the Dv50 of polyacrylate particles with primary particle morphology, and the Dv50 of polyacrylate particles with secondary particle morphology can be calculated statistically from the SEM images of the isolation film, for example, take 10Kx For the SEM image of the isolation film at the magnification, use 5 parallel samples for each sample, use 10 positions for each parallel sample, select 20 points at each position for statistics, and finally take the average value to determine the corresponding particle size.
  • the Dv50 of the first agglomerate, the Dv50 of the second agglomerate and the Dv50 of the third agglomerate can be statistically obtained using the CP chart of the isolation film. For example, take the CP chart of the isolation film with a magnification of 5Kx, and use 5 for each sample. Parallel samples, each parallel sample uses 10 positions, 20 points are selected at each position for statistics, and the final average is the corresponding particle size.
  • the mass ratio of the composite particles to the organic particles is (20-90): (0-70).
  • the mass ratio of the composite particles to the polyvinylidene fluoride particles is (20-90). ): (5 ⁇ 65), (20 ⁇ 90): (10 ⁇ 60), (20 ⁇ 90): (20 ⁇ 50), (20 ⁇ 90): (30 ⁇ 40), (30 ⁇ 80): (0 ⁇ 70), (40 ⁇ 70): (0 ⁇ 70), (50 ⁇ 60): (0 ⁇ 70), (30 ⁇ 80): (5 ⁇ 65), (40 ⁇ 65): (10 ⁇ 55), (45 ⁇ 60): (20 ⁇ 45), (55 ⁇ 60): (30 ⁇ 45).
  • the mass ratio of the composite particles to the organic particles is (45-90): (0-45). As a result, battery safety performance and cycle performance can be improved.
  • the isolation film includes a base material and a pressure-sensitive coating (not shown).
  • the pressure-sensitive coating includes composite particles, organic particles, a first plasticizer, an emulsifier and an adhesive. , the first plasticizer and emulsifier are evenly distributed inside and between the composite particles, the composite particles and the organic particles are connected to the base material through an adhesive, and the composite particles and the organic particles are Protrusions are formed on the surface of the pressure-sensitive coating.
  • the pressure-sensitive coating may also include other organic compounds, such as polymers that improve heat resistance, dispersants, wetting agents, and other types of adhesives.
  • the other organic compounds mentioned above are all non-granular substances in the pressure-sensitive coating. This application has no special restrictions on the types of other organic compounds mentioned above, and any well-known materials with good improved properties can be selected.
  • the base material is a porous structure membrane material with good chemical stability and mechanical stability.
  • the substrate can be a single-layer film material or a multi-layer composite film material.
  • the materials of each layer can be the same or different.
  • the substrate in the isolation film of the present application, can be a porous film or a porous nonwoven mesh containing one or more of the following: polyethylene, polypropylene, polyethylene terephthalate glycol Ester, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamide Imide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymer, polyphenylene sulfide and polyvinyl naphthalene.
  • the substrate is a porous film or porous nonwoven web comprising polyethylene and/or polypropylene.
  • the above-mentioned base material is used to prepare the isolation film, which is conducive to the combination of the base material and the coating through the adhesive to form a moderately dense, porous isolation film that can conduct lithium ions.
  • the substrate in the release film of the present application, has a porosity of 10% to 95%, optionally 35% to 45%. This can improve the ion-conducting performance of the separator while reducing the probability of contact between the positive and negative electrode pieces.
  • the substrate in the isolation film of the present application, has a pore diameter of 0.1 ⁇ m to 50 ⁇ m, optionally 0.1 ⁇ m to 5 ⁇ m. Choosing a substrate with the above-mentioned pore structure enables the isolation membrane to have good ion conductivity, reducing the probability of direct contact between the positive and negative electrode pieces, thereby improving the cell dynamics and safety performance.
  • 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, or 7 ⁇ m-10 ⁇ m.
  • the thickness of the substrate is controlled within a given range, the battery energy density can be further improved while ensuring battery cycle performance and safety performance.
  • the peeling force of the pressure-sensitive coating is 40 N/m or more; after the isolation film is placed in an environment of 150°C for 1 hour without clamping, its peeling force in the longitudinal direction (MD) or transverse direction (TD) Thermal shrinkage rates are all below 5%; the heat gun damage size at 200°C is 0; the bonding force between the isolation film and the pole piece is above 1.0N/m, and the diaphragm resistance at 25°C is below 2 ohms.
  • the air permeability, transverse tensile strength (MD), longitudinal tensile strength (TD), transverse elongation at break, and longitudinal elongation at break of the isolation film all have meanings known in the art, and can be adopted in the art. Measured by known methods. For example, you can refer to the standard GB/T36363-2018 for testing.
  • the species of polyacrylate particles, ester compounds, emulsifiers, pressure-sensitive adhesive polymers, and organic particles can be tested using equipment and methods known in the art.
  • the infrared spectrum of the material can be tested to determine the characteristic peaks it contains, thereby determining the type of material.
  • infrared spectroscopic analysis of organic particles can be performed using well-known instruments and methods in the art, such as an infrared spectrometer, such as an IS10 Fourier transform infrared spectrometer from Nicolet Company in the United States, in accordance with GB/T6040-2002. General test of infrared spectroscopy analysis methods.
  • a second aspect of the application also provides a method for preparing an isolation film, including the following steps:
  • the pressure-sensitive coating including polyacrylate particles and a first plasticizer, the composite particles forming protrusions on the surface of the pressure-sensitive coating , the composite particles include polyacrylate particles and inorganic particles, at least two of the polyacrylate particles have the inorganic particles between them, and the solubility parameter of the first plasticizer is different from the solubility parameter of the composite particles.
  • the absolute value of the value is 0.3MPa 1/2 -4MPa 1/2 .
  • the base material, first plasticizer and composite particles are the same as described above and will not be described again here.
  • a release film includes a substrate and a pressure-sensitive coating disposed on only one surface of the substrate.
  • the isolation film includes a substrate and a pressure-sensitive coating, the pressure-sensitive coating being disposed on both surfaces of the substrate simultaneously.
  • step (2) can be performed using the following steps: (2-1) providing a pressure-sensitive coating slurry, the pressure-sensitive coating slurry including composite particles and a first plasticizer; (2- 2) Coat the pressure-sensitive coating slurry on at least one side of the substrate and dry to obtain the isolation film.
  • the solvent in the pressure-sensitive coating slurry may be water, such as deionized water.
  • the pressure-sensitive coating slurry may also include other organic compounds, for example, it may also include polymers, dispersants, wetting agents, and emulsions that improve heat resistance. shaped adhesive. Among them, other organic compounds are non-granular in the dried coating.
  • the solid content of the pressure-sensitive coating slurry may be controlled at 10%-20%, for example, may be 12%-15%, based on weight.
  • the manufacturing yield of the coating can be improved and the bonding performance of the coating can be improved.
  • the first plasticizer in step (2-1), includes an ester compound, and the solubility parameter of the ester compound is 12MPa 1/2 -30MPa 1/2 .
  • the pressure-sensitive coating slurry may further include an emulsifier.
  • the emulsifier includes at least one of anionic emulsifier and nonionic emulsifier.
  • the addition of emulsifier can make the ester compounds evenly distributed in the composite particles, further improving the pressure-sensitive characteristics and production efficiency of the isolation film.
  • anionic emulsifiers include alkyl benzene sulfonates; nonionic emulsifiers include fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, glyceryl esters, and polyglyceryl stearic acid.
  • esters include alkyl benzene sulfonates
  • nonionic emulsifiers include fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene ethers, glyceryl esters, and polyglyceryl stearic acid.
  • the pressure-sensitive coating slurry further includes a pressure-sensitive adhesive polymer
  • the pressure-sensitive adhesive polymer includes an adhesive polymerization substance and a second plasticizer.
  • the adhesive polymer and the second plasticizer work together to make the pressure-sensitive adhesive polymer have good pressure-sensitive properties, further making the isolation film have good pressure-sensitive properties, and further making the isolation film have good pressure-sensitive properties.
  • the pressure-sensitive characteristics make the adhesive force below 0.1N/m under the action of ⁇ 1MPa, so it can avoid the adhesion between layers of the isolation film during the rolling and storage process, and make it possible to keep it under ⁇ 2MPa. It can have obvious bonding effect with the pole piece under pressure.
  • the pole piece and the isolation film can be closely adhered to each other under normal temperature conditions and appropriate pressure.
  • the pole piece can be avoided. Misalignment between the battery core and the isolation film will cause the battery core to be scrapped, affect the battery core performance and create safety risks.
  • the tunnel furnace and the second composite process in the traditional battery core production process can be omitted, thereby saving production space and production time, and reduce energy consumption, which significantly improves the production capacity of battery cells.
  • it can improve the shaping performance, safety performance and dynamic performance of the battery cells, thereby improving the secondary batteries containing the battery cells and the uses of the secondary batteries. Safety performance and dynamic performance of electrical devices.
  • the pressure-sensitive coating slurry further includes organic particles, and the organic particles include polytetrafluoroethylene particles, polychlorotrifluoroethylene particles, polyvinyl fluoride particles, polyvinylidene fluoride particles, polyvinylidene fluoride particles, Ethylene particles, polypropylene particles, polyacrylonitrile particles, polyethylene oxide particles, copolymer particles of fluorine-containing alkenyl monomer units and vinyl monomer units, fluorine-containing alkenyl monomer units and acrylic monomer units At least one of copolymer particles, copolymer particles of fluorine-containing alkenyl monomer units and acrylic ester monomer units, and modified compound particles of each of the above homopolymers or copolymers.
  • step (2-2) the coating is performed using a coating machine.
  • the coating in step (2-2), may adopt transfer coating, spin spray coating, dip coating and other processes; for example, the coating may adopt transfer coating.
  • the coater includes a gravure roller; the gravure roller is used to transfer the coating slurry to the substrate.
  • the performance of the isolation film of the present application can be further improved.
  • Those skilled in the art can selectively regulate one or several of the above process parameters according to actual production conditions.
  • a third aspect of the present application provides a battery, which includes the isolation film of the first aspect or the isolation film prepared by the second aspect.
  • a battery refers to a battery that can be recharged to activate active materials and continue to be used after discharge.
  • a battery typically includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play the role of isolation.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the positive electrode sheet usually includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector.
  • 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 (metal materials can be placed on a polymer substrate to form a composite current collector).
  • the positive electrode current collector may be aluminum foil.
  • the specific type of the positive active material is not limited. Active materials known in the art that can be used for battery positive electrodes can be used, and those skilled in the art can select according to actual needs.
  • the positive active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, 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, lithium nickel cobalt aluminum oxide and their modifications One or more of the compounds.
  • lithium-containing phosphates with an olivine structure 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 its modified compounds. These materials are commercially available.
  • the modified compounds of each of the above materials may be doping modifications and/or surface coating modifications of the materials.
  • the positive electrode film layer usually also optionally includes adhesives, conductive agents and other optional auxiliaries.
  • the conductive agent can 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 adhesive 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), carboxymethylcellulose (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 carboxymethylcellulose
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • the negative electrode sheet usually includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector.
  • 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 placed on a polymer substrate to form a composite current collector).
  • the negative electrode current collector may be copper foil.
  • the negative active material is not limited. Active materials known in the art that can be used for battery negative electrodes can be used, and those skilled in the art can select according to actual needs.
  • the negative 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 oxide compounds (such as silicon oxide), silicon carbon composites, silicon nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. These materials are commercially available.
  • the negative active material may include silicon-based material.
  • the negative electrode film layer usually also optionally includes adhesives, conductive agents and other optional auxiliaries.
  • the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • adhesives may include 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
  • PVD polyvinyl acetate copolymer
  • EVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • auxiliaries may be thickeners and dispersants (such as carboxymethylcellulose sodium CMC-Na) and PTC thermistor materials.
  • the battery may include an electrolyte that acts to conduct ions between the positive and negative electrodes.
  • the electrolyte solution may include electrolyte salts and solvents.
  • the electrolyte salt may include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide (LiFSI ), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonylborate (LiDFOB), lithium difluoromethanesulfonylborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), one or more of lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • LiPF 6 lithium hexafluorophosphate
  • the solvent may include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dicarbonate Propyl ester (DPC), methylpropyl carbonate (MPC), ethylpropyl 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), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone ( One or more of EMS) and diethyl sulfone (ES),
  • additives are also included in the electrolyte.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, and additives that improve the low-temperature performance of the battery. additive.
  • the battery may be a lithium-ion secondary battery.
  • FIG. 3 shows a battery 1 with a square structure as an example.
  • the battery may include an outer packaging.
  • the outer packaging is used to package the positive electrode piece, the negative electrode piece and the electrolyte.
  • the outer packaging may include a shell and a cover.
  • the housing may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity.
  • the housing has an opening communicating with the accommodation cavity, and the cover plate can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into an electrode assembly through a winding process or a lamination process.
  • the electrode assembly is packaged in the containing cavity.
  • the electrolyte can be electrolyte, and the electrolyte is infiltrated into the electrode assembly.
  • the number of electrode components contained in the battery can be one or several, which can be adjusted according to needs.
  • the outer packaging of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.
  • the outer packaging of the battery can also be a soft bag, such as a bag-type soft bag.
  • the soft bag may be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PBS polybutylene succinate
  • the batteries can be assembled into a battery module, and the number of batteries contained in the battery module can be multiple. The specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 4 is a battery module 2 as an example.
  • a plurality of batteries 1 may be arranged in sequence along the length direction of the battery module 2 .
  • the plurality of batteries 1 can be fixed by fasteners.
  • the battery module 2 may further include a housing having an accommodation space in which a plurality of secondary batteries 1 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack 3 may include a battery box and a plurality of battery modules 2 disposed in the battery box.
  • the battery box includes an upper box 4 and a lower box 5 .
  • the upper box 4 can be covered with the lower box 5 and form a closed space for accommodating the battery module 2 .
  • Multiple battery modules 2 can be arranged in the battery box in any manner.
  • the electrical device includes the battery, and the battery is used to provide electrical energy.
  • the battery can be used as a power source for the electric device or as an energy storage unit of the electric device.
  • the electrical device may be, but is not limited to, a mobile device (such as a mobile phone, a laptop), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, or an electric golf ball). golf carts, electric trucks), electric trains, ships and satellites, and energy storage systems.
  • Fig. 7 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • the power-consuming device may be a mobile phone, a tablet computer, or a laptop computer.
  • the electrical device is usually required to be thin and light, and a battery can be used as the power source.
  • PE base material with a thickness of 9 ⁇ m, a pore diameter of 50 nm, and a porosity of 38%.
  • step (3) Coat the pressure-sensitive coating slurry prepared in step (2) on the two surfaces of the PE substrate with a coater and then dry to obtain the isolation film 1, and the isolation film is pressure-sensitive coated on one side
  • the thickness of the layer is 3 ⁇ m.
  • the above composite particles are prepared through the following steps:
  • Inorganic particles can be purchased from Anhui Yishitong Technology Co., Ltd.;
  • Organic particles can be purchased from Ruyuan Dongyangguang Fluororesin Co., Ltd.;
  • the substrate can be purchased from Shanghai Enjie New Materials Co., Ltd.
  • Dispersants can be purchased from Changshu Weiyi Technology Co., Ltd.
  • Wetting agents are available from The Dow Chemical Company.
  • the first plasticizer is available from Huntsman Corporation.
  • Emulsifiers are available from BASF.
  • Pressure-sensitive adhesive polymers can be purchased from Indile Technology Group Co., Ltd.
  • the positive active material LiNi 1/3 Mn 1/3 Co 1/3 O 2 , conductive agent acetylene black, and adhesive polyvinylidene fluoride (PVDF) in the solvent N-methylpyrrolidone in a mass ratio of 94:3:3. (NMP), mix evenly to obtain a positive electrode slurry, apply the positive electrode slurry on the positive electrode current collector aluminum foil, and go through drying, cold pressing, slitting, and cutting processes to obtain the positive electrode sheet.
  • the loading capacity of the positive active material on the positive electrode sheet is 0.32g/1540.25mm 2 and the density is 3.45g/cm 3 .
  • the isolation film used is the isolation film 1 prepared above.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the concentration of LiPF 6 is 1 mol/L.
  • the positive electrode piece, isolation film, and negative electrode piece in order so that the isolation film plays an isolation role between the positive and negative electrode pieces, and then wind it to obtain the electrode assembly; place the electrode assembly in the outer packaging, and put The electrolyte prepared above is injected into the dried secondary battery, and the secondary battery is obtained through vacuum packaging, standing, forming, and shaping processes.
  • the preparation methods of the secondary batteries of Example 2-60 and Comparative Example 1-3 are similar to those of the battery of Example 1, except that different separators are used.
  • the secondary battery of Example 2-60 adopts the separator 2- 60.
  • the secondary batteries of Comparative Examples 1-3 used isolation films 61-63.
  • the testing process is as follows:
  • isolation film with a length of 300mm and a width of 100mm, as well as the positive electrode piece and the negative electrode piece prepared above.
  • At least 5 test samples should be measured in each group, and if the repeatability of the adhesion test curves of the 5 test samples is good, proceed to the next group of tests. Otherwise, further testing is required until the repeatability of the five test samples is good.
  • the testing process is as follows:
  • Isolation film preparation Cut each isolation film to be tested into samples of the same size (45.3mm*33.7mm), place the samples in an environment of 60°C for at least 4 hours, and then quickly transfer to 25°C. Keep it in grade clean glove box;
  • symmetrical battery-confined Pocket bag symmetrical battery-confined aluminum-plastic bag (aluminum-plastic bag is a general product of polypropylene and aluminum foil composite for soft-pack batteries): using Cu Foil to Cu Foil (copper foil Blank symmetrical cells assembled for copper foil) as current collectors.
  • the confinement of the Pocket bag is achieved by punching holes in the middle of the green glue.
  • Pocket bags need to be baked at 60°C for at least 4 hours before use, and then quickly transferred to a 25°C class 100 clean glove box as described in (1) above for use;
  • the voltage is ⁇ 5V
  • the current is ⁇ 400mA
  • the current accuracy is: 0.1%*100 ⁇ A.
  • the EIS measurement conditions are set to the voltage frequency 1MHz-1kHz
  • the disturbance voltage is set to 5MV
  • the clamp pressure is controlled to 0.7MPa;
  • the adhesive force of the separator to the positive electrode piece in Example 1-60 at 25°C and 7MPa is between 0.3N/m-2.3N/m; in Example 1-60 at 25°C and 7MPa
  • the adhesive force of the isolation film to the negative electrode piece in Example 60 is between 0.1N/m-0.9N/m; the adhesive force of the isolation film to the positive electrode piece in Examples 1-60 is between 1N/m and 3MPa at 95°C and 3MPa.
  • Example 1-60 The resistance of the isolation film is not higher than 2.5 ⁇ ; the cycle capacity retention rate of the battery of Examples 1-60 is better than that of Comparative Examples 1-3, which shows that the adhesive force between the isolation film and the pole piece is suitable. And the resistance is low, which can improve the dynamic performance and safety performance of the battery.

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Abstract

本申请公开了一种隔离膜及其制备方法、电池和用电装置，隔离膜包括基材和压敏涂层，压敏涂层形成在基材的至少部分表面上，压敏涂层包括复合颗粒和第一增塑剂，复合颗粒在涂层表面形成凸起，复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，至少两个聚丙烯酸酯颗粒之间具有无机颗粒，第一增塑剂的溶解度参数与复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2。

Description

隔离膜及其制备方法、电池和用电装置 技术领域
本申请属于二次电池技术领域，具体涉及一种隔离膜及其制备方法、电池和用电装置。
背景技术
在电化学器件的电芯制造过程中，极片与隔离膜在转移过程中不可避免的会发生错位，轻则会导致极片互相接触导致干电芯报废，重则极片在满充后打皱严重影响动力学性能，并降低电芯安全性能。因此目前会在隔离膜上涂敷粘接涂层，并且在电化学器件的极片与隔离膜的第一道复合中，通常会在适当的压力作用下进行预压，保证电化学器件的极片与隔离膜在进入下一道工序前有一定粘接，但是由于生产效率的要求，此时的压力及作用时间都不能满足电化学器件的极片与隔离膜达到适当的粘接。
发明内容
鉴于背景技术中存在的技术问题，本申请提供一种隔离膜，旨在满足不同压力下电化学器件的极片与隔离膜达到适当的粘接。
为了实现上述目的，本申请的第一方面提供一种隔离膜，其包括：基材和压敏涂层，所述压敏涂层形成在所述基材的至少部分表面上，所述压敏涂层包括复合颗粒和第一增塑剂，所述复合颗粒在所述压敏涂层表面形成凸起，所述复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，至少两个所述聚丙烯酸酯颗粒之间具有所述无机颗粒，所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2。
相对于现有技术，本申请至少包括如下所述的有益效果：本申请的隔离膜具有良好的压敏特性和压缩模量，其在≤1MPa作用下粘接力在0.1N/m以下，因此可以避免隔离膜在收卷及存储过程中的层与层之间的粘接，其在≥2MPa压力作用下能够与极片发生明显的粘接作用，因此在使用该隔离膜制备电芯时，在常温条件，适当压力下即可将极片与隔离膜紧密贴合，提高电芯的动力学性能。
在本申请一些实施方式中，所述第一增塑剂包括酯类化合物，所述酯类化合物的溶解度参数为12MPa1/2-30MPa1/2。由此，可以在提高压敏涂层压敏特性的同时降低复合颗粒的溶解。
在本申请一些实施方式中，所述压敏涂层还包括乳化剂，所述乳化剂包括阴离子乳化剂和非离子型乳化剂中的至少之一。由此，利于第一增塑剂均匀分布于复合颗粒中，进一步提升隔离膜的制作优率和压敏特性。
在本申请一些实施方式中，所述压敏涂层包括80重量份-96重量份的复合颗粒、5重量份-30重量份的酯类化合物和0.1重量份-0.5重量份的乳化剂。由此，使得隔离膜具有良好的压敏特性，从而提高电芯的动力学性能。
在本申请一些实施方式中，所述复合颗粒的Dv50≥2.5μm，优选2.5μm-10μm，更优选3μm-8μm。由此，利于在压敏涂层表面形成凸起结构，从而提高电芯的动力学性能。
在本申请一些实施方式中，所述复合颗粒包括第一团聚体，所述第一团聚体包括至少两个所述无机颗粒。由此，可以提升电芯的动力学性能。
在本申请一些实施方式中，0.01μm≤第一团聚体的Dv50≤复合颗粒的Dv10。由此，可以提升隔离膜的压缩模量。
在本申请一些实施方式中，所述复合颗粒包括一次颗粒形貌的无机颗粒。
在本申请一些实施方式中，所述一次颗粒形貌的无机颗粒的Dv50为0.01μm-1μm，优选为0.5μm-1μm。由此，可以确保复合颗粒在制作过程中不会发生融合而堵塞隔离膜离子 运输通道。
在本申请一些实施方式中，所述复合颗粒包括第二团聚体，所述第二团聚体包括至少两个所述聚丙烯酸酯颗粒。
在本申请一些实施方式中，所述第二团聚体的Dv50为0.3μm-5μm，优选1μm-2μm。
在本申请一些实施方式中，所述聚丙烯酸酯颗粒包括一次颗粒形貌的聚丙烯酸酯颗粒和/或二次颗粒形貌的聚丙烯酸酯颗粒。
在本申请一些实施方式中，所述一次颗粒形貌的聚丙烯酸酯颗粒的Dv50为50nm-400nm，优选100nm-200nm。由此，可以提升隔离膜压敏涂层整体的导离子能力，降低隔离膜电阻，提升电芯动力学性能。
在本申请一些实施方式中，所述二次颗粒形貌的聚丙烯酸酯颗粒的Dv50为2μm-15μm，优选5μm-8μm。由此，可以提供缓冲空间供极片间的应力释放，防止卷绕电芯拐角因应力积累而断裂。
在本申请一些实施方式中，所述复合颗粒中所述无机颗粒的含量为1wt％-50wt％，可选为1wt％-40wt％，更可选为2wt％-15wt％，最优选5wt％-15wt％。由此，使得隔离膜获得合适的压缩模量。
在本申请一些实施方式中，所述凸起的双面高度为15μm-60μm。由此，可以在提高电池安全性的同时改善电芯的动力学性能。
在本申请一些实施方式中，所述凸起的表面具有所述第一团聚体。由此，可以提高电池的动力学性能。
在本申请一些实施方式中，所述聚丙烯酸酯颗粒的玻璃化转变温度为20℃-80℃，优选为25℃-65℃。由此，可以避免复合颗粒在高温造粒过程中的粘合，提高隔离膜导离子能力。
在本申请一些实施方式中，所述压敏涂层还包括4-20重量份的压力敏感型粘接剂聚合物，所述压力敏感型粘接剂聚合物包括粘接剂聚合物和第二增塑剂。由此，可以进一步提高隔离膜的压敏特性，提高电芯的动力学性能。
在本申请一些实施方式中，所述粘接剂聚合物的平均粒径为0.5μm-3.0μm，可选为0.8μm-2.0μm。由此，利于压力敏感型粘接剂聚合物在复合颗粒间均匀分布，提高隔离膜的压敏特性。
在本申请一些实施方式中，所述压力敏感型粘接剂聚合物的DSC熔点为-50℃-100℃，可选为-45℃-60℃。由此，当所述压力敏感型粘接剂聚合物的DSC熔点在上述范围内，能够保证在常温下的粘结力，避免在1MPa下粘接力过大造成隔离膜收卷粘接；同时避免在常温2MPa下粘接力过小造成隔离膜与极片粘接较弱，不利于电芯整形。
在本申请一些实施方式中，所述粘接剂聚合物与所述第二增塑剂的质量比为(4-19)：1，可选为(4-11)：1。由此，压力敏感型粘接剂聚合物中包括的第二增塑剂的相对含量在上述范围内，能够保证极片与隔离膜在一定压力作用下获得较大的粘接力，并且不会导致隔离膜的电阻增加以及电池的循环性能下降。
在本申请一些实施方式中，所述压力敏感型粘接剂聚合物为核壳结构，所述核壳结构的内核和外壳均包括粘接剂聚合物和第二增塑剂，其中，在内核结构中所述粘接剂聚合物和第二增塑剂的质量比为(2-5)：1，可选为(3-4)：1，在外壳结构中所述粘接剂聚合物和第二增塑剂的质量比为(6-10)：1，可选为(7-9)：1。由此，可以进一步提高压力敏感型粘接剂聚合物的压敏性能，从而进一步提升电芯的动力学性能。
在本申请一些实施方式中，所述粘接剂聚合物包括以下的第一单体中的至少一种、第二单体中的至少一种、第三单体中的至少一种和反应型分散剂中的至少一种的反应单体形成的共聚物：
第一单体：包括丙烯酸、甲基丙烯酸、甲基丙烯酸甲酯、甲基丙烯酸叔丁酯、甲基丙烯酸异冰片酯、羟甲基丙烯酰胺、丙烯酰胺、苯乙烯、丙烯腈；
第二单体：包括丙烯酸C4-C22烷基酯、丙烯酸异丁酯、丙烯酸异辛酯、丙烯酸叔丁酯、 丙烯酸-2-乙基己酯(异辛酯)、丙烯酸环己酯、甲基丙烯酸乙酯、甲基丙烯酸异丁酯、甲基丙烯酸-2-乙基己酯、甲基丙烯酸正己酯、甲基丙烯酸环己酯、甲基丙烯酸苄酯、丙烯酸-2-羟乙酯、丙烯酸-2-羟丙酯、甲基丙烯酸亚乙基脲乙酯、甲基丙烯酸双环戊烯乙氧基酯、甲基丙烯酸四氢呋喃酯、甲基丙烯酸三氟乙酯、甲基丙烯酸二甲氨基乙酯、甲基丙烯酸二乙氨基乙酯、甲基丙烯酸亚乙基脲乙酯、甲基丙烯酸丙烯酯、甲基丙烯酸双环戊烯乙氧基酯、甲基丙烯酸四氢呋喃酯、甲基丙烯酸三氟乙酯；
第三单体：包括甲基丙烯酸-2-羟乙酯、甲基丙烯酸-2-羟丙酯、丙烯酸缩水甘油酯、甲基丙烯酸缩水甘油酯、甲基丙烯酸二甲氨基乙酯、甲基丙烯酸二乙氨基乙酯、乙烯基三甲氧基硅烷、乙烯基三乙氧基硅烷、乙烯基三异丙氧基硅烷、3-甲基丙烯酰氧基丙基三甲氧基硅烷、N-羟甲基丙烯酰胺、N-丁氧甲基(甲基)丙烯酰胺、二丙酮丙烯酰胺、甲基丙烯酸乙酰乙酸乙酯、二乙烯基苯、环氧值在0.35-0.50的环氧树脂、二乙烯苯；
反应型分散剂：包括聚乙烯醇、聚丙烯醇、聚丙烯乙二醇、聚乙二醇、聚乙烯酸醇。
由此，能够确保所述粘接剂聚合物合适的溶胀和粘接，保证压力敏感型粘结剂聚合物有适合的溶胀、压敏性和粘接性能，同时有合适的弹性模量，保证电芯的整形效果、动力学性能和安全性能。
在本申请一些实施方式中，所述第二增塑剂包括甘油C4-C10烷基二醚、甘油C4-C10烷基单醚、甘油C4-C10羧酸单酯、甘油C4-C10羧酸二酯、丙二醇C4-C10烷基单醚和甘油中的至少之一。
在本申请一些实施方式中，所述压敏涂层还包括有机颗粒，所述有机颗粒包括聚四氟乙烯颗粒、聚三氟氯乙烯颗粒、聚氟乙烯颗粒、聚偏二氟乙烯颗粒、聚乙烯颗粒、聚丙烯颗粒、聚丙烯腈颗粒、聚环氧乙烷颗粒、含氟烯基单体单元与乙烯基单体单元的共聚物颗粒、含氟烯基单体单元与丙烯酸类单体单元的共聚物颗粒、含氟烯基单体单元与丙烯酸酯类单体单元的共聚物颗粒，以及上述各均聚物或共聚物的改性化合物颗粒中的至少之一，所述有机颗粒和所述复合颗粒在所述涂层表面形成所述凸起。由此，可以提高电芯的循环性能和安全性能。
在本申请一些实施方式中，所述有机颗粒形成第三团聚体。
在本申请一些实施方式中，所述第三团聚体的Dv50为5μm-30μm，优选为5.0μm-12μm。
在本申请一些实施方式中，所述第三团聚体中包括一次颗粒形貌的有机颗粒，并且相邻两个所述有机颗粒之间具有间隙。由此，可以提高隔离膜的离子电导率。
在本申请一些实施方式中，所述一次颗粒形貌的有机颗粒的Dv50为50nm-400nm，优选100nm-200nm。
在本申请一些实施方式中，所述复合颗粒与所述有机颗粒的质量比为(20-90)：(0-70)，优选(45-90)：(0-45)。由此，可以在降低电池成本的同时提升其安全性能和循环性能。
在本申请一些实施方式中，所述压敏涂层的平均厚度为2μm-20μm，可选为2μm-15μm。由此，可以保证隔离膜与极片间合适的粘接力，提高电芯的动力学性能。
本申请第二方面提供一种制备隔离膜的方法，包括如下步骤：在基材的至少部分表面上形成压敏涂层，所述压敏涂层包括聚丙烯酸酯颗粒和第一增塑剂，所述复合颗粒在所述压敏涂层表面形成凸起，所述复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，至少两个所述聚丙烯酸酯颗粒之间具有所述无机颗粒，所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2。
由此，本申请的隔离膜具有良好的压敏特性和压缩模量，其在≤1MPa作用下粘接力在0.1N/m以下，因此可以避免隔离膜在收卷及存储过程中的层与层之间的粘接，其在≥2MPa压力作用下能够与极片发生明显的粘接作用，因此在使用该隔离膜制备电芯时，在常温条件，适当压力下即可将极片与隔离膜紧密贴合，提高电芯的动力学性能。
本申请的第三方面提供一种电池，其包括根据本申请第一方面的隔离膜或包括根据本申请第二方面的方法制备的隔离膜。
本申请的第四方面提供一种用电装置，其包括根据本申请第三方面的电池，所述电池用于提供电能。本申请的用电装置包括本申请上述提供的电池，因此至少具有与上述电池相同的优势。
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的附图。
图1是本申请一实施方式中隔离膜与正极极片和负极极片叠置后电芯的卷绕示意图。
图2是本申请一实施方式中隔离膜的模型结构示意图。
图3是本申请一实施方式的电池的结构示意图。
图4是本申请一实施方式的电池模块的结构示意图。
图5是本申请一实施方式的电池包的结构示意图。
图6是图5的分解图。
图7是电池用作电源的用电装置的一实施方式的示意图。
附图标记说明：
1：二次电池；2：电池模块；3：电池包；4：上箱体；5：下箱体。
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它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它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它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
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)。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包括本数，“一种或几种”中“几种”的含义是两种及两种以上。
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)。
本申请实施例提供一种隔离膜，其包括：基材和压敏涂层，所述压敏涂层形成在所述基材的至少部分表面上，所述压敏涂层包括复合颗粒和第一增塑剂，所述复合颗粒在所述压敏涂层表面形成凸起，所述复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，至少两个所述聚丙烯酸酯颗粒之间具有所述无机颗粒，所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2。
需要说明的是，所述压敏涂层形成在所述基材的至少部分表面上应理解为压敏涂层直接接触基材的表面，所谓“直接接触”；或基材表面与压敏涂层之间还有其他层，所谓“间接接触”。同时“至少两个所述聚丙烯酸酯颗粒之间具有无机颗粒以及复合颗粒在所述压敏涂层表面形成凸起”可以通过对隔离膜沿其厚度方向进行裁切，然后采用扫描电子显微镜(SEM)对隔离膜压敏涂层断面进行扫描，从SEM图上可以看出复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，并且部分聚丙烯酸酯颗粒之间具有无机颗粒且复合颗粒在压敏涂层表面 形成凸起。
具体的，使用ZEISS Sigma300扫描电子显微镜进行测试，其按照如下步骤操作来测试：首先将待测隔离膜裁成6mm×6mm的待测样品，用两片导电导热的铜箔将待测样品夹住，将待测样品与铜箔之间用双面胶粘住固定，用一定400g平整铁块压1小时，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IB-19500CP氩离子截面抛光仪电源并抽真空至10Pa-4Pa，设置氩气流量为0.15MPa和电压为8KV，以及抛光时间2小时，调整样品台为摇摆模式开始抛光，抛光结束后，使用ZEISS Sigma300扫描电子显微镜得到待测样品的离子抛光断面形貌(CP)图片。
不希望限于任何理论，发明人经大量研究发现，本申请采用的隔离膜压敏涂层包括复合颗粒和第一增塑剂，复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，并且至少两个聚丙烯酸酯颗粒之间具有无机颗粒，避免复合颗粒在高温造粒过程中的粘合，提高隔离膜导离子能力，并且可以提高复合颗粒的压缩模量，使得隔离膜与极片粘接性较合适。相较于现有隔离膜涂层采用聚偏氟乙烯颗粒，本申请的隔离膜涂层包括复合颗粒和第一增塑剂，一方面降低了隔离膜电阻，另一方面所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2，该第一增塑剂可以增塑复合颗粒，从而提高隔离膜的压敏特性，提高电芯的动力学性能，并且使在电芯制作及使用过程该隔离膜与极片之间粘接合适，最重要的使该隔离膜有合适的压缩模量，确保电芯在循环膨胀力增长的情况下不至于堵住锂离子传输通道而恶化动力学性能，从而提升电池的动力学性能。同时，电池热失控产生高温时，复合颗粒在涂层表面形成的凸起能够形成大面积的胶膜结构以减少或阻隔离子传输通道，延缓电池的热蔓延，从而有效改善电池的循环性能和高温下的安全性能。由此，本申请的隔离膜具有良好的压敏特性和压缩模量，其在≤1MPa作用下粘接力在0.1N/m以下，因此可以避免隔离膜在收卷及存储过程中的层与层之间的粘接，其在≥2MPa压力作用下能够与极片发生明显的粘接作用，因此在使用该隔离膜制备电芯时，在常温条件，适当压力下即可将极片与隔离膜紧密贴合，提高电芯的动力学性能。
本发明人经深入研究发现，当本申请的隔离膜在满足上述条件的基础上，若还可选地满足下述条件中的一个或几个时，可以进一步改善电池的性能。
在一些实施方式中，所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2，例如0.4MPa1/2-3.8MPa1/2，0.5MPa1/2-3.6MPa1/2，0.7MPa1/2-3.5MPa1/2，0.9MPa1/2-3.2MPa1/2，1MPa1/2-3MPa1/2，1.2MPa1/2-2.8MPa1/2，1.5MPa1/2-2.5MPa1/2，1.8MPa1/2-2.2MPa1/2，2MPa1/2-2.2MPa1/2。发明人发现，若第一增塑剂的溶解度参数与复合颗粒溶解度参数相差太大(超过4MPa1/2)，则第一增塑剂对复合颗粒的增塑作用较小，而若第一增塑剂的溶解度参数与复合颗粒溶解度参数相差太小(小于0.3MPa1/2)，则复合颗粒容易发生溶解，使该隔离膜在存储就发生黏附，甚至隔离膜在涂布的时候，浆料发生团聚，造成生产困难。由此，采用与复合颗粒溶解度参数满足上述差值的第一增塑剂，可以确保第一增塑剂对复合颗粒间的增塑作用，从而提高隔离膜压敏特性，提高电芯的动力学性能。
根据一些示例，第一增塑剂的溶解度参数SP＝(E/V)1/2，E为内聚能，单位为J，V为体积，单位为m3，E/V是内聚能密度，测定方法有很多种，例如可以通过测定物质的沸点，利用沸点Tb和汽化热ΔH的经验公式ΔH＝-2950+23.7Tb+0.02Tb 2求得常温下的汽化热ΔH，再根据如下公式进一步得到溶解度参数SP＝(E/V)1/2＝((ΔH-RT)/Vm)1/2，其中R表示气体常数，取值为8.31J/(mol·K)，T为常温温度，单位为K，Vm为第一增塑剂在常温下单位摩尔液态体积(m3/mol)，T为常温温度(K)。
复合颗粒的溶解度参数等于其中聚丙烯酸酯颗粒的溶解度参数，聚丙烯酸酯颗粒的溶解度参数SP可以查询其聚丙烯酸酯颗粒的单体均聚物的溶解度参数得到，聚丙烯酸酯颗粒包括多种单体的情况下，溶解度参数可由单体质量占比*单体均聚物溶解度参数的平方之和 的开方求得，例如聚丙烯酸酯包括三种单体A、B和C，单体A的质量占比为a，并且单体A的均聚物的溶解度参数为SPA；单体B的质量占比为b，并且单体B的均聚物的溶解度参数为SPb；单体C的质量占比为c，并且单体C的均聚物的溶解度参数为SPc，聚丙烯酸酯颗粒的溶解度参数SP＝(a*SPa 2 +b*SPb 2 +c*SPc 2)1/2。
在一些实施方式中，所述第一增塑剂包括酯类化合物，所述酯类化合物的溶解度参数为12MPa1/2-30MPa1/2，例如13MPa1/2-29MPa1/2，14MPa1/2-28MPa1/2，15MPa1/2-27MPa1/2，16MPa1/2-26MPa1/2，17MPa1/2-25MPa1/2，18MPa1/2-24MPa1/2，19MPa1/2-23MPa1/2，20MPa1/2-22MPa1/2等。由此，可以实现对复合颗粒的增塑作用，提高隔离膜的压敏特性。作为示例，酯类化合物包括但不限于碳酸酯类化合物、羧酸酯类化合物、内酯类化合物等类型，如碳酸乙烯酯、碳酸丙烯酯、碳酸甲乙酯、乙酸乙酯、丙酸丙酯、乙酸丁酯、己内酯、二乙二醇丁醚醋酸酯等。
在一些实施方式中，所述压敏涂层还包括乳化剂，所述乳化剂包括阴离子乳化剂和非离子型乳化剂中的至少之一。乳化剂的加入可以使得酯类化合物均匀分布于复合颗粒中，进一步提升隔离膜的压敏特性和制作优率。作为示例，阴离子乳化剂包括烷基苯磺酸盐；非离子型乳化剂包括脂肪醇聚氧乙烯醚、烷基酚聚氧乙烯醚、脂肪酸聚氧乙烯醚、甘油酯类、聚甘油硬脂酸酯的一种或几种。
在一些实施方式中，所述压敏涂层包括80重量份-96重量份的复合颗粒、5重量份-30重量份的酯类化合物和0.1重量份-0.5重量份的乳化剂，例如82重量份-94重量份的复合颗粒，84重量份-92重量份的复合颗粒，86重量份-90重量份的复合颗粒，88重量份-90重量份的复合颗粒；6重量份-28重量份的酯类化合物，8重量份-26重量份的酯类化合物，10重量份-25重量份的酯类化合物，12重量份-22重量份的酯类化合物，15重量份-20重量份的酯类化合物，15重量份-18重量份的酯类化合物；0.2重量份-0.5重量份的乳化剂，0.3重量份-0.5重量份的乳化剂，0.4重量份-0.5重量份的乳化剂。由此，当压敏涂层中复合颗粒、酯类化合物和乳化剂采用上述组成时，可以进一步提高压敏涂层的压敏特性，使得隔离膜与极片之间粘接力合适，从而提高电芯的动力学性能。
根据一个示例，本申请的复合颗粒的制备可以参考下列步骤：
(1)提供制备聚丙烯酸酯颗粒的聚合物单体，使聚合物单体聚合，获得聚丙烯酸酯的聚合物；
(2)向步骤(1)所得聚丙烯酸酯的聚合物中加入溶剂和无机颗粒，搅拌后获得混合浆料；
(3)将步骤(2)的混合浆料干燥去除溶剂，然后经研磨、粉碎后获得本申请所述的复合颗粒。
需要说明的是，聚合物单体的聚合可采用本领域通常使用的聚合方法进行，例如可采用乳液聚合或悬浮聚合方式进行聚合。
在一些实施方式中，在步骤(1)中，还可向聚合物单体的聚合体系中加入添加剂，例如乳化剂例如十二烷基硫酸钠，聚合引发剂例如过硫酸铵。
在一些实施方式中，在步骤(1)中，制备聚丙烯酸酯颗粒的聚合物单体至少包括以下聚合物单体：
第一聚合物单体，其具有至少一个酯键，可选为丙烯酸甲酯、丙烯酸乙酯、丙烯酸正丙酯、丙烯酸正丁酯、丙烯酸异丁酯、丙烯酸仲丁酯、丙烯酸叔丁酯、丙烯酸环己酯、丙烯酸月桂酯、丙烯酸-2-乙基己酯、丙烯酸-2-羟基乙酯、丙烯酸-2-羟基丙酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸正丁酯、甲基丙烯酸-2-乙基己酯、甲基丙烯酸异冰片酯、甲基丙烯酸月桂酯、甲基丙烯酸-2-羟基乙酯、甲基丙烯酸-2-羟基丙酯、乙酸乙烯酯、甲基丙烯酸三氟乙酯、甲基丙烯酸缩水甘油酯或三羟甲基丙烷三丙烯酸酯中的一种或多种，更可选为甲基丙烯酸甲酯、丙烯酸月桂酯、甲基丙烯酸月桂酯或三羟甲基丙烷三丙烯酸酯中的一种或多种；
第二聚合物单体，其具有至少一个氰键，可选为丙烯腈、甲基丙烯腈、乙基丙烯腈中的一种或多种，更可选为丙烯腈、甲基丙烯腈中的一种或多种；
第三聚合物单体，其具有至少一个酰胺键，可选为丙烯酰胺、N-羟甲基丙烯酰胺、N-丁氧基甲基丙烯酰胺中的一种或多种，更可选为丙烯酰胺、N-羟甲基丙烯酰胺中的一种或多种。
由此，聚丙烯酸酯颗粒至少采用上述三种聚合物单体聚合而成，可以使得隔离膜获得与极片合适的粘接性，提高电池的动力学性能。
在一些实施方式中，上述形成聚丙烯酸酯颗粒中第一聚合物单体、第二聚合物单体与第三聚合物单体的重量比为1:0-0.8:0.05-0.75，例如1:0.1-0.8:0.05-0.75，1:0.1-0.7:0.05-0.75，1:0.2-0.6:0.05-0.75，1:0.3-0.5:0.05-0.75，1:0.3-0.4:0.05-0.75，1:0-0.8:0.05-0.7，1:0-0.8:0.1-0.7，1:0-0.8:0.15-0.65，1:0-0.8:0.2-0.6，1:0-0.8:0.3-0.5，1:0-0.8:0.4。由此，可以提高电池动力学性能。在另一些实施方式中，上述形成聚丙烯酸酯颗粒中第一聚合物单体、第二聚合物单体与第三聚合物单体的重量比为1:0.1-0.6:0.1-0.6。
在一些实施方式中，在步骤(2)中，所述无机颗粒包括自硅、铝、钙、锌、镁的氧化物以及硫酸钠、苯甲酸钠、碳酸钙及其改性材料中的一种或几种，可选为二氧化硅、硅溶胶、氧化铝、氧化锌、氧化镁、苯甲酸钠中的一种或多种，更可选为气相法二氧化硅、硅微粉、氧化铝、苯甲酸钠中的一种或多种。
在一些实施方式中，本申请隔离膜中，所述复合颗粒的Dv50≥2.5μm，例如2.5μm-10μm，2.5μm-8μm，2.5μm-6μm，2.5μm-5μm，2.5μm-4μm，2.5μm-3μm等。由此，一方面，满足该Dv50范围内的复合颗粒可以提供隔离膜压敏涂层与极片适当的粘接力，再一方面，利于在压敏涂层表面形成凸起结构，从而提高电芯的动力学性能。
在一些实施方式中，本申请隔离膜中，所述聚丙烯酸酯颗粒之间具有第一团聚体，所述第一团聚体包括至少两个无机颗粒。由此，一方面，使复合颗粒不至于太软，从而确保电池在膨胀或者比较大的外力下，复合颗粒与极片以及复合颗粒与基材间作用合适，从而提高电池动力学性能。再一方面，可以确保复合颗粒不会在制作过程中发生融合而堵住离子运输通道，并且复合颗粒的内部或者表面存在着无机颗粒物质形成的第一团聚体时，在高温如≥45℃及受力状态≥0.4MPa时，保证复合颗粒的类球形主体不会软化坍塌，从而保证复合颗粒与极片以及复合颗粒与基材之间作用合适，从而遏制了电池循环性能的恶化，进一步提高电池动力学性能。
在一些实施方式中，0.01μm≤第一团聚体的Dv50≤复合颗粒的Dv10。由此，可以提升隔离膜的压缩模量。
在一些实施方式中，本申请隔离膜中，所述复合颗粒包括一次颗粒形貌的无机颗粒。进一步地，所述一次颗粒形貌的无机颗粒的Dv50为0.01μm-1μm，例如0.01μm-0.8μm，0.05μm-1μm，0.1μm-1μm，0.2μm-1μm，0.3μm-1μm，0.4μm-1μm，0.5μm-1μm，0.6μm-1μm，0.7μm-1μm，0.8μm-1μm，0.9μm-1μm等。由此，满足该Dv50的无机颗粒可以使得隔离膜获得合适的压缩模量，从而提升电池的动力学性能。在另一些实施方式中，所述一次颗粒形貌的无机颗粒的Dv50为0.5μm-1μm。由此，可以提升电池的动力学性能。
需要说明的是，一次颗粒及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。一次颗粒和二次颗粒可以通过扫描电子显微镜(SEM)图像容易地区分。
在一些实施方式中，本申请隔离膜中，所述复合颗粒包括第二团聚体，所述第二团聚体包括至少两个所述聚丙烯酸酯颗粒。由此，使复合颗粒不至于太软，从而确保电池在膨胀或者比较大的外力下，复合颗粒与极片以及复合颗粒与隔离膜基材间作用合适，从而提高电池动力学性能。进一步地，所述第二团聚体的Dv50为0.3μm-5μm，例如0.5μm-5μm，0.7μm-4.5μm，1μm-4μm，1.3μm-3.5μm，1.5μm-3.2μm，1.7μm-3μm，2μm-2.8μm，2μm-2.5μm，5μm-10μm，5μm-9μm，5μm-8μm，5μm-7μm，5μm-6μm等。在另一些实施方式中，所述第 二团聚体的Dv50为1m-2μm。
在一些实施方式中，本申请的复合颗粒中，所述聚丙烯酸酯颗粒包括一次颗粒形貌的聚丙烯酸酯颗粒和/或二次颗粒形貌的聚丙烯酸酯颗粒，其中所述一次颗粒形貌的聚丙烯酸酯颗粒的Dv50为50nm-400nm，例如50nm-375nm，75nm-375nm，100nm-350nm，125nm-325nm，150nm-300nm，175nm-275nm，200nm-250nm，200nm-225nm等。在另一些实施方式中，所述一次颗粒形貌的聚丙烯酸酯颗粒的Dv50为100nm-200nm。所述二次颗粒形貌的聚丙烯酸酯颗粒的Dv50为2μm-15μm，例如3μm-15μm，4μm-12μm，5μm-10μm，5μm-8μm，5μm-7μm，5μm-6μm等。
在一些实施方式中，所述复合颗粒中所述无机颗粒的含量为1wt％-50wt％，例如1wt％-48wt％，1wt％-45wt％，1wt％-40wt％，1wt％-35wt％，1wt％-30wt％，1wt％-25wt％，1wt％-20wt％，1wt％-15wt％，2wt％-15wt％，3wt％-15wt％，4wt％-15wt％，5wt％-15wt％，7wt％-15wt％，10wt％-15wt％，12wt％-15wt％等。由此，复合颗粒中无机颗粒的含量控制在上述含量范围内，一方面，使得聚丙烯酸酯颗粒之间不会因造粒过程的高温处理发生粘合，提高隔离膜的导离子能力；再一方面，使得隔离膜具有合适的压缩模量，可以确保电池模组在受力状态下隔离膜涂层与阳极之间有合适的作用力。
在一些实施方式中，所述聚丙烯酸酯颗粒的玻璃化转变温度为20℃-80℃，例如25℃-75℃，30℃-70℃，35℃-65℃，40℃-60℃，45℃-55℃，45℃-50℃，由此，采用满足该玻璃化转变温度的聚丙烯酸酯颗粒，可以避免复合颗粒在高温造粒过程中的粘合，提高隔离膜导离子能力。在另一些实施方式中，所述聚丙烯酸酯颗粒的玻璃化转变温度为25℃-65℃。
在一些实施方式中，本申请隔离膜涂层表面形成凸起且该凸起的双面高度为15μm-60μm，例如15μm-58μm，16μm-56μm，18μm-55μm，20μm-52μm，22μm-40μm，25μm-40μm，25μm-38μm，25μm-36μm，28μm-35μm，30μm-32μm等。由此，该高度范围的凸起一方面可以提供隔离膜与极片之间适当空间以释放应力，防止极片卷绕过程断裂，提高安全性；再一方面，使隔离膜和极片之间留有合适空隙，以利于电解液流动和浸润，改善电芯的动力学性能。进一步地，凸起的表面具有第一团聚体。由此，该凸起可以提供隔离膜与极片之间合适的粘接性，从而提升电池的动力学性能。
具体的，基材两个相对表面均形成压敏涂层，两侧压敏涂层上凸起高度之和即为凸起的双面高度，并且凸起的双面高度的测试方法包括：参考图1，首先将负极极片、隔离膜和正极极片依次叠置为电芯后收卷(电芯最外层以正极极片凸面收尾)，然后采用CT设备(ZEISS-1500)对卷绕电芯拐角处负极极片边缘往下距离15±1mm位置进行扫描，在所得CT图中沿水平&斜角(30-45°)取样，有最大间隙的方向划线；内5折取样位置为最内层正极极片凸面至第5层正极极片凸面，取4折均值；6折后取样位置为内层正极极片凸面至外层正极极片凸面，每5折取值。
内5层间隙均值＝[CT测量距离-4*冷压后负极极片厚度*(1+负极极片反弹率)-4*冷压后正极极片厚度(1+正极极片反弹率)-8*隔离膜厚度]/8
内6-10层之后间隙均值＝[CT测量距离-5*冷压后负极极片厚度*(1+负极极片反弹率)-5*冷压后正极极片厚度(1+正极极片反弹率)-10*隔离膜厚度]/10
其中，负极极片反弹率＝(入壳体前负极极片厚度-冷压负极后极片厚度)/冷压后负极极片厚度；
正极极片反弹率＝(入壳体前正极极片厚度-冷压后正极极片厚度)/冷压后正极极片厚度；
隔离膜凸起双面高度＝(内5层间隙均值+内6-10层之后间隙均值)/2。
在一些实施方式中，所述压敏涂层还包括4-20重量份的压力敏感型粘接剂聚合物，例如5-18重量份，7-16重量份，9-15重量份，11-15重量份，并且所述压力敏感型粘接剂聚合物包括粘接剂聚合物和第二增塑剂。粘接剂聚合物和第二增塑剂两者共同作用可使得压 力敏感型粘接剂聚合物具有良好的压敏特性，进一步使得隔离膜具有良好的压敏特性，进一步使得隔离膜具有良好的压敏特性，使其在≤1MPa作用下粘接力在0.1N/m以下，因此可以避免隔离膜在收卷及存储过程中的层与层之间的粘接，以及使其在≥2MPa压力作用下能够与极片发生明显的粘接作用，因此在使用该隔离膜制备电芯时，在常温条件、适当压力下即可将极片与隔离膜紧密贴合，一方面可以避免极片和隔离膜之间发生错位而造成电芯报废、影响电芯性能和产生安全风险，另一方面可以省略传统的电芯生产工艺中的隧道炉及第二道复合工艺，进而可以节约生产空间和生产时间，并降低能耗，明显提升电芯生产的产能，同时可以提升电芯整形性能、安全性能和动力学性能，进而提升包含该电芯的二次电池，以及包含该二次电池的用电装置的安全性能和动力学性能。
在一些实施方式中，所述压力敏感型粘接剂聚合物中包括的粘接剂聚合物和第二增塑剂的质量比可为(4-19)：1，例如(4-18)：1，(4-15)：1，(4-12)：1，(4-11)：1，(4-10)：1，(4-8)：1，(4-6)：1。压力敏感型粘接剂聚合物中包括的第二增塑剂的相对含量在上述范围内，能够保证极片与隔离膜获得较大的粘接力，并且不会导致隔离膜的电阻增加，二次电池的循环性能下降。
其中，第二增塑剂含量可以采用日本岛津株式会社的仪器型号STA449F3热重分析仪。作为具体的示例，测试方法如下：取约10mg压力敏感型粘接剂聚合物固体，原始质量记为M0，升温至200℃，质量记为M1，增塑剂的含量即为M0-M1，粘接剂聚合物的含量为M0-(M0-M1)。测试条件设置为：温度范围-100-400℃，氮气氛围，10℃/min。
在一些实施方式中，所述压力敏感型粘接剂聚合物可为核壳结构，在该核壳结构的内核和外壳中均可包括粘接剂聚合物和第二增塑剂，其中在内核结构中所述粘接剂聚合物和第二增塑剂的质量比可为(2-5)：1，例如(3-4)：1，在外壳结构中所述粘接剂聚合物和第二增塑剂的质量比可为(6-10)：1，例如(7-9)：1，(7-8)：1。核壳结构的内核与外壳都是由粘接剂聚合物和第二增塑剂组成，可以进一步提高压力敏感型粘接剂聚合物的压敏性能，从而进一步提升隔离膜的动力学性能。另一方面，在压力敏感型粘接剂聚合物中包含第二增塑剂，在一定的压力作用下(例如1MPa-2MPa下)，第二增塑剂可以快速迁移到粘接剂聚合物和隔离膜主材料之间，增塑粘接剂聚合物，使其分子链舒展，与负极极片中的例如SBR类粘接剂、CMC的增稠剂、正极极片中的粘接剂例如PVDF发生分子间氢键作用并提升界面润湿，增强两个界面间的铆合作用。在≥2MPa作用下核结构被压碎，核中的第二增塑剂释放，可以进一步提升以上作用。
在一些实施方式中，一部分所述第二增塑剂接枝在所述粘接剂聚合物上。例如基于所述增塑剂的重量，至少5wt％的第二增塑剂接枝在所述粘接剂聚合物上。当一部分所述第二增塑剂接枝在所述粘接剂聚合物上时，能够防止第二增塑剂在循环过程中大量迁移到电解液中，消耗电解液的多种功能添加剂，增加隔离膜电阻值，影响电芯的动力学性能。其中当至少5wt％的第二增塑剂接枝在粘接剂聚合物主链时，隔离膜和极片可以形成“藕断丝连”的作用，进而可以提升常温粘合的持久性，降低反弹，同时可进一步保证不会有过多第二增塑剂在循环过程迁移到电解液，影响电芯性能。其中接枝率可以通过红外测试方法检测，具体为：对粘接剂聚合物、第二增塑剂、压力敏感型粘接剂聚合物各测试获得其傅里叶红外谱图，在压力敏感型粘接剂聚合物1500cm-1-1700cm-1的位置出现一个有别于粘接剂聚合物和单独的第二增塑剂的峰，该峰即表示接枝的第二增塑剂，峰下面积表示接枝的第二增塑剂的量，由此可计算获得第二增塑剂的接枝率。
在一些实施方式中，所述粘接剂聚合物的平均粒径可为0.5μm-3.0μm，例如0.8μm-2.8μm，1μm-2.5μm，1.2μm-2.3μm，1.5μm-2μm，1.8μm-2μm。满足本申请平均粒径的粘接剂聚合物有助于压力敏感型粘接剂聚合物在复合颗粒上均匀分布，有助于在一定压力下其内核和外壳与极片粘接的发挥。在一些实施方式中，所述压力敏感型粘接剂聚合物的平均粒径可为0.8μm-2μm。
其中，压力敏感型粘接剂聚合物的平均粒径可以参照标准GB/T 19077.1-2016，使用激 光粒度分析仪(如Malvern Master Size 3000)测定。
在一些实施例中，所述压力敏感型粘接剂聚合物的DSC熔点可为-50℃-100℃，例如-45℃-95℃，-40℃-90℃，-35℃-85℃，-30℃-80℃，-25℃-75℃，-20℃-70℃，-15℃-65℃，-10℃-60℃，-5℃-55℃，0℃-50℃，5℃-45℃，10℃-40℃，15℃-35℃，20℃-30℃，25℃-30℃。由此，满足上述DSC熔点的压力敏感型粘接剂聚合物，能够保证在常温下的粘结力，避免在1MPa下粘接力过大造成隔离膜收卷粘接；同时避免在常温2MPa下粘接力过小造成隔离膜与极片粘接较弱，不利于电芯整形。
根据一些实例，DSC熔点为本领域公知的含义，可以用本领域公知的仪器及方法进行测定，例如，可以是通过德国NETZSC公司的仪器型号为DSC 200F3的DSC熔点测试仪。作为具体的示例，测试方法如下：取约10mg样品进行测试。测试条件设置为：温度范围：-100-200℃，氮气氛围，10℃/min。选取第一次升温时，吸收峰所对应的温度即为相应的DSC熔点。
在一些实施方式中，所述粘接剂聚合物包括以下的第一单体中的至少一种、第二单体中的至少一种、第三单体中的至少一种和反应型分散剂中的至少一种的反应单体混合物共聚形成的共聚物：
第一单体：其熔点一般高于80℃，包括丙烯酸、甲基丙烯酸、甲基丙烯酸甲酯、甲基丙烯酸叔丁酯、甲基丙烯酸异冰片酯、羟甲基丙烯酰胺、丙烯酰胺、苯乙烯、丙烯腈；
第二单体：其熔点一般不超过80℃，包括丙烯酸C4-C22烷基酯、丙烯酸异丁酯、丙烯酸异辛酯、丙烯酸叔丁酯、丙烯酸-2-乙基己酯(异辛酯)、丙烯酸环己酯、甲基丙烯酸乙酯、甲基丙烯酸异丁酯、甲基丙烯酸-2-乙基己酯、甲基丙烯酸正己酯、甲基丙烯酸环己酯、甲基丙烯酸苄酯、丙烯酸-2-羟乙酯、丙烯酸-2-羟丙酯、甲基丙烯酸亚乙基脲乙酯、甲基丙烯酸双环戊烯乙氧基酯、甲基丙烯酸四氢呋喃酯、甲基丙烯酸三氟乙酯、甲基丙烯酸二甲氨基乙酯、甲基丙烯酸二乙氨基乙酯、甲基丙烯酸亚乙基脲乙酯、甲基丙烯酸丙烯酯、甲基丙烯酸双环戊烯乙氧基酯、甲基丙烯酸四氢呋喃酯、甲基丙烯酸三氟乙酯；
第三单体：包括甲基丙烯酸-2-羟乙酯、甲基丙烯酸-2-羟丙酯、丙烯酸缩水甘油酯、甲基丙烯酸缩水甘油酯、甲基丙烯酸二甲氨基乙酯、甲基丙烯酸二乙氨基乙酯、乙烯基三甲氧基硅烷、乙烯基三乙氧基硅烷、乙烯基三异丙氧基硅烷、3-甲基丙烯酰氧基丙基三甲氧基硅烷、N-羟甲基丙烯酰胺、N-丁氧甲基(甲基)丙烯酰胺、二丙酮丙烯酰胺、甲基丙烯酸乙酰乙酸乙酯、二乙烯基苯、环氧值在0.35-0.50的环氧树脂、二乙烯苯；
反应型分散剂：包括聚乙烯醇、聚丙烯醇、聚丙烯乙二醇、聚乙二醇、聚乙烯酸醇。可选地，这些反应型分散剂的醇解度≥85％，平均聚合度400-2000；优选醇解度≥88％，平均聚合度500-1600。
由此，该组成的粘接剂聚合物具有适合的溶胀、压敏性和粘接性能，同时具有合适的弹性模量，从而使得电芯具有优异的整形效果、动力学性能和安全性能。
需要说明的是，在本申请中，术语“醇解度”是指醇解之后得到的产品中羟基占原有基团的百分比，单位为摩尔分数％。例如原有基团(酯基)有100个，醇解后羟基是60个，则醇解度为60％。
需要说明的是，在本申请中，术语“平均聚合度”是指聚合物由聚合度不等的同系聚合物分子组成，其聚合度具有统计平均意义。最常用的表示平均聚合度的方法有两种：按分子数平均而得的聚合度，称为数均聚合度；按重量平均而得的聚合度，称为重均聚合度。本申请中所述“平均聚合度”为数均聚合度。
在一些实施方式中，所述第二增塑剂可以包括甘油C4-C10烷基二醚或者单醚、甘油C4-C10羧酸单酯或者二酯、丙二醇C4-C10烷基单醚和甘油中的至少之一。
在一些实施例中，压力敏感型粘接剂聚合物可以按照以下合成方法合成，包括以下步骤：
第一步，在溶剂(例如去离子水)中，依次加入0.1质量％-1质量％(其相对于在合成 压力敏感型粘接剂聚合物时加入的反应单体混合物(包含第一单体、第二单体、第三单体和反应型分散剂)、助剂(包括乳化剂、稳定剂、水性引发剂)和第二增塑剂的总重量，下同)的乳化剂(例如烯丙基磺酸盐)，2质量％-3质量％、数均分子量≤1000，熔点在0℃-30℃的低聚物(例如甲基丙烯酸十八烷基酯)，均质机转速控制在8000r/min-12000r/min，如10000r/min进行分散，分散时间可为20min-60min，如50min，分散反应温度为20℃-40℃，如25℃，获得第一混合液。
第二步，向第一混合液中加入1质量％-4质量％的稳定剂，如包括聚氧化乙烯、烯丙基聚醚硫酸盐、亚甲基丁二酸(衣康酸)、苯乙烯磺酸、乙烯基磺酸钠和纳米纤维素钠中的至少一种；均质机转速控制在6000r/min-8000r/min，比如6500r/min进行混合，时间为20min-60min，如30min，混合反应温度为20℃-60℃，如45℃，获得第二混合液。
第三步，向第二混合液中加入0.05质量％-0.5质量％的水性引发剂，如包括碳酸氢钠、过氧化苯甲酰、过氧化月桂酰、异丙苯过氧化氢、叔丁基过氧化氢、过氧化二叔丁基、过氧化二异丙苯、过氧化苯甲酸叔丁酯、过氧化叔戊酸叔丁基酯、过氧化甲乙酮、过氧化环己酮过氧化二碳酸二异丙酯、过氧化二碳酸二环己酯、过硫酸钾、过硫酸钠、过硫酸铵、偶氮二异丁腈和偶氮二异庚腈中的至少一种。均质机转速控制在8000r/min-12000r/min，比如8000r/min进行混合，时间20min-60min，如30min。反应温度60℃-80℃，如72℃，获得第三混合液。
第四步，在均质机转速为100r/min-1000r/min，如400r/min的条件下，逐步向第三混合液中均匀滴加(控制在60min刚好滴完)35质量％-45质量％的反应单体混合物，反应时间80min-100min，如80min，获得第四混合物。
第五步，将第四混合物在反应温度为80℃-90℃，如84℃；均质机转速为12000r/min-18000r/min，如15000r/min的条件下继续反应，时间为120min-240min，如180min，获得第五混合物。
第六步，向第五混合物中加入10质量％-20质量％的第二增塑剂，如甘油，反应温度控制为80℃-90℃，如84℃；均质机转速控制为12000r/min-18000r/min，如15000r/min，反应时间为120min-240min，如180min，获得第六混合物。
第七步，向第六混合物中加入0.05质量％-0.5质量％的水性引发剂，如过硫酸铵-碳酸氢钠。均质机转速控制为8000r/min-12000r/min，如8000r/min，时间为20-60min，如30min。反应温度为60℃-80℃，如72℃，获得第七混合物。
第八步，在均质机转速为100r/min-1000r/min，如400r/min的条件下，向第七混合物中逐步均匀滴加(控制在60min刚好滴完)30质量％-40质量％的反应单体混合物，反应时间为100min-160min，如120min，获得第八混合物。
第九步，向第八混合物中加入5质量％-20质量％的第二增塑剂，如甘油，控制反应温度为80℃-90℃，如84℃；均质机转速为12000r/min-18000r/min，如15000r/min，时间为120min-240min，如180min，获得第九混合物。
第十步，将第九混合物的温度降至50℃以下，过滤出料，即得核壳结构的压力敏感型粘接剂聚合物。本领域技术人员也可以参照上述方法(省略第七至第九步，并相应改变添加的第二增塑剂和反应单体混合物的质量分数)合成获得非核壳结构的压力敏感型粘接剂聚合物。
在一些实施方式中，所述压敏涂层的平均厚度为2μm-20μm，例如4μm-18μm，5μm-15μm，7μm-12μm，10μm-12μm。由此，适当压力下即可将极片与隔离膜紧密贴合，提高电芯的动力学性能。在一些实施方式中，所述压敏涂层的平均厚度为2μm-15μm。
在一些实施方式中，本申请隔离膜涂层中还可以包括有机颗粒，其中，所述有机颗粒包括聚四氟乙烯颗粒、聚三氟氯乙烯颗粒、聚氟乙烯颗粒、聚偏二氟乙烯颗粒、聚乙烯颗粒、聚丙烯颗粒、聚丙烯腈颗粒、聚环氧乙烷颗粒、含氟烯基单体单元与乙烯基单体单元的共聚物颗粒、含氟烯基单体单元与丙烯酸类单体单元的共聚物颗粒、含氟烯基单体单元 与丙烯酸酯类单体单元的共聚物颗粒，以及上述各均聚物或共聚物的改性化合物颗粒中的至少之一，所述复合颗粒和所述有机颗粒在所述压敏涂层表面形成所述凸起。由此，可以提高电池的循环性能和安全性能。
在一些实施方式中，本申请隔离膜涂层的有机颗粒形成第三团聚体。其中，所述第三团聚体的Dv50为5μm-30μm，例如5μm-28μm，5μm-25μm，5μm-22μm，5μm-20μm，5μm-20μm，5μm-18μm，5μm-15μm，5μm-12μm，5μm-10μm，5μm-8μm，5μm-6μm等。
在一些实施方式中，所述第三团聚体中包括一次颗粒形貌的有机颗粒，并且相邻两个所述有机颗粒之间具有间隙。该间隙可以作为离子传输通道，从而提高隔离膜的离子电导率。在一些实施方式中，所述一次颗粒形貌的有机颗粒的Dv50为50nm-400nm，例如50nm-375nm，75nm-375nm，100nm-350nm，125nm-325nm，150nm-300nm，175nm-275nm，200nm-250nm，200nm-225nm等，在另一些实施方式中，所述一次颗粒形貌的有机颗粒的Dv50为100nm-200nm。
本申请中，Dv50是指累计体积分布百分数达到50％时所对应的粒径，Dv10是指累计体积分布百分数达到10％时所对应的粒径。在本申请中，复合颗粒的Dv10、复合颗粒的Dv50均可采用激光衍射粒度分析法测定。例如参照标准GB/T 19077-2016，使用激光粒度分析仪(例如Malvern Master Size 3000)进行测定。一次颗粒形貌的无机颗粒的Dv50、一次颗粒形貌的聚丙烯酸酯颗粒的Dv50、二次颗粒形貌的聚丙烯酸酯颗粒的Dv50可以采用可以从隔离膜SEM图中统计得出，例如取10Kx的放大倍数的隔离膜SEM图，每个样品使用5个平行样，每个平行样使用10个位置，每个位置选取20个点统计，最后取平均值即为对应粒径。第一团聚体的Dv50、第二团聚体的Dv50以及第三团聚体的Dv50可以使用所述隔离膜的CP图统计得出，例如取5Kx的放大倍数的隔离膜CP图，每个样品使用5个平行样，每个平行样使用10个位置，每个位置选取20个点统计，最后取平均值即为对应粒径。
在一些实施方式中，所述复合颗粒与有机颗粒的质量比为(20～90)：(0～70)，例如所述复合颗粒与所述聚偏氟乙烯颗粒的质量比为(20～90)：(5～65)，(20～90)：(10～60)，(20～90)：(20～50)，(20～90)：(30～40)，(30～80)：(0～70)，(40～70)：(0～70)，(50～60)：(0～70)，(30～80)：(5～65)，(40～65)：(10～55)，(45～60)：(20～45)，(55～60)：(30～45)。由此，可以提高电解液的浸润性及分布均匀性，改善电池的高温存储性能，提升电池安全性能和循环性能。在另一些实施方式中，所述复合颗粒与所述有机颗粒的质量比为(45～90)：(0～45)。由此，可以提升电池安全性能和循环性能。
如图2所示，所述隔离膜包括基材和压敏涂层(未示出)，所述压敏涂层中包括复合颗粒、有机颗粒、第一增塑剂、乳化剂和粘接剂，所述第一增塑剂和乳化剂均匀分布于所述复合颗粒内部及间隙间，所述复合颗粒和有机颗粒通过粘接剂与基材相连，所述复合颗粒和所述有机颗粒在所述压敏涂层表面形成凸起。
在一些实施方式中，所述压敏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、分散剂、润湿剂以及其他种类的粘接剂等。上述其他有机化合物在压敏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。
本申请中，基材是具有良好的化学稳定性和机械稳定性的多孔结构的膜材料。在一些实施方式中，基材可以是单层膜材料，也可以是多层复合膜材料。在基材为多层复合膜材料时，各层的材料可以相同或不同。
在一些实施方式中，本申请的隔离膜中，所述基材可为包含以下的一种或多种的多孔膜或多孔非织造网：聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚酯、聚缩醛、聚酰胺、聚碳酸酯、聚酰亚胺、聚醚醚酮、聚芳基醚酮、聚醚酰亚胺、聚酰胺酰亚胺、聚苯并咪唑、聚醚砜、聚苯醚、环烯烃共聚物、聚苯硫醚和聚乙烯萘。在另一些实施方式中，所述基材为包含聚乙烯和/或聚丙烯的多孔膜或多孔非织造网。通过选择 上述基材来制备隔离膜，有利于基材通过粘接剂与涂层结合，形成适度致密、多孔且可导锂离子的隔离膜。
在一些实施方式中，本申请的隔离膜中，所述基材具有10％至95％，可选地35％至45％的孔隙率。由此，可以在提高隔离膜的导离子性能的同时，降低正极、负极极片发生接触的概率。在一些实施方式中，本申请的隔离膜中，所述基材具有0.1μm至50μm，可选地0.1μm至5μm的孔直径。选择具有上述孔隙结构的基材，使隔离膜具有良好的导离子性能，降低正、负极极片发生直接接触的概率，进而提升电芯动力学和安全性能。
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-10μm。所述基材的厚度控制在所给范围内时，可以在确保电池循环性能和安全性能的前提下，进一步提高电池能量密度。
在一些实施方式中，压敏涂层的剥离力为40N/m以上；隔离膜在无夹持状态下于150℃环境中放置1小时后，其在纵向(MD)或横向(TD)上的热收缩率均在5％以下；200℃热枪破坏尺寸为0；隔离膜与极片的粘接力为1.0N/m以上，25℃下的隔膜电阻在2欧姆以下。
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/T36363-2018进行测试。
根据一些实施例，聚丙烯酸酯颗粒、酯类化合物、乳化剂、压力敏感型粘接剂聚合物和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，从而确定材料种类。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。
本申请第二方面还提供一种制备隔离膜的方法，包括如下步骤：
(1)提供基材；
(2)在基材的至少部分表面上形成压敏涂层，所述压敏涂层包括聚丙烯酸酯颗粒和第一增塑剂，所述复合颗粒在所述压敏涂层表面形成凸起，所述复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，至少两个所述聚丙烯酸酯颗粒之间具有所述无机颗粒，所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2。
具体的，基材、第一增塑剂和复合颗粒同于上文描述，此处不再赘述。
在一些实施方式中，隔离膜包括基材和压敏涂层，所述压敏涂层设置在所述基材的仅一个表面上。
在一些实施方式中，隔离膜包括基材和压敏涂层，所述压敏涂层同时设置在所述基材的两个表面上。
在一些实施方式中，步骤(2)可以采用下列步骤进行：(2-1)提供压敏涂层浆料，所述压敏涂层浆料包括复合颗粒和第一增塑剂；(2-2)将所述压敏涂层浆料涂布在所述基材的至少一侧上并干燥，得到所述隔离膜。
在一些实施方式中，在步骤(2-1)，所述压敏涂层浆料中的溶剂可以为水，例如去离子水。
在一些实施方式中，在步骤(2-1)，所述压敏涂层浆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、乳液状的粘接剂。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(2-1)，所述压敏涂层浆料的固含量可以控制在10％-20％，例如，可以为12％-15％，基于重量计。当压敏涂层浆料的固含量在上述范围内时，可以提升涂层制造优率及提升涂层粘接性能。
在一些实施方式中，在步骤(2-1)，所述第一增塑剂包括酯类化合物，所述酯类化合物的溶解度参数为12MPa1/2-30MPa1/2。
在一些实施方式中，在步骤(2-1)中，所述压敏涂层浆料还可以包括乳化剂，所述乳 化剂包括阴离子乳化剂和非离子型乳化剂中的至少之一。乳化剂的加入可以使得酯类化合物均匀分布的复合颗粒中，进一步提升隔离膜的压敏特性和制作优率。作为示例，阴离子乳化剂包括烷基苯磺酸盐；非离子型乳化剂包括脂肪醇聚氧乙烯醚、烷基酚聚氧乙烯醚、脂肪酸聚氧乙烯醚、甘油酯类、聚甘油硬脂酸酯的一种或几种。
在一些实施方式中，在步骤(2-1)中，所述压敏涂层浆料还包括压力敏感型粘接剂聚合物，并且所述压力敏感型粘接剂聚合物包括粘接剂聚合物和第二增塑剂。粘接剂聚合物和第二增塑剂两者共同作用可使得压力敏感型粘接剂聚合物具有良好的压敏特性，进一步使得隔离膜具有良好的压敏特性，，进一步使得隔离膜具有良好的压敏特性，使其在≤1MPa作用下粘接力在0.1N/m以下，因此可以避免隔离膜在收卷及存储过程中的层与层之间的粘接，以及使其在≥2MPa压力作用下能够与极片发生明显的粘接作用，因此在使用该隔离膜制备电芯时，在常温条件、适当压力下即可将极片与隔离膜紧密贴合，一方面可以避免极片和隔离膜之间发生错位而造成电芯报废、影响电芯性能和产生安全风险，另一方面可以省略传统的电芯生产工艺中的隧道炉及第二道复合工艺，进而可以节约生产空间和生产时间，并降低能耗，明显提升电芯生产的产能，同时可以提升电芯整形性能、安全性能和动力学性能，进而提升包含该电芯的二次电池，以及包含该二次电池的用电装置的安全性能和动力学性能。
在一些实施方式中，所述压敏涂层浆料还包括有机颗粒，所述有机颗粒包括聚四氟乙烯颗粒、聚三氟氯乙烯颗粒、聚氟乙烯颗粒、聚偏二氟乙烯颗粒、聚乙烯颗粒、聚丙烯颗粒、聚丙烯腈颗粒、聚环氧乙烷颗粒、含氟烯基单体单元与乙烯基单体单元的共聚物颗粒、含氟烯基单体单元与丙烯酸类单体单元的共聚物颗粒、含氟烯基单体单元与丙烯酸酯类单体单元的共聚物颗粒，以及上述各均聚物或共聚物的改性化合物颗粒中的至少之一。
在一些实施方式中，在步骤(2-2)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(2-2)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。
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。
上述基材、复合颗粒、酯类化合物、乳化剂、有机颗粒、压力敏感型粘接剂聚合物和有机颗粒均可以通过市购获得。
本申请第三方面提供了一种电池，其包括上述第一方面的隔离膜或采用第二方面制备的隔离膜。
电池，是指在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，电池包括正极极片、负极极片、隔离膜及电解质。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。电解质在正极极片和负极极片之间起到传导离子的作用。
[正极极片]
在电池中，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。
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接剂、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，粘接剂可以为丁苯橡胶(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接剂、导电剂和其他可选助剂。
作为示例，导电剂可以包括超导碳、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，粘接剂可以包括丁苯橡胶(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剂及分散剂(例如羧甲基纤维素钠CMC-Na)、PTC热敏电阻材料。
[电解液]
电池可以包括电解液，电解液在正极和负极之间起到传导离子的作用。所述电解液可以包括电解质盐和溶剂。
作为示例，电解质盐可包括六氟磷酸锂(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，所述溶剂可包括碳酸亚乙酯(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。
在一些实施方式中，电池可以为锂离子二次电池。
本申请实施例对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3是作为一个示例的方形结构的电池1。
在一些实施方式中，电池可包括外包装。该外包装用于封装正极极片、负极极片和电解质。
在一些实施方式中，外包装可包括壳体和盖板。其中，壳体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。壳体具有与容纳腔连通的开口，盖板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。电极组件封装于所述容纳腔。电解质可采用电解液，电解液浸润于电极组件中。电池所含电极组件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，电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳。
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)中的一种或几种。
在一些实施方式中，电池可以组装成电池模块，电池模块所含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4是作为一个示例的电池模块2。参照图4，在电池模块2中，多个电池1可以是沿电池模块2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电池1进行固定。
电池模块2还可以包括具有容纳空间的外壳，多个二次电池1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，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5和6是作为一个示例的电池包3。参照图5和6，在电池包3中可以包括电池箱和设置于电池箱中的多个电池模块2。电池箱包括上箱体4和下箱体5，上箱体4能够盖设于下箱体5，并形成用于容纳电池模块2的封闭空间。多个电池模块2可以按照任意的方式排布于电池箱中。
[用电装置]
本申请还提供一种用电装置，所述用电装置包括所述的电池，所述电池用于提供电能。具体的，所述电池可以作为所述用电装置的电源，也可以作为所述用电装置的能量存储单元。所述用电装置可以但不限于是移动设备(例如手机、笔记本电脑)、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)、电气列车、船舶及卫星、储能系统。
图7是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑。该用电装置通常要求轻薄化，可以采用电池作为电源。
为了使本申请实施例所解决的技术问题、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。
一、隔离膜的制备
(1)提供PE基材，其厚度为9μm、孔径为50nm且孔隙率为38％。
(2)配制涂层浆料：将复合颗粒、第一增塑剂、乳化剂、压力敏感型粘接剂聚合物(其玻璃化转变温度约为10℃，平均粒径为1.1μm，包括质量比为5:1的粘接剂聚合物和第二增塑剂(其中相对于第二增塑剂的重量，8wt％的第二增塑剂接枝在粘接剂聚合物上)以及若干去离子水，其中粘接剂聚合物为30wt％丙烯酸异丁酯+25wt％丙烯酸异辛酯+5wt％丙烯酸-2-羟丙酯+15wt％苯乙烯+22wt％丙烯酰胺+3％聚乙二醇共聚物，第二增塑剂为甘油)、有机颗粒、分散剂(BYK-22136)在适量的溶剂去离子水中混合均匀，得到固含量为12％(按重量计)的压敏涂层浆料；
(3)将步骤(2)配制的压敏涂层浆料用涂布机涂布在PE基材的2个表面上后进行干燥，即得隔离膜1，并且该隔离膜单侧压敏涂层的厚度为3μm。
其中上述复合颗粒采用下列步骤制备得到：
a、在室温下，按照重量百分比丙烯酸-2-羟基乙酯10wt％、丙烯酸正丁酯66wt％、甲基丙烯酸甲酯8wt％、三羟甲基丙烷三丙烯酸酯1wt％、丙烯腈10wt％和丙烯酰胺5wt％的比例将所需单体搅拌混合均匀，得到混合单体；
b、向装有机械搅拌装置、温度计和冷凝管的10L四口烧瓶中加入2kg混合单体，60g十二烷基硫酸钠乳化剂，20g过硫酸铵引发剂和2.40kg去离子水，以1600rpm的转速搅拌乳化30min，然后在氮气保护下升温至75℃，反应4h后，使用浓度为1wt％的NaOH水溶液调节pH＝6.5，立即降温至40℃以下出料，即得乳液状态的有机聚合物，其固含量约45wt％；
c、将上述有机聚合物干重与氧化硅按照质量比为9：1的比例加入到适量的去离子水中，搅拌1h充分混合后，经喷雾干燥除去溶剂，制得粉末。然后经研磨粉碎，得到Dv50为5μm的复合颗粒。
实施例中所用的材料均可以通过商购获得。例如：
无机颗粒可以购于安徽壹石通科技股份有限公司；
有机颗粒可以购自乳源东阳光氟树脂有限公司；
基材可以购于上海恩捷新材料有限公司。
分散剂可以购自常熟威怡科技有限公司。
润湿剂可以购自陶氏化学公司。
第一增塑剂可以购自亨斯迈公司。
乳化剂可以购自巴斯夫公司。
压力敏感型粘接剂聚合物可以购自茵地乐科技集团有限公司。
隔离膜1-63的制备工艺中对应参数如表1-7所示。




















二、电池的制备
实施例1
1、正极极片的制备
将正极活性材料LiNi1/3Mn1/3Co1/3O2、导电剂乙炔黑、粘接剂聚偏二氟乙烯(PVDF)按质量比94：3：3在溶剂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、裁切工序，得到正极极片。正极极片上正极活性材料的负载量为0.32g/1540.25mm2，密度为3.45g/cm3。
2、负极极片的制备
将活性物质人造石墨、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂碳甲基纤维素钠(CMC)按照重量比95:2:2:1在溶剂去离子水中充分搅拌混合均匀后，得到负极浆料，将该浆料涂覆于负极集流体Cu箔上烘干、冷压，得到负极极片。负极极片上石墨的负载量为0.18g/1540.25mm2，密度为1.65g/cm3。
3、隔离膜
隔离膜采用上述制备的隔离膜1。
4、电解液的制备
将碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按体积比3:5:2混合，然后将LiPF6均匀溶解在上述溶液中，得到电解液。该电解液中，LiPF6的浓度为1mol/L。
5、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、整形工序，获得二次电池。
实施例2-60以及对比例1-3的二次电池与实施例1的电池的制备方法相似，不同点在于使用了不同的隔离膜，实施例2-60的二次电池采用隔离膜2-60，对比例1-3的二次电池采用隔离膜61-63。
三、隔离膜与正极极片或负极极片间粘接性能评估
测试过程如下：
1、选取长为300mm宽为100mm的上述隔离膜以及上述制备的正极极片和负极极片。
2、将隔离膜上下用纸张包好使用刀模和冲压机冲切成54.2mm*72.5mm的样品。
3、将冲切好的隔离膜样品与正极极片或负极极片整齐叠好，注意隔离膜朝上，上下各垫130mm*130mm大小铁氟龙，把叠好的样品放置在硬纸板的中间，盖上一张150mm*160mm硬纸板。
4、将叠好的样品放入平压机调整压力，调整好气压，压力＝1150KG±10KG(相当于约3MPa)或压力＝2650Kg±10KG(相当于约7MPa)，设定T＝25℃或95℃，时间设定为10s，进行热压。
5、将热压好的样品使用刀模和冲压机冲切成72.5mm*15mm的小条。
6、将极片的一面通过双面胶贴在钢板上固定，另一面粘接有隔离膜，使用双面胶将宽度为15mm的A4纸条与隔离膜粘连在一起，完成测试样品制作。测试时，将固定极片的钢板固定，而拉力机向上拉动A4纸条，使隔离膜与极片剖离。
7、开启高铁拉力机，依次设置为：粘接力测试、速度50mm/min，起始夹具间距40mm。
8、将测试样品置于夹具之间，将钢板的末端固定在下夹头，将A4纸固定在上夹头。上下端夹头分别用夹具夹紧。
9、点击电脑桌面拉伸的操作界面，将力、位移等清零，然后点击“开始”，进行预拉伸约5mm；预拉伸后，重新将力、位移等清零，开始测试，等测试完后，导出并保存完整数据。
10、每一组至少测量5条测试样品，并且5条测试样品粘接力测试的曲线重复性较好，则进行下一组测试。否则需要再进行测试，直到5条测试样品重复性较好为止。
11、测试完成后，作出粘接强度(N/m)-位移曲线，并计算粘接力大小。
四、隔离膜的电阻性能评估
测试过程如下：
(1)隔离膜准备：将各待测隔离膜裁成相同的大小的样品(45.3mm*33.7mm)，并将样品放置在60℃的环境下烘烤至少4h，然后迅速转入25℃百级洁净手套箱中备用；
(2)对称电池限域性Pocket袋(对称电池限域性铝塑袋(铝塑袋是软包电池用的聚丙烯和铝箔复合的通用商品))制备：采用Cu Foil对Cu Foil(铜箔对铜箔)为集流体组装的空白对称电池。该Pocket袋的限域性是通过绿胶中间冲孔实现的。Pocket袋在使用前需放在60℃的环境下烘烤至少4h，然后迅速转入如上文(1)中所述的25℃百级洁净手套箱中备用；
(3)对称电池的组装：以阳极极片为电极，在如上文(1)中所述的手套箱中原位组装5组分别具有不同隔离膜层数(1、2、3、4、5层)的对称电池样品，每组样品有5个平行样；用简易封装机将Pocket袋侧封，移液枪注液(300μL)，底封；
(4)对组装好的对称电池上夹具：将组装好的对称电池放置在如上文(1)中所述的手套箱中过夜，以便让电解液充分浸润隔离膜；次日，上金属夹具，夹具的压力控制在0.7MPa；
(5)测量电化学阻抗谱(EIS)：
测量之前，将具有不同隔离膜层数的对称电池放在高低温箱中25℃恒温半小时，测量设定温度(25℃)下的EIS(如果是低温(例如-25℃-0℃)，恒温的时间可相应延长，如两个小时左右)；
(6)采用法国Bio-Logic VMP3电化学工作站，电压＜5V，电流＜400mA，电流精度：0.1％*100μA。测量时，EIS的测量条件设置为电压频率1MHz-1kHz，扰动电压设置为5MV，夹具的压力控制在0.7MPa；
(7)以EIS数据的实部对负虚部做出散点图，同时要将不同层数和相同层数的平行样的数据画在一张图上，如此得到的EIS图作为EIS原始数据的比较；
(8)将上述(7)获得的EIS图中非第一象限的点剔除，得到新的EIS图。在所述新的EIS图中对第一象限的散点进行线性拟合，得到关联式，令y＝0，可得到x值，即为所需的电解液在隔离膜中的电阻值。依次类推，则可以将测得的EIS数据进行线性拟合处理即可得到不同层数的平行样之间的电阻值。
五、电池性能评估
循环性能测试：
将制备的电池各组取5支，通过以下步骤对电池重复进行充电和放电，并计算电池在25℃或45℃条件下的循环容量保持率。
在25℃的环境中，将实施例和对比例制备得到的二次电池采用三片钢夹具固定，夹具与电池间有单边隔热垫1mm，施加0.1MPa的预紧力，进行第一次充电和放电，在0.7C(即2h内完全放掉理论容量的电流值)的充电电流下进行恒流和恒压充电，直到上限电压为4.4V，然后在0.5C的放电电流下进行恒流放电，直到最终电压为3V，记录首次循环的放电容量；而后进行1000次的充电和放电循环，记录第1000次循环的放电容量。循环容量保持率＝(第1000次循环的放电容量/首次循环的放电容量)×100％。
在45℃的环境中，将实施例和对比例制备得到的二次电池采用三片钢夹具固定，夹具与电池间有单边隔热垫1mm，施加0.1MPa的预紧力，进行第一次充电和放电，在0.7C(即2h内完全放掉理论容量的电流值)的充电电流下进行恒流和恒压充电，直到上限电压为4.4V，然后在0.5C的放电电流下进行恒流放电，直到最终电压为3V，记录首次循环的放电容量；而后进行1000次的充电和放电循环，记录第1000次循环的放电容量。循环容量保持率＝(第1000次循环的放电容量/首次循环的放电容量)×100％。
表8中给出了测得实施例1-60和对比例1-3的隔离膜和电池性能数据。
表8

由表8可知，在25℃、7MPa下实施例1-60中隔离膜对正极极片的粘接力在0.3N/m-2.3N/m之间；在25℃、7MPa下实施例1-60中隔离膜对负极极片的粘接力在0.1N/m-0.9N/m之间；在95℃、3MPa下实施例1-60中隔离膜对正极极片的粘接力在1N/m-4.8N/m之间；在95℃、3MPa下实施例1-60中隔离膜对负极极片的粘接力在0.4N/m-2.0N/m之间；并且实施例1-60的隔离膜电阻不高于2.5Ω；实施例1-60的电池的循环容量保持率均优于对比例1-3，由此表明采用本申请的隔离膜与极片之间粘接力合适，且电阻较低，从而可以提高电池的动力学性能和安全性能。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (34)

  1. 一种隔离膜，其中，包括：
    基材；
    压敏涂层，所述压敏涂层形成在所述基材的至少部分表面上，所述压敏涂层包括复合颗粒和第一增塑剂，所述复合颗粒在所述压敏涂层表面形成凸起，所述复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，至少两个所述聚丙烯酸酯颗粒之间具有所述无机颗粒，所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2。
  2. 根据权利要求1所述的隔离膜，其中，所述第一增塑剂包括酯类化合物，所述酯类化合物的溶解度参数为12MPa1/2-30MPa1/2。
  3. 根据权利要求2所述的隔离膜，其中，所述压敏涂层还包括乳化剂，所述乳化剂包括阴离子乳化剂和非离子型乳化剂中的至少之一。
  4. 根据权利要求3所述的隔离膜，其中，所述压敏涂层包括80重量份-96重量份的复合颗粒、5重量份-30重量份的酯类化合物和0.1重量份-0.5重量份的乳化剂。
  5. 根据权利要求1-4中任一项所述的隔离膜，其中，所述复合颗粒的Dv50≥2.5μm，优选2.5μm-10μm，更优选3μm-8μm。
  6. 根据权利要求1-5中任一项所述的隔离膜，其中，所述复合颗粒包括第一团聚体，所述第一团聚体包括至少两个所述无机颗粒。
  7. 根据权利要求6所述的隔离膜，其中，0.01μm≤第一团聚体的Dv50≤复合颗粒的Dv10。
  8. 根据权利要求1-7中任一项所述的隔离膜，其中，所述复合颗粒包括一次颗粒形貌的无机颗粒。
  9. 根据权利要求8所述的隔离膜，其中，所述一次颗粒形貌的无机颗粒的Dv50为0.01μm-1μm，优选为0.5μm-1μm。
  10. 根据权利要求1-9中任一项所述的隔离膜，其中，所述复合颗粒包括第二团聚体，所述第二团聚体包括至少两个所述聚丙烯酸酯颗粒。
  11. 根据权利要求10所述的隔离膜，其中，所述第二团聚体的Dv50为0.3μm-5μm，优选为1μm-2μm。
  12. 根据权利要求1-11中任一项所述的隔离膜，其中，所述聚丙烯酸酯颗粒包括一次颗粒形貌的聚丙烯酸酯颗粒和/或二次颗粒形貌的聚丙烯酸酯颗粒。
  13. 根据权利要求12所述的隔离膜，其中，所述一次颗粒形貌的聚丙烯酸酯颗粒的Dv50为50nm-400nm，优选100nm-200nm。
  14. 根据权利要求12所述的隔离膜，其中，所述二次颗粒形貌的聚丙烯酸酯颗粒的Dv50为2μm-15μm，优选5μm-8μm。
  15. 根据权利要求1-14中任一项所述的隔离膜，其中，所述聚丙烯酸酯颗粒的玻璃化转变温度为20℃-80℃，优选为25℃-65℃。
  16. 根据权利要求1-15中任一项所述的隔离膜，其中，所述复合颗粒中所述无机颗粒的含量为1wt％-50wt％，可选为1wt％-40wt％，更可选为2wt％-15wt％，最优选为5wt％-15wt％。
  17. 根据权利要求1-16中任一项所述的隔离膜，其中，所述凸起的双面高度为15μm-60μm。
  18. 根据权利要求1-17中任一项所述的隔离膜，其中，所述压敏涂层还包括4重量份-20重量份的压力敏感型粘接剂聚合物，所述压力敏感型粘接剂聚合物包括粘接剂聚合物和第二增塑剂。
  19. 根据权利要求18所述的隔离膜，其中，所述粘接剂聚合物的平均粒径为0.5μm-3.0μm，可选为0.8μm-2.0μm。
  20. 根据权利要求18或19所述的隔离膜，其中，所述压力敏感型粘接剂聚合物的DSC 熔点为-50℃-100℃，可选为-45℃-60℃。
  21. 根据权利要求18-20中任一项所述的隔离膜，其中，所述粘接剂聚合物与所述第二增塑剂的质量比为(4-19)：1，可选为(4-11)：1。
  22. 根据权利要求18-21中任一项所述的隔离膜，其中，所述压力敏感型粘接剂聚合物为核壳结构，所述核壳结构的内核和外壳均包括粘接剂聚合物和第二增塑剂，
    其中，在内核结构中所述粘接剂聚合物和第二增塑剂的质量比为(2-5)：1，可选为(3-4)：1，
    在外壳结构中所述粘接剂聚合物和第二增塑剂的质量比为(6-10)：1，可选为(7-9)：1。
  23. 根据权利要求18-22中任一项所述的隔离膜，其中，所述粘接剂聚合物包括以下的第一单体中的至少一种、第二单体中的至少一种、第三单体中的至少一种和反应型分散剂中的至少一种的反应单体形成的共聚物：
    第一单体：包括丙烯酸、甲基丙烯酸、甲基丙烯酸甲酯、甲基丙烯酸叔丁酯、甲基丙烯酸异冰片酯、羟甲基丙烯酰胺、丙烯酰胺、苯乙烯、丙烯腈；
    第二单体：包括丙烯酸C4-C22烷基酯、丙烯酸异丁酯、丙烯酸异辛酯、丙烯酸叔丁酯、丙烯酸-2-乙基己酯(异辛酯)、丙烯酸环己酯、甲基丙烯酸乙酯、甲基丙烯酸异丁酯、甲基丙烯酸-2-乙基己酯、甲基丙烯酸正己酯、甲基丙烯酸环己酯、甲基丙烯酸苄酯、丙烯酸-2-羟乙酯、丙烯酸-2-羟丙酯、甲基丙烯酸亚乙基脲乙酯、甲基丙烯酸双环戊烯乙氧基酯、甲基丙烯酸四氢呋喃酯、甲基丙烯酸三氟乙酯、甲基丙烯酸二甲氨基乙酯、甲基丙烯酸二乙氨基乙酯、甲基丙烯酸亚乙基脲乙酯、甲基丙烯酸丙烯酯、甲基丙烯酸双环戊烯乙氧基酯、甲基丙烯酸四氢呋喃酯、甲基丙烯酸三氟乙酯；
    第三单体：包括甲基丙烯酸-2-羟乙酯、甲基丙烯酸-2-羟丙酯、丙烯酸缩水甘油酯、甲基丙烯酸缩水甘油酯、甲基丙烯酸二甲氨基乙酯、甲基丙烯酸二乙氨基乙酯、乙烯基三甲氧基硅烷、乙烯基三乙氧基硅烷、乙烯基三异丙氧基硅烷、3-甲基丙烯酰氧基丙基三甲氧基硅烷、N-羟甲基丙烯酰胺、N-丁氧甲基(甲基)丙烯酰胺、二丙酮丙烯酰胺、甲基丙烯酸乙酰乙酸乙酯、二乙烯基苯、环氧值在0.35-0.50的环氧树脂、二乙烯苯；
    反应型分散剂：包括聚乙烯醇、聚丙烯醇、聚丙烯乙二醇、聚乙二醇、聚乙烯酸醇。
  24. 根据权利要求18-23中任一项所述的隔离膜，其中，所述第二增塑剂包括甘油C4-C10烷基二醚、甘油C4-C10烷基单醚、甘油C4-C10羧酸单酯、甘油C4-C10羧酸二酯、丙二醇C4-C10烷基单醚和甘油中的至少之一。
  25. 根据权利要求1-24中任一项所述的隔离膜，其中，所述压敏涂层还包括有机颗粒，所述有机颗粒包括聚四氟乙烯颗粒、聚三氟氯乙烯颗粒、聚氟乙烯颗粒、聚偏二氟乙烯颗粒、聚乙烯颗粒、聚丙烯颗粒、聚丙烯腈颗粒、聚环氧乙烷颗粒、含氟烯基单体单元与乙烯基单体单元的共聚物颗粒、含氟烯基单体单元与丙烯酸类单体单元的共聚物颗粒、含氟烯基单体单元与丙烯酸酯类单体单元的共聚物颗粒，以及上述各均聚物或共聚物的改性化合物颗粒中的至少之一，所述有机颗粒和所述复合颗粒在所述涂层表面形成所述凸起。
  26. 根据权利要求25所述的隔离膜，其中，所述有机颗粒形成第三团聚体。
  27. 根据权利要求26所述的隔离膜，其中，所述第三团聚体的Dv50为5μm-30μm，优选为5.0μm-12μm。
  28. 根据权利要求25或26所述的隔离膜，其中，所述第三团聚体中包括一次颗粒形貌的有机颗粒，并且相邻两个所述有机颗粒之间具有间隙。
  29. 根据权利要求28所述的隔离膜，其中，所述一次颗粒形貌的有机颗粒的Dv50为50nm-400nm，优选100nm-200nm。
  30. 根据权利要求25-29中任一项所述的隔离膜，其中，所述复合颗粒与所述有机颗粒的质量比为(20-90)：(0-70)，优选(45-90)：(0-45)。
  31. 根据权利要求1-30中任一项所述的隔离膜，其中，所述压敏涂层的平均厚度为 2μm-20μm，可选为2μm-15μm。
  32. 一种制备权利要求1-31中任一项所述隔离膜的方法，其中，包括：在基材的至少部分表面上形成压敏涂层，所述压敏涂层包括聚丙烯酸酯颗粒和第一增塑剂，所述复合颗粒在所述压敏涂层表面形成凸起，所述复合颗粒包括聚丙烯酸酯颗粒和无机颗粒，至少两个所述聚丙烯酸酯颗粒之间具有所述无机颗粒，所述第一增塑剂的溶解度参数与所述复合颗粒的溶解度参数差值的绝对值为0.3MPa1/2-4MPa1/2。
  33. 一种电池，包括根据权利要求1-31中任一项所述的隔离膜或采用权利要求32所述方法得到的隔离膜。
  34. 一种用电装置，其包括权利要求33所述的电池，所述电池用于提供电能。
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