WO2023274143A1 - 隔膜及其制备方法、二次电池和用电设备 - Google Patents

隔膜及其制备方法、二次电池和用电设备 Download PDF

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Publication number
WO2023274143A1
WO2023274143A1 PCT/CN2022/101495 CN2022101495W WO2023274143A1 WO 2023274143 A1 WO2023274143 A1 WO 2023274143A1 CN 2022101495 W CN2022101495 W CN 2022101495W WO 2023274143 A1 WO2023274143 A1 WO 2023274143A1
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Prior art keywords
base film
coating
diaphragm
organic
inorganic
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Ceased
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PCT/CN2022/101495
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English (en)
French (fr)
Inventor
张新枝
邓耀明
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to EP22831957.0A priority Critical patent/EP4354629A4/en
Priority to CN202280039228.4A priority patent/CN117461208A/zh
Publication of WO2023274143A1 publication Critical patent/WO2023274143A1/zh
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M50/423—Polyamide 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
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of batteries, in particular to a diaphragm, a preparation method thereof, a secondary battery and electrical equipment.
  • the heat resistance of the separator is crucial to the safety performance of the secondary battery. Improving the heat resistance of the separator can reduce the chance of internal short circuit of the secondary battery, improve the ability of the secondary battery to resist short circuit, and improve the safety of the secondary battery.
  • the heat resistance of the diaphragm is reflected in the integrity at high temperature (no shrinkage at high temperature) and high temperature strength (no damage at high temperature, generally reflected by the rupture temperature, where the rupture temperature is the temperature when the diaphragm structure ruptures at high temperature),
  • the existing diaphragm can improve the high-temperature strength of the diaphragm by coating a heat-resistant coating, but its shrinkage performance is poor, and the shrinkage rate is often greater than 5%; by coating an organic-inorganic composite coating, although the diaphragm can be improved Shrinkage performance, but the rupture temperature of the obtained separator is generally lower than 220 ° C, and the safety performance of the separator cannot be further improved. Therefore, the current separator cannot meet the requirements of
  • the present application provides a diaphragm, a preparation method thereof, a secondary battery and electrical equipment, so as to improve the high-temperature shrinkage performance of the diaphragm while increasing the rupture temperature of the diaphragm.
  • the present application provides a diaphragm, which includes a base film, at least one inorganic coating and at least one organic coating, the base film, the inorganic coating and the organic coating are stacked, and at least the base film One side of the surface is in contact with the inorganic coating, wherein the volume content of the organic heat-resistant resin in the organic coating is 60% to 99%, the volume fraction of the inorganic particles in the organic coating is 1% to 40%, and the organic heat-resistant resin The lower of the melting point or decomposition temperature is ⁇ 200°C.
  • the separator provided by the present application is provided with both an inorganic coating and an organic coating, and at least one layer of the inorganic coating is in direct contact with the base film.
  • the inorganic coating has good thermal stability and dimensional stability, which can improve the high-temperature dimensional stability of both the base film and the organic coating, and reduce the shrinkage of the diaphragm at high temperatures;
  • the organic coating It contains an organic heat-resistant resin with a melting point or decomposition temperature ⁇ 200°C.
  • the high melting point of the organic heat-resistant resin can maintain a certain strength of the diaphragm at high temperature without damage, and increase the rupture temperature of the diaphragm.
  • the combination of inorganic coating and organic coating can ensure that the separator has both low shrinkage rate and high membrane rupture temperature at high temperature, achieving excellent heat resistance.
  • the volume content of the organic heat-resistant resin in each layer of organic coating is 60% to 99%, and the organic heat-resistant resin can form a continuous network structure in the organic coating to ensure that the organic coating has sufficient high-temperature strength.
  • inorganic particles are also included in the organic coating to improve the processing performance of the organic coating and prevent problems such as wrinkles and edge sags in the organic coating, and the volume fraction of the inorganic particles is 1% to 40%, so as to avoid the damage caused by the inorganic particles. Excessive addition will lead to low organic heat-resistant resin content, which will adversely affect the high-temperature strength of the organic coating.
  • the base film may be a polyolefin porous film.
  • the base film includes a first polyolefin resin, the first polyolefin resin is ultra-high molecular weight polyethylene with a weight average molecular weight ⁇ 600,000, and the first polyolefin resin is The mass content in the film is >50%.
  • the base film further includes a second polyolefin resin and/or a third polyolefin resin, wherein the melting point of the second polyolefin resin is less than the melting point of the first polyolefin resin, and the third polyolefin resin The melting point of the olefin resin>the melting point of the first polyolefin resin.
  • the first polyolefin resin can choose a polyolefin resin with a melting point > 130°C
  • the second polyolefin resin can choose a polyolefin resin with a melting point ⁇ 130°C
  • the third polyolefin resin can choose a melting point > 150°C of polyolefin resins.
  • the third polyolefin resin can be selected from polypropylene, poly-1-butene, poly-1-pentene, poly-1-hexene, poly-4-methyl-1-pentene, poly-1-octene, polyacetic acid At least one of vinyl ester, polymethyl methacrylate, polystyrene, polyvinylidene fluoride, or polytetrafluoroethylene.
  • the second polyolefin may be polypropylene, poly-4-methyl-1-pentene, or a mixture of polypropylene and poly-4-methyl-1-pentene.
  • the mass content of the third polyolefin resin in the base film is 5% to 30%.
  • the closed cell temperature and shrinkage rate of the base film can be adjusted.
  • the weight per unit thickness of the base film is ⁇ 0.62 g/m 2 / ⁇ m, the porosity is ⁇ 35%, and the average pore diameter is ⁇ 45 nm. In a preferred embodiment of the present application, the weight per unit thickness of the base film is ⁇ 0.64 g/m 2 / ⁇ m, 25% ⁇ porosity ⁇ 35%, and average pore diameter ⁇ 43nm.
  • the elongation of the base film is ⁇ 130%, preferably ⁇ 150%, more preferably ⁇ 180%.
  • the elongation of the base film includes a transverse elongation and a longitudinal elongation, and in the embodiment of the present application, both the transverse elongation and the longitudinal elongation of the base film are ⁇ 130%.
  • the closed cell temperature of the base film is ⁇ 145°C, preferably ⁇ 140°C, more preferably ⁇ 135°C.
  • the membrane rupture temperature of the basement membrane is ⁇ 155°C, preferably ⁇ 160°C, more preferably ⁇ 180°C.
  • the thickness of the base film is 1-16 ⁇ m, preferably 1-9 ⁇ m, more preferably 1-7 ⁇ m.
  • the closed cell effect of the base film can be effectively improved, and at the same time, the secondary battery using the separator can maintain a good fast charging capacity and a high energy density.
  • each layer of inorganic coating contains inorganic particles, and the volume content of the inorganic particles in the inorganic coating is >80%. In a preferred embodiment of the present application, in each layer of inorganic coating, the volume content of inorganic particles is 85%-99%, so as to improve the thermal stability of the base film.
  • the particle size of the inorganic particles is D50 ⁇ 2um, preferably D50 ⁇ 500nm.
  • the thickness of each inorganic coating layer is ⁇ 4 ⁇ m. In a possible implementation of the present application, the thickness of each inorganic coating layer is less than half the thickness of the base film, so as to improve the pore-closing performance of the separator while improving the dimensional stability of the separator.
  • the organic heat-resistant resin in the organic coating, can be selected from aromatic polyamide, polyimide, polyamideimide, polyetherimide, polysulfone, polyketone , at least one of polyether ketone or polytetrafluoroethylene.
  • the aromatic polyamide may be selected from poly-p-phenylene terephthalamide and/or poly-m-phenylene isophthalamide.
  • the thickness of each organic coating layer is 0.5-5 ⁇ m, preferably 1-4 ⁇ m.
  • a separator according to an embodiment of the present application includes an organic coating, an inorganic coating, a base film, an inorganic coating and an organic coating arranged in sequence.
  • At least one outermost surface of the diaphragm is provided with an adhesive layer.
  • the adhesive layer it can be used to connect with the pole piece of the secondary battery when the secondary battery is assembled, so as to improve the integration degree of the secondary battery, increase the hardness of the secondary battery, and improve the mechanical safety performance of the secondary battery.
  • the closed cell temperature of the diaphragm is ⁇ 140°C, preferably ⁇ 138°C, more preferably ⁇ 137°C; the rupture temperature is ⁇ 220°C, preferably ⁇ 230°C, more preferably ⁇ 260°C.
  • the elongation rate is ⁇ 130%, preferably ⁇ 150%, more preferably ⁇ 180%; the shrinkage rate at 150°C for 0.5h is ⁇ 5%, preferably ⁇ 3%, more preferably ⁇ 2.5% .
  • the elongation of the separator includes a transverse elongation and a longitudinal elongation, and in the embodiment of the present application, both the transverse elongation and the longitudinal elongation of the separator can reach a range of ⁇ 150%.
  • the present application also provides a method for preparing a diaphragm, the preparation method comprising:
  • An organic coating is formed on the surface of the other side of the base film and/or the surface of at least one inorganic coating.
  • the separator obtained by using this preparation method has the same properties as the separator in the first aspect of the present application, and will not be repeated here.
  • forming an inorganic coating on at least one surface of the base film includes: forming an inorganic slurry containing inorganic particles, coating the inorganic slurry on at least one surface of the base film, After drying, an inorganic coating is formed.
  • forming an organic coating on the surface of the other side of the base film and/or on the surface of at least one inorganic coating includes: forming an organic slurry containing an organic heat-resistant resin, incorporating the organic The slurry is coated on the surface of the other side of the base film and/or the surface of at least one layer of inorganic coating, and the organic coating is formed after drying.
  • the preparation method further includes: melting and mixing the raw materials of the base film, and extruding to form a gel-like sheet, and the gel-like sheet is stretched once, extracted, and twice After stretching and heat setting, the base film is formed.
  • parameters such as air permeability, thermal shrinkage rate, porosity and mechanical strength of the obtained base film can be adjusted to obtain a base film with various properties that meet the requirements.
  • one stretching includes transverse stretching and longitudinal stretching, and the stretching ratio of transverse stretching and longitudinal stretching is 3-6 times, so as to facilitate the control of appropriate crystallinity, so that the base The film obtains better extensibility and mechanical strength.
  • the secondary stretching includes transverse stretching and longitudinal stretching, and the stretching ratio of the transverse stretching to the longitudinal stretching is 1-2 times.
  • the present application also provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and the separator of the first aspect of the application or the separator obtained by the preparation method of the second aspect of the application , the diaphragm and between the positive pole piece and the negative pole piece, the electrolyte is filled between the positive pole piece and the negative pole piece and wets the diaphragm.
  • the secondary battery of the present application includes the diaphragm of each possible embodiment of the first aspect of the present application. Since the diaphragm of the first aspect of the present application has a high membrane rupture temperature and low shrinkage rate, the secondary battery provided by the present application can have better security.
  • the secondary battery of the present application may be, for example, a lithium-ion battery, a sodium-ion battery, a potassium-ion battery, a calcium-ion battery, or a magnesium-ion battery.
  • the present application provides an electric device including the secondary battery according to the third aspect of the present application.
  • the electrical equipment of the present application includes the secondary battery according to the third aspect of the application, on the basis of the high safety of the secondary battery of the present application, the electrical equipment of the present application also has high safety.
  • the electrical equipment of the present application may include, for example, mobile phones, computers, wearable devices, mobile power supplies, electric vehicles, and energy storage devices.
  • Fig. 1 is a schematic diagram of the charging and discharging principle of a secondary battery according to an embodiment of the present application
  • Fig. 2 is a schematic structural diagram of a diaphragm according to an embodiment of the present application
  • Fig. 3 is a schematic structural diagram of a diaphragm according to another embodiment of the present application.
  • Fig. 4 is a schematic diagram of the preparation process of the base film of an embodiment of the present application.
  • Fig. 5 is a schematic structural diagram of a diaphragm according to another embodiment of the present application.
  • FIG. 1 is a schematic diagram of a working principle of a charging and discharging process of a lithium-ion battery.
  • lithium ions are extracted from the lattice of the positive electrode material, inserted into the negative electrode material after passing through the electrolyte and through the separator 13, and electrons flow from the positive electrode sheet 11 to the negative electrode sheet 12; during discharge, Lithium ions are extracted from the negative electrode material, inserted into the crystal lattice of the positive electrode material after passing through the electrolyte and the separator 13, and the electrons flow from the negative electrode sheet 12 to the positive electrode sheet 11 to supply power to the external terminal equipment.
  • the electrolyte is a carrier for lithium ions to be transmitted between the positive and negative electrodes.
  • the separator 13 is a non-conductive film layer that can pass through lithium ions and prevent electrons from penetrating, so as to separate the positive and negative electrodes to prevent short circuit.
  • the separator 13 shrinks or is damaged at high temperature, resulting in a short circuit between the positive and negative electrodes, the heat generated inside the secondary battery will increase sharply, which may easily cause the secondary battery to burn or explode.
  • the main causes of secondary battery combustion or explosion are mechanical abuse, electrical abuse, and thermal abuse, resulting in damage to the diaphragm 13 and short-circuiting the positive and negative electrodes of the secondary battery.
  • the short-circuit heat generated by the internal short circuit will further cause the diaphragm 13 to shrink or be damaged at high temperatures.
  • thermal abuse refers to the abuse test of the secondary battery in terms of heat (or high temperature), such as a hot box test (high temperature ⁇ 130 degrees to bake the battery cell);
  • mechanical abuse refers to the abuse test of the secondary battery in terms of external mechanical force, Such as foreign object extrusion, acupuncture test, impact test, etc.
  • the heat resistance of the diaphragm is mainly reflected in the integrity at high temperature (no shrinkage at high temperature) and high temperature strength (no damage at high temperature).
  • the inventors of the present application found in the research that: the existing diaphragm is coated with an organic heat-resistant coating, although It can improve the high-temperature strength of the diaphragm, but its shrinkage performance is poor, and the shrinkage rate at 150 degrees is often greater than 5%; when the organic-inorganic composite coating is applied, the base film will The polyolefin resin in the film has been in a molten state and loses its mechanical strength. The inorganic particles have a skeleton structure and do not have good mechanical strength. The high temperature strength is only provided by the organic heat-resistant layer.
  • the inorganic particles will destroy the porous network structure of the organic coating. Mechanical strength, this damage will be more serious at high temperature. Therefore, although the existing diaphragm improvement method can improve the shrinkage performance of the diaphragm, the rupture temperature of the obtained diaphragm is generally lower than 220° C., and the safety performance of the diaphragm cannot be further improved. Therefore, the current separator cannot meet the requirements of low shrinkage and high rupture temperature at the same time at high temperature.
  • an embodiment of the present application provides a diaphragm.
  • the terms used in the following examples are for the purpose of describing particular examples only, and are not intended to limit the application.
  • the singular expressions "a”, “an”, “above”, “the” and “this” are intended to also include such as “one or multiple” unless the context clearly indicates otherwise.
  • references to "one embodiment” or “some embodiments” or the like in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application.
  • appearances of the phrases “in one embodiment,” “in some embodiments,” “in other embodiments,” “in other embodiments,” etc. in various places in this specification are not necessarily All refer to the same embodiment, but mean “one or more but not all embodiments” unless specifically stated otherwise.
  • the terms “including”, “comprising”, “having” and variations thereof mean “including but not limited to”, unless specifically stated otherwise.
  • Fig. 2 is a schematic structural diagram of a diaphragm according to an embodiment of the present application.
  • the separator 13 includes a base film 131 (referred to as A), at least one layer of inorganic coating 132 (referred to as B) and at least one layer of organic coating 133 (can be denoted as C), and at least one inorganic coating layer 132 is in contact with the base film 131 .
  • the number of layers of the base film can be 1 layer
  • the number of layers of the inorganic coating 132 can be 1 layer, 2 layers, 3 layers, 4 layers or more
  • the number of layers of the organic coating 133 can be 1 layer. , 2 layers, 3 layers, 4 layers or more.
  • the number of layers of the inorganic coating and the organic coating is not specifically limited, as long as it includes the base film, the inorganic coating and the organic coating at the same time and satisfies that there is a layer of inorganic coating 132 directly in contact with the base film 131 Just set it up.
  • the separator 13 includes a base film 131 , an inorganic coating 132 and an organic coating 133 .
  • the base film 131 , the inorganic coating 132 and the organic coating 133 are sequentially stacked, and the inorganic coating 132 is disposed between the base film 131 and the organic coating 133 .
  • the diaphragm 13 of this structure can be recorded as an ABC structure.
  • Fig. 3 is a schematic structural diagram of a diaphragm according to another embodiment of the present application.
  • the diaphragm includes a base film 131 , two inorganic coating layers 132 and two organic coating layers 133 .
  • two layers of inorganic coatings 132 are respectively disposed on two surfaces of the base film 131
  • two layers of organic coatings 133 are respectively disposed on both sides of the base film 131 and on the surface of the inorganic coating 132 .
  • the diaphragm 13 of this structure can be denoted as CBABC.
  • the diaphragms of the embodiments of the present application include but are not limited to the following structures: BAC, BABC, BACB, CABC, ABCB, CBACB, ABCBC, BACBC or CABCB, etc.
  • the separator contains multiple layers of inorganic coatings
  • the components of the inorganic coatings can be the same or different.
  • the composition of the organic coatings can be the same or different.
  • the thickness of each layer of inorganic coatings can be the same or different, wherein the inorganic coatings on both sides of the base film can preferably be set to the same thickness to achieve a symmetrical distribution .
  • the thickness of each layer of organic coatings can be the same or different, wherein, the organic coatings on both sides of the base film can preferably be set to the same thickness to achieve Symmetrical distribution.
  • the separator of the embodiment of the present application the inorganic coating and the organic coating are arranged in layers, which can more effectively improve the safety performance of the secondary battery.
  • the inorganic coating is provided separately to ensure the dimensional stability of the separator at high temperature.
  • the organic coating is provided separately, so that the separator can obtain higher high-temperature strength, and the membrane rupture temperature is significantly increased.
  • the separator of the embodiment of the present application after the organic heat-resistant resin forms a porous network layer, it can still maintain high mechanical strength at high temperature.
  • the diaphragm of the embodiment of the present application through the layered arrangement of the inorganic coating and the organic coating, not only ensures the high temperature dimensional stability of the diaphragm, but also ensures the high temperature mechanical properties of the diaphragm, so that the diaphragm has a higher membrane rupture temperature , resulting in high heat resistance.
  • the separator of the example can achieve a closed cell temperature of ⁇ 140°C, a membrane rupture temperature of ⁇ 220°C, a shrinkage rate of ⁇ 5% and an elongation rate of ⁇ 150% at 150°C for 0.5h, thereby effectively improving the integrity of the secondary battery.
  • Mild heat abuse or mechanical abuse state When the lithium-ion battery is in a mild heat abuse or mechanical abuse state, the internal heat of the lithium-ion battery is not much, and when the temperature reaches the closed cell temperature of the separator, the polyolefin porous membrane starts to close the cells, At the same time, the effect of closing cells with inorganic coating is better. At this time, the ion pathway of the diaphragm is cut off, which can inhibit further heat generation inside the lithium-ion battery and prevent problems such as combustion or explosion.
  • the base film, the inorganic coating and the organic coating will be specifically described below.
  • the base film 131 may be a polyolefin porous film.
  • the material forming the polyolefin porous membrane may include a first polyolefin resin, specifically, as an example, the first polyolefin resin may be an ultra-high molecular weight polyethylene resin with a weight average molecular weight ⁇ 600,000, which may be 60-500 Wan's ultra-high molecular weight polyethylene resin.
  • the content of the first polyolefin resin is greater than 50%, and the melting point of the first polyolefin resin can be greater than 130°C, so that the polyolefin porous membrane has better mechanical processing performance and higher mechanical strength.
  • the polyolefin porous membrane may further include a second polyolefin resin and a third polyolefin resin.
  • the melting point of the second polyolefin resin may be ⁇ the melting point of the first polyolefin resin
  • the melting point of the third polyolefin resin may be >the melting point of the first polyolefin resin.
  • the second polyolefin resin may be polyethylene with a melting point lower than 130°C. Based on the total weight of the polyolefin porous membrane, the content of the second polyolefin resin is 0-45%.
  • polyethylene may preferably have a melting point range of 110 to 130°C.
  • polyolefins with a molecular weight of 5 to 1 million are preferred among the second polyolefin resins.
  • the closed cell temperature of the base film can be improved by adding polyethylene with a melting point lower than 130°C. Among them, the closed cell temperature of the separator is also important for the safety performance of the secondary battery.
  • the closed cell temperature of the polyolefin porous membrane is ⁇ 145°C, more preferably ⁇ 140°C, most preferably ⁇ 135°C.
  • the third polyolefin resin may be a polyolefin resin with a melting point higher than 150° C., and may be selected from polypropylene, poly-1-butene, poly-1-pentene, poly-1-hexene, poly-4-methane At least one of base-1-pentene, poly-1-octene, polyvinyl acetate, polymethyl methacrylate, polystyrene, polyvinylidene fluoride or polytetrafluoroethylene, preferably polypropylene and poly-4-methyl-1-pentene mixture.
  • the content of the third polyolefin resin may be 5%-30%.
  • the rupture temperature of the polyolefin porous membrane itself can be improved.
  • the membrane rupture temperature of the polyolefin porous membrane is ⁇ 155°C, more preferably ⁇ 160°C, and most preferably ⁇ 180°C.
  • the closed cells of the base film are achieved by melting and flowing or shrinking of the polyethylene resin after reaching the melting point, so as to close the original pores of the base film to achieve the closed cell effect. Incomplete closure of the basement membrane can still cause internal short circuit and cause thermal runaway.
  • factors of the closed cell effect of the basement membrane in addition to the composition of the basement membrane itself, factors such as the weight per unit thickness, porosity, pore diameter, and thickness of the basement membrane will also affect the closed cell effect of the basement membrane.
  • too small porosity and pore size will affect the permeability of ions, thereby affecting the fast charging ability of the secondary battery.
  • the porosity of the base film preferably 5% ⁇ porosity ⁇ 35%, more preferably 25% ⁇ porosity ⁇ 35%; the average pore diameter of the base film ⁇ 45nm, preferably ⁇ 43nm, to balance the safety performance and fast charging capability of the secondary battery.
  • the thickness and weight of the polyolefin porous membrane also have a certain influence on the effect of closed cells.
  • the thickness of the polyolefin porous membrane is relatively thick, such as >16 ⁇ m, the content of polyethylene resin in the polyolefin porous membrane is relatively large, and the effect of completely closed cells can be achieved.
  • the thickness of the polyolefin porous membrane may be set to 1-16 ⁇ m, preferably 1-12 ⁇ m, more preferably 1-9 ⁇ m, further preferably 1-7 ⁇ m.
  • the weight per unit thickness of the base film is ⁇ 0.62g/m 2 / ⁇ m, preferably ⁇ 0.64g/m 2 / ⁇ m, thereby balancing the safety of the secondary battery and the effect of energy density.
  • the transverse (transverse direction, TD) elongation at break and the longitudinal (machine direction, MD) elongation at break of the polyolefin porous film are both ⁇ 130%, preferably ⁇ 150%, more preferably ⁇ 180% .
  • the rupture temperature of the membrane can be improved.
  • the preparation process of the base film will be described below. It can be understood that the following preparation method is only an optional preparation method of the base film, and the preparation method of the base film is not limited to the following preparation methods.
  • Fig. 4 is the preparation method of the base film of an embodiment of the present application, as shown in Fig. 4, as an illustration, in one embodiment of the present application, the preparation method of the base film comprises the following steps:
  • Step S11 mixing the polyolefin resin raw material and solvent to obtain a mixed melt: melt and knead the polyolefin resin raw material, solvent and additives in a twin-screw extruder to form a uniform liquid phase; wherein, the boiling point of the solvent higher than the mixing temperature.
  • the polyolefin resin raw material is designed according to the required functions of the polyolefin porous membrane, which can be an ultra-high molecular weight polyethylene resin with a molecular weight of 500,000 to 2 million and a melting point of 130 to 138°C; it can also be a combination of various polyethylenes.
  • polyolefin porous membranes can contain copolymerized polyethylene with a melting point of 120-130°C and a molecular weight of 10,000-1 million to improve the closing temperature of polyolefin porous membranes; it can also be a mixture of polyethylene and other types of polyolefins, and other
  • the type of polyolefin is preferably polypropylene or poly-4-methyl-1-pentene, which is used to improve the membrane rupture temperature of the polyolefin porous membrane.
  • the solvent can be aliphatic or cyclic hydrocarbons such as nonane, decane, decalin, p-xylene, undecane, dodecane or liquid paraffin, or mineral oil with a boiling point similar to the above-mentioned specific solvents Fractions etc.
  • the mixing temperature needs to be 30-50°C higher than the melting point of the polyolefin resin raw material, specifically, it can be 180-270°C, or 180-230°C.
  • Additives can be one or more of antioxidants, nano-inorganic fillers, and nucleating agents, and other additives can also be added according to the actual needs of the product.
  • Step S12 extrusion molding: Extrude the homogeneously mixed melt through a slit-type die head, and the extruded melt is cooled on a cooling roll and cast into a sheet to form a gel-like sheet. It is the solid-liquid phase separation state of the liquid phase solvent and the solid phase polyolefin; the gap between the slits is usually 0.1-5mm.
  • Step S13 stretching to form a film: the gel-like sheet is stretched after heating to form reserved holes, and at the same time, the mechanical strength is improved and the crystallinity is improved; stretching includes stretching in MD and TD directions, and the stretching method Any one of bidirectional synchronous stretching, bidirectional asynchronous stretching, and bidirectional combined stretching (combination of synchronous and asynchronous) can be selected. From the perspective of obtaining a more uniform pore size, the bidirectional simultaneous stretching method is preferred. From the point of view of the design of mechanical properties of polyolefin porous membrane, the stretching ratio in MD and TD directions is designed to be 3 to 6 times, which is conducive to controlling the appropriate crystallinity and obtaining better extensibility and mechanical strength.
  • the stretch ratio is the ratio of the dimension of the gel-like sheet in a certain direction after stretching to the dimension of the direction before stretching.
  • the stretching ratio in the MD direction is the ratio of the size of the gel-like sheet after being stretched in the MD direction to the size before stretching
  • the stretching ratio in the TD direction is the ratio of the stretched gel-like sheet in the TD direction.
  • Step S14 extracting and preparing a porous structure: the stretched film is extracted with an extractant, the solvent in the film is removed, and then dried to obtain a porous structure film;
  • the extractant can be dichloromethane, carbon tetrachloride, diethyl ether, ammonium Volatile solvents such as alkane or hexane.
  • Step S15 secondary stretching, and heat setting to obtain a polyolefin porous film: the porous film after extraction and drying needs to be further stretched twice, and the temperature of the secondary stretching is between the crystal dispersion temperature and the melting point, preferably Between 105 and 130 ° C; the stretching ratio is preferably 1 to 2 times; finally, the polyolefin porous film obtained through heat setting treatment, that is, the base film.
  • the heat setting step can adjust some physical parameters of the polyolefin porous membrane within a certain range, such as: heat shrinkage rate, air permeability value, etc.
  • the inorganic coating 132 is an inorganic heat-resistant layer.
  • the inorganic coating 132 may include inorganic particles and a binder.
  • the volume percentage of inorganic particles can be >80%, preferably 85%-99%, more preferably 90%-95%.
  • the volume content of inorganic particles in the inorganic coating can be, for example, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.
  • a certain amount of binder is added to form an adhesive force between the inorganic particles and between the inorganic particles and the polyolefin porous film, forming a stable inorganic coating 132 .
  • the inorganic particles may be selected from the group consisting of alumina, silica, titania, zirconia, zinc oxide, barium oxide, magnesia, beryllium oxide, calcium oxide, thorium oxide, aluminum nitride, titanium nitride, boehmite At least one of stone, apatite, aluminum hydroxide, magnesium hydroxide, barium sulfate, boron nitride, silicon carbide, silicon nitride, cubic boron nitride, hexagonal boron nitride, graphite, graphene or mesoporous molecular sieve kind.
  • the adhesive may be selected from at least one of polyacrylates and hexafluoropropylene-polyvinylidene fluoride.
  • the particle size of the inorganic particles is D50 ⁇ 2um, preferably D50 ⁇ 500nm.
  • the particle size D50 of the inorganic particles is typically but not limited to, for example, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 120nm, 140nm, 160nm, 200nm, 250nm, 300nm, 400nm, 500nm , 700nm, 800nm, 1000nm, 1500nm or 1800nm, etc.
  • the thickness of the inorganic coating may be ⁇ 4 ⁇ m, such as 4 ⁇ m, 3.5 ⁇ m, 3 ⁇ m, 2.5 ⁇ m, 2 ⁇ m, 1.5 ⁇ m or 1 ⁇ m. In one embodiment of the present application, the thickness of each layer of inorganic coating is less than half of the thickness of the polyolefin porous membrane.
  • the inorganic coating is mainly used to improve the overall thermal shrinkage performance of the separator.
  • the polyolefin porous membrane When performing the function of closing cells, the less the amount of molten polyolefin required to penetrate into the inorganic coating, the better the effect of closing cells. Therefore, in the inorganic coating, the particle size of the inorganic particles is D50 ⁇ 2um, especially D50 ⁇ 500nm, and when the thickness of each layer of the inorganic coating is less than or equal to 4 ⁇ m, the inorganic coating can provide excellent thermal shrinkage resistance at the same time, Achieve excellent closed cell effect.
  • the preparation process of the inorganic coating is described below. It can be understood that the following preparation method is only an optional preparation method of the inorganic coating, and the preparation method of the inorganic coating is not limited to the following preparation methods. Wherein, the preparation of the inorganic coating can choose either an aqueous solvent system or an organic solvent system.
  • the preparation method of the inorganic coating includes the following steps: when selecting an aqueous solvent system, mix inorganic particles, adhesive polyacrylates, thickener carboxymethyl cellulose Sodium (carboxymethylcellulose sodium, CMC), dispersant, and water are evenly dispersed in a certain proportion, and then coated on the surface of the polyolefin porous membrane, and then dried to remove moisture.
  • the adhesive polyvinylidene fluoride poly vinylidene fluoride, PVDF
  • organic solvent such as N-methylpyrrolidone (N-Methylpyrrolidone, NMP)
  • NMP N-methylpyrrolidone
  • each layer of organic coating 133 contains an organic heat-resistant resin with a melting point or decomposition temperature ⁇ 200° C. to provide high-temperature strength for the diaphragm 13 .
  • the melting point of the organic heat-resistant resin is the temperature when the organic heat-resistant resin changes from a solid state to a molten state;
  • the decomposition temperature of the organic heat-resistant resin is the temperature when the molecular chain of the organic heat-resistant resin is broken.
  • the volume content of the organic heat-resistant resin in each layer of organic coating 133 is 60%-99%, so as to form a stable and continuous network structure, so that it has high temperature stability.
  • the volume content of the organic heat-resistant resin can be, for example, 61%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% %.
  • the higher the content of the organic heat-resistant resin with melting point or decomposition temperature ⁇ 200°C the higher the high temperature strength of the organic coating.
  • the organic heat-resistant resin can be selected from aromatic polyamide, polyimide, polyamideimide, polyetherimide, polysulfone, polyketone, polyetherketone or At least one of polytetrafluoroethylene; wherein, the aromatic polyamide can be selected from at least one of poly-p-phenylene terephthalamide or poly-m-phenylene isophthalamide. Considering comprehensive factors such as temperature resistance, flame retardancy, and processability in organic solvents, polym-phenylene isophthalamide is the most preferred.
  • inorganic particles can be added to the organic coating 133 to improve the processability of the organic coating 133 , for example, to improve the performance of the organic coating 133 such as anti-wrinkle and anti-sag.
  • the addition of inorganic particles in the organic coating 133 can facilitate the formation of a pore structure in the organic coating 133 and improve the gas permeability of the organic coating.
  • the amount of inorganic particles added may not exceed 40% based on the volume percentage. If the addition of inorganic particles is too high, the content of the organic heat-resistant resin will be low, and the inorganic particles will be dispersed in the fiber network of the organic heat-resistant resin, which will destroy the fiber network structure formed by the organic heat-resistant resin and form many strength defect sites. , the addition of too much inorganic particles will adversely affect the high temperature strength of the organic coating.
  • the thickness of each layer of organic coating 133 is 0.5-5 ⁇ m, preferably 1-4 ⁇ m, so that the organic coating 133 has excellent heat resistance while avoiding energy consumption of the secondary battery. Density takes its toll.
  • the organic coating is provided in the secondary battery, preferably facing the cathode of the secondary battery.
  • the preparation process of the organic coating is described below. It can be understood that the following preparation method is only an optional preparation method of the organic coating, and the preparation method of the organic coating is not limited to the following preparation methods.
  • the preparation process of the organic heat-resistant layer is: dissolve the organic heat-resistant resin in a good solvent for the resin, and add an appropriate amount of pore-forming agent to form a slurry with a certain concentration , coating the slurry on the surface of the polyolefin porous membrane or the surface of the composite membrane covered with an inorganic coating, solidifying and forming pores, washing with water, and drying to obtain a separator coated with an organic coating.
  • LiCl or CaCl 2 can be added to improve the solubility.
  • the slurry coating methods are not limited to the following: reverse roll coating, gravure coating, extrusion coating, hanger coating, wire rod coating, spray coating.
  • the good solvent when preparing the slurry of the organic coating, can be selected from any one or more of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.
  • the volume content of the organic heat-resistant resin can be 3-10%, and the volume content of the good solvent can be more than 50%.
  • inorganic particles can also be dispersed in the slurry, and the total volume content of the inorganic particles and the organic heat-resistant resin in the slurry can be ⁇ 40%.
  • the pore-forming agent can be selected from ethanol, propanol, isopropanol, n-butanol, isobutanol, secondary One or more of butanol, tertiary butanol, neopentyl alcohol, ethylene glycol, propylene glycol, tripropylene glycol, and water.
  • the volume content of the pore-forming agent in the slurry is ⁇ 50%. In the mixed solution of water and good solvent, the volume content of water is >50%.
  • the closed cell temperature of the diaphragm of the embodiment of the application can be ⁇ 145 ° C, preferably ⁇ 140 ° C, more preferably ⁇ 137 ° C; the membrane rupture temperature > 170 ° C, preferably ⁇ 220°C, more preferably ⁇ 260°C; elongation in both directions ⁇ 130%, preferably ⁇ 150%, more preferably ⁇ 180%; thermal shrinkage at 150°C for 30 minutes ⁇ 5%, preferably ⁇ 4%, more preferably ⁇ 3%.
  • Fig. 5 is a schematic structural diagram of a diaphragm according to an embodiment of the present application.
  • the separator 13 may further include an adhesive layer 134 in addition to the base film 131 , the inorganic coating 132 and the organic coating 133 .
  • the adhesive layer 134 can be one layer or two layers, and is disposed on the outermost surface of the diaphragm 13 .
  • the adhesive layer 134 can be located on one side of the outermost surface of the diaphragm 13; when the diaphragm 13 contains two layers of adhesive layer 134, the two layers of adhesive layer 134 may be respectively disposed on the outermost surfaces of both sides of the diaphragm 13 .
  • the adhesive layer 134 contains an adhesive resin, and the adhesive resin may be selected from at least one of acrylic resin and hexafluoropropylene-polyvinylidene fluoride resin.
  • the acrylic binder resin can be, for example, polymethyl methacrylate (PMMA) and its modified products.
  • the preparation method of the adhesive layer is not particularly limited, and water is preferably used as the solvent system, which is similar to the preparation method of the water-based inorganic coating.
  • the coating process of the adhesive layer includes but is not limited to at least one of reverse roll coating, gravure coating, rotary spray coating, and air spray coating.
  • the appearance of the adhesive layer is that the agglomerates of the adhesive resin particles are intermittently distributed randomly, and the thickness of each adhesive layer is 1-8 um.
  • the materials of different adhesive layers 134 can be the same or different.
  • the adhesive layer 134 can realize the interface bonding between the separator and the pole pieces of the secondary battery, so that the secondary battery can realize an integrated structural configuration, and at the same time increase the hardness of the battery to improve the mechanical safety performance of the secondary battery.
  • the present application also provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and the diaphragm of the above-mentioned embodiments of the application, the diaphragm and a battery between the positive electrode sheet and the negative electrode. Between the sheets, the electrolyte is filled between the positive electrode sheet and the negative electrode sheet and wets the separator.
  • the secondary batteries in the embodiments of the present application include but are not limited to lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, calcium-ion batteries, or magnesium-ion batteries.
  • the secondary battery of the embodiment of the present application includes the diaphragm of the embodiment of the present application. Since the diaphragm of the embodiment of the present application has a high membrane rupture temperature and low shrinkage rate, the secondary battery of the embodiment of the present application can have better safety .
  • the secondary battery using the separator of the present application will be specifically described below in combination with specific examples and comparative examples.
  • the application is a lithium ion battery, and the specific raw materials and preparation process of the lithium ion battery are as follows:
  • Polyolefin composition Ultra-high molecular weight polyethylene with a melting point of 136°C and a molecular weight of 1 million, low-melting polyethylene with a melting point of 125°C and a molecular weight of 600,000; polypropylene with a melting point of 165°C and a molecular weight of 500,000 in a ratio of 55:30:15
  • Ratio and paraffin oil are melted and mixed at high temperature in a twin-screw extruder, the ratio of polyolefin composition to paraffin oil is 25:75, the mixing temperature is 190-220°C, and the homogeneous melt passes through a slot die Head extrusion, casting on cooling rollers to form a gel sheet, the cooling rate is 85°C/min; then the gel sheet is first stretched 5 times in the MD direction, and then stretched 5 times in the TD direction.
  • step (2) inorganic coating (B)
  • the ratio of 0.2 is uniformly dispersed in deionized water at a high speed to form a slurry, the solid content of the slurry is 30%, and the viscosity is 500mpa.s; the uniformly dispersed slurry adopts the gravure reverse roll coating method, and is obtained in step (1) successively Both sides of the polyolefin porous membrane are coated with an inorganic coating, and the moisture in the wet membrane is removed by drying in a hot air oven.
  • the thickness of each inorganic heat-resistant layer is 1 ⁇ m.
  • Poly-m-phenylene isophthalamide (referred to as meta-aramid fiber) and inorganic particles are dissolved in a mixed solvent of good solvent N-methylpyrrolidone and pore-forming agent propylene glycol at a volume ratio of 90:10 to form a slurry, wherein , the volume ratio of N-methylpyrrolidone and propylene glycol is 60:40, and the mass concentration of meta-aramid fiber is 6.5%; the slurry adopts the method of gravure reverse roll coating double-sided simultaneous coating in step (2) gained coating Both surfaces of the composite film coated with the inorganic coating are coated with an organic coating, and a diaphragm is obtained after drying, and the thickness of each organic heat-resistant layer is 2 ⁇ m.
  • the structure of the diaphragm formed in this embodiment is in the form of CBABC, as shown in Figure 2, that is, the diaphragm is in order from the outermost side to the outermost side in the thickness direction: organic coating/inorganic coating/base film/inorganic coating / organic coating.
  • Positive electrode sheet production Stir and mix the positive active material lithium cobaltate, the conductive agent conductive carbon black, and the binder polyvinylidene fluoride in N-methylpyrrolidone solvent at a mass ratio of 97:1.5:1.5 to form a positive electrode slurry material, using coating equipment to evenly coat the positive electrode slurry on both sides of the aluminum foil, and drying in an oven to remove the N-methylpyrrolidone solvent.
  • the coated pole piece is made into a positive pole piece after cold pressing, slitting, and tab welding processes.
  • Negative electrode sheet production Negative electrode active material artificial graphite, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber are stirred and evenly mixed in deionized water in a weight ratio of 97:1.3:1.7 to form a negative electrode slurry.
  • the coating equipment evenly coats the negative electrode slurry on both sides of the copper foil, and the electrode sheet after drying in the oven is made into the negative electrode sheet through the processes of cold pressing, slitting, and tab welding.
  • the above-mentioned positive electrode sheet, negative electrode sheet and the separator of this embodiment are wound together to form a bare cell, and then the lithium-ion battery is produced through packaging, baking, liquid injection, standing, formation, degassing, and capacity. Battery.
  • the capacity of the battery cell is 4.5Ah, and the working voltage range is 3.0-4.45V.
  • Examples 2 to 47 are respectively a lithium ion battery, and the preparation method of the separator is referred to in Example 1.
  • the specific raw materials and structural parameters of the separator are listed in Table 1.
  • the diaphragm also includes the step of coating an adhesive layer after coating the organic coating during the preparation process.
  • the specific coating process of the adhesive layer is as follows: the adhesive resin PVDF
  • the powder or PMMA powder uses water as a solvent and adds an acrylic adhesive to form a mixed solution with a concentration of 15%, wherein the mass ratio of the adhesive resin PVDF powder or PMMA powder to the acrylic adhesive is 95:5.
  • the uniformly dispersed slurry is coated on one or both sides of the diaphragm obtained in step (3) with rotary spraying equipment or gravure reverse roll equipment, and after drying, a diaphragm.
  • Comparative example 1 is a lithium ion battery, and the preparation process is as follows:
  • Base film The preparation process of the base film is the same as in Example 1.
  • Inorganic coating no
  • the organic heat-resistant coating slurry also contains inorganic particles, wherein the volume ratio of the organic heat-resistant resin to the inorganic particles is 40:60, and the other preparation methods are the same as in Example 1.
  • the composite diaphragm structure is in the form of CAC, that is, organic coating/substrate/organic coating.
  • Comparative example 2 is a lithium ion battery, and the preparation process is as follows:
  • Base film The resin raw material only uses ultra-high molecular weight polyethylene with a melting point of 136°C and a molecular weight of 1 million.
  • the cooling rate of the cast sheet is 70°C/min, and the multiples of the MD and TD directions of one stretch are both 7. Times, the multiple of TD direction secondary stretching is 1.1 times, and other manufacturing parameters are identical with embodiment 1.
  • Inorganic coating no
  • the organic heat-resistant coating slurry also contains inorganic particles, wherein the volume ratio of the organic heat-resistant resin to the inorganic particles is 40:60, and the other preparation methods are the same as in Example 1.
  • the composite diaphragm structure is in the form of CAC, that is, organic coating/substrate/organic coating.
  • Comparative example 3 is a lithium ion battery, and the preparation process is as follows:
  • Base film The resin raw material only uses ultra-high molecular weight polyethylene with a melting point of 136°C and a molecular weight of 1 million.
  • the cooling rate of the cast sheet is 70°C/min, and the multiples of the MD and TD directions of one stretch are both 7. Times, the multiple of TD direction secondary stretching is 1.1 times, and other manufacturing parameters are identical with embodiment 1.
  • Inorganic coating no
  • Organic coating the organic coating only contains organic heat-resistant resin, and other preparation methods are the same as in Example 1.
  • the composite diaphragm structure is in the form of CAC, that is, organic coating/substrate/organic coating.
  • Comparative example 4 is a lithium ion battery, and the preparation process is as follows:
  • Base film the preparation method of the base film in Comparative Example 3 is the same.
  • Inorganic coating the same as the preparation method of the inorganic coating in Example 1.
  • the composite diaphragm structure is in the form of BAB, that is, organic coating/substrate/organic coating.
  • Comparative example 5 to comparative example 15 are respectively a kind of lithium-ion battery, wherein, the preparation method of diaphragm therein refers to the preparation process of base film, inorganic coating or organic coating in embodiment 1 or comparative example 1-4, diaphragm
  • the specific raw materials and structural parameters are listed in Table 1-5.
  • the base film into strips with a width of 15mm and a length of more than 50mm (for example, 100mm) according to the MD and TD directions. If the elongation in the MD direction is tested, the width 15mm refers to the TD direction of the base film, and the length 100mm refers to the MD direction of the base film; if the elongation in the TD direction is tested, the width 15mm refers to the MD direction of the base film, and the length is 100mm refers to the TD direction of the basement membrane.
  • the above-mentioned strips are subjected to a tensile test using a multifunctional tensile machine.
  • a multimeter thickness gauge to test the thickness of at least 10 points along the TD direction of the base film, and take the average value as the thickness of the base film.
  • the temperature rise internal resistance method is used for testing. Place the diaphragm in a stainless steel jig or other similar jig and inject an appropriate amount of electrolyte, place the above jig in an oven, heat up at 2°C/min, and monitor the resistance and temperature of the jig at the same time. When the resistance value suddenly increases ( 10 times) is the closed cell temperature of the diaphragm.
  • thermomechanical analysis TMA Tested by thermomechanical analysis (TMA).
  • the effective test dimensions between the test fixtures are: sample width 5mm, length 10mm, loading force 11.7mN, heating rate: 10°C/min, temperature range: room temperature to 400°C.
  • the film rupture temperature is the temperature at which the sample ruptures or breaks when tested under the above conditions.
  • the cell is tested at 100% depth of charge (step of charge, SOC), that is, fully charged in the standard charging mode, and tested within 12 to 24 hours. Extrude the largest surface of the cell parallel to the table top, place a M1.4 ⁇ 3.0 screw on the upper surface of the cell, and then squeeze the plane of the cell vertically with a metal block, release the pressure when the pressure reaches 13 ⁇ 1kN, every Each sample is tested only once in one direction. The battery passes the test if it does not catch fire or explode. 10 groups were tested for each group of samples, and the pass rate was recorded.
  • step of charge SOC
  • test it within 12 to 24 hours.
  • the battery passes the test if it does not catch fire or explode. 10 groups were tested for each group of samples, and the pass rate was recorded.
  • thermocouple fixing the contact of the thermocouple on the center of the cell surface
  • the battery passes the test if it does not catch fire or explode.
  • Diaphragm processing efficiency When the diaphragm is coated, the area of the diaphragm before coating is S1, the area of the diaphragm that meets the appearance requirements after coating and winding is S2, and the processing efficiency is S2/S1*100%.
  • a diaphragm that meets the appearance requirements means no curling, no wrinkling, no uneven winding, and no ribbing.
  • Diaphragm air permeability value Test with Asahi Seiko Co., Ltd. air permeability tester, adjust the intake pressure to 0.25MPa, test pressure to 0.05Mpa, test time for 5S, and test the air permeability value of the diaphragm sample.
  • the particle size D50 of the inorganic particles in the inorganic coating is within the range of 0.5 ⁇ m ⁇ 0.1 ⁇ m, and the single-layer thickness of the inorganic coating is 2-3 ⁇ m. In Examples 1-16 and Comparative Examples 1-3, the single-layer thickness of the organic coating is 2-3 ⁇ m.
  • the thickness of the organic coating is 2-3 ⁇ m.
  • the particle size D50 of the inorganic particles in the inorganic coating is in the range of 0.5 ⁇ m ⁇ 0.1 ⁇ m, and the single layer thickness of the inorganic coating is 2-3 ⁇ m.
  • the particle size D50 of the inorganic particles in the inorganic coating is within the range of 0.5 ⁇ m ⁇ 0.1 ⁇ m, and the single-layer thickness of the inorganic coating is 2-3 ⁇ m.
  • the particle size D50 of the inorganic particles in the inorganic coating is in the range of 0.5 ⁇ m ⁇ 0.1 ⁇ m, and the single layer thickness of the inorganic coating is 2-3 ⁇ m.
  • Table 1 lists the effects of different polyolefin porous membrane designs in the separator on the separator and lithium-ion battery. It can be seen from the data in Table 1 that the diaphragm structure of this application has a good safety effect. When polyolefin porous membranes with different characteristics are used as the base film, the safety effect of the diaphragm will be different, but they are all better than those of the diaphragm structure of the comparative example. Security effect.
  • the polyolefin porous membrane is preferably a substrate having at least one characteristic of low-temperature cell closure, high membrane rupture and high elongation, and most preferably a substrate having three characteristics at the same time.
  • Example 1 adopts the CBABC structure. Compared with the diaphragm of the CAC structure of Comparative Example 1, when both surfaces of the base film have inorganic coatings, because The inorganic coating has little effect on the closed cell temperature of the base film. Therefore, compared with the closed cell temperature of the base film, the separator in Example 1 only increased by 1 °C from 136 °C of the base film, and still maintained a good closed cell temperature of the base film. Pore effect. In Comparative Example 1, an organic-inorganic composite coating was used, which had a certain influence on the closing cell effect of the base film, and the closing cell effect decreased significantly when the temperature increased from 136°C to 140°C.
  • the inorganic coating maintains the heat shrinkage rate of the separator in Example 1 at a level of 3.0%, and the heat shrinkage rate of the organic-inorganic composite coating in Comparative Example 1 is too large to reach 10%, and the heat shrinkage rate has no effect on heat abuse and Mechanical abuse has a greater impact.
  • the organic coating of Example 1 has a higher organic heat-resistant resin content, and the organic coating formed has higher strength at high temperatures, which supports the closed-cell effect of the polyolefin porous membrane and the inorganic coating at a higher temperature. Maintained at high temperature without failure due to membrane rupture, the membrane rupture temperature of the separator in Example 1 was as high as 280°C. In Comparative Example 1, the strength of the organic phase was greatly destroyed by the inorganic particles in the organic-inorganic composite coating, resulting in a significant decrease in the strength of the diaphragm at high temperatures, and the rupture temperature could only reach 200°C.
  • the separator adopted in Example 1 not only has a relatively low closed cell temperature, can respond to early thermal abuse in a timely manner, but also has dimensional stability, high membrane rupture temperature, and good closed cell maintenance state under higher temperature conditions. Azimuthally isolate the positive and negative electrodes of the lithium-ion battery to reduce the occurrence of short circuits and provide a guarantee for battery safety. Therefore, the pass rate of the 100% SOC foreign body extrusion test of the battery of Example 1 is 95%, the pass rate of the 150°C hot box is 100%, and the pass rate of Comparative Example 1 is 60%. The safety effect of embodiment 1 is better.
  • Table 2 lists the effects of the design of different inorganic coatings in the separator on Li-ion batteries.
  • the diaphragm of this application has a good safety effect.
  • Different inorganic coating designs may have different safety effects of the diaphragm, but they are all better than the safety effect of the comparative diaphragm structure.
  • the inorganic coating is preferably coated on both sides of the base film surface, and the smaller the inorganic particles and the thicker the inorganic coating, the better the safety effect.
  • inorganic coatings can be designed according to battery energy density requirements and acceptable safety performance.
  • Table 3 lists the effects of the design of different organic coatings in the separator on Li-ion batteries.
  • the organic coating within the scope of this application, the organic coating of organic heat-resistant resin with melting point or decomposition temperature > 200°C, wherein the content of organic heat-resistant resin is in the range of 60% to 99%, and the thickness of a single layer is 0.5 to 5um can show more Excellent high temperature film breaking effect, better processing performance and air permeability.
  • Table 4 lists the effects of different structural designs in the separator on Li-ion batteries.
  • the safety effects of diaphragms with different structures are different, but they are all better than the safety effects of the comparison examples.
  • the structure of the separator can be designed according to the requirements of battery energy density and acceptable safety performance.
  • the structure of the diaphragm of the present application is not limited to the structures of the above-mentioned embodiments, and all structures meeting the requirements of the present application have good safety effects.
  • Table 5 lists the influence of the tie layer in the separator on the lithium-ion battery.
  • the adhesive layer can improve the interface bonding of the battery cell and the hardness of the battery, and has a certain effect on improving the mechanical properties, but the interface bonding and battery hardness can also be achieved through the battery preparation process. After the adhesive layer is used in the diaphragm of the present application, the safety effect is also better than that of the comparative example using the adhesive layer.
  • the separator of this application can provide good closed-cell function and excellent heat resistance at the same time through the synergistic effect between different layers, and the closed-cell temperature and membrane rupture temperature The temperature difference between them can reach 130°C, even up to 140°C. Therefore, the diaphragm of the embodiment of the present application is a safety diaphragm with a wide temperature range under high temperature.
  • the closed cell temperature, membrane rupture temperature, ambient temperature during measurement, elongation, shrinkage, film thickness, particle size and other specific values involved in this application are affected by the accuracy of the measuring equipment, and there may be certain errors , for example, there may be an error of 1%, and when the parameters involved in the present application fluctuate within the above error range, it should also be understood as being within the protection scope of the present application.

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Abstract

本申请提供了一种隔膜及其制备方法、二次电池和用电设备。该隔膜包括基膜、至少一层无机涂层和至少一层有机涂层，基膜、无机涂层与有机涂层之间叠层设置，且基膜的至少一侧表面与无机涂层接触，其中，有机涂层中有机耐热树脂的体积含量为60％～99％，有机涂层中含有无机颗粒的体积分数为1％～40％，有机耐热树脂的熔点或分解温度中较低者≥200℃。该结构的隔膜能够在提高隔膜破膜温度的同时，改善隔膜高温收缩性能。

Description

隔膜及其制备方法、二次电池和用电设备
相关申请的交叉引用
本申请要求在2021年06月30日提交中国专利局、申请号为202110730735.X、申请名称为“隔膜及其制备方法、二次电池和用电设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池领域，具体涉及一种隔膜及其制备方法、二次电池和用电设备。
背景技术
目前二次电池已被广泛应用于消费类终端设备如手机、笔记本、穿戴设备、移动电源、电动汽车及储能领域中，然而二次电池的失效事故频繁发生，其安全性能已成为重点研究方向。二次电池的失效主要表现为热失控导致的冒烟、起火、燃烧、爆炸。而导致热失控的诱因主要有机械碰撞、过充/过放、高温过热等，导致二次电池内部发生短路。当二次电池内部发生短路时，会进一步造成隔膜在高温下收缩或破损，这将造成更大的短路面，进而导致二次电池燃烧失效。因此，隔膜的耐热性对于二次电池的安全性能至关重要。提升隔膜的耐热性可以减少二次电池内部短路发生的机会，提升二次电池抗短路的能力，改善二次电池的安全性。隔膜的耐热性体现在高温下的完整性(高温不收缩)和高温强度(高温不破损，一般用破膜温度体现，其中，破膜温度为隔膜在高温下结构发生破裂时的温度)，而现有的隔膜通过涂覆耐热涂层，虽然可提高隔膜的高温强度，但是其收缩性能较差，收缩率往往大于5％；通过涂覆有机-无机复合涂层，虽可以改善隔膜的收缩性能，但是所得隔膜的破膜温度一般低于220℃，也无法进一步改善隔膜的安全性能。因此，目前的隔膜在高温下还不能同时满足低收缩和高破膜温度的要求。
发明内容
本申请提供了一种隔膜及其制备方法、二次电池和用电设备，以在提高隔膜破膜温度的同时，改善隔膜高温收缩性能。
第一方面，本申请提供一种隔膜，该隔膜包括基膜、至少一层无机涂层和至少一层有机涂层，基膜、无机涂层与有机涂层叠层设置，且基膜的至少一侧表面与无机涂层接触，其中，有机涂层中有机耐热树脂的体积含量为60％～99％，有机涂层中含有无机颗粒的体积分数为1％～40％，有机耐热树脂的熔点或分解温度中较低者≥200℃。
本申请提供的隔膜，同时设置有无机涂层和有机涂层，且至少一层无机涂层直接和基膜接触。该结构的隔膜中，无机涂层具有较好的热稳定性和尺寸稳定性，可同时改善基膜和有机涂层两者的高温尺寸稳定性，降低隔膜在高温下的收缩率；有机涂层中含有熔点或分解温度≥200℃的有机耐热树脂，该有机耐热树脂的高熔点，能够使隔膜在高温下维持一定的强度而不发生破损，提高隔膜的破膜温度。无机涂层与有机涂层搭配使用，可保证隔膜在高温下同时具有较低的收缩率和较高的破膜温度，实现优异的耐热性。其中，每层 有机涂层中的有机耐热树脂的体积含量为60％～99％，有机耐热树脂在有机涂层中可形成连续的网状结构，以保证有机涂层具有足够的高温强度。此外，有机涂层中还包括无机颗粒以用于改善有机涂层的加工性能，防止有机涂层出现褶皱、塌边等问题，且无机颗粒的体积分数为1％～40％，避免因无机颗粒添加量过高导致有机耐热树脂含量偏低，从而对有机涂层的高温强度造成不利影响。
在本申请一种可能的实现方式中，基膜可为聚烯烃多孔膜。具体的，在本申请一种可能的实现方式中，基膜包括第一聚烯烃树脂，第一聚烯烃树脂为重均分子量≥60万的超高分子量聚乙烯，且第一聚烯烃树脂在基膜中的质量含量＞50％。
在本申请一种可能的实现方式中，基膜还包括第二聚烯烃树脂和/或第三聚烯烃树脂，其中，第二聚烯烃树脂的熔点＜第一聚烯烃树脂的熔点，第三聚烯烃树脂的熔点＞第一聚烯烃树脂的熔点。
其中，作为示例性说明，第一聚烯烃树脂可选择熔点＞130℃的聚烯烃树脂，第二聚烯烃树脂可选择熔点＜130℃的聚烯烃树脂，第三聚烯烃树脂可选择熔点＞150℃的聚烯烃树脂。
其中，第三聚烯烃树脂可选自聚丙烯、聚1-丁烯、聚1-戊烯、聚1-己烯、聚4-甲基-1-戊烯、聚1-辛烯、聚乙酸乙烯酯、聚甲基丙烯酸甲酯、聚苯乙烯、聚偏二氟乙烯或聚四氟乙烯中的至少一种。优选地，第二聚烯烃可为聚丙烯、聚4-甲基-1-戊烯、或聚丙烯与聚4-甲基-1-戊烯的混合物。
在本申请一种可能的实现方式中，当基膜中含有第三聚烯烃树脂时，第三聚烯烃树脂在基膜中的质量含量为5％～30％。
通过调整基膜中各成分的组成，可调整基膜的闭孔温度和收缩率。
在本申请一种可能的实现方式中，基膜的单位厚度重量≥0.62g/m 2/μm，孔隙率<35％，平均孔径<45nm。在本申请一种优选的实施方式中，基膜的单位厚度重量≥0.64g/m 2/μm，25％＜孔隙率<35％，平均孔径<43nm。
在本申请一种可能的实现方式中，基膜的延伸率≥130％，优选≥150％，进一步优选≥180％。其中，基膜的延伸率包括横向延伸率和纵向延伸率，在本申请实施例中，基膜的横向延伸率和纵向延伸率均≥130％。
在本申请一种可能的实现方式中，基膜的闭孔温度≤145℃，优选≤140℃，进一步优选≤135℃。
在本申请一种可能的实现方式中，基膜的破膜温度≥155℃，优选≥160℃，进一步优选≥180℃。
在本申请一种可能的实现方式中，基膜的厚度为1～16μm，优选为1～9μm，进一步优选为1～7μm。
通过限定基膜的单位厚度重量、孔隙率、平均孔径以及厚度，可有效提高基膜的闭孔效果，同时使应用该隔膜的二次电池保持较好的快充能力和较高的能量密度。
在本申请一种可能的实现方式中，每层无机涂层中含有无机粒子，且无机粒子在无机涂层中的体积含量>80％。在本申请一种优选实施方式中，每层无机涂层中，无机粒子的体积含量为85％～99％，以提高基膜的热稳定性。
在本申请一种可能的实现方式中，无机粒子的粒径为D50≤2um，优选为D50≤500nm。通过控制无机粒子的粒径，可有效改善基膜的闭孔效果。
在本申请一种可能的实现方式中，每层无机涂层的厚度≤4μm。在本申请一种可能的实现方式中，每层无机涂层的厚度<基膜厚度的一半，以在改善隔膜尺寸稳定性的同时，改善隔膜的闭孔性能。
在本申请一种可能的实现方式中，有机涂层中，有机耐热树脂可选自芳香族聚酰胺、聚酰亚胺、聚酰胺酰亚胺、聚醚酰亚胺、聚砜、聚酮、聚醚酮或聚四氟乙烯中的至少一种。其中，芳香族聚酰胺可选自聚对苯二甲酰对苯二胺和/或聚间苯二甲酰间苯二胺。
在本申请一种可能的实现方式中，每层有机涂层的厚度为0.5～5μm，优选为1～4μm。通过优化有机涂层的厚度，可在提高隔膜耐热性的同时，使隔膜不会对二次电池的能量密度造成影响。
在本申请一种可能的实现方式中，基膜的两侧表面分别设有至少一层无机涂层和至少一层有机涂层，其中，基膜的两侧表面均与无机涂层接触。其中，作为示例性说明，本申请一种实施方式的隔膜包括依次设置的有机涂层、无机涂层、基膜、无机涂层和有机涂层。
在本申请一种可能的实现方式中，隔膜的至少一个最外表面设有粘结层。通过设置粘结层，在组装二次电池时，可用于与二次电池的极片连接，提高二次电池的一体化程度，同时提高二次电池的硬度，改善二次电池的机械安全性能。
在本申请一种可能的实现方式中，隔膜的闭孔温度≤140℃，优选≤138℃，进一步优选≤137℃；破膜温度≥220℃，优选≥230℃，进一步优选≥260℃。
在本申请一种可能的实现方式中，延伸率≥130％，优选≥150％，进一步优选≥180％；150℃下0.5h的收缩率≤5％，优选≤3％，进一步优选≤2.5％。其中，隔膜的延伸率包括横向延伸率和纵向延伸率，在本申请实施例中，隔膜的横向延伸率和纵向延伸率均可达到≥150％的范围。
第二方面，本申请还提供一种隔膜的制备方法，该制备方法包括：
在基膜的至少一侧表面形成无机涂层；
在基膜的另一侧表面和/或至少一层无机涂层的表面形成有机涂层。
利用该制备方法获得的隔膜具有与本申请第一方面隔膜相同的性能，在此不再赘述。
在本申请一种可能的实现方式中，在基膜的至少一侧表面形成无机涂层，包括：形成含有无机粒子的无机浆料，将无机浆料涂覆于基膜的至少一侧表面，经干燥后形成无机涂层。
在本申请一种可能的实现方式中，在基膜的另一侧表面和/或至少一层无机涂层的表面形成有机涂层，包括：形成含有有机耐热树脂的有机浆料，将有机浆料涂覆于基膜的另一侧表面和/或至少一层无机涂层的表面，干燥后形成有机涂层。
在本申请一种可能的实现方式中，该制备方法还包括：将基膜原料熔融混合，挤压成型后形成凝胶状片材，凝胶状片材依次经一次拉伸、萃取、二次拉伸和热定型后，形成基膜。通过一次拉伸、萃取、二次拉伸和热定型可调整所得基膜的透气值、热收缩率、孔隙率以及机械强度等参数，以获得各项性能满足需求的基膜。
在本申请一种可能的实现方式中，一次拉伸包括横向拉伸和纵向拉伸，横向拉伸与纵向拉伸的拉伸比例为3-6倍，以利于控制合适的结晶度，使基膜获得较好的延伸性和机械强度。
在本申请一种可能的实现方式中，二次拉伸包括横向拉伸和纵向拉伸，横向拉伸与纵向拉伸的拉伸比例为1-2倍。
第三方面，本申请还提供一种二次电池，该二次电池包括正极极片、负极极片、电解液以及本申请第一方面的隔膜或利用本申请第二方面的制备方法得到的隔膜，隔膜以及介于正极极片和负极极片之间，电解液填充于正极极片和负极极片之间且浸润隔膜。
本申请的二次电池包括本申请第一方面各可能实施方式的隔膜，由于本申请第一方面的隔膜具有高破膜温度和低收缩率，因此，本申请提供的二次电池可具有较好的安全性。
其中，本申请的二次电池例如可以为锂离子电池、钠离子电池、钾离子电池、钙离子电池或镁离子电池等。
第四方面，本申请提供了一种用电设备，该用电设备包括本申请第三方面的二次电池。
本申请的用电设备，由于包括本申请第三方面的二次电池，在本申请的二次电池具有较高安全性的基础上，本申请的用电设备也具有较高的安全性。
其中，本申请的用电设备例如可包括手机、电脑、穿戴设备、移动电源、电动汽车及储能装置等。
附图说明
图1为本申请一种实施例的二次电池的充放电原理示意图；
图2为本申请一种实施例的隔膜的结构示意图；
图3为本申请另一种实施例的隔膜的结构示意图；
图4为本申请一种实施例的基膜的制备流程示意图；
图5为本申请另一种实施例的隔膜的结构示意图。
附图标记：
11-正极极片；       12-负极极片；        13-隔膜；           131-基膜；
132-无机涂层；      133-有机涂层；       134-粘结层。
具体实施方式
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
目前，可实现循环充放电的二次电池，例如锂离子电池，已经广泛应用于移动电话、笔记本电脑、便携式电子移动设备以及无人机、电动汽车等终端设备当中。其中，图1为一种锂离子电池充放电过程的工作原理示意图。如图1所示，充电时，锂离子从正极材料的晶格中脱出，经过电解液并穿过隔膜13后插入到负极材料中，电子从正极极片11流向负极极片12；放电时，锂离子从负极材料中脱出，经过电解液并穿过隔膜13后插入到正极材料的晶格中，电子从负极极片12流向正极极片11，对外部终端设备进行供电。电解液是锂离子在正负极之间传输的载体，隔膜13为不导电膜层，可透过锂离子，阻止电子透过，以将正负极隔开防止短路。当隔膜13在高温下发生收缩或破损导致正负极间会发生短路时，二次电池的内部发热量会急剧增加，容易引起二次电池燃烧或爆炸。二次电池燃烧或爆炸的主要诱因有机械滥用、电滥用和热滥用，导致隔膜13破损使二次电池正负极短路，内部短路产生的短路热会进一步造成隔膜13在高温下收缩或破损，造成更大的短路面积从而导致二次电池燃烧或爆炸。因此，隔膜13的耐热性对于锂离子电池安全性能来说至关重要。其中，热滥用指二次电池在热(或高温)方面的滥用测试，比如热箱测 试(高温≥130度烘烤电芯)；机械滥用指二次电池在外部机械作用力方面的滥用测试，比如异物挤压、针刺测试、撞击测试等。
隔膜的耐热性主要体现在高温下的完整性(高温不收缩)和高温强度(高温不破损)，本申请发明人在研究中发现：现有的隔膜通过涂覆有机耐热涂层，虽然可提高隔膜的高温强度，但是其收缩性能较差，150度收缩率往往大于5％；通过涂覆有机-无机复合涂层时，因高温下，例如在超过基膜熔点的温度下，基膜中的聚烯烃树脂已呈熔融态而失去机械强度、无机颗粒是骨架结构也没有良好的机械强度，高温强度仅由有机耐热层提供，因此，无机颗粒会破坏有机涂层中多孔网络结构的机械强度，在高温下这种破坏会更加严重。由此，现有的隔膜改进方法，虽可以改善隔膜的收缩性能，但是所得隔膜的破膜温度一般低于220℃，也不能进一步改善隔膜的安全性能。因此，目前的隔膜高温下还不能同时满足低收缩和高破膜温度的要求。
为了解决该技术问题，本申请实施例提供一种隔膜。以下实施例中所使用的术语只是为了描述特定实施例的目的，而并非旨在作为对本申请的限制。如在本申请的说明书和所附权利要求书中所使用的那样，单数表达形式“一个”、“一种”、“上述”、“该”和“这一”旨在也包括例如“一个或多个”这种表达形式，除非其上下文中明确地有相反指示。
在本说明书中描述的参考“一个实施例”或“一些实施例”等意味着在本申请的一个或多个实施例中包括结合该实施例描述的特定特征、结构或特点。由此，在本说明书中的不同之处出现的语句“在一个实施例中”、“在一些实施例中”、“在其他一些实施例中”、“在另外一些实施例中”等不是必然都参考相同的实施例，而是意味着“一个或多个但不是所有的实施例”，除非是以其他方式另外特别强调。术语“包括”、“包含”、“具有”及它们的变形都意味着“包括但不限于”，除非是以其他方式另外特别强调。
图2为本申请一种实施例的隔膜的结构示意图。如图2所示，在本申请一种实施例中，该隔膜13包括基膜131(可记为A)、至少一层无机涂层132(可记为B)和至少一层有机涂层133(可记为C)，且至少一层无机涂层132与基膜131接触。其中，基膜的设置层数可为1层，无机涂层132的设置层数可为1层、2层、3层、4层或更多，有机涂层133的设置层数可为1层、2层、3层、4层或更多。本申请实施例中，无机涂层和有机涂层的设置层数并不做具体限定，只要同时包括基膜、无机涂层和有机涂层且满足有一层无机涂层132直接与基膜131接触设置即可。
如图2所示，在本申请一种实施例中，该隔膜13包括一层基膜131、一层无机涂层132和一层有机涂层133。其中，基膜131、无机涂层132和有机涂层133依次叠层设置，无机涂层132设于基膜131与有机涂层133之间。该结构的隔膜13可记为ABC结构。
图3为本申请另一种实施例的隔膜的结构示意图。如图3所示，在本申请一种实施例中，该隔膜包括一层基膜131、两层无机涂层132和两层有机涂层133。其中，两层无机涂层132分别设置在基膜131的两个表面，两层有机涂层133分别设置在基膜131的两侧且分别设置在无机涂层132的表面。该结构的隔膜13可记为CBABC。
除图2和图3所示结构的隔膜外，本申请实施例的隔膜还包括但不限于以下结构：BAC、BABC、BACB、CABC、ABCB、CBACB、ABCBC、BACBC或CABCB等。
其中，需要说明的是，当隔膜中包含多层无机涂层时，无机涂层的成分可以相同，也可以不同。当隔膜中包含多层有机涂层时，有机涂层的成分可以相同，也可以不同。当基膜的两侧均设置无机涂层时，每层无机涂层的厚度可以相同也可以不同，其中，设置于基 膜两侧的无机涂层可优选设置为相同的厚度，以实现对称分布。同样，当基膜的两侧均设置有机涂层时，每层有机涂层的厚度可以相同也可以不同，其中，设于基膜两侧的有机涂层可优选设置为相同的厚度，以实现对称分布。
本申请实施例的隔膜，无机涂层和有机涂层采用分层设置的方式，可以更有效地提高二次电池的安全性能。相比于有机-无机复合涂层，无机涂层单独设置，保证了隔膜在高温下的尺寸稳定性。有机涂层单独设置，可使隔膜获得更高的高温强度，破膜温度显著提高。本申请实施例的隔膜中，有机耐热树脂形成多孔网络层后，可在高温下仍保持较高的机械强度。因此，本申请实施例的隔膜，通过无机涂层和有机涂层的分层设置，既保证了隔膜的高温尺寸稳定性，又保证了隔膜的高温机械性能，使隔膜具有较高的破膜温度，从而获得高耐热性。同时，本申请实施例中，至少一层无机涂层与基膜接触，可使基膜发挥更好的闭孔功能，且在有机涂层的保护下，基膜和无机涂层的闭孔效果可在更高温度下维持而不会因发生破膜而失效，最终可使隔膜在高温条件下既有尺寸稳定性、又不会破膜，还处于良好的闭孔状态，例如，本申请实施例的隔膜可实现闭孔温度≤140℃，破膜温度≥220℃，150℃下0.5h的收缩率≤5％，延伸率≥150％，进而有效提升二次电池的完全性。
为方便理解本申请实施例的隔膜对二次电池安全性的作用效果，下面对本申请实施例隔膜的一种可能的作用机理进行解释说明。下面以锂离子电池为例，本申请隔膜对锂离子电池安全改善的可能机理如下：
1)正常工作状态：当锂离子电池温度低于隔膜闭孔温度时，锂离子通过隔膜正常穿梭，锂离子电池处于正常工作状态。
2)温和热滥用或机械滥用状态：当锂离子电池处于温和热滥用或机械滥用状态时，锂离子电池内部发热不多，当温度达到隔膜的闭孔温度时，聚烯烃多孔膜启动闭孔，同时搭配无机涂层闭孔效果更佳。此时隔膜的离子通路被切断，可抑制锂离子电池内部进一步产热，防止燃烧或爆炸等问题。
3)严重热滥用或机械滥用状态：当热滥用或机械滥用状态继续加重，电池内部的发热进一步增加时，隔膜面临更高的温度，在有机涂层的支撑下，无机涂层和聚烯烃多孔膜之间形成的闭孔层仍然维持良好的闭孔效果，隔膜处于闭孔状态，此时，无机涂层和有机涂层相互配合作用，可以维持隔膜整体的高温尺寸稳定性和高温强度，隔膜尺寸完整性好、有一定机械强度且不会破损，即隔膜始终将正负极分隔开并形成断路，减少了短路发生的概率，使电池具有优异的安全性。
下面将分别对基膜、无机涂层和有机涂层进行具体说明。
基膜
一并参照图2和图3，在本申请一种实施例中，基膜131可为聚烯烃多孔膜。形成聚烯烃多孔膜的材料可包括第一聚烯烃树脂，具体地，作为示例性说明，该第一聚烯烃树脂可为重均分子量≥60万的超高分子量聚乙烯树脂，可为60～500万的超高分子量聚乙烯树脂。以聚烯烃多孔膜的总重量计，第一聚烯烃树脂的含量＞50％，该第一聚烯烃树脂的熔点可大于130℃，以使聚烯烃多孔膜具有较好的机械加工性能和较高的机械强度。
另外，在本申请另一实施例中，聚烯烃多孔膜中还可包括第二聚烯烃树脂和第三聚烯烃树脂。其中，第二聚烯烃树脂的熔点可＜第一聚烯烃树脂的熔点，第三聚烯烃树脂的熔点可＞第一聚烯烃树脂的熔点。
作为示例性说明，第二聚烯烃树脂可为熔点低于130℃的聚乙烯。以聚烯烃多孔膜的 总重量计，第二聚烯烃树脂的含量为0～45％。第二聚烯烃树脂中，聚乙烯的熔点范围可优选为110～130℃。为方便基膜的加工，第二聚烯烃树脂中优选分子量为5～100万的聚烯烃。通过添加熔点低于130℃的聚乙烯，可改善基膜的闭孔温度。其中，隔膜的闭孔温度对于二次电池的安全性能也很重要。当二次电池温度升高时，隔膜的孔隙快速闭合，切断离子通路，使整个二次电池形成断路模式，可以大幅降低短路热，防止热量进一步聚集。在本申请一种实施例中，聚烯烃多孔膜的闭孔温度≤145℃，进一步优选≤140℃，最优选≤135℃。
作为示例性说明，第三聚烯烃树脂可为熔点高于150℃的聚烯烃树脂，可选自聚丙烯、聚1-丁烯、聚1-戊烯、聚1-己烯、聚4-甲基-1-戊烯、聚1-辛烯、聚乙酸乙烯酯、聚甲基丙烯酸甲酯、聚苯乙烯、聚偏二氟乙烯或聚四氟乙烯中的至少一种，可优选为聚丙烯和聚4-甲基-1-戊烯的混合物。当聚烯烃多孔膜中含有第三聚烯烃树脂时，第三聚烯烃树脂的含量可为5％～30％。通过添加熔点高于150℃的第三聚烯烃树脂，可以改善聚烯烃多孔膜自身破膜温度。在本申请一种实施例中，聚烯烃多孔膜的破膜温度≥155℃，进一步优选≥160℃，最优选≥180℃。
其中，需要说明的是，基膜的闭孔是通过聚乙烯树脂达到熔点后发生熔融流动或收缩，以封闭基膜原始的孔隙而实现闭孔效果。基膜闭孔不彻底依然能够造成内短路从而引发热失控。而基膜闭孔效果的影响因素中，除了基膜的自身组成成分外，基膜的单位厚度重量、孔隙率、孔径、厚度等因素也会影响基膜的闭孔效果。聚烯烃多孔膜的孔隙率越大，微孔的数量越多，或者孔径越大时，需要越多的聚乙烯树脂来封闭初始孔隙，闭孔难度高、闭孔效果差；反之，孔隙率低，微孔数量越少，或者孔径越小时，闭孔所需聚乙烯树脂的量降低，闭孔难度降低，闭孔程度彻底。但孔隙率和孔径大小太小会影响离子的透过性能，从而影响二次电池的快充能力。在本申请一种实施例中，基膜的孔隙率<35％，优选为5％＜孔隙率<35％，进一步优选为25％＜孔隙率<35％；基膜的平均孔径<45nm，优选<43nm，以平衡二次电池的安全性能和快充能力。
另外，聚烯烃多孔膜的厚度和重量对闭孔效果也有一定的影响。当聚烯烃多孔膜的厚度较厚时，比如>16μm时，聚烯烃多孔膜中聚乙烯树脂的含量较多，可实现完全闭孔的效果。但聚烯烃多孔膜的厚度较厚时，会影响二次电池的能量密度。因此，聚烯烃多孔膜的厚度可设置为1～16μm，优选为1～12μm，进一步优选为1～9μm，进一步优选为1～7μm。
此外，聚烯烃多孔膜的单位厚度重量越重，所能提供的闭孔原料越多，闭孔效果越好。因此，在本申请的一种实施例中，基膜的单位厚度重量≥0.62g/m 2/μm,优选为≥0.64g/m 2/μm，由此，以平衡对二次电池的安全性以及能量密度的影响。
在本申请一种实施例中，聚烯烃多孔膜的横向(transversedirection，TD)断裂伸长率和纵向(machinedirection，MD)断裂伸长率均≥130％，优选≥150％，进一步优选≥180％。由此，以改善隔膜的破膜温度。
下面对基膜的制备过程进行说明。可以理解的是，以下制备方法仅为基膜的一种可选制备方法，基膜的制备方法并非局限于以下制备方法。
图4为本申请一种实施例的基膜的制备方法，如图4所示，作为示例性说明，在本申请一种实施例中，基膜的制备方法包括以下步骤：
步骤S11、将聚烯烃树脂原料和溶剂进行混炼得到混合熔体：将聚烯烃树脂原料、溶剂和添加剂在双螺杆挤出机中进行熔融混炼，形成均一的液相；其中，溶剂的沸点高于混 炼的温度。
其中，聚烯烃树脂原料根据聚烯烃多孔膜所需功能设计，可以是一种分子量为50～200万、熔点为130～138℃的超高分子量聚乙烯树脂；也可以是多种聚乙烯的组合物，其中可含有熔点为120～130℃、分子量为1万～100万的共聚聚乙烯，用来改善聚烯烃多孔膜的闭孔温度；还可以是聚乙烯和其他种类聚烯烃的混合物，其它种类的聚烯烃优选聚丙烯或聚4-甲基-1-戊烯，用来改善聚烯烃多孔膜的破膜温度。
溶剂可以是壬烷、癸烷、萘烷、对二甲苯、十一碳烷、十二碳烷或液体石蜡等脂肪族或环式的烃，或沸点与上述几种具体溶剂相近似的矿油馏分等。
混炼的温度需高于聚烯烃树脂原料的熔点30～50℃，具体可以是180℃-270℃，也可以是180～230℃。
添加剂可以是抗氧剂、纳米无机填料、成核剂中的一种或多种，还可以根据产品实际需要加入其他添加剂。
步骤S12、挤出成型：将混炼均匀的熔体通过狭缝式的模头进行挤出，挤出的熔体在冷却辊上进行冷却、铸片后形成凝胶状片材，该片材是液相溶剂与固相聚烯烃的固-液相分离状态；狭缝的间隙通常为0.1-5mm。
步骤S13、拉伸成膜：凝胶状片材在加热后经过拉伸可以形成预留孔位，同时机械强度提高、结晶度提升；拉伸包括MD和TD两个方向拉伸，拉伸方式可以选择双向同步拉伸、双向异步拉伸、双向组合拉伸(同步和异步的组合)中的任意一种。从获得更加均匀的孔径角度考虑，优选双向同步拉伸方式。从聚烯烃多孔膜机械特性设计的角度考虑，MD和TD方向的拉伸比例均设计在3～6倍，有利于控制合适的结晶度，获得较好的延伸性和机械强度。其中，拉伸比例为凝胶状片材经拉伸后的某一方向的尺寸与拉伸前的该方向尺寸的比值。例如，MD方向的拉伸比例为凝胶状片材在MD方向经拉伸后的尺寸与拉伸前的尺寸的比值；TD方向的拉伸比例为凝胶状片材在TD方向经拉伸后的尺寸与拉伸前的尺寸的比值。
步骤S14、萃取制备多孔结构：拉伸后的薄膜采用萃取剂进行萃取，除去薄膜中的溶剂，再经过干燥得到多孔结构的薄膜；萃取剂可以采用二氯甲烷、四氯化碳、乙醚、戊烷或己烷等易挥发性溶剂。
步骤S15、二次拉伸、热定型后得到聚烯烃多孔膜：经过萃取、干燥后的多孔薄膜需进一步进行二次拉伸，二次拉伸的温度介于晶体分散温度和熔点之间，优选105～130℃之间；拉伸倍数优选1～2倍；最后再经过热定型处理得到的聚烯烃多孔膜，即基膜。热定型步骤可以对聚烯烃多孔膜的部分物性参数进行一定范围内的调节，如：热收缩率、透气值等。
无机涂层
一并参照2和图3，无机涂层132为无机耐热层，在本申请一种实施例中，无机涂层132中可包括无机粒子和粘结剂。其中，以每层无机涂层的体积为基准进行计量，无机粒子所占的体积百分比可>80％，优选为85％～99％，进一步优选为90％～95％。其中，无机涂层中无机粒子的体积含量例如可为81％、82％、83％、84％、85％、86％、87％、88％、89％、90％、91％、92％、93％、94％、95％、96％、97％、98％或99％。
无机涂层132中，无机粒子含量越高，尺寸稳定性越好，热收缩越小。无机涂层中，添加一定量的粘结剂，以使无机粒子之间以及无机粒子与聚烯烃多孔膜之间形成粘接力， 形成稳定的无机涂层132。
作为示例性说明，无机粒子可选自氧化铝、氧化硅、氧化钛、氧化锆、氧化锌、氧化钡、氧化镁、氧化铍、氧化钙、氧化钍、氮化铝、氮化钛、勃母石、磷灰石、氢氧化铝、氢氧化镁、硫酸钡、氮化硼、碳化硅、氮化硅、立方氮化硼、六方氮化硼、石墨、石墨烯或介孔分子筛中的至少一种。
在本申请一种实施例中，粘接剂可选自聚丙烯酸酯类、六氟丙烯-聚偏二氟乙烯中的至少一种。
在本申请一种实施例中，无机粒子的粒径D50≤2um，优选为D50≤500nm。其中，无机粒子的粒径D50典型但非限制性地例如可以为20nm、30nm、40nm、50nm、60nm、70nm、80nm、90nm、100nm、120nm、140nm、160nm、200nm、250nm、300nm、400nm、500nm、700nm、800nm、1000nm、1500nm或1800nm等。
在本申请一种实施例中，无机涂层的厚度可≤4μm，例如可为4μm、3.5μm、3μm、2.5μm、2μm、1.5μm或1μm等。在本申请一种实施例中，每层无机涂层的厚度<聚烯烃多孔膜厚度的一半。
无机涂层主要用于改善隔膜整体的热收缩性能，在无机涂层提供同样热收缩性能的基础上，无机涂层的厚度越薄，无机粒子之间形成的孔隙越小，当聚烯烃多孔膜发挥闭孔功能时，熔融态的聚烯烃渗入无机涂层所需量越少，闭孔效果越好。由此，无机涂层中，无机粒子的粒径D50≤2um，尤其是D50≤500nm，每层无机涂层的厚度小于等于4μm时，可使无机涂层在提供优异抗热收缩性能的同时，达到优异的闭孔效果。
下面对无机涂层的制备过程进行说明。可以理解的是，以下制备方法仅为无机涂层的一种可选制备方法，无机涂层的制备方法并非局限于以下制备方法。其中，无机涂层的制备既可以选择水性溶剂体系也可以选择有机溶剂体系。
作为示例性说明，在本申请一种实施例中，无机涂层的制备方法包括以下步骤：选择水性溶剂体系时，将无机粒子、粘接剂聚丙烯酸酯类、增稠剂羧甲基纤维素钠(carboxymethylcellulose sodium，CMC)、分散剂、水按一定比例分散均匀后涂覆在聚烯烃多孔膜的表面，然后进行干燥以去除水分。在本申请另一种实施例中，选择有机溶剂体系时，将粘接剂聚偏氟乙烯(poly vinylidene fluoride，PVDF)、有机溶剂，如N-甲基吡咯烷酮(N-Methyl pyrrolidone，NMP)溶解成均一溶液，再加入无机粒子分散均匀后涂覆在聚烯烃多孔膜的表面，然后进行凝固、水洗、烘干等工序后得到复合膜。
有机涂层
一并参照图2和图3，在本申请一种实施例中，每层有机涂层133中含有熔点或分解温度≥200℃的有机耐热树脂，以为隔膜13提供高温强度。其中，有机耐热树脂的熔点为有机耐热树脂从固态转变为熔融态时的温度；有机耐热树脂的分解温度为有机耐热树脂分子链发生断裂时的温度。由于有机耐热树脂的种类较多，当有机耐热树脂随着加热温度的提高先发生熔融时，此时需限定有机耐热树脂的熔点≥200℃；当有机耐热树脂随着加热温度的提高，先发生分子链断裂时，此时需限定有机耐热树脂的分解温度≥200℃。
其中，每层有机涂层133中的有机耐热树脂的体积含量为60％～99％，以形成稳定连续的网络结构，使其在具有高温稳定性。其中，以每层有机涂层133的体积为基准计量，有机耐热树脂的体积含量例如可为61％、65％、70％、75％、80％、85％、90％、95％或99％。有机涂层中，熔点或分解温度≥200℃的有机耐热树脂的含量越高，有机涂层的高温强度 越高。
作为示例性说明，有机涂层133中，有机耐热树脂可选自芳香族聚酰胺、聚酰亚胺、聚酰胺酰亚胺、聚醚酰亚胺、聚砜、聚酮、聚醚酮或聚四氟乙烯中的至少一种；其中，芳香族聚酰胺可选自聚对苯二甲酰对苯二胺或聚间苯二甲酰间苯二胺中的至少一种。从耐温性、阻燃性、溶于有机溶剂的可加工型等综合因素考虑，最优选聚间苯二甲酰间苯二胺。
在本申请一种实施例中，有机涂层133中可添加无机颗粒，以用于提高有机涂层133的可加工性，例如可提高有机涂层133的抗皱、抗塌边等性能。另外，有机涂层133中，无机颗粒的加入可有利于有机涂层133形成孔隙结构，提高有机涂层的透气性。
在本申请一种实施例中，每层有机涂层133中，以体积百分比为基准计量，无机颗粒的添加量例如可不超过40％。无机颗粒添加量过高，会导致有机耐热树脂含量偏低，无机颗粒分散在有机耐热树脂的纤维网络中，破坏了有机耐热树脂形成的纤维网络结构，形成很多强度缺陷位点，因此，无机颗粒添加量过高会对有机涂层的高温强度造成不利影响。
在本申请一种实施例中，每层有机涂层133的厚度为0.5～5μm，优选为1～4μm，以使该有机涂层133具有优异耐热性的同时，避免对二次电池的能量密度造成损失。
当隔膜中只设有一层有机涂层时，该有机涂层在二次电池中，优选面向二次电池的阴极设置。
下面对有机涂层的制备过程进行说明。可以理解的是，以下制备方法仅为有机涂层的一种可选制备方法，有机涂层的制备方法并非局限于以下制备方法。
作为示例性说明，在本申请一种实施例中，有机耐热层的制备流程是：将有机耐热树脂溶解于该树脂的良溶剂中，可加入适量造孔剂，形成一定浓度的浆料，将该浆料涂布于聚烯烃多孔膜表面或已覆盖无机涂层的复合膜表面，进行凝固造孔、水洗、干燥后获得覆有有机涂层的隔膜。其中，在本申请一种可选实施例中，为了提升聚间苯二甲酰间苯二胺的溶解性，可以加入LiCl或CaCl 2改善溶解性。浆料的涂覆方式不限于以下几种：逆转辊涂、凹版涂覆、挤压涂覆、挂涂、线棒涂覆、喷涂。
其中，制备有机涂层的浆料时，良溶剂可选自二甲基乙酰胺、二甲基甲酰胺、二甲基亚砜、N-甲基吡咯烷酮中的任一种或多种。浆料中，有机耐热树脂的体积含量可为3～10％，良溶剂的体积含量>50％。根据有机涂层设计需要，也可以在浆料中分散无机颗粒，无机颗粒与有机耐热树脂在浆料中的总体积含量可<40％。
其中，在浆料中加入适量造孔剂可以改善有机涂层的成孔形貌及均匀性，造孔剂可选自乙醇、丙醇、异丙醇、正丁醇、异丁醇、二级丁醇、三级丁醇、新戊醇、乙二醇、丙二醇、三丙二醇、水中的一种或多种。造孔剂占浆料的体积含量≤50％。水和良溶剂的混合溶液中，水的体积含量>50％。
通过优化基膜、无机涂层和有机涂层的组成，可使本申请实施例的隔膜的闭孔温度<145℃，优选≤140℃，进一步优选≤137℃；破膜温度>170℃，优选≥220℃，进一步优选≥260℃；双方向延伸率均≥130％，优选≥150％，进一步优选≥180％；150℃下30min的热收缩率≤5％，优选≤4％，进一步优选≤3％。
图5为本申请一种实施例的隔膜的结构示意图。如图5所示，在本申请一种实施例的隔膜13中，除包括基膜131、无机涂层132和有机涂层133外，还可包括粘结层134。粘结层134可为一层，也可为两层，设于隔膜13的最外表面。当隔膜13中仅设置一层粘结层134时，该粘结层134可设于隔膜13的一侧最外表面；当隔膜13中含有两层粘结层134 时，该两层粘结层134可分别设置在隔膜13的两侧最外表面。
粘结层
参照图5，在本申请一种实施例中，粘结层134中含有粘结树脂，粘结树脂可选自丙烯酸类树脂和六氟丙烯-聚偏二氟乙烯树脂中的至少一种。丙烯酸类粘结树脂例如可以是聚甲基丙烯酸甲酯(polymethyl methacrylate，PMMA)及其改性物。
粘接层的制备方法无特殊限制，优选采用水作为溶剂体系，与水系无机涂层的制备方法类似。
粘接层的涂覆加工方式包含但不局限于逆转辊涂、凹版涂覆、旋转喷涂、空气喷涂中的至少一种。
粘接层的形貌为粘接树脂颗粒的团聚体呈间歇无规分布，每层粘接层的厚度为1～8um。
当隔膜13含有两层粘结层134时，不同粘结层134的材料可以相同，也可以不同。
粘接层134可以实现隔膜与二次电池极片之间的界面粘接，使二次电池实现一体化结构设置，同时提升电池的硬度，以改善二次电池的机械安全性能。
基于同样的技术构思，本申请还提供一种二次电池，该二次电池包括正极极片、负极极片、电解液和本申请上述实施例的隔膜，隔膜以及介于正极极片和负极极片之间，电解液填充于正极极片和负极极片之间且浸润隔膜。
本申请实施例的二次电池包括但不限于锂离子电池、钠离子电池、钾离子电池、钙离子电池或镁离子电池等。
本申请实施例的二次电池包括本申请实施例的隔膜，由于本申请实施例的隔膜具有高破膜温度和低收缩率，因此，本申请实施例的二次电池可具有较好的安全性。
下面将结合具体实施例和对比例对利用本申请隔膜的二次电池做具体说明。
实施例1
本申请为一种锂离子电池，该锂离子电池的具体原料以及制备过程如下：
步骤(1)基膜(A)：聚烯烃多孔膜的制备
聚烯烃组合物：将熔点136℃、分子量100万的超高分子量聚乙烯，熔点125℃、分子量60万的低熔点聚乙烯；熔点165℃、分子量50万的聚丙烯按55:30:15的比例与石蜡油在双螺杆挤出机中高温熔融混炼，聚烯烃组合物与石蜡油的比例为25:75，混炼温度为190～220℃，混炼均匀的熔体经过狭缝式模头挤出，在冷却辊上进行铸片形成凝胶片材，冷却速度为85℃/min；然后凝胶片材先进行MD方向5倍拉伸，再进行TD方向5倍拉伸，拉伸后的薄膜再经过二氯甲烷萃取槽，除去石蜡油组分；萃取后的薄膜经过50℃低温干燥后再在118℃下进行TD方向二次拉伸，拉伸倍数为1.05倍；最后经过120℃热定型后得到聚烯烃多孔膜。
步骤(2)无机涂层(B)的制备
将D50为0.5μm±0.1μm的三氧化二铝粉末、聚丙烯酸酯类粘接剂、增稠剂(羧甲基纤维素钠)、分散剂(聚乙烯醇)按体积比90:6.3:3.5:0.2的比例在去离子水中高速分散均匀形成浆料，浆料的固含量为30％，粘度为500mpa.s；分散均匀的浆料采用凹版逆转辊涂的方式，依次在步骤(1)所得聚烯烃多孔膜的两面进行无机涂层的涂覆，采用热风烘箱的干燥方式除去湿膜中的水分。每层无机耐热层的厚度为1μm。
步骤(3)有机涂层(C)的制备
将聚间苯二甲酰间苯二胺(简称间位芳纶)和无机颗粒按体积比90:10溶解在良溶剂 N-甲基吡咯烷酮和造孔剂丙二醇的混合溶剂中形成浆料，其中，N-甲基吡咯烷酮和丙二醇的体积比例为60:40，间位芳纶的质量浓度为6.5％；将该浆料采用凹版逆转辊涂双面同时涂覆的方式在步骤(2)所得涂覆无机涂层后的复合薄膜的两个表面均涂覆有机涂层，干燥后得到隔膜，每层有机耐热层的厚度为2μm。
该实施例形成的隔膜的结构为CBABC形式，可参照图2，即隔膜从最外一侧按厚度方向到最外另一侧依次为：有机涂层/无机涂层/基膜/无机涂层/有机涂层。
步骤(4)电池组装
正极极片制作：将正极活性材料钴酸锂、导电剂导电炭黑、粘接剂聚偏氟乙烯以质量比97:1.5:1.5的比例在N-甲基吡咯烷酮溶剂中搅拌均匀混合成正极浆料，采用涂布设备将正极浆料均匀涂布在铝箔的两面，经烘箱烘干去除N-甲基吡咯烷酮溶剂。将涂布后的极片经过冷压、分条、极耳焊接工序后制成正极极片。
负极极片制作：将负极活性材料人造石墨、增稠剂羧甲基纤维素钠、粘接剂丁苯橡胶以97:1.3:1.7的重量比例在去离子水中搅拌均匀混合成负极浆料，采用涂布设备将负极浆料均匀涂布在铜箔的两面，经烘箱烘干后的极片经过冷压、分条、极耳焊接工序制成负极极片。
将上述正极极片、负极极片和本实施例的隔膜一起进行卷绕制成裸电芯，再经过封装、烘烤、注液、静置、化成、去气体、容量等工序制成锂离子电池。
其中，电芯的容量为4.5Ah，工作电压范围为3.0-4.45V。
实施例2-47
实施例2至实施例47分别为一种锂离子电池，其中的隔膜的制备方法参照实施例1，隔膜的具体原料以及结构参数列于表1。
其中，实施例42-47的锂离子电池，隔膜在制备过程中在涂覆有机涂层后还包括涂覆粘结层的步骤，粘结层的具体涂覆过程如下：将粘接性树脂PVDF粉料或者PMMA粉料采用水作为溶剂，加入丙烯酸类粘接剂，形成浓度为15％的混合液，其中，粘接性树脂PVDF粉料或者PMMA粉料与丙烯酸类粘接剂的质量比为95:5。混合液经高速分散和研磨后，将分散均匀的浆料采用旋转喷涂设备或者凹版逆转辊设备在步骤(3)所得隔膜上进行单面或双面涂覆，经烘干后得到含有粘接层的隔膜。
对比例1
对比例1为一种锂离子电池，制备过程如下：
基膜：该基膜的制备过程与实施例1相同。
无机涂层：无
有机涂层：有机耐热涂层浆料中还含有无机粒子，其中有机耐热树脂和无机粒子的体积比例为40:60，其它制备方法与实施例1相同。
复合隔膜结构：复合隔膜结构为CAC形式，即有机涂层/基材/有机涂层。
对比例2
对比例2为一种锂离子电池，制备过程如下：
基膜：树脂原料仅采用熔点136℃、分子量为100万的超高分子量聚乙烯，基膜制造工艺中，铸片冷却速度为70℃/min，一次拉伸MD和TD方向的倍数均为7倍，TD方向二次拉伸的倍数为1.1倍，其它制造参数与实施例1相同。
无机涂层：无
有机涂层：有机耐热涂层浆料中还含有无机粒子，其中有机耐热树脂和无机粒子的体积比例为40:60，其它制备方法与实施例1相同。
复合隔膜结构：复合隔膜结构为CAC形式，即有机涂层/基材/有机涂层。
对比例3
对比例3为一种锂离子电池，制备过程如下：
基膜：树脂原料仅采用熔点136℃、分子量为100万的超高分子量聚乙烯，基膜制造工艺中，铸片冷却速度为70℃/min，一次拉伸MD和TD方向的倍数均为7倍，TD方向二次拉伸的倍数为1.1倍，其它制造参数与实施例1相同。
无机涂层：无
有机涂层：该有机涂层中仅含有有机耐热树脂，其它制备方法与实施例1相同。
复合隔膜结构：复合隔膜结构为CAC形式，即有机涂层/基材/有机涂层。
对比例4
对比例4为一种锂离子电池，制备过程如下：
基膜：与对比例3中基膜的制备方法相同。
无机涂层：与实施例1中无机涂层的制备方法相同。
有机涂层：无。
复合隔膜结构：复合隔膜结构为BAB形式，即有机涂层/基材/有机涂层。
对比例5-15
对比例5至对比例15分别为一种锂离子电池，其中，其中的隔膜的制备方法参照实施例1或对比例1-4中的基膜、无机涂层或有机涂层的制备过程，隔膜的具体原料以及结构参数列于表1-5中。
其中，对比例13-对比例15中的粘结层的涂覆过程参照实施例42-47。
性能测试
分别测试实施例1-47以及对比例1-15中的隔膜的各项性能参数，例如基膜的延伸率、基膜的厚度、隔膜的闭孔温度、破膜温度、孔径以及热收缩等，并对相应锂离子电池做异物挤压测试和电池热箱测试。测试结果列于表1-表5。
具体测试过程如下：
1、隔膜中基膜延伸率测试：
将基膜分别按MD和TD方向裁切出宽度15mm、长度大于50mm(比如100mm)的小条。如果测试MD方向的延伸率，则宽度15mm是指基膜的TD方向，长度100mm是指基膜的MD方向；如果测试TD方向的延伸率，则宽度15mm是指基膜的MD方向，长度100mm是指基膜的TD方向。将上述小条采用多功能拉力机进行拉伸测试，测试条件为：样品宽度15mm，测试前上下夹具间基材的长度固定为50mm记为L 0(裁切的样品长度大于50mm是为了方便夹具把基膜夹住)，设置拉力机的拉伸速度为100mm/min。开始拉伸样品，直至样品刚被拉断时夹具间的距离记为L1，延伸率＝(L 1-L 0)/L 0。
2、基膜厚度测试：
采用万分测厚仪沿基膜TD方向测试至少10个点的厚度，取其平均值作为基膜的厚度。
3、闭孔温度：
采用升温内阻法进行测试。将隔膜置于不锈钢夹具或其它类似夹具之内并注入适量电解液，将上述夹具置于烘箱中，以2℃/min进行升温，同时监控夹具的阻值和温度，当阻 值发生突增(10倍)时的温度即为隔膜的闭孔温度。
4、破膜温度：
采用热机械分析法(TMA)测试。测试夹具之间有效测试尺寸为：样品宽度5mm，长度10mm，加载力11.7mN，升温速度：10℃/min，温度范围：室温～400℃。破膜温度为采用上述条件测试时样品破裂或断裂时的温度。
5、孔径：
采用泡点法测试的孔喉处的平均孔径
6、热收缩率：
将隔膜裁切成10cm×10cm尺寸大小，标识MD、TD方向，将裁切好的隔膜放入150℃烘箱烘烤0.5h，测量烘烤前后尺寸，热收缩率＝(烘烤前尺寸-烘烤后尺寸)/烘烤前尺寸。
7、电池异物挤压测试：
电芯按100％充电深度(step of charge，SOC)进行测试，即以标准充电模式充满电，在12～24h以内进行测试。将电芯最大面与台面平行进行挤压，在电芯上表面放置一个M1.4×3.0的螺丝，然后用金属块垂直挤压电芯平面，当压力达到13±1kN时将压力释放，每个样品仅在一个方向上进行一次测试。电芯不起火、不爆炸则通过测试。针对每组样品测试10组，记录通过率。
8、电池热箱测试：
电芯按标准充电模式充满电后，在12～24h以内进行测试。用对流方式或循环热空气箱以起始温度25±3℃进行加热，温变率5±2℃/min，升温至140±2℃，保持30min后结束试验。电芯不起火、不爆炸则通过测试。针对每组样品测试10组，记录通过率。
9、电池过充性能测试：电池进行测试放电，之后放入防爆箱中。接好热电偶(将热电偶的触点固定在电芯表面的中心部位)，并接上电源进行充电，以3C恒定电流充电至4.8V，直至电压达到最大值，满足以下任一条件即可停止测试：
a)持续充电时间达到7h；
b)电芯温度下降到比峰值低20％。
电芯不起火、不爆炸则通过测试。
10、隔膜加工优率：隔膜涂覆处理时，涂覆前的隔膜面积为S1，涂覆收卷后满足外观要求的隔膜面积为S2，加工优率是S2/S1*100％。满足外观要求的隔膜指无卷边、无打皱、无收卷不齐、无暴筋现象。
11、隔膜透气值：采用旭精工株式会社透气度测试仪进行测试，将进气压力调为0.25MPa，测试压力调为0.05Mpa，测试时间为5S，测试隔膜样品的透气值。
表1
Figure PCTCN2022101495-appb-000001
Figure PCTCN2022101495-appb-000002
表1(续1)
Figure PCTCN2022101495-appb-000003
Figure PCTCN2022101495-appb-000004
表1(续2)
Figure PCTCN2022101495-appb-000005
其中，实施例1-16以及对比例4中，无机涂层中无机粒子的粒径D50的范围在0.5μm ±0.1μm范围内，无机涂层的单层厚度2～3μm。实施例1-16以及对比例1-3中，有机涂层的单层厚度2～3μm。
表2
Figure PCTCN2022101495-appb-000006
表2(续)
Figure PCTCN2022101495-appb-000007
Figure PCTCN2022101495-appb-000008
其中，实施例17-27以及对比例5-7中，有机涂层的厚度为2～3μm。
表3
Figure PCTCN2022101495-appb-000009
表3(续)
Figure PCTCN2022101495-appb-000010
Figure PCTCN2022101495-appb-000011
其中，实施例28-36以及对比例8-10中，无机涂层中无机粒子的粒径D50的范围在0.5μm±0.1μm范围内，无机涂层的单层厚度2～3μm。
表4
Figure PCTCN2022101495-appb-000012
其中，实施例37-41以及对比例11-12中，无机涂层中无机粒子的粒径D50的范围在0.5μm±0.1μm范围内，无机涂层的单层厚度2～3μm。
表5
Figure PCTCN2022101495-appb-000013
Figure PCTCN2022101495-appb-000014
其中，实施例42-47以及对比例13-15中，无机涂层中无机粒子的粒径D50的范围在0.5μm±0.1μm范围内，无机涂层的单层厚度2～3μm。
表1列出了隔膜中不同聚烯烃多孔膜设计对隔膜以及锂离子电池的影响。从表1中的 数据可以看出，本申请隔膜结构具有良好的安全效果，采用不同特性的聚烯烃多孔膜作为基膜时，隔膜的安全效果会有差异，但均好于对比例隔膜结构的安全效果。聚烯烃多孔膜优选具有低温闭孔特性、高破膜特性、高延伸率特性至少一种特性的基材，最优选同时具有三种特性的基材。
另外，从实施例1和对比例1的对比还可以看出，实施例1采用CBABC结构，相比对比例1的CAC结构的隔膜，当基膜的两个表面均有无机涂层时，因无机涂层对基膜的闭孔温度影响不大，因此实施例1的隔膜相比基膜的闭孔温度，从基膜的136℃，仅增加了1℃，仍保持了基膜良好的闭孔功效。而对比例1采用的是有机-无机复合涂层，对基膜的闭孔效果有一定影响，从136℃增加到140℃，闭孔效果明显降低。
此外，无机涂层使实施例1的隔膜热收缩率能维持在3.0％的水平，对比例1的有机-无机复合涂层的热收缩率偏大达到10％，而热收缩率对热滥用和机械滥用均有较大影响。
实施例1的有机涂层具有更高的有机耐热树脂含量，形成的有机涂层在高温下具有更高的强度，该强度支撑了聚烯烃多孔膜和无机涂层的闭孔效果可以在更高温度下维持，而不会因发生破膜而失效，实施例1的隔膜破膜温度高达280℃。而对比例1因有机-无机复合涂层中，有机相的强度被无机粒子大幅破坏，造成隔膜在高温下的强度明显降低，破膜温度只能达到200℃。
因此，采用实施例1的隔膜既具有相对低的闭孔温度，能及时响应早期热滥用，同时在更高温条件下具有尺寸稳定性、高的破膜温度，以及良好的闭孔维持状态，全方位隔离锂离子电池的正负极，减少短路发生，为电池安全提供保证。因此，实施例1的电池100％SOC异物挤压测试通过率为95％，150℃热箱通过率为100％，而对比例1的通过率均为60％。实施例1的安全效果更佳。
表2列出了隔膜中不同无机涂层的设计对锂离子电池的影响。本申请隔膜具有良好的安全效果，采用不同的无机涂层设计，隔膜的安全效果会有差异，但均好于对比例隔膜结构的安全效果。无机涂层中优选在基膜表面双面涂覆，且无机粒子越小、无机涂层越厚安全效果越好。实际可根据电池能量密度的要求和可接受的安全性能来设计无机涂层。
表3列出了隔膜中不同有机涂层的设计对锂离子电池的影响。在本申请范围的有机涂层，熔点或分解温度>200℃有机耐热树脂的有机涂层，其中有机耐热树脂含量在60％～99％范围，单层厚度0.5～5um，能表现出更佳的高温破膜效果、更好的加工性能和透气性能。
表4列出了隔膜中不同结构设计对锂离子电池的影响。不同结构的隔膜之间安全效果会有差异，但均好于对比例的安全效果。实际可根据电池能量密度的要求和可接受的安全性能来设计隔膜的结构。本申请隔膜的结构并不局限上述实施例的结构，满足本申请要求的结构均具有良好的安全效果。
表5列出了隔膜中搭配粘接层对锂离子电池的影响。粘接层可以改善电芯界面粘接和电池硬度，对提升机械性能有一定效果，但界面粘接和电池硬度也可以通过电池制备工艺来达到。本申请隔膜采用粘接层后，安全效果也均优于对比例采用粘接层的效果。
综上，本申请隔膜通过基膜、无机涂层和有机涂层的搭配，不同层之间协同作用，可同时提供良好的闭孔功能和优异的耐热性能，且闭孔温度和破膜温度之间可达到130℃，甚至可达140℃的温差，由此，本申请实施例的隔膜是一种高温下宽温程的安全隔膜。
其中，本申请所涉及的闭孔温度、破膜温度、测量时的环境温度、延伸率、收缩率、膜层厚度、颗粒粒径等具体数值，受到测量设备精度的影响，可存在一定的误差，例如可 存在1％的误差，当本申请所涉及的参数在上述误差范围内波动时，也应理解为在本申请的保护范围内。
以上，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (32)

  1. 一种隔膜，其特征在于，包括基膜、至少一层无机涂层和至少一层有机涂层，所述基膜、所述无机涂层与所述有机涂层叠层设置，且所述基膜的至少一侧表面与所述无机涂层接触，其中，所述有机涂层中有机耐热树脂的体积含量为60％～99％，有机涂层中含有无机颗粒的体积分数为1％～40％，所述有机耐热树脂的熔点或分解温度≥200℃。
  2. 根据权利要求1所述的隔膜，其特征在于，所述隔膜的破膜温度≥220℃，150℃下0.5h的热收缩率≤5％。
  3. 根据权利要求1所述的隔膜，其特征在于，所述隔膜的破膜温度≥260℃，150℃下0.5h的热收缩率≤3％。
  4. 根据权利要求1-3任一项所述的隔膜，其特征在于，所述隔膜的闭孔温度≤140℃，破膜温度≥220℃，所述隔膜的延伸率≥130％，150℃下0.5h的热收缩率≤5％。
  5. 根据权利要求1-4任一项所述的隔膜，其特征在于，每层所述无机涂层中含有无机粒子，且所述无机粒子在所述无机涂层中的体积含量>80％。
  6. 根据权利要求5所述的隔膜，其特征在于，任一层所述无机涂层中，所述无机粒子的体积含量为85％～99％。
  7. 根据权利要求5或6所述的隔膜，其特征在于，所述无机粒子的粒径D50≤2um。
  8. 根据权利要求1-7任一项所述的隔膜，其特征在于，每层所述无机涂层的厚度≤4μm。
  9. 根据权利要求8所述的隔膜，其特征在于，所述有机涂层中，所述有机耐热树脂选自芳香族聚酰胺、聚酰亚胺、聚酰胺酰亚胺、聚醚酰亚胺、聚砜、聚酮、聚醚酮或聚四氟乙烯中的至少一种。
  10. 根据权利要求9所述的隔膜，其特征在于，所述芳香族聚酰胺选自聚对苯二甲酰对苯二胺和/或聚间苯二甲酰间苯二胺。
  11. 根据权利要求1-10任一项所述的隔膜，其特征在于，每层所述有机涂层的厚度为0.5～5μm。
  12. 根据权利要求11所述的隔膜，其特征在于，每层所述有机涂层的厚度为1～4μm。
  13. 根据权利要求1-12任一项所述的隔膜，其特征在于，所述基膜的两侧表面分别设有至少一层无机涂层和至少一层有机涂层，其中，所述基膜的两侧表面均与所述无机涂层接触。
  14. 根据权利要求1-13任一项所述的隔膜，其特征在于，所述基膜的延伸率≥130％，闭孔温度≤145℃，破膜温度≥155℃。
  15. 根据权利要求14所述的隔膜，其特征在于，所述基膜的延伸率≥150％，闭孔温度≤140℃，破膜温度≥160℃。
  16. 根据权利要求1-15任一项所述的隔膜，其特征在于，所述基膜的单位厚度重量≥0.62g/m 2/μm，孔隙率<35％，平均孔径<45nm。
  17. 根据权利要求16所述的隔膜，其特征在于，所述基膜的单位厚度重量≥0.64g/m 2/μm，25％＜孔隙率<35％，平均孔径<43nm。
  18. 根据权利要求1-17任一项所述的隔膜，其特征在于，所述基膜为聚烯烃多孔膜。
  19. 根据权利要求18所述的隔膜，其特征在于，所述基膜包括第一聚烯烃树脂，所述第一聚烯烃树脂为重均分子量≥60万的超高分子量聚乙烯，且所述第一聚烯烃树脂在所述 基膜中的质量含量＞50％。
  20. 根据权利要求19所述的隔膜，其特征在于，所述基膜还包括第二聚烯烃树脂和/或第三聚烯烃树脂，其中，所述第二聚烯烃树脂的熔点＜所述第一聚烯烃树脂的熔点，所述第三聚烯烃树脂的熔点＞所述第一聚烯烃树脂的熔点。
  21. 根据权利要求20所述的隔膜，其特征在于，所述基膜中含有所述第三聚烯烃树脂，所述第三聚烯烃树脂在所述基膜中的质量含量为5％～30％。
  22. 根据权利要求21所述的隔膜，其特征在于，所述第三聚烯烃树脂选自聚丙烯、聚1-丁烯、聚1-戊烯、聚1-己烯、聚4-甲基-1-戊烯、聚1-辛烯、聚乙酸乙烯酯、聚甲基丙烯酸甲酯、聚苯乙烯、聚偏二氟乙烯或聚四氟乙烯中的至少一种。
  23. 根据权利要求1-22任一项所述的隔膜，其特征在于，所述基膜的厚度为1～16μm。
  24. 根据权利要求1-23任一项所述的隔膜，其特征在于，所述隔膜的至少一个最外表面设有粘结层。
  25. 一种如权利要求1-24任一项所述的隔膜的制备方法，其特征在于，包括：
    在所述基膜的至少一侧表面形成所述无机涂层；
    在所述基膜的另一侧表面和/或至少一层所述无机涂层的表面形成所述有机涂层。
  26. 根据权利要求25所述的制备方法，其特征在于，所述制备方法还包括：
    将基膜原料熔融混合，挤压成型后形成凝胶状片材，所述凝胶状片材依次经一次拉伸、萃取、二次拉伸和热定型后，形成所述基膜。
  27. 根据权利要求26所述的制备方法，其特征在于，所述一次拉伸包括横向拉伸和纵向拉伸，所述横向拉伸与所述纵向拉伸的拉伸比例为3-6倍。
  28. 根据权利要求26或27所述的制备方法，其特征在于，所述二次拉伸的温度为105～130℃。
  29. 根据权利要求25-28任一项所述的制备方法，其特征在于，所述在所述基膜的至少一侧表面形成所述无机涂层，包括：
    形成含有无机粒子的无机浆料，将所述无机浆料涂覆于所述基膜的至少一侧表面，经干燥后形成所述无机涂层。
  30. 根据权利要求25-29任一项所述的制备方法，其特征在于，所述在所述基膜的另一侧表面和/或至少一层所述无机涂层的表面形成所述有机涂层，包括：
    形成含有有机耐热树脂的有机浆料，将所述有机浆料涂覆于所述基膜的另一侧表面和/或至少一层所述无机涂层的表面，干燥后形成所述有机涂层。
  31. 一种二次电池，其特征在于，包括正极极片、负极极片、电解液以及如权利要求1-24任一项所述的隔膜或利用如权利要求25-30任一项所述的制备方法得到的隔膜，所述隔膜以及介于所述正极极片和所述负极极片之间，所述电解液填充于所述正极极片和所述负极极片之间且浸润所述隔膜。
  32. 一种用电设备，其特征在于，包括权利要求31所述的二次电池。
PCT/CN2022/101495 2021-06-30 2022-06-27 隔膜及其制备方法、二次电池和用电设备 Ceased WO2023274143A1 (zh)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116111286A (zh) * 2023-04-04 2023-05-12 宁德卓高新材料科技有限公司 一种改性pvdf涂覆隔膜及其制备方法及应用
CN116960575A (zh) * 2023-08-08 2023-10-27 沧州中孚新能源材料有限公司 一种高强度凝胶电解质隔膜及其制备方法和应用
CN119253200A (zh) * 2024-10-28 2025-01-03 孝感楚能新能源创新科技有限公司 一种隔膜及其制备方法、二次电池及用电装置

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113594631A (zh) * 2021-06-30 2021-11-02 华为技术有限公司 隔膜及其制备方法、二次电池和用电设备
CN116526061A (zh) * 2022-01-24 2023-08-01 华为技术有限公司 复合隔膜、电化学装置和终端设备
CN114649638B (zh) * 2022-05-20 2022-09-06 宁德卓高新材料科技有限公司 一种涂覆隔膜及其制备方法及应用
CN115764152A (zh) * 2022-10-29 2023-03-07 洛阳理工学院 一种具有聚酮涂层的锂电池隔膜
CN119330381B (zh) * 2022-12-05 2026-01-27 宁德时代新能源科技股份有限公司 氧化铝颗粒、其制备方法及隔离膜、电池和用电装置
CN116315456B (zh) * 2023-05-08 2023-08-01 合肥长阳新能源科技有限公司 一种五层共挤锂电池微孔隔膜及其制备方法
CN119786880A (zh) * 2024-12-31 2025-04-08 中材锂膜有限公司 一种涂覆隔膜及其制备方法、二次电池
CN119419445B (zh) * 2025-01-08 2025-04-04 江苏正力新能电池技术股份有限公司 隔膜及其制备方法和电池
CN120527569A (zh) * 2025-07-24 2025-08-22 中国科学院大连化学物理研究所 一种隔膜及其制备方法和电池

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104081576A (zh) * 2011-12-13 2014-10-01 科卡姆有限公司 用于锂二次电池的高耐热性复合隔膜和包括该隔膜的锂二次电池
JP2018170215A (ja) * 2017-03-30 2018-11-01 三菱製紙株式会社 リチウムイオン電池セパレータ
CN111416086A (zh) * 2020-03-04 2020-07-14 华为技术有限公司 电池隔膜及其制备方法、电池和终端
WO2021131534A1 (ja) * 2019-12-27 2021-07-01 パナソニックＩｐマネジメント株式会社 リチウム二次電池
CN113594631A (zh) * 2021-06-30 2021-11-02 华为技术有限公司 隔膜及其制备方法、二次电池和用电设备

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010195898A (ja) * 2009-02-24 2010-09-09 Sumitomo Chemical Co Ltd ポリオレフィン系樹脂組成物、該組成物を用いた多孔質フィルムの製造方法、多孔質フィルム、積層多孔質フィルムの製造方法、積層多孔質フィルムおよび電池用セパレータ
JP5617609B2 (ja) * 2010-12-24 2014-11-05 宇部興産株式会社 電池用セパレータおよびそれを用いた二次電池
CN102394282B (zh) * 2011-11-25 2014-12-10 佛山市金辉高科光电材料有限公司 一种锂离子二次电池多孔多层隔膜及其制造方法
CN105140450A (zh) * 2015-09-17 2015-12-09 中航锂电（洛阳）有限公司 一种锂离子电池复合隔膜及其制备方法、锂离子电池
CN106252571A (zh) * 2016-08-31 2016-12-21 乐凯胶片股份有限公司 一种用于锂离子电池的多层多孔隔膜
CN113614993A (zh) * 2019-03-28 2021-11-05 东丽株式会社 聚烯烃微多孔膜、二次电池用隔板及二次电池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104081576A (zh) * 2011-12-13 2014-10-01 科卡姆有限公司 用于锂二次电池的高耐热性复合隔膜和包括该隔膜的锂二次电池
JP2018170215A (ja) * 2017-03-30 2018-11-01 三菱製紙株式会社 リチウムイオン電池セパレータ
WO2021131534A1 (ja) * 2019-12-27 2021-07-01 パナソニックＩｐマネジメント株式会社 リチウム二次電池
CN111416086A (zh) * 2020-03-04 2020-07-14 华为技术有限公司 电池隔膜及其制备方法、电池和终端
CN113594631A (zh) * 2021-06-30 2021-11-02 华为技术有限公司 隔膜及其制备方法、二次电池和用电设备

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP4354629A4 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116111286A (zh) * 2023-04-04 2023-05-12 宁德卓高新材料科技有限公司 一种改性pvdf涂覆隔膜及其制备方法及应用
CN116111286B (zh) * 2023-04-04 2023-08-18 宁德卓高新材料科技有限公司 一种改性pvdf涂覆隔膜及其制备方法及应用
CN116960575A (zh) * 2023-08-08 2023-10-27 沧州中孚新能源材料有限公司 一种高强度凝胶电解质隔膜及其制备方法和应用
CN119253200A (zh) * 2024-10-28 2025-01-03 孝感楚能新能源创新科技有限公司 一种隔膜及其制备方法、二次电池及用电装置

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