WO2012142802A1 - 后交联橡胶、聚烯烃复合材料纳米微多孔隔膜及其制造方法 - Google Patents

后交联橡胶、聚烯烃复合材料纳米微多孔隔膜及其制造方法 Download PDF

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WO2012142802A1
WO2012142802A1 PCT/CN2011/077483 CN2011077483W WO2012142802A1 WO 2012142802 A1 WO2012142802 A1 WO 2012142802A1 CN 2011077483 W CN2011077483 W CN 2011077483W WO 2012142802 A1 WO2012142802 A1 WO 2012142802A1
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Prior art keywords
rubber
polyolefin
temperature
membrane
microporous
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PCT/CN2011/077483
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English (en)
French (fr)
Inventor
李鑫
李建华
陈卫
焦永军
李龙
邓新建
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天津东皋膜技术有限公司
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Priority to US14/442,098 priority Critical patent/US9991494B2/en
Publication of WO2012142802A1 publication Critical patent/WO2012142802A1/zh

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H01M50/406—Moulding; Embossing; Cutting
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/494—Tensile strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/10—Batteries
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L21/00—Compositions of unspecified rubbers
    • 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 invention relates to a nano-scale microporous membrane for a lithium ion battery using a post-crosslinked rubber modified polyolefin and a manufacturing method thereof, in particular to a rubber for a lithium ion power battery or an energy storage battery with high safety and long cycle life.
  • Polyolefin composite microporous separator
  • the polyolefin microporous membrane has three-dimensional network-like nanoporous pores (average pore diameter of less than 200 nm), is resistant to high voltage oxidation, and is stable to organic electrolytes of lithium ion batteries.
  • As a separator material it has been widely used in mobile phones and notebook computers. Ion batteries, typical commercial polyolefin microporous membranes are "dry” PP/PE/PP three-layer composite separators, single-layer “wet” high molecular weight PE separators (porosity 30-65%, conventional thickness 16, 20, 25, 30 microns).
  • the diaphragm has insufficient toughness and is easy to tear in the transverse direction;
  • the intermediate microporous layer uses PE which is turned off at a high temperature of 135-145 ° C
  • the PP microporous layer having a limited melting point and being thermally stretched and strengthened has a large heat shrinkage at a high temperature of 130 ° C or higher. Disadvantages of high temperature membrane breakage;
  • the thickness direction lacks compressive elasticity and stress absorption capability.
  • the Chinese invention patent application 02152444. 0 proposes blending less than 10% of the thermoplastic polyolefin elastomer in the polyolefin matrix. (2-ethylene propylene rubber, EPDM rubber), and then stretched into holes; however, the nature of the thermoplastic polyolefin elastomer determines its influence on the formation and distribution of silver streaks in the polyolefin matrix during cold drawing, that is, the effect The ability of the polyolefin matrix to "dry" into pores does not result in a suitable porosity. Therefore, the proportion of the thermoplastic olefin elastomer to be incorporated must be low, so that the elastic properties of the separator are limited and the practicality is insufficient.
  • Process. The structure of PP/PE/PP is formed, wherein the middle PE layer can function as a high temperature shutdown.
  • the above patents only provide the manufacturing technology of the thermal shutdown diaphragm, and the cycle life of the diaphragm to the lithium ion power battery.
  • Technical solutions were not provided for improvement in reliability.
  • the other is the "wet process”, the “wet process”, also known as the thermally induced phase separation process, which combines high molecular weight polyolefin resins with “high temperature compatibilizers” (high boiling hydrocarbons such as paraffin oil, or Other ester plasticizers, the solvent and the polyolefin are mutually dissolved in a thermodynamically high temperature, and can achieve molecular level mixing.
  • high temperature compatibilizer which is actually a process solvent) mixing.
  • the high-temperature melt which is heated and kneaded is rapidly solidified on the surface of the chill roll, phase separation occurs during the cooling process, and the sheet is stretch-strengthened by stepwise biaxial stretching or simultaneous biaxial stretching, and then the volatile cleaning solvent is used.
  • the "high-temperature compatibilizer" in the semi-finished membrane is extracted, and the nano-scale microporous membrane material which is interpenetrated internally by further heat-stretching strengthening, heat setting and cooling can be prepared.
  • the common method is a single-layer PE membrane, and dry Compared with the diaphragm, the two-way tensile strengthening, the viscosity average molecular weight of the raw material is generally more than 500,000, and the wet film has improved tensile strength and elongation at break.
  • the main disadvantages of the "wet method" diaphragm include:
  • the thickness direction is also elastic and lacks stress absorption capability, and can not meet the high-end requirements of the power battery in terms of safety and cycle life of the battery.
  • porous physical gel membrane which is a lyotropic phase separation method.
  • a typical PVDF-HFP copolymer porous gel membrane manufactured by the Bel lcore process (belongs to a physical gel, in a solvent such as acetone). The film is also dissolved.), and the cell is bonded to the pole piece by a hot pressing process. The cell cycle life is high.
  • the PVDF-HFP copolymer gel membrane pore size is slightly larger, close to 0.
  • the diaphragm has not been subjected to hot tensile strengthening, low mechanical strength, poor tensile strength, very small elastic modulus in the plane direction, and cannot be adapted to the process requirements of battery winding; even if a laminated process is used to prevent short circuit of the battery It is also required to increase the thickness of the separator (usually designed to have a thickness of 40-60 ⁇ m) to compensate for the lack of strength.
  • the thickness of the separator is large, the electrolyte resistance between the positive and negative electrodes is large, and the characteristics of the rate and energy density of the battery are both unfavorable.
  • diaphragms are required to have the following characteristics:
  • the diaphragm When the internal accidental heating of the battery is at a high temperature of 130-200 ° C, the diaphragm should have a melt-off characteristic and a small heat shrinkage; high temperature breakage, even mechanical stability after melting;
  • the thickness direction has good compressive elasticity, that is, when the compressive stress is applied in the thickness direction, the diaphragm has appropriate elastic deformation ability to meet the needs of the expansion of the negative electrode, and the pole piece is prevented from being subjected to uneven compressive stress. Stable deformation and buckling; compression deformation without causing a decrease in porosity, even microporous closure, affecting the normal discharge of the battery; elastic recovery after pressure release, ensuring uniform and close contact between the positive and negative plates and the diaphragm, There is no local lean liquid.
  • Chinese invention patent application 200880003493. 7, 200880000072. 9 reported the use of a binder to coat alumina on the surface of the polyolefin microporous membrane.
  • a composite membrane technical solution in which ceramic micropowders are connected into a porous coating Chinese invention patent application 200510086061. 5 reports on the surface of a polyolefin microporous membrane using a polyamide having a high melting point of 180 ° C or higher, polyamideimide, polyacryl A technical solution for forming a porous coating layer such as an amine; Chinese Patent Application No. 200480034190.
  • the existing polyolefin separator is basically an inert material, the adhesion between the coating and the coating is insufficient, the coating is thick and easy to peel off, and the heat shrinkage effect of the polyolefin membrane is not obvious;
  • the colloid and its slurry in the slurry will enter the micropores of the polyolefin membrane during the implementation of the above coating scheme, which may affect the membrane after the solvent is evaporated and dried to form a membrane.
  • the pore size distribution and gas permeability, the consistency of the coating method for mass production is difficult to control, and the coating method composite membrane is expensive to manufacture.
  • Chinese Patent Application No. 0112218. 8 proposes mixing a monomer polymer which can be thermally crosslinked to form a gel in an electrolyte.
  • the gel is used to increase the bonding strength between the separator and the positive electrode tab.
  • the gel forms a gel in the micropores of the separator during the thermal crosslinking formation, thereby affecting the separation.
  • the permeability of the membrane, and the monomer with incomplete reaction may also oxidize on the positive electrode side, produce gas, etc., and even affect the cycle performance of the battery.
  • the safety is easy to fail; usually the battery is used before the injection of liquid to 85-9CTC
  • the normal use temperature is between -1 (T + 60 ° C), so the diaphragm is required to adapt to the compression and elastic properties under normal charge and discharge conditions in this temperature range.
  • the "wet method" polyolefin composite membrane is also reported by the co-extrusion process.
  • the Chinese invention patent application 200680035668. 3, 200780005795. 3 , 200510029794. 5 etc. mainly adopts the adjustment of the solid content of the inter-layer polyolefin raw material.
  • the co-extrusion composite membrane is improved by the method of different raw material ratio of polyethylene/polypropylene and the method of controlling the molecular weight of different membrane raw materials to obtain different porosity and pore size distribution between layers and different melting points between membrane layers.
  • the high temperature membrane rupture temperature and compression resistance of the separator and the elastic properties are still insufficient.
  • Rubber/plastic blended polyolefin thermoplastic elastomer dense materials are dynamically vulcanized.
  • the classic materials are PP/EPDM, PE/PSBR, PE/EPDM, etc.
  • the dynamic vulcanization process is generally in the material blending process.
  • the rubber phase is dynamically cross-linked by cross-linking agent, and melt-sheared and dynamically cross-linked.
  • the microstructure of the cooled material is in a "sea-island" structure, the plastic phase is a continuous phase, and the rubber phase is distributed in an island shape.
  • the particle size of the rubber phase is on the order of micron or even one hundred micron, and almost no submicron or nanometer distribution effect can be achieved.
  • the safety and service life of lithium ion batteries are related to the battery separator materials.
  • 201110055620.1 proposes a technical route using a nano-pre-crosslinked rubber micropowder modified co-extruded composite separator and a lithium ion battery using the same, wherein the rubber micropowder raw material is a pre-crosslinked physical and chemical state, and the primary particle is nanometer Particle size, but there is a problem of agglomeration peculiar to nano-powder.
  • the particle size of the secondary particles after agglomeration is about 5-50 microns, which is difficult to uniformly distribute in the matrix of the polyolefin microporous membrane, and it is difficult to obtain high thickness precision ( Diameter products with uniform distribution of microstructure and mechanical properties; ⁇ nano-rubber powders are costly.
  • the inventors made the raw materials and process methods for the separator.
  • the new design and adjustment can achieve a highly elastic rubber material evenly dispersed in the polyolefin nanoporous matrix, and obtain a polyolefin which has the aforementioned characteristics and can improve the safety performance and cycle performance of the lithium ion battery.
  • the microporous membrane compensates for various deficiencies in the prior art, and the following invention is specifically proposed.
  • the microporous membrane of the invention comprises at least a layer of nano microporous membrane A having a chemical gel content of more than 20%, and the microstructure thereof is designed to uniformly disperse the rubber material in the polyolefin nanofibrous matrix through post-crosslinking treatment to form an oak.
  • microporous membrane can be a single layer A, more preferably complex
  • the membrane A/B double-layer structure, another layer of nano-microporous membrane B is designed as a polyolefin plastic body, wherein the rubber content is less than 20%; the microporous membrane has the following characteristics:
  • the total thickness is in the range of 8-40 microns, preferably 10-36 microns, the average pore diameter is less than 150 nanometers, the porosity is between 35-70%, and the Gurley value is between 50-500S/100CC;
  • Liquid swell and compression elasticity at 30 ° C, the membrane absorbs DMC liquid in a free state for 1 hour and then increases in thickness to (1. 05-1. 30) times before aspiration, after aspiration
  • the diaphragm is applied with a static compressive stress of 0.35 MPa in the thickness direction and held for 5 minutes, the compressive deformation of the diaphragm in the thickness direction is greater than 5% of the thickness before compression, less than 25%, and the thickness of the test diaphragm is restored to compression after 5 minutes of pressure release. More than 85% of the previous;
  • the longitudinal tensile strength of the separator is between 50_200MPa, the elastic modulus is greater than 800MPa, and the longitudinal elongation at break is greater than 30%; the transverse tensile strength is between 30_150MPa, the elastic modulus is greater than 300MPa, and the transverse elongation at break is greater than 50%.
  • the needling strength is greater than 300gf / 20 microns,
  • the diaphragm of the present invention is preferably designed to have a double-layer A/B or three-layer A/B/A function in the thickness direction from the requirements of high strength, thermal shutdown, high temperature resistance, compression elasticity and the like of the lithium ion power battery separator.
  • the complementary composite microporous membrane structure more economical, is preferably a two-layer coextrusion process.
  • the B layer is designed as a polyolefin plastic body with a rubber content of less than 20%. Its main purpose is to provide high strength and high temperature thermal shutdown characteristics for the composite separator; at least one of the microporous membranes is designed to have a high rubber content.
  • Nano-microporous separator raw rubber raw materials before cross-linking, especially low-molecular-weight liquid Body rubber or low crystallinity rubber which is a waxy solid at room temperature.
  • Such raw rubber can be conveniently mixed with a high temperature compatibilizer at 70-11 CTC to form a viscous fluid with a viscosity between the two.
  • the viscous fluid is at 90.
  • the dynamic viscosity at -110 °C is controlled at l-50Pa'S, which can be conveniently metered and fed into a mixing machine such as a twin-screw extruder;
  • the polyolefin plastic material can be in the form of pellets or powders, preferably Powder, which can be easily mixed with high-temperature compatibilizer and liquid rubber to form a uniform slurry and then fed to the extruder; it is kneaded with polyolefin plastic matrix at 170-22CTC to form a thermodynamic solution, which is quenched by quenching.
  • the sheet After the sheet is filmed, the sheet is hot-stretched, and the polyolefin plastic matrix in the sheet is microfibrillated and networked, and the physical form change of the distributed high-temperature compatibilizer and liquid rubber composition is combined with the microfiber composite. They are subjected to hot-stretching and deformation together, so that the "rubber/plastic" is uniformly distributed on the microscopic first, and then cross-linked by electron beam irradiation. The high elasticity of the rubber after cross-linking can compensate the elasticity of the polyolefin matrix.
  • the foot mainly provides compressive elasticity and high temperature film rupture resistance, and inhibits heat shrinkage of polyolefin solids and even melt at high temperature, thereby preventing short circuit of positive and negative electrode sheets, thereby improving the safety and service life of the lithium ion battery. .
  • the rubber raw material adopts an unvulcanized liquid rubber with a weight average molecular weight of 30,000-80,000 at 60 °C, a Brookfield Viscosity (7 ft rotor) at 50-1500 Pa's, a chemical gel content of less than 10%, and good compatibility with polyolefin. Low crystallinity rubber with waxy solid at room temperature (viscous flow above 60 °C).
  • Rubber raw materials include EMG, EDM, EPDM, ethylene-acrylate rubber, or Diolefin rubber: polyisoprene rubber IR, butadiene rubber BR, weakly polar butyl nitrile rubber NBR having a acrylonitrile content of 20% or less, styrene-butadiene rubber SBR having a styrene content of 20% or less, or the like
  • the ethylene/propylene mass ratio is between (50: 50 ) - ( 85: 15), wherein a suitably high proportion of ethylene contributes to the crosslinking of the radiation, and the propylene segment in the polymer backbone is substantially free of radiation crosslinking due
  • the third monomer includes A3. Basenorbornene (ENB), 1, 4-hexadiene (HD), dicyclopentadiene DCPD, preferably 3-12% by mass of the third monomer in the EPDM for facilitating irradiation crosslinking.
  • the polyolefin plastic material is selected from the group consisting of high-density polyethylene HDPE, polypropylene PP, polybutene PB, linear low-density polyethylene LLDPE, and the like, or a copolymer of ethylene, propylene or butene or a copolymer with an alpha olefin or a combination thereof.
  • the microporous membrane is easy to stretch and strengthen, is not easy to break the membrane, and the shutdown temperature is controlled at 130-145 ° C, preferably a high-density polyethylene having a weight average molecular weight of 500,000 or more, and more preferably a weight average molecular weight of 1 to 3,000,000.
  • Ultra-high molecular weight polyethylene in order to improve the compatibility of polyethylene and rubber, and improve the adhesion between the separator and the battery pole piece, polyethylene-MAH-PE and ultra-high molecular weight polyethylene modified by maleic anhydride grafting can be used.
  • the composition of UHMWPE is used together as a raw material for the polyolefin, and preferably the weight percentage of MAH-PE in the polyolefin plastic raw material is 10% or more.
  • the high temperature compatibilizer is selected from paraffin oil or dioctyl terephthalate DT0P, dioctyl sebacate D0S, diisodecyl phthalate DINP, diisodecyl phthalate DIDP and other high boiling point, low molecular weight.
  • An ester plasticizer (relative molecular weight of 600 or less) or a low dynamic viscosity (0.2 Pa's or less) or a composition thereof.
  • the nano-porous membrane of the "interpenetrating network" of the rubber/plastic composite material is prepared by the thermal synthesis of the above main raw materials by the combination of biaxial stretching strengthening, extraction, irradiation crosslinking and the like, the main process steps and the main process steps thereof
  • the design ideas continue to be explained as follows: (1) Blending, mixing and casting of the ingredients, firstly mechanically mixing the raw materials of polyolefin micron powder, high temperature compatibilizer, liquid rubber or waxy rubber, antioxidant, etc. at 70-110 °C. It is slurried and swelled for 8-24 hours. After stable metering, it is conveyed into a continuous mixing equipment such as a twin-screw extruder.
  • the above raw materials are kneaded into a thermodynamically homogeneous solution at a high temperature of 170-220 ° C.
  • the uniform high-temperature melt is extruded through a die and continuously solidified and phase-separated on the surface of the metal roll to obtain a "gelatin semi-finished sheet A" in a physical gel state, wherein the easily crystallized polyolefin is used as a three-dimensional skeleton material.
  • the jelly semi-finished sheet A" provides strength and sufficient stiffness for subsequent biaxial stretching; the crystallization of the polyolefin remains substantially in the physical state of fine platelets or spherulites, while the high temperature compatibilizer, rubber mixture The viscous fluid is highly dispersed in the "gelatin semi-finished sheet A".
  • the composition of the rubber and the high temperature phase solvent distributed between the polyolefin platelets or spherulites has a low viscosity viscosity, which can follow the plastic deformation, flow, filling, and Therefore, it is uniformly dispersed and distributed in the three-dimensional network skeleton of polyolefin microfibers formed after hot stretching to form a "composite film semi-finished product B" after stretching and strengthening; hot stretching temperature: 105-130 ° C, hot stretching ratio MD1 Between 3-7, TD1 is between 3_7; biaxial stretching can be step stretching or synchronous biaxial stretching, preferably longitudinal stretching stable simultaneous stretching process.
  • the viscosity of the rubber polymer is large, the Brownian motion is weak, and the extraction is basically non-existent. Shearing and stretching mechanical action, the rubber polymer is not easy to unwind, and the rubber component may undergo partial thermal crosslinking after undergoing hot processing such as 170-22CTC high-temperature mixing and hot stretching.
  • the pore size of the microporous membrane becomes smaller, and the thickness and width are appropriately shrunk due to the surface tension. It is preferred to use the "polyolefin/rubber interpenetrating network semi-finished microporous membrane C2" after extraction.
  • the two-time hot drawing and heat setting process continued to adjust the pore size, porosity, thickness and other indexes of the microporous membrane to obtain a "polyolefin/rubber interpenetrating network near-finished microporous membrane D".
  • Too low radiation dose rubber is insufficiently cross-linked, and too high a dose tends to cause degradation of the polyolefin; after the aforementioned processing steps (1), (2), (3), wherein the thermoplastic rubber component remains in the polymerization
  • the olefin microfiber network has been evenly distributed.
  • the main purpose of irradiation is to cause "in situ" irradiation crosslinking of rubber components to form a polymer network and improve elasticity.
  • polyolefin is preferred as high density polyethylene HDPE
  • the polymer PE of the entangled amorphous region of the polyethylene microfiber network also undergoes partial irradiation crosslinking, thereby also improving the creep resistance and microporation of the microporous separator under long-term compression conditions in the battery.
  • a partial grafting reaction may also occur between the polyolefin microfibers and the liquid rubber in contact therewith.
  • the irradiation crosslinking step can also be carried out in a state of no pores before the aforementioned extraction step (3), so that there is no need to worry about the negative influence of oxygen present in the porous material during irradiation, and the process of the first irradiation after extraction
  • the basic process is as follows: The following process steps are applied to the "gelatin semi-finished sheet A" after casting: hot calendering, two-way hot stretching strengthening, on-line electron beam irradiation crosslinking, low temperature extraction, second hot stretching, heat After the pre-heating of the "finished semi-finished sheet A" is carried out, the calendering is strengthened in the thickness direction, and the thickness rolling ratio is controlled to be 1-2.
  • the hot drawing temperature 105-130 ° C
  • the thermal stretching ratio MD1 is between 3-7
  • TD1 is between 3_7
  • the double-drawn film is cross-linked by electron beam on-line irradiation, the irradiation dose is 50_250KGy
  • low temperature extraction using terpene hydrocarbon or The extraction solvent such as halogenated anthracene hydrocarbon is selectively extracted from the high-temperature phase solvent component in the semi-finished film at a temperature of T55 ° C under normal pressure or 2-7 MPa high pressure to obtain a polyolefin having no near high temperature compatibilizer.
  • the semi-finished microporous membrane C1 adopts the second hot stretching and heat setting to continuously adjust the pore diameter, porosity, thickness and the like of the microporous membrane, and after cooling and winding, the post-crosslinked rubber and the polyolefin composite nano microporous membrane are obtained.
  • This process of pre-irradiation extraction must control the "rubber/plastic ratio" of the raw material, and should reduce the "rubber/plastic ratio” in the separator material to (40: 60) at the expense of appropriately reducing the compressive elasticity of the separator.
  • the crosslinked rubber and the polyolefin microfiber network form a weaker "interpenetrating" structure, or a substantially “island/sea” discontinuous rubber distribution structure, when the rubber phase is a uniform, dense island.
  • the polyolefin microfiber network matrix When inlaid and distributed in the polyolefin microfiber network matrix, it can follow and adapt to the plastic deformation of the polyolefin microfiber network matrix during the second hot stretching after extraction, and the film after the second thermal stretching. Wrinkles occur; while the film with high "rubber/plastic ratio” and “strong interpenetrating" after irradiation cross-linking is inconvenient to continue to adopt the planar two-way hot stretching process.
  • the porosity, pore size, thickness and other technical indexes of the microporous membrane because the rubber component increases its cross-linking degree and its elasticity rises sharply, and the plasticity drops sharply.
  • the network-like interconnected rubber will contribute a certain high elasticity to the film in the plane direction. It is easy to cause buckling of the diaphragm after 2 times of hot stretching.
  • the composite membrane is manufactured by a co-extrusion processing method, and the co-extruded composite membrane has a simple production process and a low production cost compared with the various coating methods described above, and polyethylene or polyolefin in the A/B two-layer semi-finished product during co-extrusion processing.
  • the high-temperature melt has a certain intertwining effect at the interface, which can ensure high bonding strength/peeling strength between the two layers.
  • the peel strength of lOgf/cm or more between the A/B layers can be more effectively utilized by the A layer having a high rubber content.
  • the heat shrinkage of the B layer mainly composed of polyethylene at a high temperature is suppressed.
  • the appropriate pore size and porosity of the co-extruded composite membrane are integrated in the Gurley value of the gas permeability index.
  • the excessive Gurley value means that the membrane pore resistance is large, the membrane permeability is poor, especially the permeability after compression is worse, the battery capacity.
  • the initial low Gurley value means that the diaphragm has a large pore size or a large pore size or a high porosity, the battery is easily self-discharged too fast or short-circuited, and the safety is not good. Therefore, the co-extruded composite membrane of the present invention is preferably at room temperature.
  • the lower Gurley value is 50_500S/100CC, preferably the separator has an average pore diameter of less than 200 nm, and more preferably the separator has an average pore diameter of less than 150 nm.
  • the embodiment of the present invention will be described in detail. Further, the present invention is not limited to the embodiments described below, and various modifications can be made within the scope of the invention.
  • the test was carried out using a CHY-C2 thickness gauge manufactured by Jinan Languang Electromechanical Technology Co., Ltd., and a 50 mm ⁇ 50 mm sample was cut from the porous film, and a 5-point measurement was performed uniformly on the surface of the sample with a thickness gauge, and then the film thickness was measured. The values are averaged.
  • microporous membrane was tested for gas permeability in accordance with JIS P8117.
  • the measuring instrument was tested by MTS's CMT4000 electronic tester.
  • the maximum load of the needle with a spherical surface (curvature radius R: 0.5 mm) and a diameter of 1 was measured at a speed of 2 mm/s. .
  • the pore size distribution and average pore diameter of the separator were tested using a mercury intrusion gauge at a pressure of 20-2000 psi.
  • g/cm 3 membrane weight / (thickness * area), divided by the theoretical value of 94 g/cm 3 , is considered to be the porosity of the microporous membrane.
  • the solution was firstly soaked in dimethyl carbonate DMC at 30 ° C for 1 hour to test the thickness before and after pipetting; then the film was pressed and held for 5 minutes in the thickness direction with a compressive stress of 0.35 MPa, using a film thickness tester. The thickness before and after pressing was measured.
  • the diaphragm was pressed in the middle of the glass plate, and a static compressive stress of 0.135 MPa was applied in the thickness direction.
  • the film was heated at a rate of 1 ° C/min from 90-145 ° C, held at 145 ° C for 5 minutes, and then cooled to room temperature.
  • Gurley value greater than 2000S/100CC is considered as thermal shutdown temperature less than 145 ° C; from 90 to 200 ° C to the diaphragm at a rate of 1 ° C / min, to 200 ° C for 5 minutes, then cooled to room temperature, test
  • Gurley value and the observed physical morphology of the membrane after cooling remain intact.
  • a layer formula ultra-high molecular weight polyethylene (UHMWPE) IO parts with a weight average molecular weight (Mw) of 2.5 million; 15 parts of maleic anhydride grafted high density polyethylene with a weight average molecular weight of 350,000; weight average molecular weight 42000, 60 ° C Lower Brookfield viscosity 800Pa*S, ethylene/propylene mass ratio 75/25, third elastomer ENB content 10.5% liquid EPDM (Trilene 77) 10 parts, dioctyl sebacate (DOS) : 65 parts; antioxidant 1010: 0.3 parts;
  • Ultra-high molecular weight polyethylene UHMWPE IO parts with a weight average molecular weight (Mw) of 2.5 million; 15 parts of maleic anhydride grafted high density polyethylene with a weight average molecular weight of 350,000; Brookfield at 60 °C Viscosity 800Pa*S, ethylene/propylene mass ratio 75/25, third elastomer ENB content 10.5% liquid EPDM rubber 5 parts, dioctyl sebacate (DOS): 70 Parts; Antioxidant 1010: 0.3 parts.
  • UHMWPE Ultra-high molecular weight polyethylene
  • the separation pressure is 1. 5-1
  • the cleaning pressure is: 1. 0MPa
  • the separation pressure is 1. 5-1
  • the separation pressure is 1. 5-1
  • the separation pressure is 1. 5-1 8MPa
  • the separation temperature is 65 ° C
  • the extraction solvent is circulated throughout the system to clean the product;
  • the hot-rolling temperature of the semi-finished film is 1. 5 times, the transverse hot drawing is 1. 3 times, the hot drawing temperature is 125°. C ;
  • the thickness of the coextruded composite membrane was 23 ⁇ m, and the thickness of the coextruded composite membrane was tested after the pressure was released for 5 minutes. At 24 microns, the membrane remained compressively elastic after 2000 cycles of compression/release, and the thickness of the coextruded composite membrane was tested to be 22 microns after 5 minutes of pressure release.
  • the co-extruded composite membrane was firstly soaked in dimethyl carbonate DMC at a temperature of 30 ° C for 1 hour, and the thickness after the aspiration was 30 ⁇ m; the co-extruded composite membrane after the aspiration was applied in the thickness direction of 0.35 After MPa static compressive stress and held for 5 minutes, the thickness of the co-extruded composite membrane was 28 ⁇ m, and the thickness of the co-extruded composite membrane was tested to be 29 ⁇ m after 5 minutes of pressure release, so that the compression/release cycle under the aspiration state was 2000 times. The thickness of the coextruded composite membrane was tested to be 25 microns after still maintaining compressive elasticity and pressure release for 5 minutes.
  • the pressure-compressed composite separator was applied at a temperature of 145 ° C in the thickness direction by a static compressive stress of 0. 35 MPa and kept for 60 minutes and then cooled to room temperature.
  • the separator remained intact and its thermal shrinkage in both the longitudinal and transverse directions was less than 8%; the Gurley value was greater than 2000S/100CC.
  • the composite separator is used, the A side thereof is in contact with the negative electrode tab of the battery, the B side is in contact with the positive electrode tab of the battery, and the pole group is pressurized at 95 ° C / l MPa for 15 min before the liquid injection, and the electrolyte is injected after drying.
  • Made into a lithium-ion battery tested 150 ° C hot box, acupuncture, short circuit, 1C cycle at room temperature 25 ° C, battery safety test all qualified, cycle life: 2350 times.
  • the battery was fabricated in the same manner as in Example 1.
  • the diaphragm was made of a company's dry PP/PE/PP film, thickness 25 ⁇ m, porosity 40%, Gurley value 600-630S/100CC, tensile strength: MD direction 165MPa, TD direction 13MPa
  • the transverse elongation at break is 12%.
  • the thickness of the coextruded composite membrane was 23.5 ⁇ m, and the thickness of the test membrane was still 23.5 ⁇ m after 5 minutes of pressure release.
  • Elastic recovery ability; after the compression/release cycle 50 times, the thickness of the separator was 23 ⁇ m, and the test was stopped.
  • the battery was fabricated in the same manner as in Example 1.
  • the diaphragm was made of a company's wet single-layer PE separator, thickness 25 ⁇ m, porosity 49%, Gurley value 95S/100CC, tensile strength: MD direction 143 MPa, TD direction 21 MPa, longitudinal fracture extension The growth rate is 42% and the transverse elongation at break is 344%.
  • the thickness of the coextruded composite membrane was 23 ⁇ m, and the thickness of the test membrane was still 23 ⁇ m after 5 minutes of pressure release.
  • the thickness is 22 microns, stop the test

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Abstract

本发明涉及采用后交联橡胶改性聚烯烃的锂离子电池用复合材料纳米微多孔膜及其制造方法，微多孔膜至少包括一层化学凝胶含量20%以上的纳米微多孔膜A层，其微观结构设计为聚烯烃纳米微纤基体中均匀弥散经过后交联处理的橡胶材料，形成橡、塑复合材料纳米微多孔隔膜，具备高强度、热关断、耐高温、良好的吸液溶胀及压缩弹性，可应用于高安全性、长循环寿命的锂离子动力电池。

Description

后交联橡胶、 聚烯烃复合材料纳米微多孔隔膜及其制造方法 技术领域
本发明涉及采用后交联橡胶改性聚烯烃的锂离子电池用纳米级微多孔 隔膜及其制造方法， 尤其涉及应用于高安全性、 长循环寿命的锂离子动力电 池或储能电池的橡胶、 聚烯烃复合材料微多孔隔膜。
背景技术
聚烯烃微多孔膜具有贯穿的三维网络状纳米级微孔 （平均孔径小于 200 纳米） ，耐高电压氧化、 对锂离子电池的有机电解质稳定， 作为隔膜材料目 前已广泛应用于手机、 笔记本电脑锂离子电池， 典型的商品化聚烯烃微多孔 隔膜为 "干法" PP/PE/PP三层复合隔膜、单层 "湿法"高分子量 PE隔膜（孔 隙率 30-65%、 常规厚度为 16、 20、 25、 30微米）。
现有聚烯烃微多孔隔膜在安全性和电池的循环寿命等方面目前均满足 不了动力电池的高端要求，主要技术分析如下：
现有 "干法" PP/PE/PP三层隔膜的主要缺点是：
1. 隔膜的强韧性不足， 横向易撕裂；
2. 虽然中间微多孔层采用了 135-145°C高温下关断的 PE，但是熔点有限 并经过热拉伸强化的 PP微多孔层在 130°C以上的高温下仍存在热收 缩偏大、 高温破膜的缺点；
3.厚度方向缺乏压缩弹性和应力吸收能力。
为提高 "干法 " PP/PE/PP 隔膜的横向抗撕裂性能， 中国发明专利申请 02152444. 0 提出了在聚烯烃基体中共混入低于 10%的热塑性聚烯烃弹性体 (二元乙丙橡胶、 三元乙丙橡胶）， 然后再拉伸成孔的方法； 但是热塑性聚 烯烃弹性体的本性决定了其影响冷拉时聚烯烃基体中银纹的形成和分布， 即 影响聚烯烃基体 "干法"拉伸成孔的能力， 得不到合适的孔隙率， 因此其中 热塑性烯烃弹性体混入的比例必须低， 所以对隔膜的弹性性能提高有限， 实 用性不足。
美国专利 No. 4， 650， 730和 4， 431， 304， 5， 691， 077等都提及多层隔 膜结构，有的采用管型聚丙烯薄膜自身压扁工艺，有的采用多层膜复合工艺。 形成了 PP/PE/PP的结构， 其中中间的 PE层可以起到高温关断的功能， 上述 几项专利仅仅提供了热关断隔膜的制造技术， 而对隔膜对锂离子动力电池的 循环寿命和可靠性的改善方面未提供技术解决方案。
另外一种是 "湿法"工艺， "湿法"又称热致相分离法， 将高分子量的 聚烯烃树脂与 "高温相容剂" （高沸点的垸烃类液体， 如石蜡油， 或其他酯 类增塑剂， 该溶剂与聚烯烃在高温下在热力学意义上相互溶解， 可以达到分 子级别的混合， 本发明定义其为 "高温相容剂"，其实也是一种工艺溶剂） 混合， 加热混炼均匀的高温熔体在冷辊表面快速凝固， 降温过程中发生相分 离， 再以分步双向拉伸或同步双向拉伸对薄片做拉伸强化处理， 然后用易挥 发的清洗溶剂去萃取半成品膜片中的 "高温相容剂"， 经进一步热拉伸强化、 热定型、 冷却可制备出内部相互贯通的纳米级微孔隔膜材料， 该法常见的为 单层 PE隔膜， 与干法隔膜相比， 由于采用双向拉伸强化、 原料的粘均分子 量一般在 50万以上， 湿法隔膜在横向拉伸强度和断裂伸长率均有所提高， 现有 "湿法" 隔膜主要缺点包括：
1.与干法相比，必须采用溶剂萃取工艺， 生产成本略高； 2. 130°C以上高温下热收缩偏大；
3. 130°C以上高温下耐高温破膜能力不足；
4.厚度方向同样弹性缺乏应力吸收能力， 在安全性和电池的循环寿命 等方面均满足不了动力电池的高端要求。
除聚烯烃微孔隔膜外还有一种是溶致相分离法的多孔物理凝胶隔膜，典 型的如 Bel lcore工艺制造的 PVDF-HFP共聚物多孔凝胶隔膜 (属于物理凝胶， 在丙酮等溶剂中还会溶解)，使用时与极片间通过热压工艺粘结成为一个整 体极组， 电池循环寿命较高；但是 PVDF-HFP共聚物凝胶隔膜微孔孔径略大， 接近 0. 5-2微米;隔膜未有经过热拉伸强化、 机械强度低， 拉伸强度较差，平 面方向的弹性模量非常小，不能适应电池卷绕等工艺要求；即使采用叠片工 艺，为防止电池短路，也要求提高隔膜的厚度 （通常厚度设计为 40-60微米） 以弥补其强度的不足， 隔膜厚度大、 则正负极间的电解液电阻大、 对电池的 倍率特性和能量密度等特性均不利。
在有关储能电池或动力电池等要求较高的市场应用， 要求隔膜兼具以下 特性：
1. 厚度均匀、 纳米级孔径、 平面方向具有合适、 均匀分布的孔隙率；
2. 在机械性能方面要求纵向具有高的拉伸强度、 横向具有高的韧性、 厚度方向耐挤压和局部针刺， 防止物理短路；
3.电池内部意外发热处于 130-200°C高温时，隔膜应具有熔融关断特性、 并且热收缩小； 耐高温破膜、 即使熔融仍具备机械完整性；
4. 厚度方向具备良好的压缩弹性，即在厚度方向受到压应力时隔膜具 备适当的弹性变形能力以适应负极膨胀的需要， 防止极片受不均匀压应力失 稳变形而皱曲； 受压变形的同时又不致于孔隙率降低很多甚至微孔闭合而影 响电池的正常放电； 压力释放后具备弹性回复能力， 保证正、 负极片与隔膜 间均匀紧密地接触、 不存在局部贫液。
为提高和弥补现有聚烯烃微孔隔膜的耐高温收缩及耐高温破膜性能， 中 国发明专利申请 200880003493. 7、 200880000072. 9报道了在聚烯烃微孔隔 膜表面采用粘接剂将氧化铝等陶瓷微粉连接成多孔涂层的复合隔膜技术方 案； 中国发明专利申请 200510086061. 5报道了在聚烯烃微孔隔膜表面采用 熔点 180°C以上耐高温的聚酰胺、 聚酰胺酰亚胺、 聚酰亚胺等形成多孔涂层 的技术方案； 中国发明专利申请 200480034190. 3提出在聚烯烃微孔隔膜表 面涂布可以凝胶化的氟树脂形成涂层的技术方案； 以上均是利用涂布方法在 聚烯烃微孔隔膜表面形成涂层， 主要不足之处在于：
1.由于现有聚烯烃隔膜基本属惰性材料， 与涂层之间粘接力不够、 涂层 厚了易剥离， 太薄抑制聚烯烃隔膜热收缩作用不明显；
2.由于聚烯烃隔膜的微孔存在毛细作用，在实施上述涂层方案时料浆中 的胶体及其料浆会进入聚烯烃隔膜的微孔中，在溶剂挥发干燥成膜后可 能影响隔膜的孔径分布和透气性， 涂层方法批量生产的一致性难以控 制， 另外涂层法复合隔膜制造成本高。
为提高隔膜与正极极片的粘接强度从而提高锂电池耐过充等方面的安 全性， 中国发明专利申请 01112218. 8提出在电解液中混合加入可以热交联 形成凝胶的单体聚合物， 利用该凝胶提高隔膜与正极极片的粘接强度， 同样 的该凝胶在热交联形成过程中会同样在隔膜的微孔中形成凝胶， 从而影响隔 膜的透过能力， 另外反应不完全的单体还可能会在正极侧氧化、 产气等， 甚 至会影响电池的循环性能。
为提高"湿法"隔膜的耐压缩性能，中国发明专利申请 200680010010. 7、 200680010890. 8、 200680010912. 0、 200680031471. 2报道了采用调整热拉伸 工艺的方案， 该方案在提高隔膜的压缩弹性性能方面仍然不够， 必须在 2. 2MPa/90 °C很高的压应力、 较高的温度下隔膜才有一定的膜厚变化率， 与 电池的实际应用需求仍有差距， 通常电池极片与隔膜之间的压应力不超过 50PSi (0. 35MPa) , 否则电池会鼓肚，另外若电池内压高于 0. 7MPa， 安全阔易 失效； 通常电池除注液前使用到 85-9CTC的高温干燥除水外， 正常使用温度 在 -1(T+60°C之间， 因此要求隔膜能适应在此温度范围内正常充放电条件下 的压缩弹性性能。
"湿法"聚烯烃复合隔膜方面采用共挤工艺制膜的报道还有， 中国发明 专利申请 200680035668. 3、 200780005795. 3 , 200510029794. 5等， 主要采 用调整层间聚烯烃原料的固含量、 采用聚乙烯 /聚丙烯的不同原料配比等以 及控制不同膜层原料的分子量等方法以得到层间不同的孔隙率和孔径分布、 膜层间不同的熔点的技术方案，这些共挤复合隔膜在提高隔膜的高温破膜温 度和耐压缩性能方面以及弹性性能方面仍显不足。
橡 /塑共混聚烯烃热塑性弹性体致密材料 (TP0， ΤΡΕ, TPV)采用动态硫化 经典的材料有 PP/EPDM、 PE /PSBR、 PE/EPDM等， 动态硫化工艺一般是在材 料的共混过程中采用交联剂将橡胶相动态交联， 边熔融剪切、 边动态交联， 冷却后的材料微观组织结构呈 "海 -岛"结构， 塑料相为连续相， 橡胶相为 岛状分布于塑料基体中，受制于熔体中橡胶相的高弹性和设备的混炼、剪切、 分散能力， 橡胶相的粒径处于微米级甚至百十微米的尺度， 几乎做不到亚微 米级或纳米级分布效果。
经过对锂离子电池安全性及使用寿命与电池隔膜材料之间关系， 为改善 现有单层、 多层聚烯烃微多孔隔膜的缺点，本发明人在中国发明专利申请
201110055620.1 中提出采用纳米预交联橡胶微粉改性的共挤复合隔膜以及 使用其的锂离子电池的技术路线， 其中的橡胶微粉原料是预交联好的物理和 化学状态， 其 1次微粒是纳米粒径， 但是存在纳米粉体特有的团聚问题， 团 聚后的 2次颗粒粒径在 5-50微米左右， 很难使之均匀弥散分布在聚烯烃微 孔隔膜基体中， 不易得到厚度精度高（±2微米）、微观组织、 力学性能分布 均匀的隔膜产品； 另外纳米橡胶微粉成本高。
经过对橡 /塑共混动态交联热塑性弹性体、 聚烯烃纳米级微多孔隔膜材 料加工工艺及微观组织结构之间关系的广泛深入地研宄， 本发明人在隔膜 的制造原料和工艺方法作全新的设计和调整，可以达成高弹性的橡胶材料均 匀弥散分布在聚烯烃纳米微孔基体中， 得到同时具备前述诸特性并能够使 锂离子电池在安全性能和循环性能均有所改善的聚烯烃微多孔隔膜，从而弥 补了现有技术的种种不足， 特提出以下发明内容。
发明内容
本发明的微多孔隔膜至少包括一层化学凝胶含量 20%以上的纳米微多孔 膜 A层，其微观结构设计为聚烯烃纳米微纤基体中均匀弥散经过后交联处理 的橡胶材料，形成橡、塑复合材料微多孔隔膜，橡胶、聚烯烃塑料原料的"橡 /塑比"设计为 (20 : 80)至 (60 : 40)， 微多孔隔膜可以是单层 A，更优选为复 合隔膜 A/B双层结构，另外一层纳米微多孔隔膜 B设计成聚烯烃塑料为主体， 其中的橡胶含量小于 20%; 微多孔隔膜同时具备以下特性：
1.总厚度在 8-40微米范围内， 优选 10-36微米， 平均孔径小于 150纳米， 孔隙率介于 35-70%， Gurley值介于 50-500S/100CC;
2.吸液溶胀及压缩弹性：在 30°C温度下，隔膜于自由状态下吸收 DMC液体 1 小时后厚度增大为吸液前的（1. 05-1. 30)倍，吸液后的隔膜在厚度方向施加 0. 35MPa静态压缩应力并保持 5分钟后， 隔膜在厚度方向的压缩变形量大 于压缩前厚度值的 5%、 小于 25%, 压力释放 5分钟后测试隔膜的厚度恢复 为压缩前的 85%以上；
3.隔膜的纵向拉伸强度介于 50_200MPa、 弹性模量大于 800MPa、 纵向断裂 伸长率大于 30%; 横向拉伸强度介于 30_150MPa、 弹性模量大于 300MPa、 横向断裂伸长率大于 50%, 针刺强度大于 300gf/20微米，
4.热关断及耐高温性能：在厚度方向施加 0. 35MPa 静态压缩应力， 从 90-200°C对隔膜以 l °C/min速率加热， 隔膜热关断温度不高于 145°C ;到 200°C并保持 5分钟后冷却至室温， 隔膜物理形态保持完整，其在纵向和 横向的热收缩率均小于 10%, Gurley值大于 2000S/100CC。
从锂离子动力电池隔膜的高强度、 热关断、 耐高温、 压缩弹性等综合特 性要求出发， 本发明的隔膜在厚度方向上优选设计成双层 A/B或三层 A/B/A 功能互补复合微多孔隔膜结构， 考虑到经济性， 更优选采用双层共挤工艺。 B层设计成聚烯烃塑料为主体、 其中的橡胶含量小于 20%, 其主要目的是为 复合隔膜提供高强度和高温热关断特性； 微多孔隔膜至少其中的一层 A设计 成高橡胶含量的纳米微多孔隔膜， 交联前的生胶原料特别选择低分子量的液 体橡胶或室温下呈蜡状固体的低结晶度橡胶，这样的生胶在 70-11CTC可以方 便地与高温相容剂混合搅拌成粘度介于二者之间的粘流体， 优选粘流体在 90-110°C下其动力粘度控制在 l-50Pa'S， 这样可以很方便地计量并喂入双螺 杆挤出机等混炼加工设备中； 聚烯烃塑料原料可以为粒料或粉末物理形态， 优选为粉料， 这样可以方便地和高温相容剂、 液体橡胶一起混合成均匀的料 浆再向挤出机喂料； 在 170-22CTC下与聚烯烃塑料基体混炼均匀成热力学溶 液， 经急冷铸片后、 再对片材进行热拉伸， 片材中聚烯烃塑料基体发生微纤 化、 网络化的物理形态转变， 其中分布的高温相容剂、 液体橡胶的组合物粘 流体与微纤复合在一起经历热拉伸塑形变形， 做到 "橡 /塑"微观上先均匀 分布， 之后再采用电子束辐照交联， 交联后橡胶具备的高弹性可以弥补聚烯 烃基体的弹性不足， 主要为隔膜提供压縮弹性和耐高温破膜性能、 并抑制高 温下聚烯烃固体甚至熔体的热收縮， 从而防止正、 负极片发生短路从而可以 提高锂离子电池的安全性和使用寿命。
橡胶原料采用重均分子量介于 30000-80000、 60 °C下的动力粘度 (Brookfield Viscosity, 7ft转子)在 50_1500Pa'S、 化学凝胶含量小于 10%、 与聚烯烃相容性良好的未硫化液体橡胶或室温下呈蜡状固体的低结晶度橡 胶 (60°C以上呈粘流态)，橡胶原料包括易辐照交联的乙丙橡胶 EPM、三元乙丙 橡胶 EPDM、 乙烯-丙烯酸酯橡胶、 或二烯烃类橡胶： 聚异戊二烯橡胶 IR、 顺 丁橡胶 BR、 弱极性的丙烯氰含量在 20%以下的丁腈橡胶 NBR、 苯乙烯含量在 20%以下的丁苯橡胶 SBR等或其组合物； 为便于辐照交联并且考虑到材料的 相容性，橡胶原料更优选与高密度聚乙烯基体溶解度参数相近的非极性乙丙 橡胶 EPM、 三元乙丙橡胶 EPDM, 优选主链中的乙烯 /丙烯的质量比介于 （50: 50 ) - ( 85： 15)， 其中适当高的乙烯占比有助于辐照交联， 由于甲基的位阻 效应高分子主链中的丙烯链段基本不会发生辐照交联， 乙烯占比过高时嵌段 聚合物易发生部分结晶， 部分结晶的好处是可以耐溶剂萃取， 缺点是降低了 橡胶的弹性； 对三元乙丙橡胶 EPDM原料而言， 第三单体包括亚乙基降冰片 烯 (ENB) , 1， 4-己二烯（HD)， 双环戊二烯 DCPD, 为便于辐照交联 EPDM中第 三单体的质量占比优选 3-12%。
聚烯烃塑料原料选用高密度聚乙烯 HDPE、 聚丙烯 PP、 聚丁烯 PB、 线性 低密度聚乙烯 LLDPE等乙烯、 丙烯、 丁烯的均聚物或与 α 烯烃的共聚物或 其组合物， 为使微多孔膜便于拉伸强化、 不易破膜、 关断温度控制在 130-145°C , 优选重均分子量 50万以上的易结晶的高密度聚乙烯， 更优选重 均分子量 150-300万的超高分子量聚乙烯，为改善聚乙烯与橡胶的相容性、 提高隔膜与电池极片的粘接力， 可以采用马来酸酐接枝改性后的聚乙烯 MAH-PE 与超高分子量聚乙烯 UHMWPE 的组合物一起作聚烯烃的原料，优选 MAH-PE在聚烯烃塑料原料中的重量百分比在 10%以上。
高温相容剂选用石蜡油或对苯二甲酸二辛酯 DT0P、 癸二酸二辛酯 D0S、 邻苯二甲酸二异壬酯 DINP、 邻苯二甲酸二异癸酯 DIDP等高沸点、 低分子量 (相对分子量 600 以下）、 低动力粘度 （0. 2Pa'S 以下） 的酯类增塑剂或其组 合物。
采用以上主要原料通过热致相分离法结合双向拉伸强化、 萃取、 辐照交 联等工艺有机组合来制造橡 /塑复合材料 "类互穿网络" 的纳米微孔隔膜， 主要工艺步骤及其设计思路继续解释如下： ( 1 )配料共混、 混炼、铸片， 首先在 70-110°C下把聚烯烃微米级粉体、 高温相容剂、 液体橡胶或蜡状橡胶、 抗氧剂等原料初步机械混合均匀成料浆 状，并溶胀 8-24 小时，稳定计量后输送进双螺杆挤出机等连续混炼设备，在 170-220°C的高温下把以上原料混炼加工成热力学均匀溶液， 将混炼均匀的 高温熔体经模头挤出后在金属辊表面连续快速凝固、相分离后得到物理凝胶 状态的 "冻胶半成品片材 A", 其中易结晶的聚烯烃作为三维骨架材料为 "冻 胶半成品片材 A"提供强度和足够的挺度， 便于后续的双向拉伸加工； 结晶 后的聚烯烃基本保持细小的片晶或球晶等物理状态， 而高温相容剂、 橡胶的 混合物的粘流体则高度精细地弥散分布于 "冻胶半成品片材 A" 中。
( 2 )双向热拉伸强化， 将 "冻胶半成品片材 A"预热到 105-13CTC后的 高塑性状态在厚度方向进行压延强化， 厚度压延比控制为 1-2. 5; 压延可以 强化厚度方向的强度， 防止隔膜受压时孔隙率下降太大而影响电池的内阻； 然后通过双向热拉伸强化工艺使聚烯烃由细小的片晶或球晶等物理状态发 生热塑性拉伸变形转变为微纤化、 网络化的物理形态， 而分布在聚烯烃片晶 或球晶之间的橡胶和高温相溶剂的组合物粘流体粘度较低， 能够跟随微纤发 生塑性变形、 流动、 填充、 从而均匀弥散分布在热拉伸后形成的聚烯烃微纤 三维网络骨架中，构成拉伸强化后的"复合材料薄膜半成品 B";热拉伸温度: 105-130°C , 热拉伸倍率 MD1介于 3-7， TD1介于 3_7； 双向拉伸可以是分步 拉伸或同步双向拉伸， 优选纵向拉伸稳定的同步拉伸工艺。
( 3 )低温萃取， 采用垸烃或卤代垸烃如癸垸、 R22、 R125、 四氯乙烯等 萃取溶剂在 0〜55°C温度条件下、在常压或 2-7MPa高压下，选择性萃取掉 "复 合材料薄膜半成品 B" 中的低分子量、 低粘度的高温相溶剂组分， 得到近无 高温相容剂的 "聚烯烃 /橡胶类互穿网络半成品微多孔膜 C2 "; "复合材料薄 膜半成品 B" 网络中分布的橡胶组分则可能由于以下机理不易被萃取出来而 基本 "原位"保留在聚烯烃微纤三维网络中： 橡胶组分的分子量相对高温相 容剂大得多、萃取工艺温度控制在 55 °C以下时橡胶高分子粘度较大、布朗运 动弱、 萃取时基本不存在剪切、 拉伸机械作用、 橡胶高分子不易解缠、 经历 了前面的 170-22CTC高温混炼、 热拉伸等热加工过程橡胶组分还可能发生部 分热交联。
萃取后溶剂挥发干燥时由于表面张力等作用， 微孔膜的孔径会变小、 厚 度、 宽度都会适当收缩， 优选对萃取后的 "聚烯烃 /橡胶类互穿网络半成品 微多孔膜 C2 "采用第 2次热拉伸和热定型工艺继续调节微多孔膜的孔径、孔 隙率、 厚度等指标， 得到 "聚烯烃 /橡胶类互穿网络近成品微多孔膜 D"。
( 4)在线电子束辐照交联， 对上述萃取之后的近无高温相容剂的 "聚 烯烃 /橡胶类互穿网络近成品微多孔膜 D "采用电子束在线辐照交联，辐照剂 量 50_250KGy， 辐照时优选采用氮气保护、 防止材料氧化黄变， 冷却收卷后 即得到先萃取后交联的橡胶、 聚烯烃复合材料纳米微多孔隔膜。 过低的辐照 剂量橡胶的交联度不足，过高的剂量易引起聚烯烃降解； 经过前述的第（1 )、 ( 2)、 ( 3 )加工步骤， 其中保持热塑性的橡胶组分在聚烯烃微纤网络中已经 分布均匀， 辐照的主要目的是使橡胶组分发生 "原位 "辐照交联、 形成高分 子体型网络， 提高弹性； 当聚烯烃优先选用高密度聚乙烯 HDPE时， 聚乙烯 微纤网络的缠结非晶区的高分子 PE也会发生部分辐照交联， 从而还可以提 高微孔隔膜在电池中使用时长时间受压条件下的抗蠕变性能和提高微孔隔 膜的弹性回复能力， 当然聚烯烃微纤和与其接触的液态橡胶之间还可能发生 部分接枝反应。
辐照交联工序也可以安排在前述的萃取工序（3)之前无孔的状态下进 行， 这样就不必担心辐照时多孔材料中存在的氧气的负面影响， 这种先辐照 后萃取的工艺基本流程如下： 对铸片后的 "冻胶半成品片材 A"采用如下工 艺步骤： 热压延、 双向热拉伸强化、 在线电子束辐照交联， 低温萃取、 第 2 次热拉伸、 热定型、 冷却收卷； 将 "冻胶半成品片材 A"预热后先在厚度方 向进行压延强化，厚度压延比控制为 1-2. 5; 然后通过双向热拉伸强化工艺， 热拉伸温度： 105-130°C， 热拉伸倍率 MD1介于 3-7， TD1介于 3_7； 双拉后 的膜即采用电子束在线辐照交联， 辐照剂量 50_250KGy; 低温萃取， 采用垸 烃或卤代垸烃等萃取溶剂在 (T55°C温度下、 在常压或 2-7MPa高压下， 选择 性萃取掉半成品膜中的高温相溶剂组分， 得到近无高温相容剂的 "聚烯烃 / 橡胶半成品微多孔膜 C1 ";对萃取后的半成品微多孔膜 C1采用第 2次热拉伸、 热定型继续调节微多孔膜的孔径、 孔隙率、 厚度等指标， 冷却收卷后即得到 后交联橡胶、 聚烯烃复合材料纳米微多孔隔膜。 这种先辐照后萃取的工艺安 排必须控制原材料的 "橡 /塑比"， 应以适当降低隔膜的压缩弹性为代价， 优选降低隔膜原料中的 "橡 /塑比"至 （40 : 60 ) 以下， 使交联后的橡胶与 聚烯烃微纤网络构成较弱的类 "互穿"结构、 或基本成 "岛 /海"非连续的 橡胶分布结构， 当橡胶相以均匀、 密集的小岛状镶嵌、 分布于聚烯烃微纤网 络基体中时， 还是可以跟随、 适应萃取后的第 2次热拉伸时聚烯烃微纤网络 基体的塑性变形、不致于第 2次热拉伸后的膜发生皱曲；而对高 "橡 /塑比"、 辐照交联后 "强互穿"状态的膜则不方便继续采用平面双向热拉伸工艺来调 节微孔膜的孔隙率、 孔径、 厚度等技术指标， 因为橡胶组分交联度提高后其 弹性上升、 塑性急剧下降， 网络状互联分布的橡胶会为膜在平面方向贡献一 定的高弹性， 易导致 2次热拉伸后隔膜发生皱曲。
采用共挤加工工艺制造复合隔膜， 与前述的各种涂层方法相比， 共挤复 合隔膜生产工艺简便， 生产成本低， 另外共挤加工时 A/B两层半成品中的聚 乙烯或聚烯烃高温熔体在界面具有一定的互缠结作用，可以保证两层间的高 粘接强度 /剥离强度， A/B层间 lOgf/cm以上的剥离强度可以利用具有高橡胶 含量的 A层更有效抑制高温下聚乙烯为主的 B层的热收缩。
共挤复合隔膜合适的孔径和孔隙率综合体现在透气性指标 Gurley值上， 过高的 Gurley值意味着隔膜微孔阻力大、 隔膜透过性差尤其是受压后透过 性更差， 电池容量不能有效发挥； 过低的初始 Gurley值意味着隔膜孔径偏 大或大孔多或孔隙率高、 电池容易自放电过快或易短路， 安全性不好， 因此 本发明优选共挤复合隔膜在室温下的 Gurley值为 50_500S/100CC， 优选隔 膜的平均孔径小于 200纳米，更优选隔膜的平均孔径小于 150纳米。
具体实施方式
以下， 关于本发明的具体实施方式 （以下简称 "实施方式"） 进行详细 说明。 而且本发明不限于下述实施方式的限定， 可以在要点范围内做各种 变形。
隔膜特性评价方法
( 1 ) 化学凝胶含量 将称量好的橡胶原料在二甲苯中于 100°C或成品隔膜于 135°C 煮沸 12小时以上，采用索氏抽提， 经隔膜过滤后称取残余物 W2与 初始的 W1比较，不溶物定义为凝胶，亦指化学凝胶含量。
(2 ) 膜厚 （ μ πι)
使用济南兰光机电技术有限公司生产的 CHY-C2型测厚仪进行 测定， 从多孔膜剪切 50mmX 50mm的样品， 用测厚仪在样品表面均 匀地进行 5点测量， 然后对膜厚的测定值进行平均。
( 3 ) 透气度
按照 JIS P8117的标准对微孔隔膜进行透气度测试。
(4) 针刺强度
测量仪器为 MTS公司的 CMT4000型电子测试机进行测试， 测 定用前端为球面 （曲率半径 R: 0. 5mm) 直径 1匪的针， 以 2mm/s 的速度扎入聚烯烃多孔膜时的最大负荷。
( 5 ) 拉伸强度、 弹性模量以及断裂伸长率
按照 GB/T 1040. 1-2006标准，使用宽为 25mm的长条状薄膜样 片， 采用 MTS公司的 CMT4000型电子测试机进行测定。
(6) 平均孔径
按照 IS015901. 1-2006标准， 采用压汞仪在 20-2000Psi压力 下测试隔膜的孔径分布和平均孔径。
( 7) 孔隙率
测试隔膜的假体密度 (g/cm3) =隔膜重量 / (厚度 *面积）， 与理论值. 94 g/cm3相除， 即视为微孔隔膜的孔隙率。 (8 ) 隔膜的吸液溶胀和压縮弹性测试
在 30°C下在碳酸二甲酯 DMC中先浸泡吸液 1小时， 测试吸液 前后的厚度； 然后用 0. 35MPa的压应力对隔膜在厚度方向压制并 保持 5分钟， 用薄膜厚度测试仪测量压制前、 后的厚度。
( 9) 热关断温度、 热收縮及耐高温破膜测试
将隔膜压在玻璃平板中间，在厚度方向施加 0. 35MPa静态压缩应力， 从 90-145°C对隔膜以 l °C/min速率加热， 到 145°C并保持 5分钟后冷却 至室温后测试 Gurley 值， 大于 2000S/100CC 即视为热关断温度小于 145°C ; 从 90到 200°C对隔膜以 l °C/min速率加热， 到 200°C并保持 5分 钟后冷却至室温，测试 Gurley值及观察冷却后的隔膜物理形态保持完整， 测试热缩后隔膜在纵向和横向的长度， 热收缩率= (初始长度 -缩后长度) /初始长度 *100%。
实施例 1 :
后交联橡胶、 聚烯烃复合材料纳米微孔隔膜及其制造方法
共挤复合隔膜材料配方：
A层配方：重均分子量（Mw) 250万的超高分子量聚乙烯 (UHMWPE) IO份； 重均分子量 35万的马来酸酐接枝高密度聚乙烯 15份； 重均分子量 42000、 60°C下 Brookfield粘度 800Pa*S、 乙烯 /丙烯质量比 75/25、 第三弹体 ENB 含量 10. 5%的液体三元乙丙橡胶 EPDM (Trilene 77) 10份， 癸二酸二辛酯 (DOS): 65份； 抗氧剂 1010: 0. 3份;
B层配方：重均分子量（Mw) 250万的超高分子量聚乙烯 (UHMWPE) IO份； 重均分子量 35万的马来酸酐接枝高密度聚乙烯 15份； 60°C下 Brookfield 粘度 800Pa*S、 乙烯 /丙烯质量比 75/25、 第三弹体 ENB含量 10. 5%的液体三 元乙丙橡胶 (Tri lene 77) 5份， 癸二酸二辛酯 ( DOS) : 70份; 抗氧剂 1010: 0. 3份。
共挤复合隔膜加工方法：
( 1 ) 配料、共挤铸片：将上述 A， B 两种原料分别在两个真空搅拌釜 中于 95°C溶胀混合处理 16小时， 配制成均匀料浆； 然后通过计量泵分 别将料浆按同等喂料量输入长径比 1 : 60的平行同向双螺杆挤出机 A和 B中进行熔融混炼，挤出机的温度设置范围为： 185°C-210°C之间； A和 B 层的熔体经过混流器后进入同一个共挤平模头挤出并急冷铸片，冷却速 度控制大于 200°C/30S， 铸片厚度控制为 1. 6mm;
( 2 ) 热压延、 同步双向热拉伸、 在线辐照交联： 将上述铸片的复合 片材经 115-125°C预热后热压延， 压延比 1. 3，然后进入同步拉伸， 纵向 拉伸倍率 4倍，横向拉伸倍率为 3倍，从同步烘箱出来后的膜采用 500KV 的自屏蔽电子帘加速器在线辐照交联，辐照剂量 150KGy; 材料冷却到 30°C以下后与 PP无纺布复合后收卷， 卷径 900mm;
( 3 ) 气液两相高压萃取： 将复合成卷的产品放入萃取釜中进行清 洗， 清洗工艺为： 清洗温度: 55 °C， 清洗压力: 6. 0MPa， 分离压力为 1. 5-1. 8MPa，分离温度为 65°C，萃取溶剂在整个系统中循环对产品清洗；
(4) 分步热拉伸， 对上述萃取后的半成品膜经 115-125°C预热后先 纵向热拉伸 1. 5倍， 横向热拉伸 1. 3倍， 热拉伸温度 125°C ;
( 5 ) 热定型处理， 横拉后的膜在 115-128°C在宽度方向保持 20-40 秒； (6) 冷却收卷，将上述经过热定型的膜冷却至 30°C以后收卷即得成 品共挤复合微多孔膜；
共挤复合隔膜具备以下特性：
产品厚度 25 微米； 平均孔径 95 纳米； 孔隙率 48%; Gurley 值： 200-260S/100CC; 拉伸强度： MD方向 128MPa， TD方向 85MPa; 断裂伸长 率：纵向 55%，横向 113%;弹性模量： MD方向 1492MPa, TD方向 831MPa; 针刺强度 390gf; 化学凝胶含量： 30%;
在 30°C温度下， 将共挤复合隔膜在厚度方向施加 0.35MPa静态压缩应 力并保持 5分钟后， 共挤复合隔膜的厚度为 23微米， 压力释放 5分钟后测 试共挤复合隔膜的厚度为 24微米,如此压缩 /释放循环 2000次后隔膜仍保持 压缩弹性、 压力释放 5分钟后测试共挤复合隔膜的厚度为 22微米。
在 30°C温度下，将共挤复合隔膜在碳酸二甲酯 DMC中先浸泡吸液 1小 时， 测试吸液后的厚度为 30微米； 对吸液后的共挤复合隔膜在厚度方向施 加 0.35MPa静态压缩应力并保持 5分钟后，共挤复合隔膜的厚度为 28微米， 压力释放 5分钟后测试共挤复合隔膜的厚度为 29微米,如此吸液状态下的压 缩 /释放循环 2000次后隔膜仍保持压缩弹性、 压力释放 5分钟后测试共挤复 合隔膜的厚度为 25微米。
在 145°C对共挤复合隔膜在厚度方向施加 0. 35MPa静态压缩应力并保持 60分钟后冷却至室温， 隔膜保持形态完整，其在纵向和横向的热收缩率均小 于 8%； Gurley值大于 2000S/100CC。
在厚度方向施加 0. 35MPa静态压缩应力，从 90-200°C对共挤复合隔膜以 rC/min速率加热， 到 200°C并保持 5分钟后冷却至室温， 隔膜仍保持完整， 其在纵向和横向的热收缩率均小于 6%， Gurley值大于 2600S/100CC。
采用该复合隔膜， 其 A侧与电池的负极极片接触， B侧与电池的正 极极片接触， 在注液前将极组在 95°C/lMPa下加压 15min，经干燥后注 入电解液做成锂离子电池， 测试 150°C热箱、 针刺、 短路、 室温 25°C下 的 1C循环， 电池安全性试验全部合格， 循环寿命： 2350次。
对比例 1
电池制作同实施例 1， 仅隔膜采用某公司的干法 PP/PE/PP膜， 厚 度 25微米， 孔隙率 40%, Gurley值 600- 630S/100CC, 拉伸强度： MD 方向 165MPa， TD方向 13MPa， 横向断裂伸长率 12%。 在 30°C温度下， 将该隔膜在厚度方向施加 0.35MPa静态压缩应力并保持 5分钟后，共挤复合 隔膜的厚度为 23.5微米， 压力释放 5分钟后测试隔膜的厚度仍然为 23.5微 米， 缺乏弹性回复能力;如此压缩 /释放循环 50次后隔膜的厚度为 23微米， 停止试验。
电池循环寿命： 635 次， 安全性试验短路合格、 150°C热箱、 针刺 不合格。
对比例 2
电池制作同实施例 1， 仅隔膜采用某公司的湿法单层 PE隔膜， 厚 度 25微米，孔隙率 49%， Gurley值 95S/100CC,拉伸强度： MD方向 143MPa， TD方向 21MPa， 纵向断裂伸长率 42%， 横向断裂伸长率 344%。
在 30°C温度下， 将该隔膜在厚度方向施加 0.35MPa静态压缩应力并保 持 5分钟后， 共挤复合隔膜的厚度为 23微米， 压力释放 5分钟后测试隔膜 的厚度仍然为 23微米， 缺乏弹性回复能力;如此压缩 /释放循环 50次后隔膜 -
的厚度为 22微米， 停止试验

Claims

权 利 要 求 书
1、 后交联橡胶、 聚烯烃复合材料纳米微多孔隔膜，其特征在于， 复合材料纳 米微多孔隔膜至少包括一层化学凝胶含量 20%以上的纳米微多孔膜 A层， 其微 观结构为聚烯烃纳米微纤基体中均匀弥散经过后交联处理的橡胶材料， 形成 橡、塑复合材料纳米微多孔隔膜； 橡胶、聚烯烃塑料原料的"橡 /塑比"为 (20 : 80)至 (50: 50)； 复合材料纳米微多孔隔膜可以是单层 A，更优选为双层复合隔 膜 A/B, 另外一层纳米微多孔隔膜 B采用聚烯烃塑料为主体， 所采用的橡胶、 聚烯烃塑料原料中橡胶含量小于 20%;
复合材料纳米微多孔隔膜的橡胶原料采用重均分子量介于 30000-80000、 60°C下的动力粘度在 50-1500Pa'S、 化学凝胶含量小于 10%、 与 聚烯烃相容良好的未硫化液体橡胶或室温下呈蜡状固体的低结晶度橡胶，橡胶 原料包括易辐照交联的乙丙橡胶 EPM、 三元乙丙橡胶 EPDM、 乙烯 -丙烯酸酯橡 胶、 或二烯烃类橡胶： 聚异戊二烯橡胶 IR、 顺丁橡胶 BR、 丙烯氰含量在 20% 以下的丁腈橡胶 NBR、 苯乙烯含量在 20%以下的丁苯橡胶 SBR等或其组合物； 复合材料纳米微多孔隔膜的聚烯烃塑料原料选用高密度聚乙烯 HDPE、 聚 丙烯 PP、 聚丁烯 PB、 线性低密度聚乙烯 LLDPE等乙烯、 丙烯、 丁烯的均聚物 或与 α烯烃的共聚物或其组合物，优选重均分子量 50万以上的高密度聚乙烯； 复合材料纳米微多孔隔膜制造中采用的高温相容剂选用石蜡油、对苯二甲 酸二辛酯 DT0P、 癸二酸二辛酯 D0S、 邻苯二甲酸二异壬酯 DINP、 邻苯二甲酸 二异癸酯 DIDP等高沸点、 低分子量、 低动力粘度的酯类增塑剂或其组合物； 复合材料纳米微多孔隔膜同时具备以下特性：
( 1 )总厚度在 10-36微米范围内，平均孔径小于 150纳米，孔隙率介于 35-70%, Gurley值介于 50-500S/100CC; ( 2 ) 吸液溶胀及压缩弹性：在 30°C温度下， 隔膜于自由状态下吸收 DMC液体 1 小时后厚度增大为吸液前的（1. 05-1. 30)倍， 吸液后的隔膜在厚度方向施加 0. 35MPa静态压缩应力并保持 5分钟后， 隔膜在厚度方向的压缩变形量大于压 缩前厚度值的 5%、 小于 25%, 压力释放 5分钟后测试隔膜的厚度恢复为压缩前 的 85%以上；
( 3 ) 隔膜的纵向拉伸强度介于 50_200MPa、 弹性模量大于 800MPa、 纵向断裂 伸长率大于 30%; 横向拉伸强度介于 30_150MPa、 弹性模量大于 300MPa、 横向 断裂伸长率大于 50%, 针刺强度大于 300gf/20微米；
( 4 ) 热关断及耐高温性能：在厚度方向施加 0. 35MPa 静态压缩应力， 从 90-200°C对隔膜以 rC/min速率加热，隔膜热关断温度不高于 145°C ;到 200°C 并保持 5分钟后冷却至室温， 隔膜物理形态保持完整，其在纵向和横向的热收 缩率均小于 10%, Gurley值大于 2000S/100CC。
2、 根据权利要求 1所述的复合材料纳米微多孔隔膜， 其特征在于， 其中 A、 B 层微多孔膜中的聚烯烃原料中含有重量百分比 10%以上的马来酸酐接枝聚乙 烯 MAH- PE。
3、一种后交联橡胶、聚烯烃复合材料纳米微多孔隔膜的制造方法，其特征在于， 至少包括如下加工工艺： A、 配料共混、 混炼、 铸片； B、 双向热拉伸强化； C、 在线电子束辐照交联； D、 低温萃取、 第 2次热拉伸和热定型。
4、 根据权利要求 3所述的后交联橡胶、 聚烯烃复合材料纳米微多孔隔膜的制 造方法，其特征在于， 配料共混采用如下工艺： 首先在 70-11CTC下把聚烯烃、 高温相容剂、液体橡胶或蜡状橡胶、抗氧剂等原料初步机械混合均匀成料浆状， 并溶胀 8-24小时，然后稳定计量后输送进双螺杆挤出机等设备进行连续混炼、 铸片得到 "冻胶半成品片材 A"。
5、根据权利要求 3、 4所述的后交联橡胶、 聚烯烃复合材料纳米微多孔隔膜的 制造方法，其特征在于，对铸片后的 "冻胶半成品片材 A"采用如下工艺步骤： 热压延、 双向热拉伸强化、 在线电子束辐照交联， 低温萃取、 第 2次热拉伸、 热定型、 冷却收卷； 将 "冻胶半成品片材 A"预热后先在厚度方向进行压延强 化， 厚度压延比控制为 1-2. 5 ; 然后通过双向热拉伸强化工艺，热拉伸温度： 105-130°C , 热拉伸倍率 MD1介于 3-7， TD1介于 3_7； 双拉后的膜即采用电子 束在线辐照交联， 辐照剂量 50_250KGy; 低温萃取， 采用垸烃或卤代垸烃等萃 取溶剂在 0〜55°C温度下、 在常压或 2-7MPa高压下， 选择性萃取掉半成品膜中 的高温相溶剂组分， 得到近无高温相容剂的 "聚烯烃 /橡胶半成品微多孔膜 C1 "; 对萃取后的半成品微多孔膜 C1采用第 2次热拉伸、热定型继续调节微多 孔膜的孔径、 孔隙率、 厚度等指标， 冷却收卷后即得到后交联橡胶、 聚烯烃复 合材料纳米微多孔隔膜。
6、根据权利要求 3、 4所述的后交联橡胶、 聚烯烃复合材料纳米微多孔隔膜的 制造方法，其特征在于，对铸片后的半成品采用如下工艺步骤： 热压延、双向热 拉伸强化、 低温萃取、 第 2次热拉伸、 热定型、 在线电子束辐照交联、 冷却收 卷； 将 "冻胶半成品片材 A"预热后先在厚度方向进行压延强化， 厚度压延比 控制为 1-2. 5; 然后通过双向热拉伸强化工艺，热拉伸温度： 105-130°C， 热拉 伸倍率 MD1介于 3-7， TD1介于 3-7; 低温萃取， 采用垸烃或卤代垸烃等萃取 溶剂在 0〜55°C温度下、 在常压或 2-7MPa高压下， 选择性萃取掉半成品膜中的 高温相溶剂组分， 得到近无高温相容剂的 "聚烯烃 /橡胶类互穿网络半成品微 多孔膜 C2 "; 对萃取后的 "聚烯烃 /橡胶类互穿网络半成品微多孔膜 C2 "采用 第 2次热拉伸和热定型工艺继续调节微多孔膜的孔径、 孔隙率、 厚度等指标， 得到 "聚烯烃 /橡胶类互穿网络近成品微多孔膜 D ", 之后采用在线电子束辐照 交联， 辐照剂量 50_250KGy; 冷却收卷得到后交联橡胶、 聚烯烃复合材料纳米 微多孔隔膜。
7、 一种含有后交联橡胶、 聚烯烃复合材料纳米微多孔隔膜的锂离子电池， 其 特征在于， 含有正极极片、 负极极片、 电解液以及采用权利要求 1-6所述的后 交联橡胶、 聚烯烃复合材料纳米微多孔隔膜。
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