WO2017063218A1 - 一种锂离子电池复合隔膜及其制备方法以及一种锂离子电池 - Google Patents

一种锂离子电池复合隔膜及其制备方法以及一种锂离子电池 Download PDF

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WO2017063218A1
WO2017063218A1 PCT/CN2015/092663 CN2015092663W WO2017063218A1 WO 2017063218 A1 WO2017063218 A1 WO 2017063218A1 CN 2015092663 W CN2015092663 W CN 2015092663W WO 2017063218 A1 WO2017063218 A1 WO 2017063218A1
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separator
lithium ion
ion battery
battery
coating
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PCT/CN2015/092663
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English (en)
French (fr)
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肖亚洲
怀永建
赵金保
白莉
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中航锂电（洛阳）有限公司
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Publication of WO2017063218A1 publication Critical patent/WO2017063218A1/zh

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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
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M50/409—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
    • H01M50/443—Particulate material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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 belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery composite diaphragm, a preparation method thereof and a lithium ion battery.
  • Battery separator refers to a thin porous material between the positive and negative electrodes of the battery. It is a very critical part of the battery and has a direct impact on the safety and cost of the battery. It has high ion permeability and good mechanical strength and long-term stability to chemicals and solvents used in electrolytes such as batteries.
  • Typical organic membranes are polyolefin microporous membranes such as polyethylene microporous membranes or polypropylene microporous membranes. Due to the chemical composition and molding process of polyolefin itself, its physical and chemical properties are determined, which has caused some defects in the application of lithium ion power battery separator.
  • polyolefin microporous membranes used in battery separators are: (1) polyolefins as non-polar materials have poor affinity with strongly polar electrolytes, resulting in poor liquid retention; (2) The olefin microporous membrane is usually obtained by mechanical stretching and pore-forming, or organic solvent extraction after mechanical stretching, and then obtained by heat setting. Eventually the film has a shape memory effect, and at higher temperatures, the membrane tends to restore the shape of the film before stretching, resulting in greater heat shrinkage. Although the melting temperature of the polyolefin is low, the substrate is liable to melt at temperatures above 165 ° C, causing the micropores to disappear, blocking ion conduction, a so-called fuse protection effect.
  • microporous polyolefin film when the microporous polyolefin film is melted, it is accompanied by volume shrinkage, and the membrane area is reduced, so that the diaphragm loses the barrier function between the positive and negative electrodes, thereby causing a short circuit between the positive and negative electrodes inside the battery, causing the battery to burn or even explode. Security risks.
  • the way to improve the thermal stability of the separator in the industry is mainly by applying the physical properties of the high temperature resistant material, coating the surface of the polyolefin with high temperature resistant inorganic materials such as aluminum oxide and high temperature resistant organic materials such as aramid, etc.
  • a high temperature resistant separator substrate such as a polyimide separator.
  • it does not prevent further increase in battery temperature, and it is impossible to effectively ensure the safety of the battery.
  • the technical problem to be solved by the present invention is to provide a lithium ion battery composite diaphragm, a preparation method thereof, and a lithium ion battery.
  • the lithium ion battery composite diaphragm provided by the invention can suppress the battery temperature rise and protect the battery. Security.
  • the invention provides a composite membrane of a lithium ion battery, comprising a membrane substrate and a functional coating compounded on the surface of the membrane substrate, the functional coating being prepared by a functional substance and a binder, the function
  • the substance is selected from one or more of a phosphorus-containing compound, a nitrogen-containing compound, and an inorganic silicon-based compound.
  • the functional substance is selected from the group consisting of pentaerythritol melamine phosphate and salts thereof, ammonium polyphosphate, polyphosphoramide compounds, organic phosphazene polymers, polysiloxane compounds, and thiourea compounds. Or a variety.
  • the functional substance is one or more selected from the group consisting of melamine cyanurate, pentaerythritol melamine phosphate, ammonium polyphosphate, polydimethylsiloxane, and melamine pyrophosphate.
  • the mass ratio of the functional substance to the binder is (90 to 99): (1 to 10).
  • the functional coating has a single side thickness of 3 to 6 ⁇ m.
  • the membrane substrate is selected from a polyolefin microporous membrane or a polyolefin-based ceramic membrane.
  • the binder is one or more of polyvinylidene fluoride and copolymers thereof, acrylic acid and copolymers thereof, acrylates and copolymers thereof, polyvinyl alcohol, carboxymethyl fibers and polyurethane.
  • the invention also provides a preparation method of a composite membrane for a lithium ion battery, comprising the following steps:
  • the sexual substance is selected from one or more of a phosphorus-containing compound, a nitrogen-containing compound, and an inorganic silicon compound;
  • the coating is selected from the group consisting of transfer coating, dip coating, knife coating, gravure coating, spray coating or screen printing.
  • the present invention also provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, the separator being the lithium ion battery composite separator described above.
  • the present invention provides a composite membrane of a lithium ion battery, comprising a membrane substrate and a functional coating compounded on the surface of the membrane substrate, the functional coating being composed of a functional substance and a binder Prepared, the functional substance is selected from one or more of a phosphorus-containing compound, a nitrogen-containing compound, and an inorganic silicon compound.
  • the lithium ion battery composite separator provided by the invention is coated with a functional coating on the surface of the diaphragm substrate, and the functional coating can quickly absorb excess heat of the battery when the temperature of the lithium ion battery increases, as a reaction entropy, spontaneously
  • a protective layer is formed on the surface of the diaphragm, which can effectively suppress the continuous increase of the temperature of the battery, reduce the heat shrinkage of the diaphragm, and on the other hand, passivate the active layer of the anode and cathode of the battery, and control the battery from the root source. Safety hazards to ensure the safety of the battery.
  • the functional coating of the present invention has a small hardness, the process loss in the battery manufacturing process can be reduced, thereby reducing the production cost of the battery.
  • the lithium ion battery composite separator provided by the invention exhibits less heat shrinkage at different temperatures and has good thermal stability; the lithium ion battery composite membrane has a liquid absorption amount of 61 in 30 minutes. ⁇ 89 g/m 2 ;
  • the composite separator was prepared as a lithium ion battery, which had a capacity retention rate of >90% in 1500 cycles, and had superior safety performance when subjected to battery safety testing.
  • the invention provides a composite membrane of a lithium ion battery, comprising a membrane substrate and a functional coating compounded on the surface of the membrane substrate, the functional coating being prepared by a functional substance and a binder, the function
  • the substance is selected from one or more of a phosphorus-containing compound, a nitrogen-containing compound, and an inorganic silicon-based compound.
  • the lithium ion battery separator provided by the present invention includes a separator substrate.
  • the present invention is not particularly limited to the separator substrate of the lithium ion battery, and a separator substrate which can be used for a lithium ion battery, which is well known to those skilled in the art, may be used.
  • the separator substrate is preferably a polyolefin microporous film or a polyolefin-based ceramic film.
  • the polyolefin microporous membrane of the present invention may be a polypropylene microporous membrane, a polyethylene microporous membrane, or a composite membrane of different kinds of polyolefin microporous membranes.
  • the ceramic material in the polyolefin-based ceramic film of the present invention is preferably alumina or boehmite.
  • the membrane substrate is a polypropylene microporous membrane; in other embodiments of the invention, the membrane matrix is a polyethylene microporous membrane.
  • the separator substrate is a polyethylene-based ceramic separator; in other embodiments of the invention, the separator substrate is a polypropylene-based ceramic separator.
  • the thickness of the separator substrate is preferably 10 to 60 ⁇ m, preferably 10 to 55 ⁇ m, more preferably 15 to 50 ⁇ m, and most preferably 12 to 25 ⁇ m.
  • the lithium ion battery separator provided by the present invention further comprises a functional coating compounded on the surface of the separator substrate, the functional coating being prepared from a functional substance and a binder.
  • the functional coating provided by the invention comprises a functional substance, and the functional substance for preparing the functional coating of the surface of the separator of the lithium ion battery can absorb the heat of the battery as the reaction entropy, spontaneously In response to the chemical reaction, a protective layer is formed on the surface of the separator.
  • the functional substance is one or more selected from the group consisting of a phosphorus-containing compound, a nitrogen-containing compound, and an inorganic silicon-based compound.
  • the functional substance is selected from the group consisting of pentaerythritol melamine phosphate and salts thereof, ammonium polyphosphate, polyphosphoramide compounds, organic phosphazene polymers, polysiloxane compounds, and thiourea compounds. Or a variety.
  • the functional substance is selected from the group consisting of melamine cyanurate and its derivatives, pentaerythritol melamine phosphate and its derivatives, ammonium polyphosphate and its derivatives, polydimethylsiloxane and its derivatives. And one or more of melamine pyrophosphate and its derivatives.
  • the functional substance is selected from one or more of the group consisting of melamine cyanurate, pentaerythritol melamine phosphate, ammonium polyphosphate, polydimethylsiloxane, and melamine pyrophosphate.
  • the functional substance is selected from the group consisting of melamine cyanurate (MCA); in other embodiments of the invention, the functional substance is selected from the group consisting of pentaerythritol melamine phosphate (PPMS) In another embodiment of the present invention, the functional substance is selected from the group consisting of a trimeric nitrile pyrophosphate (MPP); in other embodiments of the invention, the functional substance is selected from the group consisting of melamine Phosphate (MPOP); In other embodiments of the invention, the functional substance is selected from the group consisting of ammonium polyphosphate (APP); in other embodiments of the invention, the functional substance is selected from the group consisting of a mixture of a trimeric nitrile pyrophosphate (MPP) and a melamine cyanurate (MCA); in other embodiments of the invention, the functional substance is selected from the group consisting of polydimethylsiloxane (PDMS) The coated polyammonium
  • the polydimethylsilane and ammonium polyphosphate were rapidly stirred on a high speed disperser at a line speed of 10 to 80 m/s for 15 to 60 minutes to obtain polydimethylsiloxane-coated ammonium polyphosphate particles (PDMS-APP). ).
  • the functional coating provided by the present invention further comprises a binder selected from the group consisting of polyvinylidene fluoride and copolymers thereof, acrylic acid and copolymers thereof, acrylates and copolymers thereof, polyvinyl alcohol, carboxymethyl groups.
  • a binder selected from the group consisting of polyvinylidene fluoride and copolymers thereof, acrylic acid and copolymers thereof, acrylates and copolymers thereof, polyvinyl alcohol, carboxymethyl groups.
  • One or more of the fibers and polyurethane are preferably one or more of a polyvinylidene fluoride film (PVDF), a styrene butadiene rubber (SBR), and an LA132 aqueous binder.
  • PVDF polyvinylidene fluoride film
  • SBR styrene butadiene rubber
  • LA132 aqueous binder an LA132 aqueous binder.
  • the mass ratio of the functional substance to the binder is (80 to 99): (1 to 20), preferably (90 to 99): (1 to 10).
  • the mass ratio of the functional substance to the binder is 96:4; in other embodiments of the invention, the quality of the functional substance and the binder Ratio is 97:3; in other specific implementations of the invention
  • the mass ratio of the functional substance to the binder is 98:2.
  • the mass ratio of the functional substance to the binder is 95:5.
  • the mass ratio of the functional substance to the binder is 95.5:4.5.
  • the functional coating may be composited on one side of the separator substrate or may be composited on both sides of the separator substrate.
  • the functional coating according to the invention has a single-sided thickness of from 2 to 15 ⁇ m, preferably from 3 to 6 ⁇ m. In some embodiments of the invention, the thickness of the coating is 3 ⁇ m; in other embodiments of the invention, the thickness of the coating is 4 ⁇ m; in other embodiments of the invention, The thickness of the coating was 5 ⁇ m.
  • the lithium ion battery composite separator has a thickness of 12 to 75 ⁇ m, preferably 15 to 70 ⁇ m, and more preferably 15 to 37 ⁇ m.
  • the invention also provides a preparation method of the above lithium ion battery composite separator, comprising the following steps:
  • the present invention firstly disperses a functional substance and a binder in a solvent to obtain a mixed slurry.
  • the method of the present invention is not particularly limited, and a dispersion method known to those skilled in the art may be used. In the present invention, dispersion is preferably carried out as follows:
  • a functional substance and a binder are separately dispersed in a solvent, and then mixed to obtain a mixed slurry.
  • the linear velocity of the high-speed disperser is preferably from 10 to 80 m/s, and the dispersion time is preferably from 10 min to 90 min.
  • the solvent includes, but is not limited to, one or more of deionized water, ethanol, benzene, toluene, NMP, and acetone. In some embodiments of the invention, the solvent is preferably deionized water or NMP.
  • the solid content in the mixed slurry is adjusted by using a solvent, and finally the solid content in the mixed slurry is controlled to be 30 wt% to 60 wt%, preferably 35 wt% to 50 wt%, and the adjusted mixed pulp used in the present invention.
  • the solvent in the solid content of the material includes but is not limited to One or more of deionized water, ethanol, benzene, toluene, NMP and acetone.
  • the mixed slurry is applied to the surface of the separator substrate and dried to obtain a lithium ion battery composite separator.
  • the method for applying the mixed slurry to the surface of the separator substrate of the present invention is not particularly limited, and a coating method known to those skilled in the art may be used.
  • a coating method known to those skilled in the art may be used.
  • transfer coating, dip coating, knife coating, gravure coating, spray coating or screen printing is preferably employed.
  • the drying method of the present invention is not particularly limited, and a drying method known to those skilled in the art may be used.
  • the drying temperature is preferably 40 to 90 °C.
  • the present invention also provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, the separator being selected from the above-described lithium ion battery composite separator.
  • the type of the positive electrode, the negative electrode, and the electrolytic solution of the present invention is not particularly limited, and the types of the positive electrode, the negative electrode, and the electrolytic solution of the lithium ion battery known to those skilled in the art may be used.
  • the negative active material includes, but is not limited to, one or more of graphite, hard carbon, lithium titanate, and soft carbon.
  • the lithium ion battery composite separator provided by the invention can increase the thermal stability of the separator and reduce the heat shrinkage of the diaphragm by virtue of the physical properties of the functional coating against high temperature.
  • the safety of the battery is initially ensured, so that the battery does not quickly cause an internal short circuit and other safety hazards.
  • the lithium ion battery composite separator provided by the invention has excellent chemical properties of the functional coating, and after the battery temperature rises, the functional coating can quickly absorb excess heat of the battery, acts as a reaction entropy, spontaneously responds to the chemical reaction, and generates protection. Floor. On the one hand, it effectively suppresses the continuous increase of the temperature of the battery, and on the other hand, the active layer of the anode and cathode of the passivation battery controls the safety hazard of the battery from the root source to ensure the safety of the battery.
  • the functional coating of the present invention has a small hardness, the process loss in the battery manufacturing process can be reduced, thereby reducing the production cost of the battery.
  • the lithium ion battery composite separator provided by the invention exhibits less heat shrinkage at different temperatures and has good thermal stability; the lithium ion battery composite membrane has a liquid absorption amount of 61 in 30 minutes. ⁇ 89 g/m 2 ;
  • the composite separator was prepared as a lithium ion battery, which had a capacity retention rate of >90% in 1500 cycles, and had superior safety performance when subjected to battery safety testing.
  • the lithium ion battery composite separator provided by the present invention a preparation method thereof, and a lithium ion battery will be described below with reference to the embodiments, and the scope of the present invention is not limited by the following examples.
  • MCA melamine cyanurate
  • PVDF polyvinylidene fluoride film
  • the mixed slurry was coated on the polypropylene side of a 25 ⁇ m biaxially oriented polypropylene separator ceramic separator, and dried at 80 ° C to obtain a coating thickness of 4 ⁇ m to obtain a functional coating/biaxially oriented polypropylene film/ Composite diaphragm of ceramic layer.
  • the ceramic layer is nano-alumina having a purity of 99.999%.
  • Positive electrode Active material LiNi 1/3 Co 1/3 Mn 1/3 O 2 , 4 wt% of conductive agent carbon black and 3 wt% of binder PVDF were added to the solvent NMP in an amount of 93 wt%, respectively.
  • the ternary positive electrode slurry is uniformly prepared, and the positive electrode slurry is uniformly coated on a positive current collector Al foil having a thickness of 20 ⁇ m, dried to obtain a positive electrode, and rolled to stand;
  • a negative electrode active material graphite powder having a mass fraction of 95% by weight, 2% by weight of a conductive agent carbon black, 1% by weight of a thickener CMC (carboxymethylcellulose sodium) and 2wt were added to the solvent deionized water.
  • % binder SBR styrene-butadiene rubber
  • the negative electrode slurry was uniformly coated on a negative current collector Cu foil having a thickness of 10 ⁇ m, dried to obtain a negative electrode, and rolled to stand;
  • An electrolyte solution was injected into a lithium ion battery module to obtain a lithium ion secondary battery.
  • the electrolyte was LiPF 6 in a system consisting of EC, EMC and DMC, the concentration of LiPF 6 was 1 mol/L, and the volume ratio of EC, EMC and DMC was 1:1:1.
  • Pentaerythritol melamine phosphate (PPMS) and polyvinylidene fluoride film (PVDF) were accurately weighed according to a mass ratio of 98:2.
  • PPMS and PVDF were uniformly dispersed in solvent NMP on a high-speed disperser to obtain PPMS slurry and PVDF slurry, and the above two kinds of slurry were uniformly dispersed, and the solid content in the slurry was adjusted to 39 wt% by solvent NMP. Mix the slurry.
  • the mixed slurry was coated on the polyethylene side of a 25 ⁇ m polyethylene ceramic separator, dried at 65 ° C, and the coating thickness was controlled to be 3 ⁇ m to obtain a composite coating of a functional coating/polyethylene film/ceramic layer.
  • the ceramic layer is nano-alumina having a purity of 99.999%.
  • the process of battery fabrication was the same as in Example 1, except that the composite separator of Example 1 was replaced with the composite separator prepared in the present example.
  • APP polyphosphate
  • PDMS polydimethylsiloxane
  • SBR styrene butadiene rubber
  • the mixed slurry was coated on the polypropylene side of a 20 ⁇ m biaxially oriented polypropylene-based ceramic separator, and dried at 70 ° C to obtain a coated thickness of 5 ⁇ m to obtain a functional coating/biaxially oriented polypropylene film/ Composite diaphragm of ceramic layer.
  • the ceramic layer is nano-alumina having a purity of 99.999%.
  • the process of battery fabrication was the same as in Example 1, except that the composite separator of Example 1 was replaced with the composite separator prepared in the present example.
  • MPP trimeric nitrile pyrophosphate
  • LA132 trimeric nitrile pyrophosphate
  • the MPP and LA132 will be uniformly dispersed in deionized water to obtain the MPP slurry and LA132 slurry.
  • the above two kinds of the slurry were uniformly dispersed, and the solid content was controlled to be 45 wt% by deionized water to obtain a mixed slurry.
  • the mixed slurry was coated on both sides of a 20 ⁇ m polyethylene separator, and dried at 80 ° C to control the thickness of one side coating to be 3 ⁇ m.
  • the process of battery fabrication was the same as in Example 1, except that the composite separator of Example 1 was replaced with the composite separator prepared in the present example.
  • MPOP melamine phosphate
  • SBR melamine phosphate
  • the mixed slurry was coated on both sides of a 16 ⁇ m biaxially oriented polypropylene separator, and dried at 80 ° C to control the thickness of one side coating to be 4 ⁇ m.
  • the process of battery fabrication was the same as in Example 1, except that the composite separator of Example 1 was replaced with the composite separator prepared in the present example.
  • the mass fraction of active ingredient 98:2 the polyphosphate (APP) and polyvinylidene fluoride film (PVDF) were accurately weighed, and APP and PVDF were uniformly dispersed in NMP on the high speed disperser to obtain APP slurry. And the PVDF slurry, the above two kinds of the slurry were uniformly dispersed, and the solid content was controlled by NMP to be 30% by weight to obtain a mixed slurry.
  • APP polyphosphate
  • PVDF polyvinylidene fluoride film
  • the mixed slurry was coated on one side of a 16 ⁇ m polyethylene separator and dried at 65 ° C to control the thickness of one side coating to 4 ⁇ m.
  • the process of battery fabrication was the same as in Example 1, except that the composite separator of Example 1 was replaced with the composite separator prepared in the present example.
  • MPP trimeric nitrile pyrophosphate
  • MCA melamine cyanurate
  • SBR was added to the above slurry to be uniformly dispersed, and the solid content was controlled to be 55 wt% by deionized water to obtain a mixed slurry.
  • the mixed slurry was coated on one side of a 12 ⁇ m biaxially oriented polypropylene separator, and dried at 70 ° C to control a single-sided coating thickness of 5 ⁇ m.
  • the process of battery fabrication was the same as in Example 1, except that the composite separator of Example 1 was replaced with the composite separator prepared in the present example.
  • the mixed slurry was coated on both sides of a 12 ⁇ m polyethylene separator, and dried at 80 ° C to control the thickness of one side coating to be 3 ⁇ m.
  • the process of battery fabrication was the same as in Example 1, except that the composite separator of Example 1 was replaced with the composite separator prepared in the present example.
  • a battery was fabricated using a 25 ⁇ m biaxially oriented polypropylene separator.
  • the battery preparation process was the same as in Example 1, except that the composite separator of Example 1 was replaced with the separator provided in the comparative example.
  • a battery was fabricated using a 25 ⁇ m polyethylene separator.
  • the battery preparation process was the same as in Example 1, except that the composite separator of Example 1 was replaced with the separator provided in the comparative example.
  • the lithium ion battery composite separator prepared in Examples 1 to 8 and the films provided in the ratios 1 to 2 were respectively placed in an oven at a temperature of 80 ° C, 100 ° C, 120 ° C, 140 ° C, and 160 ° C for 2 hours, and the measurement was not performed.
  • the heat shrinkage rate of the composite separator at the same temperature is shown in Table 1 below. Table 1 shows the heat shrinkage rate of the separator at different temperatures.
  • the lithium ion battery composite separator prepared in Examples 1 to 8 and the film provided in the ratios 1 to 2 were respectively immersed in the electrolyte for 30 minutes, and the weight of the separator before and after the immersion was weighed in a closed space, and the liquid absorption amount per unit area of the separator was calculated. The results are shown in Table 2.
  • Table 2 shows the liquid absorption properties of different membranes.
  • the liquid absorbing performance of the lithium ion battery composite separator prepared in the examples was significantly better than that of the comparative example. Since the coatings coated on both sides of the composite membrane have voids, the porosity of the composite separator can be significantly improved, the defects of the polyolefin microporous membrane and the polar sheet of the pole piece can be compensated for, and the liquid retention capacity of the composite membrane can be improved, thereby increasing lithium.
  • the cycle performance of the ion battery was significantly better than that of the comparative example. Since the coatings coated on both sides of the composite membrane have voids, the porosity of the composite separator can be significantly improved, the defects of the polyolefin microporous membrane and the polar sheet of the pole piece can be compensated for, and the liquid retention capacity of the composite membrane can be improved, thereby increasing lithium.
  • the cycle performance of the ion battery was significantly better than that of the comparative example. Since the coatings coated on both sides of the composite membrane have voids, the porosity of the composite
  • the lithium ion battery functional separators prepared in Examples 1 to 8 have good wettability with the electrolyte, so that the battery has superior cycle performance.
  • the lithium ion batteries prepared in Examples 1 to 8 have superior safety performance.

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Abstract

本发明提供了一种锂离子电池复合隔膜，包括隔膜基体以及复合于所述隔膜基体表面的功能性涂层，所述功能性涂层由功能性物质和粘合剂制备而成，所述功能性物质选自含磷化合物、含氮类化合物和无机硅类化合物中的一种或多种。本发明提供的锂离子电池复合隔膜在隔膜基体表面涂覆了一层功能性涂层，该功能性涂层在锂离子电池温度升高时，可以快速吸收电池的多余热量，作为反应熵，自发地响应化学反应，在隔膜表面生成保护层，一方面可以有效抑制电池的温度的继续升高，减少隔膜的热收缩，另一方面可以钝化电池阴阳极的活性层，从根源上控制电池的安全隐患，保障电池的安全性。

Description

一种锂离子电池复合隔膜及其制备方法以及一种锂离子电池
本申请要求于2015年10月14日提交中国专利局、申请号为201510660432.X、发明名称为“一种锂离子电池复合隔膜及其制备方法以及一种锂离子电池”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
本发明属于锂离子电池技术领域，具体涉及一种锂离子电池复合隔膜及其制备方法以及一种锂离子电池。
背景技术
电池隔膜是指在电池正极和负极之间一层薄的多孔材料，是电池中非常关键的部分，对电池的安全性和成本有直接影响。它具有高离子渗透率和好的机械强度，并对体系例如电池的电解液中所用化学物质和溶剂具有长期稳定性。典型的有机隔膜是聚烯烃微孔膜，如聚乙烯微孔膜或聚丙烯微孔膜。由于聚烯烃自身的化学组成结构以及成型工艺，决定了它的物理和化学性能，造成了它在锂离子动力电池隔膜应用方面存在一些缺陷。
聚烯烃微孔膜用于电池隔膜主要存在的问题有：(1)聚烯烃作为非极性材料，与强极性的电解液亲和性差，造成了它的保液能力差；(2)聚烯烃微孔膜多采用机械拉伸致孔，或机械拉伸后有机溶剂萃取致孔，再通过热定型制得。最终造成该膜具有形状记忆效应，在温度较高时，隔膜趋向于恢复拉伸前膜的形状，导致较大的热收缩。虽然聚烯烃的熔化温度较低，基材易在温度超过165℃以上产生熔化，使微孔消失，阻断离子传导即所谓的熔断保护效应。但由于微孔聚烯烃膜发生熔化时，也伴随着体积收缩，膜面积缩小，使隔膜失去正负极之间的阻隔作用，从而导致电池内部正负极发生短路，引起电池燃烧甚至爆炸，产生安全隐患。
如何提高锂离子电池的安全性是本行业的重要课题，也是迫在眉睫的技术关键难题。造成锂离子电池发生安全隐患的主要原因是电池发生不可 逆的电化学副反应产生的热失控所致。因此，提高隔膜的热稳定性是锂离子电池安全性的重要保障。
行业内用来改善隔膜的热稳定性的途径主要是借助耐高温物质的物理性质，在聚烯烃的表面涂覆耐高温的无机物如三氧化二铝以及耐高温有机物如芳纶等，或开发耐高温的隔膜基体如聚酰亚胺隔膜等。但并不能阻止电池温度的进一步升高，无法高效地保障电池的安全性。
发明内容
有鉴于此，本发明要解决的技术问题在于提供一种锂离子电池复合隔膜及其制备方法以及一种锂离子电池，采用本发明提供的锂离子电池复合隔膜可以抑制电池温度升高，保障电池的安全性。
本发明提供了一种锂离子电池复合隔膜，包括隔膜基体以及复合于所述隔膜基体表面的功能性涂层，所述功能性涂层由功能性物质和粘合剂制备而成，所述功能性物质选自含磷化合物、含氮化合物和无机硅类化合物中的一种或多种。
优选的，所述功能性物质选自季戊四醇三聚氰胺磷酸酯及其盐类、聚磷酸铵、聚磷酰胺类化合物、有机磷腈聚合物、聚硅氧烷类化合物和硫脲类化合物中的一种或多种。
优选的，所述功能性物质选自三聚氰胺氰尿酸盐、季戊四醇三聚氰胺磷酸酯、多聚磷酸铵、聚二甲基硅氧烷和三聚氰胺焦磷酸盐中的一种或多种。
优选的，所述功能性物质和粘合剂的质量比为(90～99)：(1～10)。
优选的，所述功能性涂层的单面厚度为3～6μm。
优选的，所述隔膜基体选自聚烯烃微孔膜或聚烯烃基陶瓷膜。
优选的，所述粘结剂为聚偏氟乙烯及其共聚物、丙烯酸及其共聚物、丙烯酸酯及其共聚物、聚乙烯醇、羧甲基纤维和聚氨酯中的一种或多种。
本发明还提供了一种锂离子电池复合隔膜的制备方法，包括以下步骤：
A)将功能性物质和粘合剂分散于溶剂中，得到混合浆料，所述功能 性物质选自含磷化合物、含氮类化合物和无机硅类化合物中的一种或多种；
B)将所述混合浆料涂覆于隔膜基体表面，烘干，得到锂离子电池复合隔膜。
优选的，所述涂覆的方式选自转移涂覆、浸涂、刮涂、凹版涂覆、喷涂或丝网印刷。
本发明还提供了一种锂离子电池，包括正极、负极、隔膜和电解液，所述隔膜为上述锂离子电池复合隔膜。
优选的，所述正极的活性物质选自LiFePO4、LiMn2O4、LiCoO2、LiV2O5、LiNiO2、LiNi(1-x-y)CoxAlyO2、LiNi(1-m-n)ComMnnO2和LiCozNi(1-z)O2材料中的一种或多种，其中，0≤x≤1，0≤y≤1，x+y＝1；0≤m≤1，0≤n≤1，m+n＝1；0≤z≤1。
与现有技术相比，本发明提供了一种锂离子电池复合隔膜，包括隔膜基体以及复合于所述隔膜基体表面的功能性涂层，所述功能性涂层由功能性物质和粘合剂制备而成，所述功能性物质选自含磷化合物、含氮类化合物和无机硅类化合物中的一种或多种。本发明提供的锂离子电池复合隔膜在隔膜基体表面涂覆了一层功能性涂层，该功能性涂层在锂离子电池温度升高时，可以快速吸收电池的多余热量，作为反应熵，自发地响应化学反应，在隔膜表面生成保护层，一方面可以有效抑制电池的温度的继续升高，减少隔膜的热收缩，另一方面可以钝化电池阴阳极的活性层，从根源上控制电池的安全隐患，保障电池的安全性。另外，由于本发明的功能涂层硬度较小，可以减少电池制作过程中的工艺损耗，从而降低电池的生产成本。
结果表明，本发明提供的锂离子电池复合隔膜在不同的温度下均表现出较小的热收缩，具有良好的热稳定性；所述锂离子电池复合隔膜在30分钟内的吸液量为61～89g/m2；将所述复合隔膜制备成锂离子电池，其在1500个循环周期内的容量保持率＞90％，并且进行电池安全测试时，具有优越的安全性能。
具体实施方式
本发明提供了一种锂离子电池复合隔膜，包括隔膜基体以及复合于所述隔膜基体表面的功能性涂层，所述功能性涂层由功能性物质和粘合剂制备而成，所述功能性物质选自含磷化合物、含氮类化合物和无机硅类化合物中的一种或多种。
本发明提供的锂离子电池隔膜包括隔膜基体。本发明对所述锂离子电池的隔膜基体并没有特殊限制，本领域技术人员公知的可用于锂离子电池的隔膜基体即可。在本发明中，所述隔膜基体优选为聚烯烃微孔膜或聚烯烃基陶瓷膜。本发明所述的聚烯烃微孔膜可以是聚丙烯微孔膜，也可以是聚乙烯微孔膜，也可以是不同种类的聚烯烃微孔膜的复合薄膜。本发明所述的聚烯烃基陶瓷膜中所述陶瓷材料优选为氧化铝或勃姆石。在本发明的一些具体实施方式中，所述隔膜基体为聚丙烯微孔膜；在本发明的另一些具体实施方式中，所述隔膜基体为聚乙烯微孔膜。在本发明的另一些具体实施方式中，所述隔膜基体为聚乙烯基陶瓷隔膜；在本发明的另一些具体实施方式中，所述隔膜基体为聚丙烯基陶瓷隔膜。在本发明中，所述隔膜基体的厚度优选为10～60μm，优选为10～55μm，更优选为15～50μm，最优选为12～25μm。
本发明提供的锂离子电池隔膜还包括复合于所述隔膜基体表面的功能性涂层，所述功能性涂层由功能性物质和粘合剂制备而成。
本发明提供的功能性涂层包括功能性物质，所述用于制备锂离子电池隔膜表面功能性涂层的功能性物质在电池温度升高时，可以吸收电池的热量，作为反应熵，自发地响应化学反应，在隔膜表面生成保护层。在本发明中，所述功能性物质选自含磷化合物、含氮化合物和无机硅类化合物中的一种或多种。
优选的，所述功能性物质选自季戊四醇三聚氰胺磷酸酯及其盐类、聚磷酸铵、聚磷酰胺类化合物、有机磷腈聚合物、聚硅氧烷类化合物和硫脲类化合物中的一种或多种。
更优选的，所述功能性物质选自三聚氰胺氰尿酸盐及其衍生物、季戊四醇三聚氰胺磷酸酯及其衍生物、多聚磷酸铵及其衍生物、聚二甲基硅氧烷及其衍生物和三聚氰胺焦磷酸盐及其衍生物中的一种或多种。
最优选的，所述功能性物质选自三聚氰胺氰尿酸盐、季戊四醇三聚氰胺磷酸酯、多聚磷酸铵、聚二甲基硅氧烷和三聚氰胺焦磷酸盐中的一种或多种。
在本发明的一些具体实施方式中，所述功能性物质选自三聚氰胺氰尿酸盐(MCA)；在本发明的另一些具体实施方式中，所述功能性物质选自季戊四醇三聚氰胺磷酸酯(PPMS)；在本发明的另一些具体实施方式中，所述功能性物质选自三聚腈胺焦磷酸盐(MPP)；在本发明的另一些具体实施方式中，所述功能性物质选自三聚氰胺磷酸酯(MPOP)；在本发明的另一些具体实施方式中，所述功能性物质选自多聚磷酸铵(APP)；在本发明的另一些具体实施方式中，所述功能性物质选自三聚腈胺焦磷酸盐(MPP)和三聚氰胺氰尿酸盐(MCA)的混合物；在本发明的另一些具体实施方式中，所述功能性物质选自聚二甲基硅氧烷(PDMS)包覆的多聚磷酸铵(APP)颗粒，其中，所述聚二甲基硅氧烷与多聚磷酸铵的质量比优选为80:15。本发明对上述包覆的方法并没有特殊限制，优选按照下述方法进行包覆：
将聚二甲基硅烷和多聚磷酸铵在高速分散机上以10～80m/s的线速度快速搅拌15～60min，得到聚二甲基硅氧烷包覆的多聚磷酸铵颗粒(PDMS-APP)。
本发明提供的功能性涂层还包括粘结剂，所述粘结剂选自聚偏氟乙烯及其共聚物、丙烯酸及其共聚物、丙烯酸酯及其共聚物、聚乙烯醇、羧甲基纤维和聚氨酯中的一种或多种，优选为聚偏二氟乙烯膜(PVDF)、丁苯橡胶(SBR)和LA132水性粘合剂中的一种或多种。本发明所用的粘结剂可与隔膜基体紧密粘合，从而该粘结剂就保证了功能性涂层与隔膜基体的紧密粘结。两层粘结紧密，避免在振动、弯曲或者折叠过程中，出现脱粉现象，保障电池充放电过程中电流的均匀性。
在本发明中，所述功能性物质和粘合剂的质量比为(80～99)：(1～20)，优选为(90～99)：(1～10)。在本发明中的一些具体实施方式中，所述功能性物质和粘合剂的质量比为96:4；在本发明的另一些具体实施方式中，所述功能性物质和粘合剂的质量比为97:3；在本发明的另一些具体实施 方式中，所述功能性物质和粘合剂的质量比为98:2，在本发明的另一些具体实施方式中，所述功能性物质和粘合剂的质量比为95:5，在本发明的另一些具体实施方式中，所述功能性物质和粘合剂的质量比为95.5:4.5。
在本发明中，所述功能性涂层可以复合于所述隔膜基体的单面，也可以复合于所述隔膜基体的双面。
本发明所述的功能性涂层的单面厚度为2～15μm，优选为3～6μm。在本发明的一些具体实施方式中，所述涂层的厚度为3μm；在本发明的另一些具体实施方式中，所述涂层的厚度为4μm；在本发明的另一些具体实施方式中，所述涂层的厚度为5μm。
在本发明中，所述锂离子电池复合隔膜的厚度为12～75μm，优选为15～70μm，更优选为15～37μm。
本发明还提供了上述锂离子电池复合隔膜的制备方法，包括以下步骤：
A)将功能性物质和粘合剂分散于溶剂中，得到混合浆料，所述功能性物质包括含磷化合物、含氮类化合物和无机硅类化合物中的一种或多种；
B)将所述混合浆料涂覆于隔膜基体表面，烘干，得到锂离子电池复合隔膜。
本发明首先将功能性物质和粘合剂分散于溶剂中，得到混合浆料。本发明对所述分散的方法并没有特殊限制，本领域技术人员公知的分散方法即可。在本发明中，优选按照如下方法进行分散：
在高速分散机中，将功能性物质和粘合剂分别分散于溶剂中后再混合，得到混合浆料。
所述高速分散机的线速度优选为以10～80m/s，分散时间优选为10min～90min。所述溶剂包括但不限于去离子水、乙醇、苯、甲苯、NMP和丙酮中的一种或多种。在本发明的一些具体实施方式中，所述溶剂优选为去离子水或NMP。制备得到的混合浆料后，采用溶剂调节混合浆料中的固含量，最终控制混合浆料中的固含量为30wt％～60wt％，优选为35wt％～50wt％，本发明所用的调节混合浆料中固含量的溶剂包括但不限 于去离子水、乙醇、苯、甲苯、NMP和丙酮中的一种或多种。
得到混合浆料后，将所述混合浆料涂覆于隔膜基体表面，烘干，得到锂离子电池复合隔膜。
本发明对所述混合浆料涂覆于隔膜基体表面的方法并没有特殊限制，本领域技术人员公知的涂覆方法即可。在本发明中，优选采用转移涂覆、浸涂、刮涂、凹版涂覆、喷涂或丝网印刷。
将所述混合浆料涂覆于隔膜基体表面后，进行烘干，得到锂离子电池复合隔膜。本发明对所述烘干的方式并没有特殊限制，本领域技术人员公知的烘干方法即可。在本发明中，所述烘干的温度优选为40～90℃。
本发明还提供了一种锂离子电池，包括正极、负极、隔膜和电解液，所述隔膜选自上述锂离子电池复合隔膜。本发明对所述正极、负极以及电解液的种类并没有特殊限制，本领域技术人员公知的锂离子电池正极、负极以及电解液的种类即可。
在本发明中，所述正极的活性物质包括但不限于LiFePO4、LiMn2O4、LiCoO2、LiV2O5、LiNiO2、LiNi(1-x-y)CoxAlyO2、LiNi(1-m-n)ComMnnO2和LiCozNi(1-z)O2材料中的一种或多种，其中，0≤x≤1，0≤y≤1，x+y＝1；0≤m≤1，0≤n≤1，m+n＝1；0≤z≤1。
所述负极活性物质包括但不限于石墨、硬碳、钛酸锂和软碳中的一种或多种。
本发明提供的锂离子电池复合隔膜，借助其功能涂层耐高温的物理性能，可增加隔膜的热稳定性，减少隔膜的热收缩。在电池温度升高时，初步保障电池的安全性，使电池不会迅速发生内部短路等安全隐患。
本发明提供的锂离子电池复合隔膜，借助其功能涂层优良的化学性能，在电池温度升高后，功能涂层可以快速吸收电池的多余热量，作为反应熵，自发地响应化学反应，生成保护层。一方面，有效抑制电池的温度的继续升高，另一方面，钝化电池阴阳极的活性层，从根源上控制电池的安全隐患，保障电池的安全性。
另外，由于本发明的功能涂层硬度较小，可以减少电池制作过程中的工艺损耗，从而降低电池的生产成本。
结果表明，本发明提供的锂离子电池复合隔膜在不同的温度下均表现出较小的热收缩，具有良好的热稳定性；所述锂离子电池复合隔膜在30分钟内的吸液量为61～89g/m2；将所述复合隔膜制备成锂离子电池，其在1500个循环周期内的容量保持率＞90％，并且进行电池安全测试时，具有优越的安全性能。
为了进一步理解本发明，下面结合实施例对本发明提供的锂离子电池复合隔膜及其制备方法以及锂离子电池进行说明，本发明的保护范围不受以下实施例的限制。
实施例1
a.混合浆料的制备
按照96:4的质量比，准确称取三聚氰胺氰尿酸盐(MCA)、聚偏二氟乙烯膜(PVDF)。在高速分散机上分别将MCA和PVDF均匀分散于溶剂N-甲基吡咯烷酮(NMP)中，得到MCA浆料以及PVDF浆料，再将两种浆料搅拌均匀，并通过溶剂NMP控制浆料中的固含量为50wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在25μm的双向拉伸聚丙烯隔膜陶瓷隔膜的聚丙烯一面，在80℃下烘干，得到涂层的厚度为4μm，得到功能性涂层/双向拉伸聚丙烯薄膜/陶瓷层的复合隔膜。其中，陶瓷层为纯度为99.999％的纳米氧化铝。
c.电池制作
1)正极的制备：向溶剂NMP中加入质量分数分别为93wt％的活性材料LiNi1/3Co1/3Mn1/3O2、4wt％的导电剂炭黑和3wt％的粘结剂PVDF，混合均匀制得三元正极浆料，将正极浆料均匀涂覆在厚度为20μm的正极集流体Al箔上，干燥得到正极，辊压备用；
2)负极的制备：向溶剂去离子水中加入质量分数分别为95wt％的负极活性物质石墨粉，2wt％的导电剂炭黑、1wt％的增稠剂CMC(羧甲基纤维素钠)和2wt％的粘结剂SBR(丁苯橡胶)，混合均匀得到负极浆料， 将负极浆料均匀涂覆在厚度为10μm的负极集流体Cu箔上，干燥得到负极，辊压备用；
3)锂离子电池的组装：将功能隔膜、正极和负极叠片形成组件，其中功能涂层贴近电池的正极。
4)电解液的注入：向锂离子电池组件中注入电解液，得到锂离子二次电池。所述电解液为LiPF6在EC、EMC和DMC组成的体系中，所述LiPF6的浓度为1mol/L，EC、EMC和DMC的体积比为1∶1∶1。
实施例2
a.混合浆料的制备
按照98:2的质量比，准确称取季戊四醇三聚氰胺磷酸酯(PPMS)和聚偏二氟乙烯膜(PVDF)。在高速分散机上分别将PPMS和PVDF均匀分散于溶剂NMP中，得到PPMS浆料和PVDF浆料，再将上述两种浆料分散均匀，并通过溶剂NMP调节浆料中固含量为39wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在25μm的聚乙烯基陶瓷隔膜的聚乙烯一面，在65℃下烘干，控制涂覆厚度为3μm，得到功能性涂层/聚乙烯薄膜/陶瓷层的复合隔膜。其中，陶瓷层为纯度为99.999％的纳米氧化铝。
c.电池制作
电池制作的过程同实施例1，仅是将实施例1中的复合隔膜替换为本实施例制备得到的复合隔膜即可。
实施例3
a.混合浆料的制备
按照有效成分80:15:5的质量比准确称取多聚磷酸铵(APP)、聚二甲基硅氧烷(PDMS)和丁苯橡胶(SBR)，将聚二甲基硅烷和多聚磷酸铵在高速分散机上以50m/s的线速度快速搅拌30min，得到PDMS包覆的APP颗粒(PDMS-APP)。在高速分散机上将PDMS-APP均匀分散于去离子水中，再将SBR加入上述混合液中，分散均匀，通过添加去离子水浆料中 控制固含量为60wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在20μm的双向拉伸聚丙烯基陶瓷隔膜的聚丙烯一面，在70℃下烘干，得到涂覆的厚度为5μm，得到功能性涂层/双向拉伸聚丙烯薄膜/陶瓷层的复合隔膜。其中，陶瓷层为纯度为99.999％的纳米氧化铝。
c.电池制作
电池制作的过程同实施例1，仅是将实施例1中的复合隔膜替换为本实施例制备得到的复合隔膜即可。
实施例4
a.混合浆料的制备
按照有效成分95.5：4.5的质量分数准确称取三聚腈胺焦磷酸盐(MPP)和LA132，在高速分散机上将分别将MPP和LA132均匀分散于去离子水中，得到MPP浆料和LA132浆料，再将上述两种浆料分散均匀，并通过去离子水控制固含量为45wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在20μm的聚乙烯隔膜的双面，在80℃下烘干，控制单面涂覆厚度为3μm。
c.电池制作
电池制作的过程同实施例1，仅是将实施例1中的复合隔膜替换为本实施例制备得到的复合隔膜即可。
实施例5
a.混合浆料的制备
按照有效成分97：3的质量分数准确称取三聚氰胺磷酸酯(MPOP)和SBR，在高速分散机上将分别将MPOP均匀分散于去离子水中，将SBR加入上述浆料分散均匀，并通过去离子水控制固含量为40wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在16μm的双向拉伸聚丙烯隔膜的双面，在80℃下烘干，控制单面涂覆厚度为4μm。
c.电池制作
电池制作的过程同实施例1，仅是将实施例1中的复合隔膜替换为本实施例制备得到的复合隔膜即可。
实施例6
a.混合浆料的制备
按照有效成分98：2的质量分数准确称取多聚磷酸铵(APP)和聚偏二氟乙烯膜(PVDF)，在高速分散机上将分别将APP和PVDF均匀分散于NMP中，得到APP浆料和PVDF浆料，再将上述两种浆料分散均匀，并通过NMP控制固含量为30wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在16μm的聚乙烯隔膜的单面，在65℃下烘干，控制单面涂覆厚度为4μm。
c.电池制作
电池制作的过程同实施例1，仅是将实施例1中的复合隔膜替换为本实施例制备得到的复合隔膜即可。
实施例7
a.混合浆料的制备
按照有效成分50：45：5的质量分数准确称取三聚腈胺焦磷酸盐(MPP)、三聚氰胺氰尿酸盐(MCA)和SBR，在高速分散机上将将MPP和MCA均匀分散于去离子水中，再将SBR加入上述浆料分散均匀，并通过去离子水控制固含量为55wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在12μm的双向拉伸聚丙烯隔膜的单面，在70℃下烘干，控制单面涂覆厚度为5μm。
c.电池制作
电池制作的过程同实施例1，仅是将实施例1中的复合隔膜替换为本实施例制备得到的复合隔膜即可。
实施例8
a.混合浆料的制备
按照有效成分50：47：3的质量分数准确称取多聚磷酸铵(APP)、三聚氰胺氰尿酸盐(MCA)和PVDF，在高速分散机上将MPP和MCA均匀分散于NMP中，再将PVDF加入上述浆料分散均匀，并通过NMP控制固含量为35wt％，得到混合浆料。
b.复合隔膜的制备
将混合浆料涂覆在12μm的聚乙烯隔膜的双面，在80℃下烘干，控制单面涂覆厚度为3μm。
c.电池制作
电池制作的过程同实施例1，仅是将实施例1中的复合隔膜替换为本实施例制备得到的复合隔膜即可。
对比例1
选用25μm双向拉伸聚丙烯隔膜制作电池，电池制备过程同实施例1，仅是将实施例1中的复合隔膜替换为本对比例提供的隔膜即可。
对比例2
选用25μm聚乙烯隔膜制作电池，电池制备过程同实施例1，仅是将实施例1中的复合隔膜替换为本对比例提供的隔膜即可。
实施例9
1、测定实施例1～8和对比例1～2提供的薄膜热收缩性
取实施例1～8制备的锂离子电池复合隔膜和比例1～2提供的薄膜分别置于温度为80℃、100℃、120℃、140℃、160℃的烘箱中2h，测定不 同温度下复合隔膜的热收缩率，结果详见下表1，表1为不同温度下隔膜的热收缩率。
表1 不同温度下隔膜的热收缩率
Figure PCTCN2015092663-appb-000001
从表1可以看出，实施例1～8制备的复合隔膜在不同的温度下均表现出较小的热收缩，具有良好的热稳定性。
2、测定实施例1～8和对比例1～2提供的薄膜的吸液性
取实施例1～8制备的锂离子电池复合隔膜和比例1～2提供的薄膜分别置于电解液中浸泡30min，在密闭空间内称量浸泡前后隔膜的重量，计算单位面积隔膜的吸液量，结果详见表2，表2为不同隔膜的吸液性能。
表2 不同隔膜的吸液性能
Figure PCTCN2015092663-appb-000002
从表2可以看出，实施例制备的锂离子电池复合隔膜的吸液性能明显优于对比例。由于涂覆在复合隔膜两面的涂层均具有空隙，能显著提高复合隔膜的孔隙率，弥补聚烯烃微孔膜和极片孔隙率低的缺陷，提高复合隔膜的保液能力，从而增大锂离子电池的循环性能。
3、测定电池的循环性能
测定实施例1～8和对比例1～2提供的锂离子电池在1C/1C不同循环周期的容量保持率，结果详见下表3，表3为应用不同隔膜的锂离子电池的循环性能。
表3 应用不同隔膜的锂离子电池的循环性能
Figure PCTCN2015092663-appb-000003
Figure PCTCN2015092663-appb-000004
由表3可知，实施例1～8制备的锂离子电池功能隔膜与电解液的浸润性较好，从而使电池具有优越的循环性能。
4、测定电池的倍率放电性能
测定实施例1～8和对比例1～2提供的锂离子电池在3C倍率下放电的容量保持率，结果详见下表4，表4为应用不同隔膜的锂离子电池的倍率放电性能。
表4 应用不同隔膜的锂离子电池的倍率性能
Figure PCTCN2015092663-appb-000005
5、测试电池的安全性能
采用GB/T 31485-2015的方法(电动汽车用动力蓄电池安全要求及试验方法)对实施例1～8和对比例1～2制备的电池进行安全性能测试，结果见表5，表5为电池安全测试结果。
表5 电池安全测试结果
Figure PCTCN2015092663-appb-000006
Figure PCTCN2015092663-appb-000007
从表5可以看出，实施例1～8制备的锂离子电池具有优越的安全性能。
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (11)

  1. 一种锂离子电池复合隔膜，其特征在于，包括隔膜基体以及复合于所述隔膜基体表面的功能性涂层，所述功能性涂层由功能性物质和粘合剂制备而成，所述功能性物质选自含磷化合物、含氮化合物和无机硅类化合物中的一种或多种。
  2. 根据权利要求1所述的复合隔膜，其特征在于，所述功能性物质选自季戊四醇三聚氰胺磷酸酯及其盐类、聚磷酸铵、聚磷酰胺类化合物、有机磷腈聚合物、聚硅氧烷类化合物和硫脲类化合物中的一种或多种。
  3. 根据权利要求2所述的复合隔膜，其特征在于，所述功能性物质选自三聚氰胺氰尿酸盐、季戊四醇三聚氰胺磷酸酯、多聚磷酸铵、聚二甲基硅氧烷和三聚氰胺焦磷酸盐中的一种或多种。
  4. 根据权利要求1所述的复合隔膜，其特征在于，所述功能性物质和粘合剂的质量比为(90～99)：(1～10)。
  5. 根据权利要求1所述的复合隔膜，其特征在于，所述功能性涂层的单面厚度为3～6μm。
  6. 根据权利要求1所述的复合隔膜，其特征在于，所述隔膜基体选自聚烯烃微孔膜或聚烯烃基陶瓷隔膜。
  7. 根据权利要求1所述的复合隔膜，其特征在于，所述粘结剂为聚偏氟乙烯及其共聚物、丙烯酸及其共聚物、丙烯酸酯及其共聚物、聚乙烯醇、羧甲基纤维和聚氨酯中的一种或多种。
  8. 一种锂离子电池复合隔膜的制备方法，其特征在于，包括以下步骤：
    A)将功能性物质和粘合剂分散于溶剂中，得到混合浆料，所述功能性物质选自含磷化合物、含氮类化合物和无机硅类化合物中的一种或多种；
    B)将所述混合浆料涂覆于隔膜基体表面，烘干，得到锂离子电池复合隔膜。
  9. 根据权利要求8所述的制备方法，其特征在于，所述涂覆的方式 选自转移涂覆、浸涂、刮涂、凹版涂覆、喷涂或丝网印刷。
  10. 一种锂离子电池，其特征在于，包括正极、负极、隔膜和电解液，所述隔膜为权利要求1～7所述的锂离子电池复合隔膜或权利要求8～9所述的制备方法制备得到的锂离子电池复合隔膜。
  11. 根据权利要求10所述的锂离子电池，其特征在于，所述正极的活性物质选自LiFePO4、LiMn2O4、LiCoO2、LiV2O5、LiNiO2、LiNi(1-x-y)CoxAlyO2、LiNi(1-m-n)ComMnnO2和LiCozNi(1-z)O2材料中的一种或多种，其中，0≤x≤1，0≤y≤1，x+y＝1；0≤m≤1，0≤n≤1，m+n＝1；0≤z≤1。
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