WO2022057674A1 - 一种隔膜及包括该隔膜的电池 - Google Patents

一种隔膜及包括该隔膜的电池 Download PDF

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WO2022057674A1
WO2022057674A1 PCT/CN2021/116800 CN2021116800W WO2022057674A1 WO 2022057674 A1 WO2022057674 A1 WO 2022057674A1 CN 2021116800 W CN2021116800 W CN 2021116800W WO 2022057674 A1 WO2022057674 A1 WO 2022057674A1
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ceramic coating
diaphragm
separator
heat
ceramic
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PCT/CN2021/116800
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English (en)
French (fr)
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张祖来
李素丽
艾新平
唐伟超
李俊义
徐延铭
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珠海冠宇电池股份有限公司
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Priority to EP21868499.1A priority Critical patent/EP4156401A1/en
Publication of WO2022057674A1 publication Critical patent/WO2022057674A1/zh
Priority to US18/146,598 priority patent/US20230125852A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • 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
    • 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
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/42—Acrylic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application belongs to the technical field of lithium ion batteries, and in particular relates to a separator and a battery including the separator.
  • lithium-ion secondary batteries With the popularity of 3C products and the rise of the electric vehicle market, the demand for lithium-ion secondary batteries is increasing. As a key component of lithium-ion secondary batteries, separators directly affect the safety, rate, cycle, and low-temperature discharge performance of lithium-ion secondary batteries.
  • the traditional solution to battery rate, low-temperature discharge and cycle performance is mainly to improve the porosity of the diaphragm base layer (such as polyethylene or polypropylene). , affecting the self-discharge and safety performance of the battery.
  • the diaphragm base layer such as polyethylene or polypropylene
  • the purpose of the present application is to provide a separator and a battery including the separator, the separator includes a separator base layer and a ceramic coating disposed on the surface of the separator base layer, A large number of micropores are formed inside: on the one hand, it can improve the porosity of the separator, improve the battery rate, residual liquid, low-temperature discharge and cycle performance; on the other hand, it can ensure that the needle punch strength, self-discharge and safety performance of the separator are not affected.
  • a diaphragm comprising a diaphragm base layer and a ceramic coating disposed on a first surface of the diaphragm base layer; wherein the ceramic coating comprises ceramic particles; the surface and/or interior of the ceramic coating has micropores,
  • the porosity of the ceramic coating is 40%-80%, and among the micropores, the volume of pores with a pore diameter of 0.1 micrometer or more accounts for 45-90% of the total pore volume, and the volume of pores with a pore diameter of 1.0 micrometers or more accounts for 45-90% of the total pore volume. 40-80% of the total pore volume.
  • the volume of pores having a pore size of 0.1 micrometers or more accounts for 45-90% of the total pore volume, exemplarily 45%, 50%, 55%, 60%, 65%, 70%, 75% of the total pore volume %, 80%, 85% or 90%; the volume of pores having a pore size of 1.0 microns or greater is 40-80% of the total pore volume, exemplarily 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%.
  • the pore size of the largest pores in the micropores does not exceed 10 microns.
  • the pore diameter of the smallest pores in the micropores is not less than 0.01 micrometer.
  • the total areal density of the separator is 9.4-10.0 g/m 2 .
  • the material system of the diaphragm base layer is selected from polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polynaphthalene system polymer, polyimide At least one of amine, polyamide, aramid and polyparaphenylene benzobisoxazole.
  • the porosity of the membrane base layer is 20%-80%, such as 20%, 30%, 40%, 50%, 60%, 70% or 80%.
  • the thickness of the membrane base layer is 5-50 ⁇ m, for example, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 40 ⁇ m or 50 ⁇ m.
  • the added amount of the ceramic particles is 80-97wt% of the total mass of the ceramic coating, such as 80wt%, 82wt%, 85wt%, 88wt%, 90wt%, 92wt%, 94wt%, 95wt%, 96wt% or 97wt%.
  • the ceramic coating further includes adjuvants including binders, thickeners and dispersants.
  • the addition amount of the binder is 1-10wt% of the total mass of the ceramic coating, such as 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% % or 10wt%;
  • the added amount of the thickener is 1-10wt% of the total mass of the ceramic coating, such as 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt% ;
  • the added amount of the dispersant is 1-5wt% of the total mass of the ceramic coating, such as 1wt%, 2wt%, 3wt%, 4wt% or 5wt%.
  • the binder is selected from polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene modification and its copolymer, polyimide, polyacrylonitrile, polymethyl methacrylate Ester, aramid resin, polyacrylic acid, styrene-butadiene rubber (SBR), polyvinyl alcohol and its copolymerization modified polyvinyl alcohol, polyvinyl acetate, polyacrylamide, phenolic resin, epoxy resin, water-based polyurethane, ethylene-acetic acid At least one of ethylene copolymer, polyacrylic copolymer, lithium polystyrene sulfonate, water-based silicone resin, nitrile-polyvinyl chloride blend, polyethylene oxide, styrene-acrylic latex or pure styrene latex.
  • polyimide polyacrylonitrile
  • aramid resin
  • the thickening agent is selected from at least one of butyl benzyl phthalate compounds, sodium carboxymethyl cellulose, cellulose derivatives, polyurethane or acrylates, or lithium carboxymethyl cellulose.
  • the dispersing agent is selected from at least one of polyvinylpyrrolidone, polyethylene glycol, sodium polyacrylate, sodium silicate, polyacrylate alcohol or ammonium citrate.
  • micropores on the surface and/or inside of the ceramic coating there are a large number of micropores on the surface and/or inside of the ceramic coating, and the formation of the micropores is due to adding a heat-sensitive polymer to the slurry for preparing the ceramic coating, and then performing heat treatment through a drying process. A ceramic coating with a large number of micropores on the surface and/or inside is obtained.
  • the heat-sensitive polymer is melted and separated from the system during the heat treatment, and there are a large number of micropores on the surface and/or inside of the ceramic coating.
  • the heat-sensitive polymer is selected from polyethylene, polystyrene, polymethyl methacrylate, polyacrylic acid-butadiene-styrene, polylactic acid, polyvinyl chloride, polyvinyl butyral, etc. or its monomers At least one of the modified copolymerized polymers.
  • thermosensitive polymer is preferably thermosensitive polymer microspheres, and the particle size of the thermosensitive polymer microspheres is 0.01 ⁇ m-10 ⁇ m.
  • the melting point of the heat-sensitive polymer is 60°C-150°C.
  • the ceramic particles are selected from one or both of alumina, boehmite, magnesium oxide, magnesium hydroxide, barium sulfate, barium titanate, zinc oxide, calcium oxide, silicon dioxide, silicon carbide, and nickel oxide. more than one species.
  • the weight ratio of the heat-sensitive polymer to the ceramic particles is (1-60):(99-40), such as (5-50):(95-50) , such as (10-45): (90-55), such as (15-40): (85-60), such as (20-30): (80-70).
  • the separator can be used in the field of lithium ion batteries.
  • the thickness of the ceramic coating is 1-10 ⁇ m, for example, 2-5 ⁇ m, such as 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m or 10 ⁇ m, the thickness of the ceramic coating layer It can be obtained by one coating or by multiple coating.
  • the average particle size of the ceramic particles is 0.01 ⁇ m-10 ⁇ m.
  • the diaphragm further includes a first glue layer disposed on the surface of the ceramic coating.
  • the diaphragm further includes a second glue coating layer disposed on a second surface of the diaphragm base layer opposite to the first surface.
  • the thicknesses of the first adhesive layer and the second adhesive layer are the same or different, and are selected from 1-5 ⁇ m.
  • the material system of the adhesive layer is selected from polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene modification and its copolymer, polyimide, polyacrylonitrile, polymethyl methacrylate Methyl acrylate, aramid resin, polyacrylic acid, styrene-butadiene rubber (SBR), polyvinyl alcohol and its copolymerization modified polyvinyl alcohol, polyvinyl acetate, polyacrylamide, phenolic resin, epoxy resin, water-based polyurethane, Ethylene-vinyl acetate copolymer, polyacrylic copolymer, lithium polystyrene sulfonate, water-based silicone resin, nitrile-polyvinyl chloride blend, polyethylene oxide, styrene-acrylic latex or pure styrene latex.
  • polyimide polyacrylonitrile
  • the present application also provides a method for preparing the above-mentioned diaphragm, the method comprising the steps of:
  • step b) adding a heat-sensitive polymer to the ceramic slurry obtained in step a) to obtain a modified ceramic slurry;
  • step b) Coating the modified ceramic slurry obtained in step b) on the first surface of the diaphragm base layer, drying, and heat treatment to prepare the diaphragm.
  • the method further comprises the following steps:
  • the mass ratio of the ceramic particles and the auxiliary agent is (80-97):(3-20).
  • the auxiliary agent includes a binder, a thickening agent and a dispersing agent.
  • the weight ratio of the thermosensitive polymer to the ceramic particles is (1-60):(99-40).
  • the coating method is, for example, spray coating, dip coating, gravure printing, extrusion coating, and transfer coating.
  • the drying temperature is 40-120° C., and the drying time is 20-600 s.
  • the temperature of the heat treatment is 0-20° C. higher than the melting point of the heat-sensitive polymer, and the time of the heat treatment is 2-10 minutes.
  • the present application also provides a lithium ion battery, the lithium ion battery comprising the above-mentioned separator.
  • the lithium ion battery further includes a positive electrode, a negative electrode and an electrolyte.
  • the present application provides a separator and a battery including the separator.
  • the porosity of the separator can be improved, and the battery rate, residual liquid volume, low-temperature discharge, long-term battery life, etc. can be improved. Cyclic performance; on the other hand, the needle punch strength of the diaphragm, self-discharge and safety performance are not affected.
  • Fig. 1 the structural representation of the diaphragm according to an embodiment of the present application
  • Figure 2 Scanning electron microscope image (500 times) of the ceramic coating in the separator of Example 1;
  • FIG. 3 Scanning electron microscope image of the ceramic coating in the separator of Example 1 (10,000 times);
  • FIG. 4 45°C cycle diagram of batteries prepared by the separators of Example 1 and Comparative Example 1;
  • FIG. 5 Rate discharge diagrams of batteries prepared from the separators of Example 1 and Comparative Example 1;
  • FIG. 7 Pore size distribution diagrams of the separators of Example 1 and Comparative Example 1.
  • the above-mentioned modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, dried at 60° C. for 1 min, and then treated at a high temperature of 120° C. for 5 minutes to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or the interior of the ceramic coating has micropores, the porosity of the ceramic coating is 55%, the pores with a pore size of 0.1 ⁇ m or more account for 85%, and the pores with a pore size of 1 ⁇ m or more. Pores accounted for 45% and the total areal density of the separator was 10.0 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the above modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, dried at 60° C. for 1 min, and then subjected to high temperature treatment at 122° C. for 5 minutes to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or interior of the ceramic coating has micropores, the porosity of the ceramic coating is 63%, the pores with a pore diameter of 0.1 ⁇ m or more account for 87%, and the pores with a pore diameter of 1 ⁇ m or more. Pores accounted for 55% and the total areal density of the membrane was 9.7 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the above-mentioned modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, dried at 60° C. for 1 minute, and then subjected to high temperature treatment at 124° C. for 5 minutes to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or interior of the ceramic coating has micropores, the porosity of the ceramic coating is 70%, the pores with a pore diameter of 0.1 ⁇ m or more account for 89%, and the pores with a pore diameter of 1 ⁇ m or more. Pores accounted for 65% and the total areal density of the membrane was 9.4 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the above modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, dried at 60° C. for 1 min, and then subjected to high temperature treatment at 120° C. for 7 minutes to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or the interior of the ceramic coating has micropores, the porosity of the ceramic coating is 60%, the pores with a pore size of 0.1 ⁇ m or more account for 88%, and the pores with a pore size of 1 ⁇ m or more. Pores accounted for 50% and the total areal density of the separator was 9.8 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the above-mentioned modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, dried at 60° C. for 1 minute, and then subjected to high temperature treatment at 118° C. for 9 minutes to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or interior of the ceramic coating has micropores, the porosity of the ceramic coating is 72%, the pores with a pore size of 0.1 ⁇ m or more account for 90%, and the pores with a pore size of 1 ⁇ m or more. Pores accounted for 55% and the total areal density of the membrane was 9.5 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the above modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, dried at 60° C. for 1 min, and then subjected to high temperature treatment at 120° C. for 7 minutes to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or the interior of the ceramic coating has micropores, the porosity of the ceramic coating is 55%, the pores with a pore size of 0.1 ⁇ m or more account for 85%, and the pores with a pore size of 1 ⁇ m or more. Pores accounted for 40% and the total areal density of the separator was 10.0 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the above-mentioned modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, dried at 60° C. for 1 minute, and then subjected to high temperature treatment at 130° C. for 4 minutes to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or the interior of the ceramic coating has micropores, the porosity of the ceramic coating is 55%, the pores with a pore size of 0.1 ⁇ m or more account for 85%, and the pores with a pore size of 1 ⁇ m or more. Pores accounted for 40% and the total areal density of the separator was 10.0 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the above modified ceramic slurry was coated on the first surface of the diaphragm base layer by microgravure, and dried at 60° C. for 1 min to obtain the diaphragm.
  • the thickness of the diaphragm base layer in the diaphragm is 9 ⁇ m
  • the material system of the diaphragm base layer is PE
  • the porosity is 40%.
  • the thickness of the ceramic coating in the separator is 3 ⁇ m, the surface and/or the interior of the ceramic coating has micropores, the porosity of the ceramic coating is 30%, the pores with a pore size of 0.1 ⁇ m or more account for 60%, and the pores with a pore size of 1 ⁇ m or more. Pores accounted for 15% and the total areal density of the separator was 10.0 g/m 2 .
  • the above-mentioned separator, the positive electrode and the negative electrode are laminated or wound to prepare a lithium ion battery cell, and a high performance lithium ion battery is obtained after baking, liquid injection, formation and packaging.
  • the lithium-ion batteries prepared in Examples 1-7 and Comparative Example 1 were subjected to voltage test and internal resistance test.
  • the test process was to fully charge the lithium-ion batteries prepared in Examples 1-7 and Comparative Example 1 at 25°C and 50°C.
  • the voltage and internal resistance of the battery in a fully charged state were tested with a voltage resistance meter (Amber-Applent, model AT526B), and the results are shown in Table 1.
  • Example 1 Sample serial number Lithium-ion battery average voltage Lithium-ion battery internal resistance Example 1 4.2011V 10.23m ⁇ Example 2 4.2022V 9.67m ⁇ Example 3 4.2017V 8.42m ⁇ Example 4 4.2015V 9.88m ⁇ Example 5 4.2009V 7.75m ⁇ Example 6 4.2012V 10.33m ⁇ Example 7 4.2022V 10.28m ⁇ Comparative Example 1 4.2015V 12.55m ⁇
  • Example 1 The lithium-ion batteries prepared in Example 1 and Comparative Example 1 were subjected to charge-discharge cycle and rate performance tests, and the charge-discharge cycle test was performed using the system of 1C charge/1C discharge; the rate performance test was performed using 0.2C charge/0.2C, 0.5C , 1C, 1.5C, and 2C discharge regimes were tested.
  • the results are shown in Figure 4 and Figure 5. It can be seen from Figure 4 and Figure 5 that the battery of Example 1 can not only maintain a good capacity retention rate in the later cycle of the cycle , and can maintain a good capacity retention rate under high-rate discharge.
  • the lithium ion batteries prepared in Examples 1-7 and Comparative Example 1 were subjected to residual liquid amount, and the lithium ion battery separators prepared in Examples 1-7 and Comparative Example 1 were subjected to separator needle punch strength and ionic conductivity tests.
  • the residual liquid amount is mainly obtained by weighing the cell weight M1 before liquid injection, the trimming weight M2, and the cell weight M3 after two sealing, to obtain the residual liquid amount M3+M2-M1.
  • the test method of acupuncture strength is as follows: a steel needle with a spherical needle with a diameter of 1 mm is used to pierce the septum at a speed of 100 mm/min, and the maximum force during the piercing process is recorded as the acupuncture strength.
  • the ionic conductivity test method is as follows: put the sample into the electrolyte at a temperature of 23 ⁇ 2°C, keep it sealed, and soak it for 2h.
  • ⁇ the ionic conductivity of the sample, in Siemens/meter (S/cm); d—the thickness of the test, in micrometers ( ⁇ m); k—the slope of the curve; S——the test area of the diaphragm, The unit is square centimeters (cm 2 ).
  • Example 1 7.978 10.66 528
  • Example 2 8.109 12.45 535
  • Example 3 8.411 13.74
  • Example 4 8.045 11.98 518
  • Example 5 8.604 15.79 507
  • Example 6 7.898 10.53 502
  • Example 7 7.935 9.86 498 Comparative Example 1 7.503 3.64 511
  • the amount of residual liquid in the separators of Examples 1-7 has a certain increase, which is mainly due to the increase in the porosity of the separators, and there is more space for storing electrolyte;
  • the ionic conductivity of the separator has been significantly improved, which is mainly due to the obvious increase in the porosity of the porous material ceramic layer.
  • the separators of Examples 1-7 can be used in long-term battery cycles, rate performance, and low-temperature performance. Significant improvement.
  • the needle punch strength test results of the diaphragms of Examples 1-7 are equivalent to the needle punch strength test results of the diaphragms of Comparative Example 1, which shows that the diaphragms of the present application can meet the requirements of the needle punch strength, that is, they also achieve better safety performance. .

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Abstract

本申请提供了一种隔膜及包括该隔膜的电池，所述隔膜包括隔膜基层和设置在隔膜基层的第一表面的陶瓷涂层；其中，所述陶瓷涂层包括陶瓷颗粒；所述陶瓷涂层的表面和/或内部具有微孔，所述陶瓷涂层的孔隙率为40％-80％，所述微孔中，孔径为0.1微米以上的孔的体积占总孔体积的45-90％，孔径为1.0微米以上的孔的体积占总孔体积的40-80％。本申请通过在陶瓷涂层表面和/或内部形成大量微孔，一方面提升隔膜孔隙率，提升电池倍率、残液量、低温放电、长循环性能；另一方面保证隔膜针刺强度，自放电和安全性能不受影响。

Description

一种隔膜及包括该隔膜的电池
本申请要求于2020年09月16日提交中国专利局、申请号为202010975419.4、申请名称为“一种隔膜及包括该隔膜的电池”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
本申请属于锂离子电池技术领域，具体涉及一种隔膜及包括该隔膜的电池。
背景技术
随着3C产品的普及和电动汽车市场的兴起，对锂离子二次电池的需求越来越高。隔膜作为锂离子二次电池的关键构件，直接影响锂离子二次电池的安全、倍率、循环、低温放电等性能。
传统的解决电池倍率、低温放电和循环性能主要是通过提升隔膜基层(如聚乙烯或聚丙烯)的孔隙率，但随着隔膜基层孔隙率的提升，隔膜针刺强度、热收缩等性能会降低，影响电池的自放电、安全等性能。
因此需要提供一种既解决电池倍率、低温放电和循环性能，又不影响电池自放电、安全性能的隔膜。
发明内容
为了改善现有技术的不足，本申请的目的是提供一种隔膜及包括该隔膜的电池，所述隔膜包括隔膜基层和设置在隔膜基层表面的陶瓷涂层，通过在陶瓷涂层表面和/或内部形成大量微孔：一方面可以提升隔膜孔隙率，提升电池倍率、残液量、低温放电和循环性能；另一方面可以保证隔膜针刺强度、自放电和安全性能不受影响。
本申请目的是通过如下技术方案实现的：
一种隔膜，所述隔膜包括隔膜基层和设置在隔膜基层的第一表面 的陶瓷涂层；其中，所述陶瓷涂层包括陶瓷颗粒；所述陶瓷涂层的表面和/或内部具有微孔，所述陶瓷涂层的孔隙率为40％-80％，所述微孔中，孔径为0.1微米以上的孔的体积占总孔体积的45-90％，孔径为1.0微米以上的孔的体积占总孔体积的40-80％。
根据本申请，孔径为0.1微米以上的孔的体积占总孔体积的45-90％，示例性地占总孔体积的45％、50％、55％、60％、65％、70％、75％、80％、85％或90％；孔径为1.0微米以上的孔的体积占总孔体积的40-80％，示例性地占总孔体积的40％、45％、50％、55％、60％、65％、70％、75％或80％。
根据本申请，所述微孔中的最大孔的孔径不超过10微米。
根据本申请，所述微孔中的最小孔的孔径不小于0.01微米。
根据本申请，所述隔膜的总面密度为9.4-10.0g/m 2。
根据本申请，所述隔膜基层的材料体系选自聚乙烯、聚丙烯、聚对苯二甲酸乙二酯、聚对苯二甲酸丁二酯、聚苯乙烯、聚萘体系聚合物、聚酰亚胺、聚酰胺、芳纶和聚对苯撑苯并二恶唑中的至少一种。
根据本申请，所述隔膜基层的孔隙率为20％-80％，例如为20％、30％、40％、50％、60％、70％或80％。
根据本申请，所述隔膜基层的厚度为5-50μm，例如为5μm、10μm、15μm、20μm、25μm、30μm、40μm或50μm。
根据本申请，所述陶瓷颗粒的加入量为陶瓷涂层总质量的80-97wt％，如80wt％、82wt％、85wt％、88wt％、90wt％、92wt％、94wt％、95wt％、96wt％或97wt％。
根据本申请，所述陶瓷涂层还包括助剂，所述助剂包括粘结剂、增稠剂和分散剂。
根据本申请，所述粘结剂的加入量为陶瓷涂层总质量的1-10wt％，如1wt％、2wt％、3wt％、4wt％、5wt％、6wt％、7wt％、8wt％、9wt％或10wt％；
所述增稠剂的加入量为陶瓷涂层总质量的1-10wt％，如1wt％、2wt％、3wt％、4wt％、5wt％、6wt％、7wt％、8wt％、9wt％或10wt％；
所述分散剂的加入量为陶瓷涂层总质量的1-5wt％，如1wt％、2wt％、3wt％、4wt％或5wt％。
根据本申请，所述粘结剂选自聚四氟乙烯、聚偏氟乙烯、聚偏氟乙烯-六氟丙烯改性及其共聚物、聚酰亚胺、聚丙烯腈、聚甲基丙烯酸甲酯、芳纶树脂、聚丙烯酸、丁苯橡胶(SBR)、聚乙烯醇及其共聚改性聚乙烯醇、聚醋酸乙烯酯、聚丙烯酰胺、酚醛树脂、环氧树脂、水性聚氨酯、乙烯-醋酸乙烯共聚物、多元丙烯酸类共聚物、聚苯乙烯磺酸锂、水性有机硅树脂、丁腈-聚氯乙烯共混物、聚氧化乙烯、苯丙乳胶或纯苯乳胶中的至少一种。
根据本申请，所述增稠剂选自邻苯二甲酸丁苄酯类化合物、羧甲基纤维素钠、纤维素衍生物、聚氨酯或丙烯酸酯类或羧甲基纤维素锂中至少一种。
根据本申请，所述分散剂选自聚乙烯吡咯烷酮、聚乙二醇、聚丙烯酸钠、亚硅酸钠、聚丙烯醇或柠檬酸铵中的至少一种。
根据本申请，所述陶瓷涂层的表层和/或内部存在大量的微孔，微孔的形成是由于在制备陶瓷涂层的浆料中添加热敏聚合物，再通过干燥工艺进行热处理后制备得到表层和/或内部存在大量微孔的陶瓷涂层。
其中，热处理过程中热敏聚合物经熔融后从体系中分离，在陶瓷涂层的表层和/或内部存在大量的微孔。
其中，所述热敏聚合物选自聚乙烯、聚苯乙烯、聚甲基丙烯酸甲酯、聚丙烯酸-丁二烯-苯乙烯、聚乳酸、聚氯乙烯、聚乙烯丁醛等或其单体改性共聚的聚合物的至少一种。
其中，所述热敏聚合物优选为热敏聚合物微球，所述热敏聚合物微球的粒径为0.01μm-10μm。
其中，所述热敏聚合物的熔点为60℃-150℃。
其中，所述陶瓷颗粒选自氧化铝、勃姆石、氧化镁、氢氧化镁、硫酸钡、钛酸钡、氧化锌、氧化钙、二氧化硅、碳化硅、氧化镍中的一种或两种以上。
其中，制备陶瓷涂层的浆料中，所述热敏聚合物与所述陶瓷颗粒 的重量比为(1-60):(99-40)，如(5-50):(95-50)、如(10-45):(90-55)、如(15-40):(85-60)、如(20-30):(80-70)。
根据本申请，所述隔膜可以用于锂离子电池领域。
根据本申请，所述陶瓷涂层的厚度为1-10μm，例如为2-5μm，如1μm、2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm或10μm，所述厚度的陶瓷涂层可以是一次涂覆得到的，也可以是多次涂覆得到的。
根据本申请，所述陶瓷颗粒的平均粒径为0.01μm-10μm。例如为0.01μm、0.05μm、0.1μm、0.5μm、1μm、4μm、5μm、8μm或10μm。
根据本申请，所述隔膜还包括设置在陶瓷涂层表面的第一涂胶层。
根据本申请，所述隔膜还包括设置在隔膜基层与第一表面相对的第二表面的第二涂胶层。
根据本申请，所述第一涂胶层和第二涂胶层的厚度相同或不同，选自1-5μm。
根据本申请，所述涂胶层的材料体系选自聚四氟乙烯、聚偏氟乙烯、聚偏氟乙烯-六氟丙烯改性及其共聚物、聚酰亚胺、聚丙烯腈、聚甲基丙烯酸甲酯、芳纶树脂、聚丙烯酸、丁苯橡胶(SBR)、聚乙烯醇及其共聚改性聚乙烯醇、聚醋酸乙烯酯、聚丙烯酰胺、酚醛树脂、环氧树脂、水性聚氨酯、乙烯-醋酸乙烯共聚物、多元丙烯酸类共聚物、聚苯乙烯磺酸锂、水性有机硅树脂、丁腈-聚氯乙烯共混物、聚氧化乙烯、苯丙乳胶或纯苯乳胶。
本申请还提供上述隔膜的制备方法，所述方法包括如下步骤：
a)将陶瓷颗粒、水、任选地助剂混合，得到陶瓷浆料；
b)在步骤a)得到的陶瓷浆料中加入热敏聚合物，得到改性陶瓷浆料；
c)将步骤b)得到的改性陶瓷浆料涂覆在隔膜基层的第一表面，干燥，热处理，制备得到所述隔膜。
根据本申请，所述方法还包括如下步骤：
d)准备形成涂胶层的浆料，将所述涂胶层的浆料涂覆在隔膜基层的第二表面上，和/或涂覆在陶瓷涂层的表面上。
根据本申请，步骤a)中，所述陶瓷颗粒和助剂的质量比为(80-97):(3-20)。
根据本申请，步骤a)中，所述助剂包括粘结剂、增稠剂和分散剂。
根据本申请，步骤b)中，所述热敏聚合物与所述陶瓷颗粒的重量比为(1-60):(99-40)。
根据本申请，步骤c)中，所述涂覆的方式例如为喷涂、浸涂、凹版印刷、挤压涂覆、转移涂覆。
根据本申请，步骤c)中，所述干燥的温度为40-120℃，所述干燥的时间为20-600s。所述热处理的温度比热敏聚合物的熔点高0-20℃，所述热处理的时间为2-10min。
本申请还提供一种锂离子电池，所述锂离子电池包括上述的隔膜。
根据本申请，所述锂离子电池还包括正极、负极和电解液。
本申请的有益效果：
本申请提供了一种隔膜及包括该隔膜的电池，本申请通过在陶瓷涂层表面和/或内部形成大量微孔，一方面提升隔膜孔隙率，提升电池倍率、残液量、低温放电、长循环性能；另一方面保证隔膜针刺强度，自放电和安全性能不受影响。
附图说明
图1：本申请的一种实施方式所述的隔膜的结构示意图；
图2：实施例1的隔膜中的陶瓷涂层的扫描电镜图(500倍)；
图3：实施例1的隔膜中的陶瓷涂层的扫描电镜图(10000倍)；
图4：实施例1和对比例1的隔膜制备的电池的45℃循环图；
图5：实施例1和对比例1的隔膜制备的电池的倍率放电图；
图6：实施例1和对比例1的隔膜制备的电池的-20℃低温放电图；
图7：实施例1和对比例1的隔膜的孔径分布图。
具体实施方式
下文将结合具体实施例对本申请做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本申请，而不应被解释为对本申请保护范围的限制。凡基于本申请上述内容所实现的技术均涵盖在本申请旨在保护的范围内。
下述实施例中所使用的实验方法如无特殊说明，均为常规方法；下述实施例中所用的试剂、材料等，如无特殊说明，均可从商业途径得到。
实施例1
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
取10kg上述陶瓷浆料，加入0.2kg热敏聚合物微球(热敏聚合物微球的粒径为1.5μm，热敏温度为110℃)，得到改性陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min后再经120℃高温处理5min，得到隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为55％，孔径为0.1μm以上的孔占85％，孔径为1μm以上的孔占45％，隔膜总面密度为10.0g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
实施例2
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
取10kg上述陶瓷浆料，加入0.4kg热敏聚合物微球(热敏聚合物微球的粒径为1.5μm，热敏温度为110℃)，得到改性陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min后再经122℃高温处理5min，得到隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为63％，孔径为0.1μm以上的孔占87％，孔径为1μm以上的孔占55％，隔膜总面密度为9.7g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
实施例3
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
取10kg上述陶瓷浆料，加入0.6kg热敏聚合物微球(热敏聚合物微球的粒径为1.5μm，热敏温度为110℃)，得到改性陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min后再经124℃高温处理5min，得到隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为70％，孔径为0.1μm以上的孔占89％，孔径为1μm以上的孔占65％，隔膜总面密度为9.4g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
实施例4
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
取10kg上述陶瓷浆料，加入0.4kg热敏聚合物微球(热敏聚合物微球的粒径为1.0μm，热敏温度为110℃)，得到改性陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min后再经120℃高温处理7min，得到隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为60％，孔径为0.1μm以上的孔占88％，孔径为1μm以上的孔占50％，隔膜总面密度为9.8g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
实施例5
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
取10kg上述陶瓷浆料，加入0.6kg热敏聚合物微球(热敏聚合物微球的粒径为0.5μm，热敏温度为110℃)，得到改性陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min后再经118℃高温处理9min，得到隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为72％，孔径为0.1μm以上的孔占90％，孔径为1μm以上的孔占55％，隔膜总面密度为9.5g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
实施例6
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
取10kg上述陶瓷浆料，加入0.2kg热敏聚合物微球(热敏聚合物微球的粒径为1.0μm，热敏温度为100℃)，得到改性陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min后再经120℃高温处理7min，得到隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为55％，孔径为0.1μm以上的孔占85％，孔径为1μm以上的孔占40％，隔膜总面密度为10.0g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
实施例7
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
取10kg上述陶瓷浆料，加入0.2kg热敏聚合物微球(热敏聚合物微球的粒径为1.0μm，热敏温度为120℃)，得到改性陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min后再经130℃高温处理4min，得到所述隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为55％，孔径为0.1μm以上的孔占85％，孔径为1μm以上的孔占40％，隔膜总面密度为10.0g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
对比例1
将20kg氧化铝、0.32kg羧甲基纤维素钠、1kg聚甲基丙烯酸甲酯、0.1kg聚乙烯吡咯烷酮、78.58kg去离子水混合在一起，得到陶瓷浆料；
将上述改性陶瓷浆料通过微凹版涂覆在隔膜基层的第一表面，经60℃干燥1min，得到隔膜。
其中，隔膜中的隔膜基层的厚度为9μm，隔膜基层的材料体系为PE，孔隙率为40％。
隔膜中的陶瓷涂层的厚度为3μm，陶瓷涂层的表面和/或内部具有微孔，陶瓷涂层的孔隙率为30％，孔径为0.1μm以上的孔占60％，孔径为1μm以上的孔占15％，隔膜总面密度为10.0g/m 2。
将上述隔膜与正极、负极采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高性能锂离子电池。
测试例1
将实施例1-7、对比例1制备的锂离子电池进行电压测试和内阻测试，测试过程是将实施例1-7、对比例1制备的锂离子电池充满电后置于25℃、50％湿度的环境中，用电压内阻仪(安柏-Applent，型号AT526B)测试电池满电状态下的电压和内阻，结果如表1所示。
表1实施例1-7、对比例1的锂离子电池的电压测试和内阻测试结果
样品编号 锂离子电池平均电压 锂离子电池内阻
实施例1 4.2011V 10.23mΩ
实施例2 4.2022V 9.67mΩ
实施例3 4.2017V 8.42mΩ
实施例4 4.2015V 9.88mΩ
实施例5 4.2009V 7.75mΩ
实施例6 4.2012V 10.33mΩ
实施例7 4.2022V 10.28mΩ
对比例1 4.2015V 12.55mΩ
通过表1的数据得知，实施例1-7和对比例1制备的锂离子电池分选后，电压正常，但实施例1-7制备的锂离子电池相对对比例1制备的锂离子电池的内阻有明显降低，这主要是由于实施例1-7制备的隔膜的孔隙率高，能显著提升锂离子的通透性；且内阻的明显降低也有利于提升电池倍率、低温放电和长循环性能。
具体地：
将实施例1、对比例1制备的锂离子电池进行充放电循环和倍率性能测试，充放电循环测试采用1C充电/1C放电的制度进行测试；倍率 性能测试采用0.2C充电/0.2C、0.5C、1C、1.5C、2C放电的制度进行测试，结果如图4和图5所示，从图4和图5中可以看出，实施例1的电池不仅在循环后期能保持良好的容量保持率，而且在高倍率放电下也能保持很好的容量保持率。
通过对比实施例1-7、对比例1的实验结果，得出以下结论：
1)随着陶瓷涂层孔隙率的提升能够降低电池内阻，提升电池的倍率性能和循环性能；
2)实施例1-7中随着孔隙率的增加电池内阻降低明显。
测试例2：
将实施例1-7、对比例1制备的锂离子电池进行残液量、并对实施例1-7、对比例1制备的锂离子电池隔膜进行隔膜针刺强度和离子导通性测试。
其中，残液量主要是通过称量注液前的电芯重量M1，切边重量M2，二封后的电芯重量M3，得到残液量M3+M2-M1。针刺强度测试方法如下：将直径为1mm的球形针头的钢针，以100mm/min的速度刺穿隔膜，刺穿过程中记录最大的力作为针刺强度。离子导通性测试方法如下：将试样放入温度为23±2℃的电解液中，保持密封，浸泡2h。将电解液注入电阻测试模具中，并将其与化学工作站连接，设置测试参数。依次放入1层隔膜，测试其阻抗谱，再放入一层，测试其阻抗谱，直至放入4层，测量出四个阻抗谱图，并从阻抗谱图中分别读取1到4层时的阻值R1、R2、R3和R4。以层数为横坐标，隔膜阻值为纵坐标作曲线，求出曲线的斜率和线性拟合度，当线性拟合度大于0.99时，隔膜的离子电导率按照如下公式进行计算：
σ＝d/1000kS
式中：
σ——试样的离子电导率，单位为西门子/米(S/cm)；d——试验的厚度，单位为微米(μm)；k——曲线的斜率；S——隔膜的测试面积，单位为平方厘米(cm 2)。
表2实施例1-7、对比例1制备的锂离子电池的残液量、隔膜的隔膜针刺强度和离子导通性的测试结果
  残液量*g 离子导通率*10 -4Scm -1 隔膜针刺强度g
实施例1 7.978 10.66 528
实施例2 8.109 12.45 535
实施例3 8.411 13.74 510
实施例4 8.045 11.98 518
实施例5 8.604 15.79 507
实施例6 7.898 10.53 502
实施例7 7.935 9.86 498
对比例1 7.503 3.64 511
从测试结果来看，实施例1-7的隔膜中的残液量有一定提升，这主要是由于隔膜的孔隙率提升，有更多的存储电解液的空间；同时，实施例1-7的隔膜的离子导通率有明显的提升，这主要是由于多孔材料陶瓷层的孔隙率有明显提升，由此也可以说明实施例1-7的隔膜在电池长循环及倍率性能、低温性能上能够有明显改善。实施例1-7的隔膜的针刺强度测试与对比例1的隔膜的针刺强度测试结果相当，这说明，本申请的隔膜可以满足针刺强度的要求，即同样取得了较好的安全性能。
以上，对本申请的实施方式进行了说明。但是，本申请不限定于上述实施方式。凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (22)

  1. 一种隔膜，其中，所述隔膜包括隔膜基层和设置在隔膜基层的第一表面的陶瓷涂层；其中，所述陶瓷涂层包括陶瓷颗粒；所述陶瓷涂层的表面和/或内部具有微孔，所述陶瓷涂层的孔隙率为40％-80％，所述微孔中，孔径为0.1微米以上的孔的体积占总孔体积的45-90％，孔径为1.0微米以上的孔的体积占总孔体积的40-80％。
  2. 根据权利要求1所述的隔膜，其中，所述微孔中的最大孔的孔径不超过10微米；和/或，
    所述微孔中的最小孔的孔径不小于0.01微米。
  3. 根据权利要求1或2所述的隔膜，其中，所述隔膜的总面密度为9.4-10.0g/m 2。
  4. 根据权利要求1-3任一项所述的隔膜，其中，所述隔膜基层的材料体系选自聚乙烯、聚丙烯、聚对苯二甲酸乙二酯、聚对苯二甲酸丁二酯、聚苯乙烯、聚萘体系聚合物、聚酰亚胺、聚酰胺、芳纶和聚对苯撑苯并二恶唑中的至少一种。
  5. 根据权利要求1-4任一项所述的隔膜，其中，所述隔膜基层的孔隙率为20％-80％。
  6. 根据权利要求1-5任一项所述的隔膜，其中，所述隔膜基层的厚度为5-50μm。
  7. 根据权利要求1所述的隔膜，其中，所述陶瓷颗粒的加入量为陶瓷涂层总质量的80-97wt％。
  8. 根据权利要求1或7所述的隔膜，其中，所述陶瓷涂层还包括助剂，所述助剂包括粘结剂、增稠剂和分散剂。
  9. 根据权利要求8所述的隔膜，其中，所述粘结剂的加入量为陶瓷涂层总质量的1-10wt％；所述增稠剂的加入量为陶瓷涂层总质量的1-10wt％；所述分散剂的加入量为陶瓷涂层总质量的1-5wt％。
  10. 根据权利要求1-9任一项所述的隔膜，其中，所述陶瓷涂层的表层和/或内部存在大量的微孔，微孔的形成是由于在制备陶瓷涂层的浆料中添加热敏聚合物，再通过干燥工艺进行热处理后制备得到 表层和/或内部存在大量微孔的陶瓷涂层；其中，热处理过程中热敏聚合物经熔融后从体系中分离，在陶瓷涂层的表层和/或内部存在大量的微孔。
  11. 根据权利要求1-9任一项所述的隔膜，其中，所述陶瓷涂层通过以下制备方法制得：
    将热敏聚合物加入制备陶瓷涂层的浆料中，再分别经过干燥和热处理得到陶瓷涂层。
  12. 根据权利要求10或11所述的隔膜，其中，所述热敏聚合物选自聚乙烯、聚苯乙烯、聚甲基丙烯酸甲酯、聚丙烯酸-丁二烯-苯乙烯、聚乳酸、聚氯乙烯、聚乙烯丁醛等或其单体改性共聚的聚合物的至少一种。
  13. 根据权利要求10-12任一项所述的隔膜，其中，所述热敏聚合物为热敏聚合物微球，所述热敏聚合物微球的粒径为0.01μm-10μm。
  14. 根据权利要求10-13任一项所述的隔膜，其中，所述热敏聚合物的熔点为60℃-150℃。
  15. 根据权利要求11-14任一项所述的隔膜，其中，所述干燥的温度为40-120℃，所述干燥的时间为20-600s。
  16. 根据权利要求11-15任一项所述的隔膜，其中，所述热处理的温度比热敏聚合物的熔点高0-20℃，所述热处理的时间为2-10min。
  17. 根据权利要求10-16任一项所述的隔膜，其中，制备陶瓷涂层的浆料中，所述热敏聚合物与所述陶瓷颗粒的重量比为(1-60):(99-40)。
  18. 根据权利要求1-17任一项所述的隔膜，其中，所述陶瓷涂层的厚度为1-10μm。
  19. 根据权利要求1-18任一项所述的隔膜，其中，所述陶瓷颗粒的平均粒径为0.01μm-10μm。
  20. 根据权利要求1-19任一项所述的隔膜，其中，所述隔膜还包括设置在陶瓷涂层表面的第一涂胶层；和/或，
    所述隔膜还包括设置在隔膜基层与第一表面相对的第二表面的第二涂胶层。
  21. 根据权利要求20所述的隔膜，其中，所述第一涂胶层和第二涂胶层的厚度相同或不同，选自1-5μm。
  22. 一种锂离子电池，所述锂离子电池包括权利要求1-21任一项所述的隔膜。
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