WO2023245837A1 - 隔离膜、其制备方法及其相关的二次电池和用电装置 - Google Patents

隔离膜、其制备方法及其相关的二次电池和用电装置 Download PDF

Info

Publication number
WO2023245837A1
WO2023245837A1 PCT/CN2022/112582 CN2022112582W WO2023245837A1 WO 2023245837 A1 WO2023245837 A1 WO 2023245837A1 CN 2022112582 W CN2022112582 W CN 2022112582W WO 2023245837 A1 WO2023245837 A1 WO 2023245837A1
Authority
WO
WIPO (PCT)
Prior art keywords
coating
optionally
filler
isolation film
solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2022/112582
Other languages
English (en)
French (fr)
Inventor
徐�明
杨建瑞
魏满想
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Priority to EP22947578.5A priority Critical patent/EP4542754A4/en
Priority to KR1020247039011A priority patent/KR20250007598A/ko
Priority to CN202280018804.7A priority patent/CN116918160A/zh
Priority to JP2024569000A priority patent/JP7850288B2/ja
Publication of WO2023245837A1 publication Critical patent/WO2023245837A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—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
    • 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
    • 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
    • H01M50/426—Fluorocarbon polymers
    • 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
    • H01M50/429—Natural polymers
    • H01M50/4295—Natural cotton, cellulose or wood
    • 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
    • H01M50/494—Tensile strength
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/10—Batteries in stationary systems, e.g. emergency power source in plant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application belongs to the field of battery technology, and specifically relates to an isolation film, its preparation method and related secondary batteries and electrical devices.
  • secondary batteries have been widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace.
  • energy storage power systems such as hydraulic, thermal, wind and solar power stations
  • their safety issues, especially thermal safety issues have received more and more attention.
  • the current methods used to improve the thermal safety performance of secondary batteries are often not conducive to balancing the energy density and capacity of secondary batteries. Therefore, how to make secondary batteries take into account high energy density, high thermal safety performance and long service life is a key challenge in secondary battery design.
  • the purpose of this application is to provide an isolation film, its preparation method and related secondary batteries and electrical devices.
  • the isolation film has the characteristics of excellent heat resistance, good uniformity and good ion conductivity, so that it can be used
  • the secondary battery with this separator film can combine high energy density, high thermal safety performance and long service life.
  • a first aspect of the present application provides an isolation membrane, including a porous substrate and a coating disposed on at least one surface of the porous substrate, wherein the coating includes a three-dimensional skeleton structure and fillers, and the filler contains At least a portion is filled in the three-dimensional skeleton structure, and the zeta potential of the coating is less than 0 mV.
  • the Zeta potential of the coating is tested by the following method: stir and mix 30g of coating material powder with 2000g of deionized water to obtain a dispersion, and test the Zeta potential of the obtained dispersion with a Zeta potentiometer, which is the coating. Zeta potential of the layer.
  • the coating slurry when the Zeta potential of the coating is within a suitable range, the coating slurry has good dispersion, so that the coating slurry can be dried to form a layer with good surface density and thickness uniformity.
  • the coating improves the heat resistance of the isolation film.
  • the coating pores are evenly distributed to ensure good ion conductivity of the coating, thereby improving the rate performance, thermal safety performance and cycle performance of the secondary battery.
  • At least part of the filler is filled in the three-dimensional skeleton structure, which helps the filler and the three-dimensional skeleton structure to form a nesting effect, thereby increasing the heat resistance of the isolation film, reducing the degree of shrinkage of the isolation film when heated, and reducing the positive electrode and
  • the risk of negative electrode short circuit enables the secondary battery to have high thermal safety performance and maintain high bonding strength between the coating and the porous substrate to prevent the filler from falling off during the long-term charging and discharging process of the secondary battery.
  • At least part of the filler is filled in the three-dimensional skeleton structure, so that the filler can also overlap with the three-dimensional skeleton structure, so that the coating has a stable spatial network structure, which can not only increase the ion conduction channel of the isolation membrane and promote The ion transmission can also improve the wetting and retention characteristics of the electrolyte of the isolation membrane, so that the secondary battery using the isolation membrane of the present application can have a long service life. Since the coating of the present application has high heat resistance, a thinner porous substrate can be selected, and the secondary battery using the separator of the present application can also take into account high energy density.
  • the zeta potential of the coating is -50mV to -5mV, optionally -25mV to -5mV. This helps to further improve the uniformity of surface density and thickness of the coating and the uniformity of pores, thereby further improving the ion conductivity of the isolation membrane and the energy density and cycle performance of the secondary battery.
  • the material constituting the three-dimensional skeleton structure includes at least one of organic rods and organic tubes. Materials with appropriate shapes are conducive to better overlapping of the three-dimensional skeleton structure and fillers, so that the coating has a more stable spatial network structure, which can further improve the heat resistance and ion conductivity of the isolation film.
  • the material constituting the three-dimensional skeleton structure includes at least one of nanocellulose, polytetrafluoroethylene nanofibers and polyamide nanofibers.
  • the nanocellulose includes fibers. at least one of cellulose nanofibers, cellulose nanowhiskers and bacterial nanocellulose.
  • the material constituting the three-dimensional skeleton structure includes nanocellulose, and the nanocellulose includes a hydroxyl group and an anionic modifying group.
  • the anionic modifying group includes an amine group. , at least one of a carboxyl group, a sulfonic acid group, a boric acid group and a phosphoric acid group, and more optionally includes at least one of a sulfonic acid group, a boric acid group and a phosphoric acid group.
  • nanocellulose has the above-mentioned specific anionic modification group, it can ensure that the coating slurry has a suitable viscosity, which is more conducive to coating, thereby improving the production efficiency of the isolation film; it also helps the coating to have a suitable viscosity.
  • the Zeta potential can further improve the uniformity of surface density and thickness of the coating and the uniformity of pores, which can further improve the ion conductivity of the isolation membrane and the energy density and cycle performance of the secondary battery.
  • the molar ratio of the anionic modification group to the hydroxyl group is 1:4 to 4:1, optionally 2:3 to 7:3. This can further improve the uniformity of surface density and thickness of the coating and the uniformity of pores, as well as improve the heat resistance, ion conductivity, and electrolyte wetting and retention characteristics of the isolation membrane.
  • the average diameter of the material constituting the three-dimensional skeleton structure is ⁇ 40 nm, optionally ranging from 10 nm to 35 nm. This can further improve the ion conductivity and voltage breakdown resistance of the isolation membrane, and at the same time, it can also help the materials constituting the three-dimensional skeleton structure and the filler to overlap to form an integrated effect, which can further improve the isolation membrane's performance. Heat resistance.
  • the average length of the material constituting the three-dimensional skeleton structure is 100 nm to 600 nm, optionally 200 nm to 400 nm. This can further improve the heat resistance and ion conductivity of the isolation film.
  • the aspect ratio of the material constituting the three-dimensional skeleton structure is 5 to 60, optionally 15 to 30. This can further improve the ion conductivity of the isolation membrane.
  • the filler includes at least one of filler particles with primary particle morphology and filler particles with secondary particle morphology.
  • the filler includes filler with secondary particle morphology.
  • the filler includes both primary particle morphology filler particles and secondary particle morphology filler particles.
  • the average particle size of the primary particle morphology filler particles ranges from 200 nm to 800 nm, optionally from 200 nm to 400 nm.
  • the BET specific surface area of the primary particle morphology filler particles is ⁇ 10m 2 /g, optionally 3m 2 /g to 7m 2 /g.
  • the content of the primary particle morphology filler particles is ⁇ 30wt%, optionally 5wt% to 25wt%, based on the total weight of the coating.
  • the particle size of the primary particle morphology filler particles is larger, which can better play its supporting role in the coating, reduce the shrinkage of the secondary particle morphology filler particles, reduce the amount of binder, thereby improving isolation
  • the heat resistance of the membrane; the larger particle size of the primary particle morphology filler particles helps the coating to have more pore structure and less water content when the dosage is small, which can further improve the performance of the isolation membrane. Ion conductivity and electrolyte wetting and retention properties.
  • the average particle diameter of the filler particles with secondary particle morphology is ⁇ 200 nm, and can optionally be 50 nm to 200 nm.
  • the BET specific surface area of the filler particles with secondary particle morphology is ⁇ 20m 2 /g, optionally 30m 2 /g to 80m 2 /g.
  • the content of the secondary particle morphology filler particles is ⁇ 60wt%, optionally 70wt% to 90wt%, based on the total weight of the coating.
  • Filler particles with secondary particle morphology have the advantages of large specific surface area and good affinity with the three-dimensional skeleton structure, which can better overlap with the three-dimensional skeleton structure, giving the coating a more stable spatial network structure. This can not only increase the ion conduction channel of the isolation membrane, promote ion transmission, but also improve the heat resistance of the isolation membrane to wet and retain the electrolyte. Therefore, the secondary battery using the isolation membrane of the present application can have long-term performance. Long service life and good rate performance.
  • the filler includes both primary particle morphology filler particles and secondary particle morphology filler particles, and the secondary particle morphology filler particles are different from the primary particle morphology.
  • the mass ratio of filler particles is 2:1 to 27:1, optionally 5:1 to 15:1. This helps the coating to have a spatial network structure with higher stability and better uniformity.
  • the filler includes at least one of inorganic particles and organic particles.
  • the inorganic particles include at least one selected from the group consisting of inorganic particles with a dielectric constant of 5 or higher, inorganic particles with the ability to transport active ions, and inorganic particles capable of electrochemical oxidation and reduction.
  • the organic particles include polystyrene, polyethylene, polyimide, melamine resin, phenolic resin, polypropylene, polyester, polyphenylene sulfide, polyaramid, polyamideimide, At least one of polyimide, copolymer of butyl acrylate and ethyl methacrylate, and mixtures thereof.
  • the content of the three-dimensional skeleton structure in the coating is 6 to 35 wt%, optionally 10 to 30 wt%, based on the total weight of the coating. This can ensure that the coating slurry has a suitable viscosity, which is more conducive to coating; in addition, it is also conducive to the integration effect of the three-dimensional skeleton structure and filler overlap, which can make the coating have a more stable spatial network structure.
  • the mass ratio of the three-dimensional skeleton structure to the filler is 1:2 to 1:15.5, optionally 1:5 to 1:10. This helps the coating have a suitable Zeta potential, which can further improve the uniformity of surface density and thickness of the coating and the uniformity of pores, thereby further improving the ion conductivity of the isolation membrane and the energy density of the secondary battery. and cycle performance.
  • the coating further includes a non-granular binder.
  • the non-granular binder includes an aqueous solution binder.
  • the content of the non-granular binder in the coating is ⁇ 2 wt%, based on the total weight of the coating.
  • the three-dimensional skeleton structure and filler in the coating of the present application can be overlapped together so that the coating has a stable spatial network structure, thereby enabling the isolation film to maintain high adhesion while reducing the amount of binder.
  • the thickness of the porous substrate is ⁇ 6 ⁇ m, optionally 3 ⁇ m to 5 ⁇ m. This helps to increase the energy density of secondary batteries.
  • the thickness of the coating is ⁇ 1 ⁇ m, optionally 0.5 ⁇ m to 0.8 ⁇ m. This helps to increase the energy density of secondary batteries.
  • the isolation film further includes an adhesive layer, the adhesive layer is disposed on at least a portion of the surface of the coating, and the adhesive layer includes a granular adhesive.
  • the granular binder includes at least one of acrylic monomer homopolymers or copolymers, acrylic monomer homopolymers or copolymers, and fluorine-containing olefin monomer homopolymers or copolymers.
  • the adhesive layer can not only prevent the coating from peeling off, improve the adhesion between the coating and the porous substrate and improve the safety performance of the secondary battery, but also improve the interface between the isolation film and the electrode, and improve the cycle performance of the secondary battery.
  • the longitudinal thermal shrinkage rate of the isolation film at 150° C. for 1 hour is ⁇ 5%, optionally 0.5% to 3%.
  • the transverse thermal shrinkage rate of the isolation film at 150° C. for 1 hour is ⁇ 5%, and can optionally be 0.5% to 3%.
  • the longitudinal tensile strength of the isolation film is ⁇ 2000kg/cm 2 , optionally 2500kg/cm 2 to 4500kg/cm 2 .
  • the transverse tensile strength of the isolation film is ⁇ 2000kg/cm 2 , optionally 2500kg/cm 2 to 4500kg/cm 2 .
  • the wetted length of the isolation film is ⁇ 30mm, optionally from 30mm to 80mm.
  • the wetting speed of the isolation film is ⁇ 3 mm/s, and may be selected from 3 mm/s to 10 mm/s.
  • the air permeability of the isolation film is ⁇ 300s/100mL, and can be selected from 100s/100mL to 230s/100mL.
  • the performance of the isolation film meets one or more of the above conditions, it is beneficial to improve at least one of the energy density, thermal safety performance and service life of the secondary battery.
  • the second aspect of this application provides a method for preparing the isolation membrane of the first aspect of this application, including the following steps: S1, providing a porous substrate; S2, preparing a coating slurry, which will be used to form the three-dimensional skeleton structure of materials and fillers.
  • the isolation membrane includes a porous substrate and a coating disposed on at least one surface of the porous substrate, the coating includes a three-dimensional skeleton structure and fillers, at least a part of the fillers is filled in the three-dimensional skeleton structure, and the zeta potential of the coating is less than 0 mV.
  • the Zeta potential of the coating is tested by the following method: stir and mix 30g of coating material powder with 2000g of deionized water to obtain a dispersion, and test the Zeta potential of the obtained dispersion with a Zeta potentiometer, which is the coating. Zeta potential of the layer.
  • the pH of the coating slurry is from 5 to 10, optionally from 6 to 9.
  • the static viscosity of the coating slurry is below 1000 mpa.s.
  • the coating slurry is obtained in the following manner: Step 1, prepare a nanocellulose solution, and mix nanocellulose with anionic modification groups with water to prepare the nanocellulose. Solution, wherein the pH of the nanocellulose solution is between 5 and 9, and the Zeta potential is less than 0 mV; Step 2, prepare a filler solution, the pH of the filler solution is ⁇ 7.5, and the Zeta potential is less than 0 mV; Step 3 , mix, and mix the nanocellulose solution and the filler solution according to a predetermined ratio to obtain a coating slurry, wherein the Zeta potential of the coating slurry is below -5mV.
  • the concentration of the nanocellulose solution is 1 to 10 wt%, optionally 2 to 10 wt%.
  • the concentration of the filler solution is 30wt% to 60wt%, optionally 35wt% to 55wt%.
  • the nanocellulose with anionic modification groups is obtained in the following manner: after mixing and reacting the nanocellulose powder with the modification solution, and then washing and removing impurities, the nanocellulose with anionic modification is obtained. group, adjust the pH of the obtained cellulose nanowhiskers with anionic modification groups to neutral, and grind and cut to obtain nanocellulose with anionic modification groups.
  • the modified solution is a sulfuric acid aqueous solution, a boric acid aqueous solution, a phosphoric acid aqueous solution, an acetic acid aqueous solution or a urea organic solvent solution.
  • the filler solution is obtained by mixing the filler, water and a modifier to obtain a filler solution with a pH of ⁇ 7.5 and a Zeta potential of less than 0 mV.
  • the modifier includes selected At least one of self-base, anionic surfactant and nonionic surfactant.
  • the base includes at least one selected from KOH, NaOH, NaHCO 3 , LiOH, NH 4 OH, Mg(OH) 2 and Na 2 CO 3 .
  • the anionic surfactant includes a sulfonate anionic surfactant, a carboxylate anionic surfactant, a sulfate ester salt anionic surfactant, and a phosphate ester salt anionic surfactant.
  • At least one of the surfactants may optionally include alkyl benzene sulfonate, C12-C20 alkyl sulfonate, sodium polyacrylate, ammonium polyacrylate, sodium hydroxyethyl sulfate and C12-C20 alkyl At least one of sodium sulfate.
  • the nonionic surfactant includes at least one selected from the group consisting of fluoroalkyl ethoxy alcohol ethers and fatty alcohol polyoxyethylene ethers.
  • the method further includes the following steps: S4, secondary coating, applying a slurry containing a granular binder on at least a portion of the surface of the coating, after drying Form an adhesive layer.
  • the preparation method of the isolation film of the present application obtains the coating through one-time coating, which greatly simplifies the production process of the isolation film.
  • a third aspect of the present application provides a secondary battery, including the separator film of the first aspect of the present application or a separator film prepared by the method of the second aspect of the present application.
  • a fourth aspect of the present application provides an electrical device, including the secondary battery of the third aspect of the present application.
  • This application provides a coating including a three-dimensional skeleton structure and fillers on the surface of the porous substrate of the isolation membrane, and adjusts the Zeta potential of the coating to less than 0 mV, so that the isolation membrane can achieve both high heat resistance, high uniformity and good ions. conductivity, thus enabling secondary batteries to combine high energy density, high thermal safety performance and long service life.
  • the electrical device of the present application includes the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery.
  • FIG. 1 is a schematic diagram of an embodiment of the secondary battery of the present application.
  • FIG. 2 is an exploded schematic view of the embodiment of the secondary battery of FIG. 1 .
  • FIG. 3 is a schematic diagram of an embodiment of the battery module of the present application.
  • FIG. 4 is a schematic diagram of an embodiment of the battery pack of the present application.
  • FIG. 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of an embodiment of a power consumption device including the secondary battery of the present application as a power source.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • steps (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • a secondary battery includes an electrode assembly and an electrolyte.
  • the electrode assembly includes a positive electrode piece, a negative electrode piece, and an isolation film.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece to prevent short circuit between the positive electrode and the negative electrode. function, and at the same time, active ions can pass freely to form a loop.
  • the isolation film used in commercial secondary batteries is usually a polyolefin porous film, such as a polyethylene porous film, a polypropylene porous film or a polypropylene/polyethylene/polypropylene three-layer composite film, with a melting point between 130°C and 160°C. Therefore, when the thickness of the isolation film is reduced, the heat resistance of the isolation film becomes worse, and an obvious thermal shrinkage effect will occur when heated, causing direct contact between the positive and negative electrodes inside the battery, resulting in an internal short circuit, thereby increasing the number of secondary batteries. security risks.
  • the current measures are mainly to coat a heat-resistant inorganic ceramic layer on the polyolefin porous membrane, which can increase the mechanical strength of the isolation membrane, reduce the shrinkage of the isolation membrane when heated, and reduce the battery life. Risk of internal short circuit between positive and negative terminals.
  • the particle size of commercially available inorganic ceramic particles is larger, which will increase the overall thickness of the isolation film, resulting in the inability to balance the energy density of secondary batteries, especially in the field of power batteries, which is not conducive to improving the cruising range; in addition, due to the The particle size of inorganic ceramic particles is larger, so the number of layers accumulated on the polyolefin porous membrane is smaller (usually ⁇ 5 layers), which results in limited improvement in the heat resistance of the isolation membrane. Nanonization of inorganic ceramic particles can reduce the coating thickness and alleviate the adverse impact on the energy density of secondary batteries.
  • the coating formed by nanonized inorganic ceramic particles has low porosity and is easy to block the polyolefin porous membrane, resulting in the overall deterioration of the isolation membrane.
  • the porosity decreases, the ionic resistance increases, and the ion transmission is blocked, which in turn leads to the deterioration of the capacity and kinetic performance of the secondary battery.
  • a large amount of binder is required to ensure the adhesion between particles, but the amount of binder is large. Blocking problems are prone to occur, which is detrimental to the rate performance of the secondary battery. For example, dendrites are easily formed on the surface of the negative electrode, which is also detrimental to the capacity, energy density, and service life of the secondary battery.
  • the polyolefin porous membrane is a hydrophobic material, while the inorganic ceramic particles are hydrophilic materials. Therefore, when the inorganic ceramic slurry is coated on the surface of the polyolefin porous membrane, there will be problems such as coating leakage and poor uniformity. Therefore, It affects the uniformity of the isolation film, which in turn affects the capacity and dynamic performance of the secondary battery.
  • the inventor of the present application surprisingly discovered during the research process that by arranging a coating including a three-dimensional skeleton structure and fillers on the surface of the porous substrate of the isolation membrane, and adjusting the Zeta potential of the coating within an appropriate range, the isolation membrane can be made to have both high and high performance. Heat resistance, high uniformity and good ion conductivity enable secondary batteries to combine high energy density, high thermal safety performance and long service life.
  • the first aspect of the embodiment of the present application provides an isolation membrane, including a porous substrate and a coating disposed on at least one surface of the porous substrate, wherein the coating includes a three-dimensional skeleton structure and a filler. , at least a part of the filler is filled in the three-dimensional skeleton structure, and the Zeta potential of the coating is less than 0 mV.
  • the Zeta potential of the coating is tested by the following method: stir and mix 30g of coating material powder with 2000g of deionized water to obtain a dispersion, and test the Zeta potential of the obtained dispersion with a Zeta potentiometer, which is the coating. Zeta potential of the layer.
  • Coating material powder can be obtained by scraping (for example, blade scraping) sampling, and the scraping depth does not exceed the boundary area between the coating and the porous substrate.
  • the dispersion can be obtained by fully stirring with a stirrer with a toothed disc.
  • the stirring time can be from 1 hour to 3 hours, and the stirring speed can be from 1500r/min to 3000r/min.
  • the Zeta potentiometer can be Malvern's Zetasizer series of nanoparticle size potentiometers, such as the Zetasizer Advance nanoparticle size potentiometer, and the sample cell can be Malvern's DTS1070 Zeta potential capillary sample cell.
  • the obtained dispersion can be placed in Malvern's DTS1070 Zeta potential capillary sample cell for testing, and then the Zeta potential of the obtained dispersion can be tested through ZS Xplorer software.
  • ZS Xplorer software For testing standards, please refer to GB/T 32671.2-2019 and ISO 13099-2-2012.
  • multiple parallel samples can be taken for testing and then the average value can be taken.
  • the isolation membrane can be made to have high heat resistance. properties, high uniformity and good ion conductivity, which enables secondary batteries to take into account high energy density, high thermal safety performance and long service life.
  • the coating slurry has good dispersion. Therefore, after the coating slurry is dried, a coating with good surface density and thickness uniformity can be formed, improving the performance of the isolation film. Heat resistance and uniform distribution of coating pores can ensure good ionic conductivity of the coating, thereby improving the rate performance, thermal safety performance and cycle performance of secondary batteries.
  • At least part of the filler is filled in the three-dimensional skeleton structure, which helps the filler and the three-dimensional skeleton structure to form a nesting effect, thereby increasing the heat resistance of the isolation film and reducing the degree of shrinkage of the isolation film when heated. It reduces the risk of short circuit of the positive and negative electrodes, enables the secondary battery to have high thermal safety performance, and maintains high bonding strength between the coating and the porous substrate to prevent the filler from falling off during the long-term charging and discharging process of the secondary battery.
  • the filler is filled in the three-dimensional skeleton structure, so that the filler can also overlap with the three-dimensional skeleton structure, so that the coating has a stable spatial network structure, which can not only increase the ion conduction of the isolation membrane channel, promote ion transmission, and improve the infiltration and retention characteristics of the isolation membrane to the electrolyte, so that the secondary battery using the isolation membrane of the present application can have a long service life.
  • the coating of the present application has high heat resistance, a thinner porous substrate can be selected, and the secondary battery using the separator of the present application can also take into account high energy density.
  • the zeta potential of the coating may be -50mV to -5mV, optionally -25mV to -5mV, more optionally -15mV to -6mV. This helps to further improve the uniformity of surface density and thickness of the coating and the uniformity of pores, thereby further improving the ion conductivity of the isolation membrane and the energy density and cycle performance of the secondary battery. And it can effectively avoid the following situations: when the Zeta potential of the coating is too low, the viscosity of the coating slurry may be too high and the fluidity is too poor, which may affect the coating of the coating slurry and thus affect the surface density and surface density of the coating. Uniformity of thickness and uniformity of pores.
  • the material constituting the three-dimensional skeleton structure may include at least one of organic rods and organic tubes. Materials with appropriate shapes are conducive to better overlapping of the three-dimensional skeleton structure and fillers, so that the coating has a more stable spatial network structure, which can further improve the heat resistance and ion conductivity of the isolation film.
  • the material constituting the three-dimensional skeleton structure may include at least one of nanocellulose, polytetrafluoroethylene nanofibers, and polyamide nanofibers.
  • the material constituting the three-dimensional skeleton structure may include nanocellulose.
  • the nanocellulose includes cellulose nanofibrils (Cellulose nanofibrils, CNF, also known as nanofibrillar cellulose or microfibrillated cellulose), cellulose nanowhiskers (Cellulose nanocrystals, CNC, also known as At least one of cellulose nanocrystals, nanocrystalline cellulose) and bacterial nanocellulose (Bacterial nanocellulose, BNC, also known as bacterial cellulose or microbial cellulose).
  • the nanocellulose includes cellulose nanowhiskers, which have the advantage of high crystallinity, thereby better improving the heat resistance of the isolation film.
  • Nanocellulose refers to the general name of cellulose with any dimension in the nanoscale (for example, within 100 nm), which has the characteristics of both cellulose and nanoparticles.
  • Nanocellulose can be a polymer nanomaterial extracted from wood, cotton, etc. in nature through one or more means of chemistry, physics, biology, etc. It has wide sources, low cost, biodegradability, and high modulus. , high specific surface area, etc., so it is an excellent substitute for traditional petrochemical resources and can effectively alleviate problems such as environmental pollution and petrochemical resource shortages.
  • the nanocellulose may include a hydroxyl group and an anionic modifying group.
  • the anionic modifying group includes at least one of an amine group, a carboxyl group, a sulfonic acid group, a boric acid group and a phosphate group.
  • the inventor found that when nanocellulose has the above-mentioned specific anionic modification group, it can ensure that the coating slurry has a suitable viscosity, which is more conducive to coating, thereby improving the production efficiency of the isolation film; at the same time It also helps the coating to have a suitable Zeta potential, which can further improve the uniformity of surface density and thickness of the coating and the uniformity of pores, which can further improve the ion conductivity of the isolation membrane and the energy density and energy density of the secondary battery. Cycle performance.
  • nanocellulose has the above-mentioned specific anionic modification groups, it can also effectively improve the heat resistance of the isolation film and the bonding strength between the coating and the porous substrate.
  • nanocellulose has the above-mentioned specific anionic modification group
  • the molar ratio of the anionic modifying group to the hydroxyl group may be 1:4 to 4:1, optionally 2:3 to 7:3.
  • the molar ratio of the anionic modification group to the hydroxyl group is within an appropriate range, the uniformity of surface density and thickness of the coating as well as the uniformity of pores can be further improved, as well as the heat resistance, ion conductivity and ion conductivity of the isolation membrane can be improved. Wetting and retention properties for electrolyte. And it can effectively avoid the following situation: when the molar ratio of anionic modification group to hydroxyl group is too small, the anionic modification group may further improve the uniformity of surface density and thickness of the coating and the uniformity of pores.
  • the electrolyte infiltration and retention properties of the isolation membrane may become poor, which may affect the cycle performance and safety performance of the secondary battery, and may also lead to isolation
  • the heat resistance of the film decreases, which may also affect the thermal safety performance of the secondary battery.
  • the types of anionic modifying groups in nanocellulose can be determined using infrared spectroscopy.
  • the infrared spectrum of the material can be tested to determine the characteristic peaks it contains, thereby determining the type of anionic modification group.
  • the materials can be analyzed by infrared spectroscopy using instruments and methods known in the art, such as using an infrared spectrometer (such as the IS10 Fourier transform infrared spectrometer of the American Nicoreet Company), according to GB/T 6040-2019 Infrared General principles of spectral analysis methods were tested.
  • the average diameter of the material constituting the three-dimensional skeleton structure may be ⁇ 40 nm, optionally 10 nm to 35 nm.
  • the ion conductivity and voltage breakdown resistance characteristics of the isolation membrane can be further improved, and it also helps to match the materials constituting the three-dimensional skeleton structure with fillers.
  • the joints form an integrated effect, which can further improve the heat resistance of the isolation film.
  • the average length of the material constituting the three-dimensional skeleton structure may be 100 nm to 600 nm, optionally 200 nm to 400 nm.
  • the average length of the materials constituting the three-dimensional skeleton structure is within an appropriate range, the heat resistance and ion conductivity of the isolation film can be further improved.
  • the average length of the material constituting the three-dimensional skeleton structure is too short, the overlapping effect with the filler is poor, the heat resistance of the coating may become worse, and during the drying process of the coating, Part of the three-dimensional skeleton structure is easy to collapse due to the lack of support from the filler, which can easily block the micropores of the porous substrate, hinder ion transmission and water discharge, which may also affect the cycle performance and rate performance of the secondary battery; when forming a three-dimensional When the average length of the skeleton structure material is too long, the viscosity of the coating slurry will be high and the dispersibility will be poor. Therefore, the surface density and thickness uniformity of the coating formed after the coating slurry is dried, as well as the uniformity of the pores, may become poor.
  • the aspect ratio of the material constituting the three-dimensional skeleton structure may be 5 to 60, optionally 15 to 30.
  • the ion conductivity of the isolation membrane can be further improved.
  • the aspect ratio of the material constituting the three-dimensional skeleton structure is too small, the overlap effect with the filler is poor, the heat resistance of the coating may become worse, and during the drying process of the coating, Part of the three-dimensional skeleton structure is easy to collapse due to the lack of support from the filler, which can also easily block the micropores of the porous substrate, hindering ion transmission and water discharge, which may affect the cycle performance and rate performance of the secondary battery; when forming a three-dimensional skeleton When the aspect ratio of the structural material is too large, the pores of the three-dimensional skeleton structure formed by it are smaller, which may lead to poor ion conductivity of the isolation membrane.
  • the average length and average diameter of the materials constituting the three-dimensional skeleton structure can be determined by the following method: cut out a 3.6mm ⁇ 3.6mm sample from any area of the isolation film, and measure the sample using a scanning electron microscope (such as ZEISS Sigma 300)
  • a scanning electron microscope such as ZEISS Sigma 300
  • For the microstructure of the intermediate coating select the high vacuum mode, the operating voltage is 3kV, and the magnification is 30,000 times to obtain the SEM image; based on the obtained SEM image, select multiple (for example, more than 5) test areas for length measurement.
  • the size of each test area is 0.5 ⁇ m ⁇ 0.5 ⁇ m, and then the average length of each test area is taken as the average length of the material constituting the three-dimensional skeleton structure; according to the obtained SEM image, use Nano Measurer particle size distribution statistics Software, select multiple (for example, more than 5) test areas for diameter statistics.
  • the size of each test area is 0.5 ⁇ m ⁇ 0.5 ⁇ m. Then, take the average value of the diameters obtained in each test area as the material constituting the three-dimensional skeleton structure. The average diameter.
  • the content of the three-dimensional skeleton structure in the coating may be 6 to 35 wt%, optionally 10 to 30 wt%, based on the total weight of the coating.
  • the content of the three-dimensional skeleton structure is within a suitable range, it can ensure that the coating slurry has a suitable viscosity, which is more conducive to coating; in addition, it is also conducive to the overlapping of the three-dimensional skeleton structure and the filler to form an integrated effect, thus enabling
  • the coating has a more stable spatial network structure, which can further improve the ion conductivity of the isolation membrane, the wetting and retention characteristics of the electrolyte, and the ability to withstand voltage breakdown.
  • the volume of the entire battery will increase.
  • the negative active material is embedded
  • the volume increase after active ions is higher.
  • the isolation film also needs to have good resistance to external extrusion.
  • At least part of the filler is filled in the three-dimensional skeleton structure, which helps the coating to have a stable spatial network structure, thereby improving the ion conductivity and heat resistance of the isolation membrane; in addition, it can also improve the tensile strength of the isolation membrane , puncture resistance and external extrusion resistance.
  • the filler may include at least one of filler particles with a primary particle morphology and filler particles with a secondary particle morphology.
  • the filler may include filler particles with a secondary particle morphology,
  • the filler includes both primary particle morphology filler particles and secondary particle morphology filler particles.
  • Filler particles with secondary particle morphology have the advantages of large specific surface area and good affinity with the three-dimensional skeleton structure, which can better overlap with the three-dimensional skeleton structure, giving the coating a more stable spatial network structure. This can not only increase the ion conduction channel of the isolation membrane and promote ion transmission, but also improve the heat resistance of the isolation membrane and the infiltration and retention characteristics of the electrolyte.
  • the secondary battery using the isolation membrane of the present application can have Long service life and good rate performance.
  • the particle size of the primary particle morphology filler particles is larger, which can better play its supporting role in the coating, reduce the shrinkage of the secondary particle morphology filler particles, reduce the amount of binder, thereby improving isolation
  • the heat resistance of the membrane; the larger particle size of the primary particle morphology filler particles helps the coating to have more pore structure and less water content when the dosage is small, which can further improve the performance of the isolation membrane. Ion conductivity and electrolyte wetting and retention properties.
  • the filler includes both primary particle morphology filler particles and secondary particle morphology filler particles, and the difference between the secondary particle morphology filler particles and the primary particle morphology filler particles is The mass ratio is 2:1 to 27:1, optionally 5:1 to 15:1. This helps the coating to have a spatial network structure with higher stability and better uniformity.
  • the average particle diameter of the primary particle morphology filler particles may be 200 nm to 800 nm, optionally 200 nm to 400 nm.
  • the supporting role of the primary particle morphology of the filler particles can be better exerted, so that the coating maintains a stable pore structure during long-term charge and discharge processes, which is beneficial to ion transmission.
  • the BET specific surface area of the primary particle morphology filler particles may be ⁇ 10 m 2 /g, optionally 3 m 2 /g to 7 m 2 /g.
  • the supporting role of the primary particle morphology of the filler particles can be better exerted, so that the coating maintains a stable pore structure during long-term charge and discharge processes, which is beneficial to ion transmission.
  • the content of the primary particle morphology filler particles may be ⁇ 30 wt%, optionally 5 to 25 wt%, based on the total weight of the coating.
  • the supporting role of the primary particle morphology of the filler particles can be better exerted, so that the coating maintains a stable pore structure during long-term charge and discharge processes, which is beneficial to ion transmission.
  • the average particle size of the filler particles with secondary particle morphology may be ⁇ 200 nm, optionally 50 nm to 200 nm. This can make the filler particles with secondary particle morphology have a higher specific surface area, thereby increasing the affinity between the filler and the three-dimensional skeleton structure, so that the filler and the three-dimensional skeleton structure can be better overlapped together, thus
  • the coating can have a more stable spatial network structure, and the isolation film has better heat resistance, ion conductivity, and electrolyte infiltration and retention properties.
  • the BET specific surface area of the filler particles with secondary particle morphology may be ⁇ 20 m 2 /g, optionally from 30 m 2 /g to 80 m 2 /g.
  • the affinity between the filler and the three-dimensional skeleton structure is better, so that the coating can have a more stable spatial network structure, and the isolation film has better heat resistance, ion conductivity, and electrolyte infiltration and Maintain characteristics.
  • the content of the secondary particle morphology filler particles may be ⁇ 60 wt%, optionally 70 wt% to 90 wt%, based on the total weight of the coating. This can ensure that the coating slurry has an appropriate viscosity, which is more conducive to coating; in addition, it also helps the filler and the three-dimensional skeleton structure to better overlap together, so that the coating has a more stable spatial network structure, thereby further Improve the tensile strength, puncture resistance and external extrusion resistance of the isolation film.
  • the filler includes at least one of inorganic particles and organic particles.
  • the inorganic particles may include at least one selected from inorganic particles having a dielectric constant of 5 or higher, inorganic particles having the ability to transport active ions, and inorganic particles capable of electrochemical oxidation and reduction.
  • the inorganic particles having a dielectric constant of 5 or higher may include selected from the group consisting of boehmite ( ⁇ -AlOOH), aluminum oxide (Al 2 O 3 ), barium sulfate (BaSO 4 ), magnesium oxide ( MgO), magnesium hydroxide (Mg(OH) 2 ), silicon oxide compound SiO x (0 ⁇ x ⁇ 2), tin dioxide (SnO 2 ), titanium oxide (TiO 2 ), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), nickel oxide (NiO), hafnium dioxide (HfO 2 ), cerium oxide (CeO 2 ), zirconium titanate (ZrTiO 3 ), titanium Barium acid (BaTiO 3 ), magnesium fluoride (MgF 2 ), Pb(Zr,Ti)O 3 (abbreviated as PZT), Pb 1-m La m Z
  • the inorganic particles with the ability to transport active ions may include lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate ( LixTi y (PO 4 ) 3 , 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO 4 ) 3 , 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 3), (LiAlTiP) x O y glass (0 ⁇ x ⁇ 4, 0 ⁇ y ⁇ 13), lithium lanthanum titanate (Li x Lay TiO 3 , 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 3), lithium germanium thiophosphate (Li x Ge y P z S w , 0 ⁇ x ⁇ 4, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 0 ⁇ w ⁇ 5), lithium nitride (Li x N y , 0 ⁇ x ⁇ 4, 0 ⁇ y ⁇ 2)
  • the inorganic particles capable of electrochemical oxidation and reduction may include lithium-containing transition metal oxides, olivine-structured lithium-containing phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium titanium. at least one of the compounds.
  • the organic particles may include polystyrene, polyethylene, polyimide, melamine resin, phenolic resin, polypropylene, polyester (e.g., polyethylene terephthalate, polynaphthalate). Ethylene glycol, polybutylene terephthalate), polyphenylene sulfide, polyaramid, polyamideimide, polyimide, copolymers of butyl acrylate and ethyl methacrylate and their mixtures of at least one.
  • the mass ratio of the three-dimensional skeleton structure to the filler may be 1:2 to 1:15.5, optionally 1:5 to 1:10. This helps the coating have a suitable Zeta potential, which can further improve the uniformity of surface density and thickness of the coating and the uniformity of pores, thereby further improving the ion conductivity of the isolation membrane and the energy density of the secondary battery. and cycle performance.
  • the coating may also include a non-granular binder.
  • a non-granular binder There is no particular limitation on the type of non-granular binder in this application, and any well-known material with good adhesiveness can be selected.
  • the non-granular binder includes an aqueous solution binder, which has the advantages of good thermodynamic stability and environmental protection, thereby facilitating the preparation and coating of the coating slurry.
  • the aqueous solution-type binder may include aqueous solution-type acrylic resin (for example, acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer or copolymer with other comonomers), polyvinyl alcohol (PVA), At least one of isobutylene-maleic anhydride copolymer and polyacrylamide.
  • aqueous solution-type acrylic resin for example, acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer or copolymer with other comonomers
  • PVA polyvinyl alcohol
  • At least one of isobutylene-maleic anhydride copolymer and polyacrylamide At least one of isobutylene-maleic anhydride copolymer and polyacrylamide.
  • the content of the non-granular binder in the coating is ⁇ 2 wt%, based on the total weight of the coating.
  • the three-dimensional skeleton structure and filler in the coating of the present application can be overlapped together so that the coating has a stable spatial network structure, thereby enabling the isolation film to maintain high adhesion while reducing the amount of binder.
  • the thickness of the coating may be ⁇ 1 ⁇ m, optionally 0.5 ⁇ m to 0.8 ⁇ m. This helps to increase the energy density of secondary batteries.
  • the thickness of the coating refers to the thickness of the coating on one side of the porous substrate.
  • the thickness of the porous substrate may be ⁇ 6 ⁇ m, optionally 3 ⁇ m to 5 ⁇ m.
  • the coating of the present application can significantly improve the heat resistance of the isolation film, thereby enabling the use of thinner porous substrates, thereby helping to increase the energy density of secondary batteries.
  • the porous substrate can include a porous polyolefin-based resin film (such as polyolefin-based resin film). At least one of ethylene, polypropylene, polyvinylidene fluoride), at least one of porous glass fiber and porous non-woven fabric.
  • the porous substrate may be a single-layer film or a multi-layer composite film. When the porous substrate is a multi-layer composite film, the materials of each layer may be the same or different.
  • the isolation film may further include an adhesive layer disposed on at least a portion of the surface of the coating, the adhesive layer including a granular adhesive.
  • the adhesive layer can not only prevent the coating from peeling off, improve the adhesion between the coating and the porous substrate and improve the safety performance of the secondary battery, but also improve the interface between the isolation film and the electrode, and improve the cycle performance of the secondary battery.
  • the granular binder includes at least one of acrylic monomer homopolymers or copolymers, acrylic monomer homopolymers or copolymers, and fluorine-containing olefin monomer homopolymers or copolymers.
  • the comonomers include, but are not limited to, at least one of the following: acrylate monomers, acrylic acid monomers, olefin monomers, halogen-containing olefin monomers, fluoroether monomers, etc.
  • the particulate binder includes a vinylidene fluoride-based polymer, such as a homopolymer of vinylidene fluoride monomer (VDF) and/or a copolymer of vinylidene fluoride monomer and comonomer.
  • VDF vinylidene fluoride monomer
  • the comonomer may be at least one of olefin monomers, fluorine-containing olefin monomers, chlorine-containing olefin monomers, acrylate monomers, acrylic acid monomers, and fluoroether monomers.
  • the comonomer may include at least one of the following: trifluoroethylene (VF3), chlorotrifluoroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoroethylene Propylene (HFP), perfluoro (alkyl vinyl) ether (such as perfluoro (methyl vinyl) ether PMVE, perfluoro (ethyl vinyl) ether PEVE, perfluoro (propyl vinyl) ether PPVE), Perfluoro(1,3-dioxole) and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD).
  • VF3 trifluoroethylene
  • CTFE chlorotrifluoroethylene
  • TFE tetrafluoroethylene
  • HFP hexafluoroethylene Propylene
  • perfluoro (alkyl vinyl) ether such as perfluoro (methyl vinyl) ether PMVE, perfluoro (
  • the longitudinal thermal shrinkage rate of the isolation film at 150° C. for 1 hour is ⁇ 5%, optionally 0.5% to 3%.
  • the transverse thermal shrinkage rate of the isolation film at 150° C. for 1 hour is ⁇ 5%, optionally 0.5% to 3%.
  • the isolation film of the present application has low thermal shrinkage in both transverse and longitudinal directions at a high temperature of 150°C, thereby improving the safety performance of secondary batteries.
  • the longitudinal tensile strength of the isolation film is ⁇ 2000kg/cm 2 , optionally 2500kg/cm 2 to 4500kg/cm 2 .
  • the transverse tensile strength of the isolation film is ⁇ 2000kg/cm 2 , optionally 2500kg/cm 2 to 4500kg/cm 2 .
  • the isolation film of the present application has high tensile strength in both the transverse and longitudinal directions. Therefore, when the secondary battery expands, the isolation film is less likely to be damaged, thereby improving the safety performance of the secondary battery.
  • the wetted length of the isolation film is ⁇ 30mm, optionally 30mm to 80mm.
  • the wetting speed of the isolation film is ⁇ 3 mm/s, optionally 3 mm/s to 10 mm/s.
  • the isolation membrane of the present application has good wetting and retention characteristics for the electrolyte, thereby improving the ion conductivity of the isolation membrane and the capacity performance characteristics of the secondary battery.
  • the air permeability of the isolation film is ⁇ 300s/100mL, optionally between 100s/100mL and 230s/100mL.
  • the isolation film of the present application has good air permeability, thereby improving ion conductivity and secondary battery capacity performance characteristics.
  • the average particle size of a material is a meaning known in the art, and can be measured using instruments and methods known in the art.
  • a scanning electron microscope, a transmission electron microscope, or a particle size distribution instrument can be used to measure the material or isolation film to obtain a picture. Randomly select multiple (for example, more than 10) test particles from the picture, and calculate the average of the shortest diagonal length of the particles. value as the average particle size.
  • the specific surface area of a material has a well-known meaning in the art, and can be measured using instruments and methods known in the art.
  • the nitrogen adsorption specific surface area analysis test can be performed by the Tri-Star 3020 specific surface area pore size analysis tester of the American Micromeritics Company.
  • thermal shrinkage rate, tensile strength and air permeability of the isolation film all have meanings known in the art, and can be measured using methods known in the art. For example, you can refer to the standard GB/T 36363-2018 for testing.
  • the wetting length and wetting speed of the isolation film have well-known meanings in the art, and can be measured using methods known in the art.
  • An exemplary test method is as follows: Cut the isolation film into a sample with a width of 5mm and a length of 100mm, fix both ends of the sample and place it horizontally; drop 0.5mg of electrolyte in the center of the sample for the specified time (1min in this application) Finally, take pictures and measure the length of electrolyte diffusion, thereby obtaining the wetting length and wetting speed of the isolation film.
  • multiple (for example, 5 to 10) samples can be taken for testing, and the test results are obtained by calculating the average value.
  • the electrolyte can be prepared as follows: mix ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) at a mass ratio of 30:50:20 to obtain an organic solvent. 6 was dissolved in the above organic solvent to prepare an electrolyte solution with a concentration of 1 mol/L.
  • the coating parameters (such as thickness, etc.) of the above-mentioned isolation membrane are the coating parameters of one side of the porous substrate.
  • the coating is disposed on both sides of the porous substrate, if the coating parameters on either side meet the requirements of this application, it is deemed to fall within the protection scope of this application.
  • the second aspect of the embodiment of the present application provides a method for preparing the isolation membrane of the first aspect of the embodiment of the present application, including the following steps: S1, providing a porous substrate; S2, preparing a coating slurry, which will be used to form a three-dimensional skeleton structure The materials and fillers are mixed in a solvent according to a predetermined ratio to prepare a coating slurry; S3, coating, apply the coating slurry on at least one surface of the porous substrate to form a coating and dry it , obtain an isolation film, wherein the isolation film includes a porous substrate and a coating disposed on at least one surface of the porous substrate, the coating including a three-dimensional skeleton structure and fillers, at least a part of the fillers Filled in the three-dimensional skeleton structure, and the zeta potential of the coating is less than 0 mV.
  • the solvent in S2, may be water, such as deionized water.
  • the slurry may also include other components, for example, it may also include dispersants, wetting agents, binders, etc.
  • the material constituting the three-dimensional skeleton structure includes nanocellulose, the nanocellulose includes hydroxyl groups and anionic modification groups, and the anionic modification groups include amine groups, carboxyl groups, At least one of a sulfonic acid group, a boric acid group and a phosphoric acid group optionally includes at least one of a sulfonic acid group, a boric acid group and a phosphoric acid group.
  • the nanocellulose is cellulose nanocrystals (CNC, also known as cellulose nanocrystals, nanocrystalline cellulose).
  • the coating slurry can be obtained in the following manner: Step 1, prepare a nanocellulose solution, mix nanocellulose with anionic modification groups and water to prepare the nanocellulose solution. Cellulose solution, wherein the pH of the nanocellulose solution is between 5 and 9, and the Zeta potential is less than 0 mV; step 2, prepare a filler solution, the pH of the filler solution is ⁇ 7.5, and the Zeta potential is less than 0 mV; Step 3: Mix the nanocellulose solution and the filler solution according to a predetermined ratio to obtain a coating slurry, wherein the Zeta potential of the coating slurry is below -5mV.
  • the nanocellulose with anionic modification groups can be obtained in the following manner: after mixing and reacting the nanocellulose powder with the modified solution, the nanocellulose powder is washed and removed to obtain impurities.
  • the pH of the obtained cellulose nanowhiskers with anionic modified groups is adjusted to neutral (for example, the pH is between 6.5 and 7.5), and ground and cut. Nanocellulose with anionic modifying groups was obtained.
  • the whiteness of the nanocellulose powder may be ⁇ 80%.
  • the cellulose powder can be obtained commercially, or by chemical methods (such as acid hydrolysis, alkali treatment, Tempo catalytic oxidation), biological methods (such as enzyme treatment), mechanical methods (such as ultrafine grinding, ultrasonic crushing, High pressure homogenization) and so on.
  • the fiber raw materials used to prepare the above-mentioned cellulose powder with a whiteness of ⁇ 80% may include plant fibers, such as cotton fiber (such as cotton fiber, kapok fiber), hemp fiber (such as sisal fiber, ramie fiber, jute fiber, flax fiber, Hemp fiber, abaca fiber, etc.), at least one of brown fiber, wood fiber, bamboo fiber, and grass fiber.
  • the cellulose powder can also be prepared in the following manner: after the fiber raw material is opened and slag removed, it is treated with an alkali solution (such as NaOH aqueous solution, the concentration of which can be 4wt% to 20wt%, optionally 5wt% to 15wt%) steaming, and then sequentially undergo water washing to remove impurities (for example, the number of washings is 3 to 6 times), bleaching (for example, sodium hypochlorite and/or hydrogen peroxide can be used), pickling to remove impurities, water washing to remove impurities, and water displacement , airflow drying to obtain cellulose powder.
  • an alkali solution such as NaOH aqueous solution, the concentration of which can be 4wt% to 20wt%, optionally 5wt% to 15wt
  • water washing for example, the number of washings is 3 to 6 times
  • bleaching for example, sodium hypochlorite and/or hydrogen peroxide can be used
  • pickling for example, sodium hypochlorite and/
  • the modification solution may be an acid solution (such as sulfuric acid aqueous solution, boric acid aqueous solution, phosphoric acid aqueous solution, acetic acid aqueous solution) or an alkali solution (such as urea organic solvent solution).
  • the modified solution is an acid solution.
  • the acid solution may have a concentration of 5 to 80 wt%.
  • the concentration of the acid solution can be 40 wt% to 80 wt%, whereby cellulose powder with sulfonic acid groups can be obtained.
  • a boric acid aqueous solution the concentration of the acid solution can be 5 wt% to 10 wt%, whereby cellulose powder with boric acid groups can be obtained.
  • a phosphoric acid aqueous solution the concentration of the acid solution can be 45 wt% to 75 wt%, whereby cellulose powder with phosphate groups can be obtained.
  • the concentration of the acid solution can be 40 wt% to 80 wt%, whereby cellulose powder with carboxylic acid groups can be obtained.
  • the urea organic solvent solution is a urea xylene solution, whereby cellulose powder with amine groups can be obtained.
  • the mass ratio of the cellulose powder to the modified solution may be 1:2.5 to 1:50, optionally 1:5 to 1:30.
  • the mass ratio of the cellulose powder to the acid solution can be 1:5 to 1:30.
  • the mass ratio of the cellulose powder to the acid solution can be 1:20 to 1:50.
  • the modified solution is a phosphoric acid aqueous solution
  • the mass ratio of the cellulose powder to the acid solution can be 1:5 to 1:30.
  • an acetic acid aqueous solution is selected as the modification solution
  • the mass ratio of the cellulose powder to the acid solution may be 1:5 to 1:30.
  • a urea organic solvent solution is selected as the modification solution, the mass ratio of the cellulose powder to the urea organic solvent solution may be 1:4 to 1:40.
  • the reaction when the modified solution is an acid solution, the reaction can be performed at a temperature no higher than 80°C, optionally at a temperature of 30°C to 60°C, and the cellulose
  • the reaction time between the powder and the modified solution can be 0.5h to 4h, optionally 1h to 3h.
  • the reaction when the modified solution is an alkaline solution, the reaction can be carried out at a temperature of 100°C to 145°C, and the reaction time between the cellulose powder and the modified solution can be 1 hour to 145°C. 5h.
  • a grinder can be used for grinding, and a high-pressure homogenizer can be used for cutting.
  • Nanocellulose with different average diameters and/or different average lengths can be obtained by adjusting the grinding parameters of the grinder (such as the number of grinding times, grinding time, etc.) and the cutting parameters of the high-pressure homogenizer.
  • the filler solution in step 2, can be obtained by mixing the filler, water and a modifier to obtain a filler solution with a pH of ⁇ 7.5 and a Zeta potential of less than 0 mV.
  • the agent includes at least one selected from alkali, anionic surfactant and nonionic surfactant.
  • the base includes at least one selected from KOH, NaOH, NaHCO 3 , LiOH, NH 4 OH, Mg(OH) 2 and Na 2 CO 3 .
  • the anionic surfactant includes an anionic surfactant selected from the group consisting of sulfonate type anionic surfactants, carboxylate type anionic surfactants, sulfate ester salt type anionic surfactants and phosphate ester salt type anionic surfactants. At least one, further optionally including alkyl benzene sulfonate (such as sodium butyl naphthalene sulfonate), C12-C20 alkyl sulfonate, sodium polyacrylate, ammonium polyacrylate, sodium hydroxyethyl sulfate and At least one of C12-C20 alkyl sodium sulfates.
  • alkyl benzene sulfonate such as sodium butyl naphthalene sulfonate
  • C12-C20 alkyl sulfonate sodium polyacrylate
  • ammonium polyacrylate sodium hydroxyethyl sulfate
  • the nonionic surfactant includes at least one selected from the group consisting of fluoroalkyl ethoxy alcohol ethers and fatty alcohol polyoxyethylene ethers.
  • the concentration of the nanocellulose solution may be 1 to 10 wt%, optionally 2 to 10 wt%.
  • the concentration of the filler solution may be 30 wt% to 60 wt%, optionally 35 wt% to 55 wt%.
  • the pH of the coating slurry may be from 5 to 10, optionally from 6 to 9.
  • the static viscosity of the coating slurry may be below 1000 mpa.s.
  • the coating uses a coater.
  • This application has no special restrictions on the model of the coating machine.
  • a commercially available coating machine can be used.
  • the coater includes a gravure roller; the gravure roller is used to transfer the slurry onto the porous substrate.
  • the coating method may adopt transfer coating, spin spray coating, dip coating, etc.
  • the method further includes the following steps: S4, secondary coating, applying a slurry containing a granular binder on at least part of the surface of the coating, and forming a bond after drying layer.
  • the preparation method of the isolation film of the present application obtains the coating through one-time coating, which greatly simplifies the production process of the isolation film.
  • isolation film of the present application Some raw materials and their content and other parameters used in the preparation method of the isolation film of the present application can be referred to the isolation film of the first aspect of the embodiment of the application, and will not be described again here.
  • each raw material used in the preparation method of the isolation film of the present application can be obtained commercially.
  • a third aspect of the embodiment of the present application provides a secondary battery.
  • Secondary batteries also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
  • a secondary battery includes an electrode assembly and an electrolyte.
  • the electrode assembly includes a positive electrode piece, a negative electrode piece, and a separator.
  • the isolation film is disposed between the positive electrode piece and the negative electrode piece, It mainly plays the role of preventing short circuit between the positive and negative electrodes, and at the same time allows active ions to pass through.
  • the secondary battery may be a lithium-ion battery, a sodium-ion battery, etc.
  • the secondary battery may be a lithium-ion secondary battery.
  • the secondary battery of the third aspect of the embodiment of the present application includes the separator of the first aspect of the embodiment of the present application or a separator prepared by the method of the second aspect of the embodiment of the present application.
  • the separator film is spaced between the positive electrode plate and the between the negative electrode pieces.
  • at least the side of the isolation film close to the negative electrode piece has the coating of the present application. Therefore, the secondary battery of the present application can take into account high energy density, high thermal safety performance and long service life.
  • the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and including a positive active material.
  • the positive electrode current collector has two surfaces opposite in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive active material may include, but is not limited to, at least one of lithium-containing transition metal oxides, lithium-containing phosphates and their respective modified compounds.
  • the lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt At least one of manganese oxide, lithium nickel cobalt aluminum oxide and their respective modified compounds.
  • lithium-containing phosphate may include, but are not limited to, lithium iron phosphate, composites of lithium iron phosphate and carbon, lithium manganese phosphate, composites of lithium manganese phosphate and carbon, lithium iron manganese phosphate, lithium iron manganese phosphate and carbon. at least one of the composite materials and their respective modifying compounds.
  • the cathode active material for the lithium-ion battery may include a lithium transition metal oxide with the general formula Li a Ni b Co c M d O e Af and its at least one of the modified compounds. 0.8 ⁇ a ⁇ 1.2, 0.5 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1, 0 ⁇ d ⁇ 1, 1 ⁇ e ⁇ 2, 0 ⁇ f ⁇ 1, M is selected from Mn, Al, Zr, Zn, Cu, Cr , at least one of Mg, Fe, V, Ti and B, and A is selected from at least one of N, F, S and Cl.
  • a lithium transition metal oxide with the general formula Li a Ni b Co c M d O e Af and its at least one of the modified compounds. 0.8 ⁇ a ⁇ 1.2, 0.5 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1, 0 ⁇ d ⁇ 1, 1 ⁇ e ⁇ 2, 0 ⁇ f ⁇ 1, M is selected from Mn, Al, Zr, Zn, Cu, Cr , at least one of Mg, Fe, V, Ti and B, and A is
  • cathode active materials for lithium ion batteries may include LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), LiNi 0.5 Co 0.2 At least one of Mn 0.3 O 2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.85 Co 0.15 Al 0.05 O 2 , LiFePO 4 , and LiMnPO 4 kind.
  • the positive active material may include but is not limited to sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.) , at least one of Prussian blue materials.
  • cathode active materials for sodium ion batteries may include NaFeO 2 , NaCoO 2 , NaCrO 2 , NaMnO 2 , NaNiO 2 , NaNi 1/2 Ti 1/2 O 2 , NaNi 1/2 Mn 1/2 O 2 , Na 2/3 Fe 1/3 Mn 2/3 O 2 , NaNi 1/3 Co 1/3 Mn 1/3 O 2 , NaFePO 4 , NaMnPO 4 , NaCoPO 4 , Prussian blue materials, the general formula is X p M' q (PO 4 ) r O x Y 3-x at least one of the materials.
  • M' is a transition metal cation, optionally at least one of V, Ti, Mn, Fe, Co, Ni, Cu and Zn
  • Y is a halogen anion, optionally at least one of F, Cl and Br.
  • the modified compounds of each of the above-mentioned positive electrode active materials may be doping modifications and/or surface coating modifications of the positive electrode active materials.
  • the positive electrode film layer optionally further includes a positive electrode conductive agent.
  • a positive electrode conductive agent includes superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, and graphene. and at least one of carbon nanofibers.
  • the mass percentage of the cathode conductive agent is ⁇ 5%.
  • the positive electrode film layer optionally further includes a positive electrode binder.
  • the positive electrode binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene At least one of ethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the mass percentage of the cathode binder is ⁇ 5% based on the total mass of the cathode film layer.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • a metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the polymer material base layer may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and At least one of polyethylene (PE).
  • the positive electrode film layer is usually formed by coating the positive electrode slurry on the positive electrode current collector, drying, and cold pressing.
  • the positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder and any other components in a solvent and stirring evenly.
  • the solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative active material may be a negative active material known in the art for secondary batteries.
  • the negative active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate.
  • the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitride composite and silicon alloy material.
  • the tin-based material may include at least one of elemental tin, tin oxide and tin alloy materials.
  • the negative electrode film layer optionally further includes a negative electrode conductive agent.
  • a negative electrode conductive agent may include superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite at least one of ene and carbon nanofibers.
  • the mass percentage of the negative electrode conductive agent is ⁇ 5%.
  • the negative electrode film layer optionally further includes a negative electrode binder.
  • the negative electrode binder may include styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (for example, At least one of polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyacrylic acid sodium (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS). kind.
  • the mass percentage of the negative electrode binder is ⁇ 5%.
  • the negative electrode film layer optionally includes other additives.
  • other auxiliaries may include thickeners, such as sodium carboxymethylcellulose (CMC), PTC thermistor materials, and the like.
  • CMC sodium carboxymethylcellulose
  • PTC thermistor materials such as sodium carboxymethylcellulose (CMC)
  • the mass percentage of the other additives is ⁇ 2%.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil can be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the polymer material base layer may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and At least one of polyethylene (PE).
  • the negative electrode film layer is usually formed by coating the negative electrode slurry on the negative electrode current collector, drying, and cold pressing.
  • the negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring evenly.
  • the solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.
  • the negative electrode plate does not exclude other additional functional layers in addition to the negative electrode film layer.
  • the negative electrode sheet described in the present application further includes a conductive undercoat layer (for example, made of Conductive agent and adhesive).
  • the negative electrode sheet described in this application further includes a protective layer covering the surface of the negative electrode film layer.
  • the electrolyte solution includes electrolyte salts and solvents.
  • the types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.
  • the electrolyte salt may include but is not limited to lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), hexafluoroborate Lithium fluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonimide (LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB) ), at least one of lithium difluoroborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTF
  • the electrolyte salt may include but is not limited to sodium hexafluorophosphate (NaPF 6 ), sodium tetrafluoroborate (NaBF 4 ), sodium perchlorate (NaClO 4 ), sodium hexafluoromethanesulfonate (NaAsF 6 ), sodium bisfluorosulfonimide (NaFSI), sodium bistrifluoromethanesulfonimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), difluoroxalic acid boric acid At least one of sodium (NaDFOB), sodium dioxaloborate (NaBOB), sodium difluorophosphate (NaPO 2 F 2 ), sodium difluorodioxalophosphate (NaDFOP) and sodium tetrafluorooxalophosphate (NaTFOP).
  • NaPF 6 sodium hexafluorophosphate
  • NaBF 4 sodium tetra
  • the solvent may include, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), Dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), At least one of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sul
  • additives are optionally included in the electrolyte.
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery performance. Additives for low temperature power performance, etc.
  • the positive electrode piece, the isolation film and the negative electrode piece can be made into an electrode assembly through a winding process and/or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the soft bag may be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).
  • This application has no particular limitation on the shape of the secondary battery, which can be cylindrical, square or any other shape. As shown in FIG. 1 , a square-structured secondary battery 5 is shown as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 is used to cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process and/or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and can be adjusted according to needs.
  • the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte may be assembled to form a secondary battery.
  • the positive electrode sheet, isolation film, and negative electrode sheet can be formed into an electrode assembly through a winding process and/or a lamination process.
  • the electrode assembly is placed in an outer package, dried, and then injected with electrolyte. After vacuum packaging, static Through processes such as placement, formation, and shaping, secondary batteries are obtained.
  • the secondary batteries according to the present application can be assembled into battery modules.
  • the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 3 is a schematic diagram of the battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 arranged in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 is used to cover the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • a fourth aspect of the embodiments of the present application provides an electrical device, which includes at least one of a secondary battery, a battery module or a battery pack of the present application.
  • the secondary battery, battery module or battery pack may be used as a power source for the electrical device or as an energy storage unit for the electrical device.
  • the electrical device may be, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric Golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the power-consuming device can select a secondary battery, a battery module or a battery pack according to its usage requirements.
  • FIG. 6 is a schematic diagram of an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • battery packs or battery modules can be used.
  • the power-consuming device may be a mobile phone, a tablet computer, a laptop computer, etc.
  • the electrical device is usually required to be light and thin, and secondary batteries can be used as power sources.
  • Nanoscale cutting was performed to obtain nanocellulose C1 with an average length of 400 nm and an average diameter of 25 nm with a sulfonic acid group modified group, and the molar ratio of the sulfonic acid group to the hydroxyl group was 5:3.
  • Modified nanocellulose C2 to C4 were prepared according to a similar method to modified nanocellulose C1. The differences are detailed in Table 1. During the preparation process, modified nanocellulose with different average diameters and/or different average lengths can be obtained by adjusting the parameters of the grinder processing and the cutting parameters of the high-pressure homogenizer equipment.
  • the high-pressure homogenizer equipment performs nanoscale cutting to obtain nanocellulose with an amine-modified group with an average length of 400 nm and an average diameter of 25 nm, and the molar ratio of amine groups to hydroxyl groups is 4:3.
  • the molar ratio of the anionic modification group to the hydroxyl group can be measured by the following method: According to the phthalic anhydride method in GB/T 12008.3-2009, the hydroxyl value of the raw cellulose and modified nanocellulose (with each The number of milligrams of potassium hydroxide equivalent to the hydroxyl content in the gram sample), the numerical unit obtained is mg KOH/g, which is converted into mmol/g as the hydroxyl content. Subtracting the hydroxyl content of the modified nanocellulose from the hydroxyl content of the raw cellulose, the content of the anionic modification group (that is, the content of the modified hydroxyl group) can be obtained. From this, the anionic modification group and the hydroxyl group can be calculated. molar ratio.
  • Unmodified nanocellulose is used, with an average length of 400nm and an average diameter of 25nm.
  • the product model is CNWS-50, purchased from Zhongke Leiming (Beijing) Technology Co., Ltd., and can be further processed using a grinder and/or a high-pressure homogenizer to obtain nanocellulose with different average diameters and/or different average lengths.
  • the PE porous substrate has a thickness of 5 ⁇ m and a porosity of 40%.
  • Step 1 mix 10g modified nanocellulose C1 and 190g solvent water to prepare a nanocellulose solution with a pH of 7.5 and a Zeta potential of -35.7mV;
  • Step 2 add 102g of alumina dispersion with a solid content of 50wt% (Secondary particle morphology, average particle diameter is 180nm), add 6.6g of NaOH aqueous solution with a concentration of 10wt% and mix evenly to prepare a filler solution with a pH of 9.5 and a Zeta potential of -10.1mV;
  • step 3 add the prepared nanometer
  • the cellulose solution and the prepared filler solution are evenly mixed according to the solution mass ratio of 10:3 to form a mixed solution, and then 1wt% binder aqueous solution polyacrylic acid (based on the total weight of the dried coating) is added to the mixed solution. That is, the coating slurry is obtained.
  • the prepared coating slurry is coated on both surfaces of the PE porous substrate with a coater, and a separation film is obtained through drying and slitting processes.
  • the thickness of the coating located on one side of the PE porous substrate is 0.8 ⁇ m.
  • Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 30:70 to obtain an organic solvent.
  • Fully dried LiPF 6 was dissolved in the above organic solvent to prepare an electrolyte solution with a concentration of 1 mol/L.
  • the positive electrode sheet, isolation film, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in the outer packaging, dried and then injected with electrolyte. After vacuum packaging, standing, formation, shaping and other processes, Get a secondary battery.
  • the secondary battery was prepared using a method similar to Example 1, except that in the preparation of the separator, the preparation parameters of the coating slurry were different. See Table 2 for details.
  • the secondary battery was prepared using a method similar to Example 1, except that in the preparation of the separator, primary particle morphology of alumina was also added when preparing the coating slurry.
  • the specific parameters are shown in Table 2.
  • Step 1 mix 10g modified nanocellulose C1 and 190g solvent water to prepare a nanocellulose solution with a pH of 7.5 and a Zeta potential of -35.7mV;
  • Step 2 add 102g of alumina dispersion with a solid content of 50wt% (a mixture of secondary particle morphology and primary particle morphology, the mass ratio is 5:1, the average particle size of the secondary particles is 180nm, the average particle size of the primary particles is 400nm), add 6.6g of NaOH with a concentration of 10wt% Mix the aqueous solution evenly to prepare a filler solution with a pH of 9.5 and a Zeta potential of -10.1mV; step 3, mix the prepared nanocellulose solution and the prepared filler solution according to the solution mass ratio of 10:3 to form a mixed solution, and then Add 1 wt% binder aqueous solution polyacrylic acid (based on the total weight of the dried coating) to the mixed solution to obtain a coating slurry.
  • the secondary battery was prepared using a method similar to Example 1, except that in the preparation of the separator, unmodified nanocellulose C6 and unmodified primary particle morphology alumina were used when preparing the coating slurry. , see Table 2 for specific parameters.
  • Step 1 mix 10g of unmodified nanocellulose C6 and 190g of solvent water to prepare a nanocellulose solution with a pH of 8.6 and a zeta potential of 20.5mV;
  • Step 2 mix 102g of alumina dispersion with a solid content of 50wt% (Primary particle morphology, the average particle size of the primary particles is 800nm) as a filler solution, with a pH of 7.4 and a Zeta potential of -5.5mV;
  • step 3 combine the prepared nanocellulose solution and the prepared filler solution according to the solution Mix evenly to form a mixed liquid with a mass ratio of 10:3, and then add 1wt% binder aqueous solution polyacrylic acid (based on the total weight of the dried coating) into the mixed liquid to obtain a coating slurry.
  • the secondary battery was prepared using a method similar to Example 1, except that in the preparation of the separator, unmodified nanocellulose C6 was used to prepare the coating slurry and oxidation of unmodified secondary particle morphology was used.
  • Aluminum please see Table 2 for specific parameters.
  • Step 1 mix 10g of unmodified nanocellulose C6 and 190g of solvent water to prepare a nanocellulose solution with a pH of 8.6 and a zeta potential of 20.5mV;
  • Step 2 mix 102g of alumina dispersion with a solid content of 50wt% (Secondary particle morphology, the average particle size of the secondary particles is 180nm) as a filler solution, with a pH of 5.6 and a Zeta potential of 39.3mV;
  • Step 3 combine the prepared nanocellulose solution and the prepared filler solution according to Mix the solution with a mass ratio of 10:3 evenly to form a mixed solution, and then add 1wt% binder aqueous solution polyacrylic acid (based on the total weight of the dried coating) into the mixed solution to obtain a coating slurry.
  • the secondary battery was prepared using a method similar to Example 1, except that in the preparation of the separator, unmodified nanocellulose C6 was used when preparing the coating slurry.
  • the specific parameters are shown in Table 2.
  • Step 1 mix 10g of unmodified nanocellulose C6 and 190g of solvent water to prepare a nanocellulose solution with a pH of 8.6 and a zeta potential of 20.5mV;
  • Step 2 add 102g of alumina dispersion with a solid content of 50wt% (Secondary particle morphology, average particle diameter is 180nm), add 6.6g of NaOH aqueous solution with a concentration of 10wt% and mix evenly to prepare a filler solution with a pH of 9.5 and a Zeta potential of -10.1mV;
  • step 3 add the prepared nanometer
  • the cellulose solution and the prepared filler solution are evenly mixed according to the solution mass ratio of 10:3 to form a mixed solution, and then 1wt% binder aqueous solution polyacrylic acid (based on the total weight of the dried coating) is added to the mixed solution. That is, the coating slurry is obtained.
  • the secondary battery was prepared using a method similar to Example 1, except that in the preparation of the separator, unmodified alumina with secondary particle morphology was used when preparing the coating slurry.
  • the specific parameters are shown in Table 2.
  • Step 1 mix 10g modified nanocellulose C1 and 190g solvent water to prepare a nanocellulose solution with a pH of 7.5 and a zeta potential of -35.7mV;
  • Step 2 mix 102g of alumina dispersion with a solid content of 50wt% (Secondary particle morphology, the average particle size of the secondary particles is 180nm) as a filler solution, with a pH of 5.6 and a Zeta potential of 39.3mV;
  • Step 3 combine the prepared nanocellulose solution and the prepared filler solution according to Mix the solution with a mass ratio of 10:3 evenly to form a mixed solution, and then add 1wt% binder aqueous solution polyacrylic acid (based on the total weight of the dried coating) into the mixed solution to obtain a coating slurry.
  • a blade to scrape 30g of coating material powder from the prepared isolation film (the scraping depth does not exceed the boundary area between the coating and the porous substrate), and then mix it with 2000g of deionized water using a stirrer with a toothed disc. After stirring at a certain stirring speed (for example, it can be 2000r/min), a dispersion is obtained (the stirring time can be, for example, 1.5 hours). The obtained dispersion is placed in a sample cell, and then tested using a Zeta potentiometer to obtain the dispersion. Zeta potential is the Zeta potential of the coating.
  • the sample cell can use Malvern's DTS1070 Zeta potential capillary sample cell, and the Zeta potential meter can use Malvern's Zetasizer Advance nanoparticle size potentiometer.
  • test results For testing standards, please refer to GB/T 32671.2-2019 and ISO 13099-2-2012. For accuracy, 5 parallel samples can be taken for testing and the average value is taken as the test result.
  • Each of the above solutions was placed in a sample cell, and then tested using a Zeta potential meter to obtain the Zeta potential of each solution.
  • the sample cell can use Malvern's DTS1070 Zeta potential capillary sample cell, and the Zeta potential meter can use Malvern's Zetasizer Advance nanoparticle size potentiometer.
  • For testing standards please refer to GB/T 32671.2-2019 and ISO 13099-2-2012. For accuracy, 5 parallel samples can be taken for testing and the average value is taken as the test result.
  • Sample preparation Use a punch machine to punch the isolation film prepared above into samples with a width of 50mm and a length of 100mm. Take 5 parallel samples and place them on A4 paper and fix them. Then place the A4 paper containing the samples on a layer with a thickness of 1mm to 5mm corrugated paper.
  • Sample test Set the temperature of the blast oven to 150°C. After the temperature reaches the set temperature and stabilizes for 30 minutes, start timing. Place the A4 paper placed on the corrugated paper into the blast oven until the set time is reached (this application After 1h), measure the length and width of the isolation film, and the values are marked a and b respectively.
  • the testing instrument can be Xionggu KRK Wangyan air permeability tester.
  • the coatings of the isolation films prepared in Comparative Examples 1 to 4 do not satisfy the Zeta potential of less than 0 mV. Therefore, the isolation film cannot achieve both low thermal shrinkage and high air permeability, and the secondary battery cannot achieve both high thermal safety performance and good cycle. performance.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Inorganic Chemistry (AREA)
  • Cell Separators (AREA)
  • Secondary Cells (AREA)

Abstract

本申请提供一种隔离膜、其制备方法及其相关的二次电池和用电装置，所述隔离膜包括多孔基材和设置在所述多孔基材的至少一个表面上的涂层，其中，所述涂层包括三维骨架结构和填料，所述填料中的至少一部分填充在所述三维骨架结构中，并且所述涂层的Zeta电位为小于0mV。本申请提供的隔离膜具有耐热性优良、均一性好和离子导通性好等特点，从而使得使用该隔离膜的二次电池可兼顾高能量密度、高热安全性能和长使用寿命。

Description

隔离膜、其制备方法及其相关的二次电池和用电装置
相关申请的交叉引用
本申请要求享有于2022年06月24日提交的名称为“一种隔离膜、其制备方法及其相关的二次电池和用电装置”的专利申请PCT/CN2022/101261的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请属于电池技术领域，具体涉及一种隔离膜、其制备方法及其相关的二次电池和用电装置。
背景技术
近年来，二次电池被广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。随着二次电池的应用及推广，其安全问题，特别是热安全问题受到越来越多的关注。然而，目前用于提高二次电池热安全性能的方式往往不利于平衡二次电池的能量密度和容量发挥。因此，如何使二次电池兼顾高能量密度、高热安全性能和长使用寿命是二次电池设计的关键挑战所在。
发明内容
本申请的目的在于提供一种隔离膜、其制备方法及其相关的二次电池和用电装置，该隔离膜具有耐热性优良、均一性好和离子导通性好等特点，从而使得使用该隔离膜的二次电池可兼顾高能量密度、高热安全性能和长使用寿命。
本申请第一方面提供一种隔离膜，包括多孔基材和设置在所述多孔基材的至少一个表面上的涂层，其中，所述涂层包括三维骨架结构和填料，所述填料中的至少一部分填充在所述三维骨架结构中，并且所述涂层的Zeta电位为小于0mV。所述涂层的Zeta电位通过如下方法测试得到：取30g涂层材料粉末与2000g去离子水搅拌混合后得到分散液，通过Zeta电位仪测试所获得的分散液的Zeta电位，即为所述涂层的Zeta电位。
在本申请提供的隔离膜中，当涂层的Zeta电位在合适的范围内时，涂层浆料具有良好的分散性，由此涂层浆料干燥后可形成面密度和厚度均一性好的涂层，提升隔离膜的耐热性，同时涂层孔隙分布均匀，可确保涂层离子导通性好，从而可以提高二次电池的倍率性能、热安全性能和循环性能。填料中的至少一部分填充在三维骨架结构中，由此有助于填料与三维骨架结构形成嵌套效果，从而既能增加隔离膜的耐热性，降低隔离膜受热时的收缩程度，降低正极和负极短路风险，使二次电池具有高热安全性能，又能使涂层与多孔基材之间保持高粘结强度，避免填料在二次电池长期充放电过程中脱落。填 料中的至少一部分填充在三维骨架结构中，由此填料还能够与三维骨架结构搭接在一起，从而能使涂层具有稳定的空间网络结构，既能增加隔离膜的离子导通通道、促进离子传输，又能提升隔离膜对电解液的浸润和保持特性，进而采用本申请的隔离膜的二次电池可具有长使用寿命。由于本申请的涂层具有高耐热性，由此可以选用更薄的多孔基材，进而采用本申请的隔离膜的二次电池还能够兼顾高能量密度。
在本申请的任意实施方式中，所述涂层的Zeta电位为-50mV至-5mV，可选为-25mV至-5mV。由此有助于进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，从而能够进一步提升隔离膜的离子导通性以及二次电池的能量密度和循环性能。
在本申请的任意实施方式中，构成所述三维骨架结构的材料包括有机棒状物和有机管状物中的至少一种。合适形状的材料有利于三维骨架结构与填料更好地搭接在一起，从而能使涂层具有更稳定的空间网络结构，由此能够进一步提升隔离膜的耐热性和离子导通性。
在本申请的任意实施方式中，构成所述三维骨架结构的材料包括纳米纤维素、聚四氟乙烯纳米纤维和聚酰胺纳米纤维中的至少一种，可选地，所述纳米纤维素包括纤维素纳米纤维、纤维素纳米晶须和细菌纳米纤维素中的至少一种。
在本申请的任意实施方式中，构成所述三维骨架结构的材料包括纳米纤维素，所述纳米纤维素包括羟基和阴离子改性基团，可选地，所述阴离子改性基团包括胺基、羧基、磺酸基、硼酸基和磷酸基中的至少一种，更可选包括磺酸基、硼酸基和磷酸基中的至少一种。当纳米纤维素具有上述特定的阴离子改性基团时，能够保证涂层浆料具有合适的粘度，更有利于涂布，从而能提高隔离膜的生产效率；同时还有助于涂层具有合适的Zeta电位，从而能进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，进而能够进一步提升隔离膜的离子导通性以及二次电池的能量密度和循环性能。
在本申请的任意实施方式中，所述阴离子改性基团与所述羟基的摩尔比为1:4至4:1，可选为2:3至7:3。由此能够进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，以及提升隔离膜的耐热性、离子导通性和对电解液的浸润和保持特性。
在本申请的任意实施方式中，构成所述三维骨架结构的材料的平均直径为≤40nm，可选为10nm至35nm。由此能够进一步提高隔离膜的离子导通性和耐电压击穿特性，同时还有助于构成所述三维骨架结构的材料与填料搭接形成一体化效果，由此还能够进一步提升隔离膜的耐热性。
在本申请的任意实施方式中，构成所述三维骨架结构的材料的平均长度为100nm至600nm，可选为200nm至400nm。由此能够进一步提高隔离膜的耐热性和离子导通性。
在本申请的任意实施方式中，构成所述三维骨架结构的材料的长径比为5至60，可选为15至30。由此能够进一步提高隔离膜的离子导通性。
在本申请的任意实施方式中，所述填料包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒中的至少一种，可选地，所述填料包括二次颗粒形貌的填料颗粒，进一步可选地，所述填料同时包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒。
在本申请的任意实施方式中，所述一次颗粒形貌的填料颗粒的平均粒径为200nm至800nm，可选为200nm至400nm。
在本申请的任意实施方式中，所述一次颗粒形貌的填料颗粒的BET比表面积为≤10m 2/g，可选为3m 2/g至7m 2/g。
在本申请的任意实施方式中，所述一次颗粒形貌的填料颗粒的含量为≤30wt％，可选为5wt％至25wt％，基于所述涂层的总重量计。
一次颗粒形貌的填料颗粒的粒径较大，由此能够更好地发挥其在涂层中的支撑作用，减少二次颗粒形貌的填料颗粒的收缩，降低粘结剂用量，从而提升隔离膜的耐热性；一次颗粒形貌的填料颗粒的粒径较大，有助于在用量较少时使涂层具有更多的孔道结构和更少的水含量，进而能够进一步提升隔离膜的离子导通性以及对电解液的浸润和保持特性。
在本申请的任意实施方式中，所述二次颗粒形貌的填料颗粒的平均粒径为≤200nm，可选为50nm至200nm。
在本申请的任意实施方式中，所述二次颗粒形貌的填料颗粒的BET比表面积为≥20m 2/g，可选为30m 2/g至80m 2/g。
在本申请的任意实施方式中，所述二次颗粒形貌的填料颗粒的含量为≥60wt％，可选为70wt％至90wt％，基于所述涂层的总重量计。
二次颗粒形貌的填料颗粒具有比表面积大、与三维骨架结构亲和性好的优势，由此能够与三维骨架结构更好地搭接在一起，使涂层具有更稳定的空间网络结构，从而既能增加隔离膜的离子导通通道、促进离子传输，又能提升隔离膜的耐热性对电解液的浸润和保持特性，由此采用本申请的隔离膜的二次电池能可具有长使用寿命和良好的倍率性能。
在本申请的任意实施方式中，所述填料同时包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒，且所述二次颗粒形貌的填料颗粒与所述一次颗粒形貌的填料颗粒的质量比为2:1至27:1，可选为5:1至15:1。由此，有助于涂层具有稳定性更高和均一性更好的空间网络结构。
在本申请的任意实施方式中，所述填料包括无机颗粒和有机颗粒中的至少一种。可选地，所述无机颗粒包括选自具有5或更高的介电常数的无机颗粒、具有传输活性离子能力的无机颗粒、能够发生电化学氧化和还原的无机颗粒中的至少一种。可选地，所述有机颗粒包括选自聚苯乙烯、聚乙烯、聚酰亚胺、三聚氰胺树脂、酚醛树脂、聚丙烯、聚酯、聚苯硫醚、聚芳酰胺、聚酰胺酰亚胺、聚酰亚胺、丙烯酸丁酯与甲基丙烯酸乙酯的共聚物及其混合物中的至少一种。
在本申请的任意实施方式中，所述涂层中的所述三维骨架结构的含量为6wt％至35wt％，可选为10wt％至30wt％，基于所述涂层的总重量计。由此能够保证涂层浆料具有合适的粘度，更有利于涂布；此外，还有利于三维骨架结构与填料搭接形成一体化效果，由此能使涂层具有更稳定的空间网络结构。
在本申请的任意实施方式中，所述三维骨架结构与所述填料的质量比为1:2至1:15.5，可选为1:5至1:10。由此有助于涂层具有合适的Zeta电位，从而能进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，从而能够进一步提升隔离膜的离子导通性以及二次电池的能量密度和循环性能。
在本申请的任意实施方式中，所述涂层还包括非颗粒状的粘结剂。可选地，所述非颗粒状的粘结剂包括水溶液型粘结剂。
在本申请的任意实施方式中，所述涂层中的所述非颗粒状的粘结剂的含量为≤2wt％，基于所述涂层的总重量计。本申请的涂层中的三维骨架结构与填料能够搭接在一起使涂层具有稳定的空间网络结构，由此能够在减少粘结剂用量的前提下使隔离膜还能保持高粘结性。
在本申请的任意实施方式中，所述多孔基材的厚度为≤6μm，可选为3μm至5μm。由此有助于提升二次电池的能量密度。
在本申请的任意实施方式中，所述涂层的厚度为≤1μm，可选为0.5μm至0.8μm。由此有助于提升二次电池的能量密度。
在本申请的任意实施方式中，所述隔离膜还包括粘接层，所述粘接层设置在所述涂层的至少一部分表面上，所述粘接层包括颗粒状的粘结剂。可选地，所述颗粒状的粘结剂包括丙烯酸酯类单体均聚物或共聚物、丙烯酸类单体均聚物或共聚物、含氟烯烃单体均聚物或共聚物中的至少一种。粘接层不仅能够防止涂层脱落，提高涂层与多孔基材的粘结性和二次电池的安全性能，而且能够改善隔离膜与电极的界面，提升二次电池的循环性能。
在本申请的任意实施方式中，所述隔离膜在150℃、1h下的纵向热收缩率为≤5％，可选为0.5％至3％。
在本申请的任意实施方式中，所述隔离膜在150℃、1h下的横向热收缩率为≤5％，可选为0.5％至3％。
在本申请的任意实施方式中，所述隔离膜的纵向拉伸强度为≥2000kg/cm 2，可选为2500kg/cm 2至4500kg/cm 2。
在本申请的任意实施方式中，所述隔离膜的横向拉伸强度为≥2000kg/cm 2，可选为2500kg/cm 2至4500kg/cm 2。
在本申请的任意实施方式中，所述隔离膜的润湿长度为≥30mm，可选为30mm至80mm。
在本申请的任意实施方式中，所述隔离膜的润湿速度为≥3mm/s，可选为3mm/s至10mm/s。
在本申请的任意实施方式中，所述隔离膜的透气度为≤300s/100mL，可选为100s/100mL至230s/100mL。
当隔离膜的性能满足上述条件中的一个或几个时，有利于提升二次电池的能量密度、热安全性能和使用寿命中的至少一者。
本申请第二方面提供一种制备本申请第一方面的隔离膜的方法，包括以下步骤：S1，提供多孔基材；S2，配制涂层浆料，将用于构成三维骨架结构的材料和填料按照预定比例在溶剂中混合，配制成涂层浆料；S3，涂布，将所述涂层浆料涂布于所述多孔基材的至少一个表面上，形成涂层并干燥，获得隔离膜，其中，所述隔离膜包括多孔基材和设置在所述多孔基材的至少一个表面上的涂层，所述涂层包括三维骨架结构和填料，所述填料中的至少一部分填充在所述三维骨架结构中，并且所述涂层的Zeta电位为小于0mV。所述涂层的Zeta电位通过如下方法测试得到：取30g涂层材料粉末与2000g去离子水搅拌 混合后得到分散液，通过Zeta电位仪测试所获得的分散液的Zeta电位，即为所述涂层的Zeta电位。
在本申请的任意实施方式中，所述涂层浆料的pH为5至10，可选为6至9。
在本申请的任意实施方式中，所述涂层浆料的静态粘度在1000mpa.s以下。
在本申请的任意实施方式中，所述涂层浆料通过以下方式获得：步骤1，配制纳米纤维素溶液，将具有阴离子改性基团的纳米纤维素与水混合配制成所述纳米纤维素溶液，其中，所述纳米纤维素溶液的pH在5至9之间、Zeta电位为小于0mV；步骤2，配制填料溶液，所述填料溶液的pH为≥7.5、Zeta电位为小于0mV；步骤3，混合，将所述纳米纤维素溶液和所述填料溶液按照预定比例混合，即得到涂层浆料，其中，所述涂层浆料的Zeta电位在-5mV以下。
在本申请的任意实施方式中，所述纳米纤维素溶液的浓度为1wt％至10wt％，可选为2wt％至10wt％。
在本申请的任意实施方式中，所述填料溶液的浓度为30wt％至60wt％，可选为35wt％至55wt％。
在本申请的任意实施方式中，所述具有阴离子改性基团的纳米纤维素通过以下方式获得：将纳米纤维素粉末与改性溶液混合并反应后，经过洗涤除杂，获得具有阴离子改性基团的纤维素纳米晶须，将所获得的具有阴离子改性基团的纤维素纳米晶须的pH调节至中性，并经研磨、切割获得具有阴离子改性基团的纳米纤维素。可选地，所述改性溶液为硫酸水溶液、硼酸水溶液、磷酸水溶液、醋酸水溶液或尿素有机溶剂溶液。
在本申请的任意实施方式中，所述填料溶液通过以下方式获得：将填料、水与改性剂混合，获得pH为≥7.5、Zeta电位为小于0mV的填料溶液，所述改性剂包括选自碱、阴离子表面活性剂和非离子表面活性剂中的至少一种。
在本申请的任意实施方式中，所述碱包括选自KOH、NaOH、NaHCO 3、LiOH、NH 4OH、Mg(OH) 2和Na 2CO 3中的至少一种。
在本申请的任意实施方式中，所述阴离子表面活性剂包括选自磺酸盐型阴离子表面活性剂、羧酸盐型阴离子表面活性剂、硫酸酯盐型阴离子表面活性剂和磷酸酯盐型阴离子表面活性剂中的至少一种，可选为包括选自烷基苯磺酸盐、C12-C20烷基磺酸盐、聚丙烯酸钠、聚丙烯酸铵、羟乙基硫酸钠和C12-C20烷基硫酸钠中的至少一种。
在本申请的任意实施方式中，所述非离子表面活性剂包括选自氟代烷基乙氧基醇醚和脂肪醇聚氧乙烯醚中的至少一种。
在本申请的任意实施方式中，所述方法还包括以下步骤：S4，二次涂布，将包含颗粒状的粘结剂的浆料涂布于所述涂层的至少一部分表面上，干燥后形成粘接层。
本申请的隔离膜的制备方法通过一次涂布制得涂层，大大简化了隔离膜的生产工艺流程。
本申请第三方面提供一种二次电池，包括本申请第一方面的隔离膜或通过本申请第二方面的方法制备的隔离膜。
本申请第四方面提供一种用电装置，包括本申请第三方面的二次电池。
本申请通过在隔离膜的多孔基材表面设置包括三维骨架结构和填料的涂层，并调节涂层的Zeta电位为小于0mV，能够使隔离膜兼顾高耐热性、高均一性和良好的离子导通 性，进而能够使二次电池兼顾高能量密度、高热安全性能和长使用寿命。本申请的用电装置包括本申请提供的二次电池，因而至少具有与所述二次电池相同的优势。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍。显而易见地，下面所描述的附图仅仅是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请的二次电池的一实施方式的示意图。
图2是图1的二次电池的实施方式的分解示意图。
图3是本申请的电池模块的一实施方式的示意图。
图4是本申请的电池包的一实施方式的示意图。
图5是图4所示的电池包的实施方式的分解示意图。
图6是包含本申请的二次电池作为电源的用电装置的一实施方式的示意图。
在附图中，附图未必按照实际的比例绘制。附图标记说明如下：1电池包，2上箱体，3下箱体，4电池模块，5二次电池，51壳体，52电极组件，53盖板。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的隔离膜、其制备方法及其相关的二次电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案，并且这样的技术方案应被认为包含在本申请的公开内容中。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案，并且这样的技术方案应被认为包含在本申请的公开内容中。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是 顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
在本申请中，术语“多个”、“多种”是指两个或两种以上。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。
除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测试方法进行测定，例如，可以按照本申请的实施例中给出的测试方法进行测定。
通常情况下，二次电池包括电极组件和电解液，电极组件包括正极极片、负极极片和隔离膜，隔离膜设置在正极极片和负极极片之间，主要起到防止正极和负极短路的作用，同时可以使活性离子自由通过形成回路。
随着二次电池的应用及推广，人们对二次电池能量密度和使用寿命的要求越来越高。隔离膜减薄是提升二次电池能量密度的一个有效措施。目前商业化二次电池采用的隔离膜通常为聚烯烃多孔膜，例如聚乙烯多孔膜、聚丙烯多孔膜或聚丙烯/聚乙烯/聚丙烯三层复合膜，其熔点在130℃至160℃之间，由此，当其厚度减薄后，隔离膜的耐热性变差，受热时会发生明显的热收缩效应从而使得电池内部正极和负极直接接触导致内短路产生，进而增加了二次电池的安全风险。
为了解决上述问题，目前采用的措施主要是在聚烯烃多孔膜上涂布一层耐热性的无机陶瓷层，其能增加隔离膜的机械强度、减少隔离膜在受热时的收缩程度，降低电池内部正极和负极短路风险。但是，市售无机陶瓷颗粒的粒径较大，由此会增加隔离膜整体厚度，导致无法平衡二次电池的能量密度，特别是在动力电池领域，不利于续航里程提升；此外，由于市售无机陶瓷颗粒的粒径较大，由此其在聚烯烃多孔膜上的堆积层数较少(通常为≤5层)，进而导致其对隔离膜耐热性的改善效果有限。无机陶瓷颗粒纳米化可以降低涂层厚度，缓解对二次电池能量密度的不利影响，但是纳米化无机陶瓷颗粒形成的涂层孔隙率低且容易堵塞聚烯烃多孔膜，由此导致隔离膜整体的孔隙率降低、离子阻抗增加、离子传输受阻，进而导致二次电池的容量发挥和动力学性能变差。同时，由于纳米化无机陶瓷颗粒的比表面积较高，且颗粒之间的接触形式为点接触，由此需要使用大量粘结剂以保证颗粒之间的粘结性，但是粘结剂用量较大时易出现堵孔问题，从而对二次电池的倍率性能不利，例如负极表面容易形成枝晶，进而还对二次电池的容量发挥、能量密度和使用寿命不利。
此外，聚烯烃多孔膜为疏水性材料，而无机陶瓷颗粒为亲水性材料，因此在将无机 陶瓷浆料涂布于聚烯烃多孔膜表面时还会存在漏涂、均一性差等问题，由此影响了隔离膜的均一性，进而影响了二次电池的容量发挥和动力学性能。
因此，现有技术的隔离膜往往很难兼顾二次电池的高能量密度、高热安全性能和长使用寿命。
本申请的发明人在研究过程中惊奇发现，通过在隔离膜多孔基材表面设置包括三维骨架结构和填料的涂层，并调节涂层的Zeta电位在合适的范围内，能够使隔离膜兼顾高耐热性、高均一性和良好的离子导通性，进而能够使二次电池兼顾高能量密度、高热安全性能和长使用寿命。
隔离膜
具体地，本申请实施方式第一方面提供了一种隔离膜，包括多孔基材和设置在所述多孔基材的至少一个表面上的涂层，其中，所述涂层包括三维骨架结构和填料，所述填料中的至少一部分填充在所述三维骨架结构中，并且所述涂层的Zeta电位为小于0mV。
所述涂层的Zeta电位通过如下方法测试得到：取30g涂层材料粉末与2000g去离子水搅拌混合后得到分散液，通过Zeta电位仪测试所获得的分散液的Zeta电位，即为所述涂层的Zeta电位。
涂层材料粉末可以通过刮粉(例如刀片刮粉)取样方式获得，并且刮粉深度不超过涂层与多孔基材之间的分界区。分散液可以通过带齿盘的搅拌器充分搅拌后获得，搅拌时间可为1小时至3小时，搅拌速度可为1500r/min至3000r/min。
Zeta电位仪可为采用马尔文公司的Zetasizer系列纳米粒度电位仪，例如Zetasizer Advance纳米粒度电位仪，样品池可以采用马尔文公司的DTS1070 Zeta电位毛细管样品池。具体地，可将所获得的分散液置于马尔文公司的DTS1070 Zeta电位毛细管样品池中进行测试，然后通过ZS Xplorer软件测试所获得的分散液的Zeta电位。测试标准可参考GB/T 32671.2-2019和ISO 13099-2-2012。为了保证测试结果的准确性，测试时可取多个(例如5个以上)平行样品进行测试然后取平均值。
本申请的发明人经大量研究意外发现，通过在隔离膜的多孔基材表面设置包括三维骨架结构和填料的涂层，并调节涂层的Zeta电位为小于0mV，能够使隔离膜兼顾高耐热性、高均一性和良好的离子导通性，进而能够使二次电池兼顾高能量密度、高热安全性能和长使用寿命。
尽管机理尚不十分明确，本申请的发明人推测可能的原因包括如下几点。
第一，涂层的Zeta电位在合适的范围内时，涂层浆料具有良好的分散性，由此涂层浆料干燥后可形成面密度和厚度均一性好的涂层，提升隔离膜的耐热性，同时涂层孔隙分布均匀，可确保涂层离子导通性好，从而可以提高二次电池的倍率性能、热安全性能和循环性能。
第二，填料中的至少一部分填充在三维骨架结构中，由此有助于填料与三维骨架结构形成嵌套效果，从而既能增加隔离膜的耐热性，降低隔离膜受热时的收缩程度，降低正极和负极短路风险，使二次电池具有高热安全性能，又能使涂层与多孔基材之间保持高粘结强度，避免填料在二次电池长期充放电过程中脱落。
第三，填料中的至少一部分填充在三维骨架结构中，由此填料还能够与三维骨架结构搭接在一起，从而能使涂层具有稳定的空间网络结构，既能增加隔离膜的离子导通通 道、促进离子传输，又能提升隔离膜对电解液的浸润和保持特性，进而采用本申请的隔离膜的二次电池可具有长使用寿命。
第四，由于本申请的涂层具有高耐热性，由此可以选用更薄的多孔基材，进而采用本申请的隔离膜的二次电池还能够兼顾高能量密度。
在一些实施例中，所述涂层的Zeta电位可为-50mV至-5mV，可选为-25mV至-5mV，更可选为-15mV至-6mV。由此有助于进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，从而能够进一步提升隔离膜的离子导通性以及二次电池的能量密度和循环性能。并且能够有效避免以下情况：当涂层的Zeta电位过低时，涂层浆料粘度可能过大、流动性过差，由此可能会影响涂层浆料的涂布进而影响涂层面密度和厚度的均一性以及孔隙的均匀性。
在一些实施例中，构成所述三维骨架结构的材料可包括有机棒状物和有机管状物中的至少一种。合适形状的材料有利于三维骨架结构与填料更好地搭接在一起，从而能使涂层具有更稳定的空间网络结构，由此能够进一步提升隔离膜的耐热性和离子导通性。
在一些实施例中，构成所述三维骨架结构的材料可包括纳米纤维素、聚四氟乙烯纳米纤维和聚酰胺纳米纤维中的至少一种。
在一些实施例中，构成所述三维骨架结构的材料可包括纳米纤维素。可选地，所述纳米纤维素包括纤维素纳米纤维(Cellulose nanofibrils，CNF，又称为纳米纤丝纤维素或微纤化纤维素)、纤维素纳米晶须(Cellulose nanocrystals，CNC，又称为纤维素纳米晶、纳米晶体纤维素)和细菌纳米纤维素(Bacterial nanocellulose，BNC，又称为细菌纤维素或微生物纤维素)中的至少一种。可选地，所述纳米纤维素包括纤维素纳米晶须，其具有结晶度高的优势，由此能够更好地改善隔离膜的耐热性。
纳米纤维素是指任一维尺寸在纳米级(例如100nm以内)的纤维素的总称，其既具有纤维素的特性，又具有纳米颗粒的特性。纳米纤维素可以是通过化学、物理、生物等中的一种或多种手段从自然界中的木材、棉花等提取出的高分子纳米材料，具有来源广泛、成本低、生物可降解、模量高、比表面积高等优势，因此其是传统石化资源的优良替代品，可以有效地缓解环境污染和石化资源紧张等问题。
在一些实施例中，所述纳米纤维素可包括羟基和阴离子改性基团，可选地，所述阴离子改性基团包括胺基、羧基、磺酸基、硼酸基和磷酸基中的至少一种，更可选包括磺酸基、硼酸基和磷酸基中的至少一种。
发明人在进一步研究中发现，当纳米纤维素具有上述特定的阴离子改性基团时，能够保证涂层浆料具有合适的粘度，更有利于涂布，从而能提高隔离膜的生产效率；同时还有助于涂层具有合适的Zeta电位，从而能进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，进而能够进一步提升隔离膜的离子导通性以及二次电池的能量密度和循环性能。
当纳米纤维素具有上述特定的阴离子改性基团时，还能够有效提高隔离膜的耐热性，以及涂层与多孔基材之间的粘结强度。
当纳米纤维素具有上述特定的阴离子改性基团时，还有利于纳米纤维素与填料搭接在一起，从而能使涂层具有更稳定的空间网络结构，并提高隔离膜对电解液的浸润和保 持特性，从而还能够进一步提升隔离膜的离子导通性和耐电压击穿特性，由此有利于匹配高电压正极活性材料，并进一步提升二次电池的能量密度。
在一些实施例中，所述阴离子改性基团与所述羟基的摩尔比可为1:4至4:1，可选为2:3至7:3。当阴离子改性基团与羟基的摩尔比在合适的范围内时，能够进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，以及提升隔离膜的耐热性、离子导通性和对电解液的浸润和保持特性。并且能够有效避免以下情况：当阴离子改性基团与羟基的摩尔比过小时，阴离子改性基团所起到的对涂层面密度和厚度的均一性以及孔隙的均匀性的进一步改善效果可能不明显；当阴离子改性基团与羟基的摩尔比过大时，隔离膜对电解液的浸润和保持特性可能变差，进而可能影响二次电池的循环性能和安全性能，同时还可能导致隔离膜的耐热性下降，进而还可能影响二次电池的热安全性能。
纳米纤维素中阴离子改性基团的种类可以采用红外光谱法进行测定。例如，可以测试材料的红外光谱，确定其包含的特征峰，从而确定阴离子改性基团的种类。具体地，可以用本领域公知的仪器及方法对材料进行红外光谱法分析，例如采用红外光谱仪(如美国尼高力公司的IS10型傅里叶变换红外光谱仪)，依据GB/T 6040-2019红外光谱分析方法通则进行测试。
在一些实施例中，构成所述三维骨架结构的材料的平均直径可为≤40nm，可选为10nm至35nm。当构成三维骨架结构的材料的平均直径在合适的范围内时，能够进一步提高隔离膜的离子导通性和耐电压击穿特性，同时还有助于构成所述三维骨架结构的材料与填料搭接形成一体化效果，由此还能够进一步提升隔离膜的耐热性。并且能够有效避免以下情况：当构成三维骨架结构的材料的平均直径过大时，其形成的三维骨架结构的相互缠绕效果不足且孔隙较大，由此可能导致隔离膜的耐电压击穿特性不够优异。
在一些实施例中，构成所述三维骨架结构的材料的平均长度可为100nm至600nm，可选为200nm至400nm。当构成三维骨架结构的材料的平均长度在合适的范围内时，能够进一步提高隔离膜的耐热性和离子导通性。并且能够有效避免以下情况：当构成三维骨架结构的材料的平均长度过短时，其与填料的搭接效果较差，涂层的耐热性可能变差，并且在涂层烘干过程中，部分三维骨架结构由于缺少填料的支撑作用还容易坍塌，由此还容易堵多孔基材的微孔，阻碍离子传输和水分排出，从而还可能影响二次电池的循环性能和倍率性能；当构成三维骨架结构的材料的平均长度过长时，涂层浆料粘度高、分散性差，由此涂层浆料干燥后形成的涂层的面密度和厚度均一性以及孔隙的均匀性可能变差。
在一些实施例中，构成所述三维骨架结构的材料的长径比可为5至60，可选为15至30。当构成三维骨架结构的材料的长径比在合适的范围内时，能够进一步提高隔离膜的离子导通性。并且能够有效避免以下情况：当构成三维骨架结构的材料的长径比过小时，其与填料的搭接效果较差，涂层的耐热性可能变差，并且在涂层烘干过程中，部分三维骨架结构由于缺少填料的支撑作用还容易坍塌，由此还容易堵多孔基材的微孔，阻碍离子传输和水分排出，从而可能影响二次电池的循环性能和倍率性能；当构成三维骨架结构的材料的长径比过大时，其形成的三维骨架结构的孔隙较小，由此可能导致隔离膜的离子导通性变差。
构成三维骨架结构的材料的平均长度和平均直径可以通过以下方法进行测定：从隔离膜中任选一区域裁切出3.6mm×3.6mm的样品，利用扫描电子显微镜(例如ZEISS Sigma 300)测绘样品中涂层的微观形貌结构，选择高真空模式，工作电压为3kV，放大倍数为3万倍，获得SEM图；根据获得的SEM图，选取多个(例如5个以上)测试区域进行长度的统计，每个测试区域的尺寸为0.5μm×0.5μm，之后取各个测试区域得到的长度的平均值作为构成三维骨架结构的材料的平均长度；根据获得的SEM图，利用Nano Measurer粒径分布统计软件，选取多个(例如5个以上)测试区域进行直径的统计，每个测试区域的尺寸为0.5μm×0.5μm，之后取各个测试区域得到的直径的平均值作为构成三维骨架结构的材料的平均直径。
在一些实施例中，所述涂层中的所述三维骨架结构的含量可为6wt％至35wt％，可选为10wt％至30wt％，基于所述涂层的总重量计。三维骨架结构的含量在合适的范围内时，能够保证涂层浆料具有合适的粘度，更有利于涂布；此外，还有利于三维骨架结构与填料搭接形成一体化效果，由此能使涂层具有更稳定的空间网络结构，从而能够进一步提升隔离膜的离子导通性、对电解液的浸润和保持特性以及耐电压击穿能力。
二次电池在长期充放电过程中，由于正极活性材料和负极活性材料微观结构变化的不可逆，导致整个电池的体积会有所增大，特别地，当二次电池快速充电时，负极活性材料嵌入活性离子后的体积增大程度更高。电池膨胀后会对隔离膜产生挤压和/或拉伸作用，容易导致隔离膜破损，由此会增加正极和负极短路风险。因此，隔离膜还需要具有良好的耐外力挤压能力。填料中的至少一部分填充在三维骨架结构中，有助于涂层具有稳定的空间网络结构，由此能够提升隔离膜离子导通性和耐热性；此外，还能够提升隔离膜的拉伸强度、耐穿刺能力和耐外力挤压能力。
在一些实施例中，所述填料可包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒中的至少一种，可选地，所述填料包括二次颗粒形貌的填料颗粒，进一步可选地，所述填料同时包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒。二次颗粒形貌的填料颗粒具有比表面积大、与三维骨架结构亲和性好的优势，由此能够与三维骨架结构更好地搭接在一起，使涂层具有更稳定的空间网络结构，从而既能增加隔离膜的离子导通通道、促进离子传输，又能提升隔离膜的耐热性和对电解液的浸润和保持特性，由此采用本申请的隔离膜的二次电池能可具有长使用寿命和良好的倍率性能。一次颗粒形貌的填料颗粒的粒径较大，由此能够更好地发挥其在涂层中的支撑作用，减少二次颗粒形貌的填料颗粒的收缩，降低粘结剂用量，从而提升隔离膜的耐热性；一次颗粒形貌的填料颗粒的粒径较大，有助于在用量较少时使涂层具有更多的孔道结构和更少的水含量，进而能够进一步提升隔离膜的离子导通性以及对电解液的浸润和保持特性。
在一些实施例中，所述填料同时包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒，且所述二次颗粒形貌的填料颗粒与所述一次颗粒形貌的填料颗粒的质量比为2:1至27:1，可选为5:1至15:1。由此，有助于涂层具有稳定性更高和均一性更好的空间网络结构。
在一些实施例中，所述一次颗粒形貌的填料颗粒的平均粒径可为200nm至800nm，可选为200nm至400nm。由此能够更好地发挥一次颗粒形貌的填料颗粒的支撑作用，使涂层在长期充放电过程中保持稳定的孔道结构，进而有利于离子传输。
在一些实施例中，所述一次颗粒形貌的填料颗粒的BET比表面积可为≤10m 2/g，可选为3m 2/g至7m 2/g。由此能够更好地发挥一次颗粒形貌的填料颗粒的支撑作用，使涂层在长期充放电过程中保持稳定的孔道结构，进而有利于离子传输。
在一些实施例中，所述一次颗粒形貌的填料颗粒的含量可为≤30wt％，可选为5wt％至25wt％，基于所述涂层的总重量计。由此能够更好地发挥一次颗粒形貌的填料颗粒的支撑作用，使涂层在长期充放电过程中保持稳定的孔道结构，进而有利于离子传输。
在一些实施例中，所述二次颗粒形貌的填料颗粒的平均粒径可为≤200nm，可选为50nm至200nm。由此能使二次颗粒形貌的填料颗粒具有较高的比表面积，从而能够增加填料与三维骨架结构之间的亲和性，使填料与三维骨架结构能够更好地搭接在一起，从而涂层能具有更稳定的空间网络结构，进而隔离膜具有更好的耐热性、离子导通性和对电解液的浸润和保持特性。
在一些实施例中，所述二次颗粒形貌的填料颗粒的BET比表面积可为≥20m 2/g，可选为30m 2/g至80m 2/g。由此填料与三维骨架结构之间的亲和性更好，从而涂层能具有更稳定的空间网络结构，进而隔离膜具有更好的耐热性、离子导通性和对电解液的浸润和保持特性。
在一些实施例中，所述二次颗粒形貌的填料颗粒的含量可为≥60wt％，可选为70wt％至90wt％，基于所述涂层的总重量计。由此能够保证涂层浆料具有合适的粘度，更有利于涂布；此外，还有利于填料与三维骨架结构更好地搭接在一起，使涂层具有更稳定的空间网络结构，从而进一步提升隔离膜的拉伸强度、耐穿刺能力和耐外力挤压能力。
在一些实施例中，所述填料包括无机颗粒和有机颗粒中的至少一种。
在一些实施例中，无机颗粒可包括选自具有5或更高的介电常数的无机颗粒、具有传输活性离子能力的无机颗粒、能够发生电化学氧化和还原的无机颗粒中的至少一种。
在一些实施例中，具有5或更高的介电常数的无机颗粒可包括选自勃姆石(γ-AlOOH)、氧化铝(Al 2O 3)、硫酸钡(BaSO 4)、氧化镁(MgO)、氢氧化镁(Mg(OH) 2)、硅氧化合物SiO x(0＜x≤2)、二氧化锡(SnO 2)、氧化钛(TiO 2)、氧化钙(CaO)、氧化锌(ZnO)、氧化锆(ZrO 2)、氧化钇(Y 2O 3)、氧化镍(NiO)、二氧化铪(HfO 2)、氧化铈(CeO 2)、钛酸锆(ZrTiO 3)、钛酸钡(BaTiO 3)、氟化镁(MgF 2)、Pb(Zr,Ti)O 3(简写为PZT)、Pb 1-mLa mZr 1-nTi nO 3(简写为PLZT，0＜m＜1，0＜n＜1)和Pb(Mg 3Nb 2/3)O 3-PbTiO 3(简写为PMN-PT)中的至少一种。
在一些实施例中，具有传输活性离子能力的无机颗粒可包括选自磷酸锂(Li 3PO 4)、磷酸钛锂(Li xTi y(PO 4) 3，0＜x＜2，0＜y＜3)、磷酸钛铝锂(Li xAl yTi z(PO 4) 3，0＜x＜2，0＜y＜1，0＜z＜3)、(LiAlTiP) xO y类玻璃(0＜x＜4，0＜y＜13)、钛酸镧锂(Li xLa yTiO 3，0＜x＜2，0＜y＜3)、硫代磷酸锗锂(Li xGe yP zS w，0＜x＜4，0＜y＜1，0＜z＜1，0＜w＜5)、氮化锂(Li xN y，0＜x＜4，0＜y＜2)、SiS 2类玻璃(Li xSi yS z，0＜x＜3，0＜y＜2，0＜z＜4)和P 2S 5类玻璃(Li xP yS z，0＜x＜3，0＜y＜3，0＜z＜7)中的至少一种。
在一些实施例中，能够发生电化学氧化和还原的无机颗粒可包括选自含锂过渡金属氧化物、橄榄石结构的含锂磷酸盐、碳基材料、硅基材料、锡基材料和锂钛化合物中的至少一种。
在一些实施例中，有机颗粒可包括选自聚苯乙烯、聚乙烯、聚酰亚胺、三聚氰胺树脂、酚醛树脂、聚丙烯、聚酯(例如聚对苯二甲酸乙二酯、聚萘二甲酸乙二酯、聚对苯二甲酸丁二酯)、聚苯硫醚、聚芳酰胺、聚酰胺酰亚胺、聚酰亚胺、丙烯酸丁酯与甲基丙烯酸乙酯的共聚物及其混合物中的至少一种。
在一些实施例中，所述三维骨架结构与所述填料的质量比可为1:2至1:15.5，可选为1:5至1:10。由此有助于涂层具有合适的Zeta电位，从而能进一步提升涂层面密度和厚度的均一性以及孔隙的均匀性，从而能够进一步提升隔离膜的离子导通性以及二次电池的能量密度和循环性能。
在一些实施例中，所述涂层还可包括非颗粒状的粘结剂。本申请对非颗粒状的粘结剂的种类没有特别的限制，可以选用任意公知的具有良好粘结性的材料。可选地，所述非颗粒状的粘结剂包括水溶液型粘结剂，其具有热力学稳定性好且环保的优势，由此有利于涂层浆料的制备和涂布。作为示例，所述水溶液型粘结剂可包括水溶液型丙烯酸类树脂(例如，丙烯酸、甲基丙烯酸、丙烯酸钠单体均聚物或与其他共聚单体共聚物)、聚乙烯醇(PVA)、异丁烯-马来酸酐共聚物和聚丙烯酰胺中的至少一种。
可选地，所述涂层中的所述非颗粒状的粘结剂的含量为≤2wt％，基于所述涂层的总重量计。本申请的涂层中的三维骨架结构与填料能够搭接在一起使涂层具有稳定的空间网络结构，由此能够在减少粘结剂用量的前提下使隔离膜还能保持高粘结性。
在一些实施例中，所述涂层的厚度可为≤1μm，可选为0.5μm至0.8μm。由此有助于提升二次电池的能量密度。在本申请中，涂层的厚度是指位于多孔基材单侧的涂层的厚度。
在一些实施例中，所述多孔基材的厚度可为≤6μm，可选为3μm至5μm。本申请的涂层能使隔离膜的耐热性得到显著提升，由此可以选用更薄的多孔基材，从而有助于提升二次电池的能量密度。
本申请对多孔基材的材质没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的基材，例如，所述多孔基材可包括多孔聚烯烃基树脂膜(例如聚乙烯、聚丙烯、聚偏氟乙烯中的至少一种)、多孔玻璃纤维和多孔无纺布中的至少一种。所述多孔基材可以是单层薄膜，也可以是多层复合薄膜。所述多孔基材为多层复合薄膜时，各层的材料可以相同，也可以不同。
在一些实施例中，所述隔离膜还可包括粘接层，所述粘接层设置在所述涂层的至少一部分表面上，所述粘接层包括颗粒状的粘结剂。粘接层不仅能够防止涂层脱落，提高涂层与多孔基材的粘结性和二次电池的安全性能，而且能够改善隔离膜与电极的界面，提升二次电池的循环性能。
可选地，所述颗粒状的粘结剂包括丙烯酸酯类单体均聚物或共聚物、丙烯酸类单体均聚物或共聚物、含氟烯烃单体均聚物或共聚物中的至少一种。所述共聚单体包括但不限于如下中的至少一种：丙烯酸酯类单体、丙烯酸类单体、烯烃单体、含卤素烯烃单体、氟醚类单体等。
可选地，所述颗粒状的粘结剂包括偏二氟乙烯基聚合物，例如偏二氟乙烯单体(VDF)的均聚物和/或偏二氟乙烯单体与共聚单体的共聚物。所述共聚单体可为烯烃单体、含氟烯烃单体、含氯烯烃单体、丙烯酸酯类单体、丙烯酸类单体、氟醚类单体中的 至少一种。可选地，所述共聚单体可包括如下中的至少一种：三氟乙烯(VF3)、三氟氯乙烯(CTFE)、1,2-二氟乙烯、四氟乙烯(TFE)、六氟丙烯(HFP)、全氟(烷基乙烯基)醚(例如全氟(甲基乙烯基)醚PMVE、全氟(乙基乙烯基)醚PEVE、全氟(丙基乙烯基)醚PPVE)、全氟(1,3-间二氧杂环戊烯)和全氟(2,2-二甲基-1,3-间二氧杂环戊烯)(PDD)。
在一些实施例中，隔离膜在150℃、1h下的纵向热收缩率为≤5％，可选为0.5％至3％。
在一些实施例中，隔离膜在150℃、1h下的横向热收缩率为≤5％，可选为0.5％至3％。
本申请的隔离膜在150℃的高温下，横向和纵向两个方向均具有低热收缩率，由此能够提升二次电池的安全性能。
在一些实施例中，隔离膜的纵向拉伸强度为≥2000kg/cm 2，可选为2500kg/cm 2至4500kg/cm 2。
在一些实施例中，隔离膜的横向拉伸强度为≥2000kg/cm 2，可选为2500kg/cm 2至4500kg/cm 2。
本申请的隔离膜在横向和纵向两个方向均具有高拉伸强度，由此在二次电池膨胀时，隔离膜出现破损的概率较小，从而能够提升二次电池的安全性能。
在一些实施例中，隔离膜的润湿长度为≥30mm，可选为30mm至80mm。
在一些实施例中，隔离膜的润湿速度为≥3mm/s，可选为3mm/s至10mm/s。
本申请的隔离膜对电解液具有良好的浸润和保持特性，由此能够提升隔离膜的离子导通性和二次电池容量发挥特性。
在一些实施例中，隔离膜的透气度为≤300s/100mL，可选为100s/100mL至230s/100mL。本申请的隔离膜具有良好的透气度，由此能够提升离子导通性和二次电池容量发挥特性。
在本申请中，材料的平均粒径为本领域公知的含义，可采用本领域已知的仪器及方法进行测定。例如可以通过扫描电子显微镜、透射电子显微镜、颗粒尺寸分布仪器对材料或隔离膜进行测定获得图片，从图片上随机选取多个(例如10个以上)测试颗粒，统计颗粒最短对角线长度的平均值作为平均粒径。
在本申请中，材料的比表面积为本领域公知的含义，可采用本领域已知的仪器及方法进行测定。例如可以参照GB/T 19587-2017，采用氮气吸附比表面积分析测试方法测试，并用BET(Brunauer Emmett Teller)法计算得出。可选地，氮气吸附比表面积分析测试可以通过美国Micromeritics公司的Tri-Star 3020型比表面积孔径分析测试仪进行。
在本申请中，隔离膜的热收缩率、拉伸强度和透气度均具有本领域公知的含义，可以采用本领域已知的方法进行测量。例如，均可参照标准GB/T 36363-2018进行测试。
在本申请中，隔离膜的润湿长度、润湿速度均具有本领域公知的含义，可以采用本领域已知的方法进行测量。示例性测试方法如下：将隔离膜裁切成宽度为5mm、长度为100mm的样品，将样品两端固定后水平放置；取0.5mg电解液滴在样品中央，达到规定时间(本申请为1min)后，拍照并测量电解液扩散的长度，由此得到隔离膜的润湿长度和润湿速度。为了保证测试结果的准确性，可取多个(例如5至10个)样品进行测试，并且测试结果通过计算平均值得到。电解液可以按照如下方法配制：将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)按照质量比30:50:20进行混合得到有机溶剂，将充分干燥的LiPF 6溶解于上述有机溶剂中配制成浓度为1mol/L的电解液。
需要说明的是，上述隔离膜的涂层参数(例如厚度等)均为多孔基材单侧的涂层参数。当涂层设置在多孔基材的两侧时，其中任意一侧的涂层参数满足本申请，即认为落入本申请的保护范围内。
制备方法
本申请实施方式第二方面提供一种制备本申请实施方式第一方面的隔离膜的方法，包括以下步骤：S1，提供多孔基材；S2，配制涂层浆料，将用于构成三维骨架结构的材料和填料按照预定比例在溶剂中混合，配制成涂层浆料；S3，涂布，将所述涂层浆料涂布于所述多孔基材的至少一个表面上，形成涂层并干燥，获得隔离膜，其中，所述隔离膜包括多孔基材和设置在所述多孔基材的至少一个表面上的涂层，所述涂层包括三维骨架结构和填料，所述填料中的至少一部分填充在所述三维骨架结构中，并且所述涂层的Zeta电位为小于0mV。
在一些实施例中，在S2中，所述溶剂可以为水，例如去离子水。
在一些实施例中，在S2中，所述浆料还可以包括其他组分，例如，还可以包括分散剂、润湿剂、粘结剂等。
在一些实施例中，在S2中，构成所述三维骨架结构的材料包括纳米纤维素，所述纳米纤维素包括羟基和阴离子改性基团，所述阴离子改性基团包括胺基、羧基、磺酸基、硼酸基和磷酸基中的至少一种，可选包括磺酸基、硼酸基和磷酸基中的至少一种。
可选地，所述纳米纤维素为纤维素纳米晶须(Cellulose nanocrystals，CNC，又称为纤维素纳米晶、纳米晶体纤维素)。
在一些实施例中，在S2中，所述涂层浆料可通过以下方式获得：步骤1，配制纳米纤维素溶液，将具有阴离子改性基团的纳米纤维素与水混合配制成所述纳米纤维素溶液，其中，所述纳米纤维素溶液的pH在5至9之间、Zeta电位为小于0mV；步骤2，配制填料溶液，所述填料溶液的pH为≥7.5、Zeta电位为小于0mV；步骤3，混合，将所述纳米纤维素溶液和所述填料溶液按照预定比例混合，即得到涂层浆料，其中，所述涂层浆料的Zeta电位在-5mV以下。
在一些实施例中，在步骤1中，所述具有阴离子改性基团的纳米纤维素可通过以下方式获得：将纳米纤维素粉末与改性溶液混合并反应后，经过洗涤除杂，获得具有阴离子改性基团的纤维素纳米晶须，将所获得的具有阴离子改性基团的纤维素纳米晶须的pH调节至中性(例如pH在6.5至7.5之间)，并经研磨、切割获得具有阴离子改性基团的纳米纤维素。
在一些实施例中，所述纳米纤维素粉末的白度可为≥80％。所述纤维素粉末可以通过市购获得，或者采用化学法(例如酸解法、碱处理法、Tempo催化氧化法)、生物法(例如酶处理法)、机械法(例如超细研磨、超声破碎、高压均质)等获得。用于制备上述白度≥80％的纤维素粉末的纤维原料可以包括植物纤维，例如棉纤维(例如棉花纤维、木棉纤维)、麻纤维(例如剑麻纤维、苎麻纤维、黄麻纤维、亚麻纤维、大麻纤维、蕉麻纤维等)、棕纤维、木纤维、竹纤维、草纤维中的至少一种。
在一些实施例中，所述纤维素粉末也可通过以下方式制备获得：将纤维原料经过开松除渣后，用碱液(例如NaOH水溶液，其浓度可为4wt％至20wt％，可选为5wt％至15 wt％)蒸煮，然后再顺序经过水洗除杂(例如水洗次数为3次至6次)、漂白(例如可用次氯酸钠和/或双氧水)、酸洗除杂、水洗除杂、驱水、气流干燥，获得纤维素粉末。
在一些实施例中，所述改性溶液可为酸溶液(例如硫酸水溶液、硼酸水溶液、磷酸水溶液、醋酸水溶液)或碱溶液(例如尿素有机溶剂溶液)。可选地，所述改性溶液为酸溶液。
在一些实施例中，所述酸溶液的浓度可为5wt％至80wt％。
当改性溶液选用硫酸水溶液时，所述酸溶液的浓度可为40wt％至80wt％，由此可以获得具有磺酸基的纤维素粉末。当改性溶液选用硼酸水溶液时，所述酸溶液的浓度可为5wt％至10wt％，由此可以获得具有硼酸基的纤维素粉末。当改性溶液选用磷酸水溶液时，所述酸溶液的浓度可为45wt％至75wt％，由此可以获得具有磷酸基的纤维素粉末。当改性溶液选用醋酸水溶液时，所述酸溶液的浓度可为40wt％至80wt％，由此可以获得具有羧酸基的纤维素粉末。
可选地，所述尿素有机溶剂溶液为尿素二甲苯溶液，由此可以获得具有胺基的纤维素粉末。
在一些实施例中，所述纤维素粉末与所述改性溶液的质量比可为1:2.5至1:50，可选为1:5至1:30。
当改性溶液选用硫酸水溶液时，所述纤维素粉末与所述酸溶液的质量比可为1:5至1:30。当改性溶液选用硼酸水溶液时，所述纤维素粉末与所述酸溶液的质量比可为1:20至1:50。当改性溶液选用磷酸水溶液时，所述纤维素粉末与所述酸溶液的质量比可为1:5至1:30。当改性溶液选用醋酸水溶液时，所述纤维素粉末与所述酸溶液的质量比可为1:5至1:30。当改性溶液选用尿素有机溶剂溶液时，所述纤维素粉末与所述尿素有机溶剂溶液的质量比可为1:4至1:40。
在一些实施例中，当所述改性溶液为酸溶液时，所述反应可在不高于80℃的条件下进行，可选为在30℃至60℃的条件下进行，所述纤维素粉末与所述改性溶液的反应时间可为0.5h至4h，可选为1h至3h。
在一些实施例中，当所述改性溶液为碱溶液时，所述反应可在100℃至145℃的条件下进行，所述纤维素粉末与所述改性溶液的反应时间可为1h至5h。
在一些实施例中，研磨可以采用研磨机，切割可以采用高压均质机。通过调节研磨机的研磨参数(例如研磨次数、研磨时间等)以及高压均质机的切割参数能够获得具有不同平均直径和/或不同平均长度的纳米纤维素。
在一些实施例中，在步骤2中，所述填料溶液可通过以下方式获得：将填料、水与改性剂混合，获得pH为≥7.5、Zeta电位为小于0mV的填料溶液，所述改性剂包括选自碱、阴离子表面活性剂和非离子表面活性剂中的至少一种。
可选地，所述碱包括选自KOH、NaOH、NaHCO 3、LiOH、NH 4OH、Mg(OH) 2和Na 2CO 3中的至少一种。
可选地，所述阴离子表面活性剂包括选自磺酸盐型阴离子表面活性剂、羧酸盐型阴离子表面活性剂、硫酸酯盐型阴离子表面活性剂和磷酸酯盐型阴离子表面活性剂中的至少一种，进一步可选为包括选自烷基苯磺酸盐(例如丁基萘磺酸钠)、C12-C20烷基磺酸盐、聚丙烯酸钠、聚丙烯酸铵、羟乙基硫酸钠和C12-C20烷基硫酸钠中的至少一种。
可选地，所述非离子表面活性剂包括选自氟代烷基乙氧基醇醚和脂肪醇聚氧乙烯醚中的至少一种。
在一些实施例中，所述纳米纤维素溶液的浓度可为1wt％至10wt％，可选为2wt％至10wt％。
在一些实施例中，所述填料溶液的浓度可为30wt％至60wt％，可选为35wt％至55wt％。
在一些实施例中，在S2中，所述涂层浆料的pH可为5至10，可选为6至9。
在一些实施例中，在S2中，所述涂层浆料的静态粘度可在1000mpa.s以下。
由此可以有效减少涂层的膜面问题以及降低涂布不均匀出现的概率，从而进一步改善二次电池的能量密度和安全性能。
在一些实施例中，在S3中，所述涂布采用涂布机。本申请对涂布机的型号没有特殊限制，例如可以采用市购涂布机。所述涂布机包括凹版辊；所述凹版辊用于将浆料转移到多孔基材上。
在一些实施例中，在S3中，所述涂布方式可以采用转移涂布、旋转喷涂、浸涂等。
在一些实施例中，所述方法还包括以下步骤：S4，二次涂布，将包含颗粒状的粘结剂的浆料涂布于所述涂层的至少一部分表面上，干燥后形成粘接层。
本申请的隔离膜的制备方法通过一次涂布制得涂层，大大简化了隔离膜的生产工艺流程。
本申请的隔离膜的制备方法中使用的一些原料及其含量等参数可以参考本申请实施方式第一方面的隔离膜，此处不再赘述。
如果没有特别的说明，在本申请的隔离膜的制备方法中所使用的各原料均可以通过市购获得。
二次电池
本申请实施方式第三方面提供一种二次电池。
二次电池又称为充电电池或蓄电池，是指在电池放电后可通过充电的方式使活性材料激活而继续使用的电池。通常情况下，二次电池包括电极组件和电解液，所述电极组件包括正极极片、负极极片和隔离膜，所述隔离膜设置在所述正极极片和所述负极极片之间，主要起到防止正极和负极短路的作用，同时可以使活性离子通过。
本申请对二次电池种类没有特别的限制，例如，所述二次电池可以为锂离子电池、钠离子电池等，特别地，所述二次电池可以为锂离子二次电池。
本申请实施方式第三方面的二次电池包括本申请实施方式第一方面的隔离膜或通过本申请实施方式第二方面的方法制备的隔离膜，所述隔离膜间隔于所述正极极片和所述负极极片之间。可选地，至少所述隔离膜靠近所述负极极片的一侧具有本申请的涂层。由此，本申请的二次电池能兼顾高能量密度、高热安全性能和长使用寿命。
[正极极片]
在一些实施例中，所述正极极片包括正极集流体以及设置在所述正极集流体至少一个表面且包括正极活性材料的正极膜层。例如，所述正极集流体具有在自身厚度方向相对的两个表面，所述正极膜层设置在所述正极集流体的两个相对表面中的任意一者或两者上。
当本申请的二次电池为锂离子电池时，所述正极活性材料可包括但不限于含锂过渡金属氧化物、含锂磷酸盐及其各自的改性化合物中的至少一种。所述锂过渡金属氧化物的示例可包括但不限于锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物及其各自的改性化合物中的至少一种。所述含锂磷酸盐的示例可包括但不限于磷酸铁锂、磷酸铁锂与碳的复合材料、磷酸锰锂、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料及其各自的改性化合物中的至少一种。
在一些实施例中，为了进一步提高二次电池的能量密度，用于锂离子电池的正极活性材料可以包括通式为Li aNi bCo cM dO eA f的锂过渡金属氧化物及其改性化合物中的至少一种。0.8≤a≤1.2，0.5≤b＜1，0＜c＜1，0＜d＜1，1≤e≤2，0≤f≤1，M选自Mn、Al、Zr、Zn、Cu、Cr、Mg、Fe、V、Ti和B中的至少一种，A选自N、F、S和Cl中的至少一种。
作为示例，用于锂离子电池的正极活性材料可包括LiCoO 2、LiNiO 2、LiMnO 2、LiMn 2O 4、LiNi 1/3Co 1/3Mn 1/3O 2(NCM333)、LiNi 0.5Co 0.2Mn 0.3O 2(NCM523)、LiNi 0.6Co 0.2Mn 0.2O 2(NCM622)、LiNi 0.8Co 0.1Mn 0.1O 2(NCM811)、LiNi 0.85Co 0.15Al 0.05O 2、LiFePO 4、LiMnPO 4中的至少一种。
当本申请的二次电池为钠离子电池时，所述正极活性材料可包括但不限于含钠过渡金属氧化物、聚阴离子材料(如磷酸盐、氟磷酸盐、焦磷酸盐、硫酸盐等)、普鲁士蓝类材料中的至少一种。
作为示例，用于钠离子电池的正极活性材料可包括NaFeO 2、NaCoO 2、NaCrO 2、NaMnO 2、NaNiO 2、NaNi 1/2Ti 1/2O 2、NaNi 1/2Mn 1/2O 2、Na 2/3Fe 1/3Mn 2/3O 2、NaNi 1/3Co 1/3Mn 1/3O 2、NaFePO 4、NaMnPO 4、NaCoPO 4、普鲁士蓝类材料、通式为X pM’ q(PO 4) rO xY 3-x的材料中的至少一种。在通式X pM’ q(PO 4) rO xY 3-x中，0＜p≤4，0＜q≤2，1≤r≤3，0≤x≤2，X选自H +、Li +、Na +、K +和NH 4 +中的至少一种，M’为过渡金属阳离子，可选地为V、Ti、Mn、Fe、Co、Ni、Cu和Zn中的至少一种，Y为卤素阴离子，可选地为F、Cl和Br中的至少一种。
在本申请中，上述各正极活性材料的改性化合物可以是对所述正极活性材料进行掺杂改性和/或表面包覆改性。
在一些实施例中，所述正极膜层还可选地包括正极导电剂。本申请对所述正极导电剂的种类没有特别的限制，作为示例，所述正极导电剂包括超导碳、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的至少一种。在一些实施例中，基于所述正极膜层的总质量，所述正极导电剂的质量百分含量为≤5％。
在一些实施例中，所述正极膜层还可选地包括正极粘结剂。本申请对所述正极粘结剂的种类没有特别的限制，作为示例，所述正极粘结剂可包括聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物和含氟丙烯酸酯类树脂中的至少一种。在一些实施例中，基于所述正极膜层的总质量，所述正极粘结剂的质量百分含量为≤5％。
在一些实施例中，所述正极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铝箔。所述复合集流体可包括高分子材料基层以及形成于所述高分子材料基层至少一个表面上的金属材料层。作为示例，所述金属材料可包括铝、铝合金、镍、 镍合金、钛、钛合金、银和银合金中的至少一种。作为示例，所述高分子材料基层可包括聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)和聚乙烯(PE)中的至少一种。
所述正极膜层通常是将正极浆料涂布于正极集流体上，经干燥、冷压而成的。所述正极浆料通常是将正极活性材料、可选的导电剂、可选的粘结剂以及任意的其他组分分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)，但不限于此。
[负极极片]
在一些实施例中，所述负极极片包括负极集流体以及设置在所述负极集流体至少一个表面且包括负极活性材料的负极膜层。例如，所述负极集流体具有在自身厚度方向相对的两个表面，所述负极膜层设置在所述负极集流体的两个相对表面中的任意一者或两者上。
所述负极活性材料可采用本领域公知的用于二次电池的负极活性材料。作为示例，所述负极活性材料可包括但不限于天然石墨、人造石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂中的至少一种。所述硅基材料可包括单质硅、硅氧化物、硅碳复合物、硅氮复合物和硅合金材料中的至少一种。所述锡基材料可包括单质锡、锡氧化物和锡合金材料中的至少一种。
在一些实施例中，所述负极膜层还可选地包括负极导电剂。本申请对所述负极导电剂的种类没有特别的限制，作为示例，所述负极导电剂可包括超导碳、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的至少一种。在一些实施例中，基于所述负极膜层的总质量，所述负极导电剂的质量百分含量为≤5％。
在一些实施例中，所述负极膜层还可选地包括负极粘结剂。本申请对所述负极粘结剂的种类没有特别的限制，作为示例，所述负极粘结剂可包括丁苯橡胶(SBR)、水溶性不饱和树脂SR-1B、水性丙烯酸类树脂(例如，聚丙烯酸PAA、聚甲基丙烯酸PMAA、聚丙烯酸钠PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)和羧甲基壳聚糖(CMCS)中的至少一种。在一些实施例中，基于所述负极膜层的总质量，所述负极粘结剂的质量百分含量为≤5％。
在一些实施例中，所述负极膜层还可选地包括其他助剂。作为示例，其他助剂可包括增稠剂，例如，羧甲基纤维素钠(CMC)、PTC热敏电阻材料等。在一些实施例中，基于所述负极膜层的总质量，所述其他助剂的质量百分含量为≤2％。
在一些实施例中，所述负极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铜箔。所述复合集流体可包括高分子材料基层以及形成于所述高分子材料基层至少一个表面上的金属材料层。作为示例，所述金属材料可包括铜、铜合金、镍、镍合金、钛、钛合金、银和银合金中的至少一种。作为示例，所述高分子材料基层可包括聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)和聚乙烯(PE)中的至少一种。
所述负极膜层通常是将负极浆料涂布于负极集流体上，经干燥、冷压而成的。所述负极浆料通常是将负极活性材料、可选的导电剂、可选地粘结剂、其他可选的助剂分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水，但不限于此。
所述负极极片并不排除除了所述负极膜层之外的其他附加功能层。例如在某些实施例中，本申请所述的负极极片还包括夹在所述负极集流体和所述负极膜层之间、设置在所述负极集流体表面的导电底涂层(例如由导电剂和粘结剂组成)。在另外一些实施例中，本申请所述的负极极片还包括覆盖在所述负极膜层表面的保护层。
[电解液]
在二次电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出，电解液在正极极片和负极极片之间起到传导活性离子的作用。本申请对电解液的种类没有特别的限制，可根据实际需求进行选择。
所述电解液包括电解质盐和溶剂。所述电解质盐和所述溶剂的种类不受具体的限制，可根据实际需求进行选择。
当本申请的二次电池为锂离子电池时，作为示例，所述电解质盐可包括但不限于六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)和四氟草酸磷酸锂(LiTFOP)中的至少一种。
当本申请的二次电池为钠离子电池时，作为示例，所述电解质盐可包括但不限于六氟磷酸钠(NaPF 6)、四氟硼酸钠(NaBF 4)、高氯酸钠(NaClO 4)、六氟砷酸钠(NaAsF 6)、双氟磺酰亚胺钠(NaFSI)、双三氟甲磺酰亚胺钠(NaTFSI)、三氟甲磺酸钠(NaTFS)、二氟草酸硼酸钠(NaDFOB)、二草酸硼酸钠(NaBOB)、二氟磷酸钠(NaPO 2F 2)、二氟二草酸磷酸钠(NaDFOP)和四氟草酸磷酸钠(NaTFOP)中的至少一种。
作为示例，所述溶剂可包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸乙烯酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)和二乙砜(ESE)中的至少一种。
在一些实施例中，所述电解液中还可选地包括添加剂。例如，所述添加剂可以包括负极成膜添加剂，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温功率性能的添加剂等。
在一些实施例中，所述正极极片、所述隔离膜和所述负极极片可通过卷绕工艺和/或叠片工艺制成电极组件。
在一些实施例中，所述二次电池可包括外包装。该外包装可用于封装上述电极组件及电解液。
在一些实施例中，所述二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。所述二次电池的外包装也可以是软包，例如袋式软包。所述软包的材质可以是塑料， 如聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)和聚丁二酸丁二醇酯(PBS)中的至少一种。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图1是作为一个示例的方形结构的二次电池5。
在一些实施例中，如图2所示，外包装可包括壳体51和盖板53。壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53用于盖设所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺和/或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，可根据需求来调节。
本申请的二次电池的制备方法是公知的。在一些实施例中，可将正极极片、隔离膜、负极极片和电解液组装形成二次电池。作为示例，可将正极极片、隔离膜、负极极片经卷绕工艺和/或叠片工艺形成电极组件，将电极组件置于外包装中，烘干后注入电解液，经过真空封装、静置、化成、整形等工序，得到二次电池。
在本申请的一些实施例中，根据本申请的二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图3是作为一个示例的电池模块4的示意图。如图3所示，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施例中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图4和图5是作为一个示例的电池包1的示意图。如图4和图5所示，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2用于盖设下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
用电装置
本申请实施方式第四方面提供一种用电装置，所述用电装置包括本申请的二次电池、电池模块或电池包中的至少一种。所述二次电池、电池模块或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
所述用电装置可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置的示意图。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该用电装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
下述实施例更具体地描述了本申请公开的内容，这些实施例仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施例中所报道的所有份、百分比和比值都是基于质量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
改性纳米纤维素C1的制备
纤维素粉末制备
将棉花短绒通过开棉机开松除渣后，使用5wt％的NaOH水溶液在150℃蒸煮2h，然后再顺序经过水洗除杂(水洗次数为3次)、次氯酸钠漂白、稀盐酸洗涤除杂、水洗除杂(水洗次数为1次)、驱水、气流干燥后，获得白度为≥85％的棉花纤维素粉末。
纤维素的酯化
将所获得的棉花纤维素粉末1kg与60wt％的硫酸水溶液30kg混合，在60℃下反应1.5h，反应结束后，再顺序经过水洗除杂(水洗次数为3次)、过滤、除酸除杂，获得具有磺酸基的纤维素纳米晶须。
纤维素的中和
用10wt％的NaOH水溶液先将具有磺酸基的纤维素纳米晶须的pH调至中性，然后用研磨机高速处理2.5h将其分散，研磨次数为2次，再使用高压均质机设备进行纳米级切割，得到平均长度为400nm、平均直径为25nm的具有磺酸基改性基团的纳米纤维素C1，并且磺酸基与羟基的摩尔比为5:3。
改性纳米纤维素C2至C4的制备
改性纳米纤维素C2至C4按照与改性纳米纤维素C1类似的方法制备，不同之处详见表1。在制备过程中，可以通过调节研磨机处理的参数以及高压均质机设备的切割参数获得具有不同平均直径和/或不同平均长度的改性纳米纤维素。
改性纳米纤维素C5的制备
纤维素粉末制备
将棉花短绒通过开棉机开松除渣后，使用5wt％的NaOH水溶液在150℃蒸煮2h，然后再顺序经过水洗除杂(水洗次数为3次)、次氯酸钠漂白、稀盐酸洗涤除杂、水洗除杂(水洗次数为1次)、驱水、气流干燥后，获得白度为≥85％的棉花纤维素粉末。在10℃条件下，将获得的棉花纤维素粉末与20wt％的NaOH水溶液混合，搅拌2h、过滤、水洗2次后，获得纤维素粉末。
纤维素的酯化
将所获得的纤维素粉末50g与尿素200g置于带油水分离器的三口反应器中，待尿素溶解后，再加入5g二甲苯，搅拌下升温至137℃，反应4h后终止，然后经过水洗(水洗次数为3次)、过滤、干燥，获得纤维素氨基甲酸酯。
纤维素的中和
将所获得的纤维素氨基甲酸酯溶解在5wt％的NaOH水溶液中，得到均匀的纤维素氨基甲酸酯溶液，然后用研磨机高速处理2.5h将其分散，研磨次数为2次，再使用高压均质机设备进行纳米级切割，得到平均长度为400nm、平均直径为25nm的具有胺基改性 基团的纳米纤维素，并且胺基与与羟基的摩尔比为4:3。
阴离子改性基团与羟基的摩尔比可以通过以下方法测得：依据GB/T 12008.3-2009中的邻苯二甲酸酐法分别测试得到原料纤维素和改性纳米纤维素的羟值(与每克试样中羟基含量相当的氢氧化钾毫克数)，得到的数值单位为mg KOH/g，将其转化为mmol/g，作为羟基含量。以原料纤维素的羟基含量减去改性纳米纤维素的羟基含量，即可得阴离子改性基团的含量(即被改性的羟基的含量)，由此计算得到阴离子改性基团与羟基的摩尔比。
纳米纤维素C6的制备
采用未改性纳米纤维素，平均长度为400nm、平均直径为25nm。产品型号为CNWS-50，购自中科雷鸣(北京)科技有限公司，可以使用研磨机和/或高压均质机进一步处理，以获得具有不同平均直径和/或不同平均长度的纳米纤维素。
表1
Figure PCTCN2022112582-appb-000001
实施例1
(1)隔离膜的制备
S1，提供PE多孔基材
PE多孔基材厚度为5μm，孔隙率为40％。
S2，配制涂层浆料
步骤1，将10g改性纳米纤维素C1与190g溶剂水混合均匀配制成pH为7.5、Zeta电位为-35.7mV的纳米纤维素溶液；步骤2，向102g固含量为50wt％的氧化铝分散液(二次颗粒形貌，平均粒径为180nm)中加入6.6g浓度为10wt％的NaOH水溶液混合均匀配制成pH为9.5、Zeta电位为-10.1mV的填料溶液；步骤3，将所配制的纳米纤维素溶液和所配制的填料溶液按照溶液质量比10:3混合均匀形成混合液，然后在混合液中加入1wt％粘结剂水溶液型聚丙烯酸(基于干燥后的涂层的总重量计)，即得到涂层浆料。
S3，涂布
将所配制的涂层浆料用涂布机涂布于PE多孔基材的两个表面上，通过干燥、分切工序，得到隔离膜。位于PE多孔基材单侧的涂层的厚度为0.8μm。
(2)正极极片的制备
将正极活性材料LiNi 0.8Co 0.1Mn 0.1O 2(NCM811)、导电剂炭黑(Super P)、粘结剂聚偏二氟乙烯(PVDF)按照质量比96.2:2.7:1.1在适量的溶剂N-甲基吡咯烷酮(NMP)中混合均匀，得到正极浆料；将正极浆料涂布于正极集流体铝箔上，通过烘干、冷压、分条、裁切等工序，得到正极极片。正极极片的面密度为0.207mg/mm 2，压实密度为3.5g/cm 3。
(3)负极极片的制备
将负极活性材料人造石墨、导电剂炭黑(Super P)、粘结剂丁苯橡胶(SBR)和羧甲基纤维素钠(CMC)按照质量比96.4:0.7:1.8:1.1在适量的溶剂去离子水中混合均匀，得到负极浆料；将负极浆料涂布于负极集流体铜箔上，通过烘干、冷压、分条、裁切工序，得到负极极片。负极极片的面密度为0.126mg/mm 2，压实密度为1.7g/cm 3。
(4)电解液的制备
将碳酸乙烯酯(EC)和碳酸甲乙酯(EMC)按照质量比30:70进行混合得到有机溶剂，将充分干燥的LiPF 6溶解于上述有机溶剂中配制成浓度为1mol/L的电解液。
(5)二次电池的制备
将正极极片、隔离膜、负极极片按顺序堆叠并卷绕，得到电极组件；将电极组件置于外包装中，干燥后注入电解液，经过真空封装、静置、化成、整形等工序，得到二次电池。
实施例2-9
二次电池采用与实施例1类似的方法制备，不同之处在于隔离膜的制备中，涂层浆料的制备参数不同，具体详见表2。
实施例10
二次电池采用与实施例1类似的方法制备，不同之处在于隔离膜的制备中，配制涂层浆料时还加入了一次颗粒形貌的氧化铝，具体参数详见表2。
步骤1，将10g改性纳米纤维素C1与190g溶剂水混合均匀配制成pH为7.5、Zeta电位为-35.7mV的纳米纤维素溶液；步骤2，向102g固含量为50wt％的氧化铝分散液(二次颗粒形貌和一次颗粒形貌的混合，质量比为5:1，二次颗粒的平均粒径为180nm，一次颗粒的平均粒径为400nm)中加入6.6g浓度为10wt％的NaOH水溶液混合均匀配制成pH为9.5、Zeta电位为-10.1mV的填料溶液；步骤3，将所配制的纳米纤维素溶液和所配制的填料溶液按照溶液质量比10:3混合均匀形成混合液，然后在混合液中加入1wt％粘结剂水溶液型聚丙烯酸(基于干燥后的涂层的总重量计)，即得到涂层浆料。
对比例1
二次电池采用与实施例1类似的方法制备，不同之处在于隔离膜的制备中，配制涂层浆料时采用未改性纳米纤维素C6以及采用未改性的一次颗粒形貌的氧化铝，具体参数详见表2。
步骤1，将10g未改性纳米纤维素C6与190g溶剂水混合均匀配制成pH为8.6、Zeta电位为20.5mV的纳米纤维素溶液；步骤2，将102g固含量为50wt％的氧化铝分散液(一次颗粒形貌，一次颗粒的平均粒径为800nm)作为填料溶液，其pH为7.4、Zeta电位为-5.5mV；步骤3，将所配制的纳米纤维素溶液和所配制的填料溶液按照溶液质量比10:3混合均匀形成混合液，然后在混合液中加入1wt％粘结剂水溶液型聚丙烯酸(基于干燥后的涂层的总重量计)，即得到涂层浆料。
对比例2
二次电池采用与实施例1类似的方法制备，不同之处在于隔离膜的制备中，配制涂层浆料时采用未改性纳米纤维素C6以及采用未改性的二次颗粒形貌的氧化铝，具体参数详见表2。
步骤1，将10g未改性纳米纤维素C6与190g溶剂水混合均匀配制成pH为8.6、Zeta 电位为20.5mV的纳米纤维素溶液；步骤2，将102g固含量为50wt％的氧化铝分散液(二次颗粒形貌，二次颗粒的平均粒径为180nm)作为填料溶液，其pH为5.6、Zeta电位为39.3mV；步骤3，将所配制的纳米纤维素溶液和所配制的填料溶液按照溶液质量比10:3混合均匀形成混合液，然后在混合液中加入1wt％粘结剂水溶液型聚丙烯酸(基于干燥后的涂层的总重量计)，即得到涂层浆料。
对比例3
二次电池采用与实施例1类似的方法制备，不同之处在于隔离膜的制备中，配制涂层浆料时采用未改性纳米纤维素C6，具体参数详见表2。
步骤1，将10g未改性纳米纤维素C6与190g溶剂水混合均匀配制成pH为8.6、Zeta电位为20.5mV的纳米纤维素溶液；步骤2，向102g固含量为50wt％的氧化铝分散液(二次颗粒形貌，平均粒径为180nm)中加入6.6g浓度为10wt％的NaOH水溶液混合均匀配制成pH为9.5、Zeta电位为-10.1mV的填料溶液；步骤3，将所配制的纳米纤维素溶液和所配制的填料溶液按照溶液质量比10:3混合均匀形成混合液，然后在混合液中加入1wt％粘结剂水溶液型聚丙烯酸(基于干燥后的涂层的总重量计)，即得到涂层浆料。
对比例4
二次电池采用与实施例1类似的方法制备，不同之处在于隔离膜的制备中，配制涂层浆料时采用未改性的二次颗粒形貌的氧化铝，具体参数详见表2。
步骤1，将10g改性纳米纤维素C1与190g溶剂水混合均匀配制成pH为7.5、Zeta电位为-35.7mV的纳米纤维素溶液；步骤2，将102g固含量为50wt％的氧化铝分散液(二次颗粒形貌，二次颗粒的平均粒径为180nm)作为填料溶液，其pH为5.6、Zeta电位为39.3mV；步骤3，将所配制的纳米纤维素溶液和所配制的填料溶液按照溶液质量比10:3混合均匀形成混合液，然后在混合液中加入1wt％粘结剂水溶液型聚丙烯酸(基于干燥后的涂层的总重量计)，即得到涂层浆料。
测试部分
(1)涂层的Zeta电位测试
使用刀片从制备的隔离膜中刮取30g涂层材料粉末(刮粉深度不超过涂层与多孔基材之间的分界区)，然后将其与2000g去离子水使用带齿盘的搅拌器在一定搅拌速度下(例如可以为2000r/min)搅拌后得到分散液(搅拌时间例如可以为1.5小时)，将所获得的分散液置于样品池中，然后使用Zeta电位仪进行测试获得分散液的Zeta电位，即为涂层的Zeta电位。样品池可以采用马尔文公司的DTS1070 Zeta电位毛细管样品池，Zeta电位仪可以采用马尔文公司的Zetasizer Advance纳米粒度电位仪。
测试标准可参考GB/T 32671.2-2019和ISO 13099-2-2012。为了准确性，可以取5个平行样品进行测试然后取平均值作为测试结果。
(2)纳米纤维素溶液、填料溶液和涂层浆料的Zeta电位测试
将上述各溶液分别置于样品池中，然后使用Zeta电位仪进行测试获得各溶液的Zeta电位。样品池可以采用马尔文公司的DTS1070 Zeta电位毛细管样品池，Zeta电位仪可以采用马尔文公司的Zetasizer Advance纳米粒度电位仪。测试标准可参考GB/T 32671.2-2019和ISO 13099-2-2012。为了准确性，可以取5个平行样品进行测试然后取平均值作为测试结果。
(3)隔离膜的热收缩率测试
样品制备：将上述制备的隔离膜用冲压机冲切成宽度为50mm、长度为100mm的样品，取5个平行样品放置在A4纸上并固定，再将装有样品的A4纸放置在厚度为1mm至5mm的瓦楞纸上。
样品测试：将鼓风式烘箱温度设置为150℃，待温度达到设定温度并稳定30min后，开始计时，将放置在瓦楞纸上面的A4纸放入鼓风式烘箱，到达设定时间(本申请为1h)后，测量隔离膜的长度和宽度，数值分别标记为a和b。
热收缩率计算：纵向(MD)热收缩率＝[(100-a)/100]×100％，横向(TD)热收缩率＝[(50-b)/50]×100％，取5个平行样品的平均值作为测试结果。
(4)隔离膜的透气度测试
在25℃下，测定100mL空气通过隔离膜所需要的时间，为了准确性，取5个平行样品的平均值作为测试结果。测试仪器可以采用熊谷KRK王研式透气度测试仪。
(5)二次电池的循环性能测试
在25℃下，将二次电池以1C恒流充电至4.2V，继续恒压充电至电流为≤0.05C，此时二次电池为满充状态，记录此时的充电容量，即为第1圈充电容量；将二次电池静置5min后，以1C恒流放电至2.8V，此为一个循环充放电过程，记录此时的放电容量，即为第1圈放电容量。将二次电池按照上述方法进行循环充放电测试，记录每圈循环后的放电容量。二次电池25℃循环500圈容量保持率(％)＝500圈循环后的放电容量/第1圈放电容量×100％。为了准确性，取5个平行样品的平均值作为测试结果。
(6)二次电池的热箱测试
在25℃下，将二次电池以1C恒流充电至4.2V，继续恒压充电至电流为≤0.05C，静置5min；然后在DHG-9070A DHG系列高温烘箱中带夹具测试各二次电池，以5℃/min的速率从室温升至80±2℃，保持30min；之后再以5℃/min升温速度升温，每升温5℃，保温30min。升温过程中监控二次电池表面温度变化，当温度开始急剧上升时对应的烘箱温度即为二次电池的热箱失效温度。二次电池的热箱失效温度越高，表明二次电池的热安全性能越好。为了准确性，取5个平行样品的平均值作为测试结果。
由表2和表3可见，实施例1至实施例10通过在多孔基材的两个表面设置包含纳米纤维素(构成三维骨架结构)和填料的涂层，并调节涂层的Zeta电位为小于0mV，能够使所获得的隔离膜兼顾低热收缩率和高透气度，所获得的二次电池能够兼顾高热安全性能和良好的循环性能。发明人推测可能的原因在于，涂层的Zeta电位在合适的范围内时，涂层浆料具有良好的分散性，由此涂层浆料干燥后可形成面密度和厚度均一性好的涂层，提升了隔离膜的耐热性，同时涂层孔隙分布均匀，可确保涂层离子导通性好，从而可以使二次电池兼顾高热安全性能和良好的循环性能。
对比例1至对比例4制备的隔离膜的涂层均不满足Zeta电位为小于0mV，进而隔离膜不能兼顾低热收缩率和高透气度，二次电池也不能够兼顾高热安全性能和良好的循环性能。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领 域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。
Figure PCTCN2022112582-appb-000002
Figure PCTCN2022112582-appb-000003

Claims (26)

  1. 一种隔离膜，包括多孔基材和设置在所述多孔基材的至少一个表面上的涂层，其中，所述涂层包括三维骨架结构和填料，所述填料中的至少一部分填充在所述三维骨架结构中，并且所述涂层的Zeta电位为小于0mV，
    所述涂层的Zeta电位通过如下方法测试得到：取30g涂层材料粉末与2000g去离子水搅拌混合后得到分散液，通过Zeta电位仪测试所获得的分散液的Zeta电位，即为所述涂层的Zeta电位。
  2. 根据权利要求1所述的隔离膜，其中，所述涂层的Zeta电位为-50mV至-5mV，可选为-25mV至-5mV。
  3. 根据权利要求1或2所述的隔离膜，其中，构成所述三维骨架结构的材料包括有机棒状物和有机管状物中的至少一种；
    可选地，构成所述三维骨架结构的材料包括纳米纤维素、聚四氟乙烯纳米纤维和聚酰胺纳米纤维中的至少一种，
    可选地，所述纳米纤维素包括纤维素纳米纤维、纤维素纳米晶须和细菌纳米纤维素中的至少一种。
  4. 根据权利要求1-3任一项所述的隔离膜，其中，构成所述三维骨架结构的材料包括纳米纤维素，所述纳米纤维素包括羟基和阴离子改性基团，可选地，所述阴离子改性基团包括胺基、羧基、磺酸基、硼酸基和磷酸基中的至少一种，更可选包括磺酸基、硼酸基和磷酸基中的至少一种。
  5. 根据权利要4所述的隔离膜，其中，所述阴离子改性基团与所述羟基的摩尔比为1:4至4:1，可选为2:3至7:3。
  6. 根据权利要求1-5任一项所述的隔离膜，其中，构成所述三维骨架结构的材料的平均直径为≤40nm，可选为10nm至35nm。
  7. 根据权利要求1-6任一项所述的隔离膜，其中，
    构成所述三维骨架结构的材料的平均长度为100nm至600nm，可选为200nm至400nm；和/或，
    构成所述三维骨架结构的材料的长径比为5至60，可选为15至30。
  8. 根据权利要求1-7任一项所述的隔离膜，其中，所述填料包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒中的至少一种；
    可选地，所述填料包括二次颗粒形貌的填料颗粒；
    进一步可选地，所述填料同时包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒。
  9. 根据权利要求8所述的隔离膜，其中，所述一次颗粒形貌的填料颗粒满足如下条件(1)至(3)中的至少一者：
    (1)所述一次颗粒形貌的填料颗粒的平均粒径为200nm至800nm，可选为200nm至400nm；
    (2)所述一次颗粒形貌的填料颗粒的BET比表面积为≤10m 2/g，可选为3m 2/g至7m 2/g；
    (3)所述一次颗粒形貌的填料颗粒的含量为≤30wt％，可选为5wt％至25wt％，基于所述涂层的总重量计。
  10. 根据权利要求8或9所述的隔离膜，其中，所述二次颗粒形貌的填料颗粒满足如下条件(1)至(3)中的至少一者：
    (1)所述二次颗粒形貌的填料颗粒的平均粒径为≤200nm，可选为50nm至200nm；
    (2)所述二次颗粒形貌的填料颗粒的BET比表面积为≥20m 2/g，可选为30m 2/g至80m 2/g；
    (3)所述二次颗粒形貌的填料颗粒的含量为≥60wt％，可选为70wt％至90wt％，基于所述涂层的总重量计。
  11. 根据权利要求1-10任一项所述的隔离膜，其中，所述填料同时包括一次颗粒形貌的填料颗粒和二次颗粒形貌的填料颗粒，且所述二次颗粒形貌的填料颗粒与所述一次颗粒形貌的填料颗粒的质量比为2:1至27:1，可选为5:1至15:1。
  12. 根据权利要求1-11任一项所述的隔离膜，其中，所述填料包括无机颗粒和有机颗粒中的至少一种；
    可选地，所述无机颗粒包括选自具有5或更高的介电常数的无机颗粒、具有传输活性离子能力的无机颗粒、能够发生电化学氧化和还原的无机颗粒中的至少一种；
    可选地，所述有机颗粒包括选自聚苯乙烯、聚乙烯、聚酰亚胺、三聚氰胺树脂、酚醛树脂、聚丙烯、聚酯、聚苯硫醚、聚芳酰胺、聚酰胺酰亚胺、聚酰亚胺、丙烯酸丁酯与甲基丙烯酸乙酯的共聚物及其混合物中的至少一种。
  13. 根据权利要求1-12任一项所述的隔离膜，其中，
    所述涂层中的所述三维骨架结构的含量为6wt％至35wt％，可选为10wt％至30wt％，基于所述涂层的总重量计；和/或，
    所述三维骨架结构与所述填料的质量比为1:2至1:15.5，可选为1:5至1:10。
  14. 根据权利要求1-13任一项所述的隔离膜，其中，所述涂层还包括非颗粒状的粘结剂，
    可选地，所述非颗粒状的粘结剂包括水溶液型粘结剂；
    可选地，所述涂层中的所述非颗粒状的粘结剂的含量为≤2wt％，基于所述涂层的总重量计。
  15. 根据权利要求1-14任一项所述的隔离膜，其中，
    所述多孔基材的厚度为≤6μm，可选为3μm至5μm；和/或，
    所述涂层的厚度为≤1μm，可选为0.5μm至0.8μm。
  16. 根据权利要求1-15任一项所述的隔离膜，其中，所述隔离膜还包括粘接层，所述粘接层设置在所述涂层的至少一部分表面上，所述粘接层包括颗粒状的粘结剂；
    可选地，所述颗粒状的粘结剂包括丙烯酸酯类单体均聚物或共聚物、丙烯酸类单体均聚物或共聚物、含氟烯烃单体均聚物或共聚物中的至少一种。
  17. 根据权利要求1-16任一项所述的隔离膜，其中，所述隔离膜满足如下条件(1)至(7)中的至少一者：
    (1)所述隔离膜在150℃、1h下的纵向热收缩率为≤5％，可选为0.5％至3％；
    (2)所述隔离膜在150℃、1h下的横向热收缩率为≤5％，可选为0.5％至3％；
    (3)所述隔离膜的纵向拉伸强度为≥2000kg/cm 2，可选为2500kg/cm 2至4500kg/cm 2；
    (4)所述隔离膜的横向拉伸强度为≥2000kg/cm 2，可选为2500kg/cm 2至4500kg/cm 2；
    (5)所述隔离膜的润湿长度为≥30mm，可选为30mm至80mm；
    (6)所述隔离膜的润湿速度为≥3mm/s，可选为3mm/s至10mm/s；
    (7)所述隔离膜的透气度为≤300s/100mL，可选为100s/100mL至230s/100mL。
  18. 一种制备权利要求1-17任一项所述的隔离膜的方法，包括以下步骤：S1，提供多孔基材；S2，配制涂层浆料，将用于构成三维骨架结构的材料和填料按照预定比例在溶剂中混合，配制成涂层浆料；S3，涂布，将所述涂层浆料涂布于所述多孔基材的至少一个表面上，形成涂层并干燥，获得隔离膜，
    其中，所述隔离膜包括多孔基材和设置在所述多孔基材的至少一个表面上的涂层，所述涂层包括三维骨架结构和填料，所述填料中的至少一部分填充在所述三维骨架结构中，并且所述涂层的Zeta电位为小于0mV，
    所述涂层的Zeta电位通过如下方法测试得到：取30g涂层材料粉末与2000g去离子水搅拌混合后得到分散液，通过Zeta电位仪测试所获得的分散液的Zeta电位，即为所述涂层的Zeta电位。
  19. 根据权利要求18所述的方法，其中，
    所述涂层浆料的pH为5至10，可选为6至9；和/或，
    所述涂层浆料的静态粘度在1000mpa.s以下。
  20. 根据权利要求18或19所述的方法，其中，所述涂层浆料通过以下方式获得：步骤1，配制纳米纤维素溶液，将具有阴离子改性基团的纳米纤维素与水混合配制成所述纳米纤维素溶液，其中，所述纳米纤维素溶液的pH在5至9之间、Zeta电位为小于0mV；步骤2，配制填料溶液，所述填料溶液的pH为≥7.5、Zeta电位为小于0mV；步骤3，混合，将所述纳米纤维素溶液和所述填料溶液按照预定比例混合，即得到涂层浆料，其中，所述涂层浆料的Zeta电位在-5mV以下。
  21. 根据权利要求20所述的方法，其中，
    所述纳米纤维素溶液的浓度为1wt％至10wt％，可选为2wt％至10wt％；和/或，
    所述填料溶液的浓度为30wt％至60wt％，可选为35wt％至55wt％。
  22. 根据权利要求20或21所述的方法，其中，所述具有阴离子改性基团的纳米纤维素通过以下方式获得：将纳米纤维素粉末与改性溶液混合并反应后，经过洗涤除杂，获得具有阴离子改性基团的纤维素纳米晶须，将所获得的具有阴离子改性基团的纤维素纳米晶须的pH调节至中性，并经研磨、切割获得具有阴离子改性基团的纳米纤维素，可选地，所述改性溶液为硫酸水溶液、硼酸水溶液、磷酸水溶液、醋酸水溶液或尿素有机溶剂溶液。
  23. 根据权利要求20或21所述的方法，其中，所述填料溶液通过以下方式获得：将填料、水与改性剂混合，获得pH为≥7.5、Zeta电位为小于0mV的填料溶液，所述改性剂包括选自碱、阴离子表面活性剂和非离子表面活性剂中的至少一种；
    可选地，所述碱包括选自KOH、NaOH、NaHCO 3、LiOH、NH 4OH、Mg(OH) 2和Na 2CO 3中的至少一种；
    可选地，所述阴离子表面活性剂包括选自磺酸盐型阴离子表面活性剂、羧酸盐型阴离子表面活性剂、硫酸酯盐型阴离子表面活性剂和磷酸酯盐型阴离子表面活性剂中的至少一种，进一步可选为包括选自烷基苯磺酸盐、C12-C20烷基磺酸盐、聚丙烯酸钠、聚丙烯酸铵、羟乙基硫酸钠和C12-C20烷基硫酸钠中的至少一种；
    可选地，所述非离子表面活性剂包括选自氟代烷基乙氧基醇醚和脂肪醇聚氧乙烯醚中的至少一种。
  24. 根据权利要求18-23任一项所述的方法，还包括以下步骤：S4，二次涂布，将包含颗粒状的粘结剂的浆料涂布于所述涂层的至少一部分表面上，干燥后形成粘接层。
  25. 一种二次电池，其包括权利要求1-17任一项所述的隔离膜或通过权利要求18-24任一项所述的方法制备的隔离膜。
  26. 一种用电装置，其包括权利要求25所述的二次电池。
PCT/CN2022/112582 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置 Ceased WO2023245837A1 (zh)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP22947578.5A EP4542754A4 (en) 2022-06-24 2022-08-15 SEPARATOR, ITS PREPARATION METHOD, AND SECONDARY BATTERY AND RELATED ELECTRICAL APPLIANCE
KR1020247039011A KR20250007598A (ko) 2022-06-24 2022-08-15 세퍼레이터, 이의 제조 방법, 이와 관련된 이차 전지 및 전기 장치
CN202280018804.7A CN116918160A (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置
JP2024569000A JP7850288B2 (ja) 2022-06-24 2022-08-15 セパレータ、その製造方法及びそれに関連する二次電池並びに電気消費装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/CN2022/101261 WO2023245655A1 (zh) 2022-06-24 2022-06-24 一种隔离膜、其制备方法及其相关的二次电池和用电装置
CNPCT/CN2022/101261 2022-06-24

Publications (1)

Publication Number Publication Date
WO2023245837A1 true WO2023245837A1 (zh) 2023-12-28

Family

ID=88311177

Family Applications (6)

Application Number Title Priority Date Filing Date
PCT/CN2022/101261 Ceased WO2023245655A1 (zh) 2022-06-24 2022-06-24 一种隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112589 Ceased WO2023245840A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112587 Ceased WO2023245839A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112582 Ceased WO2023245837A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112583 Ceased WO2023245838A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112580 Ceased WO2023245836A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置

Family Applications Before (3)

Application Number Title Priority Date Filing Date
PCT/CN2022/101261 Ceased WO2023245655A1 (zh) 2022-06-24 2022-06-24 一种隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112589 Ceased WO2023245840A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112587 Ceased WO2023245839A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置

Family Applications After (2)

Application Number Title Priority Date Filing Date
PCT/CN2022/112583 Ceased WO2023245838A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置
PCT/CN2022/112580 Ceased WO2023245836A1 (zh) 2022-06-24 2022-08-15 隔离膜、其制备方法及其相关的二次电池和用电装置

Country Status (6)

Country Link
US (1) US20240120614A1 (zh)
EP (1) EP4325648A4 (zh)
JP (1) JP7778162B2 (zh)
KR (1) KR102929111B1 (zh)
CN (1) CN116897461B (zh)
WO (6) WO2023245655A1 (zh)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117199343B (zh) * 2023-11-08 2024-08-09 宁德时代新能源科技股份有限公司 电池单体和含有其的用电装置
CN118281482A (zh) * 2024-04-11 2024-07-02 北京理工大学 一种pvdf基多孔分层复合膜、制备方法及应用
KR102738862B1 (ko) 2024-07-01 2024-12-06 주식회사 에이엠티스 이차 전지용 분리막
CN121769430A (zh) * 2024-09-30 2026-03-31 宁德时代新能源科技股份有限公司 隔离膜及其制备方法、二次电池单体、电池装置和用电装置
WO2026084367A1 (ko) * 2024-10-16 2026-04-23 주식회사 엘지에너지솔루션 전기화학소자용 분리막 및 이를 포함하는 전기화학소자
CN119875170B (zh) * 2025-01-20 2025-11-18 湖南大学 一种氟化镁纳米纤维薄膜及其制备方法和应用
CN119994397A (zh) * 2025-02-11 2025-05-13 泰州集萃丰芳新材料科技有限公司 一种无负极结构锂电池用芳纶隔膜
CN120165177B (zh) * 2025-04-01 2025-12-26 河南科高辐射化工科技有限公司 一种纤维素基电池隔膜及其制备方法和应用

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104852006A (zh) * 2015-04-13 2015-08-19 江苏华东锂电技术研究院有限公司 复合隔膜及其制备方法,以及锂离子电池
CN110323391A (zh) * 2018-03-30 2019-10-11 比亚迪股份有限公司 聚合物隔膜及其制备方法和分散体以及锂离子电池及其制备方法
CN110492045A (zh) * 2019-08-27 2019-11-22 安徽新衡新材料科技有限公司 一种锂硫电池隔膜及其制备方法和应用
CN110959205A (zh) * 2017-06-02 2020-04-03 协和化学工业株式会社 用于非水性二次电池用隔膜的氢氧化镁、非水性二次电池用隔膜及非水性二次电池
CN113285070A (zh) * 2021-04-30 2021-08-20 天津大学 一种孔隙可调的MXene致密多孔膜的制备方法及其应用

Family Cites Families (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB120083A (en) 1917-10-24 1918-10-24 Ethelbert Harris Improvements in or relating to Means or Apparatus for Cooling Electric Motors.
JPH117936A (ja) * 1997-06-16 1999-01-12 Mitsubishi Paper Mills Ltd 電池用セパレータおよび電池
JP4724223B2 (ja) * 2006-09-07 2011-07-13 日立マクセル株式会社 電池用セパレータの製造方法
CA2824635A1 (en) * 2011-10-13 2013-04-18 Tokushu Tokai Paper Co., Ltd. Separator for electrochemical device and process for preparing the same
CN103947009B (zh) 2011-11-15 2016-03-09 帝人株式会社 非水系二次电池用隔膜及其制造方法以及非水系二次电池
WO2013077162A1 (ja) * 2011-11-25 2013-05-30 日産自動車株式会社 電気デバイス用セパレータおよびこれを用いた電気デバイス
WO2013146811A1 (ja) * 2012-03-27 2013-10-03 東レ株式会社 積層多孔質フィルムおよび蓄電デバイス用セパレータ
CN104979516B (zh) * 2014-04-10 2018-08-03 宁德时代新能源科技股份有限公司 电化学装置及电化学装置隔离膜的制备方法
KR20170127422A (ko) * 2015-03-09 2017-11-21 다이헤이요 세멘토 가부시키가이샤 이차전지용 양극 활물질 및 그 제조방법
US20170214020A1 (en) * 2016-01-22 2017-07-27 Samsung Electronics Co., Ltd. Separator for nonaqueous electrolyte secondary battery
CN107799702B (zh) * 2016-08-29 2021-03-26 比亚迪股份有限公司 一种陶瓷隔膜和锂离子电池及其制备方法
CN107871620A (zh) * 2016-09-27 2018-04-03 宁德新能源科技有限公司 隔离膜及储能装置
JP6390815B2 (ja) * 2016-10-14 2018-09-19 王子ホールディングス株式会社 電池用セパレータ塗液用増粘剤、電池用セパレータ塗液及び電池用セパレータ
JP7060917B2 (ja) 2016-10-14 2022-04-27 王子ホールディングス株式会社 電池用セパレータ塗液及び電池用セパレータ
JP6988086B2 (ja) * 2016-12-22 2022-01-05 王子ホールディングス株式会社 電池用セパレータ塗液及び電池用セパレータ
CN108933216B (zh) * 2017-05-27 2020-10-30 北京师范大学 一种包含石墨烯/纤维素复合材料的隔膜及其制备方法
CN107275550B (zh) * 2017-06-20 2020-07-07 深圳市星源材质科技股份有限公司 一种陶瓷和聚合物复合涂覆锂离子隔膜及其制备方法
CN109428035B (zh) * 2017-08-31 2020-11-06 比亚迪股份有限公司 电池隔膜及其制备方法和锂离子电池
CN107611320B (zh) * 2017-09-08 2021-06-29 上海凯矜新材料科技有限公司 锂电池涂布隔膜用水性浆料、锂电池涂布隔膜以及它们的制备方法
CN109841779A (zh) * 2017-11-24 2019-06-04 深圳市比亚迪锂电池有限公司 一种电池隔膜及其制备方法和电池
KR102209826B1 (ko) * 2018-03-06 2021-01-29 삼성에스디아이 주식회사 분리막, 이의 제조방법 및 이를 포함하는 리튬전지
CN110364662B (zh) * 2018-04-11 2022-07-05 宁德新能源科技有限公司 隔离膜和电化学装置
CN109671894B (zh) * 2018-11-29 2021-06-15 明基材料（芜湖）有限公司 低含水率隔离膜及其制造方法
CN111326697B (zh) 2018-12-14 2023-07-11 田口智浩 一种涂覆的隔膜及其制备方法
CN117996356A (zh) * 2019-03-18 2024-05-07 宁德新能源科技有限公司 隔离膜和电化学装置
CN111341974B (zh) 2020-03-13 2022-03-11 江苏厚生新能源科技有限公司 Pvdf涂胶隔膜及其制备方法、pvdf涂胶层、锂电池
US20230120595A1 (en) * 2020-04-17 2023-04-20 Shenzhen Senior Technology Material Co., Ltd. Composition, composite separator and preparation method therefor, and lithium ion battery
KR102352401B1 (ko) 2020-05-15 2022-01-19 엘지전자 주식회사 분리막 구조, 그 제조 방법 및 이를 이용한 이차전지
CN113013549B (zh) * 2021-01-28 2021-11-02 清华大学 一种轻量化锂离子电池隔膜用涂层材料及其制备方法和轻量化锂离子电池复合隔膜
CN113013551B (zh) * 2021-01-28 2021-11-23 清华大学 一种锂电池隔膜用水性纳米复合改性材料及其制备方法和轻量化锂电池隔膜
WO2022205156A1 (zh) * 2021-03-31 2022-10-06 宁德新能源科技有限公司 一种隔离膜及包含该隔离膜的电化学装置和电子装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104852006A (zh) * 2015-04-13 2015-08-19 江苏华东锂电技术研究院有限公司 复合隔膜及其制备方法,以及锂离子电池
CN110959205A (zh) * 2017-06-02 2020-04-03 协和化学工业株式会社 用于非水性二次电池用隔膜的氢氧化镁、非水性二次电池用隔膜及非水性二次电池
CN110323391A (zh) * 2018-03-30 2019-10-11 比亚迪股份有限公司 聚合物隔膜及其制备方法和分散体以及锂离子电池及其制备方法
CN110492045A (zh) * 2019-08-27 2019-11-22 安徽新衡新材料科技有限公司 一种锂硫电池隔膜及其制备方法和应用
CN113285070A (zh) * 2021-04-30 2021-08-20 天津大学 一种孔隙可调的MXene致密多孔膜的制备方法及其应用

Also Published As

Publication number Publication date
KR20240001699A (ko) 2024-01-03
WO2023245840A1 (zh) 2023-12-28
EP4325648A4 (en) 2025-03-26
JP7778162B2 (ja) 2025-12-01
WO2023245655A1 (zh) 2023-12-28
US20240120614A1 (en) 2024-04-11
KR102929111B1 (ko) 2026-02-23
WO2023245839A1 (zh) 2023-12-28
WO2023245836A1 (zh) 2023-12-28
EP4325648A1 (en) 2024-02-21
CN116897461B (zh) 2024-09-06
JP2024527671A (ja) 2024-07-26
WO2023245838A1 (zh) 2023-12-28
CN116897461A (zh) 2023-10-17

Similar Documents

Publication Publication Date Title
US20250125489A1 (en) Separator, method for preparing the same and secondary battery and electrical device related thereto
WO2023245837A1 (zh) 隔离膜、其制备方法及其相关的二次电池和用电装置
EP4542754A1 (en) Separator, preparation method therefor, and secondary battery and electric apparatus related thereto
CN116897462B (zh) 隔离膜、其制备方法及其相关的二次电池和用电装置
CN117199343A (zh) 电池单体和含有其的用电装置
JP2025528455A (ja) セパレータ、その製造方法及びそれに関連する二次電池ならびに電力消費装置
US20250125488A1 (en) Separator, method for preparing the same and secondary battery and electrical device related thereto
CN117044026B (zh) 隔离膜、其制备方法及其相关的二次电池和用电装置
US20250122398A1 (en) Separator, method for preparing the same and secondary battery and electrical device related thereto
US20250125491A1 (en) Separator, method for preparing the same and secondary battery and electrical device related thereto
WO2024036820A1 (zh) 隔离膜、其制备方法及其相关的二次电池和用电装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22947578

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2024569000

Country of ref document: JP

ENP Entry into the national phase

Ref document number: 20247039011

Country of ref document: KR

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 1020247039011

Country of ref document: KR

WWE Wipo information: entry into national phase

Ref document number: 2022947578

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2022947578

Country of ref document: EP

Effective date: 20250114

WWP Wipo information: published in national office

Ref document number: 2022947578

Country of ref document: EP