WO2023123013A1 - 绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及用电装置 - Google Patents

绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及用电装置 Download PDF

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WO2023123013A1
WO2023123013A1 PCT/CN2021/142341 CN2021142341W WO2023123013A1 WO 2023123013 A1 WO2023123013 A1 WO 2023123013A1 CN 2021142341 W CN2021142341 W CN 2021142341W WO 2023123013 A1 WO2023123013 A1 WO 2023123013A1
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Prior art keywords
insulating
positive electrode
resin
slurry
optionally
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PCT/CN2021/142341
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English (en)
French (fr)
Inventor
艾少华
郑义
孙成栋
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宁德时代新能源科技股份有限公司
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Priority to CN202180093443.8A priority Critical patent/CN116848725A/zh
Priority to EP21939989.6A priority patent/EP4231437A1/en
Priority to KR1020237000689A priority patent/KR20230106145A/ko
Priority to PCT/CN2021/142341 priority patent/WO2023123013A1/zh
Priority to JP2023501548A priority patent/JP2024508065A/ja
Priority to US18/109,277 priority patent/US20230207815A1/en
Publication of WO2023123013A1 publication Critical patent/WO2023123013A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated 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
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • 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
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the application belongs to the field of battery technology, and in particular relates to an insulating slurry and a preparation method thereof, a positive pole piece, a secondary battery, a battery module, a battery pack and an electrical device.
  • the purpose of the present application is to provide an insulating slurry and its preparation method, positive pole piece, secondary battery, battery module, battery pack and electrical device, aiming to increase the coating speed of the insulating slurry and the efficiency of the secondary battery at the same time. safety performance.
  • the first aspect of the present application provides an insulating paste, including a resin, an inorganic filler and an organic solvent, wherein the resin is selected from polyfluorinated olefin resins prepared by suspension polymerization, and the inorganic filler is selected from two-dimensional inorganic materials.
  • the migration of the insulating slurry to the positive electrode slurry coating area can be restricted by using the polyfluorinated olefin resin prepared by the suspension polymerization method in combination with the two-dimensional inorganic material, And it can also significantly reduce the fuzzy width of the fusion zone while increasing the coating speed, and improve the safety performance of the secondary battery.
  • the technical solution of the insulating paste of the present application can also ensure that the secondary battery has high energy density.
  • the insulating coating prepared by the insulating slurry of the present application can simultaneously have high mechanical strength, high heat resistance, high insulation, high adhesion and excellent electrolyte resistance, even if the negative electrode active material layer is damaged due to foreign matter, burrs, etc.
  • the separation film is pierced for other reasons and touches the positive electrode sheet, the negative electrode active material layer and the positive electrode current collector will not be directly contacted, thereby ensuring the high safety performance of the secondary battery.
  • the mass percentage w1 of the resin is 1% to 5%
  • the mass percentage w2 of the inorganic filler is 5% to 5%. 35%
  • the mass percentage w3 of the organic solvent is 60%-94%.
  • w1/w2 is 0.05-1.
  • w1/w2 is 0.1-1.
  • w1/w2 is in an appropriate range, it can effectively reduce the fuzzy width of the fusion zone while ensuring that the insulating coating has high mechanical strength, high heat resistance, high insulation, high adhesion and excellent electrolytic resistance. liquid.
  • the viscosity of the insulating paste at 25° C. is 1000 cps ⁇ 20000 cps.
  • the viscosity of the insulating slurry at 25° C. is 3000 cps ⁇ 8000 cps.
  • the number average molecular weight of the polyfluorinated olefin resin is 600,000-1,500,000.
  • the polyfluorinated olefin resin has a number average molecular weight of 1,100,000-1,300,000.
  • the polyfluorinated olefin resin has a crystallinity of 30% to 60%.
  • the polyfluorinated olefin resin has a crystallinity of 40%-50%.
  • the polyfluorinated olefin resin has a melting point of 150°C to 180°C.
  • the polyfluorinated olefin resin has a melting point of 155°C to 175°C.
  • the polyfluorinated olefin resin is selected from polyvinylidene fluoride resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, vinylidene fluoride-hexafluoropropylene copolymer resin, vinylidene fluoride- At least one of trifluoroethylene copolymer resin, vinylidene fluoride-chlorotrifluoroethylene copolymer resin, vinylidene fluoride-tetrafluoroethylene copolymer resin, and vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin.
  • the shape of the two-dimensional inorganic material is layered, flake or thin plate.
  • the two-dimensional inorganic material is selected from at least one of layered silicates and two-dimensional molecular sieves.
  • the morphology of layered silicate and two-dimensional molecular sieve is layered, flake or thin plate, and when the insulating slurry migrates to the positive electrode slurry coating area, it can reduce the migration speed, thereby reducing the The blur width of the blend zone.
  • the layered silicate and the two-dimensional molecular sieve also have strong adsorption capacity, and can combine with the resin in the insulating slurry through van der Waals force, thereby further reducing the migration speed of the insulating slurry and the fuzzy width of the fusion zone.
  • the layered silicate includes at least one of mica powder, fluorphlogopite powder, talcum powder, hydrotalcite, and hydrotalcite-like.
  • the two-dimensional molecular sieve includes at least one of MWW type, SAPO type, FER type, and PLS-n type molecular sieves.
  • the volume average particle diameter Dv50 of the two-dimensional inorganic material is 0.5 ⁇ m ⁇ 10 ⁇ m.
  • the volume average particle diameter Dv50 of the two-dimensional inorganic material is 0.5 ⁇ m ⁇ 5 ⁇ m.
  • the aspect ratio of the two-dimensional inorganic material is ⁇ 50:1.
  • the aspect ratio of the two-dimensional inorganic material is 50:1 ⁇ 100:1.
  • the organic solvent includes N-methylpyrrolidone, triethyl phosphate, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide at least one of the
  • the mass percentage of the emulsifier in the insulating slurry is less than or equal to 1/1000000.
  • the mass percentage of the emulsifier in the insulating slurry is 0%.
  • the second aspect of the present application provides a method for preparing an insulating slurry, which includes the following steps: S100, uniformly dispersing the organic solvent and the inorganic filler to obtain the first slurry; S200, injecting the obtained first slurry in the dispersed state Add resin particles to the mixture, and evenly disperse to obtain insulating slurry; wherein, the inorganic filler is selected from at least one of two-dimensional inorganic materials, and the resin particles are selected from at least one of polyfluorinated olefin resins prepared by suspension polymerization. A sort of.
  • the mass percentage of the resin particles is 1% to 5%, and the mass percentage of the inorganic filler is 5% to 35%. %, the mass percentage of the organic solvent is 60% to 94%.
  • the dispersion linear velocity is 20 m/s-100 m/s, and the dispersion time is 15 min-120 min.
  • the dispersion linear velocity is 20m/s-100m/s, and the dispersion time is 120min-480min.
  • the method further includes: S300, filtering the obtained insulating slurry.
  • the obtained insulating slurry is filtered through a 100-200 mesh filter.
  • the resin particles are primary particles.
  • the volume average particle diameter Dv50 of the primary particles is 20 ⁇ m ⁇ 150 ⁇ m.
  • the volume average particle diameter Dv50 of the primary particles is 50 ⁇ m ⁇ 100 ⁇ m.
  • the third aspect of the present application provides a positive electrode sheet, including a positive electrode current collector, a positive electrode active material layer, and an insulating coating, wherein the positive electrode active material layer is located on at least part of the surface of the positive electrode current collector, and the insulating coating is located on The surface of the positive electrode current collector is in contact with the edge of the positive electrode active material layer along the length direction of the positive electrode current collector, wherein the insulating coating is a layer formed by drying the insulating slurry described in the first aspect of the present application , or a layer formed after drying the insulating paste prepared by the method described in the second aspect of the present application.
  • the thickness of the insulating coating is 2 ⁇ m ⁇ 150 ⁇ m.
  • the width of the insulating coating is 0.1mm ⁇ 15mm.
  • a fourth aspect of the present application provides a secondary battery, which includes the positive electrode sheet of the third aspect of the present application.
  • a fifth aspect of the present application provides a battery module, which includes the secondary battery of the fourth aspect of the present application.
  • a sixth aspect of the present application provides a battery pack, which includes one of the secondary battery of the fourth aspect of the present application and the battery module of the fifth aspect.
  • a seventh aspect of the present application provides an electric device, which includes at least one of the secondary battery of the fourth aspect of the present application, the battery module of the fifth aspect, and the battery pack of the sixth aspect.
  • the insulating slurry of the present application uses the polyfluorinated olefin resin prepared by the suspension polymerization method in combination with the two-dimensional inorganic material, which can limit the migration of the insulating slurry to the positive electrode slurry coating area, and can also be used in the lifting coating At the same time, the fuzzy width of the fusion zone is significantly reduced, and the safety performance of the secondary battery is improved.
  • the insulating paste of the present application can also ensure high energy density of the secondary battery.
  • the insulating coating prepared by the insulating slurry of the present application can simultaneously have high mechanical strength, high heat resistance, high insulation, high adhesion and excellent electrolyte resistance, even if the negative electrode active material layer is damaged due to foreign matter, burrs, etc.
  • the battery module, battery pack and electric device of the present application include the secondary battery provided by the present application, and thus have at least the same advantages as the secondary battery.
  • FIG. 1 is a schematic diagram of an embodiment of the positive electrode sheet of the present application.
  • FIG. 2 is a schematic diagram of an embodiment of the secondary battery of the present application.
  • FIG. 3 is an exploded view of an embodiment of the secondary battery of FIG. 2 .
  • Fig. 4 is a schematic diagram of an embodiment of the battery module of the present application.
  • FIG. 5 is a schematic diagram of an embodiment of the battery pack of the present application.
  • FIG. 6 is an exploded view of the embodiment of the battery pack shown in FIG. 5 .
  • FIG. 7 is a schematic diagram of an embodiment of an electrical device including the secondary battery of the present application as a power source.
  • Fig. 8 is a comparison chart of the results of high-speed coating of insulating pastes prepared in Example 1 and Comparative Example 1.
  • ranges disclosed herein are defined in terms of lower and upper limits, and 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 and may be combined arbitrarily, ie 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, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, 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" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • 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 in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, 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) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: 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).
  • two-dimensional inorganic material refers to an inorganic material with a two-dimensional or nearly two-dimensional structure, for example, an inorganic material with a layered, flake-like or thin-plate shape.
  • Secondary batteries also known as rechargeable batteries or accumulators, refer to batteries that can be activated by charging the active materials and continue to be used after the battery is discharged.
  • a secondary battery includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows active ions to pass through.
  • the electrolyte plays the role of conducting active ions between the positive pole piece and the negative pole piece.
  • the short-circuit forms in the secondary battery mainly include the following four types: (1) short-circuit between the negative electrode current collector and the positive electrode current collector; (2) short-circuit between the negative electrode active material layer and the positive electrode active material layer; (3) negative electrode active material A short circuit between the layer and the positive electrode current collector; (4) a short circuit between the positive electrode active material layer and the negative electrode current collector.
  • a common strategy is to insulate the surface of the positive electrode current collector adjacent to the positive electrode active material layer, such as coating an insulating coating.
  • the existing insulating slurry will migrate to the positive electrode slurry coating area, so that after drying, a fusion zone (commonly known as virtual space) will be formed at the boundary between the positive electrode active material layer and the insulating coating layer.
  • the fuzzy width of the fusion zone is actually the distance that the insulating slurry migrates to the positive electrode slurry coating area, or the width of the positive electrode active material layer covered by the insulating coating .
  • the appearance of the fusion zone will lead to difficulties in the positioning of the CCD (Charge Coupled Device) visual inspection equipment during the laser die-cutting process, inaccurate die-cutting dimensions of the positive pole piece, and even endanger the Overhang of the secondary battery, thus bringing serious safety to the secondary battery Hidden danger.
  • the fusion region is actually a region where the components of the insulating coating and the positive electrode active material layer are fused together, or the region where the positive electrode active material layer is covered by the insulating coating.
  • the ion conductivity of the fusion region is usually poor, thereby blocking / Hinder the extraction and insertion of some active ions, therefore, the appearance of the fusion zone will also reduce the energy density of the secondary battery, and the wider the fusion zone, the more obvious the energy density drop of the secondary battery.
  • the main reason is that the faster the coating speed, the higher the corresponding drying temperature, the better fluidity and lower surface tension of the insulating slurry at high temperature, so it is easier to migrate to the positive electrode slurry coating area.
  • the first aspect of the embodiment of the present application provides an insulating slurry, including a resin, an inorganic filler, and an organic solvent, wherein the resin is selected from polyfluorinated olefin resins prepared by suspension polymerization, and the inorganic filler is selected from two dimensional inorganic materials.
  • Polyfluorinated olefin resins are currently widely used in positive electrode pastes and insulating pastes due to their excellent adhesion, electrolyte resistance, and electrochemical oxidation resistance.
  • the insulating slurry using polyfluorinated olefin resin inevitably migrates to the positive electrode slurry coating area, and after drying, a wide fusion zone will be formed at the boundary between the positive electrode active material layer and the insulating coating; at the same time , the faster the coating speed, the wider the fusion zone, which restricts the improvement of coating speed.
  • technicians have not found the root cause of the formation of the fusion zone, so in order to reduce the blur width of the fusion zone and ensure the high safety performance of the secondary battery, the strategy usually adopted in the prior art is to reduce the coating speed.
  • Emulsion polymerization systems usually include four basic components: monomers, emulsifiers, initiators, and water.
  • the role of emulsifiers in emulsion polymerization systems includes: reducing surface tension and dispersing monomers into fine droplets; Forms a protective layer on the surface to prevent condensation; solubilization.
  • Fluorine-containing emulsifiers are generally used in the preparation of polyfluorinated olefin resins by emulsion polymerization.
  • the most commonly used fluorine-containing emulsifiers include perfluorooctanoic acid (Pentadecafluorooctanoic acid, PFOA) and its alkali metal salts, perfluorobutylsulfonic acid, perfluorobutyl Sulfonates, perfluoropolyethers, fluorine-containing polyether acids and salts thereof (for example, perfluoropolyether carboxylic acid, ammonium perfluoropolyether carboxylate), and the like.
  • PFOA perfluorooctanoic acid
  • PFOA perfluorobutylsulfonic acid
  • perfluorobutyl Sulfonates perfluoropolyethers
  • fluorine-containing polyether acids and salts thereof for example, perfluor
  • the emulsifier in the polyfluorinated olefin resin prepared by the emulsion polymerization method is difficult to remove, resulting in a low surface tension of the insulating paste; in addition, fluorine has the largest electronegativity and has a strong electron-attracting property , the C-F bond energy is higher, so when the emulsifier used is a fluorine-containing emulsifier, its surface activity is higher and the surface tension is lower, which leads to a further reduction in the surface tension of the insulating slurry, which is significantly smaller than that of the positive electrode slurry Surface Tension. Therefore, the insulating paste of polyfluorinated olefin resin prepared by emulsion polymerization inevitably forms a wider fusion zone, which restricts the improvement of coating speed.
  • the insulating slurry of this application adopts the polyfluorinated olefin resin prepared by the suspension polymerization method.
  • the suspension polymerization system usually includes five basic components: monomer, dispersant, initiator, chain transfer agent and water.
  • the main functions of the dispersant include: adsorbing on the surface of the monomer liquid to maintain the stability of the polymerization system; Aggregation occurs.
  • Water-soluble dispersants such as cellulose ether and polyvinyl alcohol, are generally used in the preparation of polyfluorinated olefin resins by suspension polymerization. Compared with emulsion polymerization, the dispersants adsorbed on polyfluorinated olefin resin particles prepared by suspension polymerization are less Less, and easy to remove, higher purity resin.
  • the insulating slurry of the present application does not contain or substantially contains no emulsifier, and its mass percentage is lower than the detection limit, for example, ⁇ 1/1000000. Therefore, the insulating slurry obtained by the polyfluorinated olefin resin prepared by the suspension polymerization method in the present application has higher surface tension than the existing insulating slurry, thereby reducing the surface tension difference with the positive electrode slurry, and then The insulating paste of the present application can also reduce the blur width of the fusion zone.
  • a two-dimensional inorganic material is used as the inorganic filler.
  • the inorganic filler has a two-dimensional (or nearly two-dimensional) structure, the diffusion path of the liquid solution (ie, the resin solution) to the positive electrode slurry coating region becomes longer and the diffusion resistance becomes larger. Therefore, using a two-dimensional inorganic material as the inorganic filler can reduce the migration speed of the insulating slurry, limit the migration of the insulating slurry to the positive electrode slurry coating area, and further reduce the fuzzy width of the fusion zone.
  • the insulating slurry of the present application by using the polyfluorinated olefin resin prepared by the suspension polymerization method in combination with the two-dimensional inorganic material, it is possible to limit the application area of the insulating slurry to the positive electrode slurry Migration, and can also significantly reduce the fuzzy width of the fusion zone while increasing the coating speed, and improve the safety performance of the secondary battery.
  • the blur width of the fusion zone when the coating speed is above 60m/min, the blur width of the fusion zone can be ⁇ 0.5mm, or even ⁇ 0.2mm, which is significantly better than the industry average (when the coating speed is 30m/min ⁇ 40m/min , the blur width of the fusion zone > 2mm).
  • the technical solution of the insulating paste of the present application can also ensure that the secondary battery has high energy density.
  • the insulating coating prepared by the insulating slurry of the present application can simultaneously have high mechanical strength, high heat resistance, high insulation, high adhesion and excellent electrolyte resistance, even if the negative electrode active material layer is damaged due to foreign matter, burrs, etc.
  • the separation film is pierced for other reasons and touches the positive electrode sheet, the negative electrode active material layer and the positive electrode current collector will not be directly contacted, thereby ensuring the high safety performance of the secondary battery.
  • the mass percentage w1 of the resin may be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% %, ranges consisting of 5% or any value above.
  • the mass percentage w1 of the resin is 1%-5%, 1.5%-5%, 2%-5%, 2.5%-5%, 3%-5%, 3.5%-5%, 4% ⁇ 5%, 1% ⁇ 4%, 1.5% ⁇ 4%, 2% ⁇ 4%, 2.5% ⁇ 4%, 3% ⁇ 4%, 3.5% ⁇ 4%, 1% ⁇ 3%, 1.5% ⁇ 3%, 2% ⁇ 3%, 2.5% ⁇ 3%, 1% ⁇ 2%, or 1.5% ⁇ 2%.
  • the resin When the mass percentage of the resin is high, the mechanical strength, heat resistance and insulation of the insulating coating are poor, and the direct contact between the negative electrode active material layer and the positive electrode current collector cannot be effectively prevented, and the risk of short circuit in the secondary battery increases.
  • the resin When the mass percentage of the resin is high, the viscosity of the insulating slurry is usually high and it is difficult to coat; when the mass percentage of the resin is low, the adhesion and electrolyte resistance of the insulating coating become poor, and it is easy to degrade from the positive electrode. The current collector falls off, and the safety performance of the secondary battery during long-term use cannot be guaranteed.
  • the insulating coating has high mechanical strength, high heat resistance, high insulation, high adhesion and excellent electrolyte resistance, even in negative active materials.
  • the layer pierces the separator due to foreign matter, burrs, etc., and contacts the positive electrode sheet, the negative active material layer will not directly contact the positive electrode current collector, thereby ensuring higher safety performance for the long-term use of the secondary battery.
  • the mass percentage w2 of the inorganic filler can be 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 35% or the range formed by any value above.
  • the mass percentage w2 of the inorganic filler is 5% to 35%, 10% to 35%, 15% to 35%, 20% to 35%, 25% to 35%, 30% to 35% , 5% ⁇ 32%, 10% ⁇ 32%, 15% ⁇ 32%, 20% ⁇ 32%, 25% ⁇ 32%, 5% ⁇ 30%, 10% ⁇ 30%, 15% ⁇ 30%, 20% % ⁇ 30%, 25% ⁇ 30%, 5% ⁇ 28%, 10% ⁇ 28%, 15% ⁇ 28%, 20% ⁇ 28%, 25% ⁇ 28%, 5% ⁇ 26%, 10% ⁇ 26%, 15%-26%, 20%-26%, 5%-24%, 10%-24%, 15%-24%, 20%-24%, 5%-22%, 10%-22% , 15% to 22%, 5% to 20%, 10% to 20%, or 15% to 20%.
  • the mass percentage of the inorganic filler When the mass percentage of the inorganic filler is high, the adhesion and electrolyte resistance of the insulating coating will be deteriorated, and it will easily fall off from the positive electrode current collector, which cannot guarantee the safety performance of the secondary battery during long-term use; the quality of the inorganic filler When the percentage is low, the mechanical strength, heat resistance and insulation of the insulating coating are poor, and the direct contact between the negative electrode active material layer and the positive electrode current collector cannot be effectively prevented, and the risk of short circuit in the secondary battery increases.
  • the insulating coating has high mechanical strength, high heat resistance, high insulation, high cohesiveness and excellent electrolyte resistance, even when the negative electrode is active
  • the negative active material layer will not directly contact the positive electrode current collector, thereby ensuring higher safety performance of the secondary battery for long-term use.
  • the mass percentage w3 of the organic solvent may be 60%, 65%, 70%, 75%, 80%, 85%, 90%, 94% or above any value of the range.
  • the mass percentage w3 of the organic solvent is 60%-94%, 65%-94%, 70%-94%, 75%-94%, 80%-94%, 85%-94% , 90% ⁇ 94%, 60% ⁇ 90%, 65% ⁇ 90%, 70% ⁇ 90%, 75% ⁇ 90%, 80% ⁇ 90%, 85% ⁇ 90%, 60% ⁇ 85%, 65% % ⁇ 85%, 70% ⁇ 85%, 75% ⁇ 85%, 80% ⁇ 85%, 60% ⁇ 80%, 65% ⁇ 80%, 70% ⁇ 80%, 75% ⁇ 80%, 60% ⁇ 75%, 65%-75%, 70%-75%, 60%-70%, or 65%-70%.
  • the mass percentage w1 of the resin is 1%-5%
  • the mass percentage w2 of the inorganic filler is 5%-35%
  • the mass percent content w3 of the organic solvent is 60%-94%.
  • w1/w2 When w1/w2 is small, the mass percentage of inorganic filler is high, and the adhesion and electrolyte resistance of the insulating coating are poor; when w1/w2 is large, the mass percentage of inorganic filler is small and cannot be effectively
  • the resin solution is prevented from migrating to the positive electrode slurry coating area, so that the fusion area is easy to widen.
  • w1/w2 When w1/w2 is in an appropriate range, it can effectively reduce the fuzzy width of the fusion zone while ensuring that the insulating coating has high mechanical strength, high heat resistance, high insulation, high adhesion and excellent electrolytic resistance. liquid.
  • w1/w2 is 0.05-1.
  • w1/w2 is 0.1-1, 0.12-1, 0.15-1, or 0.18-1.
  • the viscosity of the insulating slurry mainly affects the coating performance of the insulating slurry.
  • the viscosity is too high, the insulating slurry cannot be coated on the surface of the positive electrode current collector; at the same time, the viscosity of the insulating slurry should not be too small.
  • the fluidity is strong, and the fusion zone is easy to widen.
  • the viscosity of the insulating paste at 25° C. is 1000 cps ⁇ 20000 cps.
  • the viscosity of the insulating paste at 25°C is 1000cps, 2000cps, 3000cps, 4000cps, 5000cps, 6000cps, 7000cps, 8000cps, 9000cps, 10000cps, 11000cps, 12000cps, 13000cps, 14000cps, 15000 cps, 16000cps, 17000cps, 18000cps, 19000cps, 20000cps or the range formed by any value above.
  • the viscosity of the insulating slurry at 25°C is 2000cps-20000cps, 4000cps-20000cps, 6000cps-20000cps, 8000cps-20000cps, 10000cps-20000cps, 12000cps-20000cps, 14000cps-20000cps s, 16000cps ⁇ 20000cps, 18000cps ⁇ 20000cps, 1000cps ⁇ 15000cps, 2000cps ⁇ 15000cps, 4000cps ⁇ 15000cps, 6000cps ⁇ 15000cps, 8000cps ⁇ 15000cps, 10000cps ⁇ 15000cps, 12000cps ⁇ 15000cps, 1000cps ⁇ 10000cps, 2000cps ⁇ 10000cps, 4000cps ⁇ 10000cps, 6000cps ⁇ 10000cps, 8000cps
  • the polyfluorinated olefin resin may have a moderate molecular weight considering that the insulating coating needs to have both excellent adhesion and excellent electrolyte resistance.
  • the polyfluorinated olefin resin has a number average molecular weight of 600,000-1,500,000.
  • the polyfluorinated olefin resin has a number average molecular weight of 1,100,000-1,300,000.
  • the polyfluorinated olefin resin may have a moderate degree of crystallinity.
  • the crystallinity of the polyfluorinated olefin resin is low, its swelling degree in the electrolyte is high, the electrolyte resistance of the insulating coating becomes poor, and the secondary battery is easy to fall off from the positive electrode current collector when it is used for a long time;
  • the crystallinity of the polyfluorinated olefin resin is high, the processability of the positive electrode sheet thus prepared becomes poor, and the tape is easily broken during winding.
  • the polyfluorinated olefin resin has a crystallinity of 30%-60%.
  • the polyfluorinated olefin resin has a crystallinity of 40%-50%.
  • the polyfluorinated olefin resin may have a moderate melting point.
  • the melting point of the polyfluorinated olefin resin is low, its swelling degree in the electrolyte is high, the electrolyte resistance of the insulating coating becomes poor, and the secondary battery is easy to fall off from the positive current collector when the secondary battery is used for a long time;
  • the polyfluorinated olefin resin has a high melting point, the processability of the positive electrode sheet thus prepared becomes poor, and the tape is easily broken during winding.
  • the polyfluorinated olefin resin has a melting point T m of 150°C to 180°C.
  • the polyfluorinated olefin resin has a melting point of 155°C to 175°C.
  • the polyfluorinated olefin resin prepared by the suspension polymerization method is selected from polyvinylidene fluoride (PVDF) resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, vinylidene fluoride-hexafluoropropylene copolymer ( VDF-HFP) resin, vinylidene fluoride-trifluoroethylene copolymer resin, vinylidene fluoride-trifluoroethylene copolymer resin, vinylidene fluoride-tetrafluoroethylene copolymer resin, vinylidene fluoride-tetrafluoroethylene-hexafluoro At least one of propylene copolymer resins.
  • PVDF polyvinylidene fluoride
  • VDF-HFP vinylidene fluoride-hexafluoropropylene copolymer
  • VDF-HFP vinylidene fluoride-trifluoroethylene copolymer resin
  • the polyfluorinated olefin resin prepared by the suspension polymerization method can be purchased from Solvay Company or Kureha Company, etc. Of course, the polyfluorinated olefin resin prepared by the suspension polymerization method can also be obtained by synthesis. As an example, the polyfluorinated olefin resin prepared by the suspension polymerization method includes commercially available at least one of the
  • the shape of the two-dimensional inorganic material is layered, flake or thin plate.
  • the material of the two-dimensional inorganic material is selected from at least one of layered silicates and two-dimensional molecular sieves.
  • the morphology of the layered silicate and the two-dimensional molecular sieve is a two-dimensional or nearly two-dimensional structure, such as a layer, a sheet or a thin plate.
  • the crystal structure of phyllosilicate is composed of structural unit layers (or crystal layers) stacked parallel to each other.
  • the structural unit layer includes two parts, the sheet and the interlayer.
  • the sheet is usually composed of a silicon-oxygen tetrahedral sheet (Tetrahedral sheet) and metal cations (such as Mg 2+ , Fe 2+ , Al 3+ , etc.)-oxygen Octohedral sheets are formed in a 1:1 or 2:1 manner.
  • Two-dimensional molecular sieve is a kind of crystalline aluminosilicate, its spatial network structure is composed of silicon-oxygen tetrahedrons and aluminum-oxygen tetrahedrons interlaced.
  • the phyllosilicates and two-dimensional molecular sieves used in this application have a layered, flake-like or thin-plate shape.
  • the above-mentioned inorganic fillers can increase
  • the diffusion path and diffusion resistance of the liquid solution (that is, the resin solution) to the positive electrode slurry coating area can reduce the migration speed of the insulating slurry, thereby reducing the fuzzy width of the fusion zone.
  • the layered silicate and the two-dimensional molecular sieve also have strong adsorption capacity, and can combine with the resin in the insulating slurry through van der Waals force, thereby further reducing the migration speed of the insulating slurry and the fuzzy width of the fusion zone.
  • Both layered silicates and two-dimensional molecular sieves have the advantages of good thermal stability and low cost. They also have a graphite-like sheet structure, and the van der Waals force of the interlayer structure is much smaller than the ionic force in the layer. When squeezed interlayer sliding can occur. Therefore, the insulating coating using the above-mentioned inorganic filler has better heat resistance and insulating properties, thereby further improving the safety performance of the secondary battery.
  • the layered silicate and the two-dimensional molecular sieve also have good toughness, so that the positive electrode sheet prepared therefrom has good processability and is not easy to break when winding.
  • the layered silicate includes at least one of mica powder, fluorophlogopite powder, talcum powder, hydrotalcite, and hydrotalcite-like.
  • the two-dimensional molecular sieve includes at least one of MWW type, SAPO type, FER type, PLS-n type molecular sieve.
  • the two-dimensional molecular sieve includes at least one of MCM-22, MCM-49, MCM-56, SAPO-34, SAPO-18, and Al-PLS-3.
  • the insulating slurry includes at least one of mica powder and talc powder
  • some transition metal impurities in the mica powder and talc powder may be removed in advance through pickling and water washing processes. These transition metal impurities may hinder the electrochemical performance of the secondary battery, such as increasing the self-discharge of the secondary battery.
  • weak acid aqueous solution such as boric acid aqueous solution, etc.
  • strong acid dilute solution such as nitric acid, sulfuric acid or hydrochloric acid aqueous solution with a mass fraction of about 1%.
  • the volume average particle diameter Dv50 of the two-dimensional inorganic material is 0.5 ⁇ m ⁇ 10 ⁇ m.
  • the volume-average particle diameter Dv50 of the two-dimensional inorganic material is 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m or any value above.
  • the volume average particle diameter Dv50 of the two-dimensional inorganic material is 0.5 ⁇ m to 9 ⁇ m, 0.5 ⁇ m to 8 ⁇ m, 0.5 ⁇ m to 7 ⁇ m, 0.5 ⁇ m to 6 ⁇ m, 0.5 ⁇ m to 5 ⁇ m, 0.5 ⁇ m to 4 ⁇ m, 0.5 ⁇ m to 4 ⁇ m, 3 ⁇ m, 1 ⁇ m to 10 ⁇ m, 1 ⁇ m to 9 ⁇ m, 1 ⁇ m to 8 ⁇ m, 1 ⁇ m to 7 ⁇ m, 1 ⁇ m to 6 ⁇ m, 1 ⁇ m to 5 ⁇ m, 1 ⁇ m to 4 ⁇ m, or 1 ⁇ m to 3 ⁇ m.
  • the two-dimensional inorganic material usually has a relatively high diameter-thickness ratio.
  • the aspect ratio of the two-dimensional inorganic material can be ⁇ 30:1, ⁇ 40:1, ⁇ 50:1, ⁇ 60:1, ⁇ 70:1, ⁇ 80:1, ⁇ 90: 1, ⁇ 100:1, ⁇ 110:1, ⁇ 120:1, ⁇ 130:1, ⁇ 140:1, ⁇ 150:1.
  • the aspect ratio of the two-dimensional inorganic material is 50:1-150:1, 50:1-140:1, 50:1-130:1, 50:1-120 :1, 50:1 ⁇ 110:1, 50:1 ⁇ 100:1, 50:1 ⁇ 90:1, or 50:1 ⁇ 80:1.
  • NMP N-methylpyrrolidone
  • triethyl phosphate dimethyl sulfoxide
  • N,N-dimethylformamide N,N-dimethylacetamide
  • the insulating paste includes a resin, an inorganic filler and an organic solvent
  • the resin is selected from polyfluorinated olefin resins prepared by suspension polymerization
  • the inorganic filler is selected from two-dimensional inorganic materials; based on the Based on the total mass of the insulating paste, the mass percentage w1 of the resin is 1% to 5%, the mass percentage w2 of the inorganic filler is 5% to 35%, and the mass percentage of the organic solvent is w3 is 60% to 94%
  • the polyfluorinated olefin resin prepared by the suspension polymerization method is selected from polyvinylidene fluoride resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, vinylidene fluoride-hexafluoropropylene copolymer resin, Vinylidene fluoride-trifluoroethylene copolymer resin, vinylidene fluoride-trifluoroethylene copolymer resin, vinylidene flu
  • the number-average molecular weight of a resin is a well-known meaning in the art, and can be measured with instruments and methods known in the art.
  • GPC gel permeation chromatography
  • Agilent Agilent 1290 Infinity II GPC system.
  • the crystallinity of a resin is a well-known meaning in the art, and can be measured with instruments and methods known in the art.
  • differential scanning calorimetry DSC
  • Mettler-Toledo Metaltler-Toledo
  • the melting point of a resin is a well-known meaning in the art, and can be measured with instruments and methods known in the art. For example, it can be measured with reference to GB/T 29611-2013 "Determination of Glass Transition Temperature of Raw Rubber by Differential Scanning Calorimetry (DSC)", and the test can be carried out by Mettler-Toledo (Mettler-Toledo) DSC-3 type Differential Scanning Calorimeter.
  • the viscosity of the insulating paste is a well-known meaning in the art, and can be measured with instruments and methods known in the art. For example, it can be measured with reference to GB/T 2794-2013 "Determination of Viscosity of Adhesives by Single Cylinder Rotational Viscometer".
  • the volume average particle diameter Dv50 of a material is a well-known meaning in the art, which means the particle diameter corresponding to when the cumulative volume distribution percentage reaches 50%, which can be measured by instruments and methods known in the art. For example, it can be conveniently measured by laser particle size analyzer with reference to GB/T 19077-2016 particle size distribution laser diffraction method, such as the Mastersizer 2000E laser particle size analyzer of Malvern Instruments Co., Ltd., UK.
  • the aspect ratio of the two-dimensional inorganic material has a well-known meaning in the art, and can be measured with instruments and methods known in the art. For example, it can be determined by referring to JC/T 2063-2011 "Measurement Method for Diameter-thickness Ratio of Mica Powder".
  • the second aspect of the embodiment of the present application provides a method for preparing an insulating slurry, including the following steps: S100, uniformly dispersing an organic solvent and an inorganic filler to obtain a first slurry; S200, injecting Resin particles are added to the first slurry, and the insulating slurry is obtained after uniform dispersion; wherein, the inorganic filler is selected from at least one of two-dimensional inorganic materials, and the resin particles are selected from polyfluorinated olefins prepared by suspension polymerization at least one of the resins.
  • the mass percentage of the resin particles is 1% to 5%, and the mass percentage of the inorganic filler is 5% to 30%.
  • the mass percent content of the organic solvent is 65%-94%.
  • the resin particles are polyfluorinated olefin resins prepared by suspension polymerization, so the resin particles generally have a large particle size and are not easy to agglomerate.
  • the resin particles are in the form of primary particles.
  • the volume average particle diameter Dv50 of the primary particles is 20 ⁇ m ⁇ 150 ⁇ m.
  • the volume average particle diameter Dv50 of the primary particles is 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 110 ⁇ m, 120 ⁇ m, 130 ⁇ m, 140 ⁇ m, 150 ⁇ m or any of the above ranges.
  • the volume average particle diameter Dv50 of the primary particles is 30 ⁇ m-150 ⁇ m, 50 ⁇ m-150 ⁇ m, 70 ⁇ m-150 ⁇ m, 90 ⁇ m-150 ⁇ m, 20 ⁇ m-120 ⁇ m, 30 ⁇ m-120 ⁇ m, 50 ⁇ m-120 ⁇ m, 70 ⁇ m-120 ⁇ m, 90 ⁇ m-120 ⁇ m , 20 ⁇ m to 100 ⁇ m, 30 ⁇ m to 100 ⁇ m, 50 ⁇ m to 100 ⁇ m, 70 ⁇ m to 100 ⁇ m, 20 ⁇ m to 80 ⁇ m, 30 ⁇ m to 80 ⁇ m, or 50 ⁇ m to 80 ⁇ m.
  • the dispersion line speed is 20m/s-100m/s, and the dispersion time is 15min-120min.
  • the dispersion line speed is 20m/s-100m/s, and the dispersion time is 120min-480min.
  • the method further includes: S300, filtering the obtained insulating slurry.
  • the obtained insulating slurry is filtered through a 100-200 mesh filter.
  • the method for preparing insulating paste of the second aspect of the embodiment of the present application can prepare the insulating paste of the first aspect of the embodiment of the present application. It should be noted that, for relevant parameters of the insulating paste prepared by the method for preparing insulating paste in the second aspect of the embodiment of the present application, refer to the insulating paste provided in the examples of the first aspect of the embodiment of the present application.
  • the third aspect of the embodiment of the present application provides a positive electrode sheet, including a positive electrode current collector, a positive electrode active material layer, and an insulating coating, wherein the positive electrode active material layer is located on at least part of the surface of the positive electrode current collector, and the The insulating coating is located on the surface of the positive electrode current collector and is in contact with the edge of the positive electrode active material layer along the length direction of the positive electrode current collector.
  • the insulating coating is according to any embodiment of the first aspect of the implementation mode of the present application.
  • the positive electrode sheet of the present application can reduce the probability of direct contact between the negative electrode active material layer and the positive electrode current collector, ensuring high safety performance of the secondary battery.
  • the positive electrode sheet of the present application also has good processability, and the tape is not easy to be broken during winding.
  • the insulating coating is located on one or both sides of the positive electrode active material layer along the length direction.
  • the insulating coating is located on both sides of the positive electrode active material layer along the length direction.
  • FIG. 1 is a schematic diagram of an embodiment of the positive electrode sheet of the present application. As shown in FIG. 1 , the positive electrode sheet includes a positive electrode current collector 101, a positive electrode active material layer 102, and an insulating coating 103. The insulating coating 103 is located on both sides of the positive electrode active material layer 102 along the length direction L, but this application does not limited to this.
  • the present application has no special limitation on the thickness of the insulating coating, which can be adjusted according to actual needs.
  • the insulating coating has a thickness of 2 ⁇ m ⁇ 150 ⁇ m.
  • the present application has no special limitation on the width of the insulating coating, which can be adjusted according to actual needs.
  • the insulating coating has a width of 0.1mm ⁇ 15mm.
  • the positive current collector has two opposing surfaces in its thickness direction, and the positive active material layer is disposed on any one or both of the two opposing surfaces of the positive current collector.
  • the positive current collector has two opposing surfaces in its thickness direction, and the insulating coating is disposed on any one or both of the two opposing surfaces of the positive current collector.
  • the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be a positive electrode active material known in the art for secondary batteries.
  • the positive active material may include at least one of lithium transition metal oxides, olivine-structured lithium-containing phosphates, and their respective modification compounds.
  • lithium transition metal oxides may include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium At least one of nickel cobalt aluminum oxide and its modified compounds.
  • Examples of the lithium-containing phosphate of the olivine structure may include lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium iron phosphate and carbon, At least one of composite materials and their respective modifying compounds.
  • the present application is not limited to these materials, and other conventionally known materials that can be used as a secondary battery positive electrode active material may also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • the modified compounds of the above-mentioned positive electrode active materials may be doping modification or surface coating modification of the positive electrode active materials.
  • the positive electrode active material includes at least one of olivine-structured lithium-containing phosphate and modified compounds thereof.
  • the positive electrode active material layer may further optionally include 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, graphene , at least one of carbon nanofibers.
  • the mass percentage of the positive electrode conductive agent is ⁇ 5%.
  • the positive electrode active material layer may further optionally include a positive electrode binder.
  • the positive electrode binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene - At least one of propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • the mass percentage of the positive electrode binder is ⁇ 5%.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base and a metal material layer formed on at least one surface of the polymer material base.
  • the metal material may be selected from at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
  • the polymer material base layer can be selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), poly Ethylene (PE), etc.
  • the positive electrode active material 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, an optional conductive agent, an optional binder and any other components in a solvent and stirring them uniformly.
  • the solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.
  • the preparation method of the positive electrode sheet of the present application is well known.
  • the positive electrode slurry and the insulating slurry described in any embodiment of the first aspect of the implementation mode of the present application can be coated on the positive electrode current collector, dried and cold pressed.
  • a fourth aspect of the embodiments of the present application provides a secondary battery, including a positive electrode sheet, a negative electrode sheet, and an electrolyte.
  • a secondary battery including a positive electrode sheet, a negative electrode sheet, and an electrolyte.
  • active ions are intercalated and extracted back and forth between the positive pole piece and the negative pole piece, and the electrolyte plays a role of conduction between the positive pole piece and the negative pole piece. The role of active ions.
  • the positive pole piece used in the secondary battery of the present application is the positive pole piece described in any one of the examples of the third aspect of the implementation mode of the present application.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector and including negative electrode active materials.
  • the anode current collector has two opposing surfaces in its own thickness direction, and the anode active material layer is disposed on any one or both of the two opposing surfaces of the anode current collector.
  • the negative electrode active material may be a negative electrode active material known in the art for secondary batteries.
  • the negative electrode active material includes but not limited to at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate.
  • the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy materials.
  • the tin-based material may include at least one of elemental tin, tin oxide, and tin alloy materials.
  • the present application is not limited to these materials, and other conventionally known materials that can be used as negative electrode active materials for secondary batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode active material layer may further optionally include 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 olefin and carbon nanofibers.
  • the mass percentage of the negative electrode conductive agent is ⁇ 5%.
  • the negative electrode active material layer may further optionally include 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, sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), carboxymethyl chitosan (CMCS) kind.
  • SBR styrene-butadiene rubber
  • SR-1B water-soluble unsaturated resin
  • acrylic resin for example, At least one of polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), carboxymethyl chitosan (CMCS) kind.
  • PAA polyacrylic acid PAA
  • PAAS sodium polyacrylate
  • PAM polyacryl
  • the negative electrode active material layer may optionally include other additives.
  • other additives may include thickeners such as sodium carboxymethylcellulose (CMC-Na), PTC thermistor materials, and the like.
  • CMC-Na sodium carboxymethylcellulose
  • PTC thermistor materials PTC thermistor materials, and the like.
  • the mass percentage of the other additives is ⁇ 2%.
  • the negative electrode current collector may use 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 and a metal material layer formed on at least one surface of the polymer material base.
  • the metal material may be selected from at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
  • the polymer material base layer can be selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), poly Ethylene (PE), etc.
  • the negative electrode active material 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 them evenly.
  • the solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.
  • the negative electrode sheet does not exclude other additional functional layers other than the negative active material layer.
  • the negative electrode sheet described in the present application also includes a conductive primer layer (such as Composed of conductive agent and binder).
  • the negative electrode sheet described in the present application further includes a protective layer covering the surface of the negative electrode active material layer.
  • the present application has no specific limitation on the type of the electrolyte, which can be selected according to requirements.
  • the electrolyte may be selected from at least one of solid electrolytes and liquid electrolytes (ie, electrolyte solutions).
  • the electrolyte is an electrolytic solution
  • the electrolytic solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), bis Lithium fluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), At least one of lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorodifluorooxalatephosphate (LiDFOP), lithium tetrafluorooxalatephosphate (LiPF 6 ), lithium tetrafluorooxalatephosphate (LiPF 6 ), lithium te
  • the solvent may include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate ( DMC), Dipropyl Carbonate (DPC), Methyl Propyl Carbonate (MPC), Ethyl Propyl 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), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EM
  • additives may optionally be included in the electrolyte.
  • the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and improve battery performance. Additives for low temperature power performance, etc.
  • Secondary batteries using electrolytes and some secondary batteries using solid electrolytes also include a separator.
  • the separator is arranged between the positive pole piece and the negative pole piece, mainly to prevent the short circuit of the positive and negative poles, and at the same time allow active ions to pass through.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film, or a multi-layer composite film. When the isolation film is a multilayer composite film, the materials of each layer are the same or different.
  • the positive electrode sheet, the separator, and the negative electrode sheet can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer package.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer package of the secondary battery may be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, and the like.
  • the outer packaging of the secondary battery may also be a soft bag, such as a pouch-type soft bag.
  • the material of the soft bag can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS) and the like.
  • FIG. 2 shows a secondary battery 5 with a square structure as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the housing 51 has an opening communicating with the receiving chamber, and the cover plate 53 is used to cover the opening to close the receiving chamber.
  • the positive pole piece, the negative pole piece and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the accommodating chamber. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or several, and can be adjusted according to requirements.
  • a positive pole piece, a separator, a negative pole piece and an electrolyte can be assembled to form a secondary battery.
  • the positive pole piece, the separator, and the negative pole piece can be formed into an electrode assembly through a winding process or a lamination process, and the electrode assembly is placed in an outer package, and after drying, the electrolyte is injected, and after vacuum packaging, standing, Formation, shaping and other processes to obtain secondary batteries.
  • the secondary battery according to the present application can be assembled into a battery module, and 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. 4 is a schematic diagram of a 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 may be fixed by fasteners.
  • the battery module 4 may also include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.
  • the above 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 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 is used to cover the lower box body 3 and forms a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the embodiments of the present application also provide an electric device, the electric device includes at least one of the secondary battery, the battery module, or the battery pack of the present application.
  • the secondary battery, battery module or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric device can be, but not limited to, mobile devices (such as mobile phones, notebook computers, 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 electric device can select a secondary battery, a battery module or a battery pack according to its usage requirements.
  • FIG. 7 is a schematic diagram of an example electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module can be used.
  • the electric device may be a mobile phone, a tablet computer, a notebook computer, and the like.
  • the electrical device is usually required to be light and thin, and a secondary battery can be used as a power source.
  • the polyfluorinated olefin resin prepared by the emulsion polymerization method was purchased from Arkema Company, and the polyfluorinated olefin resin prepared by the suspension polymerization method was purchased from Solvay Company.
  • the dispersion line speed is 22m/s, and the dispersion time is 60min; continue Add polyvinylidene fluoride (PVDF) resin with a number average molecular weight of 1,100,000, a crystallinity of 45%, and a melting point Tm of 172°C in a dispersed state
  • PVDF polyvinylidene fluoride
  • the dispersing line speed is 20m/s, and the dispersing time is 240min; finally, it is filtered through a 150-mesh filter to obtain the insulating slurry.
  • the mass percentage w1 of the resin is 3.8%
  • the mass percentage w2 of the inorganic filler is 21.2%
  • the mass percentage w3 of the organic solvent is 75.0 %.
  • the positive active material lithium iron phosphate, conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) in an appropriate amount of solvent NMP according to the mass ratio of 97:1:2 to form a uniform positive electrode slurry material; the positive electrode slurry and the above-mentioned insulating slurry are evenly coated on the surface of the positive electrode current collector aluminum foil according to the mode shown in Figure 1 with the same coating speed, and dried (dried to the content of NMP in the positive electrode sheet ⁇ 0.3 %), cold pressing, to obtain the positive electrode sheet.
  • the coating weight of the positive electrode slurry was 360 mg/1540.25 mm 2 , the coating width of the insulating slurry was 10 mm, and the coating speed was 60 m/min.
  • Negative active material graphite, binder styrene-butadiene rubber (SBR), thickener sodium carboxymethyl cellulose (CMC-Na), conductive agent carbon black (Super P) are mixed according to mass ratio 96.2:1.8:1.2:0.8 An appropriate amount of solvent is fully stirred and mixed in deionized water to form a uniform negative electrode slurry; the negative electrode slurry is evenly coated on the surface of the copper foil of the negative electrode current collector, and after drying and cold pressing, the negative electrode sheet is obtained.
  • SBR binder styrene-butadiene rubber
  • CMC-Na thickener sodium carboxymethyl cellulose
  • Super P conductive agent carbon black
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DMC dimethyl carbonate
  • a porous polyethylene film was used as the separator.
  • the preparation method of the secondary battery is similar to that of Example 1, except that the composition of the insulating paste is different, and the specific parameters are shown in Table 1.
  • the talcum powder or mica powder adopted in Examples 1 ⁇ 15, 19 ⁇ 21 and Comparative Example 3 are processed through pickling (mass fraction is 1% hydrochloric acid aqueous solution) and water washing, and the talcum powder adopted in Example 16 has not been pickled and washed. Washed treatment.
  • the preparation method of the secondary battery is similar to that of Example 1, except that the order of adding the insulating paste is different.
  • PVDF Polyvinylidene fluoride
  • the surface tension of the obtained insulating paste at 25° C. was measured by a DCAT9T surface tension tester of the German dataphysics company.
  • the positive pole pieces corresponding to each embodiment and comparative example were respectively measured by a CCD visual inspection device to measure the fuzzy width (that is, the maximum width) of the fusion zone on the positive pole piece.
  • the coating speed of the positive electrode slurry and the insulating slurry of Comparative Example 1 and Comparative Example 3 is 36m/min
  • the coating speed of the positive electrode slurry and insulating slurry of Comparative Example 2 is 45m/min
  • the embodiment The coating speeds of the positive electrode slurry and the insulating slurry of 1 to 21 were both 60 m/min.
  • Capacity retention (%) of the secondary battery after 500 cycles at 60°C discharge capacity of the 500th cycle/discharge capacity of the first cycle ⁇ 100%.
  • the secondary batteries prepared in each example and comparative example were charged to 3.65V at room temperature with a constant current of 1/3C; after being stored at 60 °C for 60 days, kept at room temperature for 5 hours, and discharged at a constant current of 1/3C to 2.50V , continue to charge to 3.65V with 1/3C constant current, and then discharge to 2.50V with 1/3C constant current to obtain the discharge capacity of the secondary battery after storage.
  • Capacity retention (%) of the secondary battery after storage at 60° C. for 60 days discharge capacity of the secondary battery after storage / rated capacity of the secondary battery ⁇ 100%.
  • Table 2 shows the performance test results of Examples 1-21 and Comparative Examples 1-4.
  • Fig. 8 is a comparison chart of the results of the insulating paste prepared in Example 1 and Comparative Example 1 under high-speed coating. As shown in Fig. 8, the technical solution of the insulating paste of the present application can effectively reduce the blur width of the fusion zone. From the test results in Table 2, it can be seen that the blur width of the fusion zone is only 0.4 mm at the coating speed of 60 m/min for the insulating slurry prepared in Example 1, while the insulating slurry prepared in Comparative Example 1 is coated at 36 m/min. The blur width of the fusion zone at cloth speed has reached 2.2mm.
  • the present application can limit the migration of the insulating slurry to the positive electrode slurry coating area by using the polyfluorinated olefin resin prepared by the suspension polymerization method in combination with the two-dimensional inorganic material, and can also improve the coating speed. while significantly reducing the blur width of the fusion zone.
  • Comparative Example 2 the combination of polyfluorinated olefin resin prepared by suspension polymerization and conventional spherical or spherical inorganic filler boehmite can increase the coating speed and reduce the blur width of the fusion zone to a certain extent, but the improvement effect is limited , the fuzzy width of the fusion zone has reached 1.0 mm at the coating speed of 45 m/min for the insulating paste. Therefore, it is difficult to use the insulating paste prepared in Comparative Example 2 at a coating speed of 60 m/min or more.
  • the combination of polyfluorinated olefin resin prepared by emulsion polymerization and two-dimensional inorganic materials can also increase the coating speed and reduce the blur width of the fusion zone to a certain extent, but the improvement effect is also limited.
  • the blur width of the fusion zone has reached 1.5 mm. Therefore, it is difficult to use the insulating slurry prepared in Comparative Example 3 at a coating speed above 60 m/min.
  • the resin was added first and then the inorganic filler was added, which resulted in the inability of uniform dispersion of the inorganic filler.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供一种绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及用电装置，所述绝缘浆料包括树脂、无机填料以及有机溶剂，其中，所述树脂选自悬浮聚合法制备的聚氟化烯烃树脂，所述无机填料选自二维无机材料。本申请能同时提升绝缘浆料的涂布速度和二次电池的安全性能。

Description

绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及用电装置 技术领域
本申请属于电池技术领域，具体涉及一种绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及用电装置。
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，其安全问题受到越来越多的关注，如果二次电池的安全问题不能保证，那该二次电池就无法使用。因此，如何增强二次电池的安全性能，是目前亟待解决的技术问题。
发明内容
本申请的目的在于提供一种绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及用电装置，旨在同时提升绝缘浆料的涂布速度和二次电池的安全性能。
本申请第一方面提供一种绝缘浆料，包括树脂、无机填料以及有机溶剂，其中，所述树脂选自悬浮聚合法制备的聚氟化烯烃树脂，所述无机填料选自二维无机材料。
在本申请的绝缘浆料的技术方案中，通过将悬浮聚合法制备的聚氟化烯烃树脂与二维无机材料组合使用，能够限制所述绝缘浆料向所述正极浆料涂布区域迁移，并且还能在提升涂布速度的同时显著降低融合区的模糊宽度，提高二次电池安全性能。本申请的绝缘浆料的技术方案还能保证二次电池具有高能量密度。由本申请的绝缘浆料制备的绝缘涂层能够同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性，即使是在负极活性材料层由于异物、毛刺等原因刺穿隔离膜接触到正极极片时，也不会使负极活性材料层和正极集流体直接接触，从而保证二次电池具有高安全性能。
在本申请的任意实施方式中，基于所述绝缘浆料的总质量计，所述树脂的质量百分含量w1为1％～5％，所述无机填料的质量百分含量w2为5％～35％，所述有机溶剂的质量百分含量w3为60％～94％。通过合理调节树脂、无机填料以及有机溶剂的质量百分含量，能够在显著提升涂布速度的同时，有效降低融合区的模糊宽度。此外，由此得到的绝缘涂层同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性，采用该绝缘涂层的二次电池能在具有良好的电化学性能的同时，具有更高的安全性能。
在本申请的任意实施方式中，w1/w2为0.05～1。可选地，w1/w2为0.1～1。w1/w2在合适的范围内时，能在有效降低融合区的模糊宽度的同时，保证绝缘涂层同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性。
在本申请的任意实施方式中，所述绝缘浆料在25℃下的粘度为1000cps～20000cps。可选地，所述绝缘浆料在25℃下的粘度为3000cps～8000cps。
在本申请的任意实施方式中，所述聚氟化烯烃树脂的数均分子量为600000～1500000。可选地，所述聚氟化烯烃树脂的数均分子量为1100000～1300000。
在本申请的任意实施方式中，所述聚氟化烯烃树脂的结晶度为30％～60％。可选地，所述聚氟化烯烃树脂的结晶度为40％～50％。
在本申请的任意实施方式中，所述聚氟化烯烃树脂的熔点为150℃～180℃。可选地，所述聚氟化烯烃树脂的熔点为155℃～175℃。
在本申请的任意实施方式中，所述聚氟化烯烃树脂选自聚偏氟乙烯树脂、聚氟乙烯树脂、聚四氟乙烯树脂、偏氟乙烯-六氟丙烯共聚物树脂、偏氟乙烯-三氟乙烯共聚物树脂、偏氟乙烯-三氟氯乙烯共聚物树脂、偏氟乙烯-四氟乙烯共聚物树脂、偏氟乙烯-四氟乙烯-六氟丙烯共聚物树脂中的至少一种。
在本申请的任意实施方式中，所述二维无机材料的形貌呈层状、薄片状或薄板状。
在本申请的任意实施方式中，所述二维无机材料选自层状硅酸盐、二维分子筛中的至少一种。层状硅酸盐和二维分子筛的形貌呈层状、薄片状或薄板状，当所述绝缘浆料向所述正极浆料涂布区域迁移时能够起到降低迁移速度的作用，从而降低融合区的模糊宽度。层状硅酸盐和二维分子筛还具有较强的吸附能力，能够与绝缘浆料中的树脂通过范德华力结合，从而进一步降低绝缘浆料的迁移速度和融合区的模糊宽度。
在本申请的任意实施方式中，所述层状硅酸盐包括云母粉、氟金云母粉、滑石粉、水滑石、类水滑石中的至少一种。
在本申请的任意实施方式中，所述二维分子筛包括MWW型、SAPO型、FER型、PLS-n型分子筛中的至少一种。
在本申请的任意实施方式中，所述二维无机材料的体积平均粒径Dv50为0.5μm～10μm。可选地，所述二维无机材料的体积平均粒径Dv50为0.5μm～5μm。
在本申请的任意实施方式中，所述二维无机材料的径厚比≥50:1。可选地，所述二维无机材料的径厚比为50:1～100:1。
在本申请的任意实施方式中，所述有机溶剂包括N-甲基吡咯烷酮、磷酸三乙酯、二甲基亚砜、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺中的至少一种。
在本申请的任意实施方式中，所述绝缘浆料中乳化剂的质量百分含量小于等于1/1000000。可选地，所述绝缘浆料中乳化剂的质量百分含量为0％。
本申请第二方面提供一种绝缘浆料的制备方法，包括以下步骤：S100，将有机溶剂和无机填料分散均匀，得到第一浆料；S200，在分散状态下向所得到的第一浆料中加入树脂粒子，分散均匀后得到绝缘浆料；其中，所述无机填料选自二维无机材料中的至少一种，所述树脂粒子选自悬浮聚合法制备的聚氟化烯烃树脂中的至少一种。
在本申请的任意实施方式中，基于所述绝缘浆料的总质量计，所述树脂粒子的质量百分含量为1％～5％，所述无机填料的质量百分含量为5％～35％，所述有机溶剂的质量百分含量为60％～94％。
在本申请的任意实施方式中，S100中，分散线速度为20m/s～100m/s，分散时间为15min～120min。
在本申请的任意实施方式中，S200中，分散线速度为20m/s～100m/s，分散时间为120min～480min。
在本申请的任意实施方式中，所述方法还包括：S300，过滤所得到的绝缘浆料。可选地，使用100～200目滤网过滤所得到的绝缘浆料。
在本申请的任意实施方式中，所述树脂粒子为一次颗粒。所述一次颗粒的体积平均粒径Dv50为20μm～150μm。可选地，所述一次颗粒的体积平均粒径Dv50为50μm～100μm。
本申请第三方面提供一种正极极片，包括正极集流体、正极活性材料层以及绝缘涂层，其中，所述正极活性材料层位于所述正极集流体至少部分表面，所述绝缘涂层位于所述正极集流体表面并且沿所述正极集流体长度方向与所述正极活性材料层边缘相接，其中，所述绝缘涂层为本申请第一方面所述的绝缘浆料经干燥形成的层、或通过本申请第二方面所述的方法制备的绝缘浆料干燥后形成的层。
在本申请的任意实施方式中，所述绝缘涂层的厚度为2μm～150μm。
在本申请的任意实施方式中，所述绝缘涂层的宽度为0.1mm～15mm。
本申请第四方面提供一种二次电池，其包括本申请第三方面的正极极片。
本申请第五方面提供一种电池模块，其包括本申请第四方面的二次电池。
本申请第六方面提供一种电池包，其包括本申请第四方面的二次电池、第五方面的电池模块中的一种。
本申请第七方面提供一种用电装置，其包括本申请第四方面的二次电池、第五方面的电池模块、第六方面的电池包中的至少一种。
[有益效果]
本申请的绝缘浆料将悬浮聚合法制备的聚氟化烯烃树脂与二维无机材料组合使用，能够限制所述绝缘浆料向所述正极浆料涂布区域迁移，并且还能在提升涂布速度的同时显著降低融合区的模糊宽度，提高二次电池安全性能。本申请的绝缘浆料还能保证二次电池具有高能量密度。由本申请的绝缘浆料制备的绝缘涂层能够同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性，即使是在负极活性材料层由于异物、毛刺等原因刺穿隔离膜接触到正极极片时，也不会使负极活性材料层和正极集流体直接接触，从而保证二次电池具有高安全性能。本申请的电池模块、电池包和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是本申请的正极极片的一实施方式的示意图。
图2是本申请的二次电池的一实施方式的示意图。
图3是图2的二次电池的实施方式的分解图。
图4是本申请的电池模块的一实施方式的示意图。
图5是本申请的电池包的一实施方式的示意图。
图6是图5所示的电池包的实施方式的分解图。
图7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。
图8是实施例1和对比例1制备的绝缘浆料在高速涂布下结果对比图。
在附图中，附图未必按照实际的比例绘制。
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绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及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“二维无机材料”是指形貌呈二维或近二维结构的无机材料，例如，无机材料的形貌呈层状、薄片状或薄板状。
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质，电极组件包括正极极片、负极极片和隔离膜。正极极片包括正极集流体和正极活性材料层，正极活性材料层涂布于正极集流体的表面，并且正极活性材料层包括正极活性材料。负极极片包括负极集流体和负极活性材料层，负极活性材料层涂布于负极集流体的表面，并且负极活性材料层包括负极活性材料。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使活性离子通过。电解质在正极极片和负极极片之间起到传导活性离子的作用。
安全问题是制约二次电池应用及推广的重要因素，其中，内短路是影响二次电池安全问题、甚至造成二次电池失效的主要原因。二次电池内短路形式主要包括以下四种：(1)负极集流体和正极集流体之间的短路；(2)负极活性材料层和正极活性材料层之间的短路；(3)负极活性材料层和正极集流体之间的短路；(4)正极活性材料层和负极集流体之间的短路。多数研究认为负极活性材料层和正极集流体之间的短路是最危险的，主要是因为负极活性材料层为电子的良导体，因此短路点的阻抗较小，短路后电压会急剧下降，电路点温度会急剧上升，最终可能引起燃烧、甚至爆炸。
为了提升二次电池的安全性能，通常采用的策略是对正极集流体表面紧邻正极活性材料层的区域进行绝缘处理，例如涂布一层绝缘涂层。但是，在正极极片烘干工序中，现有绝缘浆料会向正极浆料涂布区域迁移，从而烘干结束后会在正极活性材料层和绝缘涂层之间边界形成融合区(俗称虚边，即migration width of insulating coating to positive active material layer)，融合区的模糊宽度实际上是绝缘浆料向正极浆料涂布区域迁移的距离、或正极活性材料层被绝缘涂层覆盖区域的宽度。融合区的出现会导致激光模切过程中CCD(Charge Coupled Device)视觉检测设备定位困难、正极极片模切尺寸不准，甚至危及二次电池的Overhang，从而给二次电池带来严重的安全隐患。此外，融合区实际上是绝缘涂层成分与正极活性材料层成分相互融合形成的区域，或者是正极活性材料层被绝缘涂层覆盖形成的区域故融合区的离子传导性能通常较差，从而阻挡/阻碍部分活性离子的脱出和嵌入，因此，融合区的出现还会降低二次电池的能量密度，并且，融合区越宽，二次电池的能量密度下降越明显。另外，涂布速度越快，融合区越宽，甚至在高速涂布，例如涂布速度＞30m/min时，融合区的模糊宽度可能超过3mm。主要是因为，涂布速度越快，对应的烘干温度越高，高温下绝缘浆料的流动性更好、表面张力更低，从而更易向正极浆料涂布区域迁移。
随着二次电池的应用及推广，对涂布速度要求越来越高，因此，需要有效的技术手段在提升涂布速度的同时降低融合区的模糊宽度。
绝缘浆料
本申请实施方式的第一方面提供了一种绝缘浆料，包括树脂、无机填料以及有机溶剂，其中，所述树脂选自悬浮聚合法制备的聚氟化烯烃树脂，所述无机填料选自二维 无机材料。
聚氟化烯烃树脂由于具有优异的粘结力、耐电解液性、耐电化学氧化性等优点，目前广泛用于正极浆料和绝缘浆料。但是采用聚氟化烯烃树脂的绝缘浆料不可避免地向正极浆料涂布区域迁移，并且烘干结束后还会在正极活性材料层和绝缘涂层之间边界形成较宽的融合区；同时，涂布速度越快，融合区越宽，从而制约了涂布速度的提升。目前，技术人员一直没有找到融合区形成的根本原因，从而为了降低融合区的模糊宽度，保证二次电池具有高安全性能，现有技术通常采用的策略是降低涂布速度。
本申请的发明人经过大量研究意外发现，现有绝缘浆料容易形成较宽的融合区的原因在于，现有绝缘浆料采用乳液聚合法制备的聚氟化烯烃树脂。乳液聚合体系通常包括单体、乳化剂、引发剂和水4种基本成分，其中，乳化剂在乳液聚合体系中的作用包括：降低表面张力，使单体分散成细小的液滴；在液滴表面形成保护层，防止凝聚；增溶作用。采用乳液聚合法制备聚氟化烯烃树脂时一般采用含氟乳化剂，最常用的含氟乳化剂包括全氟辛酸(Pentadecafluorooctanoic acid，PFOA)及其碱金属盐、全氟丁基磺酸、全氟丁基磺酸盐、全氟聚醚、含氟聚醚酸及其盐(例如全氟聚醚羧酸、全氟聚醚羧酸铵)等。由于聚合工艺等原因，乳液聚合法制备的聚氟化烯烃树脂中的乳化剂难以清除，由此导致绝缘浆料的表面张力较低；此外，氟的电负性最大，具有强烈的吸电子性，C-F键能较高，由此当采用的乳化剂为含氟乳化剂时，其表面活性更高、表面张力更低，进而导致绝缘浆料的表面张力进一步降低，并且明显小于正极浆料的表面张力。因此，采用乳液聚合法制备的聚氟化烯烃树脂的绝缘浆料不可避免地形成较宽的融合区，制约了涂布速度的提升。
本申请的绝缘浆料采用悬浮聚合法制备的聚氟化烯烃树脂。悬浮聚合体系通常包括单体、分散剂、引发剂、链转移剂和水5种基本成分，其中分散剂的主要作用包括：吸附在单体液体表面，保持聚合体系的稳定；防止聚合物粒子之间发生聚并。采用悬浮聚合法制备聚氟化烯烃树脂时一般采用水溶性分散剂，例如纤维素醚和聚乙烯醇，与乳液聚合法相比，悬浮聚合法制备的聚氟化烯烃树脂粒子上吸附的分散剂较少，且容易清除，树脂纯度更高。
本申请的绝缘浆料不包含或基本不含乳化剂，其质量百分含量低于检出下限，例如≤1/1000000。因此，本申请采用悬浮聚合法制备的聚氟化烯烃树脂得到的绝缘浆料与现有绝缘浆料相比具有更高的表面张力，从而缩小了与正极浆料之间的表面张力差，进而本申请的绝缘浆料还能够降低融合区的模糊宽度。
在本申请的绝缘浆料的技术方案中，采用二维无机材料作为无机填料。当所述无机填料具有二维(或近二维)结构时，液体溶液(即所述树脂溶液)向所述正极浆料涂布区域扩散的路径变长、扩散的阻力变大。因此，采用二维无机材料作为无机填料能够降低所述绝缘浆料的迁移速度，限制所述绝缘浆料向所述正极浆料涂布区域迁移，从而进一步降低融合区的模糊宽度。
因此，在本申请的绝缘浆料的技术方案中，通过将悬浮聚合法制备的聚氟化烯烃树脂与二维无机材料组合使用，能够限制所述绝缘浆料向所述正极浆料涂布区域迁移，并且还能在提升涂布速度的同时显著降低融合区的模糊宽度，提高二次电池安全性能。本申请的技术方案在涂布速度为60m/min以上时，融合区的模糊宽度能够≤0.5mm，甚至 ≤0.2mm，显著优于行业平均水平(涂布速度在30m/min～40m/min时，融合区的模糊宽度＞2mm)。本申请的绝缘浆料的技术方案还能保证二次电池具有高能量密度。由本申请的绝缘浆料制备的绝缘涂层能够同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性，即使是在负极活性材料层由于异物、毛刺等原因刺穿隔离膜接触到正极极片时，也不会使负极活性材料层和正极集流体直接接触，从而保证二次电池具有高安全性能。
在一些实施例中，基于所述绝缘浆料的总质量计，所述树脂的质量百分含量w1可为1％，1.5％，2％，2.5％，3％，3.5％，4％，4.5％，5％或以上任何数值所组成的范围。可选地，所述树脂的质量百分含量w1为1％～5％，1.5％～5％，2％～5％，2.5％～5％，3％～5％，3.5％～5％，4％～5％，1％～4％，1.5％～4％，2％～4％，2.5％～4％，3％～4％，3.5％～4％，1％～3％，1.5％～3％，2％～3％，2.5％～3％，1％～2％，或1.5％～2％。
树脂的质量百分含量较高时，绝缘涂层的机械强度、耐热性和绝缘性较差，不能有效防止负极活性材料层和正极集流体直接接触，二次电池内短路风险增加，同时树脂的质量百分含量较高时，绝缘浆料的粘度通常较高，不易涂覆；树脂的质量百分含量较低时，绝缘涂层的粘结性和耐电解液性变差，容易从正极集流体上脱落，也不能保证二次电池长期使用时的安全性能。因此，树脂的质量百分含量在合适范围内时，绝缘涂层同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性，即使是在负极活性材料层由于异物、毛刺等原因刺穿隔离膜接触到正极极片时，也不会使负极活性材料层和正极集流体直接接触，从而保证二次电池长期使用时具有更高的安全性能。
在一些实施例中，基于所述绝缘浆料的总质量计，所述无机填料的质量百分含量w2可为5％，8％，10％，12％，14％，16％，18％，20％，22％，24％，26％，28％，30％，32％，35％或以上任何数值所组成的范围。可选地，所述无机填料的质量百分含量w2为5％～35％，10％～35％，15％～35％，20％～35％，25％～35％，30％～35％，5％～32％，10％～32％，15％～32％，20％～32％，25％～32％，5％～30％，10％～30％，15％～30％，20％～30％，25％～30％，5％～28％，10％～28％，15％～28％，20％～28％，25％～28％，5％～26％，10％～26％，15％～26％，20％～26％，5％～24％，10％～24％，15％～24％，20％～24％，5％～22％，10％～22％，15％～22％，5％～20％，10％～20％，或15％～20％。
无机填料的质量百分含量较高时，绝缘涂层的粘结性和耐电解液性变差，容易从正极集流体上脱落，不能保证二次电池长期使用时的安全性能；无机填料的质量百分含量较低时，绝缘涂层的机械强度、耐热性和绝缘性较差，不能有效防止负极活性材料层和正极集流体直接接触，二次电池内短路风险增加。因此，无机填料的质量百分含量在合适范围内时，绝缘涂层同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性，即使是在负极活性材料层由于异物、毛刺等原因刺穿隔离膜接触到正极极片时，也不会使负极活性材料层和正极集流体直接接触，从而保证二次电池长期使用时具有更高的安全性能。
在一些实施例中，基于所述绝缘浆料的总质量计，所述有机溶剂的质量百分含量w3可为60％，65％，70％，75％，80％，85％，90％，94％或以上任何数值所组成的范围。可选地，所述有机溶剂的质量百分含量w3为60％～94％，65％～94％，70％～94％，75％～94％，80％～94％，85％～94％，90％～94％，60％～90％，65％～90％，70％～90％， 75％～90％，80％～90％，85％～90％，60％～85％，65％～85％，70％～85％，75％～85％，80％～85％，60％～80％，65％～80％，70％～80％，75％～80％，60％～75％，65％～75％，70％～75％，60％～70％，或65％～70％。
在一些实施例中，基于所述绝缘浆料的总质量计，所述树脂的质量百分含量w1为1％～5％，所述无机填料的质量百分含量w2为5％～35％，所述有机溶剂的质量百分含量w3为60％～94％。通过合理调节树脂、无机填料以及有机溶剂的质量百分含量，能够在显著提升涂布速度的同时，有效降低融合区的模糊宽度。此外，由此得到的绝缘涂层同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性，采用该绝缘涂层的二次电池能在具有良好的电化学性能的同时还具有更高的安全性能。
w1/w2较小时，无机填料的质量百分含量较高，绝缘涂层的粘结性和耐电解液性较差；w1/w2较大时，无机填料的质量百分含量较少，不能有效阻挡所述树脂溶液向所述正极浆料涂布区域迁移，进而融合区容易变宽。w1/w2在合适的范围内时，能在有效降低融合区的模糊宽度的同时，保证绝缘涂层同时具有高机械强度、高耐热性、高绝缘性、高粘结性和优异的耐电解液性。在一些实施例中，w1/w2为0.05～1。可选地，w1/w2为0.1～1，0.12～1，0.15～1，或0.18～1。
绝缘浆料的粘度主要影响绝缘浆料的涂覆性能，粘度过大时会导致绝缘浆料无法涂布在正极集流体表面；同时绝缘浆料的粘度也不宜过小，此时绝缘浆料的流动性较强，进而融合区容易变宽。在一些实施例中，所述绝缘浆料在25℃下的粘度为1000cps～20000cps。例如，所述绝缘浆料在25℃下的粘度为1000cps，2000cps，3000cps，4000cps，5000cps，6000cps，7000cps，8000cps，9000cps，10000cps，11000cps，12000cps，13000cps，14000cps，15000cps，16000cps，17000cps，18000cps，19000cps，20000cps或以上任何数值所组成的范围。可选地，所述绝缘浆料在25℃下的粘度为2000cps～20000cps，4000cps～20000cps，6000cps～20000cps，8000cps～20000cps，10000cps～20000cps，12000cps～20000cps，14000cps～20000cps，16000cps～20000cps，18000cps～20000cps，1000cps～15000cps，2000cps～15000cps，4000cps～15000cps，6000cps～15000cps，8000cps～15000cps，10000cps～15000cps，12000cps～15000cps，1000cps～10000cps，2000cps～10000cps，4000cps～10000cps，6000cps～10000cps，8000cps～10000cps，1000cps～8000cps，2000cps～8000cps，3000cps～8000cps，4000cps～8000cps，5000cps～8000cps，6000cps～8000cps，1000cps～5000cps，2000cps～5000cps，3000cps～5000cps，或4000cps～5000cps。
考虑到所述绝缘涂层需要同时具有优异的粘结性和优异的耐电解液性，所述聚氟化烯烃树脂可以具有中等的分子量。在一些实施例中，所述聚氟化烯烃树脂的数均分子量为600000～1500000。可选地，所述聚氟化烯烃树脂的数均分子量为1100000～1300000。
考虑到所述绝缘涂层需要同时具有优异的粘结性和优异的耐电解液性，同时考虑所述正极极片的加工性能，所述聚氟化烯烃树脂可以具有中等的结晶度。所述聚氟化烯烃树脂的结晶度较低时，其在电解液中的溶胀度较高，绝缘涂层的耐电解液性变差，二次电池长期使用时容易从正极集流体上脱落；所述聚氟化烯烃树脂的结晶度较高时，由此制备的正极极片的加工性能变差，卷绕时易断带。在一些实施例中，所述聚氟化烯烃树脂的结晶度为30％～60％。可选地，所述聚氟化烯烃树脂的结晶度为40％～50％。
考虑到所述绝缘涂层需要同时具有优异的粘结性和优异的耐电解液性，同时考虑所述正极极片的加工性能，所述聚氟化烯烃树脂可以具有中等的熔点。所述聚氟化烯烃树脂的熔点较低时，其在电解液中的溶胀度较高，绝缘涂层的耐电解液性变差，二次电池长期使用时容易从正极集流体上脱落；所述聚氟化烯烃树脂的熔点较高时，由此制备的正极极片的加工性能变差，卷绕时易断带。在一些实施例中，所述聚氟化烯烃树脂的熔点T m为150℃～180℃。可选地，所述聚氟化烯烃树脂的熔点为155℃～175℃。
在一些实施例中，所述悬浮聚合法制备的聚氟化烯烃树脂选自聚偏氟乙烯(PVDF)树脂、聚氟乙烯树脂、聚四氟乙烯树脂、偏氟乙烯-六氟丙烯共聚物(VDF-HFP)树脂、偏氟乙烯-三氟乙烯共聚物树脂、偏氟乙烯-三氟氯乙烯共聚物树脂、偏氟乙烯-四氟乙烯共聚物树脂、偏氟乙烯-四氟乙烯-六氟丙烯共聚物树脂中的至少一种。
所述悬浮聚合法制备的聚氟化烯烃树脂可以购自Solvay公司或吴羽公司等，当然，所述悬浮聚合法制备的聚氟化烯烃树脂也可以通过合成得到。作为示例，所述悬浮聚合法制备的聚氟化烯烃树脂包括商购的
Figure PCTCN2021142341-appb-000001
Figure PCTCN2021142341-appb-000002
Figure PCTCN2021142341-appb-000003
中的至少一种。
在一些实施例中，所述二维无机材料的形貌呈层状、薄片状或薄板状。
在一些实施例中，所述二维无机材料的材质选自层状硅酸盐、二维分子筛中的至少一种。所述层状硅酸盐和所述二维分子筛的形貌呈二维或近二维结构，例如呈层状、薄片状或薄板状。
层状硅酸盐的晶体结构是由结构单元层(或晶层)相互平行叠置而成的。结构单元层包括片层和层间物两个部分，片层通常是由硅-氧四面体片(Tetrahedral sheet)和金属阳离子(例如，Mg 2+、Fe 2+、Al 3+等)-氧八面体片(Octohedral sheet)按1:1或2:1方式构成。片层之间为层间物，层间物可以是空的，也可以填充水分子、阳离子、阴离子等。二维分子筛是一种结晶态的铝硅酸盐，其空间网络结构是由硅-氧四面体和铝-氧四面体交错排列而成。
本申请中采用的层状硅酸盐和二维分子筛的形貌呈层状、薄片状或薄板状，当所述绝缘浆料向所述正极浆料涂布区域迁移时，上述无机填料能够增加所述液体溶液(即所述树脂溶液)向所述正极浆料涂布区域扩散的路径和扩散的阻力，从而起到降低绝缘浆料迁移速度的作用，进而降低了融合区的模糊宽度。层状硅酸盐和二维分子筛还具有较强的吸附能力，能够与绝缘浆料中的树脂通过范德华力结合，从而进一步降低绝缘浆料的迁移速度和融合区的模糊宽度。
层状硅酸盐和二维分子筛均具有热稳定性好、成本低廉的优势，同时还具有类似石墨的片层结构，并且层间结构的范德华力远小于层内的离子力，当受到挤压时能够发生层间滑动。因此，采用上述无机填料的绝缘涂层具有更优异的耐热性和绝缘性，从而能进一步提升二次电池的安全性能。此外，层状硅酸盐和二维分子筛还具有良好的韧性，从而由此制备的正极极片具有良好的加工性能，卷绕时不易断带。
可选地，所述层状硅酸盐包括云母粉、氟金云母粉、滑石粉、水滑石、类水滑石中的至少一种。
可选地，所述二维分子筛包括MWW型、SAPO型、FER型、PLS-n型分子筛中 的至少一种。作为示例，所述二维分子筛包括MCM-22、MCM-49、MCM-56、SAPO-34、SAPO-18、Al-PLS-3中的至少一种。
在一些实施例中，当所述绝缘浆料包括云母粉、滑石粉中的至少一种时，可预先通过酸洗和水洗工艺除去云母粉、滑石粉中的一些过渡金属杂质。这些过渡金属杂质可能会妨碍二次电池电化学性能的发挥，例如增加二次电池的自放电等。本申请对酸洗和水洗的次数没有特别的限制，可根据实际需求进行选择。酸洗时优选使用弱酸水溶液，例如硼酸水溶液等，当然也可以选择强酸的稀溶液，例如质量分数为1％左右的硝酸、硫酸或盐酸水溶液。
在一些实施例中，所述二维无机材料的体积平均粒径Dv50为0.5μm～10μm。例如，所述二维无机材料的体积平均粒径Dv50为0.5μm，1μm，2μm，3μm，4μm，5μm，6μm，7μm，8μm，9μm，10μm或以上任何数值所组成的范围。可选地，所述二维无机材料的体积平均粒径Dv50为0.5μm～9μm，0.5μm～8μm，0.5μm～7μm，0.5μm～6μm，0.5μm～5μm，0.5μm～4μm，0.5μm～3μm，1μm～10μm，1μm～9μm，1μm～8μm，1μm～7μm，1μm～6μm，1μm～5μm，1μm～4μm，或1μm～3μm。
所述二维无机材料的形貌呈层状、薄片状或薄板状，因此，所述二维无机材料通常具有较高的径厚比(diameter-thickness ratio)。当所述二维无机材料的径厚比较小时，其降低所述绝缘浆料迁移速度的作用较弱，从而融合区的模糊宽度会稍增加。在一些实施例中，所述二维无机材料的径厚比可以≥30:1，≥40:1，≥50:1，≥60:1，≥70:1，≥80:1，≥90:1，≥100:1，≥110:1，≥120:1，≥130:1，≥140:1，≥150:1。所述二维无机材料的径厚比越大，其降低所述绝缘浆料迁移速度的作用越明显，但是所述二维无机材料的制造成本增加。在一些实施例中，可选地，所述二维无机材料的径厚比为50:1～150:1，50:1～140:1，50:1～130:1，50:1～120:1，50:1～110:1，50:1～100:1，50:1～90:1，或50:1～80:1。
本申请对所述有机溶剂的种类没有特别的限制，可以采用本领域公知的能够溶解所述树脂的化合物。在一些实施例中，所述有机溶剂包括N-甲基吡咯烷酮(NMP)、磷酸三乙酯、二甲基亚砜、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺中的至少一种。
在一些实施例中，所述绝缘浆料包括树脂、无机填料以及有机溶剂，所述树脂选自悬浮聚合法制备的聚氟化烯烃树脂，所述无机填料选自二维无机材料；基于所述绝缘浆料的总质量计，所述树脂的质量百分含量w1为1％～5％，所述无机填料的质量百分含量w2为5％～35％，所述有机溶剂的质量百分含量w3为60％～94％；所述悬浮聚合法制备的聚氟化烯烃树脂选自聚偏氟乙烯树脂、聚氟乙烯树脂、聚四氟乙烯树脂、偏氟乙烯-六氟丙烯共聚物树脂、偏氟乙烯-三氟乙烯共聚物树脂、偏氟乙烯-三氟氯乙烯共聚物树脂、偏氟乙烯-四氟乙烯共聚物树脂、偏氟乙烯-四氟乙烯-六氟丙烯共聚物树脂中的至少一种；所述二维无机材料的形貌呈层状、薄片状或薄板状；所述二维无机材料的径厚比≥50:1；所述二维无机材料的材质选自层状硅酸盐、二维分子筛中的至少一种。
在本申请中，树脂的数均分子量为本领域公知的含义，可以用本领域公知的仪器及方法进行测定。例如可以采用凝胶渗透色谱法(GPC)进行测定，测试可采用安捷伦(Agilent)1290 Infinity II GPC系统。
在本申请中，树脂的结晶度为本领域公知的含义，可以用本领域公知的仪器及方法进行测定。例如可以采用差示扫描量热法(DSC)进行测定，测试可采用梅特勒-托利 多(Mettler-Toledo)的DSC-3型差示扫描量热仪。
在本申请中，树脂的熔点为本领域公知的含义，可以用本领域公知的仪器及方法进行测定。例如可以参考GB/T 29611-2013《生橡胶玻璃化转变温度的测定差示扫描量热法(DSC)》进行测定，测试可采用梅特勒-托利多(Mettler-Toledo)的DSC-3型差示扫描量热仪。
在本申请中，绝缘浆料的粘度为本领域公知的含义，可以用本领域公知的仪器及方法进行测定。例如可以参考GB/T 2794-2013《胶黏剂粘度的测定单圆筒旋转粘度计法》进行测定。
在本申请中，材料的体积平均粒径Dv50为本领域公知的含义，其表示累计体积分布百分数达到50％时所对应的粒径，可以用本领域公知的仪器及方法进行测定。例如可以参照GB/T 19077-2016粒度分布激光衍射法，采用激光粒度分析仪方便地测定，如英国马尔文仪器有限公司的Mastersizer 2000E型激光粒度分析仪。
在本申请中，二维无机材料的径厚比为本领域公知的含义，可以用本领域公知的仪器及方法进行测定。例如可以参考JC/T 2063-2011《云母粉径厚比测定方法》进行测定。
绝缘浆料的制备方法
本申请实施方式的第二方面提供了一种绝缘浆料的制备方法，包括以下步骤：S100，将有机溶剂和无机填料分散均匀，得到第一浆料；S200，在分散状态下向所得到的第一浆料中加入树脂粒子，分散均匀后得到绝缘浆料；其中，所述无机填料选自二维无机材料中的至少一种，所述树脂粒子选自悬浮聚合法制备的聚氟化烯烃树脂中的至少一种。
在一些实施例中，基于所述绝缘浆料的总质量计，所述树脂粒子的质量百分含量为1％～5％，所述无机填料的质量百分含量为5％～30％，所述有机溶剂的质量百分含量为65％～94％。
所述树脂粒子采用悬浮聚合法制备的聚氟化烯烃树脂，因此所述树脂粒子的粒径通常较大并且不易团聚。在一些实施例中，所述树脂粒子为一次颗粒形式。可选地，所述一次颗粒的体积平均粒径Dv50为20μm～150μm。例如，所述一次颗粒的体积平均粒径Dv50为20μm，30μm，40μm，50μm，60μm，70μm，80μm，90μm，100μm，110μm，120μm，130μm，140μm，150μm或以上任何数值所组成的范围。可选地，所述一次颗粒的体积平均粒径Dv50为30μm～150μm，50μm～150μm，70μm～150μm，90μm～150μm，20μm～120μm，30μm～120μm，50μm～120μm，70μm～120μm，90μm～120μm，20μm～100μm，30μm～100μm，50μm～100μm，70μm～100μm，20μm～80μm，30μm～80μm，或50μm～80μm。
在一些实施例中，S100中，分散线速度为20m/s～100m/s，分散时间为15min～120min。
在一些实施例中，S200中，分散线速度为20m/s～100m/s，分散时间为120min～480min。
在一些实施例中，所述方法还包括：S300，过滤所得到的绝缘浆料。可选地，使用100～200目滤网过滤所得到的绝缘浆料。
本申请实施方式的第二方面的绝缘浆料的制备方法能够制备本申请实施方式第一 方面的绝缘浆料。需要说明的是，通过本申请实施方式的第二方面的绝缘浆料的制备方法制备出的绝缘浆料的相关参数，可参见本申请实施方式第一方面各实施例提供的绝缘浆料。
正极极片
本申请实施方式的第三方面提供了一种正极极片，包括正极集流体、正极活性材料层以及绝缘涂层，其中，所述正极活性材料层位于所述正极集流体至少部分表面，所述绝缘涂层位于所述正极集流体表面并且沿所述正极集流体长度方向与所述正极活性材料层边缘相接，所述绝缘涂层为根据本申请实施方式第一方面任一实施例所述的绝缘浆料经干燥形成的层，或通过本申请实施方式第二方面任一实施例所述的方法制备的绝缘浆料干燥后形成的层。
本申请的正极极片能够降低负极活性材料层和正极集流体直接接触的概率，保证二次电池具有高安全性能。本申请的正极极片还具有良好的加工性能，卷绕时不易断带。
在一些实施例中，所述绝缘涂层位于所述正极活性材料层沿长度方向的一侧或两侧。可选地，所述绝缘涂层位于所述正极活性材料层沿长度方向的两侧。图1为本申请的正极极片的一实施方式的示意图。如图1所示，所述正极极片包括正极集流体101、正极活性材料层102和绝缘涂层103，绝缘涂层103位于正极活性材料层102沿长度方向L的两侧，但本申请不限于此。
本申请对所述绝缘涂层的厚度没有特别的限制，可根据实际需求进行调节。在一些实施例中，所述绝缘涂层的厚度为2μm～150μm。
本申请对所述绝缘涂层的宽度没有特别的限制，可根据实际需求进行调节。在一些实施例中，所述绝缘涂层的宽度为0.1mm～15mm。
在一些实施例中，所述正极集流体具有在自身厚度方向相对的两个表面，所述正极活性材料层设置于所述正极集流体的两个相对表面中的任意一者或两者上。
在一些实施例中，所述正极集流体具有在自身厚度方向相对的两个表面，所述绝缘涂层设置于所述正极集流体的两个相对表面中的任意一者或两者上。
所述正极活性材料层包括正极活性材料，所述正极活性材料可采用本领域公知的用于二次电池的正极活性材料。例如，所述正极活性材料可包括锂过渡金属氧化物、橄榄石结构的含锂磷酸盐及其各自的改性化合物中的至少一种。锂过渡金属氧化物的示例可包括锂钴氧化物、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改性化合物中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括磷酸铁锂、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。本申请并不限定于这些材料，还可以使用其他可被用作二次电池正极活性材料的传统公知的材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。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、或表面包覆改性。
在一实施例中，所述正极活性材料包括橄榄石结构的含锂磷酸盐及其改性化合物中的至少一种。
在一些实施例中，所述正极活性材料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、碳纳米纤维中的至少一种。在一些实施例中，基于所述正极活性材料层的总质量，所述正极导电剂的质量百分含量≤5％。
在一些实施例中，所述正极活性材料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、含氟丙烯酸酯类树脂中的至少一种。在一些实施例中，基于所述正极活性材料层的总质量，所述正极粘结剂的质量百分含量≤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。复合集流体可包括高分子材料基层以及形成于高分子材料基层至少一个表面上的金属材料层。作为示例，金属材料可选自铝、铝合金、镍、镍合金、钛、钛合金、银、银合金中的至少一种。作为示例，高分子材料基层可选自聚丙烯(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)、聚乙烯(PE)等。
所述正极活性材料层通常是将正极浆料涂布在正极集流体上，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。
本申请的正极极片的制备方法是公知的。在一些实施例中，可将正极浆料和本申请实施方式第一方面任一实施例所述的绝缘浆料涂布在正极集流体上，经干燥、冷压而成。
二次电池
本申请实施方式的第四方面提供了一种二次电池，包括正极极片、负极极片以及电解质。在二次电池充放电过程中，活性离子在所述正极极片和所述负极极片之间往返嵌入和脱出，所述电解质在所述正极极片和所述负极极片之间起到传导活性离子的作用。
[正极极片]
本申请的二次电池中使用的正极极片为本申请实施方式第三方面任一实施例所述的正极极片。
[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活性材料层。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，所述负极活性材料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、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、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、锡合金材料中的至少一种。本申请并不限定于这些材料，还可以使用其他可被用作二次电池负极 活性材料的传统公知的材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施例中，所述负极活性材料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、碳纳米纤维中的至少一种。在一些实施例中，基于所述负极活性材料层的总质量，所述负极导电剂的质量百分含量≤5％。
在一些实施例中，所述负极活性材料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)、羧甲基壳聚糖(CMCS)中的至少一种。在一些实施例中，基于所述负极活性材料层的总质量，所述负极粘结剂的质量百分含量≤5％。
在一些实施例中，所述负极活性材料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-Na)、PTC热敏电阻材料等。在一些实施例中，基于所述负极活性材料层的总质量，所述其他助剂的质量百分含量≤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。复合集流体可包括高分子材料基层以及形成于高分子材料基层至少一个表面上的金属材料层。作为示例，金属材料可选自铜、铜合金、镍、镍合金、钛、钛合金、银、银合金中的至少一种。作为示例，高分子材料基层可选自聚丙烯(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)、聚乙烯(PE)等。
所述负极活性材料层通常是将负极浆料涂布在负极集流体上，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活性材料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活性材料层之间、设置于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活性材料层表面的保护层。
[电解质]
本申请对所述电解质的种类没有具体的限制，可根据需求进行选择。例如，所述电解质可以选自固态电解质及液态电解质(即电解液)中的至少一种。
在一些实施例中，所述电解质采用电解液，所述电解液包括电解质盐和溶剂。
所述电解质盐的种类不受具体的限制，可根据实际需求进行选择。在一些实施例中，作为示例，所述电解质盐可包括六氟磷酸锂(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)、四氟草酸磷酸 锂(LiTFOP)中的至少一种。
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。在一些实施例中，作为示例，所述溶剂可包括碳酸乙烯酯(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)、氟代碳酸亚乙酯(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)及二乙砜(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。
[隔离膜]
采用电解液的二次电池、以及一些采用固态电解质的二次电池中，还包括隔离膜。所述隔离膜设置在所述正极极片和所述负极极片之间，主要起到防止正负极短路的作用，同时可以使活性离子通过。本申请对所述隔离膜的种类没有特别的限制，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多孔结构隔离膜。
在一些实施例中，所述隔离膜的材质可以包括玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。所述隔离膜可以是单层薄膜，也可以是多层复合薄膜。当所述隔离膜为多层复合薄膜时，各层的材料相同或不同。
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质。
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)、聚丁二酸丁二醇酯(PBS)等中的至少一种。
本申请对所述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2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3所示，外包装可包括壳体51和盖板53。其中，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几个，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4是作为一个示例的电池模块4的示意图。如图4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5和图6是作为一个示例的电池包1的示意图。如图5和图6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
本申请实施方式还提供一种用电装置，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7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。
其中，乳液聚合法制备的聚氟化烯烃树脂均购自阿科玛公司，悬浮聚合法制备的聚氟化烯烃树脂均购自Solvay公司。
实施例1
绝缘浆料的制备
将体积平均粒径Dv50为2μm、径厚比为100:1的经酸洗和水洗除杂后的滑石粉加 入有机溶剂NMP中分散均匀，分散线速度为22m/s，分散时间为60min；继续在分散状态下加入数均分子量为1100000、结晶度为45％、熔点T m为172℃的聚偏氟乙烯(PVDF)树脂
Figure PCTCN2021142341-appb-000004
分散线速度为20m/s，分散时间为240min；最后使用150目滤网过滤，即得到绝缘浆料。基于所述绝缘浆料的总质量计，所述树脂的质量百分含量w1为3.8％，所述无机填料的质量百分含量w2为21.2％，所述有机溶剂的质量百分含量w3为75.0％。
正极极片的制备
将正极活性材料磷酸铁锂、导电剂炭黑(Super P)、粘结剂聚偏氟乙烯(PVDF)按照质量比97:1:2在适量的溶剂NMP中充分搅拌混合，形成均匀的正极浆料；将正极浆料和上述绝缘浆料按照图1所示的方式以同样的涂布速度均匀涂布于正极集流体铝箔的表面上，经干燥(干燥至正极极片中NMP的含量＜0.3％)、冷压后，得到正极极片。正极浆料的涂布重量为360mg/1540.25mm 2，绝缘浆料的涂布宽度为10mm，涂布速度60m/min。
负极极片的制备
将负极活性材料石墨、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC-Na)、导电剂炭黑(Super P)按照质量比96.2:1.8:1.2:0.8在适量的溶剂去离子水中充分搅拌混合，形成均匀的负极浆料；将负极浆料均匀涂布于负极集流体铜箔的表面上，经干燥、冷压后，得到负极极片。
电解液的制备
将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)按照体积比1:1:1进行混合得到有机溶剂，接着将充分干燥的LiPF 6溶解于上述有机溶剂中，配制成浓度为1mol/L的电解液。
隔离膜的制备
采用多孔聚乙烯膜作为隔离膜。
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2～21和对比例1～3
二次电池的制备方法与实施例1类似，不同之处在于绝缘浆料的组成不同，具体参数详见表1。其中，实施例1～15、19～21和对比例3采用的滑石粉或云母粉经过酸洗(质量分数为1％盐酸水溶液)和水洗处理，实施例16采用的滑石粉未经过酸洗和水洗处理。
对比例4
二次电池的制备方法与实施例1类似，不同之处在于绝缘浆料的加料顺序不同。
将数均分子量为1100000、结晶度为45％、熔点T m为172℃的聚偏氟乙烯(PVDF)树脂
Figure PCTCN2021142341-appb-000005
加入有机溶剂NMP中分散均匀，分散线速度为22m/s，分散时间为60min；继续在分散状态下加入体积平均粒径Dv50为2μm、径厚比为100:1的经酸洗和水洗除杂后的滑石粉，分散线速度为20m/s，分散时间为240min；最后使用150目滤网过滤，即得到绝缘浆料。基于所述绝缘浆料的总质量计，所述树脂的质量百分含量w1 为3.8％，所述无机填料的质量百分含量w2为21.2％，所述有机溶剂的质量百分含量w3为75.0％。
测试部分
(1)绝缘浆料的粘度测试
参考GB/T 2794-2013《胶黏剂粘度的测定单圆筒旋转粘度计法》测定所得到的绝缘浆料的粘度。测试温度为25℃，测试仪器采用美国博勒飞公司的Brookfield DVS+型旋转粘度计。
(2)绝缘浆料的表面张力测试
采用德国dataphysics公司的DCAT9T型表面张力测试仪测定所得到的绝缘浆料在25℃下的表面张力。
(3)绝缘浆料的高速涂布结果分析
将各实施例和对比例对应的正极极片分别通过CCD视觉检测设备测量正极极片上融合区的模糊宽度(即最大宽度)。其中，对比例1和对比例3的正极浆料和绝缘浆料的涂布速度均为36m/min，对比例2的正极浆料和绝缘浆料的涂布速度均为45m/min，实施例1～21的正极浆料和绝缘浆料的涂布速度均为60m/min。
(4)绝缘涂层的耐电解液性测试
将各实施例和对比例对应的正极极片分别于常温下浸泡于上述标准电解液中168h，之后在手套箱内除去标准电解液，并以棉签反复擦拭绝缘涂层，直至绝缘涂层掉落。其中，棉签擦拭次数越多，绝缘涂层的耐电解液性越好。
(5)绝缘涂层的粘结性测试
将各实施例和对比例制备的二次电池在60℃下以1C恒流充电至3.65V，然后在3.65V下恒压充电至电流≤0.05mA；静置5min后，以1C恒流放电至2.50V，此为一个循环充放电过程。将二次电池按照上述方法进行500次循环充放电测试后，拆解二次电池观察绝缘涂层是否从正极集流体脱落。
(6)二次电池K值测试
将各实施例和对比例制备的二次电池常温静置48h后，测试开路电压并记为OCV1；将二次电池在常温下继续静置48h后，测试开路电压并记为OCV2。二次电池的K值(mV/h)＝(OCV1-OCV2)/48。
(7)二次电池高温循环性能测试
将各实施例和对比例制备的二次电池在60℃下以1C恒流充电至3.65V，然后在3.65V下恒压充电至电流≤0.05mA；静置5min后，以1C恒流放电至2.50V，此为一个循环充放电过程。将二次电池按照上述方法进行500次循环充放电测试后，测定容量保持率。
二次电池60℃循环500次后容量保持率(％)＝第500次循环的放电容量/第1次循环的放电容量×100％。
(8)二次电池的高温存储性能测试
将各实施例和对比例制备的二次电池在常温下以1/3C恒流充电至3.65V；之后经60℃存储60天后，在常温下保持5h，以1/3C恒流放电至2.50V，继续以1/3C恒流充电至3.65V，再以1/3C恒流放电至2.50V，得到二次电池存储后的放电容量。
二次电池60℃存储60天后容量保持率(％)＝二次电池存储后的放电容量/二次电池的额定容量×100％。
表2给出实施例1～21和对比例1～4的性能测试结果。
图8是实施例1和对比例1制备的绝缘浆料在高速涂布下结果对比图，如图8所示，本申请的绝缘浆料的技术方案能够有效降低融合区的模糊宽度。从表2的测试结果可以看出，实施例1制备的绝缘浆料在60m/min涂布速度下融合区的模糊宽度仅为0.4mm，而对比例1制备的绝缘浆料在36m/min涂布速度下融合区的模糊宽度已达到2.2mm。因此，本申请通过将悬浮聚合法制备的聚氟化烯烃树脂与二维无机材料组合使用，能够限制所述绝缘浆料向所述正极浆料涂布区域迁移，并且还能在提升涂布速度的同时显著降低融合区的模糊宽度。
对比例2将悬浮聚合法制备的聚氟化烯烃树脂与常规球形或类球形的无机填料勃姆石组合使用，能够在一定程度上提升涂布速度并降低融合区的模糊宽度，但是改善效果有限，绝缘浆料在45m/min涂布速度下融合区的模糊宽度已达到1.0mm，因此，对比例2制备的绝缘浆料难以在60m/min以上涂布速度下使用。对比例3将乳液聚合法制备的聚氟化烯烃树脂与二维无机材料组合使用，也能够在一定程度上提升涂布速度并降低融合区的模糊宽度，但是改善效果也有限，绝缘浆料在36m/min涂布速度下融合区的模糊宽度已达到1.5mm，因此，对比例3制备的绝缘浆料也难以在60m/min以上涂布速度下使用。对比例4在制备绝缘浆料时，先加入树脂后加入无机填料，导致无机填料无法均匀分散。
从表2的测试结果还可以看出，通过合理调节树脂、无机填料以及有机溶剂的质量百分含量，使其满足w1为1％～5％，w2为5％～35％，w3为60％～94％时，能够进一步降低正极极片的融合区的模糊宽度。此外，在此基础上通过进一步合理调节树脂以及无机填料的质量比使w1/w2控制在0.1至1之间时，绝缘涂层能具有更高的粘结性和耐电解液性。
从实施例1、19～21的测试结果还可以看出，二维无机材料的径厚比越高，降低绝缘浆料迁移速度的作用较明显，正极极片融合区的模糊宽度越小。
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 PCTCN2021142341-appb-000006
Figure PCTCN2021142341-appb-000007

Claims (20)

  1. 一种绝缘浆料，包括树脂、无机填料以及有机溶剂，其中，
    所述树脂选自悬浮聚合法制备的聚氟化烯烃树脂，所述无机填料选自二维无机材料，
    可选地，所述二维无机材料的形貌呈层状、薄片状或薄板状。
  2. 根据权利要求1所述的绝缘浆料，其中，
    基于所述绝缘浆料的总质量计，所述树脂的质量百分含量w1为1％～5％，所述无机填料的质量百分含量w2为5％～35％，所述有机溶剂的质量百分含量w3为60％～94％；
    可选地，w1/w2为0.05～1，可选地为0.1～1。
  3. 根据权利要求1或2所述的绝缘浆料，其中，所述绝缘浆料在25℃下的粘度为1000cps～20000cps，可选地为3000cps～8000cps。
  4. 根据权利要求1-3中任一项所述的绝缘浆料，其中，
    所述聚氟化烯烃树脂的数均分子量为600000～1500000，可选地为1100000～1300000；和/或，
    所述聚氟化烯烃树脂的结晶度为30％～60％，可选地为40％～50％；和/或，
    所述聚氟化烯烃树脂的熔点为150℃～180℃，可选地为155℃～175℃。
  5. 根据权利要求4所述的绝缘浆料，其中，所述聚氟化烯烃树脂选自聚偏氟乙烯树脂、聚氟乙烯树脂、聚四氟乙烯树脂、偏氟乙烯-六氟丙烯共聚物树脂、偏氟乙烯-三氟乙烯共聚物树脂、偏氟乙烯-三氟氯乙烯共聚物树脂、偏氟乙烯-四氟乙烯共聚物树脂、偏氟乙烯-四氟乙烯-六氟丙烯共聚物树脂中的至少一种。
  6. 根据权利要求1-5中任一项所述的绝缘浆料，其中，所述二维无机材料选自层状硅酸盐、二维分子筛中的至少一种；
    可选地，所述层状硅酸盐包括云母粉、氟金云母粉、滑石粉、水滑石、类水滑石中的至少一种；
    可选地，所述二维分子筛包括MWW型、SAPO型、FER型、PLS-n型分子筛中的至少一种。
  7. 根据权利要求1-6中任一项所述的绝缘浆料，其中，
    所述二维无机材料的体积平均粒径Dv50为0.5μm～10μm，可选地为0.5μm～5μm；和/或，
    所述二维无机材料的径厚比≥50:1，可选地为50:1～100:1。
  8. 根据权利要求1-7中任一项所述的绝缘浆料，其中，所述有机溶剂包括N-甲基吡咯烷酮、磷酸三乙酯、二甲基亚砜、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺中的至少一种。
  9. 根据权利要求1-8中任一项所述的绝缘浆料，其中，所述绝缘浆料中乳化剂的质量百分含量小于等于1/1000000，可选地，所述绝缘浆料中乳化剂的质量百分含量为0％。
  10. 一种绝缘浆料的制备方法，包括以下步骤：
    S100，将有机溶剂和无机填料分散均匀，得到第一浆料；
    S200，在分散状态下向所得到的第一浆料中加入树脂粒子，分散均匀后得到绝缘浆料；
    其中，所述无机填料选自二维无机材料，所述树脂粒子选自悬浮聚合法制备的聚氟化烯烃树脂。
  11. 根据权利要求10所述的方法，其中，基于所述绝缘浆料的总质量计，所述树脂粒子的质量百分含量为1％～5％，所述无机填料的质量百分含量为5％～35％，所述有机溶剂的质量百分含量为60％～94％。
  12. 根据权利要求10或11所述的方法，其中，
    S100中，分散线速度为20m/s～100m/s，分散时间为15min～120min；和/或，
    S200中，分散线速度为20m/s～100m/s，分散时间为120min～480min。
  13. 根据权利要求10-12中任一项所述的方法，其中，所述方法还包括：
    S300，过滤所得到的绝缘浆料，可选地，使用100～200目滤网过滤所得到的绝缘浆料。
  14. 根据权利要求10-13中任一项所述的方法，其中，所述树脂粒子为一次颗粒，所述一次颗粒的体积平均粒径Dv50为20μm～150μm，可选地为50μm～100μm。
  15. 一种正极极片，包括：
    正极集流体；
    正极活性材料层，位于所述正极集流体至少部分表面；以及
    绝缘涂层，位于所述正极集流体表面并且沿所述正极集流体长度方向与所述正极活性材料层边缘相接，
    其中，所述绝缘涂层为根据权利要求1-9中任一项所述的绝缘浆料干燥后形成的层、或通过权利要求10-14中任一项所述的方法制备的绝缘浆料干燥后形成的层。
  16. 根据权利要求15所述的正极极片，其中，
    所述绝缘涂层的厚度为2μm～150μm；和/或，
    所述绝缘涂层的宽度为0.1mm～15mm。
  17. 一种二次电池，包括根据权利要求15或16所述的正极极片。
  18. 一种电池模块，包括根据权利要求17所述的二次电池。
  19. 一种电池包，包括根据权利要求17所述的二次电池、或根据权利要求18所述的电池模块。
  20. 一种用电装置，包括根据权利要求17所述的二次电池、根据权利要求18所述的电池模块、根据权利要求19所述的电池包中的至少一种。
PCT/CN2021/142341 2021-12-29 2021-12-29 绝缘浆料及其制备方法、正极极片、二次电池、电池模块、电池包及用电装置 WO2023123013A1 (zh)

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JP2023501548A JP2024508065A (ja) 2021-12-29 2021-12-29 絶縁スラリー及びその製造方法、正極極板、二次電池、電池モジュール、電池パック及び電力消費装置
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