WO2024092809A1 - 含氟聚合物、底涂浆料、二次电池、及用电装置 - Google Patents

含氟聚合物、底涂浆料、二次电池、及用电装置 Download PDF

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WO2024092809A1
WO2024092809A1 PCT/CN2022/130103 CN2022130103W WO2024092809A1 WO 2024092809 A1 WO2024092809 A1 WO 2024092809A1 CN 2022130103 W CN2022130103 W CN 2022130103W WO 2024092809 A1 WO2024092809 A1 WO 2024092809A1
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formula
monomer represented
fluorine
stage polymerization
slurry
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PCT/CN2022/130103
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English (en)
French (fr)
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冯伟
刘会会
欧阳楚英
孙成栋
左欢欢
张文帅
张帅
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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 CN202280092924.1A priority Critical patent/CN118765291A/zh
Priority to PCT/CN2022/130103 priority patent/WO2024092809A1/zh
Publication of WO2024092809A1 publication Critical patent/WO2024092809A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
    • C08F214/18—Monomers containing fluorine
    • C08F214/22—Vinylidene fluoride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a fluorine-containing polymer, a primer slurry, a secondary battery, and an electrical device.
  • a primer layer is coated between the current collector and the active material layer to provide electrical conduction between the active material layer and the current collector, thereby reducing the contact resistance between the active material layer and the current collector.
  • the primer layer is often prepared by coating the surface of the current collector with a primer slurry formulated with a binder, a conductive agent, and an additive.
  • the primer slurry in the prior art has a short process window, poor filterability, and is prone to precipitation and clogging of the pipeline, which seriously affects the production efficiency of the pole piece. Therefore, it is urgent to develop a polymer that can play the role of a binder while making the slurry have good dispersibility to improve the processing performance of the slurry.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a fluorine-containing polymer and a coating containing the fluorine-containing polymer to optimize the process window for coating preparation and improve the production efficiency of the primer layer.
  • the first aspect of the present application provides a fluorine-containing polymer, which comprises a structural unit derived from a monomer represented by formula I and a structural unit derived from a monomer represented by formula II, wherein the molar content of the structural unit derived from the monomer represented by formula I is 70% to 90%, based on the total molar number of the structural unit in the fluorine-containing polymer.
  • R1 , R2 , R3 are each independently selected from one or more of hydrogen, fluorine, chlorine atom, fluorine-substituted C1-3 alkyl
  • R4 , R5 , R6 are each independently selected from one or more of hydrogen, substituted or unsubstituted C1-5 alkyl
  • R7 is selected from substituted or unsubstituted C1-9 alkyl.
  • the fluorine-containing polymer provided in the present application reduces the viscosity of the slurry, improves the filterability, and improves the processability of the primer slurry, so that the primer slurry can meet the production requirements of the primer slurry without adding a dispersant, which is beneficial to optimizing the production process of the primer slurry and improving its production quality.
  • R 1 is fluorine
  • R 2 and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and trifluoromethyl
  • R 5 and R 6 are each independently selected from one or both of hydrogen and methyl.
  • the molar content of the structural unit derived from the monomer represented by formula II is 10% to 30%, based on the total molar number of the structural units in the fluorine-containing polymer.
  • the viscosity of the fluorine-containing polymer is appropriate, which can comprehensively improve the processability and adhesion of the slurry, and take into account the processing performance and use performance of the primer layer.
  • the weight average molecular weight of the fluorine-containing polymer is 400,000 to 500,000.
  • the fluorine-containing polymer with a weight average molecular weight of 400,000 to 500,000 has an appropriate viscosity, which can comprehensively improve the processability and adhesion of the slurry, and take into account the processing performance and use performance of the primer layer.
  • the monomer represented by formula I is selected from one or more of vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene.
  • the monomer represented by formula II is selected from one or more of methyl acrylate, ethyl acrylate, butyl acrylate, isopentyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
  • the second aspect of the present application provides a method for preparing a fluorine-containing polymer, comprising the following steps:
  • At least one monomer of formula I and at least one monomer of formula II are polymerized, wherein the molar content of the monomer of formula I is 70% to 90%, based on the total molar number of the monomer of formula I and the monomer of formula II.
  • R 1 , R 2 , and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and fluorine-substituted C 1-3 alkyl;
  • R 4 , R 5 , and R 6 are each independently selected from one or more of hydrogen, substituted or unsubstituted C 1-5 alkyl; and
  • R 7 is selected from substituted or unsubstituted C 1-9 alkyl.
  • the fluorinated polymer prepared by this method can improve the stability and bonding performance of the primer slurry, significantly broaden the process window of the primer slurry, and improve the performance of the primer slurry.
  • R 1 is fluorine
  • R 2 and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and trifluoromethyl
  • R 5 and R 6 are each independently selected from one or both of hydrogen and methyl.
  • the molar content of the monomer represented by formula II is 10% to 30%, based on the total molar number of the monomer represented by formula I and the monomer represented by formula II.
  • the viscosity of the fluorine-containing polymer is appropriate, which can comprehensively improve the processability and adhesion of the slurry, and take into account the processing performance and use performance of the primer layer.
  • the polymerization reaction includes a first stage polymerization and a second stage polymerization
  • First stage polymerization adding an initiator, a first emulsifier, at least one monomer represented by formula I and an aqueous medium into a reaction container to carry out first stage polymerization, and continuously feeding the monomer represented by formula I in the first stage polymerization;
  • Second stage polymerization After a period of reaction, an initiator, a second emulsifier, at least one monomer represented by formula II and an aqueous medium are added to the reaction container for second stage polymerization, and the monomer represented by formula I is continuously introduced in the second stage polymerization.
  • the method provided by the present application first continuously feeds the monomers shown in formula I to form fluorine-containing segments, thereby ensuring that the fluorine-containing polymer has high bonding performance; and then feeds the monomers shown in formula II to reduce the contact between the fluorine-containing segments and the external environment, thereby effectively reducing the viscosity of the slurry.
  • the fluorine-containing polymer prepared by the method can more effectively improve the stability and bonding performance of the primer slurry than the fluorine-containing polymer prepared by simultaneously polymerizing by feeding all the monomers into the reaction vessel, further broaden the process window and storage performance of the primer slurry, and help reduce the manufacturing cost of the primer.
  • the mass of the monomer of formula I introduced in the first stage polymerization is 90% to 95% of the total mass of the monomer of formula I supplied in the polymerization reaction
  • the mass of the monomer of formula I introduced in the second stage polymerization reaction is 5% to 10% of the total mass of the monomer of formula I supplied in the polymerization reaction.
  • the initiator provided in the first stage polymerization and the initiator provided in the second stage polymerization are both persulfate, and the mass percentage of the initiator provided in the first stage polymerization is 0.05% to 0.1%, based on the total mass of the monomer represented by formula I and the monomer represented by formula II; the mass percentage of the initiator provided in the second stage polymerization is 0.05% to 0.1%, based on the mass of the monomer represented by formula II.
  • the mass percentage of the first emulsifier is 0.2% to 0.7%, based on the total mass of the monomer represented by formula I and the monomer represented by formula II.
  • the mass percentage of the second emulsifier is 0.5% to 1.5%, based on the mass of the monomer represented by formula II.
  • the mass percentage of the aqueous medium provided in the first stage polymerization is 200% to 500%, and the mass percentage of the aqueous medium provided in the second stage polymerization is 100% to 200%, based on the total mass of the monomer represented by formula I and the monomer represented by formula II.
  • reaction pressure of the first stage polymerization is 5.5-7.5 MPa, and the reaction temperature is 75°C-85°C.
  • reaction pressure of the second stage polymerization is 4.5-6.5 MPa
  • reaction temperature is 86° C.-95° C.
  • a premixed liquid including the initiator, the second emulsifier, at least one monomer represented by formula II and an aqueous medium is added.
  • the first emulsifier is an alkali metal perfluorooctanoate.
  • the second emulsifier is one or both of polyoxyethylene-4-phenol ether ammonium sulfate and nonylphenol polyoxyethylene ether ammonium sulfate.
  • the third aspect of the present application provides an application of the fluorine-containing polymer of the first aspect in a secondary battery.
  • the secondary battery includes at least one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery.
  • the fourth aspect of the present application provides a primer slurry, comprising a binder, a conductive agent and a solvent, wherein the binder comprises the fluorine-containing polymer of the first aspect of the present application.
  • the primer slurry is easy to process and prepare and has good uniformity, which helps to improve battery production capacity.
  • the mass fraction of the binder is 0.5% to 5%, based on the mass of the conductive agent.
  • the solid content of the primer slurry is 15% to 30%, and the viscosity of the primer slurry is 100 mPa ⁇ s to 1000 mPa ⁇ s.
  • the viscosity of the primer slurry with a solid content of 15% to 30% is 100mPa ⁇ s to 1000mPa ⁇ s, which makes it unnecessary to add additional dispersants or thickeners to improve the processing performance of the primer slurry prepared by fluoropolymer, which helps to improve production efficiency and optimize the production process.
  • the primer slurry within this viscosity range has stability, fluidity and adhesion, which can not only improve the adhesion of the primer layer, but also achieve uniform coating, which is conducive to improving the batch stability of the primer layer.
  • the solvent is an organic solvent.
  • the solvent is selected from one or more of N-methylpyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-dipropylpropionamide, N,N-dibutylpropionamide, N,N-dimethylethylpropionamide and 3-butoxy-N-methylpropionamide.
  • a fifth aspect of the present application provides a method for preparing a primer layer, comprising the following steps:
  • the primer slurry is the primer slurry of the fourth aspect of the present application
  • the thickness of the base coating is 1 um to 3 um.
  • the primer slurry is gravure coated on the surface of the current collector. After drying, the primer layer with a thickness of 1um to 3um has a lower film resistance, which can ensure the electrical performance of the electrode and at the same time take into account the adhesion of the primer layer.
  • the sixth aspect of the present application provides a secondary battery, comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the negative electrode sheet comprises the primer layer of the fifth aspect of the present application.
  • the secondary battery includes at least one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery.
  • a seventh aspect of the present application provides a battery module, comprising the secondary battery of the sixth aspect of the present application.
  • An eighth aspect of the present application provides a battery pack, comprising the secondary battery of the sixth aspect of the present application or the battery module of the seventh aspect of the present application.
  • the ninth aspect of the present application provides an electrical device comprising at least one selected from the secondary battery of the sixth aspect of the present application, the battery module of the seventh aspect of the present application, or the battery pack of the eighth aspect of the present application.
  • FIG1 is a schematic diagram of a gravure coating process according to an embodiment of the present application.
  • FIG2 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG3 is an exploded view of the secondary battery of one embodiment of the present application shown in FIG2 ;
  • FIG4 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG5 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG6 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG5 ;
  • FIG. 7 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • range disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range.
  • the range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: 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).
  • the conductivity of the electrode is one of the most important research topics of secondary batteries.
  • a primer layer will be coated between the current collector and the active material layer to provide electrical conduction between the active material layer and the current collector, thereby reducing the contact resistance between the active material layer and the current collector and improving the performance of the battery.
  • binders and conductive agents are generally used to prepare the primer layer.
  • Traditional polyvinylidene fluoride binders will make the slurry have high viscosity and poor filterability, making it difficult to apply evenly. Therefore, a dispersant needs to be added during the slurry preparation process to improve the processing performance of the slurry.
  • the present application has developed a polymer that can play the role of a binder and a dispersant in the primer slurry, improve the filterability and stability of the primer slurry, and help improve the production efficiency and production quality of the primer.
  • a fluorine-containing polymer which comprises a structural unit derived from a monomer represented by formula I and a structural unit derived from a monomer represented by formula II, wherein the molar content of the structural unit derived from the monomer represented by formula I is 70% to 90%, based on the total molar number of the structural units of the fluorine-containing polymer.
  • R 1 , R 2 , and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and fluorine-substituted C 1-3 alkyl;
  • R 4 , R 5 , and R 6 are each independently selected from one or more of hydrogen, substituted or unsubstituted C 1-5 alkyl; and
  • R 7 is selected from substituted or unsubstituted C 1-9 alkyl.
  • fluorine-containing polymer refers to a polymer containing fluorine in its structural units.
  • polymer includes, on the one hand, a collection of macromolecules that are chemically uniform but differ in degree of polymerization, molar mass and chain length, prepared by polymerization.
  • the term also includes, on the other hand, derivatives of such a collection of macromolecules formed by polymerization, i.e. products that can be obtained by reaction of functional groups in the above-mentioned macromolecules, such as addition or substitution, and can be chemically uniform or chemically inhomogeneous.
  • C 1-5 alkyl refers to a straight or branched hydrocarbon chain group consisting solely of carbon and hydrogen atoms, with no unsaturation in the group, having from one to five carbon atoms, and attached to the rest of the molecule by a single bond.
  • C 1-3 alkyl and the term “C 1-9 alkyl” should be interpreted accordingly.
  • Examples of C 1-5 alkyl include, but are not limited to, methyl, ethyl, n-propyl, 1 -methylethyl (isopropyl), butyl, pentyl.
  • fluorine-substituted C 1-3 alkyl is -CF 3 , -CH 3 CH 2 F, -CH 2 FCH 2 F.
  • C 1-9 alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, and n-nonyl.
  • substituted means that at least one hydrogen atom of the compound or chemical moiety is replaced by another chemical moiety with a substituent, wherein the substituent is independently selected from: hydroxyl, thiol, amino, cyano, nitro, aldehyde, halogen atom, alkenyl, alkynyl, aryl, heteroaryl, C 1-6 alkyl, C 1-6 alkoxy.
  • process window refers to the process range that can ensure product quality, including but not limited to temperature range, pressure range, storage time length, etc. It can be understood that the wider the process window, the lower the requirement for process accuracy.
  • R 1 is fluorine
  • R 2 and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine atoms, and trifluoromethyl groups
  • R 5 and R 6 are each independently selected from one or both of hydrogen and methyl groups.
  • the monomer represented by formula I is selected from one or more of vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene.
  • the monomer represented by formula II is selected from one or more of methyl acrylate, ethyl acrylate, butyl acrylate, isopentyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
  • the polymer comprises one or more structural units derived from the monomers shown in formula I. In some embodiments, the polymer comprises one or more structural units derived from the monomers shown in formula II. In some embodiments, the polymer includes but is not limited to vinylidene fluoride-methyl acrylate copolymer, vinylidene fluoride-ethyl acrylate copolymer, vinylidene fluoride-butyl acrylate copolymer, vinylidene fluoride-isoamyl acrylate copolymer, vinylidene fluoride-isooctyl acrylate copolymer, vinylidene fluoride-methyl methacrylate copolymer, vinylidene fluoride-ethyl methacrylate copolymer, vinylidene fluoride-hydroxyethyl acrylate copolymer, vinylidene fluoride-hydroxypropyl acrylate copolymer, vinylidene fluoride-tetra
  • the molar content of the structural unit derived from the monomer represented by Formula I can be selected from 70%, 75%, 80%, 85% or 90%, based on the total moles of the structural unit in the fluorine-containing polymer.
  • the fluorine element in the structural unit derived from the monomer shown in formula I can form hydrogen bonds with the hydroxyl and/or carboxyl groups on the surface of the current collector, so that the primer layer has good adhesion and is not easy to fall off during the manufacturing and use process, causing safety accidents; the structural unit derived from the monomer shown in formula II can effectively reduce the fluorine content of the fluorine-containing polymer, so that the mass content of the structural unit derived from the monomer shown in formula I is 70% to 90%, which helps to adjust the viscosity of the slurry, improve the phenomenon of excessive viscosity of the primer slurry caused by the fluorine element, and improve the processability of the slurry.
  • the fluorine-containing polymer provided in the present application reduces the viscosity of the slurry, improves the filterability, and improves the processability of the primer slurry, so that the primer slurry can meet the production requirements of the primer slurry without adding a dispersant, which is beneficial to optimizing the production process of the primer slurry and improving its production quality.
  • the molar content of the structural unit derived from the monomer shown in formula II is 10% to 30%, based on the total molar number of the structural unit in the fluoropolymer. In some embodiments, the molar content of the structural unit derived from the monomer shown in formula II can be selected from any one of 12%, 15%, 18%, 20%, 22%, 25%, and 30%, based on the total molar number of the structural unit in the fluoropolymer.
  • the viscosity of the fluorine-containing polymer is appropriate, so that the electrode has good adhesion.
  • the appropriate viscosity makes the slurry have good fluidity and filterability, which can comprehensively improve the processability and adhesion of the slurry, taking into account the processing performance and use performance of the base coating.
  • the weight average molecular weight of the fluorine-containing polymer is 400,000 to 500,000. In some embodiments, the weight average molecular weight of the fluorine-containing polymer can be any one of 430,000, 450,000, and 480,000.
  • weight average molecular weight refers to the sum of the products of the weight fractions of molecules with different molecular weights in a polymer and their corresponding molecular weights.
  • the weight average molecular weight of the polymer can be tested by methods known in the art, such as gel chromatography, such as Waters 2695 Isocratic HPLC gel chromatograph (differential refractive index detector 2141).
  • the test method is to use a polystyrene solution sample with a mass fraction of 3.0% as a reference and select a matching chromatographic column (oily: Styragel HT5DMF7.8*300mm+Styragel HT4).
  • NMP N-methylpyrrolidone
  • Fluorine-containing polymers with a weight-average molecular weight of 400,000 to 500,000 have an appropriate viscosity, which enables the electrode to have good adhesion.
  • the appropriate viscosity is conducive to subsequent coating work, and can comprehensively improve the processability and adhesion of the slurry, taking into account the processing performance and use performance of the primer layer.
  • a method for preparing a fluorine-containing polymer comprising the following steps:
  • At least one monomer represented by formula I and at least one monomer represented by formula II are polymerized, wherein the molar content of the monomer represented by formula I is 70% to 90%, based on the total molar number of the monomer represented by formula I and the monomer represented by formula II,
  • R 1 , R 2 , and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and fluorine-substituted C 1-3 alkyl;
  • R 4 , R 5 , and R 6 are each independently selected from one or more of hydrogen, substituted or unsubstituted C 1-5 alkyl; and
  • R 7 is selected from substituted or unsubstituted C 1-9 alkyl.
  • polymerizable conditions refers to those conditions including temperature, pressure, reactant concentrations, optional solvents/diluents, reactant mixing/addition parameters selected by one skilled in the art, and other conditions that facilitate the reaction of one or more monomers within at least one polymerization reactor.
  • the fluorinated polymer prepared by this method can improve the stability and bonding performance of the primer slurry, significantly broaden the process window of the primer slurry, and improve the performance of the primer slurry.
  • R 1 is fluorine
  • R 2 and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and trifluoromethyl
  • R 5 and R 6 are each independently selected from one or both of hydrogen and methyl.
  • the molar content of the monomer shown in formula II is 10% to 30%, based on the total molar number of the monomer shown in formula I and the monomer shown in formula II. In some embodiments, the molar content of the structural unit derived from the monomer shown in formula II can be selected as any one of 12%, 15%, 18%, 20%, 22%, 25%, and 30%, based on the total molar number of the monomer shown in formula I and the monomer shown in formula II.
  • the viscosity of the fluorine-containing polymer is appropriate, which can comprehensively improve the processability and adhesion of the slurry, and take into account the processing performance and use performance of the primer layer.
  • the polymerization reaction includes a first stage polymerization and a second stage polymerization
  • First stage polymerization adding an initiator, a first emulsifier, at least one monomer represented by formula I and an aqueous medium into a reaction container to carry out first stage polymerization, and continuously feeding the monomer represented by formula I in the first stage polymerization;
  • Second stage polymerization After a period of reaction, an initiator, a second emulsifier, at least one monomer represented by formula II and an aqueous medium are added to the reaction container for second stage polymerization, and the monomer represented by formula I is continuously introduced in the second stage polymerization.
  • continuous feed refers to the slow, small, incremental addition of monomers.
  • the method provided by the present application first continuously feeds the monomer shown in formula I to form a fluorine-containing segment, thereby ensuring that the fluorine-containing polymer has high bonding performance; and then feeds the monomer shown in formula II to reduce the contact between the fluorine-containing segment and the external environment, thereby effectively reducing the viscosity of the slurry.
  • the fluorine-containing polymer prepared by this method can more effectively improve the stability and bonding performance of the primer slurry than the fluorine-containing polymer prepared by simultaneously polymerizing by feeding all the monomers into the reaction vessel, further broadening the process window and storage performance of the primer slurry, and helping to reduce the manufacturing cost of the primer layer.
  • the initiator provided in the first stage polymerization and the initiator provided in the second stage polymerization are both persulfate, and the mass percentage of the initiator provided in the first stage polymerization is 0.05% to 0.1%, based on the total mass of the monomer represented by formula I and the monomer represented by formula II; the mass percentage of the initiator provided in the second stage polymerization is 0.05% to 0.1%, based on the mass of the monomer represented by formula II.
  • the initiator persulfate may be potassium persulfate, which effectively decomposes at above 60° C. to generate free radical ions or ionic free radicals, and is suitable as an initiator for emulsion polymerization.
  • the mass percentage of the initiator provided in the first stage polymerization is 0.05%, 0.07%, 0.09% or 0.1%, based on the total mass of the monomers represented by formula I and the monomers represented by formula II.
  • the mass percentage of the initiator provided in the second stage polymerization is 0.05%, 0.07%, 0.09% or 0.1%, based on the mass of the monomer represented by Formula II.
  • the mass percentage of the first emulsifier is 0.2% to 0.7%, based on the total mass of the monomers shown in Formula I and the monomers shown in Formula II. In some embodiments, the mass percentage of the first emulsifier is 0.2%, 0.5% or 0.7%, based on the total mass of the monomers shown in Formula I and the monomers shown in Formula II.
  • the first emulsifier is an alkali metal perfluorooctanoate.
  • the mass percentage of the second emulsifier is 0.5% to 1.5%, based on the mass of the monomer of formula II. In some embodiments, the mass percentage of the second emulsifier is 0.5%, 0.75%, 1.0%, 1.25% or 1.5%, based on the mass of the monomer of formula II.
  • the second emulsifier is one or both of polyoxyethylene-4-phenol ether ammonium sulfate and nonylphenol polyoxyethylene ether ammonium sulfate.
  • the mass percentage of the aqueous medium provided in the first stage of polymerization is 200% to 500%
  • the mass percentage of the aqueous medium provided in the second stage of polymerization is 100% to 200%, based on the total mass of the monomers shown in Formula I and the monomers shown in Formula II.
  • the mass percentage of the aqueous medium provided in the first stage of polymerization is 200%, 300%, 400% or 500%
  • the mass percentage of the aqueous medium provided in the second stage of polymerization is 100%, 150% or 200%, based on the total mass of the monomers shown in Formula I and the monomers shown in Formula II.
  • the aqueous medium is an aqueous solvent, which can be deionized water or a mixture of deionized water and other hydrophilic solvents, such as alcohol or ethyl acetate.
  • the reaction pressure of the first stage polymerization is 5.5-7.5 MPa, and the reaction temperature is 75° C.-85° C. In some embodiments, the reaction pressure of the first stage polymerization is 5.5 MPa, 6.5 MPa or 7.5 MPa, and the reaction temperature is 75° C., 80° C. or 85° C.
  • the reaction pressure of the second stage polymerization is 4.5-6.5 MPa, and the reaction temperature is 86° C.-95° C. In some embodiments, the reaction pressure of the second stage polymerization is 4.5 MPa, 5.5 MPa or 6.5 MPa, and the reaction temperature is 86° C., 90° C. or 95° C.
  • the mass of the monomer of formula I introduced in the first stage of polymerization is 90% to 95% of the total mass of the monomer of formula I supplied in the polymerization reaction, and the mass of the monomer of formula I introduced in the second stage of polymerization is 5% to 10% of the total mass of the monomer of formula I supplied in the polymerization reaction.
  • the mass of the monomer of formula I introduced in the first stage of polymerization is 90%, 92% or 95% of the total mass of the monomer of formula I supplied in the polymerization reaction, and the mass of the monomer of formula I introduced in the second stage of polymerization is 5%, 7% or 10% of the total mass of the monomer of formula I supplied in the polymerization reaction.
  • providing an initiator, a second emulsifier, at least one monomer represented by Formula II, and an aqueous medium into a reaction container for second stage polymerization comprises:
  • a premixed liquid including the initiator, the second emulsifier, at least one monomer represented by formula II and an aqueous medium is added.
  • a fluorinated polymer in any embodiment is provided for use in a secondary battery, and optionally, the secondary battery includes at least one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery.
  • the fluorinated polymer is used as a binder in a secondary battery.
  • the fluorinated polymer is used as a binder for a primer layer in a secondary battery.
  • a primer slurry comprising a binder, a conductive agent and a solvent, wherein the binder comprises a fluorine-containing polymer in any embodiment.
  • binder refers to a chemical compound, polymer or mixture that forms a colloidal solution or colloidal dispersion in a dispersion medium.
  • conductive agent refers to a substance that collects microcurrents, including but not limited to at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the solvent is an organic solvent.
  • Organic solvent refers to an organic compound containing carbon atoms as a solvent. Organic solvents can dissolve some substances that are insoluble in water. Using organic solvents as solvents for the primer makes the primer slurry suitable for preparing the primer of the negative electrode sheet. The primer is not easily dissolved during the preparation of the negative electrode film layer and has high stability.
  • the solvent is selected from one or more of N-methylpyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-dipropylpropionamide, N,N-dibutylpropionamide, N,N-dimethylethylpropionamide and 3-butoxy-N-methylpropionamide.
  • the primer slurry is easy to process and prepare and has good uniformity, which helps to improve battery production capacity.
  • the mass fraction of the binder is 0.5% to 5%, based on the mass of the conductive agent. In some embodiments, the mass content of the binder can be any one of 0.5%, 1.0%, 2.0%, 4.0%, and 5.0%, based on the mass of the conductive agent.
  • the base coating and the current collector have sufficient bonding force to avoid the risk of the base coating falling off during the use of the battery cell; at the same time, when the mass content of the binder is within an appropriate range, the base coating slurry has an appropriate viscosity, and the slurry has good fluidity and filterability, which is beneficial to subsequent coating work.
  • the solid content of the primer slurry is 15% to 30%, and the viscosity of the primer slurry is 100 mPa ⁇ s to 1000 mPa ⁇ s. In some embodiments, when the solid content of the primer slurry is 15% to 30%, the viscosity of the primer slurry is 100 mPa ⁇ s, 200 mPa ⁇ s, 300 mPa ⁇ s, 400 mPa ⁇ s, 500 mPa ⁇ s, 600 mPa ⁇ s, 700 mPa ⁇ s, 800 mPa ⁇ s, 900 mPa ⁇ s or 1000 mPa ⁇ s.
  • the viscosity of the primer slurry is within an appropriate range, which is beneficial to subsequent coating and drying work on the one hand; on the other hand, the appropriate viscosity can improve the stability of the slurry, making the slurry have good fluidity and filterability.
  • the viscosity of the fluorine-containing polymer primer slurry can be tested by a method known in the art, such as using a rotary viscosity tester.
  • the viscosity of the primer slurry with a solid content of 15% to 30% is 100mPa ⁇ s to 1000mPa ⁇ s, which makes it unnecessary to add additional dispersants or thickeners to improve the processing performance of the primer slurry prepared by fluoropolymer, which helps to improve production efficiency and optimize the production process.
  • the primer slurry within this viscosity range has stability, fluidity and adhesion, which can not only improve the adhesion of the primer layer, but also achieve uniform coating, which is conducive to improving the batch stability of the primer layer.
  • a method for preparing a primer layer comprising the following steps:
  • the primer slurry is gravure coated on the surface of the current collector, and the primer slurry is the primer slurry in any embodiment; the primer slurry is dried to obtain a primer layer.
  • the gravure coating process is shown in FIG1 , where a gravure roller 62 in a gravure coating device 6 is partially immersed in the slurry in a slurry tank 65, the gravure roller 62 rotates to drive the slurry to move, a scraper 64 scrapes off the slurry on the smooth part of the gravure roller 62, and the slurry remaining in the pits on the surface of the gravure roller 62 is transferred to the surface of the current collector 63 under the pressure of the pressure roller 61, wherein the rotation direction of the gravure roller 62 is opposite to the movement direction of the pressure roller 61.
  • the depth of the pits on the surface of the gravure roller 62 can be adjusted according to the required thickness of the primer layer, and the depth of the pits can be selected to be 10-100um.
  • the surface of the primer layer prepared by gravure coating is rough, and the bonding performance between the primer layer and the film layer or the current collector can be improved by mechanical riveting, so that the pole piece has better bonding force.
  • the thickness of the primer layer is 1 um to 3 um.
  • the primer slurry is gravure coated on the surface of the current collector. After drying, the primer layer with a thickness of 1um to 3um has excellent adhesion and low film resistance, which can ensure the mechanical and electrochemical properties of the electrode.
  • a secondary battery comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the negative electrode sheet comprises a primer layer as described in any embodiment.
  • the secondary battery comprises at least one of a lithium ion battery, a sodium ion battery, a magnesium ion battery and a potassium ion battery.
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the separator is set between the positive electrode and the negative electrode, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material for a battery known in the art.
  • the positive electrode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to , lithium cobalt oxide (such as LiCoO2 ), lithium nickel oxide (such as LiNiO2 ), lithium manganese oxide (such as LiMnO2 , LiMn2O4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333 ), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523 ) , LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211 ) , LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector, a primer layer disposed on at least one surface of the negative electrode current collector, and a negative electrode film layer disposed on the primer layer, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may adopt the negative electrode active material for the battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet can be prepared by the following method: the above components for preparing the primer layer, such as fluorine-containing polymers and conductive agents, are dispersed in N-methyl-2-pyrrolidone to form a primer slurry; the primer slurry is gravure coated on the surface of the copper foil current collector to obtain a current collector with a primer layer.
  • the above components for preparing the negative electrode film layer such as negative electrode active materials, conductive agents, binders and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the current collector with the primer layer, and after drying, cold pressing and other processes, a negative electrode sheet can be obtained.
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.
  • the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may further include additives.
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the secondary battery further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the secondary battery may include an outer package that can be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG2 is a secondary battery 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into a battery module.
  • the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG4 is 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. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a housing space, and the plurality of secondary batteries 5 are housed in the housing space.
  • the battery modules described above may also be assembled into a battery pack.
  • the battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
  • FIG5 and FIG6 are battery packs 1 as an example.
  • 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, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • FIG7 is an example of an electric 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 may be used.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • the reactor was evacuated and filled with nitrogen, and the operation was repeated until the oxygen concentration in the reactor was less than 100 ppm;
  • Vinylidene fluoride monomer was introduced into the reactor, and the pressure in the reactor was 7.5 MPa. The reaction started when the temperature in the reactor was raised to 85°C. Vinylidene fluoride monomer was continuously introduced during the reaction to maintain the reaction pressure in the reactor unchanged.
  • the reaction product is cooled to room temperature, and then condensed, washed, separated, dried and crushed to obtain a vinylidene fluoride-butyl acrylate copolymer binder.
  • the slurry was filtered through a 200-mesh filter to obtain a primer slurry.
  • the primer slurry is coated using the gravure coating device shown in Figure 1.
  • the primer slurry is first injected into the slurry tank, and the primer slurry is carried by the gravure roller. After the primer slurry on the smooth part is scraped off by a scraper, the remaining primer slurry remains only in the pits on the surface of the gravure roller. The depth of the pits is 50um. Under the pressure of the pressure roller, the primer slurry in the pits can be transferred to the surface of the copper foil current collector substrate, and dried to obtain a primer layer with a thickness of 2um.
  • the graphite material, the conductive agent carbon black, the styrene-butadiene binder, the sodium carboxymethyl cellulose, and the N-methylpyrrolidone (NMP) are stirred and mixed uniformly in a weight ratio of 97.15:0.04:1.95:0.5:0.36 to obtain a negative electrode slurry, and the solid content of the slurry is 64%;
  • the negative electrode slurry is evenly coated on the base coating, and then dried, cold pressed and cut to obtain the negative electrode sheet.
  • Example 4 the reaction conditions in the synthesis of the fluorinated polymer were adjusted so that the fluorinated polymer had different weight average molecular weights, and the other parameters were the same as in Example 1.
  • the specific parameters are shown in Tables 1 and 2.
  • the preparation method of the fluorinated polymer with a weight average molecular weight of 300,000 in Example 4 is basically the same as that in Example 1, except that the amount of the 5% concentration potassium persulfate solution added was adjusted to 99.00 g.
  • the preparation method of the fluorine-containing polymer with a weight average molecular weight of 400,000 in Example 5 is basically the same as the steps in Example 1, except that the amount of 5% potassium persulfate solution added is adjusted to 99.45 g.
  • the preparation method of the fluorine-containing polymer with a weight average molecular weight of 500,000 in Example 6 is basically the same as the steps in Example 1, except that the reaction temperature is adjusted to 80° C. and the amount of 5% potassium persulfate solution added is adjusted to 89.45 g.
  • the preparation method of the fluorine-containing polymer with a weight average molecular weight of 600,000 in Example 7 is basically the same as the steps in Example 1, except that the reaction temperature is adjusted to 80° C. and the amount of 5% potassium persulfate solution added is adjusted to 81.00 g.
  • Example 8 the mass fraction of the binder in the primer slurry was adjusted, and other parameters were kept consistent with those in Example 1.
  • the specific parameters are shown in Tables 1 and 2.
  • Example 12 the solid content of the primer slurry was adjusted, and other parameters were kept consistent with those in Example 1. The specific parameters are shown in Tables 1 and 2.
  • Example 16 the ethyl acrylate monomer is replaced by isooctyl acrylate monomer, and other parameters are the same as in Example 1. For specific parameters, see Table 1 and Table 2.
  • Example 17 the base coating layer was prepared by a blade coating method. Other methods were the same as in Example 1. For specific parameters, see Tables 1 and 2.
  • Example 18 the preparation method is consistent with that of Example 1, except that the binder in the primer layer is a vinylidene fluoride-butyl acrylate copolymer prepared by a conventional method, and the synthesis method thereof is:
  • the reactor was evacuated and filled with nitrogen, and the operation was repeated until the oxygen concentration in the reactor was less than 100 ppm;
  • Vinylidene fluoride monomer and 23.3 mol of butyl acrylate were introduced into the reactor until the pressure inside the reactor reached 7.5 MPa;
  • the temperature in the kettle was raised to 85°C to start the reaction.
  • vinylidene fluoride monomer was continuously introduced to maintain the reaction pressure in the kettle constant.
  • the molar number of the vinylidene fluoride monomer introduced was 70 mol.
  • the mixture is cooled to room temperature, condensed, washed, separated, dried and crushed to obtain a fluorine-containing polymer, namely, a vinylidene fluoride-butyl acrylate copolymer.
  • Comparative Example 1 the preparation method is consistent with that of Example 1, except that in Comparative Example 1, vinylidene fluoride polymer is used as the binder of the primer slurry, which is HSV900 model of Arkema, France.
  • Comparative Example 2 is basically the same as Comparative Example 1, except that the preparation method of the primer layer is adjusted.
  • the specific preparation method is:
  • the primer slurry was coated on the surface of the copper foil current collector substrate by using a scraper, and dried to obtain a primer layer with a thickness of 2 ⁇ m.
  • a Waters 2695 Isocratic HPLC gel chromatograph (differential refractive index detector 2141) was used.
  • a polystyrene solution sample with a mass fraction of 3.0% was used as a reference, and a matching chromatographic column (oily: Styragel HT5DMF7.8 ⁇ 300mm+Styragel HT4) was selected.
  • a 3.0% fluoropolymer solution was prepared with purified N-methylpyrrolidone (NMP) solvent, and the prepared solution was allowed to stand for one day for use. During the test, tetrahydrofuran was first drawn with a syringe and rinsed, and repeated several times.
  • NMP N-methylpyrrolidone
  • a rotating viscometer to measure the viscosity of the primer slurry.
  • Select a suitable rotor fix the viscometer rotor, place the primer slurry under the viscometer rotor, and the slurry just submerges the scale line of the rotor.
  • the solid content is (M2-M0)/(M1-M0);
  • the solid content of the upper and lower primer slurries after standing for 24 hours was measured in the same way, and the solid content of the lower primer slurry minus the solid content of the upper primer slurry was taken as the difference in solid content of the primer slurry after standing for 24 hours.
  • the adhesion test process of the embodiment and comparative example of the present application is as follows: Use a blade to cut a sample with a width of 30mm and a length of 150mm, and stick the special double-sided tape on the steel plate, the tape width is 20mm and the length is 100mm. Stick the negative electrode film layer of the electrode sample cut earlier on the double-sided tape, and then roll it three times in the same direction with a 2kg roller. Fix a paper tape with a width equal to the electrode and a length of 250mm on the electrode collector and fix it with wrinkled glue.
  • the indicator light is on, adjust the limit block to the appropriate position, and fix the end of the steel plate without the electrode with the lower clamp. Fold the paper tape upwards and fix it with the upper clamp, and use the "up” and “down” buttons on the manual controller attached to the tensile machine to adjust the position of the upper clamp. Then test and read the value, the tensile speed is 50mm/min. The force when the electrode is under force balance divided by the width of the tape is taken as the bonding force per unit length of the negative electrode, which characterizes the bonding strength between the film layer on the current collector and the current collector.
  • the copper foil should extend about 5cm beyond the table. Press down the copper foil on the table to prevent it from moving.
  • the micrometer was purchased from Mitutoyo Co., Ltd. of Japan.
  • the copper foil is gravure coated on one side and dried, it is placed on a flat table.
  • the copper foil is about 5 cm wide beyond the table.
  • the copper foil on the table is pressed to prevent it from moving.
  • Thickness of the primer layer (L2 - L1).
  • the binders in Examples 1-18 are all fluoropolymers, including structural units derived from vinylidene fluoride and structural units derived from acrylate, and the molar content of the structural units derived from vinylidene fluoride in the polymer is 70% to 90%, based on the total molar number of the structural units in the fluoropolymer.
  • the above-mentioned fluoropolymers as binders have achieved good results.
  • the fluoropolymers provided in this application reduce the viscosity of the slurry and improve the filterability, which is suitable for preparing the primer layer.
  • the mass fraction of the fluorine-containing polymer is 0.5% to 5%. Based on the mass of the conductive agent, the viscosity of the fluorine-containing polymer is appropriate and suitable for preparing a uniform primer layer. It can comprehensively improve the processability and adhesion of the slurry, taking into account the processing performance and use performance of the primer layer.
  • the viscosity of the primer slurry with a mass fraction of 0.5% to 5% of the fluorinated polymer and a solid content of 15% to 30% is 100 mPa ⁇ s-1000 mPa ⁇ s, which means that the primer slurry prepared from the fluorinated polymer does not need to add additional dispersants or thickeners to improve processing performance, which helps to reduce the variability between slurry batches, improve production efficiency, and optimize the production process.

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Abstract

本申请提供了一种含氟聚合物、底涂浆料、二次电池和用电装置。含氟聚合物包含衍生自式I所示单体的结构单元、衍生自式II所示单体的结构单元，衍生自式I所示单体的结构单元的摩尔含量为70％～90％，基于含氟聚合物中结构单元的总质量计，其中，R1、R2、R3各自独立地选自氢、氟、氯、氟取代的C1-3烷基中的一种或多种，R4、R5、R6各自独立地选自氢、取代或未取代的C1-5烷基中的一种或多种，R7选自取代或未取代的C1-9烷基。

Description

含氟聚合物、底涂浆料、二次电池、及用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种含氟聚合物、底涂浆料、二次电池、及用电装置。
背景技术
二次电池极片在制备过程中，会在集流体与活性材料层之间涂覆底涂层，提供活性材料层和集流体之间的电导通，进而降低活性材料层与集流体之间的接触电阻。底涂层常通过以粘结剂、导电剂、助剂为配方的底涂浆料在集流体表面的涂覆制备，然而现有技术中的底涂浆料工艺窗口短、过滤性差、易发生沉淀堵塞管道，严重影响极片的生产效率。因此，亟需开发出一种聚合物能够在发挥粘结剂作用的同时使得浆料具有良好的分散性，以改善浆料的加工性能。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种含氟聚合物及包含该含氟聚合物的涂层，以优化涂层制备的工艺窗口、提高底涂层的生产效率。
本申请的第一方面提供了一种含氟聚合物，其包含衍生自式I所示单体的结构单元和衍生自式II所示单体的结构单元，所述衍生自式I所示单体的结构单元的摩尔含量为70％～90％，基于所述含氟聚合物中结构单元的总摩尔数计，
Figure PCTCN2022130103-appb-000001
其中，R 1、R 2、R 3各自独立地选自氢、氟、氯原子、氟取代的C 1-3烷基中的一种或多种，R 4、R 5、R 6各自独立地选自氢、取代或未取代的 C 1-5烷基中的一种或多种，R 7选自取代或未取代的C 1-9烷基。
本申请提供的含氟聚合物相比于现有技术中常用的聚二氟乙烯粘结剂使得浆料的粘度有所下降，过滤性有所提高，改善了底涂浆料的可加工性，使得底涂浆料在无需添加分散剂的情况下就能够满足底涂浆料的生产需求，有利于优化底涂浆料的生产工艺和提高其生产品质。
在任意实施方式中，所述R 1为氟，R 2、R 3各自独立地选自氢、氟、氯、三氟甲基中的一种或多种，R 5、R 6各自独立地选自氢、甲基中的一种或两种。
在任意实施方式中，所述衍生自式II所示单体的结构单元的摩尔含量为10％～30％，基于所述含氟聚合物中结构单元的总摩尔数计。
基于含氟聚合物的结构单元的总摩尔数计，衍生自式II所示单体的结构单元的摩尔含量为10％～30％时，含氟聚合物的粘度适宜，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
在任意实施方式中，所述含氟聚合物的重均分子量为40万～50万。
重均分子量在40万～50万的含氟聚合物粘度适宜，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
在任意实施方式中，所述式I所示单体选自氟乙烯、偏二氟乙烯、四氟乙烯、三氟氯乙烯、六氟丙烯中的一种或多种。
在任意实施方式中，所述式II所示单体选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯、丙烯酸异戊酯、丙烯酸异辛酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、丙烯酸羟乙酯、丙烯酸羟丙酯中的一种或多种。
本申请的第二方面提供一种含氟聚合物的制备方法，包括以下步骤：
在可聚合条件下，将至少一种式I所示单体和至少一种式II所示单体进行聚合反应，所述式I所示单体的摩尔含量为70％～90％，基 于式I所示单体和式II所示单体的总摩尔数计，
Figure PCTCN2022130103-appb-000002
其中，R 1、R 2、R 3各自独立地选自氢、氟、氯、氟取代的C 1-3烷基中的一种或多种，R 4、R 5、R 6各自独立地选自氢、取代或未取代的C 1-5烷基中的一种或多种，R 7选自取代或未取代的C 1-9烷基。
该方法制备出的含氟聚合物相比于传统粘结剂能够提高底涂浆料的稳定性能和粘结性能，显著拓宽了底涂浆料的工艺窗口，改善了底涂浆料的使用性能。
在任意实施方式中，所述R 1为氟，R 2、R 3各自独立地选自氢、氟、氯、三氟甲基中的一种或多种，R 5、R 6各自独立地选自氢、甲基中的一种或两种。
在任意实施方式中，所述式II所示单体的摩尔含量为10％～30％，基于式I所示单体和式II所示单体的总摩尔数计。
基于含氟聚合物的结构单元的总摩尔含量计，衍生自式II所示单体的结构单元的摩尔含量为10％～30％时，含氟聚合物的粘度适宜，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
在任意实施方式中，所述聚合反应包括第一段聚合和第二段聚合，
第一段聚合：向反应容器内加入引发剂、第一乳化剂、至少一种式I所示单体以及水性介质进行第一段聚合，在所述第一段聚合中连续送入式I所示单体；
第二段聚合：反应一段时间后，向反应容器内加入引发剂、第二乳化剂、至少一种式II所示单体以及水性介质进行第二段聚合，在所述第二段聚合中连续送入式I所示单体。
本申请提供的方法通过首先连续送入式I所示单体形成含氟链段，保证含氟聚合物具有较高的粘结性能；再通入式II所示单体以减少含氟链段与外界环境的接触，能够有效降低浆料的粘度。该方法制备出的含氟聚合物相比于通过将单体全部通入反应容器同时聚合制 备的含氟聚合物更能有效提高底涂浆料的稳定性和粘结性能，进一步拓宽底涂浆料的工艺窗口和储存性能，有助于降低底涂层的制造成本。
在任意实施方式中，所述第一段聚合中通入的式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的90％～95％，所述第二段聚合反应中通入的式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的5％～10％。
在任意实施方式中，所述第一段聚合中提供的引发剂和所述第二段聚合中提供的引发剂均为过硫酸盐，所述第一段聚合中提供的引发剂的质量百分比为0.05％～0.1％，基于所述式I所示单体和式II所示单体的总质量计；所述第二段聚合中提供的引发剂的质量百分比为0.05％～0.1％，基于所述式II所示单体的质量计。
在任意实施方式中，所述第一乳化剂的质量百分比为0.2％～0.7％，基于所述式I所示单体和式II所示单体的总质量计。
在任意实施方式中，所述第二乳化剂的质量百分比为0.5％～1.5％，基于所述式II所示单体的质量计。
在任意实施方式中，所述第一段聚合中提供的水性介质的质量百分比为200％～500％，所述第二段聚合中提供的水性介质的质量百分比为100％～200％，基于所述式I所示单体和式II所示单体的总质量计。
在任意实施方式中，所述第一段聚合的反应压力为5.5～7.5MPa，反应温度为75℃～85℃。
在任意实施方式中，所述第二段聚合的反应压力为4.5～6.5MPa，反应温度为86℃～95℃。
在任意实施方式中，所述反应一段时间后，向反应容器内提供引发剂、第二乳化剂、至少一种式II所示单体以及水性介质进行第二段聚合包括：
向反应容器内，加入引发剂后，再加入包含引发剂、第二乳化剂、至少一种式II所示单体以及水性介质在内的预混液。
在任意实施方式中，所述第一乳化剂为全氟辛酸碱金属盐。
在任意实施方式中，所述第二乳化剂为聚氧乙烯-4-酚基醚硫酸铵盐、壬基酚聚氧乙烯醚硫酸铵盐中的一种或两种。
本申请的第三方面，提供第一方面的含氟聚合物在二次电池中的应用，可选地，所述二次电池包括锂离子电池、钠离子电池、镁离子电池、钾离子电池中的至少一种。
本申请的第四方面提供一种底涂浆料，包括粘结剂、导电剂和溶剂，所述粘结剂包含本申请第一方面的含氟聚合物。
该底涂浆料易于加工制备且均匀性好，有助于提高电池产能。
在任意实施方式中，所述粘结剂的质量分数为0.5％～5％，基于所述导电剂的质量计。
在任意实施方式中，所述底涂浆料的固含量为15％～30％，所述底涂浆料的粘度为100mPa·s～1000mPa·s。
固含量为15％～30％的底涂浆料的粘度为100mPa·s～1000mPa·s，这使得含氟聚合物制备的底涂浆料无需添加额外的分散剂或增稠剂以改善加工性能，有助于提高生产效率，优化生产工艺。同时该粘度范围内的底涂浆料兼具稳定性、流动性与粘结性，既能提高底涂层的粘结力，又能够实现均匀涂覆，有利于提高底涂层的批次稳定性。
在任意实施方式中，所述溶剂为有机溶剂。
在任意实施方式中，所述溶剂选自N-甲基吡咯烷酮、N,N-二甲基丙酰胺、N,N-二乙基丙酰胺、N,N-二丙基丙酰胺、N,N-二丁基丙酰胺、N,N-二甲基乙基丙酰胺以及3-丁氧基-N-甲基丙酰胺中的一种或多种。
本申请的第五方面提供一种底涂层的制备方法，包括以下步骤：
将底涂浆料凹版涂布在集流体表面，所述底涂浆料为本申请中第四方面的底涂浆料；
干燥后得到底涂层，所述底涂层的厚度为1um～3um。
底涂浆料采用凹版涂布在集流体表面，干燥后得到的厚度为1um～3um的底涂层具有更低的膜片电阻，能够保证极片的电学性 能，同时，也能兼顾底涂层的粘结力。
本申请的第六方面提供一种二次电池，包括正极极片、负极极片、隔离膜和电解质，所述负极极片上包括本申请的第五方面的底涂层。
在任意实施方式中，所述二次电池包括锂离子电池、钠离子电池、镁离子电池、钾离子电池中的至少一种。
本申请的第七方面提供一种电池模块，包括本申请的第六方面的二次电池。
本申请的第八方面提供一种电池包，包括本申请的第六方面的二次电池或本申请的第七方面的电池模块。
本申请的第九方面提供一种用电装置，包括选自本申请的第六方面的二次电池、本申请的第七方面的电池模块或本申请的第八方面的电池包中的至少一种。
附图说明
图1是本申请一实施方式的凹版涂布工艺示意图；
图2是本申请一实施方式的二次电池的示意图；
图3是图2所示的本申请一实施方式的二次电池的分解图；
图4是本申请一实施方式的电池模块的示意图；
图5是本申请一实施方式的电池包的示意图；
图6是图5所示的本申请一实施方式的电池包的分解图；
图7是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53盖板；6凹版涂布装置；61压辊；62凹版辊；63集流体；64刮刀；65浆料槽。
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粘结剂、制备方法、电极、电池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。
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。
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)。
电极的导电性是二次电池最重要的研究课题之一，二次电池极片在制备过程中，会在集流体与活性材料层之间涂覆底涂层，提供活性材料层和集流体之间的电导通，进而降低活性材料层与集流体之间的接触电阻，提高电池的性能。现有技术中一般利用粘结剂、导电剂进行底涂层的制备，传统聚偏二氟乙烯粘结剂会使得浆料的粘度大、过滤性差，难以均匀涂布，因此，在浆料制备过程中需要加入分散剂以提高浆料的加工性能。这无疑会使得浆料的生产工序复杂化、影响生产效率且导致各批次间浆料稳定性差。基于上述技术问题，本申请开发出一种聚合物，在底涂浆料中能够发挥粘结剂和分散剂的作用，提高底涂浆料的过滤性和稳定性，有利于提高底涂层的生产效率和生产质量。
基于此，本申请提出了一种含氟聚合物，其包含衍生自式I所示单体的结构单元和衍生自式II所示单体的结构单元，衍生自式I所示单体的结构单元的摩尔含量为70％～90％，基于含氟聚合物的结构单元的总摩尔数计，
Figure PCTCN2022130103-appb-000003
其中，R 1、R 2、R 3各自独立地选自氢、氟、氯、氟取代的C 1-3烷基中的一种或多种，R 4、R 5、R 6各自独立地选自氢、取代或未取代的C 1-5 烷基中的一种或多种，R 7选自取代或未取代的C 1-9烷基。
在本文中，术语“含氟聚合物”是指结构单元中包含氟元素的聚合物。
在本文中，术语“聚合物”一方面包括通过聚合反应制备的化学上均一的、但在聚合度、摩尔质量和链长方面不同的大分子的集合体。该术语另一方面也包括由聚合反应形成的这样的大分子集合体的衍生物，即可以通过上述大分子中的官能团的反应，例如加成或取代获得的并且可以是化学上均一的或化学上不均一的产物。
在本文中，术语“C 1-5烷基”是指仅由碳和氢原子组成的直链或支链烃链基团，基团中不存在不饱和，具有从一至五个碳原子，并且通过单键附接到分子的其余部分。术语“C 1-3烷基”、术语“C 1-9烷基”应相应解释。C 1-5烷基的示例包括但不限于：甲基、乙基、正丙基、1-甲基乙基(异丙基)、丁基、戊基。在一些实施方式中，氟取代的C 1- 3烷基为-CF 3、-CH 3CH 2F、-CH 2FCH 2F。C 1-9烷基的示例包括但不限于：甲基、乙基、正丙基、异丙基、正丁基、仲丁基、叔丁基、正戊基、正己基、正庚基、正辛基、正壬基。
在本文中，术语“取代的”是指该化合物或化学部分的至少一个氢原子被另一种化学部分被取代基取代，其中的取代基各自独立地选自：羟基、巯基、氨基、氰基、硝基、醛基、卤素原子、烯基、炔基、芳基、杂芳基、C 1-6烷基、C 1-6烷氧基。
在本文中，术语“工艺窗口”指能够保证产品质量的工艺区间，包括但不限于温度区间、压力区间、存储时间长度等，可以理解的是工艺窗口越宽，对工艺精度的需求越低。
在一些实施方式中，R 1为氟，R 2、R 3各自独立地选自氢、氟、氯原子、三氟甲基中的一种或多种，R 5、R 6各自独立地选自氢、甲基中的一种或两种。
在一些实施方式中，式I所示单体选自氟乙烯、偏二氟乙烯、四氟乙烯、三氟氯乙烯、六氟丙烯中的一种或多种。
在一些实施方式中，式II所示单体选自丙烯酸甲酯、丙烯酸乙 酯、丙烯酸丁酯、丙烯酸异戊酯、丙烯酸异辛酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、丙烯酸羟乙酯、丙烯酸羟丙酯中的一种或多种。
在一些实施方式中，聚合物包含一种或多种衍生自式I所示单体的结构单元。在一些实施方式中，聚合物包含一种或多种衍生自式II所示单体的结构单元。在一些实施方式中，聚合物包括但不限于偏二氟乙烯-丙烯酸甲酯共聚物、偏二氟乙烯-丙烯酸乙酯共聚物、偏二氟乙烯-丙烯酸丁酯共聚物、偏二氟乙烯-丙烯酸异戊酯共聚物、偏二氟乙烯-丙烯酸异辛酯共聚物、偏二氟乙烯-甲基丙烯酸甲酯共聚物、偏二氟乙烯-甲基丙烯酸乙酯共聚物、偏二氟乙烯-丙烯酸羟乙酯共聚物、偏二氟乙烯-丙烯酸羟丙酯共聚物、偏二氟乙烯-四氟乙烯-丙烯酸丁酯共聚物、偏二氟乙烯-四氟丙烯-丙烯酸甲酯共聚物、偏二氟乙烯-氟乙烯-丙烯酸丁酯共聚物、偏二氟乙烯-三氟氯乙烯-丙烯酸丁酯共聚物、偏二氟乙烯-六氟丙烯-丙烯酸丁酯共聚物、偏二氟乙烯-六氟丙烯-丙烯酸甲酯共聚物、偏二氟乙烯-六氟丙烯-丙烯酸异辛酯共聚物。
在一些实施方式中，衍生自式I所示单体的结构单元的摩尔含量可选自70％、75％、80％、85％或90％，基于含氟聚合物中结构单元的总摩尔数计。
衍生自式I所示单体的结构单元中的氟元素与集流体表面的羟基或/和羧基能够形成氢键作用，使得底涂层具有较好的粘结力，不易在制造使用过程中发生脱落的现象，导致安全事故；衍生自式II所示单体的结构单元能够有效降低含氟聚合物的氟含量，使得衍生自式I所示单体的结构单元的质量含量在70％～90％，有助于调整浆料粘度，改善氟元素导致的底涂浆料粘度过大的现象，提高浆料的工艺性。
本申请提供的含氟聚合物相比于现有技术中常用的聚二氟乙烯粘结剂使得浆料的粘度有所下降，过滤性有所提高，改善了底涂浆料的可加工性，使得底涂浆料在无需添加分散剂的情况下就能够满足底涂浆料的生产需求，有利于优化底涂浆料的生产工艺和提高其生产品质。
在一些实施方式中，衍生自式II所示单体的结构单元的摩尔含量为10％～30％，基于含氟聚合物中结构单元的总摩尔数计。在一些实施方式中，衍生自式II所示单体的结构单元的摩尔含量可选为12％、15％、18％、20％、22％、25％、30％中的任意一种，基于含氟聚合物中结构单元的总摩尔数计。
基于含氟聚合物的结构单元的总摩尔含量计，衍生自式II所示单体的结构单元的摩尔含量为10％～30％时，含氟聚合物的粘度适宜，使得极片具有良好的粘结力，同时适宜的粘度使得浆料具有良好的流动性和过滤性，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
在一些实施方式中，含氟聚合物的重均分子量为40万～50万。在一些实施方式中，含氟聚合物的重均分子量可选为43万、45万、48万中的任意一种。
在本文中，术语“重均分子量”是指聚合物中用不同分子量的分子所占的重量分数与其对应的分子量乘积的总和。
在本申请中，聚合物的重均分子量的测试可以选用本领域已知的方法进行测试，例如采用凝胶色谱法进行测试，如采用Waters 2695 Isocratic HPLC型凝胶色谱仪(示差折光检测器2141)进行测试。在一些实施方式中，测试方法为以质量分数为3.0％的聚苯乙烯溶液试样做参比，选择匹配的色谱柱(油性：Styragel HT5DMF7.8*300mm+Styragel HT4)。用纯化后的N-甲基吡咯烷酮(NMP)溶剂配置3.0％的含氟聚合物胶液，配置好的溶液静置一天，备用。测试时，先用注射器吸取四氢呋喃，进行冲洗，重复几次。然后吸取5ml实验溶液，排除注射器中的空气，将针尖擦干。最后将试样溶液缓缓注入进样口。待示数稳定后获取数据，读取重均分子量。
重均分子量在40万～50万的含氟聚合物粘度适宜，使得极片具有良好的粘结力，同时适宜的粘度有利于后续的涂覆工作，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
本申请的一个实施方式中，提供一种含氟聚合物的制备方法，包括以下步骤：
在可聚合条件下，将至少一种式I所示单体和至少一种式II所示单体进行聚合反应，式I所示单体的摩尔含量为70％～90％，基于式I所示单体和式II所示单体的总摩尔数计，
Figure PCTCN2022130103-appb-000004
其中，R 1、R 2、R 3各自独立地选自氢、氟、氯、氟取代的C 1-3烷基中的一种或多种，R 4、R 5、R 6各自独立地选自氢、取代或未取代的C 1-5烷基中的一种或多种，R 7选自取代或未取代的C 1-9烷基。
在本文中，术语“可聚合条件”是指包括本领域技术人员选择的温度、压力、反应物浓度、任选的溶剂/稀释剂、反应物混合/添加参数的那些条件，有助于一种或多种单体在至少一个聚合反应器内反应的其他条件。
该方法制备出的含氟聚合物相比于传统粘结剂能够提高底涂浆料的稳定性能和粘结性能，显著拓宽了底涂浆料的工艺窗口，改善了底涂浆料的使用性能。
在一些实施方式中，R 1为氟，R 2、R 3各自独立地选自氢、氟、氯、三氟甲基中的一种或多种，R 5、R 6各自独立地选自氢、甲基中的一种或两种。
在一些实施例中，式II所示单体的摩尔含量为10％～30％，基于式I所示单体和式II所示单体的总摩尔数计。在一些实施方式中，衍生自式II所示单体的结构单元的摩尔含量可选为12％、15％、18％、20％、22％、25％、30％中的任意一种，基于式I所示单体和式II所示单体的总摩尔数计。
基于含氟聚合物的结构单元的总摩尔含量计，衍生自式II所示单体的结构单元的摩尔含量为10％～30％时，含氟聚合物的粘度适宜，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
在一些实施方式中，聚合反应包括第一段聚合和第二段聚合，
第一段聚合：向反应容器内加入引发剂、第一乳化剂、至少一种式I所示单体以及水性介质进行第一段聚合，在第一段聚合中连续送入式I所示单体；
第二段聚合：反应一段时间后，向反应容器内加入引发剂、第二乳化剂、至少一种式II所示单体以及水性介质进行第二段聚合，在第二段聚合中连续送入式I所示单体。
在本文中，术语“连续送入”是指缓慢地、小量地、增量地添加单体。
本申请提供的方法通过首先连续送入式I所示单体形成含氟链段，保证含氟聚合物具有较高的粘结性能；再通入式II所示单体以减少含氟链段与外界环境的接触，能够有效降低浆料的粘度。该方法制备出的含氟聚合物相比于通过将单体全部通入反应容器同时聚合制备的含氟聚合物更能有效提高底涂浆料的稳定性和粘结性能，进一步拓宽底涂浆料的工艺窗口和储存性能，有助于降低底涂层的制造成本。
在一些实施方式中，第一段聚合中提供的引发剂和第二段聚合中提供的引发剂均为过硫酸盐，第一段聚合中提供的引发剂的质量百分比为0.05％～0.1％，基于所述式I所示单体和式II所示单体的总质量计；所述第二段聚合中提供的引发剂的质量百分比为0.05％～0.1％，基于所述式II所示单体的质量计。
在一些实施方式中，引发剂过硫酸盐可选为过硫酸钾，过硫酸钾在60℃以上有效地分解，产生自由基离子或离子自由基，适宜作为乳液聚合的引发剂。
在一些实施方式中，第一段聚合中提供的引发剂的质量百分比为0.05％、0.07％、0.09％或0.1％，基于所述式I所示单体和式II所示单体的总质量计。
在一些实施方式中，第二段聚合中提供的引发剂的质量百分比为0.05％、0.07％、0.09％或0.1％，基于式II所示单体的质量计。
在一些实施方式中，第一乳化剂的质量百分比为0.2％～0.7％，基于式I所示单体和式II所示单体的总质量计。在一些实施方式中，第一乳化剂的质量百分比为0.2％、0.5％或0.7％，基于式I所示单体和式II所示单体的总质量计。
在一些实施方式中，第一乳化剂为全氟辛酸碱金属盐。
在一些实施方式中，第二乳化剂的质量百分比为0.5％～1.5％，基于所述式II所示单体的质量计。在一些实施方式中，第二乳化剂的质量百分比为0.5％、0.75％、1.0％、1.25％或1.5％，基于所述式II所示单体的质量计。
在一些实施方式中，第二乳化剂为聚氧乙烯-4-酚基醚硫酸铵盐、壬基酚聚氧乙烯醚硫酸铵盐中的一种或两种。
在一些实施方式中，第一段聚合中提供的水性介质的质量百分比为200％～500％，第二段聚合中提供的水性介质的质量百分比为100％～200％，基于式I所示单体和式II所示单体的总质量计。在一些实施方式中，第一段聚合中提供的水性介质的质量百分比为200％、300％、400％或500％，第二段聚合中提供的水性介质的质量百分比为100％、150％或200％，基于式I所示单体和式II所示单体的总质量计。在一些实施方式中，水性介质为水溶剂，可选为去离子水或去离子水与其他亲水性溶剂，如醇或乙酸乙酯的混合物。
在一些实施方式中，第一段聚合的反应压力为5.5～7.5MPa，反应温度为75℃～85℃。在一些实施方式中，第一段聚合的反应压力为5.5MPa、6.5MPa或7.5MPa，反应温度为75℃、80℃或85℃。
在一些实施方式中，第二段聚合的反应压力为4.5～6.5MPa，反应温度为86℃～95℃。在一些实施方式中，第二段聚合的反应压力为4.5MPa、5.5MPa或6.5MPa，反应温度为86℃、90℃或95℃。
在一些实施方式中，第一段聚合中通入的式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的90％～95％，第二段聚合反应中通入的式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的5％～10％。在一些实施方式中，第一段聚合中通入的 式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的90％、92％或95％，第二段聚合反应中通入的式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的5％、7％或10％。
在一些实施方式中，反应一段时间后，向反应容器内提供引发剂、第二乳化剂、至少一种式II所示单体以及水性介质进行第二段聚合包括：
向反应容器内，加入引发剂后，再加入包含引发剂、第二乳化剂、至少一种式II所示单体以及水性介质在内的预混液。
本申请的一个实施方式中，提供一种任意实施方式中的含氟聚合物在二次电池中的应用，可选地，二次电池包括锂离子电池、钠离子电池、镁离子电池、钾离子电池中的至少一种。在一些实施方式中，含氟聚合物作为粘结剂在二次电池中的应用。在一些实施方式中，含氟聚合物作为底涂层的粘结剂在二次电池中的应用。
[底涂浆料]
本申请的一个实施方式中，提供一种底涂浆料，包括粘结剂、导电剂和溶剂，粘结剂包含任意实施方式中的含氟聚合物。
在本文中，术语“粘结剂”是指在分散介质中形成胶体溶液或胶体分散液的化学化合物、聚合物或混合物。
在本申请中，术语“导电剂”是起到收集微电流作用的物质，包括但不限于超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，溶剂为有机溶剂。
有机溶剂是指包含碳原子的有机化合物作为溶剂。有机溶剂能够溶解一些不溶于水的物质。以有机溶剂作为底涂层的溶剂，使得底涂浆料适宜制备负极极片的底涂层，该底涂层在负极膜层制备过程中不容易产生溶解，具有高的稳定性。
在一些实施方式中，溶剂选自N-甲基吡咯烷酮、N,N-二甲基丙酰胺、N,N-二乙基丙酰胺、N,N-二丙基丙酰胺、N,N-二丁基丙酰胺、N,N-二甲基乙基丙酰胺以及3-丁氧基-N-甲基丙酰胺中的一种或多种。
该底涂浆料易于加工制备且均匀性好，有助于提高电池产能。
在一些实施方式中，粘结剂的质量分数为0.5％～5％，基于导电剂的质量计。在一些实施方式中，粘结剂的质量含量可选为0.5％、1.0％、2.0％、4.0％、5.0％中的任意一种，基于导电剂的质量计。
粘结剂的质量含量在合适范围时，使得底涂层与集流体之间具有足够的粘结力，避免在电芯使用过程中，底涂层脱落的风险；同时粘结剂的质量含量在合适范围内，使得底涂浆料具有合适的粘度，使得浆料具有良好的流动性和过滤性，利于后续的涂覆工作。
在一些实施方式中，底涂浆料的固含量为15％～30％，底涂浆料的粘度为100mPa·s～1000mPa·s。在一些实施方式中，底涂浆料的固含量为15％～30％时，底涂浆料的粘度为100mPa·s、200mPa·s、300mPa·s、400mPa·s、500mPa·s、600mPa·s、700mPa·s、800mPa·s、900mPa·s或1000mPa·s。
底涂浆料的粘度在合适范围内，一方面利于后续的涂覆和烘干工作；另一方面合适的粘度可以提高浆料的稳定性，使得浆料具有良好的流动性和过滤性。
在本申请中，含氟聚合物的底涂浆料的粘度可以选用本领域已知的方法进行测试，例如采用旋转粘度剂进行测试。
固含量为15％～30％的底涂浆料的粘度为100mPa·s～1000mPa·s，这使得含氟聚合物制备的底涂浆料无需添加额外的分散剂或增稠剂以改善加工性能，有助于提高生产效率，优化生产工艺。同时该粘度范围内的底涂浆料兼具稳定性、流动性与粘结性，既能提高底涂层的粘结力，又能够实现均匀涂覆，有利于提高底涂层的批次稳定性。
本申请的一个实施方式中，提供一种底涂层的制备方法，包括以下步骤：
将底涂浆料凹版涂布在集流体表面，底涂浆料为任意实施方式中的底涂浆料；所述底涂浆料干燥后得到底涂层。
在一些实施方式中，凹版涂布工艺如图1所示，凹版涂布装置6中的凹版辊62部分浸入浆料槽65的浆料中，凹版辊62转动带动浆 料运动，刮刀64刮除凹版辊62平滑处的浆料，存留在凹版辊62表面凹坑中的浆料在压辊61的压力作用下，将凹坑中的浆料转移到集流体63的表面，其中凹版辊62的旋转方向与压辊61的运动方向相反。可以根据需要的底涂层厚度调整凹版辊62表面凹坑的深度，凹坑的深度可选为10-100um。
通过凹版涂布制备的底涂层表面粗糙，能够通过机械铆合提高底涂层与膜层或者集流体间的粘结性能，使得极片具有更好的粘结力。
在一些实施方式中，底涂层的厚度为1um～3um。
底涂浆料采用凹版涂布在集流体表面，干燥后得到的厚度为1um～3um的底涂层具有优异的粘结力和低的膜片电阻，能够保证极片的机械性能和电化学性能。
本申请的一个实施方式中，提供一种二次电池，包括正极极片、负极极片、隔离膜和电解质，所述负极极片上包括任意实施方式中所述的底涂层。在一些实施方式中，所述二次电池包括锂离子电池、钠离子电池、镁离子电池、钾离子电池中的至少一种。
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。电解质在正极极片和负极极片之间起到传导离子的作用。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，同时可以使离子通过。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及 银合金等)形成在高分子材料基材(如聚丙烯(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)等的基材)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。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。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、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(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、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中的至少一种。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(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-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用 于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的底涂层和设置在底涂层上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(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)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。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。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备底涂层的组分，例如将含氟聚合物、导电剂分散于N-甲基-2-吡咯烷酮，形成底涂浆料；将底涂浆料凹版涂布在铜箔集流体表面上，得到具有底涂层的集流体。将上述用于制备负极膜层的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在具有底涂层的集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、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、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对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。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，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。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图2是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图3，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能够盖设于所述开口，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封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，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一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图4是作为一个示例的电池模块4。参照图4，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。
在一些实施方式中，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为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图5和图6是作为一个示例的电池包1。参照图5和图6，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能够盖设于下箱体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。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、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。所述用电装置可以包括移动设备(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，但不限于此。
作为所述用电装置，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。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二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。 该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
一、制备方法
实施例1
1)含氟聚合物的制备
将26kg的去离子水、37.3g的全氟辛酸钠盐、112g的5％浓度的过硫酸钾溶液，其中去离子水的电导率小于等于2μs/cm，依次加入反应釜内，关闭反应釜；
釜内抽真空，充氮气，重复操作至反应釜内氧气浓度小于100ppm；
向反应釜内通入偏二氟乙烯单体，釜内压力7.5MPa，釜内升温至85℃时开始反应，反应过程中不断通入偏二氟乙烯单体维持釜内反应压力不变；
将11.2kg的去离子水、29.8g的聚氧乙烯-4-酚基醚硫酸铵盐、23.3mol的丙烯酸丁酯加入搅拌罐内搅拌均匀，其中去离子水的电导率小于等于2μs/cm，得预混液；
通入偏二氟乙烯单体总量为66.5mol时，加入44.8g的5％浓度的过硫酸铵，调整反应压力为6.0MPa，升温至90℃，向反应釜内缓慢加入预混液，预混液的全部加入时间2.5小时，与此同时逐渐通入余下的3.5mol偏二氟乙烯单体；
釜内压力降低到0.2MPa时，停止反应；
冷却至室温，反应产物经凝聚、洗涤、分离、干燥、粉碎得到偏二氟乙烯-丙烯酸丁酯共聚物粘结剂。
2)制备底涂浆料
称取5.88kg的导电炭黑、0.12kg的偏二氟乙烯-丙烯酸丁酯共聚物粘结剂依次加入搅拌罐内，设定搅拌速度为300转/分钟，搅拌10分钟；
称取14kg的N-甲基吡咯烷酮加入到搅拌罐内，设定搅拌速度为1200转/分钟，搅拌120分钟；
再称取10kg的N-甲基吡咯烷酮加入到搅拌罐内，设定搅拌速度为1500转/分钟，搅拌120分钟；
采用200目滤网过滤上述浆料，得到底涂浆料。
3)底涂层的制备
将底涂浆料利用图1所示的凹版涂布装置进行涂布，先将底涂浆料注入到浆料槽中，通过凹版辊转动携带底涂浆料，在经刮刀刮除平滑处的底涂浆料后，剩余底涂浆料仅存留在凹版辊表面的凹坑中，凹坑的深度为50um，在压辊的压力作用下，可以将凹坑中的底涂浆料转移到铜箔集流体基材的表面，烘干得到厚度为2um的底涂层。
4)负极极片的制备
石墨材料、导电剂碳黑、丁苯粘结剂、羧甲基纤维素钠、N-甲基吡咯烷酮(NMP)按重量比为97.15：0.04：1.95：0.5：0.36搅拌混合均匀，得到负极浆料，浆料的固含量为64％；
负极浆料均匀涂覆于底涂层上，之后经过烘干、冷压、分切，得到负极极片。
实施例2～实施例3中调节含氟聚合物中各单体的配比，其他参数同实施例1保持一致，具体参数见表1和表2。
实施例4～实施例7中调整含氟聚合物合成中的反应条件，使得含氟聚合物具有不同的重均分子量，其他参数同实施例1保持一致，具体参数见表1和表2。具体而言，实施例4中重均分子量为30万的含氟聚合物的制备方法与实施例1步骤基本相同，区别在于将5％浓度的过硫酸钾溶液添加量调整为99.00g。
实施例5中重均分子量为40万的含氟聚合物的制备方法与实施例1步骤基本相同，区别在于将5％浓度的过硫酸钾溶液添加量调整 为99.45g。
实施例6中重均分子量为50万的含氟聚合物的制备方法与实施例1步骤基本相同，区别在于将反应温度调整为80℃，5％浓度的过硫酸钾溶液添加量调整为89.45g。
实施例7中重均分子量为60万的含氟聚合物的制备方法与实施例1步骤基本相同，区别在于将反应温度调整为80℃，5％浓度的过硫酸钾溶液添加量调整为81.00g。
实施例8～实施例11中调整底涂浆料中粘结剂的质量分数，其他参数同实施例1保持一致，具体参数见表1和表2。
实施例12～实施例15中，调整底涂浆料的固含量，其他参数同实施例1保持一致，具体参数见表1和表2。
实施例16中，将丙烯酸乙酯单体替换成丙烯酸异辛酯单体，其他参数同实施例1，具体参数参见表1和表2。
实施例17中，采用刮刀涂覆法制备底涂层，其他方法同实施例1，具体参数参见表1和表2。
实施例18中，其制备方法与实施例1保持一致，区别在于底涂层中的粘结剂为传统方法制备的偏二氟乙烯-丙烯酸丁酯共聚物，其合成方法为：
将37.2kg的去离子水(电导率小于等于2μs/cm)、37.3g的全氟辛酸钠盐、112g的5％浓度的过硫酸钾溶液、44.8g的5％浓度的过硫酸铵溶液、29.8g的聚氧乙烯-4-酚基醚硫酸铵盐，依次加入反应釜内，关闭反应釜；
釜内抽真空，充氮气，重复操作至反应釜内氧气浓度小于100ppm；
向反应釜内通入偏二氟乙烯单体、23.3mol丙烯酸丁酯的至釜内压力7.5MPa；
釜内升温至85℃开始反应，反应过程中不断通入偏二氟乙烯单体维持釜内反应压力不变，通入的偏二氟乙烯单体的摩尔数为70mol；
釜内压力降至0.2MPa时停止反应；
冷却至室温，经凝聚、洗涤、分离、干燥、粉碎得到含氟聚合物， 即偏二氟乙烯-丙烯酸丁酯共聚物。
对比例1中，其制备方法与实施例1保持一致，区别在于对比例1中以偏二氟乙烯聚合物作为底涂浆料的粘结剂，其为法国阿科玛公司的HSV900型号。
对比例2与对比例1基本相同，区别在于调整了底涂层的制备方法，具体的制备方法为：
将底涂浆料采用刮刀涂覆在铜箔集流体基材的表面，烘干得到厚度为2um的底涂层。
对比例3～对比例4中调节了含氟聚合物中各单体的配比，其他参数同实施例1保持一致，具体参数见表1和表2。
上述实施例1～实施例18、对比例1～对比例4的底涂浆料和涂层的相关参数如下述表1和表2所示。
另外，将上述实施例1～实施例18和对比例1～对比例4中得到的底涂浆料和涂层进行性能测试。
二、测试方法
1、重均分子量测试
采用Waters 2695 Isocratic HPLC型凝胶色谱仪(示差折光检测器2141)。以质量分数为3.0％的聚苯乙烯溶液试样做参比，选择匹配的色谱柱(油性：Styragel HT5DMF7.8×300mm+Styragel HT4)。用纯化后的N-甲基吡咯烷酮(NMP)溶剂配置3.0％的含氟聚合物溶液，配置好的溶液静置一天，备用。测试时，先用注射器吸取四氢呋喃，进行冲洗，重复几次。然后吸取5ml实验溶液，排除注射器中的空气，将针尖擦干。最后将试样溶液缓缓注入进样口。待示数稳定后获取数据，读取重均分子量。
2、底涂浆料粘度测试
使用旋转粘度剂测量底涂浆料的粘度。选取合适的转子，固定好粘度计转子，将底涂浆料放置于粘度计转子下方，浆料恰好淹没转子的刻度线，仪器型号：上海方瑞NDJ-5S，转子为62#，转速为30转/分钟，可测量浆料的粘度范围为0～1000mPa·s；转子为63#，转速为 30转/分钟，可测量浆料的粘度范围为0～2000mPa·s)，测试温度：25℃，测试时间为5分钟，待示数稳定读取数据。
3、底涂浆料过滤性能测试
取500ml烧杯置于200目滤网支架下端，取底涂浆料500ml，置于滤网中过滤，当烧杯中浆料体积到达300ml的过滤时间低于120s，表明浆料的过滤性能好，判定为“Y”；若浆料不能在120s以内透过滤网，表明浆料的过滤性能差，判定为“N”。
4、底涂浆料固含量以及静置24小时之后固含量差值
取铜箔于失重率测定仪内称重，记为M0，清零失重率测定仪；
取底涂浆料，少量涂覆于铜箔上，然后放入失重率测定仪内称重，记为M1；
合上设备，开始烘干；
结束后，记录称重数据，记录为M2，并计算固含量，固含量为(M2-M0)/(M1-M0)；
以同样的方法测量静置24小时后上层和下层底涂浆料的固含量，以下层底涂浆料的固含量减上层底涂浆料的固含量作为底涂浆料静置24小时之后固含量的差值。
5、极片的粘结力
参考GB-T2790-1995国标《胶粘剂180°剥离强度实验方法》，本申请实施例和对比例的粘结力测试过程如下：用刀片截取宽度为30mm，长度为150mm的试样，将专用双面胶贴于钢板上，胶带宽度20mm，长度100mm。将前面截取的极片试样的负极膜层面贴在双面胶上，后用2kg压辊沿同一个方向滚压三次。将宽度与极片等宽，长度为250mm的纸带固定于极片集流体上，并且用皱纹胶固定。打开三思拉力机电源(灵敏度为1N)，指示灯亮，调整限位块到合适位置，将钢板未贴极片的一端用下夹具固定。将纸带向上翻折，用上夹具固定，利用拉力机附带的手动控制器上的“上行”和“下行”按钮调整上夹具的位置。然后进行测试并读取数值，拉伸速度为50mm/min。将极片受力平衡时的力除以胶带的宽度作为单位长度的负 极极片的粘结力，以表征集流体上的膜层与集流体之间的粘结强度。
6、极片的膜片电阻
在极片左、中、右处裁剪烘干后的极片，裁剪为30mm直径的小圆片。开启元能科技极片电阻仪电源，将其置于极片电阻仪“探头”合适位置，点击“开始”按钮，待示数稳定，读取即可。每个小圆片测试两个位置，最后计算六次测量的平均值，即为该极片的膜层电阻。
7、底涂层的厚度
取光面铜箔放于平面桌面上，铜箔超出桌面约5cm宽，桌面上的铜箔压住防止铜箔移动；
打开万分尺，清零，万分尺购买自日本三丰公司；
于铜箔不同位置依次测试，取五个点求平均值记L1；
铜箔单面进行凹版涂布干燥后放于平面桌面上，铜箔超出桌面约5cm宽，桌面上的铜箔压住防止铜箔移动；
打开万分尺，清零；
于铜箔不同位置依次测试，取五个点求平均值记L2；
底涂层的厚度＝(L2-L1)。
三、结果分析
表1 实施例和对比例的制备参数和结果
Figure PCTCN2022130103-appb-000005
Figure PCTCN2022130103-appb-000006
表2 实施例和对比例的制备参数和结果
Figure PCTCN2022130103-appb-000007
Figure PCTCN2022130103-appb-000008
根据表1结果可知，实施例1-18中的粘结剂均为含氟聚合物，包含衍生自偏二氟乙烯的结构单元、以及衍生自丙烯酸酯的结构单元，该聚合物中衍生自偏二氟乙烯的结构单元的摩尔含量为70％～90％，基于含氟聚合物中结构单元的总摩尔数计。以上述含氟聚合物作为粘结剂均取得了良好的效果，相比于对比例1中的聚偏二氟乙烯，本申请提供的含氟聚合物使得浆料的粘度有所下降，过滤性有所提高，适宜制备底涂层。
从实施例1-3与对比例3、4的对比可见，基于含氟聚合物中所有结构单元的总摩尔含量计，含氟聚合物中衍生自丙烯酸酯的结构单元的摩尔含量为10％～30％时，含氟聚合物的粘度适宜，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
从实施例4-7的对比可见，含氟聚合物的重均分子量为40万～50万时，含氟聚合物的粘度适宜，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
从实施例8-11可见，含氟聚合物的质量分数为0.5％～5％，基于所述导电剂的质量计时，含氟聚合物的粘度适宜，适于制备均匀的底涂层，能够综合地改善浆料的工艺性和粘结性，兼顾底涂层的加工性能和使用性能。
从实施例12-15可见，含氟聚合物的质量分数为0.5％～5％、固含量为15％～30％的底涂浆料的粘度为100mPa·s-1000mPa·s，这使得含氟聚合物制备的底涂浆料无需添加额外的分散剂或增稠剂以改善加工性能，这有助于减少浆料批次间的差异性，提高生产效率，优化生产工艺。
从实施例1-16与实施例18的对比可见，通过本申请公开的方法制备的含氟聚合物，相比于传统方法合成的含氟共聚物，更能有效改善浆料的稳定性，扩展浆料涂覆的工艺窗口，改善浆料的加工性能。
从实施例1-16与实施例17的对比可见，采用凹版涂布制备 的底涂层相比于现有技术中常用的刮刀法制备的底涂层，具有更高的粘结力。
从实施例1-16与对比例2的对比可见，本申请中采用凹版涂布制备的底涂层与现有技术中包含传统粘结剂的浆料未采用凹版涂布制备的底涂层具有相当的极片粘结力，展现出了优异的应用前景。
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。

Claims (32)

  1. 一种含氟聚合物，其特征在于，其包含衍生自式I所示单体的结构单元和衍生自式II所示单体的结构单元，所述衍生自式I所示单体的结构单元的摩尔含量为70％～90％，基于所述含氟聚合物的总摩尔数计，
    Figure PCTCN2022130103-appb-100001
    其中，R 1、R 2、R 3各自独立地选自氢、氟、氯或氟取代的C 1-3烷基，R 4、R 5、R 6各自独立地选自氢或取代或未取代的C 1-5烷基，R 7选自取代或未取代的C 1-9烷基。
  2. 根据权利要求1中所述的含氟聚合物，其特征在于，所述R 1为氟，R 2、R 3各自独立地选自氢、氟、氯、三氟甲基中的一种或多种，R 5、R 6各自独立地选自氢、甲基中的一种或两种。
  3. 根据权利要求1或2所述的含氟聚合物，其特征在于，所述衍生自式II所示单体的结构单元的摩尔含量为10％～30％，基于所述含氟聚合物的结构单元的总摩尔数计。
  4. 根据权利要求1至3中任一项所述的含氟聚合物，其特征在于，所述含氟聚合物的重均分子量为40万～50万。
  5. 根据权利要求1所述的含氟聚合物，其特征在于，所述式I所示单体选自氟乙烯、偏二氟乙烯、四氟乙烯、三氟氯乙烯、六氟丙烯中的一种或多种。
  6. 根据权利要求1至5中任一项所述的含氟聚合物，其特征在 于，所述式II所示单体选自选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯、丙烯酸异戊酯、丙烯酸异辛酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、丙烯酸羟乙酯、丙烯酸羟丙酯中的一种或多种。
  7. 一种含氟聚合物的制备方法，其特征在于，包括以下步骤：
    在可聚合条件下，将至少一种式I所示单体和至少一种式II所示单体进行聚合反应，所述式I所示单体的摩尔含量为70％～90％，基于式I所示单体和式II所示单体的总摩尔数计，
    Figure PCTCN2022130103-appb-100002
    其中，R 1、R 2、R 3各自独立地选自氢、氟、氯或氟取代的C 1-3烷基，R 4、R 5、R 6各自独立地选自氢、取代或未取代的C 1-5烷基，R 7选自取代或未取代的C 1-9烷基。
  8. 根据权利要求7所述的制备方法，其特征在于，所述R 1为氟，R 2、R 3各自独立地选自氢、氟、氯、三氟甲基中的一种或多种，R 5、R 6各自独立地选自氢、甲基中的一种或两种。
  9. 根据权利要求7或8所述的制备方法，其特征在于，所述式II所示单体的摩尔含量为10％～30％，基于式I所示单体和式II所示单体的总摩尔数计。
  10. 根据权利要求7至9中任一项所述的制备方法，其特征在于，所述聚合反应包括第一段聚合和第二段聚合，
    第一段聚合：向反应容器内加入引发剂、第一乳化剂、至少一种式I所示单体以及水性介质进行第一段聚合，在所述第一段聚合中连续送入式I所示单体；
    第二段聚合：反应一段时间后，向反应容器内加入引发剂、第二 乳化剂、至少一种式II所示单体以及水性介质进行第二段聚合，在所述第二段聚合中连续送入式I所示单体。
  11. 根据权利要求10所述的制备方法，其特征在于，所述第一段聚合中通入的式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的90％～95％，所述第二段聚合反应中通入的式I所示单体的质量为聚合反应中所供给的式I所示单体的总质量的5％～10％。
  12. 根据权利要求10或11所述的制备方法，其特征在于，所述第一段聚合中提供的引发剂和所述第二段聚合中提供的引发剂均为过硫酸盐，所述第一段聚合中提供的引发剂的质量百分比为0.05％～0.1％，基于所述式I所示单体和式II所示单体的总质量计；所述第二段聚合中提供的引发剂的质量百分比为0.05％～0.1％，基于所述式II所示单体的质量计。
  13. 根据权利要求10至12中任一项所述的制备方法，其特征在于，所述第一乳化剂的质量百分比为0.2％～0.7％，基于所述式I所示单体和式II所示单体的总质量计。
  14. 根据权利要求10至13中任一项所述的制备方法，其特征在于，所述第二乳化剂的质量百分比为0.5％～1.5％，基于所述式II所示单体的质量计。
  15. 根据权利要求10至14中任一项所述的制备方法，其特征在于，所述第一段聚合中提供的水性介质的质量百分比为200％～500％，所述第二段聚合中提供的水性介质的质量百分比为100％～200％，基于所述式I所示单体和式II所示单体的总质量计。
  16. 根据权利要求10至15中任一项所述的制备方法，其特征在于，所述第一段聚合的反应压力为5.5～7.5MPa，反应温度为75℃～85℃。
  17. 根据权利要求10至16中任一项所述的制备方法，其特征在于，所述第二段聚合的反应压力为4.5～6.5MPa，反应温度为86℃～95℃。
  18. 根据权利要求10至17中任一项所述的制备方法，其特征在于，所述反应一段时间后，向反应容器内提供引发剂、第二乳化剂、至少一种式II所示单体以及水性介质进行第二段聚合包括：
    向反应容器内，加入引发剂后，再加入包含引发剂、第二乳化剂、至少一种式II所示单体以及水性介质在内的预混液。
  19. 根据权利要求10至18中任一项所述的制备方法，其特征在于，所述第一乳化剂为全氟辛酸碱金属盐。
  20. 根据权利要求10至19中任一项所述的制备方法，其特征在于，所述第二乳化剂为聚氧乙烯-4-酚基醚硫酸铵盐、壬基酚聚氧乙烯醚硫酸铵盐中的一种或两种。
  21. 权利要求1至6中任一项所述的含氟聚合物在二次电池中的应用。
  22. 一种底涂浆料，包括粘结剂、导电剂和溶剂，其特征在于，所述粘结剂包含权利要求1至6中任一项所述的含氟聚合物。
  23. 根据权利要求22所述的底涂浆料，其特征在于，所述粘结 剂的质量分数为0.5％～5％，基于所述导电剂的质量计。
  24. 根据权利要求22或23所述的底涂浆料，其特征在于，所述底涂浆料的固含量为15％～30％，所述底涂浆料的粘度为100mPa·s～1000mPa·s。
  25. 根据权利要求22至24中任一项所述的底涂浆料，其特征在于，所述溶剂为有机溶剂。
  26. 根据权利要求22至25中任一项所述的底涂浆料，其特征在于，所述溶剂选自N-甲基吡咯烷酮、N,N-二甲基丙酰胺、N,N-二乙基丙酰胺、N,N-二丙基丙酰胺、N,N-二丁基丙酰胺、N,N-二甲基乙基丙酰胺以及3-丁氧基-N-甲基丙酰胺中的一种或多种。
  27. 一种底涂层的制备方法，其特征在于，包括以下步骤：
    将权利要求22至26中任一项所述的底涂浆料凹版涂布在集流体表面；所述底涂浆料干燥后得到底涂层。
  28. 一种二次电池，其特征在于，包括正极极片、负极极片、隔离膜和电解液，所述负极极片上包括权利要求27所述的制备方法制备的底涂层。
  29. 根据权利要求28所述的二次电池，其特征在于，所述二次电池包括锂离子电池、钠离子电池、镁离子电池、钾离子电池中的至少一种。
  30. 一种电池模块，其特征在于，包括权利要求28或29所述的二次电池。
  31. 一种电池包，其特征在于，包括权利要求28或29所述的二次电池、权利要求30所述的电池模块中的至少一种。
  32. 一种用电装置，其特征在于，包括选自权利要求28或29所述的二次电池、权利要求30所述的电池模块或权利要求31所述的电池包中的至少一种。
PCT/CN2022/130103 2022-11-04 2022-11-04 含氟聚合物、底涂浆料、二次电池、及用电装置 WO2024092809A1 (zh)

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* Cited by examiner, † Cited by third party
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JPH04222808A (ja) * 1990-03-23 1992-08-12 Atochem North America Inc 亀裂抵抗性コーティング樹脂
CN104725545A (zh) * 2013-12-23 2015-06-24 浙江蓝天环保高科技股份有限公司 一种新型高粘结性偏氟乙烯共聚物
CN104725544A (zh) * 2013-12-20 2015-06-24 浙江蓝天环保高科技股份有限公司 一种新型高粘结性偏氟乙烯共聚物
CN110660957A (zh) * 2018-12-29 2020-01-07 宁德时代新能源科技股份有限公司 一种电极极片和电化学装置
CN110915027A (zh) * 2017-07-07 2020-03-24 Ppg工业俄亥俄公司 用于锂离子储电器件的电极粘结剂浆料组合物

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04222808A (ja) * 1990-03-23 1992-08-12 Atochem North America Inc 亀裂抵抗性コーティング樹脂
CN104725544A (zh) * 2013-12-20 2015-06-24 浙江蓝天环保高科技股份有限公司 一种新型高粘结性偏氟乙烯共聚物
CN104725545A (zh) * 2013-12-23 2015-06-24 浙江蓝天环保高科技股份有限公司 一种新型高粘结性偏氟乙烯共聚物
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