WO2024244366A1 - 含氟聚合物、制备方法、负极浆料、负极极片、二次电池及用电装置 - Google Patents

含氟聚合物、制备方法、负极浆料、负极极片、二次电池及用电装置 Download PDF

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WO2024244366A1
WO2024244366A1 PCT/CN2023/136775 CN2023136775W WO2024244366A1 WO 2024244366 A1 WO2024244366 A1 WO 2024244366A1 CN 2023136775 W CN2023136775 W CN 2023136775W WO 2024244366 A1 WO2024244366 A1 WO 2024244366A1
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monomer represented
formula
fluorine
negative electrode
containing polymer
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French (fr)
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冯伟
刘会会
张帅
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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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
    • 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
    • C08F220/20—Esters of polyhydric alcohols or phenols, e.g. 2-hydroxyethyl (meth)acrylate or glycerol mono-(meth)acrylate
    • 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
    • C08F220/04—Acids; Metal salts or ammonium salts thereof
    • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a fluorine-containing polymer, a preparation method, a negative electrode slurry, a negative electrode plate, a secondary battery and an electrical device.
  • secondary batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • the pole piece is an important component of the secondary battery and has a key impact on the performance of the secondary battery.
  • a binder is usually added to the pole piece to bind the active material.
  • the binder has a large molecular weight and poor dispersibility in the solvent, which often causes the agglomeration of the active material, resulting in a decrease in battery performance.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a fluorine-containing polymer that can provide a certain adhesive force while improving the dispersibility of the slurry, reducing the rebound rate of the pole piece and the DC impedance of the battery.
  • 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, a structural unit derived from a monomer represented by formula II, and a structural unit derived from a monomer represented by formula III.
  • R1 , R2 , and R3 each independently include hydrogen, fluorine, chlorine, and C1-3 alkyl containing at least one fluorine atom;
  • R4 , R5 , R6 , R8 , R9 , and R10 each independently include hydrogen, substituted or unsubstituted C1-5 alkyl; and
  • R7 includes C1-10 alkyl containing at least one hydroxyl group.
  • the fluorinated polymer provided in the present application can act as both a binder and a dispersant; it can provide effective bonding to the negative electrode active material, and can effectively improve the filterability of the negative electrode slurry, reduce the added content of the dispersant in the negative electrode slurry, and thus effectively increase the load of the negative electrode active material and reduce the internal resistance of the battery.
  • the structural unit derived from the monomer shown in formula I can effectively ensure the bonding performance of the fluorinated polymer
  • the structural unit derived from the monomer shown in formula II can effectively improve the dispersibility of the fluorinated polymer
  • the carboxyl, ester and hydroxyl functional groups in the fluorinated polymer can act as anchoring groups to easily interact with the oxygen-containing functional groups on the negative electrode active material, thereby inhibiting the agglomeration of the negative electrode active material.
  • the hydroxyl groups located on the side chains make the polymer segments easier to move, which can effectively improve the flexibility and dispersibility of the fluorinated polymer, thereby reducing the internal resistance of the battery.
  • the compaction density of the pole piece during the production process usually has a high design value.
  • the negative electrode active materials are mostly layered materials, which are prone to slippage. Therefore, the thickness of the pole piece will often rebound after cold pressing.
  • the increase in the thickness of the pole piece causes the thickness of the battery cell to be higher than the design value, making it difficult to put into the shell; moreover, during the charge and discharge cycle, the expansion of the negative electrode active material will cause the pole piece to rebound further, increasing the expansion force on the battery cell, leaving a safety hazard.
  • the fluorinated polymer provided in this application is effective in improving slurry processing. While improving performance, it can also effectively suppress the rebound of the negative electrode plate, thereby improving battery manufacturing efficiency and safety of use.
  • R 1 in Formula I includes fluorine, and R 2 and R 3 each independently include one or more of hydrogen, fluorine, chlorine, and trifluoromethyl.
  • the weight average molecular weight of the fluorine-containing polymer is 500,000 to 2.5 million, and can be optionally 1 million to 2 million.
  • Fluorine-containing polymers with a suitable weight-average molecular weight can improve the anti-rebound performance of the electrode while reducing the battery impedance, thereby improving the overall performance of the battery.
  • the molar content of the structural unit derived from the monomer represented by formula I is 15% to 40%, based on the total molar number of the structural units of the fluorine-containing polymer.
  • the molar content of the structural unit derived from the monomer represented by formula II is 40% to 60%, based on the total molar number of the structural units of the fluorine-containing polymer.
  • the molar content of the structural unit derived from the monomer represented by formula III is 10%-35%, based on the total molar number of the structural units of the fluorine-containing polymer.
  • Controlling the molar content of the structural units derived from the monomer represented by formula I, the monomer represented by formula II and the monomer represented by formula III within a suitable range can simultaneously improve the filterability of the negative electrode slurry, improve the anti-rebound performance of the negative electrode plate, reduce the internal resistance of the battery, and improve the electrochemical performance, processing efficiency and safety performance of the battery.
  • the monomer represented by formula I comprises one or more of vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene.
  • the monomer represented by formula II comprises one or more of B-hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, hydroxyethylhexyl acrylate, hydroxyethylhexyl methacrylate, and 5-hydroxypentyl-acrylate.
  • the monomer represented by formula III comprises at least one of acrylic acid, methacrylic acid, 2-ethylacrylic acid, 3-propylacrylic acid, trimethylacrylic acid, 2-isopropylacrylic acid, 2-methyl-3,3-diethylacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, and 2-methyl-2-hexenoic acid.
  • the second aspect of the present application provides a method for preparing a fluorine-containing polymer, comprising the following steps: polymerizing at least one monomer represented by formula I, at least one monomer represented by formula II, and at least one monomer represented by formula III under polymerizable conditions,
  • R1 , R2 , and R3 each independently include hydrogen, fluorine, chlorine, and C1-3 alkyl containing at least one fluorine atom;
  • R4 , R5 , R6 , R8 , R9 , and R10 each independently include hydrogen, substituted or unsubstituted C1-5 alkyl; and
  • R7 includes C1-10 alkyl containing at least one hydroxyl group.
  • R 1 in Formula I includes fluorine, and R 2 and R 3 each independently include one or more of hydrogen, fluorine, chlorine, and trifluoromethyl.
  • the molar content of the monomer represented by formula I is 15%-40%, based on the total molar number of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the molar content of the monomer represented by formula II is 40%-60%, based on the total molar number of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the molar content of the monomer represented by formula III is 10%-35%, based on the total molar number of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the polymerization reaction includes a first stage polymerization and a second stage polymerization
  • First stage polymerization adding an initiator, an emulsifier, at least one monomer represented by formula III and an aqueous medium into a reaction vessel 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 and at least one monomer represented by formula II are continuously introduced into the reaction container to carry out the second stage polymerization.
  • the fluorinated polymer prepared by the two-stage method has excellent dispersibility, and the chain segments formed by the polymerization of the monomers shown in formula II can effectively improve the flexibility and hydrophilicity of the chain segments formed by the polymerization of the monomers shown in formula I and formula III, thereby improving the dispersibility of the fluorinated polymer in an aqueous medium.
  • the mass percentage of the initiator provided in the first stage polymerization is 0.4%-0.8%, and the mass percentage of the initiator provided in the second stage polymerization is 0.1%-0.5%, based on the total mass of the monomers shown in formula I, the monomers shown in formula II and the monomers shown in formula III.
  • the mass percentage of the emulsifier is 0.01%-0.5%, based on the total mass of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the mass percentage of the aqueous medium provided in the first stage polymerization is 400%-600%, based on the total mass of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • reaction pressure of the first stage polymerization and the second stage polymerization are both 7MPa-9MPa, and the reaction temperature is both 80°C-100°C.
  • the emulsifier comprises an alkali metal perfluorooctanoate.
  • a third aspect of the present application provides an application of a fluorine-containing polymer in a secondary battery.
  • a fourth aspect of the present application provides a negative electrode slurry, comprising the fluorine-containing polymer of the first aspect or the fluorine-containing polymer prepared by the preparation method of the second aspect.
  • the negative electrode slurry provided in the present application has good dispersibility.
  • the fluorine-containing polymer is added to the negative electrode slurry in the form of an emulsion containing the fluorine-containing polymer.
  • the fluorine-containing polymer prepared by the preparation method in any of the above embodiments exists in the form of an emulsion and can be directly added to the negative electrode slurry for use, thereby reducing production costs and improving production efficiency.
  • the fifth aspect of the present application provides a negative electrode plate, including a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer includes a fluorine-containing polymer of any embodiment or a fluorine-containing polymer prepared by a preparation method of any embodiment.
  • the negative electrode plate provided in the present application has a low rebound rate, which is beneficial to improving the battery safety performance and cycle stability.
  • the mass content of the fluorinated polymer is 0.3% to 3.0%, based on The total mass of the negative electrode film layer.
  • a sixth aspect of the present application provides a secondary battery, comprising the negative electrode sheet of the fifth aspect.
  • the secondary battery includes at least one of a lithium secondary battery, a sodium secondary battery, a magnesium secondary battery, and a potassium secondary battery.
  • a seventh aspect of the present application provides an electrical device comprising the secondary battery of the sixth aspect.
  • FIG1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG2 is an exploded view of the secondary battery of one embodiment of the present application shown in FIG1 ;
  • FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG4 ;
  • FIG. 6 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 this application is defined in the form of a lower limit and an upper limit.
  • a given range is defined by selecting a lower limit and an upper limit.
  • the selected lower limit and upper limit define the boundaries of the particular range.
  • the range defined in this way can be inclusive or exclusive of the 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 the ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges of 60-110 and 80-120 are also expected.
  • the numerical range “ab” represents an abbreviation of any real number combination between a and b, where a and b are both real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" have been fully listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer 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.
  • 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 are open-ended or closed-ended.
  • the “include” and “comprising” may mean 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).
  • Negative electrode active materials usually include surface inert materials such as graphite and silicon. To improve the dispersion of active materials in the slurry and the uniformity of the electrode, it is usually necessary to add a certain amount of dispersant to the negative electrode slurry. However, the addition of a large amount of dispersant often leads to an increase in the rebound rate of the negative electrode and an increase in the battery impedance.
  • a fluorine-containing polymer which comprises a structural unit derived from a monomer represented by formula I, a structural unit derived from a monomer represented by formula II, and a structural unit derived from a monomer represented by formula III.
  • R1 , R2 , and R3 each independently include hydrogen, fluorine, chlorine, and C1-3 alkyl containing at least one fluorine atom;
  • R4 , R5 , R6 , R8 , R9 , and R10 each independently include hydrogen, substituted or unsubstituted C1-5 alkyl; and
  • R7 includes C1-10 alkyl containing at least one hydroxyl group.
  • 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 1-3 alkyl refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, with no unsaturation in the radical, having from one to three carbon atoms, and attached to the remainder of the molecule by a single bond.
  • Examples of C 1-3 alkyl include, but are not limited to: methyl, ethyl, n-propyl, isopropyl.
  • the C 1-3 alkyl group containing at least one fluorine atom refers to an alkyl group in which at least one hydrogen atom is substituted by a fluorine atom, and examples thereof include but are not limited to -CF 3 , -CH 2 CH 2 F, or -CHFCH 2 F.
  • C 1-10 alkyl can be understood with reference to the definition of the term “C 1-3 alkyl”.
  • Examples of C 1-10 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, n-nonyl, and n-decyl.
  • 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.
  • R 1 in Formula I is fluorine
  • R 2 and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and trifluoromethyl.
  • trifluoromethyl refers to a -CF3 group.
  • R7 in Formula II comprises a C4-10 alkyl group containing at least one hydroxyl group.
  • R7 in Formula II includes a long-chain group of at least 4 carbon atoms, which can further improve the flexibility of the fluorine-containing polymer, enhance the dispersion effect of the slurry, and reduce the impedance of the battery.
  • the monomer represented by Formula I comprises one or more of vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene.
  • the monomer represented by formula II comprises one or more of B-hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, hydroxyethylhexyl acrylate, hydroxyethylhexyl methacrylate, and 5-hydroxypentyl-acrylate.
  • the monomer represented by formula III comprises at least one of acrylic acid, methacrylic acid, 2-ethylacrylic acid, 3-propylacrylic acid, trimethylacrylic acid, 2-isopropylacrylic acid, 2-methyl-3,3-diethylacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, and 2-methyl-2-hexenoic acid.
  • the fluorinated polymer provided in the present application can act as both a binder and a dispersant; it can provide an effective binding effect on the negative electrode active material, and can effectively improve the filterability of the negative electrode slurry, reduce the added content of the dispersant in the negative electrode slurry, and thus effectively improve the negative electrode slurry.
  • the loading amount of the negative electrode active material and the reduction of the internal resistance of the battery can effectively ensure the bonding performance of the fluorinated polymer, and the structural unit derived from the monomer shown in formula II can effectively improve the dispersibility of the fluorinated polymer.
  • the carboxyl, ester and hydroxyl functional groups in the fluorinated polymer can act as anchor groups to easily interact with the oxygen-containing functional groups on the negative electrode active material to inhibit the agglomeration of the negative electrode active material.
  • the hydroxyl groups located on the side chain give the polymer a larger free volume, which can effectively improve the flexibility and dispersibility of the fluorinated polymer, thereby reducing the internal resistance of the battery.
  • the compaction density of the pole piece during the production process usually has a high design value.
  • the negative electrode active materials are mostly layered materials, which are prone to slippage. Therefore, the thickness of the pole piece tends to rebound after cold pressing.
  • the increase in the thickness of the pole piece causes the thickness of the battery cell to be higher than the design value, making it difficult to enter the shell; moreover, during the charge and discharge cycle, the expansion of the negative electrode active material will cause the pole piece to rebound further, increasing the expansion force on the battery cell, leaving a safety hazard.
  • the fluorinated polymer provided in this application can effectively suppress the rebound of the negative electrode pole piece while improving the slurry processing performance, thereby improving the battery manufacturing efficiency and safety of use.
  • the fluorine-containing polymer is an AB block polymer
  • the AB block polymer comprises an A block and a B block
  • the A block comprises a structural unit derived from a monomer represented by Formula I and a structural unit derived from a monomer represented by Formula III.
  • the B block comprises structural units derived from a monomer represented by Formula II.
  • the molar content of the structural unit derived from the monomer represented by Formula I is 15% to 40%, based on the total molar number of the structural units of the fluorine-containing polymer.
  • the molar content of the structural unit derived from the monomer represented by Formula I can be selected as 15%, 20%, 25%, 30%, 35%, 40% or any value therebetween, based on the total molar number of the structural units of the fluorine-containing polymer.
  • the molar content of the structural unit derived from the monomer represented by Formula III is 10% to 35%, based on the total molar number of the structural units of the fluorine-containing polymer.
  • the molar content of the structural unit derived from the monomer represented by Formula III can be 10%, 15%, 20%, 25%, 30% or any value therebetween, based on the fluorine-containing The total number of moles of the structural units of the polymer is calculated.
  • the molar content of the structural unit derived from the monomer represented by Formula II is 40% to 60%, based on the total molar number of the structural units of the fluorine-containing polymer.
  • the molar content of the structural unit derived from the monomer represented by Formula II can be 40%, 45%, 50%, 55%, 60% or any value therebetween, based on the total moles of the structural units of the fluorine-containing polymer.
  • Controlling the molar content of the structural units derived from the monomer represented by formula I, the monomer represented by formula II and the monomer represented by formula III within a suitable range can simultaneously improve the filterability of the negative electrode slurry, improve the anti-rebound performance of the negative electrode plate, reduce the internal resistance of the battery, and improve the electrochemical performance, processing efficiency and safety performance of the battery.
  • the weight average molecular weight of the fluorine-containing polymer is 500,000-2.5 million. In some embodiments, the weight average molecular weight of the fluorine-containing polymer can be 500,000, 750,000, 1 million, 1.25 million, 1.5 million, 1.75 million, 2 million, 2.25 million, 2.5 million, or any value therebetween.
  • 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 suitable weight-average molecular weight can improve the anti-rebound performance of the electrode while reducing the battery impedance, thereby improving the overall performance of the battery.
  • a method for preparing a fluorine-containing polymer comprises the following steps:
  • At least one monomer represented by formula I, at least one monomer represented by formula II and at least one monomer represented by formula III are polymerized,
  • R1 , R2 , and R3 each independently include hydrogen, fluorine, chlorine, and C1-3 alkyl containing at least one fluorine atom;
  • R4 , R5 , R6 , R8 , R9 , and R10 each independently include hydrogen, substituted or unsubstituted C1-5 alkyl; and
  • R7 includes C1-10 alkyl containing at least one hydroxyl group.
  • 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.
  • R 1 in Formula I is fluorine
  • R 2 and R 3 are each independently selected from one or more of hydrogen, fluorine, chlorine, and trifluoromethyl.
  • the molar content of the monomer represented by formula I is 15%-40%, based on the total moles of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the molar content of the monomer represented by formula II is 40%-60%, based on the total molar number of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the molar content of the monomer represented by formula III is 10%-35%, based on the total molar number of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the fluorinated polymer is an AB block polymer comprising A block and B block.
  • the polymerization reaction includes a first stage polymerization and a second stage polymerization.
  • the first stage polymerization is as follows: an initiator, an emulsifier, at least one monomer represented by formula III and an aqueous medium are added to a reaction container for first stage polymerization, and the monomer represented by formula I is continuously introduced into the first stage polymerization;
  • the second stage polymerization is as follows: after a period of reaction, an initiator and at least one monomer represented by formula II are continuously introduced into the reaction container for second stage polymerization.
  • the fluorine-containing polymer is an AB block polymer
  • the first stage polymerization generates an A block
  • the second stage polymerization generates a B block after the A block.
  • the fluorine-containing polymer prepared by the two-stage method has excellent dispersibility, and the chain segments formed by the polymerization of the monomer represented by formula II can effectively improve the flexibility and hydrophilicity of the chain segments formed by the polymerization of the monomers represented by formula I and formula III, thereby improving the dispersibility of the fluorine-containing polymer.
  • the mass percentage of the initiator provided in the first stage polymerization is 0.4%-0.8%, based on the total mass of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the mass percentage of the initiator provided in the first stage polymerization can be selected as 0.4%, 0.5%, 0.6%, 0.7%, 0.8% or any value therebetween, based on the total mass of the monomer represented by formula I, the monomer represented by formula II and the monomer represented by formula III.
  • the mass percentage of the initiator provided in the second stage polymerization is 0.1%-0.5%, based on the total mass of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the mass percentage of the initiator provided in the second stage polymerization can be selected as 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or any value therebetween, based on the total mass of the monomer represented by formula I, the monomer represented by formula II and the monomer represented by formula III.
  • the mass percentage of the emulsifier is 0.01%-0.5%, based on the total mass of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the mass percentage of the emulsifier can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or any value therebetween, based on the total mass of the monomer represented by formula I, the monomer represented by formula II and the monomer represented by formula III.
  • the mass percentage of the aqueous medium provided in the first stage polymerization is 400%-600%, based on the total mass of the monomer represented by formula I, the monomer represented by formula II, and the monomer represented by formula III.
  • the mass percentage of the aqueous medium provided in the first stage polymerization is 400%, 450%, 500%, 550%, 600% or any value therebetween, based on the total mass of the monomer represented by formula I, the monomer represented by formula II and the monomer represented by formula III.
  • reaction pressure of the first stage polymerization and the second stage polymerization are both 7MPa-9MPa, and the reaction temperature are both 80°C-100°C.
  • reaction pressure of the first stage polymerization and the second stage polymerization can be selected to be 7 MPa, 7.5 MPa, 8 MPa, 8.5 MPa, 9 MPa or any value therebetween.
  • the reaction temperature can be selected to be 80°C, 85°C, 90°C, 95°C, 100°C or any value therebetween.
  • the emulsifier comprises an alkali metal perfluorooctanoate.
  • the initiator comprises an amine initiator. In some embodiments, the initiator comprises N,N dimethylbenzylamine.
  • 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 fluorine-containing polymer is used as a binder in a secondary battery.
  • a negative electrode slurry comprising a fluorine-containing polymer according to any embodiment or a fluorine-containing polymer prepared by a preparation method according to any embodiment.
  • the fluorine-containing polymer is added to the negative electrode slurry in the form of an emulsion containing the fluorine-containing polymer.
  • binder refers to a chemical compound, polymer or mixture that functions as a binder and forms a colloidal solution or colloidal dispersion in a dispersion medium.
  • the fluorine-containing polymer prepared by the preparation method in any of the above embodiments exists in the form of an emulsion and can be directly added to the negative electrode slurry for use, thereby reducing production costs and improving production efficiency.
  • a negative electrode plate comprising a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a fluorine-containing polymer of any embodiment or a fluorine-containing polymer prepared by a preparation method of any embodiment.
  • the mass content of the fluorine-containing polymer is 0.3%-3%, based on the total mass of the negative electrode film layer.
  • the mass content of the fluorine-containing polymer may be 0.3%, 1%, 1.5%, 2%, 2.5%, 3% or any value therebetween, based on the total mass of the negative electrode film layer.
  • a secondary battery comprising the negative electrode sheet in any embodiment.
  • the secondary battery is 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, a positive electrode film layer and a water-based primer 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 and the aqueous primer layer are 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.
  • the metal foil aluminum foil may be used.
  • the composite current collector may include a polymer material-based
  • the composite current collector can 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 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 include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ) , and LiNi 0.8 Co 0.2 Mn 0.2 O 2 (also referred to as NCM 811 ,
  • 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 further 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 also optionally include a conductive agent.
  • the conductive agent may include superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, etc. At least one of tubes, graphene and carbon nanofibers.
  • the negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector.
  • 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.
  • a metal foil a 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 also optionally include other additives, such as thickeners.
  • additives such as thickeners.
  • Agents such as sodium carboxymethyl cellulose (CMC-Na)), etc.
  • the negative electrode sheet can be prepared by the following method: the fluorine-containing polymer, negative electrode active material, conductive agent and any other components in any embodiment are dispersed in a solvent (such as deionized water) to form a negative electrode slurry.
  • a solvent such as deionized water
  • the negative electrode slurry is coated on the current collector, and after drying, cold pressing and other processes, the 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, such as negative electrode film-forming additives, positive electrode film-forming additives, and 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.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and 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 glass fiber, non-woven fabric, At least one of ethylene, 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, which may 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.
  • FIG1 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 may be assembled into a battery module.
  • the number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG3 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 storage space, a plurality of secondary The battery 5 is accommodated in the accommodation 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.
  • FIG4 and FIG5 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 thereto.
  • a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • Fig. 6 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, etc.
  • 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;
  • the temperature in the kettle was raised to 90°C, and vinylidene fluoride was continuously introduced during the reaction to maintain the reaction pressure in the kettle constant;
  • the temperature in the reactor was maintained at 90°C and the pressure was maintained at 8.0 MPa; the reaction was continued for 10 hours;
  • the mixture was cooled to room temperature and filtered to obtain an emulsion containing a vinylidene fluoride-methacrylic acid-5-hydroxypentyl-acrylate copolymer.
  • the solid content of the above emulsion is adjusted to 25%; graphite, an emulsion containing a fluorine-containing polymer, sodium carboxymethyl cellulose and super P are mixed in an aqueous solvent to prepare a negative electrode slurry, wherein the mass content of graphite is 97.5%, the mass content of the fluorine-containing polymer is 1.5%, the mass content of super P is 0.7%, and the mass content of sodium carboxymethyl cellulose is 0.3%, based on the total mass of the slurry solid content.
  • the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil once or multiple times, and the negative electrode sheet is obtained after drying, cold pressing and slitting.
  • Lithium nickel cobalt manganese (NCM) material, conductive agent carbon black, polyvinylidene fluoride binder, and N-methylpyrrolidone (NMP) are stirred and mixed evenly in a weight ratio of 96.9:2.1:1:21 to obtain a positive electrode slurry with a solid content of 73%.
  • the positive electrode slurry is then evenly coated on a water-based primer current collector, and then dried, cold pressed, and cut to obtain a positive electrode sheet.
  • Polypropylene film is used as the isolation film.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrodes to play an isolating role, and then wound to obtain a bare cell, the tabs are welded to the bare cell, and the bare cell is placed in an aluminum shell and baked at 80°C to remove water, and then the electrolyte is injected and sealed to obtain an uncharged battery.
  • the uncharged battery then goes through the processes of static, hot and cold pressing, formation, shaping, capacity testing, etc. to obtain a battery product.
  • Example 2 the molar ratio of each monomer in the fluorine-containing polymer was adjusted, and other parameters remained the same as in Example 1.
  • the specific parameters are shown in Table 1.
  • Example 10 the polymerization temperature and the mass of the initiator for preparing the fluorine-containing polymer were adjusted so that the fluorine-containing polymer had different weight average molecular weights. Other parameters were kept consistent with those in Example 1. Specific parameters are shown in Table 1.
  • the weight average molecular weight of the fluorine-containing polymer in Example 10 is 1 million, and the specific preparation parameters are adjusted as follows: the reaction temperature is adjusted to 95° C., and the amount of N,N-dimethylbenzylamine added is adjusted to 56.7 g.
  • the weight average molecular weight of the fluorine-containing polymer in Example 11 is 2 million, and the specific preparation parameters are adjusted as follows: the reaction temperature is adjusted to 85° C., and the amount of N,N-dimethylbenzylamine added is adjusted to 51.3 g.
  • the weight average molecular weight of the fluorine-containing polymer in Example 12 is 500,000, and the specific preparation parameters are adjusted as follows: the reaction temperature is adjusted to 95° C., and the amount of N,N-dimethylbenzylamine added is adjusted to 59.4 g.
  • the weight average molecular weight of the fluorine-containing polymer in Example 13 is 2.5 million, and the specific preparation parameters are adjusted as follows: the reaction temperature is adjusted to 85° C., and the amount of N,N-dimethylbenzylamine added is adjusted to 48.6 g.
  • Example 14 to 17 the types of polymerization monomers were adjusted respectively, and other parameters remained consistent with those in Example 1. The specific parameters are shown in Table 1.
  • Example 18 the mass content of the binder in the negative electrode slurry was adjusted, and other parameters remained consistent with those in Example 1. The specific parameters are shown in Table 1.
  • Comparative Example 1 styrene-butadiene rubber with a weight average molecular weight of 80,000 is used as a binder, and other parameters are the same as those in Example 1. For specific parameters, see Table 1.
  • Comparative Example 2 styrene-butadiene rubber with a weight average molecular weight of 80,000 was used as a binder, the mass content of graphite in the negative electrode slurry was 96.5%, the mass content of fluorine-containing polymer was 1.5%, the mass content of super P was 0.7%, and the mass content of sodium carboxymethyl cellulose was 1.3%, based on the total mass of the slurry solid content.
  • Example 3 the comonomer does not include 5-hydroxypentyl acrylate, and the other preparation methods are consistent with those in Example 1.
  • Example 4 the comonomer does not include methacrylic acid, and other preparation methods are consistent with those in Example 1.
  • Example 5 the comonomer 5-hydroxypentyl-acrylate in Example 1 is replaced by methacrylate, and the other preparation methods are the same as those in Example 1.
  • 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 HT5 DMF 7.8 ⁇ 300 mm + 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
  • the filter is 150 mesh, and cut the filter into 25cm*25cm with scissors. Find a clean 500ml beaker and make sure the beaker is clean. Fold the 150 mesh filter into a triangle, take 500ml of slurry and pour it from the filter. Pour it all at once, and start recording the time when the slurry starts to flow from the tip of the filter into the beaker. Record the time for 300ml filtration. If the filtration time is within 10s, it is judged as Y, and if the filtration time is greater than 10s, it is judged as N.
  • the secondary battery was charged to 4.2V at a constant current rate of 1/3C, and then charged to a current of 0.05C at a constant voltage of 4.2V, and left for 5 minutes. Then, it was discharged at a rate of 1/3C for 90 minutes, the electrode assembly was adjusted to 50% SOC, and left for 60 minutes, and then discharged at a rate of 4C for 30S, and the 50% SOC discharge DCR was obtained according to the test data.
  • the coated negative electrode sheet was cold pressed to the designed compaction density (1.75g/cm 3 ), and the thickness of the negative electrode sheet was measured, which was recorded as h1; the cold pressed sheet was left to stand for 24 hours, and the thickness of the negative electrode sheet was measured, which was recorded as h2.
  • the rebound rate (%) of the sheet after cold pressing for 24 hours (h2-h1)/h1 ⁇ 100%.
  • the binders in the negative electrode slurries in Examples 1 to 21 are all fluorine-containing polymers disclosed in the present application, including (a) any one of the structural units derived from vinylidene fluoride and the structural units derived from chlorotrifluoroethylene; (b) any one of the structural units derived from methacrylic acid and the structural units derived from acrylic acid; (c) any one of the structural units derived from 5-hydroxypentyl-acrylate, the structural units derived from hydroxyethyl methacrylate and the structural units derived from hydroxyethyl acrylate.
  • the fluorine-containing polymer provided in the present application has good dispersibility, can reduce the amount of dispersant in the negative electrode slurry, effectively increase the loading amount of the active material, and reduce the internal resistance of the battery.
  • the fluorine-containing polymer provided in the present application can further suppress the rebound of the negative electrode sheet through the mutual cooperation between the polymer and the negative electrode active material on the basis of reducing the amount of dispersant, thereby improving the battery manufacturing efficiency and safety of use.
  • the weight average molecular weight of the fluorine-containing polymer is 500,000-2.5 million
  • the negative electrode slurry has good filterability
  • the pole piece has excellent anti-rebound performance
  • the battery has low impedance.
  • the weight average molecular weight of the fluorine-containing polymer is 1 million-2 million, the comprehensive performance of the battery is further optimized.

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Abstract

本申请提供一种含氟聚合物，其包含衍生自式I所示单体的结构单元、衍生自式II所示单体的结构单元和衍生自式III所示单体的结构单元，其中，R1、R2、R3各自独立地包括氢、氟、氯、至少含有一个氟原子的C1-3烷基，R4、R5、R6、R8、R9、R10各自独立地包括氢、取代或未取代的C1-5烷基，R7包括至少含有一个羟基的C1-10烷基。

Description

含氟聚合物、制备方法、负极浆料、负极极片、二次电池及用电装置
交叉引用
本申请引用于2023年5月29日递交的名称为“含氟聚合物、制备方法、负极浆料、负极极片、二次电池及用电装置”的第202310618024.2号中国专利申请，其通过引用被全部并入本申请。
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、制备方法、负极浆料、负极极片、二次电池及用电装置。
背景技术
近年来，随着二次电池的应用范围越来越广泛，二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。
极片是二次电池的重要组件，对二次电池的性能有关键影响。极片中通常加入粘结剂以粘结活性材料。粘结剂分子量大，在溶剂中分散性差，常常引发活性材料的团聚，导致电池性能的下降。
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，该含氟聚合物可以在提供一定粘结力的同时提高浆料的分散性，降低极片的反弹率和电池的直流阻抗。
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、衍生自式II所示单体的结构单元和衍生自式III所示单体的结构单元，
其中，R1、R2、R3各自独立地包括氢、氟、氯、至少含有一个氟原子的C1-3烷基，R4、R5、R6、R8、R9、R10各自独立地包括氢、取代或未取代的C1-5烷基，R7包括至少含有一个羟基的C1-10烷基。
本申请提供的含氟聚合物既能起到粘结剂，又能起到分散剂的作用；既能对负极活性材料提供有效的粘结作用，又能有效改善负极浆料的过滤性，减少分散剂在负极浆料中的添加含量，进而有效提高负极活性材料的负载量、降低电池内阻。其中，衍生自式I所示单体的结构单元能够有效保证含氟聚合物的粘结性能，衍生自式II所示单体的结构单元能够有效提高含氟聚合物的分散性，含氟聚合物中的羧基、酯基和羟基官能团能够作为锚固基团易于与负极活性材料上的含氧官能团发生作用，抑制负极活性材料的团聚。相比于主链上含有羟基的聚合物，位于侧链上的羟基使得聚合物链段更容易运动，能够有效提高含氟聚合物的柔性和分散能力，进而降低电池内阻。
为了提高电池的能量密度，生产过程中极片的压实密度通常具有高的设计值。但是负极活性材料多为层状材料，容易发生滑移，因此，极片在冷压后其厚度往往会发生反弹，极片厚度增加导致电芯厚度值高于设计值，难以入壳；而且，在充放电循环过程中，负极活性材料膨胀会引发极片的进一步反弹，使得电芯受到的膨胀力增加，留下安全隐患。申请人意外地发现本申请提供的含氟聚合物在提高浆料加工 性能的同时还能够有效抑制负极极片的反弹，提高电池制造效率和使用安全性。
在任意实施方式中，式I中的R1包括氟，R2、R3各自独立地包括氢、氟、氯、三氟甲基中的一种或多种。
在任意实施方式中，含氟聚合物的重均分子量为50万-250万，可选为100万-200万。
具有合适重均分子量的含氟聚合物能够在提高极片抗反弹性能的同时降低电池阻抗，提高电池的综合性能。
在任意实施方式中，衍生自式I所示单体的结构单元的摩尔含量为15％-40％，基于含氟聚合物的结构单元的总摩尔数计。
在任意实施方式中，衍生自式II所示单体的结构单元的摩尔含量为40％-60％，基于含氟聚合物的结构单元的总摩尔数计。
在任意实施方式中述衍生自式III所示单体的结构单元的摩尔含量为10％-35％，基于含氟聚合物的结构单元的总摩尔数计。
控制衍生自式I所示单体、式II所示单体和式III所示单体的结构单元的摩尔含量在合适的范围内可以同时改善负极浆料的过滤性，提高负极极片的抗反弹性能，降低电池内阻，提高电池的电化学性能、加工效率和安全性能。
在任意实施方式中，式Ⅰ所示单体包含氟乙烯、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，式II所示单体包含甲基丙烯酸-B-羟丙酯、丙烯酸羟乙酯、甲基丙烯酸羟乙酯、丙烯酸羟丙酯、丙烯酸羟丁酯、甲基丙烯酸羟丁酯、丙烯酸羟己酯、甲基丙烯酸羟己酯、丙烯酸羟乙基己基酯、甲基丙烯酸羟乙基己基酯、5-羟基戊基-丙烯酸酯中的一种或多种。
在任意实施方式中，式III所示单体包含丙烯酸、甲基丙烯酸、2‐乙基丙烯酸、3‐丙基丙烯酸、三甲基丙烯酸、2‐异丙基丙烯酸、2‐甲基‐3,3‐二乙基丙烯酸、3‐丁基丙烯酸、2‐丁基丙烯酸、2‐戊基丙烯酸、2‐甲基‐2‐己烯酸中的至少一种。
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、至少一种式II所示单体和至少一种式III所示单体进行聚合反应，
其中，R1、R2、R3各自独立地包括氢、氟、氯、至少含有一个氟原子的C1-3烷基，R4、R5、R6、R8、R9、R10各自独立地包括氢、取代或未取代的C1-5烷基，R7包括至少含有一个羟基的C1-10烷基。
在任意实施方式中，式I中的R1包括氟，R2、R3各自独立地包括氢、氟、氯、三氟甲基中的一种或多种。
在任意实施方式中，式I所示单体的摩尔含量为15％-40％，基于式I所示单体、式II所示单体、式III所示单体的总摩尔数计。
在任意实施方式中，式II所示单体的摩尔含量为40％-60％，基于式I所示单体、式II所示单体、式III所示单体的总摩尔数计。
在任意实施方式中，式III所示单体的摩尔含量为10％-35％，基于式I所示单体、式II所示单体、式III所示单体的总摩尔数计。
在任意实施方式中，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、乳化剂、至少一种式III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，向反应容器内连续送入引发剂、至少一种式II所示单体进行第二段聚合。
相比于通过将式I所示单体、式II所示单体和式III所示单体全部同时通入反应容器制备出的含氟聚合物，采用两段法制备的含氟聚 合物具有优异的分散性，式II所示单体聚合形成的链段能够有效改善式I和式III所示单体聚合形成的链段的柔性和亲水性，进而提高含氟聚合物在水性介质中的分散性。
在任意实施方式中，第一段聚合中提供的引发剂的质量百分比为0.4％-0.8％，第二段聚合中提供的引发剂的质量百分比为0.1％-0.5％，基于式I所示单体、式II所示单体和式III所示单体的总质量计。
在任意实施方式中，乳化剂的质量百分比为0.01％-0.5％，基于式I所示单体、式II所示单体、式III所示单体的总质量计。
在任意实施方式中，第一段聚合中提供的水性介质的质量百分比为400％-600％，基于式I所示单体、式II所示单体和式III所示单体的总质量计。
在任意实施方式中，第一段聚合和第二段聚合的反应压力均为7MPa-9MPa，反应温度均为80℃-100℃。
在任意实施方式中，乳化剂包含全氟辛酸碱金属盐。
本申请的第三方面提供一种含氟聚合物在二次电池中的应用。
本申请的第四方面提供一种负极浆料，包含第一方面的含氟聚合物或第二方面的制备方法制备的含氟聚合物。
本申请提供的负极浆料具有良好的分散性。
在任意实施方式中，含氟聚合物以包含含氟聚合物的乳液的形式加入负极浆料中。
利用上述任意实施方式中的制备方法制备的含氟聚合物，产物以乳液形式存在，可以直接加入到负极浆料中进行使用，降低了生产成本，提高了生产效率。
本申请的第五方面提供一种负极极片，包括负极集流体以及设置在负极集流体至少一个表面的负极膜层，负极膜层包括任意实施方式的含氟聚合物或任意实施方式的制备方法制备的含氟聚合物。
本申请提供的负极极片具有低的反弹率，有利于电池安全性能和循环稳定性的提高。
在任意实施方式中，含氟聚合物的质量含量为0.3％-3.0％，基于 负极膜层的总质量计。
本申请的第六方面提供一种二次电池，包括第五方面的负极极片。
在任意实施方式中，二次电池包括锂二次电池、钠二次电池、镁二次电池、钾二次电池中的至少一种。
本申请的第七方面提供一种用电装置，包括第六方面的二次电池。
附图说明
图1是本申请一实施方式的二次电池的示意图；
图2是图1所示的本申请一实施方式的二次电池的分解图；
图3是本申请一实施方式的电池模块的示意图；
图4是本申请一实施方式的电池包的示意图；
图5是图4所示的本申请一实施方式的电池包的分解图；
图6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：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53盖板。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的含氟聚合物、制备方法、负极浆料、负极极片、二次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)。
负极活性材料通常包括石墨、硅等表面惰性材料。为了提高负极 活性材料在浆料中的分散性、改善极片的均匀性，通常需要在负极浆料中加入一定量的分散剂。然而分散剂的大量加入往往会导致负极极片的反弹率增加、电池阻抗增大。
[含氟聚合物]
基于此，本申请提供一种含氟聚合物，该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和衍生自式III所示单体的结构单元，
其中，R1、R2、R3各自独立地包括氢、氟、氯、至少含有一个氟原子的C1-3烷基，R4、R5、R6、R8、R9、R10各自独立地包括氢、取代或未取代的C1-5烷基，R7包括至少含有一个羟基的C1-10烷基。
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“C1-3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，具有从一至三个碳原子，并且通过单键附接到分子的其余部分。C1-3烷基的示例包括但不限于：甲基、乙基、正丙基、异丙基。
在一些实施方式中，至少含有一个氟原子的C1-3烷基是指至少一个氢原子被氟原子取代的烷基，作为示例，其包括但不限于-CF3、-CH2CH2F或-CHFCH2F。
在本文中，术语“C1-10烷基”可以参照术语“C1-3烷基”的定义来理解。C1-10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、正癸基。
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、C1-6烷基、C1-6烷氧基。
在一些实施方式中，式I中的R1为氟，R2、R3各自独立地选自氢、氟、氯、三氟甲基中的一种或多种。
在本文中，术语“三氟甲基”是指-CF3基团。
在一些实施方式中，式II中的R7包含至少含有一个羟基的C4-10烷基。
式II中的R7包括至少4个碳原子的长链基团，能够进一步改善含氟聚合物柔性、提升浆料分散效果，降低电池的阻抗。
在一些实施方式中，式Ⅰ所示单体包含氟乙烯、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所示单体包含甲基丙烯酸-B-羟丙酯、丙烯酸羟乙酯、甲基丙烯酸羟乙酯、丙烯酸羟丙酯、丙烯酸羟丁酯、甲基丙烯酸羟丁酯、丙烯酸羟己酯、甲基丙烯酸羟己酯、丙烯酸羟乙基己基酯、甲基丙烯酸羟乙基己基酯、5-羟基戊基-丙烯酸酯中的一种或多种。
在一些实施方式中，式III所示单体包含丙烯酸、甲基丙烯酸、2‐乙基丙烯酸、3‐丙基丙烯酸、三甲基丙烯酸、2‐异丙基丙烯酸、2‐甲基‐3,3‐二乙基丙烯酸、3‐丁基丙烯酸、2‐丁基丙烯酸、2‐戊基丙烯酸、2‐甲基‐2‐己烯酸中的至少一种。
本申请提供的含氟聚合物既能起到粘结剂，又能起到分散剂的作用；既能对负极活性材料提供有效的粘结作用，又能有效改善负极浆料的过滤性，减少分散剂在负极浆料中的添加含量，进而有效提高负 极活性材料的负载量、降低电池内阻。其中，衍生自式I所示单体的结构单元能够有效保证含氟聚合物的粘结性能，衍生自式II所示单体的结构单元能够有效提高含氟聚合物的分散性，含氟聚合物中的羧基、酯基和羟基官能团能够作为锚固基团易于与负极活性材料上的含氧官能团发生作用，抑制负极活性材料的团聚。相比于主链上含有羟基的聚合物，位于侧链上的羟基使得聚合物具有更大的自由体积，能够有效提高含氟聚合物的柔性和分散能力，进而降低电池内阻。
为了提高电池的能量密度，生产过程中极片的压实密度通常具有高的设计值。但是负极活性材料多为层状材料，容易发生滑移，因此，极片在冷压后其厚度往往会发生反弹，极片厚度增加导致电芯厚度值高于设计值，难以入壳；而且，在充放电循环过程中，负极活性材料膨胀会引发极片的进一步反弹，使得电芯受到的膨胀力增加，留下安全隐患。申请人意外地发现本申请提供的含氟聚合物在提高浆料加工性能的同时还能够有效抑制负极极片的反弹，提高电池制造效率和使用安全性。
在一些实施方式中，含氟聚合物为AB嵌段聚合物，AB嵌段聚合物包含A嵌段和B嵌段，A嵌段包含衍生自式I所示单体的结构单元和衍生自式III所示单体的结构单元。
在一些实施方式中，B嵌段包含衍生自式II所示单体的结构单元。
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为15％-40％，基于含氟聚合物的结构单元的总摩尔数计。
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为15％、20％、25％、30％、35％、40％或其间的任意数值，基于含氟聚合物的结构单元的总摩尔数计。
在一些实施方式中，衍生自式III所示单体的结构单元的摩尔含量为10％-35％，基于含氟聚合物的结构单元的总摩尔数计。
在一些实施方式中，衍生自式III所示单体的结构单元的摩尔含量可选为10％、15％、20％、25％、30％或其间的任意数值，基于含氟 聚合物的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为40％-60％，基于含氟聚合物的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40％、45％、50％、55％、60％或其间的任意数值，基于含氟聚合物的结构单元的总摩尔数计。
控制衍生自式I所示单体、式II所示单体和式III所示单体的结构单元的摩尔含量在合适的范围内可以同时改善负极浆料的过滤性，提高负极极片的抗反弹性能，降低电池内阻，提高电池的电化学性能、加工效率和安全性能。
在一些实施方式中，含氟聚合物的重均分子量为50万-250万。在一些实施方式中，含氟聚合物的重均分子量可选为50万、75万、100万、125万、150万、175万、200万、225万、250万或其间的任意数值。
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。
具有合适重均分子量的含氟聚合物能够在提高极片抗反弹性能的同时降低电池阻抗，提高电池的综合性能。
本申请的一个实施方式中，提供了一种含氟聚合物的制备方法， 所述制备方法包括以下步骤：
将至少一种式I所示单体、至少一种式II所示单体和至少一种式III所示单体进行聚合反应，
其中，R1、R2、R3各自独立地包括氢、氟、氯、至少含有一个氟原子的C1-3烷基，R4、R5、R6、R8、R9、R10各自独立地包括氢、取代或未取代的C1-5烷基，R7包括至少含有一个羟基的C1-10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。
在一些实施方式中，式I中的R1为氟，R2、R3各自独立地选自氢、氟、氯、三氟甲基中的一种或多种。
在一些实施方式中，所述式I所示单体的摩尔含量为15％-40％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总摩尔数计。
在一些实施方式中，所述式II所示单体的摩尔含量为40％-60％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总摩尔数计。
在一些实施方式中，所述式III所示单体的摩尔含量为10％-35％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总摩尔数计。
在一些实施方式中，所述含氟聚合物为AB嵌段聚合物，包括A 嵌段和B嵌段。
在一些实施方式中，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、乳化剂、至少一种式III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，向反应容器内连续送入引发剂、至少一种式II所示单体进行第二段聚合。
在一些实施方式中，含氟聚合物为AB嵌段聚合物，第一段聚合生成A嵌段，第二段聚合在A嵌段后生成B嵌段。
相比于通过将式I所示单体、式II所示单体和式III所示单体全部同时通入反应容器制备出的含氟聚合物，采用两段法制备的含氟聚合物具有优异的分散性，式II所示单体聚合形成的链段能够有效改善式I和式III所示单体聚合形成的链段的柔性和亲水性，进而提高含氟聚合物的分散性。
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0.4％-0.8％，基于所述式I所示单体、所述式II所示单体和所述式III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引发剂的质量百分比可选为0.4％、0.5％、0.6％、0.7％、0.8％或其间的任意数值，基于所述式I所示单体、所述式II所示单体和所述式III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0.1％-0.5％，基于所述式I所示单体、所述式II所示单体和所述式III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可选为0.1％、0.2％、0.3％、0.4％、0.5％或其间的任意数值，基于所述式I所示单体、所述式II所示单体和所述式III所示单体的总质量计。
在一些实施方式中，乳化剂的质量百分比为0.01％-0.5％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总质量计。
在一些实施方式中，乳化剂的质量百分比可选为0.01％、0.1％、 0.2％、0.3％、0.4％、0.5％或其间的任意数值，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总质量计。
在一些实施方式中，所述第一段聚合中提供的水性介质的质量百分比为400％-600％，基于所述式I所示单体、所述式II所示单体和所述式III所示单体的总质量计。
在一些实施方式中，所述第一段聚合中提供的水性介质的质量百分比为400％、450％、500％、550％、600％或其间的任意数值，基于所述式I所示单体、所述式II所示单体和所述式III所示单体的总质量计。
在一些实施方式中，所述第一段聚合和所述第二段聚合的反应压力均为7MPa-9MPa，反应温度均为80℃-100℃。
在一些实施方式中，所述第一段聚合和所述第二段聚合的反应压力可选为7MPa、7.5MPa、8MPa、8.5MPa、9MPa或其间的任意数值。
在一些实施方式中，反应温度可选为80℃、85℃、90℃、95℃、100℃或其间的任意数值。
在一些实施方式中，乳化剂包含全氟辛酸碱金属盐。
在一些实施方式中，引发剂包含胺类引发剂。在一些实施方式中，引发剂包含N，N二甲基苄胺。
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。
[负极浆料]
本申请的一个实施方式中提供一种负极浆料，包含任意实施方式的含氟聚合物或任意实施方式的制备方法制备的含氟聚合物。
在一些实施方式中，含氟聚合物以包含所述含氟聚合物的乳液的形式加入所述负极浆料中。
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起到粘结作用的化学化合物、聚合物或混合物。
利用上述任意实施方式中的制备方法制备的含氟聚合物，产物以乳液形式存在，可以直接加入到负极浆料中进行使用，降低了生产成本，提高了生产效率。
[负极极片]
本申请的一个实施方式中提供一种负极极片，包括负极集流体以及设置在所述负极集流体至少一个表面的负极膜层，所述负极膜层包括任意实施方式的含氟聚合物或任意实施方式的制备方法制备的含氟聚合物。
在一些实施方式中，所述含氟聚合物的质量含量为0.3％-3％，基于所述负极膜层的总质量计。
在一些实施方式中，所述含氟聚合物的质量含量可选为0.3％、1％、1.5％、2％、2.5％、3％或其间的任意数值，基于所述负极膜层的总质量计。
本申请的一个实施方式中，提供一种二次电池，包括任意实施方式中的负极极片。
在一些实施方式中，二次电池为锂离子电池、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和水性底涂层。
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，正极膜层和水性底涂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，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LiCoO2)、锂镍氧化物(如LiNiO2)、锂锰氧化物(如LiMnO2、LiMn2O4)、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LiNi1/3Co1/3Mn1/3O2(也可以简称为NCM333)、LiNi0.5Co0.2Mn0.3O2(也可以简称为NCM523)、LiNi0.5Co0.25Mn0.25O2(也可以简称为NCM211)、LiNi0.6Co0.2Mn0.2O2(也可以简称为NCM622)、LiNi0.8Co0.1Mn0.1O2(也可以简称为NCM811)、锂镍钴铝氧化物(如LiNi0.85Co0.15Al0.05O2)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LiFePO4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO4)、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。
[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负极膜层。
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，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：将任意实施方式中的含氟聚合物、负极活性材料、导电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，电解质采用电解液。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，电解质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1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2，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3是作为一个示例的电池模块4。参照图3，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4和图5是作为一个示例的电池包1。参照图4和图5，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6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30000g的去离子水(电导率小于等于2μs/cm)、15g的全氟辛酸钠盐、1730.3g甲基丙烯酸、43.2g的N，N二甲基苄胺依次加入反应釜内，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至釜内压力为8.0MPa；
釜内升温至90℃，反应过程中不断通入偏氟乙烯维持釜内反应压力不变；
718.3g偏氟乙烯单体全部通入后，继续反应6小时；
将10.8g的N，N二甲基苄胺和3551.3g的5-羟基戊基-丙烯酸酯匀速加入反应釜内，关闭反应釜；
维持釜内温度为90℃，压力8.0MPa；继续反应10h；
反应完成时釜内压力降至0.5MPa；
冷却至室温，过滤出料，得到包含偏二氟乙烯-甲基丙烯酸-5-羟基戊基-丙烯酸酯共聚物的乳液。
2)负极极片的制备
将上述乳液的固含量调整为25％；将石墨、包含含氟聚合物的乳液、羧甲基纤维素钠和super P在水溶剂中混合，制备负极浆料，其中石墨的质量含量为97.5％，含氟聚合物的质量含量为1.5％，super P的质量含量为0.7％，羧甲基纤维素钠的质量含量为0.3％，基于浆料固含量的总质量计。将负极浆料一次或多次均匀涂覆在负极集流体铜箔上，经过烘干、冷压、分切得到负极极片。
3)正极极片的制备
将锂镍钴锰(NCM)材料、导电剂碳黑、聚偏二氟乙烯粘结剂、N-甲基吡咯烷酮(NMP)按重量比为96.9:2.1:1:21搅拌混合均匀，得到正极浆料，浆料的固含量为73％；之后将正极浆料均匀涂覆于水性底涂集流体上，之后经过烘干、冷压、分切，得到正极极片。
4)电解液的制备
在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)，将有机溶剂碳酸乙烯酯(EC)/碳酸甲乙酯(EMC)按照体积比3/7混合均匀，加入12.5％LiPF6锂盐溶解于有机溶剂中，搅拌均匀，得到电解液。
5)隔离膜
以聚丙烯膜作为隔离膜。
6)电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到裸电芯，给裸电芯焊接极耳，并将裸电芯装入铝壳中，并在80℃下烘烤除水，随即注入电解液并封口，得到不带电的电池。不带电的电池再依次经过静置、热冷压、化成、整形、容量测试等工序，获得电池产品。
实施例2～实施例9中调节含氟聚合物中各单体的摩尔配比，其他参数同实施例1保持一致，具体参数见表1。
实施例10～实施例13中调整制备含氟聚合物的聚合温度和引发剂的质量，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。
实施例10中的含氟聚合物重均分子量为100万，具体制备参数调整为：反应温度调整为95℃，N,N二甲基苄胺添加量调整为56.7g。
实施例11中的含氟聚合物重均分子量为200万，具体制备参数调整为：反应温度调整为85℃，N,N二甲基苄胺添加量调整为51.3g。
实施例12中的含氟聚合物重均分子量为50万，具体制备参数调整为：反应温度调整为95℃，N,N二甲基苄胺添加量调整为59.4g。
实施例13中的含氟聚合物重均分子量为250万，具体制备参数调整为：反应温度调整为85℃，N,N二甲基苄胺添加量调整为48.6g。
实施例14～实施例17中分别调整了聚合单体的种类，其他参数同实施例1保持一致，具体参数见表1。
实施例18～实施例21中调整了负极浆料中粘结剂的质量含量，其他参数同实施例1保持一致，具体参数见表1。
对比例1中，以重均分子量为8万的丁苯橡胶作为粘结剂，其他参数同实施例1，具体参数参见表1。
对比例2中，以重均分子量为8万的丁苯橡胶作为粘结剂，负极浆料中石墨的质量含量为96.5％，含氟聚合物的质量含量为1.5％，super P的质量含量为0.7％，羧甲基纤维素钠的质量含量为1.3％，基于浆料固含量的总质量计。
对比例3中，共聚单体不包括5-羟基戊基-丙烯酸酯，其他制备方法与实施例1一致。
对比例4中，共聚单体不包括甲基丙烯酸，其他制备方法与实施例1一致。
对比例5中，将实施例1中的共聚单体5-羟基戊基-丙烯酸酯替换为甲基丙烯酸酯，其他制备方法同实施例1一致。
二、测试方法
1、含氟聚合物的重均分子量的测量
采用Waters2695Isocratic 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：StyragelHT5DMF7.8×300mm+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、负极浆料的过滤性能测试
先确定过滤网150目，将过滤网用剪刀剪成25cm*25cm。找一干净的500ml烧杯，确定烧杯干净。将150目过滤网折成三角形，取浆料500ml从过滤网上面倒入，一下子全部倒完，从滤网尖端开始往烧杯中流浆料时，开始记录时间。记录300ml过滤的时间,过滤时间在10s以内判定为Y，过滤时间大于10s判定为N。
3、极片性能测试
(1)直流阻抗测试
在25℃下，将二次的电池以1/3C的倍率恒流充电至4.2V，再以4.2V恒定电压充电至电流为0.05C，搁置5min后。然后以1/3C的倍率放电90min，调节电极组件为50％SOC，静置60min，然后以4C的倍率放电30S，根据测试数据得到50％SOC放电DCR。
(2)极片冷压24小时后的极片反弹率测试
将涂布好的负极极片冷压到设计的压实密度(1.75g/cm3)，测试负极极片厚度，记为h1；将冷压后的极片静置24小时后，测试负极极片的厚度，记为h2。极片冷压24小时后反弹率(％)＝(h2‐h1)/h1×100％。
三、测试结果
上述实施例和对比例的测试结果见表1。
表1
根据表1结果可知，实施例1～21中的负极浆料中的粘结剂均为本申请公开的含氟聚合物，包含(a)衍生自偏二氟乙烯的结构单元、衍生自三氟氯乙烯的结构单元中的任意一种；(b)衍生自甲基丙烯酸的结构单元、衍生自丙烯酸的结构单元中的任意一种；(c)衍生自5-羟基戊基-丙烯酸酯的结构单元、衍生自甲基丙烯酸羟乙酯、衍生自丙烯酸羟乙酯的结构单元中的任意一种。
从对比例1、2可见，现有技术中通常需要在负极浆料中加入1.5％质量含量的分散剂羧甲基纤维素钠才能实现负极浆料的有效分散，但是分散剂的加入会导致负极极片的反弹率增加、电池阻抗增大。从实施例1-21可见，本申请提供的含氟聚合物具有良好的分散性，能够减少分散剂在负极浆料中的用量，有效提高活性材料的负载量、降低电池内阻。而且本申请提供的含氟聚合物能够在降低分散剂用量的基础上，通过聚合物与负极活性材料之间的相互配合进一步抑制负极极片的反弹，提高电池制造效率和使用安全性。
从实施例1～9可见，基于所述含氟聚合物的结构单元的总摩尔数计，衍生自偏二氟乙烯的结构单元的摩尔含量为15％-40％、衍生自5-羟基戊基-丙烯酸酯的结构单元的摩尔含量为40％-60％，衍生自甲基丙烯酸的结构单元的摩尔含量为10％-35％时，含氟聚合物能够有效改善负极浆料的过滤性，提高负极极片的抗反弹性能，降低电池内阻，提高电池的电化学性能、加工效率和安全性能。
从实施例10～13可见，含氟聚合物的重均分子量为50万-250万，负极浆料具有良好的过滤性，极片具有优异的抗反弹性，电池具有低的阻抗。含氟聚合物的重均分子量为100万-200万时，电池的综合性能进一步优化。
从实施例18～21可见，基于所述负极膜层的总质量计，所述含氟聚合物的质量含量为0.3％-3.0％时，负极浆料具有良好的过滤性，极片具有优异的抗反弹性，电池具有低的阻抗。含氟聚合物的质量含量为1％-2％时，电池的综合性能进一步优化。
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 (28)

  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、衍生自式II所示单体的结构单元和衍生自式III所示单体的结构单元，
    其中，R1、R2、R3各自独立地包括氢、氟、氯、至少含有一个氟原子的C1-3烷基，R4、R5、R6、R8、R9、R10各自独立地包括氢、取代或未取代的C1-5烷基，R7包括至少含有一个羟基的C1-10烷基。
  2. 根据权利要求1所述的含氟聚合物，其特征在于，所述式I中的R1包括氟，R2、R3各自独立地包括氢、氟、氯、三氟甲基中的一种或多种。
  3. 根据权利要求1或2所述的含氟聚合物，其特征在于，所述含氟聚合物的重均分子量为50万-250万，可选为100万-200万。
  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，所述衍生自式I所示单体的结构单元的摩尔含量为15％-40％，基于所述含氟聚合物的结构单元的总摩尔数计。
  5. 根据权利要求1至4中任一项所述的含氟聚合物，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40％-60％，基于所述含氟聚合物的结构单元的总摩尔数计。
  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，所述衍生自式III所示单体的结构单元的摩尔含量为10％-35％，基于所述含氟聚合物的结构单元的总摩尔数计。
  7. 根据权利要求1至6中任一项所述的含氟聚合物，其特征在于，所述式Ⅰ所示单体包含氟乙烯、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。
  8. 根据权利要求1至7中任一项所述的含氟聚合物，其特征在于，所述式II所示单体包含甲基丙烯酸-B-羟丙酯、丙烯酸羟乙酯、甲基丙烯酸羟乙酯、丙烯酸羟丙酯、丙烯酸羟丁酯、甲基丙烯酸羟丁酯、丙烯酸羟己酯、甲基丙烯酸羟己酯、丙烯酸羟乙基己基酯、甲基丙烯酸羟乙基己基酯、5-羟基戊基-丙烯酸酯中的一种或多种。
  9. 根据权利要求1至8中任一项所述的含氟聚合物，其特征在于，所述式III所示单体包含丙烯酸、甲基丙烯酸、2‐乙基丙烯酸、3‐丙基丙烯酸、三甲基丙烯酸、2‐异丙基丙烯酸、2‐甲基‐3,3‐二乙基丙烯酸、3‐丁基丙烯酸、2‐丁基丙烯酸、2‐戊基丙烯酸、2‐甲基‐2‐己烯酸中的至少一种。
  10. 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、至少一种式II所示单体和至少一种式III所示单体进行聚合反应，

    其中，R1、R2、R3各自独立地包括氢、氟、氯、至少含有一个氟原子的C1-3烷基，R4、R5、R6、R8、R9、R10各自独立地包括氢、取代或未取代的C1-5烷基，R7包括至少含有一个羟基的C1-10烷基。
  11. 根据权利要求10所述的制备方法，其特征在于，所述式I中的R1包括氟，R2、R3各自独立地包括氢、氟、氯、三氟甲基中的一种或多种。
  12. 根据权利要求10或11所述的制备方法，其特征在于，所述式I所示单体的摩尔含量为15％-40％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总摩尔数计。
  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，所述式II所示单体的摩尔含量为40％-60％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总摩尔数计。
  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，所述式III所示单体的摩尔含量为10％-35％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总摩尔数计。
  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、乳化剂、至少一种式III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，向反应容器内连续送入引发剂、 至少一种式II所示单体进行第二段聚合。
  16. 根据权利要求15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的质量百分比为0.4％-0.8％，所述第二段聚合中提供的引发剂的质量百分比为0.1％-0.5％，基于所述式I所示单体、所述式II所示单体和所述式III所示单体的总质量计。
  17. 根据权利要求15或16所述的制备方法，其特征在于，所述乳化剂的质量百分比为0.01％-0.5％，基于所述式I所示单体、所述式II所示单体、所述式III所示单体的总质量计。
  18. 根据权利要求15至17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400％-600％，基于所述式I所示单体、所述式II所示单体和所述式III所示单体的总质量计。
  19. 根据权利要求15至18中任一项所述的制备方法，其特征在于，所述第一段聚合和所述第二段聚合的反应压力均为7MPa-9MPa，反应温度均为80℃-100℃。
  20. 根据权利要求15至19中任一项所述的制备方法，其特征在于，所述乳化剂包含全氟辛酸碱金属盐。
  21. 权利要求1至9中任一项所述的含氟聚合物或权利要求10至20中任一项所述的制备方法制备的含氟聚合物在二次电池中的应用。
  22. 一种负极浆料，包含权利要求1至9中任一项所述的含氟聚合物或权利要求10至20中任一项所述的制备方法制备的含氟聚合 物。
  23. 根据权利要求22所述的负极浆料，其特征在于，所述含氟聚合物以包含所述含氟聚合物的乳液的形式加入所述负极浆料中。
  24. 一种负极极片，包括负极集流体以及设置在所述负极集流体至少一个表面的负极膜层，所述负极膜层包括权利要求1至9中任一项所述的含氟聚合物或权利要求10至20中任一项所述的制备方法制备的含氟聚合物。
  25. 根据权利要求24所述的负极极片，其特征在于，所述含氟聚合物的质量含量为0.3％-3.0％，可选为1％-2％，基于所述负极膜层的总质量计。
  26. 一种二次电池，其特征在于，包括权利要求24或25所述的负极极片。
  27. 根据权利要求26所述的二次电池，其特征在于，所述二次电池包括锂二次电池、钠二次电池、镁二次电池、钾二次电池中的至少一种。
  28. 一种用电装置，其特征在于，包括权利要求26或27所述的二次电池。
PCT/CN2023/136775 2023-05-29 2023-12-06 含氟聚合物、制备方法、负极浆料、负极极片、二次电池及用电装置 Ceased WO2024244366A1 (zh)

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