WO2023230895A1 - 粘结剂组合物、二次电池、电池模块、电池包及用电装置 - Google Patents

粘结剂组合物、二次电池、电池模块、电池包及用电装置 Download PDF

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WO2023230895A1
WO2023230895A1 PCT/CN2022/096409 CN2022096409W WO2023230895A1 WO 2023230895 A1 WO2023230895 A1 WO 2023230895A1 CN 2022096409 W CN2022096409 W CN 2022096409W WO 2023230895 A1 WO2023230895 A1 WO 2023230895A1
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Prior art keywords
copolymer
battery
group
acrylate
lithium
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PCT/CN2022/096409
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English (en)
French (fr)
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段连威
刘会会
李�诚
冯伟
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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 KR1020237028193A priority Critical patent/KR20230168179A/ko
Priority to EP22927580.5A priority patent/EP4310944A4/en
Priority to CN202280041711.6A priority patent/CN117501470A/zh
Priority to PCT/CN2022/096409 priority patent/WO2023230895A1/zh
Priority to JP2023550047A priority patent/JP2024526405A/ja
Priority to US18/515,290 priority patent/US20240124699A1/en
Publication of WO2023230895A1 publication Critical patent/WO2023230895A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • C08F220/42—Nitriles
    • C08F220/44—Acrylonitrile
    • 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
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
    • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
    • C08F220/1802—C2-(meth)acrylate, e.g. ethyl (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
    • 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
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
    • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
    • C08F220/1804—C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or 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; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or 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; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/12—Compositions of homopolymers or 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; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08L27/16—Homopolymers or copolymers or vinylidene fluoride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or 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 of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C08L33/08—Homopolymers or copolymers of acrylic acid esters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or 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 of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/18—Homopolymers or copolymers of nitriles
    • C08L33/20—Homopolymers or copolymers of acrylonitrile
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, and in particular to a binder composition, secondary batteries, battery modules, battery packs and electrical devices.
  • lithium-ion batteries have been widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. With the popularity of lithium-ion battery applications, higher requirements have been placed on its performance and cost.
  • Binders are commonly used materials in lithium-ion batteries and are in great demand for battery pole pieces, separators, packaging, etc.
  • the existing binders are high in cost and have poor adhesion, which increases the cost of the battery and reduces the cycle performance of the battery. Therefore, existing adhesives still need to be improved.
  • This application was made in view of the above-mentioned problems, and its object is to provide an adhesive composition which can reduce adhesive costs and has excellent adhesive performance.
  • a first aspect of the application provides a binder composition comprising a fluoropolymer A and a copolymer B comprising structural units derived from a monomer containing a cyano group and derived from an ester containing The structural unit of the monomer of the base group.
  • the present application uses fluoropolymer A and copolymer B including structural units derived from monomers containing cyano groups and structural units derived from monomers containing ester groups as a binder. , compared with using fluoropolymer A or copolymer B alone as a binder, the bonding performance of the binder and the cycle performance of the battery can be further improved.
  • the weight average molecular weight of fluoropolymer A is 600,000-900,000, and the weight average molecular weight of copolymer B is 400,000-700,000.
  • Controlling the weight average molecular weight of the polymer can balance the adhesiveness and processability of the binder.
  • the weight average molecular weight of the polymer is too low and the brittleness is too high, resulting in insufficient adhesive force of the binder.
  • the weight average molecular weight of the polymer is too high, making it difficult to disperse the electrode active material.
  • a reasonable combination of polymers with different molecular weights can improve the dispersion of electrode active materials, thereby improving battery performance.
  • the mass ratio of fluoropolymer A to copolymer B is 1:4-4:1.
  • the reasonable combination of fluoropolymer A and copolymer B within a certain quality range can further improve the bonding performance of the binder and the cycle performance of the battery.
  • the fluoropolymer A is selected from one or more of polyvinylidene fluoride, its copolymer with tetrafluoroethylene, hexafluoropropylene, and trichlorethylene.
  • the monomer containing a cyano group is selected from one or more of acrylonitrile, methacrylonitrile, halogenated acrylonitrile, and methoxyacrylonitrile.
  • the monomer containing an ester group is selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isopentyl acrylate, isooctyl acrylate, methyl methacrylate, methyl One or more of ethyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
  • the above-mentioned monomers containing cyano groups and monomers containing ester groups are low-cost, are not subject to policy restrictions, can be mass-produced, and can significantly reduce the cost of binders.
  • the mass ratio of structural units derived from monomers containing cyano groups to structural units derived from monomers containing ester groups in copolymer B is 8:1 to 12:1.
  • Monomers containing cyano groups can improve the mechanical strength and bonding properties of copolymer B, and can further improve the cycle performance of the battery.
  • a small amount of monomers containing ester groups can improve the flexibility of copolymer B and avoid the occurrence of pole pieces. brittle fracture, and the ester group has a certain ability to absorb electrolyte and retain liquid, which can improve the problem of poor ionic conductivity of fluoropolymer A.
  • copolymer B further comprises structural units derived from monomers containing groups represented by Formula I,
  • n is selected from 0, 1, 2 or 3.
  • the electronegativity of the oxygen element in the group shown in formula I is greater than that of the nitrogen element in the cyano group. Compared with the cyano group in copolymer B, it is easier for the electrode active material and the conductive agent to form hydrogen bonds and the bond energy is Stronger, it can greatly improve the dispersion of the slurry, making the solid matter in the slurry less likely to precipitate, and increasing the solid content of the slurry. At the same time, the addition of the group shown in Formula I can further improve the adhesion of the battery pole pieces and the cycle resistance of the battery.
  • the monomer containing the group represented by Formula I is selected from one or more of N-vinylpyrrolidone and N-allyl-2-pyrrolidone.
  • the above-mentioned monomers have low cost, good stability, and are easy to process and synthesize.
  • the mass content of structural units derived from monomers containing groups represented by Formula I is 0.1% to 2%, based on the total mass of copolymer B. Containing an appropriate amount of groups represented by formula I in copolymer B can improve the dispersion performance of copolymer B, making the prepared slurry less likely to precipitate, helping to increase the solid content of the slurry, thereby increasing the loading capacity of the electrode.
  • the third aspect of this application provides a secondary battery, including an electrode assembly and an electrolyte.
  • the electrode assembly includes a positive electrode piece, a separator, and a negative electrode piece.
  • the positive electrode piece includes a positive active material and the first or second aspect of this application. of adhesive.
  • the battery has better cycle performance.
  • the positive active material is a lithium-containing transition metal oxide, which may be lithium iron phosphate, or their doped modified materials, or their conductive carbon coating modified materials, conductive metal coating modified materials, etc. At least one of the modified materials is coated with a conductive material or a conductive polymer.
  • a fourth aspect of the present application provides a battery module, including the secondary battery of the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack, including the battery module of the fourth aspect of the present application.
  • a sixth aspect of the present application provides an electrical device, including at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, and the battery pack of the fifth aspect of the present application.
  • the battery module of the fourth aspect and the battery pack of the fifth aspect of the present application include the secondary battery of the third aspect, and therefore have the same advantages as the secondary battery.
  • Figure 1 is a bonding performance test chart of the adhesive prepared in Example 1 and Comparative Example 1;
  • Figure 2 is a cycle test curve of the battery prepared in Example 1 and Comparative Example 1;
  • FIG. 3 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 4 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 3 .
  • FIG. 5 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 6 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 7 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 6 .
  • FIG. 8 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • PVDF is a commonly used battery binder, but its cost is high and its bonding force is poor. During the battery cycle, the bonding force weakens, which will further lead to a decrease in the cycle performance of the battery. Based on the above technical problems, this application develops a low-cost adhesive that simultaneously provides the pole pieces with excellent adhesive force, significantly improving the cycle performance of the battery.
  • a binder composition which includes fluoropolymer A and copolymer B.
  • Copolymer B includes structural units derived from monomers containing cyano groups and derived from ester groups. The structural unit of a group of monomers.
  • binder composition refers to a mixture of chemical compounds or polymers that form a colloidal solution or colloidal dispersion in a dispersion medium, such as water.
  • the dispersion medium of the binder is an aqueous solvent, such as water.
  • the dispersion medium of the adhesive is an oily solvent.
  • oily solvent include but are not limited to dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, acetone, dicarbonate Methyl ester, ethyl cellulose, polycarbonate.
  • adhesives are used to hold electrode materials and/or conductive agents in place and adhere them to conductive metal components to form electrodes.
  • the electrode does not contain any conductive agent.
  • the binder serves as a positive electrode binder and is used to bind the positive electrode active material and/or the conductive agent to form the positive electrode.
  • the binder serves as a negative electrode binder and is used to bind the negative electrode active material and/or the conductive agent to form the negative electrode.
  • polymer includes on the one hand an assembly of chemically homogeneous macromolecules prepared by polymerization reactions (copolymerization, homopolymerization), but differing in degree of polymerization, molar mass and chain length.
  • the term on the other hand also includes derivatives of aggregates of macromolecules formed by polymerization reactions which are obtainable by reaction, for example addition or substitution, of functional groups in said macromolecules and which may be chemically homogeneous or chemically A non-homogeneous compound or mixture.
  • fluoropolymer refers to a polymer containing fluorine element.
  • copolymer refers to a polymer prepared by polymerizing two or more different types of monomers.
  • cyano refers to the -CN group.
  • ester group refers to a group with the general formula -COOR 9 structural unit, R 9 is selected from a C 1-5 alkyl group substituted or unsubstituted by a substituent, examples of ester groups include but are not limited to : Methyl ester, ethyl ester, propyl ester, butyl ester, amyl ester, isooctyl ester, etc.
  • substituted means substituted by a substituent, each of which is independently selected from: hydroxyl, mercapto, amino, cyano, nitro, aldehyde, halogen atom, C 1-6 alkyl, C 1-6 alkoxy.
  • copolymer B is selected from the group consisting of acrylonitrile-methyl acrylate copolymer, acrylonitrile-2-methyl methacrylate copolymer, acrylonitrile-2-ethyl methacrylate copolymer, acrylonitrile-acrylic acid Ethyl ester copolymer, acrylonitrile-butyl acrylate copolymer, acrylonitrile-isoctyl acrylate copolymer, acrylonitrile-butyl acrylate-hydroxyethyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer , acrylonitrile-isoamyl acrylate-hydroxypropyl acrylate copolymer, acrylonitrile-butyl acrylate-isooctyl acrylate-methyl methacrylate copolymer, acrylonitrile-butyl acrylate-iso
  • Structural units derived from monomers containing cyano groups can not only effectively complex with the surface metal of the current collector, but also with the metal elements on the electrode active material, ensuring a strong bond between the electrode active material and the current collector. force.
  • structural units derived from monomers containing ester groups can improve the flexibility of the pole piece and avoid brittle fracture of the pole piece.
  • the cyano group and ester group on copolymer B and the fluorine element in fluoropolymer A create stronger adhesion between the electrode active material particles on the pole piece through hydrogen bonding.
  • fluoropolymer A and copolymer B containing structural units derived from monomers containing cyano groups and structural units derived from monomers containing ester groups are used as binders together.
  • fluoropolymer A or copolymer B alone as a binder, the bonding properties between the electrode active material and the current collector, the electrode active material and the conductive agent, the electrode active material and/or the conductive agent and the current collector are significantly improved.
  • the bonding performance significantly improves the cycle performance of the battery.
  • fluoropolymer A has a weight average molecular weight of 6 ⁇ 10 5 -9 ⁇ 10 5 and copolymer B has a weight average molecular weight of 4 ⁇ 10 5 -7 ⁇ 10 5 .
  • the weight average molecular weight of fluoropolymer A is selected from 6 ⁇ 10 5 -8 ⁇ 10 5 , or 6 ⁇ 10 5 -7 ⁇ 10 5 , or 7 ⁇ 10 5 -9 ⁇ 10 5 , or 8 ⁇ 10 5 -9 ⁇ 10 5 .
  • the weight average molecular weight of copolymer B is selected from 4 ⁇ 10 5 -7 ⁇ 10 5 , or 4 ⁇ 10 5 -6 ⁇ 10 5 , or 4 ⁇ 10 5 -5 ⁇ 10 5 , or 5 ⁇ 10 5 -7 ⁇ 10 5 , or 6 ⁇ 10 5 -7 ⁇ 10 5 .
  • weight average molecular weight refers to the sum of the weight fractions of molecules of different molecular weights in the polymer multiplied by their corresponding molecular weights.
  • Controlling the weight average molecular weight of the polymer can balance the adhesiveness and processability of the binder.
  • the weight average molecular weight of the polymer is too low and the brittleness is too high, resulting in insufficient adhesive force of the binder.
  • the weight average molecular weight of the polymer is too high, making it difficult to disperse the electrode active material.
  • a reasonable combination of polymers with different molecular weights can improve the dispersion of electrode active materials, thereby improving battery performance.
  • the mass ratio of fluoropolymer A to copolymer B is 1:4-4:1. In some embodiments, the mass ratio of fluoropolymer A to copolymer B is 1:4-3:1, or 1:4-2:1, or 1:4-1:1, or 1:2- 1:4, or 1:2-4:1, or 1:1-4:1, or 2:1-4:1, or 3:1-4:1.
  • the reasonable combination of fluoropolymer A and copolymer B within a certain mass range can further improve the adhesion of the electrode piece and the cycle performance of the battery.
  • the fluoropolymer A is selected from one or more of polyvinylidene fluoride, its copolymer with tetrafluoroethylene, hexafluoropropylene, and trichlorethylene.
  • the fluoropolymer A is polyvinylidene fluoride, which is synthesized by an emulsion method, has a particle volume average particle size Dv50 of 5-10 ⁇ m, a crystallinity of 35-40%, and a melting point of 160-170°C.
  • polyvinylidene fluoride synthesized by the emulsion method has a larger single synthesis capacity and lower cost.
  • the appropriate molecular weight enables the slurry containing the binder of the present application to have both excellent suspension and dispersion properties, preventing the binder from settling or agglomerating, resulting in uneven dispersion of the binder in the slurry.
  • Appropriate particle size can effectively reduce the dissolution time of polyvinylidene fluoride and thus reduce the time of slurry preparation.
  • the appropriate crystallinity of polyvinylidene fluoride can ensure good adhesion without causing the brittleness problem of the pole piece.
  • the higher melting point prevents polyvinylidene fluoride from melting and deactivating when the coating dries.
  • the monomer containing a cyano group is selected from one or more of acrylonitrile, methacrylonitrile, halogenated acrylonitrile, and methoxyacrylonitrile.
  • the monomer containing an ester group is selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isopentyl acrylate, isooctyl acrylate, methyl methacrylate, methyl acrylate One or more of ethyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
  • the monomer containing an ester group is selected from isooctyl acrylate.
  • Isooctyl acrylate makes copolymer B have a lower glass transition temperature and better flexibility, which is beneficial to the processing and manufacturing of pole pieces.
  • the above-mentioned monomers containing cyano groups and monomers containing ester groups are low-cost, are not subject to policy restrictions, can be mass-produced, and can significantly reduce the cost of binders.
  • the mass ratio of structural units derived from monomers containing cyano groups to structural units derived from monomers containing ester groups in copolymer B is 8:1 to 12:1. In some embodiments, the mass ratio of structural units derived from monomers containing cyano groups to structural units derived from monomers containing ester groups in copolymer B is 8:1 to 11:1, or 8:1 ⁇ 10:1, or 8:1 ⁇ 9:1, or 9:1 ⁇ 12:1, or 10:1 ⁇ 12:1, or 11:1 ⁇ 12:1.
  • Monomers containing cyano groups can improve the mechanical strength and bonding properties of copolymer B, and can further improve the cycle performance of the battery.
  • a small amount of monomers containing ester groups can improve the flexibility of copolymer B and avoid the occurrence of pole pieces. Brittle fracture, and the ester group has a certain ability to absorb electrolyte and retain liquid, which can improve the problem of poor ionic conductivity of fluoropolymer A and improve the ionic conductivity of the binder.
  • copolymer B further comprises structural units derived from monomers containing groups represented by Formula I,
  • n is selected from 0, 1, 2 or 3.
  • the electronegativity of the oxygen element in the group shown in formula I is greater than that of the nitrogen element in the cyano group. Compared with the cyano group in copolymer B, it is easier to form hydrogen bonds with the electrode active material and conductive agent and the bond energy is Stronger, it can greatly improve the dispersion of slurry and increase the solid content of slurry. At the same time, the addition of the group shown in formula I can further improve the adhesive force of the binder and the cycle performance of the battery.
  • the monomer containing the group represented by Formula I is selected from one or more of N-vinylpyrrolidone and N-allyl-2-pyrrolidone.
  • the above-mentioned monomers have low cost, good stability, and are easy to process and synthesize.
  • the mass content of structural units derived from monomers containing groups represented by Formula I is 0.1% to 2%, based on the total mass of copolymer B. In some embodiments, the mass content of structural units derived from monomers containing groups represented by Formula I is 0.5% to 2%, or 0.5% to 1.5%, based on the total mass of copolymer B. Containing an appropriate amount of groups represented by formula I in copolymer B can improve the dispersion performance of copolymer B, making the prepared slurry less likely to precipitate, helping to increase the solid content of the slurry, thereby increasing the loading capacity of the electrode.
  • a second aspect of the present application provides a binder, which includes copolymer C.
  • Copolymer C includes structural units derived from monomers containing cyano groups, structural units derived from monomers containing ester groups. , and structural units derived from monomers containing groups represented by formula I,
  • n is selected from 0, 1, 2 or 3.
  • the electronegativity of the oxygen element in the group shown in formula I is greater than that of the nitrogen element in the cyano group. Compared with the cyano group in the copolymer, it is easier for the electrode active material and the conductive agent to form hydrogen bonds and the bond energy is higher. Strong, it can greatly improve the dispersion of slurry and increase the solid content of slurry.
  • Monomers containing cyano groups can effectively complex with metals on current collectors and electrode active materials to ensure strong adhesion between electrode active materials and current collectors.
  • Monomers containing ester groups can improve the brittleness of the pole piece and avoid brittle fracture of the pole piece.
  • the present application adopts the method of including structural units derived from monomers containing cyano groups, structural units derived from monomers containing ester groups, and monomers derived from monomers containing groups represented by formula I.
  • the copolymer C of the structural unit serves as a binder, which reduces the cost of the binder without reducing the solid content of the slurry, and improves the bonding performance of the binder and the cycle performance of the battery.
  • the monomer containing a cyano group is selected from one or more of acrylonitrile, methacrylonitrile, halogenated acrylonitrile, and methoxyacrylonitrile.
  • the mass content of structural units derived from monomers containing cyano groups is 80% to 95%, based on the total mass of copolymer C. In some embodiments, the mass content of structural units derived from monomers containing cyano groups is 81% to 95%, or 82% to 95%, or 83% to 95%, or 84% to 84%. 95%, or 85% to 95%, or 86% to 95%, or 87% to 95%, or 88% to 95%, or 88% to 94%, or 88% to 93% , or 88% to 92%, or 88% to 91%, based on the total mass of copolymer C. Within this range, copolymer C can further improve the bonding performance of the binder and the cycle performance of the battery.
  • the monomer containing an ester group is selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isopentyl acrylate, isooctyl acrylate, methyl methacrylate, methyl One or more of ethyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
  • the monomer containing an ester group is selected from isooctyl acrylate.
  • Isooctyl acrylate makes copolymer C have a lower glass transition temperature and better flexibility, which is beneficial to the processing and manufacturing of pole pieces.
  • the above-mentioned monomers containing cyano groups and monomers containing ester groups are low-cost, are not subject to policy restrictions, can be mass-produced, and can significantly reduce the cost of binders.
  • the mass content of structural units derived from monomers containing ester groups is 8% to 12%, based on the total mass of copolymer C. In some embodiments, the mass content of structural units derived from monomers containing ester groups is 8% to 11%, or 9% to 11%, based on the total mass of copolymer C. Within this range, copolymer C can further improve the bonding performance of the binder and the cycle performance of the battery.
  • the mass ratio of structural units derived from monomers containing cyano groups to structural units derived from monomers containing ester groups in copolymer C is 8:1 to 12:1.
  • Monomers containing cyano groups can improve the mechanical strength and bonding properties of copolymer B, and can further improve the cycle performance of the battery.
  • a small amount of monomers containing ester groups can improve the flexibility of copolymer B and avoid the occurrence of pole pieces. brittle fracture, and the ester group has a certain ability to absorb electrolyte and retain liquid, which can improve the problem of poor ionic conductivity of fluoropolymer A.
  • copolymer C can further improve the electrode piece adhesion and battery cycle performance.
  • the monomer containing the group represented by Formula I is selected from one or more of N-vinylpyrrolidone and N-allyl-2-pyrrolidone.
  • the mass content of structural units derived from monomers containing groups represented by Formula I is 0.1% to 2%, or 0.5% to 1.5%, based on the total mass of copolymer C. Containing an appropriate amount of groups represented by formula I in copolymer B can improve the dispersion performance of copolymer B, so that the prepared slurry contains more electrode active materials, which helps to increase the solid content of the slurry.
  • copolymer C has a weight average molecular weight of 4 ⁇ 10 5 to 7 ⁇ 10 5 . In some embodiments, the weight average molecular weight of copolymer C is selected from 4 ⁇ 10 5 -7 ⁇ 10 5 , or 4 ⁇ 10 5 -6 ⁇ 10 5 , or 4 ⁇ 10 5 -5 ⁇ 10 5 , or 5 ⁇ 10 5 -7 ⁇ 10 5 , or 6 ⁇ 10 5 -7 ⁇ 10 5 .
  • Controlling the weight average molecular weight of copolymer C can take into account both the adhesiveness and processability of the binder.
  • the weight average molecular weight of copolymer C is too low and too brittle, resulting in insufficient adhesive force of the binder.
  • the weight average molecular weight of copolymer C is too high, making it difficult to disperse the electrode active material.
  • the reasonable combination of copolymers with different molecular weights can improve the dispersion of electrode active materials, thereby improving battery performance.
  • the volume average particle size Dv50 of copolymer C is 5-20 ⁇ m.
  • Dv50 refers to the particle size at which the cumulative particle size distribution percentage of the particles reaches 50%. Its physical meaning is that 50% of the particles are larger than it, and 50% are smaller than it. Dv50 is also called the median diameter or median diameter.
  • the average particle size Dv50 of copolymer C is too large, it will cause dissolution difficulties.
  • the poor dispersion of the slurry will cause the conductive agent or electrode active material and the binder to form agglomerates and block the filter screen, affecting production.
  • the agglomerates will be washed into the coating head and produce Scratches on coating particles affect coating quality.
  • the appropriate average particle size Dv50 helps to increase the dissolution speed of copolymer C in the solvent and improve the processing efficiency of the pole piece.
  • Copolymer C has an intrinsic viscosity of 0.8-1.1 dl/g.
  • intrinsic viscosity refers to the most common expression of the viscosity of a polymer solution. It is defined as the reduced viscosity when the concentration of the polymer solution approaches zero. That is to say, it represents the contribution of a single molecule to the viscosity of the solution. It is a viscosity that reflects the characteristics of the polymer, and its value does not change with concentration.
  • the intrinsic viscosity of the present invention refers to the intrinsic viscosity measured in N,N-dimethylacetamide at 30°C.
  • Controlling the intrinsic viscosity of copolymer C within an appropriate range can enable copolymer C to have both excellent bonding properties and processing properties. Avoid the inability to achieve effective bonding due to too low viscosity, and avoid difficulties in stirring, preparing and coating the slurry due to too high viscosity.
  • a third aspect of the application provides a method for preparing an adhesive, which includes the following steps:
  • n is selected from 0, 1, 2 or 3;
  • Copolymer C is prepared by polymerizing a monomer containing a cyano group, a monomer containing an ester group, and a monomer containing a group represented by Formula I under polymerizable conditions.
  • copolymer C is copolymerized by conventional emulsion polymerization using an anionic emulsifier.
  • preparing copolymer C by polymerizing a monomer containing a cyano group, a monomer containing an ester group, and a monomer containing a group represented by Formula I under polymerizable conditions includes a polymerization pressure
  • a first amount of pH buffer and a first amount of initiator are used to perform the first stage reaction at the first polymerization temperature; and after the first stage reaction, a second amount of a monomer containing a cyano group is added to the system, A monomer containing an ester group, and a monomer containing a group represented by Formula I are mixed with a second amount of a reaction solvent, a second amount of an emulsifier, a second amount of a pH buffer, and a second amount of an initiator
  • the emulsifier is selected from one or more alkali metal salts or alkyl salts of perfluorooctanoic acid.
  • the alkali metal salt of perfluorooctanoic acid is selected from one or more types of sodium perfluorooctanoate and potassium perfluorooctanoate.
  • the alkyl acid salt is selected from one or more types of alkyl sulfate and alkyl sulfonate.
  • the initiator is selected from peroxides
  • the peroxides are selected from one or more of persulfate inorganic peroxides and peroxide carbonates
  • the inorganic peroxide is selected from ammonium persulfate.
  • one or more potassium persulfates, and the peroxide carbonates are selected from diisopropyl peroxydicarbonate.
  • the reaction solvent is deionized water.
  • the pH buffering agent is selected from one or more of ammonia, potassium carbonate, and potassium bicarbonate.
  • the first amount of the monomer containing a cyano group, the monomer containing an ester group, and the monomer containing the group shown in Formula I is 75-90% of the amount of each monomer formula
  • the first amount of reaction solvent is 70-80% of the total amount of monomers added in the first stage reaction
  • the first amount of emulsifier is 0.2-0.3% of the total amount of monomers added in the first stage reaction
  • the first amount of The pH buffering agent is 0.05-0.2% of the total amount of monomers added in the first stage reaction
  • the first amount of initiator is 0.15-1% of the total amount of monomers added in the first stage reaction.
  • the first polymerization temperature is 70-80°C, and the reaction time of the first stage reaction is 2-3 hours.
  • the second amount of the monomer containing the cyano group, the monomer containing the ester group, and the monomer containing the group shown in Formula I is 10-25% of the amount of each monomer formula
  • the second amount of reaction solvent is 20-30% of the total amount of monomers added in the second stage reaction.
  • the second amount of emulsifier is 0.05-0.1% of the total amount of monomers added in the second stage reaction.
  • the initiator is 0.05-0.3% of the total amount of monomers added in the second stage reaction, the second polymerization temperature is 85-90°C, and the reaction time of the second stage reaction is 3-4 hours.
  • the mass ratio of the monomer containing a cyano group to the monomer containing an ester group is 8:1 to 12:1, and the mass ratio of the monomer containing the group shown in Formula I The content is 0.1% to 2%, based on the total mass of copolymer C.
  • the monomer containing a cyano group is selected from one or more of acrylonitrile, methacrylonitrile, halogenated acrylonitrile, methoxyacrylonitrile; and/or contains an ester group
  • the monomer is selected from methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isopentyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl acrylate
  • One or more of propyl ester; and/or the monomer containing the group shown in formula I is selected from one or more of N-vinylpyrrolidone and N-propenylpyrrolidone.
  • This method has low monomer preparation cost, mild reaction conditions, and can reduce the cost of the binder.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector has two surfaces facing each other in its own 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.
  • the metal foil aluminum foil can 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 base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for batteries.
  • the cathode 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 of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (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 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon.
  • At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include 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 above-mentioned components for preparing the positive electrode sheet, such as the positive active material, the conductive agent, the binder of the present application and any other components are dispersed in a solvent (such as N-methylpyrrolidone), a positive electrode slurry is formed; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own 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 composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative 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, and the like.
  • 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 battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes other binders.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polysodium acrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a conductive agent.
  • the conductive agent 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 optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is an electrolyte solution.
  • the electrolyte solution includes electrolyte salts and solvents.
  • the electrolyte salt may be selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluoroborate, lithium dioxaloborate, lithium difluorodioxalate phosphate and lithium tetrafluoroxalate phosphate.
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • 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 film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • This application provides a secondary battery, including an electrode assembly and an electrolyte.
  • the electrode assembly includes a positive electrode piece, a separator film, and a negative electrode piece.
  • the positive electrode piece includes a positive electrode active material and a binder in any embodiment of the application or the present invention.
  • the adhesive prepared by the preparation method of any embodiment is applied.
  • the secondary battery has better cycle performance.
  • the positive active material is a lithium-containing transition metal oxide, which may be lithium iron phosphate, or their doped modified materials, or their conductive carbon coating modified materials, conductive metal coating modified materials, etc. At least one of the modified materials is coated with a conductive material or a conductive polymer.
  • the lithium-containing transition metal oxide may be lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminate, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, manganese phosphate Lithium iron, lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel type lithium manganate, spinel type lithium nickel manganate, lithium titanate, or their doped modifications or at least one of their conductive carbon-coated modified materials, conductive metal-coated modified materials, or conductive polymer-coated modified materials.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • a secondary battery typically includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 3 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the fourth aspect of the present application provides an electrode, including an electrode active material and a binder composition or binder in any embodiment.
  • the electrode active material can be a cathode active material, and the cathode active material is Lithium-containing transition metal oxides.
  • the lithium-containing transition metal oxide may be lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminate, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, manganese phosphate Lithium iron, lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel type lithium manganate, spinel type lithium nickel manganate, lithium titanate, or their doped modifications or at least one of their conductive carbon-coated modified materials, conductive metal-coated modified materials, or conductive polymer-coated modified materials.
  • the lithium-containing transition metal oxide may be lithium iron phosphate, or their do
  • the electrode has higher adhesion, allowing the battery to have better cycle performance.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 5 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 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • a sixth aspect of the present application provides an electrical device, including a secondary battery in any embodiment, a battery module in any embodiment, or a battery pack in any embodiment.
  • the battery life of this electrical device is longer.
  • the secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device.
  • the electric 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, and 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 can be selected according to its usage requirements.
  • Figure 8 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • the preparation method of copolymer C is as follows: the polymerization kettle is a 10L stainless steel autoclave with a rotation speed of 100 r/min. First check the tightness of the polymerization system, then vacuum the autoclave and fill it with nitrogen to remove oxygen. Repeat three times. Add 2000g deionized water, 1.6g ammonia, 3.2g sodium alkyl sulfate, then add 1408g acrylonitrile monomer, 176g isooctyl acrylate monomer, 16g N-vinylpyrrolidone monomer, and evacuate to a polymerization pressure of 4.2Mpa.
  • N-vinylpyrrolidone-acrylonitrile-isooctyl acrylate is obtained. copolymer.
  • the weight average molecular weight of the prepared copolymer is 700,000, the particle size Dv50 is 15 ⁇ m, and the intrinsic viscosity is 1.1 dl/g.
  • the preparation method of the binder is as follows: 4g of polyvinylidene fluoride (fluoropolymer A) and 4g of N-vinylpyrrolidone-acrylonitrile-isooctyl acrylate copolymer are added to 250g of N-methylpyrrolidone solution. Stir on the stirring and dispersing machine at 500r/min for 90 minutes. After stirring, defoam on the ultrasonic cleaning machine for 30 minutes.
  • polyvinylidene fluoride is the 601A product produced by Dongyangguang Company. It is synthesized by the emulsion method. The weight average molecular weight is 900,000, the particle size Dv50 is 20 ⁇ m, the crystallinity is 40%, and the melting point is 170°C.
  • the above slurry is scraped onto the carbon-coated aluminum foil, baked at 110°C for 15 minutes, cold-pressed and cut into discs with a diameter of 15mm, and then combined with metal lithium sheets, isolation films, and electrolytes to make button batteries.
  • the batteries of Examples 2 to 25 and the button battery of Comparative Example 1 are similar to the button battery of Example 1, but the raw materials and proportions of the preparation of copolymer C or the proportions of each component in the binder are adjusted. , see Table 1 for specific parameters.
  • Example 2 the mass ratio of polyvinylidene fluoride and copolymer C was adjusted, and other parameters were consistent with Example 1. The specific parameters are shown in Table 1.
  • Example 8 to 11 the monomer polymerization ratio of acrylonitrile and isooctyl acrylate in the N-vinylpyrrolidone-acrylonitrile-isooctyl acrylate copolymer is adjusted, and other parameters are consistent with Example 1. The specific parameters are shown in Table 1 .
  • Example 12 to 13 the monomer polymerization ratio of acrylonitrile and isooctyl acrylate in the N-vinylpyrrolidone-acrylonitrile-isooctyl acrylate copolymer is adjusted, and polyvinylidene fluoride and N-vinylpyrrolidone-acrylonitrile are set -The mass ratio of the isooctyl acrylate copolymer is 2:1, and other parameters are consistent with Example 1. The specific parameters are shown in Table 1.
  • Example 14-15 the monomer polymerization ratio of acrylonitrile and isooctyl acrylate in the N-vinylpyrrolidone-acrylonitrile-isooctyl acrylate copolymer is adjusted, and polyvinylidene fluoride and N-vinylpyrrolidone-acrylonitrile are set -The mass ratio of isooctyl acrylate copolymer is 3:1, and other parameters are consistent with Example 1. The specific parameters are shown in Table 1.
  • Example 16-17 the monomer polymerization ratio of acrylonitrile and isooctyl acrylate in the N-vinylpyrrolidone-acrylonitrile-isooctyl acrylate copolymer is adjusted, and polyvinylidene fluoride and N-vinylpyrrolidone-acrylonitrile are set -The mass ratio of isooctyl acrylate copolymer is 4:1, and other parameters are consistent with Example 1. The specific parameters are shown in Table 1.
  • Example 18 to 20 the mass of N-vinylpyrrolidone added to polymer B was adjusted, and the molar ratio of acrylonitrile and isooctyl acrylate monomers in the N-vinylpyrrolidone-acrylonitrile-isooctyl acrylate copolymer was set. The ratio is 10:1, and other parameters are consistent with Example 1. See Table 1 for specific parameters.
  • Example 23 N-allyl-2-pyrrolidone modified acrylonitrile-isooctyl acrylate copolymer was used, and other parameters were consistent with Example 1. The specific parameters are shown in Table 1.
  • Example 24 N-vinylpyrrolidone is not added during the preparation of the copolymer, and the molar ratio of acrylonitrile and isooctyl acrylate monomers in the acrylonitrile-isooctyl acrylate copolymer is set to 10:1, and other parameters are as follows: Embodiment 1 remains the same, and the specific parameters are shown in Table 1.
  • Example 25 the polyvinylidene fluoride is the 401A product produced by Dongguang Sunshine Company, whose weight average molecular weight is 600,000. The other steps are consistent with Example 1. The specific parameters are shown in Table 1.
  • Comparative Example 1 polyvinylidene fluoride alone was used as the binder; in Comparative Example 2, the N-vinylpyrrolidone-modified acrylonitrile-isooctyl acrylate copolymer prepared in Example 9 was used as the binder. , in Comparative Example 3, the single acrylonitrile-isooctyl acrylate copolymer prepared in Example 24 was used as the binder. The other steps were the same as in Example 1. The specific parameters are shown in Table 1.
  • Example 1 the battery capacity retention rate test process is as follows: at 25°C, charge the battery corresponding to Example 1 with a constant current of 1/3C to 3.65V, and then charge with a constant voltage of 3.65V until the current is 0.05 C, leave it for 5 minutes, and then discharge it to 2.5V at 1/3C. The resulting capacity is recorded as the initial capacity C0. Repeat the above steps for the same battery, and at the same time record the discharge capacity Cn of the battery after the nth cycle.
  • the battery capacity retention rate data corresponding to Example 1 in Table 1 is the data measured after 500 cycles under the above test conditions, that is, the value of P500.
  • the testing procedures of Comparative Example 1 and other examples are the same as above.
  • Solid content test method Prepare a glass petri dish and record the weight m 1 , take a part of the prepared cathode slurry and put it into the glass petri dish and record the total weight m 2 , put the petri dish containing the cathode slurry into the drying box Medium heating, heating temperature 120°C, heating time 1h. Weigh the dried Petri dish and record the weight m 3 .
  • the solid content (m 3 -m 1 )/(m 2 -m 1 )*100%.
  • Examples 1 to 25 all provide a binder composition that includes polyvinylidene fluoride and acrylonitrile that includes structural units derived from acrylonitrile and structural units derived from isooctyl acrylate. -Isooctyl acrylate copolymer. Compared with Comparative Examples 1 to 3, they all achieved good results and improved the bonding performance of the binder and the battery capacity retention rate.
  • the weight average molecular weight of the polyvinylidene fluoride in Examples 1 to 25 is 600,000 to 900,000, and the weight average molecular weight of the acrylonitrile-isooctyl acrylate copolymer is 400,000 to 700,000. Compared with Comparative Examples 1 to 3, they all achieved good results and improved the bonding performance of the binder and the battery capacity retention rate.
  • Example 1 the mass ratio of polyvinylidene fluoride and acrylonitrile-isooctyl acrylate copolymer in the adhesive composition is 1:4 to 4:1. Compared with Comparative Examples 1 to 3, they all achieved good results and improved the bonding performance of the binder and the battery capacity retention rate.
  • the mass ratio of the structural units derived from acrylonitrile to the structural units derived from isooctyl acrylate in the acrylonitrile-isooctyl acrylate copolymers in Examples 1 to 25 is 8:1 to 12:1, and all of them have achieved Good effect, improving the adhesive performance and battery capacity retention rate of the binder.
  • the mass ratio of the structural units derived from acrylonitrile to the structural units derived from isooctyl acrylate in the acrylonitrile-isooctyl acrylate copolymer is When the ratio is 8:1 to 10:1, the adhesive performance and battery capacity retention rate of the binder are further improved.
  • the acrylonitrile-isooctyl acrylate copolymers in Examples 1 to 23 and 25 are modified with monomers bearing pyrrolidone groups, so that the copolymers contain structural units derived from monomers bearing pyrrolidone groups.
  • the acrylonitrile-isooctyl acrylate copolymer modified by the pyrrolidone group monomer has stronger adhesive performance and battery capacity retention than before modification, and the solid content of the slurry has been improved. further improvement.
  • the mass content of structural units derived from monomers containing pyrrolidone groups in Examples 1 to 23 and 25 is 0.1% to 2%, based on the total mass of acrylonitrile-isooctyl acrylate copolymer. Within this range, the copolymer improves the adhesive performance of the binder, the battery capacity retention rate, and the solid content of the slurry. In Examples 1 to 23 and 25, the mass content of structural units derived from monomers containing pyrrolidone groups is either 0.5% to 1.5%, or 0.5% to 1.0%. Within this range, the solid content of the slurry is further improved.
  • the acrylonitrile-isooctyl acrylate copolymers in Examples 1 to 23 and 25 are modified with monomers carrying pyrrolidone groups, and the mass content of structural units derived from acrylonitrile is 80% to 95%, based on the copolymer. total mass. Within this range, the copolymer improves the adhesive performance of the binder, the battery capacity retention rate, and the solid content of the slurry.
  • the acrylonitrile-isooctyl acrylate copolymers in Examples 1 to 23 and 25 are modified with monomers carrying pyrrolidone groups, and the mass content of structural units derived from isooctyl acrylate is 8% to 12%, based on The total mass of the copolymer. Within this range, the copolymer improves the adhesive performance of the binder, the battery capacity retention rate, and the solid content of the slurry.
  • Comparing Comparative Example 2 and Comparative Example 3 it can be seen that modifying the binder with a monomer bearing a group represented by Formula I can increase the solid content in the positive electrode slurry.
  • Example 9 and Example 24 it can be seen that when other conditions are consistent, modifying the binder with a monomer carrying a group represented by Formula I can increase the solid content in the cathode slurry.
  • the bonding force between the current collector and the negative electrode material layer is significantly improved, and the capacity retention rate of the battery is significantly improved.

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Abstract

粘结剂组合物、电极、电池及用电装置。粘结剂组合物包含含氟聚合物A以及共聚物B，共聚物B包含衍生自含有氰基基团的单体的结构单元以及衍生自含有酯基基团的单体的结构单元。

Description

粘结剂组合物、二次电池、电池模块、电池包及用电装置 技术领域
本申请涉及锂电池技术领域，尤其涉及一种粘结剂组合物、二次电池、电池模块、电池包及用电装置。
背景技术
近年来，锂离子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。随着锂离子电池应用的普及，对其性能和成本等也提出了更高的要求。
粘结剂是锂离子电池中的常用材料，在电池的极片、隔离膜、封装处等均有很大需求。但是现有的粘结剂成本高、粘结性差，提高了电池的成本，降低了电池的循环性能。因此，现有的粘结剂仍有待改进。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种能够降低粘结剂成本且具有优良粘结性能的粘结剂组合物。
本申请的第一方面提供了一种粘结剂组合物，其包含含氟聚合物A以及共聚物B，共聚物B包含衍生自含有氰基基团的单体的结构单元以及衍生自含有酯基基团的单体的结构单元。
由此，本申请通过以含氟聚合物A和包含衍生自含有氰基基团的单体的结构单元以及衍生自含有酯基基团的单体的结构单元的共聚物B共同作为粘结剂，相比于单独以含氟聚合物A或共聚物B作为粘结剂，可以进一步提高粘结剂的粘结性能和电池的循环性能。
在任意实施方式中，含氟聚合物A的重均分子量为60-90万，共聚物B的重均分子量为40-70万。控制聚合物的重均分子量可以兼顾 粘结剂的粘结性和可加工性。聚合物的重均分子量过低，脆性太大，使得粘结剂的粘结力不足。聚合物的重均分子量过高，难以对电极活性物质起到分散作用。而且具有不同分子量的聚合物的合理搭配，可以提高电极活性物质的分散性，进而提高电池性能。
在任意实施方式中，含氟聚合物A与共聚物B的质量比为1:4-4:1。含氟聚合物A与共聚物B在一定质量范围内的合理搭配，可以进一步提高粘结剂的粘结性能和电池的循环性能。
在任意实施方式中，含氟聚合物A选自聚偏二氟乙烯、其与四氟乙烯、六氟丙烯，三氯乙烯的共聚物中的一种或多种。
在任意实施方式中，含有氰基基团的单体选自丙烯腈、甲基丙烯腈、卤代丙烯腈、甲氧基丙烯腈中的一种或多种。
在任意实施方式中，含有酯基基团的单体选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丙酯、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。相比于含氟单体，上述含有氰基基团的单体和含有酯基基团的单体成本低，不受政策限制，能够量产，可以大幅度降低粘结剂的成本。
在任意实施方式中，共聚物B中衍生自含有氰基基团的单体的结构单元与衍生自含有酯基基团的单体的结构单元的质量比为8：1～12：1。含有氰基基团的单体可以提高共聚物B的力学强度和粘结性能，能够进一步提高电池的循环性能，少量含有酯基基团的单体能够提高共聚物B的柔性，避免极片出现脆性断裂，同时酯基具有一定的吸收电解液和保液的能力，可改善含氟聚合物A的离子电导性差的问题。
在任意实施方式中，共聚物B还包含衍生自含有式I所示基团的单体的结构单元，
Figure PCTCN2022096409-appb-000001
其中，n选自0，1，2或3。
式I所示基团中的氧元素的电负性要大于氰基中的氮元素，相比于共聚物B中的氰基基团更容易于电极活性物质和导电剂形成氢键且键能更强，可大幅度改善浆料的分散性，使得浆料中的固体物质不容易出现沉淀，提高浆料的固含量。同时，式I所示基团的加入可以进一步提高电池极片的粘结力和电池的耐循环性能。
在任意实施方式中，含有式I所示基团的单体选自N-乙烯基吡咯烷酮，N-烯丙基-2-吡咯烷酮中的一种或多种。上述单体成本低，稳定性好，易于加工合成。
在任意实施方式中，衍生自含有式I所示基团的单体的结构单元的质量含量为0.1％～2％，基于共聚物B的总质量计。共聚物B中包含适量的式I所示基团能够提高共聚物B的分散性能，使得制备的浆料不容易出现沉淀，有助于提高浆料的固含量，进而提高电极的负载量。
本申请的第三方面提供一种二次电池，包括电极组件和电解液，电极组件包括正极极片、隔离膜、负极极片，正极极片包括正极活性物质和本申请第一或第二方面的粘结剂。该电池具有更好的循环性能。
在任意实施方式中，正极活性物质为含锂的过渡金属氧化物，可选为磷酸铁锂、或它们的掺杂改性材料、或它们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。
本申请的第四方面提供一种电池模块，包括本申请第三方面的二次电池。
本申请的第五方面提供一种电池包，包括本申请第四方面的电池模块。
本申请第六方面提供一种用电装置，包括本申请第三方面的二次 电池、本申请第四方面的电池模块、本申请第五方面的电池包中的至少一种。
本申请第四方面的电池模块、第五方面的电池包因包括与第三方面的二次电池，故具有与二次电池相同的优势。
附图说明
图1为实施例1和对比例1中制备的粘结剂的粘结性能测试图；
图2为实施例1和对比例1中制备的电池的循环测试曲线；
图3是本申请一实施方式的二次电池的示意图。
图4是图3所示的本申请一实施方式的二次电池的分解图。
图5是本申请一实施方式的电池模块的示意图。
图6是本申请一实施方式的电池包的示意图。
图7是图6所示的本申请一实施方式的电池包的分解图。
图8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顶盖组件。
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)。
PVDF是一种常用的电池粘结剂，但其成本高、粘结力差，在电池循环使用的过程中由于粘结力减弱会进一步导致电池的循环性能 下降。基于上述技术问题，本申请开发出一种具有低成本，同时使极片具有优良粘结力的粘结剂，显著提高了电池的循环性能。
[粘结剂]
基于此，本申请提出了一种粘结剂组合物，其包含含氟聚合物A以及共聚物B，共聚物B包含衍生自含有氰基基团的单体的结构单元以及衍生自含有酯基基团的单体的结构单元。
在本文中，术语“粘结剂组合物”是指在分散介质(例如水)中形成胶体溶液或胶体分散液的化学化合物或聚合物的混合物。
在一些实施方式中，粘结剂的分散介质是水性溶剂，如水。
在一些实施方式中，粘接剂的分散介质是油性溶剂，油性溶剂的示例包括但不限于二甲基乙酰胺、N，N-二甲基甲酰胺、N-甲基吡咯烷酮、丙酮、碳酸二甲酯、乙基纤维素、聚碳酸酯。
在一些实施方式中，粘结剂用于将电极材料及/或导电剂固定在合适位置并将它们粘附在导电金属部件以形成电极。在一些实施方式中，电极不包含任何导电剂。
在一些实施方式中，粘结剂作为正极粘结剂，用于粘结正极活性材料及/或导电剂以形成正极电极。
在一些实施方式中，粘结剂作为负极粘结剂，用于粘结负极活性材料及/或导电剂以形成负极电极。
在本文中，术语“聚合物”一方面包括通过聚合反应(共聚、均聚)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化合物或混合物。
在本文中，术语“含氟聚合物”是指包含氟元素的聚合物。
在本文中，术语“共聚物”是指通过聚合两种或多种不同类型的单体制备的聚合物。
在本文中，术语“氰基”指的是-CN基团。
在本文中，术语“酯基”是指通式为-COOR 9结构单元的基团，R 9 选自被取代基取代或未取代的C 1-5烷基，酯基的示例包括但不限于:甲酯、乙酯、丙酯、丁酯、戊酯、异辛酯等。
在本文中，术语“取代”是指被取代基取代，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、C 1-6烷基、C 1-6烷氧基。
在一些实施方式中，共聚物B选自丙烯腈-丙烯酸甲酯共聚物、丙烯腈-2-甲基丙烯酸甲酯共聚物、丙烯腈-2-甲基丙烯酸乙酯共聚物、丙烯腈-丙烯酸乙酯共聚物、丙烯腈-丙烯酸丁酯共聚物、丙烯腈-丙烯酸异辛酯共聚物、丙烯腈-丙烯酸丁酯-丙烯酸羟乙酯共聚物、丙烯腈-丙烯酸丁酯-丙烯酸乙酯共聚物、丙烯腈-丙烯酸异戊酯-丙烯酸羟丙酯共聚物、丙烯腈-丙烯酸丁酯-丙烯酸异辛酯-甲基丙烯酸甲酯共聚物、丙烯腈-丙烯酸丁酯-丙烯酸异辛酯-甲基丙烯酸乙酯共聚物的一种或几种。在一些实施方式中，共聚物B为丙烯腈-丙烯酸异辛酯共聚物。
衍生自含有氰基基团的单体的结构单元不仅能够与集流体表面金属、还能和电极活性物质上的金属元素产生有效络合，保证电极活性物质与集流体之间产生较强粘结力。同时，衍生自含有酯基基团的单体的结构单元可提高极片的柔性，避免极片发生脆性断裂。另外，共聚物B上的氰基、酯基和含氟聚合物A中的氟元素通过氢键使得极片上的电极活性材料颗粒之间产生了更强的粘结力。
本申请通过以含氟聚合物A和包含衍生自含有氰基基团的单体的结构单元以及衍生自含有酯基基团的单体的结构单元的共聚物B共同作为粘结剂，相比于单独以含氟聚合物A或共聚物B作为粘结剂，显著提高电极活性材料与集流体、电极活性材料与导电剂、电极活性材料和/或导电剂与集流体之间粘结剂的粘结性能，显著提高电池的循环性能。
在一些实施方式中，含氟聚合物A的重均分子量为6×10 5-9×10 5，共聚物B的重均分子量为4×10 5-7×10 5。在一些实施方式中，含氟聚合物A的重均分子量选自6×10 5-8×10 5，或6×10 5-7×10 5，或7×10 5-9×10 5，或8×10 5-9×10 5。在一些实施方式中，共聚物B的重均分子量 选自4×10 5-7×10 5，或4×10 5-6×10 5，或4×10 5-5×10 5，或5×10 5-7×10 5，或6×10 5-7×10 5。
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。
控制聚合物的重均分子量可以兼顾粘结剂的粘结性和可加工性。聚合物的重均分子量过低，脆性太大，使得粘结剂的粘结力不足。聚合物的重均分子量过高，难以对电极活性物质起到分散作用。而且具有不同分子量的聚合物的合理搭配，可以提高电极活性物质的分散性，进而提高电池性能。
在一些实施方式中，含氟聚合物A与共聚物B的质量比为1:4-4:1。在一些实施方式中，含氟聚合物A与共聚物B的质量比为1:4-3:1，或1:4-2:1，或1:4-1:1，或1:2-1:4，或1:2-4:1，或1:1-4:1，或2:1-4:1，或3:1-4:1。含氟聚合物A与共聚物B在一定质量范围内的合理搭配，可以进一步提高极片粘结力和电池的循环性能。
在一些实施方式中，含氟聚合物A选自聚偏二氟乙烯、其与四氟乙烯、六氟丙烯，三氯乙烯的共聚物中的一种或多种。
在一些实施方式中，含氟聚合物A为聚偏二氟乙烯，其为乳液法合成，颗粒体积平均粒径Dv50为5-10μm，结晶度为35-40％，熔点为160-170℃。
与悬浮法合成PVDF相比，选用乳液法合成的聚偏氟乙烯单次合成产能大，成本更低。合适的分子量使得包含本申请粘结剂的浆料兼具优异的悬浮性和分散性，防止粘结剂沉降或团聚导致粘结剂在浆料中分散不均。合适的颗粒粒径可以有效降低聚偏氟乙烯的溶解时间从而减少制备浆料时的时间。合适聚偏氟乙烯的结晶度能保证良好的粘结力，同时不会引发极片的脆性问题。较高的熔点使得聚偏氟乙烯不会在涂布干燥时熔化失活。
在一些实施方式中，含有氰基基团的单体选自丙烯腈、甲基丙烯腈、卤代丙烯腈、甲氧基丙烯腈中的一种或多种。
在一些实施方式中，含有酯基基团的单体选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丙酯、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，含有酯基基团的单体选自丙烯酸异辛酯。丙烯酸异辛酯使得共聚物B具有更低的玻璃化转变温度，更好的柔韧性，利于极片的加工制造。
相比于含氟单体，上述含有氰基基团的单体和含有酯基基团的单体成本低，不受政策限制，能够量产，可以大幅度降低粘结剂的成本。
在一些实施方式中，共聚物B中衍生自含有氰基基团的单体的结构单元与衍生自含有酯基基团的单体的结构单元的质量比为8:1～12:1。在一些实施方式中，共聚物B中衍生自含有氰基基团的单体的结构单元与衍生自含有酯基基团的单体的结构单元的质量比为8:1～11:1，或8:1～10:1，或8:1～9:1，或9:1～12:1，或10:1～12:1，或11:1～12:1。
含有氰基基团的单体可以提高共聚物B的力学强度和粘结性能，能够进一步提高电池的循环性能，少量含有酯基基团的单体能够提高共聚物B的柔性，避免极片出现脆性断裂，同时酯基具有一定的吸收电解液和保液的能力，可改善含氟聚合物A的离子电导性差的问题，提高粘结剂的导离子能力。
在一些实施方式中，共聚物B还包含衍生自含有式I所示基团的单体的结构单元，
Figure PCTCN2022096409-appb-000002
其中，n选自0，1，2或3。
当n为0时，式I所示基团为
Figure PCTCN2022096409-appb-000003
当n为1时，式I 所示基团为
Figure PCTCN2022096409-appb-000004
当n为2时，式I所示基团为
Figure PCTCN2022096409-appb-000005
当n为3时，式I所示基团为
Figure PCTCN2022096409-appb-000006
式I所示基团中的氧元素的电负性要大于氰基中的氮元素，相比于共聚物B中的氰基基团更容易与电极活性物质和导电剂形成氢键且键能更强，可大幅度改善浆料的分散性，提高浆料的固含量。同时，式I所示基团的加入可以进一步提高粘结剂的粘结力和电池的循环性能。
在一些实施方式中，含有式I所示基团的单体选自N-乙烯基吡咯烷酮，N-烯丙基-2-吡咯烷酮中的一种或多种。上述单体成本低，稳定性好，易于加工合成。
在一些实施方式中，衍生自含有式I所示基团的单体的结构单元的质量含量为0.1％～2％，基于共聚物B的总质量计。在一些实施方式中，衍生自含有式I所示基团的单体的结构单元的质量含量为0.5％～2％，或为0.5％～1.5％，基于共聚物B的总质量计。共聚物B中包含适量的式I所示基团能够提高共聚物B的分散性能，使得制备的浆料不容易出现沉淀，有助于提高浆料的固含量，进而提高电极的负载量。
本申请的第二方面提供一种粘结剂，其包含共聚物C，共聚物C包含衍生自含有氰基基团的单体的结构单元、衍生自含有酯基基团的单体的结构单元、以及衍生自含有式I所示基团的单体的结构单元，
Figure PCTCN2022096409-appb-000007
其中，n选自0，1，2或3。
当n为0时，式I所示基团为
Figure PCTCN2022096409-appb-000008
当n为1时，式I所示基团为
Figure PCTCN2022096409-appb-000009
当n为2时，式I所示基团为
Figure PCTCN2022096409-appb-000010
当n为3时，式I所示基团为
Figure PCTCN2022096409-appb-000011
式I所示基团中的氧元素的电负性要大于氰基中的氮元素，相比于共聚物中的氰基基团更容易于电极活性物质和导电剂形成氢键且键能更强，可大幅度改善浆料的分散性，提高浆料的固含量。
含有氰基基团的单体能够与集流体和电极活性物质上的金属产生有效络合，保证电极活性物质与集流体之间产生较强粘结力。含有酯基基团的单体可以改善极片的脆性，避免极片发生脆性断裂。
由此，本申请通过以包含衍生自含有氰基基团的单体的结构单元、衍生自含有酯基基团的单体的结构单元、以及衍生自含有式I所示基团的单体的结构单元的共聚物C作为粘结剂，在不降低浆料的固含量的同时，降低粘结剂的成本，提高粘结剂的粘结性能和电池的循环性能。
在一些实施方式中，含有氰基基团的单体选自丙烯腈、甲基丙烯腈、卤代丙烯腈、甲氧基丙烯腈中的一种或多种。
在一些实施方式中，衍生自含有氰基基团的单体的结构单元的质量含量为80％～95％，基于共聚物C的总质量计。在一些实施方式中，衍生自含有氰基基团的单体的结构单元的质量含量为81％～95％，或为82％～95％，或为83％～95％，或为84％～95％，或为85％～95％，或 为86％～95％，或为87％～95％，或为88％～95％，或为88％～94％，或为88％～93％，或为88％～92％，或为88％～91％，基于共聚物C的总质量计。在此范围内，共聚物C可以进一步提高粘结剂的粘结性能和电池的循环性能。
在一些实施方式中，含有酯基基团的单体选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丙酯、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，含有酯基基团的单体选自丙烯酸异辛酯。丙烯酸异辛酯使得共聚物C具有更低的玻璃化转变温度，更好的柔韧性，利于极片的加工制造。
相比于含氟单体，上述含有氰基基团的单体和含有酯基基团的单体成本低，不受政策限制，能够量产，可以大幅度降低粘结剂的成本。
在一些实施方式中，衍生自含有酯基基团的单体的结构单元的质量含量为8％～12％，基于共聚物C的总质量计。在一些实施方式中，衍生自含有酯基基团的单体的结构单元的质量含量为8％～11％，或为9％～11％，基于共聚物C的总质量计。在此范围内，共聚物C可以进一步提高粘结剂的粘结性能和电池的循环性能。
在一些实施方式中，共聚物C中衍生自含有氰基基团的单体的结构单元与衍生自含有酯基基团的单体的结构单元的质量比为8：1～12：1。含有氰基基团的单体可以提高共聚物B的力学强度和粘结性能，能够进一步提高电池的循环性能，少量含有酯基基团的单体能够提高共聚物B的柔性，避免极片出现脆性断裂，同时酯基具有一定的吸收电解液和保液的能力，可改善含氟聚合物A的离子电导性差的问题。在此范围内，共聚物C可以进一步提高极片粘结力和电池循环性能。
在一些实施方式中，含有式I所示基团的单体选自N-乙烯基吡咯烷酮，N-烯丙基-2-吡咯烷酮中的一种或多种。
在一些实施方式中，衍生自含有式I所示基团的单体的结构单元的质量含量为0.1％～2％，或为0.5～1.5％，基于共聚物C的总质量计。 共聚物B中包含适量的式I所示基团能够提高共聚物B的分散性能，使得制备的浆料中包含更多的电极活性物质，有助于提高浆料的固含量。
在一些实施方式中，共聚物C的重均分子量为4×10 5-7×10 5。在一些实施方式中，共聚物C的重均分子量选自4×10 5-7×10 5，或4×10 5-6×10 5，或4×10 5-5×10 5，或5×10 5-7×10 5，或6×10 5-7×10 5。
控制共聚物C的重均分子量可以兼顾粘结剂的粘结性和可加工性。共聚物C的重均分子量过低，脆性太大，使得粘结剂的粘结力不足。共聚物C的重均分子量过高，难以对电极活性物质起到分散作用。而且具有不同分子量的共聚物的合理搭配，可以提高电极活性物质的分散性，进而提高电池性能。
在一些实施方式中，共聚物C的体积平均粒径Dv50为5-20μm。
在本文中，术语“Dv50”是指颗粒的累计粒度分布百分数达到50％时所对应的粒径。它的物理意义是粒径大于它的颗粒占50％，小于它的颗粒也占50％，Dv50也叫中位径或中值粒径。
共聚物C的平均粒径Dv50过大会造成溶解困难，浆料分散性不好带来导电剂或者电极活性物质与粘结剂形成团聚堵塞滤网影响生产，团聚体被冲刷到涂布头会产生涂布颗粒划痕影响涂布质量。合适的平均粒径Dv50有助于提高共聚物C在溶剂中的溶解速度，提高极片的加工效率。
在一些实施方式中，共聚物C的特性粘度为0.8-1.1dl/g。
在本文中，术语“特性粘度”是指高分子溶液粘度的最常用的表示方法。定义为当高分子溶液浓度趋于零时的比浓粘度。即表示单个分子对溶液粘度的贡献，是反映高分子特性的粘度，其值不随浓度而变。本发明的特性粘度是指在30℃在N,N-二甲基乙酰胺中测量的特性粘度。
本申请中采用以下方法测试特性粘度：首先，称取共聚物C成品粉末样品m1(0.15-0.17g),置于100mL锥形瓶内；用移液管加入V1(50-60ml)N,N-二甲基乙酰胺，密封锥形瓶口，并计算溶液浓度 C0＝m1/V1,将锥形瓶放入60℃恒温水浴锅内溶解2.5h；将溶解完的样品溶液用砂芯过滤器过滤一下，防止颗粒杂质堵塞乌式粘度。其次，用一次性塑料吸管吸取已过滤的N,N-二甲基乙酰胺润洗洁净的乌式粘度计，至少用溶剂润洗4-5次；用移液管吸取10mL N,N-二甲基乙酰胺注入乌氏粘度计内；将乌氏粘度计放入30.0℃±0.1℃恒温水浴槽中，保持15-20min后测量流出的时间并记录t0。最后用一次性塑料吸管吸取已过滤的第一步制取的胶液，用胶液至少润洗塑料吸管4-5次；用移液管吸取10mL胶液注入乌氏粘度计内；将乌氏粘度计放入30.0℃±0.1℃恒温水浴槽中，保持15-20min后测量流出的时间并记录t1，特性粘度测量值为(t1/t0)/C0。
控制共聚物C的特性粘度在合适范围内可以使得共聚物C兼具优异的粘结性能和加工性能。避免因粘度过低，而无法起到有效粘结，同时避免因粘度过高，而引起浆料搅拌、制备、涂布困难。
本申请的第三方面提供一种粘结剂的制备方法，其包括以下步骤：
提供含有氰基基团的单体、含有酯基基团的单体、以及含有式I所示基团的单体，
Figure PCTCN2022096409-appb-000012
其中，n选自0，1，2或3；
在可聚合条件下将含有氰基基团的单体、含有酯基基团的单体、以及含有式I所示基团的单体聚合制备共聚物C。
在一些实施方式中，共聚物C是以阴离子型的乳化剂通过常规的乳液聚合共聚得到的。
在一些实施方式中，在可聚合条件下将含有氰基基团的单体、含有酯基基团的单体、以及含有式I所示基团的单体聚合制备共聚物C包括在聚合压力下将第一份量的含有氰基基团的单体、含有酯基基团的单体、以及含有式I所示基团的单体与第一份量的反应溶剂，第一 份量的乳化剂，第一份量的pH缓冲剂，第一份量的引发剂在第一聚合温度下进行第一阶段反应；以及在第一阶段反应后在体系中加入第二份量的含有氰基基团的单体、含有酯基基团的单体、以及含有式I所示基团的单体与第二份量的反应溶剂，第二份量的乳化剂，第二份量的pH缓冲剂，第二份量的引发剂在第二聚合温度下进行第二阶段反应。
在一些实施方式中，乳化剂选自全氟辛酸类的碱金属盐或烷基类酸盐的一种或多种。全氟辛酸类的碱金属盐选自全氟辛酸钠、全氟辛酸钾的一种或多种。烷基类酸盐选自烷基硫酸盐、烷基磺酸盐的一种或多种。
在一些实施方式中，引发剂选自过氧化物，过氧化物选自过硫酸盐类无机过氧化物、过氧化物碳酸酯类的一种或多种，无机过氧化物选自过硫酸铵、过硫酸钾的一种或多种，过氧化物碳酸酯类选自二异丙基过氧化二碳酸酯。
在一些实施方式中，反应溶剂为去离子水。
在一些实施方式中，pH缓冲剂选自氨水、碳酸钾、碳酸氢钾的一种或多种。
在一些实施方式中，第一份量的含有氰基基团的单体、含有酯基基团的单体、以及含有式I所示基团的单体为各单体配方量75-90％，第一份量的反应溶剂为第一阶段反应加入的单体总量的70-80％，第一份量的乳化剂为第一阶段反应加入的单体总量的0.2-0.3％，第一份量的pH缓冲剂为第一阶段反应加入的单体总量的0.05-0.2％，第一份量的引发剂为第一阶段反应加入的单体总量的0.15-1％。第一聚合温度为70-80℃，第一阶段反应的反应时间为2-3小时。
在一些实施方式中，第二份量的含有氰基基团的单体、含有酯基基团的单体、以及含有式I所示基团的单体为各单体配方量10-25％，第二份量的反应溶剂为第二阶段反应加入的单体总量的20-30％，第二份量的乳化剂为第二阶段反应加入的单体总量的0.05-0.1％，第二份量的引发剂为第二阶段反应加入的单体总量的0.05-0.3％，第二聚合温度为85-90℃，第二阶段反应的反应时间为3-4小时。
在一些实施方式中，含有氰基基团的单体与所述含有酯基基团的单体的质量比为8:1～12:1，且含有式I所示基团的单体的质量含量为0.1％～2％，基于共聚物C的总质量计。
在一些实施方式中，含有氰基基团的单体选自丙烯腈、甲基丙烯腈、卤代丙烯腈、甲氧基丙烯腈中的一种或多种；和/或含有酯基基团的单体选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丙酯、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；和/或含有式I所示基团的单体选自N-乙烯基吡咯烷酮，N-丙烯基吡咯烷酮中的一种或多种。
该方法制备单体成本低，反应条件温和，能够降低粘结剂的成本。
[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，所述正极膜层包括正极活性材料。
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、本申请的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其他粘结剂。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：将上述用于制备负极极片的组分，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；将负极浆料涂覆在负极集流体上，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。
[二次电池]
本申请提供一种二次电池，包括电极组件和电解液，电极组件包括正极极片、隔离膜、负极极片，正极极片包括正极活性物质和本申请任意实施方式中的粘结剂或本申请任意实施方式的制备方法制备的粘结剂。该二次电池具有更好的循环性能。
在一些实施方式中，正极活性物质为含锂的过渡金属氧化物，可选为磷酸铁锂、或它们的掺杂改性材料、或它们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。
在一些实施方式中，含锂的过渡金属氧化物可选为钴酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂、硅酸铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、尖晶石型锰酸锂、尖晶石型镍锰酸锂、钛酸锂，或它们的掺杂改性材料、或它 们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。
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。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。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。
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3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4，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。
本申请的第四方面中提供一种电极，包括电极活性物质和任意实施方式中的粘结剂组合物或粘结剂，所述电极活性物质可选为正极活性物质，所述正极活性物质为含锂的过渡金属氧化物。在一些实施方式中，含锂的过渡金属氧化物可选为钴酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂、硅酸 铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、尖晶石型锰酸锂、尖晶石型镍锰酸锂、钛酸锂，或它们的掺杂改性材料、或它们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。在一些实施方式中，含锂的过渡金属氧化物可选为磷酸铁锂、或它们的掺杂改性材料、或它们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。
该电极具有更高的粘结力，使得电池具有更好的循环性能。
[电池模块]
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5是作为一个示例的电池模块4。参照图5，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。
[电池包]
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6和图7是作为一个示例的电池包1。参照图6和图7，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。
[用电装置]
本申请的第六方面提供一种用电装置，包括任意实施方式中的二次电池，任意实施方式中的电池模块或任意实施方式中的电池包。该用电装置续航更持久。
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8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。
实施例1
1)包含共聚物C的粘结剂的制备
共聚物C的制备方法如下：聚合釜为10L的不锈钢高压釜，转速为100r/min,首先检查聚合体系的密封性，然后对高压釜抽真空充氮以排氧，重复3次。加入2000g去离子水及1.6g氨水，3.2g烷基硫酸钠,再加入1408g丙烯腈单体、176g丙烯酸异辛酯单体、16g N-乙烯基吡咯烷酮单体，抽真空至聚合压力4.2Mpa，升温至55℃，静置0.8h后加入8g的过硫酸铵，升温至75℃，搅拌下聚合反应2-3h.向聚合釜中连续加入352g丙烯腈单体、44g丙烯酸异辛酯单体、4g N-乙烯基吡咯烷酮单体、400g去离子水、1.6g烷基硫酸钠、0.8g过硫酸铵，提高温度到90℃，维持反应4h。通过闪蒸的方式得到聚合 的物品，再通过去离子水洗涤至洗涤液的电导率小于1*10 -8s/cm，经过真空干燥后得到N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物。制备得到的共聚物其重均分子量为70万，颗粒粒径Dv50为15μm，特性粘度为1.1dl/g。
粘结剂的制备方法如下：取4g聚偏氟乙烯(含氟聚合物A)和4g N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物加入到250g的N-甲基吡咯烷酮溶液中，在搅拌分散机上以500r/min转速搅拌90min，搅拌结束后在超声清洗机上除泡30min。其中，聚偏氟乙烯为东阳光公司生产的601A产品，乳液法合成，重均分子量为90万，颗粒粒径Dv50为20μm，结晶度为40％，熔点为170℃。
2)扣式电池的制备
将398g磷酸铁锂和2.8g导电炭黑加入到玛瑙研钵中，干混15min。将干混后的产物加入到粘结剂中，在搅拌分散机上以1200r/min转速搅拌90min，制得锂电池正极浆料。
将上述浆料，刮涂到涂碳铝箔上面，110℃烘烤15min，冷压后裁剪成直径15mm的圆片，再与金属锂片、隔离膜、电解液制作成扣式电池。
3)隔离膜
以聚丙烯膜作为隔离膜。
4)电解液的制备
在氩气气氛手套箱中(H 2O<0.1ppm，O 2<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LiPF 6锂盐溶解于有机溶剂中，搅拌均匀，配置1M LiPF 6EC/EMC溶液得到电解液。
实施例2～25的电池和对比例1的扣式电池与实施例1的扣式电池制备方法相似，但是调整了共聚物C制备的原料和配比或者粘结剂中各组分的配比，具体参数见表1。
实施例2～7中调整聚偏氟乙烯和共聚物C的质量比，其他参数与实施例1保持一致，具体参数见表1。
实施例8～11中调整N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共 聚物中丙烯腈和丙烯酸异辛酯的单体聚合比例，其他参数与实施例1保持一致，具体参数见表1。
实施例12～13中调整N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物中丙烯腈和丙烯酸异辛酯的单体聚合比例，设置聚偏氟乙烯和N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物的质量比为2：1，其他参数与实施例1保持一致，具体参数见表1。
实施例14～15中调整N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物中丙烯腈和丙烯酸异辛酯的单体聚合比例，设置聚偏氟乙烯和N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物的质量比为3：1，其他参数与实施例1保持一致，具体参数见表1。
实施例16～17中调整N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物中丙烯腈和丙烯酸异辛酯的单体聚合比例，设置聚偏氟乙烯和N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物的质量比为4：1，其他参数与实施例1保持一致，具体参数见表1。
实施例18～20中调整聚合物B中加入的N-乙烯基吡咯烷酮的质量，设置N-乙烯基吡咯烷酮-丙烯腈-丙烯酸异辛酯共聚物中丙烯腈和丙烯酸异辛酯单体的摩尔比为10：1，其他参数与实施例1保持一致，具体参数见表1。
实施例21～22中共聚物制备过程中，再进行二次补液温度升高到90℃后，反应时间从4h依次调整为3h、2.5h，设置N-乙烯基吡咯烷酮改性丙烯腈-丙烯酸异辛酯共聚物中丙烯腈和丙烯酸异辛酯单体的摩尔比为10：1，其他参数与步骤与实施例1保持一致，具体参数见表1。
实施例23中采用N-烯丙基-2-吡咯烷酮改性丙烯腈-丙烯酸异辛酯共聚物，其他参数与实施例1保持一致，具体参数见表1。
实施例24中在制备共聚物的过程中不加入N-乙烯基吡咯烷酮，设置丙烯腈-丙烯酸异辛酯共聚物中丙烯腈和丙烯酸异辛酯单体的摩尔比为10：1，其他参数与实施例1保持一致，具体参数见表1。
实施例25中聚偏氟乙烯使用东阳光公司生产的401A产品，其重均分子量为60万，其他步骤与实施例1保持一致，具体参数见表 1.
对比例1中，采用单独的聚偏氟乙烯作为粘结剂；对比例2中采用实施例9中制备的单独的N-乙烯基吡咯烷酮改性丙烯腈-丙烯酸异辛酯共聚物作为粘结剂，对比例3中采用实施例24中制备的单独的丙烯腈-丙烯酸异辛酯共聚物作为粘结剂，其他步骤同实施例1，具体参数见表1。
上述实施例1～25、对比例1～3的粘结剂的相关参数如下述表1所示。
另外，将上述实施例1～25和对比例1～3中得到的极片和电池进行性能测试。测试方法如下，测试结果见表1。
1、粘结剂的结构单元种类测试
采用压片透射法，将样品进行KBr压片，通过透射法扣除KBr背景空白，得到样品测试谱图，仪器型号：Nicolet 5700(美国Thermo Nicolet公司)，标准线性度：优于0.07％，分辨率：0.09cm -1，波数范围：400～4000cm -1，灵敏度<9.65*10 -5Abls。用于检测分子的结构和化学键。
2、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)。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 HT5 DMF7.8*300mm+Styragel HT4)。用纯化后的N-甲基吡咯烷酮(NMP)溶剂配置3.0％的粘结剂胶液，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。
3、粘结力测试(正极极片活性材料层与正极集流体之间)
参考国标GBT 2790-1995《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30mm*长度为100-160mm的试样，将专用双面胶贴于钢板上，胶带宽度20mm*长度90-150mm。将前面截取的极片试样贴在双面胶上，测试面朝下，后用压辊沿同一个方向滚压三次。
将宽度与极片等宽，长度大于试样长度80-200mm的纸带插入极片下方，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。得到如附图1所示的实施例1和对比例1的粘结力对比数据
4、电池容量保持率测试
以实施例1为例，电池容量保持率测试过程如下：在25℃下，将实施例1对应的电池，以1/3C恒流充电至3.65V，再以3.65V恒定电压充电至电流为0.05C，搁置5min，再以1/3C放电至2.5V，所得容量记为初始容量C0。对上述同一个电池重复以上步骤，并同时记录循环第n次后电池的放电容量Cn，则每次循环后电池容量保持率Pn＝Cn/C0*100％，以P1、P2……P100这100个点值为纵坐标，以对应的循环次数为横坐标，得到如附图2所示的实施例1和对比例1的电池容量保持率与循环次数的曲线图。
该测试过程中，第一次循环对应n＝1、第二次循环对应n＝2、……第100次循环对应n＝100。表1中实施例1对应的电池容量保持率数据是在上述测试条件下循环500次之后测得的数据，即P500的值。对比例1以及其他实施例的测试过程同上。
5、浆料固含量测试
固含量测试方法：准备一个玻璃培养皿并记录重量m 1,取一部分制得的正极浆料放到玻璃培养皿中并记录总重量m 2，将装有正极浆料的培养皿放到干燥箱中加热，加热温度120℃，加热时间1h。将干燥后的培养皿称取并记录重量m 3,固含量＝(m 3-m 1)/(m 2-m 1)*100％。
Figure PCTCN2022096409-appb-000013
Figure PCTCN2022096409-appb-000014
Figure PCTCN2022096409-appb-000015
Figure PCTCN2022096409-appb-000016
如图1和图2所示，实施例1相对于对比例1，由于加入吡咯烷酮基团的单体改性后的丙烯腈-丙烯酸异辛酯共聚物，粘结剂的粘结性能和电池的容量保持率都有所提升。
根据表1结果可知，实施例1～25均提供了一种粘结剂组合物，包含聚偏二氟乙烯以及包含衍生自丙烯腈的结构单元以及衍生自丙烯酸异辛酯的结构单元的丙烯腈-丙烯酸异辛酯共聚物。相对于对比例1～3，其均取得了良好的效果，提高了粘结剂的粘结性能和电池容量保持率。
实施例1～25中的聚偏二氟乙烯的重均分子量为60～90万，丙烯腈-丙烯酸异辛酯共聚物的重均分子量为40～70万。相对于对比例1～3，其均取得了良好的效果，提高了粘结剂的粘结性能和电池容量保持率。
实施例1～25中，粘结剂组合物中聚偏二氟乙烯与丙烯腈-丙烯酸异辛酯共聚物的质量比为1:4～4:1。相对于对比例1～3，其均取得了良好的效果，提高了粘结剂的粘结性能和电池容量保持率。
实施例1～25中的丙烯腈-丙烯酸异辛酯共聚物中衍生自丙烯腈的结构单元与衍生自丙烯酸异辛酯的结构单元的质量比为8:1～12:1，其均取得了良好的效果，提高了粘结剂的粘结性能和电池容量保持率，丙烯腈-丙烯酸异辛酯共聚物中衍生自丙烯腈的结构单元与衍生自丙烯酸异辛酯的结构单元的质量比为8:1～10:1时，粘结剂的粘结性能和电池容量保持率有了进一步提升。
实施例1～23、25中的丙烯腈-丙烯酸异辛酯共聚物采用带有吡咯烷酮基团的单体改性，使得其共聚物包含衍生自带有吡咯烷酮基团的单体的结构单元。吡咯烷酮基团的单体改性后的丙烯腈-丙烯酸异辛酯共聚物相比于改性前具有更强的粘结剂的粘结性能和电池容量保持率，且浆料的固含量得到了进一步提升。
实施例1～23、25中衍生自含有吡咯烷酮基团的单体的结构单元的质量含量为0.1％～2％，基于丙烯腈-丙烯酸异辛酯共聚物的总质量计。该范围内，共聚物使得粘结剂的粘结性能、电池容量保持率以及 浆料的固含量均得到了提升。实施例1～23、25中衍生自含有吡咯烷酮基团的单体的结构单元的质量含量或为0.5％～1.5％，或为0.5％～1.0％。该范围内，浆料的固含量得到了进一步提升。
实施例1～23、25中的丙烯腈-丙烯酸异辛酯共聚物采用带有吡咯烷酮基团的单体改性，衍生自丙烯腈的结构单元的质量含量为80％～95％，基于共聚物的总质量计。该范围内，共聚物使得粘结剂的粘结性能、电池容量保持率以及浆料的固含量得到了提升。
实施例1～23、25中的丙烯腈-丙烯酸异辛酯共聚物采用带有吡咯烷酮基团的单体改性，衍生自丙烯酸异辛酯的结构单元的质量含量为8％～12％，基于共聚物的总质量计。该范围内，共聚物使得粘结剂的粘结性能、电池容量保持率以及浆料的固含量得到了提升。
通过对比例2和对比例3的比较可知，用带有式I所示的基团的单体对粘结剂进行改性，能够提高正极浆料中的固含量。通过比较实施例9和实施例24可知，在其他条件一致的情况下，用带有式I所示的基团的单体对粘结剂进行改性，能够提高正极浆料中的固含量，对应集流体与负极材料层之间的粘结力显著改善，电池的容量保持率的显著提升。
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 (15)

  1. 一种粘结剂组合物，其特征在于，其包含含氟聚合物A以及共聚物B，所述共聚物B包含衍生自含有氰基基团的单体的结构单元以及衍生自含有酯基基团的单体的结构单元。
  2. 根据权利要求1所述的粘结剂组合物，其特征在于，所述含氟聚合物A的重均分子量为60～90万，所述共聚物B的重均分子量为40～70万。
  3. 根据权利要求1所述的粘结剂组合物，其特征在于，所述含氟聚合物A与所述共聚物B的质量比为1:4～4:1。
  4. 根据权利要求1或2所述的粘结剂组合物，其特征在于，所述含氟聚合物A选自聚偏二氟乙烯、其与四氟乙烯、六氟丙烯，三氯乙烯的共聚物中的一种或多种。
  5. 根据权利要求1-3中任一项所述的粘结剂组合物，其特征在于，所述含有氰基基团的单体选自丙烯腈、甲基丙烯腈、卤代丙烯腈、甲氧基丙烯腈中的一种或多种。
  6. 根据权利要求1-4中任一项所述的粘结剂组合物，其特征在于，所述含有酯基基团的单体选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丙酯、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. 根据权利要求1-5中任一项所述的粘结剂组合物，其特征在于，所述共聚物B中所述衍生自含有氰基基团的单体的结构单元与所述衍生自含有酯基基团的单体的结构单元的质量比为8:1～12:1，或 为8:1～10:1。
  8. 根据权利要求1-6中任一项所述的粘结剂组合物，其特征在于，所述共聚物B还包含衍生自含有式I所示基团的单体的结构单元，
    Figure PCTCN2022096409-appb-100001
    其中，n选自0，1，2或3。
  9. 根据权利要求7所述的粘结剂组合物，其特征在于，所述含有式I所示基团的单体选自N-乙烯基吡咯烷酮，N-烯丙基-2-吡咯烷酮中的一种或多种。
  10. 根据权利要求7所述的粘结剂组合物，其特征在于，所述衍生自含有式I所示基团的单体的结构单元的质量含量为0.1％～2％，或为0.5％～1.5％，或为0.5％～1.0％，基于所述共聚物B的总质量计。
  11. 一种二次电池，其特征在于，包括电极组件和电解液，所述电极组件包括正极极片、隔离膜、负极极片，所述正极极片包括正极活性物质和权利要求1～10中任一项所述的粘结剂。
  12. 根据权利要求11所述的二次电池，其特征在于，所述正极活性物质为含锂的过渡金属氧化物，可选为磷酸铁锂、或它们的掺杂改性材料、或它们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。
  13. 一种电池模块，其特征在于，包括权利要求11或12所述的二次电池。
  14. 一种电池包，其特征在于，包括权利要求13所述的电池模块。
  15. 一种用电装置，其特征在于，包括选自权利要求11或12所述的二次电池、权利要求13所述的电池模块或权利要求14所述的电池包中的至少一种。
PCT/CN2022/096409 2022-05-31 2022-05-31 粘结剂组合物、二次电池、电池模块、电池包及用电装置 WO2023230895A1 (zh)

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