WO2025025762A1 - 聚合物、其制备方法、正极极片、二次电池、用电装置 - Google Patents

聚合物、其制备方法、正极极片、二次电池、用电装置 Download PDF

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WO2025025762A1
WO2025025762A1 PCT/CN2024/095211 CN2024095211W WO2025025762A1 WO 2025025762 A1 WO2025025762 A1 WO 2025025762A1 CN 2024095211 W CN2024095211 W CN 2024095211W WO 2025025762 A1 WO2025025762 A1 WO 2025025762A1
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positive electrode
polymer
group
segment
formula
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English (en)
French (fr)
Inventor
石瀚文
王泽江
黄继春
王星会
倾亚龙
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority claimed from CN202311098921.1A external-priority patent/CN119431767A/zh
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Priority to KR1020257024969A priority Critical patent/KR20250128354A/ko
Priority to EP24847725.9A priority patent/EP4741441A1/en
Priority to JP2026500771A priority patent/JP2026524911A/ja
Publication of WO2025025762A1 publication Critical patent/WO2025025762A1/zh
Priority to US19/454,421 priority patent/US20260152604A1/en
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
    • C08G65/2618—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing nitrogen
    • C08G65/2633—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing nitrogen the other compounds containing amide groups
    • 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
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
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    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/32—Polymers modified by chemical after-treatment
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/32—Polymers modified by chemical after-treatment
    • C08G65/329—Polymers modified by chemical after-treatment with organic compounds
    • C08G65/333—Polymers modified by chemical after-treatment with organic compounds containing nitrogen
    • C08G65/3332—Polymers modified by chemical after-treatment with organic compounds containing nitrogen containing carboxamide group
    • C08G65/33324—Polymers modified by chemical after-treatment with organic compounds containing nitrogen containing carboxamide group acyclic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/32—Polymers modified by chemical after-treatment
    • C08G65/329—Polymers modified by chemical after-treatment with organic compounds
    • C08G65/335—Polymers modified by chemical after-treatment with organic compounds containing phosphorus
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/32—Polymers modified by chemical after-treatment
    • C08G65/329—Polymers modified by chemical after-treatment with organic compounds
    • C08G65/335—Polymers modified by chemical after-treatment with organic compounds containing phosphorus
    • C08G65/3353—Polymers modified by chemical after-treatment with organic compounds containing phosphorus containing oxygen in addition to phosphorus
    • 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
    • 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a polymer, a preparation method thereof, a positive electrode sheet, a secondary battery, and an electrical device.
  • secondary batteries have been widely used in energy storage power systems such as hydropower, thermal, wind and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • the pole pieces in secondary batteries are often prepared by coating a slurry containing active materials on a current collector and then drying it.
  • Increasing the solvent content in the slurry and reducing the solid content of the slurry are effective means to optimize the uniformity of slurry dispersion and improve the quality of slurry coating.
  • slurries with high solvent content require long drying times and high manufacturing costs. How to ensure the uniformity of slurry dispersion while increasing the solid content of the slurry, and thereby effectively increase the maximum solid content of the slurry, is a technical problem that urgently needs to be solved in this field.
  • the present application is made in view of the above-mentioned problems, and an object of the present application is to provide a dispersant capable of increasing the maximum solid content of a slurry.
  • the first aspect of the present application provides a polymer, wherein the polymer comprises a structure shown in Formula I,
  • X comprises a phosphate group or a phosphite group
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment or a polyester segment
  • R 2 comprises an organic segment.
  • the polymer can effectively increase the maximum solid content of the positive electrode slurry, shorten the filtration time, improve the production efficiency and quality of the electrode, and improve the flexibility of the electrode.
  • the organic segment of R 2 comprises at least one of an amide group, an amino group, and an aromatic group.
  • the nitrogen-containing groups or aromatic groups in the polymer help to improve the anchoring effect between the polymer and the positive electrode active material, making the polymer particularly suitable for carbon-coated positive electrode active materials, further improving the versatility of the polymer as a dispersant, and more effectively exerting the dispersing effect of the polymer by increasing the anchoring sites of the dispersant, thereby further increasing the maximum solid content of the slurry, improving the quality of electrode molding, and reducing costs and increasing efficiency.
  • the organic segment of R 2 further includes a C 2-12 hydrocarbon group.
  • C2-12 hydrocarbon groups in the polymer helps to further improve the anchoring effect between the polymer and the carbon-modified positive electrode active material.
  • the hydrocarbon groups can effectively anchor to the carbon on the positive electrode active material, increasing the dispersion of the anchoring sites of the polymer on the positive electrode active material, thereby further improving the application range of the polymer dispersant, increasing the maximum solid content of the slurry, optimizing the quality of electrode forming while reducing costs and increasing efficiency.
  • R 2 comprises the structure shown in Formula II
  • R4 and R5 are randomly copolymerized, R4 includes at least one of C2-12 alkylene group and C3-13 amide group, and R5 includes At least one of;
  • R 6 a and R 6 b include at least one of hydrogen and C 1-4 alkyl, 1 ⁇ s ⁇ 6, and 1 ⁇ t ⁇ 10.
  • the organic chain segments of the above structure can more effectively play an anchoring role through copolymerization of nitrogen-containing groups and hydrocarbon groups, enhance the dispersion effect of the polymer, and effectively increase the solid content of the slurry.
  • R 2 comprises a structure shown in Formula III
  • R 6 includes C 2-12 alkylene group
  • R 7 includes At least one of; wherein, q5 and q6 each independently include any integer between 0-4, 1 ⁇ n ⁇ 6.
  • the organic chain segments of the above structure can more effectively play an anchoring role through the alternating copolymerization of nitrogen-containing groups and hydrocarbon groups, enhance the dispersion effect of the polymer, and effectively increase the solid content of the slurry.
  • the terminal group of R 2 comprises at least one of -C(O)-NH 2 and -CH 2 -NH 2 .
  • the polymer whose terminal groups include -C(O)-NH 2 and -CH 2 -NH 2 can play a more effective dispersing role, increase the maximum solid content of the slurry, and thus improve the molding quality and efficiency of the pole piece.
  • At least one of R 1 and R 3 comprises a polyether segment.
  • both R 1 and R 3 comprise a polyether segment.
  • At least one of R 1 and R 3 comprises a polyether segment represented by formula IV
  • EO represents -CH 2 -CH 2 -O-
  • PO represents -CH(CH 3 )-CH 2 -O-, 4 ⁇ m1 ⁇ 50, 4 ⁇ n1 ⁇ 50.
  • the polyether segment with the above structure has suitable steric hindrance and low glass transition temperature, which can more effectively reduce the order and glass transition temperature of the binder crystallization in the positive electrode slurry, thereby reducing the crystallinity of the binder and improving the flexibility of the electrode.
  • the uniformity and flexibility of the electrode are improved, thereby improving the safety performance and ultimate compaction density of the battery, so that the positive electrode active material loading of the battery can be increased, which helps to further improve the energy density of the battery.
  • terminal groups of the polyether segments include aromatic groups.
  • the aromatic group has excellent compatibility with the carbon layer on the surface of the positive electrode active material, which helps to further improve the anchoring effect between the polymer and the carbon-modified positive electrode active material.
  • the aromatic group and the carbon on the positive electrode active material can be effectively anchored to increase the dispersion of the anchoring sites of the polymer on the positive electrode active material, thereby further improving the application range of the polymer dispersant, increasing the maximum solid content of the slurry, optimizing the quality of electrode molding, and reducing costs and increasing efficiency.
  • X comprises a phosphate group.
  • Phosphate polymers can more effectively increase the solid content of the slurry, shorten the filtration time, and improve the flexibility of the electrode; and phosphate polymers have better stability, and can effectively improve the battery's cycle capacity retention rate on the basis of improving the slurry's dispersibility.
  • the polymer comprises at least one of the polymers represented by the following formula:
  • R 1 and R 3 comprises a block copolymer polyether segment represented by formula IV
  • EO represents -CH 2 -CH 2 -O-
  • PO represents -CH(CH 3 )-CH 2 -O-
  • R 6 and R 4 each independently include at least one of C 4-8 alkylene and C 4-8 alkenylene.
  • the polymer is represented by the following formula:
  • R2 comprises at least one of hydrogen, aryl, substituted or unsubstituted alkyl, and an organic segment containing an amino group or an amide group,
  • At least one of R 1 and R 3 comprises a block copolymer polyether segment represented by formula IV
  • EO represents -CH 2 -CH 2 -O-
  • PO represents -CH(CH 3 )-CH 2 -O-
  • the terminal group of the polyether segment includes phenyl.
  • the weight average molecular weight of the polymer is 1000-10000, and optionally 2000-5000.
  • the polymer with a weight average molecular weight within the above range can not only play an excellent dispersibility and further increase the solid content of the slurry, but also make the slurry have excellent flow properties, reduce the coating time, and improve the uniformity and speed of coating.
  • the polymer with a weight average molecular weight of 2000-5000 can play a more effective dispersing role, increase the maximum solid content of the slurry, and shorten the filtration time.
  • the second aspect of the present application provides a method for preparing a polymer, the preparation method comprising:
  • the compound represented by Formula VI is reacted with R 3 OH, R 1 OH, water, and a polymerizable monomer containing an unsaturated bond to prepare a polymer having a structure represented by Formula I.
  • X comprises a phosphate group or a phosphite group
  • X 1 , X 2 , and X 3 all comprise halogen
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment or a polyester segment
  • R 2 comprises an organic segment.
  • the preparation method comprises the following steps:
  • the intermediate product is subjected to a second reaction with a polymerization monomer containing at least one of an amide containing an unsaturated bond and an amine containing an unsaturated bond to prepare the polymer.
  • the second reaction specifically comprises the following steps:
  • the intermediate product undergoes an addition reaction with at least one of an amide containing an unsaturated bond and an amine containing an unsaturated bond, and then undergoes a substitution reaction with a halogen-substituted organic alcohol;
  • the polymer is prepared by cycling the addition reaction and substitution reaction in sequence for multiple times;
  • R 2 comprises the structure shown in formula III
  • R 6 includes C 2-12 hydrocarbon group
  • R 7 includes At least one of; wherein, q5 and q6 each independently include any integer between 0-4, 1 ⁇ n ⁇ 6.
  • the preparation method further comprises the following steps:
  • the intermediate product is reacted with (i) at least one of an amide containing an unsaturated bond and an amine containing an unsaturated bond, and (ii) at least one of a hydrocarbon monomer containing an unsaturated bond and a cyclic amide monomer to prepare the polymer, wherein R 2 comprises a structure shown in Formula II
  • R4 and R5 are randomly copolymerized, R4 includes at least one of a C2-12 hydrocarbon group and a C3-13 amide group, and R5 includes At least one of;
  • R 6 a and R 6 b include at least one of hydrogen and C 1-4 alkyl, 1 ⁇ s ⁇ 6, and 1 ⁇ t ⁇ 10.
  • Another aspect of the present application provides a method for preparing a polymer, the method comprising: reacting a compound represented by Formula VI with a raw material including R 3 OH and R 1 OH to prepare a polymer having a structure represented by Formula I,
  • X comprises a phosphate group or a phosphite group
  • X 1 , X 2 , and X 3 all comprise halogen
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment, and the terminal group of at least one of the polyether segments comprises an aromatic group
  • R 2 comprises an organic segment.
  • the third aspect of the present application provides a polymer or a polymer prepared by the preparation method of any embodiment as a dispersant.
  • the fourth aspect of the present application provides a positive electrode slurry, comprising a dispersant, wherein the dispersant comprises the polymer of the first aspect of claim or the polymer prepared by the preparation method of the second aspect.
  • the positive electrode slurry has a high solid content, which helps to improve the molding efficiency and molding quality of the positive electrode film layer, and improve the electrochemical performance and processing efficiency of the battery.
  • the positive electrode slurry includes a positive electrode active material, and the positive electrode active material includes at least one of a lithium phosphate and a carbon-modified material thereof; optionally, the positive electrode active material includes at least one of lithium iron phosphate and a doped material thereof, lithium manganese iron phosphate and a doped material thereof, a carbon-coated material of lithium iron phosphate and a doped material thereof, and a carbon-coated material of lithium manganese iron phosphate and a doped material thereof.
  • the polymer is negatively charged and can interact with the weakly acidic lithium phosphate through electrostatic interaction.
  • the mutual anchoring is further strengthened, thereby improving the dispersion effect of the polymer on the lithium-containing phosphate.
  • the lithium-containing phosphate has poor conductivity. Therefore, in the preparation process of the positive electrode active material, the carbon layer is often coated with organic substances such as sintered glucose and sucrose to improve its conductivity.
  • the polymer also has a group that is mutually anchored with the carbon coating layer, and has an excellent dispersion effect on the carbon-modified lithium-containing phosphate, which can further improve the dispersibility of its slurry, thereby increasing the maximum solid content of the slurry.
  • the positive electrode active material includes a core and a carbon coating layer, wherein the carbon coating layer covers at least a portion of the surface of the core, wherein the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer is not less than 0.2, and can be optionally not less than 0.5, and can be optionally not less than 0.8.
  • the formation of a carbon coating on the surface of the inner core can improve the conductivity of the positive electrode active material.
  • the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating on the surface of the inner core is not less than 0.5, the orderliness of the structure of the carbon coating of the positive electrode active material is relatively high, and the pore structure of the carbon coating has a relatively high density and a relatively small pore size distribution range.
  • the carbon coating layer with a molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms of not less than 0.5 has a high degree of graphitization, which makes the positive electrode active material easy to agglomerate and difficult to effectively disperse during the pulping process.
  • the dispersant provided in the embodiment of the present application and the carbon coating layer with a high degree of graphitization have rich anchoring groups, which are particularly suitable for the dispersion of positive electrode active materials with a high degree of graphitization of the coating layer. The combination of the two can simultaneously improve the performance and processing performance of the battery.
  • the thickness of the carbon coating layer is not greater than 15nm; optionally, the thickness of the carbon coating layer is not greater than 10nm, and optionally, the thickness of the carbon coating layer is 4nm-8nm.
  • the carbon coating layer within the above thickness range can form a thinner carbon coating layer on the surface of the core, which can effectively improve the conductivity of the positive electrode active material and improve the compaction performance when using the positive electrode active material to prepare the battery pole piece.
  • the mass content of the polymer is 0.1%-2.0%, and can be optionally 0.2%-1.0%.
  • the polymer within the above range can not only play an effective dispersing role, but also take into account the volume energy density of the battery, and will not have a serious negative impact on the electrochemical performance of the battery.
  • the positive electrode slurry includes a binder, and the binder includes a vinylidene fluoride polymer with a weight average molecular weight of not less than 300,000.
  • the weight average molecular weight of the binder is 700,000-9,000,000.
  • Vinylidene fluoride polymers with a weight average molecular weight in this range have excellent bonding properties and electrochemical stability.
  • the use of vinylidene fluoride polymers with a weight average molecular weight of 700,000-9 million can further reduce the amount of vinylidene fluoride used, reduce the rigidity of the positive electrode film layer, and increase the flexibility of the electrode, thereby increasing the battery's ultimate compaction density and helping to improve the battery's energy density.
  • the maximum solid content of the positive electrode slurry is not less than 60%, and can be optionally 60%-80%.
  • the fifth aspect of the present application provides a positive electrode plate, which includes a positive electrode film layer, which is prepared by the positive electrode slurry of any embodiment or the positive electrode film layer includes a dispersant, and the dispersant includes the polymer of the first aspect or the polymer prepared by the preparation method of the second aspect.
  • the positive electrode sheet can be folded in half no less than 2 times when the compaction density is 2.6 g/cm 3 , and can be folded 3-6 times.
  • the polymer can not only effectively increase the solid content of the slurry, but also act as a softener, thereby increasing the flexibility of the positive electrode and further improving the safety and electrochemical performance of the battery.
  • the surface density of the positive electrode sheet is not less than 300 mg/1540.25 cm 2 , and may be 300 mg/1540.25 cm 2 -600 mg/1540.25 cm 2 .
  • the polymer can effectively increase the maximum solid content of the slurry, increasing the coating speed by more than 30%. It is especially suitable for high-speed coating and thick coating molding methods. It can effectively solve the problem of easy cracking of the electrode during thick coating, and help to prepare positive electrode sheets with high flexibility and no cracks after winding molding.
  • the positive electrode film layer includes a dispersant, and the dispersant includes a structure shown in Formula I,
  • X comprises a phosphate group or a phosphite group
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment or a polyester segment
  • R 2 comprises an organic segment
  • the organic segment of R 2 comprises at least one of an amide group and an amino group
  • the end group of the polyether segment comprises an aromatic group
  • the positive electrode active material comprises at least one of lithium iron phosphate and its doping materials, lithium manganese iron phosphate and its doping materials, a carbon-coated material of lithium iron phosphate and its doping materials, and a carbon-coated material of lithium manganese iron phosphate and its doping materials
  • the positive electrode active material comprises at least one of lithium manganese iron phosphate and its doping materials, and a carbon-coated material of lithium manganese iron phosphate and its doping materials; based on the
  • the positive electrode film layer has good dispersibility and processability, which is beneficial to improving manufacturing efficiency and battery performance.
  • a sixth aspect of the present application provides a secondary battery, comprising the positive electrode sheet of the fifth aspect.
  • a seventh aspect of the present application provides an electrical device comprising the secondary battery of the sixth aspect.
  • FIG1 is a schematic diagram of a polymer dispersion mechanism according to an embodiment of the present application.
  • FIG2 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG3 is an exploded view of the secondary battery of one embodiment of the present application shown in FIG2 ;
  • FIG4 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG5 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG6 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG5 ;
  • FIG. 7 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • “Scope” disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application are open-ended or closed-ended.
  • the “include” and “comprising” may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • the synthesis of positive electrode active materials tends to be nano-sized and more densely coated with carbon, so that the positive electrode active materials have a larger specific surface area, resulting in more solvents required for effective dispersion during the slurrying process, thereby reducing the solid content of the slurry.
  • the slurry with low solid content needs to extend the drying time during the electrode coating and drying process, resulting in low production efficiency and high energy consumption; at the same time, the slurry with low solid content may cause problems such as edge warping, cracking and floating of the adhesive during the long heating and drying process, which deteriorates the quality of the electrode.
  • the first aspect of the present application provides a polymer comprising a structure shown in formula I,
  • X comprises a phosphate group or a phosphite group
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment or a polyester segment
  • R 2 comprises an organic segment.
  • polymers include, on the one hand, a collection of macromolecules that are chemically uniform but differ in degree of polymerization, molar mass and chain length, prepared by polymerization reactions; on the other hand, they also include derivatives of such macromolecular collections formed by polymerization reactions, i.e., polymers that can be obtained by reactions of functional groups in the above-mentioned macromolecules, such as addition or substitution, and which may be chemically uniform or chemically heterogeneous.
  • the polymer includes a phosphate polymer.
  • the structure of the phosphate polymer is shown in Formula V:
  • the polymer includes a phosphite polymer.
  • the structural formula of the phosphite polymer is shown in V':
  • the polyether segment refers to a polymer segment containing an ether bond (-C-O-C-) in the structural unit.
  • the polyester segment refers to a polymer segment containing an ester group (—COO—) in the structural unit.
  • hydrocarbon groups refer to groups containing carbon and hydrogen atoms, including but not limited to In alkyl, alkenyl, alkynyl.
  • the organic segment can be either a polymerized repeated structural unit or an organic group formed by a small molecule monomer.
  • the dispersion mechanism of the polymer provided in the embodiment of the present application is shown in Figure 1.
  • Polymer 6 includes an anchoring group 61 and a flexible segment 62.
  • the anchoring group 61 at one end of the polymer 6 acts on the surface of the positive electrode active material 7, and the purpose of dispersion is achieved through the steric hindrance effect of the flexible segment 62.
  • the phosphate group or phosphite group in the polymer 6 can be effectively anchored to the surface of the positive electrode active material 7 through intermolecular forces or electrostatic effects, playing the role of the anchoring group 61.
  • the steric hindrance effect of the flexible segment 62 such as the polyether segment and the polyester segment can be effectively exerted on the surface of the positive electrode active material particles, playing the role of blocking the agglomeration of the positive electrode active material 7, thereby increasing the amount of positive electrode active material 7 that can be effectively dispersed in a unit volume of solvent, slowing down the gelation and agglomeration of the slurry during the homogenization process, reducing the viscosity of the slurry, significantly improving the effective solid content of the slurry, reducing the filtration time of the slurry, and improving the forming efficiency and quality of the pole piece.
  • the polymer provided in the embodiment of the present application can make the slurry suitable for thick coating process, which helps to improve the energy density of the battery.
  • the flexible segments such as polyether segments and polyester segments in the polymer have suitable steric hindrance and low glass transition temperature, which can improve the flexibility of the electrode through the movement of the flexible segments, and simultaneously play a role of dispersion and softening.
  • the organic segment of R 2 comprises at least one of an amide group, an amino group, and an aromatic group.
  • an amide group refers to The group includes both primary amides and secondary and tertiary amides.
  • an amino group refers to The group includes both primary amino groups and secondary and tertiary amino groups.
  • aryl refers to an organic group derived from a monocyclic or polycyclic aromatic hydrocarbon by removing a hydrogen atom.
  • aryl includes, but is not limited to, phenyl, naphthyl, benzyl.
  • Aryl can be unsubstituted or substituted with one or more suitable substituents.
  • the aryl group can be monocyclic or polycyclic. In some embodiments, the aryl group contains at least 6, 7, 8, 9 or 10 carbon atoms.
  • the polymer containing the amide group is characterized by infrared absorption spectroscopy, and an absorption peak of the carbonyl group located in the 1900cm -1 to 1650cm -1 band and a medium-intensity double peak absorption peak of the amide group located in the 3500cm -1 to 3100cm -1 band can be observed.
  • the nitrogen-containing groups or aromatic groups in the polymer help to improve the anchoring effect between the polymer and the positive electrode active material, making the polymer particularly suitable for carbon-coated positive electrode active materials, further improving the versatility of the polymer as a dispersant, and more effectively exerting the dispersing effect of the polymer by increasing the anchoring sites of the dispersant, thereby further increasing the maximum solid content of the slurry, improving the quality of electrode molding, and reducing costs and increasing efficiency.
  • the organic segment of R 2 further comprises a C 2-12 hydrocarbon group.
  • C 2-12 hydrocarbon group refers to a straight or branched hydrocarbon chain group consisting only of carbon and hydrogen atoms, with or without unsaturation, having from two to twelve carbon atoms, and attached to the rest of the molecule by at least one single bond.
  • Examples of C 2-12 hydrocarbon groups include, but are not limited to, C 2-12 alkyl, C 2-12 alkylene, C 2-12 alkenyl, C 2-12 alkenylene.
  • C2-12 hydrocarbon groups in the polymer helps to further improve the anchoring effect between the polymer and the carbon-modified positive electrode active material.
  • the hydrocarbon groups can effectively anchor to the carbon on the positive electrode active material, increasing the dispersion of the anchoring sites of the polymer on the positive electrode active material, thereby further improving the application range of the polymer dispersant, increasing the maximum solid content of the slurry, optimizing the quality of electrode forming while reducing costs and increasing efficiency.
  • R 2 comprises a structure as shown in Formula II:
  • R4 and R5 are randomly copolymerized, R4 includes at least one of C2-12 alkylene group and C3-13 amide group, and R5 includes At least one of;
  • R 6 a and R 6 b include at least one of hydrogen and C 1-4 alkyl, 1 ⁇ s ⁇ 6, and 1 ⁇ t ⁇ 10.
  • C 2-12 alkylene refers to a divalent hydrocarbon group having 2 to 12 carbon atoms; including C 2-12 alkylene and C 2-12 alkenylene.
  • C 2-12 alkylene includes, but is not limited to, 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,3-butylene, 1,4-butylene, 2-methyl-1,3-propylene, 1,1-dimethyl-1,2-ethylene, 1,4-pentylene, 1,5-pentylene, 2-methyl-1,4-butylene, 2,2-dimethyl-1,3-propylene, 1,6-hexylene, 2-methyl-1,5 -pentylene, 3-methyl-1,5-pentylene, 2,3-dimethyl-1,4-butylene, 1,7-heptylene, 2-methyl-1,6-hexylene, 3-methyl-1,6-hexylene, 2-ethyl-1,5-pentylene, 3-ethyl-1,5-pentylene, 2,3
  • the C2-12 alkenylene group is a divalent hydrocarbon group containing at least one double bond.
  • the C2-12 alkenylene group includes vinylene, propenylene, 1-methylvinylene, 1-butenylene, 2-butenylene, 1-methylpropenylene, 2-methylpropenylene, 1-pentenylene, 2-pentenylene, 1-methyl-1-butenylene, 1-methyl-2-butenylene, 1-hexenylene, 2-hexenylene, 3-hexenylene, 1-methyl-1-pentenylene, 1-methyl-2-pentenylene, 1-methyl-3-pentenylene, 1,4-dimethyl-1-butenylene, 1,4-dimethyl-2-butenylene, 1-heptenylene, 2-heptenylene, 3-heptenylene, 1-octenylene, 2-octenylene, 1-octenylene, 2-octenylene, 3 ... Oxenyl, 3-octenylene.
  • the C 3-13 amide group comprises the following group:
  • x is 2 to 12, and can be selected from 2 to 5.
  • x is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12.
  • the C 1-4 alkyl group includes at least one of a methyl group, an ethyl group, a propyl group, an isopropyl group, a 2-methyl-1-propyl group, and a 2-methyl-2-propyl group.
  • s is any one of 1, 2, 3, 4, 5, and 6.
  • t is any one of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10.
  • q1, q2, q3, q4 are each independently selected from 0, 1, 2, 3 or 4.
  • the organic chain segments of the above structure include nitrogen-containing groups and alkylene groups, which can play an anchoring role more effectively, enhance the dispersion effect of the polymer, and effectively increase the solid content of the slurry.
  • R 2 comprises a structure shown in Formula III
  • R 6 includes C 2-12 alkylene group
  • R 7 includes At least one of; wherein, q5 and q6 each independently include any integer between 0-4, 1 ⁇ n ⁇ 6.
  • q5 and q6 each independently include 0, 1, 2, 3 or 4.
  • n is any one of 1, 2, 3, 4, 5, and 6.
  • the organic chain segments of the above structure can more effectively play an anchoring role through the alternating arrangement of nitrogen-containing groups and alkylene groups, enhance the dispersion effect of the polymer, and effectively increase the solid content of the slurry.
  • the terminal group of R 2 comprises at least one of -C(O)-NH 2 , -CH 2 -NH 2 .
  • the polymer whose terminal groups include -C(O)-NH 2 and -CH 2 -NH 2 can play a more effective dispersing role, increase the maximum solid content of the slurry, and thus improve the molding quality and efficiency of the pole piece.
  • At least one of R 1 and R 3 comprises a polyether segment. In some embodiments, both R 1 and R 3 comprise a polyether segment.
  • the polymer comprising the polyether segment is characterized by infrared absorption spectroscopy, and the ether bond absorption peak can be observed to be located in the 1250-1100 cm -1 band.
  • R 2 includes at least one of H and aryl.
  • one of R 1 and R 3 comprises a polyether segment, and the other comprises a C 1-4 alkyl group.
  • both R 1 and R 3 include a polyether segment.
  • R 1 and R 3 both include polyether segments. Compared with one of R 1 and R 3 including a polyether segment and the other including a C 1-4 alkyl group, the polymer further optimizes the filterability of the slurry and further improves the flexibility of the electrode.
  • At least one of R 1 and R 3 comprises a polyether segment represented by Formula IV
  • EO represents -CH 2 -CH 2 -O-
  • PO represents -CH(CH 3 )-CH 2 -O-, 4 ⁇ m1 ⁇ 50, 4 ⁇ n1 ⁇ 50.
  • the polyether segment is a block copolymer segment. In some embodiments, the polyether segment is a random copolymer segment.
  • m1 and n1 can be independently selected from 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50 or any value therebetween.
  • the polyether segment with the above structure has suitable steric hindrance and low glass transition temperature, which can more effectively reduce the order of the binder crystal in the positive electrode slurry and
  • the glass transition temperature can reduce the crystallinity of the binder, improve the flexibility of the pole piece, and improve the uniformity and flexibility of the pole piece through dispersion and flexibility enhancement, thereby improving the safety performance and ultimate compaction density of the battery, increasing the loading capacity of the positive electrode active material of the battery, and helping to further improve the energy density of the battery.
  • the end groups of the polyether segments include aromatic groups.
  • the aromatic group has excellent compatibility with the carbon layer on the surface of the positive electrode active material, which helps to further improve the anchoring effect between the polymer and the carbon-modified positive electrode active material.
  • the aromatic group and the carbon on the positive electrode active material can be effectively anchored to increase the dispersion of the anchoring sites of the polymer on the positive electrode active material, thereby further improving the application range of the polymer dispersant, increasing the maximum solid content of the slurry, optimizing the quality of electrode molding, and reducing costs and increasing efficiency.
  • X comprises a phosphate group.
  • Phosphate polymers can more effectively increase the solid content of the slurry, shorten the filtration time, and improve the flexibility of the electrode; and phosphate polymers have better stability, and can effectively improve the battery's cycle capacity retention rate on the basis of improving the slurry's dispersibility.
  • the polymer includes at least one of the following polymers:
  • R 1 and R 3 comprises a block copolymer polyether segment represented by formula IV
  • EO represents -CH 2 -CH 2 -O-
  • PO represents -CH(CH 3 )-CH 2 -O-, 4 ⁇ m1 ⁇ 15, 4 ⁇ n1 ⁇ 15.
  • R 6 and R 4 each independently include at least one of C 4-8 alkylene and C 4-8 alkenylene.
  • R 6 and R 4 each independently include -(CH 2 ) 4 -, -(CH 2 ) 5 -, -(CH 2 ) 6 -, -(CH 2 ) 7 -, -(CH 2 ) 8 -, At least one of the groups.
  • the end groups of the polyether segments include phenyl groups.
  • the polymer is represented by the following formula:
  • R2 comprises at least one of hydrogen, aryl, substituted or unsubstituted alkyl, and an organic segment containing an amino group or an amide group
  • at least one of R1 and R3 comprises a block copolymer polyether segment represented by formula IV
  • EO represents -CH 2 -CH 2 -O-
  • PO represents -CH(CH 3 )-CH 2 -O-
  • the terminal group of the polyether segment includes phenyl.
  • the weight average molecular weight of the polymer is 1,000-10,000. In some embodiments, the weight average molecular weight of the polymer is 2,000-5,000.
  • the weight average molecular weight has a meaning known in the art and can be measured by methods known in the art. As an example, the weight average molecular weight can be measured by gel chromatography.
  • the weight average molecular weight of the polymer is 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, or any value therebetween.
  • the polymer with a weight average molecular weight within the above range can not only play an excellent dispersibility and further increase the solid content of the slurry, but also make the slurry have excellent flow properties, reduce the coating time, and improve the uniformity and speed of coating.
  • the polymer with a weight average molecular weight of 2000-5000 can play a more effective dispersing role, increase the maximum solid content of the slurry, and shorten the filtration time.
  • the second aspect of the present application provides a method for preparing a polymer, the preparation method comprising the following steps:
  • the compound represented by Formula VI is reacted with R 3 OH, R 1 OH, water, and a polymerizable monomer containing an unsaturated bond to prepare a polymer having a structure represented by Formula I.
  • X comprises a phosphate group or a phosphite group
  • X 1 , X 2 , and X 3 all comprise halogen
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment or a polyester segment
  • R 2 comprises an organic segment.
  • the halogen includes at least one of fluorine, chlorine, bromine and iodine.
  • phosphorus and oxygen in Formula VI are connected by a double bond, and X in Formula I It is a phosphate group.
  • Formula VI does not include oxygen and X in Formula I is a phosphite group.
  • Formula VI includes POCl 3 or PCl 3 .
  • the preparation method comprises the following steps:
  • the intermediate product is subjected to a second reaction with a polymerization monomer containing at least one of an amide containing an unsaturated bond and an amine containing an unsaturated bond to prepare the polymer.
  • the first reaction specifically comprises:
  • R 3 OH is added dropwise to the compound represented by Formula VI under stirring, the reaction temperature is kept below 20°C, the temperature is raised to 40-50°C after stirring for 6-7 hours, water is added, and the reaction is carried out at 50-60°C for 3-4 hours to obtain the first intermediate product represented by Formula A.
  • the molar ratio of R 3 OH added during the reaction to the compound represented by Formula VI is 1.2-1.5, wherein R 3 includes C 1-4 alkyl,
  • the first reaction further comprises:
  • the polyether and the first intermediate product are reacted at 100° C.-120° C. for 4 h-7 h to generate an intermediate product represented by formula VII, wherein R 1 comprises a polyether segment.
  • the second reaction specifically comprises the following steps:
  • the intermediate product undergoes an addition reaction with at least one of an amide containing an unsaturated bond and an amine containing an unsaturated bond, and then undergoes a substitution reaction with a halogen-substituted organic alcohol;
  • the polymer is prepared by cycling the addition reaction and substitution reaction for multiple times;
  • R 2 comprises the structure shown in formula III
  • R 6 includes C 2-12 hydrocarbon group
  • R 7 includes At least one of; wherein, q5 and q6 each independently include any integer between 0-4, 1 ⁇ n ⁇ 6.
  • An addition reaction is a reaction in which the ⁇ bond in a double bond is broken to form two single bonds.
  • Substitution reaction refers to a type of chemical reaction in which an atom or group replaces a certain atom or group in an organic molecule and takes its place.
  • the preparation method further comprises the following steps:
  • the intermediate product is reacted with (i) at least one of an amide containing an unsaturated bond and an amine containing an unsaturated bond, and (ii) at least one of a hydrocarbon monomer containing an unsaturated bond and a cyclic amide monomer to prepare the polymer, wherein R 2 comprises a structure shown in Formula II
  • R4 and R5 are randomly copolymerized, R4 includes at least one of a C2-12 hydrocarbon group and a C3-13 amide group, and R5 includes At least one of;
  • R 6 a and R 6 b include at least one of hydrogen and C 1-4 alkyl, 1 ⁇ s ⁇ 6, and 1 ⁇ t ⁇ 10.
  • the hydrocarbon monomer containing an unsaturated bond comprises at least one of an olefin monomer, an alkyne monomer, and a cyclic alkane.
  • a cyclic amide monomer refers to a cyclic monomer including an amide bond.
  • the third reaction specifically comprises mixing the intermediate product with After at least one of the hydrocarbon monomers and cyclic amide monomers with unsaturated bonds reacts for a period of time, at least one of the amides and amines containing unsaturated bonds is added to cause copolymerization.
  • the preparation method further comprises the following steps:
  • the polymer having a terminal group of hydroxyl group is subjected to a capping reaction with an unsaturated monomer containing an amide group or an amino group to prepare a polymer having a terminal group containing an amide group or an amino group.
  • the present application provides a method for preparing a polymer, the preparation method comprising:
  • the compound represented by Formula VI is reacted with raw materials including R 3 OH and R 1 OH to prepare a polymer having a structure represented by Formula I.
  • X comprises a phosphate group or a phosphite group
  • X 1 , X 2 , and X 3 all comprise halogen
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment, and the terminal group of at least one of the polyether segments comprises an aromatic group
  • R 2 comprises an organic segment.
  • the monomer represented by Formula VI is reacted with R 1 OH and R 3 OH in an inert, alkaline environment, and then water or phenol is added to react to obtain a polymer.
  • the polymer containing a hydroxyl group in R2 is further subjected to a second reaction with a polymerizable monomer containing at least one of an amide containing an unsaturated bond and an amine containing an unsaturated bond to prepare a polymer containing nitrogen in R2.
  • the polymer according to any embodiment of the present application and the polymer prepared by the preparation method according to any embodiment of the present application are used as a dispersant.
  • the polymer of any embodiment of the present application and the polymer prepared by the preparation method of any embodiment of the present application are used as a secondary battery electrode slurry. Dispersant.
  • the polymer according to any embodiment of the present application and the polymer prepared by the preparation method according to any embodiment of the present application are used as a dispersant in a positive electrode slurry of a secondary battery.
  • a third aspect of the present application provides a positive electrode slurry, wherein the positive electrode slurry includes a dispersant, and the dispersant includes a polymer in any embodiment or a polymer prepared by a preparation method in any embodiment.
  • the positive electrode slurry has a high solid content, which helps to improve the molding efficiency and molding quality of the positive electrode film layer, and improve the electrochemical performance and processing efficiency of the battery.
  • the positive electrode slurry includes a positive electrode active material, and the positive electrode active material includes at least one of a lithium-containing phosphate and a carbon-modified material thereof.
  • the lithium-containing phosphate includes at least one of lithium iron phosphate and its doping materials, lithium iron manganese phosphate and its doping materials.
  • the doping material includes a doping material at any site, which can be lithium doping, phosphorus doping, manganese doping, and iron doping.
  • the carbon-modified material includes at least one of a carbon-coated material and a carbon-doped material.
  • the positive electrode active material includes at least one of lithium iron phosphate and its doped materials, lithium iron manganese phosphate and its doped materials, carbon-coated materials of lithium iron phosphate and its doped materials, and carbon-coated materials of lithium iron manganese phosphate and its doped materials.
  • the polymer is negatively charged and can further strengthen the mutual anchoring with the weakly acidic lithium-containing phosphate through electrostatic interaction, thereby improving the dispersion effect of the polymer on the lithium-containing phosphate.
  • the lithium-containing phosphate has poor conductivity. Therefore, in the preparation process of positive electrode active materials, the method of sintering organic substances such as glucose and sucrose to coat the carbon layer is often used to improve its conductivity.
  • the polymer also has groups that can be mutually anchored with the carbon coating layer, and also has an excellent dispersion effect on the carbon-modified lithium-containing phosphate, which can further improve the dispersibility of its slurry, thereby increasing the maximum solid content of the slurry.
  • the positive electrode active material includes a core and a carbon coating.
  • a layer is formed, wherein the carbon coating layer covers at least a portion of the surface of the inner core, wherein the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer is not less than 0.2.
  • the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer is not less than not less than 0.5.
  • the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer is not less than not less than not less than 0.8.
  • the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer can be selected as 0.2, 0.3, 0.4, 0.5, 0.6, 0,7, 0.8, 0.9 or any range therebetween.
  • the carbon structure and characteristics of the carbon coating layer can be measured by methods known in the art. As an example, it can be measured by Raman spectroscopy, specifically: first measure the Raman spectrum of the positive active material, and obtain Ig/Id (where Id is the peak intensity of sp 3 hybridized carbon atoms, Ig is the peak intensity of sp 2 hybridized carbon atoms, and the peak intensity ratio is the ratio of the peak height of sp 2 hybridized carbon atoms to the peak height of sp 3 hybridized carbon atoms) by peak separation of the energy spectrum of the Raman test, thereby obtaining the molar ratio of sp 2 hybridized carbon to sp 3 hybridized carbon.
  • Id is the peak intensity of sp 3 hybridized carbon atoms
  • Ig is the peak intensity of sp 2 hybridized carbon atoms
  • the peak intensity ratio is the ratio of the peak height of sp 2 hybridized carbon atoms to the peak height of sp 3 hybridized carbon atoms
  • the molar ratio of sp 2 hybridized carbon atoms to sp 3 hybridized carbon atoms in the carbon coating layer of the positive active material is not particularly limited.
  • the molar ratio of sp 2 hybridized carbon atoms to sp 3 hybridized carbon atoms in the carbon coating layer may be not less than 0.5.
  • the molar ratio of sp 2 hybridized carbon atoms to sp 3 hybridized carbon atoms in the carbon coating layer may be not less than 0.8.
  • the carbon coating layer on the surface of the inner core has a higher degree of graphitization and a denser structure, which can not only reduce the water absorption of the carbon coating layer, but also enable the carbon coating layer to achieve good conductivity, thereby ensuring the passage of lithium ions and being beneficial to improving the cycle performance and safety performance of the positive electrode active material.
  • the core includes a phosphate; in some embodiments, the phosphate includes at least one of lithium manganese phosphate, lithium iron phosphate, lithium manganese iron phosphate, and doped materials thereof.
  • the formation of a carbon coating layer on the surface of the core can improve the conductivity of the positive electrode active material.
  • the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer on the surface of the core is not less than 0.5, the structure of the carbon coating layer of the positive electrode active material is highly ordered, and the pore structure of the carbon coating layer has a high density and a small pore size distribution range, which is very important in the production process of the battery.
  • it is difficult for external moisture to enter the pores of the carbon coating layer thereby effectively reducing the water absorption and water storage properties of the positive electrode active material, improving the battery safety and cycle performance, effectively saving energy consumption in the drying process, and significantly reducing production costs.
  • the carbon coating layer with a molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms of not less than 0.5 has a high degree of graphitization, which makes the positive electrode active material easy to agglomerate and difficult to effectively disperse during the pulping process.
  • the dispersant provided in the embodiment of the present application and the carbon coating layer with a high degree of graphitization have rich anchoring groups, which are particularly suitable for the dispersion of positive electrode active materials with a high degree of graphitization of the coating layer. The combination of the two can simultaneously improve the performance and processing performance of the battery.
  • the inner core includes Li1 + xMn1-yAyP1 - zRzO4 , x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, A includes one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and R includes one or more elements of B (boron), S, Si and N.
  • the manganese-site doping element A selected from the above elements helps to reduce the lattice change rate of lithium manganese phosphate in the process of lithium insertion and extraction, improves the structural stability of the positive electrode active material, greatly reduces the dissolution of manganese and reduces the oxygen activity on the surface of the particles; the phosphorus-site doping element R selected from the above elements also helps to change the difficulty of the Mn-O bond length change, thereby improving electronic conductivity and reducing the lithium ion migration barrier, promoting lithium ion migration, and improving the rate performance of the secondary battery.
  • the above-mentioned limitation on the numerical range of x, y, z or m is not only a limitation on the stoichiometric number of each element as the site, but also a limitation on the sum of the stoichiometric numbers of each element as the site.
  • the type of the core is not particularly limited.
  • the core may include Li 1+x C m Mn 1-y A y P 1-z R z O 4-n D n , and the size of x is affected by the valence of A and R and the size of y and z to ensure that the entire system is electrically neutral. If the value of x is too small, the lithium content of the entire core system will be reduced, affecting the gram capacity of the material.
  • x is any value in the range of -0.100 to 0.100
  • y is any value in the range of 0.001 to 0.500
  • z is any value in the range of 0.001 to 0.100
  • n is any value in the range of 0.001 to 0.1
  • m is any value in the range of 0.9 to 1.1.
  • 1+x is selected from the range of 0.9 to 1.1, for example, 0.97, 0.977, 0.984, 0.988, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, 1.01
  • x is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005
  • y is selected from the range of 0.001 to 0.5, for example, 0.001 , 0.005, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.34, 0.345, 0.349, 0.35, 0.4
  • z is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1
  • n is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1, and the positive electrode active material is electrically neutral.
  • C includes one or more elements of Zn, Al, Na, K, Mg, Nb, Mo and W
  • A includes one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge
  • R includes one or more elements of B (boron), S, Si and N
  • D includes one or more elements of S, F, Cl and Br.
  • the thickness of the carbon coating layer is no greater than 15 nm. In some embodiments, the thickness of the carbon coating layer is no greater than 10 nm. In some embodiments, the thickness of the carbon coating layer is 4 nm-8 nm.
  • the thickness of the carbon coating layer may be 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or any range therebetween.
  • the thickness of the carbon coating can be tested as follows: a thin slice of about 100 nm thick is cut from the middle of a single particle of the positive electrode active material by FIB, and then the slice is tested by transmission electron microscopy (TEM) to obtain the original TEM test image and save the original image format (xx.dm3).
  • TEM transmission electron microscopy
  • the original image obtained by the above TEM test is opened in the Digital Micrograph software, and the carbon coating is identified by the lattice spacing and angle information, and the thickness of the carbon coating is measured. The thickness of the selected particle is measured at three positions and the average value is taken.
  • the carbon coating layer within the above thickness range can form a thinner carbon coating layer on the surface of the inner core, which can effectively improve the conductivity of the positive electrode active material and improve the compaction performance when the positive electrode active material is used to prepare a battery pole piece.
  • the positive electrode active material is prepared by the following method:
  • Providing an inner core forming a carbon coating layer on at least a portion of the surface of the inner core, wherein the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer is not less than 0.2, and optionally not less than 0.5.
  • forming a carbon coating layer on at least a portion of the surface of the inner core includes: forming a pre-carbon coating layer on the inner core surface through a carbon source to obtain a pre-coated positive electrode active material; sintering the pre-coated positive electrode active material to form the carbon coating layer to obtain the positive electrode active material, and the carbon source includes a first carbon source and a second carbon source.
  • a pre-carbon coating layer is formed on the surface of the inner core to obtain a pre-coated positive electrode active material.
  • the method for forming the pre-carbon coating layer on the inner core surface is not particularly limited.
  • the carbon source and the inner core can be placed in the same reaction container, and the carbon source can be reacted on the inner core surface by hydrothermal treatment to form a carbon coating layer on the inner core surface.
  • the carbon source and the inner core can also be placed in a ball milling device, such as a sand mill, and the carbon source can be mechanically mixed to form a carbon coating layer on the inner core surface.
  • the carbon source includes a first carbon source and a second carbon source, and the first carbon source includes at least one of polyvinyl alcohol, polyethylene glycol, and citric acid; the second carbon source includes at least one of starch, sucrose, and glucose.
  • the molecular weight of the first carbon source is not less than 1000. In other embodiments, the molecular weight of the first carbon source can be 2000-5000.
  • a pre-carbon coating layer can be formed on the inner core surface by ball milling. The carbon coating layer is uniformly distributed and has a relatively uniform thickness, which is conducive to forming a dense and uniform carbon coating layer pore structure after sintering.
  • the second carbon source may include at least one of starch, sucrose and glucose. In some embodiments, the second carbon source may be glucose.
  • the pre-coated positive electrode active material is sintered under an inert gas atmosphere. In some embodiments, the pre-coated positive electrode active material is sintered to obtain the positive electrode active material.
  • the sintering treatment should be carried out under an inert atmosphere to avoid oxidation reaction of the carbon source so that a carbon coating layer with a high degree of graphitization cannot be obtained.
  • the type of inert gas is not particularly limited.
  • the inert gas may include at least one of nitrogen and helium.
  • the conditions of the sintering treatment are not particularly limited. For example, the temperature of the sintering treatment may be 650°C-800°C, and the time of the sintering treatment may be 6h-12h.
  • a carbon coating layer with a high degree of graphitization can be formed on the surface of the inner core.
  • the degree of graphitization of the carbon coating layer can be effectively controlled by controlling the highest sintering treatment of the sintering treatment, and the carbon coating layer has a dense pore structure and better conductivity.
  • forming a carbon coating layer on at least a portion of the surface of the inner core includes: mixing the inner core with a first carbon source and obtaining a first coated positive electrode active material through a first sintering treatment; mixing the first coated positive electrode active material with a second carbon source and obtaining the positive electrode active material through a second sintering treatment.
  • the temperature of the first sintering process is 350°C-800°C, and the time of the first sintering process is 6h-12h. In some embodiments, the temperature of the second sintering process is 650°C-850°C, and the time of the second sintering process is 6h-24h.
  • the mass content of the polymer is 0.1%-2.0%. In some embodiments, based on the total mass of dry materials in the positive electrode slurry, the mass content of the polymer is 0.2%-1.0%.
  • the mass content of the polymer may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0% or any value therebetween.
  • Polymers can not only play an effective dispersing role, but also take into account the volume energy density of the battery, and will not have a serious negative impact on the electrochemical performance of the battery.
  • the positive electrode slurry includes a binder, and the binder includes a vinylidene fluoride polymer with a weight average molecular weight of not less than 300,000. In some embodiments, the weight average molecular weight of the binder is 700,000-9,000,000.
  • the vinylidene fluoride polymer is a vinylidene fluoride homopolymer.
  • the vinylidene fluoride polymer is a vinylidene fluoride copolymer.
  • the weight average molecular weight has a well-known meaning in the art and can be measured by any well-known method.
  • the weight average molecular weight of the binder is characterized by gel chromatography.
  • the weight average molecular weight of the binder can be selected to be 700,000, 1,000,000, 2,000,000, 3,000,000, 4,000,000, 5,000,000, 6,000,000, 7,000,000, 8,000,000, 9,000,000, or any value therebetween.
  • Vinylidene fluoride polymers with a weight average molecular weight in this range have excellent bonding properties and electrochemical stability.
  • the use of vinylidene fluoride polymers with a weight average molecular weight of 700,000-9 million can further reduce the amount of vinylidene fluoride used, reduce the rigidity of the positive electrode film layer, and increase the flexibility of the electrode, thereby increasing the battery's ultimate compaction density and helping to improve the battery's energy density.
  • the maximum solid content of the positive electrode slurry is not less than 60%. In some embodiments, the maximum solid content of the positive electrode slurry is 60%-80%.
  • the maximum solid content of the positive electrode slurry refers to the maximum solid content of the slurry that meets the shipping viscosity between 4000 and 35000mpa.s and does not gel after the positive electrode slurry is left to stand for 24 hours.
  • the maximum solid content of the positive electrode slurry may be 60%, 65%, 70%, 75%, 80% or any value therebetween.
  • the solid content and flexibility of the slurry are effectively increased, and the flexibility and molding efficiency of the electrode are improved.
  • the present application also provides a positive electrode plate, which includes a positive electrode film layer, which is prepared by the positive electrode slurry of any embodiment or the positive electrode film layer includes a dispersant, and the dispersant includes a polymer of any embodiment or a polymer prepared by the preparation method of any embodiment.
  • the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode sheet can be folded for no less than 2 times when the compaction density is 2.6 g/cm 3. In some embodiments, the positive electrode sheet can be folded for 3-6 times when the compaction density is 2.6 g/cm 3 .
  • the number of times the positive electrode sheet can be folded when the compaction density is 2.6g/ cm3 can be used to characterize the flexibility of the electrode sheet and can be measured by any known method. As an example, take a defect-free positive electrode sheet with a compaction density of 2.6g/ cm3 , cut it into a sample with a length*width of 25cm*4cm in the longitudinal direction, and the number of samples is ⁇ 4 sheets. After pre-folding it in the longitudinal direction (25cm direction), place the membrane on the test platform and roll it once with a 2kg cylindrical roller. If it is light-transmitting, the number of brittle light-transmitting times is 1. If it is not light-transmitting, repeat the reverse folding and rolling. Observe the crease against the light to see if it is light-transmitting or broken, record the actual number of folds, test 4 times, and take the average as the test result.
  • the positive electrode sheet can be folded 2 times, 3 times, 4 times, 5 times or 6 times when the compaction density is 2.6 g/cm 3 .
  • the polymer can not only effectively increase the solid content of the slurry, but also act as a softener to increase the flexibility of the positive electrode sheet, further improving the safety performance and electrical conductivity of the battery. Chemical properties.
  • the surface density of the positive electrode sheet is not less than 300 mg/1540.25 cm 2 . In some embodiments, the surface density of the positive electrode sheet is 300 mg/1540.25 cm 2 -600 mg/1540.25 cm 2 .
  • the surface density of the positive electrode sheet is 300 mg/1540.25 cm 2 , 400 mg/1540.25 cm 2 , 450 mg/1540.25 cm 2 , 500 mg/1540.25 cm 2 , 600 mg/1540.25 cm 2 or any value therebetween.
  • the surface density of the electrode sheet has a known meaning and can be measured by any known method.
  • the positive electrode plate comprises lithium iron phosphate, and the surface density of the positive electrode plate is not less than 360 mg/1540.25 cm 2 . In some embodiments, the surface density of the positive electrode plate is 360 mg/1540.25 cm 2 -600 mg/1540.25 cm 2 .
  • the positive electrode plate comprises lithium iron manganese phosphate, and the surface density of the positive electrode plate is not less than 300 mg/1540.25 cm 2 . In some embodiments, the surface density of the positive electrode plate is 300 mg/1540.25 cm 2 -600 mg/1540.25 cm 2 .
  • the polymer can effectively increase the maximum solid content of the slurry, increasing the coating speed by more than 30%. It is especially suitable for high-speed coating and thick coating molding methods. It can effectively solve the problem of easy cracking of the electrode during thick coating, and help to prepare positive electrode sheets with high flexibility and no cracks after winding molding.
  • the positive electrode film layer includes a dispersant, and the dispersant includes a structure shown in Formula I,
  • X comprises a phosphate group or a phosphite group
  • R 1 and R 3 each independently comprise at least one of a polyether segment, a polyester segment, hydrogen, and a hydrocarbon group, and at least one of R 1 and R 3 comprises a polyether segment or a polyester segment
  • R 2 comprises an organic segment; optionally, the organic segment of R 2 comprises at least one of an amide group and an amino group; optionally, the end group of the polyether segment comprises an aromatic group;
  • the positive electrode active material comprises lithium iron phosphate and its doping materials, lithium manganese iron phosphate and its doping materials, a carbon-coated material of lithium iron phosphate and its doping materials, and manganese phosphate At least one of carbon-coated materials of lithium iron and its doped materials; optionally, the positive electrode active material includes lithium iron manganese phosphate and its doped materials, lithium iron manganese phosphate and its doped materials. At least one of carbon-coated materials, based on the total mass of the
  • the positive electrode film layer has good dispersibility and processability, which is conducive to the simultaneous improvement of manufacturing efficiency and battery performance.
  • the positive electrode film layer may also optionally include 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 by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and the dispersant are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may be a negative electrode active material for a battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based Materials and lithium titanate, etc.
  • the silicon-based material can 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 can be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide ... At least one of lithium, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorobisoxalatophosphate and lithium tetrafluorooxalatophosphate.
  • the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the secondary battery further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • Another aspect of the present application provides a secondary battery, the secondary battery comprising the positive electrode sheet of any embodiment.
  • FIG2 is a secondary battery 5 of a square structure as an example.
  • the secondary battery may also be a sodium ion battery, a magnesium ion battery, or a potassium ion battery.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries may be assembled into a battery module.
  • the number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG4 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.
  • the battery modules described above may also be assembled into a battery pack.
  • the battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, wherein the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 may be arranged in the battery box in any manner.
  • an electric device comprising at least one of a secondary battery of any embodiment, a battery module of any embodiment, or a battery pack of any embodiment.
  • the electrical device includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • Fig. 7 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or a battery module may be used.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • POCl 3 is added to a four-necked flask equipped with a thermometer, a stirrer and a hydrogen chloride gas collecting device, and R 3 OH is added dropwise under stirring, the reaction temperature is kept below 20°C, and the temperature is raised to 40-50°C after stirring for 20 minutes, wherein n(POCl 3 ):n(R 3 -OH) is 1.2-1.5, and after reacting for 6-7 hours, a certain amount of distilled water is added dropwise to the system, and the reaction is carried out at 55°C for 3.5 hours to prepare the first intermediate product.
  • the yield of the first intermediate product can be ⁇ 95% by controlling the reaction parameters, wherein R 3 is -CH 2 CH 3 .
  • the second intermediate product was subjected to addition reaction with acrylamide at room temperature for 12 hours, and then HO(CH 2 ) 4 Cl was added to carry out substitution reaction at room temperature under alkaline conditions for 6 hours, and the above addition reaction and substitution reaction were cycled once to prepare the product represented by formula X in which R 6 is -(CH 2 ) 4 - and n is 2.
  • the weight average molecular weight of the polymer is 3109.
  • the positive electrode active material carbon-coated lithium iron phosphate (LFP@C), conductive agent carbon black (SP), binder polyvinylidene fluoride (PVDF), and dispersant (the above polymer) are added to N-methylpyrrolidone (NMP) at a mass ratio of 96.5:2:1:0.5, the mass fraction of the dispersant is 0.5% of the dry material in the slurry, and the weight average molecular weight of PVDF is 700,000.
  • NMP N-methylpyrrolidone
  • the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer of lithium iron phosphate is 0.271.
  • the positive electrode slurry is evenly coated on the two surfaces of the aluminum foil positive electrode current collector, and then dried to obtain a film layer; thereafter, the film is cold pressed and cut to obtain a positive electrode sheet, and the surface density of the positive electrode sheet is 450 mg/1540.25 mm 2 .
  • the negative electrode active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium hydroxymethyl cellulose (CMC) are dissolved in the solvent deionized water in a weight ratio of 96:2:1:1, and mixed evenly to prepare the negative electrode slurry; the negative electrode slurry is evenly coated on the two surfaces of the negative electrode collector copper foil for multiple times, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.
  • Polypropylene film is used as the isolation film.
  • the positive electrode sheet, separator, and negative electrode sheet prepared in Example 1 are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role, and then wound to obtain a bare cell, and the bare cell is welded with a pole ear, and the bare cell is placed in an aluminum shell, and baked at 80°C to remove water, and then the electrolyte is injected and sealed to obtain an uncharged battery.
  • the uncharged battery is then subjected to the processes of static, hot and cold pressing, formation, shaping, and capacity testing in sequence to obtain the lithium-ion battery product of Example 1.
  • the preparation method is similar to that of Example 1, except that the type of dispersant is changed.
  • the first two steps of the dispersant synthesis process are consistent with those of Example 1.
  • the nitrogen-containing monomer added in the third step is 3-amino-1-propylene.
  • the dispersant structural formula is as follows, wherein R 1 , R 3 , R 6 , and n are consistent with those of Example 1.
  • the preparation method is similar to that of Example 1, except that the type of dispersant is changed.
  • the first two steps of the dispersant synthesis process are consistent with those of Example 1, and the preparation process of the third step polymer is as follows:
  • Butadiene was added to the second intermediate product and reacted at 100° C. for 0.5 h, and then acrylamide was added. The reaction was carried out at 110° C. in an alkaline environment for 6 h to obtain a polymer.
  • the reaction schematic diagram is shown in the figure below, wherein R 1 and R 3 are consistent with those in Example 1, s is 3, t is 3, and the structural unit derived from butadiene and the structural unit derived from acrylamide are random copolymers.
  • the preparation method is similar to that of Example 1, except that the type of dispersant is changed.
  • the first two steps of the dispersant synthesis process are consistent with those of Example 1, and the preparation process of the third step polymer is as follows:
  • Butadiene was added to the second intermediate product, and the mixture was reacted at 100° C. for 0.5 h. Then, 3-amino-1-propylene was added, and the mixture was reacted in an alkaline environment at 110° C. for 6 h to obtain a polymer.
  • the reaction schematic diagram is shown in the figure below, wherein R 1 and R 3 are consistent with those in Example 1, s is 3, t is 3, and the structural unit derived from butadiene and the structural unit derived from 3-amino-1-propylene are random copolymers.
  • the preparation method is similar to that of Example 1, except that the type of dispersant is changed.
  • the first two steps of the dispersant synthesis process are consistent with those of Example 1.
  • the preparation process of the polymer is as follows:
  • Butadiene was added to the second intermediate product and reacted at 100° C. for 6.5 h in an alkaline environment to obtain a polymer.
  • the reaction schematic diagram is shown in the figure below, wherein R 1 and R 3 are consistent with those in Example 1, s+t is 6,
  • the preparation method is similar to that of Example 1, except that the dispersant is different.
  • the preparation method of the dispersant is to further react the product of Example 1 with 3-amino-1-propylene to prepare a polymer having an amino terminal group, the structure of which is shown below, wherein R 1 , R 3 , R 6 , and n are the same as those in Example 1. Be consistent,
  • Example 1 The preparation method is similar to that of Example 1, except that the product of Example 1 is further reacted with acrylamide to prepare a polymer with an amide terminal group.
  • the structure is shown below, wherein R 1 , R 3 , R 6 , and n are the same as those in Example 1.
  • Example 8-15 The preparation method of Examples 8-15 is similar to that of Example 7, except that in Examples 8-11, the weight average molecular weight of the polymer is regulated by adjusting the degree of polymerization of the polyether segment, and in Examples 12-15, the amount of dispersant added is adjusted to keep the total mass of the positive electrode film layer unchanged. As the mass content of the dispersant changes, the mass percentage of the positive electrode active material is adjusted accordingly. For specific parameters, see Table 1.
  • Example 16 The preparation method of Example 16 is similar to that of Example 3.
  • Example 17 The preparation method of Example 17 is basically the same as that of Example 7, except that R1 is prepared by The monomers added in the process are all ethylene oxide, so the polyether chain segment is polyethylene oxide.
  • the preparation method of Example 18 is basically the same as that of Example 7, except that the anchoring group of the dispersant in Example 7 is a phosphite group.
  • the preparation method is basically the same as that of the dispersant in Example 7, except that PCl 3 is not initially input during the preparation process.
  • the structure of the dispersant is shown below, wherein R 1 , R 3 , R 6 , and n are the same as those in Example 1.
  • Example 19 The preparation method of Example 19 is basically the same as that of Example 7, except that in Example 19, the R3 group is the same as the R1 group, both are polyether segments, wherein n2 is 12 and m2 is 13.
  • the preparation process of the dispersant is basically the same as that of Example 7, except that the preparation process of the second intermediate product is different, as follows:
  • the product was further reacted in the same manner as in Example 7 to join the R2 group to form a phosphorus-containing polymer as a dispersant.
  • Example 20 The preparation method of Example 20 is basically the same as that of Example 7, except that the weight average molecular weight of the binder PVDF is 300,000; the ratio of the positive electrode active material carbon-coated lithium iron phosphate (LFP@C), the conductive agent carbon black (SP), the binder polyvinylidene fluoride (PVDF), and the dispersant is 96:2:1.5:0.5.
  • the weight average molecular weight of the binder PVDF is 300,000; the ratio of the positive electrode active material carbon-coated lithium iron phosphate (LFP@C), the conductive agent carbon black (SP), the binder polyvinylidene fluoride (PVDF), and the dispersant is 96:2:1.5:0.5.
  • Example 21 the It acts as a dispersant directly without joining the R2 group.
  • Example 22 The preparation method of Example 22 is basically the same as that of Example 19, except that the initial input in the synthesis process of the dispersant polyether segment is not 1,2-propylene glycol, but phenol, and the catalyst is potassium hydroxide, wherein A 1 is n2 is 12, m2 is 13, R6 is -( CH2 ) 4- , and n is 2.
  • the dispersant is:
  • Example 23 the product prepared in the synthesis process of Example 22 is directly used as a dispersant, and the specific structural formula is as follows:
  • Example 24 and Example 23 are basically the same, except that in the last step of the preparation process of the product, water is not added for hydrolysis, but phenol is added to react at 50°C for 10 hours to generate the product, which is directly used as a dispersant.
  • the specific structural formula is
  • Example 25 and Example 7 are basically the same, except that phenol is not initially input into the synthesis of the polyether segment, and A1 in the product is phenyl.
  • Example 26 The preparation method of Example 26 is basically the same as that of Example 22, except that the positive electrode active material is carbon-coated lithium manganese iron phosphate, and the specific preparation method thereof is:
  • Step S1 689.6 g of manganese carbonate, 455.27 g of ferrous carbonate, 4.65 g of cobalt sulfate, and 4.87 g of vanadium dichloride were added to a mixer and mixed thoroughly for 6 hours. The resulting mixture was then transferred to In the reaction kettle, 5L of deionized water and 1260.6g of oxalic acid dihydrate were added, heated to 80°C, stirred at 500rpm for 6h, and mixed evenly until the reaction was terminated without bubbles, to obtain a Fe, Co, and V co-doped manganese oxalate suspension. The suspension was then filtered, dried at 120°C, and sand-milled to obtain Fe, Co, V, and S co-doped manganese oxalate particles with a particle size of 100nm.
  • Step S2 Take 1793.1g of manganese oxalate prepared in step S1, 368.3g of lithium carbonate, 1146.6g of ammonium dihydrogen phosphate and 4.9g of dilute sulfuric acid, add them to 20L of deionized water, stir them thoroughly, and evenly mix and react at 80°C for 10h to obtain a slurry. The slurry is transferred to a spray drying device for spray drying and granulation to obtain a powder.
  • the powder is sintered in a roller kiln at 700°C for 4h to obtain the core of the positive electrode active material Li 0.997 Mn 0.60 Fe 0.393 V 0.004 Co 0.003 P 0.997 S 0.003 O 4 .
  • Step S3 PEG-3000 is selected as the first carbon source, 58.2g of PEG-1000 is dissolved in 500g of deionized water, and then stirred and fully dissolved to obtain an aqueous solution. 1571.9g of the above core material is added to the solution, and stirred and mixed for 6h until the mixture is uniformly mixed. After spray drying, a first sintering treatment is performed, and the first sintering treatment temperature is 600°C, and the first sintering treatment time is 9h, thereby obtaining a first coated positive electrode active material after the first sintering treatment;
  • Step S4 Glucose is selected as the second carbon source, 37.3 g of glucose is dissolved in 500 g of deionized water, and then stirred and fully dissolved to obtain a glucose aqueous solution. 1603.3 g of the first coated positive electrode active material obtained in step S3 is added to the aforementioned glucose solution, stirred and mixed for 6 hours until the mixture is uniformly mixed, and then spray-dried and subjected to a second sintering treatment, the temperature of the second sintering treatment is 750° C., and the time of the second sintering treatment is 20 hours, thereby obtaining a positive electrode active material after the second sintering treatment.
  • Example 27 and 28 are basically the same as those of Example 26, except that the preparation methods of the positive electrode active materials are different.
  • the specific parameters of the differences are:
  • Example 27 the first carbon source is PEG-10000, the first sintering temperature is 500°C, and the first sintering treatment time is 5 hours.
  • the second carbon source is glucose, the second sintering temperature is 550°C, and the second sintering treatment time is 20 hours.
  • Example 28 the first carbon source is PEG-2000, the first sintering temperature is 660° C., and the first sintering treatment time is 9 h.
  • the second carbon source is sucrose, the second sintering temperature is 750° C., and the second sintering treatment time is 6 h.
  • Comparative Example 1 The preparation method of Comparative Example 1 is substantially the same as that of Example 1, except that no dispersant is added.
  • Comparative Example 2 The preparation method of Comparative Example 2 is substantially the same as that of Example 1, except that the dispersant is
  • Comparative Example 3 and Example 26 are basically the same, except that the dispersant in Comparative Example 3 is the same as that in Comparative Example 2.
  • Comparative Example 4 and Example 27 are basically the same, except that the dispersant in Comparative Example 4 is the same as that in Comparative Example 2.
  • Comparative Example 5 and Example 28 are basically the same, except that the dispersant in Comparative Example 5 is the same as that in Comparative Example 2.
  • a Waters 2695 Isocratic HPLC gel chromatograph (differential refractive index detector 2141) was used.
  • a 3.0% polystyrene solution sample was used as a reference, and a matching chromatographic column (oily: Styragel HT5 DMF7.8*300mm+Styragel HT4) was selected.
  • a 3.0% polymer solution was prepared with purified N-methylpyrrolidone (NMP) solvent. Let the solution stand for a day for later use. When testing, first use a syringe to draw tetrahydrofuran and rinse it, repeat several times. Then draw 5ml of the experimental solution, remove the air in the syringe, and wipe the needle tip dry. Finally, slowly inject the sample solution into the injection port. Obtain data after the display is stable.
  • the thickness of the carbon coating layer was tested by cutting a thin slice of about 100 nm from the middle of a single particle of the positive active material prepared above by FIB, and then the thin slice was tested by TEM to obtain the original TEM test image and save the original image format (xx.dm3).
  • the original image obtained by the above TEM test was opened in the Digital Micrograph software, and the carbon coating layer was identified through the lattice spacing and angle information, and the thickness of the carbon coating layer was measured. The thickness of the selected particle was measured at three positions and the average value was taken.
  • the maximum solid content of the positive electrode slurry refers to the maximum solid content of the slurry that meets the shipping viscosity between 4000 and 35000 mPa.s and does not gel after the slurry is left to stand for 24 hours.
  • the maximum volume energy density refers to the volume energy density of the battery measured when the positive electrode is at the ultimate compaction density.
  • the discharge energy measurement method of a battery cell is as follows:
  • the battery cell was left at rest for 2 hours at 25°C to ensure that the temperature of the battery cell was 25°C. After charging the battery cell at 0.33C to the charging cut-off voltage at 25°C, the constant voltage charging was continued at the charging cut-off voltage until the current reached 0.05C and the charging was cut off (where C represents the rated capacity of the battery cell). After the battery cell was left at rest for 1 hour at 25°C, the battery cell was discharged at 0.33C to the discharge cut-off voltage at 25°C, and the total discharge capacity C0 released by the battery cell was recorded, and the total discharge energy was E0.
  • the battery cell volume measurement method is as follows:
  • the length, width and height of the battery cell are measured to calculate the volume value M0 of the battery cell.
  • Battery energy density battery cell discharge energy E0/battery cell volume M0.
  • the voltage calibration method is as follows:
  • the cycle test process is as follows:
  • Cn/C0 is recorded as the cycle capacity retention rate, which is used as an indicator to evaluate the battery cycle performance.
  • the embodiments all include the polymer dispersant shown in Formula I, which can effectively increase the maximum solid content of the slurry, shorten the filtration time, improve the production efficiency and quality of the electrode, and improve the flexibility of the electrode.
  • At least one of R 1 and R 3 comprising a poly(ethylene oxide-propylene oxide) polyether segment can more effectively exert the dispersing and softening effect than a polyethylene oxide polyether segment, further improving the maximum solid content of the slurry and the flexibility of the electrode.
  • Example 19 From the comparison between Example 19 and Example 7, it can be seen that when both R1 and R3 are polyether segments, the slurry filtration time can be further reduced and the electrode flexibility can be improved compared with only one of the two being a polyether segment.
  • the weight average molecular weight of the polymer is 2000-5000, which can further exert the dispersing effect, increase the maximum solid content of the slurry, and shorten the filtration time.
  • the end group of the polyether segment includes a phenyl group, which can further improve the dispersibility of the slurry.
  • the mass content of the polymer is 0.1%-2.0%, and the slurry has a high maximum solid content, a short filtration time, and high flexibility.
  • the mass content of the polymer is 0.2%-1.0% based on the total mass of the dry material of the positive electrode slurry, the processing performance of the pole piece and the energy density of the battery can be further taken into account.
  • the positive electrode slurry includes a vinylidene fluoride polymer with a weight average molecular weight of not less than 700,000 as a binder, which can further reduce the amount of binder used and improve the flexibility of the electrode.
  • phosphate polymers can more effectively increase the solid content of the slurry, shorten the filtration time, and improve the flexibility of the electrode compared to phosphite polymers; and phosphate polymers have better stability, and can effectively improve the cycle capacity retention rate of the battery on the basis of improving the dispersibility of the slurry.

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Abstract

本申请提供了一种聚合物、其制备方法、正极极片、二次电池、用电装置。聚合物包含式Ⅰ所示的结构，其中X包括磷酸酯基或亚磷酸酯基，R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段；R2包含有机链段。本申请提供的聚合物能够在有效提高正极浆料最大固含量、缩短过滤时间、提高极片生产效率和质量的同时改善极片的柔性。

Description

聚合物、其制备方法、正极极片、二次电池、用电装置
交叉引用
本申请引用于2023年8月1日递交的名称为“聚合物、其制备方法、正极极片、二次电池、用电装置”的第202310961340.X号中国专利申请及2023年8月29日递交的名称为“聚合物、其制备方法、正极极片、二次电池、用电装置”的第202311098921.1号中国专利申请，其通过引用被全部并入本申请。
技术领域
本申请涉及二次电池技术领域，尤其涉及一种聚合物、其制备方法、正极极片、二次电池、用电装置。
背景技术
近年来，二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。
二次电池中的极片往往是通过将含有活性材料的浆料涂覆在集流体上干燥后制备而成的，增加浆料中的溶剂含量、降低浆料的固含量是优化浆料分散均匀性、提高浆料涂覆质量的有效手段，然而高溶剂含量的浆料需要的干燥时间长、制造成本高，如何在提高浆料固含量的同时保证浆料的分散均匀性，进而有效地提高浆料最大固含量是本领域亟需解决的技术问题。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种能够提高浆料最大固含量的分散剂。
本申请的第一方面提供一种聚合物，所述聚合物包含式Ⅰ所示的结构，
其中X包括磷酸酯基或亚磷酸酯基，R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段；R2包含有机链段。
该聚合物能够在有效提高正极浆料最大固含量、缩短过滤时间、提高极片生产效率和质量的同时改善极片的柔性。
在任意实施方式中，R2的有机链段中包含酰胺基团、氨基、芳基中的至少一种。
聚合物中的含氮基团或芳基有助于提高聚合物与正极活性材料的锚固作用，使得聚合物尤其适用于碳包覆正极活性材料，进一步提高聚合物作为分散剂的通用性，通过增加分散剂的锚固位点，更加有效地发挥聚合物的分散作用，从而进一步提高浆料的最大固含量，提升极片成型质量的同时降本增效。
在任意实施方式中，R2的有机链段中还包括C2-12烃基。
聚合物中包含C2-12烃基有助于进一步提高聚合物与碳改性正极活性材料的锚固作用，烃基与正极活性材料上的碳能够有效锚固，增加聚合物在正极活性材料上锚固位点的分散性，从而进一步提高聚合物分散剂的适用范围，提升浆料的最大固含量，优化极片成型质量的同时降本增效。
在任意实施方式中，R2包含式II所示的结构
其中，R4与R5无规共聚，R4包括C2-12亚烃基、C3-13酰胺基中的至少一种、R5包括 中的至少一种；
其中，q1、q2、q3、q4各自独立地包括0-4之间的任意整数，R6 a、R6 b包含氢、C1-4烷基中的至少一种，1≤s≤6，1≤t≤10。
上述结构的有机链段通过含氮基团与烃基的共聚可以更加有效地发挥锚固作用，提升聚合物的分散作用，有效提高浆料的固含量。
在任意实施方式中，R2包含式III所示的结构
其中，R6包括C2-12亚烃基，R7包括中的至少一种；其中,q5、q6各自独立地包括0-4之间的任意整数，1≤n≤6。
上述结构的有机链段通过含氮基团与烃基的交替共聚可以更加有效地发挥锚固作用，提升聚合物的分散作用，有效提高浆料的固含量。
在任意实施方式中，R2的端基包含-C(O)-NH2、-CH2-NH2的至少一种。
端基包含-C(O)-NH2、-CH2-NH2的聚合物能够更加有效地发挥分散作用，提高浆料的最大固含量，进而提高极片的成型质量和效率。
在任意实施方式中，R1、R3中至少一者包含聚醚链段，可选地，R1和R3中均包括聚醚链段。
在任意实施方式中，R1、R3中至少一者包含式IV所示的聚醚链段
其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤50，4≤n1≤50。
具有上述结构的聚醚链段具有合适的空间位阻和低的玻璃化转变温度，能够更加有效地降低正极浆料中粘结剂结晶的有序度和玻璃化转变温度，从而降低粘结剂的结晶度，改善极片的柔性，通过分散和增柔的作用，提高极片的均匀性和柔性，从而提高电池的安全性能和极限压实密度，使得电池的正极活性材料负载量得以提高，助力电池能量密度的进一步提升。
在任意实施方式中，所述聚醚链段的端基包括芳基。
芳基与正极活性材料表面的碳层具有优异的相容性，有助于进一步提高聚合物与碳改性正极活性材料的锚固作用，借助于芳基与正极活性材料上的碳能够有效锚固，增加聚合物在正极活性材料上锚固位点的分散性，从而进一步提高聚合物分散剂的适用范围，提升浆料的最大固含量，优化极片成型质量的同时降本增效。
在任意实施方式中，X包括磷酸酯基。
磷酸酯类聚合物能够更加有效地提升浆料固含量，缩短过滤时间，改善极片柔性；且磷酸酯类聚合物具有更好的稳定性，在提升浆料分散性的基础上还能够有效提高电池的循环容量保持率。
在任意实施方式中，所述聚合物包括下式所示聚合物的至少一种：

其中，R1、R3中至少一者包含式IV所示的嵌段共聚聚醚链段
其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤15，4≤n1≤15，R6、R4各自独立地包括C4-8亚烷基、C4-8亚烯基中的至少一种。
在任意实施方式中，所述聚合物如下式所示：
其中，R2包括氢、芳基、取代或未取代的烷基、含有氨基或酰胺基的有机链段中的至少一种，
R1、R3中至少一者包含式IV所示的嵌段共聚聚醚链段
其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤50，4≤n1≤50，且所述聚醚链段的端基包括苯基。
在任意实施方式中，聚合物的重均分子量为1000-10000，可选为2000-5000。
重均分子量在上述区间范围内的聚合物既能发挥优异的分散性，进一步提高浆料的固含量；又能够使得浆料具有优异的流动性能，减少涂布时间，提高涂布的均匀性和速度。聚合物的重均分子量为2000-5000能够更加有效地起到分散作用，提高浆料的最大固含量、缩短过滤时间。
本申请的第二方面提供一种聚合物的制备方法，制备方法包括：
将式VI所示化合物与R3OH、R1OH、水、含有不饱和键的聚合单体反应制备包含式Ⅰ所示结构的聚合物，
其中，X包括磷酸酯基或亚磷酸酯基，X1、X2、X3均包含卤素；R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段；R2包括有机链段。
在任意实施方式中，所述制备方法包括以下步骤：
将式VI所示化合物与R3OH、R1OH、水进行第一反应制备式VII所示的中间产物，
将所述中间产物与包含含有不饱和键的酰胺、含有不饱和键的胺中的至少一种的聚合单体进行第二反应制备所述聚合物。
在任意实施方式中，所述第二反应具体包括以下步骤：
所述中间产物与含有不饱和键的酰胺、含有不饱和键的胺中的至少一种加成反应后，再与卤素取代的有机醇发生取代反应；
将上述加成反应和取代反应顺序循环多次后制备所述聚合物；
其中，R2包含式III所示的结构
其中，R6包括C2-12烃基，R7包括中的至少一种；其中,q5、q6各自独立地包括0-4之间的任意整数，1≤n≤6。
在任意实施方式中，所述制备方法还包括以下步骤：
所述中间产物与(i)含有不饱和键的酰胺、含有不饱和键的胺中的至少一种、(ii)含有不饱和键的烃类单体、环酰胺单体中的至少一种进行第三反应制备所述聚合物，其中，R2包含式II所示的结构
其中，R4与R5无规共聚，R4包括C2-12烃基、C3-13酰胺基中的至少一种、R5包括中的至少一种；
其中，q1、q2、q3、q4各自独立地包括0-4之间的任意整数，R6 a、R6 b包含氢、C1-4烷基中的至少一种，1≤s≤6，1≤t≤10。
本申请的另一方面提供一种聚合物的制备方法，所述制备方法包括：将式VI所示化合物与包含R3OH、R1OH在内的原料反应制备包含式Ⅰ所示结构的聚合物，
其中，X包括磷酸酯基或亚磷酸酯基，X1、X2、X3均包含卤素；R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段，所述聚醚链段的至少一者的端基包括芳基；R2包括有机链段。
本申请的第三方面提供一种聚合物或任意实施方式的制备方法制备的聚合物作为分散剂的用途。
本申请的第四方面提供一种正极浆料，包括分散剂，所述分散剂包括权利要求第一方面的聚合物或第二方面的制备方法制备的聚合物。
该正极浆料具有高的固含量，有助于改善正极膜层的成型效率和成型质量，提高电池的电化学表现和加工效率。
在任意实施方式中，所述正极浆料中包括正极活性材料，所述正极活性材料包括含锂磷酸盐及其碳改性材料的至少一种；可选地，所述正极活性材料包括磷酸铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料、磷酸铁锂及其掺杂材料的碳包覆材料、磷酸锰铁锂及其掺杂材料的碳包覆材料的至少一种。
聚合物呈负电性，与呈弱酸性的含锂磷酸盐能够通过静电作 用进一步加强相互锚固，从而提高聚合物对含锂磷酸盐的分散作用。而且，含锂磷酸盐导电性差，因此，在正极活性材料制备过程中常采用烧结葡萄糖、蔗糖等有机物包覆碳层的方式提高其导电性。该聚合物同时具有与碳包覆层相互锚固的基团，对碳改性含锂磷酸盐也具有优异的分散作用，能够进一步提高其浆料的分散性，从而提高浆料的最大固含量。
在任意实施方式中，所述正极活性材料包括内核以及碳包覆层，所述碳包覆层至少覆盖所述内核的部分表面，其中，所述碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.2，可选为不小于0.5，可选为不小于0.8。
在内核表面形成碳包覆层能够改善正极活性材料的电导率，当内核表面碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.5时，正极活性材料碳包覆层结构的有序性较高，碳包覆层的孔结构具有较高的致密性和较小的孔径分布范围，在电池的生产过程中，外界的水分很难进入碳包覆层的孔内，从而有效降低了正极活性材料的吸水性和储水性能，实现电池安全性能和循环性能的提高，有效节省烘干过程中的能耗，显著降低生产成本。
但是sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.5的碳包覆层石墨化度高，使得正极活性材料易于团聚，在制浆过程中难以有效分散。本申请实施例提供的分散剂与石墨化度高的碳包覆层具有丰富的锚固基团，尤其适用于包覆层石墨化度高的正极活性材料的分散，通过二者的搭配能够同时提高电池的使用性能和加工性能。
在任意实施方式中，所述碳包覆层的厚度不大于15nm；可选地，所述碳包覆层的厚度不大于10nm，可选地，所述碳包覆层的厚度为4nm-8nm。上述厚度范围内的碳包覆层能够在内核的表面形成较薄碳包覆层即可有效改善正极活性材料的导电性，并且可以改善使用正极活性材料制备电池极片时的压密性能。
在任意实施方式中，基于所述正极浆料的干料总质量计，所 述聚合物的质量含量为0.1％-2.0％，可选为0.2％-1.0％。
上述范围内的聚合物既能起到有效的分散作用，又能同时兼顾电池的体积能量密度，不会对电池的电化学表现产生严重负面影响。
在任意实施方式中，所述正极浆料包括粘结剂，所述粘结剂包括重均分子量不小于30万的偏氟乙烯聚合物，可选地，所述粘结剂的重均分子量为70万-900万。
重均分子量在此区间内的偏氟乙烯聚合物具有优异的粘结性能和电化学稳定性，采用重均分子量为70万-900万的偏氟乙烯聚合物可以进一步降低偏氟乙烯的用量，减少正极膜层的刚性、提高极片的柔性，进而提高电池的极限压实密度，助力电池能量密度的提升。
在任意实施方式中，所述正极浆料的最大固含量不低于60％，可选为60％-80％。
本申请的第五方面提供一种正极极片，所述正极极片包括正极膜层，所述正极膜层是通过任意实施方式的正极浆料制备的或者所述正极膜层中包括分散剂，所述分散剂包括第一方面的聚合物或第二方面的制备方法制备的聚合物。
在任意实施方式中，所述正极极片在压实密度为2.6g/cm3时的可对折次数不小于2次，可选为3-6次。
聚合物不但能够有效提高浆料的固含量，还能同时起到增柔剂的作用，提高正极极片的柔性，进一步改善电池的安全性能和电化学性能。
在任意实施方式中，所述正极极片的面密度不低于300mg/1540.25cm2，可选为300mg/1540.25cm2-600mg/1540.25cm2。
聚合物能够有效提高浆料的最大固含量，使得涂布速度增速30％以上，尤其适用于高速涂布以及厚涂布的成型方式，能够有效解决厚涂布过程中极片易开裂的问题，助于制备柔韧性高、卷绕成型后无裂纹的正极极片。
在任意实施方式中，所述正极膜层包括分散剂，所述分散剂包含式Ⅰ所示的结构，
其中X包括磷酸酯基或亚磷酸酯基，R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段，R2包含有机链段；可选地，R2的有机链段中包含酰胺基团、氨基中的至少一种，可选地，所述聚醚链段的端基包括芳基；所述正极活性材料包括磷酸铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料、磷酸铁锂及其掺杂材料的碳包覆材料、磷酸锰铁锂及其掺杂材料的碳包覆材料的至少一种；可选地，所述正极活性材料包括磷酸锰铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料的碳包覆材料的至少一种；基于所述正极膜层的总质量计，所述分散剂的质量含量为0.1％-2.0％，可选为0.2％-1.0％。
该正极膜层具有良好的分散性和可加工性，有利于制造效率和电池性能的提高。
本申请的第六方面提供一种二次电池，包括第五方面的正极极片。
本申请的第七方面提供一种用电装置，包括第六方面的二次电池。
附图说明
图1是本申请一实施方式的聚合物分散机理的示意图；
图2是本申请一实施方式的二次电池的示意图；
图3是图2所示的本申请一实施方式的二次电池的分解图；
图4是本申请一实施方式的电池模块的示意图；
图5是本申请一实施方式的电池包的示意图；
图6是图5所示的本申请一实施方式的电池包的分解图；
图7是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳
体；52电极组件；53盖板；6聚合物；61锚固基团；62柔性链段；7正极活性材料。
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聚合物、其制备方法、正极极片、二次电池、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)。
为了提高电池的动力学性能和电化学表现，正极活性材料的合成趋向纳米化和更致密的碳包覆，正极活性材料因此具有更大的比表面积，导致合浆过程中需要更多的溶剂进行有效分散，从而降低了浆料的固含量。低固含量的浆料在极片涂布干燥过程中需要延长干燥时间，导致低的生产效率和高能耗；同时低固含量的浆料在长时间的加热干燥过程中，可能出现极片翘边、干裂及粘结剂上浮等恶化极片质量的问题。
基于此，本申请的第一方面提供了一种聚合物，其包含式Ⅰ所示的结构，
其中X包括磷酸酯基或亚磷酸酯基，R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段；R2包含有机链段。
在本文中，聚合物一方面包括通过聚合反应制备的化学上均一的、但在聚合度、摩尔质量和链长方面不同的大分子的集合体；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聚合物。
在一些实施方式中，聚合物包括磷酸酯类聚合物。磷酸酯类聚合物的结构如式V所示：
在一些实施方式中，聚合物包括亚磷酸酯类聚合物。亚磷酸酯类聚合物的结构式如V’所示：
在本文中，聚醚链段是指结构单元中包含醚键(-C-O-C-)的聚合物链段。
在本文中，聚酯链段是指结构单元中包含酯基(-COO-)的聚合物链段。
在本文中，烃基是指包含碳、氢原子的基团，其包括但不限 于烷基、烯基、炔基。
在本文中，有机链段既可以是重复的结构单元聚合而成的，也可以是小分子单体形成的有机基团。本申请实施例提供的聚合物的分散机理如图1所示。聚合物6包括锚固基团61和柔性链段62，聚合物6一端的锚固基团61作用于正极活性材料7表面，通过柔性链段62的空间位阻效应达到分散的目的。该聚合物6中的磷酸酯基团或亚磷酸酯基团能够通过分子间作用力或静电作用有效锚固于正极活性材料7的表面，起到锚固基团61的作用。借助于锚固基团在正极活性材料表面的锚固作用，聚醚链段、聚酯链段等柔性链段62的空间位阻效应得以在正极活性材料颗粒表面有效发挥，起到阻隔正极活性材料7团聚的作用，进而提高单位体积溶剂内能有效分散的正极活性材料7数量，减缓匀浆过程中浆料的凝胶和团聚现象，降低浆料粘度，显著提升浆料的有效固含量，降低浆料的过滤时间，提高极片的成型效率和质量。本申请实施例提供的聚合物能够使得浆料适用于厚涂布工艺，有助于电池能量密度的提升。
同时，聚合物中的聚醚链段、聚酯链段这些柔性链段具有合适的空间位阻和低的玻璃化转变温度，能够通过柔性链段的运动改善极片的柔性，同步起到分散和增柔的作用。
在一些实施方式中，R2的有机链段中包含酰胺基团、氨基、芳基中的至少一种。
在本文中，酰胺基团是指基团，其既包括伯酰胺，也包括仲酰胺和叔酰胺。
在本文中，氨基基团是指基团，其既包括伯氨基，也包括仲氨基和叔氨基。
在本文中，“芳基”是指衍生自从单环或多环芳族烃中去除氢原子的有机基团。作为示例，芳基包括但不限于苯基、萘基、苄基。芳基可以是未取代的或被一个或多个合适的取代基取代的。
此外，芳基可以是单环或多环的。在一些实施方式中，芳基至少包含6、7、8、9或10个碳原子。采用红外吸收光谱对包含酰胺基团的聚合物进行表征，能够观测到羰基位于1900cm-1～1650cm-1波段的吸收峰，以及酰胺基团位于3500cm-1～3100cm-1波段的中等强度的双峰吸收峰。
聚合物中的含氮基团或芳基基团有助于提高聚合物与正极活性材料的锚固作用，使得聚合物尤其适用于碳包覆正极活性材料，进一步提高聚合物作为分散剂的通用性，通过增加分散剂的锚固位点，更加有效地发挥聚合物的分散作用，从而进一步提高浆料的最大固含量，提升极片成型质量的同时降本增效。
在一些实施方式中，R2的有机链段中还包含C2-12烃基。
在本文中，“C2-12烃基”是指仅由碳和氢原子组成的直链或支链烃链基团，基团中既可以不存在不饱和，也可以存在不饱和，具有从二至十二个个碳原子，并且通过至少一个单键附接到分子的其余部分。C2-12烃基的示例包括但不限于：C2-12烷基、C2-12亚烷基、C2-12烯基、C2-12亚烯基。例如，亚乙基、乙基、正丙基、1-甲基乙基(异丙基)、亚异丙基、1,3-亚丙基、丁基、异丁基、叔丁基、1、4-亚丁基、1,3-亚丁基、2-亚丁烯基、戊基、异戊基、新戊基、己基、庚基、辛基等。聚合物中包含C2-12烃基有助于进一步提高聚合物与碳改性正极活性材料的锚固作用，烃基与正极活性材料上的碳能够有效锚固，增加聚合物在正极活性材料上锚固位点的分散性，从而进一步提高聚合物分散剂的适用范围，提升浆料的最大固含量，优化极片成型质量的同时降本增效。
在一些实施方式中，R2包含如式II所示的结构：
其中，R4与R5无规共聚，R4包括C2-12亚烃基、C3-13酰胺基中的至少一种，R5包括 中的至少一种；
其中，q1、q2、q3、q4各自独立地包括0-4之间的任意整数，R6 a、R6 b包含氢、C1-4烷基中的至少一种，1≤s≤6，1≤t≤10。
C2-12亚烃基是指具有2-12个碳原子的二价烃基；包括C2-12亚烷基、C2-12亚烯基。作为示例，C2-12亚烷基包括但不限于1,2-亚乙基、1,2-亚丙基、1,3-亚丙基、1,3-亚丁基、1,4-亚丁基、2-甲基-1,3-亚丙基、1,1-二甲基-1,2-亚乙基、1,4-亚戊基、1,5-亚戊基、2-甲基-1,4-亚丁基、2,2-二甲基-1,3-亚丙基、1,6-亚己基、2-甲基-1,5-亚戊基、3-甲基-1,5-亚戊基、2,3-二甲基-1,4-亚丁基、1,7-亚庚基、2-甲基-1,6-亚己基、3-甲基-1,6-亚己基、2-乙基-1,5-亚戊基、3-乙基-1,5-亚戊基、2,3-二甲基-1,5-亚戊基、2,4-二甲基-1,5-亚戊基、1,8-亚辛基、2-甲基-1,7-亚庚基、3-甲基-1,7-亚庚基、4-甲基-1,7-亚庚基、2-乙基-1，6-亚己基、3-乙基-1,6-亚己基、2,3-二甲基-1,6-亚己基、2,4-二甲基-1,6-亚己基、1,9-亚壬基、2-甲基-1,8-亚辛基、3-甲基-1,8-亚辛基、4-甲基-1,8-亚辛基、2-乙基-1,7-亚庚基、3-乙基-1,7-亚庚基、1,10-亚癸基、2-甲基-1,9-亚壬基、3-甲基-1,9-亚壬基、4-甲基-1,9-亚壬基、5-甲基-1,9-亚壬基、1,11-亚十一烷基、2-甲基-1,10-亚癸基、3-甲基-1,10-亚癸基、5-甲基-1,10-亚癸基、1,12-亚十二烷基。
C2-12亚烯基为至少含有一个双键的二价烃基。作为示例，C2- 12亚烯基包括例如亚乙烯基、亚丙烯基、1-甲基亚乙烯基、1-亚丁烯基、2-亚丁烯基、1-甲基亚丙烯基、2-甲基亚丙烯基、1-亚戊烯基、2-亚戊烯基、1-甲基-1-亚丁烯基、1-甲基-2-亚丁烯基、1-亚己烯基、2-亚己烯基、3-亚己烯基、1-甲基-1-亚戊烯基、1-甲基-2-亚戊烯基、1-甲基-3-亚戊烯基、1,4-二甲基-1-亚丁烯基、1,4-二甲基-2-亚丁烯基、1-亚庚烯基、2-亚庚烯基、3-亚庚烯基、1-亚辛烯基、2-亚辛烯 基、3-亚辛烯基。
在一些实施方式中，C3-13酰胺基包含如下基团：
其中x为2～12，可选为2～5。
在一些实施方式中，x为2、3、4、5、6、7、8、9、10、11或12。
在本文中，C1-4烷基包括甲基、乙基、丙基、异丙基、2-甲基-1-丙基、2-甲基-2-丙基中的至少一种。
在一些实施方式中，s为1、2、3、4、5、6中的任意一种。
在一些实施方式中，t为1、2、3、4、5、6、7、8、9、10中的任意一种。
在一些实施方式中，q1、q2、q3、q4各自独立地选自0、1、2、3或4。
上述结构的有机链段包括含氮基团与亚烃基，可以更加有效地发挥锚固作用，提升聚合物的分散作用，有效提高浆料的固含量。
在一些实施方式中，R2包含式III所示的结构
其中，R6包括C2-12亚烃基，R7包括中的至少一种；其中,q5、q6各自独立地包括0-4之间的任意整数，1≤n≤6。
在一些实施方式中，q5、q6各自独立地包括0、1、2、3或4。
在一些实施方式中，n为1、2、3、4、5、6中的任意一种。
上述结构的有机链段通过含氮基团与亚烃基的交替排列可以更加有效地发挥锚固作用，提升聚合物的分散作用，有效提高浆料的固含量。
在一些实施方式中，R2的端基包含-C(O)-NH2、-CH2-NH2的至少一种。
端基包含-C(O)-NH2、-CH2-NH2的聚合物能够更加有效地发挥分散作用，提高浆料的最大固含量，进而提高极片的成型质量和效率。
在一些实施方式中，R1、R3中至少一者包含聚醚链段。在一些实施方式中，R1和R3中均包括聚醚链段。采用红外吸收光谱对包含聚醚链段的聚合物进行表征，能够观测到醚键吸收峰位于1250～1100cm-1波段。
在一些实施方式中，R2包括H、芳基中的至少一种。
在一些实施方式中，R1、R3中一者包含聚醚链段，另一者包含C1-4烷基。
在一些实施方式中，R1和R3中均包括聚醚链段。
R1和R3中均包括聚醚链段相比于R1、R3中一者包含聚醚链段，另一者包含C1-4烷基，聚合物使得浆料的过滤性进一步优化，极片柔性进一步提高。
在一些实施方式中，R1、R3中至少一者包含式IV所示的聚醚链段
其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤50，4≤n1≤50。
在一些实施方式中，聚醚链段为嵌段共聚链段。在一些实施方式中，聚醚链段为无规共聚链段。
在一些实施方式中，m1、n1可独立地选自4、5、6、7、8、9、10、11、12、13、14、15、20、25、30、35、40、45、50或任意二者间的任意数值。
具有上述结构的聚醚链段具有合适的空间位阻和低的玻璃化转变温度，能够更加有效地降低正极浆料中粘结剂结晶的有序度和 玻璃化转变温度，从而降低粘结剂的结晶度，改善极片的柔性，通过分散和增柔的作用，提高极片的均匀性和柔性，从而提高电池的安全性能和极限压实密度，使得电池的正极活性材料负载量得以提高，助力电池能量密度的进一步提升。
在一些实施方式中，聚醚链段的端基包括芳基。
芳基与正极活性材料表面的碳层具有优异的相容性，有助于进一步提高聚合物与碳改性正极活性材料的锚固作用，借助于芳基与正极活性材料上的碳能够有效锚固，增加聚合物在正极活性材料上锚固位点的分散性，从而进一步提高聚合物分散剂的适用范围，提升浆料的最大固含量，优化极片成型质量的同时降本增效。
在一些实施方式中，X包括磷酸酯基。
磷酸酯类聚合物能够更加有效地提升浆料固含量，缩短过滤时间，改善极片柔性；且磷酸酯类聚合物具有更好的稳定性，在提升浆料分散性的基础上还能够有效提高电池的循环容量保持率。
在一些实施方式中，聚合物包括下式所示聚合物的至少一种：

其中，R1、R3中至少一者包含式IV所示的嵌段共聚聚醚链段
其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤15，4≤n1≤15。
在一些实施方式中，R6、R4各自独立地包括C4-8亚烷基、C4-8亚烯基中的至少一种。
在一些实施方式中，R6、R4各自独立地包括-(CH2)4-、-(CH2)5-、-(CH2)6-、-(CH2)7-、-(CH2)8-、基团中的至少一种。
在一些实施方式中，聚醚链段的端基包括苯基。
在一些实施方式中，所述聚合物如下式所示：
其中，R2包括氢、芳基、取代或未取代的烷基、含有氨基或酰胺基的有机链段中的至少一种，R1、R3中至少一者包含式IV所示的嵌段共聚聚醚链段，
其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤50，4≤n1≤50，且所述聚醚链段的端基包括苯基。
在一些实施方式中，聚合物的重均分子量为1000-10000。在 一些实施方式中聚合物的重均分子量为2000-5000。
重均分子量具有本领域公知的含义，可以通过本领域公知的方法进行测试。作为示例，重均分子量可以通过凝胶色谱法进行测试。
在一些实施方式中，聚合物的重均分子量为1000、2000、3000、4000、5000、6000、7000、8000、9000、10000或其间的任意数值。
重均分子量在上述区间范围内的聚合物既能发挥优异的分散性，进一步提高浆料的固含量；又能够使得浆料具有优异的流动性能，减少涂布时间，提高涂布的均匀性和速度。聚合物的重均分子量为2000-5000能够更加有效地起到分散作用，提高浆料的最大固含量、缩短过滤时间。
本申请的第二方面提供一种聚合物的制备方法，所述制备方法包括下列步骤：
将式VI所示化合物与R3OH、R1OH、水、含有不饱和键的聚合单体反应制备包含式Ⅰ所示结构的聚合物，
其中，X包括磷酸酯基或亚磷酸酯基，X1、X2、X3均包含卤素；R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段；R2包括有机链段。
在本文中，卤素包括氟、氯、溴、碘中的至少一种。
在一些实施方式中，式VI中磷与氧通过双键相连，式I中X 为磷酸酯基。
在一些实施方式中，式VI中不包括氧，式I中X为亚磷酸酯基。
在一些实施方式中，式VI包括POCl3或PCl3。
在一些实施方式中，所述制备方法包括以下步骤：
将式VI所示化合物与R3OH、R1OH、水进行第一反应制备式VII所示的中间产物，
将所述中间产物与包含含有不饱和键的酰胺、含有不饱和键的胺中的至少一种的聚合单体进行第二反应制备所述聚合物。
在一些实施方式中，第一反应具体包括：
在搅拌状态下向式VI所示化合物中滴加R3OH，保持反应温度低于20℃，搅拌一段时间后升温至40-50℃反应6-7小时后加水，在50-60℃反应3-4小时后获得式A所示的第一中间产物，反应过程中投入的R3OH与式VI所示化合物的摩尔比为1.2-1.5，其中R3包括C1-4烷基，
上述反应条件有利于提高产物纯度。
在一些实施方式中，第一反应还包括：
将聚醚与第一中间产物在100℃-120℃条件下反应4h-7h后生成式VII所示的中间产物，其中，R1包含聚醚链段。
在一些实施方式中，所述第二反应具体包括以下步骤：
所述中间产物与含有不饱和键的酰胺、含有不饱和键的胺中的至少一种加成反应后，再与卤素取代的有机醇发生取代反应；
将上述加成反应和取代反应循环多次后制备所述聚合物；
其中，R2包含式III所示的结构
其中，R6包括C2-12烃基，R7包括中的至少一种；其中,q5、q6各自独立地包括0-4之间的任意整数，1≤n≤6。
加成反应是指双键中π键断开，形成两个单键的反应。
取代反应是指一种原子或基团代替有机物分子中某种原子或基团，并占据其位置的一类化学反应。
在一些实施方式中，所述制备方法还包括以下步骤：
所述中间产物与(i)含有不饱和键的酰胺、含有不饱和键的胺中的至少一种、(ii)含有不饱和键的烃类单体、环酰胺单体中的至少一种进行第三反应制备所述聚合物，其中，R2包含式II所示的结构
其中，R4与R5无规共聚，R4包括C2-12烃基、C3-13酰胺基中的至少一种、R5包括中的至少一种；
其中，q1、q2、q3、q4各自独立地包括0-4之间的任意整数，R6 a、R6 b包含氢、C1-4烷基中的至少一种，1≤s≤6，1≤t≤10。
在一些实施方式中，含有不饱和键的烃类单体包含烯烃单体、炔烃单体、环状烷烃中的至少一种。
在一些实施方式中，环酰胺单体是指包括酰胺键的环状单体。
在一些实施方式中，第三反应具体包括混合中间产物与含有 不饱和键的烃类单体、环酰胺单体中的至少一种反应一段时间后加入含有不饱和键的酰胺、含有不饱和键的胺中的至少一种，发生共聚反应。
在一些实施方式中，制备方法还包括以下步骤：
将端基为羟基的聚合物与包含酰胺基团或氨基的不饱和单体进行封端反应，以制备端基包含酰胺基团或氨基的聚合物。
本申请提供一种聚合物的制备方法，所述制备方法包括：
将式VI所示化合物与包含R3OH、R1OH在内的原料反应制备包含式Ⅰ所示结构的聚合物，
其中，X包括磷酸酯基或亚磷酸酯基，X1、X2、X3均包含卤素；R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段，所述聚醚链段的至少一者的端基包括芳基；R2包括有机链段。
在一些实施方式中，将式VI所示单体与R1OH、R3OH在惰性、碱性环境下反应后加入水或苯酚反应获得聚合物。
在一些实施方式中，将R2包含羟基的聚合物继续与包含含有不饱和键的酰胺、含有不饱和键的胺中的至少一种的聚合单体进行第二反应制备R2中含氮的聚合物。
在一些实施方式中，本申请任意实施方式的聚合物和本申请任意实施方式的制备方法制备的聚合物作为分散剂。
在一些实施方式中，本申请任意实施方式的聚合物和本申请任意实施方式的制备方法制备的聚合物作为二次电池极片浆料中的 分散剂。
在一些实施方式中，本申请任意实施方式的聚合物和本申请任意实施方式的制备方法制备的聚合物作为二次电池正极浆料中的分散剂。
[正极浆料]
本申请的第三方面提供一种正极浆料，正极浆料中包括分散剂，分散剂包括任意实施方式中的聚合物或任意实施方式的制备方法制备的聚合物。
该正极浆料具有高的固含量，有助于改善正极膜层的成型效率和成型质量，提高电池的电化学表现和加工效率。
在一些实施方式中，正极浆料中包括正极活性材料，所述正极活性材料包括含锂磷酸盐及其碳改性材料的至少一种。
在一些实施方式中，含锂磷酸盐包括磷酸铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料中的至少一种。在一些实施方式中，掺杂材料包括任意位点的掺杂材料，可选为锂位掺杂、磷位掺杂、锰位掺杂、铁位掺杂。
在一些实施方式中，碳改性材料包括碳包覆材料、碳掺杂材料中的至少一种。
在一些实施方式中，所述正极活性材料包括磷酸铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料、磷酸铁锂及其掺杂材料的碳包覆材料、磷酸锰铁锂及其掺杂材料的碳包覆材料的至少一种。
聚合物呈负电性，与呈弱酸性的含锂磷酸盐能够通过静电作用进一步加强相互锚固，从而提高聚合物对含锂磷酸盐的分散作用。而且，含锂磷酸盐导电性差，因此，在正极活性材料制备过程中常采用烧结葡萄糖、蔗糖等有机物包覆碳层的方式提高其导电性。该聚合物同时具有与碳包覆层相互锚固的基团，对碳改性含锂磷酸盐也具有优异的分散作用，能够进一步提高其浆料的分散性，从而提高浆料的最大固含量。
在一些实施方式中，所述正极活性材料包括内核以及碳包覆 层，所述碳包覆层至少覆盖所述内核的部分表面，其中，所述碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.2。在一些实施方式中，所述碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于不小于0.5。在一些实施方式中，所述碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于不小于0.8。
在一些实施方式中，碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比可选为0.2、0.3、0.4、0.5、0.6、0,7、0.8、0.9或任意二者间的数值范围。
碳包覆层的碳结构和特征可通过本领域公知方式进行测定。作为示例，可以通过拉曼(Raman)光谱进行测定，具体地：首先测量正极活材料的拉曼图谱，通过对拉曼测试的能谱进行分峰，得到Ig/Id(其中Id为sp3杂化碳原子的峰强度，Ig为sp2杂化碳原子的峰强度，该峰强度比即sp2杂化碳原子的峰高度与sp3杂化碳原子的峰高度之比)，从而得到sp2杂化碳与sp3杂化碳的摩尔比。正极活性材料碳包覆层中的sp2杂化碳原子与sp3杂化碳原子的摩尔比不受特别限制，例如，碳包覆层中的sp2杂化碳原子与sp3杂化碳原子的摩尔比可以不小于0.5，在一些实施例中，碳包覆层中的sp2杂化碳原子与sp3杂化碳原子的摩尔比可以不小于0.8。当碳包覆层中的sp2杂化碳原子与sp3杂化碳原子的摩尔比位于上述范围内时，内核表面的碳包覆层具有较高的石墨化度，碳包覆层的结构更为致密，既能降低碳包覆层的吸水性，又能使得碳包覆层实现良好的导电性，保证锂离子的通路，有利于提高正极活性材料的循环性能和安全性能。
在一些实施方式中，内核包括磷酸盐；在一些实施例中，磷酸盐包括锂锰磷酸盐、锂铁磷酸盐、锂锰铁磷酸盐及其掺杂材料中的至少一种。
在内核表面形成碳包覆层能够改善正极活性材料的电导率，当内核表面碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.5时，正极活性材料碳包覆层结构的有序性较高，碳包覆层的孔结构具有较高的致密性和较小的孔径分布范围，在电池的生产过 程中，外界的水分很难进入碳包覆层的孔内，从而有效降低了正极活性材料的吸水性和储水性能，实现电池安全性能和循环性能的提高，有效节省烘干过程中的能耗，显著降低生产成本。
但是sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.5的碳包覆层石墨化度高，使得正极活性材料易于团聚，在制浆过程中难以有效分散。本申请实施例提供的分散剂与石墨化度高的碳包覆层具有丰富的锚固基团，尤其适用于包覆层石墨化度高的正极活性材料的分散，通过二者的搭配能够同时提高电池的使用性能和加工性能。
在一些实施方式中，内核包括Li1+xMn1-yAyP1-zRzO4，x为在-0.100至0.100范围内的任意数值，y为在0.001至0.500范围内的任意数值，z为在0.001至0.100范围内的任意数值，A包括Zn、Al、Na、K、Mg、Mo、W、Ti、V、Zr、Fe、Ni、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素，R包括B(硼)、S、Si和N中的一种或多种元素。选自上述元素的锰位掺杂元素A有助于减小该材料在脱嵌锂过程中磷酸锰锂的晶格变化率，提高正极活性材料的结构稳定性，大大减少锰的溶出并降低颗粒表面的氧活性；选自上述元素的磷位掺杂元素R还有助于改变Mn-O键长变化的难易程度，从而改善电子电导并降低锂离子迁移势垒，促进锂离子迁移，提高二次电池的倍率性能。
除非另有说明，否则上述内核的化学式中，当某掺杂位点具有两种以上元素时，上述对于x、y、z或m数值范围的限定不仅是对每种作为该位点的元素的化学计量数的限定，也是对各个作为该位点的元素的化学计量数之和的限定。例如，当具有化学式为Li1+xMn1-yAyP1-zRzO4的化合物时，当A为两种以上元素A1、A2……An时，A1、A2……An各自的化学计量数y1、y2……yn各自均需落入本申请对y限定的数值范围内，且y1、y2……yn之和也需落入该数值范围内。类似地，对于R为两种以上元素的情况，本申请中对R化学计量数的数值范围的限定也具有上述含义。
根据本申请的一些实施例，内核的种类不受特别限制，例如，内核可以包括Li1+xCmMn1-yAyP1-zRzO4-nDn，x的大小受A和R的价态大小以及y和z的大小的影响，以保证整个体系呈现电中性。如果x的值过小，会导致整个内核体系的含锂量降低，影响材料的克容量发挥。更具体地，x为在-0.100至0.100范围内的任意数值，y为在0.001至0.500范围内的任意数值，z为在0.001至0.100范围内的任意数值，n为在0.001至0.1范围内的任意数值，m为在0.9至1.1范围内的任意数值。例如，1+x选自0.9至1.1的范围，例如为0.97、0.977、0.984、0.988、0.99、0.991、0.992、0.993、0.994、0.995、0.996、0.997、0.998、1.01，x选自0.001至0.1的范围，例如为0.001、0.005，y选自0.001至0.5的范围，例如为0.001、0.005、0.02、0.05、0.1、0.15、0.2、0.25、0.3、0.34、0.345、0.349、0.35、0.4，z选自0.001至0.1的范围，例如为0.001、0.005、0.08、0.1，n选自0.001至0.1的范围，例如为0.001、0.005、0.08、0.1，并且正极活性材料为电中性的。C包括Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素，A包括Zn、Al、Na、K、Mg、Mo、W、Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素，R包括B(硼)、S、Si和N中的一种或多种元素，D包括S、F、Cl和Br中的一种或多种元素。通过在化合物的Li位、Mn位、P位和O位同时以特定量掺杂特定的元素，能够获得明显改善的倍率性能，同时显著减少了Mn与Mn位掺杂元素的溶出，获得了显著改善的循环性能和/或高温稳定性，并且正极活性材料的克容量和压实密度也可以得到提高。
在一些实施方式中，所述碳包覆层的厚度不大于15nm。在一些实施方式中，所述碳包覆层的厚度不大于10nm。在一些实施方式中，所述碳包覆层的厚度为4nm-8nm。
在一些实施方式中，碳包覆层的厚度可选为4nm、5nm、6nm、7nm、8nm、9nm、10nm、11nm、12nm、13nm、14nm、15nm或任意二者间的数值范围。
碳包覆层的厚度可以参照如下方法测试得到：通过FIB从正极活性材料单个颗粒中间切取100nm左右厚度的薄片，然后对薄片进行透射电镜(TEM)测试，得到TEM测试原始图片，保存原始图片格式(xx.dm3)。将上述TEM测试所得原始图片在Digital Micrograph软件中打开，通过晶格间距和夹角信息，识别出碳包覆层，量取碳包覆层的厚度。对所选颗粒测量三个位置处的厚度，取平均值。
上述厚度范围内的碳包覆层能够在内核的表面形成较薄碳包覆层即可有效改善正极活性材料的导电性，并且可以改善使用正极活性材料制备电池极片时的压密性能。
在一些实施方式中，正极活性材料是通过如下方法制备的：
提供内核；在所述内核的至少部分表面形成碳包覆层，其中，所述碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.2，可选未不小于0.5。
在一些实施方式中，在所述内核的至少部分表面形成碳包覆层包括：通过碳源在所述内核表面形成预碳包覆层以获得预包覆正极活性材料；对所述预包覆正极活性材料进行烧结处理以形成所述碳包覆层，以获得所述正极活性材料，所述碳源包括第一碳源和第二碳源。
在一些实施方式中，在内核表面形成预碳包覆层以获得预包覆正极活性材料，在内核表面形成预碳包覆层的方法不受特别限制，例如，可将碳源与内核置于同一反应容器中，通过水热处理令碳源在内核表面发生反应，从而在内核表面形成碳包覆层；还可以将碳源与内核置于球磨设备，如砂磨机中，通过机械混合使得碳源在内核表面形成碳包覆层。在一些实施方式中，碳源包括第一碳源和第二碳源，第一碳源包括聚乙烯醇、聚乙二醇和柠檬酸中的至少一种；第二碳源包括淀粉、蔗糖和葡萄糖中的至少一种。在一些实施例中，第一碳源的分子量不少于1000，在另一些实施方式中，第一碳源的分子量可以为2000-5000。由此，通过球磨处理即可以在内核表面形 成均匀分布的、厚度较为一致的预碳包覆层，进而有利于烧结处理后形成致密、均匀的碳包覆层孔结构。在一些实施方式中，第二碳源可以包括淀粉、蔗糖和葡萄糖中的至少一种。在一些实施例中，第二碳源可以为葡萄糖。
在一些实施方式中，在惰性气体气氛下对预包覆正极活性材料进行烧结处理。在一些实施方式中，对预包覆正极活性材料进行烧结处理以获得正极活性材料，烧结处理应在惰性气氛下进行，从而避免碳源发生氧化反应从而无法获得具有较高石墨化度的碳包覆层，惰性气体的种类不受特别限制，例如，惰性气体可以包括氮气和氦气中的至少一种。烧结处理的条件不受特别限制，例如，所述烧结处理的温度可以为650℃-800℃，烧结处理的时间可以为6h-12h。由此，可以在内核表面形成具有较高石墨化度的碳包覆层。随着烧结处理的温度升高，碳包覆层中碳的石墨化程度也会升高。通过控制烧结处理的最高烧结处理可以有效控制碳包覆层的石墨化度，碳包覆层具有致密的孔结构和较优的导电性。
在一些实施方式中，所述在所述内核的至少部分表面形成碳包覆层包括：将所述内核与第一碳源混合，并通过第一烧结处理得到第一包覆正极活性材料，将所述第一包覆正极活性材料与第二碳源混合，并通过第二烧结处理得到所述正极活性材料。
在一些实施方式中，第一烧结处理的温度为350℃-800℃，所述第一烧结处理的时间为6h-12h。在一些实施方式中，所述第二烧结处理的温度为650℃-850℃，所述第二烧结处理的时间为6h-24h。
在一些实施方式中，基于所述正极浆料的干料总质量计，所述聚合物的质量含量为0.1％-2.0％。在一些实施方式中，基于所述正极浆料的干料总质量计，所述聚合物的质量含量为0.2％-1.0％。
在一些实施方式中，基于所述正极浆料的干料总质量计，所述聚合物的质量含量可选为0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1.0％、1.1％、1.2％、1.3％、1.4％、1.5％、1.6％、1.7％、1.8％、1.9％、2.0％或其间的任意数值。上述范围内的 聚合物既能起到有效的分散作用，又能同时兼顾电池的体积能量密度，不会对电池的电化学表现产生严重负面影响。
在一些实施方式中，正极浆料包括粘结剂，粘结剂包括重均分子量不小于30万的偏氟乙烯聚合物。在一些实施方式中，所述粘结剂的重均分子量为70万-900万。
在一些实施方式中，偏氟乙烯聚合物为偏氟乙烯均聚物。
在一些实施方式中，偏氟乙烯聚合物为偏氟乙烯共聚物。
重均分子量具有本领域公知含义，可以通过任意公知方法进行测试。在一些实施方式中，通过凝胶色谱法表征粘结剂的重均分子量。
在一些实施方式中，粘结剂的重均分子量可选为70万、100万、200万、300万、400万、500万、600万、700万、800万、900万或其间的任意数值。
重均分子量在此区间内的偏氟乙烯聚合物具有优异的粘结性能和电化学稳定性，采用重均分子量为70万-900万的偏氟乙烯聚合物可以进一步降低偏氟乙烯的用量，减少正极膜层的刚性、提高极片的柔性，进而提高电池的极限压实密度，助力电池能量密度的提升。
在一些实施方式中，正极浆料的最大固含量不低于60％。在一些实施方式中，正极浆料的最大固含量为60％-80％。
正极浆料的最大固含量是指满足在出货粘度介于4000～35000mpa.s时,且正极浆料静置24h后不发生凝胶现象的浆料最大固含量。正极浆料实际固含量测试方法：取浆料重量记为m0，放置于失重率测试仪器；浆料蒸发溶剂至失重率低于0.3％，记剩余重量为m1；固含量＝m1/m0*100％。
在一些实施方式中，正极浆料的最大固含量可选为60％、65％、70％、75％、80％或其间的任意数值。
通过在正极浆料中加入聚合物，有效地提高了浆料的固含量和柔性，改善了极片的柔性和成型效率。
[正极极片]
本申请还提供了一种正极极片，所述正极极片包括正极膜层，所述正极膜层是通过任意实施方式的正极浆料制备的或者所述正极膜层中包括分散剂，所述分散剂包括任意实施方式的聚合物或任意实施方式的制备方法制备的聚合物。
在一些实施方式中，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，正极极片在压实密度为2.6g/cm3时的可对折次数不小于2次。在一些实施方式中，正极极片在压实密度为2.6g/cm3时的可对折次数为3-6次。
正极极片在压实密度为2.6g/cm3时的可对折次数可以用于表征极片的柔性，能够通过任意公知方法测得。作为示例，取无缺陷的、压实密度为2.6g/cm3的正极极片，沿纵向裁剪成长*宽为25cm*4cm宽的样品，样本数≥4片，先将其按纵向方向(25cm方向)进行预对折后，将膜片放置于测试平台，用2kg的圆筒压辊进行辊压1次。若透光，则脆性透光次数为1次。若不透光则重复反向对折辊压。将折痕对光观察，观察是否透光或断裂，记录实际对折次数，测试4次，取平均数作为测试结果。
在一些实施方式中，正极极片在压实密度为2.6g/cm3时的可对折次数可选为2次、3次、4次、5次或6次。
聚合物不但能够有效提高浆料的固含量，还能同时起到增柔剂的作用，提高正极极片的柔性，进一步改善电池的安全性能和电 化学性能。
在一些实施方式中，正极极片的面密度不低于300mg/1540.25cm2。在一些实施方式中，正极极片的面密度为300mg/1540.25cm2-600mg/1540.25cm2。
在一些实施方式中，正极极片的面密度为300mg/1540.25cm2、400mg/1540.25cm2、450mg/1540.25cm2、500mg/1540.25cm2、600mg/1540.25cm2或其间的任意数值。极片的面密度具有公知的含义，并且能够通过任意公知方法测得。
在一些实施方式中，正极极片包含磷酸铁锂，正极极片的面密度不低于360mg/1540.25cm2。在一些实施方式中，正极极片的面密度为360mg/1540.25cm2-600mg/1540.25cm2。
在一些实施方式中，正极极片包含磷酸铁锰锂，正极极片的面密度不低于300mg/1540.25cm2。在一些实施方式中，正极极片的面密度为300mg/1540.25cm2-600mg/1540.25cm2。
聚合物能够有效提高浆料的最大固含量，使得涂布速度增速30％以上，尤其适用于高速涂布以及厚涂布的成型方式，能够有效解决厚涂布过程中极片易开裂的问题，助于制备柔韧性高、卷绕成型后无裂纹的正极极片。
在一些实施方式中，所述正极膜层包括分散剂，所述分散剂包含式Ⅰ所示的结构，
其中X包括磷酸酯基或亚磷酸酯基，R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段，R2包含有机链段；可选地，R2的有机链段中包含酰胺基团、氨基中的至少一种；可选地，聚醚链段的端基包括芳基；所述正极活性材料包括磷酸铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料、磷酸铁锂及其掺杂材料的碳包覆材料、磷酸锰 铁锂及其掺杂材料的碳包覆材料的至少一种；可选地，所述正极活性材料包括磷酸锰铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料的碳包覆材料的至少一种，基于所述正极膜层的总质量计，所述分散剂的质量含量为0.1％-2.0％，可选为0.2％-1.0％。
该正极膜层具有良好的分散性和可加工性，有利于制造效率和电池性能的同步提高。在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂、分散剂分散于溶剂(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。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
[二次电池]
本申请的另一方面提供一种二次电池，二次电池包括任意实施方式的正极极片。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图2是作为一个示例的方形结构的二次电池5。所述二次电池也可以为钠离子电池、镁离子电池、钾离子电池。
在一些实施方式中，参照图3，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
[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4是作为一个示例的电池模块4。参照图4，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
[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5和图6是作为一个示例的电池包1。参照图5和图6，在 电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
[用电装置]
本申请的一个实施方式中，提供一种用电装置，包括任意实施方式的二次电池、任意实施方式的电池模块或任意实施方式的电池包中的至少一种。
所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图7是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1
1)制备分散剂：
第一中间产物的制备
在装有温度计、搅拌器和氯化氢气体收集装置的四口烧瓶中加入POCl3，在搅拌状态下滴加R3OH，保持反应温度低于20℃，搅拌20min后升温至40-50℃，其中n(POCl3)：n(R3-OH)为1.2-1.5，反应6-7h后，向体系中滴加一定量的蒸馏水，在55℃反应3.5h，制备第一中间产物。通过反应参数控制可实现第一中间产物的产率≥95％，其中R3为-CH2CH3。
第二中间产物的制备：
称取1,2丙二醇(环氧乙烷、环氧丙烷单体、第一中间产物总质量的0.4％)、浓硫酸(总质量的0.3％)固体投进反应釜中关闭反应釜盖并用扳手拧紧固定螺栓。对反应釜进行抽真空处理并用高纯氮气置换3次，依次加入环氧乙烷、环氧丙烷，投入的摩尔比为n2：m2，进行嵌段聚合反应，反应过程压力维持在0.3±0.05MPa，温度维持在115±5℃，反应5h后加入第一中间产物，在115±5℃条件下反应5h时间后生成第二中间产物，反应过程示意图如下所示，其中A1为n2为25，m2为25，R3为-CH2CH3。
制备聚合物：
将第二中间产物在室温与丙烯酰胺加成反应12小时，再加入HO(CH2)4Cl在室温碱性条件下发生取代反应6小时，再将上述加成反应与取代反应循环一次，制备下图中R6为-(CH2)4-，n为2的式X所示产物。聚合物的重均分子量为3109。
2)制备正极浆料：
将正极活性材料碳包覆处理的磷酸铁锂(LFP@C)、导电剂炭黑(SP)、粘结剂聚偏氟乙烯(PVDF)、分散剂(上述聚合物)按照96.5：2：1：0.5的质量比加入到N-甲基吡咯烷酮(NMP)中，分散剂的质量分数为浆料中干料的0.5％，PVDF的重均分子量为70万。磷酸铁锂的碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比为0.271。
3)制备正极极片：
将正极浆料均匀涂覆在铝箔正极集流体的两个表面上，然后干燥，得到膜层；之后经过冷压、分切，得到正极极片，正极极片的面密度为450mg/1540.25mm2。
4)负极极片的制备
将负极活性材料人造石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC)按照重量比为96：2：1：1溶于溶剂去离子水中，混合均匀后制备成负极浆料；将负极浆料多次均匀涂覆在负极集流体铜箔的两个表面上，经过烘干、冷压、分切得到负极极片。
5)隔离膜
以聚丙烯膜作为隔离膜。
6)电解液的制备
在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)，将有机溶剂碳酸乙烯酯(EC)和碳酸甲乙酯(EMC)按照体积比3/7混合均匀，将LiPF6锂盐溶解于有机溶剂中配置成质量含量12.5％的溶液，得到电解液。
7)二次电池的制备
将实施例1制备的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到裸电芯，给裸电芯焊接极耳，并将裸电芯装入铝壳中，并在80℃下烘烤除水，随即注入电解液并封口，得到不带电的电池。不带电的电池再依次经过静置、热冷压、化成、整形、容量测试等工序，获得实施例1的锂离子电池产品。
实施例2
制备方法与实施例1类似，区别在于改变分散剂的种类，分散剂合成过程前两步和实施例1保持一致，第三步中投入的含氮单体为3-氨基-1-丙烯，分散剂结构式如下，其中R1、R3、R6、n与实施例1保持一致。
实施例3
制备方法与实施例1类似，区别在于改变分散剂的种类，分散剂合成过程前两步和实施例1保持一致，第三步聚合物的制备过程如下：
在第二中间产物中加入丁二烯在100℃反应0.5h后再加入丙烯酰胺，在110℃碱性环境下反应6h后得到聚合物，反应示意图如下图所示，其中R1、R3与实施例1中保持一致，s为3，t为3，衍生自丁二烯的结构单元和衍生自丙烯酰胺的结构单元为无规共聚，
实施例4
制备方法与实施例1类似，区别在于改变分散剂的种类，分散剂合成过程前两步和实施例1保持一致，第三步聚合物的制备过程如下：
在第二中间产物中加入丁二烯在100℃反应0.5h后再加入3-氨基-1-丙烯，在110℃碱性环境中反应6h后得到聚合物，反应示意图如下图所示，其中R1、R3与实施例1中保持一致，s为3，t为3，衍生自丁二烯的结构单元和衍生自3-氨基-1-丙烯的结构单元为无规共聚，
实施例5
制备方法与实施例1类似，区别在于改变分散剂的种类，分散剂合成过程前两步和实施例1保持一致，聚合物的制备过程如下：
在第二中间产物中加入丁二烯在碱性环境下100℃反应6.5h后得到聚合物，反应示意图如下图所示，其中R1、R3与实施例1中保持一致，s+t为6，
实施例6
制备方法与实施例1类似，区别在于分散剂不同，分散剂的制备方法为将实施例1的产物继续与3-氨基-1-丙烯反应，制备端基为氨基的聚合物，结构如下所示，其中R1、R3、R6、n与实施例1中保 持一致，
实施例7
制备方法与实施例1类似，区别在于将实施例1的产物继续与丙烯酰胺反应，制备端基为酰胺基的聚合物，结构如下所示，其中R1、R3、R6、n与实施例1中保持一致。
实施例8-15的制备方法与实施例7类似，区别在于实施例8-11中通过调整聚醚链段的聚合度调控聚合物的重均分子量，实施例12-15中调整分散剂的添加量，保持正极膜层的总质量不变，伴随分散剂质量含量的变化，正极活性材料质量百分含量相应调整，具体参数参见表1。
实施例16的制备方法与实施例3类似，在分散剂制备过程中制备聚合物过程中投入的含有不饱和键的有机单体为m＝4制备的分散剂结构式如下：
其中R1、R3、s、t与实施例3保持一致。
实施例17
实施例17与实施例7制备方法基本相同，区别在于R1制备过 程中投入的单体均是环氧乙烷，因此聚醚链段为聚环氧乙烷。
实施例18
实施例18与实施例7制备方法基本相同，区别在于实施例7中分散剂的锚固基团为亚磷酸酯基团，制备方法与实施例7中分散剂的制备方法基本相同，区别在于在制备过程中初始投入的不是POCl3，而是PCl3，其分散剂结构如下所示，其中R1、R3、R6、n与实施例1中保持一致。
实施例19
实施例19与实施例7制备方法基本相同，区别在于实施例19中R3基团与R1基团相同，均是聚醚链段，其中n2均为12，m2均为13。
分散剂的制备过程与实施例7基本一致，区别在于第二中间产物的制备过程不同，具体如下：
称取1,2丙二醇(环氧乙烷、环氧丙烷单体、POCl3总质量的0.4％)、浓硫酸(总质量的0.3％)固体投进反应釜中关闭反应釜盖并用扳手拧紧固定螺栓。对反应釜进行抽真空处理并用高纯氮气置换3次，依次加入环氧乙烷、环氧丙烷，投入的摩尔比为n2：m2，进行嵌段聚合反应，反应过程压力维持在0.3±0.05MPa，温度维持在115±5℃，反应5h后加入POCl3，二氯甲烷(DCM)以及氢氧化钠，在氮气氛围下115±5℃条件下反应5h时间后加入水在50℃下反应10h生成产物，反应过程示意图如下所示，其中A1为n2为12，m2为13。
将产物以实施例7的相同方法继续反应，接合R2基团，生成含磷聚合物，作为分散剂。
实施例20
实施例20与实施例7制备方法基本相同，区别在于粘结剂PVDF重均分子量为30万；正极活性材料碳包覆处理的磷酸铁锂(LFP@C)、导电剂炭黑(SP)、粘结剂聚偏氟乙烯(PVDF)、分散剂的比例为96：2：1.5：0.5。
实施例21
实施例21中以实施例19中制备的直接作为分散剂，不再接合R2基团。
实施例22
实施例22与实施例19制备方法基本相同，区别在于分散剂制备聚醚链段合成过程中初始投入的不是1,2丙二醇，而是苯酚，催化剂为氢氧化钾，其中A1为n2为12，m2为13，R6为-(CH2)4-，n为2。
具体的，分散剂为：
实施例23
实施例23中以实施例22合成过程中制备的产物直接作为分散剂，具体结构式如下：
实施例24
实施例24与实施例23的制备方法基本相同，区别在于产物的制备过程中最后一步不加入水进行水解，而是加入苯酚在50℃下反应10h生成产物，直接作为分散剂，具体结构式为
实施例25
实施例25与实施例7的制备方法基本相同，区别在于聚醚链段合成过程中初始投入的不是1,2丙二醇，而是苯酚，产物中A1为苯基。
实施例26
实施例26与实施例22的制备方法基本相同，区别在于正极活性材料为碳包覆磷酸锰铁锂，其制备方法具体为：
步骤S1：将689.6g碳酸锰、455.27g碳酸亚铁、4.65g硫酸钴、4.87g二氯化钒加入混料机中充分混合6h。然后将得到的混合物转入 反应釜中，并加入5L去离子水和1260.6g二水合草酸，加热至80℃，以500rpm的转速充分搅拌6h，混合均匀，直至反应终止无气泡产生，得到Fe、Co、和V共掺杂的草酸锰悬浮液。然后将悬浮液过滤，在120℃下烘干，再进行砂磨，得到粒径为100nm的Fe、Co、V和S共掺杂草酸锰颗粒。
步骤S2：取步骤S1中制备的草酸锰1793.1g以及368.3g碳酸锂、1146.6g磷酸二氢铵和4.9g稀硫酸，将它们加入到20L去离子水中，充分搅拌，在80℃下均匀混合反应10h，得到浆料。将浆料转入喷雾干燥设备中进行喷雾干燥造粒，得到粉料。在保护气氛(90％氮气和10％氢气)中，700℃下将所述粉料在辊道窑中进行烧结4h，得到正极活性材料的内核Li0.997Mn0.60Fe0.393V0.004Co0.003P0.997S0.003O4。
步骤S3：选用PEG-3000作为第一碳源，将58.2gPEG-1000溶于500g去离子水中，然后搅拌并充分溶解，得到水溶液。将上述内核材料1571.9g加入到该溶液中，一同搅拌混合6h至混合均匀，经喷雾干燥后进行第一烧结处理，第一烧结处理温度的温度为600℃，第一烧结处理的时间为9h，从而经过第一烧结处理得到第一包覆正极活性材料；
步骤S4：选用葡萄糖作为第二碳源，将37.3g葡萄糖溶于500g去离子水中，然后搅拌并充分溶解，得到葡萄糖水溶液。将步骤S3所得1603.3g第一包覆正极活性材料加入到前述葡萄糖溶液中，一同搅拌混合6h至混合均匀，经喷雾干燥后进行第二烧结处理，第二烧结处理的温度为750℃，第二烧结处理的时间为20h，从而经过第二烧结处理得到正极活性材料。
实施例27-28
实施例27、28与实施例26的制备方法基本相同，区别在于正极活性材料的制备方法有所区别，具体差别参数为：
实施例27中第一碳源PEG-10000，第一烧结温度为500℃，第一烧结处理时间为5h，第二碳源为葡萄糖，第二烧结温度为550℃，第二烧结处理时间为20h。
实施例28中第一碳源PEG-2000，第一烧结温度为660℃，第一烧结处理时间为9h，第二碳源为蔗糖，第二烧结温度为750℃，第二烧结处理时间为6h。
对比例
对比例1-2
对比例1的制备方法与实施例1基本相同，区别在于其中不加入分散剂，
对比例2的制备方法与实施例1基本相同，区别在于其中的分散剂为
其中a为3，b为3。
对比例3
对比例3与实施例26的制备方法基本相同，区别在于对比例3中的分散剂同对比例2。
对比例4
对比例4与实施例27的制备方法基本相同，区别在于对比例4中的分散剂同对比例2。
对比例5
对比例5与实施例28的制备方法基本相同，区别在于对比例5中的分散剂同对比例2。
二、性能测试
1、聚合物的表征
1)重均分子量
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％聚合物溶液，配 置好的溶液静置一天，备用。测试时，先用注射器吸取四氢呋喃，进行冲洗，重复几次。然后吸取5ml实验溶液，排除注射器中的空气，将针尖擦干。最后将试样溶液缓缓注入进样口。待示数稳定后获取数据。
2、正极活性材料
1)碳包覆层中碳原子杂化形态的测定：
碳包覆层中碳原子杂化形态的测定：本测试通过拉曼(Raman)光谱进行。通过对Raman测试的能谱进行分峰，得到Ig/Id，其中Id为sp3形态碳的峰强度，Ig为sp2形态碳的峰强度，从而确认两者的摩尔比。
2)碳包覆层厚度测试
碳包覆层的厚度大小测试通过FIB从前述制得的正极活性材料单个颗粒中间切取100nm左右厚度的薄片，然后对薄片进行TEM测试，得到TEM测试原始图片，保存原始图片格式(xx.dm3)。将上述TEM测试所得原始图片在Digital Micrograph软件中打开，通过晶格间距和夹角信息，识别出碳包覆层，量取碳包覆层的厚度。对所选颗粒测量三个位置处的厚度，取平均值。
3、正极浆料
1)浆料最大固含量
正极浆料的最大固含量是指满足出货粘度介于4000～35000mPa.s时且浆料静置24h后不发生凝胶现象的浆料最大固含量。浆料固含量测试方法：取浆料重量记为m0，放置于失重率测试仪器；浆料蒸发溶剂至失重率低于0.3％，记剩余重量为m1；固含量＝m1/m0*100％。
2)过滤时间
取面积30×30cm2的200目滤网折叠成漏斗状；取两只烧杯，一只置于桌面，一只装满500ml浆料倒入滤网漏斗中，记录滴落浆料300ml的过滤时间。
4、正极极片
1)极片脆性测试
取无缺陷的、压实密度为2.6g/cm3的正极极片，沿纵向裁剪成长*宽为25cm*4cm宽的样品，样本数≥4片，先将其按纵向方向(25cm方向)进行预对折后，将膜片放置于测试平台，用2kg的圆筒压辊进行辊压1次。若透光，则脆性透光次数为1次。若不透光则重复反向对折辊压。将折痕对光观察，观察是否透光或断裂，记录实际对折次数，取平均数作为测试结果。
5、二次电池
1)最大体积能量密度
最大体积能量密度是指正极极片处于极限压实密度下测量得到的电池体积能量密度。定义极片的延展率为6‰时或者极片柔韧性折叠次数为2次时对应的压实密度的较小者为极限压实密度。
电池单体的放电能量测量方法如下：
将电池单体在25℃静置2h，确保电池单体的温度为25℃。在25℃下以0.33C将电池单体充电至充电截止电压后，继续以该充电截止电压进行恒压充电，直至电流为0.05C，充电截止(其中，C表示电池单体额定容量)。将电池单体在25℃静置1h后，在25℃下以0.33C将电池单体放电至放电截止电压，记录电池单体放出的总放电容量C0，总放电能量为E0。
电池单体体积测量方法如下：
量取电池单体长宽高，以计算电池单体体积数值M0。
电池能量密度计算公式如下：
电池能量密度＝电池单体放电能量E0/电池单体体积M0。
2)25℃下40圈时的循环容量保持率
电压标定方法如下：
将电池单体在25℃静置2h，确保电池单体的温度为25℃。在25℃下以0.33C0将电池单体充电至4.25V，以4.25V恒压充电至电流为0.05C0后静置1h。在25℃下以0.33C0放电0.95C0，记录此时电压V1。静置5min后在25℃下以0.33C0放电至2.0V。静置5min后，在25℃下以0.33C0将电池单体充电0.97C0，记录此时电压V2。
循环测试流程如下：
将电池单体在25℃静置2h，确保电池单体的温度为25℃。在25℃下以0.33C0将电池单体充电至电压V2后静置0.5h。在25℃下以0.33C0将电池单体放电至电压V1，记录此时容量为Cn。静置0.5h后重复前述步骤至循环圈数n为40cls。
按以上步骤循环40cls后记录Cn/C0为循环容量保持率，作为评估电池循环性能的指标。
3)全电池循环圈数测试：
在45℃的恒温环境下，在2.5V-4.3V下，将全电池按照1C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA。静置5min，然后按照1C放电至2.5V，记录此时的放电容量为D0。重复前述充放电循环，直至放电容量降低到D0的80％。记录此时电池经过的循环圈数。
三、各实施例、对比例测试结果分析
表1
由实施例与对比例的对比可见，实施例中均包括式I所示的聚合物分散剂，其能够在有效提高浆料的最大固含量、缩短过滤时间、提高极片生产效率和质量的同时改善极片的柔性。
由实施例1-4与实施例5的对比可见，R2的有机链段中包含酰胺基团、氨基中至少一种能够进一步提高浆料的最大固含量。
由实施例6-7与实施例1的对比可见，R2的端基包含-C(O)-NH2、-CH2-NH2的至少一种相比于其他端基能够更有效地发挥聚合物的分散作用，提高浆料最大固含量。
由实施例7与实施例17的对比可见，R1、R3中至少一者包含聚(环氧乙烷-环氧丙烷)聚醚链段相比于聚环氧乙烷聚醚链段能够更有效地发挥分散增柔作用，进一步改善浆料最大固含量和极片柔性。
由实施例19与实施例7的对比可见，R1和R3均为聚醚链段相比于二者中只有一者为聚醚链段，能够进一步减少浆料过滤时间，提高极片柔性。
由实施例7-11的对比可见，聚合物的重均分子量为2000-5000能够进一步发挥分散效用，提高浆料最大固含量、缩短过滤时间。
表2
由实施例22与实施例19的对比、实施例25与实施例7、实施例23与实施例21的对比可见，聚醚链段的端基包括苯基，能够进一步提高浆料的分散性。
表3
由实施例12-15可见，基于正极浆料的干料总质量计，聚合物的质量含量为0.1％-2.0％，浆料具有高的最大固含量、低的过滤时间以及高的柔性。基于正极浆料的干料总质量计，聚合物的质量含量为0.2％-1.0％时，能够进一步兼顾极片的加工性能和电池的能量密度。
表4
由实施例7与实施例20的对比可见，正极浆料中包括重均分子量不小于70万的偏氟乙烯聚合物作为粘结剂，能够进一步减少粘结剂用量，提高极片柔性。
表5
由实施例7与实施例18的对比可见，磷酸酯类聚合物相比于亚磷酸酯类聚合物能够更加有效地提升浆料固含量，缩短过滤时间，改善极片柔性；且磷酸酯类聚合物具有更好的稳定性，在提升浆料分散性的基础上还能够有效提高电池的循环容量保持率。
表6
由实施例26-28与对比例3-5的对比可见，本申请实施例提供的聚合物能够更有效地提高碳包覆层有序度高的正极活性材料的分散性，通过分散剂与正极活性材料表面包覆层的匹配同步提高电池的加工性、循环稳定性与克容量。
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 (33)

  1. 一种聚合物，其中，所述聚合物包含式Ⅰ所示的结构，
    其中X包括磷酸酯基或亚磷酸酯基，R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段；R2包含有机链段。
  2. 根据权利要求1所述的聚合物，其中，R2的有机链段中包含酰胺基团、氨基、芳基中的至少一种。
  3. 根据权利要求1或2所述的聚合物，其中，R2的有机链段中还包括C2-12烃基。
  4. 根据权利要求1至3中任一项所述的聚合物，其中，R2包含式II所示的结构
    其中，R4与R5无规共聚，R4包括C2-12亚烃基、C3-13酰胺基中的至少一种，R5包括
    中的至少一种；
    其中，q1、q2、q3、q4各自独立地包括0-4之间的任意整数，R6 a、R6 b包含氢、C1-4烷基中的至少一种，1≤s≤6，1≤t≤10。
  5. 根据权利要求1至4中任一项所述的聚合物，其中，R2包含式III所示的结构
    其中，R6包括C2-12亚烃基，R7包括中 的至少一种；其中,q5、q6各自独立地包括0-4之间的任意整数，1≤n≤6。
  6. 根据权利要求1至5中任一项所述的聚合物，其中，R2的端基包含-C(O)-NH2、-CH2-NH2的至少一种。
  7. 根据权利要求1至6中任一项所述的聚合物，其中，R1、R3中至少一者包含聚醚链段，可选地，R1和R3中均包括聚醚链段。
  8. 根据权利要求1至7中任一项所述的聚合物，其中，R1、R3中至少一者包含式IV所示的聚醚链段
    其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤50，4≤n1≤50。
  9. 根据权利要求1至8中任一项所述的聚合物，其中，所述聚醚链段的端基包括芳基。
  10. 根据权利要求1至9中任一项所述的聚合物，其中，X包括磷酸酯基。
  11. 根据权利要求1至10中任一项所述的聚合物，其中，所述聚合物包括下式所示聚合物的至少一种：

    其中，R1、R3中至少一者包含式IV所示的嵌段共聚聚醚链段
    其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤50，4≤n1≤50，R6、R4各自独立地包括C4-8亚烷基、C4-8亚烯基中的至少一种。
  12. 根据权利要求11所述的聚合物，其中，所述聚醚链段的端基包括芳基。
  13. 根据权利要求1至10中任一项所述的聚合物，其中，所述聚合物如下式所示：
    其中，R2包括氢、芳基、取代或未取代的烷基、含有氨基或酰胺基的有机链段中的至少一种，
    R1、R3中至少一者包含式IV所示的嵌段共聚聚醚链段
    其中EO表示-CH2-CH2-O-，PO表示-CH(CH3)-CH2-O-，4≤m1≤50，4≤n1≤50，且所述聚醚链段的端基包括苯基。
  14. 根据权利要求1至13中任一项所述的聚合物，其中，所述聚合物的重均分子量为1000-10000，可选为2000-5000。
  15. 一种聚合物的制备方法，其中，所述制备方法包括：
    将式VI所示化合物与R3OH、R1OH、水、含有不饱和键的聚合单体反应制备包含式Ⅰ所示结构的聚合物，
    其中，X包括磷酸酯基或亚磷酸酯基，X1、X2、X3均包含卤素；R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段；R2包括有机链段。
  16. 根据权利要求15所述的制备方法，其中，所述制备方法包括以下步骤：
    将式VI所示化合物与R3OH、R1OH、水进行第一反应制备式VII所示的中间产物，
    将所述中间产物与包含含有不饱和键的酰胺、含有不饱和键的胺中的至少一种的聚合单体进行第二反应制备所述聚合物。
  17. 根据权利要求16所述的制备方法，其中，所述第二反应具 体包括以下步骤：
    所述中间产物与含有不饱和键的酰胺、含有不饱和键的胺中的至少一种加成反应后，再与卤素取代的有机醇发生取代反应；
    将上述加成反应和取代反应顺序循环多次后制备所述聚合物；
    其中，R2包含式III所示的结构
    其中，R6包括C2-12烃基，R7包括中的至少一种；其中,q5、q6各自独立地包括0-4之间的任意整数，1≤n≤6。
  18. 根据权利要求16所述的制备方法，其中，所述制备方法还包括以下步骤：
    所述中间产物与(i)含有不饱和键的酰胺、含有不饱和键的胺中的至少一种、(ii)含有不饱和键的烃类单体、环酰胺单体中的至少一种进行第三反应制备所述聚合物，其中，R2包含式II所示的结构：
    其中，R4与R5无规共聚，R4包括C2-12烃基、C3-13酰胺基中的至少一种，R5包括
    中的至少一种；
    其中，q1、q2、q3、q4各自独立地包括0-4之间的任意整数，R6 a、R6 b包含氢、C1-4烷基中的至少一种，1≤s≤6，1≤t≤10。
  19. 一种聚合物的制备方法，其中，所述制备方法包括：
    将式VI所示化合物与包含R3OH、R1OH在内的原料反应制备包含式Ⅰ所示结构的聚合物，
    其中，X包括磷酸酯基或亚磷酸酯基，X1、X2、X3均包含卤素；R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段，所述聚醚链段的至少一者的端基包括芳基；R2包括有机链段。
  20. 权利要求1至14中任一项所述的聚合物或权利要求15至19中任一项所述的制备方法制备的聚合物作为分散剂的用途。
  21. 一种正极浆料，其中，包括分散剂，所述分散剂包括权利要求1至14中任一项所述的聚合物或权利要求15至19中任一项所述的制备方法制备的聚合物。
  22. 根据权利要求21所述的正极浆料，其中，所述正极浆料中包括正极活性材料，所述正极活性材料包括含锂磷酸盐及其碳改性材料的至少一种；可选地，所述正极活性材料包括磷酸铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料、磷酸铁锂及其掺杂材料的碳包覆材料、磷酸锰铁锂及其掺杂材料的碳包覆材料的至少一种。
  23. 根据权利要求21或22所述的正极浆料，其中，所述正极活性材料包括内核以及碳包覆层，所述碳包覆层至少覆盖所述内核的部分表面，其中，所述碳包覆层中sp2杂化碳原子与sp3杂化碳原子的摩尔比不小于0.2，可选为不小于0.5，可选为不小于0.8。
  24. 根据权利要求23所述的正极浆料，其中，所述碳包覆层的厚度不大于15nm；可选地，所述碳包覆层的厚度不大于10nm，可选地，所述碳包覆层的厚度为4nm-8nm。
  25. 根据权利要求21至24中任一项所述的正极浆料，其中，基 于所述正极浆料的干料总质量计，所述聚合物的质量含量为0.1％-2.0％，可选为0.2％-1.0％。
  26. 根据权利要求21至25中任一项所述的正极浆料，其中，所述正极浆料包括粘结剂，所述粘结剂包括重均分子量不小于30万的偏氟乙烯聚合物，可选地，所述粘结剂的重均分子量为70万-900万。
  27. 根据权利要求21至26中任一项所述的正极浆料，其中，所述正极浆料的最大固含量不低于60％，可选为60％-80％。
  28. 一种正极极片，其中，所述正极极片包括正极膜层，所述正极膜层是通过权利要求21至27中任一项所述的正极浆料制备的或者所述正极膜层中包括分散剂，所述分散剂包括权利要求1至14中任一项所述的聚合物或权利要求15至19中任一项所述的制备方法制备的聚合物。
  29. 根据权利要求28所述的正极极片，其中，所述正极极片在压实密度为2.6g/cm3时的可对折次数不小于2次，可选为3-6次。
  30. 根据权利要求28或29所述的正极极片，其中，所述正极极片的面密度不低于300mg/1540.25cm2，可选为300mg/1540.25cm2-600mg/1540.25cm2。
  31. 根据权利要求28至30中任一项所述的正极极片，其中，所述正极膜层包括分散剂，所述分散剂包含式Ⅰ所示的结构，
    其中X包括磷酸酯基或亚磷酸酯基，R1、R3各自独立地包含聚醚链段、聚酯链段、氢、烃基中的至少一种，且R1、R3中至少一者包含聚醚链段或聚酯链段，R2包含有机链段；可选地，R2的有机链段中包含酰胺基团、氨基中的至少一种，可选地，所述聚醚链段的端基包括芳基；
    所述正极活性材料包括磷酸铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料、磷酸铁锂及其掺杂材料的碳包覆材料、磷酸锰铁锂及 其掺杂材料的碳包覆材料的至少一种；可选地，所述正极活性材料包括磷酸锰铁锂及其掺杂材料、磷酸锰铁锂及其掺杂材料的碳包覆材料的至少一种；
    基于所述正极膜层的总质量计，所述分散剂的质量含量为0.1％-2.0％，可选为0.2％-1.0％。
  32. 一种二次电池，其中，包括权利要求28至31中任一项所述的正极极片。
  33. 一种用电装置，其中，包括权利要求32所述的二次电池。
PCT/CN2024/095211 2023-08-01 2024-05-24 聚合物、其制备方法、正极极片、二次电池、用电装置 Ceased WO2025025762A1 (zh)

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