WO2023092389A1 - 正极浆料、正极极片及包括所述正极极片的二次电池 - Google Patents

正极浆料、正极极片及包括所述正极极片的二次电池 Download PDF

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WO2023092389A1
WO2023092389A1 PCT/CN2021/133144 CN2021133144W WO2023092389A1 WO 2023092389 A1 WO2023092389 A1 WO 2023092389A1 CN 2021133144 W CN2021133144 W CN 2021133144W WO 2023092389 A1 WO2023092389 A1 WO 2023092389A1
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positive electrode
positive
pole piece
electrode slurry
structural unit
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PCT/CN2021/133144
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English (en)
French (fr)
Inventor
吴启凡
张明
刘亚成
尹子伊
张铜贤
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宁德时代新能源科技股份有限公司
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Priority to EP21955260.1A priority Critical patent/EP4213234A1/en
Priority to KR1020237009565A priority patent/KR20230079042A/ko
Priority to PCT/CN2021/133144 priority patent/WO2023092389A1/zh
Priority to CN202180091168.6A priority patent/CN116745937A/zh
Priority to JP2023518510A priority patent/JP2024500202A/ja
Priority to US18/120,438 priority patent/US20230231137A1/en
Publication of WO2023092389A1 publication Critical patent/WO2023092389A1/zh

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    • H—ELECTRICITY
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    • 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
    • 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
    • C08G65/04—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 only
    • C08G65/06—Cyclic ethers having no atoms other than carbon and hydrogen outside the ring
    • C08G65/14—Unsaturated oxiranes
    • 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
    • C08G65/04—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 only
    • C08G65/22—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring
    • C08G65/24—Epihalohydrins
    • 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
    • C08G65/321—Polymers modified by chemical after-treatment with inorganic compounds
    • C08G65/327—Polymers modified by chemical after-treatment with inorganic compounds containing phosphorus
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    • H01M10/00—Secondary cells; Manufacture thereof
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    • H01M10/052—Li-accumulators
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    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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    • 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
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • 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
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
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    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
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    • 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 lithium batteries, in particular to a positive electrode sheet comprising polyether phosphate.
  • the present application also relates to a secondary battery including the positive electrode sheet, a battery pack, a battery module, and an electrical device including the secondary battery.
  • lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, Military equipment, aerospace and other fields. Due to the great development of lithium-ion batteries, higher requirements have been put forward for the improvement of its energy density and the reduction of cost.
  • one of the effective ways to increase the energy density of lithium-ion batteries is to increase the coating weight of the positive electrode sheet.
  • increasing the coating weight of the positive electrode sheet will lead to serious risks in the manufacture of the electrode sheet. Since the characteristics of the positive electrode slurry and the electrode sheet directly affect the production of the battery cell, increasing the coating weight of the positive electrode sheet will also make it difficult to manufacture the battery cell.
  • the positive electrode sheet still needs to be improved.
  • the present application is made in view of the above problems, and its purpose is to provide a positive electrode slurry containing a specific polyether phosphate and a positive electrode sheet prepared using the positive electrode slurry or a positive electrode sheet including the positive electrode slurry .
  • the first aspect of the present application provides a positive electrode slurry, which includes a positive electrode active material and a polyether phosphate, wherein the polyether phosphate includes at least the following structural units:
  • A is hydrogen, halogen or haloalkyl, said halogen may be fluorine, chlorine or bromine, said A may be hydrogen or fluoromethyl;
  • B is hydroxyl, R, OR, or ROR', wherein each of R and R' is independently a linear or branched chain alkyl group containing 1 to 8 carbons; optionally, B is methyl, ethyl or ethoxy methyl group;
  • E is phenyl, alkyl-substituted phenyl, ether-substituted phenyl or halogenated phenyl, and E can be phenyl or fluorophenyl.
  • the energy density of the obtained lithium ion battery is significantly improved.
  • the consumption of the electric core can be saved, thereby reducing the total material cost of the electric core.
  • the polyether phosphate has a number average molecular weight ranging from 10,000 to 80,000, an optional range of 10,000 to 60,000, and a more optional range of 30,000 to 50,000.
  • the molecular weight is too small, the stability of the positive electrode slurry is poor, physical gelation is prone to occur, and the resistance of the positive electrode sheet will deteriorate, which will also have a negative impact on battery performance. If the molecular weight is too large, it is not conducive to the dispersion of polyether phosphate in the positive electrode slurry. Therefore, the number average molecular weight of the polyether phosphate must be controlled within the above range.
  • the molar proportion of the structural unit (I) is 0-75 mol%, and the molar proportion of the structural unit (II) is 0-65 mol%,
  • the molar proportion of the structural unit (III) is 5-65 mole %, and the molar proportion of the structural unit (IV) is 4-15 mole %, wherein the molar proportions of the structural unit (I) and the structural unit (II) are different to zero.
  • the molar ratio of the above structural units (I)-(IV) can ensure that sufficient hydrogen bonds and a suitable amount of covalent bonds are formed between the obtained polyether phosphate and the positive electrode active material, current collector, etc., thereby ensuring that the positive electrode
  • the weight ratio of the polyether phosphate to the positive electrode active material is 0.0005-0.030, the optional range is 0.001-0.02, the more optional range is 0.001-0.01, and the most optional range is 0.001-0.01. 0.007.
  • the positive electrode sheet When the ratio is too small, the positive electrode sheet will crack at high coating weight, and when the ratio is too large, it will have an adverse effect on battery performance.
  • the positive electrode active material is selected from lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickel oxide, or mixtures thereof at least one of .
  • the positive electrode active material is at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickelate or their mixtures
  • add the The polyether phosphate ester can better achieve the effects of improving the flexibility of the pole piece and increasing the maximum coating weight of the pole piece.
  • the gel state factor G of the positive electrode slurry ranges from 0 to 1, and the optional range is 0 to 0.3,
  • G (m1-m2)/m1
  • G>0.3 it is judged as gelled
  • m1 is the quality of the positive electrode slurry obtained after filtering 2kg of the initial positive electrode slurry for 10 minutes with a 100-mesh filter screen
  • m2 is the quality of the positive electrode slurry obtained after filtering 2 kg of the positive electrode slurry placed for 48 hours for 10 minutes by using a 100 mesh filter screen, wherein,
  • the positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are the same batch of positive electrode slurry.
  • the gel performance of the positive electrode slurry described in this application is very good.
  • the second aspect of the present application provides a positive pole piece, which includes
  • the positive electrode film layer located on at least one surface of the positive electrode current collector, the positive electrode film layer comprising the positive electrode slurry described in the first aspect of the present application.
  • the present application allows for an increase in the maximum coat weight on the positive electrode sheet by adding the polyether phosphate. This is also manifested in an increase in the maximum weight of the positive electrode film layer.
  • the mass of the positive film layer on the positive sheet per unit area is in the range of 13-43 mg/cm 2 , an optional range of 22-31 mg/cm 2 , and a more optional range of 22-29 mg/cm 2 , the mass is the mass of the positive film layer on a single surface of the pole piece.
  • the mass range of the positive electrode film layer on the positive sheet per unit surface is twice the above range, that is, the range is 26-86mg/cm 2 , and the optional range is 44- 62mg/cm 2 , a more optional range is 44-58mg/cm 2 , the mass is the mass of the positive film layers on both surfaces of the pole piece.
  • the weight of the positive electrode film layer on the active sheet per unit surface is too small, the uniformity of the electrode sheet is poor; when the weight of the positive electrode film layer on the active sheet per unit surface is too large, the electrode sheet coating process is severely cracked and production cannot continue.
  • the weight of the positive electrode film layer on the positive sheet per unit area is limited within the above range to ensure that the best effect can be achieved within this range.
  • the positive electrode sheet described in this application has very good flexibility and significantly improved coating weight. Applying the positive electrode sheet to a secondary battery, for example, directly adding it to the positive electrode slurry during preparation can significantly increase the energy density of the battery.
  • the positive electrode film layer includes two sublayers, the sublayers are parallel to the positive electrode current collector and stacked on each other, wherein the polyether phosphoric acid in the sublayer closest to the positive electrode current collector.
  • the ratio of the weight content of the ester to the weight content of the polyether phosphate in the sublayer farthest from the positive current collector is in the range of 0-60, and the optional range is 0.1-30.
  • the positive pole piece does not produce cracks, or,
  • the cold pressing pressure can be reduced, thereby reducing cracks, reducing the risk of broken belts, and further improving the flexibility of the pole piece.
  • the increase rate I of the wetting rate of the positive pole piece ranges from 2 to 20%, and the optional range is 6 to 15%.
  • I2 is the infiltration rate of the positive pole piece in the electrolyte
  • I1 is the infiltration rate of the positive electrode sheet not including the polyether phosphate in the electrolyte
  • the positive electrode sheet used when measuring I1 is the same as the positive electrode sheet used when measuring I2, the difference is only that the polyether phosphate is not included in the positive electrode sheet used when measuring I1, and used when measuring I2
  • the positive electrode sheet contains the polyether phosphate.
  • the wettability of the pole piece is good, which can achieve good wetting and liquid retention of the electrolyte, so as to realize the effective infiltration of the pole piece of the battery, avoid insufficient wetting of the pole piece, improve the efficiency of the liquid injection of the battery cell and the stability of the pole piece during the cycle. wettability, thereby effectively improving the performance of battery products.
  • the wettability of the positive electrode sheet described in the present application in the electrolyte is very good.
  • a third aspect of the present application provides a secondary battery, which includes the negative electrode sheet described in the first aspect of the present application.
  • a fourth aspect of the present application provides a battery module, which includes the secondary battery described in the second aspect of the present application.
  • a fifth aspect of the present application provides a battery pack, which includes the battery module described in the third aspect of the present application.
  • the sixth aspect of the present application provides an electric device, which includes the secondary battery described in the third aspect of the present application, the battery module described in the fourth aspect of the present application, or the battery pack described in the fifth aspect of the present application. at least one.
  • Fig. 1 is a schematic diagram of the principle of interaction between polyether phosphate in the positive pole piece of the present application and other substances in the positive pole piece, wherein the polyether phosphate is the polyether phosphate described in the present application.
  • Fig. 2 is a schematic diagram of the process of coating cracking caused by capillary tension during the coating process of the positive electrode sheet in the prior art, wherein the active material is the positive active material, and the force is the force during the coating process,
  • the polyether phosphates described in this application are not used therein.
  • Figure 3 is a schematic diagram of the positive electrode sheet described in the present application without cracking during the coating process, wherein the active material is the positive active material, the force is the force in the coating process, and the polymer described in the application is used. ether phosphate.
  • Figure 4 is a schematic diagram of the increase in the maximum coating weight per unit area in the positive electrode sheet after using the polyether phosphate of the present application, wherein the positive electrode material represents the positive electrode active material material, SP represents the conductive agent used in the positive electrode sheet, and PVDF represents the positive electrode The binder used in the pole piece; Wherein X represents the maximum coating thickness of the positive electrode slurry that does not contain polyether phosphate, and Y represents the maximum coating thickness of the positive electrode slurry that includes polyether phosphate under the same conditions, very Obviously, Y is greater than X.
  • FIG. 5 is a schematic diagram of a rolling needle used in the flexibility test of the positive electrode sheet of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-6.
  • the numerical range "a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • step (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • the inventors of the present application designed and synthesized a flexible polymer material polyether phosphate, by adding the flexible material to increase the coating weight, improve the coating quality, and eliminate the risks caused by cold pressing and winding processes problem while reducing the overall cost of materials used to manufacture the battery.
  • the first aspect of the present application provides a positive electrode slurry, which includes a positive electrode active material and a polyether phosphate, and the polyether phosphate includes at least the following structural units:
  • A is hydrogen, halogen or haloalkyl, said halogen may be fluorine, chlorine or bromine, said A may be hydrogen or fluoromethyl;
  • B is hydroxyl, R, OR, or ROR', wherein each of R and R' is independently a linear or branched chain alkyl group containing 1 to 8 carbons; optionally, B is methyl, ethyl or ethoxy methyl group;
  • E is phenyl, alkyl-substituted phenyl, ether-substituted phenyl or halogenated phenyl, and E can be phenyl or fluorophenyl.
  • the structural units (IV) are present as end groups.
  • the polyether phosphate is polymerized from the following components:
  • the molar proportion of component (a) is 0-75 mole %; the molar proportion of component (b) is 0-65 mole % ; The molar proportion of component (c) is 5-65 mole %; The molar proportion of component (d) is 4-15 mole %,
  • component (a) is selected from ethylene oxide, epifluorohydrin, epichlorohydrin, epibromohydrin.
  • component (b) is selected from the group consisting of propylene oxide, ethyl glycidyl ether, isopropyl glycidyl ether, butyl glycidyl ether, isopropyl glycidyl ether, epoxy Butane, 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, 1, 2-epoxy-3-methylbutane, glycidol.
  • component (c) is selected from styrene oxide, phenyl.
  • a C 1-8 alkyl group is a straight chain or branched chain alkyl group containing 1-8 carbons
  • the straight chain or branched chain alkyl group containing 1-8 carbons can be selected from, for example, methyl , ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, 2-methylpentyl base, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl , 3,3-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethyl
  • C 1-8 alkenyl is a straight chain or branched alkenyl group containing 1-8 carbons, which may include, but not limited to, vinyl, propenyl, allyl, 1-methyl prop- 2-en-1-yl, 2-methylprop-2-en-1-yl, but-2-en-1-yl, but-3-en-1-yl, 1-methylbut-3- En-1-yl and 1-methylbut-2-en-1-yl, etc.
  • the alkyl substituent can be straight chain or branched chain alkyl containing 1-8 carbons, which can be optionally selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl base, tert-butyl.
  • the alkyl substitution is mono-substitution or di-substitution.
  • the alkyl-substituted phenyl group can be selected from, for example, 3,4-dimethylphenyl, 2-methylphenyl, 3,5-dimethylphenyl, 4-(2- methylpropyl) phenyl.
  • the alkyl group in the haloalkyl group may be a straight chain or branched chain alkyl group containing 1-8 carbons, for example, the alkyl group in the haloalkyl group may optionally be selected from methyl, ethyl, propane Base, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, 2-methylpentyl, 3-methylpentyl Amylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 3,3- Dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3-ethylpentyl, 2,2,3
  • the ether substituent may be a straight-chain or branched alkoxy group containing 1-8 carbons, optionally selected from methoxy, ethoxy, propoxy or butoxy.
  • the ether-substituted phenyl group may be selected from, for example, 4-methoxyphenyl, 3-methoxyphenyl, and the like.
  • haloalkylphenyl refers to phenyl substituted by haloalkyl, wherein haloalkyl refers to alkyl substituted by halogen, wherein alkyl is C 1-8 alkyl.
  • halophenyl represents phenyl substituted by halogen.
  • halogen may be selected from fluorine, chlorine, bromine, iodine.
  • the halogenated phenyl group can be selected from, for example, 4-fluorophenyl, 2-fluorophenyl, 2,6-difluorophenyl, 4-(trifluoromethyl)phenyl, 4 -chlorophenyl, 3-chlorophenyl, 4-bromophenyl, 3-bromophenyl or 2-bromophenyl.
  • the structural unit (I) (or the structural unit formed by component (a)) in the structural formula (1) of the polyether phosphate described in the application can improve the formation of hydrogen bonds between the polymer and the positive electrode particle surface, conductive carbon, and aluminum foil Ability;
  • Structural unit (II) (or the structural unit formed by component (b)) can prolong the branched chain of molecule, guarantee that described polyether phosphate ester forms covalent bond with positive electrode particle surface, conductive carbon, aluminum foil surface, guarantees The positive electrode particles do not migrate during the coating process;
  • the structural unit (III) (or the structural unit formed by the component (c)) can improve the rigidity of the polyether phosphate, so that it has a certain strength and hardness, thereby improving the polyether phosphate.
  • the phosphate end group acts as an anchor, and can be used as a wetting and dispersing agent to uniformly and stably disperse the positive electrode active component particles in the NMP medium.
  • the polyether phosphate of the present application is a long flexible chain, which can pass through the connection between the structural unit (I) (or the structural unit formed by component (a)) and the positive active material and the positive current collector. Hydrogen bonds can also be formed between the structural unit (II) (or the structural unit formed by the component (b)) and the positive electrode active material and the positive electrode current collector.
  • the structural unit (III) Or the benzene ring in the structural unit formed by component (c) interacts with the surface of the positive electrode active material particle.
  • covalent bonds can also be formed between the polyether phosphates of the present application.
  • the stability of the positive electrode slurry can be improved, the flexibility of the positive electrode sheet can be improved, and the stability of each material in the positive electrode sheet can be guaranteed. Dispersion, so that the coating weight of the positive electrode sheet can be increased.
  • the positive electrode slurry of the present application did not crack during the entire coating process.
  • the maximum coating thickness (weight) in the positive electrode sheet is significantly increased.
  • polyether phosphate described in this application can be obtained according to conventional technical means in the art, and can also be prepared using the following steps:
  • Step 1 Make the alkylene oxide monomer generate polyether under basic conditions, wherein, optionally, the solvent used is one or more in dimethyl sulfoxide, acetone, ether;
  • the basic substances that may be added in the preparation are, for example, NaOH, KOH, dicyclohexylcarbodiimide; optionally, the reaction temperature range of this reaction is 80-160°C, and the reaction time range is 3-7h; optional Optionally, the range of stirring speed during the reaction is 1000-2000 rpm; optionally, after the reaction, a purification step of vacuum distillation is performed.
  • Step 2 React the polyether in step (1) with a phosphating agent to generate polyether phosphate, wherein, optionally, the reaction is carried out in a reactor; optionally, the temperature of the reaction ranges from 60 to 130 °C; optionally, the reaction time range is 2-15h; optionally, stirring is performed during the reaction, the stirring time range is 1-10h, and the stirring speed range is 1000-2000r/min; optionally , after the reaction was completed, a vacuum distillation purification step was carried out.
  • a phosphating agent to generate polyether phosphate
  • the positive electrode slurry described herein has a pH range of about 6-9 at 20-60°C.
  • the pH value is tested according to conventional means in the art.
  • the energy density of the obtained lithium ion battery is significantly improved.
  • the consumption of the electric core can be saved, thereby reducing the total material cost of the electric core.
  • the polyether phosphate has a number average molecular weight ranging from 10,000 to 80,000, an optional range of 10,000 to 60,000, and a more optional range of 30,000 to 50,000.
  • the molecular weight has an influence on the processability of the positive electrode sheet. In the case of a small molecular weight, the flexibility of the positive electrode sheet is not significantly improved, and there will still be cracks in the coating, and there may be problems of cold-pressing tape breakage and winding breakage. If the molecular weight is too small, the stability of the positive electrode slurry is poor, physical gelation is prone to occur, and the resistance of the positive electrode sheet will deteriorate, which will also have a negative impact on battery performance. If the molecular weight is too large, it is not conducive to the dispersion of polyether phosphate in the positive electrode slurry. Therefore, the number average molecular weight of the polyether phosphate must be controlled within the above range.
  • the molar proportion of structural unit (I) is 0-75 mol %
  • the molar proportion of the structural unit (II) is 0-65 mole %
  • the molar proportion of the structural unit (III) is 5-65 mole %
  • the molar proportion of the structural unit (IV) is 4-15 mole %, wherein The molar proportions of structural unit (I) and structural unit (II) are not zero at the same time.
  • the molar proportion of structural unit (I) (or based on the total molar weight of components (a) to (d), group
  • the molar proportion of (a) can be about 0 mol%, about 5 mol%, about 10 mol%, about 14 mol%, about 15 mol%, about 17 mol%, about 20 mol%, about 25 mol% , about 26 mol%, about 27 mol%, about 28 mol%, about 29 mol%, about 30 mol%, about 31 mol%, about 32 mol%, about 33 mol%, about 35 mol%, about 40 mol% , about 42 mol%, about 45 mol%, about 50 mol%, about 55 mol%, about 60 mol%, about 62 mol%, about 65 mol%, about 68 mol%, about 70 mol%, about 72 mol% or about 75 mole percent.
  • the molar proportion of structural unit (II) (or based on the total molar weight of components (a) to (d), group
  • the molar proportion of part (b)) can be about 0 mol%, about 5 mol%, about 10 mol%, about 14 mol%, about 15 mol%, about 17 mol%, about 20 mol%, about 22 mol% , about 25 mol%, about 30 mol%, about 31 mol%, about 35 mol%, about 40 mol%, about 42 mol%, about 43 mol%, about 45 mol%, about 50 mol%, about 52 mol% , about 53 mol%, about 54 mol%, about 55 mol%, about 56 mol%, about 58 mol%, about 60 mol%, about 63 mol%, about 65 mol%.
  • the molar proportion of the structural unit (II) is within any range composed of the above
  • the molar proportion of structural unit (III) (or based on the total molar mass of components (a) to (d), the group The molar proportion of part (c)) is about 5 mol%, about 6 mol%, about 7 mol%, about 9 mol%, about 10 mol%, about 11 mol%, about 15 mol%, about 20 mol%, About 23 mol%, about 24 mol%, about 25 mol%, about 26 mol%, about 30 mol%, about 31 mol%, about 33 mol%, about 35 mol%, about 40 mol%, about 45 mol%, About 50 mole%, about 55 mole%, about 59 mole%, about 60 mole%, about 61 mole%, or about 65 mole%.
  • the molar proportion of the structural unit (III) is within any range composed of the above-mentioned arbitrary values.
  • the molar proportion of structural unit (IV) (or based on the total molar mass of components (a) to (d), the group The molar proportion of (d)) is about 4 mol%, about 5 mol%, about 6 mol%, about 7 mol%, about 8 mol%, about 9 mol%, about 10 mol%, about 11 mol%, About 12 mole%, about 13 mole%, about 14 mole%, or about 15 mole%.
  • the molar proportion of the structural unit (IV) is within any range composed of the above-mentioned arbitrary values.
  • a certain numerical value means a range, that is, the range of ⁇ 3% of the numerical value.
  • the molar ratio of the above structural units (I)-(IV) (or components (a)-(d)) can ensure that sufficient hydrogen bonds are formed between the obtained polyether phosphate and the positive electrode active material, current collector, etc. And an appropriate amount of covalent bonds, thereby ensuring the stability of the positive electrode sheet during the preparation process and ensuring the flexibility of the positive electrode sheet and the dispersibility of various positive electrode materials, thereby improving the energy density of the battery.
  • the weight ratio of the polyether phosphate to the positive electrode active material is 0.0005-0.030, the optional range is 0.001-0.02, the more optional range is 0.001-0.01, and the most optional range is 0.001-0.01. 0.007.
  • the weight ratio of the polyether phosphate to the positive electrode active material is 0.0005 ⁇ 0.030. When the ratio is too small, the positive electrode sheet will crack at high coating weight, and when the ratio is too large, it will have an adverse effect on battery performance.
  • the positive electrode active material is selected from lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium nickel oxide, or mixtures thereof at least one of .
  • the present application can use any positive electrode active material known in the art for batteries.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon At least one of a composite material, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also may be abbreviated as LFP)
  • composite materials of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode active material is lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium nickel-cobalt manganate, lithium nickel-cobalt aluminate, lithium nickelate or a mixture thereof
  • the addition of the polyether phosphate can better achieve the effects of improving the flexibility of the pole piece and increasing the maximum coating weight of the pole piece.
  • the gel state factor G of the positive electrode slurry ranges from 0 to 1, and the optional range is 0 to 0.3,
  • G (m1-m2)/m1
  • G>0.3 it is judged as gelled
  • m1 is the quality of the positive electrode slurry obtained after filtering 2kg of the initial positive electrode slurry for 10 minutes with a 100-mesh filter screen
  • m2 is the quality of the positive electrode slurry obtained after filtering 2 kg of the positive electrode slurry placed for 48 hours for 10 minutes by using a 100 mesh filter screen, wherein,
  • the positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are the same batch of positive electrode slurry.
  • the gel performance of the positive electrode slurry described in this application is very good.
  • the second aspect of the present application provides a positive pole piece, which includes
  • the positive electrode film layer located on at least one surface of the positive electrode current collector, the positive electrode film layer comprising the positive electrode slurry described in the first aspect of the present application.
  • the present application allows for an increase in the maximum coat weight on the positive electrode sheet by adding the polyether phosphate. This is also manifested in an increase in the maximum weight of the positive electrode film layer.
  • the mass of the positive film layer on the positive sheet per unit area is in the range of 13-43 mg/cm 2 , an optional range of 22-31 mg/cm 2 , and a more optional range of 22-29 mg/cm 2 , the mass is the mass of the positive film layer on a single surface of the pole piece.
  • the mass range of the positive electrode film layer on the positive sheet per unit surface is twice the above range, that is, the range is 26-86mg/cm 2 , and the optional range is 44- 62mg/cm 2 , a more optional range is 44-58mg/cm 2 , the mass is the mass of the positive film layers on both surfaces of the pole piece.
  • the maximum coating weight per unit area on the positive electrode sheet can reach 41 mg/cm 2 , optionally, the maximum coating weight per unit area on the positive electrode sheet is It can be in the range of 23-41mg/cm 2 .
  • the weight of the positive electrode film layer on the active sheet per unit surface is too small, the uniformity of the electrode sheet is poor; when the weight of the positive electrode film layer on the active sheet per unit surface is too large, the electrode sheet coating process is severely cracked and production cannot continue.
  • the weight of the positive electrode film layer on the positive sheet per unit area is limited within the above range to ensure that the best effect can be achieved within this range.
  • the positive current collector has two opposite surfaces in its own thickness direction, and the positive electrode film layer is arranged on any one or both of the two opposite surfaces of the positive current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can 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 can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the mass content of the positive active material in the positive film layer is 90-97%, based on the positive film layer. This content can be measured using EDS.
  • the mass content is too small, the prepared battery has low energy density and cannot meet the battery capacity requirement; when the mass content is too large, the binder and the conductive agent are insufficient, resulting in poor battery performance.
  • the mass content of the binder in the positive film layer is 2-5%, based on the total mass of the positive film layer.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the existing conventional positive pole piece uses a binder with a specific crystallinity or similar crystallinity, which is brittle after being coated and dried to form a film. Under the action of stress, the pole piece is easy to crack, while the positive pole piece of this application Using a binder that also has this crystallinity, the pole piece does not crack.
  • 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 in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, are dispersed in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the positive electrode sheet described in this application has very good flexibility, and the coating weight has been significantly improved. Applying the positive electrode sheet to a secondary battery, for example, directly adding it to the positive electrode slurry during preparation can significantly increase the energy density of the battery.
  • the positive electrode film layer includes two sublayers, the sublayers are parallel to the positive electrode current collector and stacked on top of each other, wherein the sublayer closest to the positive electrode current collector (i.e., away from the current collector)
  • the weight content of the polyether phosphate in the sublayer close to the fluid relative to the weight content of the polyether phosphate in the sublayer farthest from the positive current collector (that is, the sublayer far away from the current collector) The ratio ranges from 0 to 60, and the optional range is 0.1 to 30.
  • the weight content of the polyether phosphate in the sublayer closest to the positive electrode current collector is the difference between the weight content of the polyether phosphate in the sublayer farthest from the positive electrode current collector
  • the ratio can be about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 2, about 3, about 4, about 5, about 6, about 7 , about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, about 20, about 21, about 22, about 23, about 24, about 25, about 26, about 27, about 28, about 29, about 30, about 31, about 32, about 33, about 34, about 35, about 36, about 37, about 38, about 39, about 40, About 41, About 42, About 43, About 44, About 45, About 46, About 47, About 48, About 49, About 50, About 51, About 52, About 53, About 54, About 55, About 56, About 57 , about 58, about 59, or about 60.
  • the ratio of the weight content of the polyether phosphate in the sublayer closest to the positive current collector to the weight content of the polyether phosphate in the sublayer farthest from the positive current collector is within any of the above-mentioned any range of values.
  • the weight ratio of the polyether phosphate to the positive electrode active material is 0-0.043; in the sublayer far from the current collector, the polyether phosphate The weight ratio of the ether phosphate to the positive electrode active material is 0.0006 ⁇ 0.004.
  • a positive electrode film layer with two sublayers when preparing a positive electrode film layer with two sublayers, first prepare two positive electrode slurries containing different amounts of polyether phosphate, and then coat one slurry on the current collector and dry it. Apply another coat of slurry and let dry.
  • the positive pole piece does not produce cracks, or,
  • the flexibility of the positive pole piece is measured by a rolling needle
  • a pole piece sample with a length and width of 50mm ⁇ 100mm in length is prepared, and the Coil on the pole piece, and use a combination of visual inspection and a microscope to observe the cracks of the pole piece.
  • the degree of flexibility is judged according to the following method:
  • the diameter of the needle is R,
  • R 6.0mm without cracks
  • R 7.0mm with cracks, which is the fifth grade of flexibility.
  • the preparation method of the needle roll is as follows:
  • the formed hydrogen bonds are broken and the flexible backbone is stretched.
  • the cold pressing pressure can be reduced, thereby reducing cracks and reducing the risk of belt breaking.
  • the increase rate I of the wetting rate of the positive pole piece ranges from 2 to 20%, and the optional range is 6 to 15%.
  • I2 is the infiltration rate of the positive pole piece in the electrolyte
  • I1 is the infiltration rate of the positive electrode sheet not including the polyether phosphate in the electrolyte
  • the positive electrode sheet used when measuring I1 is the same as the positive electrode sheet used when measuring I2, the difference is only that the polyether phosphate is not included in the positive electrode sheet used when measuring I1, and used when measuring I2
  • the positive electrode sheet contains the polyether phosphate.
  • the wettability of the pole piece is good, which can achieve good wetting and liquid retention of the electrolyte, so as to realize the effective infiltration of the pole piece of the battery, avoid insufficient wetting of the pole piece, improve the efficiency of the liquid injection of the battery cell and the stability of the pole piece during the cycle. wettability, thereby effectively improving the performance of battery products.
  • the wettability of the positive electrode sheet described in the present application in the electrolyte is very good.
  • the third aspect of the present application provides a secondary battery, which includes the positive electrode sheet according to the second aspect of the present application, or is prepared using the positive electrode slurry according to the first aspect of the present application.
  • the energy density of the secondary battery described in this application has been significantly improved.
  • the overall cost of materials is reduced when manufacturing the battery.
  • the secondary battery, battery module, battery pack and electric device of the present application will be described below.
  • a secondary battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposing surfaces of the negative electrode current collector.
  • the negative electrode current collector can use a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the negative electrode active material can be a negative electrode active material known in the art for batteries.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, phosphorus-based material, tin-based material, lithium titanate, and the like.
  • the phosphorus-based material may be selected from at least one of elemental phosphorus, phosphorus-oxygen compounds, phosphorus-carbon composites, phosphorus-nitrogen composites, and phosphorus alloys.
  • the tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further optionally include a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may also optionally include a conductive agent.
  • the conductive agent can 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 thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • CMC-Na sodium carboxymethylcellulose
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, conductive agent, 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 current 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 pole piece and the negative pole piece.
  • the present application has no specific limitation on the type of electrolyte, which can be selected according to requirements.
  • the electrolyte may be selected from at least one of solid electrolytes and liquid electrolytes (ie, electrolytic solutions).
  • the electrolyte is an electrolytic solution.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), difluorosulfonyl Lithium amide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium difluorooxalate borate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorooxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium perchlorate
  • the solvent may be selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), Dipropyl Carbonate (DPC), Methyl Propyl Carbonate (MPC), Ethyl Propyl Carbonate (EPC), Butylene Carbonate (BC), Fluoroethylene Carbonate (FEC), Methyl Formate (MF), Methyl Acetate Ester (MA), Ethyl Acetate (EA), Propyl Acetate (PA), Methyl Propionate (MP), Ethyl Propionate (EP), Propyl Propionate (PP), Methyl Butyrate (MB) , ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl s
  • additives are optionally included in the electrolyte.
  • additives can include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of batteries, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature performance. Additives etc.
  • a separator is further included in the secondary battery.
  • the separator is arranged between the positive pole piece and the negative pole piece to play the role of isolation.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • the secondary battery may include an outer package for encapsulating the positive electrode tab, the negative electrode tab, and the electrolyte.
  • the positive pole piece, the negative pole piece and the separator can be laminated or wound to form a stacked structure cell or a wound structure cell, and the cell is packaged in the outer package; the electrolyte can be electrolyte, and the electrolyte can be infiltrated in the cell.
  • the number of cells in the secondary battery can be one or several, and can be adjusted according to requirements.
  • the present application provides an electrode assembly.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer package of the secondary battery may be a soft bag, such as a pouch-type soft bag.
  • the material of the soft bag can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc. can be included.
  • the outer packaging of the secondary battery may be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the present application provides a method for preparing a secondary battery, wherein the negative electrode sheet described in this application or the negative electrode sheet prepared according to the method described in this application is used.
  • the preparation of the secondary battery may also include the step of assembling the negative electrode sheet, the positive electrode sheet and the electrolyte of the present application to form a secondary battery.
  • the positive electrode sheet, the separator, and the negative electrode sheet can be sequentially wound or laminated, so that the separator is placed between the positive electrode sheet and the negative electrode sheet for isolation, and a battery cell is obtained. Put the battery cell in the outer package, inject the electrolyte and seal it to obtain the secondary battery.
  • the preparation of the secondary battery may further include the step of preparing a positive electrode sheet.
  • the positive electrode active material, conductive agent and binder can be dispersed in a solvent (such as N-methylpyrrolidone, referred to as NMP) to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, After drying, cold pressing and other processes, the positive electrode sheet is obtained.
  • NMP N-methylpyrrolidone
  • the preparation of the secondary battery includes the step of preparing a negative electrode sheet according to the method described in this application.
  • the present application has no special limitation on the shape of the secondary battery, which may be cylindrical, square or any other shape.
  • the present application provides an electric device, battery module or battery pack, wherein the electric device, battery module or battery pack includes the secondary battery as described in the present application or the secondary battery described in the present application.
  • the secondary battery prepared by the method.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a device may be a cell phone, tablet, laptop, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • a secondary battery, a battery module or a battery pack can be selected according to its use requirements.
  • the present application provides a battery module including the secondary battery described in the present application.
  • the present application also provides a battery pack, which includes the above-mentioned battery module.
  • the present application further provides an electrical device, which includes at least one of the secondary battery described in the present application, the above-mentioned battery module, or the above-mentioned battery pack.
  • Step 1 Make precursor 1, precursor 2, precursor 3 (see Table 1 for specific types and dosage) to generate polyether under alkaline conditions, and stop the reaction when the number average molecular weight of polyether reaches 2w (ie 20000) ;
  • Step 2 react the polyether prepared in step (1) with the phosphating agent (phosphorus pentoxide) (see Table 1 for specific dosage) to generate polyether phosphate, after the reaction is completed, filter and dialyze to cut off the number average molecular weight It is 2w-3w (ie 20000-30000) polyether phosphate.
  • the phosphating agent phosphorus pentoxide
  • step 1 Mix the positive electrode active material (lithium iron phosphate), conductive agent (conductive carbon black Super P), and binder PVDF (see Table 2 for specific dosage) for 30 minutes. The resulting mixture was then added to NMP and stirred for 180 min to disperse it evenly. Finally, the polyether phosphate prepared in step 1 was added, and then fully stirred for 60 minutes to form a uniform positive electrode slurry.
  • positive electrode active material lithium iron phosphate
  • conductive agent conductive carbon black Super P
  • binder PVDF see Table 2 for specific dosage
  • the positive electrode slurry is coated on the surface of the aluminum foil of the positive electrode current collector, and the electrode sheet is dried and cold pressed to obtain the positive electrode sheet.
  • After a series of positive pole piece performance tests (mainly (1) test whether the pole piece is cracked when coated, (2) whether it breaks after cold pressing, (3) carry out the flexibility test method of the positive pole piece described herein, flexibility
  • the maximum coating weight per unit area is the maximum coating weight per unit area without cracking during coating or breaking after cold pressing), and the maximum coating weight per unit area is 41mg/cm 2 .
  • Negative electrode active material graphite
  • conductive agent Super P
  • binder SBR
  • thickener CMC
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • PE film Polyethylene (PE) film is used.
  • the above-mentioned positive pole piece, separator, and negative pole piece are stacked in order, and the electrode assembly is obtained after winding.
  • the electrode assembly is packed into the outer package, the above-mentioned electrolyte is added, and the process of packaging, standing, forming, aging, etc. After that, the secondary battery of Example 1 was obtained.
  • the outer package is a hard shell case with a length ⁇ width ⁇ height of 148mm ⁇ 28.5mm ⁇ 97.5mm.
  • Example 1 for the preparation process of steps 1 and 4-7, the cut-off range of the number average molecular weight of polyether phosphate is shown in Table 8, and the preparation process of steps 2-3 is changed as follows:
  • Step 2 Preparation of cathode slurry
  • Example 21 The difference from Example 21 is that the positive electrode slurry 1 does not contain polyether phosphate, and other preparation processes are similar to Example 21.
  • specific method parameters refer to Table 1 and Table 3, and the intercepted number average molecular weight range is shown in Table 7.
  • the preparation process is similar to that of Example 21, except that the raw materials and amounts shown in Table 1 and Table 3 are used and the number average molecular weight is cut off as shown in Table 8.
  • the positive electrode slurry is coated on both surfaces of the positive electrode current collector, that is, double-sided coating.
  • Example 13 The precursors 1-3 and phosphating agents used in Examples 13-26 are the same as those in Example 1.
  • the gel state of the positive electrode slurry was evaluated by the following method:
  • m1 is the quality of the positive electrode slurry obtained after filtering 2kg of the initial positive electrode slurry for 10 minutes with a 200-mesh filter screen
  • m2 is the quality of the positive electrode slurry obtained after filtering 2 kg of positive electrode slurry placed for 48 hours for 10 minutes using a 200-mesh filter screen, wherein,
  • the positive electrode slurry used when measuring m1 and the positive electrode slurry used when measuring m2 are the same batch of positive electrode slurry.
  • G in the range of 0-0.3 is judged as no gel; G>0.3 is judged as gel.
  • the flexibility of the positive pole piece is evaluated by rolling a needle, and the test method is as follows:
  • the degree of flexibility is judged according to the following method:
  • the diameter of the needle is R,
  • R 6.0mm without cracks
  • R 7.0mm with cracks, which is the fifth grade of flexibility.
  • I2 is the infiltration rate of the positive pole piece in the electrolyte
  • I1 is the infiltration rate of the positive electrode sheet not including the polyether phosphate in the electrolyte
  • the positive electrode sheet used when measuring I1 is the same as the positive electrode sheet used when measuring I2, the difference is only that the polyether phosphate is not included in the positive electrode sheet used when measuring I1, and used when measuring I2
  • the positive electrode sheet contains the polyether phosphate.
  • the capillary method was used to test the liquid absorption rate of the pole piece.
  • the liquid level of the capillary drops, record the time with a stopwatch.
  • When the liquid level drops read the time of the washing solution and record the data t.
  • the infiltration rate of the electrolyte is equal to
  • the "single-side” refers to coating on only one surface of the current collector, which is not the same concept as the number of layers of the "sub-layer” mentioned in this application.
  • the maximum coating weight per unit area in the table refers to the weight per side.
  • the coating weight data in the table examples of this application all refer to the data of the maximum coating weight per unit area of a single surface, and the performance of the electrode sheet and the battery performance are measured at the maximum coating weight.
  • the maximum coating weight per unit area refers to whether (1) cracking during the process of testing the coated pole piece (2) whether it breaks during cold pressing, (3) after the flexibility test of the positive pole piece described in this application, the flexibility The maximum coating weight below the second grade without cracking during coating and without breaking after cold pressing.
  • the batteries prepared in Examples and Comparative Examples were weighed to obtain the mass of the entire battery; after capacity formation of the battery, the battery was left to stand at 25°C for 10 minutes and then charged to 100% SOC at 0.33C, depolarized with a small current and then statically Set it for 10 minutes, and then discharge it at 0.33 to 0% SOC, and the obtained capacity is the 0.33C capacity of the battery.
  • (I)/(II)/(III)/(IV) means structural unit (I) molar weight/structural unit (II) molar weight/structural unit (3) molar weight/structural unit (IV) molar weight, wherein structural unit (I) molar weight is corresponding to the molar weight of precursor 1 in each embodiment; Structural unit (II) molar weight is corresponding to the molar weight of precursor 2 in each embodiment; Structural unit ( 3) The molar weight corresponds to the molar weight of the precursor 3 in each embodiment; the molar weight of the structural unit (IV) corresponds to the molar weight of the phosphate group in each embodiment.
  • the coating weight per unit area is basically the same in the examples, the battery energy density corresponding to the positive pole sheet with two sublayers is relatively high; further, the sublayer closest to the positive current collector
  • the ratio of the weight content of the polyether phosphate in the layer to the weight content of the polyether phosphate in the sublayer farthest from the positive electrode current collector is within the range of 0 to 60, when the ratio > 60 (Example 26 ), which affects the stability of the slurry and the sheet resistance of the pole piece, and the DCR of the battery cell is relatively large.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

提供一种包括聚酰磷酸酯的正极浆料，聚酰磷酸酯至少包括如下结构单元:以及结构单元（IV）磷酸酯基团，A为氢、卤素或卤代烷基；B%羟基、R、0R,或ROR，，R、2各地独立地为含1〜8个碳的直链或支链烷基；E为苯基、烷基取代的苯基、酰代的苯基或卤代苯基。添加聚酰磷酸酯能够提升正极极片的涂布重量，从而提高电池能量密度。

Description

正极浆料、正极极片及包括所述正极极片的二次电池 技术领域
本申请涉及锂电池技术领域，尤其涉及一种包含聚醚磷酸酯的正极极片。此外，本申请还涉及包括所述正极极片的二次电池以及包括所述二次电池的电池包、电池模块和用电装置。
背景技术
近年来，随着锂离子电池的应用范围越来越广泛，锂离子电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于锂离子电池取得了极大的发展，因此对其能量密度的提升和成本的降低提出了更高的要求。
目前，提升锂离子电池能量密度的其中一种有效方式是提高正极极片的涂布重量。然而，提高正极极片的涂布重量，会导致极片制造时存在严重的风险。由于正极浆料特性和极片特性直接影响电芯的制作，因此提高正极极片的涂布重量也会导致电芯难以制成。
因此，正极极片仍有待改进。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种包含特定聚醚磷酸酯的正极浆料以及使用所述正极浆料制备的正极极片或包括所述正极浆料的正极极片。
因此，本申请的第一方面提供了一种正极浆料，其包括正极活性物质和聚醚磷酸酯，其中，所述聚醚磷酸酯至少包括如下结构单元：
Figure PCTCN2021133144-appb-000001
Figure PCTCN2021133144-appb-000002
以及结构单元(IV)磷酸酯基团，
其中，
A为氢、卤素或卤代烷基，所述卤素可选为氟、氯或溴，所述A可选为氢或氟甲基；
B为羟基、R、OR、或ROR’，其中R、R’各地独立地为含1～8个碳的直链或支链烷基；可选地，B为甲基、乙基或乙氧基甲基；
E为苯基、烷基取代的苯基、醚代的苯基或卤代苯基，所述E可选为苯基或氟苯基。
在本申请的任意实施方案中，在向正极浆料中添加所述聚醚磷酸酯后，所得到的锂离子电池的能量密度明显提升。另外，由于正极极片的改进，可节省电芯的用量，从而降低了电芯的物料总成本。
在一些实施方式中，所述聚醚磷酸酯的数均分子量范围为10,000～80,000，可选范围为10,000～60,000，更可选范围为30,000～50,000。
分子量过小时，正极浆料稳定性较差，容易发生物理凝胶的现象，并且会使正极膜片电阻劣化，对电池性能也产生不良影响。分子量过大，则不利于聚醚磷酸酯在正极浆料中的分散。因此，所述聚醚磷酸酯的数均分子量须控制上上述范围内。
基于结构单元(I)～结构单元(IV)的总摩尔量计，结构单元(I)的摩尔占比为0-75摩尔％，结构单元(II)的摩尔占比为0-65摩尔％，结构单元(III)的摩尔占比为5-65摩尔％，结构单元(IV)的摩尔占比 为4-15摩尔％，其中结构单元(I)和结构单元(II)的摩尔占比不同时为零。
上述结构单元(I)-(IV)的摩尔占比能够确保所得到的聚醚磷酸酯与正极活性物质、集流体等之间形成足够的氢键和合适量的共价键，进而保证正极极片制备过程中的稳定性并且确保正极极片的柔韧性和各种正极物质的分散性，从而改善电池的能量密度。
在一些实施方式中，所述聚醚磷酸酯与所述正极活性物质的重量比为0.0005～0.030，可选范围为0.001～0.02，更可选范围为0.001～0.01，最可选范围为0.001～0.007。
当该比值过小时，正极极片在高涂布重量时发生开裂，当该比值过大时，会对电池性能产生不利影响。
在一些实施方式中，所述正极活性物质选自磷酸铁锂、磷酸锰铁锂、锰酸锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、镍酸锂或它们的混合物中的至少一种。
当正极活性物质为磷酸铁锂、磷酸锰铁锂、锰酸锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、镍酸锂或它们的混合物中的至少一种时，添加所述聚醚磷酸酯能够更好的实现改善极片柔韧性、提高极片最大涂布重量等效果。
在一些实施方式中，所述正极浆料的凝胶态因子G范围为0～1，可选范围为0～0.3，
其中G＝(m1-m2)/m1，G＝0～0.3时，判定浆料不凝胶，G＞0.3时，判定为凝胶；
m1为采用100目滤网将2kg初始正极浆料过滤10分钟后得到的正极浆料的质量，
m2为采用100目滤网将2kg的放置48小时的正极浆料过滤10分钟后得到的正极浆料的质量，其中，
测定m1时使用的所述正极浆料和测定m2时使用的所述正极浆料为同一批正极浆料。
正极浆料静置48h后过滤得到的正极浆料的质量与初始得到的质量越相近，G值越小，表明浆料越不容易凝胶性，浆料状态越好。本申请所述正极浆料的凝胶性能非常好。
本申请的第二方面提供一种正极极片，其包括
正极集流体；以及
位于所述正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请第一方面所述的正极浆料。如上所述，通过添加所述聚醚磷酸酯，本申请允许正极极片上最大涂布重量提高。这也表现在正极膜层的最大重量的增加。在一些实施方式中，所述正极膜层在单位面积极片上的质量的范围为13-43mg/cm 2，可选范围为22-31mg/cm 2，更可选范围为22-29mg/cm 2，所述质量为极片单个表面上的正极膜层的质量。如果正极极片上两个表面上均有正极膜层，则正极膜层在单位面积极片上的质量范围为上述范围的2倍，即，范围为26～86mg/cm 2，可选范围为44～62mg/cm 2，更可选范围为44～58mg/cm 2，所述质量为极片两个表面上的正极膜层的质量。
当单位面积极片上的正极膜层的重量过小时，极片均一性差；当单位面积极片上的正极膜层的重量过大时，极片涂布过程严重开裂，无法继续生产。本申请将单位面积极片上的正极膜层的重量限于上述范围内，确保在该范围内能够实现最好的效果。
本申请所述的正极极片具有非常好的柔韧性，并且涂布重量得到了显著改善。将所述正极极片应用于二次电池中，例如，在制备时直接加入到正极浆料中，可显著提高电池的能量密度。
在一些实施方式中，所述正极膜层包括两个亚层，所述亚层平行于所述正极集流体且互相叠置，其中与所述正极集流体最接近的亚层中的聚醚磷酸酯的重量含量相对于与所述正极集流体距离最远的亚层中的聚醚磷酸酯的重量含量之比的范围为0～60，可选范围为0.1～30。
当涂布重量在23mg/cm 2以上时，与单次厚涂布相比，两次涂布可降低柔性添加剂的物料成本，同时本申请所述的聚醚磷酸酯可以更好地发挥作用而不影响电性能。
在一些实施方式中，通过本申请所述卷针测量所述正极极片的柔韧性时，
在卷针直径R≤3.0mm时，所述正极极片不产生裂纹，或者，
在卷针直径R＝3.0mm时，所述正极极片产生裂纹，但在卷针直径R＝4.0mm时无裂纹。
添加了本申请所述的聚醚磷酸酯后，可降低冷压压力，从而减少裂纹，减少断带风险，进而改善了极片的柔韧性。
在一些实施方式中，所述正极极片的浸润率提升率I范围为2～20％，可选范围为6～15％，
其中I＝(I2-I1)/I1×100％，
I2为所述正极极片在电解液中的浸润率，
I1为不包括所述聚醚磷酸酯的正极极片在电解液中的浸润率，
其中测定I1时使用的正极极片和测定I2时使用的所述正极极片相同，不同之处仅在于测定I1时使用的正极极片中不包括所述聚醚磷酸酯，而测定I2时使用的所述正极极片中含有所述聚醚磷酸酯。
极片的浸润性好，可以实现对电解液良好的浸润和保液性，从而实现电芯极片的有效浸润，避免极片浸润不充分，提升电芯注液效率及循环过程中极片的浸润性，从而有效提高电池产品性能。本申请所述正极极片在电解液中的浸润性能非常好。
本申请的第三方面提供一种二次电池，其中，包括本申请第一方面所述的负极极片。
本申请的第四方面提供一种电池模块，其包括本申请第二方面所述的二次电池。
本申请的第五方面提供一种电池包，其包括本申请第三方面所述的电池模块。
本申请的第六方面提供一种用电装置，其包括本申请第三方面所述的二次电池、本申请第四方面所述的电池模块或本申请第五方面所述的电池包中的至少一种。
附图说明
图1为本申请正极极片中聚醚磷酸酯与正极极片中其他物质之间相互作用的原理示意图，其中聚醚磷酸酯为本申请所述的聚醚磷酸酯。
图2为现有技术中出现的正极极片在涂布过程中由于毛细管张力引起的涂布开裂的过程的示意图，其中活性物质为正极活性物质，且作用力为涂布过程中的作用力，其中不使用本申请所述的聚醚磷酸酯。
图3为本申请所述的正极极片在涂布过程中无开裂的示意图，其中活性物质为正极活性物质，作用力为涂布过程中的作用力，并且其中使用了本申请所述的聚醚磷酸酯。
图4为在使用本申请的聚醚磷酸酯后正极极片中单位面积最大涂布重量增加的示意图，其中正极材料表示正极活性物质材料，SP表示正极极片中使用的导电剂，PVDF表示正极极片中使用的粘结剂；其中X表示不包含聚醚磷酸酯的正极浆料的最大涂布厚度，Y表示在同样条件下包含聚醚磷酸酯的正极浆料的最大涂布厚度，很明显，Y大于X。
图5为本申请正极极片的柔韧性测试中使用的卷针的示意图。
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负极极片及其制造方法、正极极片、二次电池、电池模块、电池包和电学装置的实施方式。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2-6。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，可选是顺序进行的。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)。
发明构思
对锂离子电池而言，提升能量密度是趋势所向，而提升能量密度的其中一种方式是提高正极极片的涂布重量。然而，本申请发明人发现，如图2所示，在常规的正极浆料的涂布过程中，在溶剂蒸发过程中或溶剂蒸发之后，由于毛细管张力的作用，正极极片会开裂，并且所述开裂 会进一步传播，造成大面积开裂。此外，在此过程中还伴有极片边缘卷曲的现象。另外，由于正极极片硬脆，在冷压过程中会断带，卷绕过程中内圈会发生严重断裂。基于此，本申请发明人设计合成了一种柔性高分子材料聚醚磷酸酯，通过添加该柔性材料来提高涂布重量，改善涂布质量，并消除冷压和卷绕过程中带来的风险问题，同时降低了制造电池使用的物料的总成本。
因此，本申请的第一方面提供了一种正极浆料，其包括正极活性物质和聚醚磷酸酯，所述聚醚磷酸酯至少包括如下结构单元：
Figure PCTCN2021133144-appb-000003
Figure PCTCN2021133144-appb-000004
以及结构单元(IV)磷酸酯基团，
其中，
A为氢、卤素或卤代烷基，所述卤素可选为氟、氯或溴，所述A可选为氢或氟甲基；
B为羟基、R、OR、或ROR’，其中R、R’各地独立地为含1～8个碳的直链或支链烷基；可选地，B为甲基、乙基或乙氧基甲基；
E为苯基、烷基取代的苯基、醚代的苯基或卤代苯基，所述E可选为苯基或氟苯基。
在本申请所述的聚醚磷酸酯中，结构单元(IV)作为端基存在。
可选地，在一些实施方式中，所述聚醚磷酸酯由以下组分聚合而成：
(a)未被取代或被卤素或卤代C 1-8烷基取代的环氧乙烷；
(b)被羟基、羟烷基、R、OR、或ROR’取代的环氧乙烷，其中R、R’各自独立地为C 1-8烷基，其中羟烷基中的烷基为C 1-8烷基；
(c)被卤代苯基、卤代烷基苯基或苯基取代的环氧乙烷；
(d)磷化剂，其为五氧化二磷；
其中，基于组分(a)-(d)的总的摩尔量计，组分(a)的摩尔占比为0-75摩尔％；组分(b)的摩尔占比为0-65摩尔％；组分(c)的摩尔占比为5-65摩尔％；组分(d)的摩尔占比为4-15摩尔％，
其中组分(a)和(b)不同时为零。
在一些实施方式中，可选地，组分(a)选自环氧乙烷、环氧氟丙烷、环氧氯丙烷、环氧溴丙烷。
在一些实施方式中，可选地，组分(b)选自环氧丙烷、乙基缩水甘油基醚、异丙基缩水甘油醚、丁基缩水甘油醚、异丙基缩水甘油醚、环氧丁烷、1,2-环氧丁烷、1,2-环氧戊烷、1,2-环氧庚烷、1,2-环氧辛烷、1,2-环氧癸烷、1,2-环氧-3-甲基丁烷、缩水甘油。
在一些实施方式中，可选地，组分(c)选自氧化苯乙烯、苯基。
本申请中，C 1-8烷基为含1-8个碳的直链或支链烷基，所述含1-8个碳的直链或支链烷基可选自，例如，甲基、乙基、丙基、丁基、戊基、己基、庚基、辛基、异丙基、异丁基、叔丁基、异戊基、叔戊基、新戊基、2-甲基戊基、3-甲基戊基、2,2-二甲基丁基、2,3-二甲基丁基、2-甲基己基、3-甲基己基、2,2-二甲基戊基、3,3-二甲基戊基、2,3-二甲基戊基、2,4-二甲基戊基、3-乙基戊基、2,2,3-三甲基丁基、2-甲基庚基、3-甲基庚基、4-甲基庚基、2,2-二甲基己烷、3,3-二甲基己烷、2,3-二甲基己烷、2,4-二甲基己烷、2,5-二甲基己烷、3,4-二甲基己烷、3-乙基己烷、2,2,3-三甲基戊烷、2,2,4-三甲基戊烷、2,3,3-三甲基戊烷、2,3,4-三甲基戊烷、2-甲基-3-乙基戊烷、3-甲基-3-乙基戊烷、2,2,3,3-四甲基丁烷。
本申请中，C 1-8烯基为含1-8个碳的直链或支链烯基，其可包括，但不限于，乙烯基、丙烯基、烯丙基、1-甲基丙-2-烯-1-基、2-甲基丙-2-烯-1-基、丁-2-烯-1-基、丁-3-烯-1-基、1-甲基丁-3-烯-1-基和1-甲基丁-2-烯-1-基等。
本申请中，烷基取代基可为含1-8个碳的直链或支链烷基，其可选地选自甲基、乙基、丙基、异丙基、正丁基、异丁基、叔丁基。可选地，所述烷基取代为单取代或二取代。在一些实施方式中，烷基取代的苯基可以选自，例如，3,4-二甲基苯基、2-甲基苯基、3,5-二甲基苯基、4-(2-甲基丙基)苯基。
本申请中，卤代烷基中的烷基可选为含1-8个碳的直链或支链烷基，例如，所述卤代烷基中的烷基可选地选自甲基、乙基、丙基、丁基、戊基、己基、庚基、辛基、异丙基、异丁基、叔丁基、异戊基、叔戊基、新戊基、2-甲基戊基、3-甲基戊基、2,2-二甲基丁基、2,3-二甲基丁基、2-甲基己基、3-甲基己基、2,2-二甲基戊基、3,3-二甲基戊基、2,3-二甲基戊基、2,4-二甲基戊基、3-乙基戊基、2,2,3-三甲基丁基、2-甲基庚基、3-甲基庚基、4-甲基庚基、2,2-二甲基己烷、3,3-二甲基己烷、2,3-二甲基己烷、2,4-二甲基己烷、2,5-二甲基己烷、3,4-二甲基己烷、3-乙基己烷、2,2,3-三甲基戊烷、2,2,4-三甲基戊烷、2,3,3-三甲基戊烷、2,3,4-三甲基戊烷、2-甲基-3-乙基戊烷、3-甲基-3-乙基戊烷、2,2,3,3-四甲基丁烷。所述卤代烷基中的卤素可选自氟、氯、溴、碘。
本申请中，醚基取代基可为含1-8个碳的直链或支链烷氧基，可选地选自甲氧基、乙氧基、丙氧基或丁氧基。在一些实施方式中，醚代的苯基可选自，例如，4-甲氧基苯基、3-甲氧基苯基等。
本申请中，卤代烷基苯基指被卤代烷基取代的苯基，其中卤代烷基指被卤素取代的烷基，其中烷基为C 1-8烷基。
本申请中，卤代苯基代表被卤素取代的苯基。本申请中，卤素可选自氟、氯、溴、碘。在一些实施方式中，卤代的苯基可选自，例如，4-氟苯基、2-氟苯基、2,6-二氟苯基、4-(三氟甲基)苯基、4-氯苯基、3-氯苯基、4-溴苯基、3-溴苯基或2-溴苯基。
本申请所述的聚醚磷酸酯的结构式(1)中结构单元(I)(或组分(a)形成的结构单元)可以提高聚合物与正极颗粒表面、导电碳、铝箔之间形成氢键的能力；结构单元(II)(或组分(b)形成的结构单元)可以延长分子的支链，保证所述聚醚磷酸酯与正极颗粒表面、导电碳、 铝箔表面形成共价键，保证正极颗粒在涂布过程中不迁移；结构单元(III)(或组分(c)形成的结构单元)能够提高所述聚醚磷酸酯的刚性，使其具备一定的强度和硬度，从而提高聚醚磷酸酯的抗氧化性和耐电解液性，同时苯环与正极颗粒表面形成相互作用，保证聚醚磷酸酯的分散性。磷酸酯端基起锚定作用，可作为润湿分散剂将正极活性组分颗粒均匀稳定分散于NMP介质中。
如图1所示，本申请的聚醚磷酸酯为长长的柔性链，其既可通过结构单元(I)(或组分(a)形成的结构单元)与正极活性物质、正极集流体之间形成氢键，也可通过结构单元(II)(或组分(b)形成的结构单元)与正极活性物质、正极集流体之间形成共价键，此外还可通过结构单元(III)(或组分(c)形成的结构单元)中的苯环与正极活性物质颗粒表面相互作用。另外，本申请的聚醚磷酸酯之间也可以形成共价键。因此，通过向正极浆料中加入柔性添加剂，即，本申请所述的聚醚磷酸酯，能够提高正极浆料的稳定性，提高正极极片的柔韧性，并且保证正极极片中各物质的分散性，从而能够提高正极极片的涂布重量。如图3所示，在添加了所述聚醚磷酸酯后，本申请的正极浆料在整个涂布过程中都没有开裂。如图4所示，在添加了本申请的聚醚磷酸酯后，正极极片中的最大涂布厚度(重量)明显提高。
本申请所述的聚醚磷酸酯可根据本领域常规技术手段获得，也可使用以下步骤制备：
步骤1：使环氧烷烃单体在碱性条件下生成聚醚，其中，可选地，使用的溶剂为二甲基亚砜、丙酮、乙醚中的一种或多种；可选地，在制备中可能添加的碱性物质为，例如，NaOH、KOH、二环己基碳二亚胺；可选地，该反应的反应温度范围为80～160℃，反应时间范围为3-7h；可选地，反应过程中搅拌速度范围为1000-2000转/分钟；可选地，反应结束后，进行减压蒸馏纯化步骤。
步骤2：使步骤(1)中的聚醚与磷化剂反应生成聚醚磷酸酯，其中，可选地，反应在反应釜中进行；可选地，该反应的范围温度范围为60～130℃；可选地，反应时间范围为2～15h；可选地，在反应过程中进 行搅拌，搅拌时间范围可选为1～10h，搅拌速度范围可选为1000-2000r/min；可选地，反应结束后，进行减压蒸馏纯化步骤。
在一些实施方案中，本申请所述的正极浆料在20～60℃下的pH范围为约6～9。pH值根据本领域常规手段测试。
在本申请的任意实施方案中，在向正极浆料中添加所述聚醚磷酸酯后，所得到的锂离子电池的能量密度明显提升。另外，由于正极极片的改进，可节省电芯的用量，从而降低了电芯的物料总成本。
在一些实施方式中，所述聚醚磷酸酯的数均分子量范围为10,000～80,000，可选范围为10,000～60,000，更可选范围为30,000～50,000。
分子量大小对正极极片的加工性能有影响。在分子量较小的情况下，正极极片的柔韧性改善不明显，依然会有在涂布中开裂的现象，并且可能出现冷压断带和卷绕断裂的问题。分子量过小时，正极浆料稳定性较差，容易发生物理凝胶的现象，并且会使正极膜片电阻劣化，对电池性能也产生不良影响。分子量过大，则不利于聚醚磷酸酯在正极浆料中的分散。因此，所述聚醚磷酸酯的数均分子量须控制上上述范围内。
在一些实施方式中，在本申请所述聚醚磷酸酯中，基于结构单元(I)～结构单元(IV)的总摩尔量计，结构单元(I)的摩尔占比为0-75摩尔％，结构单元(II)的摩尔占比为0-65摩尔％，结构单元(III)的摩尔占比为5-65摩尔％，结构单元(IV)的摩尔占比为4-15摩尔％，其中结构单元(I)和结构单元(II)的摩尔占比不同时为零。
可选地，基于结构单元(I)～结构单元(IV)的总摩尔量计，结构单元(I)的摩尔占比(或基于组分(a)～(d)的总摩尔量计，组分(a)的摩尔占比)可为约0摩尔％、约5摩尔％、约10摩尔％、约14摩尔％、约15摩尔％、约17摩尔％、约20摩尔％、约25摩尔％、约26摩尔％、约27摩尔％、约28摩尔％、约29摩尔％、约30摩尔％、约31摩尔％、约32摩尔％、约33摩尔％、约35摩尔％、约40摩尔％、约42摩尔％、约45摩尔％、约50摩尔％、约55摩尔％、约60摩尔％、约62摩尔％、约65摩尔％、约68摩尔％、约70摩尔％、约72摩尔％或约75摩尔％。或者，结构单元(I)的摩尔占比在上述任意值组成的任意范围内。
可选地，基于结构单元(I)～结构单元(IV)的总摩尔量计，结构单元(II)的摩尔占比(或基于组分(a)～(d)的总摩尔量计，组分(b)的摩尔占比)可为约0摩尔％、约5摩尔％、约10摩尔％、约14摩尔％、约15摩尔％、约17摩尔％、约20摩尔％、约22摩尔％、约25摩尔％、约30摩尔％、约31摩尔％、约35摩尔％、约40摩尔％、约42摩尔％、约43摩尔％、约45摩尔％、约50摩尔％、约52摩尔％、约53摩尔％、约54摩尔％、约55摩尔％、约56摩尔％、约58摩尔％、约60摩尔％、约63摩尔％、约65摩尔％。或者，结构单元(II)的摩尔占比在上述任意值组成的任意范围内。
可选地，基于结构单元(I)～结构单元(IV)的总摩尔量计，结构单元(III)的摩尔占比(或基于组分(a)～(d)的总摩尔量计，组分(c)的摩尔占比)为约5摩尔％、约6摩尔％、约7摩尔％、约9摩尔％、约10摩尔％、约11摩尔％、约15摩尔％、约20摩尔％、约23摩尔％、约24摩尔％、约25摩尔％、约26摩尔％、约30摩尔％、约31摩尔％、约33摩尔％、约35摩尔％、约40摩尔％、约45摩尔％、约50摩尔％、约55摩尔％、约59摩尔％、约60摩尔％、约61摩尔％或约65摩尔％。或者，结构单元(III)的摩尔占比在上述任意值组成的任意范围内。
可选地，基于结构单元(I)～结构单元(IV)的总摩尔量计，结构单元(IV)的摩尔占比(或基于组分(a)～(d)的总摩尔量计，组分(d)的摩尔占比)为约4摩尔％、约5摩尔％、约6摩尔％、约7摩尔％、约8摩尔％、约9摩尔％、约10摩尔％、约11摩尔％、约12摩尔％、约13摩尔％、约14摩尔％或约15摩尔％。或者，结构单元(IV)的摩尔占比在上述任意值组成的任意范围内。
本申请中，“约”某个数值表示一个范围，即该数值的±3％的范围。
上述结构单元(I)-(IV)(或组分(a)-(d))的摩尔占比能够确保所得到的聚醚磷酸酯与正极活性物质、集流体等之间形成足够的氢键和合适量的共价键，进而保证正极极片制备过程中的稳定性并且确保正极极片的柔韧性和各种正极物质的分散性，从而改善电池的能量密度。
在一些实施方式中，所述聚醚磷酸酯与所述正极活性物质的重量比为0.0005～0.030，可选范围为0.001～0.02，更可选范围为0.001～0.01，最可选范围为0.001～0.007。
所述聚醚磷酸酯与所述正极活性物质的重量比为0.0005～0.030。当该比值过小时，正极极片在高涂布重量时发生开裂，当该比值过大时，会对电池性能产生不利影响。
在一些实施方式中，所述正极活性物质选自磷酸铁锂、磷酸锰铁锂、锰酸锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、镍酸锂或它们的混合物中的至少一种。
理论上，对于二次电池的正极，本申请可采用本领域公知的用于电池的任何正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
然而，本申请发明人发现，当正极活性物质为磷酸铁锂、磷酸锰铁锂、锰酸锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、镍酸锂或它们的混合 物中的至少一种时，添加所述聚醚磷酸酯能够更好的实现改善极片柔韧性、提高极片最大涂布重量等效果。
在一些实施方式中，所述正极浆料的凝胶态因子G范围为0～1，可选范围为0～0.3，
其中G＝(m1-m2)/m1，G＝0～0.3时，判定浆料不凝胶，G＞0.3时，判定为凝胶；
m1为采用100目滤网将2kg初始正极浆料过滤10分钟后得到的正极浆料的质量，
m2为采用100目滤网将2kg的放置48小时的正极浆料过滤10分钟后得到的正极浆料的质量，其中，
测定m1时使用的所述正极浆料和测定m2时使用的所述正极浆料为同一批正极浆料。
正极浆料静置48h后过滤得到的正极浆料的质量与初始得到的质量越相近，G值越小，表明浆料越不容易凝胶性，浆料状态越好。本申请所述正极浆料的凝胶性能非常好。
本申请的第二方面提供一种正极极片，其包括
正极集流体；以及
位于所述正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请第一方面所述的正极浆料。如上所述，通过添加所述聚醚磷酸酯，本申请允许正极极片上最大涂布重量提高。这也表现在正极膜层的最大重量的增加。在一些实施方式中，所述正极膜层在单位面积极片上的质量的范围为13-43mg/cm 2，可选范围为22-31mg/cm 2，更可选范围为22-29mg/cm 2，所述质量为极片单个表面上的正极膜层的质量。如果正极极片上两个表面上均有正极膜层，则正极膜层在单位面积极片上的质量范围为上述范围的2倍，即，范围为26～86mg/cm 2，可选范围为44～62mg/cm 2，更可选范围为44～58mg/cm 2，所述质量为极片两个表面上的正极膜层的质量。
在一些实施方式中，在添加本申请所述的聚醚磷酸酯之后，正极极片上单位面积的涂布重量最大可达41mg/cm 2，可选地，正极极片上单位面积的涂布重量最大可在23-41mg/cm 2范围内。
当单位面积极片上的正极膜层的重量过小时，极片均一性差；当单位面积极片上的正极膜层的重量过大时，极片涂布过程严重开裂，无法继续生产。本申请将单位面积极片上的正极膜层的重量限于上述范围内，确保在该范围内能够实现最好的效果。
所述正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在所述正极极片中，正极活性物质在正极膜层中的质量含量为90-97％，基于正极膜层计。该含量可以使用EDS进行测量。该质量含量过小时，所制备的电池能量密度低，无法满足电池容量需求；该质量含量过大时，粘结剂和导电剂不足，导致电池性能差。
在所述正极极片中，在正极膜层中的粘结剂质量含量为2～5％，基于正极膜层的总质量计。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。现有的常规正极极片中使用特定结晶度或类似结晶度的粘结剂，经涂布、烘干成膜后较脆，在应力作用下，极片容易开裂，而本申请正极极片中使用同样具有这种结晶度的粘结剂，极片不开裂。
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，例如正极活性物质、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
本申请所述的正极极片具有非常好的柔韧性，并且涂布重量得到了显著提升。将所述正极极片应用于二次电池中，例如，在制备时直接加入到正极浆料中，可显著提高电池的能量密度。
在一些实施方式中，所述正极膜层包括两个亚层，所述亚层平行于所述正极集流体且互相叠置，其中与所述正极集流体最接近的亚层(即，离集流体近的亚层)中的聚醚磷酸酯的重量含量相对于与所述正极集流体距离最远的亚层(即，离集流体远的亚层)中的聚醚磷酸酯的重量含量之比的范围为0～60，可选范围为0.1～30。
在一些实施方式中，与所述正极集流体最接近的亚层中的聚醚磷酸酯的重量含量相对于与所述正极集流体距离最远的亚层中的聚醚磷酸酯的重量含量之比可为约0.1、约0.2、约0.3、约0.4、约0.5、约0.6、约0.7、约0.8、约0.9、约1、约2、约3、约4、约5、约6、约7、约8、约9、约10、约11、约12、约13、约14、约15、约16、约17、约18、约19、约20、约21、约22、约23、约24、约25、约26、约27、约28、约29、约30、约31、约32、约33、约34、约35、约36、约37、约38、约39、约40、约41、约42、约43、约44、约45、约46、约47、约48、约49、约50、约51、约52、约53、约54、约55、约56、约57、约58、约59或约60。或者，与所述正极集流体最接近的亚层中的聚醚磷酸酯的重量含量相对于与所述正极集流体距离最远的亚层中的聚醚磷酸酯的重量含量之比在上述任意值组成的任意范围内。
在一些可选实施方式中，离集流体近的亚层中，所述聚醚磷酸酯与所述正极活性物质的重量比为0～0.043；在离集流体远的亚层中，所述聚醚磷酸酯与所述正极活性物质的重量比为0.0006～0.004。
当涂布重量在23mg/cm 2以上时，与单次厚涂布相比，多次涂布可降低柔性添加剂的物料成本，同时本申请所述的聚醚磷酸酯可以更好地发挥作用而不影响电性能。
可选地，在制备具有两个亚层的正极膜层时，首先制备两种包含不同量的聚醚磷酸酯的正极浆料，然后将一种浆料涂覆在集流体上，烘干，再涂覆另一层浆料，再烘干。
在一些实施方式中，通过卷针测量所述正极极片的柔韧性时，
在卷针直径R≤3.0mm时，所述正极极片不产生裂纹，或者，
在卷针直径R＝3.0mm时，所述正极极片产生裂纹，但在卷针直径R＝4.0mm时无裂纹。
在任意实施方式中，在根据本申请所述的正极极片中，通过卷针测量所述正极极片的柔韧性时，制备长宽50mm×长度为100mm的极片样品，在特制的卷针上进行卷绕，用目测和显微镜结合的方式，观察极片裂纹情况。根据以下方法判断柔韧性等级：
卷针的直径为R，
R≤3.0mm时极片不产生裂纹，为柔韧性一级；
R＝3.0mm有裂纹，R＝4.0mm无裂纹，为柔韧性二级
R＝4.0mm有裂纹，R＝5.0mm有裂纹，为柔韧性三级；
R＝5.0mm无裂纹，R＝6.0mm有裂纹，为柔韧性四级；
R＝6.0mm无裂纹，R＝7.0mm有裂纹，为柔韧性五级。
卷针的制备方法如下：
将常规直径分别为3.0mm、4.0mm、5.0mm、6.0mm、7.0mm的304不锈钢棒截取60mm，焊接于150mm×300mm的钢板上进行固定即得所述卷针。
使用的卷针直径越小而极片又不开裂，表明极片的柔韧性越好，反之，使用的卷针直径越大而极片又裂纹，表明极片的柔韧性越差。
在冷压过程中，已形成的氢键被破坏，柔性主链伸展。但添加了本申请所述的聚醚磷酸酯后，可降低冷压压力，从而减少裂纹，减少断带风险。
在一些实施方式中，所述正极极片的浸润率提升率I范围为2～20％，可选范围为6～15％，
其中I＝(I2-I1)/I1×100％，
I2为所述正极极片在电解液中的浸润率，
I1为不包括所述聚醚磷酸酯的正极极片在电解液中的浸润率，
其中测定I1时使用的正极极片和测定I2时使用的所述正极极片相同，不同之处仅在于测定I1时使用的正极极片中不包括所述聚醚磷酸酯，而测定I2时使用的所述正极极片中含有所述聚醚磷酸酯。
极片的浸润性好，可以实现对电解液良好的浸润和保液性，从而实现电芯极片的有效浸润，避免极片浸润不充分，提升电芯注液效率及循环过程中极片的浸润性，从而有效提高电池产品性能。本申请所述正极极片在电解液中的浸润性能非常好。
本申请的第三方面提供一种二次电池，其中，包括根据本申请第二方面所述的正极极片，或者，使用根据本申请第一方面所述的正极浆料制备。本申请所述的二次电池的能量密度得到了明显提升。此外，在制备所述电池时，物料总成本降低。
下面对本申请的二次电池、电池模块、电池包和用电装置进行说明。
二次电池
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极极片]
采用本申请第二方面所述的正极极片或使用根据本申请第一方面所述的正极浆料制备。
[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、磷基材料、锡基材料和钛酸锂等。所述磷基材料可选自单质磷、磷氧化合物、磷碳复合物、磷氮复合物以及磷合金中的至少一种。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，电解质可以选自固态电解质及液态电解质(即电解液)中的至少一种。
在一些实施方式中，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(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸锂(LiTFOP)中的一种或几种。
在一些实施方式中，溶剂可选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
在一些实施方式中，电解液中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，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。隔离膜设置在正极极片和负极极片之间起到隔离的作用。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。
[外包装]
在一些实施方式中，二次电池可以包括外包装，用于封装正极极片、负极极片和电解质。作为一个示例，正极极片、负极极片和隔离膜可经叠片或卷绕形成叠片结构电芯或卷绕结构电芯，电芯封装在外包装内；电解质可采用电解液，电解液浸润于电芯中。二次电池中电芯的数量可以为一个或几个，可以根据需求来调节。
在一个实施方式中，本申请提供一种电极组件。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。所述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软包，例如袋式软包。软包的材质可以是塑料，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)等中的一种或几种。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。
二次电池的制备方法
在一个实施方式中，本申请提供一种二次电池的制备方法，其中，使用本申请所述的负极极片或根据本申请所述的方法制备的负极极片。
二次电池的制备还可以包括将本申请的负极极片、正极极片和电解质组装形成二次电池的步骤。在一些实施方式中，可将正极极片、隔离膜、负极极片按顺序卷绕或叠片，使隔离膜处于正极极片与负极极片之间起到隔离的作用，得到电芯。将电芯置于外包装中，注入电解液并封口，得到二次电池。
在一些实施方式中，二次电池的制备还可以包括制备正极极片的步骤。作为示例，可以将正极活性物质、导电剂和粘结剂分散于溶剂(例如N-甲基吡咯烷酮，简称NMP)中，形成均匀的正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，得到正极极片。
在一些实施方式中，二次电池的制备包括根据本申请所述的方法制备负极极片的步骤。
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。
在一些实施方式中，本申请提供一种用电装置、电池模块或电池包，其中，所述用电装置、电池模块或电池包包括如本申请所述的二次电池或根据本申请所述的方法制备的二次电池。
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。
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。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。作为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。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。
因此，本申请提供一种电池模块，其包括本申请所述的二次电池。
此外，本申请还提供一种电池包，其包括上述电池模块。
本申请进一步提供一种用电装置，其包括本申请所述的二次电池、上述电池模块或上述电池包中的至少一种。
实施例
下面通过实施例来详细说明本申请，该说明是非限制性的。
1.聚醚磷酸酯的制备
步骤1：使前驱体1、前驱体2、前驱体3(具体种类和用量参见表1)在碱性条件下生成聚醚，当聚醚的数均分子量达到2w(即20000)时，停止反应；
步骤2：使步骤(1)中制备的聚醚与磷化剂(五氧化二磷)(具体用量参见表1)反应生成聚醚磷酸酯，反应完毕后，经过滤、透析，截取数均分子量为2w-3w(即20000-30000)的聚醚磷酸酯。
2.正极浆料的制备
将正极活性物质(磷酸铁锂)、导电剂(导电炭黑Super P)、粘接剂PVDF(具体用量参见表2)混合30min。然后将所得到的混合物加入NMP中，并搅拌180min以使其均匀分散。最后加入步骤1制备的聚醚磷酸酯，再充分搅拌60min，使其形成均匀的正极浆料。
3.正极极片的制备
将该正极浆料涂覆于正极集流体铝箔的表面上，极片经干燥、冷压后，得到正极极片。经一系列正极极片性能测试(主要是(1)测试极片涂布时是否开裂，(2)冷压后是否断裂，(3)进行本文所述的正极极片的柔韧性测试方法，柔韧性二级以下且涂布时不开裂、冷压后不断裂的最大涂布重量即为单位面积最大涂布重量)，单位面积最大涂布重量为41mg/cm 2。
4.负极极片的制备
将负极活性物质(石墨)、导电剂(Super P)、粘接剂(SBR)、增稠剂(CMC)按96.2:0.8:1.8:1.2的质量比在适量的去离子水中充分搅拌混合，使其形成均匀的负极浆料。将此负极浆料涂覆于负极集流体铜箔的两个表面上，经干燥、冷压后，得到负极极片。
5.电解液的制备
将碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)体积比1:1:1混合，然后将LiPF 6均匀溶解在上述溶液中得到电解液，其中LiPF 6的浓度为1mol/L。
6.隔离膜
采用聚乙烯(PE)薄膜。
7.二次电池的制备
将上述正极极片、隔离膜、负极极片按顺序叠好，经卷绕后得到电极组件，将电极组件装入外包装中，加入上述电解液，经封装、静置、化成、老化等工序后，得到实施例1的二次电池。所述外包装选择长×宽×高为148mm×28.5mm×97.5mm的硬壳壳体。
实施例2～19和对比例1
类似于实施例1进行，不同之处在于使用如表1、表2所示的原料和用量以及在制备中各自截取如表5-6中所示的聚醚磷酸酯的数均分子量，其中对比例1中不使用聚醚磷酸酯。
实施例21
步骤1、4-7的制备过程参照实施例1，聚醚磷酸酯数均分子量的截取范围如表8所示，步骤2-3的制备过程更改如下：
步骤2：正极浆料的制备
将3124.9g的正极活性物质(磷酸铁锂)、32.5g的导电剂(Super P)、81.25g的粘结剂PVDF混合30min。然后将所得到的混合物加入1750g的NMP溶剂中，并搅拌180min以使其均匀分散。最后加入步骤1中制备的11.38g的聚醚磷酸酯，再充分搅拌60min，使其形成均匀的正极浆料1。
将3134.6g的正极活性物质(磷酸铁锂)、32.5g的导电剂(Super P)、81.25g的粘结剂PVDF混合30min。然后将所得到的混合物加入1750g的NMP溶剂中，并搅拌180min以使其均匀分散。最后加入1.63g的步骤1中制备的聚醚磷酸酯，再充分搅拌60min，使其形成均匀的正极浆料2。
步骤3：正极极片的制备
将步骤2中的正极浆料1涂覆于正极集流体铝箔的表面上，经干燥后，再将正极浆料2涂覆于干燥后的浆料1的表面上，正极浆料1与正极浆料2的涂布厚度保持一致。经一系列正极极片性能测试(主要是测试极片涂布时是否开裂，冷压后是否断裂，参见本文所述的正极极片的柔韧性测试方法，柔韧性二级以下且涂布时不开裂、冷压后不断裂的最大涂布重量即为单位面积最大涂布重量)，总的单位面积涂布重量为41mg/cm 2。
实施例20
与实施例21的差别在于正极浆料1中不含聚醚磷酸酯，其他制备过程与实施例21类似，具体方法参数参见表1、表3，截取的数均分子量范围如表7所示。
实施例22～26
制备过程与实施例21类似，不同之处在于使用如表1、表3所示的原料和用量以及截取如表8所示的数均分子量。
本申请中，所有实施例和对比例中的正极极片中的均将正极浆料涂覆于正极集流体的两个表面上，即，双面涂布。
表1：聚醚磷酸酯的制备中使用的原料及用量
Figure PCTCN2021133144-appb-000005
实施例13～26中使用的前驱体1-3和磷化剂均与实施例1相同。
表2：正极浆料的制备中使用的物质及用量
制备例 正极活性材料 所用克数 聚醚磷酸酯所用克数
实施例1 磷酸铁锂 3123.25 13.00
实施例13 磷酸铁锂 3134.63 1.63
实施例14 磷酸铁锂 3038.75 97.50
实施例15 磷酸铁锂 3133.00 3.25
实施例16 磷酸铁锂 3071.25 65.00
实施例17 磷酸铁锂 3113.50 22.75
实施例18 磷酸铁锂 3135.60 0.65
实施例19 磷酸铁锂 2973.75 162.50
表2中，实施例1和13～19中，均使用了1750g的溶剂NMP，32.5g的导电碳super P，81.25g的粘结剂PVDF。实施例2-12中用于制备正极浆料的各物质用量均与实施例1相同。
表3：包括具有双层正极膜层的正极浆料的制备中每个亚层使用的物质及用量
Figure PCTCN2021133144-appb-000006
IV.本申请正极浆料和正极极片的性能评价
浆料参数的测试：
1.正极浆料的凝胶态因子
通过以下方法评价正极浆料的凝胶态：
所述正极浆料的凝胶态因子表示为G，G＝|(m2-m1)/m1|，
其中
m1为采用200目滤网将2kg初始正极浆料过滤10分钟后得到的正极浆料的质量，
m2为采用200目滤网将2kg的放置48小时的正极浆料过滤10分钟后得到的正极浆料的质量，其中，
测定m1时使用的所述正极浆料和测定m2时使用的所述正极浆料为同一批正极浆料。
G在0～0.3范围内判定不凝胶；G＞0.3判定为凝胶。
正极极片参数的测试
1.正极极片的柔韧性测试
通过卷针评价正极极片的柔韧性，测试方法如下：
制备长宽50mm×长度为100mm的极片样品，在特制的卷针上进行卷绕，用目测和显微镜结合的方式，观察极片裂纹情况。
特制的卷针：
将常规直径分别为2.0mm、3.0mm、4.0mm、5.0mm、6.0mm、7.0mm的304不锈钢棒截取60mm，焊接于150mm×300mm的钢板上进行固定即可，如图5所示。
根据以下方法判断柔韧性等级：
卷针的直径为R，
R≤3.0mm时极片不产生裂纹，为柔韧性一级；
R＝3.0mm有裂纹，R＝4.0mm无裂纹，为柔韧性二级
R＝4.0mm有裂纹，R＝5.0mm有裂纹，为柔韧性三级；
R＝5.0mm无裂纹，R＝6.0mm有裂纹，为柔韧性四级；
R＝6.0mm无裂纹，R＝7.0mm有裂纹，为柔韧性五级。
2.正极极片的浸润率提升率
所述正极极片的浸润率提升率表示为I，I＝(I2-I1)/I1×100％，
其中
I2为所述正极极片在电解液中的浸润率，
I1为不包括所述聚醚磷酸酯的正极极片在电解液中的浸润率，
其中测定I1时使用的正极极片和测定I2时使用的所述正极极片相同，不同之处仅在于测定I1时使用的正极极片中不包括所述聚醚磷酸酯，而测定I2时使用的所述正极极片中含有所述聚醚磷酸酯。
I1、I2测定过程如下：
采用毛细管法测试极片吸液速率。准备尺寸≥50mm*50mm的极片，表面平整无褶皱，无脱膜掉粉；挑选内径d＝100um的毛细管，用砂纸打磨至端口整齐，毛细管吸取电解液h＝5mm，控制电解液高度为5mm，将毛细管至于显微镜下，是其与极片接触，毛细管液面下降的同时用秒表记录时间，当液面下降完毕后，读取洗液时间，记录数据t，电解液浸润率等于
π×(d/2)^2×h×ρ/t，
其中π为3.14，ρ为电解液密度。
3.单位面积涂布重量测量
准备空白铝箔和涂布过程中已经烘干的正极极片(此正极极片正极集流体两面均有涂层)，分别冲切面积为1540.25mm 2的小圆片15个，用极片小圆片的平均质量减去空铝箔小圆片的平均质量再除以2，即可得单位面积的涂布重量。所述“单面”是指仅在集流体的一个表面进行涂布，而与本申请所述的“亚层”的层数不是同一概念。表格中的单位面积最大涂布重量是指单面重量。
本申请表格实施例中的涂布重量的数据均是指单面单位面积最大涂布重量的数据，极片性能和电池性能均在最大涂布重量下测量。
单位面积最大涂布重量是指在(1)测试涂布极片的过程中是否开裂(2)冷压时是否断裂，(3)进行本申请所述正极极片柔韧性测试后，在柔韧性二级以下且涂布时不开裂、冷压后不断裂的最大涂布重量。
电池相关性能测试
1.能量密度测定
对实施例和对比例中制备的电池进行称重，得到整个电池的质量；对电池进行容量化成后，25℃电池静置10min后进行0.33C充电至 100％SOC，小电流去极化后静置10min，再进行0.33放电至0％SOC，得到的容量即为电池的0.33C容量。电池静置30min后，充电至100％SOC，再经过静置30min后，0.01C恒电流放电30min，电压有一个平稳的过程，而这一平稳值就是充放电平台，即可得到平台电压；最后计算电池的重量能量密度，即电池质量能量密度＝电池容量×放电平台电压/整个电池的重量，基本单位为Wh/kg(瓦时/千克)。
2.直流电阻(Direct Current Resistance，简称DCR)的测定
在25℃下对电池进行容量测试，容量测试方法如上。然后进行恒压0.05C充电，静置60min，0.33C放电至50％SOC，静置60min，0.33C放电至20％SOC，静置60min，0.33C放电至0％SOC，测试0％SOC的开路电压，整理30s的DCR数据。
测量结果参见表4～7，其中表中的“/”代表没有这一项、未添加或检测不出。
表4-7中，“(I)/(II)/(III)/(IV)”表示结构单元(I)摩尔量/结构单元(II)摩尔量/结构单元(3)摩尔量/结构单元(IV)摩尔量，其中结构单元(I)摩尔量对应于各实施例中前驱体1的摩尔量；结构单元(II)摩尔量对应于各实施例中前驱体2的摩尔量；结构单元(3)摩尔量对应于各实施例中前驱体3的摩尔量；结构单元(IV)摩尔量对应于各实施例中磷酸酯基团的摩尔量。
Figure PCTCN2021133144-appb-000007
Figure PCTCN2021133144-appb-000008
Figure PCTCN2021133144-appb-000009
Figure PCTCN2021133144-appb-000010
Figure PCTCN2021133144-appb-000011
由表7可知，由实施例在单位面积涂布重量基本相同的前提下，具有两个亚层的正极极片对应的电池能量密度较高；进一步地，与所述正极集流体最接近的亚层中的聚醚磷酸酯的重量含量相对于与正极集流体距离最远的亚层中的聚醚磷酸酯的重量含量之比在0～60范围内，当该比例＞60时(实施例26)，影响浆料的稳定性和极片的膜片电阻，电芯的DCR较大。
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 (11)

  1. 一种正极浆料，其特征在于，包括正极活性物质和聚醚磷酸酯，所述聚醚磷酸酯至少包括如下结构单元：
    Figure PCTCN2021133144-appb-100001
    Figure PCTCN2021133144-appb-100002
    以及结构单元(IV)磷酸酯基团，
    其中，
    A为氢、卤素或卤代烷基，所述卤素可选为氟、氯或溴，所述A可选为氢或氟甲基；
    B为羟基、R、OR、或ROR’，其中R、R’各地独立地为含1～8个碳的直链或支链烷基；可选地，B为甲基、乙基或乙氧基甲基；
    E为苯基、烷基取代的苯基、醚代的苯基或卤代苯基，所述E可选为苯基或氟苯基。
  2. 根据权利要求1或2所述的正极浆料，其特征在于，
    所述聚醚磷酸酯的数均分子量范围为10,000～80,000，可选范围为10,000～60,000，更可选范围为30,000～50,000。
  3. 根据权利要求1所述的正极浆料，其特征在于，
    基于结构单元(I)～结构单元(IV)的总摩尔量计，结构单元(I)的摩尔占比为0-75摩尔％，结构单元(II)的摩尔占比为0-65摩尔％，结构单元(III)的摩尔占比为5-65摩尔％，结构单元(IV)的摩尔占比 为4-15摩尔％，其中结构单元(I)和结构单元(II)的摩尔占比不同时为零。
  4. 根据权利要求1～3中任一项所述的正极浆料，其特征在于，所述聚醚磷酸酯与所述正极活性物质的重量比为0.0005～0.030，可选范围为0.001～0.02，更可选范围为0.001～0.01，最可选范围为0.001～0.007。
  5. 根据权利要求1～4中任一项所述的正极浆料，其特征在于，
    所述正极活性物质选自磷酸铁锂、磷酸锰铁锂、锰酸锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、镍酸锂或它们的混合物中的至少一种。
  6. 根据权利要求1～5中任一项所述的正极浆料，其特征在于，
    所述正极浆料的凝胶态因子G范围为0～1，可选范围为0～0.3，
    其中G＝(m1-m2)/m1，G＝0～0.3时，判定浆料不凝胶，G＞0.3时，判定为凝胶；
    m1为采用100目滤网将2kg初始正极浆料过滤10分钟后得到的正极浆料的质量，
    m2为采用100目滤网将2kg的放置48小时的正极浆料过滤10分钟后得到的正极浆料的质量，其中，
    测定m1时使用的所述正极浆料和测定m2时使用的所述正极浆料为同一批正极浆料。
  7. 一种正极极片，其包括
    正极集流体；以及
    位于所述正极集流体至少一个表面的正极膜层，所述正极膜层由权利要求1～6中任一项中所述的正极浆料制备，所述正极膜层在单位面积极片上的质量的范围为13～43mg/cm 2，可选范围为20～43mg/cm 2，更可选范围为22～33mg/cm 2，最可选范围为25～31mg/cm 2，所述质量为极片单个表面上的正极膜层的质量。
  8. 根据权利要求7所述的正极极片，其特征在于，
    所述正极膜层包括两个亚层，所述亚层平行于所述正极集流体且互相叠置，其中与所述正极集流体最接近的亚层中的聚醚磷酸酯的重量含 量相对于与所述正极集流体距离最远的亚层中的聚醚磷酸酯的重量含量之比的范围为0～60，可选范围为0.1～30。
  9. 根据权利要求7或8所述的正极极片，其特征在于，
    通过卷针测量所述正极极片的柔韧性时，
    在卷针直径R≤3.0mm时，所述正极极片不产生裂纹，或者，
    在卷针直径R＝3.0mm时，所述正极极片产生裂纹，但在卷针直径R＝4.0mm时无裂纹。
  10. 根据权利要求7～9中任一项所述的正极极片，其特征在于，
    所述正极极片的浸润率提升率I范围为2～20％，可选范围为6～15％，
    其中I＝(I2-I1)/I1×100％，
    I2为所述正极极片在电解液中的浸润率，
    I1为不包括所述聚醚磷酸酯的正极极片在电解液中的浸润率，
    其中测定I1时使用的正极极片和测定I2时使用的所述正极极片相同，不同之处仅在于测定I1时使用的正极极片中不包括所述聚醚磷酸酯，而测定I2时使用的所述正极极片中含有所述聚醚磷酸酯。
  11. 一种二次电池，其特征在于，包括权利要求7～10中任一项所述的正极极片，或者，通过权利要求1～6中任一项所述的正极浆料获得。
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