WO2023193179A1 - 正极浆料、正极极片及包括所述正极极片的二次电池和电池模块 - Google Patents

正极浆料、正极极片及包括所述正极极片的二次电池和电池模块 Download PDF

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WO2023193179A1
WO2023193179A1 PCT/CN2022/085524 CN2022085524W WO2023193179A1 WO 2023193179 A1 WO2023193179 A1 WO 2023193179A1 CN 2022085524 W CN2022085524 W CN 2022085524W WO 2023193179 A1 WO2023193179 A1 WO 2023193179A1
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positive electrode
slurry
polyether polyol
range
lithium
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PCT/CN2022/085524
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English (en)
French (fr)
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吴启凡
张明
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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 CN202280037364.XA priority Critical patent/CN117378061A/zh
Priority to EP22919272.9A priority patent/EP4280313A1/en
Priority to PCT/CN2022/085524 priority patent/WO2023193179A1/zh
Priority to US18/352,961 priority patent/US20230361303A1/en
Publication of WO2023193179A1 publication Critical patent/WO2023193179A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
    • C08G65/2603—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen
    • C08G65/2606—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups
    • C08G65/2609—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups containing aliphatic hydroxyl groups
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
    • C08L71/02—Polyalkylene oxides
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D171/00—Coating compositions based on polyethers obtained by reactions forming an ether link in the main chain; Coating compositions based on derivatives of such polymers
    • C09D171/02—Polyalkylene oxides
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/24—Electrically-conducting paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/32—Phosphorus-containing compounds
    • C08K2003/321—Phosphates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/32—Phosphorus-containing compounds
    • C08K2003/321—Phosphates
    • C08K2003/324—Alkali metal phosphate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/32—Phosphorus-containing compounds
    • C08K2003/321—Phosphates
    • C08K2003/328—Phosphates of heavy metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/001—Conductive additives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application relates to the technical field of lithium batteries, and in particular to a positive electrode slurry and a positive electrode sheet containing polyether polyol. In addition, this application also relates to a secondary battery and a battery module including the positive electrode sheet.
  • lithium-ion batteries are widely used in energy storage power systems such as hydraulic, thermal, wind 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 to increase their energy density and reduce their costs.
  • the positive electrode plate still needs to be improved.
  • This application was made in view of the above problems, and its purpose is to provide a positive electrode slurry containing a specific polyether polyol, a positive electrode sheet prepared using the positive electrode slurry, and a secondary battery including the positive electrode sheet. and battery modules.
  • the first aspect of the application provides a cathode slurry, which includes a cathode active material and a polyether polyol, and the polyether polyol structural formula is as follows:
  • n1, n2, and n3 are all integers, and their sum is in the range of 1-10;
  • B 1 and B 2 are independently selected from straight bonds, -(CH 2 ) n4 -, where n4 is an integer, and its sum with n1, n2, n3 is in the range of 1-10;
  • R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from -H, hydroxyl, halogen, C 2-10 alkyl, C 2-10 alkoxy, XM, where
  • X is selected from -O-, -S-, -NH-, preferably -O-;
  • M has the following structural formula:
  • n is an integer from 2 to 2000, the optional range is 10 to 2000, and the most optional range is 20 to 1500.
  • D is -H or C 1-8 alkyl
  • Each R is independently selected from H, halogen, hydroxyl, halogenated C 1-8 alkyl, -R 7 , -OR 7 or R 7 OR 8 , where R 7 and R 8 are each independently selected from linear or branched Chain C 1-8 alkyl, phenyl, C 1-8 alkyl substituted phenyl, C 1-8 alkoxy substituted phenyl or halophenyl; each R is independently selected from H, R 7 , phenyl;
  • At least one of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is XM.
  • the energy density of the resulting lithium-ion battery is significantly improved.
  • the amount of battery core can be saved, thereby reducing the total material cost of the battery core.
  • the sum of n1, n2, n3, and n4 is in the range of 2 to 6.
  • the weight average molecular weight of the polyether polyol ranges from 1000 to 80,000, with an optional range from 20,00 to 70,000, and a more optional range from 40,00 to 60,000.
  • the weight average molecular weight of the polyether polyol must be controlled within the above range.
  • the weight ratio of the polyether polyol to the cathode active material is 0.0005 to 0.050, with an optional range of 0.001 to 0.02, a more optional range of 0.001 to 0.01, and a most optional range of 0.001 to 0.001. 0.007.
  • the positive electrode plate When the ratio is too small, the positive electrode plate will crack at high coating weights, and when the ratio is too large, battery performance will be adversely affected.
  • the positive active material is selected from lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, lithium cobalt oxide, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickel oxide or mixtures thereof of at least one.
  • the positive electrode active material is at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, lithium cobalt oxide, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickel oxide or their mixtures
  • the The polyether polyol can better achieve effects such as 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 from 0 to 0.3,
  • G (m1-m2)/m1.
  • m1 is the mass of the cathode slurry obtained after filtering 2kg of the initial cathode slurry for 10 minutes using a 100 mesh filter
  • m2 is the mass of the positive electrode slurry obtained after filtering 2kg of positive electrode slurry for 10 minutes using a 100 mesh filter, where,
  • 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 cathode slurry described in this application is very good.
  • the second aspect of the present application provides a positive electrode plate, which includes
  • a positive electrode film layer is located on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode slurry described in the first aspect of the application.
  • the present application allows the maximum coating weight on the positive electrode sheet to be increased. This is also reflected in the increase in the maximum weight of the positive electrode film layer.
  • the mass of the positive electrode film per unit area ranges from 13 to 31 mg/cm 2 , with an optional range from 22 to 31 mg/cm 2 , and a more optional range from 22 to 29 mg/cm 2 , the mass is the mass of the positive electrode film layer on a single surface of the pole piece. If there are positive electrode film layers on both surfaces of the positive electrode sheet, the mass range of the positive electrode film layer on the positive sheet per unit area is twice the above range, that is, the range is 26 ⁇ 62 mg/cm 2 and the optional range is 44 ⁇ 62 mg/cm 2 , and the optional range is 44 to 58 mg/cm 2 , and the mass is the mass of the positive electrode film layer on both surfaces of the pole piece.
  • the weight of the positive electrode film layer on the positive electrode per unit area is limited to 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 the coating weight is 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 piece does not produce cracks
  • the cold pressing pressure can be reduced, thereby reducing cracks and the risk of band breakage, thereby improving the flexibility of the pole piece.
  • the wetting rate improvement rate I of the positive electrode piece ranges from 2 to 20%, and the optional range is from 6 to 15%.
  • I2 is the infiltration rate of the positive electrode piece in the electrolyte
  • I1 is the wetting rate of the positive electrode sheet excluding the polyether polyol in the electrolyte
  • the positive electrode piece used when measuring I1 is the same as the positive electrode piece used when measuring I2. The only difference is that the positive electrode piece used when measuring I1 does not include the polyether polyol, while the positive electrode piece used when measuring I2 is used.
  • the positive electrode piece contains the polyether polyol.
  • the electrode piece has good wettability, which can achieve good infiltration and liquid retention of the electrolyte, thereby achieving effective infiltration of the electrode piece of the battery core, avoiding insufficient infiltration of the electrode piece, and improving the cell injection efficiency and the stability of the electrode piece during the cycle. wettability, thereby effectively improving battery product performance.
  • the positive electrode sheet described in this application has very good wettability in the electrolyte.
  • a third aspect of the present application provides a secondary battery, which includes the positive electrode sheet described in the second aspect of the present application or is obtained from the positive electrode slurry 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 electrical 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.
  • Figure 1 is a schematic diagram of the principle of the interaction between the polyether polyol in the positive electrode piece of the present application and other substances in the positive electrode piece.
  • the polyether polyol is the polyether polyol described in the present application, and the cathode current collector is Positive electrode current collector aluminum foil, PVDF as the binder.
  • Figure 2 is a schematic diagram of the process of coating cracking caused by capillary tension during the coating process of a positive electrode sheet in the prior art.
  • the active material is the positive active material
  • the force is the force generated during the coating process.
  • the arrows indicate the direction of action of the force; where the polyether polyols described in this application are not used.
  • Figure 3 is a schematic diagram of the positive electrode sheet described in the present application without cracking during the coating process, in which the active material is the positive active material, the acting force is the acting force generated during the coating process, and the arrow indicates the direction of the acting force; and
  • the polyether polyols described in this application are used therein.
  • Figure 4 is a schematic diagram showing the increase in the maximum coating weight per unit area of the positive electrode sheet after using the polyether polyol of the present application, in which the positive electrode material represents the positive active material, SP represents the conductive agent used in the positive electrode sheet, and PVDF represents the positive electrode.
  • Figure 5 is a schematic diagram of the rolling needle used in the flexibility test of the positive electrode piece of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-6.
  • 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" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • the inventor of the present application has designed and synthesized a flexible polymer material polyether polyol.
  • the coating weight can be increased, the coating quality can be improved, and the risks caused by cold pressing and winding can be eliminated. problem while reducing the overall cost of materials used in manufacturing batteries.
  • the first aspect of the application provides a cathode slurry, which includes a cathode active material and a polyether polyol, and the polyether polyol structural formula is as follows:
  • n1, n2, and n3 are all integers, and their sum is in the range of 1-10;
  • B 1 and B 2 are independently selected from straight bonds, -(CH 2 ) n4 -, where n4 is an integer, and its sum with n1, n2, n3 is in the range of 1-10;
  • R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are each independently selected from H, hydroxyl, halogen, C 2-10 alkyl, C 2-10 alkoxy, and XM, where
  • X is selected from -O-, -S-, -NH-, preferably -O-;
  • M has the following structural formula:
  • n is an integer from 2 to 2000, the optional range is 10 to 2000, and the most optional range is 20 to 1500.
  • D is H or C 1-8 alkyl
  • Each R is independently selected from H, halogen, hydroxyl, halogenated C 1-8 alkyl, -R 7 , -OR 7 or R 7 OR 8 , where R 7 and R 8 are each independently selected from linear or branched Chain C 1-8 alkyl, phenyl, C 1-8 alkyl substituted phenyl, C 1-8 alkoxy substituted phenyl or halophenyl; each R can be independently selected from H, -R 7 , phenyl;
  • At least one of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is XM.
  • n1, n2, n3 can each independently be an integer of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; n4 can be 0, 1, 2, 3, 4 , 5, 6, 7, 8, 9 integers.
  • Halogen means fluorine, chlorine, bromine or iodine, preferably fluorine.
  • C 1-8 alkyl is a linear or branched alkyl group containing 1-8 carbons
  • the linear or branched 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-amyl, 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-trimethylbutyl, 2-Methyl
  • C 2-10 alkyl group is a straight-chain or branched-chain alkyl group containing 2-10 carbons
  • C 2-10 alkoxy group is a straight-chain or branched-chain alkoxy group containing 2-10 carbons.
  • the alkyl group in the halogenated C 1-8 alkyl group is optionally selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl tert-butyl, isopentyl, tert-pentyl, neopentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl base, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethyl Pentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 2,2-dimethyl Hexane, 3,3-
  • C 1-8 alkyl-substituted phenyl is C 1-8 alkyl-substituted phenyl.
  • C 1-8 alkoxy-substituted phenyl is C 1-8 alkoxy-substituted phenyl.
  • halophenyl represents a phenyl group substituted by halogen.
  • halogen can be selected from fluorine, chlorine, bromine, and 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.
  • substitutions in the C 1-8 alkyl substituted phenyl, halophenyl, C 1-8 alkoxy substituted phenyl, halo C 1-8 alkyl, etc. described in this application are monosubstituted or Polysubstitution means substitution of more than one substituent, and the substituents may be the same or different.
  • the polyether polyol described in this application contains flexible main chains and branch chains, which can disperse in the cathode slurry and ensure the flexibility of the pole piece; hydrogen bonds are formed between the polymers and on the surface of the polymer and the cathode particles. or covalent bonds to ensure that the positive electrode particles do not migrate during the coating process, as shown in Figure 1; polyether polyol has good compatibility with the electrolyte solvent and does not affect the wettability of the electrolyte to the surface of the positive electrode particles, ensuring Its compatibility; during the cold pressing process, the flexible chain stretches, which reduces the cold pressing pressure, reduces cracks, and reduces the risk of belt breakage.
  • the polyether polyol of the present application is a long flexible chain.
  • the stability of the positive electrode slurry and the flexibility of the positive electrode plate can be improved. properties and ensure the dispersion of various substances in the positive electrode sheet, thereby increasing the coating weight of the positive electrode sheet.
  • the positive electrode slurry of the present application did not crack during the entire coating process.
  • the maximum coating thickness (weight) of the positive electrode sheet is significantly increased.
  • polyether polyol described in this application can be obtained according to conventional technical means in the art, or can be prepared using the following steps:
  • the catalyst can be one of KOH or NaOH
  • the regulator can be one of ethylene glycol or glycerol
  • the acid used for neutralization is sulfuric acid or phosphoric acid
  • the starting agent One or more of propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, xylitol, sorbitol, and mannitol are preferred.
  • the epoxy compound is preferably ethylene oxide, propylene oxide, epichlorohydrin, epoxycyclohexane, cyclobutoxide, tetrahydrofuran, 4-vinyl epoxycyclohexane, and allyl glycidol Ether, epoxystyrene, 1,2-epoxypentane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxy- 1 , 4-butanediol diglycidyl ether, polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glyceryl triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether or cyclic One or more of the oxidized animal and vegetable oils.
  • the weight average molecular weight of the polyether polyol can be controlled by reaction time, catalyst dosage, regulator dosage, initiator dosage, etc.
  • the energy density of the resulting lithium-ion battery is significantly improved.
  • the amount of battery core can be saved, thereby reducing the total material cost of the battery core.
  • the sum of n1, n2, n3, and n4 is in the range of 2 to 6.
  • the weight average molecular weight of the polyether polyol ranges from 1000 to 80,000, with an optional range from 20,00 to 70,000, and a more optional range from 40,00 to 60,000.
  • the molecular weight has an impact on the processing performance of the positive electrode piece.
  • the flexibility of the positive electrode sheet is not significantly improved, and cracking will still occur during coating, and problems such as cold-pressed strip breakage and winding breakage may occur.
  • the molecular weight is too small, the stability of the positive electrode slurry will be poor, physical gelation will occur easily, and the resistance of the positive electrode diaphragm will be degraded, which will also have a negative impact on battery performance.
  • the weight average molecular weight of the polyether polyol must be controlled within the above range. In this application, the weight average molecular weight of the polyether polyol can be determined using gel permeation chromatography.
  • the weight ratio of the polyether polyol to the cathode active material is 0.0005 to 0.050, with an optional range of 0.001 to 0.02, a more optional range of 0.001 to 0.01, and a most optional range of 0.001 to 0.001. 0.007.
  • the weight ratio of the polyether polyol to the positive active material is 0.0005 to 0.050. When the ratio is too small, the positive electrode plate will crack at high coating weights, and when the ratio is too large, battery performance will be adversely affected.
  • the positive active material is selected from lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, lithium cobalt oxide, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickel oxide or mixtures thereof of at least one.
  • the present application can use any positive active material for batteries known in the art.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon.
  • At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the inventor of the present application found that when the positive electrode active material is lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, lithium cobalt oxide, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickel oxide or a mixture thereof, When at least one of the polyether polyols is added, the effects of improving the flexibility of the pole piece and increasing the maximum coating weight of the pole piece can be better achieved.
  • the gel state factor G of the cathode slurry ranges from 0 to 1, and optionally ranges from 0 to 0.3.
  • G (m1-m2)/m1.
  • m1 is the mass of the cathode slurry obtained after filtering 2kg of the initial cathode slurry for 10 minutes using a 100 mesh filter
  • m2 is the mass of the positive electrode slurry obtained after filtering 2kg of positive electrode slurry for 10 minutes using a 100 mesh filter, where,
  • 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 cathode slurry described in this application is very good.
  • the second aspect of the present application provides a positive electrode plate, which includes
  • a positive electrode film layer is located on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode slurry described in the first aspect of the application.
  • the present application allows the maximum coating weight on the positive electrode sheet to be increased. This is also reflected in the increase in the maximum weight of the positive electrode film layer.
  • the mass of the positive electrode film layer per unit area of the positive sheet ranges from 13 to 31 mg/cm 2 , with an optional range from 22 to 31 mg/cm 2 , and a more optional range from 22 to 29 mg/cm 2 , the mass is the mass of the positive electrode 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 area is twice the above range, that is, the range is 26 ⁇ 62 mg/cm 2 and the optional range is 44 ⁇ 62 mg/cm 2 , and the optional range is 44 to 58 mg/cm 2 , and the mass is the mass of the positive electrode film layer on both surfaces of the pole piece.
  • the coating weight per unit area of the positive electrode sheet can reach a maximum of 31 mg/cm 2 , optionally, the coating weight per unit area of the positive electrode sheet can reach a maximum of 31 mg/cm 2 Can be in the range of 23-31mg/ cm2 .
  • the weight of the positive electrode film layer on the positive electrode per unit area is limited to the above range to ensure that the best effect can be achieved within this range.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the mass content of the positive active material in the positive electrode film layer is 90-97%, based on the positive electrode film layer.
  • the content can be measured using energy dispersive X-ray spectroscopy (EDS) or inductively coupled plasma spectroscopy (ICP).
  • EDS energy dispersive X-ray spectroscopy
  • ICP inductively coupled plasma spectroscopy
  • the mass content of the adhesive in the positive electrode film layer is 2 to 5%, based on the total mass of the positive electrode film layer.
  • the adhesive 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 positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the positive electrode sheet can be prepared by dispersing the above-mentioned components used to prepare the positive electrode sheet, such as positive active material, conductive agent, adhesive and any other components 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 piece 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 is 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 may include two sub-layers, the sub-layers being parallel to the positive electrode current collector and overlapping each other, wherein the sub-layer closest to the positive electrode current collector (i.e. , the weight content of the polyether polyol in the sublayer closest to the current collector) relative to the weight content of the polyether polyol in the sublayer farthest from the positive electrode current collector (i.e., the sublayer far away from the current collector)
  • the weight content ratio ranges from 0 to 60, and the optional range is from 0 to 40.
  • the weight ratio of the polyether polyol to the positive active material in the sub-layer close to the current collector, is 0 to 0.043; in the sub-layer far away from the current collector, the weight ratio of the polyether polyol to the positive active material is 0 to 0.043; The weight ratio of the ether polyol to the positive active material is 0.0006 to 0.004.
  • the coating weight is above 23mg/ cm2 , compared with a single thick coating, multiple coatings can reduce the material cost of the flexible additive, and at the same time, the polyether polyol described in this application can function better and Does not affect the electrical performance of secondary batteries.
  • the positive electrode piece does not produce cracks
  • the positive electrode piece according to the present application when measuring the flexibility of the positive electrode piece through a rolling needle, prepare a pole piece sample with a length and width of 50 mm ⁇ a length of 100 mm, and use a special rolling needle to measure the flexibility of the positive electrode piece. Winding is carried out, and the cracks of the pole pieces are observed using a combination of visual inspection and a microscope. Determine flexibility level according to the following method:
  • the diameter of the rolling needle is R
  • R 5.0mm has no cracks
  • R 6.0mm has no cracks
  • Rolling needles are prepared as follows:
  • the formed hydrogen bonds are destroyed and the flexible backbone stretches.
  • the cold pressing pressure can be reduced, thereby reducing cracks and reducing the risk of belt breakage.
  • the infiltration rate improvement rate I of the positive electrode piece ranges from 2 to 20%, and the optional range is from 6 to 15%.
  • I2 is the infiltration rate of the positive electrode piece in the electrolyte
  • I1 is the wetting rate of the positive electrode sheet excluding the polyether polyol in the electrolyte
  • the positive electrode piece used when measuring I1 is the same as the positive electrode piece used when measuring I2. The only difference is that the positive electrode piece used when measuring I1 does not include the polyether polyol, while the positive electrode piece used when measuring I2 is used.
  • the positive electrode piece contains the polyether polyol.
  • the electrode piece has good wettability, which can achieve good infiltration and liquid retention of the electrolyte, thereby achieving effective infiltration of the electrode piece of the battery core, avoiding insufficient infiltration of the electrode piece, and improving the cell injection efficiency and the stability of the electrode piece during the cycle. wettability, thereby effectively improving battery product performance.
  • the positive electrode sheet described in this application has very good wettability in the electrolyte.
  • a 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 obtained by 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 total material cost is reduced when preparing the battery.
  • the secondary battery, battery module, battery pack and power device of the present application will be described below.
  • a secondary battery typically includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the positive electrode sheet described in the second aspect of the present application or the positive electrode sheet prepared according to the positive electrode slurry described in the first aspect of the present application is used.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, phosphorus-based materials, tin-based materials, lithium titanate, and the like.
  • the phosphorus-based material may be selected from at least one of elemental phosphorus, phosphorus oxide compounds, phosphorus carbon composites, phosphorus nitrogen composites and phosphorus alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes an adhesive.
  • the adhesive may be selected from the group consisting of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyacrylic acid sodium (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polyacrylamide At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, adhesives and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application there is no specific restriction on the type of electrolyte in this application, and it can be selected according to needs.
  • the electrolyte may be selected from at least one of a solid electrolyte and a liquid electrolyte (ie, electrolyte).
  • the electrolyte is an electrolyte solution.
  • the electrolyte solution includes electrolyte salts and solvents.
  • the electrolyte salt can be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), bisfluorosulfonyl Lithium amine (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium difluoromethane borate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium perchlor
  • 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), methylpropyl carbonate (MPC), ethylpropyl 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) , one or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl s
  • EC
  • additives are optionally included in the electrolyte.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, and additives that improve the low-temperature performance of the battery. Additives etc.
  • the secondary battery further includes a separator film.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play an isolation role.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the secondary battery may include an outer package for packaging the positive electrode tab, the negative electrode tab, and the electrolyte.
  • the positive electrode sheet, the negative electrode sheet and the separator film can be laminated or rolled to form a laminated structure cell or a wound structure cell, and the cell is packaged in an outer package; the electrolyte can be electrolyte, and the electrolyte is infiltrated in the battery core.
  • the number of cells in the secondary battery can be one or several, and can be adjusted according to needs.
  • the present application provides an electrode assembly.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a soft bag, such as a pouch-type soft bag.
  • the soft bag may be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the present application provides a method for preparing a secondary battery, in which the negative electrode sheet described in the present application or the negative electrode sheet prepared according to the method described in the present 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 piece, the isolation film, and the negative electrode piece can be wound or laminated in order, so that the isolation film plays an isolation role between the positive electrode piece and the negative electrode piece, thereby obtaining a battery core.
  • the battery core is placed in the outer package, electrolyte is injected and sealed to obtain a 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 adhesive can be dispersed in a solvent (such as N-methylpyrrolidone, NMP for short) 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 piece is obtained.
  • a solvent such as N-methylpyrrolidone, NMP for short
  • the preparation of a secondary battery includes the step of preparing a negative electrode plate according to the method described herein.
  • This application has no particular limitation on the shape of the secondary battery, which can be cylindrical, square or any other shape.
  • the present application provides an electrical device, a battery module or a battery pack, wherein the electrical device, battery module or battery pack includes a secondary battery as described in the present application or a secondary battery as described in the present application. secondary battery prepared by the method.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application.
  • the secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • the present application provides a battery module including the secondary battery described in the present application.
  • this application also provides a battery pack, which includes the above-mentioned battery module.
  • This application further provides an electrical device, which includes at least one of the secondary battery described in this application, the above-mentioned battery module, or the above-mentioned battery pack.
  • Step 2 Preparation of cathode slurry
  • the positive electrode slurry prepared in step 2 is coated on both surfaces of the positive electrode current collector aluminum foil, and then dried and cold pressed to obtain the positive electrode sheet. After a series of positive electrode performance tests, the maximum coating weight per unit area is 31 mg/cm 2 .
  • the process of testing the performance of the positive electrode sheet used to determine the maximum coating weight per unit area is as follows:
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • PE polyethylene
  • the outer packaging is a hard-shell case with a length ⁇ width ⁇ height of 148mm ⁇ 28.5mm ⁇ 97.5mm.
  • the secondary batteries of Examples 2-8 were prepared in a similar manner to Example 1, except for the reaction time of the polyether polyol in step 1. See Table 1 for details.
  • the secondary batteries of Examples 9-10 were prepared in a similar manner to Example 1, except that propylene glycol and glycerol were used as initiators in the preparation of the polyether polyol in step 1. See Table 1 for details.
  • the secondary battery of Comparative Example 1 was prepared in a similar manner to Example 1, except that no polyether polyol was added, that is, there was no step 1, and no polyether polyol was added in step 2.
  • Examples 11 to 17 were prepared in a similar manner to Example 1, except that the amounts of the positive active material lithium iron phosphate and the amount of polyether polyol in step 2 were used. See Table 2 for details.
  • the gel state of the cathode slurry is evaluated by the following method:
  • m1 is the mass of the cathode slurry obtained after filtering 2kg of the initial cathode slurry for 10 minutes using a 200 mesh filter.
  • m2 is the mass of the positive electrode slurry obtained after filtering 2kg of positive electrode slurry for 10 minutes using a 200 mesh filter, where,
  • 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 is in the range of 0 to 0.3, it is judged not to be a gel; if G>0.3, it is judged to be a gel.
  • test method is as follows:
  • the diameter of the rolling needle is R
  • R 5.0mm has no cracks
  • R 6.0mm has no cracks
  • I2 is the infiltration rate of the positive electrode piece in the electrolyte
  • I1 is the wetting rate of the positive electrode sheet excluding the polyether polyol in the electrolyte
  • the positive electrode piece used when measuring I1 is the same as the positive electrode piece used when measuring I2. The only difference is that the positive electrode piece used when measuring I1 does not include the polyether polyol, while the positive electrode piece used when measuring I2 is used.
  • the positive electrode piece contains the polyether polyol.
  • the capillary method was used to test the liquid absorption rate of the electrode piece.
  • Prepare a pole piece with a size of ⁇ 50mm*50mm, with a smooth surface without wrinkles and no peeling off powder; select a capillary with an inner diameter of d 100um and polish it with sandpaper until the port is neat.
  • use a stopwatch to record the time.
  • When the liquid level has dropped read the washing time and record the data t.
  • the electrolyte infiltration rate ⁇ ⁇ ( d/2) 2 ⁇ h ⁇ /t, where ⁇ is 3.14 and ⁇ is the electrolyte density.
  • the coating weight per unit area can be obtained by subtracting the average mass of the empty aluminum foil wafers from the average mass of the flakes and dividing by 2.
  • the “single side” refers to coating on only one surface of the current collector, and is not the same concept as the number of "sub-layers" mentioned earlier in this application.
  • the maximum coating weight per unit area in the table refers to the single-sided weight.
  • the coating weight data in the examples of this application form all refer to the data of the maximum coating weight per unit area of a single surface.
  • the pole piece performance and battery performance are both measured at the maximum coating weight.
  • the maximum coating weight per unit area refers to the maximum coating weight after conducting the following tests:
  • the basic unit is Wh/kg (watt hour/kilogram).
  • the capacity test was performed on the batteries prepared in each example at 25°C.
  • the capacity test method was as above. Then charge at a constant voltage of 0.05C, let it sit for 60min, discharge to 50% SOC at 0.33C, let it stand for 60min, discharge to 20%SOC at 0.33C, let it stand for 60min, discharge at 0.33C to 0%SOC, and test the open circuit of 0%SOC. Voltage, organize 30s of DCR data.

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Abstract

本发明提供一种包括聚醚多元醇的正极浆料，所述聚醚多元醇结构式如下：其中，n1、n2、n3、R1、R2、R3、R4、R5、R6、B1、B2如说明书中所定义。添加本申请所述的聚醚多元醇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和电池模块 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多元醇的正极浆料和正极极片；此外，本申请还涉及包括所述正极极片的二次电池和电池模块。
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多元醇的正极浆料、使用所述正极浆料制备的正极极片以及包括所述正极极片的二次电池和电池模块。
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多元醇，所述聚醚多元醇结构式如下：
Figure PCTCN2022085524-appb-000001
其中，
n1、n2、n3均为整数，其总和在1-10的范围内；
B 1、B 2各地独立地选自直键、-(CH 2) n4-，其中n4为整数，其与n1、n2、n3之和在1-10的范围内；
R 1、R 2、R 3、R 4、R 5、R 6各自独立地选自-H、羟基、卤素、C 2-10烷基、C 2-10烷氧基、XM，其中
X选自-O-、-S-、-NH-，优选-O-；
M具有以下结构式：
-(CH 2-CHR-O) nD   式2
其中，
n为2～2000的整数，可选范围为10～2000，最可选范围为20～1500，
D为-H或C 1-8烷基，
每个R独立地选自H、卤素、羟基、卤代C 1-8烷基、-R 7、-OR 7或R 7OR 8，其中R 7、R 8各自独立地选自直链或支链的C 1-8烷基、苯基、C 1-8烷基取代的苯基、C 1-8烷氧基取代的苯基或卤代苯基；每个R独立地可选为H、R 7、苯基；
R 1、R 2、R 3、R 4、R 5、R 6中至少一个为XM。
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多元醇后，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。
在任意实施方式中，在所述聚醚多元醇的结构式中，n1、n2、n3、n4的总和在2～6的范围内。
在任意实施方式中，所述聚醚多元醇的重均分子量范围为1000～80,000，可选范围为20,00～70,000，更可选范围为40,00～60,000。
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，则不利于聚醚多元醇在正极浆料中的分散。因此，所述聚醚多元醇的重均分子量须控制上上述范围内。
所述的聚醚多元醇与正极活性物质、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。
在任意实施方式中，所述聚醚多元醇与所述正极活性物质的重量比为0.0005～0.050，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。
在任意实施方式中，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，添加所述聚醚多元醇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。
在任意实施方式中，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，通过添加所述聚醚多元醇，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。
在任意实施方式中，所述正极膜层在单位面积极片上的质量的范围为13-31mg/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26～62mg/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。
在任意实施方式中，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多元醇后，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。
在任意实施方式中，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为不包括所述聚醚多元醇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多元醇，而测定I2时使用的所述正极极片中含有所述聚醚多元醇。
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，包括本申请第二方面所述的正极极片或由本申请第一方面所述的正极浆料获得。
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多元醇与正极极片中其他物质之间相互作用的原理示意图，其中聚醚多元醇为本申请所述的聚醚多元醇，其中的阴极集流体为正极集流体铝箔，PVDF为粘接剂。
图2为现有技术中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产生的作用力，箭头表示作用力的作用方向；其中不使用本申请所述的聚醚多元醇。
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产生的作用力，箭头表示作用力的作用方向；并且其中使用了本申请所述的聚醚多元醇。
图4为在使用本申请的聚醚多元醇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接剂；其中X表示不包含聚醚多元醇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多元醇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)。
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多元醇，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多元醇，所述聚醚多元醇结构式如下：
Figure PCTCN2022085524-appb-000002
其中，
n1、n2、n3均为整数，其总和在1-10的范围内；
B 1、B 2各地独立地选自直键、-(CH 2) n4-，其中n4为整数，其与n1、n2、n3之和在1-10的范围内；
R 1、R 2、R 3、R 4、R 5、R 6各自独立地选自H、羟基、卤素、C 2-10烷基、C 2-10烷氧基、XM，其中
X选自-O-、-S-、-NH-，优选-O-；
M具有以下结构式：
-(CH 2-CHR-O) nD   式2
其中，
n为2～2000的整数，可选范围为10～2000，最可选范围为20～1500，
D为H或C 1-8烷基，
每个R独立地选自H、卤素、羟基、卤代C 1-8烷基、-R 7、-OR 7或R 7OR 8，其中R 7、R 8各自独立地选自直链或支链的C 1-8烷基、苯基、C 1-8烷基取代的苯基、C 1-8烷氧基取代的苯基或卤代苯基；每个R可独立地选自H、-R 7、苯基；
R 1、R 2、R 3、R 4、R 5、R 6中至少一个为XM。
可选地，n1、n2、n3各自独立地可为0、1、2、3、4、5、6、7、8、9、10的整数；n4可为0、1、2、3、4、5、6、7、8、9的整数。
卤素表示氟、氯、溴或碘，优选氟。
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 2-10烷基为含2-10个碳的直链或支链烷基；C 2-10烷氧基为含2-10个碳的直链或支链烷氧基。
本申请中，卤代C 1-8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C 1-8烷基中的卤素可选自氟、氯、溴、碘。
本申请中，C 1-8烷基取代的苯基为C 1-8烷基取代的苯基。C 1-8烷氧基取代的苯基为C 1-8烷氧基取代的苯基。
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。
本申请中所述的C 1-8烷基取代的苯基、卤代苯基、C 1-8烷氧基取代的苯基、卤代C 1-8烷基等中的取代为单取代或多取代，多取代意指不止一个取代基的取代，取代基可相同或不同。
本申请所述的聚醚多元醇含有柔性主链和支链，在正极浆料中分散作用，同时也可保证极片的柔韧性；该聚合物之间、聚合物与正极颗粒表面形成氢键或共价键，保证正极颗粒在涂布过程中不迁移，如图1所示；聚醚多元醇与电解液溶剂具有良好的相容性，不影响电解液对正极颗粒表面的浸润性，保证其兼容性；冷压过程中，柔性链伸展，表现为降低冷压压力，减少裂纹，减少断带风险。本申请的聚醚多元醇为长的柔性链，通过向正极浆料中加入柔性添加剂，即，本申请所述的聚醚多元醇，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，在添加了所述聚醚多元醇后，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多元醇后，正极极片中的最大涂布厚度(重量)明显提高。
本申请所述的聚醚多元醇可根据本领域常规技术手段获得，也可使用以下步骤制备：
将催化剂、调节剂、起始剂及环氧化合物加入到高压反应釜内，在20℃～200℃下反应1～30h，压力为-0.1～0.5MPa，得到粗聚醚多元醇，后经中和反应、脱气、吸附和真空抽滤得到聚醚多元醇成品。 所述的催化剂可为KOH或NaOH中的一种，所述的调节剂可为乙二醇或者丙三醇中一种，所述中和所用的酸为硫酸或磷酸；所述的起始剂优选丙二醇、乙二醇，二乙二醇、二丙二醇、甘油、三羟甲基丙烷、季戊四醇、二季戊四醇、木糖醇、山梨醇、甘露醇中的一种或多种。所述的环氧化合物优选为环氧乙烷、环氧丙烷、环氧氯丙烷、环氧环己烷、环丁氧烷、四氢呋喃、4-乙烯基环氧环己烷、烯丙基缩水甘油醚、环氧苯乙烯、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、环氧氟丙烷、环氧氯丙烷、环氧溴丙烷烷基取代氧化苯乙烯、双酚A型环氧树脂、苯酚型酚醛树脂、双酚S型环氧树脂、1,4-丁二醇二缩水甘油醚、聚丙二醇二缩水甘油醚、聚乙二醇二缩水甘油醚、甘油三缩水甘油醚、三羟甲基丙烷三缩水甘油醚、季戊四醇四缩水甘油醚或环氧化动植物油中的一种或多种。
所述的聚醚多元醇的重均分子量，可通过反应时间、催化剂用量、调节剂用量、起始剂用量等进行控制。
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多元醇后，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，在所述聚醚多元醇的结构式中，n1、n2、n3、n4的总和在2～6的范围内。
在一些实施方式中，所述聚醚多元醇的重均分子量范围为1000～80,000，可选范围为20,00～70,000，更可选范围为40,00～60,000。
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，则不利于聚醚多元醇在正极浆料中的分散。因此，所述聚醚多元醇的重均分子量须控制上上述范围内。本申请中，聚醚多元醇的重均分子量可以使用凝胶渗透色谱法进行测定。
在一些实施方式中，所述聚醚多元醇与所述正极活性物质的重量比为0.0005～0.050，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。
所述聚醚多元醇与所述正极活性物质的重量比为0.0005～0.050。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，添加所述聚醚多元醇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，通过添加所述聚醚多元醇，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13-31mg/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26～62mg/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多元醇之后，正极极片上单位面积的涂布重量最大可达31mg/cm 2，可选地，正极极片上单位面积的涂布重量最大可在23-31mg/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X射线能谱分析(EDS)或者电感耦合等离子光谱发生仪(ICP)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，粘接剂和导电剂不足，导致电池性能差。
在所述正极极片中，在正极膜层中的粘接剂质量含量为2～5％，基于正极膜层的总质量计。作为示例，所述粘接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接剂，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接剂，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、粘接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。
在一些可选实施方式中，所述正极膜层可以包括两个亚层，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)中的聚醚多元醇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)中的聚醚多元醇的重量含量之比的范围为0～60，可选范围为0～40。在一些可选实施方式中，离集流体近的亚层中，所述聚醚多元醇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，所述聚醚多元醇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多元醇可以更好地发挥作用而不影响二次电池的电性能。
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多元醇的正极浆料，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多元醇后，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为不包括所述聚醚多元醇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多元醇，而测定I2时使用的所述正极极片中含有所述聚醚多元醇。
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获得。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的正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、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接剂。所述粘接剂可选自丁苯橡胶(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、粘接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、导电剂和粘接剂分散于溶剂(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
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过 市购获得的常规产品。
实施例1
步骤1：聚醚多元醇的制备
将25g作为催化剂的氢氧化钠、18g作为调节剂的丙三醇、1000g作为起始剂的山梨醇和5000g的环氧丙烷加入到高压反应釜内，在100℃下反应10h，压力为0.15MPa，得到粗制的聚醚多元醇。然后经中和反应、脱气、吸附和真空抽滤得到重均分子量为40000的聚醚多元醇成品。重均分子量根据凝胶渗透色谱法测试。
步骤2：正极浆料的制备
将6279g正极活性物质(磷酸铁锂)、65g导电剂(导电炭黑Super P)、130g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3500g NMP中，并搅拌180min以使其均匀分散。最后加入26g步骤1中制备的聚醚多元醇，再充分搅拌60min，使其形成均匀的正极浆料。
步骤3：正极极片的制备
将步骤2中制备的正极浆料涂覆于正极集流体铝箔的两个表面上，然后进行干燥、冷压，之后得到正极极片。经一系列正极极片性能测试，单位面积最大涂布重量为31mg/cm 2。
确定单位面积最大涂布重量时使用的正极极片性能测试的过程如下：
(1)测试涂布极片的过程中是否开裂，不开裂的话继续进行下一个测试；
(2)冷压时是否断裂，不断裂的话继续进行柔韧性测试；
(3)进行本申请所述正极极片柔韧性测试，测试结果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为本申请实施例中的最大涂布重量。
步骤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。
步骤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。
步骤6：隔离膜
采用聚乙烯(PE)薄膜。
步骤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2-8
以与实施例1类似的方式制备实施例2-8的二次电池，不同之处在于步骤1中聚醚多元醇的反应时间。详情参见表1。
实施例9-10
以与实施例1类似的方式制备实施例9-10的二次电池，不同之处在于步骤1中聚醚多元醇的制备中使用了丙二醇和丙三醇作为引发剂。详情参见表1。
对比例1
以与实施例1类似的方式制备对比例1的二次电池，不同之处在于不添加聚醚多元醇，即没有步骤1，且步骤2中不添加聚醚多元醇。
表1：聚醚多元醇制备
Figure PCTCN2022085524-appb-000003
Figure PCTCN2022085524-appb-000004
实施例11-17
以与实施例1类似的方式制备实施例11-17，不同之处在于步骤2中正极活性材料磷酸铁锂的用量和聚醚多元醇的用量。详情参见表2。
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 聚醚多元醇所用克数
实施例1 磷酸铁锂 6279.00 26.00
实施例11 磷酸铁锂 6301.75 3.25
实施例12 磷酸铁锂 6110.00 195.00
实施例13 磷酸铁锂 6298.50 6.50
实施例14 磷酸铁锂 6175.00 130.00
实施例15 磷酸铁锂 6259.50 45.50
实施例16 磷酸铁锂 6292.00 1.30
实施例17 磷酸铁锂 6272.50 325.0
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为不包括所述聚醚多元醇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多元醇，而测定I2时使用的所述正极极片中含有所述聚醚多元醇。
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＝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，而与本申请前文所述的“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。
如前所述，单位面积最大涂布重量是指在进行以下测试后的最大涂布重量：
(1)测试涂布极片的过程中是否开裂，不开裂的话继续进行下一个测试；
(2)冷压时是否断裂，不断裂的话继续进行柔韧性测试；
(3)进行本申请所述正极极片柔韧性测试，测试结果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为本申请实施例中的最大涂布重量。
电池相关性能测试
1.能量密度测定
对各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℃下对各实施例中制备的电池进行容量测试，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3～5，其中表中的“/”代表没有这一项、未添加或检测不出。
表3：添加聚醚多元醇和未添加聚醚多元醇对比
Figure PCTCN2022085524-appb-000005
由表3可知，与未添加聚醚多元醇的对比例1相比，实施例1中的正极浆料中在添加聚醚多元醇后，单位面积涂布重量提升41％，能量密度提升5％，电池性能得到明显改善。
Figure PCTCN2022085524-appb-000006
Figure PCTCN2022085524-appb-000007
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 (10)

  1. 一种正极浆料，其特征在于，包括正极活性物质和聚醚多元醇，所述聚醚多元醇结构式如下：
    Figure PCTCN2022085524-appb-100001
    其中，
    n1、n2、n3均为整数，其总和在1-10的范围内；
    B 1、B 2各地独立地选自直键、-(CH 2) n4-，其中n4为整数，其与n1、n2、n3之和在1-10的范围内；
    R 1、R 2、R 3、R 4、R 5、R 6各自独立地选自H、羟基、卤素、C 2-10烷基、C 2-10烷氧基、XM，其中
    X选自-O-、-S-、-NH-，优选-O-；
    M具有以下结构式：
    -(CH 2-CHR-O) nD  式2
    其中，
    n为2～2000的整数，可选范围为10～2000，最可选范围为20～1500，
    D为H或C 1-8烷基，
    每个R独立地选自H、卤素、羟基、卤代C 1-8烷基、-R 7、-OR 7或R 7OR 8，其中R 7、R 8各自独立地选自直链或支链的C 1-8烷基、苯基、C 1-8烷基取代的苯基、C 1-8烷氧基取代的苯基或卤代苯基；每个R独立地可选为H、R 7、苯基；
    R 1、R 2、R 3、R 4、R 5、R 6中至少一个为XM。
  2. 根据权利要求1所述的正极浆料，其特征在于，n1、n2、n3、n4的总和在2～6的范围内。
  3. 根据权利要求1或2所述的正极浆料，其特征在于，所述聚醚多元醇的重均分子量范围为1000～80,000，可选范围为20,00～70,000，更可选范围为40,00～60,000。
  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，所述聚醚多元醇与所述正极活性物质的重量比为0.0005～0.050，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13～42mg/cm 2，可选范围为22～31mg/cm 2，更可选范围为22～29mg/cm 2，最可选范围为25～29mg/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，
    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。
  9. 根据权利要求7或8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为不包括所述聚醚多元醇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多元醇，而测定I2时使用的所述正极极片中含有所述聚醚多元醇。
  10. 一种二次电池，其特征在于，包括权利要求7～9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的正极极片。
PCT/CN2022/085524 2022-04-07 2022-04-07 正极浆料、正极极片及包括所述正极极片的二次电池和电池模块 WO2023193179A1 (zh)

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