WO2022001429A1 - 一种正极极片及含该正极极片的二次电池 - Google Patents

一种正极极片及含该正极极片的二次电池 Download PDF

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WO2022001429A1
WO2022001429A1 PCT/CN2021/094181 CN2021094181W WO2022001429A1 WO 2022001429 A1 WO2022001429 A1 WO 2022001429A1 CN 2021094181 W CN2021094181 W CN 2021094181W WO 2022001429 A1 WO2022001429 A1 WO 2022001429A1
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positive electrode
formula
segment
polymer
lithium
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PCT/CN2021/094181
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English (en)
French (fr)
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唐伟超
李素丽
赵伟
袁号
刘春洋
李俊义
徐延铭
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珠海冠宇电池股份有限公司
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Publication of WO2022001429A1 publication Critical patent/WO2022001429A1/zh
Priority to US18/065,616 priority Critical patent/US20230114916A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/137—Electrodes based on electro-active polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0082—Organic polymers
    • 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 invention relates to the technical field of secondary batteries, in particular to a positive electrode piece and a secondary battery containing the positive electrode piece.
  • Lithium-ion batteries have the advantages of long cycle life, high energy density, and environmental protection. They have been used in energy storage, power, and digital fields. With the urgent market demand for high-energy-density batteries, it is increasingly difficult for traditional lithium-ion battery systems to meet market demand.
  • Lithium-ion batteries are mainly composed of positive electrodes, negative electrodes, separators, and electrolytes. The electrolytes are mainly composed of organic solvents. In high-energy-density battery systems, the batteries have safety problems such as liquid leakage, fire, and explosion. Solid-state batteries are expected to fundamentally improve the safety performance of lithium-ion batteries, and have received extensive attention at home and abroad.
  • Solid-state batteries are strong contenders for next-generation high-energy-density energy storage batteries.
  • all-solid-state electrolytes also face the problem of excessive interface contact resistance, especially on the positive side, which greatly restricts the application of all-solid-state electrolytes.
  • solid electrolytes mainly include sulfide electrolytes, oxide electrolytes, polymer electrolytes, hydride electrolytes, etc.
  • sulfide electrolytes have disadvantages such as high interface impedance and unstable performance
  • oxide electrolytes have disadvantages such as low conductivity and poor interface contact.
  • Hydride electrolytes have the disadvantages of unstable performance, flammability and explosion
  • polymer electrolytes have the characteristics of good processing performance and low room temperature conductivity.
  • the purpose of the present invention is to provide a positive electrode sheet and a secondary battery containing the positive electrode sheet.
  • the positive electrode piece of conventional all-solid-state battery mainly contains positive electrode active material, conductive agent, binder and solid electrolyte.
  • the cloth is placed on the surface of the current collector, and after drying and cutting treatment, a positive electrode piece for a solid-state battery is obtained, and the positive electrode piece, the solid electrolyte, and the negative electrode piece are laminated to obtain a solid-state lithium ion battery.
  • problems such as poor interfacial contact between the pole piece and the solid electrolyte, and high porosity on the surface of the pole piece, which greatly affects the cycle performance of the solid-state battery.
  • a positive electrode sheet the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer coated on one side or both sides of the positive electrode current collector, the positive electrode active material layer comprises a positive electrode active material, a conductive agent and a polymer
  • An electrolyte wherein the polymer electrolyte includes a polymer and a lithium salt, and the polymer includes a repeating unit shown in the following formula 1:
  • R 1 is selected from H or C 1-6 alkyl
  • R 2 is selected from connecting group
  • R 3 is selected from end-capping group
  • M is selected from polyphenylene ether segment, polyethylene glycol segment, poly Ethylenedithiol segment, polycarbonate segment, polypropylene glycol segment or polysilyl ether segment.
  • R 1 is selected from H or C 1-3 alkyl
  • R 2 is Hydroxyl in The linking group formed after the reaction of R 3 'in
  • R 3 and R 3 ' are the same or different, independently selected from H, OH, COOH, NH 2 , and cannot be H at the same time.
  • the polyphenylene ether segment has repeating units shown in formula 2:
  • R 4 is selected from H or C 1-6 alkyl, and m is an integer between 0-4.
  • R 4 is selected from H or C 1-3 alkyl, and m is an integer between 0-2;
  • the polyethylene glycol segment has a repeating unit shown in formula 3:
  • the polypropylene glycol segment has a repeating unit shown in formula 4:
  • the polyethylene dithiol segment has a repeating unit shown in formula 5:
  • the polycarbonate segment has a repeating unit shown in formula 6:
  • the polysiloxane segment has a repeating unit shown in formula 7:
  • the polymer is selected from polyphenylene oxide polyacrylate, polyethylene glycol polymethyl methacrylate, polyethylene dithiol polymethyl methacrylate, polycarbonate polyacrylate, polypropylene glycol polyacrylate At least one of methacrylate, polysilyl ether and polymethyl methacrylate.
  • the monomer for preparing the polymer is selected from the compounds shown in the following formula 8:
  • R 1 , R 2 , R 3 , and M are defined as described above.
  • the compound represented by the formula 8 is selected from polyphenylene ether acrylate, polyethylene glycol methyl methacrylate, polycarbonate acrylate, polypropylene glycol methacrylate, lithium polysulfonate methacrylate , at least one of polysilyl ether methyl methacrylate.
  • the positive electrode active material layer comprises the following components by mass percentage: 70-95wt% of the positive electrode active material, 2-15wt% of the conductive agent, 3-28wt% of the above-mentioned polymer electrolyte, 0- 10 wt% binder.
  • the molar ratio of other elements in the polymer except carbon and hydrogen to the lithium element in the lithium salt is 5:1-25:1, such as 5:1, 10:1 , 15:1, 20:1, 25:1, wherein the other elements other than carbon and hydrogen may be oxygen, sulfur or silicon, for example.
  • the porosity of the positive electrode sheet is 0%-5%; and/or the elongation elongation ratio of the positive electrode active material layer in the positive electrode sheet is 5%-500%.
  • the present invention also provides a solid-state battery, the solid-state battery includes the above-mentioned positive electrode plate.
  • the present invention provides a positive electrode piece and a secondary battery containing the positive electrode piece.
  • a polymer electrolyte prepared by a type of polymer different from the prior art is selected as the solid electrolyte in the positive electrode plate, and the solid electrolyte has both a binding function and a lithium conducting function, and can replace the existing electrode plate.
  • the binder and solid electrolyte in the lithium ion can effectively improve and enhance the transport performance of lithium ions and reduce the internal resistance of the battery.
  • the porosity of the positive electrode sheet containing the solid electrolyte is low, about 5% or less, which greatly reduces the voids and pores inside the positive electrode sheet, increases the content of positive active material per unit volume, and improves lithium ions and electrons. It can effectively improve the energy density, cycle performance and rate performance of the battery.
  • the positive pole piece containing the solid electrolyte can be applied to high energy density battery system, which broadens its application field.
  • the present invention provides a positive electrode sheet
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one side or both sides of the positive electrode current collector
  • the positive electrode active material layer includes a positive electrode Active material, conductive agent and polymer electrolyte, wherein the polymer electrolyte includes a polymer and a lithium salt, and the polymer includes a repeating unit shown in the following formula 1:
  • R 1 is selected from H or C 1-6 alkyl
  • R 2 is selected from connecting group
  • R 3 is selected from end-capping group
  • M is selected from polyphenylene ether segment, polyethylene glycol segment, poly Ethylenedithiol segment, polycarbonate segment, polypropylene glycol segment or polysilyl ether segment.
  • R 1 is selected from H or C 1-3 alkyl; for example, R 1 is selected from H or methyl.
  • R 2 is Hydroxyl in In the linking group formed after the reaction of R 3 ', in essence, R 2 is the residue of R 3 ', wherein R 3 ' is the end-capping group of M.
  • R 3 and R 3 ' are the same or different, independently selected from H, OH, COOH, NH 2 and other end-capping groups that can react with hydroxyl groups, and cannot be H at the same time.
  • the polyphenylene ether segment has a repeating unit shown in formula 2:
  • R 4 is selected from H or C 1-6 alkyl, and m is an integer between 0-4.
  • R 4 is selected from H or C 1-3 alkyl, and m is an integer between 0 and 2; specifically, the polyphenylene ether segment has a repeating unit represented by formula 2':
  • the polyethylene glycol segment has a repeating unit shown in formula 3:
  • the polypropylene glycol segment has a repeating unit shown in formula 4:
  • the polyethylene dithiol segment has a repeating unit shown in formula 5:
  • the polycarbonate segment has a repeating unit represented by formula 6:
  • the polysiloxane segment has repeating units represented by formula 7:
  • the number average molecular weight of M is 200-40000.
  • the polymer is selected from polyphenylene ether polyacrylate, polyethylene glycol polymethyl methacrylate, polyethylene dithiol polymethyl methacrylate, polycarbonate polyacrylate , at least one of polypropylene glycol polymethacrylate and polysilicon ether polymethyl methacrylate.
  • the number average molecular weight of the polymer is 10,000-300,000, preferably 10,000-200,000.
  • the monomer for preparing the polymer is selected from the compounds shown in the following formula 8:
  • R 1 , R 2 , R 3 , and M are defined as described above.
  • the compound represented by the formula 8 is selected from polyphenylene ether acrylate, polyethylene glycol methyl methacrylate, polycarbonate acrylate, polypropylene glycol methacrylate, lithium polysulfonate At least one of methacrylate and polysilyl ether methyl methacrylate.
  • the positive electrode active material layer comprises the following components by mass percentage: 70-95 wt % of the positive active material, 2-15 wt % of the conductive agent, 3-28 wt % of the above-mentioned polymer Electrolyte, 0-10 wt% binder.
  • the molar ratio of other elements in the polymer except carbon and hydrogen to lithium in the lithium salt is 5:1-25:1, such as 5:1 , 10:1, 15:1, 20:1, 25:1, wherein the other elements other than carbon and hydrogen can be, for example, oxygen, sulfur or silicon.
  • the mass percentage of the positive active material is 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt%, 80wt%, 81wt% , 82wt%, 83wt%, 84wt%, 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%.
  • the mass percentage content of the conductive agent is 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%.
  • the mass percentage of the polymer electrolyte is 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt% , 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%.
  • the mass percentage of the binder is 0wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%.
  • the positive active material is selected from lithium iron phosphate (LiFePO 4 ), lithium cobalt oxide (LiCoO 2 ), lithium nickel cobalt manganese oxide (L z Ni x Co y Mn 1-xy O 2 , Wherein 0.95 ⁇ z ⁇ 1.05, x>0, y>0, 0 ⁇ x+y ⁇ 1), lithium manganate (LiMnO 2 ), lithium nickel cobalt aluminate (Li z Ni x Co y Al 1-xy O 2 , where 0.95 ⁇ z ⁇ 1.05, x>0, y>0, 0.8 ⁇ x+y ⁇ 1), lithium nickel cobalt manganese aluminate (Li z Ni x Co y Mn w Al 1-xyw O 2 , where 0.95 ⁇ z ⁇ 1.05, x>0, y>0, w>0, 0.8 ⁇ x+y+w ⁇ 1), nickel-cobalt-aluminum-tungsten material, lithium
  • the lithium salt is selected from lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium tetrafluoroborate (LiBF 4 ), bis-oxalic acid Lithium Borate (LiBOB), Lithium Difluoroborate Oxalate (LiDFOB), Lithium Bisdifluorosulfonimide (LiFSI), Lithium Bistrifluoromethanesulfonimide (LiTFSI), Lithium Trifluoromethanesulfonate (LiCF) 3 SO 3 ), bismalonate boric acid (LiBMB), lithium malonate oxalate borate (LiMOB), lithium hexafluoroantimonate (LiSbF 6 ), lithium difluorophosphate (LiPF 2 O 2 ), 4,5-diflu
  • the conductive agent is selected from conductive carbon black, ketjen black, conductive fibers, conductive polymers, acetylene black, carbon nanotubes, graphene, flake graphite, conductive oxides, and metal particles. one or more.
  • the binder is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexafluoropropylene, and polylithium polyacrylate (PAALi). kind.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PAALi polylithium polyacrylate
  • the positive electrode sheet is used in a solid-state battery (eg, an all-solid-state battery).
  • the porosity of the positive electrode sheet is 0%-5%.
  • the elongation and elongation ratio of the positive electrode active material layer in the positive electrode sheet is 5% to 500%.
  • the areal density of the positive electrode sheet is 5-30 mg/cm 2 .
  • the present invention also provides a method for preparing the above-mentioned positive electrode sheet, the method comprising the following steps: uniformly mixing a solvent, a positive electrode active material, a conductive agent, a polymer monomer shown in formula 8, an initiator, and a lithium salt to prepare a positive electrode Slurry; coating the positive electrode slurry on the surface of the positive electrode current collector, drying and hot pressing to prepare the positive electrode sheet.
  • the positive electrode slurry contains 200-1000 parts of solvent, 70-95 parts of positive electrode active material, 2-15 parts of conductive agent, and 3-28 parts of polymer monomer represented by formula 8 , an initiator and a lithium salt, and 0-10 parts of a binder; wherein, the molar ratio of other elements other than carbon and hydrogen in the polymer monomer shown in the formula 8 to the lithium element in the lithium salt is 5:1 -25:1, the added amount of the initiator is 0.05-1 wt% of the mass of the polymer monomer shown in formula 8.
  • the initiator may be azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tertiary benzoyl peroxide One or more of butyl ester, 4-(N,N-dimethylamino) ethyl benzoate, methyl o-benzoyl benzoate, etc.
  • the solvent is selected from at least one of N-methylpyrrolidone, acetonitrile, hydrofluoroether, acetone, tetrahydrofuran, dichloromethane, pyridine, etc., xylene, and toluene.
  • the positive electrode slurry is preferably a sieved positive electrode slurry, for example, passed through a 200-mesh sieve.
  • the temperature of the drying treatment is 60°C-120°C, and the drying treatment time is 6-36 hours; also preferably, the drying is performed under vacuum conditions.
  • the temperature of the hot-pressing treatment is 50°C-90°C, and the time of the hot-pressing treatment is 5-60 minutes.
  • the positive electrode active material, conductive agent, optional binder, polymer monomer, initiator and lithium salt are dissolved in a solvent, and after uniform mixing, coating is carried out on the surface of the current collector. After drying, hot pressing the pole piece to obtain the positive pole piece of the present invention.
  • the polymer monomer can be fully mixed with the positive electrode active material, conductive agent, optional binder and lithium salt due to its small molecular weight and short polymer segments.
  • a high-efficiency lithium-conducting and conductive network has been formed, and vacuum hot pressing is performed on it.
  • hot pressing is to initiate thermal polymerization of polymer monomers.
  • the polymer monomers are viscous liquid, semi-solid or solid at room temperature.
  • the polymer monomer becomes a flowable liquid, which can be fully immersed in the internal voids of the pole pieces, and thermally-initiated polymerization is carried out in the voids.
  • the thermal polymerization process time, temperature
  • the vacuum can remove the air between the particles inside the pole piece, and the hot pressing can ensure the compaction of the pole piece, which is closer to the practical application.
  • the above process is mainly to ensure low porosity, High-efficiency lithium-conducting, high-efficiency conductive pole piece performance.
  • the present invention also provides a solid-state battery, the solid-state battery includes the above-mentioned positive electrode plate.
  • the present invention also provides an electrical device comprising the above-mentioned positive electrode piece.
  • the electrical device is a digital electrical appliance, a power tool, an energy storage period, an unmanned aerial vehicle, a household appliance, an energy storage product, an electric vehicle, a power tool, and the like.
  • 92g positive electrode active material lithium cobaltate, 3g polyphenylene ether acrylate, 0.33g LiBF 4 , 0.67g LiTFSI, 1g binder polyvinylidene fluoride (PVDF), 1g conductive agent conductive carbon black, 1g conductive agent carbon nanotube , 0.01g of azobisisobutyronitrile were mixed, 1000g of N-methylpyrrolidone (NMP) was added, and stirred under the action of a vacuum mixer until the mixed system became a uniform fluid positive electrode slurry; the positive electrode slurry was evenly coated on the thickness of It is placed on 10 ⁇ m aluminum foil; after drying at 60°C for 36 hours, a pole piece is obtained after vacuum treatment, and the pole piece is hot-pressed at 50°C for 60 minutes, and then cut to obtain a positive pole piece;
  • NMP N-methylpyrrolidone
  • a solid lithium ion battery cell is prepared by laminating the above-obtained positive pole piece, solid electrolyte membrane, and negative pole piece, and after welding and packaging, a lithium ion battery is obtained.
  • Example 1 The specific process refers to Example 1, the main difference is that in Comparative Example 1-1, polyphenylene ether is used instead of polyphenylene ether acrylate in Example 1, and other conditions are consistent with Example 1.
  • Example 1 The specific process refers to Example 1, and the main difference is that in Comparative Examples 1-2, a mixture of polyphenylene ether and polyacrylate of the same quality as the polyphenylene ether acrylate monomer is used to replace the polyphenylene ether acrylate in Example 1, wherein the polyphenylene ether acrylate is The mass ratio of phenylene ether and polyacrylate is the molecular weight ratio of polyphenylene ether and acrylate in the polyphenylene ether acrylate monomer, and other conditions are the same as those in Example 1.
  • Example 1 The specific process refers to Example 1, and the main difference is the process conditions, the amount of each component added, and the type of each component material.
  • Table 1 and Table 2 The specific details are shown in Table 1 and Table 2.
  • Examples 1-6 in Table 1 further contain 0.01g
  • the initiators are all azobisisobutyronitrile.
  • the addition amount of two kinds of polymers is the ratio of the molecular weight of polymer segment and poly(meth)acrylate in the polymerized monomer added in the corresponding embodiment, specifically See the description in Comparative Examples 1-2 above.
  • Battery internal resistance AC impedance test method Use Metrohm PGSTAT302N chemical workstation in the range of 100KHz-0.1mHz and under the condition of 60 °C to perform AC impedance test on lithium-ion batteries.
  • Porosity test method of the pole piece use AutoPore V series 9610 mercury porosimeter to test the porosity of the pole piece, take a certain pole piece and place it in the dilatometer, apply high pressure sealing oil, seal it with thread after capping, and place it in the dilatometer. The porosity of the pole piece under high pressure is tested under high pressure in a high pressure system.
  • Test method of pole piece extension pulling rate Coat the positive electrode slurry on a smooth and flat surface, after drying and hot pressing, a paste layer is obtained, which is prepared into a 60mm*20mm*1mm (length*width*thickness) sample. Tensile tests were performed on the universal material testing machine GH-969C.
  • Battery cycle performance test method Li-ion battery is charged and discharged on the blue battery charge and discharge test cabinet.
  • the test conditions are 60°C, 0.3C/0.3C charge and discharge, and the number of cycles when the battery capacity retention rate is reduced to 80% is investigated. .
  • Battery cycle rate performance test method Li-ion battery is charged and discharged on the blue battery charge-discharge test cabinet.
  • the test condition is 60°C, 0.3C/0.3C (5 cycles) ⁇ 0.5C/0.5C (5 cycles) cycle) ⁇ 1C/1C (5 cycles) ⁇ 2C/2C (5 cycles) ⁇ 0.3C/0.3C (5 cycles) process.
  • Example 1 2 30 120 Comparative Example 1-1 30 10 560 Comparative Example 1-2 27 5 930 Example 2 1 450 113 Comparative Example 2-1 27 200 530 Comparative Example 2-2 25 80 895 Example 3 4 260 128 Comparative Example 3-1 26 240 630 Comparative Example 3-2 25 50 937 Example 4 0.5 50 103 Comparative Example 4-1 25 twenty three 421 Comparative Example 4-2 29 6 774 Example 5 4.5 200 146 Comparative Example 5-1 twenty three 120 621 Comparative Example 5-2 twenty one 70 1062 Example 6 0.8 230 153 Comparative Example 6-1 twenty four 140 624 Comparative Example 6-2 26 90 1085
  • the porosity test results show that: in the example, the compound represented by formula 8 is used to prepare the positive electrode sheet, which has a low porosity; in the comparative example, the low porosity effect cannot be achieved by using the molding polymer.
  • the main reason is that the compound represented by formula 8 is used as the polymer monomer in the present invention, which is liquid under heating conditions, can fully contact the particles, enter between the pores, and realize in-situ polymerization between the pores, that is, the low Porosity positive pole piece.
  • the results of the elongation elongation test show that the elongation elongation ratio of the positive electrode active material layer in Examples 1-6 is related to the addition amount of the polymer monomer.
  • the battery internal resistance test results show that: the compound shown in formula 8 in the embodiment of the present invention can effectively bond the particles in the positive electrode plate, and the polymer has a comb-like structure, and the branched chain can conduct lithium conduction, so the embodiment
  • the positive electrodes prepared in 1-6 have low internal resistance.
  • the positive electrode sheet prepared in the comparative example has a higher internal resistance.
  • the test results of the cycle performance of the examples and the comparative examples show that: the positive electrode sheet of the present invention has low porosity and low internal resistance, which makes the prepared battery have advantages in cycle performance; The resistance is large, resulting in a significant reduction in the effective cycle times of the prepared battery.
  • test results of the rate charge and discharge performance of the examples and comparative examples show that the positive electrode sheet of the present invention has low porosity and low internal resistance, and lithium ions have good lithium-conducting conduction channels inside the positive electrode sheet, so that the prepared lithium ion battery It has good rate performance and good application value.

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Abstract

一种正极极片及含该正极极片的二次电池。通过选用一类与现有技术不同的聚合物制备的聚合物电解质作为正极极片中的固态电解质，所述固态电解质既具有粘结功能又具有导锂功能，可以替代现有的极片中的粘结剂和固态电解质，能够有效改善并提升锂离子的传输性能，降低电池的内阻。同时，含有该固态电解质的正极极片的孔隙率低，约为5％以下，这大大降低了正极极片内部的空隙和孔洞，提升单位体积内的正极活性物质的含量，改善锂离子和电子的传输，有效提升电池的能量密度、循环性能和倍率性能，含有该固态电解质的正极极片可应用于高能量密度电池体系，扩宽了其应用领域。

Description

一种正极极片及含该正极极片的二次电池 技术领域
本发明涉及二次电池技术领域，尤其涉及一种正极极片及含该正极极片的二次电池。
背景技术
锂离子电池具有循环寿命长、能量密度高、绿色环保等优点，目前已经应用于储能领域、动力领域、数码领域。随着市场对高能量密度电池的迫切需求，传统锂离子电池体系日益难以满足市场需求。锂离子电池主要由正极、负极、隔膜、电解液构成，电解液主要由有机溶剂构成，在高能量密度电池体系中电池存在漏液、起火、爆炸等安全问题。固态电池有希望能从根本上改善锂离子电池安全性能，目前已经得到国内外广泛关注。
固态电池是下一代高能量密度储能电池的有力竞争者。但是全固态电解质还面临着界面接触阻抗过大的问题，特别是在正极一侧，大大制约了全固态电解质的应用。固态电解质目前主要有硫化物电解质、氧化物电解质、聚合物电解质、氢化物电解质等，其中硫化物电解质存在界面阻抗高、性能不稳定等缺点；氧化物电解质存在电导率低、界面接触差等缺点；氢化物电解质存在性能不稳定、易燃易爆等缺点；而聚合物电解质具有加工性能好、室温电导率低等特点。
同时，固态电池的正极中还存在界面接触差、孔隙率高、聚合物电解质氧化分解等问题，直接影响固态电池的循环性能。
发明内容
为了改善现有技术的不足，本发明的目的是提供一种正极极片及含正极该片的二次电池。
研究发现，常规全固态电池的正极极片中主要含有正极活性物质、导电剂、粘结剂和固态电解质，通过将所述正极活性物质、导电剂、粘结剂和固态电解质均匀混合后，涂布在集流体表面上，经烘干、裁切处理后得到固态电池用正 极极片，并将正极极片、固态电解质、负极极片进行叠片，得到固态锂离子电池。常规全固态电池在充放电过程中会存在极片和固态电解质之间的界面接触差、极片表面的孔隙率高等问题，这大大影响了固态电池的循环性能。
本发明目的是通过如下技术方案实现的：
一种正极极片，所述正极极片包括正极集流体和涂覆在正极集流体一侧或两侧表面的正极活性物质层，所述正极活性物质层包括正极活性物质、导电剂和聚合物电解质，其中，所述聚合物电解质包括聚合物和锂盐，所述聚合物包括如下式1所示的重复单元：
Figure PCTCN2021094181-appb-000001
式1中，R 1选自H或C 1-6烷基；R 2选自连接基团；R 3选自封端基团；M选自聚苯醚链段、聚乙二醇链段、聚乙二硫醇链段、聚碳酸酯链段、聚丙二醇链段或聚硅醚链段。
根据本发明，R 1选自H或C 1-3烷基；R 2为
Figure PCTCN2021094181-appb-000002
中的羟基与
Figure PCTCN2021094181-appb-000003
中的R 3’反应之后形成的连接基团；R 3和R 3’相同或不同，彼此独立地选自H、OH、COOH、NH 2，且不能同时为H。
根据本发明，所述聚苯醚链段具有式2所示重复单元：
Figure PCTCN2021094181-appb-000004
式2中，R 4选自H或C 1-6烷基，m为0-4之间的整数。示例性地，R 4选自H或C 1-3烷基，m为0-2之间的整数；
所述聚乙二醇链段具有式3所示重复单元：
Figure PCTCN2021094181-appb-000005
所述聚丙二醇链段具有式4所示重复单元：
Figure PCTCN2021094181-appb-000006
所述聚乙二硫醇链段具有式5所示重复单元：
Figure PCTCN2021094181-appb-000007
所述聚碳酸酯链段具有式6所示重复单元：
Figure PCTCN2021094181-appb-000008
所述聚硅醚链段具有式7所示重复单元：
Figure PCTCN2021094181-appb-000009
根据本发明，所述聚合物选自聚苯醚聚丙烯酸酯、聚乙二醇聚甲基丙烯酸甲酯、聚乙二硫醇聚甲基丙烯酸甲酯、聚碳酸酯聚丙烯酸酯、聚丙二醇聚甲基丙烯酸酯、聚硅醚聚甲基丙烯酸甲酯中的至少一种。
根据本发明，制备所述聚合物的单体选自如下式8所示化合物：
Figure PCTCN2021094181-appb-000010
式8中，R 1、R 2、R 3、M的定义如上所述。
根据本发明，所述式8所示化合物选自聚苯醚丙烯酸酯、聚乙二醇甲基丙烯酸甲酯、聚碳酸酯丙烯酸酯、聚丙二醇甲基丙烯酸酯、聚磺酸锂甲基丙烯酸酯、聚硅醚甲基丙烯酸甲酯中的至少一种。
根据本发明，所述正极活性物质层包括如下质量百分含量的各组分：70-95wt％的正极活性物质、2-15wt％的导电剂、3-28wt％的上述聚合物电解质、0-10wt％粘结剂。
根据本发明，所述聚合物电解质中，所述聚合物中除碳、氢以外的其他元素与锂盐中锂元素的摩尔比为5:1-25:1，如5:1、10:1、15:1、20:1、25:1，其中，所述除碳、氢以外的其他元素例如可以是氧元素、硫元素或硅元素。
根据本发明，所述正极极片的孔隙率为0％-5％；和/或所述正极极片中的正极活性物质层的延长拉伸率为5％-500％。
本发明还提供一种固态电池，所述固态电池包括上述的正极极片。
本发明的有益效果：
本发明提供了一种正极极片及含该正极极片的二次电池。本发明通过选用一类与现有技术不同的聚合物制备的聚合物电解质作为正极极片中的固态电解质，所述固态电解质既具有粘结功能又具有导锂功能，可以替代现有的极片中的粘结剂和固态电解质，能够有效改善并提升锂离子的传输性能，降低电池的内阻。同时，含有该固态电解质的正极极片的孔隙率低，约为5％以下，这大大降低了正极极片内部的空隙和孔洞，提升单位体积内的正极活性物质的含量，改善锂离子和电子的传输，有效提升电池的能量密度、循环性能和倍率性能，含有该固态电解质的正极极片可应用于高能量密度电池体系，扩宽了其应用领域。
具体实施方式
<正极极片>
如前所述，本发明提供一种正极极片，所述正极极片包括正极集流体和涂覆在正极集流体一侧或两侧表面的正极活性物质层，所述正极活性物质层包括 正极活性物质、导电剂和聚合物电解质，其中，所述聚合物电解质包括聚合物和锂盐，所述聚合物包括如下式1所示的重复单元：
Figure PCTCN2021094181-appb-000011
式1中，R 1选自H或C 1-6烷基；R 2选自连接基团；R 3选自封端基团；M选自聚苯醚链段、聚乙二醇链段、聚乙二硫醇链段、聚碳酸酯链段、聚丙二醇链段或聚硅醚链段。
在本发明的一个方案中，R 1选自H或C 1-3烷基；如R 1选自H或甲基。
在本发明的一个方案中，R 2为
Figure PCTCN2021094181-appb-000012
中的羟基与
Figure PCTCN2021094181-appb-000013
中的R 3’反应之后形成的连接基团，实质上，R 2为R 3’的残基，其中，R 3’为M的封端基团。
在本发明的一个方案中，R 3和R 3’相同或不同，彼此独立地选自H、OH、COOH、NH 2等可以和羟基发生反应的封端基团，且不能同时为H。
在本发明的一个方案中，所述聚苯醚链段具有式2所示重复单元：
Figure PCTCN2021094181-appb-000014
式2中，R 4选自H或C 1-6烷基，m为0-4之间的整数。示例性地，R 4选自H或C 1-3烷基，m为0-2之间的整数；具体的，所述聚苯醚链段具有式2’所示重复单元：
Figure PCTCN2021094181-appb-000015
在本发明的一个方案中，所述聚乙二醇链段具有式3所示重复单元：
Figure PCTCN2021094181-appb-000016
在本发明的一个方案中，所述聚丙二醇链段具有式4所示重复单元：
Figure PCTCN2021094181-appb-000017
在本发明的一个方案中，所述聚乙二硫醇链段具有式5所示重复单元：
Figure PCTCN2021094181-appb-000018
在本发明的一个方案中，所述聚碳酸酯链段具有式6所示重复单元：
Figure PCTCN2021094181-appb-000019
在本发明的一个方案中，所述聚硅醚链段具有式7所示重复单元：
Figure PCTCN2021094181-appb-000020
在本发明的一个方案中，所述M的数均分子量为200-40000。
在本发明的一个方案中，所述聚合物选自聚苯醚聚丙烯酸酯、聚乙二醇聚甲基丙烯酸甲酯、聚乙二硫醇聚甲基丙烯酸甲酯、聚碳酸酯聚丙烯酸酯、聚丙二醇聚甲基丙烯酸酯、聚硅醚聚甲基丙烯酸甲酯中的至少一种。
在本发明的一个方案中，所述聚合物的数均分子量为0.1万-30万，优选1万-20万。
在本发明的一个方案中，制备所述聚合物的单体选自如下式8所示化合物：
Figure PCTCN2021094181-appb-000021
式8中，R 1、R 2、R 3、M的定义如上所述。
在本发明的一个方案中，所述式8所示化合物选自聚苯醚丙烯酸酯、聚乙二醇甲基丙烯酸甲酯、聚碳酸酯丙烯酸酯、聚丙二醇甲基丙烯酸酯、聚磺酸锂甲基丙烯酸酯、聚硅醚甲基丙烯酸甲酯中的至少一种。
在本发明的一个方案中，所述正极活性物质层包括如下质量百分含量的各组分：70-95wt％的正极活性物质、2-15wt％的导电剂、3-28wt％的上述聚合物电解质、0-10wt％粘结剂。
在本发明的一个方案中，所述聚合物电解质中，所述聚合物中除碳、氢以外的其他元素与锂盐中锂元素的摩尔比为5:1-25:1，如5:1、10:1、15:1、20:1、25:1，其中，所述除碳、氢以外的其他元素例如可以是氧元素、硫元素或硅元素。
示例性地，所述正极活性物质的质量百分含量为70wt％、71wt％、72wt％、73wt％、74wt％、75wt％、76wt％、77wt％、78wt％、79wt％、80wt％、81wt％、82wt％、83wt％、84wt％、85wt％、86wt％、87wt％、88wt％、89wt％、90wt％、91wt％、92wt％、93wt％、94wt％、95wt％。
示例性地，所述导电剂的质量百分含量为2wt％、3wt％、4wt％、5wt％、6wt％、7wt％、8wt％、9wt％、10wt％、11wt％、12wt％、13wt％、14wt％、15wt％。
示例性地，所述聚合物电解质的质量百分含量为2wt％、3wt％、4wt％、5wt％、6wt％、7wt％、8wt％、9wt％、10wt％、11wt％、12wt％、13wt％、14wt％、15wt％、16wt％、17wt％、18wt％、19wt％、20wt％、21wt％、22wt％、23wt％、24wt％、25wt％、26wt％、27wt％、28wt％。
示例性地，所述粘结剂的质量百分含量为0wt％、1wt％、2wt％、3wt％、4wt％、5wt％、6wt％、7wt％、8wt％、9wt％、10wt％。
在本发明的一个方案中，所述正极活性物质选自磷酸铁锂(LiFePO 4)、钴酸锂(LiCoO 2)、镍钴锰酸锂(Li zNi xCo yMn 1-x-yO 2，其中0.95≤z≤1.05，x>0，y>0，0<x+y<1)、锰酸锂(LiMnO 2)、镍钴铝酸锂(Li zNi xCo yAl 1-x-yO 2，其中0.95≤z≤1.05，x>0，y>0，0.8≤x+y<1)、镍钴锰铝酸锂(Li zNi xCo yMn wAl 1-x-y-wO 2，其中0.95≤z≤1.05，x>0，y>0，w>0，0.8≤x+y+w<1)、镍钴铝钨材料、富锂锰基固溶体正极材料(xLi 2MnO 3·(1-x)LiMO 2，其中M＝Ni/Co/Mn)、镍钴酸锂(LiNi xCo yO 2，其中x>0，y>0，x+y＝1)、镍钛镁酸锂(LiNi xTi yMg zO 2，其中，x>0，y>0，z>0，x+y+z＝1)、镍酸锂(Li 2NiO 2)、尖晶石锰酸锂(LiMn 2O 4)、镍钴钨材料中的一种或几种的组合。
在本发明的一个方案中，所述锂盐选自高氯酸锂(LiClO 4)、六氟磷酸锂(LiPF 6)、六氟砷酸锂(LiAsF 6)、四氟硼酸锂(LiBF 4)、双草酸硼酸锂(LiBOB)、草酸二氟硼酸锂(LiDFOB)、双二氟磺酰亚胺锂(LiFSI)、双三氟甲基磺酰亚胺锂(LiTFSI)、三氟甲基磺酸锂(LiCF 3SO 3)、双丙二酸硼酸(LiBMB)、丙二酸草酸硼酸锂(LiMOB)、六氟锑酸锂(LiSbF 6)、二氟磷酸锂(LiPF 2O 2)、4,5-二氰基-2-三氟甲基咪唑锂(LiDTI)、二(三氟甲基磺酰)亚胺锂(LiN(SO 2CF 3) 2)、LiN(SO 2C 2F 5) 2、LiC(SO 2CF 3) 3、LiN(SO 2F) 2的一种或任意组合。
在本发明的一个方案中，所述导电剂选自导电炭黑、科琴黑、导电纤维、导电聚合物、乙炔黑、碳纳米管、石墨烯、鳞片石墨、导电氧化物、金属颗粒中的一种或几种。
在本发明的一个方案中，所述粘结剂选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚偏氟乙烯-六氟丙烯、聚丙烯酸锂(PAALi)中的至少一种。
在本发明的一个方案中，所述正极极片用于固态电池(如全固态电池)中。
在本发明的一个方案中，所述正极极片的孔隙率为0％-5％。
在本发明的一个方案中，所述正极极片中的正极活性物质层的延长拉伸率为5％-500％。
在本发明的一个方案中，所述正极极片的面密度为5-30mg/cm 2。
本发明还提供上述正极极片的制备方法，所述方法包括如下步骤：将溶剂、正极活性物质、导电剂、式8所示的聚合物单体、引发剂、锂盐均匀混合，制备得到正极浆料；将正极浆料涂布在正极集流体表面，经过干燥和热压处理，制备得到所述正极极片。
在本发明的一个方案中，所述正极浆料中含有200-1000份溶剂、70-95份正极活性物质、2-15份导电剂、3-28份的式8所示的聚合物单体、引发剂和锂盐、0-10份粘结剂；其中，所述式8所示的聚合物单体中除碳、氢以外的其他元素与锂盐中锂元素的摩尔比为5:1-25:1，所述引发剂的加入量为式8所示的聚合物单体质量的0.05-1wt％。
在本发明的一个方案中，所述引发剂可以为偶氮二异丁腈、偶氮二异庚腈、偶氮二异丁酸二甲酯、过氧化苯甲酰、过氧化苯甲酰叔丁酯、4-(N,N-二甲氨基)苯甲酸乙酯、邻苯甲酰苯甲酸甲酯等中的一种或几种。
在本发明的一个方案中，所述溶剂选自N-甲基吡咯烷酮、乙腈、氢氟醚、丙酮、四氢呋喃、二氯甲烷、吡啶等、二甲苯、甲苯中的至少一种。
在本发明的一个方案中，所述正极浆料优选过筛后的正极浆料，例如过200目的筛子。
在本发明的一个方案中，所述干燥处理的温度为60℃-120℃，所述干燥处理的时间为6-36小时；还优选地，所述干燥是在真空条件下进行的。
在本发明的一个方案中，所述热压处理的温度为50℃-90℃，所述热压处理的时间为5-60分钟。
研究发现，本发明中，将正极活性物质、导电剂、任选地粘结剂、聚合物单体、引发剂和锂盐溶于溶剂中，均匀混合后，在集流体表面进行涂布，经过烘干后，对该极片进行热压，即可得到本发明的正极极片。
在正极浆料中，聚合物单体由于分子量小、聚合物链段短，能够与正极活性物质、导电剂、任选地粘结剂和锂盐充分混合，除去溶剂后，正极活性物质层内部已经形成高效导锂导电的网络，对其进行真空热压，一方面热压是为了引发聚合物单体进行热聚合，聚合物单体常温下为粘稠液态、半固态或固态，在高温下聚合物单体变成可流动的液态，可以充分浸入极片内部空隙中，在空隙中进行热引发聚合，其中热聚合工艺(时间、温度)是可以调控的，保证正极极片的导锂导电性能；另一方面，采用真空热压聚合物工艺，真空能够除去极片内部颗粒之间的空气，热压能够保证极片的压实，更贴近实际应用，以上工艺主要是保证低空隙率、高效导锂、高效导电的极片性能。
本发明还提供一种固态电池，所述固态电池包括上述的正极极片。
本发明还提供一种电学器件，所述电学器件包括上述的正极极片。
在本发明的一个方案中，所述电学器件为数码电器、动力工具、储能期间、无人机、家用电器、储能产品、电动汽车、电动工具等。
下文将结合具体实施例对本发明做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本发明，而不应被解释为对本发明保护范围的限制。凡基于本发明上述内容所实现的技术均涵盖在本发明旨在保护的范围内。
下述实施例中所使用的实验方法如无特殊说明，均为常规方法；下述实施例中所用的试剂、材料等，如无特殊说明，均可从商业途径得到。
实施例1
1)正极极片的制备：
将92g正极活性物质钴酸锂、3g聚苯醚丙烯酸酯、0.33g LiBF 4、0.67g LiTFSI、1g粘结剂聚偏氟乙烯(PVDF)、1g导电剂导电炭黑、1g导电剂碳纳米管、0.01g偶氮二异丁腈进行混合，加入1000gN-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌，直至混合体系成均一流动性的正极浆料；将正极浆料均匀涂覆于厚度为10μm的铝箔上；经过烘干60℃处理36小时后，抽真空处理后得到极片，并将该极片进行热压50℃处理60分钟后，裁切得到正极极片；
2)负极极片制备：
将5g氧化亚硅、10g锂金属粉末、3g导电剂导电炭黑、1g粘结剂油系丙烯酸酯，溶解在50g二甲苯中，均匀混合后，涂覆于负极集流体铜箔的表面，经烘干(温度：85℃，时间：5h、氩气气体)、辊压和模切得到负极极片；
3)固态电解质膜的制备：
将100g聚氧化乙烯、20g LiTFSI、1000g乙腈一起加入反应器中，以500r/min的速度搅拌，在惰性气体保护下搅拌24h，将浆料涂布在平整聚四氟乙烯板面，除去溶剂得到固态电解质膜；
4)锂离子电池的制备
将上述得到的正极极片、固态电解质膜、负极极片通过叠片方式制备固态锂离子电池电芯，经过焊接封装后，得到锂离子电池。
对比例1-1
具体工艺参考实施例1，主要区别对比例1-1中采用聚苯醚替代实施例1中聚苯醚丙烯酸酯，其他条件与实施例1一致。
对比例1-2
具体工艺参考实施例1，主要区别对比例1-2中采用与聚苯醚丙烯酸酯单体等质量的聚苯醚和聚丙烯酸酯的混合物替代实施例1中的聚苯醚丙烯酸酯，其中聚苯醚和聚丙烯酸酯的质量比为聚苯醚丙烯酸酯单体中聚苯醚和丙烯酸酯的分子量比，其他条件与实施例1一致。
其他实施例和其他对比例
具体流程参考实施例1，主要区别是工艺条件、各组分加入量、各组分物料种类，具体详情见表1和表2，其中，表1中的实施例1-6中进一步含有0.01g的引发剂，所述引发剂均为偶氮二异丁腈。表2中的添加两种聚合物的对比例中，两种聚合物的加入量为对应实施例中加入的聚合单体中聚合物链段和聚(甲基)丙烯酸酯的分子量的比，具体参见上述对比例1-2中的说明。
表1
Figure PCTCN2021094181-appb-000022
表2
Figure PCTCN2021094181-appb-000023
Figure PCTCN2021094181-appb-000024
性能测试：
电池内阻交流阻抗测试方法：采用Metrohm瑞士万通PGSTAT302N化学工作站在100KHz-0.1mHz范围，60℃条件下，对锂离子电池进行交流阻抗测试。
极片孔隙率测试方法：采用AutoPore V系列9610型号压汞仪对极片的孔隙率进行测试，取一定极片置于膨胀计中，涂高压密封油后，加盖后用螺纹密封，置于高压系统中加压测试高压下极片的孔隙率。
极片延长拉升率测试方法：将正极浆料涂布在光滑平整表面，经过烘干热压后，得到涂膏层，制备成60mm*20mm*1mm(长*宽*厚)样品，在液压万能材料试验机GH-969C型上进行拉伸测试。
电池循环性能测试方法：锂离子电池在蓝电电池充放电测试柜上进行充放电循环测试，测试条件为60℃、0.3C/0.3C充放电，考察电池容量保持率降为80％时的循环次数。
电池循环倍率性能测试方法：锂离子电池在蓝电电池充放电测试柜上进行充放电循环测试，测试条件为60℃，进行0.3C/0.3C(5次循环)→0.5C/0.5C(5 次循环)→1C/1C(5次循环)→2C/2C(5次循环)→0.3C/0.3C(5次循环)流程。
表3 实施例和对比例的电池内阻、正极极片的孔隙率、正极活性物质层的延长拉伸率
序号 孔隙率(％) 延长拉伸率(％) 电池内阻(mΩ)
实施例1 2 30 120
对比例1-1 30 10 560
对比例1-2 27 5 930
实施例2 1 450 113
对比例2-1 27 200 530
对比例2-2 25 80 895
实施例3 4 260 128
对比例3-1 26 240 630
对比例3-2 25 50 937
实施例4 0.5 50 103
对比例4-1 25 23 421
对比例4-2 29 6 774
实施例5 4.5 200 146
对比例5-1 23 120 621
对比例5-2 21 70 1062
实施例6 0.8 230 153
对比例6-1 24 140 624
对比例6-2 26 90 1085
孔隙率测试结果表明：实施例中采用式8所示化合物制备正极极片，具有较低的孔隙率；对比例中，采用成型聚合物达不到低空隙率效果。主要原因是本发明中采用式8所示化合物为聚合物单体，其在加热条件下为液态，能够充分与颗粒接触，进入空隙之间，在孔隙之间实现原位聚合，即制备得到低孔隙率的正极极片。
延长拉伸率测试结果表明：通过实施例1-6的正极活性物质层的延长拉伸率对比可以看出，正极活性物质层的延长拉伸率与聚合物单体的加入量有关，聚合物单体的加入量越多，延长拉伸率越好；通过实施例和对比例相比，本发明的式8所示化合物具有明显的梳状聚合物功能，主链为碳碳键，支链具有梳状，能够有效结合正极极片中的颗粒物质，具有良好的高弹状态，具有良好的延长 拉伸率。
电池内阻测试结果表明：本发明实施例采用式8所示化合物能够有效的将正极极片中的颗粒进行粘结，同时该聚合物具有梳状结构，支链可以进行导锂，所以实施例1-6制备的正极极片内阻低。而对比例中存在较高的孔隙率且聚丙烯酸酯不导锂，所以对比例制备的正极极片内阻较高。
表4 实施例和对比例的电池循环性能和倍率性能
Figure PCTCN2021094181-appb-000025
实施例和对比例循环性能测试结果表明：本发明的正极极片的孔隙率低且内阻小，使得制备得到的电池的循环性能具有优势；而对比例的正极极片孔隙率大、电池内阻大，导致制备得到的电池的有效循环次数大幅降低。
实施例和对比例倍率充放电性能测试结果表明：本发明的正极极片的孔隙率低且内阻小，锂离子在正极极片内部存在良好的导锂导电通道，使得制备得到的锂离子电池具有良好的倍率性能，具有良好的应用价值。
以上，对本发明的实施方式进行了说明。但是，本发明不限定于上述实施方式。凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种正极极片，其中，所述正极极片包括正极集流体和涂覆在正极集流体一侧或两侧表面的正极活性物质层，所述正极活性物质层包括正极活性物质、导电剂和聚合物电解质，其中，所述聚合物电解质包括聚合物和锂盐，所述聚合物包括如下式1所示的重复单元：
    Figure PCTCN2021094181-appb-100001
    式1中，R 1选自H或C 1-6烷基；R 2选自连接基团；R 3选自封端基团；M选自聚苯醚链段、聚乙二醇链段、聚乙二硫醇链段、聚碳酸酯链段、聚丙二醇链段或聚硅醚链段。
  2. 根据权利要求1所述的正极极片，其中，R 1选自H或C 1-3烷基；R 2为
    Figure PCTCN2021094181-appb-100002
    中的羟基与
    Figure PCTCN2021094181-appb-100003
    中的R 3’反应之后形成的连接基团；R 3和R 3’相同或不同，彼此独立地选自H、OH、COOH、NH 2，且不能同时为H。
  3. 根据权利要求1或2所述的正极极片，其中，所述聚苯醚链段具有式2所示重复单元：
    Figure PCTCN2021094181-appb-100004
    式2中，R 4选自H或C 1-6烷基，m为0-4之间的整数。示例性地，R 4选自H或C 1-3烷基，m为0-2之间的整数；
    所述聚乙二醇链段具有式3所示重复单元：
    Figure PCTCN2021094181-appb-100005
    所述聚丙二醇链段具有式4所示重复单元：
    Figure PCTCN2021094181-appb-100006
    所述聚乙二硫醇链段具有式5所示重复单元：
    Figure PCTCN2021094181-appb-100007
    所述聚碳酸酯链段具有式6所示重复单元：
    Figure PCTCN2021094181-appb-100008
    所述聚硅醚链段具有式7所示重复单元：
    Figure PCTCN2021094181-appb-100009
  4. 根据权利要求1-3任一项所述的正极极片，其中，所述聚合物选自聚苯醚聚丙烯酸酯、聚乙二醇聚甲基丙烯酸甲酯、聚乙二硫醇聚甲基丙烯酸甲酯、聚碳酸酯聚丙烯酸酯、聚丙二醇聚甲基丙烯酸酯、聚硅醚聚甲基丙烯酸甲酯中的至少一种。
  5. 根据权利要求1-4任一项所述的正极极片，其中，制备所述聚合物的单体选自如下式8所示化合物：
    Figure PCTCN2021094181-appb-100010
    式8中，R 1、R 2、R 3、M的定义如上所述。
  6. 根据权利要求5所述的正极极片，其中，所述式8所示化合物选自聚苯醚丙烯酸酯、聚乙二醇甲基丙烯酸甲酯、聚碳酸酯丙烯酸酯、聚丙二醇甲基丙烯酸酯、聚磺酸锂甲基丙烯酸酯、聚硅醚甲基丙烯酸甲酯中的至少一种。
  7. 根据权利要求1-6任一项所述的正极极片，其中，所述正极活性物质层包括如下质量百分含量的各组分：70-95wt％的正极活性物质、2-15wt％的导电剂、3-28wt％的所述的聚合物电解质、0-10wt％粘结剂。
  8. 根据权利要求1-7任一项所述的正极极片，其中，所述聚合物电解质中，所述聚合物中除碳、氢以外的其他元素与锂盐中锂元素的摩尔比为5:1-25:1。
  9. 根据权利要求1-8任一项所述的正极极片，其中，所述正极极片的孔隙率为0％-5％；和/或所述正极极片中的正极活性物质层的延长拉伸率为5％-500％。
  10. 一种固态电池，所述固态电池包括权利要求1-9任一项所述的正极极片。
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CN107591536A (zh) * 2017-09-02 2018-01-16 清陶（昆山）能源发展有限公司 凝胶复合正极片及其制备方法和制备全固态锂电池的方法
CN110943249A (zh) * 2018-09-25 2020-03-31 深圳市比亚迪锂电池有限公司 聚合物电解质和锂离子电池
CN110003399A (zh) * 2019-03-06 2019-07-12 南开大学 一种单离子导电聚合物电解质膜的制备及应用

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WO2024055390A1 (zh) * 2022-09-15 2024-03-21 宁德时代新能源科技股份有限公司 聚合物、正极材料组合物及其应用

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