WO2024255280A1 - 正极片、锂离子电池和储能设备 - Google Patents

正极片、锂离子电池和储能设备 Download PDF

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WO2024255280A1
WO2024255280A1 PCT/CN2024/076150 CN2024076150W WO2024255280A1 WO 2024255280 A1 WO2024255280 A1 WO 2024255280A1 CN 2024076150 W CN2024076150 W CN 2024076150W WO 2024255280 A1 WO2024255280 A1 WO 2024255280A1
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positive electrode
active material
electrode active
material layer
lithium
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French (fr)
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李玲霞
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Xiamen Hithium Energy Storage Technology Co Ltd
Shenzhen Hithium Energy Storage Technology Co Ltd
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Xiamen Hithium Energy Storage Technology Co Ltd
Shenzhen Hithium Energy Storage Technology Co Ltd
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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/251—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders specially adapted for stationary devices, e.g. power plant buffering or backup power supplies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a positive electrode sheet, a lithium-ion battery and an energy storage device.
  • Lithium-ion batteries are increasingly used in energy storage fields such as mobile devices, power tools, and electric vehicles due to their high operating voltage and specific energy density.
  • energy storage fields such as mobile devices, power tools, and electric vehicles due to their high operating voltage and specific energy density.
  • service life and energy efficiency of lithium-ion batteries have become key points to meet user needs.
  • the existing lithium-ion batteries have low discharge energy efficiency during use, resulting in incomplete discharge and insufficient utilization of the lithium-ion batteries during use. In view of this, it is necessary to further improve the existing lithium-ion batteries to improve the discharge energy efficiency of the lithium-ion batteries.
  • the present disclosure aims to solve at least one of the technical problems in the related art to a certain extent.
  • the purpose of the present disclosure is to provide a positive electrode sheet, a lithium-ion battery and an energy storage device.
  • the present disclosure significantly reduces the resistance of lithium ions to diffuse in the positive electrode sheet, and at the same time reduces the polarization of lithium ions in the diffusion process of the positive electrode sheet, thereby improving the cycle performance and energy efficiency of the lithium-ion battery.
  • the present disclosure provides a positive electrode sheet.
  • the positive electrode sheet includes: a positive electrode current collector;
  • a positive electrode active material layer is arranged on at least a portion of the surface of the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, the positive electrode active material is doped with a metal element M, and the metal element M is used to enhance the ability of the positive electrode active material to deintercalate lithium ions;
  • the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer decreases successively, and along the thickness direction of the positive electrode sheet, the ratio of the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer closest to the positive electrode current collector to the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer farthest from the positive electrode current collector is less than or equal to 8.
  • the present disclosure provides a lithium-ion battery.
  • the lithium-ion battery has the positive electrode sheet of the above embodiment, thereby improving the cycle performance and energy efficiency of the lithium-ion battery.
  • the present disclosure proposes an energy storage device.
  • the energy storage device has a lithium-ion battery as described above. Therefore, the energy storage device has all the advantages of the lithium-ion battery, which will not be repeated here.
  • FIG. 1 is a schematic structural diagram of a positive electrode sheet according to an embodiment of the present disclosure.
  • the present disclosure provides a positive electrode sheet.
  • positive electrode current collector positive electrode active material layer, the positive electrode active material layer is arranged on at least part of the surface of the positive electrode current collector, the positive electrode active material layer includes positive electrode active material, the positive electrode active material is doped with metal element M, and the metal element M is used to enhance the deintercalation ability of the positive electrode active material for lithium ions; assuming that the direction from the positive electrode current collector to the positive electrode active material layer is the thickness direction of the positive electrode sheet, along the thickness direction away from the positive electrode current collector, the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer decreases successively, and along the thickness direction of the positive electrode sheet, the ratio of the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer closest to the positive electrode current collector to the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer
  • the improvement of the lithium ion deintercalation ability of the positive electrode active material in the positive electrode active material layer by the doped metal element M decreases successively, thereby significantly reducing the difference in lithium ion deintercalation ability of the active materials in the upper and lower layers of the positive electrode sheet, improving the utilization of the active materials in the active material layer (i.e., the lower layer) closer to the positive electrode current collector, and reducing the failure risk of the active materials in the active material layer (i.e., the upper layer) farther from the positive electrode current collector, the discharge energy is improved, and its cycle performance and energy efficiency are improved by about 5% to 20%, thereby improving the cycle performance and energy efficiency of the lithium ion battery as a whole.
  • the active material in the active material layer far from the positive current collector releases more lithium ions, causing the active material in the active material layer far from the positive current collector to easily cause failure, while the capacity of the active material in the active material layer close to the positive current collector cannot be exerted, resulting in reduced energy efficiency and cycle life of the lithium ion battery.
  • the present invention dopes metal elements M into the positive electrode active material in the positive electrode active material layer to enhance the deintercalation ability of the positive electrode active material for lithium ions, and along the thickness direction away from the positive electrode current collector, the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer decreases successively. It should be noted that within a reasonable doping amount range, the higher the doping amount of the metal element M in the positive electrode active material, the greater the improvement in the lithium ion deintercalation ability of the positive electrode active material.
  • the improvement of the lithium ion deintercalation ability of the material decreases successively, thereby significantly reducing the difference in the lithium ion deintercalation ability of the active materials in the upper and lower layers of the positive electrode sheet, reducing the polarization of lithium ions in the diffusion process of the positive electrode sheet, improving the utilization of the active materials in the active material layer (i.e., the lower layer) closer to the positive electrode current collector, and reducing the failure risk of the active materials in the active material layer (i.e., the upper layer) farther away from the positive electrode current collector, the discharge energy is improved, and the cycle performance and energy efficiency are improved by about 5% to 20%, thereby improving the cycle performance and energy efficiency of lithium-ion batteries as a whole.
  • the inventors found that after doping the positive electrode active material (such as lithium iron phosphate) with the metal element M, the Li-O bond energy in the positive electrode active material (such as lithium iron phosphate) is weakened, vacancies appear inside the structure, the diffusion channel becomes wider, and the lithium ion diffusion resistance is reduced, thereby making it easier for lithium ions to be deintercalated.
  • the positive electrode active material such as lithium iron phosphate
  • the metal element M the Li-O bond energy in the positive electrode active material (such as lithium iron phosphate) is weakened, vacancies appear inside the structure, the diffusion channel becomes wider, and the lithium ion diffusion resistance is reduced, thereby making it easier for lithium ions to be deintercalated.
  • lithium iron phosphate As an example, after doping lithium iron phosphate with the metal element M, the metal element M replaces part of the iron element in the lithium iron phosphate lattice, thereby weakening the Li-O bond energy in the lithium iron phosphate lattice, vacancies appear inside the structure, the diffusion channel becomes wider, and the lithium ion diffusion resistance is reduced, thereby making it easier for lithium ions to be deintercalated.
  • the positive electrode active material layer includes: a first positive electrode active material layer 200, the first positive electrode active material layer 200 is disposed on at least a portion of the surface of the positive electrode current collector 100; a second positive electrode active material layer 300, the second positive electrode active material layer 300 is disposed on at least a portion of the surface of the first positive electrode active material layer 200 away from the positive electrode current collector 100; and the ratio of the doping amount of the metal element M of the positive electrode active material in the first positive electrode active material layer 200 to the doping amount of the metal element M of the positive electrode active material in the second positive electrode active material layer 300 is less than or equal to 8.
  • the difference in the ability of the active material of the first positive electrode active material layer and the second positive electrode active material layer to deintercalate lithium ions is reduced, the utilization of the active material in the first positive electrode active material layer is improved, and the failure risk of the active material in the second positive electrode active material layer is reduced, and the cycle performance and energy efficiency thereof are improved by about 5% to 20%, thereby improving the cycle performance and energy efficiency of the lithium ion battery as a whole.
  • the number of layers of each sub-positive electrode active material layer is not particularly limited, and may be two layers, three layers, four layers, five layers, etc.
  • the content of positive electrode active material in each sub-positive electrode active material layer is the same.
  • the direction from the positive current collector to the positive active material layer is the direction from A to B, and the direction from A to B is the thickness direction of the positive electrode sheet.
  • the positive electrode active material layer closest to the positive current collector 100 is the first positive electrode active material layer 200
  • the positive electrode active material layer farthest from the positive current collector 100 is the second positive electrode active material layer 300.
  • the ratio of the doping amount of the metal element M of the positive electrode active material in the first positive electrode active material layer to the doping amount of the metal element M of the positive electrode active material in the second positive electrode active material layer to less than or equal to 8
  • the difference in the ability of the active material of the first positive electrode active material layer and the second positive electrode active material layer to deintercalate lithium ions can be effectively reduced.
  • the ratio of the doping amount of the metal element M of the positive electrode active material in the first positive electrode active material layer to the doping amount of the metal element M of the positive electrode active material in the second positive electrode active material layer is 3-5.
  • the doping amount of the metal element M of the positive electrode active material in the first positive electrode active material layer is 2000ppm-7000ppm; and/or, the doping amount of the metal element M of the positive electrode active material in the second positive electrode active material layer is 500ppm-2000ppm.
  • the doping amount of the metal element M of the positive electrode active material in the first positive electrode active material layer and the doping amount of the metal element M of the positive electrode active material in the second positive electrode active material layer to the above range, the difference in the ability of the active material of the first positive electrode active material layer and the second positive electrode active material layer to deintercalate lithium ions is further reduced, the utilization of the active material in the first positive electrode active material layer is improved, and the failure risk of the active material in the second positive electrode active material layer is reduced, and the cycle performance and energy efficiency thereof are improved by about 5% to 20%, thereby improving the cycle performance and energy efficiency of the lithium ion battery as a whole.
  • the doping amount of the metal element M refers to the content of the metal element M based on the total mass of the positive electrode active material doped with the metal element M.
  • the specific types of the above-mentioned positive electrode active materials are not particularly limited, and those skilled in the art can flexibly select according to actual needs.
  • the positive electrode active material includes at least one of lithium iron phosphate, lithium nickelate, lithium manganate, lithium cobaltate, lithium manganese phosphate, lithium vanadium phosphate, nickel cobalt aluminum lithium oxide and nickel cobalt manganese lithium oxide. Lithium iron phosphate is preferred.
  • the type of the positive electrode active material in the first positive electrode active material layer may be the same as or different from the type of the positive electrode active material in the second positive electrode active material layer.
  • the positive electrode active material in the first positive electrode active material layer and the positive electrode active material in the second positive electrode active material layer are both lithium iron phosphate.
  • the specific type of the above-mentioned doped metal element M is not particularly limited and can be selected according to the specific type of the positive electrode active material.
  • the metal element M doped in lithium iron phosphate should have an atomic radius that is not much different from that of the iron element, so that the metal element M can replace part of the iron element in the lithium iron phosphate lattice.
  • the metal element M can be selected from at least one of Ti, V, Mg and Al, preferably Ti.
  • the type of the metal element M doped in the positive electrode active material in the first positive electrode active material layer and the type of the metal element M doped in the positive electrode active material in the second positive electrode active material layer may be the same or different.
  • the positive electrode active material in the first positive electrode active material layer and the positive electrode active material in the second positive electrode active material layer are both doped with metal Element Ti.
  • the lithium ions in the active material layer far from the positive electrode current collector are easy to deintercalate (i.e., the lithium ions of the active material in the upper layer of the electrode sheet are easy to deintercalate), and the lithium ions in the active material layer close to the positive electrode current collector are not easy to deintercalate (i.e., the lithium ions of the active material in the lower layer of the electrode sheet are not easy to deintercalate), which easily causes polarization during the charge and discharge process.
  • the present disclosure reduces the difference in the ability of the active materials in the upper and lower layers of the positive electrode sheet to deintercalate lithium ions by providing multiple layers of active material layers, and the doping amount of the metal element M in the active material layer close to the positive electrode current collector is higher, and the doping amount of the metal element M in the active material layer far from the positive electrode current collector is lower.
  • the surface density of the first positive electrode active material layer is 150mg/ 1540.12mm2-250mg / 1540.12mm2 ; and/or, the surface density of the second positive electrode active material layer is 150mg/ 1540.12mm2-250mg / 1540.12mm2 .
  • the difference in the ability of the active materials of the first positive electrode active material layer and the second positive electrode active material layer to deintercalate lithium ions is further reduced, the utilization of the active materials in the first positive electrode active material layer is improved, and the failure risk of the active materials in the second positive electrode active material layer is reduced, and the cycle performance and energy efficiency thereof are improved by about 5% to 20%, thereby generally improving the cycle performance and energy efficiency of the lithium ion battery.
  • the positive electrode active material layer includes, in addition to the positive electrode active material, a conductive agent, a binder and a dispersant, and the mass ratio of the positive electrode active material, the conductive agent, the binder and the dispersant is (94.5-98.5): (0.5-2.0): (1-3.0): (0-1).
  • the conductive agent includes, but is not limited to, at least one of acetylene black, Super P, carbon nanotubes, graphene and conductive carbon fibers.
  • the binder includes, but is not limited to, at least one of PVDF, PTFE and NBR.
  • the ICP test method may be used to test the doping amount of the metal element M of the positive electrode active material in the positive electrode active material layer.
  • the preparation method of the positive electrode sheet is as follows:
  • positive electrode active materials, conductive agents, binders and dispersants with different metal element doping amounts are weighed according to a predetermined mass ratio, and solvents are added respectively and stirred and mixed in a certain manner to form positive electrode slurries.
  • the solid content of the positive electrode slurry is not particularly limited, for example, the solid content is 40% to 80%.
  • the specific type of solvent is also not particularly limited, for example, at least one of NMP (N-methylpyrrolidone), DMF (dimethylformamide) and DMSO can be selected.
  • a positive electrode active material with a metal element doping amount of 2000ppm to 3000ppm, a conductive agent, a binder, a dispersant and a solvent are mixed to form a first positive electrode slurry, and a positive electrode active material with a metal element doping amount of 500ppm to 1500ppm, a conductive agent, a binder, a dispersant and a solvent are mixed to form a second positive electrode slurry.
  • step (1) The positive electrode slurries prepared in step (1) are respectively applied to the positive electrode current collector, and are applied to the positive electrode current collector in order of metal element doping from high to low, and then dried to form positive electrode sheets. Finally, the positive electrode sheets are cut into specific shapes according to the different battery shells for use.
  • a first positive electrode slurry with a metal element doping amount of 2000ppm to 3000ppm is first applied to the positive electrode collector, and a first positive electrode active material layer is formed after drying. Then, a second positive electrode slurry with a metal element doping amount of 500ppm to 1500ppm is applied to the surface of the first positive electrode active material layer away from the positive electrode collector, and a second positive electrode active material layer is formed after drying.
  • the coating area density of the first positive electrode active material layer is about 150 mg/1540.12 mm 2 to 250 mg/1540.12 mm 2
  • the coating area density of the second positive electrode active material layer is about 150 mg/1540.12 mm 2 to 250 mg/1540.12 mm 2 .
  • the present disclosure provides a lithium-ion battery.
  • the lithium-ion battery has the positive electrode sheet of the above embodiment, thereby improving the cycle performance and energy efficiency of the lithium-ion battery.
  • the lithium-ion battery comprises the positive electrode sheet, the negative electrode sheet and the separator of the above embodiment, and the separator is arranged between the positive electrode sheet and the negative electrode sheet.
  • the separator comprises at least one of a PP separator, a PE separator, a single-sided ceramic separator, a double-sided ceramic separator, a non-woven separator and a glass fiber separator.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material (e.g., graphite), a negative electrode dispersant, a conductive agent, a negative electrode binder, and a plasticizer.
  • a negative electrode active material e.g., graphite
  • the mass ratio of the negative electrode active material, the negative electrode dispersant, the conductive agent, the negative electrode binder, and the plasticizer is (97-98.5): (1.2-1.6): (0.4-2.0): (1.3-2.3): (1-2).
  • Preparation of battery cells Add separators to the positive and negative electrode sheets and wind them up. After winding, weld the positive and negative electrode tabs. Then encapsulate the bare battery cells in aluminum-plastic film. After encapsulation, vacuum bake the battery cells for 10 to 20 hours. Then, after liquid injection, standing, high-temperature and high-pressure formation, degassing packaging, and capacity division, a lithium-ion battery with a double-layer coated positive electrode is obtained.
  • the present disclosure proposes an energy storage device.
  • the energy storage device has the lithium-ion battery as described above. Therefore, the energy storage device has all the advantages of the lithium-ion battery, which will not be repeated here.
  • This embodiment provides a lithium ion battery, and the preparation method thereof includes:
  • Preparation of the first positive electrode slurry lithium iron phosphate, conductive agent C, binder PVDF and dispersant PVP were weighed according to the mass ratio, wherein the doping amount of Ti element in lithium iron phosphate was 2500ppm, and the mass ratio of lithium iron phosphate, conductive agent, binder and dispersant was 96.5:1.25:2:0.5. NMP solvent was added and stirred to form the first positive electrode slurry, whose solid content was 60%.
  • lithium iron phosphate, conductive agent, binder and dispersant are weighed by mass, wherein the doping amount of Ti element in lithium iron phosphate is 750ppm, and the mass ratio of lithium iron phosphate, conductive agent, binder and dispersant is 96.5:1.25:2:0.5. Add solvent and stir to form the second positive electrode slurry, whose solid content is 60%.
  • the first positive electrode slurry formed in step a is applied to the first positive electrode current collector layer with a coating surface density of about 200 mg/1540.12 mm2 , and then dried;
  • the second positive electrode slurry formed in step b is applied to the second positive electrode current collector layer with a coating surface density of about 200 mg/1540.12 mm2 , and then dried;
  • the obtained positive electrode sheet is rolled and cut to obtain the final positive electrode sheet.
  • Step (2) The negative electrode slurry obtained in step (2) is evenly coated on the negative electrode current collector, dried, and the obtained electrode sheet is rolled and cut to obtain the negative electrode sheet.
  • Preparation of battery cells Add separators to the positive and negative electrode sheets and wind them up, weld the positive and negative electrode tabs after winding, and then package the bare battery cells in aluminum plastic films. After packaging, vacuum bake the battery cells for 15 hours, and then undergo liquid injection, standing, high temperature and high pressure formation, degassing packaging, and volume separation to obtain a lithium ion battery with a double-layer coated positive electrode.
  • the electrolyte of the lithium ion battery includes lithium hexafluorophosphate and dimethyl carbonate, wherein the concentration of lithium hexafluorophosphate is 1 mol/L.
  • This embodiment provides a lithium ion battery, which is different from the first embodiment in that:
  • step a the doping amount of Ti element in lithium iron phosphate is 3500 ppm;
  • step b the doping amount of Ti element in lithium iron phosphate is 1500 ppm.
  • This embodiment provides a lithium ion battery, which is different from the first embodiment in that:
  • step a the doping amount of Ti element in lithium iron phosphate is 4500 ppm;
  • step b the doping amount of Ti element in lithium iron phosphate is 1500 ppm.
  • This embodiment provides a lithium ion battery, which is different from the first embodiment in that:
  • step a the doping amount of Ti element in lithium iron phosphate is 5500 ppm;
  • step b the doping amount of Ti element in lithium iron phosphate is 1500 ppm.
  • This embodiment provides a lithium ion battery, which is different from the first embodiment in that:
  • step a the doping amount of Ti element in lithium iron phosphate is 6500 ppm;
  • step b the doping amount of Ti element in lithium iron phosphate is 1500 ppm.
  • This comparative example provides a lithium ion battery, which is different from Example 1 in that:
  • step a the doping amount of Ti element in lithium iron phosphate is 750 ppm;
  • step b the doping amount of Ti element in lithium iron phosphate is 750 ppm.
  • step a the doping amount of Ti element in lithium iron phosphate is 1500 ppm;
  • step b the doping amount of Ti element in lithium iron phosphate is 1500 ppm.
  • Cycle performance test At 25°C, the batteries prepared in Examples 1-5 and Comparative Examples 1-2 were charged to 3.65V at a rate of 1P and discharged to 2.5V at a rate of 1P, and full charge and discharge cycle tests were performed until the capacity of the lithium-ion battery was less than 80% of the initial capacity. The number of cycles and energy efficiency were recorded. The test results are shown in Table 1.

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Abstract

本公开公开了正极片、锂离子电池和储能设备，正极片包括正极集流体；正极活性物质层，正极活性物质层设置在正极集流体的至少部分表面，正极活性物质层中包括正极活性物质，正极活性物质中掺杂有金属元素M；沿着远离正极集流体的厚度方向，正极活性物质层中的正极活性物质的金属元素M的掺杂量依次降低，且距离正极集流体最近处的正极活性物质层中的正极活性物质的金属元素M的掺杂量与距离正极集流体最远处的正极活性物质层中的正极活性物质的金属元素M的掺杂量的比值小于等于8。

Description

正极片、锂离子电池和储能设备
优先权信息
本申请请求2023年06月16日向中国国家知识产权局提交的、专利申请号为2023107180220的专利申请的优先权和权益，并且通过参照将其全文并入此处。
技术领域
本公开属于锂离子电池技术领域，具体涉及一种正极片、锂离子电池和储能设备。
背景技术
目前化石能源仍然是全球能源消费的主要方式，比例高达85％。可再生能源消费仅占全球能源消费的10％，而西方国家要在2050年之前实现碳中和，可再生能源消费占比必须要达到30％以上。风能、光能作为未来实现碳中和的重要手段，因其不稳定性、易冲击电网等缺点，导致其商业化应用步伐较慢。因此储能的出现，将解决发电侧的这些弊端问题。储能是保证高比例新能源接入后，电力系统保持安全稳定运行的必然选择。
锂离子电池由于具有较高的工作电压和比能量密度，使其在移动设备、电动工具以及电动汽车等储能领域的应用越来越广泛。当然，随着用户需求的不断提升，锂离子电池的使用寿命以及能量效率成为满足用户需求的关键点。
现有的锂离子电池在使用过程中的放电能量效率较低，导致锂离子电池在应用过程中放电不完全，利用不充分。有鉴于此，有必要对现有的锂离子电池进行进一步地改进，以提高锂离子电池的放电能量效率。
公开内容
本公开旨在至少在一定程度上解决相关技术中的技术问题之一。为此，本公开的目的在于提出一种正极片、锂离子电池和储能设备。本公开显著降低了锂离子在正极片中扩散的阻力，同时减小了锂离子在正极片的扩散过程中的极化，从而提升了锂离子电池的循环性能和能量效率。
在本公开的一个方面，本公开提出了一种正极片。根据本公开的实施方式，所述正极片包括：正极集流体；
正极活性物质层，所述正极活性物质层设置在所述正极集流体的至少部分表面，所述正极活性物质层中包括正极活性物质，所述正极活性物质中掺杂有金属元素M，所述金属元素M用于增强所述正极活性物质对锂离子的脱嵌能力；
设从所述正极集流体向所述正极活性物质层的方向为所述正极片的厚度方向，沿着远 离所述正极集流体的厚度方向，所述正极活性物质层中的正极活性物质的所述金属元素M的掺杂量依次降低，且沿着所述正极片的厚度方向，距离所述正极集流体最近处的所述正极活性物质层中的正极活性物质的所述金属元素M的掺杂量与距离所述正极集流体最远处的所述正极活性物质层中的正极活性物质的所述金属元素M的掺杂量的比值小于等于8。
根据本公开实施方式的正极片，在正极活性物质中掺杂金属元素M从整体上提升了正极活性物质层中的正极活性物质对锂离子的脱嵌能力，且对距离正极集流体最近处的正极活性物质层(即下层)中的正极活性物质的锂离子脱嵌能力的提升最大，沿着远离所述正极集流体的厚度方向，掺杂的金属元素M对正极活性物质层中的正极活性物质的锂离子脱嵌能力的提升依次降低，由此显著降低了正极片的上层和下层的活性物质对锂离子脱嵌能力的差异，提高了距离正极集流体较近的活性物质层(即下层)中的活性物质的利用，并且降低了距离正极集流体较远的活性物质层(即上层)中的活性物质的失效风险，放电能量得到提升，其循环性能与能量效率提升了5％～20％左右，从而从总体上提高了锂离子电池的循环性能和能量效率。
在本公开的第二个方面，本公开提出了一种锂离子电池。根据本公开的实施方式，锂离子电池具有以上实施方式的正极片。由此，提高了锂离子电池的循环性能和能量效率。
在本公开的第三个方面，本公开提出了一种储能设备。根据本公开的实施方式，所述储能设备具有如上所述的锂离子电池。由此，所述储能设备具有所述锂离子电池的所有优点，在此不再赘述。
本公开的附加方面和优点将在下面的描述中部分给出，部分将从下面的描述中变得明显，或通过本公开的实践了解到。
附图说明
本公开的上述和/或附加的方面和优点从结合下面附图对实施方式的描述中将变得明显和容易理解，其中：
图1为本公开一个实施方式的正极片的结构示意图。
附图标注，100-正极集流体，200-第一正极活性物质层，300-第二正极活性物质层。
发明详细描述
下面详细描述本公开的实施方式，所述实施方式的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施方式是示例性的，旨在用于解释本公开，而不能理解为对本公开的限制。
在本公开的一个方面，本公开提出了一种正极片。根据本公开的实施方式，参考附图 1-3，正极集流体；正极活性物质层，正极活性物质层设置在正极集流体的至少部分表面，正极活性物质层中包括正极活性物质，正极活性物质中掺杂有金属元素M，金属元素M用于增强正极活性物质对锂离子的脱嵌能力；设从正极集流体向正极活性物质层的方向为正极片的厚度方向，沿着远离正极集流体的厚度方向，正极活性物质层中的正极活性物质的金属元素M的掺杂量依次降低，且沿着正极片的厚度方向，距离正极集流体最近处的正极活性物质层中的正极活性物质的金属元素M的掺杂量与距离正极集流体最远处的正极活性物质层中的正极活性物质的金属元素M的掺杂量的比值小于等于8。由此，在正极活性物质中掺杂金属元素M从整体上提升了正极活性物质层中的正极活性物质对锂离子的脱嵌能力，且对距离正极集流体最近处的正极活性物质层(即下层)中的正极活性物质的锂离子脱嵌能力的提升最大，沿着远离正极集流体的厚度方向，掺杂的金属元素M对正极活性物质层中的正极活性物质的锂离子脱嵌能力的提升依次降低，由此显著降低了正极片的上层和下层的活性物质对锂离子脱嵌能力的差异，提高了距离正极集流体较近的活性物质层(即下层)中的活性物质的利用，并且降低了距离正极集流体较远的活性物质层(即上层)中的活性物质的失效风险，放电能量得到提升，其循环性能与能量效率提升了5％～20％左右，从而从总体上提高了锂离子电池的循环性能和能量效率。
下面对本公开提出的正极片能够实现上述有益效果的原理进行详细说明：
发明人发现，尤其是在厚涂敷的正电极片中，由于活性物质层涂敷较厚，导致锂离子在扩散传输过程中，距离正极集流体较远的活性物质层中的锂离子容易脱嵌(即电极片上层的活性物质的锂离子容易脱嵌)，距离正极集流体较近的活性物质层中的锂离子不易脱嵌(即电极片下层的活性物质的锂离子不易脱嵌)，从而导致在充放电过程中容易引起极化。长期的循环过程中，距离正极集流体较远的活性物质层中的活性物质脱出较多的锂离子，导致距离正极集流体较远的活性物质层中的活性物质容易引起失效，而距离正极集流体较近的活性物质层中的活性物质的容量发挥不出来，从而导致锂离子电池的能量效率降低以及循环寿命减少。
为了解决该问题，本公开通过在正极活性物质层的正极活性物质中掺杂金属元素M，以增强正极活性物质对锂离子的脱嵌能力，且沿着远离正极集流体的厚度方向，正极活性物质层中的正极活性物质的金属元素M的掺杂量依次降低。需要说明的是，在合理的掺杂量范围内，正极活性物质中的金属元素M的掺杂量越高，则对正极活性物质的锂离子脱嵌能力的提升越大。由此，在正极活性物质中掺杂金属元素M从整体上提升了正极活性物质层中的正极活性物质对锂离子的脱嵌能力，使锂离子在正极片中扩散阻力减小，且对距离正极集流体最近处的正极活性物质层(即下层)中的正极活性物质的锂离子脱嵌能力的提升最大，沿着远离正极集流体的方向，掺杂的金属元素M对正极活性物质层中的正极活性 物质的锂离子脱嵌能力的提升依次降低，由此显著降低了正极片的上层和下层的活性物质对锂离子脱嵌能力的差异，使锂离子在正极片的扩散过程中极化减小，提高了距离正极集流体较近的活性物质层(即下层)中的活性物质的利用，并且降低了距离正极集流体较远的活性物质层(即上层)中的活性物质的失效风险，放电能量得到提升，其循环性能与能量效率提升了5％～20％左右，从而从总体上提高了锂离子电池的循环性能和能量效率。
发明人发现，在正极活性物质(例如磷酸铁锂)中掺杂金属元素M后，正极活性物质(例如磷酸铁锂)中Li-O键能减弱，结构内部出现空缺，扩散通道变宽，锂离子扩散阻力减小，从而使锂离子更容易脱嵌。以磷酸铁锂为例来说，在磷酸铁锂中掺杂金属元素M后，金属元素M替换磷酸铁锂晶格中的部分铁元素，使磷酸铁锂晶格中的Li-O键能减弱，结构内部出现空缺，扩散通道变宽，锂离子扩散阻力减小，从而使锂离子更容易脱嵌。
发明人发现，通过将距离正极集流体最近处的正极活性物质层(即下层)中的正极活性物质的金属元素M的掺杂量与距离正极集流体最远处的正极活性物质层(上层)中的正极活性物质的金属元素M的掺杂量的比值限定为小于等于8范围内，可有效降低正极片的上层和下层的活性物质对锂离子脱嵌能力的差异，如果该比值大于8，很可能会因为下层正极活性物质的金属元素M的掺杂量过高而导致下层正极活性物质对锂离子脱嵌能力大于上层正极活性物质对锂离子脱嵌能力，从而导致下层正极活性物质失效的风险提升，反而不利于其循环性能与能量效率的提升。
根据本公开的一些具体实施方式，参考附图1，正极活性物质层包括：第一正极活性物质层200，第一正极活性物质层200设置在正极集流体100的至少部分表面；第二正极活性物质层300，第二正极活性物质层300设置在第一正极活性物质层200的远离正极集流体100的至少部分表面；且第一正极活性物质层200中的正极活性物质的金属元素M的掺杂量与第二正极活性物质层300中的正极活性物质的金属元素M的掺杂量的比值小于等于8。由此，降低了第一正极活性物质层和第二正极活性物质层的活性物质对锂离子脱嵌能力的差异，提高了第一正极活性物质层中的活性物质的利用，并且降低了第二正极活性物质层中的活性物质的失效风险，其循环性能与能量效率提升了5％～20％左右，从而从总体上提高了锂离子电池的循环性能和能量效率。需要说明的是，各子正极活性物质层的层数并不受特别限定，可以是两层，也可以是三层、四层、五层等。优选地，各子正极活性物质层中的正极活性物质的含量相同。
作为一些具体示例，在附图1中，从正极集流体向正极活性物质层的方向就是A到B的方向，A到B的方向即是正极片的厚度方向，沿着正极片的厚度方向，距离正极集流体100最近处的正极活性物质层就是第一正极活性物质层200，距离正极集流体100最远处的正极活性物质层就是第二正极活性物质层300。
进一步地，通过将第一正极活性物质层中的正极活性物质的金属元素M的掺杂量与第二正极活性物质层中的正极活性物质的金属元素M的掺杂量的比值限定为小于等于8范围内，可有效降低第一正极活性物质层与第二正极活性物质层的活性物质对锂离子脱嵌能力的差异，如果该比值大于8，很可能会因为第一正极活性物质层中的正极活性物质的金属元素M的掺杂量过高而导致第一正极活性物质层的正极活性物质对锂离子脱嵌能力大于第二正极活性物质层的正极活性物质对锂离子脱嵌能力，从而导致第一正极活性物质层的正极活性物质失效的风险提升，反而不利于其循环性能与能量效率的提升。优选地，第一正极活性物质层中的正极活性物质的金属元素M的掺杂量与第二正极活性物质层中的正极活性物质的金属元素M的掺杂量的比值为3-5。
进一步地，第一正极活性物质层中的正极活性物质的金属元素M的掺杂量为2000ppm-7000ppm；和/或，第二正极活性物质层中的正极活性物质的金属元素M的掺杂量为500ppm～2000ppm。通过将第一正极活性物质层中的正极活性物质的金属元素M的掺杂量和第二正极活性物质层中的正极活性物质的金属元素M的掺杂量限定在上述范围内，进一步降低了第一正极活性物质层和第二正极活性物质层的活性物质对锂离子脱嵌能力的差异，提高了第一正极活性物质层中的活性物质的利用，并且降低了第二正极活性物质层中的活性物质的失效风险，其循环性能与能量效率提升了5％～20％左右，从而从总体上提高了锂离子电池的循环性能和能量效率。
需要说明的是，金属元素M的掺杂量指的是：基于掺杂有金属元素M的正极活性物质的总质量，金属元素M的含量。
在本公开的实施方式中，上述正极活性物质的具体种类并不受特别限定，本领域人员可根据实际需求灵活选择，作为一些具体示例，正极活性物质包括磷酸铁锂、镍酸锂、锰酸锂、钴酸锂、磷酸锰锂、磷酸钒锂、镍钴铝锂氧化物和镍钴锰锂氧化物中的至少一种。优选磷酸铁锂。另外，第一正极活性物质层中的正极活性物质的种类与第二正极活性物质层中的正极活性物质的种类可以相同也可以不相同，优选地，第一正极活性物质层中的正极活性物质与第二正极活性物质层中的正极活性物质均为磷酸铁锂。
在本公开的实施方式中，上述掺杂的金属元素M的具体种类并不受特别限定，可根据正极活性物质的具体种类来选择。例如磷酸铁锂中掺杂的金属元素M要与铁元素的原子半径相差不大，以便金属元素M能够替换磷酸铁锂晶格中的部分铁元素，当正极活性物质为磷酸铁锂时，金属元素M可以选择Ti、V、Mg和Al中的至少一种，优选Ti元素。需要说明的是，第一正极活性物质层中的正极活性物质中掺杂金属元素M的种类与第二正极活性物质层中的正极活性物质中掺杂金属元素M的种类可以相同也可以不相同，优选地，第一正极活性物质层中的正极活性物质与第二正极活性物质层中的正极活性物质中均掺杂金属 元素Ti。
如前，在厚涂敷的正电极片中，例如正极活性物质层的面密度为300mg/1540.12mm2-500mg/1540.12mm2时，由于活性物质层涂敷较厚，导致锂离子在扩散传输过程中，距离正极集流体较远的活性物质层中的锂离子容易脱嵌(即电极片上层的活性物质的锂离子容易脱嵌)，距离正极集流体较近的活性物质层中的锂离子不易脱嵌(即电极片下层的活性物质的锂离子不易脱嵌)，从而导致在充放电过程中容易引起极化。本公开通过设置多层活性物质层，且距离正极集流体较近的活性物质层的金属元素M的掺杂量较高，距离正极集流体较远的活性物质层的金属元素M的掺杂量较低，由此来降低正极片的上层和下层的活性物质对锂离子脱嵌能力的差异。
进一步地，第一正极活性物质层的面密度为150mg/1540.12mm2-250mg/1540.12mm2；和/或，第二正极活性物质层的面密度为150mg/1540.12mm2-250mg/1540.12mm2。由此，进一步降低了第一正极活性物质层和第二正极活性物质层的活性物质对锂离子脱嵌能力的差异，提高了第一正极活性物质层中的活性物质的利用，并且降低了第二正极活性物质层中的活性物质的失效风险，其循环性能与能量效率提升了5％～20％左右，从而从总体上提高了锂离子电池的循环性能和能量效率。
在本公开的实施方式中，正极活性物质层中除了包括正极活性物质，还包括导电剂、粘结剂和分散剂，且正极活性物质、导电剂、粘结剂和分散剂的质量比为(94.5-98.5):(0.5-2.0):(1-3.0):(0-1)。导电剂包括但不限于乙炔黑、Super P、碳纳米管、石墨烯和导电碳纤维中的至少之一。粘结剂包括但不限于PVDF、PTFE和NBR中的至少一种。
在本公开的实施方式中，可采用ICP测试方法测试出正极活性物质层中的正极活性物质的金属元素M的掺杂量。
在本公开的实施方式中，上述正极片的制备方法如下：
(1)根据本领域常规制备正极片方法，按照预定的质量配比称取金属元素掺杂量不同的正极活性物质、导电剂、粘结剂和分散剂，分别加入溶剂按一定方式搅拌混合，分别形成正极浆料。正极浆料的固含量并不受特别限定，例如固含量为40％～80％。溶剂的具体种类也不受特别限定，例如可以选择NMP(N-甲基吡咯烷酮)、DMF(二甲基甲酰胺)以及DMSO中的至少一种。
例如，将金属元素掺杂量为2000ppm～3000ppm的正极活性物质、导电剂、粘结剂、分散剂和溶剂混合形成第一正极浆料，将金属元素掺杂量为500ppm～1500ppm的正极活性物质、导电剂、粘结剂、分散剂和溶剂混合形成第二正极浆料。
需要说明的是，不同金属元素掺杂量的正极活性物质的制备方法属于本领域的常规技术手段，在此不再赘述。
(2)将步骤(1)中制备的各正极浆料分别涂敷于正极集流体，且按照金属元素掺杂量从高到低的顺序依次涂敷于正极集流体，烘干后形成正极片。最后根据电池外壳的不同，切成特定形状的正极片备用。
例如先将金属元素掺杂量为2000ppm～3000ppm的第一正极浆料涂敷于正极集流体，烘干后形成第一正极活性物质层，然后将金属元素掺杂量为500ppm～1500ppm的第二正极浆料涂敷于第一正极活性物质层的远离正极集流体的表面，烘干后形成第二正极活性物质层。
优选地，第一正极活性物质层的涂敷面密度约150mg/1540.12mm2～250mg/1540.12mm2，和/或，第二正极活性物质层的涂敷面密度约150mg/1540.12mm2～250mg/1540.12mm2。
在本公开的第二个方面，本公开提出了一种锂离子电池。根据本公开的实施方式，锂离子电池具有以上实施方式的正极片。由此，提高了锂离子电池的循环性能和能量效率。
具体地，锂离子电池包括以上实施方式的正极片、负极片和和隔膜，隔膜设置在正极片和负极片之间。隔膜包括PP隔膜、PE隔膜、单面陶瓷隔膜、双面陶瓷隔膜、无纺布隔膜、玻璃纤维隔膜中的至少一种。
负极片包括负极集流体和形成在负极集流体上的负极活性材料层，负极活性材料层包括负极活性材料(例如石墨)、负极分散剂、导电剂、负极粘接剂和增塑剂。进一步地，负极活性材料、负极分散剂、导电剂、负极粘接剂和增塑剂的质量比为(97-98.5)：(1.2-1.6)：(0.4-2.0)：(1.3-2.3)：(1-2)。
负极片的制备方法包括：按照预设比例将负极活性材料、负极分散剂、导电剂、负极粘接剂和增塑剂混合均匀，加入溶剂搅拌均匀形成负极浆料，然后涂布到集流体上，烘干，最后根据电池外壳的不同，切成特定形状的负极片备用。进一步地，负极浆料的固含量为40％～60％。
电芯制备：对正极片、负极片加入隔膜进行卷绕，卷绕后进行正负极极耳焊接，然后将裸电芯封装于铝塑膜内，封装后对电芯真空烘烤10h～20h，然后经过注液、静置、高温高压化成、除气封装、分容，即得具有双层涂敷正极的锂离子电池。
在本公开的第三个方面，本公开提出了一种储能设备。根据本公开的实施方式，储能设备具有如上的锂离子电池。由此，储能设备具有锂离子电池的所有优点，在此不再赘述。
具体地，该储能设备可以包括用于电力系统的发电侧的电力储能装置、用于电力系统的配电侧的电力储能装置(例如电化学储能装置)和用于电力系统的用户侧的电力储能装置中的至少之一。
下面详细描述本公开的实施例，需要说明的是下面描述的实施例是示例性的，仅用于解释本公开，而不能理解为对本公开的限制。另外，如果没有明确说明，在下面的实施例 中所采用的所有试剂均为市场上可以购得的，或者可以按照本文或已知的方法合成的，对于没有列出的反应条件，也均为本领域技术人员容易获得的。
实施例1
本实施例提供一种锂离子电池，其制备方法包括：
(1)正极浆料的制备：
a.第一正极浆料的制备：按照质量比称取磷酸铁锂、导电剂C、粘结剂PVDF和分散剂PVP，其中磷酸铁锂中Ti元素的掺杂量为2500ppm，磷酸铁锂、导电剂、粘结剂和分散剂的质量比为96.5:1.25:2:0.5。加入NMP溶剂搅拌混合，形成第一正极浆料，其固含量为60％。
b.第二正极浆料的制备：按照质量称取磷酸铁锂、导电剂、粘结剂和分散剂，其中磷酸铁锂中Ti元素的掺杂量为750ppm，磷酸铁锂、导电剂、粘结剂和分散剂的质量比为96.5:1.25:2:0.5。加入溶剂搅拌混合，形成第二正极浆料，其固含量为60％。
(2)负极浆料的制备：按照质量比称取石墨、负极分散剂羧甲基纤维素钠、导电剂SP、负极粘接剂SBR和增塑剂丙二醇，其中石墨、负极分散剂、导电剂、负极粘接剂和增塑剂的质量比为97.75：1.4：1.2：1.8：1.5。加入水溶剂搅拌均匀形成负极浆料，形成负极浆料，其固含量为50％。
(3)正、负极片制备：
正极片的制备：将步骤a中形成的第一正极浆料涂敷于正极集流体第一层，涂敷面密度约200mg/1540.12mm2，烘干；步骤b中形成的第二正极浆料涂敷于正极集流体第二层，涂敷面密度约200mg/1540.12mm2，烘干；将得到的正极片经辊压、分切得最终的正极片。
负极片的制备：将步骤(2)得到的负极浆料均匀涂覆于负极集流体上，烘干，将得到的极片进行滚压分切，得到负极片。
(4)电芯制备：对正极片、负极片加入隔膜进行卷绕，卷绕后进行正负极极耳焊接，然后将裸电芯进行封装于铝塑膜内，封装后对电芯真空烘烤15h后，经过注液、静置、高温高压化成、除气封装、分容，即得具有双层涂敷正极的锂离子电池。该锂离子电池的电解液包括六氟磷酸锂和碳酸二甲酯，其中六氟磷酸锂的浓度为1mol/L。
实施例2
本实施例提供一种锂离子电池，与实施例1的区别在于：
在步骤a中，磷酸铁锂中Ti元素的掺杂量为3500ppm；
在步骤b中，磷酸铁锂中Ti元素的掺杂量为1500ppm。
其他内容均与实施例1相同。
实施例3
本实施例提供一种锂离子电池，与实施例1的区别在于：
在步骤a中，磷酸铁锂中Ti元素的掺杂量为4500ppm；
在步骤b中，磷酸铁锂中Ti元素的掺杂量为1500ppm。
其他内容均与实施例1相同。
实施例4
本实施例提供一种锂离子电池，与实施例1的区别在于：
在步骤a中，磷酸铁锂中Ti元素的掺杂量为5500ppm；
在步骤b中，磷酸铁锂中Ti元素的掺杂量为1500ppm。
其他内容均与实施例1相同。
实施例5
本实施例提供一种锂离子电池，与实施例1的区别在于：
在步骤a中，磷酸铁锂中Ti元素的掺杂量为6500ppm；
在步骤b中，磷酸铁锂中Ti元素的掺杂量为1500ppm。
其他内容均与实施例1相同。
对比例1
本对比例提供一种锂离子电池，与实施例1的区别在于：
在步骤a中，磷酸铁锂中Ti元素的掺杂量为750ppm；
在步骤b中，磷酸铁锂中Ti元素的掺杂量为750ppm。
其他内容均与实施例1相同。
对比例2
本对比例提供一种锂离子电池，与实施例1的区别在于：
在步骤a中，磷酸铁锂中Ti元素的掺杂量为1500ppm；
在步骤b中，磷酸铁锂中Ti元素的掺杂量为1500ppm。
其他内容均与实施例1相同。
循环性能测试：在25℃下，将实施例1-5和对比例1-2制备得到的电池以1P倍率充电到3.65V、以1P倍率放电到2.5V，进行满充满放循环测试，直至锂离子电池的容量小于初始容量的80％，记录循环圈数与能量效率，测试结果如表1所示。
表1

从表1中可以看出，实施例1-5的锂离子电池的能量效率明显高于对比例1和2。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本公开的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。
尽管上面已经示出和描述了本公开的实施例，可以理解的是，上述实施例是示例性的，不能理解为对本公开的限制，本领域的普通技术人员在本公开的范围内可以对上述实施例进行变化、修改、替换和变型。

Claims (11)

  1. 一种正极片，其中，包括：
    正极集流体；
    正极活性物质层，所述正极活性物质层设置在所述正极集流体的至少部分表面，所述正极活性物质层中包括正极活性物质，所述正极活性物质中掺杂有金属元素M，所述金属元素M用于增强所述正极活性物质对锂离子的脱嵌能力；
    设从所述正极集流体向所述正极活性物质层的方向为所述正极片的厚度方向，沿着远离所述正极集流体的厚度方向，所述正极活性物质层中的正极活性物质的所述金属元素M的掺杂量依次降低，且沿着所述正极片的厚度方向，距离所述正极集流体最近处的所述正极活性物质层中的正极活性物质的所述金属元素M的掺杂量与距离所述正极集流体最远处的所述正极活性物质层中的正极活性物质的所述金属元素M的掺杂量的比值小于等于8。
  2. 根据权利要求1所述的正极片，其中，所述正极活性物质层包括：
    第一正极活性物质层，所述第一正极活性物质层设置在所述正极集流体的至少部分表面；
    第二正极活性物质层，所述第二正极活性物质层设置在所述第一正极活性物质层的远离所述正极集流体的至少部分表面；
    且所述第一正极活性物质层中的正极活性物质的所述金属元素M的掺杂量与所述第二正极活性物质层中的正极活性物质的所述金属元素M的掺杂量的比值小于等于8。
  3. 根据权利要求2所述的正极片，其中，所述第一正极活性物质层中的正极活性物质的所述金属元素M的掺杂量与所述第二正极活性物质层中的正极活性物质的所述金属元素M的掺杂量的比值为3-5。
  4. 根据权利要求2或3所述的正极片，其中，所述第一正极活性物质层的正极活性物质中的所述金属元素M的掺杂量为2000ppm-7000ppm；
    和/或，所述第二正极活性物质层的正极活性物质中的所述金属元素M的掺杂量为500ppm～2000ppm。
  5. 根据权利要求1-4中任一项所述的正极片，其中，所述正极活性物质包括磷酸铁锂、镍酸锂、锰酸锂、钴酸锂、磷酸锰锂、磷酸钒锂、镍钴铝锂氧化物和镍钴锰锂氧化物中的至少一种。
  6. 根据权利要求1-5中任一项所述的正极片，其中，所述金属元素M包括Ti、V、Mg和Al中的至少一种。
  7. 根据权利要求1-6中任一项所述的正极片，其中，所述正极活性物质层的面密度为 300mg/1540.12mm2-500mg/1540.12mm2。
  8. 根据权利要求2-7中任一项所述的正极片，其中，所述第一正极活性物质层的面密度为150mg/1540.12mm2-250mg/1540.12mm2；
    和/或，所述第二正极活性物质层的面密度为150mg/1540.12mm2-250mg/1540.12mm2。
  9. 根据权利要求1-8中任一项所述的正极片，其中，所述正极活性物质层中还包括：导电剂、粘结剂和分散剂；
    所述正极活性物质、所述导电剂、所述粘结剂和所述分散剂的质量比为(94.5-98.5):(0.5-2.0):(1-3.0):(0-1)。
  10. 一种锂离子电池，其中，具有权利要求1-9中任一项所述的正极片。
  11. 一种储能设备，其中，具有权利要求10所述的锂离子电池。
PCT/CN2024/076150 2023-06-16 2024-02-05 正极片、锂离子电池和储能设备 Ceased WO2024255280A1 (zh)

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