WO2026007614A1 - 正极片及其制备方法、电池和用电系统 - Google Patents

正极片及其制备方法、电池和用电系统

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Publication number
WO2026007614A1
WO2026007614A1 PCT/CN2025/099515 CN2025099515W WO2026007614A1 WO 2026007614 A1 WO2026007614 A1 WO 2026007614A1 CN 2025099515 W CN2025099515 W CN 2025099515W WO 2026007614 A1 WO2026007614 A1 WO 2026007614A1
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WO
WIPO (PCT)
Prior art keywords
positive electrode
artificial graphite
active material
electrode active
electrode sheet
Prior art date
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Pending
Application number
PCT/CN2025/099515
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English (en)
French (fr)
Inventor
廖新淦
卢光波
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xiamen Hithium Energy Storage Technology Co Ltd
Original Assignee
Xiamen Hithium Energy Storage Technology Co Ltd
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Application filed by Xiamen Hithium Energy Storage Technology Co Ltd filed Critical Xiamen Hithium Energy Storage Technology Co Ltd
Publication of WO2026007614A1 publication Critical patent/WO2026007614A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/139—Processes of manufacture
    • 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 belongs to the field of battery technology, specifically relating to a positive electrode sheet and its preparation method, a battery, and an electrical system.
  • Lithium-ion batteries as a green power source, are widely used in energy storage base stations and other applications due to their advantages such as high energy density, long cycle life, low self-discharge rate, and environmental friendliness.
  • Lithium-ion batteries mainly consist of a positive electrode, separator, negative electrode, and electrolyte.
  • the positive electrode is a crucial component of the lithium-ion battery, and the preparation of the positive electrode slurry directly affects the overall performance of the battery. Furthermore, the dispersion state and contact uniformity of the conductive additives and active materials in the positive electrode significantly influence the battery's performance, such as its rate capability and cycle performance.
  • This application aims to at least partially address one of the technical problems in related technologies. Therefore, the purpose of this application is to provide a positive electrode sheet and its preparation method, a battery, and an electrical system.
  • This application adds artificial graphite and conductive carbon black to the positive electrode sheet. The two have a synergistic complementary effect, maximizing the electronic conduction between the positive electrode active material particles. Simultaneously, it improves the elongation of the positive electrode sheet.
  • the K-value of artificial graphite satisfies 0.6 ⁇ K ⁇ 1. Therefore, artificial graphite contacts a large number of positive electrode active material particles per unit length, resulting in more charge conduction sites, effectively improving the electronic conduction between active particles and significantly enhancing its conductivity, thereby significantly reducing the contact resistance of the positive electrode sheet.
  • a positive electrode is provided.
  • the positive electrode comprises:
  • a positive electrode active material layer is disposed on at least a portion of the surface of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode conductive agent, the positive electrode conductive agent comprising artificial graphite and conductive carbon black;
  • artificial graphite and conductive carbon black are uniformly distributed among the positive electrode active material particles.
  • the sheet-like artificial graphite establishes point-to-surface contact with the positive electrode active material particles, enabling long-range conductivity on the electrode.
  • the conductive carbon black being granular, adheres to the surface of the positive electrode active material particles, enabling short-range conductivity.
  • the two work synergistically exhibiting a good complementary effect, balancing both long-range and short-range conductivity, maximizing electron conduction between the positive electrode active material particles, and ensuring rapid electron transport. This also improves the dispersibility between the active material and the conductive agent.
  • the K-value of artificial graphite satisfies 0.6 ⁇ K ⁇ 1. Therefore, artificial graphite contacts a large number of positive electrode active material particles per unit length, resulting in more charge conduction sites, effectively improving electron conduction between active particles and significantly enhancing its conductivity. This improves the electrode's electronic conductivity, thereby significantly reducing the contact resistance (DCR) of the positive electrode sheet, thus reducing battery polarization and giving the positive electrode sheet superior electrical performance.
  • DCR contact resistance
  • this application proposes a method for preparing the positive electrode sheet described in the above embodiments. According to an embodiment of this application, the method includes:
  • the positive electrode slurry is coated on at least a portion of the surface of the positive electrode current collector and dried to obtain a positive electrode sheet.
  • this method can further reduce the degree of bending and mixing of artificial graphite in the slurry (i.e., further increase the K value of artificial graphite) by providing shear force in opposite directions, using surfactants, reducing stirring speed and dispersion speed, and premixing surfactants, artificial graphite and conductive carbon black.
  • this application proposes a battery.
  • the battery has a positive electrode as described in the above embodiments. This effectively reduces the battery's internal resistance during charging and discharging, improves battery efficiency, and enhances the battery's energy storage and release capabilities.
  • a fourth aspect of this application proposes an electrical system.
  • the electrical system includes: an electrical appliance and an energy storage device, wherein the energy storage device supplies power to the electrical appliance, and the energy storage device includes the battery described in the above embodiment.
  • the electrical system possesses all the advantages of the battery, which will not be elaborated further here.
  • Figure 1 is a SEM image of the positive electrode sheet of Embodiment 1 of this application.
  • Figure 2 is a SEM image of the positive electrode sheet of Embodiment 2 of this application.
  • Figure 3 is a SEM image of the positive electrode sheet of Embodiment 11 of this application.
  • Figure 4 is a SEM image of the positive electrode sheet of Embodiment 13 of this application.
  • Figure 5 is a SEM image of the positive electrode of Comparative Example 1 of this application.
  • Figure 6 is a SEM image of the positive electrode of Comparative Example 2 of this application.
  • Figure 7 is a SEM image of the positive electrode of Comparative Example 3 of this application.
  • conductive carbon black is used as a conductive additive in the positive electrode.
  • SP has good conductivity, and the conductive carbon black particles and active material particles have point-to-point contact.
  • the large specific surface area of the conductive carbon black makes dispersion difficult. This leads to the problem of easy agglomeration of the conductive agent and active material, preventing the formation of a good conductive network. This limits the electron conduction speed, resulting in high contact resistance and increased DCR (Displacement Resistance Rate).
  • DCR Displayment Resistance Rate
  • the artificial graphite and conductive carbon black SP are uniformly distributed between the positive active material particles, wherein the sheet-like artificial graphite establishes point-to-surface contact with the positive active material particles, enabling long-range conductivity on the electrode; the conductive carbon black SP is granular and adheres to the surface of the positive active material particles, enabling short-range conductivity.
  • artificial graphite satisfies 0.6 ⁇ K ⁇ 1. Therefore, artificial graphite has a larger number of contacting positive electrode active material particles per unit length, resulting in more charge conduction sites. This effectively improves the electronic conduction between active particles, significantly enhancing its conductivity and improving electrode electronic conductivity. Consequently, it significantly reduces the contact resistance (DCR) of the positive electrode sheet, thereby reducing battery polarization and giving the positive electrode sheet superior electrical performance.
  • DCR contact resistance
  • artificial graphite and conductive carbon black SP are added to the positive electrode sheet.
  • the artificial graphite and conductive carbon black SP are uniformly distributed among the positive electrode active material particles.
  • the artificial graphite has a sheet-like structure, thus establishing point-to-surface contact with the positive electrode active material particles instead of the conventional point-to-point contact, thereby enabling long-range conductivity on the electrode.
  • the conductive carbon black SP is granular and adheres to the surface of the positive electrode active material particles, enabling short-range conductivity.
  • the resistance of active material particles to slip on the surface of the current collector can be significantly reduced during electrode rolling, thereby fundamentally reducing the deformation of the current collector and improving the elongation of the positive electrode.
  • the K-value of artificial graphite satisfies 0.6 ⁇ K ⁇ 1.
  • a larger K-value indicates less bending and mixing in the artificial graphite. Therefore, artificial graphite contacts a greater number of positive electrode active material particles per unit length, resulting in more charge conduction sites. This effectively improves electron conduction between active particles, significantly enhancing its conductivity and reducing the contact resistance (DCR) of the positive electrode. Consequently, it reduces battery polarization and gives the positive electrode superior electrical performance. Simultaneously, it maximizes the role of the conductive agent, reducing its dosage and allowing for an increase in the amount of active material, thus improving battery capacity. It should be noted that a larger K-value in artificial graphite indicates less bending and mixing, meaning more positive electrode active material particles and more charge conduction sites per unit length.
  • the distance between the two endpoints of the artificial graphite along its length is 'a', as shown in Figure 1-4.
  • the actual length of the artificial graphite is 'b', which is the length when the bent artificial graphite is unfolded.
  • the degree of bending and mixing of artificial graphite is further limited, thereby increasing the number of positive electrode active material particles in contact with the artificial graphite per unit length and increasing the number of charge conduction sites. This further effectively improves the electronic conduction between active particles, significantly enhancing its conductivity and improving the electronic conductivity of the electrode, thereby further significantly reducing the contact resistance of the positive electrode sheet.
  • the combined mass percentage of artificial graphite and conductive carbon black is 1.5% to 2.5%, for example, it can be 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, etc. Therefore, by limiting the total content of the conductive agent within the above range, the electron conduction between the positive electrode active material particles can be maximized, ensuring rapid electron transport.
  • the combined mass percentage of artificial graphite and conductive carbon black is 1.7% to 2.0%.
  • the mass ratio of artificial graphite to conductive carbon black is (1/4 to 2):1, for example, 1/4:1, 1/2:1, 1:1, 2:1, etc.
  • the artificial graphite is in sheet form, with a thickness of 50nm to 200nm for each sheet, such as 50nm, 70nm, 100nm, 120nm, 150nm, 170nm, 200nm, etc., and a length of 1 ⁇ m to 60 ⁇ m for each sheet, such as 1 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, etc.
  • the thickness and length of the artificial graphite By limiting the thickness and length of the artificial graphite within the above ranges, it is possible to further ensure that the contact with the active material particles is a point-to-surface contact, thereby ensuring that the artificial graphite and the active material particles have more contact sites, reducing the internal resistance of the battery, improving the electronic conductivity of the electrode, and maximizing the role of the conductive agent.
  • a further preferred thickness is 5 ⁇ m to 40 ⁇ m.
  • artificial graphite is an equiaxed, irregular sheet-like sphere, which is different from graphene of different layers. It has a high thickness, is easy to disperse, and is easy to process. Artificial graphite has high compressibility, which can positively improve compaction. In addition, artificial graphite has good lubricity and flexibility, which can alleviate the situation where the active material separates from the current collector and conductive agent due to large volume shrinkage and expansion, forming inert single-particle "islands".
  • the average particle size of conductive carbon black SP is 15nm to 65nm, for example, it can be 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, etc.
  • the average particle size of conductive carbon black it is possible to further ensure that conductive carbon black SP adheres to the surface of positive electrode active material particles, realize short-range conductivity, further ensure the synergistic complementary effect between conductive carbon black SP and artificial graphite, take into account both long-range conductivity and short-range conductivity, thereby maximizing the electron conduction between positive electrode active material particles and ensuring rapid electron transport.
  • the conductive carbon black SP has a small particle size and is distributed in the pores formed by the active particles, resulting in stronger liquid absorption and retention.
  • the actual length of the artificial graphite and the number of positive electrode active material particles in direct contact satisfy the following: the ratio M of the number of positive electrode active material particles in direct contact with the artificial graphite to the actual length of the artificial graphite ranges from 4.5 to 7.5, where the unit of the actual length of the artificial graphite is ⁇ m, and the number of positive electrode active material particles is the count.
  • the ratio M of the number of positive electrode active material particles in direct contact with the artificial graphite to the actual length of the artificial graphite ranges from 4.5 to 7.5, where the unit of the actual length of the artificial graphite is ⁇ m, and the number of positive electrode active material particles is the count.
  • This further ensures that the artificial graphite contacts a large number of positive electrode active material particles per unit length, resulting in more charge conduction sites. This effectively improves the electronic conduction between active particles, significantly enhancing its conductivity and improving the electrode's electronic conductivity, thereby significantly reducing the contact resistance of the positive electrode sheet.
  • CP cross-sectional image refers to a cross-section taken along the thickness direction of the positive electrode sheet, and then observed using SEM.
  • SEM SEM
  • the positive electrode active material layer further includes a positive electrode active material and a positive electrode binder; the mass ratio of the positive electrode active material, the positive electrode binder and the positive electrode conductive agent is (95.64 ⁇ 97.12):(1.38 ⁇ 1.86):(1.5 ⁇ 2.5).
  • the particle size Dv50 of the positive electrode active material is 0.8 ⁇ m to 1.2 ⁇ m, which is beneficial for electrolyte wetting.
  • the positive electrode current collector may include a metal foil or a composite positive electrode current collector.
  • the metal foil may be aluminum foil.
  • the composite positive electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite negative electrode current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVDF-tetrafluoroethylene-propylene terpolymer PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer
  • tetrafluoroethylene-hexafluoropropylene copolymer tetrafluoroethylene-hexafluoropropylene copolymer
  • fluorinated acrylate resin fluorinated acrylate resin
  • this application proposes a method for preparing the positive electrode sheet according to the above embodiments. According to an embodiment of this application, the method includes:
  • a shear-stirring dispersion device is used to stir and disperse artificial graphite, conductive carbon black, and the first solvent to obtain an initial slurry.
  • the shear-stirring dispersion device can revolve and rotate, and can provide shear forces in opposite directions. Under the action of the opposite shear force, the artificial graphite in the slurry can effectively reduce the degree of bending and impurity of artificial graphite (i.e., increase the K value of artificial graphite), which is conducive to the subsequent steps to reform a conductive network with a higher effective chain density with the active material.
  • a shear-stirring dispersion device is used to stir and disperse the surfactant, artificial graphite, conductive carbon black, and a first solvent to obtain an initial slurry.
  • the surfactant effectively prevents the aggregation of the components, enabling the entire slurry system to construct a good three-dimensional conductive network.
  • the surfactant molecules are adsorbed on the surface of the artificial graphite conductive agent, and dispersion is achieved through repulsion and intermolecular forces, thereby further reducing the degree of impurity and curling of the artificial graphite (i.e., further increasing the K value of the artificial graphite).
  • the surfactant can be ultrasonically dissolved in the first solvent first, and then artificial graphite and conductive carbon black can be added for premixing.
  • the specific types of surfactants mentioned above are not particularly limited, and those skilled in the art can select them according to the actual situation.
  • the surfactants mentioned above include at least one of sodium dodecylbenzenesulfonate, sodium lignosulfonate, and hexadecyltrimethylammonium bromide.
  • the mass of the surfactant is 0.5% to 4% of the initial slurry, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, etc.
  • the content of the surfactant within the above range, it is possible to further ensure that the agglomeration of each component is effectively prevented, so that the entire slurry system can build a good three-dimensional conductive network, and the use of surfactant can further reduce the degree of impurity curling of artificial graphite.
  • the degree of bending and mixing of artificial graphite can be further reduced (i.e., the K value of artificial graphite is further increased), which is more conducive to the subsequent steps to reform a conductive network with a higher effective chain density with the active material.
  • This allows the artificial graphite to contact a larger number of positive electrode active material particles and more charge conduction sites per unit length, thereby effectively improving the electronic conduction between active particles.
  • step S100 By limiting the stirring speed, dispersion speed, and stirring time in step S100 to the above ranges, the effective dispersion of artificial graphite and conductive carbon black can be effectively ensured, and the degree of bending and impurity of artificial graphite can be further reduced (i.e., the K value of artificial graphite is further increased).
  • the specific type of the first solvent is not particularly limited, as long as it can achieve dispersion between the components.
  • the first solvent can be NMP.
  • S200 Add the positive electrode active material, positive electrode binder, and second solvent to the shearing and stirring dispersion device, and stir and disperse.
  • the positive electrode active material, positive electrode binder, and second solvent are added to a shear-stirring dispersion device and stirred and dispersed to obtain a positive electrode slurry.
  • This application by premixing the surfactant, artificial graphite, and conductive carbon black before adding the positive electrode active material and positive electrode binder, further facilitates the dispersion of artificial graphite and conductive carbon black in the slurry, further reduces the degree of bending and mixing of artificial graphite (i.e., further increases the K-value of artificial graphite), and further promotes the reformation of a conductive network with a higher effective chain density between the conductive agent and the active material.
  • the stirring speed is 20 r/min to 30 r/min
  • the dispersion speed is 200 r/min to 1000 r/min
  • the dispersion time is 2 h to 4 h.
  • the positive electrode slurry is coated onto at least a portion of the surface of the positive electrode current collector and dried to obtain the positive electrode sheet.
  • artificial graphite and conductive carbon black SP are added to the positive electrode slurry.
  • the sheet-like artificial graphite establishes point-to-surface contact with the positive electrode active material particles, enabling long-range conductivity on the electrode.
  • the conductive carbon black SP being granular, adheres to the surface of the positive electrode active material particles, enabling short-range conductivity.
  • the two complement each other effectively, balancing both long-range and short-range conductivity, maximizing electron conduction between the positive electrode active material particles, and ensuring rapid electron transport. This also improves the dispersibility between the active material and the conductive agent.
  • the K-value of artificial graphite satisfies 0.6 ⁇ K ⁇ 1. Therefore, artificial graphite contacts a large number of positive electrode active material particles per unit length, resulting in more charge conduction sites, effectively improving electron conduction between active particles and significantly enhancing its conductivity. This improves the electrode's electronic conductivity, thereby significantly reducing the contact resistance (DCR) of the positive electrode sheet, thus reducing battery polarization and giving the positive electrode sheet superior electrical performance.
  • DCR contact resistance
  • this method by providing shear forces in the opposite direction, using surfactants, reducing stirring and dispersion speeds, and premixing surfactants, artificial graphite, and conductive carbon black, can further reduce the degree of bending and mixing of artificial graphite in the slurry (i.e., further increase the K-value of artificial graphite).
  • This further facilitates the reformation of a conductive network with a higher effective chain density between the artificial graphite conductive agent and the active material, resulting in a larger number of positive electrode active material particles in contact per unit length and more charge conduction sites.
  • this application proposes a battery.
  • the battery has a positive electrode as described in the above embodiments. This effectively reduces the battery's internal resistance during charging and discharging, improves battery efficiency, and enhances the battery's energy storage and release capabilities.
  • the battery can be either a lithium-ion battery or a sodium-ion battery.
  • the following explanation uses a lithium-ion battery as an example.
  • the lithium-ion battery includes a positive electrode, a negative electrode, and a separator as described in the above embodiment, with the separator disposed between the positive and negative electrode.
  • active lithium ions repeatedly insert and extract between the positive and negative electrode.
  • the electrolyte serves to conduct ions between the positive and negative electrode.
  • the separator, disposed between the positive and negative electrode primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.
  • the specific material of the diaphragm is not particularly limited.
  • the diaphragm includes at least one of PP diaphragm, PE diaphragm, single-sided ceramic diaphragm, double-sided ceramic diaphragm, non-woven fabric diaphragm, and glass fiber diaphragm.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector.
  • the negative electrode active material layer includes a negative electrode active material (e.g., graphite), a negative electrode dispersant, a conductive agent, and a negative electrode binder.
  • the preparation method of the negative electrode sheet includes: mixing the negative electrode active material, negative electrode dispersant, conductive agent and negative electrode binder evenly according to the preset ratio, adding solvent and stirring evenly to form a negative electrode slurry, then coating it onto the current collector, drying it, and finally cutting it into a specific shape of negative electrode sheet for later use according to the different battery casings.
  • the positive and negative electrode sheets are added to the separator and wound. After winding, the positive and negative electrode tabs are welded. Then, the bare cell is packaged in an aluminum-plastic film. After packaging, the cell is vacuum baked for 10-20 hours. Then, after liquid injection, standing, high temperature and high pressure formation, degassing and packaging, and capacity testing, a lithium-ion battery with a double-layer coated positive electrode is obtained.
  • a fourth aspect of this application proposes an electrical system.
  • the electrical system includes: an electrical appliance and an energy storage device, wherein the energy storage device supplies power to the electrical appliance, and the energy storage device includes the battery described in the above embodiment.
  • the electrical system possesses all the advantages of the battery, which will not be elaborated further here.
  • the aforementioned energy storage devices can be either the power source of the electrical equipment or the energy storage unit of the electrical equipment.
  • These electrical equipment can include, but is not limited to, portable electronic devices such as mobile phones, tablets, laptops, desktop computers, smart bracelets, smartwatches, e-readers, and game consoles. They can also include, but are not limited to, vehicles such as cars, trucks, sedans, freight cars, bullet trains, high-speed trains, and electric vehicles. Furthermore, they can be used for various household appliances, such as, but not limited to, refrigerators, lights, and air conditioners.
  • the energy storage device of this application may include at least one of the following: a power energy storage device for the generation side of a power system, a power energy storage device (e.g., an electrochemical energy storage device) for the distribution side of a power system, and a power energy storage device for the user side of a power system.
  • a power energy storage device for the generation side of a power system e.g., a power energy storage device for the distribution side of a power system
  • a power energy storage device for the user side of a power system.
  • This embodiment provides a lithium-ion battery, the preparation method of which includes:
  • the conductive agent artificial graphite KS-6 and SP in a mass ratio of 1:1
  • NMP solvent a high-speed shear stirring and dispersing device
  • the stirring speed was 25 r/min
  • the dispersing speed was 250 r/min
  • the stirring time was 10 min.
  • lithium iron phosphate powder and PVDF powder were added to the above high-speed shear stirring and dispersing device and dry-mixed at 300 r/min.
  • a certain proportion of NMP was added and kneaded.
  • the remaining NMP was added and dispersed at 300 r/min for 3 h to obtain the positive electrode slurry.
  • the solid content of the positive electrode slurry was about 62 wt%
  • the mass ratio of lithium iron phosphate powder, PVDF powder and conductive agent was 96.62:1.48:1.90.
  • the positive electrode slurry is coated onto the positive electrode current collector aluminum foil, with a coating weight of 250 mg per unit area (1540.25 mm2 ). After drying, cold pressing, slitting, and cutting, the positive electrode sheet is obtained.
  • the negative electrode active material, artificial graphite, conductive carbon (SP), dispersant (CMC), and binder (SBR) were dispersed in deionized water at a mass ratio of 96.5:0.5:1:2 and mixed evenly to obtain a negative electrode slurry with a solid content of approximately 55%.
  • the negative electrode slurry was coated onto a copper foil current collector, with a coating weight of 122 mg per unit area (1540.25 mm2 ). After drying, cold pressing, slitting, and cutting, the negative electrode sheet was obtained.
  • ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1. Then, the dried electrolyte lithium salt LiPF6 was dissolved in the solvent, with LiPF6 accounting for 16% of the mass of the electrolyte.
  • a polyethylene film with a thickness of 16 micrometers was selected as the diaphragm.
  • the prepared positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator in the middle of the positive and negative electrodes to separate them. After winding, a bare cell is formed. After welding the tabs, the bare cell is assembled into the outer packaging. After injecting the prepared electrolyte, the cell is packaged, left to stand, formed, shaped, and tested for capacity, and finally a lithium-ion battery is prepared.
  • the surfactant sodium dodecylbenzenesulfonate is ultrasonically dissolved in NMP solvent to form a dispersant. Then, the conductive agent (artificial graphite KS-6 and SP in a 1:1 mass ratio) and the dispersant are premixed using a high-speed shear stirring dispersion device to obtain the initial slurry. The mass of the surfactant sodium dodecylbenzenesulfonate is 1% of the initial slurry.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the initial slurry was stirred at 20 r/min and dispersed at 100 r/min for 15 min.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the initial slurry was stirred at 30 r/min and dispersed at 300 r/min for 5 min.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the rotation speed of the lithium iron phosphate powder and PVDF powder after being added to the high-speed shear stirring and dispersing equipment is 500 r/min.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the rotation speed of the lithium iron phosphate powder and PVDF powder after being added to the high-speed shear stirring and dispersing equipment is 800 r/min.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the mass ratio of KS-6 to SP is 1/4:1.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the mass ratio of KS-6 to SP is 1/2:1.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the mass ratio of KS-6 to SP is 2:1.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the mass ratio of KS-6 to SP is 4:1.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the surfactant sodium dodecylbenzenesulfonate accounts for 2% of the initial slurry.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 2, except that:
  • the surfactant sodium dodecylbenzenesulfonate accounts for 4% of the initial slurry.
  • This embodiment provides a lithium-ion battery.
  • the preparation method of this embodiment is basically the same as that of Embodiment 11, except that:
  • the surfactant is a mixture of sodium dodecylbenzenesulfonate and hexadecyltrimethylammonium bromide in a mass ratio of 1:1.
  • This comparative example provides a lithium-ion battery.
  • the preparation method of this example is basically the same as that of Example 1, except that:
  • This comparative example provides a lithium-ion battery.
  • the preparation method of this example is basically the same as that of Example 1, except that:
  • lithium iron phosphate powder, conductive agent SP powder, and PVDF powder are added to a mixing tank and dry-mixed at 300 r/min. Then, a certain proportion of NMP is added for kneading. Finally, the remaining NMP is added and dispersed at high speed of 2000 r/min for 3 hours to form a positive electrode slurry.
  • This comparative example provides a lithium-ion battery.
  • the preparation method of this example is basically the same as that of Example 1, except that:
  • the conductive agent (KS-6 and SP in a mass ratio of 1:1) and NMP solvent were premixed using a high-speed shear stirring and dispersing device to obtain an initial slurry.
  • the stirring speed was 100 r/min
  • the dispersing speed was 560 r/min
  • the stirring time was 10 min.
  • lithium iron phosphate powder and PVDF powder were added to the above high-speed shear stirring and dispersing device and dry-mixed at 300 r/min.
  • a certain proportion of NMP was added for kneading.
  • the remaining NMP was added and dispersed at 2000 r/min for 3 h to obtain the positive electrode slurry.
  • the film resistivity and electrode elongation of the positive electrode sheets prepared in Examples 1-13 and Comparative Examples 1-3 were tested respectively, and the results are shown in Table 1.
  • the K value of artificial graphite KS-6 in the positive electrode sheets prepared in Examples 1-13 and Comparative Examples 1-3 was calculated, and the ratio M of the number of positive electrode active material particles in direct contact with artificial graphite KS-6 to the actual length of artificial graphite KS-6 was calculated, and the results are shown in Table 1.
  • the method for testing the film resistivity of the positive electrode is as follows:
  • test method for the electrode elongation of the positive electrode is as follows:
  • the method for calculating the ratio M of the number of positive electrode active material particles in direct contact with artificial graphite KS-6 to the actual length of artificial graphite KS-6 is as follows:
  • the CP diagram was processed using SolidWorks software, and the actual length b of KS-6 was calculated from the KS-6 profile curve.
  • test method for DCR of lithium-ion batteries at 50% SOC is as follows:
  • test method for the discharge DCR of a lithium-ion battery at 50% SOC is as follows:
  • Example 1 Compared with Example 1, the K and M values of Example 2 are further increased, the resistivity of the electrode film and the elongation of the electrode are further decreased, and the DCR of 50% SOC charging and 50% SOC discharging are further decreased. It can be seen that by adding surfactants during the formation of the initial slurry and the positive electrode slurry, the degree of bending impurities of artificial graphite KS-6 can be further reduced (i.e., the K and M values of artificial graphite KS-6 are increased), thereby reducing the resistivity of the positive electrode film and the elongation of the electrode, and reducing the DCR of 50% SOC charging and 50% SOC discharging of the battery.
  • Example 10 As can also be seen from Table 1, compared with Example 10, the charge-discharge DCR of Examples 2 and 7-9 is significantly reduced, and excessive KS-6 content is not conducive to the conduction of lithium ions in the electrode.
  • Example 11 As can be seen from Table 1, compared with Example 11, the K and M values of Example 13 are further increased, the resistivity of the electrode film and the electrode elongation are further decreased, and the DCR of 50% SOC charging and 50% SOC discharging are further decreased. It can be seen that the addition of the two surfactants can enhance the dispersion effect, thereby further reducing the degree of bending impurities of artificial graphite KS-6 (i.e., increasing the K and M values of artificial graphite KS-6), thereby reducing the resistivity of the positive electrode film and the electrode elongation, and reducing the DCR of 50% SOC charging and 50% SOC discharging of the battery.
  • references to terms such as "one embodiment,” “some embodiments,” “example,” “specific example,” or “some examples,” etc. refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application.
  • the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.
  • the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
  • those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

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Abstract

本申请属于电池技术领域，具体公开了正极片及其制备方法、电池和用电系统，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包括正极导电剂，所述正极导电剂包括人造石墨和导电炭黑；所述人造石墨沿长度方向的两端点之间的距离为a，所述人造石墨的实际长度为b，K＝a/b，满足0.6≤K＜1。

Description

正极片及其制备方法、电池和用电系统
优先权信息
本申请请求与2024年07月01日向中国国家知识产权局提交的、专利申请号为2024108736977、申请名称为“正极片及其制备方法、电池和用电系统”的中国专利申请的优先权和权益，其全部内容通过引用结合在本申请中。
技术领域
本申请属于电池技术领域，具体涉及一种正极片及其制备方法、电池和用电系统。
背景技术
锂离子电池作为一种绿色电源，因其能量密度高、循环寿命长、自放电率低、环境友好等优点，被广泛地应用于储能基站等。锂离子电池主要由正极片、隔膜、负极片、电解液等组成。其中锂离子电池正极片是锂离子电池的重要组成部分，锂离子电池正极浆料的制备直接影响着锂离子电池的综合性能，而正极片中导电添加剂与正极活性物质的分散状态以及接触均匀性很大程度上影响了锂离子电池的性能，例如会影响电池的倍率性能、循环性能等。
发明内容
本申请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，本申请的目的在于提出一种正极片及其制备方法、电池和用电系统。本申请通过在正极片中添加人造石墨和导电炭黑，两者相互协同具有良好的互补效应，能够最大限度地提升正极活性材料颗粒间的电子传导。同时，改善了正极片的延展率。另外，人造石墨的K值满足0.6≤K＜1，因此，人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，从而显著降低了正极片的接触电阻。
在本申请的一个方面，本申请提出了一种正极片。根据本申请的实施方案，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包括正极导电剂，所述正极导电剂包括人造石墨和导电炭黑；
所述人造石墨沿长度方向的两端点之间的距离为a，所述人造石墨的实际长度为b，K＝a/b，满足0.6≤K＜1。
根据本申请实施方案的正极片，人造石墨和导电炭黑均匀分布在正极活性材料颗粒间，其中，片状结构的人造石墨与正极活性材料颗粒之间构建点-面接触，能够实现电极上的长程导电；导电炭黑为颗粒状，附着在正极活性材料颗粒表面，能够实现短程导电，两者相互协同具有良好的互补效应，兼顾长程导电和短程导电，能够最大限度地提升正极活性材料颗粒间的电子传导，保证电子的快速传输。并改善了活性物质与导电剂之间的分散性。同时，改善了正极片的延展率。另外，人造石墨的K值满足0.6≤K＜1，因此，人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。
在本申请的第二个方面，本申请提出了一种制备以上实施方案所述的正极片的方法。根据本申请的实施方案，上述方法包括：
(1)采用剪切搅拌分散装置对人造石墨、导电炭黑和第一溶剂进行搅拌分散，得到初始浆料；
(2)将正极活性物质、正极粘结剂和第二溶剂加入所述剪切搅拌分散装置中，搅拌分散，得到正极浆料；
(3)将所述正极浆料涂覆在正极集流体的至少部分表面上，干燥，得到正极片。
根据本申请实施方案的制备上述正极片的方法，该方法通过提供相反方向的剪切力、表面活性剂的使用、降低搅拌转速和分散转速以及对表面活性剂、人造石墨和导电炭黑进行预混等方式，能够进一步降低人造石墨在浆料中的弯曲杂糅程度(即进一步增大了人造石墨的K值)，进一步有利于导电剂与活性物质重新形成一种有效链密度更高的导电网络，使人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。
在本申请的第三个方面，本申请提出了一种电池。根据本申请的实施方案，电池具有以上实施方案的正极片。由此，能够有效降低电池的充放电内阻，提高电池效率，增强电池的储能和释能能力。
在本申请的第四方面提出了一种用电系统。根据本申请的实施方案，用电系统包括：用电设备，以及储能装置，所述储能装置为所述用电设备进行供电，所述储能装置包括以上实施方案所述的电池。由此，所述用电系统具有所述电池的所有优点，在此不再赘述。
本申请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，或通过本申请的实践了解到。
附图说明
本申请的上述和/或附加的方面和优点从结合下面附图对实施方案的描述中将变得明显和容易理解，其中：
图1为本申请实施例1的正极片的SEM图；
图2为本申请实施例2的正极片的SEM图；
图3为本申请实施例11的正极片的SEM图；
图4为本申请实施例13的正极片的SEM图；
图5为本申请对比例1的正极片的SEM图；
图6为本申请对比例2的正极片的SEM图；
图7为本申请对比例3的正极片的SEM图。
具体实施方式
下面详细描述本申请的实施方案，所述实施方案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案是示例性的，旨在用于解释本申请，而不能理解为对本申请的限制。
相关技术中，正极片采用导电炭黑SP作为导电添加剂，导电炭黑SP具有较好的导电性，导电炭黑颗粒与活性物质颗粒之间呈点-点接触的形式。但是由导电炭黑作为导电剂制备的极片中，由于导电炭黑比表面较大导致其分散困难，存在着导电剂和活性物质易团聚且不能形成良好的导电网络的问题，从而限制了电子的传导速度，导致极片的接触电阻大，DCR增长。正极片在辊压过程中活性物质颗粒在压力的作用下进行滑移来达到紧密排列的目的，但是在活性物质颗粒的滑移过程中会导致集流体(例如铝箔)出现较为明显的延展，并且集流体的延展在整个极片范围内并不均匀，对极片的性能有着较大的影响。因此，辊压过程中减少因活性物质颗粒滑移而造成的集流体延展对后续加工性能和最终的电芯性能具有重要意义。
有鉴于此，在本申请的一个方面，本申请提出了一种正极片。根据本申请的实施方案，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，正极活性物质层包括正极导电剂，正极导电剂包括人造石墨和导电炭黑SP；人造石墨沿长度方向的两端点之间的距离为a，人造石墨的实际长度为b，K＝a/b，满足0.6≤K＜1。由此，人造石墨和导电炭黑SP均匀分布在正极活性材料颗粒间，其中，片状结构的人造石墨与正极活性材料颗粒之间构建点-面接触，能够实现电极上的长程导电；导电炭黑SP为颗粒状，附着在正极活性材料颗粒表面，能够实现短程导电，两者相互协同具有良好的互补效应，兼顾长程导电和短程导电，能够最大限度地提升正极活性材料颗粒间的电子传导，保证电子的快速传输。并改善了活性物质与导电剂之间的分散性。同时，改善了正极片的延展率。另外，人造石墨的K值满足0.6≤K＜1，因此，人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。
下面对本申请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：
本申请中，通过在正极片中添加人造石墨和导电炭黑SP，人造石墨和导电炭黑SP均匀分布在正极活性材料颗粒间，其中，人造石墨为片状结构，因此与正极活性材料颗粒之间构建点-面接触而不是常规的点-点接触形式，从而能够实现电极上的长程导电；导电炭黑SP为颗粒状，附着在正极活性材料颗粒表面，能够实现短程导电，两者相互协同具有良好的互补效应，兼顾长程导电和短程导电，能够最大限度地提升正极活性材料颗粒间的电子传导，保证电子的快速传输。并改善了活性物质与导电剂之间的分散性，在正极片中形成多维导电网络。
同时，选用SP和具有优异滑移性能的人造石墨(例如KS-6)为导电剂，在极片辊压时能够明显减轻活性物质颗粒在集流体表面滑移时的阻力，从根本上减轻集流体的变形，从而改善了正极片的延展率。
另外，人造石墨的K值满足0.6≤K＜1，K值较大即人造石墨的弯曲杂糅程度较小，因此，人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。同时，最大化发挥导电剂的作用，减少了导电剂的用量，从而可以增加活性物质的用量，提升电池容量。需要说明的是，人造石墨的K值越大，表明人造石墨的弯曲杂糅程度越小，则人造石墨在单位长度内，接触的正极活性材料颗粒数量越多，电荷传导位点越多。
需要说明的是，在SEM一定倍数下，人造石墨沿长度方向的两端点之间的距离为a，如附图1-4所示。人造石墨的实际长度为b，也就是将弯曲的人造石墨展开时的长度。
作为一些优选的实施方案，满足0.7≤K≤0.98，由此，进一步限定了人造石墨的弯曲杂糅程度较小，从而使人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而进一步有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而进一步显著降低了正极片的接触电阻。
根据本申请的一些具体实施方案，基于正极活性物质层的总质量为100％，人造石墨和导电炭黑的质量之和的占比为1.5％～2.5％，例如可以为1.5％、1.6％、1.7％、1.8％、1.9％、2.0％、2.1％、2.2％、2.3％、2.4％、2.5％等，由此，通过将导电剂的总含量限定在上述范围内，能够最大限度地提升正极活性材料颗粒间的电子传导，保证电子的快速传输。优选地，基于正极活性物质层的总质量为100％，人造石墨和导电炭黑的质量之和的占比为1.7％～2.0％。
进一步地，人造石墨和导电炭黑的质量比为(1/4～2):1，例如可以为1/4:1、1/2:1、1:1、2:1等，通过将人造石墨和导电炭黑的质量比限定在上述范围内，能够进一步确保两者之间的协同互补效应，兼顾长程导电和短程导电，从而能够最大限度地提升正极活性材料颗粒间的电子传导，保证电子的快速传输。发明人发现，如果人造石墨的含量过多，会阻碍锂离子的传导，从而导致极片性能变差；如果人造石墨的含量过少，会导致不能形成有效的导电网络，与SP的协同作用变差。
根据本申请的再一些具体实施方案，人造石墨为片状，单片人造石墨的厚度为50nm～200nm，例如可以为50nm、70nm、100nm、120nm、150nm、170nm、200nm等，单片人造石墨的长度为1μm～60μm，例如可以为1μm、10μm、20μm、30μm、40μm、50μm、60μm等，通过将人造石墨的厚度和长度限定在上述范围内，能够进一步确保与活性物质颗粒的接触为点-面接触，从而确保人造石墨与活性物质颗粒有更多的接触位点，减小电池的内阻，提高电极电子传导性，最大化发挥导电剂作用。进一步优选5μm-40μm。
在本申请的实施方案中，人造石墨为等轴的非规则片球状，区别于不同片层石墨烯，厚度高较易分散，易于加工，人造石墨的压缩性高，可正向提高压实，且人造石墨的润滑性以及柔韧性较好，可缓解活性材料由于较大的体积收缩、膨胀而与集流体、导电剂分离，形成惰性的单颗粒“孤岛”的情况。
根据本申请的又一些具体实施方案，导电炭黑SP的平均粒径为15nm～65nm，例如可以为15nm、20nm、25nm、30nm、35nm、40nm、45nm、50nm、55nm、60nm、65nm等，通过将导电炭黑的平均粒径限定在上述范围内，能够进一步确保导电炭黑SP附着在正极活性材料颗粒表面，实现短程导电，进一步确保导电炭黑SP与人造石墨之间的协同互补效应，兼顾长程导电和短程导电，从而能够最大限度地提升正极活性材料颗粒间的电子传导，保证电子的快速传输。
在本申请的实施方案中，导电炭黑SP的粒径小，分布于活性颗粒形成的孔隙中，吸液保液更强。
根据本申请的又一些具体实施方案，在CP截面图中，人造石墨的实际长度与其直接接触的正极活性物质颗粒的数量满足：与人造石墨直接接触的正极活性物质颗粒的数量与人造石墨的实际长度的比值M范围是4.5～7.5，人造石墨的实际长度的单位是μm，正极活性物质颗粒的数量为个数。由此，进一步确保了人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻。
可以理解的是，上述CP截面图是指沿正极片的厚度方向进行截面，再采用SEM进行观察，得到的SEM图即为CP截面图。
根据本申请的又一些具体实施方案，正极活性物质层还包括正极活性物质和正极粘结剂；正极活性物质、正极粘结剂和正极导电剂的质量比为(95.64～97.12)：(1.38～1.86)：(1.5～2.5)。
根据本申请的又一些具体实施方案，正极活性物质的粒径Dv50为0.8μm～1.2μm，由此，有利于电解液浸润。
在本申请一些实施方式中，正极集流体可包括金属箔片或复合正极集流体。例如，金属箔片可采用铝箔。复合正极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侧表面上的金属层，例如复合负极集流体可通过将金属材料(铝、铝合金、镍、镍合金、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)等基材)上而形成。
在本申请一些实施方式中，正极粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物和含氟丙烯酸酯树脂中的至少一种。
在本申请的第二个方面，本申请提出了一种制备以上实施方案的正极片的方法。根据本申请的实施方案，上述方法包括：
S100：对人造石墨、导电炭黑和第一溶剂进行搅拌分散
在该步骤中，采用剪切搅拌分散装置对人造石墨、导电炭黑和第一溶剂进行搅拌分散，得到初始浆料，剪切搅拌分散装置能够公转和自转，且能提供相反方向的剪切力。浆料中的人造石墨在相反剪切力的作用下，能有效降低人造石墨的弯曲杂糅程度(即增大了人造石墨的K值)，有利于后续步骤与活性物质重新形成一种有效链密度更高的导电网络，使人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。
根据本申请的一些具体实施方案，采用剪切搅拌分散装置对表面活性剂、人造石墨、导电炭黑和第一溶剂进行搅拌分散，得到初始浆料。上述表面活性剂能有效阻止各成分的团聚，使得整个浆料体系能够构建良好的三维导电网络，并且表面活性剂分子吸附在人造石墨导电剂表面，利用斥力和分子间作用力实现的分散，从而能够进一步降低人造石墨的杂糅卷曲的程度(即进一步增大了人造石墨的K值)，进一步有利于后续步骤与活性物质重新形成一种有效链密度更高的导电网络，使人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。
作为一个具体示例，可以先将表面活性剂超声溶解在第一溶剂中，然后加入人造石墨、导电炭黑进行预混。
上述表面活性剂的具体种类并不受特别限定，本领域人员可根据实际情况进行选择，作为一些优选的实施方案，上述表面活性剂包括十二烷基苯磺酸钠、木质素磺酸钠和十六烷基三甲基溴化铵中的至少一种。
根据本申请的一些具体实施方案，表面活性剂的质量为初始浆料的0.5％～4％，例如可以为0.5％、1％、1.5％、2％、2.5％、3％、3.5％、4％等，通过将表面活性剂的含量限定在上述范围内，能够进一步确保有效阻止各成分的团聚，使得整个浆料体系能够构建良好的三维导电网络，并且表面活性剂的使用能够进一步降低人造石墨的杂糅卷曲的程度。
在本申请的实施方案中，通过降低剪切搅拌分散装置的搅拌转速和分散转速能够进一步降低人造石墨的弯曲杂糅程度(即进一步增大了人造石墨的K值)，进一步有利于后续步骤与活性物质重新形成一种有效链密度更高的导电网络，使人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导。
根据本申请的再一些具体实施方案，在步骤S100中，搅拌转速为20r/min～30r/min(例如可以为20r/min、22r/min、24r/min、26r/min、28r/min、30r/min等)，分散转速为100r/min～300r/min(例如可以为100r/min、150r/min、200r/min、250r/min、300r/min等)，搅拌时间为5min～15min(例如可以为5min、6min、8min、10min、12min、15min等)，通过将步骤S100中的搅拌转速、分散转速和搅拌时间限定在上述范围内，既能有效确保人造石墨和导电炭黑的有效分散，又能进一步降低人造石墨的弯曲杂糅程度(即进一步增大了人造石墨的K值)。
在本申请的实施方案中，上述第一溶剂的具体种类并不受特别限定，只要能够实现各成分之间分散即可，例如第一溶剂可以为NMP。
S200：将正极活性物质、正极粘结剂和第二溶剂加入剪切搅拌分散装置中，搅拌分散
在该步骤中，将正极活性物质、正极粘结剂和第二溶剂加入剪切搅拌分散装置中，搅拌分散，得到正极浆料。本申请通过先对表面活性剂、人造石墨和导电炭黑进行预混，再加入正极活性物质和正极粘结剂进行混合的方式，能够进一步有利于人造石墨和导电炭黑在浆料中的分散，能够进一步降低人造石墨的弯曲杂糅程度(即进一步增大了人造石墨的K值)，进一步有利于导电剂与活性物质重新形成一种有效链密度更高的导电网络。
根据本申请的又一些具体实施方案，在步骤S200中，搅拌转速为20r/min～30r/min，分散转速为200r/min～1000r/min，分散时间为2h～4h，通过将步骤S200中的搅拌转速、分散转速和搅拌时间限定在上述范围内，既能有效确保人造石墨、导电炭黑、正极活性物质和正极粘结剂在浆料中的有效分散，又能进一步降低人造石墨的弯曲杂糅程度(即进一步增大了人造石墨的K值)。
S300：将正极浆料涂覆在正极集流体的至少部分表面上，干燥
在该步骤中，将正极浆料涂覆在正极集流体的至少部分表面上，干燥，得到正极片。
根据本申请实施方案的制备上述正极片的方法，通过在正极浆料中添加人造石墨和导电炭黑SP，其中，片状结构的人造石墨与正极活性材料颗粒之间构建点-面接触，能够实现电极上的长程导电；导电炭黑SP为颗粒状，附着在正极活性材料颗粒表面，能够实现短程导电，两者相互协同具有良好的互补效应，兼顾长程导电和短程导电，能够最大限度地提升正极活性材料颗粒间的电子传导，保证电子的快速传输。并改善了活性物质与导电剂之间的分散性。同时，改善了正极片的延展率。另外，人造石墨的K值满足0.6≤K＜1，因此，人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。
同时，该方法通过提供相反方向的剪切力、表面活性剂的使用、降低搅拌转速和分散转速以及对表面活性剂、人造石墨和导电炭黑进行预混等方式，能够进一步降低人造石墨在浆料中的弯曲杂糅程度(即进一步增大了人造石墨的K值)，进一步有利于人造石墨导电剂与活性物质重新形成一种有效链密度更高的导电网络，使人造石墨在单位长度内，接触的正极活性材料颗粒数量较多，电荷传导位点较多，从而有效改善了活性颗粒间的电子传导，对其导电能力的提升较为显著，提高了电极电子传导性，从而显著降低了正极片的接触电阻，即DCR降低，从而降低了电池的极化，使正极片具有较为优异的电性能。
在本申请的第三个方面，本申请提出了一种电池。根据本申请的实施方案，电池具有以上实施方案的正极片。由此，能够有效降低电池的充放电内阻，提高电池效率，增强电池的储能和释能能力。
在本申请的实施方案中，上述电池既可以是锂离子电池也可以是钠离子电池。以下以锂离子电池为例来说明。
具体地，锂离子电池包括以上实施方案的正极片、负极片和和隔膜，隔膜设置在正极片和负极片之间。在电池充放电过程中，活性离子锂离子在正极片和负极片之间往返嵌入和脱出。电解液在正极片和负极片之间起到传导离子的作用。隔离膜设置在正极片和负极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
上述隔膜的具体材质并不受特别限定，作为一些具体实施方案，上述隔膜包括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、导电剂和负极粘接剂。
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。
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10～20h，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。
在本申请的第四方面提出了一种用电系统。根据本申请的实施方案，用电系统包括：用电设备，以及储能装置，所述储能装置为所述用电设备进行供电，所述储能装置包括以上实施方案所述的电池。由此，所述用电系统具有所述电池的所有优点，在此不再赘述。
上述储能装置可以用作用电设备的电源，也可以用作用电设备的能量存储单元。上述用电设备可以包括但不限于手机、平板电脑、笔记本电脑、台式电脑、智能手环、智能手表、电子阅读器、游戏机等便携式电子设备。还可以包括但不限于汽车、卡车、轿车、货车、动车、高铁、电动自动车等交通工具。此外，还可以为各种家用电器，例如包括但不限于冰箱、电灯、空调等。
另外，本申请的储能装置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。
需要说明的是，上述针对电池所描述的特征和优点同样适用于该用电装置，此处不再赘述。
下面详细描述本申请的实施例，需要说明的是下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。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)首先，使用高速剪切搅拌分散设备将导电剂(质量比为1:1的人造石墨KS-6和SP)和NMP溶剂进行预混，得到初始浆料，搅拌转速25r/min，分散转速250r/min，搅拌10min。随后，将磷酸铁锂粉料和PVDF粉料一块加到上述高速剪切搅拌分散设备中，300r/min转速干混，之后加入一定比例的NMP进行捏合，最后再加入剩余NMP以300r/min的转速分散3h，得到正极浆料，正极浆料的固含量为62wt％左右，磷酸铁锂粉料、PVDF粉料和导电剂的质量比为96.62：1.48：1.90。
然后，将正极浆料涂布于正极集流体铝箔上，正极浆料单位面积(1540.25mm2)涂布重量为250mg。经过烘干、冷压、分条、裁片后，得到正极片。
2)负极片的制备
负极片的制备：将负极活性物质人造石墨、导电炭SP、分散剂CMC及粘结剂SBR按照质量比96.5:0.5:1:2分散于去离子水中进行混合均匀得到负极浆料，该负极浆料的固含量为55％左右。将负极浆料涂布于负极集流体铜箔上，负极浆料单位面积(1540.25mm2)涂布重量为122mg，经过烘干、冷压、分条、裁片后，得到负极片。
3)电解液的制备
在水分含量≤1ppm的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二甲酯(DMC)按质量比为1:1:1进行混合，之后将干燥的电解质锂盐LiPF6溶解到溶剂中，LiPF6在电解液中的质量占比为16％。
4)隔离膜
选用厚度为16微米的聚乙烯薄膜为隔膜。
5)电池的组装
将制备得到的正极片、隔膜、负极片按照顺序叠好，使得隔膜处于正负极的中间隔开正负极片，卷绕之后形成裸电芯，焊接极耳后将裸电芯装配到外包装中，注入制备得到的电解液后，对电芯进行封装、静置、化成、整形、容量测试等，最终制备得到锂离子电池。
实施例2
本实施例提供一种锂离子电池，本实施例与实施例1的制备方法基本相同，区别仅在于：
1)首先，将表面活性剂十二烷基苯磺酸钠超声溶解在NMP溶剂中形成分散剂，再使用高速剪切搅拌分散设备将导电剂(质量比为1:1的人造石墨KS-6和SP)和分散剂进行预混，得到初始浆料。表面活性剂十二烷基苯磺酸钠的质量为初始浆料的1％。
实施例3
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
初始浆料的搅拌转速20r/min，分散转速100r/min，搅拌15min。
实施例4
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
初始浆料的搅拌转速30r/min，分散转速300r/min，搅拌5min。
实施例5
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
将磷酸铁锂粉料和PVDF粉料加入高速剪切搅拌分散设备后的转速为500r/min。
实施例6
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
将磷酸铁锂粉料和PVDF粉料加入高速剪切搅拌分散设备后的转速为800r/min。
实施例7
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
KS-6和SP的质量比为1/4:1。
实施例8
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
KS-6和SP的质量比为1/2:1。
实施例9
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
KS-6和SP的质量比为2:1。
实施例10
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
KS-6和SP的质量比为4:1。
实施例11
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
表面活性剂十二烷基苯磺酸钠的质量为初始浆料的2％。
实施例12
本实施例提供一种锂离子电池，本实施例与实施例2的制备方法基本相同，区别仅在于：
表面活性剂十二烷基苯磺酸钠的质量为初始浆料的4％。
实施例13
本实施例提供一种锂离子电池，本实施例与实施例11的制备方法基本相同，区别仅在于：
表面活性剂为质量比为1:1的十二烷基苯磺酸钠和十六烷基三甲基溴化铵的混合物。
对比例1
本对比例提供一种锂离子电池，本实施例与实施例1的制备方法基本相同，区别仅在于：
1)使用双行星混料设备，将磷酸铁锂粉料、PVDF粉料一块加到搅拌罐里，300r/min转速干混，之后加入一定比例的NMP进行捏合，最后再加入剩余NMP进行高速2000r/min分散3h，形成正极浆料。
对比例2
本对比例提供一种锂离子电池，本实施例与实施例1的制备方法基本相同，区别仅在于：
1)使用双行星混料设备，将磷酸铁锂粉料、导电剂SP粉料、PVDF粉料一块加到搅拌罐里，300r/min转速干混，之后加入一定比例的NMP进行捏合，最后再加入剩余NMP进行高速2000r/min分散3h，形成正极浆料。
对比例3
本对比例提供一种锂离子电池，本实施例与实施例1的制备方法基本相同，区别仅在于：
1)使用高速剪切搅拌分散设备将导电剂(质量比为1:1的KS-6和SP)和NMP溶剂进行预混，得到初始浆料，搅拌转速100r/min，分散转速560r/min，搅拌10min。随后，将磷酸铁锂粉料和PVDF粉料一块加到上述高速剪切搅拌分散设备中，300r/min转速干混，之后加入一定比例的NMP进行捏合，最后再加入剩余NMP以2000r/min的转速分散3h，得到正极浆料。
分别对实施例1、2、11和13以及对比例1-3的制得的正极片进行SEM观测，结果如图1-7所示。
分别对实施例1-13以及对比例1-3制得的正极片的膜片电阻率以及极片延展率进行测试，结果如表1所示。分别对实施例1-13以及对比例1-3制得的正极片中的人造石墨KS-6的K值进行计算，并计算与人造石墨KS-6直接接触的正极活性物质颗粒的数量与人造石墨KS-6的实际长度的比值M，结果如表1所示。
分别对实施例1-13以及对比例1-3制得的锂离子电池的50％SOC充电DCR以及50％SOC放电DCR进行测试，结果如表1所示。
正极片的膜片电阻率的测试方法如下：
取电极片，采用可控压四线制双探头电阻法，控制电压，采集电流，求得膜片的电阻(R＝U/I)，然后计算出正极片的膜片电阻率。
正极片的极片延展率的测试方法如下：
在辊压之前，取一片长约1.5米的正极片，平直铺在大理石台面上，用细圆珠笔画线标识两段距离为1000±200mm直线，直线与陶瓷层直边垂直，直线上、极片中间区域用圆珠笔画测量点标识。用软尺实测两段直线测量点的距离D0，估读至0.1mm。正极片辊压后，正极片平直铺在大理石台面上，正极片两端用压块压住防止正极片收缩拱起。用软尺实测两段直线测量点的距离D1，估读至0.1mm。则正极片的极片延展率＝(D1-D0)/D0。
人造石墨KS-6的K值的测试以及计算如下：
利用SolidWorks软件对CP截面图进行处理，取KS-6两端点连线距离为a；通过KS-6轮廓曲线计算得KS-6实际长度b，即a/b＝K。
与人造石墨KS-6直接接触的正极活性物质颗粒的数量与人造石墨KS-6的实际长度的比值M的计算方法如下：
利用SolidWorks软件对CP图进行处理，通过KS-6轮廓曲线计算得KS-6实际长度b；对KS-6直接点面接触到的正极活性物质颗粒数量进行统计，记为c，即c/b＝M。
锂离子电池的50％SOC充电DCR的测试方法如下：
首先，利用0.5P恒功率充电，将电池从0％SOC充电到50％SOC状态下，接着用1C倍率充电30S，静止40S，放电30S，静止40S；记录倍率充电开始电压V1以及充电静止结束电压V2，充电DCR＝(V2-V1)/A，A为1C倍率下的电流。
锂离子电池的50％SOC放电DCR的测试方法如下：
首先，利用0.5P恒功率放电，将电池从100％SOC放电到50％SOC状态下，接着用1C倍率充电30S，静止40S，放电30S，静止40S，记录倍率放电开始电压V3以及放电静止结束电压V4，放电DCR＝(V4-V3)/A，A为1C倍率下的电流。
表1

从表1中可以看出，与对比例1和2相比，实施例1-13的正极片的膜片电阻率以及极片延展率明显降低，且实施例1-13的电池的50％SOC充电DCR以及50％SOC放电DCR明显降低。
从表1中还可以看出，与对比例3相比，实施例1-13的正极片中的人造石墨KS-6的K值以及M值明显增大，实施例1-13的正极片的膜片电阻率以及极片延展率明显降低，且实施例1-13的电池的50％SOC充电DCR以及50％SOC放电DCR明显降低。可见，在初始浆料和正极浆料的形成过程中，通过降低高速剪切搅拌分散设备的搅拌转速和分散转速，能够降低人造石墨KS-6的弯曲杂糅程度(即增大人造石墨KS-6的K值和M值)，从而能够降低正极片的膜片电阻率以及极片延展率，降低电池的50％SOC充电DCR以及50％SOC放电DCR。
从表1中还可以看出，与实施例1相比，实施例2的K值以及M值进一步增大，极片膜片电阻率以及极片延展率进一步降低，且50％SOC充电DCR以及50％SOC放电DCR进一步降低，可见，在初始浆料和正极浆料的形成过程中，通过添加表面活性剂，能够进一步降低人造石墨KS-6的弯曲杂糅程度(即增大人造石墨KS-6的K值和M值)，从而能够降低正极片的膜片电阻率以及极片延展率，降低电池的50％SOC充电DCR以及50％SOC放电DCR。
从表1中还可以看出，与实施例10相比，实施例2、实施例7-9的充放电DCR明显降低，KS-6含量过多不利于极片中锂离子的传导。
从表1中还可以看出，与实施例11相比，实施例13的K值以及M值进一步增大，极片膜片电阻率以及极片延展率进一步降低，且50％SOC充电DCR以及50％SOC放电DCR进一步降低，可见，添加两种表面活性剂相互协同，能够增大分散效果，从而能够进一步降低人造石墨KS-6的弯曲杂糅程度(即增大人造石墨KS-6的K值和M值)，从而能够降低正极片的膜片电阻率以及极片延展率，降低电池的50％SOC充电DCR以及50％SOC放电DCR。
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申请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申请的实施例，可以理解的是，上述实施例是示例性的，不能理解为对本申请的限制，本领域的普通技术人员在本申请的范围内可以对上述实施例进行变化、修改、替换和变型。

Claims (14)

  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包括正极导电剂，所述正极导电剂包括人造石墨和导电炭黑；
    所述人造石墨沿长度方向的两端点之间的距离为a，所述人造石墨的实际长度为b，K＝a/b，满足0.6≤K＜1。
  2. 根据权利要求1所述的正极片，其中，满足0.7≤K≤0.98。
  3. 根据权利要求1或2所述的正极片，其中，基于所述正极活性物质层的总质量为100％，所述人造石墨和所述导电炭黑的质量之和的占比为1.5％～2.5％；
    所述人造石墨和所述导电炭黑的质量比为(1/4～2):1。
  4. 根据权利要求1～3中任一项所述的正极片，其中，所述人造石墨为片状，单片所述人造石墨的厚度为50nm～200nm，单片所述人造石墨的长度为1μm～60μm。
  5. 根据权利要求1～4中任一项所述的正极片，其中，所述导电炭黑的平均粒径为15nm～65nm。
  6. 根据权利要求1～5中任一项所述的正极片，其中，在CP截面图中，所述人造石墨的实际长度与其直接接触的正极活性物质颗粒的数量满足：与所述人造石墨直接接触的所述正极活性物质颗粒的数量与所述人造石墨的实际长度的比值M范围是4.5～7.5，所述人造石墨的实际长度的单位是μm，所述正极活性物质颗粒的数量为个数。
  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还包括正极活性物质和正极粘结剂；所述正极活性物质、所述正极粘结剂和所述正极导电剂的质量为(95.64～97.12)：(1.38～1.86)：(1.5～2.5)。
  8. 根据权利要求7所述的正极片，其中，所述正极活性物质的粒径Dv50为0.8μm～1.2μm。
  9. 一种制备权利要求1～8中任一项所述正极片的方法，其中，包括：
    (1)采用剪切搅拌分散装置对人造石墨、导电炭黑和第一溶剂进行搅拌分散，得到初始浆料；
    (2)将正极活性物质、正极粘结剂和第二溶剂加入所述剪切搅拌分散装置中，搅拌分散，得到正极浆料；
    (3)将所述正极浆料涂覆在正极集流体的至少部分表面上，干燥，得到正极片。
  10. 根据权利要求9所述的方法，其中，在步骤(1)中，采用剪切搅拌分散装置对表面活性剂、人造石墨、导电炭黑和第一溶剂进行搅拌分散，得到初始浆料。
  11. 根据权利要求10所述的方法，其中，所述表面活性剂包括十二烷基苯磺酸钠、木质素磺酸钠和十六烷基三甲基溴化铵中的至少一种；
    和/或，所述表面活性剂的质量为所述初始浆料的0.5％～4％。
  12. 根据权利要求10或11所述的方法，其中，在步骤(1)中，搅拌转速为20r/min～30r/min，分散转速为100r/min～300r/min，搅拌时间为5min～15min；
    和/或，在步骤(2)中，搅拌转速为20r/min～30r/min，分散转速为200r/min～1000r/min，分散时间为2h～4h。
  13. 一种电池，其中，具有权利要求1～8中任一项所述的正极片或权利要求9～12中任一项所述方法制备的正极片。
  14. 一种用电系统，其中，包括：
    用电设备，以及
    储能装置，所述储能装置为所述用电设备进行供电，所述储能装置包括权利要求13所述的电池。
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